3,188 research outputs found

    Hitler's 'National Community': Society and Culture in Nazi Germany Second Edition

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    This book examines Hitler's attempts to create a 'national community'. It examines men, women, the family, the churches and religion. It examines those groups excluded from the 'national community' and it analyses the impact of the Nazi government on German culture

    A microscopic view of the yielding transition in concentrated emulsions

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    We use a custom shear cell coupled to an optical microscope to investigate at the particle level the yielding transition in concentrated emulsions subjected to an oscillatory shear deformation. By performing experiments lasting thousands of cycles on samples at several volume fractions and for a variety of applied strain amplitudes, we obtain a comprehensive, microscopic picture of the yielding transition. We find that irreversible particle motion sharply increases beyond a volume-fraction dependent critical strain, which is found to be in close agreement with the strain beyond which the stress-strain relation probed in rheology experiments significantly departs from linearity. The shear-induced dynamics are very heterogenous: quiescent particles coexist with two distinct populations of mobile and `supermobile' particles. Dynamic activity exhibits spatial and temporal correlations, with rearrangements events organized in bursts of motion affecting localized regions of the sample. Analogies with other sheared soft materials and with recent work on the transition to irreversibility in sheared complex fluids are briefly discussed.Comment: 11 pages, 10 figures. Submitted to Soft Matte

    Continued development of a detailed model of arc discharge dynamics

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    Using a previously developed set of codes (SEMC, CASCAD, ACORN), a parametric study was performed to quantify the parameters which describe the development of a single electron indicated avalanche into a negative tip streamer. The electron distribution function in Teflon is presented for values of the electric field in the range of four-hundred million volts/meter to four billon volts/meter. A formulation of the scattering parameters is developed which shows that the transport can be represented by three independent variables. The distribution of ionization sites is used to indicate an avalanche. The self consistent evolution of the avalanche is computed over the parameter range of scattering set

    Germany

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    By investigating how laws, myths, national aspirations, and global relations have recast and, at times, distorted the key purposes of education, this pathbreaking book sheds light on the role of ignorance in shaping ideas, public opinion, ..

    Modelling spectral line profiles of wind-wind shock emissions from massive binary systems

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    One of the most intriguing spectral features of WR binary stars is the presence of time-dependent line profiles. Long term observations of several systems revealed the periodicity of this variability, synchronized with the orbital movement. Several partially successful models have been proposed to reproduce the observed data. The most promising assume that the origin of the emission is the wind-wind interaction zone. In this scenario, two high velocity and dense winds produce a strong shock layer, responsible for most of the X-rays observed from these systems. As the secondary star moves along its orbital path, the shock region of conical shape, changes its position with relation to the line of sight. As a consequence, the stream measured Doppler shift presents time variations resulting in position changes of the spectral line. In our work, we present an alternative model, introducing turbulence in the shock layer to account for the line broadening and opacity effects for the asymmetry in the line profiles. We showed that the gas turbulence avoids the need of an unnaturally large contact layer thickness to reproduce line broadening. Also, we demonstrated that if the emission from the opposing cone surface is absorbed, the result is a single peaked profile. This result fully satisfies the recent data obtained from massive binary systems, and can help on the determination of both winds and orbital parameters. We successfully applied this model to the Br22 system and determined its orbital parameters.Comment: To appear in the MNRA

    Parents’ Perception of Overweight in Relation to Child Mood and Disordered Eating

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    Parental perception of their child’s weight may impact child’s psychological functioning; however, there is a dearth of literature examining this relationship. Data suggest that parental concern with child’s overweight may be related to child distress and/or disordered eating. Yet, it is unknown if parents’ perception of teens’ overweight relates to child functioning. We examined 113 adolescent (12-17y; 14.4 ± 1.6) boys and girls (53% girls) with overweight or obesity (BMIz 2.0 ± .45) and their parents. Youth self-identified as 53% Caucasian or White, 27% Black or African American, 3.5% Asian, and 16.5% multiple races, unknown, or other. Parents reported on their perception of their child’s overweight as either “somewhat/sometimes true” and “very/often true.” Teens reported on their symptoms of anxiety and depression and whether they had experienced loss-of-control eating in the past month. T-tests and Chi Square analyses were used to analyze child factors based on parent perceptions. Compared to parents who reported “somewhat/sometimes true” (n = 51), parents who reported “very/often true” (n = 62), had children with significantly higher anxiety (p = .048) and higher likelihood of reporting loss-of-control eating in the past month (p = .039). There were no differences in symptoms of depression. Including sex, race, and BMIz as covariates did not alter findings. In summary, youth whose parents perceive their children as more definitively overweight are more likely to report symptoms of anxiety and disordered eating. Further data are needed to determine if parental perception is related to their adolescent child’s overall well-being

    Multispeckle diffusing-wave spectroscopy: a tool to study slow relaxation and time-dependent dynamics

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    A multispeckle technique for efficiently measuring correctly ensemble-averaged intensity autocorrelation functions of scattered light from non-ergodic and/or non-stationary systems is described. The method employs a CCD camera as a multispeckle light detector and a computer-based correlator, and permits the simultaneous calculation of up to 500 correlation functions, where each correlation function is started at a different time. The correlation functions are calculated in real time and are referenced to a unique starting time. The multispeckle nature of the CCD camera detector means that a true ensemble average is calculated; no time averaging is necessary. The technique thus provides a "snapshot" of the dynamics, making it particularly useful for non-stationary systems where the dynamics are changing with time. Delay times spanning the range from 1 ms to 1000 s are readily achieved with this method. The technique is demonstrated in the multiple scattering limit where diffusing-wave spectroscopy theory applies. The technique can also be combined with a recently-developed two-cell technique that can measure faster decay times. The combined technique can measure delay times from 10 ns to 1000 s. The method is peculiarly well suited for studying aging processes in soft glassy materials, which exhibit both short and long relaxation times, non-ergodic dynamics, and slowly-evolving transient behavior.Comment: 11 pages 13 figures Accepted in Review of Scientific Instrument (june 02

    First principles numerical model of avalanche-induced arc discharges in electron-irradiated dielectrics

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    The model consists of four phases: single electron dynamics, single electron avalanche, negative streamer development, and tree formation. Numerical algorithms and computer code implementations are presented for the first three phases. An approach to developing a code description of fourth phase is discussed. Numerical results are presented for a crude material model of Teflon
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