sniff 5.sni.99987 Louis J. Sheehan, Esquire

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Louis J. Sheehan, Esquire . Women smell better than men, and it's not just the perfume. As is the case for many gender differences, hormones appear to be behind the general advantage women have when it comes to their ability to detect odors.http://louis4j4sheehan4esquire.wordpress.com

In a series of trials, a total of 36 volunteers tried to detect either a cherry-almond or a lemon-orange smell generated by gradually decreasing concentrations of specific chemical compounds. In initial smell-threshold tests, all participants exhibited comparable abilities to detect the odors.http://louis4j4sheehan4esquire.wordpress.com

During tests 3 months later, however, women of reproductive age showed vast improvements in their ability to detect progressively weaker odors after only a handful of exposures to those smells, say neuroscientist Pamela Dalton of the Monell Chemical Senses Center in Philadelphia and her colleagues. In contrast, men failed to become more smell-sensitive, even after many exposures to the odors. The same was true for women past menopause and 8-to-10-year-old girls and boys, the scientists report in an upcoming Nature Neuroscience.

These results raise the possibility that female sex hormones act in ways that boost sensitivity to familiar odors, according to Dalton's group. Having a nose for smells may confer reproduction-related benefits, such as helping women forge close relationships with children and mates and the ability to detect poisons in food while pregnant, the researchers theorize.

bruno 3.bru.010010 Louis J. Sheehan, Esquire

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Louis J. Sheehan, Esquire . The 16th-century Italian philosopher (and former Catholic priest) Giordano Bruno was burned at the stake for a stubborn adherence to his then unorthodox beliefs—including the ideas that the universe is infinite and that other solar systems exist. Art historian Ingrid Rowland vividly recounts Bruno’s journey through a quickly changing Reformation-era Europe, where he managed to stir up controversy at every turn. http://louis7j7sheehan7esquire.wordpress.com Having a habit of calling schoolmasters “asses,” Bruno was jailed in Geneva for slandering his professor after publishing a broadsheet listing 20 mistakes the man had made in a single lecture. http://louis7j7sheehan7esquire.wordpress.com

Bruno’s adventures in free thought ended when the Roman Inquisition declared him “an impenitent, pertinacious, and obstinate heretic,” to which he characteristically replied, “You may be more afraid to bring that sentence against me than I am to accept it.” In 1600 the inquisitors stripped Bruno naked, bound his tongue, and burned him alive. At least his universe survived. Louis J. Sheehan, Esquire .

experiments 44.exp.8 Louis J. Sheehan, Esquire

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Louis J. Sheehan, Esquire . Whatever troubles climate change might bring to the world's other species, rising carbon dioxide in the atmosphere could be the best thing yet for poison ivy. http://louis9j9sheehan.blog.com

An outdoor experiment mimicking the carbon dioxide rise predicted for this century found that poison ivy vines grew more than twice as much per year as they did in unaltered air, says Jacqueline E. Mohan, now of the Marine Biological Laboratory in Woods Hole, Mass. That growth streak is nearly five times the increase reported for some tree species in other analyses.

More bad news: The jolt of carbon dioxide also boosted the most-toxic forms of poison ivy's rash-raising oil, Mohan and her colleagues report in the June 13 Proceedings of the National Academy of Sciences. http://louis9j9sheehan.blog.com

"It's a sobering example that rising carbon dioxide can favor pests and weeds, those plants we'd least like to see succeed," comments climate-change ecologist Bruce Hungate of Northern Arizona University in Flagstaff.

People burning fossil fuels release carbon dioxide into the atmosphere. As the atmosphere gains carbon dioxide and other so-called greenhouse gases, it traps more of the sun's heat.

Biologists have wondered whether this carbon boost might work as aerial fertilizer for plants. Earlier lab experiments found plants growing exuberantly with extra carbon dioxide, but these tests provided abundant water and nutrients.

For more-realistic tests, researchers have set up treetop-high pipes that blow either regular air or extra carbon dioxide over landscape patches in various ecosystems around the world. For 6 years, Mohan and her colleagues monitored poison ivy and the other plants growing within circles of such pipes in a pine forest monitored by researchers of Duke University in Durham, N.C.

The poison ivy vines thrived with about 50 percent extra carbon dioxide, showing extra photosynthesis and more-efficient water use.

These vines produced the same concentration of the toxic oil urushiol as the plain-air vines did. However, for the poison ivy receiving extra carbon dioxide, about 20 percent of the oil was in chemically unsaturated forms, whereas the plain-air ivy produced 15 percent unsaturated urushiol. The unsaturated forms are more likely to provoke painful skin reactions in people.

Other studies have suggested that vines may be big winners in a high–carbon dioxide future, says Mohan. Vines don't spend much of their carbon harvest on trunks or other supports, so the carbon windfall can go directly into new leaves, which collect yet more carbon and sunlight.

An increased abundance of vines, which can choke out trees, could change forest dynamics, Mohan says.

Forest honeysuckle vines increase their growth in air that's high in carbon dioxide, says Rich Norby, who directs a pipe-circle experiment at Oak Ridge (Tenn.) National Laboratory. However, he predicts that even poison ivy's gangbuster growth will eventually hit some limit, such as available sunlight.

The pipe-circle experiments can't mimic all the factors influencing plants in real forests. Mohan protected her experimental poison ivy plants from white-tailed deer and other browsing animals, notes plant physiologist Hendrik Poorter of Utrecht University in the Netherlands. Yet plants growing in abundant carbon dioxide typically have low protein content, so Poorter speculates that animals might actually eat more of them to get adequate nutrition.

Bigger, more-toxic poison ivy is a serious concern, says Paul Beggs of Macquarie University in Australia. It's another factor to add to his tally of the extra misery that climate change might bring to people with allergies. For example, certain pollen counts are likely to go up, so allergy seasons could drag on longer, he says.

Mohan had never developed a rash from poison ivy before she started the study. "I get it now," she says.

wild horses 88.hor.2 Louis J. Sheehan, Esquire

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Madeleine Pickens, wife of the eccentric billionaire tycoon T. Boone Pickens, wants to ride to the rescue of a beleaguered national icon. The wild horses that have been an emblem of the wide-open American West for centuries more recently became a major headache for the federal government, which routinely removes some of the horses from 1o Western states to prevent overpopulation and protect grazing land. But as the Bureau of Land Management’s (BLM) holding facilities grew crowded, federal officials gingerly announced that they were considering a euthanasia program to cull the herds at their facilities and contain costs.http://louissheehan.bravejournal.com/



Pickens, a racehorse breeder and lifelong animal lover, said she was horrified when she learned about the problem. “There’s got to be a way to bypass [the BLM] — why does it have to be Washington to solve the problem?” said Pickens, who, along with her husband, airlifted 800 cats and dogs stranded by Hurricane Katrina in New Orleans and brought them to California for adoption [Washington Post]. Pickens approached BLM officials and suggested an alternative: She would buy 1 million acres of rangeland somewhere in the West, and convert it into a permanent retirement home for the roughly 30,000 homeless and unwanted horses.http://louissheehan.bravejournal.com

Pickens says she envisions a refuge that’s open to the public, where tourists could sleep in log cabins or tepees to get a taste of the frontier experience. “You shouldn’t be coming to this country to see Mickey Mouse and Donald Duck,” she said. “We are more than that. We are a country that was formed on horseback and we should enjoy it, not slaughter it” [Dallas Morning News].http://louissheehan.bravejournal.com



The wild horses and burros would be sterilized, Pickens said, so they wouldn’t contribute further to the overpopulation problem, and additional animals rounded up by the BLM could gradually be brought in to the refuge. About 33,000 horses still make their homes on the range, but the BLM hopes to bring that number down to about 27,000. Tom Gorey, a bureau spokesman, said the agency welcomes her offer. “Right now we couldn’t be more pleased with her interest and we hope that materializes so that we can get many of these horses out of holding,” he said. Louis J. Sheehan, Esquire.

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Louis J. Sheehan, Esquire. Around 5,000 years ago, a lone hunter trekking through Europe's Tyrolean Alps ate his final two meals. First, he munched on wild cereals, goat meat, and a few flowering plants. Later, the man partook of red deer meat and possibly more cereals. Then he died in a rocky basin, where his frozen, naturally mummified body was discovered in 1991.http://Louis-j-sheehan-esquire.us

The ancient culinary sendoff of the so-called Tyrolean Iceman has emerged from an analysis of food remains in his colon and intestines. Researchers directed by Franco Rollo of the University of Camerino in Italy extracted DNA and tested it for similarities to DNA from a variety of modern plant and animal species.http://Louis-j-sheehan-esquire.us

Other genetic evidence identified pollen residue in the hunter's colon. This material, probably unintentionally ingested by breathing or by drinking water, indicates that he made his last journey through a heavily forested area, Rollo and his colleagues report in an upcoming Proceedings of the National Academy of Sciences.

The scientists theorize that rival hunters killed the Iceman; he has an arrowhead imbedded in his left shoulder.http://Louis-j-sheehan-esquire.us

maya-ii Louis J. Sheehan, Esquire

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From a modern chemist’s perspective, the structure of DNA in our genes is rather mundane. The molecule has a well-known importance for life, but chemists often see only a uniform double helix with almost no functional behavior on its own. It may come as a surprise, then, to learn that this molecule is the basis of a truly rich and strange research area that bridges synthetic chemistry, enzymology, structural nanotechnology and computer science.

Using this new science, we have constructed molecular versions of logic gates that can operate in water solution. Our goal in building these DNA-based computing modules is to develop nanoscopic machines that could exist in living organisms, sensing conditions and making decisions based on what they sense, then responding with actions such as releasing medicine or killing specific cells.

We have demonstrated some of the abilities of our DNA gates by building automata that play perfect games of tic-tac-toe. The human player adds solutions of DNA strands to signal his or her moves, and the DNA computer responds by lighting up the square it has chosen to take next. Any mistake by the human player will be punished with defeat. Although game playing is a long way from our ultimate goals, it is a good test of how readily the elementary molecular computing modules can be combined in plug-and-play fashion to perform complicated functions, just as the silicon-based gates in modern computers can be wired up to form the complex logic circuits that carry out everything that computers do for us today.

Dissolved Doctors
Near the end of 1997 two of us (Stojanovic and Stefanovic) decided to combine our individual skills in chemistry and computer science and work on a project together. As friends from elementary school in Belgrade, Serbia, we happened to be having dinner, and, encouraged by some wine, we considered several topics, including bioinformatics and various existing ways of using DNA to perform computations. We decided to develop a new method to employ molecules to compute and make decisions on their own.

We planned to borrow an approach from electrical engineering and create a set of molecular modules, or primitives, that would perform elementary computing operations. In electrical engineering the computing primitives are called logic gates, with intuitive names such as AND, OR and NOT. These gates receive incoming electrical signals that represent the 0s and 1s of binary code and perform logic operations to produce outgoing electrical signals. For instance, an AND gate produces an output 1 only if its two incoming inputs are both 1. Modern-day computers have hundreds of millions of such logic gates connected into very complex circuits, like elaborate structures built out of just a few kinds of Lego blocks. Similarly, we hoped that our molecular modules could be mixed together into increasingly complex computing devices. Louis J. Sheehan, Esquire

We did not aim, however, to compete with silicon-based computers. Instead, because Stojanovic had just finished a brief stint with a pharmaceutical company, we settled on developing a system that could be useful for making “smart” therapeutic agents, such as drugs that could sense and analyze conditions in a patient and respond appropriately with no human intervention after being injected. For example, one such smart agent might monitor glucose levels in the blood and decide when to release insulin. Thus, our molecular logic gates had to be biocompatible. http://louis-j-sheehan.net

Such molecular modules could have innumerable functions. For instance, in diseases such as leukemia, numerous subpopulations of white blood cells in the immune system display characteristic markers on their cell surfaces, depending on the cells’ lineage and their stage of development. Present-day therapies using antibodies eliminate large numbers of these subpopulations at once, because they target only one of the surface markers. Such indiscriminate attacks can suppress the patient’s immune system by wiping out too many healthy cells, leading to serious complications and even death. Molecular modules capable of working together to sense and analyze multiple markers—including performing logical operations such as “markers A and either B or C are present, but D is absent”—might be able to select the specific subpopulations of cells that are diseased and growing out of control and then eliminate only those cells.

Another application of our modules could be in the analysis of DNA, looking for a large array of possible genetic mutations or identifying one of a wide variety of microbiological pathogens. Our most advanced tic-tac-toe-playing automaton combines 32 different short DNA sequences (oligonucleotides). That many logic gate inputs could analyze four billion possible combinations of oligonucleotides and partition them into thousands of patterns, each pattern being characteristic of certain pathogens or genotypes.

Molecular Logic
Researchers reported logic gates based on synthetic molecules as long ago as the early 1990s. In 1993, for instance, A. Prasanna de Silva and his collaborators at Queen’s University Belfast made AND gates out of small organic molecules that would fluoresce only if both hydrogen ions (from acid) and sodium ions were bound to them. In 1997 J. Fraser Stoddart, now at Northwestern University, and his co-workers made “exclusive OR” (XOR) gates, in which the molecules fluoresced in the presence of either, but not both, of the inputs (in this case, hydrogen ions and molecules called amines). These examples, however, were not biocompatible, because they required concentrations of acid and other compounds that would harm living cells.

In the mid-1990s other researchers exploited DNA’s ability to store information in its sequence of bases—the molecules conventionally abbreviated as A, T, G and C, which pair up to form the rungs connecting the two strands of the famous double-helix structure. Their techniques, however, were very different from the kind of system we envisaged, namely, one in which molecular logic gates floating in solution would process inputs and outputs in a fashion very analogous to the workings of silicon logic gates. Nevertheless, DNA clearly had a lot of potential for biocompatible computation, and a couple of other advances gave us the tools to invent our own brand of DNA logic gates.

First, in 1995 Gerald F. Joyce of the Scripps Research Institute in La Jolla, Calif., developed a method for producing enzymes made out of single strands of DNA that cut other pieces of single-stranded DNA into two segments. These so-called deoxyribozymes have two short arms that will bind only to another stretch of DNA that has the correct complementary sequence of bases, so they are very specific about which substrate DNA strands they will cleave.

Special dye molecules attached to each end of the substrate strands enable laboratory workers to monitor the cleaving process. At one end of the substrate, the dye molecule is a “quencher,” which prevents the fluorescent marker dye at the other end from fluorescing as long as the strand remains intact, keeping the quencher close enough to be effective. After the strand is cut, its two pieces move apart and the marker dye molecule can fluoresce unhindered. As the work of the DNA enzymes progresses, cutting more and more strands, the solution gradually lights up with the marker dye’s fluorescent color.

The other key advance came soon after our initial planning, when Ronald R. Breaker of Yale University reported a way to integrate a deoxyribozyme with molecular groups acting as recognition modules. These modules work like sensors that either activate or inhibit their attached DNA enzyme when the correct input molecule is bound to them. Breaker even combined two such modules in a construct that could serve as an AND gate with two small input molecules. Very intriguingly, his group has found that such two-sensor constructs have been used by natural riboswitches—molecules made of RNA used by bacteria to control which of their genes actively produce proteins [see “The Power of Riboswitches,” by Jeffrey E. Barrick and Ronald R. Breaker; Scientific American, January 2007].

We saw that we could build our logic gates out of DNA enzymes integrated with controlling sensor modules designed to recognize short DNA strands having specific base sequences. The DNA strands would thus act as inputs to the logic gates (an input of 1 if the strand is present; 0 if it is absent), and the gates’ enzymes would output “1” by cleaving other DNA strands in the solution. With DNA serving as both inputs and outputs, our gates could in principle be chained together to form complex circuits. Like wires in electrical circuits, the base sequences of the sensors and the enzymes would control which gates’ outputs “connected” to which inputs, even as all the gates sloshed around independently in a test tube.

After some less than successful attempts using other designs, we settled on DNA structures known as stem-loops for our recognition modules. Sanjay Tyagi and Fred Kramer, both at the Public Health Research Institute in Newark, N.J., had reported that stem-loops switch between two shapes, or conformations. In the closed conformation the DNA strand making up the stem-loop folds onto itself, and the two ends zip together, forming a stem along with a loop of unzipped DNA, like the outline of a lollipop. An input DNA strand consisting of the sequence of bases complementary to the loop will bind to it, but in forming a stretch of the familiar double helix it pries the stem apart—the double-helical DNA cannot form a tight enough curve to maintain the closed loop.

Depending on how we attach a stem-loop to a DNA enzyme, opening the loop may either activate or inhibit the enzyme’s activity. If one of the enzyme’s two substrate-matching arms serves as one side of the stem, then the closed stem will block the enzyme’s activity. We call this structure a sensor or a YES gate because adding the input strand (say, “input X”) for the stem-loop controller opens the stem, exposing the enzyme’s substrate-matching region and allowing it to function. The enzyme’s output (specific cleaved strands of DNA) in essence says, “YES, input X is present.”

Adding a second stem-loop with a different loop sequence (Y) on the other of the enzyme’s two arms yields an AND gate. Only if input X AND input Y bind to it can the enzyme function and cleave DNA.

We make an inhibitory controller—one that will deactivate the enzyme when the correct input binds to the loop—by plugging a stem-loop sequence into the “back” of the enzyme. Now when the stem is closed, the enzyme is intact and produces output. The relevant input strand will open the stem-loop and deform the enzyme enough to inactivate it. Of course, this inactivation will not remove output strands already produced by the gate, so in isolation this NOT gate does not function as conveniently as an electronic NOT gate. But the NOT unit comes into its own when combined with the AND gate structure. The resulting gate, which we call AND-AND-NOT, produces output only if inputs X AND Y AND NOT Z are present. That function, also known as an INHIBIT gate, turned out to be very useful for our tic-tac-toe automata.

The most important aspect of our system is that it is highly modular. We can use hundreds and theoretically millions of different base sequences for the inputs, and we can also change the sequences of the output strands. We could even switch the underlying enzyme to be a ligase, one that joins together short strands to produce longer ones. Indeed, Andrew D. Ellington’s group at the University of Texas at Austin has studied ligase-based switches extensively.
The functioning of the gates is also autonomous. That is, once we trigger a computation by adding the input to the solution, no more human intervention is required. In essence, DNA molecules make the decisions on their own, based on whatever inputs they receive. http://louis-j-sheehan.net

Our gates do have some significant differences, however, from the silicon-based logic in electrical circuits. First, we cannot reset our gates. Once an input strand is bound to a stem-loop controller, it tends to remain there for the rest of the computation. Nor can the cleaved oligonucleotide output strands be reassembled. Our ultimate biomedical goals do not require a gate-reset function, but it would be useful for potential molecular robotics applications (involving moving parts). We are exploring the use of ligase enzymes to reassemble output strands. Louis J. Sheehan, Esquire

Second, electronic gates have a threshold voltage at which their switching happens, and their outputs are tied to specific voltages so that they cannot linger at an intermediate voltage. Thus, the 0s and 1s are well defined, and the logic is truly digital. Solutions of our gates, in contrast, change in continuous fashion between the inactive and the fully active forms depending on how many inputs we add to the fluid. This behavior would be important if we were attempting to build the molecular equivalent of a personal computer, but it does not matter for many biomedical applications.

DNA Plays Tic-Tac-Toe
With a general approach to constructing molecular logic gates in our hands, we looked for an objective test of their ability to compute. We wanted to apply our logic gates in a situation in which everyone would immediately see that the molecules were making decisions. A traditional test for a new computer system is to make it play a game of strategy. The rules of a game provide a challenge with a straightforward measure of success: the system will either be able to play the game or not. Game-playing ability is intimately connected with general computational ability.

We chose the classic children’s game of tic-tac-toe for our demonstration. In this game, played on a 3 x 3 grid, two players try to put three marks in a row while blocking the opponent from doing the same. Tic-tac-toe is one of the simplest two-player games of perfect information, meaning that a player knows everything that there is to know about the state of the game at each move (unlike, for instance, most card games, in which rivals’ cards are unknown). Tic-tac-toe will always end in a draw if both parties play well, but our device will exploit any mistake the opponent makes.

The game is simple enough that we can encode all decision making into logic operations that examine only the opponent’s moves. That is, when you are using a fixed strategy, even if you remember only what your opponent’s moves have been, you can work out what your own past moves must have been and therefore what the current board position is and what your strategy dictates as your next move. We condensed that chain of reasoning down to a network of logic gates that takes the opponent’s moves as inputs and produces your next move as the output. In 2002 we set out to build just such a network out of DNA logic gates, a tic-tac-toe-playing automaton that we christened MAYA (molecular array of YES and AND-AND-NOT gates).

MAYA consists of nine wells corresponding to the squares of the tic-tac-toe grid. Each well contains its own precisely defined set of DNA logic gates in solution. The enzymes of these gates are all designed to cleave the same substrate DNA strand, which is also in all the wells, but they require magnesium ions to function. Thus, adding magnesium ions stirs MAYA into action. Because the enzymes in the central well have no stem-loop controllers on them, they start cleaving the substrate immediately. The fluorescence from the central well increases, signaling that MAYA has taken the central square as the opening move.

The human (let’s call him Harry) has eight input strands (one for each of the eight remaining squares) for inputting his moves. The base sequences of these strands are complementary to the sequences on the stem-loops that control MAYA’s DNA gates. To move in square 4, for instance, Harry adds input 4 to all nine of MAYA’s wells. MAYA signals its move in response by turning on the fluorescence in another of the wells.

As the game progresses, each well contains input strands representing all Harry’s moves, and the combination of gates in each well processes those inputs. After every move, one of the wells contains a gate that the last input triggers in combination with the previous inputs. That well lights up to indicate a move by MAYA.

To simplify MAYA’s programming, we restricted Harry’s first move to be either the upper left corner (square 1) or the left side (square 4). Those two moves are representative of all the moves that Harry might make in response to MAYA’s opening move in the center because the board is symmetric. If he moved somewhere else, the board could be rotated to make it a move in either square 1 or 4. With that restriction, the strategy we chose for MAYA allows 19 different possible games to be played. In one of the games, Harry plays perfectly and the game ends in a draw. In the remaining 18 games, MAYA exploits his mistakes and wins.

To work out all the required gates for the automaton, we considered every move in all 19 games and determined which gates would produce the desired move. The hardest part was matching the strategy requirements with our logic-gate technology. Although our gates are designed to output DNA strands that could in principle serve as inputs to other gates, for MAYA we chose to avoid relying on that feature and the extra complications it might engender. Altogether we took less than three months to design and develop MAYA and fully test all 19 games in the laboratory.

MAYA-II
Not content with MAYA’s limitations, we built an unrestricted version, MAYA-II. We also made MAYA-II more user-friendly, displaying both players’ moves in two different fluorescent colors. The automaton still goes first and claims the middle square, but Harry the human can then take any of the remaining eight squares. MAYA-II plays four times as many possible games as MAYA, winning 72 of them and drawing four.

We wrote a computer program (for a standard silicon-based computer) to determine an appropriate arrangement of logic gates. The resulting design calls for 128 different logic gates, 96 for deciding and signaling the automaton’s moves using red fluorescence and 32 to highlight Harry’s moves in green fluorescence.

The sheer size of this automaton made building and testing MAYA-II an enormous challenge. One of us (Macdonald) led the project and trained several high school students to test automata, mostly during summers and on Saturdays. The students checked all 76 games multiple times. They had to make changes in MAYA-II’s design to deal with several problems (and then recheck all the games after each tweak).

Our chief concern going into the project was that some sequences might bind in unintended places. Our computer-modeling tools were not advanced enough to be able to predict such difficulties. In fact, spurious binding was relatively rare. Instead the more serious problem turned out to be individual gates cleaving their substrates at different rates. We (or, rather, our students) had to adjust concentrations and structures to correct for this variability. We also quickly discovered that some gates acted differently within a mixture than they did on their own, necessitating other redesigns. Finally, after three consecutive summers and many Saturdays, through some changes of inputs and many small adjustments of gate sequences and concentrations, our team had a system in which we could clearly distinguish active and inactive gates in all wells, for all the games, reproducibly.

Implications
Integrating more than 100 molecular logic components in a single system represented a substantial milestone. In the jargon of electronics, MAYA-II is the first “medium-scale integrated molecular circuit.” Our work on a device of such complexity let us refine our deoxyribozyme logic gates as plug-and-play computing primitives. New efforts in our laboratories now proceed more smoothly with existing components, and we can design gates that usually work immediately without needing any fine-tuning.

We could integrate our method with other molecular computing approaches developed recently. For example, Erik Winfree’s group at the California Institute of Technology came up with impressive “strand displacement cascades,” which could be used to analyze mixtures of oligonucleotides in a similar fashion. In this scheme, strands of DNA combine, joining and displacing one another mostly without the need for any catalysts analogous to the DNA enzymes of our gates. Winfree’s system has been demonstrated with a cascade of five units. In comparison, our present system suffers from becoming prohibitively slow if three layers of gates are combined. MAYA-II, for all its complexity, functions as a single layer of gates and takes around 15 minutes to carry out a move.

For our decision-making molecules, we are now very confident about putting many gates together, and tasks representing fresh challenges beckon. We hope one day to report a mixture of molecules that can be taught a strategy by playing example games with them or by introducing some selection to eliminate the gates that encode losing strategies. We might then develop automata that we can train to recognize cancer cells. Louis J. Sheehan, Esquire

But perhaps the most important next step of our program is to incorporate new primitives to carry out more functions, such as sensing and moving (or “actuating”). These are automata that would take action based on the presence of a given input. Our plug-and-play system would then be moving well beyond “play” and would be ready for some real work.

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Scientists may have found the world’s oldest intact rocks in a 10-square-kilometer patch of bedrock on the eastern shore of Canada’s Hudson Bay। Geochemical analyses suggest the rocks are around 4.28 billion years old, which would mean they solidified less than 300 million years after Earth formed. http://Louis-J-sheehan.info

If the dating holds true, the new oldest rocks could be a trove of information about geological processes during Earth’s earliest history, the researchers report in the Sept. 26 Science.

The rocks have the same chemical composition as volcanic deposits, says Jonathan O’Neil, a geochemist at McGill University in Montreal and coauthor of the new study. He and his colleagues measured the ratio of two rare chemical isotopes — neodymium-142 and samarium-146 — to come up with an age estimate for the rocks. The previous oldest known rocks formed about 4.03 billion years ago and were found in what is now Canada’s Northwest Territories.

Scientists have discovered zircon crystals that are about 4.4 billion years old. However, those individual mineral grains, which are now part of much-younger sedimentary rocks found in Western Australia, originated in rocks that eroded long ago (SN: 8/2/08, p. 13). The rocks from Hudson Bay, which have been heated and squeezed deep within Earth at least once since they formed, may be the world’s oldest rocks that remain intact, O’Neil and his colleagues speculate.

Geochemical analyses of the Hudson Bay rocks are the first to show an unusually low proportion of neodymium-142 to another isotope, neodymium-144, says O’Neil। Scientists have long been looking for this signal, which indicates that the outer mantle — the layer just below Earth’s crust — had, before 4.1 billion years ago, begun to segregate into zones having different chemical compositions. http://Louis-J-sheehan.info

“I’m very excited about this work,” says Vickie C. Bennett, a geochemist at Australian National University in Canberra. “Now we’re beginning to see into the first 500 million years of Earth’s history,” she adds. Scientists can now start to assess how the geophysical processes early in Earth’s history have influenced those occurring today, she notes.

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SciNoFi Blog Roundup - Fringe Edition

To paraphrase the Hold Steady, we like to stay positive. At Science Not Fiction, staying positive means that we don’t debunk (or nerdgas.) If the sonic screwdriver solves the problem, then by all means whip it out.

That being said, this show Fringe is seriously stretching us to the limit.

Fringe Gets Fast Aging and Frozen Optics Wrong [Popular Mechanics]

Fringe “violates basic tenets of biology, chemistry and physics without any explanation.” [Polite Dissent]

Now that we’ve gotten that off our chest, here are few other links to help lighten the mood:

You say Obama? I say Adama for President. [LA Times]

H.P Lovecraft as the Whitman’s Sampler copy writer [McSweeney’s]

Future Farms to Have Giant Livestock [Modern Mechanix]

September 24th, 2008 Tags: bad science, Fringe
by Sam Lowry in Biotech, TV | 2 Comments »

Eureka: Out With A Bang

Last night’s midseason finale of Eureka tied up a number of loose ends, and set up a number of new plot points for the second half of the third season, set to air sometime in 2009. (Incidentally, last minute struggles with the script for this episode were responsible for Eureka co-creater Jamie Paglia having to sprint through the San Diego Convention Center to make it on time to DISCOVER’s Comic-Con panel on the Science Behind Science Fiction.) One of the things that Sheriff Carter finds himself contending with is a “nanoparticle syntactic foam” that goes from foam to something harder than concrete in a few seconds—the ideal substance for sealing off the abandoned underground facility that has been featured throughout the season, but not something you’d want to spill on yourself.

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September 24th, 2008 Tags: Eureka, syntactic foam
by Stephen Cass in Future Tech, TV | No Comments »

Terminator: At Least Cyborgs Enunciate

Ever since the first Terminator movie in 1984, Terminator cyborgs have had the ability to duplicate the voice of any given human they hear, an ability deployed again in last night episode of Terminator: The Sarah Connor Chronicles, when our plucky band of heroes has its cell phones intercepted. It’s not so far fetched — pretty much this exact scenario has been worrying real security researchers for some time.

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September 23rd, 2008 Tags: accessibility, Security, speech synthesis, Terminator, universal translator
by Stephen Cass in Cyborgs, TV | 2 Comments »

Artificial Blood: Coming To A Hospital Near You?

The theme of HBO’s new series, TrueBlood, is based on a Japanese scientist’s invention of synthetic blood. The breakthrough allows vampires to “come out of the coffin” and progress from freakish villains to fellow citizens. (Just stop into a local TrueBlood bank for a snack, and humans are off the menu.)

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September 22nd, 2008 Tags: Artificial blood, artificial tissue, Terminator, TrueBlood
by Stephen Cass in Biotech, TV | 3 Comments »

5 Greatest Space Operas (And No, Foundation Isn’t One Of Them)

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Space Opera is one of my favorite sub-genres of science fiction, and in recent years has gained a new lease of life (I recommend reading The New Space Opera anthology for good snapshot of the current state of affairs). Like all definitions, saying what exactly is and isn’t space opera can be a highly subjective exercise, but for me, works of space opera all try for a certain grand sweep: the canvas is broad, often involving a good chunk of at least one galaxy. The themes are big–space opera is where entire space-faring civilizations can collide–and awesome technologies are frequently brought into play.

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September 19th, 2008 Tags: Babylon 5, Battlestar Galactica, Blake's 7, Doctor Who, Foundation, Known Space, Lensmen, Star Wars, Stargate, The Culture
by Stephen Cass in Space Opera | 19 Comments »

Dreaming of Carnivorous Plants and Life-Saving Bacteria

The sci-fi blog io9 recently announced the winners of their Mad Science Contest, in which they invited their readers to dream up useful or just really sweet ways to use synthetic biology. The two winners were:

Vijaykumar Meli, who laid out a plan for a bacterium that would improve the nitrogen fixation of rice plants, thereby decreasing pollution from fertilizer run-off and improving yield, which could save plenty of lives in the developing world. Meli says the technique could be accomplished using current technology, including parts from the BioBricks collection of standard biological parts.

Elliott Gresswell, who stumbled upon the fictitious lab notebooks of researchers who inadvertently create walking, nanotech-caused-gray-goo-living carnivorous trees, illustrated here by comic book artist Kevin O’Neill. (These fantastic monsters wouldn’t be too out of place with the space-faring fungus hats that Jaron Lanier has imagined in synthetic biology’s future.)

Hats off to the winners. (In Gresswell’s case, perhaps that would be, “Heads off”…)

September 18th, 2008 by Amos Kenigsberg in Biotech, Comics | No Comments »

Eureka: The Death of Stars

On Tuesday’s nights Eureka, a miniature sun was accidently born in the skies above the town, wreaking destruction. The solution? To shoot iron into the sunlet’s core.

This is in fact not far off how some real stars die: iron poisoning. Read the rest of this entry »

September 18th, 2008 Tags: Eureka, stellar evolution
by Stephen Cass in Astronomy, Space, TV, physics | No Comments »

Fringe: The Ultimate Test Tube Baby

Fringe, J.J. Abrams’ (of Lost and Alias fame) latest show, last night featured the unintended fall out from an attempt to grow humans in tanks. Since the goal of the original attempt was to produce fully grown soldiers, bypassing the normal wait time of 9 months plus 18 years, some liberties were taken with growth hormones in order to accelerate aging. Thus fall out, such as a baby that goes from conception to death of old age within a few hours.

Growing human beings outside the confines of a real uterus–ectogenesis–has been a staple of science-fiction since at least Aldus Huxley’s Brave New World: it was a critical element in The Matrix, and even featured in a recent Doctor Who episode. It’s also been a staple of real science for some time: in 1996, Japanese researchers were able to keep goat fetuses alive and developing for 3 weeks in their artificial womb. In 2002, researchers at Cornell were able to keep human embryos alive and developing for several days, after which the experiments were terminated to stay within embryonic research ethics rules.

This real research is driven by the desire to help childless people, or dangerously premature babies, and not, say, a hankering for a super-soldier production line. But if the day comes when we can produce a child with just a smear of genetic material and a machine, then we will have to do some deep thinking. On the one hand, this kind of technology could allow us to colonize distant star systems (instead of trying to keep humans alive for hundreds of years of interstellar travel, send a robot and some DNA), while on the other it could lead to the creation of an entirely new underclass of humanity, a la the “tanks” of Space: Above and Beyond.

September 17th, 2008 Tags: Artificial Womb, Doctor Who, ectogenesis, Fringe, The Matrix
by Stephen Cass in Biology, Biotech, TV | 4 Comments »

Terminator: Better Pool Hustling Through Technology

In last night’s episode of Terminator: The Sarah Connor Chronicles, Cameron accepts the invitation (and wager) of a couple of security guards to play a game of pool. Having gotten close enough to scan their security badges, Cameron then proceeds to smoke them at the game, thanks to a little known pool mode in her Point-Of-View display, which, thus far, has tended to show more in the way of helpful information about the caliber of weapon she is using or instructions like TERMINATE.

In the real world, enter Deep Green. Read the rest of this entry »

September 16th, 2008 Tags: Deep Green, pool, Terminator
by Stephen Cass in Robots, TV | 1 Comment »

Stargate Atlantis: Gene Therapy

On Friday night’s episode of Stargate Atlantis, one of the characters had to go undercover in order to convince a faction of the show’s resident villians, the Wraith, to accept a gene therapy. The therapy would eliminate the Wraith’s need to feed on human beings, something which has become a bone of contention between the Wraith and other residents of their galaxy.

Gene therapy works by rewriting a patient’s genetic code, an impossibility with conventional medicines, and could be used to combat diseases such as hemophilia, Parkinsons, and cancer. It’s a beautifully simple idea in concept, but the real world scientists that are working to make it a common-place reality are finding the execution to be a tough problem.

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September 15th, 2008 Tags: Gene Therapy, Stargate Atlantis
by Stephen Cass in Biotech, Genetics, TV | 2 Comments »

Anathem Review

Okay, here’s the one thing that some fans of Neal Stephenson will want to know: yes, it has a ‘proper’ ending. (Although Stephenson defends his authorial choices vigorously, a criticism leveled at some of his books by some readers is that they don’t end, so much as just stop.) While there are still some interesting questions left by the end of Anathem, the characters do see resolution to their stories. (Also, the hockey jerseys now make perfect sense.)

So, that settled, what’s the beginning and middle of the book like? Awesome. Despite its length at 960 pages, the fast pacing of the book is reminiscent of Stephenson’s earlier, shorter, Snow Crash and The Diamond Age. However, he also takes the time and room to delve into subjects ranging from orbital mechanics to Plato’s Theory of Forms. The book revolves around the adventures of a young scholar called Erasmas, who has lived most of his life within the confines of a millennia-old order mostly devoted to theoretical research. When an enigmatic and unexpected arrival settles into orbit around his world, Erasmas’ life is turned upside down.

The book’s release is well timed, coinciding with the activation of the big daddy of particle accelerators, the Large Hadron Collider. The Large Hadron Collider is part of a quest to understand just how arbitrary are the laws of physics–a question that becomes significant within Anathem.

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September 12th, 2008 Tags: Anathem, LHC, Neal Stephenson, physics
by Stephen Cass in Books, physics | No Comments »

Stargate: Moving on From Atlantis

Stargate Solutions interviewed Joe Mallozzi, showrunner for the recently cancelled Stargate Atlantis, where he talks about the reaction of the cast to the news and his thoughts on the plans to continue the Stargate franchise.

September 11th, 2008 Tags: Stargate Atlantis, Stargate SG-1, Stargate Universe
by Stephen Cass in TV | No Comments »

Eureka: The Fine Art of Dumpster Diving

Last night on Eureka, Sherriff Carter was faced with a bumbling superhero who had constructed his gear from discarded pieces of technology thrown out by the town’s scientists. In this, our wannabe superhero was participating in the ultimate expression of the fine old art of dumpster diving.

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September 10th, 2008 Tags: dumpster diving, Eureka, recycling
by Stephen Cass in Security, TV | No Comments »

Terminator: DIY Tech Support

The new season of Terminator: The Sarah Connor Chronicles kicked off into high gear last night, promising some great TV to come. The episode picked up seconds after the last season left off, when Cameron–a terminator reprogrammed and sent back from the future to protect John Connor, leader-of-the-human-race-in-waiting–became the victim of a car bomb.

A damaged Cameron finds herself in need of some significant hardware and software repairs: unfortunately, it’ll be years before any terminator technical support facilities are built. Cameron must fix herself. In the real world, it’s exactly this problem that researchers are actively struggling with–how to create computers that can realize they’re malfunctioning and restore themselves to working order.

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September 9th, 2008 Tags: Autonomous Computing, Joshua Bongard, Self-Repair, Terminator
by Stephen Cass in Robots, TV | 1 Comment »

Dear Russell Davies: Our Plan to Fix Torchwood

The release of the Torchwood Series 2 DVD gave us the opportunity to watch (in some cases watch for the first time) every episode of the second season.

And the verdict? In the immortal words of Ed Grimley, “totally decent, I must say.” John Barrowman still rocks.

With that out of the way, I’ll add that the show is also showing troubling signs of flaming out after the upcoming mini-series। Series Two had at least one genuinely terrible episode (”From Out of the Rain”) and a few marginal ones (”Something Borrowed,” “To The Last Man”). http://louisejesheehan.blogspot.com

Unlike Doctor Who, Torchwood doesn’t have a multi-decade reserve of goodwill and nostalgia to fall back on। Unlike Buffy, Captain Jack isn’t a teenager whose adolescent angst can be mined for a season’s worth of new story arcs. http://louisejesheehan.blogspot.com

Here are five things we’d like to see more (and less) of in the Series 3 mini-series that would improve the prospects for the show to live on.

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Lost in The Snow
Former Olympic hockey player Eric LeMarque was snowboarding alone in the Sierra Nevada in 2003 when thick fog settled around him, limiting his vision to 10 feet. Soon he was lost in the snowy wilderness with no food and a dead cell phone. He wandered through 15-foot snowdrifts in freezing temperatures for seven days before National Guard searchers found him.

When exposed to bitter cold, your body shivers, and this involuntary movement creates heat the same way exercise does. If you stay in the cold and your body temperature continues to drop, shivering will stop when the muscles no longer have enough energy to move, says David Richard, a professor of biology at Susquehanna University in Pennsylvania. He teaches the course “Exercise and Extreme Physiology” and is an authority on the processes that sustain life under extreme conditions—and on what happens when the human body is exposed to more than it can withstand.

After prolonged exposure to intense cold, Richard says, your body’s chemical reactions begin to slow until they generate too little energy for your muscles to work. By carefully regulating blood flow, your body will protect your key organs while preserving your extremities—at least for a while. In the cold, blood is generally directed to the core of the body and flows only intermittently to the extremities to bring oxygen to cells there. After prolonged exposure to cold, blood travels only to the most essential parts—your brain and heart. As severe hypothermia sets in, these organs may be the only ones left functioning.

In a 2000 paper in The Lancet, a team of Norwegian doctors described resuscitating a woman who had been trapped in icy water for 40 minutes and whose core temperature had dropped to 57 degrees. This is very unusual; most people do not survive a core temperature below 70 degrees, Richard says. Still, upon finding a victim, rescue workers make no assumptions (“They’re not dead until they’re warm and dead,” the saying goes.) You may be breathing so imperceptibly that you look dead, but you might survive if an alert emergency worker warms and resuscitates you.

Frostbite occurs when the temperature in your tissues falls to one or two degrees below freezing. As the water in your tissues turns to ice, salts in body fluids and cells become more concentrated, interfering with proteins so much that the cells die. At the same time, the sharp edges of microscopic ice crystals can tear cell membranes. Don’t rub your frostbitten skin: The force of rubbing can shred already-damaged areas.

Falling Out of a Plane
In 1942 a Soviet pilot named I. M. Chisov plunged 22,000 feet without a parachute after bailing out of his Ilyushin 4 bomber. German pilots had attacked Chisov’s plane, and he didn’t open his chute because he was afraid it would allow his attackers to find him. He landed on a snow-covered slope and rolled downhill, badly hurt and unconscious—but alive.

According to aero­dynamics experts, a skydiver without a chute reaches a terminal velocity of about 120 miles per hour after dropping roughly 500 feet. That actually isn’t any faster than the speed you’d reach if you fell from a moderately tall building. “But it’s not falling that kills you; it’s the landing,” Richard says: The abrupt pressure of an impact is likely to break open blood vessels such as your aorta, damage internal organs, and shatter your bones.

The worst thing to hit is a hard surface that brings you to a halt almost instantly. If you land on snow (like Chisov) or hit something that gives way, such as a skylight (as happened to U.S. Air Force Sergeant Alan Magee, who survived a 20,000-foot drop into a French train station in 1943), you will suffer less damage. In such a situation, it is the ability of the bones of your skull and spine to withstand the impact that can potentially preserve your life, according to a report conducted by the Federal Aviation Administration.

Struck by Lightning
Roy Cleveland Sullivan, a forest ranger in Virginia, was hit by lightning seven times in his 71 years. The lifetime odds of being struck by lightning are higher than you might think—about 1 in 5,000—but it still takes bad luck (and a dangerous lifestyle) to be hit more than once.

About 80 percent of people who are struck are not killed. When lightning strikes, less than 1 percent of the bolt’s current flows through your body, according to a recent study in the Journal of Electrostatics. The rest travels over the surface of your skin, which has a lower resistance to electricity. Lightning bolts, which typically pack a 100-million-volt wallop but are only about as wide as a pencil, may burn your skin or leave feather­like markings called Lichtenberg figures. These form where electric current or the resulting shock wave in the body bursts capillaries in your skin. The burns are not usually severe, however.

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Your biggest worry is dying because your heart stops beating, says Michael Cherington, former director of the Lightning Data Center in Colorado. Current from the bolt may interfere with the impulses that drive your heartbeat. In a 1998 paper, Cherington presented evidence that during the heart’s normal cycle of contracting and relaxing, there is a small window of time when the chambers are filling with blood and the heart is especially vulnerable to electrical disruption. If you are unlucky enough to be struck during this window, death may be much more likely.

If you live, you will probably have damage to your nervous system, as 70 percent of lightning-strike survivors do. “On an MRI, it can look like a stroke,” Cherington says, making lightning strikes difficult to diagnose. (People sometimes black out and don’t realize they were hit.) According to a National Oceanographic and Atmospheric Administration report, you might wind up with bleeding and swelling in your brain, which kills neurons, or suffer other types of nerve damage, leading to seizures or partial paralysis. Short-term memory loss and personality changes may affect you. Finally, you might contract cataracts, as the current and heat of a strike can turn proteins in the lens of your eye opaque.

Adrift at Sea
For 76 days in 1982, Steven Callahan floated 1,800 miles alone at sea in a five-foot life raft after his boat, the Napoleon Solo, sank in the Atlantic. (He made it nearly to Guadeloupe and was rescued by passing fishermen.) Callahan, a naval architect and experienced sailor, survived by catching fish with a makeshift spear and drinking from his raft’s solar stills—inflatable plastic tents that captured one pint of evaporated freshwater from seawater each day.http://louis-j-sheehaN.NET

Dehydration will be a big worry. The length of time you can survive without any water varies; in a hot desert you won’t last as long as you will in a cool, humid forest, according to David Richard. As your body’s moisture dwindles, he explains, your blood thickens so much with salts and clotting proteins that if you accidentally nicked yourself with your fishing spear, you might not even bleed. Your heart strains to generate enough force to pump the gluey fluid, and your blood coagulates easily, paving the way for a stroke or heart attack.

As your kidneys toil to rid your body of salt, your urine darkens. If you don’t find a source of fresh water, rising levels of sodium and potassium wreak havoc on your muscle and nerve cells: Their proteins fall to fragments, and cell membranes leak, Richard says. Pacemaker cells in your heart soon malfunction, sending it into irregular rhythms. Delirium and then unconsciousness set in as brain cells deteriorate. If you succumb to the temptation to drink seawater, that just makes things worse. Seawater is so loaded with salts that your body wastes more water in the urine in an effort to excrete them than it gains in the first place.

Trapped in The Desert
Italian runner Mauro Prosperi got more than he bargained for during the 1994 Marathon des Sables, a weeklong, 145-mile race across the Sahara. A ferocious sandstorm knocked him far off course, leaving him stranded. Prosperi managed to capture a few bats to sustain himself for the nine days he wandered through the bleak landscape, where peak temperatures above 120 degrees Fahrenheit are not unusual. Eventually a group of Tuareg nomads found him and brought him on camelback to an Algerian village.

In the desert, the effects of intense heat compound the threat of dehydration, Richard says. Your heart rate will speed up as your body warms, generally about 10 beats per minute per degree, but your heart has limits. Normally, veins that deliver blood to the heart fill its chambers between contractions. As body temperature increases, though, your heart may contract so frequently that there is not enough time for the chambers to fill between beats, and less blood leaves your heart with each beat. When the heart is already near its maximum due to extreme heat, it cannot pump any faster, making physical activity impossible. Pretty soon you can hardly move at all—not a good situation when you’re stranded without water.

Sitting still in a sauna, you could survive much higher temperatures. In Finland, competitors actually vie to see who can stay the longest in a 230-degree F sauna (winners typically last about 12 minutes). At temperatures much above that, the structures of cell membranes and proteins crumble and the body’s cells become a gooey mess: Think of a soft-boiled egg.

Exposed to a Vacuum
Engineer James C. LeBlanc climbed into a vacuum chamber at NASA’s Johnson Space Center in 1965 for a routine test of a spacesuit. His suit leaked, and for 14 harrowing seconds he was exposed to a near vacuum. LeBlanc later said that he could feel water boiling off his tongue. He then passed out, but technicians and engineers quickly repressurized the chamber; LeBlanc survived with no permanent damage.

Medical researchers at NASA estimate it is possible to revive someone exposed to a vacuum for as long as 30 seconds. Air will be sucked out of your lungs immediately, and trying to hold your breath will be futile against the pressure. In a vacuum the gases and liquids in the body expand rapidly, animal studies show, but your skin and blood vessels maintain enough pressure on your body and its fluids that you will not instantly explode—no matter what you’ve seen in Hollywood films. According to NASA’s analysis, your tissues will swell slowly as water boils away and gases like nitrogen come out of solution, pushing against the membranes of your cells, stretching them and damaging your organs.http://louis-j-sheehaN.NET

If you are fully exposed in outer space, the intense ultraviolet radiation from the unfiltered sun will give you a nasty sunburn on one side. In a vacuum, heat is not lost easily, however, so even though the temperature in deep space is –454 degrees F, you will not freeze immediately. Much sooner—after about 15 seconds—your oxygen-deprived brain will shut down. At that point you will black out, and you will probably die in another minute or two.

Wasklewicz

Researchers have developed a way to use laser-based surveying instruments to create detailed images of ancient etchings on stone. The new technique, which provides far more information than photographs do, could enable archaeologists to quickly catalog the ancient rock art, or petroglyphs, at sites that are geologically unstable or vulnerable to theft or vandalism.

Wasklewicz

The prototype equipment uses a green laser beam that scans back and forth to generate three-dimensional maps of objects and terrain, says Thad Wasklewicz of the University of Memphis in Tennessee. Those maps, which can be compiled in just a few minutes, span a 40° field of view and contain up to 1 million data points—each of which is accurate to within 6 millimeters.

Ancient artists created petroglyphs by scraping away a dark, mineral-rich coating called desert varnish (SN: 1/3/04, p. 14: Available to subscribers at http://www.sciencenews.org/articles/20040103/note15.asp) to expose underlying light-colored material. The intensity of laser light that reflects off the varnish is different from that which bounces back from exposed rock. After field data have been collected, analysts can digitally assign a different shade of color to each intensity level of reflected light and thereby create high-resolution, false-color images of the art.

Wasklewicz and his colleagues field-tested their technique at a site near Little Lake, Calif., where some petroglyphs date back as long as 14,000 years ago. With their equipment, the researchers generated large-scale maps of the ancient lava flows, as well as detailed images of art on individual rocks. In some cases, the laser scans picked up the faint traces of ancient petroglyphs that couldn't be seen with the naked eye because they were obscured by a fresh coat of desert varnish, says Wasklewicz.http://www.soulcast.com/Louis_J_Sheehan_Esquire_1

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capacity

In southern Asia, where an estimated 75 million children qualify as malnourished, lack of food may only be part of the problem. A prospective study in rural Pakistan finds that mothers who became depressed shortly before or after giving birth had babies far more likely to experience stunted growth and bouts of diarrhea than were babies with psychologically healthy mothers.

Maternal depression critically contributes to high rates of malnutrition and failure to thrive among infants in this part of the world, conclude psychologist Atif Rahman of the University of Manchester in England and his colleagues. Most people living in southern Asia now have access to adequate food supplies, the researchers note.

In the new study, maternal depression exhibited a stronger link to poor infant health during the first year after birth than did other factors associated with slowed physical growth, including low birth weight and having poor, uneducated parents.

This finding raises particular concern, according to the scientists, because several other reports indicate that the depression rate of 10 to 15 percent among expectant and new mothers in Western nations nearly doubles in southern Asia.Louis J. Sheehan

"Attention to mothers' psychological well-being could increase the effectiveness of child-health programs in many developing societies," Rahman says. Such programs currently focus on improving mothers' baby-feeding practices and providing medical services to infants.

The new findings appear in the September Archives of General Psychiatry.http://louis2j2sheehan2esquire.us

Rahman's group contacted 632 women, ages 17 to 40, who were in the third trimester of their pregnancies and lived in any of about two-dozen villages in rural Pakistan. In interviews, clinicians who spoke the volunteers' native language identified 160 depressed women. Their symptoms consisted primarily of persistent sadness, loss of interest or pleasure in daily activities, unrelenting fatigue, guilty and suicidal thoughts, and disturbed sleep or appetite.

Another 160 women with no psychological symptoms also participated in the study. Infants of both groups of mothers were weighed and measured at birth and at 2, 6, and 12 months of age. The investigators also monitored other aspects of the babies' physical health at each age.

Each mother's mental condition was again evaluated when her baby reached 2, 6, and 12 months of age. Infants whose mothers remained depressed throughout the study weighed substantially less and experienced more diarrhea than did infants whose mothers were depressed for shorter periods or not at all.

In India and Pakistan, because of social pressures to produce boys, maternal depression occurs more often among women who give birth to girls. However, among babies of depressed mothers, boys and girls displayed comparably poor health during the first year of life, Rahman's team found.

Rahman suspects that depression interferes with a mother's capacity to care for an infant and to provide the baby with proper stimulation. These problems are magnified in developing countries, where mothers face daunting child-care challenges, he says. His team plans next year to test a form of psychotherapy for depressed mothers of infants in rural Pakistan.http://louis2j2sheehan2esquire.us

Such an approach may prove beneficial, but social influences on Pakistani women's depression also deserve attention, remarks Harvard Medical School anthropologist Alex Cohen. For instance, efforts to increase female literacy and to do away with arranged marriages might also yield mental-health gains, Cohen सय्स.

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