Posts by Jai Ganesh

Jai Ganesh · Dark Discussions at Cafe Infinity

2435) Alec Todd

Gist:

Work

The substances known as deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are found in nearly all cells in almost all organisms. The building blocks of DNA and RNA consist of nucleotides. In turn, these consist of what scientists call a nitrogen base, a sugar molecule, and one or more phosphate groups. Around 1940, Alexander Todd began to examine the composition of nucleotides more closely. Using chemical methods, Todd split nucleotides apart and compared their parts with substances that had been constructed from known components in a way that was already understood.

Summary

Alexander Robertus Todd, Baron Todd (born Oct. 2, 1907, Glasgow, Scot.—died Jan. 10, 1997, Cambridge, Eng.) was a British biochemist whose research on the structure and synthesis of nucleotides, nucleosides, and nucleotide coenzymes gained him the 1957 Nobel Prize for Chemistry.

After receiving doctorates from the universities of Frankfurt am Main (1931) and Oxford (1933), Todd held posts with the Lister Institute of Preventive Medicine, London, and the University of London before becoming professor of organic chemistry at the University of Manchester (1938–44) and then at Cambridge (1944–71), where he was also master of Christ’s College (1963–78). He was named chancellor of the University of Strathclyde in 1975 and was visiting professor at Hatfield Polytechnic (1978–86).

While at Manchester he began work on nucleosides, compounds that form the structural units of nucleic acids (DNA and RNA). In 1949 he synthesized a related substance, adenosine triphosphate (ATP), which is vital to energy utilization in living organisms. He synthesized two other important compounds, flavin adenine dinucleotide (FAD) in 1949 and uridine triphosphate in 1954. In 1955 he elucidated the structure of vitamin B12.

Todd also worked on the structure and synthesis of vitamin B1, vitamin E, and alkaloid substances found in marijuana and hashish. He studied other alkaloids as well, plant and insect pigments, and mold products, including penicillin. He served as chairman (1952–64) of the British government’s advisory committee on scientific policy, and in 1975 he was elected president of the Royal Society. Knighted in 1954, he was created a life peer in 1962 and made a member of the Royal Order of Merit in 1977.

Details

Alexander Robertus Todd, Baron Todd (2 October 1907 – 10 January 1997) was a British biochemist whose research on the structure and synthesis of nucleotides, nucleosides, and nucleotide coenzymes gained him the Nobel Prize for Chemistry in 1957.

Early life and education

Todd was born at Cathcart in outer Glasgow, the elder son of Alexander Todd, a clerk with the Glasgow Subway, and his wife, Jane Lowry.

He attended Allan Glen's School and graduated from the University of Glasgow with a bachelor's degree (BSc) in 1928. He received a doctorate (Dr Phil.nat.) from Goethe University Frankfurt in 1931 for his thesis on the chemistry of the bile acids.

Todd was awarded an 1851 Research Fellowship from the Royal Commission for the Exhibition of 1851, and, after studying at Oriel College, Oxford, he received another doctorate (DPhil) in 1933.

Career

Todd held posts with the Lister Institute, the University of Edinburgh (staff, 1934–1936) and the University of London, where he was appointed Reader in biochemistry.

In 1938, Alexander Todd spent six months as a visiting professor at California Institute of Technology, eventually declining an offer of faculty position.

Todd became the Sir Samuel Hall Chair of Chemistry and director of the Chemical Laboratories of the University of Manchester in 1938, where he began working on nucleosides, compounds that form the structural units of nucleic acids (DNA and RNA). At 31, he was the youngest professor of chemistry since Frankland. He was elected to membership of the Manchester Literary and Philosophical Society in 1938.

In 1944, he was appointed to the 1702 Chair of Chemistry in the University of Cambridge, which he held until his retirement in 1971. In 1949, he synthesised adenosine triphosphate (ATP) and flavin adenine dinucleotide (FAD). Todd served as a visiting professor at the University of Chicago in Autumn 1948 and University of Sydney in 1950.

By 1951, Todd and collaborators at Cambridge had determined by biochemical methods how the backbone of DNA is structured via the successive linking of carbon atoms 3 and 5 of the sugar to phosphates. This helped corroborate Francis Crick and James_Watson's X-ray structural work published in 1953.

In 1955, he helped elucidate the structure of vitamin B12, although the final formula and definite structure was determined by Dorothy Hodgkin and her team, and later worked on the structure and synthesis of vitamin B1 and vitamin E, the anthocyanins (the pigments of flowers and fruits) from insects (aphids, beetles) and studied alkaloids found in cannabis. He served as chairman of the Government of the United Kingdom's advisory committee on scientific policy from 1952 to 1964.

He is credited as the first person to synthesize H4-CBD and H2-CBD from Cannabidiol by hydrogenation as early as 1940.

He received the 1957 Nobel Prize in Chemistry "for his work on nucleotides and nucleotide co-enzymes."

Elected a Fellow of Christ's College, Cambridge in 1944, he served as Master from 1963 to 1978. Lord Todd became the first Chancellor of the new University of Strathclyde in 1965, and a visiting professor at Hatfield Polytechnic (1978–1986). Among his many honours, including over 40 honorary degrees, he was elected a Fellow of the Royal Society in 1942, a member of the United States National Academy of Sciences in 1955, a member of the American Academy of Arts and Sciences in 1957, and the American Philosophical Society in 1965. President of the Royal Society from 1975 to 1980, The Queen awarded him the Order of Merit in 1977.

In 1981, Todd became a founding member of the World Cultural Council.

Personal life and death

In 1937, Todd married Alison Sarah Dale (d. 1987), daughter of Nobel Prize winner Henry Hallett Dale, who like Todd, served as President of the Royal Society of London. They had a son and two daughters:

* Dr the Hon Alexander Henry Todd (b. 1939), educated at Oriel College, Oxford, Master Salters' Company (1999/2000), m. 1stly 1967 (div 1981) Joan Margaret Koester, m. 2ndly Patricia Mary Harvey Jones, daughter of Brigadier Alan Harvey Jones CBE TD, of Somerford Booths, Cheshire;
* The Hon Helen Jean Todd (b. 1941), m. 1963 Philip Edgar Brown, and has two sons and a daughter;
* The Hon Hilary Alison Todd (b. 1946).

Todd died in Cambridge on 10 January 1997 at the age of 89 following a heart attack.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#10751. What does the term in Biology Gene mean?

#10752. What does the term in Biology Gene pool mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#5947. What does the noun imbecile mean?

#5948. What does the verb (used with object) imbibe mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2570. What does the medical term Chondrodermatitis nodularis chronica helicis mean?

Jai Ganesh · This is Cool

2497) Jaguar

Gist

Jaguars rarely attack humans and will almost never do so without provocation. They will, however, attack and kill livestock that local farmers rely on for their livelihoods. This prompts local communities to hunt and kill jaguars in retaliation and to protect their herds.

There is a high risk associated with keeping this species as a pet. This is not a suitable pet.

Summary

The jaguar (Panthera onca) is a large cat species and the only living member of the genus Panthera that is native to the Americas. Its distinctively marked coat features pale yellow to tan colored fur covered by spots that transition to rosettes on the sides, although a melanistic black coat appears in some individuals. With a body length of up to 1.85 m (6 ft 1 in) and a weight of up to 158 kg (348 lb), it is the biggest cat species in the Americas and the third largest in the world. The jaguar's powerful bite allows it to pierce the carapaces of turtles and tortoises, and to employ an unusual killing method: it bites directly through the skull of mammalian prey between the ears to deliver a fatal blow to the brain.

The modern jaguar's ancestors probably entered the Americas from Eurasia during the Early Pleistocene via the land bridge that once spanned the Bering Strait. The oldest jaguar fossils found in North America date to between 0.85 to 0.82 million years ago. Today, the jaguar's range extends from the Southwestern United States across Mexico and much of Central America, the Amazon rainforest and south to Paraguay and northern Argentina. It inhabits a variety of forested and open terrains, but its preferred habitat is tropical and subtropical moist broadleaf forest, wetlands and wooded regions. It is adept at swimming and is largely a solitary, opportunistic, stalk-and-ambush apex predator. As a keystone species, it plays an important role in stabilizing ecosystems and in regulating prey populations.

The jaguar is threatened by habitat loss, habitat fragmentation, poaching for trade with its body parts and killings in human–wildlife conflict situations, particularly with ranchers in Central and South America. It has been listed as Near Threatened on the IUCN Red List since 2002. The wild population is thought to have declined since the late 1990s. Priority areas for jaguar conservation comprise 51 large areas inhabited by at least 50 breeding individuals, called Jaguar Conservation Units. They are located in 36 geographic regions from Mexico to Argentina.

The jaguar has featured prominently in the mythology of indigenous peoples of the Americas, including those of the Aztec and Maya civilizations.

Details:

What is the jaguar?

Jaguars are the only big cat in the Americas and the third biggest in the world after tigers and lions. They look a lot like leopards, which live in Africa and Asia, but jaguars’ spots are more complex and often have a dot in the center.

These powerful cats were worshipped as gods in many ancient South American cultures, and representations of the jaguar show up in the art and archaeology of pre-Columbian cultures across the jaguar’s range.

Diet and behavior

Unlike many other cats, jaguars do not avoid water. In fact, they are quite good swimmers. They hunt fish, turtles, and even caimans, using their incredibly powerful jaws to pierce the animals’ skulls. Jaguars also eat deer, peccaries, capybaras, tapirs, and a number of other land animals, which they prefer to ambush at night.

Jaguars live alone, and they’re territorial—they define their area by marking with their waste or clawing trees.

Females have litters of one to four cubs, which are blind and helpless at birth. The mother stays with them and defends them fiercely from any animal that may approach—even their own father. Young jaguars learn to hunt by living with their mothers for two years or more.

Range and habitat

Jaguars once roamed broadly from central Argentina all the way up to the southwestern United States. Since the 1880s, they’ve lost more than half their territory. Their main stronghold today is the Amazon Basin, though they still exist in smaller numbers through Central America as well.

They’re typically found in tropical rainforests but also live in savannas and grasslands.

Threats to survival

Jaguars face a number of threats, including habitat fragmentation and illegal killing. South and Central America’s high rates of deforestation—for grazing land, agriculture, and other uses—have not only destroyed jaguars’ habitat but also broken it up. Fragmented forests mean that cats get boxed into patches of forest and can’t travel far to find new mates. That kind of isolation can lead to inbreeding and local extinctions.

Another threat jaguars face is retaliatory killings from ranchers. As grazing land replaces forests, jaguars are more likely to hunt cattle. In response—and sometimes in anticipation—cattle owners kill jaguars.

Poaching is another growing problem for jaguars. They’ve long been hunted for their pelts, and now there’s a growing illegal, international trade in jaguar teeth and jaguar bone products going to China.

Conservation

Jaguars are classified as near-threatened by the International Union for the Conservation of Nature. The species has national protections in almost every country it’s found, and trade in its parts is banned by CITES, a global treaty that regulates the cross-border wildlife trade. Still, poaching and the illegal trade continues so strengthening law enforcement is important.

There are major efforts to support and develop jaguar corridors to connect isolated populations as well as to work with ranchers to reduce human-jaguar conflict. Workshops help ranchers learn better husbandry practices, and a growing number of programs compensate ranchers when they lose cattle to jaguars, so that they’re less motivated to kill the cat in retaliation.

Fighting deforestation, which a number of international NGOs and indigenous groups are involved in, is critical.

Additional Information

Big cats are some of the most captivating wild animals. Elusive, powerful, and graceful. Lions and tigers are easily identifiable and greatly loved, but there’s far more to the world of big cats than these icons.

Jaguars are some of the most beautiful and mysterious big cats in the world, but few people know much about them. World Animal Protection wants to put that right.

We’ve produced a short documentary Jaguar Spirit, to highlight these incredible animals and the challenges they face. To get you ready for the documentary, let’s whet your appetite with some amazing jaguar facts.

1. Jaguars are the third largest cats in the world

Jaguars are “big” cats packed into a smaller form factor. They’re the largest cat in the Americas and are the third largest cat in the world, behind tigers and lions. Male Jaguars weigh up to 120kg, while the smaller females reach a maximum of 100kg. To put this in context, jaguars are about half the weight of a lion, but more than double that of a cheetah.

However, jaguars are no taller than a meter, making them powerful but relatively compact compared to lions and tigers.

2. Jaguars were revered by Mesoamerican civilizations

In Mesoamerican indigenous communities, jaguars were one of the most revered animals. Every major Mesoamerican civilization had a jaguar god, many of which were important parts of their religion. These communities viewed jaguars as symbols of strength and power.

For example, the Aztecs named their most elite warriors “cuāuhocēlōtl”, a combination of the Aztec words for eagle and jaguar. They wore costumes that made them resemble these majestic cats and lead their communities both on the battlefield and at home. In Aztec culture, many believed that shamans could transform into jaguars at will and would become jaguars after they died.

3. Jaguar spots are unique

Learning to tell jaguars apart from other big cats is easy. They have beautiful tan and orange fur covered with black spots known as rosettes.

These rosettes are different from the spots on any other cat. Each rosette is a jagged circle that makes up an outer ring with a single black spot in the middle.

Other spotted cats have the ring that characterises the rosettes, but none have the central spot of the jaguar.

4. Jaguars love swimming

Unlike most domestic cats, jaguars are excellent swimmers and love the water. They can fully submerge and dive in pursuit of prey if needed and won’t hesitate to attack prey animals in the water.

5. Jaguars look after their cubs

Jaguars don’t have big litters. They typically have two cubs at one time (though they can have up to four). The cubs are born completely helpless and blind. They remain with their mother for two years as they grow and learn to hunt and take care of themselves.

Jaguars are sentient beings, meaning they think and feel and have personalities and needs of their own. The breakthrough research and studies of animals' feelings and emotions show how the life of a wild animal, like a jaguar, is mentally and physically better in the wild with its cubs.

6. Jaguars are exploited for commercial purposes

Jaguars aren’t some of the most endangered animals in the world, but that doesn’t mean that the species is thriving. There are only 173,000 jaguars left in the wild, the population of jaguars is “near threatened”. Regardless of their status, jaguars should not be exploited for any commercial purposes. They are wildlife and deserve a life in the wild.

7. Jaguars live primarily in the rainforest

As opportunistic ambush predators, jaguars aren’t well-suited to large open spaces. Instead, the natural habitat of jaguars is rainforests and wetlands. Approximately half of the world’s population of jaguars live in Brazil.

The rest can be found in Mexico and Central and South America, including northern Argentina.

8. Jaguars are fast

Cheetahs are the first to come to mind when you think of fast runners in the animal kingdom. Jaguars can’t quite reach the 70 miles per hour of the cheetah, but they reach a very respectable 50mph.

This makes them the second-fastest big cats in the world. They also have an impressive ability to jump and climb when necessary.

9. Jaguars aren’t fussy eaters

Jaguars are carnivores, like all other cats. On land, they will commonly hunt deer, capybaras, and tapirs. And they’re just as comfortable in the water, seeking out fish, turtles, and caiman to meet their appetite.

As opportunistic hunters, however, they will prey on almost any animal they come across.

These techniques and their incredible bite power allows them to dispatch prey as large as cows.

10. Jaguars are crepuscular

Most of us think of animals as being either diurnal or nocturnal, but jaguars don’t fit into this pattern. They can be active either during the day or at night.

In fact, jaguars are considered crepuscular and nocturnal, meaning they’re most active during dusk and dawn. These are the times when they’re most likely to be hunting. That said, it’s also common to find them hunting during the day.

11. Jaguars travel long distances

Jaguars can regularly travel over six miles per day in search of food. They’re solitary animals, marking their territory and only getting together with others to mate. Males do not remain with females to avoid the risk of infanticide.

Where space allows, jaguars can have territories of up to 54 square miles.

12. Jaguars are struggling with the loss of their habitats

Jaguars are being threatened because their habitats are being lost to deforestation and other human activities. Much of this land has been appropriated for agricultural activities such as cattle ranching and crops used to produce animal feed.

Any reduction in habitat makes it harder for these solitary cats to maintain sufficient territory to feed themselves. It also increases the risk of conflict between individual animals.

13. Jaguar prey have also reduced in number

The loss of habitat has also impacted the animals that jaguars rely on for food. When prey becomes scarce, jaguars start looking for alternative food sources, including agricultural livestock.

The people living in areas frequented by jaguars attempt to protect their animals, which unfortunately often leads to killing the big cats threatening their livelihood.

14. Jaguars are facing increased risk from fire

Jaguar territories are increasingly at risk from fire, threatening both jaguars and the prey animals they rely on, further exacerbating the problems they already face.

Factory farming methods are becoming increasingly common throughout the Amazon, with catastrophic consequences. Fires are often deliberately set to clear large swathes of land quickly.

Once rainforests have been removed, they are replaced with monoculture crops, which are more vulnerable to wildfires than the original ecosystems.

15. Jaguars are popular targets for poaching

Despite their impressive camouflage, speed, and agility, jaguars are popular with poachers. Their beautiful fur means that they command high prices for their pelts and skins, and their sharp teeth and claws are seen as valuable trophies.

Beyond poaching for trophies, jaguars are often captured and sold as exotic pets, to private wildlife collectors, or as tourist attractions.

16. Jaguars are used in traditional Asian medicine

Jaguars are also often killed for use in traditional Asian medicine. They are typically boiled whole until they reduce down into a paste used for various purposes, from treating arthritis to improving sexual performance.

None of these animal-derived products are scientifically validated or effective.

Jai Ganesh · Dark Discussions at Cafe Infinity

Come Quotes - V

1. Communism has never come to power in a country that was not disrupted by war or corruption, or both. - John F. Kennedy

2. The changes in our life must come from the impossibility to live otherwise than according to the demands of our conscience not from our mental resolution to try a new form of life. - Leo Tolstoy

3. It is clear our nation is reliant upon big foreign oil. More and more of our imports come from overseas. - George W. Bush

4. Where would you be without friends? The people to pick you up when you need lifting? We come from homes far from perfect, so you end up almost parent and sibling to your friends - your own chosen family. There's nothing like a really loyal, dependable, good friend. Nothing. - Jennifer Aniston

5. An invasion of armies can be resisted, but not an idea whose time has come. - Victor Hugo

6. It's never paid to bet against America. We come through things, but its not always a smooth ride. - Warren Buffett

7. Begin at the beginning and go on till you come to the end; then stop. - Lewis Carroll

8. Corruption is the enemy of development, and of good governance. It must be got rid of. Both the government and the people at large must come together to achieve this national objective. - Pratibha Patil.

Jai Ganesh · This is Cool

Microwave Oven

Gist

A microwave oven heats food using electromagnetic waves that excite water molecules, causing them to vibrate and generate heat, allowing for quick reheating, defrosting, and cooking, making it a convenient, energy-efficient appliance for modern kitchens, especially for busy individuals. Its main uses include rapidly warming leftovers, thawing frozen foods, making popcorn, steaming vegetables, and even baking with convection models.

The most common types of microwaves include built-in, over-the-range, countertop, undercounter, wall oven and microwave combination, smart and convection microwaves.

Summary

A microwave oven, or simply microwave, is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces polar molecules in the food to rotate and produce thermal energy (heat) in a process known as dielectric heating. Microwave ovens heat food quickly and efficiently because the heating effect is fairly uniform in the outer 25–38 mm (1–1.5 inches) of a homogeneous, high-water-content food item.

The development of the cavity magnetron in the United Kingdom made possible the production of electromagnetic waves of a small enough wavelength (microwaves) to efficiently heat up water molecules. American electrical engineer Percy Spencer is generally credited with developing and patenting the world's first commercial microwave oven, the "Radarange", which was first sold in 1947. He based it on British radar technology which had been developed before and during World War II.

Raytheon later licensed its patents for a home-use microwave oven that was introduced by Tappan in 1955, but it was still too large and expensive for general home use. Sharp Corporation introduced the first microwave oven with a turntable between 1964 and 1966. The countertop microwave oven was introduced in 1967 by the Amana Corporation. After microwave ovens became affordable for residential use in the late 1970s, their use spread into commercial and residential kitchens around the world, and prices fell rapidly during the 1980s. In addition to cooking food, microwave ovens are used for heating in many industrial processes.

Microwave ovens are a common kitchen appliance and are popular for reheating previously cooked foods and cooking a variety of foods. They rapidly heat foods which can easily burn or turn lumpy if cooked in conventional pans, such as butter, fats, chocolate, or porridge. Microwave ovens usually do not directly brown or caramelize food, since they rarely attain the necessary temperature to produce Maillard reactions. Exceptions occur in cases where the oven is used to heat frying-oil and other oily items (such as bacon), which attain far higher temperatures than that of boiling water.

Microwave ovens have a limited role in professional cooking, because the boiling-range temperatures of a microwave oven do not produce the flavorful chemical reactions that frying, browning, or baking at a higher temperature produces. However, there are hybrid appliances that combine infrared radiation, hot air, and microwaves, such as convection microwave ovens.

Details

"Microwave" is just short for "microwave oven". Both terms mean the same thing: an appliance that uses microwave radiation to heat food. Cooking food in this way is called "microwaving". An oven, on the other hand, has a heating element which heats the air inside, which then heats the food. Cooking food in this way is generally called "baking", though there are a lot of other things (e.g. roasting) you can also reasonably do in an oven.

So if all you have is a microwave, then all you can do is microwave (not bake). And if you have an oven, then you can bake (but of course you can't microwave).

There also exist combinations, which are capable of both microwaving and baking, i.e. they have a microwave emitter and a heating element. However, remember that in the US - and thus on much of the internet - something talking about a "microwave oven" likely does not mean this combination, but simply microwave heating. Names like "convection microwave oven with grill", "combination microwave/oven" do refer to these combinations, though. I've also seen "speed oven". You may sometimes have seen people referring to these combination microwave/ovens as a "microwave oven" (I think this may be common in Indian English), but that's really just imprecise language.

Some sites say that a "microwave" is only for heating or re-heating cooked food. Whereas, in "microwave ovens", you can microwave and bake. Is that true?

It sounds like in this statement, "microwave oven" is careless language, referring to a combination microwave and oven. (It doesn't make any sense at all otherwise; the two things are the same thing, so of course you can do the same things in them.)

So the question is really, what can you do in a microwave vs an oven, or a combination microwave/oven?

It's true that microwaves are mainly used for reheating cooked food, and it's true that they can't actually bake. However, they can do a lot more than reheat food; there are a lot of kinds of cooking besides baking. For example, microwaves are great at simmering/boiling and steaming, and it doesn't matter if the food was cooked already or not. The recipes you're talking about are probably mostly in those kinds of categories, but if you're interested, How do I know if a food or recipe can be made in a microwave oven? discusses in a bit more detail what works in microwaves.

The big things that you can do with ovens but not microwaves are the things that actually need the steady dry heat of baking. You can't bake bread or cookies or roast a chicken in a microwave. Microwaves hold in a lot of steam and don't get terribly hot, so you can't generally get things to brown or crisp up. They also don't really hold a temperature like you need for baking, they just pump more and more heat into the food.

Additional Information

A microwave oven heats food by passing microwave radiation through it, a process known as dielectric heating. Microwaves are a form of non-ionizing electromagnetic radiation with a frequency between 300 MHz and 300 GHz. Microwave ovens use frequencies in one of the ISM (industrial, scientific, medical) bands, so they do not interfere with other vital radio services.

Dielectric heating takes advantage of the electric dipole structure of water molecules, fats, and many other substances in the food. These molecules have a partial positive charge at one end and a partial negative charge at the other. In an alternating electric field, they will rotate as they continually try to align themselves to the field. Once the electrical field's energy is initially absorbed, heat will gradually spread through the object similarly to any other contact with a hotter body.

It is a common misconception that microwave ovens heat food at a special resonance of water molecules in the food. Instead, all polar molecules participate, and dielectric heating for each molecule can happen over a wide range of frequencies.

Typically, consumer ovens work around a nominal 2.45 gigahertz (GHz) – a wavelength of 12.2 centimetres (4.80 in) in the 2.4 GHz to 2.5 GHz ISM band – while large industrial / commercial ovens often use 915 megahertz (MHz) – 32.8 centimetres (12.9 in). Among other differences, the longer wavelength of a commercial microwave oven allows the initial heating effects to begin deeper within the food or liquid, and therefore become evenly spread within its bulk sooner, as well as raising the temperature deep within the food more quickly.

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Jai Ganesh · Science HQ

Myopia

Gist

Myopia, or nearsightedness, is a common, often progressive refractive error where the eyeball grows too long or the cornea is too curved, causing light to focus in front of the retina rather than on it. It results in blurred distant vision, with symptoms like eye strain, headaches, and squinting. Affecting roughly 30% of the global population, it is commonly treated with glasses, contacts, or refractive surgery (e.g., LASIK).

Myopia, or nearsightedness, is a common vision condition where distant objects appear blurry because the eye focuses light in front of the retina instead of directly on it, often due to an elongated eyeball or a cornea that is too curved. It allows clear vision for close-up tasks but makes seeing far away difficult, leading to squinting, eye strain, and headaches. It's typically managed with glasses, contacts, or surgery, and its development is linked to genetics and increased near work like screen time.

Summary

Myopia, also known as near-sightedness and short-sightedness, is an eye condition where light from distant objects focuses in front of, instead of on, the retina. As a result, distant objects appear blurry, while close objects appear normal. Other symptoms may include headaches and eye strain. Severe myopia is associated with an increased risk of macular degeneration, retinal detachment, cataracts, and glaucoma.

Myopia results from the length of the eyeball growing too long or less commonly the lens being too strong. It is a type of refractive error. Diagnosis is by the use of cycloplegics during eye examination.

Myopia is less common in people who spent more time outside during childhood. This lower risk may be due to greater exposure to sunlight. Myopia can be corrected with eyeglasses, contact lenses, or by refractive surgery. Eyeglasses are the simplest and safest method of correction. Contact lenses can provide a relatively wider corrected field of vision, but are associated with an increased risk of infection. Refractive surgeries such as LASIK and PRK permanently change the shape of the cornea. Other procedures include implantable collamer lens (ICL) placement inside the anterior chamber in front of the natural eye lens. ICL does not affect the cornea.

Myopia is the most common eye disorder and is estimated to affect 1.5 billion people (22% of the world population). Rates vary significantly in different areas of the world. Rates among adults are between 15% and 49%. Among children, it affects 1% of rural Nepalese, 4% of South Africans, 12% of people in the US, and 37% in some large Chinese cities. In China the proportion of girls is slightly higher than boys. Rates have increased since the 1950s. Uncorrected myopia is one of the most common causes of vision impairment globally along with cataracts, macular degeneration, and vitamin A deficiency.

Details

Myopia (nearsightedness) is a common condition that’s usually diagnosed before age 20. It affects your distance vision — you can see objects that are near, but you have trouble viewing objects that are farther away like grocery store aisle markers or road signs. Myopia treatments include glasses, contact lenses or surgery.

Overview:

What is myopia?

Myopia is the medical name for nearsightedness, which means that you can see objects that are near clearly but have difficulty seeing objects that are farther away. For example, if you have nearsightedness, you may not be able to make out highway signs until they’re just a few feet away.

Myopia affects a significant percentage of people. It’s an eye focus disorder that’s normally corrected with eyeglasses, contact lenses or surgery.

How common is myopia?

Myopia is common. According to one estimate, more than 40% of people in the U.S. have nearsightedness. This number is rapidly rising, especially among school-aged children. Eye experts expect this trend to continue in the coming decades.

One in four parents has a child with some degree of nearsightedness. Some eye experts believe that if your child spends a great deal of time engaged in “near” activities, such as reading or using smartphones and computers, it may raise their risk of developing myopia.

Are there types of myopia?

Eye specialists divide myopia broadly into simple myopia and pathologic myopia. Pathologic myopia is a newer name for degenerative myopia.

People with simple myopia have contact lenses or eyeglasses that help provide clear vision, while those with pathologic myopia may not be able to have clear vision even with corrective lenses.

Symptoms and Causes:

What are the symptoms of myopia?

If you have nearsightedness, you may notice:

* Faraway objects look blurred or fuzzy.
* Close items appear clear.
* Headaches.
* Eye strain.
* Squinting.
* Tiredness when driving, playing sports or looking more than a few feet away.

Some additional symptoms of myopia to watch for in your children include:

* Poor performance in school.
* Shortened attention span.
* Holding objects close to their face.

Most cases of myopia are mild and easily managed with eyeglasses, contact lenses or refractive surgery.

What causes myopia?

If you have myopia, more than likely, at least one or both of your biological parents do, too. Eye experts are still unsure of the exact cause of myopia, but believe it to be a mix of hereditary and environmental factors.

It’s possible that you can inherit the ability to be myopic. If your lifestyle produces just the right conditions, you’ll develop it. For example, if you use your eyes for a lot of close-up work, like reading or working on a computer, you may develop myopia.

Myopia usually appears in childhood. Typically, the condition can worsen in early childhood but tends to level off by the end of teen years.

Because the light coming into your eyes doesn’t focus correctly, images are unclear. Think of it as being a little like a misdirected spotlight. If you shine a spotlight on the incorrect place in the distance, you won’t be able to see the correct object clearly.

What are the risk factors for myopia?

Risk factors for nearsightedness may include:

* A family history of myopia.
* Spending a lot of time doing “close-up” work, like reading or using screens like those on smartphones or computers.
* Not spending a lot of time outdoors. Certain studies indicate that this may be a factor in developing myopia.
* Ethnicity. Some groups of people have higher rates of myopia than others.

What are the complications of myopia?

In most cases, providers can treat nearsightedness with glasses, contact lenses or corrective surgery, like LASIK. However, some cases of pathologic myopia can lead to more serious eye conditions, including:

* Cataracts.
* Glaucoma.
* Optic neuropathy.
* Neovascularization.
* Retinal detachment.

Pathologic myopia may make you more vulnerable to other more serious eye conditions. These include:

* Developing unwanted blood vessels in your eye (neovascularization).
* Glaucoma.
* Myopic optic neuropathy.
* Retinal detachment.
* Cataracts.
* High myopia happens when your child’s eyeballs are too long, or their corneas are too steep.

Diagnosis and Tests:

How is myopia diagnosed?

An eye care provider can diagnose myopia using standard eye exams. Providers usually diagnose myopia in childhood, but it can also develop in adults because of visual stress or diabetes.

Testing an adult for myopia

Your provider will evaluate how your eyes focus light and measure the power of any corrective lenses you may need. First, they’ll test your visual acuity (sharpness) by asking you to read letters on an eye chart. Then, they’ll use a lighted retinoscope to measure how your retina reflects light.

Your provider may also use a phoropter. A phoropter is an instrument that measures the amount of your refractive error by placing a series of lenses in front of your eyes. This is how your provider measures the lens strength you need.

Testing your child for myopia

Your pediatrician will check your child’s eyes at each well-child visit. A first eye exam should be before age 1, if possible. If your child has no evident eye problems, then schedule a repeat eye exam before kindergarten.

As myopia runs in families, if your child has family members with vision issues, it’s even more important to test their eyes early. If you or your pediatrician notice any vision issues, your child may be referred to an optometrist or pediatric ophthalmologist.

During a children’s eye exam, your eye care provider will do a physical examination of your child’s eyes and check for a regular light reflex. For children between the ages of 3 and 5 years, your provider will also conduct vision screenings using eye chart tests, pictures, letters or the “tumbling E game,” also called the “Random E’s Visual Acuity Test.”

As your child’s vision continues to change as they grow, continue to make sure they get vision screenings by their pediatrician or eye care provider before first grade and every two years thereafter. While most schools conduct eye screenings, they’re usually not complete enough to diagnose myopia. Providers diagnose most children when they’re between the ages of 3 and 12.

Your provider may mention categories — mild, moderate or high myopia. These terms refer to the degree of nearsightedness as measured by refractive error. Refractive errors are issues with the natural shape of your eyes that make your vision blurry. It’s possible to have myopia and another refractive error, like astigmatism.

Management and Treatment:

How is myopia treated?

Glasses or contact lenses can correct myopia in children and adults. For adults only (with rare exceptions for children), there are several types of refractive surgeries that can also correct myopia.

With myopia, your prescription for glasses or contact lenses is a negative number, such as -3.00. The higher the number, the stronger your lenses will be. The prescription helps your eye focus light on your retina, clearing up your distance vision.

* Eyeglasses: The most popular way for most people to correct myopia is with eyeglasses. Depending on the degree of vision correction needed, you’ll wear eyeglasses either daily or only when you need distance vision. You may only need glasses for driving. Some kids with myopia may only need glasses to play ball, watch a movie or view the chalkboard. Some people may need to wear glasses constantly to see clearly. A single-vision lens will make distance vision clearer. But people over 40 who have myopia may require a bifocal or progressive lens to see clearly both near and far.
* Contact lenses: Some people find that their distance vision is sharper and wider with contact lenses. A potential downside is they require more care to keep clean. Ask your provider which type might be right for your myopia level and other refractive errors.
* Ortho-k or CRT: Some people with mild myopia may be candidates for temporary corneal refractive contact lenses that you wear to bed to reshape your cornea temporarily, long enough to see for your daily activities.
* LASIK is a laser-assisted in situ keratomileus procedure, the most common surgery to correct nearsightedness. In a LASIK procedure, your ophthalmologist uses a laser to cut a flap through the top of your cornea, reshape the inner corneal tissue and then drop the flap back into place.
* LASEK is a laser-assisted subepithelial keratectomy procedure. In a LASEK procedure, your ophthalmologist uses a laser to cut a flap through only the top layer (epithelium) of your cornea, reshape the outer layers, and then close the flap.
* PRK is short for “photorefractive keratectomy,” which is a type of laser eye surgery used to correct mild or moderate nearsightedness. It may also correct farsightedness and/or astigmatism. In a PRK procedure, your ophthalmologist cuts off the front surface of your cornea and uses a laser to reshape the surface, which flattens it and allows light rays to focus on your retina. Unlike LASIK, the ophthalmologist doesn’t cut a flap, and your cornea will regrow its top layer in one to two weeks. PRK is better for people with corneas that are thinner or have a rough surface because it disrupts less corneal tissue than a comparable LASIK surgery.
* Phakic intraocular lenses: These are an option for people who have high myopia or whose corneas are too thin for PRK or LASIK. Your provider places phakic intraocular lenses inside of your eye just in front of your natural lens.
* Intraocular lens implant: This allows your ophthalmologist to surgically insert a new lens in your eye, replacing your natural one. This procedure happens before a cataract develops.
* Vision therapy: This is an option if spasms of your focusing muscles cause myopia. You can strengthen the muscles through eye exercises and improve your focus. This treatment isn’t appropriate for everyone with myopia. After an eye exam, your ophthalmologist will let you know if it’s an option for you.

Outlook / Prognosis:

What can I expect if I have myopia?

Myopia is a condition that doesn’t go away. Treatments include using glasses or contact lenses. You may be able to get surgery to correct your vision.

What is the outlook for myopia?

The outlook for being nearsighted may differ depending on the type of myopia.

Usually, providers can treat simple myopia easily. In rare cases of high myopia or pathologic myopia, your outlook may be different.

High myopia usually stops getting worse between the ages of 20 and 30. You’ll still be able to get glasses or contact lenses or you may be able to have surgery.

High myopia may lead to pathologic myopia and the possibility of more serious sight conditions later in life. These complications can lead to loss of sight.

Regular eye exams are important for everyone but are especially if you have high myopia or pathologic myopia. You should follow the schedule set out by your eye care provider.

Prevention:

Can myopia be prevented?

You can’t prevent myopia as it’s a condition that tends to run in families, but you may be able to lower your risk of nearsightedness in some ways.

How can I lower my risk of developing myopia?

Some eye experts believe that you may be able to decrease your or your child’s risk of developing myopia by getting enough time outside and limiting the amount of time spent in front of screens. You may also want to be mindful of the amount of time doing close work like reading or sewing.

Additional Information

Myopia occurs if the eyeball is too long or the cornea (the clear front cover of the eye) is too curved. As a result, the light entering the eye isn't focused correctly, and distant objects look blurred. Myopia affects nearly 30% of the U.S. population. While the exact cause of myopia is unknown, there is significant evidence that many people inherit myopia, or at least the tendency to develop myopia. If one or both parents are nearsighted, there is an increased chance their children will be nearsighted. Even though the tendency to develop myopia may be inherited, its actual development may be affected by how a person uses his or her eyes. Individuals who spend considerable time reading, working at a computer, playing video games or doing other intense close visual work may be more likely to develop myopia. In fact, high levels of screen time on smart devices (i.e. looking at a smart phone) is associated with around a 30% higher risk of myopia and, when combined with excessive computer use, that risk rose to around 80%.

Causes & risk factors

Myopia may also occur due to environmental factors or other health problems:

* Some people may experience blurred distance vision only at night. With "night myopia," low light makes it difficult for the eyes to focus properly. Or the increased pupil size during dark conditions allows more peripheral, unfocused light rays to enter the eye.
* People who do an excessive amount of near-vision work may experience a false or "pseudo" myopia. Their blurred distance vision is caused by overuse of the eyes' focusing mechanism. After long periods of near work, their eyes are unable to refocus to see clearly in the distance. Clear distance vision usually returns after resting the eyes. However, constant visual stress may lead to a permanent reduction in distance vision over time.
* Symptoms of myopia may also be a sign of variations in blood sugar levels in people with diabetes or maybe an early indication of a developing cataract.

Symptoms

People with myopia can have difficulty clearly seeing a movie or TV screen, a whiteboard in school or while driving. Generally, myopia first occurs in school-age children. Because the eye continues to grow during childhood, it typically progresses until about age 20. However, myopia may also develop in adults due to visual stress or health conditions such as diabetes.

Diagnosis

Testing for myopia may use several procedures to measure how the eyes focus light and to determine the power of any optical lenses needed to correct the reduced vision. As part of the testing, you will identify letters on a distance chart. This test measures visual acuity, which is written as a fraction, such as 20/40. The top number of the fraction is the standard distance at which testing is performed (20 feet). The bottom number is the smallest letter size read. A person with 20/40 visual acuity would have to get within 20 feet to identify a letter that could be seen clearly at 40 feet in a "normal" eye. Normal distance visual acuity is 20/20, although many people have 20/15 (better) vision.

Using an instrument called a phoropter, a doctor of optometry places a series of lenses in front of your eyes and measures how they focus light using a handheld lighted instrument called a retinoscope. Or the doctor may choose to use an automated instrument that evaluates the focusing power of the eye. The power is then refined based on your responses to determine the lenses that allow the clearest vision. Your doctor can conduct this testing without using eye drops to determine how the eyes respond under normal seeing conditions.

In some cases, such as for patients who can't respond verbally or when some of the eye's focusing power may be hidden, a doctor may use eye drops. The eye drops temporarily keep the eyes from changing focus during testing. Using the information from these tests, along with the results of other tests of eye focusing and eye teaming, your doctor can determine if you have myopia. He or she will also determine the power of any lens correction needed to provide a clearer vision. Once testing is complete, your doctor can discuss treatment options.

Treatment

People with myopia have several options available to regain clear distance vision. They include:

* Eyeglasses. For most people with myopia, eyeglasses are the primary choice for correction. Depending on the amount of myopia, you may only need to wear glasses for certain activities, like watching a movie or driving a car. Or, if you are very nearsighted, you may need to wear them all the time. Generally, a single-vision lens is prescribed to provide clear vision at all distances. However, patients over age 40, or children and adults whose myopia is due to the stress of near vision work, may need a bifocal or progressive addition lens. These multifocal lenses provide different powers or strengths throughout the lens to allow for clear vision in the distance and up close.
* Contact lenses. For some individuals, contact lenses offer clearer vision and a wider field of view than eyeglasses. However, since contact lenses are worn directly on the eyes, they require proper evaluation and care to safeguard eye health.
* Ortho-k or CRT. Another option for treating myopia is orthokeratology (ortho-k), also known as corneal refractive therapy (CRT). In this nonsurgical procedure, you wear a series of specially designed rigid contact lenses to gradually reshape the curvature of your cornea, the front outer surface of the eye. The lenses place pressure on the cornea to flatten it. This changes how light entering the eye is focused. You wear the contact lenses for limited periods, such as overnight, and then remove them. People with mild myopia may be able to temporarily obtain clear vision for most of their daily activities.
* Laser procedures. Laser procedures such as LASIK (laser in situ keratomileusis) or PRK (photorefractive keratectomy) are also possible treatment options for myopia in adults. A laser beam of light reshapes the cornea by removing a small amount of corneal tissue. The amount of myopia that PRK or LASIK can correct is limited by the amount of corneal tissue that can be safely removed. In PRK, a laser removes a thin layer of tissue from the surface of the cornea in order to change its shape and refocus light entering the eye. LASIK removes tissue from the inner layers, but not from the surface, of the cornea. To do this, a section of the outer corneal surface is lifted and folded back to expose the inner tissue. A laser then removes the precise amount of corneal tissue needed to reshape the eye. Then, the flap of outer tissue is placed back in position to heal.
* Other refractive surgery procedures. People who are highly nearsighted or whose corneas are too thin for laser procedures may be able to have their myopia surgically corrected. A doctor may be able to implant small lenses with the desired optical correction in their eyes. The implant can be placed just in front of the natural lens (phakic intraocular lens implant), or the implant can replace the natural lens (clear lens extraction with intraocular lens implantation). This clear lens extraction procedure is similar to cataract surgery but occurs before a cataract is present.
* Vision therapy for people with stress-related myopia. Vision therapy is an option for people whose blurred distance vision is caused by a spasm of the muscles that control eye focusing. Various eye exercises can improve poor eye focusing ability and regain clear distance vision.

People with myopia have a variety of options to correct vision problems. A doctor of optometry will help select the treatment that best meets the visual and lifestyle needs of the patient.

Prevention

Children who are at high risk of progressive myopia (family history, early age of onset, and extended periods of near work) may benefit from treatment options that have been shown to reduce the progression of myopia. These treatments include the prescription of bifocal spectacle or contact lenses, orthokeratology, eye drops, or a combination of these. Because persons with high myopia are at a greater risk of developing cataracts, glaucoma and myopic macular degeneration, myopia management may help preserve eye health.

Jai Ganesh · Jokes

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A: You've got appeal in bunches!
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Q: What's the new definition of divine?
A: It's what da grapes grow on.
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Q: What did the green grape say to the purple grape?
A: Breathe idoit breathe.
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Q: Why did the grape stop in the middle of the road?
A: Because he ran out of juice.
* * *
Q: Why'd Mrs Grape leave her family?
A: She was tired of raisin kids!
* * *

Jai Ganesh · Jai Ganesh's Puzzles

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Jai Ganesh · Dark Discussions at Cafe Infinity

2434) Tsung-Dao Lee

Gist:

Work

For a long time, physicists assumed that various symmetries characterized nature. In a kind of “mirror world” where right and left were reversed and matter was replaced by antimatter, the same physical laws would apply, they posited. The equality of these laws was questioned concerning the decay of certain elementary particles, however, in 1956 and Tsung-Dao Lee and Chen Ning Yang formulated a theory that the left-right symmetry law is violated by the weak interaction. Measurements of electrons’ direction of motion during a cobalt isotope’s beta decay confirmed this.

Summary

Tsung-Dao Lee (born November 24, 1926, Shanghai, China—died August 4, 2024, San Francisco, California, U.S.) was a Chinese-born American physicist who, with Chen Ning Yang, received the Nobel Prize for Physics in 1957 for work in discovering violations of the principle of parity conservation (the quality of space reflection symmetry of subatomic particle interactions), thus bringing about major refinements in particle physics theory.

In 1946 Lee was awarded a scholarship to study in the United States, and, although he had no undergraduate degree, he entered the graduate school in physics at the University of Chicago, where Enrico Fermi selected him as a doctoral student. After working briefly at the University of Chicago’s Yerkes Astronomical Observatory in Wisconsin, the University of California at Berkeley, and for two years with Yang at the Institute for Advanced Study, Princeton, New Jersey, Lee was appointed assistant professor of physics at Columbia University in 1953.

In 1956 Lee and Yang concluded that the theta-meson and tau-meson, previously thought to be different because they decay by modes of differing parity, are in fact the same particle (now called the K-meson). Because the law of parity conservation prohibits a single particle from having decay modes exhibiting opposite parity, the only possible conclusion was that, for weak interactions at least, parity is not conserved. They suggested experiments to test their hypothesis, and in 1956–57 Chien-Shiung Wu, working at Columbia University, experimentally confirmed their theoretical conclusions.

In 1960 Lee was appointed professor of physics at the Institute for Advanced Study, and three years later he returned to Columbia to assume the first Enrico Fermi professorship in physics; he retired as professor emeritus in 2012. Beginning in 1964, he made important contributions to the explanation of the violations of time-reversal invariance, which occur during certain weak interactions.

Details

Tsung-Dao Lee (November 24, 1926 – August 4, 2024) was a Chinese-American physicist known for his work on parity violation, the Lee–Yang theorem, particle physics, relativistic heavy ion (RHIC) physics, nontopological solitons, and soliton stars. He was a university professor emeritus at Columbia University in New York City, where he taught from 1953 until his retirement in 2012.

In 1957, at the age of 30, Lee won the Nobel Prize in Physics with Chen Ning Yang for their work on the violation of the parity law in weak interactions, which Chien-Shiung Wu experimentally proved from 1956 to 1957, with her well known Wu experiment.

Lee remains the youngest Nobel laureate in the science fields after World War II. He is the third-youngest Nobel laureate in sciences in history after William L. Bragg (who won the prize at 25 with his father William H. Bragg in 1915) and Werner Heisenberg (who won in 1932 also at 30). Lee and Yang were the first Chinese laureates. Since he became a naturalized American citizen in 1963, Lee is also the youngest American ever to have won a Nobel Prize.

Biography:

Family

Lee was born in Shanghai, China, with his ancestral home in nearby Suzhou. His father Chun-kang Lee, one of the first graduates of the University of Nanking, was a chemical industrialist and merchant who was involved in China's early development of modern synthesized fertilizer. Lee's grandfather Chong-tan Lee was the first Chinese Methodist Episcopal senior pastor of St. John's Church in Suzhou [zh].

Lee had four brothers and one sister. Educator Robert C. T. Lee was one of T. D.'s brothers. Lee's mother Chang and brother Robert C. T. moved to Taiwan in the 1950s.

Early life

Lee received his secondary education in Shanghai (High School Affiliated to Soochow University) and Jiangxi (Jiangxi Joint High School). Due to the Second Sino-Japanese War, Lee's high school education was interrupted, thus he did not obtain his secondary diploma. Nevertheless, in 1943, Lee directly applied to and was admitted by the National Chekiang University (now Zhejiang University). Initially, Lee registered as a student in the Department of Chemical Engineering. Very quickly, Lee's talent was discovered and his interest in physics grew rapidly. Several physics professors, including Shu Xingbei and Wang Ganchang, largely guided Lee, and he soon transferred into the Department of Physics of National Che Kiang University, where he studied in 1943–1944.

However, again disrupted by a further Japanese invasion, Lee continued at the National Southwestern Associated University in Kunming the next year in 1945, where he studied with Professor Wu Ta-You.

Life and research in the U.S.

Professor Wu nominated Lee for a Chinese government fellowship for graduate study in the United States. In 1946, Lee went to the University of Chicago and was selected by Professor Enrico Fermi to become his PhD student. Lee received his PhD under Fermi in 1950 for his research work Hydrogen Content of White Dwarf Stars. Lee served as research associate and lecturer in physics at the University of California at Berkeley from 1950 to 1951.

In 1953, Lee joined Columbia University, where he remained until retirement. His first work at Columbia was on a solvable model of quantum field theory better known as the Lee model. Soon, his focus turned to particle physics and the developing puzzle of K meson decays. Lee realized in early 1956 that the key to the puzzle was parity non-conservation. At Lee's suggestion, the first experimental test was on hyperon decay by the Steinberger group. At that time, the experimental result gave only an indication of a 2 standard deviation effect of possible parity violation. Encouraged by this feasibility study, Lee made a systematic study of possible Time reversal (T), Parity (P), Charge Conjugation (C), and CP violations in weak interactions with collaborators, including C. N. Yang. After the definitive experimental confirmation by Chien-Shiung Wu and her assistants that showed that parity was not conserved, Lee and Yang were awarded the 1957 Nobel Prize in Physics. Wu was not awarded the Nobel prize, which is considered a notable controversy in Nobel committee history.

In the early 1960s, Lee and collaborators initiated the important field of high-energy neutrino physics. In 1964, Lee, with M. Nauenberg, analyzed the divergences connected with particles of zero rest mass, and described a general method known as the KLN theorem for dealing with these divergences, which still plays an important role in contemporary work in QCD, with its massless, self-interacting gluons. In 1974–75, Lee published several papers on "A New Form of Matter in High Density", which led to the modern field of RHIC physics, now dominating the entire high-energy nuclear physics field.

Besides particle physics, Lee was active in statistical mechanics, astrophysics, hydrodynamics, many body system, solid state, and lattice QCD. In 1983, Lee wrote a paper entitled, "Can Time Be a Discrete Dynamical Variable?"; which led to a series of publications by Lee and collaborators on the formulation of fundamental physics in terms of difference equations, but with exact invariance under continuous groups of translational and rotational transformations. Beginning in 1975, Lee and collaborators established the field of non-topological solitons, which led to his work on soliton stars and black holes throughout the 1980s and 1990s.

From 1997 to 2003, Lee was director of the RIKEN-BNL Research Center (now director emeritus), which together with other researchers from Columbia, completed a 1 teraflops supercomputer QCDSP for lattice QCD in 1998 and a 10 teraflops QCDOC machine in 2001. Leading up to 2005, Lee and Richard M. Friedberg developed a new method to solve the Schrödinger equation, leading to convergent iterative solutions for the long-standing quantum degenerate double-wall potential and other instanton problems. They also did work on the neutrino mapping matrix.

Lee was one of the 20 American recipients of the Nobel Prize in Physics to sign a letter addressed to President George W. Bush in May 2008, urging him to "reverse the damage done to basic science research in the Fiscal Year 2008 Omnibus Appropriations Bill" by requesting additional emergency funding for the Department of Energy's Office of Science, the National Science Foundation, and the National Institute of Standards and Technology.

Educational activities

Soon after the re-establishment of China-American relations with the PRC, Lee and his wife, Jeannette Hui-Chun Chin, were able to go to the PRC, where Lee gave a series of lectures and seminars, and organized the CUSPEA (China-U.S. Physics Examination and Application).

In 1998, Lee established the Chun-Tsung Endowment ) in memory of his wife, who had died three years earlier. The Chun-Tsung scholarships, supervised by the United Board for Christian Higher Education in Asia (New York), are awarded to undergraduates, usually in their 2nd or 3rd year, at six universities, which are Shanghai Jiaotong University, Fudan University, Lanzhou University, Soochow University, Peking University, and Tsinghua University. Students selected for such scholarships are named "Chun-Tsung Scholars".

Personal life and death

Lee and Jeannette Hui-Chun Chin married in 1950 and had two sons: James Lee and Stephen Lee. His wife died in 1996. James donated his father's Nobel Prize medal to Shanghai Jiao Tong University in 2014 where it is on display in the Tsung-Dao Lee Library.

Tsung-Dao Lee died in San Francisco on August 4, 2024, at the age of 97.

Jai Ganesh · This is Cool

Nervous System

Gist

The nervous system is the body's primary command center, controlling actions, sensory information, and involuntary functions by transmitting electrical signals between the brain, spinal cord, and body. Divided into the central (brain/spinal cord) and peripheral (nerves) systems, it enables movement, thought, memory, and, together with the endocrine system, maintains homeostasis.

Core Components

Central Nervous System (CNS): Comprises the brain and spinal cord, which act as the main processing center for information.
Peripheral Nervous System (PNS): Consists of all nerves outside the brain and spinal cord, connecting the CNS to limbs and organs.
Neurons: The basic structural units (nerve cells) that send messages via electrical impulses, featuring axons for transmission and dendrites for reception.

Summary

In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. Nervous tissue first arose in wormlike organisms about 550 to 600 million years ago. In vertebrates, it consists of two main parts, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves, which are enclosed bundles of the long fibers, or axons, that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor nerves (efferent), while those nerves that transmit information from the body to the CNS are called sensory nerves (afferent). The PNS is divided into two separate subsystems, the somatic and autonomic nervous systems. The autonomic nervous system is further subdivided into the sympathetic, parasympathetic and enteric nervous systems. The sympathetic nervous system is activated in cases of emergencies to mobilize energy, while the parasympathetic nervous system is activated when organisms are in a relaxed state. The enteric nervous system functions to control the gastrointestinal system. Nerves that exit from the brain are called cranial nerves while those exiting from the spinal cord are called spinal nerves.

The nervous system consists of nervous tissue which, at a cellular level, is defined by the presence of a special type of cell, called the neuron. Neurons have special structures that allow them to send signals rapidly and precisely to other cells. They send these signals in the form of electrochemical impulses traveling along thin fibers called axons, which can be directly transmitted to neighboring cells through electrical synapses or cause chemicals called neurotransmitters to be released at chemical synapses. A cell that receives a synaptic signal from a neuron may be excited, inhibited, or otherwise modulated. The connections between neurons can form neural pathways, neural circuits, and larger networks that generate an organism's perception of the world and determine its behavior. Along with neurons, the nervous system contains other specialized cells called glial cells (or simply glia), which provide structural and metabolic support. Many of the cells and vasculature channels within the nervous system make up the neurovascular unit, which regulates cerebral blood flow in order to rapidly satisfy the high energy demands of activated neurons.

Nervous systems are found in most multicellular animals, but vary greatly in complexity. The only multicellular animals that have no nervous system at all are sponges, placozoans, and mesozoans, which have very simple body plans. The nervous systems of the radially symmetric organisms ctenophores (comb jellies) and cnidarians (which include anemones, hydras, corals and jellyfish) consist of a diffuse nerve net. All other animal species, with the exception of a few types of worm, have a nervous system containing a brain, a central cord (or two cords running in parallel), and nerves radiating from the brain and central cord. The size of the nervous system ranges from a few hundred cells in the simplest worms, to around 300 billion cells in African elephants.

The central nervous system functions to send signals from one cell to others, or from one part of the body to others and to receive feedback. Malfunction of the nervous system can occur as a result of genetic defects, physical damage due to trauma or toxicity, infection, or simply senescence. The medical specialty of neurology studies disorders of the nervous system and looks for interventions that can prevent or treat them. In the peripheral nervous system, the most common problem is the failure of nerve conduction, which can be due to different causes including diabetic neuropathy and demyelinating disorders such as multiple sclerosis and amyotrophic lateral sclerosis. Neuroscience is the field of science that focuses on the study of the nervous system.

Details

Your nervous system plays a role in everything you do. The three main parts of your nervous system are your brain, spinal cord and nerves. It helps you move, think and feel. It even regulates the things you do but don’t think about like digestion. It contains the central nervous system and the peripheral nervous system.

Overview:

What is the nervous system?

Your nervous system is your body’s command center. It’s made up of your brain, spinal cord and nerves. Your nervous system works by sending messages, or electrical signals, between your brain and all the other parts of your body. These signals tell you to breathe, move, speak and see, for example. Your nervous system keeps track of what’s going on inside and outside of your body and decides how to respond to any situation you’re in.

Your nervous system regulates complicated processes like thoughts and memory. It also plays an essential role in the things your body does without thinking, like blushing, sweating and blinking.

Function:

What does the nervous system do?

Your nervous system’s main function is to send messages from various parts of your body to your brain, and from your brain back out to your body to tell your body what to do. These messages regulate your:

* Thoughts, memory, learning and feelings.
* Movements (balance and coordination).
* Senses (how your brain interprets what you see, hear, taste, touch and feel).
* Wound healing.
* Sleep.
* Heartbeat and breathing patterns.
* Response to stressful situations, including sweat production.
* Digestion.
* Body processes, such as puberty and aging.

How does the nervous system work?

Your nervous system uses nerve cells called neurons to send signals, or messages, all over your body. These electrical signals travel among your brain, skin, organs, glands and muscles.

The messages help you move your limbs and feel sensations, like pain. Your eyes, ears, tongue, nose and the nerves all over your body take in information about your environment. Then, nerves carry that data to and from your brain.

There are different types of neurons. Each type of neuron has a different job:

* Motor neurons take signals from your brain and spinal cord to your muscles. They help you move. They also assist with breathing, swallowing and speaking.
* Sensory neurons take information from your senses (what you see, touch, taste, etc.) to your brain.
* Interneurons communicate between motor and sensory neurons. These neurons regulate your movement in response to sensory information (like moving away from a hot surface) and play a role in how you learn, think and remember.

Anatomy:

What are the parts of the nervous system?

The nervous system has two main parts:

* Central nervous system (CNS): Your brain and spinal cord make up your CNS. Your brain reads signals from your nerves to regulate how you think, move and feel.
* Peripheral nervous system (PNS): Your PNS is made up of a network of nerves. The nerves branch out from your spinal cord. This system relays information from your brain and spinal cord to your organs, arms, legs, fingers and toes.

There are two parts to your peripheral nervous system:

*The somatic nervous system guides your voluntary movements.
* The autonomic nervous system regulates the activities you do without thinking about them (involuntary movements).

What does the nervous system look like?

Nerve cells (neurons) are the basis of your nervous system. There are 100 billion neurons in your brain. These cells connect throughout your entire body.

Imagine your nervous system as a tree. Your central nervous system is the trunk of the tree that contains your brain and spinal cord. The tree branches are your peripheral nervous system (nerves). The branches extend from the truck (brain and spinal cord) to reach all parts of your body.

Conditions and Disorders:

What are common conditions or disorders that affect the nervous system?

There are many conditions that affect your nervous system. Some of the most common include:

* Alzheimer’s disease.
* Cancer.
* Cerebral palsy.
* Epilepsy.
* Huntington’s disease.
* Infection (meningitis).
* Parkinson’s disease.
* Stroke.
* Traumatic brain injury.

What are common signs or symptoms of nervous system conditions?

Signs and symptoms of nervous system conditions vary by type but may include:

* Movement and coordination changes.
* Memory loss.
* Pain, numbness or a pins and needles feeling.
* Behavioral and mood changes.
* Difficulty with thinking and reasoning.
* Seizures.

Some conditions, like a stroke, are medical emergencies that need treatment quickly. If you notice the following symptoms, contact 911 or your local emergency services number:

* Muscle weakness or paralysis in one side of your body.
* Sudden vision loss.
* Slurred speech.
* Confusion.

What tests check the health of your nervous system?

A healthcare provider may use one of the following tests to check the health of your nervous system:

* Computed tomography (CT) scan.
* Electrocardiogram (ECG or EKG).
* Electroencephalogram (EEG).
* Lumbar puncture (spinal tap).
* Magnetic resonance imaging (MRI) scans.

How are conditions that affect the nervous system treated?

A healthcare provider will review your symptoms to diagnose and treat any conditions that affect your nervous system. Treatment varies for each condition. So, your healthcare provider will take into consideration several factors, like your age and general health, to create your treatment plan. This plan may include:

* Taking medications.
* Having surgery.
* Participating in counseling for mental and emotional support.
* Receiving supportive care (to keep you comfortable).

Additional Information:

Key Facts

* The nervous system is made up of the brain, spinal cord and nerves.
* The nervous system is responsible for intelligence, learning, memory, movement, the senses and basic body functions such as your heartbeat and breathing.
* The basic building blocks of the nervous system are the nerve cells (neurons) which are responsible for carrying messages to and from different parts of the body.
* The brain is in constant communication with all parts of the body, sending instructions and receiving input from the senses.

What is the nervous system?

The nervous system is made up of the brain, spinal cord and nerves.

It controls many aspects of what you think, how you feel and what your body does. It allows you to do things such as walk, speak, swallow, breathe and learn. It also controls how the body reacts in stressful situations. The nervous system interprets and responds to information gathered through the senses.

What is function of the nervous system?

The main function of the nervous system is to be the body's communication network. Its main job is to send and receive messages between you and the outside world, and within your own body.

The nervous system is responsible for:

* intelligence, learning and memory: your thoughts and feelings
* physical movement
* basic body functions such as the beating of your heart, breathing, digestion, sweating and shivering
* the senses: sight, hearing, taste, touch and smell

What are the parts of the nervous system?

The nervous system is made up of:

* the central nervous system (CNS), which consists of the brain and spinal cord
* the peripheral nervous system (PNS), which consists of nerves that connect the CNS to the rest of the body

The brain is made up of different parts. These include the:

* cerebrum
* cerebellum
* thalamus
* hypothalamus
* brainstem

The brain's cerebral cortex is the outermost layer of the brain that gives the brain its wrinkly appearance. The cerebral cortex is divided in half lengthways into two sides or hemispheres, the left hemisphere, and the right hemisphere. Each hemisphere specialises in different functions, but they share information and work together seamlessly.

Each brain hemisphere (parts of the cerebrum) has 4 different sections called lobes. These lobes are the frontal, parietal, temporal and occipital lobes. Each lobe carries out different brain functions.

Learn more about the structure of the central nervous system and how it works.

What are nerve cells?

The basic building blocks of the nervous system are the nerve cells, or neurons. The human brain has around 100 billion neurons. These cells are responsible for carrying messages to and from different parts of the body.

Neurons have a cell body which contain the cell's nucleus as well as special extension called dendrites and axons.

The synapse is the gap between the end of one neuron's axon and the tip of next neuron's dendrites. Messages travel from one neuron to the next across synapses.

A neuron and it's parts.

How does the nervous system work?

The brain is in constant communication with all parts of the body, sending instructions and receiving input from the senses.

Outgoing messages from the brain are sent along motor pathways, which carry messages from the brain to the muscles to tell them to move. The neurons that make up these motor pathways are called motor neurons.

Incoming messages from the body to the brain are sent along sensory pathways. The sensory pathways detect things such as light and sound and carry information about these to the brain. The neurons that make up these sensory pathways are called sensory neurons.

The spinal cord carries motor and sensory signals between the brain and nerves. The spinal cord also contains separate circuits for many reflexes.

One part of the nervous system, called the autonomic nervous system, controls a lot of the body processes that function automatically, for example, breathing, sweating or shivering.

There are 2 parts to the autonomic nervous system:

* the sympathetic nervous system, which controls how you respond in an emergency or when you are under stress (for example, it makes your heart beat faster and causes you to release adrenaline)
* the parasympathetic nervous system, which prepares the body for rest

These parts work together to manage how the body responds to your changing environment and needs. For example, your pupils change size to allow the right amount of light into your eyes to allow effective vision.

What medical conditions are related to the nervous system?

There are thousands of conditions that start in or affect the central nervous system, including:

* degenerative conditions such as Parkinson's disease, Alzheimer's disease and multiple sclerosis
* stroke
* seizure disorders, such as epilepsy
* cancer, such as brain tumours
* infections, such as meningitis
* brain injuries and spinal cord injuries
* spinal cord compression (spinal stenosis)

What are the symptoms of problems with the nervous system?

There are many different symptoms that could suggest a problem with the nervous system. They include:

* headaches
* blurry vision
* fatigue
* leg or arm numbness
* loss of coordination, weakness or loss of muscle strength
* slurred speech
* tremors

Other symptoms that might suggest a problem with the central nervous system include:

* emotional problems
* memory loss
* behavioural changes

There are also many diseases that affect the peripheral nervous system. The peripheral nerves include the nerves outside the brain and spinal cord such as nerves of the face, arms, legs and torso. Read more on diseases of the peripheral nervous system.

Jai Ganesh · This is Cool

2496) Oceanography

Gist

Oceanography, or marine science, is the interdisciplinary study of the world's oceans, covering 70% of Earth's surface. It integrates biology, chemistry, physics, and geology to examine marine life, ocean currents, seafloor structure, and chemical properties. Key branches include physical, chemical, geological, and biological oceanography, which are vital for understanding climate regulation, marine ecosystems, and resources.

Oceanography is the interdisciplinary study of the ocean, covering its physical, chemical, biological, and geological aspects, from marine life and currents to seafloor geology and its role in climate. It combines fields like biology, chemistry, physics, and geology to understand ocean processes, ecosystems, and the impact of human activities, using tools like research vessels, underwater vehicles, and satellites to explore the 70% of Earth covered by water.

Summary

Oceanography is a scientific discipline concerned with all aspects of the world’s oceans and seas, including their physical and chemical properties, their origin and geologic framework, and the life forms that inhabit the marine environment.

A brief treatment of oceanography follows.

Traditionally, oceanography has been divided into four separate but related branches: physical oceanography, chemical oceanography, marine geology, and marine ecology. Physical oceanography deals with the properties of seawater (temperature, density, pressure, and so on), its movement (waves, currents, and tides), and the interactions between the ocean waters and the atmosphere. Chemical oceanography has to do with the composition of seawater and the biogeochemical cycles that affect it. Marine geology focuses on the structure, features, and evolution of the ocean basins. Marine ecology, also called biological oceanography, involves the study of the plants and animals of the sea, including life cycles and food production.

Oceanography is the sum of these several branches. Oceanographic research entails the sampling of seawater and marine life for close study, the remote sensing of oceanic processes with aircraft and Earth-orbiting satellites, and the exploration of the seafloor by means of deep-sea drilling and seismic profiling of the terrestrial crust below the ocean bottom. Greater knowledge of the world’s oceans enables scientists to more accurately predict, for example, long-term weather and climatic changes and also leads to more efficient exploitation of the Earth’s resources. Oceanography also is vital to understanding the effect of pollutants on ocean waters and to the preservation of the quality of the oceans’ waters in the face of increasing human demands made on them.

Details

Oceanography, also known as oceanology, sea science, ocean science, and marine science, is the scientific study of the ocean, including its physics, chemistry, biology, and geology.

It is an Earth science, which covers a wide range of topics, including ocean currents, waves, and geophysical fluid dynamics; fluxes of various chemical substances and physical properties within the ocean and across its boundaries; ecosystem dynamics; and plate tectonics and seabed geology.

Oceanographers draw upon a wide range of disciplines to deepen their understanding of the world’s oceans, incorporating insights from astronomy, biology, chemistry, geography, geology, hydrology, meteorology and physics.

Modern oceanography

Knowledge of the oceans remained confined to the topmost few fathoms of the water and a small amount of the bottom, mainly in shallow areas. Almost nothing was known of the ocean depths. The British Royal Navy's efforts to chart all of the world's coastlines in the mid-19th century reinforced the vague idea that most of the ocean was very deep, although little more was known. As exploration ignited both popular and scientific interest in the polar regions and Africa, so too did the mysteries of the unexplored oceans.

The seminal event in the founding of the modern science of oceanography was the 1872–1876 Challenger expedition. As the first true oceanographic cruise, this expedition laid the groundwork for an entire academic and research discipline. In response to a recommendation from the Royal Society, the British Government announced in 1871 an expedition to explore world's oceans and conduct appropriate scientific investigation. Charles Wyville Thomson and Sir John Murray launched the Challenger expedition. Challenger, leased from the Royal Navy, was modified for scientific work and equipped with separate laboratories for natural history and chemistry. Under the scientific supervision of Thomson, Challenger travelled nearly 70,000 nautical miles (130,000 km) surveying and exploring. On her journey circumnavigating the globe, 492 deep sea soundings, 133 bottom dredges, 151 open water trawls and 263 serial water temperature observations were taken. Around 4,700 new species of marine life were discovered. The result was the Report Of The Scientific Results of the Exploring Voyage of H.M.S. Challenger during the years 1873–76. Murray, who supervised the publication, described the report as "the greatest advance in the knowledge of our planet since the celebrated discoveries of the fifteenth and sixteenth centuries". He went on to found the academic discipline of oceanography at the University of Edinburgh, which remained the centre for oceanographic research well into the 20th century. Murray was the first to study marine trenches and in particular the Mid-Atlantic Ridge, and map the sedimentary deposits in the oceans. He tried to map out the world's ocean currents based on salinity and temperature observations, and was the first to correctly understand the nature of coral reef development.

In the late 19th century, other Western nations also sent out scientific expeditions (as did private individuals and institutions). The first purpose-built oceanographic ship, Albatros, was built in 1882. In 1893, Fridtjof Nansen allowed his ship, Fram, to be frozen in the Arctic ice. This enabled him to obtain oceanographic, meteorological and astronomical data at a stationary spot over an extended period.

In 1881 the geographer John Francon Williams published a seminal book, Geography of the Oceans. Between 1907 and 1911 Otto Krümmel published the Handbuch der Ozeanographie, which became influential in awakening public interest in oceanography. The four-month 1910 North Atlantic expedition headed by John Murray and Johan Hjort was the most ambitious research oceanographic and marine zoological project ever mounted until then, and led to the classic 1912 book The Depths of the Ocean.

The first acoustic measurement of sea depth was made in 1914. Between 1925 and 1927 the "Meteor" expedition gathered 70,000 ocean depth measurements using an echo sounder, surveying the Mid-Atlantic Ridge.

In 1934, Easter Ellen Cupp, the first woman to have earned a PhD (at Scripps) in the United States, completed a major work on diatoms that remained the standard taxonomy in the field until well after her death in 1999. In 1940, Cupp was let go from her position at Scripps. Sverdrup specifically commended Cupp as a conscientious and industrious worker and commented that his decision was no reflection on her ability as a scientist. Sverdrup used the instructor billet vacated by Cupp to employ Marston Sargent, a biologist studying marine algae, which was not a new research program at Scripps. Financial pressures did not prevent Sverdrup from retaining the services of two other young post-doctoral students, Walter Munk and Roger Revelle. Cupp's partner, Dorothy Rosenbury, found her a position teaching high school, where she remained for the rest of her career.

Sverdrup, Johnson and Fleming published The Oceans in 1942, which was a major landmark. The Sea (in three volumes, covering physical oceanography, seawater and geology) edited by M.N. Hill was published in 1962, while Rhodes Fairbridge's Encyclopedia of Oceanography was published in 1966.

The Great Global Rift, running along the Mid Atlantic Ridge, was discovered by Maurice Ewing and Bruce Heezen in 1953 and mapped by Heezen and Marie Tharp using bathymetric data; in 1954 a mountain range under the Arctic Ocean was found by the Arctic Institute of the USSR. The theory of seafloor spreading was developed in 1960 by Harry Hammond Hess. The Ocean Drilling Program started in 1966. Deep-sea vents were discovered in 1977 by Jack Corliss and Robert Ballard in the submersible DSV Alvin.

In the 1950s, Auguste Piccard invented the bathyscaphe and used the bathyscaphe Trieste to investigate the ocean's depths. The United States nuclear submarine Nautilus made the first journey under the ice to the North Pole in 1958. In 1962 the FLIP (Floating Instrument Platform), a 355-foot (108 m) spar buoy, was first deployed.

In 1968, Tanya Atwater led the first all-woman oceanographic expedition. Until that time, gender policies restricted women oceanographers from participating in voyages to a significant extent.

From the 1970s, there has been much emphasis on the application of large scale computers to oceanography to allow numerical predictions of ocean conditions and as a part of overall environmental change prediction. Early techniques included analog computers (such as the Ishiguro Storm Surge Computer) generally now replaced by numerical methods (e.g. SLOSH.) An oceanographic buoy array was established in the Pacific to allow prediction of El Niño events.

1990 saw the start of the World Ocean Circulation Experiment (WOCE) which continued until 2002. Geosat seafloor mapping data became available in 1995.

Study of the oceans is critical to understanding shifts in Earth's energy balance along with related global and regional changes in climate, the biosphere and biogeochemistry. The atmosphere and ocean are linked because of evaporation and precipitation as well as thermal flux (and solar insolation). Recent studies have advanced knowledge on ocean acidification, ocean heat content, ocean currents, sea level rise, the oceanic carbon cycle, the water cycle, Arctic sea ice decline, coral bleaching, marine heatwaves, extreme weather, coastal erosion and many other phenomena in regards to ongoing climate change and climate feedbacks.

In general, understanding the world ocean through further scientific study enables better stewardship and sustainable utilization of Earth's resources. The Intergovernmental Oceanographic Commission reports that 1.7% of the total national research expenditure of its members is focused on ocean science.

Additional Information

Oceanography is an interdisciplinary science where math, physics, chemistry, biology and geology intersect.

Traditionally, we discuss oceanography in terms of four separate but related branches: physical oceanography, chemical oceanography, biological oceanography and geological oceanography.

Physical oceanography involves the study of the properties (temperature, density, etc.) and movement (waves, currents, and tides) of seawater and the interaction between the ocean and the atmosphere.

Chemical oceanography involves the study of the composition of seawater and the biogeochemical cycles that affect it.

Biological oceanography involves the study of the biological organisms in the ocean (including life cycles and food production) such as bacteria, phytoplankton, zooplankton and extending to the more traditional marine biology focus of fish and marine mammals.

Geological oceanography focuses on the structure, features, and evolution of the ocean basins.

Oceanography is greater than the sum of these specific branches. Oceanographers use a variety of tools to study the ocean, and many of these studies involve more than one branch. Oceanographers collect discrete water, sediment and biological samples using ships (Research Vessels). They deploy autonomous sampling systems such as buoys and gliders to collect data over time and space scales that cannot be done with a ship. Remote sensing from aircraft and satellites allows oceanographers to get a global view of some parameters. Modeling allows oceanographers to look at the past and predict the future state of the ocean (e.g circulation, air-sea interactions, sustainability of fisheries, quality of water, etc.).

The knowledge gained from all of these types of measurements allows oceanographers to do many things including, but not limited to:

* better predict (using models) changes in weather and climate improve the forecast for hazards; natural (e.g. hurricanes) or man-made (e.g. oil spills)
* assess the impact of pollutants on the quality of water in the ocean
* protect the quality of the water in the ocean in the face of increasing human demands (e.g. fisheries, tourism, shipping, offshore oil & gas, offshore wind farms, etc.).

Jai Ganesh · Dark Discussions at Cafe Infinity

Come Quotes - IV

1. If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack. - Winston Churchill

2. There will be no end to the troubles of states, or of humanity itself, till philosophers become kings in this world, or till those we now call kings and rulers really and truly become philosophers, and political power and philosophy thus come into the same hands. - Plato

3. With mirth and laughter let old wrinkles come. - William Shakespeare

4. Come Fairies, take me out of this dull world, for I would ride with you upon the wind and dance upon the mountains like a flame! - William Butler Yeats

5. The automobile engine will come, and then I will consider my life's work complete. - Rudolf Diesel

6. It is very important to generate a good attitude, a good heart, as much as possible. From this, happiness in both the short term and the long term for both yourself and others will come. - Dalai Lama

7. Let us endeavor so to live so that when we come to die even the undertaker will be sorry. - Mark Twain

8. Nothing brings me more happiness than trying to help the most vulnerable people in society. It is a goal and an essential part of my life - a kind of destiny. Whoever is in distress can call on me. I will come running wherever they are. - Princess Diana.

Jai Ganesh · Jokes

Q: What did the green grape say to the purple grape?
A: Breathe! Breathe!
* * *
Q: Why aren't grapes ever lonely?
A: Because they come in bunches!
* * *
Q: What is purple and long?
A: The grape wall of China.
* * *
Q: What did the grape say when he got stepped on?
A: He let out a little wine.
* * *
Q: "What's purple and huge and swims in the ocean?"
A: "Moby Grape."
* * *

Jai Ganesh · Science HQ

Oscillator

Gist

An oscillator is an electronic circuit that converts DC (Direct Current) into a periodic, repeating AC (Alternating Current) signal—such as a sine, square, or triangle wave—without needing an external input signal. These devices are essential for generating, timing, and controlling frequencies in systems like radio, clocks, computers, and sensors.

Oscillators are fundamental in electronics, generating precise frequencies for applications like clocks in computers, carrier waves in radios & Wi-Fi, and timing signals in microcontrollers, enabling everything from timekeeping (watches) to data synchronization (Bluetooth) and medical devices (ultrasound), acting as versatile signal generators for diverse needs.

Summary

An electronic oscillator is an electronic circuit that produces a periodic, oscillating or alternating current (AC) signal, usually a sine wave, square wave or a triangle wave, powered by a direct current (DC) source. Oscillators are found in many electronic devices, such as radio receivers, television sets, radio and television broadcast transmitters, computers, computer peripherals, cellphones, radar, and many other devices.

Oscillators are often characterized by the frequency of their output signal:

* A low-frequency oscillator (LFO) is an oscillator that generates a frequency below approximately 20 Hz. This term is typically used in the field of audio synthesizers, to distinguish it from an audio frequency oscillator.
* An audio oscillator produces frequencies in the audio range, 20 Hz to 20 kHz.
* A radio frequency (RF) oscillator produces signals above the audio range, more generally in the range of 100 kHz to 100 GHz.

There are two general types of electronic oscillators: the linear or harmonic oscillator, and the nonlinear or relaxation oscillator. The two types are fundamentally different in how oscillation is produced, as well as in the characteristic type of output signal that is generated.

The most-common linear oscillator in use is the crystal oscillator, in which the output frequency is controlled by a piezo-electric resonator consisting of a vibrating quartz crystal. Crystal oscillators are ubiquitous in modern electronics, being the source for the clock signal in computers and digital watches, as well as a source for the signals generated in radio transmitters and receivers. As a crystal oscillator's “native” output waveform is sinusoidal, a signal-conditioning circuit may be used to convert the output to other waveform types, such as the square wave typically utilized in computer clock circuits.

Details

Oscillators are essential components in the world of electronics, playing a crucial role in generating periodic signals. From the simplest applications to complex systems, oscillators provide the timing signals needed for synchronization and control. This article explains what oscillators are and how they work, explores the various types and their performance characteristics, highlights their applications across industries, and reviews recent advancements in this essential technology.

What is an Oscillator?

An oscillator is an electronic circuit that produces a continuous, periodic signal - typically in the form of a sine wave, square wave, or triangle wave - without requiring an input signal. These signals are defined by their frequency and amplitude, which can be precisely controlled to suit specific applications. In essence, an oscillator converts energy from a DC power supply into an AC signal.

Oscillators are found in a wide array of devices, including clocks, radios, and computers. They are considered the heartbeat of electronic systems, serving as timing references that enable circuits to synchronize and function properly.

What is an Oscillator in a CPU?

A CPU oscillator is responsible for generating clock signals that regulate the timing and speed of the processor. These clock signals synchronize various CPU components, allowing for the coordinated execution of instructions.

Typically, a crystal oscillator is used, which relies on the mechanical resonance of a vibrating quartz crystal to produce a stable frequency. This precise timing is critical to a CPU’s performance and efficiency, as it directly affects the instruction execution rate.

How Do Oscillators Work?

Oscillators generate a continuous, periodic signal - such as a sine wave or square wave - without requiring an input signal of the same frequency. They achieve this through the combined principles of feedback and resonance.

Basic Components

• Amplifier: Boosts the signal.

• Feedback Network: Determines the frequency of oscillation.

• Energy Source: Supplies power to sustain the oscillation.

The system continuously feeds part of its output back to the input, allowing the signal to regenerate itself. The frequency of oscillation depends on the configuration of components such as resistors, capacitors, and inductors within the feedback loop.

Purpose of an Oscillator

The primary purpose of an oscillator is to generate consistent clock signals that control the timing and synchronization of electronic systems, especially CPUs. These signals are essential for ensuring the coordinated execution of instructions, which in turn impacts overall system performance.

Types of Oscillators:

What is an oscillator? And what are the types of oscillators?

Oscillators, essential components in electronic circuits, can be categorized based on the type of waveform they produce and their method of operation. These components are generally divided into two main categories.

Relaxation vs Linear Oscillators

Relaxation Oscillators: Produce non-sinusoidal waveforms such as sawtooth or square waves.

Linear Oscillators: Generate sinusoidal waveforms.

Specific Types

Crystal Oscillators: Crystal oscillators are linear oscillators, and use quartz crystals to generate precise frequencies. Known for their stability and accuracy, they are ideal for communication devices and clocks.

RC Oscillators: RC oscillators can be both relaxation oscillators and linear oscillators. These oscillators utilize resistors and capacitors to generate sine or square waves. Often used in audio applications due to their simplicity and cost-effectiveness.

LC Oscillators: LC oscillators are considered linear oscillators and use inductors (L) and capacitors (C) to produce oscillations. Typically employed in radio frequency (RF) applications due to their high-frequency capability.

Phase-Locked Loop (PLL) Oscillators: PLL oscillators are primarily considered linear oscillators and are used for frequency synthesis and modulation. Essential in telecommunications for signal processing and frequency control.

Emerging Oscillator Technologies

Recent advancements in oscillator technology focus on performance improvement, miniaturization, and integration with other electronic components.

MEMS Oscillators: Microelectromechanical systems offer smaller form factors, highly stable reference frequencies, and low power consumption - ideal for portable devices.

Programmable Oscillators: Allow for customized frequency outputs, reducing component count and streamlining the design process.

Devices That Use Oscillators

Many electronic devices rely on oscillators for essential functions like timing, signal generation, and frequency control. Their ability to produce consistent waveforms makes them indispensable in both consumer electronics and industrial systems.

Examples:

Quartz Watches: Use crystal oscillators to generate highly accurate timekeeping signals, ensuring the watch maintains precise seconds, minutes, and hours.

Radios: Rely on oscillators to generate carrier frequencies and to tune into specific broadcast channels for both AM and FM signals.

Computers: Employ oscillators in their system clocks to synchronize processor operations, manage data transfer, and maintain stable performance.

Cellphones: Utilize oscillators for network synchronization, frequency hopping in wireless communication, and internal clocking for processors and sensors.

Radar Systems: Depend on high-frequency oscillators to generate the radio waves that detect and measure the speed, range, and position of objects.

Metal Detectors: Use oscillators to produce electromagnetic fields that interact with metallic objects, enabling detection through changes in oscillation frequency or amplitude.

Performance Characteristics of Oscillators

Oscillators are evaluated based on several performance metrics that directly influence their suitability for specific applications. The three most critical are frequency stability, phase noise, and waveform shape.

Frequency Stability

Frequency stability describes an oscillator’s ability to maintain its output frequency under varying conditions over time.

• Short-Term Stability: Covers rapid variations over seconds or minutes, often caused by noise or small environmental changes.
• Long-Term Stability: Considers changes over hours, days, or years, typically influenced by component aging and gradual environmental shifts.
• Environmental Factors: Temperature fluctuations, supply voltage changes, and mechanical vibrations can affect stability.
• Crystal Oscillators: These oscillators excel in this area because the resonant frequency of a quartz crystal is highly resistant to such disturbances, making them ideal for precision timing applications like GPS, telecommunications, and laboratory measurement systems.

Phase Noise

Phase noise measures short-term, rapid fluctuations in the oscillator's phase, which manifest as small, random deviations from the ideal frequency.

• It is usually represented as a power density (dBc/Hz) at a given frequency offset from the carrier signal.
• Low Phase Noise: Essential in high-performance systems, such as satellite communications, radar, and high-speed data links, where timing jitter can degrade system performance or cause data errors.
• High Phase Noise: Can lead to signal distortion, reduced sensitivity in receivers, and degraded performance in frequency synthesizers.

Waveform Shape

The oscillator’s output waveform determines how well it interfaces with downstream circuitry.

• Sine Waves: Preferred in RF applications because they have minimal harmonic content, reducing the need for filtering.
• Square Waves: Common in digital clocking applications, as their fast transitions make it easy for digital circuits to detect logic states.
• Sawtooth or Triangular Waveforms: May be required in specialized systems, such as sweep generators in analog oscilloscopes.
• Poor Waveform Shape: Can cause signal integrity issues, increased electromagnetic interference (EMI), or inaccurate timing in digital circuits.

Are Oscillators Active Components?

Oscillators are classified as active components. They amplify electrical signals and generate power, distinguishing them from passive components like resistors and capacitors. While oscillators incorporate passive elements in their circuits, their role in signal generation qualifies them as active devices.

Industries That Use Oscillators

Oscillators' ability to generate stable, precise signals makes them indispensable for timing, synchronization, and frequency control across a wide range of sectors. The specific oscillator type used often depends on the application's demands - whether it’s ultra-high precision, rugged durability, or low power consumption.

Telecommunications: Oscillators generate carrier signals for data transmission. Their stability and accuracy ensure signal integrity over long distances. Crystal and PLL oscillators are widely used here.

Consumer Electronics: Devices like smartphones and TVs rely on oscillators to generate clock signals for microcontrollers. Their precision directly impacts device performance.

Automotive: Used in engine control units, infotainment systems, and sensor applications (e.g., ABS), oscillators regulate timing for ignition and fuel injection.

Medical Devices: Essential in pacemakers and diagnostic tools, where reliability and precision are critical. Crystal oscillators are often chosen for their long-term stability.

Additional Information

An oscillator is an electronic device that produces repetitive oscillating signals in the form of a sine wave, a square wave, or a triangle wave. Basically, this circuit converts DC (Direct Current) into an AC (Alternating Current) signal at a specific frequency.

An oscillator is essential in various electronic devices. It is used in Bluetooth modules for frequency generation and maintaining a stable connection. In relays, oscillators help with debouncing and pulse generation.

In sensors, they are used for generating carrier signals and stabilizing readings. Integrated circuits (ICs) use oscillators for clock generation and data synchronization. In connectors, oscillators assist with signal integrity and timing matching.

Microcontrollers rely on oscillators for peripheral operation and system clock management. Additionally, oscillators are used in LCD and LED displays for backlight control and data driving.

A basic oscillator circuit typically includes components like an amplifier stage, a feedback network, frequency-determining components, and a power supply.

1. Amplifier

An amplifier in an oscillator can be a transistor, an operational amplifier, or any active device that boosts small signals to maintain continuous oscillations. For that amplifier must provide a gain greater than or equal to one to sustain oscillations.

2. Feedback Network

In this network, it feeds a portion of the output back to the input with the correct phase. This network includes components like capacitive, inductive, or resistive networks like LC circuits or RC circuits.

3. Frequency Determining Components

This component sets the frequency at which the oscillator operates, which includes RC networks, LC networks, and crystal resonators.

4. Power Supply

It provides the necessary voltage and current for operation.

Types of Oscillators

Based on the design, frequency range, and application, oscillators are classified into various types. They are as follows:

1. LC Oscillator

An LC oscillator uses an inductor and a capacitor to determine the frequency of oscillation. It is a high-frequency operation oscillator that gives a smooth sine wave output, and its frequency depends on the values of L and C.

LC oscillator consists of different types like Hartley Oscillator (uses a tapped inductor), Colpitts Oscillator (uses a capacitive voltage divider), and Clapp Oscillator ( it is a variation of the Colpitts with an additional capacitor for better frequency stability.

It is mostly used in radio transmitters, RF communication circuits, and signal generators.

2. RC Oscillator

RC oscillator uses resistors and capacitors to produce oscillations. It produces stable low-frequency sine waves and is ideal for audio frequency generation, which is cost cost-effective design.

This includes the Wien bridge oscillator (for audio applications) and the Phase shift oscillator (produces sine waves using multiple RC stages). RC oscillators are used in audio signal generation, function generation, and low-frequency timing circuits.

3. Crystal Oscillator

To create a very stable frequency oscillation, a crystal oscillator uses the mechanical resonance of a quartz crystal. It generates a pure sine wave output with extremely high frequency stability. They have very low frequency drift due to temperature changes.

These are of the types Pierce oscillator and AT-cut crystal oscillator (widely used in microcontrollers). It is used in microcontrollers and microprocessors, Bluetooth and Wi-Fi modules, digital watches and clocks, and GPS systems.

Working Principle of Oscillator

The working principle of an oscillator is based on the concept of positive feedback and energy conversion from a direct current (DC) source into an alternating current (AC) signal at a specific, stable frequency.

The working of the oscillator is explained in step below:

1. Initial

Due to thermal activity, every electronic circuit has inherent noise, and this tiny noise signal acts as the seed for oscillation.

2. Amplification

At the amplification stage, the amplifier boosts this initial noise signal, and amplification must be sufficient to compensate for any losses in the feedback network.

3. Positive Feedback Loop

A portion of the output is fed back to the input in phase, which reinforces the input signal rather than cancelling it.

4. Frequency Selection

The frequency-determining network (RC, LC, or crystal) controls the frequency of oscillation.

5. Steady State Oscillation

As the feedback sustains the oscillations, the amplitude stabilizes. Non-linear effects or amplitude limiting mechanisms prevent the output from growing indefinitely, ensuring stable oscillations.

Applications of Oscillators

1. Communication Systems

* Oscillators generate high-frequency carrier signals for AM, FM, and digital modulation.
* Used to produce a range of frequencies from a single oscillator source.
* LC and crystal oscillators are used for tuning and frequency control.

Example: Radio Transmitters, Mobile phones, Wi-Fi modules, Bluetooth devices

2. Microcontrollers and Microprocessors

* Oscillators provide the clock signals needed for the timing and operation of microcontrollers and microprocessors.
* Crystal oscillators generate precise timing signals that ensure all processes operate in harmony and within correct timing constraints.

Example: Arduino boards, PIC microcontrollers, Embedded systems.

3. Sensors

* Oscillators are used in sensor circuits for data acquisition and signal processing.

Example: Proximity sensors, Ultrasonic sensors, and Environmental monitoring systems.

4. Display Technologies

Oscillators help maintain the refresh rate of digital displays. Used in the PWM (Pulse Width Modulation) circuits for adjusting display brightness.

Example: LED displays, LCD displays, OLED panels, Digital signage.

Frequently Asked Questions:

1. Is an Oscillator AC or DC?

An oscillator converts DC power into an AC signal by generating a continuous, oscillating waveform without an external input.

2. Is the Oscillator Negative or Positive?

An oscillator uses positive feedback to sustain continuous oscillations.

3. Which Oscillator is Better?

The crystal oscillator is considered better for applications requiring high-frequency stability and accuracy.

4. How Does an Oscillator Differ from an Amplifier?

An oscillator generates its own periodic signal without an external input, while an amplifier boosts the strength of an existing input signal.

5. What is the Difference Between RC and LC Oscillators?

An RC oscillator uses resistors and capacitors for low-frequency generation, while an LC oscillator uses inductors and capacitors for high-frequency generation.

6. What Causes an Oscillator to Fail?

An oscillator can fail due to component aging, temperature variations, power supply issues, or physical damage to the resonator elements, like crystals or inductors.

7. Can an Oscillator be Used as a Signal Generator?

Yes, an oscillator can be used as a signal generator to produce continuous waveforms like sine, square, or triangular signals.

What%20is%20an%20Oscillator%20Types-%20Circuit-%20Working-%20and%20Applications.jpg

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2709.

Jai Ganesh · Dark Discussions at Cafe Infinity

2433) Yang Chen-Ning

Gist:

Work

For a long time, physicists assumed that various symmetries characterized nature. In a kind of “mirror world” where right and left were reversed and matter was replaced by antimatter, the same physical laws would apply, they posited. The equality of these laws was questioned concerning the decay of certain elementary particles, however, and in 1956 Chen Ning Yang and Tsung Dao Lee formulated a theory that the left-right symmetry law is violated by the weak interaction. Measurements of electrons’ direction of motion during a cobalt isotope’s beta decay confirmed this.

Summary

Chen Ning Yang (born October 1, 1922, Hofei, Anhwei, China—died October 18, 2025, Beijing, China) was a Chinese-born American theoretical physicist whose research with Tsung-Dao Lee showed that parity—the symmetry between physical phenomena occurring in right-handed and left-handed coordinate systems—is violated when certain elementary particles decay. Until this discovery it had been assumed by physicists that parity symmetry was as universal a law as the conservation of energy or electric charge. This and other studies in particle physics earned Yang and Lee the Nobel Prize for Physics for 1957.

Life

Yang’s father, Yang Ko-chuen (also known as Yang Wu-chih), was a professor of mathematics at Tsinghua University, near Peking. While still young, Yang read the autobiography of Benjamin Franklin and adopted “Franklin” as his first name. After graduation from the Southwest Associated University, in K’unming, he took his B.Sc. in 1942 and his M.S. in 1944. On a fellowship, he studied in the United States, enrolling at the University of Chicago in 1946. He took his Ph.D. in nuclear physics with Edward Teller and then remained in Chicago for a year as an assistant to Enrico Fermi, the physicist who was probably the most influential in Yang’s scientific development. Lee had also come to Chicago on a fellowship, and the two men began the collaboration that led eventually to their Nobel Prize work on parity. In 1949 Yang went to the Institute for Advanced Study in Princeton, New Jersey, and became a professor there in 1955. He became a U.S. citizen in 1964.

Work

Almost from his earliest days as a physicist, Yang had made significant contributions to the theory of the weak interactions—the forces long thought to cause elementary particles to disintegrate. (The strong forces that hold nuclei together and the electromagnetic forces that are responsible for chemical reactions are parity-conserving. Since these are the dominant forces in most physical processes, parity conservation appeared to be a valid physical law, and few physicists before 1955 questioned it.) By 1953 it was recognized that there was a fundamental paradox in this field since one of the newly discovered mesons—the so-called K meson—seemed to exhibit decay modes into configurations of differing parity. Since it was believed that parity had to be conserved, this led to a severe paradox.

After exploring every conceivable alternative, Lee and Yang were forced to examine the experimental foundations of parity conservation itself. They discovered, in early 1956, that, contrary to what had been assumed, there was no experimental evidence against parity nonconservation in the weak interactions. The experiments that had been done, it turned out, simply had no bearing on the question. They suggested a set of experiments that would settle the matter, and, when these were carried out by several groups over the next year, large parity-violating effects were discovered. In addition, the experiments also showed that the symmetry between particle and antiparticle, known as charge conjugation symmetry, is also broken by the weak decays.

In addition to his work on weak interactions, Yang, in collaboration with Lee and others, carried out important work in statistical mechanics—the study of systems with large numbers of particles—and later investigated the nature of elementary particle reactions at extremely high energies. From 1965 Yang was Albert Einstein professor at the Institute of Science, State University of New York at Stony Brook, Long Island. During the 1970s he was a member of the board of Rockefeller University and the American Association for the Advancement of Science and, from 1978, of the Salk Institute for Biological Studies, San Diego. He was also on the board of Ben-Gurion University, Beersheba, Israel. He received the Einstein Award in 1957 and the Rumford Prize in 1980; in 1986 he received the Liberty Award and the National Medal of Science.

Details

Yang Chen-Ning (1 October 1922 – 18 October 2025) also known as C.N. Yang and Franklin Yang, was a Chinese-American theoretical physicist who made significant contributions to statistical mechanics, integrable systems, gauge theory, particle physics and condensed matter physics.

Yang is known for his collaboration with Robert Mills in 1954 in developing non-abelian gauge theory, widely known as the Yang–Mills theory, which describes the nuclear forces in the Standard Model of particle physics.

Yang and Tsung-Dao Lee received the 1957 Nobel Prize in Physics for their work on parity non-conservation of the weak interaction, which was confirmed by the Wu experiment in 1956. The two proposed that the conservation of parity, a physical law observed to hold in all other physical processes, is violated in weak nuclear reactions – those nuclear processes that result in the emission of beta or alpha particles.

Early life and education

Yang was born in Hefei, Anhui, China, on 1 October 1922. His mother was Luo Meng-hua and his father, Ko-Chuen Yang (1896–1973), was a mathematician.

Yang attended elementary school and high school in Beijing, and in the autumn of 1937 his family moved to Hefei after the Japanese invaded China. In 1938 they moved to Kunming, Yunnan, where National Southwestern Associated University was located. In the same year, as a second-year student, Yang passed the entrance examination and studied at National Southwestern Associated University. He received a Bachelor of Science in 1942, with his thesis on the application of group theory to molecular spectra, under the supervision of Ta-You Wu.

Yang continued to study graduate courses there for two years under the supervision of Wang Zhuxi (J.S. Wang), working on statistical mechanics. In 1944, he received a Master of Science from National Tsing Hua University, which had moved to Kunming during the Sino-Japanese War (1937–1945). Yang was then awarded a scholarship from the Boxer Indemnity Scholarship Program, set up by the United States government using part of the money China had been forced to pay following the Boxer Rebellion. His departure for the United States was delayed for one year, during which time he taught in a middle school as a teacher and studied field theory.

Yang entered the University of Chicago in January 1946 and studied with Edward Teller. He received a Doctor of Philosophy in 1948.

Career

Yang remained at the University of Chicago for a year as an assistant to Enrico Fermi. In 1949 he was invited to do his research at the Institute for Advanced Study in Princeton, New Jersey, where he began a period of fruitful collaboration with Tsung-Dao Lee. Lee and Yang published 32 papers together. He was made a permanent member of the Institute in 1952, and full professor in 1955. In 1963, Princeton University Press published his textbook, Elementary Particles. In 1965 he moved to Stony Brook University, where he was named the Albert Einstein Professor of Physics and the first director of the newly founded Institute for Theoretical Physics. Today this institute is known as the C. N. Yang Institute for Theoretical Physics. Yang retired from Stony Brook University in 1999.

Yang visited the Chinese mainland in 1971 for the first time after the thaw in China–US relations, and subsequently worked to help the Chinese physics community rebuild the research atmosphere, which later eroded due to political movements during the Cultural Revolution. After retiring from Stony Brook, he returned to Beijing as an honorary director of Tsinghua University, where he was the first Huang Jibei-Lu Kaiqun Professor at the Center for Advanced Study (CASTU). He was also one of the two Shaw Prize Founding Members and was a Distinguished Professor-at-Large at the Chinese University of Hong Kong.

Yang helped to establish the Theoretical Physics Division at the Chern Institute of Mathematics in 1986 at the request of Shiing-Shen Chern who was serving as the inaugural director of the Institute at the time.

Personal life and death

Yang married Tu Chih-li, a teacher, in 1950; they had two sons and a daughter together. His father-in-law was the Kuomintang general Du Yuming. Tu died in October 2003. In January 2005, Yang married Weng Fan, a university student. They met in 1995 at a physics seminar; the couple reestablished contact in February 2004 when Yang moved to China to become affiliated with Tsinghua University. Yang called Weng, who was 54 years his junior, his "final blessing from God".

Yang obtained U.S. citizenship during his research within the country. According to the state-run Xinhua News Agency, Yang said the decision was painful as his father never forgave him for that. According to Xinhua and other mainstream Chinese media, he formally renounced his American citizenship on April 1, 2015. He acknowledged that while the U.S. was a beautiful country that gave him good opportunities to study science, China since his youth had offered the best secondary and undergraduate institutions, though the US had the top graduate studies. However, circumstances changed in favor of China's growth by the turn of the century.

His son Guangnuo was a computer scientist. His second son Guangyu is an astronomer, and his daughter Youli is a doctor.

Yang turned 100 on 1 October 2022, and died in Beijing on 18 October 2025, at the age of 103. The day after the announcement of his death, people gathered and waited in line at Tsinghua University to pay tributes to Yang.

Views on the CEPC

Yang is known for having opposed the construction of the Circular Electron Positron Collider (CEPC), a 100 km circumference particle collider in China that would study the Higgs boson. He catalogued the project as "guess" work and without guaranteed results. Yang said that "even if they see something with the machine, it's not going to benefit the life of Chinese people any sooner."

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