11,314 research outputs found
HAT-P-30b: A Transiting Hot Jupiter on a Highly Oblique Orbit
We report the discovery of HAT-P-30b, a transiting exoplanet orbiting the V = 10.419 dwarf star GSC 0208-00722. The planet has a period P = 2.810595 ± 0.000005 days, transit epoch Tc = 2455456.46561 ± 0.00037 (BJD), and transit duration 0.0887 ± 0.0015 days. The host star has a mass of 1.24 ± 0.04 M_⊙, radius of 1.21 ± 0.05 R_⊙, effective temperature of 6304 ± 88 K, and metallicity [Fe/H] = +0.13 ± 0.08. The planetary companion has a mass of 0.711 ± 0.028 M J and radius of 1.340 ± 0.065 R J yielding a mean density of 0.37 ± 0.05 g cm^(–3). We also present radial velocity measurements that were obtained throughout a transit that exhibit the Rossiter-McLaughlin effect. By modeling this effect, we measure an angle of λ = 73.°5 ± 9.°0 between the sky projections of the planet's orbit normal and the star's spin axis. HAT-P-30b represents another example of a close-in planet on a highly tilted orbit, and conforms to the previously noted pattern that tilted orbits are more common around stars with T_(eff*) ≳ 6250 K
A large scale prediction of bacteriocin gene blocks suggests a wide functional spectrum for bacteriocins
Bacteriocins are peptide-derived molecules produced by bacteria, whose
recently-discovered functions include virulence factors and signalling
molecules as well as their better known roles as antibiotics. To date, close to
five hundred bacteriocins have been identified and classified. Recent
discoveries have shown that bacteriocins are highly diverse and widely
distributed among bacterial species. Given the heterogeneity of bacteriocin
compounds, many tools struggle with identifying novel bacteriocins due to their
vast sequence and structural diversity. Many bacteriocins undergo
post-translational processing or modifications necessary for the biosynthesis
of the final mature form. Enzymatic modification of bacteriocins as well as
their export is achieved by proteins whose genes are often located in a
discrete gene cluster proximal to the bacteriocin precursor gene, referred to
as \textit{context genes} in this study. Although bacteriocins themselves are
structurally diverse, context genes have been shown to be largely conserved
across unrelated species. Using this knowledge, we set out to identify new
candidates for context genes which may clarify how bacteriocins are
synthesized, and identify new candidates for bacteriocins that bear no sequence
similarity to known toxins. To achieve these goals, we have developed a
software tool, Bacteriocin Operon and gene block Associator (BOA) that can
identify homologous bacteriocin associated gene clusters and predict novel
ones. We discover that several phyla have a strong preference for bactericon
genes, suggesting distinct functions for this group of molecules. Availability:
https://github.com/idoerg/BOAComment: Accepted for publication in BMC Bioinformatic
Stellar and Planetary Properties of K2 Campaign 1 Candidates and Validation of 17 Planets, Including a Planet Receiving Earth-like Insolation
The extended Kepler mission, K2, is now providing photometry of new fields
every three months in a search for transiting planets. In a recent study,
Foreman-Mackey and collaborators presented a list of 36 planet candidates
orbiting 31 stars in K2 Campaign 1. In this contribution, we present stellar
and planetary properties for all systems. We combine ground-based
seeing-limited survey data and adaptive optics imaging with an automated
transit analysis scheme to validate 21 candidates as planets, 17 for the first
time, and identify 6 candidates as likely false positives. Of particular
interest is K2-18 (EPIC 201912552), a bright (K=8.9) M2.8 dwarf hosting a 2.23
\pm 0.25 R_Earth planet with T_eq = 272 \pm 15 K and an orbital period of 33
days. We also present two new open-source software packages which enable this
analysis. The first, isochrones, is a flexible tool for fitting theoretical
stellar models to observational data to determine stellar properties using a
nested sampling scheme to capture the multimodal nature of the posterior
distributions of the physical parameters of stars that may plausibly be
evolved. The second is vespa, a new general-purpose procedure to calculate
false positive probabilities and statistically validate transiting exoplanets.Comment: 17 pages, 5 figures, 5 tables, accepted for publication in the
Astrophysical Journal. Updated to closely reflect published version in ApJ
(2015, 809, 25
Semi-classical Characters and Optical Model Description of Heavy Ion Scattering, Direct Reactions, and Fusion at Near-barrier Energies
An approach is proposed to calculate the direct reaction (DR) and fusion
probabilities for heavy ion collisions at near-Coulomb-barrier energies as
functions of the distance of closest approach D within the framework of the
optical model that introduces two types of imaginary potentials, DR and fusion.
The probabilities are calculated by using partial DR and fusion cross sections,
together with the classical relations associated with the Coulomb trajectory.
Such an approach makes it possible to analyze the data for angular
distributions of the inclusive DR cross section, facilitating the determination
of the radius parameters of the imaginary DR potential in a less ambiguous
manner. Simultaneous -analyses are performed of relevant data for the
O+Pb system near the Coulomb-barrier energy
Thin-film flow in helically wound rectangular channels with small torsion
Laminar gravity-driven thin-film flow down a helically-wound channel of rectangular cross-section with small torsion in which the fluid depth is small is considered. Neglecting the entrance and exit regions we obtain the steady-state solution that is independent of position along the axis of the channel, so that the flow, which comprises a primary flow in the direction of the axis of the channel and a secondary flow in the cross-sectional plane, depends only on position in the two-dimensional cross-section of the channel. A thin-film approximation yields explicit expressions for the fluid velocity and pressure in terms of the free-surface shape, the latter satisfying a non-linear ordinary differential equation that has a simple exact solution in the special case of a channel of rectangular cross-section. The predictions of the thin-film model are shown to be in good agreement with much more computationally intensive solutions of the small-helix-torsion Navier–Stokes equations. The present work has particular relevance to spiral particle separators used in the mineral-processing industry. The validity of an assumption commonly used in modelling flow in spiral separators, namely that the flow in the outer region of the separator cross-section is described by a free vortex, is shown to depend on the problem parameters
Earth resources-regional transfer activity contracts review
A regional transfer activity contracts review held by the Earth Resources Office was summarized. Contracts in the earth resources field primarily directed toward applications of satellite data and technology in solution of state and regional problems were reviewed. A summary of the progress of each contract was given in order to share experiences of researchers across a seven state region. The region included Missouri, Kentucky, Tennessee, Mississippi, Alabama, Georgia, and North Carolina. Research in several earth science disciplines included forestry, limnology, water resources, land use, geology, and mathematical modeling. The use of computers for establishment of information retrieval systems was also emphasized
How Engaged are our Students? Using Analytics to Identify Students-at-Risk
Learning Management System (LMS) analytics have become an area of increasing interest and development. The potential to better understand our students’ levels of engagement provided by the systems have, to date, has been underutilized information resources. The study reported here looks at the relationship of student and staff engagement in the LMS and considers the levels of predictability in student behavior leading to failure. Also considered is the impact of the lecturer on the student engagement of poor and high performing students
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Consolidation of Geologic Studies of Geopressured-Geothermal Resources in Texas
Detailed structural mapping at several horizons in selected study areas within the Frio growth-fault trend demonstrates a pronounced variability in structural style. At Sarita in South Texas, shale mobilization produced one or more shale ridges, one of which localized a low-angle growth fault trapping a wedge of deltaic sediments. At Corpus Christi, shale mobilization produced a series of large growth faults, shale-cored domed anticlines, and shale-withdrawal basins, which become progressively younger basinward. At Blessing, major growth faults trap sands of the Greta/Calhoun barrier system, having some discrete shale diapirs but little progradation. At Pleasant Bayou, a major early growth-fault system was overprinted by salt tectonics—the intrusion of Danbury Dome and the development of a salt-withdrawal basin. At Port Arthur, low-displacement, long-lived faults formed on a sand-poor shelf margin contemporaneously with broad salt uplifts and basins. Variability in styles can be related to the nature and extent of Frio sedimentation and shelf-margin progradation and to the presence of salt. Structural styles that are conducive to large geothermal reservoirs include blocks between widely spaced growth faults having dip reversal, salt-withdrawal basins, and shale-withdrawal basins. These styles are widespread on the Texas Gulf Coast. However, actually finding a large reservoir depends on demonstrating the existence of sufficient sand having adequate quality to support geopressured geothermal energy production.Bureau of Economic Geolog
Transforming Assessment Feedback Design: Students’ Responses to Adaptively-Released Assessment Feedback (ARAF) Strategies
The concept of Adaptively-Released Assessment Feedback (ARAF) is relatively new and, to date, has had limited application in the university sector. This article paper looks at the applications of ARAF into the assessment of courses in three different contexts across multiple disciplines at both undergraduate and postgraduate course levels. The article paper outlines the ARAF strategies and their potential for promoting a deeper learning process by enhancing student engagement with feedback. Qualitative data from students are utilized to understand student perceptions of ARAF strategies. Students reported that ARAF increased engagement with assessment feedback and, in some cases, provoked deeper reflection and encouraged them to plan their approach to future assessment tasks. Keywords: quantitative feedback, qualitative feedback, adaptively-released assessment feedback (ARAF) strategies, assessment desig
The risk and protective factors for suicidal burden among 251,763 school-based adolescents in 77 low- and middle-income to high-income countries: assessing global, regional, and national variations - Corrigendum.
BackgroundAdolescent suicide is a global public health concern and the second leading cause of adolescent death worldwide. This study aimed to estimate the burden of adolescent suicidal behaviours and its association with violence and unintentional injury, psychosocial, protective, lifestyle and food security-related factors amongst school-based adolescents across 77 countries in the six World Health Organization (WHO) regions.MethodsThis study comprised a sample of 251 763 adolescents drawn from the latest Global School-based Student Health Survey of school-based adolescents, aged 11-17 years, across 77 countries. Logistic regression analyses were employed to estimate the adjusted effect of independent factors on adolescent suicidal behaviours.ResultsThe population-weighted 12-month prevalence of suicidal ideation (SI), suicidal planning (SP) and suicidal attempts (SA) amongst school-based adolescents was 18, 18 and 16%, respectively. Adolescent suicidal behaviours (i.e. SI, SP and SA) were respectively associated with being physically attacked, physical fighting, high levels of anxiety, feeling lonely, being bullied, lack of parental support, poor peer support, not having close friends and high levels of sedentary behaviours. Overall, these associations also extended to the context of food insecurity across regions and country income groups, where the magnitude of association slightly varied from odds ratios of 1.25 times to 3.13.ConclusionsThe burden of school-going adolescent suicidal thoughts, suicide planning and suicide attempts is of particular concern in low-resource countries. Comprehensive suicide prevention programmes for school-going adolescents in LMICs are needed that address socio-cultural inequities related to violence and unintentional injury, social support and psychological factors, protective, and lifestyle-related factors
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