883 research outputs found

    A multimedia data visualization based on Ad Hoc communication networks and its application to disaster management

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    After massive earthquakes and other large-scale disasters, existing communication infrastructure may become unavailable and, therefore, it can be quite difficult for relief organizations to fully grasp the impact of the disaster on the affected region. Consequently, this will be the cause of delays to offer the strategic assistance, and to provide water and food, etc. In order to solve the problem of re-establishing communication infrastructure to allow for information gathering, we developed an ad hoc mobile communications network for disaster-struck areas using ZigBee. As the communication speed of ZigBee is low, we propose a problem-specific image compression method for the multimedia data visualization. By using the proposed method combined with GPS information, it is possible to quickly grasp the damage situation in the region. Through our communication experiments in Tsukuba City, Japan we confirm the effectiveness of our system as a disaster information gathering and management system

    Resource Management of Mobile Communication System

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    To ensure good traffic handling, channel allocation is one of the important mobile communication resources for quality of service. Usually, three types of channel allocations are widely used: fixed channel allocation, borrowing radio channels from surrounding calls and dynamic channel allocations. In this paper instead conventional channel allocation schemes, we used call admission control (CAC) scheme to combat forced termination (FT). The analytical model of traffic handling in mobile cellular network is implemented by Markov chain; hence the profile of call blocking probability of newly originating call and FT is shown against the call arrival rate and the number of channels. Finally the impact of fading parameters of wireless channel on FT is also analyzed under Rayleigh fading case

    On Testing Dependence between Time to Failure and Cause of Failure when Causes of Failure Are Missing

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    The hypothesis of independence between the failure time and the cause of failure is studied by using the conditional probabilities of failure due to a specific cause given that there is no failure up to certain fixed time. In practice, there are situations when the failure times are available for all units but the causes of failures might be missing for some units. We propose tests based on U-statistics to test for independence of the failure time and the cause of failure in the competing risks model when all the causes of failure cannot be observed. The asymptotic distribution is normal in each case. Simulation studies look at power comparisons for the proposed tests for two families of distributions. The one-sided and the two-sided tests based on Kendall type statistic perform exceedingly well in detecting departures from independence

    Reconfigurable metamaterial structure for 5G beam tilting antenna applications

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    In this paper, we propose a metamaterial (MTM) structure with a reconfigurable property designed to operate at the millimetre-wave (mm-wave) spectrum. Four switches are used to achieve the reconfigurable property of the MTM with two configurations. These two configurations exhibit different refractive indices, which used to guide the radiation beam of the antenna to the desired direction. The proposed planar dipole antenna operates at the 5th generation (5G) band of 28 GHz. The electromagnetic (EM) rays of the proposed antenna pass through different MTM configurations with different phases, subsequently results in the tilting of the radiation beam toward MTM configuration of high refractive index. Simulated and measured results of the proposed antenna loaded by MTM demonstrate that the radiation beam is tilted by angles of +34° and −31° in the E-plane depending on the arrangement of two MTM configurations onto the antenna substrate. Furthermore, the gain is improved by 1.7 and 1.5 dB for positive and negative tilting angles, respectively. The reflection coefficients of the antenna with MTM are kept below −10 dB at 28 GHz

    Effect of n-hexane extract of Nigella sativa on gentamicin-induced nephrotoxicity in rats

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    The present study investigated whether the administration of the n-hexane extract of the Nigella sativa Linn. (kalajira) ameliorates gentamicin-induced nephrotoxicity in rats. Gentamicin (100 mg/kg/day for 7 days) was administered and nephrotoxicity was evaluated biochemically (significantly decreased reduced glutathione in renal cortex and significantly increased serum creatinine and serum urea) and histologically (moderate degree of proximal tubular damage). The n-hexane extract of N. sativa (5 mL/kg/day) was administered as pre-, post- and concomitant treatment for 7 days in the nephrotoxic rats. Statistically significant amelioration in all the biochemical parameters supported by significantly improved renal cortical histology was observed in the n-hexane extract of N. sativa treated nephrotoxic rats, which was more evident in the post-treatment group than the pre-treatment and the concomitantly-treated group. It is suggested that some ingredients contained in the n-hexane extract of N. sativa effected in ameliorating the signs of nephrotoxicity and that the specific active principle of the n-hexane extract of N. sativa responsible for this amelioration if obtained, would be more useful

    Influence of argon pollution on the weld surface morphology

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    In this paper the surfaces of butt welded joints in steel tubes were analyzed using an optical 3D measurement system to determine the morphology and topographic parameters. It was established that pollution of the argon shield gas with oxygen did not influence the width of the heat-affected zone. However, the composition of the shield gas significantly influenced the surface asymmetry, Ssk, and its inclination Sku. The measurement of these parameters enabled the selection of a higher quality surface, which was visually proven by the reduction in discoloration of the surface of the weld joint. High quality surfaces eliminate a potential habitat for bacteria and a future source of corrosion as well as providing less resistance to fluid flow

    Psychometric properties of three online-related addictive behavior instruments among Bangladeshi school-going adolescents

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    Background: Due to the ease of access to the internet in modern society users have become more prone to experiencing addictive behaviors online. The present study aimed to develop and investigate the psychometric properties of the Bangla Internet Gaming Disorder Scale–Short-Form (IGDS9-SF), Gaming Disorder Test (GDT), and Bergen Social Media Addiction Scale (BSMAS) due to a lack of existing sound psychometric tools in Bangladesh. Methods: A cross-sectional paper-and-pencil survey was carried out among 428 school-aged adolescents who were active gamers (90.89% males; Meanage: 16.13±1.85 years; age range: 10–19 years). Participants were recruited using convenience sampling across four selected schools in Dhaka City, Bangladesh. Data collected included sociodemographic information, frequency of internet use and gaming behaviors, psychological states (i.e., Patient Health Questionnaire [PHQ-9], Generalized Anxiety Disorder [GAD-7]), disordered gaming and social media use (i.e., IGDS9-SF, GDT, and BSMAS). Psychometric testing was conducted to examine the validity and reliability levels of the Bangla IGDS9-SF, GDT, and BSMAS. Results: The newly adapted Bangla IGDS9-SF, GDT, and BSMAS exhibited adequate levels of internal consistency. All total scores were significantly correlated with depression, anxiety, frequencies of internet use/online activities and gaming, supporting criterion and convergent validity. CFA indicated excellent construct validity as all instruments had a good fit to the data. Conclusions: The findings suggest that the Bangla IGDS9-SF, GDT, and BSMAS are sound psychometric instruments due to their satisfactory psychometric properties including internal consistency, criterion validity, convergent validity, and construct validity

    Recent Developments in Understanding Two-dimensional Turbulence and the Nastrom-Gage Spectrum

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    Two-dimensional turbulence appears to be a more formidable problem than three-dimensional turbulence despite the numerical advantage of working with one less dimension. In the present paper we review recent numerical investigations of the phenomenology of two-dimensional turbulence as well as recent theoretical breakthroughs by various leading researchers. We also review efforts to reconcile the observed energy spectrum of the atmosphere (the spectrum) with the predictions of two-dimensional turbulence and quasi-geostrophic turbulence.Comment: Invited review; accepted by J. Low Temp. Phys.; Proceedings for Warwick Turbulence Symposium Workshop on Universal features in turbulence: from quantum to cosmological scales, 200

    Fifteen new risk loci for coronary artery disease highlight arterial-wall-specific mechanisms

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    Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Although 58 genomic regions have been associated with CAD thus far, most of the heritability is unexplained, indicating that additional susceptibility loci await identification. An efficient discovery strategy may be larger-scale evaluation of promising associations suggested by genome-wide association studies (GWAS). Hence, we genotyped 56,309 participants using a targeted gene array derived from earlier GWAS results and performed meta-analysis of results with 194,427 participants previously genotyped, totaling 88,192 CAD cases and 162,544 controls. We identified 25 new SNP-CAD associations (P < 5 × 10(-8), in fixed-effects meta-analysis) from 15 genomic regions, including SNPs in or near genes involved in cellular adhesion, leukocyte migration and atherosclerosis (PECAM1, rs1867624), coagulation and inflammation (PROCR, rs867186 (p.Ser219Gly)) and vascular smooth muscle cell differentiation (LMOD1, rs2820315). Correlation of these regions with cell-type-specific gene expression and plasma protein levels sheds light on potential disease mechanisms
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