外文翻譯--有爭(zhēng)議的研究科學(xué)的好與壞

1、<p><b>　　譯文：</b></p><p>　　有爭(zhēng)議的研究：科學(xué)的好與壞</p><p>　　工作于因流感引起的變異，但這并非唯一一個(gè)風(fēng)險(xiǎn)可能會(huì)超過(guò)受益的項(xiàng)目。</p><p>　　Geoff Brumfiel</p><p>　　這聽(tīng)起來(lái)像一個(gè)很偉大的想法：實(shí)驗(yàn)變異產(chǎn)生一種罕見(jiàn)且致命的病毒以便于科學(xué)

2、家在認(rèn)識(shí)新興的菌株方面做更好的工作。但這聽(tīng)起來(lái)也像一個(gè)可怕的想法——這項(xiàng)研究可以創(chuàng)造一種易于傳播和生產(chǎn)的病毒，它將有益于有益使用生物武器的恐怖分子。</p><p>　　去年的新聞?wù)f道兩個(gè)研究小組已經(jīng)完成這項(xiàng)工作，但H5N1禽流感病毒就足以在全球各地造成恐懼，因此迅速暫停了工作。的一位美國(guó)生物安全小組已經(jīng)撤銷將調(diào)查結(jié)果公布在Nature和Science上的限制，認(rèn)為工作有明確的潛在好處，社區(qū)的數(shù)據(jù)循環(huán)研究顯示變異

3、后的病毒似乎比原來(lái)少致死。但這段插曲突出顯示了在有意義的研究和有威脅的研究之間的分界線是多么的薄。</p><p>　　在許多科學(xué)領(lǐng)域充滿這樣的調(diào)查。有些人可能會(huì)破壞全球安全，而其他人可能會(huì)為家庭創(chuàng)造困境。這四個(gè)自然的例子顯示，這里幾乎沒(méi)有明確列出一個(gè)來(lái)，但他們真的感覺(jué)到這個(gè)難題出現(xiàn)的是多么的頻繁—— 科學(xué)家們必須不斷地問(wèn)自己，是否利大于弊。</p><p><b>　　核燃料或

4、核武器？</b></p><p>　　一種可以快速有效的區(qū)分核電廠和核醫(yī)學(xué)的放射性同位素的技術(shù)是很多物理學(xué)家夢(mèng)寐以求的。但同位素分離也是制造核武器的關(guān)鍵，因此，這種技術(shù)可以更容易執(zhí)行和隱瞞對(duì)這類武器的非法工作。</p><p>　　自然存在的鈾礦石，主要是鈾-238，不能維持爆炸需要的鏈?zhǔn)椒磻?yīng)，只有裂變成0.7%濃度鈾-235才行。反應(yīng)堆使用的原料多集中于濃度3-5%。而制造原

5、子彈，它必須被濃縮到90％以上，從一個(gè)到另外一個(gè)的分類一直是核武器擴(kuò)散的主要障礙之一。今天一個(gè)國(guó)家的最先進(jìn)的技術(shù)，涉及到數(shù)千臺(tái)離心機(jī)，因此需要大量的空間、電力，精密加工的零件和時(shí)間。</p><p>　　激光可以更加高效。鈾原子核的微小質(zhì)量差異改變其電子殼層的能量水平。微調(diào)的激光與其他技術(shù)一起可以激發(fā)所需的同位素的水平，可以從剩余的里面區(qū)分出鈾-235。這工作可以做的很快速秘密。在2004年，韓國(guó)的科學(xué)家大約在幾

6、周之內(nèi)發(fā)現(xiàn)用激光可以讓少量的鈾-235來(lái)靠近造武器的純度。工作多年未被發(fā)現(xiàn)，最終向國(guó)際檢查人員披露。</p><p>　　現(xiàn)在，廉價(jià)和可調(diào)諧激光技術(shù)的問(wèn)世，在世界各地激光分離對(duì)物理學(xué)家而言是相對(duì)容易的，一個(gè)很好的例子是在得克薩斯大學(xué)奧斯汀分校的Mark Raizen，一個(gè)研究區(qū)分重要醫(yī)療同位素如鈣-48的人，在骨骼疾病的診斷上有重要醫(yī)療作用，還有鎳-64，一種治療癌癥的可靠藥劑，世界上正面臨緊缺這種醫(yī)療同位素，R

7、aizen說(shuō)：人們的生活將取決于尋找新的來(lái)源。 ”</p><p>　　Raizen的方法很簡(jiǎn)單：微調(diào)激光器用電將所需的同位素推入更高的能量狀態(tài)，暫時(shí)改變?cè)拥拇啪?。從這一點(diǎn)來(lái)說(shuō)，所有要做的關(guān)鍵部分只是需要分離一個(gè)同位素。</p><p>　　Raizen說(shuō)，他意識(shí)到，用激光和同位素工作帶來(lái)了核擴(kuò)散的危險(xiǎn)。但他爭(zhēng)論道：這和他的工作不同，他將用他的技術(shù)很好的工作于如鈾的重元素。</p&

8、gt;<p>　　其他人認(rèn)為激光鈾濃縮技術(shù)應(yīng)當(dāng)謹(jǐn)慎小心，“我認(rèn)為風(fēng)險(xiǎn)高，” Francis Slakey說(shuō)道，華盛頓喬治敦大學(xué)公共科學(xué)項(xiàng)目的主任。Slakey,一個(gè)公開(kāi)反對(duì)商業(yè)化激光分離核燃料同位素的人，喜歡見(jiàn)到一個(gè)在社會(huì)更加開(kāi)放的辯論—尤其那些在原子和分子光學(xué)領(lǐng)域與raizen研究方向相似的物理學(xué)家，“我認(rèn)為這有暫停和反應(yīng)的價(jià)值，”slakey說(shuō)道。</p><p>　　在良好的社會(huì)物理學(xué)的興奮驅(qū)

9、動(dòng)下，raizen正在向前推進(jìn)，至于風(fēng)險(xiǎn)，“你不能停止科學(xué)思想”，他說(shuō)道，如果他不這么做，別人也會(huì)做的。他希望他在一兩個(gè)月內(nèi)的第一個(gè)成果是在輕原子上，如鋰。</p><p><b>　　腦掃描或獨(dú)裁者？</b></p><p>　　一臺(tái)機(jī)器能夠準(zhǔn)確地讀取一個(gè)人的想法可能有非凡的好處—讓官方安全人員在恐怖分子行動(dòng)之前了解他們的行動(dòng)，比如，為一些腦部受損的不能動(dòng)或交流的病

10、人提供新的說(shuō)話方式。但此類設(shè)備可能也是科幻小說(shuō)中令人產(chǎn)生噩夢(mèng)的工具，它提高了獨(dú)裁者的鬼性和鎮(zhèn)壓思想自由的警察的警惕性。</p><p>　　這可能是為什么做這種“讀心”研究的更喜歡叫他腦掃描或腦解碼?！罢麄€(gè)心概念的到來(lái)使很多觀念都過(guò)時(shí)了，” Adrian Owen說(shuō)道，一個(gè)在倫敦的加拿大西安大略大學(xué)的神經(jīng)學(xué)家。</p><p>　　不過(guò)，這些研究人員在人類思想方面已經(jīng)取得了非凡的成績(jī)。最主

11、要的是磁共振的成像功能，這使得研究人員能夠監(jiān)督血液流過(guò)大腦的過(guò)程?，F(xiàn)在血流量被認(rèn)為是合理的神經(jīng)活動(dòng)，所以磁共振成像提供了腦病的動(dòng)態(tài)圖片。</p><p>　　例如，owen，工作于研究那些明顯因?yàn)橥鈧麄Τ蔀橹参锶说牟∪?。通過(guò)問(wèn)特殊的問(wèn)題來(lái)刺激腦部不同部位的活動(dòng)，他已經(jīng)可以確認(rèn)大概16%的此類病人可以做出回應(yīng)了，這表明他們已經(jīng)至少有了一些意識(shí)能力。</p><p>　　Jack Galla

12、nt,一名加利福尼亞大學(xué)伯克利分校的神經(jīng)學(xué)家，已經(jīng)開(kāi)發(fā)了一種能夠跟蹤在視覺(jué)皮層的激活模式的方法就像人們看電影一樣。改變這些計(jì)算機(jī)代碼可以創(chuàng)造人們?nèi)魏蜗肟吹奶摶玫碾娪?。Ganllant認(rèn)為這項(xiàng)工作能夠產(chǎn)生更多與那些癱瘓但蘇醒的或靠腦部機(jī)器聯(lián)系他們想法的病人的交流的先進(jìn)方法。</p><p>　　更進(jìn)一步分析，John-Dylan Haynes，一名意圖明確的柏林醫(yī)療大學(xué)的神經(jīng)學(xué)專家。Haynes掃描了腦子來(lái)看是否能

13、找到對(duì)應(yīng)于一個(gè)人的決定的行事模式。它適用于簡(jiǎn)單的情況：例如，他可以看到一個(gè)按鈕在按下去前幾秒時(shí)是否決定按下這個(gè)按鈕。</p><p>　　無(wú)論這項(xiàng)工作是否可以擴(kuò)展到實(shí)際的應(yīng)用程序，如測(cè)謊或反恐則是另一回事。Gallant說(shuō)道，首先，每一個(gè)人的大腦是不同的；它遠(yuǎn)不像科學(xué)家聲稱的將能夠研究出對(duì)于每個(gè)人都通用的大腦想法的公式。Haynes,又說(shuō)道，核磁共振成像機(jī)不能簡(jiǎn)單的部署在機(jī)場(chǎng)。即使他們部署了，一個(gè)簡(jiǎn)單的晃動(dòng)就會(huì)甩

14、掉他們。你不可能造一個(gè)能說(shuō)出“這個(gè)人正準(zhǔn)備炸毀一架飛機(jī)”的偵察器的。</p><p>　　即使如此，這種裝置的前景依然被人引起懷疑。Gallant說(shuō)道：“因?yàn)槟承┤巳绻軌蚴褂靡慌_(tái)機(jī)器獲得你最秘密的內(nèi)心想法的做法是不能令人接受的。”</p><p>　　然而已經(jīng)有企業(yè)家涉足這一領(lǐng)域。兩家美國(guó)公司已經(jīng)派出fRMI測(cè)謊服務(wù)，世上的廣告也已經(jīng)包含這種神經(jīng)營(yíng)銷學(xué)的理念——研究使用磁共振成像功能和其

15、他技術(shù)來(lái)衡量人的潛意識(shí)的情緒反應(yīng)的促進(jìn)因素。到目前為止，如此的努力使關(guān)注者增加似乎被認(rèn)為是在炒作。大多數(shù)法院已經(jīng)聽(tīng)從關(guān)于科學(xué)家對(duì)fMRI測(cè)謊的懷疑，并且不批準(zhǔn)作為證據(jù)，Steven Laken說(shuō)，斯公司的董事長(zhǎng)，在馬賽諸塞州廷斯波羅的的fMRI的測(cè)謊公司首席執(zhí)行官。Haynes說(shuō)道：神經(jīng)營(yíng)銷學(xué)是更加值得懷疑的。但是Gallant認(rèn)為這種應(yīng)用的技術(shù)將會(huì)隨之而來(lái)?！八鼤?huì)比你想像的走的更遠(yuǎn)”他說(shuō)道。</p><p>　

16、　氣候救世主或氣候?yàn)?zāi)難？</p><p>　　支持者說(shuō)，人類最大的希望是通過(guò)全球工程來(lái)逃離全球氣候變暖：在一個(gè)與地球相同比例的行星上操縱它的氣候環(huán)境。這可能涉及到太陽(yáng)的輻射管理——噴射微小的粒子到很高的平流層，例如，那些他們可以通過(guò)反射一些進(jìn)來(lái)的陽(yáng)光來(lái)進(jìn)行冷卻的地方?；蛘咚赡芙槿攵趸嫉某烦赡芡ㄟ^(guò)播種大量的鐵來(lái)創(chuàng)造藻花然后吸收空氣中的二氧化碳，最后當(dāng)他們死亡時(shí)帶到海底。</p><p&

17、gt;　　反對(duì)者說(shuō)，地球工程是極度魯莽的——并且可能進(jìn)一步惡化氣候使氣候變遷更加的不穩(wěn)定。</p><p>　　目擊一場(chǎng)關(guān)于英國(guó)政府是否應(yīng)該在平流層注射粒子的氣候工程注資的爭(zhēng)論，這些人包括布里斯托，劍橋，愛(ài)丁堡和牛津大學(xué)的專家們，更包含了在劍橋的英國(guó)氣象局和馬歇爾航空局。Spice是設(shè)計(jì)與測(cè)試日光輻射工程的原理證據(jù)。想法是抽1公里長(zhǎng)的水管的水將它噴灑入空氣。海拔太低的話是不能改變氣候的，在那兒它已經(jīng)有了大量水蒸氣

18、，David Keith說(shuō)道，一位在加拿大卡爾加里大學(xué)的一位全球工程專家。“這不同于將一根管子掉在某人頭上那樣具有危險(xiǎn)”他說(shuō)道。</p><p>　　然而，當(dāng)環(huán)保主義者在去年得知這情況時(shí)便敲響了警鐘。完全是因?yàn)榈厍蚬こ炭赡軙?huì)引起潛在的意想不到的后果——如不慎移位降雨模式并引發(fā)干旱——這樣一種工作存在道德危機(jī)，ETC組織的執(zhí)行董事Pat Mooney爭(zhēng)論到，這個(gè)環(huán)保組織是總部設(shè)在加拿大渥太華的。與世界各地的氣候談判

19、陷入僵局，在這樣恰好的時(shí)間參加這樣的實(shí)驗(yàn)很可能使政客們認(rèn)為有辦法設(shè)法逃避自己的任務(wù)帽責(zé)任?！斑@將是一個(gè)簡(jiǎn)單的辦法為政府回避自己的義務(wù)，”Mooney說(shuō)道。</p><p>　　ETC和其他團(tuán)體在去年秋天集體請(qǐng)?jiān)赣?guó)政府停止SPICE，在今年巴西里約熱內(nèi)盧舉行的氣候談判中說(shuō)道它將會(huì)損害國(guó)家的信譽(yù)，“在那時(shí)它并沒(méi)有得到一點(diǎn)阻礙，”一位英國(guó)達(dá)勒姆大學(xué)地理學(xué)家Phil Macnaghten說(shuō)道，他是負(fù)責(zé)對(duì)SPICE在倫理

20、和社會(huì)方面監(jiān)督的人。在2011年9月份，在專家與公眾和感興趣的團(tuán)體交流時(shí)Macnaghten和其他人建議暫停實(shí)驗(yàn)——目前，它仍然被擱置著。</p><p>　　Mooney希望看到全球協(xié)商一致的規(guī)則，包括地球工程實(shí)驗(yàn)的禁止以及跨國(guó)后的后果,直到重要問(wèn)題被回答了。例如，地球工程會(huì)繼續(xù)嗎？他可能會(huì)產(chǎn)生什么意想不到的后果？但是，隨著全球氣溫繼續(xù)上升，Macnaghten堅(jiān)信，假如專家回答公眾的擔(dān)心，這項(xiàng)科學(xué)將被允許繼續(xù)

21、進(jìn)行下去，“當(dāng)你不知道你不知道的是什么的時(shí)候，它是很難知道如何進(jìn)步的，”他說(shuō)道。</p><p>　　出處：Geoff Brumfiel，“Controversial research: Good science bad science”，Nature,2012.4.27</p><p><b>　　原文：</b></p><p>　　Cont

22、roversial research: Good science bad science</p><p>　　Work on mutant flu caused a furore, but is far from the only subject in which risks might outweigh benefits.</p><p>　　Geoff Brumfiel</p&g

23、t;<p>　　It sounds like a great idea: experimentally mutate a rare but deadly virus so that scientists can do a better job of recognizing dangerous emerging strains. But it also sounds like a terrible idea — the st

24、udies could create a virus that is easier to transmit and produce findings that are useful to bioterrorists.</p><p>　　Last year's news that two research teams had done exactly that with the H5N1 bird flu

25、 virus was enough to spread fear around the globe and prompt a temporary moratorium on the work. A US biosecurity panel has since lifted its restrictions on publication of the teams' findings in Nature and Science, a

26、rguing that the work has clear potential benefits, that the modified virus seems to be less lethal than the original and that the data are already circulating in the community. But the episode has hi</p><p>

27、　　Such fraught lines of enquiry exist in many scientific fields. Some could undermine global security, whereas others could create painful ethical dilemmas for families. The four examples Nature profiles here are hardly

28、a definitive list, but they do give a sense of how frequently such conundrums arise — and show that scientists must constantly ask themselves whether the benefits outweigh the risks.</p><p>　　Nuclear fuel or

29、 nuclear weapons?</p><p>　　A technology that could quickly and efficiently separate radioisotopes for nuclear power plants and nuclear medicine is one that many physicists might find irresistible. But isotop

30、e separation is also key to making nuclear weapons, so such a technology could make it easier both to perform and to conceal illicit work on such weapons.</p><p>　　Naturally occurring uranium ore is mostly u

31、ranium-238, which cannot sustain the kind of runaway chain reaction required to produce an explosion. Just 0.7% is fissile uranium-235. Enriching that quantity to 3–5% makes fuel for reactors. To make a bomb, it must be

32、enriched to more than 90%. Because the chemistry of the various isotopes is almost identical, sorting one from another has always been one of the major barriers to the proliferation of nuclear weapons. Today's state-

33、of-the-art technology</p><p>　　Lasers can be more efficient. Tiny differences in the mass of uranium nuclei alter the energy levels of their electron shells. Finely tuned lasers can excite just the levels as

34、sociated with the desired isotope and, together with other technology, can sort the uranium-235 from the rest. The work can be done quickly and secretly. In 2004, it emerged that scientists in South Korea had used lasers

35、 to enrich small quantities of uranium-235 to near weapons purity in a matter of weeks. The work went un</p><p>　　Now, with the advent of cheap and tuneable lasers, laser separation is within relatively easy

36、 reach of physicists the world over. A good example is Mark Raizen at the University of Texas at Austin, who is developing lasers to separate medically important isotopes such as calcium-48, used in the diagnosis of bone

37、 disorders; and nickel-64, a promising agent for cancer therapy. The world is facing a shortage of medical isotopes1, Raizen says. “People's lives will depend on finding new sources.”</p><p>　　Raizen'

38、;s technique is straightforward2: finely tuned lasers push electrons in the desired isotope into higher energy states, temporarily changing the atoms' magnetic moment. From that point, all that is needed to sort the

39、isotopes is a large, static magnet.</p><p>　　Raizen says he is aware that working with lasers and isotopes poses a proliferation risk. But he argues that it is unlikely that his technique will work well for

40、heavy elements such as uranium.</p><p>　　Others stress that laser-enrichment technology should be undertaken with caution. “I think the risks are high,” says Francis Slakey, co-director of the programme on s

41、cience in the public interest at Georgetown University in Washington DC. Slakey, who has openly opposed the commercialization of laser isotope separation for creating nuclear fuel3, would like to see a more open debate i

42、n the community — especially given that many physicists in the field of atomic and molecular optics could follow l</p><p>　　Raizen is pushing ahead, driven by the excitement of using physics for the good of

43、society. As for the risks, “you can't stop scientific ideas”, he says. If he didn't do it, somebody else would. He expects his first results, on light atoms such as lithium, in a matter of months.</p><

44、p>　　Brain scanning or Big Brother?</p><p>　　A machine able to accurately read a person's thoughts could be an extraordinary boon — allowing security officials to catch terrorists before they act, for

45、example, or providing a new voice to some brain-damaged patients who cannot move or communicate. But such a device could also be the stuff of science-fiction nightmares, raising the spectre of Big Brother and ever-vigila

46、nt thought police.</p><p>　　That may be why the scientists doing such 'mind-reading' research prefer to call it 'brain scanning' or 'brain decoding'. “The whole concept of 'mind&#

47、39; comes with a lot of baggage,” says Adrian Owen, a neuroscientist at the University of Western Ontario in London, Canada.</p><p>　　Nevertheless, these researchers have made extraordinary progress in under

48、standing the human mind. The key has been functional magnetic resonance imaging (fMRI), which allows researchers to monitor blood flow throughout the brain. Blood flow is believed to be a reasonable proxy for neural acti

49、vity, so fMRI gives a picture of the brain in action.</p><p>　　Owen, for example, has worked with patients who have been left in an apparently vegetative state by traumatic injuries. By asking specific quest

50、ions to stimulate activity in different parts of their brains, he has been able to establish that around 16% of such patients can respond4, suggesting that they have at least some level of awareness.</p><p>

51、　　Jack Gallant, a neuroscientist at the University of California, Berkeley, has developed algorithms that track patterns of activation in the visual cortex as people watch videos. Reversing those computer codes can creat

52、e shadowy movies of whatever people are looking at. Gallant thinks that this work could lead to even more advanced methods of communication with locked-in patients, who are paralysed but aware, or brain–machine interface

53、s that allow people to operate devices with their thoughts.</p><p>　　Going further still, John-Dylan Haynes, a neuroscientist at the Charité Medical University of Berlin, is looking for intent. Haynes s

54、cans the brain to see whether he can pick out patterns of activity that correspond to a person's decision to act. It works in simple cases5: he can see whether an individual decides to press a button up to seconds be

55、fore the button is pressed, for example.</p><p>　　Whether this work could be extended to real-world applications such as lie detection or counter-terrorism is another matter. For one thing, says Gallant, eac

56、h person's brain is different; it's far from clear that scientists will ever come up with a general-purpose 'mind-reading' algorithm applicable to everyone. For another, says Haynes, fMRI machines could n

57、ot easily be deployed in airports. Even if they were, a simple shake of the head would throw them off. “You can't build a detector that say</p><p>　　Nevertheless, even the prospect of such a device raise

58、s hackles. “The thought that someone could use a machine to gain access to your most secret inner thoughts is not pleasant,” says Gallant.</p><p>　　Yet entrepreneurs are already dabbling in this arena. Two U

59、S companies have fielded fMRI lie-detection services, and the world of advertising has embraced the concept of 'neuromarketing' — the use of fMRI and other techniques to measure people's subconscious emotiona

60、l responses to stimuli. So far, concerns raised by such efforts seem hyped. Most courts have listened to scientists' doubts about fMRI lie-detection, and are not admitting them as evidence, says Steven Laken, chief e

61、xecutive of Cepho</p><p>　　Climate saviour or climate disaster?</p><p>　　To hear proponents talk, humanity's best hope to escape the ravages of global warming may be geoengineering: manipula

62、ting Earth's environment on a planetary scale. This might involve solar-radiation management — spraying tiny particles high into the stratosphere, for example, where they could cool things down by reflecting some of

63、the incoming sunlight. Or it might involve the removal of carbon dioxide, perhaps by seeding the ocean with iron to create algal blooms that would take up carbon dioxi</p><p>　　To critics, geoengineering wou

64、ld be reckless in the extreme — and might further inflame the volatile politics of climate change.</p><p>　　Witness the controversy that has swirled around the UK-government-funded Stratospheric Particle Inj

65、ection for Climate Engineering (SPICE) project, which involves researchers from the universities of Bristol, Cambridge, Edinburgh and Oxford, as well as the UK Met Office and Marshall Aerospace in Cambridge. SPICE is a p

66、roof-of-principle project designed to test solar-radiation management. The idea is to pump water up a 1-kilometre-long hose and spray it into the air. The altitude is too low to alt</p><p>　　Nevertheless, en

67、vironmentalists sounded the alarm on SPICE as soon as they caught wind of it last year. Quite aside from geoengineering's potential for unintended consequences — such as accidentally shifting rainfall patterns and tr

68、iggering droughts — there is a moral hazard to such work, argues Pat Mooney, executive director of the ETC Group, an environmental organization based in Ottawa, Canada. With climate negotiations stalled around the world,

69、 the very presence of such an experiment may mak</p><p>　　ETC and other groups petitioned the British government to halt SPICE last autumn, saying it would hurt the country's credibility in this year'

70、;s climate talks in Rio de Janeiro, Brazil. “It did get a little bit bumpy at the time,” says Phil Macnaghten, a geographer at Durham University, UK, who is overseeing an ethical and societal assessment of SPICE. In Sept

71、ember 2011, Macnaghten and others recommended that the experiment pause while researchers engage with the public and interest groups — at p</p><p>　　Mooney wants to see internationally agreed rules that woul

72、d include prohibitions on geoengineering experiments with transnational consequences until major questions are answered. For example, will geoengineering even work? And what unintended consequences might it have? But as

73、global temperatures continue to rise, Macnaghten believes that, provided researchers answer public concerns, the science should be allowed to continue. “When you don't know what you don't know, then it's very

74、 hard to know </p><p>　　Baby blessing or Brave New World?</p><p>　　Within a pregnant mother's blood is her unborn child's full genetic sequence. Soon, say geneticists, the question will

75、no longer be how to get at it, but how to use it to understand the baby's future behaviour and health — and how to cope with the thorny ethical issues that will inevitably ensue.</p><p>　　The key to this

76、 new form of prenatal diagnosis lies in the fragments of DNA that float freely through every person's bloodstream. In pregnant women, around 15% of that DNA comes from the fetus, according to Dennis Lo, a pathologist

77、 at the Chinese University of Hong Kong, who is working to develop fetal genetic screening with Sequenom, a biotechnology company based in San Diego, California.</p><p>　　The trick is figuring out which DNA

78、belongs to the fetus and which belongs to the mother. Finding the father's genetic contribution is easiest. Researchers extract DNA from the expectant mother's blood and look for variations in common with the fat

79、her's genetic code to separate his half of the fetal DNA. The mother's half is tougher to identify because it is identical to the rest of the DNA in her blood. To find it, researchers count the number of times pa

80、rticular versions of genes are sequenced</p><p>　　Screens for specific diseases based on this method are already nearing the market, says Lo. Scientists can check for Down's syndrome, a disorder that ari

81、ses when an embryo receives three copies of chromosome 21, instead of the usual two. The test is more than 95% sensitive, making it comparable to more invasive tests such as amniocentesis6. Because it carries no risk, Lo

82、 believes that it will soon become nearly universal.</p><p>　　It may sound positive that many more parents will be forewarned of Down's syndrome and other genetic diseases such as cystic fibrosis, but it

83、 raises some thorny societal questions, says Henry Greely, a bioethicist at Stanford University in California. With universal screening, many more pregnancies might be terminated — and women who choose to carry a child w

84、ith, say, Down's syndrome to term could face social and legal stigmas, he warns. “There are countries that are very concerned about mental </p><p>　　Going beyond targeted diseases, full sequencing of the

85、 fetal genome is technically possible and will soon be affordable, says Stephen Quake, a researcher at Stanford University who works with Verinata Health, a fetal-screening company in Redwood City, California. And that,

86、says Greely, will raise even more contentious issues. “People who come from a family with Alzheimer's might choose to terminate a pregnancy at high risk of Alzheimer's even though that Alzheimer's might occur

87、 65 years into the</p><p>　　At present, there are no guidelines on how to counsel prospective parents about the avalanche of genetic information they may be about to receive. Lo says that he would be wary of

88、 telling parents before birth about a disease that could be cured within a child's lifetime. “Who knows where medical science will be in 60 years?”</p><p>　　But that is no reason to stop the research, sa

89、ys Quake, who has a cousin with Down's syndrome. He says he has thought long and hard about the issues raised by early testing, but in the end feels that the benefits greatly outweigh the risks. “The earlier parents