90,890 research outputs found

    Parallel Implementation of the PHOENIX Generalized Stellar Atmosphere Program. II: Wavelength Parallelization

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    We describe an important addition to the parallel implementation of our generalized NLTE stellar atmosphere and radiative transfer computer program PHOENIX. In a previous paper in this series we described data and task parallel algorithms we have developed for radiative transfer, spectral line opacity, and NLTE opacity and rate calculations. These algorithms divided the work spatially or by spectral lines, that is distributing the radial zones, individual spectral lines, or characteristic rays among different processors and employ, in addition task parallelism for logically independent functions (such as atomic and molecular line opacities). For finite, monotonic velocity fields, the radiative transfer equation is an initial value problem in wavelength, and hence each wavelength point depends upon the previous one. However, for sophisticated NLTE models of both static and moving atmospheres needed to accurately describe, e.g., novae and supernovae, the number of wavelength points is very large (200,000--300,000) and hence parallelization over wavelength can lead both to considerable speedup in calculation time and the ability to make use of the aggregate memory available on massively parallel supercomputers. Here, we describe an implementation of a pipelined design for the wavelength parallelization of PHOENIX, where the necessary data from the processor working on a previous wavelength point is sent to the processor working on the succeeding wavelength point as soon as it is known. Our implementation uses a MIMD design based on a relatively small number of standard MPI library calls and is fully portable between serial and parallel computers.Comment: AAS-TeX, 15 pages, full text with figures available at ftp://calvin.physast.uga.edu/pub/preprints/Wavelength-Parallel.ps.gz ApJ, in pres

    A review of acute bacterial meningitis in childhood

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    This paper reviews the epidemiology, pathogenesis and management of acute bacterial meningitis in childhood. The epidemiology of this infection has undergone significant changes with the implementation of effective immunisation, antibiotic therapy and chemoprophylaxis. The reported incidence of bacterial meningitis in children in the Maltese Islands is low compared to other countries. A high index of suspicion is required to diagnose the onset of bacterial meningitis especially in infants. Third-generation cephalosporins are currently the antibiotics of choice for the acute disease. The timely administration of penicillin may be life saving in cases of meningococcal septicaemia. Adjuvant therapy such as dexamethasone may reduce the occurrence and the severity of sequelae, in particular sensorineural hearing loss. Chemoprophylaxis with rifampicin has played an important role in curtailing epidemics of meningococcal disease. The Haemophilus influenzae type b (Hib) vaccine has made a significant impact on the incidence of H. influenzae meningitis in children. Effective vaccines against pneumococci and meningococci (type b) do not yet exist, however ongoing research seeks to produce these vaccines in an effort to emulate the successful outcome attained by the Hib vaccine.peer-reviewe

    Officer-Involved Domestic Violence: The Mediating Factors

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    Domestic and family violence has been a critical issue in contemporary society. Efforts have been made in researching the causes, effects, and mediating factors of domestic violence in relation to the workplace. Studies demonstrate that a relationship between conflict crossing over from the work to the home environment exist. Additional studies demonstrate that domestic violence does affect the workplace; however, there is little to no scientific data on the reverse relationship. The reverse relationship regards whether the workplace affects the occurrence of domestic violence. This research paper will dive into this topic, and on the lack of data available. Supporting data will illustrate that factors from the workplace do affect the likelihood of domestic and/or family violence occurring in police families. Not considering or viewing police family violence as an effect of workplace factors is shortsighted, and it demonstrates the need for education on this topic. With new data, comes new policies and implications that are reconfigurations of the existing policies. There is a need to bring this subject to light, and in view of the law enforcement community

    A Formal Apology for Metaphysics

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    There is an old meta-philosophical worry: very roughly, metaphysical theories have no observational consequences and so the study of metaphysics has no value. The worry has been around in some form since the rise of logical positivism in the early twentieth century but has seen a bit of a renaissance recently. In this paper, I provide an apology for metaphysics in the face of this kind of concern. The core of the argument is this: pure mathematics detaches from science in much the same manner as metaphysics and yet it is valuable nonetheless. The source of value enjoyed by pure mathematics extends to metaphysics as well. Accordingly, if one denies that metaphysics has value, then one is forced to deny that pure mathematics has value. The argument places an added burden on the sceptic of metaphysics. If one truly believes that metaphysics is worthless (as some philosophers do), then one must give up on pure mathematics as well
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