1,809 research outputs found
Eosinophilic aseptic arachnoiditis: A neurological complication in HIV-negative drug-addicts
Abstract.: The finding of an eosinophilic aseptic meningitis in IV drug abuse is usually suggestive of an opportunistic infection or an allergic reaction. However, HIV-negative patients are at lower risk for developing these complications. Two young HIV-negative patients, with previous intravenous polytoxicomany, developed cystic arachnoiditis over the spinal cord associated with eosinophilic meningitis. Histology of the meningeal spinal cord lesions revealed a vasculocentric mixed inflammatory reaction. In one patient prednisone led to marked clinical improvement. Since infection, vasculitis, sarcoidosis and previous myelography were ruled out, we believe that the syndrome of eosinophilic aseptic arachnoiditis may be related to an hyperergic reaction in the meniges toward drug-adulterants inoculated through the intravenous rout
An experimental study of columnar crystals using monodisperse microbubbles
We investigate the ordered arrangements of monodisperse microbub bles con ned within narrow cylinders. These foams were imaged using X ray tomography, allowing the 3D positions of the bubbles of the foam to be accurately determined. The structure of these foams closely re semble the minimum energy con guration of hard spheres in cylindrical con nement as found in simulations. For larger ratios, , of cylinder to bubble diameter two and three layered crystals were formed. Each layer of these structures is found to be ordered, with each internal layer resem bling structures found at lower values. The average number of contacts per bubble is seen to increase wit
The role of posterior fossa decompression in acute cerebellitis
Background: We present two cases of children who were diagnosed with cerebellitis with acute cerebellar swelling. This rare pathology is potentially fatal, and no clear treatment guidelines are described in the literature. Discussion: Considering our experience, we discuss the different therapeutic strategies and propose aggressive surgical measures consisting of external ventricular drainage and posterior fossa decompression in case of failure of early response to medical treatment to limit secondary cerebellar and brainstem lesion
Eosinophilic aseptic arachnoiditis. A neurological complication in HIV-negative drug-addicts.
The finding of an eosinophilic aseptic meningitis in IV drug abuse is usually suggestive of an opportunistic infection or an allergic reaction. However, HIV-negative patients are at lower risk for developing these complications. Two young HIV-negative patients, with previous intravenous polytoxicomany, developed cystic arachnoiditis over the spinal cord associated with eosinophilic meningitis. Histology of the meningeal spinal cord lesions revealed a vasculocentric mixed inflammatory reaction. In one patient prednisone led to marked clinical improvement. Since infection, vasculitis, sarcoidosis and previous myelography were ruled out, we believe that the syndrome of eosinophilic aseptic arachnoiditis may be related to an hyperergic reaction in the meniges toward drug-adulterants inoculated through the intravenous route
Cluster analysis of the organic peaks in bulk mass spectra obtained during the 2002 New England Air Quality Study with an Aerodyne aerosol mass spectrometer
International audienceWe applied hierarchical cluster analysis to an Aerodyne aerosol mass spectrometer (AMS) bulk mass spectral dataset collected aboard the NOAA research vessel Ronald H. Brown during the 2002 New England Air Quality Study off the east coast of the United States. Emphasizing the organic peaks, the cluster analysis yielded a series of categories that are distinguishable with respect to their mass spectra and their occurrence as a function of time. The differences between the categories mainly arise from relative intensity changes rather than from the presence or absence of specific peaks. The most frequent category exhibits a strong signal at m/z 44 and represents oxidized organic matter most probably originating from both, anthropogenic as well as biogenic sources. On the basis of spectral and trace gas correlations, the second most common category with strong signals at m/z 29, 43, and 44 contains contributions from isoprene oxidation products. The third through the fifth most common categories have peak patterns characteristic of monoterpene oxidation products and were most frequently observed when air masses from monoterpene rich regions were sampled. Taken together, the second through the fifth most common categories represent as much as 5 ”g/m3 organic aerosol mass ? 17% of the total organic mass ? that can be attributed to biogenic sources. These numbers have to be viewed as lower limits since the most common category was attributed to anthropogenic sources for this calculation. The cluster analysis was also very effective in identifying a few contaminated mass spectra that were not removed during pre-processing. This study demonstrates that hierarchical clustering is a useful tool to analyze the complex patterns of the organic peaks in bulk aerosol mass spectra from a field study
The role of posterior fossa decompression in acute cerebellitis.
BACKGROUND: We present two cases of children who were diagnosed with cerebellitis with acute cerebellar swelling. This rare pathology is potentially fatal, and no clear treatment guidelines are described in the literature. DISCUSSION: Considering our experience, we discuss the different therapeutic strategies and propose aggressive surgical measures consisting of external ventricular drainage and posterior fossa decompression in case of failure of early response to medical treatment to limit secondary cerebellar and brainstem lesions
Taxing the Informal Economy: The Current State of Knowledge and Agendas for Future Research
This paper reviews the literature on taxation of the informal economy, taking stock of key debates
and drawing attention to recent innovations. Conventionally, the debate on whether to tax has frequently focused
on the limited revenue potential, high cost of collection, and potentially adverse impact on small firms. Recent
arguments have increasingly emphasised the more indirect benefits of informal taxation in relation to economic
growth, broader tax compliance, and governance. More research is needed, we argue, into the relevant costs and
benefits for all, including quasi-voluntary compliance, political and administrative incentives for reform, and
citizen-state bargaining over taxation
Performance and durability of broadband antireflection coatings for thin film CdTe solar cells
Light reflection from the glass surface of a photovoltaic (PV) module is a significant source of energy
loss for all types of PV devices. The reflection at the glass and air interface accounts for 4% of the total
energy. Single layer antireflection coatings with sufficiently low refractive index have been used, such as
those using magnesium fluoride or porous silica, but these are only effective over a narrow range of
wavelengths. In this paper, the authors report on the design, deposition, and testing of multilayer
broadband antireflection coatings. These coatings reduce the weighted average reflection over the
wavelength range used by thin film CdTe devices to just 1.22%, resulting in a 3.6% relative increase in
device efficiency. The authors have used multilayer stacks consisting of silica and zirconia layers
deposited using reactive magnetron sputtering. Details of the stack design, sputter deposition process
parameters, and the optical and microstructural properties of the layers are provided. Antireflection
coatings on glass exposed to the outdoors must not degrade over the lifetime of the module. A
comprehensive set of accelerated environmental durability tests has been carried out in accordance with
IEC 61646 PV qualification tests. The durability tests confirmed no damage to the coatings or
performance drop as a result of thermal cycling or damp heat. All attempts to perform pull tests resulted
in either adhesive or substrate failure, with no damage to the coating itself. The coatings also passed acid
attack tests. Scratch resistance, abrasion resistance, and adhesion tests have also been conducted. The
optical performance of the coatings was monitored during these tests, and the coatings were visually
inspected for any sign of mechanical failure. These tests provide confidence that broadband
antireflection coatings are highly durable and will maintain their performance over the lifetime of the
solar module. All dielectric metal-oxide multilayer coatings have better optical performance and superior
durability compared with alternative single layer porous solâgel coatings. Thin film CdTe devices are
particularly problematic because the antireflection coating is applied to one side of the glass, while
device layers are deposited directly on to the opposite glass surface in the superstrate configuration. In
thin film CdTe production, the glass is exposed to high temperature processes during the absorber deposition
and the cadmium chloride activation treatment. If glass precoated with a broadband antireflection
coating is to be used, then the coating must withstand temperatures of up to 550 C. Surprisingly, our
studies have shown that multilayer silica/zirconia antireflection coatings on soda lime glass remain unaffected
by temperatures reaching 600 C, at which point mild crazing is observed. This is an important
observation, demonstrating that low cost glass, which is preprocessed with a broadband antireflection
coating, is directly useable in thin film CdTe module production
Investigating the TeV Morphology of MGRO J1908+06 with VERITAS
We report on deep observations of the extended TeV gamma-ray source MGRO
J1908+06 made with the VERITAS very high energy (VHE) gamma-ray observatory.
Previously, the TeV emission has been attributed to the pulsar wind nebula
(PWN) of the Fermi-LAT pulsar PSR J1907+0602. We detect MGRO J1908+06 at a
significance level of 14 standard deviations (14 sigma) and measure a photon
index of 2.20 +/- 0.10_stat +/- 0.20_sys. The TeV emission is extended,
covering the region near PSR J1907+0602 and also extending towards SNR
G40.5--0.5. When fitted with a 2-dimensional Gaussian, the intrinsic extension
has a standard deviation of sigma_src = 0.44 +/- 0.02 degrees. In contrast to
other TeV PWNe of similar age in which the TeV spectrum softens with distance
from the pulsar, the TeV spectrum measured near the pulsar location is
consistent with that measured at a position near the rim of G40.5--0.5, 0.33
degrees away.Comment: To appear in ApJ, 8 page
Deep Broadband Observations of the Distant Gamma-ray Blazar PKS 1424+240
We present deep VERITAS observations of the blazar PKS 1424+240, along with
contemporaneous Fermi Large Area Telescope, Swift X-ray Telescope and Swift UV
Optical Telescope data between 2009 February 19 and 2013 June 8. This blazar
resides at a redshift of , displaying a significantly attenuated
gamma-ray flux above 100 GeV due to photon absorption via pair-production with
the extragalactic background light. We present more than 100 hours of VERITAS
observations from three years, a multiwavelength light curve and the
contemporaneous spectral energy distributions. The source shows a higher flux
of (2.1) ph ms above 120 GeV in 2009 and
2011 as compared to the flux measured in 2013, corresponding to
(1.02) ph ms above 120 GeV. The measured
differential very high energy (VHE; GeV) spectral indices are
3.80.3, 4.30.6 and 4.50.2 in 2009, 2011 and 2013,
respectively. No significant spectral change across the observation epochs is
detected. We find no evidence for variability at gamma-ray opacities of greater
than , where it is postulated that any variability would be small and
occur on longer than year timescales if hadronic cosmic-ray interactions with
extragalactic photon fields provide a secondary VHE photon flux. The data
cannot rule out such variability due to low statistics.Comment: ApJL accepted March 17, 201
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