577 research outputs found
First Results of the Phase II SIMPLE Dark Matter Search
We report results of a 14.1 kgd measurement with 15 superheated droplet
detectors of total active mass 0.208 kg, comprising the first stage of a 30 kgd
Phase II experiment. In combination with the results of the neutron-spin
sensitive XENON10 experiment, these results yield a limit of |a_p| < 0.32 for
M_W = 50 GeV/c2 on the spin-dependent sector of weakly interacting massive
particle-nucleus interactions with a 50% reduction in the previously allowed
region of the phase space formerly defined by XENON, KIMS and PICASSO. In the
spin-independent sector, a limit of 2.3x10-5 pb at M_W = 45 GeV/c2 is obtained.Comment: 4 pages, 4 figures; PRL-accepted version with corrected SI contour
(Fig. 4
Final Analysis and Results of the Phase II SIMPLE Dark Matter Search
We report the final results of the Phase II SIMPLE measurements, comprising
two run stages of 15 superheated droplet detectors each, the second stage
including an improved neutron shielding. The analyses includes a refined signal
analysis, and revised nucleation efficiency based on reanalysis of
previously-reported monochromatic neutron irradiations. The combined results
yield a contour minimum of \sigma_{p} = 4.2 x 10^-3 pb at 35 GeV/c^2 on the
spin-dependent sector of WIMP-proton interactions, the most restrictive to date
from a direct search experiment and overlapping for the first time results
previously obtained only indirectly. In the spin-independent sector, a minimum
of 3.6 x 10^-6 pb at 35 GeV/c^2 is achieved, with the exclusion contour
challenging the recent CoGeNT region of current interest.Comment: revised, PRL-accepted version with slightly weakened limit contour
The SIMPLE Phase II Dark Matter Search
Phase II of SIMPLE (Superheated Instrument for Massive ParticLe Experiments)
searched for astroparticle dark matter using superheated liquid
CClF droplet detectors. Each droplet generally requires an energy
deposition with linear energy transfer (LET) 150 keV/m for a
liquid-to-gas phase transition, providing an intrinsic rejection against
minimum ionizing particles of order 10, and reducing the backgrounds to
primarily and neutron-induced recoil events. The droplet phase
transition generates a millimetric-sized gas bubble which is recorded by
acoustic means. We describe the SIMPLE detectors, their acoustic
instrumentation, and the characterizations, signal analysis and data selection
which yield a particle-induced, "true nucleation" event detection efficiency of
better than 97% at a 95% C.L. The recoil- event discrimination,
determined using detectors first irradiated with neutrons and then doped with
alpha emitters, provides a recoil identification of better than 99%; it differs
from those of COUPP and PICASSO primarily as a result of their different
liquids with lower critical LETs. The science measurements, comprising two
shielded arrays of fifteen detectors each and a total exposure of 27.77 kgd,
are detailed. Removal of the 1.94 kgd Stage 1 installation period data, which
had previously been mistakenly included in the data, reduces the science
exposure from 20.18 to 18.24 kgd and provides new contour minima of
= 4.3 10 pb at 35 GeV/c in the
spin-dependent sector of WIMP-proton interactions and = 3.6
10 pb at 35 GeV/c in the spin-independent sector. These
results are examined with respect to the fluorine spin and halo parameters used
in the previous data analysis.Comment: 20 pages, 19 figures; accepted Physical Review
Prognostic value of the ratio between prothesis area and indexed annulus area measured by multiSlice-CT for transcatheter aortic valve implantation procedures
Background Postprocedural aortic regurgitations following transcatheter aortic valve implantation (TAVI) procedures remain an is- sue. Benefit of oversizing strategies to prevent them isn’t well established. We compared different level of oversizing in our cohort of con- secutive patients to address if severe oversizing compared to normal sizing had an impact on post-procedural outcomes. Methods From January 2010 to August 2013, consecutive patients were referred for TAVI with preoperative Multislice-CT (MSCT) and the procedures were achieved using Edwards Sapien® or Corevalve devices®. Retrospectively, according to pre-procedural MSCT and the valve size, pa- tients were classified into three groups: normal, moderate and severe oversizing; depending on the ratio between the prosthesis area and the annulus area indexed and measured on MSCT. Main endpoint was mid-term mortality and secondary endpoints were the Valve Academic Research Consortium (VARC-2) endpoints. Results Two hundred and sixty eight patients had a MSCT and underwent TAVI procedure, with mainly Corevalve®. While all-cause and cardiovascular mortality rates were similar in all groups, post-procedural new pacemaker (PM) implantation rate was significantly higher in the severe oversizing group (P = 0.03), while we observed more in-hospital congestive heart-failure (P = 0.02) in the normal sizing group. There was a trend toward more moderate to severe aortic regurgitation (AR) in the normal sizing group (P = 0.07). Conclusions Despite a higher rate of PM implantation, oversizing based on this ratio reduces aortic leak with lower rates of post-procedural complications and a similar mid-term survival
Undocumented Migrants in Switzerland: Geographical Origin Versus Legal Status as Risk Factor for Tuberculosis
Undocumented migrants, meaning migrants without a legal residency permit, come to Geneva from countries with high tuberculosis (TB) incidence. We estimate here whether being undocumented is a determinant of TB, independently of origin. Cross-sectional study including undocumented migrants in a TB screening program in 2002; results were compared to 12,904 age and frequency matched participants in a general TB screening program conducted at various workplaces in Geneva, Switzerland from 1992 to 2002. A total of 206 undocumented migrants (36% male, 64% female, mean age 37.8 years (SD 11.8), 82.5% from Latin America) participated in the TB screening program. Compared to legal residents, undocumented migrants had an adjusted OR for TB-related fibrotic signs of 1.7 (95% CI 0.8;3.7). The OR of TB-related fibrotic signs for Latin American (vs. other) origin was 2.7 (95% CI 1.6;4.7) among legal residents and 5.5 (95% CI 2.8;10.8) among undocumented migrants. Chest X-ray screening identified a higher proportion of TB-related fibrotic signs among Latin Americans, independently of their residency statu
Segmenting white matter hyperintensities on isotropic three-dimensional Fluid Attenuated Inversion Recovery magnetic resonance images: Assessing deep learning tools on a Norwegian imaging database
An important step in the analysis of magnetic resonance imaging (MRI) data for neuroimaging is the automated segmentation of white matter hyperintensities (WMHs). Fluid Attenuated Inversion Recovery (FLAIR-weighted) is an MRI contrast that is particularly useful to visualize and quantify WMHs, a hallmark of cerebral small vessel disease and Alzheimer's disease (AD). In order to achieve high spatial resolution in each of the three voxel dimensions, clinical MRI protocols are evolving to a three-dimensional (3D) FLAIR-weighted acquisition. The current study details the deployment of deep learning tools to enable automated WMH segmentation and characterization from 3D FLAIR-weighted images acquired as part of a national AD imaging initiative. Based on data from the ongoing Norwegian Disease Dementia Initiation (DDI) multicenter study, two 3D models-one off-the-shelf from the NVIDIA nnU-Net framework and the other internally developed-were trained, validated, and tested. A third cutting-edge Deep Bayesian network model (HyperMapp3r) was implemented without any de-novo tuning to serve as a comparison architecture. The 2.5D in-house developed and 3D nnU-Net models were trained and validated in-house across five national collection sites among 441 participants from the DDI study, of whom 194 were men and whose average age was (64.91 +/- 9.32) years. Both an external dataset with 29 cases from a global collaborator and a held-out subset of the internal data from the 441 participants were used to test all three models. These test sets were evaluated independently. The ground truth human-in-the-loop segmentation was compared against five established WMH performance metrics. The 3D nnU-Net had the highest performance out of the three tested networks, outperforming both the internally developed 2.5D model and the SOTA Deep Bayesian network with an average dice similarity coefficient score of 0.76 +/- 0.16. Our findings demonstrate that WMH segmentation models can achieve high performance when trained exclusively on FLAIR input volumes that are 3D volumetric acquisitions. Single image input models are desirable for ease of deployment, as reflected in the current embedded clinical research project. The 3D nnU-Net had the highest performance, which suggests a way forward for our need to automate WMH segmentation while also evaluating performance metrics during on-going data collection and model retraining
Prophylaxis failure is associated with a specific Pneumocystis carinii genotype.
To investigate the possible association between Pneumocystis carinii types and various clinical and demographic parameters, we used molecular typing to analyze 93 bronchoalveolar lavage specimens from patients with P. carinii pneumonia (PCP). Multivariate regression analysis revealed an association between being infected with a specific P. carinii genotype and receiving anti-PCP prophylaxis (odds ratio, 4.4; 95% confidence interval, 1.0-18.6; P=.05), although no association with a specific drug was detected
Nitrogen transfers off Walvis Bay: a 3-D coupled physical/biogeochemical modeling approach in the Namibian upwelling system
Eastern boundary upwelling systems (EBUS) are regions of high primary production often associated with oxygen minimum zones (OMZs). They represent key regions for the oceanic nitrogen (N) cycle. By exporting organic matter (OM) and nutrients produced in the coastal region to the open ocean, EBUS can play an important role in sustaining primary production in subtropical gyres. However, losses of fixed inorganic N through denitrification and anammox processes take place in oxygen depleted environments such as EBUS, and can potentially mitigate the role of these regions as a source of N to the open ocean. EBUS can also represent a considerable source of nitrous oxide (N2O) to the atmosphere, affecting the atmospheric budget of N2O.
In this paper a 3-D coupled physical/biogeochemical model (ROMS/BioEBUS) is used to investigate the N budget in the Namibian upwelling system. The main processes linked to EBUS and associated OMZs are taken into account. The study focuses on the northern part of the Benguela upwelling system (BUS), especially the Walvis Bay area (between 22° S and 24° S) where the OMZ is well developed. Fluxes of N off the Walvis Bay area are estimated in order to understand and quantify (1) the total N offshore export from the upwelling area, representing a possible N source that sustains primary production in the South Atlantic subtropical gyre; (2) export production and subsequent losses of fixed N via denitrification and anammox under suboxic conditions (O2 < 25 mmol O2 m−3); and (3) the N2O emission to the atmosphere in the upwelling area.
In the mixed layer, the total N offshore export is estimated as 8.5 ± 3.9 × 1010 mol N yr−1 at 10° E off the Walvis Bay area, with a mesoscale contribution of 20%. Extrapolated to the whole BUS, the coastal N source for the subtropical gyre corresponds to 0.1 ± 0.04 mol N m−2 yr−1. This N flux represents a major source of N for the gyre compared with other N sources, and contributes 28% of the new primary production estimated for the South Atlantic subtropical gyre.
Export production (16.9 ± 1.3 × 1010 mol N yr−1) helps to maintain an OMZ off Namibia in which coupled nitrification, denitrification and anammox processes lead to losses of fixed N and N2O production. However, neither N losses (0.04 ± 0.025 × 1010 mol N yr−1) nor N2O emissions (0.03 ± 0.002 × 1010 mol N yr−1) significantly impact the main N exports of the Walvis Bay area.
The studied area does not significantly contribute to N2O emissions (0.5 to 2.7%) compared to the global coastal upwelling emissions. Locally produced N2O is mostly advected southward by the poleward undercurrent
Assessment of Microvascular Disease in Heart and Brain by MRI: Application in Heart Failure with Preserved Ejection Fraction and Cerebral Small Vessel Disease
The objective of this review is to investigate the commonalities of microvascular (small vessel) disease in heart failure with preserved ejection fraction (HFpEF) and cerebral small vessel disease (CSVD). Furthermore, the review aims to evaluate the current magnetic resonance imaging (MRI) diagnostic techniques for both conditions. By comparing the two conditions, this review seeks to identify potential opportunities to improve the understanding of both HFpEF and CSVD
Hyperlactatemia and Antiretroviral Therapy: The Swiss HIV Cohort Study
The prevalence, clinical presentation, and risk factors for hyperlactatemia among patients receiving antiretroviral therapy was determined during a 1-month period for patients in the Swiss HIV Cohort Study. Overall, 73 (8.3%) of 880 patients presented an increase in serum lactate of >1.1 times the upper normal limit (UNL). For 9 patients (1%), lactate elevation was moderate or severe (>2.2 times the UNL). Patients who presented with hyperlactatemia were more likely to be receiving stavudine with or without didanosine (odds ratio, 2.7; 95% confidence interval, 1.5-4.8), as compared with patients who received zidovudine-based regimens. The risk increased with increasing time receiving stavudine with or without didanosine. The association between hyperlactatemia and stavudine with or without didanosine was not biased by these medications being more recently available and, therefore, being given preferentially to patients who had prolonged use of nucleoside analog reverse-transcriptase inhibitors. Hyperlactatemia was associated with lipoatrophy, hyperlipidemia, and hyperglycemia. Age, sex, or stage of infection with human immunodeficiency virus were not predictive of hyperlactatemia. Determination of lactate levels may prove useful in the screening for mitochondrial toxicit
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