Dynamics and control of the expansion of finite-size plasmas produced in ultraintense laser-matter interactions

The strong influence of the electron dynamics provides the possibility of controlling the expansion of laser-produced plasmas by appropriately shaping the laser pulse. A simple irradiation scheme is proposed to tailor the explosion of large deuterium clusters, inducing the formation of shock structures, capable of driving nuclear fusion reactions. Such a scenario has been thoroughly investigated, resorting to two- and three-dimensional particle-in-cell simulations. Furthermore, the intricate dynamics of ions and electrons during the collisionless expansion of spherical nanoplasmas has been analyzed in detail using a self-consistent ergodic-kinetic model. This study clarifies the transition from hydrodynamic-like to Coulomb-explosion regimes

¿Cómo monitorear el movimiento del ganado en un mosaico de áreas boscosas con GPS en combinación con SIG?

El manejo de bosques de Piñon-Juniper (PJ) ocupa más de 30 millones de hectáreas en el oeste de Estados Unidos. Este ecosistema constituye un importante recurso para la producción y conservación de vida silvestre. Sin embargo, estos han cambiado considerablemente los últimos 30 años, principalmente para manejar ganado en pastoreo. El objetivo fue determinar la cobertura de dosel (TCC) y monitorear, durante la primavera, el uso del ganado del paisaje arbolado. El estudio se realizó en una pastura de 146 ha de la zona central de Nuevo México. La TCC de PJ se determinó a partir de ortofotos digitales recientes usando Feature Analyst® para ArcGIS® 9.1. El sitio de estudio fue segmentado en celdas de 1 ha para mapear cobertura arbórea. Ocho vacas, equipadas con GPS, fueron rastreadas durante 31 días a intervalos de 5 min. Una sección de la pastura con cobertura arbórea mayor que 30 % se utilizó para describir la relación distribución de pastoreo y cobertura de dosel. Se encontró una relación exponencial negativa significativa entre TCC y el uso relativo del ganado (y = 450,41e-12,329x). La cubierta arbórea explicó 50,1 % de la variación en la utilización relativa por el ganado de las celdas. La mayoría de las posiciones animales registradas en áreas dominadas por PJ ocurrieron en celdas con 30-50 % de TCC. Una cobertura del dosel de 50 % podría proporcionar un equilibrio adecuado entre la permanencia y el consumo de  forraje para el ganado durante la primavera

Expansion of nanoplasmas and laser-driven nuclear fusion in single exploding clusters

The expansion of laser-irradiated clusters or nanodroplets depends strongly on the amount of energy delivered to the electrons and can be controlled by using appropriately shaped laser pulses. In this paper, a self-consistent kinetic model is used to analyze the transition from quasineutral, hydrodinamic-like expansion regimes to the Coulomb explosion (CE) regime when increasing the ratio between the thermal energy of the electrons and the electrostatic energy stored in the cluster. It is shown that a suitable double-pump irradiation scheme can produce hybrid expansion regimes, wherein a slow hydrodynamic expansion is followed by a fast CE, leading to ion overtaking and producing multiple ion flows expanding with different velocities. This can be exploited to obtain intracluster fusion reactions in both homonuclear deuterium clusters and heteronuclear deuterium-tritium clusters, as also proved by three-dimensional molecular-dynamics simulations.Comment: 9 pages, 3 figures, to appear in Plasma Physics and Controlled Fusio

Bronze Age combustion structures of Italian contexts in comparison: Via Ordiere-Solarolo (Ravenna) and Mursia (Pantelleria island). Archaeological, geoarchaeological and experimental data

L’articolo prende in considerazione diverse fasi della ricerca relative all'uso del fuoco e alle pratiche di cottura in contesti domestici dell’età del Bronzo, utilizzando, per un approccio comparativo, le evidenze archeologiche rinvenute nei due insediamenti di Solarolo (RA) e di Mursia nell’isola di Pantelleria. Mentre nel primo caso l'evidenza delle strutture di cottura è scarsamente conservata e richiede campionamenti per analisi micromorfologiche e una complessa interpretazione, il secondo caso di Mursia, grazie alla migliore conservazione del deposito archeologico, permette di selezionare e ricostruire con maggiore facilità le caratteristiche coinvolte nella lavorazione e nella cottura dei cibi. Il contributo affronta il tema in modo altamente originale combinando diverse metodologie, raramente applicate nella descrizione delle strutture archeologiche connesse alla cottura dei cibi: oltre allo scavo stratigrafico documentato in dettaglio per la comprensione dei contesti sono state realizzate analisi micromorfologiche a sezione sottile, analizzate testimonianze etnoarcheologiche e applicate attività di riproduzione delle strutture e dei processi connessi alla produzione di alimenti cotti con metodi di archeologia sperimentale. Come richiesto dal processo scientifico dell’archeologia sperimentale sono illustrati in dettaglio i dati relativi alla costruzione delle strutture e al loro uso. Il contributo attende un ampio confronto nel dibattito sempre più intenso in ambito internazionale sulle attività svolte all’interno degli abitati protostorici e sui metodi di documentazione e analisi delle strutture archeologiche.Recent investigations carried out by the University of Bologna at the Bronze Age sites of Via Ordiere (Solarolo - Ravenna province) and Mursia (Pantelleria) discovered several types of fire installations. The paper considers different steps of the research related to the use of fire and cooking practices in domestic contexts using the two settlements for a comparative approach. While in the first case the evidence of firing structures is poorly pre-served and requires sampling for micromorphological analysis and complex analysis, the second case of Mursia, thanks to the best preservation of the archaeological deposit, allows to select and reconstruct more easily the features involved in processing and cooking food. Besides the presentation of the archaeological evidence, the research copes with the methods applied for a combination of results, including an archaeological protocol for documenting fire installations and the geo-archaeological analysis, extended to the comparison with similar features in the literature and with the ethno-archaeological evidence. A further approach was scheduled experimenting archaeological replica of most common fire installations. Finally, we deal a general understanding of the use of fire with a concept map going in depth with the many questions arisen pointing out the interrelationships among several parts of the process involving fire installations