A Comprehensive Method of Estimating Electric Fields from Vector Magnetic Field and Doppler Measurements

Photospheric electric fields, estimated from sequences of vector magnetic field and Doppler measurements, can be used to estimate the flux of magnetic energy (the Poynting flux) into the corona and as time-dependent boundary conditions for dynamic models of the coronal magnetic field. We have modified and extended an existing method to estimate photospheric electric fields that combines a poloidal-toroidal (PTD) decomposition of the evolving magnetic field vector with Doppler and horizontal plasma velocities. Our current, more comprehensive method, which we dub the "{\bf P}TD-{\bf D}oppler-{\bf F}LCT {\bf I}deal" (PDFI) technique, can now incorporate Doppler velocities from non-normal viewing angles. It uses the \texttt{FISHPACK} software package to solve several two-dimensional Poisson equations, a faster and more robust approach than our previous implementations. Here, we describe systematic, quantitative tests of the accuracy and robustness of the PDFI technique using synthetic data from anelastic MHD (\texttt{ANMHD}) simulations, which have been used in similar tests in the past. We find that the PDFI method has less than $1$ error in the total Poynting flux and a $10$ error in the helicity flux rate at a normal viewing angle $(\theta=0$) and less than $25$ and $10$ errors respectively at large viewing angles ($\theta<60^\circ$). We compare our results with other inversion methods at zero viewing angle, and find that our method's estimates of the fluxes of magnetic energy and helicity are comparable to or more accurate than other methods. We also discuss the limitations of the PDFI method and its uncertainties.Comment: 56 pages, 10 figures, ApJ (in press

Community Partnerships for Cultural Participation: Concepts, Prospects, and Challenges

Evaluates the first year of the Wallace Foundation's Community Partnerships for Cultural Participation Initiative, which funded nine community foundations working to increase participation in the arts and culture in their communities

Photospheric Electric Fields and Energy Fluxes in the Eruptive Active Region NOAA 11158

How much electromagnetic energy crosses the photosphere in evolving solar active regions? With the advent of high-cadence vector magnetic field observations, addressing this fundamental question has become tractable. In this paper, we apply the "PTD-Doppler-FLCT-Ideal" (PDFI) electric field inversion technique of Kazachenko et al. (2014) to a 6-day HMI/SDO vector magnetogram and Doppler velocity sequence, to find the electric field and Poynting flux evolution in active region NOAA 11158, which produced an X2.2 flare early on 2011 February 15. We find photospheric electric fields ranging up to $2$ V/cm. The Poynting fluxes range from $[-0.6$ to $2.3]\times10^{10}$ ergs$\cdot$cm$^{-2}$s$^{-1}$, mostly positive, with the largest contribution to the energy budget in the range of $[10^9$-$10^{10}]$ ergs$\cdot$cm$^{-2}$s$^{-1}$. Integrating the instantaneous energy flux over space and time, we find that the total magnetic energy accumulated above the photosphere from the initial emergence to the moment before the X2.2 flare to be $E=10.6\times10^{32}$ ergs, which is partitioned as $2.0$ and $8.6\times10^{32}$ ergs, respectively, between free and potential energies. Those estimates are consistent with estimates from preflare non-linear force-free field (NLFFF) extrapolations and the Minimum Current Corona estimates (MCC), in spite of our very different approach. This study of photospheric electric fields demonstrates the potential of the PDFI approach for estimating Poynting fluxes and opens the door to more quantitative studies of the solar photosphere and more realistic data-driven simulations of coronal magnetic field evolution.Comment: 51 pages, 10 figures, accepted by ApJ on August 11, 201

Reversibility of Red blood Cell deformation

The ability of cells to undergo reversible shape changes is often crucial to their survival. For Red Blood Cells (RBCs), irreversible alteration of the cell shape and flexibility often causes anemia. Here we show theoretically that RBCs may react irreversibly to mechanical perturbations because of tensile stress in their cytoskeleton. The transient polymerization of protein fibers inside the cell seen in sickle cell anemia or a transient external force can trigger the formation of a cytoskeleton-free membrane protrusion of micrometer dimensions. The complex relaxation kinetics of the cell shape is shown to be responsible for selecting the final state once the perturbation is removed, thereby controlling the reversibility of the deformation. In some case, tubular protrusion are expected to relax via a peculiar "pearling instability".Comment: 4 pages, 3 figure

Gene rearrangements in bone marrow cells of patients with acute myelogenous leukemia

At diagnosis, clonal gene rearrangement probes {[}retinoic acid receptor (RAR)-alpha, major breakpoint cluster region (M-bcr), immunoglobulin (Ig)-JH, T cell receptor (TcR)-beta, myeloid lymphoid leukemia (MLL) or cytokine genes (GM-CSF, G-CSF, IL-3)] were detected in bone marrow samples from 71 of 153 patients with acute myelogenous leukemia (AML) (46%): in 41 patients with primary AML (pAML) (58%) and in 30 patients with secondary AML (42%). In all cases with promyelocytic leukemia (AML-M3) RAR-alpha gene rearrangements were detected (n = 9). Gene rearrangements in the Ig-JH or the TcR-beta or GM-CSF or IL-3 or MLL gene were detected in 12, 10, 16 and 12% of the cases, respectively, whereas only few cases showed gene rearrangements in the M-bcr (6%) or G-CSF gene (3%). Survival of pAML patients with TcR-beta gene rearrangements was longer and survival of pAML patients with IL-3 or GM-CSF gene rearrangement was shorter than in patients without those rearrangements. No worse survival outcome was seen in patients with rearrangements in the MLL, Ig-JH or M-bcr gene. In remission of AML (CR), clonal gene rearrangements were detected in 23 of 48 cases (48%) if samples were taken once in CR, in 23 of 26 cases (88%) if samples were taken twice in CR and in 23 of 23 cases (100%) if samples were studied three times in CR. All cases with gene rearrangements at diagnosis showed the same kind of rearrangement at relapse of the disease (n = 12). Our data show that (1) populations with clonal gene rearrangements can be regularly detected at diagnosis, in CR and at relapse of AML. (2) Certain gene rearrangements that are detectable at diagnosis have a prognostic significance for the patients' outcome. Our results point out the significance of gene rearrangement analyses at diagnosis of AML in order to identify `poor risk' patients - independently of the karyotype. Moreover, the persistence of clonal cells in the further course of AML can be studied by gene rearrangement analysis. Copyright (C) 2000 S. Karger AG, Basel