1,050 research outputs found

    Hard X-ray selected giant radio galaxies - I. The X-ray properties and radio connection

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    We present the first broad-band X-ray study of the nuclei of 14 hard X-ray selected giant radio galaxies, based both on the literature and on the analysis of archival X-ray data from NuSTAR, XMM-Newton, Swift and INTEGRAL. The X-ray properties of the sources are consistent with an accretion-related X-ray emission, likely originating from an X-ray corona coupled to a radiatively efficient accretion flow. We find a correlation between the X-ray luminosity and the radio core luminosity, consistent with that expected for AGNs powered by efficient accretion. In most sources, the luminosity of the radio lobes and the estimated jet power are relatively low compared with the nuclear X-ray emission. This indicates that either the nucleus is more powerful than in the past, consistent with a restarting of the central engine, or that the giant lobes are dimmer due to expansion losses.Comment: 11 pages, 3 figures. Accepted for publication in MNRA

    An XMM-Newton look at the strongly variable radio-weak BL Lac Fermi J1544-0639

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    Fermi J1544-0639/ASASSN-17gs/AT2017egv was identified as a gamma-ray/optical transient on May 15, 2017. Subsequent multiwavelength observations suggest that this source may belong to the new class of radio-weak BL Lacs. We studied the X-ray spectral properties and short-term variability of Fermi J1544-0639 to constrain the X-ray continuum emission mechanism of this peculiar source. We present the analysis of an XMM-Newton observation, 56 ks in length, performed on February 21, 2018. The source exhibits strong X-ray variability, both in flux and spectral shape, on timescales of ~10 ks, with a harder-when-brighter behaviour typical of BL Lacs. The X-ray spectrum is nicely described by a variable broken power law, with a break energy of around 2.7 keV consistent with radiative cooling due to Comptonization of broad-line region photons. We find evidence for a `soft excess', nicely described by a blackbody with a temperature of ~0.2 keV, consistent with being produced by bulk Comptonization along the jet.Comment: 11 pages, 12 figures. Accepted for publication in Astronomy & Astrophysic

    Trapping polarization of light in nonlinear optical fibers: An ideal Raman polarizer

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    The main subject of this contribution is the all-optical control over the state of polarization (SOP) of light, understood as the control over the SOP of a signal beam by the SOP of a pump beam. We will show how the possibility of such control arises naturally from a vectorial study of pump-probe Raman interactions in optical fibers. Most studies on the Raman effect in optical fibers assume a scalar model, which is only valid for high-PMD fibers (here, PMD stands for the polarization-mode dispersion). Modern technology enables manufacturing of low-PMD fibers, the description of which requires a full vectorial model. Within this model we gain full control over the SOP of the signal beam. In particular we show how the signal SOP is pulled towards and trapped by the pump SOP. The isotropic symmetry of the fiber is broken by the presence of the polarized pump. This trapping effect is used in experiments for the design of new nonlinear optical devices named Raman polarizers. Along with the property of improved signal amplification, these devices transform an arbitrary input SOP of the signal beam into one and the same SOP towards the output end. This output SOP is fully controlled by the SOP of the pump beam. We overview the sate-of-the-art of the subject and introduce the notion of an "ideal Raman polarizer"

    Aging in humid granular media

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    Aging behavior is an important effect in the friction properties of solid surfaces. In this paper we investigate the temporal evolution of the static properties of a granular medium by studying the aging over time of the maximum stability angle of submillimetric glass beads. We report the effect of several parameters on these aging properties, such as the wear on the beads, the stress during the resting period, and the humidity content of the atmosphere. Aging effects in an ethanol atmosphere are also studied. These experimental results are discussed at the end of the paper.Comment: 7 pages, 9 figure

    Anatomy of the AGN in NGC 5548: I. A global model for the broadband spectral energy distribution

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    An extensive multi-satellite campaign on NGC 5548 has revealed this archetypal Seyfert-1 galaxy to be in an exceptional state of persistent heavy absorption. Our observations taken in 2013-2014 with XMM-Newton, Swift, NuSTAR, INTEGRAL, Chandra, HST and two ground-based observatories have together enabled us to establish that this unexpected phenomenon is caused by an outflowing stream of weakly ionised gas (called the obscurer), extending from the vicinity of the accretion disk to the broad-line region. In this work we present the details of our campaign and the data obtained by all the observatories. We determine the spectral energy distribution of NGC 5548 from near-infrared to hard X-rays by establishing the contribution of various emission and absorption processes taking place along our line of sight towards the central engine. We thus uncover the intrinsic emission and produce a broadband continuum model for both obscured (average summer 2013 data) and unobscured (<< 2011) epochs of NGC 5548. Our results suggest that the intrinsic NIR/optical/UV continuum is a single Comptonised component with its higher energy tail creating the 'soft X-ray excess'. This component is compatible with emission from a warm, optically-thick corona as part of the inner accretion disk. We then investigate the effects of the continuum on the ionisation balance and thermal stability of photoionised gas for unobscured and obscured epochs.Comment: Accepted for publication in A&A, 19 pages, 13 figure

    Fdm layering deposition effects on mechanical response of tpu lattice structures

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    Nowadays, fused deposition modeling additive technology is becoming more and more popular in parts manufacturing due to its ability to reproduce complex geometries with many different thermoplastic materials, such as the TPU. On the other hand, objects obtained through this technology are mainly used for prototyping activities. For this reason, analyzing the functional behavior of FDM parts is still a topic of great interest. Many studies are conducted to broaden the spectrum of materials used to ensure an ever-increasing use of FDM in various production scenarios. In this study, the effects of several phenomena that influence the mechanical properties of printed lattice structures additively obtained by FDM are evaluated. Three different configurations of lattice structures with designs developed from unit cells were analyzed both experimentally and numerically. As the main result of the study, several parameters of the FDM process and their correlation were identified as possible detrimental factors of the mechanical properties by about 50% of the same parts used as isotropic cell solids. The best parameter configurations in terms of mechanical response were then highlighted by numerical analysis

    Contract Formation Jurisdiction of the United States Claims Court

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    This new United States Court of Appeals for the Federal Circuit has jurisdiction over appeals in contract and patent infringement cases. The former Court of Claims\u27 trial division has also been replaced with a new United States Claims Court. This court, inter alia, has been invested with the jurisdiction to conduct trials in contract and patent cases. Of particular interest to the government contracting community, is the provision of the Act regarding the contract formation or pre-award jurisdiction of the new Claims Court. The Claims Court has the potential to provide the most effective forum for the resolution of protests against the award of federal government contracts. Early decisions by the Claims Court defining both the court\u27s jurisdiction over pre-award issues and the scope of review in cases found to be within the court\u27s jurisdiction, however, raised substantial fears whether that potential ever would be reached. The March 23, 1983 decision of the new Court of Appeals for the Federal Circuit in United States v. Grimberg Co. and subsequent Claims Court opinions applying that decision now confirm those fears. Section I looks at the situation in government contracts cases before the creation of the new court. Section II briefly acknowledges the limitations of the former system, and how Congress sought to fix these problems in the Federal Courts Improvement Act. Then Section II turns to discuss the decision in US v. Grimberg

    Selenoprotein gene nomenclature

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    The human genome contains 25 genes coding for selenocysteine-containing proteins (selenoproteins). These proteins are involved in a variety of functions, most notably redox homeostasis. Selenoprotein enzymes with known functions are designated according to these functions: TXNRD1, TXNRD2, and TXNRD3 (thioredoxin reductases), GPX1, GPX2, GPX3, GPX4 and GPX6 (glutathione peroxidases), DIO1, DIO2, and DIO3 (iodothyronine deiodinases), MSRB1 (methionine-R-sulfoxide reductase 1) and SEPHS2 (selenophosphate synthetase 2). Selenoproteins without known functions have traditionally been denoted by SEL or SEP symbols. However, these symbols are sometimes ambiguous and conflict with the approved nomenclature for several other genes. Therefore, there is a need to implement a rational and coherent nomenclature system for selenoprotein-encoding genes. Our solution is to use the root symbol SELENO followed by a letter. This nomenclature applies to SELENOF (selenoprotein F, the 15 kDa selenoprotein, SEP15), SELENOH (selenoprotein H, SELH, C11orf31), SELENOI (selenoprotein I, SELI, EPT1), SELENOK (selenoprotein K, SELK), SELENOM (selenoprotein M, SELM), SELENON (selenoprotein N, SEPN1, SELN), SELENOO (selenoprotein O, SELO), SELENOP (selenoprotein P, SeP, SEPP1, SELP), SELENOS (selenoprotein S, SELS, SEPS1, VIMP), SELENOT (selenoprotein T, SELT), SELENOV (selenoprotein V, SELV) and SELENOW (selenoprotein W, SELW, SEPW1). This system, approved by the HUGO Gene Nomenclature Committee, also resolves conflicting, missing and ambiguous designations for selenoprotein genes and is applicable to selenoproteins across vertebrates

    Contract Formation Jurisdiction of the United States Claims Court

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    This new United States Court of Appeals for the Federal Circuit has jurisdiction over appeals in contract and patent infringement cases. The former Court of Claims\u27 trial division has also been replaced with a new United States Claims Court. This court, inter alia, has been invested with the jurisdiction to conduct trials in contract and patent cases. Of particular interest to the government contracting community, is the provision of the Act regarding the contract formation or pre-award jurisdiction of the new Claims Court. The Claims Court has the potential to provide the most effective forum for the resolution of protests against the award of federal government contracts. Early decisions by the Claims Court defining both the court\u27s jurisdiction over pre-award issues and the scope of review in cases found to be within the court\u27s jurisdiction, however, raised substantial fears whether that potential ever would be reached. The March 23, 1983 decision of the new Court of Appeals for the Federal Circuit in United States v. Grimberg Co. and subsequent Claims Court opinions applying that decision now confirm those fears. Section I looks at the situation in government contracts cases before the creation of the new court. Section II briefly acknowledges the limitations of the former system, and how Congress sought to fix these problems in the Federal Courts Improvement Act. Then Section II turns to discuss the decision in US v. Grimberg
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