Christoph Rau

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It is a long-held belief in evolutionary biology that the rate of molecular evolution for a given DNA sequence is inversely related to the level of functional constraint. This belief holds true for the protein-coding homeotic (Hox) genes originally discovered in Drosophila melanogaster. Expression of the Hox genes in Drosophila embryos is essential for body(More)
Imaging with hard X-rays allows visualizing cochlear structures while maintaining intrinsic qualities of the tissue, including structure and size. With coherent X-rays, soft tissues, including membranes, can be imaged as well as cells making use of the so-called in-line phase contrast. In the present experiments, partially coherent synchrotron radiation has(More)
Visually guided flight control in the rainforest is arguably one of the most complex insect behaviors: illumination varies dramatically depending on location [1], and the densely cluttered environment blocks out most of the sky [2]. What visual information do insects sample for flight control in this habitat? To begin answering this question, we determined(More)
We report an imaging scheme, termed aperture-scanning Fourier ptychography, for 3D refocusing and super-resolution macroscopic imaging. The reported scheme scans an aperture at the Fourier plane of an optical system and acquires the corresponding intensity images of the object. The acquired images are then synthesized in the frequency domain to recover a(More)
State-of-the-art techniques for phase retrieval in propagation based X-ray phase-contrast imaging are aiming to solve an underdetermined linear system of equations. They commonly employ Tikhonov regular-ization − an L2-norm regularized deconvolution scheme − despite some of its limitations. We present a novel approach to phase retrieval based on Total(More)
A method is proposed which enables the retrieval of the thickness or of the projected electron density of a sample from a single input image acquired with an edge illumination phase-contrast imaging setup. The method assumes the case of a quasi-homogeneous sample, i.e. a sample with a constant ratio between the real and imaginary parts of its complex(More)
Imaging of micro-and nano-structures of opaque samples is demonstrated using hard X-rays. Two different methods are employed with an instrument recently built at the beamline 34 ID-C at the Advanced Photon Source. In-line phase contrast micro-imaging has been performed with highly coherent radiation. For the characterisation of structures as small as 50 nm,(More)
An instrument for high-resolution imaging and tomography has been built at the APS beamline 34 ID-C, Argonne National Laboratory. In-line phase contrast tomography can be performed with micrometer resolution. For imaging and tomography with resolution better than 100nm a hard X-ray microscope has been integrated to the instrument. It works with a(More)
The magnetic order and critical behavior at well-defined surfaces of ultrathin (1.9-2.1) monolayer Fe{ lOO)p(1 X 1) films, deposited at room temperature on atomically flat Pd(100) substrate crystals, is investigated using electron-capture spectroscopy { ECS). Ferromagnetic order sets in at a surface Curie temperature Tc,=613.1 K. At room temperature, the(More)
Bulk metallic glass matrix composites (BMGMCs) are a new class of metal alloys which have significantly increased ductility and impact toughness, resulting from the ductile crystalline phases distributed uniformly within the amorphous matrix. However, the 3D structures and their morphologies of such composite at nano and micrometre scale have never been(More)