8,750 research outputs found

    Some system considerations in configuring a digital flight control - navigation system

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    A trade study was conducted with the objective of providing a technical guideline for selection of the most appropriate computer technology for the automatic flight control system of a civil subsonic jet transport. The trade study considers aspects of using either an analog, incremental type special purpose computer or a general purpose computer to perform critical autopilot computation functions. It also considers aspects of integration of noncritical autopilot and autothrottle modes into the computer performing the critical autoland functions, as compared to the federation of the noncritical modes into either a separate computer or with a R-Nav computer. The study is accomplished by establishing the relative advantages and/or risks associated with each of the computer configurations

    From a Mirage to an Oasis: Narcissism, Perceived Creativity, and Creative Performance

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    We examine the link between narcissism and creativity at the individual, relational, and group levels of analysis. We find that narcissists are not necessarily more creative than others but they think they are, and they are adept at convincing others to agree with them. In the first study, narcissism was positively associated with self-rated creativity, despite the fact that blind coders saw no difference between the creative products offered by those low and high on narcissism. In a second study, more narcissistic individuals asked to pitch creative ideas to a target person were judged by the targets as being more creative than were less narcissistic individuals, in part because narcissists were more enthusiastic. Finally, in a study of group creativity, we find evidence of a curvilinear effect: having more narcissists is better for generating creative outcomes (but having too many provides diminishing returns)

    Persistence and the Random Bond Ising Model in Two Dimensions

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    We study the zero-temperature persistence phenomenon in the random bond ±J\pm J Ising model on a square lattice via extensive numerical simulations. We find strong evidence for ` blocking\rq regardless of the amount disorder present in the system. The fraction of spins which {\it never} flips displays interesting non-monotonic, double-humped behaviour as the concentration of ferromagnetic bonds pp is varied from zero to one. The peak is identified with the onset of the zero-temperature spin glass transition in the model. The residual persistence is found to decay algebraically and the persistence exponent θ(p)0.9\theta (p)\approx 0.9 over the range 0.1p0.90.1\le p\le 0.9. Our results are completely consistent with the result of Gandolfi, Newman and Stein for infinite systems that this model has ` mixed\rq behaviour, namely positive fractions of spins that flip finitely and infinitely often, respectively. [Gandolfi, Newman and Stein, Commun. Math. Phys. {\bf 214} 373, (2000).]Comment: 9 pages, 5 figure

    K(ππ)I=2K\to(\pi\pi)_{I=2} decays and twisted boundary conditions

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    We propose a new method to evaluate the Lellouch-L\"uscher factor which relates the ΔI=3/2\Delta I=3/2 KππK\to\pi\pi matrix elements computed on a finite lattice to the physical (infinite-volume) decay amplitudes. The method relies on the use of partially twisted boundary conditions, which allow the s-wave ππ\pi\pi phase shift to be computed as an almost continuous function of the centre-of-mass relative momentum and hence for its derivative to be evaluated. We successfully demonstrate the feasibility of the technique in an exploratory computation.Comment: 19 pages, 7 figure

    Hair radioactivity as a measure of exposure to radioisotopes

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    Since many radioisotopes accumulate in hair, this tropism was investigated by comparing the radioactivity of shaved with plucked hair collected from rats at various time intervals up to 24 hrs after intravenous injection of the ecologically important radioisotopes, iodine-131, manganese-54, strontium-85, and zinc-65. The plucked hair includes the hair follicles where biochemical transformations are taking place. The data indicate a slight surge of each radioisotpe into the hair immediately after injection, a variation of content of each radionuclide in the hair, and a greater accumulation of radioactivity in plucked than in shaved hair. These results have application not only to hair as a measure of exposure to radioisotopes, but also to tissue damage and repair at the hair follicle

    Evolutionary rates and gene dispensability associate with replication timing in the Archaeon Sulfolobus islandicus

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    In bacterial chromosomes, the position of a gene relative to the single origin of replication generally reflects its replication timing, how often it is expressed, and consequently, its rate of evolution. However, because some archaeal genomes contain multiple origins of replication, bias in gene dosage caused by delayed replication should be minimized and hence the substitution rate of genes should associate less with chromosome position. To test this hypothesis, six archaeal genomes from the genus Sulfolobus containing three origins of replication were selected, conserved orthologs were identified, and the evolutionary rates (dN and dS) of these orthologs were quantified. Ortholog families were grouped by their consensus position and designated by their proximity to one of the three origins (O1, O2, O3). Conserved orthologs were concentrated near the origins and most variation in genome content occurred distant from the origins. Linear regressions of both synonymous and nonsynonymous substitution rates on distance from replication origins were significantly positive, the rates being greatest in the region furthest from any of the origins and slowest among genes near the origins. Genes near O1 also evolved faster than those near O2 and O3, which suggest that this origin may fire later in the cell cycle. Increased evolutionary rates and gene dispensability are strongly associated with reduced gene expression caused in part by reduced gene dosage during the cell cycle. Therefore, in this genus of Archaea as well as in many Bacteria, evolutionary rates and variation in genome content associate with replication timing

    A dynamical and kinematical model of the Galactic stellar halo and possible implications for galaxy formation scenarios

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    We re-analyse the kinematics of the system of blue horizontal branch field (BHBF) stars in the Galactic halo (in particular the outer halo), fitting the kinematics with the model of radial and tangential velocity dispersions in the halo as a function of galactocentric distance r proposed by Sommer-Larsen, Flynn & Christensen (1994), using a much larger sample (almost 700) of BHBF stars. The basic result is that the character of the stellar halo velocity ellipsoid changes markedly from radial anisotropy at the sun to tangential anisotropy in the outer parts of the Galactic halo (r greater than approx 20 kpc). Specifically, the radial component of the stellar halo's velocity ellipsoid decreases fairly rapidly beyond the solar circle, from approx 140 +/- 10 km/s at the sun, to an asymptotic value of 89 +/- 19 km/s at large r. The rapid decrease in the radial velocity dispersion is matched by an increase in the tangential velocity dispersion, with increasing r. Our results may indicate that the Galaxy formed hierarchically (partly or fully) through merging of smaller subsystems - the 'bottom-up' galaxy formation scenario, which for quite a while has been favoured by most theorists and recently also has been given some observational credibility by HST observations of a potential group of small galaxies, at high redshift, possibly in the process of merging to a larger galaxy (Pascarelle et al 1996).Comment: Latex, 16 pages. 2 postscript figures. Submitted to the Astrophysical Journal. also available at http://astro.utu.fi/~cflynn/outerhalo.htm

    In situ aerosol measurements taken during the 2007 COPS field campaign at the Hornisgrinde ground site

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    Copyright @ 2011 Royal Meteorological Society.The Convective and Orographically-induced Precipitation Study (COPS) campaign was conducted during the summer of 2007. A suite of instruments housed at the top of the Hornisgrinde Mountain (1156 m) in the Black Forest region of south-west Germany provided datasets that allow an investigation into the physical, chemical and hygroscopic properties of the aerosol particles sampled during COPS. Organic mass loadings were found to dominate the aerosol composition for the majority of the project, exceeding 8 µg m−3 during a period of high pressure, high temperature, and low wind speed. The ratio of organic:sulphate sub-micron mass concentration exceeds 10:1 during the same time period. Back trajectories show air from this time-frame passing slowly over the local forest and not passing over any local anthropogenic sources. Occasional peaks in nitrate mass loadings were associated with changes in the typical wind direction from south-westerly to north-westerly where air had passed over the Stuttgart region. Size distribution data shows a dominant accumulation-mode when the measurement site was free from precipitation events. A sharp increase in ultrafine particle number concentration was seen during most days commencing around noon. The apparent growth of these particles is associated with an increase in organic mass loading, suggesting condensational growth. For the most part, with the exception of the high pressure period, the aerosol properties recorded during COPS were comparable to previous studies of continental aerosol properties.NER

    What do people value when they provide unpaid care for an older person? A meta-ethnography with interview follow-up

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    Government policies to shift care into the community and demographic changes mean that unpaid (informal) carers will increasingly be relied on to deliver care, particularly to older people. As a result, careful consideration needs to be given to informal care in economic evaluations. Current methods for economic evaluations may neglect important aspects of informal care. This paper reports the development of a simple measure of the caring experience for use in economic evaluations. A meta-ethnography was used to reduce qualitative research to six conceptual attributes of caring. Sixteen semi-structured interviews were then conducted with carers of older people, to check the attributes and develop them into the measure. Six attributes of the caring experience comprise the final measure: getting on, organisational assistance, social support, activities, control, and fulfilment. The final measure (the Carer Experience Scale) focuses on the process of providing care, rather than health outcomes from caring. Arguably this provides a more direct assessment of carers' welfare. Following work to test and scale the measure, it may offer a promising way of incorporating the impact on carers in economic evaluations. © 2008 Elsevier Ltd. All rights reserved
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