2,821 research outputs found

    Ion-induced nucleation. II. Polarizable multipolar molecules

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    Density functional theory is applied to ion-induced nucleation of polarizable multipolar molecules. The asymmetric nature of the ion-molecule interaction is shown to cause the sign preference in ion-induced nucleation. When the ion-molecule interaction is weak, the observed sign preference is consistent with that of the bare ion-molecule interaction potential and decreases with increasing supersaturation. However, as the ion-molecule interaction becomes stronger, the sign preference in the reversible work exhibits some nontrivial behavior. For molecular parameters applicable for CS2 and CH4, the predicted values of the reversible work of nucleation depend on the sign of the ion charge, yielding a difference in the nucleation rate by factors of 10 to 10^(2) and 10 to 10^(5), respectively

    De Branges spaces and Krein's theory of entire operators

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    This work presents a contemporary treatment of Krein's entire operators with deficiency indices (1,1)(1,1) and de Branges' Hilbert spaces of entire functions. Each of these theories played a central role in the research of both renown mathematicians. Remarkably, entire operators and de Branges spaces are intimately connected and the interplay between them has had an impact in both spectral theory and the theory of functions. This work exhibits the interrelation between Krein's and de Branges' theories by means of a functional model and discusses recent developments, giving illustrations of the main objects and applications to the spectral theory of difference and differential operators.Comment: 37 pages, no figures. The abstract was extended. Typographical errors were corrected. The bibliography style was change

    Hardy's proof of nonlocality in the presence of noise

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    We extend the validity of Hardy's nonlocality without inequalities proof to cover the case of special one-parameter classes of non-pure statistical operators. These mixed states are obtained by mixing the Hardy states with a completely chaotic noise or with a colored noise and they represent a realistic description of imperfect preparation processes of (pure) Hardy states in nonlocality experiments. Within such a framework we are able to exhibit a precise range of values of the parameter measuring the noise affecting the non-optimal preparation of an arbitrary Hardy state, for which it is still possible to put into evidence genuine nonlocal effects. Equivalently, our work exhibits particular classes of bipartite mixed states whose constituents do not admit any local and deterministic hidden variable model reproducing the quantum mechanical predictions.Comment: 9 pages, 2 figures, RevTex, revised versio

    Ontological Relativity reconsidered: Quine on Löwenheim-Skolem, Davidson on Quine

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    In view of the dramatic contrast between speculative thought dressed in fashionable jargon and Quine's sober accounts of the scientific status quo it might seem frivolous even to suggest that his work exhibits a postmodern touch. The present paper will, nevertheless, focus on Quine's usage of the Löwenheim-Skolem theorems as a prominent example of ontological relativity and will attempt to show that Quine's treatment is unattractive to philosophers of mathematics and -- more generally -- untenable within the very methodology arising from Quine's basic approach. After examining the doctrine of relativity as applied to the Löwenheim-Skolem result two recent reflections on it's theoretical impact will be discussed. Those contributions make a strong case against the kind of attitude exemplified by Quine, but they do not address the general issue of how to deal with relativism. Donald Davidson has provided a remarkably attractive strategy to counter relativistic moves. Stripping away postmodernist pretensions this strategy challenges the peculiar Quinean mix of methodological austerity and anti-foundationalism

    Distributed Learning over Unreliable Networks

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    Most of today's distributed machine learning systems assume {\em reliable networks}: whenever two machines exchange information (e.g., gradients or models), the network should guarantee the delivery of the message. At the same time, recent work exhibits the impressive tolerance of machine learning algorithms to errors or noise arising from relaxed communication or synchronization. In this paper, we connect these two trends, and consider the following question: {\em Can we design machine learning systems that are tolerant to network unreliability during training?} With this motivation, we focus on a theoretical problem of independent interest---given a standard distributed parameter server architecture, if every communication between the worker and the server has a non-zero probability pp of being dropped, does there exist an algorithm that still converges, and at what speed? The technical contribution of this paper is a novel theoretical analysis proving that distributed learning over unreliable network can achieve comparable convergence rate to centralized or distributed learning over reliable networks. Further, we prove that the influence of the packet drop rate diminishes with the growth of the number of \textcolor{black}{parameter servers}. We map this theoretical result onto a real-world scenario, training deep neural networks over an unreliable network layer, and conduct network simulation to validate the system improvement by allowing the networks to be unreliable

    Landau thermodynamic potential for BaTiO_3

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    In the paper, the description of the dielectric and ferroelectric properties of BaTiO_3 single crystals using Landau thermodynamic potential is addressed. Our results suggest that when using the sixth-power free energy expansion of the thermodynamic potential, remarkably different values of the fourth-power coefficient, \beta (the coefficient of P^4_i terms), are required to adequately reproduce the nonlinear dielectric behavior of the paraelectric phase and the electric field induced ferroelectric phase, respectively. In contrast, the eighth-power expansion with a common set of coefficients enables a good description for both phases at the same time. These features, together with the data available in literature, strongly attest to the necessity of the eighth-power terms in Landau thermodynamic potential of BaTiO_3. In addition, the fourth-power coefficients, \beta and \xi (the coefficient of P^2_i P^2_j terms), were evaluated from the nonlinear dielectric responses along [001], [011], and [111] orientations in the paraelectric phase. Appreciable temperature dependence was evidenced for both coefficients above T_C. Further analysis on the linear dielectric response of the single domain crystal in the tetragonal phase demonstrated that temperature dependent anharmonic coefficients are also necessary for an adequate description of the dielectric behavior in the ferroelectric phase. As a consequence, an eighth-power thermodynamic potential, with some of the anharmonic coefficients being temperature dependent, was proposed and compared with the existing potentials. In general, the potential proposed in this work exhibits a higher quality in reproducing the dielectric and ferroelectric properties of this prototypic ferroelectric substance.Comment: 7 figures, 5 table

    A temperature independent driver for Mach-Zehnder modulators

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    This paper describes a fully differential inductorlesstemperature independent laser driver for a Mach-Zehndermodulator (MZM). The laser driver in this work exhibits robustnessin bandwidth and gain across the temperature range27oC to 135oC. This driver (fabricated using a 130nm CMOSprocess) can achieve a differential output voltage swing of up to4Vpp when driving a 50 Ohm Load at speeds of up to 12.5Gb/sacross a temperature range 27oC to 135oC

    HYPERPROPERTIES-BASED OPTICAL FLOW-BASED AUTONOMOUS DRIVING SYSTEM

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    This study presents an autonomous driving system based on the principles of trace vectors derived from hyperproperty of a modified optical flowalgorithm. This technique allows keeping track of the past motion vectors by tracking the constraint sets to overcome the non-linear attributes ofthe deformable feature points and motion vectors. The results presented in this work exhibits stable tracking and multi-step prediction in a limitednumber of steps with less training vectors

    Dayton Athletic Department: Creative Services Project

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    During my role as the Athletic Department’s Creative Services Intern, I worked along side the Assistant Creative Director. I helped the Assistant Creative Director specifically with Graphic Design for Dayton’s Winter and Spring sports teams. I assisted with the creation of print and digital collateral utilizing InDesign, Photoshop, and Illustrator. I helped creating marketing fliers, game programs, and game day video board graphics. I also helped design for social media accounts including Facebook, Twitter and Instagram. This work exhibits what I accomplished the past several months.https://ecommons.udayton.edu/stander_posters/1993/thumbnail.jp
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