2,274 research outputs found

    The Monge problem in Wiener Space

    Full text link
    We address the Monge problem in the abstract Wiener space and we give an existence result provided both marginal measures are absolutely continuous with respect to the infinite dimensional Gaussian measure {\gamma}

    Uncertainties in Atmospheric Neutrino Fluxes

    Get PDF
    An evaluation of the principal uncertainties in the computation of neutrino fluxes produced in cosmic ray showers in the atmosphere is presented. The neutrino flux predictions are needed for comparison with experiment to perform neutrino oscillation studies. The paper concentrates on the main limitations which are due to hadron production uncertainties. It also treats primary cosmic ray flux uncertainties, which are at a lower level. The absolute neutrino fluxes are found to have errors of around 15% in the neutrino energy region important for contained events underground. Large cancellations of these errors occur when ratios of fluxes are considered, in particular, the νμ/νˉμ\nu_\mu/\bar{\nu}_\mu ratio below Eν=1E_\nu=1 GeV, the (νμ+νˉμ)/(νe+νˉe)(\nu_\mu+\bar{\nu}_\mu)/(\nu_e+\bar{\nu}_e) ratio below Eν=10E_\nu=10 GeV and the up/down ratios above Eν=1E_\nu=1 GeV are at the 1% level. A detailed breakdown of the origin of these errors and cancellations is presented.Comment: 14 pages, 22 postscript figures, written in Revte

    Search for nuclearites with the SLIM detector

    Full text link
    We discuss the properties of cosmic ray nuclearites, from the point of view of their search with large nuclear track detector arrays exposed at different altitudes, in particular with the SLIM experiment at the Chacaltaya high altitude lab (5290 m a.s.l.). We present calculations concerning their propagation in the Earth atmosphere and discuss their possible detection with CR39 and Makrofol nuclear track detectors.Comment: 11 pages, 6 figure

    Calculus and heat flow in metric measure spaces and applications to spaces with Ricci bounds from below

    Get PDF
    This paper is devoted to a deeper understanding of the heat flow and to the refinement of calculus tools on metric measure spaces (X,d,m). Our main results are: - A general study of the relations between the Hopf-Lax semigroup and Hamilton-Jacobi equation in metric spaces (X,d). - The equivalence of the heat flow in L^2(X,m) generated by a suitable Dirichlet energy and the Wasserstein gradient flow of the relative entropy functional in the space of probability measures P(X). - The proof of density in energy of Lipschitz functions in the Sobolev space W^{1,2}(X,d,m). - A fine and very general analysis of the differentiability properties of a large class of Kantorovich potentials, in connection with the optimal transport problem. Our results apply in particular to spaces satisfying Ricci curvature bounds in the sense of Lott & Villani [30] and Sturm [39,40], and require neither the doubling property nor the validity of the local Poincar\'e inequality.Comment: Minor typos corrected and many small improvements added. Lemma 2.4, Lemma 2.10, Prop. 5.7, Rem. 5.8, Thm. 6.3 added. Rem. 4.7, Prop. 4.8, Prop. 4.15 and Thm 4.16 augmented/reenforced. Proof of Thm. 4.16 and Lemma 9.6 simplified. Thm. 8.6 corrected. A simpler axiomatization of weak gradients, still equivalent to all other ones, has been propose

    New records of Pteridophytes in the semi-arid region of Brazil.

    Get PDF
    The goal of this paper is to enumerate the pteridophytes that occur in the semi-árid region of the State of Pernambuco, Brazil

    Interaction between sucrose and pH during in vitro culture of Nephrolepis biserrata (Sw.) Schott (Pteridophyta).

    Get PDF
    Interaction between sucrose and pH during in vitro culture of Nephrolepis biserrata (Sw.) Schott (Pteridophyta)). The present work reports the effect of different pH and sucrose concentrations on in vitro propagation of Nephrolepis biserrata. Fronds aseptically obtained from stolon segment culture were cultivated in MS semi-solid medium supplemented with 0, 15, 30, 45 and 60 g.L -1 sucrose and pH adjusted to 3, 5, 7 and 9, in a factorial design. Frond number and length, pinnae number, raquis length and diam eter, fresh and dry matter weight were measured. Inhibition of shoot and leaf regeneration was observed in all the pH treatments in the abs ence of sucrose. On the other hand, when sucrose was added to the medium, the shoot number increased, reaching the maximum average values of 51.25 and 38.25 shoot per explant at pH 5 and 7, respectively. Sucrose concentrations from 15 to 45g.L -1 increased leaf length and diameter and the pH 9 did not affect the dry matter weight, and was still not adequate for development of new fronds. Young sporophytes were successfully acclimated

    Time correlations of high energy muons in an underground detector

    Full text link
    We present the result of a search for correlations in the arrival times of high energy muons collected from 1995 till 2000 with the streamer tube system of the complete MACRO detector at the underground Gran Sasso Lab. Large samples of single muons (8.6 million), double muons (0.46 million) and multiple muons with multiplicities from 3 to 6 (0.08 million) were selected. These samples were used to search for time correlations of cosmic ray particles coming from the whole upper hemisphere or from selected space cones. The results of our analyses confirm with high statistics a random arrival time distribution of high energy cosmic rays.Comment: (12 pages, 7 figures, Accepted for publication in Astroparticle Physics

    SBV Regularity for Genuinely Nonlinear, Strictly Hyperbolic Systems of Conservation Laws in one space dimension

    Get PDF
    We prove that if tu(t)BV(R)t \mapsto u(t) \in \mathrm {BV}(\R) is the entropy solution to a N×NN \times N strictly hyperbolic system of conservation laws with genuinely nonlinear characteristic fields ut+f(u)x=0, u_t + f(u)_x = 0, then up to a countable set of times {tn}nN\{t_n\}_{n \in \mathbb N} the function u(t)u(t) is in SBV\mathrm {SBV}, i.e. its distributional derivative uxu_x is a measure with no Cantorian part. The proof is based on the decomposition of ux(t)u_x(t) into waves belonging to the characteristic families u(t)=i=1Nvi(t)r~i(t),vi(t)M(R), r~i(t)RN, u(t) = \sum_{i=1}^N v_i(t) \tilde r_i(t), \quad v_i(t) \in \mathcal M(\R), \ \tilde r_i(t) \in \mathrm R^N, and the balance of the continuous/jump part of the measures viv_i in regions bounded by characteristics. To this aim, a new interaction measure \mu_{i,\jump} is introduced, controlling the creation of atoms in the measure vi(t)v_i(t). The main argument of the proof is that for all tt where the Cantorian part of viv_i is not 0, either the Glimm functional has a downward jump, or there is a cancellation of waves or the measure μi,jump\mu_{i,\mathrm{jump}} is positive

    CPT-violating neutrino oscillations

    Full text link
    We propose a simple phenomenological model predicting, through Lorentz symmetry breaking, a CPT-violating asymmetry between particle and antiparticle states in neutrino oscillations involving sterile neutrinos. Such a model is able to explain the apparently observed anomalous excess of low-energy \nu_e-like events, reported by the MiniBooNE collaboration, as well as the non-observation of the corresponding anomalous excess of \ov{\nu}_e-like events. The present model leads to very specific physical predictions in the neutrino oscillations scenario, and account for the observed anomalies in terms of only one CPT-Lorentz violation parameter of the order of the Grand-Unification energy scale.Comment: revtex, 4 pages, no figure

    Puerperal Complications Following Elective Cesarean Sections for Twin Pregnancies

    Get PDF
    OBJECTIVE: To estimate the maternal puerperal morbidity in elective and emergent cesareans in twins. STUDY DESIGN: We evaluated postpartum complications among patients who underwent elective cesarean birth for twin pregnancy. This group was compared to matched singletons and to emergent cesareans in twins. RESULTS: During the period September 1994-March 2006 there were 299 (47.4%) elective and 80 (12.7%) emergent cesarean sections in twin pregnancies, for a total of 379 (60.1%) cesarean births for both twins. Controls included 299 cases of elective cesareans in singletons. The comparison between elective and emergent cesareans and between elective cesareans in twins and in singletons found no significant differences in postpartum fever, scar infection, and postpartum hemorrhage. Venous thromboembolism occurred in two twin pregnancies, one in the elective and one in the emergent cesarean group. Postpartum hysterectomy was required in a singleton pregnancy following an elective cesarean birth. CONCLUSION: At present, no data exist to show a disadvantage for a planned cesarean birth for twins.info:eu-repo/semantics/publishedVersio
    corecore