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#1 Re: Jai Ganesh's Puzzles » General Quiz » Yesterday 22:47:56

Hi,

#9803. What does the term in Geography Water-meadow mean?

#9804. What does the term in Geography Washland mean?

#2 Dark Discussions at Cafe Infinity » Chances Quotes - IV » Yesterday 22:02:01

Jai Ganesh
Replies: 0

Chances Quotes - IV

1. I'm not a part of the glamour industry. I would like to focus on my game, and there are minimal chances of me getting into films. - Sania Mirza

2. Tennis is like, it gives you a lot of chances, but if you don't take those chances, it takes a lot of chances away from you. It's just the scoring pattern. We cannot dwell over a loss or a win for very long. We have no time to celebrate; we have no time to dwell; we have to move on. Wake up the next day and try and win the match. - Sania Mirza

3. I think men are more adventurous in that they're more likely to take chances. Women play it safe. But now, maybe more of the women that see how it's working for the guys think, 'I can do that, too'. Maybe they'll pick male players, not necessarily female players; it's just whatever that match is that works for that player. - Martina Navratilova

4. My chances of developing breast cancer have dropped from 87 percent to under 5 percent. I can tell my children that they don't need to fear they will lose me to breast cancer. - Angelina Jolie

5. T20 is an unpredictable format, so you cannot rule out any team's chances. - Inzamam-ul-Haq

6. When you are performing at the top level you don't get many chances to go back to basics as you are in elite performance mode. It's hard to break your technique or action down when it always needs to be at a match intensity. -Stuart Broad.

second-chances-blog.jpg

#3 Science HQ » Lead » Yesterday 18:17:33

Jai Ganesh
Replies: 0

Lead

Gist

Lead is a chemical element; it has symbol Pb (from Latin plumbum) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, lead is a shiny gray with a hint of blue.

Details

Lead is a chemical element; it has symbol Pb (from Latin plumbum) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, lead is a shiny gray with a hint of blue. It tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements.

Lead is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are mostly limited to organolead compounds. Like the lighter members of the group, lead tends to bond with itself; it can form chains and polyhedral structures.

Since lead is easily extracted from its ores, prehistoric people in the Near East were aware of it. Galena is a principal ore of lead which often bears silver. Interest in silver helped initiate widespread extraction and use of lead in ancient Rome. Lead production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution. Lead played a crucial role in the development of the printing press, as movable type could be relatively easily cast from lead alloys. In 2014, the annual global production of lead was about ten million tonnes, over half of which was from recycling. Lead's high density, low melting point, ductility and relative inertness to oxidation make it useful. These properties, combined with its relative abundance and low cost, resulted in its extensive use in construction, plumbing, batteries, bullets and shot, weights, solders, pewters, fusible alloys, white paints, leaded gasoline, and radiation shielding.

Lead is a neurotoxin that accumulates in soft tissues and bones. It damages the nervous system and interferes with the function of biological enzymes, causing neurological disorders ranging from behavioral problems to brain damage, and also affects general health, cardiovascular, and renal systems. Lead's toxicity was first documented by ancient Greek and Roman writers, who noted some of the symptoms of lead poisoning, but became widely recognized in Europe in the late 19th century.

Physical properties

Atomic

A lead atom has 82 electrons. The sum of lead's first and second ionization energies—the total energy required to remove the two 6p electrons—is close to that of tin, lead's upper neighbor in the carbon group. This is unusual; ionization energies generally fall going down a group, as an element's outer electrons become more distant from the nucleus, and more shielded by smaller orbitals.

The sum of the first four ionization energies of lead exceeds that of tin, contrary to what periodic trends would predict. This is explained by relativistic effects, which become significant in heavier atoms, which contract s and p orbitals such that lead's 6s electrons have larger binding energies than its 5s electrons. A consequence is the so-called inert pair effect: the 6s electrons of lead become reluctant to participate in bonding, stabilising the +2 oxidation state and making the distance between nearest atoms in crystalline lead unusually long.

Lead's lighter carbon group congeners form stable or metastable allotropes with the tetrahedrally coordinated and covalently bonded diamond cubic structure. The energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp3 orbitals. In lead, the inert pair effect increases the separation between its s- and p-orbitals, and the gap cannot be overcome by the energy that would be released by extra bonds following hybridization. Rather than having a diamond cubic structure, lead forms metallic bonds in which only the p-electrons are delocalized and shared between the Pb2+ ions. Lead consequently has a face-centered cubic structure like the similarly sized divalent metals calcium and strontium.

Bulk

Pure lead has a bright, shiny gray appearance with a hint of blue. It tarnishes on contact with moist air and takes on a dull appearance, the hue of which depends on the prevailing conditions. Characteristic properties of lead include high density, malleability, ductility, and high resistance to corrosion due to passivation.

Lead's close-packed face-centered cubic structure and high atomic weight result in a density of 11.34 g/{cm}^3, which is greater than that of common metals such as iron (7.87 g/{cm}^3), copper (8.93 g/{cm}^3), and zinc (7.14 g/{cm}^3). This density is the origin of the idiom to go over like a lead balloon. Some rarer metals are denser: tungsten and gold are both at 19.3 g/{cm}^3, and osmium—the densest metal known—has a density of 22.59 g/{cm}^3, almost twice that of lead.

68e8cf17-977c-4b0e-b4c7-167998f98a19_lead-ingot.jpg?auto=compress%2Cformat&rect=122%2C0%2C758%2C758&w=486&h=486&fit=max&fm=webp

#4 This is Cool » Similarity (geometry) » Yesterday 17:45:46

Jai Ganesh
Replies: 1

Similarity (geometry)

In Euclidean geometry, two objects are similar if they have the same shape, or if one has the same shape as the mirror image of the other. More precisely, one can be obtained from the other by uniformly scaling (enlarging or reducing), possibly with additional translation, rotation and reflection. This means that either object can be rescaled, repositioned, and reflected, so as to coincide precisely with the other object. If two objects are similar, each is congruent to the result of a particular uniform scaling of the other.

For example, all circles are similar to each other, all squares are similar to each other, and all equilateral triangles are similar to each other. On the other hand, ellipses are not all similar to each other, rectangles are not all similar to each other, and isosceles triangles are not all similar to each other. This is because two ellipses can have different width to height ratios, two rectangles can have different length to breadth ratios, and two isosceles triangles can have different base angles.

If two angles of a triangle have measures equal to the measures of two angles of another triangle, then the triangles are similar. Corresponding sides of similar polygons are in proportion, and corresponding angles of similar polygons have the same measure.

Two congruent shapes are similar, with a scale factor of 1. However, some school textbooks specifically exclude congruent triangles from their definition of similar triangles by insisting that the sizes must be different if the triangles are to qualify as similar.

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#5 Re: Dark Discussions at Cafe Infinity » crème de la crème » Yesterday 14:43:20

1454) Yuan T. Lee

Gist

Yuan Tseh Lee (born 19 November 1936) is a Taiwanese chemist. He is a Professor Emeritus at the University of California, Berkeley. He was the first Taiwanese Nobel Prize laureate who, along with the Hungarian-Canadian John C. Polanyi and American Dudley R. Herschbach, won the Nobel Prize in Chemistry in 1986 "for their contributions to the dynamics of chemical elementary processes".

Lee's particular physical chemistry work was related to the use of advanced chemical kinetics techniques to investigate and manipulate the behavior of chemical reactions using crossed molecular beams. From 15 January 1994 to 19 October 2006, Lee served as the President of the Academia Sinica of Taiwan. In 2011, he was elected head of the International Council for Science.

Early life

Lee was born to a Hokkien family in Shinchiku City (modern-day Hsinchu city) in northern Taiwan, which was then under Japanese rule, to Lee Tze-fan, an artist, and Ts'ai P'ei C(ài Péi), an elementary school teacher from Goseikō Town , Taichū Prefecture (Wuqi, Taichung). Lee is a Hokkien with ancestry from Nan'an City, China. Lee played on the baseball and ping-pong teams of Hsinchu Elementary School, and later studied at the Hsinchu Senior High School, where he played tennis, trombone, and the flute.

He was exempted from the entrance examination and directly admitted to National Taiwan University. He earned a BSc in 1959. He earned his MS from National Tsing Hua University in 1961 and his PhD from the University of California, Berkeley in 1965 under the supervision of Bruce H. Mahan. He was a member of the Chemistry International Board from 1977 to 1984.

Scientific career

Chemistry

In February 1967, he started working with Dudley Herschbach at Harvard University on reactions between hydrogen atoms and diatomic alkali molecules and the construction of a universal crossed molecular beams apparatus. After the postdoctoral year with Herschbach he joined the University of Chicago faculty in 1968. In 1974, he returned to Berkeley as professor of chemistry and principal investigator at the Lawrence Berkeley National Laboratory, becoming a U.S. citizen the same year. Lee is a University Professor Emeritus of the University of California system.[7]

Nobel prize

One of the major goals of chemistry is the study of material transformations where chemical kinetics plays an important role. Scientists during the 19th century stated macroscopic chemical processes consist of many elementary chemical reactions that are themselves simply a series of encounters between atomic or molecular species. In order to understand the time dependence of chemical reactions, chemical kineticists have traditionally focused on sorting out all of the elementary chemical reactions involved in a macroscopic chemical process and determining their respective rates.

Swedish chemist Svante Arrhenius studied this phenomenon during the late 1880s, and stated the relations between reactive molecular encounters and rates of reactions (formulated in terms of activation energies).

Other scientists at the time also stated a chemical reaction is fundamentally a mechanical event, involving the rearrangement of atoms and molecules during a collision. Although these initial theoretical studies were only qualitative, they heralded a new era in the field of chemical kinetics; allowing the prediction of the dynamical course of a chemical reaction.

In the 1950s, 1960s and 1970s, with the development of many sophisticated experimental techniques, it became possible to study the dynamics of elementary chemical reactions in the laboratory. Such as the analysis of the threshold operating conditions of a chemical laser or the spectra obtained using various linear or non-linear laser spectroscopic techniques.

Professor Lee's research focused on the possibility to control the energies of the reagents, and to understand the dependence of chemical reactivity on molecular orientation, among other studies related to the nature of reaction intermediates, decay dynamics, and identifying complex reaction mechanisms. To do so, Professor Lee used a breakthrough laboratory technique at the time, called the "crossed molecular beams technique", where the information derived from the measurements of angular and velocity distributions allowed him and his team to understand the dynamics of elementary chemical reactions.

Recent works

During his tenure, Lee has worked to create new research institutes, advance scientific research within Taiwan, and to recruit and cultivate top scholars for the Academic Sinica.

In 2010, Lee said that global warming would be much more serious than scientists previously thought, and that Taiwanese people needed to cut their per-capita carbon emissions from the current 12 tons per year to just three. This would take more than a few slogans, turning off the lights for one hour, or cutting meat consumption, noting: "We will have to learn to live the simple lives of our ancestors." Without such efforts, he said, "Taiwanese will be unable to survive long into the future".

He has been involved with the Malta Conferences, an initiative designed to bring together Middle Eastern scientists. As part of the initiative, he offered six fellowships to work on the synchrotron in Taiwan.

He is also a member of International Advisory Council in Universiti Tunku Abdul Rahman.

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#6 Jokes » Squirrel Jokes - I » Yesterday 14:11:24

Jai Ganesh
Replies: 0

Q: Why do squirrels swim on there back?
A: To keep their nuts dry!
* * *
Q: Why can't you be friends with a squirrel?
A: They drive everyone nuts.
* * *
Q: What is a squirrels favorite ballet?
A; The nutcracker.
* * *
Q: Why did the squirrel take apart the classic car?
A: To get down to the nuts and bolts.
* * *
Q: Why couldn't the squirrel eat the macadamia nut?
A: It was one tough nut to crack.
* * *

#9 Re: This is Cool » Miscellany » Yesterday 00:12:59

2157) Grape Juice

Details

Grape juice is a beverage known for its vibrant color and sweet, slightly tart flavor.

Many people consider it a healthy alternative to sugary beverages, like soda. In fact, according to the most recent Dietary Guidelines for Americans, 100% fruit juice can be enjoyed as part of a balanced diet.

However, due to its content of sugar and calories, you may wonder if grape juice is as healthy as fresh fruit.

This article explores the nutritional content, benefits, and downsides of grape juice, so you can learn if it’s good for you.

Types of grape juice

There are several types of grape juice. They differ in nutritional content and which specific grapes they’re made from.

Purple grape juice is the most commonly available commercial variety. It features a dark color and is usually made from Concord grapes.

You can also purchase white grape juice, which is made from green-skinned grapes and boasts a slightly sweeter taste.

Some grape juice is labeled as 100% juice, meaning that all the ingredients are extracted from fruits or vegetables.

Other varieties are labeled as juice from concentrate. That means that most of the water has been removed, resulting in a more concentrated product.

Grape juice is also featured in many juice math, some of which contain a blend of several types of fruit.

Grape juice may be sweetened or unsweetened. Sweetened grape juice contains added sugars, like high fructose corn syrup. Added sugar can be found listed on the ingredients label.

SUMMARY

There are several types of grape juice available. They differ depending on whether they’re sweetened, the types of grapes used, and whether they’re made from concentrate, a blend of fruits, or 100% fruit juice.

Nutrients

Though grape juice is high in carbs and natural sugar, it’s also a good source of several nutrients, including vitamin C and manganese.

One cup (237 mL) of unsweetened purple grape juice contains the following nutrients:

Calories: 152
Protein: 1 gram
Fat: 0.3 grams
Carbs: 37.4 grams
Fiber: 0.5 grams
Vitamin C: 70% of the Daily Value (DV)
Manganese: 26% of the DV
Magnesium: 6% of the DV
Potassium: 6% of the DV
Copper: 5% of the DV

Many types of grape juice contain added ascorbic acid, also known as vitamin C. This nutrient is essential for immune function and skin health.

Grape juice is also rich in manganese, a mineral involved in bone formation and the production of certain neurotransmitters in your brain.

What’s more, grape juice contains several flavonoids and polyphenols. These are plant compounds that act as antioxidants to protect against oxidative stress and inflammation.

SUMMARY

Grape juice is high in carbs, but it also contains a good amount of vitamin C, manganese, and antioxidants in each serving.

Benefits

Grape juice has been associated with several health benefits. For example, it may promote the health of your heart, immune system, and digestive tract.

Enhances heart health

Thanks to its content of antioxidant compounds, several studies have found that grape juice could support heart health.

According to one review, the flavonoids found in Concord grape juice could help lower several risk factors for heart disease, including:

* inflammation
* plaque build-up in the arteries
* platelet aggregation
* cholesterol and triglyceride levels

In a small study with 25 women, drinking white grape juice daily for 30 days increased levels of HDL (good) cholesterol by 16% and decreased belly fat.

Similarly, a review reported that grape products, including grape juice, could significantly improve levels of total, LDL (bad), and HDL (good) cholesterol compared with a control. As such, it might help protect against heart disease.

Still, more high quality research is needed to better understand the juice’s effects on heart health.

Promotes immune function

Many varieties of grape juice are enriched with the micronutrient vitamin C.

Vitamin C can enhance immune function by reducing oxidative stress and supporting the function of your immune cells.

Getting enough vitamin C in your daily diet may reduce your susceptibility to illness and infection, including respiratory infections, like the common cold.

Grape juice is also a great source of antioxidants, like resveratrol, a compound that can reduce inflammation and regulate immune cells.

Supports digestive health

Some research has found that grape juice might support the health of your digestive system.

For instance, a recent study showed that taking a grape powder supplement — equivalent to about 3.4 ounces (100 mL) of grape juice — could increase the diversity of your beneficial gut microbiome to promote digestive health.

Several studies in animals have found similar results, noting that certain compounds and polyphenols extracted from grapes and grape juice could support the health of the gut microbiome.

Some types of grape juice also contain a small amount of fiber, with around 0.5 grams per cup (237 mL).

Although this is much less than the amount found in whole grapes, it can help you meet your daily needs for fiber, an essential nutrient that promotes regularity and digestive health.

SUMMARY

Some studies show that grape juice and its components could improve heart health, promote immune function, and support digestive health.

Downsides

Though grape juice can be enjoyed in moderation as part of a healthy diet, there are a few downsides to consider.

May increase blood sugar levels

Grape juice contains a high amount of natural sugars. Even unsweetened varieties pack 36 grams into each 1-cup (237-mL) serving.

Compared with whole fruits, fruit juice is also lower in fiber. Fiber slows the absorption of sugar into the bloodstream to stabilize blood sugar levels.

Several types are also sweetened with high amounts of added sugar. Studies show that increased intake of sugar-sweetened beverages may be linked to a higher risk of type 2 diabetes and impaired blood sugar control.

That said, unsweetened varieties may not have the same effects. Some studies show that drinking 100% fruit juice isn’t associated with higher blood sugar levels or an increased risk of type 2 diabetes.

Could contribute to weight gain

Grape juice is low in fiber, meaning that it doesn’t increase feelings of fullness to the same extent as whole fruits.

Studies show that liquids are less filling than solid foods. So, you might feel more hungry after drinking a glass of grape juice compared with eating fresh grapes.

Sugar-sweetened beverages, such as grape juice with added sugar, have also been linked to a higher risk of weight gain, overweight, and obesity among children and adults.

Additionally, some types of sweetened grape juice are high in calories and can contribute to weight gain if consumed in high amounts and if you don’t make other adjustments to your diet.

SUMMARY

Grape juice is low in fiber and some types contain added sugar, which could negatively impact blood sugar control. Certain varieties may also contribute to weight gain, especially if you don’t make other adjustments to your diet.

Should you drink grape juice?

Grape juice is a good source of several important vitamins, minerals, and antioxidants and can fit into a healthy, well-rounded diet.

Be sure to keep your intake moderate. While the Dietary Guidelines for Americans recommends limiting your intake to 4–10 ounces (118–296 mL) per day, other research shows that drinking 3.4–5 ounces (100–150 mL) per day may offer the most health benefits.

Ideally, choose unsweetened varieties made with 100% grape juice and steer clear of brands that contain added sugar like high fructose corn syrup.

Alternatively, opt for whole grapes instead. These contain the same beneficial nutrients as grape juice, along with a higher amount of fiber to support healthy blood sugar levels.

SUMMARY

Grape juice can be enjoyed in moderation as part of a balanced diet. Stick to unsweetened varieties made with 100% grape juice or opt for whole, fiber-rich grapes instead.

The bottom line

Grape juice is a good source of several important nutrients, including vitamin C, manganese, and antioxidants.

It’s also linked to several health benefits. For example, it may support heart health, immune function, and digestive health.

However, it’s also high in sugar and has less fiber than whole fruits. It could increase blood sugar levels or contribute to weight gain if consumed in large amounts.

Therefore, it’s best to stick to a moderate intake and select unsweetened varieties made with 100% grape juice whenever possible.

Alternatively, choose whole fruits instead to increase your fiber intake and take advantage of the many health benefits that grapes have to offer.

Additional Information

Grape juice is obtained from crushing and blending grapes into a liquid. In the wine industry, grape juice that contains 7–23 percent of pulp, skins, stems and seeds is often referred to as must. The sugars in grape juice allow it to be used as a sweetener, and fermented and made into wine, brandy, or vinegar.

In North America, the most common grape juice is purple and made from Concord grapes while white grape juice is commonly made from Niagara grapes, both of which are varieties of native American grapes, a different species from European wine grapes. In California, Sultana (known there as 'Thompson Seedless') grapes are sometimes diverted from the raisin or table market to produce white juice.

Grape juice can be made from all grape varieties after reaching appropriate maturity. Because of consumers' preferences for characteristics in colour, flavour and aroma, grape juice is primarily produced from American cultivars of Vitis labrusca.

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#10 This is Cool » Cousin Prime » 2024-05-18 22:59:50

Jai Ganesh
Replies: 0

Cousin Prime

In number theory, cousin primes are prime numbers that differ by four. Compare this with twin primes, pairs of prime numbers that differ by two, and sexy primes, pairs of prime numbers that differ by six.

The cousin primes below 1000 are:

(3, 7), (7, 11), (13, 17), (19, 23), (37, 41), (43, 47), (67, 71), (79, 83), (97, 101), (103, 107), (109, 113), (127, 131), (163, 167), (193, 197), (223, 227), (229, 233), (277, 281), (307, 311), (313, 317), (349, 353), (379, 383), (397, 401), (439, 443), (457, 461), (463,467), (487, 491), (499, 503), (613, 617), (643, 647), (673, 677), (739, 743), (757, 761), (769, 773), (823, 827), (853, 857), (859, 863), (877, 881), (883, 887), (907, 911), (937, 941), (967, 971).

Properties

The only prime belonging to two pairs of cousin primes is 7. One of the numbers n, n + 4, n + 8 will always be divisible by 3, so n = 3 is the only case where all three are primes.

#11 Re: Dark Discussions at Cafe Infinity » crème de la crème » 2024-05-18 22:03:43

1453) Herbert A. Hauptman

Gist

When mapping the molecular structure of molecules, it is important to study how X-rays, electromagnetic waves with a short wavelength, are bent by a crystal. What is important is the ray’s direction, intensity and phase—how the wave crests are displaced. During the first part of the 1950s, Herbert Hauptman and Jerome Karle developed a system of equations that used measurements of the rays’ intensity to determine their phases. This made direct determination of molecular structures possible.

Summary

Herbert A. Hauptman (born February 14, 1917, New York, New York, U.S.—died October 23, 2011, Buffalo, New York) was an American mathematician and crystallographer who, along with Jerome Karle, received the Nobel Prize for Chemistry in 1985. They developed mathematical methods for deducing the molecular structure of chemical compounds from the patterns formed when X-rays are diffracted by their crystals.

Hauptman was a classmate with Karle at City College of New York, from which they both graduated in 1937. Hauptman went on to study mathematics further at Columbia University (M.A., 1939) and at the University of Maryland (Ph.D., 1955). After World War II Hauptman was reunited with Karle at the Naval Research Laboratory (Washington, D.C.), where they began collaborating on the study of crystal structures. In 1970 Hauptman became a professor of biophysics at the State University of New York at Buffalo and joined the Medical Foundation of Buffalo (renamed in 1994 the Hauptman-Woodward Medical Research Institute), later serving as research director and president.

Hauptman and Karle devised mathematical equations to extract phase information from the intensity of spots resulting from the diffraction of X-rays deflected off crystals. Their equations made it possible to pinpoint the location of atoms within the crystal’s molecules based upon an analysis of the intensity of the spots. Their method was neglected for a number of years after its publication in about 1949, but gradually crystallographers began using it to determine the three-dimensional structure of thousands of small biological molecules, including those of many hormones, vitamins, and antibiotics. Before Hauptman and Karle developed their method, it took about two years to deduce the structure of a simple biological molecule, but by the 1980s, using powerful computers to perform the complex calculations needed, one could do it in about two days.

Details

Herbert Aaron Hauptman (February 14, 1917 – October 23, 2011) was an American mathematician and Nobel laureate. He pioneered and developed a mathematical method that has changed the whole field of chemistry and opened a new era in research in determination of molecular structures of crystallized materials. Today, Hauptman's direct methods, which he continued to improve and refine, are routinely used to solve complicated structures. It was the application of this mathematical method to a wide variety of chemical structures that led the Royal Swedish Academy of Sciences to name Hauptman and Jerome Karle recipients of the 1985 Nobel Prize in Chemistry.

Life

He was born in to a Jewish family in New York City, the oldest child of Leah (Rosenfeld) and Israel Hauptman. He was married to Edith Citrynell since November 10, 1940, with two daughters, Barbara (1947) and Carol (1950).

He was interested in science and mathematics from an early age which he pursued at Townsend Harris High School, graduated from the City College of New York (1937) and obtained an M.A. degree in mathematics from Columbia University in 1939.

After the war he started a collaboration with Jerome Karle at the Naval Research Laboratory in Washington, D.C., and at the same time enrolled in the Ph.D. program at the University of Maryland, College Park. He received his Ph.D. from the University of Maryland in 1955 in physics, which is part of the University of Maryland College of Computer, Mathematical, and Natural Sciences. This combination of mathematics and physical chemistry expertise enabled them to tackle head-on the phase problem of X-ray crystallography. His work on this problem was criticized because, at the time, the problem was believed unsolvable. By 1955 he had received his Ph.D. in mathematics, and they had laid the foundations of the direct methods in X-ray crystallography. Their 1953 monograph, "Solution of the Phase Problem I. The Centrosymmetric Crystal", contained the main ideas, the most important of which was the introduction of probabilistic methods through a development of the Sayre equation.

In 1970 he joined the crystallographic group of the Medical Foundation of Buffalo of which he was research director in 1972. During the early years of this period he formulated the neighborhood principle and extension concept. These theories were further developed during the following decades.

In 2003, as an atheist and secular humanist, he was one of 22 Nobel laureates who signed the Humanist Manifesto.

Works

Hauptman has authored over 170 publications, including journal articles, research papers, chapters and books. In 1970, Hauptman joined the crystallographic group of the Hauptman-Woodward Medical Research Institute (formerly the Medical Foundation of Buffalo) of which he became research director in 1972. Until his death, he served as president of the Hauptman-Woodward Medical Research Institute as well as research professor in the department of biophysical sciences and adjunct professor in the department of computer science at the University at Buffalo. Prior to coming to Buffalo, he worked as a mathematician and supervisor in various departments at the Naval Research Laboratory from 1947. He received his B.S. from City College of New York, M.S. from Columbia University and Ph.D. from the University of Maryland, College Park.

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#12 Re: This is Cool » Miscellany » 2024-05-18 14:58:48

2156) Mango Juice

Summary

Mangoes, indigenous to India, Pakistan, Bangladesh and Southeast Asia, areis known for itstheir delectable taste and flavour. Grown across numerous varieties, the sultan of summer contains many useful nutrients that keep one healthy, content and cheerful. From the youngest to the oldest in the family, mango juice benefits all across ages. No wonder, it has been titled, the king of fruits.

Mango continues its legacy to remain in the top charts of every Indian household. Considered the national fruit of our country, it is known for its finger licking taste, beautiful odour, usefulness in rituals and providing shelter and shadow to human and animals. Apart from India, Mango is also the national fruit of Pakistan and Philippines. In Bangladesh, a mango tree is considered to be the national tree. The popularity of this fruit is always at its peak for the innumerable mango fruit benefits.

Details

Mango juice is just what it sounds like, juice made from mangos. The liquid from mangos can be pretty thick – if you’ve ever drank a can of mango nectar, you know what I mean. So to make mango juice, we add water to achieve an authentic “juice” consistency.

Recipe Ingredients

Mangos – Sweet and fleshy, this fruit is great to snack on, but it also makes a fantastic drink!
Sugar – This ingredient is optional, but you can incorporate it to dial up the sweetness if you want to.
Mint Leaves – This herb makes for a pretty garnish and is also the secret to my perfect sugar syrup. ?

How to Make Mango Juice

Start the Simple Syrup – Combine water, sugar, and mint leaves in a small saucepan. Bring to a boil, stirring until sugar dissolves. Simmer for one minute. Remove from the heat and let syrup steep for about 30 minutes.

Peel and Slice Mango – Slice the sides along the mango seed. Cut the mango flesh in a grid-like pattern without going through the mango skin. Detach the flesh from the skin with a large spoon and scoop the cubes out. For more tips on doing this step, see my guide on how to cut a mango.

Puree – Transfer the mango flesh and water to a blender or food processor and blend until smooth.

Finishing Touches – Pour the mango juice into a jar. Next, add the sugar syrup to taste. This step is optional, and the amount of sugar syrup you use is entirely up to you. Stir to combine.

Serve with ice cubes and garnish with mint leaves. Breathe deeply and enjoy!!!

Recipe Variations

Make your mango juice extra tropical by substituting the water with coconut water, orange juice, pineapple juice, or any other juice you love.

To make mango nectar instead of juice, leave the water out and only add sugar syrup. The finished product will be a much thicker and sweeter mango drink.

Make a mango smoothie by adding milk instead of water. Creamy and delicious! ?

Tips and Tricks

* With this mango juice recipe, consistency is totally up to you. Add more water if you would like a thinner juice.
* If you choose to add sugar syrup, do so a little at a time and taste the juice as you go until you reach your desired sweetness level. You can always add more sugar syrup if it isn’t sweet enough, but it will be hard to take it out if you add too much.

Make-Ahead Instructions

Mango juice stays fresh in the fridge for 3-5 days, so you can make it a few days in advance if you’d like. You can even freeze mango juice. It will keep good for three months in the freezer, so technically, you can make it way in advance if you’d like.

Serving and Storage Instructions

Serve mango juice cold! Add a few cubes of ice, give the glass a stir, and serve it up right away.

Store mango juice in a pitcher or jar with a lid in the fridge. You can freeze mango juice in any airtight container. I like to use ziplock bags personally.

When you are ready to use frozen mango juice, simply take it out of the freezer the night before. Once it’s thawed, you can serve it immediately.

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#14 Re: Dark Discussions at Cafe Infinity » crème de la crème » 2024-05-17 18:43:28

1452) César Milstein

Gist

The immune system includes cells, lymphocytes and antibodies that neutralize substances foreign to the body, or antigens. We have millions of different antibodies, but each cell can produce only one kind of antibody. Sometimes a cell that forms a certain kind of antibody grows abnormally and a tumor is formed. In 1975 Cesar Milstein and George Köhler developed a method for combining such tumor cells with cells that are immune to a certain antigen so that antibodies of the same type—monoclonal antibodies—can be produced.

Summary

César Milstein (born October 8, 1927, Bahía Blanca, Argentina—died March 24, 2002, Cambridge, England) was an Argentine-British immunologist who in 1984, with Georges Köhler and Niels K. Jerne, received the Nobel Prize for Physiology or Medicine for his work in the development of monoclonal antibodies.

Milstein attended the Universities of Buenos Aires (Ph.D., 1957) and Cambridge (Ph.D., 1960) and was on the staff of the National Institute of Microbiology in Buenos Aires (1957–63). Thereafter he was a member of the Medical Research Council Laboratory of Molecular Biology, Cambridge, England, and held dual Argentine and British citizenship.

Artificial production of monoclonal antibodiesThe technique involves fusing certain myeloma cells (cancerous B cells), which can multiply indefinitely but cannot produce antibodies, with plasma cells (noncancerous B cells), which are short-lived but produce a desired antibody. The resulting hybrid cells, called hybridomas, grow at the rate of myeloma cells but also produce large amounts of the desired antibody. In this way researchers obtain large quantities of antibody molecules that all react against the same antigen. The essential production steps are shown here. In step 2, HGPRT is hypoxanthineguanine phosphoribosyltransferase, an enzyme that allows cells to grow on a medium containing HAT, or hydroxanthine, aminopterin, and thymidine. As shown in step 4, only hybridomas can live in the HAT medium; unfused myeloma cells, lacking HGPRT, die in the medium, as do unfused plasma cells, which are naturally short-lived.
Milstein studied antibodies—the proteins produced by mature B lymphocytes (plasma cells) that help the body eliminate infections. In his research he used myeloma cells, which are cancerous forms of plasma cells that multiply indefinitely. In 1975, working with Köhler, who was a postdoctoral fellow at Cambridge, Milstein developed one of the most powerful tools of molecular biology: monoclonal antibody production, a technique that allows researchers to construct cells that produce great quantities of identical (monoclonal) antibodies, all targeted to recognize the same antigen. The procedure involves fusing long-lived myeloma cells that do not produce antibodies with short-lived plasma cells that produce a specific antibody. The resulting hybrid cells, called hybridomas, combine the longevity of the myeloma cell with the ability to produce a specific antibody and so are able to produce potentially unlimited amounts of the desired antibody. Monoclonal antibodies have a wide variety of clinical and research applications; for example, they are used in pregnancy tests, in diagnosing viral and bacterial diseases, and in blood cell and tissue typing.

Milstein received the Royal Medal (1982) and the Copley Medal (1989) from the Royal Society of London. In 1983 he became head of the Protein and Nucleic Acid Chemistry Division at the Medical Research Council laboratory. In 1994 Milstein was made a Companion of Honour.

Details

César Milstein, (8 October 1927 – 24 March 2002) was an Argentine biochemist in the field of antibody research. Milstein shared the Nobel Prize in Physiology or Medicine in 1984 with Niels Kaj Jerne and Georges J. F. Köhler for developing the hybridoma technique for the production of monoclonal antibodies.

Biography

Milstein was born in Bahía Blanca, Argentina. His parents were Máxima (Vanarks) and Lázaro Milstein, a Jewish Ukrainian immigrant. He graduated from the University of Buenos Aires and obtained a PhD under Professor Stopani (Professor of Biochemistry). Later he became a member of the Medical Research Council Laboratory of Molecular Biology, Cambridge, England; he acquired British citizenship and had dual British-Argentinian nationality. In 1956, he received an award from the Sociedad Argentina de Investigation eon Bio Quimica (SAIB) for his work on enzyme kinetics with the enzyme aldehyde dehydrogenase. In 1958, funded by the British Council, he joined the Biochemistry Department at the University of Cambridge to work for a PhD under Malcolm Dixon on the mechanism of metal activation of the enzyme phosphoglucomutase. During this work, he collaborated with Frederick Sanger, whose group he joined with a short-term Medical Research Council appointment.

Career

The major part of Milstein's research career was devoted to studying the structure of antibodies and the mechanism by which antibody diversity is generated. It was as part of this quest that, in 1975, he worked with Georges Köhler (a postdoctoral fellow in his laboratory) to develop the hybridoma technique for the production of monoclonal antibodies—a discovery recognized by the award of the 1984 Nobel Prize for Physiology or Medicine. This discovery led to an enormous expansion in the exploitation of antibodies in science and medicine. The term hybridoma was coined by Leonard Herzenberg during his sabbatical in Milstein's laboratory between 1976 and 1977.

Milstein himself made many major contributions to improvements and developments in monoclonal antibody technology—especially in the use of monoclonal antibodies to provide markers that allow distinction between different cell types. In collaboration with Claudio Cuello, he helped lay the foundation for the use of monoclonal antibodies as probes for the investigation of the pathological pathways in neurological disorders as well as many other diseases. Milstein and Cuello's work also enabled the use of monoclonal antibodies to enhance the power of immuno-based diagnostic tests. In addition, Milstein foresaw the potential wealth of ligand-binding reagents that could result from applying recombinant DNA technology to monoclonal antibodies and inspired the development of the field of antibody engineering, which was to lead to safer and more powerful monoclonal antibodies for use as therapeutics.

Milstein's early work on antibodies focused on their diversity at the amino acid level, as well as on the disulfide bonds by which they were held together. Part of this work was done in collaboration with his wife, Celia. The emphasis of his research then shifted towards the mRNA encoding antibodies, where he was able to provide the first evidence for the existence of a precursor for these secreted polypeptides that contained a signal sequence. The development of the hybridoma technology coupled to advances in nucleic acid sequencing allowed Milstein to chart the changes that occurred in antibodies following antigen encounter. He demonstrated the importance of somatic hypermutation of immunoglobulin V genes in antibody affinity maturation. In this process, localized mutation of the immunoglobulin genes allows the production of improved antibodies, which make a major contribution to protective immunity and immunological memory. Much of his work in later years was devoted to characterizing this mutational process with a view to understanding its mechanism. He contributed a manuscript for publication on this topic less than a week before he died.

Quite apart from his own achievements, Milstein acted as a guide and inspiration to many in the antibody field, as well as devoting himself to assisting science and scientists in less developed countries. Milstein patented the production of monoclonal antibodies, and held three other patents.

Awards and honours

In addition to the Nobel Prize in 1984, Milstein was elected a Fellow of the Royal Society (FRS) in 1975, was a fellow of Darwin College, Cambridge, from 1980 to 2002, awarded the Louisa Gross Horwitz Prize from Columbia University in 1980, won the Copley Medal in 1989, and became a Member of the Order of the Companions of Honour in 1995. In 1993, the Argentinian Konex Foundation granted him the Diamond Konex Award, one of the most prestigious cultural awards of Argentina, as the most important scientist in the last decade of his country.

Personal life

Milstein died early on 24 March 2002, in Cambridge, England, at age 74, as a result of a heart condition that he had suffered from for many years. His wife died in 2020 aged 92.

The film "Un fueguito, la historia de César Milstein" was released in 2010. Directed by Ana Fraile, the film was awarded Best Documentary by the Academy of Film in Argentina.

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#15 Jokes » Mushroom Jokes - III » 2024-05-17 18:08:18

Jai Ganesh
Replies: 0

Q: Where do mushrooms come from?
A: Mushy rooms.
* * *
Q: What's the only room you can't have in your house?
A: A mushroom.
* * *
Q: What did the mushroom say to the other mushroom?
A: There's not that mush room in here.
* * *
Q: What do you get if you cross a toadstool and a full suitcase?
A: Not mushroom for your holiday clothes!
* * *
Q: Did you hear the joke about the fungus?
A: I could tell it to you, but it might need time to grow on you.
* * *

#16 Dark Discussions at Cafe Infinity » Chances Quotes - III » 2024-05-17 16:42:23

Jai Ganesh
Replies: 1

Chances Quotes - III

1. I am willing to take chances. I miss more, but I am going for it. - Mats Wilander

2. The first point is always to believe in it when you go on court and then you have the chances to win. - Martina Hingis

3. To be happy, to make other people happy, to get into movie production more and probably to give some other people the chances that I had, to carry on enjoying being a mum and never to stop having flowers bought for me. I've still got a long way to go. - Sharon Stone

4. As years go by, chances of winning here are getting slimmer. That's just a matter of fact. It does get tougher, but it's possible, there's a tiny little chance. - Stefan Edberg

5. Above all, film is a business... Independence is a really cool thing as you can be a bit more bold, and take a few more chances with what you do. - Mel Gibson

6. I think I could look back through the past few years at missed opportunities and stuff, but one thing I have learned is not to dwell on missed chances or times where you have failed. - Michael Chang

7. I knew I was the second-best tennis player in the state of Florida and No. 8 in the United States of America when I was 12 years old and I couldn't tell you what I was in baseball, but I liked my chances in tennis of getting a scholarship to college. - Jim Courier

8. I guess I've always been attracted to people who stand out as individuals - people who are adventurous and take chances. - Carmen Electra.

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#17 Re: Jai Ganesh's Puzzles » General Quiz » 2024-05-17 16:02:08

Hi,

#9801. What does the term in Chemistry Racemic mixture or racemate mean?

#9802. What does the term in Chemistry Radical mean?

#18 Re: Jai Ganesh's Puzzles » Doc, Doc! » 2024-05-17 15:30:30

Hi,

#2571. What does the medical term 'Diabetic neuropathy' mean?

#22 Re: This is Cool » Miscellany » 2024-05-17 14:11:05

2155) Geometry Box

Summary

A geometry box is a set of various instruments required for basic geometric diagrams and graphs. It consists of instruments like a compass, divider, ruler, set squares, and protractor. These instruments are crucial for geometry classes.

Let us understand the usage of various instruments in the geometry box.

* A ruler is used to measure the length and width of an object. It is also used to draw lines as per the needs.
* The next crucial instrument in a geometry box is a compass. Math Students can learn to draw circles using a compass.
* Another crucial tool is a divider that measures the distance between two points. The significant advantage of this tool is that it gives accurate results.
* A protractor is a tool to measure the angle between two intersecting lines.
* The last set of tools includes set-squares. The box has two set squares of triangular shape.

These tools are significant for students learning geometry. Geometry tools are of great help for people in the design field. The tools let you design blueprints in the absence of a computer. Moreover, the instruments ensure that your angles and distances are on point.

Geometry plays a crucial role in the life of every student. You can draw accurate angles and lines using the geometry box. However, learning the right tricks and tips are crucial for accurate measurements. Students can use the best geometry sets to make the right measurements. The tools are vital when appearing for mathematics tips classes and examinations. Students can practice sums on geometry using worksheets and online learning materials.

Details

Geometry box, also known as a math set or a drawing kit, is a collection of essential tools used for various geometrical and mathematical tasks. It is commonly used by students, architects, engineers, artists, and anyone involved in drawing, designing, or mathematical work. A typical geometry box contains several tools neatly organized in a compact box or case. The specific contents of a geometry box can vary, but some common items typically found in a geometry box include:

Compass: A tool used for drawing circles and arcs of various sizes.

Divider: Similar to a compass but with two pointed ends, used for measuring and transferring distances.

Protractor: A semi-circular instrument used for measuring angles in degrees.

Set Square (Triangle): Triangular rulers with different angles (typically 30°, 45°, and 60°) used for drawing lines at specific angles.

Scale Ruler: A ruler with various scales (e.g., centimeters, millimeters, inches) for measuring and drawing accurate straight lines.

Pencil: Essential for drawing and sketching.

Eraser: Used to remove pencil marks and mistakes.

Sharpener: For sharpening pencils.

What is Geometry Box?

A geometry box is a set of basic equipment required for regular use in basic geometrical diagram and graphs. The basic geometry box consists of a compass, a 15cm ruler, a divider, 2 set squares and a protractor.

A geometry box, also known as a geometry set or a math set, is a collection of essential tools used for various geometrical and mathematical tasks. It is a common tool used by students, artists, architects, engineers, and anyone involved in drawing, designing, or mathematical work.

What is the use of instruments in geometry box?

The instruments in a geometry box serve specific purposes and are used to perform various geometrical and mathematical tasks. Each tool has its unique function, and together, they help students, artists, architects, engineers, and others to draw accurate shapes, measure angles, and perform other geometric operations. Here are the uses of some common instruments found in a geometry box:

* Compass: The compass is used to draw circles and arcs of various sizes. It consists of two arms—one with a pointed end to act as the center and the other with a pencil to draw the circle or arc.
* Divider: Similar to a compass, the divider has two pointed ends and is used to measure and transfer distances. It helps in replicating lengths or distances on paper.
* Protractor: The protractor is a semi-circular instrument with a scale of angles in degrees. It is used to measure and draw angles accurately.
* Set Square (Triangle): Set squares are triangular rulers with different angles (30°, 45°, and 60°). They are used for drawing lines at specific angles and constructing geometric shapes.
* Scale Ruler: The scale ruler has various scales (e.g., centimeters, millimeters, inches) and is used for measuring lengths and drawing straight lines of specific lengths.

Who invented geometry box?

The concept of a geometry box, as we know it today, is not attributed to a single inventor. Instead, it evolved over time as various tools used for geometric and mathematical tasks were developed and organized into a single kit.

The individual components of a geometry box, such as compasses, rulers, and protractors, have a long history of development, and their origins can be traced back to ancient civilizations. For example:

Geometric Tools: Description And Uses - Maths

Geometric tools are essential instruments used in mathematics to aid in drawing precise geometric shapes, measuring angles, and performing various mathematical operations. These tools are commonly found in geometry boxes or math sets and are used by students, mathematicians, engineers, architects, artists, and other professionals working with geometric concepts. Here are some common geometric tools, along with their descriptions and uses in mathematics:

* Compass: A compass consists of two arms, one with a pointed end and the other with a pencil. It is used to draw circles and arcs of various sizes. In geometry, circles and arcs are fundamental shapes used in constructions and proofs.
* Divider: Similar to a compass, a divider has two pointed ends and is used to measure and transfer distances. It helps in replicating lengths or distances on paper accurately.
* Protractor: A protractor is a semi-circular instrument with a scale of angles in degrees. It is used to measure and draw angles precisely. Protractors are crucial for understanding angles and angle measurements in geometric shapes.
* Set Square (Triangle): Set squares are triangular rulers with different angles (usually 30°, 45°, and 60°). They are used for drawing lines at specific angles and constructing geometric shapes, such as triangles, squares, and hexagons.
* Scale Ruler: A scale ruler has various scales (e.g., centimeters, millimeters, inches) and is used for measuring lengths and drawing straight lines of specific lengths. Scale rulers help maintain proportional accuracy in drawings.

stellar-mathematical-instrument-box-faber-castell-original-imafm7jt36evjvkv.jpeg?q=70&crop=false

#24 This is Cool » Hard Disk Drive » 2024-05-16 21:17:59

Jai Ganesh
Replies: 0

Hard Disk Drive

Summary

HDD stands for Hard Disk Drive. Hard disc, hard drive, and fixed disc are other names for HDD. A hard disc drive (HDD) is a type of data storage device that uses magnetic media to store digital information and rotational platters to retrieve it. Hard drives are the primary storage component of a computer system. Non-volatile memory is present in an electromechanical device. HDDs are used in computers, mobile devices, and consumer technology. They can store operating systems and vast systems of data as well.

Hard disc drives, in particular, regulate the read and write operations of the hard disc on which the files are stored. In a computer, HDDs are either implemented as the primary storage device or as a backup storage device.

They are frequently located in the drive bay and linked to the motherboard using cables in various formats, including Advanced Technology Attachment (ATA), Serial ATA, Parallel ATA, and Small Computer System Interface (SCSI). A power supply device is also linked to the HDD, allowing it to continue to save data even when the power is turned off.

Although a hard drive and a hard disc are distinct objects that are packed together as a unit, either terminology can be used to refer to the entire unit.

Details

A computer hard disk drive (HDD) is a non-volatile data storage device. Non-volatile refers to storage devices that maintain stored data when turned off. All computers need a storage device, and HDDs are just one example of a type of storage device.

HDDs are usually installed inside desktop computers, mobile devices, consumer electronics and enterprise storage arrays in data centers. They can store operating systems, software programs and other files using magnetic disks.

More specifically, hard disk drives control the reading and writing of the hard disk that provides data storage. HDDs are used either as the primary or secondary storage device in a computer. They are commonly found in the drive bay and are connected to the motherboard via an Advanced Technology Attachment (ATA), Serial ATA, parallel ATA or Small Computer System Interface (SCSI) cable, among other formats. The HDD is also connected to a power supply unit and can keep stored data while powered down.

A hard disk drive -- often shortened to hard drive -- and hard disk are not the same things, but they are packaged as a unit and either term can refer to the whole unit.

Why do computers need hard disks?

Storage devices like hard disks are needed to install operating systems, programs and additional storage devices, and to save documents. Without devices like HDDs that can retain data after they have been turned off, computer users would not be able to store programs or save files or documents to their computers. This is why every computer needs at least one storage device to permanently hold data as long as it is needed.

How do hard disk drives work?

Most basic hard drives consist of several disk platters -- a circular disk made of either aluminum, glass or ceramic -- that are positioned around a spindle inside a sealed chamber. The platter spins with a motor that is connected to the spindle. The chamber also includes the read/write heads that magnetically record information to and from tracks on the platters using a magnetic head. The disks also have a thin magnetic coating on them.

The motor spins the platters at up to 15,000 rotations per minute. As the platters spin, a second motor controls the position of the read and write heads that magnetically record and read information on each platter.

Hard disk drive storage capacity

Some of the most common storage drive capacities include the following:

* 16 GB, 32 GB and 64 GB. This range is among the lowest for HDD storage space and is typically found in older and smaller devices.
* 128 GB and 256 GB. This range is generally considered an entry point for HDD devices such as laptops or computers.
* 500 GB, 1 TB and 2 TB. Around 500 GB and above of HDD storage is typically considered decent for an average user. Users can most likely store all their music, photos, videos and other files with this much space. Individuals with games that take up a lot of space should find 1 TB to 2 TB of HDD space suitable.
* More than 2 TB. Anything over 2 TB of HDD space is suitable for users who work with high-resolution files, who need to store or house a large amount of data, or who want to use that space for backup and redundancy.

Currently, the highest capacity HDD is 20 TB. However, an HDD actually has less space than advertised, as the operating system, file system structures and some data redundancy procedures use a portion of that space.

Hard drive components and form factors

Hard disk drive components include the spindle, disk platter, actuator, actuator arm and read/write head. Even though the term can refer to the unit as a whole, the term hard disk is the set of stacked disks -- in other words, the part of the HDD that stores and provides access to data on an electromagnetically charged surface.

The HDD form factor refers to the physical size or geometry of the data storage device. HDD form factors follow a set of industry standards that govern their length, width and height, as well as the position and orientation of the host interface connector. Having an industry-standard form factor helps determine a common compatibility with different computing devices.

The most common form factors for HDDs in enterprise systems are 2.5-inch and 3.5-inch -- also known as small form factor (SFF) and large form factor (LFF). The 2.5-inch and 3.5-inch measurements represent the approximate diameter of the platter within the drive enclosures.

While there are other form factors, by 2009, manufacturers discontinued the development of products with 1.3-inch, 1-inch and 0.85-inch form factors. The falling price of flash made these other form factors almost obsolete. It is also important to note that while nominal sizes are in inches, actual dimensions are specified in millimeters.

Many solid-state drives (SSDs) are also designed for the HDD form factor. SSDs that fit into the same slots as HDDs generally use the SATA or serial-attached SCSI (SAS) interface to transfer data to and from the host computing system.

What are external HDDs?

Most HDDs are found internally in a computer and work as stated above. However, individuals can also purchase external hard drives. External hard drives can be used to expand the storage capacity of a computer or to act as a portable device to back up data. External drives connect to a computer or device through interfaces like USB 2.0, USB-C or with External SATA (eSATA). External hard drives may also have slower data transfer rates compared to internal HDDs.

The main advantage of an external hard drive, aside from being able to expand a device's storage space, includes being portable. Users can store data from multiple devices and physically bring that data with them wherever they go.

Common hard disk errors

Hard disks can fail for all sorts of reasons. However, failures generally fall into the following six broad categories.

* Electrical failure occurs when, for example, a power surge damages a hard disk's electronic circuitry, causing the read/write head or circuit board to fail. If a hard disk powers on but cannot read and write data or boot, it is likely that one or more of its components has suffered an electrical failure.
* Mechanical failure can be caused by wear and tear, as well as by a hard impact, like a hard drop. This may cause, among other things, the read/write drive head to hit a rotating platter, causing irreversible physical damage.
* Logical failure results when the hard disk's software is compromised or ceases to run properly. All sorts of data corruption can lead to a logical failure. This includes corrupted files, malware and viruses, improperly closing an application or shutting down a computer, human error or accidentally deleting files that are critical to hard disk functionality.
* Bad sector failure can occur when the magnetic media on a hard disk's rotating platter is misaligned, resulting in a specific area on the platter becoming inaccessible. Bad sectors are common and often limited when they occur. Over time, however, the number of bad sectors can increase, eventually leading to a system crash, inaccessible files or the hanging or lagging of the operation of a hard disk.
* Firmware failure happens when the software that performs the maintenance tasks on a drive and enables the hard disk to communicate with a computer becomes corrupted or stops working properly. This type of failure can lead to the disk freezing during bootup or the computer a hard disk is connected to not recognizing or misidentifying it.
* Multiple unknown failures that accumulate over time can also occur. For example, an electrical problem could lead to a mechanical failure, such as a read/write head crash. It might also lead to a logical failure, resulting in several bad sectors developing on the hard disk platters.

History of hard disk drives

The hard disk was created in 1953 by engineers at IBM who wanted to find a way to provide random access to high capacities of data at a low cost. The disk drives developed were the size of refrigerators, could store 3.75 MB of data and began shipping in 1956. Memorex, Seagate Technology and Western Digital were other early vendors of hard disk drive technology.

Hard disk drive form-factor size has continued to decrease as the technology evolves. By the mid-1980s, 3.5-inch and 2.5-inch form factors were introduced and became a standard in personal computers.

Hard disk drive density has increased since the technology was first developed. The first hard disk drives could store megabytes of data, while today their storage capacity is in the terabyte range. Hitachi Global Storage Technologies (HGST) -- now a Western Digital brand -- released the first 1 TB hard drives in 2007. In 2015, HGST announced the first 10 TB hard drive. And in 2021, Western Digital unveiled two 20 TB HDDs.

Additional Information

A hard disk drive (HDD), hard disk, hard drive, or fixed disk, is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data when powered off. Modern HDDs are typically in the form of a small rectangular box.

Hard disk drives were introduced by IBM in 1956, and were the dominant secondary storage device for general-purpose computers beginning in the early 1960s. HDDs maintained this position into the modern era of servers and personal computers, though personal computing devices produced in large volume, like mobile phones and tablets, rely on flash memory storage devices. More than 224 companies have produced HDDs historically, though after extensive industry consolidation, most units are manufactured by Seagate, Toshiba, and Western Digital. HDDs dominate the volume of storage produced (exabytes per year) for servers. Though production is growing slowly (by exabytes shipped[6]), sales revenues and unit shipments are declining, because solid-state drives (SSDs) have higher data-transfer rates, higher areal storage density, somewhat better reliability, and much lower latency and access times.

The revenues for SSDs, most of which use NAND flash memory, slightly exceeded those for HDDs in 2018. Flash storage products had more than twice the revenue of hard disk drives as of 2017. Though SSDs have four to nine times higher cost per bit, they are replacing HDDs in applications where speed, power consumption, small size, high capacity and durability are important. As of 2019, the cost per bit of SSDs is falling, and the price premium over HDDs has narrowed.

The primary characteristics of an HDD are its capacity and performance. Capacity is specified in unit prefixes corresponding to powers of 1000: a 1-terabyte (TB) drive has a capacity of 1,000 gigabytes, where 1 gigabyte = 1 000 megabytes = 1 000 000 kilobytes (1 million) = 1 000 000 000 bytes (1 billion). Typically, some of an HDD's capacity is unavailable to the user because it is used by the file system and the computer operating system, and possibly inbuilt redundancy for error correction and recovery. There can be confusion regarding storage capacity, since capacities are stated in decimal gigabytes (powers of 1000) by HDD manufacturers, whereas the most commonly used operating systems report capacities in powers of 1024, which results in a smaller number than advertised. Performance is specified as the time required to move the heads to a track or cylinder (average access time), the time it takes for the desired sector to move under the head (average latency, which is a function of the physical rotational speed in revolutions per minute), and finally, the speed at which the data is transmitted (data rate).

The two most common form factors for modern HDDs are 3.5-inch, for desktop computers, and 2.5-inch, primarily for laptops. HDDs are connected to systems by standard interface cables such as SATA (Serial ATA), USB, SAS (Serial Attached SCSI), or PATA (Parallel ATA) cables.

Mechanical-Hard-Drive.jpg?q=50&fit=contain&w=1140&h=&dpr=1.5

#25 Re: Dark Discussions at Cafe Infinity » crème de la crème » 2024-05-16 19:16:02

1451) Klaus von Klitzing

Gist

If an electrical current flows lengthwise through a metal band and a magnetic field is placed against the surface of the band at a right angle, a charge arises diagonally in the band. Known as the Hall effect, it comes about because the movement of the electrons is deflected by the magnetic field. In 1980, Klaus von Klitzing discovered the quantum Hall effect in an interface between a metal and a semiconductor in a very clean material. In this effect, changes in the magnetic field result in changes in what is known as Hall conductance that vary in steps of whole-number multiples of a constant.

Summary

Klaus von Klitzing (born June 28, 1943, Schroda [Sroda], German-occupied Poland) is a German physicist who was awarded the Nobel Prize for Physics in 1985 for his discovery that under appropriate conditions the resistance offered by an electrical conductor is quantized; that is, it varies by discrete steps rather than smoothly and continuously.

At the end of World War II, Klitzing was taken by his parents to live in West Germany. He attended the Technical University of Brunswick, graduating in 1969, and then earned a doctorate in physics at the University of Würzburg in 1972. In 1980 he became a professor at the Technical University of Munich, and in 1985 he became director of the Max Planck Institute for Solid State Physics in Stuttgart, Ger.

Klitzing demonstrated that electrical resistance occurs in very precise units by using the Hall effect. The Hall effect denotes the voltage that develops between the edges of a thin current-carrying ribbon placed between the poles of a strong magnet. The ratio of this voltage to the current is called the Hall resistance. When the magnetic field is very strong and the temperature very low, the Hall resistance varies only in the discrete jumps first observed by Klitzing. The size of those jumps is directly related to the so-called fine-structure constant, which defines the mathematical ratio between the motion of an electron in the innermost orbit around an atomic nucleus to the speed of light.

The significance of Klitzing’s discovery, made in 1980, was immediately recognized. His experiments enabled other scientists to study the conducting properties of electronic components with extraordinary precision. His work also aided in determining the precise value of the fine-structure constant and in establishing convenient standards for the measurement of electrical resistance.

Details

Klaus von Klitzing (born 28 June 1943, Schroda) is a German physicist, known for discovery of the integer quantum Hall effect, for which he was awarded the 1985 Nobel Prize in Physics.

Education

In 1962, Klitzing passed the Abitur at the Artland-Gymnasium in Quakenbrück, Germany, before studying physics at the Braunschweig University of Technology, where he received his diploma in 1969. He continued his studies at the University of Würzburg at the chair of Gottfried Landwehr, completing his PhD thesis entitled Galvanomagnetic Properties of Tellurium in Strong Magnetic Fields in 1972, and gaining habilitation in 1978.

Research and career

During his career Klitzing has worked at the Clarendon Laboratory at the University of Oxford and the Grenoble High Magnetic Field Laboratory in France (now LNCMI), where he continued to work until becoming a professor at the Technical University of Munich in 1980. He has been a director of the Max Planck Institute for Solid State Research in Stuttgart since 1985.

The von Klitzing constant, RK = h/e^2 = 25812.80745... Ω, is named in honor of Klaus von Klitzing's discovery of the quantum Hall effect, and is listed in the National Institute of Standards and Technology Reference on Constants, Units, and Uncertainty. The inverse of the constant is equal to half the value of the conductance quantum.

More recently, Klitzing's research focuses on the properties of low-dimensional electronic systems, typically in low temperatures and in high magnetic fields.

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