43,163 research outputs found
Are Stars with Planets Polluted?
We compare the metallicities of stars with radial velocity planets to the
metallicity of a sample of field dwarfs. We confirm recent work indicating that
the stars-with-planet sample as a whole is iron rich. However, the lowest mass
stars tend to be iron poor, with several having [Fe/H]<-0.2, demonstrating that
high metallicity is not required for the formation of short period Jupiter-mass
planets. We show that the average [Fe/H] increases with increasing stellar mass
(for masses below 1.25 solar masses) in both samples, but that the increase is
much more rapid in the stars-with-planet sample. The variation of metallicity
with stellar age also differs between the two samples. We examine possible
selection effects related to variations in the sensitivity of radial velocity
surveys with stellar mass and metallicity, and identify a color cutoff
(B-V>0.48) that contributes to but does not explain the mass-metallicity trend
in the stars-with-planets sample. We use Monte Carlo models to show that adding
an average of 6.5 Earth masses of iron to each star can explain both the
mass-metallicity and the age-metallicity relations of the stars-with-planets
sample. However, for at least one star, HD 38529, there is good evidence that
the bulk metallicity is high. We conclude that the observed metallicities and
metallicity trends are the result of the interaction of three effects;
accretion of about 6 Earth masses of iron rich material, selection effects, and
in some cases, high intrinsic metallicity.Comment: 19 pages 11 figure
Letting Go of Self: The Creation of the Nonattachment to Self Scale
The Buddhist notion of nonattachment relates to an engagement with experience with flexibility and without fixation on achieving specified outcomes. The present study sought to define, create and validate a new measure of nonattachment as it applies to notions of the self. A new construct of “nonattachment to self” (NTS) was developed, defined the absence of fixation on self-related concepts, thoughts and feelings, and a capacity to flexibly interact with these concepts, thoughts and feelings without trying to control them. Two studies were conducted in the development of the new scale. With expert consultation, study 1 (n = 445) established a single factor, internally consistent 7-item scale via exploratory factor analysis. Study 2 (n = 388, n = 338) confirmed the factor structure of the new 7-item scale using confirmatory factor analyses. Study 2 also found the new scale to be internally consistent, with evidence supporting its test-retest reliability, criterion, and construct validity. Nonattachment to self-emerged as a unique way of relating to the self, distinct from general nonattachment, that aligned with higher levels of well-being and adaptive functioning
The bar PANDA focussing-lightguide disc DIRC
bar PANDA will be a fixed target experiment internal to the HESR antiproton storage ring at the future FAIR complex. The ANDA detector requires excellent particle-identification capabilities in order to achieve its scientific potential. Cherenkov counters employing the DIRC principle were chosen as PID detectors for the Target Spectrometer. The proposed Focussing-Lightguide Disc DIRC will cover the forward part of the Target Spectrometer acceptance in the angular range between 5° and 22°. Its design includes a novel approach to mitigate dispersion effects in the solid radiator of a DIRC counter using optical elements. The dispersion correction will enable the Focussing-Lightguide Disc DIRC to provide pion-kaon identification for momenta well above 3.5 GeV/c
Kentucky Bluegrass Floral Induction and Cultivar Response to Mechanical Removal of Harvest Residue
Open-field burning of post-harvest residue from Kentucky bluegrass (Poa pratensis L.) seed fields is being phased out in Washington, USA and may be banned in Idaho. Burning encourages early fall regrowth and timely completion of fall floral induction. Cultivars have different floral induction requirements and respond differently to mechanical residue removal. Our objective was to determine if length of fall floral induction requirement was related to seed yield when post-harvest residue was removed by crewcut vacuum sweeping. Floral induction requirements were not related to first-or second-year seed yields. Third-year seed yield of cultivars with long floral induction requirements declined more than third-year seed yields of cultivars with short floral induction requirements. Turf type, aggressive cultivars usually have longer floral induction requirements than non-aggressive cultivars. Exceptions suggest that turf type cultivars with short floral induction requirements can be developed. Cultivar selection will be important for sustained yields with mechanical residue removal
Renormalised four-point coupling constant in the three-dimensional O(N) model with N=0
We simulate self-avoiding walks on a cubic lattice and determine the second
virial coefficient for walks of different lengths. This allows us to determine
the critical value of the renormalized four-point coupling constant in the
three-dimensional N-vector universality class for N=0. We obtain g* =
1.4005(5), where g is normalized so that the three-dimensional
field-theoretical beta-function behaves as \beta(g) = - g + g^2 for small g. As
a byproduct, we also obtain precise estimates of the interpenetration ratio
Psi*, Psi* = 0.24685(11), and of the exponent \nu, \nu = 0.5876(2).Comment: 16 page
Analysis and design of a high tip speed, low noise aircraft fan incorporating swept leading edge rotor and stator blades
Optimization study of high power static inverters and converters Final report
Optimization study and basic performance characteristics for conceptual designs for high power static inverter
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