3,972 research outputs found

    The Effects of Rumination Induction on Attentional Breadth for Self-Related Information

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    The attentional scope model of rumination describes the links between rumination and attentional breadth. The model postulates that a more narrow attentional scope, caused by negative mood, increases the likelihood that thoughts become repetitive on the same topic, which in turn could exacerbate negative mood and lead to more attentional narrowing. We experimentally tested this model by examining the attentional effects of rumination using a newly developed rumination- versus problem-solving induction. In the first experiment we found that only at high levels of trait rumination, induction of rumination compared to a problem-solving approach was associated with more attentional narrowing for self-related information relative to other-related information. A second experiment on the relationship between trait rumination and attentional breadth in the absence of induced rumination, revealed that especially trait brooding was related to more narrowed attention for self-related information relative to other-related information

    Electronic and phononic properties of cinnabar: ab initio calculations and some experimental results

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    We report ab initio calculations of the electronic band structure, the corresponding optical spectra, and the phonon dispersion relations of trigonal alpha-HgS (cinnabar). The calculated dielectric functions are compared with unpublished optical measurements by Zallen and coworkers. The phonon dispersion relations are used to calculate the temperature and isotopic mass dependence of the specific heat which has been compared with experimental data obtained on samples with the natural isotope abundances of the elements Hg and S (natural minerals and vapor phase grown samples) and on samples prepared from isotope enriched elements by vapor phase transport. Comparison of the calculated vibrational frequencies with Raman and ir data is also presented. Contrary to the case of cubic beta-HgS (metacinnabar), the spin-orbit splitting of the top valence bands at the Gamma-point of the Brillouin zone (Delta_0) is positive, because of a smaller admixture of 5d core electrons of Hg. Calculations of the lattice parameters, and the pressure dependence of Delta_0 and the corresponding direct gap E_0~2eV are also presented. The lowest absorption edge is confirmed to be indirect.Comment: 13 pages, 15 figure

    Robust optical emission polarization in MoS2 monolayers through selective valley excitation

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    We report polarization resolved photoluminescence from monolayer MoS2, a two-dimensional, non-centrosymmetric crystal with direct energy gaps at two different valleys in momentum space. The inherent chiral optical selectivity allows exciting one of these valleys and close to 90% polarized emission at 4K is observed with 40% polarization remaining at 300K. The high polarization degree of the emission remains unchanged in transverse magnetic fields up to 9T indicating robust, selective valley excitation.Comment: 5 pages, 3 figure

    Gene Expression Profiling in a Mouse Model Identifies Fetal Liver- and Placenta-Derived Potential Biomarkers for Down Syndrome Screening

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    BACKGROUND: As a first step to identify novel potential biomarkers for prenatal Down Syndrome screening, we analyzed gene expression in embryos of wild type mice and the Down Syndrome model Ts1Cje. Since current Down Syndrome screening markers are derived from placenta and fetal liver, these tissues were chosen as target. METHODOLOGY/PRINCIPAL FINDINGS: Placenta and fetal liver at 15.5 days gestation were analyzed by microarray profiling. We confirmed increased expression of genes located at the trisomic chromosomal region. Overall, between the two genotypes more differentially expressed genes were found in fetal liver than in placenta. Furthermore, the fetal liver data are in line with the hematological aberrations found in humans with Down Syndrome as well as Ts1Cje mice. Together, we found 25 targets that are predicted (by Gene Ontology, UniProt, or the Human Plasma Proteome project) to be detectable in human serum. CONCLUSIONS/SIGNIFICANCE: Fetal liver might harbor more promising targets for Down Syndrome screening studies. We expect these new targets will help focus further experimental studies on identifying and validating human maternal serum biomarkers for Down Syndrome screening

    Point symmetries in the Hartree-Fock approach: Symmetry-breaking schemes

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    We analyze breaking of symmetries that belong to the double point group D2h(TD) (three mutually perpendicular symmetry axes of the second order, inversion, and time reversal). Subgroup structure of the D2h(TD) group indicates that there can be as much as 28 physically different, broken-symmetry mean-field schemes --- starting with solutions obeying all the symmetries of the D2h(TD) group, through 26 generic schemes in which only a non-trivial subgroup of D2h(TD) is conserved, down to solutions that break all of the D2h(TD) symmetries. Choices of single-particle bases and the corresponding structures of single-particle hermitian operators are discussed for several subgroups of D2h(TD).Comment: 10 RevTeX pages, companion paper in nucl-th/991207

    Local Electronic Structure of a Single Magnetic Impurity in a Superconductor

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    The electronic structure near a single classical magnetic impurity in a superconductor is determined using a fully self-consistent Koster-Slater algorithm. Localized excited states are found within the energy gap which are half electron and half hole. Within a jellium model we find the new result that the spatial structure of the positive-frequency (electron-like) spectral weight (or local density of states), can differ strongly from that of the negative frequency (hole-like) spectral weight. The effect of the impurity on the continuum states above the energy gap is calculated with good spectral resolution for the first time. This is also the first three-dimensional self-consistent calculation for a strong magnetic impurity potential.Comment: 13 pages, RevTex, change in heuristic picture, no change in numerical result

    A Microscopic T-Violating Optical Potential: Implications for Neutron-Transmission Experiments

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    We derive a T-violating P-conserving optical potential for neutron-nucleus scattering, starting from a uniquely determined two-body ρ\rho-exchange interaction with the same symmetry. We then obtain limits on the T-violating ρ\rho-nucleon coupling gρ\overline{g}_{\rho} from neutron-transmission experiments in 165^{165}Ho. The limits may soon compete with those from measurements of atomic electric-dipole moments.Comment: 8 pages, 2 uuencoded figures in separate files (replaces version sent earlier in the day with figures attached), in RevTeX 3, submitted to PR
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