1,721,450 research outputs found
Gerhard C. Matzner
No full textBlack and white head shot photograph of Gerhard C. Matzner, education professor 1955-1983.https://thekeep.eiu.edu/archives_faculty_mr/1031/thumbnail.jp
Time-Optimal Transport of a Harmonic Oscillator: Analytic Solution
Full text linkMotivated by the experimental transport of a trap with a quantum mechanical
system modeled as a harmonic oscillator (h.o.) the corresponding classical
problem is investigated. Protocols for the fastest possible transport of a
classical h.o. in a wagon over a distance d are derived where both initially
and finally the wagon is at rest and the h.o. is in its equilibrium position
and also at rest. The acceleration of the wagon is assumed to be bounded. For
fixed oscillator frequency \Omega it is shown that there are in general three
switches in the acceleration and for special values of \Omega only one switch.
In the latter case the optimal transport time is T_abs , that of a wagon
without oscillator. The optimal transport time and the switch times are
determined. It is shown that in some cases it is advantageous to go backwards
for a while. In addition a time-dependent \Omega(t), bounded by \Omega_ and
\Omega+ , is allowed. In this case the behavior depends sensitively on
{\Omega}_+ and is spelled out in detail. In particular, depending on \Omega_+ ,
T_abs may be obtained in continuously many ways.Comment: 10 pages, 11 figure
Gerhard C. Gerhardi : Geld und Gesellschaft im Theater des Ancien Régime, 1983
No full textBaasner Frank. Gerhard C. Gerhardi : Geld und Gesellschaft im Theater des Ancien Régime, 1983. In: Dix-huitième Siècle, n°17, 1985. Le protestantisme français en France. p. 480
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
High-speed driving of a two-level system
No full textA simple result is found for the optimal protocol of drivings for a general two-level Hamiltonian, which transports a given initial state to a given final state in minimal time, under additional conditions on the drivings. If one of the three possible drivings is unconstrained in strength the problem is analytically completely solvable. A surprise arises for a class of states when one driving is bounded by a constant c and the other drivings are constant. Then, for large c, the optimal driving is of type bang-off-bang and for increasing c one recovers the unconstrained result. However, for smaller c the optimal driving can suddenly switch to bang-bang type. It is also shown that for general states one may have a multistep protocol
Driving at the Quantum Speed Limit: Optimal Control of a Two-Level System
No full textA remarkably simple result is derived for the minimal time T-min required to drive a general initial state to a final target state by a Landau-Zener-type Hamiltonian or, equivalently, by time-dependent laser driving. The associated protocol is also derived. A surprise arises for some states when the interaction strength is bounded by a constant c. Then, for large c, the optimal driving is of type bang-off-bang and for increasing c one recovers the unconstrained result. However, for smaller c the optimal driving can suddenly switch to bang-bang type. We discuss the notion of quantum speed limit time
Blinking molecules: Determination of photophysical parameters from the intensity correlation function
No full textAn explicit expression is given for the correlation function of blinking systems, i.e., systems exhibiting light and dark periods in their fluorescence. We show through the example of terrylene in a crystalline host that it is possible to determine by means of this explicit expression photophysical parameters, like Einstein coefficients and the mean light and dark periods. In addition we obtain further parameters like the frequency of the various intensity periods and the probability density of photons scattered off the host crystal. It turns out that this approach is simpler and allows greater accuracy than previous procedures. (C) 2003 American Institute of Physics
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