A cognitive hierarchy model of behavior in the action commitment game

We apply the cognitive hierarchy model of Camerer et al. (Q J Econ 119(3):861-898, 2004)-where players have different levels of reasoning-to Huck et al. (Games Econ Behav 38:240-264, 2002) discrete version of Hamilton and Slutsky (Games Econ Behav 2:29-46, 1990) action commitment game-a duopoly with endogenous timing of entry. We show that, for an empirically reasonable average number of thinking steps, the model rules out Stackelberg equilibria, generates Cournot outcomes including delay, and outcomes where the first mover commits to a quantity higher than Cournot but lower than Stackelberg leader. We show that a cognitive hierarchy model with quantal responses can explain the most important features of the experimental data on the action commitment game in (2002). In order to gauge the success of the model in fitting the data, we compare it to a noisy Nash model. We find that the cognitive hierarchy model with quantal responses fits the data better than the noisy Nash model.

Aplicação de modelo matemático às propriedades reológicas de géis mistos de agarose e de goma guar

Certain biopolymers are capable of forming physically cross-linked gels in aqueous medium, stabilized by forces such as Coulombic, charge transfer, hydrogen bonding, dipole-dipole, van der Waals, and hydrophobic interactions. The mathematical description of these physical networks are difficult, but should contribute to a better understanding of the gelling process. The Clark and Ross-Murphy model was applied to experimental data for agarose-guar gum mixed systems, in which only agarose is the gelling polysaccharide. A computational routine based on the statistical maximum likehood principle was employed to estimate the f, K and a characteristic parameters. Statistical t-test and F-test were used to analyse the set of parameters.

Propriedades espectroscópicas Ab initio dos dímeros de van der waals Ne2 e Ar2

Results of high level ab initio calculations of the intermolecular potentials and theoretical dispersion coefficients for the Ne2 and Ar2 dimers were utilized to build analytical potentials for these species. The obtained potentials were used in the calculation of the dimers rovibrationals levels, and their respective spectroscopic constants determined. A comparison of high level experimental data with our theoretical results shows a very good agreement for Ne2, and also a good agreement for the Ar2 dimer.

Simulação da Química da Atmosfera Poluída por Automóveis Movidos a Álcool

Numerical modeling studies of urban atmospheres were performed with a photochemical box submodel which incorporates primary emission rates, temperature and solar irradiance rate coefficients. Actinic flux calculations were made for an appropriate latitude for Rio de Janeiro and initial concentrations and emission rates were taken from experimental data. The relative importance of individual reactions is discussed as well as the effect of enhanced aldehyde emissions from vehicles using ethanol and ethanol-containing fuel.

Modelagem dos processos químicos em plasmas de misturas gasosas usadas na corrosão de silício. Parte 1: CF4 / O2

The plasma etching of semiconductor surfaces with fluorine-containing compounds has technological interest. Presently, considerable effort is being devoted to understand the chemistry involved. In this work, a numerical modeling analysis of the gas-phase decomposition of CF4/O2 mixtures, in the presence of silicon, was performed. The relative importance of individual processes was determined as well as the effect of the parameters' uncertainties. The results were compared with experimental data. The main etching agent in the system is the fluorine atom. The concentration of the main species, SiF4, CO, CO2 and COF2 depend on the composition of the mixture.

Modelagem dos processos químicos em plasmas de misturas gasosas usadas na corrosão de silício. Parte 2: SF6 / O2

In this work, a numerical modeling analysis of the gas-phase decomposition of SF6 / O2 mixtures, in the presence of silicon, was performed. The relative importance of individual processes and the effect of the parameters' uncertainties were determined. The model was compared with experimental data for the plasma etching of silicon and with the calculated results for the CF4 / O2 system. In both systems the main etching agent is the fluorine atom and the concentration of the major species depends on the composition of the mixture. The etching rate is greater for SF6 / O2.

Análise das isotermas de adsorção de Cu(II), Cd(II), Ni(II) e Zn(II) pela N-(3,4-dihidroxibenzil) quitosana empregando o método da regressão não linear

Adsorption of Cu(II), Ni(II), Pb(II) and Zn(II) ions from aqueous solutions by N-(3,4-dihydroxybenzyl) chitosan have been carried out. The Langmuir (L), Freundlich (F), Langmuir - Freundlich (LF), Redlich-Peterson (RP) and Tóth (T) adsorption isotherms models have been applied to fit the experimental data. Nonlinear regression computational program "Enzefitte", which is a library of the more commonly used adsorption isotherm equations for obtaining tabular outuput suitable for plotting theoretical of fitted isotherms, has been used to estimate the adsorption parameters. These parameters were used to calculate the amount adsorbed q calc., a function of concentration (C).

Separação de espectros simulados e de luminescência total através do método generalizado de anulação do posto (GRAM)

A multivariate curve resolution method, "GENERALIZED RANK ANNIHILATION METHOD (GRAM)", is discussed and tested with simulated and experimental data. The analysis of simulated data provides general guidelines concerning the condition for uniqueness of a solution for a given problem. The second-order emission-excitation spectra of human and animal dental calculus deposits were used as an experimental data to estimate the performance of the above method. Three porphyrinic spectral profiles, for both human and cat, were obtained by the use of GRAM.

Modeling of Gold Cyanidation

The chemistry of gold dissolution in alkaline cyanide solution has continually received attention and new rate equations expressing the gold leaching are still developed. The effect of leaching parameters on gold gold cyanidation is studied in this work in order to optimize the leaching process. A gold leaching model, based on the well-known shrinking-core model, is presented in this work. It is proposed that the reaction takes place at the reacting particle surface which is continuously reduced as the reaction proceeds. The model parameters are estimated by comparing experimental data and simulations. The experimental data used in this work was obtained from Ling et al. (1996) and de Andrade Lima and Hodouin (2005). Two different rate equations, where the unreacted amount of gold is considered in one equation, are investigated. In this work, it is presented that the reaction at the surface is the rate controlling step since there is no internal diffusion limitation. The model considering the effect of non-reacting gold shows that the reaction orders are consistent with the experimental observations reported by Ling et al. (1996) and de Andrade Lima and Hodouin (2005). However, it should be noted that the model obtained in this work is based on assumptions of no side reactions, no solid-liquid mass transfer resistances and no effect from temperature.

Concepts and Reference. Defending a Dual Theory of Natural Kind Concepts

In this thesis I argue that the psychological study of concepts and categorisation, and the philosophical study of reference are deeply intertwined. I propose that semantic intuitions are a variety of categorisation judgements, determined by concepts, and that because of this, concepts determine reference. I defend a dual theory of natural kind concepts, according to which natural kind concepts have distinct semantic cores and non-semantic identification procedures. Drawing on psychological essentialism, I suggest that the cores consist of externalistic placeholder essence beliefs. The identification procedures, in turn, consist of prototypes, sets of exemplars, or possibly also theory-structured beliefs. I argue that the dual theory is motivated both by experimental data and theoretical considerations. The thesis consists of three interrelated articles. Article I examines philosophical causal and description theories of natural kind term reference, and argues that they involve, or need to involve, certain psychological elements. I propose a unified theory of natural kind term reference, built on the psychology of concepts. Article II presents two semantic adaptations of psychological essentialism, one of which is a strict externalistic Kripkean-Putnamian theory, while the other is a hybrid account, according to which natural kind terms are ambiguous between internalistic and externalistic senses. We present two experiments, the results of which support the strict externalistic theory. Article III examines Fodor’s influential atomistic theory of concepts, according to which no psychological capacities associated with concepts constitute them, or are necessary for reference. I argue, contra Fodor, that the psychological mechanisms are necessary for reference.

Termodinâmica estatística de líquidos com o método de Monte Carlo. II. O líquido clorofórmio

Thermodynamic properties and radial distribution functions for liquid chloroform were calculated using the Monte Carlo method implemented with Metropolis algorithm in the NpT ensemble at 298 K and 1 atm. A five site model was developed to represent the chloroform molecules. A force field composed by Lennard-Jones and Coulomb potential functions was used to calculate the intermolecular energy. The partial charges needed to represent the Coulombic interactions were obtained from quantum chemical ab initio calculations. The Lennard-Jones parameters were adjusted to reproduce experimental values for density and enthalpy of vaporization for pure liquid. All thermodynamic results are in excelent agreement with experimental data. The correlation functions calculated are in good accordance with theoretical results avaliable in the literature. The free energy for solvating one chloroform molecule into its own liquid at 298 K and 1 atm was computed as an additional test of the potential model. The result obtained compares well with the experimental value. The medium effects on cis/trans convertion of a hypotetical solute in water TIP4P and chloroform solvents were also accomplished. The results obtained from this investigation are in agreement with estimates of the continuous theory of solvation.

Avaliação da capacidade tamponante - um experimento participativo

The aim of this work is to show an experiment from which students can learn some of the main characteristics of buffer solutions. A mixture of some acid-base indicators, named as Yamada's indicator, can be used to estimate pH values in an acid-base titration of a buffer, with good approximation. In the experiment it is also possible to verify the relationship between the buffer capacity and the concentrations and the molar ratio of the components of a NH3 / NH4+ buffer solution. The shortage of experiments associated with the relative small importance given to many aspects of buffer solutions, is now explored with simplicity. In the proposed experiments, students prepare buffer solutions by themselves, calculate the pH, understand how acid-base indicators act and learn how buffer solutions work through graph constructed by sharing experimental data.

Statistical Analysis of an SEIR Epidemic Model

This thesis was focussed on statistical analysis methods and proposes the use of Bayesian inference to extract information contained in experimental data by estimating Ebola model parameters. The model is a system of differential equations expressing the behavior and dynamics of Ebola. Two sets of data (onset and death data) were both used to estimate parameters, which has not been done by previous researchers in (Chowell, 2004). To be able to use both data, a new version of the model has been built. Model parameters have been estimated and then used to calculate the basic reproduction number and to study the disease-free equilibrium. Estimates of the parameters were useful to determine how well the model fits the data and how good estimates were, in terms of the information they provided about the possible relationship between variables. The solution showed that Ebola model fits the observed onset data at 98.95% and the observed death data at 93.6%. Since Bayesian inference can not be performed analytically, the Markov chain Monte Carlo approach has been used to generate samples from the posterior distribution over parameters. Samples have been used to check the accuracy of the model and other characteristics of the target posteriors.

Utilização de modelos físico-químicos de adsorção no estudo do comportamento do cobre em solos argilosos

It was evaluated the applicability of Langmuir, Freundlich and Temkin models to copper adsorption in three classes of soils. Fractions of each soil were added to test tubes containing growing concentrations of the metal in solution. The tubes were shaken and the copper concentrations were determined in the extracts by atomic absorption spectrometry (AAS). The models offered a good fit for the experimental data indicating that presence of silicated clay had high influence on copper sorption. The Langmuir isotherm showed high influence of the organic matter in the absorption phenomenon. It was evidenced the importance of further studies related to Temkin model.

Estudo da adsorção de hidrogênio e sulfeto na superfície de paládio: aspectos experimentais (eletroquímica) e teóricos (ab initio e Teoria do Funcional da Densidade)

The adsorption of H and S2- species on Pd (100) has been studied with ab initio, density-functional calculations and electrochemical methods. A cluster of five Pd atoms with a frozen geometry described the surface. The computational calculations were performed through the GAUSSIAN94 program, and the basis functions adapted to a pseudo-potential obtained by using the Generator Coordinate Method adapted to the this program. Using the cyclic voltammetry technique through a Model 283 Potentiostat/Galvanostat E.G.&G-PAR obtained the electrochemical results. The calculated chemisorption geometry has a Pd-H distance of 1.55Å, and the potential energy surface was calculated using the Becke3P86//(GCM/DFT/SBK) methodology. The adsorption of S2- ions on Pd surface obtained both through comparison between the experimental and theoretical results, at MP2 level, suggest a S2- absorption into the metallic cluster. The produced Pd-(S2-) system was show to be very stable under the employed experimental conditions. The paper has shows the powerful aid of computational methods to interpret adsorption experimental data.