Oxygen-vacancy-mediated Negative Differential Resistance in La and Mg co-substituted BiFeO3 Thin Film

The conductive characteristics of Bi0.9La0.1Fe0.96Mg0.04O3(BLFM) thin film are investigated at various temperatures and a negative differential resistance (NDR) is observed in the thin film, where a leakage current peak occurs upon application of a downward electric field above 80 oC. The origin of the NDR behavior is shown to be related to the ionic defect of oxygen vacancies (VO..) present in the film. On the basis of analyzing the leakage mechanism and surface potential behavior, the NDR behavior can be understood by considering the competition between the polarized distribution and neutralization of VO..

Magnetohydrodynamic Model of Equatorial Plasma Torus in Planetary Nebulae

Some basic structures in planetary nebulae are modeled as self-organized magnetohydrodynamic (MHD) plasma configurations with radial flow. These configurations are described by time self-similar dynamics, where space and time dependences of each physical variable are in separable form. Axisymmetric toroidal MHD plasma configuration is solved under the gravitational field of a central star of mass $M$. With an azimuthal magnetic field, this self-similar MHD model provides an equatorial structure in the form of an axisymmetric torus with nested and closed toroidal magnetic field lines. In the absence of an azimuthal magnetic field, this formulation models the basic features of bipolar planetary nebulae. The evolution function, which accounts for the time evolution of the system, has a bounded and an unbounded evolution track governed respectively by a negative and positive energy density constant $H$.Comment: 14 figure

The mental health treatment gap in South Sudan

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The In Between Landscapes Of Transformation In Ted Kooser\u27s Weather Central

Etude, which launches Weather Central, Ted Kooser\u27s most recent full-length collection of poems, is in many ways typical of the poet\u27s work. The poem is what it professes to be: an etude, a study, a preview of all the poems that are to follow. It also defines the major poetic devices or characteristics that will be important throughout the 1994 volume: direct, plain-spoken language; use of interior and exterior landscape{s); and explicit metaphor that particularizes the poet\u27s life. Many of us who make our home on the plains recognize the Great Blue Heron in the cattails, the bubbles along the water\u27s surface, the blue suit of the everyday job. The poet\u27s guiding metaphor, Great Blue Heron/loverartist, is one we can appreciate, perhaps even participate in, as the bird eases ahead in our memory as well as on the printed page before us. That Kooser\u27s poetry is frequently classified as regional comes as no surprise. Critics throughout the poet\u27s career have pointed to his phenomenology of the plains in and around Lincoln, Nebraska, where he has lived since 1963. Kooser\u27s work, according to Peter Stitt, grows directly out of the life he leads as a more or less average citizen of a more or less average small city set nearly at the center of the United States. David Baker, reviewing for Poetry, sees Weather Central as part of Kooser\u27s larger project, the creation in poetry of a distinctly Midwestern social text. Born in Ames, Iowa, in 1939, Kooser\u27s roots are in the Midwest. He received his B.S. in English education from Iowa State University and then moved to the Lincoln area to work on his M.A. in English, which he received from the University of Nebraska in 1968. Although he has taught poetry writing from time to time and has managed his own press for many years, Kooser has earned his living in a nonacademic, nonliterary environment. Only this year has Kooser retired from Lincoln Benefit Life Company, where he was vice president of marketing. In his close attention to plains life, Kooser can be placed within the tradition of William Carlos Williams. However, Kooser, like Williams before him, suggests that although art is rooted in the local, it need not remain only there. Indeed, Kooser\u27s preoccupation is with mutuality: both the particular and the universal are among his central poetic concerns. As we shall see, an understanding of the way Kooser makes mutuality manifest is crucial to the explication of his poetry. This in turn will lead us to a fuller appreciation of the scope of Kooser\u27s work and to a reassessment of his place among contemporary American writers