Quantum transport of slow charge carriers in quasicrystals and correlated systems

We show that the semi-classical model of conduction breaks down if the mean free path of charge carriers is smaller than a typical extension of their wavefunction. This situation is realized for sufficiently slow charge carriers and leads to a transition from a metallic like to an insulating like regime when scattering by defects increases. This explains the unconventional conduction properties of quasicrystals and related alloys. The conduction properties of some heavy fermions or polaronic systems, where charge carriers are also slow, present a deep analogy.Comment: 4 page

Predictors and patterns of weight gain during treatment for tuberculosis in the United States of America

SummaryObjectivesPatients with tuberculosis (TB) often present with weight loss. Lack of weight gain with TB treatment has been associated with treatment failure. The purpose of this study was to examine patterns of weight gain in patients with TB and determine the disease characteristics that predict weight gain.MethodsThis was a retrospective cohort study of adults with TB treated in a county health system in the USA. Demographic, clinical, radiographic, and microbiological data were recorded in addition to monthly weights during treatment.ResultsOverall, patients had a significant change in weight over the course of treatment (p<0.0001). After 2 months of treatment, 31.9% of patients had gained at least 5% body weight; by the end of treatment, 62.4% of patients had gained at least 5% weight. Patients who gained weight did so in a linear fashion throughout treatment. Cavitary and extensive disease, a positive smear, and a positive culture were predictors of weight gain (p<0.05). No patients had relapses during the time period of the study.ConclusionsOnly a subset of patients treated for TB gain significant weight. A greater burden of disease was predictive of weight gain

Synthesis and characterization of thorium-bearing britholites

RADIOCHIn the field of the immobilization of tri- and tetravalent minor actinides, apatites and especially britholites were already proposed as good candidates. In order to simulate tetravalent minor actinides, the incorporation of thorium, through dry chemical routes, was studied in britholite samples of general formula Ca9Nd1−xThx(PO4)5−x(SiO4)1+xF2. The study showed that the incorporation of thorium was effective whatever the thorium reagent used or the grinding conditions considered. Nevertheless, it appeared necessary to use mechanical grinding (30 Hz, 15 min) before heating treatment (T = 1400 °C, 6 h) to improve the reactivity of powders and the sample homogeneity. In these conditions, the incorporation of thorium in the britholite structure occurred above 1100 °C. The heating treatment at 1400 °C led to single phase and homogeneous compounds. This work also underlined the necessity to prefer the coupled substitution Click to view the MathML source instead of (Nd3+, F−) left right double arrow (Th4+, O2−) in order to prepare pure and single phase samples in all the range of composition examined

Two superluminous supernovae from the early universe discovered by the Supernova Legacy Survey

We present spectra and lightcurves of SNLS 06D4eu and SNLS 07D2bv, two hydrogen-free superluminous supernovae discovered by the Supernova Legacy Survey. At z = 1.588, SNLS 06D4eu is the highest redshift superluminous SN with a spectrum, at M_U = -22.7 is one of the most luminous SNe ever observed, and gives a rare glimpse into the restframe ultraviolet where these supernovae put out their peak energy. SNLS 07D2bv does not have a host galaxy redshift, but based on the supernova spectrum, we estimate it to be at z ~ 1.5. Both supernovae have similar observer-frame griz lightcurves, which map to restframe lightcurves in the U-band and UV, rising in ~ 20 restframe days or longer, and declining over a similar timescale. The lightcurves peak in the shortest wavelengths first, consistent with an expanding blackbody starting near 15,000 K and steadily declining in temperature. We compare the spectra to theoretical models, and identify lines of C II, C III, Fe III, and Mg II in the spectrum of SNLS 06D4eu and SCP 06F6, and find that they are consistent with an expanding explosion of only a few solar masses of carbon, oxygen, and other trace metals. Thus the progenitors appear to be related to those suspected for SNe Ic. A high kinetic energy, 10^52 ergs, is also favored. Normal mechanisms of powering core- collapse or thermonuclear supernovae do not seem to work for these supernovae. We consider models powered by 56Ni decay and interaction with circumstellar material, but find that the creation and spin-down of a magnetar with a period of 2ms, magnetic field of 2 x 10^14 Gauss, and a 3 solar mass progenitor provides the best fit to the data.Comment: ApJ, accepted, 43 pages, 15 figure

An Efficient Approach to Obtaining Large Numbers of Distant Supernova Host Galaxy Redshifts

We use the wide-field capabilities of the 2dF fibre positioner and the AAOmega spectrograph on the Anglo-Australian Telescope (AAT) to obtain redshifts of galaxies that hosted supernovae during the first three years of the Supernova Legacy Survey (SNLS). With exposure times ranging from 10 to 60 ksec per galaxy, we were able to obtain redshifts for 400 host galaxies in two SNLS fields, thereby substantially increasing the total number of SNLS supernovae with host galaxy redshifts. The median redshift of the galaxies in our sample that hosted photometrically classified Type Ia supernovae (SNe Ia) is 0.77, which is 25% higher than the median redshift of spectroscopically confirmed SNe Ia in the three-year sample of the SNLS. Our results demonstrate that one can use wide-field fibre-fed multi-object spectrographs on 4m telescopes to efficiently obtain redshifts for large numbers of supernova host galaxies over the large areas of sky that will be covered by future high-redshift supernova surveys, such as the Dark Energy Survey.Comment: 22 pages, 4 figures, accepted for publication in PAS

Design guide for high pressure oxygen systems

A repository for critical and important detailed design data and information, hitherto unpublished, along with significant data on oxygen reactivity phenomena with metallic and nonmetallic materials in moderate to very high pressure environments is documented. This data and information provide a ready and easy to use reference for the guidance of designers of propulsion, power, and life support systems for use in space flight. The document is also applicable to designs for industrial and civilian uses of high pressure oxygen systems. The information presented herein are derived from data and design practices involving oxygen usage at pressures ranging from about 20 psia to 8000 psia equal with thermal conditions ranging from room temperatures up to 500 F

Seismic Risk Analysis for a Site Along the Gorda Segment of the Cascadia Subduction Zone

A seismic risk evaluation was conducted on a site near Eureka, California. The site was subject to potential earthquake loading from a number of sources. These sources were: (1) Mendocino Fracture Zone, (2) Gorda Segment of the Cascadia Subduction Zone, (3) Little Salmon thrust fault under the site, (4) Mad River Fault Zone, and (5) Intra plate west - Gorda Plate. The geology of thrust faults in Northern California is examined along with that of the Mendocino Fracture Zone, and the southern section (Gorda Segment) of the Cascadia subduction zone. A trench log showing a splay of the Little Salmon Fault is presented. A seismic risk analysis of the site was performed using recurrence curves for the various seismic sources estimated from both trench studies and historic seismicity. Using this information the acceleration at the site due to the Maximum Credible Earthquake is estimated to be 0.85g. The corresponding acceleration due to the Maximum Probable Earthquake and assuming that the various fault zones act independently or co-seismically is estimated to be 0.5g

Expansion of the ligand knowledge base for chelating P,P-donor ligands (LKB-PP)

[Image: see text] We have expanded the ligand knowledge base for bidentate P,P- and P,N-donor ligands (LKB-PP, Organometallics2008, 27, 1372–1383) by 208 ligands and introduced an additional steric descriptor (nHe(8)). This expanded knowledge base now captures information on 334 bidentate ligands and has been processed with principal component analysis (PCA) of the descriptors to produce a detailed map of bidentate ligand space, which better captures ligand variation and has been used for the analysis of ligand properties