The controversial piston in the thermodynamic limit

We consider the evolution of a system composed of $N$ non-interacting point particles of mass $m$ in a container divided in two regions by a movable adiabatic wall (adiabatic piston). In this talk we discuss the thermodynamic limit where the area $A$ of the container, the number $N$ of particles, and the mass $M$ of the piston go to infinity keeping $\frac{A}M$ and $\frac{N}M$ fixed. We show that in this limit the motion of the piston is deterministic. Introducing simplifying assumptions we discuss the approach to equilibrium and we illustrate the results with numerical simulations. The comparison with the case of a system with finite $(A, N, M)$ will be presented. We consider the evolution of a system composed of $N$ non-interacting point particles of mass $m$ in a container divided in two regions by a movable adiabatic wall (adiabatic piston). In this talk we discuss the thermodynamic limit where the area $A$ of the container, the number $N$ of particles, and the mass $M$ of the piston go to infinity keeping $\frac{A}M$ and $\frac{N}M$ fixed. We show that in this limit the motion of the piston is deterministic. Introducing simplifying assumptions we discuss the approach to equilibrium and we illustrate the results with numerical simulations. The comparison with the case of a system with finite $(A, N, M)$ will be presented.Comment: 7 pages, 3 figures, submitted to Physica

Yaw Rate and Sideslip Angle Control Through Single Input Single Output Direct Yaw Moment Control

Electric vehicles with independently controlled drivetrains allow torque vectoring, which enhances active safety and handling qualities. This article proposes an approach for the concurrent control of yaw rate and sideslip angle based on a single-input single-output (SISO) yaw rate controller. With the SISO formulation, the reference yaw rate is first defined according to the vehicle handling requirements and is then corrected based on the actual sideslip angle. The sideslip angle contribution guarantees a prompt corrective action in critical situations such as incipient vehicle oversteer during limit cornering in low tire-road friction conditions. A design methodology in the frequency domain is discussed, including stability analysis based on the theory of switched linear systems. The performance of the control structure is assessed via: 1) phase-plane plots obtained with a nonlinear vehicle model; 2) simulations with an experimentally validated model, including multiple feedback control structures; and 3) experimental tests on an electric vehicle demonstrator along step steer maneuvers with purposely induced and controlled vehicle drift. Results show that the SISO controller allows constraining the sideslip angle within the predetermined thresholds and yields tire-road friction adaptation with all the considered feedback controllers

True happiness: The role of morality in the folk concept of happiness

Recent scientific research has settled on a purely descriptive definition of happiness that is focused solely on agents’ psychological states (high positive affect, low negative affect, high life satisfaction). In contrast to this understanding, recent research has suggested that the ordinary concept of happiness is also sensitive to the moral value of agents’ lives. Five studies systematically investigate and explain the impact of morality on ordinary assessments of happiness. Study 1 demonstrates that moral judgments influence assessments of happiness not only for untrained participants, but also for academic researchers and even in those who study happiness specifically. Studies 2 and 3 then respectively ask whether this effect may be explained by general motivational biases or beliefs in a just world. In both cases, we find evidence against these explanations. Study 4 shows that the impact of moral judgments cannot be explained by changes in the perception of descriptive psychological states. Finally, Study 5 compares the impact of moral and non-moral value, and provides evidence that unlike non-moral value, moral value is part of the criteria that govern the ordinary concept of happiness. Taken together, these studies provide a specific explanation of how and why the ordinary concept of happiness deviates from the definition used by researchers studying happiness

On the Second Law of thermodynamics and the piston problem

The piston problem is investigated in the case where the length of the cylinder is infinite (on both sides) and the ratio $m/M$ is a very small parameter, where $m$ is the mass of one particle of the gaz and $M$ is the mass of the piston. Introducing initial conditions such that the stochastic motion of the piston remains in the average at the origin (no drift), it is shown that the time evolution of the fluids, analytically derived from Liouville equation, agrees with the Second Law of thermodynamics. We thus have a non equilibrium microscopical model whose evolution can be explicitly shown to obey the two laws of thermodynamics.Comment: 29 pages, 9 figures submitted to Journal of Statistical Physics (2003

Constraint on Cosmic Density of the String Moduli Field in Gauge-Mediated Supersymmetry-Breaking Theories

We derive a constraint on the cosmic density of string moduli fields in gauge-mediated supersymmetry-breaking theories by requiring that photons emitted from the unstable moduli fields should not exceed the observed X-ray backgrounds. Since mass of the moduli field lies in the range between $O(0.1)$keV and $O(1)$MeV and the decay occurs through a gravitational interaction, the lifetime of the moduli field is much longer than the age of the present universe. The obtained upperbound on their cosmic density becomes more stringent than that from the unclosure condition for the present universe for the mass greater than about 100keV.Comment: 7 pages, a LaTeX2e file and two postscript figure

"Blocos regionais de ABS": como a tecnologia blockchain pode possibilitar uma solução regional para situações transfronteiriças

The evolution of consumption habits, in search of more natural products, increasingly requires the use of genetic resources to satisfy the demands of society. Considering that many of these resources come from transboundary species and that access to them and their use in research and technological development is primarily regulated by international ABS regimes, the article exposes some of the limits of international standards, especially the Nagoya Protocol, when dealing with these situations in particular, identifying the intention in the elaboration of the regimes. Based on this analysis, a regional solution is proposed, allied to the existing trend towards the elaboration of norms at this level of governance, in order to ensure the effectiveness of the regimes. To implement this solution, the use of blockchain technology is suggested to create distributed platforms that can serve different countries, traditional peoples and users involved in activities with genetic resources and associated traditional knowledge. The technology allows for greater transparency, traceability and decentralization of data, in addition to allowing automation and cost reduction of several operations, among other attributes, although it is not free of limits, challenges and criticisms.A evolução dos hábitos de consumo, em busca de produtos mais naturais, exige cada vez mais o uso de recursos genéticos para satisfazer as demandas da sociedade. Considerando que muitos desses recursos são provenientes de espécies transfronteiriças e que o acesso a elas e seu emprego em pesquisa e desenvolvimento tecnológico é regulado primeiramente pelos regimes internacionais de ABS, o presente artigo expõe alguns dos limites das normas internacionais, em especial do Protocolo de Nagoya, ao tratar dessas situações em particular, identificando a intenção na elaboração dos regimes. A partir dessa análise, propõe-se uma solução regional, aliada a existente tendência de elaboração de normas nesse nível de governança, a fim de assegurar a efetividade dos regimes. Para a instrumentalização dessa solução, sugere-se a utilização da tecnologia blockchain na criação de plataformas distribuídas, que possam atender aos diversos países, povos tradicionais e usuários envolvidos nas atividades com recursos genéticos e conhecimentos tradicionais associados. A tecnologia permite garantir maior transparência, rastreabilidade e descentralização de dados, além de permitir a automatização e a redução de custos de várias operações, dentre outros atributos, ainda que não esteja isenta de limites, desafios e críticas.info:eu-repo/semantics/publishedVersio

Social network analysis shows direct evidence for social transmission of tool use in wild chimpanzees

The authors are grateful to the Royal Zoological Society of Scotland for providing core funding for the Budongo Conservation Field Station. The fieldwork of CH was funded by the Leverhulme Trust, the Lucie Burgers Stichting, and the British Academy. TP was funded by the Canadian Research Chair in Continental Ecosystem Ecology, and received computational support from the Theoretical Ecosystem Ecology group at UQAR. The research leading to these results has received funding from the People Programme (Marie Curie Actions) and from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007–2013) REA grant agreement n°329197 awarded to TG, ERC grant agreement n° 283871 awarded to KZ. WH was funded by a BBSRC grant (BB/I007997/1).Social network analysis methods have made it possible to test whether novel behaviors in animals spread through individual or social learning. To date, however, social network analysis of wild populations has been limited to static models that cannot precisely reflect the dynamics of learning, for instance, the impact of multiple observations across time. Here, we present a novel dynamic version of network analysis that is capable of capturing temporal aspects of acquisition-that is, how successive observations by an individual influence its acquisition of the novel behavior. We apply this model to studying the spread of two novel tool-use variants, "moss-sponging'' and "leaf-sponge re-use,'' in the Sonso chimpanzee community of Budongo Forest, Uganda. Chimpanzees are widely considered the most "cultural'' of all animal species, with 39 behaviors suspected as socially acquired, most of them in the domain of tool-use. The cultural hypothesis is supported by experimental data from captive chimpanzees and a range of observational data. However, for wild groups, there is still no direct experimental evidence for social learning, nor has there been any direct observation of social diffusion of behavioral innovations. Here, we tested both a static and a dynamic network model and found strong evidence that diffusion patterns of moss-sponging, but not leaf-sponge re-use, were significantly better explained by social than individual learning. The most conservative estimate of social transmission accounted for 85% of observed events, with an estimated 15-fold increase in learning rate for each time a novice observed an informed individual moss-sponging. We conclude that group-specific behavioral variants in wild chimpanzees can be socially learned, adding to the evidence that this prerequisite for culture originated in a common ancestor of great apes and humans, long before the advent of modern humans.Publisher PDFPeer reviewe

Uniform existence of the integrated density of states for random Schr\"odinger operators on metric graphs over Zd\mathbb{Z}^d

We consider ergodic random magnetic Schr\"odinger operators on the metric graph $\mathbb{Z}^d$ with random potentials and random boundary conditions taking values in a finite set. We show that normalized finite volume eigenvalue counting functions converge to a limit uniformly in the energy variable. This limit, the integrated density of states, can be expressed by a closed Shubin-Pastur type trace formula. It supports the spectrum and its points of discontinuity are characterized by existence of compactly supported eigenfunctions. Among other examples we discuss percolation models.Comment: 17 pages; typos removed, references updated, definition of subgraph densities explaine