1,424 research outputs found

    Effect of Herbivory on the Growth and Competitive Ability of Reed Canary Grass (Phalaris arundinacea)

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    Herbivory plays an important role in plant community structure in many ecosystems through preferential selection, plant regrowth, and seed transport. Phalaris arundinacea, reed canary grass, is a prevalent wetland invasive species consumed by geese, muskrats, and snails. We lack a clear understanding of how herbivory impacts P. arundinacea\u27s invasion potential. Therefore, I sought to understand the effect of herbivory by generalist macrograzers and micrograzers on the competitive dominance of P. arundinacea in created wetlands, especially the degree to which herbivory alters the competitive relationship between P. arundinacea and Typha latifolia (broadleaf cattail). To address this enclosure/exclosure cages were constructed in June 2013. Half of the plots contained only P. arundinacea and half were placed along the edge between P. arundinacea and T. latifolia. In caged treatments, amber snails (Succinea putris) were either included or removed. Control plots without cages assessed the effect of larger grazers. I predicted that herbivory would negatively impact the growth of P. arundinacea, and mixed plots would allow T. latifolia to spread into the P. arundinacea zone. Choice experiments were conducted with Branta canadensis, Canada geese, and S. putris to evaluate their preference for P. arundinacea or T. latifolia. I did not find any significant differences in P. arundinacea growth due to grazing but competition with T. latifolia did impact P. arundinacea. Edge plots at RIT had a significantly reduced growth rate compared to stems from plots containing P. arundinacea only. In choice experiments, geese showed a preference for P. arundinacea over Typha, whereas snails showed no preference. Despite the observed preference, I was unable to demonstrate effects of herbivory in the field. Herbivory appears to play a minor role in P. arundinacea\u27s success as an invasive plant in created wetlands, with other factors, such as competition for light and nutrients of potentially greater importance

    L-band ATS 5/Orion/S. S. Manhattan marine navigation and communication experiment Final report

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    L-band signals relayed by synchronous satellite for navigation and data communicatio

    The leading asymptotic terms of the three-body Coulomb scattering wave function

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    The asymptotic wave function derived by Alt and Mukhamedzhanov [Phys. Rev. A 47, 2004 (1993)] and Mukhamedzhanov and Lieber [Phys. Rev. A 54, 3078 (1996)] has been refined in the region where the pair (ÎČ,Îł) (\beta,\gamma) remains close to each other while the third particle α\alpha is far away from them (ρα→∞(\rho_{\alpha} \to \infty, rα/ρα→0)r_{\alpha}/\rho_{\alpha}\to 0). The improved wave function satisfies the Schr\"odinger equation up to the terms of order O(1/ρα3)O(1/{\rho_{\alpha}}^{3}), provides the leading asymptotic terms of the three-body scattering wave function with Coulomb interactions and gives further insight into the continuum behavior of the three-charged-particle wave function and helps to obtain 3→33\to 3 scattered wave. This opens up further ways of solving and analysing the three-body Schr\"odinger equation by numerical means

    EXPERIMENTATION SCIENCE: A PROCESS APPROACH FOR THE COMPLETE DESIGN OF AN EXPERIMENT

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    Experimentation Science is introduced as a process through which the necessary steps of experimental design are all sufficiently addressed. Experimentation Science is defined as a nearly linear process of objective formulation, selection of experimentation unit and decision variable(s), deciding treatment, design and error structure, defining the randomization, statistical analyses and decision procedures, outlining quality control procedures for data collection, and finally analysis, presentation and interpretation of results. The protocol description form (PDF) is introduced as an instrument to guide the implementation and documentation of the Experimentation Science process

    Surface reconstructions and atomic ordering in In<sub>x</sub>Ga<sub>1-x</sub>As(001) films: A density-functional theory study

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    Density-functional theory calculations were carried out for various surface reconstructions of atomically ordered thin films of InxGa1−xAs on the InP(001) substrate for compositions close to x=1/2. In addition to the known (n x 3) and (2 x 4) reconstructions, a gallium-rich ζ(4 x 2) reconstruction, so far only observed for binary arsenides, is predicted. Moreover, the possibility of a c(4 x 4) reconstruction, either purely terminated by As-As dimers or mixed with heterodimers, as well as the possible occurrence of heterodimers in other reconstructions have been investigated. From our calculated film formation energies, these reconstructions are expected to play a minor role for InxGa1−xAs films under thermodynamic equilibrium conditions. For the surface-induced atomic ordering in the InxGa1−xAs films, our calculations are in line with known trends for InxGa1−xP alloys. In general, the energetic preference for near-surface ordering in the InxGa1−xAs system is found to be somewhat weaker than in the InxGa1−xP system

    Development of a tailored, telehealth intervention to address chronic pain and heavy drinking among people with HIV infection: integrating perspectives of patients in HIV care.

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    BACKGROUND: Chronic pain and heavy drinking commonly co-occur and can infuence the course of HIV. There have been no interventions designed to address both of these conditions among people living with HIV (PLWH), and none that have used telehealth methods. The purpose of this study was to better understand pain symptoms, patterns of alcohol use, treatment experiences, and technology use among PLWH in order to tailor a telehealth intervention that addresses these conditions SUBJECTS: Ten participants with moderate or greater chronic pain and heavy drinking were recruited from a cohort of patients engaged in HIV-care (Boston Alcohol Research Collaborative on HIV/AIDS Cohort) and from an integrated HIV/primary care clinic at a large urban hospital. METHODS: One-on-one interviews were conducted with participants to understand experiences and treatment of HIV, chronic pain, and alcohol use. Participants’ perceptions of the infuence of alcohol on HIV and chronic pain were explored as was motivation to change drinking. Technology use and treatment preferences were examined in the fnal section of the interview. Interviews were recorded, transcribed and uploaded into NVivo¼ v12 software for analysis. A codebook was developed based on interviews followed by thematic analysis in which specifc meanings were assigned to codes. RESULTS: A number of themes were identifed that had implications for intervention tailoring including: resilience in coping with HIV; autonomy in health care decision-making; coping with pain, stress, and emotion; understanding treatment rationale; depression and social withdrawal; motives to drink and refrain from drinking; technology use and capacity; and preference for intervention structure and style. Ratings of intervention components indicated that participants viewed each of the proposed intervention content areas as “helpful” to “very helpful”. Videoconferencing was viewed as an acceptable modality for intervention delivery CONCLUSIONS: Results helped specify treatment targets and provided information about how to enhance intervention delivery. The interviews supported the view that videoconferencing is an acceptable telehealth method of addressing chronic pain and heavy drinking among PLWH.UH2 AA026192 - NIAAA NIH HHSPublished versio

    The Social Network Position of Lead Users

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    The field of lead user research has seen a great deal of attention from academics and practitioners alike. However, we still lack a full understanding of the nature of users with high potential for innovation. In this paper, we employ a social network perspective on lead users. Increasing the realism of our research in three empirical studies with different empirical settings and methods, we provide robust evidence that lead users have a distinctive social network position: They exhibit an unusually high level of "betweenness centrality", meaning that they are positioned as bridges between different social groups. This finding has two major implications for lead user theory. First, it consolidates seminal conceptual work on lead users and their embeddedness in social networks. And second, the findings extend and validate prior work on the social network perspective of lead users by combining theoretical insights from cognitive psychology, research on creativity, and network theory. As the social network positions of individuals can be mapped quickly and at low cost with modern Web mining tools, our findings may point to a new and readily applicable approach for the efficient and effective identification of lead users in real-life projects, an aspect that is usually emphasized as the most crucial activity in lead user projects. (authors' abstract
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