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2014-03-17    来源:网络    【      美国外教 在线口语培训

The human brain is wired to react fearfully to snakes, including in people without a conscious fear of snakes, says a study in this month's issue of Biological Psychology.
《华尔街日报》―发表于《生物心理学》(Biological Psychology)二月刊的研究论文称,人类大脑对蛇天生的反应就是畏惧,没意识到自己怕蛇的人也包括在内。

The study suggests the brain evolved to pay greater attention to the presence of snakes than other creatures, because snakes were among the earliest human predators and posed a daily threat.

This heightened awareness of snakes is embedded in the brain's circuitry, even though snakes are no longer a danger to most people, researchers said. Fear of spiders, while also common, has no evolutionary associations, as spiders weren't predatory, they said.

The study involved 24 non-phobic Norwegian women, 18 to 31 years old. The women viewed two sets of color photos while an EEG measured activity in their brain. In the first set, 600 pictures each of snakes, spiders and small birds were randomly displayed on a computer at a rate of three per second. This test assessed which creature attracted the subjects' instant -- but unconscious -- attention. They then viewed 30 pictures of each species at a slower speed to assess the brain's continuous neural response.

Before the tests, the subjects rated their fear on a scale from 0 (none) to 45 (very high). The average scores for snakes, spiders and birds were 16, 12 and 4, respectively. Compared with the spider and bird pictures, the speedy display of snake images evoked a significantly stronger brain response that was most pronounced in the brain's occipital or visual processing region, researchers said.

The response to the spider pictures was closely associated with the subjects' self-reported fear. Spider fear is learned and stems from disgust rather than fear of physical harm, the study suggests.

In the second test, the brain responses to spiders and snakes weren't significantly different, but were stronger than for birds.

Caveat: The study was small and only involved women.

Breast-milk benefit: A specialized antibody in breast milk may play an important role in a newborn's susceptibility to intestinal infections and inflammatory bowel diseases as they mature, suggests a study published online in the Proceedings of the National Academy of Sciences.
母乳的好处:发表于《美国国家科学院学报》(Proceedings of the National Academy of Sciences)网络版的一项研究显示,母乳中的一种特殊抗体或许对新生儿逐渐长大时是否易于患上肠道感染和炎症性肠病有很大的影响。

Breast milk contains an antibody called secretory immunoglobin A (SIgA), which protects against infection and helps infants develop a healthy mix of gastrointestinal bacteria. When breast-feeding stops, other mucus-secreting organs, such as the nose, throat and eyes, start to produce SIgA, but it wasn't known if the initial exposure to SIgA through breast milk had long-term benefits, researchers said.

A purified form of SIgA might be a potential treatment for intestinal infections and inflammation, particularly in formula-fed infants or older children and adults who don't produce enough of the antibody, they said.

Experiments at the University of Washington in Seattle were conducted on the offspring of mice that produced breast milk with SIgA and mice bred to produce milk without the antibody. Analysis of fecal samples showed SIgA was present only in offspring that received the antibody and fell to low levels after weaning. Within a week, the weaned mice began to produce SIgA through other tissues, while SIgA wasn't detected at any time in mice that didn't receive the antibody. Mice lacking SIgA had significantly different gut bacteria than mice with the antibody, including Ochrobactrum anthropi, a bacterium linked to hospital-acquired infections.
西雅图华盛顿大学 (University of Washington in Seattle)对老鼠的后代展开了实验,其中一些老鼠分泌含SIgA的乳汁,另一些因喂食方法分泌的是不含该抗体的乳汁。对排泄物采样的分析表明,SIgA只在喂有含该抗体的乳汁的幼鼠中出现,但抗体水平在断奶后降至低位。在一周之内,断奶幼鼠的其他器官组织便开始生成SIgA,而未被喂食含SIgA乳汁的幼鼠从未被检测出该抗体。缺乏SIgA的老鼠与含该抗体的老鼠的肠道细菌大为不同,其中包括与医院获得性感染有关的人苍白杆菌。

The addition of a chemical used to induce colitis in laboratory mice caused significantly greater tissue damage in the mice that didn't receive SIgA. Intestinal gene patterns also differed significantly between the two groups.

Caveat: It's possible that maternal differences in gut microbes at the time of delivery contributed to the genetic changes in offspring independently of SIgA in breast milk, researchers said. The research was conducted on rodents and hasn't been tested in human studies.

Reducing salt consumption by half a teaspoon a day significantly improved blood-vessel function in overweight and obese individuals with normal blood pressure, potentially lowering their risk of cardiovascular disease, according to a report in the March issue of Atherosclerosis.
《动脉硬化》(Atherosclerosis) 杂志三月刊的一项报告指出,将每日的盐摄入量减少半匙可改善超重人群及血压正常的肥胖人士的血管功能,有可能降低他们患上心血管疾病的风险。

The magnitude of the blood-vessel changes recorded in the study could shift a person from a high-risk category to a low-risk one for heart attack and stroke, which are associated with a high-salt diet, researchers said.

The Centers for Disease Control and Prevention recommends consuming no more 6 grams (2,300 milligrams of sodium), or one teaspoon of salt a day. For African-Americans, diabetics and people older than 51 or with high blood pressure, the CDC recommends consumption be limited to two-thirds of a teaspoon (about 4 grams of salt or 1,500 milligrams of sodium). Most Americans consume an average of 9 grams of salt (3,450 milligrams of sodium) a day, according to the CDC.
美国疾病控制与预防中心(Centers for Disease Control and Prevention,简称“CDC”)建议每日的食盐量不要超过六克(2,300毫克钠),也就是一天一茶匙盐。对于非裔美国人、糖尿病患者以及51岁以上的人群或高血压患者,CDC的建议把摄入量控制在三分之二茶匙(约为四克盐或1,500毫克钠)。根据该中心的数据,美国人每日的盐摄入量平均为九克(3,450毫克钠)。

Researchers at the University of South Australia recruited 25 men and women ages 40 to 70 for the 12-week study. The subjects followed a diet containing 9 grams of salt a day for six weeks and a reduced salt diet of 6 grams a day for six weeks. Flow-mediated dilatation, an ultrasound technique used to assess blood-vessel elasticity, was measured at the start of the study and after two, six and 12 weeks.
南澳大学(University of South Australia)的研究人员征集了25名年龄在40岁至70岁的男女受试者参加为期12周的实验。受试者前六周的饮食遵照的是每天九克的盐摄入量,在接下来的六周中将摄入量减至每天六克。与此同时,研究人员分别在研究一开始、两周后、六周后以及12周后检测采用血流介导的血管舒张功能,这是一种用于评估血管扩张度的超声波技术。

Blood-vessel function significantly increased on the reduced salt diet after two days compared with the higher salt diet, and by 45% over six weeks. Levels of endothelin-1, proteins that constrict blood vessels and raise blood pressure, decreased by 14%.

The subjects' blood pressure and weight remained the same, indicating the reduced-salt diet had an independent effect on vascular health, researchers said.

Caveat: The study was small and lacked a control group of normal-weight people.

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