229 research outputs found
ARIADNE - A novel optical LArTPC: technical design report and initial characterisation using a secondary beam from the CERN PS and cosmic muons
ARIADNE is a 1-ton (330 kg fiducial mass) dual-phase liquid argon (LAr) time
projection chamber (TPC) featuring a novel optical readout. Four
electron-multiplying charge-coupled device (EMCCD) cameras are mounted
externally, and these capture the secondary scintillation light produced in the
holes of a thick electron gas multiplier (THGEM). Track reconstruction using
this novel readout approach is demonstrated. Optical readout has the potential
to be a cost effective alternative to charge readout in future LArTPCs. In this
paper, the technical design of the detector is detailed. Results of mixed
particle detection using a secondary beam from the CERN PS (representing the
first ever optical images of argon interactions in a dual-phase LArTPC at a
beamline) and cosmic muon detection at the University of Liverpool are also
presented.Comment: 58 pages, 40 figures. Changes from previous version based on
pre-publication review: improved quality of various figures, improved clarity
of some definitions and reduced longer sentences for better readability,
fixed typos and formatting error
The influence of socio-demographic, psychological and knowledge-related variables alongside perceived cooking and food skills abilities in the prediction of diet quality in adults: a nationally representative cross-sectional study
Background: Interventions to increase cooking skills (CS) and food skills (FS) as a route to improving overall diet are popular within public health. This study tested a comprehensive model of diet quality by assessing the influence of socio-demographic, knowledge- and psychological-related variables alongside perceived CS and FS abilities. The correspondence of two measures of diet quality further validated the Eating Choices Index (ECI) for use in quantitative research.Methods: A cross-sectional survey was conducted in a quota-controlled nationally representative sample of 1049 adults aged 20â60 years drawn from the Island of Ireland. Surveys were administered in participantsâ homes via computer-assisted personal interviewing (CAPI) assessing a range of socio-demographic, knowledge- and psychological-related variables alongside perceived CS and FS abilities. Regression models were used to model factors influencing diet quality. Correspondence between 2 measures of diet quality was assessed using chi-square and Pearson correlations.Results: ECI score was significantly negatively correlated with DINE Fat intake (r = -0.24, p < 0.001), and ECI score was significantly positively correlated with DINE Fibre intake (r = 0.38, p < 0.001), demonstrating a high agreement. Findings indicated that males, younger respondents and those with no/few educational qualifications scored significantly lower on both CS and FS abilities. The relative influence of socio-demographic, knowledge, psychological variables and CS and FS abilities on dietary outcomes varied, with regression models explaining 10â20 % of diet quality variance. CS ability exerted the strongest relationship with saturated fat intake (ÎČ = -0.296, p < 0.001) and was a significant predictor of fibre intake (ÎČ = -0.113, p < 0.05), although not for healthy food choices (ECI) (ÎČ = 0.04, p > 0.05).Conclusion: Greater CS and FS abilities may not lead directly to healthier dietary choices given the myriad of other factors implicated; however, CS appear to have differential influences on aspects of the diet, most notably in relation to lowering saturated fat intake. Findings suggest that CS and FS should not be singular targets of interventions designed to improve diet; but targeting specific sub-groups of the population e.g. males, younger adults, those with limited education might be more fruitful. A greater understanding of the interaction of factors influencing cooking and food practices within the home is needed
Line emission from optically thick relativistic accretion tori
We calculate line emission from relativistic accretion tori around Kerr black
holes and investigate how the line profiles depend on the viewing inclination,
spin of the central black hole, parameters describing the shape of the tori,
and spatial distribution of line emissivity on the torus surface. We also
compare the lines with those from thin accretion disks. Our calculations show
that lines from tori and lines from thin disks share several common features.
In particular, at low and moderate viewing inclination angles they both have
asymmetric double-peaked profiles with a tall, sharp blue peak and a shorter
red peak which has an extensive red wing. At high viewing inclination angles
they both have very broad, asymmetric lines which can be roughly considered
single-peaked. Torus and disk lines may show very different red and blue line
wings, but the differences are due to the models for relativistic tori and
disks having differing inner boundary radii. Self-eclipse and lensing play some
role in shaping the torus lines, but they are effective only at high
inclination angles. If inner and outer radii of an accretion torus are the same
as those of an accretion disk, their line profiles show substantial differences
only when inclination angles are close to 90 degrees, and those differences
manifest mostly at the central regions of the lines instead of the wings.Comment: 14 pages, 17 figures. Accepted to A&
The instrumental polarization of the Nasmyth focus polarimetric differential imager NAOS/CONICA (NACO) at the VLT - Implications for time-resolved polarimetric measurements of Sgr A*
We report on the results of calibrating and simulating the instrumental
polarization properties of the ESO VLT adaptive optics camera system
NAOS/CONICA (NACO) in the Ks-band. We use the Stokes/Mueller formalism for
metallic reflections to describe the instrumental polarization. The model is
compared to standard-star observations and time-resolved observations of bright
sources in the Galactic center. We find the instrumental polarization to be
highly dependent on the pointing position of the telescope and about 4% at
maximum. We report a polarization angle offset of 13.28{\deg} due to a position
angle offset of the half-wave plate that affects the calibration of NACO data
taken before autumn 2009. With the new model of the instrumental polarization
of NACO it is possible to measure the polarization with an accuracy of 1% in
polarization degree. The uncertainty of the polarization angle is < 5{\deg} for
polarization degrees > 4%. For highly sampled polarimetric time series we find
that the improved understanding of the polarization properties gives results
that are fully consistent with the previously used method to derive the
polarization. The small difference between the derived and the previously
employed polarization calibration is well within the statistical uncertainties
of the measurements, and for Sgr A* they do not affect the results from our
relativistic modeling of the accretion process.Comment: 16 pages, 15 figures, 5 tables, accepted by A&A on 2010 October 1
Near-infrared polarimetry setting constraints on the orbiting spot model for Sgr A* flares
Context: Recent near-infrared polarization measurements of SgrA* show that
its emission is significantly polarized during flares and consists of a non- or
weakly polarized main flare with highly polarized sub-flares. The flare
activity suggests a quasi-periodicity of ~20 minutes in agreement with previous
observations. Aims: By simultaneous fitting of the lightcurve fluctuations and
the time-variable polarization angle, we address the question of whether these
changes are consistent with a simple hot spot/ring model, in which the
interplay of relativistic effects plays the major role, or whether some more
complex dependency of the intrinsic emissivity is required. Methods: We discuss
the significance of the 20min peak in the periodogram of a flare from 2003. We
consider all general relativistic effects that imprint on the polarization
degree and angle and fit the recent polarimetric data, assuming that the
synchrotron mechanism is responsible for the intrinsic polarization and
considering two different magnetic field configurations. Results: Within the
quality of the available data, we think that the model of a single spot in
addition to an underlying ring is favoured. In this model the broad
near-infrared flares of Sgr A* are due to a sound wave that travels around the
MBH once while the sub-flares, superimposed on the broad flare, are due to
transiently heated and accelerated electrons which can be modeled as a plasma
blob. Within this model it turns out that a strong statement about the spin
parameter is difficult to achieve, while the inclination can be constrained to
values > 35 deg on a 3sigma level.Comment: accepted by A&A for publicatio
Validating differential volatilome profiles in Parkinsonâs disease
Contains fulltext :
231972.pdf (Publisherâs version ) (Open Access
Vasodilation of rat skeletal muscle arteries by the novel BK channel opener GoSlo is mediated by the simultaneous activation of BK and Kv7 channels
BACKGROUND AND PURPOSE: BK channels play important roles in various physiological and pathophysiological processes and thus have been the target of several drug development programs focused on creating new efficacious BK channel openers, such as the GoSlo-SR compounds. However, the effect of GoSlo-SR compounds on vascular smooth muscle has not been studied. Therefore, we tested the hypothesis that GoSlo-SR compounds dilate arteries exclusively by activating BK channels. EXPERIMENTAL APPROACH: Experiments were performed on rat Gracilis muscle, saphenous, mesenteric and tail arteries using isobaric and isometric myography, sharp microelectrodes, digital droplet PCR and the patch-clamp technique. KEY RESULTS: GoSlo-SR compounds dilated isobaric and relaxed and hyperpolarized isometric vessel preparations and their effects were abolished after (i) functionally eliminating K channels by pre-constriction with 50 mM KCl or (ii) blocking all K channels known to be expressed in vascular smooth muscle. However, these effects were not blocked when BK channels were inhibited. Surprisingly, the K(V)7 channel inhibitor XE991 reduced their effects considerably, but neither K(V)1 nor K(V)2 channel blockers altered the inhibitory effects of GoSlo-SR. However, the combined blockade of BK and K(V)7 channels abolished the GoSlo-SR-induced relaxation. GoSlo-SR compounds also activated K(V)7.4 and K(V)7.5 channels expressed in HEK 293 cells. CONCLUSIONS AND IMPLICATIONS: This study shows that GoSlo-SR-compounds are effective relaxants in vascular smooth muscle and mediate their effects by a combined activation of BK and K(V)7.4/K(V)7.5 channels. Activation of K(V)1, K(V)2 or K(V)7.1 channels or other vasodilator pathways seem not to be involved
Near infrared flares of Sagittarius A*: Importance of near infrared polarimetry
We report on the results of new simulations of near-infrared (NIR)
observations of the Sagittarius A* (Sgr A*) counterpart associated with the
super-massive black hole at the Galactic Center. The observations have been
carried out using the NACO adaptive optics (AO) instrument at the European
Southern Observatory's Very Large Telescope and CIAO NIR camera on the Subaru
telescope (13 June 2004, 30 July 2005, 1 June 2006, 15 May 2007, 17 May 2007
and 28 May 2008). We used a model of synchrotron emission from relativistic
electrons in the inner parts of an accretion disk. The relativistic simulations
have been carried out using the Karas-Yaqoob (KY) ray-tracing code. We probe
the existence of a correlation between the modulations of the observed flux
density light curves and changes in polarimetric data. Furthermore, we confirm
that the same correlation is also predicted by the hot spot model. Correlations
between intensity and polarimetric parameters of the observed light curves as
well as a comparison of predicted and observed light curve features through a
pattern recognition algorithm result in the detection of a signature of
orbiting matter under the influence of strong gravity. This pattern is detected
statistically significant against randomly polarized red noise. Expected
results from future observations of VLT interferometry like GRAVITY experiment
are also discussed.Comment: 26 pages, 38 figures, accepted for publication by A&
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