Elucidate

Blog just for my science interests, keeping my personal life outta this one. Nothing I post is my own unless otherwise stated.

sixpenceee:

Informal infographic depicting evolution 

(via quantumaniac)


  The Alnitak Region by Grady Owens

The Alnitak Region by Grady Owens

(via afro-dominicano)

neurosciencestuff:

A long childhood feeds the hungry human brain

A five-year old’s brain is an energy monster. It uses twice as much glucose (the energy that fuels the brain) as that of a full-grown adult, a new study led by Northwestern University anthropologists has found.

The study helps to solve the long-standing mystery of why human children grow so slowly compared with our closest animal relatives.

It shows that energy funneled to the brain dominates the human body’s metabolism early in life and is likely the reason why humans grow at a pace more typical of a reptile than a mammal during childhood.

Results of the study will be published the week of Aug. 25 in the journal Proceedings of the National Academy of Sciences.

"Our findings suggest that our bodies can’t afford to grow faster during the toddler and childhood years because a huge quantity of resources is required to fuel the developing human brain," said Christopher Kuzawa, first author of the study and a professor of anthropology at Northwestern’s Weinberg College of Arts and Sciences. "As humans we have so much to learn, and that learning requires a complex and energy-hungry brain."

Kuzawa also is a faculty fellow at the Institute for Policy Research at Northwestern.

The study is the first to pool existing PET and MRI brain scan data — which measure glucose uptake and brain volume, respectively — to show that the ages when the brain gobbles the most resources are also the ages when body growth is slowest. At 4 years of age, when this “brain drain” is at its peak and body growth slows to its minimum, the brain burns through resources at a rate equivalent to 66 percent of what the entire body uses at rest.

The findings support a long-standing hypothesis in anthropology that children grow so slowly, and are dependent for so long, because the human body needs to shunt a huge fraction of its resources to the brain during childhood, leaving little to be devoted to body growth. It also helps explain some common observations that many parents may have.

"After a certain age it becomes difficult to guess a toddler or young child’s age by their size," Kuzawa said. "Instead you have to listen to their speech and watch their behavior. Our study suggests that this is no accident. Body growth grinds nearly to a halt at the ages when brain development is happening at a lightning pace, because the brain is sapping up the available resources."

It was previously believed that the brain’s resource burden on the body was largest at birth, when the size of the brain relative to the body is greatest. The researchers found instead that the brain maxes out its glucose use at age 5. At age 4 the brain consumes glucose at a rate comparable to 66 percent of the body’s resting metabolic rate (or more than 40 percent of the body’s total energy expenditure).

"The mid-childhood peak in brain costs has to do with the fact that synapses, connections in the brain, max out at this age, when we learn so many of the things we need to know to be successful humans," Kuzawa said.

"At its peak in childhood, the brain burns through two-thirds of the calories the entire body uses at rest, much more than other primate species," said William Leonard, co-author of the study. "To compensate for these heavy energy demands of our big brains, children grow more slowly and are less physically active during this age range. Our findings strongly suggest that humans evolved to grow slowly during this time in order to free up fuel for our expensive, busy childhood brains."

neurosciencestuff:

Train your heart to protect your mind

Exercising to improve our cardiovascular strength may protect us from cognitive impairment as we age, according to a new study by researchers at the University of Montreal and its affiliated Institut universitaire de gératrie de Montréal Research Centre. “Our body’s arteries stiffen with age, and the vessel hardening is believed to begin in the aorta, the main vessel coming out of the heart, before reaching the brain. Indeed, the hardening may contribute to cognitive changes that occur during a similar time frame,” explained Claudine Gauthier, first author of the study. “We found that older adults whose aortas were in a better condition and who had greater aerobic fitness performed better on a cognitive test. We therefore think that the preservation of vessel elasticity may be one of the mechanisms that enables exercise to slow cognitive aging.”

The researchers worked with 31 young people between the ages of 18 and 30 and 54 older participants aged between 55 and 75. This enabled the team to compare the older participants within their peer group and against the younger group who obviously have not begun the aging processes in question. None of the participants had physical or mental health issues that might influence the study outcome. Their fitness was tested by exhausting the participants on a workout machine and determining their maximum oxygen intake over a 30 second period. Their cognitive abilities were assessed with the Stroop task. The Stroop task is a scientifically validated test that involves asking someone to identify the ink colour of a colour word that is printed in a different colour (e.g. the word red could be printed in blue ink and the correct answer would be blue). A person who is able to correctly name the colour of the word without being distracted by the reflex to read it has greater cognitive agility.

The participants undertook three MRI scans: one to evaluate the blood flow to the brain, one to measure their brain activity as they performed the Stroop task, and one to actually look at the physical state of their aorta. The researchers were interested in the brain’s blood flow, as poorer cardiovascular health is associated with a faster pulse wave,at each heartbeat which in turn could cause damage to the brain’s smaller blood vessels. “This is first study to use MRI to examine participants in this way,” Gauthier said. “It enabled us to find even subtle effects in this healthy population, which suggests that other researchers could adapt our test to study vascular-cognitive associations within less healthy and clinical populations.”

The results demonstrated age-related declines in executive function, aortic elasticity and cardiorespiratory fitness, a link between vascular health and brain function, and a positive association between aerobic fitness and brain function. “The link between fitness and brain function may be mediated through preserved cerebrovascular reactivity in periventricular watershed areas that are also associated with cardiorespiratory fitness,” Gauthier said. “Although the impact of fitness on cerebral vasculature may however involve other, more complex mechanisms, overall these results support the hypothesis that lifestyle helps maintain the elasticity of arteries, thereby preventing downstream cerebrovascular damage and resulting in preserved cognitive abilities in later life.”

space-facts:

Pluto is the second closest dwarf planet to the Sun and is also the second most massive dwarf planet. It is possible that either Pluto is the largest dwarf planet but Pluto’s atmosphere makes it is difficult to determine a precise size. Pluto was discovered on February 18th, 1930 by Clyde W. Tombaugh at the Lowell Observatory.

Image credit: NASA, based on the planet profiles by Space Plasma

(via spaceplasma)

Slippin’ And A-Slidin’ - Different Types of Earthquake Faults

Image BX1676 (Types of Fault Lines)

Image BC5953 (Normal Earthquake Fault)

Image BV9643 (Normal Fault) 

Image 7J2476 (Reverse Fault)

Image BZ0972 (Thrust Fault)

Image SK5591 (San Andreas Fault)

Images showing the different types of earthquake faults. Each is differentiated by the relative position of the fault plane. A normal fault occurs where the crust is being pulled apart, which extends the earth’s crust. The Basin and Range Province in North America and the East African Rift Zone are two examples of this. A reverse fault also called a thrust fault, squeezes the earth’s crust, pushing two blocks of on top of each other. A good example of this would be mountain ranges like the Himalayas and Rocky Mountains. The 1994 Northridge quake occurred along a thrust fault that, at the time, no one knew existed. A strike slip fault occurs when plates of the earth’s crust slide passed each other. Both the San Andreas and Anatolian Faults are strike slip. 

© Science Source

(via sciencesourceimages)

fuckyeahfluiddynamics:

Yesterday we discussed some of the basic mechanics of a frisbee in flight. Although frisbees do generate lift similarly to a wing, they do have some unique features. You’ve probably noticed, for example, that the top surface of a frisbee has several raised concentric rings. These are not simply decoration! Instead the rings disrupt airflow at the surface of the frisbee. This actually creates a narrow region of separated flow, visible in region B on the left oil-flow image. Airflow reattaches to the frisbee in the image after the second black arc, and the boundary layer along region C remains turbulent and attached for the remaining length of the frisbee. Keeping the boundary layer attached over the top surface ensures low pressure so that the disk has plenty of lift and remains aerodynamically stable in flight. A smooth frisbee would be much harder to throw accurately because its flight would be very sensitive to angle of attack and likely to stall. (Image credits: J. Potts and W. Crowther; recommended papers by: V. Morrison and R. Lorentz)

(via scinerds)

Traces of One of Universe’s First Stars Detected

An ancient star in the halo surrounding the Milky Way galaxy appears to contain traces of material released by the death of one of the universe’s first stars, a new study reports.

The chemical signature of the ancient star suggests that it incorporated material blasted into space by a supernova explosion that marked the death of a huge star in the early universe — one that may have been 200 times more massive than the sun.

"The impact of very-massive stars and their explosions on subsequent star formation and galaxy formation should be significant," lead author Wako Aoki, of the National Astronomical Observatory of Japan, told Space.com by email.

(via afro-dominicano)

astrodidact:

Researchers have finally discovered the source of fungal infections that are responsible for one-third of AIDS-related deaths in Southern California. The fungus, Cryptococcus gattii, grows on trees via ScienceAlert
http://phys.org/news/2014-08-fungus-deadly-aids-patients-trees.html

astrodidact:

Researchers have finally discovered the source of fungal infections that are responsible for one-third of AIDS-related deaths in Southern California. The fungus, Cryptococcus gattii, grows on trees via ScienceAlert

http://phys.org/news/2014-08-fungus-deadly-aids-patients-trees.html