3,206 research outputs found
Hitler's 'National Community': Society and Culture in Nazi Germany Second Edition
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
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
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
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
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
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
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
An adaptable method using human mixed tissue ratiometric controls for benchmarking performance on gene expression microarrays in clinical laboratories
<p>Abstract</p> <p>Background</p> <p>Molecular biomarkers that are based on mRNA transcripts are being developed for the diagnosis and treatment of a number of diseases. DNA microarrays are one of the primary technologies being used to develop classifiers from gene expression data for clinically relevant outcomes. Microarray assays are highly multiplexed measures of comparative gene expression but have a limited dynamic range of measurement and show compression in fold change detection. To increase the clinical utility of microarrays, assay controls are needed that benchmark performance using metrics that are relevant to the analysis of genomic data generated with biological samples.</p> <p>Results</p> <p>Ratiometric controls were prepared from commercial sources of high quality RNA from human tissues with distinctly different expression profiles and mixed in defined ratios. The samples were processed using six different target labeling protocols and replicate datasets were generated on high density gene expression microarrays. The area under the curve from receiver operating characteristic plots was calculated to measure diagnostic performance. The reliable region of the dynamic range was derived from log<sub>2 </sub>ratio deviation plots made for each dataset. Small but statistically significant differences in diagnostic performance were observed between standardized assays available from the array manufacturer and alternative methods for target generation. Assay performance using the reliable range of comparative measurement as a metric was improved by adjusting sample hybridization conditions for one commercial kit.</p> <p>Conclusions</p> <p>Process improvement in microarray assay performance was demonstrated using samples prepared from commercially available materials and two metrics - diagnostic performance and the reliable range of measurement. These methods have advantages over approaches that use a limited set of external controls or correlations to reference sets, because they provide benchmark values that can be used by clinical laboratories to help optimize protocol conditions and laboratory proficiency with microarray assays.</p
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