793 research outputs found

    Measuring the Cosmological Geometry from the Lyman Alpha Forest along Parallel Lines of Sight

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    We discuss the feasibility of measuring the cosmological metric using the redshift space correlation function of the Lya forest in multiple lines of sight, as a function of angular and velocity separation. The geometric parameter that is measured is f(z) = H(z) D(z)/c, where H(z) is the Hubble constant and D(z) the angular diameter distance at redshift z. The correlation function is computed in linear theory. We describe a method to measure it from observations with the Gaussianization procedure of Croft et al (1998) to map the Lya forest transmitted flux to an approximation of the linear density field. The effect of peculiar velocities on the shape of the recovered power spectrum is pointed out. We estimate the error in recovering the f(z) factor from observations due to the variance in the Lya absorbers. We show that ~ 20 pairs of quasars (separations < 3') are needed to distinguish a flat \Omega_0=1 universe from a universe with \Omega_0=0.2, \Omega_\Lambda=0.8. A second parameter that is obtained from the correlation function of the Lya forest is \beta \simeq \Omega(z)^{0.6}/b (affecting the magnitude of the peculiar velocities), where b is a linear theory bias of the Lya forest. The statistical error of f(z) is reduced if b can be determined independently from numerical simulations, reducing the number of quasar pairs needed for constraining cosmology to approximately six. On small scales, where the correlation function is higher, f(z) should be measurable with fewer quasars, but non-linear effects must then be taken into account. The anisotropy of the non-linear redshift space correlation function as a function of scale should also provide a precise quantitative test of the gravitational instability theory of the Lya forest.Comment: submitted to Ap

    The Gravitational Lensing in Redshift-space Correlation Functions of Galaxies and Quasars

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    The gravitational lensing, as well as the velocity field and the cosmological light-cone warp, changes the observed correlation function of high-redshift objects. We present an analytical expression of 3D correlation function, simultaneously including those three effects. When two objects are separated over several hundreds Mpc along a line of sight, the observed correlation function is dominated by the effect of gravitational lensing rather than the intrinsic clustering. For a canonical lambda-CDM model, the lensing signals in the galaxy-galaxy and galaxy-QSO correlations are beyond noise levels in large-scale redshift surveys like the Sloan Digital Sky Survey.Comment: 10 pages, 1 figure, submitted to ApJ

    Farmer-Driven Research for Developing Models of Successful Low Input Dairy Farms of Small to Medium Size in the American Midwest

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    The dairy industry in the upper Midwest continues to evolve with a drastic reduction in the number of dairy farms with less than 100 cows that utilise tie-stall housing. Many of the farms that do remain are at a critical point where facilities require renovation or replacement that is not economic. Rural communities have fewer residents engaged in agriculture to participate in the local economy and the rural landscape includes many farm sites that are abandoned. Low input dairies are an alternative system developed by farmers as a grass-roots movement. Low input farms may include grazing, outdoor housing throughout the year, crossbreeding, group housing of calves, etc. Barns formerly used to stable cows may be renovated to provide a milking centre. Low input dairy farmers are eager to participate in on-farm research when they determine the direction of research. We will describe one trial designed to answer questions determined by farmers and outline our research approach to designing effective reduced input dairy farms. The objective is to identify the essential components of management and organisation for low input dairy farms in the American Midwest

    Cardiac function and myocardial perfusion immediately following maximal treadmill exercise inside the MRI room

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    Treadmill exercise stress testing is an essential tool in the prevention, detection, and treatment of a broad spectrum of cardiovascular disease. After maximal exercise, cardiac images at peak stress are typically acquired using nuclear scintigraphy or echocardiography, both of which have inherent limitations. Although CMR offers superior image quality, the lack of MRI-compatible exercise and monitoring equipment has prevented the realization of treadmill exercise CMR

    Prospects for Determining the Equation of State of the Dark Energy: What can be Learned from Multiple Observables?

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    The dark energy that appears to produce the accelerating expansion of the universe can be characterized by an equation of state p=w\rho with w<-1/3. A number of observational tests have been proposed to study the value or redshift dependence of w, including SN Ia distances, the Sunyaev-Zel'dovich effect, cluster abundances, strong and weak gravitational lensing, galaxy and quasar clustering, galaxy ages, the \lya forest, and CMB anisotropies. The proposed observational tests based on these phenomena measure either the distance-redshift relation d(z), the Hubble parameter H(z), the age of the universe t(z), the linear growth factor D_1(z), or some combination of these quantities. We compute the evolution of these four observables, and of the combination H(z)d(z) that enters the Alcock-Paczyznski anisotropy test, in models with constant w, in quintessence models with some simple forms of the potential V(\phi), and in toy models that allow more radical time variations of w. Measurement of any of these quantities to precision of a few percent is generally sufficient to discriminate between w=-1 and w=-2/3. However, the time-dependence predicted in quintessence models is extremely difficult to discern because the quintessence component is dynamically unimportant at the redshifts where w departs substantially from its low-z value. Even for the toy models that allow substantial changes in w at low redshift, there is always a constant-w model that produces very similar evolution of all of the observables simultaneously. We conclude that measurement of the effective equation of state of the dark energy may be achieved by several independent routes in the next few years, but that detecting time-variation in this equation of state will prove very difficult except in specialized cases.Comment: 29 pages, 7 figures, many minor corrections, additions, and clarifications, to appear in Ap

    Minicomputer Capabilities Related to Meteorological Aspects of Emergency Response

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    The purpose of this report is to provide the NRC staff involved in reviewing licensee emergency response plans with background information on the capabilities of minicomputer systems that are related to the collection and dissemination of meteorological infonmation. The treatment of meteorological information by organizations with existing emergency response capabilities is described, and the capabilities, reliability and availability of minicomputers and minicomputer systems are discussed

    Factors associated with alcohol reduction in harmful and hazardous drinkers following alcohol brief intervention in Scotland: a qualitative enquiry

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    Background: Alcohol Brief Intervention (ABI) uses a motivational counselling approach to support individuals to reduce excessive alcohol consumption. There is growing evidence on ABI’s use within various health care settings, although how they work and which components enhance success is largely unknown. This paper reports on the qualitative part of a mixed methods study. It explores enablers and barriers associated with alcohol reduction following an ABI. It focuses on alcohol’s place within participants’ lives and their personal perspectives on reducing consumption. There are a number of randomised controlled trials in this field though few ABI studies have addressed the experiences of hazardous/harmful drinkers. This study examines factors associated with alcohol reduction in harmful/hazardous drinkers following ABI. Methods: This qualitative study was underpinned by a realist evaluation approach and involved semistructured interviews with ten harmful or hazardous alcohol drinkers. Participants (n = 10) were from the intervention arm of a randomised controlled trial (n = 124). All had received ABI, a 20 min motivational counselling interview, six months previously, and had reduced their alcohol consumption. Interviews were recorded, transcribed verbatim and thematically analysed. Results: Participants described their views on alcohol, its’ place in their lives, their personal perspectives on reducing their consumption and future aspirations. Conclusions: The findings provide an insight into participants’ views on alcohol, ABI, and the barriers and enablers to change. Participants described a cost benefit analysis, with some conscious consideration of the advantages and disadvantages of reducing intake or abstaining from alcohol. Findings suggest that, whilst hospital admission can act as a catalyst, encouraging individuals to reflect on their alcohol consumption through ABI may consolidate this, turning this reflective moment into action. Sustainability may be enhanced by the presence of a ‘significant other’ who encourages and experiences benefit. In addition having a purpose or structure with activities linked to employment and/or social and leisure pursuits offers the potential to enhance and sustain reduced alcohol consumption. Trial registration: Trial registration number TRN NCT00982306 September 22nd 200

    A multicentre, randomised controlled trial of PDSAFE, a physiotherapist-delivered fall prevention programme for people with Parkinson’s

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    This is the author accepted manuscript. The final version is available from BMJ Publishing Group via the DOI in this record.Objective: To estimate the effect of a physiotherapist-delivered fall-prevention programme for people with Parkinson’s (PwP). Methods: People at risk of falls with confirmed Parkinson’s were recruited to this multi-centre, pragmatic, investigator blind, individually randomised controlled trial with pre-specified sub-group analyses. 474 PwP (Hoehn and Yahr 1-4) were randomised: 238 allocated to a physiotherapy programme and 236 to control. All participants had routine care; the control group received a DVD about Parkinson’s and single advice session at trial completion. The intervention group (PDSAFE) had an individually tailored, progressive home-based fall-avoidance strategy training programme with balance and strengthening exercises. The primary outcome was risk of repeat-falling, collected by self-report monthly diaries, 0 to 6 months post-randomisation. Secondary outcomes included, Mini-BESTest for balance, chair stand test, Falls Efficacy, freezing of gait, health related quality of life (Euroqol EQ-5D), Geriatric Depression Scale, Physical Activity Scale for the Elderly and Parkinson’s disease Questionnaire, fractures and rate of near-falling. Results: Average age, 72 years and 266 (56%) were men. By 6 months 116 (55%) of the control group, and 125 (61.5%) of the intervention group reported repeat falls (controlled odds ratio 1.21, 95% confidence interval 0.74 to 1.98, P=0.447). Secondary sub-group analyses suggested a different response to the intervention between moderate and severe disease severity groups. Balance, falls efficacy and chair stand time improved with near-falls reduced in the intervention arm. Conclusion: PDSAFE did not reduce falling in this pragmatic trial of PwP. Other functional tasks improved and reduced fall rates were apparent among those with moderate disease.Department of HealthNational Institute for Health Research (NIHR

    2022 taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales

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    In March 2022, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by two new families (bunyaviral Discoviridae and Tulasviridae), 41 new genera, and 98 new species. Three hundred forty-nine species were renamed and/or moved. The accidentally misspelled names of seven species were corrected. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.Instituto de PatologĂ­a VegetalFil: Kuhn, Jens H. National Institute of Allergy and Infectious Diseases. National Institutes of Health. Integrated Research Facility at Fort Detrick; Estados UnidosFil: Adkins, Scott. US Horticultural Research Laboratory. United States Department of Agriculture. Agricultural Research Service; Estados UnidosFil: Alkhovsky, Sergey V. Ministry of Health of Russian Federation. National Center on Epidemiology and Microbiology .D.I. Ivanovsky Institute of Virology of N.F. Gamaleya; RusiaFil: AvĆĄič-Ćœupanc, Tatjana. University of Ljubljana. Faculty of Medicine. Institute of Microbiology and Immunology; EsloveniaFil: AyllĂłn, MarĂ­a A. Universidad PolitĂ©cnica de Madrid. Instituto Nacional de InvestigaciĂłn y TecnologĂ­a Agraria y Alimentaria.Centro de BiotecnologĂ­a y GenĂłmica de Plantas; EspañaFil: AyllĂłn, MarĂ­a A. Universidad PolitĂ©cnica de Madrid. Escuela TĂ©cnica Superior de IngenierĂ­a AgronĂłmica, Alimentaria y de Biosistemas. Departamento de BiotecnologĂ­a-BiologĂ­a Vegetal; EspañaFil: Bahl, Justin. University of Georgia. Center for Ecology of Infectious Diseases. Insitute of Bioinformatics. Department of Infectious Diseases. Department of Epidemiology and Biostatistics; Estados UnidosFil: Balkema-Buschmann, Anne. Friedrich-Loeffler-Institut. Institute of Novel and Emerging Infectious Diseases; AlemaniaFil: Ballinger, Matthew J. Mississippi State University. Department of Biological Sciences; Estados UnidosFil: Bandte, Martina. Humboldt-UniversitĂ€t zu Berlin. Faculty of Life Sciences. Division Phytomedicine; AlemaniaFil: Beer, Martin. Friedrich-Loeffler-Institut. Institute of Diagnostic Virology; AlemaniaFil: Bejerman, Nicolas Esteban. Instituto Nacional de TecnologĂ­a Agropecuaria (INTA). Instituto de PatologĂ­a Vegetal; ArgentinaFil: Bejerman, Nicolas Esteban. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Unidad de FitopatologĂ­a y ModelizaciĂłn AgrĂ­cola (UFyMA); ArgentinaFil: Lodden Økland, Arnfnn. Pharmaq Analytiq; Norueg

    Spatiotemporal Analysis of the January Northern Hemisphere Circumpolar Vortex Over the Contiguous United States

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    January 2014 will be remembered for the sensationalized media usage of the term polar vortex which coincided with several polar air outbreaks. A United States polar vortex (USPV) perspective is presented to better understand the January spatial and temporal variability of this regional component of the Northern Hemisphere circumpolar vortex. Use of the monthly mean 5460 m isohypse to represent the location of the USPV extent and area revealed that the spatial features of the January 2014 USPV were not extreme relative to certain 1948–2013 Januaries. Furthermore, the Arctic Oscillation (AO), Pacific-North American (PNA) Pattern, and Pacific Decadal Oscillation (PDO) are all linked to southernmost latitude of the USPV trough, but the PDO and PNA are most closely associated with the longitude at which this latitude occurs. The AO is closely related to the area of the United States enclosed within the USPV
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