Mapping the Wigner distribution function of the Morse oscillator into a semi-classical distribution function

The mapping of the Wigner distribution function (WDF) for a given bound-state onto a semiclassical distribution function (SDF) satisfying the Liouville equation introduced previously by us is applied to the ground state of the Morse oscillator. Here we give results showing that the SDF gets closer to the corresponding WDF as the number of levels of the Morse oscillator increases. We find that for a Morse oscillator with one level only, the agreement between the WDF and the mapped SDF is very poor but for a Morse oscillator of ten levels it becomes satisfactory.Comment: Revtex, 27 pages including 13 eps figure

Cómo hombres y mujeres aprenden movimientos de manera autodirigida : diferencias de género en la utilización de las estrategias de aprendizaje

Learning strategies, defined as specific and situational learning activities, have been a topic of psychological research for many years, mostly in academic context. The findings indicate gender differences in the use of learning strategies. This paper presents a study in which male and female subjects (N = 30) autonomously learned how to juggle balls. The learning strategies were measured by a questionnaire. The results reveal numerous gender differences in the use of single learning strategies rather than in the use of types of learning strategie

String Picture of Bose-Einstein Condensation

A nonrelativistic Bose gas is represented as a grand-canonical ensemble of fluctuating closed spacetime strings of arbitrary shape and length. The loops are characterized by their string tension and the number of times they wind around the imaginary time axis. At the temperature where Bose-Einstein condensation sets in, the string tension, being determined by the chemical potential, vanishes, the system becomes critical, and the strings proliferate. A comparison with Feynman's description in terms of rings of cyclicly permuted bosons shows that the winding number of a loop corresponds to the number of particles contained in a ring.Comment: 13 pages, 6 figures; references adde

Hazard-free clock synchronization

The growing complexity of microprocessors makes it infeasible to distribute a single clock source over the whole processor with a small clock skew. Hence, chips are split into multiple clock regions, each covered by a single clock source. This poses a problem for communication between these clock regions. Clock synchronization algorithms promise an advantage over state-of-the-art solutions, such as GALS systems. When clock regions are synchronous the communication latency improves significantly over handshake-based solutions. We focus on the implementation of clock synchronization algorithms. A major obstacle when implementing circuits on clock domain crossings are hazardous signals. We can formally define hazards by extending the Boolean logic by a third value u. In this thesis, we describe a theory for designing and analyzing hazard-free circuits. We develop strategies for hazard-free encoding and construction of hazard-free circuits from finite state machines. Furthermore, we discuss clock synchronization algorithms and a possible combination of them. In the end, we present two implementations of the GCS algorithm by Lenzen, Locher, and Wattenhofer (JACM 2010). We prove by rigorous analysis that the systems implement the algorithm. The theory described above is used to prove that our clock synchronization circuits are hazard-free (in the sense that they compute the most precise output possible). Simulation of our GCS system shows that it achieves a skew between neighboring clock regions that is smaller than a few inverter delays.Aufgrund der zunehmenden Komplexität von Mikroprozessoren ist es unmöglich, mit einer einzigen Taktquelle den gesamten Prozessor ohne großen Versatz zu takten. Daher werden Chips in mehrere Regionen aufgeteilt, die jeweils von einer einzelnen Taktquelle abgedeckt werden. Dies stellt ein Problem für die Kommunikation zwischen diesen Taktregionen dar. Algorithmen zur Taktsynchronisation bieten einen Vorteil gegenüber aktuellen Lösungen, wie z.B. GALS-Systemen. Synchronisiert man die Taktregionen, so verbessert sich die Latenz der Kommunikation erheblich. In Schaltkreisen zwischen zwei Taktregionen können undefinierte Signale, sogenannte Hazards auftreten. Indem wir die boolesche Algebra um einen dritten Wert u erweitern, können wir diese Hazards formal definieren. In dieser Arbeit zeigen wir eine Methode zum Entwurf und zur Analyse von hazard-freien Schaltungen. Wir entwickeln Strategien für Kodierungen die Hazards vermeiden und zur Konstruktion von hazard-freien Schaltungen. Darüber hinaus stellen wir Algorithmen Taktsynchronisation vor und wie diese kombiniert werden können. Zum Schluss stellen wir zwei Implementierungen des GCS-Algorithmus von Lenzen, Locher und Wattenhofer (JACM 2010) vor. Oben genannte Mechanismen werden verwendet, um formal zu beweisen, dass diese Implementierungen korrekt sind. Die Implementierung hat keine Hazards, das heißt sie berechnet die bestmo ̈gliche Ausgabe. Anschließende Simulation der GCS Implementierung erzielt einen Versatz zwischen benachbarten Taktregionen, der kleiner als ein paar Gatter-Laufzeiten ist

Collisional Semiclassical Aproximations in Phase-Space Representation

The Gaussian Wave-Packet phase-space representation is used to show that the expansion in powers of $\hbar$ of the quantum Liouville propagator leads, in the zeroth order term, to results close to those obtained in the statistical quasiclassical method of Lee and Scully in the Weyl-Wigner picture. It is also verified that propagating the Wigner distribution along the classical trajectories the amount of error is less than that coming from propagating the Gaussian distribution along classical trajectories.Comment: 20 pages, REVTEX, no figures, 3 tables include

Investigation of the contact resistance as a function of the temperature for connectors and wire terminals

The hardness of coating materials such as tin or gold is temperature-dependent, so the contact area and thus the contact resistance change depending on the temperature. Contact resistance measurements are carried out on hard gold- and tin-coated connector contacts at elevated temperatures. It is shown that the contact resistance decreases significantly with increasing temperature. Tests are also being carried out with solid and stranded copper wires. In addition to the hardness, foreign layers on the copper conductors have a further influence on the contact resistance

The Role of Institutional and Structural Differences for City-Specific Arrangements of Urban Migration Regimes

In recent years, an increasing influx of migrants to Europe has led to a heated public discourse about integration capacities within receiving countries such as Germany. During this period, German society, with its changeful immigration history, is again challenged to provide policy responses and foster migrant integration, especially in urban areas. The efforts of cities along that path, however, vary greatly. Complementing locality approaches on immigration and integration policies, which are focused on metropolises and the U.S.-American context, this article is an empirical application for understanding institutional and structural conditions for local variations in integration strategies in Germany by presenting a comparative analysis of four mid-sized cities. The particular research interest lies on discourses from interviews with local authorities and civil society actors. Our analysis reveals city-specific streamlines: For instance, discourses at a center of the ‘knowledge society’ focused on a strong municipal power structure that allowed communally-financed, sustainable projects to evolve from a historically-grounded commitment to welcome migrants and from high financial capacities at its disposal. In another case, discourses revolved around a city’s financially constraints, which were equalized by compensatory civil society networks. In other cities, progress was associated with spontaneous local happenings or individual innovative leadership. These street-level patterns create a degree of locality within the global migration discourse, since they emerge from the interplay of financial, economic, and demographic features; historical concepts; or local events. We therefore contend that urban planning initiatives would profit from considering place-specific institutions that influence integration stakeholders, which are regime-makers and foster institutional, migration-led changes

Shifting paradigms in Europe's approach to cyber defence: ambitions to disrupt malicious cyber activity need to protect norms as well as networks

As high-level European Union (EU) policy documents call for investment in active cyber defence capabilities, the legal and political powers for their use remain ill-defined. To demonstrate their commitment to principles of responsible state behaviour and due diligence, the EU and its member states have a duty to establish the normative foun­dations for the use of active cyber defence measures ahead of their deployment, while carefully managing the risk of a gradual militarisation of the cyber and information domain. (author's abstract

Brains behind barbed wire

https://stars.library.ucf.edu/prism/1159/thumbnail.jp