The maximum angle condition is not necessary for convergence of the finite element method

We show that the famous maximum angle condition in the finite element analysis is not necessary to achieve the optimal convergence rate when simplicial finite elements are used to solve elliptic problems. This condition is only sufficient. In fact, finite element approximations may converge even though some dihedral angles of simplicial elements tend to π

Strategic and practical guidelines for successful structured illumination microscopy

Linear 2D- or 3D-structured illumination microscopy (SIM or3D-SIM, respectively) enables multicolor volumetric imaging of fixed and live specimens with subdiffraction resolution in all spatial dimensions. However, the reliance of SIM on algorithmic post-processing renders it particularly sensitive to artifacts that may reduce resolution, compromise data and its interpretations, and drain resources in terms of money and time spent. Here we present a protocol that allows users to generate high-quality SIM data while accounting and correcting for common artifacts. The protocol details preparation of calibration bead slides designed for SIM-based experiments, the acquisition of calibration data, the documentation of typically encountered SIM artifacts and corrective measures that should be taken to reduce them. It also includes a conceptual overview and checklist for experimental design and calibration decisions, and is applicable to any commercially available or custom platform. This protocol, plus accompanying guidelines, allows researchers from students to imaging professionals to create an optimal SIM imaging environment regardless of specimen type or structure of interest. The calibration sample preparation and system calibration protocol can be executed within 1-2 d

Measurement of low-mass e + e − pair production in 1 and 2 A GeV C–C collision with HADES

HADES is a secondary generation experiment operated at GSI Darmstadt with the main goal to study dielectron production in proton, pion and heavy ion induced reactions. The first part of the HADES mission is to reinvestigate the puzzling pair excess measured by the DLS collaboration in C+C and Ca+Ca collisions at 1A GeV. For this purpose dedicated measurements with the C+C system at 1 and 2A GeV were performed. The pair excess above a cocktail of free hadronic decays has been extracted and compared to the one measured by DLS. Furthermore, the excess is confronted with predictions of various model calculations. © 2009 Springer-Verlag / Società Italiana di Fisica. 62 1 81 84 Cited By :