小红猪小分队 发表于2008-01-1 星期二 10:17 分类: 健康 , 医学 , 小红猪翻译小分队 | | BYLINE: Vivien Marx, Graham Lawton. Vivien Marx is a writer based in New York SECTION: FEATURES; Feature; Pg. 40-43 LENGTH: 2625 words IMAGINE a quick and simple surgical procedure that trials have shown could give your newborn child lifelong protection against HIV and may ward off sexually transmitted diseases and cancer too. It involves a little pain and bleeding, and occasionally goes wrong, but the risk of serious adverse effects is tiny. Would you have it done? Chances are you would. But what if you found out that other trials have called the procedures benefits into question, and that it involves cutting off part of your childs penis. Now how do you feel about it? This, in a nutshell, is the dilemma facing the parents of newborn baby boys. According to the increasingly vocal advocates of male circumcision, slicing off the foreskin is one of the most effective public-health measures ever invented and should be done routinely, like vaccination. Not so fast, say opponents. They insist that circumcision has no medical benefits and damages a mans sex life. The debate has rumbled on for decades, but recent findings about the role circumcision can play in preventing transmission of HIV have placed the foreskin - or its absence - firmly back on the public-health agenda. Globally, approximately 30 per cent of men have been circumcised, making it probably the worlds most common surgical procedure, says epidemiologist Helen Weiss of the London School of Hygiene Tropical Medicine. Most circumcisions are carried out for cultural or religious reasons, but there have long been those who advocate the procedure on medical grounds, to improve hygiene and prevent infections. The latest disease claimed by the circumcision lobby is HIV. Back in the mid-1980s, an American urologist called Aaron Fink noted that a large proportion of the men in Africa who had AIDS were uncircumcised (The New England Journal of Medicine , vol 315, p 1167). Over the next few years, stacks of observational evidence came in suggesting that circumcised men were less likely to be HIV-positive, and by 2000 the idea was widely accepted (AIDS , vol 14, p 2361). What was still needed, however, was proof from a large, randomised clinical trial that circumcision could protect men against the virus. The first study of this kind to report results began in July 2002 at Orange Farm, a large township near Johannesburg in South Africa. It was supposed to run for three years but was halted early when a halfway analysis showed that circumcision was lowering HIV infection rates by 60 per cent - a result that had trial leader Bertran Auvert of the French National Institute of Health and Medical Research (INSERM) in Saint-Maurice comparing circumcision to a vaccine of high efficacy (PLoS Medicine , vol 2, p e298). Two more big trials, one in Kisumu, Kenya, and the other in Rakai, Uganda, were also stopped early on the strength of overwhelmingly positive results. When these two studies were published in The Lancet (vol 369, p 643, and p 657) an accompanying editorial declared a new era for HIV prevention (The Lancet , vol 369, p 615). Auvert calculated that circumcision could avert up to 3.8 million infections and half a million deaths in sub-Saharan Africa between 2006 and 2016, and up to 5.8 million deaths by 2026 (PLoS Medicine , vol 3, p e262). Circumcision primarily protects men during heterosexual intercourse, but it also appeared to benefit women. Anthony Fauci of the US National Institute of Allergy and Infectious Diseases - which helped to fund the Kisumu and Rakai trials - greeted the results with the comment: While the initial benefit will be fewer HIV infections in men, ultimately circumcision could lead to fewer infections in women in those areas of the world where HIV is spread primarily through heterosexual intercourse. So how does circumcision protect against HIV? As Brian Morris, a molecular biologist at the University of Sydney in Australia and a leading supporter of circumcision, explains, it is the inner lining of the foreskin that is the weak point. While the virus does not easily pass through the keratinised skin of the foreskins outer surface and the penis shaft, the inner surface of the foreskin lacks keratin and is packed with immune cells such as Langerhans cells that HIV uses as an entry point. This makes it very, very vulnerable, says Morris. HIV goes straight in. The African trials have encouraged the World Health Organization and Joint United Nations Programme on HIV/AIDS (UNAIDS) to set up programmes to help African countries establish or scale up circumcision services for adult men - though they emphasise that circumcision does not make men immune, and that couples should still practise safe sex. This is a huge opportunity for prevention, particularly in areas of Africa with high HIV prevalence, says Daniel Halperin, an epidemiologist at Harvard School of Public Health and former global HIV adviser at USAID, the US Agency for International Development. To me, this is the greatest medical advance in 20 years, adds Jeffrey Klausner, who directs sexually transmitted disease prevention and control services for San Franciscos Department of Health. Yet as with most things circumcision-related, all is not necessarily as it first seems - starting with the trials themselves. Numerous criticisms levelled at their design and execution have cast doubt on whether circumcision will be anywhere near as effective in the real world as the results suggest (Future HIV Therapy , vol 2, p 193). It is widely recognised, for example, that clinical trials which are stopped early because the results are good generally exaggerate the beneficial effect (The Lancet , vol 368, p 1236). Many researchers argue that if the trials had continued for the full three years and beyond, many more circumcised men would have caught the virus. According to Michel Garenne of the Pasteur Institute in Paris, France, factors like this make the vaccine analogy highly misleading. A 60 per cent reduction in infection rate over 18 months is not the same as the near-complete protection offered by a vaccine, and may not do very much to protect men over a lifetime of sexual activity (PLoS Medicine , vol 3, p e78). He also warns against generalising from the studies which found that circumcised men tend to have lower rates of HIV, pointing out that in some countries - notably Cameroon, Lesotho and Malawi - the opposite is true (African Journal of AIDS Research , vol 7, p 1). Then there is the issue of whether circumcision protects women. At a major AIDS conference earlier this year, a team from Johns Hopkins University in Baltimore, Maryland, reported that men who are circumcised when they are already HIV-positive are more likely to infect their partners. The reason, according to team leader Maria Wawer, is that some couples resume sex too early, before the circumcision wound heals, thus exposing the woman to virus-infected blood. Of course, circumcision cannot protect men who are already HIV-positive, but the fear is that if circumcision becomes the norm such men will have the procedure done - either because they dont know they are infected or because uncircumcised penises come to be seen as a marker of being HIV-positive. Another fear is that circumcision could encourage risky sexual behaviour by lulling men into a false sense of security, or even making them believe they are immune and so can stop using condoms. Auverts team has estimated that this effect would reduce the effectiveness of circumcision from 60 per cent to 50 per cent (PLoS Medicine , vol 3, p e517). Another model found that if 40 per cent of circumcised men significantly increased their risky behaviour, the benefits of circumcision would be completely eliminated (International Journal of Epidemiology , DOI: 10.1093/ije/dyn038). However, a real-world Kenyan study found no increase in risky sex acts such as failure to use a condom among recently circumcised men (Journal of Acquired Immune Deficiency Syndromes , vol 44, p 66). As the controversy over circumcision in Africa continues, it has spilled over into a secondary debate in the western world. If circumcision is an effective weapon against AIDS in Africa, does that mean it should be promoted elsewhere? Convincing evidence one way or the other is thin on the ground. Huge regional differences in the nature of the epidemic mean that applying the African findings to other parts of the world is not straightforward, Halperin says. In sub-Saharan Africa, for example, the main mode of HIV transmission is heterosexual sex, whereas in the developed world it is sex between men, prostitution and injected drugs. That calls into question the public-health benefits of a procedure established only as a way of protecting men during sex with women. Whats more, HIV is much less prevalent in the west than in Africa, and the predominant subtype is HIV B, rather than A, C and D - factors which have unknown consequences for the effectiveness of circumcision. And while a handful of observational studies have looked at HIV and circumcision in the west, the results have been inconclusive (PLoS Medicine , vol 4, p e223). Last year, the US Centers for Disease Control and Prevention (CDC) assessed evidence relating to HIV and concluded that there was no compelling reason to advocate widespread circumcision in the US, though there may be a case for certain high-risk men choosing to undergo the procedure. New York Citys health authorities have also considered whether to start promoting circumcision . But HIV is not the only reason advocates still claim that boys should be routinely circumcised. They point to a large and growing body of evidence - though much of it is disputed and none of it is yet from randomised controlled trials - that circumcision can prevent numerous other health problems, from mild urinary tract infections to cancer. Some studies have shown, for example, that circumcised baby boys have a lower rate of urinary tract and kidney infections. Others find that uncircumcised men have a higher risk of catching sexually transmitted diseases, including chlamydia, genital warts, herpes, gonorrhea, syphilis and chancroid. Circumcision also prevents a problem called phimosis, where the foreskin is overly tight making erections and urination painful; phimosis is a strong predisposing factor for penile cancer. Circumcision also offers protection against human papilloma virus (HPV), another cause of penile cancer. One recent review concluded that uncircumcised men are more than 20 times as likely to get penile cancer (Journal of the American Academy of Dermatology , vol 54, p 369). Some studies even show that uncircumcised men have a higher incidence of sexual dysfunction. All in all, says Morris, 1 in 3 uncircumcised men will eventually require medical attention for a condition that could have been prevented by circumcision. There are benefits at all ages, he says. There is a huge public-health problem if youre not circumcising (BioEssays , vol 29, p 1147). There are also claimed health benefits for women. The female sexual partners of uncircumcised men have a moderately increased risk of cervical cancer, probably due to HPV, along with an elevated incidence of herpes and chlamydia. Despite this, medical authorities are loath to promote circumcision. The American Academy of Pediatrics is looking into the issue in the light of the HIV data but its current position is that the potential medical benefits are not sufficient to recommend routine circumcision. The British Medical Association, meanwhile, describes the medical evidence as equivocal. These positions are echoed by authorities across the developed world. One reason for this caution is the risk of complications arising from the procedure. These are largely minor, such as bleeding, pain and the side effects of anaesthesia. But very occasionally they can be more serious: a few cases of severe infection or injury and even death have been recorded. Figures for the incidence of complications are inconsistent, however, not least because the conditions under which circumcision is performed vary so widely. The CDC says that somewhere between 0.2 and 2 per cent of circumcisions in the US result in complications, almost all of them minor. This uncertainty makes the relative costs and benefits of circumcision hard to calculate. For example, Morris reckons that circumcising just 1000 boys will prevent one case of penile cancer, but other analyses argue that the number is closer to 300,000. As the pro-circumcision message has gained momentum, anti-circumcision groups have proliferated, arguing that the supposed benefits are overblown and are outweighed by the risks. Some argue that circumcising a child without consent is a violation of his human rights. Circumcision is the harmful removal of a very important part of a mans body, says George Denniston of Doctors Opposing Circumcision in Seattle, Washington. Circumcision proponents say the objections are based on anecdotes rather than science. I dont think there is any evidence other than emotion that drives people to say we cause harm, says Irwin Goldstein, director of sexual medicine at the University of California, San Diego. The debate is at its most raucous and scientifically murky when it comes to sex. According to supporters, circumcision has no effect on a mans sex life and can improve that of his partners. Opponents say the exact opposite, claiming that the foreskin is a highly sensitive part of the penis that is necessary for normal sexual function and enjoyment. Here too, the science is equivocal. Some studies have shown that circumcised men have reduced sensation to fine touch (BJU International , vol 99, p 864). Many more, however, including one by William Masters and Virginia Johnson in their classic 1966 book Human Sexual Response , find no difference in penile sensitivity. A recent example is reported in The Journal of Sexual Medicine , vol 4, p 667. Outside the laboratory the results are equally contradictory. Most of the information comes from non-scientific surveys that tend to confirm the prejudices of the people carrying them out. In 1988, for example, circumcision advocate James Badger found that men who had experienced sex both uncircumcised and then after being circumcised said it was better circumcised, while women found circumcised penises more attractive. However, a similar survey by circumcision critic Kristen OHara found that women overwhelmingly preferred natural intercourse (BJU International, vol 83, p s79). The most recent contribution to the sex debate comes from the circumcision trial in Uganda. A team led by Ronald Gray of Johns Hopkins University compared two groups of more than 2000 men: the members of one group underwent circumcision at the start of the two-year study, while those in the other group remained uncircumcised throughout. When they asked the men about their sexual desire, functioning and satisfaction, the researchers found no significant difference (BJU International , vol 101, p 65). I think we need quite a bit more data on the direct effects of circumcision on penile sensation, says Erik Janssen, a sex researcher at the Kinsey Institute in Bloomington, Indiana. Is it leading to additional types of stimulation that are more pleasurable? I dont know of really good research on this topic; if there was funding for it, I would study it. For now, the debate over circumcision continues to arouse passion, prejudice and confusion on both sides. What is urgently needed is rock-solid data from randomised, controlled trials. Scientists keep an open mind, Morris advises. Ten years down the track, if there is evidence circumcision is not necessary, I will just back off. Vivien Marx is a writer based in New York. 标签： 翻译
小红猪小分队 发表于2008-01-7 星期一 10:27 分类: 医学 , 小红猪翻译小分队 , 生物 | | by Jerome Groopman August 11, 2008 Doctors fear that dangerous bacteria may become entrenched in hospitals. In August, 2000, Dr. Roger Wetherbee, an infectious-disease expert at New York Universitys Tisch Hospital, received a disturbing call from the hospitals microbiology laboratory. At the time, Wetherbee was in charge of handling outbreaks of dangerous microbes in the hospital, and the laboratory had isolated a bacterium called Klebsiella pneumoniae from a patient in an intensive-care unit. It was literally resistant to every meaningful antibiotic that we had, Wetherbee recalled recently. The microbe was sensitive only to a drug called colistin, which had been developed decades earlier and largely abandoned as a systemic treatment, because it can severely damage the kidneys. So we had this report, and I looked at it and said to myself, My God, this is an organism that basically we cant treat. Klebsiella is in a class of bacteria called gram-negative, based on its failure to pick up the dye in a Grams stain test. (Gram-positive organisms, which include Streptococcus and Staphylococcus , have a different cellular structure.) It inhabits both humans and animals and can survive in water and on inanimate objects. We can carry it on our skin and in our noses and throats, but it is most often found in our stool, and fecal contamination on the hands of caregivers is the most frequent source of infection among patients. Healthy people can harbor Klebsiella to no detrimental effect; those with debilitating conditions, like liver disease or severe diabetes, or those recovering from major surgery, are most likely to fall ill. The bacterium is oval in shape, resembling a TicTac, and has a thick, sugar-filled outer coat, which makes it difficult for white blood cells to engulf and destroy it. Fimbriafine, hairlike extensions that enable Klebsiella to adhere to the lining of the throat, trachea, and bronchiproject from the bacterias surface; the attached microbes can travel deep into our lungs, where they destroy the delicate alveoli, the air sacs that allow us to obtain oxygen. The resulting hemorrhage produces a blood-filled sputum, nicknamed currant jelly. Klebsiella can also attach to the urinary tract and infect the kidneys. When the bacteria enter the bloodstream, they release a fatty substance known as an endotoxin, which injures the lining of the blood vessels and can cause fatal shock. Tisch Hospital has four intensive-care units, all in the east wing on the fifteenth floor, and at the time of the outbreak there were thirty-two intensive-care beds. The I.C.U.s were built in 1961, and although the equipment had been modernized over the years, the units had otherwise remained relatively unchanged: the beds were close to each other, with I.V. pumps and respirators between them, and doctors and nursing staff were shared among the various I.C.U.s. This was an ideal environment for a highly infectious bacterium. It was the first major outbreak of this multidrug-resistant strain of Klebsiella in the United States, and Wetherbee was concerned that the bacterium had become so well adapted in the I.C.U. that it could not be killed with the usual ammonia and phenol disinfectants. Only bleach seemed able to destroy it. Wetherbee and his team instructed doctors, nurses, and custodial staff to perform meticulous hand washing, and had them wear gowns and gloves when attending to infected patients. He instituted strict protocols to insure that gloves were changed and hands vigorously disinfected after handling the tubing on each patients ventilator. Spray bottles with bleach solutions were installed in the I.C.U.s, and surfaces and equipment were cleaned several times a day. Nevertheless, in the ensuing months Klebsiella infected more than a dozen patients. In late autumn of 2000, in addition to pneumonia patients began contracting urinary-tract and bloodstream infections from Klebsiella . The latter are often lethal, since once Klebsiella infects the bloodstream it can spread to every organ in the body. Wetherbee reviewed procedures in the I.C.U. again and discovered that the Foley catheters, used to drain urine from the bladder, had become a common source of contamination; when emptying the urine bags, staff members inadvertently splashed infected urine onto their gloves and onto nearby machinery. They were very effectively moving the organism from one bed to the next, Wetherbee said. He ordered all the I.C.U.s to be decontaminated; the patients were temporarily moved out, supplies discarded, curtains changed, and each room was cleaned from floor to ceiling with a bleach solution. Even so, of the thirty-four patients with infections that year, nearly half died. The outbreak subsided in October, 2003, after even more stringent procedures for decontamination and hygiene were instituted: patients kept in isolation, and staff and visitors required to wear gloves, masks, and gowns at all times. My basic premise, Wetherbee said, is that you take a capable microrganism like Klebsiella and you put it through the gruelling test of being exposed to a broad spectrum of antibiotics and it will eventually defeat your efforts, as this one did. Although Tisch Hospital has not had another outbreak, the bacteria appeared soon after at several hospitals in Brooklyn and one in Queens. When I spoke to infectious-disease experts this spring, I was told that the resistant Klebsiella had also appeared at Mt. Sinai Medical Center, in Manhattan, and in hospitals in New Jersey, Pennsylvania, Cleveland, and St. Louis. Of the so-called superbugsthose bacteria that have developed immunity to a wide number of antibioticsthe methicillin-resistant Staphylococcus aureus , or MRSA , is the most well known. Dr. Robert Moellering, a professor at Harvard Medical School, a past president of the Infectious Diseases Society of America, and a leading expert on antibiotic resistance, pointed out that MRSA , like Klebsiella , originally occurred in I.C.U.s, especially among patients who had undergone major surgery. Until about ten years ago, Moellering told me, virtually all cases of MRSA were either in hospitals or nursing homes. In the hospital setting, they cause wound infections after surgery, pneumonias, and bloodstream infections from indwelling catheters. But they can cause a variety of other infections, all the way to bacterial meningitis. The first deaths from MRSA in community settings, reported at the end of the nineteen-nineties, were among children in North Dakota and Minnesota. And then it started showing up in men who have sex with men, Moellering said. Soon, it began to be spread in prisons among the prisoners. Now we see it in a whole bunch of other populations. An outbreak among the St. Louis Rams football team, passed on through shared equipment, particularly affected the teams linemen; artificial turf, which causes skin abrasions that are prone to infection, exacerbated the problem. Other outbreaks were reported among insular religious groups in rural New York; Hurricane Katrina evacuees; and illegal tattoo recipients. And now its basically everybody, Moellering said. The deadly toxin produced by the strain of MRSA found in U.S. communities, Panton-Valentine leukocidin, is thought to destroy the membranes of white blood cells, damaging the bodys primary defense against the microbe. In 2006, the Centers for Disease Control and Prevention recorded some nineteen thousand deaths and a hundred and five thousand infections from MRSA . Unlike resistant forms of Klebsiella and other gram-negative bacteria, however, MRSA can be treated. There are about a dozen new antibiotics coming on the market in the next couple of years, Moellering noted. But there are no good drugs coming along for these gram-negatives. Klebsiella and similarly classified bacteria, including Acinetobacter , Enterobacter , and Pseudomonas , have an extra cellular envelope that MRSA lacks, and that hampers the entry of large molecules like antibiotic drugs. The Klebsiella that caused particular trouble in New York are spreading out, Moellering told me. They have very high mortality rates. They are sort of the doomsday-scenario bugs. In 1968, Moellering travelled to Malaita, in the Solomon Islands. I was really interested to see whether we could find an antibiotic-resistant population of bacteria in a place that had never seen antibiotics, Moellering said. The natives practiced head-hunting and cannibalism, and were isolated as much by conflict as by the islands dense jungle. Moellering identified microbes there that were resistant to the antibiotics streptomycin and tetracycline, which were then in use in the West but had never been introduced clinically on Malaita. Later studies found resistant bacteria in many other isolated indigenous human populations, as well as in natural reservoirs like aquifers. Before the development of antibiotics, the threat of infection was urgent: until 1936, pneumonia was the No. 1 cause of death in the United States, and amputation was sometimes the only cure for infected wounds. The introduction of sulfa drugs, in the nineteen-thirties, and penicillin, in the nineteen-forties, suddenly made many bacterial infections curable. As a result, doctors prescribed the drugs widelyoften for sore throats, sinus congestion, and coughs that were due not to bacteria but to viruses. In response, bacteria quickly developed resistance to the most common antibiotics. The public assumed that the pharmaceutical industry and researchers in academic hospitals would continue to identify effective new treatments, and for many years they did. In the nineteen-eighties, a class of drugs called carbapenems was developed to combat gram-negative organisms like Klebsiella , Pseudomonas , and Acinetobacter . They were, at the time, thought to be drugs of last resort, because they had activity against a whole variety of multiply-resistant gram-negative bacteria that were already floating around, Moellering said. Many hospitals put the drugs on reserve, but an apparent cure-all was too tempting for some physicians, and the tight stewardship slowly broke down. Inevitably, mutant, resistant microbes flourished, and even the carbapenems effectiveness waned. Now microbes are appearing far outside their environmental niches. Acinetobacter thrives in warm, humid climates, like Honduras, as well as in parts of Iraq, and is normally found in soil. An article published in the military magazine Proceedings in February reported that more than two hundred and fifty patients at U.S. military hospitals were infected with a highly resistant strain of Acinetobacter between 2003 and 2005, with seven deaths as of June, 2006, linked to Acinetobacter -related complications. In 2004, about thirty per cent of all patients returning from Iraq and Afghanistan tested positive for the bacteria. Its a big problem, and its contaminated the evacuation facilities in Germany and a lot of the V.A. hospitals in the United States where these soldiers have been brought, Moellering said. Patients evacuated to Stockholm from Thailand after the 2004 tsunami were often infected with resistant gram-negative microbes, including a strain of Acinetobacter that was resistant even to colistin, the antibiotic used, to variable effect, in the outbreak at Tisch Hospital. The practice of clinical tourism, in which patients travel long distances for more advanced or more affordable medical centers, may introduce resistant microbes into hospitals where they had not existed before. Meanwhile, antibiotic use in agricultural industries has grown rapidly. Seventy per cent of the antibiotics administered in America end up in agriculture, Michael Pollan, a professor of journalism at Berkeley and the author of In Defense of Food: An Eaters Manifesto, told me. The drugs are not used to cure sick animals but to prevent them from getting sick, because we crowd them together under filthy circumstances. These are perfect environments for disease. And we also have found, for reasons that I dont think we entirely understand, that administering low levels of antibiotics to animals speeds their growth. The theory is that by killing intestinal bacteria the competition for energy is reduced, so that the animal absorbs more energy from the food and therefore grows faster. The Food and Drug Administration, which is often criticized for its lack of attention to the risks of widespread use of antibiotics, offers recommended, non-binding guidelines for these drugs but has rarely withdrawn approval for their application. A spokesman for the Center for Veterinary Medicine at the F.D.A. told me that the center believes that prudent drug-use principles are essential to the control of antimicrobial resistance. A study by David L. Smith, Jonathan Dushoff, and J. Glenn Morris, published by PLoS Medicine , from the Public Library of Science, in 2005, noted that the transmission of resistant bacteria from animal to human populations is difficult to measure, but that antibiotics and antibiotic-resistant bacteria ( ARB ) are found in the air and soil around farms, in surface and ground water, in wild-animal populations, and on retail meat and poultry. ARB are carried into the kitchen on contaminated meat and poultry, where other foods are cross-contaminated because of common unsafe handling practices. The researchers developed a mathematical model that suggested that the impact of the transmission of these bacteria from agriculture may be more significant than that of hospital transmissions. The problem is that we have created the perfect environment in which to breed superbugs that are antibiotic-resistant, Pollan told me. Weve created a petri dish in our factory farms for the evolution of dangerous pathogens. Ten years ago, the Institute of Medicine of the National Academy of Sciences, in Washington, D.C., assessed the economic impact of resistant microbes in the United States at up to five billion dollars, and experts now believe the figure to be much higher. In July, 2004, the Infectious Diseases Society of America released a white paper, Bad Bugs, No Drugs: As Antibiotic Discovery Stagnates . . . A Public Health Crisis Brews, citing 2002 C.D.C. data showing that, of that years estimated ninety thousand deaths annually in U.S. hospitals owing to bacterial infection, more than seventy per cent had been caused by organisms that were resistant to at least one of the drugs commonly used to treat them. Drawing on these data, collected mostly from hospitals in large urban areas which are affiliated with medical schools, the Centers for Disease Control and Prevention found more than a hundred thousand cases of gram-negative antibiotic-resistant bacteria. No precise numbers for all infections, including those outside hospitals, have been calculated, but the C.D.C. also reported that, among gram-negative hospital-acquired infections, about twenty per cent were resistant to state-of-the-art drugs. In April, I visited Dr. Stuart Levy, at Tufts University School of Medicine. Levy is a researcher-physician who has made key discoveries about how bacteria become resistant to antibiotics. In addition to the natural cell envelope of Klebsiella , Levy outlined three primary changes in bacteria that make them resistant to antibiotics. Each change involves either a mutation in the bacteriums own DNA or the importation of mutated DNA from another. (Bacteria can exchange DNA in the form of plasmids, molecules that are shared by the microbes and allow them to survive inhibitory antibiotics.) First, the bacteria may acquire an enzyme that can either act like a pair of scissors, cutting the drug into an inactive form, or modify the drugs chemical structure, so that it is rendered impotent. Thirty years ago, Levy discovered a second change: pumps inside the bacteria that could spit out the antibiotic once it had passed through the cell wall. His first reports were met with profound skepticism, but now, Levy told me, most people would say that efflux is the most common form of bacterial resistance to antibiotics. The third change involves mutations that alter the inner contents of the microbe, so that the antibiotic can no longer inactivate its target. Global studies have shown how quickly these bacteria can develop and spread. This has been a problem in Mediterranean Europe that started about ten years ago, Dr. Christian Giske told me. Giske is a clinical microbiologist at Karolinska University Hospital, in Stockholm, who, with researchers in Israel and Denmark, recently reported on the worldwide spread of resistant gram-negative bacteria. He continued, It started to get really serious during the last five or six years and has become really dramatic in Greece. A decade ago, only a few microbes in Southern Europe had multidrug resistance; now some fifty to sixty per cent of hospital-acquired infections are resistant. Giske and his colleagues found that infection with a resistant strain of Pseudomonas increased, twofold to fivefold, a patients risk of dying, and increased about twofold the patients hospital stay. Like other experts in the field, Giskes team was concerned about the lack of new antibiotics being developed to combat gram-negative bacteria. There are now a growing number of reports of cases of infections caused by gram-negative organisms for which no adequate therapeutic options exist, Giske and his colleagues wrote. This return to the preantibiotic era has become a reality in many parts of the world. 文章分段，下边算第二篇译文原文 Doctors and researchers fear that these bacteria may become entrenched in hospitals, threatening any patient who has significant health issues. Anytime you hear about some kid getting snatched, you want to find something in that story that will convince you that that family is different from yours, Dr. Louis Rice, an expert in antibiotic resistance at Louis Stokes Cleveland VA Medical Center, told me. But the problem is that any of us could be an I.C.U. patient tomorrow. Its not easy to convey this to people if its not immediately a threat. You dont want to think about it. But its actually anybody who goes into a hospital. This is scary stuff. Rice mentioned that he had a mild sinusitis and was hoping it would not need to be treated, because taking an antibiotic could change the balance of microbes in his body and make it easier for him to contract a pathogenic organism while doing his rounds at the hospital. Genetic elements in the bacteria that promote resistance may also move into other, more easily contracted bugs. Moellering pointed out that, while Klebsiella seems best adapted to hospital settings, and poses the greatest risk to patients, other gram-negative bacteriaspecifically E. coli , which is a frequent cause of urinary-tract infection in otherwise healthy peoplehave recently picked up the genes from Klebsiella which promote resistance to antibiotics. In the past, large pharmaceutical companies were the primary sources of antibiotic research. But many of these companies have abandoned the field. Eli Lilly and Company developed the first cephalosporins, Moellering told me, referring to familiar drugs like Keflex. They developed a huge number of important anti-microbial agents. They had incredible chemistry and incredible research facilities, and, unfortunately, they have completely pulled out of it now. After Squibb merged with Bristol-Myers, they closed their antibacterial program, he said, as did Abbott, which developed key agents in the past treatment of gram-negative bacteria. A recent assessment of progress in the field, from U.C.L.A., concluded, FDA approval of new antibacterial agents decreased by 56 per cent over the past 20 years (1998-2002 vs. 1983-1987), noting that, in the researchers projection of future development only six of the five hundred and six drugs currently being developed were new antibacterial agents. Drug companies are looking for blockbuster therapies that must be taken daily for decades, drugs like Lipitor, for high cholesterol, or Zyprexa, for psychiatric disorders, used by millions of people and generating many billions of dollars each year. Antibiotics are used to treat infections, and are therefore prescribed only for days or weeks. (The exception is the use of antibiotics in livestock, which is both a profit-driver and a potential cause of antibiotic resistance.) Antibiotics are the only class of drugs where all the experts, as soon as you introduce them clinically, we go out and tell everyone to try to hold it in reserve, Rice pointed out. If there is a new cardiology drug, every cardiologist out there is saying that everyone deserves to be on it. In February, Rice wrote an editorial in the Journal of Infectious Diseases criticizing the lack of support from the National Institutes of Health; without this support, he wrote, the big picture did not receive the attention it deserved. Rice acknowledges that there are competing agendas. As loud as my voice might be, there are louder voices screaming AIDS , he told me. And there are congressmen screaming bioterrorism. Rice came up with the acronym ESKAPE bacteria Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanni, Pseudomonas aeruginosa, and the Entero-bacter speciesas a way of communicating the threat these microbes pose, and the Infectious Diseases Society is lobbying Congress to pass the Strategies to Address Antimicrobial Resistance Act, which would earmark funding for research on ESKAPE microbes and also set up clinical trials on how to limit infection and antibiotic resistance. Rice has also proposed studies to determine the most effective useat what dosage, and for how longof antibiotics for common infections like bronchitis and sinusitis. Dr. Anthony Fauci is the director of the National Institute of Allergy and Infectious Diseases, which chairs the federal interagency working group on microbial resistance. Fauci told me that the government is acutely aware of the severity of the problem. He pointed out that the N.I.H. recently issued a call for proposals to study optimal use of antibiotics for common bacterial infections. It has also funded so-called coperative agreements, including one on Klebsiella , to facilitate public-private partnerships where the basic research from the institute or from university laboratories can be combined with development by a pharmaceutical or a biotech company. Even so, the total funding for studying the resistance of ESKAPE microbes is about thirty-five million dollars, a fraction of the two hundred million dollars provided by the NIAID for research on antimicrobial resistance, most of which goes to malaria, t.b., and H.I.V. The difficulty that we are faced with is that our budget has been flat for the last five years, Fauci told me. In real dollars, weve lost almost fifteen per cent purchasing power, because of an inflation index of about three per cent for biomedical research and development. Since September 11, 2001, significant funding has been directed toward the study of anthrax and other microbes, like the one that causes plague, which could be used as bioweapons. Although there is little concern that Klebsiella or Acinetobacter might be weaponized, the basic science of their mutation and resistance could be useful in helping us to understand these threats. Fauci hopes to make the case that funds for biodefense should be used to study the ESKAPE bugs, but, for now, he is quick to point out the challenge posed by a lack of resources. The problem is, it is extremely difficult to do a prospective controlled trial, because when people come into the hospital they immediately get started on some treatment, which ruins the period of study, he said, referring to research into the treatment of common infections. The culture of American medicine makes a study like that more difficult to execute. These types of studieson how often, and for how long, antibiotics should be prescribedare much easier to conduct in countries where medicine is largely socialized and prescriptions are tightly regulated. Recently, researchers in Israel, where most citizens receive their care through such a system, showed that refraining from empirically prescribing antibiotics during the summer months resulted in a sharp decline in ear infections caused by antibiotic-resistant microbes. (In the United States, a 1998 study estimated that fifty-five per cent of all antibiotics prescribed for respiratory infections in outpatients22.6 million prescriptionswere unnecessary.) In Sweden, the government closely monitors all infections, and has the power to intervene as needed. Our infection-control people have a lot of authority, Giske said. This is power from the legislation. Once a resistant microbe is identified, stringent protocols are put in place, with dramatic results. Fewer than two per cent of the staphylococci in Sweden are MRSA , compared with sixty per cent in the United States. Of course, its only around ten million people, so its possible to intervene because everything is smaller, Giske said, adding, Maybe Swedes are more used to this type of intervention and regulation. Stuart Levys laboratory occupies the eighth floor of a renovated building on Harrison Avenue in Bostons Chinatown, across the street from Tufts Medical Center. As I passed from his office into the corridor, I detected the acrid smell of agar, which is used to grow bacteria. That day, a laboratory technician was testing specimens taken from the eyes of people with bacterial conjunctivitis who had been given an antibiotic eye drop containing fluoroquinolone. Levy was comparing the bacteria from the infected eyes with those in the noses, cheeks, and throats of the same patients. His technician held up a petri dish with a cranberry-colored agar base. The patients specimen was growing bacteria that were susceptible to the antibiotic; the drug had created a large oval clear zone on the plate which resembled the halo around the moon. The study investigates whether an antibiotic applied to the eye would affect bacteria in the nose and mouth as well, which might indicate that what seems to be an innocuous and limited treatment may profoundly change a wider area of the body and foster resistant microbes. Levy has also received funding from the N.I.H. to study Yersinia pestis , the microbe that causes plague; the Department of Agriculture has sponsored his study of Pseudomonas fluorescens , a soil-based bacterium that has the potential to protect plants from microbial infection. He plans to develop it as a biocontrol agent, so that farmers can be weaned off the potent antibiotics and chemicals they use to treat their fields. We need to treat biology with biology, not chemistry, he said. In other studies, Levy and his team are looking at ways to render bacteria nondestructive and noninvasive, so that they might enter the body without harmful effects. This makes it necessary to identify virulence factorswhich parts of the bacteria cause damage to our tissues. Levys laboratory is targeting a protein in gram-negative organisms called MAR , which appears to act as a master switch, turning on both virulence genes and genes that mediate resistance, like the efflux pump. In collaboration with a startup company called Paratek, of which Levy is a co-founder, his laboratory is screening novel compounds in the hope of finding a drug that blocks MAR . Frederick Ausubel, a bacterial geneticist at the Massachusetts General Hospital, in Boston, is searching for drugs to combat bacterial virulence, using tiny animals like worms, which have intestinal cells that are similar to those in humans, and which are susceptible to lethal microbial infection. The worm that Ausubel is studying, Caenorhabditis elegans , is one and a half millimetres in length. You are probably going to have to screen millions of compounds and you cant screen millions of infected mice, Ausubel said. So our approach was to find an alternative host that could be infected with human pathogens which was small enough and cheap enough to be used in drug screens. Whats remarkable is that many common human pathogens, including Staphylococcus and Pseudomonas , will cause intestinal infection and kill the worms. So now you can look for a compound that cures it, that prevents the pathogen from killing the host. Ausubel first screened some six thousand compounds by hand and found eight, none of them traditional antibiotics, that may protect the worms. He is also attempting, among other potential solutions, to find a compound that would block what is called quorum sensing, in which bacteria release small molecules to communicate with one another and signal when a critical mass is present. Once this quorum is reached, the bacteria turn on their virulence genes. Bacteria dont want to alert their host that they are there by immediately producing virulence factors which the host would recognize, triggering the immune system, Ausubel explained. When they reach a certain quorum, there are too many of them for the host to do anything about it. Bonnie Bassler, a molecular biologist at Princeton University, has recently shown that it is through quorum sensing that cholera bacteria are able to accumulate in the intestines and release toxins that can be fatal; Pseudomonas is also known to switch on its virulence genes in response to signals from quorum sensing. Moellering is enthusiastic but cautious about this avenue of research. Its a great idea, but so far nobody has been able to make it work for human infections, he told me. With certain types of staphylococci , Moellering said, mutations have occurred spontaneously in nature that cut down on a number of virulence factors . . . but they still cause serious infections. Im not sure that we have a way yet to use what we know about virulence factors to develop effective antimicrobial agents. And we almost certainly will have to use these agents in combination with antibiotics. No one, Moellering said, has developed a way to disarm bacteria sufficiently to allow the human body to naturally and consistently defend against them. I asked him what we should do to combat these new superbugs. Nobody has the answer right now, he said. The fact of the matter is that we have found all the easy targets for drug development. He went on, So the only other thing we can do is continue to work on antibiotic stewardship. Meanwhile, new resistant bacteria, Moellering asserted, arent going to go away. We can temper things, we might be able to slow the rate of emergence of resistance, but its unlikely that we will ever be able to conquer it. 标签： 微生物 , 翻译
小红猪小分队 发表于2008-01-8 星期二 3:15 分类: 专辑 , 小红猪翻译小分队 | | 原文出自《新科学家》，链接为： http://environment.newscientist.com/channel/earth/mg19826621.500-oil-the-final-warning.html Section: Features Price is just the start of it. We need to kick the petroleum habit or well soon be in real trouble, says Ian Sample HOWLS of protest have been echoing round the globe as the price of oil punches through record highs with every passing week. In the UK, last month, hundreds of truckers descended on London to demand that planned fuel tax rises be scrapped. In continental Europe, where police clashed violently with truckers, two people died during the protests. Fishermen and farmers blockaded ports and depots in protest against the rocketing cost of diesel. Similar scenes played out across South America and Asia. In the US, the worlds thirstiest oil consumer, gasoline reached an all-time high of $4 per gallon, forcing the administration to lean on domestic producers and consider suing foreign oil exporters for allegedly rigging the market. When President Bush implored Saudi Arabia, which controls the lions share of the worlds proven reserves, to pump more from its wells, the Saudis came up with only a token increase. The situation is not about to improve. Bankers Goldman Sachs and Morgan Stanley have both suggested that the crude oil price could rise from the high of $139 a barrel (as New Scientist went to press) to $200 or more, while the financial speculator George Soros predicts that rising oil prices could send the US economy into recession. Expensive fuel at the pumps is just the start. These battles over the price of oil could be the harbinger of something even scarier. There is a growing realisation that we are teetering on the edge of an economic catastrophe which could be triggered next time there is a glitch in the worlds oil supply. A number of converging forces are making such an event more likely than ever before. First, there is the spectacular rise in global oil consumption, which, according to the International Energy Agency (IEA) now stands at 87 million barrels of crude (about 10 billion litres) a day. Most geologists now accept we have reached, or will imminently reach, peak oil. Some fields in the US and the North Sea have been pumped dry and production is becoming increasingly concentrated within fewer countries. Add a boost from speculators betting that things will get even worse, chicanery by the Organisation of Petroleum Exporting Countries (OPEC) cartel which over the past two years has added Angola and Ecuador to its ranks to mask the decline in production of its existing members, and its not hard to see why prices have been forced ever upwards. But price conceals the much more complex mess were in. In the past, it has usually been possible to ride out any disruption to world oil flows - whether from accidents or hostile acts - by pumping more oil from the ground. That spare capacity has now all but vanished, as oil producers cash in on soaring prices by extracting as much of the stuff as they can. There is absolutely no slack in the system any more, says Gal Luft, executive director of the Institute for the Analysis of Global Security, a Washington DC-based think tank specialising in energy security. It is this lack of wriggle-room that has brought us to the brink. In the days when oil producers had more leeway, they could make up for a disruption somewhere in the system by quickly raising production by around 3 million barrels a day, says Nick Butler, head of the Cambridge Centre for Energy Studies, part of the University of Cambridges Judge Business School. That crucial reserve capacity has now fallen below the daily output of some producers - meaning that if the taps were turned off in any one of a number of unstable oil-supplying nations, such as Nigeria, Iraq, Iran or Angola, the impact would be felt almost immediately. This has left the oil market so fragile that a few well-placed explosives, an energy-sapping cold winter or an unusually intense hurricane season could send shock waves across the globe. The potential consequences are so serious that governments are drawing up emergency plans to cope should the worst happen. According to one analyst who took part in a simulation of just such a crisis, the situation most experts fear is what they call a psychological avalanche. Heres what happens. A small, distant country one day finds it can no longer import enough oil because of a spike in prices or problems with local supply. The news media whip this up into a story suggesting an oil shock is on the way, and the resulting panic buying by the public degenerates into a global grab for oil. Most industrialised countries keep an emergency reserve as a first line of defence, but in the face of worldwide panic buying this may not be enough. Countries in which the oil runs out face transport meltdown, wreaking havoc with international trade and domestic necessities such as food distribution, emergency services and daily commerce. Without oil everything stops. The roots of our oil addiction can be traced back to the end of the 19th century, when petroleum began to be pumped from wells across America. It wasnt long before it become obvious what a great transport fuel it could provide. Oil-based fuels paved the way for intensive farming and extensive road networks; they drove the influx of populations into cities, drove growth in shipping and eventually made mass air travel possible. Oil has shaped our civilisation. Without crude oil youd have no cars, no shipping, no planes, says Gideon Samid, head of the Innovation Appraisal Group (IAG) at Case Western Reserve University in Ohio. And its not just about fuels. A giant chemical industry relies on oil as its feedstock, and without it many of the products we now take for granted would vanish. Youd see no plastics, no bags, no toys, no cases on TVs, computers or radios. Its absolutely everywhere, says Samid. Much of the economic expansion and growth of the human population in the 20th century is directly tied to the availability of large amounts of cheap oil, says Cutler Cleveland, director of the Center for Energy and Environmental Studies at Boston University. There isnt a single good or service consumed on the planet, except in rural economies, that doesnt have oil embedded in it. Oil is the lifeblood of the global economy. The secret of oils success is its portability and extraordinarily high energy density. One barrel of oil contains the energy equivalent of 46 US gallons of gasoline; burn it and it will release more than 6 billion joules of heat energy, equivalent to the amount of energy expended by five agricultural labourers working 12-hour days non-stop for a year. The vast majority of oil is consumed by transport. In the US, that sector accounts for nearly 70 per cent of the 20.7 million barrels the country gets through each day.. More than half of the worlds oil comes from seven countries, the leading supplier being Saudi Arabia, which produces more than 10 million barrels a day. Then come Russia, the US, Iran, China, Mexico and Canada. Twenty years ago, there were 15 oilfields able to supply 1 million barrels a day. Now, there are only four. The largest is the Ghawar field in Saudi Arabia. The IEA, which advises 27 countries on oil emergencies, requires its members to hold at least 90 days worth of fuel, which can be pooled and released onto the market if a crisis looms. The system last swung into action in 2005 when hurricane Katrina caused the shutdown of more than 23 per cent of the USs oil production capacity. A few days after Katrina struck, the IEA ordered the release of 2 million barrels a day from reserve stocks for a month, the first time reserves had been released since the Gulf war in 1991. About half the worlds oil is distributed by tankers mainly plying a handful of key routes across the oceans. The rest goes through an extensive network of pipelines that can carry different grades of crude and synthetic compounds, such as lubricants. The bewildering complex of pipelines - extending 90,000 kilometres in the US alone - crosses continents and dips under oceans. The pipelines are often above ground and vulnerable to accidental damage or attacks by saboteurs. When working, however, they provide an extremely efficient way of transporting oil. A pipeline that pumps a relatively modest 150,000 barrels per day delivers the equivalent of 750 oil tanker truck loads or one delivery every 2 minutes, day and night. Even if a pipeline is damaged, it can usually be quickly repaired. Valves at intervals along the pipe can isolate the leak while the damaged section is replaced. Disruption can still be costly. A report in 2005 by a US House of Representatives subcommittee on terrorism reported that sabotage to oil pipelines in Iraq had cost the country more than $10 billion in lost revenues, even though protection had been a high priority for the coalition troops since they invaded two years before. The report suggested that groups hostile to the US and its allies were becoming increasingly expert at mounting these attacks. Choke points Even outside a conflict zone, accidents can cause serious disruption. Last year, the IEA was on standby to release reserves after an explosion in Minnesota shut down part of the 5000-kilometre Enbridge pipeline, which pumps 1.9 million barrels of crude a day from Canada to the US Midwest. This single incident halted one-fifth of US oil imports for days. Oil deliveries by sea are vulnerable too. A fleet of 4000 tankers plying six main routes delivers more than 43 million barrels of oil every day. Many of these routes pass through narrow choke points, and if any of these were to become impassable, even temporarily, the effect on oil supplies could be dramatic. For instance, more than 16 million barrels of oil a day are shipped through the Strait of Hormuz, at the mouth of the Persian Gulf, taking oil from Saudi Arabia, Iran, Iraq, Kuwait, Qatar and the United Arab Emirates to the US, western Europe and Asia. At its narrowest point, the strait is only 33 kilometres wide. If necessary, some of Saudi Arabias exports could be diverted through the 1200-kilometre East-West pipeline to the Red Sea, but its maximum capacity is only 5 million barrels a day, half of which is already taken up. Between 1984 and 1987, during the Iran-Iraq war, both countries attacked tankers in the Strait of Hormuz, causing shipping to drop by 25 per cent. In 2003, the Bush administration claimed it had prevented further attacks on shipping in the strait. Another pinch point occurs in the Strait of Malacca, which narrows to just 2.7 kilometres between Sumatra and Singapore. Tankers from the Persian Gulf and west Africa transport some 15 million barrels a day through the strait en route to Japan, China and other Pacific destinations. A report by Luft claims that some tankers have been hijacked here by would-be terrorists whose initial aim has been simply to learn how to operate them. In 2003 a small chemical tanker called Dewi Madrim was taken over by 10 armed men, who sailed it through the strait before leaving with equipment and technical documents. One scenario being suggested is that hijackers might commandeer a liquid natural gas tanker plying one of these shipping routes, load it with explosives and use it to ram an oil tanker. If this floating bomb produced a burning oil slick, it could render the passage impassable for months, tipping the global economy into crisis as alternative routes would fail to make up the lost supplies. Another key element in the global oil infrastructure is Abqaiq, an enormous processing facility in Saudi Arabia, which removes sulphur from two-thirds of the countrys crude. The CIA estimates that seven months after a large-scale attack, output would still be only 40 per cent of its full capacity. More than half the oil from Abqaiq is pumped to the largest offshore oil terminal in the world, Ras Tanura on the Persian Gulf, which handles one-tenth of the worlds oil. This makes it a prime target for attack, and the site is as heavily defended as a military base. If you have a facility like this and a plane crashed into it, or terrorists get in and somehow succeed in blowing it up, then you have a very, very significant disruption on your hands. That is what analysts see as a doomsday scenario, Lufts says. Reuters reported that one planned attack on the terminal was thwarted in 2006. Saudi oil production is particularly vulnerable because it is concentrated in a few massive production and distribution sites. If one or two of these facilities goes down, then the entire system goes down, says Luft. So what would the impact be if oil supplies choked? In 2005, a group of current and former US government and national security officials were asked to address this in a live role-play exercise. Playing the part of the national security adviser was Robert Gates, who the following year became Secretary of Defense. The scenarios that unfolded were developed with officials from the Shell oil company in the Netherlands, a former US presidential counter-terrorism adviser and industry analysts. The simulation kicked off with an upsurge of political violence in Nigeria, the fifth-largest supplier of oil to the US. In the ensuing turmoil 600,000 barrels of oil production a day were lost from the Niger delta. The violence coincided with the start of a cold winter in the northern hemisphere, which increased demand by 700,000 barrels a day. Together, these events boosted the price of a barrel of oil from $58 to $82; a proportional rise today would push the price beyond $195. Events began to gather pace when, a month later, the simulation threw in an attack on the Haradh natural-gas processing plant in Saudi Arabia, which forced the country to cut 250,000 barrels per day from its exports - equivalent to the oil consumed every day in Switzerland - to meet domestic needs. Next, news arrived of an attempt to ram a hijacked supertanker into another vessel moored at a jetty at Ras Tanura. This was closely followed by a similar attack at the oil port of Valdez in Alaska, as well as a ground attack which set fuel depots alight. With the world oil shortfall now at 3.4 million barrels per day, the price per barrel had shot up to $123. Against the recent peak price of $139, that rise would take the cost per barrel to $295. The turmoil leads to an aggressive crackdown on anti-western groups and their sympathisers, which temporarily quells further attacks. Then, six months into the simulation, a terrorist campaign is launched against foreign workers in Saudi Arabia, killing 200 and wounding 250 within 48 hours. Evacuation of foreign workers follows. Though oil production continues unchecked, this loss of expertise leaves Saudi Arabia unable to meet future demand and with no spare capacity. Fears that this could lead to shortages in the future bring speculators into the market, and the price per barrel rises to $161. At the end of the simulation, global production has fallen by 3.5 million barrels a day, or 4 per cent of world oil supplies. One of the participants, Jim Woolsey, a former head of the CIA, described the scenarios as relatively mild compared to what is possible, yet this proved enough to almost triple the price of a barrel of crude. The key conclusion being drawn from this scenario is how reliant the global oil market is on Saudi Arabias ability to ramp up production on demand. If this extra oil is not available, the price rockets. Saudi Arabias recent reluctance to increase production and the ensuing price rises in todays real-life oil market amply bear out this prediction. So where does this leave us at a time when global oil production is approaching the point when it stops growing and starts to decline? Most industry experts, including geoscientists and economists, who were polled by Samid in 2007 said that peak production will occur by 2010. This contrasted with a similar survey conducted two years earlier, in which respondents were split, with many of the economists opting for a later date. Now, a real consensus is emerging, says Samid. This tells us that we will have to start making serious attempts to wean ourselves off oil, and fast. It will be no easy task. Its hardly conceivable that the world could function without oil, says Didier Houssin, director of oil markets and emergency preparedness at the IEA. Finding a replacement fuel for transport is the biggest challenge. So far all the alternatives have hit the skids. For example, hydrogen, which could potentially replace oil as a green fuel if made using renewable sources of energy, has storage and distribution problems. While biofuels, which could be an easier replacement for fossil fuels, require feedstocks that compete with food crops for water and agricultural land. To get these alternatives close to what oil can do, you have to invest a lot of money, says Cleveland, something most governments and energy companies have done reluctantly, and at pathetically low levels. These arent insurmountable problems, but they suggest the transition has some formidable challenges, he adds. One way or another oil will become more scarce, even more costly and will always have the disadvantage of generating carbon dioxide when its burned. However hard it may be, the sooner we make the break, the better. ~~~~~~~~ By Ian Sample Ian Sample is science correspondent for The Guardian newspaper in London 标签： 翻译 , 能源
小红猪小分队 发表于2008-01-8 星期二 3:15 分类: 小红猪翻译小分队 , 翻译 | | 原文来自《纽约客》，2008年6月2日，链接 http://www.newyorker.com/arts/critics/skyline/2008/06/02/080602crsk_skyline_goldberger photo: The steel lattice surrounding the Beijing National Stadium looks likea giganitic sculpture, but most of the beams are structural, not decorative. Photograph by Iwan Baan. To understand just how important the Beijing Olympics are to China, you have only to look at where the Olympic Green has been built. During Beijings first building boomsix hundred years before the current onethe city was laid out symmetrically on either side of a north-south axis. As in Pariswhere the Louvre lines up with the Tuileries, the Arc de Triomphe, and the Champs-lysesBeijings most symbolically important structures have fallen along the main axis. In the center is the former imperial residence of the Forbidden City. North of this is the Jingshan, a park surrounding an artificial hill where the last Ming emperor is said to have hanged himself, and, beyond that, the Drum Tower and the Bell Tower, which for centuries helped Beijings inhabitants tell the time. In 1958, when the Communists expanded Tiananmen Square, at the southern gate of the Forbidden City, they placed the Monument to the Peoples Heroes on the same axis, in the center of the square. Mao Zedongs mausoleum, also in the square, is on the axis, too. And now, spread over twenty-eight hundred acres at the opposite end of the axis, is Beijings Olympic Green. If Tiananmen Square is a monument to the Maoist policy of self-sufficiency, the Olympic Green, ten miles and fifty years away, is an architectural statement of intent every bit as cleara testament to the global ambitions of the worlds fastest-growing major economy. At least two of the buildings on the Olympic Greenthe National Stadium, by the Swiss architects Jacques Herzog and Pierre de Meuron, and the National Aquatics Center, by the Australian firm PTW Architectsare as innovative as any architecture on the planet, marvels of imagination and engineering that few countries would have the nerve or the money to attempt. The Chinese, right now, have plenty of both. These buildings, some of the most advanced in the world, are made possible partly by the presence of huge numbers of low-paid migrant workers. When I visited the stadium with Linxi Dong, the architect who heads Herzog and de Meurons Beijing office, he told me that the construction crew for his project numbered nine thousand at its peak. The National Stadium is already widely known by an apt nickname, the Birds Nest. The concrete wall of the arena is wrapped with a latticework exterior of crisscrossing columns and beams, a tangle of twisting steel twigs. The lattice arcs upward and inward over the stadiums seats (there are ninety-one thousand), supporting a translucent roof and forming an oculus around the track. The center of the roof, over the field, has been left open. The engineering required to keep all this metal in the air is highly sophisticated: the building may look like a huge steel sculpture, but most of the beams are structural, not decorative. The drama of the Birds Nest is even more arresting than that of the Allianz Arena, the Munich soccer stadium, which Herzog and de Meuron sheathed entirely in billows of translucent plastic, in 2005. Much of the spectacle derives from the interplay of the steel lattice and the concrete shell underneath. The outer wall of the concrete structure is painted bright redone of the buildings few overtly nationalistic touchesand when lit up at night it shines through the latticework, an enormous red egg glowing inside its nest. On leaving, you experience the excitement of the knotted metal in a new way, looking out over Beijing through the wacky frame of the slanting columns. Next door to the Birds Nest is the Aquatics Center, known as the Water Cube, a rectilinear building with a blue-gray exterior of translucent plastic pillows set in an irregular pattern intended to evoke bubbles. John Pauline, who is the head of the Beijing office of PTW Architects, told me that the design emerged from a desire to find a way of expressing the feeling of water. We started out with ripples and waves and steam, he said. We basically looked at every state of water we could imagine. And then we hit on the idea of foam. Working with the engineering firm Arup, which also collaborated on the Birds Nest, PTW developed cladding made of variously sized cells of ETFE, or ethylene tetrafluoroethylene, a translucent plastic somewhat similar to Teflon. Among architects, ETFE is the material of the momentHerzog and de Meuron used it for the faade of their Munich stadium and for the roof of the Birds Nestand it has many practical virtues. It weighs only one per cent as much as glass, transmits light more effectively, and is a better insulator, resulting in a thirty-per-cent saving in energy costs. Furthermore, the pillows dont just evoke bubbles; they are bubbles, twin films of ETFE, eight one-thousandths of an inch thick, placed together to form a cell, which is then inflated. The real achievement of the Water Cube is less its technical wizardry than the transformation of the faintly trite idea of a bubble building into a piece of elegant, enigmatic architecture. The architects decided that, to play off the oval shape of the Birds Nest, the Aquatics Center would have to be square, and the constraint of straight lines seems to have insured that the bubble metaphor didnt get out of hand. The Water Cubes walls suggest the soap foam on a shower dooror perhaps, since some of the bubbles are as much as twenty-four feet across, on the slide of a microscope. From the outside, the almost random arrangement of cells establishes a kind of correspondence with the irregular struts of the Birds Nest. When you are inside the main hall of the Water Cube, the pattern of cells above and the green-blue tinge of the pool give you the feeling of being under water yourself and looking up toward the surface. Although Chinas burgeoning wealth owes much to its export industries, for the Olympics the country has been content to play the reverse role, buying the most futuristic architecture that the rest of the world has to offer, rather than showcasing native talent. The work of Chinese architects has largely been relegated to a jumble of functional but uninspiring buildings. (There are thirty-one Olympic venues in all.) An important exception is Digital Beijing, a control center on the Olympic Green, designed by a Chinese firm, Studio Pei Zhu. Like the Water Cube, Digital Beijing steers dangerously close to a kitschy conceit. It consists of four narrow slabs set close together in parallel to resemble a row of microchips or, perhaps, hard drives. Some of the walls have glass cutouts in a linear pattern clearly designed to evoke a circuit boardthey light up green at night. Yet the finished building has a dignity that is surprising. This is due in part to Pei Zhus choice of materialsthe walls are clad in a sober grayish stoneand in part to the proportions of the four slabs, whose narrowness and lack of adornment give the building an austerity that is the opposite of kitsch. Pei Zhu may be Chinese, but his building is thoroughly international in style. (He was educated at the University of California and has worked both in China and abroad.) Indeed, apart from the red of the Birds Nest, there is little that is traditionally Chinese in any of the Olympic developments. The scale and ambition of the project is an unmistakable statement of national pride, yet China, strangely, has been content to make this statement using the vocabulary of the kind of international luxury-modernism that you might just as easily see in Dubai or SoHo or Stuttgartdizzyingly complex computer-generated designs, gorgeously realized in fashionable materials. The message seems clear: anything you can do, we can do better. The first Olympic Games of the modern era, in 1896, were held in an ancient stadium in Athens that the Greeks refurbished for the occasion. The swimming events took place in the Aegean Sea. The next Olympics, in Paris in 1900, had no stadium at all. The track-and-field competitions were held on the streets of the city and on the grass of the Bois de Boulogne, which the French did not want to disfigure with a proper track. Swimmers were left to cope with the currents of the Seine. The idea that cities could attract the Olympics by promising lavish facilities probably began after 1906, when the eruption of Mt. Vesuvius put an end to a plan to have the 1908 Games in Rome. The British saw Italys misfortune as an opportunity and offered to build a stadium big enough to hold a hundred and fifty thousand people, in Shepherds Bush, London. The White City Stadium, as it was called, was the first stadium to be erected specifically for the Olympics. Soon, countries were openly vying with one another to host the Games. (What is the Olympic ideal, after all, but national rivalry dressed up as global amity?) The apogee of triumphalism was reached, notoriously, in Berlin, in 1936, when Hitler, who wasnt yet in power when the Games were awarded to the city, embraced the Olympics as the way to show off the might of the Nazi regime. Architecture was as much a part of his vision as the gold medals, though his taste ran to the turgid and overblown. He tore down a perfectly good, barely used stadium, replaced it with the largest stadium in the world, and then built a hundred-and-thirty-acre Olympic Village, with a hundred and forty buildings laid out in the shape of a map of Germany. Since the Second World War, host countries have avoided such bombastic excess, but they have usually seen the Olympics as an opportunity to pin a gold medal on one or more of their leading architects. There was Pier Luigi Nervis innovative, seemingly floating concrete dome on his stadium for the Rome Olympics, in 1960; Kenzo Tanges swooping, sculptural gymnasium for Tokyo, in 1964; Gnter Behnisch and Frei Ottos canopied stadium for Munich, in 1972. For the Barcelona Olympics, in 1992, the Spanish architect Santiago Calatrava was enlisted to build a communications tower that would serve as an Olympic symbol. Calatravas angular, precarious-looking design, inspired by an arm holding the Olympic torch, established his world-wide reputation and remains one of the citys most visible structures. But the Barcelona Olympics also marked a new approach to Olympic architecture, one that placed as much emphasis on the relationship between the city and its facilities as on the sports venues themselves. Barcelona used the Games as an occasion to redevelop its waterfront and design a series of new parks, fountains, and works of public art to attract tourists after the Games were over. Since then, cities have been keen to use the Olympics to leverage other civic improvements, on the premise that if youre spending billions to refurbish a city you should at least invest in buildings that have long-term utility. Thats why the legacy of the 1996 Olympics, in Atlanta, isnt any of the athletic buildings but a major new park and housing for athletes that became new dormitories for Georgia Tech. The plan for the 2012 Olympics, in London, takes this idea a step further. Although there is one flashy commission for a British architect (an aquatics center, designed by Zaha Hadid, in the form of a giant wave), the London Olympics are distinctly short on architectural extravaganzas. The main stadium, to be designed by a large American firm that has had a lock on football and baseball stadiums for years, will be dull compared to the Birds Nest. When I talked to Ricky Burdett, a professor of architecture and urbanism at the London School of Economics, who is an adviser to the London Olympics, he told me that London did not feel the need to prove itself through spectacular works of Olympic architecture. We had a big debate over whether we should build a new stadium at all, he said. We were much more interested in how an intervention on this scale will affect a city socially and culturally. The British government plans to invest roughly nineteen billion dollars in an Olympic site, in the East End of London. When the Olympics end, much of the area will become a park, and sales of private development sites around it are expected to enable the government to recoup much of its investment. Burdett said, London has always been poor in the east and rich in the west. The London Olympics can rebalance London. Beijing, evidently, has other priorities. For all the sleek modernity of much of the construction, theres no mistaking the old-fashioned monumentalist approach behind it. This is an Olympics driven by image, not by sensitive urban planning. Its true that there has been a much needed and well-executed expansion of Beijings subway system, but most of the impact of the Olympics has been cosmeticthe trees planted along the expressway to the airport, for example, or the cleanup of some of the roadways leading to the Olympic Green. Bordering one stretch of congested elevated ring road, stone walls, like the ones surrounding the old Beijing hutongs , or alleyway neighborhoods, have been erected. But, with not much behind them, they are little more than a stage setPotemkin hutongs designed to distract visitors from the fact that so many real hutongs are being demolished for high-rise construction. In todays Beijing, forcible eviction is common, and hundreds of thousands of people have been displaced to make way for the Olympics. The brightness of the Olympic halo gives Beijings relentless expansion a surface sheen, but its only a distraction from the citys deeper planning problems, such as air and water pollution and overcrowding. In general, the Chinese authorities have been less interested in solving these problems than in keeping the construction engine going at full throttle. Still, the Olympic site did require some planning and, in 2002, a competition was held to create a master plan. It attracted entries from ninety-six architects around the world, and was won by a Boston firm, Sasaki Associates. Despite its straight-line connection to the Forbidden City, the Olympic Green lies in a district that, in recent years, has become a forest of undistinguished high-rise apartment buildings and commercial towers. (The site also includes a mundane athletic compound erected for the 1985 Asian Games, and these leftover structures are all being refurbished for the Olympics.) Dennis Pieprz, the president of Sasaki, who was in charge of the scheme, explained to me that the firm struggled for a long time with the question of how to treat Beijings axis. The Chinese tradition of aligning important public buildings created a huge temptation to put the stadium right on the axis, he said. But we decided that in the twenty-first century we were beyond that, and that we should, instead, symbolize infinity, and the idea of the people in the center, not a building. So Sasaki placed the stadium just to the east of the axis and the Water Cube just to the west; the space directly on the axis was left open. Pieprz told me that he felt that considering the long-term use of the site was essential. We needed a plan that could accept other civic, cultural, recreational, and commercial uses, so the place would become a major destination, he said. Sasaki envisions the Olympic site as becoming a large park, with each of the major buildings taking on a public function. The Birds Nest will remain as the national stadium, its capacity reduced to a more practical eighty thousand by the removal of several tiers of seats; the Water Cube will lose almost two-thirds of its seventeen thousand seats, the upper tiers to be replaced by multipurpose rooms. You are making a city, not a spatial extravaganza that will be interesting just for sixteen days, Pieprz said. But, whatever the architects feel, its not clear that the Chinese are really that interested in long-term uses. The focus is on August, and on confirming before the world Beijings status as a modern, global city. However well the buildings are refitted afterward, its hard to see how the Olympic park will relate to the rest of the city, beyond being a welcome piece of green space in an increasingly built-up, sprawling metropolis. The success of what China has built for the Olympics will ultimately be measured not by how these buildings look during the Games but by the kind of change they bring about in the city. The billions of dollars spent on the Olympic site, after all, are only a fraction of the money that has been invested in construction in Beijing since the Games were awarded to the city, in 2001. The city, however, has yet to build a public space as inventive as that of post-Olympics Barcelona, or to think of the impact of the Olympics in terms as sophisticated as pre-Olympics London. In both conception and execution, the best of Beijings Olympic architecture is unimpeachably brilliant. But the development also exemplifies traitsthe reckless embrace of the fashionable and the global, the authoritarian planning heedless of human costthat are elsewhere denaturing, even destroying, the fabric of the city. 标签： 小红猪 , 建筑 , 翻译
小红猪小分队 发表于2008-01-8 星期二 12:57 分类: 小红猪翻译小分队 , 翻译 | | 原文链接： http://www.newscientist.com/channel/being-human/mg19926681.500-why-complex-systems-do-better-without-us.html Sometimes life runs more smoothly when you stop trying to control it. Mark Buchanan goes with the flow Why complex systems do better without us ●WE HUMANS prefer the tidy to the untidy, the ordered to the disordered. We like pristine geometrical regularity, and eschew what is erratic and irregular. We want predictability and, more than anything, we want control. In these confusing times, it might seem as if we have little power over anything. Instead of letting it get us down, though, perhaps we should take comfort from the work of Dirk Helbing , a physicist at the Swiss Federal Institute of Technology (ETH) in Zurich. Helbing has been studying the movement of tens of thousands of cars on road networks; the workings of vast webs of interacting machines on factory floors; and other systems, where the complexity of what happens and why routinely defeats the human mind. What Helbing and others are finding is that our penchant for regularity and control is seriously misguided. In many situations they are discovering that it is better to give up some of our control and let systems find their own solutions. Often the answers turn out to be unlike anything our minds would imagine, yet the outcomes are far more efficient. The findings come as something of a relief to todays engineers, who are increasingly dealing with problems too complicated for them to solve. Take one of the earliest successes chalked up by machines allowed to take control. Back in 1992, General Motors were having trouble managing the automated painting of trucks at an assembly plant in Fort Wayne, Indiana. Machines in 10 different paint booths could paint trucks as they came off the line, but because the trucks came off in an unpredictable order and the painting machines needed sporadic maintenance and repair, finding an efficient assignment of trucks to booths seemed impossible. General Motors visionary engineer Dick Morley suggested letting the painting machines find a schedule themselves. He set out some simple rules by which the various machines would bid for newly available paint jobs, trying their best to stay busy while taking account of the need for maintenance and so on. The results were remarkable, if a little weird. The system saved General Motors more than $1 million each year in paint alone. Yet the line ran to a schedule that no one could predict, made up on the fly by the machines themselves as they responded to emerging needs. Production processes generally depend on so many inputs, parameters and factors that even small changes in the set-up can lead to wildly different and unpredictable consequences. That is why it is almost impossible to predict what will happen in a new production line based on previous experience. Managers sometimes take performance in past set-ups and try to estimate what will happen in a new setting by interpolation, says Helbing. This often gives very bad results. To cope, he says, engineers need a healthy respect for the complex unpredictability of these systems and how natural human inclinations often lead to undesirable outcomes. You cant steer these things like you can a bus, says Helbing. You have to learn to use the systems own self-organising tendencies to your advantage. Helbing has come to this view by an unusual path. Though he trained as a physicist, he became fascinated in the early 1990s by parallels between physics and human movements. I was inspired by the similarity between fluid flows and how people walk around obstacles, he recalls. For nearly two decades, he and colleagues have been studying the mathematics of collective human motion, which explains why Helbing now holds a chair in sociology. Social scientists usually focus on the variability of human behaviour, which is hard to predict. But Helbing argues that in many cases it isnt very important. Thats because circumstances often constrain peoples options so much that humans respond almost automatically to external forces, making their average behaviour predictable. On the roads, for instance, people generally drive close to or just over the speed limit, similar to the way self-propelled particles repel one another when they get too close. Although the behaviour of individuals is often simple, the collective patterns to which it leads can be counter-intuitive, making common sense a faulty guide to what might happen. For example, it is generally true that traffic jams become more likely as traffic density increases. Its not always the case, though, as Helbings group has shown. Consider a two-lane road carrying both cars and trucks, where the cars are moving faster on average. At low traffic densities, the cars have plenty of space to overtake and can easily pass the trucks. As the traffic density increases, drivers find it more difficult to overtake because other vehicles are in the way. However, evidence from simulations and real traffic flows shows that at a critical density of traffic, the obstruction to lane-changing begins to have a beneficial effect. Because drivers tend to stay in one lane, they disturb the flow of traffic less, leading to a higher total throughput of vehicles. Similar counter-intuitive results show up in crowds of people. In simulations and experiments, Helbings team has confirmed what they call the slower-is-faster effect. When people try to escape from a room through a doorway, more get out if everyone stops rushing as this prevents obstructions. Surprisingly, it turns out that placing an obstacle in front of the door can actually enable people to get out faster, as it helps to regulate the flow of people and maintain its fluidity. A suitable obstacle can improve the outflow by about 30 to 40 per cent, says Helbing. What makes it work is that crowds adjust to local conditions. When two streams of people meet at either end of a narrow passage, you might expect a jam to form as only a chaotic trickle of people pass through. But in real life, people often do something completely different: they organise so that a group goes through first in one direction and then the other, as long as the density isnt too high. The crowd organises itself spontaneously to a better outcome. Helbing has found that you can model crowds using ideas akin to those from physics. As a queue grows on one side of the passage, it produces something resembling the pressure of a fluid or a gas. A high density of people pressing together ultimately acts to drive people through the opening, thereby relieving the pressure. Further work has convinced him that systems involving pedestrians, traffic and products flowing through factories often work in surprisingly similar ways, hence lessons learned about one may also apply to another. Last year, Helbing and Stefan Lammer at the Technical University of Dresden in Germany began wondering if traffic lights could also be engineered to cut congestion. According to a report by David Shrank and Tim Lomax at the Texas A M University in College Station, congestion in the US alone costs an estimated $78.2 billion, wastes 4.2 billion hours in delays and 10.9 billion litres of fuel. So the potential impact of efficient traffic flow could be huge. This would mean giving traffic lights a way to adapt their behaviour, which most of todays systems lack. At the moment, engineers force traffic into patterns that appear favourable. Lights on main roads stay green longer during peak hours, for example. But its the engineers who do this tuning based on average conditions observed in the past; most traffic lights dont have the flexibility to respond to changing conditions on their own. Engineers also take some things for granted, such as the notion that lights must be managed from a central control. Lights can do a better job, Helbing and Lammer have found, if they are given some simple operating rules and left to organize their own solution. To demonstrate this, they developed a mathematical model that assumed traffic flowed like a fluid, a wellestablished traffic engineering technique. The model also describes what happens at road intersections, where traffic entering from one road has to leave by another, much like fluid moving through a network of pipes. Of course, jams can arise if traffic entering a road overloads its capacity. To avoid this, Helbing and Lammer make the lights at each intersection respond to growing traffic pressure, like the people going through the passage. Each set of lights carries sensors that feed information about the traffic conditions at a given moment into a computer, which then calculates the flow of vehicles expected in the near future. The computer also works out how long the lights should stay green in order to clear the road and relieve the pressure. In this way, each set of lights can estimate for itself how best to adapt to the conditions expected at the next moment. Best left alone This isnt enough, however, because the lights might adapt too much. If they are only adapting to conditions locally, they might cause trouble further away. To avoid this, Helbing and Lammer have devised a scheme whereby neighbouring lights share their information so that what happens around one traffic light can affect how others respond. By doing so, the self-organised lights prevent long jams from forming. Despite the simplicity of these rules, they seem to work remarkably well. Helbing and Lammer have demonstrated in simulations that lights operating this way should achieve a significant reduction in overall travel times and keep no one waiting at a light too long (See diagram, below 等你们抢到了我再给你看图吧不会贴。 ). Nonetheless, the behaviour of the lights doesnt generally fit with human notions of what ought to be efficient. How long lights stay green is unpredictable, says Lammer. Yet the average journey times go down and become more predictable. Whats more, the scheme eliminates other irritating problems that afflict traditional traffic control. At quiet times, drivers typically have to wait far longer than is really necessary at intersections because the lights schedules are designed to serve a large number of vehicles. And in the middle of the night, lights keep stopping cars even when there is no need. The self-organising traffic scheme eliminates these problems because the lights remain responsive to local demands, for instance sensing an approaching car and changing to green to let it through. Town planners are beginning to look at self-organising lights as a practical solution to looming traffic congestion. Helbing and Lammer are working with a local traffic agency in Dresden, Germany, first to test and then hopefully to implement the idea. In early simulations based on Dresdens road layout, they have had encouraging results. Weve found significant reductions in waiting times and fuel consumption, and we can also accelerate public transport, says Lammer. Authorities in Zurich, Switzerland, have also been taken by the idea. Yet Helbing and Lammer suggest their scheme only begins to illustrate the potential for self-organised traffic flow. The technology to make cars also sense and respond to local conditions already exists, and many of us may soon cede at least some control of our car to on-board guidance systems. If cars can talk to one another, Helbing and his colleagues have shown, they could improve traffic conditions even more greatly reducing the severity of jams at times and possibly even eliminating them altogether (see Cruise Control, below). The wider lesson is that we just cant trust our intuition when it comes to the supercomplex systems that we depend on today. We may never learn exactly how to control these systems in the traditional fashion and the best way to cope may be by learning new principles for letting them manage themselves. Engineering isnt just about solving problems any more, but building systems that can solve their own problems. Being in control, it seems, may increasingly demand being a little out of control. ●Mark Buchanans latest book is The Social Atom (Cyan Books, 2007) Further Reading: Self-control of traffic lights and vehicle flows in urban road networks by Stefan L 鋗 mer and Dirk Helbing, www.arxiv.org/abs/0802.0403 Cruise Control Some of todays cars already contain technology that lets a driver hand over some control to on-board devices. Unlike conventional cruise control, which simply maintains a drivers chosen speed, adaptive cruise control (ACC) uses radar to sense the distance and speed of the car in front. By updating that information several times a second, the system maintains the cars speed and separation distance and automatically brakes if the car in front slows down, or accelerates when the leading vehicle does. Also, it responds faster and more accurately than human reflexes. In recent simulations, engineer Arne Kesting at the Technical University of Dresden in Germany, working with Dirk Helbing at the Swiss Federal Institute for Technology in Zurich and others, have studied how the technology might help traffic respond to emerging problems. While it may be some time before most automobiles on the highway are fitted with adaptive cruise control, the researchers have shown that even a small fraction of users could make a huge difference. At the moment, drivers can respond only to conditions they encounter or perhaps hear about on radio reports. ACC cars could easily be fitted with sensors able to receive signals conveying local traffic conditions from roadside monitors or other cars. Kesting and his colleagues suggest that these signals could reduce congestion by making cars equipped with ACC drive more intelligently. For instance, cars flowing out of a traffic jam could automatically drive closer together in order to clear the jam faster. Meanwhile, cars approaching the jam would slow more gradually, rather than brake abruptly when reaching it. This would maintain greater fluidity in the traffic, improving road capacity and stability of traffic flow. Kestings simulations suggest that if 25 per cent of the cars were using ACC, the scheme could eliminate many traffic jams. Even if only 3 per cent of the cars were equipped, travel times could be significantly reduced. Kesting and Helbing are currently testing these ideas with Volkswagen and hope to see the scheme on real roads in a few years. 标签： 翻译
小红猪小分队 发表于2008-08-21 星期四 10:27 分类: 健康 , 医学 , 小红猪翻译小分队 | | 包皮环切术的真专家和假内行之间展开唇枪舌战。薇薇安 马克斯进行深度调查。 署名人：薇薇安 马克斯，格拉汉 劳顿； 译：BY 【 科学松鼠会 之 小红猪小分队 出品，非商业转载请注明出处】 设想一下，存在某种快捷简单的外科手术，实验结果表明，它能给你新出生的孩子终生 HIV 防御能力，也许还能抵挡各色性传播疾病，甚至癌症。这手术只有轻微的疼痛，少量的流血，偶尔会出岔子，但出现严重反作用的风险微乎其微。你是否会选择它？我猜你多半会。可是，等你发现其他实验的结果认为这项手术的益处很有问题，而且它还牵涉到切掉你孩子阴茎的一部分，这时候你又做何种感想呢？ 简单来说，这正是新生男孩父母所面临的两难问题。据风头越来越劲的男性包皮环切术鼓吹者说，切掉一截包皮是有史以来最有效的公众卫生手段之一，应该像疫苗接种一样成为常规。反对者则说，且慢。反对者坚称环切术并无医学上的好处，而且还要毁坏男人的性生活。类似的争论持续了几十年，但近期就环切术在阻止 HIV 传播中扮演的角色方面的发现，让包皮或是没有包皮又回到了公众卫生的议事日程中。 据伦敦卫生学和热带医学学院（ London School of Hygiene Tropical Medicine ）的海伦 维斯（ Helen Weiss ）说，全世界有大约百分之三十的男人做过环切术，因而环切术很可能是地球上最普遍的外科手术。大多数环切术的原因是文化和信仰，不过在医学领域内推广此项手术以提高卫生和防止感染也已有时日。 环切术鼓吹者的最新发现是防止 HIV 感染。二十世纪八十年代中期，美国泌尿学家阿隆 芬克（ Aaron Fink ）注意到非洲 AIDS 患者中有很大一部分没有做过环切术（ The New England Journal of Medicine , vol 315, p 1167 ）。在接下来的几年中，成堆的实测证据表明，做过环切术的男人倾向于较低的 HIV 阳性概率，到两千年的时候，这项结果得到了广泛的接受（ AIDS , vol 14, p 2361 ）。 不过，我们所需要的是大量随机临床实验结果，以此证明环切术能保护男人对抗病毒。这方面的首个研究于二零零二年开始产出数据，实验地点为橙子农场（ Orange Fame ）南非靠近约翰内斯堡的大型城镇。照计划实验要进行三年之久，但被提前结束，因为半途分析表明环切术将 HIV 感染率降低了百分之六十这样的结果让实验的领导者，法国国立健康与医药研究院（ INSERM ）的贝尔特朗 奥夫列特（ Bertran Auvert ）把环切术比作效率极高的疫苗（ PLoS Medicine , vol 2, p e298 ）。 另外两次规模更大的实验，一次在肯尼亚的奇苏穆（ Kisumu ），另一次在乌干达的拉凯（ Rakai ），也都由于压倒性的正面结果而提前中止。这两项研究在《柳叶刀》杂志上登出时（ vol 369, p 643, and p 657 ），与之相配的编者按称之为 HIV 预防的新时代（ The Lancet , vol 369, p 615 ）。奥夫列特的计算认为，二零零六年到二零一六年之间，环切术在非洲撒哈拉以南地区内可以预防三百八十万起感染和五十万起死亡，到二零二六年可累计防止五百八十万起死亡（ PLoS Medicine , vol 3, p e262 ）。 环切术主要保护异性间性交中的男子，同时也惠及女性。美国国家过敏与传染病研究院（ US National Institute of Allergy and Infectious Diseases ）的安东尼 佛西（ Anthony Fauci ）他帮助奇苏穆和拉凯的实验筹集资金对此发表评论道，初期的好处是男性 HIV 感染者的减少，但环切术也能让那些 HIV 主要通过异性间性交传播的地区内的女性感染者减少。 说到这里，环切术究竟是如何抵御 HIV 的呢？据澳大利亚悉尼大学（ University of Sydney ）的分子生物学家，同时也是环切术的主要支持者，布莱恩 莫里斯（ Brian Morris ）解释，包皮内衬正是我们的弱点。病毒难以攻破包皮外表面的角质化皮肤和阴茎本身，但包皮内表面缺少角蛋白，并且堆积有大量 Lngerhans 这样被 HIV 当作进入点的的免疫细胞。这让包皮内衬变得非常，非常易受攻击，莫里斯如是说。 HIV 长驱直入。 非洲实验鼓励了世界卫生组织（ World Health Organization ）和联合国 HIV/AIDS 联合计划（ Joint United Nations Programme on HIV/AIDS ， UNAIDS ）进行规划，帮助非洲国家在成年男性中开展或是推广环切术不过他们也特别提请注意，环切术并不能让男性免疫，伴侣间依然应该进行安全性行为。这是进行预防的大好时机，特别是对于高 HIV 流行性的某些非洲地区而言，哈佛公众卫生学院（ Harvard School of Public Health ）的流行病学家，美国国际发展处（ US Agency for International Development ， USAID ）的前全球 HIV 顾问，丹尼尔 豪普林（ Daniel Halperin ）说。叫我说，这是二十年来最伟大的医学发现，旧金山市健康部门主持性传播疾病预防和控制事务的杰弗里 克劳思纳这样说。 然而，就环切术所涉及的各种事情而言，它们或许都没有初看时那般确定让我们先从实验本身说起。许多批评者认定实验的设计和执行导致了不确定性，环切术在真实世界中的有效性或许根本比不上基于实验结果的预测（ Future HIV Therapy , vol 2, p 193 ）。举例来说，众所周知，由于结果太好而过早结束的临床实验往往对有效性估计过高（ The Lancet , vol 368, p 1236 ）。很多研究者认为，如果实验做满三年而且一直继续下去的话，更多接受过环切术的男人可能被病毒感染。 法国巴黎巴斯德研究院（ Pasteur Institute ）的米切尔 加鲁涅认为，与此类似的各种因素使得环切术和疫苗之间的类比有着高度误导大众的可能性。十八个月内，百分之六十的减少，这和疫苗提供的近乎于百分之百的抵御能力迥然不同，更说不上在一生的性行为中保护男性个体（ PLoS Medicine , vol 3, p e78 ）。他还就对于研究结果的一般化提出异议，指出在某些国家首当其冲的是喀麦隆、莱索托和马拉维，事实恰恰相反（ African Journal of AIDS Research , vol 7, p 1 ）。 除此之外，对于环切术是否能够保护女性也颇有争议。在今年早些时候的一场重要 AIDS 研讨会上，马里兰州巴尔的摩市的约翰 霍普金斯大学（ Johns Hopkins University ）的小组报告，已经接受过环切术的男性，如果他们呈 HIV 阳性，那么其伴侣受感染的几率较高。据小组领导者玛丽亚 瓦沃（ Maria Wawer ）认为个中原因是一些伴侣在环切术伤口愈合之前，过早进行了性生活，这使得女性暴露在含病毒的血液之中。 当然了，环切术无法保护 HIV 阳性的男性，但如若环切术成为主流，这些男性恐怕也会去做环切手术：或许因为他们不知道已经已受感染，或许因为没有经过环切的阴茎将成为 HIV 阳性的标志。 另外一件要害怕的事情是，环切术可能会鼓励高危性行为，因为男性或会产生错误的安全感，甚至觉得自己拥有免疫力，可以停止使用安全套。奥夫列特的小组估计此项作用将使环切术的有效性从百分之六十降至百分之五十（ PLoS Medicine , vol 3, p e517 ）。另一模型的结果是，如果百分之四十接受过环切术的男性明显加强高危性行为频率的话，那么环切术的正面效果将被彻底抹杀（ International Journal of Epidemiology , DOI: 10.1093/ije/dyn038 ）。话虽如此，一项在肯尼亚进行的真实世界研究表明，新近接受过环切术的男性并没有更多进行高危性行为，例如不使用安全套（ Journal of Acquired Immune Deficiency Syndromes , vol 44, p 66 ）。 非洲进行环切术的争论持续之时，在西方世界又展开了第二场辩论。如果环切术在非洲成为了对抗 AIDS 的有效武器，那么是否应该在其他各处推而广之？ 双方都缺乏有足够说服力的证据。豪普林说，流行病学意义上的极大地域差异意味着无法直接将非洲的发现应用于其他地区。 举例来说，在非洲撒哈拉以南地区， HIV 传播的主要途径是异性间的性行为；但是在发达国家中，主要传播途径是男性间的同性性行为、卖淫和注射毒品。这让仅能保护异性间性行为中男性的措施的公众卫生价值变得疑问重重。更有甚者， HIV 在西方的流行程度远逊非洲，支配性的亚种是 HIV B ，而非 A 、 C 和 D 这些因素对环切术的效力有着未知的影响。关于西方 HIV 和环切术的观察研究为数不多，结果也莫衷一是（ PLoS Medicine , vol 4, p e223 ）。 去年，美国疾病控制与预防中心（ Centers for Disease Control and Prevention ， CDC ）对 HIV 的各个方面进行了论证，结论是没有足够理由在美国全境推广此项手术，但高危男性或可选择进行环切术。纽约市的健康管理部门也在考虑是否需要提倡环切术。 不过， HIV 还不是鼓吹者认为男孩应该进行常规性环切术的唯一原因。他们指出，大量且持续增加的证据群尽管多数尚存争议，而且没有任何一项源自随机受控实验说明，环切术能预防许多其他健康问题，这些问题从轻度泌尿系统感染到癌症林林总总，不一而足。 比方说，一些研究表明，接受过环切术的男孩罹患泌尿系统和肾脏感染的几率较低。其他研究发现未接受环切术的男人患性传播疾病的风险更高，这些疾病包括衣原体感染、生殖器疣、疱疹、淋病、梅毒和软下疳。环切术还能预防包皮过长包皮太紧，导致勃起和排尿疼痛；包皮过长也是阴茎癌的重要致病因素。环切术还能提供对于人乳头状瘤病毒（ HPV ）的防御能力，人乳头状瘤病毒也是阴茎癌的重要原因。一项最近的研究表明，未接受过环切术的男性罹患阴茎癌的可能性要高二十倍（ Journal of the American Academy of Dermatology , vol 54, p 369 ）。一些研究甚至证明，未接受过环切术的男性有着较高的性机能紊乱的比例。 总而言之，莫里斯说，每三名未接受过环切术的男性中就有一位迟早需要医疗介入，来解决通过环切术能够预防的问题。对各个年龄的人都有好处，他说。如果你没有接受过环切术，那么你就有了很大的公众卫生问题（ BioEssays , vol 29, p 1147 ）。也有惠及女性的健康益处。未接受过环切术的男性的女性性伙伴的子宫颈癌患病率略高，原因或许也是 HPV ，同时疱疹和衣原体感染的发生几率也较高。 好虽好，但医学权威依然不愿推广环切术。美国儿科学院（ American Academy of Pediatrics ）正在关注 HIV 相关的数据，但其当前的态度是，环切术的潜在益处还不足以让它成为常规手术。与此同时，英国医学联合会（ British Medical Association ）认为环切术的医学证据模棱两可。其他发达国家的权威也持有类似的态度。 如此谨慎态度的一大原因是手术并发症的风险。并发症多数都很轻微，例如流血、疼痛和麻醉的副作用。但并发症偶尔也会很严重：据记载有严重感染、外伤，甚至死亡的病例。并发症的原因无法枚举，这主要因为实施环切术的手术环境实在太不相同。 CDC 说，美国境内，百分之零点二到百分之二的环切术伴随有并发症，绝大多数都很轻微。 此种不确定性让环切术的相关成本和收益难以估算。举例来说，莫里斯认为对一千个男孩实施环切术就可预防一起阴茎癌，但别的研究却认为这个数字接近于三十万。 支持环切术的阵营近来风生水起，不过反对环切术的团体也有如雨后春笋，他们认为所谓的益处被过度放大，而风险则被过度低估。某些人认为对无自主能力的儿童进行环切术侵犯了他的人权。华盛顿州西雅图市，反对环切术医生会（ Doctors Opposing Circumcision ）的乔治 丹尼斯顿（ George Denniston ）说环切术是在男子身体重要部分进行的伤害性切除。 环切术支持者说，反对者的基石与其说是科学，不如说是迷信。圣迭戈加州大学（ University of California ）的性医学系系主任，欧文 戈德斯坦因（ Irwin Goldstein ）说，我觉得除了情感因素之外，根本没有证据能让人们说我们造成了伤害。 辩论牵涉到性爱时，往往变得喧闹无序，科学性上也混沌不清。据支持者说，环切术对男子性生活毫无影响，还能提升伴侣的感受。反对者的意见则彻底相反，他们说包皮是阴茎上的高度敏感部位，对于正常的性功能和行乐而言必不可少。说到这儿，科学也变得口齿不清。某些研究说接受过环切术的男性对于抚爱的感受性有所降低（ BJU International , vol 99, p 864 ）。不过，更多的研究，其中包括威廉 马斯特斯和维吉尼亚 约翰逊在其一九六六年经典著作《人类性反应》中所做的，认为阴茎感受性方面并无差别。近期的范例可见《性医学杂志》， vol 4, p 667 。 走出实验室，说法也一样互不相让。多数源自非科学性调查的信息倾向于证明论者成见。比方说，在一九八八年，环切术倡导者詹姆斯 巴吉尔（ James Badger ）说，在接受环切术前后都有过性行为的男子认为，接受之后的质量更高，而女人也认为接受过环切术的阴茎更有吸引力。可是，由环切术批评者克里斯藤 奥哈拉发现，女性压倒性地更喜欢纯天然的交媾（ BJU International, vol 83, p s79 ）。 性方面争论的最近一把柴由乌干达的环切术实验添加。约翰 霍普金斯大学的罗纳德 格雷（ Ronald Gray ）带领的小组比较了由超过两千名男性构成的两个组：一个组中的男性在两年研究期的开始做了环切手术，另外一个组中的男性则一直不做手术。当男人们被问及性欲、功能和满意度时，研究者发现并无明显差异（ BJU International , vol 101, p 65 ）。 我认为，我们需要更多关于环切术对阴茎感受性的影响的直接数据，印第安纳州布鲁明顿市，金赛研究院（ Kinsey Institute ）的埃里克 简森（ Erik Janssen ）说。是否能认为补充形式的性刺激更具快感？我觉得这个课题上没有做过真正好的研究；要是有人肯出资，我愿意做这个课题。 就现在而言，围绕环切术的争论还在持续升温，双方各有偏见和混淆。我们最需要的是来自随机受控实验的确切数据。科学家心胸开阔，莫里斯说。咱们十年以后再看，要是有证据说环切术并无必要，我保证欣然收手。 薇薇安 马克斯是居住于纽约的作者。 原文 见此 标签： 医学 , 翻译
（这是一篇旧文章，曾发在网上，未发表在报刊媒体上。） 达尔文自传的译本分析――以序言为例 查尔斯?达尔文（Charles Darwin，1809～1882）是世界上著名的生物学家，他的进化理论极大地影响了一百多年来世界的科学和社会思想的发展。达尔文的自传也是名人自传中的佳作，一百多年来被译成各种文字出版发行。一个没有读过达尔文自传的人是无法了解达尔文的。 1 关于达尔文的自传 达尔文从1876年5月28日开始写作《我的思想和性格的回忆录（Recollections of the development of my mind and character）》，每天午后写一个小时左右，8月3日写完。后来在1878年和1881年，作了一些补充和修改；最后又在1881年5月1日，续写《补记》。达尔文于1882年4月19日去世。在他逝世5年后的1887年，他的儿子法朗士（Francis Darwin）删除其中一些被认为是家庭内琐事和有损达尔文死后名声的章节，以《自传》为题，把它编印在《达尔文生平及其书信集（Life and Letters of Charles Darwin）》三卷本中； 1929年，以《达尔文自传》为书名出版独立的单册。删去部分达四分之一之多，主要包括达尔文对家庭成员、朋友的评价和他的宗教观念。1957年，苏联生物学家索波里根据达尔文的《回忆录》原稿，第一次把未删的抄本译成俄文，出版单行本册。1958年，达尔文的孙女诺拉?巴洛（Nora Balow），根据另一全抄本编辑出版了《达尔文自传（The Autobiography of Charles Darwin）》，并加添重要的附录。1974年，英国动物学家加文?德贝尔（Gavin De Beer）根据诺拉的版本和詹姆土?金斯利核对原稿全本后的校订意见而修正，编辑出版《达尔文和赫胥黎自传》。 2 关于达尔文自传的中译版本 1982年之前中国出版的版本有 （1）1917年，周太玄翻译，连载在《学生杂志》第四卷第一期、第三期和第七期。（2）1935年，张孟闻翻译，北平钟山书局山版；（3）1935年，周韵铎翻译，上海世界书局出版；（4）1939午，全巨荪翻译，上海商务印书馆出版。除《自传》删改本外，还有法朗士的附录两篇；（5）1947年，苏桥翻译，上海生活书店出版。以后又在另外几个出版社再版；（6）1957年，叶笃庄和孟光裕合译《达尔文生平及书信集》（第一卷第二章 自传），北京三联书店出版。以后又在其他出版社再版。这些版本都是根据法郎士的删节本翻译的。1982年，毕黎翻译了诺拉?巴洛编辑的《达尔文自传（未删本）》，增加了若干注释和附录，以《达尔文回忆录》为名，由商务印书馆出版。这是国内最完整的、最全面的达尔文自传版本，被多次重印。1998年曾向阳也根据法郎士的删节本翻译了《达尔文自传》，由江苏文艺出版社出版。 3 不同版本的译文－以序言为例 在文章的序言部分，达尔文以非常简短的语言，清楚地交待了自己写作的缘由、意义、方式和风格。作者因德国记者之邀请而写回忆录，但他认为把它写下来留给子孙后代阅读是很有意思的。他表明自己年岁已高，心态平和，因此以死者的角度出发就不会掩饰自己的缺点，也不会特别在意文章的风格体裁。 尽管不同的版本文字略有区别，但序言的英文原文是相同的：①A German Editor having written to me for an account of the development of my mind and character with some sketch of my autobiography, I have thought that the attempt would amuse me, and might possibly interest my children or their children. ②I know that it would have interested me greatly to have read even so short and dull a sketch of the mind of my grandfather, written by himself, and what he thought and did, and how he worked. ③I have attempted to write the following account of myself, as if I were a dead man in another world looking back at my own life. Nor have I found this difficult, for life is nearly over with me. I have taken no pains about my style of writing.（带圈数字为笔者为便于分析所加，下同） 以下译文1到译文5是5本不同的中译本中对序言的翻译文本。 译文1来自周韵铎翻译的《达尔文自传》：①一位德国记者来信，约我写一篇专述我的精神与性格之发展而含有自传性质的素描文字，这一种笔墨的尝试，我颇以为不仅足以使我自己欢娱，或许还足以引起我的孩子们及他们的孩子们的兴趣，也说不定。②尝记得我的祖父在世的时候，他也会自撰过一篇素描文字，叙述自己的精神、思想、事业以及工作方法，虽略嫌短小而欠生动，然而确会引起过我很大的兴趣的。③如今，我试作如下的自传，这正与在阴间中的死人回顾其生平的情形相仿佛。这事我并不感到困难，因为我的生涯是快要终结的了。至于用笔方面，我也不费劲道的了。 译文2来自全巨荪翻译的《达尔文传》：①一个德国的编辑人，写信向我要关于我的思想和性格发展的经过，以及我生平杂记之类。我想这件事情倒很有趣味，或许连我的后代子孙也会感到有意思。②我记得我是怎样的快乐，当我读了我父亲自己写的一些随笔，虽然那些文章写得很短而晦涩，但是明白地告诉了人家关于他所想的做的和如何做的。③我满想把我自己的写出来，好像一个已经死了的人回头想到自己的生平。这件事于我并不难办到，因为生命似乎不久就要完结。我现在所写的文字，是不拘什么格式的。 译文3来自苏桥翻译的《达尔文自传》：①一位德国的编辑曾经要我写一篇关于我的思想和性格的发展经过，附带讲一点我的生平。我觉得这种工作很足以自娱，而且还可以让我的子女以及他们的子女感到兴趣的。②我知道我一定会感到极大的兴趣，如果我能够读到我的祖父的自述，叙述他的思想、他的所思所为以及他如何工作。③我现在准备把我的生平写在下面，有如我是一个已死的人回顾自己的过去。我并不觉得这是一桩困难的工作，因为我已是垂死的老人。对于我的行文的风格，我也不加注意。 译文4来自叶笃庄、孟光裕翻译的《达尔文生平及书信集》（第一卷）： ①有一个德国编辑来信要我写一篇文章，叙述我的思想和性格的发展，并略微谈一谈我的生平，我曾想到这个工作对于我将是一种消遣，并且可能使我的孩子们和他们的孩子们感到兴趣。②如果我能读到我祖父自己写出的关于他的回忆、他所想的和所做的事情和他的工作方法的略记，哪怕是很短的和很不清楚的，我知道也会使我大感兴趣。③我试着把我的自述写在下面，就像我是在另一世界中的一个死去的人来回顾自己的生平。我觉得这也不难，因为我的生命几乎就要结束了。对于文章的体裁，我没有费力讲求。 译文5来自毕黎翻译的《达尔文回忆录》：①一位德国编辑来信，要我写述自己的思想和性格的发展以及生平简史；我认为，这种写作尝试，对我是一种消遣，也可能使自己的后代子孙们感到兴趣。②我想，要是自己的祖父亲手写过他的思想概要，讲述他想到些什么，做了些什么，以及他的工作怎样做法，即使写得简短而且晦涩，那么我也会津津有味地去阅读它的。③我尝试用下面的方式来写一篇自传，就是：好象使我自身处在另一个世界，却回头来把自己当做是一个亡故的人来写他的传记。我觉得，这也不算是一件难事，因为我现在已经是风烛残年，距死不远。我完全不必顾虑到它的文体优劣了。 4 对译文的比较分析 同样的一段文章，不同的版本对这段文字的翻译也不尽相同，有的甚至出入很大。下面将对此进行简单的分析。 第①句，译文1把英文中的editor译为了记者，其余译文都译为 编辑。editor英文释义为 person who prepares another persons writing for publication esp. in a newspaper or other periodical 、 person who directs writing of newspaper or news programmer,即尤指在报刊上为别人的文章出版做准备的人、指导报刊写作的主编或者新闻专栏的主笔，显然不是reporter(报纸新闻记者)或者journalist(期刊新闻记者)，尽管有的记者也承担编辑的任务。很遗憾的是，这个德国编辑到底是谁，具体做什么工作，没有历史纪录。译文1中也说不定几个字也属多余。译文2和译文5对my children or their children进行了意译，为自己的后代子孙；而译文1、3、4都进行了直译，为我的孩子们和他们的孩子们。意译既简洁又不失原意，是较好的译法。 第②句，原文是一个虚拟语句，这在译文3、4、5中得到了体现。译文1译得模棱两可。译文2则完全译错了，把它当成了一个过去时，而且把grandfather 错成了父亲。在达尔文的有关传记中，我们不曾发现他的父亲或者祖父写过自传性质的文章。还有dull一词，译词各不相同，如欠生动、晦涩、 很不清楚。译文3则漏译了even so short and dull。对照上文， dull应是不生动、枯燥无味，这和第一句感到有趣相吻合。因此， even so short and dull译为即使短且无趣为好。 第③句，也以一个虚拟的假设开始，表明了作者写作的视角、方法和态度。这段文字的几个译本似乎都不能令人满意，普遍的原因是过于拘泥于原文的直译。例如，as if I were a dead man in another world looking back at my own life的译文都显得啰嗦，不如译为有如逝者回首自己的一生来得简洁。另一个著名科学家爱因斯坦在应人之邀写作自述时，也有类似的表述：我已经 67岁了，坐在这里，为的是要写点类似自己的讣告那样的东西。 5 结语 对同一段文字，不同译者的翻译各有千秋，但也存在不同的缺陷。一篇精准的译文可能需要很多人的共同努力，去粗取精，才能臻于完善。后来的译本，如能吸取前面的版本的精华，也会达到相同的效果，但这会留下抄袭他人译文的嫌疑，这是后来的译文不一定会超越原来的译文的客观原因之一。 （该文同时贴在 www.casted.org.cn/blog ）
标签: 翻译
