1,423 research outputs found

    The Peculiar Velocities of Local Type Ia Supernovae and their Impact on Cosmology

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    We quantify the effect of supernova Type Ia peculiar velocities on the derivation of cosmological parameters. The published distant and local Ia SNe used for the Supernova Legacy Survey first-year cosmology report form the sample for this study. While previous work has assumed that the local SNe are at rest in the CMB frame (the No Flow assumption), we test this assumption by applying peculiar velocity corrections to the local SNe using three different flow models. The models are based on the IRAS PSCz galaxy redshift survey, have varying beta = Omega_m^0.6/b, and reproduce the Local Group motion in the CMB frame. These datasets are then fit for w, Omega_m, and Omega_Lambda using flatness or LambdaCDM and a BAO prior. The chi^2 statistic is used to examine the effect of the velocity corrections on the quality of the fits. The most favored model is the beta=0.5 model, which produces a fit significantly better than the No Flow assumption, consistent with previous peculiar velocity studies. By comparing the No Flow assumption with the favored models we derive the largest potential systematic error in w caused by ignoring peculiar velocities to be Delta w = +0.04. For Omega_Lambda, the potential error is Delta Omega_Lambda = -0.04 and for Omega_m, the potential error is Delta Omega_m < +0.01. The favored flow model (beta=0.5) produces the following cosmological parameters: w = -1.08 (+0.09,-0.08), Omega_m = 0.27 (+0.02,-0.02) assuming a flat cosmology, and Omega_Lambda = 0.80 (+0.08,-0.07) and Omega_m = 0.27 (+0.02,-0.02) for a w = -1 (LambdaCDM) cosmology.Comment: 4 pages, 2 figures, 1 table, accepted for publication in ApJ Letter

    Advanced prosthodontic training in the United States of America

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    AbstractThis article will consider prosthodontic specialty training in the United States.The history of prosthodontics as a specialty and the requirements necessary to be considered a prosthodontist will be explored. Today, a three-year postgraduate program is necessary to be considered an educationally qualified prosthodontist. Currently, there are 46 accredited advanced specialty education programs in the United States and approximately 3200 prosthodontists. The standards and training required for completion of these programs will be considered

    Child Abuse in a Small City: Social Psychological and Ecological Correlates

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    Child abuse has become a growing national concern. Its current status can be linked to the research by Kempe who identified the battered child syndrome . Two models of explanation have been advanced; a medical and a social psychological. This study of 134 cases of child abuse in a small city employes the social psychological model and tests the hypothesis that social isolation is correlated with child abuse. Support for that hypothesis leads to an elaboration of the dynamics of social isolation with an emphasis on the absence of other persons with children from the milieu of the child abuse perpetrator and the consequence of having little knowledge about parenting. The incidents were also found not to be randomly distributed in the community. The characteristics of these areas are examined

    Movement Patterns of Large Brown Trout in the Mainstream Au Sable River, Michigan

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    We used radiotelemetry to monitor spring and summer movements of 11 brown trout Salmo trutta (442–584 mm) for up to 904 d in a Michigan stream. Individual brown trout used a few specific locations near cover (referred to as home sites) as resting locations during the day, moved across various distances at night, and generally returned to the same home site the next morning. Home sites were predominantly artificial cover (88%) rather than natural sites, as natural cover was very limited in the study area. Some fish used multiple home sites, and the average separation between multiple home sites for individual fish was over 500 m. Fish tracked for more than 1 year used the same home sites each summer and generally exhibited similar behavior each year. Fish belonged to two general categories of daily movement behavior: mobile or stationary. Mobile fish tended to move frequently and were found within their home sites only 43% of the time at night. Stationary fish did not move far from home sites, even at night. There was a negative correlation between the average gradient and the maximum distance fish moved from their home sites during nocturnal periods. Stationary fish resided in areas of steeper gradient (usually about 0.20%) and moved less often nocturnally than did mobile fish. Three fish were tracked extensively over 36 d to quantify diel activity patterns. The hourly activity of fish increased dramatically at dusk, continued at a lower level overnight, and then increased again at dawn before declining to near zero during the day. This behavior pattern was similar among all individuals tracked and also between the months of June, July, and August for an individual fish. Nocturnal movements involved significantly greater distances than diurnal movements for these fish. The relationship between movement and gradient may indicate energetic tradeoffs between the cost of moving against a current and the energy gained during active foraging. Also, the dominant use of artificial home sites has implications for the value of habitat improvements meant to increase abundance of large brown trout.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141462/1/tafs0034.pd

    Simple Synchronous Detector for Spectroscopic Studies

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    Lock-in-amplifiers are used in many applications for signal processing and offer the ability to discriminate high levels of noise. While these instruments are very powerful and offer many features, they are not portable and are expensive. An economical and easy to use alternative circuit is presented which incorporates pre-amplification, reference, and synchronous detection on one circuit board. The design can be used in laboratory or process control situations where its small size and low cost are advantageous. The circuit was successfully applied to moderate and high level signals as seen in flame infrared emission detection and in a portable radiometer for rocket plume studies

    Estimating the Prevalence of Disease Using Relatives of Case and Control Probands

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    We introduce a method for estimating the prevalence of disease using data from a case-control family study performed to investigate the aggregation of disease in families. The families are sampled via case and control probands, and the resulting data consist of information on disease status and covariates for the probands and their relatives. We introduce estimators for overall prevalence and for covariate stratum-specific prevalence (e.g., sex-specific prevalence) that yield approximately unbiased estimates of their population counterparts. We also introduce corresponding confidence intervals that have good coverage properties even for small prevalences. The estimators and intervals address the over-representation of diseased individuals in case-control family data by using only the relatives (of the probands) and by taking into account whether each relative was selected via a case or a control proband. Finally, we describe a simulation experiment in which the estimators and intervals were applied to case-control family datasets sampled from a fictional population that resembled the catchment area for an Austrian family study of major depressive disorder. The resulting estimates varied closely and symmetrically around their population counterparts, and the resulting intervals had good coverage properties

    Do ecosystem service maps and models meet stakeholders’ needs? A preliminary survey across sub-Saharan Africa

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    To achieve sustainability goals, it is important to incorporate ecosystem service (ES) information into decision-making processes. However, little is known about the correspondence between the needs of ES information users and the data provided by the researcher community. We surveyed stakeholders within sub-Saharan Africa, determining their ES data requirements using a targeted sampling strategy. Of those respondents utilising ES information (>90%; n=60), 27% report having sufficient data; with the remainder requiring additional data – particularly at higher spatial resolutions and at multiple points in time. The majority of respondents focus on provisioning and regulating services, particularly food and fresh water supply (both 58%) and climate regulation (49%). Their focus is generally at national scales or below and in accordance with data availability. Among the stakeholders surveyed, we performed a follow-up assessment for a sub-sample of 17 technical experts. The technical experts are unanimous that ES models must be able to incorporate scenarios, and most agree that ES models should be at least 90% accurate. However, relatively coarse-resolution (1–10 km2) models are sufficient for many services. To maximise the impact of future research, dynamic, multi-scale datasets on ES must be delivered alongside capacity-building efforts

    Dairy herd mastitis and reproduction: using simulation to aid interpretation of results from discrete time survival analysis

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    Probabilistic sensitivity analysis (PSA) is a simulation-based technique for evaluating the relative importance of different inputs to a complex process model. It is commonly employed in decision analysis and for evaluation of the potential impact of uncertainty in research findings on clinical practice, but has a wide variety of other possible applications. In this example, it was used to evaluate the association between herd-level udder health and reproductive performance in dairy herds. Although several recent studies have found relatively large associations between mastitis and fertility at the level of individual inseminations or lactations, the current study demonstrated that herd-level intramammary infection status is highly unlikely to have a clinically significant impact on the overall reproductive performance of a dairy herd under typical conditions. For example, a large increase in incidence rate of clinical mastitis (from 92 to 131 cases per 100 cows per year) would be expected to increase a herd's modified FERTEX score (a cost-based measure of overall reproductive performance) by just £4.501 per cow per year. The herd's background level of submission rate (proportion of eligible cows served every 21 days) and pregnancy risk (proportion of inseminations leading to a pregnancy) correlated strongly with overall reproductive performance and explained a large proportion of the between-herd variation in performance. PSA proved to be a highly useful technique to aid understanding of results from a complex statistical model, and has great potential for a wide variety of applications within the field of veterinary science
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