184 research outputs found

    Noticing the self: Implicit assessment of self-focused attention using word recognition latencies

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    Self-focused attention is difficult to measure. Two studies developed an implicit measure of self-focus based on word recognition latencies. Self-focused attention activates self-content, so self-focused people should recognize self-relevant words more quickly. Study 1 measured individual-differences in self-focused attention. People scoring high in private self-consciousness recognized self-relevant words more quickly. Study 2 manipulated objective self-awareness with a writing task. People who wrote about distinctive self-aspects (high self-awareness) recognized self-relevant words more quickly compared to people who wrote about a neutral topic (low self-awareness) and people who did no writing (control). The discussion considers implications for future research on self-focused attention

    Studying Electron Dynamics for Quantum Materials with Real Space Resolution: A Wannier Orbital Approach to Spectroscopy using High-Performance Supercomputers

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    Quantum materials have a promising future for energy and security applications which will lay the bedrock for material science research for decades to follow. Partic- ularly, ‘one-dimensional’ Mott-insulating cuprates such as SrCuO 2 and (Ca)Sr 2 CuO 3 have been deemed to fall under a ‘fractionalization’ paradigm in which the electrons disintegrate into bosonic collective excitations of their fundamental constituents— spin, charge, and ‘orbital’ degrees of freedom— due to the anisotropic crystalline structure, deeming them outside the band theory of solids. Here, I provide ab initio theory for the ‘one-dimensional’ cuprates SrCuO 2 and (Ca)Sr 2 CuO 3 using no adjustable parameters with excellent agreement in absolute units with optical conductivity, dielectric function, and loss function measurements. In addition, we i) notice an overlooked ‘discontinuity’ in the loss dispersion at the antiferromagnetic zone boundary and provide theory to fill this void; ii) predict a novel Mott-gapped longitudinal spin excitation that can be verified via inelastic neutron scattering measurements; and iii) predict a re-emergence of the charge density excitations in higher Brillouin zones which can be validated with non-resonant inelastic X-ray scattering measurements. To understand the microscopic physics, it was necessary to downfold exact time- dependent density functional theory to a low energy space of Wannier orbitals. This required developing a rigorous disentanglement procedure to partition the Wannier basis from the rest of the Hilbert space, a necessity for the cuprates due to the strong entanglement between the oxygen p and copper d derived content of the band vstructure. By doing so, I attest that the Mott-gapped collective excitations require a proper treatment of the solid state chemistry inherit to the electronic structure, and they are triggered by the long-ranged dynamically screened Coulomb interaction. In addition, the calculations strongly suggest the ‘fractionalization’ paradigm is not compatible with these materials due to the indiscrimination of the orbital and spin degree of freedom of the Coulomb interaction, in which the collective modes do not simply separate into charge-only, spin-only, and ‘orbital’-only degrees of freedom

    Medium Modifications of Hadron Properties and Partonic Processes

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    Chiral symmetry is one of the most fundamental symmetries in QCD. It is closely connected to hadron properties in the nuclear medium via the reduction of the quark condensate , manifesting the partial restoration of chiral symmetry. To better understand this important issue, a number of Jefferson Lab experiments over the past decade have focused on understanding properties of mesons and nucleons in the nuclear medium, often benefiting from the high polarization and luminosity of the CEBAF accelerator. In particular, a novel, accurate, polarization transfer measurement technique revealed for the first time a strong indication that the bound proton electromagnetic form factors in 4He may be modified compared to those in the vacuum. Second, the photoproduction of vector mesons on various nuclei has been measured via their decay to e+e- to study possible in-medium effects on the properties of the rho meson. In this experiment, no significant mass shift and some broadening consistent with expected collisional broadening for the rho meson has been observed, providing tight constraints on model calculations. Finally, processes involving in-medium parton propagation have been studied. The medium modifications of the quark fragmentation functions have been extracted with much higher statistical accuracy than previously possible.Comment: to appear in J. Phys.: Conf. Proc. "New Insights into the Structure of Matter: The First Decade of Science at Jefferson Lab", eds. D. Higinbotham, W. Melnitchouk, A. Thomas; added reference

    Evidence of Early-Stage Selection on EPAS1 and GPR126 Genes in Andean High Altitude Populations.

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    The aim of this study is to identify genetic variants that harbour signatures of recent positive selection and may facilitate physiological adaptations to hypobaric hypoxia. To achieve this, we conducted whole genome sequencing and lung function tests in 19 Argentinean highlanders (>3500 m) comparing them to 16 Native American lowlanders. We developed a new statistical procedure using a combination of population branch statistics (PBS) and number of segregating sites by length (nSL) to detect beneficial alleles that arose since the settlement of the Andes and are currently present in 15-50% of the population. We identified two missense variants as significant targets of selection. One of these variants, located within the GPR126 gene, has been previously associated with the forced expiratory volume/forced vital capacity ratio. The other novel missense variant mapped to the EPAS1 gene encoding the hypoxia inducible factor 2α. EPAS1 is known to be the major selection candidate gene in Tibetans. The derived allele of GPR126 is associated with lung function in our sample of highlanders (p < 0.05). These variants may contribute to the physiological adaptations to hypobaric hypoxia, possibly by altering lung function. The new statistical approach might be a useful tool to detect selected variants in population studies
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