61,267 research outputs found

    Precision Measurements of Particle Masses using Jets at LEP2

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    How massive elementary particles get their mass is one of the greatest open questions in physics. Two of the major goals of the current LEP2 physics program that help to address this question are (a) to measure as precisely as possible the W Boson mass mW and (b) to exclude or discover the Higgs Boson within the available kinematic region. The reconstruction of invariant masses with jets from 4-jet channels (e.g. WW -> q qbar q qbar and HZ -> b bbar q qbar) and missing energy channels (e.g WW -> e nu q qbar and e+e- -> H nu nubar) is discussed. The emphasis is on the determination of mW, from which the role of calorimetry in such a precision measurement is emphasised

    Fluid injection device for high-pressure systems

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    Screw activated device, consisting of a compressor, shielded replaceable ampules, a multiple-element rubber gland, and a specially constructed fluid line fitting, injects measured amounts of fluids into a pressurized system. It is sturdy and easily manipulated

    How e-portfolio technologies can support the employer engagement agenda

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    Environmental distribution of Bathonian (Middle Jurassic) neoselachians in southern England

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    Within the Bathonian (Middle Jurassic) a wide range of depositional environments were present across Britain. Within this dominantly carbonate shelf setting, there is a general palaeoenvironmental transition from open marine shelf in the south of England, to marine and non-marine lagoons in south-central England. Isolated teeth of neoselachians are frequent at several localities within a range of marine and lagoonal facies. Extensive bulk sampling has allowed teeth from over 20 neoselachian taxa to be recovered from several distinct facies. The distributions of many species suggest that they were strongly environmentally controlled, with few taxa being commonly present within both open marine and lagoonal settings. Some taxonomic groups appear to have been restricted to specific environments, with hexanchids and palaeospinacids only being recorded within open marine facies. Within other groups, environmental segregation is at generic and specific level, with different species of Protospinax, orectolobids, batoids and scyliorhinids being recorded within different facies. The differential distribution of neoselachians within the Bathonian demonstrates that the initial phase of neoselachian radiation during the late Early and Middle Jurassic was accompanied by diversification into a wide range of ecological niches. This greatly increases our understanding of the mechanisms and timing of neoselachian radiation and Jurassic fish palaeoecolog

    Pedestrian demand modelling of large cities: an applied example from London

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    This paper introduces a methodology for the development of city wide pedestrian demand models and shows its application to London. The approach used for modelling is Multiple Regression Analysis of independent variables against the dependent variable of observed pedestrian flows. The test samples were from manual observation studies of average total pedestrian flow per hour on 237 sample sites. The model will provide predicted flow values for all 7,526 street segments in the 25 square kilometres of Central London. It has been independently validated by Transport for London and is being tested against further observation data. The longer term aim is to extend the model to the entire greater London area and to incorporate additional policy levers for use as a transport planning and evaluation tool
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