Science Square

  • Issue 100 / July - August 2014



    Science Square

    The Fountain

    Supernova explosions generated in the lab
    J. Meinecke et al. Turbulent amplification of magnetic fields in laboratory laser-produced shock waves
    June 2014, Nature Physics.


    A supernova is the explosion of a massive star which releases a burst of radiation that can be as bright as 10 billion suns. Such a massive amount of radiation can shine throughout the entire universe for several light-years. Supernovas are triggered either when the fuel within a star ignites or when a star's core collapses under extreme gravitational forces. Supernovas have already taught us very important lessons about the history of the universe. For example, these explosions have provided solid evidence that the universe is expanding. Supernovas can also tell us a lot about how old stars die and how new stars are born. When a star goes through a supernova explosion, it leaves behind a skeleton made of expanding dust and gas that scientists call a remnant. These star-remnants spread around space. They might end up on earth or other planets, or they could form the energy source of a new star. Since the best way to understand supernovas is to actually explode a star, researchers recently developed a technique to simulate small-scale supernovas in a lab environment. To do this, scientists used lasers that are 60,000 billion times more powerful than a laser pointer. They focused the laser beams on a thin carbon rod inside a gas-filled chamber. The lasers heated the chamber to over 1 million degrees Celsius, which caused the carbon rod to explode and expand out through the low density gas - just like how exploding stars speed through space. The experiment revealed that as the blast passes through the grid, it becomes irregular and turbulent. They also noticed that the magnetic field was dramatically higher within the grid than without, suggesting that the magnetic field was amplified by the generated turbulence. The supernova system developed in this study holds the possibility of helping us better understand how the universe was formed and evolved, and could provide some insight into how magnetic fields were first created.

    Young blood: the fountain of youth?
    Villeda SA et al. Young blood reverses age-related impairments in cognitive function and synaptic plasticity in mice. June 2014, Nature Medicine.


    Sinha M. et al. Restoring systemic GDF11 levels reverses age-related dysfunction in mouse skeletal muscle. June 2014, Science.

    Two recent studies of lab mice showed that transfusions of blood from younger individuals reverse the effects of aging in their elders. One research group showed that neural damage of mice with age-related cognitive impairments could be reversed by such transfusions. Alternatively, injecting the younger plasma into the brain was also very effective at repairing neural damage. Another research group showed that blood from younger mice repaired age-related heart defects in older mice. Researchers further discovered that high levels of the protein GDF11, present in the blood of younger mice, were the key for rejuvenation. Researchers proposed that blood from younger mice contains molecules with anti-aging properties that awaken the stem cells of the brain and heart muscles and thus initiate the rejuvenation. These studies are incredibly encouraging for combating Alzheimer's disease, heart disease, and many other age-related diseases; however, a comprehensive set of clinical tests needs to be conducted before testing the effects in humans.

    "Chameleon" plant discovered
    Gianoli E. and Carrasco-Urra F. Leaf mimicry in a climbing plant Protects against herbivory. May 2014, Current Biology.

    Scientists thought for many years that camouflage and mimicry were only observed in the animal kingdom. A newly discovered wood vine in Chile, Boquila trifoliolata, has been found to transform its leaves to mimic a variety of host trees. B. trifoliolata is the first plant ever shown to imitate multiple hosts. This is a rare trait called "mimetic polymorphism" and it was only previously observed in butterflies. As B. trifoliolata climbs onto a tree's branches, it changes the color, size, shape, orientation, and even the vein patterns of its leaves to match the surrounding flora. When the same vine crosses over to a second tree, the size of its leaves can even increase 10 times to match the second host plant. According to scientists, mimicry may protect the vine from plant-eating herbivores such as weevils and leaf beetles. It is perplexing how a plant can distinguish between individual trees and keep changing its physical characteristics. Odors, chemicals, or microbes that are released form host plants are potential candidate mechanisms for this intriguing plant behavior.

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