1,549 research outputs found

    Neutrino Decay and Atmospheric Neutrinos

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    We reconsider neutrino decay as an explanation for atmospheric neutrino observations. We show that if the mass-difference relevant to the two mixed states \nu_\mu and \nu_\tau is very small (< 10^{-4} eV^2), then a very good fit to the observations can be obtained with decay of a component of \nu_\mu to a sterile neutrino and a Majoron. We discuss how the K2K and MINOS long-baseline experiments can distinguish the decay and oscillation scenarios.Comment: 9 pages, Revtex, uses epsf.sty, 3 postscript figures. Additions and corrections to references, minor changes in the text and to some number

    A Minimal Object Oriented Real-Time Operating System in C++

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    Most embedded software is currently developed using the C programming language, even though its low level of abstrac- tion requires a lot of effort to the programmer. The C++ language is a better choice because: it raises the level of abstraction; it is strongly typed, so it prevents many com- mon programming mistakes; it can be made as efficient as C through fine-grained customisation of memory mechanisms; it can be easily adapted to domain-specific needs. In ad- dition, recent compilers have grown in maturity and per- formance, and the new standard considerably improves the language by introducing new concepts and an easier syntax. In this paper we present ADOK, a minimal Real-Time Op- erating System entirely written in C++ with the exception of a few lines of assembler code. It directly offers a C++ interface to the developer, and it provides a flexible schedul- ing framework which allows the developer to customise the scheduling to its needs. In particular, we implement a two- level scheduler based on Earliest Deadline First, the Stack Resource Policy protocol for sharing resources and support for mode changes. We demonstrate through examples and a small case-study that ADOK can substantially improve productivity without sacrificing on performance

    Online regenerator placement.

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    Connections between nodes in optical networks are realized by lightpaths. Due to the decay of the signal, a regenerator has to be placed on every lightpath after at most d hops, for some given positive integer d. A regenerator can serve only one lightpath. The placement of regenerators has become an active area of research during recent years, and various optimization problems have been studied. The first such problem is the Regeneration Location Problem (Rlp), where the goal is to place the regenerators so as to minimize the total number of nodes containing them. We consider two extreme cases of online Rlp regarding the value of d and the number k of regenerators that can be used in any single node. (1) d is arbitrary and k unbounded. In this case a feasible solution always exists. We show an O(log|X| ·logd)-competitive randomized algorithm for any network topology, where X is the set of paths of length d. The algorithm can be made deterministic in some cases. We show a deterministic lower bound of W([(log(|E|/d) ·logd)/(log(log(|E|/d) ·logd))])log(Ed)logdlog(log(Ed)logd) , where E is the edge set. (2) d = 2 and k = 1. In this case there is not necessarily a solution for a given input. We distinguish between feasible inputs (for which there is a solution) and infeasible ones. In the latter case, the objective is to satisfy the maximum number of lightpaths. For a path topology we show a lower bound of Öl/2l2 for the competitive ratio (where l is the number of internal nodes of the longest lightpath) on infeasible inputs, and a tight bound of 3 for the competitive ratio on feasible inputs

    Determining the sign of Δ31\Delta_{31} at long baseline neutrino experiments

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    Recently it is advocated that high intensity and low energy (Eν∼2GeV)(E_\nu \sim 2 GeV) neutrino beams should be built to probe the (13)(13) mixing angle ϕ\phi to a level of a few parts in 10410^4. Experiments using such beams will have better signal to background ratio in searches for νμ→νe\nu_\mu \to \nu_e oscillations. We propose that such experiments can also determine the sign of Δ31\Delta_{31} even if the beam consists of {\it neutrinos} only. By measuring the νμ→νe\nu_\mu \to \nu_e transitions in two different energy ranges, the effects due to propagation of neutrinos through earth's crust can be isolated and the sign of Δ31\Delta_{31} can be determined. If the sensitivity of an experiment to ϕ\phi is ϵ\epsilon, then the same experiment is automatically sensitive to matter effects and the sign of Δ31\Delta_{31} for values of ϕ≥2ϵ\phi \geq 2 \epsilon.Comment: Title changed and paper rewritten. 4 pages, 1 figure, revte

    Extreme Galactic-Winds and Starburst in IR Mergers and IR QSOs

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    We report -as a part of a long-term study of mergers and IR QSOs- detailed spectroscopic evidences for outflow (OF) and/or Wolf Rayet features in: (i) low velocity OF in the ongoing mergers NGC 4038/39 and IRAS 23128-5919; (ii) extreme velocity OF (EVOF) in the QSOs IRAS 01003-2238 and IRAS 13218+0552; (iii) OF and EVOF in a complete sample of ultra-luminous IR galaxies/QSOs ("The IRAS 1 Jy MKO-KPNO Survey", of 118 objects). We found EVOF in IRAS 11119+3257, 14394+5332, 15130+1958 and 15462-0450. The OF components detected in these objects were mainly associated to starburst processes: i.e., to galactic-winds generated in multiple type II SN explosions and massive stars. The EVOF were detected in objects with strong starburst plus obscured IR QSOs; which suggest that interaction of both processes could generate EVOF. In addition, we analyze the presence of Wolf Rayet features in the large sample of Bright PG-QSOs (Boroson and Green 1992), and nearby mergers and galactic-wind galaxies. We found clear WR features in the Fe II QSOs (type I): PG 1244+026, 1444+407, 1448+273, 1535+547; and in the IR merger Arp 220. HST archive images of IR+BAL QSOs show in practically all of these objects "arc or shell" features probably associated to galactic-winds (i.e., to multiple type II SN explosions) and/or merger processes. Finally, we discuss the presence of extreme starburst and galactic wind as a possible evolutive link between IR merger and IR QSOs; where the relation between mergers and extreme starburst (with powerful galactic-winds) plays in important role, in the evolution of galaxies.Comment: 14 pages, 6 figure

    Industrial-scale wind energy in Italian southern Apennine: territorio grabbing, value extraction and democracy

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    This paper analyses the penetration of industrial-scale wind energy in the south Italy provinces of Benevento, Avellino, Foggia and Potenza, which host 43 per cent of national installed capacity. Such a process has induced transformations affecting (i) historical contextualised socio-ecological patterns as a consequence of their inclusion into value extraction chains and (ii) substantive democratic dynamics at the local level. The underlying theoretical framework interprets the green economy or green capitalism as a transformation of capitalism mode of regulation in accordance with ecological modernisation theories. More precisely, it fits into the political ecology debate around extractivism, primitive accumulation, land grabbing and environmentality. The paper develops by first giving an account of the investment penetration, then describing extractive mechanisms in terms of practices and actors. The last two sections explore effects of such processes on territorial democracy and propose the concept of ‘territorio’ grabbing as an analytical innovation

    The emission spectrum of the strong Fe II emitter BAL Seyfert 1 galaxy IRAS 07598+6508

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    The narrow-line Seyfert 1 galaxy IRAS 07598+6508 is known to be a stong Fe II emitter. The analysis of several high S/N ratio spectra shows that its spectrum is dominated by a relatively narrow "broad line" region (1 780 km s−1^{-1} FWHM) emitting not only Fe II, but also Ti II and Cr II lines. Although we were unable to find a completely satisfactory physical model, we got the best agreement with the observations with collisional rather than radiative models, with a high density (n=1015^{15} cm−3^{-3}), a high column density (NH_{H}=1025^{25} cm−2^{-2}) and a microturbulence of 100 km s−1^{-1}. This BLR is qualitatively similar to the one observed in I Zw 1. We have not found traces in IRAS 07598+6508 of the narrow line regions found in I Zw 1.Comment: 15 pages, 4 figures, accepted by A&

    Electronic structure and identification of deep defects in GaP

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