943 research outputs found

    Investigating powerful jets in radio-loud Narrow Line Seyfert 1s

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    We report results on multiband observations from radio to gamma-rays of the two radio-loud narrow-line Seyfert 1 (NLSy1) galaxies PKS 2004-447 and J1548+3511. Both sources show a core-jet structure on parsec scale, while they are unresolved at the arcsecond scale. The high core dominance and the high variability brightness temperature make these NLSy1 galaxies good gamma-ray source candidates. Fermi-LAT detected gamma-ray emission only from PKS 2004-447, with a gamma-ray luminosity comparable to that observed in blazars. No gamma-ray emission is observed for J1548+3511. Both sources are variable in X-rays. J1548+3511 shows a hardening of the spectrum during high activity states, while PKS 2004-447 has no spectral variability. A spectral steepening likely related to the soft excess is hinted below 2 keV for J1548+3511, while the X-ray spectra of PKS 2004-447 collected by XMM-Newton in 2012 are described by a single power-law without significant soft excess. No additional absorption above the Galactic column density or the presence of an Fe line is detected in the X-ray spectra of both sources.Comment: 16 pages, 8 figures, accepted for publication in MNRA

    A 10B-based neutron detector with stacked Multiwire Proportional Counters and macrostructured cathodes

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    We present the results of the measurements of the detection efficiency for a 4.7 \r{A} neutron beam incident upon a detector incorporating a stack of up to five MultiWire Proportional Counters (MWPC) with Boron-coated cathodes. The cathodes were made of Aluminum and had a surface exhibiting millimeter-deep V-shaped grooves of 45{\deg}, upon which the thin Boron film was deposited by DC magnetron sputtering. The incident neutrons interacting with the converter layer deposited on the sidewalls of the grooves have a higher capture probability, owing to the larger effective absorption film thickness. This leads to a higher overall detection efficiency for the grooved cathode when compared to a cathode with a flat surface. Both the experimental results and the predictions of the GEANT4 model suggests that a 5-counter detector stack with coated grooved cathodes has the same efficiency as a 7-counter stack with flat cathodes. The reduction in the number of counters in the stack without altering the detection efficiency will prove highly beneficial for large-area position-sensitive detectors for neutron scattering applications, for which the cost-effective manufacturing of the detector and associated readout electronics is an important objective. The proposed detector concept could be a technological option for one of the new chopper spectrometers and other instruments planned to be built at the future European Spallation Source in Sweden. These results with macrostructured cathodes generally apply not just to MWPCs but to other gaseous detectors as well.Comment: 14 pages, 9 figure

    Characterization of the Arterial Adventitia as a Sonic Hedgehog Responsive Niche

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    While formerly viewed as merely connective tissue, the emerging view of the arterial adventitia is that of a complex and organized vascular progenitor cell niche. Previously, our lab has identified a domain of Sonic Hedgehog (Shh) signaling restricted to the adventitia. This domain is locally produced and maintained, with the peak of activity being during embryonic and neonatal development of the vessel from embryonic day 14.5 (e14.5) to postnatal day 14 in the mouse. Developmental studies suggest that the mesenchyme continuous with the perichondrium of the axial skeleton contains Shh responsive cells that may contribute to adventitial development around e14.5. The cell types that participate in this Sonic Hedgehog adventitial signaling community are CD68-positive macrophages, Sca1-positive progenitor cells, and Perilipin A-positive adipocytes that make and/or respond to Shh protein as shown using transgenic reporter mice. Thus, we characterize the adventitia as a Shh responsive vascular niche

    DENSITÉ DES NIVEAUX DE BASSE ÉNERGIE ET INSTABILITÉS DE SURFACE DANS LES NOYAUX LOURDS DE TRANSITION

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    Une analyse statistique des niveaux nucléaires de Au, Pt, Hg a été réalisée avec la méthode d'Ericson. Les distributions expérimentales du nombre de niveaux d'or impair sont comparées aux distributions théoriques correspondant aux modèles vibrationnels (Alaga, Kisslinger-Sorensen) et rotationnels (Stephens, Meyer-ter-Vehn). Le modèle d'Alaga donne la description la plus complète des niveaux de 193,195Au et s'accorde avec la partie inférieure de la distribution de haute énergie de Gilbert-Cameron (déduite du modèle statistique et des données de capture neutronique). La méthode d'Ericson révèle d'autres aspects intéressants des isotopes de Pt et Hg (p. ex. dépendance entre la densité des niveaux et la forme des noyaux ou des corrélations de paires, évidence pour des transitions de phase). En conséquence, cette méthode est un outil approprié pour l'orientation des recherches expérimentales aussi bien que théoriques des noyaux de transition

    Neurochemical Aftermath of Repetitive Mild Traumatic Brain Injury

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    IMPORTANCE: Evidence is accumulating that repeated mild traumatic brain injury (mTBI) incidents can lead to persistent, long-term debilitating symptoms and in some cases a progressive neurodegenerative condition referred to as chronic traumatic encephalopathy. However, to our knowledge, there are no objective tools to examine to which degree persistent symptoms after mTBI are caused by neuronal injury. OBJECTIVE: To determine whether persistent symptoms after mTBI are associated with brain injury as evaluated by cerebrospinal fluid biochemical markers for axonal damage and other aspects of central nervous system injury. DESIGN, SETTINGS, AND PARTICIPANTS: A multicenter cross-sectional study involving professional Swedish ice hockey players who have had repeated mTBI, had postconcussion symptoms for more than 3 months, and fulfilled the criteria for postconcussion syndrome (PCS) according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) matched with neurologically healthy control individuals. The participants were enrolled between January 2014 and February 2016. The players were also assessed with Rivermead Post Concussion Symptoms Questionnaire and magnetic resonance imaging. MAIN OUTCOMES AND MEASURES: Neurofilament light protein, total tau, glial fibrillary acidic protein, amyloid β, phosphorylated tau, and neurogranin concentrations in cerebrospinal fluid. RESULTS: A total of 31 participants (16 men with PCS; median age, 31 years; range, 22-53 years; and 15 control individuals [11 men and 4 women]; median age, 25 years; range, 21-35 years) were assessed. Of 16 players with PCS, 9 had PCS symptoms for more than 1 year, while the remaining 7 returned to play within a year. Neurofilament light proteins were significantly increased in players with PCS for more than 1 year (median, 410 pg/mL; range, 230-1440 pg/mL) compared with players whose PCS resolved within 1 year (median, 210 pg/mL; range, 140-460 pg/mL) as well as control individuals (median 238 pg/mL, range 128-526 pg/mL; P = .04 and P = .02, respectively). Furthermore, neurofilament light protein concentrations correlated with Rivermead Post Concussion Symptoms Questionnaire scores and lifetime concussion events (ρ = 0.58, P = .02 and ρ = 0.52, P = .04, respectively). Overall, players with PCS had significantly lower cerebrospinal fluid amyloid-β levels compared with control individuals (median, 1094 pg/mL; range, 845-1305 pg/mL; P = .05). CONCLUSIONS AND RELEVANCE: Increased cerebrospinal fluid neurofilament light proteins and reduced amyloid β were observed in patients with PCS, suggestive of axonal white matter injury and amyloid deposition. Measurement of these biomarkers may be an objective tool to assess the degree of central nervous system injury in individuals with PCS and to distinguish individuals who are at risk of developing chronic traumatic encephalopathy

    Exploring research participants' perceptions of cardiovascular risk information-Room for improvement and empowerment

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    Objective The objective of this study was to explore research participants’ (adults, age 50–65) perceptions of receiving cardiovascular risk information. Methods Five focus group interviews (N = 31) were performed with research participants aged 50–65 who participated in the Swedish CArdioPulmonary BioImage Study (SCAPIS). The interviews were analyzed using qualitative content analysis. Results The categories;

    Inteelt onder Sallandse korhoenders : de genetische gevolgen van een kleine populatieomvang

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    Recent werd Alterra gevraagd om de resultaten van onderzoek dat de afgelopen jaren door verschillende instituten is uitgevoerd te bundelen en te integreren om een antwoord te krijgen op de vraag of het korhoen duurzaam voor Nederland behouden kan worden en op welke manier behoud mogelijk is (Jansman et al. 2014). Het voorliggende rapport is een aanvulling op dit basisrapport, waarin dieper wordt ingegaan op de effecten die de sterke afname in populatieomvang heeft gehad op het verloop van genetische processen van de korhoenpopulatie, en de gevolgen die dit kan hebben voor de algehele vitaliteit van de populatie, en diens reproductievermogen in het bijzonder. In dit onderzoek is duidelijk geworden dat de Nederlandse korhoenpopulatie al in 2010 genetisch zeer sterk was verarmd. In 2013, toen slechts zeven individuen overgebleven waren, bleek de variatie nog verder teruggelopen, ook op genen die van belang zijn voor een goed functionerend immuunsystee
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