4,297 research outputs found

    Pressure Treated Wood

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    Discusses chemical treatments to increase wood's fire resistance and protect it from rot and termites

    Attitudes to telecare among older people, professional care workers and informal carers: a preventative strategy or crisis management?

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    This paper reports findings from an attitudinal survey towards telecare that emerged from twenty-two focus groups comprising ninety-two older people, fifty-five professional stakeholders and thirty-nine carers. These were convened in three different regions of England as a precursor to telecare service development. The results from this study suggest that informants’ views were shaped by prior knowledge of conventional health and social care delivery in their locality and the implication is that expectations and requirements in respect of telecare services in general are likely to be informed by wider perceptions about the extent to which community care should operate as a preventative strategy or as a mechanism for crisis management

    Damped Lyman alpha systems and disk galaxies: number density, column density distribution and gas density

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    We present a comparison between the observed properties of damped Lyman alpha systems (DLAs) and the predictions of simple models for the evolution of present day disk galaxies, including both low and high surface brightness galaxies. We focus in particular on the number density, column density distribution and gas density of DLAs, which have now been measured in relatively large samples of absorbers. From the comparison we estimate the contribution of present day disk galaxies to the population of DLAs, and how it varies with redshift. Based on the differences between the models and the observations, we also speculate on the nature of the fraction of DLAs which apparently do not arise in disk galaxies.Comment: 11 pages, 10 figures, accepted in MNRA

    Carbureting conditions characteristics of aircraft engines

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    Tests were conducted at the altitude laboratory erected at the Bureau of Standards for the National Advisory Committee for Aeronautics to determine the changes in engine performance with changes in atmospheric temperature and pressure at various levels above the earth's surface, with special reference to (a) the variables affecting the functioning of the carburetor and (b) the changes in performance resulting from variables in the carburetor itself. This report constitutes a concise statement of the difficulties to be encountered in this branch of carburetion

    Sea turtle nesting in the Ten Thousand Islands of Florida

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    Loggerhead sea turtles (Caretta caretta) nest in numerous substrate and beach types within the Ten Thousand Islands (TTl) of southwest Florida. Nesting beach selection was analyzed on 12 islands within this archipelago. Numerous physical characteristics were recorded to identify the relatedness of these variables and determine their importance for nesting beach selection in C. caretta. These variables were chosen after evaluating the islands, conducting literature searches and soliciting personal communications. Along transects, data were collected, on the following: height of canopy, beach width, overall slope (beach slope and slope of offshore approach) and sand samples analyzed for pH, percentage of water, percentage of organic content, percentage of carbonate and particle size (8 size classes). Data on ordinal aspect of beaches and beach length were also recorded and included in the analysis. All of the variables were analyzed by tree regression, incorporating the nesting data into the analysis. In the TTl, loggerheads appear to prefer wider beaches (p< 0.001; R2 = 0.56) that inherently have less slope, and secondarily, wider beaches that have low amounts of carbonate (p< O.00 1). In addition, C. caretta favors nest sites within or in close proximity to the supra-littoral vegetation zone of beaches in the TTl (p< 0.001). (86 page document

    Survival and Growth of American Alligator (Alligator mississippiensis) hatchlings after artificial incubation and repatriation

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    Hatchling American Alligators (Alligator mississippiensis) produced from artificially incubated wild eggs were returned to their natal areas (repatriated). We compared artificially incubated and repatriated hatchlings released within and outside the maternal alligator’s home range with naturally incubated hatchlings captured and released within the maternal alligator’s home range on Lake Apopka, Lake Griffin, and Orange Lake in Florida. We used probability of recapture and total length at approximately nine months after hatching as indices of survival and growth rates. Artificially incubated hatchlings released outside of the maternal alligator’s home range had lower recapture probabilities than either naturally incubated hatchlings or artificially incubated hatchlings released near the original nest site. Recapture probabilities of other treatments did not differ significantly. Artificially incubated hatchlings were approximately 6% shorter than naturally incubated hatchlings at approximately nine months after hatching. We concluded that repatriation of hatchlings probably would not have long-term effects on populations because of the resiliency of alligator populations to alterations of early age-class survival and growth rates of the magnitude that we observed. Repatriation of hatchlings may be an economical alternative to repatriation of older juveniles for population restoration. However, the location of release may affect subsequent survival and growth

    Sewing sound quantum flesh onto classical bones

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    Semiclassical transformation theory implies an integral representation for stationary-state wave functions ψm(q)\psi_m(q) in terms of angle-action variables (Ξ,J\theta,J). It is a particular solution of Schr\"{o}dinger's time-independent equation when terms of order ℏ2\hbar^2 and higher are omitted, but the pre-exponential factor A(q,Ξ)A(q,\theta) in the integrand of this integral representation does not possess the correct dependence on qq. The origin of the problem is identified: the standard unitarity condition invoked in semiclassical transformation theory does not fix adequately in A(q,Ξ)A(q,\theta) a factor which is a function of the action JJ written in terms of qq and Ξ\theta. A prescription for an improved choice of this factor, based on succesfully reproducing the leading behaviour of wave functions in the vicinity of potential minima, is outlined. Exact evaluation of the modified integral representation via the Residue Theorem is possible. It yields wave functions which are not, in general, orthogonal. However, closed-form results obtained after Gram-Schmidt orthogonalization bear a striking resemblance to the exact analytical expressions for the stationary-state wave functions of the various potential models considered (namely, a P\"{o}schl-Teller oscillator and the Morse oscillator).Comment: RevTeX4, 6 page

    Formation of Dark Matter Haloes in a Homogeneous Dark Energy Universe

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    Several independent cosmological tests have shown evidences that the energy density of the Universe is dominated by a dark energy component, which cause the present accelerated expansion. The large scale structure formation can be used to probe dark energy models, and the mass function of dark matter haloes is one of the best statistical tools to perform this study. We present here a statistical analysis of mass functions of galaxies under a homogeneous dark energy model, proposed in the work of Percival (2005), using an observational flux-limited X-ray cluster survey, and CMB data from WMAP. We compare, in our analysis, the standard Press-Schechter (PS) approach (where a Gaussian distribution is used to describe the primordial density fluctuation field of the mass function), and the PL (Power Law) mass function (where we apply a nonextensive q-statistical distribution to the primordial density field). We conclude that the PS mass function cannot explain at the same time the X-ray and the CMB data (even at 99% confidence level), and the PS best fit dark energy equation of state parameter is ω=−0.58\omega=-0.58, which is distant from the cosmological constant case. The PL mass function provides better fits to the HIFLUGCS X-ray galaxy data and the CMB data; we also note that the ω\omega parameter is very sensible to modifications in the PL free parameter, qq, suggesting that the PL mass function could be a powerful tool to constrain dark energy models.Comment: 4 pages, 2 figures, Latex. Accepted for publication in the International Journal of Modern Physics D (IJMPD)

    The Open Cluster Distance Scale: A New Empirical Approach

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    We present new BVRI photometry for a sample of 54 local G and K stars with accurate Hipparcos parallaxes in the metallicity range -0.4 < [Fe/H] < +0.3. We use this sample to develop a completely model-independent main sequence (MS) fitting method which we apply to 4 open clusters - the Hyades, Praesepe, the Pleiades and NGC 2516 - which all have direct Hipparcos parallax distance determinations. Comparison of our MS-fitting results with distances derived from Hipparcos parallaxes enables us to explore whether the discrepancy between the Hipparcos distance scale and other MS-fitting methods found for some clusters is a consequence of model assumptions. We find good agreement between our results and the Hipparcos ones for the Hyades and Praesepe. For the Pleiades and NGC 2516, when adopting the solar abundance determined from spectroscopy, we find significant disagreement at a level similar to that found by other MS-fitting studies. However, the colour-colour relationship for both these clusters suggests that their metallicity is significantly subsolar. Since the MS-fitting method relies on matching the cluster colours to a template MS, we argue that, when applying this method, the appropriate metallicity to adopt is the photometric subsolar one, not the solar abundance indicated by spectroscopy. Adopting photometric metallicities for all 4 clusters, we find complete agreement with the Hipparcos results and hence we conclude that the mismatch between the spectroscopic and photometric abundances for the Pleiades and NGC 2516 is responsible for the discrepancies in distance estimates found by previous studies. The origin of this mismatch in abundance scales remains an unsolved problem and some possible causes are discussed
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