Science Square

  • Issue 102 / November - December 2014



    Science Square

    The Fountain

    Newly Discovered Particle Is Both Matter and Antimatter
    Observing Majorana fermions in the ferromagnetic atomic chains on a superconductor.
    Nadj-Perge et al. Science, October 2014.

    In the universe, matter and antimatter particles are always produced as a pair and, if they come in contact, they destroy each other in a flash of energy. In 1937, an Italian theoretical physicist named Ettore Majorana had proposed that there can be unique exceptions to this rule: a stable particle could exist in nature that is both matter and antimatter. Scientists have been looking for that indefinable particle, also known as the “Majorana fermion," for seventy years. A group of researchers recently reported that they were able to detect the Majorana particle which behaves simultaneously like matter and antimatter. Researchers designed an experimental system allowing them to observe an emergent particle inside a material. They first generated an extended chain of pre magnetic iron atoms on a superconductor made of lead. Then, they cooled the material to -272 C, just about one point above absolute zero, and monitored it using a giant two-story-tall scanning-tunneling microscope, which can track electrical signal changes with very high precision. Finally, they were able to capture a glowing image of an electrically neutral particle at the ends of atomically thin iron wires. The Majorana particle was surprisingly stable and the opposing properties make the particle neutral so that it interacts very weakly with its environment. The discovery of the Majorana particle has exciting implications for several areas of modern physics, engineering, and astrophysics. For example, Majorana particles are very similar to neutrinos, as they both have very weak interactions with the matter. Neutrinos are thought to make up most of the dark matter that fill the Cosmos. Perhaps, neutrinos are simply Majorana-like particles and Majorana particles are also a candidate for what dark matter is. As an industrial application, Majorana particles can be utilized in quantum computing which aims to create computers to handle incalculable systems. The current quantum computing technology uses electrons, but they are known to be very unstable due to high interaction rates with surrounding materials. However, since Majorana particles are neutral and highly stable, they can be engineered into a variety of materials to produce more reliable and powerful quantum computing applications.

    The Bitter Side of Artificial Sweeteners
    Artificial sweeteners induce glucose intolerance by altering the gut's microbiota
    Suez J. et al. Nature, September 2014.

    There have been conflicting and confusing findings about the health effects of artificial sweeteners over the past several decades. Some studies found that they cause weight loss and others found the exact opposite. Some studies linked them to diabetes and other studies argued otherwise. A recent study provided a series of experimental evidences that artificial sweeteners disrupt the body's ability to regulate blood sugar, and thus may cause metabolic diseases and diabetes. Researchers, using animal models and human studies, found that sweeteners significantly alter the gut's microbiome - the collective name of bacterial colonies living in our intestines. The composition of our gut microflora plays a critical role protecting us from pathogenic bacteria, the metabolism of indigestible components of our diet, and modulating development and regulation of the immune system. Sweeteners - in the form of saccharin, sucralose, or aspartame - are found to alter the mix of microbes in our intestines and consequently change how our bodies metabolize glucose. Constant use of sweeteners in mice and human test groups caused typical glucose intolerance symptoms in which glucose levels rose higher after eating and declined more slowly than expected. Glucose intolerance can ultimately lead to serious illnesses like metabolic syndrome and Type 2 diabetes. Although this study will cause a lot of discussions and headaches in the food industry, the link identified between microbiome and glucose intolerance will definitely inspire novel therapeutic approaches to metabolic disorders such as diabetes.

    Brainy Fingertips
    Edge-orientation processing in first-order tactile neurons
    Pruszynski JA and Johansson RS. Nature Neuroscience, August 2014

    A new study found that neurons in human skin are able to perform advanced calculations that scientists thought only the brain was capable of performing. A group of sensory neurons that extend into the skin and record touch are called first-order neurons in the tactile system. Each nerve ending branches in the skin to form about 5mm2 elliptical receptive field, with up to 8 highly sensitive zones that are unevenly distributed within the field. It turns out that these neurons not only transmit information about when and how intensely an object is touched to the brain, but they also send complex information about the touched object's shape. Researchers found that the sensitivity of individual neurons to the shape of an object depends on the layout of the neuron's highly-sensitive zones in the skin. Computations that require untangling geometric shape information are classified as feature extraction computations in neuroscience and are typically attributed to the immensely complex circuits of the cerebral cortex. This study showed that neuronal populations localized outside of the brain, such as first-order tactile neurons, can have advanced processing capacity similar to brain neurons. These results can also potentially improve treatments for nerve injury and rehabilitation, as scientists previously assumed that the cerebral cortex was doing all the work.

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