Science Knowledge

10 Unsolved Mysteries -> How Many Elements Exist?

noreply@blogger.com (Science Knowledge) — Fri, 27 Jan 2012 09:36:00 PST

The periodic tables that adorn the walls of classrooms have to be constantly revised, because the number of elements keeps growing. Using particle accelerators to crash atomic nuclei together, scientists can create new “superheavy” elements, which have more protons and neutrons in their nuclei than do the 92 or so elements found in nature. These engorged nuclei are not very stable—they decay radioactively, often within a tiny fraction of a second. But while they exist, the new synthetic elements such as seaborgium (element 106) and hassium (element 108) are like any other insofar as they have well-defined chemical properties. In dazzling experiments, researchers have investigated some of those properties in a handful of elusive seaborgium and hassium atoms during the brief instants before they fell apart.

Such studies probe not just the physical but also the conceptual limits of the periodic table: Do superheavy elements continue to display the trends and regularities in chemical behavior that make the table periodic in the first place? The answer is that some do, and some do not. In particular, such massive nuclei hold on to the atoms’ innermost electrons so tightly that the electrons move at close to the speed of light. Then the effects of special relativity increase the electrons’ mass and may play havoc with the quantum energy states on which their chemistry— and thus the table’s periodicity—depends.

Because nuclei are thought to be stabilized by particular “magic numbers” of protons and neutrons, some researchers hope to find what they call the island of stability, a region a little beyond the current capabilities of element synthesis in which superheavies live longer. Yet is there any fundamental limit to their size? A simple calculation suggests that relativity prohibits electrons from being bound to nuclei of more than 137 protons. More sophisticated calculations defy that limit. “The periodic system will not end at 137; in fact, it will never end,” insists nuclear physicist Walter Greiner of the Johann Wolfgang Goethe University Frankfurt in Germany. The experimental test of that claim remains a long way off.

Source of Information : Scientific American Magazine

10 Unsolved Mysteries -> How Does the Brain Think and Form Memories?

noreply@blogger.com (Science Knowledge) — Wed, 25 Jan 2012 09:30:00 PST

The brain is a chemical computer. Interactions between the neurons that form its circuitry are mediated by molecules: specifically, neurotransmitters that pass across the synapses, the contact points where one neural cell wires up to another. This chemistry of the mind is perhaps at its most impressive in the operation of memory, in which abstract principles and concepts—a telephone number, say, or an emotional association—are imprinted in states of the neural network by sustained chemical signals. How does chemistry create a memory that is both persistent and dynamic, as well as able to recall, revise and forget?

We now know parts of the answer. A cascade of biochemical processes, leading to a change in the amounts of neurotransmitter molecules in the synapse, triggers learning for habitual reflexes. But even this simple aspect of learning has shortand long-term stages. Meanwhile more complex so-called declarative memory (of people, places, and so on) has a different mechanism and location in the brain, involving the activation of a protein called the NMDA receptor on certain neurons. Blocking this receptor with drugs prevents the retention of many types of declarative memory.

Our everyday declarative memories are often encoded through a process called long-term potentiation, which involves NMDA receptors and is accompanied by an enlargement of the neuronal region that forms a synapse. As the synapse grows, so does the “strength” of its connection with neighbors—the voltage induced at the synaptic junction by arriving nerve impulses. The biochemistry of this process has been clarified in the past several years. It involves the formation of filaments within the neuron made from the protein actin—part of the basic scaffolding of the cell and the material that determines its size and shape. But that process can be undone during a short period before the change is consolidated if biochemical agents prevent the newly formed filaments from stabilizing.

Once encoded, long-term memory for both simple and complex learning is actively maintained by switching on genes that give rise to particular proteins. It now appears that this process can involve a type of molecule called a prion. Prions are proteins that can switch between two different conformations. One of the conformations is soluble, whereas the other is insoluble and acts as a catalyst to switch other molecules like it to the insoluble state, leading these molecules to aggregate. Prions were first discovered for their role in neurodegenerative conditions such as mad cow disease, but prion mechanisms have now been found to have beneficial functions, too: the formation of a prion aggregate marks a particular synapse to retain a memory.

There are still big gaps in the story of how memory works, many of which await filling with the chemical details. How, for example, is memory recalled once it has been stored? “This is a deep problem whose analysis is just beginning,” says neuroscientist and Nobel laureate Eric Kandel of Columbia University.

Coming to grips with the chemistry of memory offers the enticing and controversial prospect of pharmacological enhancement. Some memory-boosting substances are already known, including sex hormones and synthetic chemicals that act on receptors for nicotine, glutamate, serotonin and other neurotransmitters. In fact, according to neurobiologist Gary Lynch of the University of California, Irvine, the complex sequence of steps leading to long-term learning and memory means that there are many potential targets for such memory drugs.

Source of Information : Scientific American Magazine

10 Unsolved Mysteries -> How Does the Environment Influence Our Genes?

noreply@blogger.com (Science Knowledge) — Mon, 23 Jan 2012 08:48:00 PST

The old idea of biology was that who you are is a matter of which genes you have. It is now clear that an equally important issue is which genes you use. Like all of biology, this issue has chemistry at its core.

The cells of the early embryo can develop into any tissue type. But as the embryo grows, these so-called pluripotent stem cells differentiate, acquiring specific roles (such as blood, muscle or nerve cells) that remain fixed in their progeny. The formation of the human body is a matter of chemically modifying the stem cells’ chromosomes in ways that alter the arrays of genes that are turned on and off.

One of the revolutionary discoveries in research on cloning and stem cells, however, is that this modification is reversible and can be influenced by the body’s experiences. Cells do not permanently disable genes during differentiation, retaining only those they need in a “ready to work” state. Rather the genes that get switched off retain a latent ability to work—to give rise to the proteins they encode— and can be reactivated, for instance, by exposure to certain chemicals taken in from the environment.

What is particularly exciting and challenging for chemists is that the control of gene activity seems to involve chemical events happening at size scales greater than those of atoms and molecules—at the so-called mesoscale—with large molecular groups and assemblies interacting. Chromatin, the mixture of DNA and proteins that makes up chromosomes, has a hierarchical structure. The double helix is wound around cylindrical particles made from proteins called histones, and this string of beads is then bundled up into higher-order structures that are poorly understood. Cells exercise great control over this packing—how and where a gene is packed into chromatin may determine whether it is active or not.

Cells have specialized enzymes for reshaping chromatin structure, and these enzymes have a central role in cell differentiation. Chromatin in embryonic stem cells seems to have a much looser, open structure: as some genes fall inactive, the chromatin becomes increasingly lumpy and organized. “The chromatin seems to fix and maintain or stabilize the cells’ state,” says pathologist Bradley Bernstein of Massachusetts General Hospital.

What is more, such chromatin sculpting is accompanied by chemical modification of both DNA and histones. Small molecules attached to them act as labels that tell the cellular machinery to silence genes or, conversely, free them for action. This labeling is called “epigenetic” because it does not alter the information carried by the genes themselves.

The question of the extent to which mature cells can be returned to pluripotency— whether they are as good as true stem cells, which is a vital issue for their use in regenerative medicine—seems to hinge largely on how far the epigenetic marking can be reset.

It is now clear that beyond the genetic code that spells out many of the cells’ key instructions, cells speak in an entirely separate chemical language of genetics— that of epigenetics. “People can have a genetic predisposition to many diseases, including cancer, but whether or not the disease manifests itself will often depend on environmental factors operating through these epigenetic pathways,” says geneticist Bryan Turner of the University of Birmingham in England.

Source of Information : Scientific American Magazine

10 Unsolved Mysteries -> How Do Molecules Form?

noreply@blogger.com (Science Knowledge) — Sat, 21 Jan 2012 08:42:00 PST

Molecular structures may be a mainstay of high school science classes, but the familiar picture of balls and sticks representing atoms and the bonds among them is largely a conventional fiction. The trouble is that scientists disagree on what a more accurate representation of molecules should look like. In the 1920s physicists Walter Heitler and Fritz London showed how to describe a chemical bond using the equations of then nascent quantum theory, and the great American chemist Linus Pauling proposed that bonds form when the electron orbitals of different atoms overlap in space. A competing theory by Robert Mulliken and Friedrich Hund suggested that bonds are the result of atomic orbitals merging into “molecular orbitals” that extend over more than one atom. Theoretical chemistry seemed about to become a branch of physics.

Nearly 100 years later the molecular or beta picture has become the most common one, but there is still no consensus among chemists that it is always the best way to look at molecules. The reason is that this model of molecules and all others are based on simplifying assumptions and are thus approximate, partial bunch of atomic nuclei in a cloud of electrons, with opposing electrostatic forces fighting a constant tug-of-war with one another, and all components constantly moving and reshuffling. Existing models of the molecule usually try to crystallize such a dynamic entity into a static one and may capture some of its salient properties but neglect others.

Quantum theory is unable to supply a unique definition of chemical bonds that accords with the intuition of chemists whose daily business is to make and break them. There are now many ways of describing molecules as atoms joined by bonds. According to quantum chemist Dominik Marx of Ruhr University Bochum in Germany, pretty much all such descriptions “are useful in some cases but fail in others.”

Computer simulations can now calculate the structures and properties of molecules from quantum first principles with great accuracy—as long as the number of electrons is relatively small. “Computational chemistry can be pushed to the level of utmost realism and complexity,” Marx says. As a result, computer calculations can increasingly be regarded as a kind of virtual experiment that predicts the course of a reaction. Once the reaction to be simulated involves more than a few dozen electrons, however, the calculations quickly begin to overwhelm even the most powerful supercomputer, so the challenge will be to see whether the simulations can scale up—whether, for example, complicated biomolecular processes in the cell or sophisticated materials can be modeled this way.

Source of Information : Scientific American Magazine

10 Unsolved Mysteries -> How Did Life Begin?

noreply@blogger.com (Science Knowledge) — Thu, 19 Jan 2012 08:28:00 PST

The moment when the first living beings arose from inanimate matter almost four billion years ago is still shrouded in mystery. How did relatively simple molecules in the primordial broth give rise to more and more complex compounds? And how did some of those compounds begin to process energy and replicate (two of the defining characteristics of life)? At the molecular level, all of those steps are, of course, chemical reactions, which makes the question of how life began one of chemistry.

The challenge for chemists is no longer to come up with vaguely plausible scenarios, of which there are plenty. For example, researchers have speculated about minerals such as clay acting as catalysts for the formation of the first self-replicating polymers (molecules that, like DNA or proteins, are long chains of smaller units); about chemical complexity fueled by the energy of deep-sea hydrothermal vents; and about an "RNA world," in which DNA’s cousin RNA—which can act as an enzyme and catalyze reactions the way proteins do—would have been a universal molecule before DNA and proteins appeared.

No, the game is to figure out how to test these ideas in reactions coddled in the test tube. Researchers have shown, for example, that certain relatively simple chemicals can spontaneously react to form the more complex building blocks of living systems, such as amino acids and nucleotides, the basic units of DNA and RNA. In 2009 a team led by John Sutherland, now at the MRC Laboratory of Molecular Biology in Cambridge, England, was able to demonstrate the formation of nucleotides from molecules likely to have existed in the primordial broth. Other researchers have focused on the ability of some RNA strands to act as enzymes, providing evidence in support of the RNA world hypothesis. Through such steps, scientists may progressively bridge the gap from inanimate matter to selfreplicating, self-sustaining systems.

Now that scientists have a better view of strange and potentially fertile environments in our solar system—the occasional flows of water on Mars, the petrochemical seas of Saturn’s moon Titan, and the cold, salty oceans that seem to lurk under the ice of Jupiter’s moons Europa and Ganymede—the origin of terrestrial life seems only a part of grander questions: Under what circumstances can life arise? And how widely can its chemical basis vary? That issue is made richer still by the discovery, over the past 16 years, of more than 500 extrasolar planets orbiting other stars—worlds of bewildering variety.

These discoveries have pushed chemists to broaden their imagination about the possible chemistries of life. For instance, NASA has long pursued the view that liquid water is a prerequisite, but now scientists are not so sure. How about liquid ammonia, formamide, an oily solvent like liquid methane or supercritical hydrogen on Jupiter? And why should
life restrict itself to DNA, RNA and proteins? After all, several artificial chemical systems have now been made that exhibit a kind of replication from the component parts without relying on nucleic acids. All you need, it seems, is a molecular system that can serve as a template for making a copy and then detach itself.

Looking at life on Earth, says chemist Steven Benner of the Foundation for Applied Molecular Evolution in Gainesville, Fla., “we have no way to decide whether the similarities [such as the use of DNA and proteins] reflect common ancestry or the needs of life universally.” But if we retreat into saying that we have to stick with what we know, he says, “we have no fun.”

Source of Information : Scientific American Magazine

Putting Diabetes on Autopilot

noreply@blogger.com (Science Knowledge) — Wed, 18 Jan 2012 06:51:00 PST

New devices may spare patients from monitoring their blood glucose

For millions of diabetes sufferers, life is a constant battle to keep their blood sugar balanced, which typically means they have to test their glucose levels and take insulin throughout the day. A new generation of “artificial pancreas” devices may make tedious diabetes micromanagement obsolete. In healthy people, the pancreas naturally produces insulin, which converts sugars and starches into energy. People with type 1 diabetes, however, do not produce any insulin of their own, and those with type 2 produce too little. All type 1 and many type 2 diabetics have to dose themselves with insulin to keep their bodies fueled—and doing so properly requires constant monitoring of blood sugar because appropriate dosages depend on factors such as how much patients eat or exercise. Stuart Weinzimer, an endocrinologist at Yale University, has devised an artificial pancreas that combines two existing technologies: a continuous glucose monitor, which uses an under-the-skin sensor to measure blood glucose levels every few minutes, and an insulin pump, which dispenses insulin through a tube that is also implanted under the skin.

The glucose sensor sends its data wirelessly to a pocket computer a little bigger than an iPhone that is loaded with software developed by Minneapolis-based Medtronic. The program scans the incoming data from the glucose monitor and directs the pump to dispense the correct amount of insulin.

At an American Diabetes Association meeting in June, Weinzimer and his colleagues reported that 86 percent of type 1 diabetics they studied who used the artificial pancreas reached target blood glucose levels at night, whereas only 54 percent of subjects who had to wake up to activate an insulin pump reached their target levels. Other, similar systems are in development at Boston University, the University of Cambridge and Stanford University.

Some technical glitches still need to be worked out. For example, the device occasionally has trouble adapting to drastic changes in glucose, such as those that occur after exercise. And it will have to go through more rounds of vetting, which could take years, including large-scale patient trials that will be required before the Food and Drug Administration can approve the device. Nevertheless, Weinzimer says that the enthusiastic responses h has gotten from his trial participants remind him why the long slog toward commercialization is worthwhile.

Source of Information : Scientific American Magazine

Spherical Eats

noreply@blogger.com (Science Knowledge) — Fri, 13 Jan 2012 06:49:00 PST

The chemistry of encased mussels and other edible orbs

A few years ago the renowned chef Ferran Adrià presented diners at his restaurant, elBulli, with a simple dish of brightorange caviar—or rather what looked like caviar: when the guests bit into the orbs, they burst into a mouthful of cantaloupe juice. Since that legendary bit of culinary trompe l’oeil, Adrià and other avant-garde chefs have created many more otherworldly dishes, including mussels that Adrià encases in transparent globes of their own juice.

Eating these spherical foods can evoke childlike joy as you roll the smooth balls around your mouth and explode them with your tongue. But making such confections is not so simple; a lot of chemistry goes into the process. Chefs have developed two ways to go about it: direct and reverse spherification. Both methods exploit the fact that some gelling mixtures do not set unless ions, charged molecules, are present. In the direct approach, the chef blends the food into a puree or broth that contains a gelling agent, such as sodium alginate or iota carrageenan, but that lacks coagulating ions. The cook separately prepares a setting bath that contains a source of the missing ions, such as calcium gluconate.

As soon as droplets or spoonfuls of the food fall into the bath, gelling begins. Surface tension pulls the beads into their distinctive round shape. A short dip in the bath yields liquid-filled balls encased in tissue-thin skin; a long soak produces chewy beads. The cook stops the gelling process by rinsing the beads and heating them to 85 degrees Celsius (185 degrees Fahrenheit) for 10 minutes. Reverse spherification inverts the process: calcium lactate or some other source of calcium ions is added to the edible liquid or puree—unless the food is naturally rich in calcium.

The bath contains unset gel made with deionized or distilled water, which is calciumfree. When the food goes in, the bath solution itself forms a skin of gel around it. The culinary
team at our lab has used spherification to make marbles of crystal-clear tomato water that enclose smaller spheres of basil oil. We have also found that this technique is a terrific way to make a very convincinglooking raw “egg” out of little more than water, ham broth (for the white) and melon juice (for the yolk). It tastes much better than it looks.

Source of Information : Scientific American Magazine

Gig.U Is Now in Session

noreply@blogger.com (Science Knowledge) — Tue, 10 Jan 2012 05:46:00 PST

Universities are piloting superfast Internet connections that may finally rival the speed of South Korea’s

The U.S. notoriously lags other countries when it comes to Internet speed. One recent report from Web analyst Akamai Technologies puts us in 14th place, far behind front-runner South Korea and also trailing Hong Kong, Japan and Romania, among other countries. The sticking point over faster broadband has been: Who will pay for it? Telecommunications companies have been leery of investing in infrastructure unless they are certain of demand for extra speed. American consumers, for their part, have been content to direct much of their Internet use to e-mail and social networks, which operate perfectly well at normal broadband speeds, and they have not been willing to pay a premium for speedier service.

The exception lies at the seat of learning. Universities and research institutes are always looking for a quicker flow of bits. “We think our researchers will be left behind without gigabit speeds,” says Elise Kohn, a former policy adviser for the Federal Communications Commission. Kohn and Blair Levin, who helped to develop the FCC’s National Broadband Plan—a congressionally mandated scheme to ensure broadband access to all Americans—are leading a collection of 29 universities spread across the country in piloting a network of one-gigabit-per-second Internet connections. The group, the University Community Next Generation Innovation Project—more commonly referred to as Gig.U—includes Duke University, the University of Chicago, the University of Washington and Arizona State University.

The average U.S. Internet speed today is 5.3 megabits per second, so Gig.U’s Internet would be many times faster than those available today, allowing users to download the equivalent of two high-definition movies in less than one minute and to watch streaming video with no pixelation or other interruptions. By comparison, the average Internet speed in South Korea is 14.4 megabits per second, and the country has pledged to connect every home to the Internet at one gigabit per second by 2012.

The U.S. gigabit networks will vary from site to site, depending on the approach that different Internet service providers propose to meet the diff ering needs of Gig.U members. “All our members are focused on next-generation networks, although some will need more than a gigabit, and others will need less,” Kohn says. Gig.U’s request-for-information period runs through November to solicit ideas from the local service providers upgrading to faster networks. These ideas will ultimately be funded by Gig.U members, as well as any nonprofits and private-sector companies interested in the project. Gig.U intends to accelerate the deployment of next-generation networks in the U.S. by encouraging researchers—students and professors alike—to develop new applications and services that can make use of ultrafast data-transfer rates.

Source of Information : Scientific American Magazine

10 Unsolved Mysteries -> Can Computers Be Made Out of Carbon?

noreply@blogger.com (Science Knowledge) — Sat, 07 Jan 2012 07:22:00 PST

computer chips made out of graphene—a web of carbon atoms—could potentially be faster and more powerful than silicon-based ones. The discovery of graphene garnered the 2010 Nobel Prize in Physics, but the success of this and other forms of carbon nanotechnology might ultimately depend on chemists’ ability to create structures with atomic precision.

The discovery of buckyballs—hollow, cagelike molecules made entirely of carbon atoms—in 1985 was the start of something literally much bigger. Six years later tubes of carbon atoms arranged in a chicken wire–shaped, hexagonal pattern like that in the carbon sheets of graphite made their debut. Being hollow, extremely strong and stiff,
and electrically conducting, these carbon nanotubes promised applications ranging from high-strength carbon composites to tiny wires and electronic devices, miniature molecular capsules, and water-filtration membranes.

For all their promise, carbon nanotubes have not resulted in a lot of commercial applications. For instance, researchers have not been able to solve the problem of how to connect tubes into complicated electronic circuits. More recently, graphite has moved to center stage because of the discovery that it can be separated into individual chicken wire–like sheets, called graphene, that could supply the fabric for ultraminiaturized, cheap and robust electronic circuitry. The hope is that the computer industry can use narrow ribbons and networks of graphene, made to measure with atomic precision, to build chips with better performance than silicon-based ones.

“Graphene can be patterned so that the interconnect and placement problems of carbon nanotubes are overcome,” says carbon specialist Walt de Heer of the Georgia Institute of Technology. Methods such as etching, however, are too crude for patterning graphene circuits down to the single atom, de Heer points out, and as a result, he fears that graphene technology currently owes more to hype than hard science. Using the techniques of organic chemistry to build up graphene circuits from the bottom up—linking together “polyaromatic” molecules containing several hexagonal carbon rings, like little fragments of a graphene sheet— might be the key to such precise atomicscale engineering and thus to unlocking the future of graphene electronics.

Source of Information : Scientific American Magazine

More than Child’s Play

noreply@blogger.com (Science Knowledge) — Fri, 06 Jan 2012 08:19:00 PST

Young children think like researchers but lose the feel for the scientific method as they age

If your brownies came out too crispy on top but undercooked in the center, it would make sense to bake the next batch at a lower temperature, for more time or in a different pan—but not to make all three changes at once. Realizing that you can best tell which variable matters by altering only one at a time is a cardinal principle of scientific inquiry.

Since the 1990s studies have shown that children think scientifically— making predictions, carrying out mini experiments, reaching conclusions and revising their initial hypotheses in light of new evidence. But while children can play in a way that lets them ascertain cause and effect, and even though they have a rudimentary sense of probability (eight-month-olds are surprised if you reach into a bowl containing four times as many blue marbles as white ones and randomly scoop out a fistful of white ones), it was not clear whether they have an implicit grasp of a key strategy of experimental science: that by isolating variables and testing each independently, you can gain information.

To see whether children understand this concept, scientists at the Massachusetts Institute of Technology and Stanford University presented 60 four- and five-year-olds with a challenge. The researchers showed the kids that certain plastic beads, when placed individually on top of a special box, made green LED lights flash and music play. Scientists then took two pairs of attached beads, one pair glued together and the other separable, and demonstrated that both pairs activated the machine when laid on the box. That raised the possibility that only one bead in a pair worked. The children were then left alone to play. Would they detach the separable pair and place each bead individually on the machine to see which turned it on?

They did, the scientists reported in September in the journal Cognition. So strong was the kids’ sense that they could only figure out the answer by testing the components of a pair independently that they did something none of the scientists expected: when the pair was glued together, the children held it vertically so that only one bead at a time touched the box. That showed an impressive determination to isolate the causal variables, says Stanford’s Noah Goodman: “They actually designed an experiment to get the information they wanted.” That suggests basic scientific principles help very young children learn about the world.

The growing evidence that children think scientifically presents a conundrum: If even the youngest kids have an intuitive grasp of the scientific method, why does that understanding seem to vanish within a few years? Studies suggest that K–12 students struggle to set up a controlled study and cannot figure out what kind of evidence would support or refute a hypothesis. One reason for our failure to capitalize on this scientific intuition we display as toddlers may be that we are pretty good, as children and adults, at reasoning out puzzles that have something to do with real life but flounder when the puzzle is abstract, Goodman suggests—and it is abstract puzzles that educators tend to use when testing the ability to think scientifically. In addition, as we learn more about the world, our knowledge and beliefs trump our powers of scientific reasoning. The message for educators would seem to be to build on the intuition that children bring to science while doing a better job of making the connection between abstract concepts and real-world puzzles.

Source of Information : Scientific American Magazine

Exposure to the chemicals in everyday objects poses a hidden health threat

noreply@blogger.com (Science Knowledge) — Mon, 02 Jan 2012 08:10:01 PST

Toxins All around Us

Susan starts her day by jogging to the edge of town, cutting back through a cornfield for an herbal tea at the downtown Starbucks and heading home for a shower. It sounds like a healthy morning routine, but Susan is in fact exposing herself to a rogue’s gallery of chemicals: pesticides and herbicides on the corn, plasticizers in her tea cup, and the wide array of ingredients used to perfume her soap and enhance the performance of her shampoo and moisturizer. Most of these exposures are so low as to be considered trivial, but they are not trivial at all—especially considering that Susan is six weeks pregnant.

Scientists have become increasingly worried that even extremely low levels of some environmental contaminants may have significant damaging effects on our bodies—and that fetuses are particularly vulnerable to such assaults. Some of the chemicals that are all around us have the ability to interfere with our endocrine systems, which regulate the hormones that control our weight, our biorhythms and our reproduction. Synthetic hormones are used clinically to prevent pregnancy, control insulin levels in diabetics, compensate for a deficient thyroid gland and alleviate menopausal symptoms. You wouldn’t think of taking these drugs without a prescription, but we unwittingly do something similar every day. An increasing number of clinicians and scientists are becoming convinced that these chemical exposures contribute to obesity, endometriosis, diabetes, autism, allergies, cancer and other diseases. Laboratory studies—mainly in mice but sometimes in human subjects— have demonstrated that low levels of endocrine-disrupting chemicals induce subtle changes in the developing fetus that have profound health effects in adulthood and even on subsequent generations. The chemicals an expecting mother takes into her body during the course of a typical day may affect her children and her grandchildren.

This isn’t just a lab experiment: we have lived it. Many of us born in the 1950s, 1960s and 1970s were exposed in utero to diethylstilbestrol, or DES, a synthetic estrogen prescribed to pregnant women in a mistaken attempt to prevent miscarriage. An article in the June issue of the New England Journal of Medicine called the lessons learned about the effects of fetal human exposures to DES on adult disease “powerful.”

In the U.S., two federal agencies, the Food and Drug Administration and the Environmental Protection Agency, are responsible for banning dangerous chemicals and making sure that chemicals in our food and drugs have been thoroughly tested. Scientists and clinicians across diverse disciplines are concerned that the efforts of the EPA and the FDA are insufficient in the face of the complex cocktail of chemicals in our environment. Updating a proposal from last year, Senator Frank R. Lautenberg of New Jersey introduced legislation this year to create the Safe Chemicals Act of 2011. If enacted, chemical companies would be required to demonstrate the safety of their products before marketing them. This is perfectly logical, but it calls for a suitable screening-and-testing program for endocrine-disrupting chemicals. The need for such tests has been recognized for more than a decade, but no one has yet devised a sound testing protocol.

Regulators also cannot interpret the mounting evidence from laboratory studies, many of which use techniques and methods of analysis that weren’t even dreamed of when toxicology testing protocols were developed in the 1950s. It’s like providing a horse breeder with genetic sequence data for five stallions and asking him or her to pick the best horse. Interpreting the data would require a broad range of clinical and scientific experience.

That’s why professional societies representing more than 40,000 scientists wrote a letter to the FDA and EPA offering their expertise. The agencies should take them up on it. Academic scientists and clinicians need a place at the table with government and industry scientists. We owe it to mothers everywhere, who want to give their babies the best possible chance of growing into healthy adults.

Source of Information : Scientific American Magazine

Improving Your Immune System

noreply@blogger.com (Science Knowledge) — Sun, 01 Jan 2012 07:59:00 PST

The most successful ways to help your immune system is through prevention and protection— in other words, practicing tactics like washing your hands properly, avoiding spoiled food, and staying up-to-date on your vaccines. Aside from vaccinations, none of these strategies actually affects your immune system. Instead, they help you fend off pathogens before they get inside.
Although there’s no clear-cut way to beef up your body’s defenses, some simple practices may help.

• Eat a balanced diet. There’s no immune system-boosting super food, but a balanced diet is a good basis for fighting disease. Scientists link deficiencies in folic acid and in vitamins A, B, C, and E, to poor immune-system function.

• Avoid stress. And not just the mental kind. The physical wear and tear of weight loss diets and intense exercise also damps down your immune response. So do injuries, infections, heavy drinking, and pack-a-day smoking.

• Get a proper night’s sleep. It’s obvious, but worth repeating—studies find that 8 hours of nightly sleep boosts the level of immune cells in your body.

• Be optimistic. It sounds a bit foofy, but studies have consistently found that you can get someone’s body to produce more T cells if you force them to meditate, relax, watch funny TV, or hang out with friends.

Source of Information : Oreilly - Your Body Missing Manual

Inflammation

noreply@blogger.com (Science Knowledge) — Wed, 28 Dec 2011 19:53:00 PST

As important as your body’s physical barriers are, they can’t repel all invaders. Minor cuts in your skin open a brief, tantalizing entryway to your body’s nutrient-rich interior. Tiny germs can eventually make their way through the thickest mucous coating. And while the acid in your stomach is strong enough to pickle steel, crafty microbes can survive or slip through it to your much more hospitable intestines. (For example, H. pylori, the culprit behind most heartburn-causing stomach ulcers, secretes an acid-neutralizing enzyme that protects the microbe until it gets a chance to worm its way into your stomach walls.)
When a pathogen breaches your body’s first line of defense, the lowly foot soldiers of your immune system meet it within minutes. One of your best defenders is the macrophage (which translates as “big eater”), a swollen blob of a cell that sucks in almost any foreign particle that crosses its path, including dead cells, debris, and pathogens. Once enveloped, a battery of powerful chemicals attacks the foreign particle, destroying it in minutes. A typical macrophage may swallow some hundred bacteria before it dies, finally done in by its own toxic chemicals.

A macrophage is a type of white blood cell. All white blood cells are immune system soldiers—they simply use different tactics.

For its first strike to be successful, your body needs to respond quickly and with overwhelming force. It’s not enough to wait until wandering macrophages stumble across new invaders. Your body needs to summon its defensive forces in a hurry.

Its trick is the inflammation response, your immune system’s call to arms. Your body triggers inflammation when it detects damaged tissue, intense heat, dangerous chemicals, or potential attackers. The first effect of the inflammation response is increased blood flow—your blood vessels dilate and gaps open in your cell walls so the blood can pour into the surrounding tissue. As the blood rushes in, you feel the resulting swelling, as well as pain (because the swollen tissues press on nearby nerves that carry pain signals) and heat (because of the influx of heated blood).

The main goal of the inflammation response is to stock the affected area with your body’s immune system soldiers. In addition, the added blood increases the heat, which spurs your macrophages to work harder and can alter the delicate balance of chemical reactions in the invading pathogens, throwing them off balance. (Your body uses a fever—a sudden spike in body temperature—with much the same effect when battling more stubborn enemies.)

The only time you see your white blood cells is when pus oozes from a wound. This creamy, yellow substance contains the detritus of biological warfare—brokendown tissue cells, living and dead pathogens, and scores of dead white blood cells.

Source of Information : Oreilly - Your Body Missing Manual

A Tale of Math Treasure

noreply@blogger.com (Science Knowledge) — Sun, 25 Dec 2011 05:41:00 PST

An exhibition traces the reconstruction of a long-missing collection of writings by Archimedes

There is much cheesy lore about the ancient Greek mathematician Archimedes of Syracuse: that he popularized the word “eureka”; that he used mirrors to set Roman ships on fire; that a Roman soldier killed him in 212 B.C. while he was tracing diagrams in the sand. Not only is the lore probably untrue, historians say, but it also fails to capture the true significance of his achievements, which spanned mathematics, science and engineering and inspired the likes of Leonardo da Vinci, Galileo and Isaac Newton. Some credit him with having essentially invented the basic ideas of calculus. An exhibit opening in October at the Walters Art Museum in Baltimore will showcase a decade-long effort to restore some of his longlost texts and unearth some of his previously unknown contributions. “Lost and Found: The Secrets of Archimedes” focuses on a parchment book known as the Archimedes Palimpsest.

At one point in history, all of Archimedes’ works that survived through the Dark Ages were contained in just three tomes made by 10th-century copyists in Constantinople. One, called Codex C, disappeared some time after Western European armies sacked the Byzantine capital in 1204. Then, in 1906, Danish philologist Johan Ludvig Heiberg found a book of prayers at a monastery in the city and noticed that it was a palimpsest—meaning that the parchment had been recycled by cutting up the pages of older books and scraping them clean. Among those older books, Heiberg realized, was Codex C. Armed with a magnifying lens, Heiberg painstakingly transcribed what he could read of the older text, including parts of two treatises that no other eyes had seen in modern times. One was the “Method of Mechanical

Theorems,” which describes the law of the lever and a technique to calculate a body’s center of gravity—essentially the one still used today. Another, called the “Stomachion,” appeared to be about a tangramlike game. Soon, the book disappeared again before resurfacing in 1998 at an auction in New York City. There an anonymous collector bought it for $2 million and lent it to the Walters museum. When the palimpsest reemerged, says Will Noel, who is its curator, “it was in appalling condition.” As the exhibition will display on panels and videos, imaging experts were able to map much of the hidden text using high-tech tools—including x-rays from a particle accelerator— and to make it available to scholars. Reviel Netz, a historian of mathematics at Stanford University, discovered by reading the “Method of Mechanical Theorems” that Archimedes treated infinity as a number, which constituted something of a philosophical leap. Netz was also the first scholar to do a thorough study of the diagrams, which he says are likely to be faithful reproductions of the author’s original drawings and give crucial insights into his thinking. These will be on display, but the studies go on. Netz is now transcribing the texts contained in the palimpsest, which he estimates at about 50,000 words, most written in a shorthand typical of medieval copyists. He plans to publish a critical edition in the original Greek. “It will take probably several decades to translate it into English,” he says.

Source of Information : Scientific American Magazine

How Many Glasses of Water a Day?

noreply@blogger.com (Science Knowledge) — Wed, 21 Dec 2011 07:37:00 PST

It’s the question that everyone seems to ask. And if you follow the standard advice (drink 8 to 10 glasses of water every day), your next request will be for directions to the restroom. Because unless you’re a strenuous exercise or a desert dweller, you’re unlikely to need that much water—and unless you’re carrying a horse’s bladder, you won’t hold onto it for long.

No one’s quite sure where the 8-to-10 glasses factoid started. However, medical professionals do agree on quite a few things about fluids:

• Six glasses is usually enough. If you must count, 6 glasses of water a day is probably a good rule of thumb (not a bare minimum). But the average person, doing gentle activity in a gentle climate, can probably get all the fluid they need from solid food alone (although it’s not recommended).

• Follow your thirst. Your need for water varies greatly depending on your activity level. Fortunately, your body is surprisingly good at telling you when to drink. And the idea that we’re chronically (and unknowingly) dehydrated is little more than science fiction.

• Don’t fear coffee and tea. Despite the diuretic properties of caffeine, you’ll still retain a large amount of the fluid in every cup—and even more if you’re a regular drinker of caffeinated beverages.

• Dehydration may worsen constipation. If you’re straining to pass stool, you might benefit from increasing your water intake a bit. However, results vary, and a more likely cause of constipation is inadequate fiber in your diet.

So why are we so easily misled by drinking myths that don’t hold water? Quite simply, in the era of modern science, we’re used to hearing (and accepting) startling facts. But when it comes to water, medical research is in an unusual position: proving that our common sense was right all along.

Source of Information : Oreilly - Your Body Missing Manual

What Are Probiotics and Prebiotics?

noreply@blogger.com (Science Knowledge) — Fri, 16 Dec 2011 07:33:01 PST

Probiotics are live microorganisms (bacteria or yeast) that are particularly well-suited to your digestive system. For example, lactic acid bacteria is a common probiotic that gives sourdough and yogurt their characteristic sour flavor. In your colon, lactic acid bacteria digest the sugar known as lactose and may even prevent inflammation and inhibit cancer.

However, there’s a catch. As you’ve seen, your large intestine is quite far down in your digestive system. For a probiotic to make it to its new home, it needs to pass through the inhospitable acidic environment of your stomach. Pharmaceutical companies are experimenting with special coatings that help probiotics make the hazardous journey intact, but in the meantime it’s hard to tell how effective probiotic-fortified foods really are.

Prebiotics are substances that your healthy, colon-dwelling bacteria like to munch on. Supply these bacteria with more prebiotics, and you can encourage a small population to grow. Prebiotics are naturally present in fruits and vegetables, but don’t expect to find any in a box of macaroni and cheese.

The bottom line is that both probiotics and prebiotics are based on valid nutritional science that recognizes the value of good gut bacteria. But their success as products is less clear, and it’s a good guess that you’ll get more benefit from a diet that emphasizes fruits and vegetables than one that focuses on convenience foods and nutritionally fortified drinks, no matter what miraculous new additives manufacturers toss in.

Source of Information : Oreilly - Your Body Missing Manual

The Trouble with Armor

noreply@blogger.com (Science Knowledge) — Tue, 13 Dec 2011 00:12:01 PST

The steel plates worn by medieval soldiers may have led to their wearers’ demise

On August 13, 1415, the 27-year-old English king Henry V led his army into France. Within two months dysentery had killed perhaps a quarter of his men, while a French army four times its size blocked escape to Calais and across the English Channel. Winter approached; food grew scarce. Yet in one of the most remarkable upsets in military history, a force of fewer than 7,000 English soldiers— most of them lightly armed archers—repulsed 20,000 to 30,000 heavily armored French men-at-arms near the village of Agincourt, killing thousands. Shakespeare’s play Henry V attributed the victory to the power of Henry’s inspirational rhetoric; the renowned military historian John Keegan has credited the self-defeating crush of the French charge. But a study by exercise physiologists now suggests a new reason for the slaughter: suits of armor might not be all that great for fighting.

Researchers at the University of Leeds in England placed armor-clad volunteers on a treadmill and monitored their oxygen consumption. The armor commonly used in the 15th century weighed anywhere from 30 to 50 kilograms, spread from head to hand to toe. Because of the distributed mass, volunteers had to summon great effort to swing steel-plated legs through each stride. In addition, breastplates forced quick, shallow breaths. The researchers found that the suits of armor doubled volunteers’ metabolic requirements, compared with an increase of only about 70 percent for the same amount of weight carried in a backpack.

Of course, medieval battles did not happen on treadmills. The fields at Agincourt were thick with mud, having recently been plowed for winter wheat and soaked in a heavy October shower. The French charged across 300 yards of this slop, all while suffering fire from the English archers. Combine the effort required to run in armor with that needed to slog through mud, says Graham Askew, one of the study’s leaders, and you’d expect at least a fourfold increase in energy expenditure—enough, it seems, to change history.

Source of Information : Scientific American Magazine

Why Don’t Mexicans Get Traveler’s Diarrhea?

noreply@blogger.com (Science Knowledge) — Wed, 07 Dec 2011 19:29:00 PST

If you’re a citizen of the world, you’ve probably met up with that uncomfortable phenomenon known as traveler’s diarrhea—a short episode of diarrhea that strikes thosebrave enough to visit local places and enjoy local cuisine. The odd part is that traveler’s diarrhea seems to affect only travelers. Native people can eat the same foods and emerge unscathed.

The first thing to understand is that traveler’s diarrhea needs a certain level of sanitary sloppiness to occur. In particular, it only happens if there’s some way for bacteria to pass from another person’s (or an animal’s) feces into your environment. For this reason, traveler’s diarrhea happens much less often to visitors of most first-world countries. (Although Mexicans do occasionally get diarrhea when visiting the U.S., which they call“Washington’s Revenge.”)

However, this doesn’t explain why locals have a much-reduced rate of diarrhea. The answer is that, because of near-continuous exposure, their digestive systems have gradually grown to recognize and tolerate strains of bacteria that other people can’t handle. No one knows how long this immunity takes to develop or how long it holds up, but a study in Nepal found that American adults needed 7 years of local life to adjust, and they lost their tolerance after only a few months back home.

Interestingly, enterprising travelers can use one approach for instant immunity. If you’re worried about E. coli (which is the most common culprit in Mexico), you can buy a vaccine called Dukoral that gives you temporary immunity. To get Dukoral, head to your local pharmacy or check with a travel clinic, which can also identify the gastrointestinal dangers in different parts of the world.

Source of Information : Oreilly - Your Body Missing Manual

Instant Health Checks for Buildings and Bridges

noreply@blogger.com (Science Knowledge) — Tue, 06 Dec 2011 00:08:00 PST

Sensors can detect damage that may be invisible to the naked eye

During 2011’s deadly onslaught of earthquakes, floods and tornadoes, countless buildings had to be evacuated while workers checked to make sure they were stable. The events served as a reminder that most structures are still inspected by a decidedly low-tech method: the naked eye. To speed the process and make it more accurate, investigators are researching electronic skins, evolutionary algorithms and other systems that can monitor the integrity of bridges, buildings, dams and other structures in real time. To automatically detect tiny faults and relay their precise locations, civil engineer Simon Laflamme of the Massachusetts Institute of Technology and his colleagues are devising a “sensing skin”—flexible patches that glue to areas where cracks are likely to occur and continuously monitor them. The formation of a crack would cause a tiny movement in the concrete under a patch, causing a change in the electrical charge stored in the sensing skin, which is made of stretchable plastic mixed with titanium oxide. Every day a computer attached to a collection of patches would send out a current to measure each patch’s charge, a system that Laflamme and his colleagues detail in the Journal of Materials Chemistry

Another engineer is applying a similar concept to bridges. To monitor deterioration inside suspension bridge cables, Raimondo Betti of Columbia University and his collaborators are testing 40 sensors in cables in New York City’s Manhattan Bridge (above). The sensors track temperature, humidity and corrosion rate.

Although these sensors can detect damage that occurs after they have been installed, what about damage a structure had beforehand? Roboticist Hod Lipson of Cornell University and his colleagues have developed a computer model that simulates an intact structure and runs algorithms that evolve this model until it matches data that sensors provide, which can reveal a broader scope of damage.

Others are not yet convinced of these projects’ benefits. “There does not exist, yet, enough research and data that economically support continuous and timely maintenance,” Laflamme says. Another concern might be the yet to be studied long-term performance of the systems, especially in harsh environments—a matter for future research.

Source of Information : Scientific American Magazine

Diet Advice from Your Small Intestine

noreply@blogger.com (Science Knowledge) — Wed, 30 Nov 2011 07:25:00 PST

One of your digestive system’s limitations is that the body parts in charge of picking, identifying, and enjoying what you eat (your brain and your mouth) sit a great distance away from the parts that actually process and absorb your meal (mainly, your small intestine). So it’s no wonder that this system so often slips out of sync, sending you hurtling straight into dietary trouble.
The real problem is that your brain and mouth follow a somewhat outdated ingredient list. They’re always searching for the immediate gratification of sweet, calorie-dense foods. The rest of your digestive system simply processes whatever it gets. In 100,000 years of human evolution, it never occurred to anyone that people might somehow be able to consume vastly more food than they need.

The only antidote to the rampant abuses of modern eating is to simplify your diet with a few common-sense principles. And now that your small intestine has broken your breakfast down into its essential parts—protein, fat, and sugar—it’s easier to pick out these principles, and to separate what your body eats from what it needs. Here’s what your small intestine would ask for if it had a voice:

• Natural, unprocessed foods. Industrial processing—the sort of thing that changes a box of ordinary rice into a package of breakfast cereal— amounts to pre-digestion. It takes responsibility for breaking down foods away from your small intestine, and it can eliminate trace elements of hundreds of different nutrients—all for a product that tastes like flavored packing material.

• Plant-based foods, with small quantities of meat. Unless you’re a weight-training athlete, your body can get all the protein it needs from two servings of meat per day. (That’s a piece of chicken, beef, or fish that’s the size of the palm of your hand, without the fingers.) Dieticians often suggest treating meat as a condiment—in other words, as something you add to flavor a nutrient-rich plate of vegetables.

• A rich variety. Rather than obsess about the nutritional merits of squash versus sweet potatoes, strive to incorporate a range of healthy food into your diet. Highly varied dining offers another benefit: The sheer amount of healthy food tends to crowd out other, less desirable foods.

• More complex carbohydrates, less sugar. Your mouth, stomach, and small intestine eventually break down all carbohydrates into sugar. The more refined the carbohydrate, the faster the conversion, and the quicker you absorb it. This is a problem, because your digestive system is all about pacing (as demonstrated by the careful, one-squirt-ata- time food transmission from your stomach to your small intestine). Heavily refined foods leave your stomach more quickly, which reduces your body’s ability to pace itself and leads to see-sawing levels of blood sugar that your liver must work hard to adjust. But if you fill up with complex carbohydrates like vegetables, whole wheat flour, and brown rice, you’ll have a tankful of food that will fuel you with a slow, steady supply of sugar for hours to come.

• Water. If your food comes premixed with fluid, you need less saliva and gastric juice to create the creamy paste your digestive system expects. And although well-meaning nutritionists sometimes warn heavy drinkers (of water) that they can dilute their gastric acids at mealtime, the effect is minor and has little effect on the average stomach.

Source of Information : Oreilly - Your Body Missing Manual

Clearing the Smoke Marijuana remains tightly controlled, even though its compounds show promise

noreply@blogger.com (Science Knowledge) — Mon, 28 Nov 2011 00:03:00 PST

Preliminary clinical trials show marijuana might be useful for pain, nausea and weight loss in cancer and HIV/AIDS and for muscle spasms in multiple sclerosis. Medical marijuana studies in the U.S. are dwindling fast, however, as funding for research in California—the only state to support research on the whole cannabis plant—comes to an end this year and federal regulations on obtaining marijuana for study remain tight.

In July the Drug Enforcement Administration denied a petition, first filed in 2002 and supported by the American Medical Association, to change marijuana’s current classification. So marijuana remains in the administration’s most tightly controlled category, Schedule I, defined as drugs that “have a high potential for abuse” and “have no currently accepted medical use in treatment in the U.S.” Many medical cannabis proponents see a catch-22 in the U.S.’s marijuana control. One of the DEA’s reasons for keeping marijuana in Schedule I is that the drug does not have enough clinical trials showing its benefits. Yet the classification may limit research by making marijuana difficult for investigators to obtain.

Even as prospects for whole-plant marijuana research dim, those who study isolated compounds from marijuana— which incorporates more than 400 different types of molecules—have an easier time. The drug’s main active chemical, delta 9-tetrahydrocannabinol (THC), is already FDA-approved for nausea and weight loss in cancer and HIV/AIDS patients. The Mayo Clinic is investigating the compound, trade-named Marinol, as a treatment for irritable bowel syndrome. Researchers at Brigham and Women’s Hospital in Boston are studying Marinol for chronic pain.

Compared with smoked or vaporized marijuana, isolated cannabis compounds are more likely to reach federal approval, experts say. Pharmaceutical companies are more likely to develop individual compounds because they are easier to standardize and patent. The results should be similar to inhaled marijuana, says Mahmoud ElSohly, a marijuana chemistry researcher at the University of Mississippi, whose lab grows the nation’s only research-grade marijuana.

Other investigators say a turn away from whole-plant research would shortchange patients because the many compounds in marijuana work together to produce a better effect than any one compound alone. Inhaling plant material may also provide a faster-acting therapy than taking Marinol by mouth. While ElSohly agrees that other marijuana compounds can enhance THC, he thinks just a few chemicals should re-create most of marijuana’s benefits.

Source of Information : Scientific American Magazine

Purposefully Indigestible

noreply@blogger.com (Science Knowledge) — Fri, 25 Nov 2011 06:44:00 PST

Depending on your meal, your small intestine may contain quite a bit of undigested food. (This isn’t the case with the simple breakfast example because it’s short on plant matter and other sources of fiber.) In modest quantities, this undigested food benefits your digestive system and eases the passage of your meal as it scrapes through your narrow intestinal passageways. We call it fiber. One example of indigestible food is cellulose, a compound that helps form the structure of green plants.

In the dieting world, there’s a completely different class of indigestible food substances that masquerade as the sugar and fats our mouths expect, while dodging the absorption step in the small intestine. One example, sucralose (which is known commercially as Splenda), is a subtly modified version of sugar that triggers the sweet taste buds on your tongue, but can’t be broken down by the carbohydrate-processing enzymes in your body. Another example is olestra, an altered fat molecule that has the same mouth feel as fat but passes unhindered through your small intestine. (Eat olestra in great quantities, and you’ll have a significant amount of unneeded matter moving through your system, potentially leading to the abdominal cramping and loose stools mentioned in the package warning label.) These two indigestible foods are examples of food science at its creative best—and potential health concerns.

The key concern for most sugar and fat replacements is not toxic side effects, but the way they allow non-foods with no nutritional value to take up valuable stomach space. Dieters caught up in the excitement of eating without weight gain may forget that their calorie-free potato chips are displacing real foods, and in the process robbing their bodies of the vitamins, minerals, and other nutrients they need.

Source of Information : Oreilly - Your Body Missing Manual

Is It Safe to Drink?

noreply@blogger.com (Science Knowledge) — Mon, 21 Nov 2011 23:58:00 PST

The government may not be doing enough to regulate contaminants in tap water

More than 6,000 chemicals pollute U.S. drinking water, yet the U.S. Environmental Protection Agency has added only one new pollutant to its regulatory roster in the past 15 years. Environmental groups have long raised questions about this track record, and the U.S. Government Accountability Office recently joined the chorus, releasing a report that charges the agency with taking actions that have “impeded... progress in helping assure the public of safe drinking water.”

Among other things, the GAO report says, the EPA relies on flawed data. To determine the level of a particular pollutant in drinking water—which the EPA does before making a regulatory ruling on it—the agency relies on analytic testing methods so insensitive that they cannot identify the contaminants at levels expected to cause health effects. In addition, since 1996 the EPA has been required to make regulatory decisions about five new pollutants each year, ruling on those that might pose the biggest threats to public health. The GAO report asserts that the agency has been ruling only on the “low-hanging fruit”—contaminants for which regulatory decisions are easy rather than those that might be the most dangerous.

“They’re not actually doing anything to protect public health,” says Mae Wu, an attorney at the Natural Resources Defense Council. For its part, the EPA has pledged to review the nation’s drinking-water standards and to add at least 16 new contaminants to the list of those it regulates. This past February the agency reversed a longstanding decision to not regulate the rocket-fuel ingredient perchlorate, making the chemical the first new drinking-water contaminant to be regulated since 1996. In its response to the GAO, the EPA stated that “no action” was necessary to better prioritize the contaminants on which the agency will rule in the future, nor did it acknowledge the need for improvements in data collection. The agency did, however, agree to consider improving its methods for alerting the public when there are drinking- water advisories.

Source of Information : Scientific American Magazine

The Great Absorber

noreply@blogger.com (Science Knowledge) — Wed, 16 Nov 2011 06:41:00 PST

Your small intestine has two important responsibilities. First, it finishes digesting your meal, further breaking down its proteins, fats, and starches into simpler compounds. To perform this task, it gets help from several accessory organs, including your pancreas, liver, and gallbladder. Second, your small intestine absorbs your meal’s final, fully digested nutrients, pulling them out of the pasty digestive solution and passing them directly into your bloodstream, making them available to the rest of your body. The easiest way to understand what’s going on in your small intestine is to consider the different types of food it processes:
• Carbohydrates. Several hours ago, you began to digest your breakfast toast in the relatively easygoing environment of your mouth. Now, deep in your abdomen, the process continues with a new series of more powerful enzymes that shatter the remnants of your toast into simple sugars. Your body secretes these enzymes from your pancreas—a plain looking slab of an organ that squirts digestive juices into your small intestine.

• Proteins. More recently, your stomach started working on the proteins in your eggs and sausage. Your small intestine finishes the job, again with the help of enzymes from your pancreas. The end results are amino acids—fundamental building blocks your body uses to assemble hundreds of thousands of different biological compounds.

• Fats. Your body has to break these down into fatty acids. Once again, the pancreas secretes the enzymes your small intestine needs to do the job. However, before these enzymes can get to work, your body needs a way to break the big, greasy globules of fat into tiny droplets, in much the same way that dish detergent dissolves the oil from last night’s deep-fried chicken. Two organs solve the problem. First, the liver—a multifaceted organ whose main responsibility is filtering blood—creates bile that does the trick. Second, the gallbladder—a kiwi-sized organ that looks like an unremarkable green pouch—stores and concentrates this bile between meals.

Once your body breaks down these nutrients, they seep through your thin intestinal walls, along with various vitamins and minerals. To make this process easier, thin folds lined with tiny hairs cover your small intestine. These details help increase your small intestine’s surface area to promote nutrient absorption.

With the pancreas’s high-powered digestive abilities, you might wonder why it doesn’t eat itself. The trick is that the pancreas releases harmless, inactive enzymes. These enzymes switch themselves on when they meet up with the strong acids in the partly digested food in your intestine.

Source of Information : Oreilly - Your Body Missing Manual

Using Intestines from the Animal Kingdom

noreply@blogger.com (Science Knowledge) — Wed, 09 Nov 2011 18:36:00 PST

Your intestines are quite important, and you’d be ill advised to part with a single foot of the stretchy tubing. However, it just so happens that the resilient tissue that lines your gut lends itself to a host of arts and crafts. Humans have capitalized on this with the help of other animals. In fact, we’re downright notorious in the animal kingdom for putting the intestines of other species to work in a variety of creative ways. Here are some examples:
• Cheese-making. Cow, sheep, and goat guts contain rennet, an important additive in the cheese-making process. Presumably, ancient man discovered this while making cheese in a convenient sack—the stomach of a dead animal.

• Music-playing. For centuries, craftsman fitted violins and other stringed instruments with tough fibers made from animal intestines. Although silk, nylon, and steel are more common today, some top-caliber musicians insist that nothing can match the sound of fresh sheep gut.

• Food. Natural sausage casings (the thin, plasticky substance that wraps your breakfast sausage) use animal gut from a pig, cow, or sheep.

• Sex. The world’s oldest known condoms (dating back to about 1640) were made from sheep intestines. They were quite expensive, which probably accounts for the roaring trade in washed, second-hand condoms that prevailed at the time.

Source of Information : Oreilly - Your Body Missing Manual