1,023 research outputs found
MEASURING THE RETURNS TO AGRICULTURAL EXPERIMENT STATION RESEARCH EXPENDITURES FOR CORN, WHEAT AND SOYBEANS
Research and Development/Tech Change/Emerging Technologies,
The short-period limit of contact binaries
The stability of mass transfer is important in the formation of contact
binaries from detached binaries when the primaries of the initially detached
binaries fill their Roche lobes. Using Eggleton's stellar evolution code, we
investigate the formation and the short-period limit of contact binaries by
considering the effect of the instability of mass transfer. It is found that
with decreasing initial primary mass from 0.89M to 0.63M, the range of the initial mass ratio decreases for detached binaries
that experience stable mass transfer and evolve into contact. If the initial
primary mass is less than 0.63M, detached binaries would
experience dynamically unstable mass transfer when the primaries of detached
binaries fill their Roche lobes. These systems would evolve into a common
envelope situation and probably then to a complete merger of two components on
a quite short timescale. This results in a low mass limit at about 0.63M for the primary mass of contact binaries, which might be a main reason
why the period distribution of contact binaries has a short limit of about 0.22
days. By comparing the theoretical period distribution of contact binaries with
the observational data, it is found that the observed contact binaries are
above the low mass limit for the primary mass of contact binaries and no
observed contact binaries are below this limit. This suggests that the
short-period limit of contact binaries can be explained by the instability of
the mass transfer that occurs when the primaries of the initially detached
binaries fill their Roche lobes.Comment: 11 pages, 4 figures, Accepted for publication in Monthly Notice
Four ultra-short period eclipsing M-dwarf binaries in the WFCAM Transit Survey
We report on the discovery of four ultra-short period (P<0.18 days) eclipsing
M-dwarf binaries in the WFCAM Transit Survey. Their orbital periods are
significantly shorter than of any other known main-sequence binary system, and
are all significantly below the sharp period cut-off at P~0.22 days as seen in
binaries of earlier type stars. The shortest-period binary consists of two M4
type stars in a P=0.112 day orbit. The binaries are discovered as part of an
extensive search for short-period eclipsing systems in over 260,000 stellar
lightcurves, including over 10,000 M-dwarfs down to J=18 mag, yielding 25
binaries with P<0.23 days. In a popular paradigm, the evolution of short period
binaries of cool main-sequence stars is driven by loss of angular momentum
through magnetised winds. In this scheme, the observed P~0.22 day period
cut-off is explained as being due to timescales that are too long for
lower-mass binaries to decay into tighter orbits. Our discovery of low-mass
binaries with significantly shorter orbits implies that either these timescales
have been overestimated for M-dwarfs, e.g. due to a higher effective magnetic
activity, or that the mechanism for forming these tight M-dwarf binaries is
different from that of earlier type main-sequence stars.Comment: 22 pages, 17 figures, 3 tables Accepted for publication in MNRA
The Effect of Communication Change on Longâterm Reductions in Child Exposure to Conflict: Impact of the Promoting Strong African American Families (ProSAAF) Program
African American couples (n = 331) with children, 89% of whom were married, were assigned to either (a) a culturally sensitive coupleâ and parentingâenhancement program (ProSAAF) or (b) an informationâonly control condition in which couples received selfâhelp materials. Husbands averaged 41 years of age and wives averaged 39 years. We found significant effects of program participation in the short term on couple communication, which was targeted by the intervention, as well as over the long term, on selfâreported arguing in front of children. Longâterm parenting outcomes were fully mediated by changes in communication for wives, but not for husbands. For husbands, positive change depended on amount of wife reported change. We conclude that wives\u27 changes in communication from baseline to posttest may be more pivotal for the couples\u27 longâterm experience of decreased arguing in front of children than are husbands\u27 changes, with wives\u27 changes leading to changes in both partners\u27 reports of arguments in front of children
The 'help' question doesn't help when screening for major depression: external validation of the three-question screening test for primary care patients managed for physical complaints
Major depression, although frequent in primary care, is commonly hidden behind multiple physical complaints that are often the first and only reason for patient consultation. Major depression can be screened by two validated questions that are easier to use in primary care than the full Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria. A third question, called the 'help' question, improves the specificity without apparently decreasing the sensitivity of this screening procedure. We validated the abbreviated screening procedure for major depression with and without the 'help' question in primary care patients managed for a physical complaint.
This diagnostic accuracy study used data from the SODA (for 'SOmatisation Depression Anxiety') cohort study conducted by 24 general practitioners (GPs) in western Switzerland that included patients over 18 years of age with at least a single physical complaint at index consultation. Major depression was identified with the full Patient Health Questionnaire. GPs were asked to screen patients for major depression with the three screening questions 1 year after inclusion.
Of 937 patients with at least a single physical complaint, 751 were eligible 1 year after index consultation. Major depression was diagnosed in 69/724 (9.5%) patients. The sensitivity and specificity of the two-question method alone were 91.3% (95% CI 81.4 to 96.4) and 65.0% (95% CI 61.2 to 68.6), respectively. Adding the 'help' question decreased the sensitivity (59.4%; 95% CI 47.0 to 70.9) but improved the specificity (88.2%; 95% CI 85.4 to 90.5) of the three-question method.
The use of two screening questions for major depression was associated with high sensitivity and low specificity in primary care patients presenting a physical complaint. Adding the 'help' question improved the specificity but clearly decreased the sensitivity; when using the 'help' question, four out of ten patients with depression will be missed, compared to only one out of ten with the two-question method. Therefore, the 'help' question is not useful as a screening question, but may help discussing management strategies
No Sun-like dynamo on the active star ζ Andromedae from starspot asymmetry
This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.Sunspots are cool areas caused by strong surface magnetic fields inhibiting convection. Moreover, strong magnetic fields can alter the average atmospheric structure , degrading our ability to measure stellar masses and ages. Stars more active than the Sun have more and stronger dark spots than in the solar case, including on the rotational pole itself. Doppler imaging, which has so far produced the most detailed images of surface structures on other stars than the Sun, cannot always distinguish the hemisphere in which the starspots are located, especially in the equatorial region and if the data quality is not optimal . This leads to problems in investigating the north-south distribution of starspot active latitudes (those latitudes with more spot activity), which are crucial constraints of dynamo theory. Polar spots, inferred only from Doppler tomography, could plausibly be observational artifacts, casting some doubt on their very existence. Here we report imaging of the old, magnetically-active star ζ Andromedae using long-baseline infrared interferometry. In our data, a dark polar spot is seen in each of two epochs, while lower-latitude spot structures in both hemispheres do not persist between observations revealing global starspot asymmetries. The north-south symmetry of active latitudes observed on the Sun is absent on ζ And, which hosts global spot patterns that cannot be produced by solar-type dynamos.National Science Foundation (NSF)Hungarian Academy of Science
Obstetric professionalsâ perceptions of non-invasive prenatal testing for Down syndrome: clinical usefulness compared with existing tests and ethical implications
Background: While non-invasive prenatal testing (NIPT) for fetal aneuploidy is commercially available in many countries, little is known about how obstetric professionals in non-Western populations perceive the clinical usefulness of NIPT in comparison with existing first-trimester combined screening (FTS) for Down syndrome (DS) or invasive prenatal diagnosis (IPD), or perceptions of their ethical concerns arising from the use of NIPT. Methods: A cross-sectional survey among 327 obstetric professionals (237 midwives, 90 obstetricians) in Hong Kong. Results: Compared to FTS, NIPT was believed to: provide more psychological benefits and enable earlier consideration of termination of pregnancy. Compared to IPD, NIPT was believed to: provide less psychological stress for high-risk women and more psychological assurance for low-risk women, and offer an advantage to detect chromosomal abnormalities earlier. Significant differences in perceived clinical usefulness were found by profession and healthcare sector: (1) obstetricians reported more certain views towards the usefulness of NIPT than midwives and (2) professionals in the public sector perceived less usefulness of NIPT than the private sector. Beliefs about earlier detection of DS using NIPT were associated with ethical concerns about increasing abortion. Participants believing that NIPT provided psychological assurance among low-risk women were less likely to be concerned about ethical issues relating to informed decision-making and pre-test consultation for NIPT. Conclusions: Our findings suggest the need for political debate initially on how to ensure pregnant women accessing public services are informed about commercially available more advanced technology, but also on the potential implementation of NIPT within public services to improve access and equity to DS screening services
MicroRNA degradation by a conserved target RNA regulates animal behavior
International audiencemicroRNAs (miRNAs) repress target transcripts through partial complementarity. By contrast, highly complementary miRNA-binding sites within viral and artificially engineered transcripts induce miRNA degradation in vitro and in cell lines. Here, we show that a genome-encoded transcript harboring a near-perfect and deeply conserved miRNA-binding site for miR-29 controls zebrafish and mouse behavior. This transcript originated in basal vertebrates as a long noncoding RNA (lncRNA) and evolved to the protein-coding gene NREP in mammals, where the miR-29-binding site is located within the 3âČ UTR. We show that the near-perfect miRNA site selectively triggers miR-29b destabilization through 3âČ trimming and restricts its spatial expression in the cerebellum. Genetic disruption of the miR-29 site within mouse Nrep results in ectopic expression of cerebellar miR-29b and impaired coordination and motor learning. Thus, we demonstrate an endogenous target-RNA-directed miRNA degradation event and its requirement for animal behavio
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets
containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass
energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The
measurements use data corresponding to an integrated luminosity of 34 pb^-1.
The b-jets are identified using either a lifetime-based method, where secondary
decay vertices of b-hadrons in jets are reconstructed using information from
the tracking detectors, or a muon-based method where the presence of a muon is
used to identify semileptonic decays of b-hadrons inside jets. The inclusive
b-jet cross-section is measured as a function of transverse momentum in the
range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet
cross-section is measured as a function of the dijet invariant mass in the
range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets
and the angular variable chi in two dijet mass regions. The results are
compared with next-to-leading-order QCD predictions. Good agreement is observed
between the measured cross-sections and the predictions obtained using POWHEG +
Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet
cross-section. However, it does not reproduce the measured inclusive
cross-section well, particularly for central b-jets with large transverse
momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final
version published in European Physical Journal
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