3,156 research outputs found

    A semianalytical satellite theory for weak time-dependent perturbations

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    The modifications of the semianalytical satellite theory required to include these 'weak' time dependent perturbations are described. The new formulation results in additional terms in the short periodic variations but does not change the averaged equations of motion. Thus the m monthly terms are still included in the averaged equations of motion. This contrasts with the usual approach for the strongly time dependent perturbations in which the m monthly (or m daily, if tesseral harmonics are being considered) terms would be eliminated from the averaged equations of motion and included in the short periodics computation. Numerical test results for the GPS case obtained with a numerical averaging implementation of the new theory demonstrate the accuracy improvement

    Small Engine Component Technology (SECT)

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    A study of small gas turbine engines was conducted to identify high payoff technologies for year-2000 engines and to define companion technology plans. The study addressed engines in the 186 to 746 KW (250 to 1000 shp) or equivalent thrust range for rotorcraft, commuter (turboprop), cruise missile (turbojet), and APU applications. The results show that aggressive advancement of high payoff technologies can produce significant benefits, including reduced SFC, weight, and cost for year-2000 engines. Mission studies for these engines show potential fuel burn reductions of 22 to 71 percent. These engine benefits translate into reductions in rotorcraft and commuter aircraft direct operating costs (DOC) of 7 to 11 percent, and in APU-related DOCs of 37 to 47 percent. The study further shows that cruise missile range can be increased by as much as 200 percent (320 percent with slurry fuels) for a year-2000 missile-turbojet system compared to a current rocket-powered system. The high payoff technologies were identified and the benefits quantified. Based on this, technology plans were defined for each of the four engine applications as recommended guidelines for further NASA research and technology efforts to establish technological readiness for the year 2000

    Peran Mediasi Affective Commitment Pada Hubungan Procedural Justice, Perceived Organizational Support Dengan Employee Engagement

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    Organisasi yang memiliki karyawan yang engagement pada pekerjaan akan dapat meraih keunggulan kompetitif. Keadilan prosedural (procedural justice), persepsi atas dukungan yang diberikan organisasi (perceived organizational support) dan komitmen afektif (affective commitment) dapat sebagai variabel untuk membangun employee engagement.Penelitian ini dilakukan pada karyawan bagian produksi Perusahaan manufaktur di Surabaya. Penelitian ini bertujuan untuk mengetahui pengaruh procedural justice dan perceived organizational support terhadap employee engagement dengan affective commitment sebagai variabel mediasi. Penelitian ini menggunakan pendekatan kuantiatif. Sampel pada penelitian ini adalah karyawan tetap bagian produksi Perusahaan manufaktur di Surabaya sejumlah 182 sampel dengan menggunakan metode sensus. Teknik analisis yang digunakan dalam penelitian ini adalah teknik analisis Partial Least Square (PLS)Hasil pada penelitian ini menunjukan bahwa procedural justice dan perceived organizational support berpengaruh secara signifikan employee engagement dan affective commitment sebagai variabel mediasi karyawan bagian produksi Perusahaan manufaktur

    Usefulness of species traits in predicting range shifts

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    Information on species’ ecological traits might improve predictions of climate-driven range shifts. However, the usefulness of traits is usually assumed rather than quantified. We present a framework to identify the most informative traits, based on four key range-shift processes: (i) emigration of individuals or propagules away from the natal location, (ii) the distance a species can move, (iii) establishment of self-sustaining populations, and (iv) proliferation following establishment. We propose a framework that categorises traits according to their contribution to range-shift processes. We demonstrate how the framework enables the predictive value of traits to be evaluated empirically, how this categorisation can be used to better understand range shift processes, and illustrate how range shift estimates can be improved

    Moving Beyond Lip Service: The Clinical Reasoning Behind Practicing Strengths

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    Social work has a long tradition of advocating for practice from the strengths perspective. However, it is unclear whether schools are truly preparing students for strengths based practice or whether they are simply teaching them to use the vocabulary of strengths without the clinical reasoning skills to switch paradigms from deficits to strengths, moving beyond lip service to real strengths-based practice. To explore this issue, data from an exercise in an MSW course was explored using qualitative methodology. The findings support that in addition to using a strengths vocabulary, other components are necessary for true implementation of a strengths approach. First, the data revealed a strengths-oriented structural model of an ideal process of clinical reasoning for approaching a client situation. Second, the process includes recognizing client strengths, reflecting on them with the client, and encouraging repetition and reinforcement of the client’s positive attitudes and actions. Finally, true strengths based understanding requires moving from social worker in the role of expert to social worker engaged in collaborative empowerment practice. These findings have implications for social work practice and education

    Forecasting the global extent of invasion of the cereal pest Spodoptera frugiperda, the fall armyworm

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    This is the final version. Available on open access from Pensoft Publishers via the DOI in this recordData availability statement: Some distribution data from South America analysed during this study are included in the Supplementary Information files. This does not include data from Plantwise clinics in Bolivia, Honduras, Nicaragua and Peru, due to data sharing restrictions. Some other distribution data are available from CABI’s Plantwise programme but restrictions apply to the availability of these data, which were used under licence for the current study and so are not publicly available. Data may be available from the authors upon reasonable request and with permission of Plantwise. All other data used are publicly available from the referenced data sources.Fall armyworm, Spodoptera frugiperda, is a crop pest native to the Americas, which has invaded and spread throughout sub-Saharan Africa within two years. Recent estimates of 20-50% maize yield loss in Africa suggest severe impact on livelihoods. Fall armyworm is still infilling its potential range in Africa and could spread to other continents. In order to understand fall armyworm’s year-round, global, potential distribution, we used evidence of the effects of temperature and precipitation on fall armyworm life-history, combined with data on native and African distributions to construct Species Distribution Models (SDMs). We also investigated the strength of trade and transportation pathways that could carry fall armyworm beyond Africa. Up till now, fall armyworm has only invaded areas that have a climate similar to the native distribution, validating the use of climatic SDMs. The strongest climatic limits on fall armyworm’s year-round distribution are the coldest annual temperature and the amount of rain in the wet season. Much of sub-Saharan Africa can host year-round fall armyworm populations, but the likelihoods of colonising North Africa and seasonal migrations into Europe are hard to predict. South and Southeast Asia and Australia have climate conditions that would permit fall armyworm to invade. Current trade and transportation routes reveal Australia, China, India, Indonesia, Malaysia, Philippines and Thailand face high threat of fall armyworm invasions originating from Africa.Biotechnology and Biological Sciences Research Council (BBSRC)UK Department for International Development (DfID

    Is early center-based child care associated with tantrums and unmanageable behavior over time up to school entry?

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    Background. Existing research suggests that there is a relationship between greater exposure to center-based child care and child behavioral problems though the mechanism for the impact is unclear. However the measure used to document child care has usually been average hours, which may be particularly unreliable in the early months when fewer children are in center care. In addition individual trajectories for behavior difficulties have not been studied. Objective. The purpose of the current study was to examine whether the extent of exposure to center-based child care before two years predicted the trajectory of children’s difficult behavior (i.e., tantrums and unmanageable behavior) from 30 to 51 months controlling for child and maternal characteristics. Method. Data were drawn from UK-based Families, Children and Child Care (FCCC) study (n=1201). Individual growth models were fitted to test the relation between early center-based child care experiences and subsequent difficult behavior. Results. Children with more exposure to center-based care before two had less difficult behavior at 30 months, but more increase over time. Initial levels were predicted by higher difficult temperament and lower verbal ability. Higher difficult temperament and lower family socio-economic status predicted its change over time. Conclusion. Findings suggest that early exposure to center-based care before two years old is a risk factor for subsequent behavior problems especially when children have a longer period of exposure. A possible explanatory process is that child coping strategies to manage frustration are less well developed in a group context, especially when they lag behind in expressive language

    Estimating the Economic Value of Australian Stock Herding Dogs

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    This study aimed to estimate the value of the typical Australian herding dog in terms of predicted return on investment. This required an assessment of the costs associated with owning herding dogs and estimation of the work they typically perform. Data on a total of 4,027 dogs were acquired through The Farm Dog Survey which gathered information from 812 herding dog owners around Australia. The median cost involved in owning a herding dog was estimated to be a total of AU7,763overtheperiodofitsworkinglife.TheworkperformedbythedogthroughoutthistimewasestimatedtohaveamedianvalueofAU7,763 over the period of its working life. The work performed by the dog throughout this time was estimated to have a median value of AU40,000. So, herding dogs typically provided their owners with a 5.2-fold return on investment. When respondents were asked to nominate the maximal, one-off, veterinary expenditure they would consider to remedy an illness or injury for an especially valued dog, the median response was AU$1,001–2,000 which is not concordant with the dogs’ calculated median lifetime value. The current findings equip working dog owners with useful information to make financially appropriate expenditure decisions related to their working dogs. This is expected to increase farm profitability and improve welfare for farm dogs

    Valuable Behavioural Phenotypes in Australian Farm Dogs

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    This report presents findings regarding the ways to optimise the performance of livestock working dogs in Australia. The methods available to optimise dog performance include both environmental and genetic factors. The objectives of this study were to identify objective measures of desirable behavioural phenotypes in Australian livestock working dogs and explore genetic parameters of these \u27quality of working life\u27 traits within the Kelpie breed. The document reports on genotyping that reveals gene-behaviour associations and describes heritability estimates that underpin a database for potential estimated breeding value (EBV) calculations
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