Washington, D.C.—Chemical compounds called manganites have been studied for many years since the discovery of colossal magnetoresistance, a property that promises important applications in the fields of magnetic sensors, magnetic random access memories and spintronic devices. However, understanding—and ultimately controlling—this effect remains a challenge, because much about manganite physics is still not known.
Earth
A milestone in the international Avogadro project coordinated by the Physikalisch-Technische Bundesanstalt (PTB) has been reached: With the aid of a single crystal of highly enriched 28Si, the Avogadro constant has now been measured as exactly as never before with a relative overall uncertainty of 3 · 10-8. Within the scope of the redefinition of the kilogram, the value NA = 6.02214078(18) · 1023 mol-1 permits the currently most exact realization of this unit. The results have been published in the most recent edition of the journal "Physical Review Letters".
Millbrook, NY— If society wants to address big picture environmental problems, like global climate change, acid rain, and coastal dead zones, we need to pay closer attention to the Earth's coupled biogeochemical cycles. So reports a special issue of Frontiers in Ecology and the Environment, published this month by the Ecological Society of America.
COLUMBIA, Mo. – This December marks the bicentennial of the New Madrid earthquakes of 1811-12, which are the biggest earthquakes known to have occurred in the central U.S.
Now, based on the earthquake record in China, a University of Missouri researcher says that mid-continent earthquakes tend to move among fault systems, so the next big earthquake in the central U.S. may actually occur someplace else other than along the New Madrid faults.
A study of bound protons and neutrons conducted at the Department of Energy's Thomas Jefferson National Accelerator Facility has allowed scientists, for the first time, to extract information through experimentation about the internal structure of free neutrons, without the assistance of a theoretical model. The result was published in the Feb. 4 issue of Physical Review Letters.
OAK RIDGE, Tenn. Feb. 7, 2011 -- Neutron scattering analysis of two families of iron-based materials suggests that the magnetic interactions thought responsible for high-temperature superconductivity may lie "two doors down": The key magnetic exchange pairings occur in a next-nearest-neighbor ordering of atoms, rather than adjacent atoms.
Elements heavier than iron come into being only in powerful stellar explosions, supernovae. During nuclear reactions all kinds of short-lived atomic nuclei are formed, including more stable combinations – the so-called magic numbers – predicted by theory. Yet here, too, there are exceptions: the islands of inversion. Headed by physicists from the Excellence Cluster Universe at the Technische Universitaet Muenchen (TUM), an international team of scientists has now taken a closer look at the island that was first discovered.
Nacre, commonly known as mother-of-pearl, is the iridescent material lining many mollusk shells. It is part of a two-layer armor system that protects the animal from predators. The brittle outer layer of the shell absorbs the initial impact, but is prone to cracking. To prevent these cracks from catastrophically propagating through the shell to the animal itself, the nacreous layer is surprisingly strong and tough, with outstanding crack arresting properties. Thus it acts as a lining to maintain the integrity of the shell in the event of cracking of the outer layer.
Faulted terrace risers place new constraints on the late Quaternary slip rate for the central Altyn Tagh fault, northwest TibetRyan D. Gold et al., Dept. of Geology, University of California, Davis, California 95616, USA. Published online 28 Jan. 2011; doi: 10.1130/B30207.1.
BOULDER, Colo.—In a paradox typical of the quantum world, JILA scientists have eliminated collisions between atoms in an atomic clock by packing the atoms closer together. The surprising discovery, described in the Feb. 3 issue of Science Express,* canboost the performance of experimental atomic clocks made of thousands or tens of thousands of neutral atoms trapped by intersecting laser beams.
JILA is jointly operated by the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder.
A new way of splitting layered materials to give atom thin "nanosheets" has been discovered. This has led to a range of novel two-dimensional nanomaterials with chemical and electronic properties that have the potential to enable new electronic and energy storage technologies. The collaborative* international research led by the Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Ireland, and the University of Oxford has been published in this week's Science.
One of the most significant socioeconomic changes in the history of humanity took place around 10,000 years ago, when the Near East went from an economy based on hunting and gathering (Mesolithic) to another kind on agriculture (Neolithic). Farmers rapidly entered the Balkan Peninsula and then advanced gradually throughout the rest of Europe.
New experiments show that common scientific rules can apply to significantly different phenomena operating on vastly different scales.
The results raise the possibility of making discoveries pertaining to phenomena that would be too large or impractical to recreate in the laboratory, said Cheng Chin, associate professor in physics and the James Franck Institute at the University of Chicago. Chin and associates Chen-Lung Hung, Xibo Zhang and Nathan Gemelke published their results in the Jan. 26 Advance Online Publication (Feb. 10 print edition) of the journal Nature.
RENO, Nev. – A team of University of Nevada, Reno and University of Nevada, Las Vegas researchers have devised a new model for how Nevada's gold deposits formed, which may help in exploration efforts for new gold deposits.