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#1 2017-08-23 21:45:48

ganesh
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Registered: 2005-06-28
Posts: 23,209

Miscellany

1) The General Sherman Tree, a giant sequoia in California's Sequoia and Kings Canyon National Park, is the largest tree in the world, and is also among the oldest. It is undoubtedly one of the major attractions of the park for visitors, an awe-inspiring sight that exemplifies the remarkable ecology that warrants the national park's designation as a UN Biosphere Reserve.

Location and Access

The General Sherman Tree is located in Sequoia and Kings Canyon National Park in California. Specifically, the tree is located at the north end of Giant Forest, one of the park's five sub-regions. The Giant Forest section offers 40 miles of trails, two of which -- the General Sherman Tree Trail and the Big Trees Trail -- lead directly to the General Sherman Tree. Trail guides are available at visitor centers, and park rangers can give you more information. Another way to reach the tree is by taking the free Sequoia Shuttle, which operates daily from the end of May to the end of September. Route 1 on the green bus stops at the General Sherman Tree, as well as the Giant Forest Museum and the Lodgepole Visitor Center and Campground.

Size

The General Sherman Tree is considered the largest tree in the world by volume. Its volume, most recently calculated in 1975, is 52,500 cubic feet, a figure determined by measuring only the trunk of the tree according to accepted standards. This means that when large branches fall, it does not affect the official size of the tree. According to the National Park Service, the General Sherman Tree is 274.9 feet tall with a circumference at the ground of 102.6 feet. The diameter of its largest branch measures 6.8 feet, the first large branch is 130 feet above the base of the tree, and the average crown spread is 106.5 feet across. It is not the tallest tree in the world -- this title is claimed by a coastal redwood called Hyperion in Redwood National Park, also in California.

History

The General Sherman Tree is estimated to be between 2,300 and 2,700 years old, with research conducted in 2002 concluding that it is closer to 2,000 years old. It received its moniker in 1879 in honor of the Civil War General William Tecumseh Sherman. A wagon road constructed in the early 1900s passed by the General Sherman Tree, revealing it to vehicular tourists for the first time. Improvements made to the road over the ensuing years improved access to the Giant Forest. In 2005, a 2.5-acre parking lot near the General Sherman Tree was demolished and restored to forest land in order to improve the natural setting.

Fun Facts

The trunk of the General Sherman Tree could theoretically be turned into almost 120 miles of standard sized lumber planks. A branch that fell from the tree in 1978 had a diameter greater than six feet and was at least 140 feet long -- larger than any tree in the United States east of the Sierra Nevada and Cascade mountain ranges. The General Sherman is not the only giant tree in Sequoia National Park; in fact, the five largest trees in the world are all located in the park, with three others found in the Giant Forest section.


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#2 2017-08-25 00:33:33

ganesh
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Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

2) Epsilon Eridani is the closest star known to have a planet: and maybe two of them. It is the only system that has both precise Doppler data and long-baseline astrometric positional observations, which combined yield the orbital tilt and the true planetary mass. Given its closeness and the knowledge of where it is relative to its star, the planet may become the first ever actually imaged.

The Planet

The circle shows the location of the class K (K2) dwarf star Epsilon Eridani (in the constellation Eridanus). At a distance of only 10.5 light years, the star is the closest to the Sun for which an extrasolar planet is known. With an average orbital radius 3.39 times that of the distance between the Sun and Earth (the Astronomical Unit, AU), 65% of the way from the Sun to Jupiter, the planet takes 6.85 years to make an orbit. Combination of stellar velocity and positional measures of the star show the planet to have a mass 1.55 times that of Jupiter with an uncertainty of only 15 percent. The orbital inclination of 30 degrees to the plane of the sky agrees well with the inclination of a dusty circumstellar disk. Unlike Jupiter, the planet is in a highly eccentric orbit that takes it from as far as 5.8 AU from the star (just farther than Jupiter is from the Sun) to as close as 1.1 AU. The planet will be farthest from Epsilon Eridani proper, 1.7 seconds of arc, late in the year 2010, when we have the best hope of imaging it directly even though it will be 20 million times fainter than the star. Slow changes in the apparent orbit suggest another "Jupiter" with a period greater than 50 years (which would place it at least 13 AU from the star).

The Star

Epsilon Eridani is a fourth magnitude (on the bright side, 3.73) class K (K2) ordinary, though relatively young, hydrogen-fusing dwarf. A mere 10.5 light years away, it is the 10th closest star system to the Earth. Its temperature of 5080 degrees Kelvin (88 percent that of the Sun) and low luminosity (34 percent solar) tell of a lower mass, just 83 percent that of the Sun. Though its rotation speed appears similar to that of the Sun, Epsilon Eridani is much younger (about 800 million years, as opposed to the Sun's 4.6 billion), and displays considerable solar- like activity. Unlike many stars so far found to have planets, Epsilon Eridani is not metal-rich, its metal content actually a bit less than that of the Sun (about 80 percent solar). The star achieved lasting fame as one of the first to be examined for radio signals produced by intelligent life, when Frank Drake turned an 85-foot radio telescope to it and to Tau Ceti in 1960. No signals were found. At least now the star does indeed appear to have a real planet, though as a Jupiter-like body, one incapable of supporting life.


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#3 2017-08-26 01:11:11

ganesh
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Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

3) The stethoscope is an acoustic medical device for auscultation, or listening to the internal sounds of an animal or human body. It typically has a small disc-shaped resonator that is placed against the chest, and two tubes connected to earpieces. It is often used to listen to lung and heart sounds. It is also used to listen to intestines and blood flow in arteries and veins. In combination with a sphygmomanometer, it is commonly used for measurements of blood pressure. Less commonly, "mechanic's stethoscopes", equipped with rod shaped chestpieces, are used to listen to internal sounds made by machines (for example, sounds and vibrations emitted by worn ball bearings), such as diagnosing a malfunctioning automobile engine by listening to the sounds of its internal parts. Stethoscopes can also be used to check scientific vacuum chambers for leaks, and for various other small-scale acoustic monitoring tasks. A stethoscope that intensifies auscultatory sounds is called phonendoscope.

History

The stethoscope was invented in France in 1816 by René Laennec at the Necker-Enfants Malades Hospital in Paris. It consisted of a wooden tube and was monaural. Laennec invented the stethoscope because he was uncomfortable placing his ear on women's chests to hear heart sounds. He observed that a rolled notebook, placed between the patient's chest and his ear, could amplify heart sounds without requiring physical contact. Laennec's device was similar to the common ear trumpet, a historical form of hearing aid; indeed, his invention was almost indistinguishable in structure and function from the trumpet, which was commonly called a "microphone". Laennec called his device the "stethoscope" (stetho- + -scope, "chest scope"), and he called its use "mediate auscultation", because it was auscultation with a tool intermediate between the patient's body and the physician's ear. (Today the word auscultation denotes all such listening, mediate or not.) The first flexible stethoscope of any sort may have been a binaural instrument with articulated joints not very clearly described in 1829. In 1840, Golding Bird described a stethoscope he had been using with a flexible tube. Bird was the first to publish a description of such a stethoscope but he noted in his paper the prior existence of an earlier design (which he thought was of little utility) which he described as the snake ear trumpet. Bird's stethoscope had a single earpiece.

In 1851, Irish physician Arthur Leared invented a binaural stethoscope and, in 1852, George Philip Cammann perfected the design of the stethoscope instrument (that used both ears) for commercial production, which has become the standard ever since. Cammann also wrote a major treatise on diagnosis by auscultation, which the refined binaural stethoscope made possible. By 1873, there were descriptions of a differential stethoscope that could connect to slightly different locations to create a slight stereo effect, though this did not become a standard tool in clinical practice.

The medical historian Jacalyn Duffin has argued that the invention of the stethoscope marked a major step in the redefinition of disease from being a bundle of symptoms, to the current sense of a disease as a problem with an anatomical system even if there are no noticeable symptoms. This re-conceptualization occurred in part, Duffin argues, because prior to stethoscopes, there were no non-lethal instruments for exploring internal anatomy.

Rappaport and Sprague designed a new stethoscope in the 1940s, which became the standard by which other stethoscopes are measured, consisting of two sides, one of which is used for the respiratory system, the other for the cardiovascular system. The Rappaport-Sprague was later made by Hewlett-Packard. HP's medical products division was spun off as part of Agilent Technologies, Inc., where it became Agilent Healthcare. Agilent Healthcare was purchased by Philips which became Philips Medical Systems, before the walnut-boxed, $300, original Rappaport-Sprague stethoscope was finally abandoned ca. 2004, along with Philips' brand (manufactured by Andromed, of Montreal, Canada) electronic stethoscope model. The Rappaport-Sprague model stethoscope was heavy and short (18-24 in (46-61 cm)) with an antiquated appearance recognizable by their two large independent latex rubber tubes connecting an exposed leaf-spring-joined pair of opposing F-shaped chrome-plated brass binaural ear tubes with a dual-head chest piece.

Several other minor refinements were made to stethoscopes until, in the early 1960s, David Littmann, a Harvard Medical School professor, created a new stethoscope that was lighter than previous models and had improved acoustics. In the late 1970s, 3M-Littmann introduced the tunable diaphragm: a very hard (G-10) glass-epoxy resin diaphragm member with an overmolded silicone flexible acoustic surround which permitted increased excursion of the diaphragm member in a Z-axis with respect to the plane of the sound collecting area. The left shift to a lower resonant frequency increases the volume of some low frequency sounds due to the longer waves propagated by the increased excursion of the hard diaphragm member suspended in the concentric accountic surround. Conversely, restricting excursion of the diaphragm by pressing the stethoscope diaphragm surface firmly against the anatomical area overlying the physiological sounds of interest, the acoustic surround could also be used to dampen excursion of the diaphragm in response to "z"-axis pressure against a concentric fret. This raises the frequency bias by shortening the wavelength to auscultate a higher range of physiological sounds.

In 1999, Richard Deslauriers patented the first external noise reducing stethoscope, the DRG Puretone. It featured two parallel lumens containing two steel coils which dissipated infiltrating noise as inaudible heat energy. The steel coil "insulation" added .30 lb to each stethoscope. In 2005, DRG's diagnostics division was acquired by TRIMLINE Medical Products.

Current practice

Stethoscopes are often considered as a symbol of healthcare professionals, as various healthcare providers are often seen or depicted with stethoscopes hanging around their necks. A 2012 research paper claimed that the stethoscope, when compared to other medical equipment, had the highest positive impact on the perceived trustworthiness of the practitioner seen with it.

The advent of practical, widespread portable ultrasonography (point-of-care ultrasonography) in the late 1990s to early 2000s led some physicians to ask how soon it would be before stethoscopes would become obsolete. Others answered that they thought the relationship of the various tools (stethoscopes and digital devices) would change but that it would be a long time before stethoscopes were obsolete. A decade later, in 2016, the same two sides of the coin were still recognized. One cardiologist said, "the stethoscope is dead", but a pediatrician said, "We are not at the place, and probably won't be for a very long time", where stethoscopes were obsolete. One consideration is that it depends on the segment of health care (emergency medical services, nursing, medicine) and the specialty. "Stethoscopes retain their value for listening to lungs and bowels for clues of disease, experts agree." But for the cardiovascular system, "auscultation is superfluous", one cardiologist said. Thus, it could be that cardiology in the secondary and tertiary care settings may abandon the stethoscope many years before primary care, pediatrics, and physical therapy do.

Types:

Acoustic

Acoustic stethoscopes are familiar to most people, and operate on the transmission of sound from the chest piece, via air-filled hollow tubes, to the listener's ears. The chestpiece usually consists of two sides that can be placed against the patient for sensing sound; a diaphragm (plastic disc) or bell (hollow cup). If the diaphragm is placed on the patient, body sounds vibrate the diaphragm, creating acoustic pressure waves which travel up the tubing to the listener's ears. If the bell is placed on the patient, the vibrations of the skin directly produce acoustic pressure waves traveling up to the listener's ears. The bell transmits low frequency sounds, while the diaphragm transmits higher frequency sounds. This two-sided stethoscope was invented by Rappaport and Sprague in the early part of the 20th century.

One problem with acoustic stethoscopes was that the sound level was extremely low. This problem was surmounted in 1999 with the invention of the stratified continuous (inner) lumen, and the kinetic acoustic mechanism in 2002.

Electronic

An electronic stethoscope (or stethophone) overcomes the low sound levels by electronically amplifying body sounds. However, amplification of stethoscope contact artifacts, and component cutoffs (frequency response thresholds of electronic stethoscope microphones, pre-amps, amps, and speakers) limit electronically amplified stethoscopes' overall utility by amplifying mid-range sounds, while simultaneously attenuating high- and low- frequency range sounds. Currently, a number of companies offer electronic stethoscopes. Electronic stethoscopes require conversion of acoustic sound waves to electrical signals which can then be amplified and processed for optimal listening. Unlike acoustic stethoscopes, which are all based on the same physics, transducers in electronic stethoscopes vary widely. The simplest and least effective method of sound detection is achieved by placing a microphone in the chestpiece. This method suffers from ambient noise interference and has fallen out of favor. Another method, used in Welch-Allyn's Meditron stethoscope, comprises placement of a piezoelectric crystal at the head of a metal shaft, the bottom of the shaft making contact with a diaphragm. 3M also uses a piezo-electric crystal placed within foam behind a thick rubber-like diaphragm. The Thinklabs' Rhythm 32 uses an Electromagnetic Diaphragm with a conductive inner surface to form a capacitive sensor. This diaphragm responds to sound waves, with changes in an electric field replacing changes in air pressure. The Eko Core enables wireless transmission of heart sounds to a smartphone or tablet.

Because the sounds are transmitted electronically, an electronic stethoscope can be a wireless device, can be a recording device, and can provide noise reduction, signal enhancement, and both visual and audio output. Around 2001, Stethographics introduced PC-based software which enabled a phonocardiograph, graphic representation of cardiologic and pulmonologic sounds to be generated, and interpreted according to related algorithms. All of these features are helpful for purposes of telemedicine (remote diagnosis) and teaching.

Electronic stethoscopes are also used with Computer-aided Auscultation programs to analyze the recorded heart sounds pathological or innocent heart murmurs.

Recording

Some electronic stethoscopes feature direct audio output that can be used with an external recording device, such as a laptop or MP3 recorder. The same connection can be used to listen to the previously recorded auscultation through the stethoscope headphones, allowing for more detailed study for general research as well as evaluation and consultation regarding a particular patient's condition and telemedicine, or remote diagnosis.

There are some smartphone apps that can use the phone as a stethoscope. At least one uses the phone's own microphone to amplify sound, produce a visualization, and e-mail the results. These apps may be used for training purposes or as novelties, but have not yet gained acceptance for professional medical use.

The first stethoscope that could work with a smartphone application was introduced in 2015.

Fetal

A fetal stethoscope or fetoscope is an acoustic stethoscope shaped like a listening trumpet. It is placed against the abdomen of a pregnant woman to listen to the heart sounds of the fetus. The fetal stethoscope is also known as a Pinard horn after French obstetrician Adolphe Pinard (1844 - 1934).

Doppler

A Doppler stethoscope is an electronic device that measures the Doppler effect of ultrasound waves reflected from organs within the body. Motion is detected by the change in frequency, due to the Doppler effect, of the reflected waves. Hence the Doppler stethoscope is particularly suited to deal with moving objects such as a beating heart. It was recently demonstrated that continuous Doppler enables the auscultation of valvular movements and blood flow sounds that are undetected during cardiac examination with a stethoscope in adults. The Doppler auscultation presented a sensitivity of 84% for the detection of aortic regurgitations while classic stethoscope auscultation presented a sensitivity of 58%. Moreover, Doppler auscultation was superior in the detection of impaired ventricular relaxation. Since the physics of Doppler auscultation and classic auscultation are different, it has been suggested that both methods could complement each other. A military noise-immune Doppler based stethoscope has recently been developed for auscultation of patients in loud sound environments (up to 110 dB).

3D-printed

A 3D-printed stethoscope is an open-source medical device meant for auscultation and manufactured via means of 3D printing. The 3D stethoscope was developed by Dr. Tarek Loubani and a team of medical and technology specialists. The 3D-stethoscope was developed as part of the Glia project, and its design is open source from the outset. The stethoscope gained widespread media coverage in Summer 2015.

The need for a 3D-stethoscope was borne out of a lack of stethoscopes and other vital medical equipment because of the blockade of the Gaza Strip, where Loubani, a Palestinian-Canadian, worked as an emergency physician during the 2012 conflict in Gaza. The 1960s-era Littmann Cardiology 3 stethoscope became the basis for the 3D-printed stethoscope developed by Loubani.

Earpieces

Stethoscopes usually have rubber earpieces, which aid comfort and create a seal with the ear, improving the acoustic function of the device. Stethoscopes can be modified by replacing the standard earpieces with moulded versions, which improve comfort and transmission of sound. Moulded earpieces can be cast by an audiologist or made by the stethoscope user from a kit.


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#4 2017-08-28 00:30:06

ganesh
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Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

4) The search for extra-terrestrial intelligence

With the cancellation of funding for an alien-hunting telescope in California, we look at the science behind the search for extra-terrestrial intelligence.

Where is everybody?
This was the question reportedly asked by nuclear physicist Enrico Fermi during a lunch at Los Alamos laboratory in New Mexico back in 1950.

It’s now known as the Fermi Paradox. It’s intended to highlight the apparent contradiction between high estimates of the probability that there are alien civilizations in our galaxy, and the lack of any evidence that they really do exist.

There are a number of attempted explanations of why this should be the case, such as alien civilizations being too far away, eventually being destroyed by themselves or by natural events - or because they aren’t there to find.

A decade after Fermi’s question, astrophysicist Frank Drake, the pioneer of the search for extraterrestrial intelligence, created what is now referred to as the Drake Equation to try to estimate the number of alien civilizations in our galaxy.

The equation is based on the star formation rate, the fraction of stars that have planets and the probabilities of, for example, the planets developing life and that life evolving intelligence.The problem is that we don’t accurately know the values of most of the variables, and Drake himself has said that his equation is just a way of “organising our ignorance” on the matter.

Most approaches aimed at detecting aliens involve listening out for signals and hoping we find something.

Listening out
Efforts to detect signs of extraterrestrial intelligence usually use radio telescopes, typically utilising a portion of their time that is not devoted to traditional radio astronomy.

Assuming that alien signals are much like our own, the data analysts are on the lookout for repeating signals with a narrow bandwidth.

But because there is little time dedicated to SETI activities, and resources are scarce, there have only been studies at a handful of frequencies from a few thousand star systems - out of more than 100 bn stars in total.

Arguably the best candidate for the detection of an artificial transmission so far is the “Wow!” signal, picked up in 1977 by the Big Ear radio telescope at Ohio State University.

It lasted for the entirety of the maximum 72 seconds for which it could be observed, suggesting a constant signal, and was at a frequency similar to that of hydrogen resonance, which has been suggested as one at which strong interstellar signals might be transmitted.

Repeated attempts to relocate the signal have not found anything, however.

Because using radio telescopes can only possibly detect civilizations that have reached a certain level of technology, some have suggested finding planets around other stars and monitoring their atmospheres.

This could first determine whether they’re capable of supporting life like that which is found on Earth, and then detect any changes in composition that would result from an industrial revolution.

Announcing our presence
Signals from Earth have been leaking into space, unwittingly announcing our presence to any extraterrestrial civilizations, since the first FM radio and TV transmissions.

Unlike some other frequencies, which bounce off the atmosphere, FM signals can penetrate it and be carried through space.

But any aliens wanting to catch 24-hour rolling news coverage would have to be nearby.

Until recently, TV transmissions have been omnidirectional - they spread out roughly equally in every direction through space. So their power decreases with the square of the distance that the signal has travelled through space, meaning that broadcasts would be extremely difficult to pick up at a range of more than a few tens of lightyears.

It will be even harder in the future because of both satellite television and the digital switchover.

Whereas the old type of broadcasts sent radio waves in every direction, the requirements of satellite TV mean sending them in tighter beams up to satellites and then back down to Earth again, so less of the signal leaks into space.

The UK is also due to switch over to digital rather than analogue broadcasting, and digital signals only need about a quarter of the power, making any transmission even weaker still by the time it reaches neighbouring stars.

But even if accidentally leaked messages are weak, we can still try to make contact deliberately by beaming messages towards a particular location in space.

This has been attempted several times, the best known of which was transmitted by the Arecibo radio observatory in 1974. The message was a sequence of binary digits, which, when decoded shows pictorial and mathematical representations of a human being, our solar system and DNA.

It was aimed at the M13 globular cluster of around 30 000 stars 21 000 light years away, which will no longer be there by the time the message arrives – it was intended more as a demonstration of technology and to be thought-provoking.

Although the power of deliberately transmitted beams doesn’t drop as rapidly as with accidental broadcasts, they are still only likely to be strong enough to be detected within perhaps a few hundred to a few thousand lightyears. The effective range of a transmission depends on several factors, including the frequency, bandwidth and transmission power, as this range-calculator shows.

Even for messages at high power, any extraterrestrials waiting to hear from us could need a radio dish several kilometres across. They may not have the budget for it.


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#5 2017-08-29 22:38:09

ganesh
Administrator
Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

5) The Egyptian Pyramids

Built during a time when Egypt was one of the richest and most powerful civilizations in the world, the pyramids - especially the Great Pyramids of Giza - are some of the most magnificent man-made structures in history. Their massive scale reflects the unique role that the pharaoh, or king, played in ancient Egyptian society. Though pyramids were built from the beginning of the Old Kingdom to the close of the Ptolemaic period in the fourth century A.D., the peak of pyramid building began with the late third dynasty and continued until roughly the sixth (c. 2325 B.C.). More than 4,000 years later, the Egyptian pyramids still retain much of their majesty, providing a glimpse into the country’s rich and glorious past.

The Pharaoh In Egyptian Society

During the third and fourth dynasties of the Old Kingdom, Egypt enjoyed tremendous economic prosperity and stability. Kings held a unique position in Egyptian society. Somewhere in between human and divine, they were believed to have been chosen by the gods to serve as mediators between them and the people on earth. Because of this, it was in everyone’s interest to keep the king’s majesty intact even after his death, when he was believed to become Osiris, god of the dead. The new pharaoh, in turn, became Horus, the falcon-god who served as protector of the sun-god, Ra.

Ancient Egyptians believed that when the king died, part of his spirit (known as “ka”) remained with his body. To properly care for his spirit, the corpse was mummified, and everything the king would need in the afterlife was buried with him, including gold vessels, food, furniture and other offerings. The pyramids became the focus of a cult of the dead king that was supposed to continue well after his death. Their riches would provide not only for him, but also for the relatives, officials and priests who were buried near him.

The Early Pyramids

Ancient Egyptians believed that when the king died, part of his spirit (known as “ka”) remained with his body. To properly care for his spirit, the corpse was mummified, and everything the king would need in the afterlife was buried with him, including gold vessels, food, furniture and other offerings. The pyramids became the focus of a cult of the dead king that was supposed to continue well after his death. Their riches would provide not only for him, but also for the relatives, officials and priests who were buried near him.

After Djoser, the stepped pyramid became the norm for royal burials, although none of those planned by his dynastic successors were completed (probably due to their relatively short reigns). The earliest tomb constructed as a “true” (smooth-sided, not stepped) pyramid was the Red Pyramid at Dahshur, one of three burial structures built for the first king of the fourth dynasty, Sneferu (2613-2589 B.C.) It was named for the color of the limestone blocks used to construct the pyramid’s core.

The Great Pyramids Of Giza

No pyramids are more celebrated than the Great Pyramids of Giza, located on a plateau on the west bank of the Nile River, on the outskirts of modern-day Cairo. The oldest and largest of the three pyramids at Giza, known as the Great Pyramid, is the only surviving structure out of the famed seven wonders of the ancient world. It was built for Khufu (Cheops, in Greek), Sneferu’s successor and the second of the eight kings of the fourth dynasty. Though Khufu reigned for 23 years (2589-2566 B.C.), relatively little is known of his reign beyond the grandeur of his pyramid. The sides of the pyramid’s base average 755.75 feet (230 meters), and its original height was 481.4 feet (147 meters), making it the largest pyramid in the world. Three small pyramids built for Khufu’s queens are lined up next to the Great Pyramid, and a tomb was found nearby containing the empty sarcophagus of his mother, Queen Hetepheres. Like other pyramids, Khufu’s is surrounded by rows of mastabas, where relatives or officials of the king were buried to accompany and support him in the afterlife.

The middle pyramid at Giza was built for Khufu’s son Khafre (2558-2532 B.C). A unique feature built inside Khafre’s pyramid complex was the Great Sphinx, a guardian statue carved in limestone with the head of a man and the body of a lion. It was the largest statue in the ancient world, measuring 240 feet long and 66 feet high. In the 18th dynasty (c. 1500 B.C.) the Great Sphinx would come to be worshiped itself, as the image of a local form of the god Horus. The southernmost pyramid at Giza was built for Khafre’s son Menkaure (2532-2503 B.C.). It is the shortest of the three pyramids (218 feet) and is a precursor of the smaller pyramids that would be constructed during the fifth and sixth dynasties.

Approximately 2.3 million blocks of stone (averaging about 2.5 tons each) had to be cut, transported and assembled to build Khufu’s Great Pyramid. The ancient Greek historian Herodotus wrote that it took 20 years to build and required the labor of 100,000 men, but later archaeological evidence suggests that the workforce might actually have been around 20,000. Though some popular versions of history held that the pyramids were built by slaves or foreigners forced into labor, skeletons excavated from the area show that the workers were probably native Egyptian agricultural laborers who worked on the pyramids during the time of year when the Nile River flooded much of the land nearby.

The End Of The Pyramid Era

Pyramids continued to be built throughout the fifth and sixth dynasties, but the general quality and scale of their construction declined over this period, along with the power and wealth of the kings themselves. In the later Old Kingdom pyramids, beginning with that of King Unas (2375-2345 B.C), pyramid builders began to inscribe written accounts of events in the king’s reign on the walls of the burial chamber and the rest of the pyramid’s interior. Known as pyramid texts, these are the earliest significant religious compositions known from ancient Egypt.

The last of the great pyramid builders was Pepy II (2278-2184 B.C.), the second king of the sixth dynasty, who came to power as a young boy and ruled for 94 years. By the time of his rule, Old Kingdom prosperity was dwindling, and the pharaoh had lost some of his quasi-divine status as the power of non-royal administrative officials grew. Pepy II’s pyramid, built at Saqqara and completed some 30 years into his reign, was much shorter (172 feet) than others of the Old Kingdom. With Pepy’s death, the kingdom and strong central government virtually collapsed, and Egypt entered a turbulent phase known as the First Intermediate Period. Later kings, of the 12th dynasty, would return to pyramid building during the so-called Middle Kingdom phase, but it was never on the same scale as the Great Pyramids.

The Pyramids Today

Tomb robbers and other vandals in both ancient and modern times removed most of the bodies and funeral goods from Egypt’s pyramids and plundered their exteriors as well. Stripped of most of their smooth white limestone coverings, the Great Pyramids no longer reach their original heights; Khufu’s, for example, measures only 451 feet high. Nonetheless, millions of people continue to visit the pyramids each year, drawn by their towering grandeur and the enduring allure of Egypt’s rich and glorious past.

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It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#6 2017-08-31 00:43:17

ganesh
Administrator
Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

6) General Packer Radio Service

General Packet Radio Service (GPRS) is a standard technology that extends GSM (global system for mobile) voice networks with support for data features. GPRS based networks are often called 2.5G networks and are gradually being phased out in favor of newer 3G/4G installations.

History of GPRS

GPRS was one of the first technologies that enabled a cell network to connect with Internet Protocol (IP) networks, achieving widespread adoption in the early 2000s (sometimes being called "GSM-IP").

The ability to browse the Web from a phone at any time ("always on" data networking), while taken for granted in much of the world today, was still a novelty then. Even today, GPRS continues to be used in parts of the world where it has been too costly to upgrade cellular network infrastructure to newer alternatives.

Mobile Internet providers offered GPRS data services together with voice subscription packages before 3G and 4G technologies became popular. Customers originally paid for GPRS service according to how much network bandwidth they used in sending and receiving data until providers changed to offer flat-rate use packages as is customary today.

EDGE (Enhanced Data rates for GSM Evolution) technology (often called 2.75G) was developed in early 2000s enhanced version of GPRS. EDGE is sometimes also called Enhanced GPRS or simply EGPRS.

GPRS technology was standardized by the European Telecommunications Standard Institute (ETSI).

GPRS and EDGE deployments are both managed under the oversight of the 3rd Generation Partnership Project (3GPP).

Features of GPRS

GPRS utilizing packet switching for data transmission. It operates at extremely slow speeds by today's standards - data rates for downloads range from 28 Kbps up to 171 Kbps, with upload speeds even lower.

(In contrast, EDGE supported download rates of 384 Kbps when first introduced, later enhanced up to about 1 Mbps.)

Other features supported by GPRS include:

i) Short Message Service (SMS) - special-purpose communication protocols designed for text messaging
ii) Multimedia Messaging Service (MMS) - extensions to SMS to enable transmission of videos in addition to text
iii) Wireless Application Protocol (WAP) - a specialized communication protocol for mobile browsers, now obsolete

Deploying GPRS to customers required adding two specific kinds of hardware to existing GSM networks:

i) the Gateway GPRS Support Node (GGSN) connects the service provider's cell network to the Internet (or other IP network). These devices manage traffic between the internal and external networks.
ii) the Serving GPRS Support Node (SGSN) sits between the service provider's internal network and the customer-facing equipment (primarily base stations). These devices authenticate and manage phones signed onto the network (including usage monitoring).

The GPRS Tunneling Protocol (GTP) supports the transfer of GPRS data through the existing GSM network infrastructure. GTP primary runs over User Datagram Protocol (UDP).

Using GPRS

To use GPRS, a person must have a cell phone and be subscribed to a data plan where the provider supports it.


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#7 2017-09-02 00:57:15

ganesh
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Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

7) Taipei 101 Tower

Visiting the Taipei 101 Tower site should be on your list of things to do in this exciting city. Beautiful in spirit and design, one notices immediately that its spire is architecturally influenced by the bamboo plant, native to China.

Taipei 101 Tower was the tallest building in the world from 2004 to 2010, when it was surpassed in height by Burj Dubai.

A mall is found at the base, and visitors can shop after visiting the tower. Upscale shopping as well as a supermarket are all part of the excitement. Built to withstand earthquakes and typhoons, the architectural marvel of Taipei 101 Tower will make your visit to Taipei a truly memorable experience.

About Taipei 101

With a height of 1667 feet or 508 meters, Taipei 101 has the distinction of being the third tallest building in the world, and tallest outside the Middle East. Its spire adds to its height, and the total makes it higher than the Kuala Lumpur Petronas Twin Towers. The name, Taipei 101, is derived from the fact that the building encompasses 101 floors.

It was originally known as the Taipei International Financial Center. Fast moving elevators whisk the tenants to their floors, as well as visitors to the observation deck on the 89th floor in 37 seconds. It is considered the second fastest elevator in the world and is a must-do on any traveler's list.

Symbolism in the Design

Influenced throughout by the spirit and culture of the Chinese, the first thing one notices about Taipei 101 is the influence of bamboo on the outside spire. The pagoda shape is also very evident inside and outside.

The number eight, considered lucky in Chinese culture, has been incorporated by the use of eight sections of the outside building.

Observation Deck and Restaurant

You will enjoy a trip up on the high speed elevator at 55 feet per second and the marvelous views of Taipei; then dine at the highest restaurant in the country, Ding Xian 101. Reservations should be made to secure a table.

On the 35th floor, Elly's Flower & Cafe is found and is known for their marvelous coffee and tea as well as western style lunches and dinners. Two more unique restaurants can be found on the 85th floor.

Getting There

Located in the heart of the city, the Tower is surrounded by department stores, a theater, businesses and a skywalk. The area is a short walk from the MRT station of City Hall on the Blue Line. On foot, it usually takes 15 to 20 minutes from the station; Taipei 101 Tower is located on Hsinyi Road.

Admission

The price of general admission to the indoor observation deck is NT$350. Children below the height of 100cm are admitted free. Concession tickets are $320.

If you are interested in accessing the outdoor observation deck, that is an additional NT$100 and is a separate ticket. One must purchase the indoor observation deck ticket as well as outdoor deck if they wish to visit the outdoor deck.

Both observation decks are open from 10 a.m. until 10 p.m.

tap02_img01.jpg


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#8 2017-09-03 23:09:06

ganesh
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Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

8) Fear of falling

The fear of falling (FOF), also referred to as basophobia (or basiphobia), is a natural fear and is typical of most humans and mammals, in varying degrees of extremity. It differs from acrophobia (the fear of heights), although the two fears are closely related. The fear of falling encompasses the anxieties accompanying the sensation and the possibly dangerous effects of falling, as opposed to the heights themselves. Those who have little fear of falling may be said to have a head for heights. Basophobia is sometimes associated with astasia-abasia, the fear of walking/standing erect.

In humans

Infants

Studies done by psychologists Eleanor J. Gibson and Richard D. Walk have further explained the nature of this fear. One of their more famous studies is the "visual cliff". Below is their description of the cliff:

…a board laid across a large sheet of heavy glass which is supported a foot or more above the floor. On one side of the board a sheet of patterned material is placed flush against the undersurface of the glass, giving the glass the appearance as well as the substance of solidity. On the other side a sheet of the same material is laid upon the floor; this side of the board thus becomes the visual cliff.

Thirty-six infants were tested in their experiments, ranging from six to fourteen months. Gibson and Walk found that when placed on the board, 27 of the infants would crawl on the shallow side when called by their mothers; only three ventured off the "edge" of the cliff. Many infants would crawl away from their mothers who were calling from the deep end, and some would cry because they couldn’t reach their mothers without crossing an apparent chasm. Some would pat the glass on the deep end, but even with this assurance would not crawl on the glass. These results, although unable to prove that this fear is innate, indicate that most human infants have well developed depth perception and are able to make the connection between depth and the danger that accompanies falling.

Elderly persons

For a long time, the fear of falling was merely believed to be a result of the psychological trauma of a fall, also called "post-fall syndrome". This syndrome was first mentioned in 1982 by Murphy and Isaacs, who noticed that after a fall, ambulatory persons developed intense fear and walking disorders. Fear of falling has been identified as one of the key symptoms of this syndrome. Since that time, FOF has gained recognition as a specific health problem among older adults. However, FOF was also commonly found among elderly persons who had not yet experienced a fall.

Prevalence of FOF appears to increase with age and to be higher in women. Age remains significant in multiple logistic regression analyses. The results of different studies have reported gender as a somewhat significant risk factor for fear of falling. Other risk factors of fear of falling in the elderly include dizziness, self-rated health status, depression, and problems with gait and balance.

In animals

Studies of nonhuman subjects support the theory that falling is an inborn fear. Gibson and Walk performed identical experiments with chicks, turtles, rats, kids, lambs, kittens, and puppies. The results were similar to those of the human infants, although each animal behaved a little differently according to the characteristics of its species.

The chicks were tested less than 24 hours after birth. It suggested that depth perception develops quickly in chickens, as the chicks never made the "mistake" of walking off the "deep" side of the cliff. The kids and lambs were also tested as soon as they could stand on their own. During the experiment, no goat or lamb ever stepped onto the glass of the deep side. When placed there, the animals displayed typical behavior by going into a posture of defense, with their front legs rigid and their back legs limp. In this state of immobility, the animals were pushed forward across the glass until their head and field of vision crossed the solid edge on the opposite side of the cliff; the goats and lambs would then relax and proceed to spring forward upon its surface. Based on the results of the animals tested, the danger and fear of falling is instilled in animals at a very young age.

Factors that influence the fear of falling

Postural control

The postural control system has two functions: to ensure that balance is maintained by bracing the body against gravity, and to fix the orientation and position of the features that serve as a frame of reference for perception and action with respect to the external world. Postural control relies on multisensory processing and motor responses that seem to be automatic and occur without awareness. Studies have shown that people afraid of heights or falling have poor postural control, especially in the absence of strong visual cues. These individuals rely heavily on vision to regulate their posture and balance.  When faced with high or unstable ground, the vestibular system in these individuals senses the instability and attempts to correct it by increasing postural sway to reactivate visual balance feedback (postural sway refers to the phenomenon of constant displacement and correction of the position of the center of gravity within the base of support). This often fails, however, resulting in a feeling of increased instability and anxiety, which is often interpreted as fear.

Height vertigo

Closely related to postural control is the sensation of vertigo: a warning signal created by a loss of postural control when the distance between the observer and visible stationary objects becomes too large, and caused by a dysfunction of the vestibular system in the inner ear. In short, it is the feeling of motion when one is actually stationary. Symptoms of vertigo include dizziness, nausea, vomiting, shortness of breath, and the inability to walk or stand. Some individuals are more reliant on visual cues to control posture than others. Vestibular sensations can arise when unsound information is detected along the sensory channels (this happens even to those with normal vestibular function), and feelings of vertigo can result in people with postural control issues.

Space and motion discomfort

Studies have shown that people with acrophobia and/or an extreme fear of falling have higher scores of SMD, or space and motion discomfort. These are physical symptoms elicited by visual or kinesthetic information that is inadequate for normal spatial orientation. Space and motion discomfort arises when conflicting information is detected among visual, kinesthetic, and vestibular sensory channels. Evidence has supported the claim that patients with anxiety and SMD rely more heavily on visual cues for postural changes.

Falling in dreams

According to Sigmund Freud's The Interpretation of Dreams, falling dreams fall under the category of "typical dreams", meaning the "dreams which almost everyone has dreamt alike and which we are accustomed to assume must have the same meaning for everyone". In the fairly recent study, "The Typical Dreams of Canadian University Students", common dreams were investigated by administering a Typical Dreams Questionnaire (TDQ). The results confirmed that typical dreams are consistent over time, region, and gender, and a few themes can be considered almost universal: falling (73.8% prevalence), flying or soaring in the air (48.3%) and swimming (34.3%). In 1967, Saul and Curtis published a paper entitled "Dream Form and Strength of Impulse in Dreams of Falling and Other Dreams of Descent". According to Saul and Curtis, dreams of falling can have various meanings, such as the sensation of falling asleep, the symbolization of a real risk of falling from bed, the repetition of traumatic experiences of falling or sensations of falling from parents’ arms in childhood, birth and delivery, ambition or the renouncement of responsibility, or life experiences such as flying in an airplane. They quote another author, Gutheil (1951), who suggests a range of possible meanings subsumed under the general idea of loss of (mental) equilibrium. These include loss of temper, loss of self-control, yielding, decline of the accepted moral standard or loss of consciousness. Studies performed in recent years on the dream patterns of a group of 685 students attending secondary schools in Milan have concluded that, in dreams, fear is more frequently associated with falling, while happiness is connected with flying, and surprise with suspension and vertical movement (climbing, descent, ladder) content.

Media treatment

In the Alfred Hitchcock film Vertigo, the hero, played by James Stewart, has to resign from the police force after an incident which causes him to develop both acrophobia and vertigo. Early on in the film he faints while climbing a stepladder. There are numerous references throughout the film to fear of heights and falling.


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#9 2017-09-05 02:10:31

ganesh
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Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

9) 20 Facts About Burj Khalifa

Burj Khalifa - world’s tallest building is marvel of architectural genius of 21st century. Talk of its height or look at its design, this building is all set to leave you awestruck! Breaking several records and bagging new world records, this building sets global standards for affluence. Here are 20 interesting facts about Burj Khalifa that will make you utter only one word – “awesome!”.

1. Burj Khalifa is the tallest building in the world with an architectural height of 2716.5 feet or 828.0 meters. Its occupied height (height of the floor occupied by people) is 1918 feet or 584.5 meters. Its total height measured from its tip is 2723 feet or 829.8 meters.

2. The observatory deck of the building is located at a height of 1483 feet or 452.1 meters.

3. There are 163 floors located above the ground and it has only one floor located below the ground. It has 58 functional elevators that run at a top speed of 10 meters per second. Burj Khalifa boast 2957 parking spaces, 304 hotels and 900 apartments.

4. The Gross Floor Area of the tower is 3,331,140 ft or 309,473 m². The Gross Floor Area is the area within the footprint of the tower and does not include connected buildings and adjoining podiums.

5. The developer/owner of the tower is Emaar and its design architect is Skidmore Owings & Merill and architect of record is Hyder Consulting.

6. MEP (mechanical, electrical and plumbing) engineer as well as structural engineer is Skidmore Owings & Merill.

7. Turner Construction was the project manager for Burj Khalifa while Besix, Arabtec and Samsung C&T Corporation were its main contractors. Dow Corning Corporation supplied sealants for the tower while Otis Elevator Company supplied the elevators.

8. Located in Dubai, United Arab Emirates, this tower was initially named as Burj Dubai. The building was proposed in 2003 but construction work started in 2004 and was completed in 2010.

9. Burj Khalifa is the tallest tower in Dubai, UAE, Middle East and World. It is 3 times as tall as Eiffel Tower and two times taller than Empire State Building.

10. The tower also holds world records for: ‘tallest free standing building’, ‘highest occupied floor’, ‘highest number of stories’, ‘longest travel distance elevators’, ‘tallest service elevator’ and ‘second highest outdoor observatory deck’. Record for highest outdoor observation deck is now held by Canton Tower which was officially opened in December 2011.

11. Total aluminum used in the tower weighs as much as 5 A380 aircraft. Total concrete used in the tower weighs as much as 100,000 elephants.

12. During peak construction days, 12,000 workers were engaged every day.

13. ’22 million man-hours’, ‘55,000-ton steel rebar’ and ‘110,000-ton concrete’ were used to complete the construction of the tower in 6 years.

14. Skidmore Owings & Merill is an American architect firm and they developed the structural system called ‘buttressed core’ that supports 163 floors of the building.

15. So much rebar was used in the construction of Burj Khalifa that if they were laid down end-to-end, the total length would be one-quarter of the total way across the globe.

16. 26,000 glass panels cut individually were used to create the exterior of the building. 300 Chinese cladding experts worked together to design a cladding system for the tower that could withstand Dubai’s summer heat.

17. Burj Khalifa requires a supply of 250,000 gallons of water each day and total electricity consumption of the building is equivalent to the electricity consumed by 360,000 bulbs of 100-watt each burning at the same time.

18. The building has a specially designed elevator system for controlled evacuation during emergency situations like security threats or fire.

19. The building has 12 machines of 13 tons each moving along tracks constructed outside the building. 36 cleaners board these machines to clean the 24,000 reflective windows of the tower.

20. The design of the tower is inspired by the shape of Hymenocallis flower. The flower is known for its long petals extending out from its center.

Please note that all heights are measured from the lowest level of open air, significant, pedestrian entrance. Underground floors are not included in the measurement. The total cost of building Burj Khalifa was $1.5 billion.

BurjKhalifa.jpg


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#10 2017-09-06 01:00:20

ganesh
Administrator
Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

10) What is Nanotechnology?

Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers.

Nanoscience and nanotechnology are the study and application of extremely small things and can be used across all the other science fields, such as chemistry, biology, physics, materials science, and engineering.

How it Started

The ideas and concepts behind nanoscience and nanotechnology started with a talk entitled “There’s Plenty of Room at the Bottom” by physicist Richard Feynman at an American Physical Society meeting at the California Institute of Technology (CalTech) on December 29, 1959, long before the term nanotechnology was used. In his talk, Feynman described a process in which scientists would be able to manipulate and control individual atoms and molecules. Over a decade later, in his explorations of ultraprecision machining, Professor Norio Taniguchi coined the term nanotechnology. It wasn't until 1981, with the development of the scanning tunneling microscope that could "see" individual atoms, that modern nanotechnology began.

Fundamental Concepts in Nanoscience and Nanotechnology   

It’s hard to imagine just how small nanotechnology is. One nanometer is a billionth of a meter, or

of a meter. Here are a few illustrative examples:

There are 25,400,000 nanometers in an inch

A sheet of newspaper is about 100,000 nanometers thick

On a comparative scale, if a marble were a nanometer, then one meter would be the size of the Earth

Nanoscience and nanotechnology involve the ability to see and to control individual atoms and molecules. Everything on Earth is made up of atoms - the food we eat, the clothes we wear, the buildings and houses we live in, and our own bodies.

But something as small as an atom is impossible to see with the naked eye. In fact, it’s impossible to see with the microscopes typically used in a high school science classes. The microscopes needed to see things at the nanoscale were invented relatively recently - about 30 years ago.

Once scientists had the right tools, such as the scanning tunneling microscope (STM) and the atomic force microscope (AFM), the age of nanotechnology was born.

Although modern nanoscience and nanotechnology are quite new, nanoscale materials were used for centuries. Alternate-sized gold and silver particles created colors in the stained glass windows of medieval churches hundreds of years ago. The artists back then just didn’t know that the process they used to create these beautiful works of art actually led to changes in the composition of the materials they were working with.

Today's scientists and engineers are finding a wide variety of ways to deliberately make materials at the nanoscale to take advantage of their enhanced properties such as higher strength, lighter weight, increased control of light spectrum, and greater chemical reactivity than their larger-scale counterparts.


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#11 2017-09-09 00:47:35

ganesh
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Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

11) Sydney

Sydney is the state capital of New South Wales and the most populous city in Australia and Oceania. Located on Australia's east coast, the metropolis surrounds the world's largest natural harbour and sprawls about 70 km (43.5 mi) on its periphery towards the Blue Mountains to the west, Hawkesbury to the north and Macarthur to the south. Sydney is made up of 658 suburbs, 40 local government areas and 15 contiguous regions. Residents of the city are known as "Sydneysiders". As at June 2016 Sydney's estimated population was 5,029,768.

The Sydney area has been inhabited by indigenous Australians for at least 30,000 years. Lieutenant James Cook first landed at Kurnell in 1770, when navigating his way up the east coast of Australia on his ship, HMS Endeavour. It was not until 1788 when the First Fleet, which contained convicts and was led by Captain Arthur Phillip, arrived in Botany Bay to found Sydney as a penal colony, the first European settlement in Australia. Phillip named the city "Sydney" in recognition of Thomas Townshend, 1st Viscount Sydney, Home Secretary in 1788. There are examples of rock art and engravings located in the protected Ku-ring-gai Chase National Park, as well as the Royal National Park.

Since convict transportation ended in the mid-19th century, the city has transformed from a colonial outpost into a major global cultural and economic centre. The municipal council of Sydney was incorporated in 1842 and became Australia's first city. Gold was discovered in the colony in 1851 and with it came thousands of people seeking to make money.  Sydney became one of the most multicultural cities in the world after the mass migration following the second World War. According to the 2011 census, more than 250 different languages were spoken in Sydney and about 40 percent of residents spoke a language other than English at home. Furthermore, 36 percent of the population reported having been born overseas.

Despite being one of the most expensive cities in the world, the 2014 Mercer Quality of Living Survey ranks Sydney tenth in the world in terms of quality of living, making it one of the most livable cities. It is classified as an Alpha World City by Globalization and World Cities Research Network, indicating its influence in the region and throughout the world. Ranked eleventh in the world for economic opportunity, Sydney has an advanced market economy with strengths in finance, manufacturing and tourism. There is a significant concentration of foreign banks and multinational corporations in Sydney and the city is promoted as one of Asia Pacific's leading financial hubs. Established in 1850, the University of Sydney is Australia's first university and is regarded as one of the world's leading universities.

In addition to hosting events such as the 2000 Summer Olympics, Sydney is amongst the top fifteen most-visited cities in the world, with millions of tourists coming each year to see the city's landmarks. Its natural features include Sydney Harbour, the Royal National Park, and the Royal Botanic Garden. Man-made attractions such as Sydney Tower, the Sydney Harbour Bridge, and the Sydney Opera House (which became a World Heritage Site in 2007), are also well known to international visitors. The main passenger airport serving the metropolitan area is Kingsford-Smith Airport, one of the world's oldest continually operating airports. Opened in 1906, Central station is the main hub of the city's rail network.

2942.jpg


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#12 2017-09-10 00:40:02

ganesh
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Registered: 2005-06-28
Posts: 23,209

Re: Miscellany

12) July 12, 1962: The Day Information Went Global

Telstar was launched by NASA on July 10, 1962, from Cape Canaveral, Fla., and was the first privately sponsored space-faring mission. Two days later, it relayed the world's first transatlantic television signal, from Andover Earth Station, Maine, to the Pleumeur-Bodou Telecom Center, Brittany, France.

Developed by Bell Telephone Laboratories for AT&T, Telstar was the world's first active communications satellite and the world's first commercial payload in space. It demonstrated the feasibility of transmitting information via satellite, gained experience in satellite tracking and studied the effect of Van Allen radiation belts on satellite design. The satellite was spin-stabilized to maintain its desired orientation in space. Power to its onboard equipment was provided by a solar array, in conjunction with a battery back-up system.

Although operational for only a few months and relaying television signals of a brief duration, Telstar immediately captured the imagination of the world. The first images, those of President John F. Kennedy and of singer Yves Montand from France, along with clips of sporting events, images of the American flag waving in the breeze and a still image of Mount Rushmore, were precursors of the global communications that today are mostly taken for granted.

Telstar operated in a low-Earth orbit and was tracked by the ground stations in Maine and France. Each ground station had a large microwave antenna mounted on bearings, to permit tracking the satellite during the approximately half-hour period of each orbit when it was overhead. The signals from Telstar were received and amplified by a low-noise "maser" (Microwave Amplification by Stimulated Emission of Radiation), the predecessor of the modern laser. After demonstrating the feasibility of the concept, subsequent communications satellites adopted a much higher orbit, at 22,300 miles above the Earth, at which the satellite's speed matched the Earth's rotation and thus appeared fixed in the sky. During the course of its operational lifespan, Telstar 1 facilitated over 400 telephone, telegraph, facsimile and television transmissions. It operated until November 1962, when its on-board electronics failed due to the effects of radiation.

telstar.jpg


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#13 2017-09-16 15:46:12

ganesh
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Re: Miscellany

13) The Element Osmium

Atomic Number: 76
Atomic Weight: 190.23
Melting Point: 3306 K (3033°C or 5491°F)
Boiling Point: 5285 K (5012°C or 9054°F)
Density: 22.57 grams per cubic centimeter or 22,570 kilograms per meter cube, The heaviest metal
Phase at Room Temperature: Solid
Element Classification: Metal
Period Number: 6    Group Number: 8    Group Name: none

What's in a name? From the Greek word for a smell, osme.

Say what? Osmium is pronounced as OZ-mee-em.

History and Uses:

Osmium and iridium were discovered at the same time by the British chemist Smithson Tennant in 1803. Osmium and iridium were identified in the black residue remaining after dissolving platinum ore with aqua regia, a mixture of 25% nitric acid (HNO3) and 75% hydrochloric acid (HCl). Today, osmium is primarily recovered during the processing of platinum and nickel ores.

Metallic osmium is hard, brittle and very difficult to make. Powdered osmium is easier to make but emits osmium tetroxide (OsO4) when it is exposed to the air. Unfortunately, osmium tetroxide smells bad and is very poisonous. Because of these problems, osmium is primarily used to make very hard alloys. Osmium alloys can be found in ball point pen tips, fountain pen tips, record player needles, electrical contacts and other devices where frictional wear must be minimized.

Estimated Crustal Abundance:

milligrams per kilogram

Estimated Oceanic Abundance: Not Applicable

Number of Stable Isotopes: 5   

Ionization Energy: 8.7 eV

Oxidation States: +4, +3

Electron Shell Configuration:






osmium.jpg


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#14 Yesterday 01:38:17

ganesh
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Posts: 23,209

Re: Miscellany

14) Amoeba

Amoeba, also spelled ameba, plural amoebas or amoebae, any of the microscopic unicellular protozoans of the rhizopodan order Amoebida. The well-known type species, Amoeba proteus, is found on decaying bottom vegetation of freshwater streams and ponds. There are numerous parasitic amoebas. Of six species found in the human alimentary tract, Entamoeba histolytica causes amebic dysentery. Two related free-living genera of increasing biomedical importance are Acanthamoeba and Naegleria, strains of which have been recognized as disease-causing parasites in several vertebrates, including humans.

Amoebas are identified by their ability to form temporary cytoplasmic extensions called pseudopodia, or false feet, by means of which they move about. This type of movement, called amoeboid movement, is considered to be the most primitive form of animal locomotion.

Amoebas are used extensively in cell research for determining the relative functions and interactions of the nucleus and the cytoplasm. Each amoeba contains a small mass of jellylike cytoplasm, which is differentiated into a thin outer plasma membrane, a layer of stiff, clear ectoplasm just within the plasma membrane, and a central granular endoplasm. The endoplasm contains food vacuoles, a granular nucleus, and a clear contractile vacuole. The amoeba has no mouth or math; food is taken in and material excreted at any point on the cell surface. During feeding, extensions of cytoplasm flow around food particles, surrounding them and forming a vacuole into which enzymes are secreted to digest the particles. Oxygen diffuses into the cell from the surrounding water, and metabolic wastes diffuse from the amoeba into the surrounding water. A contractile vacuole, which removes excess water from the amoeba, is absent in most marine and parasitic species. Reproduction is asexual (binary fission).

During adverse environmental periods many amoebas survive by encystment: the amoeba becomes circular, loses most of its water, and secretes a cyst membrane that serves as a protective covering. When the environment is again suitable, the envelope ruptures, and the amoeba emerges.

Amoeba-stationary-form.jpg


It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi. 

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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