43 research outputs found

    Relic Neutrino Absorption Spectroscopy

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    Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10^{21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m_{nu} >~ 0.1 eV for the lightest neutrino. With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably.Comment: 19 pages, 26 figures, REVTeX

    Scale-free static and dynamical correlations in melts of monodisperse and Flory-distributed homopolymers: A review of recent bond-fluctuation model studies

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    It has been assumed until very recently that all long-range correlations are screened in three-dimensional melts of linear homopolymers on distances beyond the correlation length ξ\xi characterizing the decay of the density fluctuations. Summarizing simulation results obtained by means of a variant of the bond-fluctuation model with finite monomer excluded volume interactions and topology violating local and global Monte Carlo moves, we show that due to an interplay of the chain connectivity and the incompressibility constraint, both static and dynamical correlations arise on distances r≫ξr \gg \xi. These correlations are scale-free and, surprisingly, do not depend explicitly on the compressibility of the solution. Both monodisperse and (essentially) Flory-distributed equilibrium polymers are considered.Comment: 60 pages, 49 figure

    Miíase primária em coelho doméstico causada por Lucilia eximia (Diptera: Calliphoridae) no Brasil: relato de caso Primary myiasis in a domestic rabbit caused by Lucilia eximia (Diptera: Calliphoridae) in Brazil: case report

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    Relata-se a ocorrência de miíase primária em coelho doméstico Oryctolagus cuniculus (Lagomorpha: Leporidae) causada por Lucilia eximia (Diptera: Calliphoridae) em área urbana do município de Campinas, São Paulo.<br>The occurrence of primary myiasis in a domestic rabbit Oryctolagus cuniculus (Lagomorpha: Leporidae) caused by Lucilia eximia (Diptera: Calliphoridae) is reported in an urban area in the city of Campinas, São Paulo, Brazil

    The communication bottleneck in knitwear design: Analysis and computing solutions

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    Communication between different members of a designteam often poses difficulties. This paper reports onthe results of a detailed empirical study ofcommunication in over twenty British, German andItalian knitwear companies. The knitwear designprocess is shared by the designers, who plan thevisual and tactile appearance of the garments, and thetechnicians, who have to realise the garment on aknitting machine. They comprise a typical but smalldesign team whose members have different backgroundsand expertise. Knitwear design allows a detailedanalysis of the causes and effects of communicationbreakdown. Designers specify their designsinaccurately, incompletely and inconsistently;technicians interpret these specifications accordingto their previous experience of similar designs, andproduce garments very different from the designers'original intentions. Knitwear is inherently difficultto describe, as no simple and complete notationexists; and the relationship between visual appearanceand structure and technical properties of knittedfabric is subtle and complex. Designers andtechnicians have different cognitive approaches andare very different people. At the same time theinteraction between designers and technicians is badlymanaged in many companies. This paper argues thatimproving the accuracy and reliability of designers'specifications would significantly enhance the designprocess. It concludes with a description of thearchitecture of an intelligent automatic design systemthat generates technically correct designs from thedesigners' customary notations
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