Mesoscopic spin confinement during acoustically induced transport

Long coherence lifetimes of electron spins transported using moving potential dots are shown to result from the mesoscopic confinement of the spin vector. The confinement dimensions required for spin control are governed by the characteristic spin-orbit length of the electron spins, which must be larger than the dimensions of the dot potential. We show that the coherence lifetime of the electron spins is independent of the local carrier densities within each potential dot and that the precession frequency, which is determined by the Dresselhaus contribution to the spin-orbit coupling, can be modified by varying the sample dimensions resulting in predictable changes in the spin-orbit length and, consequently, in the spin coherence lifetime.Comment: 10 pages, 2 figure

Enhanced Software for Scheduling Space-Shuttle Processing

The Ground Processing Scheduling System (GPSS) computer program is used to develop streamlined schedules for the inspection, repair, and refurbishment of space shuttles at Kennedy Space Center. A scheduling computer program is needed because space-shuttle processing is complex and it is frequently necessary to modify schedules to accommodate unanticipated events, unavailability of specialized personnel, unexpected delays, and the need to repair newly discovered defects. GPSS implements constraint-based scheduling algorithms and provides an interactive scheduling software environment. In response to inputs, GPSS can respond with schedules that are optimized in the sense that they contain minimal violations of constraints while supporting the most effective and efficient utilization of space-shuttle ground processing resources. The present version of GPSS is a product of re-engineering of a prototype version. While the prototype version proved to be valuable and versatile as a scheduling software tool during the first five years, it was characterized by design and algorithmic deficiencies that affected schedule revisions, query capability, task movement, report capability, and overall interface complexity. In addition, the lack of documentation gave rise to difficulties in maintenance and limited both enhanceability and portability. The goal of the GPSS re-engineering project was to upgrade the prototype into a flexible system that supports multiple- flow, multiple-site scheduling and that retains the strengths of the prototype while incorporating improvements in maintainability, enhanceability, and portability

Defect-Free Phononic Crystal Waveguides on GaAs

A phononic crystal waveguide is presented that consists of the inverse of a typical structure. Instead of a defect waveguide within an extended phononic crystal, this waveguide consists of a phononic crystal of finite width, and the phononic crystal itself is composed of a shallow array of holes. The acoustic velocity is actually reduced in the phononic crystal region, which subsequently enables the waveguiding of the acoustic wave underneath the micro-structured surface. As the width of the waveguide increases with the number of inclusions, the waveguide morphs from an unstructured surface to an extended phononic crystal with a transitional modal region of an intermediate number of inclusions that is suitable for waveguiding. For the chosen phononic crystal parameters in terms of the hole depth and filling fraction, the optimum waveguide width of four inclusions is determined

How Does the Gus Schumacher Nutrition Incentive Program Work? A Theory of Change

Increased fruit and vegetable (FV) intake is associated with decreased risk of nutrition-related chronic diseases. Sociodemographic disparities in FV intake indicate the need for strategies that promote equitable access to FVs. The United States Department of Agriculture’s Gus Schumacher Nutrition Incentive Program (GusNIP) supports state and local programs that offer nutrition incentives (NIs) that subsidize purchase of FVs for people participating in the Supplemental Nutrition Assistance Program (SNAP). While a growing body of research indicates NIs are effective, the pathways through which GusNIP achieves its results have not been adequately described. We used an equity-focused, participatory process to develop a retrospective Theory of Change (TOC) to address this gap. We reviewed key program documents; conducted a targeted NI literature review; and engaged GusNIP partners, practitioners, and participants through interviews, workshops, and focus groups in TOC development. The resulting TOC describes how GusNIP achieves its long-term outcomes of increased participant FV purchases and intake and food security and community economic benefits. GusNIP provides NIs and promotes their use, helps local food retailers develop the capacity to sell FVs and accept NIs in accessible and welcoming venues, and supports local farmers to supply FVs to food retailers. The TOC is a framework for understanding how GusNIP works and a tool for improving and expanding the program

Not a melting pot: Plant species aggregate in their non‐native range

AimPlant species continue to be moved outside of their native range by human activities. Here, we aim to determine whether, once introduced, plants assimilate into native communities or whether they aggregate, thus forming mosaics of native‐ and alien‐rich communities. Alien species might aggregate in their non‐native range owing to shared habitat preferences, such as their tendency to establish in high‐biomass, species‐poor areas.LocationTwenty‐two herbaceous grasslands in 14 countries, mainly in the temperate zone.Time period2012?2016.Major taxa studiedPlants.MethodsWe used a globally coordinated survey. Within this survey, we found 46 plant species, predominantly from Eurasia, for which we had co‐occurrence data in their native and non‐native ranges. We tested for differences in co‐occurrence patterns of 46 species between their native (home) and non‐native (away) range. We also tested whether species had similar habitat preferences, by testing for differences in total biomass and species richness of the patches that species occupy in their native and non‐native ranges.ResultsWe found the same species to show different patterns of association depending on whether they were in their native or non‐native range. Alien species were negatively associated with native species; instead, they aggregated with other alien species in species‐poor, high‐biomass communities in their non‐native range compared with their native range.Main conclusionsThe strong differences between the native (home) and non‐native (away) range in species co‐occurrence patterns are evidence that the way in which species associate with resident communities in their non‐native range is not species dependent, but is instead a property of being away from their native range. These results thus highlight that species might undergo important ecological changes when introduced away from their native range. Overall, we show origin‐dependent associations that result in novel communities, in which alien‐rich patches exist within a mosaic of native‐dominated communities.Fil: Stotz, Gisela C.. University of Alberta; CanadáFil: Cahill Jr, James F.. University of Alberta; CanadáFil: Bennett, Jonathan A.. University of Alberta; CanadáFil: Carlyle, Cameron N.. University of Alberta; CanadáFil: Bork, Edward W.. University of Alberta; CanadáFil: Askarizadeh, Diana. University of Tehran; IsraelFil: Bartha, Sandor. Centre for Ecological Research; HungríaFil: Beierkuhnlein, Carl. University of Bayreuth; AlemaniaFil: Boldgiv, Bazartseren. National University of Mongolia; MongoliaFil: Brown, Leslie. University of South Africa; SudáfricaFil: Cabido, Marcelo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Campetella, Giandiego. Universita Degli Di Camerino; ItaliaFil: Chelli, Stefano. Universita Degli Di Camerino; ItaliaFil: Cohen, Ofer. Universitat Tel Aviv; IsraelFil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Enrico, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Ensing, David. Queens University; CanadáFil: Erdenetsetseg, Batdelger. National University of Mongolia; MongoliaFil: Fidelis, Alessandra. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Garris, Heath W.. Covenant College; Estados UnidosFil: Henry, Hugh A. L.. Western Ontario University; CanadáFil: Jentsch, Anke. University of Bayreuth; AlemaniaFil: Hassan, Mohammad. Islamic Azad University; IránFil: Koorem, Kadri. University of Tartu; EstoniaFil: Manning, Peter. Senckenberg Biodiversity and Climate Research Centre; AlemaniaFil: Mitchell, Randall. University of Akron; Estados UnidosFil: Moora, Mari. University of Tartu; EstoniaFil: Overbeck, Gerhard E.. Universidade Federal do Rio Grande do Sul; BrasilFil: Pither, Jason. University of British Columbia; CanadáFil: Reinhart, Kurt O.. United States Department of Agriculture ; Estados UnidosFil: Sternberg, Marcelo. Universitat Tel Aviv; IsraelFil: Tungalag, Radnaakhand. National University of Mongolia; MongoliaFil: Undrakhbold, Sainbileg. National University of Mongolia; MongoliaFil: van Rooyen, Margaretha. University of Pretoria; SudáfricaFil: Wellstein, Camilla. Free University of Bozen; ItaliaFil: Zobel, Martin. University of Tartu; EstoniaFil: Fraser, Lauchlan H.. Thompson Rivers University; Canad

Not a melting pot : plant species aggregate in their non-native range

AIM : Plant species continue to be moved outside of their native range by human activities. Here, we aim to determine whether, once introduced, plants assimilate into native communities or whether they aggregate, thus forming mosaics of native- and alien-rich communities. Alien species might aggregate in their non-native range owing to shared habitat preferences, such as their tendency to establish in high-biomass, species-poor areas. LOCATION : Twenty-two herbaceous grasslands in 14 countries, mainly in the temperate zone. TIME PERIOD : 2012–2016. MAJOR TAXA STUDIED : Plants. METHODS : We used a globally coordinated survey. Within this survey, we found 46 plant species, predominantly from Eurasia, for which we had co-occurrence data in their native and non-native ranges. We tested for differences in co-occurrence patterns of 46 species between their native (home) and non-native (away) range. We also tested whether species had similar habitat preferences, by testing for differences in total biomass and species richness of the patches that species occupy in their native and non-native ranges. RESULTS : We found the same species to show different patterns of association depending on whether they were in their native or non-native range. Alien species were negatively associated with native species; instead, they aggregated with other alien species in species-poor, high-biomass communities in their non-native range compared with their native range. MAIN CONCLUSIONS : The strong differences between the native (home) and non-native (away) range in species co-occurrence patterns are evidence that the way in which species associate with resident communities in their non-native range is not species dependent, but is instead a property of being away from their native range. These results thus highlight that species might undergo important ecological changes when introduced away from their native range. Overall, we show origin-dependent associations that result in novel communities, in which alien-rich patches exist within a mosaic of native-dominated communities.Consejo Nacional de Investigaciones Científicas y Técnicas; Natural Sciences and Engineering Research Council of Canada; Taylor Family-Asia Foundation Endowed Chair in Ecology and Conservation Biology; GINOP-2.3.2-15-2016-00019 project; U.S. National Science Foundation; Universidad Nacional de Córdoba; Natural Sciences and Engineering Research Council of Canada; Fundação Grupo Boticário; National Science Foundation; Asia Foundation; Conselho Nacional de Desenvolvimento Científico e Tecnológico; Estonian Research Council and European Regional Development Fund.http://wileyonlinelibrary.com/journal/gebhj2021Plant Production and Soil Scienc