Posts by Jai Ganesh

Jai Ganesh · Jokes

Q: What's Tiger Woods favorite brand of potato chips?
A: Lays.
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Q: Why did the Oreo go to the dentist?
A: Because it lost its filling.
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There are two types of people in this world: People who love pizza and liars.
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Why do we cook bacon and bake cookies?
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What's the best part of Valentines Day?
The day after when all the chocolate goes on sale.
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Knock Knock.
Who's There?
Queso!
Queso who?
Queso mistaken identity.
* * *

Jai Ganesh · This is Cool

2507) Swallow

Gist

A swallow is a small, agile bird from the family Hirundinidae, known for its aerial acrobatics, glossy blue-black backs, red throats, and long forked tails with streamers, spending most of its time catching insects in flight, building mud nests, and migrating long distances to warmer climates for winter.

Unlike Swifts, Swallows rarely venture into towns, preferring open countryside where flying insects are plentiful. They can often be seen around open water too. As autumn approaches, large groups of Swallows often congregate on overhead wires and in reedbeds before heading south, back to Africa.

Summary

Swallow is any of the approximately 90 species of the bird family Hirundinidae (order Passeriformes). A few, including the bank swallow, are called martins (see martin; see also woodswallow; for sea swallow, see tern). Swallows are small, with pointed narrow wings, short bills, and small weak feet; some species have forked tails. Plumage may be plain or marked with metallic blue or green; the sexes look alike in most species.

Swallows spend much time in the air, capturing insects; they are among the most agile of passerine birds. For nesting, swallows may use a hole or cranny in a tree, burrow into a sandbank, or plaster mud onto a wall or ledge to house three to seven white, sometimes speckled, eggs.

Swallows occur worldwide except in the coldest regions and remotest islands. Temperate-zone species include long-distance migrants. The common swallow (Hirundo rustica) is almost worldwide in migration; an American species, called barn swallow, may summer in Canada and winter in Argentina. The 10 species of Petrochelidon, which make flask-shaped mud nests, include the cliff swallow (P. pyrrhonota), the bird of San Juan Capistrano Mission, in California; as with other swallows, it has strong homing instincts.

Details

The swallows, martins, and saw-wings, or Hirundinidae, are a family of passerine songbirds found around the world on all continents, including occasionally in Antarctica. Highly adapted to aerial feeding, they have a distinctive appearance. The term "swallow" is used as the common name for Hirundo rustica in the United Kingdom and Ireland. Around 90 species of Hirundinidae are known, divided into 21 genera, with the greatest diversity found in Africa, which is also thought to be where they evolved as hole-nesters. They also occur on a number of oceanic islands. A number of European and North American species are long-distance migrants; by contrast, the West and South African swallows are nonmigratory.

This family comprises two subfamilies: Pseudochelidoninae (the river martins of the genus Pseudochelidon) and Hirundininae (all other swallows, martins, and saw-wings). In the Old World, the name "martin" tends to be used for the squarer-tailed species, and the name "swallow" for the more fork-tailed species; however, this distinction does not represent a real evolutionary separation. In the New World, "martin" is reserved for members of the genus Progne. (These two systems are responsible for the same species being called sand martin in the Old World and bank swallow in the New World.)

Taxonomy and systematics

The family Hirundinidae was introduced (as Hirundia) by the French polymath Constantine Samuel Rafinesque in 1815. The Hirundinidae are morphologically unique within the passerines, with molecular evidence placing them as a distinctive lineage within the Sylvioidea (Old World warblers and relatives). Phylogenetic analysis has shown that the family Hirundinidae is sister to the cupwings in the family Pnoepygidae. The two families diverged in the early Miocene around 22 million years ago.

Within the family, a clear division exists between the two subfamilies, the Pseudochelidoninae, which are composed of the two species of river martins, and the Hirundininae, into which the remaining species are placed. The division of the Hirundininae has been the source of much discussion, with various taxonomists variously splitting them into as many as 24 genera and lumping them into just 12. Some agreement exists that three core groups occur within the Hirundininae: the saw-wings of the genus Psalidoprocne, the core martins, and the swallows of the genus Hirundo and their allies. The saw-wings are the most basal of the three, with the other two clades being sister to each other. The phylogeny of the swallows is closely related to evolution of nest construction; the more basal saw-wings use burrows as nest, the core martins have both burrowing (in the Old World members) and cavity adoption (in New World members) as strategies, and the genus Hirundo and its allies use mud nests.

Fossil record

The oldest known fossil swallow is Miochelidon eschata from the Early Miocene of Siberia; it is the only record of Hirundinidae from the Miocene. It is likely a basal member of the family.

Description

The Hirundinidae have an evolutionarily conservative body shape, which is similar across the clade, but is unlike that of other passerines. Swallows have adapted to hunting insects on the wing by developing a slender, streamlined body and long, pointed wings, which allow great maneuverability and endurance, as well as frequent periods of gliding. Their body shapes allow for very efficient flight; the metabolic rate of swallows in flight is 49–72% lower than equivalent passerines of the same size.

Swallows have two foveae in each eye, giving them sharp lateral and frontal vision to help track prey. They also have relatively long eyes, with their length almost equaling their width. The long eyes allow for an increase in visual acuity without competing with the brain for space inside of the head. The morphology of the eye in swallows is similar to that of a raptor.

Like the unrelated swifts and nightjars, which hunt in a similar way, they have short bills, but strong jaws and a wide gape. Their body lengths range from about 10–24 cm (3.9–9.4 in) and their weight from about 10–60 g (0.35–2.12 oz). The smallest species by weight may be the Fanti sawwing, at a mean body mass of 9.4 g (0.33 oz) while the purple martin and southern martin, which both weigh in excess of 50 g (1.8 oz) on average, rival one another as the heaviest swallows. The wings are long, pointed, and have nine primary feathers. The tail has 12 feathers and may be deeply forked, somewhat indented, or square-ended. A long tail increases maneuverability, and may also function as a sexual adornment, since the tail is frequently longer in males. In barn swallows, the tail of the male is 18% longer than those of the female, and females select mates on the basis of tail length.

Their legs are short, and their feet are adapted for perching rather than walking, as the front toes are partially joined at the base. Swallows are capable of walking and even running, but they do so with a shuffling, waddling gait. The leg muscles of the river martins (Pseudochelidon) are stronger and more robust than those of other swallows. The river martins have other characteristics that separate them from the other swallows. The structure of the syrinx is substantially different between the two subfamilies; and in most swallows, the bill, legs, and feet are dark brown or black, but in the river martins, the bill is orange-red and the legs and feet are pink.

The most common hirundine plumage is glossy dark blue or green above and plain or streaked underparts, often white or rufous. Species that burrow or live in dry or mountainous areas are often matte brown above (e.g. sand martin and crag martin). The sexes show limited or no sexual dimorphism, with longer outer tail feathers in the adult male probably being the most common distinction.

The chicks hatch naked and with closed eyes. Fledged juveniles usually appear as duller versions of the adult.

Additional Information:

About

The swallow, or 'barn swallow', is a common summer visitor, arriving in April and leaving in October. It builds mud and straw nests on ledges, often in farm buildings and outhouses, or under the eaves of houses. Swallows are widespread and common birds of farmland and open pasture near water. They are agile fliers, feeding on flying insects while on the wing. Before they migrate back to their wintering grounds in Africa, they can be seen gathering to roost in wetlands, particularly reedbeds.

How to identify

The swallow is a glossy, dark blue-black above and white below, with a dark red forehead and throat, and a black band across its chest. It has a very long, forked tail. Often spotted perching on wires in small numbers.

Distribution

Widespread.

Did you know?

Until the 19th century, people thought that the swallow hibernated over winter. Of course, we now know that it migrates to South Africa from the UK, undertaking a perilous journey, during which it is vulnerable to starvation and stormy weather.

Jai Ganesh · Dark Discussions at Cafe Infinity

Come Quotes - XVI

1. Pennies do not come from heaven. They have to be earned here on earth. - Margaret Thatcher

2. To explain all nature is too difficult a task for any one man or even for any one age. 'Tis much better to do a little with certainty & leave the rest for others that come after you. - Isaac Newton

3. Public education is our greatest pathway to opportunity in America. So we need to invest in and strengthen our public universities today, and for generations to come. - Michelle Obama

4. There is always the danger that we may just do the work for the sake of the work. This is where the respect and the love and the devotion come in - that we do it to God, to Christ, and that's why we try to do it as beautifully as possible. - Mother Teresa

5. The artist is a receptacle for emotions that come from all over the place: from the sky, from the earth, from a scrap of paper, from a passing shape, from a spider's web. - Pablo Picasso

6. The devil ain't got no power over me. The devil come, and me shake hands with the devil. Devil have his part to play. Devil's a good friend, too... because when you don't know him, that's the time he can mosh you down. - Bob Marley

7. All treaties between great states cease to be binding when they come in conflict with the struggle for existence. - Otto von Bismarck

8. I have become my own version of an optimist. If I can't make it through one door, I'll go through another door - or I'll make a door. Something terrific will come no matter how dark the present. - Rabindranath Tagore.

Jai Ganesh · Dark Discussions at Cafe Infinity

2444) Willis Lamb

Gist:

Work

According to Niels Bohr’s atomic model, a photon is emitted when an electron descends to a lower energy level. This results in a spectrum with lines corresponding to the different energy levels of different atoms. It appeared that the lines were divided into several lines close to one another, which Paul Dirac tried to explain in a theory. However, in 1947 Willis Lamb used precise measurements to establish what became known as the Lamb shift: what ought to have been a single energy level in the hydrogen atom according to Dirac’s theory actually was two nearby levels with a small difference in energy.

Summary

Willis Eugene Lamb, Jr. (born July 12, 1913, Los Angeles, Calif., U.S.—died May 15, 2008, Tucson, Ariz.) was an American physicist and corecipient, with Polykarp Kusch, of the 1955 Nobel Prize for Physics for experimental work that spurred refinements in the quantum theories of electromagnetic phenomena.

Lamb joined the faculty of Columbia University, New York City, in 1938 and worked in the Radiation Laboratory there during World War II. Though the quantum mechanics of P.A.M. Dirac had predicted the hyperfine structure of the lines that appear in the spectrum (dispersed light, as by a prism), Lamb applied new methods to measure the lines and in 1947 found their positions to be slightly different from what had been predicted. While a professor of physics (1951–56) at Stanford University, California, Lamb devised microwave techniques for examining the hyperfine structure of the spectral lines of helium. He was a professor of theoretical physics at the University of Oxford until 1962, when he was appointed a professor of physics at Yale University. In 1974 he became a professor of physics and optical sciences at the University of Arizona; he retired as professor emeritus in 2002.

Details

Willis Eugene Lamb Jr. (July 12, 1913 – May 15, 2008) was an American physicist who shared the 1955 Nobel Prize in Physics with Polykarp Kusch "for his discoveries concerning the fine structure of the hydrogen spectrum". Lamb was able to precisely determine a surprising shift in electron energies in a hydrogen atom, known as the Lamb shift. He was a professor at the University of Arizona College of Optical Sciences.

Biography

Lamb was born in Los Angeles, California, and attended Los Angeles High School. First admitted in 1930, he received a Bachelor of Science in chemistry from the University of California, Berkeley in 1934. For theoretical work on scattering of neutrons by a crystal, guided by J. Robert Oppenheimer, he received the Ph.D. in physics in 1938. Because of limited computational methods available at the time, this research narrowly missed revealing the Mössbauer Effect, 19 years before its recognition by Rudolf Mössbauer. He worked on nuclear theory, laser physics, and verifying quantum mechanics.

Lamb was a physics professor at Stanford from 1951 to 1956. He was the Wykeham Professor of Physics at the University of Oxford from 1956 to 1962, and also taught at Yale, Columbia and the University of Arizona. He was elected a Fellow of the American Academy of Arts and Sciences in 1963. In 2000, The Optical Society elected him an Honorary member.

Lamb is remembered as a "rare theorist turned experimentalist" by D. Kaiser.

Quantum physics

In addition to his crucial and famous contribution to quantum electrodynamics via the Lamb shift, in the latter part of his career he paid increasing attention to the field of quantum measurements. In one of his writings Lamb stated that "most people who use quantum mechanics have little need to know much about the interpretation of the subject." Lamb was also openly critical of many of the interpretational trends on quantum mechanics and of the use of the term photon.

Personal

In 1939 Lamb married his first wife, Ursula Schäfer, a German student, who became a distinguished historian of Latin America (and assumed his last name). After her death in 1996, he married physicist Bruria Kaufman in 1996, whom he later divorced. In 2008 he married Elsie Wattson.

Lamb died on May 15, 2008, at the age of 94, due to complications of a gallstone disorder.

Jai Ganesh · This is Cool

Gist

Cardiac catheterization is a minimally invasive procedure where a thin, flexible tube (catheter) is inserted into a blood vessel in the groin, arm, or neck and guided to the heart to diagnose or treat conditions like clogged arteries, valve issues, or arrhythmia. It allows doctors to measure pressures, take samples, perform angioplasty, and place stents.

In cardiac catheterization (or cath), your healthcare provider puts a very small, flexible, hollow tube (catheter) into a blood vessel in the groin, arm, wrist, or in rare cases the neck. Then your provider threads it through the blood vessel into the aorta and into the heart.

Summary

Cardiac catheterization, also known as cardiac cath or heart catheterization, is a medical procedure used to diagnose and treat some heart conditions. It lets doctors take a close look at the heart to identify problems and to perform other tests or procedures.

Your healthcare provider may recommend cardiac catheterization to find out the cause of symptoms such as chest pain or irregular heartbeat. Before the procedure, you may need to diagnostic tests, such as blood tests, heart imaging tests, or a stress test, to determine how well your heart is working and to help guide the procedure.

During cardiac catheterization, a long, thin, flexible tube called a catheter is put into a blood vessel in your arm, groin or upper thigh, or neck. The catheter is then threaded through the blood vessels to your heart. It may be used to examine your heart valves or take samples of blood or heart muscle. Your doctor may also use ultrasound, a test that uses sound waves to create an image, or they may inject a dye into your coronary arteries to see whether your arteries are narrowed or blocked. Cardiac catheterization may also be used instead of some heart surgeries to repair heart defects and replace heart valves.

Cardiac catheterization is safe for most people. Problems following the procedure are rare but can include bleeding and blood clots. Your healthcare provider will monitor your condition and may recommend medicines to prevent blood clots.

Details

Cardiac catheterization (heart cath) is the insertion of a catheter into a chamber or vessel of the heart. This is done both for diagnostic and interventional purposes.

A common example of cardiac catheterization is coronary catheterization that involves catheterization of the coronary arteries for coronary artery disease and myocardial infarctions ("heart attacks"). Catheterization is most often performed in special laboratories with fluoroscopy and highly maneuverable tables. These "cath labs" are often equipped with cabinets of catheters, stents, balloons, etc. of various sizes to increase efficiency. Monitors show the fluoroscopy imaging, electrocardiogram (ECG), pressure waves, and more.

Procedure

"Cardiac catheterization" is a general term for a group of procedures. Access to the heart is obtained through a peripheral artery or vein. Commonly, this includes the radial artery, internal jugular vein, and femoral artery/vein. Each blood vessel has its advantages and disadvantages. Once access is obtained, plastic catheters (tiny hollow tubes) and flexible wires are used to navigate to and around the heart. Catheters come in numerous shapes, lengths, diameters, number of lumens, and other special features such as electrodes and balloons. Once in place, they are used to measure or intervene. Imaging is an important aspect to catheterization and commonly includes fluoroscopy but can also include forms of echocardiography (TTE, TEE, ICE) and ultrasound (IVUS).

TTE: Transthoracic echocardiogram
TEE: Transesophageal echocardiogram
ICE: Intracardiac echocardiogram
UVUS : Intravascular ultrasound

Obtaining access uses the Seldinger technique by puncturing the vessel with a needle, placing a wire through the needle into the lumen of the vessel, and then exchanging the needle for a larger plastic sheath. Finding the vessel with a needle can be challenging and both ultrasound and fluoroscopy can be used to aid in finding and confirming access. Sheaths typically have a side port that can be used to withdraw blood or inject fluids/medications, and they also have an end hole that permits introducing the catheters, wires, etc. coaxially into the blood vessel.

Once access is obtained, what is introduced into the vessel depends on the procedure being performed. Some catheters are formed to a particular shape and can really only be manipulated by inserting/withdrawing the catheter in the sheath and rotating the catheter. Others may include internal structures that permit internal manipulation (e.g., intracardiac echocardiography).

Finally, when the procedure is completed, the catheters are removed and the sheath is removed. With time, the hole made in the blood vessel will heal. Vascular closure devices can be used to speed along hemostasis.

Equipment

Much equipment is required for a facility to perform the numerous possible procedures for cardiac catheterization.

General:

* Catheters
* Film or Digital Camera
* Electrocardiography monitors
* External defibrillator
* Fluoroscopy
* Pressure transducers
* Sheaths

Percutaneous coronary intervention:

* Coronary stents: bare-metal stent (BMS) and drug-eluting stent (DES)
* Angioplasty balloons
* Atherectomy lasers and rotational devices
* Left atrial appendage occlusion devices

Electrophysiology:

* Ablation catheters: radiofrequency (RF) and cryo
* Pacemakers
* Defibrillators

Additional Information:

What is cardiac catheterization?

In cardiac catheterization (or cath), your healthcare provider puts a very small, flexible, hollow tube (catheter) into a blood vessel in the groin, arm, wrist, or in rare cases the neck. Then your provider threads it through the blood vessel into the aorta and into the heart. Once the catheter is in place, several tests may be done. Your provider can place the tip of the catheter into various parts of the heart to measure the pressures in the heart chambers. Or they can take blood samples to measure oxygen levels.

Your healthcare provider can guide the catheter into the coronary arteries and inject contrast dye to check blood flow through them. The coronary arteries are the vessels that carry blood to the heart muscle. This is called coronary angiography.

These are some of the other procedures that may be done during or after a cardiac cath:

* Angioplasty. In this procedure, your healthcare provider can inflate a tiny balloon at the tip of the catheter. This presses any plaque buildup against the artery wall and improves blood flow through the artery.

* Stent placement. In this procedure, your provider expands a tiny metal mesh coil or tube at the end of the catheter inside an artery to keep it open.

* Fractional flow reserve. This is a pressure management method that’s used in catheterization to see how much blockage is in an artery.

* Intravascular ultrasound (IVUS). This test uses a computer and a transducer to send out ultrasonic sound waves to make images of the blood vessels. By using IVUS, your healthcare provider can see and measure the inside of the blood vessels.

* Biopsy. Your provider may take out a small tissue sample and examine it under the microscope for abnormalities.

During the procedure, you will be awake. But a small amount of sedating medicine will be given before starting to help keep you comfortable.

Why might I need cardiac catheterization?

Your healthcare provider may use cardiac cath to help diagnosis these heart conditions:

* Atherosclerosis. This is a gradual clogging of the arteries by fatty materials and other substances in the blood stream.

* Cardiomyopathy. This is an enlargement of the heart due to thickening or weakening of the heart muscle

* Congenital heart disease. Defects in 1 or more heart structures that occur during fetal development, such as a ventricular septal defect (hole in the wall between the 2 lower chambers of the heart), are called congenital heart defects. This may lead to abnormal blood flow within the heart.

* Heart failure. This condition is when the heart muscle has become too weak to pump blood well. It causes fluid buildup (congestion) in the blood vessels and lungs, and edema (swelling) in the feet, ankles, and other parts of the body.

* Heart valve disease. This is when 1 or more of the heart valves isn't working right, affecting blood flow within the heart.

* Rejection after heart transplant. A biopsy is a common procedure after a heart transplant to monitor for rejection. Rejection is a process of your body's immune system attacking the donor heart. Medicines must be taken life-long following a transplant to prevent rejection.

You may have a cardiac cath if you have recently had 1 or more of these symptoms:

* Chest pain (angina)

* Shortness of breath

* Dizziness

* Extreme tiredness

If a screening exam, such as an electrocardiogram (ECG) or stress test, suggests there may be a heart condition that needs to be explored further, your healthcare provider may order a cardiac cath.

Another reason for a cath procedure is to evaluate blood flow to the heart muscle if chest pain occurs after the following:

* Heart attack

* Coronary artery bypass surgery

* Coronary angioplasty. This is opening a coronary artery using a balloon or other method.

* Placement of a stent. A stent is a tiny metal coil or tube placed inside an artery to keep the artery open.

There may be other reasons for your healthcare provider to recommend a cardiac cath.

What are the risks of cardiac catheterization?

Possible risks of cardiac cath include:

* Bleeding or bruising where the catheter is put into the body (the groin, arm, neck, or wrist)

* Pain where the catheter is put into the body

* Blood clot or damage to the blood vessel that the catheter is put into

* Infection where the catheter is put into the body

* Problems with heart rhythm (usually temporary)

More serious but rare complications include:

* Less blood flow to the heart tissue (ischemia), chest pain, or heart attack

* Sudden blockage of a coronary artery

* A tear in the lining of an artery

* Kidney damage from the dye used

* Bleeding from the heart itself

* Stroke

* Need for heart surgery

If you are pregnant or think you could be, tell your healthcare provider. There is a risk of injury to the unborn baby from a cardiac cath. Radiation exposure during pregnancy may lead to birth defects. Also be sure to tell your provider if you are lactating or breastfeeding.

There is a risk for allergic reaction to the dye used during the cardiac cath. If you are allergic to or sensitive to medicines, contrast dye, iodine, or latex, tell your healthcare provider. Also, tell them if you have kidney failure or other kidney problems.

For some people, having to lie still on the cardiac cath table for the length of the procedure may cause some discomfort or pain.

There may be other risks depending on your specific health problem. Be sure to talk about any concerns with your healthcare provider before the procedure.

How do I get ready for cardiac catheterization?

* Your healthcare provider will explain the procedure to you and give you a chance to ask any questions.

* You will be asked to sign a consent form that gives your permission to do the test. Read the form carefully and ask questions if anything is unclear.

* Tell your healthcare provider if you have ever had a reaction to any contrast dye, if you are allergic to iodine, or if you are sensitive to or are allergic to any medicines, latex, tape, and anesthetic agents (local and general).

* You will need to fast (not eat or drink) for a certain period before the procedure. Your provider will tell you how long to fast, usually overnight.

* If you are pregnant or think you could be, tell your provider.

* Tell your provider if you have any body piercings on your chest or belly (abdomen).

* Tell your provider about all the medicines (prescription and over-the-counter), vitamins, herbs, and supplements that you are taking.

* You may be asked to stop certain medicines before the procedure. Your provider will give you detailed instructions.

* Let your provider know if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medicines, aspirin, or other medicines that affect blood clotting. You may need to stop some of these medicines before the procedure.

* Let you provider know if you have any kidney problems. The contrast dye used during the cardiac cath can cause kidney damage in people who have poor kidney function. In some cases, blood tests may be done before and after the test to be sure that your kidneys are working correctly.

* Your provider may request a blood test before the procedure to see how long it takes your blood to clot. Other blood tests may be done as well.

* Tell your provider if you have heart valve disease.

* Tell your provider if you have a pacemaker or any other implanted cardiac devices.

* You may get a sedative before the procedure to help you relax. If a sedative is used, you will need someone to drive you home afterward.

Based on your medical condition, your healthcare provider may request other specific preparations.

What happens during a cardiac catheterization?

A cardiac cath can be done on an outpatient basis or as part of your stay in a hospital. Procedures may vary depending on your condition and your healthcare provider's practices.

Generally, a cardiac cath follows this process:

* You'll remove any jewelry or other objects that may interfere with the procedure. You may wear your dentures or hearing aids if you use either of these.

* Before the procedure, you should empty your bladder then change into a hospital gown.

* A healthcare provider may shave the area where the catheter will be put in. The catheter is most often put in at the groin area. But other places used are the wrist, inside the elbow, or the neck.

* A healthcare provider will start an IV (intravenous) line in your hand or arm before the procedure to give you IV fluids and medicines, if needed.

* You will lie on your back on the procedure table.

* You will be connected to an ECG monitor that records the electrical activity of your heart and keeps track of your heart during the procedure using small electrodes that stick to your skin. Your vital signs (heart rate, blood pressure, breathing rate, and oxygen level) will be tracked during the procedure.

* Several monitor screens in the room will show your vital signs, the images of the catheter being moved through your body into your heart, and the structures of your heart as the dye is injected.

* You will get a sedative in your IV line before the procedure to help you relax. But you will likely be awake during the procedure.

* Your pulses below the catheter insertion site will be checked and marked so that the circulation to the limb can be checked after the procedure.

* Your healthcare provider will inject a local anesthetic (numbing medicine) into the skin where the catheter will be put in. You may feel some stinging at the site for a few seconds after the local anesthetic is injected.

* Once the local anesthetic has taken effect, your healthcare provider inserts a sheath, or introducer, into the blood vessel. This is a plastic tube through which the catheter is thread into the blood vessel and advanced into the heart. If the arm is used, your provider may make a small incision (cut) to expose the blood vessel and put in the sheath.

* Your healthcare provider will advance the catheter through the aorta to the left side of the heart. They may ask you to hold your breath, cough, or move your head a bit to get clear views and advance the catheter. You may be able to watch this process on a computer screen.

* Once the catheter is in place, your provider will inject contrast dye to visualize the heart and the coronary arteries. You may feel some effects when the contrast dye is injected into the catheter. These effects may include a flushing sensation, a salty or metallic taste in the mouth, nausea, or a brief headache. These effects usually last for only a few moments.

* Tell the provider if you feel any breathing difficulties, sweating, numbness, nausea or vomiting, chills, itching, or heart palpitations.

* After the contrast dye is injected, a series of rapid X-ray images of the heart and coronary arteries will be made. You may be asked to take a deep breath and hold it for a few seconds during this time. It’s important to be very still as the X-rays are taken.

* Once the procedure is done, your provider will remove the catheter and close the insertion site. They may close it using either collagen to seal the opening in the artery, sutures, a clip to bind the artery together, or by holding pressure over the area to keep the blood vessel from bleeding. Your provider will decide which method is best for you.

* If a closure device is used, a sterile dressing will be put over the site. If manual pressure is used, your healthcare provider (or an assistant) will hold pressure on the site so that a clot will form. Once the bleeding has stopped, a very tight bandage will be placed on the site.

* The staff will help you slide from the table onto a stretcher so that you can be taken to the recovery area. Note: If the catheter was placed in your groin, you will not be allowed to bend your leg for several hours. If the insertion site was in your arm, your arm will be elevated on pillows and kept straight by placing it in an arm guard (a plastic arm board designed to immobilize the elbow joint). In addition, a tight plastic band may be put around your arm near the insertion site. The band will be loosened over time and removed before you go home.

What happens after cardiac catheterization?

* In the hospital:

After the cardiac cath, you may be taken to a recovery room or returned to your hospital room. You will stay flat in bed for several hours. A nurse will keep track of your vital signs, the insertion site, and circulation in the affected leg or arm.

Let your nurse know right away if you feel any chest pain or tightness, or any other pain, as well as any feelings of warmth, bleeding, or pain at the insertion site.

Bedrest may vary from 4 to 6 hours. If your healthcare provider placed a closure device, your bedrest may be shorter.

In some cases, the sheath or introducer may be left in the insertion site. If so, you will be on bedrest until your provider or another team member removes the sheath. After the sheath is removed, you may be given a light meal.

You may feel the urge to urinate often because of the effects of the contrast dye and increased fluids. You will need to use a bedpan or urinal while on bedrest, so you don't bend the affected leg or arm.

After the period of bed rest, you may get out of bed. The nurse will help you the first time you get up. They may check your blood pressure while you are lying in bed, sitting, and standing. You should move slowly when getting up from the bed to prevent any dizziness from the long period of bed rest.

You may be given medicine for pain or discomfort related to the insertion site or having to lie flat and still for a prolonged period.

Drink plenty of water and other fluids to help flush the contrast dye from your body.

You may go back to your usual diet after the procedure, unless your healthcare provider tells you otherwise.

After the recovery period, you may be discharged home unless your healthcare provider decides otherwise. In many cases, you may spend the night in the hospital for careful observation. If the cardiac cath was done on an outpatient basis and a sedative was used, you must have another person drive you home.

* At home

Once at home, you should check the insertion site for bleeding, unusual pain, swelling, and abnormal discoloration or temperature change. A small bruise is normal. If you notice a constant or large amount of blood at the site that cannot be contained with a small dressing, contact your healthcare provider.

If your healthcare provider used a closure device at your insertion site, you will be given instructions on how to take care of the site. There may be a small knot, or lump, under the skin at the site. This is normal. The knot should go away over a few weeks.

It will be important to keep the insertion site clean and dry. Your healthcare provider will give you specific bathing instructions. In general, don't soak the access site in water (no bathtubs, hot tubs, or swimming) until the skin is healed at the site.

Your healthcare provider may advise you not to do any strenuous activities for a few days after the procedure. They'll tell you when it's OK to go back to work, drive, and resume normal activities.

Contact your healthcare provider if you have any of the following:

* Fever or chills

* Increased pain, redness, swelling, or bleeding or other drainage from the insertion site

* Coolness, numbness or tingling, or other changes in the affected arm or leg

* Chest pain or pressure, nausea or vomiting, profuse sweating, dizziness, or fainting

Your healthcare provider may give you other instructions after the procedure, depending on your situation.

Next steps

Before you agree to the test or procedure, make sure you know:

* The name of the test or procedure

* The reason you are having the test or procedure

* What results to expect and what they mean

* The risks and benefits of the test or procedure

* What the possible side effects or complications are

* When and where you are to have the test or procedure

* Who will do the test or procedure and what that person’s qualifications are

* What would happen if you did not have the test or procedure

* Any alternative tests or procedures to think about

* When and how you will get the results

* Who to call after the test or procedure if you have questions or problems

* How much you will have to pay for the test or procedure

Jai Ganesh · Science HQ

Pyrometer

Gist

A pyrometer is a non-contact device designed to measure high surface temperatures, typically above 500°C , by detecting infrared radiation emitted from an object. Ideal for industrial applications (e.g., smelting, glass manufacturing), these tools provide fast, accurate measurements for moving, inaccessible, or extremely hot materials.

A pyrometer is used for non-contact temperature measurement, particularly for very high temperatures (often above 500°C) or for objects that are too hot, far away, or difficult to reach with traditional thermometers, by detecting the thermal radiation (infrared) they emit. They are essential in industries like steel, glass, and electronics for monitoring furnaces, molten materials, and manufacturing processes where accuracy and safety are critical, ensuring consistent heat distribution.

Summary

A pyrometer is a device for measuring relatively high temperatures, such as are encountered in furnaces. Most pyrometers work by measuring radiation from the body whose temperature is to be measured. Radiation devices have the advantage of not having to touch the material being measured. Optical pyrometers, for example, measure the temperature of incandescent bodies by comparing them visually with a calibrated incandescent filament that can be adjusted in temperature. In an elementary radiation pyrometer, the radiation from the hot object is focused onto a thermopile, a collection of thermocouples, which generates an electrical voltage that depends on the intercepted radiation. Proper calibration permits this electrical voltage to be converted to the temperature of the hot object.

In resistance pyrometers a fine wire is put in contact with the object. The instrument converts the change in electrical resistance caused by heat to a reading of the temperature of the object. Thermocouple pyrometers measure the output of a thermocouple (q.v.) placed in contact with the hot body; by proper calibration, this output yields temperature. Pyrometers are closely akin to the bolometer and the thermistor and are used in thermometry.

Details

A pyrometer, or radiation thermometer, is a type of remote sensing thermometer used to measure the temperature of distant objects. Various forms of pyrometers have historically existed. In the modern usage, it is a device that from a distance determines the temperature of a surface from the amount of the thermal radiation it emits, a process known as pyrometry, a type of radiometry.

The word pyrometer comes from the Greek word for fire, (pyr), and meter, meaning to measure. The word pyrometer was originally coined to denote a device capable of measuring the temperature of an object by its incandescence, visible light emitted by a body which is at least red-hot. Infrared thermometers, can also measure the temperature of cooler objects, down to room temperature, by detecting their infrared radiation flux. Modern pyrometers are available for a wide range of wavelengths and are generally called radiation thermometers.

Principle

A pyrometer is based on the principle that the intensity of light received by the observer depends upon the distance of the observer from the source and the temperature of the distant source. A modern pyrometer has an optical system and a detector. The optical system focuses the thermal radiation onto the detector. The output signal of the detector (temperature T) is related to the thermal radiation of the target object through the Stefan–Boltzmann law.

This output is used to infer the object's temperature from a distance, with no need for the pyrometer to be in thermal contact with the object; most other thermometers (e.g. thermocouples and resistance temperature detectors (RTDs)) are placed in thermal contact with the object and allowed to reach thermal equilibrium.

Pyrometry of gases presents difficulties. These are most commonly overcome by using thin-filament pyrometry or soot pyrometry. Both techniques involve small solids in contact with hot gases.

Applications

Pyrometers are suited especially to the measurement of moving objects or any surfaces that cannot be reached or cannot be touched. Contemporary multispectral pyrometers are suitable for measuring high temperatures inside combustion chambers of gas turbine engines with high accuracy.

Temperature is a fundamental parameter in metallurgical furnace operations. Reliable and continuous measurement of the metal temperature is essential for effective control of the operation. Smelting rates can be maximized, slag can be produced at the optimal temperature, fuel consumption is minimized and refractory life may also be lengthened. Thermocouples were the conventionally used for this purpose, but they are unsuitable for continuous measurement because they melt and degrade.

Salt bath furnaces operate at temperatures up to 1300 °C and are used for heat treatment. At very high working temperatures with intense heat transfer between molten salt and the steel being treated, precision is maintained by measuring the temperature of the molten salt. Most errors are caused by slag on the surface, which is cooler than the salt bath.

The tuyère pyrometer is an optical instrument for temperature measurement through the tuyères, which are normally used for feeding air or reactants into the bath of the furnace.

A steam boiler may be fitted with a pyrometer to measure the steam temperature in the superheater.

A hot air balloon is equipped with a pyrometer for measuring the temperature at the top of the envelope in order to prevent overheating of the fabric.

Pyrometers may be fitted to experimental gas turbine engines to measure the surface temperature of turbine blades. Such pyrometers can be paired with a tachometer to tie the pyrometer output with the position of an individual turbine blade. Timing combined with a radial position encoder allows engineers to determine the temperature at precise points on blades moving past the probe.

Additional Information

A pyrometer is a precision instrument designed to measure temperature from a distance by detecting infrared (IR) radiation. This contact-free method is critical for monitoring heat-intensive processes in various industries, including those involving molten metals, ceramics, and high-speed production lines.

Pyrometers work by detecting infrared (IR) radiation. A pyrometer is an optical device that uses a lens to focus the IR radiation onto a detector, which converts the IR radiation into an electrical signal. The temperature of the object can then be calculated from the strength of the IR radiation that is detected.

IR radiation refers to a specific part of the electromagnetic spectrum that is not visible to the naked eye. All objects with a temperature, including cold objects, emit IR radiation, but as an object’s temperature increases, so does the amount of IR radiation that it emits, so it is often referred to as “heat radiation”.

How Does a Pyrometer Determine a Temperature from IR?

To measure temperature with a pyrometer, the device must first be calibrated to a known temperature. This is typically done using a blackbody calibration source, a device that emits a known amount of IR radiation at specific temperatures.

The pyrometer uses a detector to measure the amount of IR radiation emitted by the object. The detector converts the IR radiation into an electrical signal, which is then processed by the pyrometer’s electronics to calculate the temperature of the object.

The temperature calculation is based on the principle that the amount of IR radiation emitted by an object is directly proportional to its temperature. Therefore, the more IR radiation that the pyrometer detects, the higher the object’s temperature. The pyrometer can then display the temperature of the object on its screen or output the temperature to a computer or other device.

What Can Interfere with the Accuracy of a Pyrometer?

It’s important to be aware of possible sources of interference that might cause a temperature reading error when using a pyrometer, for example:

* Other sources of IR radiation: IR radiation from another hot object nearby could influence the measurement if it can be picked up by the pyrometer’s field of view.
* Transparent materials: If a transparent material is being measured, hot objects behind the measured object might cause interference.
* Dust, steam, vapour, smoke, etc.: These can all attenuate IR radiation, leading to inaccurate measurements.
* Field of view errors: The spot has to fit the size of the object if a single-colour pyrometer is being used.
* Electromagnetic interference: Strong electromagnetic fields can interfere with a pyrometer’s electronics.

With careful consideration and the correct selection of the pyrometer, most of these potential sources of interference can be avoided.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#10771. What does the term Defile (geography) mean?

#10772. What does the term in Geography Deforestation mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#5967. What does the noun megaplex mean?

#5968. What does the noun melanoma mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2580. What does the medical term Pericardium mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9866.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6359.

Jai Ganesh · Exercises

Hi,

2720.

Jai Ganesh · This is Cool

2506) Mountain Lion

Mountain Lion

Gist

Mountain lions are known by many names, including cougar, puma, catamount, painter, panther, and many more. They are the most wide-ranging cat species in the world and are found as far north as Canada and as far south as Chile.

The puma (Puma concolor) is a large cat belonging to the felidae family. It is similar in size to the jaguar, and is found is a wide variety of habitats throughout the Americas. It is also known as the cougar, mountain lion and a number of other names.

Summary

The cougar (Puma concolor), also called puma, mountain lion, catamount, and panther, is a large small cat native to the Americas. It inhabits North, Central and South America, making it the most widely distributed wild, terrestrial mammal in the Western Hemisphere, and one of the most widespread in the world. Its range spans Yukon, British Columbia and Alberta in Canada, the Rocky Mountains and areas in the western United States. Further south, its range extends through Mexico to the Amazon rainforest and the southern Andes Mountains in Patagonia. It is an adaptable generalist species, occurring in most American habitat types. It prefers habitats with dense underbrush and rocky areas for stalking but also lives in open areas.

The cougar is largely solitary. Its activity pattern varies from diurnality and cathemerality to crepuscularity and nocturnality between protected and non-protected areas, and is apparently correlated with the presence of other predators, prey species, livestock and humans. It is an ambush predator that pursues a wide variety of prey. Ungulates, particularly deer, are its primary prey, but it also hunts rodents. It is territorial and lives at low population densities. Individual home ranges depend on terrain, vegetation and abundance of prey. While large, it is not always the dominant apex predator in its range, yielding prey to other predators. It is reclusive and mostly avoids people. Fatal attacks on humans are rare but increased in North America as more people entered cougar habitat and built farms.

The cougar is listed as Least Concern on the IUCN Red List. Intensive hunting following European colonization of the Americas and ongoing human development into cougar habitat has caused populations to decline in most parts of its historical range. In particular, the eastern cougar population is considered to be mostly locally extinct in eastern North America since the early 20th century, with the exception of the isolated Florida panther subpopulation.

Details

The cougar is a cat of many names: Puma, mountain lion, and catamount, among others.

This adaptable predator has the widest range of any land mammal in the Western Hemisphere, and can be found in many habitats throughout the Americas, from Florida swamps to Canadian forests. In some areas, such as heavily urbanized southern California, cougars are increasingly sharing space with people.

Cougars are the world’s fourth largest wildcat after lions, tigers, and jaguars. They are stocky with large hind legs and a long tail—about a third of their length—which provides balance. Their strong back legs enable them to leap around 40 feet horizontally, or 18 feet vertically in a single jump.

Their scientific name—Puma concolor, which means “of one color” in Latin—refers to their evenly colored coat: usually a solid orange, yellow, tan, rusty brown, or gray with a white belly. In rare cases, cougars can be white, but no cases of black, or melanistic, cougars have ever been documented.

Hunting habits

Cougars hunt at dawn and dusk. They usually prey on deer, although these opportunistic predators also eat coyotes, moose, wild sheep, birds, and rodents. They even kill feral donkeys, an invasive species in California’s Death Valley National Park.

The cats silently stalk their prey, then pounce and kill them with a fatal bite to the back of the head or neck. When dealing with a large carcass, a cougar will eat as much as it can before hiding the rest to come back to later.

Harmful encounters with people are rare: Between 1924 and 2018, 74 cougar attacks—including 11 fatalities—were documented in 10 U.S. states.

Reproduction

Male cougars maintain large territories that overlap with several smaller territories of their mates. About three months after mating, a female gives birth to three or four kittens in a secluded den, where she stays for 10 days. Babies are born with camouflaged, spotted coats that fade into a solid color as they grow.

After six weeks, the family will leave the den, and kittens learn to hunt from their mother. Cougars are ready to set out on their own at around 18 months old. Males often strike out farther from their mother to avoid the threats of a rival male; one was recorded traveling 1,800 miles in search of a new home.

Hollywood cougar

Arguably the world’s most famous cougar was an animal called P-22, whose father was P-001—the first puma to be collared by the National Park Service. Born in the Santa Monica Mountains, P-22 left his birthplace to find his own territory and crossed some of the world’s busiest freeways to reach L.A.’s Griffith Park, part of the Hollywood Hills, where he lived for 10 years.

P-22 was compassionately euthanized in December 2022 when he was caught for an evaluation, which showed he was underweight, had organ failure, and was likely hit by a car.

Threats to survival

Cougars once roamed nearly all of the United States, but by the early 1900s, they were mostly hunted to extinction in the Midwest and eastern U.S. The Florida panther—a subspecies only found in Florida—survived, though today fewer than 200 individuals remain in the wild.

Overall, cougar populations are stable, and the International Union for the Conservation of Nature's Red List categorizes them as a species of least concern.

Yet throughout their wide range, the felines are threatened by poisonings from various substances, vehicle collisions, retaliatory killings, and hunting. (Learn more about cougars, also called ghost cats.)

Habitat fragmentation is also a pressing problem. Unlike P-22, most cougars can’t cross sprawling freeways, and this lack of connectivity causes low genetic diversity and inbreeding.

That’s why, in southern California, the Wallis Annenberg Wildlife Crossing will help various wildlife species safely cross U.S. Highway 101.

Additional Information

What's in a name? Mountain lion, puma, cougar, panther—these cats are known by more names than just about any other mammal! But no matter what you call them, they're still the same cat, Puma concolor, the largest of the "small cats." So why do we call them so many different names? Mostly because they have such a large range, and people from different countries have called them different things.

Early Spanish explorers of North and South America called them leon (lion) and gato monte (cat of the mountain), from which we get the name "mountain lion." “Puma” is the name the Incas gave these cats in their language. “Cougar” seems to have come from an old South American Indian word, cuguacuarana, which was shortened to "cuguar" and then spelled differently. And “panther” is a general term for cats that have solid-colored coats, so it was used for black pumas as well as black jaguars and black leopards. All of these names are considered correct, but in Southern California we most commonly call them mountain lions.

You may have heard of Florida panthers. They are a subspecies of mountain lion that used to be found from Texas throughout the southeast but now only live in southern Florida’s swamps. They are Endangered, with only about 200 cats left, and conservation efforts are underway to save them.

Mountain lions are generally a solid tawny color, with slightly darker hair on their back and a whitish underside. Those living in warm, humid areas tend to be a darker, reddish-brown color, and mountain lions found in colder climates have thicker, longer hair that is almost silver-gray in color. Adult males weigh 40 to 60 percent more than adult females. Scientists classify mountain lions as small cats, as they do not roar, but purr like smaller cats do. Their slender bodies and calm demeanor are more like that of a cheetah; both cats would rather flee than fight, and both rarely confront people.

Habitat and Diet

Besides people, mountain lions have the largest range of any terrestrial mammal in the Western hemisphere, from northern British Columbia to Argentina. They live in a variety of habitats, at home in forests, prairies, deserts, and swamps—they are very adaptable cats! Mountain lions are solitary, except during breeding or when a mother is caring for her cubs. But that doesn’t mean they don’t have any contact with one another.

Mountain lions live in home ranges that vary in size from 30 to 125 square miles (7,770 to 32,375 hectares). These ranges overlap, so cats share some parts. The home range of males tends to be largest and overlap the smaller ranges of several females. Mountain lions find shelter to rest or escape from bad weather in thick brush, rocky crevices, or caves, which might be anywhere in their home range.

Although cats may see each other occasionally, they mostly leave "messages," with feces, urine, scratched logs, or marks they scrape out in the dirt or snow. Mountain lions can also growl, hiss, mew, yowl, squeak, spit, and purr to get their message across to other cats, and they are known for a short, high-pitched scream and a whistle-like call.

Mountain lions are powerfully built, with large paws and sharp claws. Their hind legs are larger and more muscular than their front legs, which gives them great jumping power. They can run fast and have a flexible spine like a cheetah’s to help them maneuver around obstacles and change direction quickly.

Even so, mountain lions are mostly ambush hunters, launching at prey to knock it off balance. They have especially keen eyesight, and they usually find prey by seeing it move. These cats may be on the prowl during the day or at night, but they are most active at dusk and dawn.

Mountain lions hunt over a large area, and it can take a week for one to travel all the way around its home range. They eat a variety of prey depending on where they live, including deer, pigs, capybaras, raccoons, armadillos, hares, and squirrels. Some larger cats even bring down prey as big as an elk or a moose. But hunting large prey brings risk, and many mountain lions suffer life-threatening injuries received from a hunt, especially from a prey’s sharp horns, antlers, or hooves. Mountain lions often bury part of their kill to save for a later meal, hiding the food with leaves, grass, dirt, or even snow, depending on the habitat and time of year.

Family Life

A female ready to breed alerts any males in the area by calling and rubbing her scent on rocks and trees. A male may stay with a female for several days before looking for his next mate. An expectant mother sets up a den where she gives birth to one to six cubs. The newborns have spots, which may help them blend in with grass, brush, and dappled sunlight. Their mother nurses them for three months or so, but they can eat meat at about six weeks of age. At six months old, their spots begin to fade, and they learn to hunt. They continue to live with their mother until they're 12 to 18 months old.

Conservation

As more people have moved into mountain lion territory, the number of encounters with them has increased. This is often "big news" and frightens people. But overall, meeting a mountain lion is an unlikely event. Mountain lions don’t want to confront people, and they do their best to avoid us. You can avoid them, too, by not hiking alone, or at dusk and dawn when mountain lions are hunting. Make noise as you hike, and don’t leave food out around a cabin or campsite, especially at night. If you do happen across a mountain lion, never approach it—always keep a respectful distance.

When Europeans first settled in North America, mountain lions lived from coast to coast. But they soon came to be viewed as threats to livestock. By the 1940s, many states, including California, placed a bounty on mountain lions. Due in major part to the bounty system, mountain lions are now confined to the West, except for a small population in Florida. Some people continue to hunt them despite legal protections.

Mountain lions have an essential role to play in our ecosystem. They are one of the top predators, and without them, populations of deer and herbivores would become unhealthy and too large for the habitat. It’s true that mountain lions can be dangerous, and coexistence challenges should be reported to state or local wildlife organizations. But people like to live and play in or near natural habitats, so we need to understand and respect the wildlife that live there. If we take responsibility for our own actions, pets, livestock, and property, we can learn to peacefully coexist with mountain lions and appreciate their power and grace.

While globally mountain lion populations are stable, they still face threats like habitat loss and fragmentation, poaching of their prey, and retaliatory hunting. In California, mountain lions are classified as a specially protected mammal.

Jai Ganesh · Dark Discussions at Cafe Infinity

2443) Dickinson W. Richards

Gist:

Life

Dickinson Richards was born in New Jersey, the son of a lawyer. After liberal arts studies at Yale University, Richards studied medicine at Columbia University in New York, becoming a medical doctor in 1923. Following work at Presbyterian Hospital in New York and elsewhere, in 1931 he began a prolonged collaboration with André Cournand at Bellevue Hospital and Columbia University. Richards was married and had four children.

Work

Even though Werner Forssmann succeeded in inserting a catheter into his own heart in 1929, there was great hesitance about continuing this type of research. Nonetheless, beginning in 1941 Dickinson Richards and André Cournand published a series of studies that established use of cardiac catheterization, among other things, to introduce contrast fluid for X-ray images and to measure pressure and oxygen content. Because it was possible to reach the upper chambers of the heart, blood pressure and the blood’s oxygen content could be measured on the way from the heart to the lungs, which was impossible before.

Summary

Dickinson Woodruff Richards (born Oct. 30, 1895, Orange, N.J., U.S.—died Feb. 23, 1973, Lakeville, Conn.) was an American physiologist who shared the Nobel Prize for Physiology or Medicine in 1956 with Werner Forssmann and André F. Cournand. Cournand and Richards adapted Forssmann’s technique of using a flexible tube (catheter), conducted from an elbow vein to the heart, as a probe to investigate the heart.

Richards received an A.B. degree from Yale University in 1917 and later studied at Columbia University’s College of Physicians and Surgeons (M.A., 1922; M.D., 1923). After a hospital internship and a brief study in England, he returned to Columbia University in 1928 and taught there from 1947 to 1961. From 1945 to 1961 he worked at Bellevue Hospital, New York City, where he met Cournand. Their use and perfection of Forssmann’s method, known as cardiac catheterization, permitted them to measure blood pressure and other conditions inside the heart.

Details

Dickinson Woodruff Richards Jr. (October 30, 1895 – February 23, 1973) was an American physician and physiologist. He was a co-recipient of the Nobel Prize in Physiology or Medicine in 1956 with André Cournand and Werner Forssmann for the development of cardiac catheterization and the characterisation of a number of cardiac diseases.

Early life

Richards was born in Orange, New Jersey. He was educated at the Hotchkiss School in Connecticut, and entered Yale University in 1913. At Yale he studied English and Greek, graduating in 1917 as a member of the senior society Scroll and Key.

Career

He joined the United States Army in 1917, and became an artillery instructor. He served from 1918 to 1919 as an artillery officer in France.

When he returned to the United States, Richards attended Columbia University College of Physicians and Surgeons, graduating with an M.A. in 1922 and his M.D. degree in 1923. He was on the staff of the Presbyterian Hospital in New York until 1927, when he went to England to work at the National Institute for Medical Research in London, under Sir Henry Dale, on the control of circulation in the liver.

In 1928, Richards returned to the Presbyterian Hospital and began his research on pulmonary and circulatory physiology, working under Professor Lawrence Henderson of Harvard. He began collaborations with André Cournand at Bellevue Hospital, New York, working on pulmonary function. Initially their research focussed on methods to study pulmonary function in patients with pulmonary disease.

Their next area of research was the development of a technique for catheterization of the heart. Using this technique they were able to study and characterise traumatic shock, the physiology of heart failure. They measured the effects of cardiac drugs and described various forms of dysfunction in chronic cardiac diseases and pulmonary diseases and their treatment, and developed techniques for the diagnosis of congenital heart diseases. For this work, Richards, Cournand, and Werner Forssmann were awarded the Nobel Prize for Physiology or Medicine for 1956.

In 1945 Richards moved his lab to Bellevue Hospital, New York. In 1947 he was made the Lambert Professor of Medicine at Columbia University, where he had taught since 1925. During his career he also served as an advisor to Merck Sharp and Dohme Company, and edited the Merck Manual. Richards retired from his positions at Bellevue and Columbia in 1961.

Global policy

He was one of the signatories of the agreement to convene a convention for drafting a world constitution. As a result, for the first time in human history, a World Constituent Assembly convened to draft and adopt the Constitution for the Federation of Earth.

Honor

Richards received many other honors, including the John Phillips Memorial Award of the American College of Physicians in 1960, the Chevalier de la Legion d'Honneur in 1963, the Trudeau Medal in 1968, and the Kober Medal of the Association of American Physicians in 1970.

He died in Lakeville, Connecticut and his wife Constance in 1990.

Jai Ganesh · Dark Discussions at Cafe Infinity

Come Quotes - XV

1. Tell the truth, work hard, and come to dinner on time. - Gerald R. Ford

2. All the revision in the world will not save a bad first draft: for the architecture of the thing comes, or fails to come, in the first conception, and revision only affects the detail and ornament, alas! - T. E. Lawrence

3. 'Tis sweet to know there is an eye will mark our coming, and look brighter when we come. - Lord Byron

4. 'Obama and Biden want to raise taxes by a trillion dollars.' Guess what? Yes, we do in one regard: We want to let that trillion dollar tax cut expire so the middle class doesn't have to bear the burden of all that money going to the super-wealthy. That's not a tax raise. That's called fairness where I come from. - Joe Biden

5. And one who is just of his own free will shall not lack for happiness; and he will never come to utter ruin. - Aeschylus

6. Death means change our clothes. Clothes become old, then time to come change. So this body become old, and then time come, take young body. - Dalai Lama

7. Poetry is emotion put into measure. The emotion must come by nature, but the measure can be acquired by art. - Thomas Hardy

8. Basically it starts with four months of training, just basic stretching, kicking and punching. Then you come to the choreography and getting ready to put the dance together. - Keanu Reeves.

Jai Ganesh · Jokes

Q: What do you call a monkey that sells potato chips?
A: A chipmunk.
* * *
Q: What do you call a sleeping pizza?
A: A piZZZZZZa.
* * *
Q: Why did the boy put a candy bar under his pillow?
A: So he would have sweet dreams!
* * *
Q: If Jake has 30 chocolate bars, and eats 25, what does he have?
A: Diabetes..... Jake has diabetes...
* * *
Q: Why couldn't the teddy bear finish his dessert?
A: Because he was stuffed.
* * *

Jai Ganesh · This is Cool

Positron Emission Tomography

Gist

Positron emission tomography (PET) is a nuclear medicine imaging technique that uses radioactive tracers to visualize and measure metabolic activity and physiological functions in the body. By detecting gamma rays emitted from tracers (most commonly FDG), PET scans create 3D, high-resolution images to detect cancer, evaluate heart disease, and map brain disorders. (FDG: Fluorodeoxyglucose).

What is positron emission tomography used for?

Why is PET performed? In general, PET scans may be used to evaluate organs and/or tissues for the presence of disease or other conditions. PET may also be used to evaluate the function of organs, such as the heart or brain. The most common use of PET is in the detection of cancer and the evaluation of cancer treatment.

Summary

Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. In clinical practice it is used to diagnose and manage cancer treatment, in cardiology and cardiac surgery, and in neurology and psychiatry.

PET is a common imaging technique, a medical scintillography technique used in nuclear medicine. A radiopharmaceutical—a radioisotope attached to a drug—is injected into the body as a tracer. When the radiopharmaceutical undergoes beta plus decay, a positron is emitted, and when the positron interacts with an ordinary electron, the two particles annihilate and two gamma rays are emitted in opposite directions. These gamma rays are detected by two gamma cameras to form a three-dimensional image.

PET scanners can incorporate a computed tomography scanner (CT) and are known as PET–CT scanners. PET scan images can be reconstructed using a CT scan performed using one scanner during the same session.

One of the disadvantages of a PET scanner is its high initial cost and ongoing operating costs.

Details

Positron emission tomography (PET) is a type of nuclear medicine procedure that measures metabolic activity of the cells of body tissues. PET is actually a combination of nuclear medicine and biochemical analysis. Used mostly in patients with brain or heart conditions and cancer, PET helps to visualize the biochemical changes taking place in the body, such as the metabolism (the process by which cells change food into energy after food is digested and absorbed into the blood) of the heart muscle.

PET differs from other nuclear medicine examinations in that PET detects metabolism within body tissues, whereas other types of nuclear medicine examinations detect the amount of a radioactive substance collected in body tissue in a certain location to examine the tissue's function.

Since PET is a type of nuclear medicine procedure, this means that a tiny amount of a radioactive substance, called a radiopharmaceutical (radionuclide or radioactive tracer), is used during the procedure to assist in the examination of the tissue under study. Specifically, PET studies evaluate the metabolism of a particular organ or tissue, so that information about the physiology (functionality) and anatomy (structure) of the organ or tissue is evaluated, as well as its biochemical properties. Thus, PET may detect biochemical changes in an organ or tissue that can identify the onset of a disease process before anatomical changes related to the disease can be seen with other imaging processes such as computed tomography (CT) or magnetic resonance imaging (MRI).

PET is most often used by oncologists (doctors specializing in cancer treatment), neurologists and neurosurgeons (doctors specializing in treatment and surgery of the brain and nervous system), and cardiologists (doctors specializing in the treatment of the heart). However, as advances in PET technologies continue, this procedure is beginning to be used more widely in other areas.

PET may also be used in conjunction with other diagnostic tests, such as computed tomography (CT) or magnetic resonance imaging (MRI) to provide more definitive information about malignant (cancerous) tumors and other lesions. Newer technology combines PET and CT into one scanner, known as PET/CT. PET/CT shows particular promise in the diagnosis and treatment of lung cancer, evaluating epilepsy, Alzheimer's disease and coronary artery disease.

Originally, PET procedures were performed in dedicated PET centers, because the equipment to make the radiopharmaceuticals, including a cyclotron and a radiochemistry lab, had to be available, in addition to the PET scanner. Now, the radiopharmaceuticals are produced in many areas and are sent to PET centers, so that only the scanner is required to perform a PET scan.

Further increasing the availability of PET imaging is a technology called gamma camera systems (devices used to scan patients who have been injected with small amounts of radionuclides and currently in use with other nuclear medicine procedures). These systems have been adapted for use in PET scan procedures. The gamma camera system can complete a scan more quickly, and at less cost, than a traditional PET scan.

How does PET work?

PET works by using a scanning device (a machine with a large hole at its center) to detect photons (subatomic particles) emitted by a radionuclide in the organ or tissue being examined.

The radionuclides used in PET scans are made by attaching a radioactive atom to chemical substances that are used naturally by the particular organ or tissue during its metabolic process. For example, in PET scans of the brain, a radioactive atom is applied to glucose (blood sugar) to create a radionuclide called fluorodeoxyglucose (FDG), because the brain uses glucose for its metabolism. FDG is widely used in PET scanning.

Other substances may be used for PET scanning, depending on the purpose of the scan. If blood flow and perfusion of an organ or tissue is of interest, the radionuclide may be a type of radioactive oxygen, carbon, nitrogen, or gallium.

The radionuclide is administered into a vein through an intravenous (IV) line. Next, the PET scanner slowly moves over the part of the body being examined. Positrons are emitted by the breakdown of the radionuclide. Gamma rays called annihilation photons are created when positrons collide with electrons near the decay event. The scanner then detects the annihilation photons, which arrive at the detectors in coincidence at 180 degrees apart from one another. A computer analyzes those gamma rays and uses the information to create an image map of the organ or tissue being studied. The amount of the radionuclide collected in the tissue affects how brightly the tissue appears on the image, and indicates the level of organ or tissue function.

Why is PET performed?

In general, PET scans may be used to evaluate organs and/or tissues for the presence of disease or other conditions. PET may also be used to evaluate the function of organs, such as the heart or brain. The most common use of PET is in the detection of cancer and the evaluation of cancer treatment.

More specific reasons for PET scans include, but are not limited to, the following:

* To diagnose dementias (conditions that involve deterioration of mental function), such as Alzheimer's disease, as well as other neurological conditions such as:

** Parkinson's disease. A progressive disease of the nervous system in which a fine tremor, muscle weakness, and a peculiar type of gait are seen.
** Huntington's disease. A hereditary disease of the nervous system which causes increasing dementia, bizarre involuntary movements, and abnormal posture.
** Epilepsy. A brain disorder involving recurrent seizures.
** Cerebrovascular accident (stroke)

* To locate the specific surgical site prior to surgical procedures of the brain

* To evaluate the brain after trauma to detect hematoma (blood clot), bleeding, and/or perfusion (blood and oxygen flow) of the brain tissue

* To detect the spread of cancer to other parts of the body from the original cancer site

* To evaluate the effectiveness of cancer treatment

* To evaluate the perfusion (blood flow) to the myocardium (heart muscle) as an aid in determining the usefulness of a therapeutic procedure to improve blood flow to the myocardium

* To further identify lung lesions or masses detected on chest X-ray and/or chest CT

* To assist in the management and treatment of lung cancer by staging lesions and following the progress of lesions after treatment

* To detect recurrence of tumors earlier than with other diagnostic modalities

How is PET performed?

PET scans can be done on an outpatient basis. It is also possible that some hospital inpatients may undergo a PET examination for certain conditions.

Although each facility may have specific protocols in place, generally, a PET scan procedure follows this process:

1. The patient will be asked to remove any clothing, jewelry, or other objects that may interfere with the scan.

2. If asked to remove clothing, the patient will be given a gown to wear.

3. The patient will be asked to empty his or her bladder prior to the start of the procedure.

4. One or 2 IV lines will be started in the hand or arm for injection of the radionuclide.

5. Certain types of scans of the abdomen or pelvis may require that a urinary catheter be inserted into the bladder to drain urine during the procedure.

6. In some cases, an initial scan may be performed prior to the injection of the radionuclide, depending on the type of study being done. The patient will be positioned on a padded table inside the scanner.

7. The radionuclide will be injected into the IV. The radionuclide will be allowed to concentrate in the organ or tissue for about 30 to 60 minutes. The patient will remain in the facility during this time. The patient will not be hazardous to other people, as the radionuclide emits less radiation than a standard X-ray.

8. After the radionuclide has been absorbed for the appropriate length of time, the scan will begin. The scanner will move slowly over the body part being studied.

9. When the scan has been completed, the IV line will be removed. If a urinary catheter has been inserted, it will be removed.

Additional Information

Positron emission tomography, also called PET imaging or a PET scan, is a type of nuclear medicine imaging. A PET scan measures important body functions, such as blood flow, oxygen use, and sugar (glucose) metabolism, to help doctors evaluate how well organs and tissues are functioning.

PET is a powerful diagnostic test that is having a major impact on the diagnosis and treatment of disease. A PET scan (positron emission tomography scan) monitors the biochemical functioning of cells by detecting how they process certain compounds, such as glucose (sugar). PET can detect extremely small cancerous tumors, subtle changes of the brain and heart, and give doctors important early information about heart disease and many neurological disorders, like Alzheimer's.

Most common medical tests, like CT and MRI scans, only show details about the structure of your body. PET scans give doctors images of function throughout the entire body, uncovering abnormalities that might otherwise go undetected. This allows doctors to treat these diseases earlier and more accurately. A PET scan puts time on your side. The earlier the diagnosis, the better the chance for treatment.

For example, a PET scan is the most accurate, non-invasive way to tell whether or not a tumor is benign or malignant, sparing patients expensive, often painful diagnostic surgeries and suggesting treatment options earlier in the course of the disease. Although cancer spreads silently in the body, PET can inspect all organs of the body for cancer in a single examination.

Today, most PET scans are performed on instruments that are combined PET and CT scanners. The combined PET/CT scans provide images that pinpoint the location of abnormal metabolic activity within the body. The combined scans have been shown to provide more accurate diagnoses than the two scans performed separately.

About nuclear medicine

Nuclear medicine is a branch of medical imaging that uses small amounts of radioactive material to diagnose or treat a variety of diseases, including many types of cancers, heart disease, and certain other abnormalities within the body. Depending on the type of nuclear medicine exam you are undergoing, the radiotracer is either injected into a vein, swallowed or inhaled as a gas and eventually accumulates in the organ or area of your body being examined, where it gives off energy in the form of gamma rays. This energy is detected by a device called a gamma camera, a PET scanner and/or probe.

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Jai Ganesh · Science HQ

Latent Heat

Gist

Latent heat is the energy absorbed or released by a substance during a change in its physical state (solid, liquid, or gas) that occurs without changing its temperature. This "hidden" energy breaks or forms molecular bonds, with primary types being latent heat of fusion (melting/freezing) and vaporization (boiling/condensation).

Latent heat is the energy absorbed or released by a substance during a change of state (like melting, freezing, boiling, or condensing) without changing its temperature, acting as "hidden" energy to break or form molecular bonds. This energy is measured per unit mass (e.g., Joules/kg) and involves two main types: the latent heat of fusion (solid to liquid/liquid to solid) and the latent heat of vaporization (liquid to gas/gas to liquid).

Summary

Latent heat is energy absorbed or released by a substance during a change in its physical state (phase) that occurs without changing its temperature. The latent heat associated with melting a solid or freezing a liquid is called the heat of fusion; that associated with vaporizing a liquid or a solid or condensing a vapour is called the heat of vaporization. The latent heat is normally expressed as the amount of heat (in units of joules or calories) per mole or unit mass of the substance undergoing a change of state.

For example, when a pot of water is kept boiling, the temperature remains at 100 °C (212 °F) until the last drop evaporates, because all the heat being added to the liquid is absorbed as latent heat of vaporization and carried away by the escaping vapour molecules. Similarly, while ice melts, it remains at 0 °C (32 °F), and the liquid water that is formed with the latent heat of fusion is also at 0 °C. The heat of fusion for water at 0 °C is approximately 334 joules (79.7 calories) per gram, and the heat of vaporization at 100 °C is about 2,230 joules (533 calories) per gram. Because the heat of vaporization is so large, steam carries a great deal of thermal energy that is released when it condenses, making water an excellent working fluid for heat engines.

Latent heat arises from the work required to overcome the forces that hold together atoms or molecules in a material. The regular structure of a crystalline solid is maintained by forces of attraction among its individual atoms, which oscillate slightly about their average positions in the crystal lattice. As the temperature increases, these motions become increasingly violent until, at the melting point, the attractive forces are no longer sufficient to maintain the stability of the crystal lattice. However, additional heat (the latent heat of fusion) must be added (at constant temperature) in order to accomplish the transition to the even more-disordered liquid state, in which the individual particles are no longer held in fixed lattice positions but are free to move about through the liquid. A liquid differs from a gas in that the forces of attraction between the particles are still sufficient to maintain a long-range order that endows the liquid with a degree of cohesion. As the temperature further increases, a second transition point (the boiling point) is reached where the long-range order becomes unstable relative to the largely independent motions of the particles in the much larger volume occupied by a vapour or gas. Once again, additional heat (the latent heat of vaporization) must be added to break the long-range order of the liquid and accomplish the transition to the largely disordered gaseous state.

Latent heat is associated with processes other than changes among the solid, liquid, and vapour phases of a single substance. Many solids exist in different crystalline modifications, and the transitions between these generally involve absorption or evolution of latent heat. The process of dissolving one substance in another often involves heat; if the solution process is a strictly physical change, the heat is a latent heat. Sometimes, however, the process is accompanied by a chemical change, and part of the heat is that associated with the chemical reaction.

Details

Latent heat (also known as latent energy or heat of transformation) is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process—usually a first-order phase transition, like melting or condensation.

Latent heat can be understood as hidden energy which is supplied or extracted to change the state of a substance without changing its temperature or pressure. This includes the latent heat of fusion (solid to liquid), the latent heat of vaporization (liquid to gas) and the latent heat of sublimation (solid to gas).

The term was introduced around 1762 by Scottish chemist Joseph Black. Black used the term in the context of calorimetry where a heat transfer caused a volume change in a body while its temperature was constant.

In contrast to latent heat, sensible heat is energy transferred as heat, with a resultant temperature change in a body.

Usage

The terms sensible heat and latent heat refer to energy transferred between a body and its surroundings, defined by the occurrence or non-occurrence of temperature change; they depend on the properties of the body. Sensible heat is sensed or felt in a process as a change in the body's temperature. Latent heat is energy transferred in a process without change of the body's temperature, for example, in a phase change (solid/liquid/gas).

Both sensible and latent heats are observed in many processes of transfer of energy in nature. Latent heat is associated with the change of phase of atmospheric or ocean water, vaporization, condensation, freezing or melting, whereas sensible heat is energy transferred that is evident in change of the temperature of the atmosphere or ocean, or ice, without those phase changes, though it is associated with changes of pressure and volume.

The original usage of the term, as introduced by Black, was applied to systems that were intentionally held at constant temperature. Such usage referred to latent heat of expansion and several other related latent heats. These latent heats are defined independently of the conceptual framework of thermodynamics.

When a body is heated at constant temperature by thermal radiation in a microwave field for example, it may expand by an amount described by its latent heat with respect to volume or latent heat of expansion, or increase its pressure by an amount described by its latent heat with respect to pressure.

Latent heat is energy released or absorbed by a body or a thermodynamic system during a constant-temperature process. Two common forms of latent heat are latent heat of fusion (melting) and latent heat of vaporization (boiling). These names describe the direction of energy flow when changing from one phase to the next: from solid to liquid, and liquid to gas.

In both cases the change is endothermic, meaning that the system absorbs energy. For example, when water evaporates, an input of energy is required for the water molecules to overcome the forces of attraction between them and make the transition from water to vapor.

If the vapor then condenses to a liquid on a surface, then the vapor's latent energy absorbed during evaporation is released as the liquid's sensible heat onto the surface.

The large value of the enthalpy of condensation of water vapor is the reason that steam is a far more effective heating medium than boiling water, and is more hazardous.

Meteorology

In meteorology, latent heat flux is the flux of energy from the Earth's surface to the atmosphere that is associated with evaporation or transpiration of water at the surface and subsequent condensation of water vapor in the troposphere. It is an important component of Earth's surface energy budget. Latent heat flux has been commonly measured with the Bowen ratio technique, or more recently since the mid-1900s by the eddy covariance method.

Additional Information

Latent heat is defined as the heat or energy that is absorbed or released during a phase change of a substance. It could either be from a gas to a liquid or liquid to a solid and vice versa. Latent heat is related to a heat property called enthalpy.

However, an important point that we should consider regarding latent heat is that the temperature of the substance remains constant. As far as the mechanism is concerned, latent heat is the work that is needed to overcome the attractive forces that hold molecules and atoms together in a substance.

Let’s take an example. Suppose a solid substance is changing to a liquid; it needs to absorb energy to push the molecules into a wider, more fluid volume. Similarly, when a substance changes from a gas phase to a liquid, its density levels also need to go from a lower to a higher level, wherein the substance then needs to release or lose energy so that the molecules come closer together. In essence, this energy that is required by a substance to either freeze, melt or boil is said to be latent heat.

Early Developments of the Concept

The Scottish scientific expert, Joseph Black, presented the idea of latent heat somewhere close to the period 1750 and 1762. Scotch bourbon producers had employed Black to decide the best blend of fuel and water for refining and to examine changes in volume and weight at a steady temperature. Dark applied calorimetry for his investigation and recorded latent heat esteems.

British physicist James Prescott Joule portrayed latent heat as a type of potential vitality. Joule accepted that vitality relied upon the specific design of particles in a substance. Actually, it is the direction of particles inside an atom, their substance holding, and their extremity that influence latent heat.

Types of Latent Heat Transfer

Lets us discuss some of the different types of latent heat that can occur.

Latent Heat of Fusion

The latent heat of fusion is the heat consumed or discharged when matter melts, changing state from solid to fluid structure at a consistent temperature.

The ‘enthalpy’ of fusion is a latent heat, in light of the fact that during softening, the heat energy expected to change the substance from solid to fluid at air pressure is the latent heat of fusion, as the temperature stays steady during the procedure. The latent heat of fusion is the enthalpy change of any measure of substance when it dissolves.

At the point when the heat of fusion is referenced to a unit of mass, it is typically called the specific heat of fusion, while the molar heat of fusion alludes to the enthalpy change per measure of substance in moles.

The fluid state has higher inward energy than the solid state. This implies that energy must be provided to the solid so as to dissolve it, and energy is discharged from a fluid when it solidifies on the grounds that the particles in the fluid experience more fragile intermolecular force, and thus have higher potential energy (a sort of bond-separation energy for intermolecular powers).

At the point when fluid water is cooled, its temperature falls relentlessly until it drops just underneath the line of the point of solidification at 0 °C. The temperature at that point stays consistent at the point of solidification while the water takes shape. When the water is totally solidified, its temperature keeps on falling.

The enthalpy of fusion is quite often a positive amount; helium is the main known exception. Helium-3 has a negative enthalpy of fusion at temperatures beneath 0.3 K. Helium-4 additionally has a marginally negative enthalpy of fusion underneath 0.77 K (−272.380 °C). This implies that at suitable steady weights, these substances solidify with the expansion of heat. For the situation of 4He, this weight territory is somewhere in the range of 24.992 and 25.00 atm (2,533 kPa).

Latent Heat of Vaporization

Latent heat of vaporization is the heat consumed or discharged when matter disintegrates, changing state from fluid to gas state at a consistent temperature.

The heat of vaporization of water is the highest known. The heat of vaporization is characterised as the measure of heat expected to transform 1 g of a fluid into a fume without a change in the temperature of the fluid. This term isn’t in the rundown of definitions given by Weast (1964), so the definition originates from Webster’s New World Dictionary of the American Language (1959). The units are cal/gram. The heat of vaporization is latent heat. The word latent originates from the Latin word latere, which intends to lie covered up or hidden. Latent heat is the extra heat required to change the condition of a substance from solid to fluid at its softening point, or from fluid to gas at its breaking point after the temperature of the substance has come to both of these focuses.

Note that latent heat is related to no adjustment in temperature, yet a difference in the state. As a result of the high heat of vaporization, the vanishing of water has an articulated cooling impact, and buildup has a warming impact.

Similar to the case for ‘Heat of Fusion/Melting,’ the heat of vaporization/buildup additionally speaks to the measure of heat traded during a stage move. For vaporization, it is the amount of heat (540 cal g^{-1}) expected to change over 1 g of water to 1 g of water fume. A similar measure of heat is traded or discharged in the stage move during the buildup of 1 g water fume to 1 g of water.

Amphibian researchers might be normally intrigued with the enormous measure of heat traded (80 cal g−1) in the stage move from water to ice or from ice to water, yet the measure of heat traded (540 cal g^{-1}) in the stage move from water to water fume, or water fume to water is 6.75 times bigger (540/80 = 6.75). Despite the fact that the significance of this enormous measure of heat trade through vaporization or buildup might be undervalued by people, it is immense. On a little yet basic scale forever, water dissipating off sweating warm-blooded creatures, including people, keeps up internal heat levels inside thin survivable points of confinement. On a worldwide scale, the apparently perpetual stage moves between fluid water and water fume in the climate are the key determinants in the redistribution of water and heat inside the hydrological cycle far and wide.

The enthalpy of vaporization, ΔHv, is additionally named the “latent heat of vaporization.” And ΔHv is the distinction between the enthalpy of the soaked fume and that of the immersed fluid at a similar temperature. The enthalpy of vaporization information is utilised in process estimations, for example, the plan of alleviation frameworks, including unpredictable mixes. In refining, the heat of vaporization esteems are expected to discover the heat loads for the reboiler and condenser, and information on the enthalpy of vaporization is required in the structure of heat exchangers for disintegrating fluids.

Reasonable Heat

Although reasonable heat is frequently called latent heat, it is anything but a steady temperature circumstance or is a stage change included. Reasonable heat reflects heat move among an item and its environment. The heat can be “detected” as an adjustment in an item’s temperature.

Reasonable Heat and Meteorology

While latent heat of combination and vaporization are utilised in material science and science, meteorologists also consider reasonable heat. At the point when latent heat is ingested or discharged, it produces insecurity in the climate, conceivably delivering an extreme climate. The change in latent heat adjusts the temperature into contact with hotter or cooler air. Both latent and reasonable heat cause air to move, creating wind and vertical movement of air masses.

Instances of Latent and Sensible Heat

Everyday life is loaded up with instances of latent and reasonable heat:

Bubbling water on a stove happens when warm vitality from the heating component is moved to the pot, and thus to the water. At the point when enough vitality is provided, fluid water grows from the water fume and the water bubbles. A gigantic measure of vitality is discharged when water bubbles are formed. Since water has such a high heat of vaporization, it’s anything but difficult to get scorched by steam.

Correspondingly, significant energy must be assimilated to change over fluid water to ice in a cooler. The cooler expels heat energy to permit the stage progress to happen. Water has a high latent heat of combination, so transforming water into ice requires the expulsion of more energy than solidifying fluid oxygen into solid oxygen per unit gram.

Specific Latent Heat

Specific latent heat is characterised as the measure of heat energy (heat, Q) that is consumed or discharged when a body experiences a steady temperature process.

The formula for specific latent heat is:

L = Q/m

Where:

L is the specific latent heat

Q is the heat retained or discharged

m is the mass of a substance.

The most widely recognised kinds of consistent temperature forms are stage changes, for example, liquefying, solidifying, vaporization, or buildup. The energy is viewed as “latent” on the grounds that it is basically covered up inside the atoms until the stage change happens. The most well-known units of specific latent heat are joules per gram (J/g) and kilojoules per kilogram (kJ/kg).

Specific latent heat is an escalated property of the issue.

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Jai Ganesh · This is Cool

2505) Atrophy

Gist

Atrophy is the wasting away, thinning, or decrease in size of cells, tissues, or organs, resulting in reduced function. It is caused by factors like disuse, poor circulation, nerve damage, malnutrition, or hormonal changes. Common forms include muscle, brain, or vaginal atrophy, often characterized by weakness and reduced size of the affected area.

Brain atrophy means the progressive loss of brain cells (neurons) and their connections, causing the brain to shrink in overall size or in specific regions, leading to impaired cognitive, motor, or functional abilities, and can be a normal part of aging or a symptom of diseases like Alzheimer's or MS (Multiple Sclerosis). It's diagnosed via brain scans like MRIs and CTs, which reveal the tissue loss, and treatment focuses on managing the underlying cause.

Summary

Muscle atrophy is the wasting or thinning of muscle mass. It can be caused by disuse of your muscles or neurogenic conditions. Symptoms include a decrease in muscle mass, one limb being smaller than the other, and numbness, weakness and tingling in your limbs. Disuse atrophy can be reversed with exercise and a healthy diet.

Muscle atrophy is the loss or thinning of your muscle tissue. If you have atrophied muscles, you’ll see a decrease in your muscle mass and strength. With muscle atrophy, your muscles look smaller than normal. Muscle atrophy can occur due to malnutrition, age, genetics, a lack of physical activity or certain medical conditions. Disuse (physiologic) atrophy occurs when you don’t use your muscles enough. Neurogenic atrophy occurs due to nerve problems or diseases.

What are the symptoms of muscle atrophy?

The symptoms of muscle atrophy differ depending on the cause of your condition. The most obvious sign of muscle atrophy is reduced muscle mass. Other signs of muscle atrophy may include:

* One arm or one leg is smaller than the other.
* Weakness in one arm and or one leg.
* Numbness or tingling in your arms and legs.
* Trouble walking or balancing.
* Difficulty swallowing or speaking.
* Facial weakness.
* Gradual memory loss.

Details

Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply to the target organ, excessive amount of apoptosis of cells, and disuse or lack of exercise or disease intrinsic to the tissue itself. In medical practice, hormonal and nerve inputs that maintain an organ or body part are said to have trophic effects. A diminished muscular trophic condition is designated as atrophy. Atrophy is reduction in size of cell, organ or tissue, after attaining its normal mature growth. In contrast, hypoplasia is the reduction in the cellular numbers of an organ, or tissue that has not attained normal maturity.

Atrophy is the general physiological process of reabsorption and breakdown of tissues, involving apoptosis. When it occurs as a result of disease or loss of trophic support because of other diseases, it is termed pathological atrophy, although it can be a part of normal body development and homeostasis as well.

Examples of atrophy as part of normal development include shrinking and the involution of the thymus in early childhood, and the tonsils in adolescence. In old age, effects include, but are not limited to, loss of teeth, hair, thinning of skin that creates wrinkles, weakening of muscles, loss of weight in organs and sluggish mental activity.

Muscle atrophies

Disuse atrophy of muscles and bones, with loss of mass and strength, can occur after prolonged immobility, such as extended bedrest, or having a body part in a cast (living in darkness for the eye, bedridden for the legs etc.). This type of atrophy can usually be reversed with exercise unless severe.

There are many diseases and conditions which cause atrophy of muscle mass. For example, diseases such as cancer and AIDS induce a body wasting syndrome called cachexia, which is notable for the severe muscle atrophy seen. Other syndromes or conditions which can induce skeletal muscle atrophy are congestive heart failure and liver disease.

During aging, there is a gradual decrease in the ability to maintain skeletal muscle function and mass. This condition is called sarcopenia, and may be distinct from atrophy in its pathophysiology. While the exact cause of sarcopenia is unknown, it may be induced by a combination of a gradual failure in the satellite cells which help to regenerate skeletal muscle fibers, and a decrease in sensitivity to or the availability of critical secreted growth factors which are necessary to maintain muscle mass and satellite cell survival.

Dystrophies, myositis, and motor neuron conditions

Pathologic atrophy of muscles can occur with diseases of the motor nerves or diseases of the muscle tissue itself. Examples of atrophying nerve diseases include Charcot-Marie-Tooth disease, poliomyelitis, amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease), and Guillain–Barré syndrome. Examples of atrophying muscle diseases include muscular dystrophy, myotonia congenita, and myotonic dystrophy.

Changes in Na+ channel isoform expression and spontaneous activity in muscle called fibrillation can also result in muscle atrophy.

A flail limb is a medical term which refers to an extremity in which the primary nerve has been severed, resulting in complete lack of mobility and sensation. The muscles soon wither away from atrophy.

Gland atrophy

The adrenal glands atrophy during prolonged use of exogenous glucocorticoids like prednisone. Atrophy of the breasts can occur with prolonged estrogen reduction, as with anorexia nervosa or menopause. Testicular atrophy can occur with prolonged use of enough exogenous sex steroids (either androgen or estrogen) to reduce gonadotropin secretion.

Vaginal atrophy

In post-menopausal women, the walls of the math become thinner (atrophic vaginitis). The mechanism for the age-related condition is not yet clear, though there are theories that the effect is caused by decreases in estrogen levels. This atrophy, occurring concurrently with breast atrophy, is consistent with the homeostatic (normal development) role of atrophy in general, as after menopause the body has no further functional biological need to maintain the reproductive system which it has permanently shut down.

Research

One drug in test seemed to prevent the type of muscle loss that occurs in immobile, bedridden patients. Testing on mice showed that it blocked the activity of a protein present in the muscle that is involved in muscle atrophy. However, the drug's long-term effect on the heart precludes its routine use in humans, and other drugs are being sought.

Additional Information

Atrophy is a decrease in size of a body part, cell, organ, or other tissue. The term implies that the atrophied part was of a size normal for the individual, considering age and circumstance, prior to the diminution. In atrophy of an organ or body part, there may be a reduction in the number or in the size of the component cells, or in both.

Certain cells and organs normally undergo atrophy at certain ages or under certain physiologic circumstances. In the human embryo, for example, a number of structures are transient and at birth have already undergone atrophy. The adrenal glands become smaller shortly after birth because an inner layer of the cortex has shrunk. The thymus and other lymphoid tissues atrophy at adolescence. The pineal gland tends to atrophy about the time of puberty; usually calcium deposits, or concretions, form in the atrophic tissue. The widespread atrophy of many tissues that accompanies advanced age, although universal, is influenced by changes of nutrition and blood supply that occur during active mature life.

The normal cyclic changes of female reproductive organs are accompanied by physiologic atrophy of portions of these organs. During the menstrual cycle, the corpus luteum of the ovary atrophies if pregnancy has not occurred. The muscles of the uterus, which enlarge during pregnancy, rapidly atrophy after the delivery of the child, and after completion of lactation the milk-producing acinar structures of the breast diminish in size. After menopause the ovaries, uterus, and breasts normally undergo a degree of atrophic change.

Whole body atrophy

Atrophy in general is related to changes in nutrition and metabolic activity of cells and tissues. A widespread or generalized atrophy of body tissues occurs under conditions of starvation, whether because food is unavailable or because it cannot be taken and absorbed because of the presence of disease. The unavailability of certain essential protein components and vitamins disturbs the metabolic processes and leads to atrophy of cells and tissues. Under conditions of protein starvation, the body protein is broken down into constituent amino acids, which serve to provide energy and help maintain the structure and cells of the most essential organs. The brain, heart, adrenal glands, thyroid gland, pituitary gland, gonads, and kidneys show less atrophy, relatively, than the body as a whole, whereas the fatty stores of the body, liver, spleen, and lymphoid tissues diminish relatively more than the body as a whole. The brain, heart, and kidneys, organs with abundant blood supply, appear to be the least subject to the wasting effects of starvation.

Associated with the widespread atrophy due to lack of protein is the atrophy of certain tissues that is caused by deficiencies of specific vitamins. Atrophic changes of the skin increase because of the lack of vitamin A, and atrophy of muscle increases because of the unavailability of vitamin E.

After a growth period of human metabolism, there sets in a gradual decline: slow structural changes other than those due to preventable diseases or accidents occur. Aging eventually is characterized by marked atrophy of many tissues and organs, with both a decline in the number of cells and an alteration in their constitution. This is reflected eventually in the changed, diminished, or lost function characteristic of old age and eventuates in death. The changes in senescence are affected by both inherited constitution and environmental influences, including disease and accident.

Atrophic changes of aging affect almost all tissues and organs, but some changes are more obvious and important. Arteriosclerosis—the thickening and hardening of arterial walls—decreases the vascular supply and usually accentuates aging processes.

Atrophy in old age is especially noticeable in the skin, characteristically flat, glossy or satiny, and wrinkled. The atrophy is caused by aging changes in the fibres of the true skin, or dermis, and in the cells and sweat glands of the outer skin. Wasting of muscle accompanied by some loss of muscular strength and agility is common in the aged. In a somewhat irregular pattern, there is shrinkage of many individual muscle fibres as well as a decrease in their number. Other changes have been observed within the muscle cells.

Increase of the pigment lipofuscin is also characteristic in the muscle fibres of the heart in the aged in a condition known as brown atrophy of the heart. Wasting of the heart muscle in old age may be accompanied by increase of fibrous and fatty tissue in the walls of the right side of the heart and by increased replacement of elastic tissue with fibrous tissue in the lining and walls of coronary arteries within the heart muscle. Abnormal deposits of the protein substance amyloid also occur with greater frequency in the atrophic heart muscle in old age.

Atrophy of the liver in the aged is also accompanied by increased lipochrome pigment in the atrophied cells.

The bones become progressively lighter and more porous with aging, a process known as osteoporosis. The reduction of bone tissue is most marked in cancellous bone—the open-textured tissue in the ends of the long bones—and in the inner parts of the cortex of these bones. In addition to changes in and loss of osteocytes, or bone cells, there is decreasing mineralization, or calcium deposit, with enhanced fragility of the bones.

Atrophy of the brain in old age is shown by narrowing of the ridges, or gyri, on the surface of the brain and by increased fluid in the space beneath the arachnoid membrane, the middle layer of the brain covering. There is shrinkage of individual neurons, with an increase in their lipochrome pigment content, as well as a decrease in their number. Sometimes the nerve fibrils have degenerated, and deposits called senile plaques may be found between the neurons, particularly in the frontal cortex and hippocampus (a ridge in the wall of an extension, or horn, of the lateral ventricle, or cavity, of the brain). Similar atrophic changes are seen in the brain in Alzheimer disease, a condition of unknown cause most likely to occur in older patients. The mental deterioration (senile dementia) of the aged is the clinical manifestation of these changes. Senile atrophy may be increased and complicated by the presence of arteriosclerosis.

Simmonds disease is a chronic deficiency of function of the pituitary gland, a form of hypopituitarism, that leads to atrophy of many of the viscera, including the heart, liver, spleen, kidneys, thyroid, adrenals, and gonads. The disease results in emaciation and death if left untreated.

A destructive or atrophic lesion affecting the pituitary gland with loss of hormones leads to atrophy of the thyroid gland, adrenal glands, and gonads and in turn brings atrophic changes to their target organs and the viscera. The decrease in size of the endocrine glands may be extreme.

Atrophy of muscle or of muscle and bone

Local atrophy of muscle, bone, or other tissues results from disuse or diminished activity or function. Although the exact mechanisms are not completely understood, decreased blood supply and diminished nutrition occur in inactive tissues. Disuse of muscle resulting from loss of motor nerve supply to the muscle (e.g., as a result of polio) leads to extreme inactivity and corresponding atrophy. Muscles become limp and paralyzed if there is destruction of the nerve cells in the spinal cord that normally activate them. The shrinkage of the paralyzed muscle fibres becomes evident within a few weeks. After some months, fragmentation and disappearance of the muscle fibres occurs with some replacement by fat cells and a loose network of connective tissue. Some contracture may result.

The skeletal muscles forced to inactivity by paralysis (e.g., of a limb as a result of polio) also undergo disuse atrophy. If there is a tendency for bone to become lighter and more porous in some particular area, a condition known as local osteoporosis, this can be recognized by X-rays within a few weeks. The cortex of the long bones becomes considerably thinned or atrophic, with decreased mineral content. Disuse as a result of painfully diseased joints, as in rheumatoid arthritis, results in a similar but lesser degree of atrophy of muscles concerned with movement of the involved joint, and local atrophy may also occur in the bone in the neighbourhood of the joint. A local osteoporosis of bone known as Sudeck atrophy sometimes develops rapidly in the area of an injury to bone.

Severe or prolonged deficits of blood sugar deprive the nervous system of needed sources of energy and as a rare event result in degeneration of cells of the brain and peripheral nerves. The disuse atrophy of muscle or bone that may result is fundamentally similar to the other disuse atrophies of these tissues.

Persistent pressure will cause atrophy of a compressed cell, organ, or tissue, presumably because of interference with the nutrition and metabolic activity of the affected part. Cells in a local area (e.g., in the liver) atrophy from the pressure of materials such as amyloid deposited around them. The pressure of an expanding benign tumour causes atrophy of adjacent normal structures. The pressure of a localized dilatation of an artery (aneurysm) will cause atrophy of tissues, even bone, on which it impinges.

Bulging of an intervertebral disk or growth of a tumour sometimes brings pressure on nerves near their point of exit from the spinal cord; if the pressure is prolonged, the muscles normally controlled by these nerves may atrophy. Most often the calf muscles are affected. Pressure as a result of involvement of the vertebrae at the level of the neck, or from compression of the network of nerves called the brachial plexus by the scalenus anticus muscle, produces similar effects in the upper chest and arms.

Simple disuse of muscle or bone, as, for example, from the immobilization produced when a limb is put in a cast or sling, results in atrophy of these tissues. In the case of muscle, the degree of atrophy is generally less severe than that caused by injury to a nerve, although the nature of the change is similar.

Localized atrophies of leg and arm muscles may result from hereditary or familial diseases in which the nerves of the spinal cord that supply them are inactivated or destroyed. In Charcot-Marie-Tooth disease, the atrophy involves mainly the peroneal muscles, at the outer side of the lower legs, and sometimes the muscles of the hand as well. It commonly begins in childhood or adolescence. Peroneal muscle atrophy is also seen in the hereditary spinal cord degenerative disease known as Friedreich ataxia.

Atrophy of nerve tissue

Atrophy of brain or spinal cord tissue may be brought about by injuries that directly affect a localized area or that interfere with the blood supply to an area. When peripheral nerves are severed, degenerative and eventually atrophic changes ensue in the part beyond the injury. This type of atrophy is known as Wallerian degeneration. If conditions do not allow regeneration of nerve fibres from the proximal fragment of the cut nerve, atrophy is the eventual fate of the nerve tissue distal to the injury. Retrograde atrophy also occurs from disuse and affects the ganglion cells of the injured nerve.

Prolonged pressure brings about atrophy in the central nervous system as elsewhere. The pressure of an expanding tumour of the membranes covering the brain results in localized atrophy of the adjacent brain substance on which it impinges. In hydrocephalus more widespread atrophy of brain tissue results from the abnormal amounts of fluid confined within the rigid bony compartment of the skull. Increased pressure within the skull may force a portion of the brain through the foramen magnum, the bony opening at the base of the skull, and, if prolonged, results in a localized atrophy of cerebellar tissue pressed against the bony wall.

The late stages of chronic infections may be characterized by atrophy of the brain. A striking example of this is the variety of syphilitic infection of the nervous system known as general paresis in which the brain is shrunk and reduced in weight, the atrophy affecting mainly the cortex of the brain, particularly or most markedly in the frontal area. Occasionally the atrophy is local or affects only one side of the brain. The shrinkage of the brain tissue is mainly due to loss of many nerve cells of the cortex.

Atrophy of fatty tissue

Atrophy of adipose tissue of the body occurs as a part of the generalized atrophy of prolonged undernutrition. Localized atrophy of adipose tissue—lipodystrophy—may be the result of injury to the local area; e.g., repeated insulin injections cause atrophy of fatty tissue at the site of the injections. Progressive lipodystrophy is a disease of unknown cause in which the fatty tissue atrophies only in certain regions of the body. It occurs mainly in women and often begins in childhood. The progressive wasting of adipose tissue affects mainly the face, arms, and trunk. In the affected areas, the specialized fat-holding cells of adipose tissue disappear.

Atrophy of skin

A widespread atrophic change in the skin has been noted as a prominent part of the aging process. Similar atrophic changes in the skin appear to be brought about or enhanced by excessive exposure to sunlight. While a number of abnormal conditions of the skin may include localized atrophic changes in the epidermis or dermis as a part of their lesions, certain generalized diseases of the skin are particularly characterized by such changes. The hardening of the skin known as scleroderma may occur in a localized, or circumscribed, form called morphea or as a more diffuse and severe disease. Advanced stages of scleroderma are characterized by marked atrophy of the tissue and appendages of the true skin. Atrophic thinning of the overlying epidermis also may occur, and the underlying fatty tissue and muscle may atrophy as well. The chronic form of the disease discoid lupus erythematosus also is characterized by atrophy. In advanced stages atrophy occurs particularly in the epidermis in focal areas. The thinned layer of epidermis may be a prominent feature of the microscopic appearance of the skin.

Atrophy of glands

Endocrine glandular tissues may undergo atrophy when an excess of their hormonal product is present as a result of disease. An example is seen in connection with a hormone-producing tumour of the cortical tissue of one adrenal gland, which may be accompanied by marked atrophy of the cortical tissue of the opposite adrenal gland. This probably results from disturbance of the delicate mechanism of hormonal stimulation via the pituitary gland.

Various endocrine organs (thyroid gland, adrenal glands, gonads) depend for their activity on endocrine stimulation by hormones of the pituitary gland. A severe general failure of production of the pituitary hormones results in the widespread endocrine atrophy of Simmonds disease, as has been noted. Lesser degrees of pituitary functional disturbance may disturb a delicate balance, involving mainly one type of stimulating hormone of the pituitary, and may result in selective atrophy of the adrenal cortical tissue or of the gonads.

Glands that release their secretions through a duct (e.g., salivary glands, pancreas) may become atrophic as a result of obstruction of the duct. In the pancreas, a complete obstruction of its duct results in atrophy of the glandular tissue, except for the insulin-producing islets of Langerhans, the secretion of which is absorbed into the bloodstream. Factors of both disuse and increased pressure may be present in the atrophy resulting from obstruction of the outlet channel. Similarly, rapid and complete obstruction of a ureter is followed by atrophy of the corresponding kidney.

Chemical-induced atrophy

Cases of atrophy resulting from chemical injury are not common. In chronic math poisoning, however, degenerative changes occur in peripheral nerves, resulting in weakness and atrophy in the tissues (usually legs or arms) to which the nerves are distributed. Similar results may follow the peripheral neuropathy of chronic lead poisoning.

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