molek

Manure gases can be Dangerous

Tue, 23 Jun 2009 21:21:29 GMT

If you are soon to empty, clean and inspect effluent pits, sumps, storage tankers or tanker-out lagoon effluent-be careful. The partial microbial breakdown of wastes during anaerobic (without oxygen) storage produces toxic gases such as ammonia, carbon dioxide and hydrogen sulphide.

These gases mostly remain dissolved while the effluent is undisturbed but are rapidly released during any pumping, agitation or mixing. The hazards are increased in pit-ends, tanks and tankers because carbon dioxide and hydrogen sulphide, being heavier than air, can concentrate to very high levels with possibly fatal results.

Hydrogen sulphide (H2S) is potentially the most lethal of the manure gases. It is colorless, has a characteristic 'rotten-egg' smell (when dilute) and is slightly heavier than air. At high concentration it is a rapid and powerful systemic poison and is instantly lethal. Above 1,000 ppm our sense of smell is paralysed so its warning odour is not detected.

A CAT Scan

Mon, 22 Jun 2009 19:19:13 GMT

A CAT scan (computer assisted tomography or computed axial tomography or computed tomography, CT) is a three-dimensional (3D) image reconstructed from a series of two-dimensional X-ray images. Compared with a conventional X-ray image, a CAT scan provides better resolution, which helps identify the position, size and shape of tumors, among other medical applications.

Cormack won the Nobel Prize in medicine in 1979 for discovering the mathematical formulas that allow scientists to reconstruct an object's cross section from a series of two-dimensional X-ray images. (Co-winner Godfrey Hounsfield constructed the first CAT scan system used in medical care.)

Other imaging methods, such as magnetic resonance imaging , frequently are used in medicine today, but computed tomography is still popular among scientists. Structural biologists use cryo-electron tomography to reconstruct 3D images of proteins from multiple 2D images taken using an electron microscope. This technique is similar to a CAT scan, except the specimen is frozen and repeatedly tilted to acquire images from different angles (in a medical CAT scan, the patient lies still, at room temperature, while the X-ray source rotates around the patient).

Researchers also use a variation of the CAT scan to examine fossils. High-resolution X-ray CT can resolve much finer details than medical CAT scans, probably because radiation exposure is not an issue with animal remains.

My favorite use of CT scanning? Rather than disassembling a vintage guitar to see how it was built, scientists used CT scans to determine how the instrument's bracing was assembled . The Gretsch model 6120 was manufactured with unique bracing from 1959-1961. Once the CT scan revealed the instrument's exact measurements, guitar makers were able to recreate the unique bracing.

Sun Clock's view of Joseph Letzelter

Fri, 19 Jun 2009 21:55:09 GMT

The Sumerian culture was lost without passing on its knowledge, but the Egyptians were apparently the next to formally divide their day into parts something like our hours. Obelisks (slender, tapering, four-sided monuments) were built as early as 3500 BCE. Their moving shadows formed a kind of sundial, enabling people to partition the day into morning and afternoon. Obelisks also showed the year's longest and shortest days when the shadow at noon was the shortest or longest of the year. Later, additional markers around the base of the monument would indicate further subdivisions of time.

Another Egyptian shadow clock or sundial, possibly the first portable timepiece, came into use around 1500 BCE. This device divided a sunlit day into 10 parts plus two "twilight hours" in the morning and evening. When the long stem with 5 variably spaced marks was oriented east and west in the morning, an elevated crossbar on the east end cast a moving shadow over the marks. At noon, the device was turned in the opposite direction to measure the afternoon "hours."

The merkhet, the oldest known astronomical tool, was an Egyptian development of around 600 BCE. A pair of merkhets was used to establish a north-south line (or meridian) by aligning them with the Pole Star. They could then be used to mark off nighttime hours by determining when certain other stars crossed the meridian.

In the quest for better year-round accuracy, sundials evolved from flat horizontal or vertical plates to more elaborate forms. One version was the hemispherical dial, a bowl-shaped depression cut into a block of stone, carrying a central vertical gnomon (pointer) and scribed with sets of hour lines for different seasons. The hemicycle, said to have been invented about 300 BCE, removed the useless half of the hemisphere to give an appearance of a half-bowl cut into the edge of a squared block. By 30 BCE, Vitruvius could describe 13 different sundial styles in use in Greece, Asia Minor, and Italy.

Clouds

Thu, 18 Jun 2009 21:28:30 GMT

Clouds form when air is cooled to its dewpoint or the temperature, if the air is cooled, it reaches saturation. Air can reach saturation in a number of ways. The most common way is through lifting.

As a bubble or parcel of air rises it moves into an area of lower pressure (pressure decreases with height). As this occurs the parcel expands. This requires energy, or work, which takes heat away from the parcel. So as air rises it cools. This is called an adiabatic process.

The rate at which the parcel cools with increasing elevation is called the "lapse rate". The lapse rate of unsaturated air (air with relative humidity <100%) is 5.4�F per 1000 feet (9.8�C per kilometer). This is called the dry lapse rate. This means for each 1000 feet increase in elevation, the air temperature will decrease 5.4�F.

Since cold air can hold less water vapor than warm air, some of the vapor will condense onto tiny clay and salt particles called condensation nuclei. The reverse is also true. As a parcel of air sinks it encounters increasing pressure so it is squeezed inward.

This adds heat to the parcel so it warms as it sinks. Warm air can hold more water vapor than cold air, so clouds tend to evaporate as air sinks.

Coast Defense Works at Zhenhaikou

Wed, 17 Jun 2009 20:20:10 GMT

Situated on the coast of the East China Sea, Zhenhai has been known from ancient times as "Hai Tian Xiong Zhen"--"grand town facing the sea" and "Zhe Dong Men Hu"--"gateway of east Zhejiang Province". It is here the Yongjiang River, which receives the Yuyao River and Fenghua River at Sanjiangkou in the downtown of Ningbo City, flows eastward into the sea. Right at the mouth of the Yongjiang River on its north and south banks stand Zhaobao Hill and Golden Rooster Hill, which are like a gate that guards the town against the water of the East China Sea. Thus it has its name "Zhenhaikou". For its position, Zhenhaikou has been an important strategic point for coast defense.

Zhenhaikou used to be a battlefield where today remain numerous coast defense works which witnessed the heroic and soul-stirring struggles of the Chinese army and the people from the southeast coastal areas in their resistance of the pirates and invaders from Japan, England and France. It is here in the Ming Dynasty (1368-1644), many famous generals, such as Lu Tong, Yu Dayou, Qi Jiguang, led their armies to fight fierce battles against Japanese invaders and made brilliant military victories. During the First Opium War (1840-1842), Lin Zexu, a national hero, came to Zhenhai to supervise the building of the defense work and cannons, war chariots and boats, which crowned him with eternal glory. Yu Qian, the Imperial Commissioner and Governor-general of Jiangsu and Zhejiang, led his army to fight fiercely against British invaders and died heroically. During the Sino-French War (1884-1885), the soldiers and people of Zhenhai, led by generals Liu Bingzhang, Ouyang Lijian, Xue Fucheng, Yang Qizhen, Du Guanying and Wu Jie, defeated the French fleet--the only complete victory that the Chinese people made in coastal battles in the history of Chinese anti-aggression wars in modern times. During the War of Resistance against Japan, the soldiers and the people of Zhenhai, together with guerrillas, defeated the Japanese invasions many times and on July 17, 1940 alone, they killed and wounded more than 400 Japanese invaders.

The sites of coast defense works are scattered on both banks of the Yongjiang River and they form 4 groups of scenes around Ziyin Hill, Jinzi Hill, Zhaobao Hill and Golden Rooster Hill. These sites include military headquarters, looking-out towers, defense walls, campsites, forts, pillboxes, trenches and sentry boxes for alarming, etc. All these relics are well preserved. In order to carry forward the national spirit and help people keep firmly in mind the lesson taught by history that a backward country is bullied by others, the government of Zhenhai District made a decision in 1994 to protect and develop the sites and carry out a project for patriotism education. This decision was enthusiastically echoed by people of various circles and overseas Chinese and they donated more than 10 million yuan for the project. The Central Committee of the Communist Youth League named the sites "National Socialist Education Base for the Youth".

Life and habitat of Kangaroos

Tue, 16 Jun 2009 18:30:35 GMT

Kangaroos are herbivorous, eating a range of plants and, in some cases, fungi. Most are nocturnal but some are active in the early morning and late afternoon. Different kangaroo species live in a variety of habitats. Potoroids, for example, make nests while tree-kangaroos live above ground in trees. Larger species of kangaroo tend to shelter under trees or in caves and rock clefts.

Kangaroos of all sizes have one thing in common: powerful back legs with long feet. Most kangaroos live on the ground and are distinguished from other animals by the way they hop on their strong back legs. A kangaroo�s tail is used to balance while hopping and as a fifth limb when moving slowly.

All female kangaroos have front-opening pouches that contain four teats. This is where the �joey�, or young kangaroo, is raised until it can survive outside the pouch.

Most kangaroos have no set breeding cycle and are able to breed all year round. Because they are such prolific breeders, a kangaroo population can increase fourfold in five years if it has continuous access to plentiful food and water.

Cocaine Smuggling Vessel Becomes Diver�s Paradise

Mon, 15 Jun 2009 20:34:56 GMT

The M/V Lourdies, a vessel seized by U.S. Customs and Border Protection officers nearly a year ago after it was used in an attempt to smuggle 389 pounds of cocaine on the Miami River, was scuttled and converted into an artificial reef on Saturday, June 6.

The event took take place about one mile from shore just north of the pier at Deerfield Beach, Fla. It was 20 days short of one year ago that, while conducting an in depth search of the vessel CBP officers discovered a void space behind one of the unoccupied crew quarters wood paneling.

Upon removing the paneling a metal box was found welded to the bulk head. Inside the metal box were 154 kilo-sized bricks, which field tested positive for cocaine. The cocaine had an estimated street value of $12 million.

A collaboration of federal, state, and local agencies working alongside private stakeholders were able to successfully navigate the complex set of legal rules and regulations required to complete this project. It was a daunting task that covered everything from deciding on a location and properly preparing the vessel to insuring that all environmental and historical concerns were addressed.

The vessel was renamed �The Miracle of Life� and now sits in about 140 feet of water awaiting the many recreational divers who will visit her in the years to come.

�This event was the result of an outstanding interception and seizure by CBP. It also demonstrates what we are capable of accomplishing when we work together with our partners towards a common goal,� said Director of Field Operations Harold Woodward.

Galileo's Views of the Moon

Fri, 12 Jun 2009 22:01:00 GMT

The first telescopic drawings of the Moon were made and published by Italian astronomer and physicist Galileo Galilei (1564-1642) in 1610. Because he showed the Moon to be a solid body with irregular surface features, he would later argue that the Earth was not unique. Using simple geometry, he used the shadows cast by the lunar mountains to calculate correctly their height. This led to his disagreement with Aristotle's theory of an immutable universe and to his controversial defense of the Copernican system in 1632.

Early history of Martial Arts

Thu, 11 Jun 2009 19:07:58 GMT

The earliest evidence for specifics of martial arts as practiced in the past comes from depictions of fights, both in figurative art and in early literature, besides analysis of archaeological evidence, especially of weaponry.

Wrestling is a human universal, and is also observed in other great apes, especially in juveniles. The spear has been in use since the Lower Paleolithic and retained its central importance well into the 2nd millennium AD. The bow appears in the Upper Paleolithic and is likewise only gradually replaced by the crossbow, and eventually firearms, in the Common Era. True bladed weapons appear in the Neolithic with the stone axe, and diversify in shape in the course of the Bronze Age.

One very early example is the depiction of wrestling techniques in a tomb of the Middle Kingdom of Egypt at Beni Hasan (ca. 2000 BC). An even earlier depiction of Bronze Age military equipment is depicted on the "war panel" of the Standard of Ur (ca. 2600 BC), which does however not show actual combat.

Literary descriptions of combat begin in the 2nd millennium BC, with cursory mention of weaponry and combat in texts like the Gilgamesh epic or the Rigveda. Detailed description of Late Bronze Age to Early Iron Age hand-to-hand combat with spear, sword and shield are found in the Iliad (ca. 8th century BC). Pictorial representations of fist fighting in Minoan civilization date to the 2nd millennium BC.

Rainbow Features

Wed, 20 May 2009 22:18:42 GMT

Rainbows are awesome. Have you ever looked at them right after it rains, or through the water outside? Well, I have and I think that they are interesting.

A rainbow is an arch of light showing the colors of the light spectrum. The colors are seen in order with red on the outside, followed by orange, yellow, green, blue, indigo, and violet.

Rainbows are caused by drops of water that are falling through the air. They are usually seen in the sky opposite to the sun at the end of a shower. They can also be seen in the spray of waterfalls.

When the sunlight enters a raindrop it is bent by and reflected from the drop. When this happens the light appears as a spectrum of colors. But, the colors can only be seen when the angle of reflection between the sun, the water drop, and the observer's line of version is between 40 degrees and 42 degrees.

The rainbow appears high when the sun is low in the sky, the rainbow is lower, when the sun is higher. When the sun is up higher than 42 degrees above the horizon, a rainbow cannot be seen because the required angle passes over the head of the observer.