445 research outputs found

    Body temperatures in two brazilian primates

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    O ciclo de temperatura corpórea diário do saguí Callithrix jacchus (4 o) tem uma amplitude de 4,3ºC, cêrca de 2 vêzes a observada em outros primatas e mais elevada em qualquer outro mamífero. O máximo foi às 9,30 horas (39,7 mais ou menos 0,98º) e o mínimo foi às 1,30 horas (35,4 mais ou menos 0,4º

    Analysis of intermittency in submillimeter radio and hard x-ray data during the impulsive phase of a solar flare

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    We present an analysis of intermittent processes occurring during the impulsive phase of the flare SOL2012-03-13, using hard X-rays and submillimeter radio data. Intermittency is a key characteristic in turbulent plasmas and has so far only been analyzed for hard X-ray data. Since in a typical flare the same accelerated electron population is believed to produce both hard X-rays and gyrosynchrotron radiation, we compare the two time profiles by searching for intermittency signatures. For this, we define a cross-wavelet power spectrum, which is used to obtain the local intermittency measure, or LIMLIM. When greater than three, the square LIMLIM coefficients indicate a local intermittent process. The LIM2LIM2 coefficient distribution in time and scale helps to identify avalanche or cascade energy release processes. We find two different and well-separated intermittent behaviors in the submillimeter data: for scales greater than 20 s, a broad distribution during the rising and maximum phases of the emission seems to favor a cascade process; for scales below 1 s, short pulses centered on the peak time are representative of avalanches. When applying the same analysis to hard X-rays, we find that only the scales above 10 s produce a distribution related to a cascade energy fragmentation. Our results suggest that different acceleration mechanisms are responsible for tens of keV and MeV energy ranges of electrons

    Dirac and Majorana heavy neutrinos at LEP II

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    The possibility of detecting single heavy Dirac and Majorana neutrinos at LEP II is investigated for heavy neutrino masses in the range MN=(s/2,s)M_N=(\sqrt s/2, \sqrt s). We study the process e+e−⟶νℓℓqiqˉje^+e^- \longrightarrow \nu_{\ell} \ell q_i \bar q_j as a clear signature for heavy neutrinos. Numerical estimates for cross sections and distributions for the signal and the background are calculated and a Monte Carlo reconstruction of final state particles after hadronization is presented.Comment: 4 pages, 8 figure

    Neutral heavy lepton production at next high energy e+e−e^+e^- linear colliders

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    The discovery potential for detecting new heavy Majorana and Dirac neutrinos at some recently proposed high energy e+e−e^+e^- colliders is discussed. These new particles are suggested by grand unified theories and superstring-inspired models. For these models the production of a single heavy neutrino is shown to be more relevant than pair production when comparing cross sections and neutrino mass ranges. The process e+e−⟶νe±W∓ e^+e^- \longrightarrow {\nu} e^{\pm} W^{\mp} is calculated including on-shell and off-shell heavy neutrino effects. We present a detailed study of cross sections and distributions that shows a clear separation between the signal and standard model contributions, even after including hadronization effects.Comment: 4 pages including 15 figures, 1 table. RevTex. Accepted in Physical Review
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