Dynamical quenching and annealing in self-organization multiagent models

We study the dynamics of a generalized Minority Game (GMG) and of the Bar Attendance Model (BAM) in which a number of agents self-organize to match an attendance that is fixed externally as a control parameter. We compare the usual dynamics used for the Minority Game with one for the BAM that makes a better use of the available information. We study the asymptotic states reached in both frameworks. We show that states that can be assimilated to either thermodynamic equilibrium or quenched configurations can appear in both models, but with different settings. We discuss the relevance of the parameter $G$ that measures the value of the prize for winning in units of the fine for losing. We also provide an annealing protocol by which the quenched configurations of the GMG can progressively be modified to reach an asymptotic equlibrium state that coincides with the one obtained with the BAM.Comment: around 20 pages, 10 figure

Semipurity of tempered Deligne cohomology

In this paper we define the formal and tempered Deligne cohomology groups, that are obtained by applying the Deligne complex functor to the complexes of formal differential forms and tempered currents respectively. We then prove the existence of a duality between them, a vanishing theorem for the former and a semipurity property for the latter. The motivation of these results comes from the study of covariant arithmetic Chow groups. The semi-purity property of tempered Deligne cohomology implies, in particular, that several definitions of covariant arithmetic Chow groups agree for projective arithmetic varieties

Thermal treatment of the minority game

We study a cost function for the aggregate behavior of all the agents involved in the Minority Game (MG) or the Bar Attendance Model (BAM). The cost function allows to define a deterministic, synchronous dynamics that yields results that have the main relevant features than those of the probabilistic, sequential dynamics used for the MG or the BAM. We define a temperature through a Langevin approach in terms of the fluctuations of the average attendance. We prove that the cost function is an extensive quantity that can play the role of an internal energy of the many agent system while the temperature so defined is an intensive parameter. We compare the results of the thermal perturbation to the deterministic dynamics and prove that they agree with those obtained with the MG or BAM in the limit of very low temperature.Comment: 9 pages in PRE format, 6 figure

Self-Segregation vs. Clustering in the Evolutionary Minority Game

Complex adaptive systems have been the subject of much recent attention. It is by now well-established that members (`agents') tend to self-segregate into opposing groups characterized by extreme behavior. However, while different social and biological systems manifest different payoffs, the study of such adaptive systems has mostly been restricted to simple situations in which the prize-to-fine ratio, $R$, equals unity. In this Letter we explore the dynamics of evolving populations with various different values of the ratio $R$, and demonstrate that extreme behavior is in fact {\it not} a generic feature of adaptive systems. In particular, we show that ``confusion'' and ``indecisiveness'' take over in times of depression, in which case cautious agents perform better than extreme ones.Comment: 4 pages, 4 figure

Mastectomia radical e unilateral no tratamento de mastite gangrenosa em cabras.

A sanidade da glândula mamária é essencial para a produção leiteira, sendo a mastite uma causa frequente de prejuízos para o produtor, além de sofrimento para o animal. O crescimento da pecuária caprina leiteira no nordeste brasileiro, é um importante recurso nutricional e fonte terapêutica a ser melhor aproveitada. Este fato tem despertado interesse de pesquisadores sob os mais diferentes aspectos. Diante disso, objetivou-se avaliar a mastectomia radical e unilateral como procedimentos cirúrgicos de escolha no tratamento da mastite gangrenosa. Foram utilizadas quatro cabras, na faixa etária de dois a três anos de idade, sem raça definida. Todos os animais passaram por exame clínico e foram considerados portadores de mastite gangrenosa de curso agudo variando de três a quatro dias pós-partos. Submetidas à anestesia epidural baixa e mastectomia radical e unilateral. O tempo de observação pós-operatória foi de 18 meses. Concluiu-se que a mastectomia, radical e unilateral proporciona o tratamento da mastite gangrenosa. É essencial a adoção de medidas práticas de baixo custo que facilitem a vida dos produtores diminuindo seus gastos. Têm-se a perspectiva de que este trabalho sirva de subsídio para a manutenção da fisiologia da mama e preservação dos animais no rebanho

Quantitative analysis of shadow X-ray Magnetic Circular Dichroism Photo-Emission Electron Microscopy

Shadow X-ray Magnetic Circular Dichroism Photo-Emission Electron Microscopy (XMCD-PEEM) is a recent technique, in which the photon intensity in the shadow of an object lying on a surface, may be used to gather information about the three-dimensional magnetization texture inside the object. Our purpose here is to lay the basis of a quantitative analysis of this technique. We first discuss the principle and implementation of a method to simulate the contrast expected from an arbitrary micromagnetic state. Text book examples and successful comparison with experiments are then given. Instrumental settings are finally discussed, having an impact on the contrast and spatial resolution : photon energy, microscope extraction voltage and plane of focus, microscope background level, electric-field related distortion of three-dimensional objects, Fresnel diffraction or photon scattering

New Superhard Phases for 3D C60-based Fullerites

We have explored new possible phases of 3D C60-based fullerites using semiempirical potentials and ab-initio density functional methods. We have found three closely related structures - two body centered orthorhombic and one body centered cubic - having 52, 56 and 60 tetracoordinated atoms per molecule. These 3D polymers result in semiconductors with bulk moduli near 300 GPa, and shear moduli around 240 GPa, which make them good candidates for new low density superhard materials.Comment: To be published in Physical Review Letter

Influence of growth stage on efficacy, absorption and translocation of glyphosate in Eragrostis plana.

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