911 research outputs found

    A Melding of the Minds: When Primatology Meets Personality and Social Psychology

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    Social/personality psychology and behavioral primatology both enjoy long histories of research aimed at uncovering the proximate and ultimate determinants of primate--human and nonhuman--social behavior. Although they share research themes, methodologies and theories, and their studied species are closely related, there is currently very little interaction between the fields. This separation means that researchers in these disciplines miss out on opportunities to advance understanding by combining insights from both fields. Social/personality psychologists additionally miss the opportunity for a phylogenetic analysis. The time has come to integrate perspectives on primate social psychology. Here we provide a historical background and document the main similarities and differences in approaches. Next we present some examples of research programs that may benefit from an integrated primate perspective. Finally, we propose a framework for developing a social psychology inclusive of all primates. Such a melding of minds promises to greatly benefit those who undertake the challenge

    Modelling microelectrode biosensors : free-flow calibration can substantially underestimate tissue concentrations

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    Microelectrode amperometric biosensors are widely used to measure concentrations of analytes in solution and tissue including acetylcholine, adenosine, glucose and glutamate. A great deal of experimental and modelling effort has been directed at quantifying the response of the biosensors themselves; however, the influence that the macroscopic tissue environment has on biosensor response has not been subjected to the same level of scrutiny. Here we identify an important issue in the way microelectrode biosensors are calibrated that is likely to have led to underestimations of analyte tissue concentrations. Concentration in tissue is typically determined by comparing the biosensor signal to that measured in free-flow calibration conditions. In a free-flow environment the concentration of the analyte at the outer surface of the biosensor can be considered constant. However, in tissue the analyte reaches the biosensor surface by diffusion through the extracellular space. Because the enzymes in the biosensor break down the analyte, a density gradient is set up resulting in a significantly lower concentration of analyte near the biosensor surface. This effect is compounded by the diminished volume fraction (porosity) and reduction in the diffusion coefficient due to obstructions (tortuosity) in tissue. We demonstrate this effect through modelling and experimentally verify our predictions in diffusive environments

    Phosphorescence and donor-acceptor pair recombination in laboratory-grown diamonds

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    Intense "blue-green" phosphorescence is commonly observed in near colourless lab-grown high-pressure high-temperature (HPHT) diamonds following optical excitation at or above the indirect bandgap. We have employed a holistic combination of optically-excited time-resolved techniques (in addition to standard spectroscopic characterisation techniques) to study the physics of this long-lived phosphorescence and understand luminescence-related charge transfer processes. It is shown that the properties of the broad "blue-green" luminescence and phosphorescence band can be fully explained by emission from neutral substitutional nitrogen-boron donor-acceptor pairs (NS0\text{N}_\text{S}^0...BS0\text{B}_\text{S}^0) , once the configurational change between charge states is considered, and both tunneling between defects and thermal ionization of donors and acceptors is considered. Significant concentrations of metastable NS−\text{N}_\text{S}^-, are identified after optical excitation at or above the indirect bandgap. NS−\text{N}_\text{S}^- is much shallower (∼\sim0.2 eV) than previously thought and plays a key role in resetting the NS0\text{N}_\text{S}^0...BS0\text{B}_\text{S}^0 donor-acceptor pairs.Comment: 15 pages, 13 figure

    All-optical hyperpolarization of electron and nuclear spins in diamond

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    Low thermal polarization of nuclear spins is a primary sensitivity limitation for nuclear magnetic resonance. Here we demonstrate optically pumped (microwave-free) nuclear spin polarization of 13C^{13}\mathrm{C} and 15N^{15}\mathrm{N} in 15N^{15}\mathrm{N}-doped diamond. 15N^{15}\mathrm{N} polarization enhancements up to −2000-2000 above thermal equilibrium are observed in the paramagnetic system Ns0\mathrm{N_s}^{0}. Nuclear spin polarization is shown to diffuse to bulk 13C^{13}\mathrm{C} with NMR enhancements of −200-200 at room temperature and −500-500 at 240 K\mathrm{240~K}, enabling a route to microwave-free high-sensitivity NMR study of biological samples in ambient conditions.Comment: 5 pages, 5 figure

    A genome-wide association study demonstrates significant genetic variation for fracture risk in Thoroughbred racehorses

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    Background: Thoroughbred racehorses are subject to non-traumatic distal limb bone fractures that occur during racing and exercise. Susceptibility to fracture may be due to underlying disturbances in bone metabolism which have a genetic cause. Fracture risk has been shown to be heritable in several species but this study is the first genetic analysis of fracture risk in the horse. Results: Fracture cases (n = 269) were horses that sustained catastrophic distal limb fractures while racing on UK racecourses, necessitating euthanasia. Control horses (n = 253) were over 4 years of age, were racing during the same time period as the cases, and had no history of fracture at the time the study was carried out. The horses sampled were bred for both flat and National Hunt (NH) jump racing. 43,417 SNPs were employed to perform a genome-wide association analysis and to estimate the proportion of genetic variance attributable to the SNPs on each chromosome using restricted maximum likelihood (REML). Significant genetic variation associated with fracture risk was found on chromosomes 9, 18, 22 and 31. Three SNPs on chromosome 18 (62.05 Mb – 62.15 Mb) and one SNP on chromosome 1 (14.17 Mb) reached genome-wide significance (p <0.05) in a genome-wide association study (GWAS). Two of the SNPs on ECA 18 were located in a haplotype block containing the gene zinc finger protein 804A (ZNF804A). One haplotype within this block has a protective effect (controls at 1.95 times less risk of fracture than cases, p = 1 × 10-4), while a second haplotype increases fracture risk (cases at 3.39 times higher risk of fracture than controls, p = 0.042). Conclusions: Fracture risk in the Thoroughbred horse is a complex condition with an underlying genetic basis. Multiple genomic regions contribute to susceptibility to fracture risk. This suggests there is the potential to develop SNP-based estimators for genetic risk of fracture in the Thoroughbred racehorse, using methods pioneered in livestock genetics such as genomic selection. This information would be useful to racehorse breeders and owners, enabling them to reduce the risk of injury in their horses

    Production of oriented nitrogen-vacancy color centers in synthetic diamond

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    The negatively charged nitrogen-vacancy (NV-) center in diamond is an attractive candidate for applications that range from magnetometry to quantum information processing. Here we show that only a fraction of the nitrogen (typically < 0.5 %) incorporated during homoepitaxial diamond growth by Chemical Vapor Deposition (CVD) is in the form of undecorated NV- centers. Furthermore, studies on CVD diamond grown on (110) oriented substrates show a near 100% preferential orientation of NV- centers along only the [111] and [-1-11] directions, rather than the four possible orientations. The results indicate that NV centers grow in as units, as the diamond is deposited, rather than by migration and association of their components. The NV unit of the NVH- is similarly preferentially oriented, but it is not possible to determine whether this defect was formed by H capture at a preferentially aligned NV center or as a complete unit. Reducing the number of NV orientations from 4 orientations to 2 orientations should lead to increased optically-detected magnetic resonance contrast and thus improved magnetic sensitivity in ensemble-based magnetometry.Comment: 13 Pages (inlcuding suplementary information), 4 figure

    Deep three-dimensional solid-state qubit arrays with long-lived spin coherence

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    Nitrogen-vacancy centers (NVCs) in diamond show promise for quantum computing, communication, and sensing. However, the best current method for entangling two NVCs requires that each one is in a separate cryostat, which is not scalable. We show that single NVCs can be laser written 6–15-µm deep inside of a diamond with spin coherence times that are an order of magnitude longer than previous laser-written NVCs and at least as long as naturally occurring NVCs. This depth is suitable for integration with solid immersion lenses or optical cavities and we present depth-dependent T2 measurements. 200 000 of these NVCs would fit into one diamond

    Laser writing of individual atomic defects in a crystal with near-unity yield

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    Atomic defects in wide band gap materials show great promise for development of a new generation of quantum information technologies, but have been hampered by the inability to produce and engineer the defects in a controlled way. The nitrogen-vacancy (NV) color center in diamond is one of the foremost candidates, with single defects allowing optical addressing of electron spin and nuclear spin degrees of freedom with potential for applications in advanced sensing and computing. Here we demonstrate a method for the deterministic writing of individual NV centers at selected locations with high positioning accuracy using laser processing with online fluorescence feedback. This method provides a new tool for the fabrication of engineered materials and devices for quantum technologies and offers insight into the diffusion dynamics of point defects in solids.Comment: 16 pages, 8 figure
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