Abstract
We present radio and X-ray studies of A3444 and MS1455.0+2232, two galaxy clusters with radio minihalos in their cool cores. A3444 is imaged using the Giant Metrewave Radio Telescope (GMRT) ...at 333, 607, and 1300 MHz and the Very Large Array at 1435 MHz. Most of the minihalo is contained within
r
< 120 kpc, but a fainter extension, stretching out to 380 kpc southwest of the center, is detected at 607 MHz. Using Chandra, we detect four X-ray sloshing cold fronts: three in the cool core at
r
= 60, 120, and 230 kpc, and a fourth one at
r
= 400 kpc—in the region of the southwestern radio extension—suggesting that the intracluster medium (ICM) is sloshing on a cluster-wide scale. The radio emission is contained within the envelope defined by these fronts. We also analyzed archival 383 MHz GMRT and Chandra observations of MS 1455.0+2232, which exhibits a known minihalo with its bright part delineated by cold fronts inside the cool core, but with a faint extension beyond the core. Similarly to A3444, we find a cold front at
r
∼ 425 kpc, containing the radio emission. Thus the entire diffuse radio emission seen in these clusters appears to be related to large-scale sloshing of the ICM. The radio spectrum of the A3444 minihalo is a power law with a steep index
α
= 1.0 ± 0.1. The spectrum steepens with increasing distance from the center, as expected if the minihalo originates from reacceleration of relativistic particles by the sloshing-induced turbulence in the ICM.
We propose a new framework for design under uncertainty based on stochastic computer simulations and multi-level recursive co-kriging. The proposed methodology simultaneously takes into account ...multi-fidelity in models, such as direct numerical simulations versus empirical formulae, as well as multi-fidelity in the probability space (e.g. sparse grids versus tensor product multi-element probabilistic collocation). We are able to construct response surfaces of complex dynamical systems by blending multiple information sources via auto-regressive stochastic modelling. A computationally efficient machine learning framework is developed based on multi-level recursive co-kriging with sparse precision matrices of Gaussian-Markov random fields. The effectiveness of the new algorithms is demonstrated in numerical examples involving a prototype problem in risk-averse design, regression of random functions, as well as uncertainty quantification in fluid mechanics involving the evolution of a Burgers equation from a random initial state, and random laminar wakes behind circular cylinders.
A number of species for possible use as crops for fuel-ethanol production in Italy have been considered. These crops, namely sugarbeet, sweet sorghum, sugarcane, potato and grapevine, are such that ...experimentation at pilot plant level is already possible or nearly so. For each species, especially sugarbeet, cropping and produce characteristics as well as modification of agricultural practice, and by-products yield, are discussed in view of a possible ethanol production. The need for research on some points is emphasized. Possible expansion and distribution on the national territory is evaluated on the basis of soil and climate characteristics, of irrigation facilities and of relationship with other crops, taking also in account economic policy, as well as relationship with industry and consequences of practical interest.
ITALIANO: Si prendono in considerazione le specie di possibile utilizzazione come colture per la produzione di etanolo ad uso di carburante, limitandosi a quelle di particolare interesse per gli ambienti italiani che, per le stato delle conoscenze tecniche agronomiche ed industriali, siano pronte o poco lontane dalla fattibilita per una sperimentazione a livello di impianto pilota (bietola da zucchero, sorgo zuccherino, canna da zucchero, patata e vite). Si discutono per ciascuna di esse, e per la bietola in particolare, i problemi piu caratteristici della coltura e del prodotto ottenibile, le piu importanti modifiche di tecnica agronomica richieste da questa nuova eventuale finalita produttiva, nonche tipo e valore dei sottoprodotti ottenibili, mettendo in evidenza le esigenze di ricerca in determinate direzioni ed a diverso livello. Si esaminano poi le possibilita di estensione e di distribuzione delle colture da etanolo sul territorio italiano e della produzione ottenibile tenendo conto di fattori pedologici e climatici, di possibilita di irrigazione e di relazioni con le altre colture, inquadrando il problema anche nel contesto della politica economica, dei rapporti con l'industria e delle ripercussioni di varia natura di una eventuale iniziativa del genere.
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