Science Square

  • Issue 97 / January - February 2014

    Science Square

    The Fountain

    A galaxy rapidly forming stars 700 million years after the Big Bang at redshift 7.51
    Finkelstein S.L et al., Nature, October 2013

    Astronomers have recently spotted a faint ray of light using the Hubble Space Telescope, a ten-meter telescope at Keck Observatory, located at the summit of Mauna Kea, a dormant volcano in Hawaii. Analysis of light showed that it was a galaxy formed 13.1 billion years ago, which is only 700 million years after the Big Bang, when our universe came into existence. This is so far back in time, it would be about 8 billion years before our sun was born. The new galaxy is called z8_GND_5296, and it is the oldest and most distant galaxy ever discovered. Because the universe is expanding, the lights coming from distant objects would be stretched, and their wavelengths changed, as they travel through the expanding universe. This phenomenon is called Redshift. It makes visible light look redder, and redshift increases proportionally with the distance to an object. Lights coming from z8_GND_5296 looked more redshifted than anyone had seen before. More detailed analyses showed that the mass of gz8_GND_5296's stars was equivalent to 1 billion suns, which is approximately 50 times less than the Milky Way's stellar mass. Even more surprisingly, the new galaxy is found to have an unusually high star-formation rate. This rate is typically calculated by how much raw hydrogen the galaxy yearly converts into new stars. gz8_GND_5296 converts hydrogen 300 times the mass of our sun, while the Milky Way produces 1 or 2 solar masses per year. One of the explanations for this extraordinary star-formation rate is that the early galaxies contained or drew in much more gas than scientists expected. The search for distant galaxies aims to find the very first galaxies formed after the Big Bang, perhaps the ones that produced the first natural elements. To this end, NASA plans to launch the James Webb Space Telescope (JWST) in 2018. JWST will reside in an orbit 1.5 million km from the earth and hopefully it will help astronomers to look further and further back into the origins of the Milky Way, and ultimately, the history of our universe.

    Vast Freshwater Reserves Found Under Ocean
    Offshore fresh groundwater reserves as a global phenomenon.
    Post V.E.A et al., Nature, December 2013

    As earth's population rises, we face a serious problem of fresh water supplies. The United Nations predicts that half of the world will be struggling to find clean, fresh sources of water by 2030. Luckily, Australian scientists discovered huge freshwater reserves, and in the most unexpected place: under the ocean floor. Newly discovered reserves are estimated to contain 500,000 cubic kilometers of low-salinity water, located off the coast of South Africa, North America, Australia, and China. This vast reserve is approximately 100 times greater than the volume of the fresh water used since the beginning of the 1900s. This water reserve is thought to develop earlier in Earth's history, perhaps over thousands of years, when oceans were not that deep and when the coastline was further out. Scientists hypothesize that rainwater leaked through the ground and had created these fresh water aquifers beneath layers of porous rock and/or soil. Around 20,000 years ago, the polar ice caps began to melt and these regions were covered by ocean. Fortunately, layers of either clay or sediment seemed to protect the reservoirs from salty contamination: the salinity of this water is low enough to be readily transformed into drinkable water. These water reserves can be extracted by constructing drilling platforms, either at sea or from the mainland, close to aquifers. However, drilling projects are usually very controversial due to environmental and economic costs. Scientists are currently seeking alternative, more environment-friendly ways to use these reserves. Nonetheless, mankind may have found a new vital water resource for the future.

    Crows Don't Forget a Face; Crow Intelligence Decoded
    Abstract rule neurons in the endbrain support intelligent behavior in corvid songbirds.
    Veit L. and Nieder A., Nature Communications November 2013

    Scientists have long suspected that members of the corvids – a family of birds that includes ravens, crows and magpies – are extraordinarily intelligent. They make and use tools, remember multiple feeding locations, and exhibit highly social behaviors. Last year, scientists even demonstrated that crows captured in Seattle would never forget the face of their abductor and they would still taunt and dive-bomb the threatening face several years after the incident. To understand the mechanism of crows' amazing face recognition process, neurobiologists designed an experiment, in which they trained the crows to perform memory tests on a computer. The crows were first shown an image and shortly afterwards, they had to select one of two test images on a touchscreen, using their beaks, based on switching behavioral rules. One of the test images was identical to the first image; the other one was a different image. Sometimes, the rule of the game was to select the very same image, and sometimes it was to select a different one. Remarkably, the crows were able to carry out both tasks and to switch between them almost perfectly. These tasks require a high level of concentration and mental flexibility that few animal species can manage – they even require a great effort for humans. By recording single-unit neuronal activity from an association area of the crow's brain, known as the nidopallium caudolaterale (NCL), the researchers were often able to guess which rule the crow was following, even before the crow made its choice. The cerebral cortex in human brain is very large and it is thought to be home to complex cognitive functions including face recognition. However, since a bird's cerebral cortex is much smaller than humans, people long thought that birds could not perform intelligent tasks. This study shows that birds use a unique non-cortical brain region, nidopallium caudolaterale (NCL), to sort sensory information and decide how to react.


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