Electronic structure, magnetic structure, and metal-atom site preferences in CrMnAs

Density functional theory was used to examine stoichiometric CrMnAs, one of a class of 3d-metal arsenides that exhibit cooperative magnetic ordering. CrMnAs is a tetragonal structure with two inequivalent metal sites: M(I), which is tetrahedral coordinate, and M(II), which is square pyramidal coordinate. CrMnAs thus presents a “coloring problem,” the question of how the two types of metal atoms are distributed between the two types of metal sites. Previous diffraction studies have determined that CrMnAs is antiferromagnetic with the M(I) site primarily occupied by Cr. TB-LMTO-ASA local density approximation (LDA) calculations showed indications of instability in the nonmagnetic structure, which could be resolved either by structural distortion or by spin polarization. LDA crystal orbital Hamilton population (COHP) curves were used to predict the nature of particular direct-exchange interactions upon spin polarization. Spin-polarized total energy calculations were performed using VASP with the generalized gradient approximation (GGA). The lowest-energy structure had Mn at the M(I) site and a different antiferromagnetic ordering than previously observed. The structure with the second-lowest calculated total energy also had Mn at M(I). Next lowest were four structures with Cr at M(I), including the experimentally observed structure. Those four had calculated total energies ranging from 154.2 to 167.8 meV/f.u. higher than the lowest-energy case. The number of possible structures with small energy differences suggests that the observed magnetic ordering and coloring may be due to entropy rather than reflecting a true electronic ground state

Strange meson production at high density and temperature

The properties of strange mesons ($K$, $\bar K$ and $\bar K^*$) in dense matter are studied using a unitary approach in coupled channels for meson-baryon scattering. The kaon-nucleon interaction incorporates $s$- and $p$-wave contributions within a chiral model whereas the interaction of $\bar K^*$ with nucleons is obtained in the framework of the local hidden gauge formalism. The in-medium solution for the scattering amplitude accounts for Pauli blocking effects, mean-field binding on baryons, and meson self-energies. We obtain the $K$, $\bar K$ and $\bar K^*$ (off-shell) spectral functions in the nuclear medium and study their behaviour at finite density, temperature and momentum. We also analyze the energy weighted sum rules of the kaon propagator as a quality test of model calculations. We finally estimate the transparency ratio of the $\gamma A \to K^+ K^{*-} A^\prime$ reaction, which we propose as a feasible scenario at present facilities to detect in-medium modifications of the $\bar K^*$ meson.Comment: 6 pages, 5 figures, invited seminar in New Frontiers in QCD 2010 -Exotic Hadron Systems and Dense Matter- (NFQCD2010), Kyoto, January 18-March 19, 201

Communicating the economic and environmental impacts of agroforestry systems

Paper presented at the 11th North American Agroforesty Conference, which was held May 31-June 3, 2009 in Columbia, Missouri.In Gold, M.A. and M.M. Hall, eds. Agroforestry Comes of Age: Putting Science into Practice. Proceedings, 11th North American Agroforestry Conference, Columbia, Mo., May 31-June 3, 2009.The Agriculture and Agri-Food Canada Agroforestry Division conducts research, development and delivers technology tools, products and services including tree and shrub seedlings for the adoption and integration of agroforestry practices by producers. The Division works toward increasing the adoption of agroforestry by demonstrating that agroforestry practices can be both environmentally and economically beneficial if properly integrated as a management practice in the agricultural landscape. To do so, it is important to demonstrate the return on investment for the producer, highlighting private benefits, while also determining opportunities that recognize public benefits. Agricultural practices are constantly changing as producers adopt new technologies and adapt to changing markets, social concerns and changing physical environments. Some producers may no longer consider trees in the agricultural landscape necessary as they rely more on adopted technologies and machinery advancements to impact production and environmental issues traditionally addressed by shelterbelts and tree buffers. As farms become larger and demographics of the farm population change, there is less time and traditional labour for producers to plant and care for trees. Agroforestry specialists and development staff must be cognizant of agricultural trends and keep this in mind when developing agroforestry marketing strategies and programming that is directed at producers. Using the AAFC-PFRA Agroforestry Division's Prairie Shelterbelt Program as an example, this presentation will focus on government & producer investment in agroforestry systems and the economic and environmental impacts of agroforestry systems for the producer and on the agricultural landscape.Laura Poppy (1), Janna Lutz (1), and Henry de Gooijer (1) ; 1. Agriculture and Agri-Food Canada, Agroforestry Division, Indian Head, SK, Canada, S0G 2K0.Includes bibliographical references

Charm and Hidden Charm Scalar Resonances in Nuclear Matter

We study the properties of the scalar charm resonances $D_{s0}(2317)$ and $D_0(2400)$, and the theoretical hidden charm state X(3700) in nuclear matter. We find that for the $D_{s0}(2317)$ and X(3700) resonances, with negligible and small width at zero density, respectively, the width becomes about $100 {\rm MeV}$ and $200 {\rm MeV}$ at normal nuclear matter density, accordingly. For $D_0(2400)$ the change in width is relatively less important. We discuss the origin of this new width and trace it to reactions occurring in the nucleus. We also propose a possible experimental test for those modifications in nuclear matter, which will bring valuable information on the nature of those scalar resonances and the interaction of $D$ mesons with nucleons.Comment: 3 pages, 3 figures, to appear in the proceedings of the International Conference on Particles And Nuclei (PANIC08), Eilat, Israel, November 9-14, 200

Innovative agroforestry designs : Ecobuffers

Paper presented at the 12th North American Agroforesty Conference, which was held June 4-9, 2011 in Athens, Georgia.In Ashton, S. F., S.W. Workman, W.G. Hubbard and D.J. Moorhead, eds. Agroforestry: A Profitable Land Use. Proceedings, 12th North American Agroforestry Conference, Athens, GA, June 4-9, 2011.The predominance of large scale agriculture on the Canadian prairies and the introduction of precision farming technology has led to a noticeable reduction in habitat of marginal lands adjacent to agricultural fields. Removal of existing shelterbelts and a reduction in the number of new shelterbelt plantings is also partially a product of increased field and farm implement size. While improved land management techniques such as zero tillage can help mitigate the negative impact of the loss of shelterbelts, the positive functionality of agroforestry systems cannot be adequately replaced by monocultural farming practices. It is therefore important to target research and development on new agroforestry designs that will fit into modern farming practices. The AAFC Agroforestry Development Centre is conducting research and development on new multi-functional tree planting designs, particularly along field boundaries and riparian zones. The function of the new designs is for multiple purposes including enhancing biodiversity and water quality, conserving soil, biomass production, sequestering carbon and providing economic returns. Three alternative planting designs are being evaluated and demonstrated for their ability to be successfully integrated into current farming systems; ecological buffers (ECOBUFFERS), forest belts and willow buffers. Ecobuffers are a narrow, densely mixed shelterbelt that use native species to mimic natural hedgerows in design and function. Forest Belts are multi species in design, based on traditional plant spacings and willow buffers consist of multiple linear rows of willow cuttings planted in a dense arrangement along riparian areas acting as effective interceptors of nutrients and a source of renewable on farm bio-energy. Only ecobuffers will be addressed in this paper.Bill Schroeder (1), Dan Walker (1), Garth Inouye (1), Laura Poppy (1) and Janna Lutz (1) ; 1. Agriculture and Agri-Food Canada (AAFC), Agroforestry Development Centre, Indian Head, Saskatchewan, Canada.Includes bibliographical references

Factors Associated with Immunization Opinion Leadership among Men Who Have Sex with Men in Los Angeles, California

We sought to identify the characteristics of men who have sex with men (MSM) who are opinion leaders on immunization issues and to identify potential opportunities to leverage their influence for vaccine promotion within MSM communities. Using venue-based sampling, we recruited and enrolled MSM living in Los Angeles (N = 520) from December 2016 to February 2017 and evaluated characteristic differences in sociodemographic characteristics, health behaviors, and technology use among those classified as opinion leaders versus those who were not. We also asked respondents about their past receipt of meningococcal serogroups A, C, W, and Y (MenACWY) and meningococcal B (MenB) vaccines, as well as their opinions on the importance of 13 additional vaccines. Multivariable results revealed that non-Hispanic black (aOR = 2.64; 95% CI: 1.17–5.95) and other race/ethnicity (aOR = 2.98; 95% CI: 1.41–6.29) respondents, as well as those with a history of an STI other than HIV (aOR = 1.95; 95% CI: 1.10–3.48), were more likely to be opinion leaders. MenACWY (aOR = 1.92; 95% CI: 1.13–3.25) and MenB (aOR = 3.09; 95% CI: 1.77–5.41) vaccine uptake, and perceived importance for these and seven additional vaccines, were also associated with being an opinion leader. The results suggest that the co-promotion of vaccination and other health promotion initiatives via opinion leaders could be a useful strategy for increasing vaccination among MSM

Mass flow of per- and polyfluoroalkyl substances (PFAS) in a Swedish municipal wastewater network and wastewater treatment plant

Per: and polyfluoroalkyl substances (PFAS) are ubiquitously distributed in wastewater, due to their numerous uses in industry and consumer products, but little is known of PFAS mass flows in municipal wastewater network systems and within wastewater treatment plants (WWTPs). This study assessed mass flows of 26 PFAS in a wastewater network and WWTP, to provide new insights into their sources, transport, and fate in different treatment steps. Wastewater and sludge samples were collected from pumping stations and the main WWTP in Uppsala, Sweden. PFAS composition profiles and mass flows were used to identify sources within the sewage network. Wastewater from one pumping station showed elevated concentrations of C3–C8 PFCA, likely caused by an industrial source, and two stations had elevated concentrations of 6:2 FTSA, probably originating from a nearby firefighter training facility. Within the WWTP, short-chain PFAS dominated in wastewater, whereas longchain PFAS dominated in sludge. The ratio of perfluoroalkyl sulfonates (PFSA) and ethylperfluorooctanesulfonamidoacetic acid (EtFOSAA) to ∑26PFAS decreased during the WWTP process, likely due to sorption to sludge, but also transformation (EtFOSAA). Overall, PFAS were not efficiently removed in the WWTP, with mean removal efficiency of 10 ± 68% for individual PFAS, resulting in discharge of 7000 mg d− 1 ∑26PFAS into the recipient. This shows that conventional WWTPs are inefficient in removing PFAS from wastewater and sludge, so advanced treatment techniques are needed

Partial wave contributions to the antikaon potential at finite momentum

The momentum dependence of the antikaon optical potential in nuclear matter is obtained from a microscopic and self-consistent calculation using the meson-exchange J\"ulich $\bar{K}N$ interaction. Two self-consistent schemes are discussed, which would lead to substantially different predictions for the width of ${\bar K}$ nuclear bound states. The effect of higher partial waves of the $\bar{K}N$ interaction, beyond the L=0 component, is studied and found to have moderate but non-negligible effects on the ${\bar K}$ nuclear potential at zero momentum. At momenta as large as 500 MeV/c, relevant in the analysis of heavy-ion collisions, the higher partial partial waves modify the ${\bar K}$ optical potential by nearly a factor of two.Comment: 20 pages, 7 figure

Understanding greenways in Central Iowa: an analysis of knowledge, perceptions, and attitudes of stakeholder groups involved with the Central Iowa Greenways Framework Plan

With the rapid conversion of land from open space to developed parcels, in Iowa and across the United States, greenways are becoming a popular and important tool for protecting land resources. Greenways are linear open space corridors, usually vegetated and often along rivers. They can serve as wildlife habitat and movement corridors, as recreation via trails, and as a place to get away from the city. Recently, a greenways framework plan was developed for Central Iowa, including Dallas, Polk, Story, and Warren Counties. The initiative for the plan was led by the four county conservation boards, cities of Des Moines\u27 and West Des Moines\u27 Parks and Recreation Department, and the Iowa Natural Heritage Foundation; these groups are collectively known as the Central Iowa Greenways (CIG) Committee. The plan involved various stakeholders in the area, but was the first time a regional greenway plan has been developed in Iowa. The purpose of this study was to expand the work started by this plan by understanding the knowledge, perceptions, and attitudes of the stakeholders in the area. The information from the study is meant to aid the CIG Committee in implementation of the project. A series of interviews was conducted with both the CIG Committee and stakeholders. The interviews helped to gather information about the people\u27s understanding of greenways, priority of greenways compared to other community issues, and support for particular greenway implementation strategies were obtained. Information regarding the planning process that was undertaken to complete the framework plan was also obtained. A comparison of the planning process, resulting plan, and the information from the interviews was completed. The result was a critique of the plan and a set of recommendations to help the Central Iowa Greenways Committee in their pursuit of a regional greenway as well as an in-depth data set relating to understanding of and support for greenways in Central Iowa among the stakeholders

The Cepheid Period-Luminosity Relation at Mid-Infrared Wavelengths: I. First-Epoch LMC Data

We present the first mid-infrared Period-Luminosity (PL) relations for Large Magellanic Cloud (LMC) Cepheids. Single-epoch observations of 70 Cepheids were extracted from Spitzer IRAC observations at 3.6, 4.5, 5.8 and 8.0 microns, serendipitously obtained during the SAGE (Surveying the Agents of a Galaxy's Evolution) imaging survey of the LMC. All four mid-infrared PL relations have nearly identical slopes over the period range 6 - 88 days, with a small scatter of only +/-0.16 mag independent of period for all four of these wavelengths. We emphasize that differential reddening is not contributing significantly to the observed scatter, given the nearly two orders of magnitude reduced sensitivity of the mid-IR to extinction compared to the optical. Future observations, filling in the light curves for these Cepheids, should noticeably reduce the residual scatter. These attributes alone suggest that mid-infrared PL relations will provide a practical means of significantly improving the accuracy of Cepheid distances to nearby galaxies.Comment: 19 pages, 4 figures, 1 table, Accepted for publication in the Astrophysical Journa