Logarithmic growth dynamics in software networks

In a recent paper, Krapivsky and Redner (Phys. Rev. E, 71 (2005) 036118) proposed a new growing network model with new nodes being attached to a randomly selected node, as well to all ancestors of the target node. The model leads to a sparse graph with an average degree growing logarithmically with the system size. Here we present compeling evidence for software networks being the result of a similar class of growing dynamics. The predicted pattern of network growth, as well as the stationary in- and out-degree distributions are consistent with the model. Our results confirm the view of large-scale software topology being generated through duplication-rewiring mechanisms. Implications of these findings are outlined.Comment: 7 pages, 3 figures, published in Europhysics Letters (2005

Pion Production in Neutrino-Nucleon Reactions

We construct a model for the weak pion production off the nucleon, which in addition to the weak excitation of the $\Delta(1232)$ resonance and its subsequent decay into $N\pi$, it includes also some background terms required by chiral symmetry. We re-fit the $C_5^A(q^2)$ form factor to the flux averaged $\nu_\mu p \to \mu^-p\pi^+$ ANL $q^2-$differential cross section data, finding a substantially smaller contribution of the $\Delta$ pole mechanism than traditionally assumed in the literature. We also show that the interference between the Delta pole and the background terms produces parity-violating contributions to the pion angular differential cross section.Comment: To appear in the proceedings of Fifth International Workshop on. Neutrino-Nucleus Interactions in the Few-GeV Region. May 30, 2007 - June 3, 2007. Fermilab, Batavia, Illinois US

Contribution of distribution network control to voltage stability: A case study

A case study dealing with long-term voltage instability in systems hosting active distribution networks (DN) is reported in this paper. It anticipates future situations with high penetration of dispersed generation (DG), where the latter are used to keep distribution voltages within desired limits, in complement to load tap changers. The interactions between transmission and active DN are investigated on a 3108-bus test system. It involves transmission grid, large generators, and 40 DN, each with DG steered by a controller inspired by model predictive control. The reported simulations show the impact of distribution network voltage restoration, as well as the benefit of load voltage reduction actuated by the dispersed generators

First record of Rachiplusia nu (Lepidoptera: Noctuidae) as host of the egg parasitoid Trichogramma bruni (Hymenoptera: Trichogrammatidae).

Autoria: QUERINO [i.e. SILVA], R. B. Q. da. RANYSE BARBOSA QUERINO DA SILVA

N-Delta(1232) axial form factors from weak pion production

The N-Delta axial form factors are determined from neutrino induced pion production ANL & BNL data by using a state of the art theoretical model, which accounts both for background mechanisms and deuteron effects. We find violations of the off diagonal Goldberger-Treiman relation at the level of 2 sigma which might have an impact in background calculations for T2K and MiniBooNE low energy neutrino oscillation precision experiments.Comment: 4 pages, 1 figur

Hole burning in a nanomechanical resonator coupled to a Cooper pair box

We propose a scheme to create holes in the statistical distribution of excitations of a nanomechanical resonator. It employs a controllable coupling between this system and a Cooper pair box. The success probability and the fidelity are calculated and compared with those obtained in the atom-field system via distinct schemes. As an application we show how to use the hole-burning scheme to prepare (low excited) Fock states.Comment: 7 pages, 10 figure

U-Pb dating of Ordovician felsic volcanism in the Schistose Domain of the Galicia-Trás-os-Montes Zone near Cabo Ortegal (NW Spain)

The northern termination of the Schistose Domain of the Galicia-Trás-os-Montes Zone is a tectonic slice named the Rio Baio Thrust Sheet, which is sandwiched between the Cabo Ortegal Complex and the Ollo de Sapo Domain of the Central-Iberian Zone. The Rio Baio Thrust Sheet is formed by two volcanosedimentary series, the Loiba and the Queiroga Series. The Loiba Series contains calc-alkaline dacite and rhyolite, while the overlying Queiroga Series has alkaline rhyolite. These series were considered to be in stratigraphically upwards continuity and believed to be Silurian in age. U-Pb dating of an alkaline rhyolite in the Queiroga Series provides an Arenig age of 475 ± 2 Ma. This age makes the Queiroga Series the oldest known stratigraphic unit in the Schistose Domain of the Galicia-Trás-os-Montes Zone, impeding correlation between the lithostratigraphic sequences of Ortegal and Central Galicia. As well as providing evidence of an unforeseen structural complexity within the Rio Baio Sheet, the new data supports the notion that the Schistose Domain is not parautochtonous, but a separate lithotectonic unit in thrust contact with the underlying Central-Iberian Zone

Modelo numérico de cavitación para geometrías sencillas utilizando FLUENT V6.1

Cavitation is a phenomenon that can be present in several agro-forestry applications such as irrigation pressure-reducing valves, sprinkler orifices or even in the flow through xylem vessels inside plants. In the present research, numerical predictions of cavitation in a series of orifices, nozzles and venturis were compared to experimental measurements to show the possibilities and performances of the new cavitation model in the commercial Computational Fluid Dynamics (CFD) code FLUENT V6.1. A flashing study is also presented for the nozzle case. Model predictions for the orifice cases accurately capture cavitation inception and its influence on the orifice discharge coefficient. However, when an unsteady flow is modeled, the cavitation phenomenon is not simulated properly and leads to a steady situation. In general, the new cavitation model in FLUENT V6.1 provides very reliable simulation for easy geometries when steady flow is assumed.Los procesos de cavitación tienen relevancia en diferentes aspectos del área agroforestal, como en válvulas reductoras de presión para riego, chorros en aspersores e incluso en el flujo de savia en el xilema de las plantas. En este trabajo se ha validado el nuevo modelo de cavitación incluido en el programa comercial de mecánica de fluidos computacional FLUENT V6.1 en varios orificios, estrechamientos y venturis, comparando los resultados experimentales con los obtenidos por el modelo. También se presenta un estudio del fenómeno "flashing" producido en el estrechamiento. Las predicciones del modelo en el caso de los orificios muestran una buena estimación del momento de inicio de la cavitación así como de su desarrollo, estimado con el coeficiente de descarga del orificio. Sin embargo, cuando se trata de modelar el flujo en estado no estacionario, el proceso de cavitación no es simulado correctamente conduciendo a una situación estacionaria. De todo ello podemos concluir que el nuevo modelo de cavitación simula adecuadamente la cavitación en el flujo a través de geometrías sencillas, como los orificios y estrechamientos, en estado estacionario