454 research outputs found
Thomas-Fermi approximation to static vortex states in superfluid trapped atomic gases
We revise the Thomas-Fermi approximation for describing vortex states in Bose
condensates of magnetically trapped atoms. Our approach is based on considering
the hbar -> 0 limit rather than the N -> infinity limit as Thomas-Fermi
approximation in close analogy with the Fermi systems. Even for relatively
small numbers of trapped particles we find good agreement between
Gross-Pitaevskii and Thomas-Fermi calculations for the different contributions
to the total energy of the atoms in the condensate. We also discuss the
application of our approach to the description of vortex states in superfluid
fermionic systems in the Ginzburg-Landau regime.Comment: 11 pages, 6 figures, revtex4, substantially revised versio
Semi-Classical Description of the Average Pairing Properties in Nuclei
We present a new semi-classical theory for describing pairing in finite Fermi
systems. It is based in taking the , i.e. Thomas-Fermi, limit of
the gap equation written in the basis of the mean field (weak coupling). In
addition to the position dependence of the Fermi momentum, the size dependence
of the matrix elements of the pairing force is also taken into account in this
theory. An example typical for the nuclear situation shows the improvement of
this new approach over the standard Local Density Approximation. We also show
that if in this approach some shell fluctuations are introduced in the level
density, the arch structure displayed by the quantal gaps along isotopic chains
is almost recovered. We also point out that in heavy drip line nuclei pairing
is strongly reduced
Access to diagnosis and treatment of Chagas disease/infection in endemic and non-endemic countries in the XXI century.
In this article, Médicos Sin Fronteras (MSF) Spain faces the challenge of selecting, piecing together, and conveying in the clearest possible way, the main lessons learnt over the course of the last seven years in the world of medical care for Chagas disease. More than two thousand children under the age of 14 have been treated; the majority of whom come from rural Latin American areas with difficult access. It is based on these lessons learnt, through mistakes and successes, that MSF advocates that medical care for patients with Chagas disease be a reality, in a manner which is inclusive (not exclusive), integrated (with medical, psychological, social, and educational components), and in which the patient is actively followed. This must be a multi-disease approach with permanent quality controls in place based on primary health care (PHC). Rapid diagnostic tests and new medications should be available, as well as therapeutic plans and patient management (including side effects) with standardised flows for medical care for patients within PHC in relation to secondary and tertiary level, inclusive of epidemiological surveillance systems
Whistler Waves Driven by Anisotropic Strahl Velocity Distributions: Cluster Observations
Observed properties of the strahl using high resolution 3D electron velocity distribution data obtained from the Cluster/PEACE experiment are used to investigate its linear stability. An automated method to isolate the strahl is used to allow its moments to be computed independent of the solar wind core+halo. Results show that the strahl can have a high temperature anisotropy (T(perpindicular)/T(parallell) approximately > 2). This anisotropy is shown to be an important free energy source for the excitation of high frequency whistler waves. The analysis suggests that the resultant whistler waves are strong enough to regulate the electron velocity distributions in the solar wind through pitch-angle scatterin
Deriving a Provisional Tolerable Intake for Intravenous Exposure to Silver Nanoparticles Released from Medical Devices
Silver nanoparticles (AgNP) are incorporated into medical devices for their anti-microbial characteristics. The potential exposure and toxicity of AgNPs is unknown due to varying physicochemical particle properties and lack of toxicological data. The aim of this safety assessment is to derive a provisional tolerable intake (pTI) value for AgNPs released from blood-contacting medical devices. A literature review of in vivo studies investigating critical health effects induced from intravenous (i. v.) exposure to AgNPs was evaluated by the Annapolis Accords principles and Toxicological Data Reliability Assessment Tool (ToxRTool). The point of departure (POD) was based on an i. v. 28-day repeated AgNP (20 nm) dose toxicity study reporting an increase in relative spleen weight in rats with a 5% lower confidence bound of the benchmark dose (BMDL05) of 0.14 mg/kg bw/day. The POD was extrapolated to humans by a modifying factor of 1,000 to account for intraspecies variability, interspecies differences and lack of long-term toxicity data. The pTI for long-term i. v. exposure to 20 nm AgNPs released from blood-contacting medical devices was 0.14 μg/kg bw/day. This pTI may not be appropriate for nanoparticles of other physicochemical properties or routes of administration. The methodology is appropriate for deriving pTIs for nanoparticles in general
Cooper pair sizes in 11Li and in superfluid nuclei: a puzzle?
We point out a strong influence of the pairing force on the size of the two
neutron Cooper pair in Li, and to a lesser extent also in He. It
seems that these are quite unique situations, since Cooper pair sizes of stable
superfluid nuclei are very little influenced by the intensity of pairing, as
recently reported. We explore the difference between Li and heavier
superfulid nuclei, and discuss reasons for the exceptional situation in
Li.Comment: 9 pages. To be published in J. of Phys. G special issue on Open
  Problems in Nuclear Structure (OPeNST
Simultaneous quantification of 12 different nucleotides and nucleosides released from renal epithelium and in human urine samples using ion-pair reversed-phase HPLC
Nucleotides and nucleosides are not only involved in cellular metabolism but also act extracellularly via P1 and P2 receptors, to elicit a wide variety of physiological and pathophysiological responses through paracrine and autocrine signalling pathways. For the first time, we have used an ion-pair reversed-phase high-performance liquid chromatography ultraviolet (UV)-coupled method to rapidly and simultaneously quantify 12 different nucleotides and nucleosides (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, adenosine, uridine triphosphate, uridine diphosphate, uridine monophosphate, uridine, guanosine triphosphate, guanosine diphosphate, guanosine monophosphate, guanosine): (1) released from a mouse renal cell line (M1 cortical collecting duct) and (2) in human biological samples (i.e., urine). To facilitate analysis of urine samples, a solid-phase extraction step was incorporated (overall recovery rate ? 98 %). All samples were analyzed following injection (100 ?l) into a Synergi Polar-RP 80 Å (250 × 4.6 mm) reversed-phase column with a particle size of 10 ?m, protected with a guard column. A gradient elution profile was run with a mobile phase (phosphate buffer plus ion-pairing agent tetrabutylammonium hydrogen sulfate; pH 6) in 2-30 % acetonitrile (v/v) for 35 min (including equilibration time) at 1 ml min(-1) flow rate. Eluted compounds were detected by UV absorbance at 254 nm and quantified using standard curves for nucleotide and nucleoside mixtures of known concentration. Following validation (specificity, linearity, limits of detection and quantitation, system precision, accuracy, and intermediate precision parameters), this protocol was successfully and reproducibly used to quantify picomolar to nanomolar concentrations of nucleosides and nucleotides in isotonic and hypotonic cell buffers that transiently bathed M1 cells, and urine samples from normal subjects and overactive bladder patients
Acceleration of Solar Wind Ions by Nearby Interplanetary Shocks: Comparison of Monte Carlo Simulations with Ulysses Observations
The most stringent test of theoretical models of the first-order Fermi
mechanism at collisionless astrophysical shocks is a comparison of the
theoretical predictions with observational data on particle populations. Such
comparisons have yielded good agreement between observations at the
quasi-parallel portion of the Earth's bow shock and three theoretical
approaches, including Monte Carlo kinetic simulations. This paper extends such
model testing to the realm of oblique interplanetary shocks: here observations
of proton and alpha particle distributions made by the SWICS ion mass
spectrometer on Ulysses at nearby interplanetary shocks are compared with test
particle Monte Carlo simulation predictions of accelerated populations. The
plasma parameters used in the simulation are obtained from measurements of
solar wind particles and the magnetic field upstream of individual shocks. Good
agreement between downstream spectral measurements and the simulation
predictions are obtained for two shocks by allowing the the ratio of the
mean-free scattering length to the ionic gyroradius, to vary in an optimization
of the fit to the data. Generally small values of this ratio are obtained,
corresponding to the case of strong scattering. The acceleration process
appears to be roughly independent of the mass or charge of the species.Comment: 26 pages, 6 figures, AASTeX format, to appear in the Astrophysical
  Journal, February 20, 199
Deep Learning Enables Fast and Accurate Imputation of Gene Expression
A question of fundamental biological significance is to what extent the expression of a subset of genes can be used to recover the full transcriptome, with important implications for biological discovery and clinical application. To address this challenge, we propose two novel deep learning methods, PMI and GAIN-GTEx, for gene expression imputation. In order to increase the applicability of our approach, we leverage data from GTEx v8, a reference resource that has generated a comprehensive collection of transcriptomes from a diverse set of human tissues. We show that our approaches compare favorably to several standard and state-of-the-art imputation methods in terms of predictive performance and runtime in two case studies and two imputation scenarios. In comparison conducted on the protein-coding genes, PMI attains the highest performance in inductive imputation whereas GAIN-GTEx outperforms the other methods in in-place imputation. Furthermore, our results indicate strong generalization on RNA-Seq data from 3 cancer types across varying levels of missingness. Our work can facilitate a cost-effective integration of large-scale RNA biorepositories into genomic studies of disease, with high applicability across diverse tissue types
Application of Laser Welding in Car Bodies Manufacturing
The paper deals with a problem of laser welding of zinc-coated steel (DX53D+Z and DX54D+Z) plates. Experiments were carried out with the use of steel plates 0.8; 1.0; 1.3; and 1.75 mm thick. High power 2.5-2.9 kW CO[2] laser was employed. CO[2] was used as the shielded gas. The optimal parameters of welding for material under study were determined. The mechanical properties of welded joints were measured through the tensile loading and microhardness measurement. Tensile performances of the specimens fabricated at different welding rate and laser beam power were compared with that of the base material
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