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Scientific American is the essential guide to the most awe-inspiring advances in science and technology, explaining how they change our understanding of the. Scientific American (ISSN ), Volume , Number 1, January , published monthly by Scientific American, a division of Nature. Scientific American (ISSN ), Volume , Number 3, March , published monthly by Scientific American, a division of Nature.
The processes tice anything unusualshe will age at the normal rate. Powell, there is a photograph of string government are theorists, including Leonard Susskind, at Stanford University. Feynman, Rob- ert B. Leighton and Matthew Sands. This is an elementary introduction to thomas m. I cannot imagine that the laguna woods, calif. Misner, Kip S.
Eventually one linked sensors that track indoor loca. The same goes for certain bovines. The system most likely is a decade cal Reserve. And unlike GPS. If the initiator advances in the tion using Wi-Fi or Bluetooth. Air Force od. It turns out jammers and the landscape itself can from the consumer market but has that European bison operate by majority rule. Anyone can initiate a movement. The process is relatively straightforward: Naval Control Observatory.
Wi-Fi hotspot. Missile Range in New Mexico. Locata networks also have helped bison makes a move. By outfitting those individuals likely to be three separate satellites triangulate a accuracy to everyday consumers. The behavior satellite carries four atomic clocks that other connected devices. Ideally Locata transceivers would The findings could help wildlife managers reduce ting satellite in medium Earth orbit to be integrated into all cellular towers.
Three such readings from bringing centimeter-level location raid crops. The study was location by measuring the time it takes warfare environments. In fact. If they would rather slake their have attempted to fill in holes with of unmanned aircraft safety systems. Two transmit antennas are shown above. Goldman by layering in an independent net. In essence. Ecologist port or urban canyon amid skyscrap.
For Ramos. A lot of novice researchers can go them at their field sites and been acknowl. January I was once feet up of tree to climb? Edited excerpts follow. I help When not assisting with scientific studies. I also went out with some herpe- rather than on branches. Getting the rope in tologists in India to find king cobras in the place is usually the hardest part.
Costa Rica. Tree Climb. Many of those trips were organized by biologists. When much deeper connection to nature.. Lucky for me. What is the most challenging aspect of climbing trees? Have you collected data yourself?
I also work with scientists doing outreach: Why do scientists call you? For most trees. He has my job is that I get to travel with them to taught close to 1. Now a master climb- ing instructor.
It will same for dwindling numbers volume of traffic. The added preying foxes. For more details. Its inventors suggest the bot could regulations permit. California retailers are prohibited from selling showerheads. As of January 1. The company is offering cash to Hits become a fixture at construction sites. With few participants. The participants justified this psy- chological detachment by the amount of money they made.
When people put money before mental health. Alden Cass. We strive for meaning within our jobs and take criticism of our labors personally. Not so for senior investment bankers. The inspiration for the nomenclature fol- lowed a series of in-depth interviews conducted over nearly two years with six senior investment bankers in London.
University of London. But it is notable. The minimization of self could serve as a coping mechanism. They dissociate their sense of self so severely from their work that researchers have coined a new term for the phenomenon: The frontoparietal network.
This risk for schizophrenia to see if the scans can These fingerprintlike profiles identified par. Gazzaniga of the University of California.
The study authors do not ining fingerprints or strands of DNA. Institute for Psychiatric Research. But the find- ing feature with near-perfect accuracy. A recent study shows that to identify people. Finn an estimate of the strength of connections involved in focusing our attention.
Kline was then created for each subject based on than others. Maybe someone else can have isms. And I think this approach has already Many of the same hormones that operate in metabolic hunger had an influence on obesity treatment.
He has tried various pothalamus. At age Lowe says. Once these cells begin to in the past several years have research. But only out the body. In cheap and plentiful. Whenever people eat more calories than er]. The result is an intense feeling of pleasure. Yu recently pre- spond to the neurochemical. The researchers also found that drugs that prevent resist eating those foods once they are around.
Yi-Hao Yu. In contrast. A few studies have documented tory the challenge for human beings was getting enough to eat to lower levels of hunger-stimulating ghrelin and increased levels avoid starvation. Known as bar. For much of our evolutionary past. In contemporary society—replete with inexpensive. A ues. University School of Medicine. In a series of studies between and This intricate web of neural ribbons has in sugar and fat—possibly because of changes in the amount of mostly been studied in the context of addictive drugs and.
Back then. These people may. As soon as such a dish cal Center in St. Merely seeing with drugs. Charles Cohen. Douglas Knopper told me. You know. If we pony up To find out why. In our hearts. So until someone figures out how to crack for the ads to arrive. These can lead to some murky territory. Some compa- nies that operate ad blockers even accept money from large advertisers. The sites for leading U. The economics to the retailer data charges. If the micropayments were cheap and easy.
They create a technology arms race. What then? As Kurt Huang. ITV present a dark screen and a simple declaration to the effect ScientificAmerican. Suddenly the popularity of ad-blocking software has reached micropayment company Beenz. Last summer Wired. But these tactics treat the public as the enemy. Illustration by Viktor Koen January Individuals— and. In vertebrates. Without it. The ability to figure out where we are and where we need to Over the past few decades researchers have gained a deep go is key to survival.
Recent ed to those of other animals. Our ability to pilot a car or airplane—or even to walk through city streets—has been completely transformed by the invention of the Global Positioning System GPS. How did we navigate. When these neural tracts malfunction. Moser are professors in psychology and neuroscience at the Norwegian University of Science and Technology in Trondheim. Mammal Initial path Mammals have evolved still more Based on his observations. Tolman did ory functions.
This allows them to find tire maze to be able to plan the best route. In he reported that neurons there fired when not have the concepts or tools to test whether an internal map a rat in a box spent time at a certain location—thus. Mammals have found an even more elaborate solution that uses internalized mental maps.
On higher rungs of the evolutionary chain. He had observed rats take Return trip zags traversed on an outbound journey. Acceptance came slowly. These cognitive maps of the physical world.
Animals store maps did more than help animals to find memories of past journeys and use them their way. These networks of neurons make up mental try of the outer world. This idea. In learning to run a maze. Equipped rats seemed to suggest that animals find with a mere neurons. In the s progress in cells collectively formed a map of locations in the box. Ranck of most every study before ours. We were eager to investigate. Many head- only when.
After expanding it to a certain size. James B. Ranck and Taube had discovered But unlike a place cell. To our surprise. At the end of the s. In most parts of the cortex. At each vertex. The most striking property of these cells. In the next module down. At their inputs in any manner that could easily be understood the dorsal part. Our attention where it is positioned in relation then turned to the only neural pathway that had been spared by our intervention: The size of the hexagons increased in a series of steps—or vironment dashed that speculation.
In collaboration with Menno Witter. We expected the work to confirm that form internal maps of the this circuit was important to the proper functioning of the place cells. But these had used for our place cell studies.
In the lowest module. In the module at the top of the cal navigation-related computations from other hippocampal entorhinal cortex. Neuroscientists have subsequently whenever the animal approached a wall identified cells that work together to create such maps.
These border cells fired etry of the outer world first emerged around The firing rates of these neurons increased in proportion to the speed of movement. A key development came in By integrating inputs from the medial and lateral location in the same room. John Kubie and the late vironment also fire at analogous positions on the map for another January This information could then relation to the walls of an enclosure.
In the authors late how far the animal was from a discovered grid cells that let an animal measure its location in its environment—say. As the animal moves about. In conjunction with cell firing head-direction cells.
The pattern one room to the next. At the top of the entorhinal cortex. Other Specialized Cells Recently Discovered. At the bottom. Cross section of the Entorhinal cortex CA3 and CA1 that produce a mental map optimized hippocampal region yellow for planning future journeys inset. The sequence of cells that fire as spatial navigation. The grids formed in the medial entorhinal the animal moves northeast in one room of the cage repeats when cortex that measure distance and direction do not change from the rat goes in that same direction in the other room.
From the standpoint of evolution.. We are now researching how these smaller ates and deploys them. If invertebrates use them. Experiments performed in other labs— to help unlock the neural codes the brain uses for navigation. This coupling of place with memory recalls a strategy for memorization invented by ancient Greeks and Romans.
The spatial representation system has maps merge to form an integrated map of a given area. Grid Cells. A separate volved in navigation arose early in the evolution of mammals grid pattern was then superimposed on the new alley. We know that the brain has an internal map.
Nobel lecture. When the memory is later retrieved. The illness causes brain cells moser-lecture. Edvard I. In rodents. The multiple cell types that have sageway. December 7. The study showed that. Decem- ber 7. Even become one of the best-understood circuits of the mammalian these experiments are oversimplified because the enclosures cortex. Moser et al. The tendency to The Matrix in Your Head. Place Cells and Memory. July The light curve did suggest that J was a young.
It was there that my colleague Eric Mamajek of the University of Rochester showed me something that sent us on a quest to find the first ringed planet beyond our solar system.
We now call it J for short. M uch astronomy takes place in the offices and observatories where scientists work.
He studies planets around other stars and produces optical coronagraphs to help take pictures of them. Data from other years showed no such tion in the sky. Along the way. Mamajek could not to be seen directly. If confirmed. It and the of an impression. In the odd event did not make much J To guess the ages of their candi. In his spare time.
It is not by coincidence that one of the best bars in Tucson. But if you want to find the most exciting theories. But after he saw it in What could cause across their stars as seen from Earth. Further studies of system some times larger than and archival data. Whatever it was. So we dismissed them. For two years we sought to image the planet while looking But why did we think it was a ring system? The most strik. Could it be a belt of dust orbiting close to the went looking for the planet.
If we were right. The flickering brightness suggests Time hidden structure. Could the flickering be a coincidence caused by a star.
A brief boost in brightness can be caused by stellar flares. But the wildly fluctuating light curve 56 days. The speed of the elliptical geometry—much like the familiar ring system of Sat- brightness fluctuations suggested that the eclipsing object was urn.
We quickly ruled out such obvious culprits as be seen at all timescales—the eclipses lasted 56 days. One by one. Was this a binary system. These speeds hinted that the giant eclipsing object had large ming was not located on Earth. But J is very young for be a giant star. JULY Soon after that discussion we began working together to ing feature in the light curve was the level of detail that could solve the mystery. In the end. This long duration meant that the object was some million kilometers in size.
Though challenging. As a ring passes across the star. Even so. To prove it. If that planet transits across the face of its star and if its ring system is precisely aligned with our line of sight. We also enlisted looked at the wrong time. In Same ring but these cases. In this ideal scenario. We found nothing. April 15 and-fro tugging of that unseen orbiting world. Examining the slopes within the light curve of J Sure enough. This model suggests the presence of a large gap in the rings.
Using this additional would extract information about the makeup and three-dimen. For months our team developed computer models that try. May 1 May 15 June 1 Jb. Our model suggests that the system and how its ring system has evolved over time. They consist of mers have never seen before: Counting up all these points in the light curve. To understand why. Our calculations suggest that the moon takes Those particles. It is Mars. The solid contains a large gap. Ring systems like that of Jb dwarf it in size and are likely to be common throughout the galaxy.
They record a century of ing the planet from above. And if the moon pos. Sculpting by Exomoons? They are looking for the dip Jb would be set like a small jewel amid the glare of scat. When that happens. Transiting rings. Meanwhile we are still hunting for definitive frictional heating as they passed through. You might think that it is a sec- The emerging picture of this exotic.
Eclipses by Circumsecondary and Circumplanetary Disks. The largest telescopes and most sensitive instru.
Flying in from interstellar space. Instead that evi. Right now our best guess is that it will happen sometime in sesses an atmosphere. Most excitingly. Some of to digitize and upload all the data stored on these fragile glass those waves would break at the great gap produced by the larg.
Article No. Off in one wing. To date. Just a few meters away from this bustling building are the Harvard Plate Stacks. Proving the existence of ous coverage from around the world. With the data If the moon orbits slightly out of the ring plane.
March Newborn giant planets are thought to give searching for exomoons. When the This system offers astronomers much more. My colleagues and I are already scouring new intensive searches for exomoons. If our solar astronomers with small telescopes can follow the brightness system is any guide.
Wreathed These photographic plates are now being scanned by the with fans of debris produced by collisions. The Search for Life on Faraway Moons. Kenworthy and E. Better Than Earth. A large moon around such a planet from Jb. August Now that star.
We have determined that J appears on about of est clump between two rings. Discovery of an Extrasolar Ring hypothetical. February Smithsonian Center for Astrophysics.
Her parents had arranged her mar- riage to a man she had never seen who lived in Kolsur. In many of the re. Environmental Studies. Although the World Health Now the ever expanding use of groundwater wells—people Organization says arsenic concentrations are dangerous above need water to drink.
Scientists have recently been trying something new: At least million people in Asia are drinking arsenic-contam. Scientists had this water has changed the courses of underground streams..
It ments. An elder brother had lost a foot to rot. Then she met his family. But when Gita laid eyes on her husband. Gita decided that she and her hus. But death also lay underground. On her wedding night. They were sunk in an attempt to ly underground. Gita Paul felt doomed. Arranged marriages to strangers are common in the region.
Arsenic-laced ground. But so far the subterranean flow changes and The scientists and the villagers were right. The university is now working to set up More than 18 million of these small wells have been dug across a research institution in his name—the DC Research Founda- India alone.
They spent all the money they had to relo. It pours out of countless tube wells. Nepal and Bangladesh. Many people in the village were ill. But reliable mapping is hard. Cambodia and Vietnam. But people there were the underground landscape in an attempt to pinpoint safer plac- also dying. In South Asia—con- water has been found in at least 30 countries. But many of the worst- to brain damage.
Pumping out the illness was not airborne—it was in the water. The lesions on his body are symptoms of the poison. Drill a bit far- gan drinking groundwater as an alternative to being poisoned by ther, and the water is usually potable.
But drilling deeper wells bacteria-infested surface water, often stagnant and unprotected takes more time and money, requiring sturdier materials that from sewage or agricultural runoff.
In India launched a many impoverished villagers cannot afford. Widespread ignorance and UNICEF, to drill holes into the earth and sink more than a mil- institutional apathy stymie efforts to educate people about the lion simple wells.
More programs followed. There seemed little risks. Seemingly simple solutions, such as harvesting rainwater other choice. India had almost no infrastructure for storing, dis- or treating water on the spot, prove too complex for the illiterate tributing or filtering water—a situation that remains today, ex- and are easily misunderstood.
Harvesting efforts break down as cept in the largest cities. Filtering water The tube wells were hailed as an inexpensive and lifesaving though sand-filled buckets is often seen as an onerous and time- solution. More permanent solutions, such as den plots. Groundwater solved another acute problem: After the giant mountains were formed water contaminated with pathogens, the groundwater is seen as through tectonic collisions, arsenic-laden pyrite minerals in their the lesser of two evils.
Tasteless, colorless and through the water, it underwent chemical reactions to combine odorless, it was long a favorite tool for assassins. It is toxic to with oxygen and iron or other heavy metals, forming granules most life-forms, even at very low doses. Over millennia the muddy depos-. At one point, this ple covering almost , square kilometers of land.
That means there are a lot more possibil- By the natural order of things, most of that arsenic should ities for finding arsenic. In con- arsenic per liter Kolkata tact with underground water, arsenic of groundwater Sumatra can break free in concentrations high Very likely enough—at least 10 micrograms per liter Somewhat likely of water—to harm human health.
Chem- Less likely ical reactions leading to the breakouts Unlikely can be triggered in two ways. High-pH, Poor estimation or basic, water circulating through soils can free the element, as can oxygen- depleted water moving through soils rich Poisoned Soil Is a Global Issue Researchers at the Swiss Federal Institute of Aquatic Science and Technology Eawag created a world map of in organic carbons.
By analyzing water arsenic risk based on arsenic-releasing soil conditions. The combination of oxygen-rich soil and high-pH water and soil conditions in various parts of the makes parts of Argentina and Chile likely hotspots. Soils with abundant organic carbon but low oxygen levels, world, scientists try to predict the places common in river delta regions such as northern India and Bangladesh, as well as the site basin, raise risk most likely to be in danger.
site data are not completely reliable, however. For instance, Hanoi in Vietnam pulls water from an arsenic-free aquifer Tainted well orange that used to flow away from the city. The water pressure dropped lower than pressure in the dirty aquifer, so the Clean aquifer Underground Arsenic-laden Increased pumping changes pressure Newly flow began to reverse, and tainted sands water flow arrows aquifer sands gradient and reverses water flow contaminated zone water moved closer to the city.
In this case, the bacteria promote the ygen-rich soils, where water with an alkaline high pH is circulat- chemical reactions using catalyzing enzymes to bust up iron ox- ing, such as in arid regions of Argentina or the southwestern U. So if one were to take a handful The water triggers a chemical reaction that breaks apart oxidized of soil from an area with arsenic-free groundwater—say, in North iron and other metals coating soil particles.
That frees any arse- Carolina—and bury it in Bangladesh, it would release arsenic. Fer- The second scenario—reductive arsenic release—takes place in tilizers, which are used heavily in India, can prolong the process. These conditions It can be mitigated by salinity, particularly sulfides, which will are typical in deltas, floodplains and river basins, where surface also bond with arsenic to create precipitates.
But that only holds soil is often new enough to still be infused with bacteria. These for as long as the oxygen remains low. So if aquifers are depleted and re-. Doherty Earth Observatory.
He had gone ty map in and plan a newer version incorporating the latest into the China study assuming the model would follow alkaline studies and more details soon.
That gave us a lot of confidence that this predictive he recalculated using these parameters. Recharging aquifers is also common in India. Because the models are based on save money and time by narrowing the number of tube wells surface conditions and recent knowledge about water flow.
They published the first draft of their global risk-probabili. Such tists have begun to seek shortcuts. The China risk model set its grid sizes at to build a China model after tests on some After the water is mixed with several reagents. They say such methods can help governments There are limits.
So some scien. When confirmed. The color of the strip after about 10 minutes gives a ballpark result: Somehow we need to show policy makers that we can help solve real problems. But the field kit offers only a blunt test that can detect contamination to a certain level.
Jadavpur University who studies how the chemical moves through aquifers. Beyond that or for more de- tail. One study found that only two of 13 plants from sev- eral manufacturers maintained arsenic levels below the Indian standard. Chakraborti and others have shown that the simple. By the time the study was published in In the Bengali village of Jaynagar.
Simple treatment plants to remove the chemical. So to But the water runs only a few hours a day. The black. The low-lying aquifers. There are cracks and holes. Hundreds of arsenic-removal plants. This is already happening in India. None reliably met the WHO standard. It is in the rice. September The best most can manage ably still bound to other elements in the soil and only gradually is to eat nutritious food and stop ingesting the poison.
International Growth Center. And when where. Even where fields are located next to lakes or rivers. Geen et al. Then I know the family free aquifer that used to flow away from the city.
Chelation therapy. Mushtaque and R. Chakraborti has even found it in bottled sodas and vials of sterile water used by hospitals.
The two are also studying how socioeco- nomic factors such as income or caste identity might keep people from using safe wells shared by other castes or those with less money. Follow-up research also suggests that villagers who pay for testing are more likely to heed the results and switch to safer though less convenient wells. This chromosomal damage done. Even when no water is need. They are not as accurate as lab tests but give imme. It is one to listen. There is no Water from the tainted aquifer.
This movement is cur. His study found that arsenic is cally in extreme cases of metal poisoning. Srivas being freed by underground chemical reactions. He has a teenage son who helps In India. In Bangladesh. Part C. Calloused lesions cov- water from the safe layer. That flow pushed will be okay. He has organized inter- national conferences and led teams of doctors. October A Year Study Report.
Genes provide cells with the instructions for manufacturing proteins. It codes for a hor- mone called ecdysone. Kirk tells me. As it happens. Kirk is a billionaire geek who runs his offices out of West Palm Beach. After the new exoskeleton is ready. Once molting is nearing completion. Doctors would like to deliver copies of working genes to people to treat a variety of hereditary ills. A logical solution to the problem of having proteins made in The scientists at the company decided to take advantage of undesirable places and amounts would be to combine a thera.
He built his fortune on conventional medica- tions that can be taken as a pill. Insects do not just sort of molt. Pa- a switch to control molting. The gene that interests Kirk serves as the master switch for all this activity. But the molting process.
The ge. But gene therapy has had a troubled histo. As ecdysone surges through the insect. The switch does not allow this group of genes to act velopment of malignant tumors. These tight when turned off—molting does not happen in the absence problems can lead to unwanted side effects—including the de.
Drug entire molecule Drug molecule to self-destruct molecule nisms. Cell-specific promoters are swatch. Trouble is. Kill tions. Each copy of an inserted The RNA switch folds into es of genetic material that cause genes gene gets its own switch. Cancer immunotherapies. Or at least that is the idea. Eventually the ability to deliv- er several switch-controlled genes— each one able to be dialed up or down as needed—should make gene thera- py safe and effective enough that it can become part of mainstream medi- cine.
No ecdysone. Pre- liminary tests in humans suggest that Switch is on Kill switch is turned off the switch approach could work as intended. The addition of these molecular gatekeepers further reduces Switch off the chances of unwanted side effects occurring in parts of the body that had Gene cannot In the absence of direct RNA a switch-controlling not been targeted for treatment. In an unex- pected emergency. So far it has been studied Only the presence of a particular The addition of a custom- drug.
In addi- tion. All genes. IL can cause a sharp drop in blood pressure. But to date. As anticipated. Because the switch can be activated only by the ly occurring RNA molecules called ribozymes. If a cytokine storm starts bozymes consist of RNA.
In the blood. Doctors inject one ing the worst of the damage. Kirk acknowledges that they might have chosen to itor and adjust the fight against tumors. Results from two safety studies conducted at several medical Cytokines trigger a wide range of physiological reactions— centers and totaling fewer than 40 patients suggest that the an- from opening up blood vessels so that immune cells can rush to swer is yes. The M. The IL treatment shrank can easily lead to organ failure and death.
His approach features small natural- latter a boost. In immunotherapy. Although no one was cured. Here is where the switch technology could multiforme. Investigators believe test their approach on something less potent than the IL that they may not need to treat all the malignant lesions in gene—where the slightest misstep could prove fatal. And yet. Now a biotech firm has reworked ecdysone into a much needed safety switch for gene therapy.
But he says. IL is the holy grail of uptick in cytokine levels and other cancer-fighting activity. For various rea- stream.
In one of the studies. In a feature useful for switches. The War on Cancer Is Evolving.
Scott in mRNA self-destruct. Someday many of the pills that doctors give patients may be used to switch on various transferred genes rounding cellular machinery would then break the mRNA at precisely the right place and time in the body instead of flood- apart and cause the entire process of building a protein to ing every organ and tissue with the powerful pharmaceutical grind to a halt.
With a touch of gene therapy safe and effective whimsy. Structure— of mRNA intact. In- turn off protein synthesis when desired. Take the pill. As with ecdysone. Breaker and his colleagues at ing side effects. The Power of Riboswitches. Combining switch-enabled gene therapy mRNA should result in the same outcome—production of a with other anticancer regimens may also bear tremendous fruit. The trick was to link stead new gene treatments will allow patients to churn out a mol- the ribozyme to an additional molecule called an aptamer.
By Mulligan and his colleagues were regularly equip. Because the gene switches and their respective activators will allow him to adjust one able to be dialed up or the levels of IL and IL independently. The third part of this ex- ing the rest of the mRNA molecule to appear defective. Already M. If inserting new genes into our bodies in the s was Genetic Engi- neering 1. When the drug Activity Relationships. The sensors can be designed with great specificity.
The processes tice anything unusualshe will age at the normal rate. Powell, there is a photograph of string government are theorists, including Leonard Susskind, at Stanford University. Feynman, Rob- ert B. Leighton and Matthew Sands. This is an elementary introduction to thomas m. I cannot imagine that the laguna woods, calif. Misner, Kip S. Thorne and John September dom? Its much the existence of free will that ignores the more advanced, but again, I suspect the following evidence against it: Some peo- motive for its inclusion was homage.
Berkeley, Calif. The review and approval pro- Stanley Becker of the books that I use most often where cesses for obtaining research funding from via e-mail they could be seen. Feynmans books may the federal government are not friendly to have been intended for a freshman class, new ideas and approaches. If you are have demonstrated high levels of skill and our preferences constitute our will, and confused about a subject in physics, the creativity should be given more freedom to therefore if we act on the basis of those pref- first place to go is Feynman.