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

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

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

Two-fluid plasma model for radial Langmuir probes as a converging nozzle with sonic choked flow, and sonic passage to supersonic flow

Using the Lambert function, Guittienne et al. [Phys. Plasmas 25, 093519 (2018)] derived two-fluid solutions for radial Langmuir probes in collisionless and isothermal plasma. In this Brief Communication, we point out the close analogy with classical compressible fluid dynamics, where the simultaneous flows of the ion and electron fluids experience opposite electrostatic body forces in the inward radial flow of the plasma, which behaves as a converging nozzle. Hence, the assumed boundary condition of sonic flow of the repelled species at the probe is explained as choked flow. The sonic passage from subsonic to supersonic flow of the attracted species at the sonic radius is also interpreted using classical fluid dynamics. Moreover, the Lambert function can provide a general solution for one-dimensional, isothermal compressible fluids, with several applications