Triangle-Free Penny Graphs: Degeneracy, Choosability, and Edge Count

We show that triangle-free penny graphs have degeneracy at most two, list coloring number (choosability) at most three, diameter $D=\Omega(\sqrt n)$, and at most $\min\bigl(2n-\Omega(\sqrt n),2n-D-2\bigr)$ edges.Comment: 10 pages, 2 figures. To appear at the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017

Doubly connected minimal surfaces and extremal harmonic mappings

The concept of a conformal deformation has two natural extensions: quasiconformal and harmonic mappings. Both classes do not preserve the conformal type of the domain, however they cannot change it in an arbitrary way. Doubly connected domains are where one first observes nontrivial conformal invariants. Herbert Groetzsch and Johannes C. C. Nitsche addressed this issue for quasiconformal and harmonic mappings, respectively. Combining these concepts we obtain sharp estimates for quasiconformal harmonic mappings between doubly connected domains. We then apply our results to the Cauchy problem for minimal surfaces, also known as the Bjorling problem. Specifically, we obtain a sharp estimate of the modulus of a doubly connected minimal surface that evolves from its inner boundary with a given initial slope.Comment: 35 pages, 2 figures. Minor edits, references adde

A multipurpose experimental facility for advanced X-ray Spectrometry applications

Ponencia presentada en la European Conference on X-Ray Spectrometry (EXRS). 2014Motivation, Ultra High Vacuum Chamber (UHVC) project: To support/enhance the training of scientists/engineers from developing countries in the operation of synchrotron radiation instrumentation; To provide beam time access for R&D projects and hands-on training in SR-XRS based techniques; To promote networking and knowledge sharing; To increase the quality and the competitiveness of the developing countries to apply beam time proposals at SR facilities; To contribute in the further development of XRS techniques in applications with socioeconomicalrelevance (characterization of energy storage/conversion materials, environmental, biological and biomedical applications)Fil: Leani, Juan José. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Leani, Juan José. Nuclear Science and Instrumentation Laboratory, IAEA Laboratories; Austria.Física Atómica, Molecular y Química (física de átomos y moléculas incluyendo colisión, interacción con radiación, resonancia magnética, Moessbauer Efecto.

Neuropathology of a case of dopa-responsive dystonia associated with a new genetic locus, DYT14.

Detailed autopsy findings are reported for a patient with dopa-responsive dystonia genetically related to the dopa-responsive dystonia locus DYT14 on chromosome 14q13. Substantia nigra and locus ceruleus showed a normal abundance of severely hypomelanized dopaminergic neurons and no Lewy body. In the nigra, the reduction of melanin pigment was found to be asymmetric between the two sides and uneven within neurons, and the lateral aspect of the nigra appeared more affected than the medial, in a pattern similar to the neuronal loss in PD. Dopa-responsive dystonia has a unique neuropathologic signature that seems to be independent of its genotype

A compact and efficient angle resolved X ray fluorescence spectrometer for elemental depth profiling

An angle resolved X ray fluorescence spectrometer based on the concept of scanning free shallow detection with energy dispersive area detectors is presented. The instrument is characterized with respect to energy resolution, linearity, angular discrimination and repeatability and the necessary data evaluation strategies are presented in detail. As demonstration of its capabilities and showcase for potential applications, two different copper indium gallium di selenide CIGS absorber layers, typically applied in thin film solar cells, are analyzed. In combination with quantitative but integral results for layer composition and layer thickness from a commercial XRF spectrometer, depth profiles of the Ga concentration of both amp; 8776; 2 amp; 956;m thin samples are obtained. The results of the novel spectrometer compare well with quantitative depth profiles obtained from glow discharge optical emission spectrometry. The combination of simplicity, stability and efficiency of the spectrometer concept makes it a potential candidate for industrial applications. Description of compact angle resolved X ray fluorescence spectrometer. Exploiting scanning free grazing emission X ray fluorescence approach. Energy dispersive charge coupled device with single photon detection. Enabling non destructive, quantitative elemental depth profiling. Depth profiling of nano structured stratified specimen, here CIGS solar cell

A laboratory spectrometer for high throughput X-ray emission spectroscopy in catalysis research

We have built a laboratory spectrometer for X-ray emission spectroscopy. The instrument is employed in catalysis research. The key component is a von Hamos full cylinder optic with Highly Annealed Pyrolytic Graphite (HAPG) as a dispersive element. With this very efficient optic, the spectrometer subtends an effective solid angle of detection of around 1 msr, allowing for the analysis of dilute samples. The resolving power of the spectrometer is approximately E/ΔE = 4000, with an energy range of ∼2.3 keV–10 keV. The instrument and its characteristics are described herein. Further, a comparison with a prototype spectrometer, based on the same principle, shows the substantial improvement in the spectral resolution and energy range for the present setup. The paper concludes with a discussion of sample handling. A compilation of HAPG fundamentals and related publications are given in a brief Appendix.EC/FP7/615414/EU/Spectroscopic Studies of N2 Reduction: From Biological to Heterogeneous Catalysis/N2RE

In situ gas cell for the analysis of adsorption behaviour on surfaces using X ray spectroscopy

A gas cell for in situ measurements of Volatile Organic Compounds VOCs and their adsorption behaviour on different surfaces by means of X ray Fluorescence XRF and X ray Absorption Fine Structure XAFS spectroscopy has been developed. The cell is especially designed to allow for the efficient excitation and detection of low Z elements such as carbon, oxygen or nitrogen as main components of VOCs. Two measurement modes are available. In the surface mode, adsorption on a surface can be studied using XAFS by fluorescence detection under shallow angles of incidence. The transmission mode enables the simultaneous investigation of gaseous samples via XAFS in transmittance and fluorescence detection modes. Proof of principle experiments were performed at the PTB plane grating monochromator beamline for soft X ray radiation at the synchrotron radiation facility BESSY II. The flexible design and high versatility of the cell are demonstrated with the investigation of ethanol EtOH as one of the most abundant VOCs. The comparison of Near Edge X ray Absorption Fine Structure NEXAFS spectra under transmission and fluorescence detection in the gas phase with measurements of adsorbed molecules on a Si wafer surface both at the C and O K absorption edges proves the applicability of the cell for the monitoring of adsorption processe