Learning to Race through Coordinate Descent Bayesian Optimisation

In the automation of many kinds of processes, the observable outcome can often be described as the combined effect of an entire sequence of actions, or controls, applied throughout its execution. In these cases, strategies to optimise control policies for individual stages of the process might not be applicable, and instead the whole policy might have to be optimised at once. On the other hand, the cost to evaluate the policy's performance might also be high, being desirable that a solution can be found with as few interactions as possible with the real system. We consider the problem of optimising control policies to allow a robot to complete a given race track within a minimum amount of time. We assume that the robot has no prior information about the track or its own dynamical model, just an initial valid driving example. Localisation is only applied to monitor the robot and to provide an indication of its position along the track's centre axis. We propose a method for finding a policy that minimises the time per lap while keeping the vehicle on the track using a Bayesian optimisation (BO) approach over a reproducing kernel Hilbert space. We apply an algorithm to search more efficiently over high-dimensional policy-parameter spaces with BO, by iterating over each dimension individually, in a sequential coordinate descent-like scheme. Experiments demonstrate the performance of the algorithm against other methods in a simulated car racing environment.Comment: Accepted as conference paper for the 2018 IEEE International Conference on Robotics and Automation (ICRA

Non-perturbative QCD effective charges

Using gluon and ghost propagators obtained from Schwinger-Dyson equations (SDEs), we construct the non-perturbative effective charge of QCD. We employ two different definitions, which, despite their distinct field-theoretic origin, give rise to qualitative comparable results, by virtue of a crucial non-perturbative identity. Most importantly, the QCD charge obtained with either definition freezes in the deep infrared, in agreement with theoretical and phenomenological expectations. The various theoretical ingredients necessary for this construction are reviewed in detail, and some conceptual subtleties are briefly discussed.Comment: Invited talk at Light Cone 2009: Relativistic Nuclear and Particle Physics (LC2009), Sao Jose dos Campos, Brazil, 8-13 July, 200

A mathematical model for controlled drug delivery in swelling polymers

We propose a one-dimensional model to describe the sorption of a solvent by a polymeric membrane, followed by polymer swelling and drug release. We assume that the solvent diffuses into the membrane and induces a stress driven diffusion, that causes a non-Fickian mass flux. We assume that the drug is present in two states (dissolved and undissolved) and that its transport occurs by Fickian diffusion and non-linear dissolution. Polymer swelling is tracked with a volume conservation equation. The system of partial differential equations that define the model is numerically solved. A qualitative analysis of the dependence of the solutions on the parameters of the model shows a complete agreement with the expected physical behavior

Drug Release from Viscoelastic Swelling Polymeric Platforms

We consider a polymeric spherical platform containing a solid dispersed drug that is in contact with a solvent fluid. While swelling, a non-Fickian sorption of the solvent molecules occurs induced by the effect of the viscoelastic properties of the polymer. The solid drug in contact with the solvent fluid dissolves and a Fickian release of dissolved drug takes place. The fluid entrance, the drug dissolution, and the drug release to an external environment are described by a system of PDEs complemented with an equation for the swelling front, initial, and boundary conditions. The model includes the two major factors that govern a swelling process of a polymeric platform within a release medium: the cross-link density and the concentration of the external medium. Energy estimates for the mass of solvent fluid and of undissolved and dissolved drug in the polymeric platform are established. Numerical simulations that illustrate the theoretical results are also included

Problematizações (im)pertinentes : (sobre)vivências das travestis nos serviços de atenção básica em saúde no Brasil

Apresentamos neste artigo algumas discussões a respeito dos corpos nomeados travestis, e seus atravessamentos históricos e sociais, evidenciando as influências discursivas e essencialistas que os inventaram. Pontuaremos brevemente o processo de subjetivação, na qual tanto pode produzir culturas em massas, normalizando e padronizando identidades uniformizadas, como pode singularizá-las, possibilitando novas vivências, experimentações, desejos e prazeres. Em seguida discutiremos sobre o sistema sexo/gênero/sexualidade e a criação da sociedade cisheteronormativa, pontuando que esse sistema nada tem de natural, sendo estrategicamente implantado para manter o poder e sua hegemonia. Nesse sentido, propomos neste artigo, problematizar as violências psicológicas vivenciadas pelas travestis nas instituições públicas de saúde, instituições que em si, deveriam erradicar todo tipo de violência, mas que acabam contribuindo com sua intensificação.We present here some discussions about the appointed bodies transvestites, and its historical and social crossings, emphasizing the discursive and essentialist influences that invented them. Briefly We will briefly outline the process of subjectivation, in which both can produce crops in masses, normalizing and standardizing uniform identities, how can distinguishes them, enabling new experiences, trials, desires and pleasures. Then we will discuss about sex system/gender/sexuality and the creation of heteronormative society, pointing out that this system is not at all natural, being strategically deployed to keep the power and hegemony. In this sense, we propose in this article, discuss the psychological violence experienced by transvestites in public health institutions, institutions which in itself should eradicate all forms of violence, but end up contributing to its intensification

A new look to non-Fickian diffusion

In this paper a non linear mathematical model to describe absorption phenomena in polymers is proposed. The model is established assuming that the diffusing penetrant causes a deformation which induces a viscoelastic stress responsible for a convective field. This convective field is defined to represent an opposition of the polymer to the Fickian diffusion. Several numerical examples show the effectiveness of the model

Social cognition and Theory of Mind: controversies and promises for understanding major psychiatric disorders

The term social cognition generally refers to the mental operations that underlie social interactions including the perception and interpretation of the intentions, dispositions, and behaviors of others and the generation of a response to these behaviors. Social cognition has been considered a valuable and promising field that strives to understand the nature and outcome of major mental disorders. This article discusses the concept of social cognition and its relationship to Theory of Mind (ToM). Theory of Mind in autistic spectrum disorders has been studied since the 1980s, and cognitive impairments in these disorders may be restricted to ToM deficits because other cognitive domains and nonsocial intelligence are preserved. This article addresses the issues of human ontogeny, reviews the main findings from research on schizophrenia and bipolar disorder, and summarizes the tools commonly used in the assessment of these illnesses.Universidade Federal de São Paulo (UNIFESP)Pontifícia Universidade Católica do Rio Grande do SulUNIFESPSciEL

Specific forward/reverse latent heat and martensite fraction measurement during superelastic deformation of nanostructured NiTi wires

International audienceThis study analyses the thermomechanical tensile behaviour of a cold drawn Ti-50.9at.%Ni wire submitted to heat treatment at 598 K for 30 min, which is below the recrystallization temperature (623 K). Such low temperature heat treatment induces a superelastic loop without a stress "plateau". However, the absence or weakness of peaks on its differential scanning calorimetry prevents the determination of specific latent heat. This is a common effect of nanostructured materials such as superelastic wires. A method using strain and temperature field measurements was developed and used to determine thermal power and thermal energy during superelastic tensile tests through a heat balance. From these results and using a thermodynamic approach, forward and reverse specific latent heat and the martensite fraction are estimated as a function of strain and stress

Challenges and technology in the cognitive psychotherapy of childhood ADHD: one-year follow-up of monozygotic twins

The authors describe the follow-up of monozigotic twins treated with cognitive therapy for attention deficit hyperactivity disorder.A escolha do caso deve-se a quatro principais motivos: (1) a alta complexidade do caso dificulta o diagnóstico, a abordagem psicofarmacológica e psicoterápica; (2) as dificuldades logísticas comuns aos profissionais e pacientes do Sistema Único de Saúde (SUS), como dificuldades econômicas e assistenciais, que dificultam o tratamento; (3) a importância da combinação tecnológica de diferentes modelos de terapias cognitivas na abordagem do TDAH, fundamental para alguns casos; (4) e a importância da viabilização proporcionada pelo Programa de Residência quando permite a busca por auxílio externo, em termos de supervisão, o que potencializa a capacitação do residente