Path Integral Quantisation of Finite Noncommutative Geometries

We present a path integral formalism for quantising gravity in the form of the spectral action. Our basic principle is to sum over all Dirac operators. The approach is demonstrated on two simple finite noncommutative geometries: the two-point space, and the matrix geometry M_2(C). On the first, the graviton is described by a Higgs field, and on the second, it is described by a gauge field. We start with the partition function and calculate the propagator and Greens functions for the gravitons. The expectation values of distances are evaluated, and we discover that distances shrink with increasing graviton excitations. We find that adding fermions reduces the effects of the gravitational field. A comparison is also made with Rovelli's canonical quantisation approach, and with his idea of spectral path integrals. We include a brief discussion on the quantisation of a Riemannian manifold.Comment: 12 pages, LaTeX2e, significantly revised. This is the published version with some minor addition

Who drove the boom in euro-denominated bond issues?

We make use of micro-level data for over 45,000 private bonds issued by over 5000 firms from 22 countries in 1990-2006 to analyze the impact that the launch of the EMU had on the currency denomination of the bond issues. To our knowledge, ours is the first systematic analysis of issue at the micro level. The use of the micro data allows us to distinguish between the response to the advent of the euro by new and seasoned bond issuers, and to condition on other issue characteristics. We find that the impact on new issuers is larger than on seasoned issuers and that most of the increase in the euro-denominated bond issuance was along the "extensive" margin. Insofar as new entrants to the bond market will define the overall currency composition in the long run, these results imply that aggregate studies might be underestimating the euro effect. We also find that to a large extent the increase in euro issuance was "at the expense" of U.S. dollar issuance, suggesting that the euro competes with the U.S. dollar as a currency of choice for international financial transactions.Bond market ; Euro

Courage to Capital? A Model of the Effects of Rating Agencies on Sovereign Debt Role-over

We propose a model of rating agencies that is an application of global game theory in which heterogeneous investors act strategically. The model allows us to explore the impact of the introduction of a rating agency on financial markets. Our model suggests that the addition of the rating agency affects the probability of default and the magnitude of the response of capital flows to changes in fundamentals in a non–trivial way, and that introducing a rating agency can bring multiple equilibria to a market that otherwise would have the unique equilibrium.Credit rating, Rating agency, Sovereign debt, Global game

Developments in noncommutative differential geometry

One of the great outstanding problems of theoretical physics is the quantisation of gravity, and an associated description of quantum spacetime. It is often argued that, at short distances, the manifold structure of spacetime breaks down and is replaced by some sort of algebraic structure. Noncommutative geometry is a possible candidate for the mathematics of this structure. However, physical theories on noncommutative spaces are still essentially classical and need to be quantised. We present a path integral formalism for quantising gravity in the form of the spectral action. Our basic principle is to sum over all Dirac operators. The approach is demonstrated on two simple finite noncommutative geometries (the two-point space and the matrix geometry M(_2)(C)) and a circle. In each case, we start with the partition function and calculate the graviton propagator and Greens functions. The expectation values of distances are also evaluated. We find on the finite noncommutative geometries, distances shrink with increasing graviton excitations, while on a circle, they grow. A comparison is made with Rovelli's canonical quantisation approach, and with his idea of spectral path integrals. We also briefly discuss the quantisation of a general Riemannian manifold. Included, is a comprehensive overview of the homological aspects of noncommutative geometry. In particular, we cover the index pairing between K-theory and K-homology, KK-theory, cyclic homology/cohomology, the Chern character and the index theorem. We also review the various field theories on noncommutative geometries

Master of Science

thesisThe University of Utah Seismograph Stations recorded 293 earthquakes (3.0 < M < 5.9) between April 17, 2007 and June 30, 2012. During this time, four-element infrasound data were collected from three permanent (NOQ, BGU, and EPU; installed 2006 - 2007) and six temporary (BRP, WMU, HWU, FSU, LCM, and PSU; installed summer of 2010) seismo-acoustic arrays. Unique epicentral infrasound observations from nine earthquakes with M 3.6 - 5.9 are identified and characterized. The detections were recorded from normal, oblique normal, and strike-slip faulting earthquakes at distances of 156 - 695 km and depths of 5 - 12 km. We use ray-tracing through ground-to- space atmospheric models from the epicenters to each array to determine the atmospheric turning altitude and associated wind velocities. Distance and wind corrected amplitudes match previously determined scaling relations. However, the duration observations from smaller magnitude earthquakes suggest the possibility of an additional scaling relation for events M < 4.6. This possible change in duration scaling relation is inconsistent with the hypothesis that infrasound duration scales with the areal extent of the epicentral region subjected to a threshold peak ground acceleration. The predicted ground motions show that the area subject to the threshold increases more rapidly with increased magnitudes. Overall, the small percentage of infrasound detections from the total possible suggests that infrasound is not a robust method of detecting and characterizing small earthquake sources

A Digital-to-Analog Converter Architecture for Multi-Channel Applications

Systems-on-chip with the capability of driving multiple analog voltages are useful for a variety of applications, including multiple actuator control for robotics applications, automated test equipment systems, industrial automation, programmable logic controllers, and satellite ywheel motor control. Such applications require a DAC for each analog output. A multi-channel architecture that saves power and area by sharing hardware is needed. This work introduces a new single-ramp multi-channel 12-bit DAC architecture. The architecture includes a low power Gray code counter, ramp generator, digital comparator, analog memory units, and control logic. The new multi-channel DAC architecture allows hardware sharing between multiple channels, and enables Systems-on-Chip to have multiple analog outputs for stimulating transducers or motors. The DAC architecture is to be used in a variety of space and defense applications as part of the BAE Systems RAD6000 microcontroller project

Measuring relative opinion from location-based social media: A case study of the 2016 U.S. presidential election

Social media has become an emerging alternative to opinion polls for public opinion collection, while it is still posing many challenges as a passive data source, such as structurelessness, quantifiability, and representativeness. Social media data with geotags provide new opportunities to unveil the geographic locations of users expressing their opinions. This paper aims to answer two questions: 1) whether quantifiable measurement of public opinion can be obtained from social media and 2) whether it can produce better or complementary measures compared to opinion polls. This research proposes a novel approach to measure the relative opinion of Twitter users towards public issues in order to accommodate more complex opinion structures and take advantage of the geography pertaining to the public issues. To ensure that this new measure is technically feasible, a modeling framework is developed including building a training dataset by adopting a state-of-the-art approach and devising a new deep learning method called Opinion-Oriented Word Embedding. With a case study of the tweets selected for the 2016 U.S. presidential election, we demonstrate the predictive superiority of our relative opinion approach and we show how it can aid visual analytics and support opinion predictions. Although the relative opinion measure is proved to be more robust compared to polling, our study also suggests that the former can advantageously complement the later in opinion prediction

El vínculo entre la producción y la percepción y la teoría lingüística

Recent trends in infant (and adult) speech perception studies, especially in the psychological literature where much of the speech perception work is being and has been done, shows a growing focus on more integrated perception-production-sensorimotor (PPS) bases for perception (Werker &amp; Gervain 2013). We look here at whether the results of such studies are significant for theoretical linguistics – specifically for the fundamental question of how the linguistic system is acquired. We examine a selection of recent experimental results, using Bruderer, Danielson, Kandhadai &amp; Werker (2015) as the focal point.Las tendencias recientes en los estudios de percepción del habla infantil (y adulta), especialmente en la bibliografía de carácter psicológico en la que se ha enmarcado y se sigue enmarcando gran parte del trabajo sobre la percepción del habla, apuntan cada vez más hacia unas bases más integradas perceptivo-productivo-sensorimotoras (PPS) para la percepción (Werker &amp; Gervain, 2013). En este trabajo analizamos si los resultados de tales estudios son significativos para la lingüística teórica, especialmente por lo que se refiere a la interrogante fundamental acerca de cómo se adquiere el sistema lingüístico. Examinamos una selección de resultados experimentales recientes, tomando como punto de referencia el trabajo de Bruderer, Danielson, Kandhadai &amp; Werker (2015)