Tiny drifting animals in the ocean, zooplankton are useful to track oil-derived pollution. They serve as food for baby fish and shrimp and act as conduits for the movement of oil contamination and pollutants into the food chain. The study confirms that not only did oil affect the ecosystem in the Gulf during the blowout, but it was still entering the food web after the well was capped.

Oil, which is a complex mixture of hydrocarbons and other chemicals, contains polycyclic aromatic hydrocarbons (PAHs), which can be used to fingerprint oil and determine its provenance. The researchers were able to identify the signature unique to the Deep Water Horizon well in the Gulf of Mexico.

"Our research helped to determine a 'fingerprint' of the Deepwater Horizon spill -- something that other researchers interested the spill may be able to use," said Dr. Siddhartha Mitra of Eastern Carolina University. "Furthermore, our work demonstrated that zooplankton in the Northern Gulf of Mexico accumulated toxic compounds derived from the Macondo well."

The team's research indicates that the fingerprint of the Deepwater Horizon oil spill could be found in some zooplankton in the Gulf of Mexico ecosystem at low levels, as much as a month after the leaking wellhead was capped. In addition, the extent of the contamination seemed to be patchy. Some zooplankton at certain locations far removed from the spill showed evidence of contamination, whereas zooplankton in other locations, sometimes near the spill, showed lower indications of exposure to the oil-derived pollutants.

"Traces of oil in the zooplankton prove that they had contact with the oil and the likelihood that oil compounds may be working their way up the food chain," said Dr. Michael Roman of the University of Maryland Center for Environmental Science........

"One of the big scientific questions is how did life get started and how did it spread through the universe," said Jay Melosh, distinguished professor of earth and atmospheric sciences. "That question used to be limited to just the Earth, but we now know in our solar system there is a lot of exchange that takes place, and it's quite possible life started on Mars and came to Earth. There's also been a great deal of discussion about the possible spread of life in the universe from star to star."

Moon rocks and Mars meteorites have been found on Earth, which led Melosh to previously suggest living microbes could be exchanged among planets in a similar manner.

A Purdue research team has found that, in contrast to our own solar system, the exchange of living microbes between "super-Earth" and planets in that solar system is not likely to occur.

Laci Brock, a student studying interdisciplinary physics and planetary science, and Melosh will present those findings March 20 at the 43rd Lunar and Planetary Science Conference in The Woodlands, Texas.

Brock examined the Gliese 581 planetary system because Planet d, known as super-Earth, falls in a "habitable zone" where liquid water could possibly exist.

"Laci has found the somewhat surprising result that it is very difficult for materials to spread throughout that system in the same way it could take place in our solar system," Melosh said.

All four planets found in Gliese 581 are within close proximity to their central star, which results in large orbital velocities, Brock said. However, the initial velocity of material leaving Planet d is not enough to allow exchanges among planets.......

His work is published March 23 inScience.

The lithosphere-asthenosphere boundary, or LAB, represents the transition from hot, convecting mantle asthenosphere to overlying cold and rigid lithosphere. The oceanic lithosphere thickens as it cools over time, and eventually sinks back into the mantle at Earth's so-called subduction zones. Studies of seismic waves traveling across the LAB show higher wave speeds in the lithosphere and lower speeds in the asthenosphere. In some regions, seismic waves indicate an abrupt 5 to 10% decrease in wave speeds between 35 and 120 km depth, forming a boundary known as the Gutenberg discontinuity. In many cases, the depth of the Gutenberg discontinuity is roughly coincident with the expected depth of the LAB, leading to the suggestion that the two boundaries are closely inter-related.

However, temperature alone cannot fully explain the abrupt change in the mechanical and seismic properties that have been observed at the Gutenberg discontinuity. This has led many scientists to suggest that other factors--such as the presence of molten rock, water, and/or a decrease in the grain size of minerals--may also play important roles.

Older techniques made imaging seismic discontinuities shallower than 100 kilometers quite difficult, and regions beneath the oceans could only be accessed where seismic stations were installed on ocean islands or by deploying ocean bottom seismometers, giving an incomplete picture of where the Gutenberg occurs beneath the Pacific Ocean.

But an innovative observation technique -- one that incorporates seismic waves that sample beneath remote regions of Earth at higher frequencies, and new signal processing techniques--enabled Schmerr to hone in on the Gutenberg discontinuity.......

The results are reported in the March 23, 2012 issue of the journal Science.

Researchers have known for decades that stimulating various regions of the brain can trigger behaviors and even memories. But understanding the way these brain functions develop and occur normally -- effectively how we become who we are -- has been a much more complex goal.

"The question we're ultimately interested in is: How does the activity of the brain represent the world?" said Scripps Research neuroscientist Mark Mayford, who led the new study. "Understanding all this will help us understand what goes wrong in situations where you have inappropriate perceptions. It can also tell us where the brain changes with learning."

On-Off Switches and a Hybrid Memory

As a first step toward that end, the team set out to manipulate specific memories by inserting two genes into mice. One gene produces receptors that researchers can chemically trigger to activate a neuron. They tied this gene to a natural gene that turns on only in active neurons, such as those involved in a particular memory as it forms, or as the memory is recalled. In other words, this technique allows the researchers to install on-off switches on only the neurons involved in the formation of specific memories.

For the study's main experiment, the team triggered the "on" switch in neurons active as mice were learning about a new environment, Box A, with distinct colors, smells and textures.

Next the team placed the mice in a second distinct environment -- Box B -- after giving them the chemical that would turn on the neurons associated with the memory for Box A. The researchers found the mice behaved as if they were forming a sort of hybrid memory that was part Box A and part Box B. The chemical switch needed to be turned on while the mice were in Box B for them to demonstrate signs of recognition. Alone neither being in Box B nor the chemical switch was effective in producing memory recall.

"We know from studies in both animals and humans that memories are not formed in isolation but are built up over years incorporating previously learned information," Mayford said. "This study suggests that one way the brain performs this feat is to use the activity pattern of nerve cells from old memories and merge this with the activity produced during a new learning session."......

They call the structures periodic bedrock ridges. The ridges look like sand dunes but, rather than being made from material piled up by the wind, the scientists say the ridges actually form from wind erosion of bedrock.

"These bedforms look for all the world like sand dunes but they are carved into hard rock by wind," said David Montgomery, a UW professor of Earth and space sciences. It is something there are not many analogs for on Earth."

He believes the ridges, while still bedrock, are composed of a softer, more erodible material than typical bedrock and were formed by an unusual form of wind erosion that occurs perpendicular to the prevailing wind rather than in the same direction.

He contrasts the ridges with another bedrock form called a yardang, which has been carved over time by headwinds. A yardang has a wide, blunt leading edge in the face of the wind, and its sides are tapered so that it resembles a teardrop.

In the case of periodic bedrock ridges, Montgomery believes high surface winds on Mars are deflected into the air by a land formation, and they erode the bedrock in the area where they settle back to the surface.

Spacing between ridges depends on how long it takes for the winds to come back to the surface, and that is determined by the strength of the wind, the size of the deflection and the density of the atmosphere, he said......

Together with colleagues from Grenoble and Tokyo, Wieck from the Chair of Applied Solid State Physics reports on the results in the journalNature Nanotechnology.

Conventional bits

The basic units of today's data processing are the bit states "0" and "1," which differ in their electrical voltage. To encode these states, only the charge of the electrons is crucial. "Electrons also have other properties though" says Wieck, and these are exactly what you need for quantum bits. "The extension from bits to quantum bits can dramatically increase the computational power of computers" says the physicist.

The new bit generation

A quantum bit corresponds to a single electron in a particular state. Together with his colleagues, Wieck used the trajectories of an electron through two closely spaced channels for encoding. In principle, two different states are possible: the electron either moves in the upper channel or in the lower channel -- which would then only form a binary system again. According to quantum theory, however, a particle can be in several states simultaneously, that is, it can quasi fly through both channels at the same time. These overlapping states can form an extensive alphabet of data processing.

A recipe for qubits

In order to generate quantum bits with different states, the researchers allowed individual electrons to interfere with each other. This works with the so-called Aharonov-Bohm effect: powered by an external voltage, the electrons fly through a semiconducting solid. Within this solid, their trajectory is first forked and then reunited. Thus, each electron flies simultaneously on both possible paths. When the two paths come together again, there is interference, i.e., the two electron waves overlap and quantum bits with different overlapping states are generated.

Controlling electrons on defined paths

Normally, an electron wave moves through a solid body on many different paths at the same time. Due to impurities in the material, it loses its phase information and thus its ability to encode a particular state. To maintain the phase information, the researchers at the RUB grew a high-purity gallium arsenide crystal and used a dual channel proposed by Wieck more than 20 years ago.......

"This is the first experiment where we can directly see local structures in three dimensions at atomic-scale resolution -- that's never been done before," said Jianwei (John) Miao, a professor of physics and astronomy and a researcher with the California NanoSystems Institute (CNSI) at UCLA.

Miao and his colleagues used a scanning transmission electron microscope to sweep a narrow beam of high-energy electrons over a tiny gold particle only 10 nanometers in diameter (almost 1,000 times smaller than a red blood cell). The nanoparticle contained tens of thousands of individual gold atoms, each about a million times smaller than the width of a human hair. These atoms interact with the electrons passing through the sample, casting shadows that hold information about the nanoparticle's interior structure onto a detector below the microscope.

Miao's team discovered that by taking measurements at 69 different angles, they could combine the data gleaned from each individual shadow into a 3-D reconstruction of the interior of the nanoparticle. Using this method, which is known as electron tomography, Miao's team was able to directly see individual atoms and how they were positioned inside the specific gold nanoparticle.

Presently, X-ray crystallography is the primary method for visualizing 3-D molecular structures at atomic resolutions. However, this method involves measuring many nearly identical samples and averaging the results. X-ray crystallography typically takes an average across trillions of molecules, which causes some information to get lost in the process, Miao said.

"It is like averaging together everyone on Earth to get an idea of what a human being looks like -- you completely miss the unique characteristics of each individual," he said.

X-ray crystallography is a powerful technique for revealing the structure of perfect crystals, which are materials with an unbroken honeycomb of perfectly spaced atoms lined up as neatly as books on a shelf. Yet most structures existing in nature are non-crystalline, with structures far less ordered than their crystalline counterparts -- picture a rock concert mosh pit rather than soldiers on parade.......

These results were discussed March 21, 2012 at the Lunar and Planetary Science Conference at The Woodlands, Texas.

Vesta is one of the brightest objects in the solar system and the only asteroid in the so-called main belt between Mars and Jupiter visible to the naked eye from Earth. Dawn has found that some areas on Vesta can be nearly twice as bright as others, revealing clues about the asteroid's history.

"Our analysis finds this bright material originates from Vesta and has undergone little change since the formation of Vesta over 4 billion years ago," said Jian-Yang Li, a Dawn participating scientist at the University of Maryland, College Park. "We're eager to learn more about what minerals make up this material and how the present Vesta surface came to be."

Bright areas appear everywhere on Vesta but are most predominant in and around craters. The areas vary from several hundred feet to around 10 miles (16 kilometers) across. Rocks crashing into the surface of Vesta seem to have exposed and spread this bright material. This impact process may have mixed the bright material with darker surface material.

While scientists had seen some brightness variations in previous images of Vesta from NASA's Hubble Space Telescope, Dawn scientists also did not expect such a wide variety of distinct dark deposits across its surface. The dark materials on Vesta can appear dark gray, brown and red. They sometimes appear as small, well-defined deposits around impact craters. They also can appear as larger regional deposits, like those surrounding the impact craters scientists have nicknamed the "snowman."

"One of the surprises was the dark material is not randomly distributed," said David Williams, a Dawn participating scientist at Arizona State University, Tempe. "This suggests underlying geology determines where it occurs."......