Texto: Reducción a la teoría cuántica de Campos

La Teoría Cuántica de Campos constituye en la actualidad una teoría muy importante pues a través de ella se puede estudiar las propiedades e interacciones de las partículas fundamentales, por ejemplo, de electrones, positrones y fotones, es decir en el ámbito de la Electrodinámica Cuántica. En este contexto, la teoría cuántica de Campos es la base fundamental para el entendimiento de los fenómenos en la naturaleza. En este texto se toma en cuenta los conceptos, leyes y principios básicos de la teoría cuántica de Campos. Además, con la finalidad de tener una mejor comprensión del comportamiento de las partículas elementales, como electrones, positrones y fotones, se consideran las interacciones entre ellas, las cuales llevan a los diagramas de Feynman. Se ha elaborado un texto de naturaleza teórico-práctico, redactado en lenguaje simple. En cada capítulo se exponen de manera clara, directa y concisa las definiciones y formulaciones de los temas considerados.Trabado de investigacio

Non-adiabatic quantum effects from a Standard Model time-dependent Higgs vev

We consider the time-dependence of the Higgs vacuum expectation value (vev) given by the dynamics of the Standard Model and study the non-adiabatic production of both bosons and fermions, which is intrinsically non-perturbative. In the Hartree approximation, we analyse the general expressions that describe the dissipative dynamics due to the back-reaction of the produced particles. In particular, we solve numerically some relevant cases for the Standard Model phenomenology in the regime of relatively small oscillations of the Higgs vev.Comment: 35 pages, 15 figures and 2 table

Circulating microRNAs in sera correlate with soluble biomarkers of immune activation but do not predict mortality in ART treated individuals with HIV-1 infection: A case control study

Introduction: The use of anti-retroviral therapy (ART) has dramatically reduced HIV-1 associated morbidity and mortality. However, HIV-1 infected individuals have increased rates of morbidity and mortality compared to the non-HIV-1 infected population and this appears to be related to end-organ diseases collectively referred to as Serious Non-AIDS Events (SNAEs). Circulating miRNAs are reported as promising biomarkers for a number of human disease conditions including those that constitute SNAEs. Our study sought to investigate the potential of selected miRNAs in predicting mortality in HIV-1 infected ART treated individuals. Materials and Methods: A set of miRNAs was chosen based on published associations with human disease conditions that constitute SNAEs. This case: control study compared 126 cases (individuals who died whilst on therapy), and 247 matched controls (individuals who remained alive). Cases and controls were ART treated participants of two pivotal HIV-1 trials. The relative abundance of each miRNA in serum was measured, by RTqPCR. Associations with mortality (all-cause, cardiovascular and malignancy) were assessed by logistic regression analysis. Correlations between miRNAs and CD4+ T cell count, hs-CRP, IL-6 and D-dimer were also assessed. Results: None of the selected miRNAs was associated with all-cause, cardiovascular or malignancy mortality. The levels of three miRNAs (miRs -21, -122 and -200a) correlated with IL-6 while miR-21 also correlated with D-dimer. Additionally, the abundance of miRs -31, -150 and -223, correlated with baseline CD4+ T cell count while the same three miRNAs plus miR- 145 correlated with nadir CD4+ T cell count. Discussion: No associations with mortality were found with any circulating miRNA studied. These results cast doubt onto the effectiveness of circulating miRNA as early predictors of mortality or the major underlying diseases that contribute to mortality in participants treated for HIV-1 infection

Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study

Ristola M. on työryhmien DAD Study Grp ; Royal Free Hosp Clin Cohort ; INSIGHT Study Grp ; SMART Study Grp ; ESPRIT Study Grp jäsen.Background Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice. Methods and Findings A total of 17,954 HIV-positive individuals from the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study with >= 3 estimated glomerular filtration rate (eGFR) values after 1 January 2004 were included. Baseline was defined as the first eGFR > 60 ml/min/1.73 m2 after 1 January 2004; individuals with exposure to tenofovir, atazanavir, atazanavir/ritonavir, lopinavir/ritonavir, other boosted protease inhibitors before baseline were excluded. CKD was defined as confirmed (>3 mo apart) eGFR In the D:A:D study, 641 individuals developed CKD during 103,185 person-years of follow-up (PYFU; incidence 6.2/1,000 PYFU, 95% CI 5.7-6.7; median follow-up 6.1 y, range 0.3-9.1 y). Older age, intravenous drug use, hepatitis C coinfection, lower baseline eGFR, female gender, lower CD4 count nadir, hypertension, diabetes, and cardiovascular disease (CVD) predicted CKD. The adjusted incidence rate ratios of these nine categorical variables were scaled and summed to create the risk score. The median risk score at baseline was -2 (interquartile range -4 to 2). There was a 1: 393 chance of developing CKD in the next 5 y in the low risk group (risk score = 5, 505 events), respectively. Number needed to harm (NNTH) at 5 y when starting unboosted atazanavir or lopinavir/ritonavir among those with a low risk score was 1,702 (95% CI 1,166-3,367); NNTH was 202 (95% CI 159-278) and 21 (95% CI 19-23), respectively, for those with a medium and high risk score. NNTH was 739 (95% CI 506-1462), 88 (95% CI 69-121), and 9 (95% CI 8-10) for those with a low, medium, and high risk score, respectively, starting tenofovir, atazanavir/ritonavir, or another boosted protease inhibitor. The Royal Free Hospital Clinic Cohort included 2,548 individuals, of whom 94 individuals developed CKD (3.7%) during 18,376 PYFU (median follow-up 7.4 y, range 0.3-12.7 y). Of 2,013 individuals included from the SMART/ESPRIT control arms, 32 individuals developed CKD (1.6%) during 8,452 PYFU (median follow-up 4.1 y, range 0.6-8.1 y). External validation showed that the risk score predicted well in these cohorts. Limitations of this study included limited data on race and no information on proteinuria. Conclusions Both traditional and HIV-related risk factors were predictive of CKD. These factors were used to develop a risk score for CKD in HIV infection, externally validated, that has direct clinical relevance for patients and clinicians to weigh the benefits of certain antiretrovirals against the risk of CKD and to identify those at greatest risk of CKD.Peer reviewe

Introducción a la teoría cuántica de campos

En el presente texto se desarrolla la cubanización de los campos libres muy importante en el estudio de las interacciones de campos, los diagramas de Feynman. Asimismo, se estudia los procesos elementales en la Electrodinámica Cuántica y correcciones radiativas considerando diferentes métodos de regularización. La importancia del texto radica en el hecho de que constituye un instrumento que permite facilitar el proceso enseñanza-aprendizaje, de acuerdo con los Objetivos y contenidos de los programas oficiales, de la asignatura Teoría Cuántica de Campos I que se imparte en las carreras de ciencias. Asimismo; debido a su enfoque predominantemente método inductivo-deductivo a través del cual ha sido posible mostrar el desarrollo del formulismo que describen los conceptos descritos, así como también, el análisis de las demostraciones desarrolladas, prepara al estudiante para el estudio de la mecánica cuántica a nivel más avanzado.Trabado de investigacio

Estados ligados de campos clássicos interagentes em domínios finitos em dimensão (1 + 1 )

Orientador: Adolfo Maia JuniorTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb WataghinResumo: No presente trabalho, apresentamos primeiramente um breve resumo histórico sobre ondas solitárias (solitary waves) assim como definições do kink (Soliton) e estabilidade clássica. Também apresentamos o modelo de Dashen-Hasslacher-Neveu (DHN) [1], mostrando as contribuições para as correções radiativas da massa do kink. Começamos então com o cálculo da solução geral estática para o potencial V (f ) = -1/2M 2f 2 + l/4 f 4, determinando duas famílias de soluções as quais denominamos Soluções Elípticas tipo sn e cn. Mostramos que a condição de fronteira Vácuo - Vácuo não pode ser satisfeita por nenhuma das Soluções Elípticas tipo sn num domínio limitado. No entanto as Soluções Elípticas tipo cn podem satisfazer esta condição. Além disso, impondo condições de fronteira tipo Dirichlet mostramos a existência de uma única solução clássica para as Soluções Elípticas tipo sn dentro do domínio. Definimos então grandezas físicas, as quais denominamos respectivamente de "carga topológica", "energia total" (massa clássica) e "densidade de energia", em domínios finitos para as Soluções Elípticas tipo sn e cn. Em seguida, calculamos os níveis de energia dos estados ligados de um campo escalar c , o qual interage com outro campo escalar f num domínio finito (caixa) em dimensão (1 + 1). Estes cálculos são feitos para duas configurações clássicas do campo f : primeiramente, para um caso particular das Soluções Elípticas tipo sn, a saber, o kink, e depois consideramos um caso mais geral com o campo f dado pelas Soluções Elípticas tipo sn. No primeiro caso, mostra-se que quando a caixa é comprimida o nível de energia do estado fundamental do campo c se divide, o que pode ser interpretado como uma instabilidade levando à produção de pares partícula-antipartícula sob pequenas pertubações num regime semi-clássico. Para o segundo caso, mostramos que existem comprimentos críticos da caixa unidimensional em que os autovalores de energia tornam-se complexos levando a instabilidades para as soluções do campo cAbstract: In this work, we present firstly a brief historical summary of solitary waves, as well as definitions of the kink and classical stability. We present the model of Dashen-Hasslacher-Neveu (DHN) [1], showing the contributions for radiative corrections of the kink's mass. We start with the calculation of the general static solutions for the potential V (f ) = - 1/2 M2 f2 + l /4 f4 , by finding two families of solutions named Elliptic Solutions of type sn and cn. We show that the vacuum-vacuum boundary conditions can not be satisfied by any Elliptic sn-type Solution in afinite domain. On the other hand the Elliptic cn-type Solutions can satisfy this condition. We prove the uniqueness for Elliptic sn-type Solutions satisfying Dirichlet boundary conditions in a finite domain. Also we define expressions for the "topological charge", "total energy" (or classical mass) and "energy density" for Elliptic sn and cn-type Solutions in a finite domain. Next we calculate the energy levels of bound states of a scalar field c interacting with another scalar field f in a finite domain (box) in (1 +1) dimensions. We make these calculations for two classical configurations of the field f : Firstly a particular case of the Elliptic sn-type Solutions is considered, namely, the kink solution and later we consider as classical configuration of the field f , the Elliptic sn-type Solutions. For the first case, we show that when the box is squeezed the ground state level splits, which can be interpreted as an instability leading to a particle-antiparticle pair production under small perturbations in a semi-classical regime. For the second case, we show that there exist critical sizes of the box (one-dimensional) for which the energy eigenvalues become complex leading to instabilities for the solutions of the field cDoutoradoFísicaDoutor em Ciência

Métodos de regularização em teoria de campos e gama-fluidos

Orientador: Adolfo Maia JuniorDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica "Gleb Wataghin"Resumo: Na primeira parte, após um breve resumo da quantização de campos, estudamos o problema das integrais divergentes na Eletrodinâmica Quântica ( QED ) onde consideramos como exemplo a polarização do vácuo. Apresentamos três métodos de regularização: Cut-Off, Pauli- Villars e Regularização Dimensional. Na segunda parte, fazemos a dedução, com métodos da física estatística, do espectro de g -fluídos (O £ g £ 2 ;g ¹ 1), os quais são importantes para a cosmologia. Para 0 £ g < 1, obtemos unia divergência infravermelha, a qual é regularizada utilizando o método de Cut-Off adaptado para a região infravermelha. Como casos particulares obtemos o .espectro de Planck (g = 4/3 ) e do vácuo (g = 0). Estes resultados concordam com aqueles que são obtidos a partir dos princípios da termodinâmicaAbstract: In the first part, after a brief summary of the quantization of fields, we study the problem of the divergent integrals in the Quantum Electrodynamics (QED) where we consider as example the polarization of the vacuum. We present three methods of regularization: Cut-Off, Pauli- Villars and Dimensional Regularization. In the second part, we derive, using statistical physics methods, the spectrum of g -fluids (0 £ g £ 2; g ¹ 1), which are important in cosmology. For 0 £ g £ 1, we obtain an infrared divergence, which is regularized by the Cut-Off method adapted to an infrared region. As particular cases we obtain the Planck spectrum ( g = 4/3 ) and the spectrum of the vacuum ( g = 0). These results are in agreement with those obtained from thermodynamicsMestradoFísicaMestre em Físic