Particle acceleration and transport during 3D CME eruptions

We calculate particle acceleration during coronal mass ejection (CME) eruptions using combined magnetohydrodynamic and test-particle models. The 2.5D/3D CMEs are generated via the breakout mechanism. In this scenario a reconnection at the "breakout" current sheet (CS) above the flux rope initiates the CME eruption by destabilizing a quasi-static force balance. Reconnection at the flare CS below the erupting flux rope drives the fast acceleration of the CME, which forms flare loops below and produces the energetic particles observed in flares. For test-particle simulations, two times are selected during the impulsive and decay phases of the eruption. Particles are revealed to be accelerated more efficiently in the flare CS rather than in the breakout CS even in the presence of large magnetic islands. Particles are first accelerated in the CSs (with or without magnetic islands) by the reconnection electric field mainly through particle curvature drift. We find, as expected, that accelerated particles precipitate into the chromosphere, become trapped in the loop top by magnetic mirrors, or escape to interplanetary space along open field lines. Some trapped particles are reaccelerated, either via reinjection to the flare CS or through a local Betatron-type acceleration associated with compression of the magnetic field. The energetic particles produce relatively hard energy spectra during the impulsive phase. During the gradual phase, the relaxation of magnetic field shear reduces the guiding field in the flare CS, which leads to a decrease in particle energization efficiency. Important implications of our results for observations of particle acceleration in the solar coronal jets are also discussed

Modeling a Coronal Mass Ejection from an Extended Filament Channel. I. Eruption and Early Evolution

We present observations and modeling of the magnetic field configuration, morphology, and dynamics of a large-scale, high-latitude filament eruption observed by the Solar Dynamics Observatory. We analyze the 2015 July 9-10 filament eruption and the evolution of the resulting coronal mass ejection (CME) through the solar corona. The slow streamer-blowout CME leaves behind an elongated post-eruption arcade above the extended polarity inversion line that is only poorly visible in extreme ultraviolet (EUV) disk observations and does not resemble a typical bright flare-loop system. Magnetohydrodynamic (MHD) simulation results from our data-inspired modeling of this eruption compare favorably with the EUV and white-light coronagraph observations. We estimate the reconnection flux from the simulation's flare-arcade growth and examine the magnetic-field orientation and evolution of the erupting prominence, highlighting the transition from an erupting sheared-arcade filament channel into a streamer-blowout flux-rope CME. Our results represent the first numerical modeling of a global-scale filament eruption where multiple ambiguous and complex observational signatures in EUV and white light can be fully understood and explained with the MHD simulation. In this context, our findings also suggest that the so-called stealth CME classification, as a driver of unexpected or "problem" geomagnetic storms, belongs more to a continuum of observable/nonobservable signatures than to separate or distinct eruption processes.Peer reviewe

The Large Imaging Spectrometer for Solar Accelerated Nuclei (LISSAN): A next-generation solar γ-ray spectroscopic imaging instrument concept

Models of particle acceleration in solar eruptive events suggest that roughly equal energy may go into accelerating electrons and ions. However, while previous solar X-ray spectroscopic imagers have transformed our understanding of electron acceleration, only one resolved image of γ-ray emission from solar accelerated ions has ever been produced. This paper outlines a new satellite instrument concept—the large imaging spectrometer for solar accelerated nuclei (LISSAN)—with the capability not only to observe hundreds of events over its lifetime, but also to capture multiple images per event, thereby imaging the dynamics of solar accelerated ions for the first time. LISSAN provides spectroscopic imaging at photon energies of 40 keV–100 MeV on timescales of ≲10 s with greater sensitivity and imaging capability than its predecessors. This is achieved by deploying high-resolution scintillator detectors and indirect Fourier imaging techniques. LISSAN is suitable for inclusion in a multi-instrument platform such as an ESA M-class mission or as a smaller standalone mission. Without the observations that LISSAN can provide, our understanding of solar particle acceleration, and hence the space weather events with which it is often associated, cannot be complete

The Utility of Exploiting Idle Workstations for Parallel Computation

In this paper, we examine the utility of exploiting idle workstations for parallel computation. We attempt to answer the following questions. First, given a workstation pool, for what fraction of time can we expect to find a cluster of k workstations available? This provides an estimate of the opportunity for parallel computation. Second, how stable is a cluster of free machines and how does the stability vary with the size of the cluster? This indicates how frequently a parallel computation might have to stop for adapting to changes in processor availability. Third, what is the distribution of workstation idle-times? This information is useful for selecting workstations to place computation on. Fourth, how much benefit can a user expect? To state this in concrete terms, if I have a pool of size S, how big a parallel machine should I expect to get for free by harvesting idle machines. Finally, how much benefit can be achieved on a real machine and how hard does a parallel programmer ha..

Sarcoma de Ewing: aspectos clínicos e radiográficos de 226 casos Ewing's sarcoma: clinical and radiographic aspects of 226 cases

OBJETIVO: Avaliar os aspectos radiográficos e clínicos presentes em pacientes com o diagnóstico de sarcoma de Ewing confirmado por histopatologia. MATERIAIS E MÉTODOS: Foram analisados, neste trabalho, os dados clínicos e radiográficos (quando disponíveis) de 226 pacientes com o diagnóstico de sarcoma de Ewing ósseo. RESULTADOS: Dos casos avaliados, 61,5% (139) eram do sexo masculino e 83,7% (189) eram brancos. A mediana de idade dos pacientes foi de 14 anos e a topografia mais freqüente das lesões foi o osso ilíaco, em 13,7% (31) dos casos. O aspecto radiográfico mais comum foi o de lesão lítica com reação periosteal (padrões variados), em 32,7% (74) dos casos. CONCLUSÃO: O sarcoma de Ewing ósseo é uma neoplasia bastante agressiva, ocorrendo mais comumente em indivíduos na segunda década de vida e cujo aspecto radiográfico mais comum é o de lesão lítica com reação periosteal típica de lesão agressiva.<br>OBJECTIVE: To review the clinical and radiographic findings in patients with histologically confirmed Ewing's sarcoma. MATERIALS AND METHODS: Clinical and radiological (whenever available) data of 226 patients with Ewing's sarcoma of the bone were analyzed. RESULTS: Of the evaluated cases, 61.5% (139) were male and 83.7% (189) were white. The average age was 14 years old and the most common site of the lesions was the iliac bone, seen in 13.7% (31) of the cases. The most common radiological findings were lytic lesion with periosteal reaction, seen in 32.7% (74) of the patients. CONCLUSION: Ewing's sarcoma of bone is an aggressive neoplasm, occurring mainly in the second decade of life, which main radiological findings are lytic lesions with periosteal reaction, typical characteristic of aggressive lesions

Membrane-Protein Binding Measured with Solution-Phase Plasmonic Nanocube Sensors

We describe a solution-phase sensor of lipid-protein binding based on localized surface plasmon resonance (LSPR) of silver nanocubes. When silica-coated nanocubes are mixed into a suspension of lipid vesicles, supported membranes spontaneously assemble on their surfaces. Using a standard laboratory spectrophotometer, we calibrate the LSPR peak shift due to protein binding to the membrane surface and then characterize the lipid-binding specificity of a pleckstrin-homology domain protein