Monday, April 11, 2011

Do the Mountains Grow?


In 1850 the height of Mount Everest ,the tallest peak of the world was surveyed and estimated as 29,002 feet.In a study conducted after a century ,the height was found to be 29,028.Height increased by 26 feet.In the studies involved mountains grow slightly every year .The height of the mountains increases because of some geological process taking place in the depth leading totheir slow and spasmodic uplift .These include folding of rock layers .Uplift of those layers often accompanied faulting or dislocation of rock layers .The term orogeny collectively denotes all process leading to formation of mountains

Sunday, April 10, 2011

Did the Earth always look the same?

Look at the map of the world .Examine the outlines of continets of South America and Africa.Aren't the jutting portions of South America suiting the western portion of Africa like a jigsaw puzzle?Can these two be joined?About 90 years ago a German scientist called Alfred Wegner proved that South America and Africa were once joined together .Wegner knew that there is similarity between rock strata and plant fossils of the continents of South America and Africa.He came to the conclusion that at some remote time,these two continents had been connected ,also on the basis of several other evidences he noted.He propounted the 'Continental Drift Theory'.According to this theory ,it was surmised that all the present continents had been united to a single land mass he named 'Pangaea',surrounded by"Panthalassa'an ancestral primitive ocean.Later this single continent disintegrated and drifted into different continents as we see them today.

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SIGNS, SYMPTOMS, AND STAGES OF ALZHEIMER’S DISEASE


Alzheimer’s Disease 

SIGNS, SYMPTOMS, AND STAGES OF ALZHEIMER’S DISEASE


Alzheimer's Stages, Causes & Risk Factors
Alzheimer’s disease is a disorder that affects millions of older adults and causes more worry for people over 55 years of age than any other condition. Suspecting you or a loved one may be exhibiting signs and symptoms of Alzheimer’s disease can be a stressful and emotional experience for everyone involved. Of course, even if your family history includes Alzheimer’s disease and you find yourself forgetting things, it doesn’t necessarily mean you have this disease. Even when you fear the worst, it is important to share your concerns and seek expert advice. The earlier you recognize the symptoms of Alzheimer’s disease and seek help, the better your chances of getting the care you need and maximizing your quality of life.

What is Alzheimer’s disease?

Alzheimer’s disease is the most common form ofdementia,a serious brain disorder that impacts daily living through memory loss and cognitive changes. Although not all memory loss indicates Alzheimer’s disease, one in ten people over 65 years of age, and over half of those over 85 have Alzheimer’s disease. Currently, 26 million people worldwide have this dementia, and over 15 million Americans will be affected by the year 2050.
Symptoms of Alzheimer’s disease usually develop slowly and gradually worsen over time, progressing from mild forgetfulness to widespread brain impairment. Chemical and structural changes in the brain slowly destroy the ability to create, remember, learn, reason, and relate to others.  As critical cells die, drastic personality loss occurs and body systems fail.

Who is at risk of Alzheimer’s disease?

  • The primary risk factors of Alzheimer’s are age, family history, and genetics. However, there are other risk factors that you can influence. Maintaining a healthy heart and avoiding high blood pressure, heart disease, stroke, diabetes, and high cholesterol can decrease the risk of Alzheimer’s. Watch your weight, avoid tobacco and excess alcohol, stay socially connected, and exercise both your body and mind.
  • Early-onset Alzheimer’s affects patients under the age of 65. This relatively rare condition is seen more often in patients whose parents or grandparents developed Alzheimer’s disease at a young age, and is generally associated with three specific gene mutations (the APP gene found on chromosome 21, the PSI gene on chromosome 12, and the PS2 gene on chromosome 1).
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Can Earthquake be predicted?

Earthquakes are terrible.It can devastate large areas and takes lives of millions .The earthquake that took in Equador in 1906 had the power of 300 hydrogen bomb.That which happened in China in 1976 had the power of 1000 hydrogen bombs.In this quake that occurred in Tang Shan 3 lakh people were perished.


The crust of the earth when subjected to forces breaks along fractures resulting in earthquakes .When the waves originating from the sight of the fracturing move upward and reach the surface ,the earth seams to shake,bringing about large scale destruction.

Man had attempted to study earthquakes from ancient times,1500 years ago a Chinese mathematician Chang Heng made a device to detect earthquakes.made of pendulum that could respond to the slightest movement of earth ,fixed to a huge 2m diameter vessel,we don't know how efficient this device had been.



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Saturday, April 9, 2011

ScienceShot: Newfound Asteroid on Earth's Tail

Don't panic, but Earth has a celestial stalker. An asteroid discovered last fall moves in roughly the same orbit as Earth does. However, there's no need for a restraining order. Computer models indicate that for the foreseeable future, the object (denoted with an arrow in the photo) will stay at least 19 million kilometers away from our planet and, therefore, doesn't threaten a collision. Right now, the asteroid, dubbed 2010 SO16, is making one of its 
closest approaches to Earth, researchers at the Armagh Observatory in the United Kingdom report in April's Monthly Notices of the Royal Astronomical Society. Relative to Earth, the asteroid, which likely ranges between 200 meters and 400 meters across, moves in a horseshoe-shaped path that sometimes carries it to the far side of the sun. Simulations suggest that unlike the paths followed by three other known asteroids in such orbits, 2010 SO16's orbit has been stable for at least 250,000 years and will likely remain so for at least 200,000 years into the future. 



A long-lived horseshoe companion to the Earth

We present a dynamical investigation of a newly found asteroid, 2010 SO16, and the discovery that it is a horseshoe companion of the Earth. The object's absolute magnitude (H=20.7) makes this the largest object of its type known to-date. By carrying out numerical integrations of dynamical clones, we find that (a) its status as a horseshoe is secure given the current accuracy of its ephemeris, and (b) the time spent in horseshoe libration with the Earth is several times 10^5 yr, two orders of magnitude longer than determined for other horseshoe asteroids of the Earth. Further, using a model based on Hill's approximation to the three-body problem, we show that, apart from the low eccentricity which prevents close encounters with other planets or the Earth itself, its stability can be attributed to the value of its Jacobi constant far from the regime that allows transitions into other coorbital modes or escape from the resonance altogether. We provide evidence that the eventual escape of the asteroid from horseshoe libration is caused by the action of planetary secular perturbations and the stochastic evolution of the eccentricity. The questions of its origin and the existence of as-yet-undiscovered co-orbital companions of the Earth are discussed.





Friday, April 8, 2011

Are the deserts expanding?

More than one fifth of the area of India is occupied by Thar Desert,Africa by Sahara Desert, China by Gobi  desert,South America By Atacama desert.The arid and semi arid lands constitute about two fifth of India where an estimated 200 million people are living.Deserts arid and semiarid regions of the world receive an average of less than 350 millimeter rain every year .These cover about 43 percent of earth's  land
surface.
 About 4500 years ago,the Harappan civilization flourished in regions now occupied by Thar desert.Rhinos and Elephants roamed in the forests that once grew there .large scale deforestation and climatic changes gradually converted the region into a desert. The Rajasthan desert is one of the  most densely populated deserts of  the world.The density of population is 48 persons per square kilometer. Rapid  increase in live stock population and increased cultivation  resulting in ploughing more  and more increased vulnerability of fertile soil if any  left to soil erosion

The deserts of the world show signs of expansion with time . Sahara desert is spreading southward as much as 50 km per year in some places . It has engulfed about 6500,000 square kilometers  of arable land during the last century.The situation is not different in South America ,West Asia,China and other places where desert occur.Many of the regions now occupied by deserts were once fertile.For about six centuries ,North Africa was one of the principal granaries of the ancient Roman empire.The sand dunes of Sahara covers the ruins of great cities once flourished there.

Thursday, April 7, 2011

Why is gooseberry first bitter and then sweet?

When you chew a gooseberry at first it has a bitter taste.But when you drink some water or swallow the saliva,it suddenly turns sweet.
The salts ,gallates and tannates known as poly-phenolic compounds are present in gooseberry.These salts are responsible for the said quality of fruit.When a gooseberry is chewed ,these astringent compounds envelop the taste buds of the mouth and cause temporary desensitisation. At this time the gooseberry taste bitter.Water or saliva washes down these salts and taste buds resume their sensitivity.Then they are able to sense the apparent sweetness of the gooseberry .

Wednesday, April 6, 2011

Drug to Treat a Type of Mental Retardation Shows Promise


A small study of 30 people with the most common inherited form of mental retardation has found encouraging evidence that some symptoms of the disorder can be alleviated with drugs. Some patients with Fragile X syndrome who received an experimental drug showed reductions in repetitive behaviors, hyperactivity, inappropriate speech, and social withdrawal. However, the drug affected only patients with a particular genetic alteration—a discouraging sign, perhaps, for those without that marker, but a potentially useful tool for identifying the patients most likely to respond to treatment.
As recently as 10 years ago, the idea of reversing mental retardation was unthinkable. That's because many of these conditions result from genetic glitches that derail brain development even before birth. But recent studies with mice and other animals have given researchers hope that it may be possible to develop treatments that improve cognition and behavior in conditions like Fragile X syndrome, in which a mutation to a gene on the X chromosome makes part of the chromosome look unusually thin, and Rett syndrome, another common cause of mental retardation.
One of the hottest prospects to emerge for treating Fragile X syndrome is a class of drugs that block a receptor in the brain called metabotropic glutamate receptor 5 (mGluR5). This receptor plays a role in protein synthesis at the junctions between nerve cells, and it becomes hyperactive as a result of the gene mutation that causes Fragile X. Blocking this receptor, the thinking goes, helps restore its activity to a normal level.
Other studies have reported that mGluR5-blocking drugs appear to have only moderate side effects, such as fatigue, in humans, but the new study is the first systematic report on behavioral changes in people with Fragile X. The 30 patients, all men between the ages of 18 and 35, were part of a phase II clinical trial sponsored by the pharmaceutical company Novartis, which makes the drug, called AFQ056. Half of the patients received AFQ056 for 4 weeks, then a placebo for 4 weeks. The other half took the placebo first, then the drug. Neither the patients, their caregivers, nor the researchers knew which group a patient had been assigned to until after the study.
To assess a patient's behavior before and after treatment, the researchers, led by S├ębastien Jacquemont, a medical geneticist at Centre Hospitalier Universitaire Vaudois in Lausanne, Switzerland, and Baltazar Gomez-Mancilla, a neurologist at Novartis Institutes for Biomedical Research in Basel, Switzerland, had his caregiver—typically a parent—fill out a battery of standardized questionnaires. At first, the drug seemed to have had no effect, says Gomez-Mancilla. "We were really puzzled," he says.
But when the team reexamined the data, they discovered that seven patients with a particular genetic signature had shown reduced repetitive behaviors, such as rocking back and forth and clapping, and other behavioral improvements after treatment. Some parents told the researchers they'd been more able to engage and interact with their children while they were taking the drug, Gomez-Mancilla says. Some reported fewer disruptive behaviors, such as tantrums. The researchers did not see any evidence of improvements in learning and memory, Gomez-Mancilla says, but he thinks such cognitive changes might require longer treatment times.
The Fragile X patients who responded to AFQ056 all had a "fully methylated" version of the control region of theFMR1 gene, the gene that is mutated in Fragile X. Methlyation is a chemical modification to DNA that turns a gene off, and the patients who responded to the drug appeared to have a completely inactive FMR1 gene. The others had a partially active FMR1 gene. Why this would make a difference in how people respond is still an open question, Gomez-Mancilla says. The researchers report their findings online 5 January in Science Translational Medicine.
"It's hopeful, but it's still very small numbers," says Stephen Warren, a geneticist and veteran Fragile X researcher at Emory University in Atlanta. The idea of using methylation as a biomarker to determine who might respond to this type of treatment is potentially exciting, says Ben Philpot, who studies neurodevelopmental disorders at the University of North Carolina, Chapel Hill. But he shares Warren's sense of caution: "They really need to replicate this in a larger group."
That's precisely what researchers at Novartis are trying to do now. In November, they began recruiting for a larger clinical trial that will test the effects of AFQ056 in 160 people with Fragile X. This time, the researchers will test for methylation of the FMR1 gene at the outset, and patients will take the drug for 3 months.

Is Global Warming Making Tibet Dustier?


SAN FRANCISCO, CALIFORNIA—Sediments taken from the bottom of a lake on the Tibetan Plateau suggest that changes in wind patterns caused by global warming may be making the area dustier. That trend could accelerate the melting of crucial glaciers in the Himalayas and affect already imperiled water supplies.
Tricky connections. Global warming may be increasing winds that blow dust onto the Tibetan Plateau, and the sunlight-absorbing dust may be accelerating the melting of glaciers there
Jessica Conroy, a graduate student in paleoclimatology at the University of Arizona in Tucson, and colleagues collected sediment cores from the bottom of Kiang Lake in southwestern Tibet using equipment suspended from rafts. The cores track the history of climate in the region back to 1050 C.E. According to Conroy, who presented the data here at the fall meeting of the American Geophysical Union on 15 December, the amount of fine-grained dust in the lake sediment increased over the 20th century. Finer dust arrives from distant desert regions hundreds of kilometers away, suggesting stronger winds with the power to deliver the material.
Scientists have previously noted the rise of dust in the region but attributed it to the increase in agriculture, grazing, and other relatively local developments. Data Conroy presented showed that dusty periods coincide with summers when a Northern Hemisphere atmospheric phenomenon called the Arctic Oscillation is in a "positive phase." A positive phase of this pattern in the summer leads to stronger winds in desert areas to the north of the lake as well as south of the Himalayas.
Global warming seems to be keeping the Arctic Oscillation in its positive phase more often, which Conroy says could mean that climate, not just changes in the local landscape caused by human activity, could be making southwestern Tibet dustier. Lonnie Thompson, a paleoclimatologist at Ohio State University in Columbus, who did the earlier work noting the rise of dust, says he was "impressed" with the data and called the work "thoughtful." The findings mirrored patterns he had documented within ice in a Himalayan glacier called Dasuopu, "particularly the increase in the past century or so of dust," he says. Conroy's hypothesized link between dust levels and the Arctic Oscillation "probably warrants more investigation," Thompson says.
"It's going to continue to be dusty in this region, and dust can accelerate the melting of the glaciers in the Himalayas," says Conroy. That's because the dust lands on the white ice and makes it darker, absorbing radiation and accelerating melting in the Himalayas. These glaciers, which provide water for hundreds of millions of people across Asia, are in serious danger—although a well-documented typographic error in the 2007 IPCC report exaggerated the rate of their disappearance. Dust also warms the air above the Tibetan Plateau, enhancing monsoon circulation patterns, which could affect rain and alter rainfall patterns across the southern Asia.

Monday, April 4, 2011

ScienceShot: Impacts Leave Marks on Rings of Saturn and Jupiter

Whizzing asteroids and comets have battered Earth and all the other solid bodies of our solar system over the eons, but the ethereal rings of the giant planets seemed immune. No longer. In two papers published online today in Science, researchers report that comet impacts in recent decades have left their mark on the rings of both Saturn and Jupiter. In August 2009, the orbiting Cassini spacecraft caught sight of 20-meter-high corrugations rippling across 1500 kilometers of Saturn's inner C ring (regular, narrow bright bands, above), which is only about 10 meters thick. The corrugations turn out to be one continuous wave spiraling outward like the groove in a vinyl LP record. And in 2007, the New Horizons spacecraft on its way to Pluto imaged two wave sets spiraling through each other in the faint, dusty ring of Jupiter. One Jovian wave appears to be still on the move 13 years after fragments from comet Shoemaker-Levy 9 hit the ring on their way to pummeling Jupiter in 1994. But for any impacting object to hit a tenuous ring hard enough to tilt it and set off such reverberations, both teams agree, it would first have to disintegrate into a cloud of fine debris that can hit a broad area of ring. That's just what Jupiter's gravity did to Shoemaker-Levy 9. 

Friday, April 1, 2011

A Bacterium That Acts Like a Toothbrush


Researchers have identified a new ally in the war against tooth decay: an enzyme produced by a mouth bacterium that prevents plaque formation. The finding could eventually lead to the development of toothpaste that harnesses the body's own plaque-fighting tools.
The human mouth is awash with bacteria. More than 700 species thrive in the hot, moist conditions, including Streptococcus mutans, one of the main components of plaque. Clinging to the teeth in thin layers called biofilms, S. mutans digests sugars and produces acids that can eat into enamel and cause cavities. Other bacteria are more gracious guests. In 2009, for example, scientists found that S. salivarius, a type of bacterium found on the tongue and other soft tissues in the mouth, decreases the buildup of S. mutans biofilms.
Hidenobu Senpuku, a biologist at the National Institute of Infectious Diseases in Tokyo, and colleagues wanted to know what substance conferred S. salivarius's cavity-fighting powers. Using chromatography, a method that divides the molecules in a mixture based on charge or size, they separated out individual proteins from samples of the microbe. The scientists then mixed each kind of protein with S. mutans cells and measured which cultures grew the smallest amount of biofilm on plates in the lab. The protein FruA, an enzyme that breaks apart complex sugars, was the most powerful biofilm blocker.
The researchers also found that a form of FruA, produced by the common fungus Aspergillus niger and available off-the-shelf, stymies plaque equally well. This commercial FruA worked despite the fact that its amino acid sequence is somewhat different from that of S. salivarius FruA. That might speed the development of toothpastes that include FruA, says Senpuku.
The findings, reported in Applied and Environmental Microbiology, are not a license to eat all the candy you want, however. When researchers increased the concentration of sucrose, a type of sugar, in mixtures containing S. salivarius FruA and S. mutans, the beneficial bacterium lost its ability to prevent biofilm formation. The authors write that this observation may help explain why a 1996 study found that FruA contributed to cavity formation in rats.
Mary Ellen Davey, a microbiologist at the Forsyth Institute in Cambridge, Massachusetts, agrees that the findings could spur the development of better toothpaste. But she says that won't be an easy task. Finding "the formulation that would 'guarantee' that the enzyme remained enzymatically active on the shelf of your favorite drug store is a big challenge," she says.