2,464 research outputs found

    Quark model predictions for K∗K^* photoproduction on the proton

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    The photoproduction of K∗K^* vector mesons is investigated in a quark model with an effective Lagrangian. Including both baryon resonance excitations and {\it t}-channel exchanges, observables for the reactions γp→K∗0Σ+\gamma p\to K^{*0}\Sigma^+ and γp→K∗+Σ0\gamma p\to K^{*+}\Sigma^0 are predicted, using the SU(3)-flavor-blind assumption of non-perturbative QCD.Comment: Revtex, 3 eps figures, revised version accepted by PRC Rapid Comm

    Theory of periodic swarming of bacteria: application to Proteus mirabilis

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    The periodic swarming of bacteria is one of the simplest examples for pattern formation produced by the self-organized collective behavior of a large number of organisms. In the spectacular colonies of Proteus mirabilis (the most common species exhibiting this type of growth) a series of concentric rings are developed as the bacteria multiply and swarm following a scenario periodically repeating itself. We have developed a theoretical description for this process in order to get a deeper insight into some of the typical processes governing the phenomena in systems of many interacting living units. All of our theoretical results are in excellent quantitative agreement with the complete set of available observations.Comment: 11 pages, 8 figure

    Young star clusters in M31

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    In our study of M31's globular cluster system with MMT/Hectospec, we have obtained high-quality spectra of 85 clusters with ages less than 1 Gyr. With the exception of Hubble V, the young cluster in NGC 205, we find that these young clusters have kinematics and spatial distribution consistent with membership in M31's young disk. Preliminary estimates of the cluster masses and structural parameters, using spectroscopically derived ages and HST imaging, confirms earlier suggestions that M31 has clusters similar to the LMC's young populous clusters.Comment: 4 pages, 1 figure, contributed talk at "Galaxies in the Local Volume" conference in Sydney, July 200

    HadISDH: an updateable land surface specific humidity product for climate monitoring

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    HadISDH is a near-global land surface specific humidity monitoring product providing monthly means from 1973 onwards over large-scale grids. Presented herein to 2012, annual updates are anticipated. HadISDH is an update to the land component of HadCRUH, utilising the global high-resolution land surface station product HadISD as a basis. HadISD, in turn, uses an updated version of NOAA's Integrated Surface Database. Intensive automated quality control has been undertaken at the individual observation level, as part of HadISD processing. The data have been subsequently run through the pairwise homogenisation algorithm developed for NCDC's US Historical Climatology Network monthly temperature product. For the first time, uncertainty estimates are provided at the grid-box spatial scale and monthly timescale. HadISDH is in good agreement with existing land surface humidity products in periods of overlap, and with both land air and sea surface temperature estimates. Widespread moistening is shown over the 1973–2012 period. The largest moistening signals are over the tropics with drying over the subtropics, supporting other evidence of an intensified hydrological cycle over recent years. Moistening is detectable with high (95%) confidence over large-scale averages for the globe, Northern Hemisphere and tropics, with trends of 0.089 (0.080 to 0.098) g kg−1 per decade, 0.086 (0.075 to 0.097) g kg−1 per decade and 0.133 (0.119 to 0.148) g kg−1 per decade, respectively. These changes are outside the uncertainty range for the large-scale average which is dominated by the spatial coverage component; station and grid-box sampling uncertainty is essentially negligible on large scales. A very small moistening (0.013 (−0.005 to 0.031) g kg−1 per decade) is found in the Southern Hemisphere, but it is not significantly different from zero and uncertainty is large. When globally averaged, 1998 is the moistest year since monitoring began in 1973, closely followed by 2010, two strong El Niño years. The period in between is relatively flat, concurring with previous findings of decreasing relative humidity over land

    MOTIVATING EFFECTIVE ICT USERS’ SUPPORT THROUGH AUTOMATED MOBILE EDU-HELPDESK SYSTEM

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    An automated helpdesk system is meant to eradicate some of the barriers of reaching the Information and Communication Technology (ICT) technical staff to carry out repairs of ICT products and services in an educational institution. The problems faced with the existing ICT user support system include time wasting, difficulty in communication, and slow response to fix ICT related faults. The objective of this study is to develop an Automated Mobile Edu-Helpdesk System (AMES) for effective information dissemination, efficient management of operations and to resolve ICT challenges in higher education. The research methods adopted include unified modelling diagrams for design, Java and XML (Extended Mark-up Language) for Android application development as front end, while Hypertext Preprocessor (PHP) was used as the server side programming tool. MySQL database was used as backend. Findings: The findings from the usability survey shows a good usability based on total rating of 4.09 out of 5 point scale. The benefits of the system include creation of a medium for non teaching and teaching staff to pass their complaints or messages to the technical department for speedy attention; and provision of better and faster operational processes which will reduce time spent on documentation. The automated Edu-Helpdesk system is more reliable, effective and convenient than the manual method in reporting cases of faulty ICT product and services within the university community
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