981 research outputs found
Digital Beamforming and Traffic Monitoring Using the new FSAR System of DLR
In November 2006 the first X-band test flight of DLR’s new FSAR system has been performed successfully and in February 2007 the first flight campaign has been conducted for acquiring experimental multi-channel data of controlled ground moving targets. In the paper the performed experiments and the used setup of the FSAR X-band section are described and preliminary results in the field of ground moving target indication and digital beamforming are presented
Nocturnal nitrogen oxides at a rural mountain-site in south-western Germany
A new, two-channel instrument for simultaneous NO3 and N2O5 monitoring was used to make the first comprehensive set of nocturnal NOx measurements (NO, NO2, NO3 and N2O5) at the Taunus Observatory, a rural mountain site (Kleiner Feldberg) in South-western Germany. In May 2008, NO3 and N2O5 mixing ratios were well above the instrumental detection limit (a few ppt) on all nights of the campaign and were characterised by large variability. The concentrations of NO3, N2O5 and NO2 were consistent with the equilibrium constant, K2, defining the rates of formation and thermal dissociation of N2O5. A steady-state lifetime analysis is consistent with the loss of nocturnal NOx being dominated by the reaction of NO3 with volatile organic compounds in this forested region, with N2O5 uptake to aerosols of secondary importance. Analysis of a limited dataset obtained at high relative humidity indicated that the loss of N2O5 by reaction with water vapour is less efficient (>factor 3) than derived using laboratory kinetic data. The fraction of NOx present as NO3 and N2O5 reached ~20% on some nights, with night-time losses of NOx competing with daytime losses
gcodeml: A Grid-enabled Tool for Detecting Positive Selection in Biological Evolution
One of the important questions in biological evolution is to know if certain
changes along protein coding genes have contributed to the adaptation of
species. This problem is known to be biologically complex and computationally
very expensive. It, therefore, requires efficient Grid or cluster solutions to
overcome the computational challenge. We have developed a Grid-enabled tool
(gcodeml) that relies on the PAML (codeml) package to help analyse large
phylogenetic datasets on both Grids and computational clusters. Although we
report on results for gcodeml, our approach is applicable and customisable to
related problems in biology or other scientific domains.Comment: 10 pages, 4 figures. To appear in the HealthGrid 2012 con
Elliptic flow and incomplete equilibration at RHIC
We argue that RHIC data, in particular those on the anisotropic flow
coefficients v_2 and v_4, suggest that the matter produced in the early stages
of nucleus-nucleus collisions is incompletely thermalized. We interpret the
parameter (1/S)(dN/dy), where S is the transverse area of the collision zone
and dN/dy the multiplicity density, as an indicator of the number of collisions
per particle at the time when elliptic flow is established, and hence as a
measure of the degree of equilibration. This number serves as a control
parameter which can be varied experimentally by changing the system size, the
centrality of the collision, or the beam energy. We provide predictions for
Cu-Cu collisions at RHIC as well as for Pb-Pb collisions at the LHC.Comment: 5 pages, 2 figures, minor correction
Zebrafish eda and edar Mutants Reveal Conserved and Ancestral Roles of Ectodysplasin Signaling in Vertebrates
The genetic basis of the development and variation of adult form of vertebrates is not well understood. To address this problem, we performed a mutant screen to identify genes essential for the formation of adult skeletal structures of the zebrafish. Here, we describe the phenotypic and molecular characterization of a set of mutants showing loss of adult structures of the dermal skeleton, such as the rays of the fins and the scales, as well as the pharyngeal teeth. The mutations represent adult-viable, loss of function alleles in the ectodysplasin (eda) and ectodysplasin receptor (edar) genes. These genes are frequently mutated in the human hereditary disease hypohidrotic ectodermal dysplasia (HED; OMIM 224900, 305100) that affects the development of integumentary appendages such as hair and teeth. We find mutations in zebrafish edar that affect similar residues as mutated in human cases of HED and show similar phenotypic consequences. eda and edar are not required for early zebrafish development, but are rather specific for the development of adult skeletal and dental structures. We find that the defects of the fins and scales are due to the role of Eda signaling in organizing epidermal cells into discrete signaling centers of the scale epidermal placode and fin fold. Our genetic analysis demonstrates dose-sensitive and organ-specific response to alteration in levels of Eda signaling. In addition, we show substantial buffering of the effect of loss of edar function in different genetic backgrounds, suggesting canalization of this developmental system. We uncover a previously unknown role of Eda signaling in teleosts and show conservation of the developmental mechanisms involved in the formation and variation of both integumentary appendages and limbs. Lastly, our findings point to the utility of adult genetic screens in the zebrafish in identifying essential developmental processes involved in human disease and in morphological evolution
Optimization strategies for fast detection of positive selection on phylogenetic trees
Motivation: The detection of positive selection is widely used to study gene and genome evolution, but its application remains limited by the high computational cost of existing implementations. We present a series of computational optimizations for more efficient estimation of the likelihood function on large-scale phylogenetic problems. We illustrate our approach using the branch-site model of codon evolution. Results: We introduce novel optimization techniques that substantially outperform both CodeML from the PAML package and our previously optimized sequential version SlimCodeML. These techniques can also be applied to other likelihood-based phylogeny software. Our implementation scales well for large numbers of codons and/or species. It can therefore analyse substantially larger datasets than CodeML. We evaluated FastCodeML on different platforms and measured average sequential speedups of FastCodeML (single-threaded) versus CodeML of up to 5.8, average speedups of FastCodeML (multi-threaded) versus CodeML on a single node (shared memory) of up to 36.9 for 12 CPU cores, and average speedups of the distributed FastCodeML versus CodeML of up to 170.9 on eight nodes (96 CPU cores in total). Availability and implementation: ftp://ftp.vital-it.ch/tools/FastCodeML/. Contact: [email protected] or [email protected]
A Novel H+ Conductance in Eosinophils: Unique Characteristics and Absence in Chronic Granulomatous Disease
Efficient mechanisms of H+ ion extrusion are crucial for normal NADPH oxidase function. However, whether the NADPH oxidase—in analogy with mitochondrial cytochromes—has an inherent H+ channel activity remains uncertain: electrophysiological studies did not find altered H+ currents in cells from patients with chronic granulomatous disease (CGD), challenging earlier reports in intact cells. In this study, we describe the presence of two different types of H+ currents in human eosinophils. The “classical” H+ current had properties similar to previously described H+ conductances and was present in CGD cells. In contrast, the “novel” type of H+ current had not been described previously and displayed unique properties: (a) it was absent in cells from gp91- or p47-deficient CGD patients; (b) it was only observed under experimental conditions that allowed NADPH oxidase activation; (c) because of its low threshold of voltage activation, it allowed proton influx and cytosolic acidification; (d) it activated faster and deactivated with slower and distinct kinetics than the classical H+ currents; and (e) it was ∼20-fold more sensitive to Zn2+ and was blocked by the histidine-reactive agent, diethylpyrocarbonate (DEPC). In summary, our results demonstrate that the NADPH oxidase or a closely associated protein provides a novel type of H+ conductance during phagocyte activation. The unique properties of this conductance suggest that its physiological function is not restricted to H+ extrusion and repolarization, but might include depolarization, pH-dependent signal termination, and determination of the phagosomal pH set point
Temporal factors in violence related injuries—An 11year trend analysis of violence-related injuries from a Swiss Emergency Department
Summary: Background: Injury from interpersonal violence is a major social and medical problem in the industrialized world. Little is known about the trends in prevalence and injury pattern or about the demographic characteristics of the patients involved. Methods: In this retrospective analysis, we screened the database of the Emergency Department of a large university hospital for all patients who were admitted for injuries due to interpersonal violence over an 11year period. For all patients identified, we gathered data on age, country of origin, quality of injury, and hospitalization or outpatient management. A trend analysis was performed using Kendall's tau-b correlation coefficients for regression analysis. Results: The overall number of patients admitted to our Emergency Department remained stable over the study period. Non-Swiss nationals were overrepresented in comparison to the demographics of the region where the study was conducted. There was a trend toward a more severe pattern of injury, such as an increase in the number of severe head injuries. Conclusions: Although the overall number of patients remained stable over the study period, there was an alarming trend toward a more severe pattern of injury, expressed by an increase in severe head trauma
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