164 research outputs found
Square patterns in Rayleigh-Benard convection with rotation about a vertical axis
We present experimental results for Rayleigh-Benard convection with rotation
about a vertical axis at dimensionless rotation rates in the range 0 to 250 and
upto 20% above the onset. Critical Rayleigh numbers and wavenumbers agree with
predictions of linear stability analysis. For rotation rates greater than 70
and close to onset, the patterns are cellular with local four-fold coordination
and differ from the theoretically expected Kuppers-Lortz unstable state. Stable
as well as intermittent defect-free square lattices exist over certain
parameter ranges. Over other ranges defects dynamically disrupt the lattice but
cellular flow and local four-fold coordination is maintained.Comment: ReVTeX, 4 pages, 7 eps figures include
Effect of Phosphorus Amendments on Present Day Plankton Communities in Pelagic Lake Erie
To address questions regarding the potential impact of elevated total phosphorus (TP) inputs (due to relaxed regulations of TP loading), a series of TP enrichment experiments were conducted at pelagic stations in the 3 hydrologically distinct basins of Lake Erie. Results of nutrient assimilation measurements and assays for nutrient bioavailability suggest that the chemical speciation, and not concentration, of nitrogenous compounds may influence phytoplankton community structure; this in turn may lead to the selective proliferation of cyanobacteria in the eastern basin of the lake. Assays with cyanobacterial bioluminescent reporter systems for P and N availability as well as N-tot:P-tot assimilation ratios from on-deck incubation experiments support this work. Considered in the context of a microbial food web relative to a grazing food web, the results imply that alterations in current TP loading controls may lead to alterations in the phytoplankton community structure in the different basins of the Lake Erie system
A Continuum Description of Vibrated Sand
The motion of a thin layer of granular material on a plate undergoing
sinusoidal vibrations is considered. We develop equations of motion for the
local thickness and the horizontal velocity of the layer. The driving comes
from the violent impact of the grains on the plate. A linear stability theory
reveals that the waves are excited non-resonantly, in contrast to the usual
Faraday waves in liquids. Together with the experimentally observed continuum
scaling, the model suggests a close connection between the neutral curve and
the dispersion relation of the waves, which agrees quite well with experiments.
For strong hysteresis we find localized oscillon solutions.Comment: paper has been considerably extended (11 instead of 6 pages; 6
instead of 4 figures) much better agreement with experiment. obtain now
oscillons in 1 dimensio
Widespread detection of highly pathogenic H5 influenza viruses in wild birds from the Pacific Flyway of the United States
A novel highly pathogenic avian influenza virus belonging to the H5 clade 2.3.4.4 variant viruses was detected in North America in late 2014. Motivated by the identification of these viruses in domestic poultry in Canada, an intensive study was initiated to conduct highly pathogenic avian influenza surveillance in wild birds in the Pacific Flyway of the United States. A total of 4,729 hunter-harvested wild birds were sampled and highly pathogenic avian influenza virus was detected in 1.3% (n = 63). Three H5 clade 2.3.4.4 subtypes were isolated from wild birds, H5N2, H5N8, and H5N1, representing the wholly Eurasian lineage H5N8 and two novel reassortant viruses. Testing of 150 additional wild birds during avian morbidity and mortality investigations in Washington yielded 10 (6.7%) additional highly pathogenic avian influenza isolates (H5N8 = 3 and H5N2 = 7). The geographically widespread detection of these viruses in apparently healthy wild waterfowl suggest that the H5 clade 2.3.4.4 variant viruses may behave similarly in this taxonomic group whereby many waterfowl species are susceptible to infection but do not demonstrate obvious clinical disease. Despite these findings in wild waterfowl, mortality has been documented for some wild bird species and losses in US domestic poultry during the first half of 2015 were unprecedented
Development of the Migrant Friendly Maternity Care Questionnaire (MFMCQ) for migrants to Western societies: an international Delphi consensus process
Background
Through the World Health Assembly Resolution, ‘Health of Migrants’, the international community has identified migrant health as a priority. Recommendations for general hospital care for international migrants in receiving-countries have been put forward by the Migrant Friendly Hospital Initiative; adaptations of these recommendations specific to maternity care have yet to be elucidated and validated. We aimed to develop a questionnaire measuring migrant-friendly maternity care (MFMC) which could be used in a range of maternity care settings and countries.
Methods
This study was conducted in four stages. First, questions related to migrant friendly maternity care were identified from existing questionnaires including the Migrant Friendliness Quality Questionnaire, developed in Europe to capture recommended general hospital care for migrants, and the Mothers In a New Country (MINC) Questionnaire, developed in Australia and revised for use in Canada to capture the maternity care experiences of migrant women, and combined to create an initial MFMC questionnaire. Second, a Delphi consensus process in three rounds with a panel of 89 experts in perinatal health and migration from 17 countries was undertaken to identify priority themes and questions as well as to clarify wording and format. Third, the draft questionnaire was translated from English to French and Spanish and back-translated and subsequently culturally validated (assessed for cultural appropriateness) by migrant women. Fourth, the questionnaire was piloted with migrant women who had recently given birth in Montreal, Canada.
Results
A 112-item questionnaire on maternity care from pregnancy, through labour and birth, to postpartum care, and including items on maternal socio-demographic, migration and obstetrical characteristics, and perceptions of care, has been created - the Migrant Friendly Maternity Care Questionnaire (MFMCQ) – in three languages (English, French and Spanish). It is completed in 45 minutes via interview administration several months post-birth.
Conclusions
A 4-stage process of questionnaire development with international experts in migrant reproductive health and research resulted in the MFMCQ, a questionnaire measuring key aspects of migrant-sensitive maternity care. The MFMCQ is available for further translation and use to examine and compare care and perceptions of care within and across countries, and by key socio-demographic, migration, and obstetrical characteristics of migrant women
Reconstruction and identification of τ lepton decays to hadrons and ντ at CMS
This paper describes the algorithms used by the CMS experiment to reconstruct and identify τ → hadrons + νtau; decays during Run 1 of the LHC. The performance of the algorithms is studied in proton-proton collisions recorded at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. The algorithms achieve an identification efficiency of 50-60%, with misidentification rates for quark and gluon jets, electrons, and muons between per mille and per cent levels
Characteristics of HIV-1 Discordant Couples Enrolled in a Trial of HSV-2 Suppression to Reduce HIV-1 Transmission: The Partners Study
Background: The Partners HSV-2/HIV-1 Transmission Study (Partners Study) is a phase III, placebo-controlled trial of daily acyclovir for genital herpes (HSV-2) suppression among HIV-1/HSV-2 co-infected persons to reduce HIV-1 transmission to their HIV-1 susceptible partners, which requires recruitment of HIV-1 serodiscordant heterosexual couples. We describe the baseline characteristics of this cohort. Methods: HIV-1 serodiscordant heterosexual couples, in which the HIV-1 infected partner was HSV-2 seropositive, had a CD4 count ≥250 cells/mcL and was not on antiretroviral therapy, were enrolled at 14 sites in East and Southern Africa. Demographic, behavioral, clinical and laboratory characteristics were assessed. Results: Of the 3408 HIV-1 serodiscordant couples enrolled, 67% of the HIV-1 infected partners were women. Couples had cohabitated for a median of 5 years (range 2–9) with 28% reporting unprotected sex in the month prior to enrollment. Among HIV-1 susceptible participants, 86% of women and 59% of men were HSV-2 seropositive. Other laboratory-diagnosed sexually transmitted infections were uncommon (500 relative to <350, respectively, p<0.001). Conclusions: The Partners Study successfully enrolled a cohort of 3408 heterosexual HIV-1 serodiscordant couples in Africa at high risk for HIV-1 transmission. Follow-up of this cohort will evaluate the efficacy of acyclovir for HSV-2 suppression in preventing HIV-1 transmission and provide insights into biological and behavioral factors determining heterosexual HIV-1 transmission. Trial Registration ClinicalTrials.gov NCT0019451
Influenza vaccination for immunocompromised patients: systematic review and meta-analysis from a public health policy perspective.
Immunocompromised patients are vulnerable to severe or complicated influenza infection. Vaccination is widely recommended for this group. This systematic review and meta-analysis assesses influenza vaccination for immunocompromised patients in terms of preventing influenza-like illness and laboratory confirmed influenza, serological response and adverse events
Motion speed modulates walking direction discrimination: The role of the feet in biological motion perception
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