147 research outputs found
Dynamical Blueprints for Galaxies
We present an axisymmetric, equilibrium model for late-type galaxies which
consists of an exponential disk, a Sersic bulge, and a cuspy dark halo. The
model is specified by a phase space distribution function which, in turn,
depends on the integrals of motion. Bayesian statistics and the Markov Chain
Monte Carlo method are used to tailor the model to satisfy observational data
and theoretical constraints. By way of example, we construct a chain of 10^5
models for the Milky Way designed to fit a wide range of photometric and
kinematic observations. From this chain, we calculate the probability
distribution function of important Galactic parameters such as the Sersic index
of the bulge, the disk scale length, and the disk, bulge, and halo masses. We
also calculate the probability distribution function of the local dark matter
velocity dispersion and density, two quantities of paramount significance for
terrestrial dark matter detection experiments.
Though the Milky Way models in our chain all satisfy the prescribed
observational constraints, they vary considerably in key structural parameters
and therefore respond differently to non-axisymmetric perturbations. We
simulate the evolution of twenty-five models which have different Toomre Q and
Goldreich-Tremaine X parameters. Virtually all of these models form a bar,
though some, more quickly than others. The bar pattern speeds are ~ 40 - 50
km/s/kpc at the time when they form and then decrease, presumably due to
coupling of the bar with the halo. Since the Galactic bar has a pattern speed
~50 km/s/kpc we conclude that it must have formed recently.Comment: 54 pages, 20 figure
The Reasons of the House of Commons. to Stay the Qveenes Going into Holland, Delivered to the Lords, at a Conference the 14 of Iuly. / by Iohn Pymme Esq; Delivered the 15. to His Maiesty, in Presence of Both Houses, by My Lord Bankes
https://openworks.wooster.edu/notestein/1025/thumbnail.jp
Module Homomorphisms and Topological Centres Associated with Weakly Sequentially Complete Banach Algebras
AbstractThis paper is a contribution to the theory of weakly sequentially complete Banach algebrasA. We require them to have bounded approximate identities and, for the most part, to be ideals in their second duals, so that examples are the group algebrasL1(G) for compact groupsGor the Fourier algebrasA(G) for discrete amenable groupsG. In Section 2 we present our main result, that the topological centre (or set of weak* bicontinuous elements) ofA** is identifiable withA. As a corollary, we deduce in Section 3 that each leftA-module homomorphism fromA* toA*Acan be realized as right translation by an element ofA. These conclusions generalise recent advances in the subject. In Section 4 we take a special algebra,l1(S) for a commutative discrete semigroupS, and show that if its second dual has an identity then that identity must lie inl1(S)
Enhancing COVID-19 public health communication for culturally and linguistically diverse communities: An Australian interview study with community representatives
Background: Public health crises present challenges for providing accessible, timely, and accurate health information to culturally and linguistically diverse (CALD) communities. Aim: The aim of this qualitative project was to explore strategies used by CALD community organizations to improve communication about COVID-19 for their communities; we also aimed to identify gaps and challenges. Methods: We interviewed 16 representatives from Greek, Italian, and Chinese CALD organizations in Melbourne, Australia. The interviews were analyzed thematically. Results: Community leaders played a significant role in engaging their community members with accurate key health information. There were differences between language communities about preferred channels for receiving information. As the pandemic intensified, there was a shift from written communication to more interactive exchanges between authorities and community leaders. Discussion: The findings suggest effective public health communication is enhanced by the mediation and outreach strategies adopted by CALD community organizations; further, stakeholders need to be cognizant of heterogeneity of needs and preferences. This may optimize information dissemination to meet specific needs. Conclusions:The CALD organizations have developed communication strategies involving different kinds of mediation to reach specific sub-groups, especially the most vulnerable. These strategies can inform future public health engagement
N-Acetyltransferase 2 Genotypes among Zulu-Speaking South Africans and Isoniazid and N-Acetyl-Isoniazid Pharmacokinetics during Antituberculosis Treatment.
The distribution of N-acetyltransferase 2 gene (NAT2) polymorphisms varies considerably among different ethnic groups. Information on NAT2 single-nucleotide polymorphisms in the South African population is limited. We investigated NAT2 polymorphisms and their effect on isoniazid pharmacokinetics (PK) in Zulu black HIV-infected South Africans in Durban, South Africa. HIV-infected participants with culture-confirmed pulmonary tuberculosis (TB) were enrolled from two unrelated studies. Participants with culture-confirmed pulmonary TB were genotyped for the NAT2 polymorphisms 282C>T, 341T>C, 481C>T, 857G>A, 590G>A, and 803A>G using Life Technologies prevalidated TaqMan assays (Life Technologies, Paisley, UK). Participants underwent sampling for determination of plasma isoniazid and N-acetyl-isoniazid concentrations. Among the 120 patients, 63/120 (52.5%) were slow metabolizers (NAT2*5/*5), 43/120 (35.8%) had an intermediate metabolism genotype (NAT2*5/12), and 12/120 (11.7%) had a rapid metabolism genotype (NAT2*4/*11, NAT2*11/12, and NAT2*12/12). The NAT2 alleles evaluated in this study were *4, *5C, *5D, *5E, *5J, *5K, *5KA, *5T, *11A, *12A/12C, and *12M. NAT2*5 was the most frequent allele (70.4%), followed by NAT2*12 (27.9%). Fifty-eight of 60 participants in study 1 had PK results. The median area under the concentration-time curve from 0 to infinity (AUC0-â) was 5.53 (interquartile range [IQR], 3.63 to 9.12 ÎŒg h/ml), and the maximum concentration (Cmax) was 1.47 ÎŒg/ml (IQR, 1.14 to 1.89 ÎŒg/ml). Thirty-four of 40 participants in study 2 had both PK results and NAT2 genotyping results. The median AUC0-â was 10.76 ÎŒg·h/ml (IQR, 8.24 to 28.96 ÎŒg·h/ml), and the Cmax was 3.14âÎŒg/ml (IQR, 2.39 to 4.34 ÎŒg/ml). Individual polymorphisms were not equally distributed, with some being represented in small numbers. The genotype did not correlate with the phenotype, with those with a rapid acetylator genotype showing higher AUC0-â values than those with a slow acetylator genotype, but the difference was not significant (Pâ=â0.43). There was a high prevalence of slow acetylator genotypes, followed by intermediate and then rapid acetylator genotypes. The poor concordance between genotype and phenotype suggests that other factors or genetic loci influence isoniazid metabolism, and these warrant further investigation in this population
Point of care Xpert MTB/RIF versus smear microscopy for tuberculosis diagnosis in southern African primary care clinics : a multicentre economic evaluation
CITATION: Pooran, A., et al. 2019. Point of care Xpert MTB/RIF versus smear microscopy for tuberculosis diagnosis in southern African primary care clinics : a multicentre economic evaluation. The Lancet Global Health, 7(6):E798-E807. doi:10.1016/S2214-109X(19)30164-0The original publication is available at https://www.thelancet.com/journals/langlo/homeBackground: Rapid on-site diagnosis facilitates tuberculosis control. Performing Xpert MTB/RIF (Xpert) at point of care is feasible, even when performed by minimally trained health-care workers, and when compared with point-of-care smear microscopy, reduces time to diagnosis and pretreatment loss to follow-up. However, whether Xpert is cost-effective at point of care remains unclear.
Methods: We empirically collected cost (US23·00 [95% CI 22·12â23·88] vs 35â529 (27â054â40â025) and was associated with an additional 24·3 treatment initiations ([â20·0 to 68·5]; 511 per same-day treatment), and 29·4 treatment completions ([â6·9 to 65·6]; 3820 per treatment completion.
Interpretation: In southern Africa, although point-of-care Xpert unit cost is higher than Lab Xpert, it is likely to offer good value for money relative to smear microscopy. With the current availability of point-of-care nucleic acid amplification platforms (eg, Xpert Edge), these data inform much needed investment and resource allocation strategies in tuberculosis endemic settings.https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(19)30164-0/fulltextPublisherâs versio
Determinants of Multidrug-Resistant Tuberculosis Clusters, California, USA, 2004â2007
TOC summary: Type of isoniazid resistanceâconferring mutation may be a determinant of genotypic clustering
Global patterns in genomic diversity underpinning the evolution of insecticide resistance in the aphid crop pest Myzus persicae
Abstract: The aphid Myzus persicae is a destructive agricultural pest that displays an exceptional ability to develop resistance to both natural and synthetic insecticides. To investigate the evolution of resistance in this species we generated a chromosome-scale genome assembly and living panel of >110 fully sequenced globally sampled clonal lines. Our analyses reveal a remarkable diversity of resistance mutations segregating in global populations of M. persicae. We show that the emergence and spread of these mechanisms is influenced by hostâplant associations, uncovering the widespread coâoption of a host-plant adaptation that also offers resistance against synthetic insecticides. We identify both the repeated evolution of independent resistance mutations at the same locus, and multiple instances of the evolution of novel resistance mechanisms against key insecticides. Our findings provide fundamental insights into the genomic responses of global insect populations to strong selective forces, and hold practical relevance for the control of pests and parasites.Peer reviewedFinal Published versio
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