Application of Finite Strain Landau Theory To High Pressure Phase Transitions

In this paper we explain how to set up what is in fact the only possible consistent construction scheme for a Landau theory of high pressure phase transitions that systematically allows to take into account elastic nonlinearities. We also show how to incorporate available information on the pressure dependence of elastic constants taken from experiment or simulation. We apply our new theory to the example of the high pressure cubic-tetragonal phase transition in Strontium Titanate, a model perovskite that has played a central role in the development of the theory of structural phase transitions. Armed with pressure dependent elastic constants calculated by density functional theory, we give a both qualitatively as well as quantitatively satisfying description of recent high precision experimental data. Our nonlinear theory also allows to predict a number of additional elastic transition anomalies that are accessible to experiment.Comment: submitted to Phys. Rev. Let

Achilles\u27 heel of Grapevine Downy Mildew - The Contractile Vacuole as Target for Potential Control Strategies in Viticulture

Downy Mildew (DM) is a major disease in viticulture since the 19th century, caused by the plant parasitic oomycete Plasmopara viticola, which has algal ancestors. Different microscopy techniques in this study illustrate the importance and fragility of the contractile vacuole in zoospores. Ecologically friendly DM control can be achieved with glycyrrhizin or the root extract of G. glabra, both inhibiting the contractile vacuole resulting in burst or premature encystment

Von der Praxis für die Praxis:Kursleiter/innen-Berichte über Erfahrungen mit Lernsoftware in Grundbildung und Alphabetisierung

Kann der Einsatz von Neuen Medien das Lernen Erwachsener in Grundbildung und Alphabetisierung positiv beeinflussen? Acht Erfahrungsberichte aus der Praxis geben wichtige Hinweise wie Einsatzmöglichkeiten ausgelotet, Schwierigkeiten überwunden und Chancen eines computergestützten Lernprozesses genutzt werden können. Die Rolle des Lehrenden verändert sich ebenso wie sich das Lernen der Teilnehmenden durch mehr Selbstständigkeit verändert. Auch an die Lernsoftware sind besondere Anforderungen zu stellen

¿Una especie de hagiografía? Plutarco y la tradición histórica en la Vida de Emilio Paulo

La Vida de Emilio Paulo destaca como uno de los tratamientos más favorables de un héroe plutarqueo. No es sólo que el proemio afirme enfáticamente el enlace personal entre el biógrafo y sus personajes ejemplares, sino que toda la narración presenta a Emilio como líder virtuoso y educador sabio, que encarna la tradición del mos maiorum y que actúa conforme al modelo del estadista-filósofo. En consecuencia, la Vida ha sido descrita como una obra de ‘hagiografía pagana’ (Barzanò 1994/96), o sea, como una tentativa deliberada de Plutarco de minimizar los aspectos menos brillantes de la carrera de su héroe y de absolver a Emilio de cualquier fechoría. Sin embargo, es bastante dudoso que las fuentes del biógrafo hayan proporcionado un cuadro mucho más equilibrado, considerando el hecho de que Polibio y Livio no son menos generosos en sus elogios de las virtudes tradicionales y de los destacados logros de Emilio en Roma y ultramar, y teniendo en cuenta que ya a mediados del siglo II a.C. el vencedor de Pidna fue usado, según atestigua Plutarco, como modelo de excelencia aristocrática. Por supuesto, el queronense escoge reelaborar esta imagen, centrándose en temas relevantes para sus propios intereses y experiencias, pero en vez de distorsionar gravemente los datos disponibles con el fin de construir a un estadista impecable, su relato se basa en la tradición histórica y la desarrolla a su manera.The Life of Aemilius Paullus stands out as one of the most favourable treatments of a Plutarchan hero. Not only does the proem emphatically assert the biographer’s personal association with his exemplary subjects, but throughout the narrative Aemilius emerges as a virtuous leader and wise educator, embodying the tradition of mos maiorum and conforming to the model of the philosopher statesman. Consequently, the Life has been described as a piece of ‘pagan hagiography’ (Barzanò 1994/96), a deliberate attempt by Plutarch to suppress the less brilliant side of his hero’s career and to clear Aemilius of any wrongdoing. However, it is rather doubtful that the biographer’s sources provided a much more balanced picture. In fact, Polybius and Livy are no less generous in their praise for Aemilius’ traditional virtues and outstanding achievements at home and abroad. What is more, the victor of Pydna is attested to have been used as an exemplar of aristocratic excellence as early as the mid-second century BC. Of course, Plutarch chooses to re-elaborate this image, focusing on themes relevant to his own interests and experience. Nevertheless, he does not seek to construct a stainless statesman by grossly distorting the information at his disposal; rather he builds on the historical tradition and develops it in his own way

Tandem: A Context-Aware Method for Spontaneous Clustering of Dynamic Wireless Sensor Nodes

Wireless sensor nodes attached to everyday objects and worn by people are able to collaborate and actively assist users in their activities. We propose a method through which wireless sensor nodes organize spontaneously into clusters based on a common context. Provided that the confidence of sharing a common context varies in time, the algorithm takes into account a window-based history of believes. We approximate the behaviour of the algorithm using a Markov chain model and we analyse theoretically the cluster stability. We compare the theoretical approximation with simulations, by making use of experimental results reported from field tests. We show the tradeoff between the time history necessary to achieve a certain stability and the responsiveness of the clustering algorithm