22,347 research outputs found

    Microclimate variations between semienclosed and open sections of a marathon route

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    Spread of Infectious Diseases with a Latent Period

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    Infectious diseases spread through human networks. Susceptible-Infected-Removed (SIR) model is one of the epidemic models to describe infection dynamics on a complex network connecting individuals. In the metapopulation SIR model, each node represents a population (group) which has many individuals. In this paper, we propose a modified metapopulation SIR model in which a latent period is taken into account. We call it SIIR model. We divide the infection period into two stages: an infected stage, which is the same as the previous model, and a seriously ill stage, in which individuals are infected and cannot move to the other populations. The two infectious stages in our modified metapopulation SIR model produce a discontinuous final size distribution. Individuals in the infected stage spread the disease like individuals in the seriously ill stage and never recover directly, which makes an effective recovery rate smaller than the given recovery rate.Comment: 6 pages, 3 figure

    Impact of crop varieties on household food security in Haor areas of Bangladesh

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    The purpose of the study was to identify the crop varieties in the Haor area of Netrokona district to minimize the food vulnerability situation during food crisis. The study was conducted in four selected villages of Madan and Khaliajuri Upazilas under the Netrokona district. Data were collected from randomly selected 400 farmers from the study area in the year 2011. The findings of the study revealed that farmers usually cultivate only three HYV boro rice varieties (BR 19, BRRI dhan 28 and BRRI dhan 29) in the Haor area under study. In aman season farmers mostly cultivate local varieties and they get minimum yield. Only few vegetables found to cultivate by the farmers in Haor area. The vegetables are: onion, garlic, chilli, bottle gourd, sweet gourd, ladys finger and tomato. Among these onion, garlic and chilli are mostly cultivated. Many farmers reported that during the flood they had to face serious problems in respect of communication, diseases, increased price of different commodities, and lack of adequate government safety net programs/relief. Farmers lack of flood preparedness has been observed while some farmers remained uncared about the occurrence of flood and consequently they did not take any preparedness for flood. DOI: http://dx.doi.org/10.3329/ijarit.v3i2.17812 Int. J. Agril. Res. Innov. & Tech. 3 (2): 7-11, December, 201

    Hysterosalpingographic Findings in Patients with Infertility in South Eastern Nigeria

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    Hysterosalpingography (HSG) is still an integral part of gynecological evaluation of infertile couple and its value has not been underestimated in modern gynecological practice, especially in developing countries.The study aims to evaluate the findings at HSG in patients presenting with infertility at the Ebonyi State University Teaching Hospital,Abakaliki, Southeastern Nigeria. A retrospective analysis of 100 consecutive HSG results of patients presenting with infertility was done between January 2005-April 2008. Their clinical records and radiological findings were analyzed for demographic data, and cervical, uterine and tubal, pathology.The commonest age group was between 25 -34 years. Sixty-five percent presented with secondary infertility while 35% presented with secondary infertility. Hysterosalpingographic findings were abnormal in 80% of patients(primary infertility 20% and secondary infertility 60%). Bilateral tubal blockage and bilateral fimbrial adhesion were the commonest tubal factor abnormalities while intracavitary mass impression and cervical synechia were the commonest findings for uterine and cervical factor abnormalities respectively. Tubal blockage and tubal factor infertilityare still common among infertile couples. This may probably be due to chronic pelvic inflammatory disease or pelvic infection following sexually transmitted infections, mismanaged pregnancies and septic abortions, as most of the patients presented with secondary infertility. Measures to prevent the occurrence of these infections are highlighted.Keywords: Hysterosalpingography, Infertility, Abakaliki, Southeastern Nigeria

    Negative frequency-dependent selection is intensified at higher population densities in protist populations

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    This is the final version of the article. Available from the Royal Society via the DOI in this record.Natural populations of free-living protists often exhibit high-levels of intraspecific diversity, yet this is puzzling as classic evolutionary theory predicts dominance by genotypes with high fitness, particularly in large populations where selection is efficient. Here, we test whether negative frequency-dependent selection (NFDS) plays a role in the maintenance of diversity in the marine flagellate Oxyrrhis marina using competition experiments between multiple pairs of strains. We observed strain-specific responses to frequency and density, but an overall signature of NFDS that was intensified at higher population densities. Because our strains were not selected a priori on the basis of particular traits expected to exhibit NFDS, these data represent a relatively unbiased estimate of the role for NFDS in maintaining diversity in protist populations. These findings could help to explain how bloom-forming plankton, which periodically achieve exceptionally high population densities, maintain substantial intraspecific diversity.E.J.A.M. was supported by a NERC research studentship (NE/H025472/2) as part of the UK Ocean Acidification Research Programme

    Goodwill Hunting:Why and When Ultimate Controlling Owners Affect Their Firms' Corporate Social Responsibility Performance

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    Researchers have long been interested in how owners affect firms’ corporate social responsibility (CSR) performance. However, owners face diverging ethical preferences between funding and potentially benefiting from their firms’ CSR performance. To better understand owners’ influence on firms’ CSR performance, we focus on ultimate controlling owners with the highest control rights over their firms. We theorize that ultimate controlling owners with more control rights have stronger motivations and greater decision-making power to promote firms’ CSR performance to demonstrate that they are responsible owners and gain legitimacy and goodwill from their stakeholders. Moreover, we explore how this positive relationship is strengthened when ultimate controlling owners and their firms share similar corporate names and receive increased financial analyst coverage, as these conditions increase the likelihood of gaining legitimacy and goodwill through their firms’ improved CSR performance. We test our theory using a sample of 852 publicly listed Chinese firms from 2008 to 2017. Our findings support our theoretical predictions and contribute to a more nuanced understanding of how differences in ownership structure and owner type associated with ultimate controlling owners shape their motives and power to affect CSR performance in their firms

    The impact of environmental and human factors on urban heat and microclimate variability

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    Urbanization is known to cause noticeable changes in the properties of local climate. Studies have shown that urban areas, compared to rural areas with less artificial surfaces, register higher local temperatures as a result of Urban Heat Islands (UHIs). Hong Kong is one of the most densely populated cities in the world and a high proportion of its population residing in densely built high-rise buildings are experiencing some degrees of thermal discomfort. This study selected Mong Kok and Causeway Bay, two typical urban communities in Hong Kong, to gather evidence of microclimate variation and sources of thermal discomfort. UHIs were estimated from 58 logging sensors placed at strategic locations to take temperature and humidity measurements over 17 consecutive days each in the summer/hot and winter/cool periods. By employing geographic information and global positioning systems, these measurements were geocoded and plotted over the built landscape to convey microclimate variation. The empirical data were further aligned with distinct environmental settings to associate possible factors contributing to UHIs. This study established the existence and extent of microclimate variation of UHI within urban communities of different environmental configuration and functional uses. The findings provided essential groundwork for further studies of UHI effects to inform sources of local thermal discomfort and better planning design to safeguard environmental health in public areas.postprin

    Gauge fields and infinite chains of dualities

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    We show that the particle states of Maxwell's theory, in DD dimensions, can be represented in an infinite number of ways by using different gauge fields. Using this result we formulate the dynamics in terms of an infinite set of duality relations which are first order in space-time derivatives. We derive a similar result for the three form in eleven dimensions where such a possibility was first observed in the context of E11. We also give an action formulation for some of the gauge fields. In this paper we give a pedagogical account of the Lorentz and gauge covariant formulation of the irreducible representations of the Poincar\'e group, used previously in higher spin theories, as this plays a key role in our constructions. It is clear that our results can be generalised to any particle.Comment: 37 page

    Investigation of the Magnetic Response of a Nanocrystalline High-Frequency Magnetic Link With Multi-Input Excitations

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    © 2019 IEEE. With the technological advancement of magnetic materials and semiconductor devices, the use of high-frequency magnetic link made of high-saturation induction and low specific core loss nanocrystalline alloy has been gaining popularity to replace the common dc link or ac link specially in integrating multiple renewable sources to the grid. The magnetic integration of multiple renewable sources through a common magnetic link has a number of advantages including galvanic isolation compared with the common dc or ac link. However, the magnetic response of the common magnetic link under multi-input excitations highly affects the energy conversion efficiency. To the best of the authors' knowledge, the magnetic response of an advanced magnetic-material-based magnetic link under multi-input excitations has not been well investigated in the literature. In this paper, a systematic investigation is carried out to interconnect multiple sources through a common magnetic link. The magnetic response and the procedure used in the investigation are also presented and discussed in this paper

    Dynamic Label Graph Matching for Unsupervised Video Re-identification

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    © 2017 IEEE. Label estimation is an important component in an unsupervised person re-identification (re-ID) system. This paper focuses on cross-camera label estimation, which can be subsequently used in feature learning to learn robust re-ID models. Specifically, we propose to construct a graph for samples in each camera, and then graph matching scheme is introduced for cross-camera labeling association. While labels directly output from existing graph matching methods may be noisy and inaccurate due to significant cross-camera variations, this paper propose a dynamic graph matching (DGM) method. DGM iteratively updates the image graph and the label estimation process by learning a better feature space with intermediate estimated labels. DGM is advantageous in two aspects: 1) the accuracy of estimated labels is improved significantly with the iterations; 2) DGM is robust to noisy initial training data. Extensive experiments conducted on three benchmarks including the large-scale MARS dataset show that DGM yields competitive performance to fully supervised baselines, and outperforms competing unsupervised learning methods.
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