12,931 research outputs found

    Selecting Windows

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    Covers double-hung, horizontal sliding, casement, awning, jalousie, top-hinged, and fixed windows. Includes patio doors and skylights

    Asteroid Cooling Rates Indicated by K-Feldspar Exsolution Textures in H4 Ordinary Chondrites

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    Undisturbed thermal metamorphism in ordinary chondrite (OC) asteroids, produced through the radioactive decay of 26Al, is expected to result in an onion-shell-like structure. In such a structure, the inner layers of the asteroid experience more extensive thermal metamorphism, as represented by higher petrologic type, than the exterior layers. Furthermore, cooling rates are expected to be slower for OCs of high petrologic type than those of low petrologic type. However, cooling rates determined using metallographic methods and pyroxene diffusion are inconsistent with onion-shell-style cooling and have resulted in new models. These models argue for the disruption of the asteroid after peak metamorphism followed by reaccretion into a rubble pile. Improved constraints on cooling rates would provide a better understanding of the timing and scale of disruptive events. Feldspar microtextures are another tool that can be used to determine asteroid cooling rates. In OC chondrules, plagioclase is present as either a primary phase, or a secondary phase forming from the crystallization of mesostasis glass through petrologic type 4, followed by chemical and textural equilibration. Potas-sium feldspar is observed in petrologic types 3.6-6, as either patches or lamellae exsolved from albite in a perthite texture, often near pores or fractures. Exsolution occurs most commonly, and most extensively, in petrologic type 4. Because the feldspar exsolution wavelength is related to the rate at which grains cooled from the solvus temperature, determined from the minerals bulk composition, the chondrite cooling rate can be measured from regions of exsolution. We have previously reported the perthite exsolution cooling rate of Avanhandava, an H4 chondrite, to be 1 C per 1-4 months over a temperature interval of 765-670 C. A peristerite exsolution texture was also present in the Na-rich lamellae for which we estimated a cooling rate of 1 C in 103-104 years from 570-540 C. Overall, the cooling rates determined from Avanhandava are consistent with pyroxene diffusion (fast cooling at high temperatures) and metallographic rates (slow cooling at low temperatures), hence with the rubble pile model of disruption and reaccretion. Here, we characterize feldspar microtextures in four additional H4 chondrites to test the consistency of feldspar cooling rates across a range of samples. We show that all H4s are similar and support rubble pile models

    Morphological aspects of male and female hands

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    This is an electronic version of an article published in Annals of Human Biology, 1996, 23(6), 491-494. Annals of Human Biology is available online at informaworldTM http://www.informaworld.com/smpp/content~content=a739339013~db=all~order=pageThis journal article discusses a series of hand radiographs from Gwynedd, North Wales, which were assessed for frequencies in digital and metacarpal formulae between the genders

    Optical data of meteoritic nano-diamonds from far-ultraviolet to far-infrared wavelengths

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    We have used different spectroscopic techniques to obtain a consistent quantitative absorption spectrum of a sample of meteoritic nano-diamonds in the wavelength range from the vacuum ultraviolet (0.12 μ\mum) to the far infrared (100 μ\mum). The nano-diamonds have been isolated by a chemical treatment from the Allende meteorite (Braatz et al.2000). Electron energy loss spectroscopy (EELS) extends the optical measurements to higher energies and allows the derivation of the optical constants (n & k) by Kramers-Kronig analysis. The results can be used to restrain observations and to improve current models of the environment where the nano-diamonds are expected to have formed. We also show that the amount of nano-diamond which can be present in space is higher than previously estimated by Lewis et al. (1989).Comment: 11 pages, 7 figure

    Young people on the 'edge of care': perspectives regarding a residential family intervention programme using social pedagogic and systemic approaches- striving for 'humane practice'

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    Support approaches and interventions to keep families together are major goals in family welfare services. Different service models are used including some targeted at families where the assessment is part of family court pre-proceedings. Although outcomes of family interventions have been extensively researched, there is limited recent research regarding the subjective experiences of young people, their parents/carers and professionals who experience an intervention where they all live together for a short period and where mutually agreed goals and a family programme are co-created. This article presents findings from an exploratory qualitative study into a residential family learning project where families from an English inner-city local authority and professionals reside together for up to a week with engagement in intensive family work. Findings revealed mixed experiences of the intervention with a key theme being that a sense of time and space allowed the families to reflect and listen to each other’s perspectives leading to relationships improving and shifting. However, despite positive changes being made during the intervention sustaining these changes when returning home was often challenging. Findings, which are linked to the systemic idea of punctuation where families saw professionals differently and vice versa, had particular significance for families experiencing social and economic deprivation

    Changes in muscularity with growth and its relationship with other carcass traits in three terminal sire breeds of sheep

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    Data were available for 160 sheep (50 Suffolk males, 50 Suffolk females, 40 Texel males and 20 Charollais males). One fifth of animals within each breed and sex were slaughtered at each of 14, 18 or 22 weeks of age and two-fifths slaughtered at 26 weeks. After slaughter linear measurements were taken on the carcass. The left side of each carcass was then separated into eight joints and each joint dissected into lean, bone and fat. Five muscularity measures (three for the longissimus thoracis et lumborum (LTL) muscle, one for the hind leg and one for the whole carcass) and one for the shape of the LTL cross-section (depth : width) were calculated. With the exception of one measure for the LTL muscularity increased with growth. Rates of increase in most measures were higher in Texels that in each of the other breads, but were not different between the male and female Suffolks or between the Suffolk and Charollais lambs. Increase in most muscularity measures at 17 constant live weight were associated with increases in lean to bone ratio and carcass lean content. Associations with fat content were either non-significant or weak. Correlations between the three measures of muscularity for the LTL were high. Correlations between the whole carcass measure and those within different regions were moderate to high in the Texels but lower in the Suffolk and Charollais breeds. The same was true for correlations between the LTL measures and hind leg muscularity. If muscularity throughout the carcass is to be described effectively, measures in more than one region may be required, particularly in the Suffolk and Charollais breeds
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