Reflexiones sobre What is Political Philosophy? de Leo Strauss

Sin resume

Acute Stroke Imaging

This presentation is part of the PEER Liberia Radiology Lecture Series. It provides an overview of imaging and stroke assessment for acute stroke, including a review of some cases

Reseña de la obra de Antonio Marquet, "El coloquio de las perras"

1 archivo PDF (10 páginas). fhquadragintatresReseña de la obra de Antonio Marquet “El coloquio de las perras” donde el autor explora una singular forma de violencia. La violencia del perreo al interior de la comunidad gay

Intercalation of sulfur in epitaxial graphene on ruthenium(0001) studied by means of scanning tunneling microsocopy and spectroscopy

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de lectura: 26 de febrero de 2016En esta tesis se estudia la interacción del sulfuro de hidrógeno (H2S) con el grafeno crecido epitaxialmente sobre el plano basal del rutenio (Ru(0001)). El crecimiento de las muestras y su caracterización se realizó mediante microscopía y espectroscopia de efecto túnel (STM/STS) en ultra alto vacío (UHV). Parte de la caracterización se realizó a baja temperatura y se utilizaron de manera complementaria otras técnicas de caracterización en UHV. El grafeno epitaxial sobre Ru(0001) (grafeno/Ru(0001)) se crece mediante descomposición catalítica de etileno en condiciones de UHV. El grafeno/Ru(0001) muestra una interacción intensa entre el grafeno y el sustrato que resulta en una modulación topográfica y electrónica en forma de patrón de moiré debido a la pequeña diferencia en el parámetro de red de ambos. El grafeno así crecido está fuertemente anclado al Ru(00001) y altamente dopado (tipo-n), perdiendo su carácter semimetálico y su característica relación de dispersión lineal. Las imágenes de STM demuestran que la exposición de grafeno/Ru(0001) a H2S resulta en la intercalación de azufre entre el grafeno y el sustrato. Los experimentos sugieren que se produce mediante la formación de defectos puntuales en la superficie del grafeno. Los átomos de azufre intercalados se estructuran formando diferentes reconstrucciones que son descritas y analizadas. Para complementar la descripción geométrica de las estructuras que forma el azufre intercalado, se han realizado experimentos de adsorción de azufre en Ru(0001) sin la capa de grafeno epitaxial. Las diferentes reconstrucciones de la capa de azufre intercalado en el sistema estudiado alteran las propiedades del grafeno que hay sobre ella. La densidad superficial de átomos de azufre y sus características geométricas reducen la interacción del grafeno con el Ru(0001) en diferente medida, como evidencia la reducción en la corrugación del patrón de moiré en los experimentos de STM. Para analizar en más detalle la influencia de las diferentes configuraciones del azufre sobre las propiedades del sistema se realizaron experimentos de STS a baja temperatura que muestran la aparición de una serie de resonancias equiespaciadas en torno al nivel de Fermi tras la exposición a H2S. El desplazamiento de estos picos a mayores energías con el aumento de la densidad de azufre sugiere la reducción del dopaje del grafeno intercalado con respecto al grafeno/Ru(0001). Su origen no ha podido ser establecido, pero se proponen posibles explicaciones para su aparición. Por último, se llevaron a cabo experimentos de manipulación de la superficie de grafeno/S/Ru(0001) utilizando la punta del STM. Cuando la densidad de la capa intercalada permite la movilidad del azufre se ha conseguido crear patrones geométricos desplazando los átomos intercalados de manera que se recupera la interacción entre el grafeno y el Ru(0001) en zonas concretas. Las estructuras así creadas tienen tamaños nanométricos y son estables a temperatura ambiente.This thesis studies the interaction of hydrogen sulfide (H2S) with graphene epitaxially grown on the basal plane of ruthenium (Ru(0001)). Sample growth and characterization is carried out by means of scanning tunneling microscopy and spectroscopy (STM/STS) in ultra-high vacuum (UHV) conditions. Part of the characterization was done at low temperature, and complementary UHV characterization techniques were also used. Epitaxial graphene on Ru(0001) (graphene/Ru(0001)) is grown by catalytic decomposition of ethylene in UHV conditions. Graphene/Ru(0001) shows a strong interaction between graphene and its substrate that results in a topographic and electronic modulation emerging as a moiré pattern due to the lattice mismatch between both materials. The resulting graphene layer is strongly bound to Ru(0001) and highly doped (n-type), losing its semi-metallic character and its characteristic linear dispersion relation. STM images show that exposing graphene/Ru(0001) to H2S results in the intercalation of sulfur between graphene and its substrate. The experiments suggest that intercalation occurs via the formation of local defects in the graphene’s surface. The intercalated sulfur atoms are structured forming different reconstructions which are described and analyzed. In order to complement the geometrical description of the intercalated sulfur layer, experiments on the adsorption of sulfur on Ru(0001) have been carried out. The different reconstructions of the intercalated system alter the properties of the graphene layer on top. The surface density of sulfur atoms and their geometrical characteristics reduce the interaction between graphene and Ru(0001) in different ways, as it is evident from the corrugation reduction of the moiré in STM experiments. In order to get a deeper insight on the influence of the geometrical configurations of sulfur on the system’s properties we performed low-temperature STS experiments. They show the emergence of a series of evenly spaced resonances close to the Fermi level after H2S exposure. The shift of these resonances towards higher energies with increasing sulfur density suggest the reduction of the doping of the intercalated graphene with respect to graphene/Ru(0001). Their origin is not clear, but some possible explanations are suggested. Lastly, manipulation experiments were carried out using the STM tip. When the density of the intercalated layer is low enough to allow for the sulfur mobility, geometric patterns have been drawn on the surface by moving the intercalated atoms in such a way that the strong graphene-Ru interaction is recovered at specific places. The so-created structures have lateral sizes in the nanometer range and are stable at room temperature

Novísima Relación. Narrativa amerispánica actual: estudio, selección y materiales complementarios por Daniel Mesa Gancedo.

"Esta Novísima relación viene a llenar un hueco que posiblemente pocos habían advertido explícitamente ―pese a la envergadura de su realidad― y a hacernos concientes de su importancia. Esto es: la narración de la experiencia transmigráfica hispanoamericana de las últimas décadas y, más concretamente, de los años 0...

Intercalation of sulfur in epitaxial graphene on ruthenium(0001) studied by means of scanning tunneling microscopy and spectroscopy

This thesis studies the interaction of hydrogen sulfide (H2S) with graphene epitaxially grown on the basal plane of ruthenium (Ru(0001)). Sample growth and characterization is carried out by means of scanning tunneling microscopy and spectroscopy (STM/STS) in ultra-high vacuum (UHV) conditions. Part of the characterization was done at low temperature, and complementary UHV characterization techniques were also used. Epitaxial graphene on Ru(0001) (graphene/Ru(0001)) is grown by catalytic decomposition of ethylene in UHV conditions. Graphene/Ru(0001) shows a strong interaction between graphene and its substrate that results in a topographic and electronic modulation emerging as a moiré pattern due to the lattice mismatch between both materials. The resulting graphene layer is strongly bound to Ru(0001) and highly doped (n-type), losing its semi-metallic character and its characteristic linear dispersion relation. STM images reveal that exposing graphene/Ru(0001) to H2S results in the intercalation of sulfur between graphene and its substrate. The experiments suggest that intercalation occurs via the formation of local defects on the graphene’s surface. The intercalated sulfur atoms are structured forming different reconstructions which are described and analyzed. In order to complement the geometrical description of the intercalated sulfur layer, experiments on the adsorption of sulfur on Ru(0001) have been carried out. The different reconstructions of the intercalated system alter the properties of the graphene layer on top. The surface density of sulfur atoms and their geometrical characteristics reduce the interaction between graphene and Ru(0001) in different ways, as is evident from the corrugation reduction of the moiré in STM experiments. In order to obtain a deeper insight on the influence of the geometrical configurations of sulfur on the system’s properties we performed low-temperature STS experiments. They show the emergence of a series of evenly spaced resonances close to the Fermi level after H2S exposure. The shift of these resonances towards higher energies with increasing sulfur density suggest the reduction of the doping of the intercalated graphene with respect to graphene/Ru(0001). The origin of this phenomenon is not clear, but some possible explanations are suggested. Lastly, atomic manipulation experiments were carried out using the STM tip. When the density of the intercalated layer is low enough to allow for mobility of the sulfur atoms, geometric patterns were drawn on the surface by moving the intercalated atoms in such a way that the strong graphene-Ru interaction is recovered at specific places

Carlo Milanuzzi's Quarto Scherzo and the Climate of Venetian Popular Music in the 1620s

Although music publishing in Italy was on the decline around the turn of the seventeenth century, Venice emerged as one of the most prolific publishing centers of secular song in Italy throughout the first three decades of the 1600s. Many Venetian song collections were printed with alfabeto, a chordal tablature designed to facilitate even the most untrained of musicians with the necessary tools for accompanying singers on the fashionable five-course Spanish guitar. Carlo Milanuzzi's Quarto Scherzo (1624) stands out among its contemporary Venetian song collections with alfabeto as an anthology of Venetian secular songs, including compositions by Miniscalchi, Berti, and Claudio and Francesco Monteverdi. Issues surrounding its publication, instrumentation, and musical and poetic style not only contribute to the understanding of Venetian Baroque monody, but also help to construe a repertory of vocal music with defining characteristics usually associated with popular music of the 19th, 20th, and 21st centuries