49 research outputs found

    A radio and infrared exploration of the Cygnus X-3 environments

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    To confirm, or rule out, the possible hot spot nature of two previously detected radio sources in the vicinity of the Cygnus X-3 microquasar. We present the results of a radio and near infrared exploration of the several arc-minute field around the well known galactic relativistic jet source Cygnus X-3 using the Very Large Array and the Calar Alto 3.5~m telescope. The data this paper is based on do not presently support the hot spot hypothesis. Instead, our new observations suggest that these sources are most likely background or foreground objects. Actually, none of them appears to be even barely extended as would be expected if they were part of a bow shock structure. Our near infrared observations also include a search for extended emission in the Bracket γ\gamma (2.166 μ\mum) and H2H_{2} (2.122 μ\mum) lines as possible tracers of shocked gas in the Cygnus X-3 surroundings. The results were similarly negative and the corresponding upper limits are reported.Comment: Accepted for publication in A&A; 5 pages, 4 figure

    Chandra X-ray counterpart of KS 1741-293

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    We aim to investigate the nature of the high energy source KS 1741-293 by revisiting the radio and infrared associations proposed in the early 1990s. Our work is mostly based on the analysis of modern survey and archive data, including the NRAO, MSX, 2MASS and Chandra archives, and catalogues. We also have obtained deep CCD optical observations by ourselves. The coincidence of KS 1741-293 with an extended radio and far-infrared source, tentatively suggested in 1994, is no longer supported by modern observational data. Instead, a Chandra source is the only peculiar object found to be consistent with all high-energy error circles of KS 1741-293 and we propose it to be its most likely X-ray counterpart. We also report the existence of a non-thermal radio nebula in the vicinity of the KS 1741-293 position with the appearance of a supernova remnant. The possibility of being associated to this X-ray binary is discussed.Comment: 5 pages, 4 figures, 2 tables. Accepted for publication in Astronomy & Astrophysic

    An X-ray study of the SNR G344.7-0.1 and the central object CXOU J170357.8-414302

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    Aims. We report results of an X-ray study of the supernova remnant (SNR) G344.7-0.1 and the point-like X-ray source located at the geometrical center of the SNR radio structure. Methods. The morphology and spectral properties of the remnant and the central X-ray point-like source were studied using data from the XMM-Newton and Chandra satellites. Archival radio data and infrared Spitzer observations at 8 and 24 μ\mum were used to compare and study its multi-band properties at different wavelengths. Results. The XMM-Newton and Chandra observations reveal that the overall X-ray emission of G344.7-0.1 is extended and correlates very well with regions of bright radio and infrared emission. The X-ray spectrum is dominated by prominent atomic emission lines. These characteristics suggest that the X-ray emission originated in a thin thermal plasma, whose radiation is represented well by a plane-parallel shock plasma model (PSHOCK). Our study favors the scenario in which G344.7-0.1 is a 6 x 10^3 year old SNR expanding in a medium with a high density gradient and is most likely encountering a molecular cloud on the western side. In addition, we report the discovery of a soft point-like X-ray source located at the geometrical center of the radio SNR structure. The object presents some characteristics of the so-called compact central objects (CCO). However, its neutral hydrogen absorption column (N_{H}) is inconsistent with that of the SNR. Coincident with the position of the source, we found infrared and optical objects with typical early-K star characteristics. The X-ray source may be a foreground star or the CCO associated with the SNR. If this latter possibility were confirmed, the point-like source would be the farthest CCO detected so far and the eighth member of the new population of isolated and weakly magnetized neutron stars.Comment: 9 pages, 8 figures, accepted for publication in Astronomy and Astrophysics. Higher resolution figures can be seen on A&

    Modeling of pv module and dc/dc converter assembly for the analysis of induced transient response due to nearby lightning strike

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    Photovoltaic (PV) systems are subject to nearby lightning strikes that can contribute to extremely high induced overvoltage transients. Recently, the authors introduced a 3D semi-analytical method to study the electromagnetic transients caused by these strikes in a PV module. In the present paper we develop an improved model of the PV module that: (a) takes into account high-frequency effects by modelling capacitive and inductive couplings; (b) considers the electrical insulation characteristics of the module; (c) includes the connection to a DC/DC converter. The whole process involves three major steps, i.e., the magnetic-field computation, the evaluation of both common-mode-and differential-mode-induced voltages across the PV module, and the use of the calculated voltages as input to a lumped equivalent circuit of the PV module connected to the DC/DC converter. In such a framework, the influence of the PV operating condition on the resulting electrical stresses is assessed; moreover, the relevance or insignificance of some parameters, such as the module insulation or the frame material, is demonstrated. Finally, results show that the induced overvoltage are highly dependent both on the grounding of the conducting parts and on the external conditions such as lightning current waveforms and lightning channel (LC) geometry

    Modeling of pv module and dc/dc converter assembly for the analysis of induced transient response due to nearby lightning strike

    Get PDF
    Photovoltaic (PV) systems are subject to nearby lightning strikes that can contribute to extremely high induced overvoltage transients. Recently, the authors introduced a 3D semi-analytical method to study the electromagnetic transients caused by these strikes in a PV module. In the present paper we develop an improved model of the PV module that: (a) takes into account high-frequency effects by modelling capacitive and inductive couplings; (b) considers the electrical insulation characteristics of the module; (c) includes the connection to a DC/DC converter. The whole process involves three major steps, i.e., the magnetic-field computation, the evaluation of both common-mode-and differential-mode-induced voltages across the PV module, and the use of the calculated voltages as input to a lumped equivalent circuit of the PV module connected to the DC/DC converter. In such a framework, the influence of the PV operating condition on the resulting electrical stresses is assessed; moreover, the relevance or insignificance of some parameters, such as the module insulation or the frame material, is demonstrated. Finally, results show that the induced overvoltage are highly dependent both on the grounding of the conducting parts and on the external conditions such as lightning current waveforms and lightning channel (LC) geometry

    Analysis of the Attitudes towards Sexuality in People with Intellectual Disabilities: A Cross-Sectional Study

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    The barriers faced by people with intellectual disabilities are many. One of the areas in which many problems have been identified is the sexual domain. This descriptive study aims to analyze the attitudes of the family environment, professional carers, and the general population toward their sexuality. A cross-sectional descriptive study was carried out between 2022 and 2023, using convenience sampling among family members and carers from different centers working with people with intellectual disabilities in Spain, and among the general population not related to people with intellectual disabilities. A total of 583 responses were received and significant differences were found for all variables, with the variables related to family or work proximity being those that provided the most significant and relevant results. It was observed that the male sex has a more paternalistic attitude and that in rural areas there is a more permissive attitude towards the sexuality of people with intellectual disabilities. People who work with people with disabilities have more positive attitudes towards this group, while direct relatives have more paternalistic attitudes. Nursing care in the community and specialized centers should be based on an adequate therapeutic relationship and personalized care

    X-ray Identifications of FIRST Radio Sources in the xBootes Field

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    With the goal of investigating the nature and the environment of the faint radio sources (at mJy level), here are presented results of X-ray dentifications of Faint Imaging Radio Survey at Twenty centimetres (FIRST) in the 9 square degrees Bootes field of the NOAO Deep Wide Field Survey (NDWFS), using data from the Chandra XBootes survey. A total of 92 (10%) FIRST radio sources are identified above the X-ray flux limit f_X (0.5-7) keV = 8x10^{-15} erg s^{-1} cm^{-2}, and 79 optical counterparts are common to both the radio and X-ray sources. Spectroscopic identifications were available for 22 sources (27%). Multi-wavelength optical/infrared photometric data (Bw~25.5 mag, R~25.8 mag, I~25.5 mag and K~19.4 mag) were available for this field and were used to derive photometric redshift for the remaining 57 sources without spectroscopic information. Most of the radio-X-ray matches are optically extended objects in the R band with a photometric redshift distribution peaking at z~0.7. Based on the hardness ratio and X-ray luminosity, 37 sources (89%) were classified as AGN-1, 19 as AGN-2, 12 as QSO-1, 2 as QSO-2 and 9 sources as normal galaxies. While the majority of these sources have a hard X-ray luminosity L_X(2-7) keV >10^{42} erg s^{-1}, about one third of the sources have L_X(2-7) keV >10^{44} erg s^{-1} and therefore classified as QSO-1. The majority (68%) of the radio-X-ray matched population are found to have -1<log l_X/f_opt<1, region indicative of AGNs, 23% with high X-ray-to-optical flux ratio (log f_X/f_opt > 1), suggesting high redshift and/or dust obscured AGN, and 11% of the radio-X-ray matches that are X-ray faint optically bright sources with log f_X/f_opt <-1, and most of these sources are optically extended. These objects are low-z, normal galaxies or low luminosity AGNs (LINERS).Comment: 29 pages, 19 figures and 1 table. Accepted for publication in MNRA

    Bacterial laccases: some recent advances and applications

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    Laccases belong to the large family of multi-copper oxidases (MCOs) that couple the one-electron oxidation of substrates with the four-electron reduction of molecular oxygen to water. Because of their high relative non-specific oxidation capacity particularly on phenols and aromatic amines as well as the lack of requirement for expensive organic cofactors, they have found application in a large number of biotechnological fields. The vast majority of studies and applications were performed using fungal laccases, but bacterial laccases show interesting properties such as optimal temperature above 50 °C, optimal pH at the neutral to alkaline range, thermal and chemical stability and increased salt tolerance. Additionally, bacterial systems benefit from a wide range of molecular biology tools that facilitates their engineering and achievement of high yields of protein production and set-up of cost-effective bioprocesses. In this review we will provide up-to-date information on the distribution and putative physiological role of bacterial laccases and highlight their distinctive structural and biochemical properties, discuss the key role of copper in the biochemical properties, discuss thermostability determinants and, finally, review biotechnological applications with a focus on catalytic mechanisms on phenolics and aromatic amines.info:eu-repo/semantics/publishedVersio

    Mapping European Association of Urology Guideline Practice Across Europe: An Audit of Androgen Deprivation Therapy Use Before Prostate Cancer Surgery in 6598 Cases in 187 Hospitals Across 31 European Countries

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    Background: Evidence-practice gaps exist in urology. We previously surveyed European Association of Urology (EAU) guidelines for strong recommendations underpinned by high-certainty evidence that impact patient experience for which practice variations were suspected. The recommendation “Do not offer neoadjuvant androgen deprivation therapy (ADT) before surgery for patients with prostate cancer” was prioritised for further investigation. ADT before surgery is neither clinically effective nor cost effective and has serious side effects. The first step in improving implementation problems is to understand their extent. A clear picture of practice regarding ADT before surgery across Europe is not available. Objective: To assess current ADT use before prostate cancer surgery in Europe. Design, setting, and participants: This was an observational cross-sectional study. We retrospectively audited recent ADT practices in a multicentre international setting. We used nonprobability purposive sampling, aiming for breadth in terms of low- versus high-volume, academic, versus community and public versus private centres. Outcome measurements and statistical analysis: Our primary outcome was adherence to the ADT recommendation. Descriptive statistics and a multilevel model were used to investigate differences between countries across different factors (volume, centre type, and funding type). Subgroup analyses were performed for patients with low, intermediate, and high risk, and for those with locally advanced prostate cancer. We also collected reasons for nonadherence. Results and limitations: We included 6598 patients with prostate cancer from 187 hospitals in 31 countries from January 1, 2017 to May 1, 2020. Overall, nonadherence was 2%, (range 0–32%). Most of the variability was found in the high-risk subgroup, for which nonadherence was 4% (range 0–43%). Reasons for nonadherence included attempts to improve oncological outcomes or preoperative tumour parameters; attempts to control the cancer because of long waiting lists; and patient preference (changing one's mind from radiotherapy to surgery after neoadjuvant ADT had commenced or feeling that the side effects were intolerable). Although we purposively sampled for variety within countries (public/private, academic/community, high/low-volume), a selection bias toward centres with awareness of guidelines is possible, so adherence rates may be overestimated. Conclusions: EAU guidelines recommend against ADT use before prostate cancer surgery, yet some guideline-discordant ADT use remains at the cost of patient experience and an additional payer and provider burden. Strategies towards discontinuation of inappropriate preoperative ADT use should be pursued. Patient summary: Androgen deprivation therapy (ADT) is sometimes used in men with prostate cancer who will not benefit from it. ADT causes side effects such as weight gain and emotional changes and increases the risk of cardiovascular disease, diabetes, and osteoporosis. Guidelines strongly recommend that men opting for surgery should not receive ADT, but it is unclear how well the guidance is followed. We asked urologists across Europe how patients in their institutions were treated over the past few years. Most do not use ADT before surgery, but this still happens in some places. More research is needed to help doctors to stop using ADT in patients who will not benefit from it
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