236 research outputs found

    A new perspective on GCRT J1745-3009

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    Two WSRT observations were performed and five archival VLA data were reduced in order to redetect the enigmatic radio transient GCRT J1745-3009. The source was not redetected. We were, however, able to extract important new information from the discovery dataset. Our reanalysis excludes models that predict symmetric bursts, but the transient white dwarf pulsar is favoured. Although we now have more contraints on the properties of this source, we are still unsure about its basic model.Comment: 11 pages, 5 figure

    Autologous lipoaspirate as a new treatment of vulvar lichen sclerosus:A review on literature

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    Lichen sclerosus (LS) is a chronic inflammatory dermatosis that mostly affects the genital and anal skin areas. Symptoms may vary from pruritis and pain to sexual dysfunction; however, LS can also be asymptomatic. LS occurs at all ages and in both sexes. Approximately 5% of all women affected by vulvar LS will develop vulvar squamous cell carcinoma. Topical treatment is safe but less effective resulting in chronic course in most patients, who suffer from persistent itching and pain. In severe cases of therapy-resistant LS, there is no adequate treatment. Fat grafting is a novel regenerative therapy to reduce dermal fibrosis. The therapeutic effect of adipose tissue grafts for LS is already investigated in various pioneering studies. This review provides an overview of these studies and the putative mechanisms-of-action of fat grafting to treat LS

    Detailed study of the GRB 030329 radio afterglow deep into the non-relativistic phase

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    We explore the physics behind one of the brightest radio afterglows ever, GRB 030329, at late times when the jet is non-relativistic. We determine the physical parameters of the blast wave and its surroundings, in particular the index of the electron energy distribution, the energy of the blast wave, and the density (structure) of the circumburst medium. We then compare our results with those from image size measurements. We observed the GRB 030329 radio afterglow with the Westerbork Synthesis Radio Telescope and the Giant Metrewave Radio Telescope at frequencies from 325 MHz to 8.4 GHz, spanning a time range of 268-1128 days after the burst. We modeled all the available radio data and derived the physical parameters. The index of the electron energy distribution is p=2.1, the circumburst medium is homogeneous, and the transition to the non-relativistic phase happens at t_NR ~ 80 days. The energy of the blast wave and density of the surrounding medium are comparable to previous findings. Our findings indicate that the blast wave is roughly spherical at t_NR, and they agree with the implications from the VLBI studies of image size evolution. It is not clear from the presented dataset whether we have seen emission from the counter jet or not. We predict that the Low Frequency Array will be able to observe the afterglow of GRB 030329 and many other radio afterglows, constraining the physics of the blast wave during its non-relativistic phase even further.Comment: 9 pages, 2 figures; accepted for publication in Astronomy & Astrophysics after minor revisions; small changes in GMRT fluxes at 1280 MH

    An automated archival VLA transients survey

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    In this paper we present the results of a survey for radio transients using data obtained from the Very Large Array archive. We have reduced, using a pipeline procedure, 5037 observations of the most common pointings - i.e. the calibrator fields. These fields typically contain a relatively bright point source and are used to calibrate 'target' observations: they are therefore rarely imaged themselves. The observations used span a time range ˜1984-2008 and consist of eight different pointings, three different frequencies (8.4, 4.8 and 1.4 GHz) and have a total observing time of 435 h. We have searched for transient and variable radio sources within these observations using components from the prototype LOFAR transient detection system. In this paper we present the methodology for reducing large volumes of Very Large Array data; and we also present a brief overview of the prototype LOFAR transient detection algorithms. No radio transients were detected in this survey, therefore we place an upper limit on the snapshot rate of GHz frequency transients >8.0 mJy to ρ≤ 0.032 deg-2 that have typical time-scales 4.3 to 45.3 d. We compare and contrast our upper limit with the snapshot rates - derived from either detections or non-detections of transient and variable radio sources - reported in the literature. When compared with the current Log N-Log S distribution formed from previous surveys, we show that our upper limit is consistent with the observed population. Current and future radio transient surveys will hopefully further constrain these statistics, and potentially discover dominant transient source populations. In this paper we also briefly explore the current transient commissioning observations with LOFAR, and the impact they will make on the field

    EUV spectroscopy of highly charged Sn13+-Sn15+ ions in an electron-beam ion trap

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    Extreme-ultraviolet (EUV) spectra of Sn13+-Sn15+ ions have been measured in an electron-beam ion trap (EBIT). A matrix inversion method is employed to unravel convoluted spectra from a mixture of charge states typically present in an EBIT. The method is benchmarked against the spectral features of resonance transitions in Sn13+ and Sn14+ ions. Three new EUV lines in Sn14+ confirm its previously established level structure. This ion is relevant for EUV nanolithography plasma but no detailed experimental data currently exist. We used the Cowan code for first line identifications and assignments in Sn15+. The collisional-radiative modeling capabilities of the Flexible Atomic Code were used to include line intensities in the identification process. Using the 20 lines identified, we have established 17 level energies of the 4p44d configuration as well as the fine-structure splitting of the 4p5 ground-state configuration. Moreover, we provide state-of-the-art ab initio level structure calculations of Sn15+ using the configuration-interaction many-body perturbation code ambit. We find that the here-dominant emission features from the Sn15+ ion lie in the narrow 2% bandwidth around 13.5 nm that is relevant for plasma light sources for state-of-the-art nanolithography

    An automated archival VLA transients survey

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    In this paper we present the results of a survey for radio transients using data obtained from the Very Large Array archive. We have reduced, using a pipeline procedure, 5037 observations of the most common pointings - i.e. the calibrator fields. These fields typically contain a relatively bright point source and are used to calibrate `target' observations: they are therefore rarely imaged themselves. The observations used span a time range ~ 1984 - 2008 and consist of eight different pointings, three different frequencies (8.4, 4.8 and 1.4 GHz) and have a total observing time of 435 hours. We have searched for transient and variable radio sources within these observations using components from the prototype LOFAR transient detection system. In this paper we present the methodology for reducing large volumes of Very Large Array data; and we also present a brief overview of the prototype LOFAR transient detection algorithms. No radio transients were detected in this survey, therefore we place an upper limit on the snapshot rate of GHz frequency transients > 8.0 mJy to rho less than or equal to 0.032 deg^-2 that have typical timescales 4.3 to 45.3 days. We compare and contrast our upper limit with the snapshot rates - derived from either detections or non-detections of transient and variable radio sources - reported in the literature. When compared with the current Log N - Log S distribution formed from previous surveys, we show that our upper limit is consistent with the observed population. Current and future radio transient surveys will hopefully further constrain these statistics, and potentially discover dominant transient source populations. In this paper we also briefly explore the current transient commissioning observations with LOFAR, and the impact they will make on the field.Comment: Accepted for publication in MNRA

    Attaching metabolic expenditures to standard occupational classification systems: perspectives from time-use research

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    Abstract Background Traditionally, time-use data have been used to inform a broad range of economic and sociological research topics. One of the new areas in time-use research is the study of physical activity (PA) and physical activity energy expenditure (PAEE). Time-use data can be used to study PAEE by assigning MET values to daily activities using the Ainsworth Compendium of Physical Activities. Although most diarists record their daily activities accurately and in detail, they are only required to record their paid working hours, not the job-specific tasks they undertake. This makes it difficult to assign MET values to paid work episodes. Methods In this methodological paper, we explain how we addressed this problem by using the detailed information about respondents’ occupational status included in time-use survey household and individual questionnaires. We used the 2008 ISCO manual, a lexicon of the International Labour Organization of occupational titles and their related job-specific tasks. We first assigned a MET value to job-specific tasks using the Ainsworth compendium (2011) then calculated MET values for each of the 436 occupations in the ISCO-08 manual by averaging all job-specific MET values for each occupation. Results The ISCO-08 Major Groups of ‘elementary occupations’ and ‘craft and related trades workers’ are associated with high PAEE variation in terms of their job-specific MET values and together represented 21.6% of the Belgian working population in 2013. We recommend that these occupational categories should be prioritised for further in-depth research into occupational activity (OA). Conclusions We developed a clear and replicable procedure to calculate occupational activity for all ISCO-08 occupations. All of our calculations are attached to this manuscript which other researchers may use, replicate and refine
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