Allgemeine Untersuchungsverfahren und Laboratoriumstechnik

Ohne Zusammenfassung     

Molecular changes during learning: Behavioral strategy: A comment on Gaito and Bonnet.

Discusses J. Gaito and K. Bonnet's (see record 1971-07612-001) recent review which suggests that there is no conclusive evidence linking macromolecular changes to learning and memory. It is contended that current experiments in this field are not properly designed to test the hypothesis that a general macromolecular process underlies learning and memory, since the control group designated "nonlearning" is not achieved with the typical control procedures. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Emotional labor, strain, and performance: Testing reciprocal relationships in a longitudinal panel study.

Models of emotional labor suggest that emotional labor leads to strain and affects job performance. Although the link between emotional labor, strain, and performance has been well documented in cross-sectional field studies, not much is known about the causal direction of relationships between emotional labor, strain, and performance. Goal of the present study was therefore to test the direction of effects in a two-wave longitudinal panel study using a sample of 151 trainee teachers. Longitudinal lagged effects were tested using structural equation modeling. Results revealed that the emotional labor strategy of surface acting led to increases in subsequent strain while deep acting led to increases in job performance. In contrast, there was no indication of reverse causation: Neither strain nor job performance had a significant lagged effect on subsequent surface or deep acting. Overall, results support models of emotional labor suggesting that surface and deep acting causally precede individual and organizational well-being. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stevia – Ein natürliches Sü?ungsmittel mit gesundheitlichem Zusatznutzen?

Eine Besonderheit der natürlichen Sü?stoffe aus Stevia rebaudiana soll ihre vorteilhafte pharmakologische Wirkung sein. In der wissenschaftlichen Literatur wird immer wieder ein Einfluss auf den menschlichen Blutzuckergehalt und den Blutdruck genannt. Dies w?re ein Novum: Ein Sü?ungsmittel mit Heilwirkung.     

Optical transistors for ultrafast processing and transfer of information

The prospects, opportunities, and advantages of the optical transistor for the ultrafast processing and transfer of information in broadband optical communication lines and networks are briefly considered.     

Influence of correlated errors on the estimation of the relaxation time spectrum in dynamic light scattering

An important step in analyzing data from dynamic light scattering is estimating the relaxation time spectrum from the correlation time function. This estimation is frequently done by regularization methods. To obtain good results with this step, the statistical errors of the correlation time function must be taken into account [J. Phys. A 6, 1897 (1973)]. So far error models assuming independent statistical errors have been used in the estimation. We show that results for the relaxation time spectrum are better if correlation between statistical errors is taken into account. There are two possible ways to obtain the error sizes and their correlations. On the one hand, they can be calculated from the correlation time function by use of a model derived by Sch?tzel. On the other hand, they can be computed directly from the time series of the scattered light. Simulations demonstrate that the best results are obtained with the latter method. This method requires, however, storing the time series of the scattered light during the experiment. Therefore a modified experimental setup is needed. Nevertheless the simulations also show improvement in the resulting relaxation time spectra if the error model of Sch?tzel is used. This improvement is confirmed when a lattice with a bimodal sphere size distribution is applied to experimental data.     

Algebraic manipulation of scientific datasets

We investigate algebraic processing strategies for large numeric datasets equipped with a (possibly irregular) grid structure. Such datasets arise, for example, in computational simulations, observation networks, medical imaging, and 2-D and 3-D rendering. Existing approaches for manipulating these datasets are incomplete: The performance of SQL queries for manipulating large numeric datasets is not competitive with specialized tools. Database extensions for processing multidimensional discrete data can only model regular, rectilinear grids. Visualization software libraries are designed to process arbitrary gridded datasets efficiently, but no algebra has been developed to simplify their use and afford optimization. Further, these libraries are data dependent – physical changes to data representation or organization break user programs. In this paper, we present an algebra of gridfields for manipulating arbitrary gridded datasets, algebraic optimization techniques, and an implementation backed by experimental results. We compare our techniques to those of Geographic Information Systems (GIS) and visualization software libraries, using real examples from an Environmental Observation and Forecasting System. We find that our approach can express optimized plans inaccessible to other techniques, resulting in improved performance with reduced programming effort.     

Thermostabile Bindung von Aromastoffen an Stärke Teil 1: Bindung durch Gefriertrocknen

Thermostable Binding of Aroma Compounds to Starch. Part 1: Binding by Freeze-Drying. By freeze-drying of aqueous emulsions or suspensions of menthol, pyrazine, thymol, vanillin or peppermint oil and solutions of native or modified starches, amylose, amylopectin Or β-cyclodextrin sorbates were prepared. After heating to 180°C the aroma compounds were bound thermostable and in most cases also stable during extrusion. In general the adsorbed amounts decreased in the order cyclodextrin, amylose, potato starch, waxy maize starch, maize or tapioca starch, wheat starch, amylopectin. Some modified maize starches adsorbed greater amounts than native maize starch. Menthol and thymol were better bound to high-amylose starches, vanillin and pyrazine better to high-amylopectin starches, but vanillin best to cyclodextrin and pyrazine to maltodextrin (DE 4–5). The desorption of the aroma compounds during chewing in the mouth was limited after formation of channel inclusion compounds with amylose.