4,821 research outputs found

    Uncountably many quasi-isometry classes of groups of type FPFP

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    Previously one of the authors constructed uncountable families of groups of type FPFP and of nn-dimensional Poincar\'e duality groups for each n4n\geq 4. We strengthen these results by showing that these groups comprise uncountably many quasi-isometry classes. We deduce that for each n4n\geq 4 there are uncountably many quasi-isometry classes of acyclic nn-manifolds admitting free cocompact properly discontinuous discrete group actions.Comment: Version 2: minor corrections made, theorems now numbered by sectio

    A Molecular Platinum Cluster Junction: A Single-Molecule Switch

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    We present a theoretical study of the electronic transport through single-molecule junctions incorporating a Pt6 metal cluster bound within an organic framework. We show that the insertion of this molecule between a pair of electrodes leads to a fully atomically engineered nano-metallic device with high conductance at the Fermi level and two sequential high on/off switching states. The origin of this property can be traced back to the existence of a HOMO which consists of two degenerate and asymmetric orbitals, lying close in energy to the Fermi level of the metallic leads. Their degeneracy is broken when the molecule is contacted to the leads, giving rise to two resonances which become pinned close to the Fermi level and display destructive interference.Comment: 4 pages, 4 figures. Reprinted (adapted) with permission from J. Am. Chem. Soc., 2013, 135 (6), 2052. Copyright 2013 American Chemical Societ

    Fault-Zone Waves Observed at the Southern Joshua Tree Earthquake Rupture Zone

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    Waveform and spectral characteristics of several aftershocks of the M 6.1 22 April 1992 Joshua Tree earthquake recorded at stations just north of the Indio Hills in the Coachella Valley can be interpreted in terms of waves propagating within narrow, low-velocity, high-attenuation, vertical zones. Evidence for our interpretation consists of: (1) emergent P arrivals prior to and opposite in polarity to the impulsive direct phase; these arrivals can be modeled as headwaves indicative of a transfault velocity contrast; (2) spectral peaks in the S wave train that can be interpreted as internally reflected, low-velocity fault-zone wave energy; and (3) spatial selectivity of event-station pairs at which these data are observed, suggesting a long, narrow geologic structure. The observed waveforms are modeled using the analytical solution of Ben-Zion and Aki (1990) for a plane-parallel layered fault-zone structure. Synthetic waveform fits to the observed data indicate the presence of NS-trending vertical fault-zone layers characterized by a thickness of 50 to 100 m, a velocity decrease of 10 to 15% relative to the surrounding rock, and a P-wave quality factor in the range 25 to 50

    Synthesis of fluorinated oxygen- and sulfur-containing heteroaromatics

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    Milk protein concentrate (79% protein) reconstituted at 13.5% (w/v) protein was heated (90 °C, 25 min, pH 7.2) with or without added calcium chloride. After fractionation of the casein and whey protein aggregates by fast protein liquid chromatography, the heat stability (90 °C, up to 1 h) of the fractions (0.25%, w/v, protein) was assessed. The heat-induced aggregates were composed of whey protein and casein, in whey protein:casein ratios ranging from 1:0.5 to 1:9. The heat stability was positively correlated with the casein concentration in the samples. The samples containing the highest proportion of caseins were the most heat-stable, and close to 100% (w/w) of the aggregates were recovered post-heat treatment in the supernatant of such samples (centrifugation for 30 min at 10,000 × g). κ-Casein appeared to act as a chaperone controlling the aggregation of whey proteins, and this effect was stronger in the presence of αS- and β-casein

    Realizing Opportunities in Forest Growth Modelling

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    The world is continually changing: the emergence of new technology and new demands for pertinent information pose new challenges and possibilities for forest management. Are forest growth models keeping up with client needs? To remain relevant, modelers need to anticipate client needs, gauge the data needed to satisfy these demands, develop the tools to collect and analyze these data efficiently, and resolve how best to deliver the resulting models and other findings. Researchers and managers should jointly identify and articulate anticipated needs for the future, and initiate action to satisfy them. New technology that offers potential for innovation in forest growth modelling include modelling software, automated data collection, and animation of model outputs. New sensors in the sky and on forest machines can routinely provide data previously considered unattainable (e.g., tree coordinates, crown dimensions), as census rather than sample data. What does this revolution in data availability imply for forest growth models, especially for our choice of driving variables

    Observation of Interaction of Spin and Intrinsic Orbital Angular Momentum of Light

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    Interaction of spin and intrinsic orbital angular momentum of light is observed, as evidenced by length-dependent rotations of both spatial patterns and optical polarization in a cylindrically-symmetric isotropic optical fiber. Such rotations occur in straight few-mode fiber when superpositions of two modes with parallel and anti-parallel orientation of spin and intrinsic orbital angular momentum (IOAM=22\hslash) are excited, resulting from a degeneracy splitting of the propagation constants of the modes.Comment: 6 pages, 5 figures, and a detailed supplement. Version 3 corrects a typo and adds the journal referenc

    Which patients are assessed by lung cancer nurse specialists? A national lung cancer audit study of over 128,000 patients across England

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    Background: Lung cancer nurse specialists (LCNS) are integral to the multidisciplinary clinical team, providing personalised physical and psycho-social interventions, and care management for people with lung cancer. The National Institute of Health and Care Excellence (NICE) recommend that all patients have access to a LCNS. We conducted a national study assessing whether there is variation in access to and timing of LCNS assessment. Methods: The National Cancer Action Team’s LCNS workforce census in England was linked with patient and hospital Trust data from the English National Lung Cancer Audit. Multivariate logistic regression was used to assess features associated with LCNS assessment. Results: 128,124 lung cancer patients were seen from 2007 to 2011. LCNS assessment confirmation was ‘yes’ in 62%, ‘no’ in 6% and ‘missing’ in 32%. Where (in clinic versus ward) and when (before versus after diagnosis) patients were assessed by a LCNS also varied. Older patients with poor performance status, early cancer stage, and comorbidities were less likely to be assessed; there was no difference with sex or socioeconomic group. Patients receiving any anti-cancer treatment were more likely to be assessed. Assessment was lower in Trusts with high annual patient numbers (odds ratio = 0.58, 95% confidence interval 0.37–0.91) and where LCNS caseload > 250 (0.69, 0.41–1.16, although not statistically significant), but increased where workload was conducted mostly by band 8 nurses (2.22, 1.22–4.02). Conclusion: LCNS assessment varied by patient and Trust features, which may indicate unmet need for some patients. The current workforce needs to expand as well as retain experienced LCNSs

    Simulations and cosmological inference: A statistical model for power spectra means and covariances

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    We describe an approximate statistical model for the sample variance distribution of the non-linear matter power spectrum that can be calibrated from limited numbers of simulations. Our model retains the common assumption of a multivariate Normal distribution for the power spectrum band powers, but takes full account of the (parameter dependent) power spectrum covariance. The model is calibrated using an extension of the framework in Habib et al. (2007) to train Gaussian processes for the power spectrum mean and covariance given a set of simulation runs over a hypercube in parameter space. We demonstrate the performance of this machinery by estimating the parameters of a power-law model for the power spectrum. Within this framework, our calibrated sample variance distribution is robust to errors in the estimated covariance and shows rapid convergence of the posterior parameter constraints with the number of training simulations.Comment: 14 pages, 3 figures, matches final version published in PR

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

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    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

    Dynactin-dependent cortical dynein and spherical spindle shape correlate temporally with meiotic spindle rotation in Caenorhabditis elegans.

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    Oocyte meiotic spindles orient with one pole juxtaposed to the cortex to facilitate extrusion of chromosomes into polar bodies. In Caenorhabditis elegans, these acentriolar spindles initially orient parallel to the cortex and then rotate to the perpendicular orientation. To understand the mechanism of spindle rotation, we characterized events that correlated temporally with rotation, including shortening of the spindle in the pole-to pole axis, which resulted in a nearly spherical spindle at rotation. By analyzing large spindles of polyploid C. elegans and a related nematode species, we found that spindle rotation initiated at a defined spherical shape rather than at a defined spindle length. In addition, dynein accumulated on the cortex just before rotation, and microtubules grew from the spindle with plus ends outward during rotation. Dynactin depletion prevented accumulation of dynein on the cortex and prevented spindle rotation independently of effects on spindle shape. These results support a cortical pulling model in which spindle shape might facilitate rotation because a sphere can rotate without deforming the adjacent elastic cytoplasm. We also present evidence that activation of spindle rotation is promoted by dephosphorylation of the basic domain of p150 dynactin
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