2,489 research outputs found
Orbital inflammatory complications of Crohn’s disease: a rare case series
Orbital inflammatory disease is a rare ophthalmic manifestation of Crohn’s disease. Inflammation is characteristically non-specific, involving one or multiple structures of the orbit. Mechanisms of disease and optimal methods of treatment are poorly understood. The aim of this report is to present three cases of orbital involvement in Crohn’s disease. A retrospective case note review of patients with orbital inflammatory disease and Crohn’s disease was performed at our academic centre to determine the clinical, imaging and histopathological features of this condition and its relationship to intestinal Crohn’s disease.
Three patients were identified with orbital inflammatory manifestations complicating Crohn’s disease. All patients described were female with active intestinal disease and had a history of treatment with immunosuppressive therapies. Similarities were observed in clinical presentations with variance noted in radiological and histopathological findings. In all cases, symptoms improved with oral corticosteroids or non-steroidal drugs in combination with anti-tumour necrosis factor (anti-TNF) agents. Inflammatory bowel disease-related orbital complications are rare but potentially vision-threatening. It is important to consider mimics of orbital inflammatory disease such as systemic inflammatory disease, malignancy, congenital malformations, infection and trauma when formulating a comprehensive differential diagnosis. Therapeutic intervention is directed towards preservation of vision and orbital function and reducing the acute inflammatory process. Corticosteroids are typically the initial treatment of choice for moderate-to-severe disease, although several classes of immunomodulatory agents have been variably useful in treating this condition. Heightened awareness and close cooperation between gastroenterologists and ophthalmologists is mandatory
Convergent evolution of sodium ion selectivity in metazoan neuronal signaling
© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Cell Reports 2 (2012): 242–248, doi:10.1016/j.celrep.2012.06.016.Ion selectivity of metazoan voltage-gated Na+ channels is critical for neuronal signaling and has long been attributed to a ring of four conserved amino acids that constitute the ion selectivity filter (SF) at the channel pore. Yet, in addition to channels with a preference for Ca2+ ions, the expression and characterization of Na+ channel homologs from the sea anemone Nematostella vectensis, a member of the early-branching metazoan phylum Cnidaria, revealed a sodium-selective channel bearing a noncanonical SF. Mutagenesis and physiological assays suggest that pore elements additional to the SF determine the preference for Na+ in this channel. Phylogenetic analysis assigns the Nematostella Na+-selective channel to a channel group unique to Cnidaria, which diverged >540 million years ago from Ca2+-conducting Na+ channel homologs. The identification of Cnidarian Na+-selective ion channels distinct from the channels of bilaterian animals indicates that selectivity for Na+ in neuronal signaling emerged independently in these two animal lineages.This study was supported by
a research grant from the Austrian National Science Foundation (FWF P
21108-B17) to U.T., and by a United States-Israel Binational Agricultural Research and Development Grant (IS-4313-10) and an Israeli Science Foundation
grant (107/08) to M.G
The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN
SDSS J015957.64+003310.5 is an X-ray selected, AGN from the Stripe
82X survey that transitioned from a Type 1 quasar to a Type 1.9 AGN between
2000 and 2010. This is the most distant AGN, and first quasar, yet observed to
have undergone such a dramatic change. We re-observed the source with the
double spectrograph on the Palomar 5m telescope in July 2014 and found that the
spectrum is unchanged since 2010. From fitting the optical spectra, we find
that the AGN flux dropped by a factor of 6 between 2000 and 2010 while the
broad H emission faded and broadened. Serendipitous X-ray observations
caught the source in both the bright and dim state, showing a similar 2-10 keV
flux diminution as the optical while lacking signatures of obscuration. The
optical and X-ray changes coincide with -band magnitude variations over
multiple epochs of Stripe 82 observations. We demonstrate that variable
absorption, as might be expected from the simplest AGN unification paradigm,
does not explain the observed photometric or spectral properties. We interpret
the changing state of J0159+0033 to be caused by dimming of the AGN continuum,
reducing the supply of ionizing photons available to excite gas in the
immediate vicinity around the black hole. J0159+0033 provides insight into the
intermittency of black hole growth in quasars, as well as an unprecedented
opportunity to study quasar physics (in the bright state) and the host galaxy
(in the dim state), which has been impossible to do in a single sources until
now.Comment: accepted for publication in Ap
The High-Density Ionized Gas in the Central Parsecs of the Galaxy
We report the results from observations of H30 line emission in Sgr A
West with the Submillimeter Array at a resolution of 2\arcsec and a field of
view of about 40\arcsec. The H30 line is sensitive to the high-density
ionized gas in the minispiral structure. We compare the velocity field obtained
from H30 line emission to a Keplerian model, and our results suggest
that the supermassive black hole at Sgr A* dominates the dynamics of the
ionized gas. However, we also detect significant deviations from the Keplerian
motion, which show that the impact of strong stellar winds from the massive
stars along the ionized flows and the interaction between Northern and Eastern
arms play significant roles in the local gas dynamics.Comment: 4 pages, 2 figure
Are there gender differences in the geography of alcohol-related mortality in Scotland? An ecological study
<b>Background</b>
There is growing concern about alcohol-related harm, particularly within Scotland which has some of the highest rates of alcohol-related death in western Europe. There are large gender differences in alcohol-related mortality rates in Scotland and in other countries, but the reasons for these differences are not clearly understood. In this paper, we aimed to address calls in the literature for further research on gender differences in the causes, contexts and consequences of alcohol-related harm. Our primary research question was whether the kind of social environment which tends to produce higher or lower rates of alcohol-related mortality is the same for both men and women across Scotland.
<b>Methods</b>
Cross-sectional, ecological design. A comparison was made between spatial variation in men's and women's age-standardised alcohol-related mortality rates in Scotland using maps, Moran's Index, linear regression and spatial analyses of residuals. Directly standardised mortality rates were derived from individual level records of death registration, 2000–2005 (n = 8685).
<b>Results</b>
As expected, men's alcohol-related mortality rate substantially exceeded women's and there was substantial spatial variation in these rates for both men and women within Scotland. However, there was little spatial variation in the relationship between men's and women's alcohol-mortality rates (r2 = 0.73); areas with relatively high rates of alcohol-related mortality for men tended also to have relatively high rates for women. In a small number of areas (8 out of 144) the relationship between men's and women's alcohol-related mortality rates was significantly different.
<b>Conclusion</b>
In as far as geographic location captures exposure to social and economic environment, our results suggest that the relationship between social and economic environment and alcohol-related harm is very similar for men and women. The existence of a small number of areas in which men's and women's alcohol-related mortality had an different relationship suggests that some places may have unusual drinking cultures. These might prove useful for further investigations into the factors which influence drinking behaviour in men and women
LoCuSS: Luminous infrared galaxies in the merging cluster Abell 1758 at z=0.28
We present the first galaxy evolution results from the Local Cluster
Substructure Survey (LoCuSS), a multi-wavelength survey of 100 X-ray selected
galaxy clusters at 0.15<z<0.30. LoCuSS combines far-UV through far-IR
observations of cluster galaxies with gravitational lensing analysis and X-ray
data to investigate the interplay between the hierarchical assembly of clusters
and the evolution of cluster galaxies. Here we present new panoramic
Spitzer/MIPS 24micron observations of the merging cluster Abell 1758 at z=0.279
spanning 6.5x6.5Mpc and reaching a 90% completeness limit of 400uJy. We
estimate a global cluster SFR of 910\pm320 M_sun/yr within 3 Mpc of the cluster
centre, originating from 42 galaxies with L_IR > 5x10^10 L_sun. The obscured
activity in A1758 is therefore comparable with that in Cl 0024+1654, the most
active cluster previously studied at 24um. The obscured galaxies faithfully
trace the cluster potential as revealed by the weak-lensing mass map of the
cluster, including numerous mass peaks at R~2-3Mpc that are likely associated
with infalling galaxy groups and filamentary structures. However the core
(R<500kpc) of A1758N is 2x more active in the IR than that of A1758S, likely
reflecting differences in the recent dynamical history of the two clusters. The
24micron results from A1758 therefore suggest that dust-obscured cluster
galaxies are common in merging clusters and suggests that obscured activity in
clusters is triggered by both the details of cluster-cluster mergers and
processes that operate at larger radii including those within in-falling
groups. Our ongoing far-UV through far-IR observations of a large sample of
clusters should allow us to disentangle the different physical processes
responsible for triggering obscured star formation in clusters.Comment: 13 pages, 9 figures. Accepted for publication in MNRA
A chemical transport model study of plume-rise and particle size distribution for the Athabasca oil sands
We evaluate four high-resolution model simulations of pollutant
emissions, chemical transformation, and downwind transport for the Athabasca
oil sands using the Global Environmental Multiscale – Modelling Air-quality
and Chemistry (GEM-MACH) model, and compare model results with surface
monitoring network and aircraft observations of multiple pollutants, for
simulations spanning a time period corresponding to an aircraft measurement
campaign in the summer of 2013. We have focussed here on the impact of
different representations of the model's aerosol size distribution and
plume-rise parameterization on model results.
The use of a more finely resolved representation of the aerosol size
distribution was found to have a significant impact on model performance,
reducing the magnitude of the original surface PM2.5 negative biases
32 %, from −2.62 to −1.72 µg m−3.
We compared model predictions of SO2, NO2, and speciated
particulate matter concentrations from simulations employing the commonly
used Briggs (1984) plume-rise algorithms to redistribute emissions from large
stacks, with stack plume observations. As in our companion paper (Gordon et
al., 2017), we found that Briggs algorithms
based on estimates of atmospheric stability at the stack height resulted in
under-predictions of plume rise, with 116 out of 176 test cases falling below
the model : observation 1 : 2 line, 59 cases falling within a factor of 2
of the observed plume heights, and an average model plume height of 289 m
compared to an average observed plume height of 822 m. We used a
high-resolution meteorological model to confirm the presence of significant
horizontal heterogeneity in the local meteorological conditions driving plume
rise. Using these simulated meteorological conditions at the stack locations,
we found that a layered buoyancy approach for estimating plume rise in stable
to neutral atmospheres, coupled with the assumption of free rise in
convectively unstable atmospheres, resulted in much better model performance
relative to observations (124 out of 176 cases falling within a factor of 2
of the observed plume height, with 69 of these cases above and 55 of these
cases below the 1 : 1 line and within a factor of 2 of observed values).
This is in contrast to our companion paper, wherein this layered approach
(driven by meteorological observations not co-located with the stacks) showed
a relatively modest impact on predicted plume heights. Persistent issues with
over-fumigation of plumes in the model were linked to a more rapid decrease
in simulated temperature with increasing height than was observed. This in
turn may have led to overestimates of near-surface diffusivity, resulting in
excessive fumigation
Radiation damage in the LHCb vertex locator
The LHCb Vertex Locator (VELO) is a silicon strip detector designed to reconstruct charged particle trajectories and vertices produced at the LHCb interaction region. During the first two years of data collection, the 84 VELO sensors have been exposed to a range of fluences up to a maximum value of approximately 45 × 1012 1 MeV neutron equivalent (1 MeV neq). At the operational sensor temperature of approximately −7 °C, the average rate of sensor current increase is 18 μA per fb−1, in excellent agreement with predictions. The silicon effective bandgap has been determined using current versus temperature scan data after irradiation, with an average value of Eg = 1.16±0.03±0.04 eV obtained. The first observation of n+-on-n sensor type inversion at the LHC has been made, occurring at a fluence of around 15 × 1012 of 1 MeV neq. The only n+-on-p sensors in use at the LHC have also been studied. With an initial fluence of approximately 3 × 1012 1 MeV neq, a decrease in the Effective Depletion Voltage (EDV) of around 25 V is observed. Following this initial decrease, the EDV increases at a comparable rate to the type inverted n+-on-n type sensors, with rates of (1.43±0.16) × 10−12 V/ 1 MeV neq and (1.35±0.25) × 10−12 V/ 1 MeV neq measured for n+-on-p and n+-on-n type sensors, respectively. A reduction in the charge collection efficiency due to an unexpected effect involving the second metal layer readout lines is observed
Cost-effectiveness of Implementing Low-Tidal Volume Ventilation in Patients With Acute Lung Injury
Background: Despite widespread guidelines recommending the use of lung-protective ventilation (LPV) in patients with acute lung injury (ALI), many patients do not receive this lifesaving therapy. We sought to estimate the incremental clinical and economic outcomes associated with LPV and determined the maximum cost of a hypothetical intervention to improve adherence with LPV that remained cost-effective.
Methods: Adopting a societal perspective, we developed a theoretical decision model to determine the cost-effectiveness of LPV compared to non-LPV care. Model inputs were derived from the literature and a large population-based cohort of patients with ALI. Cost-effectiveness was determined as the cost per life saved and the cost per quality-adjusted life-years (QALYs) gained.
Results: Application of LPV resulted in an increase in QALYs gained by 15% (4.21 years for non-LPV vs 4.83 years for LPV), and an increase in lifetime costs of 99,588 for non-LPV vs 22,566 per life saved at hospital discharge and 9,482. Results were robust to a wide range of economic and patient parameter assumptions.
Conclusions: Even a costly intervention to improve adherence with low-tidal volume ventilation in patients with ALI reduces death and is cost-effective by current societal standards.NIH F32HL090220.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/84154/1/Cooke - CEA LPV.pd
Performance of the LHCb vertex locator
The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment. The performance of the detector during the first years of its physics operation is reviewed. The system is operated in vacuum, uses a bi-phase CO2 cooling system, and the sensors are moved to 7 mm from the LHC beam for physics data taking. The performance and stability of these characteristic features of the detector are described, and details of the material budget are given. The calibration of the timing and the data processing algorithms that are implemented in FPGAs are described. The system performance is fully characterised. The sensors have a signal to noise ratio of approximately 20 and a best hit resolution of 4 μm is achieved at the optimal track angle. The typical detector occupancy for minimum bias events in standard operating conditions in 2011 is around 0.5%, and the detector has less than 1% of faulty strips. The proximity of the detector to the beam means that the inner regions of the n+-on-n sensors have undergone space-charge sign inversion due to radiation damage. The VELO performance parameters that drive the experiment's physics sensitivity are also given. The track finding efficiency of the VELO is typically above 98% and the modules have been aligned to a precision of 1 μm for translations in the plane transverse to the beam. A primary vertex resolution of 13 μm in the transverse plane and 71 μm along the beam axis is achieved for vertices with 25 tracks. An impact parameter resolution of less than 35 μm is achieved for particles with transverse momentum greater than 1 GeV/c
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