987 research outputs found
Assessing landscape dust emission potential using combined groundâbased measurements and remote sensing data
Modeled estimates of aeolian dust emission can vary by an order of magnitude due to the spatiotemporal heterogeneity of emissions. To better constrain location and magnitude of emissions, a surface erodibility factor is typically employed in models. Several landscape-scale schemes representing surface dust-emission potential for use in models have recently been proposed, but validation of such schemes has only been attempted indirectly with medium-resolution remote sensing of mineral aerosol loadings and high-resolution land-surface mapping. In this study, we used dust-emission source points identified in Namibia with Landsat imagery together with field-based dust-emission measurements using a Portable In-situ Wind Erosion Laboratory (PI-SWERL) wind tunnel to assess the performance of schemes aiming to represent erodibility in global dust-cycle modeling. From analyses of the surface and samples taken at the time of wind tunnel testing, a Boosted Regression Tree analysis identified the significant factors controlling erodibility based on PI-SWERL dust flux measurements and various surface characteristics, such as soil moisture, particle size, crusting degree and mineralogy. Despite recent attention to improving the characterisation of surface dust-emission potential, our assessment indicates a high level of variability in the measured fluxes within similar geomorphologic classes. This variability poses challenges to dust modelling attempts based on geomorphology and/or spectral-defined classes. Our approach using high-resolution identification of dust sources to guide ground-based testing of emissivity offers a valuable means to help constrain and validate dust-emission schemes. Detailed determination of the relative strength of factors controlling emission can provide further improvement to regional and global dust-cycle modeling
Ornamental plants, 1985: a summary of research
Field transplant survival of Amelanchier liners produced by tissue culture / Daniel K. Struve and R. Daniel Lineberger -- An evaluation of strawdust - an alternative growing media / Elton M. Smith and Sharon A. Treaster -- Growth of container grown nursery stock produced in composted municipal sludge amended media / Elton M. Smith and Sharon A. Treaster -- Soil temperature effects on root regeneration of scarlet oak seedlings / Daniel K. Struve arid Bruno C. Moser -- Lighting Viburnum opulus 'Nanum' cuttings to increase winter survival / Elton M. Smith and Sharon A. Treaster -- Treatments of etiolated dormant rose shoots / Elton M. Smith and Sharon A. Treaster -- Evaluation of flowering crabapple susceptibility to apple scab in Ohio â 1984 / Elton M. Smith and Sharon A. Treaster -- Tolerance of azalea, cotoneaster, and euonymus to Devrinol, Goal, and Goal Combinations / Elton M. Smith and Sharon A. Treaster -- Micropropagation of chimeral african violets / R. Daniel Lineberger and Mark Druckenbrod -- capital requirements of overwintering structures for nurseries in Ohio - 1984 / Reed D. Taylor, Daryl T. Gillette, and Elton M. Smith -- annual fixed costs of overwintering plants in nurseries differentiated by type of structure for Ohio - 1984 / Daryl T. Gillette, Reed D. Taylor, and Elton M. Smith -- Comparative costs of overwintering plants in nurseries differentiated by system for Ohio - 1984 / Reed D. Taylor, Daryl T. Gillette, and Elton M. Smit
Efficacy of Female Rat Models in Translational Cardiovascular Aging Research
Cardiovascular disease is the leading cause of death in women in the United States. Aging is a primary risk factor for the development of cardiovascular disease as well as cardiovascular-related morbidity and mortality. Aging is a universal process that all humans undergo; however, research in aging is limited by cost and time constraints. Therefore, most research in aging has been done in primates and rodents; however it is unknown how well the effects of aging in rat models translate into humans. To compound the complication of aging gender has also been indicated as a risk factor for various cardiovascular diseases. This review addresses the systemic pathophysiology of the cardiovascular system associated with aging and gender for aging research with regard to the applicability of rat derived data for translational application to human aging
Parental ethnic identity and child test scores
We examine the relationship between parental ethnic identity and the test scores of ethnic minority children. We use standard survey measures of the strength of parental identity alongside validated cognitive test scores in a rich British cohort study. We show that children whose mothers report either an adoption or an active rejection of the majority identity tend to score lower in cognitive tests at age 7, compared to those children whose mothers report neutral feelings about the majority identity. We find no consistent differences in test scores according to mothersâ minority identity. Our findings provide no support for education or citizenship policies which promote the adoption of the majority identity or discourage the maintenance of separate identities in ethnic minority communities
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The reaction between silylene and ammonia: some gas-phase kinetic and quantum chemical studies
Time-resolved kinetic studies of the reaction of silylene, SiH2, generated by 193 nm laser flash photolysis of silacyclopent-3-ene, have been carried out in the presence of ammonia, NH3. Second order kinetics were observed. The reaction was studied in the gas phase at 10 Torr total pressure in SF6 bath gas at each of the three temperatures, 299, 340 and 400 K. The second order rate constants (laser pulse energy of 60 mJ/pulse) fitted the Arrhenius equation:
log(k/cm3 molecule-1 s-1) = (-10.37 ± 0.17) + (0.36 ± 1.12 kJ mol-1)/RTln10
Experiments at other pressures showed that these rate constants were unaffected by pressure in the range 10-100 Torr, but showed small decreases in value at 3 and 1 Torr. There was also a weak intensity dependence, with rate constants decreasing at laser pulse energies of 30 mJ/pulse. Ab initio calculations at the G3 level of theory, show that SiH2 + NH3 should form an initial adduct (donor-acceptor complex), but that energy barriers are too great for further reaction of the adduct. This implies that SiH2 + NH3 should be a pressure dependent association reaction. The experimental data are inconsistent with this and we conclude that SiH2 decays are better explained by reaction of SiH2 with the amino radical, NH2, formed by photodissociation of NH3 at 193 nm. The mechanism of this previously unstudied reaction is discussed
Hierarchically coupled ultradian oscillators generating robust circadian rhythms
Ensembles of mutually coupled ultradian cellular oscillators have been proposed by a number of authors to explain the generation of circadian rhythms in mammals. Most mathematical models using many coupled oscillators predict that the output period should vary as the square root of the number of participating units, thus being inconsistent with the well-established experimental result that ablation of substantial parts of the suprachiasmatic nuclei (SCN), the main circadian pacemaker in mammals, does not eliminate the overt circadian functions, which show no changes in the phases or periods of the rhythms. From these observations, we have developed a theoretical model that exhibits the robustness of the circadian clock to changes in the number of cells in the SCN, and that is readily adaptable to include the successful features of other known models of circadian regulation, such as the phase response curves and light resetting of the phase
Distant Voices: Learners' Stories About the Affective Side of Learning a Language at a Distance
Learning a language at a distance has its own special challenges. The remoteness of the learning context can mean isolation for the learner, communication difficulties for the teacher and problems of access for the researcher. Yet distance language learners are likely to be no more skilled in self-regulation than classroom learners, and to require high levels of support. Research tools are needed, therefore, which allow them to talk freely about their learning in order to help distance educators target support appropriately. This paper draws on data from two pilot ethnographic studies of distance language learners using think-aloud protocols to access their thought processes as they tackled two designated language tasks. They were carried out as part of a wider study in each case to investigate aspects of affect including beliefs, motivation and anxiety. The audio-taped voices provided rich insights into the advantages and disadvantages, pleasures and frustrations, comforts and anxieties of learning a language at a distance, and the strategies learners use to manage in a distance environment. The studies underlined the importance of listening to students and using their voices as a basis for discussion on improving aspects of the design and delivery of distance language courses
Evaluation of the selectivity and sensitivity of isoform- and mutation-specific RAS antibodies
Researchers rely largely on antibodies to measure the abundance, activity, and localization of a protein, information that provides critical insight into both normal and pathological cellular functions. However, antibodies are not always reliable or universally valid for the methods in which they are used; in particular, the reliability of commercial antibodies against RAS is highly variable. Waters et al . rigorously assessed 22 commercially available RAS antibodies for their utility to detect the distinct RAS isoforms in various cell types and for their use in specific analytical methods. Their findings show how reliably one can interpret the data acquired from each reagent
Open XAL status Report 2015
Open XAL is an accelerator physics software platform developed in collaboration among several facilities around the world. The Open XAL collaboration was formed in 2010 to port, improve and extend the successful XAL platform used at the Spallation Neutron Source for use in the broader accelerator community and to establish it as the standard platform for accelerator physics software. The site-independent core is complete, active applications have been ported, and now we are in the process of verification and transitioning to using Open XAL in production. This paper will present the current status and a roadmap for this project
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