Thursday, 25 November 2021

A White Great Shark

A great white shark attacks from A Seton and behind, taking its victim by surprise. To do this it has to come up fast and keep its quarry in sight. Its eves must react rapidly to the change in light if its hunt is to be successful. Like all other sharks, the great white relies on its array of senses to locate prey such as seals and sea lions. But its sight is crucial to pinpointing a victim at the surface. Silhouetted against the light just as a human, entering a brightly lit room from the darkness outside, can be briefly dazzled and take 2 few seconds to adjust to the change, so a shark, rising to the surface from the murky depths must cope with a rapid increase in light. It cannot afford to wait for its eves to adjust — a lost second and the prey could be gone.

The secret of this ability lies in the tapetum, a laver of mirror-like plates at the back of the eyeball. It is the tapetum that eerily lights up the cat’s eyes when it is caught in Car headlamps at night. By reflecting light back through the retina, it effectively doubles the amount of light for the eye to use. This is essential for night hunters, like the cat. if they are to see with clarity, especially in the faint moonlight. In the day, though, too much light can be a problem. The cat copes by narrowing its pupil, the gap that Jets in light, to 4 wafer-thin slits, using the muscles in the iris.

The great white shark's tapetum greatly enhances its vision in the murky depths, but it has no iris to protect its eyes when it surfaces rapidly. In order to compensate, it has developed a ‘curtain’ of cells containing pigment. As the shark moves into bright light, these automatically expand over each tapetal plate and then contract as it returns to the depths.

While it is swimming in shallow water, a shark needs to be able to see into the light above it and into the dark below. In this case, the tapetal curtain reacts differently in each half of the eye. The lower half-eye of a killer whale hunting deep in the ocean, a blue shark relies upon reflective plates behind its eyeballs to increase the amount of light striking the retina. of the tapetum, which reflects light from above, is covered to protect the retina. The upper half of the tapetum, which reflects light from below, is exposed to make the most of the light hitting the retina and so give as clear a picture as possible of the murky depths below. 

Wednesday, 13 October 2021

The Guerrilla Warfare

 Those seeking historical insights into counterinsurgency warfare will find Roger Trinquier’s classic modern Warfare: A French View of Counterinsurgency disturbingly current. First published in 1961 and one of the best-selling post-World War II books in France, Trinquier influenced a generation of counterinsurgency scholarship. He succeeded in describing the true face of what current observers also label “modern war.”

Nearly 40 years later, for example, Mark Bowden subtitled his bestsellerBlack Hawk Down, the story of a US Special Forces operation in Somalia gone awry, A Story ofModern War. Despite important differences between Somalia and the colonial independence conflicts Trinquier participated in, ongoing operations in Afghanistan and Iraq reflect many of the nonlinear, unconventional elements of what Trinquier labeled modern war to distinguish between armored battles between nation-states and counterinsurgencies pitting nation-builders against organizations using terrorist tactics.

Trinquier was introduced to counterinsurgency warfare in  Indo-china before being assigned to Algeria in 1957 as a Lieutenant Colonel with the  French  10th  Parachute  Division.  Decades of service conditioned his views. Algeria inspired his writings on modern war, including a penetrating testimony to the central tenet of counterinsurgency: winning the allegiance of the indigenous population. A systematic approach is needed.

Counterinsur-gencies require “an interlocking system of actions political, economic, psychological, the military that aims at the [insurgents’ intended] overthrow of the established authority in a country and its replacement by another regime.” As a military theory, Trinquier’s “modern war” parallels a prominent theme in post-Cold War military thought, one documented by Israeli military historian  Martin  Van  Creveld’s  1991  book, The  Transformation of  War.

Trinquier preceded Van Creveld and other post-Cold War military theorists in arguing that nuclear weapons would lead to a decline in traditional armored warfare and a rise in modern warfare in its many variants: guerrilla warfare, insurgency, terrorism, and subversion.

As do currently military analysts, Trinquierapproached the problem of countering modern warfare by assessing differences between linear clashes of armies and the tactics, goals, methods, and norms of the insurgent or guerrilla. Pitting a traditional combined armed force trained and equipped to defeat similar military organizations against insurgents “reminds one of a pile driver attempting to crush a fly, indefatigably persisting in repeating its efforts.”

In Indochina, for For example, the French “tried to drive the Vietminhinto a classic pitched battle, the only kind knew how to fight, in hope that superiority in material would allow an easy victory.” The only way to avoid similar pitfalls, according to Trinquier is to fight the “specially adapted organization” that is common to almost all subversive, violent movements seeking to overthrow the status quo.

In October 2003 it appeared the UnitedStates was creating its special organization to combat Iraqi insurgents: Task Force 121, a new joint strike unit reportedly composed of American special Forces units and Army Rangers.7Presumably steeped in counterinsurgency warfare, Task Force 121and other units operating against The Iraqi resistance has learned the lessons of past modern wars. They will not simply sweep towns.

This won’t defeat an organized insurgency. Instead, the enemy’s organization must be targeted to de-feat the clandestine organization attempting to impose its will on the Iraqi people. Four elements typically encompass an insurgency: cell networks that maintain secrecy; terror used to foster insecurity among the population and drive them to the movement for protection; multifaceted attempts to cultivate support in the general population, often by undermining the new regime; and attacks against the government.

Only by identifying and destroying the infrastructure of the subversive organization can the fledgling government perseveres. Stated another way, just as the traditional war is not fought with the individual soldier or platoon in mind but rather the state’s capacity and will continue hostilities, modern war seeks to destroy the organization as a whole and not simply its violent arm or peripheral organs.

After comparing the relative resources of the insurgent and government forces, Trinquier concludes “that the guerrilla’s greatest advantages are his perfect knowledge of an area (which he has chosen) and its potential and the support gave him by the inhabitants.” To turn this defeat into a victory, the counterinsurgent must recognize that “this total dependence upon terrain and population is also the guerrilla’s weak point.”

Toward this end, he suggests three simple principles: separate the guerrilla from the population that supports him; occupy the zones that the guerrillas previously operated from, making them dangerous for him and turning the people against the guerrilla movement; and coordinate actions over a wide area and for a long enough time that the guerrilla is denied access to the population centers that could support him.

This requires an extremely capable intelligence infrastructure endowed with human sources and deep cultural knowledge.  Indeed,  intelligence is key. As the Commander of the US Army’s 1st Armored Division in Iraq, Major General Martin Dempsey, observed in November 2003, “Fundamentally, here in Baghdad we do two things: We’re either fighting for intelligence or we’re fighting based on that intelligence.”

Despite unparalleled improvements in military intelligence, the United States does not seem to have the depth and breadth required in human intelligence (humint) and cultural intelligence arenas. Arabic linguists are lacking. Undersecretary of Defense for Intelligence Stephen Cambone, discussing intelligence shortcomings documented in an internal report, might have understated the problem, admitting, “We’re a little short on the humint side; there’s no denying it.”

For Trinquier, intelligence was one of several crucial enablers for de-feating an insurgent. Others included a secure area to operate from, sources in the general population and government, maintaining the initiative, and careful management of propaganda.

A critical step in any counterinsurgency campaign is the creation of a“tight organization” to counter the enemy’s organizational advantages. Created from the bottom up, based on a full appreciation for the tactical situation, a successful counterinsurgency organization must depart from their standard operational approach to warfare.

For example, campaign planning should include a system to account for every citizen, coordination with the political ef-fort to designate a hierarchical network of groups headed by pro-government chiefs, and a system to monitor the activities of guerrilla sympathizers. This entails a census, the issuing of photo-identification cards, and a countrywide intelligence system. The ultimate goal is to separate the fish from the sea, leaving it exposed to the state’s spear.

Thursday, 30 September 2021


RECOGNITION Black body mottled with yellow, especially laterally. Long, black, shiny spines arise from irregular blackened patches. On midabdominal segments each seta arises from its own blackened plate, except above spiracle, where two setae share single plate. Larva to 3.5cm. Painted Lichen Moth (Hypoprepia fucosa) smaller, marked with less yellow; middorsal stripe less differentiated (inset).

OCCURRENCE Woodlands and forests from southern Canada to Florida and Texas. One generation with mature caterpillars from May to July northward; two or three generations in Missouri with mature caterpillars nearly year-round.

COMMON FOODPLANTS Lichens and blue-green algae (cyanobacteria) growing

on tree trunks, fallen logs, and rocks.

REMARKS Adults of eastern Hypoprepia vary considerably in different parts of the Southeast, so much so that some lepidopterists feel additional species will eventually be recognized. Hypoprepia and other lithosiine arctiids have anal combs that allow them to eject their fecal pellets distances of 30 or more body lengths. 

The comb, which protrudes from the underside of the anal plate, is hooked under a torus of rectal tissue. Hemolymph (blood) is then forced to the last body segment, where pressure becomes so great that the comb slips and the fecal pellet is ejected with great velocity. “Fecal flicking” foils parasitic and predatory wasps that would use volatiles from the excreta to locate their intended victims.  Hypoprepia caterpillars are cannibalistic on smaller larvae and pupae. The caterpillar overwinters.

Saturday, 11 September 2021

Birds for All Seasons

Watching birds is a delightful activity at any time of the year - provided, of course, that the weather conditions are not too severe! Particular habitats or regions may have more to offer at certain times of the year, however, and a little insight and planning can help decide the potentially interesting areas to visit on a trip at any particular season. Birdwatching is an amazingly popular pastime in Britain. Hence, individuals of all ages are involved, and the degree of eagerness and promise ranges from casual appreciation to nothing short of fanatical pursuit. While many are happy to enjoy the birds that they encounter on their travels, 'twitching' or the pursuit of rarities is an increasingly popular form of modern birdwatching. 

This is fueled by the well-developed twitchers' grapevine, which is centered on various recorded- message bird information telephone lines. While finding or seeing unusual species is exciting, it should not detract from the satisfaction to be found in close, careful observation of common species - for birds of all kinds, be they common or rare, are fascinating and more than repay the time spent observing and studying them. Spring is a wonderful season for the birdwatcher. In woodlands everywhere, it heralds the start of the breeding season, and the songs of the resident species are augmented by those of newly arrived migrants. Dawn is the best time for hearing the widest range of birdsong. 

Migrants and the flow of migrating birds are also clearly seen in spring along Britain's seashores, where headlands and estuaries offer excellent opportunities to see the birds. Summer is a comparatively quiet time of year for the birdwatcher. although not without its highlights. Family parties of songbirds may be found in woods and hedgerows - those migrant species feeding eagerly on ripening berries are storing energy for their forthcoming travels. 

Lakes and reservoirs often attract large numbers of swallows, martins, and swifts which feed on the the abundance of insect life, while estuaries around the coast witness the first gatherings of migrating waders and wildfowl. This is probably the liveliest time to visit seabird colonies on the cliffs: ravenous, fully grown young are being fed continually at this time of the year, so there is plenty of activity. For the birdwatcher with access to the coast, autumn is perhaps the most exciting season: everywhere there are signs of migration and the estuaries begin to fill up with ducks, geese, and waders. 

As the weather deteriorates towards winter, inland birds of many kinds tend to move out to the coast, where the proximity of the sea moderates extremes in the weather. Winter can be an unexpectedly good season for the woodland birdwatcher. The lack of leaves makes observation among trees and bushes relatively easy, and many of the smaller birds band together in roaming flocks, often being joined by winter visitors. Grassy downs, heaths, and marshes can harbor birds of prey at this time of year, and estuaries and wetlands are often outstanding. Birds may appear quite different at changing times of the year and life-cycle. 

Though a puffin is most familiar in its bright adult, summer colors (left and bottom), these illustrations show the changes from four weeks old, at around six weeks, during a first winter, an adult in winter, and an adult in the summertime. No matter in which season, it is always worth keeping a cautious eye on the weather, for abrupt changes or extremes can have a dramatic influence on the numbers and species of birds to be seen. For example, westerly gales in the autumn will initiative migrating seabirds, usually only seen well out to sea, near to the shore, making them easy to observe. 

However, the longer periods of southerly or southeasterly winds in spring can result in admirable conditions for migration, with large numbers of birds arriving overnight; in the autumn these same winds can result in all sorts of interesting and unusual sightings, as birds are blown off their regular migration routes. Sudden and prolonged periods of severe cold in winter can cause large numbers of birds to move towards the warmer south and west of the country, with even more individuals arriving here from Europe.

Monday, 30 August 2021

A Wheel to Watch the Heavens

 High in the Bighorn Mountains of Wyoming, on the stony surface of a windswept plateau, lies the ghostly outline of a spoked wheel eighty-two feet in diameter. Similar rocky circles appear in Saskatchewan, in Arizona, and at some fifty other sites across the North American plains. Some are a few feet in diameter, others are hundreds of times as large. All lie on high ground. 

The wheels are built simply: Thin ridges of stones formation, hub, and usually several spokes. Some have rocky piles, called cairns, in their centers and around the outer circles. The Bighorn medicine wheel - so-called because, to the American Indian, any object with spiritual properties was said to have medicine - is the best preserved and best known.

Historians guess that Plains Indians made this circle as early as the 1100s, but they cannot be certain Not do investigators know the exact purpose of any of the wheels - though clues may lie in their orientation. At the Bigham wheel, for instance, an observer who sights over the cairn in the foreground (above) toward the hub will look into the rising sun on the morning of the summer solstice. A second cairn would mark sunset on the same day. Other rock piles point to the rising and setting of three brilliant stars during seasonal changes.

Such alignments lead some theorists to believe that the medicine wheels like their huge megalithic cousins in Europe, were in fact astronomical observatories. This contention is strengthened by the fact that all such wheels are carefully positioned to offer clear views of the horizon. Furthermore, cairns in some wheels cover postholes that may have held upright timbers, so that the original sites would have looked almost like wooden versions of Stonehenge in England.

But critical questions remain. Why would Plains Indians need to watch the sky? Agricultural tribes might have wanted to keep track of growing seasons, but the nomadic Plains peoples lived by hunting bison. Could they have remembered an earlier age when they planted crops? Or did the solstice mark the turning point of the summer for them, a time to begin counting the days until the start of their southward migration?

Such questions may never be answered. Like the builders of so many of the earth's markings, those who laid out the medicine wheels have vanished, leaving later generations no key to their strange monuments. Desert. Near the small town of Blythe, California, he happened to glance down at the arid landscape. I could hardly believe what 1 saw," he said later. Sprawled across the desert, far from civilization, were the gigantic figures of a man and a long-tailed animal.

Reports of the so-called Blythe Giant continued in the decades to come, prompting scientists and other investigators to take a closer look at the little-known southwestern desert. There, along the arid lower valley of the Colorado River, they have discovered some 275 geoglyphic, obscure symbols, and bizarre, childlike drawings of humans and animals. The Mojave's surface, like that of the Nazca desert, is covered with rocks varnished to a dark sheen by the sun, apparently, the Mojave artists used the same rock-removal technique as the Nazcas to create their enigmatic messages.

Most of these desert markings have been discovered since the 1970s, thanks to the tireless efforts of California archeologist Jay von Werlhor and his collaborator, a local farmer and pilot named Harry Casey. By plane and foot, they have reconnoitered thousands of square miles of the blistering ground that early Spanish explorers called tierra del muerto, "land of the dead." The collaborators' goal is to catalog and describe every desert marking in this vast region. "It's absolutely addictive," Casey has said of his quest. "the more you learn, the more you want to know."

Von Werlhof and his fellow archeologists believe the figures found on the Mojave were created for mystic purposes by the Indians who have inhabited the desert for more than 5,000 years. The date the oldest of the figures to 3000 Bc and the most recent of them to the late eighteenth century AD More primitive configurations, known as rock alignments-twisting lines of boulders set side by side in abstract patterns -may be as much as 10,000 years old.

The investigators offer several interpretations of the weird tableau at Blythe, whose age is variously estimated at between 200 and 1,000 years. According to legends passed down by the Mojave Indians, the manlike form represents an evil giant who terrorized their ancestors. The animal figure, which seems to float upside down over the man's head, is said to be a mountain lion imbued with great power from the Mojave's creator god, it was placed there to weaken the giant's spirit. A less dramatic theory suggests that the giant is a kind of graphic "no trespassing" sign placed by Hopi Indians to keep intruders out of their territory.

Many of the animal figures seem to have retained a spiritual significance to the desert dwellers. A 180-foot-long rattlesnake with basalt eyes, according to Mojave medicine men, has powers of good or evil that can be passed onto humans. A figure near Yuma, Arizona is clearly that of a horse, an animal unknown to the southwestern Indians before the coming of Europeans. 

Archeologists believe that the Indians created the image sometime after Spanish explorers rode through the area in 1540 and that they subsequently used the desert drawing as a ceremonial meeting place. Another figure, not discovered until July 1984, is a startlingly animated rendering of a fisherman who appears to be dancing on the water while aiming a spear at two fish. The tip of the spear is made of hundreds of pieces of glittering quartz and may have been designed to bestow magic powers on real fishermen.

Like their counterparts at Nazca, the Mojave figures apparently served a variety of purposes, and at least some of the drawings may have been astronomical markers. A rock alignment along the Gila River in Ari zona, for example, points precisely to the sunrise at the summer solstice. Another, known as the Black Point Dance Circle, may have been designed as a map of the sun, moon, and Milky Way. Knowledge of the heavens could have given Indians a calendar with which to plan their farming and irrigation-vital information in a difficult environment.

Whatever the purpose of their elaborately drawn geoglyphic, the Indians of the Nazca and Mojave deserts were blessed with ideal natural blackboards upon which to scratch out their designs. The natives of the temperate forests of the American Midwest and South was not so fortunate, but they still managed to mark the landscape with impressive animal figures Like their desert counterparts, these images can best be appreciated from the air. 

Sunday, 30 May 2021

Genus Micrustur

The genus Micrustur is a distinct group of six species of small to large falcons with long tails and short wings that inhabit forests from southern Mexico to Central Argentina. Little information exists on the natural habits of its members; indeed even nidification remains unknown (Brown and Amadon, Eagles, hawks and falcons of the world, I discovered a nest of the Collared Forest Falcon (M. semitorquatus) in a canopied forest (estimated to be 20-40 m high) in southwestern Guarico state, Venezuela. The nest was 12 m from the ground in the cavity of a 38-m tree (determined from a clinometer).

The Cuarico River was 200-300 m east of the nest. I found the nest around IO:00 h on 20 August 1978 and returned four hours later with three companions and tree climbing gear. I discovered one nearly fledged chick inside the nest cavity. I estimated the cavity to be about 0.50 m deep and 0.60 m wide. There were two openings into the hollow, both well sheltered from the rain and on opposite sides of the tree trunk.

One was round, about 20-30 cm in diameter and at the top of the cavity. The hole appeared to be the place where a limb had broken off and since rotted. I first located the nest by hearing the chick calling and then seeing it peering out through this hole; it was probably the entrance used by the adults. The second entrance to the cavity was a vertical slit about 30 x 20 cm. Looking into the cavity from this opening, I could see no evidence of nesting material on the floor of the cavity so presumably this species of falcon, like most others, lays its eggs in a bare scrape.

The floor of the cavity had vines growing across it while the sides of the cavity were white-washed from falcon droppings. Although I could not see any prey remains, the nest smelled heavily of decaying animal matter. When I tried to grab the chick to obtain measurements and photographs it jumped to the round entrance hole and clumsily flew about 30 m to a tree. After climbing down I looked at the chick through 10 x 50 binoculars. The primaries and rectrices were noticeably short and not fully grown. I believe that this chick was the only one because I did not hear any others calling. I first found this pair of falcons on 16 July. Although

I saw an adult, presumably the female (with an obvious brood patch) I failed to find the nest. This bird walked along horizontal tree limbs and called at me. On subsequent visits I saw little of the adults but often heard them. They uttered two calls. The first appeared to be an alarm call aimed at me and sounded like “ho, ho, ho.” The second call sounded like a single long “ho.” At times an adult gave this call and the chick returned it, but at a different pitch. On other occasions the adults gave this call back and forth to one another.

The fact that the falcons nested roughly between June and August suggests that breeding may usually occur in the wet season (April-November in Guarico). Other forest hawks such as the Roadside Hawk (Buteo mugnirostris), Crane Hawk (Gerunospiza caerulestens), and Bicolored Hawk (Accipiter bicolor) also breed in the wet season (pers. observ.). 


Wednesday, 18 March 2020

Benefits of Forest to People and Animals

Forest provides multiple benefits to the environment, people, and animals. The list of benefits is as follows

·Forest helps in to cool air temperature by release of water vapor into the air.
·At day time trees generate oxygen and store carbon dioxide, which helps to clean air.
·Forest attracts wildlife and offer food and protection to them.
·Forests offer privacy, reduce light reflection, offer a sound barrier and help guide wind direction and speed.
·Trees offer artistic functions such as creating a background, framing a view, complementing architecture, and so on.
·Well managed forests supply higher quality water with less impurity than water from other resources.
·Some forests raise the total water stream, but this is not true for all forests.
·Forests help in controlling the level of floods.
·Forest provides different kinds of wood which are used for different purposes like making furniture, paper, and pencils and so on.
·Forest helps in giving the direction of the wind and its speed.
·Forest helps in keeping the environment healthy and beautiful.
·Forests also minimize noise pollution.
·Forest helps the scientist to invent new medicine as the forest has a different kind of plants and herb.

All benefits quoted above are purely the outcome of forests and cannot be derived from agriculture. If the cost of these is calculated in terms of money, it will be far above the outcome/benefits of agriculture.

Thursday, 20 February 2020

What was Radiometric dating?

The discovery that natural radiant energy was a much more complex phenomenon than previously thought with various sources dates to the last decade of the nineteenth century. In 1895 Rontgen discovered a new kind of radiation, which he called X-rays, and apparently ‘aroused an amount of interest unprecedented in the history of physical science’ according to J. J. Thomson, Head of the Cavendish Laboratory in Cambridge, reporting to professional colleagues the following year.
We now know that it was indeed a remarkable breakthrough and one that was to bring great benefits and dangers that were not initially appreciated, dangers that were also to arise with the other newly discovered forms of radiation. In 1896 the brilliant French physicist Henri Becquerel discovered that crystals of a uranium salt accidentally placed on top of a wrapped and unexposed glass photographic plate caused the plate to blacken as if it had been exposed to light. Becquerel realized that the crystals were spontaneously emitting some unknown type of energy similar but different to X-rays.
The radiation was solely due to the radium and, unlike light energy, could not be reflected. He also discovered that a lump of radium mineral that he carried around in his pocket burned his skin. But it was the young Polish scientist Marie Curie and her French husband Pierre who made a study of these strange ‘Becquerel rays’. Marie Curie made the all-important discovery that the radiant energy emitted by the uranium salt was an inherent property of the element uranium and together with her husband Pierre named the new phenomenon ‘radioactivity’. In addition, Marie Curie found that the element thorium also emitted similar radiation.
When the Curies examined two naturally occurring uranium ores, pitchblende, and chocolate, they discovered that the radiation emitted was more intense than the uranium or thorium content of their ores, indicating the presence of other radioactive elements. Following the laborious separation processes of fractional crystallization, they managed to distinguish the presence of polonium and the much more radioactive uranium. However, it was a brilliant New Zealander, Ernest Rutherford, working with British chemist Frederick Soddy, who made the breakthroughs that were to lead to the development of radiometric dating.
From experiments on thorium compounds in 1902, Rutherford and Soddy discovered that the activity of a substance is directly proportional to the number of atoms present. From this observation, they formulated a general theory that predicted the rates of radioactive decay and went on to suggest that the gaseous element helium might be a ‘decay’ product of a radioactive element.
At that time, it was not known how many elements were radioactive nor what their decay products might be since radioisotopes had yet to be discovered and there was no instrument available that could measure radioactivity. Nevertheless, Rutherford’s brilliant insights allowed him to suggest that radioactivity might be used as a ‘clock’ to date the formation of some naturally occurring minerals and therefore the rocks that contained them. Rutherford had enormous respect for Kelvin and when addressing a meeting that the great man was attending, referred to Kelvin’s 1862 claim that the Sun could not keep shining unless ‘the great storehouse of creation’ contained some unknown source of energy.
Rutherford and others had now discovered that hidden source – the energy emitted by radioactive elements as they decay within the rocks of the Earth, which is enough to counteract and significantly slow down the rate of cooling. He tried to placate Kelvin by portraying the old man’s prophetic and prescient disclaimer as the hallmark of a very great scientist – ‘that prophetic utterance refers to what we are now considering tonight, radium!’ But Kelvin never really accepted the role that radioactive elements played in the creation of the Solar System, a process that we now understand as stellar nucleosynthesis.
In 1905, Rutherford wrote that ‘if the rate of the production of helium by radium (or other radioactive substance) is known, the age of the mineral can at once be estimated from the observed volume of helium stored in the mineral and the amount of radium present’. On this basis, he determined the very first radiometric date for a fergusonite mineral, which gave a Uranium-Helium age of around 497 million years and one of 500 million years for a uraninite mineral from Glastonbury, Connecticut.
But Rutherford wisely cautioned that these were minimum ages because some of the helium gas would undoubtedly have escaped during the processing of the materials. He suggested that calculations based on lead might be superior: if the production of lead from radium is well established, the percentage of lead in radioactive minerals should be a far more accurate method of deducing the age of a mineral than the calculation based on the volume of helium for the lead formed in a compact mineral has no possibility of escape.
In the same year, an American radiochemist, Bertram Boltwood, went on to provide the first reasonably accurate means of dating the formation of certain minerals within the Earth. Boltwood studied at Yale then in Germany and, on returning to America, worked to improve the analytical techniques of radiochemistry pioneered by his friend Rutherford, who at this time was at McGill University in Montreal. Boltwood made a systematic analysis of radioactive uranium-bearing rocks and noticed that generally both helium and lead were present, with the lead being the stable product of the decay chain from uranium.
Boltwood went on to develop a technique that allowed him, with the aid of a Geiger counter, to measure decay rates and with some chemical apparatus to analyses the remaining lead and uranium concentrations and the ratio of the radioactive isotopes. Initially, he tried out his new method on 10 uranium minerals from rocks whose relative geological age was roughly known, publishing the results in 1907.
These samples ranged in age from 2200 million years for a thoriate (thorium and uranium oxide) from Ceylon (now known as Sri Lanka) to 410 million years for uraninite (uranium oxide) from Glastonbury, Connecticut. The oldest date increased the age of the Earth by an order of magnitude. Although by modern standards these results were not very accurate, for instance, the age of the Glastonbury uraninite has been recalculated to 265 Ma, Boltwood’s technical developments were of enormous importance.
Now the physicists really had to take notice and admit that Kelvin was way off the mark. It began to seem that the geologists had been right all the time to argue that the Earth must be much, much older than 20 million years or so. By 1910, a British geologist, Arthur Holmes, was pursuing a similar approach and embarked on a lifetime’s quest ‘to graduate the geological column with an ever-increasingly accurate time scale’.
He calculated the age of a Norwegian rock, which contained several radioactive minerals, like 370 million years. As the rock was known to have originated within the Devonian geological system, he thus provided the first date for that geological system and period. In retrospect, this was the most accurate of the early radiometric dates and, if Holmes had had the resources to continue his work, radiometric dating would have progressed much faster than it did. Holmes also recalculated some of Boltwood’s published data and arranged them to produce the first geological timescale. He was to improve on this scale continuously for the rest of his professional life.

Sunday, 9 February 2020

The History of Chromatography

The term “chromatography” was coined by Mikhail Tsvet drawing on two Greek Roots:  Chroma (‘colour’) and graphein (‘writing’).  But the word might also be a play on the botanist’s own surname, which mean ‘color’ in Russian. According to this interpretation, ‘chromatography’ would literally mean ‘Tsvet’s writing’.

Analytical tool – A scientist uses compasses on a chromatogram to measure the distance travelled by each constituent element of the substance under investigation. This colorized digital image shows the clear separation between the constituents.

Chromatography 1903

Like light rays in the spectrum, the different components of a pigment mixture, obeying a law, are resolved on the calcium carbonate column and can then be qualitatively and quantitatively determined. This is how Russian botanist Mikhail Tsvet attempted to explain chromatography, the method of color analysis that he had invented.

He first presented his finding to scientific peers as early as 1901. However, in 1903, he published an account of them for wider consumption in proceedings of the Warsaw Society of Naturalists.

Although Tsvet was very interested in plant pigments! The problem was having obtained a plant extract, how could it be separated into its constituent elements to facilitate further study? He found the answer quite by chance. Having prepared an extract of spinach with petroleum ether, he filtered the solution by passing it through a column of chalk (Calcium Carbonate) in a vertical glass tube.

As he did so, distinct areas of yellow and green pigment appeared in different parts of the column. Tsvet realized that each pigment had traveled a specific distance before being deposited in the chalk. To obtain pure components of the pigment, all he had to do was to take samples from each color zone. This was the basic principle behind the science of chromatography.

Neglect and Revival

Tsvet’s work excited about some interest. But it was soon forgotten in all the upheaval of the First World War and the Russian Revolution. Tsvet died in 1919, aged just 47. Then, in 1931, two biochemists at the University of Heidelberg, Edgar Lederer and Richard Johann Kuhn, were conducting their own research into plant pigments and resurrected his technique.

Several new methods of chromatography were devised thereafter along essentially the same lines. That is by filtering a liquid or a gaseous compound through a medium – paper for example, or a porous material a gas, an immobilized liquid. That retains each of the separate components at a particular level.

Chromatography has since become an indispensable tool in organic and biochemical research. It is used for example; to detect drugs in athletes' blood samples to isolate a particular ingredient for drug manufacture and more generally to separate analyze and identify different elements within compounds.  
Mikhail Tsvet (Photo Credit - Wikipedia)
Mikhail Tsvet (Photo Credit - Wikipedia)

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Friday, 7 February 2020

Lycaon pictus: African Wild Dog

African wild dogs are the most highly social of the canids. They are also known as Cape hunting dogs, but this is a misnomer since their distribution includes most of Africa. Although they occur across a vast area, there are probably fewer than 7,000 individuals left. The species is classified as vulnerable by the IUCN although the IUCN / SSC canid specialist group recommends changing the listing to endangered.
African Wild dog populations have undergone a precipitous decline due to human activities. They have been adversely affected, along with most other African wildlife, by the encroachments of human habitation on wildlands. The decline of wild ungulate populations has affected them as well. Outright killing by humans is also a key factor. Wild dogs are not particularly wary of humans, and they are often shot by hunters, farmers, and Stockgrowers.

The original range of African wild dogs encompassed an area from the southern edge of the Sahara to South Africa. Sudan is the present northern limit of their distribution, which once extended into Egypt. From the eastern coastal countries of Ethiopia, Somalia, and Sudan, the range sweeps westward through Mali, Niger, and the Ivory Coast. From there it extends to the eastern border of Guinea and Burkina Faso.
African wild dogs also exist in Kenya, Tanzania, Zaire, the Congo, Zambia, Angola, Malawi, Botswana, Namibia, and South Africa. It should be remembered that although the range is huge, the population is composed of fewer than 7,000 individuals. African wild dogs have vanished from many areas where they were once common and now exist only in remote or protected areas. There, African wild dogs occur only in protected areas. When they move out of these areas they are harassed or shot.

In one area, pack sizes have declined by 99% in the period from 1980 to 1985. These reductions in pack size, an inevitable result of overall population decline, in turn, affect population levels. Smaller packs are less efficient in defending their kills from hyenas, and fewer adult helpers at dens mean lower rates of pup survival as well. In this downward spiral, decreasing population levels result in smaller pack sizes, which then result in decreased reproductive potential.
Wild dogs are found in a wide variety of habitats, including grasslands, savannas, and open woodlands. They are seldom seen in dense forests. They are found on montane savannas, and a pack was sighted on the summit of Mount Kilimanjaro at 5,895 m. Burrows, which are used only for three months each year during the breeding season, is the abandoned holes of ant bears, aardvarks, giant pangolins, or other diggers, which are appropriated and modified by the dogs.

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Wednesday, 15 January 2020

What is Myrtle Plant?

Myrtle Plant is the sacred plant of the Greek goddess Aphrodite and the Roman goddess Venus, and the messenger god Hermes fashioned his magical sandals of myrtle branches. Fragrant myrtle is associated with both love and death in the ancient world. The myrtle was originally a death-tree, on which Hippolytus in flight from Athens caught this chariot reins and was dragged to death by his horses.
A myrtle was reported to have grown near his hero's shrine. The Myrtle-nymphs were prophetesses who taught the god Aristaeus, son of Apollo and Gyrene, the useful arts of making cheese, building beehives, and cultivating olives. Venus, a very early Latin goddess of spring, seems to have been first called Murcia, a deity that later was interpreted as Myrtea, goddess of myrtles.
Sacred myrtle grew in the groves at Eleusis when the initiates to the religious mysteries trolled there, wearing the leaves as wreaths. Myrtle, along with mint and rosemary, was burned from very early times in funeral rites. Theophrastus, however, in his Characters, written in the later fourth century B.C., chides those superstitious Greeks who on the fourth and seventh days of each month buy myrtle boughs to garland their household gods.
In the first century, Pliny reports a belief that on an extended journey a foot traveler who carries a myrtle stick or rod will never feel weariness or tedium. In his Enquiry into Plants, Theophrastus tells us that of all cultivated plants myrtle and bay are least likely to thrive in cold regions. Especially myrtle, he adds, for on Mount Olympus bay is abundant, but there is no myrtle; yet in the Propontis, myrtle and bay are both found on the mountains.
In Concerning Odors he records a myrtle perfume made from the leaves and fruit of the tree. Athenians regarded the berries of the myrtle as a confection. A fragment from Anti phanes' (480-334 B.C.) comedy the Cretans begins: "But first of all/I want some myrtle berries on the table/which I may eat just as it pleases me And they must be Phibalean, very fine/Fit for a garland."
Pliny notes that even when chewed the day before, they make the mouth smell sweet and that the women eat them in Menander's comedy Synaristosae (Women at Lunch). His final word on the subject is a "prescription for offensive breath, a very embarrassing complaint.
Myrtle leaves with an equal weight of lentisci (a Syrian nut) and one-half quantity of old wine maybe chewed with benefit in the morning."In his De agriculture Cato gives instructions for making myrtle wine: dry black myrtle berries in the shade; when shriveled, store until vintage time; crush one-half peck of myrtle berries in three gallons of must; seal the vessel; when fermentation stops, remove the myrtle berries.
In the Aeneid, Virgil portrays Augustus encircling his temples with ancestress' myrtle to show his descent from the goddess Venus. He moves then to the "shores rejoicing in myrtle groves," "the myrtle in stout spear shafts," and again later to "the shore-loving myrtle."
Horace encircled his brow often, preferring simpler myrtle to the more fashionable garlands of Persian roses, as he stretched out to sip wine or to make love under the moon on his Sabine farm: "Cytherean Venus already leads her bands of dancers beneath the overhanging moon... Now is the fitting time to bind our glistening locks with green myrtle."Dioscorides calls the myrtle myrsine and distinguishes a black and a white variety.
He considers the black better medicinally and lists dozens of remedies made from it. The fruit is good for hemoptysis and ulcers, as is the juice of green myrtle which also helps the stomach. A decoction of the fruit dyes the hair black and mixed with wine it cures obstinate sores of the body extremities. Applied with flour, it relieves eye inflammations.
Pliny independently lists similar uses and adds a few others. Oil from the same myrtle is milder than the juice, and so also is myrtle wine which never intoxicates. A decoction of leaves in wine clears up freckles, hangnails, whitlows, sores of the eyelid, and venereal diseases in men.
For swelling of the groin, one need merely carries a sprig of myrtle that has touched neither iron nor the ground. Pliny also refers to a wild myrtle ("myrtus silvestris"), which can be distinguished from the cultivated by its red berries and small size, and young stalks cooked in ashes are eaten like asparagus. The plant that was eaten has been identified by modern botanists as Ruscus aculeatus, commonly known as Butcher's Broom or Jew's Myrtle.

Friday, 3 January 2020

Nutritional Profile of Rice (Wild rice)

The Nutrients in This Food

All rice is a high-carbohydrate food, rich in starch, with moderate amounts of dietary fiber. Brown rice, which has the bran (outer seed covering), is high in fiber. Rice’s proteins are plentiful but limited in the essential amino acids lysine and isoleucine.
All rice is low in fat, but brown rice, with its fatty germ (the center of the seed), has about twice as much fat as white rice. Brown rice is higher in vitamins and minerals than plain milled white rice. Enriched white rice is equivalent to plain brown rice. All rice is a source of B vitamins, including folates.
FDA ordered food manufacturers to add folates which protect against birth defects of the spinal cord and against heart disease to flour, rice, and other grain products. One year later, data from the Framingham Heart The study, which has followed heart health among residents of a Boston suburb for nearly half a century, showed a dramatic increase in blood levels of folic acid.
Before the fortification of foods, 22 percent of the study participants had a folic acid deficiency; after, the number fell to 2 percent. Rice is also a source of calcium and nonheme iron, the form of iron found in plant foods.

Most Nutritious Way to Serve This Food

With legumes (beans, peas). The proteins in rice are deficient in the essential amino acid’s lysine and isoleucine and rich in the essential amino acid’s tryptophan, methionine, and cystine. The proteins in legumes are exactly the opposite.
Combining the two foods in one dish “complements” or “completes” their proteins. With meat or a food rich in vitamin C (tomatoes, peppers). Both will increase the availability of iron in the rice.
Meat increases the secretion of stomach acids (iron is absorbed better in an acid environment); vitamin C changes the iron in the rice from ferric iron (which is hard to absorb) to ferrous iron (which is easier to absorb).

Diets That May Restrict or Exclude This Food

Low-calcium diet (brown rice, wild rice)
Low-fiber diet

How to Buy

Look for: Tightly sealed packages that protect the rice from air and moisture, which can oxidize the fats in the rice and turn them rancid. Choose the rice that meets your needs.
Long-grain rice, which has less starch than short-grain (“Oriental”) rice will be fluffier and less sticky when cooked. Brown rice has a distinctive nutty taste that can overwhelm delicate foods or “fight” with other strong flavors.
Avoid: Stained boxes of rice, even if they are still sealed. Whatever spilled on the box may have seeped through the cardboard onto the rice inside.

How to Store

Store rice in air- and moisture-proof containers in a cool, dark cabinet to keep it dry and protect its fats from oxygen. White rice may stay fresh for as long as a year.
Brown rice, which retains its bran and germ and thus has more fat than white rice, may stay fresh for only a few months before its fats (inevitably) oxidize. All rice spoils more quickly in hot, humid weather. Aging or rancid rice usually has a distinctive stale and musty odor.

How to Cook

Should you wash rice before you cook it? Yes, if you are preparing imported rice or rice purchased in bulk. No, if you are preparing prepacked white or brown rice.
You wash all varieties of bulk rice to flush away debris and/or insects. Also, wash imported rice to rinse off the cereal or corn-syrup coating.
You should pick over brown and white rice to catch the occasional pebble or stone, but washing is either worthless or detrimental. Washing brown rice has no effect one way or the other. Since the grains are protected by their bran, the water will not flush away either starches or nutrients.
Washing long-grain white rice, however, will rinse away some of the starch on the surface, which can be a plus if you want the rice to be as fluffy as possible. The downside is that washing the rice will also rinse away any nutrients remaining on plain. And milled rice and dissolve the starch/nutrient coating on enriched rice. Washing the starches off short-grain, Oriental rice will make the rice uncharacteristically dry rather than sticky.

What Happens When You Cook This Food?

Starch consists of molecules of the complex carbohydrates amylose and amylopectin packed into a starch granule. When you cook rice, the starch granules absorb water molecules. When the temperature of the water reaches approximately 140°F, the amylose and amylopectin molecules inside the starch granules relax and unfold.
Breaking some of their internal bonds (bonds between atoms on the same molecule) and forming new bonds between atoms on different molecules. The result is a starch network of starch molecules that traps and holds water molecules, making the starch granules even bulkier. In fact, rice holds so much water that it will double or even triple in bulk when cooked.
If you continue to cook the rice, the starch granules will eventually, break open, the liquid inside will leak out, the walls of the granules will collapse, and the rice will turn soft and mushy. At the same time, amylose and amylopectin molecules escaping from the granules will make the outside of the rice sticky—the reason why overcooked rice clumps together.
There are several ways to keep rice from clumping when you cook it. First, you can cook the rice in so much water that the grains have room to boil without bumping into each other, but you will lose B vitamins when you drain the excess water from the rice. Second, you can sauté the rice before you boil it or add a little fat to the boiling liquid.
Theoretically, this should make the outside of the grains slick enough to slide off each other. But this method raises the fat content of the rice with no guarantee that it will really keep the rice from clumping.
The best method is to cook the rice in just as much water as it can absorb without rupturing its starch granules. Also remove the rice from the heat as soon as the water is almost all absorbed. Fluff the cooked rice with a fork as it is cooling, to separate the grains.

How Other Kinds of Processing Affect This Food

“Converted” rice. “Converted” rice is rice that is parboiled under pressure before it is milled. This process drives the vitamins and minerals into the grain and loosens the bran so that it slips off easily when the rice is milled. Converted rice retains more vitamins and minerals than conventionally milled white rice.
“Quick-cooking” rice. This is rice that has been cooked and dehydrated. It’s hard, starchy outer covering and its starch granules have already been broken so it will reabsorb water almost instantly when you cook it.

Medical Uses and/or Benefits

To soothe irritated skin. Like corn starch or potato starch, powdered rice used as a dusting powder or stirred into the bathwater may soothe and dry a “wet” skin rash. It is so drying, however, that it should never be used on a dry skin rash or on any rash without a doctor’s advice.
As a substitute for wheat flour in a gluten-free diet. People with celiac disease have an inherited metabolic disorder which makes it impossible for them to digest gluten and gliadin, proteins found in wheat and some other grains. Rice and rice flour, which are free of gluten and gliadin, may be a useful substitute in some recipes.

Adverse Effects Associated with This Food

Beri-beri is the thiamin (vitamin B1)-deficiency disease. Beri-beri, which is rare today, occurs among people for whom milled white rice, stripped of its B vitamins, is a dietary mainstay. Enriching the rice prevents beri-beri.
Mold toxins. Rice, like other grains, may support the growth of toxic molds, including Aspergillus flavus. Which produces carcinogenic aflatoxins. Other toxins found on moldy rice include citrinin, a Penicillium mold too toxic to be used as an antibiotic; rubratoxins, mold products are known to cause hemorrhages in animals who eat the moldy rice; and nivalenol, a mold toxin that suppresses DNA and protein synthesis in cells. Because mold may turn the rice yellow, moldy rice is also known as yellow rice.

Nutritional Profile

Energy value (calories per serving): Moderate
Protein: Moderate
Fat: Low
Saturated fat: Low
Cholesterol: None
Carbohydrates: High
Fiber: Low to high
Sodium: Low
Major vitamin contribution: B vitamins
Major mineral contribution: Iron, calcium