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Images Capture Split Personality of Dense Suspensions

By Guest PostApril 9, 2012Sciencedna microarray, drop forms, heinrich jaeger, jeffrey morris, marc miskin, mathematical model, nozzle diameter, particle, phenomena, steve koppes, university of chicago, viscosity, viscous, viscous liquids, viscous mixture, zirconium dioxide

Stir lots of small particles into water, and the resulting thick mixture appears highly viscous. When this dense suspension slips through a nozzle and forms a droplet, however, its behavior momentarily reveals a decidedly non-viscous side. University of Chicago physicists recorded this surprising behavior in laboratory experiments using high-speed photography, which can capture action taking place in one hundred-thousandths of a second or less.

UChicago graduate student Marc Miskin and Heinrich Jaeger, the William J. Friedman and Alicia Townsend Friedman Professor in Physics, expected that the dense suspensions in their experiments would behave strictly like viscous liquids, which tend to flow less freely than non-viscous liquids. Viscosity certainly does matter as the particle-laden liquid begins to exit the nozzle, but not at the moment where the drop’s thinning neck breaks in two. (more…)

12-Mile-High Martian Dust Devil Caught in Act

By Guest PostApril 6, 2012Scienceamazonis planitia, dust devil, earth, hirise camera, mars reconnaissance orbiter, martian dust devil, martian surface, meteorite impact, NASA, northern mars, northern summer solstice, plume, red planet, tucson, university of arizona

A Martian dust devil roughly 12 miles high (20 kilometers) was captured whirling its way along the Amazonis Planitia region of Northern Mars on March 14. It was imaged by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter. Despite its height, the plume is little more than three-quarters of a football field wide (70 yards, or 70 meters).

Dust devils occur on Earth as well as on Mars. They are spinning columns of air, made visible by the dust they pull off the ground. Unlike a tornado, a dust devil typically forms on a clear day when the ground is heated by the sun, warming the air just above the ground. As heated air near the surface rises quickly through a small pocket of cooler air above it, the air may begin to rotate, if conditions are just right. (more…)

Organics Probably Formed Easily in Early Solar System

By Guest PostApril 4, 2012Scienceamino acids, amphiphiles, bombard, building blocks, cellular membrane, cometary, computer simulation, DNA, dynamics, fred ciesla, life on earth, meteorite, nasa ames, nucleobases, organic compound, planet, proteins, rna, science express, scott sandford, solar nebula, uchicago, ultraviolet radiation, uv radiation

Complex organic compounds, including many important to life on Earth, were readily produced under conditions that likely prevailed in the primordial solar system. Scientists at the University of Chicago and NASA Ames Research Center came to this conclusion after linking computer simulations to laboratory experiments.

Fred Ciesla, assistant professor in geophysical sciences at UChicago, simulated the dynamics of the solar nebula, the cloud of gas and dust from which the sun and the planets formed. Although every dust particle within the nebula behaved differently, they all experienced the conditions needed for organics to form over a simulated million-year period. (more…)

Clocking an Accelerating Universe: First Results from BOSS

By Guest PostApril 4, 2012Scienceaccelerate, adam riess, apache point observatory, bao, baryon acoustic oscillation, berkeley lab, beth reid, big bang, brian schmidt, cmb, cosmic microwave background, dan long, dark energy, david schlegel, density peak, einstein, eric huff, euclidean universe, Galaxy, george smoot, gravitational attraction, gravity, high z supernova, hubble, martin white, megaparsecs, Milky Way, new mexico, nobel prize, phenomenon, redshifts, saul perlmutter, scp, sdss, sloan telescope, spectrograph, statistical analysis, universe, zosia rostomian

Berkeley Lab scientists are the leaders of BOSS, the Baryon Oscillation Spectroscopic Survey. They and their colleagues in the third Sloan Digital Sky Survey have announced the most precise measurements ever made of the era when dark energy turned on.

Some six billion light years distant, almost halfway from now back to the big bang, the universe was undergoing an elemental change. Held back until then by the mutual gravitational attraction of all the matter it contained, the universe had been expanding ever more slowly. Then, as matter spread out and its density decreased, dark energy took over and expansion began to accelerate.

Today BOSS, the Baryon Oscillation Spectroscopic Survey, the largest component of the third Sloan Digital Sky Survey (SDSS-III), announced the most accurate measurement yet of the distance scale of the universe during the era when dark energy turned on. (more…)

UCLA Engineering Researchers Use Electricity to Generate Alternative Fuel

By Guest PostApril 3, 2012Sciencecar, carbon dioxide, carbon source, chemical batteries, chemical energy, CO2, co2 fixation, dark reaction, electric vehicle, electrical energy, electricity, electro bioreactor, hydraulic pumping, hydrogen, isobutanol, james liao, liquid fuel, lithoautotrophic microorganism, photosynthesis, ralstonia eutropha h16, solar panels

Imagine being able to use electricity to power your car — even if it’s not an electric vehicle. Researchers at the UCLA Henry Samueli School of Engineering and Applied Science have for the first time demonstrated a method for converting carbon dioxide into liquid fuel isobutanol using electricity.

Today, electrical energy generated by various methods is still difficult to store efficiently. Chemical batteries, hydraulic pumping and water splitting suffer from low energy-density storage or incompatibility with current transportation infrastructure. (more…)

Scientists Find Evidence That Human Ancestors Used Fire One Million Years Ago

By Guest PostApril 3, 2012Scienceanimal bones, ari matmon, boston university, excavation, francesco berna, hagai ron, hebrew university, homo erectus, human ancestors, james brink, kalahari, kimberley, liora kolska horwitz, marion bamford, mcgregor museum, michael chazan, microscopic traces, paul goldberg, peter beaumont, sharon holt, South Africa, stone tools, university of toronto, wonderwerk cave, wood ash

300,000 years earlier than believed

An international team led by the University of Toronto and Hebrew University has identified the earliest known evidence of the use of fire by human ancestors. Microscopic traces of wood ash, alongside animal bones and stone tools, were found in a layer dated to one million years ago at the Wonderwerk Cave in South Africa. (more…)

Rare Animal-Shaped Mounds Discovered in Peru by MU Anthropologist

By Guest PostApril 3, 2012Scienceandres ocas, animal shaped, bernardino ojeda, chan chan, charcoal eye, chillon valley, condor, egypt, google earth, image, june solstice, lucio laura, Milky Way, monstrous caiman, mounds, nazca, North America, ohio, omar ventocilla, peru, peruvian mounds, pyramids, robert benfer, serpent mound, south america, university of missouri

*Anthropology Helps Us Understand the Past and Allows for a Deeper Understanding of the Future.*

COLUMBIA, Mo. — For more than a century and a half, scientists and tourists have visited massive animal-shaped mounds, such as Serpent Mound in Ohio, created by the indigenous people of North America. But few animal effigy mounds had been found in South America until University of Missouri anthropology professor emeritus Robert Benfer identified numerous earthen animals rising above the coastal plains of Peru, a region already renowned for the Nazca lines, the ruined city of Chan Chan, and other cultural treasures.

“The mounds will draw tourists, one day,” Benfer said. “Some of them are more than 4,000 years old. Compare that to the effigy mounds of North America, which date to between 400 and 1200 AD. The oldest Peruvian mounds were being built at the same time as the pyramids in Egypt.” (more…)

Scientists Identify Novel Pathway for T Cell Activation in Leprosy

By Guest PostApril 2, 2012Sciencecell signaling molecule, delphine j lee, dendritic cells, immune cells, infection, interleukin 32, lepromatous leprosy, leprosy, leprosy pathogen, mirjam schenk, monocytes, mycobacteria, mycobacterium leprae, nod2, peter a sieling, protein, robert modlin, skin, stephan r krutzik, t cells, tlr2, tuberloid leprosy, white blood cell

*Findings may help lead to new treatments for infectious diseases, cancer*

UCLA researchers have pinpointed a new mechanism that potently activates T cells, the group of white blood cells that plays a major role in fighting infections.

The team specifically studied how dendritic cells, immune cells located at the site of an infection, become more specialized to fight the leprosy pathogen known as Mycobacterium leprae. Dendritic cells, like scouts in the field of a military operation, deliver key information about an invading pathogen that helps activate the T cells in launching a more effective attack. (more…)

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