X-ray emission from accreting black holes

In this thesis I use state of the art models of x-ray emission from accreting black holes in order to observationally constrain the accretion geometry. The broad-band RXTE PCA and HEXTE spectrum of Cyg X-1 from 3 – 200keV is fit with reflection models which calculate the vertical ionization structure of an x-ray illuminated disc. Two geometries were considered corresponding to a truncated disc/inner hot flow and magnetic flares above an untruncated disc. Both models are able to fit the PCA 3 - 20keV data, but with very different spectral components. In the magnetic flare models the 3 - 20keV PCA spectrum contains a large amount of highly ionized reflection while in the truncated disc models the amount of reflection is rather small. The Compton downscattering rollover in the reflected emission means that the magnetic flare models predict a break in the spectrum at the high energies covered by the HEXTE bandpass which is not seen. By contrast the weakly illuminated truncated disc models can easily fit the 3 – 200keV spectra, strongly suggesting that this is the preferential geometry of galactic black hole binaries in the hard/low state

Unbounded dynamics in dissipative flows: Rössler model

Transient chaos and unbounded dynamics are two outstanding phenomena that dominate in chaotic systems with large regions of positive and negative divergences. Here, we investigate the mechanism that leads the unbounded dynamics to be the dominant behavior in a dissipative flow. We describe in detail the particular case of boundary crisis related to the generation of unbounded dynamics. The mechanism of the creation of this crisis in flows is related to the existence of an unstable focus-node (or a saddle-focus) equilibrium point and the crossing of a chaotic invariant set of the system with the weak-(un)stable manifold of the equilibrium point. This behavior is illustrated in the well-known Rössler model. The numerical analysis of the system combines different techniques as chaos indicators, the numerical computation of the bounded regions, and bifurcation analysis. For large values of the parameters, the system is studied by means of Fenichel's theory, providing formulas for computing the slow manifold which influences the evolution of the first stages of the orbit

Preparing for generation Z:how can technology enhanced learning be firmly embedded in our students' learning experience? A case study from Abertay University

Abertay is a relatively small, modern university (undergraduate population of around 4000) with a wide portfolio and a diverse student population. Around 35% of our students are direct entry from local partner colleges to years 2 and 3 of our programmes and a significant number are first generation higher education within their families. As such, partnership working with colleges and support to aid student transitions are key aspects of Abertay’s provision. Since 2013/14, the university has developed and implemented a new Teaching and Learning Enhancement strategy that has catalysed wholescale transformation across the institution. This paper provides an overview of technology enhanced learning at the university with the drivers for change being to the quality of our students' learning experience, improve student retention and progression and enhance learners’ engagement

Four-injector variability modeling of FinFET predictive technology models

The usual way of modeling variability using threshold voltage shift and drain current amplification is becoming inaccurate as new sources of variability appear in sub-22nm devices. In this work we apply the four-injector approach for variability modeling to the simulation of SRAMs with predictive technology models from 20nm down to 7nm nodes. We show that the SRAMs, designed following ITRS roadmap, present stability metrics higher by at least 20% compared to a classical variability modeling approach. Speed estimation is also pessimistic, whereas leakage is underestimated if sub-threshold slope and DIBL mismatch and their correlations with threshold voltage are not considered

Evolución paramétrica del sistema de Lorenz

En esta comunicación se estudia el comportamiento del sistema clásico de Lorenz en función de los tres par´ametros adimensionales del sistema utilizando indicadores de caos

De la interpretación geológica del paisaje a su expresión artística: el Curso de pintores pensionados de Segovia

Se pretende analizar e interpretar el reflejo que las actividades divulgativas geológicas que se realizan como complemento del “Curso de pintores pensionados de Paisaje”, tienen en la obra pictórica que realizan los alumnos del curso. Para ello se presentan cuáles son los contenidos de dichas actividades geológicas realizadas en siete ediciones del Curso (2006 y 2011-2016), se expone cómo se ha reflejado la temática geológica en la obra expuesta de los pintores; y se interpreta el porqué de los elementos más representados y cómo dichas enseñanzas geológicas son interiorizadas o no por los cursillistas a través de su obra. Con ello se pretende mejorar en el futuro el diseño y selección de contenidos de estas actividades, para conseguir que sean útiles y de interés para los pintores pensionados y su formación artística.Instituto Geológico y Minero de España, EspañaColegio Claret de Segovia, EspañaCurso de Pintura del Paisaje, Real Academia de Historia y Arte de San Quirce, Españ

El ingreso psiquiátrico involuntario de carácter urgente: una revisión, tras la STC 141/2012, de 2 de julio.

El internamiento psiquiátrico involuntario en España ha sido regulado con importantes carencias a través de la historia. Actualmente incluso existen importantes déficits sobre esta materia y existen también prácticas inadecuadas. Este artículo aborda estas cuestiones y, especialmente, analiza la reciente Sentencia del Tribunal Constitucional 141/2012, de 2 de julio, acerca del internamiento psiquiátrico involuntario por vía de urgencia. Esta Sentencia trata sobre las garantías de esta modalidad de ingreso, especialmente sobre plazos de la resolución judicial, motivación de la misma y derechos procesales del paciente. Sobre esta materia la sentencia es pionera

Reconfigurable writing architecture for reliable RRAM operation in wide temperature ranges

Resistive switching memories [resistive RAM (RRAM)] are an attractive alternative to nonvolatile storage and nonconventional computing systems, but their behavior strongly depends on the cell features, driver circuit, and working conditions. In particular, the circuit temperature and writing voltage schemes become critical issues, determining resistive switching memories performance. These dependencies usually force a design time tradeoff among reliability, device endurance, and power consumption, thereby imposing nonflexible functioning schemes and limiting the system performance. In this paper, we present a writing architecture that ensures the correct operation no matter the working temperature and allows the dynamic load of application-oriented writing profiles. Thus, taking advantage of more efficient configurations, the system can be dynamically adapted to overcome RRAM intrinsic challenges. Several profiles are analyzed regarding power consumption, temperature-variations protection, and operation speed, showing speedups near 700x compared with other published drivers

Experimental study of the effect of the thermal conductivity of EAF slag aggregates used in asphaltic concrete of wearing courses on the durability of road pavements

Electric Arc Furnace (EAF) steel slag is the basic material used to obtain good quality aggregates in different layers of road pavements. Many scientific papers have reported on the high frictional and abrasion resistance of this material. EAF slag aggregates are hard, dense, chemically stable and have good adhesion with bitumen, all characteristics related with its high alkaline character. These properties are important in hot mix asphalt for wearing courses where high wear is present and optimal skid resistance is required. In some EAF slags, calcium and specially magnesium oxides are not completely combined, and upon contact with moisture convert into the corresponding hydroxides that could lead to volume changes. Only EAF slags with less than 3,5% expansion are used in Europe as aggregates for asphalt concrete or hot mix asphalt. In this paper, we present the experimental results of a study evaluating the consequences of the lower thermal conductivity of the EAF slag aggregates used in Catalonia (Spain). These aggregates have the necessary mechanical and chemical properties, as well as a very low expansion (0,5 to 1,5%). The EAF slag aggregates have a lower thermal conductivity (0,85-1,20 W/mK) than natural aggregates, such as granite that are used in wearing courses (1,60-1,80 W/mK). This property of the EAF slag aggregates can represent up to 30% less conductivity in asphalt concrete or hot mix asphalt. The different levels of depth in the wearing course with slag aggregates will be at lower temperature. This is especially important during the spring, summer and early fall months in the interior territories of the Mediterranean Coast, when due to the high temperatures the modulus of the mix in the wearing course is lower. The layer containing EAF slag is stiffer and the pavement has a better ability to resist the tendency to develop ruts and deformations.Postprint (published version