Critical behavior of a non-equilibrium interacting particle system driven by an oscillatory field

First- and second-order temperature driven transitions are studied, in a lattice gas driven by an oscillatory field. The short time dynamics study provides upper and lower bounds for the first-order transition points obtained using standard simulations. The difference between upper and lower bounds is a measure for the strength of the first-order transition and becomes negligible small for densities close to one half. In addition, we give strong evidence on the existence of multicritical points and a critical temperature gap, the latter induced by the anisotropy introduced by the driving field.Comment: 12 pages, 4 figures; to appear in Europhys. Let

Rôle des canaux ionique dans la mort cellulaire induit par stress osmotique

The work presented in the present thesis relates to the role of ion channels in response to (ionic and non-ionic) hyperosmotic stresses and their interactions with signaling events leading to PCD in plant. Early cell responses such as cytosolic calcium increase and ROS production classically involved in PCD process, seems not to be involved in hyperosmotic-induced cell death in BY2 tobacco and A. thaliana cultured cells. When BY2 tobacco cells were subjected to hyperosmotic stress, an early influx of sodium through non-selective cation channels participates in the development of PCD through mitochondrial dysfunction and NADPH-oxidase-dependent O2•– generation. On the contrary, non-ionic hyperosmotic stress resulted in an early decrease in anion currents. To further investigate the role of anion channels in non-ionic hyperosmotic stress further experiments were conducted by using A.thaliana cells of the anion channel mutant SLAC1. Results showed that the delayed activation of SLAC1 channels was involved in the non-ionic hyperosmotic stress induced pathway leading to cell death. Interestingly, the early anion channel activity decrease could participate to signalisation or osmotic adjustment allowing cell adaptation and survival, when a second set of events, namely superoxide anion (O2•-) generation by NADPH-oxidase and anion channel activation could participate in PCD development of a part of the cell population. In addition, the potential role of small peptides belonging to the FMRFamide-like peptide (FLP) family described in metazoan in osmoregulation in A. thaliana was investigated. By using synthetic peptides, based on FLPs homolog genes existing in A. thaliana, it was possible to demonstrate that these putative FLPs are involved in hyperosmotic stress response. Overall, the present work shed light on the importance and the complexity of ion channels regulation in the signaling pathways and the processes leading to PCDLe travaux présenté dans cette thèse concerne le rôle des canaux ioniques de la membrane plasmique en réponse à des stress salins et non salins ainsi qu’aux interactions possibles avec d’autres événements de signalisation conduisant à la mort cellulaire programmée (PCD). Nous avons montré que les réponses cellulaires précoces: tels que l`augmentation du calcium cytosolique et la production de ROS, classiquement impliqués lors de la PCD, ne semblaient pas être impliqué dans la mort cellulaire induite par les stress hyperosmotiques chez les cellules en culture de tabacco BY2 ou d’A. thaliana. Nous avons montré que, dans les cas de stress salin chez les cellules de BY2 un influx précoce de sodium à travers des canaux cationiques non spécifiques participe au développement de la PCD en entraînant un disfonctionement mitochondrial et la production de O2• - par des NADPH oxydases. Dans le cas de stress hyperosmotique non-ionique, nous avons observé une diminaution précoce de l’intensité des courants anioniques. Afin de poursuivre l’étude du rôle des canaux anioniques lors du stress hyperosmotique non salin, nous avons utilisé des cellules A.thaliana nous permettant de travailler avec le mutant de canal anionique SLAC1. Nous avons constaté que l’activation retardée des canaux SLAC1 participait au développement de la PCD induite par un stress hyperosmotique non salin. La réduction précoce de l'activité des canaux anioniques pourrait participer à la signalisation ou l'ajustement osmotique permettant l'adaptation et la survie cellulaire alors que des évènements retardés, à savoir la production d'anion superoxyde (O2• -) par les NADPH-oxydases et l'activation des canaux anioniques pourraient participer au développement de la PCD d'une partie de la population cellulaire. Nous avons aussi étudié le rôle potentiel des petits peptides appartenant à la famille des peptides FMRFamide décrite chez les métazoaires à l'osmorégulation chez des cellules d’A. thaliana. Des génes susceptibles de coder de tels peptides sont en effet présent dans le génome d’A. thaliana. En utilisant des peptides synthétiques, nous avons montré que ces FLPS putatifs pourraient participer aux réponses induites losr de stress hyperosmotique chez les plantes. Ce travail illustre la complexité et l'importance de la régulation des canaux ioniques dans les voies de signalisation et les processus conduisant à la PC

Revisiting the nonequilibrium phase transition of the triplet-creation model

The nonequilibrium phase transition in the triplet-creation model is investigated using critical spreading and the conservative diffusive contact process. The results support the claim that at high enough diffusion the phase transition becomes discontinuous. As the diffusion probability increases the critical exponents change continuously from the ordinary directed percolation (DP) class to the compact directed percolation (CDP). The fractal dimension of the critical cluster, however, switches abruptly between those two universality classes. Strong crossover effects in both methods make it difficult, if not impossible, to establish the exact location of the tricritical point.Comment: 7 pages, 12 figure

Permutation complexity of interacting dynamical systems

The coupling complexity index is an information measure introduced within the framework of ordinal symbolic dynamics. This index is used to characterize the complexity of the relationship between dynamical system components. In this work, we clarify the meaning of the coupling complexity by discussing in detail some cases leading to extreme values, and present examples using synthetic data to describe its properties. We also generalize the coupling complexity index to the multivariate case and derive a number of important properties by exploiting the structure of the symmetric group. The applicability of this index to the multivariate case is demonstrated with a real-world data example. Finally, we define the coupling complexity rate of random and deterministic time series. Some formal results about the multivariate coupling complexity index have been collected in an Appendix.Comment: 16 pages, 6 figure

Main difficulties, challenges and advantages identified in residential real estate development partnerships: case studies

A realização de parcerias é uma ação estratégica adotada por empresas que visam obter o máximo das oportunidades em mercados em que, isoladamente, não seriam capazes de atuar em padrões competitivos.\ud Tal estratégia possibilita agregar conhecimento e tecnologia, “aprender rapidamente sobre mercados não\ud conhecidos” (DOZ; HAMEL, 2000) e ampliar inserção de mercado e/ou espectro de atuação. Em suma,\ud possibilita realizar o que uma empresa não seria capaz de realizar sozinha [com as mesmas características\ud e/ou prazos, qualidade e resultados]” (DOZ; HAMEL, 2000). No setor do Real Estate um volume significativo de parcerias foi realizado por empresas que, capitalizadas em decorrência da abertura de capital, ou ainda em função da intensificação das atividades do setor, se depararam com a necessidade de ampliar a abrangência geográfica de atuação e/ou diversificar a segmentação de produtos, para alcançar as metas de crescimento planejadas. Frente aos objetivos traçados, foram realizadas alianças estratégicas, cujas empresas parceiras apresentavam principalmente duas características: atuação regional fora dos limites de abrangência das atividades da empresa em expansão e atuação em segmentos de mercado distintos de seu “core business”. Este artigo visa realizar uma análise comparativa entre parcerias realizadas por duas empresas atuantes predominantemente na cidade de São Paulo, sendo uma delas uma empresa incorporadora e a outra uma empresa gerenciadora de investimentos, que capta e investe recursos financeiros no mercado imobiliário, atuando na gestão dos investimentos e dos empreendimentos objeto dos recursos investidos. Tal análise\ud baseou-se no estudo de caso das referidas parcerias, sendo ambas firmadas com empresas atuantes no\ud Nordeste brasileiro, objetivando a Empresa Principal–EP1, o espalhamento geográfico. Esta análise \ud comparativa visa reconhecer as principais dificuldades, desafios e vantagens identificadas em cada parceria, sob o ponto de vista das “Empresas Principais”. As informações foram coletadas por meio da aplicação de um questionário às “Empresas Principais” e, a partir da compilação dos dados, foi elaborada uma análise diagnóstica comparativa visando apresentar um conjunto de dados organizados sistematicamente, que possam oferecer subsídios aos profissionais do setor para reflexões acerca de aspectos que podem ser reutilizados e questões que devem ser revisadas, para melhoria contínua de desempenho em parcerias futuras. O presente artigo integra uma pesquisa mais abrangente, não limitada aos estudos de caso aqui\ud apresentados, a qual embasará a dissertação de mestrado a ser apresentada no programa de Pós-Graduação de Engenharia Civil da Escola Politécnica da USP. Palavras chave: Parceria, estratégia, diversificação geográfica, Real Estate Residencial, capital aberto.Establishing partnerships is a strategy adopted by companies which aim to obtain maximum gains in markets where they wouldn‟t be able to be competitive if working isolated. This strategy allows putting together knowledge and technology, “enabling fast learning about unknown markets” (DOZ; HAMEL, 2000 – self-translation) and broadening market or acting area insertion. In short, it allows accomplishing something a single company would not be able to do on its own [maintaining the characteristics and / or schedules, quality and results]” (DOZ; HAMEL, 2000 – self-translation). In Real Estate, a significant number of partnerships have been developed by companies which, capitalized as the result of their IPOs or because of intense activity in the segment, faced the need to broaden their geographical reach and/or diversify products in order to reach established growth goals. In this scenario of a determined set of objectives, strategic alliances were established\ud and the companies involved in these partnerships usually presented two main characteristics: regional focus that reached beyond the expanding company‟s market; and target markets that were different from the ir core business. This article presents a comparative analysis of partnerships established by two companies predominantly\ud acting in São Paulo‟s market: A Real Estate Development Company and a company which manages Financial Resources in Real Estate, acting in the management of investments and also managing the real estate developments in which the funds were allocated. The analysis was based on the study of these partnerships, both of them established with companies working on the Northeast area in Brazil, with the Main Company-MC2\ud aiming at geographical diversity. This comparison is focused on recognizing the main difficulties, challenges and advantages identified in each partnership under the perspective of the “Main Company”. All the information was gathered by means of a questionnaire answered by the “Main Companies”. Based on the compilation of data, a comparative diagnosis was elaborated in order to obtain an organized database which could be the basis for Real Estate professionals to reflect upon aspects that could be reapplied and matters that should be revised in order to achieve a continuous improvement in future partnerships. The present article is part of a broader research, not limited to the case studies included in this paper. The complete study will be the foundation of a thesis to be presented to the Civil Engineering department at University of São Paulo. Key words: Partnership, strategy, geographical diversity, Residential Real Estate, IPO

Praxis der Datenerfassung mit Drohnen für GIS und Vermessung

In der Vorbereitung zur Bauphase von Projekten ist die Visualisierung sowie die Erfassung tagesaktueller Naturstandsdaten ein gewichtiger Aspekt. Bilder von Online-Karten, die via Satellit oder Flugzeug erstellt wurden, können bis zu mehreren Jahren alt sein. Drohnen mit Kameras bestückt können Gebiete gezielt befliegen und nach anschließender Auswertung werden die Daten zur Vermessung und Visualisierung herangezogen. Mit Hilfe der drohnengestützten Photogrammmetrie werden so digitale Karten, Geländemodelle, 3D Modelle rasch und tagesaktuell generiert. Ein wesentlicher Faktor stellt die weitere Integration der Daten in Verwaltungssysteme dar. Die generierten Pläne können in einer Verwaltungssoftware und/oder einer GIS Software direkt verarbeitet werden. Der administrative Aufwand, bei der Verortung von Sachdaten, wird dabei nicht nur durch die Visualisierung erheblich verringert. Beispielsweise soll hier die Digitalisierung von Friedhöfen genannt werden, die durch diese Technologie kostengünstig und rasch realisiert werden kann. Die durch Drohnenbefliegung generierten 3D Volumenmodelle von Steinbrüchen sind nicht nur für Visualisierungen interessant, sondern die daraus gewonnenen Höhenschichtmodelle, digitalen Gelände- oder Oberflächenmodelle dienen auch Vermessungen und sind Behördenkonform. Die Befliegung mit Flugrobotern, mit anschließender photogrammetrischer Auswertung, bietet mit Orthofotos, 3D Modellen und Luftbildern meist eine kostengünstig Alternative gegenüber der terrestrischen Vermessung. Das verwendete uLFZ (unbemannte Luftfahrzeug) muss von der Flugsicherungsbehörde (ACG = Austro Control) für den Betrieb zugelassenen werden, sowie der Pilot die entsprechende Befähigung nachweisen

Creep en estado fisurado en hormigones reforzados con fibras

El fib Model Code 2010 presenta avances significativos para uso de Hormigón Reforzado con Fibras ya que no sólo considera su clasificación en función de los niveles resistentes sino que brinda criterios para el diseño estructural de elementos como losas armadas, losas sin armadura convencional, uniones de columnas, paredes y muros. Sin embargo el documento no considera casos donde las cargas sostenidas den lugar a deformaciones diferidas (fluencia). Esto genera un interés particular para las macrofibras poliméricas y se ha formado un comité de la RILEM “Creep behavior on cracked sections in FRC”. Este trabajo analiza los mecanismos que provocan deformaciones diferidas en hormigones con fibras en estado fisurado y discute en qué casos tales deformaciones adquieren relevancia. Se sintetizan resultados sobre hormigones con fibras de acero y poliméricas

Appropriateness of correlated first order auto-regressive processes for modeling daily temperature records

The present study investigates linear and volatile (nonlinear) correlations of first-order autoregressive process with uncorrelated AR (1) and long-range correlated CAR (1) Gaussian innovations as a function of the process parameter ($\theta$). In the light of recent findings \cite{jano}, we discuss the choice of CAR (1) in modeling daily temperature records. We demonstrate that while CAR (1) is able to capture linear correlations it is unable to capture nonlinear (volatile) correlations in daily temperature records.Comment: Accepted for publication in Physica

Long term persistence in the sea surface temperature fluctuations

We study the temporal correlations in the sea surface temperature (SST) fluctuations around the seasonal mean values in the Atlantic and Pacific oceans. We apply a method that systematically overcome possible trends in the data. We find that the SST persistence, characterized by the correlation $C(s)$ of temperature fluctuations separated by a time period $s$, displays two different regimes. In the short-time regime which extends up to roughly 10 months, the temperature fluctuations display a nonstationary behavior for both oceans, while in the asymptotic regime it becomes stationary. The long term correlations decay as $C(s) \sim s^{-\gamma}$ with $\gamma \sim 0.4$ for both oceans which is different from $\gamma \sim 0.7$ found for atmospheric land temperature.Comment: 14 pages, 5 fiure