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The energy at which collective transverse flow in the reaction plane disappears, the balance energy E bal , is found to depend on the isospin of the system using the reactions 58 Fe 1 58 Fe and 58 Ni 1 58 Ni. The more neutron-rich system exhibits higher balance energies for all measured impact parameters, in agreement with the predictions of a transport model which incorporates an isospin dependent mean field and isospin dependent in-medium nucleon-nucleon cross sections.[S0031-9007 (97)02358-2] PACS numbers: 25.70.Pq, 25.75.Ld

We present Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) observations of EUV cyclones in the quiet Sun. These cyclones are rooted in the rotating network magnetic fields (RNFs). Such cyclones can last several to more than 10 hr and, at the later phase, they are found to be associated with EUV brightenings (microflares) and even EUV waves. SDO Helioseismic and Magnetic Imager (HMI) observations show a ubiquitous presence of RNFs. Using HMI line-of-sight magnetograms on 2010 July 8, we find 388 RNFs in an area of 800 × 980 arcsec 2 near the disk center where no active region is present. The sense of rotation shows a weak hemisphere preference. The unsigned magnetic flux of the RNFs is about 4.0 × 10 21 Mx, or 78% of the total network flux. These observational phenomena at small scale reported in this Letter are consistent with those at large scale in active regions. The ubiquitous RNFs and EUV cyclones over the quiet Sun may suggest an effective way to heat the corona.

We present a comprehensive study of in situ electron acceleration during 74 shocks driven by interplanetary coronal mass ejections (ICMEs) with good suprathermal electron observations by the Wind 3DP instrument at 1 au from 1995 through 2014. Among the selected 59 quasi-perpendicular (15 quasi-parallel) shock cases, ∼86% (∼60%), ∼62% (∼36%), and ∼17% (∼7%) show significant electron flux enhancements of J D /J A  > 1.5 across the shock, respectively at 0.43, 1.95, and 40 keV, where J D and J A are the electron flux in the shock’s downstream and the preceding ambient solar wind. For significantly shocked suprathermal electrons, the differential flux J D positively correlates most with the magnetosonic Mach number M s , while the flux enhancement J D /J A positively correlates most with the magnetic compression ratio r B , among the shock parameters. Both J D and J A generally fit well to a double-power-law spectrum at ∼0.4–100 keV, J ∝ E −β , with an index of β 1 ∼ 2–6 below a break energy of E br (which is typically ∼2 keV) and an index of β 2 ∼ 2.0–3.2 at energies above. is similar to in all the shock cases, while is similar to (larger than) in ∼60% (∼40%) of the shock cases with significant electron enhancements. Furthermore, J D /J A mostly peaks in the directions perpendicular to the interplanetary magnetic field at ∼0.4–50 keV. These results suggest that both quasi-parallel and quasi-perpendicular shocks accelerate electrons in situ at 1 au mainly via shock drift acceleration, with an acceleration efficiency probably affected by the induced electric field at the shock surface.