Robust Energy Calibration Technique for Photon Counting Spectral Detectors.

This paper describes the implementation of a novel and robust threshold energy calibration method for photon counting detectors using polychromatic X-ray tubes. Methods often used for such energy calibration may require re-orientation of the detector or introduce calibration errors that are flux and acquisition time-dependent. Our newly proposed "differential intensity ratios" (DIR) method offers a practical and robust alternative to existing methods. We demonstrate this robustness against photon flux used in calibration, spectral errors such as pulse pile-up as well as the detector's inherent spectral resolution limits. The demonstrated significant insensitivity of the proposed DIR signature to detector spectral distortions and energy resolution is a key finding. The proposed DIR calibration method is demonstrated using Medipix3RX detectors with a CdTe sensor under varying flux conditions. A per pixel calibration using the DIR method has also been implemented to demonstrate an improvement over the global energy resolution of the PCD.

Heat-induced coarsening of layer-by-layer assembled mixed Au and Pd nanoparticles.

This article shows the coarsening behavior of nanoparticle multilayers during heat treatments which produce larger metallic nanostructures with varying shapes and sizes on glass slides. Nanoparticle multilayer films are initially constructed via the layer-by-layer self-assembly of small and monodispersed gold and/or palladium nanoparticles with different compositions (gold only, palladium only, or both gold and palladium) and assembly orders (compounding layers of gold layers over palladium layers or vice versa). Upon heating the slides at 600°C, the surface nanoparticles undergo coalescence becoming larger nanostructured metallic films. UV-Vis results show a clear reliance of the layering sequence on the optical properties of these metal films, which demonstrates an importance of the outmost (top) layers in each nanoparticle multilayer films. Topographic surface features show that the heat treatments of nanoparticle multilayer films result in the nucleation of nanoparticles and the formation of metallic cluster structures. The results confirm that different composition and layering sequence of nanoparticle multilayer films clearly affect the coalescence behavior of nanoparticles during heat treatments.

Breve recuerdo histórico de la tuberculosis / Brief historical memory of tuberculosis

En pocas enfermedades es posible documentar su estrecha relación con la historia de la propia humanidad como en la que se ocupa; existen evidencias paleopatológicas de tuberculosis vertebral en restos neolíticos procolombinos, así como en momias egipcias que datan aproximadamente del año 2400 a. C.

Transplante renal: procedimientos médicos quirúrgicos principios bioéticos y aspectos legales

Sin duda alguna es una satisfacción personal presentar a todos los médicos y cirujanos que se dedican a la transplantología un texto guía de transplante renal y sus procedimientos, el cual consta de tres capítulos, el primero destinado a los aspectos generales del transplante renal, el segundo está dedicado a los principios bioéticos, los aspectos legales de la donación y transplante de órganos, células y tejidos