On a class of distributions with simple exponential tails

A simple general construction is put forward which covers many unimodal univariate distributions with simple exponentially decaying tails (e.g. asymmetric Laplace, log F and hyperbolic distributions as well as many new models). The proposed family is a special subset of a regular exponential family, and many properties flow therefrom. Two main practical points are made in the context of maximum likelihood fitting of these distributions to data. The first of these is that three, rather than an apparent four, parameters of the distributions suffice. The second is that maximum likelihood estimation of location in the new distributions is precisely equivalent to a standard form of kernel quantile estimation, choice of kernel being equivalent to specific choice of model within the class. This leads to a maximum likelihood method for bandwidth selection in kernel quantile estimation, but its practical performance is shown to be somewhat mixed. Further distribution theoretical aspects are also pursued, particularly distributions related to the main construction as special cases, limiting cases or by simple transformation

Consent bias in research: how to avoid it

See article on page 111

Maximum likelihood method for fitting the Fundamental Plane of the 6dF Galaxy Survey

We have used over 10,000 early-type galaxies from the 6dF Galaxy Survey (6dFGS) to construct the Fundamental Plane across the optical and near-infrared passbands. We demonstrate that a maximum likelihood fit to a multivariate Gaussian model for the distribution of galaxies in size, surface brightness and velocity dispersion can properly account for selection effects, censoring and observational errors, leading to precise and unbiased parameters for the Fundamental Plane and its intrinsic scatter. This method allows an accurate and robust determination of the dependencies of the Fundamental Plane on variations in the stellar populations and environment of early-type galaxies.Comment: 3 pages, 1 figure, to appear in the proceedings of the IAU Symposium 262 "Stellar Populations: Planning for the Next Decade", Charlot and Bruzual ed

Occupational therapy students’ views of health promotion

With the increased interest in the contribution of occupational therapists to health promotion, the College of Occupational Therapists (2004a) recommended that pre-registration programmes should prepare graduates for practice which includes health promotion. This study ascertained the views of second year occupational therapy students about health promotion. Thirty five (30%) students responded to a self report questionnaire and demonstrated positive views about the future relationship between health promotion and occupational therapy. The students thought health promotion should be included in the education of occupational therapists and did not think that there had bee

Spectral reflectivity of solid surfaces at low temperatures

Spectral reflectivity of solid surfaces at low temperature

FT-IR microanalysis of mineral separates from primitive meteorites: techniques, problems and solutions

From the Introduction: We compared several methods of infrared micro spectroscopy using an FT-IR microscope and workbench. This is part of a project to assemble a database of infrared and optical spectra from mineral separates from meteorites, for comparison with astronomical data. Since we usually have to work with small amounts of material (original grain sizes often <50 m), special sample preparation and analytical procedures have to be applied

Acceleration Rates and Injection Efficiencies in Oblique Shocks

The rate at which particles are accelerated by the first-order Fermi mechanism in shocks depends on the angle, \teq{\Tbone}, that the upstream magnetic field makes with the shock normal. The greater the obliquity the greater the rate, and in quasi-perpendicular shocks rates can be hundreds of times higher than those seen in parallel shocks. In many circumstances pertaining to evolving shocks (\eg, supernova blast waves and interplanetary traveling shocks), high acceleration rates imply high maximum particle energies and obliquity effects may have important astrophysical consequences. However, as is demonstrated here, the efficiency for injecting thermal particles into the acceleration mechanism also depends strongly on obliquity and, in general, varies inversely with \teq{\Tbone}. The degree of turbulence and the resulting cross-field diffusion strongly influences both injection efficiency and acceleration rates. The test particle \mc simulation of shock acceleration used here assumes large-angle scattering, computes particle orbits exactly in shocked, laminar, non-relativistic flows, and calculates the injection efficiency as a function of obliquity, Mach number, and degree of turbulence. We find that turbulence must be quite strong for high Mach number, highly oblique shocks to inject significant numbers of thermal particles and that only modest gains in acceleration rates can be expected for strong oblique shocks over parallel ones if the only source of seed particles is the thermal background.Comment: 24 pages including 6 encapsulated figures, as a compressed, uuencoded, Postscript file. Accepted for publication in the Astrophysical Journa

Perceiving infant faces

Evolutionary theories have long been used to generate testable predictions about responses to adult facial cues in the contexts of mate choice, cooperation, and intrasexual competition, among others. More recently, researchers have also used evolutionary theories to guide research on responses to infant facial cues. Here we review some of this work, focusing on research investigating hormonal regulation of responses to infant facial cuteness and the role of kinship cues in perceptions of infant faces. These studies suggest that sex hormones have dissociable effects on the reward value of and perceptual sensitivity to infant facial cuteness. They also suggest that attitudes and behavior toward infants displaying cues of kinship are complex processes influenced by individual differences

FT-IR micro-spectroscopy of fine-grained planetary materials: further results

We present data from FT-IR microspectroscopy of olivines in a thin section of the LL3.6 ordinary chondrite Parnallee. Results are discussed and compared with other methods of FT-IR microspectroscopy