Teoria quântica do campo escalar real com autoacoplamento quártico - simulações de Monte Carlo na rede com um algoritmo worm

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O despojamento em São Bernardo de Claraval e São Francisco de Assis (séculos XII e XIII)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Voz narrativa e memória: a busca de identidade pelas protagonistas de Felicidade clandestina, de Clarice Lispector e de Lives of girls and women, de Alice Munro. -

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

A construção de espaço e cultura: trajetórias migratórias entre Monte Azul (MG) e Rio Claro (SP)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Contaminação por nitrato no Aquífero Adamantina: o caso do município de Monte Azul Paulista - SP

Pós-graduação em Geociências e Meio Ambiente - IGCE

Study of the underlying event at forward rapidity in pp collisions at root s=0.9, 2.76, and 7 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estimativa da erosão na microbacia do Córrego do Gambá no município de Monte Alto, SP

Pós-graduação em Agronomia (Ciência do Solo) - FCAV

Using the Ferrenberg-Swendsen Monte Carlo method for nonuniversal exponents

We use the method of Monte Carlo evolution in the coupling constant space of Ferrenberg and Swendsen to evaluate the nonuniversal exponent η* associated to a linear defect in a 2d Ising model. © 1989.

Emprego do método eletromagnético (em) na investigação e mapeamento de contaminações geradas por cemitérios: o caso de Monte Alto/SP

The use of geophysical methods in the analysis and mapping of likely contamination plumes has shown a huge value in the development of researches related to environmental issues. Among the main geophysical methods applied to this purpose, the geoelectrical methods stand out, being based on the use of electric and electromagnetic fields. The electromagnetic method (EM) uses physical environment responses created by electromagnetic field propagation, consisting of an alternated electric output and a magnetization force, used to obtain the electric conductivity (σ) of the subsurface materials. It has a broad application in the mineral exploration and prospection, and its use has been also efficient in environmental researches. By the electromagnetic method, this work examined and mapped possible contaminations created by cemetery leachate in the Saudade's Cemetery, located in the city of Monte Alto, Sao Paulo, where sedimentary rocks of the Bauru Group are exposed. Cemetery leachate is a putrefactive liquid, generated from the decomposition of organic matter, which contains substances that can contaminate soil and groundwater. Results achieved in this work show that the use of the electromagnetic method is an important indirect tool in the investigation of environmental contaminations in areas with highly contrasting physical properties

Description of Rhodnius montenegrensis n. sp (Hemiptera: Reduviidae: Triatominae) from the state of Rondonia, Brazil

We present here a multisource approach that takes advantage of several disciplines to address a taxonomic issue. A triatomine related to Rhodnius robustus Larrousse, 1927 was recently found in the state of Rondonia, Brazil. The name Rhodnius montenegrensis n. sp. is suggested because it was found in the municipality of Monte Negro. The main differences between these two species can be detected in the female and male genitalia, but there are also noticeable differences in their eggs. Molecular analysis using PCR-RFLP technique and Bayesian inferences based on a fragment of the Cytochrome b (Cyt b) gene corroborated the morphological findings. We used this integrative approach to address the taxonomic decision for a new Rhodnius species and its relationship with others of this genus. Results obtained herein stress that morphology must be used as the major approach for obtaining phenotypic information, and molecular data should be taken as a complementary tool.

Survey of hearing disorders in an urban population in Rondonia, Northern Brazil

OBJECTIVE: To identify the prevalence of hearing loss for the population in the urban area. METHODS: A cross-sectional household survey based on the World Health Organization Ear and Hearing Disorders Survey Protocol was conducted in 298 households in the urban area of Monte Negro, Rondonia, Northern Brazil, from 2005 to 2007. Ear examinations, behavioral audiometry and pure tone audiometry were conducted on 577 individuals. RESULTS: The results showed that 3.8% (95%CI 2.17;5.45) of population were classifi ed in the disabling hearing impairment category. The prevalence of moderate hearing impairment was 3.4%; severe impairment was 0.4%; and profound hearing impairment was not found. CONCLUSIONS: The impairing hearing loss prevalence found in this study is within of the international prevalence for this level of hearing loss and smaller than observed in a previous study in the South region of Brazil.

A molecular dynamics study of the influence of chain branching on the properties of polymer systems

Die vorliegende Arbeit beschäftigt sich mit dem Einfluß von Kettenverzweigungen unterschiedlicher Topologien auf die statischen Eigenschaften von Polymeren. Diese Untersuchungen werden mit Hilfe von Monte-Carlo- und Molekular-Dynamik-Simulationen durchgeführt.Zunächst werden einige theoretische Konzepte und Modelle eingeführt, welche die Beschreibung von Polymerketten auf mesoskopischen Längenskalen gestatten. Es werden wichtige Bestimmungsgrößen eingeführt und erläutert, welche zur quantitativen Charakterisierung von Verzweigungsstrukturen bei Polymeren geeignet sind. Es wird ebenso auf die verwendeten Optimierungstechniken eingegangen, die bei der Implementierung des Computerprogrammes Verwendung fanden. Untersucht werden neben linearen Polymerketten unterschiedliche Topolgien -Sternpolymere mit variabler Armzahl, Übergang von Sternpolymeren zu linearen Polymeren, Ketten mit variabler Zahl von Seitenketten, reguläre Dendrimere und hyperverzweigte Strukturen - in Abhängigkeit von der Lösungsmittelqualität. Es wird zunächst eine gründliche Analyse des verwendeten Simulationsmodells an sehr langen linearen Einzelketten vorgenommen. Die Skalierungseigenschaften der linearen Ketten werden untersucht in dem gesamten Lösungsmittelbereich vom guten Lösungsmittel bis hin zu weitgehend kollabierten Ketten im schlechten Lösungsmittel. Ein wichtiges Ergebnis dieser Arbeit ist die Bestätigung der Korrekturen zum Skalenverhalten des hydrodynamischen Radius Rh. Dieses Ergebnis war möglich aufgrund der großen gewählten Kettenlängen und der hohen Qualität der erhaltenen Daten in dieser Arbeit, insbesondere bei den linearen ketten, und es steht im Widerspruch zu vielen bisherigen Simulations-Studien und experimentellen Arbeiten. Diese Korrekturen zum Skalenverhalten wurden nicht nur für die linearen Ketten, sondern auch für Sternpolymere mit unterchiedlicher Armzahl gezeigt. Für lineare Ketten wird der Einfluß von Polydispersität untersucht.Es wird gezeigt, daß eine eindeutige Abbildung von Längenskalen zwischen Simulationsmodell und Experiment nicht möglich ist, da die zu diesem Zweck verwendete dimensionslose Größe eine zu schwache Abhängigkeit von der Polymerisation der Ketten besitzt. Ein Vergleich von Simulationsdaten mit industriellem Low-Density-Polyäthylen(LDPE) zeigt, daß LDPE in Form von stark verzweigten Ketten vorliegt.Für reguläre Dendrimere konnte ein hochgradiges Zurückfalten der Arme in die innere Kernregion nachgewiesen werden.

Confocal microscopy applied to the study of single entity fluorescence and light scattering

A sample scanning confocal optical microscope (SCOM) was designed and constructed in order to perform local measurements of fluorescence, light scattering and Raman scattering. This instrument allows to measure time resolved fluorescence, Raman scattering and light scattering from the same diffraction limited spot. Fluorescence from single molecules and light scattering from metallic nanoparticles can be studied. First, the electric field distribution in the focus of the SCOM was modelled. This enables the design of illumination modes for different purposes, such as the determination of the three-dimensional orientation of single chromophores. Second, a method for the calculation of the de-excitation rates of a chromophore was presented. This permits to compare different detection schemes and experimental geometries in order to optimize the collection of fluorescence photons. Both methods were combined to calculate the SCOM fluorescence signal of a chromophore in a general layered system. The fluorescence excitation and emission of single molecules through a thin gold film was investigated experimentally and modelled. It was demonstrated that, due to the mediation of surface plasmons, single molecule fluorescence near a thin gold film can be excited and detected with an epi-illumination scheme through the film. Single molecule fluorescence as close as 15nm to the gold film was studied in this manner. The fluorescence dynamics (fluorescence blinking and excited state lifetime) of single molecules was studied in the presence and in the absence of a nearby gold film in order to investigate the influence of the metal on the electronic transition rates. The trace-histogram and the autocorrelation methods for the analysis of single molecule fluorescence blinking were presented and compared via the analysis of Monte-Carlo simulated data. The nearby gold influences the total decay rate in agreement to theory. The gold presence produced no influence on the ISC rate from the excited state to the triplet but increased by a factor of 2 the transition rate from the triplet to the singlet ground state. The photoluminescence blinking of Zn0.42Cd0.58Se QDs on glass and ITO substrates was investigated experimentally as a function of the excitation power (P) and modelled via Monte-Carlo simulations. At low P, it was observed that the probability of a certain on- or off-time follows a negative power-law with exponent near to 1.6. As P increased, the on-time fraction reduced on both substrates whereas the off-times did not change. A weak residual memory effect between consecutive on-times and consecutive off-times was observed but not between an on-time and the adjacent off-time. All of this suggests the presence of two independent mechanisms governing the lifetimes of the on- and off-states. The simulated data showed Poisson-distributed off- and on-intensities, demonstrating that the observed non-Poissonian on-intensity distribution of the QDs is not a product of the underlying power-law probability and that the blinking of QDs occurs between a non-emitting off-state and a distribution of emitting on-states with different intensities. All the experimentally observed photo-induced effects could be accounted for by introducing a characteristic lifetime tPI of the on-state in the simulations. The QDs on glass presented a tPI proportional to P-1 suggesting the presence of a one-photon process. Light scattering images and spectra of colloidal and C-shaped gold nano-particles were acquired. The minimum size of a metallic scatterer detectable with the SCOM lies around 20 nm.

Atomic force microscopy of biomimetic systems

This thesis was driven by the ambition to create suitable model systems that mimic complex processes in nature, like intramolecular transitions, such as unfolding and refolding of proteins, or intermolecular interactions between different cell compo-nents. Novel biophysical approaches were adopted by employing atomic force mi-croscopy (AFM) as the main measurement technique due to its broad diversity. Thus, high-resolution imaging, adhesion measurements, and single-molecule force distance experiments were performed on the verge of the instrumental capabilities. As first objective, the interaction between plasma membrane and cytoskeleton, me-diated by the linker protein ezrin, was pursued. Therefore, the adsorption process and the lateral organization of ezrin on PIP2 containing solid-supported membranes were characterized and quantified as a fundament for the establishment of a biomimetic model system. As second component of the model system, actin filaments were coated on functionalized colloidal probes attached on cantilevers, serving as sensor elements. The zealous endeavor of creating this complex biomimetic system was rewarded by successful investigation of the activation process of ezrin. As a result, it can be stated that ezrin is activated by solely binding to PIP2 without any further stimulating agents. Additional cofactors may stabilize and prolong the active conformation but are not essentially required for triggering ezrin’s transformation into an active conformation. In the second project, single-molecule force distance experiments were performed on bis-loop tetra-urea calix[4]arene-catenanes with different loading rates (increase in force per second). These macromolecules were specifically designed to investigate the rupture and rejoining mechanism of hydrogen bonds under external load. The entangled loops of capsule-like molecules locked the unbound state of intramolecular hydrogen bonds mechanically, rendering a rebinding observable on the experimental time scale. In conjunction with Molecular Dynamics simulations, a three-well potential of the bond rupture process was established and all kinetically relevant parameters of the experiments were determined by means of Monte Carlo simulations and stochastic modeling. In summary, it can be stated that atomic force microscopy is an invaluable tool to scrutinize relevant processes in nature, such as investigating activation mechanisms in proteins, as shown by analysis of the interaction between F-actin and ezrin, as well as exploring fundamental properties of single hydrogen bonds that are of paramount interest for the complete understanding of complex supramolecular structures.

Local Earthquake Tomography by trans-dimensional Monte Carlo Sampling

In this study a new, fully non-linear, approach to Local Earthquake Tomography is presented. Local Earthquakes Tomography (LET) is a non-linear inversion problem that allows the joint determination of earthquakes parameters and velocity structure from arrival times of waves generated by local sources. Since the early developments of seismic tomography several inversion methods have been developed to solve this problem in a linearized way. In the framework of Monte Carlo sampling, we developed a new code based on the Reversible Jump Markov Chain Monte Carlo sampling method (Rj-McMc). It is a trans-dimensional approach in which the number of unknowns, and thus the model parameterization, is treated as one of the unknowns. I show that our new code allows overcoming major limitations of linearized tomography, opening a new perspective in seismic imaging. Synthetic tests demonstrate that our algorithm is able to produce a robust and reliable tomography without the need to make subjective a-priori assumptions about starting models and parameterization. Moreover it provides a more accurate estimate of uncertainties about the model parameters. Therefore, it is very suitable for investigating the velocity structure in regions that lack of accurate a-priori information. Synthetic tests also reveal that the lack of any regularization constraints allows extracting more information from the observed data and that the velocity structure can be detected also in regions where the density of rays is low and standard linearized codes fails. I also present high-resolution Vp and Vp/Vs models in two widespread investigated regions: the Parkfield segment of the San Andreas Fault (California, USA) and the area around the Alto Tiberina fault (Umbria-Marche, Italy). In both the cases, the models obtained with our code show a substantial improvement in the data fit, if compared with the models obtained from the same data set with the linearized inversion codes.