Density profiles in the raise and peel model with and without a wall; physics and combinatorics

We consider the raise and peel model of a one-dimensional fluctuating interface in the presence of an attractive wall. The model can also describe a pair annihilation process in disordered unquenched media with a source at one end of the system. For the stationary states, several density profiles are studied using Monte Carlo simulations. We point out a deep connection between some profiles seen in the presence of the wall and in its absence. Our results are discussed in the context of conformal invariance ( c = 0 theory). We discover some unexpected values for the critical exponents, which are obtained using combinatorial methods. We have solved known ( Pascal`s hexagon) and new (split-hexagon) bilinear recurrence relations. The solutions of these equations are interesting in their own right since they give information on certain classes of alternating sign matrices.

A conformal invariant growth model

We present a one-parameter extension of the raise and peel one-dimensional growth model. The model is defined in the configuration space of Dyck (RSOS) paths. Tiles from a rarefied gas hit the interface and change its shape. The adsorption rates are local but the desorption rates are non-local; they depend not only on the cluster hit by the tile but also on the total number of peaks (local maxima) belonging to all the clusters of the configuration. The domain of the parameter is determined by the condition that the rates are non-negative. In the finite-size scaling limit, the model is conformal invariant in the whole open domain. The parameter appears in the sound velocity only. At the boundary of the domain, the stationary state is an adsorbing state and conformal invariance is lost. The model allows us to check the universality of non-local observables in the raise and peel model. An example is given.

A pattern recognition approach to complex networks

Complex networks exist in many areas of science such as biology, neuroscience, engineering, and sociology. The growing development of this area has led to the introduction of several topological and dynamical measurements, which describe and quantify the structure of networks. Such characterization is essential not only for the modeling of real systems but also for the study of dynamic processes that may take place in them. However, it is not easy to use several measurements for the analysis of complex networks, due to the correlation between them and the difficulty of their visualization. To overcome these limitations, we propose an effective and comprehensive approach for the analysis of complex networks, which allows the visualization of several measurements in a few projections that contain the largest data variance and the classification of networks into three levels of detail, vertices, communities, and the global topology. We also demonstrate the efficiency and the universality of the proposed methods in a series of real-world networks in the three levels.

On exact time averages of a massive Poisson particle

In this work we study, under the Stratonovich definition, the problem of the damped oscillatory massive particle subject to a heterogeneous Poisson noise characterized by a rate of events, lambda(t), and a magnitude, Phi, following an exponential distribution. We tackle the problem by performing exact time averages over the noise in a similar way to previous works analysing the problem of the Brownian particle. From this procedure we obtain the long-term equilibrium distributions of position and velocity as well as analytical asymptotic expressions for the injection and dissipation of energy terms. Considerations on the emergence of stochastic resonance in this type of system are also set forth.

Cellular automaton model for molecular traffic jams

We consider the time evolution of an exactly solvable cellular automaton with random initial conditions both in the large-scale hydrodynamic limit and on the microscopic level. This model is a version of the totally asymmetric simple exclusion process with sublattice parallel update and thus may serve as a model for studying traffic jams in systems of self-driven particles. We study the emergence of shocks from the microscopic dynamics of the model. In particular, we introduce shock measures whose time evolution we can compute explicitly, both in the thermodynamic limit and for open boundaries where a boundary-induced phase transition driven by the motion of a shock occurs. The motion of the shock, which results from the collective dynamics of the exclusion particles, is a random walk with an internal degree of freedom that determines the jump direction. This type of hopping dynamics is reminiscent of some transport phenomena in biological systems.

O orçamento como instrumento de planejamento, execução e controle: estudo de caso do plano diretor da Marinha do Brasil

O objetivo deste estudo é verificar o Plano Diretor, instrumento de planejamento, execução e controle das ações desenvolvidas pela Marinha do Brasil, está adequado à ambiência vislumbrada para o século XXI. De forma sistêmica, é construído o referencial teórico sobre assuntos pertinentes ao problema a ser investigado, tais como Teoria da decisão, Teoria orçamentária, gestão estratégica e modelos teóricos de sistemas de planejamento e controle. O resultado da análise das características do sistema e do processo do Plano Diretor indica haver pontos passíveis de serem aperfeiçoados. Ao final, é oferecido um resumo de sugestões de medidas para tornar o Plano Diretor um instrumento up-to-date de gestão orçamentária.

A confusão no processo de escolha do consumidor

Dentro da literatura de Comportamento do Consumidor e Teoria da Decisão existe considerável corpo teórico que analisa sentimentos negativos e reações adversas no processo decisório de compras de produtos de alto e baixo envolvimento. Vários fenômenos são identificados como negativos no processo, principalmente a Confusão do Consumidor, que compreende três dimensões: i) muitas informações similares sobre produtos, ii) muitas informações sobre diferentes produtos e iii) informações falsas e ambíguas. Tal fenômeno, no entanto, parece ser moderado por um conjunto de variáveis, como o Envolvimento, a Experiência e a Restrição de Tempo (moderadoras da relação entre Confusão do Consumidor e Intenção de Compra). Este fato foi identificado através de entrevistas em profundidade. Os resultados das entrevistas permitiram identificar as variáveis moderadoras, assim como a existência do fenômeno e sua relação com a decisão final de compra. Na segunda fase da pesquisa, supõe-se que indivíduos com baixo Envolvimento e Restrição de Tempo possuam uma propensão maior à confusão. No Estudo 2 foram utilizados como moderadores o Envolvimento e a Restrição de Tempo, ambos manipulados por instrução, sendo as variáveis dependentes a Intenção de Compra e a Confusão do Consumidor. Os resultados do Estudo 2 permitiram inferir que existem diferenças significativas entre os grupos, quando analisada a variável Confusão do Consumidor, mas, em alguns grupos, a Intenção de Compra não era significativamente diferente. No Estudo 3 foram manipuladas a Experiência (forte e fraca) e a Confusão do Consumidor, sendo a variável dependente a Intenção de Compra. Os resultados do Estudo 3 também permitiram inferir que existem diferenças significativas entre os grupos na Intenção de compra, quando consideradas baixa ou alta confusão, assim como Experiência forte ou fraca. Na última fase da pesquisa foram destacadas as estratégias dos consumidores para lidar com o fenômeno Confusão do Consumidor. Tais estratégias, muitas vezes, são mediadoras de comportamentos posteriores, como a compra do produto. No Estudo 4 manipulou-se a Confusão do Consumidor em duas de suas dimensões. Foi possível destacar a preponderância da estratégia por busca de informações e postergação da decisão, quando o consumidor se depara com situações confusas.

Why economics should be a modest and reasonable science

Unlike the methodological sciences such as mathematics and decision theory, which use the hypothetical-deductive method and may be fully expressed in complex mathematical models because their only truth criterion is logical consistency, the substantive sciences have as their truth criterion the correspondence to reality, adopt an empirical-deductive method, and are supposed to generalize from and often unreliable regularities and tendencies. Given this assumption, it is very difficult for economists to predict economic behavior, particularly major financial crises.

Racionalidade e pesquisa comportamental no direito: avanço científico ou retórica?

Esse é um trabalho sobre estudos comportamentais que questionam a confiabilidade empírica das premissas de racionalidade das ciências sociais. Décadas de pesquisa comportamental vêm nos ensinando é que a grande maioria das tendências cognitivas identificadas e comprovadas, que se afastam dos pressupostos da Teoria da Escolha Racional não são de forma alguma aleatórias, mas ao invés, são sistemáticas e previsíveis. A ideia unificando esse trabalho é de que a literatura de pesquisa comportamental pode nos permitir modelar e prever comportamentos relevantes para o direito, com pressupostos mais realistas sobre o comportamento humano. No entanto, alguns pesquisadores pintam uma figura entusiástica sobre o potencial que tal pesquisa possui para informar a análise jurídica e, assim, cometem algumas desatenções ao defender generalizações não embasadas por evidências científicas, quase aproximando-se do uso de uma mera retórica. Dado esse cenário, devemos procurar garantir que a incorporação das evidências da pesquisa comportamental no discurso jurídico seja acompanhada de maior ênfase na pesquisa empírica em ambientes específicos. Esse trabalho possui três objetivos. O primeiro é analisar as diferentes concepções de racionalidade e caso elas devem manter sua posição privilegiada nas ciências sociais. O segundo é tentar entender melhor a literatura de pesquisa comportamental que questionam a validade empírica dos axiomas da Teoria da Escolha Racional. O terceiro é identificar problemas na forma pela qual a pesquisa comportamental tem sido incorporada no discurso jurídico.

Análise e classificação de imagens de lesões da pele por atributos de cor, forma e textura utilizando máquina de vetor de suporte

The skin cancer is the most common of all cancers and the increase of its incidence must, in part, caused by the behavior of the people in relation to the exposition to the sun. In Brazil, the non-melanoma skin cancer is the most incident in the majority of the regions. The dermatoscopy and videodermatoscopy are the main types of examinations for the diagnosis of dermatological illnesses of the skin. The field that involves the use of computational tools to help or follow medical diagnosis in dermatological injuries is seen as very recent. Some methods had been proposed for automatic classification of pathology of the skin using images. The present work has the objective to present a new intelligent methodology for analysis and classification of skin cancer images, based on the techniques of digital processing of images for extraction of color characteristics, forms and texture, using Wavelet Packet Transform (WPT) and learning techniques called Support Vector Machine (SVM). The Wavelet Packet Transform is applied for extraction of texture characteristics in the images. The WPT consists of a set of base functions that represents the image in different bands of frequency, each one with distinct resolutions corresponding to each scale. Moreover, the characteristics of color of the injury are also computed that are dependants of a visual context, influenced for the existing colors in its surround, and the attributes of form through the Fourier describers. The Support Vector Machine is used for the classification task, which is based on the minimization principles of the structural risk, coming from the statistical learning theory. The SVM has the objective to construct optimum hyperplanes that represent the separation between classes. The generated hyperplane is determined by a subset of the classes, called support vectors. For the used database in this work, the results had revealed a good performance getting a global rightness of 92,73% for melanoma, and 86% for non-melanoma and benign injuries. The extracted describers and the SVM classifier became a method capable to recognize and to classify the analyzed skin injuries

Study of water and dimethylformamide interaction by computer simulation

Monte Carlo simulations of water-dimethylformamide (DMF) mixtures were performed in the isothermal and isobaric ensemble at 298.15 K and 1 atm. The intermolecular interaction energy was calculated using the classical 6-12 Lennard-Jones pairwise potential plus a Coulomb term. The TIP4P model was used for simulating water molecules, and a six-site model previously optimised by us was used to represent DMF. The potential energy for the water-DMF interaction was obtained via standard geometric combining rules using the original potential parameters for the pure liquids. The radial distribution functions calculated for water-DMF mixtures show well characterised hydrogen bonds between the oxygen site of DMF and hydrogen of water. A structureless correlation curve was observed for the interaction between the hydrogen site of the carbonyl group and the oxygen site of water. Hydration effects on the stabilisation of the DMF molecule in aqueous solution have been investigated using statistical perturbation theory. The results show that energetic changes involved in the hydration process are not strong enough to stabilise another configuration of DMF than the planar one.

Anderson localization and momentum-space entanglement

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Predicting epidemic outbreak from individual features of the spreaders

Knowing which individuals can be more efficient in spreading a pathogen throughout a determinate environment is a fundamental question in disease control. Indeed, over recent years the spread of epidemic diseases and its relationship with the topology of the involved system have been a recurrent topic in complex network theory, taking into account both network models and real-world data. In this paper we explore possible correlations between the heterogeneous spread of an epidemic disease governed by the susceptible-infected-recovered (SIR) model, and several attributes of the originating vertices, considering Erdos-Renyi (ER), Barabasi-Albert (BA) and random geometric graphs (RGG), as well as a real case study, the US air transportation network, which comprises the 500 busiest airports in the US along with inter-connections. Initially, the heterogeneity of the spreading is achieved by considering the RGG networks, in which we analytically derive an expression for the distribution of the spreading rates among the established contacts, by assuming that such rates decay exponentially with the distance that separates the individuals. Such a distribution is also considered for the ER and BA models, where we observe topological effects on the correlations. In the case of the airport network, the spreading rates are empirically defined, assumed to be directly proportional to the seat availability. Among both the theoretical and real networks considered, we observe a high correlation between the total epidemic prevalence and the degree, as well as the strength and the accessibility of the epidemic sources. For attributes such as the betweenness centrality and the k-shell index, however, the correlation depends on the topology considered.