9,985 research outputs found

    No preference in female sika deer for conspecific over heterospecific male sexual calls in a mate choice context

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    Mating signals can be used both in contexts of species recognition and mate quality assessment. This study examines species recognition abilities in oestrous females presented with male mating calls from both conspecifics and closely related allopatric heterospecifics. Red deer and sika deer are naturally allopatric polygynous species capable of hybridization during sympatry. Male mating calls are sexually selected and differ greatly between species. Previous work indicated that most but not all oestrous red deer hinds prefer male mating calls from conspecifics over heterospecific sika deer. Using two-speaker playback experiments, we extend this examination by measuring the preference responses of oestrous sika deer hinds to these stimuli. We predicted that oestrous sika deer hinds will show little flexibility in behavioural responses and prefer conspecific calls over heterospecific calls, similar to those of red deer hinds. In contrast, sika deer hinds showed high levels of flexibility and no difference in overall preference behaviours, suggesting that vocal behaviour does not provide a solid barrier to hybridization in this species. The asymmetry in heterospecific preference responses between these species is discussed in relation to possible causation and hybridization patterns observed in free-ranging populations

    Making meaningful decisions about time, workload and pedagogy in the digital age: the Course Resource Appraisal Model

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    This article reports on a design-based research project to create a modelling tool to analyse the costs and learning benefits involved in different modes of study. The Course Resource Appraisal Model (CRAM) provides accurate cost-benefit information so that institutions are able to make more meaningful decisions about which kind of courses—online, blended or traditional face-to-face—make sense for them to provide. The tool calculates the difference between expenses and income over three iterations of the course and presents a pedagogical analysis of the learning experience provided. The article draws on a CRAM analysis of the costs and learning benefits of a massive open online course to show how the tool can illuminate the pedagogical and financial viability of a course of this kind

    Temperature-tuning of near-infrared monodisperse quantum dot solids at 1.5 um for controllable Forster energy transfer

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    We present the first time-resolved cryogenic observations of Forster energy transfer in large, monodisperse lead sulphide quantum dots with ground state transitions near 1.5 um (0.83 eV), in environments from 160 K to room temperature. The observed temperature-dependent dipole-dipole transfer rate occurs in the range of (30-50 ns)^(-1), measured with our confocal single-photon counting setup at 1.5 um wavelengths. By temperature-tuning the dots, 94% efficiency of resonant energy transfer can be achieved for donor dots. The resonant transfer rates match well with proposed theoretical models

    Evaluation of Education and Other Influential Factors on the Perceptions of Influenza Vaccinations

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    Influenza is a potentially deadly contagious viral infection that attacks the respiratory system. The 1918 influenza pandemic infected approximately 1/3 of the world’s population and resulted in an estimated 50 million deaths globally. Research has led to the production of influenza vaccinations. Unfortunately, there continues to be influenza epidemics that are responsible for killing numerous people annually. One reason for the continued death toll from influenza is the lack of people receiving a yearly flu vaccination. In order to gain more public acceptance for influenza vaccinations, it is important to understand the factors influencing the choice to be vaccinated. A study was conducted on 191 undergraduate general psychology students at the University of Central Arkansas to test if specific factors determine the predictability of vaccination acceptance. Education and positive influential factors toward flu vaccinations are two important factors presented in the study that have influence on participants receiving the vaccine. The study results are beneficial in understanding why people reject flu vaccines and what can be done to reverse those decisions

    Simulations of slow positron production using a low energy electron accelerator

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    Monte Carlo simulations of slow positron production via energetic electron interaction with a solid target have been performed. The aim of the simulations was to determine the expected slow positron beam intensity from a low energy, high current electron accelerator. By simulating (a) the fast positron production from a tantalum electron-positron converter and (b) the positron depth deposition profile in a tungsten moderator, the slow positron production probability per incident electron was estimated. Normalizing the calculated result to the measured slow positron yield at the present AIST LINAC the expected slow positron yield as a function of energy was determined. For an electron beam energy of 5 MeV (10 MeV) and current 240 μ\muA (30 μ\muA) production of a slow positron beam of intensity 5 ×\times 106^{6} s1^{-1} is predicted. The simulation also calculates the average energy deposited in the converter per electron, allowing an estimate of the beam heating at a given electron energy and current. For low energy, high-current operation the maximum obtainable positron beam intensity will be limited by this beam heating.Comment: 11 pages, 15 figures, submitted to Review of Scientific Instrument

    Do red deer hinds prefer stags that produce harsh roars in mate choice contexts?

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    Red deer stags give two types of roars during the breeding season, termed ‘common’ and ‘harsh’ roars. This study tested the hypothesis that the characteristic spectro-temporal structure of male harsh roars functions to directly attract females towards male callers during the breeding season. The results show that oestrous hinds look for longer towards speakers broadcasting sequences containing harsh roars, but do not preferentially approach or spend more time in close proximity to speakers broadcasting harsh roars over those broadcasting only common roars. While these observations confirm that the specific acoustic structure of male harsh roars functions to draw the attention of hinds, they are not consistent with the notion that these calls have an immediate impact on mate choice decisions by stimulating oestrous hinds to move towards male callers. Consequently, we suggest that intersexual selection through female mate choice is unlikely to be a major factor driving the evolution of male red deer harsh roars

    GWmodel: an R package for exploring spatial heterogeneity using geographically weighted models

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    Spatial statistics is a growing discipline providing important analytical techniques in a wide range of disciplines in the natural and social sciences. In the R package GWmodel we present techniques from a particular branch of spatial statistics, termed geographically weighted (GW) models. GW models suit situations when data are not described well by some global model, but where there are spatial regions where a suitably localized calibration provides a better description. The approach uses a moving window weighting technique, where localized models are found at target locations. Outputs are mapped to provide a useful exploratory tool into the nature of the data spatial heterogeneity. Currently, GWmodel includes functions for: GW summary statistics, GW principal components analysis, GW regression, and GW discriminant analysis; some of which are provided in basic and robust forms

    Tuning localized plasmons in nanostructured substrates for surface-enhanced Raman scattering

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    Comprehensive reflectivity mapping of the angular dispersion of nanostructured arrays comprising of inverted pyramidal pits is demonstrated. By comparing equivalently structured dielectric and metallic arrays, diffraction and plasmonic features are readily distinguished. While the diffraction features match expected theory, localised plasmons are also observed with severely flattened energy dispersions. Using pit arrays with identical pitch, but graded pit dimensions, energy scaling of the localised plasmon is observed. These localised plasmons are found to match a simple model which confines surface plasmons onto the pit sidewalls thus allowing an intuitive picture of the plasmons to be developed. This model agrees well with a 2D finite-difference time-domain simulation which shows the same dependence on pit dimensions. We believe these tuneable plasmons are responsible for the surface-enhancement of the Raman scattering (SERS) of an attached layer of benzenethiol molecules. Such SERS substrates have a wide range of applications both in security, chemical identification, environmental monitoring and healthcare
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