2,236 research outputs found
Erythrocyte complement receptor 1 (CR1) expression level is not associated with polymorphisms in the promoter or 3' untranslated regions of the CR1 gene
Complement receptor 1 (CR1) expression level on erythrocytes is genetically determined and is associated with high (H) and low (L) expression alleles identified by a HindIII restriction fragment-length polymorphism (RFLP) in intron 27 of the CR1 gene. The L allele confers protection against severe malaria in Papua New Guinea, probably because erythrocytes with low CR1 expression, are less able to form pathogenic rosettes with Plasmodium falciparum-infected erythrocytes. Despite the biological importance of erythrocyte CR1, the genetic mutation controlling CR1 expression level remains unknown. We investigated the possibility that mutations in the upstream or 3Ⲡuntranslated regions of the CR1 gene could control erythrocyte CR1 level. We identified several novel polymorphisms; however, the mutations did not segregate with erythrocyte CR1 expression level or the H and L alleles. Therefore, high and low erythrocyte CR1 levels cannot be explained by polymorphisms in transcriptional control elements in the upstream or 3Ⲡuntranslated regions of the CR1 gene
Simulating Turbulence Using the Astrophysical Discontinuous Galerkin Code TENET
In astrophysics, the two main methods traditionally in use for solving the
Euler equations of ideal fluid dynamics are smoothed particle hydrodynamics and
finite volume discretization on a stationary mesh. However, the goal to
efficiently make use of future exascale machines with their ever higher degree
of parallel concurrency motivates the search for more efficient and more
accurate techniques for computing hydrodynamics. Discontinuous Galerkin (DG)
methods represent a promising class of methods in this regard, as they can be
straightforwardly extended to arbitrarily high order while requiring only small
stencils. Especially for applications involving comparatively smooth problems,
higher-order approaches promise significant gains in computational speed for
reaching a desired target accuracy. Here, we introduce our new astrophysical DG
code TENET designed for applications in cosmology, and discuss our first
results for 3D simulations of subsonic turbulence. We show that our new DG
implementation provides accurate results for subsonic turbulence, at
considerably reduced computational cost compared with traditional finite volume
methods. In particular, we find that DG needs about 1.8 times fewer degrees of
freedom to achieve the same accuracy and at the same time is more than 1.5
times faster, confirming its substantial promise for astrophysical
applications.Comment: 21 pages, 7 figures, to appear in Proceedings of the SPPEXA
symposium, Lecture Notes in Computational Science and Engineering (LNCSE),
Springe
Historical roots of Agile methods: where did âAgile thinkingâ come from?
The appearance of Agile methods has been the most noticeable change to software process thinking in the last fifteen years [16], but in fact many of the âAgile ideasâ have been around since 70âs or even before. Many studies and reviews have been conducted about Agile methods which ascribe their emergence as a reaction against traditional methods. In this paper, we argue that although Agile methods are new as a whole, they have strong roots in the history of software engineering. In addition to the iterative and incremental approaches that have been in use since 1957 [21], people who criticised the traditional methods suggested alternative approaches which were actually Agile ideas such as the response to change, customer involvement, and working software over documentation. The authors of this paper believe that education about the history of Agile thinking will help to develop better understanding as well as promoting the use of Agile methods. We therefore present and discuss the reasons behind the development and introduction of Agile methods, as a reaction to traditional methods, as a result of people's experience, and in particular focusing on reusing ideas from histor
Phase coherence in quasicondensate experiments: an ab initio analysis via the stochastic Gross-Pitaevskii equation
We perform an ab initio analysis of the temperature dependence of the phase
coherence length of finite temperature, quasi-one-dimensional Bose gases
measured in the experiments of Richard et al. (Phys. Rev. Lett. 91, 010405
(2003)) and Hugbart et al. (Eur. Phys. J. D 35, 155-163 (2005)), finding very
good agreement across the entire observed temperature range
(). Our analysis is based on the one-dimensional stochastic
Gross-Pitaevskii equation, modified to self-consistently account for
transverse, quasi-one-dimensional effects, thus making it a valid model in the
regime . We also numerically implement an
alternative identification of , based on direct analysis of the
distribution of phases in a stochastic treatment.Comment: Amended manuscript with improved agreement to experiment, following
some additional clarifications by Mathilde Hugbart and Fabrice Gerbier and
useful comments by the reviewer; accepted for publication in Physical Review
Quantitative study of quasi-one-dimensional Bose gas experiments via the stochastic Gross-Pitaevskii equation
The stochastic Gross-Pitaevskii equation is shown to be an excellent model
for quasi-one-dimensional Bose gas experiments, accurately reproducing the in
situ density profiles recently obtained in the experiments of Trebbia et al.
[Phys. Rev. Lett. 97, 250403 (2006)] and van Amerongen et al. [Phys. Rev. Lett.
100, 090402 (2008)], and the density fluctuation data reported by Armijo et al.
[Phys. Rev. Lett. 105, 230402 (2010)]. To facilitate such agreement, we propose
and implement a quasi-one-dimensional stochastic equation for the low-energy,
axial modes, while atoms in excited transverse modes are treated as independent
ideal Bose gases.Comment: 10 pages, 5 figures; updated figures with experimental dat
Matter-wave dark solitons: stochastic vs. analytical results
The dynamics of dark matter-wave solitons in elongated atomic condensates are
discussed at finite temperatures. Simulations with the stochastic
Gross-Pitaevskii equation reveal a noticeable, experimentally observable spread
in individual soliton trajectories, attributed to inherent fluctuations in both
phase and density of the underlying medium. Averaging over a number of such
trajectories (as done in experiments) washes out such background fluctuations,
revealing a well-defined temperature-dependent temporal growth in the
oscillation amplitude. The average soliton dynamics is well captured by the
simpler dissipative Gross-Pitaevskii equation, both numerically and via an
analytically-derived equation for the soliton center based on perturbation
theory for dark solitons.Comment: 4 pages, 3 figures. Added several reference
Routine administration of oral polio vaccine in a subtropical area. Factors possibly influencing sero-conversion rates
Poliomyelitis is an important problem of public health in warm-climate countries. Studies of serological responses to vaccination in these countries have given conflicting results but in many investigations the rates have been considerably less than in countries with temperate climates. In this study three possible factors influencing sero-conversion were investigated - the season of the year when vaccine was given, the social status of the mother (as indicated by the number of years of schooling) and the presence of non-poliomyelitis viruses (NPV) in the gut when vaccine was given. Over 200 children about 2 months of age were included in the study. Each was given three doses of trivalent vaccine at 6-week intervals. The sero-conversion rates of the groups fed in winter were excellent but were slightly less good in summer. The differences were greatest in children in the lower socio-economic groups and in children excreting other enteroviruses. The conclusions are that, provided a potent vaccine is used, the factors which diminish the effectiveness of immunization in warm-climate countries can be overcome: (1) by giving three doses of trivalent vaccine; (2) by beginning vaccination at the earliest possible age (when enteroviruses are fewest); (3) by concentrating special attention on the lower socio-economic groups and if necessary by giving a reinforcing dose several months after the third dose has been given - preferably in the colder month
Discontinuous Galerkin method for multifluid Euler equations
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106454/1/AIAA2013-2595.pd
Agile methods for agile universities
We explore a term, Agile, that is being used in various workplace settings, including the management of universities. The term may have several related but slightly different meanings. Agile is often used in the context of facilitating more creative problem-solving and advocating for the adoption, design, tailoring and continual updating of more innovative organizational processes. We consider a particular set of meanings of the term from the world of software development. Agile methods were created to address certain problems with the software development process. Many of those problems have interesting analogues in the context of universities, so a reflection on agile methods may be a useful heuristic for generating ideas for enabling universities to be more creative
- âŚ