Marcel Müller

Open-source image reconstruction of super-resolution structured illumination microscopy data in ImageJ

Super-resolved structured illumination microscopy (SR-SIM) is an important tool for fluorescence microscopy. SR-SIM microscopes perform multiple image acquisitions with varying illumination patterns, and reconstruct them to a super-resolved image. In its most frequent, linear implementation, SR-SIM doubles the spatial resolution. The reconstruction is performed numerically on the acquired wide-field image data, and thus relies on a software implementation of specific SR-SIM image reconstruction algorithms. We present fairSIM, an easy-to-use plugin that provides SR-SIM reconstructions for a wide range of SR-SIM platforms directly within ImageJ. For research groups developing their own implementations of super-resolution structured illumination microscopy, fairSIM takes away the hurdle of generating yet another implementation of the reconstruction algorithm. For users of commercial microscopes, it offers an additional, in-depth analysis option for their data independent of specific operating systems. As a modular, open-source solution, fairSIM can easily be adapted, automated and extended as the field of SR-SIM progresses.

Nanoparticles as Nonfluorescent Analogues of Fluorophores for Optical Nanoscopy

Optical microscopy modalities that achieve spatial resolution beyond the resolution limit have opened up new opportunities in the biomedical sciences to reveal the structure and kinetics of biological processes on the nanoscale. These methods are, however, mostly restricted to fluorescence as contrast mechanism, which limits the ultimate spatial resolution and observation time that can be achieved by photobleaching of the fluorescent probes. Here, we demonstrate that Raman scattering provides a valuable contrast mechanism for optical nanoscopy in the form of super-resolution structured illumination microscopy. We find that nanotags, i.e., gold and silver nanoparticles that are capable of surface-enhanced Raman scattering (SERS), can be imaged with a spatial resolution beyond the diffraction limit in four dimensions alongside and with similar excitation power as fluorescent probes. The highly polarized nature of super-resolution structured illumination microscopy renders these nanotags elliptical in the reconstructed super-resolved images, which enables us to determine their orientation within the sample. The robustness of nanotags against photobleaching allows us to image these particles for unlimited periods of time. We demonstrate this by imaging isolated nanotags in a dense layer of fluorophores, as well as on the surface of and after internalization by osteosarcoma cells, always in the presence of fluorescent probes. Our results show that SERS nanotags have the potential to become highly multiplexed and chemically sensitive optical probes for optical nanoscopy that can replace fluorophores in applications where fluorescence photobleaching is prohibitive for following the evolution of biological processes for extended times.

Multifocus structured illumination microscopy for fast volumetric super-resolution imaging

We here report for the first time the synergistic implementation of structured illumination microscopy (SIM) and multifocus microscopy (MFM). This imaging modality is designed to alleviate the problem of insufficient volumetric acquisition speed in super-resolution biological imaging. SIM is a wide-field super-resolution technique that allows imaging with visible light beyond the classical diffraction limit. Employing multifocus diffractive optics we obtain simultaneous wide-field 3D imaging capability in the SIM acquisition sequence, improving volumetric acquisition speed by an order of magnitude. Imaging performance is demonstrated on biological specimens.

Temperature dependence of electrical conductivity and dilepton rates from hot quenched lattice QCD

Fakultat fur Physik, Universitat Bielefeld, D-33615 Bielefeld, GermanyE-mail: okacz@physik.uni-bielefeld.deWe present new results on the continuum extrapolation of the vector current correlation functionin the deconfined phase for three temperatures close to the critical temperature utilizing quenchedclover improved Wilson fermions and light quark masses. A systematic analysis on multiplelattice spacing allows to perform the continuum limit of the correlation function and to extractspectral properties in the continuum limit. These results provide constraints for the electricalconductivity and the thermal dilepton rates in the quark gluon plasma for the given temperaturerange. In addition results on the continuum extrapolation at finite momenta related to thermalphoton rates are presented.31st International Symposium on Lattice Field Theory - LATTICE 2013July 29 - August 3, 2013Mainz, Germany

The thermodynamic and the continuum limit of meson screening masses

We present results on the thermodynamic and continuum limit of meson screening masses in the deconfined phase, using standard staggered and non-perturbatively clover-improved Wilson fermions in the quenched approximation with light quark masses. For two temperatures, 1.5 Tc and 3.0 Tc, it is found that on finite lattices screening masses differ between the actions. We study if both actions reproduce the same masses in the continuum by employing different methods of extrapolation to the thermodynamic and continuum limit.

Characterization of an industry-grade CMOS camera well suited for single molecule localization microscopy – high performance super-resolution at low cost

Many commercial as well as custom-built fluorescence microscopes use scientific-grade cameras that represent a substantial share of the instrument’s cost. This holds particularly true for super-resolution localization microscopy where high demands are placed especially on the detector with respect to sensitivity, noise, and also image acquisition speed. Here, we present and carefully characterize an industry-grade CMOS camera as a cost-efficient alternative to commonly used scientific cameras. Direct experimental comparison of these two detector types shows widely similar performance for imaging by single molecule localization microscopy (SMLM). Furthermore, high image acquisition speeds are demonstrated for the CMOS detector by ultra-fast SMLM imaging.

Label-free Super-resolution Optical Microscopy of Cellular Dynamics

We demonstrate super-resolved structured illumination microscopy (SR-SIM) of Raman-active samples with 100 nm spatial resolution. By combining SR-SIM with coherent Raman scattering, even biological samples can be visualized with doubled spatial resolution.