Creating and validating self-efficacy scales for students

Purpose: student radiographers must possess certain abilities to progress in their training; these can be assessed in various ways. Bandura’s social cognitive theory identifies self-efficacy as a key psychological construct with regard to how people adapt to environments where new skills are developed. Use of this construct is common in health care literature but little has been noted within radiographic literature. The authors sought to develop a self-efficacy scale for student radiographers. Method: the scale was developed following a standard format. An initial pool of 80 items was generated and psychometric analysis was used to reduce this to 68 items. Radiography students drawn from 7 universities were participants (N=198) in validating the scale. Results: the psychometric properties of the scale were examined using analysis of variance (ANOVA), factor analysis and item analysis. ANOVA demonstrated an acceptable level of known group validity: first-year, second-year, and third-year students all scored significantly differently (P=.035) from one another. Factor analysis identified the most significant factor as confidence in image appraisal. The scale was refined using item and factor analysis to produce the final 25-item scale. Conclusion This is the first published domain-specific self-efficacy scale validated specifically for student radiographers. In its current format it may have pedagogical utility. The authors currently are extending the work to add to the scale’s validity and embedding it into student training to assess its predictive value

Propagating Residual Biases in Cosmic Shear Power Spectra

In this paper we derive a full expression for the propagation of multiplicative and additive shape measurement biases into the cosmic shear power spectrum. In doing so we identify several new terms that are associated with selection effects, as well as cross-correlation terms between the multiplicative and additive biases and the shear field. The computation of the resulting bias in the shear power spectrum scales as the fifth power of the maximum multipole considered. Consequently the calculation is unfeasible for large l-modes, and the only tractable way to assess the full impact of shape measurement biases on cosmic shear power spectrum is through forward modelling of the effects. To linear order in bias parameters the shear power spectrum is only affected by the mean of the multiplicative bias field over a survey and the cross correlation between the additive bias field and the shear field. If the mean multiplicative bias is zero then second order convolutive terms are expected to be orders of magnitude smaller.Comment: 10 pages, accepted to the Open Journal of Astrophysic

Failure of vaccination to prevent outbreaks of foot-and-mouth disease

Outbreaks of foot-and-mouth disease persist in dairy cattle herds in Saudi Arabia despite revaccination at intervals of 4-6 months. Vaccine trials provide data on antibody responses following vaccination. Using this information we developed a mathematical model of the decay of protective antibodies with which we estimated the fraction of susceptible animals at a given time after vaccination. The model describes the data well, suggesting over 95% take with an antibody half-life of 43 days. Farm records provided data on the time course of five outbreaks. We applied a 'SLIR' epidemiological model to these data, fitting a single parameter representing disease transmission rate. The analysis provides estimates of the basic reproduction number R(0), which may exceed 70 in some cases. We conclude that the critical intervaccination interval which would provide herd immunity against FMDV is unrealistically short, especially for heterologous challenge. We suggest that it may not be possible to prevent foot-and-mouth disease outbreaks on these farms using currently available vaccines

Detection of a single cobalt microparticle with a microfabricated atomic magnetometer

We present magnetic detection of a single, 2 {\mu}m diameter cobalt microparticle using an atomic magnetometer based on a microfabricated vapor cell. These results represent an improvement by a factor of 105 in terms of the detected magnetic moment over previous work using atomic magnetometers to detect magnetic microparticles. The improved sensitivity is due largely to the use of small vapor cells. In an optimized setup, we predict detection limits of 0.17 {\mu}m^3.Comment: 3 pages, 3 figure

Propagating Residual Biases in Cosmic Shear Power Spectra

In this paper we derive a full expression for the propagation of multiplicative and additive shape measurement biases into the cosmic shear power spectrum. In doing so we identify several new terms that are associated with selection effects, as well as cross-correlation terms between the multiplicative and additive biases and the shear field. The computation of the resulting bias in the shear power spectrum scales as the fifth power of the maximum multipole considered. Consequently the calculation is unfeasible for large l-modes, and the only tractable way to assess the full impact of shape measurement biases on cosmic shear power spectrum is through forward modelling of the effects. To linear order in bias parameters the shear power spectrum is only affected by the mean of the multiplicative bias field over a survey and the cross correlation between the additive bias field and the shear field. If the mean multiplicative bias is zero then second order convolutive terms are expected to be orders of magnitude smaller

First record of Triassic Rhynchosauria (Reptilia: Diapsida) from the Lower Zambezi Valley, Zimbabwe

True rhynchosaurids are described from Zimbabwe for the first time. The fossils occur as partially associated skeletons and scattered isolates in upward-fining, micaceous fluvial sandstones of the Pebbly Arkose Formation (late Triassic) in the Western Cabora Bassa Basin, Lower Zambezi Valley. On the grounds that the dentary of the Zimbabwean form possesses a row of small, conical lingual teeth in addition to a palisade row of penicillate teeth on the occlusal surface, it is concluded that the taxon present is Hyperodapedon sp., and that it is closely related to a rhynchosaurid described from Tanzania. One bone identified as a prosauropod dinosaurian femur was found associated with the Zimbabwean rhynchosaurids. The late Triassic age suggested by the presence of advanced rhynchosaurids is supported by the occurrence of the typical Triassic fossil plant genus Dicroidium, and by the general stratigraphy of the beds which contain the fossils (i.e. the fossil-bearing beds are underlain by beds of mid-Triassic age or younger, and are overlain by beds of latest Triassic or early Jurassic age

Propagating residual biases in masked cosmic shear power spectra

In this paper we derive a full expression for the propagation of weak lensing shape measurement biases into cosmic shear power spectra including the effect of missing data. We show using simulations that terms higher than first order in bias parameters can be ignored and the impact of biases can be captured by terms dependent only on the mean of the multiplicative bias field. We identify that the B-mode power contains information on the multiplicative bias. We find that without priors on the residual multiplicative bias $\delta m$ and stochastic ellipticity variance $\sigma_e$ that constraints on the amplitude of the cosmic shear power spectrum are completely degenerate, and that when applying priors the constrained amplitude $A$ is slightly biased low via a classic marginalisation paradox. Using all-sky Gaussian random field simulations we find that the combination of $(1+2\delta m)A$ is unbiased for a joint EE and BB power spectrum likelihood if the error and mean (precision and accuracy) of the stochastic ellipticity variance is known to better than $\sigma(\sigma_e)\leq 0.05$ and $\Delta\sigma_e\leq 0.01$, or the multiplicative bias is known to better than $\sigma(m)\leq 0.07$ and $\Delta m\leq 0.01$.Comment: 12 pages, accepted to the Open Journal of Astrophysics, comments welcom

Weak lensing analysis in three dimensions

We present a comprehensive full-sky 3-dimensional analysis of the weak-lensing fields and their corresponding power spectra. Using the formalism of spin-weight spherical harmonics and spherical Bessel functions, we relate the two-point statistics of the harmonic expansion coefficients of the weak lensing shear and convergence to the power spectrum of the matter density perturbations, and derive small-angle limits. Such a study is relevant in view of the next generation of large-scale weak lensing surveys which will provide distance information about the sources through photometric redshifts. This opens up the possibility of accurate cosmological parameter estimation via weak lensing, with an emphasis on the equation of state of dark energy.Comment: 23 pages, 4 figures, accepted by Phys.Rev.D; replaced with revised version, minor corrections, all figures done with better samplin