Crossover from Diffusive to Ballistic Transport in Periodic Quantum Maps

We derive an expression for the mean square displacement of a particle whose motion is governed by a uniform, periodic, quantum multi-baker map. The expression is a function of both time, $t$, and Planck's constant, $\hbar$, and allows a study of both the long time, $t\to\infty$, and semi-classical, $\hbar\to 0$, limits taken in either order. We evaluate the expression using random matrix theory as well as numerically, and observe good agreement between both sets of results. The long time limit shows that particle transport is generically ballistic, for any fixed value of Planck's constant. However, for fixed times, the semi-classical limit leads to diffusion. The mean square displacement for non-zero Planck's constant, and finite time, exhibits a crossover from diffusive to ballistic motion, with crossover time on the order of the inverse of Planck's constant. We argue, that these results are generic for a large class of 1D quantum random walks, similar to the quantum multi-baker, and that a sufficient condition for diffusion in the semi-classical limit is classically chaotic dynamics in each cell. Some connections between our work and the other literature on quantum random walks are discussed. These walks are of some interest in the theory of quantum computation.Comment: Final version to appear in Physica D, Proceedings of the International Workshop and Seminar on Microscopic Chaos and Transport in Many-Particle Systems, Dresden, 2002; corrected a minor error in section 3.1, new section 4.

The measurement of driver describing functions in simulated steering control tasks

Measurements of driver describing functions in steering control tasks have been made using a driving simulator. The task was to regulate against a random crosswind gust input on a straight roadway, in order to stay in the center of the lane. Although driving is a multiloop task in general, the forcing function and situation were configured so that an inner-loop visual cue feedback of heading angle of heading rate would dominate, and the driver's response was interpreted to be primarily single-loop. The driver describing functions were measured using an STI describing function analyzer. Three replications for each subject showed good repeatability within a subject. There were some intersubject differences as expected, but the crossover frequencies, effective time delays, and stability margins were generally consistent with the prior data and models for similar manual control tasks. The results further confirm the feasibility of measuring human operator response properties in nominal control tasks with full (real-world) visual field displays

The Exercise of Criminal Justice in Medieval Towns: A Comparison of English and Polish Jurisdiction

The thesis offers a new vision of medieval criminal justice and for the first time identifies the significant common elements in the exercise of criminal law regulations in selected fourteenth-century towns in two contrasting countries in late medieval Europe, England and Poland. These elements include principles of cooperation and control between royal and local powers in the establishment and exercise of legal proceedings. These are also among the main determinants of the developing status and agency of medieval European urban communities including their executive powers. Through a comparative analysis of the local practice that comprised criminal justice in both nations’ systems of law, this thesis marks new ground in the study of international features of criminal law proceedings in the period. It also contributes to a wider understanding of local mechanisms of control and the extent to which towns nevertheless relied upon the enforcement power of central royal authorities. Focusing on towns like Bristol, Exeter, Norwich, York, Wrocław and Kraków, this study explores the importance of local legal regulation in each town’s development, their aspirations to control their own administrative and legal processes and the limits to their level of autonomy. The thesis examines the individual stages of how local criminal law was exercised in towns of both countries, by demonstrating from various legal documents that formed parts of royal grants, privileges and charters, the roles of executive bodies directly involved in implementing local laws. The results reveal that despite political, territorial and monarchical differences that existed between the countries and their separate systems of law, there were certain common elements that arguably provide an international character for the application of local criminal justice. The thesis expands upon existing knowledge and scholarship about the essential role of corporal punishments in municipal legal proceedings, including how these were appropriate to each criminal and their specific crime. It also identifies a new approach towards the main factors affecting the active pursuit of criminal justice in England and Poland, especially their impact upon a general understanding of medieval European law enforcement procedures

Subjective experience of episodic memory and metacognition: a neurodevelopmental approach.

Episodic retrieval is characterized by the subjective experience of remembering. This experience enables the co-ordination of memory retrieval processes and can be acted on metacognitively. In successful retrieval, the feeling of remembering may be accompanied by recall of important contextual information. On the other hand, when people fail (or struggle) to retrieve information, other feelings, thoughts, and information may come to mind. In this review, we examine the subjective and metacognitive basis of episodic memory function from a neurodevelopmental perspective, looking at recollection paradigms (such as source memory, and the report of recollective experience) and metacognitive paradigms such as the feeling of knowing). We start by considering healthy development, and provide a brief review of the development of episodic memory, with a particular focus on the ability of children to report first-person experiences of remembering. We then consider neurodevelopmental disorders (NDDs) such as amnesia acquired in infancy, autism, Williams syndrome, Down syndrome, or 22q11.2 deletion syndrome. This review shows that different episodic processes develop at different rates, and that across a broad set of different NDDs there are various types of episodic memory impairment, each with possibly a different character. This literature is in agreement with the idea that episodic memory is a multifaceted process