933 research outputs found
Launch vehicle trajectory optimization computer program, phase 4 Final technical report
Computer program for retrieving stored data and determining variations in launch vehicle performance as function of mission and vehicle parameter
Elementary Teachersā Perceptions of Professional Development Effectiveness
Through continuing education, educators improve their skills and become more proficient at their jobs. However, some educational leaders are unaware of the perception of teachers regarding professional development. Grounded in Desimone and Garetās framework of best practices in teachersā professional development, the purpose of this interpretive qualitative study was to compare that framework to what a sample of teachers believe is effective professional development based on their experiences. Data were interviews with 10 teachers with at least a year of experience in Virginia. The framework was used to compare the theory of what makes effective professional development to the actual experiences of teachers. A deductive thematic approach was used to analyze the data. The themes that emerged from the teachers were active participation, coherence, sustained duration, and collaboration as positive elements of professional development from the conceptual framework, as well as reflection and leadership even though they were not part of the original conceptual framework. Teachers identified having professional development that applies to their work and having choice as reasons they apply their professional development in the classroom. A key recommendation for educational leaders is to use teacher feedback regarding more choice and for professional development to apply to what teachers do in the classroom. Better learning experiences for teachers can lead to better learning experiences for students and promote positive social change in the community
Assessment of Different Contaminants in Freshwater: Origin, Fate and Ecological Impact
Freshwater ecosystems cover over 15% of the world's surface and provide ecosystem services that are pivotal in sustaining human society. However, fast-growing anthropogenic activities have deleterious impacts on these ecosystems. In this Special Issue, we collect ten studies encompassing five different factors of freshwater contamination: landfill leaks, nutrients, heavy metals, emerging organic contaminants and marble slurry. Using different approaches, the studies detailed the direct and indirect effects that these contaminants have on a range of freshwater organisms, from bacteria to vertebrates. Although the papers covered here focused on specific case studies, they exemplify common issues that are expanding in groundwaters, hyporheic zones, streams, lakes and ponds around the world. All the aspects of these issues are in dire need of being continuously discussed among scientists, end-users and policy-makers. To this end, the Special Issue presents a new free software suite for the analysis of the ecological risk and conservation priority of freshwater ecosystems. The software can support local authorities in the preparation of management plans for freshwater basins pursuant to the Water Directives in Europe
Tomographic imaging and scanning thermal microscopy: thermal impedance tomography
The application of tomographic imaging techniques developed for medical applications to the data provided by the scanning thermal microscope will give access to true three-dimensional information on the thermal properties of materials on a mm length scale. In principle, the technique involves calculating and inverting a sensitivity matrix for a uniform isotropic material, collecting ordered data at several modulation frequencies, and multiplying the inverse of the matrix with the data vector. In practice, inversion of the matrix in impractical, and a novel iterative technique is used. Examples from both simulated and real data are given
Launch vehicle trajectory optimization computer program, phase 4 Summary report
Computer program for launch vehicle trajectory optimizatio
Surviving drought: a framework for understanding animal responses to small rain events in the arid zone
Large rain events drive dramatic resource pulses and the complex pulseāreserve dynamics of arid ecosystems change between highārain years and drought. However, aridāzone animal responses to shortāterm changes in climate are unknown, particularly smaller rain events that briefly interrupt longerāterm drought. Using arthropods as model animals, we determined the effects of a small rain event on arthropod abundance in western New South Wales, Australia during a longerāterm shift toward drought. Arthropod abundance decreased over 2 yr, but captures of 10 out of 15 ordinal taxa increased dramatically after the small rain event (\u3c40 \u3emm). The magnitude of increases ranged from 10.4 million% (collembolans) to 81% (spiders). After 3 months, most taxa returned to prerain abundance. However, small soilādwelling beetles, mites, spiders, and collembolans retained high abundances despite the onset of winter temperatures and lack of subsequent rain. As predicted by pulseāreserve models, most aridāzone arthropod populations declined during drought. However, small rain events may play a role in buffering some taxa from declines during longerāterm drought or other xenobiotic influences. We outline the framework for a new model of animal responses to environmental conditions in the arid zone, as some species clearly benefit from rain inputs that do not dramatically influence primary productivity
Expansion of the ligand knowledge base for chelating P,P-donor ligands (LKB-PP)
[Image: see text] We have expanded the ligand knowledge base for bidentate P,P- and P,N-donor ligands (LKB-PP, Organometallics2008, 27, 1372ā1383) by 208 ligands and introduced an additional steric descriptor (nHe(8)). This expanded knowledge base now captures information on 334 bidentate ligands and has been processed with principal component analysis (PCA) of the descriptors to produce a detailed map of bidentate ligand space, which better captures ligand variation and has been used for the analysis of ligand properties
Self-Optimising Reactive Extractions: Towards the Efficient Development of Multi-Step Continuous Flow Processes
Downstream purification of products and intermediates is essential for the development of continuous flow processes. Described herein, is a study on the use of a modular and reconfigurable continuous flow platform for the self-optimisation of reactive extractions and multi-step reaction-extraction processes. The selective extraction of one amine from a mixture of two similar amines was achieved with an optimum separation of 90%, and in this case, the black-box optimisation approach was superior to global polynomial modelling. Furthermore, this methodology was utilised to simultaneously optimise the continuous flow synthesis and work-up of N-benzyl-Ī±-methylbenzylamine with respect to four variables, resulting in a significantly improved purity
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