4,066 research outputs found

    Centrifugally Obtained Artificial Gravity

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    Centrifugally obtained artificial gravity effects on space station crew performanc

    A transport properties of a moderately dense lennard-jones gas

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    First and second order density corrections to transport coefficients of moderately dense ga

    The compatible conversion system

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    Compatible conversion system centralizes the solution of general problems arising from the use of direct access mass storage. It also provides a simple stable interface for the conversion of production programs to process on third generation computer system

    FEniCS-HPC: Automated predictive high-performance finite element computing with applications in aerodynamics

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    Developing multiphysics finite element methods (FEM) and scalable HPC implementations can be very challenging in terms of software complexity and performance, even more so with the addition of goal-oriented adaptive mesh refinement. To manage the complexity we in this work present general adaptive stabilized methods with automated implementation in the FEniCS-HPC automated open source software framework. This allows taking the weak form of a partial differential equation (PDE) as input in near-mathematical notation and automatically generating the low-level implementation source code and auxiliary equations and quantities necessary for the adaptivity. We demonstrate new optimal strong scaling results for the whole adaptive framework applied to turbulent flow on massively parallel architectures down to 25000 vertices per core with ca. 5000 cores with the MPI-based PETSc backend and for assembly down to 500 vertices per core with ca. 20000 cores with the PGAS-based JANPACK backend. As a demonstration of the power of the combination of the scalability together with the adaptive methodology allowing prediction of gross quantities in turbulent flow we present an application in aerodynamics of a full DLR-F11 aircraft in connection with the HiLift-PW2 benchmarking workshop with good match to experiments

    Deep near-infrared imaging of the HE0450-2958 system

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    The QSO HE0450-2958 and the companion galaxy with which it is interacting, both ultra luminous in the infrared, have been the subject of much attention in recent years, as the quasar host galaxy remained undetected. This led to various interpretations on QSO and galaxy formation and co-evolution, such as black hole ejection, jet induced star formation, dust obscured galaxy, or normal host below the detection limit. We carried out deep observations in the near-IR in order to solve the puzzle concerning the existence of any host. The object was observed with the ESO VLT and HAWK-I in the near-IR J-band for 8 hours. The images have been processed with the MCS deconvolution method (Magain, Courbin & Sohy, 1998), permitting accurate subtraction of the QSO light from the observations. The compact emission region situated close to the QSO, called the blob, which previously showed only gas emission lines in the optical spectra, is now detected in our near-IR images. Its high brightness implies that stars likely contribute to the near-IR emission. The blob might thus be interpreted as an off-centre, bright and very compact host galaxy, involved in a violent collision with its companion.Comment: 4 pages, 3 figures, accepted for publication in A&

    Assessment of Peer-Based and Structural Strategies for Increasing Male Participation in an Antenatal Setting in Lilongwe, Malawi

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    In sub-Saharan Africa, although male involvement in antenatal care is associated with positive outcomes for HIV-infected women and their  infants, men rarely accompany female partners. We implemented a project to increase the number of male partners attending an antenatal clinic at Bwaila Hospital in Lilongwe, Malawi. We evaluated changes in the  proportion of women who came with a partner over three periods. During period 1 (January 2007 – June 2008) there was didactic peer education. During period 2 (July 2008 – September 2009) a peer-led   male-involvement drama was introduced into patient waiting areas. During period 3 (October 2009 – December 2009) changes to clinical infrastructure were introduced to make the clinic more male-friendly. The proportion of women attending ANC with a male partner increased from 0.7% to 5.7% to 10.7% over the three periods. Peer education through drama and  male-friendly hospital infrastructure coincided with substantially greater male participation, although further gains are necessary. Afr J Reprod Health 2014; 18[2]: 97-104).Keywords: HIV, antenatal, male involvement, HIV counseling and testing, disclosure, prevention of mother to child transmission, coupl

    Visualizing the microscopic coexistence of spin density wave and superconductivity in underdoped NaFe1-xCoxAs

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    Although the origin of high temperature superconductivity in the iron pnictides is still under debate, it is widely believed that magnetic interactions or fluctuations play an important role in triggering Cooper pairing. Because of the relevance of magnetism to pairing, the question of whether long range spin magnetic order can coexist with superconductivity microscopically has attracted strong interests. The available experimental methods used to answer this question are either bulk probes or local ones without control of probing position, thus the answers range from mutual exclusion to homogeneous coexistence. To definitively answer this question, here we use scanning tunneling microscopy to investigate the local electronic structure of an underdoped NaFe1-xCoxAs near the spin density wave (SDW) and superconducting (SC) phase boundary. Spatially resolved spectroscopy directly reveal both the SDW and SC gap features at the same atomic location, providing compelling evidence for the microscopic coexistence of the two phases. The strengths of the SDW and SC features are shown to anti correlate with each other, indicating the competition of the two orders. The microscopic coexistence clearly indicates that Cooper pairing occurs when portions of the Fermi surface (FS) are already gapped by the SDW order. The regime TC < T < TSDW thus show a strong resemblance to the pseudogap phase of the cuprates where growing experimental evidences suggest a FS reconstruction due to certain density wave order. In this phase of the pnictides, the residual FS has a favorable topology for magnetically mediated pairing when the ordering moment of the SDW is small.Comment: 18 pages, 4 figure

    Novel mutation identification and copy number variant detection via exome sequencing in congenital muscular dystrophy.

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    BACKGROUND: Congenital muscular dystrophy type 1A (MDC1A), also termed merosin-deficient congenital muscular dystrophy (CMD), is a severe form of CMD caused by mutations in the laminin α2 gene (LAMA2). Of the more than 300 likely pathogenic variants found in the Leiden Open Variant Database, the majority are truncating mutations leading to complete LAMA2 loss of function, but multiple copy number variants (CNVs) have also been reported with variable frequency. METHODS: We collected a cohort of individuals diagnosed with likely MDC1A and sought to identify both single nucleotide variants and small and larger CNVs via exome sequencing by extending the analysis of sequencing data to detect splicing changes and CNVs. RESULTS: Standard exome analysis identified multiple novel LAMA2 variants in our cohort, but only four cases carried biallelic variants. Since likely truncating LAMA2 variants are often found in heterozygosity without a second allele, we performed additional splicing and CNV analysis on exome data and identified one splice change outside of the canonical sequences and three CNVs, in the remaining four cases. CONCLUSIONS: Our findings support the expectation that a portion of MDC1A cases may be caused by at least one CNV allele and show how these changes can be effectively identified by additional analysis of existing exome data

    Evaluating the benefits of incorporating traditional birth attendants in HIV Prevention of Mother to Child Transmission service delivery in Lilongwe, Malawi

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    The objective of our intervention was to examine the benefits of incorporating traditional birth attendants (TBA) in HIV Prevention of Mother to Child Transmission (PMTCT) service delivery. We developed a training curriculum for TBAs related to PMTCT and current TBA roles in Malawi. Fourteen TBAs and seven TBA assistants serving 4 urban health centre catchment areas were assessed, trained and supervised. Focus group discussions with the TBAs were conducted after implementation of the program. From March 2008 to August 2009, a total of 4017 pregnant women visited TBAs, out of which 2133 (53.1%) were directly referred to health facilities and 1,884 (46.9%) women delivered at TBAs and subsequently referred. 168 HIV positive women were identified by TBAs. Of these, 86/168 (51.2%) women received nevirapine and 46/168 (27.4%) HIV exposed infants received nevirapine. The challenges in providing PMTCT services included lack of transportation for referrals and absence of a reporting system to confirm the woman’s arrival at the health center. Non-disclosure of HIV status by patients to the TBAs resulted in inability to assist nevirapine uptake. TBAs, when trained and well-supervised, can supplement efforts to provide PMTCT services in communities. (Afr J Reprod Health 2014; 18[1]: 27-34).Keywords: Traditional Birth Attendants, PMTCT, Malaw

    Lepton Acceleration in Pulsar Wind Nebulae

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    Pulsar Wind Nebulae (PWNe) act as calorimeters for the relativistic pair winds emanating from within the pulsar light cylinder. Their radiative dissipation in various wavebands is significantly different from that of their pulsar central engines: the broadband spectra of PWNe possess characteristics distinct from those of pulsars, thereby demanding a site of lepton acceleration remote from the pulsar magnetosphere. A principal candidate for this locale is the pulsar wind termination shock, a putatively highly-oblique, ultra-relativistic MHD discontinuity. This paper summarizes key characteristics of relativistic shock acceleration germane to PWNe, using predominantly Monte Carlo simulation techniques that compare well with semi-analytic solutions of the diffusion-convection equation. The array of potential spectral indices for the pair distribution function is explored, defining how these depend critically on the parameters of the turbulent plasma in the shock environs. Injection efficiencies into the acceleration process are also addressed. Informative constraints on the frequency of particle scattering and the level of field turbulence are identified using the multiwavelength observations of selected PWNe. These suggest that the termination shock can be comfortably invoked as a principal injector of energetic leptons into PWNe without resorting to unrealistic properties for the shock layer turbulence or MHD structure.Comment: 19 pages, 5 figures, invited review to appear in Proc. of the inaugural ICREA Workshop on "The High-Energy Emission from Pulsars and their Systems" (2010), eds. N. Rea and D. Torres, (Springer Astrophysics and Space Science series
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