33 research outputs found
Reconstruction of {\AA}ngstr{\o}m resolution exit-waves by the application of drift-corrected phase-shifting off-axis electron holography
Phase-shifting electron holography is an excellent method to reveal electron
wave phase information with very high phase sensitivity over a large range of
spatial frequencies. It circumvents the limiting trade-off between fringe
spacing and visibility of standard off-axis holography. Previous
implementations have been limited by the independent drift of biprism and
sample. We demonstrate here an advanced drift correction scheme for the
hologram series that allow to obtain reliable phase information at the 1 {\AA}
information limit of the used Titan 80-300 kV environmental transmission
electron microscope using a single biprism at moderate voltage of 250 V. The
obtained phase and amplitude information is validated at a thin Pt sample by
use of multislice image simulation with the frozen lattice approximation and
shows excellent agreement. The presented method drastically reduces the
hardware requirements and thus allows to achieve high resolution in off-axis
holography in various instruments including those for in-situ applications. A
software implementation for the acquisition, calibration and reconstruction is
provided
Seebeck Effect in Magnetic Tunnel Junctions
Creating temperature gradients in magnetic nanostructures has resulted in a
new research direction, i.e., the combination of magneto- and thermoelectric
effects. Here, we demonstrate the observation of one important effect of this
class: the magneto-Seebeck effect. It is observed when a magnetic configuration
changes the charge based Seebeck coefficient. In particular, the Seebeck
coefficient changes during the transition from a parallel to an antiparallel
magnetic configuration in a tunnel junction. In that respect, it is the analog
to the tunneling magnetoresistance. The Seebeck coefficients in parallel and
antiparallel configuration are in the order of the voltages known from the
charge-Seebeck effect. The size and sign of the effect can be controlled by the
composition of the electrodes' atomic layers adjacent to the barrier and the
temperature. Experimentally, we realized 8.8 % magneto-Seebeck effect, which
results from a voltage change of about -8.7 {\mu}V/K from the antiparallel to
the parallel direction close to the predicted value of -12.1 {\mu}V/K.Comment: 16 pages, 7 figures, 2 table
Predictors of mental health in female teachers
Objective: Teaching profession is characterised by an above-average rate of psychosomatic and mental health impairment due to work-related stress. The aim of the study was to identify predictors of mental health in female teachers. Material and Methods: A sample of 630 female teachers (average age 47±7 years) participated in a screening diagnostic inventory. Mental health was surveyed with the General Health Questionnaire GHQ-12. The following parameters were measured: specific work conditions (teacher-specific occupational history), scales of the Effort-Reward-Imbalance (ERI) Questionnaire as well as cardiovascular risk factors, physical complaints (BFB) and personal factors such as inability to recover (FABA), sense of coherence (SOC) and health behaviour. Results: First, mentally fit (MH+) and mentally impaired teachers (MH-) were differentiated based on the GHQ-12 sum score (MH+: < 5; MH-: ≥ 5); 18% of the teachers showed evidence of mental impairment. There were no differences concerning work-related and cardiovascular risk factors as well as health behaviour between MH+ and MH-. Binary logistic regressions identified 4 predictors that showed a significant effect on mental health. The effort-reward-ratio proved to be the most relevant predictor, while physical complaints as well as inability to recover and sense of coherence were identified as advanced predictors (explanation of variance: 23%). Conclusion: Contrary to the expectations, classic work-related factors can hardly contribute to the explanation of mental health. Additionally, cardiovascular risk factors and health behaviour have no relevant influence. However, effort-reward-ratio, physical complaints and personal factors are of considerable influence on mental health in teachers. These relevant predictors should become a part of preventive arrangements for the conservation of teachers' health in the future
Autopoiesis, Biological Autonomy and the Process View of Life
In recent years, an increasing number of theoretical biologists and philosophers of biology have been opposing reductionist research agendas by appealing to the concept of biological autonomy which draws on the older concept of autopoiesis. In my paper, I shall investigate some of the ontological implications of this approach. The emphasis on autonomy and autopoiesis, together with the associated idea of organisational closure, might evoke the impression that organisms are to be categorised ontologically as substances: ontologically independent, well-individuated, discrete particulars. However, I shall argue that this is mistaken. Autopoiesis and biological autonomy, properly understood, require a rigorous commitment to a process ontological view of life