Human reproduction takes place as internal fertilization by sexual intercourse. During this process, the erect penis of the male is inserted into the female's vagina until the male ejaculates semen, which contains sperm, into the female's vagina. The sperm then travels through the vagina and cervix into the uterus or fallopian tubes for fertilization of the ovum.
Pelvic region of a male that contribute towards the reproductive process. The primary direct function of the male reproductive system is to provide the male gamete or spermatozoa for fertilization of the ovum.
The major reproductive organs of the male can be grouped into three categories. The first category is sperm production and storage. Production takes place in the testes which are housed in the temperature regulating scrotum, immature sperm then travel to the epididymis for development and storage. The second category is the ejaculatory fluid producing glands which include the seminal vesicles, prostate, and the vas deferens. The final category are those used for copulation, and deposition of the spermatozoa (sperm) within the female, these include the penis, urethra, vas deferens and Cowper's gland.
Pelvic region of a female that contribute towards the reproductive process. The human female reproductive system contains three main parts: the vagina, which acts as the receptacle for the male's sperm, the uterus, which holds the developing fetus, and the ovaries, which produce the female's ova. The breasts are also an important reproductive organ during the parenting stage of reproduction.
The vagina meets the outside at the vulva, which also includes the labia, clitoris and urethra; during intercourse this area is lubricated by mucus secreted by the Bartholin's glands. The vagina is attached to the uterus through the cervix, while the uterus is attached to the ovaries via the fallopian tubes. At certain intervals, typically approximately every 28 days, the ovaries release an ovum, which passes through the fallopian tube into the uterus. The lining of the uterus, called the endometrium, and unfertilized ova are shed each cycle through a process known as menstruation.
sábado, 31 de enero de 2009
HISTORY OF THE WORLD'S LARGEST BUILDING.
BEFORE THE 19TH CENTURY.
Modern skyscrapers are built with materials such as steel, glass, reinforced concrete and granite, and routinely utilize mechanical equipment such as water pumps and elevators. Until the 19th century, buildings of over six stories were rare, as having great numbers of stairs to climb was impractical for inhabitants, and water pressure was usually insufficient to supply running water above 50 m (164 ft).
The tallest building in ancient times was the Great Pyramid of Giza in ancient Egypt, which was 146 metres (480 ft) tall and was built in the 26th century BC. Its height was not surpassed for thousands of years, possibly until the 14th century AD with the construction of the Lincoln Cathedral (though its height is disputed), which in turn was not surpassed in height until the Washington Monument in 1884. However, being uninhabited buildings, none of these buildings actually complies to the definition of a skyscraper.
High-rise apartment building already flourished in antiquity: ancient Roman insulae in Rome and other imperial cities reached up to 10 and more stories, some with more than 200 stairs. Several emperors, beginning with Augustus (r. 30 BC-14 AD), attempted to establish limits of 20-25 m for multi-story buildings, but met with only limited success. The lower floors were typically occupied by either shops or wealthy families, while the upper stories were rented out to the lower classes. Surviving Oxyrhynchus Papyri indicate that seven story buildings even existed in provincial towns, such as in 3rd century AD Hermopolis in Roman Egypt.
The skyline of many important medieval cities had large numbers of high-rise urban towers. These towers were built for defensive but also representative functions by the wealthiest families. The residential Towers of Bologna in the 12th century, for example, numbered between 80 to 100 at a time, the largest of which (known as the "Two Towers") rise to 97.2 metres (319 ft). In Florence, a law of 1251 decreed that all urban buildings should be reduced to a height of less than 26 m, the regulation immediately put into effect. Even medium-sized towns at the time such as San Gimignano are known to have featured 72 towers up to 51 m height.
The medieval Egyptian city of Fustat housed many high-rise residential buildings, which Al-Muqaddasi in the 10th century described as resembling minarets. Nasir Khusraw in the early 11th century described some of them rising up to 14 stories, with roof gardens on the top storey complete with ox-drawn water wheels for irrigating them. Cairo in the 16th century had high-rise apartment buildings where the two lower floors were for commercial and storage purposes and the multiple stories above them were rented out to tenants. An early example of a city consisting entirely of high-rise housing is the 16th-century city of Shibam in Yemen. Shibam was made up of over 500 tower houses, each one rising 5 to 11 storeys high, with each floor being an apartment occupied by a single family. The city was built in this way in order to protect it from Bedouin attacks. Shibam still has the tallest mudbrick buildings in the world, with many of them over 100 feet (30 m) high, and the tallest of them (a minaret) standing at over 175 feet (53 m).
Modern skyscrapers are built with materials such as steel, glass, reinforced concrete and granite, and routinely utilize mechanical equipment such as water pumps and elevators. Until the 19th century, buildings of over six stories were rare, as having great numbers of stairs to climb was impractical for inhabitants, and water pressure was usually insufficient to supply running water above 50 m (164 ft).
The tallest building in ancient times was the Great Pyramid of Giza in ancient Egypt, which was 146 metres (480 ft) tall and was built in the 26th century BC. Its height was not surpassed for thousands of years, possibly until the 14th century AD with the construction of the Lincoln Cathedral (though its height is disputed), which in turn was not surpassed in height until the Washington Monument in 1884. However, being uninhabited buildings, none of these buildings actually complies to the definition of a skyscraper.
High-rise apartment building already flourished in antiquity: ancient Roman insulae in Rome and other imperial cities reached up to 10 and more stories, some with more than 200 stairs. Several emperors, beginning with Augustus (r. 30 BC-14 AD), attempted to establish limits of 20-25 m for multi-story buildings, but met with only limited success. The lower floors were typically occupied by either shops or wealthy families, while the upper stories were rented out to the lower classes. Surviving Oxyrhynchus Papyri indicate that seven story buildings even existed in provincial towns, such as in 3rd century AD Hermopolis in Roman Egypt.
The skyline of many important medieval cities had large numbers of high-rise urban towers. These towers were built for defensive but also representative functions by the wealthiest families. The residential Towers of Bologna in the 12th century, for example, numbered between 80 to 100 at a time, the largest of which (known as the "Two Towers") rise to 97.2 metres (319 ft). In Florence, a law of 1251 decreed that all urban buildings should be reduced to a height of less than 26 m, the regulation immediately put into effect. Even medium-sized towns at the time such as San Gimignano are known to have featured 72 towers up to 51 m height.
The medieval Egyptian city of Fustat housed many high-rise residential buildings, which Al-Muqaddasi in the 10th century described as resembling minarets. Nasir Khusraw in the early 11th century described some of them rising up to 14 stories, with roof gardens on the top storey complete with ox-drawn water wheels for irrigating them. Cairo in the 16th century had high-rise apartment buildings where the two lower floors were for commercial and storage purposes and the multiple stories above them were rented out to tenants. An early example of a city consisting entirely of high-rise housing is the 16th-century city of Shibam in Yemen. Shibam was made up of over 500 tower houses, each one rising 5 to 11 storeys high, with each floor being an apartment occupied by a single family. The city was built in this way in order to protect it from Bedouin attacks. Shibam still has the tallest mudbrick buildings in the world, with many of them over 100 feet (30 m) high, and the tallest of them (a minaret) standing at over 175 feet (53 m).
SHANGHAI SKYSCRAPER NAMED “BEST TALL BUILDING”
The Council on Tall Buildings and the Urban Habitat has named the Shanghai World Financial Center the “Best Tall Building Overall” for 2008. Designed by Kohn Pedersen Fox (KPF) and completed last year, the building was chosen from among four “Regional Tall Building” winners, including The New York Times Building by Renzo Piano Building Workshop with FXFOWLE, London’s 51 Lime Street by Foster and Partners, and the Bahrain World Trade Center by Atkins.
The Shanghai World Financial Center, which boasts the highest occupied floor in the world, was chosen as the winner for “its revolutionary structural design and inspirational symbolism,” according to the council. Formed out of a square prism intersected by two “cosmic arcs,” the building includes a distinctive, multi-story trapezoidal aperture at its upper floors. The firm’s design was inspired by two Chinese burial symbols: “a square prism essentially representative of the earth, and a heaven symbol—a circular disc with a circular aperture cut through it,” says Bill Pedersen, FAIA, of KPF. “We wanted to do a building that was a genuine expression of the relationship between the earth and the sky,” he explains, “and also that could be connected to the culture within which it is placed.”
The tower’s tapering form is more than an aesthetic move—it also allows the building to maximize floor plate and material efficiency. Structural innovations by the engineering firm Leslie E. Robertson Associates succeeded in increasing the building’s volume by 20 percent while retaining its original weight, thereby minimizing its total embodied energy. And the range of floor plates that the design’s unique geometry creates allowed KPF to “negotiate the different program necessities” of the building’s office, hotel, and retail components, according to Pedersen.
Though the building is replete with unusual features, Pedersen singles out one as particularly important: the tower houses a seven-story observatory and two sky walks on the 97th and 100th floors, thereby opening its most spectacular spaces and best views to the public. “One of the things we’re most proud of in this building,” says Pedersen, “is that the top 80 meters are devoted to functions that everyone can go in and enjoy.”
The Shanghai World Financial Center, which boasts the highest occupied floor in the world, was chosen as the winner for “its revolutionary structural design and inspirational symbolism,” according to the council. Formed out of a square prism intersected by two “cosmic arcs,” the building includes a distinctive, multi-story trapezoidal aperture at its upper floors. The firm’s design was inspired by two Chinese burial symbols: “a square prism essentially representative of the earth, and a heaven symbol—a circular disc with a circular aperture cut through it,” says Bill Pedersen, FAIA, of KPF. “We wanted to do a building that was a genuine expression of the relationship between the earth and the sky,” he explains, “and also that could be connected to the culture within which it is placed.”
The tower’s tapering form is more than an aesthetic move—it also allows the building to maximize floor plate and material efficiency. Structural innovations by the engineering firm Leslie E. Robertson Associates succeeded in increasing the building’s volume by 20 percent while retaining its original weight, thereby minimizing its total embodied energy. And the range of floor plates that the design’s unique geometry creates allowed KPF to “negotiate the different program necessities” of the building’s office, hotel, and retail components, according to Pedersen.
Though the building is replete with unusual features, Pedersen singles out one as particularly important: the tower houses a seven-story observatory and two sky walks on the 97th and 100th floors, thereby opening its most spectacular spaces and best views to the public. “One of the things we’re most proud of in this building,” says Pedersen, “is that the top 80 meters are devoted to functions that everyone can go in and enjoy.”
domingo, 11 de enero de 2009
MODERN ELECTRONICS.
It can be stated that new materials lead to new developments in technology. In modern electronics, for example, semiconductors have le to many advances such as transistors, Diodes and integrated circuits. These devices have made possible the manufacture of revolutionary equipment. Such as portable TV sets and central 5 processing units (CPUs).
Three good examples of semiconductor materials are silicon, germanium and gallium arsenide. Silicon is the most widely used semiconductor and it is basically used for integrated circuits. Germanium is primarily used for transistors and diodes. Gallium arsenide is a very fast semiconductor and it is mainly used in applications where fast speed is essential. For instance, in computers and high-frequency applications.
Among the conductors, copper has been widely used for cables but lately it is being replaced by optical fibers, that is, thin and flexible fibers made of glass. Insulating materials, such as glass. Rubber, paper, air or ceramics and plastics are widely used for insulation and mounting parts.
Other important materials in electronics are iron. Nickel and cobalt. These are ferromagnetic materials and they are extensively used as alloys and oxides in recording media like tapes and discs.
Three good examples of semiconductor materials are silicon, germanium and gallium arsenide. Silicon is the most widely used semiconductor and it is basically used for integrated circuits. Germanium is primarily used for transistors and diodes. Gallium arsenide is a very fast semiconductor and it is mainly used in applications where fast speed is essential. For instance, in computers and high-frequency applications.
Among the conductors, copper has been widely used for cables but lately it is being replaced by optical fibers, that is, thin and flexible fibers made of glass. Insulating materials, such as glass. Rubber, paper, air or ceramics and plastics are widely used for insulation and mounting parts.
Other important materials in electronics are iron. Nickel and cobalt. These are ferromagnetic materials and they are extensively used as alloys and oxides in recording media like tapes and discs.
WHAT’S IN THE NEWS KICKING COFFEE HABIT PRODUCES A DROP IN BLOOD PRESSURE
Healthy men who drank three to six cups of coffee a day experienced a significant drop in blood pressure when they kicked the habit, researchers said.
The researchers think the drop might be larger in people with high blood pressure, who should be advised to give up coffee, said one of the study’s authors, Dr. Robert Superko of Stanford University.
“Maybe this will help them prevent drug treatment” for high blood pressure, said the study’s principal author, Jeff Myll of Stanford. “It’s worth a try”.
The findings were presented at the annual meeting of the American Collage of Cardiology.
The new study was done with 120 healthy men with a median age of 45. They were given three to six cups of coffee a day for eight weeks, and then half of them were taken off coffee.
When researchers compared the coffee drinkers with the non-coffee drinker, they found a difference of 5 points in systolic blood pressure-when the heart is pumping- and a difference of about 3 points in diastolic pressure.
- When the heart is relaxed between beats.
Blood pressure was measured with a device that patients wore, so readings could be recorded every half hour throughout the day, the researchers said.
This provides a more accurate assessment of the effect of coffee on blood pressure, they said. No difference in blood pressure was found when patients were measured in the conventional manner.
“Coffee is complex fluid”. “There’s a lot of things that’s going on. It’s not just caffeine”, said Dr. Myll, one of the researchers.
The relationship between decaffeinated coffee and cholesterol “has to do with the chemical differences in the types of beans they use” for decaffeinated coffee.
The Daily. Anniversary Supplement. Caracas.
The researchers think the drop might be larger in people with high blood pressure, who should be advised to give up coffee, said one of the study’s authors, Dr. Robert Superko of Stanford University.
“Maybe this will help them prevent drug treatment” for high blood pressure, said the study’s principal author, Jeff Myll of Stanford. “It’s worth a try”.
The findings were presented at the annual meeting of the American Collage of Cardiology.
The new study was done with 120 healthy men with a median age of 45. They were given three to six cups of coffee a day for eight weeks, and then half of them were taken off coffee.
When researchers compared the coffee drinkers with the non-coffee drinker, they found a difference of 5 points in systolic blood pressure-when the heart is pumping- and a difference of about 3 points in diastolic pressure.
- When the heart is relaxed between beats.
Blood pressure was measured with a device that patients wore, so readings could be recorded every half hour throughout the day, the researchers said.
This provides a more accurate assessment of the effect of coffee on blood pressure, they said. No difference in blood pressure was found when patients were measured in the conventional manner.
“Coffee is complex fluid”. “There’s a lot of things that’s going on. It’s not just caffeine”, said Dr. Myll, one of the researchers.
The relationship between decaffeinated coffee and cholesterol “has to do with the chemical differences in the types of beans they use” for decaffeinated coffee.
The Daily. Anniversary Supplement. Caracas.
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