[转帖]A week's worth of science news, Oct. 15

乏味 · 发表于 2006-10-18 16:59:00

It's harder to track down and costs more than the conventional variety, but organically grown wheat isn't any better for you nutritionally. On the other hand, it's likely no worse either.

This ambiguous message comes from the most rigorous scientific comparison yet between the nutritional content of a foodstuff grown under both carefully controlled organic and conventional farming methods. The results will be published Wednesday in the journal Agricultural Food Chemistry.

Scientists at Germany's Federal Research Centre for Nutrition and Food used wheat grown at a Swiss research institute where the plots have been monitored for 21 years, some farmed organically and some farmed conventionally with chemical fertilizers.

This tightly controlled research avoids the biggest pitfall of earlier studies, which usually compared organic versus conventional methods by analyzing foods from the marketplace. As lead author Christian Zorb points out, products on store shelves can have major differences in sites, cultivars, fertilization levels and harvest criteria, any of which could change the nutritional profile.

When the German biochemists compared their matched organic and non-organic wheats, there was no significant difference in 44 metabolic substances, including 11 amino acids, 13 sugars or sugar alcohols, 12 organic acids and eight other metabolites.

While the research didn't detect any significant difference in the quality of the wheat grains, the yield from the organic approach was about 30 per cent lower than from conventional fields. But it also used less fertilizer and no herbicides or pesticides. So there's probably an ecological payoff, but not a nutritional one.

Look away, children

"Look at me when I'm talking to you," is a common plaint from teachers and parents.

Yet children should actually be doing exactly the opposite when trying to concentrate on a problem, according to research just published in the British Journal of Developmental Psychology.

It's a technique called "gaze aversion" and comes naturally to adults who often stare off into space when faced with a conundrum. But children need to be taught gaze aversion, says Gwyneth Dorothy-Sneddon from the psychology department at the University of Stirling in Scotland.

Dorothy-Sneddon and colleagues did just that, training 10 five-year-olds to look away when asked a question. The trained group did much better on mental math questions than 10 others given no coaching.

Explaining the improved performance, the researchers say many people are so distracted by the flood of emotions evident in faces that they can't think clearly. In another experiment, adults broke out in a sweat when asked to stare at a human face while counting backwards from 100 in increments of seven.

Interviewed during the British Association's Festival of Science this summer, Dorothy-Sneddon said she applies her research findings at home.

"I do this with my own kids when they're doing their homework. If they're looking at me I know they're not concentrating," she said.

Strong-arming molecules

Canadian physicists have introduced the "invisible hand" of Adam Smith into the decidedly non-economics world of quantum processes.

The hand is actually a sophisticated laser technique that lets researchers manipulate matter at the molecular level in bursts of a trillionth of a second, and without leaving any signs of interference.

"This is not a gentle thing we're doing. It's more of a strong-arm tactic," Albert Stolow of the Steacie Institute for Molecular Sciences at the National Research Council of Canada told Micro.

Stolow led a research team that devoted five years to coming up with a practical application of coherent control, a concept developed two decades ago by physicists Paul Brumer of the University of Toronto and Moshe Shapiro, now at the University of British Columbia. The concept centres on using lasers to control molecular processes.

The researchers from the NRC and Queen's University demonstrated their approach by using an ultrashort pulse from a powerful infrared laser to do the same job as a traditional catalyst — trigger a specific chemical reaction without leaving any of itself behind.

In effect, says Stolow, the laser field can shape the energy landscape across which molecules pass, directing the outcome of the chemical reaction. He compares this to a skier swooshing down a slope.

Earlier unsuccessful approaches to coherent control tried to give the chemical skiers all the necessary instructions at the top of the slope. Others hammered them so hard with the laser that they flew apart. The NRC-Queen's approach instead shapes the electric landscape in the trillionths of seconds as the chemical reaction is unfolding.

The success published in the current issue of the journal Science is a "proof of concept" demonstration employing a very simple chemical reaction. Yet this same invisible-hand approach should apply to the entire field of quantum mechanical effects, thus making possible delicate control of switches no bigger than a molecule and opening up new possibilities in the burgeoning field of quantum information.

Click here

http://www.snowcrystals.com

The U.S. postal service turned to Kenneth Libbrecht, a physics professor at Caltech, when they wanted stunning photographs of snowflakes to adorn these new commemorative stamps for the coming holidays. And Libbrecht turned to Northern Ontario, where he photographed two of the four flakes (upper left and lower right).

Find out how to distinguish a stellar dendrite from a sectored plate on Libbrecht's comprehensive and well written website. He also explains how a point-and-shoot digital camera can produce decent flake pictures, although his own technique is far more exacting.

URL FROM:http://www.thestar.com/NASApp/cs/ContentServer?pagename=thestar/Layout/Article_Type1c=Articlecid=1160825229279call_pageid=970599119419

Tracy2006 · 发表于 2006-10-21 05:45:00

A week's worth of science news, Oct. 15

一周最有价值的科技新闻(10月15日)

It's harder to track down and costs more than the conventional variety, but organically grown wheat isn't any better for you nutritionally. On the other hand, it's likely no worse either.

从营养角度看,有机大麦虽然没什么好处,但是从另一方面讲,也没什么坏处

This ambiguous message comes from the most rigorous scientific comparison yet between the nutritional content of a foodstuff grown under both carefully controlled organic and conventional farming methods. The results will be published Wednesday in the journal Agricultural Food Chemistry.

这则隐晦的消息来自传统方法生产作物与有机方法控制作物在营养上的最严格的科学比较.结果将在农业与食品化工杂志上公布.

Scientists at Germany's Federal Research Centre for Nutrition and Food used wheat grown at a Swiss research institute where the plots have been monitored for 21 years, some farmed organically and some farmed conventionally with chemical fertilizers.

德国联邦研究中心的食品营养专家在瑞士研究所进行传统方式和有机肥料种植小麦的实验,计划已经进行了21年.

未完待续


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[转帖]A week's worth of science news, Oct. 15

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