Friday, March 30, 2018
What are those red clouds surrounding the Andromeda galaxy? This galaxy, M31, is often imaged by planet Earth-based astronomers. As the nearest large spiral galaxy, it is a familiar sight with dark dust lanes, bright yellowish core, and spiral arms traced by clouds of bright blue stars.
A mosaic of well-exposed broad and narrow-band image data, this colorful portrait of our neighboring island universe offers strikingly unfamiliar features though, faint reddish clouds of glowing ionized hydrogen gas in the same wide field of view.
These ionized hydrogen clouds surely lie in the foreground of the scene, well within our Milky Way Galaxy. They are likely associated with the pervasive, dusty interstellar cirrus clouds scattered hundreds of light-years above our own galactic plane.
Image & info via APODhttps://apod.nasa.gov/apod/astropix.html
Image Credit & Copyright: Daniel López / IAC
Researchers from the McGill Group for Suicide Studies, based at the Douglas Mental Health University Institute and McGill University’s Department of Psychiatry, have published research in the American Journal of Psychiatry that suggests that the long-lasting effects of traumatic childhood experiences, like severe abuse, may be due to an impaired structure and functioning of cells in the anterior cingulate cortex. This is a part of the brain which plays an important role in the regulation of emotions and mood.
The researchers believe that these changes may contribute to the emergence of depressive disorders and suicidal behaviour.
Crucial insulation for nerve fibers builds up during first two decades of Life
For the optimal function and organization of the brain, electrical signals used by neurons may need to travel over long distances to communicate with cells in other regions. The longer axons of this kind are generally covered by a fatty coating called myelin. Myelin sheaths protect the axons and help them to conduct electrical signals more efficiently. Myelin builds up progressively (in a process known as myelination) mainly during childhood, and then continue to mature until early adulthood.
Earlier studies had shown significant abnormalities in the white matter in the brains of people who had experienced child abuse. (White matter is mostly made up of thousands of myelinated nerve fibres stacked together.) But, because these observations were made by looking at the brains of living people using MRI, it was impossible to gain a clear picture of the white matter cells and molecules that were affected.
To gain a clearer picture of the microscopic changes which occur in the brains of adults who have experienced child abuse, and thanks to the availability of brain samples from the Douglas-Bell Canada Brain Bank (where, as well as the brain matter itself there is a lot of information about the lives of their donors) the researchers were able to compare post-mortem brain samples from three different groups of adults: people who had committed suicide who suffered from depression and had a history of severe childhood abuse (27 individuals); people with depression who had committed suicide but who had no history of being abused as children (25 individuals); and brain tissue from a third group of people who had neither psychiatric illnesses nor a history of child abuse (26 people).
Impaired neural connectivity may affect the regulation of emotions
The researchers discovered that the thickness of the myelin coating of a significant proportion of the nerve fibers was reduced ONLY in the brains of those who had suffered from child abuse. They also found underlying molecular alterations that selectively affect the cells that are responsible for myelin generation and maintenance. Finally, they found increases in the diameters of some of the largest axons among only this group and they speculate that together, these changes may alter functional coupling between the cingulate cortex and subcortical structures such as the amygdala and nucleus accumbens (areas of the brain linked respectively to emotional regulation and to reward and satisfaction) and contribute to altered emotional processing in people who have been abused during childhood.
The researchers conclude that adversity in early life may lastingly disrupt a range of neural functions in the anterior cingulate cortex. And while they don’t yet know where in the brain and when during development, and how, at a molecular level these effects are sufficient to have an impact on the regulation of emotions and attachment, they are now planning to explore this in further research.
Source: Corina Marinescu
Thursday, March 29, 2018
The astronomy community is buzzing over radio telescope measurements that could indicate radiation from the universe's first stars, a mere 180 million years after the Big Bang. The signal, detected by radio antennae situated in the Australian desert, does not match theoretical predictions of what those early stellar signatures would look like.
That's both exciting and worrying: It could mean that hydrogen atoms in the early universe were interacting with cold, lightweight particles of dark matter. But it also could mean that the signal is the result of instrument calibration errors or other factors. Other radio observatories should be able to chime in over the next couple of years to confirm or refute the new results.
Journal article (under paywall):https://www.nature.com/articles/nature25792
This handout photo released by Nature on February 28, 2018 shows a timeline of the universe, updated to show when the first stars emerged reflecting a recent discovery by researchers at Arizona State University that the first stars emerged by 180 million years after the Big Bang.
Wednesday, March 28, 2018
The striking X in this lunarscape is easily visible in binoculars or a small telescope, but not too many have seen it. The catch is, this lunar X is fleeting and only apparent in the hours before the Moon's first quarter phase. Along the shadow line between lunar day and night, the X illusion is produced by a configuration of craters seen here toward the left, Blanchinus, La Caille and Purbach.
Near the Moon's first quarter phase, an astronaut standing close to the craters' position would see the slowly rising Sun very near the horizon. Temporarily, crater walls would be in sunlight while crater floors would still be in darkness. Seen from planet Earth, contrasting sections of bright walls against the dark floors by chance look remarkably like an X. This sharp image of the Lunar X was captured on February 22nd. For extra credit, sweep your gaze along the lunar terminator and you can also spot the Lunar V.
Image & info via APODhttps://apod.nasa.gov/apod/astropix.html
Image Credit & Copyright: Henrik Adamsson