Time-dependent fluctuation theorem

The fluctuation theorem (FT) is a generalization of the second law of thermodynamics that applies to small systems observed for short times. For thermostated systems it gives the probability ratio that entropy will be consumed rather than produced. In the present paper, we propose a version of the FT that applies to thermostated dissipative systems which respond to time-dependent dissipative fields. In testing the time-dependent fluctuation theorem we provide convincing evidence that sets of trajectories with conjugate values for the time-integrated entropy production, (±A±δA), are indeed (for time-reversible dynamical systems such as those studied here), time-reversal images of one another. This observation verifies the deep connection between time-reversal symmetry, the fluctuation theorem, and the second law of thermodynamics

Verification of time-reversibility requirementfor systems satisfying the Evans-Searles fluctuation theorem

The Evans-Searles fluctuation theorem (ESFT) has been shown to be applicable in the near- and far-from-equilibrium regimes for systems with both constant and time-dependent external fields. The derivations of the ESFT have assumed that the external field has a definite parity under a time-reversal mapping. In the present paper, we confirm that the time-reversibility of the system dynamics is a necessary condition for the ESFT to hold. The manner in which the ESFT fails for systems that are not time-reversible is presented, and results are shown which demonstrate that systems which fail to satisfy the ESFT may still satisfy the Crooks relation (CR)

Revisiting the connection between magnetic activity, rotation period, and convective turnover time for main-sequence stars

The connection between stellar rotation, stellar activity, and convective turnover time is revisited with a focus on the sole contribution of magnetic activity to the Ca II H&K emission, the so-called excess flux, and its dimensionless indicator R$^{+}_{\rm{HK}}$ in relation to other stellar parameters and activity indicators. Our study is based on a sample of 169 main-sequence stars with directly measured Mount Wilson S-indices and rotation periods. The R$^{+}_{\rm{HK}}$ values are derived from the respective S-indices and related to the rotation periods in various $B-V$-colour intervals. First, we show that stars with vanishing magnetic activity, i.e. stars whose excess flux index R$^{+}_{\rm{HK}}$ approaches zero, have a well-defined, colour-dependent rotation period distribution; we also show that this rotation period distribution applies to large samples of cool stars for which rotation periods have recently become available. Second, we use empirical arguments to equate this rotation period distribution with the global convective turnover time, which is an approach that allows us to obtain clear relations between the magnetic activity related excess flux index R$^{+}_{\rm{HK}}$, rotation periods, and Rossby numbers. Third, we show that the activity versus Rossby number relations are very similar in the different activity indicators. As a consequence of our study, we emphasize that our Rossby number based on the global convective turnover time approaches but does not exceed unity even for entirely inactive stars. Furthermore, the rotation-activity relations might be universal for different activity indicators once the proper scalings are used.Comment: 13 pages, 7 figures, accepted for publication in A&

Characterization, Avoidance and Repair of Packet Collisions in Inter-Vehicle Communication Networks

This work proposes a combined and accurate simulation of wireless channel, physical layer and networking aspects in order to bridge the gaps between the corresponding research communities. The resulting high fidelity simulations enable performance optimizations across multiple layers, and are used in the second part of this thesis to evaluate the impact of fast-fading channel characteristics on Carrier-Sense Multiple Access, and to quantify the benefit of successive interference cancellation

The Social Democratic Party of Württemberg during the Republic of Weimar: an analysis of the members of parliament

Die Mitglieder der Landtagsfraktion der SPD im Zeitraum 1919-1932 in Württemberg werden im Hinblick auf ihre sozio-ökonomische und religiöse Biographie analysiert und bezüglich ihrer Parlamentsaktivitäten (Redehäufigkeit, Funktion, Sitzordnung usw.) untersucht. Es wird festgestellt, daß gegen Ende der Weimarer Republik auch die SPD zu organisatorischem Konservatismus neigte, was einen negativen Effekt auf das Image der Fraktion und Partei hatte. Die relativ schlechten Wahlresultate der SPD in Württemberg werden u.a. damit erklärt, daß die Personalstruktur der Partei und Fraktion weder attraktiv war für die Mittelklasse noch für die Radikalen. (pra)"The historical evolution of a party, even of a regional section, is hard to understand without its political-parliamentary leadership elite. Consequently, the biographical background of the Social Democratic politicians in the Landtag of Württemberg during the Republic of Weimar and the resulting parliamentary functions are of central significance to the Social Democracy in Württemberg and its position within the party system." (author's abstract

Characterization, Avoidance and Repair of Packet Collisions in Inter-Vehicle Communication Networks

This work proposes a combined and accurate simulation of wireless channel, physical layer and networking aspects in order to bridge the gaps between the corresponding research communities. The resulting high fidelity simulations enable performance optimizations across multiple layers, and are used in the second part of this thesis to evaluate the impact of fast-fading channel characteristics on Carrier-Sense Multiple Access, and to quantify the benefit of successive interference cancellation

Untersuchungen zum toxischen Potenzial von Zinkoxid-Nanopartikeln an intestinalen Zellmodellen

Zinkoxid-Nanopartikel (ZnO-NP) werden aufgrund ihrer speziellen Eigenschaften in vielen verschiedenen Industriezweigen, aber vor allem auch in verbrauchernahen Bereichen wie der Kosmetikindustrie und Ernährungswirtschaft verwendet, wodurch es zu einer nahezu unvermeidlichen Exposition des Menschen kommt. Die Ergebnisse bisheriger Untersuchungen zu möglichen potenziellen Risiken oral aufgenommener ZnO-NP sind heterogen und lassen keine abschließenden Schlüsse über die Sicherheit dieser zu. Daher wurden in dieser Arbeit mögliche toxische Effekte oral aufgenommener ZnO-NP untersucht. Dafür wurden ZnO-NP (Primärpartikelgröße <50 nm und <100 nm; 12–1229 µM) sowohl in nativer Form als auch nach einem simulierten Verdau zur Annäherung an die in vivo-Gegebenheiten des Gastrointestinaltrakts eingesetzt. Verschiedene Toxizitätstests und die Verwendung intestinaler Modellzelllinien (einfache Zellkulturmodelle: undifferenzierte Caco-2- und LT97-Zellen; komplexere Zellkulturmodelle: differenzierte Caco-2-Zellen in Monokultur und in Cokultur mit HT29-MTX-Zellen) dienten der Untersuchung potenzieller toxischer Effekte von unverdauten und verdauten ZnO-NP. Die Ergebnisse dieser Untersuchungen zeigen, dass sich native und verdaute ZnO-NP in ihrer Löslichkeit und Morphologie unterscheiden. Die Eigenschaften des Dispersionsmittels entscheiden somit über die Partikelcharakteristika von ZnO-NP. Die Behandlung mit unverdauten und verdauten ZnO-NP führte in allen verwendeten Zellmodellen zu einer Erhöhung des zellulären Zinkgehalts. Die unverdauten ZnO-NP wirkten gegenüber den einfachen Zellmodellen toxischer als gegenüber den komplexeren. Die Inkubation von differenzierten Caco-2-Zellen in Monokultur und differenzierten Caco-2/HT29-MTX-Zellen in Cokultur mit unverdauten und verdauten ZnO-NP hatte keine negativen Konsequenzen. Eine simulierte intakte Darmbarriere scheint demnach unempfindlich gegenüber ZnO-NP in physiologisch relevanten Konzentrationen von 123–614 µM zu sein