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See detailStochastic Thermodynamics for Underdamped Brownian Particles: Equivalent Measures, Reversed Stochastic Processes and Feynman-Kac Techniques
Shayanfard, Kamran UL

Doctoral thesis (2017)

Underdamped stochastic thermodynamics provides a handy tool to study a large class of stochastic processes operating out of equilibrium. Colloidal particles in a laser trap, molecular motors and feedback ... [more ▼]

Underdamped stochastic thermodynamics provides a handy tool to study a large class of stochastic processes operating out of equilibrium. Colloidal particles in a laser trap, molecular motors and feedback processes are some of the prominent examples. In the present work we give a mathematical framework for the study of the thermodynamic properties of these phenomena. We focus on Markovian stochastic processes in continuous time and space, and show how the techniques of equivalent measures combined with stochastic solutions of partial differential equations, obtained through Feynman-Kac formula, can be used to derive exact relations between forward and backward diffusion processes. We prove a theorem which allows us to derive the time evolution of an arbitrary path quantity in a simple and systematic way. We further consider a fairly general underdamped stochastic model, and study its nonequilibrium thermodynamic properties at both single trajectory and average levels. For this model, we establish several integral and detailed fluctuation theorems for thermodynamic quantities such as work and entropy production, amongst others. Some of these theorems directly parallel those already obtained in the context of overdamped and master equations, while others are novel. We also discuss some special cases of our model which are directly related to physical systems such as active Brownian particles, feedback processes and isoenergetic stochastic processes. The formalism we develop, and the general model considered here constitute a unified and extended framework for the study of the thermodynamics of underdamped processes, encompassing several physical systems and applications. [less ▲]

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See detailStochastic thermodynamics for “Maxwell demon” feedbacks
Esposito, Massimiliano UL; Schaller, Gernot

in Europhysics Letters [=EPL] (2012), 99(30003),

We propose a way to incorporate the effect of a specific class of feedback processes into stochastic thermodynamics. These “Maxwell demon” feedbacks do not affect the system energetics but only the energy ... [more ▼]

We propose a way to incorporate the effect of a specific class of feedback processes into stochastic thermodynamics. These “Maxwell demon” feedbacks do not affect the system energetics but only the energy barriers between the system states (in a way which depends on the system states). They are thus of a purely informational nature. We show that the resulting formalism can be applied to study the thermodynamic effect of a feedback process acting on electron transfers through a junction. [less ▲]

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See detailStochastic thermodynamics in the strong coupling regime: An unambiguous approach based on coarse graining
Strasberg, Philipp UL; Esposito, Massimiliano UL

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2017)

We consider a classical and possibly driven composite system X ⊗ Y weakly coupled to a Markovian thermal reservoir R so that an unambiguous stochastic thermodynamics ensues for X ⊗ Y . This setup can be ... [more ▼]

We consider a classical and possibly driven composite system X ⊗ Y weakly coupled to a Markovian thermal reservoir R so that an unambiguous stochastic thermodynamics ensues for X ⊗ Y . This setup can be equivalently seen as a system X strongly coupled to a non-Markovian reservoir Y ⊗ R. We demonstrate that only in the limit where the dynamics of Y is much faster than X, our unambiguous expressions for thermodynamic quantities, such as heat, entropy, or internal energy, are equivalent to the strong coupling expressions recently obtained in the literature using the Hamiltonian of mean force. By doing so, we also significantly extend these results by formulating them at the level of instantaneous rates and by allowing for time-dependent couplings between X and its environment. Away from the limit where Y evolves much faster than X, previous approaches fail to reproduce the correct results from the original unambiguous formulation, as we illustrate numerically for an underdamped Brownian particle coupled strongly to a non-Markovian reservoir. [less ▲]

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See detailStochastic thermodynamics of hidden pumps
Esposito, Massimiliano UL; Parrondo, J. M. R.

in Physical Review E - Statistical, Nonlinear, and Soft Matter Physics (2015), 91(5),

We show that a reversible pumping mechanism operating between two states of a kinetic network can give rise to Poisson transitions between these two states. An external observer, for whom the pumping ... [more ▼]

We show that a reversible pumping mechanism operating between two states of a kinetic network can give rise to Poisson transitions between these two states. An external observer, for whom the pumping mechanism is not accessible, will observe a Markov chain satisfying local detailed balance with an emerging effective force induced by the hidden pump. Due to the reversibility of the pump, the actual entropy production turns out to be lower than the coarse-grained entropy production estimated from the flows and affinities of the resulting Markov chain. Moreover, in presence of a large time scale separation between the fast-pumping dynamics and the slow-network dynamics, a finite current with zero dissipation may be produced. We make use of these general results to build a synthetase-like kinetic scheme able to reversibly produce high free-energy molecules at a finite rate and a rotatory motor achieving 100% efficiency at finite speed. © 2015 American Physical Society. [less ▲]

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See detailStochastic thermodynamics of rapidly driven quantum systems,
Bulnes Cuetara, Gregory UL; Engels, Andreas; Esposito, Massimiliano UL

in New Journal of Physics (2015), 17

We present the stochastic thermodynamics analysis of an open quantum system weakly coupled to multiple reservoirs and driven by a rapidly oscillating external field. The analysis is built on a modified ... [more ▼]

We present the stochastic thermodynamics analysis of an open quantum system weakly coupled to multiple reservoirs and driven by a rapidly oscillating external field. The analysis is built on a modified stochastic master equation in the Floquet basis. Transition rates are shown to satisfy the local detailed balance involving the entropy flowing out of the reservoirs. The first and second law of thermodynamics are also identified at the trajectory level. Mechanical work is identified by means of initial and final projections on energy eigenstates of the system. We explicitly show that this two step measurement becomes unnecessary in the long time limit. A steady-state fluctuation theorem for the currents and rate of mechanical work is also established. This relation does not require the introduction of a time reversed external driving which is usually needed when considering systems subjected to time asymmetric external fields. This is understood as a consequence of the secular approximation applied in consistency with the large time scale separation between the fast driving oscillations and the slower relaxation dynamics induced by the environment. Our results are finally illustrated on a model describing a thermodynamic engine. [less ▲]

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See detailStochastic thermodynamics under coarse graining
Esposito, Massimiliano UL

in Physical Review E (2012), 85(4),

A general formulation of stochastic thermodynamics is presented for open systems exchanging energy and particles with multiple reservoirs. By introducing a partition in terms of “mesostates” (e.g., sets ... [more ▼]

A general formulation of stochastic thermodynamics is presented for open systems exchanging energy and particles with multiple reservoirs. By introducing a partition in terms of “mesostates” (e.g., sets of “microstates”), the consequence on the thermodynamic description of the system is studied in detail. When microstates within mesostates rapidly thermalize, the entire structure of the microscopic theory is recovered at the mesostate level. This is not the case when these microstates remain out of equilibrium, leading to additional contributions to the entropy balance. Some of our results are illustrated for a model of two coupled quantum dots. [less ▲]

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See detailStochastic thermodynamics: A powerful tool to control small systems
Esposito, Massimiliano UL

Scientific Conference (2012, June 01)

Small systems are often subjected to strong fluctuations and can easily be driven far from equilibrium. My aim is to show that stochastic thermodynamics is a powerful theory that can help us better ... [more ▼]

Small systems are often subjected to strong fluctuations and can easily be driven far from equilibrium. My aim is to show that stochastic thermodynamics is a powerful theory that can help us better understand how to manipulate and control small systems in an efficient way. I will discuss in particular how a stochastic driving or a feedback control can be used to make small systems, such as single level quantum dots, operate as efficient thermodynamic machines. [1] M. Esposito, "Stochastic thermodynamics under coarse-graining", Phys. Rev. E 85, 041125 (2012) [2] M. Esposito, N. Kumar, K. Lindenberg and C. Van den Broeck, "Stochastically driven single level quantum dot: a nano-scalefinite-time thermodynamic machine and its various operational modes", Phys. Rev. E 85, 031117 (2012) [3] M. Esposito and G. Schaller, "Stochastic thermodynamics for 'Maxwell demon' feedbacks", arxiv:1204.5671 [less ▲]

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See detailStochastic volatility: approximation and goodness-of-fit test
Gradinaru, Mihai; Nourdin, Ivan UL

in Probability and Mathematical Statistics (2008), 28(1), 1-19

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See detailStochastically driven single-level quantum dot: A nanoscale finite-time thermodynamic machine and its various operational modes
Esposito, Massimiliano UL; Kumar, Niraj; Lindenberg, Katja et al

in Physical Review E (2012), 85(3),

We describe a single-level quantum dot in contact with two leads as a nanoscale finite-time thermodynamic machine. The dot is driven by an external stochastic force that switches its energy between two ... [more ▼]

We describe a single-level quantum dot in contact with two leads as a nanoscale finite-time thermodynamic machine. The dot is driven by an external stochastic force that switches its energy between two values. In the isothermal regime, it can operate as a rechargeable battery by generating an electric current against the applied bias in response to the stochastic driving and then redelivering work in the reverse cycle. This behavior is reminiscent of the Parrondo paradox. If there is a thermal gradient the device can function as a work-generating thermal engine or as a refrigerator that extracts heat from the cold reservoir via the work input of the stochastic driving. The efficiency of the machine at maximum power output is investigated for each mode of operation, and universal features are identified. [less ▲]

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See detailStochastische Analysis
Hackenbroch, Wolfgang; Thalmaier, Anton UL

Book published by Vieweg+Teubner Verlag - Mathematische Leitfäden (1994)

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See detailStoffgeschichte "Die Entführung aus dem Serail" Türkenmusik
Sagrillo, Damien UL

Presentation (1990, July)

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See detailDie stolzesten Grafen sind die Polygraphen
Klump, Rainer UL; Franke, S.

in Baar, L.; Petzina, D. (Eds.) Wirtschaftlicher Strukturwandel, Innovationen und regionaler Wandel im geteilten Deutschland nach 1945 (1999)

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See detailStoner–Wohlfarth model for the anisotropic case
de Campos, Marcos Flavio; da Silva, Fernanda Sampaio; Perigo, Elio Alberto UL et al

in Journal of Magnetism & Magnetic Materials (2013), 345

The Stoner–Wohlfarth (SW) model was calculated for the anisotropic case, by assuming crystallographical texture distributions as Gaussian, Lorentzian and cos n (alpha). All these distributions were tested ... [more ▼]

The Stoner–Wohlfarth (SW) model was calculated for the anisotropic case, by assuming crystallographical texture distributions as Gaussian, Lorentzian and cos n (alpha). All these distributions were tested and both Gaussian and cos n (alpha) give similar results for Mr/Ms above 0.8. However, the use of cosn (alpha) makes it easier to find analytical expressions representing texture.The Lorentzian distribution is a suitable choice for not wel laligned magnets, or magnets with a high fraction of misaligned grains. It is discussed how to obtain the alignment degree Mr/Ms directly from two measurements of magnetic remanence at the transverse and parallel directions to the alignment direction of the magnet .It is demonstrated that even the wel laligned magnets with Mr/Ms=0.96 present coercive field of 60–70% of the anisotropy field, depending on the chosen distribution.The anisotropic SW model was used for discussing hysteresis squareness. Improving the crystalographical texture, the loop squareness also increases. [less ▲]

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See detailStore-operated Ca2+ channels formed by TRPC1, TRPC6 and Orai1 and non-store-operated channels formed by TRPC3 are involved in the regulation of NADPH oxidase in HL-60 granulocytes
Bréchard, Sabrina UL; Melchior, Chantal UL; Plançon, Sébastien UL et al

in Cell Calcium (2008)

Ca(2+) influx has been shown to be essential for NADPH oxidase activity which is involved in the inflammatory process. Ca(2+) conditions underlying the oxidative response are clearly delineated. Here, we ... [more ▼]

Ca(2+) influx has been shown to be essential for NADPH oxidase activity which is involved in the inflammatory process. Ca(2+) conditions underlying the oxidative response are clearly delineated. Here, we show that store-operated Ca(2+) entry (SOCE) is required at the beginning of NADPH oxidase activation in response to fMLF (N-formyl-l-methionyl-l-leucyl-l-phenylalanine ) in neutrophil-like HL-60 cells. When extracellular Ca(2+) is initially removed, early addition of Ca(2+) after stimulation causes a complete restoration of Ca(2+) entry and H(2)O(2) production. Both Ca(2+) entry and H(2)O(2) production are decreased by purported SOCE blockers, 2-aminoethoxydiphenyl borane (2-APB) and SK&F 96365. Endogenously expressed TRPC (transient receptor potential canonical) homologues and Orai1 were investigated for their role in supporting store-operated Ca(2+) channels activity. TRPC1, TRPC6 and Orai1 knock-out by siRNA resulted in the inhibition of Ca(2+) influx and H(2)O(2) production in response to fMLF and thapsigargin while suppression of TRPC3 had no effect on thapsigargin induced-SOCE. 2-APB and SK&F 96365 were able to amplify the reduction of fMLF-stimulated Ca(2+) entry and H(2)O(2) production observed in cells transfected by TRPC3 siRNA. In summary, Ca(2+) influx in HL-60 cells relies on different membrane TRPC channels and Orai1 for allowing NADPH oxidase activation. TRPC3 primarily mediates SOCE-independent pathways and TRPC1, TRPC6 and Orai1 exclusively contribute to SOCE. [less ▲]

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See detailStorytelling at home and at the nursery school: A study of bilingual children’s literacy practices
Kirsch, Claudine UL

in Morys, Nancy; Kirsch, Claudine; Georges, Ingrid (Eds.) et al Lernen und Lehren in multilingualen Kontexten: Zum Umgang mit sprachlich-kultureller Vielfalt im Klassenraum (2014)

Research findings show that high standards in oracy (as well as in literacy) help raise attainment across the curriculum. This paper examines two bilingual children’s practices of storytelling both at ... [more ▼]

Research findings show that high standards in oracy (as well as in literacy) help raise attainment across the curriculum. This paper examines two bilingual children’s practices of storytelling both at nursery school and at home in Luxembourg. The findings reveal some common themes both between the families and between the home and the school settings: storytelling was regular, multimodal and associated with language development. There were also major differences; first, children collaboratively constructed stories at school, where dialogue was valued, but not at home and, second, the adults had a different understanding of multilingualism, which, in turn, impacted on the value they attributed to the children’s opportunities to use languages at school. While the teacher encouraged the bilingual children to draw on their entire linguistic repertoire, one mother would have preferred a monolingual setting. It is hoped that these contextualised findings of cultural practices help practitioners develop linguistically responsive and accountable language teaching. [less ▲]

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See detailStorytelling through a digital shoebox
Lucchesi, Anita UL

Presentation (2017, June 17)

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See detailStout’s unconstrained discourse: Does reason-giving apply across the board?
Burks, Deven UL

Scientific Conference (2017, October)

If considerable scholarly attention has, to this point, focused on the content permitted in Jeffrey Stout’s pragmatist-expressivist account of political discourse and justification as reason-giving, set ... [more ▼]

If considerable scholarly attention has, to this point, focused on the content permitted in Jeffrey Stout’s pragmatist-expressivist account of political discourse and justification as reason-giving, set out in 2004’s Democracy and Tradition, little enough has been said on the scope which he envisions therefor. Can time-consuming and intensely individual reason-giving shape institutional and governmental discourse in the same way as it does face-to-face encounters, associational life and broad-based organizing? While one can concede that unconstrained discourse and appeal to an individual standpoint are appropriate to building consensus and legitimacy in the latter forms, as 2010’s Blessed are the Organized purports to show, one may nonetheless harbour doubts whether public officials could likewise engage in earnest personal narration and exchange of individual perspectives. For, despite the limited number of participants, it remains an open question whether such discourse represents either an appropriate or a practicable way of proceeding in such settings. Indeed, Stout’s own questions, in his 2010 book, as to the efficacy of grassroots groups and broad-based organizing at the state, national or international level, may leave one with the impression that there exists a gap between the individual and associational context and the institutional and governmental. This leaves us with two questions going forwards about unconstrained discourse and the individual standpoint. First, are these different settings sufficiently similar such that Stout’s version of political discourse displaces liberal public reason in institutional and governmental settings? Otherwise, does the former merely complement the latter, contrary to Stout’s assertions? Second, from a systemic point of view, is Stout’s version of public discourse deliberatively net-positive? In other words, as formulated, can it make an important contribution to the balance of the overall deliberative system? If these questions do not admit of an unqualified yes or no, there is reason to suspect that Stout’s account cannot be implemented equally at all levels of political discourse. In the end, we will argue that unconstrained discourse and the individual standpoint, while salutary, are incomplete in themselves and are best suited to a complementary role in institutional and governmental settings as, at most, one tactic among others. [less ▲]

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See detailStrafgesetzlichkeit als völkerstrafrechtliches Legitimationsprinzip
Deffert, Dietmar UL

Doctoral thesis (2007)

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See detailStrafrecht und strafrechtliche Zusammenarbeit in der Europäischen Union
Ligeti, Katalin UL

Book published by Duncker & Humblot (2005)

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