On ""Schwinger mechanism for gluon pair production in the presence of arbitrary time dependent chromo-electric field""

Recently the paper ""Schwinger mechanism for gluon pair production in the presence of arbitrary time dependent chromo-electric field"" by G. C. Nayak was published [Eur. Phys. J. C 59: 715, 2009; arXiv:0708.2430]. Its aim is to obtain an exact expression for the probability of non-perturbative gluon pair production per unit time per unit volume and per unit transverse momentum in an arbitrary time-dependent chromo-electric background field. We believe that the obtained expression is open to question. We demonstrate its inconsistency on some well-known examples. We think that this is a consequence of using the socalled ""shift theorem""[arXiv:hep-th/0609192] in deriving the expression for the probability. We make some critical comments on the theorem and its applicability to the problem in question.

Scalar form factors and nuclear interactions

The scalar-isoscalar term in the two-pion exchange NN potential is abnormally large and does not respect the hierarchy of effects predicted by chiral perturbation theory. We argue that this anomaly is associated with non-perturbative effects, which are also present in the pi N scalar form factor.

Linear covariant gauges on the lattice

Linear covariant gauges, such as Feynman gauge, are very useful in perturbative calculations. Their non-perturbative formulation is, however, highly non-trivial. In particular, it is a challenge to define linear covariant gauges on a lattice. We consider a class of gauges in lattice gauge theory that coincides with the perturbative definition of linear covariant gauges in the formal continuum limit. The corresponding gauge-fixing procedure is described and analyzed in detail, with an application to the pure SU(2) case. In addition, results for the gluon propagator in the two-dimensional case are given. (C) 2008 Elsevier B.V. All rights reserved.

User perspectives on the Swedish Maternal Health Care Register

Background: Established in 1999, the Swedish Maternal Health Care Register (MHCR) collects data on pregnancy, birth, and the postpartum period for most pregnant women in Sweden. Antenatal care (ANC) midwives manually enter data into the Web-application that is designed for MHCR. The aim of this study was to investigate midwives? experiences, opinions and use of the MHCR. Method: A national, cross-sectional, questionnaire survey, addressing all Swedish midwives working in ANC, was conducted January to March 2012. The questionnaire included demographic data, preformed statements with six response options ranging from zero to five (0 = totally disagree and 5 = totally agree), and opportunities to add information or further clarification in the form of free text comments. Parametric and non-parametric methods and logistic regression analyses were applied, and content analysis was used for free text comments. Results: The estimated response rate was 53.1%. Most participants were positive towards the Web-application and the included variables in the MHCR. Midwives exclusively engaged in patient-related work tasks perceived the register as burdensome (70.3%) and 44.2% questioned the benefit of the register. The corresponding figures for midwives also engaged in administrative supervision were 37.8% and 18.5%, respectively. Direct electronic transfer of data from the medical records to the MHCR was emphasised as significant future improvement. In addition, the midwives suggested that new variables of interest should be included in the MHCR ? e.g., infertility, outcomes of previous pregnancy and birth, and complications of the index pregnancy. Conclusions: In general, the MHCR was valued positively, although perceived as burdensome. Direct electronic transfer of data from the medical records to the MHCR is a prioritized issue to facilitate the working situation for midwives. Finally, the data suggest that the MHCR is an underused source for operational planning and quality assessment in local ANC centres.

Sistema de aquisição do ciclo pressão-volume cardíaco por métodos não-invasivos

A aquisição do ciclo pressão-volume é de grande importância para diagnóstico de cardiopatias e principalmente para o acompanhamento de intervenções terapêuticas, porém os métodos hoje utilizados são caros e agressivos ao paciente, reduzindo por estes motivos sua aplicação. Este estudo pretende obter, por métodos não-invasivos, o ciclo pressão-volume do ventrículo esquerdo de pacientes humanos. Isto consiste na aquisição dos sinais P(t) e V(t) simultaneamente e a apresentação de um gráfico P(V). Para tanto, após a revisão bibliográfica, decidiu-se utilizar a ecocardiografia com detecção automática de bordos, para obtenção do volume ventricular e a medição da onda de pressão transmitida através da artéria braquial para um manguito inflado com ar, conectado a um transdutor piezo-resistivo em ponte. A aquisição da pressão pelo método não-invasivo é comparada a dados resultantes da aquisição invasiva da pressão arterial por catéter intra-aórtico que é considerado padrãoouro. Os sinais são condicionados e digitalizados em uma placa de aquisição com conversor A/D de 8 bits e micro controlador 80c196. Os dados digitalizados são então enviados serialmente para um computador onde são gerados os gráficos. Obteve-se de cinco pacientes nove aquisições simultâneas da pressão invasiva através de catéter intra-aórtico e do protótipo desenvolvido resultando concordância segundo o método de Bland e Altman (1986) (r=0,989; d + 2s= 6,52; d - 2s =-6,07), comprovando a eficiência do método de aquisição. Obteve-se resultado satisfatório também quanto à operação sistema desenvolvido pois foram realizadas dez aquisições em cinco pacientes, registrando-se gráficos bastante similares aos apresentados na literatura disponível.

Essays on regulation and risk

In this thesis, we investigate some aspects of the interplay between economic regulation and the risk of the regulated firm. In the first chapter, the main goal is to understand the implications a mainstream regulatory model (Laffont and Tirole, 1993) have on the systematic risk of the firm. We generalize the model in order to incorporate aggregate risk, and find that the optimal regulatory contract must be severely constrained in order to reproduce real-world systematic risk levels. We also consider the optimal profit-sharing mechanism, with an endogenous sharing rate, to explore the relationship between contract power and beta. We find results compatible with the available evidence that high-powered regimes impose more risk to the firm. In the second chapter, a joint work with Daniel Lima from the University of California, San Diego (UCSD), we start from the observation that regulated firms are subject to some regulatory practices that potentially affect the symmetry of the distribution of their future profits. If these practices are anticipated by investors in the stock market, the pattern of asymmetry in the empirical distribution of stock returns may differ among regulated and non-regulated companies. We review some recently proposed asymmetry measures that are robust to the empirical regularities of return data and use them to investigate whether there are meaningful differences in the distribution of asymmetry between these two groups of companies. In the third and last chapter, three different approaches to the capital asset pricing model of Kraus and Litzenberger (1976) are tested with recent Brazilian data and estimated using the generalized method of moments (GMM) as a unifying procedure. We find that ex-post stock returns generally exhibit statistically significant coskewness with the market portfolio, and hence are sensitive to squared market returns. However, while the theoretical ground for the preference for skewness is well established and fairly intuitive, we did not find supporting evidence that investors require a premium for supporting this risk factor in Brazil.

Um estudo sobre a concepção de paradoxo segundo o pensamento de Augustus de Morgan

This work aims to analyze the concept of "paradox" posed in the work of The Budget Paradox (1872) of mathematical and logical English Augustus De Morgan (1806-1871). Here it is important to note that a large part of this book consists of re-prints of a series of writings by the author in journal Athenaeum, where its performance as auditor of literature. The tests refer to some scientific work produced between the years 1489 and 1866 and the rules of selection for the composition of the work is, basically, the methodological aspects used in the completion or disclosed by such scholars. The concept of paradox is presented in two distinct moments. At first, we found a study of definitions for the term in a philosophical approach, characterizing it as something that requires further investigation; which was complemented with the classic examples of a scientific context. In the second, we present a concept advocated by De Morgan and, under this perspective, that he conceptualized the "paradox" is directly related to the non-usual methods employed in the formulation of new scientific theories. In this study some of these scientific concepts are detailed, where, through the redemption history, engaging in issues of our study Mathematics, Physics, of Logic, among others. Possession of the preliminary analysis and comparison with the design of De Morgan, it became possible to diagnose some limitations in the conceptualization suggested by the author. Further, evidenced, in front of the cases, the nonlinearity of the process of production of knowledge and hence the progress of science

Ergonomia e Odontologia: determinantes da postura corporal dos estudantes da clínica-escola de uma Universidade Federal

Posture is one of the most worrying problems dentists face. That is because of the high incidence of low back pathologies regarding the professional activity, despite the development on the field of Dental Ergonomics. This work took place at the dental schoolclinic at a Federal University, and it was grounded on the Ergonomic Principles in the workplace. Its main objective was to analyze the determinants of inadequate posture adopted by students inasmuch as the adoption of non ergonomic methods at the school-clinic may influence them to develop inadequate postures in their working environment. The analysis of the activity showed us that it requires some complex procedures in the patient s mouth. Thus, when the students carry out the activity, they start to adopt, although unconsciously, inadequate postures which will make easier the visual accuracy and the access to the operation focus. In case there is no internal (body awareness) or external warning mechanisms (the professor s or the partner s counseling) regarding posture or possible risks which lead them to self-correction, the students become vulnerable to osteomuscle disorders. The time pressure, because the students are expected to perform their task in a predetermined clinical time. The facts related to each patient s variability as well as the stress caused by the expectations to get their work done in time make the students to advance it believing they will waste time if they help their partners or using an indirect view. We could also notice that there was no assistant to perform the job of minor ones, as well as there was no professor who could actually connect the knowledge on Ergonomics to its working practice. The conclusions of this work stand out the need of widen the discussion at the academic environment regarding health professionals in places such as universities. The ergonomic principles in the workplace aim a multidisciplinary analysis based on the experience of students, professors, staff members and janitors that can contribute to some reflection upon the issue and consequently actions which will bring positive changes at the working environment

Information Visualization to Enhance Sensitivity and Selectivity in Biosensing

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

Thermal analysis as a screening technique for the characterization of babassu flour and its solid fractions after acid and enzymatic hydrolysis

The babassu (Orbignya phalerata) is a native tree found in northern Brazil. Extracts of the babassu coconut have been widely used in industry. Babassu flour has about 60% starch, thus, besides nourishment it can be used as an alternative biofuel source. However, the properties of this starch lack of study and understanding. The main purpose of this study was to investigate the thermal behavior of raw babassu flour and its solid hydrolyzed fraction. The analyses were carried out using SHIMADZU DSC and TG thermic analyzers. The results demonstrated a reduction in thermal stability of the solid hydrolyzed fraction compared to raw matter. The kinetic parameters were investigated using non-isothermal methods and the parameters obtained for its decomposition process were an E(a) of 166.86 kJ mol(-1) and a frequency factor (beta) of 6.283 x 1014 min(-1); this was determined to be a first order reaction (n = 1). (C) 2011 Elsevier B.V. All rights reserved.

Freezing of the QCD coupling constant and the pion form factor

The possibility that the QCD coupling constant (alpha(s)) has an infrared finite behavior (freezing) has been extensively studied in recent years. We compare phenomenological values of the frozen QCD running coupling between different classes of solutions obtained through non-perturbative Schwinger-Dyson Equations. With these solutions were computed QCD predictions for the asymptotic pion form factor which, in turn, were compared with experiment.

Vacuum polarization effects in hyperon-rich dense matter - a nonperturbative treatment

We derive the equation of state (EOS) for electrically charged neutral dense matter using the quantum hadrodynamics (QHD) model. This is carried out in a non-perturbative manner including quantum corrections for baryons through a realignment of vacuum with baryon-antibaryon condensates. This yields the results of relativistic Hartree approximation of summing over baryonic tadpole diagrams. The quantum corrections from the scalar meson is also taken into account in a similar way. This leads to a softening of the EOS for the hyperonic matter. The formalism also allows Lis to make a self-consistent calculation of the in-medium sigma meson mass. The effects of such quantum corrections on the composition of charged neutral dense matter is considered. The effect of the resulting EOS on the structure of neutron stars is also studied.

Coulomb gauge quark model, vacuum condensates and high density quark matter

We consider here a Coulomb gauge quark model which includes an explicit construct for a nontrivial vacuum structure in QCD at finite density. Non-perturbative renormalization of ultraviolet diverges is performed by adding counterterms. The equation of state for u and d quark matter at zero temperature is calculated in the Hartree-Fock approximation.

On dynamical gluon mass generation

The effective gluon propagator constructed with the pinch technique is governed by a Schwinger-Dyson equation with special structure and gauge properties, that can be deduced from the correspondence with the background field method. Most importantly the non-perturbative gluon self-energy is transverse order-by-order in the dressed loop expansion, and separately for gluonic and ghost contributions, a property which allows for a meanigfull truncation. A linearized version of the truncated Schwinger-Dyson equation is derived, using a vertex that satisfies the required Ward identity and contains massless poles. The resulting integral equation, subject to a properly regularized constraint, is solved numerically, and the main features of the solutions are briefly discussed.

Concerning the Landau pole in 3-3-1 models

Some 3 - 3 - 1 models predict the existence of a non-perturbative regime at the TeV scale. We study in these models and their supersymmetric extensions, the energy at which the non-perturbative limit and a Landau-like pole arise. An order of magnitude for the mass of the extra neutral vector boson, Z', present in these models is also obtained.