Dark Tower - A Bridge to Nowhere - Near Open Cluster NGC 6231
The Dark Tower in the constellation of Scorpius is an elongated dark cloud of dust and gas embedded in a rich sea of stars. It is known as a cometary globule where intense UV radiation from very hot OB-type stars in NGC6231 (off the top edge of the image) sculpts the resulting columnar structure of the Dark Tower. The UV radiation is sufficiently strong to ionize hydrogen, producing an ominous pink glow around the top of the Dark Tower and similarly to ionize the background medium, such as the interesting “bridge to nowhere” of H-alpha light extending from the tip of the Dark Tower toward the left side of the image. There are several blue reflection nebula embedded within the Dark Tower. These structures are stellar nurseries. The Dark Tower is 40 light years across and 5,000 light years distant.
Credit: Don Goldman
Herbig-Haro 110, a geyser of hot gas from a newborn star, observed by the Hubble Space Telescope.
Human cortical neural stem cells
Cortical neurons are located in the cerebral cortex of the brain, a region responsible for memory, thought, language, and consciousness. Neural stem cells are “immature” cells committed to become neurons and helper cells of the brain. Neurons are the liaison between our brain and the world. When we eat a lemon, neurons connected to our taste buds tell the brain that it’s sour. Messages from the brain can also be sent elsewhere, as when neurons command muscles to contract while lifting a heavy object.
Image by Kimmy Lorrain, BrainCells, Inc.
Carlos F Turienzo
Our Sun is a main sequence star which actively fuses hydrogen into helium in its core. In certain regions of the Sun, the energy created by the hydrogen “burning” is carried to its surface by convection. However, intense magnetic fields in sunspots strangle the normal up-flow of energy from the interior, so energy is unable to reach the surface in these areas leaving the sunspot cooler and therefore darker than its surroundings. The strong magnetic fields in these convection zones promote cooling, thus the hot gas near the Sun’s surface contracts and sinks at speeds of up to 4,000 kilometers per hour. This drives an inward flow, like a planet-sized whirlpool. Of course, seeing behind the scenes in sunspots is not easy; the Sun below the photosphere is opaque and hidden. The only way to investigate the morphology and the structure of sunspots is through helioseismology. Using the Helioseismic and Magnetic Imager (HMI) on SDO, we can explore the solar interior by detecting natural sound waves on the Sun’s surface.
For more information:
- Detection of Emerging Sunspot Regions
- Local Helioseismology of Sunspots
- The Exploratorium’s Guide to Sunspots
- Sunspots and Solar Storms
Image Credit: NASA/SOHO/MDI/Alexander Kosovichev/Tom Bridgman
Exploring parametric trigonometric functions in polar coordinates.
(Image caption: This image shows the brain’s default mode network, where memory and sensory information are stored. Credit: Marcus Raichle, Washington University)
For many years, the focus of brain mapping was to examine changes in the brain that occur when people are attentively engaged in an activity. No one spent much time thinking about what happens to the brain when people are doing very little.
But Marcus Raichle, a professor of radiology, neurology, neurobiology and biomedical engineering at Washington University in St. Louis, has done just that. In the 1990s, he and his colleagues made a pivotal discovery by revealing how a specific area of the brain responds to down time.
"A great deal of meaningful activity is occurring in the brain when a person is sitting back and doing nothing at all," says Raichle, who has been funded by the National Science Foundation (NSF) Division of Behavioral and Cognitive Sciences in the Directorate for Social, Behavioral and Economic Sciences. "It turns out that when your mind is at rest, dispersed brain areas are chattering away to one another."
The results of these discoveries now are integral to studies of brain function in health and disease worldwide. In fact, Raichle and his colleagues have found that these areas of rest in the brain—the ones that ultimately became the focus of their work—often are among the first affected by Alzheimer’s disease, a finding that ultimately could help in early detection of this disorder and a much greater understanding of the nature of the disease itself.
For his pioneering research, Raichle this year was among those chosen to receive the prestigious Kavli Prize, awarded by The Norwegian Academy of Science and Letters. It consists of a cash award of $1 million, which he will share with two other Kavli recipients in the field of neuroscience.
His discovery was a near accident, actually what he calls “pure serendipity.” Raichle, like others in the field at the time, was involved in brain imaging, looking for increases in brain activity associated with different tasks, for example language response.
In order to conduct such tests, scientists first needed to establish a baseline for comparison purposes which typically complements the task under study by including all aspects of the task, other than just the one of interest.
"For example, a control task for reading words aloud might be simply viewing them passively," he says.
In the Raichle laboratory, they routinely required subjects to look at a blank screen. When comparing this simple baseline to the task state, Raichle noticed something.
"We didn’t specify that you clear your mind, we just asked subjects to rest quietly and don’t fall asleep," he recalls. "I don’t remember the day I bothered to look at what was happening in the brain when subjects moved from this simple resting state to engagement in an attention demanding task that might be more involved than simply increases in brain activity associated with the task.
"When I did so, I observed that while brain activity in some parts of the brain increased as expected, there were other areas that actually decreased their activity as if they had been more active in the ‘resting state,"’ he adds. "Because these decreases in brain activity were so dramatic and unexpected, I got into the habit of looking for them in all of our experiments. Their consistency both in terms of where they occurred and the frequency of their occurrence—that is, almost always—really got my attention. I wasn’t sure what was going on at first but it was just too consistent to not be real."
These observations ultimately produced ground-breaking work that led to the concept of a default mode of brain function, including the discovery of a unique fronto-parietal network in the brain. It has come to be known as the default mode network, whose regions are more active when the brain is not actively engaged in a novel, attention-demanding task.
"Basically we described a core system of the brain never seen before," he says. "This core system within the brain’s two great hemispheres increasingly appears to be playing a central role in how the brain organizes its ongoing activities"
The discovery of the brain’s default mode caused Raichle and his colleagues to reconsider the idea that the brain uses more energy when engaged in an attention-demanding task. Measurements of brain metabolism with PET (positron emission tomography) and data culled from the literature led them to conclude that the brain is a very expensive organ, accounting for about 20 percent of the body’s energy consumption in an adult human, yet accounting for only 2 percent of the body weight.
"The changes in activity associated with the performance of virtually any type of task add little to the overall cost of brain function," he continues. "This has initiated a paradigm shift in brain research that has moved increasingly to studies of the brain’s intrinsic activity, that is, its default mode of functioning."
Raichle, whose work on the role of this intrinsic brain activity on facets of consciousness was supported by NSF, is also known for his research in developing and using imaging techniques, such as positron emission tomography, to identify specific areas of the brain involved in seeing, hearing, reading, memory and emotion.
In addition, his team studied chemical receptors in the brain, the physiology of major depression and anxiety, and has evaluated patients at risk for stroke. Currently, he is completing research studying what happens to the brain under anesthesia.
"The brain is capable of so many things, even when you are not conscious," Raichle says. "If you are unconscious, the organization of the brain is maintained, but it is not the same as being awake."
More detailed shots of butterfly wing scales (Part 3). In this case a Monarch Butterfly.
This Week in Chemistry: the Nobel prize in chemistry was awarded for work that allows optical microscopes to view individual molecules, whilst elsewhere researchers wrote gold characters inside cells, and developed a cancer drug delivery system based on molecules found in green tea. More information here: http://goo.gl/qXFPhj
Explanation: What caused this mess? Some type of star exploded to create the unusually shaped nebula known as Kepler’s supernova remnant, but which type? Light from the stellar explosion that created this energized cosmic cloud was first seen on planet Earth in October 1604, a mere four hundred years ago. The supernova produced a bright new star in early 17th century skies within the constellation Ophiuchus. It was studied by astronomer Johannes Kepler and his contemporaries, with out the benefit of a telescope, as they searched for an explanation of the heavenly apparition. Armed with a modern understanding of stellar evolution, early 21st century astronomers continue to explore the expanding debris cloud, but can now use orbiting space telescopes to survey Kepler’s supernova remnant (SNR) across the spectrum. Recent X-ray data and images of Kepler’s supernova remnant taken by the orbiting Chandra X-ray Observatory has shown relative elemental abundances more typical of a Type Ia supernova, indicating that the progenitor was awhite dwarf star that exploded when it accreted too much material and went over Chandrasekhar’s limit. About 13,000 light years away, Kepler’s supernova represents the most recent stellar explosion seen to occurwithin our Milky Way galaxy.
THAT IS BADASS.
"New technology developed by MIT and several other institutions could make it possible to track the position of nano particles as they move within the body or inside a cell."
Colorless powellite with stilbite from the Nasik district in Maharashtra, India