12,796 research outputs found

    Direct photons in d+Au and p+p collisions

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    Results are presented from an ongoing analysis of direct photon production with the STAR experiment at RHIC. The direct photon measurement in d+Au collisions and the neutral pion spectrum in p+p collisions are found to be in agreement with NLO pQCD calculations.Comment: 4 pages, 3 figures, proceedings of Quark Matter 200

    Understanding attitudes toward the control of nonnative wild and feral mammals: similarities and differences in the opinions of the general public, animal protectionists, and conservationists in New Zealand (Aotearoa)

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    Lethal control is used extensively in New Zealand to control non-native non-human mammals. Respondents were surveyed about eight mammal groups considered to be pests and their attitudes towards their control and pest status. They also identified their most appropriate method of control for the eight different mammals. Information was gathered from three groups of respondents: animal protectionists, conservationists and the general public. Conservationists routinely rated all animal groups as more severe pests than the general public or animal protectionists, who provided the lowest scores. Rats, stoats, brushtail possums and rabbits were identified as the four most serious pests by all three groups. Conservationists were 5.7 and 2.6 times more likely to prefer a lethal method of control than protectionists and the general public respectively. For all three groups an increase in pest score for a given animal saw a decline in importance placed upon its welfare. This relationship was strong for the general public but weak for conservationists and animal protectionists. Understanding aspects of potentially opposing viewpoints may be invaluable in supporting the development of new welfare-focused control methods

    Characteristics of ex-racing greyhounds in New Zealand and their impact on re-homing

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    A small proportion of greyhounds surplus to the racing industry are entered into specialist rehoming organisations to be re-purposed as pets. Records of 835 greyhounds, from New Zealand Greyhounds as Pets (GAP), were used to investigate whether pre-adoption characteristics (age, sex, racing record, reason entered) and management factors (temperament test result, foster and trainer effects) had a bearing on rehoming success, and comparisons were made with shelter studies. Rehoming greyhounds as pets is very successful with 85.5% ultimately successfully rehomed. Only 2.9% fail as a result of failed adoptions, 11.6% fail the initial temperament test. Greyhounds were more likely than shelter dogs to pass an initial temperament test and be adopted, and less likely to be returned after 1 month. However, adopted greyhounds were just as likely as shelter dogs to be returned after 6 months. Logistic regression revealed the youngest age group (< 24 months old) were more likely to pass the initial temperament test than older greyhounds. This age effect was not detectable when the adoption success of dogs subsequently available for rehoming was considered, but a sex effect was evident with females more likely to be successfully adopted than males. Whether or not a dog had raced had no significant effect on the likelihood of successful rehoming. Greyhounds passing the temperament test with a basic pass, were less likely to be successfully rehomed than greyhounds scoring a higher pass indicative of lower prey drive. Further investigation of the validity and reliablity of the temperament test is warranted

    A comparative study of functional assays for tissue factor pathway inhibitor using normal plasma and clinical samples

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    Tissue factor pathway inhibitor (TFPI) is a Kunitz-type inhibitor that regulates the initiation of tissue factor-mediated coagulation. Recent reports in the literature have described variable results using different methodologies for TFPI measurement. In this study, we used one clotting and two amidolytic methodologies to assess TFPI functional levels. The study groups included normal healthy donors as well as patients with acute hepatitis, diabetes, coronary artery bypass graft operations, deep vein thrombosis, and prior to and during heparin therapy. The aims were to compare the results obtained in normal plasma using different assay systems, to compare TFPI levels in a range of clinical samples, including those previously not determined using a clotting methodology, and to report TFPI levels in patient groups previously not investigated. The results clearly demonstrate poor correlation between functional TFPI values using the different methodologies, highlighting the requirement for standardization

    Sub-diffraction light propagation in fibers with anisotropic dielectric cores

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    We present a detailed study of light propagation in waveguides with anisotropic metamaterial cores. We demonstrate that in contrast to conventional optical fibers, our structures support free-space-like propagating modes even when the waveguide radius is much smaller than the wavelength. We develop analytical formalism to describe mode structure and propagation in strongly anisotropic systems and study the effects related to waveguide boundaries and material composition

    Effect of polarized optical injection on the wavelength polarization switching and bistability of a 1550nm-VCSEL

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    We report the first experimental observation of a variety of forms of wavelength polarization switching and bistability with a 1550-nm VCSEL subject to optical injection with different input polarization angles. ©2008 IEEE

    Effects of detuning, gain-guiding, and index antiguiding on the dynamics of two laterally coupled semiconductor lasers

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    Four examples of laterally coupled semiconductor lasers with different waveguiding structures have been studied using coupled mode theory and allowing for frequency detuning between the lasers. The structures include purely real index guiding, pure gain-guiding, and combinations of index guiding and antiguiding with gain-guiding. The dynamics of these four systems have been explored using AUTO software (standard numerical continuation package), linear stability analysis, and direct integration of the rate equations. Convincing agreement between results obtained by these three methods has been demonstrated, including effects due to variation of laser pumping rate, detuning, and linewidth enhancement factor. A periodicity of behavior with laser separation has been revealed that was previously overlooked. This periodicity has increasing influence on the bifurcations of the system as the structures develop from those with purely real guidance to a combination of index antiguiding and gain-guiding. The laser design and operating parameters used are realistic for a wide range of edge-emitting and surface-emitting lasers of practical importance, so that the dynamics studied here are relevant to real systems of coupled lasers

    Mapping bifurcation structure and parameter dependence in quantum dot spin-VCSELs

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    We consider a modified version of the spin-flip model (SFM) that describes optically pumped quantum dot (QD) spin-polarized vertical-cavity surface-emitting lasers (VCSELs). Maps showing different dynamical regions and those consisting of various key bifurcations are constructed by direct numerical simulations and a numerical path continuation technique, respectively. A comparison between them clarifies the physical mechanism that governs the underlying dynamics as well as routes to chaos in QD spin-VCSELs. Detailed numerical simulations illustrate the role played by the capture rate from wetting layer (WL) to QD ground state, the gain parameter, and the amplitude-phase coupling. By tuning the aforementioned key parameters in turn we show how the dynamical regions evolve as a function of the intensity and polarization of the optical pump, as well as in the plane of the spin relaxation rate and linear birefringence rate, which is of importance in the design of spin lasers promising potential applications. By increasing the capture rate from WL to QD our simulation accurately describes the transition from the QD spin-VCSEL to the quantum well case, in agreement with a previous mathematical derivation, and thus validates the modified SFM equations

    Characterising epithelial tissues using persistent entropy

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    In this paper, we apply persistent entropy, a novel topological statistic, for characterization of images of epithelial tissues. We have found out that persistent entropy is able to summarize topological and geometric information encoded by \alpha-complexes and persistent homology. After using some statistical tests, we can guarantee the existence of significant differences in the studied tissues.Comment: 12 pages, 7 figures, 4 table
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