Sauropods were a group of dinosaurs that were all built to the same general design. They all had a short barrel-shaped body to accommodate the huge gut needed to digest their vegetable diet, a very long neck and tail, a comparatively tiny head and peg-like teeth for grazing. The other important feature of the sauropods is that they were all enormous. They were extremely heavy, and because they lived in large herds they churned up the ground as they move about. It is still possible to see the damage caused by their movements in the ancient rock layers were fossils of the sauropods were found.
The long neck of the sauropods is thought to be an adaptation to help animals feed on tall trees, like the modern giraffe. The whole structure of the dinosaurs is a very clever piece of engineering, because their long neck, which was usually held out horizontally, was balanced by the weight of the tail. The vertebrae were shaped to allow the attachment of powerful muscles and rope-like tendons and ligaments, which held the whole structure together like a suspension bridge. Despite the great length of the neck and tail, they were not a flexible as we might think. They were usually stretched out almost in a straight line.
Sunday, March 18, 2007
Thursday, March 15, 2007
Is sex necessary?
Is sex really necessary in our everyday life? What are the health benefits of sex?
Improved sense of smell
After sex, production of the hormone prolactin surges. This in turn causes stem cells in the brain to develop new neurons in the brain's olfactory bulb, its smell center.
Reduced risk of heart disease
In a 2001 follow-up to the Queens University study mentioned above, researchers focused on cardiovascular health. Their finding? That by having sex three or more times a week, men reduced their risk of heart attack or stroke by half. In reporting these results, the co-author of the study, Shah Ebrahim, Ph.D., displayed the well-loved British gift for understatement: "The relationship found between frequency of sexual intercourse and mortality is of considerable public interest."
Weight loss, overall fitness
Sex, if nothing else, is exercise. A vigorous bout burns some 200 calories--about the same as running 15 minutes on a treadmill or playing a spirited game of squash. The pulse rate, in a person aroused, rises from about 70 beats per minute to 150, the same as that of an athlete putting forth maximum effort. British researchers have determined that the equivalent of six Big Macs can be worked off by having sex three times a week for a year. Muscular contractions during intercourse work the pelvis, thighs, buttocks, arms, neck and thorax. Sex also boosts production of testosterone, which leads to stronger bones and muscles. Men's Health magazine has gone so far as to call the bed the single greatest piece of exercise equipment ever invented.
Reduced depression
Such was the implication of a 2002 study of 293 women. American psychologist Gordon Gallup reported that sexually active participants whose male partners did not use condoms were less subject to depression than those whose partners did. One theory of causality: Prostoglandin, a hormone found only in semen, may be absorbed in the female genital tract, thus modulating female hormones.
Pain relief
Immediately before orgasm, levels of the hormone oxytocin surge to five times their normal level. This in turn releases endorphins, which alleviate the pain of everything from headache to arthritis to even migraines. In women, sex also prompts production of estrogen, which can reduce the pain of PMS.
Less-frequent colds and flu
Wilkes University in Pennsylvania says individuals who have sex once or twice a week show 30% higher levels of an antibody called immunoglobulin A, which is known to boost the immune system.
Better bladder control
Ever hear of Kegel exercises? You do them, whether you know it or not, every time you stem your flow of urine. The same set of muscles is worked during sex.
Better teeth
Seminal plasma contains zinc, calcium and other minerals shown to retard tooth decay. Since this is a family Web site, we will omit discussion of the mineral delivery system. Suffice it to say that it could be a far richer, more complex and more satisfying experience than squeezing a tube of Crest--even Tartar Control Crest. Researchers have noted, parenthetically, that sexual etiquette usually demands the brushing of one's teeth before and/or after intimacy, which, by itself, would help promote better oral hygiene.
A happier prostate?
Some urologists believe they see a relationship between infrequency of ejaculation and cancer of the prostate. The causal argument goes like this: To produce seminal fluid, the prostate and the seminal vesicles take such substances from the blood as zinc, citric acid and potassium, then concentrate them up to 600 times. Any carcinogens present in the blood likewise would be concentrated. Rather than have concentrated carcinogens hanging around causing trouble, it's better to evict them. Regular old sex could do the job. But if the flushing of the prostate were your only objective, masturbation might be a better way to go, especially for the nonmonogamous male. Having sex with multiple partners can, all by itself, raise a man's risk of cancer by up to 40%. That's because he runs an increased risk of contracting sexual infections. So, if you want all the purported benefits of flushing with none of the attendant risk, go digital. A study recently published by the British Journal of Urology International asserts that men in their 20s can reduce by a third their chance of getting prostate cancer by ejaculating more than five times a week.
Improved sense of smell
After sex, production of the hormone prolactin surges. This in turn causes stem cells in the brain to develop new neurons in the brain's olfactory bulb, its smell center.
Reduced risk of heart disease
In a 2001 follow-up to the Queens University study mentioned above, researchers focused on cardiovascular health. Their finding? That by having sex three or more times a week, men reduced their risk of heart attack or stroke by half. In reporting these results, the co-author of the study, Shah Ebrahim, Ph.D., displayed the well-loved British gift for understatement: "The relationship found between frequency of sexual intercourse and mortality is of considerable public interest."
Weight loss, overall fitness
Sex, if nothing else, is exercise. A vigorous bout burns some 200 calories--about the same as running 15 minutes on a treadmill or playing a spirited game of squash. The pulse rate, in a person aroused, rises from about 70 beats per minute to 150, the same as that of an athlete putting forth maximum effort. British researchers have determined that the equivalent of six Big Macs can be worked off by having sex three times a week for a year. Muscular contractions during intercourse work the pelvis, thighs, buttocks, arms, neck and thorax. Sex also boosts production of testosterone, which leads to stronger bones and muscles. Men's Health magazine has gone so far as to call the bed the single greatest piece of exercise equipment ever invented.
Reduced depression
Such was the implication of a 2002 study of 293 women. American psychologist Gordon Gallup reported that sexually active participants whose male partners did not use condoms were less subject to depression than those whose partners did. One theory of causality: Prostoglandin, a hormone found only in semen, may be absorbed in the female genital tract, thus modulating female hormones.
Pain relief
Immediately before orgasm, levels of the hormone oxytocin surge to five times their normal level. This in turn releases endorphins, which alleviate the pain of everything from headache to arthritis to even migraines. In women, sex also prompts production of estrogen, which can reduce the pain of PMS.
Less-frequent colds and flu
Wilkes University in Pennsylvania says individuals who have sex once or twice a week show 30% higher levels of an antibody called immunoglobulin A, which is known to boost the immune system.
Better bladder control
Ever hear of Kegel exercises? You do them, whether you know it or not, every time you stem your flow of urine. The same set of muscles is worked during sex.
Better teeth
Seminal plasma contains zinc, calcium and other minerals shown to retard tooth decay. Since this is a family Web site, we will omit discussion of the mineral delivery system. Suffice it to say that it could be a far richer, more complex and more satisfying experience than squeezing a tube of Crest--even Tartar Control Crest. Researchers have noted, parenthetically, that sexual etiquette usually demands the brushing of one's teeth before and/or after intimacy, which, by itself, would help promote better oral hygiene.
A happier prostate?
Some urologists believe they see a relationship between infrequency of ejaculation and cancer of the prostate. The causal argument goes like this: To produce seminal fluid, the prostate and the seminal vesicles take such substances from the blood as zinc, citric acid and potassium, then concentrate them up to 600 times. Any carcinogens present in the blood likewise would be concentrated. Rather than have concentrated carcinogens hanging around causing trouble, it's better to evict them. Regular old sex could do the job. But if the flushing of the prostate were your only objective, masturbation might be a better way to go, especially for the nonmonogamous male. Having sex with multiple partners can, all by itself, raise a man's risk of cancer by up to 40%. That's because he runs an increased risk of contracting sexual infections. So, if you want all the purported benefits of flushing with none of the attendant risk, go digital. A study recently published by the British Journal of Urology International asserts that men in their 20s can reduce by a third their chance of getting prostate cancer by ejaculating more than five times a week.
What are tectonic plates?
The Earth's crust is made up of about 30 huge plates that float on the semi-liquid mantle surrounding the earth's core. There are currents and movements in the mantle, so these plates move very slowly in relation to each other - about 10 cm per year on average. The floor of the Pacific Ocean is one enormous plate. Some of the plates carrying continents also carry parts of the ocean floor. The thickness of the plates varies from 8 km to 200 km.
Earthquakes are evidence of movement of the tectonic plates that carry the continents. Most of the areas where earthquakes take place are along the edges of the plates. Friction holds the plate edges together for a while, but continuing movement means that huge stresses built up. The tension is suddenly released when the plates shift sharply and this causes earthquakes. There are other causes of earthquakes, but they all involve sudden movement of the crust along a fault or crack. The energy released in an earthquake is enormous - as much as 10,000 times the power released by the world's first atomic bomb.
Earthquakes are evidence of movement of the tectonic plates that carry the continents. Most of the areas where earthquakes take place are along the edges of the plates. Friction holds the plate edges together for a while, but continuing movement means that huge stresses built up. The tension is suddenly released when the plates shift sharply and this causes earthquakes. There are other causes of earthquakes, but they all involve sudden movement of the crust along a fault or crack. The energy released in an earthquake is enormous - as much as 10,000 times the power released by the world's first atomic bomb.
Wednesday, March 14, 2007
What are explosives?
Explosives are substances that release a very large amount of energy in a short time when they burn. They all contain a fuel plus an oxidizer, which is a substance containing sufficient oxygen to burn the fuel. Explosives do not need air to explode, because they contain their own oxygen, and so they can burn in confined spaces or even underwater. Some explosives, such as those in a cartridge detonator, explode violently when hit or heated. Others only cause a violent explosion when confined in a gun barrel or a hole drilled in rock for blasting.
Gunpowder, the first ever explosive, was invented in China over 1,000 years ago. Large amounts of modern explosives are commonly used in quarrying and mining, as well as for munitions.
Gunpowder, the first ever explosive, was invented in China over 1,000 years ago. Large amounts of modern explosives are commonly used in quarrying and mining, as well as for munitions.
What is health?
Being healthy involves far more than simply not being ill. If you feel you're in good health, your organs will be working properly and you will have the energy to live life to the full. This feeling of wellbeing affects your mind and your body.
The environment you live in, your diet and your lifestyles affect your health. Physical fitness is an important part of health, and this means that your heart, lungs, skeleton and muscles all work together smoothly to carry out your daily activities. Fitness involves strength, stamina and suppleness, and you need regular exercise to maintain all these conditions. Careful exercise develops a healthy heart and lungs, and gives you the strength and stamina that allow you to run, cycle and swim. A sensible diet and sufficient sleep also help you to keep healthy.
Air pollution is an environmental factor that can damage health. Exhaust fumes from motor vehicles contain substances that can cause asthma and other breathing problems. In hot climates, smog can also develop, trapping these air pollutants and making the health risk greater.
Many diseases are infections that are caused by bacteria or virus. Other illnesses are caused by failure of some of the body's organs or tissues. Sometimes part of the body wear out or are not replaced properly, but most health problems are caused when the body simply fails to maintain itself. Joints can wear out, causing arthritis, or the digestive system may not work as efficiently, causing various types of stomach upsets. Other diseases may be caused by a person's own lifestyle, for example lack of exercise or poor eating habits. Smoking is now known to be a contributory factor in many diseases.
The environment you live in, your diet and your lifestyles affect your health. Physical fitness is an important part of health, and this means that your heart, lungs, skeleton and muscles all work together smoothly to carry out your daily activities. Fitness involves strength, stamina and suppleness, and you need regular exercise to maintain all these conditions. Careful exercise develops a healthy heart and lungs, and gives you the strength and stamina that allow you to run, cycle and swim. A sensible diet and sufficient sleep also help you to keep healthy.
Air pollution is an environmental factor that can damage health. Exhaust fumes from motor vehicles contain substances that can cause asthma and other breathing problems. In hot climates, smog can also develop, trapping these air pollutants and making the health risk greater.
Many diseases are infections that are caused by bacteria or virus. Other illnesses are caused by failure of some of the body's organs or tissues. Sometimes part of the body wear out or are not replaced properly, but most health problems are caused when the body simply fails to maintain itself. Joints can wear out, causing arthritis, or the digestive system may not work as efficiently, causing various types of stomach upsets. Other diseases may be caused by a person's own lifestyle, for example lack of exercise or poor eating habits. Smoking is now known to be a contributory factor in many diseases.
Monday, March 12, 2007
What are Hormones?
Hormones are chemical messengers that are produced in one part of the body and have an effect on another part.
Hormones switch body processes on and off, and they regulate most of the body's activity. The nervous system also helps in these processes, giving pared instructions along the nerves. The body's endocrine system uses hormones which work much more slowly. The majority of hormones are carried around the body in the bloodstream, reaching all the major organs and tissues.
The body has more than 30 different hormones. They are mostly produced in organs called endocrine glands.
These glands discharge the hormones directly into the bloodstream. Other types of glands pass their secretions through ducts to the point where they are needed. Endocrine glands are found in the head, neck and torso. The amount of hormones in the body is regulated by a feedback system. This means that once hormones are produced, the body measures them and once they have reached the required level, their production is switched off again. Sometimes this mechanism does not work properly and over or underactive glands such as the thyroid can produce illness.
Hormones switch body processes on and off, and they regulate most of the body's activity. The nervous system also helps in these processes, giving pared instructions along the nerves. The body's endocrine system uses hormones which work much more slowly. The majority of hormones are carried around the body in the bloodstream, reaching all the major organs and tissues.
The body has more than 30 different hormones. They are mostly produced in organs called endocrine glands.
These glands discharge the hormones directly into the bloodstream. Other types of glands pass their secretions through ducts to the point where they are needed. Endocrine glands are found in the head, neck and torso. The amount of hormones in the body is regulated by a feedback system. This means that once hormones are produced, the body measures them and once they have reached the required level, their production is switched off again. Sometimes this mechanism does not work properly and over or underactive glands such as the thyroid can produce illness.
Sunday, March 11, 2007
What is electricity?
Electricity powers our lights, heating, electronic appliances such as computers and television, and a host of other essential services that we take for granted. However, electricity has much more important aspects because it is the force that holds together the molecules and atoms of all substances.
The type of electricity that is most familiar to us is electrical current. This is the flow of electrical charges through a substance called a conductor, such as a metal wire. This flow happens because some of the negatively charged electrons circling the nuclei of the conductor's atoms are held loosely. The electrons can move from one atom to the next, producing an electrical current.
Energy can no be created. An electrical generator is simply a means of converting mechanical energy into electrical energy. In its simplest form, a generator spins coils of wire in a magnetic field, causing the flow of electrical current in the conducting wire. The power to spin the generator comes from other forms of energy. This energy might be stored energy in fossil fuels such as coal or oil, hydroelectric power from dams, wind power from turning huge windmills, or nuclear power produced by the radioactive decay of elements. In all these cases, one form of energy is simply converted into electrical energy.
The type of electricity that is most familiar to us is electrical current. This is the flow of electrical charges through a substance called a conductor, such as a metal wire. This flow happens because some of the negatively charged electrons circling the nuclei of the conductor's atoms are held loosely. The electrons can move from one atom to the next, producing an electrical current.
Energy can no be created. An electrical generator is simply a means of converting mechanical energy into electrical energy. In its simplest form, a generator spins coils of wire in a magnetic field, causing the flow of electrical current in the conducting wire. The power to spin the generator comes from other forms of energy. This energy might be stored energy in fossil fuels such as coal or oil, hydroelectric power from dams, wind power from turning huge windmills, or nuclear power produced by the radioactive decay of elements. In all these cases, one form of energy is simply converted into electrical energy.
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