Percolative phase transition on ferromagnetic insulator manganites: uncorrelated to correlated polaron clusters

In this work, we report an atomic scale study on the ferromagnetic insulator manganite LaMnO$_{3.12}$ using $\gamma-\gamma$ PAC spectroscopy. Data analysis reveals a nanoscopic transition from an undistorted to a Jahn-Teller-distorted local environment upon cooling. The percolation thresholds of the two local environments enclose a macroscopic structural transition (Rhombohedric-Orthorhombic). Two distinct regimes of JT-distortions were found: a high temperature regime where uncorrelated polaron clusters with severe distortions of the Mn$^{3+}$O$_{6}$ octahedra survive up to $T \approx 800 K$ and a low temperature regime where correlated regions have a weaker JT-distorted symmetry.Comment: 4 pages, 4 Figures, submitted to PRL, new version with more data, text reformulate

Clustering and preferential attachment in growing networks

We study empirically the time evolution of scientific collaboration networks in physics and biology. In these networks, two scientists are considered connected if they have coauthored one or more papers together. We show that the probability of scientists collaborating increases with the number of other collaborators they have in common, and that the probability of a particular scientist acquiring new collaborators increases with the number of his or her past collaborators. These results provide experimental evidence in favor of previously conjectured mechanisms for clustering and power-law degree distributions in networks.Comment: 13 pages, 2 figure

Stretched exponentials and power laws in granular avalanching

We introduce a model for granular avalanching which exhibits both stretched exponential and power law avalanching over its parameter range. Two modes of transport are incorporated, a rolling layer consisting of individual particles and the overdamped, sliding motion of particle clusters. The crossover in behaviour observed in experiments on piles of rice is attributed to a change in the dominant mode of transport. We predict that power law avalanching will be observed whenever surface flow is dominated by clustered motion. Comment: 8 pages, more concise and some points clarified

Hérnia Diafragmática Congénita. Casuística de 10 Anos

Os autores fizeram a revisão dos casos de hérnia diafragmática congénita admitidos na Unidade de Cuidados Intensivos Neonatais do Hospital de Dona Estefânia de Janeiro de 1984 a Dezembro de 1993 (10 anos). Neste período foram internados 53 recém-nascidos (RN) com hérnia diafragmática congénita tipo Bochdalek. A pesquisa incidiu sobre os índices de gravidade clínicos, radiológico, ventilatório, de oxigenação e mortalidade. Em 54,7% dos RN houve asfixia neonatal. A dificuldade respiratória teve início antes das 6 horas de vida em 43 dos RN (81.1%), mas o início dos sintomas foi imediato em 31. A hérnia localizava-se à esquerda em 77.4% dos casos. Em 5 casos não foi possível a correcção cirúrgia do defeito diafragmático. A mortalidade global foi 47.2%. Dos 48 RN operados faleceram 20 (41.7%). Em todas as crianças que faleceram, excepto numa, houve início imediato dos sintomas. A mortalidade dos RN com índice radiológico >6 foi de 81.5%. O índice ventilatório >1000 e o índice de oxigenação >40 tiveram valor preditivo de morte (mortalidade de 100% em ambos os casos). Nesta casuística, os achados que melhor se correlacionaram com o prognóstico foram: início imediato dos sintomas, I.R. >6, I.V.> 1000 e I.O.> 40

Network robustness and fragility: Percolation on random graphs

Recent work on the internet, social networks, and the power grid has addressed the resilience of these networks to either random or targeted deletion of network nodes. Such deletions include, for example, the failure of internet routers or power transmission lines. Percolation models on random graphs provide a simple representation of this process, but have typically been limited to graphs with Poisson degree distribution at their vertices. Such graphs are quite unlike real world networks, which often possess power-law or other highly skewed degree distributions. In this paper we study percolation on graphs with completely general degree distribution, giving exact solutions for a variety of cases, including site percolation, bond percolation, and models in which occupation probabilities depend on vertex degree. We discuss the application of our theory to the understanding of network resilience.Comment: 4 pages, 2 figure

On fermionic tilde conjugation rules and thermal bosonization. Hot and cold thermofields

A generalization of Ojima tilde conjugation rules is suggested, which reveals the coherent state properties of thermal vacuum state and is useful for the thermofield bosonization. The notion of hot and cold thermofields is introduced to distinguish different thermofield representations giving the correct normal form of thermofield solution for finite temperature Thirring model with correct renormalization and anticommutation properties.Comment: 13 page

EChOSim: The Exoplanet Characterisation Observatory software simulator

EChOSim is the end-to-end time-domain simulator of the Exoplanet Characterisation Observatory (EChO) space mission. EChOSim has been developed to assess the capability EChO has to detect and characterize the atmospheres of transiting exoplanets, and through this revolutionize the knowledge we have of the Milky Way and of our place in the Galaxy. Here we discuss the details of the EChOSim implementation and describe the models used to represent the instrument and to simulate the detection. Software simulators have assumed a central role in the design of new instrumentation and in assessing the level of systematics affecting the measurements of existing experiments. Thanks to its high modularity, EChOSim can simulate basic aspects of several existing and proposed spectrometers for exoplanet transits, including instruments on the Hubble Space Telescope and Spitzer, or ground-based and balloon borne experiments. A discussion of different uses of EChOSim is given, including examples of simulations performed to assess the EChO mission

Microsatellite markers isolated from Cabomba Aquatica S.l. (cabombaceae) from an enriched genomic library

Microsatellite primers were designed for the submersed aquatic plant Cabomba aquatica s.l. (Cabombaceae) and characterized to estimate genetic diversity parameters. Using a selective hybridization method, we designed and tested 30 simple sequence repeat loci using two natural populations of C. aquatica s.l., resulting in 13 amplifiable loci. Twelve loci were polymorphic, and alleles per locus ranged from two to four across the 49 C. aquatica s.l. individuals. Observed heterozygosity, expected heterozygosity, and fixation index varied from 0.0 to 1.0, 0.0 to 0.5, and -1.0 to -0.0667, respectively, for the Manaus population and from 0.0 to 1.0, 0.0 to 0.6, and -1.0 to 0.4643 for the Viruá population. The developed markers will be used in further taxonomic and population studies within Cabomba. This set of microsatellite primers represents the first report on rapid molecular markers in the genus.Microsatellite primers were designed for the submersed aquatic plant Cabomba aquatica s.l. (Cabombaceae) and characterized to estimate genetic diversity parameters. Using a selective hybridization method, we designed and tested 30 simple sequence repeat l31113CNQP - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORSEM INFORMAÇÃO457/2010The authors thank S. M. Costa for help during fieldwork, the staff of the Parque Nacional do Viruá and Instituto Nacional de Pesquisas da Amazônia (INPA) for field support, and A. P. Souza for technical support for the laboratory infrastructure. T.D.M.B.