Hurricanes

Hurricanes affecting the United States usually begin as late summer storms over Africa or the Caribbean Sea/gulf of Mexico. Cyclonic storms in west Africa move onto the Atlantic Ocean in the equatorial region and are blown west-ward by the trade winds. Moving over warm water (at least 80F), surrounded by warm and humid air, and with weak upper-level winds, a cyclonic circulation can build toward hurricane strength (74 mph and highter). Surface winds converge at the core (eye) of the hurricane and race upward, releasing latent heat. Nearing the Western Hemisphere and moving into higher latitudes, hurricane paths veer right (coriolis effect) and commonly hit the United States. Much damage and many deaths can result when the large mound of seawater beneath the hurricane eye surges on land at heights over 20ft.

Ocean waves do not travel as a physical mass like streams on land Rather, ocean waves are pulses of energy moving through the water body, causing water particles to rotate in place, similar to the passage of seismic waves.

Most waves are created by winds blowing across the water surface. The height of a wave depends on wind velocity, length of time the wind blows, length of water the wind travels across, and consistency of wind direction. On rare occasions, the various waves moving through the ocean will briefly synchronize and produce rogue waves up to 34-m (112_ft) high.

The distance between successive waves is the wavelength, and the time for two waves to pass a common point is the period. Ocean or lake waves cause orbital motion in water to depths of one-half wavelength. Velocity of waves in miles per hour is approximately 3.5 times the wave period in seconds.

When a wave moves into shallow water, its base is slowed by friction with the sea floor. When waves slow, their lengths decrease and their heights grow. When the height-to-wavelength ratio reaches about 1:7, a wave topples forward as a breaker.

In summer, waves have shorter heights and lesser lengths, causing sand to be pushed onto beaches. During winter, the backwash from taller waves, separated by greater wavelengths, drags beach sand offshore to be stored as submarine sandbars. Beach sand provides excellent protection for coastlines under heavy wave attack. Loose sand grains absorb tremendous amounts of wave energy, then quickly fall back into place.

A wave approaching a coastline that has different water depths will refract or bend as the wave portion in shal-lower water slows more than the portion in deeper water. When waves strike the beach at an angle, they create a long-shore current that carries beach sand along the coastline as a “river of sand”. Many beaches and where the sand pours into submarine canyons and flows downslope into deep water.

Humans have major effects on the coast. We build dams across rivers that prevent sand from reaching the beaches and mine tremendous quantities of sand to make concrete and glass. This results in reduced volumes of beach sand, which allows greater wave attack on sea cliffs, where expensive buildings commonly are built. Humans build groins, jetties, and breakwaters to try to control waves and sand movement, and we place riprap and concreate walls to try to stop wave attack.

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Natural disaster

Most of the death and destruction from natural disasters comes via severe weather.

Solar radiation is received in abundance between 32 N and 34S latitudes. Much of this heat is transferred in water vapor by winds moving aloft toward the poles. Cold polar air is dense and flows equatorward. The midlatitudes are the transfer zone between the equatorial and polar air masses; they have the most severe weather.

Where tropical air in the heat-expanded troposphere meets the cold, compressed polar air, a west-to-east high-level air flow exists-the fast- moving, polar-front jet stream. The position of the polar jet migrates across the united States with the seasons. In the summer, it is over Canada: in the winter, it is near the Gulf of Mexico. The polar jet stream plays a large role in moving heat and air masses and is involved in many severe weather situations.

The paths of large, moving air and water masses are deflected by the force of the Earth’s rotation. In the Northern Hemisphere, moving masses veer to their right, in the direction of movement; this is the Coriolis effect. In the Southern Hemisphere, moving objects veer to their left.

Water has a remarkable ability to absorb and release heat. Energy is absorbed in water vapor during evaporation (latent heat of vaporization) and released during precipitation. Energy is absorbed in liquid water during melting latent heat of vaporization) and released during precipitation. Energy is absorbed in liquid water during melting (latent heat of fusion) and released during precipitation as snow.

Air masses vary in their temperature and water-vapor content. Different air masses do not readily mix; they are separated along boundaries called fronts. Much severe weather occurs along fronts.

Rotating air bodies create some of the most severe weather via thunderstorms, tornadoes, and hurricanes. In the Northern Hemisphere, rotation is counterclockwise as cyclonic circuation. Cyclones have a low-pressure core, so surface winds flow inward toward toward the core, feeding a large updraft of rising air that cools to form clouds and sometimes rain. Many of the largest cyclonic circulations are linked to troughs (large bends concave toward the North Pole) in the polar jet stream. Intense cyclones a few miles across can be thunderclouds commonly producing heavy rain, lightning, thunder, and hail, and sometimes spinning off even smaller-radius cyclones-tornadoes. The smaller the redius of a rotating air mass, the faster its wind speeds. Tornado winds can exceed 300 mph.

Heat waves are silent killers that prey on the elderly. Droughts are years of rainfall shortage. In the central United States, droughts have resulted from high-pressure ridges (large bends convex toward the North Pole) in the polar-front jet stream that foster anticyclonic circulation. An anticyclone rotates clockwise with dry air descending down its core, warming further, and evaporating moisture from the lands below.

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Space Debris

Space debris colliding with Earth are primarily rocky (stones), metallic (irons), or ices. Metallic or stony bodies are called meteorites if less than 100-m diameter and asteroids if greater than 100-m diameter; icy masses are comets. Irons are the most common from found by collectors because they pass through the atmosphere more readily, are more resistant to weathering, and are more easily recognized. Impact scars are hard to find on Earth because they are destroyed by plate-tectonic actions and the agents of erosion. Conversely, the geologically dead Moon is a museum of impact scars.

Asteroids abound in a Sin-orbiting belt between Jupiter and Mars. The strong gravitational pull of the massive planet Jupiter sends collided fragments outbound on collision courses with nearby planets, including Earth.

Comets surround the Solar System in a vast envelope known as the Oort cloud. Some comets are pulled inward close to the Sun and may collide with the Sun or a Planet, as in July 1994, when the Shoemaker-levy 9 comet collided with Jupiter.

About 100,000 million meteoroids enter Earth’s atmosphere every 24 hours. Most are small and burn up due to atmospheric friction before reaching 35 miles above ground. Up to 1,000 tons of materials are added to Earth’s surface each day.

Meteoroids hit Earth’s atmosphere at speeds from 25,000to 70,000 mph; some are destroyed on impact, some are deflected into space, and others are slowed by friction as they pass through the atmosphere. Meteoroids weighing more than 350 tons are slowed little by the atmosphere and may hit the ground at high speeds, explode and excavate craters.

The impact of a large asteroid generates such tremendous heat and pressure that much of the asteroid and crater rock is vaporized. Rocks in the crater, and debris throw out of the crater, are broken, melted, and vaporized; minerals have new high-pressure atomic structures and include forms such as diamonds. As the initial or transient crater is emptied, the crater bottom rebounds upward, and the fractured walls slide inward toward the crater center, forming a final, enlarged crater. The crater may be 100 times wider than deep.

Life on Earth is subjected to great strees by an impact. A large asteroid impact can generate an earthquake over magnitude 11; cause widespread wildfires; create nitrous oxides in the atmosphere that fall as acid rain; and place dust in the atmosphere that blocks incoming sunlight to create “winer”. After the dust settles, water vapor and CO2 remain in the atmosphere, causing a global-warming “summer”. Additionally, if the impact occurs in the ocean, tsunami of 1-to 3-km height can occur.

About 50 house-size bodies pass between the Earth and Moon each day, but the Earth is protected by its atmosphere. It is difficult to estimate how often large bodies impact Earth because plate tectonics and erosion destroy the evidence. However, looking at the Moon’s surface indicates Earth receives a crater greater than 15-mi diameter every 1.33 million years.

Statistically, your risk of being killed by a meteoroid impact is greater than that of dying by flood or tornado. We have the ability to locate incoming meteoroids and could possibly change their paths by sending explosives or a rocket out to redirect them.

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Stretching is an effective way to achieve fitness

Cats do it sleeping or leaping. Sports persons do it as part of the compulsory routine. It’s recommended for air travelers, taught during yoga lessons, suggested before gym workouts. Most fitness programmes begin with it. Techies are asked to do it all the time.

No, it is not prayer. It is getting up and stretching your back and arms as far as they will go. For instant energizing.

Stretching is a powerful part of any exercise programme, says an advisory from the Mayo Clinic. In whatever way you choose to abuse your body in a gym-treadmilling, weightlifting, stationary biking-you need to stretch out those sore muscles before you shower. Aerobic training may lead muscles to contract and flex.

You need to unlock them for balance. So stretch.

Stretching is beneficial by itself, say doctors. It increases flexibility. Flexible muscles make tasks such as bending, lifting and catching the peak-hour city bus easy and throwing darts (paperweights?) at the boss’s picture accurate. Stretching improves the range of motion in your joints (better to kick the seat in front).

Stretching improves circulation –internal and external. Stretching promotes better posture. You can sit straight till the guy behind mumbles darkly about what he’ll do to your anatomy once outside. Stretching can relieve stress. Stretching will help prevent injury by preparing you for activity. You’ll run faster, man Stretch anytime, anywhere, unless you have a chronic condition or an injury.

In which case, consult your docor physiotherapist for the best way to stretch.

For computer users stretching is part of the prescription. Repetitive strain on the back, arms and legs is caused by bad posture and long hours of sitting or standing, says Dr. Phani Raj, consultant ortho surgeon. Incorrect computer placement, lack of eye-monitor alignment, poorly designed key-boards and chair could cause muscle tightness. Stretching will help realign the body, unravel the strain. “Make stretching a habit when you’re on long distance flights”’ says Dr. Ali, who makes the well-being of co-travellers his business. “Hanging legs for long will restrict blood flow to the calf muscles. Deep vein thrombosis is a possibility”. The economy class is economically, not ergonomically designed, he warns. “Get up every two hours to stretch your legs. If you’re hesitant to walk among snorers, munchers and movie watchers keep pedaling in your seat. Stretching on flights is a life-saver.” “A stretch rutine is a must before a dance routine,” says Rad-hika Shurajit, dancer/choreographer. “If you go on stage without warming up first, you’ll take 10 minutes to catch your breath.” The heavy foot-tapping and the half-mandi (squat) positions attack the knee joints, leaving some 90 per cent of dancers with knee and low-back problems, she says. “Do mild stretches before and stretch to cool down after the performance.” Not all of us are blessed with bodies aligned for dancing, she points out. Classical postures are difficult and may leave the body battered. “I insist that my students do exercises such as leaning forward, head roll and hand stretches-straight or in circles. Thankfully, there is more awareness about warm-up stretches now than when I started dancing.”

“Hey, I can’t do without stretching” said Vidya Pillai, snooker girl, “The pressure of the game makes muscles go stiff. You have no choice but to stretch your arms, legs and back to de-stress. You can’t chew gum decently” Back stretches and rotating arms are pretty essential when you’re playing 7 frames, she said. Players the world over concentrate, do breathing exercises. “You can also stretch your head around the neck if it doesn’t distract the opponent at the table.” Cricket or cueing, teams attend camps before tournaments to do patterned stretches. “Ideally, start the day with about of stretching and between games stretch to relax muscles.”

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The Last 10,000 Years of Human History

The long, nearly flat population curves in certainly masks a number of small-scale trends, both upward and downward. The fossil record is not rich enough to plot a detailed record, but surely at times when weather was pleasant and food from plants and animals was abundant, the human population must have risen. Conversely, when weather was harsh, food was scarce, and diseases were rampant, the human population must have fallen.

The nearly flat population growth curve began to rise more rapidly by about 8,000 years ago when agriculture became established and numerous species of animals were domesticated. The world population is estimated to have been about 8 million people by 10,000 years ago. After the development of agriculture and the taming of animals removed much of the hardship form human existence, the population growth rate is likely to have increased from about 0.0015 percent to 0.036 percent per year, yielding a net gain of 360 people per million per year. This heightened rate of population growth probably raised the number of humans to about 200 million alive at 2,000 years ago.

As humans continued to improve their ability to modify the environment with better shelter and more reliable food and water supplies, the world population grew at faster rates. From about1C.E to 1750, world population grew to about 800 million. Growth was at an average rate of 0.056 percent per year, or another 560 people were added per million per year.

The eighteenth century saw many of the intellectual advances that set the stage for the present phase of cultural change. At long last, the causes of many diseases were being recognized, and the principles of public health were being established. Advances in the medical world greatly improved the odds for the survival of individual humans through their reproductive years. No longer were many mothers and great numbers of children dying childbirth and infancy. Throughout the history of the human race, high rates of birth were required to offset high rates of infant mortality and thus maintain a viable- sized human population.

The eighteenth century saw death rates drop dramatically, but birth rates remained high and population doubling times dropped dramatically, thus population size soared. About 1810, the human population reached 1 billion; by 1925, it had grown to 2 billion; in 1960, it reached 3 billion; by 1974, it was 4 billion; by early 1987, it was 5 billion; in 1999, it reached 6 billion, and is heading toward 7 billion in 2012. Notice the continuing decline in the number of years it takes for a net gain for another I billion people on earth; the effect of exponential growth is racing ahead.

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Does the Body Have a Set Point for Weight?

The set point theory of weight maintenance espouses the notion that weight is closely regulated by the body. It proposes that humans have a genetically predetermined body weight or body fat content, which the body attempts to defend. Some research suggests that the hypothalamus monitors the amount of body fat in humans and tries to keep that amount constant over time. This regulation of body fat content is referred to as a “set point.” You have already seen in this chapter that the hormone leptin forms one communication link between adipose cells and the brain that allows for some weight regulation.

In the major studies of humans cited to support the set-point theory, volunteers who lost weight through starvation later ate in a way to regain their original weight or a little more. In addition, studies in the 1960s using prisoners with no history of obesity found it was hard for some men to gain weight. This was supported by later studies (see the previous section on thermo genesis). Also, after an illness is resolved, a person generally gains lost weight.

Sound physiological evidence also suggests that body weight tends to be regulated. If energy intake is reduced, the blood concentration of the thyroid hormones fall, and the metabolic rate slows. In addition, lower body weight decreases the energy cost of each future weight-bearing activity, and the total energy used by lean tissue falls because some of these tissues are also lost. Furthermore, the enzyme used by adipose and muscle cells to take up fat from the bloodstream (lipoprotein lipase) often increases its activity. Through these changes, the body resists further weight loss.

If a person overeats, I the short run the metabolic rate tend to increase. This causes some resistance to weight gain. People often recognize the body’s resistance to weight loss when dieting but do not think much about the resistance to weight gain after eating a big holiday meal. However, in the long run, resistance to weight gain is much less than resistance to weight loss. When a person gains weight and stays at that weight for a while, the body tends to defend the new weight.

Arguments against the set-point theory cite the fact that, during pregnancy, women slowly increase body weight and fat. Also an average person’s weight does not remain constant throughout adulthood; it usually increases slowly, at least until old age. This means that a person must be able to shift his or her set point. It is also argued that, if an individual is placed in a different social, emotional, or physical environment, weight can become markedly higher or lower and is maintained. These arguments suggest that humans, rather than having a set point determined by genetics or number of adipose cells, actually settle into a particular stable weight based on an interaction between nature and nurture influences.

In the final analysis, we must bear much of the responsibility for weight maintenance ourselves since set point is weaker in preventing weight gain than in preventing weight loss. The odds are against the likelihood that, even with a set point helping us, we can avoid creeping weight gain in adulthood without attention to this tendency.

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Type 2 diabetes

Type 2 diabetes typically begins after age 40. This is the most common type of diabetes, accounting for about 90% of the cases diagnosed in North Americans, Asian Americans, Native Americans, and Pacific Islanders are at particular risk. The number of people affected with this form of diabetes is especially on the rise; primarily because of wide spread inactivity and obesity in our population. In fact, recently there has been a substantial increase in type 2 diabetes in children, due mostly to an increase in overweight in this population (coupled with limited physical activity). This type of diabetes is also genetically linked, but the initial problem is not with the beta cells of the pancreas. Instead, it arises with the insulin receptors on the cell surfaces of certain body tissues, especially muscle tissue. In this case, blood glucose is not readily transferred into cells, so the patient develops hyperglycemia as a result of the glucose’s remaining in the bloodstream. The pancreas attempts to increase insulin output to compensate, but there is a limit to its ability to do this. Thus, rather than insufficient insulin production, there is an abundance of insulin, particularly during the onset of the disease. As the disease develops, pancreatic function can fail, leading to reduced insulin output. Because of the genetic link for type 2 diabetes, those who have a family history should be careful to avoid risk factors such as obesity, a diet rich in animal and other solid fats, and high glycemic load foods, and inactivity. Being tested regularly for hyperglycemia is also important.

Many cases of type 2 diabetes (about 80%) are associated with obesity (especially fat located in the abdominal region), but the hyperglycemia is not directly caused by the obesity. In fact, some lean people also develop this type of diabetes. Obesity associated with oversized fat cells simply increases the risk for insulin resistance by the body, in turn increasing the risk for type 2 diabetes.

Type 2 diabetes linked to obesity often disappears as weight is lost. Achieving a healthy weight should be a primary goal of treatment, but even limited weight loss can to better blood glucose regulation. Oral medications can also help. Some examples are medications that reduce glucose production by the liver (metformin [glucophage]), increase the ability of the pancreas to release insulin (glipizide [glucotro]), and increase the body’s response to its own insulin (rosiglitazone [avandia]). Another class of oral agents used works by delaying carbohydrate digestion and glucose absorption (acarbose [precose]). A tablet is taken with the first bite of each meal and may be combined with other therapy.(Note that pregnant women cannot use these oral medications because they will affect the blood glucose of the developing fetus.)

Sometimes it may be necessary to provide insulin injections in type 2 diabetes because nothing else is able to control blood glucose. (This eventually becomes the case in about half of all cases of type 2 diabetes.) Regular physical activity also helps the muscles take up more glucose. And a regular meal pattern, with an emphasis on control of energy intake, consumption of low glycemic load foods, with ample fiber, is important therapy. Note that nuts fulfill the last two goals. An almost daily intake of nuts was even shown to reduce the risk of developing type 2 diabetes in one recent study.) Some intake of sugar is fine with meals, but again these must be substituted for other carbohydrates, not simply added to the meal plan. Distributing carbohydrates throughout the day is also important, as this helps minimize the high and low swings in blood glucose concentrations. Moderate alcohol use is fine (one serving per day). One recent study showed that this practice substantially reduced heart attack risk in people with type 2 diabetes. Still, the person must be warned that alcohol can lead to hypoglycemia and that the person must test him- or herself regularly for this possibility. Supplemental vitamin E may also be prescribed, as was discussed for type 1 diabetes, but again the benefits of such a practice are in doubt.

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