196,729 research outputs found
Quantum thermodynamics of strongly coupled driven resonant level models
No full textThe driven resonance level model (a driven molecular level coupled to one or more fermionic baths) has been recently used to study thermodynamic aspects of energy conversion in simple mechanically driven strongly coupled quantum systems. Our original treatment of this problem was based on the non-equilibrium Green function (NEGF) approach[1]. In this talk I will discuss this model using other methodologies that reveal different physical aspects of this problem. First, I will describe an approach[2] based on an expansion of the full system-bath density matrix as a series in powers of the modulation rate, from which the functional form of work, heat, and entropy production rates can be obtained. This approach allows for the inclusion of electron-electron interaction in an approximate way. Second, I repeat the derivation by expressing the density matrix in terms of the asymptotic eigenstates of the system by employing Moller transition operators [3]. The resulting expression, which coincides with results from the steady-state theories of McLean â Zubarev and Hershfield, can reproduce the standard NEGF results for the dot population and the current and, when extended to include driving of the dot energy level and/or the dot-leads coupling, yields the non-adiabatic (second order to the driving speed) corrections to the power, energy and heat production obtained from the NEGF formalism. Using this approach we can easily go beyond the wide band approximation and consider models where the dot is coupled to many leads held at different temperatures and under different chemical potentials. Finally, we employ a numerical solution based on the driven-Liouville-von Neumann approach, which can be used to investigate systems subjected to high driving speeds.
[1] A. Bruch, M. Thomas, S. V. Kusminsky, F. von Oppen and A. Nitzan, Phys. Rev. B, 93, 115318 (2016); M A. Ochoa, A. Bruchand A. Nitzan, Phys. Rev. B 94, 035420 (2016)
[2] W. Dou, M. A. Ochoa,A. Nitzan and J. E. Subotnik, Phys. Rev. B 98, 134306 (2018)
[3] A. Semenov and A. Nitzan, to be published
[4] I. Oz, O. Hod and A. Nitzan, Molecular Physics, in press, and to be published.Non UBCUnreviewedAuthor affiliation: University of PennsylvaniaFacult
Prize Sharing in Collective Contests
No full textThe characteristics of endogenously determined sharing rules and the group-size paradox are studied in a model of group contest with the following features: (i) The prize has mixed private-public good characteristics. (ii) Groups can differ in marginal cost of effort and their membership size. (iii) In each group the members decide how much effort to put without observing the sharing rules of the other groups. It is shown that endogenous determination of group sharing rules completely eliminates the group-size paradox, i.e. a larger group always attains a higher winning probability than a smaller group, unless the prize is purely private. In addition, an interesting pattern of equilibrium group sharing rules is revealed: the group attaining the lower winning probability is the one choosing the rule giving higher incentives to the members.collective contest, mixed public-good prize, endogenous sharing rules, the group-size paradox
Testing the labour theory of value: An exchange
No full textExchange on open letters on the methodologies for testing price value correlations
Quantum transport with two interacting conduction channels
No full textThe transport properties of a conduction junction model characterized by two mutually coupled channels that strongly differ in their couplings to the leads are investigated. Models of this type describe molecular redox junctions (where a level that is weakly coupled to the leads controls the molecular charge, while a strongly coupled one dominates the molecular conduction), and electron counting devices in which the current in a point contact is sensitive to the charging state of a nearby quantum dot. Here we consider the case where transport in the strongly coupled channel has to be described quantum mechanically (covering the full range between sequential tunneling and co-tunneling), while conduction through the weakly coupled channel is a sequential process that could by itself be described by a simple master equation. We compare the result of a full quantum calculation based on the pseudoparticle non-equilibrium Green function method to that obtained from an approximate mixed quantum-classical calculation, where correlations between the channels are taken into account through either the averaged rates or the averaged energy. We find, for the steady state current, that the approximation based on the averaged rates works well in most of the voltage regime, with marked deviations from the full quantum results only at the threshold for charging the weekly coupled level. These deviations are important for accurate description of the negative differential conduction behavior that often characterizes redox molecular junctions in the neighborhood of this threshold. © 2013 AIP Publishing LLC
Eyes Wide Shut: The Ruling Class and the Future of Capitalism
No full textWhat does modern finance tell us about systemic fear and the future of capitalism?
WHEN AND WHERE: November 19, 2010, 6:00-7:30pm || Bell Hall, Harvard Kennedy School of Government || 79 John F. Kennedy Street, Cambridge, M
Politics of Randomness
No full textThe main drawback of the public-policy contest is that the notion of contest success function, a crucial component of the contest model, does not have micro-foundations and, therefore, the random behavior of the government seems ad-hoc. In the present paper we propose a partial micro-foundation for the public-policy contest. The possible rationalization of random government behavior is illustrated in the case of the all-pay auction and Tullock's lottery logit functions. We also clarify how stake asymmetry, lobbying-skill asymmetry and return to lobbying effort determine the relative desirability, from the government's point of view, of these CSFsinterest groups, policy makers, lobbying, public-policy contests, contest success function, rationalization of random government's behavior
A combined microfluidic/dielectrophoretic microorganism concentrator
No full textThesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.Includes bibliographical references (p. 71-72).This thesis presents the development of a high-throughput microfluidic microorganism concentrator for pathogen detection applications. Interdigitated electrodes lining the bottom of the channel use positive dielectrophoretic forces to trap particles. A passive mixer is used to circulate the liquid in the channel, transporting particles to within the trapping region of the electrodes. Samples are extracted and their concentrations measured using a spectrophotometer. Concentration enhancements up to 40x at 500 gl/min flowrate using polystyrene microspheres and up to 10x at 100 gll/min flowrate using B. subtilis spores are achieved.by Nitzan Gadish.M.Eng
Saying It Through The Maternal Body: understanding maternal subjectivity through art practice
No full textIn referring to psychoanalyst and theorist Julia Kristeva?s claim that the maternal body has no subject, this research aimed at finding answers to the following question: in what ways might a maternal subjectivity be understood through art practice? The research focused on three themes: fragmentation, invisibility and boundaries. Initially, these themes were researched in the context of the maternal body and the abject. The engagement with the maternal body has led to expanding the inquiry to include kibbutz childhood memory, in general, and bodily memories, in particular. This has led to revealing a childhood trauma. It was established that fragmentation, invisibility and questions of boundaries are rooted in trauma. Trauma has been further explored, to be revealed as a sequence of traumas, including the Israeli-Palestinian conflict and intergenerational trauma, which span private and public spheres. The methodology research in action has been developed through the use of the „observer-participant? position, as well as the methods of persona and performative acts. Installation has been developed as a shared space, where traumatic memory has been re-visited and audience became witness. The research contributes to new knowledge in the field of trauma, in the contexts of maternal subjectivity, kibbutz childhood and the Israeli-Palestinian conflict. The text provides a critical reflection for the practice, both construct this research
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