6,249 research outputs found

    Mapping functional traits: comparing abundance and presence-absence estimates at large spatial scales

    Get PDF
    Efforts to quantify the composition of biological communities increasingly focus on functional traits. The composition of communities in terms of traits can be summarized in several ways. Ecologists are beginning to map the geographic distribution of trait-based metrics from various sources of data, but the maps have not been tested against independent data. Using data for birds of the Western Hemisphere, we test for the first time the most commonly used method for mapping community trait composition – overlaying range maps, which assumes that the local abundance of a given species is unrelated to the traits in question – and three new methods that as well as the range maps include varying degrees of information about interspecific and geographic variation in abundance. For each method, and for four traits (body mass, generation length, migratory behaviour, diet) we calculated community-weighted mean of trait values, functional richness and functional divergence. The maps based on species ranges and limited abundance data were compared with independent data on community species composition from the American Christmas Bird Count (CBC) scheme coupled with data on traits. The correspondence with observed community composition at the CBC sites was mostly positive (62/73 correlations) but varied widely depending on the metric of community composition and method used (R2: 5.6×10−7 to 0.82, with a median of 0.12). Importantly, the commonly-used range-overlap method resulted in the best fit (21/22 correlations positive; R2: 0.004 to 0.8, with a median of 0.33). Given the paucity of data on the local abundance of species, overlaying range maps appears to be the best available method for estimating patterns of community composition, but the poor fit for some metrics suggests that local abundance data are urgently needed to allow more accurate estimates of the composition of communities

    Toward More Efficient Organic Solar Cells: A Detailed Study of Loss Pathway and Its Impact on Overall Device Performance in Low‐Offset Organic Solar Cells

    Get PDF
    Low-offset organic solar cell systems have attracted great interest since nonfullerene acceptors came into the picture. While numerous studies have focused on the charge generation process in these low-offset systems, only a few studies have focused on the details of each loss channel in the charge generation process and their impact on the overall device performance. Here, several nonfullerene acceptors are blended with the same polymer donor to form a series of low-offset organic solar cell systems where significant variation in device performance is observed. Through detailed analyses of loss pathways, it is found that: i) the donor:acceptor interfaces of PM6:Y6 and PM6:TPT10 are close to the optimum energetic condition, ii) energetics at the donor:acceptor interface are the most important factor to the overall device performance, iii) exciton dissociation yield can be field-dependent owing to the sufficiently small energetic offset at the donor:acceptor interface, and iv) the change in substituents in the terminal group of Y-series acceptors in this work mainly affects energetics at the donor:acceptor interface instead of the interface density in the active layer. In general, this work presents a path toward more efficient organic solar cells

    International Market Segmentation across Consumption and Communication Categories: Identity, Demographics, and Consumer Decisions and Online Habits

    Get PDF
    In this chapter we will discuss the different approaches to market segmentation and selection and explore how the selection process influences the company’s culture, its brand positioning, and how it is impacted upon by the overall marketing and communication strategy and vice versa. Some questions this chapter considers and discusses are: Which segments should firms’ international marketing activities (including financial, human resources, and the firm’s capabilities) focus on? How do multinationals decide if segmentation efforts are effective? Finally, we will explore how organizations1 can monitor and control the various activities and outcomes, in order to ensure sustainable competitive advantage(s) in a highly competitive marketplace and online marketspace

    The Use of Palliative Performance Score in Patients with End-Stage Liver Disease

    Get PDF
    ● Palliative Care services are often underutilized in patients with End-Stage Liver Disease (ESLD) and often only initiated at the end of life ● The Palliative Performance Score (PPS) is an important tool used in Palliative Care to assess functional status ● PPS has five functional dimensions: ambulation, activity level and evidence of disease, self-care, oral intake, and level of consciousness ● The aim of this study is to determine if there is a correlation between Model for End-Stage Liver Disease (MELD) score and PPS in ESLD patients ● MELD is used to predict mortality and to prioritize liver transplant allocation in ESLD patientshttps://jdc.jefferson.edu/medposters/1011/thumbnail.jp

    The peculiar B-type supergiant HD327083

    Full text link
    Coude spectroscopic data of a poorly-studied peculiar supergiant, HD327083, are presented. Halpha and Hbeta line profiles have been fitted employing a non-LTE code adequate for spherically expanding atmospheres. Line fits lead to estimates of physical parameters. These parameters suggest that HD327083 may be close to the Luminous Blue Variable phase but it is also possible that it could be a B[e] Supergiant.Comment: 4 pages, 4 figures, Accepted for publication in A&A Lette
    • …
    corecore