Single-Photon Observables and Preparation Uncertainty Relations

We propose a procedure for defining all single-photon observables in terms of Positive-Operator Valued Measures (POVMs), in particular spin and position. We identify the suppression of $0$-helicity photon states as a projection from an extended Hilbert space onto the photon Hilbert space. We show that all single-photon observables are in general described by POVMs, obtained by applying this projection to opportune Projection-Valued Measures (PVMs), defined on the extended Hilbert space. The POVMs associated to momentum and helicity reduce to PVMs, unlike those associated to position and spin, this fact reflecting the intrinsic unsharpness of these observables. We finally extensively study the preparation uncertainty relations for position and momentum and the probability distribution of spin, exploring single photon Gaussian states for several choices of spin and polarization.Comment: 25 pages (7 Figures); revised and extended version; in submissio

Discovery of a 6.4 h black hole binary in NGC 4490

We report on the discovery with Chandra of a strong modulation (~90% pulsed fraction) at ~6.4 h from the source CXOU J123030.3+413853 in the star-forming, low-metallicity spiral galaxy NGC 4490, which is interacting with the irregular companion NGC 4485. This modulation, confirmed also by XMM-Newton observations, is interpreted as the orbital period of a binary system. The spectra from the Chandra and XMM-Newton observations can be described by a power-law model with photon index ~1.5. During these observations, which span from 2000 November to 2008 May, the source showed a long-term luminosity variability by a factor of ~5, between ~2E+38 and 1.1E+39 erg/s (for a distance of 8 Mpc). The maximum X-ray luminosity, exceeding by far the Eddington limit of a neutron star, indicates that the accretor is a black hole. Given the high X-ray luminosity, the short orbital period and the morphology of the orbital light curve, we favour an interpretation of CXOU J123030.3+413853 as a rare high-mass X-ray binary system with a Wolf-Rayet star as a donor, similar to Cyg X-3. This would be the fourth system of this kind known in the local Universe. CXOU J123030.3+413853 can also be considered as a transitional object between high mass X-ray binaries and ultraluminous X-ray sources (ULXs), the study of which may reveal how the properties of persistent black-hole binaries evolve entering the ULX regime.Comment: Fig. 1 in reduced quality; minor changes to match the MNRAS versio

Spectral variability in Swift and Chandra observations of the Ultraluminous source NGC 55 ULX1

NGC 55 ULX1 is a bright Ultraluminous X-ray source located 1.78 Mpc away. We analysed a sample of 20 Swift observations, taken between 2013 April and August, and two Chandra observations taken in 2001 September and 2004 June. We found only marginal hints of a limited number of dips in the light curve, previously reported to occur in this source, although the uncertainties due to the low counting statistics of the data are large. The Chandra and Swift spectra showed clearly spectral variability which resembles those observed in other ULXs. We can account for this spectral variability in terms of changes in both the normalization and intrinsic column density of a two-components model consisting of a blackbody (for the soft component) and a multicolour accretion disc (for the hard component). We discuss the possibility that strong outflows ejected by the disc are in part responsible for such spectral changes.Comment: 9 pages, 6 figure; accepted to be published on MNRA

Inovação no desenvolvimento de embalagens para frutas e vegetais in natura

A maioria das pessoas não se dá conta que as embalagens para hortifruticolas acondicionam seres vivos. Estas embalagens possuem significados e usos tão específicos que mereceriam estar catalogadas numa categoria particular e não na categoria genérica de embalagens para alimentos. Os seres vivos que acondicionam pertencem a diversos tipos, espécies e categorias, e possuem qualidades essenciais e características organolépticas, sensoriais únicas. Por isto, as embalagens para hortofruticolas, e o seu processo de desenvolvimento, devem que respeitar o caráter único de cada produto. O desrespeito a este caráter único tem contribuído fortemente para que as embalagens reduzam o tempo de vida útil das frutas, legumes e verduras e aumentem as perdas pós-colheita. As embalagens não devem ser genéricas. Contudo, esta não tem sido a visão dos projetistas e dos produtores industriais das embalagens para hortifruticolas. A Divisão de Desenho Industrial do Instituto Nacional de Tecnologia criou um processo – e método – inovador de design para o projeto de embalagens para frutas, legumes e verduras, que respeita as singularidades de cada tipo de produto. Apresentamos este processo e método neste artigo. Submetemos a avaliações - sob o ponto de vista de redução das perdas -, estas novas embalagens em comparação com todas as outras existentes no Brasil. Escolhemos as embalagens para caquis (Diospyros kaki) para demonstrar estas avaliações porque no Brasil perde-se, nos processos de pós-colheita, cerca de 80 % de todo o caqui plantado.ABSTRACT: Most people do not realize that the packaging for horticultural contained living beings. These packages have specific meanings and uses that deserve to be cataloged in a particular category and not in the general category of food packaging. Living beings contained therein belong to various types, species and categories, and have unique essential qualities, organolep_c properties and sensory characteristics. Therefore, the packaging for horticultural, and its development process, must respect the unique character of each product. Failure to comply with this unique character have contributed strongly to the packaging reduce the useful life of fruits and vegetables and increase post-harvest losses. Packaging must not be generic. However, this has not been the vision of designers and industrial producers of packaging for horticultural. We present this process and method in this paper. We submit to assessments these new packages compared with all other existing in Brazil, from the point of view reducing losses. We chose the packaging for persimmons (Diospyros kaki) to demonstrate these assessments because in Brazil in the post-harvest processes about 80% of all planted persimmon are lost.info:eu-repo/semantics/publishedVersio