17,883 research outputs found
q-Differential equations for q-classical polynomials and q-Jacobi-Stirling numbers
No full textWe introduce, characterise and provide a combinatorial interpretation for the so-called q-Jacobi–Stirling numbers.
This study is motivated by their key role in the (reciprocal) expansion of any power of a second order
q-differential operator having the q-classical polynomials as eigenfunctions in terms of other even order operators,
which we explicitly construct in this work. The results here obtained can be viewed as the q-version of
those given by Everitt et al. and by the first author, whilst the combinatorics of this new set of numbers is a
q-version of the Jacobi–Stirling numbers given by Gelineau and the second author
Author Q and A with editor Phil Crockett Thomas and contributors on abolition science fiction
No full textIn this author Q&A, Rémy-Paulin Twahirwa speaks to editor Phil Crockett Thomas and contributors about their recent collection, Abolition Science Fiction, a collection of short science fiction stories written by activists and scholars involved in prison abolition and transformative justice in the UK
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Network Q
No full textA press release from Network Q announcing that they will begin featuring Brian McNaught, a gay columnist and author, for a monthly segment
Network Q
No full textA press release from Network Q announcing that they will begin featuring Brian McNaught, a gay columnist and author, for a monthly segment
Tobin's Q and Financial Policy
No full textRecent research in macroeconomics has emphasized the importance of linking the financial and real sectors and the need for working with optimizing models. Tobin’s Q model of investment would appear to provide a framework that can satisfy these two criteria. In contrast to the original presentation of the Q model, the formal development has not recognized that the firm actively participates in a number of financial markets; in this broader context, we show that Q is likely to be an uninformative and possibly misleading signal for investment expenditures . We then endeavor to turn this negative theoretical result to positive advantage in resolving a number of empirical problems with Q models, but the modifications dictated by the theory receive little support from the data.
Der Q Q Q Q -Übergang im bakteriellen photosynthetischen Reaktionszentrum von
No full textDas bakterielle Reaktionszentrum von R. sphaeroides stellt ein Modellsystem zum Studium der Photosynthese dar und führt bei Lichtanregung eine Ladungstrennung durch, die von einem Bakteriochlorophyll-Dimer zu zwei Ubichinon-Molekülen, Q A und Q B, reicht. Der zentrale finale Elektronentransferschritt Q A - - Q B Q A Q B - wurde mit zeitauflösender Stepscan-FTIR-Differenzspektroskopie und ortsspezifischer Mutagenese untersucht. Der Q A - - Q B Q A Q B - -Übergang verläuft als Drei-Schritt-Prozess mit 1 = 12 s, 2 = 150 s und 3 = 1,1 ms. "Conformational gating" bestimmt die ersten beiden Schritte, in denen unterschiedliche Populationen von Q B von einem intermediären Elektronendonor X reduziert werden. Die Oxidation von Q A - - ist davon entkoppelt und läuft mit einer langsameren dritten Rate ab. Mit allen Raten finden Protonentransferreaktionen statt. Das Ergebnis, dass die Reduktion von Q B der Oxidation von Q A - - vorausgeht, führt zu einem völlig neuen Mechanismusvorschlag für den Q A - - Q B Q A Q B - -Übergang.The bacterial reaction centre of R. sphaeroides, a model system for studying photosynthesis, performs charge separation across the membrane from a bacteriochlorophyll dimer to two ubiquinone-10 molecules, Q A and Q B. The final electron transfer step Q A - - Q B Q A Q B - is investigated applying time-resolved stepscan-FTIR difference spectroscopy and site-directed mutagenesis. The Q A - - Q B Q A Q B - transition can be described as a three-step process with 1 = 12 s, 2 = 150 s and 3 = 1,1 ms. Conformational gating controls the first two steps in which different populations of Q B are reduced by an intermediary donor X. The oxidation of Q A - - is kinetically discoupled and takes place on a slower time scale. All the steps are complexly coupled to proton transfer reactions. Especially the finding that Q B reduction proceeds Q A - - oxidation leads to a completely new mechanism
A Q-learning based multi-strategy integrated artificial bee colony algorithm with application in unmanned vehicle path planning
No full textArtificial bee colony (ABC) is a prominent algorithm that offers great exploration capabilities among various meta-heuristic algorithms. However, its monotonous and one-dimensional search strategy limits its searching performance in the solving process. Thus, to address this issue, a Q-learning based multi-strategy integrated ABC algorithm (QMABC) is proposed. In the QMABC, multiple search strategies are proposed to utilize different individual experiences and search approaches for solution updates. Then, Q-learning is employed for strategy selection. In comparison to previous studies, this paper introduces more effective state and action configurations within the framework of Q-learning. To evaluate the performance of the QMABC, CEC 2017 benchmark functions are adopted to compare it to different meta-heuristic algorithms including ABC based and non-ABC based algorithms. Moreover, applications in path planning are implemented to further verify the effectiveness of the QMABC. Overall, it should be highlighted that the proposed QMABC demonstrates superiority in both numerical and practical experiments.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Discrete Mathematics and Optimizatio
Meromorphic solutions of linear q-difference equations
No full textInternational audienceIn this article, we construct explicit meromorphic solutions of first order linear q-difference equations in the complex domain and we describe the location of all their zeros and poles. The homogeneous case leans on the study of four fundamental equations, providing the previous informations in the framework of entire or meromorphic coefficients. The inhomogeneous situation, which stems from the homogeneous one and two fundamental equations, is also described in detail. We also address the case of higher-order linear q-difference equations, using a classical factorization argument. All these results are illustrated by several examples
Event-Based Communication in Distributed Q-Learning
No full textWe present an approach to reduce the communication of information needed on a Distributed Q-Learning system inspired by Event Triggered Control (ETC) techniques. We consider a baseline scenario of a Distributed Q-Learning problem on a Markov Decision Process (MDP). Following an event-based approach, N agents sharing a value function explore the MDP and compute a trajectory-dependent triggering signal which they use distributedly to decide when to communicate information to a central learner in charge of computing updates on the action-value function. These decision functions form an Event Based distributed Q learning system (EBd-Q), and we derive convergence guarantees resulting from the reduction of communication. We then apply the proposed algorithm to a cooperative path planning problem, and show how the agents are able to learn optimal trajectories communicating a fraction of the information. Additionally, we discuss what effects (desired and undesired) these event-based approaches have on the learning processes studied, and how they can be applied to more complex multi-agent systems.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Manuel Mazo J
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