2,529 research outputs found

    Editorial

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    A series of N-heterocyclic carbene (NHC)/PR3 palladium(II) and palladium(0) complexes has been synthesized and fully characterized. X-ray crystallographic data have allowed comparison of ligand steric properties. The NHC ligand was found to vary its steric properties as a function of the phosphine co-ligand. These complexes display interesting catalytic properties in the Suzuki-Miyaura reaction performed in aqueous media. The pre-catalyst [PdCl2(IPr)(XPhos)] (IPr = N,N'-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene; XPhos = 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl) was found to be the most efficient system, promoting the coupling of a wide range of aryl chlorides with boronic acids in aqueous media with a typical catalyst loading of 0.03 mol%

    Collecting Valuable Data for Useful Stream Assessment and Restoration Design Projects

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    Proceedings of the 2003 Georgia Water Resources Conference, held April 23-24, 2003, at the University of Georgia.Stream assessments and restoration projects are becoming increasingly important to meet water quality standards and protect biological health. Developing an assessment methodology that is both effective and efficient is the first crucial step in conducting a stream inventory to identify watershed based problems and develop restoration designs to improve stream system health. ENTRIX has worked on several projects involving stream assessment and restoration design and is continually improving on the type of data collected, how the data is collected, and how project benefits are quantified. This approach includes the following steps: 1) Field investigation to identify and assess watershed conditions 2) Data summary to prioritize and rank stream reaches based on the results of the field assessment 3) Develop a list of potential improvement projects 4) Quantify benefits and rank projects based on costs and benefits. This presentation will focus on recent improvements in the methods used for stream assessment and restoration design projects

    Wildlife Damage to Seedlings in Reforested in Hardwood Sites in Mississippi

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    Herbivory assessments were conducted on seven reforested sites that were less than one year old in the following Mississippi counties: Bolivar, Leflore, and Attala. At each site, 100ft. x 100 ft. plots were established and randomly selected seedlings were marked and measured to determine seedling species, height, condition, survival, and type and extent of animal feeding sign. Surveys were conducted in March/April, May, and August 2004. Herbivory rates were highest during May with approximately 47% of seedlings showing signs of herbivory. In March/ April and August, the percentage of seedlings exhibiting signs of herbivory was 37% and 30%, respectively. Foraging by white-tailed deer (Odocoileus virginianus) was recorded on \u3e 90% of the damaged seedlings during each survey. Tree mortality for all study sites and tree species was negligible, with the highest amount (7%) recorded during August, despite the recorded rates of herbivory by white-tailed deer. Herbivory by rabbits (Sylvilagus spp.) and rodents occurred on approximately 6% of the seedlings throughout the 2004 growing season

    Ultrafast and Coherent Dynamics in a Solvent Switchable “Pink Box” Perylene Diimide Dimer

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    Perylene diimide (PDI) dimers and higher aggregates are key components in organic molecular photonics and photovoltaic devices, supporting singlet fission and symmetry breaking charge separation. Detailed understanding of their excited states is thus important. This has proven challenging because interchromophoric coupling is a strong function of dimer architecture. Recently, a macrocyclic PDI dimer was reported in which excitonic coupling could be turned on and off simply by changing the solvent. This presents a useful case where coupling is modified without synthetic changes to tune supramolecular structure. Here we present a detailed study of solvent dependent excited state dynamics in this dimer by means of coherent multidimensional spectroscopy. Spectral analysis resolves the different coupling strengths, which are consistent with solvent dependent changes in dimer conformation. The strongly coupled conformer forms an excimer within 300 fs. The low‐frequency Raman active modes recovered from two‐dimensional electronic spectra reveal frequencies characteristic of exciton coupling. These are assigned to modes modulating the coupling from the corresponding DFT calculations. Further analysis reveals a time dependent frequency during excimer formation. Analysis of two‐dimensional “beatmaps” reveals features in the coupled dimer which are not predicted by the displaced harmonic oscillator model and are assigned to vibronic coupling

    Review of the effectiveness of on-site habitat management to reduce atmospheric nitrogen deposition impacts on terrestrial habitats

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    1. Given the widespread impacts on habitats in the UK it is essential to understand how habitat management measures could mitigate N deposition impacts and promote recovery. This project reviews the effectiveness of ‘on-site’ land management methods to mitigate nitrogen deposition impacts on sensitive habitats; assesses what effect current management practice has on habitat response to nitrogen deposition; considers how measures may be affected by climate change; and recommends realistic and practical management measures for different habitat types which could be used to mitigate nitrogen impacts or speed recovery. 2. The potential for management to mitigate N deposition impacts was considered across the following broad habitats: broadleaved, mixed and yew woodland & (natural) coniferous woodland; neutral grassland; calcareous grassland; acid grassland; dwarf shrub heath; bog; coastal dunes and slacks; other coastal habitats. For all habitats we were able to identify management techniques with some potential to mitigate N deposition impacts. 3. Management techniques may improve habitat suitability (e.g. control dominant species), remove nitrogen from the system, or both. 4. However, all management techniques also have unintended consequences meaning that their implementation might conflict with other conservation priorities. 5. There are a range of schemes and handbooks providing habitat management advice in the UK. The following techniques were reviewed in detail: grazing; cutting; burning; fertilisation; liming; hydrological management; scrub and tree management; disturbance. 6. Current management may already be partially offsetting the impact of N deposition. 7. Management for N is unlikely to make habitats more vulnerable to climate change. There is complementarity in the management options required to tackle N deposition and climate change. The frequency or intensity of measures such as grazing, cutting or burning will all need to increase. Regional variation in climate change may lead to different emphasis of management options in the wetter north west and the drier south east. 8. Climate change will alter habitat sensitivity to N deposition, via changes in ecosystem processes. Overall, climate change will make woodlands less sensitive to N deposition, but will make heathlands more sensitive to N deposition. Effects on other habitats have not yet been evaluated. 9. There is some potential for mitigating the impacts of N deposition through on-site management although this varies greatly between habitat and management practice. It is likely that small changes in management and adherence to appropriate guidelines could partially improve habitat suitability and/or increase N removal. 10. The majority of management practices do not remove significant quantities of N (with the exception of removing biomass or topsoil). Furthermore, management of a suitable intensity to remove sufficient N to fully offset N added by atmospheric deposition is likely to damage the habitat and result in a number of unintended consequences. 11. Further research is needed to determine the impacts of individual management practices on the N budget in different habitats. Further research is also needed to explore the potential for novel management techniques to remove N from sites. 12. For an individual site where N is identified as a pressure, a manager can look at current management and compare this with the management recommendations in the report to make changes where appropriate. 13. All management recommendations that remove N from the site move it elsewhere and have the potential for unintended consequences. Consequently there is no substitute for reducing the amount of N deposited onto a site which can only be achieved through emission controls

    Dust heating sources in galaxies: the case of M33 (HERM33ES)

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    Dust emission is one of the main windows to the physics of galaxies and to star formation as the radiation from young, hot stars is absorbed by the dust and reemitted at longer wavelengths. The recently launched Herschel satellite now provides a view of dust emission in the far-infrared at an unequaled resolution and quality up to 500 \mu m. In the context of the Herschel HERM33ES open time key project, we are studying the moderately inclined Scd local group galaxy M33 which is located only 840 kpc away. In this article, using Spitzer and Herschel data ranging from 3.6 \mu m to 500 \mu m, along with HI, H\alpha\ maps, and GALEX ultraviolet data we have studied the emission of the dust at the high spatial resolution of 150 pc. Combining Spitzer and Herschel bands, we have provided new, inclination corrected, resolved estimators of the total infrared brightness and of the star formation rate from any combination of these bands. The study of the colors of the warm and cold dust populations shows that the temperature of the former is, at high brightness, dictated by young massive stars but, at lower brightness, heating is taken over by the evolved populations. Conversely, the temperature of the cold dust is tightly driven by the evolved stellar populations.Comment: 29 pages, 12 figures, accepted for publication in A

    Bridging the Gaps: Building a University Link Tank

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    This project proposed a University Link Tank as a mechanism by which to build bridges between employees via a network of small groups. Participation in the Link Tank would be voluntary and open to all VCU and Health System employees. The program would be modeled similarly to the Faculty Learning Community (FLC) program, which is administered by the Center for Teaching Excellence, but it would concentrate on issues that are not specifically related to teaching. Topics will be proposed annually. The program would also concentrate on effectively utilizing existing VCU resources to resolve issues

    Group-based motivational interviewing for alcohol use among college students: An exploratory study.

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    How can practicing psychologists help reduce excessive alcohol consumption among college students? Over 80 % of college students consume alcohol, and a significant percentage drinks excessively with myriad problems. Brief interventions based on motivational interviewing (MI) have been identified for use with college populations. The authors randomly assigned 91 freshman students to a brief, classroom-based MI intervention or an assessment control condition. At the end of the semester, MI group participants reported fewer drinks per occasion and fewer episodes of intoxication compared to controls. A classroom-based, MI-style intervention might be an efficient, sustainable, and effective means of reducing heavy drinking among college students
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