Tuesday, January 31, 2017
The lined chiton is a species of chiton from the North Pacific. It has been recorded from intertidal and subtidal waters to a depth of 30 to 90 m. T. lineata often occurs on rocks that are encrusted by coralline algae; presumably this is what their coloration is intended to camouflage against. If knocked from its substrate, T. lineata will contract into a ball in order to protect its vulnerable ventral side, similar to many isopods. Coralline algae are also the major food item of T. lineata.
Photo via Wikipedia Commons
The Fibonacci sequence is a series of numbers where a number is found by adding up the two numbers before it. Starting with 0 and 1, the sequence goes 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, and so forth.
Named after Fibonacci, also known as Leonardo of Pisa or Leonardo Pisano, Fibonacci numbers were first introduced in his Liber abaci in 1202. The son of a Pisan merchant, Fibonacci traveled widely and traded extensively. Math was incredibly important to those in the trading industry, and his passion for numbers was cultivated in his youth.
Knowledge of numbers is said to have first originated in the Hindu-Arabic arithmetic system, which Fibonacci studied while growing up in North Africa. Prior to the publication of Liber abaci, the Latin-speaking world had yet to be introduced to the decimal number system. He wrote many books about geometry, commercial arithmetic and irrational numbers. He also helped develop the concept of zero.
Monday, January 30, 2017
MIT neuroscientists have discovered that brain cells called glial cells play a critical role in controlling appetite and feeding behavior. In a study of mice, the researchers found that activating these cells stimulates overeating, and that when the cells are suppressed, appetite is also suppressed.
The findings could offer scientists a new target for developing drugs against obesity and other appetite-related disorders, the researchers say. The study is also the latest in recent years to implicate glial cells in important brain functions. Until about 10 years ago, glial cells were believed to play more of a supporting role for neurons.
#neuroscience #appetite #obesity #eatingdisorders #glialcells
Like an illustration in a galactic Just So Story, the Elephant's Trunk Nebula winds through the emission nebula and young star cluster complex IC 1396, in the high and far off constellation of Cepheus. Also known as vdB 142, the cosmic elephant's trunk is over 20 light-years long. This colorful close-up view includes image data from a narrow band filter that transmits the light from ionized hydrogen atoms in the region.
The resulting composite highlights the bright swept-back ridges that outline pockets of cool interstellar dust and gas. Such embedded, dark, tendril-shaped clouds contain the raw material for star formation and hide protostars within. Nearly 3,000 light-years distant, the relatively faint IC 1396 complex covers a large region on the sky, spanning over 5 degrees. This dramatic scene spans a 1 degree wide field, about the size of 2 Full Moons.
Image & info via APODhttps://apod.nasa.gov/apod/astropix.html
Image Credit & Copyright: Stephen Leshin
Saturday, January 28, 2017
“Could you repeat that?” The reason you may have to say something twice when talking to older family members at Thanksgiving dinner may not be because of their hearing. Researchers at the University of Maryland have determined that something is going on in the brains of typical older adults that causes them to struggle to follow speech amidst background noise, even when their hearing would be considered normal on a clinical assessment.
In an interdisciplinary study published by the Journal of Neurophysiology, researchers Samira Anderson, Jonathan Z. Simon, and Alessandro Presacco found that adults aged 61–73 with normal hearing scored significantly worse on speech understanding in noisy environments than adults aged 18–30 with normal hearing. The researchers are all associated with the UMD’s Brain and Behavior Initiative.
“Evidence of degraded representation of speech in noise, in the aging midbrain and cortex” is part of ongoing research into the so-called cocktail party problem, or the brain’s ability to focus on and process a particular stream of speech in the middle of a noisy environment. This research brings together the fields of hearing and speech science, neuroscience and cognitive science, electrical engineering, biology, and systems science.
The study subjects underwent two different kinds of scans to measure their brains’ electrical activity while they listened to people talk. The researchers were able to see what the subjects’ brains were up to when asked what someone was saying, both in a quiet environment and amidst a level of noise. The researchers studied two areas of the brain. They looked at the more ‘ancestral’ midbrain area, which most vertebrate animals—all the way down to fish—have, and which does basic processing of all sounds. They also looked at the cortex, which is particularly large in humans and part of which specializes in speech processing.
In the younger subject group, the midbrain generated a signal that matched its task in each case—looking like speech in the quiet environment, and speech clearly discernible against a noisy background in the noise environment. But in the older subject group, the quality of the response to the speech signal was degraded even when in the quiet environment, and the response was even worse in the noisy environment.
“For older listeners, even when there isn’t any noise, the brain is already having trouble processing the speech,” said Simon.
Neural signals recorded from cortex showed that younger adults could process speech well in a relatively short amount of time. But the auditory cortex of older test subjects took longer to represent the same amount of information.
Why is this the case? “Part of the comprehension problems experienced by older adults in both quiet and noise conditions could be linked to age-related imbalance between excitatory and inhibitory neural processes in the brain,” Presacco said. “This imbalance could impair the brain’s ability to correctly process auditory stimuli and could be the main cause of the abnormally high cortical response observed in our study.”
“Older people need more time to figure out what a speaker is saying,” Simon noted. “They are dedicating more of their resources and exerting more effort than younger adults when they are listening to speech.”
“Often we will hear an older person say, ‘I can hear you, I just can’t understand you,” said Anderson. “This research gives us new insight into why that is the case.”
Atrial fibrillation is a type of arrhythmia in which the upper chambers of the heart (the atria) beat erratically. This erratic beating can be extremely fast, reaching more than 300 beats per minute, which prevents blood from circulating freely from the atria into the lower chambers of the heart, known as the ventricles. Atrial fibrillation can be a one-time event, a recurring issue or a permanent condition.
Atrial fibrillation (also called AFib or AF) is a quivering or irregular heartbeat (arrhythmia) that can lead to blood clots, stroke, heart failure and other heart-related complications.
What happens during AFib?
Normally, your heart contracts and relaxes to a regular beat. In atrial fibrillation, the upper chambers of the heart (the atria) beat irregularly (quiver) instead of beating effectively to move blood into the ventricles.
If a clot breaks off, enters the bloodstream and lodges in an artery leading to the brain, a stroke results. About 15–20 percent of people who have strokes have this heart arrhythmia. This clot risk is why patients with this condition are put on blood thinners.
Even though untreated atrial fibrillation doubles the risk of heart-related deaths and is associated with a 5-fold increased risk for stroke, many patients are unaware that AFib is a serious condition.
Know the symptoms:http://www.heart.org/HEARTORG/Conditions/Arrhythmia/AboutArrhythmia/What-are-the-Symptoms-of-Atrial-Fibrillation-AFib-or-AF_UCM_423777_Article.jsp#.WIYEYbnn670
Get the right treatment:http://www.heart.org/HEARTORG/Conditions/Arrhythmia/AboutArrhythmia/Treatment-and-Prevention-of-Atrial-Fibrillation_UCM_423778_Article.jsp#.WIYEe7nn670
Reduce risks for stroke and heart failure:http://www.heart.org/HEARTORG/Conditions/Arrhythmia/AboutArrhythmia/Prevention-Strategies-for-Atrial-Fibrillation-AFib-or-AF_UCM_423784_Article.jsp#.WIYEpbnn670
Watch & learn:http://watchlearnlive.heart.org/CVML_Player.php?moduleSelect=atrfib
Animation by Biosense Webster