Thermobaric Effect on Melt-Textured MBa2_2Cu3_3O7−δ_{7-\delta} (M = Y, Nd)

The effect of a short (10-30 min) thermobaric action (in the 1-5 GPa pressure and 700-1300$^\circ$C temperature range) on the structure, superconductive and mechanical properties of melt-textured-MBa$_2$Cu$_3$O$_{7-\delta}$ (M=Y, Nd) or MT-MBCO have been studied. The existence has been established of pressure-temperature--time conditions (2 GPa, 800$^\circ$C for 30 min and 900-950$^\circ$C for 15 min for MT-YBCO; 5 GPa, 850-900$^\circ$C for 15 min for MT-NdBCO) the treatment under which allows superconductive properties of the materials (because of the contact with zirconia and high pressure) to be preserved or improved, mechanical characteristics increased and the materials condensed.Comment: 2 pages (tex), 2 figures (eps), to be presented at LT2

A Novel System of Cytoskeletal Elements in the Human Pathogen Helicobacter pylori

Pathogenicity of the human pathogen Helicobacter pylori relies upon its capacity to adapt to a hostile environment and to escape from the host response. Therefore, cell shape, motility, and pH homeostasis of these bacteria are specifically adapted to the gastric mucus. We have found that the helical shape of H. pylori depends on coiled coil rich proteins (Ccrp), which form extended filamentous structures in vitro and in vivo, and are differentially required for the maintenance of cell morphology. We have developed an in vivo localization system for this pathogen. Consistent with a cytoskeleton-like structure, Ccrp proteins localized in a regular punctuate and static pattern within H. pylori cells. Ccrp genes show a high degree of sequence variation, which could be the reason for the morphological diversity between H. pylori strains. In contrast to other bacteria, the actin-like MreB protein is dispensable for viability in H. pylori, and does not affect cell shape, but cell length and chromosome segregation. In addition, mreB mutant cells displayed significantly reduced urease activity, and thus compromise a major pathogenicity factor of H. pylori. Our findings reveal that Ccrp proteins, but not MreB, affect cell morphology, while both cytoskeletal components affect the development of pathogenicity factors and/or cell cycle progression

Interface estimates for the fully anisotropic Allen-Cahn equation and anisotropic mean curvature flow

In this paper, we prove that solutions of the anisotropic Allen-Cahn equation in double-obstacle form with kinetic term \begin{displaymath} \varepsilon \beta(\nabla \varphi) \partial_t \varphi - \varepsilon \nabla A'(\nabla \varphi) - \frac{1}{\varepsilon} \varphi = \frac{\pi}{4} u \quad \mbox{ in } [|\varphi| < 1], \end{displaymath} where $\ A\$ is a convex function, homogeneous of degree two, and $\ \beta\$ depends only on the direction of $\ \nabla \varphi\$, converge to an anisotropic mean-curvature flow \begin{displaymath} \beta(N) V_N = - \mbox{tr}(B(N) D^2 B(N) R) - B(N) u. \end{displaymath} Here \ V_N \mbox{ and } R\ respectively denote the normal velocity and the second fundamental form of the interface, and $\ B := \sqrt{2A}\$. We prove this in the case when the above flow admits a smooth solution, and we establish that the Hausdorff-distance between the zero-level set of $\ \varphi\$ and the interface of the flow is of order $\ O(\varepsilon^2)\$

An approximation of the Stefan problem with Gibbs-Thomson law by using functionals of the Landau-Ginzburg theory as free energy

We prove that the quasistationary phase field equations #theta#_t(u+#phi#)-#DELTA# = f, -2#epsilon##DELTA##phi#+1/#epsilon#g'(#phi#) u, where g(t) = (t&quot;2 - 1)&quot;2 is a double-well potential, admit a solution and that the solutions converge for #epsilon##-&gt;#0 to solutions of the Stefan problem with Gibbs-Thomson law. (orig.)Available from TIB Hannover: RO 5389(339) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Untersuchung der elektromagnetischen Eigenschaften des Solargenerators in netzgekoppelten photovoltaischen Stromversorgungsanlagen Abschlussbericht

This BMBF-sponsored project, which was carried out from August 1994 to April 1997, has achieved its goal of characterizing the electromagnetic properties of solar generators of grid-coupled photovoltaic power systems. The focus of the study was on systems and components that are typically used in the household sector (range of power output 1-10 kW_p), and which have become widely distributed, especially also among private house-owners and builders, not lastly by the 1000-roofs photovoltaics programme. As far as time permitted within the framework of this project, current trends in inverter technology (string-type inverters and modular inverters) were also taken into account.- The main conclusion from the project is as follows: Photovoltaic plants are principally capable of generating higher-frequency electromagnetic disturbances (both in line-transmitted and radiated form). Moreover, given certain boundary conditions, these disturbances may be emitted to the environment both via the AC side and via the DC side/solar generator. (orig./AKF)In dem seit August 1994 bis April 1997 laufenden BMBF-Projekt wurde das Ziel einer Charakterisierung der elektromagnetischen Eigenschaften des Solargenerators netzgekoppelter photovoltaischer Stromversorgungsanlagen erreicht. Schwerpunkt der Untersuchungen waren dabei Anlagen und Komponenten, die typischerweise im Hausbereich eingesetzt werden (Leistungsbereich 1-10 kW_p) und die nicht zuletzt durch das 1000 Daecher-Photovoltaikprogramm weite Verbreitung gerade auch bei privaten Hauseigentuemern und Bauherren gefunden haben. Soweit im Rahmen der Projektlaufzeit noch moeglich, wurden auch aktuelle Tendenzen der Wechselrichtertechnik (String- und Modulwechselrichter) beruecksichtigt. Wesentlichstes Ergebnis der Projektarbeiten ist die Aussage, dass photovoltaische Anlagen grundsaetzlich in der Lage sind, hoeherfrequente elektromagnetische Stoerungen (sowohl leitungsgebunden als auch gestrahlt) zu erzeugen, und sowohl ueber die Wechselstromseite als auch ueber die Gleichstromseite/Solargenerator unter gewissen Randbedingungen diese Stoerungen nach aussen emittiert werden koennen. (orig.)Available from TIB Hannover: F98B313+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Photovoltaische Energieversorgung von Inselsystemen Abschlussbericht

In this research report the following programme is explained: 1. Energy analysis and measures for energy conservation; 2. Plant lay-out; 3. Energy management; 4. Inverted rectifiers; 5. Integration into roofs; 6. Use of wind energy; 7. Electric safety in photovoltaic power plants; 8. Data acquisition; 9. Serial effects; 10. Know-how transfer (HW)Im vorliegenden Forschungsbericht wird folgendes Programm erlaeutert: 1. Energieanalyse + Energiesparmassnahmen; 2. Anlagenauslegung; 3. Energiemanagement; 4. Wechselrichter; 5. Dachintegration; 6. Windenergienutzung; 7. Elektrische Sicherheit in Photovoltaic-Anlagen; 8. Messwerterfassung; 9. Soziale Effekte; 10. Know-How-Transfer. (HW)Available from TIB Hannover: F95B1017+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Removability of point singularities of Willmore surfaces

SIGLEAvailable from TIB Hannover: RS 2745(47) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDeutsche Forschungsgemeinschaft (DFG), Bonn (Germany)DEGerman