Comparer des articles de revues scientifiques en anglais 33178

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EICH Christie

Licence 3 Bio-Eco

Homework in English

Subject A: Compare two articles of English-speaking magazines on the following subjects:

- Naturals disasters.

- Stem cells / Cancer / Cloning.

1. Naturals disasters

Indian cyclones soar

Article de Alicia Newton, publié le 4 Septembre 2008 dans Nature Report Climate Change

The frequency and intensity of summer tropical cyclones forming in the north Indian Ocean could increase in the coming century, according to scientists. Tropical storms such as the recent Cyclone Nargis, which made landfall in May and caused thousands of fatalities, are common in spring and late fall. But the onset of the summer monsoon system has usually prevented summertime tropical storm activity.

V. Brahmananda Rao at the Center for Weather Forecast and Climate Studies, São Paulo, Brazil, and colleagues assessed the causes of increased summer tropical-storm activity over the north Indian Ocean, which saw its first-ever category 5 hurricane in June 2007. They found a strong statistical link between increasing numbers of storms and the weakening of the Tropical Easterly Jet associated with the summer monsoon. The decline of the jet resulted in decreased wind shear in the atmosphere above the ocean, creating a prime breeding ground for violent storms, say the scientists.

Greater summer storm activity poses a hazard to millions of people living in low-lying deltas and coastal plains surrounding the Indian Ocean, especially those already inundated with monsoonal rains and floods.

Cyclonic swirling

Article de Samia Mantoura , publié le 27 Juin 2007 dans Nature Report Climate Change

Ocean mixing plays a crucial role in global climate because it is linked to the ocean's capacity to store and transport heat from the tropics to cooler regions. Tropical cyclones are thought to be important drivers of ocean mixing and heat transport, but until now their relative importance has been uncertain.

Ryan Shriver and Matthew Huber of Purdue University in Indiana now present substantive evidence that tropical cyclones have a significant role in mixing the ocean's uppermost layers. Using more data and longer sampling periods than previous studies, the researchers compared ocean temperatures before and after the passing of tropical cyclones to estimate the effect of these events on vertical mixing. Shriver and Purdue say that up to 15% of peak ocean heat transport can be linked to vertical mixing driven by tropical cyclones. Their estimate that cyclones account for 0.26 petawatts per year of ocean heat transport is significantly smaller than earlier calculations.

More surprisingly, the results show that cyclone-induced heat transport increases substantially with higher sea surface temperatures, suggesting that climate change could alter ocean circulation and heat transport. Climate models could be improved by including the effect of sea surface temperature on cyclone-driven ocean mixing.

2. Stem cells and cancer

   Prostate tumours from a surprising source

Article de Monya Baker, publié le 1er Octobre 2009, dans Nature Reports Stem Cells.