Interplay of electronic correlations and lattice instabilities in BaVS3

The quasi-one-dimensional metallic system BaVS3 with a metal-insulator transition at T_MI=70 K shows large changes of the optical phonon spectrum, a central peak, and an electronic Raman scattering continuum that evolve in a three-step process. Motivated by the observation of a strongly fluctuating precursor state at high temperatures and orbital ordering and a charge gap at low temperatures we suggest a concerted action of the orbital, electronic, and lattice subsystems dominated by electronic correlations.Comment: 4 pages, 4 figure

Anomalous frequency and intensity scaling of collective and local modes in a coupled spin tetrahedron system

We report on the magnetic excitation spectrum of the coupled spin tetrahedral system Cu$_{2}$Te$_{2}$O$_{5}$Cl$_{2}$ using Raman scattering on single crystals. The transition to an ordered state at T$_{N}^{Cl}$=18.2 K evidenced from thermodynamic data leads to the evolution of distinct low-energy magnetic excitations superimposed by a broad maximum. These modes are ascribed to magnons with different degree of localization and a two-magnon continuum. Two of the modes develop a substantial energy shift with decreasing temperature similar to the order parameter of other Neel ordered systems. The other two modes show only a negligible temperature dependence and dissolve above the ordering temperature in a continuum of excitations at finite energies. These observations point to a delicate interplay of magnetic inter- and intra-tetrahedra degrees of freedom and an importance of singlet fluctuations in describing a spin dynamics.Comment: 7pages, 6figures, 1tabl

Three-dimensional adaptive evolution of gravitational waves in numerical relativity

Adaptive techniques are crucial for successful numerical modeling of gravitational waves from astrophysical sources such as coalescing compact binaries, since the radiation typically has wavelengths much larger than the scale of the sources. We have carried out an important step toward this goal, the evolution of weak gravitational waves using adaptive mesh refinement in the Einstein equations. The 2-level adaptive simulation is compared with unigrid runs at coarse and fine resolution, and is shown to track closely the features of the fine grid run.Comment: REVTeX, 7 pages, including three figures; submitted to Physical Review

Adaptive mesh refinement approach to construction of initial data for black hole collisions

The initial data for black hole collisions is constructed using a conformal-imaging approach and a new adaptive mesh refinement technique, a fully threaded tree (FTT). We developed a second-order accurate approach to the solution of the constraint equations on a non-uniformly refined high resolution Cartesian mesh including second-order accurate treatment of boundary conditions at the black hole throats. Results of test computations show convergence of the solution as the numerical resolution is increased. FTT-based mesh refinement reduces the required memory and computer time by several orders of magnitude compared to a uniform grid. This opens up the possibility of using Cartesian meshes for very high resolution simulations of black hole collisions.Comment: 13 pages, 11 figure

Different steady states for spin currents in noncollinear multilayers

We find there are at least two different steady states for transport across noncollinear magnetic multilayers. In the conventional one there is a discontinuity in the spin current across the interfaces which has been identified as the source of current induced magnetic reversal; in the one advocated herein the spin torque arises from the spin accumulation transverse to the magnetization of a magnetic layer. These two states have quite different attributes which should be discerned by current experiments.Comment: 8 pages, no figure. Accepted for publication in Journal of Physics: Condensed Matte

Turning to God in the Face of Ostracism: Effects of Social Exclusion on Religiousness

The present research proposes that individuals who are socially excluded can turn to religion to cope with the experience. Empirical studies conducted to test this hypothesis consistently found that socially excluded persons reported (a) significantly higher levels of religious affiliation (Studies 1, 2, and 4) and (b) stronger intentions to engage in religious behaviors (Study 2) than comparable, nonexcluded individuals. Direct support for the stress-buffering function of religiousness was also found, with a religious prime reducing the aggression-eliciting effects of consequent social rejection (Study 5). These effects were observed in both Christian and Muslim samples, revealing that turning to religion can be a powerful coping response when dealing with social rejection. Theoretical and practical implications of these findings are discussed

Spectroscopic Discovery of the Broad-Lined Type Ic Supernova 2010bh Associated with the Low-Redshift GRB 100316D

We present the spectroscopic discovery of a broad-lined Type Ic supernova (SN 2010bh) associated with the nearby long-duration gamma-ray burst (GRB) 100316D. At z = 0.0593, this is the third-nearest GRB-SN. Nightly optical spectra obtained with the Magellan telescopes during the first week after explosion reveal the gradual emergence of very broad spectral features superposed on a blue continuum. The supernova features are typical of broad-lined SNe Ic and are generally consistent with previous supernovae associated with low-redshift GRBs. However, the inferred velocities of SN 2010bh at 21 days after explosion are a factor of ~2 times larger than those of the prototypical SN 1998bw at similar epochs, with v ~ 26,000 km/s, indicating a larger explosion energy or a different ejecta structure. A near-infrared spectrum taken 13.8 days after explosion shows no strong evidence for He I at 1.083 microns, implying that the progenitor was largely stripped of its helium envelope. The host galaxy is of low luminosity (M_R ~ -18.5 mag) and low metallicity (Z < 0.4 Z_solar), similar to the hosts of other low-redshift GRB-SNe.Comment: 6 pages, 4 figures, 1 table, submitted to ApJ Letter

Impact of Clopidogrel Pretreatment on Ischemic Complications of PCI among Bivalirudin-Treated Patients: Results from the EVENT Registry

Computational Infrastructure and Informatics Poster SessionBackground: Although clopidogrel (CLO) pretreatment benefits PCI patients with acute coronary syndromes, these benefits are less well-established among elective PCI patients—particularly when treated with the direct thrombin inhibitor (DTI), bivalirudin. The effect of timing of CLO pretreatment on ischemic complications in these patients is also unknown. Methods: We used data from the multicenter EVENT registry to assess the association of clopidogrel pretreatment (600 mg 2 hr pre-PCI, 300 mg 6 hrs pre-PCI, or 75 mg/d for 1 week) with PCI-related complications in patients undergoing elective PCI with a DTI as planned antithrombotic. The primary endpoint was the composite of in-hospital death or MI (peak CKMB > 3 x ULN). Results: Between 01/05 and 12/07, 3568 pts underwent elective PCI and 1913 (54%) received DTI as planned anticoagulant (37% diabetics, age 65±10 y). Clopidogrel pre-treatment was used in 923 (48%). There were no differences in in-hospital or 1 year ischemic or bleeding events in relation to clopidogrel pretreatment in both unadjusted and adjusted analyses (see Table). There was a trend toward lower rates of death or MI with earlier pretreatment, however [Odds ratios vs. no pretreatment: >1 week 0.48 (95% CI 0.08 - 2.73); > 6 h OR 0.69 (95% CI 0.11 - 4.45) and 2-6 h OR 0.77 (95% CI 0.18 - 3.31)]. Conclusion: Among unselected patients undergoing elective PCI with DTI as the planned anticoagulant, clopidogrel pretreatment was common, but was not associated with a reduced risk of ischemic complications