The Blurred Line between Physical Ageing and Mental Health in Older Adults: Implications for the Measurement of Depression

Objectives: Depression in older adults is assessed using measures validated in the general adult population. However, such measures may be inappropriate in the elderly due to the similarities between ageing and the symptoms of depression. This article discusses whether these measures are fit for the purpose and the implications of using inappropriate tools. Methods: A commentary on measuring depression in older adults. Results: Depression symptoms may be mistaken for signs of ageing. Several measures of depression include items that may have a physical cause and thus generate measurement error. Those studies that have assessed the psychometric properties of depression measures in older adults have failed to conduct appropriate assessments of discriminant validity. Discussion: Research is needed to determine whether the conceptual similarity between some symptoms of depression and the effects of ageing translate to factorial similarity. If so, there may be a need for a specific depression measure for older adults that prioritises psychological symptoms

Advanced substructuring techniques Interim report

Digital computer programs for evaluating free undamped vibrational characteristics of structural system

On the Power-Law Tail in the Mass Function of Protostellar Condensations and Stars

We explore the idea that the power-law tail in the mass function of protostellar condensations and stars arises from the accretion of ambient cloud material on to a condensation, coupled with a nonuniform (exponential) distribution of accretion lifetimes. This model allows for the generation of power-law distributions in all star-forming regions, even if condensations start with a lognormal mass distribution, as may be expected from the central limit theorem, and supported by some recent numerical simulations of turbulent molecular clouds. For a condensation mass $m$ with growth rate $dm/dt \propto m$, an analytic three-parameter probability density function is derived; it resembles a lognormal at low mass and has a pure power-law high-mass tail. An approximate power-law tail is also expected for other growth laws, and we calculate the distribution for the plausible case $dm/dt \propto m^{2/3}$. Furthermore, any single time snapshot of the masses of condensations that are still accreting (and are of varying ages) also yields a distribution with a power-law tail similar to that of the IMF.Comment: 5 pages, 4 figures, to appear in MNRAS (Letters section

The Intrinsic Shapes of Molecular Cloud Fragments over a Range of Length Scales

We decipher intrinsic three-dimensional shape distributions of molecular clouds, cloud cores, Bok globules, and condensations using recently compiled catalogues of observed axis ratios for these objects mapped in carbon monoxide, ammonia, through optical selection, or in continuum dust emission. We apply statistical techniques to compare assumed intrinsic axis ratio distributions with observed projected axis ratio distributions. Intrinsically triaxial shapes produce projected distributions which agree with observations. Molecular clouds mapped in $^{12}$CO are intrinsically triaxial but more nearly prolate than oblate, while the smaller cloud cores, Bok globules, and condensations are also intrinsically triaxial but more nearly oblate than prolate.Comment: 12 pages, 11 figures. Version with color figures can be found at http://www.astro.uwo.ca/~cjones/ or http://www.astro.uwo.ca/~basu/. To appear in ApJ, 10 April 2002, v. 569, no.

Coal-rock interface detector

A coal-rock interface detector is presented which employs a radioactive source and radiation sensor. The source and sensor are separately and independently suspended and positioned against a mine surface of hydraulic pistons, which are biased from an air cushioned source of pressurized hydraulic fluid

The mosaics of Mars: As seen by the Viking Lander cameras

The mosaics and derivative products produced from many individual high resolution images acquired by the Viking Lander Camera Systems are described: A morning and afternoon mosaic for both cameras at the Lander 1 Chryse Planitia site, and a morning, noon, and afternoon camera pair at Utopia Planitia, the Lander 11 site. The derived products include special geometric projections of the mosaic data sets, polar stereographic (donut), stereoscopic, and orthographic. Contour maps and vertical profiles of the topography were overlaid on the mosaics from which they were derived. Sets of stereo pairs were extracted and enlarged from stereoscopic projections of the mosaics

Analytic design of a 2.0 GHz space borne linear injected beam crossed field amplifier Final report

High efficiency design for crossed field amplifier for application in synchronous satellite

Vibrational characteristics of linear space frames

Digital computer program for determining modes and frequencies of arbitrary linear space frame