9,499 research outputs found

    An Illustrated Key to the Pupae of Six Species of \u3ci\u3eHydropsyche\u3c/i\u3e (Trichoptera: Hydropsychidae) Common in Southern Ontario Streams

    Get PDF
    I present a key for the identification of pupae and pupal exuviae of six species of Hydropsyche that are widely distributed throughout northeastern North America and that are particularly abundant in the streams of southern Ontario. Use of the pupal key requires less manipulation of a specimen than either removing larval sclerites from the pupal case or attempting to discern the adult genitalia through the pupal integument

    Discussion of: A statistical analysis of multiple temperature proxies: Are reconstructions of surface temperatures over the last 1000 years reliable?

    Full text link
    Discussion of "A statistical analysis of multiple temperature proxies: Are reconstructions of surface temperatures over the last 1000 years reliable?" by B.B. McShane and A.J. Wyner [arXiv:1104.4002]Comment: Published in at http://dx.doi.org/10.1214/10-AOAS398F the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Use of record-linkage to handle non-response and improve alcohol consumption estimates in health survey data: a study protocol

    Get PDF
    <p>Introduction: Reliable estimates of health-related behaviours, such as levels of alcohol consumption in the population, are required to formulate and evaluate policies. National surveys provide such data; validity depends on generalisability, but this is threatened by declining response levels. Attempts to address bias arising from non-response are typically limited to survey weights based on sociodemographic characteristics, which do not capture differential health and related behaviours within categories. This project aims to explore and address non-response bias in health surveys with a focus on alcohol consumption.</p> <p>Methods and analysis: The Scottish Health Surveys (SHeS) aim to provide estimates representative of the Scottish population living in private households. Survey data of consenting participants (92% of the achieved sample) have been record-linked to routine hospital admission (Scottish Morbidity Records (SMR)) and mortality (from National Records of Scotland (NRS)) data for surveys conducted in 1995, 1998, 2003, 2008, 2009 and 2010 (total adult sample size around 40 000), with maximum follow-up of 16 years. Also available are census information and SMR/NRS data for the general population. Comparisons of alcohol-related mortality and hospital admission rates in the linked SHeS-SMR/NRS with those in the general population will be made. Survey data will be augmented by quantification of differences to refine alcohol consumption estimates through the application of multiple imputation or inverse probability weighting. The resulting corrected estimates of population alcohol consumption will enable superior policy evaluation. An advanced weighting procedure will be developed for wider use.</p> <p>Ethics and dissemination: Ethics approval for SHeS has been given by the National Health Service (NHS) Multi-Centre Research Ethics Committee and use of linked data has been approved by the Privacy Advisory Committee to the Board of NHS National Services Scotland and Registrar General. Funding has been granted by the MRC. The outputs will include four or five public health and statistical methodological international journal and conference papers.</p&gt

    Distributional Effects of Fiscal Consolidation.

    Get PDF
    This paper examines the distributional consequences of public debt reduction achieved through spending cuts. Under the assumption that public goods and transfers are relatively more valuable to the poor, our calculations indicate that the elderly poor stand to lose from such policies. Debt reduction produces short-term deficits and long-term surpluses, and when future surpluses are recycled into higher provision of public goods and transfers, future generations of poor could gain. If future surpluses are recycled through lower labour taxes, working households in the future would be positively affected. We conclude that debt reduction could have positive or negative impacts on vertical equity, yet inter- rather than intra-generational equity is likely to pose the greatest obstacle to fiscal consolidation. Based on majority voting by self-interested households, debt reduction would never occur. Yet, in a formal social welfare analysis, some debt reduction programmes may be deemed beneficial with social discount factors as high as two percent. When we then consider alternative time profiles for debt reduction, we conclude that slower is better.

    Robustness of proxy-based climate field reconstruction methods

    Get PDF
    We present results from continued investigations into the fidelity of covariance-based climate field reconstruction (CFR) approaches used in proxy-based climate reconstruction. Our experiments employ synthetic “pseudoproxy” data derived from simulations of forced climate changes over the past millennium. Using networks of these pseudoproxy data, we investigate the sensitivity of CFR performance to signal-to-noise ratios, the noise spectrum, the spatial sampling of pseudoproxy locations, the statistical representation of predictors used, and the diagnostic used to quantify reconstruction skill. Our results reinforce previous conclusions that CFR methods, correctly implemented and applied to suitable networks of proxy data, should yield reliable reconstructions of past climate histories within estimated uncertainties. Our results also demonstrate the deleterious impact of a linear detrending procedure performed recently in certain CFR studies and illustrate flaws in some previously proposed metrics of reconstruction skill

    Market Structure in the Residential Real Estate Brokerage Market

    Get PDF
    This study provides empirical evidence regarding brokerage firm concentration in a local market multiple listing service setting over the year 1992-1995. To evaluate the level of brokerage firm concentration in this market, Gini Coefficients, Herfindahl-Hirschman Indices and Concentration Ratios for each year of the study period are calculated. Our results indicate that for firms responsible for listing properties, firm concentration has not varied substantially over the four-year study period. However, for those firms that were responsible for actually selling properties, firm concentration has decreased over the study period. This finding tends to indicate that the MLS now provides greater exposure to a wide variety of sales firms, therefore leading to a higher level of competition with a lower level of concentration for selling firms in this local market.

    The geometry of reaction norms yields insights on classical fitness functions for Great Lakes salmon.

    Get PDF
    Life history theory examines how characteristics of organisms, such as age and size at maturity, may vary through natural selection as evolutionary responses that optimize fitness. Here we ask how predictions of age and size at maturity differ for the three classical fitness functions-intrinsic rate of natural increase r, net reproductive rate R0, and reproductive value Vx-for semelparous species. We show that different choices of fitness functions can lead to very different predictions of species behavior. In one's efforts to understand an organism's behavior and to develop effective conservation and management policies, the choice of fitness function matters. The central ingredient of our approach is the maturation reaction norm (MRN), which describes how optimal age and size at maturation vary with growth rate or mortality rate. We develop a practical geometric construction of MRNs that allows us to include different growth functions (linear growth and nonlinear von Bertalanffy growth in length) and develop two-dimensional MRNs useful for quantifying growth-mortality trade-offs. We relate our approach to Beverton-Holt life history invariants and to the Stearns-Koella categorization of MRNs. We conclude with a detailed discussion of life history parameters for Great Lakes Chinook Salmon and demonstrate that age and size at maturity are consistent with predictions using R0 (but not r or Vx) as the underlying fitness function

    Characteristics of Home: Perspectives of Women Who Are Homeless

    Get PDF
    We employed participatory, community-based research methods to explore the perceptions of home among women who are homeless. Twenty women engaged in one or more techniques including qualitative interviews, digital story telling, creative writing, photovoice, and design charrette to characterize their perceptions of home. Analysis of the data revealed themes related to the physical, affective, and external environment. By understanding how participants perceive home and the qualities they deem necessary for home, we can begin to construct home from both a service and design perspective that meets womens needs for stable, safe housing and home, and also gain a better understanding of what is needed to assist women in exiting homelessness and building more sustainable futures for themselves and their families

    Experimental and model constraints on degassing of magma during ascent and eruption.

    No full text
    Surface volcanic gases may reflect volatile budgets of magma and forecast impending eruptions, and their release to the atmosphere may affect climate. The dynamics of magma degassing is complicated, however, by differences in the solubility, partitioning, and diffusion of the various volatiles, all of which can vary with pressure, temperature, and melt composition. To constrain possible gas outputs, we carried out experiments to determine how Cl partitions between water bubbles and silicate melt, and decompression experiments to examine how Cl behaves during closed- and open-system degassing. We incorporate our findings and those from the literature for CO2 and S into a steady, isothermal, and homogeneous flow model to estimate fluxes of gases at the vent from ascending water-rich magma, assuming different scenarios for the onset and development of permeability in bubbly magma. We find that, for given permeability scenarios, total gas fluxes vary with magma flux, but ratios of gas species do not change. The S/Cl and SO2/CO2 ratios do change, however, depending on whether the magma is oxidized or reduced. After magma fragments into a Plinian eruption column gases continue to escape from cooling pumice in the plume, but here the rate of gas release is controlled by diffusion, which varies with temperature. Degassing of pumice and ash was modeled by linking a steady-state plume model, which gives the vertical variation of mean temperature and velocity of particles inside the plume, to a conductive cooling model of pumices, which controls diffusion of Cl, CO2, and S in pumice. We find that gas loss increases with column height (mass flux) and initial temperature, because in both cases pumices cool over a longer time period, allowing more gas to diffuse out of the matrix glass. The amount of gas released also depends on the size distribution of particles in the erupting mixture, with less being released for a finely skewed distribution

    What does STOP-IgAN tell us about how to treat IgA nephropathy?

    Get PDF
    No abstract available
    corecore