Detecting collisions in sets of moving particles: a survey and some experiments

Detecting and responding to collisions between particles is an important requirement for building simulations in computational science. Due to the large number of potential collisions it is impractical to check all possibilities, so the development of algorithms which narrow down the number of possible searches to a small number is important. In this paper we review various algorithms for this task, and give results from a number of experiments which demonstrate the relative efficiency of these algorithms on a fundamental problem of detecting collisions between particles undergoing Brownian motion. The general slant of the paper is towards the development of algorithms for simulating microbiological systems

Using participatory research and gender analysis in natural resource management

The use of participatory tools and methods has increased dramatically in natural resource management (NRM) over the past decade, largely because of the recognition that sustainable NRM cannot be achieved without involving the individuals and communities who make decisions about how resources are used. Participation of resource users and other stakeholders is important not only in the management of resources, but also in research oriented toward the generation of information and innovations that shape how resources are understood and exploited. Although there is extensive literature on participatory tools and methods and a growing number of case studies of their use in NRM (Hinchcliffe et al; IDRC; Pretty), it is difficult to form a coherent overview of this body of work, much of which is unpublished. Moreover, the distinction between participatory research and participatory management is seldom made, either in case studies or in the guides to tools and methods. Yet participatory management that is not firmly linked to research—understood as a process of knowledge generation that supports technical and institutional innovation—is often hindered by a lack of new technical options, information and institutions. There has been little systematic analysis of how participatory research (PR) methods and gender/stakeholder analysis (GSA) are being used in NRM research. 1 This study begins to fill the gap by providing a comparative analysis of over 60 participatory NRM research projects compiled by the Systemwide Program on Participatory Research and Gender Analysis (PRGA). The paper looks at who is doing PR research and GSA in NRM, where, how and with what observed or expected impact. Projects are assessed in terms of the type of participation they use, how they select participants, and whom they target as beneficiaries. The costs and benefits associated with incorporating user participation are also analyzed

POWERLIB: SAS/IML Software for Computing Power in Multivariate Linear Models

The POWERLIB SAS/IML software provides convenient power calculations for a wide range of multivariate linear models with Gaussian errors. The software includes the Box, Geisser-Greenhouse, Huynh-Feldt, and uncorrected tests in the "univariate" approach to repeated measures (UNIREP), the Hotelling Lawley Trace, Pillai-Bartlett Trace, and Wilks Lambda tests in "multivariate" approach (MULTIREP), as well as a limited but useful range of mixed models. The familiar univariate linear model with Gaussian errors is an important special case. For estimated covariance, the software provides confidence limits for the resulting estimated power. All power and confidence limits values can be output to a SAS dataset, which can be used to easily produce plots and tables for manuscripts.

The Role of Chronic Psychosocial Stress in Explaining Racial Differences in Stress Reactivity and Pain Sensitivity

To examine the role of psychosocial factors in mediating the relationship between African American (AA) race and both increased pain sensitivity and blunted stress reactivity

POWERLIB: SAS/IML Software for Computing Power in Multivariate Linear Models

The POWERLIB SAS/IML software provides convenient power calculations for a wide range of multivariate linear models with Gaussian errors. The software includes the Box, Geisser-Greenhouse, Huynh-Feldt, and uncorrected tests in the "univariate" approach to repeated measures (UNIREP), the Hotelling Lawley Trace, Pillai-Bartlett Trace, and Wilks Lambda tests in "multivariate" approach (MULTIREP), as well as a limited but useful range of mixed models. The familiar univariate linear model with Gaussian errors is an important special case. For estimated covariance, the software provides confidence limits for the resulting estimated power. All power and confidence limits values can be output to a SAS dataset, which can be used to easily produce plots and tables for manuscripts

Histories of abuse predict stronger within-person covariation of ovarian steroids and mood symptoms in women with menstrually related mood disorder

Individual differences in sensitivity to cyclical changes in ovarian steroids estradiol (E2) and progesterone (P4) have been implicated in the pathophysiology of menstrually related mood disorder (MRMD). However, no prospective studies have investigated psychosocial risk factors for sensitivity to hormone effects on mood in MRMD. Using a repeated measures approach and multilevel models, we tested the hypothesis that a history of abuse provides a context in which within-person elevations of E2 and P4 prospectively predict daily symptoms

Role of copper efflux in pneumococcal pathogenesis and resistance to macrophage-mediated immune clearance

In bacteria, the intracellular levels of metals are mediated by tightly controlled acquisition and efflux systems. This is particularly true of copper, a trace element that is universally toxic in excess. During infection, the toxic properties of copper are exploited by the mammalian host to facilitate bacterial clearance. To better understand the role of copper during infection, we characterized the contribution of the cop operon to copper homeostasis and virulence in Streptococcus pneumoniae. Deletion of either the exporter, encoded by copA, or the chaperone, encoded by cupA, led to hypersensitivity to copper stress. We further demonstrated that loss of the copper exporter encoded by copA led to decreased virulence in pulmonary, intraperitoneal, and intravenous models of infection. Deletion of copA resulted in enhanced macrophage-mediated bacterial clearance in vitro. The attenuation phenotype of the copA mutant in the lung was found to be dependent on pulmonary macrophages, underscoring the importance of copper efflux in evading immune defenses. Overall, these data provide insight into the role of the cop operon in pneumococcal pathogenesis

Toward the Reliable Diagnosis of DSM-5 Premenstrual Dysphoric Disorder: The Carolina Premenstrual Assessment Scoring System (C-PASS)

Despite evidence for the validity of premenstrual dysphoric disorder (PMDD) and its recent inclusion in DSM-5, variable diagnostic practices compromise the construct validity of the diagnosis and threaten the clarity of efforts to understand and treat its underlying pathophysiology. In an effort to hasten and streamline the translation of the new DSM-5 criteria for PMDD into terms compatible with existing research practices, we present the development and initial validation of the Carolina Premenstrual Assessment Scoring System (C-PASS). The C-PASS is a standardized scoring system for making DSM-5 PMDD diagnoses using 2 or more menstrual cycles of daily symptom ratings using the Daily Record of Severity of Problems (DRSP)