On negative dispersion without absorption in bichromatically driven two-level systems

Abstract

The possibility of obtaining strong negative dispersion without absorption in the central resonance structure of the spectrum of a bichromatically driven two-level system is investigated. A nonlinear analysis is performed using the technique of continued fractions with respect to the dressedstate basis of a strong pumping laser. We discuss the transition between the two regimes of the monochromatic driving case with a weak probing laser and of nearly equally strong lasers in terms of the contributions from coherences and populations of these dressed states. In contrast with the strong dependence of the Rabi side bands on probe field intensity, we find a remarkable stability of the negative dispersion in the central resonance structure.     

Diurnal cortisol secretion and 2-year changes in older adults' physical symptoms: The moderating roles of negative affect and sleep.

Objective: This study examined whether the association between cortisol secretion and changes in physical health symptoms would depend on other factors in a person's life. The authors expected that physical health effects would emerge particularly when cortisol disturbances co-occur in the context of high levels of trait negative affect or poor sleep. Design: Physical symptoms, diurnal cortisol secretion, affective tendencies, and sleep efficiency were assessed in a 2-yr longitudinal study of 184 older adults. Main Outcome Measure: Two-year changes in physical symptoms. Results: High cortisol levels were associated with increases in physical symptoms, but only among participants who experienced high negative affect and poor sleep. Conclusion: Elevated levels of cortisol secretion contribute to older adults' physical symptoms if they co-occur in the context of other emotional and behavioral problems. By contrast, cortisol disturbances may not influence physical symptoms among people who are emotionally well or engage in efficient sleep behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An impedance-based predictive control strategy for the state-of-health of PEM fuel cell stacks

This work presents a control strategy for PEM fuel cell systems based on simultaneous impedance measurements on single cells. This control strategy distinguishes between flooding and drying of the cells in a stack and helps to run the stack at an optimal operating point. In the presented experiments, it has been found that impedance measurements can detect flooding phenomena in single cells minutes before they can be seen in related polarisation curves. It is shown that impedance measurements at two specific frequencies, one high and one low frequency impedance, are sufficient to predict voltage drops caused by flooding and drying. In flooding mode, the imaginary part of the low frequency impedance changes while the high frequency impedance remains stable and vice versa in drying mode. This technique reduces measuring time compared to the measurement of whole impedance spectra, without losing important information for the control of the system.     

Influence of nonionic emulsifiers on the properties of vinyl acetate/VeoVa10 and vinyl acetate/ethylene emulsions and paints

This paper presents results on the influence of the nonionic surfactant on the properties of vinyl acetate/VeoVa10^® and vinyl acetate/ethylene emulsions and paints made thereof. Emulsions were prepared in which the concentration of the nonionic surfactant and its degree of ethoxylation were varied. An increase of the nonionic emulsifier concentration and of the length of the ethylene oxide chain leads to dispersions with smaller particles and higher viscosities. Using these emulsions as binders in high pigmented paints, it was observed that the pigment binding capacity of the interior paints goes through a maximum which is located at a emulsifier concentration of about 2–3% and at a degree of ethoxylation of 17–28 mol ethylene oxide (EO). In (semi-) gloss paints, the gloss of the paint films improves with an increase of the emulsifier concentration and reaches a constant value at around 4% or a degree of ethoxylation of ca. 17 EO-moieties per molecule. The blocking of the films shows a drastic increase at a concentration above 4% and at a chain length of greater than 17 EO-moieties.     

Process Deviations and Spot Defects: Two Aspects of Test and Test Development for Mixed-Signal Circuits

By their nature, mixed-signal circuits have to be tested for both structural integrity and parametric performance. For the example of data converters we review test pattern selection strategies geared towards structural and performance testing. We introduce a novel test pattern selection strategy that merges both objectives, and by that we achieve a significant reduction in the size of the set of test patterns applied on the production line.     

Architecture Concepts for Multimedia Signal Processing

Architectural concepts are presented aimed at future multimedia processing schemes. Starting from an analysis of current and future multimedia applications, specific computational requirements are derived. It will be shown that multimedia applications benefit from an exhaustive and flexible exploitation of parallelism. Three architectural concepts—reconfigurable computing, simultaneous multithreading, and associative controlling—are presented, and their potential to increase further the performance on future multimedia applications is investigated.     

Bulk properties of pressure-induced superconductivity in EuMo6S8

Characteristics of superconductivity induced by pressureP in EuMo₆S₈ have been investigated by dc magnetization and heat capacity measurements under nearly hydrostatic pressure. No Meissner effect was detected at the superconducting transition, in agreement with previous results, but a discontinuity in the heat capacity data demonstrates the bulk nature of the superconducting state forP≳ 13 kbar. An analysis of the heat capacity data yields a value for this discontinuity comparable to that expected from the BCS theory. In addition, heat capacity measurement forP=11 kbar reveal a feature arising from the structural transition responsible for the absence of superconductivity whenP<13 kbar in EuMo₆S₈.     

Age cohort effects on unemployment in the USA: Evidence from the regional level

Since the early 1970s, it was argued that shifts from relatively smaller to larger youth cohorts in the labor force raise the unemployment rate. In contrast, using US state-level data, two studies come to a contrary conclusion. I provide a theoretical framework for local labor markets that considers age cohort differences in labor market characteristics. Using a spatial panel data model and US county-level data (2000–2014), the estimates provide strong evidence that aging of the working-age population reduces overall unemployment by almost 1 percentage point. Long-run effects that consider local feedbacks are even larger.     

New,Non‐quinone Fluorogeldanamycin Derivatives Strongly Inhibit Hsp90

Streptomyces hygroscopicus is a natural producer of geldanamycin. Mutasynthetic supplementation of an AHBA‐blocked mutant with all possible monofluoro 3‐aminobenzoic acids provided new fluorogeldanamycins. These showed strong antiproliferative activity and inhibitory effects on human heat shock protein Hsp90. Binding to Hsp90 in the low nanomolar range was determined from molecular modelling, AFM analysis and by calorimetric studies.