Temporal Evolution of the Magnetic Topology of the NOAA Active Region 11158

We studied the temporal evolution of the magnetic topology of the active region (AR) 11158 based on the reconstructed three-dimensional magnetic fields in the corona. The \nlfff\ extrapolation method was applied to the 12 minutes cadence data obtained with the \hmi\ (HMI) onboard the \sdo\ (SDO) during five days. By calculating the squashing degree factor Q in the volume, the derived quasi-separatrix layers (QSLs) show that this AR has an overall topology, resulting from a magnetic quadrupole, including an hyperbolic flux tube (HFT) configuration which is relatively stable at the time scale of the flare ($\sim 1-2$ hours). A strong QSL, which corresponds to some highly sheared arcades that might be related to the formation of a flux rope, is prominent just before the M6.6 and X2.2 flares, respectively. These facts indicate the close relationship between the strong QSL and the high flare productivity of AR 11158. In addition, with a close inspection of the topology, we found a small-scale HFT which has an inverse tear-drop structure above the aforementioned QSL before the X2.2 flare. It indicates the existence of magnetic flux rope at this place. Even though a global configuration (HFT) is recognized in this AR, it turns out that the large-scale HFT only plays a secondary role during the eruption. In final, we dismiss a trigger based on the breakout model and highlight the central role of the flux rope in the related eruption.Comment: Accepted by Ap

Effects of acid rain on competitive releases of Cd, Cu, and Zn from two natural soils and two contaminated soils in hunan, China

Leaching experiments of rebuilt soil columns with two simulated acid rain solutions (pH 4.6– 3.8) were conducted for two natural soils and two artificial contaminated soils from Hunan, southcentralChina, to study effects of acid rain on competitive releases of soil Cd, Cu, and Zn. Distilled water was used in comparison. The results showed that the total releases were Zn>Cu>Cd for the natural soils and Cd>Zn≫Cu for the contaminated soils, which reflected sensitivity of these metals to acid rain. Leached with different acid rain, about 26–76% of external Cd and 11–68% external Zn were released,but more than 99% of external Cu was adsorbed by the soils, and therefore Cu had a different sorption and desosption pattern from Cd and Zn. Metal releases were obviously correlated with releases of TOC in the leachates, witch could be described as an exponential equation.Compared with the natural soils,acid rain not only led to changes in total metal contents, but also in metal fraction distributions in the contaminated soils. More acidifed soils had a lower sorption capaity to metals, mostlt related to soil properties such as pH organic matter, soil particles, adsorbed SO42-, exchangeable AI3+ and H+, and contents of Fe2O3 and AI2O3

A Characterization of E

A class of vector optimization problems is considered and a characterization of E-Benson proper efficiency is obtained by using a nonlinear scalarization function proposed by Göpfert et al. Some examples are given to illustrate the main results