Zum biochemischen Wirkungsmechanismus des adrenocorticotropen Hormons

Es wird eine Übersicht über zwei Hypothesen und die dazugehörigen Befunde zum Wirkungsmechanismus des adrenocorticotropen Hormons gegeben: 1. Der Gehalt der Nebenniere an cyclischem Adenosinmonophosphat wird durch ACTH erhöht, die stimulierende Wirkung des Hormons auf die Corticoidsynthese wird durch cyclisches Adenosinmonophosphat imitiert. Die Beschleunigung der Corticoidsynthese dürfte allerdings nicht durch eine Aktivierung der Phosphorylase in der Nebenniere erfolgen. 2. Befunde zum biochemischen Mechanismus der Stimulation der Proteinsynthese in der Nebenniere durch ACTH werden referiert. Die Intaktheit der Proteinsynthese der Nebenniere scheint für den steroidogenen Effekt des ACTH Voraussetzung zu sein.Two current hypotheses on the mechanism of action of ACTH are reviewed: 1. The content of cyclic 3,5-adenosine monophosphate of the adrenals is increased by ACTH, and cyclic AMP or ACTH enhance corticoid synthesis. However, stimulation of corticoid synthesis presumably is not mediated by activation of adrenal phosphorylase. 2. Experiments dealing with the biochemical mechanism of the stimulation of adrenal protein synthesis are reviewed. The integrity of the adrenal protein synthesis appears to be necessary for the enhancement of corticoid synthesis by ACTH

Improving the Efficiency of Physical Examination Services

The objective of our project was to improve the efficiency of the physical examination screening service of a large hospital system. We began with a detailed simulation model to explore the relationships between four performance measures and three decision factors. We then attempted to identify the optimal physician inquiry starting time by solving a goal-programming problem, where the objective function includes multiple goals. One of our simulation results shows that the proposed optimal physician inquiry starting time decreased patient wait times by 50% without increasing overall physician utilization

Excitonic recombination dynamics in shallow quantum wells

We report a comprehensive study of carrier-recombination dynamics in shallow AlxGa1-xAs/GaAs quantum wells. At low crystal temperature (2 K), the excitonic radiative recombination time is shown to be strongly enhanced in shallow quantum wells with x>0.01, consistently with a model that takes into account the thermal equilibrium between the three-dimensional exciton gas of the barrier and the two-dimensional exciton gas, which are closer in energy as x decreases. Furthermore, we demonstrate the existence of a thermally activated escape mechanism due to the low effective barrier height in these structures. The nonradiative recombination is shown to dominate the carrier dynamics for temperatures as low as 10 K for x≈0.01. Our experimental observations are analyzed using three different variational exciton calculations. In particular, we study the crossover from the two-dimensional to the three-dimensional behavior of the exciton, which occurs for x as low as 0.01 and affects mainly the oscillator strength, whereas the transition energies in shallow quantum wells can be calculated, to a large extent, using the same approximations as for conventional quantum wells. The peculiar behavior of the oscillator strength at the crossover to the weak confinement regime is obtained by expansion in a large basis

Isotopic investigations of Chinese ceramics

This chapter provides insights into Chinese ceramic technologies of both bodies and glazes as well as provenance by using isotopes applied to a number of case studies. The use of Sr isotopes to investigate Chinese high-fired Celadon wares and blue-and-white Jingdezhen porcelain (Jiangxi province) has revealed a clear distinction associated with the fluxes used in the glazes: plant ash in celadons and limestone in Jingdezhen glazes, something that is not clear from major element analysis. Furthermore, the technique is able to suggest by implication the nature of the silica source used in the glazes—normally weathered granitic rocks or metamorphic rocks (porcelain stone) which also contains Sr. This leads to an isotopic mixing line of the 2 Sr-rich components and is proof that 2 Sr-rich components were mixed in the manufacture of limestone glaze. This is not the case for plant ash glazes. Eventually, the technique may be used in provenance studies. Like Sr isotope analysis, lead isotope analysis relies on there being a lack of or a minimal change in the isotope ratios when the raw materials are heated. Lead isotope analysis links the use of lead in glazes to the original metal ore and if a kiln uses a distinctive lead source in its glazes, it can provide a provenance for the pottery. This has been very successful in distinguishing Chinese Tang sancai wares made in the Huangye, Huangbao, Liquanfang and Qionglai kilns