Assessing the efficiency of first-principles basin-hopping sampling

We present a systematic performance analysis of first-principles basin-hopping (BH) runs, with the target to identify all low-energy isomers of small Si and Cu clusters described within density-functional theory. As representative and widely employed move classes we focus on single-particle and collective moves, in which one or all atoms in the cluster at once are displaced in a random direction by some prescribed move distance, respectively. The analysis provides detailed insights into the bottlenecks and governing factors for the sampling efficiency, as well as simple rules-of-thumb for near-optimum move settings, that are intriguingly independent of the distinctly different chemistry of Si and Cu. At corresponding settings, the observed performance of the BH algorithm employing two simple, general-purpose move classes is already very good, and for the small systems studied essentially limited by frequent revisits to a few dominant isomers.Comment: 11 pages including 8 figures; related publications can be found at http://www.fhi-berlin.mpg.de/th/th.htm

Gas-liquid chromatography of amino acids in biological substances

Developing gas-liquid chromatographic method for quantitative analysis of amino acids in blood plasma and urin

An Analysis of the Impact of European Union and United States Dairy Policies on EU-U.S. Trade in Milk Protein Concentrate

During 1996-2000, U.S. imports of milk protein concentrate (MPC) increased rapidly. At the same time, Commodity Credit Corporation (CCC) stocks of non-fat dry milk (NFDM) went from nothing to more than 500 million pounds. Consequently, U.S. milk producers attributed low milk prices and dairy farmer income during this period to the increased imports of MPC. U.S. milk producers were especially concerned with MPC imports for two reasons. First, MPC between 40 and 90 percent protein had been classified in subheading 0404.90.10 of the Harmonized Tariff Schedule of the United States (HTS). Thus, MPC was not subject to the tariff-rate quotas applied to many other dairy products. Second, MPC produced in the European Union (EU) and exported to the United States was eligible for production and export subsidies. Along with the high U.S. internal milk protein prices maintained by the Dairy Price Support Program, and volatile world prices of NFDM, these policies created economic rents for trade in MPC between the European Union and the United States. To test the relationship between these policies and U.S. imports of MPC, these economic rents, which were not directly observable, were estimated by combing a set of identifiable variables: (1) the CCC purchase price, (2) the EU export refund, (3) EU casein production aid, and (4) the world price of NFDM as expressed by the Western Europe export price. A vector autoregression model was then estimated using monthly U.S. imports of MPC and the estimate of economic rents. This estimation showed that nearly 40 percent of the variability in U.S. MPC imports was attributable to the estimate of economic rents. These results demonstrate that U.S. and EU policies can not be analyzed in isolation when evaluating the impact of dairy policies on U.S. MPC imports.Agricultural and Food Policy, International Relations/Trade,

Hiding Private Locations by Anonymizing Data

Researchers explore ways of masking private locations in the interest of making useful data publicly available

How access to public transit may have saved many Americans’ homes during the Great Recession

The Great Recession which followed the 2008 financial crash saw massive increases in the number of homes being foreclosed and trillions wiped from homeowners’ equity. But the impact of the recession was not uniform across the country in all places. In new research, Timothy F. Welch, Steven R. Gehrke and Steven Farber look at the effects of access to public transport on house prices during the Great Recession. They find that houses less than a mile from stations in Atlanta, Baltimore or Portland all kept their value to a greater degree than those located farther away from stations.They suggest that this may be down to lower transport-related costs, better local economic conditions and greater access to employment opportunities

Plan for the testing of radiation measurement instrumentation intended for use at an excavation site

This plan describes performance tests to be made with ionizing radiation measurement instrumentation designed and built for in-field assay at an excavation site. One instrument measures gross gamma-ray and neutron fields and the other identifies gamma-ray emitting radionuclides and also is capable of assaying for selected hazardous materials. These instruments will be operationally tested to verify that original specifications have been met and performance tested to establish and verify that they have the potential to function as intended at an excavation site

2,2′-[(E,E)-cis-(Cyclo­hexane-1,4-di­yl)bis­(nitrilo­methanylyl­idene)]diphenol

In the title compound, C20H22N2O2, the asymmetric unit contains two independent half-mol­ecules, which are both completed by crystallographic inversion symmetry. The cyclo­hexane rings of both mol­ecules adopt chair conformations; the N atoms are in equatorial orientations in one mol­ecule and in axial orientations in the other. Both mol­ecules feature two intra­molecular O—H⋯N hydrogen bonds, which generate S(6) rings