5,345 research outputs found

    A structural, spectroscopic and theoretical study of the triphenylphosphine chalcogenide complexes of tungsten carbonyl, [W(XPPh3)(CO)5], X=O, S, Se

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    The series [W(XPPh3)(CO)5], X=O, S, Se has been structurally determined by X-ray crystallography and fully characterised spectroscopically to provide data for comparing the bonding of the Ph3PX ligands to the metal. The P-X-W angles are 134.3°, 113.2° and 109.2°, respectively, for X=O, S, Se. The bonding has been analysed using EHMO calculations which suggest that lower P-X-W angles depend on the relative importance of σ-bonding, which in turn depends on the chalcogen in the order X=Se > S > O. The effect is enhanced by lower energies of the metal σ and π orbital energies

    Using Homeland Security Exercise Evaluation Program to Execute a Mass Prophylaxis Exercise in a Rural Community.

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    This project explores the execution of point of distribution exercises in a rural community. Harrison County Iowa is a rural county with a population over 15,000 located approximately 45 minutes north of the Omaha metro area. The project explored the existing point of distribution plans and inventory for the Harrison County Home and Public Health Department. Prior to this project, many staff at Harrison County Home and Public Health Department had no experience with table top or full scale exercises. The mass prophylaxis point of distribution plan had not been updated, and staff had not received training on the point of distribution plan. This project provided a training session on the existing point of distribution plan, a table top exercise, and a full scale exercise for mass dispensing of prophylactic medication. Following the execution of the tabletop and full scale exercise Harrison County Home and Public Health was provided After Action Reports written in Homeland Security Exercise Evaluation style. The project identified areas for improvement such as inclusion of non-english speaking residents and point of distribution site flow. The project also identified strengths in the abilities of Harrison County Home and Public Health to communicate and utilize incident command structure

    Spacecraft command verification: The AI solution

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    Recently, a knowledge-based approach was used to develop a system called the Command Constraint Checker (CCC) for TRW. CCC was created to automate the process of verifying spacecraft command sequences. To check command files by hand for timing and sequencing errors is a time-consuming and error-prone task. Conventional software solutions were rejected when it was estimated that it would require 36 man-months to build an automated tool to check constraints by conventional methods. Using rule-based representation to model the various timing and sequencing constraints of the spacecraft, CCC was developed and tested in only three months. By applying artificial intelligence techniques, CCC designers were able to demonstrate the viability of AI as a tool to transform difficult problems into easily managed tasks. The design considerations used in developing CCC are discussed and the potential impact of this system on future satellite programs is examined

    Revealing Cosmic Rotation

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    Cosmological Birefringence (CB), a rotation of the polarization plane of radiation coming to us from distant astrophysical sources, may reveal parity violation in either the electromagnetic or gravitational sectors of the fundamental interactions in nature. Until only recently this phenomenon could be probed with only radio observations or observations at UV wavelengths. Recently, there is a substantial effort to constrain such non-standard models using observations of the rotation of the polarization plane of cosmic microwave background (CMB) radiation. This can be done via measurements of the BB-modes of the CMB or by measuring its TB and EB correlations which vanish in the standard model. In this paper we show that EBEB correlations-based estimator is the best for upcoming polarization experiments. The EBEB based estimator surpasses other estimators because it has the smallest noise and of all the estimators is least affected by systematics. Current polarimeters are optimized for the detection of BB-mode polarization from either primordial gravitational waves or by large scale structure via gravitational lensing. In the paper we also study optimization of CMB experiments for the detection of cosmological birefringence, in the presence of instrumental systematics, which by themselves are capable of producing EBEB correlations; potentially mimicking CB.Comment: 10 pages, 3 figures, 2 table

    Measuring gravitational lensing of the cosmic microwave background using cross correlation with large scale structure

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    We cross correlate the gravitational lensing map extracted from cosmic microwave background measurements by the Wilkinson Microwave Anisotropy Probe (WMAP) with the radio galaxy distribution from the NRAO VLA Sky Survey (NVSS) by using a quadratic estimator technique. We use the full covariance matrix to filter the data, and calculate the cross-power spectra for the lensing-galaxy correlation. We explore the impact of changing the values of cosmological parameters on the lensing reconstruction, and obtain statistical detection significances at >3σ>3\sigma. The results of all cross correlations pass the curl null test as well as a complementary diagnostic test using the NVSS data in equatorial coordinates. We forecast the potential for Planck and NVSS to constrain the lensing-galaxy cross correlation as well as the galaxy bias. The lensing-galaxy cross-power spectra are found to be Gaussian distributed.Comment: 16 pages, 10 figure

    Improving Group Work: Voices of Students

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    Group work is increasingly being used in a variety of college courses. A number of strengths have driven the increase in the use of this form of collaborative learning. Still, a number of problems potentially limit the use of group projects. In this study, we report on research in which we examined how students recommended changing group projects. Results are categorized into student-centered themes and faculty-centered themes. Implications are provided

    Coral Reef Conservation Program (CRCP) Local Action Strategy (LAS) Project 3B “Southeast Florida Coral Reef Fishery-Independent Baseline Assessment” – 2012-2013 Interim Report

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    Reef fishes are important biologic, ecologic, and economic resources of the marine ecosystem which must be managed for sustainability. Until recently there was no long-term monitoring program in place to assess the condition of fish resources of the northern Florida Reef Tract (FRT) (northern Miami-Dade, Broward, Palm Beach, and Martin counties). An assessment/monitoring plan for the northern Florida reef tract was designed through a joint cooperative effort by scientists at the University of Miami Rosenstiel School of Marine and Atmospheric Science, NOAA-Southeast Fisheries Science Center and Nova Southeastern University Oceanographic Center (NSUOC). This report is a synoptic compilation of the two-year data collection from all partner agencies, and includes data from the 234 and 354 sites or Primary Sampling Units (PSUs) sampled in 2012 and 2013, respectively. The majority of the field work was accomplished through funding granted to NSUOC. Significant amounts of data were also collected by multiple partner agencies that were able to dedicate their time and resources to the project. In 2012 funding for the first year of data collection was awarded by Florida Department of Environmental Protection (FDEP) to NSUOC on July 1st, 2012. Funding for a second year of sampling was awarded by National Oceanic and Atmospheric Administration (NOAA) Coral Reef Conservation Program (CRCP) to NSUOC through the National Coral Reef Institute Cooperative Agreement on June 18, 2013. Field sampling for each year began in May and ran through October. Funding for a third year of data collection (2014) and a final report was awarded by NOAA CRCP to NSUOC. Over the course of the two-year study period for this interim report, \u3e170,000 individual fish of 266 species were recorded. Total mean density for all sites and strata combined for both years was 162 fishes/SSU. For 2012, mean density was 151 fishes/SSU; in 2013 it was 168 fishes/SSU. However, in general, 2012 counts were higher at most sites. When low vs. high slope strata were compared, the high slope strata showed higher fish density. Likewise, species richness was higher at most sites in 2012 than 2013 and was also significantly higher for both years on sites with high slope. Multivariate analyses showed patterns in the reef fish communities associated with benthic habitats. Water depth was a primary determinant of fish distribution with differences in assemblages between shallow and deep sites. Also most of the surveys in the southern regions (Broward-Miami, Deerfield, and South Palm Beach) clustered tightly together indicating high similarity between communities in the deep habitats within these regions. Conversely, fish communities in North Palm Beach and Martin were much more variable and mostly separated in disparate areas of the plot. This suggests that the Martin and North Palm Beach fish communities are distinctly different from the southern regions. The dataset, in its entirety, provides the opportunity for further mining to examine individual species and reef fish assemblage correlations with a host of abiotic and biotic variables. Thus, from both management and ecological-sciences perspectives, it is a valuable resource. It is already clear there are significant differences in the geographic distribution of reef fishes at local and regional scales. There are interacting strata and latitudinal differences in total reef fish abundance, species distribution, sizes, and assemblage structure. The combination of data from all three years will provide a complete regional baseline fishery-independent assessment
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