Higher spin symmetries and w∞ algebra in the conformal affine Toda model

As recently shown the conformal affine Toda models can be obtained via hamiltonian reduction from a two-loop Kac-Moody algebra. In this paper we propose a systematic procedure to analyze the higher spin symmetries of the conformal affine Toda models. The method is based on an explicit construction of infinite towers of extended conformal symmetry generators. Two fundamental building blocks of this construction are special spin-one and -two primary fields characterizing the conformal structure of these models. The connection to the algebra of area preserving diffeomorphisms on a two-manifold (w∞ algebra) is established.

Solitons, τ-functions and hamiltonian reduction for non-Abelian conformal affine Toda theories

We consider the Hamiltonian reduction of the two-loop Wess-Zumino-Novikov-Witten model (WZNW) based on an untwisted affine Kac-Moody algebra script Ĝ. The resulting reduced models, called Generalized Non-Abelian Conformal Affine Toda (G-CAT), are conformally invariant and a wide class of them possesses soliton solutions; these models constitute non-Abelian generalizations of the conformal affine Toda models. Their general solution is constructed by the Leznov-Saveliev method. Moreover, the dressing transformations leading to the solutions in the orbit of the vacuum are considered in detail, as well as the τ-functions, which are defined for any integrable highest weight representation of script Ĝ, irrespectively of its particular realization. When the conformal symmetry is spontaneously broken, the G-CAT model becomes a generalized affine Toda model, whose soliton solutions are constructed. Their masses are obtained exploring the spontaneous breakdown of the conformal symmetry, and their relation to the fundamental particle masses is discussed. We also introduce what we call the two-loop Virasoro algebra, describing extended symmetries of the two-loop WZNW models.

Hamiltonian reduction and the construction of q-deformed extensions of the Virasoro algebra

In this paper we employ the construction of the Dirac bracket for the remaining current of sl(2) q deformed Kac-Moody algebra when constraints similar to those connecting the sl(2)-Wess-Zumino-Witten model and the Liouville theory are imposed to show that it satisfies the q-Virasoro algebra proposed by Frenkel and Reshetikhin The crucial assumption considered in our calculation is the existence of a classical Poisson bracket algebra induced in a consistent manner by the correspondence principle, mapping the quantum generators into commuting objects of classical nature preserving their algebra.

Turning math attractive to computer science students: an application-to-model approach

This paper describes an innovative approach to develop the understanding about the relevance of mathematics to computer science. The mathematical subjects are introduced through an application-to-model scheme that lead computer science students to a better understanding of why they have to learn math and learn it effectively. Our approach consists of a single one semester course, taught at the first semester of the program, where the students are initially exposed to some typical computer applications. When they recognize the applications' complexity, the instructor gives the mathematical models supporting such applications, even before a formal introduction to the model in a math course. We applied this approach at Unesp (Brazil) and the results include a large reduction in the rate of students that abandon the college and better students in the final years of our program.

Renormalization of the ladder light-front Bethe-Salpeter equation in the Yukawa model

The reduction of the two-fermion Bethe-Salpeter equation in the framework of light-front dynamics is studied for the Yukawa model. It yields auxiliary three-dimensional quantities for the transition matrix and the bound state. The arising effective interaction can be perturbatively expanded in powers of the coupling constant gs allowing a defined number of boson exchanges; it is divergent and needs renormalization; it also includes the instantaneous term of the Dirac propagator. One possible solution of the renormalization problem of the boson exchanges is shown to be provided by expanding the effective interaction beyond single boson exchange. The effective interaction in ladder approximation up to order g4 s is discussed in detail. It is shown that the effective interaction naturally yields the box counterterm required to be introduced ad hoc previously. The covariant results of the Bethe-Salpeter equation can be recovered from the corresponding auxiliary three-dimensional quantities.

Intrauterine dentistry: an integrated model of prevention.

Intrauterine Dentistry is a highly relevant subject of our time. The use of preventive measures in the intrauterine stage can avoid several diseases, among these, dental caries. The WHO advises that from the 4th month of pregnancy, women should avoid the intake of sugar, so that the fetus, future child, does not develop an exaggerated attraction for these types of foods, thus being susceptible to caries. Through questionnaires sent to gynecologist-obstetricians and dentists, this research investigated the information they have about this subject and how they instruct their patients. Questionnaires were also sent to pregnant women requesting information about the instructions they had received for the prevention of oral diseases of their fetus. Seventy-one percent of the dentists and 80% of the gynecologist-obstetricians reported having instructed the pregnant women to reduce the intake of sugar. However, only 13.6% of the dentists and no gynecologist-obstetrician instructed the reduction of sugar intake between the 12th and 18th week of pregnancy. A total of 42.2% of the pregnant women referred to these instructions, but none received instruction as to the specific period of the 12th and 18th week. An ideal model of treatment for pregnant women must include integrated and multiprofessional treatment, in which general dentists and gynecologist-obstetricians work together with the participation of the patient.

The monosodium glutamate (MSG) obese rat as a model for the study of exercise in obesity

Obesity is an increasing problem in several countries, leading to health problems. Physical exercise, in turn, can be used effectively by itself or in combination with dietary restriction to trigger weight loss. The present study was designed to evaluate the effects of aerobic exercise training on lipid profile of obese male Wistar rats in order to verify if this model may be of value for the study of exercise in obesity. Obesity was induced by MSG administration (4mg/g, each other day, from birth to 14 days old) After 14 from drug administration, the rats were separated into two groups: MSG-S (sedentary) and MSG-T (exercise trained). Exercise training consisted in 1h/day, 5 days/week, with an overload of 5% bw, for 10 weeks. Rats of the same age and strain, receiving saline at birth, were used as control (C), and subdivided into two groups: C-S and C-T. At the end of the experimental period, MSG-T and C-T rats showed similar blood lactate and muscle glycogen responses to exercise training and acute exercise. MSG-S rats showed significantly higher carcass fat, serum triacylglycerol, serum insulin and liver total fat than C-S rats. On the other hand, MSG-T rats had lower carcass fat, serum triacylglycerol and liver total fat than MSG-S rats. There were no statistical differences in food intake and serum free fatty acids among the groups studied. These data indicate that this model may be of value for the study of exercise effects on tissue and circulating lipid profile in obesity.

Immune regulatory effect of pHSP65 DNA therapy in pulmonary tuberculosis: Activation of CD8+ cells, interferon-γ recovery and reduction of lung injury

A DNA vaccine based on the heat-shock protein 65 Mycobacterium leprae gene (pHSP65) presented a prophylactic and therapeutic effect in an experimental model of tuberculosis. In this paper, we addressed the question of which protective mechanisms are activated in Mycobacterium tuberculosis-infected mice after immune therapy with pHSP65. We evaluated activation of the cellular immune response in the lungs of infected mice 30 days after infection (initiation of immune therapy) and in those of uninfected mice. After 70 days (end of immune therapy), the immune responses of infected untreated mice, infected pHSP65-treated mice and infected pCDNA3-treated mice were also evaluated. Our results show that the most significant effect of pHSP65 was the stimulation of CD8+ lung cell activation, interferon-γ recovery and reduction of lung injury. There was also partial restoration of the production of tumour necrosis factor-α. Treatment with pcDNA3 vector also induced an immune stimulatory effect. However, only infected pHSP65-treated mice were able to produce significant levels of interferon-γ and to restrict the growth of bacilli.

Conceptual model for adaptable and extensible visual data exploration

Interactive visual representations complement traditional statistical and machine learning techniques for data analysis, allowing users to play a more active role in a knowledge discovery process and making the whole process more understandable. Though visual representations are applicable to several stages of the knowledge discovery process, a common use of visualization is in the initial stages to explore and organize a sometimes unknown and complex data set. In this context, the integrated and coordinated - that is, user actions should be capable of affecting multiple visualizations when desired - use of multiple graphical representations allows data to be observed from several perspectives and offers richer information than isolated representations. In this paper we propose an underlying model for an extensible and adaptable environment that allows independently developed visualization components to be gradually integrated into a user configured knowledge discovery application. Because a major requirement when using multiple visual techniques is the ability to link amongst them, so that user actions executed on a representation propagate to others if desired, the model also allows runtime configuration of coordinated user actions over different visual representations. We illustrate how this environment is being used to assist data exploration and organization in a climate classification problem.

Application of ARX neural networks to model the rate of penetration of petroleum wells drilling

Bit performance prediction has been a challenging problem for the petroleum industry. It is essential in cost reduction associated with well planning and drilling performance prediction, especially when rigs leasing rates tend to follow the projects-demand and barrel-price rises. A methodology to model and predict one of the drilling bit performance evaluator, the Rate of Penetration (ROP), is presented herein. As the parameters affecting the ROP are complex and their relationship not easily modeled, the application of a Neural Network is suggested. In the present work, a dynamic neural network, based on the Auto-Regressive with Extra Input Signals model, or ARX model, is used to approach the ROP modeling problem. The network was applied to a real oil offshore field data set, consisted of information from seven wells drilled with an equal-diameter bit.

Domain reduction using GRASP construction phase for transmission expansion planning problem

This paper proposes a new strategy to reduce the combinatorial search space of a mixed integer linear programming (MILP) problem. The construction phase of greedy randomized adaptive search procedure (GRASP-CP) is employed to reduce the domain of the integer variables of the transportation model of the transmission expansion planning (TM-TEP) problem. This problem is a MILP and very difficult to solve specially for large scale systems. The branch and bound (BB) algorithm is used to solve the problem in both full and the reduced search space. The proposed method might be useful to reduce the search space of those kinds of MILP problems that a fast heuristic algorithm is available for finding local optimal solutions. The obtained results using some real test systems show the efficiency of the proposed method. © 2012 Springer-Verlag.

Development of a low-Reynolds-number k-ω model for FENE-P fluids

A low-Reynolds-number k-ω model for Newtonian fluids has been developed to predict drag reduction of viscoelastic fluids described by the FENE-P model. The model is an extension to viscoelastic fluids of the model for Newtonian fluids developed by Bredberg et al. (Int J Heat Fluid Flow 23:731-743, 2002). The performance of the model was assessed using results from direct numerical simulations for fully developed turbulent channel flow of FENE-P fluids. It should only be used for drag reductions of up to 50 % (low and intermediate drag reductions), because of the limiting assumption of turbulence isotropy leading to an under-prediction of k, but compares favourably with results from k-ε models in the literature based on turbulence isotropy. © 2012 Springer Science+Business Media Dordrecht.

A mixed-integer LP model for the reconfiguration of radial electric distribution systems considering distributed generation

The problem of reconfiguration of distribution systems considering the presence of distributed generation is modeled as a mixed-integer linear programming (MILP) problem in this paper. The demands of the electric distribution system are modeled through linear approximations in terms of real and imaginary parts of the voltage, taking into account typical operating conditions of the electric distribution system. The use of an MILP formulation has the following benefits: (a) a robust mathematical model that is equivalent to the mixed-integer non-linear programming model; (b) an efficient computational behavior with exiting MILP solvers; and (c) guarantees convergence to optimality using classical optimization techniques. Results from one test system and two real systems show the excellent performance of the proposed methodology compared with conventional methods. © 2012 Published by Elsevier B.V. All rights reserved.

Doxorubicin induced dilated cardiomyopathy in a rabbit model: An update

Dilated cardiomyopathy (DCM) is characterized by chamber dilation and cardiac dysfunction. Because of the poor prognosis, models are needed for the investigation of and development of new therapeutic approaches, as well as stem cell therapy. Doxorubicin (DOX), used as chemotherapeutic agent, is reported to be cumulative cardiotoxic causing DCM. The aim of the study was to investigate the onset of systolic dysfunction using echocardiography in rabbits receiving two different doses of DOX (1. mg/kg twice a week and 2. mg/kg once a week). Twenty rabbits were treated with doxorubicin in two different doses for 6. weeks and compared with a control group treated with NaCl 0.9%. The effect of doxorubicin on the myocardium was investigated with histological analysis and scanning electron microscopy of left ventricle (LV), as well as in the interventricular septum (IVS) and right ventricle (RV). The results showed a high mortality rate for rabbits receiving 2. mg/kg once a week. A significant reduction in systolic function was present in animals treated with DOX after 6. weeks, with decreased ejection fraction and shortening fraction. Histology and electron microscopy revealed vacuolization, intracytoplasmic granulation, necrosis and interstitial fibrosis in LV, as well as in the IVS and RV. Doxorubicin induced changes are present in the LV, RV and IVS, and the administration at the dose of 1. mg/kg twice a week for only 6. weeks is safe and sufficient to induce DCM in rabbits. © 2012 Elsevier Ltd.

Curcumin-mediated photodynamic inactivation of Candida albicans in a murine model of oral candidiasis

In vitro investigations of curcumin-mediated photodynamic therapy (PDT) are encouraging, but there is a lack of reliable in vivo evidence of its efficacy. This study describes the photoinactivation of Candida albicans in a murine model of oral candidiasis, using curcumin as a photosensitizer. Forty immunosuppressed mice were orally inoculated with C. albicans and after five days, they received topical curcumin (20, 40 and 80 μM) and illumination with LED light. The use of curcumin or light alone were also investigated. Positive control animals did not receive any treatment and negative control animals were not inoculated with C. albicans. The number of surviving yeast cells was determined and analyzed by ANOVA and Tukey's post-hoc test (α = 0.05). Histological evaluation of the presence of yeast and inflammatory reaction was also conducted. All exposures to curcumin with LED light caused a significant reduction in C. albicans viability after PDT, but the use of 80 μM curcumin associated with light was able to induce the highest log10 reduction in colony counts (4 logs). It was concluded that curcumin-mediated PDT proved to be effective for in vivo inactivation of C. albicans without harming the host tissue of mice. © 2013 ISHAM.