Improving Simulations of MPI Applications Using A Hybrid Network Model with Topology and Contention Support

Proper modeling of collective communications is essential for understanding the behavior of medium-to-large scale parallel applications, and even minor deviations in implementation can adversely affect the prediction of real-world performance. We propose a hybrid network model extending LogP based approaches to account for topology and contention in high-speed TCP networks. This model is validated within SMPI, an MPI implementation provided by the SimGrid simulation toolkit. With SMPI, standard MPI applications can be compiled and run in a simulated network environment, and traces can be captured without incurring errors from tracing overheads or poor clock synchronization as in physical experiments. SMPI provides features for simulating applications that require large amounts of time or resources, including selective execution, ram folding, and off-line replay of execution traces. We validate our model by comparing traces produced by SMPI with those from other simulation platforms, as well as real world environments.Une bonne modélisation des communications collective est indispensable à la compréhension des performances des applications parallèles et des différences, même minimes, dans leur implémentation peut drastiquement modifier les performances escomptées. Nous proposons un modèle réseau hybrid étendant les approches de type LogP mais permettant de rendre compte de la topologie et de la contention pour les réseaux hautes performances utilisant TCP. Ce modèle est mis en oeuvre et validé au sein de SMPI, une implémentation de MPI fournie par l'environnement SimGrid. SMPI permet de compiler et d'exécuter sans modification des applications MPI dans un environnement simulé. Il est alors possible de capturer des traces sans l'intrusivité ni les problème de synchronisation d'horloges habituellement rencontrés dans des expériences réelles. SMPI permet également de simuler des applications gourmandes en mémoire ou en temps de calcul à l'aide de techniques telles l'exécution sélective, le repliement mémoire ou le rejeu hors-ligne de traces d'exécutions. Nous validons notre modèle en comparant les traces produites à l'aide de SMPI avec celles de traces d'exécution réelle. Nous montrons le gain obtenu en les comparant également à celles obtenues avec des modèles plus classiques utilisés dans des outils concurrents

Sources of Stress and Their Associations With Mental Disorders Among College Students: Results of the World Health Organization World Mental Health Surveys International College Student Initiative

The college years are stressful for many students. Identifying the sources of stress and their relative importance in leading to clinically significant emotional problems may assist in the development of targeted stress management interventions. The current report examines the distribution and associations of perceived stress across major life areas with 12-month prevalence of common mental disorders in a cross-national sample of first-year college students. The 20,842 respondents were from 24 universities in 9 countries that participated in the World Health Organization World Mental Health International College Student Initiative. Logistic regression analysis examined associations of current perceived stress in six life areas (financial situation, health, love life, relationships with family, relationships at work/school, problems experienced by loved ones) with six types of 12-month mental disorders (major depressive disorder, bipolar disorder, generalized anxiety disorder, panic disorder, alcohol use disorder, drug use disorder). Population attributable risk proportions (PARPs) were calculated to estimate the upper-bound potential effects of interventions focused on perceived stress in reducing prevalence of mental disorders. The majority of students (93.7%) reported at least some stress in at least one of the six areas. A significant dose-response association was found between extent of stress in each life area and increased odds of at least one of the six disorders. The multivariable models that included all stress measures were significant for all disorders (F = 20.6-70.6, p < 0.001). Interpretation of PARPs as representing causal effects of stresses on disorders suggests that up to 46.9-80.0% of 12-month disorder prevalence might be eliminated if stress prevention interventions were developed to block the associations of stress with these disorders.status: publishe

The incidence of Kawasaki disease using hospital admissions data for England 2006-2021

To describe the incidence of Kawasaki Disease (kDa) between 2006 and 2021 in England. We identified all cases in hospital episode statistics with an ICD-10 diagnostic code M303 (for kDa) between 1 April 2006 - 31 March 2021. We validated 83 diagnoses using hospital medical records and found >97% accuracy. We calculated incidence rate ratios (IRRs) using Poisson regression and assessed the influence of age, sex, ethnicity, and index of multiple deprivation (IMD). We used Office for National Statistics population estimates for England as the denominator. We identified a total of 5908 cases of kDa in all children under the age of 16 (mean age 3.8, SD = 3.2, 95% CI: 3.7-3.9). Incidence in children aged <5 years was 8.9 (95% CI: 8.6-9.2)/100 000 person-years; in children aged 5-9, 2.4 (95% CI: 2.3-2.6)/100 000 person-years; and in children aged 10-15, 0.6 (95% CI: 0.6-0.7). Male: female ratio was 1.5:1. Incidence was higher among non-White than White ethnicities (adjusted IRR 2.1 (2.0-2.2) for Asian, 3.0 (2.8-3.3) for Black and 4.5 (4.2-4.8) for other ethnicities). The incidence increased with socioeconomic deprivation; the adjusted IRR of the least deprived IMD quintile compared with the most deprived quintile was 0.81 (0.77-0.84). Incidence rates of kDa derived from hospital admission data in England were higher than in studies relying on clinician reporting. We confirm previous findings on the influence of sex, and ethnicity on kDa incidence and observe that there was a higher incidence of kDa within more deprived socioeconomic groups

Incorporation of a Dietary Omega 3 Fatty Acid Impairs Murine Macrophage Responses to Mycobacterium tuberculosis

by creating an immunosuppressive environment. We hypothesized that incorporation of n-3 PUFA suppresses activation of macrophage antimycobacterial responses and favors bacterial growth, in part, by modulating the IFNγ-mediated signaling pathway.. The fatty acid composition of macrophage membranes was modified significantly by DHA treatment. DHA-treated macrophages were less effective in controlling intracellular mycobacteria and showed impaired oxidative metabolism and reduced phagolysosome maturation. Incorporation of DHA resulted in defective macrophage activation, as characterized by reduced production of pro-inflammatory cytokines (TNFα, IL-6 and MCP-1), and lower expression of co-stimulatory molecules (CD40 and CD86). DHA treatment impaired STAT1 phosphorylation and colocalization of the IFNγ receptor with lipid rafts, without affecting surface expression of IFNγ receptor. in response to activation by IFNγ, by modulation of IFNγ receptor signaling and function, suggesting that n-3 PUFA-enriched diets may have a detrimental effect on host immunity to tuberculosis

The internal migration propensities and net migration patterns of ethnic groups in Britain

Internal migration propensities of ethnic groups are examined using three types of census data. Special Migration Statistics show variation in aggregate propensities whereas commissioned age-specific flow data indicate age variations by ethnic group. Micro data from Samples of Anonyms Records confirm low Asian propensities and suggest convergence between 1991 and 2001. Inter-district net migration reveals familiar counter urbanisation trends for whites but more complex patterns for non-whites. Evidence suggests white net migration at this scale is greater in areas with higher non-white population shares which themselves experience higher non-white immigration rates.ethnic populations; whites; non-whites; internal migration; England; Wales; Britain