21 research outputs found

    Correlations in transverse momentum in pion-proton and kaon-proton collisions at 250 GeV/c

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    We have measured the second-order normalized differential factorial moments as a function of the difference of transverse momentum (ΔpT\Delta p_T) in \p^+ p and K+pK^+ p collisions at 250 GeV/cc. The second-order differential factorial moments for like-charged pairs reveal a strong increase with decreasing ΔpT\Delta p_T. In a small central rapidity window this increase is described by a simple power law. Such a behavior, if interpreted as originating from Bose-Einstein correlations, may indicate a structure of the transverse spatial distribution of the source similar to that recently predicted by Bia\l{}as and Peschanski for color-dipole emission in onium-onium scattering. The power of the rise obtained in the fit agrees with the predicted value.Comment: Talk presented at the 7th Workshop on Multiparticle Production ``Correlations and Fluctuations'', Nijmegen, The Netherlands, 30th June-6th July, 1996. Latex, 7 pages, uses epsfig.sty, pennames.sty (included), 1 eps figur

    A global reanalysis of nuclear parton distribution functions

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    We determine the nuclear modifications of parton distribution functions of bound protons at scales Q21.69Q^2\ge 1.69 GeV2^2 and momentum fractions 105x110^{-5}\le x\le 1 in a global analysis which utilizes nuclear hard process data, sum rules and leading-order DGLAP scale evolution. The main improvements over our earlier work {\em EKS98} are the automated χ2\chi^2 minimization, simplified and better controllable fit functions, and most importantly, the possibility for error estimates. The resulting 16-parameter fit to the N=514 datapoints is good, χ2/d.o.f=0.82\chi^2/{\rm d.o.f}=0.82. Within the error estimates obtained, the old {\em EKS98} parametrization is found to be fully consistent with the present analysis, with no essential difference in terms of χ2\chi^2 either. We also determine separate uncertainty bands for the nuclear gluon and sea quark modifications in the large-xx region where they are not stringently constrained by the available data. Comparison with other global analyses is shown and uncertainties demonstrated. Finally, we show that RHIC-BRAHMS data for inclusive hadron production in d+Au collisions lend support for a stronger gluon shadowing at x<0.01x<0.01 and also that fairly large changes in the gluon modifications do not rapidly deteriorate the goodness of the overall fits, as long as the initial gluon modifications in the region x0.020.04x\sim 0.02-0.04 remain small.Comment: 33 pages, 14 figure

    Modelling of Effective Thermal Conductivity of Composites Filled with Core-Shell Fillers

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    An effective model to calculate thermal conductivity of polymer composites using core-shell fillers is presented, wherein a core material of filler grains is covered by a layer of a high-thermal-conductivity (HTC) material. Such fillers can provide a significant increase of the composite thermal conductivity by an addition of a small amount of the HTC material. The model employs the Lewis-Nielsen formula describing filled systems. The effective thermal conductivity of the core-shell filler grains is calculated using the Russel model for porous materials. Modelling results are compared with recent measurements made on composites filled with cellulose microbeads coated with hexagonal boron nitride (h-BN) platelets and good agreement is demonstrated. Comparison with measurements made on epoxy composites, using silver-coated glass spheres as a filler, is also provided. It is demonstrated how the modelling procedure can improve understanding of properties of materials and structures used and mechanisms of thermal conduction within the composite

    The effects of artificial light at night (ALAN) on the gaping activity and feeding of mussels

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    Artificial Light at Night (ALAN) is a common environmental pollutant which affects &gt;22 % of the world's coastlines. However, the impact of ALAN wavelengths on coastal organisms is under-investigated. Here, we tested the impact of red, green, and white ALAN on the gaping activity and phytoplankton consumption of Mytilus edulis mussels and compared these to dark night. Mussels exhibited a semi-diel activity pattern. Although ALAN did not significantly affect the time open nor the phytoplankton consumption, it did have a colour-specific effect on the gaping frequency with red and white ALAN resulting in lower activity compared to the dark night. Green ALAN caused higher gaping frequency and a negative relationship between consumption and proportion of time open compared to the other treatments. Our findings suggest colour-specific ALAN effects on mussels and call for further investigation on the associated physiological mechanisms and potential ecological consequences
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