Posts by Jai Ganesh

Jai Ganesh · This is Cool

Linear Accelerator

Gist

A linear accelerator (LINAC) is a device that uses high-frequency electromagnetic waves to accelerate charged particles—primarily electrons—to near the speed of light in a straight line, commonly used for cancer radiotherapy. It generates high-energy X-rays or electron beams that precisely target and destroy tumors, minimizing damage to surrounding healthy tissue.

A medical linear accelerator (LINAC) is the device most commonly used for external beam radiation treatments for patients with cancer. It delivers high-energy x-rays or electrons to the region of the patient's tumor.

Summary

A linear particle accelerator (often shortened to linac) is a type of particle accelerator that accelerates charged subatomic particles or ions to a high speed by subjecting them to a series of oscillating electric potentials along a linear beamline. The principles for such machines were proposed by Gustav Ising in 1924, while the first machine that worked was constructed by Rolf Widerøe in 1928 at the RWTH Aachen University. Linacs have many applications: they generate X-rays and high energy electrons for medicinal purposes in radiation therapy, serve as particle injectors for higher-energy accelerators, and are used directly to achieve the highest kinetic energy for light particles (electrons and positrons) for particle physics.

The design of a linac depends on the type of particle that is being accelerated: electrons, protons or ions. Linacs range in size from a cathode-ray tube (which is a type of linac) to the 3.2-kilometre-long (2.0 mi) linac at the SLAC National Accelerator Laboratory in Menlo Park, California.

Details

Linear accelerators, commonly referred to as linacs, are devices designed to accelerate charged particles along a straight path using radio frequency electromagnetic fields. Unlike electrostatic accelerators, which utilize static electric fields, linacs achieve acceleration through specific designs tailored for different particle types, such as electrons, protons, or heavy ions. The two primary designs of linacs are drift-tube and waveguide systems. In a drift-tube linac, charged particles drift through a series of hollow metal tubes, gaining energy at gaps as the voltage alternates to ensure they are continually accelerated.

Waveguide linacs operate by allowing microwaves to guide particles through a hollow pipe, synchronizing the phase velocity of the waves with the particles' speed to maintain energy gain. Linacs are widely used in research, particularly in nuclear physics, where they serve as sources for particle beams. They also have significant applications in medical fields, particularly for radiation therapy and sterilization of medical instruments, as well as in various industrial processes like food preservation and materials testing. The evolution of linacs from initial concepts in the early 20th century to their modern forms has led to advancements in particle energy and beam intensity, making them invaluable tools in both scientific research and industry.

Linear accelerators are devices that augment the energy of a beam of charged particles. Acceleration occurs in a straight line, using radio frequency electromagnetic fields.

Overview

As the name implies, a linear accelerator (linac) is a device in which charged particles travel in a straight line as they are being accelerated. The term also implies in practice that the acceleration is accomplished by means of radio frequency electromagnetic fields and not by means of electrostatic fields as in an electrostatic accelerator. Details of the design of linacs depend on whether they are intended for accelerating electrons, protons, or heavy ions.

Linacs have two basic design types: the drift-tube design and the waveguide design. A drift tube is a hollow metal cylinder, open at both ends; the particles travel along the axis of the cylinder. While they are inside the cylinder and far from either end, the particles do not experience any appreciable force because the electric and magnetic fields are shielded out by the metal of the cylinder. Since the particles experience no force in this region, they are drifting. The essence of the drift-tube method is that a large number of drift tubes are placed one after the other with short gaps between two consecutive tubes. Each tube is arranged to have either a positive or a negative voltage, with the sign alternating from one tube to the next. When particles arrive at the gap between two successive cylinders, the voltages must be arranged so that the particles are repelled from the cylinder they are leaving and attracted to the cylinder they are approaching. When they cross the gap, the particles gain a certain amount of energy. If nothing more were done, they would lose that energy at the next gap, where the force would be in the opposite direction, and the particles would be decelerated. To prevent this loss, the polarities of all the cylinders are reversed when the particles are near the center of the drift tubes. Thus, at every gap the polarity has been arranged for the particles to gain energy. The oscillation in the polarity of the drift tubes takes place at a radio frequency that is characteristic of microwaves.

The particles do not gain much energy at each gap. Nevertheless, the number of tubes (and therefore the number of gaps) can be made quite large, leading to a high value of the beam energy without the need for especially high voltage. In the upstream end of the accelerator, the particles are moving more slowly than they are at the downstream end after they have been accelerated; therefore, the length of the drift tubes must increase gradually from upstream to downstream, more or less proportional to the square root of the tube number. Each gap supplies the same energy increment, and the velocity varies as the square root of the kinetic energy, for nonrelativistic motion.

The drift tubes are all contained inside a long cylindrical tank that is maintained at a good vacuum so that the beam particles are not lost to collisions with air molecules. Devices called klystrons generate the microwaves outside the tank and conduct them to the inside, where they cause electric and magnetic fields primarily at the gaps between drift tubes, secondarily in the region between the drift tubes and the inside wall of the tank, but essentially not deep in the interior of the drift tubes.

Initially, it may seem logical to run the accelerator so that the particles arrive at the gap when the voltage is at its peak, thereby maximizing the energy imparted to the particles in the beam. If this setup is adopted, however, the beam intensity will suffer, since the particles do not all reach the gap in time to take advantage of the full voltage. As a result, the latecomers will get less than the proper gain in energy, causing them to arrive even later at the next gap. Soon, they will be lost to the beam. It is more efficient--and even essential--to design the system with enough extra voltage so that the particles arrive at the gap before the maximum voltage is reached: The particles that arrive early (the ones with too much energy) will receive less than the nominal amount of force at the gap, and their energy will be closer to the right amount. The latecomers (the ones with too little energy) will get to the gap when the voltage is higher than nominal, so they will pick up enough extra energy to get them to the next gap a little earlier. As a result, far fewer particles will be lost to the beam. This is known as the principle of phase stability.

As the particles cross the gaps, the electric forces acting on them tend not only to accelerate them but also to deflect them away from the axis of the system. The latter effect "defocuses" the beam. There are several possible remedies: One can place a small screen across the end of the drift tube to redirect the electric fields; one can use small, specially shaped pieces of metal that accomplish the same purpose as the screen but allow more particles to pass through; or one can use quadruple magnets to impose external focusing on the beam.

A waveguide linac essentially is a hollow pipe with microwaves flowing through it, with the magnetic fields perpendicular to the axis of the pipe and the electric fields at least partially parallel to the axis to impart acceleration to the charged particles in the beam. For all smooth hollow pipes, however, the phase velocity of microwaves is greater than the speed of light, and the special theory of relativity states that no particle can go faster than the speed of light (c). The particles cannot keep up with the accelerating wave. The solution to this problem is to place metal circles at regular intervals along the inside of the pipe. Each circle has a hole in its center large enough to accommodate the passage of the beam. The resulting structure is called an "iris-loaded waveguide." A wave traveling in a periodic structure can be arranged to have any phase velocity one chooses: greater than c, less than c, zero, or even negative. For linacs, the phase velocity of the microwaves is matched to the velocity of the particles being accelerated. Thus, the particles ride the wave exactly as a surfer rides a water wave in the ocean, picking up energy as the wave progresses. If the particles are slightly ahead of the region of maximum field strength, they will also have phase stability.

An alternate way to understand the working of a waveguide linac is to consider it as a large number of cavity oscillators that are connected loosely to one another by the holes where the beam goes. In each cavity there is a standing wave, with the electric field somewhere along the axis so as to provide acceleration. The timing or phase of the oscillations shifts from one cavity to the next so that it is synchronized for the arrival of the particles.

The spacing of the irises (or, alternately, the cavity sizes) varies more for proton or heavy ion linacs than for electron linacs. For the latter, a small energy gain brings the particles' velocity very close to c, and thereafter, they gain energy in regular amounts, with minimal change in the velocity. In a high-energy electron linac, the energy can be varied simply by changing the number of klystrons that drive the accelerator, since the energy is proportional to the square root of the number of klystrons.

Applications

Linacs are used as sources of particles for research in nuclear physics at low, medium, and high energies. The most spectacular example is the 3-kilometer linac at the Stanford Linear Accelerator Center (SLAC) in California. This machine is an electron linac of the waveguide type. It can also accelerate positrons on the opposite half of the cycle, the half that is useless for electrons. The positrons are made inside the accelerator itself by making some of the accelerated electrons impinge on a target located about a third of the way from the start.

At Los Alamos in New Mexico there is a large proton linac that is used for research in medium-energy nuclear physics. This accelerator is best considered as a sequence of cavity oscillators, where alternate cavities do not contribute to the energy gain, but are necessary to maintain accurate timing. These extra cavities are moved out of the beam line so as to shorten the total length of the accelerator.

Linacs are used not only as stand-alone accelerators but also as preaccelerators for other types of accelerators, such as synchrotrons. Proton synchrotrons work better if the protons are relativistic at the outset. The standard procedure is to use a linac that accepts protons at a modest energy and accelerates them to such a high energy that the synchrotron can handle them more effectively. The large accelerator at the Fermi National Accelerator at Batavia, Illinois, is a proton synchrotron built in the form of a ring that is 1 kilometer in radius. The main ring cannot operate effectively with protons direct from the ion source. Instead, the protons from the ion source are accelerated by an electrostatic accelerator of the math-Walton type and then injected into a proton linac, which accelerates them to an energy such that they can be sent to a small synchrotron, after which they go into the main ring. The linac is one indispensable link in a chain of accelerators.

Linacs are also used in pure research as a postaccelerator to an electrostatic accelerator.

Linacs have been built for this purpose with superconducting resonant cavities, using either niobium-copper or lead-plated copper for the walls of the resonator.

The high beam intensity of linear accelerators has made them valuable for medical use, both in radiation therapy and in sterilization of numerous types of small objects used in medicine. For example, surgical thread has to be free of microbes that could cause disease in a patient who has undergone surgery. Radiation from an electron linac can be an effective replacement for either heat or chemicals, the two older methods of sterilization.

The sterilizing properties of radiation have led to varied industrial applications of linacs. They can be used to treat waste water to kill harmful organisms. They can also be used for preservation of food. For example, even a small dose of radiation will prevent the sprouting of onions, garlic, or potatoes at a cost far less than that of the energy needed to refrigerate these food items. At higher levels, the radiation can destroy insects, fungi, or microbes that cause wastage of food.

Other industrial applications exist that do not involve sterilization, such as using radiation to study wear on the surface of metal parts. Many examples of this type of application come from parts of automobile engines: piston rings, cylinder walls, and cams are all metal parts that experience wear from rubbing, in spite of lubrication with oil. It is important to know how the wear takes place and how fast. A linac can provide the radiation needed to perform such studies.

Another class of examples involves irradiation of plastics to induce polymerization and cross-linkage. For example, a plastic object may be formed by pressing the plastic into the required shape. The plastic may "remember" its original form, however, and revert to that rather than keep its new shape. If the plastic is irradiated by the beam from a linac not long after it is pressed, the structure of the polymer tends to be modified so that the plastic "forgets" its original shape.

Additional Information

A linear accelerator is a type of particle accelerator (q.v.) that imparts a series of relatively small increases in energy to subatomic particles as they pass through a sequence of alternating electric fields set up in a linear structure. The small accelerations add together to give the particles a greater energy than could be achieved by the voltage used in one section alone.

In 1924 Gustaf Ising, a Swedish physicist, proposed accelerating particles using alternating electric fields, with “drift tubes” positioned at appropriate intervals to shield the particles during the half-cycle when the field is in the wrong direction for acceleration. Four years later, the Norwegian engineer Rolf Wideröe built the first machine of this kind, successfully accelerating potassium ions to an energy of 50,000 electron volts (50 kiloelectron volts).

Linear machines for accelerating lighter particles, such as protons and electrons, awaited the advent of powerful radio-frequency oscillators, which were developed for radar during World War II. Proton linacs typically operate at frequencies of about 200 megahertz (MHz), while the accelerating force in electron linacs is provided by an electromagnetic field with a microwave frequency of about 3,000 MHz.

The proton linac, designed by the American physicist Luis Alvarez in 1946, is a more efficient variant of Wideröe’s structure. In this accelerator, electric fields are set up as standing waves within a cylindrical metal “resonant cavity,” with drift tubes suspended along the central axis. The largest proton linac is at the Clinton P. Anderson Meson Physics Facility in Los Alamos, N.M., U.S.; it is 875 m (2,870 feet) long and accelerates protons to 800 million electron volts (800 megaelectron volts). For much of its length, this machine utilizes a structural variation, known as the side-coupled cavity accelerator, in which acceleration occurs in on-axis cells that are coupled together by cavities mounted to their sides. These coupling cavities serve to stabilize the performance of the accelerator against changes in the resonant frequencies of the accelerating cells.

Electron linacs utilize traveling waves rather than standing waves. Because of their small mass, electrons travel at close to the speed of light at energies as low as 5 megaelectron volts. They can therefore travel along the linac with the accelerating wave, in effect riding the crest of the wave and thus always experiencing an accelerating field. The world’s longest electron linac is the 3.2-kilometre (2-mile) machine at the Stanford (University) Linear Accelerator Center, Menlo Park, Calif., U.S.; it can accelerate electrons to 50 billion electron volts (50 gigaelectron volts). Much smaller linacs, both proton and electron types, have important practical applications in medicine and in industry.

Jai Ganesh · Dark Discussions at Cafe Infinity

2440) Nikolay Semyonov

Gist:

Work

During chemical reactions, atoms and molecules regroup and form new constellations. When molecules formed during a reaction readily react with molecules present from the beginning, a chain reaction can occur. Explosions and fire are examples of chain reactions. During the 1930s Nikolay Semyonov analyzed conditions and sequences of events involved in chain reactions from a theoretical and mathematical standpoint. Among other things, he found that the theoretical results corresponded with observations of the reactions between phosphorus and oxygen and between hydrogen and oxygen.

Work

During chemical reactions, atoms and molecules regroup and form new constellations. When molecules formed during a reaction readily react with molecules present from the beginning, a chain reaction can occur. Explosions and fire are examples of chain reactions. During the 1930s Nikolay Semyonov analyzed conditions and sequences of events involved in chain reactions from a theoretical and mathematical standpoint. Among other things, he found that the theoretical results corresponded with observations of the reactions between phosphorus and oxygen and between hydrogen and oxygen.

Summary

Nikolay Nikolayevich Semyonov (born April 15 [April 3, Old Style], 1896, Saratov, Russia—died Sept. 25, 1986, Moscow, U.S.S.R.) was a Soviet physical chemist who shared the 1956 Nobel Prize for Chemistry with Sir Cyril Hinshelwood for research in chemical kinetics. He was the second Soviet citizen (after the émigré writer Ivan Bunin) to receive a Nobel Prize.

Semyonov was educated in St. Petersburg, graduating from the city’s university in 1917, the year of the Russian Revolution, and taught for a time at the University of Tomsk in western Siberia. Associated with the Leningrad A.F. Ioffe Physicotechnical Institute from 1920 to 1931, he became a professor at the Leningrad (St. Petersburg) Polytechnic Institute in 1928. He was director of the Institute of Chemical Physics at the Academy of Sciences of the U.S.S.R. after 1931 and became a professor at Moscow State University in 1944.

Like Hinshelwood, Semyonov conducted research on the mechanism of chemical chain reactions and their significance in relation to explosions. Semyonov was the first to show that chain reactions are the norm in chemical transformations of matter. He published the influential book O nekotorykh problemakh khimicheskoy kinetiki i reaktsionnoy sposobnosti (1954; Some Problems in Chemical Kinetics and Reactivity).

Details

Nikolay Nikolayevich Semyono , sometimes Semenov, Semionov or Semenoff (15 April [O.S. 3 April] 1896 – 25 September 1986) was a Soviet physicist and chemist. Semyonov was awarded the 1956 Nobel Prize in Chemistry for his work on the mechanism of chemical transformation.

Life and career

Semyonov was born in Saratov, the son of Yelena Dmitrieva and Nikolai Aleksandrovich Semyonov. He graduated from the department of physics of Petrograd University (1913–1917), where he was a student of Abram Fyodorovich Ioffe. In 1918, he moved to Samara, where he was enlisted into Kolchak's White Army during Russian Civil War.

Semyonov published his first research paper in 1916 and became a lecturer at the University of Tomsk in western Siberia.

After graduating from Saint Petersburg State University, he worked as an assistant and lecturer at the Tomsk and Tomsk University Institute of Technology, where he published his first research paper in 1916. He returned to western Siberia, Petrograd and took charge of the electron phenomena laboratory of the Petrograd Physico-Technical Institute in 1920. He also became the vice-director of the institute. In 1921, he married philologist Maria Boreishe-Liverovsky (student of Zhirmunsky). She died two years later. On September 15, 1924, Nikolay married Maria's niece, Natalia Nikolayevna Burtseva. They had two children, son Yuri and daughter Lyudmila.

During that difficult time, Semyonov, together with Pyotr Kapitsa, discovered a way to measure the magnetic field of an atomic nucleus (1922). Later the experimental setup was improved by Otto Stern and Walther Gerlach and became known as Stern–Gerlach experiment.

In 1925, Semyonov, together with Yakov Frenkel, studied kinetics of condensation and adsorption of vapors. In 1927, he studied ionisation in gases and published an important book, Chemistry of the Electron. In 1928, he, together with Vladimir Fock, created a theory of thermal disruptive discharge of dielectrics.

In 1927, Semyonov studied the ionization of gases, the chemistry of the electron. In 1928, he created the theory of the broken discharge of dielectrics with Vladimir Fock.

He lectured at the Petrograd Polytechnical Institute and was appointed Professor in 1928. In 1931, he organized the Institute of Physical Chemistry of the USSR Academy of Sciences (which moved to Chernogolovka in 1943) and became its first director. In 1932, he became a full member of the Soviet Academy of Sciences.

The ideas of Semyonov have been applied in the science of reaction and production of polymerization reactions. His ideas are also applied in catalysis studies in biological systems.

Semyonov married Natalya Nikolayevna Semyonov and together they both have a son and a daughter. Semyonov died on September 25, 1986, in Moscow, and was buried at the Novodevichy Cemetery.

Significant works

Semyonov's outstanding work on the mechanism of chemical transformation includes an exhaustive analysis of the application of the chain theory to varied reactions (1934–1954) and, more significantly, to combustion processes. He proposed a theory of degenerate branching, which led to a better understanding of the phenomena associated with the induction periods of oxidation processes. He spent most of his career focusing and developing the field of chemical chain reactions.

Semyonov wrote two important books outlining his work. Chemical Kinetics and Chain Reactions was published in 1934, with an English edition in 1935. It was the first book in the U.S.S.R. to develop a detailed theory of unbranched and branched chain reactions in chemistry. Some Problems of Chemical Kinetics and Reactivity, first published in 1954, was revised in 1958; there are also English, American, German, and Chinese editions. He is the only Soviet/Russian Chemistry Nobel Laureate, who received the Nobel Prize in Chemistry (together with Sir Cyril N. Hinshelwood) for his work in 1956.

Semyonov had long been a supporter of the Communist Party and the Soviet Union. After the Bulletin of the Atomic Scientists accused the Soviet Union of heavy scientific censorship in 1953, he coauthored the Soviet response which denied all accusations. He is also noted as being the most famous signatory to a 1971 public letter from Soviet scientists to United States president Richard Nixon, on displeasure in the murder trial of Angela Davis.

Semyonov trained Russian organometallic chemist Alexander Shilov, who discovered platinum catalyzed C-H activation.

Jai Ganesh · This is Cool

2503) South Pole

Gist

The South Pole, located at the southernmost point on Earth (90°S) in Antarctica, is an extremely cold, high-altitude (~9,300 ft elevation) desert. It has a population of roughly 50 people in winter and hundreds in summer, supported by the U.S. Amundsen-Scott Station. Key challenges include extreme, life-threatening temperatures (down to
),6 months of darkness, and absolute isolation.

Summary

The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is the point in the Southern Hemisphere where the Earth's axis of rotation meets its surface. It is called the True South Pole to distinguish from the south magnetic pole.

The South Pole is by definition the southernmost point on the Earth, lying antipodally to the North Pole. It defines geodetic latitude 90° South, as well as the direction of true south. At the South Pole all directions point North; all lines of longitude converge there, so its longitude can be defined as any degree value. No time zone has been assigned to the South Pole, so any time can be used as the local time. Along tight latitude circles, clockwise is east and counterclockwise is west. The South Pole is at the center of the Southern Hemisphere. Situated on the continent of Antarctica, it is the site of the United States Amundsen–Scott South Pole Station, which was established in 1956 and has been permanently staffed since that year.

Because the South Pole is covered by an ice sheet roughly 3.2 km (2.0 mi) thick that is slowly moving, the geographic marker must be moved several meters each year. Also, buildings slowly become buried in snow because it does not melt. There is a marker at the geographic South Pole placed each year, and also a Ceremonial South Pole marked with various flags and a special post.

Details

The South Pole is the southernmost point on Earth. It is the precise point of the southern intersection of Earth's axis and Earth's surface.

From the South Pole, all directions are north. Its latitude is 90 degrees south, and all lines of longitude meet there (as well as at the North Pole).

The South Pole is located on Antarctica, one of Earth's seven continents. Although land at the South Pole is only about a hundred meters above sea level, the ice sheet above it is roughly 2,700-meters (9,000-feet) thick. This elevation makes the South Pole much colder than the North Pole, which sits in the middle of the Arctic Ocean. In fact, the warmest temperature ever recorded at the South Pole was a freezing -12.3 degrees Celsius (9.9 degrees Fahrenheit).

The South Pole is close to the coldest place on Earth. The coldest temperature recorded at the South Pole, -82.8 degrees Celsius (-117.0 degrees Fahrenheit), is still warmer than the coldest temperature ever recorded, -89.2 degrees Celsius (-128.6 degrees Fahrenheit). That temperature was recorded at the Russian Vostok Research Station, about 1,300 kilometers (808 miles) away.

Because Earth rotates on a tilted axis as it revolves around the sun, sunlight is experienced in extremes at the poles. In fact, the South Pole experiences only one sunrise (at the September equinox) and one sunset (at the March equinox) every year. From the South Pole, the sun is always above the horizon in the summer and below the horizon in the winter. This means the region experiences up to 24 hours of sunlight in the summer and 24 hours of darkness in the winter.

Due to plate tectonics, the exact location of the South Pole is constantly moving. Plate tectonics is the process of large slabs of Earth's crust moving slowly around the planet, bumping into and pulling apart from one another.

Over billions of years, Earth's continents have shifted together and drifted apart. Millions of years ago, land that today is the east coast of South America was at the South Pole. Today, the ice sheet above the South Pole drifts about 10 meters (33 feet) every year.

Amundsen–Scott South Pole Station

Compared to the North Pole, the South Pole is relatively easy to travel to and study. The North Pole is in the middle of the Arctic Ocean, while the South Pole is on a stable piece of land.

The United States has had scientists working at Amundsen–Scott South Pole Station since 1956. Between 50 and 200 scientists and support staff live at the this research station at any given time. The station itself does not sit on the ground or ice sheet. It is able to adjust its elevation, to prevent it from being buried in snow, which accumulates at a rate of about 20 centimeters (eight inches) every year, and does not melt.

In the winter, the Amundsen–Scott South Pole Station is completely self-sufficient. The dark sky, freezing temperatures, and gale-force winds prevent most supplies from being flown or trekked in. All food, medical supplies, and other material must be secured before the long Antarctic winter. The station's energy is provided by three enormous generators that run on jet fuel.

In winter, stores of food are supplemented by the Amundsen–Scott South Pole Station's greenhouse. Vegetables in the greenhouse are grown with hydroponics, in a nutrient solution instead of soil.

Some of the earliest discoveries made at South Pole research stations helped support the theory of continental drift, the idea that continents drift apart and shift together. Rock samples collected near the South Pole and throughout Antarctica match samples dated to the same time period collected at tropical latitudes. Geologists conclude that the samples formed at the same time and the same place, and were torn apart over millions of years, as the planet split into different continents.

Today, the Amundsen–Scott South Pole Station is host to a wide variety of research. The relatively undisturbed ice sheet maintains a pristine record of snowfalls, air quality, and weather patterns. Ice cores provide data for glaciologists, climatologists, and meteorologists, as well as scientists tracking patterns in climate change.

The South Pole has low temperatures and humidity and high elevation, making it an outstanding place to study astronomy and astrophysics. The South Pole Telescope studies low-frequency radiation, such as microwaves and radio waves. The South Pole Telescope is one of the instruments designed measure the cosmic microwave background (CMB)–faint, diffuse radiation left over from the Big Bang.

Astrophysicists also search for tiny particles called neutrinos at the South Pole. Neutrinos interact very, very weakly with all other matter. Neutrino detectors therefore must be very large to detect a measurable number of the particles. The Amundsen–Scott South Pole Station's IceCube Neutrino Detector has more than 80 "strings" of sensors reaching as deep as 2,450 meters (8,038 feet) beneath the ice. It is the largest neutrino detector in the world.

Ecosystems at the South Pole

Although the Antarctic coast is teeming with marine life, few biologists conduct research at the Amundsen–Scott South Pole Station. The habitat is far too harsh for most organisms to survive.

In fact, the South Pole sits in the middle of the largest, coldest, driest, and windiest desert on Earth. More temperate parts of this desert (called either East Antarctica or Maudlandia) support native flora such as moss and lichen, and organisms such as mites and midges. The South Pole itself has no native plant or animal life at all. Sometimes, however, seabirds such as skuas can be spotted if they are blown off-course.

Exploration

The early 20th century's "Race to the Pole" stands as a symbol of the harrowing nature of polar exploration.

European and American explorers had attempted to reach the South Pole since British Capt. Robert Falcon Scott's expedition of 1904. Scott, along with fellow Antarctic explorers Ernest Shackleton and Edward Wilson, came within 660 kilometers (410 miles) of the pole, but turned back due to weather and inadequate supplies.

Shackleton and Scott were determined to reach the pole. Scott worked with scientists, intent on using the best techniques to gather data and collect samples.

Shackleton also conducted scientific surveys, although his expeditions were more narrowly focused on reaching the South Pole. He came within 160 kilometers (100 miles) of the pole in 1907, but again had to turn back due to weather.

Scott gathered public support and public funding for his 1910 Terra Nova expedition. He secured provisions and scientific equipment. In addition to the sailors and scientists on his team, the Terra Nova expedition also included tourists—guests who helped finance the voyage in exchange for taking part in it.

On the way to Antarctica, the Terra Nova expedition stopped in Australia to take on final supplies. Here, Scott received a surprising telegram from Norwegian explorer Roald Amundsen: "Beg leave to inform you Fram [Amundsen's ship] proceeding Antarctic."

Amundsen was apparently racing for the pole, ahead of Scott, but had kept all preparation secret. His initial ambition, to be the first to reach the North Pole, had been thwarted by American explorers Frederick Cook and Robert Peary, both of whom claimed to reach the North Pole first. (Both claims are now disputed, and Amundsen's flight over the North Pole is generally recognized as the first verified journey there.)

The Terra Nova and Fram expeditions arrived in Antarctica about the same time, in the middle of the Antarctic summer (January). They set up base camps about 640 kilometers (400 miles) apart. As they proceeded south, both expeditions established resupply depots with supplies for their return journey. While Scott's team stuck to a route forged by Shackleton years earlier, Amundsen took a new route.

Scott proceeded with scientific and expeditionary equipment hauled by dogs, ponies, and motor sledges. The motorized equipment soon broke down, and the ponies could not adapt to the harsh Antarctic climate. Even the sled dogs became weary. All the ponies died, and most members of the expedition turned back. Only four men from the Terra Nova expedition (including Scott's friend Wilson) proceeded with Scott to the pole.

Amundsen traveled by dogsled, with a team of explorers, skiers, and mushers. The foresight and navigation paid off: Amundsen reached the pole in December 1911. He called the camp Polheim, and the entire Fram expedition successfully returned to their resupply depots, ship, and Norway.

More than a month later, Scott reached the South Pole, only to be met by Amundsen's camp—he had left a tent, equipment, and supplies for Scott, as well as a note for the King of Norway to be delivered if the Fram expedition failed to make it back.

Disheartened, Scott's team slowly headed back north. They faced colder temperatures and harsher weather than Amundsen's team. They had fewer supplies. Suffering from hunger, hypothermia, and frostbite, all members of Scott's South Pole expedition died fewer than 18 kilometers (11 miles) from a resupply depot.

American explorer Richard E. Byrd became the first person to fly over the South Pole, in 1926, and the Amundsen–Scott South Pole Station was established 30 years later.

However, the next overland expedition to the South Pole was not made until 1958, more than 40 years after Amundsen and Scott's deadly race. The 1958 expedition was led by legendary New Zealand mountaineer Sir Edmund Hillary, who had become the first person to scale Mount Everest in 1953.

Transportation to the South Pole

Almost all scientists and support personnel, as well as supplies, are flown in to the South Pole. Hardy military aircraft usually fly from McMurdo Station, an American facility on the Antarctic coast and the most populated area on the continent. The extreme and unpredictable weather around the pole can often delay flights.

In 2009, the U.S. completed construction of the South Pole Traverse. Also called the McMurdo-South Pole Highway, this stretch of unpaved road runs more than 1,600 kilometers (995 miles) over the Antarctic ice sheet, from McMurdo Station to the Amundsen–Scott South Pole Station. It takes about 40 days for supplies to reach the pole from McMurdo, but the route is far more reliable and inexpensive than air flights. The highway can also supply much heavier equipment (such as that needed by the South Pole's astrophysics laboratories) than aircraft.

Resources and Territorial Claims

The entire continent of Antarctica has no official political boundaries. Seven countries made defined claims to Antarctic territory prior to the Antarctic Treaty of 1959, which does not legally recognize any claims.

Additional Information

The pole is situated about 1,300km (800 miles) inland from the nearest open sea, it is at an altitude of 2,835m (9,300ft) above sea level due to the enormous thickness of the Antarctic ice sheet. The bedrock at the pole is thought to actually be about 57m (187ft) below sea level, in part due to the weight of all that ice pushing it down.

At the surface at the South Pole, there is just snow and ice, there are no other natural significant features, no mountains sticking through the ice (there are hills and mountains beneath the ice, but they aren't tall enough to reach through) no rock, no solid ground, just a vast endless plateau of more snow and more ice.

Oh yes, and a huge human settlement that is the Amundsen-Scott South Pole Station. This American run scientific station was established in 1956 and has been permanently manned ever since then. The current station is the third to be built, work started on it in 2003. In addition to the main station building there is a large collection of other structures in the area. Some are specifically designed and constructed scientific buildings, others are sturdy insulated tents that are used for temporary summer-only accommodation. There are cabooses or converted shipping containers that are fitted out for a particular purpose or scientific experiment.

south-pole.png?w=630&h=622&fit=clip&crop=faces%2Cfocalpoint

Jai Ganesh · Science HQ

Intravenous Infusion

Gist

IV infusion is the rapid, direct delivery of fluids, medications, or nutrients into the bloodstream via a vein, ensuring 100% absorption compared to oral intake. It is used to treat severe dehydration, electrolyte imbalances, or to administer specialized medication. Common types include hydration, blood products, and medication, often administered by professionals in hospitals or clinics.

The three main types of infusion administration routes are Intravenous (IV) (directly into a vein), Intramuscular (IM) (into a muscle), and Subcutaneous (SQ) (into the fatty tissue under the skin), with Epidural (into the spine) being another important method, all used to deliver medication when oral intake isn't possible or effective. These routes differ in how quickly they deliver drugs, with IV being the fastest, followed by IM, then SQ for slower absorption.

Summary

Intravenous (IV) fluid therapy plays a vital role in modern medical practice, particularly in critical care management. This review aims to summarize the composition, indications, and contraindications of IV fluids, serving as a useful resource for healthcare professionals.

Results:

IV fluids can be administered for various reasons, including resuscitation, correction of electrolyte imbalances, or more critical cases. They can be divided into 2 categories: crystalloids and colloids. Crystalloids, in turn, can be subdivided into unbalanced solutions, such as salines (0.45%, 0.9%, 3%, and 20%) and dextrose 5%, or balanced solutions, such as Ringer lactate and polyelectrolytic solutions. Colloids can be derived from plasma, such as 5% albumin, or semisynthetic, such as 4% modified fluid gelatin. Crystalloids are generally more cost-effective, have a lower risk of allergic reactions, and are more readily available than colloids. However, the use of each solution should be individualized based on the patient's specific needs and corresponding conditions.

Conclusions:

It is essential to have a thorough understanding of available IV fluid solutions to select the best option for each patient's condition at any given time. This review summarizes the most relevant information to guide these decisions. Future research should develop IV fluids that combine the benefits of colloids and crystalloids for safer, more personalized, and cost-effective treatments.

Details

Intravenous therapy (abbreviated as IV therapy) is a medical process that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrients for those who cannot, or will not—due to reduced mental states or otherwise—consume food or water by mouth. It may also be used to administer medications or other medical therapy such as blood products or electrolytes to correct electrolyte imbalances. Attempts at providing intravenous therapy have been recorded as early as the 1400s, but the practice did not become widespread until the 1900s after the development of techniques for safe, effective use.

The intravenous route is the fastest way to deliver medications and fluid replacement throughout the body as they are introduced directly into the circulatory system and thus quickly distributed. For this reason, the intravenous route of administration is also used for the consumption of some recreational drugs. Many therapies are administered as a "bolus" or one-time dose, but they may also be administered as an extended infusion or drip. The act of administering a therapy intravenously, or placing an intravenous line ("IV line") for later use, is a procedure which should only be performed by a skilled professional. The most basic intravenous access consists of a needle piercing the skin and entering a vein which is connected to a syringe or to external tubing. This is used to administer the desired therapy. In cases where a patient is likely to receive many such interventions in a short period (with consequent risk of trauma to the vein), normal practice is to insert a cannula which leaves one end in the vein, and subsequent therapies can be administered easily through tubing at the other end. In some cases, multiple medications or therapies are administered through the same IV line.

IV lines are classified as "central lines" if they end in a large vein close to the heart, or as "peripheral lines" if their output is to a small vein in the periphery, such as the arm. An IV line can be threaded through a peripheral vein to end near the heart, which is termed a "peripherally inserted central catheter" or PICC line. If a person is likely to need long-term intravenous therapy, a medical port may be implanted to enable easier repeated access to the vein without having to pierce the vein repeatedly. A catheter can also be inserted into a central vein through the chest, which is known as a tunneled line. The specific type of catheter used and site of insertion are affected by the desired substance to be administered and the health of the veins in the desired site of insertion.

Placement of an IV line may cause pain, as it necessarily involves piercing the skin. Infections and inflammation (termed phlebitis) are also both common side effects of an IV line. Phlebitis may be more likely if the same vein is used repeatedly for intravenous access, and can eventually develop into a hard cord which is unsuitable for IV access. The unintentional administration of a therapy outside a vein, termed extravasation or infiltration, may cause other side effects.

Additional Information

Most children will have an intravenous (IV) infusion at some point in hospital. We think it is helpful to explain what an infusion is and what it involves, so it is less scary for your child. This page from Great Ormond Street Hospital (GOSH) describes how infusions are used at GOSH, how they are inserted and what to expect when your child has one.An intravenous (IV) infusion is a way of delivering fluid or medicine directly into your child’s bloodstream. This enables the fluid or medicine to get into your child’s system much quicker than taking it by mouth. We use an infusion when a child cannot swallow medicine by mouth or it is better to give it into the bloodstream.

An IV infusion consists of various bits of equipment joined together. The first bit is a cannula (thin, plastic tube) which is put into a vein, usually in their hand or arm. The cannula is then connected to a longer, wider tube which, in turn, is joined to a bag containing the fluid or medicine.

This bag is attached to a machine, which helps to make sure the correct amount of fluid or medicine is given. The machine and bag are hung on a drip stand on wheels so that gravity helps the fluid or medicine.

How is an IV infusion set up?

The first stage is to insert a cannula into a vein.

Most children and young people at GOSH have local anaesthetic cream put on their skin before a cannula is inserted. This takes up to an hour to make the skin numb and is then wiped off.

Alternatively, some children prefer a cold spray, which only takes a few seconds to work but wears off quickly too.

The next stage is to find the right vein to use – usually a vein in the wrist or back of the hand. The nurse will usually put a tight band (tourniquet) around the arm so that the veins stand out better.

They will feel the back of your child’s hand or lower arm to find the best vein and clean the skin over it with an alcohol wipe. They will quickly insert a needle into the vein – this contains the cannula – and remove the needle, leaving the cannula in the vein.

The nurse will usually give the cannula a quick flush of saline (salt water) solution to check it is in the right place and prepare it for the drip. They will make the cannula secure with a see-through dressing and medical sticky tape, before connecting the cannula to a longer, wider piece of tubing called a ‘giving set’. This has a plastic spike on the end so it can be connected to an IV bag.

Finally, the nurse will secure the cannula on your child’s arm or wrist with a splint and bandage – this will stop the cannula being dislodged.

The nurse will connect the cannula to the giving set, thread the longer, wider tube through an IV pump and program the flow rate. The fluid will drip regularly into the drip chamber, through the machine and into your child’s bloodstream.

IV pumps have lots of alarms to tell your nurse about any problems or that the fluid or medicine has all been delivered. The nurse will be listening out for alarms so do not try to turn them off.

Sometimes the medicine can leak out of the vein (extravasation), which can be harmful, depending on the medicine that has leaked. If your child complains of pain or stinging near the cannula, or you notice any redness to the area and the surrounding area, tell the nurse immediately.

All infusions are connected in the same way using the spike and programmed into the IV pump.

When your child no longer needs any IV infusions and the cannula isn’t needed anymore, the nurse will disconnect the tubing from the cannula and throw away the IV bag and giving set.

They will remove the see-through dressing and medical sticky tape, then press down on the vein with gauze or cotton wool while they pull out the cannula. They will tape the gauze or cotton wool in place – you should leave this in place for 30 minutes or so.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#10763. What does the term in Biology Genome mean?

#10764. What does the term in Biology Genotype mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#5959. What does the adjective intractable mean?

#5960. What does the adjective intravenous mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2576. What does the medical term Fecal impaction mean?

Jai Ganesh · Dark Discussions at Cafe Infinity

Come Quotes - XII

1. I am a collection of thoughts and memories and likes and dislikes. I am the things that have happened to me and the sum of everything I've ever done. I am the clothes I wear on my back. I am every place and every person and every object I have ever come across. I am a bag of bones stuck to a very large rock spinning a thousand miles an hour. - Macaulay Culkin

2. The goal towards which the pleasure principle impels us - of becoming happy - is not attainable: yet we may not - nay, cannot - give up the efforts to come nearer to realization of it by some means or other. - Sigmund Freud

3. Comparisons are really no good in sport, especially if it is a comparison between different eras and generations, for there are so many variables that come into play, starting from the quality of the opposition to playing conditions. - Sunil Gavaskar

4. Madam, I have come from a country where people are hanged if they talk. - Leonhard Euler

5. The revolutionary breakthrough will come with rockets that are fully and rapidly reusable. We will never conquer Mars unless we do that. It'll be too expensive. The American colonies would never have been pioneered if the ships that crossed the ocean hadn't been reusable. - Elon Musk

6. There's no point in making predictions. It's not worth speculating because nothing is set in stone and things change all the time in football. Today there are opportunities that no one knows if they will come round again in the future. - Cristiano Ronaldo

7. All great and beautiful work has come of first gazing without shrinking into the darkness. - John Ruskin

8. We all keep dreaming, and luckily, dreams come true. - Katie Holmes.

Jai Ganesh · Jokes

Q: How did Reese eat her ice cream?
A: Witherspoon.
* * *
Q: What's the difference between a pizza and my pizza jokes?
A: My pizza jokes can't be topped!
* * *
Q: How do you know your close to a Frito Lay factory?
A: Because of the chips and dip in the road.
* * *
Q: What are the 4 major food groups?
A: Pizza, Coffee, Chocolate and Men.
* * *
Q: Why do you always bring a bag of chips to a party?
A: In queso emergency.
* * *

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6356.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9862.

Jai Ganesh · Exercises

Hi,

2716.

Jai Ganesh · This is Cool

Boiler

Gist

A boiler is a closed pressure vessel that heats water or other liquids to produce hot water or steam for heating, sanitation, or power generation. Utilizing energy sources like gas, oil, coal, or electricity, it acts as a heat exchanger, transferring heat from combustion to water. Key types include fire-tube (hot gases inside tubes) and water-tube (water inside tubes) boilers.

Boilers heat water to create steam or hot water for various applications, primarily for heating buildings (central heating, radiators) and driving industrial processes like power generation, cooking, sterilizing, and running turbines in factories, making them essential for both homes and large-scale manufacturing. They convert fuel (gas, oil, coal, biomass) or electricity into thermal energy for these diverse needs, from simple domestic hot water to complex pharmaceutical production.

Summary

A boiler is an enclosed vessel that provides a means for combustion and transfers heat to water until it becomes hot water or steam. The hot water or steam under pressure is then usable for transferring the heat to a process.

Water is useful and cheap medium for transferring heat to a process. When water is boiled into steam its volume increases about 1,600 times, producing a force that is almost as explosive as gunpowder. This causes the boiler to be extremely dangerous equipment and should be treated carefully.

Liquid when heated up to the gaseous state this process is called evaporation.

The heating surface is any part of the boiler; hot gases of combustion are on one side and water on the other. Any part of the boiler metal that actually contributes to making steam is heating surface. The amount of heating surface of a boiler is expressed in square meters. The larger the heating surface a boiler has, the more efficient it becomes.

The boiler system is made up of :

1. Feed water system

2. Steam system

3. Fuel system

The feed water system provides water to the boiler and regulates it automatically to meet the steam demand. The water supplied to boiler that is converted to steam is called feed water. The sources of feed water are:

1. Condensate or condensed steam returned from the processes

2. Makeup water which is the raw water which must come from outside the boiler room and plant processes.

The steam system collects and controls the steam produced in the boiler. Steam is directed through a piping system to the point of use. Throughout the system, steam pressure is regulated using valves and checked with steam pressure gauges.

The fuel system includes all equipment used to provide fuel to generate the necessary heat. The equipments required in the fuel system depend on the type of fuel used in the system.

Details

A boiler is a closed vessel in which fluid (generally water) is heated. The fluid does not necessarily boil. The heated or vaporized fluid exits the boiler for use in various processes or heating applications, including water heating, central heating, boiler-based power generation, cooking, and sanitation.

Heat sources

In a fossil fuel power plant using a steam cycle for power generation, the primary heat source will be combustion of coal, oil, or natural gas. In some cases byproduct fuel such as the carbon monoxide rich offgasses of a coke battery can be burned to heat a boiler; biofuels such as bagasse, where economically available, can also be used. In a nuclear power plant, boilers called steam generators are heated by the heat produced by nuclear fission. Where a large volume of hot gas is available from some process, a heat recovery steam generator or recovery boiler can use the heat to produce steam, with little or no extra fuel consumed; such a configuration is common in a combined cycle power plant where a gas turbine and a steam boiler are used. In all cases the combustion product waste gases are separate from the working fluid of the steam cycle, making these systems examples of external combustion engines.

Materials

The pressure vessel of a boiler is usually made of steel (or alloy steel), or historically of wrought iron. Stainless steel, especially of the austenitic types, is not used in wetted parts of boilers due to corrosion and stress corrosion cracking. However, ferritic stainless steel is often used in superheater sections that will not be exposed to boiling water, and electrically heated stainless steel shell boilers are allowed under the European "Pressure Equipment Directive" for production of steam for sterilizers and disinfectors.

In live steam models, copper or brass is often used because it is more easily fabricated in smaller size boilers. Historically, copper was often used for fireboxes (particularly for steam locomotives), because of its better formability and higher thermal conductivity; however, in more recent times, the high price of copper often makes this an uneconomic choice and cheaper substitutes (such as steel) are used instead.

For much of the Victorian "age of steam", the only material used for boilermaking was the highest grade of wrought iron, with assembly by riveting. This iron was often obtained from specialist ironworks, such as those in the Cleator Moor (UK) area, noted for the high quality of their rolled plate, which was especially suitable for use in critical applications such as high-pressure boilers. In the 20th century, design practice moved towards the use of steel, with welded construction, which is stronger and cheaper, and can be fabricated more quickly and with less labour. Wrought iron boilers corrode far more slowly than their modern-day steel counterparts, and are less susceptible to localized pitting and stress-corrosion. That makes the longevity of older wrought-iron boilers far superior to that of welded steel boilers.

Cast iron may be used for the heating vessel of domestic water heaters. Although such heaters are usually termed "boilers" in some countries, their purpose is usually to produce hot water, not steam, and so they run at low pressure and try to avoid boiling. The brittleness of cast iron makes it impractical for high-pressure steam boilers.

Energy

The source of heat for a boiler is combustion of any of several fuels, such as wood, coal, oil, or natural gas. Electric steam boilers use resistance- or immersion-type heating elements. Nuclear fission is also used as a heat source for generating steam, either directly (BWR) or, in most cases, in specialised heat exchangers called "steam generators" (PWR). Heat recovery steam generators (HRSGs) use the heat rejected from other processes such as gas turbine.

PWR : Pressurized Water Reactor.
BWR : Boiling Water Reactor.
HRGS : Heat Recovery Steam Generators.

Additional Information:

What is a Boiler?

A pressure vessel that provides a heat transfer surface (generally a set of tubes) between the combustion products and the water. A boiler is usually integrated into a system with many components.

Why use a Boiler?

Boilers are used to produce steam. The generation part of a steam system uses a boiler to add energy to a feedwater supply to generate steam. The energy is released from the combustion of fossil fuels or from process waste heat.

Where are Boilers Used?

Anywhere you are creating heat and/or steam, you will probably find a boiler. ABMA (American Boilers Manufacturers Association) members produce large boilers for the commercial, industrial, utility sector and more. Boiler systems are used to create pulp & paper, generate electricity and process foods. The complexity significantly increases as you increase the size and need for greater performance of the boiler system.

What are the major components of the Boiler System?

The boiler itself is a main component of a generation system that also includes the fuel supply, combustion air system, feedwater system, and exhaust gases venting system. ABMA members also manufacture the following components.

* Burner
* Controls
* Deaerator
* Economizer
* Fan
* Heat Exchanger
* Instrumentation
* Stoker
* Tubes

What are the basic types of Boilers?

There are two basic types of boilers: firetube and watertube. The fundamental difference between these boiler types is which side of the boiler tubes contain the combustion gases or the boiler water/steam.

Firetube Boiler

In firetube boilers, the combustion gases pass inside boiler tubes, and heat is transferred to water between the tubes and the outer shell. Today, larger firetube boilers are over 1,500 boiler horsepower (about 50,000 pounds per hour. Firetube boilers are often characterized by their number of passes, referring to the number of times the combustion (or flue) gases flow the length of the pressure vessel as they transfer heat to the water. The turnaround zones can be either dryback or waterback. In dryback designs, the turnaround area is refractory-lined. In waterback designs, this turnaround zone is water-cooled, eliminating the need for the refractory lining.

Watertube Boiler

In watertube boilers, boiler water passes through the tubes while the exhaust gases remain in the shell side, passing over the tube surfaces. Because tubes can typically withstand higher internal pressure than the large chamber shell in a firetube, watertube boilers are used where high steam pressures (3,000 psi, sometimes higher) are required. Watertube boilers are also capable of high efficiencies and can generate saturated or superheated steam. In fact, the ability of watertube boilers to generate superheated steam makes these boilers particularly attractive in applications that require dry, high-pressure, high energy steam, including steam turbine power generation. The performance characteristics of watertube boilers make them highly favorable in process industries, including chemical manufacturing, pulp and paper manufacturing, and refining. Although firetube boilers account for the majority of boiler sales in terms of units, watertube boilers account for the majority of boiler capacity.

Waste Heat Recovery Boiler (WHRB)

These boilers may be either firetube or watertube design and use heat that would otherwise be discarded to generate steam. Typical sources of heat for WHRBs include exhaust gases or high-temperature products from an external manufacturing process in refineries and chemical manufacturing facilities, or combustion of a waste fuel in the boiler furnace.

Heat Recovery Steam Generators (HRSGs)

HRSGs transfer energy from the exhaust of a gas turbine to an unfired or supplementary fired heat-recovery steam generator to produce steam. Exhaust gases leave the gas turbine at temperatures of 1,000°F (538°C) or higher and can represent more than 75% of the total fuel energy input. This energy can be recovered by passing the gases through a heat exchanger (steam generator) to produce hot water or steam for process needs.

Jai Ganesh · Dark Discussions at Cafe Infinity

2439) Cyril N. Hinshelwood

Gist:

Work

During chemical reactions, atoms and molecules regroup and form new constellations. When molecules formed during a reaction readily react with molecules present from the beginning, a chain reaction can occur. Explosions and fire are examples of chain reactions. During the 1930s Cyril Hinshelwood analyzed conditions and sequences of events involved in chain reactions from a theoretical standpoint. Among other things, he found that the theoretical results corresponded with observations of the reaction between hydrogen and oxygen.

Summary

Sir Cyril Norman Hinshelwood (born June 19, 1897, London, Eng.—died Oct. 9, 1967, London) was a British chemist who worked on reaction rates and reaction mechanisms, particularly that of the combination of hydrogen and oxygen to form water, one of the most fundamental combining reactions in chemistry. For this work he shared the 1956 Nobel Prize for Chemistry with the Soviet scientist Nikolay Semyonov.

Hinshelwood obtained his doctorate at the University of Oxford in 1924 and became professor of chemistry there in 1937. After retiring from Oxford in 1964 he became a senior research fellow at Imperial College, London.

About 1930 Hinshelwood began investigating the complex reaction in which hydrogen and oxygen atoms combine to form water. He showed that the products of this reaction help to spread the reaction further in what is essentially a chain reaction.

He next sought to explore molecular kinetics within the bacterial cell. Upon observing the biological responses of bacteria to changes in environment, he concluded that more or less permanent changes in a cell’s resistance to a drug could be induced. This finding was important in regard to bacterial resistance to antibiotic and other chemotherapeutic agents. Hinshelwood was knighted in 1948. His publications include The Kinetics of Chemical Change in Gaseous Systems (1926) and The Chemical Kinetics of the Bacterial Cell (1946).

Details

Sir Cyril Norman Hinshelwood (19 June 1897 – 9 October 1967) was a British physical chemist and expert in chemical kinetics. His work in reaction mechanisms earned the 1956 Nobel Prize in chemistry.

Education

Born in London, his parents were Norman Macmillan Hinshelwood, a chartered accountant, and Ethel Frances née Smith. He was educated first in Canada, returning in 1905 on the death of his father to a small flat in Chelsea where he lived for the rest of his life. He then studied at Westminster City School and Balliol College, Oxford.

Career

During the First World War, Hinshelwood was a chemist in an explosives factory. He was a tutor at Trinity College, Oxford, from 1921 to 1937 and was Dr Lee's Professor of Chemistry at the University of Oxford from 1937. He served on several advisory councils on scientific matters to the British Government.

His early studies of molecular kinetics led to the publication of Thermodynamics for Students of Chemistry and The Kinetics of Chemical Change in 1926. With Harold Warris Thompson he studied the explosive reaction of hydrogen and oxygen and described the phenomenon of chain reaction. His subsequent work on chemical changes in the bacterial cell proved to be of great importance in later research work on antibiotics and therapeutic agents, and his book, The Chemical Kinetics of the Bacterial Cell was published in 1946, followed by Growth, Function and Regulation in Bacterial Cells in 1966. In 1951 he published The Structure of Physical Chemistry. It was republished as an Oxford Classic Texts in the Physical Sciences by Oxford University Press in 2005.

The Langmuir-Hinshelwood process in heterogeneous catalysis, in which the adsorption of the reactants on the surface is the rate-limiting step, is named after him. He was a senior research fellow at Imperial College London from 1964 to 1967.

Awards and honours

In addition to being named the second Dr. Lee's Professor of Chemistry at Oxford, Hinshelwood was elected Fellow of the Royal Society (FRS) in 1929, serving as president from 1955 to 1960. He was knighted in 1948 and appointed to the Order of Merit in 1960. With Nikolay Semenov of the USSR, Hinshelwood was jointly awarded the Nobel Prize in Chemistry in 1956 for his researches into the mechanism of chemical reactions. He was also an elected member of the American Academy of Arts and Sciences, the United States National Academy of Sciences, and the American Philosophical Society.

Hinshelwood was president of the Chemical Society, the Royal Society, the Classical Association, and the Faraday Society, and received numerous awards and honorary degrees. He was elected on 1 January 1960 to honorary membership of the Manchester Literary and Philosophical Society who awarded him its Dalton medal in 1966.

Personal life

Hinshelwood never married. He was fluent in seven classical and modern languages and his main hobbies were painting, collecting Chinese pottery, and foreign literature. As an artist, Hinshelwood painted scenes in Oxford, as well as portraits of Oxford University people including Harold Hartley, his doctoral supervisor, and Herbert Blakiston, the President of Trinity College. The portrait of Hartley is now owned by the Royal Society, and that of Blakiston is owned by Trinity College, as are a number of Hinshelwood's other paintings.

He died, at home, on 9 October 1967. In 1968, his Nobel Prize medal was sold by his estate to a collector, who then sold it in 1976 for $15,000. In 2017, his Nobel Prize medal was sold at auction for $128,000.

Jai Ganesh · This is Cool

2502) Maglev Train

Gist

Maglev (magnetic levitation) trains are high-speed vehicles that use electromagnetic forces to float, guide, and propel themselves 10 cm (approx. 4 inches) above a guideway instead of using wheels, axles, or traditional engines. By eliminating friction, they achieve speeds exceeding 600 km/h (373 mph), offering a quiet, low-maintenance, and energy-efficient alternative to traditional rail.

Maglev trains are significantly faster than traditional bullet trains because they use magnetic levitation to float above the tracks, eliminating friction and allowing for much higher speeds, with operational speeds over 500 km/h compared to bullet trains' 320 km/h, and test records exceeding 600 km/h.

Summary

Maglev is a a floating vehicle for land transportation that is supported by either electromagnetic attraction or repulsion. Maglevs were conceptualized during the early 1900s by American professor and inventor Robert Goddard and French-born American engineer Emile Bachelet and have been in commercial use since 1984, with several operating at present and extensive networks proposed for the future.

Maglevs incorporate a basic fact about magnetic forces—like magnetic poles repel each other, and opposite magnetic poles attract each other—to lift, propel, and guide a vehicle over a track (or guideway). Maglev propulsion and levitation may involve the use of superconducting materials, electromagnets, diamagnets, and rare-earth magnets.

Electromagnetic suspension (EMS) and electrodynamic suspension (EDS)

Two types of maglevs are in service. Electromagnetic suspension (EMS) uses the attractive force between magnets present on the train’s sides and underside and on the guideway to levitate the train. A variation on EMS, called Transrapid, employs an electromagnet to lift the train off the guideway. The attraction from magnets present on the underside of the vehicle that wrap around the iron rails of the guideway keep the train about 1.3 cm (0.5 inch) above the guideway.

Electrodynamic suspension (EDS) systems are similar to EMS in several respects, but the magnets are used to repel the train from the guideway rather than attract them. These magnets are supercooled and superconducting and have the ability to conduct electricity for a short time after power has been cut. (In EMS systems a loss of power shuts down the electromagnets.) Also, unlike EMS, the charge of the magnetized coils of the guideway in EDS systems repels the charge of magnets on the undercarriage of the train so that it levitates higher (typically in the range of 1–10 cm [0.4–3.9 inches]) above the guideway. EDS trains are slow to lift off, so they have wheels that must be deployed below approximately 100 km (62 miles) per hour. Once levitated, however, the train is moved forward by propulsion provided by the guideway coils, which are constantly changing polarity owing to alternating electrical current that powers the system.

Maglevs eliminate a key source of friction—that of train wheels on the rails—although they must still overcome air resistance. This lack of friction means that they can reach higher speeds than conventional trains. At present maglev technology has produced trains that can travel in excess of 500 km (310 miles) per hour. This speed is twice as fast as a conventional commuter train and comparable to the TGV (Train à Grande Vitesse) in use in France, which travels between 300 and 320 km (186 and 199 miles) per hour. Because of air resistance, however, maglevs are only slightly more energy efficient than conventional trains.

Benefits and costs

Maglevs have several other advantages compared with conventional trains. They are less expensive to operate and maintain, because the absence of rolling friction means that parts do not wear out quickly (as do, for instance, the wheels on a conventional railcar). This means that fewer materials are consumed by the train’s operation, because parts do not constantly have to be replaced. The design of the maglev cars and railway makes derailment highly unlikely, and maglev railcars can be built wider than conventional railcars, offering more options for using the interior space and making them more comfortable to ride in. Maglevs produce little to no air pollution during operation, because no fuel is being burned, and the absence of friction makes the trains very quiet (both within and outside the cars) and provides a very smooth ride for passengers. Finally, maglev systems can operate on higher ascending grades (up to 10 percent) than traditional railroads (limited to about 4 percent or less), reducing the need to excavate tunnels or level the landscape to accommodate the tracks.

The greatest obstacle to the development of maglev systems is that they require entirely new infrastructure that cannot be integrated with existing railroads and that would also compete with existing highways, railroads, and air routes. Besides the costs of construction, one factor to be considered in developing maglev rail systems is that they require the use of rare-earth elements (scandium, yttrium, and 15 lanthanides), which may be quite expensive to recover and refine. Magnets made from rare-earth elements, however, produce a stronger magnetic field than ferrite (iron compounds) or alnico (alloys of iron, aluminum, nickel, cobalt, and copper) magnets to lift and guide the train cars over a guideway.

Maglev systems

Several train systems using maglev have been developed over the years, with most operating over relatively short distances. Between 1984 and 1995 the first commercial maglev system was developed in Great Britain as a shuttle between the Birmingham airport and a nearby rail station, some 600 meters (about 1,970 feet) away. Germany constructed a maglev in Berlin (the M-Bahn) that began operation in 1991 to overcome a gap in the city’s public transportation system caused by the Berlin Wall; however, the M-Bahn was dismantled in 1992, shortly after the wall was taken down. The 1986 World’s Fair (Expo 86) in Vancouver included a short section of a maglev system within the fairgrounds.

Six commercial maglev systems are currently in operation around the world. One is located in Japan, two in South Korea, and three in China. In Aichi, Japan, near Nagoya, a system built for the 2005 World’s Fair, the Linimo, is still in operation. It is about 9 km (5.6 miles) long, with nine station stops over that distance, and reaches speeds of about 100 km (62 miles) per hour. The Korean Rotem Maglev runs in the city of Taejeŏn between the Taejeŏn Expo Park and the National Science Museum, a distance of 1 km (0.6 mile). The Inch’ŏn Airport Maglev has six stations and runs from Inch’ŏn International Airport to the Yongyu station, 6.1 km (3.8 miles) away. The longest commercial maglev system is in Shanghai; it covers about 30 km (18.6 miles) and runs from downtown Shanghai to Pudong International Airport. The line is the first high-speed commercial maglev, operating at a maximum speed of 430 km (267 miles) per hour. China also has two low-speed maglev system operating at speeds of 100 km (62 miles) per hour. The Changsha Maglev connects that city’s airport to a station 18.5 km (11.5 miles) away, and the S1 line of the Beijing subway system has seven stops over a distance of 9 km (6 miles).

Japan has plans to create a long-distance high-speed maglev system, the Chuo Shinkansen, which would connect Nagoya to Tokyo, a distance of 286 km (178 miles), with an extension to Osaka (438 km [272 miles] from Tokyo) planned for 2037. However, the project was delayed past its original deadline in 2027 when the governor of Shizuoka Prefecture opposed the geological survey necessary to accommodate the high-speed train, citing impacts on biodiversity and water supply (though many surmised that it was because Shizuoka was the one prefecture with no station on the line). The governor’s resignation in 2024 effectively resumed the project, with new estimates placing the Nagoya-Tokyo line’s completion in 2034. The Chuo Shinkansen is planned to travel at 500 km (310 miles) per hour and make the Tokyo-Osaka trip in 67 minutes.

Details

Maglev (derived from magnetic levitation) is a system of rail transport whose rolling stock is levitated by electromagnets rather than rolled on wheels, eliminating rolling resistance.

Compared to conventional railways, maglev trains have higher top speeds, superior acceleration and deceleration, lower maintenance costs, improved gradient handling, and lower noise. However, they are more expensive to build, cannot use existing infrastructure, and use more energy at high speeds.

Maglev trains have set several speed records. The train speed record of 603 km/h (375 mph) was set by the experimental Japanese L0 Series maglev in 2015. From 2002 until 2021, the record for the highest operational speed of a passenger train of 431 kilometres per hour (268 mph) was held by the Shanghai maglev train, which uses German Transrapid technology. The service connects Shanghai Pudong International Airport and the outskirts of central Pudong, Shanghai. At its historical top speed, it covered the distance of 30.5 kilometres (19 mi) in just over 8 minutes (average speed: 228.75 km/h).

Different maglev systems achieve levitation in different ways, which broadly fall into two categories: electromagnetic suspension (EMS) and electrodynamic suspension (EDS). Propulsion is typically provided by a linear motor. The power needed for levitation is typically not a large percentage of the overall energy consumption of a high-speed maglev system. Instead, overcoming drag takes the most energy. Vactrain technology has been proposed as a means to overcome this limitation.

Despite over a century of research and development, there are only seven operational maglev trains today — four in China, two in South Korea, and one in Japan.

Two inter-city maglev lines are currently under construction, the Chūō Shinkansen connecting Tokyo and Nagoya (with further connection to Osaka) and a line between Changsha and Liuyang in Hunan Province, China.

Additional Information

The evolution of mass transportation has fundamentally shifted human civilization. In the 1860s, a transcontinental railroad turned the months-long slog across America into a week-long journey. Just a few decades later, passenger automobiles made it possible to bounce across the countryside much faster than on horseback. And of course, during the World War I era, the first commercial flights began transforming our travels all over again, making coast-to-coast journeys a matter of hours. But rail trips in the U.S. aren't much faster today than they were a century ago. For engineers looking for the next big breakthrough, perhaps "magical" floating trains are just the ticket.

In the 21st century there are a few countries using powerful electromagnets to develop high-speed trains, called maglev trains. These trains float over guideways using the basic principles of magnets to replace the old steel wheel and track trains. There's no rail friction to speak of, meaning these trains can hit speeds of hundreds of miles per hour.

Yet high speed is just one major benefit of maglev trains. Because the trains rarely (if ever) touch the track, there's far less noise and vibration than typical, earth-shaking trains. Less vibration and friction results in fewer mechanical breakdowns, meaning that maglev trains are less likely to encounter weather-related delays.

The first patents for magnetic levitation (maglev) technologies were filed by French-born American engineer Emile Bachelet all the way back in the early 1910s. Even before that, in 1904, American professor and inventor Robert Goddard had written a paper outlining the idea of maglev levitation [source: Witschge]. It wasn't long before engineers began planning train systems based on this futuristic vision. Soon, they believed, passengers would board magnetically propelled cars and zip from place to place at high speed, and without many of the maintenance and safety concerns of traditional railroads.

The big difference between a maglev train and a conventional train is that maglev trains do not have an engine — at least not the kind of engine used to pull typical train cars along steel tracks. The engine for maglev trains is rather inconspicuous. Instead of using fossil fuels, the magnetic field created by the electrified coils in the guideway walls and the track combine to propel the train.

If you've ever played with magnets, you know that opposite poles attract and like poles repel each other. This is the basic principle behind electromagnetic propulsion. Electromagnets are similar to other magnets in that they attract metal objects, but the magnetic pull is temporary. You can easily create a small electromagnet yourself by connecting the ends of a copper wire to the positive and negative ends of an AA, C or D-cell battery. This creates a small magnetic field. If you disconnect either end of the wire from the battery, the magnetic field is taken away.

The magnetic field created in this wire-and-battery experiment is the simple idea behind a maglev train rail system. There are three components to this system:

* A large electrical power source
* Metal coils lining a guideway or track
* Large guidance magnets attached to the underside of the train.

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Jai Ganesh · This is Cool

Peregrine Falcon

Gist

As swift as a speeding arrow and more rapid than a cheetah, the peregrine falcon is the fastest member of the animal kingdom, with a diving speed of more than 200 miles per hour.

The Peregrine Falcon (Falco peregrinus) is the fastest bird, and indeed the fastest animal, in the world, reaching incredible speeds of over 320 km/h (200 mph) during its hunting dive, known as a stoop, with some recorded at nearly 390 km/h (242 mph). Its aerodynamic body and specialized nostrils allow it to achieve these speeds to catch prey mid-air.

Summary

Powerful and fast-flying, the Peregrine Falcon hunts medium-sized birds, dropping down on them from high above in a spectacular stoop. They were virtually eradicated from eastern North America by pesticide poisoning in the middle 20th century. After significant recovery efforts, Peregrine Falcons have made an incredible rebound and are now regularly seen in many large cities and coastal areas.

Cool Facts:

* People have trained falcons for hunting for over a thousand years, and the Peregrine Falcon was always one of the most prized birds. Efforts to breed the Peregrine in captivity and reestablish populations depleted during the DDT years were greatly assisted by the existence of methods of handling captive falcons developed by falconers.
* The Peregrine Falcon is a very fast flier, averaging 40-55 km/h (25-34 mph) in traveling flight, and reaching speeds up to 112 km/h (69 mph) in direct pursuit of prey. During its spectacular hunting stoop from heights of over 1 km (0.62 mi), the peregrine may reach speeds of 320 km/h (200 mph) as it drops toward its prey.
* The Peregrine Falcon is one of the most widespread birds in the world. It is found on all continents except Antarctica, and on many oceanic islands.
* The oldest recorded Peregrine Falcon was at least 19 years, 9 months old, when it was identified by its band in Minnesota in 2012, the same state where it had been banded in 1992.

Details

The peregrine falcon (Falco peregrinus), also referred to simply as the peregrine, is a bird of prey (raptor) in the family Falconidae known for its speed. A large, crow-sized falcon, it has a blue-grey back, barred white underparts and a black head. As is typical for bird-eating (avivore) raptors, peregrine falcons are sexually dimorphic, with females being considerably larger than males. Historically, the bird has also been known as the "black-cheeked falcon" in Australia, and the "duck hawk" in North America.

The breeding range includes land regions from the Arctic tundra to the tropics. It can be found nearly everywhere on Earth, except extreme polar regions, very high mountains, and most tropical rainforests. The only major ice-free landmass from which it is entirely absent is New Zealand. That makes it the world's most widespread raptor and one of the most widely found wild bird species. In fact, the only land-based bird species found over a larger geographic area, domestic and feral pigeons, owe their success to human-led introduction. Both are domesticated forms of the rock dove, and are a major prey species for peregrine populations. Due to their greater abundance in cities than most other birds, feral pigeons support many peregrine populations as a staple food source, especially in urban settings.

The peregrine is a highly successful example of urban wildlife in much of its range, taking advantage of tall buildings as nest sites, and an abundance of prey such as pigeons and ducks. Both the English and scientific names of the species mean "wandering falcon", referring to the migratory habits of many northern populations. A total of 18 or 19 regional subspecies are accepted, which vary in appearance. Disagreement existed in the past over whether the distinctive Barbary falcon was represented by two subspecies of Falco peregrinus or was a separate species, F. pelegrinoides, and several of the other subspecies were originally described as species. However, the difference in their appearance is very small, as is their genetic difference, being only about 0.6–0.8% genetically differentiated. That indicates the divergence is relatively recent, occurring during the Last Ice Age, and all major ornithological authorities now treat the Barbary falcon as a subspecies.

Although its diet consists almost exclusively of medium-sized birds, the peregrine will sometimes hunt small mammals, small reptiles, or even insects. Reaching sexual maturity at one year, it mates for life and nests in a scrape, normally on cliff edges or, in recent times, on tall human-made structures. The peregrine falcon became an endangered species in many areas because of the widespread use of various pesticides, especially DDT. Since the ban on DDT from the early 1970s, populations have recovered, supported by large-scale protection of nesting places and releases to the wild.

The peregrine falcon is a well-respected falconry bird due to its strong hunting ability, high trainability, versatility, and availability via captive breeding. It is effective on most game bird species, from small to large. It has also been used as a religious, royal, or national symbol across many eras and civilizations.

Description

The peregrine falcon has a body length of 34 to 58 cm (13–23 in) and a wingspan from 74 to 120 cm (29–47 in). The male and female have similar markings and plumage but, as with many birds of prey, the peregrine falcon displays marked sexual dimorphism in size, with the female measuring up to 30% larger than the male. Males weigh 330 to 1,000 g (12–35 oz) and the noticeably larger females weigh 700 to 1,500 g (25–53 oz). In most subspecies, males weigh less than 700 g (25 oz) and females weigh more than 800 g (28 oz), and cases of females weighing about 50% more than their male breeding mates are not uncommon. The standard linear measurements of peregrines are: the wing chord measures 26.5 to 39 cm (10.4–15.4 in), the tail measures 13 to 19 cm (5.1–7.5 in) and the tarsus measures 4.5 to 5.6 cm (1.8–2.2 in).

The back and the long pointed wings of the adult are usually bluish black to slate grey with indistinct darker barring; the wingtips are black. The white to rusty underparts are barred with thin clean bands of dark brown or black. The tail, coloured like the back but with thin clean bars, is long, narrow, and rounded at the end with a black tip and a white band at the very end. The top of the head and a "moustache" along the cheeks are black, contrasting sharply with the pale sides of the neck and white throat. The cere is yellow, as are the feet, and the beak and claws are black. The upper beak is notched near the tip, an adaptation which enables falcons to kill prey by severing the spinal column at the neck. An immature bird is much browner, with streaked, rather than barred, underparts, and has a pale bluish cere and orbital ring.

The patch of black feathers below the falcon's eyes is called the malar stripe. A 2021 study of photos from around the world showed that the malar stripe is larger in areas that receive more sunlight, and concluded that the stripe serves to improve the falcon's vision by reducing glare.

Additional Information

Peregrine falcon, (Falco peregrinus) is the most widely distributed species of bird of prey, with breeding populations on every continent except Antarctica and many oceanic islands. Sixteen subspecies are recognized. The peregrine falcon is best known for its diving speed during flight—which can reach more than 300 km (186 miles) per hour—making it not only the world’s fastest bird but also the world’s fastest animal.

Coloration is a bluish gray above, with black bars on the white to yellowish white underparts. Adult peregrines range from about 36 to 49 cm (14.2 to 19.3 inches) in length. Strong and fast, they hunt by flying high and then diving at their prey. Attaining tremendous speeds of more than 320 km (200 miles) per hour, they strike with clenched talons and kill by impact. Their prey includes ducks and a wide variety of songbirds and shorebirds. Peregrines inhabit rocky open country near water where birds are plentiful. The usual nest is a mere scrape on a ledge high on a cliff, but a few populations use city skyscrapers or tree nests built by other bird species. The clutch is three or four reddish brown eggs, and incubation lasts about a month. The young fledge in five to six weeks.

Captive peregrine falcons have long been used in the sport of falconry. After World War II the peregrine falcon suffered a precipitous population decline throughout most of its global range. In most regions, including North America, the chief cause of the decline was traced to the pesticide DDT, which the birds had obtained from their avian prey. The chemical had become concentrated in the peregrine’s tissues and interfered with the deposition of calcium in the eggshells, causing them to be abnormally thin and prone to breakage. In the British Isles, direct mortality from another pesticide, dieldrin, was the most important cause of the decline. Following the banning or great reduction in the use of most organochlorine pesticides, populations have rebounded in virtually every part of the world and now exceed historical levels in many regions.

The American peregrine falcon (F. peregrinus anatum), which once bred from Hudson Bay to the southern United States, was formerly an endangered species. It had completely vanished from the eastern United States and eastern boreal Canada by the late 1960s. After Canada had banned DDT use by 1969 and the United States by 1972, vigorous captive breeding and reintroduction programs were initiated in both countries. Over the next 30 years, more than 6,000 captive progeny were released to the wild. North American populations recovered completely, and since 1999 the peregrine has not been listed as endangered. The peregrine has been listed as a species of least concern by the International Union for Conservation of Nature (IUCN) since 2015.

Jai Ganesh · Science HQ

Tonsils

Gist

Tonsils are two oval-shaped, immune-system tissue pads located at the back of the throat that act as a first line of defense against ingested or inhaled pathogens. They commonly become inflamed (tonsillitis) due to viruses or bacteria, causing sore throat, swelling, and difficulty swallowing. Treatments include antibiotics for bacterial infections, rest, and sometimes surgical removal (tonsillectomy).

Causes of tonsil issues (tonsillitis) are primarily viral or bacterial infections, like the cold, flu, or strep throat, but can also involve tonsil stones (tonsilloliths) from trapped debris, or more rarely, tonsil cancer, linked to HPV, tobacco, and alcohol. Tonsils, as part of the immune system, often get inflamed fighting germs, especially in children, leading to symptoms like sore throat, fever, and difficulty swallowing.

(HPV: human papillomavirus)

Summary

The tonsils are a set of lymphoid organs facing into the aerodigestive tract, which is known as Waldeyer's tonsillar ring and consists of the adenoid tonsil (or pharyngeal tonsil), two tubal tonsils, two palatine tonsils, and the lingual tonsils. These organs play an important role in the immune system.

When used unqualified, the term most commonly refers specifically to the palatine tonsils, which are two lymphoid organs situated at either side of the back of the human throat. The palatine tonsils and the adenoid tonsil are organs consisting of lymphoepithelial tissue located near the oropharynx and nasopharynx (parts of the throat).

Function

Tonsils are key components of the immune system, acting as the body's first line of defense against inhaled or ingested pathogens. Located at the entrance of the respiratory and digestive tracts, they monitor and respond to microbes by initiating immune responses. The tonsils contain a dense network of immune cells including B lymphocytes, T lymphocytes, macrophages, and dendritic cells. These cells interact within specialized regions called germinal centers, which become especially active during infections. Within these centers, B cells undergo activation, class switching (changing the type of antibody they produce), and somatic hypermutation of their antibody genes to better recognize and neutralize pathogens. Tonsils have a unique lymphoepithelial structure, with immune cells embedded within epithelial tissue, creating a direct interface with the external environment. This architecture facilitates efficient sampling of incoming bacteria and viruses through specialized M cells in the epithelium. The crypts in palatine tonsils significantly increase the surface area for antigen sampling, enhancing immune surveillance. The tonsillar immune response produces various antibodies—particularly immunoglobulins like IgA, IgG, and IgM—which contribute to both local and systemic immunity. Secretory IgA is especially important as it provides mucosal protection against pathogens before they can establish infection. In essence, the tonsils serve as immune surveillance stations, training grounds for antibody-producing cells, and barriers against infection at the body's entry points.

Details

Your tonsils, located in the back of your throat, are part of your immune system. They help fight infection and disease. Sometimes, you can develop issues with your tonsils, such as pain, swelling and infection. If these issues are chronic, your healthcare provider might recommend a tonsillectomy (tonsil removal).

Overview:

What are tonsils?
Your tonsils are two round, fleshy masses in the back of your throat (pharynx). Part of your immune system, your tonsils are like lymph nodes. They help filter out germs that enter through your nose or mouth to protect the rest of your body from infection. Tonsils are also called palatine tonsils or faucial tonsils.

Sometimes tonsils can become red, swollen or infected. If this issue becomes chronic or doesn’t get better, your healthcare provider might recommend a tonsillectomy (tonsil removal). Typically, people who have their tonsils removed can still fight off infection without any problems. Your body can find other ways to combat germs.

Function:

What’s the purpose of tonsils?

The main function of tonsils is fighting infection. Your tonsils contain a lot of white blood cells, which help kill germs. As your tonsils are in the back of your throat, they can “catch” germs that enter your body through your nose or mouth.

Anatomy:

Where are your tonsils?

Your tonsils are near the back of your throat, just behind your soft palate. There are two of them — one on each side.

What do my tonsils look like?

If you still have your tonsils, you can see them when you open your mouth wide and look in the mirror. They’re oval-shaped, pinkish mounds of tissue located on each side of your throat.

What color are my tonsils?

Healthy, normal tonsils are pinkish in color. But your tonsils can appear red and swollen if they’re inflamed or infected.

How big are the average tonsils?

Tonsil size varies significantly from person to person. But based on one research study:

* The average overall tonsil size is 42.81 cubic centimeters (cu cm).
* The average tonsil size in women is 37.65 {cm}^{3}.
* The average tonsil size in men is 52.4 {cm}^{3}.

To put this into perspective, each of your tonsils is slightly larger than a marshmallow.

Conditions and Disorders:

What are some conditions that affect tonsils?

There are a few different conditions that can affect your tonsils. The most common is tonsillitis — an infection of the tonsils. Bacteria and viruses can cause tonsillitis, and the infection can be short-term (acute) or long-term (chronic). The most common tonsillitis symptoms include a sore throat and swollen tonsils.

Other conditions that can affect your tonsils include:

* Strep throat. Caused by a bacterium known as Streptococcus, strep throat can cause sore throat, neck pain and fever.
* Tonsil stones. Also called tonsilloliths, tonsil stones are small white or yellow lumps in your tonsils. They can lead to tonsil pain, bad breath or bad taste.
* Peritonsillar abscess. A pocket of infection that pushes your tonsil to the other side of your throat, a peritonsillar abscess can cause difficulty swallowing or breathing. (If this happens, contact your healthcare provider immediately. Prompt treatment is essential.)
* Mononucleosis. Caused by a herpes virus called Epstein-Barr, mononucleosis can result in swollen tonsils, sore throat, fatigue and skin rash.
* Enlarged (hypertrophic) tonsils. Larger-than-normal tonsils can block your airway, leading to snoring or sleep apnea.
* Tonsil cancer. The most common form of oropharyngeal cancer, tonsil cancer is often linked to the human papillomavirus (HPV). Symptoms include tonsil pain, a lump in your neck and blood in your saliva (spit).

Are there tests to check the health of my tonsils?

Yes. If your healthcare provider suspects an issue with your tonsils, they may recommend:

* A bacterial culture test. Your provider rubs a cotton swab on your throat and tonsils. Then, they send the sample to a lab for analysis. A throat culture can check for different bacterial infections, including tonsillitis, strep throat and pneumonia.
* Blood tests. If your provider thinks your tonsil pain is due to mononucleosis, they can request a monospot test. This blood test detects certain antibodies, which can help confirm your diagnosis. (If the monospot test comes back negative, they can check for Epstein-Barr antibodies in your blood. This can also help determine whether you have mononucleosis.)

Additional Information

The tonsils are part of the body’s immune system. Because of their location at the throat and palate, they can stop germs entering the body through the mouth or the nose. The tonsils also contain a lot of white blood cells, which are responsible for killing germs.

There are different types of tonsils:

* Palatine tonsils (tonsilla palatina)
* The adenoids (pharyngeal tonsil or tonsilla pharyngealis)
* Lingual tonsil (tonsilla lingualis)

The two palatine tonsils are found on the right and left of the back of the throat, and are the only tonsils that can be seen unaided when you open your mouth. The adenoids are found high up in the throat, behind the nose, and can only be seen through rhinoscopy (an examination of the inside of the nose). The lingual tonsil is located far back at the base of the tongue, on its back surface.

All of these tonsillar structures together are sometimes called Waldeyer's ring since they form a ring around the opening to the throat from the mouth and nose. This position allows them to prevent germs like viruses or bacteria from entering the body through the mouth or the nose. There are also more immune system cells located behind Waldeyer's ring on the sides of the throat. These cells can take on the function of the adenoids if they have been removed.

The palatine tonsils can become inflamed. Known as tonsillitis, this makes them swell up and turn very red. They often have yellowish spots on them as well. The most common symptoms are a sore throat and fever.

The palatine tonsils and the adenoids may become enlarged, especially in children. That makes it harder to breathe and causes sleep problems. Because of these problems, tonsil surgery is sometimes recommended.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#10761. What does the term in Geography Dam mean?

#10762. What does the term in Geography Dasymetric map mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#5957. What does the adjective gratifying mean?

#5958. What does the adjective au gratin mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2575. What does the medical term Prostate cancer mean?

Jai Ganesh · Dark Discussions at Cafe Infinity

Come Quotes - XI

1. You cannot mandate philanthropy. It has to come from within, and when it does, it is deeply satisfying. - Azim Premji

2. Liberty has never come from Government. Liberty has always come from the subjects of it. The history of liberty is a history of limitations of governmental power, not the increase of it. - Woodrow Wilson

3. This is my 20th year in the sport. I've known swimming and that's it. I don't want to swim past age 30; if I continue after this Olympics, and come back in 2016, I'll be 31. I'm looking forward to being able to see the other side of the fence. - Michael Phelps

4. For many, Christmas is also a time for coming together. But for others, service will come first. - Queen Elizabeth II

5. Gliders, sail planes, they're wonderful flying machines. It's the closest you can come to being a bird. - Neil Armstrong

6. Change will come slowly, across generations, because old beliefs die hard even when demonstrably false. - E. O. Wilson

7. I come from - I came from Wales, and it's a strong, butch society. We were in the war and all that. People didn't waste time feeling sorry for themselves. You had to get on with it. So my credo is get on with it. I don't waste time being soft. I'm not cold, but I don't like being, wasting my time with - life's too short. - Anthony Hopkins

8. Author: A fool who, not content with having bored those who have lived with him, insists on tormenting generations to come. - Montesquieu.

Jai Ganesh · Jokes

Q: Why did the ice cream truck break down?
A: Because of the Rocky Road.
* * *
Q: How do you learn how to make ice cream?
A: In Sunday (Sundae) School.
* * *
Q: What happened when rockers couldn't get their favorite dessert?
A: Rage against the Broken Ice Cream Machine.
* * *
Who's there?
Ice cream!
Ice cream who?
Ice cream if you throw me in the cold, cold water!
* * *
There are two types of people in this world: People who love ice cream and liars.
* * *

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9861.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6355.

Jai Ganesh · Exercises

Hi,

2715.

Math Is Fun Forum

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