Streaming H.264 scalable video over data distribution service in a wireless environment

The Data Distribution Service (DDS) middleware is enjoying a rapid adoption in high-performance, mission-critical networks. At the same time, the H.264 Scalable Video Coding (SVC) has been recently standardized and it is deemed to be an effective solution for video streaming over a channel with time-varying bandwidth, like the wireless one. In these conditions, it is critical to adapt the video bit-rate to the actual wireless capacity, and bit-rate adaptation is extremely simple for a H.264 SVC video. In this paper we devise, evaluate and demonstrate a technique for streaming H.264 SVC video over a DDS middleware. The contribution is threefold: i) we design a structure of the DDS data-unit able to carry H.264 SVC video-units; ii) we devise a receiver-driven rate-control mechanism based on our DDS data-unit and exploiting specific DDS functionality; iii) we implement and show the effectiveness of our mechanism in an 802.11 wireless scenario, comparing our proposal with other solution

Synchronisation and MSW sharpening of neutrinos propagating in a flavour blind medium

We consider neutrino oscillations in a medium in which scattering processes are blind to the neutrino flavour. We present an analytical derivation of the synchronised behaviour obtained in the limit where the average scattering rate is much larger than the oscillation frequency. We also examine MSW transitions in these circumstances, and show that a sharpening of the transition can result.Comment: 8 pages, 3 figures, accepted for publication in Phys. Lett.

Shock Breakout in Core-Collapse Supernovae and its Neutrino Signature

(Abridged) We present results from dynamical models of core-collapse supernovae in one spatial dimension, employing a newly-developed Boltzmann neutrino radiation transport algorithm, coupled to Lagrangean hydrodynamics and a consistent high-density nuclear equation of state. We focus on shock breakout and its neutrino signature and follow the dynamical evolution of the cores of 11 M_sun, 15 M_sun, and 20 M_sun progenitors through collapse and the first 250 milliseconds after bounce. We examine the effects on the emergent neutrino spectra, light curves, and mix of species of artificial opacity changes, the number of energy groups, the weak magnetism/recoil corrections, nucleon-nucleon bremsstrahlung, neutrino-electron scattering, and the compressibility of nuclear matter. Furthermore, we present the first high-resolution look at the angular distribution of the neutrino radiation field both in the semi-transparent regime and at large radii and explore the accuracy with which our tangent-ray method tracks the free propagation of a pulse of radiation in a near vacuum. Finally, we fold the emergent neutrino spectra with the efficiencies and detection processes for a selection of modern underground neutrino observatories and argue that the prompt electron-neutrino breakout burst from the next galactic supernova is in principle observable and usefully diagnostic of fundamental collapse/supernova behavior. Though we are not in this study focusing on the supernova mechanism per se, our simulations support the theoretical conclusion (already reached by others) that spherical (1D) supernovae do not explode when good physics and transport methods are employed.Comment: 16 emulateapj pages, plus 24 postscript figures, accepted to The Astrophysical Journal; text revised; neutrino oscillation section expanded; Fig. 22 correcte

High-resolution measurements of the exited states (n,pn), (n,dn) C-12 cross sections

Measurements of C12 cross sections for the excited states (n,p 0 ) up to (n,p 4 ) and (n,d 0 ), (n,d 1 ) have been carried out. The Van de Graaff neutron generator of the EC-JRC-IRMM laboratory has been used for these measurements. A very thin tritiated target (263 μg/cm 2 ) was employed with deuteron beams energies impinging on the target in the range 2.5–4.0 MeV. Neutrons in the range 18.9–20.7 MeV were produced with an intrinsic energy spread of 0.2–0.25% FWHM. With such narrow neutron energy spread, using a high energy resolution device such as a single crystal diamond detector, several peaks from the outgoing charged particles produced by the (n,p n ), (n,d n ) and also (n,α 0 ) reactions appear in the pulse height spectrum. The peaks can be identified using the reaction Q-values. The diamond detector used for these measurements has shown an intrinsic energy resolution lower than 0.9% FWHM. The analysis of the peaks has permitted to derive the partial carbon reaction cross sections for several excited states. The results are presented in this paper with the associated uncertainties and they are compared with different versions of TENDL compilation when these data are available (e.g. versions 2009, 2010, 2011 and 2015) and also with experimental results available in the EXFOR database

Modeling Adaptation with Klaim

In recent years, it has been argued that systems and applications, in order to deal with their increasing complexity, should be able to adapt their behavior according to new requirements or environment conditions. In this paper, we present an investigation aiming at studying how coordination languages and formal methods can contribute to a better understanding, implementation and use of the mechanisms and techniques for adaptation currently proposed in the literature. Our study relies on the formal coordination language Klaim as a common framework for modeling some well-known adaptation techniques: the IBM MAPE-K loop, the Accord component-based framework for architectural adaptation, and the aspect- and context-oriented programming paradigms. We illustrate our approach through a simple example concerning a data repository equipped with an automated cache mechanism

Analysis of Italian isolates of Pantoea stewartii subsp. stewartii and development of a real-time PCR-based diagnostic method

Pantoea stewartii subsp. stewartii (Pss) causes Stewart's vascular wilt of maize, and it is responsible for serious crop losses. Pss is indigenous to North America and spreads with maize seeds. The presence of Pss has been notified in Italy since 2015. The risk assessment of the entry of Pss in the EU from the United States through seed trade is in the order of magnitude of hundred introductions per year. Several molecular or serological tests were developed for the detection of Pss and used as official analysis for the certification of commercial seeds. However, some of these tests lack adequate specificity, not allowing to correctly discriminate Pss from P. stewartii subsp. indologenes (Psi). Psi is occasionally present in maize seeds and is avirulent for maize. In this study, several Italian isolates of Pss recovered in 2015 and 2018 have been characterized by molecular, biochemical, and pathogenicity tests; moreover, their genomes have been assembled through MinION and Illumina-sequencing procedures. Genomic analysis reveals multiple introgression events. Exploiting these results, a new primer combination has been defined and verified by real-time PCR, allowing the development of a specific molecular test able to detect the presence of Pss down to the concentration of 103  CFU/ml in spiked samples of maize seed extracts. Due to the high analytical sensitivity and specificity achieved with this test, the detection of Pss has been improved disentangling the inconclusive results in Pss maize seed diagnosis, overcoming its misidentification in place of Psi. Altogether, this test addresses the critical issue associated with maize seeds imported from regions where Stewart's disease is endemic

The MSW effect in a fluctuating matter density

We consider the effect on matter-enhanced neutrino flavor transformation of a randomly fluctuating, delta-correlated matter density. The fluctuations will produce a distribution of neutrino survival probabilities. We find the mean and variance of the distribution for the case of solar neutrinos, and discuss the possibility of placing a limit on solar density fluctuations using neutrino data.Comment: 20 LaTeX pages plus 24 Postscript figures; submitted to Phys. Rev. D; also available at http://nucth.physics.wisc.edu/preprints/mad-nt-96-01.tar.g