Posts by Jai Ganesh

Jai Ganesh · This is Cool

Glacier

Gist

A glacier is a large, persistent body of dense ice that forms on land over centuries as snow accumulates, compresses, and recrystallizes, moving slowly downhill under its own weight. Covering about 10% of Earth's land, these "rivers of ice" store ~69% of the world's freshwater and are critical indicators of climate change.

A glacier is a large, persistent body of dense ice that forms on land from compacted snow and moves slowly downhill under its own weight and gravity, essentially acting as a "river of ice" that carves landscapes as it flows. They form in areas where snow accumulation exceeds melting over many years, compressing into solid glacial ice, and are crucial indicators of climate change, holding vast amounts of freshwater.

Summary

A glacier is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as crevasses and seracs, as it slowly flows and deforms under stresses induced by its weight. As it moves, it abrades rock and debris from its substrate to create landforms such as cirques, moraines, or fjords. Although a glacier may flow into a body of water, it forms only on land and is distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.

On Earth, 99% of glacial ice is contained within vast ice sheets (also known as "continental glaciers") in the polar regions, but glaciers may be found in mountain ranges on every continent other than the Australian mainland, including Oceania's high-latitude oceanic island countries such as New Zealand. Between latitudes 35°N and 35°S, glaciers occur only in the Himalayas, Andes, and a few high mountains in East Africa, Mexico, New Guinea and on Zard-Kuh in Iran. With more than 7,000 known glaciers, Pakistan has more glacial ice than any other country outside the polar regions. Glaciers cover about 10% of Earth's land surface. Continental glaciers cover nearly 13 million {km}^{2} (5 million sq mi) or about 98% of Antarctica's 13.2 million sq km (5.1 million sq mi), with an average thickness of ice 2,100 m (7,000 ft). Greenland and Patagonia also have huge expanses of continental glaciers. The volume of glaciers, not including the ice sheets of Antarctica and Greenland, has been estimated at 170,000 {km}^{3}.

Glacial ice is the largest reservoir of fresh water on Earth, holding with ice sheets about 69% of the world's freshwater. Many glaciers from temperate, alpine and seasonal polar climates store water as ice during the colder seasons and release it later in the form of meltwater as warmer summer temperatures cause the glacier to melt, creating a water source that is especially important for plants, animals and human uses when other sources may be scant. However, within high-altitude and Antarctic environments, the seasonal temperature difference is often not sufficient to release meltwater.

Since glacial mass is affected by long-term climatic changes, e.g., precipitation, mean temperature, and cloud cover, glacial mass changes are considered among the most sensitive indicators of climate change and are a major source of variations in sea level.

A large piece of compressed ice, or a glacier, appears blue, as large quantities of water appear blue, because water molecules absorb other colors more efficiently than blue. The other reason for the blue color of glaciers is the lack of air bubbles. Air bubbles, which give a white color to ice, are squeezed out by pressure increasing the created ice's density.

Details

A glacier is any large mass of perennial ice that originates on land by the recrystallization of snow or other forms of solid precipitation and that shows evidence of past or present flow.

Exact limits for the terms large, perennial, and flow cannot be set. Except in size, a small snow patch that persists for more than one season is hydrologically indistinguishable from a true glacier. One international group has recommended that all persisting snow and ice masses larger than 0.1 square kilometre (about 0.04 square mile) be counted as glaciers.

General observations:

Main types of glaciers

Glaciers are classifiable in three main groups: (1) glaciers that extend in continuous sheets, moving outward in all directions, are called ice sheets if they are the size of Antarctica or Greenland and ice caps if they are smaller; (2) glaciers confined within a path that directs the ice movement are called mountain glaciers; and (3) glaciers that spread out on level ground or on the ocean at the foot of glaciated regions are called piedmont glaciers or ice shelves, respectively. Glaciers in the third group are not independent and are treated here in terms of their sources: ice shelves with ice sheets, piedmont glaciers with mountain glaciers. A complex of mountain glaciers burying much of a mountain range is called an ice field.

Distribution of glaciers

A most interesting aspect of recent geological time (some 30 million years ago to the present) has been the recurrent expansion and contraction of the world’s ice cover. These glacial fluctuations influenced geological, climatological, and biological environments and affected the evolution and development of early humans. Almost all of Canada, the northern third of the United States, much of Europe, all of Scandinavia, and large parts of northern Siberia were engulfed by ice during the major glacial stages. At times during the Pleistocene Epoch (from 2.6 million to 11,700 years ago), glacial ice covered 30 percent of the world’s land area; at other times the ice cover may have shrunk to less than its present extent. It may not be improper, then, to state that the world is still in an ice age. Because the term glacial generally implies ice-age events or Pleistocene time, in this discussion “glacier” is used as an adjective whenever reference is to ice of the present day.

Glacier ice today stores about three-fourths of all the fresh water in the world. Glacier ice covers about 11 percent of the world’s land area and would cause a world sea-level rise of about 90 metres (300 feet) if all existing ice melted. Glaciers occur in all parts of the world and at almost all latitudes. In Ecuador, Kenya, Uganda, and Irian Jaya (New Guinea), glaciers even occur at or near the Equator, albeit at high altitudes.

Glaciers and climate

The cause of the fluctuation of the world’s glacier cover is still not completely understood. Periodic changes in the heat received from the Sun, caused by fluctuations in the Earth’s orbit, are known to correlate with major fluctuations of ice sheet advance and retreat on long time scales. Large ice sheets themselves, however, contain several “instability mechanisms” that may have contributed to the larger changes in world climate. One of these mechanisms is due to the very high albedo, or reflectivity of dry snow to solar radiation. No other material of widespread distribution on the Earth even approaches the albedo of snow. Thus, as an ice sheet expands it causes an ever larger share of the Sun’s radiation to be reflected back into space, less is absorbed on the Earth, and the world’s climate becomes cooler. Another instability mechanism is implied by the fact that the thicker and more extensive an ice sheet is, the more snowfall it will receive in the form of orographic precipitation (precipitation resulting from the higher altitude of its surface and attendant lower temperature). A third instability mechanism has been suggested by studies of the West Antarctic Ice Sheet. Portions of an ice sheet called ice streams may periodically move rapidly outward, perhaps because of the buildup of a thick layer of wet, deformable material under the ice. Although the ultimate causes of ice ages are not known with certainty, scientists agree that the world’s ice cover and climate are in a state of delicate balance.

Only the largest ice masses directly influence global climate, but all ice sheets and glaciers respond to changes in local climate—particularly changes in air temperature or precipitation. The fluctuations of these glaciers in the past can be inferred by features they have left on the landscape. By studying these features, researchers can infer earlier climatic fluctuations.

Additional Information

Glaciers are large, thick masses of ice that form on land when fallen snow gets compressed into ice over many centuries.

Glaciers are massive bodies of slowly moving ice. Glaciers form on land, and they are made up of fallen snow that gets compressed into ice over many centuries. They move slowly downward from the pull of gravity.

Most of the world’s glaciers exist in the polar regions, in areas like Greenland, the Canadian Arctic, and Antarctica. Glaciers also can be found closer to the Equator in some mountain regions. The Andes Mountain range in South America contains some of the world’s largest tropical glaciers. About 2 percent of all the water on Earth is frozen in glaciers.

Glaciers can range in age from a couple hundred to thousands of years old. Most glaciers today are remnants of the massive ice sheets that covered Earth during the Ice Age. The Ice Age ended more than 10,000 years ago. During Earth’s history, there have been colder periods—when glaciers formed—and warmer periods—when glaciers melted.

Scientists who study glaciers are called glaciologists. Glaciologists began studying glaciers during the 19th century in order to look for clues about past ice ages. Today, glaciologists study glaciers for clues about global warming. Old photographs and paintings show that glaciers have melted away from mountain regions over time. Indeed, glaciers worldwide have been shrinking—and even disappearing—at an accelerated rate for the past several decades.

Among the scientists studying the changes in glaciers is Erin Christine Pettit, a glaciologist at the University of Alaska Fairbanks. Pettit observes and measures the flow, fracture, and retreat of glaciers. She uses this information to study how much water enters the oceans from melting glaciers. Melting glaciers are one factor contributing to the global sea-level rise.

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Jai Ganesh · Dark Discussions at Cafe Infinity

Color Quotes - III

1. If there's any message to my work, it is ultimately that it's OK to be different, that it's good to be different, that we should question ourselves before we pass judgment on someone who looks different, behaves different, talks different, is a different color. - Johnny Depp

2. I can go completely berserk with the makeup, depending on the event. I'm currently in this very mod stage. I wear false lashes and color on my eyelids. I'm really liking shiny eyelids in copper, rose, gold, or silver. - Sharon Stone

3. It is by developing the individual that he is prepared for that wonderful manifestation of the human intelligence, which drawing constitutes. The ability to see reality in form, in color, in proportion, to be master of the movements of one's own hand - that is what is necessary. - Maria Montessori

4. I don't know if I have a favorite color. - Kate Middleton

5. I organize my denim, leather, and dresses by color, although my jeans are pretty much just black and gray. - Kate Moss

6. I've always eaten egg whites because when I was little, I didn't like the color yellow, so my mom would trick me into eating eggs by taking out the yolk. - Eva Longoria

7. 'The Color Purple' is the kind of character piece that a director like Sidney Lumet could do brilliantly with one hand tied behind his back. - Steven Spielberg

8. I love color. When I paint, I use a lot of color. I love art that has a vibrancy of color and compositions. I adore the Impressionists, and I'm influenced strongly by them as a self-taught artist. - Pierce Brosnan.

Jai Ganesh · Jokes

Q: What is a monkey's favorite cookie?
A: Chocolate chimp!
* * *
Q: What do you call a lamb covered in chocolate?
A: A Candy Baa.
* * *
Q: Did you hear about the love affair between Mr. Goodbar and Peppermint Patty?
A: They had a baby, Ruth.
* * *
Q: What do you call a womanizing chocolate?
A: A cad-bury.
* * *
Q: How do you know it's cold outside?
A: When you milk a brown cow you get chocolate ice cream!
* * *

Jai Ganesh · Science HQ

Coronary Arteries

Gist

Coronary arteries send blood to the heart muscle. All tissues in the body need oxygen-rich blood to function. The heart muscle also needs it. And oxygen-depleted blood must be carried away.

Coronary artery disease (CAD) is most commonly caused by atherosclerosis, the gradual buildup of plaque (fats, cholesterol, calcium) in the heart's arteries, leading to narrowing and reduced blood flow; key risk factors accelerating this process include smoking, high blood pressure, high cholesterol, diabetes, obesity, and lack of exercise.

Summary

A coronary artery is one of two blood vessels that branch from the aorta close to its point of departure from the heart and carry oxygen-rich blood to the heart muscle. Both arteries supply blood to the walls of both lower chambers (ventricles) and to the partition between the chambers. The right coronary artery supplies blood to the right upper chamber (atrium), while the left supplies the left atrium. Blockage of any branch of the coronary arteries causes death of a portion of the heart tissue when it is deprived of oxygen-rich blood

Details

The coronary arteries are the arterial blood vessels of coronary circulation, which transport oxygenated blood to the heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any other tissue or organ of the body.

The coronary arteries wrap around the entire heart. The two main branches are the left coronary artery and right coronary artery. The arteries can additionally be categorized based on the area of the heart for which they provide circulation. These categories are called epicardial (above the epicardium, or the outermost tissue of the heart) and microvascular (close to the endocardium, or the innermost tissue of the heart).

Reduced function of the coronary arteries can lead to decreased flow of oxygen and nutrients to the heart. Not only does this affect supply to the heart muscle itself, but it also can affect the ability of the heart to pump blood throughout the body. Therefore, any disorder or disease of the coronary arteries can have a serious impact on health, possibly leading to angina, a heart attack, and even death.

Structure

The coronary arteries are mainly composed of the left and right coronary arteries, both of which give off several branches.

* Aorta

** Left coronary artery

*** Left anterior descending artery
*** Left circumflex artery
*** Posterior descending artery
*** Ramus or intermediate artery

** Right coronary artery

*** Right marginal artery
*** Posterior descending artery

The left coronary artery arises from the aorta within the left cusp of the aortic valve and feeds blood to the left side of the heart. It branches into two arteries, the left anterior descending and the left circumflex. The left anterior descending artery perfuses the interventricular septum and anterior wall of the left ventricle. The left circumflex artery perfuses the left ventricular free wall. In approximately 33% of individuals, the left coronary artery gives rise to the posterior descending artery which perfuses the posterior and inferior walls of the left ventricle. Sometimes a third branch is formed at the fork between left anterior descending and left circumflex arteries, known as a ramus or intermediate artery.

The right coronary artery (RCA) originates within the right cusp of the aortic valve. It travels down the right coronary sulcus, towards the crux of the heart. The RCA primarily branches into the right marginal arteries, and, in 67% of individuals, gives place to the posterior descending artery. The right marginal arteries perfuse the right ventricle and the posterior descending artery perfuses the left ventricular posterior and inferior walls.

There is also the conus artery, which is only present in about 45 percent of the human population, and which provides collateral blood flow to the heart when the left anterior descending artery is occluded.

Clinical significance

Narrowing of the arteries can be caused by a process known as atherosclerosis (most common), arteriosclerosis, or arteriolosclerosis. This occurs when plaques (made up of deposits of cholesterol and other substances) build up over time in the walls of the arteries. Coronary artery disease (CAD) or ischemic heart disease are the terms used to describe narrowing of the coronary arteries.

As the disease progresses, plaque buildup can partially block blood flow to the heart muscle. Without enough blood supply (ischemia), the heart is unable to work properly, especially under increased stress. Stable angina is chest pain on exertion that improves with rest. Unstable angina is chest pain that can occur at rest, feels more severe, and/or last longer than stable angina. It is caused by more severe narrowing of the arteries.

A heart attack results from a sudden plaque rupture and formation of a thrombus (blood clot) that completely blocks blood flow to a portion of the heart, leading to tissue death (infarct).

CAD can also result in heart failure or arrhythmias. Heart failure is caused by chronic oxygen deprivation due to reduced blood flow, which weakens the heart over time. Arrhythmias are caused by inadequate blood supply to the heart that interferes with the heart's electric impulse.

The coronary arteries can constrict as a response to various stimuli, mostly chemical. This is known as a coronary reflex.

There is also a rare condition known as spontaneous coronary artery dissection, in which the wall of one of the coronary arteries tears, causing severe pain. Unlike CAD, spontaneous coronary artery dissection is not due to plaque buildup in arteries, and tends to occur in younger individuals, including women who have recently given birth or men who do intense exercise.

Coronary artery dominance is described as the coronary artery that give branches to supply the right posterior descending artery and supplies the inferior wall of the heart. In 80 to 85% of the population, the right coronary artery supplies the posterior descending artery, making it right heart dominant while in 7 to 13% of the population, the left coronary artery supplies the posterior descending artery, making it left heart dominant. In 7 to 8% of the population, both right and left coronary arteries supplies the posterior descending artery, making it right and left co-dominance. Narrowing of coronary arteries is more frequent in those who are left dominant when compared to those who have right dominant or co-dominant hearts.

Additional Information:

Anatomy and Function of the Coronary Arteries

Coronary arteries send blood to the heart muscle. All tissues in the body need oxygen-rich blood to function. The heart muscle also needs it. And oxygen-depleted blood must be carried away. The coronary arteries wrap around the outside of the heart. They send oxygen-rich blood into the heart's muscle tissues.

Two coronary arteries

The two main coronary arteries are:

* Left main coronary artery. This artery sends blood to the left side of the heart muscle. This includes the left ventricle and left atrium. It divides into these branches:

** Left anterior descending artery. This smaller artery branches off the left coronary artery. It sends blood to the front of the left side of the heart. It also helps send blood to the middle (septum) of the heart.

** Left circumflex artery. This artery also branches off the left coronary artery. It circles around the heart muscle. This artery sends blood to the outer side and back of the heart.

* Right coronary artery. This artery sends blood to the right side of the heart. This includes the right ventricle, the right atrium, and the SA (sinoatrial) and AV (atrioventricular) nodes. These nodes control the heart rhythm. The right coronary artery divides into smaller branches. One is the right posterior descending artery. The other is the acute marginal artery. It also helps send blood to the middle (septum) of the heart.

Problems with the coronary arteries

Since coronary arteries send blood to the heart muscle, any coronary artery problem can cause serious health problems. It reduces the flow of oxygen and nutrients to the heart muscle. This can lead to a heart attack and possibly death. The most common cause of heart disease is atherosclerosis. This is a buildup of plaque in the inner lining of an artery. It causes the artery to become narrow or blocked, so that less blood can get to the heart tissues.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#10715. What does the term in Biology Exocytosis mean?

#10716. What does the term in Biology External fertilization mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#5911. What does the noun leaven mean?

#5912. What does the noun lectern mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2552. What does the medical term Klatskin tumor (or hilar cholangiocarcinoma) mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9837.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6331.

Jai Ganesh · Exercises

Hi,

2688.

Jai Ganesh · Exercises

Hi,

2687.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9836.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6330.

Jai Ganesh · Exercises

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2687.

Jai Ganesh · Dark Discussions at Cafe Infinity

Color Quotes - II

1. To me, the good thing about living in L.A. is diversity in lifestyle choices, color, and religion. - Sandra Bullock

2. In inner-city, low-income communities of color, there's such a high correlation in terms of educational quality and success. - Bill Gates

3. She said the object and color in the materials around us actually have a physical effect on us, on how we feel. - Florence Nightingale

4. In too many communities, too many young men of color are left behind and seen only as objects of fear. Through initiatives like My Brother's Keeper, I'm personally committed to changing both perception and reality. - Barack Obama

5. Here's the thing: every office I've run for I was the first to win. First person of color. First woman. First woman of color. Every time. - Kamala Harris

6. I was always shocked when I went to the doctor's office and they did my X-ray and didn't find that I had eight more ribs than I should have or that my blood was the color green. - Nicolas Cage

7. The over-all point is that new technology will not necessarily replace old technology, but it will date it. By definition. Eventually, it will replace it. But it's like people who had black-and-white TVs when color came out. They eventually decided whether or not the new technology was worth the investment. - Steve Jobs

8. I believe there is complete equality between men and women. And I believe those passages in the New Testament, not by Jesus, but by Paul, that say women should not adorn themselves, they should always wear hats or color their hair in church - things like that - I think they are signs of the times and should not apply to modern-day life. - Jimmy Carter.

Jai Ganesh · Jokes

Q: What kind of candy is never on time?
A: ChocoLATE.
* * *
Q: What are the 4 major food groups? Pizza, Coffee, Chocolate and Tea.
* * *
Q: What do cannibals eat for dessert?
A: Chocolate covered aunts.
* * *
Q: How does the recipe for German chocolate cake begin?
A: First, invade ze kitchen.
* * *
Q: If Jake has 30 chocolate bars, and eats 25, what does he have?
A: Diabetes..... Jake has diabetes...
* * *

Jai Ganesh · This is Cool

2479) Greenland Shark

Greenland Shark

Gist

Greenland sharks (Somniosus microcephalus) are the longest-lived vertebrates on Earth, with lifespans estimated between 250 and 500 years. A 2016 study using radiocarbon dating of eye lens proteins indicated they live at least 272 years, with some individuals estimated to be roughly 400 years old, and possibly up to 512 years.

The Greenland shark has the longest known lifespan of all vertebrate species. It is estimated that the species has a lifespan of at least 272 years, with the oldest individual estimated to be 392 ± 120 years of age.

Summary

Greenland sharks are now the longest-living vertebrates known on Earth, scientists say.

Researchers used radiocarbon dating to determine the ages of 28 of the animals, and estimated that one female was about 400 years old.

The team found that the sharks grow at just 1cm a year, and reach sexual maturity at about the age of 150.

The research is published, external in the journal Science.

Lead author Julius Nielsen, a marine biologist from the University of Copenhagen, external, said: "We had our expectations that we were dealing with an unusual animal, but I think everyone doing this research was very surprised to learn the sharks were as old as they were."

The former vertebrate record-holder was a bowhead whale estimated to be 211 years old.

But if invertebrates are brought into the longevity competition, a 507-year-old clam called Ming, external holds the title of most aged animal.

Slow swimmers

Greenland sharks are huge beasts, that can grow up to 5m in length.

They can be found, swimming slowly, throughout the cold, deep waters of the North Atlantic.

With this leisurely pace of life and sluggish growth rate, the sharks were thought to live for a long time. But until now, determining any ages was difficult.

For some fish, scientists are able to examine ear bones called otoliths, which when sectioned, show a pattern of concentric rings that scientists can count as they would the rings in a tree.

Sharks are harder, but some species, such as the Great White, have calcified tissue that grows in layers on their back bones, that can also be used to age the animals.

"But the Greenland shark is a very, very soft shark - it has no hard body parts where growth layers are deposited. So it was believed that the age could not be investigated," Mr Nielsen told the BBC.

However the team found a clever way of working out the age.

"The Greenland shark's eye lens is composed of a specialised material - and it contains proteins that are metabolically inert," explained Mr Neilson.

"Which means after the proteins have been synthesised in the body, they are not renewed any more. So we can isolate the tissue that formed when the shark was a pup, and do radiocarbon dating."

The team looked at 28 sharks, most of which had died after being caught in fishing nets as by-catch.

Using this technique, they established that the largest shark - a 5m-long female - was extremely ancient.

Because radiocarbon dating does not produce exact dates, they believe that she could have been as "young" as 272 or as old as 512. But she was most likely somewhere in the middle, so about 400 years old.

It means she was born between the years of 1501 and 1744, but her most likely date of birth was in the 17th century.

"Even with the lowest part of this uncertainty, 272 years, even if that is the maximum age, it should still be considered the longest-living vertebrate," said Mr Nielsen.

Conversely, if her age is at the upper end of the scale, she will have out-lived Ming the clam - although her age has a greater probability of lying in the middle.

Details

The Greenland shark (Somniosus microcephalus), also known as the rubiks shark or gray shark, is a large shark of the family Somniosidae ("sleeper sharks"), closely related to the Pacific and southern sleeper sharks. Inhabiting the North Atlantic and Arctic Oceans, they are notable for their exceptional longevity, although they are poorly studied due to the depth and remoteness of their natural habitat.

Greenland sharks have the longest lifespan of any known vertebrate, estimated to be between 250 and 500 years. They are among the largest extant shark species, reaching a maximum confirmed length of 6.4 m (21 ft) and weighing more than 1,000 kg (2,200 lb). They reach sexual maturity around 150 years of age and their pups are born alive after an estimated gestation period of 8 to 18 years. The shark is a generalist feeder, consuming a variety of available foods, including carrion.

Greenland shark meat is toxic to mammals due to its high levels of trimethylamine N-oxide, although a treated form of it is eaten in Iceland as a delicacy known as kæstur hákarl. Because they live deep in remote parts of the northern oceans, Greenland sharks are not considered a threat to humans. A possible attack occurred in August 1936 on two British fishermen, but the species was never identified.

Description

The Greenland shark is one of the largest known existing species of shark, with adults growing to around 4 to 5 m (13 to 16 ft). The largest confirmed specimen measured up to 6.4 metres (21 ft) long and weighed around 1,023 kilograms (2,255 lb). The all-tackle International Game Fish Association (IGFA) record for this species is 775 kg (1,709 lb). It rivals the Pacific sleeper shark (possibly up to 7 m or 23 ft long) for the largest species in the family Somniosidae. Genetic data indicate that Greenland sharks diverged from ancestral sleeper sharks in the Canadian Arctic approximately 1–2.34 million years ago during the Pleistocene epoch, likely influenced by glacial fluctuations that periodically isolated marine populations. These ecological challenges may have driven physiological and metabolic adaptations for cold, deep waters.

The Greenland shark is a thickset species, with a short, rounded snout, small eyes, and small dorsal and pectoral fins. The gill openings are very small for the species's great size. Females are typically larger than males, with males reaching maturity at a smaller size than females.

Coloration can range from pale creamy-gray to blackish-brown and the body is typically uniform in color, though whitish spots or faint dark streaks are occasionally seen on the back.

The shark is often infested by the copepod Ommatokoita elongata, a crustacean that attaches itself to the shark's eyes. The copepod may display bioluminescence, thus attracting prey for the shark in a mutualistic relationship, but this hypothesis has not been verified. These parasites can cause multiple forms of damage to the sharks' eyes, such as ulceration, mineralization, and edema of the cornea, leading to almost complete blindness. This does not seem to reduce the life expectancy or predatory ability of Greenland sharks, due to their strong reliance on smell and hearing.

The genome of the Greenland shark was published in 2024. It is 6.45 billion base pairs in length.

Dentition

The dentition of a Greenland shark:

When feeding on large carcasses, the shark employs a rolling motion of its jaw. The 48 to 52 teeth of the upper jaw are very thin and pointed, lacking serrations. These upper jaw teeth act as an anchor, while the lower jaw proceeds to cut massive chunks out of the prey.

The 48 to 52 lower teeth interlock, are broad and square in shape, and contain short, smooth cusps that point outward. Teeth in the two halves of the lower jaw are strongly pitched in opposite directions.

Physiology

Like other Elasmobranchii, Greenland sharks have high concentrations of the two nitrogenous compounds urea and trimethylamine N-oxide (TMAO) in their tissues, which increase their buoyancy and function as osmoprotectants. TMAO also counteracts the protein-destabilizing tendencies of urea and deep-water pressure. Its presence in the tissues of both elasmobranch and teleost fish has been found to increase with depth.

The blood of Greenland sharks contains three major types of hemoglobin, made up of two copies of α globin combined with two copies of three very similar β subunits. These three types show very similar oxygenation and carbonylation properties, which are unaffected by urea, an important compound in marine Elasmobranchii physiology. They display identical electronic absorption and resonance in Raman spectroscopy, indicating that their heme-pocket structures are identical or highly similar. The hemoglobins also have a lower affinity for oxygen compared to those of temperate sharks. These characteristics are believed to be adaptations to living at great depths.

When hoisted upon deck, it beats so violently with its tail, that it is dangerous to be near it, and the seamen generally dispatch it, without much loss of time. The pieces that are cut off exhibit a contraction of their muscular fibres for some time after life is extinct. It is, therefore, extremely difficult to kill, and unsafe to trust the hand within its mouth, even when the head is cut off. And, if we are to believe Crantz, this motion is to be observed three days after, if the part is trod on or struck.

— Henry William Dewhurst, The Natural History of the Order Cetacea (1834).

Additional Information

Greenland shark, (Somniosus microcephalus), member of the sleeper shark family Somniosidae (order Squaliformes, which also includes the dogfish family, Squalidae) also known for being the world’s longest-lived vertebrate. The species is primarily found in the cold-water environments of the Arctic Ocean and North Atlantic, from Baffin Bay eastward to the Barents Sea, but its range also extends southward to the North Sea and the waters adjacent to the Eastern Seaboard of the United States. Bulky, with a rounded snout, small fins relative to body size, and gray to brown coloration, Greenland sharks are similar to spiny dogfish (Squalus acanthias), except that they lack a spine in front of the second dorsal fin and usually the one on the first dorsal fin.

Natural history

The Greenland shark is one of the largest cartilaginous fishes. It can reach a length of 7 metres (23 feet) and a weight of 1,025 kg (2,260 pounds) when fully grown, but most are between 2 and 4 metres (6.5 and 13 feet). Little is known, however, about how the species reproduces. Females are thought to reach sexual maturity when they surpass the 4-metre (13-foot) mark in length, which takes approximately 150 years to achieve. They are ovoviviparous (that is, eggs are retained within the body until they hatch) and produce an average of 10 offspring at a time. The type, amount, and duration of parental care the young receive are unknown, but scientists speculate that, like other shark species, Greenland sharks are independent from birth. No other vertebrate known has a life span as long as this species, and a 2016 study that used radiocarbon dating to examine isotopes in the shark’s eye-lens nuclei suggested that the oldest Greenland sharks may be more than 500 years old. Using this technique, scientists estimated that the largest Greenland shark in the study was likely between 272 and 512 years old.

Greenland sharks are rarely encountered by humans. They are thought to prefer colder, deeper environments but may be found anywhere between the sea surface and depths of 2,200 meters (about 7,200 feet). Greenland sharks are slow-moving, typically swimming at rates of less than 3 km (about 1.9 miles) per hour.

They are carnivorous, and their diet is often made up of several different types of fishes, including smaller sharks, eels, flounders, and sculpins. Crustaceans, seabirds, and carrion—as well as terrestrial mammals (such as horses and reindeer) that likely fell through the ice—have been found in stomach analyses of the species. Greenland sharks are not considered dangerous to humans, in part because they live in regions where people do not typically swim; the only known report of a possible attack by a Greenland shark on a person dates to 1859.

Conservation status

The International Union for Conservation of Nature has classified the Greenland shark as a vulnerable species since 2020. The fish was valued historically for its liver oil; about 114 litres (30 gallons) of liver oil can be obtained from a large specimen (see also fish oil). (Although the flesh of the Greenland shark may be eaten, it is toxic unless properly cleaned and dried or repeatedly boiled prior to consumption.) They were fished commercially from the 19th century until 1960. Norway persecuted Greenland sharks during the 1970s, because they were considered to be a nuisance that threatened other fisheries. In the early 1900s as many as 30,000 Greenland sharks were caught a year. In the present day the annual take is far smaller; small-scale subsistence fisheries in the Arctic harvest fewer than 100 individuals annually, and roughly 1,200 are caught accidentally in fishing trawls.

Jai Ganesh · Science HQ

Pia Mater

Gist

Pia mater, often referred to as simply the pia, is the delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord. Pia mater is medieval Latin meaning "tender mother". The other two meningeal membranes are the dura mater and the arachnoid mater.

The pia mater is the innermost layer of the meninges and together with the arachnoid mater is referred to as the leptomeninges. It is closely related to the surface of the brain and unlike the arachnoid mater extends into the sulci

The pia mater is the innermost layer of the meninges and together with the arachnoid mater is referred to as the leptomeninges. It is closely related to the surface of the brain and unlike the arachnoid mater extends into the sulci.

Summary

Pia is the innermost layer of the meninges, the connective tissue layers that surround the central nervous system. It is a thin, transparent, delicate layer that hugs the surface of the brain and spinal cord, closely following its contours. The pia and arachnoid layers of the meninges are collectively called the leptomeninges. Located between these two layers is the cerebrospinal fluid containing subarachnoid space.

The pia is highly vascularized by a network of fine blood vessels. In the cranium, the pia extends for a short distance along the surface of blood vessels as they travel to and from the meninges to enter and exit the cerebral cortex. This pia extension is called a pial coat. Similar extensions are seen in the spinal cord where the pia follows spinal nerves and spinal blood vessels for a short distance as they travel away from the central cord. Fingers of vascularized pia covered by epithelial cells form invaginations into ventricles called choroid plexuses. Choroid plexuses function to secrete cerebrospinal fluid.

In the spinal cord, the pia forms tiny ligaments called the denticulate ligaments. These ligaments suspend the spinal cord within the dural sac. The inferior most aspect of the spinal meninges is anchored to the coccyx by a thin strand called the filum terminale. This filum has internal and external parts, the internal being formed by a strand of pia.

Details

Pia mater, often referred to as simply the pia, is the delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord. Pia mater is medieval Latin meaning "tender mother". The other two meningeal membranes are the dura mater and the arachnoid mater. Both the pia and arachnoid mater are derivatives of the neural crest while the dura is derived from embryonic mesoderm. The pia mater is a thin fibrous tissue that is permeable to water and small solutes. The pia mater allows blood vessels to pass through and nourish the brain. The perivascular space between blood vessels and pia mater is proposed to be part of a pseudolymphatic system for the brain (glymphatic system). When the pia mater becomes irritated and inflamed the result is meningitis.

Structure

Pia mater is the thin, translucent, mesh-like meningeal envelope, spanning nearly the entire surface of the brain. It is absent only at the natural openings between the ventricles, the median aperture, and the lateral aperture. The pia firmly adheres to the surface of the brain and loosely connects to the arachnoid layer. Because of this continuum, the layers are often referred to as the pia arachnoid or leptomeninges. A subarachnoid space exists between the arachnoid layer and the pia, into which the choroid plexus releases and maintains the cerebrospinal fluid (CSF). The subarachnoid space contains trabeculae, or fibrous filaments, that connect and bring stability to the two layers, allowing for the appropriate protection from and movement of the proteins, electrolytes, ions, and glucose contained within the CSF.

The thin membrane is composed of fibrous connective tissue, which is covered by a sheet of flat cells impermeable to fluid on its outer surface. A network of blood vessels travels to the brain and spinal cord by interlacing through the pia membrane. These capillaries are responsible for nourishing the brain. This vascular membrane is held together by areolar tissue covered by mesothelial cells from the delicate strands of connective tissue called the arachnoid trabeculae. In the perivascular spaces, the pia mater begins as mesothelial lining on the outer surface, but the cells then fade to be replaced by neuroglia elements.

Although the pia mater is primarily structurally similar throughout, it spans both the spinal cord's neural tissue and runs down the fissures of the cerebral cortex in the brain. It is often broken down into two categories, the cranial pia mater (pia mater encephali) and the spinal pia mater (pia mater spinalis).

Cranial pia mater

The section of the pia mater enveloping the brain is known as the cranial pia mater. It is anchored to the brain by the processes of astrocytes, which are glial cells responsible for many functions, including maintenance of the extracellular space. The cranial pia mater joins with the ependyma, which lines the cerebral ventricles to form choroid plexuses that produce cerebrospinal fluid. Together with the other meningeal layers, the function of the pia mater is to protect the central nervous system by containing the cerebrospinal fluid, which cushions the brain and spine.

The cranial pia mater covers the surface of the brain. This layer goes in between the cerebral gyri and cerebellar laminae, folding inward to create the tela chorioidea of the third ventricle and the choroid plexuses of the lateral and third ventricles. At the level of the cerebellum, the pia mater membrane is more fragile due to the length of blood vessels as well as decreased connection to the cerebral cortex.

Spinal pia mater

The spinal pia mater closely follows and encloses the curves of the spinal cord, and is attached to it through a connection to the anterior fissure. The pia mater attaches to the dura mater through 21 pairs of denticulate ligaments that pass through the arachnoid mater and dura mater of the spinal cord. These denticular ligaments help to anchor the spinal cord and prevent side to side movement, providing stability. The membrane in this area is much thicker than the cranial pia mater, due to the two-layer composition of the pia membrane. The outer layer, which is made up of mostly connective tissue, is responsible for this thickness. Between the two layers are spaces which exchange information with the subarachnoid cavity as well as blood vessels. At the point where the pia mater reaches the conus medullaris or medullary cone at the end of the spinal cord, the membrane extends as a thin filament called the filum terminale or terminal filum, contained within the lumbar cistern. This filament eventually blends with the dura mater and extends as far as the coccyx, or tailbone. It then fuses with the periosteum, a membrane found at the surface of all bones, and forms the coccygeal ligament. There it is called the central ligament and assists with movements of the trunk of the body.

Additional Information

The pia mater is the delicate innermost layer of the meninges, directly enveloping the brain and spinal cord and adhering closely to the contours of the central nervous system (CNS) surface, including the gyri and sulci of the brain and the external surfaces of the spinal cord. It is composed of connective tissue, including collagenous, reticular, and elastic fibers, and contains numerous blood vessels that penetrate the CNS parenchyma. The pia mater is covered superficially by a single layer of flattened mesothelial cells and is anchored to the underlying cortex by a glial membrane.

This meningeal layer plays a significant role in maintaining the neural microenvironment through its involvement in neurovascular interactions. It forms sheaths around blood vessels entering and exiting the CNS, creating perivascular spaces known as Virchow–Robin spaces. These spaces are important for cerebrospinal fluid (CSF) absorption and clearance and are thought to communicate with the subpial space. The pia mater is continuous with the glia limitans, a thin subpial layer comprised of astrocyte endfeet, which insulates the CNS from substances present in the vascular and subarachnoid compartments. The subarachnoid space, located between the arachnoid mater and the pia mater, contains CSF, which circulates and provides mechanical protection, nutrient delivery, and waste removal for the CNS.

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Jai Ganesh · This is Cool

Tuvalu

Gist

Tuvalu is a low-lying Polynesian island nation in the west-central Pacific, known for its nine coral atolls and islands, rich marine life, and significant threat from rising sea levels due to climate change. An independent Commonwealth realm, it's economically reliant on fishing licenses, remittances, stamps, the ".tv" domain, and aid, with its capital and main government hub on Funafuti. The culture emphasizes strong community ties, while its low elevation makes it a focal point for global climate action discussions.

Nobody visits Tuvalu much because it's incredibly remote, hard to reach due to limited flights, lacks large-scale tourist resorts, and faces serious threats from rising sea levels and climate change, despite its pristine beauty, making it the world's least-visited country. Its tiny size, scarce infrastructure, and isolation combine to make it logistically challenging and expensive for most tourists to access.

Summary

Tuvalu is an island country in the Polynesian sub-region of Oceania in the Pacific Ocean, about midway between Hawaii and Australia. It lies east-northeast of the Santa Cruz Islands (which belong to the Solomon Islands), northeast of Vanuatu, southeast of Nauru, south of Kiribati, west of Tokelau, northwest of Samoa and Wallis and Futuna, and north of Fiji.

Tuvalu is composed of three reef islands and six atolls spread out between the latitude of 5° and 10° south and between the longitude of 176° and 180°. They lie west of the International Date Line. The 2022 census determined that Tuvalu had a population of 10,643, making it the 194th most populous country, exceeding only Niue and the Vatican City in population. Tuvalu's total land area is 25.14 square kilometres (9.71 sq mi).

The first inhabitants of Tuvalu were Polynesians arriving as part of the migration of Polynesians into the Pacific that began about three thousand years ago. Long before European contact with the Pacific islands, Polynesians frequently voyaged using canoes between the islands. Polynesian navigation skills enabled them to make elaborately planned journeys in either double-hulled sailing canoes or outrigger canoes. Scholars believe that the Polynesians spread out from Samoa and Tonga into the Tuvaluan atolls, which then served as a stepping stone for further migration into the Polynesian outliers in Melanesia and Micronesia.

In 1568, Spanish explorer and cartographer Álvaro de Mendaña became the first European known to sail through the archipelago, sighting the island of Nui during an expedition he was making in search of Terra Australis. The island of Funafuti, currently serving as the capital, was named Ellice's Island in 1819. Later, the whole group was named Ellice Islands by English hydrographer Alexander George Findlay. In the late 19th century, Great Britain claimed control over the Ellice Islands, designating them as within their sphere of influence. Between 9 and 16 October 1892, Captain Herbert Gibson of HMS Curacoa declared each of the Ellice Islands a British protectorate. Britain assigned a resident commissioner to administer the Ellice Islands as part of the British Western Pacific Territories (BWPT). From 1916 to 1975, they were managed as part of the Gilbert and Ellice Islands colony.

A referendum was held in 1974 to determine whether the Gilbert Islands and Ellice Islands should each have their own administration. As a result, the Gilbert and Ellice Islands colony legally ceased to exist on 1 October 1975; on 1 January 1976, the old administration was officially separated, and two separate British colonies, Kiribati and Tuvalu, were formed. On 1 October 1978, Tuvalu became fully independent as a sovereign state within the Commonwealth, and is a constitutional monarchy with Charles III as King of Tuvalu. On 5 September 2000, Tuvalu became the 189th member of the United Nations.

The islands do not have a significant amount of soil, so the country relies heavily on imports and fishing for food. Licensing fishing permits to international companies, grants and aid projects, and remittances to their families from Tuvaluan seafarers who work on cargo ships are important parts of the economy. Because it is a low-lying island nation, Tuvalu is extremely vulnerable to sea level rise due to climate change. It is active in international climate negotiations as part of the Alliance of Small Island States.

Details

Tuvalu, country in the west-central Pacific Ocean. It is composed of nine small coral islands scattered in a chain lying approximately northwest to southeast over a distance of some 420 miles (676 km).

The de facto capital is the village of Vaiaku, where most government offices are located. It is on Fongafale islet, a constituent part of Funafuti Atoll. Together with what is now Kiribati (formerly the Gilbert Islands), Tuvalu formed the British Gilbert and Ellice Islands Colony before separately gaining its independence in 1978.

Land

The group includes both atolls and reef islands. The atolls—Nanumea, Nui, Nukufetau, Funafuti, and Nukulaelae—have islets encircling a shallow lagoon; the reef islands—Nanumanga, Niutao, Vaitupu, and Niulakita—are compact with a fringing reef. The islands are low-lying, most being 13 to 16 feet (4 to 5 meters) above sea level. There are no rivers; rain catchment and wells provide the only fresh water. Rainfall averages 100 inches (2,500 mm) in the north and 125 inches (3,175 mm) in the south. The prevailing winds are southeast trades; westerly storms occur from November to February. Daytime temperatures range from 80 to 85 °F (27 to 29 °C).

Because the soils are porous, agriculture is limited. Coconut palms thrive, and breadfruit trees, pandanus, taro, and bananas are grown. Pigs and chickens are raised, and seabirds, fish, and shellfish are caught for food. The islands increasingly depend on imported food.

People

The Tuvaluans are Polynesian, and their language, Tuvaluan, is closely related to Samoan. Nui, however, was heavily settled in prehistoric times by Micronesians from the Gilbert Islands (now Kiribati). English is taught in the schools and widely used. The vast majority of the population belongs to the Church of Tuvalu (the former Ellice Islands Protestant Church).

Although most people live on the outer islands in extended family households clustered into villages, about one-third of the population lives on Funafuti, the center of government and commerce. Population growth has been slowed by family planning; life expectancy at birth is about 60 years. About 10 percent of the population lives overseas, either pursuing education, working in the Nauru phosphate industry, or working on merchant ships.

Economy

Most Tuvaluans are subsistence farmers and are aided by remittances from relatives working overseas. A small quantity of copra is produced for export, the sale of stamps accounts for modest earnings, and fees are collected from foreign fishing fleets, but the country depends heavily on foreign aid. It imports most of its food, fuel, and manufactured goods. Fiji, Australia, New Zealand, and Japan are among the country’s major trade partners. Retailing is handled by community-based cooperative societies. Tuvalu uses Australian currency but also issues its own coinage. There is a single bank, a joint government-commercial venture.

Tuvalu has air links with Kiribati and Fiji; for international shipping, it depends on irregular regional services. Seaplanes have been used for interisland travel, but generally the outer islands depend on a single government vessel. Motorcycles are common on Funafuti, but there are few automobiles.

Government and society

Tuvalu is a constitutional monarchy within the Commonwealth, with the British monarch (through a governor-general) as head of state. The government is a parliamentary democracy with a unicameral legislature elected by universal adult suffrage. There are no political parties: the prime minister is chosen by and from the legislature. Tuvalu is a member of the South Pacific Forum.

The government provides universal primary education and, under a joint arrangement with the Church of Tuvalu, secondary education to school certificate level for selected pupils. A few are sent overseas for further education and training. Medical facilities are centralized on Funafuti, but all other islands have clinics with trained medical staff.

Cultural life

The Tuvaluan lifestyle has been Westernized to an extent, but Western-style amenities are few. Only Funafuti has a regular electricity supply; the government publishes a brief news sheet, but there is no newspaper; a few motion pictures are shown; satellite television service is available only by subscription; and there is only a single radio station. Most Tuvaluans live in villages of a few hundred people, tend their gardens, and fish from handcrafted canoes. Traditional music and dancing still enjoy a strong following, along with Western forms. Volleyball, football (soccer), and cricket are popular. Tuvaluan life, despite modernization, still rests on a firm traditional base that emphasizes the importance of community consensus and identity.

History of Tuvalu

The first settlers were from Samoa and probably arrived in the 14th century ad. Smaller numbers subsequently arrived from Tonga, the northern Cook Islands, Rotuma, and the Gilbert Islands. Niulakita, the smallest and southernmost island, was uninhabited before European contact; the other islands were settled by the 18th century, giving rise to the name Tuvalu, or “Cluster of Eight.”

Europeans first discovered the islands in the 16th century through the voyages of Álvaro de Mendaña de Neira, but it was only from the 1820s, with visits by whalers and traders, that they were reliably placed on European charts. In 1863 labor recruiters from Peru kidnapped some 400 people, mostly from Nukulaelae and Funafuti, reducing the population of the group to less than 2,500. A few were later recruited for plantations in Queensland, Australia, as well as in Fiji, Samoa, and Hawaii. Concern over labor recruiting and a desire for protection helps to explain the enthusiastic response to Samoan pastors of the London Missionary Society who arrived in the 1860s. By 1900, Protestant Christianity was firmly established.

With imperial expansion the group, then known as the Ellice Islands, became a British protectorate in 1892 and part of the Gilbert and Ellice Islands Colony in 1916. There was a gradual expansion of government services, but most administration was through island governments supervised by a single district officer based in Funafuti. Ellice Islanders sought education and employment at the colonial capital in the Gilbert group or in the phosphate industry at Banaba or Nauru. During World War II, U.S. forces were based on Nanumea, Nukufetau, and Funafuti, but hostilities did not reach the group.

From the 1960s, racial tension and rivalries over employment emerged between Gilbertese and Ellice Islanders. Ellice Islanders’ demands for secession resulted in a referendum in 1974, transition to separate colonial status between October 1975 and January 1976, and independence as Tuvalu in 1978. After independence the main priorities were to establish the infrastructure for a separate, if small, nation, and to seek foreign assistance to match political independence with economic viability.

Additional Information

Tuvalu is a small island nation located in the Pacific Ocean, composed of nine islands and atolls. It is known for its stunning natural beauty, including pristine beaches and rich marine biodiversity. The country has a population of around 11,000 people, who primarily engage in subsistence farming and fishing. Tuvalu faces significant challenges related to climate change, particularly rising sea levels, which threaten its very existence and have garnered international attention. The culture of Tuvalu is deeply rooted in Polynesian traditions, with a strong emphasis on community and family ties. The official languages are Tuvaluan and English, reflecting its colonial history and modern connections. Economically, Tuvalu relies on fishing, remittances from citizens abroad, and tourism, though it remains one of the least developed countries globally. Its unique cultural heritage, combined with pressing environmental concerns, makes Tuvalu a focal point for discussions on sustainability and climate action.

Tuvalu is a small independent island nation in the South Pacific (Oceania) consisting of nine low-lying coral atolls and reef islands. With a population of roughly 10,600 as of 2026, it is one of the world's smallest nations, heavily reliant on fishing, tourism, foreign aid, and the .tv internet domain. The capital is Funafuti, and the nation faces severe climate change threats.

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Jai Ganesh · Dark Discussions at Cafe Infinity

Color Quotes - I

1. Clouds come floating into my life, no longer to carry rain or usher storm, but to add color to my sunset sky. - Rabindranath Tagore

2. Design is the fundamental soul of a man-made creation that ends up expressing itself in successive outer layers of the product or service. The iMac is not just the color or translucence or the shape of the shell. The essence of the iMac is to be the finest possible consumer computer in which each element plays together. - Steve Jobs

3. Until justice is blind to color, until education is unaware of race, until opportunity is unconcerned with the color of men's skins, emancipation will be a proclamation but not a fact. - Lyndon B. Johnson

4. My favorite color is black. - Johnny Depp

5. I have dreamed in my life, dreams that have stayed with me ever after, and changed my ideas; they have gone through and through me, like wine through water, and altered the color of my mind. - Emily Bronte

6. If you're white and you're wrong, then you're wrong; if you're black and you're wrong, you're wrong. People are people. Black, blue, pink, green - God make no rules about color; only society make rules where my people suffer, and that why we must have redemption and redemption now. - Bob Marley

7. If they ever do my life story, whoever plays me needs lots of hair color and high heels. - Charlize Theron

8. Hating people because of their color is wrong. And it doesn't matter which color does the hating. It's just plain wrong. - Muhammad Ali.

Jai Ganesh · Jokes

Q: What does a cherry say at the end of the year?
A: Cherry Christmas.
* * *
Q: What did the cherry say to the cherry pie?
A: "You've got some crust."
* * *
Q: What happens when a cherry tree grows up?
A: It blossoms.
* * *
Q: What do you say when someone offers you some pie?
A: Thank you cherry much.
* * *
Q: What did Jani Lane tell Tommy Lee?
A: She's my cherry pie....
* * *
Q: What do you get when you cross a talk show host and a fruit?
A: Cherry Shepherd.
* * *

Jai Ganesh · This is Cool

2478) Channel Tunnel

Channel Tunnel

Gist

The Channel Tunnel (often called the 'Chunnel' for short) is an undersea tunnel linking southern England and northern France. It is operated by the company Getlink, who also run a railway shuttle (Le Shuttle) between Folkestone and Calais, carrying passengers in cars, vans and other vehicles.

Which country owns the Channel tunnel?

To be specific, LeShuttle is operated by Getlink, the company which owns and operates the Channel Tunnel, the infrastructure connecting the UK with France. Eurostar is a customer of Getlink and runs its passenger trains through the tunnel.

How long are you underwater in the chunnel?

How long are you underwater on the Eurostar? It takes around 35 minutes for the Eurostar to cross the 23-mile underwater stretch of the Channel Tunnel.

Summary

The Channel Tunnel (French: Tunnel sous la Manche, sometimes referred to as the Chunnel) is a 50.46-kilometre (31.35-mile) railway tunnel beneath the English Channel that connects Folkestone in the United Kingdom with Coquelles in northern France. Opened in 1994, it remains the only fixed link between Great Britain and the European mainland.

The tunnel has the longest underwater section of any tunnel in the world, at 37.9 km (23.5 miles), reaching a depth of 75 m (246 ft) below sea level and runs, on average, 45 m (148 ft) below the seabed. It is the third-longest railway tunnel in the world. Although the tunnel was designed for speeds up to 200 km/h (120 mph), trains are limited to a maximum speed of 160 km/h (99 mph) for safety reasons. It connects to high-speed railway lines on either end: the LGV Nord in France and High Speed 1 in the United Kingdom.

The tunnel is operated by Getlink (formerly Eurotunnel) and is used by Eurostar high-speed passenger trains, LeShuttle services for road vehicles, and freight trains. In 2017, Eurostar trains carried 10.3 million passengers, freight trains transported 1.2 million tonnes (2.6 billion pounds) of freight, and LeShuttle trains moved 10.4 million passengers in 2.6 million cars and 51,000 coaches, and 1.6 million heavy goods vehicles carrying 21.3 million tonnes (47 billion pounds) of freight. That compares with 11.7 million passengers, 2.2 million cars, and 2.6 million heavy goods vehicles transported by sea through the Port of Dover.

Proposals for a cross-Channel tunnel date back as early as 1802, but concerns over national security delayed development. The modern project was initiated by Eurotunnel in 1988 and completed in 1994, at a final cost of £4.65 billion (equivalent to £11.7 billion in 2023). An engineering marvel, the Channel Tunnel was, at the time of its opening, by far the longest tunnel in Europe, and has only been surpassed by the Gotthard Base Tunnel in Switzerland. However, despite its engineering significance, several economic assessments have found that it has had only a limited positive economic impact on the British economy. Additionally, the tunnel has also experienced occasional service disruptions due to technical faults, fires, severe weather, and unauthorised access by migrants around Calais seeking entry to the United Kingdom.

Details

The Channel Tunnel (often called the 'Chunnel' for short) is an undersea tunnel linking southern England and northern France. It is operated by the company Getlink, who also run a railway shuttle (Le Shuttle) between Folkestone and Calais, carrying passengers in cars, vans and other vehicles.

Eurostar is a totally separate company and is Getlink’s biggest customer, running high-speed passenger services through the Channel Tunnel between London and a number of other European cities on the continent, including Paris, Brussels, Lille, Amsterdam and Rotterdam.

The Chunnel actually comprises three tunnels: two rail tunnels, used for freight and passenger trains, and a service tunnel.

How long is the Channel Tunnel?

The Channel Tunnel is 31.5 miles long or 50.45 km. That's the equivalent of 169 Eiffel Towers stacked on top of each other.

23.5 miles (37.9 km) of the Channel Tunnel is under the English Channel, making it the world's longest undersea tunnel.

What year did the Channel Tunnel open?

The idea of a tunnel under the Channel was first proposed in 1802 but construction wasn't started until 1988. It was completed in 1993, and Eurostar services started in November 1994.

What does the Eurotunnel look like underwater?

This may be a disappointing answer, but you can't actually see the sea from the Eurostar. When you go through the tunnel and look out of the window, all you can see is your reflection in the glass because it's quite dark outside. You can catch glimpses of the walls of the tunnel, of course, which are made of reinforced concrete.

Where is the Channel Tunnel?

The Channel Tunnel runs between Calais in northern France and Folkestone in south Kent. Vehicle traffic for Le Shuttle gets on in Calais and gets off in Folkestone. Calais is about three hour's drive from Paris and Folkestone is about an hour and a half's drive from London.

Our passenger-only Eurostar trains leave from St Pancras International station in London and go directly to the centre of Paris, Brussels and other Eurostar destinations in Europe.

How deep is the Channel Tunnel?

At its deepest, the tunnel is 75 metres (246 feet) below the sea level. That's the same as 107 baguettes balancing on top of each other.

The English Channel is much deeper than the tunnel, with its deepest point measuring 175 meters (574 feet) below sea level.

How was the Channel Tunnel built?

The Channel Tunnel is made of three separate tunnels running parallel to each other. One train tunnel running south (UK to France), one train tunnel running north (France to UK) and one service tunnel. All three tunnels were drilled below the seabed and link Folkestone in Kent to Coquelles in Pas-de-Calais.

However, the idea of connecting the UK and France by tunnel is much older than people think – dating back to the early 1800s when its supporters included Napoleon Bonaparte.

Work on experimental tunnels started back in 1880 at Abbot’s Cliff near Folkestone, Kent. Many of the workers used hand tools, but a state-of-the-art boring machine was also used. Work was eventually abandoned until construction on the tunnel as we now know it began again in 1988.

Frequently Asked Questions:

Thinking of hopping on Eurostar for your next European adventure? Got a couple of need-to-know questions before you book your trip? Here we’ve answered a selection of the most frequently asked questions from our customers.

Who can travel through the Channel Tunnel?

Foot passengers can travel with Eurostar, between our UK stations London St Pancras International and our stations on the continent . People who want to travel with their own vehicle or on a coach can use the Eurotunnel Le Shuttle between Folkestone and Calais. Before travelling with either Eurostar or Eurotunnel you will need to go through security, border and ticket checks before going through the Tunnel.

How much did it cost to build the Channel Tunnel?

It took just under six years and 13,000 workers to build the Channel Tunnel. The total cost came at an eye-watering £4.65 billion which would be the equivalent of £12 billion in today's money.

Why travel with Eurostar rather than drive?

* Avoid the stress of driving, with direct high-speed journeys to top destinations, from city centre to city centre.
* Great value fares with no additional costs like fuel, road tolls and parking.
* Simple connections with other rail services in Europe, allowing you to go beyond our direct destinations on a single booking.
* Travel in style on our comfortable trains, including our new, state-of-the art trains with wi-fi.

How fast does the Eurostar go?

The Eurostar travels through the Channel Tunnel at a speed of 100 miles per hour (160kph) although when the train is outside the tunnel it reaches speed of 186 miles per hour (300 kph).

Additional Information

Channel Tunnel, rail tunnel between England and France that runs beneath the English Channel. The Channel Tunnel, 50 km (31 miles) long, consists of three tunnels: two for rail traffic and a central tunnel for services and security. The tunnel runs between Folkestone, England, and Sangatte (near Calais), France, and is used for both freight and passenger traffic. Passengers can travel either by ordinary rail coach or within their own motor vehicles, which are loaded onto special railcars. Trains can travel through the tunnel at speeds as high as 160 km (100 miles) per hour; the trip takes about 35 minutes. It has the longest undersea portion of any tunnel in the world (37.8 km [23.5 miles]).

The often-considered idea of constructing a tunnel under the English Channel was revived in 1986 by the United Kingdom and France. A rail tunnel was chosen over proposals for a very long suspension bridge, a bridge-and-tunnel link, and a combined rail-and-road link, and the project was privately financed by a consortium of British and French corporations and banks; the Anglo-French company operating the tunnel is called Eurotunnel. Digging began on both sides of the Strait of Dover in 1987–88 and was completed in 1991. The tunnel was officially opened on May 6, 1994.

In 2007 the Channel Tunnel Rail Link (CTRL), also called High Speed 1, was opened to connect the Channel Tunnel with London, facilitating even greater movement of international passenger traffic between mainland Europe and the United Kingdom. The high-speed railway runs 108 km (67 miles) and crosses under the Thames. Its trains can reach speeds of up to 300 km (186 miles) per hour.

In June–July 2015 the problem of migrants—many of them from eastern Africa—sneaking aboard vehicles on trains in an attempt to immigrate to the United Kingdom reached crisis proportions. During that period at least nine individuals were killed while trying to make their way to England via the tunnel. The United Kingdom and France stepped up security measures to try to deter migrants from attempting the crossing.

Jai Ganesh · Science HQ

Gilbert's Syndrome

Gist

Gilbert syndrome is caused by a modified gene someone inherits from their parents. This gene usually controls an enzyme that helps break down bilirubin in the liver. When someone has this ineffective gene, their blood contains too much bilirubin. This is because the body isn't producing enough of the enzyme.

Gilbert Syndrome diagnosis involves blood tests showing elevated unconjugated bilirubin with normal liver function tests (LFTs) and a complete blood count (CBC) to rule out other liver or blood conditions, often discovered incidentally in teens/young adults experiencing mild jaundice. Genetic testing for the UGT1A1 gene mutation can confirm it, but isn't always necessary, as the pattern of normal liver function with elevated bilirubin is usually sufficient for a confirmed diagnosis.

Summary

Gilbert's syndrome (GS) is a syndrome in which the liver of affected individuals processes bilirubin more slowly than the majority, resulting in higher levels in the blood. Many people never have symptoms. Occasionally jaundice (a yellowing of the skin or whites of the eyes) may occur.

Gilbert syndrome is due to a genetic variant in the UGT1A1 gene, which results in decreased activity of the bilirubin uridine diphosphate glucuronosyltransferase enzyme. It is typically inherited in an autosomal recessive pattern and occasionally in an autosomal dominant pattern depending on the type of variant. Episodes of jaundice may be triggered by stress such as exercise, menstruation, or not eating. Diagnosis is based on elevated levels of unconjugated bilirubin in the blood without signs of liver problems or red blood cell breakdown.

Typically, no treatment is needed. Phenobarbital aids in the conjugation of bilirubin and can be prescribed if jaundice becomes significant. Gilbert syndrome is associated with decreased cardiovascular health risks but increased risks of some cancers and gallstones. Gilbert syndrome affects about 5% of people in the United States. Males are more often diagnosed than females. It is often not noticed until late childhood to early adulthood. The condition was first described in 1901 by Augustin Nicolas Gilbert.

Details

People with Gilbert's syndrome inherit a mutated gene that affects the liver’s ability to process bilirubin, a waste product that forms during the breakdown of old red blood cells. Jaundice (yellowish skin and eyes) occurs when too much bilirubin builds up in blood. Because this liver disease doesn’t cause serious problems, treatment isn’t necessary.

Overview:

What is Gilbert's syndrome?

Gilbert's syndrome is an inherited (genetic) liver disorder that affects the body’s ability to process bilirubin. Bilirubin is yellow liquid waste that occurs naturally as the body breaks down old red blood cells.

People with Gilbert's syndrome don’t produce enough liver enzymes to keep bilirubin at a normal level. As a result, excess bilirubin builds up in the body. Excess bilirubin is known as hyperbilirubinemia.

What is bilirubin?

Bilirubin is found in bile, a digestive liquid produced by the liver that helps the body absorb fat. Your liver is part of the digestive system. It filters toxins from blood, digests fats and stores glucose (a blood sugar) as glycogen to use for energy.

How common is Gilbert's syndrome?

An estimated 3% to 7% of Americans have Gilbert's syndrome. This type of liver disease is more common in males than in females. It affects all ages, races and ethnicities.

Who might have Gilbert's syndrome?

Gilbert's syndrome is genetic, meaning it’s passed down from parent to child through a change, or mutation, in a gene. People with Gilbert's syndrome inherit a mutated UGT1A1 gene.

Symptoms and Causes:

What causes Gilbert's syndrome?

A healthy UGT1A1 gene makes liver enzymes that break down bilirubin and remove it from the body. People with a mutated UGT1A1 gene only make about 30% of the enzymes they need. As a result, bilirubin doesn’t move into bile the way it should. The excess bilirubin builds up in blood.

What are the symptoms of Gilbert's syndrome?

Approximately 1 in 3 people with Gilbert's syndrome don’t have symptoms. They learn that they have the disease after getting blood tests to check for a different problem.

Among those with symptoms, the most common sign is jaundice, brought on by elevated levels of bilirubin in blood. Jaundice can turn your skin and whites of the eyes yellow, but it isn’t harmful.

Occasionally, people who have jaundice or Gilbert's syndrome also experience:

* Dark-colored urine or clay-colored stool.
* Difficulty concentrating.
* Dizziness.
* Gastrointestinal problems, such as abdominal pain, diarrhea and nausea.
* Fatigue.
* Flu-like symptoms, including fever and chills.
* Loss of appetite.

What worsens symptoms of Gilbert's syndrome?

These things can raise bilirubin levels in people with Gilbert's syndrome, leading to jaundice:

* Dehydration.
* Fasting or skipping meals.
* Illness or infections.
* Menstruation.
* Overexertion (too much physical activity).
* Stress.

Diagnosis and Tests:

How is Gilbert's syndrome diagnosed?

As a genetic condition, Gilbert's syndrome is present at birth. It often remains undiagnosed until blood tests detect high bilirubin levels. Diagnosis most commonly occurs when people are in their teens or early adulthood and getting blood tests for something else.

In addition to blood tests, you may get:

* Liver function tests to assess how well your liver is working and measure bilirubin levels.
* Genetic tests to check for the gene mutation that causes Gilbert's syndrome.

Management and Treatment:

What are the complications of Gilbert's syndrome?

Gilbert's syndrome is a mild condition. It doesn’t cause long-term complications or serious health problems.

How is Gilbert's syndrome managed or treated?

Jaundice can cause a yellowish appearance that may be unsettling. However, jaundice and Gilbert's syndrome don’t require treatment.

Additional Information:

Overview

Gilbert syndrome is a harmless liver condition in which the liver doesn't properly process bilirubin. Bilirubin is a substance produced by the breakdown of red blood cells.

Gilbert syndrome is a genetic condition passed down from your parents. You might not know you have Gilbert syndrome until it's discovered by accident, such as when a blood test shows raised bilirubin levels.

Gilbert syndrome needs no treatment.

The liver

The liver is your largest internal organ. About the size of a football, it's located mainly in the upper right portion of your abdomen — beneath the diaphragm and above your stomach. A small portion extends into the upper left quadrant.

Symptoms

The most common sign of Gilbert syndrome is an occasional yellowish tinge of the skin and the whites of the eyes, called jaundice. Jaundice is a result of slightly higher levels of bilirubin in the blood.

In people with Gilbert syndrome, bilirubin levels may increase due to:

* Illness, such as a cold or the flu.
* Fasting or eating a very low-calorie diet.
* Dehydration.
* Menstruation.
* Strenuous exercise.
* Stress.

When to see a doctor

Make an appointment with a healthcare professional if you have jaundice, which has many possible causes.

Causes

Gilbert syndrome is caused by a modified gene someone inherits from their parents. This gene usually controls an enzyme that helps break down bilirubin in the liver. When someone has this ineffective gene, their blood contains too much bilirubin. This is because the body isn't producing enough of the enzyme.

How the body processes bilirubin

Bilirubin is a yellowish pigment made when the body breaks down old red blood cells. Bilirubin travels through the bloodstream to the liver, where the enzyme breaks down the pigment and removes it from the bloodstream.

The bilirubin passes from the liver into the intestines with bile. It's then excreted in stool. A small amount of bilirubin remains in the blood.

How the modified gene is passed through families

The modified gene that causes Gilbert syndrome is common. Many people carry one copy of this gene. In most cases, two modified copies are needed to cause Gilbert syndrome.

Risk factors

Although it's present from birth, Gilbert syndrome usually isn't noticed until puberty or later. This is because bilirubin production increases during puberty. Risk factors for Gilbert syndrome include:

* Both parents carry the modified gene that causes the disorder.
* Being male.

Complications

The low level of the bilirubin-processing enzyme that causes Gilbert syndrome also may increase the side effects of certain medicines, since this enzyme plays a role in helping clear these medicines from the body.

These medicines include:

* Irinotecan (Camptosar), a cancer chemotherapy drug.
* Some protease inhibitors used to treat HIV.

If you have Gilbert syndrome, talk to a healthcare professional before taking new medicines. Also, having any other condition that affects the destruction of red blood cells may increase the risk of developing gallstones.

Jai Ganesh · This is Cool

Smartphone

Gist

A cellphone is a mobile device for calls and texts, while a smartphone is a type of cellphone with advanced computing, internet, and app capabilities, essentially blending a phone with a handheld computer. All smartphones are cellphones, but basic cellphones (also called feature phones) lack the sophisticated operating systems, app stores, and features like GPS, email, and advanced cameras found on smartphones.

Smartphones offer a range of different benefits such as increased portability, improved user experience and accessibility compared to traditional computers. With smartphones users have instantaneous access to important documents, emails and applications which allows them to work more efficiently on the go.

Summary

A smartphone is a mobile device that combines the functionality of a traditional mobile phone with advanced computing capabilities. It typically has a touchscreen interface, allowing users to access a wide range of applications and services, such as web browsing, email, and social media, as well as multimedia playback and streaming. Smartphones have built-in cameras, GPS navigation, and support for various communication methods, including voice calls, text messaging, and internet-based messaging apps. Smartphones are distinguished from older-design feature phones by their more advanced hardware capabilities and extensive mobile operating systems, access to the internet, business applications, mobile payments, and multimedia functionality, including music, video, gaming, radio, and television.

Smartphones typically feature metal–oxide–semiconductor (MOS) integrated circuit (IC) chips, various sensors, and support for multiple wireless communication protocols. Examples of smartphone sensors include accelerometers, barometers, gyroscopes, and magnetometers; they can be used by both pre-installed and third-party software to enhance functionality. Wireless communication standards supported by smartphones include LTE, 5G NR, Wi-Fi, Bluetooth, and satellite navigation. By the mid-2020s, manufacturers began integrating satellite messaging and emergency services, expanding their utility in remote areas without reliable cellular coverage. Smartphones have largely replaced personal digital assistant (PDA) devices, handheld/palm-sized PCs, portable media players (PMP), point-and-shoot cameras, camcorders, and, to a lesser extent, handheld video game consoles, e-reader devices, pocket calculators, and GPS tracking units.

Following the rising popularity of the iPhone in the late 2000s, the majority of smartphones have featured thin, slate-like form factors with large, capacitive touch screens with support for multi-touch gestures rather than physical keyboards. Most modern smartphones have the ability for users to download or purchase additional applications from a centralized app store. They often have support for cloud storage and cloud synchronization, and virtual assistants. Since the early 2010s, improved hardware and faster wireless communication have bolstered the growth of the smartphone industry. As of 2014, over a billion smartphones are sold globally every year. In 2019 alone, 1.54 billion smartphone units were shipped worldwide. As of 2020, 75.05 percent of the world population were smartphone users.

Details

Isn’t it great when science fiction becomes science fact? If you’re a little older, you probably wanted a communication device just like the one Captain Kirk used in the TV series “Star Trek” when you were growing up. Kirk and the crew of the USS Enterprise could talk over vast distances with these personal communication devices. Without the “communicator, the order to “beam us up, Mr. Scott” would have fallen on deaf ears, and we all know what would have happened to Kirk if he didn’t have any bars on his device.

Now that we’re well into the 21st century, our “communicators” make the ones on “Star Trek” seem like antiques. Not only can we talk to one another on our smartphones, but we can text, play music or a game, get directions, take pictures, check e-mail, find a great restaurant, surf the Internet, watch a movie. You get the idea. Smartphones are cell phones on steroids. Why is that?

Unlike traditional cell phones, smartphones, with their big old memories, allow individual users like you and me to install, configure and run applications, or apps, of our choosing. A smartphone offers the ability to configure the device to your particular way of doing things. The software in the old-style flip phones offers only limited choices for reconfiguration, forcing you to adapt to the way they are set up. On a standard phone, whether or not you like the built-in calendar application, you’re stuck with it except for a few minor tweaks. But if that phone were a smartphone, you could install any compatible calendar application you liked.

Here's a list of some of the additional capabilities smartphones have, from intuitive to perhaps less so:

* Manage your personal info including notes, calendar and to-do lists
* Communicate with laptop or desktop computers
* Sync data with applications like Microsoft Outlook and Apple's iCal calendar programs
* Host applications such as word processing programs or video games
* Scan a receipt
* Cash a check
* Replace your wallet. A smartphone can store credit card information and discount or membership card info
* Pay bills by downloading apps such as PayPal and CardStar
* Allow you to create a WiFi network that multiple devices can use simultaneously. That means you can access the Internet from your iPad or laptop without a router or another peripheral device.

Work:

The Layers of a Smartphone

Everyone has a smartphone, or so it seems. In fact, there were an estimated 1.4 billion smartphones in the world as of December 2013. People are constantly talking on them, taking pictures, surfing the Internet and doing dozens of other things, including shopping for cars. Captain Kirk would be jealous.

At their core, smartphones, and all cell phones for that matter, are mini radios, sending and receiving radio signals. Cell phone networks are divided into specific areas called cells. Each cell has an antenna that receives cell phone signals. The antenna transmits signals just like a radio station, and your phone picks up those signals just as a radio does.

Smartphones use cell phone network technology to send and receive data (think phone calls, Web browsing, file transfers). Developers classify this technology into generations. Do you remember the first generation? It included analog cell phone technology. However, as cell phone technology progressed, the protocols became more advanced. In 2014, cell phones are in the world of the fourth generation, or 4G. Although most carriers are expanding their 4G technology, some companies, such as Samsung, are developing 5G technology, which if recent tests are any indication, will allow you to download an entire movie in less than a second. You can read more about network technologies and protocols in the article How Cell Phones Work.

Smartphone Hardware and Software

Smartphone Hardware and Software
As long as we're talking details, let's have a quick look at smartphone hardware.

Some smartphones run on processors. Along with processors, smartphones also have computer chips that provide functionality. Phones with cameras have high-resolution image sensors, just like digital cameras. Other chips support complex functions such as browsing the Internet, sharing multimedia files or playing music without placing too great a demand on the phone’s battery. Some manufacturers develop chips that integrate multiple functions to help reduce the overall cost (fewer chips produced per phone help offset production costs).

You can visualize software for smartphones as a software stack. The stack consists of the following layers:

kernel -- management systems for processes and drivers for hardware
middleware -- software libraries that enable smartphone applications (such as security, Web browsing and messaging)
application execution environment (AEE) -- application programming interfaces, which allow developers to create their own programs
user interface framework -- the graphics and layouts seen on the screen
application suite -- the basic applications users access regularly such as menu screens, calendars and message inboxes

Smartphone Operating Systems

The most important software in any smartphone is its operating system (OS). An operating system manages the hardware and software resources of smartphones. Some platforms cover the entire range of the software stack. Others may only include the lower levels (typically the kernel and middleware layers) and rely on additional software platforms to provide a user interface framework. We've added some snapshots of specific smartphone operating systems.

Designed primarily for touch-screen mobile devices, Android, or Droid, technology is the operating system that most mobile telephones used as of Comscore's February 2014 numbers. Developed by Google, most people consider the Droid technology revolutionary because its open source technology allows people to write program codes and applications for the operating system, which means Android is evolving constantly. Smartphone users can decide whether to download the applications. Moreover, Android operating systems can run multiple applications, allowing users to be multitasking mavens. And get this: Any hardware manufacturer is free to produce its own Android phone by using the operating system. In fact, many smartphone companies do just that. Android app’s store has hundreds of thousands of apps.

Apple is always innovating, and iOS allows iPhone screens to be used simply and logically. Touted by Apple as the “world’s most advance mobile operating system,” iOS supports more access from sports scores to restaurant recommendations. As of publication, its latest version iOS7 allows for automatic updates and a control center that gives users access to their most used features. It also makes surfing the net easier with an overhaul to the Safari browser.

Reviewers say that Windows Phone 8 (WP8) is as simple to use as iOS and as easy to customize as Android. Its crowning achievement is LiveTiles, which are programmed squares that users can rearrange on their screen to easily access the information they want. WP8 works well with other Microsoft products, including Office and Exchange. For those who do a lot of calling, connecting to Facebook and texting, WP8 may meet their needs.

At first glance, experts say, Ubuntu 13.10 Touch might seem like an ordinary operating system, but it’s not. Experts say Ubuntu Touch one of the easiest systems to use, allowing seamless navigation with multiple scopes. There are no hardware buttons on the bottom, for example. Instead, Ubuntu works from the edges. Developed by Canonical, the Ubuntu Touch allows users to unlock the phone from the right edge. You can swipe down from the top edge to access the phone’s indicators, including date, time, messages (from variety of sources, ie: Skype and Facebook) and wireless networks. The phone also makes it easy for people to organize and share photos. Every shot is automatically uploaded to a personal cloud account, which makes it available on all devices, including iOS, Android and Windows.

Flexible Interfaces

The core services on smartphones all tie in to the idea of a multipurpose device that can effectively multitask. A user can watch a video, field a phone call, then return to the video after the call, all without closing each application. Or he or she can flip through the digital calendar and to-do list applications without interrupting the voice call. All of the data stored on the phone can be synchronized with outside applications or manipulated by third-party phone applications in numerous ways. Here are a few systems that smartphones support.

Bluetooth

This short-range radio service allows phones to wirelessly link up with each other and with other nearby devices that support it. Examples include printers, scanners, input devices, computers and headsets.

Some varieties of Bluetooth only allow communication with one device at a time, but others allow simultaneous connection with multiple devices. To learn more, check out How Bluetooth Works.

Data Synchronization

A phone that keeps track of your personal information, like appointments, to-do lists, addresses, and phone numbers, needs to be able to communicate with all of the other devices you use to keep track of those things. There are hundreds of possible platforms and applications you might use for this in the course of a day. If you want to keep all of this data synchronized with what's on your phone, then you generally have to look for a cell phone that speaks the languages of all of the devices and applications you use. Or you can go out and buy new applications that speak the language of your cell phone.

The Open Mobile Alliance (OMA) is a collaborative organization with the following mission:

* Be the center of mobile service enabler specification work, helping the creation of interoperable services across countries, operators and mobile terminals that will meet the needs of the user.

The OMA formed a Data Synchronization Working Group, which continued the work begun by the SyncML Initiative. SyncML was an open-standards project designed to eliminate the trouble of worrying about whether your personal information manager tools sync up with your phone and vice versa. The project is designed so that any kind of data can be synchronized with any application on any piece of hardware, through any network, provided that they are all programmed to OMA standards. This includes synchronization over the Web, Bluetooth, mail protocols and TCP/IP networks.

SyncML allows data to be synchronized from a phone to Windows, Mac and Linux applications using Bluetooth, infrared, HTTP or a USB cable. Visit the OMA Web site for more information.

Java

A smartphone that's compatible with the Java programming language allows the user to load and run Java applications and MIDlets. MIDlets are applications that use a subset of Java and are specifically programmed to run on wireless devices. Java MIDlets include add-ons, games, applications and utilities.

Since there are millions of Java developers worldwide, and the Java development tools are freely accessible, smartphone users can install thousands of third-party applications on their phones. Because of the way the OS architecture of most phones is built, these applications can access and use all of the data on the user's phone.

The Future of Smartphones

With data transmission rates reaching blistering speeds and the incorporation of WiFi technology, the sky is the limit on what smartphones can do. Possibly the most exciting thing about smartphone technology is that the field is still wide open. It's an idea that probably hasn't found its perfect, real-world implementation yet. Every crop of phones brings new designs and new interface ideas. No one developer or manufacturer has come up with the perfect shape, size or input method yet. The next "killer app" smartphone could look like a flip phone, a tablet PC, a candy bar or something no one has conceived of yet.

Perhaps the most challenging consideration for the future is security. Smartphones may be vulnerable to security breaches such as an Evil Twin attack. In one of these attacks, a hacker sets a server’s service identifier to that of a legitimate hotspot or network while simultaneously blocking traffic to the real server. When a user connects with the hacker’s server, information can be intercepted and security is compromised.

On the other side, some critics argue that anti-virus software manufacturers greatly exaggerate the risks, harms and scope of phone viruses in order to help sell their software. Read more in the article How Cell Phone Viruses Work.

The incredible diversity in smartphone hardware, software and network protocols inhibit practical, broad security measures. Most security considerations either focus on particular operating systems or have more to do with user behavior than network security.

Additional Information

A smartphone is a mobile telephone with a display screen (typically a liquid crystal display, or LCD), built-in personal information management programs (such as an electronic calendar and address book)), and an operating system (OS) that allows other computer software to be installed for Web browsing, email, music, video, and other applications. A smartphone may be thought of as a handheld computer integrated within a mobile telephone.

The first smartphone was designed by IBM and sold by BellSouth (formerly part of the AT&T Corporation) in 1993. It included a touchscreen interface for accessing its calendar, address book, calculator, and other functions. As the market matured and solid-state computer memory and integrated circuits became less expensive over the following decade, smartphones became more computer-like, and more advanced services, such as Internet access, became possible. Advanced services became ubiquitous with the introduction of the so-called third-generation (3G) mobile phone networks in 2001. Before 3G, most mobile phones could send and receive data at a rate sufficient for telephone calls and text messages. Using 3G, communication takes place at bit-rates high enough for sending and receiving photographs, video clips, music files, e-mails, and more. Most smartphone manufacturers license an operating system, such as Microsoft Corporation’s Windows Mobile OS, Symbian OS, Google’s Android OS, or Palm OS. Research in Motion’s BlackBerry and Apple Inc.’s iPhone have their own proprietary systems.

Smartphones contain either a keyboard integrated with the telephone number pad or a standard “QWERTY” keyboard for text messaging, e-mailing, and using Web browsers. “Virtual” keyboards can be integrated into a touch-screen design. Smartphones often have a built-in camera for recording and transmitting photographs and short videos. In addition, many smartphones can access Wi-Fi “hot spots” so that users can access VoIP (voice over Internet protocol) rather than pay cellular telephone transmission fees. The growing capabilities of handheld devices and transmission protocols have enabled a growing number of inventive and fanciful applications—for instance, “augmented reality,” in which a smartphone’s global positioning system (GPS) location chip can be used to overlay the phone’s camera view of a street scene with local tidbits of information, such as the identity of stores, points of interest, or real estate listings.

4G

4G (Fourth Generation) is a mobile network technology offering significantly faster data speeds than 3G, enabling HD streaming, faster browsing, and lower latency. It primarily uses 4G LTE (Long Term Evolution) to provide speeds, often up to 100 Mbps, and is designed for all-IP, packet-switched communication, including voice-over-LTE (VoLTE).

4G refers to the fourth generation of cellular network technology, introduced in the late 2000s and early 2010s. Compared to preceding third-generation (3G) technologies, 4G has been designed to support all-IP communications and broadband services, and eliminates circuit switching in voice telephony.[1] It also has considerably higher data bandwidth compared to 3G, enabling a variety of data-intensive applications such as high-definition media streaming and the expansion of Internet of Things (IoT) applications.

The earliest deployed technologies marketed as "4G" were Long Term Evolution (LTE), developed by the 3GPP group, and Mobile Worldwide Interoperability for Microwave Access (Mobile WiMAX), based on IEEE specifications. These provided significant enhancements over previous 3G and 2G.

Technical overview

In November 2008, the International Telecommunication Union-Radio communications sector (ITU-R) specified a set of requirements for 4G standards, named the International Mobile Telecommunications Advanced (IMT-Advanced) specification, setting peak speed requirements for 4G service at 100 megabits per second (Mbit/s)(=12.5 megabytes per second) for high mobility communication (such as from trains and cars) and 1 gigabit per second (Gbit/s) for low mobility communication (such as pedestrians and stationary users).[5]

Since the first-release versions of Mobile WiMAX and LTE support much less than 1 Gbit/s peak bit rate, they are not fully IMT-Advanced compliant, but are often branded 4G by service providers. According to operators, a generation of the network refers to the deployment of a new non-backward-compatible technology. On December 6, 2010, ITU-R recognized that these two technologies, as well as other beyond-3G technologies that do not fulfill the IMT-Advanced requirements, could nevertheless be considered "4G", provided they represent forerunners to IMT-Advanced compliant versions and "a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed". Both the original LTE and WiMAX standards had previously sometimes been referred to as 3.9G/3.95G. The ITU's new definition for 4G also included Evolved High Speed Packet Access (HSPA+).

Mobile WiMAX Release 2 (also known as WirelessMAN-Advanced or IEEE 802.16m) and LTE Advanced (LTE-A) are IMT-Advanced compliant backwards compatible versions of the above two systems, standardized during the spring 2011, and promising speeds in the order of 1 Gbit/s. In January 2012, the ITU backtracked on its previous definition for 4G, claiming that Mobile WiMAX 2 and LTE Advanced are "true 4G" while their predecessors are "transitional" 3G-4G.

As opposed to earlier generations, a 4G system does not support traditional circuit-switched telephony service, but instead relies on all-Internet Protocol (IP) based communication such as IP telephony. As seen below, the spread spectrum radio technology used in 3G systems is abandoned in all 4G candidate systems and replaced by OFDMA multi-carrier transmission and other frequency-domain equalization (FDE) schemes, making it possible to transfer very high bit rates despite extensive multi-path radio propagation (echoes). The peak bit rate is further improved by smart antenna arrays for multiple-input multiple-output (MIMO) communications.

5G

5G, fifth-generation telecommunications technology. Introduced in 2019 and now globally deployed, 5G delivers faster connectivity with higher bandwidth and “lower latency” (shorter delay times), improving the performance of phone calls, streaming, videoconferencing, gaming, and business applications as well as the responsiveness of connected systems and mobile apps. 5G can double the download speeds for smartphones and improve performance considerably more for devices tied to the Internet of Things (IoT).

5G technology improves the data processing of more-advanced digital operations such as those tied to machine learning (ML), artificial intelligence (AI), virtual reality (VR), and augmented reality (AR), improving performance and the user experience alike. It also better supports autonomous vehicles, drones, and other robotic systems.

How 5G works

5G signals rely on a different part of the radiofrequency spectrum than previous versions of cellular technology. As a result, mobile phones and other devices must be built with a specific 5G microchip.

Three primary types of 5G technology exist: low-band networks that support a wide coverage area but increase speeds only by about 20 percent over 4G; high-band networks that deliver ultrafast connectivity but which are limited by distance and access to 5G base stations (which transmit the signals for the technology); and mid-band networks that balance both speed and breadth of coverage. 5G also supports “OpenRoaming” capabilities that allow a user to switch seamlessly and automatically from a cellular to a Wi-Fi connection while traveling, eliminating any interruption of service and the need for entering passwords to access the latter.

Telecom providers use a different type of antenna, known as MIMO (multiple-input multiple-output), to transmit 5G signals. This does not require the traditional large cell tower (base station) but can be deployed through a multiplicity of “small cells” (which are the micro boxes commonly seen on poles and lamp posts). Many observers see this as an aesthetic improvement to the city landscape. Proximity to these cells remains an issue globally, however, especially for rural and remote regions, underscoring the current limitations of 5G.

Security concerns accompany changing technologies. Since 5G networks rely on cloud-based data storage, they are susceptible to the same possible dangers as other types of cellar and noncellular networks, including data damage, cyberattacks, and theft. Additionally, companies must be mindful of data-point vulnerabilities during a transition to 5G from networks with different security capabilities.

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Jai Ganesh · Science HQ

Mandible

Gist

In jawed vertebrates, the mandible (from the Latin mandibula, 'for chewing'), lower jaw, or jawbone is a bone that makes up the lower – and typically more mobile – component of the mouth (the upper jaw being known as the maxilla).

Upper jaw (maxilla): Fixed bone that holds your upper teeth and shapes your face. Lower jaw (mandible): The only movable bone in your skull and the strongest facial bone.

The mandible is the largest, strongest, and only movable bone in the human skull, forming the lower jaw, holding the lower teeth, and enabling mastication and speech. It is a U-shaped bone consisting of a horizontal body and two vertical rami that articulate with the temporal bone. It fuses into one bone in early life.

Summary

In jawed vertebrates, the mandible (from the Latin mandibula, 'for chewing'), lower jaw, or jawbone is a bone that makes up the lower – and typically more mobile – component of the mouth (the upper jaw being known as the maxilla).

The jawbone is the skull's only movable, posable bone, sharing joints with the cranium's temporal bones. The mandible hosts the lower teeth (their depth delineated by the alveolar process). Many muscles attach to the bone, which also hosts nerves (some connecting to the teeth) and blood vessels. Amongst other functions, the jawbone is essential for chewing food.

Owing to the Neolithic advent of agriculture (c. 10,000 BCE), human jaws evolved to be smaller. Although it is the strongest bone of the facial skeleton, the mandible tends to deform in old age; it is also subject to fracturing. Surgery allows for the removal of jawbone fragments (or its entirety) as well as regenerative methods. Additionally, the bone is of great forensic significance.

Details:

Introduction

The mandible is the largest and strongest bone of the human skull. It is commonly known as the lower jaw and is located inferior to the maxilla. It is composed of a horseshoe-shaped body which lodges the teeth, and a pair of rami which projects upwards to form a temporomandibular joint.

Structure

The mandible is formed by a body and a pair of rami along with condyloid and coronoid processes.

Body

Body is the anterior portion of the mandible. Body has two surfaces: outer and inner and two borders: upper and lower border. The body ends and the rami begin on either side at the angle of the mandible, also known as the gonial angle.

1. Outer surface is also known as external surface and has following characteristics:

* Mandibular symphysis/ Symphysis menti at midline which joins left and right half of the bone, detected as a subtle ridge in the adult.

* The inferior portion of the ridge divides and encloses a midline depression called the mental protuberance, also known as chin. The edges of the mental protuberance are elevated, forming the mental tubercle.

* Laterally to the ridge and below the incisive teeth is a depression known as the incisive fossa.

* Below the second premolar is the mental foramen, in which the mental nerve and vessels exit.

* The oblique line courses posteriorly from the mental tubercle to the anterior border of the ramus.

2. Inner surface is also known as internal surface and has following features:

* The mylohyoid line is a prominent ridge that runs obliquely downwards and forwards from below the third molar tooth to the median area below the genial tubercles.

* Below the mylohyoid line, the surface is slightly hollowed out to form the sub-mandibular fossa, which lodges the submandibular gland.

* Above the mylohyoid line, there is the sublingual fossa in which the sublingual gland lies.

* The posterior surface of the symphysis menti is marked by four small elevations called the superior and inferior genial tubercles.

3. Upper border (Alveolar border)

It consist of sockets for the teeth.

4. Lower border (Inferior border)

It is also known as base. There is a fossa present at the side of midline known as digastric fossa.

Ramus

The ramus is lateral continuation of the body and is quadrilateral in shape. The coronoid process is the anterosuperior projection of the ramus which is triangular in shape. Whereas posterosuperior projection of ramus is known as condyloid process whose head is covered with fibrocartilage and form a temporomandibular joint. The constricted part below condyloid process is neck. Condyloid and coronoid process are separated by a mandibular notch. It has two surfaces: medial and lateral and four borders: superior, inferior, anterior and posterior.

Ossification

Mandible is the second bone to ossify after clavicle. Each half of the mandible ossifies from only one centre at the sixth week of intrauterine life in the mesenchymal sheath of Meckel's cartilage near the future mental foramen. The first pharyngeal arch, known as the mandibular arch, gives rise to the Meckel cartilage. A fibrous membrane covers the left and right Meckel cartilage at their ventral ends. These two halves eventually fuse via fibrocartilage at the mandibular symphysis. Thus, at birth, the mandible is still composed of two separate bones. Ossification and fusion of the mandibular symphysis occur during the first year of life, resulting in a single bone. The remnant of the mandibular symphysis is a subtle ridge at the midline of the mandible.

The mandible changes throughout the life. In infant and children, the angle of mandible is obtuse with 140 degrees or more making head in line with the body of the mandible. Whereas in adult the angle decreases to about 110-120 degree making ramus almost vertical.

Additional Information

Mandible, in anatomy, is the movable lower jaw, consisting of a single bone or of completely fused bones in humans and other mammals. In birds, the mandible constitutes either the upper or the lower segment of the bill, and in invertebrates it is any of the various mouthparts that holds or bites food materials, including either of the paired mouth appendages of an arthropod that form the biting jaws.

In humans, the mandible is the only mobile bone of the skull (other than the tiny bones of the middle ear). It is attached to muscles involved in chewing and other mouth movements and functions by moving in opposition to the maxilla (upper jaw); together, the two parts are used for biting, chewing, and handling food. The structure of the human mandible resembles a more or less horizontal arch, which holds the teeth and contains blood vessels and nerves. At the rear of the mandible, two more or less vertical portions (rami) form movable hinge joints, one on each side of the head, articulating with the glenoid cavity of the temporal bone of the skull to form the temporomandibular joints. The rami also provide attachment for muscles important in chewing. The centre front of the arch is thickened and buttressed to form the chin, a development unique to humans and some of their recent ancestors; the great apes and other animals lack chins. In the human fetus and infant, the maxilla and the mandible are each separated at the midline; the halves fuse a few months after birth.

Invertebrate jaw and mouthpart structures vary markedly. For example, in the primitive bloodsucking flies (e.g., the horse fly [Tabanus]), the mandibles and maxillae form serrated blades that cut through the skin and blood vessels of the host animal. In the mosquito (Culicidae), the mandibles and associated structures have become exceedingly slender stylets that form a fine bundle used for piercing skin and entering blood vessels. In the housefly (Musca domestica), the mandibles and maxillae have been lost; the tonguelike labium alone remains and serves for feeding on exposed surfaces. Among crustaceans, processes at the base of the antennae may help the mandibles push food into the mouth. The paired mandibles of a nauplius (the most widespread and typical crustacean larva to emerge from the egg) each have two branches, one with a chewing lobe and the other with a compressing lobe at the base; the mandibles may also be used for swimming. In the adult crustacean, each mandible loses one of the branches, sometimes retaining the other as a palp, and the base may develop into a powerful jaw. An alternative development is found in some of the blood-sucking parasites, in which the mandibles form needlelike stylets for piercing a host.

In humans, the most common conditions that affect the function of the mandible are temporomandibular joint disorders (TMDs), of which there are about 30 different types. TMDs may have an impact on the function of the jaw muscles and the temporomandibular joints and may irritate associated nerves. The cause of a TMD is often unclear; factors that may play a role include osteoarthritis and physical trauma. Symptoms vary but may include dizziness, earache, facial pain, headache, jaw tenderness, and reduced jaw mobility. Many TMDs resolve on their own; otherwise, treatment ranges from simple dietary changes (e.g., eating only soft foods) to physical therapy or medication to the use of intraoral appliances (devices fitted over the teeth) to complex surgical or dental procedures.

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