51 research outputs found
Dynamical Formation of Millisecond Pulsars in Globular Clusters
The cumulative luminosity distribution functions (CLFs) of radio millisecond
pulsars (MSPs) in globular clusters (GCs) and in the Galactic field at a
frequency of 1.4 GHz have been examined. Assuming a functional form, where is the number of MSPs and is the luminosity at 1.4 GHz, it
is found that the CLFs significantly differ with a steeper slope, , in GCs than in the Galactic field (), suggesting a
different formation or evolutionary history of MSPs in these two regions of the
Galaxy. To probe the production mechanism of MSPs in clusters, a search of the
possible relationships between the MSP population and cluster properties was
carried out. The results of an investigation of 9 GCs indicate positive
correlations between the MSP population and the stellar encounter rate and
metallicity. This provides additional evidence suggesting that stellar
dynamical interactions are important in the formation of the MSP population in
GCs.Comment: 18 pages, 3 figures, 4 tables, accepted for publication in Ap
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Potato varieties : an introduction to variety characteristics, management and performance in the Klamath Basin
Published April 1990. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo
Do multiple outcome measures require p-value adjustment?
BACKGROUND: Readers may question the interpretation of findings in clinical trials when multiple outcome measures are used without adjustment of the p-value. This question arises because of the increased risk of Type I errors (findings of false "significance") when multiple simultaneous hypotheses are tested at set p-values. The primary aim of this study was to estimate the need to make appropriate p-value adjustments in clinical trials to compensate for a possible increased risk in committing Type I errors when multiple outcome measures are used. DISCUSSION: The classicists believe that the chance of finding at least one test statistically significant due to chance and incorrectly declaring a difference increases as the number of comparisons increases. The rationalists have the following objections to that theory: 1) P-value adjustments are calculated based on how many tests are to be considered, and that number has been defined arbitrarily and variably; 2) P-value adjustments reduce the chance of making type I errors, but they increase the chance of making type II errors or needing to increase the sample size. SUMMARY: Readers should balance a study's statistical significance with the magnitude of effect, the quality of the study and with findings from other studies. Researchers facing multiple outcome measures might want to either select a primary outcome measure or use a global assessment measure, rather than adjusting the p-value
The Occurrence of Rocky Habitable-zone Planets around Solar-like Stars from Kepler Data
We present the occurrence rates for rocky planets in the habitable zones (HZs) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define ηâ as the HZ occurrence of planets with radii between 0.5 and 1.5 Râ orbiting stars with effective temperatures between 4800 and 6300 K. We find that ηâ for the conservative HZ is between 0.37^(+0.48)_(â0.21) (errors reflect 68% credible intervals) and 0.60^(+0.90)_(â0.36) planets per star, while the optimistic HZ occurrence is between 0.58^(+0.73)_(â0.33) and 0.88^(+1.28)_(â0.51) planets per star. These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available. The large uncertainties are due to the small number of detected small HZ planets. We find similar occurrence rates between using Poisson likelihood Bayesian analysis and using Approximate Bayesian Computation. Our results are corrected for catalog completeness and reliability. Both completeness and the planet occurrence rate are dependent on stellar effective temperature. We also present occurrence rates for various stellar populations and planet size ranges. We estimate with 95% confidence that, on average, the nearest HZ planet around G and K dwarfs is ~6 pc away and there are ~4 HZ rocky planets around G and K dwarfs within 10 pc of the Sun
The Occurrence of Rocky Habitable Zone Planets Around Solar-Like Stars from Kepler Data
We present occurrence rates for rocky planets in the habitable zones (HZ) of
main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and
Gaia-based stellar properties. We provide the first analysis in terms of
star-dependent instellation flux, which allows us to track HZ planets. We
define as the HZ occurrence of planets with radius between 0.5
and 1.5 orbiting stars with effective temperatures between 4800 K
and 6300 K. We find that for the conservative HZ is between
(errors reflect 68\% credible intervals) and
planets per star, while the optimistic HZ occurrence is
between and planets per star.
These bounds reflect two extreme assumptions about the extrapolation of
completeness beyond orbital periods where DR25 completeness data are available.
The large uncertainties are due to the small number of detected small HZ
planets. We find similar occurrence rates using both a Poisson likelihood
Bayesian analysis and Approximate Bayesian Computation. Our results are
corrected for catalog completeness and reliability. Both completeness and the
planet occurrence rate are dependent on stellar effective temperature. We also
present occurrence rates for various stellar populations and planet size
ranges. We estimate with confidence that, on average, the nearest HZ
planet around G and K dwarfs is about 6 pc away, and there are about 4 HZ rocky
planets around G and K dwarfs within 10 pc of the Sun.Comment: To appear in The Astronomical Journa
Insights from the genome of the biotrophic fungal plant pathogen Ustilago maydis
Ustilago maydis is a ubiquitous pathogen of maize and a well-established model organism for the study of plant-microbe interactions. This basidiomycete fungus does not use aggressive virulence strategies to kill its host. U. maydis belongs to the group of biotrophic parasites (the smuts) that depend on living tissue for proliferation and development. Here we report the genome sequence for a member of this economically important group of biotrophic fungi. The 20.5-million-base U. maydis genome assembly contains 6,902 predicted protein-encoding genes and lacks pathogenicity signatures found in the genomes of aggressive pathogenic fungi, for example a battery of cell-wall-degrading enzymes. However, we detected unexpected genomic features responsible for the pathogenicity of this organism. Specifically, we found 12 clusters of genes encoding small secreted proteins with unknown function. A significant fraction of these genes exists in small gene families. Expression analysis showed that most of the genes contained in these clusters are regulated together and induced in infected tissue. Deletion of individual clusters altered the virulence of U. maydis in five cases, ranging from a complete lack of symptoms to hypervirulence. Despite years of research into the mechanism of pathogenicity in U. maydis, no 'true' virulence factors had been previously identified. Thus, the discovery of the secreted protein gene clusters and the functional demonstration of their decisive role in the infection process illuminate previously unknown mechanisms of pathogenicity operating in biotrophic fungi. Genomic analysis is, similarly, likely to open up new avenues for the discovery of virulence determinants in other pathogens. ©2006 Nature Publishing Group.J.K., M. B. and R.K. thank G. Sawers and U. KĂ€mper for critical reading of the manuscript. The genome sequencing of Ustilago maydis strain 521 is part of the fungal genome initiative and was funded by National Human Genome Research Institute (USA) and BayerCropScience AG (Germany). F.B. was supported by a grant from the National Institutes of Health (USA). J.K. and R.K. thank the German Ministry of Education and Science (BMBF) for financing the DNA array setup and the Max Planck Society for their support of the manual genome annotation. F.B. was supported by a grant from the National Institutes of Health, B.J.S. was supported by the Natural Sciences and Engineering Research Council of Canada and the Canada Foundation for Innovation, J.W.K. received funding from the Natural Sciences and Engineering Research Council of Canada, J.R.-H. received funding from CONACYT, MĂ©xico, A.M.-M. was supported by a fellowship from the Humboldt Foundation, and L.M. was supported by an EU grant. Author Contributions All authors were involved in planning and executing the genome sequencing project. B.W.B., J.G., L.-J.M., E.W.M., D.D., C.M.W., J.B., S.Y., D.B.J., S.C., C.N., E.K., G.F., P.H.S., I.H.-H., M. Vaupel, H.V., T.S., J.M., D.P., C.S., A.G., F.C. and V. Vysotskaia contributed to the three independent sequencing projects; M.M., G.M., U.G., D.H., M.O. and H.-W.M. were responsible for gene model refinement, database design and database maintenance; G.M., J. KĂ€mper, R.K., G.S., M. FeldbrĂŒgge, J.S., C.W.B., U.F., M.B., B.S., B.J.S., M.J.C., E.C.H.H., S.M., F.B., J.W.K., K.J.B., J. Klose, S.E.G., S.J.K., M.H.P., H.A.B.W., R.deV., H.J.D., J.R.-H., C.G.R.-P., L.O.-C., M.McC., K.S., J.P.-M., J.I.I., W.H., P.G., P.S.-A., M. Farman, J.E.S., R.S., J.M.G.-P., J.C.K., W.L. and D.H. were involved in functional annotation and interpretation; T.B., O.M., L.M., A.M.-M., D.G., K.M., N.R., V. Vincon, M. VraneĆ , M.S. and O.L. performed experiments. J. KĂ€mper, R.K. and M.B. wrote and edited the paper with input from L.-J.M., J.G., F.B., J.W.K., B.J.S. and S.E.G. Individual contributions of authors can be found as Supplementary Notes
Physician Global Assessment International Standardisation COnsensus in Systemic Lupus Erythematosus: the PISCOS study
The Physician Global Assessment International Standardisation COnsensus in Systemic Lupus Erythematosus (PISCOS) study aimed to obtain an evidence-based and expert-based consensus standardisation of the Physician Global Assessment (PGA) scoring of disease activity in systemic lupus erythematosus (SLE). An international panel of 79 SLE experts participated in a three-round Delphi consensus process, in which 41 statements related to the PGA in SLE were rated, using a 0 (strongly disagree) to 10 (strongly agree) numerical rating scale. Statements with agreement of 75% or greater were selected and further validated by the expert panel. Consensus was reached on 27 statements, grouped in 14 recommendations, for the use of the PGA in SLE, design of the PGA scale, practical considerations for PGA scoring, and the relationship between PGA values and levels of disease activity. Among these recommendations, the expert panel agreed that the PGA should consist of a 0-3 visual analogue scale for measuring disease activity in patients with SLE in the preceding month. The PGA is intended to rate the overall disease activity, taking into account the severity of active manifestations and clinical laboratory results, but excluding organ damage, serology, and subjective findings unrelated to disease activity. The PGA scale ranges from "no disease activity" (0) to the "most severe disease activity" (3) and incorporates the values 1 and 2 as inner markers to categorise disease activity as mild (>= 0.5 to 1), moderate (>1 and <= 2) and severe (>2 to 3). Only experienced physicians can rate the PGA, and it should be preferably scored by the same rater at each visit. The PISCOS results will allow for increased homogeneity and reliability of PGA ratings in routine clinical practice, definitions of remission and low disease activity, and future SLE trials
AI is a viable alternative to high throughput screening: a 318-target study
: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNetÂź convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNetÂź model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery
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