Seventy years ago, in 1940, a popular science magazine published a short article that set in motion one of the trendiest intellectual fads of the 20th century. At first glance, there seemed little about the article to augur its subsequent celebrity. Neither the title, “Science and Linguistics,” nor the magazine, M.I.T.’s Technology Review, was most people’s idea of glamour. And the author, a chemical engineer who worked for an insurance company and moonlighted as an anthropology lecturer at Yale University, was an unlikely candidate for international superstardom. And yet Benjamin Lee Whorf let loose an alluring idea about language’s power over the mind, and his stirring prose seduced a whole generation into believing that our mother tongue restricts what we are able to think.

In particular, Whorf announced, Native American languages impose on their speakers a picture of reality that is totally different from ours, so their speakers would simply not be able to understand some of our most basic concepts, like the flow of time or the distinction between objects (like “stone”) and actions (like “fall”). For decades, Whorf’s theory dazzled both academics and the general public alike. In his shadow, others made a whole range of imaginative claims about the supposed power of language, from the assertion that Native American languages instill in their speakers an intuitive understanding of Einstein’s concept of time as a fourth dimension to the theory that the nature of the Jewish religion was determined by the tense system of ancient Hebrew.

Eventually, Whorf’s theory crash-landed on hard facts and solid common sense, when it transpired that there had never actually been any evidence to support his fantastic claims. The reaction was so severe that for decades, any attempts to explore the influence of the mother tongue on our thoughts were relegated to the loony fringes of disrepute. But 70 years on, it is surely time to put the trauma of Whorf behind us. And in the last few years, new research has revealed that when we learn our mother tongue, we do after all acquire certain habits of thought that shape our experience in significant and often surprising ways.

Whorf, we now know, made many mistakes. The most serious one was to assume that our mother tongue constrains our minds and prevents us from being able to think certain thoughts. The general structure of his arguments was to claim that if a language has no word for a certain concept, then its speakers would not be able to understand this concept. If a language has no future tense, for instance, its speakers would simply not be able to grasp our notion of future time. It seems barely comprehensible that this line of argument could ever have achieved such success, given that so much contrary evidence confronts you wherever you look. When you ask, in perfectly normal English, and in the present tense, “Are you coming tomorrow?” do you feel your grip on the notion of futurity slipping away? Do English speakers who have never heard the German word Schadenfreude find it difficult to understand the concept of relishing someone else’s misfortune? Or think about it this way: If the inventory of ready-made words in your language determined which concepts you were able to understand, how would you ever learn anything new?

SINCE THERE IS NO EVIDENCE that any language forbids its speakers to think anything, we must look in an entirely different direction to discover how our mother tongue really does shape our experience of the world. Some 50 years ago, the renowned linguist Roman Jakobson pointed out a crucial fact about differences between languages in a pithy maxim: “Languages differ essentially in what they must convey and not in what they may convey.” This maxim offers us the key to unlocking the real force of the mother tongue: if different languages influence our minds in different ways, this is not because of what our language allows us to think but rather because of what it habitually obliges us to think about.

Consider this example. Suppose I say to you in English that “I spent yesterday evening with a neighbor.” You may well wonder whether my companion was male or female, but I have the right to tell you politely that it’s none of your business. But if we were speaking French or German, I wouldn’t have the privilege to equivocate in this way, because I would be obliged by the grammar of language to choose between voisin or voisine; Nachbar or Nachbarin. These languages compel me to inform you about the sex of my companion whether or not I feel it is remotely your concern. This does not mean, of course, that English speakers are unable to understand the differences between evenings spent with male or female neighbors, but it does mean that they do not have to consider the sexes of neighbors, friends, teachers and a host of other persons each time they come up in a conversation, whereas speakers of some languages are obliged to do so.

On the other hand, English does oblige you to specify certain types of information that can be left to the context in other languages. If I want to tell you in English about a dinner with my neighbor, I may not have to mention the neighbor’s sex, but I do have to tell you something about the timing of the event: I have to decide whether we dined, have been dining, are dining, will be dining and so on. Chinese, on the other hand, does not oblige its speakers to specify the exact time of the action in this way, because the same verb form can be used for past, present or future actions. Again, this does not mean that the Chinese are unable to understand the concept of time. But it does mean they are not obliged to think about timing whenever they describe an action.

When your language routinely obliges you to specify certain types of information, it forces you to be attentive to certain details in the world and to certain aspects of experience that speakers of other languages may not be required to think about all the time. And since such habits of speech are cultivated from the earliest age, it is only natural that they can settle into habits of mind that go beyond language itself, affecting your experiences, perceptions, associations, feelings, memories and orientation in the world.

BUT IS THERE any evidence for this happening in practice?

Let’s take genders again. Languages like Spanish, French, German and Russian not only oblige you to think about the sex of friends and neighbors, but they also assign a male or female gender to a whole range of inanimate objects quite at whim. What, for instance, is particularly feminine about a Frenchman’s beard (la barbe)? Why is Russian water a she, and why does she become a he once you have dipped a tea bag into her? Mark Twain famously lamented such erratic genders as female turnips and neuter maidens in his rant “The Awful German Language.” But whereas he claimed that there was something particularly perverse about the German gender system, it is in fact English that is unusual, at least among European languages, in not treating turnips and tea cups as masculine or feminine. Languages that treat an inanimate object as a he or a she force their speakers to talk about such an object as if it were a man or a woman. And as anyone whose mother tongue has a gender system will tell you, once the habit has taken hold, it is all but impossible to shake off. When I speak English, I may say about a bed that “it” is too soft, but as a native Hebrew speaker, I actually feel “she” is too soft. “She” stays feminine all the way from the lungs up to the glottis and is neutered only when she reaches the tip of the tongue.

Guy Deutscher is an honorary research fellow at the School of Languages, Linguistics and Cultures at the University of Manchester. His new book, from which this article is adapted, is “Through the Language Glass: Why the World Looks Different in Other Languages,” to be published this month by Metropolitan Books.

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People used weights strapped to their ankles to build muscle at the University of Florida Health Science Center in Gainesville, Fla.

Bears emerge from months of hibernation with their muscles largely intact. Not so for people, who, if bedridden that long, would lose so much muscle they would have trouble standing.

Why muscles wither with age is captivating a growing number of scientists, drug and food companies, let alone aging baby boomers who, despite having spent years sweating in the gym, are confronting the body’s natural loss of muscle tone over time.

Comparisons between age groups underline the muscle disparity: An 80-year-old might have 30 percent less muscle mass than a 20-year-old. And strength declines even more than mass. Weight-lifting records for 60-year-old men are 30 percent lower than for 30-year-olds; for women the drop-off is 50 percent.

With interest high among the aging, the market potential for maintaining and rebuilding muscle mass seems nearly boundless. Pharmaceutical companies already are trying to develop drugs that could build muscles or forestall their weakening muscle without the notoriety of anabolic steroids. Food giants like Nestlé and Danone are exploring nutritional products with the same objective.

In addition, geriatric specialists, in particular, are now trying to establish the age-related loss of muscles as a medical condition under the name sarcopenia, from the Greek for loss of flesh. Simply put, sarcopenia is to muscle what osteoporosis is to bone.

“In the future, sarcopenia will be known as much as osteoporosis is now,” said Dr. Bruno Vellas, president of the International Association of Gerontology and Geriatrics.

Researchers involved in the effort say doctors and patients need to be more aware that muscle deterioration is a major reason the elderly lose mobility and cannot live independently.

“A doctor sees old people who are shrinking and getting weak, but there is no medical terminology that’s been created and made uniform to allow the doctor to make a diagnosis, look at possible causes, and make a treatment plan,” said Dr. Stephanie A. Studenski, a professor of medicine at the University of Pittsburgh.

Of course, commercial interests are at play as well. “If you are trying to sell drugs, you want to have a very clear criterion for diagnosing the problem and for endpoints to treat it,” said Dr. Thomas Lang of the University of California, San Francisco, who is working on techniques for diagnosing sarcopenia.

A task force of academic and industry scientists met in Rome last November and in Albuquerque last month and has submitted a proposed definition of sarcopenia for publication in a medical journal. The meeting received financial support from several drug companies and food companies.

Underscoring the focus on the condition among researchers, four European medical societies proposed a somewhat different definition, and Dr. Studenski is developing yet another.

Whatever the definition, experts say, sarcopenia affects about 10 percent of those over 60, with higher rates as age advances. One study estimated that disability caused by sarcopenia accounted for $18.5 billion in direct medical costs in 2000, equivalent to 1.5 percent of the nation’s health care spending that year.

Causes of the loss of muscle mass or strength might include hormonal changes, sedentary lifestyles, oxidative damage, infiltration of fat into muscles, inflammation and resistance to insulin. Some problems stem from the brain and nervous system, which activate the muscles.

Experts say the best approach to restoring or maintaining muscle mass and strength is exercise, particularly resistance training.

The National Institute on Aging is now sponsoring a controlled trial to test whether exercise can prevent disability in largely sedentary people, age 70 to 89. There is also some early evidence that nutrition, like vitamin D or high levels of protein, might help. “At this point, what we can say is that older people are at risk for eating too little protein for adequate muscle preservation,” said Dr. Elena Volpi of the University of Texas Medical Branch in Galveston.

Pharmaceutical companies are paying more attention to muscles, a part of the body they once largely ignored. A year ago, for instance, GlaxoSmithKline hired William Evans, a leading academic expert on sarcopenia, to run a new muscle research unit.

But with sarcopenia still not established as a treatable condition, “there is no real defined regulatory path as to how one would get approved in this area,” said R. Alan Ezekowitz, a research executive at Merck.

So for now, many companies are focusing on better defined illnesses like muscular dystrophy and cachexia, the rapid muscle wasting that can accompany cancer or other diseases.

One problem is that academic researchers and drug companies initially viewed sarcopenia as primarily a loss of muscle mass, a direct analogy to bone density in osteoporosis. Muscle mass can be measured by the same scans used for bone density.

But some studies have shown that strength, such as gripping force, or muscle function, as measured, say, by walking speed, are more important than mass in predicting problems seniors might have.

“There’s a lot more to the story than simply having a lot of muscle tissue,” said Brian C. Clark, an expert at Ohio University. “Most of the drug stuff has been targeting muscle mass.”

So the definition is shifting to include muscle strength and function. The academic-industry task force recommends testing whether a person can walk four meters, or about 13 feet, in four seconds. That can be tested by any doctor, without the special equipment needed to measure muscle mass or strength, said Roger A. Fielding of Tufts University, a leader of the task force.

Experts say that to win approval from regulators and reimbursement from insurers, a drug must do more than merely improve mass or strength. It must, for example, improve walking ability or prevent people from falling.

Or perhaps it could restore mobility faster after a person is bedridden. Older people can lose so much muscle during a prolonged hospital stay that they have to move to a nursing home.

Demonstrating such benefits and cost savings would help counter criticism that doctors and drug companies are trying to turn a natural consequence of aging into a disease.

“If you can get out of a nursing home in three weeks instead of three months, wouldn’t we say it is a useful thing?” said Dr. Studenski, who consults for drug companies.

Efforts to develop muscle drugs are still in early stages, and there have been setbacks.

But for inspiration, researchers can look to the bears, though scientists have no definitive answer to the animals’ youthful secret. Moreover, a study that has tracked 3,000 people for 50 years found that about 20 of them, now in their 80s, have not lost muscle mass.

“Maintaining the muscle is possible,” said Dr. Luigi Ferrucci of the National Institute on Aging, who directs the study, called the Baltimore Longitudinal Study of Aging. “We just don’t know the right formula yet.”

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A new study suggests several reasons for the nation’s rising Caesarean section rate, including the increased use of drugs to induce labor, the tendency to give up on labor too soon and deliver babies surgically instead of waiting for nature to take its course, and the failure to allow women with previous Caesareans to try to give birth vaginally.

Thirty-two percent of all births in the United States — nearly 1 in 3 — now occur by Caesarean section. The operations have been increasing steadily since 1996, setting records year after year, and have become the most common surgery in American hospitals. About 1.4 million Caesareans were performed in 2007, the latest year for which figures are available. The increases have caused debate and concern.

The concern arises because Caesareans pose a risk of surgical complications and research has found that they are more likely than normal births to cause problems that can put the mother back in the hospital and the infant in intensive care. Risks to the mother also increase with each subsequent Caesarean, because it raises the odds that the uterus will rupture in the next pregnancy, which can seriously harm both the mother and the baby.

Caesareans also increase the risk of dangerous abnormalities in the placenta during later pregnancies, which can cause hemorrhaging and lead to a hysterectomy. Repeated Caesareans can make it risky or even impossible to have a large family. In addition, costs for a Caesarean are nearly twice those for a vaginal delivery.

Most women who have had one or even two Caesareans can at least try to give birth vaginally, and studies have found that 60 to 80 percent succeed. But vaginal births after Caesarean sections have become increasingly uncommon.

Worries about the ever-increasing Caesarean rate led the National Institutes of Health to form a Consortium on Safe Labor, which performed a detailed analysis of electronic records from 228,668 births at 19 hospitals in the United States from 2002 to 2008. The study is the first to analyze how often Caesareans were performed before women went into labor (more than half the time) and how often after labor had begun.

The results were published this month by the American Journal of Obstetrics and Gynecology, and described in a telephone briefing by two of the authors, Dr. Jun Zhang and Dr. S. Katherine Laughon, from the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Dr. Zhang said one thing that surprised him about the study was that a third of first-time mothers were having Caesareans. Although it was known that the overall Caesarean rate was 32 percent, some of that was thought to be due to repeat Caesareans.

The main reason for a Caesarean was a prior Caesarean. But in women who have not had Caesareans before, one factor that may increase the risk is the use of drugs to induce labor. The practice has been increasing, and the study found that induced labor, compared with spontaneous labor, was twice as likely to result in a Caesarean.

In the study, 44 percent of the women who were trying vaginal delivery had their labor induced. When Caesareans were done after induction, half were performed before the woman’s cervix had dilated to six centimeters, “suggesting that clinical impatience may play a role,” the authors wrote. Full dilation is 10 centimeters, and a Caesarean before six centimeters may be too soon, the researchers said.

Like other studies, this one found that few women were offered a chance to try vaginal birth after Caesarean.

“Physicians and patients may be less committed” to the vaginal births, the authors said.

Dr. Zhang said it appeared likely that the Caesarean rate in this country would keep increasing, though he said he hoped it would never match the rates in Brazil (70 percent) or China (60 percent). If there is any hope of reducing the rate in the United States, or at least slowing the increase, he and his colleagues said, the key is to lower the rate among first-time mothers and increase the rate of vaginal birth after Caesarean.

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King crab fishing in the Bering Sea is dangerous business, but contrary to what the cable television show suggests, it is not the deadliest catch.

Commercial fishing is, by almost any measure, the most dangerous profession in the United States. And the most dangerous fishing ground is the Northeast Coast, where fishermen go after groundfish — the bottom-dwelling species like flounder, sole and cod.

The Alaska Bering Sea crab fishery — the one featured on “Deadliest Catch” — is the fourth most dangerous, behind the Atlantic scallop fishery and fishing for West Coast Dungeness crabs.

The most recent report includes data collected from 2000 through 2009, a period that saw 504 fishing deaths.

“There are different hazards in different fisheries,” said Jennifer Lincoln of the Centers for Disease Control and Prevention, the lead author of the study. “In the Northeast, they go to sea for longer periods of time and further out to sea with larger crews. So when a vessel sinks, there are more lives at risk. The Gulf of Mexico is warmer water; New England is cold.” This, she said, means different dangers for each, and different safety measures required.

In the 1990s, measures recommended by the C.D.C. significantly reduced accidents and fatalities in the Alaska crab fishery. Then in 2007, the agency expanded its surveillance to include the rest of the country’s fishing areas, and found that there were fisheries even more problematic than Alaska’s.

Fatality rates were calculated using the number of vessels, the number of days at sea and the average number of crew members aboard each vessel. This yields the number of full-time-equivalent commercial fishermen.

There have been improvements, especially in the Alaska fishery, but Dr. Lincoln, who is an injury epidemiologist, said there was still much work to be done.

Although more people are surviving vessel losses, she said, the share of fatalities from falls overboard is unchanged, at 30 percent. “That’s one person at a time,” she said, “and it doesn’t make the headlines.”

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The number of child athletes taken to emergency rooms with sports-related concussions doubled over a recent 10-year-period, a new study reports, even though participation in team sports decreased slightly during the period, from 1997 to 2007.

Among youths aged 14 to 19, meanwhile, emergency room visits for concussions sustained during team sports more than tripled over the same period.

Over all, children aged 8 to 19 had more than half a million emergency room visits for concussion from 2001 through 2005, according to the study.

The paper, published in the journal Pediatrics, is one of the first studies looking at emergency department visits and concussions among younger athletes.

Researchers used data from the National Electronic Injury Surveillance System, which collects information from hospitals, to analyze emergency room visits for children aged 8 to 13, as well as for teenagers aged 14 to 19. Data about participation in sports were obtained from the National Sporting Goods Association.

About half of all the emergency department visits for concussion were sports-related, the study found, and the younger children sustained 40 percent of them, representing more than half the concussions among this age group.

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Imagine cutting out a diseased appendix without ever having seen a Gray’s Anatomy diagram, or calculating drug doses without a Physicians’ Desk Reference, and you’ll have an idea what it’s like to practice medicine in Afghanistan.

Nearly three decades of war and religious extremism have devastated medical libraries and crippled the educational system for doctors, nurses and other health professionals. Factions of the Taliban, which ruled Afghanistan from 1996 to 2001, singled out medical texts for destruction, military medical personnel say, because anatomical depictions of the human body were considered blasphemous.

“They not only burned the books, but they sent monitors into the classroom to make sure there were no drawings of the human body on the blackboard,” said Valerie Walker, director of the Medical Alumni Association of the University of California, Los Angeles.

Ms. Walker is helping lead an ambitious effort by American doctors and nurses, both civilian and military, to restock Afghanistan’s hospitals, clinics and universities with medical textbooks and other reference materials.

The project, called Operation Medical Libraries, began modestly in 2007 with a plea for books from a U.C.L.A. medical graduate serving in the Army. It has since been embraced by 30 universities and hospitals, more than a dozen professional organizations and scores of individual doctors and nurses.

“It’s hard to imagine working in an environment where you don’t have access to medical literature or the Internet,” said one donor, Dr. Lawrence Maldonado, director of the medical intensive care unit at Cedars-Sinai Medical Center in Los Angeles. “I have unbelievable resources where I work — libraries, lecture series, online — and I know that everything I read or learn helps me make better decisions and take better care of patients.”

Like most others involved in the program, Dr. Maldonado heard about it from a colleague. And word has spread among medical officers stationed in Afghanistan, who act as volunteer points of contact to shepherd books to the libraries.

One of them is Cmdr. David T. Beverly IV, a Navy ophthalmologist stationed at Camp Eggers in Kabul. The books he gets — 30 boxes so far — go to rebuild the library at Kabul Medical University, where most Afghan doctors receive their education, and at the nearby Afshar Hospital. “They’ve started a family medicine residency there using our books,” Commander Beverly said in a phone interview from Kabul.

By Ms. Walker’s estimate, 27,000 medical texts have reached Afghanistan through Operation Medical Libraries, but she adds that the number is probably much higher. Donors can contribute directly by visiting the project’s Web site, http://opmedlibs.medalumni.ucla.edu, to find a military volunteer’s address, then shipping the books on their own.

The system had some initial bugs. Col. Susan Bassett, an Air Force nurse stationed at an outpost hospital near Kandahar in 2008, said the first boxes she received were huge and heavy. “The people sending them didn’t realize we don’t have much equipment here — no dollies or anything to get the boxes on and off the trucks,” she said. So she spoke to Ms. Walker, who “put out the word to send smaller boxes.”

Colonel Bassett was assigned to serve as a mentor to Afghan Army nurses, so she was delighted to find books on medical diets, nursing, pharmacology and physical therapy among the donations — along with personal greetings from the donors.

“They all came with these homey notes: ‘Hope these help.’ ‘Hope you’re safe,’ ” said Colonel Bassett, who is now stationed at Keesler Air Force Base in Biloxi, Miss. “The generosity and kindness of Americans, well, it just warmed my heart.”

While most of the books go to Afghanistan, some have found their way to medical libraries in places as far-flung as Mozambique, the Solomon Islands and Uganda. Books on biology, chemistry, anatomy, medicine, nursing, dentistry, pharmacology and physical therapy are all in demand — especially those published in the last five years.

The operation started with an e-mail that landed in Ms. Walker’s in box in April 2007, addressed simply “U.C.L.A. Medical Alumni Association.” Lt. Col. Laura Pacha, a 1998 graduate serving as an Army medical officer in Iraq, described a crippled medical education system and inadequate reference libraries.

“Sadly, anything since 1994 is considered current here,” she wrote, adding that a dearth of computers and frequent electricity failures made online resources largely inaccessible. She wondered if her fellow alumni might have books to spare, and provided her military address.

Ms. Walker, whose previous experience with donation drives was helping her daughter on Girl Scout projects, tackled the details. First she arranged for a campus bookstore to receive donations and got a commitment from the university’s R.O.T.C. commander to ship the books through military channels. Then she sent an e-mail blast to medical school alumni, summarizing Colonel Pacha’s request and the collection plan.

That first salvo went to medical school graduates in the Los Angeles area; Ms. Walker assumed they would be most likely to respond because they could drive their books to campus. But her e-mail recipients had other ideas, forwarding the message to colleagues and distant medical school classmates. Books began pouring in, for a total of 2,000 volumes in that first shipment.

Ms. Walker did not realize what she and Colonel Pacha had started. “I thought this was a one-time deal,” she said.

But the word was spreading. In January 2008, Ms. Walker heard from a Navy doctor in Afghanistan, who said the lack of textbooks was forcing medical students to rely almost entirely on lecture notes and memorization. Could she send him some books too?

Getting books wasn’t the problem. The donations had never really stopped.

Dr. Christina S. Han, now a fellow in maternal and fetal medicine at Yale, delivered 60 boxes to Ms. Walker after organizing a competitive book drive at the Los Angeles hospital where she was a resident.

Dr. Michael D. Stouder, a family physician in Mission Viejo, Calif., drove a carload of donations to Ms. Walker’s office after hearing about the condition of Afghanistan’s libraries from his son, an Army psychologist.

And Mark McKenney, at St. Mary’s Hospital in Grand Junction, Colo., learned of the effort via an e-mail list for medical librarians. He persuaded administrators to include book drives for Afghanistan as part of his hospital’s community service mission.

Meanwhile, Ms. Walker set about building an Internet-based structure that would enable Operation Medical Libraries to run at no cost to her university or the military. The biggest challenge, she said, was to develop an economical and reliable shipping system.

Colonel Pacha’s suggestion that donations be shipped to her military address turned out to be the answer. The project now asks volunteers from the military to provide their addresses, enabling individual donors to ship at domestic bulk-mail rates of about 50 cents a pound, with no taxes or customs fees.

“You do everything through the U.S. mail service, so things don’t get lost,” Ms. Walker said. “We’ve sent well over 30 tons and haven’t lost a box yet.”

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DEBUNKER Dr. Donald A. Redelmeir is an internist-researcher in Toronto.

Presidential elections can be fatal.

Win an Academy Award and you’re likely to live longer than had you been a runner-up.

Interview for medical school on a rainy day, and your chances of being selected could fall.

Such are some of the surprising findings of Dr. Donald A. Redelmeier, a physician-researcher and perhaps the leading debunker of preconceived notions in the medical world.

In his 20 years as a researcher, first at Stanford University, now at the University of Toronto, Dr. Redelmeier, 50, has applied scientific rigor to topics that in lesser hands might have been dismissed as quirky and iconoclastic. In doing so, his work has shattered myths and revealed some deep truths about the predictors of longevity, the organization of health care and the workings of the medical mind.

“He’ll go totally against intuition, and come up with a beautiful finding,” said Eldar Shafir, a professor of psychology and public affairs at Princeton University who has worked with Dr. Redelmeier on research into medical decision-making.

Dr. Redelmeier was the first to study cellphones and automobile crashes. A paper he published in The New England Journal of Medicine in 1997 concluded that talking on a cellphone while driving was as dangerous as driving while intoxicated. His collaborator, Robert Tibshirani, a statistician at Stanford University, said the paper “is likely to dwarf all of my other work in statistics, in terms of its direct impact on public health.”

As an internist who works at Sunnybrook Hospital in Toronto, Canada’s largest trauma center, Dr. Redelmeier sees a large number of patients in the aftermath of crashes. As a result, one of his abiding professional preoccupations is with vehicle crashes. He found that about 25 more people die in crashes on presidential Election Days in the United States than the norm, which he attributes to increased traffic, rushed drivers and unfamiliar routes.

He also discovered a 41 percent relative increase in fatalities on Super Bowl Sunday, which he attributed to a combination of fatigue, distraction and alcohol. After publication of the findings on the Super Bowl, the National Highway Traffic Safety Administration embarked on a campaign with the slogan “Fans don’t let fans drink and drive.”

In preparation for a recent interview in his modest office in the sprawling hospital complex, Dr. Redelmeier had written on an index card some of his homespun philosophies.

“Life is a marathon, not a sprint,” he read, adding, “A great deal of mischief occurs when people are in a rush.”

To that end, he studied the psychology around changing lanes in traffic. In an article published in Nature in 1999, Dr. Redelmeier and Professor Tibshirani found that while cars in the other lane sometimes appear to be moving faster, they are not.

“Every driver on average thinks he’s in the wrong lane,” Dr. Redelmeier said. “You think more cars are passing you when you’re actually passing them just as quickly. Still, you make a lane change where the benefits are illusory and not real.” Meanwhile, changing lanes increases the chances of collision about threefold.

Often he works from a hunch. In the Canadian Medical Association Journal in December, Dr. Redelmeier examined University of Toronto medical school admission interview reports from 2004 to 2009. After correlating the interview scores with weather archives, he determined that candidates who interviewed on foul-weather days received ratings lower than candidates who visited on sunny days. In many cases, the difference was significant enough to influence acceptance.

Dr. Redelmeier’s work on longevity began 10 years ago, when he was watching the Academy Awards and noticed that the celebrities on stage “don’t look anything like the patients I see in clinic,” he said. “It’s not just the makeup and the plastic surgery and wardrobe. It’s the way they move, it’s their gestures. They seem so much more vivacious. It seemed so much more than skin deep and might go all the way to longevity.”

His findings: Academy Award winners live an average of three years longer than the runners-up. A potential explanation could be an added measure of scrutiny, a public expectation of healthier living.

Dr. Redelmeier did not set out to be a researcher. “For years, I thought I’d be a straight clinician,” he said. But during his years at Stanford in the 1980s and early 1990s, first as a medical resident, then as a fellow, he met Amos Tversky, the cognitive psychologist who helped inspire the field of behavioral economics, which examines the cognitive, social and emotional aspects of people’s financial decisions.

Professor Tversky, who was Dr. Redelmeier’s fellowship supervisor, changed Dr. Redelmeier’s thinking entirely.

In 1990, he and Professor Tversky published a paper in The New England Journal of Medicine showing that when physicians make a medical decision for a single hypothetical patient, they favor more expensive treatments than when making a decision for a group of hypothetical patients with similar symptoms. And in 1996 the two scientists found that increased arthritis pain had nothing to do with the weather. They attributed the misperception to the human tendency to look for patterns even where none may exist.

Dr. Redelmeier credits Professor Tversky, who died in 1996, with shaping his own approach to research in the medical realm. “He provided me with a language and a logic for tackling issues that seemed to be around me all the time, but weren’t so apparent to other people,” he said.

Dr. Redelmeier isn’t one to forget about his past research. With the Academy Award study, for instance, he regularly updates the database.

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Historically speaking, people with the bad luck to develop an infection have never had it so good. Modern medicine can deploy a vast array of antibiotics and other tools for their benefit.

For some of them, though, our shiny, state-of-the-art treatment includes a direct carryover from the Middle Ages.

These are the people who are not just infected on the inside but also infested on the outside, covered with germs. And when they are hospitalized we hustle them into an isolation room, and no matter how much they may protest and complain, and no matter how cumbersome it makes the rest of their medical care, we never let them out.

Isolation must be one of the oldest medical tools, and in some ways it is one of the most brutal. Purists routinely point out that no one has ever definitively proved that it accomplishes its goals any better than, say, assiduous hand washing and the enthusiastic use of bleach. But isolation is probably too primal and entrenched a practice ever to be studied in the usual dispassionate way.

We have at least improved a little on standard 14th-century medical practice by understanding more about how germs behave.

So we keep patients with active tuberculosis in rooms specially ventilated, so that in theory, germs do not rush out into the public corridor when the door is opened. All visitors wear tight-fitting masks, but gloves and gowns are unnecessary, as TB does not spread by touch.

Touch does, however, transmit methicillin-resistant staph, or MRSA, and the other antibiotic-resistant bacteria that are the bane of many hospitals these days. In ours, some of the isolation rooms go to people harboring these germs, but most now are occupied by patients with the intestinal infection called C. difficile colitis.

This organism is a spore-former: it makes small, hard seeds that cling to surfaces and parachute all over the place. Patients are, to use the unusually evocative technical terms, covered with a fecal veneer and they move in a fecal cloud.

A microscopic version of Google Earth, scanning them in and out, would show a small, malevolent universe consisting of a human being surrounded by a shimmering, human-shaped cloud of bacteria. When patients turn in bed, giant waves of bacteria rise and travel on air currents all over the room, landing on bedside tables, on adjacent beds and on the people in those beds. The palms of people who touch these patients turn gritty with bacteria, and every time those caring hands touch another patient, the bacteria stick fast.

Our hospital’s current policy for avoiding the resulting outbreaks of infection is typical of most: every patient with diarrhea is isolated until we have proven C. difficile is not causing the problem. Each goes into a private room, with boxes of disposable gloves and gowns by the door, which remains closed.

These gowns are thick yellow paper smocks individually wrapped in plastic, with cotton-knit cuffs and ties that wrap around the waist. The gloves are standard-issue vinyl, packed into boxes of S, M and L. Putting on the gloves and gowns takes a couple of minutes (unless the supplies are missing or we are down to the ridiculously tiny size S gloves, in which case the search for replacements can go on quite a while).

Then you have to take it all off again: the gown is untied and peeled over the gloves, which go off last, optimally sequestered in a bundle of contaminated surfaces all facing inward. The bundle must be stuffed into the red can of contaminated garbage, which is invariably full. Then the hands are washed (with soap and water, as clostridial spores laugh at alcohol-based cleansers). Then it is on to the next patient and, often, the same ritual.

Isolation is an immense nuisance for everyone.

For a nurse rushing in and out of patients’ rooms dozens of times a day, all that dressing and undressing is just not possible. Nurses learn to change their routines to get everything done in fewer visits.

Meanwhile, patients with diarrhea need a lot of nursing care. They may begin to complain they are getting very short shrift in that department and, come to think of it, are not seeing the doctors much either. These patients feel terrible anyway, and they feel even worse feeling terrible all alone.

Any intimation that isolated patients are at risk of substandard medical care will elicit passionate denials from all individuals and institutions involved. But some data argue otherwise.

Researchers have repeatedly demonstrated that doctors and nurses alike visit the isolated less often. One study found that isolated patients had six times the usual rates of hospital-associated complications like pressure sores and falls.

Some isolated patients say they enjoy the privacy, but most complain of feeling lonely and stigmatized. On one survey, isolated patients consistently responded less enthusiastically than others to nearly every question about their hospital experience (although they did not complain enough to make a statistical difference).

On the surface, after all, all sick people are pretty much the same: disheveled, unhappy men and women lying in bed, wishing they were somewhere else. For centuries, the doctor’s challenge has been to see the individual patient lying within the cloud of illness.

But for isolated patients, the challenge has become just the reverse: the doctor must turn away from the individual and minister primarily to that invisible, evanescent cloud.

It is hard to say which is the more difficult.

A fragile old woman was admitted to our hospital not long ago, sick and confused, a few specks of raspberry lipstick still clinging bravely to her lower lip. During the day, propped up in a chair in the corridor, she seemed to take pleasure in the frantic comings and goings of the ward. At night, she cried inconsolably.

After a few days she developed a bad case of diarrhea. The nurses — moving, it seemed, more slowly than usual — arranged her and her belongings on her bed and wheeled it toward an isolation room. You could hear her sobbing all the way down the hall, even after the door closed behind her.

Those of us not involved in her care never saw her again, but when we passed by her room we often heard those muffled sobs until she died a few weeks later.

Increasingly, modern medicine forces us to specialize in the invisible. Here we had invisible germs with an inviolable mandate, and an all too visible patient pleading with us to ignore it. It was quite a struggle to try to see the one, to try not to see the other.

Dr. Abigail Zuger, who writes the monthly Books column, is an infectious-disease physician in Manhattan.

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