943 research outputs found
Investigating powerful jets in radio-loud Narrow Line Seyfert 1s
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
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Interface Stability During Rapid Directional Solidification
Engineering and Applied Science
A 10B-based neutron detector with stacked Multiwire Proportional Counters and macrostructured cathodes
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
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
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
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Knowledge management infrastructure to support quality improvement: A qualitative study of maternity services in four European hospitals
The influence of multilevel healthcare system interactions on clinical quality improvement (QI) is still largely unexplored. Through the lens of knowledge management (KM) theory, this study explores how hospital managers can enhance the conditions for clinical QI given the specific multilevel and professional interactions in various healthcare systems.
The research used an in-depth multilevel analysis in maternity departments in four purposively sampled European hospitals (Portugal, England, Norway and Sweden). The study combines analysis of macro-level policy documents and regulations with semi-structured interviews (96) and non-participant observations (193 hours) of hospital and clinical managers and clinical staff in maternity departments.
There are four main conclusions: First, the unique multilevel configuration of national healthcare policy, hospital management and clinical professionals influence the development of clinical QI efforts. Second, these different configurations provide various and often insufficient support and guidance which affect professionals’ action strategies in QI efforts. Third, hospital managers’ opportunities and capabilities for developing a consistent KM infrastructure with reinforcing enabling conditions which merge national policies and guidelines with clinical reality is crucial for clinical QI. Fourth, understanding these interrelationships provides an opportunity for improvement of the KM infrastructure for hospital managers through tailored interventions
Neurochemical Aftermath of Repetitive Mild Traumatic Brain Injury
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
Weight gain and resistance to gastrointestinal nematode infections in two genetically diverse groups of cattle
Exploring research participants' perceptions of cardiovascular risk information-Room for improvement and empowerment
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
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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