Identifying Functional Thermodynamics in Autonomous Maxwellian Ratchets

We introduce a family of Maxwellian Demons for which correlations among information bearing degrees of freedom can be calculated exactly and in compact analytical form. This allows one to precisely determine Demon functional thermodynamic operating regimes, when previous methods either misclassify or simply fail due to approximations they invoke. This reveals that these Demons are more functional than previous candidates. They too behave either as engines, lifting a mass against gravity by extracting energy from a single heat reservoir, or as Landauer erasers, consuming external work to remove information from a sequence of binary symbols by decreasing their individual uncertainty. Going beyond these, our Demon exhibits a new functionality that erases bits not by simply decreasing individual-symbol uncertainty, but by increasing inter-bit correlations (that is, by adding temporal order) while increasing single-symbol uncertainty. In all cases, but especially in the new erasure regime, exactly accounting for informational correlations leads to tight bounds on Demon performance, expressed as a refined Second Law of Thermodynamics that relies on the Kolmogorov-Sinai entropy for dynamical processes and not on changes purely in system configurational entropy, as previously employed. We rigorously derive the refined Second Law under minimal assumptions and so it applies quite broadly---for Demons with and without memory and input sequences that are correlated or not. We note that general Maxwellian Demons readily violate previously proposed, alternative such bounds, while the current bound still holds.Comment: 13 pages, 9 figures, http://csc.ucdavis.edu/~cmg/compmech/pubs/mrd.ht

The Employer Approach to Industrial Relations Research

L'auteur ne prétend pas exposer ici le point de vue des employeurs en général, mais plutôt celui d'un homme de recherche, sur l'attitude la plus appropriée qu'un employeur devrait avoir envers les recherches en relations industrielles. Cet intérêt s'étend à tous les aspects des relations ouvrières et inclut l'exécution du travail, ses effets sur l'ouvrier, les rapports entre individus et ceux entre l'individu et le groupe.L'employeur doit se préoccuper de la relation entre la technologie et les valeurs humaines. Pour répondre à ce besoin les chercheurs doivent donc se demander « quelles sont les valeurs dominantes » et « comment la technologie peut mieux servir ces valeurs ? »Les valeurs dominantes traditionnelles étaient économiques. Mais grâce à la technologie, l'industrie a maintenant résolu le problème de la pénurie Ceci s'est malheureusement fait aux dépens de l'aspect social et psychologique. C'est pourquoi le public est de plus en plus mécontent du fait qu'on néglige d'autres valeurs, comme la santé publique et la sécurité sociale, les aspects agréables du milieu et la satisfaction des employés à leur lieu de travail ainsi qu'à l'extérieur. Les recherches doivent donc aider l'employeur à découvrir les valeurs dirigeantes appropriées.En ce qui concerne la seconde question, la technologie par rapport aux valeurs humaines, elle peut être considérée au niveau de l'individu, de l'organisation ou de la société. Au niveau de l'individu l'implication du changement est une sphère grandement négligée. On tend à rendre les gens incapable de s'adapter au changement, en les forçant à demeurer dans un emploi restreint pour plusieurs années jusqu'à ce que le travail devienne inutile. Et quand les individus ont perdu la plus grande partie de leur capacité d'apprendre, on essaie de les ré-entraîner pour un nouvel emploi. Mais il est alors trop tard. Nous devons orienter nos recherches sur les façons de maintenir et de développer le potentiel dans chaque être, avec une expérience adéquatement variée et une éducation permanente, tout en maintenant les gens au travail.La hiérarchie de nos organisations crée une scission horizontale entre la direction et les subordonnés qui en plus est agrandie par la présence des syndicats. Des scissions verticales se produisent aussi à cause de l'identification d'objectifs départementaux et de rivalités inter-départementales. Ainsi est sabordé le flux des communications essentiel au bon fonctionnement et dissipée la motivation à atteindre des buts communs. De nouvelles formes d'organisation doivent être mises à l'essai afin de déterminer la meilleure méthode d'application à différents champs d'activité.Les effets de l'industrie sur la société en général sont grandement répandus et sont simplement esquissés ici. On constate généralement de nos jours que la nature peu satisfaisante de leur travail et l'amélioration restreinte qu'on y a apportée ont rendu beaucoup d'employés apathiques, hostiles et dépendants. La publicité continuelle de l'industrie a créé l'idée que les possessions matérielles sont synonymes de bien-être. On a ainsi encouragé un groupe nouveau à exiger les produits matériels que l'on manufacture. On a donc contribué à créer des dissensions dans la société et des conflits chez l'individu.L'industrie a permis de grandes améliorations dans le domaine matériel, mais cela aux dépens du bien-être social et psychologique de l'individu. Les recherches en relations industrielles doivent aider le plus possible l'employeur à améliorer la société, en tenant compte davantage de la portée des valeurs humaines, e.g. le développement satisfaisant de l'individu. Ce chemin conduit à une véritable civilisation.In his article, the author shall emphazise that the managers role is to relate technology to human values. Traditionally, the governing value has been productivity in the economic sense. He shall suggest that a wider range of human values must be supported, e.g. the satisfying growth of the individual employee

QCD Thermodynamics with Improved Actions

The thermodynamics of the SU(3) gauge theory has been analyzed with tree level and tadpole improved Symanzik actions. A comparison with the continuum extrapolated results for the standard Wilson action shows that improved actions lead to a drastic reduction of finite cut-off effects already on lattices with temporal extent $N_\tau=4$. Results for the pressure, the critical temperature, surface tension and latent heat are presented. First results for the thermodynamics of four-flavour QCD with an improved staggered action are also presented. They indicate similarly large improvement factors for bulk thermodynamics.Comment: Talk presented at LATTICE96(finite temperature) 4 pages, LaTeX2e file, 6 eps-file

Shortcuts to Thermodynamic Computing: The Cost of Fast and Faithful Erasure

Landauer's Principle states that the energy cost of information processing must exceed the product of the temperature and the change in Shannon entropy of the information-bearing degrees of freedom. However, this lower bound is achievable only for quasistatic, near-equilibrium computations -- that is, only over infinite time. In practice, information processing takes place in finite time, resulting in dissipation and potentially unreliable logical outcomes. For overdamped Langevin dynamics, we show that counterdiabatic potentials can be crafted to guide systems rapidly and accurately along desired computational paths, providing shortcuts that allows for the precise design of finite-time computations. Such shortcuts require additional work, beyond Landauer's bound, that is irretrievably dissipated into the environment. We show that this dissipated work is proportional to the computation rate as well as the square of the information-storing system's length scale. As a paradigmatic example, we design shortcuts to erase a bit of information metastably stored in a double-well potential. Though dissipated work generally increases with erasure fidelity, we show that it is possible perform perfect erasure in finite time with finite work. We also show that the robustness of information storage affects the energetic cost of erasure---specifically, the dissipated work scales as the information lifetime of the bistable system. Our analysis exposes a rich and nuanced relationship between work, speed, size of the information-bearing degrees of freedom, storage robustness, and the difference between initial and final informational statistics.Comment: 19 pages, 7 figures; http://csc.ucdavis.edu/~cmg/compmech/pubs/scte.ht

Implementation of a local principal curves algorithm for neutrino interaction reconstruction in a liquid argon volume

A local principal curve algorithm has been implemented in three dimensions for automated track and shower reconstruction of neutrino interactions in a liquid argon time projection chamber. We present details of the algorithm and characterise its performance on simulated data sets.Comment: 14 pages, 17 figures; typing correction to Eq 5, the definition of the local covariance matri

Spending time with money: from shared values to social connectivity

This article has been made available through the Brunel Open Access Publishing Fund.There is a rapidly growing momentum driving the development of mobile payment systems for co-present interactions, using near-field communication on smartphones and contactless payment systems. The design (and marketing) imperative for this is to enable faster, simpler, effortless and secure transactions, yet our evidence shows that this focus on reducing transactional friction may ignore other important features around making payments. We draw from empirical data to consider user interactions around financial exchanges made on mobile phones. Our findings examine how the practices around making payments support people in making connections, to other people, to their communities, to the places they move through, to their environment, and to what they consume. While these social and community bonds shape the kinds of interactions that become possible, they also shape how users feel about, and act on, the values that they hold with their co-users. We draw implications for future payment systems that make use of community connections, build trust, leverage transactional latency, and generate opportunities for rich social interactions

Effects of Line-tying on Resistive Tearing Instability in Slab Geometry

The effects of line-tying on resistive tearing instability in slab geometry is studied within the framework of reduced magnetohydrodynamics (RMHD).\citep{KadomtsevP1974,Strauss1976} It is found that line-tying has a stabilizing effect. The tearing mode is stabilized when the system length $L$ is shorter than a critical length $L_{c}$, which is independent of the resistivity $\eta$. When $L$ is not too much longer than $L_{c}$, the growthrate $\gamma$ is proportional to $\eta$ . When $L$ is sufficiently long, the tearing mode scaling $\gamma\sim\eta^{3/5}$ is recovered. The transition from $\gamma\sim\eta$ to $\gamma\sim\eta^{3/5}$ occurs at a transition length $L_{t}\sim\eta^{-2/5}$.Comment: Correct a typ

Spectral methods for the wave equation in second-order form

Current spectral simulations of Einstein's equations require writing the equations in first-order form, potentially introducing instabilities and inefficiencies. We present a new penalty method for pseudo-spectral evolutions of second order in space wave equations. The penalties are constructed as functions of Legendre polynomials and are added to the equations of motion everywhere, not only on the boundaries. Using energy methods, we prove semi-discrete stability of the new method for the scalar wave equation in flat space and show how it can be applied to the scalar wave on a curved background. Numerical results demonstrating stability and convergence for multi-domain second-order scalar wave evolutions are also presented. This work provides a foundation for treating Einstein's equations directly in second-order form by spectral methods.Comment: 16 pages, 5 figure

Analytical model of brittle destruction based on hypothesis of scale similarity

The size distribution of dust particles in nuclear fusion devices is close to the power function. A function of this kind can be the result of brittle destruction. From the similarity assumption it follows that the size distribution obeys the power law with the exponent between -4 and -1. The model of destruction has much in common with the fractal theory. The power exponent can be expressed in terms of the fractal dimension. Reasonable assumptions on the shape of fragments concretize the power exponent, and vice versa possible destruction laws can be inferred on the basis of measured size distributions.Comment: 10 pages, 3 figure