Chern-Simons theory encoded on a spin chain

We construct a 1d spin chain Hamiltonian with generic interactions and prove that the thermal correlation functions of the model admit an explicit random matrix representation. As an application of the result, we show how the observables of $U(N)$ Chern-Simons theory on $S^{3}$ can be reproduced with the thermal correlation functions of the 1d spin chain, which is of the XX type, with a suitable choice of exponentially decaying interactions between infinitely many neighbours. We show that for this model, the correlation functions of the spin chain at a finite temperature $\beta =1$ give the Chern-Simons partition function, quantum dimensions and the full topological $S$-matrix.Comment: v2, 11 pages. Expanded, more detailed version. Misprints correcte

Improving Firmware Development Through the Rust Programming Language

ANSI-C and C++ have historically been the go-to option when developing embedded software but both languages lack memory security features which have been proven to be problematic by security standards. The Rust Programming Language has been pushed as a progressive alternative when security is a concern in firmware development and it has been shown its viability by the community and the industry.ITESO, A. C

Heroes and Villains in Watchmen

El objetivo de este Trabajo de fin de Grado es analizar una parte de la obra que es, casi universalmente considerada come el mejor comic que se ha escrito: Watchmen, creada por Alan Moore y Dave Gibbons. Este análisis se centrará en los personajes principales del comic, con el objetivo de examinar como encajan en los diferentes arquetipos tanto de villanos como de héroes. Para esto, se analizarán algunos de los arquetipos heroicos y de villanos más importantes de la literatura occidental, y esto se usará para analizar a los personajes del comic. El objetivo último de este análisis será probar que los personajes de un comic de superhéroes, normalmente considerado un género menor para adolescentes, también pueden ser increíblemente complejos.Departamento de Filología InglesaGrado en Estudios Inglese

The Decade 1989-1998 in Spanish Psychology: An Analysis of Research in Statistics, Methodology, and Psychometric Theory.

Sin resume

Estudio de la retención en membranas de nanofiltración mediante espectroscopía de impedancias

El objetivo de esta investigación consiste en el establecimiento de un método para la predicción de los valores de retención salina, para diversas sales (NaCl, KCl, MgCl2, CaCl2 y Na2SO4) que posee una membrana de nanofiltración. Aquí estudiamos la membrana Desal-HL. Para lograr dicho objetivo se ha hecho uso de la espectroscopia de impedancias. Esta técnica nos permite obtener la resistencia eléctrica que presenta nuestra membrana cuando contiene una disolución electrolítica confinada en el interior de sus poros. Para la obtención de los valores de resistencia del sistema membrana + disolución se modelizó nuestro sistema como un conjunto de capas, cada una de las cuales equivale a un elemento resistivo puro en paralelo a un elemento de fase constante (CPE) Además de las medidas de EIS se midió la permeabilidad salina que presentaba nuestra membrana de nanofiltración para todas las disoluciones electrolíticas. Esto se hizo mediante medidas del flujo salino causado por un gradiente de concentración. Por otra parte los valores de retención fueron tomados de la bibliografía existente. Finalmente se correlacionaron los resultados de resistencia eléctrica con los valores de permeabilidad y retención mostrando una correlación clara. En un futuro, el empleo de las correlaciones encontradas podría simplificar la medición de los valores de retención y permeabilidad mediante medidas de EIS, lo que permitiría la obtención de los parámetros de una manera más rápida y simple.Departamento de Física AplicadaMáster en Físic

Fitting logistic IRT models: small wonder.

Sin resume

Does time ever fly or slow down? The difficult interpretation of psychophysical data on time perception.

Time perception is studied with subjective or semi-objective psychophysical methods. With subjective methods, observers provide quantitative estimates of duration and data depict the psychophysical function relating subjective duration to objective duration. With semi-objective methods, observers provide categorical or comparative judgments of duration and data depict the psychometric function relating the probability of a certain judgment to objective duration. Both approaches are used to study whether subjective and objective time run at the same pace or whether time flies or slows down under certain conditions. We analyze theoretical aspects affecting the interpretation of data gathered with the most widely used semi-objective methods, including single-presentation and paired-comparison methods. For this purpose, a formal model of psychophysical performance is used in which subjective duration is represented via a psychophysical function and the scalar property. This provides the timing component of the model, which is invariant across methods. A decisional component that varies across methods reflects how observers use subjective durations to make judgments and give the responses requested under each method. Application of the model shows that psychometric functions in single-presentation methods are uninterpretable because the various influences on observed performance are inextricably confounded in the data. In contrast, data gathered with paired-comparison methods permit separating out those influences. Prevalent approaches to fitting psychometric functions to data are also discussed and shown to be inconsistent with widely accepted principles of time perception, implicitly assuming instead that subjective time equals objective time and that observed differences across conditions do not reflect differences in perceived duration but criterion shifts. These analyses prompt evidence-based recommendations for best methodological practice in studies on time perception

Is the DeVries-Rose to Weber Transition Empirically Possible with Sine-Wave Gratings?

Con frecuencia se ha medido la función visual a distintos niveles de iluminancia, bien determinando la agudeza visual para enrejados sinusoidales en función del nivel luminoso o bien determinando la forma en que la sensibilidad a enrejados sinusoidales cambia con la iluminancia. La primera vía de acercamiento ha revelado que la agudeza varía con la iluminancia de acuerdo con una función de dos ramas y un punto de discontinuidad en la transicion de visión escotópica a visión fotópica. Los resultados obtenidos a través de la segunda vía se han resumido aludiendo a una transición de la ley de DeVries-Rose a la de Weber, según la cual el logaritmo de la sensibilidad aumenta linealmente con pendiente 0.5 a medida que aumenta la iluminancia (para niveles bajos de iluminancia que comprenden el llamado rango de DeVries-Rose) pero luego permanece constante e invariante ante sucesivos incrementos de iluminancia (dentro del llamado rango de Weber). Aquí se evalúa la compatibilidad de los resultados obtenidos en estas dos líneas de investigación. Se parte de las restricciones empíricas impuestas por datos que revelan la forma de la superficie de sensibilidad a enrejados sinusoidales en función de la frecuencia espacial y la iluminancia, y se determina si esas restricciones son compatibles con la descripción que ofrecen las leyes de DeVries–Rose y Weber. El análisis muestra que la ley de DeVries-Rose sólo es posible empíricamente para enrejados sinusoidales de baja frecuencia.Visual functioning at various retinal illuminance levels is usually measured either by determining grating acuity as a function of light level or by determining how sensitivity to sine-wave gratings changes with retinal illuminance. The former line of research has shown that grating acuity follows a two-branch relationship with retinal illuminance, with the point of discontinuity occurring at the transition from scotopic to photopic vision. Results of the latter line of research have summarily been described as a transition from the DeVries-Rose law to Weber’s law, according to which log sensitivity increases linearly with log illuminance with a slope of 0.5 over a range of low illuminances (the DeVries-Rose range) and then levels off and does not increase with further increases of illuminance (the Weber range). This paper aims at determining the compatibility of the results of these two lines of research. We consider empirical constraints from data bearing on the shape of the surface describing contrast sensitivity to sine-wave gratings as a function of spatial frequency and illuminance simultaneously, in order to determine whether they are consistent with a summary description in terms of DeVries-Rose and Weber’s laws. Our analysis indicates that, with sine-wave gratings, the DeVries-Rose law can only hold empirically at low spatial frequencies

Quantum Steering and Space-Like Separation

In non-relativistic quantum mechanics, measurements performed by separate observers are modeled via tensor products. In Algebraic Quantum Field Theory, though, local observables corresponding to space-like separated parties are just required to commute. The problem of determining whether these two definitions of "separation" lead to the same set of bipartite correlations is known in non-locality as Tsirelson's problem. In this article, we prove that the analog of Tsirelson's problem in steering scenarios is false. That is, there exists a steering inequality that can be violated or not depending on how we define space-like separation at the operator level.Comment: Some typos corrected. Short discussion about Algebraic Quantum Field Theory. Modified introduction and conclusio