Posts by Jai Ganesh

Jai Ganesh · This is Cool

2477) Photosysthesis

Gist

Photosynthesis is the vital process where plants, algae, and some bacteria use sunlight, water, and carbon dioxide to create their own food (glucose/sugars) and release oxygen, converting light energy into stored chemical energy, forming the base of most food webs and producing atmospheric oxygen. It involves light-dependent reactions (capturing energy in ATP/NADPH using chlorophyll) and light-independent reactions (Calvin Cycle) that use this energy to build sugars, occurring in chloroplasts.

Photosynthesis is the process where plants, algae, and some bacteria use sunlight, water, and carbon dioxide to create their own food (glucose/sugar) and release oxygen as a byproduct, converting light energy into stored chemical energy. This vital process, primarily occurring in chloroplasts, provides the energy and oxygen necessary for most life on Earth.

Summary

Photosynthesis is a system of biological processes by which photopigment-bearing autotrophic organisms, such as most plants, algae and cyanobacteria, convert light energy — typically from sunlight — into the chemical energy necessary to fuel their metabolism. The term photosynthesis usually refers to oxygenic photosynthesis, a process that releases oxygen as a byproduct of water splitting. Photosynthetic organisms store the converted chemical energy within the bonds of intracellular organic compounds (complex compounds containing carbon), typically carbohydrates like sugars (mainly glucose, fructose and sucrose), starches, phytoglycogen and cellulose. When needing to use this stored energy, an organism's cells then metabolize the organic compounds through cellular respiration. Photosynthesis plays a critical role in producing and maintaining the oxygen content of the Earth's atmosphere, and it supplies most of the biological energy necessary for complex life on Earth.

Some organisms also perform anoxygenic photosynthesis, which does not produce oxygen. Some bacteria (e.g. purple bacteria) use bacteriochlorophyll to split hydrogen sulfide as a reductant instead of water, releasing sulfur instead of oxygen, which was a dominant form of photosynthesis in the euxinic Canfield oceans during the Boring Billion. Archaea such as Halobacterium also perform a type of non-carbon-fixing anoxygenic photosynthesis, where the simpler photopigment retinal and its microbial rhodopsin derivatives are used to absorb green light and produce a proton (hydron) gradient across the cell membrane, and the subsequent ion movement powers transmembrane proton pumps to directly synthesize adenosine triphosphate (ATP), the "energy currency" of cells. Such archaeal photosynthesis might have been the earliest form of photosynthesis that evolved on Earth, as far back as the Paleoarchean, preceding that of cyanobacteria (see Purple Earth hypothesis).

While the details may differ between species, the process always begins when light energy is absorbed by the reaction centers, proteins that contain photosynthetic pigments or chromophores. In plants, these pigments are chlorophylls (a porphyrin derivative that absorbs the red and blue spectra of light, thus reflecting green) held inside chloroplasts, abundant in leaf cells. In cyanobacteria, they are embedded in the plasma membrane. In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, producing oxygen gas. The hydrogen freed by the splitting of water is used in the creation of two important molecules that participate in energetic processes: reduced nicotinamide adenine dinucleotide phosphate (NADPH) and ATP.

In plants, algae, and cyanobacteria, sugars are synthesized by a subsequent sequence of light-independent reactions called the Calvin cycle. In this process, atmospheric carbon dioxide is incorporated into already existing organic compounds, such as ribulose bisphosphate (RuBP). Using the ATP and NADPH produced by the light-dependent reactions, the resulting compounds are then reduced and removed to form further carbohydrates, such as glucose. In other bacteria, different mechanisms like the reverse Krebs cycle are used to achieve the same end.

The first photosynthetic organisms probably evolved early in the evolutionary history of life using reducing agents such as hydrogen or hydrogen sulfide, rather than water, as sources of electrons. Cyanobacteria appeared later; the excess oxygen they produced contributed directly to the oxygenation of the Earth, which rendered the evolution of complex life possible. The average rate of energy captured by global photosynthesis is approximately 130 terawatts, which is about eight times the total power consumption of human civilization. Photosynthetic organisms also convert around 100–115 billion tons (91–104 Pg petagrams, or billions of metric tons), of carbon into biomass per year. Photosynthesis was discovered in 1779 by Jan Ingenhousz who showed that plants need light, not just soil and water.

Details

Photosynthesis is the process by which green plants and certain other organisms transform light energy into chemical energy. During photosynthesis in green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy-rich organic compounds.

Importance of photosynthesis

It would be impossible to overestimate the importance of photosynthesis in the maintenance of life on Earth. The Great Oxidation Event, which began about 2.4 billion years ago and was largely driven by the photosynthetic cyanobacteria, raised atmospheric oxygen to nearly 1 percent of present levels over a span of 600 million years, paving the way for the evolution of most forms of multicellular life. Photosynthesis completely transformed Earth’s environment and biosphere. The life-giving process continues to sustain biodiversity since autotrophs are foundational to nearly every food web on the planet. If photosynthesis ceased, there would soon be little food or other organic matter on Earth. Most organisms would disappear, and in time Earth’s atmosphere would become nearly devoid of gaseous oxygen. The only organisms able to exist under such conditions would be the chemosynthetic bacteria, which can utilize the chemical energy of certain inorganic compounds and thus are not dependent on the conversion of light energy.

Energy produced by photosynthesis carried out by plants millions of years ago is responsible for the fossil fuels (i.e., coal, oil, and natural gas) that power industrial society. In past ages, green plants and small organisms that fed on plants increased faster than they were consumed, and their remains were deposited in Earth’s crust by sedimentation and other geological processes. There, protected from oxidation, these organic remains were slowly converted to fossil fuels. These fuels not only provide much of the energy used in factories, homes, and transportation but also serve as the raw material for plastics and other synthetic products. Unfortunately, modern civilization is using up in a few centuries the excess of photosynthetic production accumulated over millions of years. Consequently, the carbon dioxide that has been removed from the air to make carbohydrates in photosynthesis over millions of years is being returned at an incredibly rapid rate. The carbon dioxide concentration in Earth’s atmosphere is rising the fastest it ever has in Earth’s history, and this phenomenon—known as global warming—is expected to have major implications on Earth’s climate.

Evolution of the process

Although life and the quality of the atmosphere today depend on photosynthesis, it is likely that green plants evolved long after the first living cells. When Earth was young, electrical storms and solar radiation probably provided the energy for the synthesis of complex molecules from abundant simpler ones, such as water, ammonia, and methane. The first living cells probably evolved from these complex molecules. For example, the accidental joining (condensation) of the amino acid glycine and the fatty acid acetate may have formed complex organic molecules known as porphyrins. These molecules, in turn, may have evolved further into colored molecules called pigments—e.g., chlorophylls of green plants, bacteriochlorophyll of photosynthetic bacteria, hemin (the red pigment of blood), and cytochromes, a group of pigment molecules essential in both photosynthesis and cellular respiration.

Primitive colored cells then had to evolve mechanisms for using the light energy absorbed by their pigments. At first, the energy may have been used immediately to initiate reactions useful to the cell. As the process for using light energy continued to evolve, however, a larger part of the absorbed light energy probably was stored as chemical energy, to be used to maintain life. Green plants, with their ability to use light energy to convert carbon dioxide and water to carbohydrates and oxygen, are the culmination of this evolutionary process.

The first oxygenic (oxygen-producing) cells probably were the cyanobacteria (blue-green algae), which appeared about two billion to three billion years ago. These microscopic organisms are believed to have greatly increased the oxygen content of the atmosphere, making possible the development of aerobic (oxygen-using) organisms. Cyanophytes are prokaryotic cells; that is, they contain no distinct membrane-enclosed subcellular particles (organelles), such as nuclei and chloroplasts. Green plants, by contrast, are composed of eukaryotic cells, in which the photosynthetic apparatus is contained within membrane-bound chloroplasts. The complete genome sequences of cyanobacteria and higher plants provide evidence that the first photosynthetic eukaryotes were likely the red algae that developed when nonphotosynthetic eukaryotic cells engulfed cyanobacteria. Within the host cells, these cyanobacteria evolved into chloroplasts.

There are a number of photosynthetic bacteria that are not oxygenic (e.g., the sulfur bacteria previously discussed). The evolutionary pathway that led to these bacteria diverged from the one that resulted in oxygenic organisms. In addition to the absence of oxygen production, nonoxygenic photosynthesis differs from oxygenic photosynthesis in two other ways: light of longer wavelengths is absorbed and used by pigments called bacteriochlorophylls, and reduced compounds other than water (such as hydrogen sulfide or organic molecules) provide the electrons needed for the reduction of carbon dioxide.

Additional Information

Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar.

Most life on Earth depends on photosynthesis.The process is carried out by plants, algae, and some types of bacteria, which capture energy from sunlight to produce oxygen (O2) and chemical energy stored in glucose (a sugar). Herbivores then obtain this energy by eating plants, and carnivores obtain it by eating herbivores.

The process

During photosynthesis, plants take in carbon dioxide (CO2) and water (H2O) from the air and soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose. The plant then releases the oxygen back into the air, and stores energy within the glucose molecules.

Chlorophyll

Inside the plant cell are small organelles called chloroplasts, which store the energy of sunlight. Within the thylakoid membranes of the chloroplast is a light-absorbing pigment called chlorophyll, which is responsible for giving the plant its green color. During photosynthesis, chlorophyll absorbs energy from blue- and red-light waves, and reflects green-light waves, making the plant appear green.

Light-dependent Reactions vs. Light-independent Reactions

While there are many steps behind the process of photosynthesis, it can be broken down into two major stages: light-dependent reactions and light-independent reactions. The light-dependent reaction takes place within the thylakoid membrane and requires a steady stream of sunlight, hence the name light-dependent reaction. The chlorophyll absorbs energy from the light waves, which is converted into chemical energy in the form of the molecules ATP and NADPH. The light-independent stage, also known as the Calvin cycle, takes place in the stroma, the space between the thylakoid membranes and the chloroplast membranes, and does not require light, hence the name light-independent reaction. During this stage, energy from the ATP and NADPH molecules is used to assemble carbohydrate molecules, like glucose, from carbon dioxide.

C3 and C4 Photosynthesis

Not all forms of photosynthesis are created equal, however. There are different types of photosynthesis, including C3 photosynthesis and C4 photosynthesis. C3 photosynthesis is used by the majority of plants. It involves producing a three-carbon compound called 3-phosphoglyceric acid during the Calvin Cycle, which goes on to become glucose. C4 photosynthesis, on the other hand, produces a four-carbon intermediate compound, which splits into carbon dioxide and a three-carbon compound during the Calvin Cycle. A benefit of C4 photosynthesis is that by producing higher levels of carbon, it allows plants to thrive in environments without much light or water.

Jai Ganesh · This is Cool

Monaco

Gist

Monaco is famous for its extreme wealth, luxury lifestyle, tax haven status (no income tax for residents), glamorous casinos (like the Monte Carlo Casino), yacht-filled harbors, and high-profile events like the Formula 1 Monaco Grand Prix, attracting the world's rich and famous to its French Riviera location, says TATA AIG, Wikipedia, and Study.com. As the world's second-smallest country, it's a major banking center, a hub for high-end tourism, and home to the ruling Grimaldi family, blending historic charm with modern sophistication.

The Monaco permanent residency card ("Carte de Sejour") allow applicants to live in Monaco indefinitely. Permanent residency is granted on the basis of demonstrating proof of accommodation and proof of financial self-sufficiency.

Summary

Monaco, officially the Principality of Monaco, is a sovereign city-state and microstate in Western Europe. Situated on the French Riviera, it is a semi-enclave bordered by France to the north, east, and west, with the Mediterranean Sea to the south; the Italian region of Liguria is about 15 km (9.3 mi) east. With a population of 38,423 living in an area of 2.08 sq km (0.80 sq mi), Monaco is the second smallest sovereign state in the world, after Vatican City, as well as the most densely populated. It also has the world's shortest national coastline of any non-landlocked nation, at 3.83 km (2.38 mi). Fewer than 10,000 of its residents are Monégasque nationals. Although French is the official language of Monaco, Italian and Monégasque are also widely spoken and understood.

Monaco is governed under a form of semi-constitutional monarchy, with Prince Albert II as head of state, who holds substantial political powers. The prime minister, who is the head of government, can be either a Monégasque or French citizen; the monarch consults with the Government of France before an appointment. Key members of the judiciary are detached French magistrates. The House of Grimaldi has ruled Monaco, with brief interruptions, since 1297. The state's sovereignty was officially recognised by the Franco-Monégasque Treaty of 1861, with Monaco becoming a full United Nations voting member in 1993. Despite Monaco's independence and separate foreign policy, its defence is the responsibility of France, notwithstanding two small military units.

Monaco is recognised as one of the wealthiest and most expensive places in the world. Its economic development was spurred in the late 19th century with the opening of the state's first casino, the Monte Carlo Casino, and a rail connection to Paris. The country's mild climate, scenery, and gambling facilities contributed to its status as a tourist destination and recreation centre for the wealthy. Monaco has become a major banking centre and sought to diversify into the services sector and small, high-value-added, non-polluting industries. Monaco is a tax haven; it has no personal income tax (except for French citizens) and low business taxes. Over 30% of residents are millionaires, with real estate prices reaching €100,000 ($116,374) per square metre in 2018. Monaco is a global hub of money laundering, and in June 2024 the Financial Action Task Force placed Monaco under increased monitoring to combat money laundering and terrorist financing.

Monaco is among the 46 Member States which constitute the Council of Europe. It is not part of the European Union (EU), but participates in certain EU policies, including customs and border controls. Through its relationship with France, Monaco uses the euro as its sole currency. Monaco joined the Council of Europe in 2004 and is a member of the Organisation internationale de la Francophonie (OIF). It hosts the annual motor race, the Monaco Grand Prix, one of the original Grands Prix of Formula One. The local motorsports association gives its name to the Monte Carlo Rally, hosted in January in the French Alps. The principality has a club football team, AS Monaco, which competes in French Ligue 1 and has been French champions on multiple occasions, as well as a basketball team, which plays in the EuroLeague. Monaco is a centre of marine conservation and research, being home to one of the world's first protected marine habitats, an Oceanographic Museum, and the International Atomic Energy Agency Marine Environment Laboratories, the only marine laboratory in the UN system.

Details

Monaco is a sovereign principality located along the Mediterranean Sea in the midst of the resort area of the Côte d’Azur (French Riviera). The city of Nice, France, lies 9 miles (15 km) to the west, the Italian border 5 miles (8 km) to the east. Monaco’s tiny territory occupies a set of densely clustered hills and a headland that looks southward over the Mediterranean. Many unusual features, however, have made Monaco among the most luxurious tourist resorts in the world and have given it a fame far exceeding its size.

Many visitors to Monaco alternate their hours between its beaches and boating facilities, its international sports-car races, and its world-famous Place du Casino, the gambling centre in the Monte-Carlo section that made Monte-Carlo an international byword for the extravagant display and reckless dispersal of wealth. The country has a mild Mediterranean climate with annual temperatures averaging 61 °F (16 °C) and with only about 60 days of rainfall. Monthly average temperatures range from 50 °F (10 °C) in January to 75 °F (24 °C) in August.

Evidences of Stone Age settlements in Monaco are preserved in the principality’s Museum of Prehistoric Anthropology. In ancient times the headland was known to the Phoenicians, Greeks, Carthaginians, and Romans. In 1191 the Genoese took possession of it, and in 1297 the long reign of the Grimaldi family began. The Grimaldis allied themselves with France except for the period from 1524 to 1641, when they were under the protection of Spain. In 1793 they were dispossessed by the French Revolutionary regime, and Monaco was annexed to France. With the fall of Napoleon I, however, the Grimaldis returned; the Congress of Vienna (1815) put Monaco under the protection of Sardinia. The principality lost the neighboring towns of Menton and Roquebrune in 1848 and finally ceded them to France under the terms of the Franco-Monegasque treaty of 1861. The treaty did restore Monaco’s independence, however, and in 1865 a customs union was established between the two countries. Another treaty that was made with France, in 1918, contained a clause providing that, in the event that the Grimaldi dynasty should become extinct, Monaco would become an autonomous state under French protection. A revision to the constitution in 2002 added females and their legitimate children to the line of succession. In 1997 the Grimaldi family commemorated 700 years of rule, and in 1999 Prince Rainier III marked 50 years on the throne. Upon his death in April 2005, he was succeeded by his son, Albert; Albert formally assumed the throne on July 12, 2005. The principality joined the United Nations in 1993. Though not a member of the European Union (EU), Monaco phased out the French franc for the single European currency of the euro by 2002.

Monaco’s refusal to impose income taxes on its residents and on international businesses that have established headquarters in the principality led to a severe crisis with France in 1962. A compromise was reached by which French citizens with less than five years residence in Monaco were taxed at French rates and taxes were imposed on Monegasque companies doing more than 25 percent of their business outside the principality. In the early 21st century, some European nations criticized Monaco’s loose banking regulations, claiming that the principality sheltered tax evaders and money launderers. In 2002 the Organisation for Economic Co-operation and Development (OECD) added Monaco to its “blacklist” of uncooperative tax havens. The principality was removed from the blacklist in 2009 after committing to OECD transparency standards.

Monaco’s constitution of 1911 provided for an elected National Council, but in 1959 Prince Rainier III suspended part of the constitution and dissolved the National Council because of a disagreement over the budget. In 1961 he appointed instead a national assembly. The aforementioned crisis of 1962 with France led him to restore the National Council and to grant a new, liberal constitution. The council comprises 18 members, elected by universal suffrage for a term of five years. Government is carried on by a minister of state (who must be a French citizen) and three state councillors acting under the authority of the prince, who is the official chief of state. Legislative power is shared by the prince and the National Council. Since 1819 the judicial system has been based on that of France; since 1962 the highest judicial authority has been the Supreme Tribunal.

A substantial portion of the government’s revenues comes from taxes on commercial transactions; additional revenue is drawn from franchises on radio, television, and the casino, from state-operated monopolies on tobacco and postage stamps, from sales taxes, and from the taxes imposed since 1962.

Monaco’s chief industry is tourism, and its facilities make it one of Europe’s most luxurious resorts. Once a winter attraction, it now draws summer visitors as well to its beaches and expanded mooring facilities. Business conferences are especially important. The social life of Monte-Carlo revolves around the Place du Casino. The casino was built in 1861, and in 1967 its operations were taken over by the principality. Banking and finance and real estate are other important components of the diverse services sector.

More than one-fourth of Monaco’s population is composed of French citizens, and a smaller but significant number are Italian, Swiss, and Belgian. Only about one-fifth of the population claims Monegasque descent. Most of the people are Roman Catholics. The official language is French.

The four sections, or quartiers, of Monaco are the town of Monaco, or “the Rock,” a headland jutting into the sea on which the old town is located; La Condamine, the business district on the west of the bay, with its natural harbor; Monte-Carlo, including the gambling casino; and the newer zone of Fontvieille, in which various light industries have developed.

In Monaco are the Roman Catholic cathedral, the prince’s Genoese and Renaissance palace, and the Oceanographic Museum of Monaco, built in 1910. The casino itself contains a theater designed by the 19th-century French architect Charles Garnier, which is the home of the Opéra de Monte Carlo. During the 1920s many of the works of the famous Ballets Russes of Serge Diaghilev were given their premieres there. There is also a Monte-Carlo national orchestra. The best known of the automobile events held in the principality are the Monte-Carlo Rally and the Grand Prix de Monaco.

Additional Information

Monaco is the second-smallest independent state in the world. It is a playground for tourists and a haven for the wealthy, the former drawn by its climate and the beauty of its setting and the latter by its advantageous tax regime.

The country - a constitutional monarchy - is surrounded on three sides by France.

Tourism is a major earner for the economy. The country is also a major banking centre and closely guards the privacy of its clients. Monaco does not levy income tax on its residents.

Its sovereignty was officially recognised by the Franco-Monegasque Treaty of 1861, with Monaco becoming a full United Nations voting member in 1993.

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Jai Ganesh · Science HQ

Dura Mater

Gist

The tough outer layer of tissue that covers and protects the brain and spinal cord and is closest to the skull.

The meningeal layer of the dura mater creates several dural folds that divide the cranial cavity into freely communicating spaces. The function of the dural folds is to limit the rotational displacement of the brain. The folds include the following: The falx cerebri is a meningeal projection of dura in the brain.

Dura is the thick outer most layer of the 3 meninges. The thick fibrous dura surrounds, supports and protects the central nervous system (brain and spinal cord). In the cranium the dura forms folds to form partitions of the cranial cavity, and separates in places to form dural venous sinuses.

Summary

The dura mater (or just dura) is the outermost of the three meningeal membranes. The dura mater has two layers, an outer periosteal layer closely adhered to the neurocranium, and an inner meningeal layer known as the dural border cell layer. The two dural layers are for the most part fused together forming a thick fibrous tissue membrane that covers the brain and the vertebrae of the spinal column. But the layers are separated at the dural venous sinuses to allow blood to drain from the brain. The dura covers the arachnoid mater and the pia mater, the other two meninges, in protecting the central nervous system.

At major boundaries of brain regions such as the longitudinal fissure between the hemispheres, and the tentorium cerebelli between the posterior brain and the cerebellum the dura separates, folds and invaginates to make the divisions. These folds are known as dural folds, or reflections.

The dura mater is primarily derived from neural crest cells, with postnatal contributions from the paraxial mesoderm.

Details

The meninges are three layers of connective tissue that surround, support and protect the central nervous system (brain and spinal cord). From superficial to deep these layers are named the dura, arachnoid and pia. The dura mater is a thick, tough, fibrous membrane. It receives blood and nerve supply from the meningeal arteries, veins and nerves.

Cranial dura mater

In the cranium, the dura consists of two layers; an outer periosteal dura and an inner meningeal dura. The periosteal dura is closely attached to the internal surface of the skull bones while the inner meningeal dura is continuous with the dura of the spinal cord. The periosteal dura and meningeal dura are tightly fused together, except in a few places where they separate to form the dural venous sinuses; spaces that collect venous blood from the large veins of the brain. The dural venous sinuses are named as follows; superior sagittal sinus, inferior sagittal sinus, straight sinus, occipital sinus, transverse sinus, sigmoid sinus, marginal sinus, superior petrosal sinus, inferior petrosal sinus, petrosquamous sinus, cavernous sinus, sphenoparietal sinus, intercavernous sinus. The straight, occipital, transverse and superior sagittal sinuses all meet at the confluence of the sinuses. Arachnoid granulations, small tufts of arachnoid, protrude through the dura mater into the dural venous sinuses. They are the site of cerebrospinal fluid absorption into dural venous sinuses. Another feature of cranial dura are the dural folds. These are reflections of the inner meningeal dura which divide the cranium into separate compartments. The four dural folds are the falx cerebri, tentorium cerebelli, falx cerebelli, diaphragma sellae; in brief, they separate the cerebral and cerebellar hemispheres into divisions.

Spinal dura mater

In the spinal cord, only one layer of dura mater is found. Unlike in the cranium, the dura is not closely integrated with the overlying bones. Instead, a space exists between the dura and the vertebral bones known as the epidural space. The inferior aspect of the spinal dural sac is anchored to the coccyx by a thin connective tissue strand called the filum terminale.

Innervation

The innervation of the cranial dura mater is primarily sourced from the trigeminal (CN V) and vagus CN X) nerves, as well as spinal nerves C2/C3.

Trigeminal nerve

Several branches of the trigeminal nerve supply the dura mater:

* The tentorial branch of the ophthalmic nerve (CN V1), also known as the recurrent meningeal branch, supplies much of the supratentorial dura mater (i.e., posterior half of the falx cerebri, calvarial dura and superior surface of the tentorium cerebelli).
* The meningeal branch of the anterior ethmoidal nerve (branch of the nasociliary nerve (ophthalmic nerve)) supplies the central region of the anterior cranial fossa as well as anterior parts of the falx cerebri.
* The meningeal branch of the maxillary nerve (CN V2) provides innervation to the posterior region of the anterior cranial fossa as well as the anterior portion of the middle cranial fossa.
* The meningeal branch of the mandibular nerve (CN V3) supplies the posterolateral parts of the middle cranial fossa, before extending anteriorly to the lateral region of the anterior cranial fossa.

Vagus nerve

The posterior and lateral regions of the posterior cranial fossa and inferior surface of the tentorium cerebelli are all primarily innervated by the meningeal branch of the vagus nerve (which arises from its superior ganglion).

Spinal nerves C2/C3

The central region of the posterior cranial fossa, around the foramen magnum, receives innervation from sensory nerve fibers whose cell bodies are located in the spinal ganglia of spinal nerves C2/C3. The nerves may present as ascending branches of the meningeal branch of these spinal nerves which ascend the vertebral canal into the cranial cavity, via the foramen magnum. Alternatively, communicating branches of spinal nerves C2/C3 may pass to the hypoglossal nerve (CN XII), entering the cranial cavity via the meningeal branch of the hypoglossal nerve (via the hypoglossal canal). Some references occasionally also describe meningeal branches derived from the facial (CN VII) and glossopharyngeal (CN IX) nerves as supplying the posterior cranial fossa, however this remains debated.

Spinal dura

The innervation of the spinal dura mater is derived from a meningeal branch of each spinal nerve. It arises near the division of the spinal nerve into anterior and posterior rami, close to the gray/white rami communicating branches, before coursing through the intervertebral foramen into the vertebral canal.

Additional Information

The brain is an important part of the human body, as it performs vital functions and controls almost all bodily functions. It is protected by a strong framework of bones, called the skull. Besides this bony structure, it is also protected against several kinds of injuries or head traumas by the meninges, which are three-layered membranous structures that help protect the brain parts from damage.

The outermost layer of the meninges is the dura mater. The other two layers are collectively known as the leptomeninges and consist of the arachnoid mater (middle layer) and the pia mater (innermost layer). The dura mater is frequently known as the dura.

The dura protects its vital underlying components with a strong fibrous protective covering. In aspects of compressive impacts due to mass lesions and related edema, the compartmentalization of the brain through the help of dural reflections is especially important. The connection of the dural layers to each other, and the underlying leptomeninges and calvarium, has a huge impact on scientists’ knowledge of the impacts of intracranial injury.

Summary:

* The meninges safeguard the spinal cord and brain from tissue injury and assist the framework of the blood vessels
* Dura mater is on the outermost end of the meninges, situated directly beneath the skull and the bones of the vertebral column
* The dura mater is made up of two layers of connective tissue: the periosteal layer and the meningeal layer
* The periosteal layer lines the inner surface of the cranium’s bones. The periosteum is a dense fibrous membrane that covers the surface areas of bones
* The meningeal layer is found deep within the periosteal layer
* The dura mater has a vascular supply of its own
* The dura mater’s meningeal layer bends towards the inner direction of itself to form 4 structural forms, called the dural reflections
* The 4 dural reflections are: Diaphagma sellae, Falx cerebri, Tentorium cerebelli, and Falx cerebelli
* Dura mater encircles and continues to support the large venous channels (called dural sinuses) that help in carrying the blood from the brain to the heart.
* Haemorrhage, meningitis, and meningiomas are some complications involving the dura mater.

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Jai Ganesh · Dark Discussions at Cafe Infinity

2417) Donald Glaser

Gist:

Life

Donald Glaser was born in Cleveland, Ohio to Russian immigrants. His father was a businessman. After first studying at Case School of Applied Science in Cleveland, he later received his PhD in physics from California Institute of Technology, Pasadena, in 1949. He then moved to the University of Michigan in Ann Arbor, where he carried out the research that led to his Nobel Prize, before moving to the University of California, Berkeley, in 1959. Beginning in the 1960s, Glaser devoted himself to molecular biology. He was married twice and had two children from his first marriage.

Work

Our ability to study the smallest components of our world took a giant leap forward when C.T.R. Wilson invented the cloud chamber, where the trails of charged particles can be observed. Donald Glaser's invention of the bubble chamber in 1952 made it possible to study particles with higher energies. When charged particles rush forward through the chamber filled with a liquid at near-boiling point, they ionize atoms they pass by. When the pressure inside the chamber is then reduced, bubbles form around these charged atoms. The particles' tracks can then be photographed and analyzed.

Summary

Donald A. Glaser (born September 21, 1926, Cleveland, Ohio, U.S.—died February 28, 2013, Berkeley, California) was an American physicist and recipient of the 1960 Nobel Prize for Physics for his invention (1952) and development of the bubble chamber, a research instrument used in high-energy physics laboratories to observe the behaviour of subatomic particles.

After graduating from Case Institute of Technology, Cleveland, in 1946, Glaser attended the California Institute of Technology, Pasadena, where he received a Ph.D. in physics and mathematics in 1950. He then began teaching at the University of Michigan, where he became a professor in 1957.

Glaser conducted research with Nobelist Carl Anderson, who was using cloud chambers to study cosmic rays. Glaser, recognizing that cloud chambers had a number of limitations, created a bubble chamber to learn about the pathways of subatomic particles. Because of the relatively high density of the bubble-chamber liquid (as opposed to the vapour that filled cloud chambers), collisions producing rare reactions were more frequent and were observable in finer detail. New collisions could be recorded every few seconds when the chamber was exposed to bursts of high-speed particles from particle accelerators. As a result, physicists were able to discover the existence of a host of new particles, notably quarks. At the age of 34, Glaser became one of the youngest scientists ever to be awarded a Nobel Prize.

In 1959 Glaser joined the staff of the University of California, Berkeley, where he became a professor of physics and molecular biology in 1964. In 1971 he cofounded the Cetus Corp., a biotechnology company that developed interleukin-2 and interferon for cancer therapy. The firm was sold (1991) to Chiron Corp., which was later acquired by Novartis. In the 1980s Glaser turned to the field of neurobiology and conducted experiments on vision and how it is processed by the human brain.

Details

Donald Arthur Glaser (September 21, 1926 – February 28, 2013) was an American physicist and biologist who received the Nobel Prize in Physics in 1960 for his invention of the bubble chamber.

Personal life

Donald Arthur Glaser was born on September 21, 1926, in Cleveland, Ohio, to Russian Jewish immigrants, Lena and William J. Glaser, a businessman. He enjoyed music and played the piano, violin, and viola. He went to Cleveland Heights High School, where he became interested in physics as a means to understand the physical world. He died in his sleep at the age of 86 on February 28, 2013, in Berkeley, California.

Education and career

Glaser attended Case School of Applied Science (now Case Western Reserve University), where he completed his Bachelor of Science degree in physics and mathematics in 1946. During the course of his education there, he became especially interested in particle physics. He played viola in the Cleveland Philharmonic while at Case, and taught mathematics classes at the college after graduation. He continued on to the California Institute of Technology (Caltech), where he pursued his PhD in physics. His interest in particle physics led him to work with Nobel laureate Carl David Anderson, studying cosmic rays with cloud chambers. He preferred the accessibility of cosmic ray research over that of nuclear physics. While at Caltech he learned to design and build the equipment he needed for his experiments, and this skill would prove to be useful throughout his career. He also attended molecular genetics seminars led by Nobel laureate Max Delbrück; he would return to this field later. Glaser completed his doctoral thesis, The Momentum Distribution of Charged Cosmic Ray Particles Near Sea Level, after starting as an instructor at the University of Michigan in 1949. He received his PhD from Caltech in 1950, and he was promoted to professor at Michigan in 1957 He joined the faculty of UC Berkeley in 1959 as a professor of physics. During this time, his research concerned short-lived elementary particles. The bubble chamber enabled him to observe the paths and lifetimes of the particles. Starting in 1962, Glaser changed his field of research to molecular biology, starting with a project on ultraviolet-induced cancer. In 1964, he was given the additional title of professor of molecular biology. Glaser's position (since 1989) was professor of physics and neurobiology in the graduate school.

Bubble chamber

While teaching at Michigan, Glaser began to work on experiments that led to the creation of the bubble chamber. His experience with cloud chambers at Caltech had shown him that they were inadequate for studying elementary particles. In a cloud chamber, particles pass through gas and collide with metal plates that obscure the scientists' view of the event. The cloud chamber also needs time to reset between recording events and cannot keep up with accelerators' rate of particle production.

He experimented with using superheated liquid in a glass chamber. Charged particles would leave a track of bubbles as they passed through the liquid, and their tracks could be photographed. He created the first bubble chamber with ether. He experimented with hydrogen while visiting the University of Chicago, showing that hydrogen would also work in the chamber.

It has often been claimed that Glaser was inspired to his invention by the bubbles in a glass of beer; however, in a 2006 talk, he refuted this story, saying that although beer was not the inspiration for the bubble chamber, he did experiments using beer to fill early prototypes.

His new invention was ideal for use with high-energy accelerators, so Glaser traveled to Brookhaven National Laboratory with some students to study elementary particles using the accelerator there. The images that he created with his bubble chamber brought recognition of the importance of his device, and he was able to get funding to continue experimenting with larger chambers. Glaser was then recruited by Nobel laureate Luis Alvarez, who was working on a hydrogen bubble chamber at the University of California at Berkeley. Glaser accepted an offer to become a professor of physics there in 1959.

Nobel Prize

Glaser was awarded the 1960 Nobel Prize for Physics for the invention of the bubble chamber. His invention allowed scientists to observe what happens to high-energy beams from an accelerator, thus paving the way for many important discoveries.

Jai Ganesh · Dark Discussions at Cafe Infinity

Colonial Quotes

1. Communists have always played an active role in the fight by colonial countries for their freedom, because the short-term objects of Communism would always correspond with the long-term objects of freedom movements. - Nelson Mandela

2. Why are we, as a nation so obsessed with foreign things? Is it a legacy of our colonial years? We want foreign television sets. We want foreign shirts. We want foreign technology. Why this obsession with everything imported? - A. P. J. Abdul Kalam

3. The skills you need to fight the colonial power and the skills you need to gain independence are not necessarily the same you need to run a country. - Kofi Annan

4. Was it not enough punishment and suffering in history that we were uprooted and made helpless slaves not only in new colonial outposts but also domestically. - Robert Mugabe

5. All the sparrows on the rooftops are crying about the fact that the most imperialist nation that is supporting the colonial regime in the colonies is the United States of America. - Nikita Khrushchev

6. Thankfully, Australia has emerged from its inauspicious colonial beginnings to become a proud nation, a nation that overcame those primeval prejudices. - Rupert Murdoch

7. England was the first true colonial power to use its dominion over a large part of Africa, the Middle East, Asia, Australia, North America, and many Caribbean islands, in the first half of the 20th century. - Fidel Castro

8. Famines were frequent in colonial India and some estimates indicate that 30 to 40 million died out of starvation in Tamil Nadu, Bihar and Bengal during the later half of the 19th century. - M. S. Swaminathan.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#10713. What does the term in Geography Couloir mean?

#10714.. What does the term in Geography Country mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#5909. What does the noun homestead mean?

#5910. What does the adjective homely mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2551. What does the medical term Floaters or eye floaters mean?

Jai Ganesh · Jokes

Q: How do you strike fear into a pie?
A: With a very cherry movie.
* * *
Q: Why were the little cherries upset?
A: Because their parents were in a jam!
* * *
Q: How many grams of protein are in a cherry pi?
A: 3.14159265
* * *
Q: What do you call a fruit that likes to tell jokes?
A: Cherry Seinfeld. Did you hear about the cherry that liked to explode? It was da bomb.
* * *
Q: What do you call a man that can't stop eating cherries whole?
A: A bottomless pit.
* * *

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9835.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6329.

Jai Ganesh · Exercises

Hi,

2686.

Jai Ganesh · Science HQ

Centre of Gravity (Center of Gravity)

Gist

Center of gravity (CG) is the point within an object where its weight is evenly balanced in all directions. Understanding its significance is important because it helps predict how an object will behave when it's moved or supported.

The centre of gravity (CG) of an object is the point at which all of its weight is evenly distributed. It is also known as the centre of mass.

It is important to know the centre of gravity because it predicts the behaviour of a moving body when acted on by gravity. It is also useful in designing static structures such as buildings and bridges. In a uniform gravitational field, the centre of gravity is identical to the centre of mass.

Summary

A body's center of gravity is the point around which the resultant torque due to gravity forces vanishes. Where a gravity field can be considered to be uniform, the center of mass and the center of gravity will be the same. However, for satellites in orbit around a planet, in the absence of other torques being applied to a satellite, the slight variation (gradient) in gravitational field between the parts closer to and further from the planet (stronger and weaker gravity respectively) can lead to a torque that will tend to align the satellite such that its long axis is vertical. In such a case, it is important to make the distinction between the center of gravity and the mass center. Any horizontal offset between the two will result in an applied torque.

The mass center is a fixed property for a given rigid body (e.g., with no slosh or articulation), whereas the center of gravity may, in addition, depend upon its orientation in a non-uniform gravitational field. In the latter case, the center of gravity will always be located somewhat closer to the main attractive body as compared to the mass center, and thus will change its position in the body of interest as its orientation is changed.

In the study of the dynamics of aircraft, vehicles and vessels, forces and moments need to be resolved relative to the mass center. That is true independent of whether gravity itself is a consideration. Referring to the mass center as the center of gravity is something of a colloquialism, but it is in common usage and when gravity gradient effects are negligible, center of gravity and mass center are the same and are used interchangeably.

In physics the benefits of using the center of mass to model a mass distribution can be seen by considering the resultant of the gravity forces on a continuous body.

Details

The centre of gravity, in physics, is an imaginary point in a body of matter where, for convenience in certain calculations, the total weight of the body may be thought to be concentrated. The concept is sometimes useful in designing static structures (e.g., buildings and bridges) or in predicting the behaviour of a moving body when it is acted on by gravity.

In a uniform gravitational field the centre of gravity is identical to the centre of mass, a term preferred by physicists. The two do not always coincide, however. For example, the Moon’s centre of mass is very close to its geometric centre (it is not exact because the Moon is not a perfect uniform sphere), but its centre of gravity is slightly displaced toward Earth because of the stronger gravitational force on the Moon’s near side.

The location of a body’s centre of gravity may coincide with the geometric centre of the body, especially in a symmetrically shaped object composed of homogeneous material. An asymmetrical object composed of a variety of materials with different masses, however, is likely to have a centre of gravity located at some distance from its geometric centre. In some cases, such as hollow bodies or irregularly shaped objects, the centre of gravity (or centre of mass) may occur in space at a point external to the physical material—e.g., in the centre of a tennis ball or between the legs of a chair.

Published tables and handbooks list the centres of gravity for most common geometric shapes. For a triangular metal plate such as that depicted in the figure, the calculation would involve a summation of the moments of the weights of all the particles that make up the metal plate about point A. By equating this sum to the plate’s weight W, multiplied by the unknown distance from the centre of gravity G to AC, the position of G relative to AC can be determined. The summation of the moments can be obtained easily and precisely by means of integral calculus.

The centre of gravity of any body can also be determined by a simple physical procedure. For example, for the plate in the figure, the point G can be located by suspending the plate by a cord attached at point A and then by a cord attached at C. When the plate is suspended from A, the line AD is vertical; when it is suspended from C, the line CE is vertical. The centre of gravity is at the intersection of AD and CE. When an object is suspended from any single point, its centre of gravity lies directly beneath that point.

Additional Information

The center of gravity is a geometric property of any object. The center of gravity is the average location of the weight of an object. We can completely describe the motion of any object through space in terms of the translation of the center of gravity of the object from one place to another, and the rotation of the object about its center of gravity if it is free to rotate. If the object is confined to rotate about some other point, like a hinge, we can still describe its motion. In flight, both airplanes and rockets rotate about their centers of gravity. A kite, on the other hand, rotates about the bridle point. But the trim of a kite still depends on the location of the center of gravity relative to the bridle point, because for every object the weight always acts through the center of gravity.

Determining the center of gravity is very important for any flying object. How do engineers determine the location of the center of gravity for an aircraft which they are designing?

In general, determining the center of gravity (cg) is a complicated procedure because the mass (and weight) may not be uniformly distributed throughout the object. The general case requires the use of calculus which we will discuss at the bottom of this page. If the mass is uniformly distributed, the problem is greatly simplified. If the object has a line (or plane) of symmetry, the cg lies on the line of symmetry. For a solid block of uniform material, the center of gravity is simply at the average location of the physical dimensions.

Jai Ganesh · This is Cool

Itaipu Dam

Gist

The world's largest hydroelectric power plant is on the Paraná River between Paraguay and Brazil. The Itaipú Dam is capable of producing 14,000 megawatts of power. The reservoir behind the dam formed in 1982 and covers 1,350 square kilometers. The entire dam is nearly 8 kilometers long.

The Itaipu Hydroelectric Dam is located on the Paraná River on the border between Brazil and Paraguay. The structure which serves to generate power is about 7.9 km long, with a maximum height of 196 m.

Summary

Itaipú Dam is a hollow gravity dam on the Alto (Upper) Paraná River at the Brazil-Paraguay border. It is located north of the town of Ciudad del Este, Paraguay.

In terms of power output, Itaipú Dam is one of the world’s largest hydroelectric projects. Its 20 massive turbine generators, located in the powerhouse at the base of the dam, are capable of generating 14,000 megawatts of electricity. Built as a joint venture by Paraguay and Brazil, the complex of dams and spillways curves across almost 8 km (5 miles) of the Alto Paraná River. The dam itself, built between 1975 and 1982, is 196 metres (643 feet) high and consists of large concrete segments joined to form a hollow chamber. The upstream face is supported by two buttresses, and the downstream face is a simple concrete slab. It is one of the highest and largest hollow gravity dams in the world. Its reservoir stretches northward for about 160 km (100 miles), and it has totally submerged the formerly spectacular Guaíra Falls.

Details

The Itaipu Dam is a hydroelectric dam on the Paraná River located on the border between Brazil and Paraguay. It is the third-largest hydroelectric dam in the world in terms of produced energy.

The name "Itaipu" was taken from an island that existed near the construction site. In the Guarani language, Itaipu means "the sounding stone." As of 2020, the Itaipu Dam's hydroelectric power plant produced the second-largest amount of electricity of any hydroelectric power plant in the world, with its electricity production being only surpassed by the Three Gorges Dam plant in China. Additionally, Itaipu also holds the 45th largest reservoir in the world.

With its construction completed in 1984, it is a binational undertaking run by Brazil and Paraguay at the border between the two countries, 15 km (9.3 mi) north of the Friendship Bridge. The project ranges from Foz do Iguaçu, in Brazil, and Ciudad del Este in Paraguay, in the south to Guaíra and Salto del Guairá in the north. The installed generation capacity of the plant is 14 GW, with 20 generating units providing 700 MW each with a hydraulic design head of 118 metres (387 ft). In 2016, the plant employed 3038 workers.

Of the twenty generator units currently installed, ten generate at 50 Hz for Paraguay and ten generate at 60 Hz for Brazil. Since the output capacity of the Paraguayan generators far exceeds the load in Paraguay, most of their production is exported directly to the Brazilian side, from where two 600 kV HVDC lines, each approximately 800 kilometres (500 mi) long, carry the majority of the energy to the São Paulo/Rio de Janeiro region where the terminal equipment converts the power to 60 Hz.

Additional Information

The Itaipu Dam is a hydroelectric (making electricity by the movement of water) dam on the Paraná River, on the border between Brazil and Paraguay.

It is listed as one of the Seven Wonders of the Modern World. It is the world's second largest dam behind the Three Gorges Dam and is 7919 metres long and 196 metres high. It is the second-largest power plant in the world by nameplate capacity and the largest by power production in 2015-2016.

The Itaipu Dam is owned by the Brazilian Government.

Jai Ganesh · Dark Discussions at Cafe Infinity

2416) Georg von Békésy

Gist:

Work

Our hearing works because sound waves from the surrounding world are converted in the ear into vibrations in membranes and bones. These are further converted into electrical impulses that are passed on to the brain, resulting in auditory impressions. In a series of studies from 1940 to the 1960s, Georg von Békésy clarified how processes in the cochlea in the inner ear proceed, in part by studying vibrations in membranes with the help of a microscope and sequences of photographs as well as by measuring variations in electrical charges in the receptors.

Summary

Georg von Békésy (born June 3, 1899, Budapest, Hungary—died June 13, 1972, Honolulu, Hawaii, U.S.) was an American physicist and physiologist who received the 1961 Nobel Prize for Physiology or Medicine for his discovery of the physical means by which sound is analyzed and communicated in the cochlea, a portion of the inner ear.

As director of the Hungarian Telephone System Research Laboratory (1923–46), Békésy worked on problems of long-distance communication and became interested in the mechanics of human hearing. At the telephone laboratory, the University of Budapest (1939–46), the Karolinska Institute, Stockholm (1946–47), and Harvard University (1947–66) he conducted intensive research that led to the construction of two cochlea models and highly sensitive instruments that made it possible to understand the hearing process, differentiate between certain forms of deafness, and select proper treatment more accurately.

Since the mid-19th century, it had been known that the vibratory tissue most important for hearing is the basilar membrane, stretching the length of the snail-shaped cochlea and dividing it into two interior canals. Békésy found that sound travels along the basilar membrane in a series of waves, and he demonstrated that these waves peak at different places on the membrane: low frequencies toward the end of the cochlea and high frequencies near its entrance, or base. He discovered that the location of the nerve receptors and the number of receptors involved are the most important factors in determining pitch and loudness.

Békésy became professor of sensory sciences at the University of Hawaii in 1966. His books include Experiments in Hearing (1960) and Sensory Inhibition (1967).

Details

Georg von Békésy (3 June 1899 – 13 June 1972) was a Hungarian-American biophysicist.

By using strobe photography and silver flakes as a marker, he was able to observe that the basilar membrane moves like a surface wave when stimulated by sound. Because of the structure of the cochlea and the basilar membrane, different frequencies of sound cause the maximum amplitudes of the waves to occur at different places on the basilar membrane along the coil of the cochlea. High frequencies cause more vibration at the base of the cochlea while low frequencies create more vibration at the apex.

He concluded that his observations showed how different sound wave frequencies are locally dispersed before exciting different nerve fibers that lead from the cochlea to the brain.

In 1961, he was awarded the Nobel Prize in Physiology or Medicine for his research on the function of the cochlea in the mammalian hearing organ.

Biography

Békésy was born on 3 June 1899 in Budapest, Hungary, as the first of three children (György 1899, Lola 1901 and Miklós 1903) to Sándor Békésy (1860–1923), an economic diplomat, and to his mother Paula Mazaly.

The Békésy family was originally Reformed but converted to Catholicism. His mother, Paula Mazaly (1877–1974) was born in Szagolyca (now Čađavica, Croatia). His maternal grandfather was from Pécs. His father was born in Kolozsvár (now Cluj-Napoca, Romania).

Békésy went to school in Budapest, Munich, and Zürich. He studied chemistry in Bern and received his PhD in physics on the subject: "Fast way of determining molecular weight" from the University of Budapest in 1926.

He then spent one year working in an engineering firm. He published his first paper on the pattern of vibrations of the inner ear in 1928. He was offered a position at Uppsala University by Róbert Bárány, which he declined because of the hard Swedish winters.

Before and during World War II, Békésy worked for the Hungarian Post Office (1923 to 1946), where he did research on telecommunications signal quality. This research led him to become interested in the workings of the ear. In 1946, he left Hungary to follow this line of research at the Karolinska Institute in Sweden.

In 1947, he moved to the United States, working at Harvard University until 1966. In 1962 he was elected a Member of the German Academy of Sciences Leopoldina. After his lab was destroyed by fire in 1965, he was invited to lead a research laboratory of sense organs in Honolulu, Hawaii. He became a professor at the University of Hawaiʻi in 1966 and died in Honolulu.

He became a well-known expert in Asian art. He had a large collection which he donated to the Nobel Foundation in Sweden. His brother, Dr. Miklós Békésy (1903-1980), stayed in Hungary and became a famous agrobiologist who was awarded the Kossuth Prize.

Research

Békésy contributed most notably to our understanding of the mechanism by which sound frequencies are registered in the inner ear. He developed a method for dissecting the inner ear of human cadavers while leaving the cochlea partly intact. By using strobe photography and silver flakes as a marker, he was able to observe that the basilar membrane moves like a surface wave when stimulated by sound. Because of the structure of the cochlea and the basilar membrane, different frequencies of sound cause the maximum amplitudes of the waves to occur at different places on the basilar membrane along the coil of the cochlea. High frequencies cause more vibration at the base of the cochlea while low frequencies create more vibration at the apex.

Békésy concluded from these observations that by exciting different locations on the basilar membrane different sound wave frequencies excite different nerve fibers that lead from the cochlea to the brain. He theorized that, due to its placement along the cochlea, each sensory cell (hair cell) responds maximally to a specific frequency of sound (the so-called tonotopy). Békésy later developed a mechanical model of the cochlea, which confirmed the concept of frequency dispersion by the basilar membrane in the mammalian cochlea.

In an article published posthumously in 1974, Békésy reviewed progress in the field, remarking "In time, I came to the conclusion that the dehydrated cats and the application of Fourier analysis to hearing problems became more and more a handicap for research in hearing," referring to the difficulties in getting animal preparations to behave as when alive, and the misleading common interpretations of Fourier analysis in hearing research.

Jai Ganesh · This is Cool

2476) The Alps

The Alps

Gist

The Alps are Europe's highest and most extensive mountain range, forming a crescent across eight countries (France, Switzerland, Italy, Austria, Germany, Slovenia, Liechtenstein, Monaco), famous for Mont Blanc, Matterhorn, stunning scenery, skiing, biodiversity, and unique climate zones, originating from tectonic plate collision and providing vital water sources for Europe.

Which countries are in the Alps?

They stretch across eight countries: France, Switzerland, Italy, Monaco, Liechtenstein, Austria, Germany and Slovenia. The mountains were formed millions of years ago as two giant tectonic plates collided, creating some of the highest mountains in Europe, like the Matterhorn, Mont Blanc, and the Eiger.

Summary

The Alps are some of the highest and most extensive mountain ranges in Europe, stretching approximately 1,200 km (750 mi) across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria, Slovenia, and Hungary.

The Alpine arch extends from Nice on the western Mediterranean to Trieste on the Adriatic and Vienna at the beginning of the Pannonian Basin. The mountains were formed over tens of millions of years as the African and Eurasian tectonic plates collided. Extreme shortening caused by the event resulted in marine sedimentary rocks rising by thrusting and folding into high mountain peaks such as Mont Blanc and the Matterhorn.

Mont Blanc spans the French–Italian border, and at 4,809 m (15,778 ft) is the highest mountain in the Alps. The Alpine region area contains 82 peaks higher than 4,000 m (13,000 ft).

The altitude and size of the range affect the climate in Europe; in the mountains, precipitation levels vary greatly and climatic conditions consist of distinct zones. Wildlife such as ibex live in the higher peaks to elevations of 3,400 m (11,155 ft), and plants such as edelweiss grow in rocky areas in lower elevations as well as in higher elevations.

Evidence of human habitation in the Alps goes back to the Palaeolithic era. A mummified man ("Ötzi"), determined to be 5,000 years old, was discovered on a glacier at the Austrian–Italian border in 1991.

By the 6th century BC, the Celtic La Tène culture was well established. Hannibal notably crossed the Alps with a herd of elephants, and the Romans had settlements in the region. In 1800, Napoleon crossed one of the mountain passes with an army of 40,000. The 18th and 19th centuries saw an influx of naturalists, writers, and artists, in particular, the Romanticists, followed by the Golden Age of Alpinism as mountaineers began to ascend the peaks of the Alps.

The Alpine region has a strong cultural identity. Traditional practices such as farming, cheese making, and woodworking still thrive in Alpine villages. However, the tourist industry began to grow early in the 20th century and expanded significantly after World War II, eventually becoming the dominant industry by the end of the century.

The Winter Olympic Games have been hosted in the Swiss, French, Italian, Austrian and German Alps. As of 2010, the region is home to 14 million people and has 120 million annual visitors.

Details

Alps, a small segment of a discontinuous mountain chain that stretches from the Atlas Mountains of North Africa across southern Europe and Asia to beyond the Himalayas. The Alps extend north from the subtropical Mediterranean coast near Nice, France, to Lake Geneva before trending east-northeast to Vienna (at the Vienna Woods). There they touch the Danube River and meld with the adjacent plain. The Alps form part of France, Italy, Switzerland, Germany, Austria, Slovenia, Croatia, Bosnia and Herzegovina, Montenegro, Serbia, and Albania. Only Switzerland and Austria can be considered true Alpine countries, however. Some 750 miles (1,200 kilometres) long and more than 125 miles wide at their broadest point between Garmisch-Partenkirchen, Germany, and Verona, Italy, the Alps cover more than 80,000 square miles (207,000 square kilometres). They are the most prominent of western Europe’s physiographic regions.

Though they are not as high and extensive as other mountain systems uplifted during the Paleogene and Neogene periods (i.e., about 65 million to 2.6 million years ago)—such as the Himalayas and the Andes and Rocky mountains—they are responsible for major geographic phenomena. The Alpine crests isolate one European region from another and are the source of many of Europe’s major rivers, such as the Rhône, Rhine, Po, and numerous tributaries of the Danube. Thus, waters from the Alps ultimately reach the North, Mediterranean, Adriatic, and Black seas. Because of their arclike shape, the Alps separate the marine west-coast climates of Europe from the Mediterranean areas of France, Italy, and the Balkan region. Moreover, they create their own unique climate based on both the local differences in elevation and relief and the location of the mountains in relation to the frontal systems that cross Europe from west to east. Apart from tropical conditions, most of the other climates found on the Earth may be identified somewhere in the Alps, and contrasts are sharp.

A distinctive Alpine pastoral economy that evolved through the centuries has been modified since the 19th century by industry based on indigenous raw materials, such as the industries in the Mur and Mürz valleys of southern Austria that used iron ore from deposits near Eisenerz. Hydroelectric power development at the end of the 19th and beginning of the 20th centuries, often involving many different watersheds, led to the establishment in the lower valleys of electricity-dependent industries, manufacturing such products as aluminum, chemicals, and specialty steels. Tourism, which began in the 19th century in a modest way, became, after World War II, a mass phenomenon. Thus, the Alps are a summer and winter playground for millions of European urban dwellers and annually attract tourists from around the world. Because of this enormous human impact on a fragile physical and ecological environment, the Alps are likely the most threatened mountain system in the world.

Physical features:

Geology

The Alps emerged during the Alpine orogeny, an event that began about 65 million years ago as the Mesozoic Era was drawing to a close. A broad outline helps to clarify the main episodes of a complicated process. At the end of the Paleozoic Era, about 250 million years ago, eroded Hercynian mountains, similar to the present Massif Central in France and Bohemian Massif embracing parts of Germany, Austria, Poland, and the Czech Republic, stood where the Alps are now located. A large landmass, formed of crystalline rocks and known as Tyrrhenia, occupied what is today the western Mediterranean basin, whereas much of the rest of Europe was inundated by a vast sea. During the Mesozoic (about 250 million to 65 million years ago) Tyrrhenia was slowly leveled by the forces of erosion. The eroded materials were carried southward by river action and deposited at the bottom of a vast ocean known as the Tethys Sea, where they were slowly transformed into horizontal layers of rock composed of limestone, clay, shale, and sandstone.

About 44 million years ago, relentless and powerful pressures from the south first formed the Pyrenees and then the Alps, as the deep layers of rock that had settled into the Tethys Sea were folded around and against the crystalline bedrock and raised with the bedrock to heights approaching the present-day Himalayas. These tectonic movements lasted until 9 million years ago. Tyrrhenia sank at the beginning of the Quaternary Period, about 2.6 million years ago, but remnants of its mass, such as the rugged Estéral region west of Cannes, are still found in the western Mediterranean. Throughout the Quaternary Period, erosive forces gnawed steadily at the enormous block of newly folded and upthrust mountains, forming the general outlines of the present-day landscape.

The landscape was further modeled during the Quaternary by Alpine glaciation and by expanding ice tongues, some reaching depths of nearly 1 mile (1.6 kilometres), that filled in the valleys and overflowed onto the plains. Amphitheatre-like cirques, arête ridges, and majestic peaks such as the Matterhorn and Grossglockner were shaped from the mountaintops; the valleys were widened and deepened into general U-shapes, and immense waterfalls, like the Staubbach and Trümmelbach falls in the Lauterbrunnen Valley of the Bernese Alps, poured forth from hanging valleys hundreds of feet above the main valley floors; elongated lakes of great depth such as Lake Annecy in France, Lake Constance, bordering Switzerland, Germany, and Austria, and the lakes of the Salzkammergut in Austria filled in many of the ice-scoured valleys; and enormous quantities of sands and gravels were deposited by the melting glaciers, and landslides—following the melting of much of the ice—filled in sections of the valley floors. The hills east of Sierre in the Rhône valley are an example of this last phenomenon, and they mark the French–German language divide in this area.

When the ice left the main valleys, there was renewed river downcutting, both in the lateral and transverse valleys. The river valleys have been eroded to relatively low elevations that are well below those of the surrounding mountains. Thus, Aosta, Italy, in the Pennine Alps, and Sierre, Switzerland, look up to peaks that tower a mile and a half above them. In the valley of the Arve River near Mont Blanc, the difference in relief is more than 13,100 feet.

Glaciation therefore modified what otherwise would have been a harsher physical environment: the climate was much milder in the valleys than on the surrounding heights, settlement could be established deeper into the mountains, communication was facilitated, and soils were inherently more fertile because of morainic deposits. Vigorous glacial erosion continues in modern times. Many hundreds of square miles of Alpine glaciers, such as those in the Ortles and Adamello ranges and such deep-valley glaciers as the Aletsch Glacier near Brig, Switzerland, are still found in the Alps. The summer runoff from these ice masses is instrumental in filling the deep reservoirs used to generate hydroelectricity.

Physiography

The Alps present a great variety of elevations and shapes, ranging from the folded sediments forming the low-lying pre-Alps that border the main range everywhere except in northwestern Italy to the crystalline massifs of the inner Alps that include the Belledonne and Mont Blanc in France, the Aare and Gotthard in Switzerland, and the Tauern in Austria. From the Mediterranean to Vienna, the Alps are divided into Western, Central, and Eastern segments, each of which consists of several distinct ranges.

The Western Alps trend north from the coast through southeastern France and northwestern Italy to Lake Geneva and the Rhône valley in Switzerland. Their forms include the low-lying arid limestones of the Maritime Alps near the Mediterranean, the deep cleft of the Verdon Canyon in France, the crystalline peaks of the Mercantour Massif, and the glacier-covered dome of Mont Blanc, which at 15,771 feet (4,807 metres) is the highest peak in the Alps. Rivers from these ranges flow west into the Rhône and east into the Po.

The Central Alps occupy an area from the Great St. Bernard Pass east of Mont Blanc on the Swiss-Italian border to the region of the Splügen Pass north of Lake Como. Within this territory are such distinctive peaks as the Dufourspitze, Weisshorn, Matterhorn, and Finsteraarhorn, all 14,000 feet high. In addition, the great glacial lakes—Como and Maggiore in the south, part of the drainage system of the Po; and Thun, Brienz, and Lucerne (Vierwaldstättersee) in the north—fall within this zone.

The Eastern Alps, consisting in part of the Rätische range in Switzerland, the Dolomite Alps in Italy, the Bavarian Alps of southern Germany and western Austria, the Tauern Mountains in Austria, the Julian Alps in northeastern Italy and northern Slovenia, and the Dinaric Alps along the western edge of the Balkan Peninsula, generally have a northerly and southeasterly drainage pattern. The Inn, Lech, and Isar rivers in Germany and the Salzach and Enns in Austria flow into the Danube north of the Alps, while the Mur and Drau (Austria) and Sava (Balkan region) rivers discharge into the Danube east and southeast of the Alps. Within the Eastern Alps in Italy, Lake Garda drains into the Po, whereas the Adige, Piave, Tagliamento, and Isonzo pour into the Gulf of Venice.

Differences in relief within the Alps are considerable. The highest mountains, composed of autochthonous crystalline rocks, are found in the west in the Mont Blanc massif and also in the massif centring on Finsteraarhorn (14,022 feet) that divides the cantons of Valais and Bern. Other high chains include the crystalline rocks of the Mount Blanche nappe—which includes the Weisshorn (14,780 feet)—and the nappe of Monte Rosa Massif, sections of which mark the frontier between Switzerland and Italy. Farther to the east, Bernina Peak is the last of the giants over 13,120 feet (4,000 metres). In Austria the highest peak, the Grossglockner, reaches only 12,460 feet; Germany’s highest point, the Zugspitze in the Bavarian Alps, only 9,718 feet; and the highest point of Slovenia and the Julian Alps, Triglav, only 9,396 feet. Some of the lowest areas within the Western Alps are found at the delta of the Rhône River where the river enters Lake Geneva, 1,220 feet. In the valleys of the Eastern Alps north of Venice, elevations of only about 300 feet are common.

Climate of the Alps

The location of the Alps, as well as the great variations in their elevations and exposure, give rise to extreme differences in climate, not only among separate ranges but also within a particular range itself. Because of their central location in Europe, the Alps are affected by four main climatic influences: from the west flows the relatively mild, moist air of the Atlantic; cool or cold polar air descends from northern Europe; continental air masses, cold and dry in winter and hot in summer, dominate in the east; and, to the south, warm Mediterranean air flows northward. Daily weather is influenced by the location and passage of cyclonic storms and the direction of the accompanying winds as they pass over the mountains.

Temperature extremes and annual precipitation are related to the physiography of the Alps. The valley bottoms clearly stand out because generally they are warmer and drier than the surrounding heights. In winter nearly all precipitation above 5,000 feet is in the form of snow, and depths from 10 to 33 feet or more are common. Snow cover lasts from approximately mid-November to the end of May at the 6,600-foot level, blocking the high mountain passes; nevertheless, relatively snowless winters can occur. Mean January temperatures on the valley floors range from 23 to 39 °F (−5 to 4 °C) to as high as 46 °F (8 °C) in the mountains bordering the Mediterranean, whereas mean July temperatures range between 59 and 75 °F (15 and 24 °C). Temperature inversions are frequent, especially during autumn and winter, and the valleys often fill with fog and stagnant air for days at a time. At those times the levels above 3,300 feet can be warmer and sunnier than the low-lying valley bottoms. Winds can play a prominent role in daily weather and microclimatic conditions.

A foehn wind can last from two to three days and blows either south–north or north–south, depending on the tracking of cyclonic storms. The air mass of such a wind is cooled adiabatically as it passes upward to the mountain crests, which precipitates either rain or snow and retards the rate of cooling. When this drier air descends on the lee side, it is adiabatically warmed by compression at a constant rate and therefore has a higher temperature at the same altitude than when it began its upward flow. Snow in the affected areas disappears rapidly.

Avalanches, one of the great destructive forces of nature, are an ever-present danger during the period from late November to early June. Most follow well-defined paths, but much of the fear of avalanches is related to the difficulty of predicting where and when they will strike. Avalanches are a greater threat to human life and property in the Alps than in other mountain ranges because of the region’s relatively high population density and the tens of millions of tourists who visit each year. The development of ski resorts also has depleted many forests, which serve as natural barriers against avalanches.

Additional Information:

Geography:

The Alps are the highest and most extensive mountain range system that lie in south-central Europe. The mountain range stretches approximately 750 miles (1,200 kilometers) in a crescent shape across eight Alpine countries: France, Switzerland, Monaco, Italy, Liechtenstein, Austria, Germany, and Slovenia.

Ecology:

The Alps are an interzonal mountain system (Orobiome), or a “transition area” between Central and Mediterranean Europe. The Alps have high habitat diversity, with 200 habitats classified throughout the mountain range. This mountain range is home to a high level of biodiversity.

According to the World Wildlife Fund (WWF), there are over 4,500 species of plants, 200 bird species, 21 amphibian species, 15 reptile species, and 80 mammal species. Many of these species have made adaptations to the harsh cold conditions and high altitudes.

None of the 80 mammal species found in the Alps are “strictly” endemic, meaning they occur in the Alps and nowhere else in the world. Some of the larger carnivore species found in the Alps include the Eurasian lynx, the wolf, and the brown bear, and herbivores include the Alpine ibex, the chamois. These populations have been reduced in size or fragmented into small groups. There are also numerous rodent species found in the Alps, such as voles and marmots.

There are about 200 breeding bird species, as well as an equal number of migratory species, in the Alps. The largest bird species found in the Alps are the golden eagle and the bearded vulture. The alpine chough is the most common bird found in the region.

Of the 21 total species of amphibians, only one is endemic, Salamandra lanzai. There are fifteen reptile species present, including adders and vipers.

According to WWF, the Alps are one of the regions with the richest flora and fauna in Europe, second only to the Mediterranean. There are about 4,500 species of vascular plants, 800 species of mosses, 300 liverworts, 2500 lichens and more than 5000 fungi found in the Alps. About 8 percent of the vascular species are endemic. The variety of habitats in the Alps helps to promote the uniqueness of Alpine flora, along with the harsh environmental conditions that drive species to change and adapt.

Highest peak:

Mont Blanc is the highest peak at 15,776 feet (4,808 m). It is the second-highest and second most prominent mountain in Europe and the eleventh most prominent mountain summit in the world. The Mont Blanc massif spans across France, Italy, and Switzerland, while the summit itself lies on the border between France and Italy. There are about a hundred peaks higher than 13,000 ft (4,000 m) in the Alpine region.

Rivers:

The Alps provide lowland Europe with drinking water, irrigation, and hydroelectric power. Although the area is only about 11% of the surface area of Europe, the Alps provide up to 90% of water to lowland Europe. Major European rivers flow from the Alps, including the Rhine, the Rhône, the Inn, and the Po.

Glaciers:

The major glacierized areas in the Alps are situated along the crest of the mountain chain, with the largest glaciers often found at the highest elevations. There are smaller glaciers scattered throughout the Alps.

The Swiss Alps is known for glaciers, containing around 1,800 glaciers. The region’s glaciers include the longest glacier in the Alps: the Aletsch Glacier.

Additional Facts:

* At over 12 miles long and about a half-mile thick, the famous Aletsch valley glacier is the longest in the Alps, but due to climate change, the Aletsch is shrinking and predicted to completely melt by the end of this century.
* The Alps are Europe’s highest and most extensive mountain range.
* Mont Blanc is the highest mountain in the Alps, spanning 3 countries. Its granite ramparts distinguish it from other peaks. Mont Blanc’s ranges rose straight from the deep and are still rising, a phenomenon caused by glacial movement.
* The limestone Dolomites in Italy are half as high as Mont Blanc and were created as Africa’s collision with Europe pushed together an ancient tropical seafloor with the ancient skeletons of marine organisms into the sky.
* Humans have been living in the Alps since Paleolithic times, about 60,000 to 50,000 years ago. The Alpine region continues to have a strong cultural identity and its traditional culture of farming, cheesemaking, and woodworking still exists in Alpine villages. However, the tourism industry has been growing since the 20th century. While the region is home to 14 million people, it has 120 million annual visitors.

Jai Ganesh · Dark Discussions at Cafe Infinity

Colleges Quotes - II

1. So far as the colleges go, the sideshows are swallowing up the circus. - Woodrow Wilson

2. I came from a Hindi medium school... the principal felt that I would not fit into an English medium college. Though I was top in my class in school, and I got admission in other colleges, but I really wanted to study in St. Xavier's. - Lakshmi Mittal

3. The public/private partnerships are taking various forms in India. It is individuals who are socially oriented are setting up schools. They're setting up colleges. They're setting up universities. They're setting up primary-education schools in the villages, particularly the villages their original families came from. - Azim Premji

4. I think Facebook is an online directory for colleges... If I want to get information about you, I just go to TheFacebook, type in your name, and it hopefully pulls up all the information I'd care to know about you. - Mark Zuckerberg

5. Colleges produce more sports therapists than engineers. Perhaps because America is a sporty country: a lot of outdoors. - Azim Premji.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#10711. What does the term in Geography Corrasion mean?

#10712. What does the term in Geography Coulee mean?

Jai Ganesh · Jai Ganesh's Puzzles

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#5907. What does the noun gratuity mean?

#5908. What does the noun gravel mean?

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#2550. What does the medical term Medulloblastoma mean?

Jai Ganesh · Jokes

Q: Which basketball players eat fruits?
A: The ones who like to cherry pick.
* * *
Q: Did you hear the joke about the cherry?
A: It was pit-iful.
* * *
Q: What do you call cherries playing the guitar?
A jam session.
* * *
Q: What did one cherry say to the other cherry?
A: If you weren't so sweet, we wouldn't be in this jam!
* * *
Q: Did you hear about the fruit that gave people a warm fuzzy feeling all over?
A: She was the cherry on top.
* * *

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9834.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6328.

Jai Ganesh · Exercises

Hi,

2685.

Jai Ganesh · Science HQ

Heart Valve Surgery

Gist

How is heart valve surgery done?

The surgeon makes a long cut down the centre of your chest, through your breastbone. Your heart is connected to a machine to keep blood flowing around your body during the operation (heart-lung bypass machine). The surgeon cuts into your heart to reach the damaged valve.

Can you walk after heart valve surgery?

People are usually practicing very basic self-care and are encouraged to get up, to breathe deeply and to resume eating, drinking and walking as soon as possible after surgery.

Summary:

What is heart valve surgery?

Heart valve surgery and procedures are performed to repair or replace a valve in the heart that is not working properly because of valvular heart disease (also called heart valve disease). Heart valve surgery is open-heart surgery through the breastbone, into the chest. It is a major operation that can last two hours or longer and recovery often takes several weeks. There are newer, less invasive procedures suitable for some types of valvular heart disease, but they are only done at certain hospitals.

Why is it done?

In a healthy heart, valves control the flow of blood by making it move in one direction through the heart and the body. If a valve is not working correctly, blood flow and the delicate network of blood vessels that carry oxygen throughout the body are affected.

If your valve problem is minor, your doctor may monitor your symptoms or treat you with medication. If your condition is more serious, surgery is usually required to repair or replace the valve to prevent any lasting damage to your heart valve and your heart.

Heart valve surgery and procedures are performed to repair or replace a valve in the heart that is not working properly because of valvular heart disease (also called heart valve disease). Heart valve replacement surgery is open-heart surgery through the breastbone, into the chest. It is a major operation that can last two hours or longer and recovery often takes several weeks. There are newer, less invasive procedures suitable for some types of valvular heart diseases.

In a healthy heart, valves control the flow of blood by making it move in one direction through the heart and the body. The valve can either become stenotic, which means it is narrowed and thus does not allow the blood to flow smoothly from one chamber to another or it starts leaking which hampers the forward flow of blood.

If your valve problem is minor, your doctor may monitor your symptoms or treat you with medication. If your condition is more serious, surgery is usually required to repair or replace the valve to prevent any lasting damage to your heart valve and your heart.

What is Done?

Depending on the problem, there are several different procedures for repairing or replacing valves.

1. Surgical Valve Repair

Surgical procedures are generally used for problems with the mitral or tricuspid valves.

2. Commissurotomy

It is a treatment for a tight valve. The valve flaps (leaflets) are cut to loosen the valve slightly, allowing blood to pass easily.

3. Annuloplasty

It is done for a leaky valve. There is a ring of fibrous tissue at the base of the heart valve called the annulus. To repair an enlarged annulus, sutures are sewn around the ring to make the opening smaller. Or, a ring-like device is attached around the outside of the valve opening to support the valve so it can close more tightly.

4. Valvulotomy

It is a procedure to enlarge narrowed heart valves. It can also be done with the help of a balloon.

5. Non-Surgical Valve Repair

Percutaneous or catheter-based procedures are done without any incisions in the chest or stopping the heart. Instead, a thin flexible tube called a catheter is inserted into a blood vessel in your groin or arm and then threaded through the blood vessels into your heart. Percutaneous or balloon valvuloplasty/valvotomy is used for stiffened or narrowed (stenosed) pulmonary, mitral, or aortic valves. A balloon tip on the end of the catheter is positioned in the narrowed valve and inflated to enlarge the opening. Percutaneous mitral valve repair methods – such as edge-to-edge repair – can fix a leaky mitral valve in a patient who is considered at high risk for surgery. A catheter holding a clip is inserted into the groin and up into the left side of the heart. The open clip is positioned beyond the leaky valve and then pulled back so it catches the flaps (leaflets) of the mitral valve. Once closed, the clip holds the leaflets together and stops the valve from leaking.

Details

Heart valve surgery repairs or replaces a valve that’s too narrow or doesn’t close right. Valves need to work efficiently to help blood flow the right direction through your heart. Heart valve surgery options include open, minimally invasive or through vein access to your heart. It takes one or two months to recover, depending on the surgery.

Overview:

What is heart valve surgery?

Heart valve surgery is an operation that fixes or replaces one or more of the four valves in your heart. Your valves, located between your heart’s four chambers, keep your blood moving the right way. Valves act like doors that open and close with each heartbeat, letting blood flow in and out of the chambers. When valves are working right, your blood should flow through your heart in one direction each time your heart beats.

Your four heart valves are:

* Tricuspid, between your right upper and lower chambers.
* Pulmonary, between your right ventricle (lower chamber) and your pulmonary artery.
* Mitral, between your left upper and lower chambers.
* Aortic, between your left ventricle (lower chamber) and your aorta.

Some of the blood may go back to the chamber or room it just left. Other times, a valve may become narrow, which may prevent blood from moving forward. This is a problem because it keeps your heart from working efficiently. Although heart valve surgery may make you feel fearful, it helps your heart work better. And if your heart’s working better, you’ll feel better, too.

Types of heart valve surgery

The type of heart valve surgery you have will depend on several factors. Your provider will consider:

* Your heart’s structure.
* Your age.
* Other medical conditions you may have.
* Your lifestyle.

Tests will tell your healthcare provider the location, type and extent of your valve disease. Your heart valve issue may have started at birth, or you may have developed a leak, stiffness or narrowing in your valve. The test results help determine the best type of procedure for you.

Your cardiac surgeon can combine valve surgery with other heart surgeries. Examples include surgeries that involve more than one valve procedure and combining heart valve surgery with:

* Bypass surgery.
* Aortic aneurysm surgery.
* Surgery to treat atrial fibrillation.

Heart valve repair surgery

A repair surgery fixes the damaged or faulty valve while preserving much of your own tissue. Surgeons repair mitral valves more than the other valves, but repair surgery can also treat problems with the aortic and tricuspid valves.

Heart valve replacement surgery

Heart valve replacement surgery removes the faulty valve and replaces it with a biological (pig, cow or human tissue) or mechanical (metal or carbon) valve. All valve replacements are biocompatible. That means your immune system won’t reject your new valve. Replacement options include the Ross procedure and minimally invasive procedures like TAVR.

Can a heart valve repair itself?

No, a heart valve can’t repair itself. Valve disease doesn’t go away. It gets worse with time. As the disease gets worse, you’ll have more symptoms and your overall health will suffer. These changes often happen slowly, but they can also occur very quickly.

Depending on the type and extent of valve disease you have, medication may help with symptoms for the short term. Surgery is the only effective long-term solution. Your healthcare provider will help determine when it’s time for surgery.

When is heart valve surgery necessary?

You’ll most likely need heart valve surgery if medicine doesn’t help anymore for symptoms like:

* Chest pain.
* Difficulty breathing.
* Fainting.

Treatment Details:

How should I prepare for heart valve surgery?

You may have tests the day before your surgery. These may include:

* Chest X-ray.
* Echocardiogram.
* Electrocardiogram (EKG).
* CT (computed tomography) scan.
* Cardiac catheterization.
* Blood tests.

Check with your healthcare provider about which medications you can take before surgery. Don’t eat or drink anything after midnight the day of your surgery.

On the day of your procedure, wear loose, comfortable clothes and shoes that are easy to put on. If you wear a bra, you may want to bring one that’s easy to put on without raising your arms. The person who brings you to the hospital can hold on to these items for you during surgery.

Before your surgery, a healthcare provider will shave and clean the area where your surgeon will be working.

What happens during valve surgery on your heart?

During heart valve surgery, a provider will:

* Give you medicine through an IV in your arm or hand so you can sleep deeply and painlessly.
* Use the smallest incision they can for your surgery.
* Set up a machine to take over for your heart and lungs during surgery.
* Repair or replace your heart valve.
* Restart your heart.
* Close your chest.

Heart valve surgery options include:

* Traditional or open-heart surgery: An incision (6 to 8 inches) through your breastbone.
* Minimally invasive heart valve surgery: A smaller incision (3 to 4 inches or smaller). Techniques include endoscopic or keyhole approaches (also called port access, thoracoscopic or video-assisted surgery) and robotic-assisted surgery.
* Transcatheter: Your provider will put a catheter into a larger artery, like your femoral artery in your groin, and do the work without cutting your chest.

How long does this procedure take?

Open-heart surgery for a heart valve replacement can take two to five hours. Repairs or minimally invasive procedures may take less time.

What happens after heart valve surgery?

After surgery, your healthcare team may move you to an intensive care unit (ICU) where they can monitor you closely. After that, you’ll be in a regular room. You may be in the hospital for five to seven days.

Machines connected to you will monitor your blood pressure and heart rate. You may have tubes coming out of your chest to drain fluids.

Your provider will encourage you to eat, drink and walk as soon as you can after surgery. You can start with short walks around your room or down the hall and increase your distance little by little.

Your provider may sign you up for cardiac rehab, a carefully monitored exercise program.

Risks / Benefits:

What are the benefits of heart valve surgery?

Heart valve surgery can ease your symptoms, improve your life expectancy and help prevent death.

The potential advantages of heart valve repair vs. heart valve replacement surgery are:

* Lower risk of infection.
* Less need for lifelong anticoagulant (blood thinning) medication.
* Valve surgeries, including heart valve repair and replacement, are the most common minimally invasive procedure.

The benefits of minimally invasive surgery include:

* Lower chance of infection.
* Less bleeding and trauma.
* Shorter hospital stay.
* Shorter recovery.
* Improved cosmesis (appearance) and smaller wounds.

What are the risks or complications of heart valve surgery?

Any surgery involves risks. Heart valve surgery risks may include:

* Heart attack.
* Heart failure.
* Abnormal heart rhythm — you may need a pacemaker.
* Stroke.
* Blood clots.
* Infection.
* Bleeding.

Risks are related to your age, other medical conditions you may have and how many procedures you have in a single operation. Your cardiologist and surgeon will talk to you about these risks before your surgery.

If you’ve had a valve fixed or replaced, you may be at a higher risk of getting infective endocarditis. But this can also happen with an unrepaired faulty valve. In certain cases, your healthcare provider may prescribe antibiotics to keep you from getting endocarditis from some types of dental work. You can reduce the risk of endocarditis yourself by taking good care of your teeth.

Recovery and Outlook:

How long is recovery after heart valve surgery?

Heart valve surgery recovery takes about four to eight weeks. But your recovery time may be shorter if you had minimally invasive surgery or surgery through a vein.

The way you feel after surgery depends on:

* Which valve was repaired or replaced.
* Your overall health before the surgery.
* Which method your provider used to get to your heart (large incision, small incision or through a vein).
* How the surgery went.
* How well you take care of yourself after surgery.

Caring for yourself after surgery

Recovery after heart valve surgery takes time. Be kind to yourself. Here are some tips:

* Go to your follow-up appointments during recovery so your provider can monitor your progress.
* Don’t take on more than you can handle. You can expect to tire easily for the first three weeks after surgery.
* Don’t drive for a few weeks after surgery.
* Don’t handle anything that weighs more than 15 pounds for the first six to eight weeks after surgery.
* Talk to your provider about when you can go back to work. It’s usually six to 12 weeks after surgery.

What is the survival rate following heart valve surgery?

A study found that people who were more physically active in the year after surgery had a lower risk of death than those who didn’t exercise much. The death rate ranges from 0.1% to 10% depending on the operation and a person's overall health.

When To Call the Doctor:

When should I call my healthcare provider?

Contact your provider if:

* You have chest pain or pain near your incision.
* You feel depressed. This can happen after surgery and can make your recovery take longer.
* You have a fever, which can be a sign of infection.
* You gain more than 5 pounds, which may mean you’re retaining fluid.

Additional Information:

Overview

Heart valve surgery is a procedure to treat heart valve disease. Heart valve disease happens when at least one of the four heart valves is not working properly. Heart valves keep blood flowing in the correct direction through the heart.

The four heart valves are the mitral valve, the tricuspid valve, the pulmonary valve and the aortic valve. Each valve has flaps — called leaflets for the mitral and tricuspid valves and cusps for the aortic and pulmonary valves. These flaps should open and close once during each heartbeat. Valves that don't open and close properly change blood flow through the heart to the body.

In heart valve surgery, a surgeon repairs or replaces the damaged or diseased heart valve or valves. Methods to do this may include open-heart surgery or minimally invasive heart surgery.

The type of heart valve surgery needed depends on age, overall health, and the type and severity of heart valve disease.

Types

* Annuloplasty
* Valvuloplasty

Why it's done

Heart valve surgery is done to treat heart valve disease. There are two basic types of heart valve disease:

* A narrowing of a valve, called stenosis.
* A leak in a valve that allows blood to flow backward, called regurgitation.

You might need heart valve surgery if you have heart valve disease that affects your heart's ability to pump blood.

If you don't have symptoms or if your condition is mild, your healthcare team might suggest regular health checkups. Lifestyle changes and medicines might help manage symptoms.

Sometimes, heart valve surgery may be done even if you don't have symptoms. For example, if you need heart surgery for another condition, surgeons might repair or replace a heart valve at the same time.

Ask your healthcare team whether heart valve surgery is right for you. Ask if minimally invasive heart surgery is an option. It does less damage to the body than does open-heart surgery. If you need heart valve surgery, choose a medical center that has done many heart valve surgeries that include both repair and replacement of the valve.

Risks

Heart valve surgery risks include:

* Bleeding.
* Infection.
* Irregular heart rhythm, called arrhythmia.
* Problem with a replacement valve.
* Heart attack.
* Stroke.
* Death.

How you prepare

Your surgeon and treatment team discuss your heart valve surgery with you and answer any questions. Before you go to the hospital for heart valve surgery, talk with your family or loved ones about your hospital stay. Also discuss what help you'll need when you come home.

Food and medicines

Before you have heart valve surgery, talk to your care team about:

* Any medicines you regularly take and whether you can take them before your surgery.
* Allergies or reactions you've had to medicines.
* When you should stop eating or drinking the night before or the morning of the surgery.

Clothing and personal items

If you're having heart valve surgery, your treatment team might suggest that you bring certain items to the hospital, including:

* A list of your medicines.
* Eyeglasses, hearing aids or dentures.
* Personal care items, such as a brush, a comb, a shaving kit and a toothbrush.
* Loose, comfortable clothing.
* A copy of your advance directive. This is a legal document. It includes instructions about the kinds of treatments you want — or don't want — in case you become unable to express your wishes.
* Items that help you relax, such as portable music players or books.

During heart valve surgery, do not wear:

* Contact lenses.
* Dentures.
* Eyeglasses.
* Jewelry.
* Nail polish.

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#2 This is Cool » Monaco » Yesterday 20:35:29

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