5,573 research outputs found

    Spectroscopy of the 6p\u3csub\u3e3/2\u3c/sub\u3enp States of Barium

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    The 6p3/2np states of barium have been observed for n values between 14 and 21. The energies, linewidths, and transition strengths have been measured and characterized in terms of one- and two-electron interactions, using a single-configuration approximation

    Air Pollution and Lymphocyte Phenotype Proportions in Cord Blood

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    Effects of air pollution on morbidity and mortality may be mediated by alterations in immune competence. In this study we examined short-term associations of air pollution exposures with lymphocyte immunophenotypes in cord blood among 1,397 deliveries in two districts of the Czech Republic. We measured fine particulate matter < 2.5 μm in diameter (PM(2.5)) and 12 polycyclic aromatic hydrocarbons (PAHs) in 24-hr samples collected by versatile air pollution samplers. Cord blood samples were analyzed using a FACSort flow cytometer to determine phenotypes of CD3(+) T-lymphocytes and their subsets CD4(+) and CD8(+), CD19(+) B-lymphocytes, and natural killer cells. The mothers were interviewed regarding sociodemographic and lifestyle factors, and medical records were abstracted for obstetric, labor and delivery characteristics. During the period 1994 to 1998, the mean daily ambient concentration of PM(2.5) was 24.8 μg/m(3) and that of PAHs was 63.5 ng/m(3). In multiple linear regression models adjusted for temperature, season, and other covariates, average PAH or PM(2.5) levels during the 14 days before birth were associated with decreases in T-lymphocyte phenotype fractions (i.e., CD3(+) CD4(+), and CD8(+)), and a clear increase in the B-lymphocyte (CD19(+)) fraction. For a 100-ng/m(3) increase in PAHs, which represented approximately two standard deviations, the percentage decrease was −3.3% [95% confidence interval (CI), −5.6 to −1.0%] for CD3(+), −3.1% (95% CI, −4.9 to −1.3%) for CD4(+), and −1.0% (95% CI, −1.8 to −0.2%) for CD8(+) cells. The corresponding increase in the CD19(+) cell proportion was 1.7% (95% CI, 0.4 to 3.0%). Associations were similar but slightly weaker for PM(2.5). Ambient air pollution may influence the relative distribution of lymphocyte immunophenotypes of the fetus

    Tax Risk, Corporate Governance, and the Valuation of Tax Avoidance Across Philippine Firms: How Do Investors Value Corporate Tax Avoidance?

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    Tax avoidance has traditionally been thought to enhance firm value because it generates cash savings for reinvestment or distribution to shareholders. More recent literature, however, suggests that tax avoidance valuation may not be so simple. Desai and Dharmapala (2009) introduced the “agency perspective” on tax avoidance, arguing that investors consider the risk of tax avoidance as opening opportunities for managers to extract rents from their firms. Positive tax avoidance value would therefore be conditional on good corporate governance quality. Drake et al. (2017) introduced yet another dimension—tax risk—to the valuation of tax avoidance, arguing that tax avoidance that comes with less variability in tax outcomes (i.e., comes with lower tax risk) should be preferred to those that come with more because investors prefer stable earnings over risky earnings. This policy brief discusses our findings on how public investors in the Philippines value corporate tax avoidance in the contexts of tax risk and corporate governance quality, and policies that can be implemented to enhance firm transparency, increase tax revenues, and raise firm valuations

    Observation of Squeezed Light in the 2  Μm Region

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    We present the generation and detection of squeezed light in the 2  μm wavelength region. This experiment is a crucial step in realizing the quantum noise reduction techniques that will be required for future generations of gravitational-wave detectors. Squeezed vacuum is generated via degenerate optical parametric oscillation from a periodically poled potassium titanyl phosphate crystal, in a dual resonant cavity. The experiment uses a frequency stabilized 1984 nm thulium fiber laser, and squeezing is detected using balanced homodyne detection with extended InGaAs photodiodes. We have measured 4.0±0.1  dB of squeezing and 10.5±0.5  dB of antisqueezing relative to the shot noise level in the audio frequency band, limited by photodiode quantum efficiency. The inferred squeezing level directly after the optical parametric oscillator, after accounting for known losses and phase noise, is 10.7 dB

    Rhesus TRIM5α disrupts the HIV-1 capsid at the inter-hexamer interfaces

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    TRIM proteins play important roles in the innate immune defense against retroviral infection, including human immunodeficiency virus type-1 (HIV-1). Rhesus macaque TRIM5α (TRIM5αrh) targets the HIV-1 capsid and blocks infection at an early post-entry stage, prior to reverse transcription. Studies have shown that binding of TRIM5α to the assembled capsid is essential for restriction and requires the coiled-coil and B30.2/SPRY domains, but the molecular mechanism of restriction is not fully understood. In this study, we investigated, by cryoEM combined with mutagenesis and chemical cross-linking, the direct interactions between HIV-1 capsid protein (CA) assemblies and purified TRIM5αrh containing coiled-coil and SPRY domains (CC-SPRYrh). Concentration-dependent binding of CC-SPRYrh to CA assemblies was observed, while under equivalent conditions the human protein did not bind. Importantly, CC-SPRYrh, but not its human counterpart, disrupted CA tubes in a non-random fashion, releasing fragments of protofilaments consisting of CA hexamers without dissociation into monomers. Furthermore, such structural destruction was prevented by inter-hexamer crosslinking using P207C/T216C mutant CA with disulfide bonds at the CTD-CTD trimer interface of capsid assemblies, but not by intra-hexamer crosslinking via A14C/E45C at the NTD-NTD interface. The same disruption effect by TRIM5αrh on the inter-hexamer interfaces also occurred with purified intact HIV-1 cores. These results provide insights concerning how TRIM5α disrupts the virion core and demonstrate that structural damage of the viral capsid by TRIM5α is likely one of the important components of the mechanism of TRIM5α-mediated HIV-1 restriction. © 2011 Zhao et al

    A sense of embodiment is reflected in people's signature size

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    BACKGROUND: The size of a person's signature may reveal implicit information about how the self is perceived although this has not been closely examined. METHODS/RESULTS: We conducted three experiments to test whether increases in signature size can be induced. Specifically, the aim of these experiments was to test whether changes in signature size reflect a person's current implicit sense of embodiment. Experiment 1 showed that an implicit affect task (positive subliminal evaluative conditioning) led to increases in signature size relative to an affectively neutral task, showing that implicit affective cues alter signature size. Experiments 2 and 3 demonstrated increases in signature size following experiential self-focus on sensory and affective stimuli relative to both conceptual self-focus and external (non-self-focus) in both healthy participants and patients with anorexia nervosa, a disorder associated with self-evaluation and a sense of disembodiment. In all three experiments, increases in signature size were unrelated to changes in self-reported mood and larger than manipulation unrelated variations. CONCLUSIONS: Together, these findings suggest that a person's sense of embodiment is reflected in their signature size

    Broadband reduction of quantum radiation pressure noise via squeezed light injection

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    The Heisenberg uncertainty principle states that the position of an object cannot be known with infinite precision, as the momentum of the object would then be totally uncertain. This momentum uncertainty then leads to position uncertainty in future measurements. When continuously measuring the position of an object, this quantum effect, known as back-action, limits the achievable precision1,2. In audio-band, interferometer-type gravitational-wave detectors, this back-action effect manifests as quantum radiation pressure noise (QRPN) and will ultimately (but does not yet) limit sensitivity3. Here, we present the use of a quantum engineered state of light to directly manipulate this quantum back-action in a system where it dominates the sensitivity in the 10–50 kHz range. We observe a reduction of 1.2 dB in the quantum back-action noise. This experiment is a crucial step in realizing QRPN reduction for future interferometric gravitational-wave detectors and improving their sensitivity
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