2009年8月27日 星期四

【轉貼】冰層消覓食難北極熊軀體縮小







Environmental stresses could be causing physical changes in the bears
Polar bears are one of the most polluted mammals on the globe
The team used skulls from the Zoological Museum of Copenhagen
The maximum sea ice extent is declining by about 2.7% per decade

2009-08-27 中國時報 【潘勛/綜合廿五日外電報導】

丹麥科學家比對百餘年來的北極熊顱骨變化後推斷,因為環境惡化,現存北極熊的軀體相較於一百多年前的熊祖先,已經縮小。

 研究團隊比對「哥本哈根動物博物館」收藏的近三百具北極熊顱骨,發現過去一百廿年間,顱骨尺寸縮減的幅度在二%至九%之間。

 研究報告主撰人「奧胡斯大學」生物學教授裴托迪表示,丹麥團隊研究那批顱骨、顱骨形狀及尺寸變化,可以判斷北極熊軀體大小改變。研究成果發表於《動物學期刊》(Jounal of Zoology)。

 裴托迪表示,北極熊軀體縮小,按推斷原因在環境惡化,造成「生理壓力」。首先,全球暖化,北極海冰層因消融而縮小,北極熊耗費在覓食的力氣增加,因此沒有額外精力讓身軀長大。

 再來,人類製造的化學汙染物存留在北極熊體內,也造成北極熊生育率減少。由於生育率降低,導致交配對象減少,北極熊近親繁殖現象增加,連帶改變了北極熊顱骨的形狀。

 裴托迪表示,北極熊受化學汙染影響特別重,原因是牠們位居食物鏈頂端;食物鏈較低層生物,如魚及海豹等凡沾染汙染物者,都匯聚到北極熊脂肪內。


'Stress' is shrinking polar bears

By Victoria Gill
Science reporter, BBC News

Polar bears have shrunk over the last century, according to research.

Scientists compared bear skulls from the early 20th Century with those from the latter half of the century.

Their study, in the Journal of Zoology, describes changes in size and shape that could be linked an increase in pollution and the reduction in sea ice.

Physical "stress" caused by pollutants in the bears' bodies, and the increased effort needed to find food, could limit the animals' growth, the team said.

The researchers used the skulls as indicators of body size. The skulls from the later period were between two and 9% smaller.

"Because the ice is melting, the bears have to use much more energy to hunt their prey," explained Cino Pertoldi, professor of biology from Aarhus University and the Polish Academy of Science, and lead scientist in this study.

"Imagine you have two twins - one is well fed during its growth and one is starving. (The starving) one will be much smaller, because it will not have enough energy to allocate to growth."

The team, which included colleagues from Aarhus University's Department of Arctic Environment, also found shape differences between the skulls from the different periods.

This development was slightly more mysterious, said Dr Pertoldi.

He explained that it was not possible to determine the cause, but that the changes could be linked to the environment - more specifically to pollutants that have built up in the Arctic, and in the polar bears' bodies.

The aim of the study was to compare two groups of animals that lived during periods when sea ice extent and pollution levels were very different.

The pollutants that the scientists focused on were compounds containing carbon and halogens - fluorine, chlorine, bromine or iodine.

Some of these compounds have already been phased out, but many still have important uses in industry. These include solvents, pesticides, refrigerants, adhesives and coatings.

Genetic brink

The changes, the team says, could also be related to a reduction in the genetic diversity of the species.

Hunting over the last century, said Dr Pertoldi, could have depleted the gene pool, leaving polar bears to suffer the effects of inbreeding.

"We also know from previous studies that some chlorinated chemical pollutants have affected the fertility of the females," he continued.

Rune Dietz from Aarhus University was another member of the research team.

He explained that he and his colleagues had already determined a link between man-made "persistent organic pollutants" and reduced bone mineral density in polar bears - which could leave the animals vulnerable to injury and to the bone disease osteoporosis.

Skull collection

The collection of almost 300 polar bear skulls was provided by the Zoological Museum of Copenhagen in Denmark.

Christian Sonne, a veterinary scientist from Aarhus University who worked with the team, said that this provided a unique and "fantastic sample", providing a window into the bears' development over a whole century.

During that time, he said, concentrations of many man-made pollutants in the Arctic have significantly increased.

He said: "Polar bears are one of the most polluted mammals on the globe."

2009年8月18日 星期二

【轉載】DNA電腦晶片 更小更強更省電

中國時報 2009-08-18 【潘勛/綜合十七日外電報導】

 美國電腦研究專家表示,他們已找到利用去氧核醣核酸(DNA)分子技術製造下一代微晶片的方法,而以DNA分子取代傳統的矽元素來造出微電路,可讓晶片變得更小,功能更強,也更省電。但專家也表示,這種晶片要進入商業量產,至少還要好幾年。

 美國IBM公司與加州理工學院專家羅斯蒙德合作;羅斯蒙德幾年前便判定,DNA分子可以「自我組合」成微小形狀,如三角形、正方形及星形。借用DNA的天然能力,可以吸收大量的複雜資訊,轉而運用在其他類型的活動。

 IBM公司研究許多方法,讓DNA在晶片表面自組成圖案,然後充當某種「支架」,再用數百萬奈米碳管及奈米粒子沉積上去。IBM科學家表示,如此奈米碳管及奈米粒子形成的新網絡,可以充當未來電腦晶片的線路及電晶體。

 具體而言,科學家先以傳統晶片技術蝕刻所需的電路圖形,再將DNA溶液倒在矽晶表面,此時DNA會依蝕刻的電路圖形自我組合成微小的三角形、正方形,這種能力,科學家稱之為「DNA的摺紙技術」(DNA origami)。如能將這些微小的DNA摺紙技術放置在晶圓表面,那麼科學家便能利用DNA的特性,製作出奈米電路板。

 這篇論文發表在最新《自然奈米科技》期刊。過去數十年,矽晶技術不斷微縮,將更小的線路蝕刻在晶片表面,以增進速度表現,同時減少電力消耗。目前最先進的電腦晶片是用四十五奈米製程製造,但再過幾年,要降到廿二奈米以下便瀕臨矽晶材料的物理極限,將變得更為困難、昂貴。


延伸閱讀:
Folding DNA to create nanoscale shapes and patterns
Design of DNA origami
Six-Helix Bundles Designed from DNA

2009年8月13日 星期四

Flâneur




"Flâneur"在法文原指流浪漢、街道晃蕩之意。波特萊爾Charles Baudelaire開發其意為“在街頭行走以觀察體驗都市生活”的意思。其背景是在19世紀工業革命下,新式蒸氣發動機、紡織機、火車等各式工具以及金融革命推波助瀾下,從而襲捲而來創造的新型大都會、新型生活型態所引發的思考。這也引發其後許多關於都市的研究與想法:日常生活、由下而上等等。

2009年8月4日 星期二

Golan Levin's artwork

interstitial fragment processor



scrapple installation



TED lecture



在TED上看到Golan Levin的作品,覺得相當有趣。他的互動作品具備了收集即時資訊、處理、表現,同時也帶著幽默。

2009年8月3日 星期一

robot cooking noodles



機械人煮拉麵!雖然是噱頭,複製汽車工業的機械人。但是刺激力道還是呱呱叫!