296 research outputs found
Outside board memberships of CEOs: Expertise or entrenchment?
We investigate whether outside board memberships of CEOs signal expertise or entrenchment. The analysis is based on panel data of the largest German companies covering the period from 1996 to 2008. Supporting the entrenchment hypothesis, our analysis reveals that firms having a CEO with one or more outside mandates suffer from significantly weaker firm performance compared with firms having a CEO without any outside board mandates. Moreover, disciplinary CEO turnovers become less likely and turnover-performance sensitivity declines with rising board memberships of the top manager. We conclude that outside mandates enhance managerial power at the expense of the home firm's shareholders. --Corporate Governance,Entrenchment,Outside Board Memberships,CEO turnover
Stress and eating behavior
How stress, the stress response, and the adaptation of the stress response influence our eating behavior is a central question in brain research and medicine. In this report, we highlight recent advances showing the close links between eating behavior, the stress system, and neurometabolism
The effect of wavefront aberrations in atom interferometry
Wavefront aberrations are one of the largest uncertainty factors in present
atom interferometers. We present a detailed numerical and experimental analysis
of this effect based on measured aberrations from optical windows. By placing
windows into the Raman beam path of our atomic gravimeter, we verify for the
first time the induced bias in very good agreement with theory. Our method can
be used to reduce the uncertainty in atomic gravimeters by one order of
magnitude resulting in an error of less than and it is
suitable in a wide variety of atom interferometers with thermal or ultra cold
atoms. We discuss the limitations of our method, potential improvements and its
role in future generation experiments.Comment: Applied Physics B, 201
Build-Ups in the Supply Chain of the Brain: on the Neuroenergetic Cause of Obesity and Type 2 Diabetes Mellitus
Obesity and type 2 diabetes have become the major health problems in many industrialized countries. A few theoretical frameworks have been set up to derive the possible determinative cause of obesity. One concept views that food availability determines food intake, i.e. that obesity is the result of an external energy “push” into the body. Another one views that the energy milieu within the human organism determines food intake, i.e. that obesity is due to an excessive “pull” from inside the organism. Here we present the unconventional concept that a healthy organism is maintained by a “competent brain-pull” which serves systemic homeostasis, and that the underlying cause of obesity is “incompetent brain-pull”, i.e. that the brain is unable to properly demand glucose from the body. We describe the energy fluxes from the environment, through the body, towards the brain with a mathematical “supply chain” model and test whether its predictions fit medical and experimental data sets from our and other research groups. In this way, we show data-based support of our hypothesis, which states that under conditions of food abundance incompetent brain-pull will lead to build-ups in the supply chain culminating in obesity and type 2 diabetes. In the same way, we demonstrate support of the related hypothesis, which states that under conditions of food deprivation a competent brain-pull mechanism is indispensable for the continuance of the brain´s high energy level. In conclusion, we took the viewpoint of integrative physiology and provided evidence for the necessity of brain-pull mechanisms for the benefit of health. Along these lines, our work supports recent molecular findings from the field of neuroenergetics and continues the work on the “Selfish Brain” theory dealing with the maintenance of the cerebral and peripheral energy homeostasis
A portable laser system for high precision atom interferometry experiments
We present a modular rack-mounted laser system for the cooling and
manipulation of neutral rubidium atoms which has been developed for a portable
gravimeter based on atom interferometry that will be capable of performing high
precision gravity measurements directly at sites of geophysical interest. This
laser system is constructed in a compact and mobile design so that it can be
transported to different locations, yet it still offers improvements over many
conventional laboratory-based laser systems. Our system is contained in a
standard 19" rack and emits light at five different frequencies simultaneously
on up to 12 fibre ports at a total output power of 800 mW. These frequencies
can be changed and switched between ports in less than a microsecond. The setup
includes two phase-locked diode lasers with a phase noise spectral density of
less than 1 \mu rad/sqrt(Hz) in the frequency range in which our gravimeter is
most sensitive to noise. We characterize this laser system and evaluate the
performance limits it imposes on an interferometer.Comment: 8 pages, 11 figures; The final publication is available at
http://www.springerlink.co
Magnetic trapping of buffer-gas cooled chromium atoms and prospects for the extension to paramagnetic molecules
We report the successful buffer-gas cooling and magnetic trapping of chromium
atoms with densities exceeding atoms per cm at a temperature of
350 mK for the trapped sample. The possibilities to extend the method to
buffer-gas cool and magnetically trap molecules are discussed. To minimize the
most important loss mechanism in magnetic trapping, molecules with a small
spin-spin interaction and a large rotational constant are preferred. Both the
CrH ( ground state) and MnH () radicals appear to be
suitable systems for future experiments.Comment: 9 pages, 4 Figure
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