4,452 research outputs found

    Atomic density of an harmonically trapped ideal gas near Bose-Einstein transition temperature

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    We have studied the atomic density of a cloud confined in an isotropic harmonic trap at the vicinity of the Bose-Einstein transition temperature. We show that, for a non-interacting gas and near this temperature, the ground-state density has the same order of magnitude as the excited states density at the centre of the trap. This holds in a range of temperatures where the ground-state population is negligible compared to the total atom number. We compare the exact calculations, available in a harmonic trap, to semi-classical approximations. We show that these latter should include the ground-state contribution to be accurate.

    Estimation of Genetic Parameters for Preweaning Growth Traits of Crossbred Cattle.

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    Data from a long-term rotational crossbreeding study involving Angus, Brahman, Charolais and Hereford cattle were analyzed to evaluate the importance of maternal effects on birth weight (BWT), weaning weight (WWT) and preweaning average daily gain (ADG) and, to estimate genetic parameters. Six different animal models were fitted for each trait, ranging from a single additive to a maternal animal model allowing for both genetic and environmental maternal effects and a genetic covariance between direct and maternal additive effects. Genetic effects were obtained using a maternal animal model allowing for a maternal additive effect and a direct-maternal additive covariance (Model 4). All analyses were carried out using MTDFREML. Maternal permanent environmental variance were not important, while maternal additive (MGE) and the direct-maternal (co)variances were important for all traits. Ignoring MGE resulted in overestimates of \sigma \sbsp{\rm A}{2} and h\sbsp{\rm A}{2}. Direct heritability estimates from Model 4 were.35±\pm.05,.55±\pm.07 and.57±\pm.08 for BWT, WWT and ADG, respectively. For the MGE, the corresponding heritabilities were.14±\pm.02,.25±\pm.04 and.30±\pm.04. The direct-maternal genetic correlations were.26±\pm.14, −-.36±\pm.09 and −-.49±\pm.08 for BWT, WWT and ADG, respectively. Charolais had the greatest positive direct additive genetic influences on preweaning growth traits and had the largest positive maternal additive genetic influence on WWT, compared to the Hereford breed. The Brahman had positive direct additive genetic influences for BWT and had negative direct additive influences for ADG, compared to the Hereford breed. Angus had negative direct additive genetic effects and had positive maternal additive genetic effects on preweaning growth traits, compared to the Hereford. Brahman was the only breed having a statistically significant maternal additive effect on BWT compared to Hereford. All breeds exhibited positive maternal additive influences on WWT and ADG over Hereford. All direct heterotic effects were positive, except for Angus-Charolais for BWT. Crossbred calves involving the Brahman were the most productive. Birth weight was not influenced by maternal heterosis, except for Charolais-Hereford maternal heterotic effect. Effects involving the Hereford were the only positive and significant maternal heterotic effects on WWT and ADG

    Proper Incentives for Proper IT Security Management – A System Dynamics Approach

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    Abstract \ It has been known for many years that security failures are caused at least as often by bad incentives as by bad design. However, the regulatory correction of bad incentives is not easy in practice and it is still lacking. In the meantime, system dynamics models of security systems can improve the situation by increasing the awareness that misaligned incentives can backfire as long-term consequences of security failures hit back the principal. We illustrate our argument using system archetypes and concept simulation models revealing the impact of two different security strategies, viz. misaligned incentives (the customer having the burden of proof in case of alleged fraud) vs the bank having the burden of proof. From this we argue that online system dynamics could be used in eGovernment to educate principals and the public. Also, legal measures could become more effective when supported with forensic evidence from simulation models.

    From Sensor to Observation Web with Environmental Enablers in the Future Internet

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    This paper outlines the grand challenges in global sustainability research and the objectives of the FP7 Future Internet PPP program within the Digital Agenda for Europe. Large user communities are generating significant amounts of valuable environmental observations at local and regional scales using the devices and services of the Future Internet. These communities’ environmental observations represent a wealth of information which is currently hardly used or used only in isolation and therefore in need of integration with other information sources. Indeed, this very integration will lead to a paradigm shift from a mere Sensor Web to an Observation Web with semantically enriched content emanating from sensors, environmental simulations and citizens. The paper also describes the research challenges to realize the Observation Web and the associated environmental enablers for the Future Internet. Such an environmental enabler could for instance be an electronic sensing device, a web-service application, or even a social networking group affording or facilitating the capability of the Future Internet applications to consume, produce, and use environmental observations in cross-domain applications. The term ?envirofied? Future Internet is coined to describe this overall target that forms a cornerstone of work in the Environmental Usage Area within the Future Internet PPP program. Relevant trends described in the paper are the usage of ubiquitous sensors (anywhere), the provision and generation of information by citizens, and the convergence of real and virtual realities to convey understanding of environmental observations. The paper addresses the technical challenges in the Environmental Usage Area and the need for designing multi-style service oriented architecture. Key topics are the mapping of requirements to capabilities, providing scalability and robustness with implementing context aware information retrieval. Another essential research topic is handling data fusion and model based computation, and the related propagation of information uncertainty. Approaches to security, standardization and harmonization, all essential for sustainable solutions, are summarized from the perspective of the Environmental Usage Area. The paper concludes with an overview of emerging, high impact applications in the environmental areas concerning land ecosystems (biodiversity), air quality (atmospheric conditions) and water ecosystems (marine asset management)

    IceCube3--a new window on the Universe

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    This paper gives an overview of the scientific goals of IceCube with an emphasis on the importance of atmospheric neutrinos. Status and schedule for completing the detector are presented.Comment: 13 pages, 6 figures, to appear in A.I.P. Conf. Proceedings, 3rd Latin American School on Cosmic Rays, Arequipa, Peru, September, 200

    Cardiovascular risk factors and determinants of clinical outcomes in type 2 diabetic patients at a tertiary-care centre

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    Background: The prevalence of type 2 diabetes mellitus (T2DM) is growing rapidly worldwide. The global burden of T2DM in 2013 was 382 million and projected to 592 million by 2035, accounting for 7.8% of the adult population. The objective of this study was to record treatments, risk factor control, determinants of glycaemic control and cardiovascular outcomes in type 2 diabetes (T2DM).Methods: We included adult T2DM patients and followed up for 6 months. Patients were categorised into good (HbA1c 8.5%). We used multiple logistic regression to identify determinants of glycaemic control and outcomes.Results: We recruited 785 patients with a mean age of 55.43 (±11.1) years, and 43.8% were women. At baseline, patients with poor control (45%) were younger and from lower socioeconomic strata (73.5%). At 6 months, the American Diabetes Association (ADA) targets of HbA1c was met only in 27.52%, systolic blood pressure (SBP) in 81.47% and low density lipoprotein (LDL) cholesterol in 48.86% patients. Patients with sedentary or low physical activity (Odds ratio 11.51, 95% confidence interval 3.48, 37.98; p<0.001) and with diabetes for a longer duration (OR 1.14 [1.07-1.22], p<0.001) were more likely to be in poor glucose control. Patients having sedentary or low physical activity (OR 6.66 [1.730-25.63] p = 0.006) and higher LDL cholesterol (OR 1.04 [1.01-1.07], p = 0.008) were more likely to get microvascular complications.Conclusions: Management of modifiable risk factors and early control of hyperglycaemia should be given more importance

    Sensitivity Analysis of Various Geometries of PCD and Cemented Tungsten Carbide Cutting Tools during the Milling of GFRP Composite

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    Although much research has been carried out in the field of the milling of GFRP (Glass Fibre Reinforced Polymer) composites, the complexity of the process is such that it is still not mastered in many industrial cases. The current work is aimed at studying the influence of three different geometries of PCD (PolyCrystalline Diamond) and cemented tungsten carbide cutting tools during the up-milling of GFRP composites at fixed cutting conditions (vc = 502 m/min and vf = 420 mm/min). Delamination, cutting forces and tool wear are compared at the fresh and worn states, and the correlation between the lifespan and the cost of the cutting tool is analysed. The main wearing phase of the tools was performed under the conditions of production in the facilities of a company (Sobelcomp, Loncin, Belgium). The results indicate that the PCD tool with the straight edge, inclined peripheral tooth shape produces the smallest total cutting force and less delamination (shortest and lowest number of delaminated fibres) at both fresh and worn states. Moreover, the grinding ability of PCD makes the cutting tool cost per part lower than for cemented carbide. The PCD tool is therefore the best option to mill GFRP parts
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