Upgrades of Genetic Programming for Data-Driven Modeling of Time Series.

In many engineering fields and scientific disciplines, the results of experiments are in the form of time series, which can be quite problematic to interpret and model. Genetic programming tools are quite powerful in extracting knowledge from data. In this work, several upgrades and refinements are proposed and tested to improve the explorative capabilities of symbolic regression (SR) via genetic programming (GP) for the investigation of time series, with the objective of extracting mathematical models directly from the available signals. The main task is not simply prediction but consists of identifying interpretable equations, reflecting the nature of the mechanisms generating the signals. The implemented improvements involve almost all aspects of GP, from the knowledge representation and the genetic operators to the fitness function. The unique capabilities of genetic programming, to accommodate prior information and knowledge, are also leveraged effectively. The proposed upgrades cover the most important applications of empirical modeling of time series, ranging from the identification of autoregressive systems and partial differential equations to the search of models in terms of dimensionless quantities and appropriate physical units. Particularly delicate systems to identify, such as those showing hysteretic behavior or governed by delayed differential equations, are also addressed. The potential of the developed tools is substantiated with both a battery of systematic numerical tests with synthetic signals and with applications to experimental data.

Data driven theory for knowledge discovery in the exact sciences with applications to thermonuclear fusion.

In recent years, the techniques of the exact sciences have been applied to the analysis of increasingly complex and non-linear systems. The related uncertainties and the large amounts of data available have progressively shown the limits of the traditional hypothesis driven methods, based on first principle theories. Therefore, a new approach of data driven theory formulation has been developed. It is based on the manipulation of symbols with genetic computing and it is meant to complement traditional procedures, by exploring large datasets to find the most suitable mathematical models to interpret them. The paper reports on the vast amounts of numerical tests that have shown the potential of the new techniques to provide very useful insights in various studies, ranging from the formulation of scaling laws to the original identification of the most appropriate dimensionless variables to investigate a given system. The application to some of the most complex experiments in physics, in particular thermonuclear plasmas, has proved the capability of the methodology to address real problems, even highly nonlinear and practically important ones such as catastrophic instabilities. The proposed tools are therefore being increasingly used in various fields of science and they constitute a very good set of techniques to bridge the gap between experiments, traditional data analysis and theory formulation.

A comprehensive study of the uncertainties in bolometric tomography on JET using the maximum likelihood method.

Essential physical quantities of magnetically confined plasmas are derived on a routine basis from bolometric reconstructions. In the last few years at the Joint European Torus (JET), the Maximum Likelihood method has demonstrated the capability of providing reliable reconstructions for this class of ill-posed problems. The article is focused on quantifying the effects of important sources of errors, usually underestimated, that can influence both the reconstructions and the derived quantities. A complete set of phantoms has been used to test the robustness of the technique. The main sources of uncertainties investigated in this contribution are random noise, presence of outliers in the measurements, uncertainty of the position of the magnetic topology, and missing measurements from damaged or unreliable bolometers. The study provides a comprehensive quantification of the uncertainties to associate with most typical emissivities encountered in practice and constitutes a good basis for a more accurate evaluation of the power balances on the JET.

Improved equilibrium reconstructions by advanced statistical weighting of the internal magnetic measurements.

In a Tokamak the configuration of the magnetic fields remains the key element to improve performance and to maximise the scientific exploitation of the device. On the other hand, the quality of the reconstructed fields depends crucially on the measurements available. Traditionally in the least square minimisation phase of the algorithms, used to obtain the magnetic field topology, all the diagnostics are given the same weights, a part from a corrective factor taking into account the error bars. This assumption unduly penalises complex diagnostics, such as polarimetry, which have a limited number of highly significant measurements. A completely new method to choose the weights, to be given to the internal measurements of the magnetic fields for improved equilibrium reconstructions, is presented in this paper. The approach is based on various statistical indicators applied to the residuals, the difference between the actual measurements and their estimates from the reconstructed equilibrium. The potential of the method is exemplified using the measurements of the Faraday rotation derived from JET polarimeter. The results indicate quite clearly that the weights have to be determined carefully, since the inappropriate choice can have significant repercussions on the quality of the magnetic reconstruction both in the edge and in the core. These results confirm the limitations of the assumption that all the diagnostics have to be given the same weight, irrespective of the number of measurements they provide and the region of the plasma they probe.

Influence of plasma diagnostics and constraints on the quality of equilibrium reconstructions on Joint European Torus.

One of the main approaches to thermonuclear fusion relies on confining high temperature plasmas with properly shaped magnetic fields. The determination of the magnetic topology is, therefore, essential for controlling the experiments and for achieving the required performance. In Tokamaks, the reconstruction of the fields is typically formulated as a free boundary equilibrium problem, described by the Grad-Shafranov equation in toroidal geometry and axisymmetric configurations. Unfortunately, this results in mathematically very ill posed problems and, therefore, the quality of the equilibrium reconstructions depends sensitively on the measurements used as inputs and on the imposed constraints. In this paper, it is shown how the different diagnostics (Magnetics Measurements, Polarimetry and Motional Stark Effect), together with the edge current density and plasma pressure constraints, can have a significant impact on the quality of the equilibrium on JET. Results show that both the Polarimetry and Motional Stark Effect internal diagnostics are crucial in order to obtain reasonable safety factor profiles. The impact of the edge current density constraint is significant when the plasma is in the H-mode of confinement. In this plasma scenario the strike point positions and the plasma last closed flux surface can change even by centimetres, depending on the edge constraints, with a significant impact on the remapping of the equilibrium-dependent diagnostics and of pedestal physics studies. On the other hand and quite counter intuitively, the pressure constraint can severely affect the quality of the magnetic reconstructions in the core. These trends have been verified with several JET discharges and consistent results have been found. An interpretation of these results, as interplay between degrees of freedom and available measurements, is provided. The systematic analysis described in the paper emphasizes the importance of having sufficient diagnostic inputs and of properly validating the results of the codes with independent measurements.

A importância do saneamento básico na aplicação dos princípios de cidades saudáveis: o caso de Balneário Camboriú - estudo de caso

Este artigo é fruto de análises de um estudo de caso efetuado em Balneário Camboriú no qual foram levantadas as condições do saneamento básico da cidade balneária e turística, comparando-se com as políticas de cidades saudáveis. (AU)

[The experience of public service users with group psychotherapy: a qualitative study]. / A experiência de usuários do serviço público em psicoterapia de grupo: estudo qualitativo.

OBJECTIVE: To assess the experience of public service users in a time-limited psychotherapeutic group dynamic intervention. METHODS: Eleven patients were randomly selected from a group of 52 who had participated in an efficacy study and were interviewed in-depth. Their account was submitted to content analysis, according to the Grounded Theory methodology. RESULTS: In general, patients accepted well and positively evaluated the psychotherapy intervention. The main findings were the importance of patient's interaction with the group participants, and their therapeutic course after the intervention, when most of them carried on with psychotherapy. CONCLUSIONS: The psychotherapeutic intervention was well accepted among the patients, had a favorable outcome and stimulated them to proceed with psychotherapy.

Development of a biosensor for monitoring of glycerol during alcoholic fermentation.

A biosensor for the measurement of glycerol in FIA was constructed using covalently immobilized glycerokinase and glycerol-3-phosphate oxidase in conjunction with a Pt based hydrogen peroxide probe. Different immobilization strategies have been studied including random and asymmetric immobilization onto a polymeric support and immobilization onto two different membranes. The latter resulted in the best configuration for batch measurement. The most effective configuration for measurement in FIA was the immobilization of glycerokinase in a glass beads reactor coupled with glycerol-3-phosphate oxidase on a preactivated Immobilon AV membrane kept at the electrode surface. Using a 250-microliter injection loop, 3 mmol ATP(Mg+2) in 0.1 M borate buffer pH 8.5 and a flow rate of 0.5 ml/min, a linear response in the 2 x 10(-6)/10(-3) mol/l range and a detection limit of 5 x 10(-7) mol/l were obtained for glycerol. Lifetime of the glycerol-3-phosphate membrane was extended up to 1 month by storage in the working buffer containing 1% DEAE-dextran and 5% lactitol. More than 350 samples can be assayed with this system. The biosensor was used to monitor off-line glycerol production during alcoholic fermentations carried out at different pHs and temperatures.

Case study: sexual abuse of boys by females.

Two examples of boys who experienced unwanted sexual contact with females are presented. The literature regarding this type of abuse is reviewed and supports the finding that such contact is relatively common and may have definite negative consequences for the victim. Conventional interview techniques can frequently fail to uncover these occurrences. Clinical, psychological, and sociocultural factors contribute to difficult eliciting the data. Even when young males attempt to report unwanted sexual contact, caregivers may fail to respond in a manner indicating sensitivity to the trauma. Further research could help to determine the long-term consequences of such experiences in male children and adolescents.

[The use of Mersilene mesh in the treatment of giant laparoceles]. / L'impiego della rete di Mersilene nel trattamento dei grandi laparoceli.

The paper reports on experience with the use of Mersilene mesh in 6 patients with giant laparoceles. Besides being physiologically compatible, Mersilene mesh is recommended when traditional techniques fail. The Rives technique was used, placing the prostheses between the posterior sheath and the rectus muscle; in one case it was inserted under the peritoneum. A good local and general preparation for the operation is recommended. Even though the introduction of prosthetic materials into the body is not always non-injurious, the use of Mersilene mesh is advised because of its easy positioning and the low incidence of complications.