Correlations of electromagnetic fields in chaotic cavities

We consider the fluctuations of electromagnetic fields in chaotic microwave cavities. We calculate the transversal and longitudinal correlation function based on a random wave assumption and compare the predictions with measurements on two- and three-dimensional microwave cavities.Comment: Europhys style, 8 pages, 3 figures (included

Contribution of the adrenal gland to the production of androstenedione and testosterone during the first two years of life

Androstenedione and testosterone were measured in whole adrenal glands of 56 previously healthy boys who died suddenly between birth and 2 yr of age. In each adrenal gland, the concentration of androstenedione considerably exceeded that of testosterone. The highest concentrations were found during the first week of life (median, 295 ng/g; range, 98- 320 ng/g). Thereafter, values decreased rapidly until the end of the first year of life (median, 10 ng/g; range, 4.4-22.7 ng/g). Adrenal testosterone concentrations averaged 15% of those of androstenedione in the same gland and similarly decreased until the end of the first year. The decrease of adrenal androgen concentrations paralleled the involution of the fetal adrenal zone. A close correlation existed between the concentration of androstenedione in adrenal tissue and plasma. However, no correlation existed between adrenal and plasma testosterone. When the adrenals and testes of the same infant were compared, there was 10 times more androstenedione in the adrenals than in the testes during the first 2 yr of life. The testes contained more testosterone than the adrenals only during the first 4 months. Thus, in infant boys the adrenals are the main source of androstenedione during the first 2 yr. After the sixth month of life, they also are the main source of testosterone

Testosterone and androstenedione concentrations in human testis and epididymis during the first two years of life

Testosterone and androstenedione were measured in testicular and epididymal tissue of 37 previously healthy infants between 1 and 24 months of age who died suddenly. In half of the patients elevated plasma levels of cortisol and androstenedione suggested preterminal stress. Plasma testosterone levels, however, did not differ from those in healthy infants. Testicular testosterone concentrations were maximal in boys from 1-3 months of age (median, 36.6 ng/g; range, 7-380 ng/g) with peak values similar to those found in pubertal or even adult testes. Thereafter testicular testosterone concentrations decreased and after the age of 6 months all values were below 12.5 ng/g, which corresponds to the low normal range of older prepubertal boys. Plasma testosterone and testicular testosterone correlated significantly (P less than 0.001). On average the testicular concentrations were 36.4 times higher than the corresponding plasma concentrations. Testicular androstenedione was low but correlated significantly with testicular testosterone (P less than 0.001). Epididymal testosterone concentrations were surprisingly high (1-3 months: median, 10.3 ng/g; range, 4-42.7 ng/g) and averaged 30% of the testicular testosterone concentration. Thus, epididymal testosterone concentrations were significantly higher than the circulating plasma testosterone levels, indicating the capacity of the infant epididymis to accumulate androgens. These findings suggest that high local testosterone concentrations during early infancy are important not only for the testis itself but particularly for the developing epididymi

The 14C(n,g) cross section between 10 keV and 1 MeV

The neutron capture cross section of 14C is of relevance for several nucleosynthesis scenarios such as inhomogeneous Big Bang models, neutron induced CNO cycles, and neutrino driven wind models for the r process. The 14C(n,g) reaction is also important for the validation of the Coulomb dissociation method, where the (n,g) cross section can be indirectly obtained via the time-reversed process. So far, the example of 14C is the only case with neutrons where both, direct measurement and indirect Coulomb dissociation, have been applied. Unfortunately, the interpretation is obscured by discrepancies between several experiments and theory. Therefore, we report on new direct measurements of the 14C(n,g) reaction with neutron energies ranging from 20 to 800 keV

Optical properties of (AlxGa1-x)(0.52)In0.48P at the crossover from a direct-gap to an indirect-gap semiconductor

The optical properties and the dynamics of excitons and the electron-hole plasma have been studied in disordered (AlxGa1−x)0.52In0.48P near to the direct-to-indirect band gap crossover. In particular we have investigated three epitaxial layers grown by solid-source molecular beam epitaxy with varying Al content x. Two of them have compositions in the immediate vicinity of the crossover point, the other is assigned to the indirect-gap regime. Both direct and indirect recombination processes contribute to the photon emission from the material. Since the relative importance of the different recombination processes depends strongly on temperature, excitation intensity, and excitation pulse duration, the processes can be identified by changing these parameters. As a result, we can determine the relative alignment of the conduction band minima and the distribution of the electrons among them. At high excitation levels the two crossover samples show stimulated emission at a photon energy of ∼2.29 eV, i.e., in the green spectral range. Using the variable stripe length method, we find an optical gain of up to ∼600 cm−1 at excitation levels of ∼350 kW/cm2.Stimulated emission involves direct recombination. This conclusion is reached from the experiments and from line-shape modeling, including a self-consistent treatment of populations and renormalization of the conduction band minima

Monitoring of tritium purity during long-term circulation in the KATRIN test experiment LOOPINO using laser Raman spectroscopy

The gas circulation loop LOOPINO has been set up and commissioned at Tritium Laboratory Karlsruhe (TLK) to perform Raman measurements of circulating tritium mixtures under conditions similar to the inner loop system of the neutrino-mass experiment KATRIN, which is currently under construction. A custom-made interface is used to connect the tritium containing measurement cell, located inside a glove box, with the Raman setup standing on the outside. A tritium sample (purity > 95%, 20 kPa total pressure) was circulated in LOOPINO for more than three weeks with a total throughput of 770 g of tritium. Compositional changes in the sample and the formation of tritiated and deuterated methanes CT_(4-n)X_n (X=H,D; n=0,1) were observed. Both effects are caused by hydrogen isotope exchange reactions and gas-wall interactions, due to tritium {\beta} decay. A precision of 0.1% was achieved for the monitoring of the T_2 Q_1-branch, which fulfills the requirements for the KATRIN experiment and demonstrates the feasibility of high-precision Raman measurements with tritium inside a glove box

Laboratory robustness validation of a humidity sensor system for the condition monitoring of grease-lubricated components for railway applications

The condition monitoring of the health status of lubricating greases used in axle box bearings can be realized by applying well-established electrical or optical measurement principles. Furthermore, some novel methods have been reported that make use of humidity sensors or of dielectric thermoscopy. One of the most important grease condition parameters is the water content of the lubricating grease, as water can degrade grease to the point that it is no longer able to provide suitable lubrication and can also damage the bearing due to corrosion and cavitation. In this study, a new approach for water detection in lubricated wagon components is presented that is based on commercially available humidity sensors. The core element of this sensor system is a robust humidity sensor mounted in the immediate atmosphere of the grease-lubricated wagon axle bearing. In the case of water intake, the humidity of the gaseous atmosphere above the grease increases and can be detected by the customized sensor concept Humidity Sensor in Axle Bearings (HSAB). As this sensor system has to be sufficiently robust, it must be able to withstand environmental impact factors. The most important of these factors are temperature, relative humidity, and mechanical load, like vibrations and shocks, depending on the relevant railway application. To mimic these field effects under controlled laboratory conditions, the “lab-to-field” approach was set up and employed. Of the utmost importance was the installation of a development environment for the sensors that enabled the transfer of laboratory results to the respective rail field application. As a result, the HSAB system shows promise with respect to enhancing the reliability of railway wagons and decreasing maintenance costs, thereby reducing the downtime of railway wagons significantly.</p

Global versus local billiard level dynamics: The limits of universality

Level dynamics measurements have been performed in a Sinai microwave billiard as a function of a single length, as well as in rectangular billiards with randomly distributed disks as a function of the position of one disk. In the first case the field distribution is changed globally, and velocity distributions and autocorrelation functions are well described by universal functions derived by Simons and Altshuler. In the second case the field distribution is changed locally. Here another type of universal correlations is observed. It can be derived under the assumption that chaotic wave functions may be described by a random superposition of plane waves

Electron correlation vs. stabilization: A two-electron model atom in an intense laser pulse

We study numerically stabilization against ionization of a fully correlated two-electron model atom in an intense laser pulse. We concentrate on two frequency regimes: very high frequency, where the photon energy exceeds both, the ionization potential of the outer {\em and} the inner electron, and an intermediate frequency where, from a ``single active electron''-point of view the outer electron is expected to stabilize but the inner one is not. Our results reveal that correlation reduces stabilization when compared to results from single active electron-calculations. However, despite this destabilizing effect of electron correlation we still observe a decreasing ionization probability within a certain intensity domain in the high-frequency case. We compare our results from the fully correlated simulations with those from simpler, approximate models. This is useful for future work on ``real'' more-than-one electron atoms, not yet accessible to numerical {\em ab initio} methods.Comment: 8 pages, 8 figures in an extra ps-file, submitted to Phys. Rev. A, updated references and shortened introductio

A Randomized, Placebo-Controlled Trial

Objective: To examine whether treatment with epigallocatechin gallate (EGCG) influences progression of brain atrophy, reduces clinical and further radiologic disease activity markers, and is safe in patients with progressive multiple sclerosis (PMS). Methods: We enrolled 61 patients with primary or secondary PMS in a randomized double-blind, parallel-group, phase II trial on oral EGCG (up to 1,200 mg daily) or placebo for 36 months with an optional open-label EGCG treatment extension (OE) of 12-month duration. The primary end point was the rate of brain atrophy, quantified as brain parenchymal fraction (BPF). The secondary end points were radiologic and clinical disease parameters and safety assessments. Results: In our cohort, 30 patients were randomized to EGCG treatment and 31 to placebo. Thirty-eight patients (19 from each group) completed the study. The primary endpoint was not met, as in 36 months the rate of decrease in BPF was 0.0092 +/- 0.0152 in the treatment group and -0.0078 +/- 0.0159 in placebo-treated patients. None of the secondary MRI and clinical end points revealed group differences. Adverse events of EGCG were mostly mild and occurred with a similar incidence in the placebo group. One patient in the EGCG group had to stop treatment due to elevated aminotransferases (>3.5 times above normal limit). Conclusions: In a phase II trial including patients with multiple sclerosis (MS) with progressive disease course, we were unable to demonstrate a treatment effect of EGCG on the primary and secondary radiologic and clinical disease parameters while confirming on overall beneficial safety profile. Clinicaltrial.gov Identifier NCT00799890. Classification of Evidence This phase II trial provides Class II evidence that for patients with PMS, EGCG was safe, well tolerated, and did not significantly reduce the rate of brain atrophy