5,917 research outputs found

    Modelling the Galactic bar using OGLE-II Red Clump Giant Stars

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    Red clump giant stars can be used as distance indicators to trace the mass distribution of the Galactic bar. We use RCG stars from 44 bulge fields from the OGLE-II microlensing collaboration database to constrain analytic tri-axial models for the Galactic bar. We find the bar major axis is oriented at an angle of 24 - 27 degrees to the Sun-Galactic centre line-of-sight. The ratio of semi-major and semi-minor bar axis scale lengths in the Galactic plane x_0, y_0, and vertical bar scale length z_0, is x_0 : y_0 : z_0 = 10 : 3.5 : 2.6, suggesting a slightly more prolate bar structure than the working model of Gerhard (2002) which gives the scale length ratios as x_0 : y_0 : z_0 = 10 : 4 : 3 .Comment: 15 pages, 10 figures, accepted for publication in MNRAS. Supplementary material available online: 10 pages, 10 figure

    Socrates\u27 Evil Associates and the Motivation for his Trial and Condemnation

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    We argue against those who construe the charge made by Polycrates, that Socrates was the teacher of Alcibiades and Critias, to be a substantial feature of the prejudice that Socrates faced as he stood trial for impiety and corrupting the youth

    Web-Based Training for an Evidence-Supported Treatment: Training Completion and Knowledge Acquisition in a Global Sample of Learners

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    The purpose of this investigation is to describe the characteristics of professional and preprofessional learners who registered for and completed TF-CBTWeb, a modular, web-based training program designed to promote the dissemination of Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) and to demonstrate the feasibility of this method of dissemination. Between October 1, 2005, and October 1, 2012, a total of 123,848 learners registered for TF-CBTWeb, of whom 98,646 (79.7%) initiated the learning activities by beginning the first module pretest. Of those, 67,201 (68.1%) completed the full training. Registrants hailed from 130 countries worldwide, and they had varied educational backgrounds, professional identities (both professional and preprofessional), and a range of experience working with child trauma victims. Learners who were from the United States, students, those with master’s degrees, and those with fewer years of experience working with child trauma victims tended to have the highest course completion rates. Learners displayed significant increases in knowledge about each component of TF-CBT, based on module pretest and posttest scores. The advantages and limitations of this web-based training program evaluation are discussed, while important implications for the use of web-based trainings are reviewed

    Autonomous Ground Photographer

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    Dr. Penczykowski, a biology professor at Washington University in St. Louis, researches the effects of powdery mildew on three plant species. Her lab currently collects data in the field by manually counting the number of infected plants with the assistance of a simple PVC grid. Therefore, this projects aims to automate this process by capturing images that can then be processed in her lab after

    Interfacial band-edge energetics for solar fuels production

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    Photoelectrochemical (PEC) water splitting has received growing attention as a potential pathway to replace fossil fuels and produce a clean, renewable, and sustainable source of fuel. To achieve overall water splitting and the associated production of solar fuels, complex devices are needed to efficiently capture light from the sun, separate photogenerated charges, and catalyze reduction and oxidation reactions. To date, the highest performing solar fuels devices rely on multi-component systems, which introduce interfaces that can be associated with further performance loss due to thermodynamic and kinetic considerations. In this review, we identify several of the most important interfaces used in PEC water splitting, summarize methods to characterize them, and highlight approaches to mitigating associated loss mechanisms.The authors thank Dr Eric Miller for the inspiration to compile this review, and the members of the U.S. Department of Energy’s Photoelectrochemical Working Group and Task 35 (Renewable Hydrogen) of the International E nergy Agency’s Hydrogen Imple- menting Agreement for helpful comments, suggestions, and dis- cussions, specifically Prof. Shane Ardo, Dr John Turner, Prof. Dunwei Wang, and Prof. Shannon Boettcher. WAS greatly acknowl- edges funding support from the FOM/NWO/Shell Program on CO 2 - neutral Fuels (Project – APPEL). IDS was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993. NCS acknowledges start-up funds from Lehigh University. JB thanks financial support from GeneralitatValenciana (ISIC/ 2012/008). A summary version of this review paper (DOI: 10.2172/1209498), and associated summary tables that will be updated as the field progresses, will be available on the working group website (http://energy.gov/eere/fuelcells/ photoelectrochemical-working-group)

    The effect of colour vision status on the detection and selection of fruits by tamarins (Saguinus spp.)

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    The evolution of trichromatic colour vision by the majority of anthropoid primates has been linked to the efficient detection and selection of food, particularly ripe fruits among leaves in dappled light. Modelling of visual signals has shown that trichromats should be more efficient than dichromats at distinguishing both fruits from leaves and ripe from unripe fruits. This prediction is tested in a controlled captive setting using stimuli recreated from those actually encountered by wild tamarins (Saguinus spp.). Dietary data and reflectance spectra of Abuta fluminum fruits eaten by wild saddleback (Saguinus fuscicollis) and moustached (Saguinus mystax) tamarins and their associated leaves were collected in Peru. A. fluminum leaves, and fruits in three stages of ripeness, were reproduced and presented to captive saddleback and red-bellied tamarins (Saguinus labiatus). Trichromats were quicker to learn the task and were more efficient at selecting ripe fruits than were dichromats. This is the first time that a trichromatic foraging advantage has been demonstrated for monkeys using naturalistic stimuli with the same chromatic properties as those encountered by wild animal

    Age and sex-specific rates of leaf regeneration in the Mojave Desert moss Syntrichia caninervis

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    The extremely skewed female-biased sex ratio in the desert moss Syntrichia caninervis was investigated by assessing the regeneration capacity of detached leaves. Juvenile, green, yellow-green, and brown leaves equating to approximately 0, 2, 6, and 12 yr of age, respectively, were detached from individuals of S. caninervis collected from 10 field populations and grown in a growth chamber for 58 d at a light intensity of 33–128 µmol · m–2 · s–1. Younger leaves (0–2 yr old) tended to have a greater viability, regenerate more quickly, extend their protonemal filaments farther, produce shoots (gametophores) more quickly, produce more shoots, and accumulate a greater biomass than older leaves (6 and 12 yr old). Among younger leaf classes, regenerating female leaves were more likely to produce a shoot than male leaves and produced more shoots than male leaves. The sexes did not differ significantly in time until protonemal emergence, linear extension of protonemata, or rate of biomass accumulation. However, protonemata of male leaves tended to emerge more quickly and produce a greater total biomass, ultimately consisting mostly of protonemata, than did female leaves. The more rapid proliferation of shoots by female leaf regenerants may help to explain the rarity of males in this species

    Disruption of the GDP-mannose synthesis pathway in Streptomyces coelicolor results in antibiotic hyper-susceptible phenotypes

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    Actinomycete bacteria use polyprenol phosphate mannose as a lipid linked sugar donor for extra-cytoplasmic glycosyl transferases that transfer mannose to cell envelope polymers, including glycoproteins and glycolipids. We showed recently that strains of Streptomyces coelicolor with mutations in the gene ppm1 encoding polyprenol phosphate mannose synthase were both resistant to phage φC31 and have greatly increased susceptibility to antibiotics that mostly act on cell wall biogenesis. Here we show that mutations in the genes encoding enzymes that act upstream of Ppm1 in the polyprenol phosphate mannose synthesis pathway can also confer phage resistance and antibiotic hyper-susceptibility. GDP-mannose is a substrate for Ppm1 and is synthesised by GDP-mannose pyrophosphorylase (GMP; ManC) which uses GTP and mannose-1-phosphate as substrates. Phosphomannomutase (PMM; ManB) converts mannose-6-phosphate to mannose-1-phosphate. S. coelicolor strains with knocked down GMP activity or with a mutation in sco3028 encoding PMM acquire phenotypes that resemble those of the ppm1-mutants i.e. φC31 resistant and susceptible to antibiotics. Differences in the phenotypes of the strains were observed, however. While the ppm1-strains have a small colony phenotype, the sco3028 :: Tn5062 mutants had an extremely small colony phenotype indicative of an even greater growth defect. Moreover we were unable to generate a strain in which GMP activity encoded by sco3039 and sco4238 is completely knocked out, indicating that GMP is also an important enzyme for growth. Possibly GDP-mannose is at a metabolic branch point that supplies alternative nucleotide sugar donors
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