Evidence for a resonant cyclotron line in IGR J16493-4348 from the Swift-BAT hard X-ray survey

Resonant absorption cyclotron features are a key diagnostic tool to directly measure the strength of the magnetic field of accreting neutron stars. However, typical values for cyclotron features lie in the high-energy part of the spectrum between 20 keV and 50 keV, where detection is often damped by the low statistics from single pointed observations. We show that long-term monitoring campaign performed with Swift-BAT of persistently, but faint, accreting high-mass X-ray binaries is able to reveal in their spectra the presence of cyclotron features. We extracted the average Swift-BAT 15-150 keV spectrum from the 54 months long Swift-BAT survey of the high-mass X-ray source IGR J16493-4348. To constrain the broadband spectrum we used soft X-ray spectra from Swift-XRT and Suzaku pointed observations. We model the spectra using a set of phenomenological models usually adopted to describe the energy spectrum of accreting high-mass X-ray binaries; irrespective of the models we used, we found significant improvements in the spectral fits adding to the models a broad (10 keV width) absorption feature, with best-fitting energy estimate between 30 and 33 keV, that we interpret as evidence for a resonant cyclotron absorption feature. We also discuss instrumental issues related to the use of Swift-BAT for this kind of studies and the statistical method to weight the confidence level of this detection. Correcting for the gravitational redshift of a 1.4 M_{\sun} neutron star, the inferred surface magnetic field is Bsurf 3.7 x 10^{12} Gauss. The spectral parameters of IGR J16493-4348 fit well with empirical correlations observed when the whole sample of high-mass binaries with detected cyclotron features is considered.Comment: Published in Astronomy & Astrophysics, 2011, 532, A7

Advanced Ultrasonic Non-destructive Evaluation for Metrological Analysis and Quality Assessment of Impact Damaged Non-crimp Fabric Composites☆

Abstract Composite materials are nowadays massively utilized in a very large number of industrial applications. Thus, it has become essential to characterize the service behaviour they can provide depending on their working conditions. In this paper, the study of the influence of impact conditions on damage generation in high performance composite materials, consisting of non-crimp fabric composite laminates, is carried out through the application of an advanced ultrasonic non-destructive evaluation technique, known as full volume ultrasonic scanning. This technique is based on the pulse-echo immersion testing method and allows for the quantitative analysis of the internal material structure in the entire composite volume. The aim of the ultrasonic non-destructive evaluation analysis is the metrological characterization of the non-crimp fabric composite laminates in terms of actual thickness estimation and stacking sequence fiber orientation verification as well as their quality assessment in terms of impact damage development within the whole composite material volume

New blazars from the cross-match of recent multi-frequency catalogs

Blazars are radio-loud active galactic nuclei well known for their non thermal emission spanning a wide range of frequencies. The Roma-BZCAT is, to date, the most comprehensive list of these sources. We performed the cross-match of several catalogs obtained from recent surveys at different frequencies to search for new blazars. We cross-matched the 1$^{st}$ Swift-XRT Point Source catalog with the spectroscopic sample of the 9$^{th}$ Data Release of the Sloan Digital Sky Survey. Then, we performed further cross-matches with the catalogs corresponding to the Faint Images of the Radio Sky at Twenty cm survey and to the AllWISE Data release, focusing on sources with infrared colors similar to those of confirmed $\gamma$-ray blazars included in the Second Fermi-LAT catalog. As a result, we obtained a preliminary list of objects with all the elements needed for a proper blazar classification according to the prescriptions of the Roma-BZCAT. We carefully investigated additional properties such as their morphology and the slope of their spectral energy distribution in the radio domain, the features shown in their optical spectrum, and the luminosity in the soft X rays to exclude generic active galactic nuclei and focus on authentic blazar-like sources. At the end of our screening we obtained a list of 15 objects with firmly established blazar properties.Comment: 8 pages, 3 figures, 1 table. Accepted for publication in Astrophysics and Space Science on 2015 April 25. Corrected typo in Section

advanced sensor signal feature extraction and pattern recognition for wire edm process monitoring

Wire electrical discharge machining (WEDM) is investigated in the perspective of zero-defect manufacturing with the scope to detect anomalous process conditions leading to typical defects generated during WEDM, i.e. the occurrence of lines and marks on the resulting workpiece surface. A multiple sensor monitoring system is employed to acquire high sampling rate sensorial data relative to signals of voltage and current in the gap between workpiece and wire electrode. An advanced signal processing methodology is implemented to extract and select the most relevant features useful to identify the undesired process conditions through a cognitive pattern recognition paradigm. (C) 2016 The Authors. Published by Elsevier B.V

VUV-Vis optical characterization of Tetraphenyl-butadiene films on glass and specular reflector substrates from room to liquid Argon temperature

The use of efficient wavelength-shifters from the vacuum-ultraviolet to the photosensor's range of sensitivity is a key feature in detectors for Dark Matter search and neutrino physics based on liquid argon scintillation detection. Thin film of Tetraphenyl-butadiene (TPB) deposited onto the surface delimiting the active volume of the detector and/or onto the photosensor optical window is the most common solution in current and planned experiments. Detector design and response can be evaluated and correctly simulated only when the properties of the optical system in use (TPB film + substrate) are fully understood. Characterization of the optical system requires specific, sometimes sophisticated optical methodologies. In this paper the main features of TPB coatings on different, commonly used substrates is reported, as a result of two independent campaigns of measurements at the specialized optical metrology labs of ENEA and University of Tor Vergata. Measured features include TPB emission spectra with lineshape and relative intensity variation recorded as a function of the film thickness and for the first time down to LAr temperature, as well as optical reflectance and transmittance spectra of the TPB coated substrates in the wavelength range of the TPB emission

The Swift-BAT survey reveals the orbital period of three high-mass X-ray binaries

A growing number of previously hidden Galactic X-ray sources are now detected with recent surveys performed by the Integral and Swift satellites. Most of these new sources eluded past surveys due to their large local X-ray extinction and consequent low soft X-ray flux. The Swift-BAT performs daily monitoring of the sky in an energy band (15-150 keV) which is only marginally affected by X-ray extinction, thus allowing for the search of long periodicities in the light curve and identification of the nature of the X-ray sources. We performed a period search using the folding technique in the Swift-BAT light curves of three Integral sources: IGR J05007-7047, IGR J13186-6257 and IGR J17354-3255. Their periodograms show significant peaks at 30.77$\pm$0.01 d, 19.994$\pm$0.01 d and 8.448$\pm$0.002 d, respectively. We estimate the significance of these features from the chi squared distribution of all the trials, finding a probability less than 1.5$\times10^{-4}$ that the detections occurred due to chance. We complement our analysis with the study of their broadband X-ray emission. We identify the periodicities with the orbital periods of the sources. The periods are typical for the wind accretors X-ray binaries and we support this identification showing that also their energy spectra are compatible with an X-ray spectral emission characteristic of high-mass X-ray binaries. The spectrum of IGR J05007-704 that resides in the Large Magellanic Cloud, does not show any intrinsic local absorption, whereas the spectra of the Galactic sources IGR J17354-3255 and IGR J13186-6257 may be affected by a local absorber. The folded light curve for IGR J13186-6257 suggests a possible Be companion star.Comment: 10 pages, 14 figures. Accepted for publication in A&

Quantitative determination of casein genetic variants in goat milk: Application in Girgentana dairy goat breed

The study was conducted to develop a high-performance liquid chromatographic (HPLC) method to quantify casein genetic variants (s2-, β-, and κ-casein) in milk of homozygous individuals of Girgentana goat breed. For calibration experiments, pure genetic variants were extracted from individual milk samples of animals with known genotypes. The described HPLC approach was precise, accurate and highly suitable for quantification of goat casein genetic variants of homozygous individuals. The amount of each casein per allele was: s2-casein A=2.9 ± 0.8 g/L and F=1.8 ± 0.4 g/L; β-casein C=3.0 ± 0.8 g/L and C1=2.0 ± 0.7 g/L and κ-casein A=1.6 ± 0.3 g/L and B=1.1 ± 0.2 g/L. A good correlation was found between the quantities of s2-casein genetic variants A and F, and β-casein C and C1 with other previously described method. The main important result was obtained for κ-casein because, till now, no data were available on quantification of single genetic variants for this protein

Non-contact Reverse Engineering Modeling for Additive Manufacturing of Down Scaled Cultural Artefacts

Abstract In recent years, reverse engineering has achieved a relevant role in the cultural heritage field. The availability of 3D digital models of artefacts opens the door to a new era of cultural heritage: virtual museum creation, artefact cataloguing, conservation, planning and simulation of restoration, monitoring of artefacts subjected to environmental degradation, virtual reconstruction of damaged or missing parts, reproduction of replicas, etc. In this paper, two different non-contact reverse engineering scanning systems were utilized for 3D data acquisition of a cultural heritage artefact. The digital data acquisition and processing procedures of the scanned geometry have been illustrated and compared to evaluate the performance of both systems in terms of data acquisition time, processing time, reconstruction precision and final model quality. Finally, additive manufacturing technologies were applied to reconstruct a down scaled copy of the artefact