Determination of the transition point in a boundary layer by the measurement of pressure fluctuation

A method is developed for determining the laminar-to-turbulent transition point in a boundary layer. The method involves the measurement of pressure on the surface of the body and the computation of pressure fluctuations. This method of determining the transition point is suitable when visualization methods cannot be used

Prevention of cyber crime in the primary and secondary school

The article discusses the current state of knowledge of pupils in primary and secondary schools on cyber crime and their attitudes towards it. Based on the survey was obtained data on the attitudes of students to various illegal activities when using computers. The results of the evaluation data were then proposed recommendations for the preparation of teaching materials that teachers use in every teaching through computers and in computer science.Článek pojednává o současném stavu vědomostí žáků základních a středních škol o počítačové kriminalitě a o jejich postojích k ní. Na základě dotazníkového šetření byla získána data o postojích žáků k různým nelegálním činnostem při použití počítačů. Z výsledků vyhodnocení dat pak byly navrženy doporučení pro přípravu výukových materiálů které by učitelé využívali při každé výuce pomocí počítačů zejména při výuce informatiky.The article discusses the current state of knowledge of pupils in primary and secondary schools on cyber crime and their attitudes towards it. Based on the survey was obtained data on the attitudes of students to various illegal activities when using computers. The results of the evaluation data were then proposed recommendations for the preparation of teaching materials that teachers use in every teaching through computers and in computer science

Constance Phaulkon: Myth or reality?

This journal has been published at different time periods under the following titles: Explorations: A Graduate Student Journal of Southeast Asian Studies, Explorations in Southeast Asian Studies, and The Journal of the Southeast Asian Studies Association.The Student Activities Program Fee Boar

Investigation of A1g phonons in YBa2Cu3O7 by means of LAPW atomic-force calculations

We report first-principles frozen-phonon calculations for the determination of the force-free geometry and the dynamical matrix of the five Raman-active A1g modes in YBa2Cu3O7. To establish the shape of the phonon potentials atomic forces are calculated within the LAPW method. Two different schemes - the local density approximation (LDA) and a generalized gradient approximation (GGA) - are employed for the treatment of electronic exchange and correlation effects. We find that in the case of LDA the resulting phonon frequencies show a deviation from experimental values of approximately -10%. Invoking GGA the frequency values are significantly improved and also the eigenvectors are in very good agreement with experimental findings.Comment: 15 page

Secretion processes as a limiting factor of protein production in Bacillus

Summary Protein secretion involves several important sequential steps. First, proteins to be secreted must be recognized and their translocation-competent conformation must be ensured. This is followed by the overcoming of two barriers, the cell membrane and the cell wall. The active transport across the membrane can occur by several well-studied mechanisms, the most notably of them are known as "general secretory" (Sec) and "twin-arginine translocation" (Tat). For the passage through the cell wall, on the other hand, understanding is still almost completely lacking. In this work, I investigated this process, using super-resolution fluorescence microscopy to visualize AmyE-mCherry during secretion in Bacillus subtilis and Bacillus licheniformis. The overexpressed fusion protein localized as distinct foci in the cell envelope, which were mostly lost upon degradation of the bacterial cell wall through treatment with lysozyme. I could also show that AmyE is released from the cells at discrete zones, similar to the localization of fluorescently labeled AmyE as foci inside the envelope. High-level protein secretion peaked at the transition from exponential growth to the stationary phase and appears to be restricted to a subpopulation of cells, which presumably is also the case for general protein secretion. Time lapse experiments revealed the AmyE-mCherry foci to be statically positioned throughout several minutes, in contrast to the lateral mobility of Secmachinery associated membrane proteins SecA and SecDF, labeled with mNeonGreen. Interestingly, the AmyE-mCherry foci displayed considerable fluctuations of fluorescence intensities within a minutes-time-scale, suggesting visualized diffusion of proteins along the passage through the cell walls meshwork. This idea of diffusion is supported by recent AFM Imaging results of B. subtilis, revealing a heterologous cell wall structure with deep pores its peptidoglycan surface. For large parts of industrial biotechnology, the secretion of microbially produced enzymes and proteins into the culture supernatant is of enormous relevance, due to the lower costs for subsequent processing associated with this method as compared to the disruption of the producing cells. Studies investigating secretion efficiency in Bacillus species, have revealed numerous influencing factors. Since the bacterial cell wall is often overlooked in the search for secretion bottlenecks, I targeted autolysins that can affect cell wall thickness and the density of the meshwork. While absence of LytD had little effect on secretion, deletion of lytC and lytF significantly impaired AmyE transport to the outside of the cell. By introducing additional genes encoding the autolysins LytC and LytF or the cell wall hydrolase PBP5 (dacA), I was able to improve secretion by up to 200%. These findings suggest that cell wall permeability for secreted proteins is modulated by autolysin activity. Flotillins, which are thought to form functional membrane microdomains (FMM) in B. subtilis, are often linked with secretion, although the nature of this connection is not exactly clear. To approach this subject, I used a ΔyuaG (FloT) deletion strain with reduced AmyE secretion and showed that the addition of the membrane fluidizer benzyl alcohol could recover the AmyE secretion level of the wild type. This result indicates, that flotillins affect protein secretion in B. subtilis through the ability to improve membrane fluidity. Furthermore, I was able to double the efficiency of AmyE secretion of B. subtilis by introducing an additional gene encoding FloT

Engagement 2.0. Vom passiven Wahrnehmen zum aktiven Nutzen neuer Kommunikationstechnologien

Im vorliegenden Beitrag beschreiben die Autoren einen seit zwei Jahren am Bundesinstitut für Erwachsenenbildung situierten Kurs, der engagierte Menschen in die Kommunikationstechniken und -werkzeuge im sogenannten Web 2.0 einführt. Als "politische Kommunikation" betrachten sie alle öffentlichkeitswirksamen bzw. zielgruppenbezogenen Aktivitäten für Anliegen, die im Selbstbewusstsein der AkteurInnen als öffentlich, als Interessen der Allgemeinheit oder aber auch als moralische Ansprüche an die Gesellschaft verstanden werden. Den Abschluss des Beitrages bildet der Ausblick auf eine im Entstehen befindliche Webcommunity der AbsolventInnen des Kurses. (DIPF/Orig.)The authors of the present article describe a course at the Austrian Federal Institute of Adult Education (bifeb) that has introduced dedicated people to Web 2.0 communication technologies and tools for the last two years. For the authors, “political communication” represents all public-oriented and target group related activities surrounding matters that are considered to be public in the self-awareness of those involved, interests of the general public or also moral demands on society. The end of the article provides a panorama of the web community that is being created by the course graduates. (DIPF/Orig.

Infrared optical properties of Pr2CuO4

The ab-plane reflectance of a Pr2CuO4 single crystal has been measured over a wide frequency range at a variety of temperatures, and the optical properties determined from a Kramers-Kronig analysis. Above ~ 250 K, the low frequency conductivity increases quickly with temperature; the resistivity follows the form e^(E_a/k_BT), where E_a ~ 0.17 eV is much less than the inferred optical gap of ~ 1.2 eV. Transport measurements show that at low temperature the resistivity deviates from activated behavior and follows the form e^[(T_0/T)^1/4], indicating that the dc transport in this material is due to variable-range hopping between localized states in the gap. The four infrared-active Eu modes dominate the infrared optical properties. Below ~ 200 K, a striking new feature appears near the low-frequency Eu mode, and there is additional new fine structure at high frequency. A normal coordinate analysis has been performed and the detailed nature of the zone-center vibrations determined. Only the low-frequency Eu mode has a significant Pr-Cu interaction. Several possible mechanisms related to the antiferromagnetism in this material are proposed to explain the sudden appearance of this and other new spectral features at low temperature.Comment: 11 pages, 7 embedded EPS figures, REVTeX