Insights into Hydration Dynamics and Cooperative Interactions in Glycerol-Water Mixtures by Terahertz Dielectric Spectroscopy.

We report relaxation dynamics of glycerol-water mixtures as probed by megahertz-to-terahertz dielectric spectroscopy in a frequency range from 50 MHz to 0.5 THz at room temperature. The dielectric relaxation spectra reveal several polarization processes at the molecular level with different time constants and dielectric strengths, providing an understanding of the hydrogen-bonding network in glycerol-water mixtures. We have determined the structure of hydration shells around glycerol molecules and the dynamics of bound water as a function of glycerol concentration in solutions using the Debye relaxation model. The experimental results show the existence of a critical glycerol concentration of ∼7.5 mol %, which is related to the number of water molecules in the hydration layer around a glycerol molecule. At higher glycerol concentrations, water molecules dispersed in a glycerol network become abundant and eventually dominate, and four distinct relaxation processes emerge in the mixtures. The relaxation dynamics and hydration structure in glycerol-water mixtures are further probed with molecular dynamics simulations, which confirm the physical picture revealed by the dielectric spectroscopy

All-Optical Electron Injector

Conventional electron acceleration at a place like SLAC needs miles to boost particles up to 50 GeV energies by feeding them microwaves in a succession of special cavities. In recent years physicists have been developing alternative acceleration concepts that might someday do the job in a much smaller space. Their near-term goal is to produce a first stage accelerator that outputs electron beams with lower energy but with properties that are more suitable for x-ray sources, such as those based on Compton scattering or the proposed linear synchrotrons at SLAC and DESY

CMap 1.01: a comparative mapping application for the Internet

Summary:CMap is a web-based tool for displaying and comparing maps of any type and from any species. A user can compare an unlimited number of maps, view pair-wise comparisons of known correspondences, and search for maps or for features by name, species, type and accession. CMap is freely available, can run on a variety of database engines and uses only free and open software components

Field Programmable Reconfigurable Mesh (FPRM)

Many application areas demand increasing amounts of processing capabilities. FPGAs have been widely used for improving this performance. FPRM (Field Programmable Reconfigurable Mesh) is a technique we propose to improve FPGA performance. A Reconfigurable Mesh (RM) consists of a grid of Processing Elements that use dynamic reconfigurations to create varying bus segments between them. The RM can thus perform computations such as Sorting or Counting in a constant number of steps. It has long been speculated that the RM’s dynamic reconfigurations should replace the FPGA’s static reconfigurations. We show that the RM is capable of not only speeding up specific computations such as sorting or summing, but also of speeding up the evaluation of Boolean circuits (BCs), which is the main purpose of the FPGA. Our proposed RM algorithm can evaluate BCs without causing size blowup. Furthermore, tri-state switching elements can be used instead of PEs in a grid

Relationships of Perfluorooctanoate and Perfluorooctane Sulfonate Serum Concentrations between Mother–Child Pairs in a Population with Perfluorooctanoate Exposure from Drinking Water

Background: There are limited data on the associations between maternal or newborn and child exposure to perfluoroalkyl acids (PFAAs), including perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS). This study provides an opportunity to assess the association between PFAA concentrations in mother–child pairs in a population exposed to PFOA via drinking water