Re-Establishment of the Giant Canada Goose in Iowa

Giant Canada geese (Branta canadensis maxima) were common nesters in Iowa before 1900 but were exterminated through overexploitation about that time. Recent efforts by the Iowa Conservation Commission to re-establish these birds have been successful. By providing protection and nesting areas this flock has been increased from a few pair in 1964 to 800-1,000 birds in 1970. The birds have adapted to the surrounding habitat and established a migration tradition. The goal is to increase the flock to 7,000 birds

Generational Equity, Generational Interdependence, and the Framing of the Debate Over Social Security Reform

This article analyzes the differences between the generational equity and generational interdependence conceptual packages used to frame arguments in the debate over policies such as Social Security reform. It begins with a history of the generational equity debate. This is followed by an analysis of the assumptions, values, and beliefs that inform each of these two ideological frames. It presents an analysis of why the generational equity frame has dominated the debate and highlights some of the limitations of this perspective

Two-fluid solutions for Langmuir probes in collisionless and isothermal plasma, over all space and bias potential

This paper presents solutions for the classical one-dimensional (1D radial and Cartesian) problem of Langmuir probes in a collisionless, isothermal plasma. The method is based on two-fluid equations derived from the first two moments of Vlasov's equation. In contrast to commonly used approximations, electron inertia and ion temperature are not neglected so that the fluid equations are symmetric in terms of electrons and ions. The fluid equations are reduced analytically so that the electric potential is the only remaining spatial function, which is numerically determined using Poisson's equation. The single radial solution applies continuously over the whole region from the probe up to the unperturbed plasma, in contrast to theories which separate the probe boundary region into a charged sheath and a quasi-neutral pre-sheath, and is valid for all values of probe bias potential. Current-voltage characteristics are computed for cylindrical and spherical probes, which exhibit non-saturation of the ion and electron currents. The 1D Cartesian case is also analysed, and the Bohm criterion is recovered only in the limit of large radius probes. Published by AIP Publishing

Racial Identity and the Development of Body Image Issues among African American Adolescent Girls

As readers, children with dyslexia are vulnerable to becoming academically, socially, and emotionally detached from education. Traditional educational practices tend to use quantitative measures to diagnose children to better serve their needs and researchers, who study students with special needs often focus on a deficit model that quantify just how far a child is from the norm. This practice, while full of good intentions, often creates emotional scars and feelings of inferiority in a child. This reductionist view of a disability is most likely different from the lived experience of the person with the disability. To get a complete picture, we must use qualitative methods to reveal children’s words, their interactions, and the entire context within which their disability is nested. In this study, I use qualitative methods to unpack the educational experiences of a group of students with dyslexia. Data were gathered from four sources: interviews with students and teachers, field notes, and journal entries. The words of the participants are presented to convey the emotional impact that a reading disability brings and to remind educators and researchers that quantitative methods do not always provide a complete picture of a child’s experience in school

Input silane concentration effect on the a-Si:H to uc-Si:H transition width

In this work the microstructure transition width from amorphous to microcrystalline silicon is discussed. It is shown that the width of the transition depends on the input silane concentration level and indirectly on the silane depletion level. The higher the input silane concentration and depletion, the wider the transition. Experimental results are then compared to an analytical model and good agreement is obtained with a semi-empirical approach that takes into account the e®ect of the silane density in the plasma on the electron density

Study of the microstructure transition width from amorphous to microcrystalline silicon as a function of the input silane concentration

Amorphous and microcrystalline silicon have been proven to be very interesting for low cost thin film photovoltaic devices. Usually these two materials are deposited using the same large area plasma-enhanced chemical vapor deposition reactors from silane and hydrogen gases. The transition from amorphous deposition regime to microcrystalline deposition regime is generally done by reducing the silane concentration in the input gas flow and the optimum deposition parameters to achieve high performance device stands just at the transition between the two microstructures. In the present work, a study of the transition width from amorphous to microcrystalline silicon is presented as a function of the input silane concentration. It is shown that the higher the input silane concentration, the wider is the microstructure transition. As a consequence, the process is less sensitive to fluctuations of the silane concentration when silane concentrations higher than 10 % are used and better uniformity and reproducibility can be then achieved