9,148 research outputs found

    Localization in the Rindler Wedge

    Get PDF
    One of the striking features of QED is that charged particles create a coherent cloud of photons. The resultant coherent state vectors of photons generate a non-trivial representation of the localized algebra of observables that do not support a representation of the Lorentz group: Lorentz symmetry is spontaneously broken. We show in particular that Lorentz boost generators diverge in this representation, a result shown also in [1] (See also [2]). Localization of observables, for example in the Rindler wedge, uses Poincar\'e invariance in an essential way [3]. Hence in the presence of charged fields, the photon observables cannot be localized in the Rindler wedge. These observations may have a bearing on the black hole information loss paradox, as the physics in the exterior of the black hole has points of resemblance to that in the Rindler wedge.Comment: 11 page

    Solving 1ODEs with functions

    Full text link
    Here we present a new approach to deal with first order ordinary differential equations (1ODEs), presenting functions. This method is an alternative to the one we have presented in [1]. In [2], we have establish the theoretical background to deal, in the extended Prelle-Singer approach context, with systems of 1ODEs. In this present paper, we will apply these results in order to produce a method that is more efficient in a great number of cases. Directly, the solving of 1ODEs is applicable to any problem presenting parameters to which the rate of change is related to the parameter itself. Apart from that, the solving of 1ODEs can be a part of larger mathematical processes vital to dealing with many problems.Comment: 31 page

    The influence of environmental complexity on the worker morphometry of ant assemblages

    Get PDF
    The objective of the present study was to test whether environmental complexity influences the morphology of leaf litter worker ants, as predicted by the size-grain hypothesis. We collected data from three types of vegetation (shrubby, shrubby-arboreal, and arboreal) in Restinga da Marambaia, southeastern Brazil. The shrubby vegetation had a very superficial leaf litter compared to the other two vegetation types. We measured head width, body length, and femur length of the ants collected in each vegetation type. We used average head width (HW) as a proxy for body size. The shrubby-arboreal and arboreal vegetation types were assumed to represent more rugose environments than the shrubby vegetation. Leg length allometry was observed in each and all vegetation types. We did not find significant differences in body size and allometry of ant assemblage among vegetation types. Hence, the size-grain hypothesis was corroborated only for leg allometry, but it did not predict a general environmental influence on ant morphometry

    Os recursos geneticos vegetais e os melhoristas de plantas.

    Get PDF
    Este trabalho apresenta uma análise sobre os pontos abordados à luz dos conhecimentos disponíveis na literatura pertinente e da situação vigente quanto aos recursos genéticos e ao melhoramento genético da região Nordeste

    Scaling up orange-fleshed sweetpotato through agriculture and nutrition (SUSTAIN) in Mozambique

    Get PDF
    SUSTAIN is a 5-year partnership (2013-2018), coordinated by CIP and financed by the UK Department for International Development, to scale up the nutrition benefits of biofortified orange-fleshed sweetpotato (OFSP). The goal is to reach 1.2 million households with under-5 year old children in Kenya, Malawi, Mozambique, and Rwanda. SUSTAIN supports integrated interventions in agriculture, nutrition, utilization, and marketing to strengthen production and consumption of OFSP. This flyer captures the work in Mozambique during the period June 2014 - July 2015

    Connectivity-dependent properties of diluted sytems in a transfer-matrix description

    Full text link
    We introduce a new approach to connectivity-dependent properties of diluted systems, which is based on the transfer-matrix formulation of the percolation problem. It simultaneously incorporates the connective properties reflected in non-zero matrix elements and allows one to use standard random-matrix multiplication techniques. Thus it is possible to investigate physical processes on the percolation structure with the high efficiency and precision characteristic of transfer-matrix methods, while avoiding disconnections. The method is illustrated for two-dimensional site percolation by calculating (i) the critical correlation length along the strip, and the finite-size longitudinal DC conductivity: (ii) at the percolation threshold, and (iii) very near the pure-system limit.Comment: 4 pages, no figures, RevTeX, Phys. Rev. E Rapid Communications (to be published
    corecore