Replication Protein A (RPA) is the primary eukaryotic ssDNA binding protein utilized in diverse DNA transactions in the cell. RPA is a heterotrimeric protein with seven globular domains connected by flexible linkers, which enable substantial inter-domain motion that is essential to its function. Small angle X-ray scattering (SAXS) experiments on two multi-domain constructs from the N-terminus of the large subunit (RPA70) were used to examine the structural dynamics of these domains and their response to the binding of ssDNA. The SAXS data combined with molecular dynamics simulations reveal substantial interdomain flexibility for both RPA70AB (the tandem high affinity ssDNA binding domains A and B connected by a 10-residue linker) and RPA70NAB (RPA70AB extended by a 70-residue linker to the RPA70N protein interaction domain). Binding of ssDNA to RPA70NAB reduces the interdomain flexibility between the A and B domains, but has no effect on RPA70N. These studies provide the first direct measurements of changes in orientation of these three RPA domains upon binding ssDNA. The results support a model in which RPA70N remains structurally independent of RPA70AB in the DNA bound state and therefore freely available to serve as a protein recruitment module.

X-ray absorption spectra of 1M aqueous solutions of indium (III) chloride, yttrium (III) bromide, lanthanum (III) chloride, tin (IV) chloride and chromium (III) chloride have been measured at the oxygen K-edge. Relatively minor changes are observed in the spectra compared to that of pure water. SnCl{sub 4} and CrCl{sub 3} exhibit a new onset feature which is attributed to formation of hydroxide or other complex molecules in the solution. At higher energy, only relatively minor, but salt-specific changes in the spectra occur. The small magnitude of the observed spectral changes is ascribed to offsetting perturbations by the cations and anions.

Vacuum ultraviolet photoionization coupled to secondary neutral mass spectrometry (VUV-SNMS) of deposited tryptophan and thymine films are performed at the Chemical Dynamics Beamline. The resulting mass spectra show that while the intensity of the VUV-SNMS signal is lower than the corresponding secondary ion mass spectroscopy (SIMS) signal, the mass spectra are significantly simplified in VUV-SNMS. A detailed examination of tryptophan and thymine neutral molecules sputtered by 25 keV Bi3 + indicates that the ion-sputtered parent molecules have ~;;2.5 eV of internal energy. While this internal energy shifts the appearance energy of the photofragment ions for both tryptophan and thymine, it does not change the characteristic photoionizaton efficiency (PIE) curves of thymine versus photon energy. Further analysis of the mass spectral signals indicate that approximately 80 neutral thymine molecules and 400 tryptophan molecules are sputtered per incident Bi3 + ion. The simplified mass spectra and significant characteristic ion contributions to the VUV-SNMS spectra indicate the potential power of the technique for organic molecule surface analysis.

Concern over the quality of environmental management and restoration has motivated the model development for predicting water and solute transport in the vadose zone. Soil hydraulic properties are required inputs to subsurface models of water flow and contaminant transport in the vadose zone. Computer models are now routinely used in research and management to predict the movement of water and solutes into and through the vadose zone of soils. Such models can be used successfully only if reliable estimates of the soil hydraulic parameters are available. The hydraulic parameters considered in this project consist of the saturated hydraulic conductivity and four parameters of the water retention curves. To quantify hydraulic parameters for heterogeneous soils is both difficult and time consuming. The overall objective of this project was to better quantify soil hydraulic parameters which are critical in predicting water flows and contaminant transport in the vadose zone through a comprehensive and quantitative study to predict heterogeneous soil hydraulic properties and the associated uncertainties. Systematic and quantitative consideration of the parametric heterogeneity and uncertainty can properly address and further reduce predictive uncertainty for contamination characterization and environmental restoration at DOE-managed sites. We conducted a comprehensive study to assess soil hydraulic parameter …

Integrating the Molecular Machines of Mercury Detoxification into Host Cell Biology The bacterial mercury resistance (mer) operon, one of the most evolutionarily successful genetic loci in any defined organism, detoxifies organic and inorganic mercury compounds. Several major biotic processes in the global Hg(II) cycle are carried out by bacteria with this highly mobile detoxification locus that occurs in Gram negative and high and low GC Gram positive bacteria. The functions of many individual mer operon components are well described, so we aim to dissect the higher order interactions of the enzymes, transporters, and regulators of this paradigm metal metabolizing system with each other and with the larger metabolism of the host cell. Understanding how this ubiquitous detoxification system fits into the biology and ecology of its bacterial host is essential to guide interventions that support and enhance Hg remediation. Specifically, we will test the hypotheses that: (a) the organomercurial lyase, MerB, and the mercuric reductase, MerA, act synergistically together and with the membrane-bound Hg(II) transporters, MerT and MerC, to detoxify mercurials; (b) the interaction of the metalloregulator MerR with RNA polymerase (RNAP) and with its DNA binding site, MerO, modulates its metal response, and interaction with its antagonist, MerD, prevents …

The time-temperature-transformation (TTT) curve for the {delta} {yields} {alpha}{prime} isothermal martensitic transformation in a Pu-1.9 at. % Ga alloy is peculiar because it is reported to have a double-C curve. Recent work suggests that an ambient temperature conditioning treatment enables the lower-C curve. However, the mechanisms responsible for the double-C are still not fully understood. When the {delta} {yields} {alpha}{prime} transformation is induced by pressure, an intermediate {gamma}{prime} phase is observed in some alloys. It has been suggested that transformation at upper-C temperatures may proceed via this intermediate phase, while lower-C transformation progresses directly from {delta} to {alpha}{prime}. To investigate the possibility of thermally induced transformation via the intermediate {gamma}{prime} phase, in situ x-ray diffraction at the Advanced Photon Source was performed. Using transmission x-ray diffraction, the {delta} {yields} {alpha}{prime} transformation was observed in samples as thin at 30 {micro}m as a function of time and temperature. The intermediate {gamma}{prime} phase was not observed at -120 C (upper-C curve) or -155 C (lower-C curve). Results indicate that the bulk of the {alpha}{prime} phase forms relatively rapidly at -120 C and -155 C.

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Using x-ray computerized tomography (CT), we have characterized the x-ray linear attenuation coefficients (LAC) of a Play Dough{trademark}-like product, Fun Dough{trademark}, designated as PD. Table 1 gives the first-order statistics for each of four CT measurements, estimated with a Gaussian kernel density estimator (KDE) analysis. The mean values of the LAC range from a high of about 2100 LMHU{sub D} at 100kVp to a low of about 1100 LMHU{sub D} at 300kVp. The standard deviation of each measurement is around 1% of the mean. The entropy covers the range from 3.9 to 4.6. Ordinarily, we would model the LAC of the material and compare the modeled values to the measured values. In this case, however, we did not have the composition of the material and therefore did not model the LAC. Using a method recently proposed by Lawrence Livermore National Laboratory (LLNL), we estimate the value of the effective atomic number, Z{sub eff}, to be near 8.5. LLNL prepared about 50mL of the Fun Dough{trademark} in a polypropylene vial and firmly compressed it immediately prior to the x-ray measurements. Still, layers can plainly be seen in the reconstructed images, indicating that the bulk density of the material in the container …

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This report is categorized into six categories: (I) Introduction, (II) FOIA History, (III) The George W. Bush Administration, (IV) 110TH Congress Legislative Reform Efforts, (V) The Obama Administration, and (VI) FOIA and the 111th Congress.

This report discusses the banking collapse in Iceland. Iceland's banking system had collapsed as a result of a culmination of a series of decisions the banks made that left them highly exposed to disruptions in financial markets. The collapse of the banks raised questions for U.S. leaders and others about supervising banks that operate across national borders, especially as it has become increasingly difficult to distinguish the limits of domestic financial markets.

This report provides information and analysis on Moldova, including its political and economic situation, foreign policy, and on U.S. policy toward Moldova.

This report discusses the idea that all Americans should be able to afford access to the telecommunications network; this is commonly called the "universal service concept" and can trace its origins back to the 1934 Communications Act.

This report focuses on how major developed and emerging-market country governments, particularly the G-20 and Organization for Economic Cooperation and Development (OECD) countries, limit their fiscal deficits.

This report discusses the internal and external security concerns of the South Caucasus states and U.S. interests and policy toward the region. The countries of Armenia, Azerbaijan, and Georgia are generally considered as comprising the South Caucasus region, which borders Russia, Turkey, and Iran.

his report explores the significance and state of U.S.-Japan economic ties; how the ties have changed over time; and what the possible options for managing the relationship might be.

This report discusses the Earthquake in Chile, the current condition, the response from Chilean government, international humanitarian response, as well as the U.S. humanitarian response. The report provides background information on Chile and U.S. relations and policy issues.

This report examines the major features of economic models being used to estimate the effects of trade agreements. It assesses the strengths and weaknesses of the models as an aid in helping Congress evaluate the economic impact of trade agreements on the U.S. economy.

This report discusses the internal and external security concerns of the Central Asian states. Security concerns faced by the states include mixes of social disorder, crime, corruption, terrorism, ethnic and civil conflict, border tensions, water and transport disputes, the proliferation of weapons of mass destruction (WMD), and trafficking in illegal narcotics and persons.

This report provides overview information on the proposed FY2011 budget request for the Department of Homeland Security (DHS) programs that provide assistance to state and local governments. These programs are primarily used by first responders -- including firefighters, emergency medical personnel, emergency managers, and law enforcement officers -- to provide assistance for training, exercises, the purchase of equipment, and other support for terrorism and disaster preparedness and response activities.

This report discusses the reasons that Iran is considered a threat to U.S. security, including Iran's nuclear program, involvement with terrorist organizations, and involvement with neighboring countries' local governments. The report also discusses ways which the U.S. hopes to modify Iran's behavior with sanctions, and the effectiveness of these sanctions.

This report examines the Organization for Economic Cooperation and Development (OECD) and its role in changes to U.S. laws related to bribery, tax havens.