Adiabatic corrections for velocity-gauge simulations of electron dynamics in periodic potentials

We show how to significantly reduce the number of energy bands required to model the interaction of light with crystalline solids in the velocity gauge. We achieve this by deriving analytical corrections to the electric current density. These corrections depend only on band energies, the matrix elements of the momentum operator, and the macroscopic vector potential. Thus, the corrections can be evaluated independently from modeling the interaction with light. In addition to improving the convergence of velocity-gauge calculations, our analytical approach overcomes the long-standing problem of divergences in expressions for linear and nonlinear susceptibilities.Comment: Submitted to Computer Physics Communication

The use of Geographic Information Systems for data visualization and analysis in geography education at Swiss high schools

Geographic Information Systems (GIS) are becoming increasingly important for both professional and personal use. Not least, during the COVID-19 pandemic, they demonstrated their potential to help solve current and future problems with data analysis and visualization. In addition, smart devices, navigation applications, and social media are bringing more and more people into regular contact with GIS in their daily lives. Because of these developments, GIS has become an important part of educa- tion. While its basic concepts can be taught at lower levels, the in-depth study of GIS software and related data visualization and analysis is recommended for higher grades from high school onwards. Since it started being introduced into education, GIS has been shown to bring real-world relevance to the classroom and to be a helpful tool for promoting constructivist teaching methods. However, little is known about how GIS is used in Swiss high school classrooms. Therefore, the aim of this Thesis is to find out more about the use of GIS in Swiss secondary schools, the factors influencing its use, and the possibilities to support teachers. To this end, a survey was conducted among high school geography teachers throughout Switzerland. The results showed that about 50% of the teach- ers use GIS, and 40% let their students work with GIS software to visualize and analyze geographical information during their lessons. Based on the results from the survey, it was also found that the mention of GIS in the curriculum, the provision of GIS software by a school, and geography being a teacher’s first subject are external factors influencing the use of GIS. A teacher’s age, teaching experience, and the inclusion of GIS in a teacher’s studies do not play a major role. Furthermore, a teacher’s knowledge of GIS and how to use it in the classroom, the importance attributed to GIS, and the perceived availability of teaching materials, are internal factors influencing its use. The perceived availability of time, and the importance attached to data visualization and analysis and to GIS as a useful tool for this, do not seem to influence the use of GIS. It also emerged that teachers are most interested in support in the form of additional teaching mate- rial that is time-efficient, linked to other curriculum topics, covers different levels of difficulty, and comes with clear instructions and data. Therefore, a teaching unit has been developed in response to these needs

Inclement

Inclement, by Susan Wismer, is from Hageography: Hagios, a Greek word for holy. Hag, an old woman. Hag, an overhang at the edge of a cliff Rough notes. Foot notes. Choreographies of happenstance

Categorical Change: Exploring the Effects of Concept Drift in Human Perceptual Category Learning

Categorization is an essential survival skill that we engage in daily. A multitude of behavioral and neuropsychological evidence support the existence of multiple learning systems involved in category learning. COmpetition between Verbal and Implicit Systems (COVIS) theory provides a neuropsychological basis for the existence of an explicit and implicit learning system involved in the learning of category rules. COVIS provides a convincing account of asymptotic performance in human category learning. However, COVIS – and virtually all current theories of category learning – focus solely on categories and decision environments that remain stationary over time. However, our environment is dynamic, and we often need to adapt our decision making to account for environmental or categorical changes. Machine learning addresses this significant challenge through what is termed concept drift. Concept drift occurs any time a data distribution changes over time. This dissertation draws from two key characteristics of concept drift in machine learning known to impact the performance of learning models, and in-so-doing provides the first systematic exploration of concept drift (i.e., categorical change) in human perceptual category learning. Four experiments, each including one key change parameter (category base-rates, payoffs, or category structure [RB/II]), investigated the effect of rate of change (abrupt, gradual) and awareness of change (foretold or not) on decision criterion adaptation. Critically, Experiments 3 and 4 evaluated differences in categorical adaptation within explicit and implicit category learning tasks to determine if rate and awareness of change moderated any learning system differences. The results of these experiments inform current category learning theory and provide information for machine learning models of decision support in non-stationary environments

Optimizing Hospital Capacity to Deal with Hallway Medicine

A model adapted from Hillier and Liebermann, 2017 that optimizes hospital capacity to deal with hallway medicine

Ultrafast coherent electron dynamics in solids

Due to recent developments in high-field laser systems, intense sub-cycle pulses can be generated on a routine basis in laser laboratories around the world. The electric fields originating from such few-femtosecond laser pulses can be on the same order of magnitude as the internal electric fields in bulk, crystalline solids. Due to the short duration of the pulses the laser fluence can remain below the damage threshold of the material. This paves the way for exploring strong-field effects in solids in a non-destructive regime experimentally, and hence motivates theoretical investigations in this field. This thesis is about numerical studies of strong-field effects in insulators and semiconductors. In particular, calculations are performed at a quantum mechanical level in order to examine the importance of quantum coherence in light-matter interactions in the strong-field regime. The dynamics of electrons in one-dimensional spatially periodic potentials excited by laser pulses was simulated. Upon introducing phenomenological decoherence into the dynamical equations, it was found that the optical responses calculated from geometric phases of mixed quantum system were in excellent agreement with conventional approaches for evaluating the optically induced current and polarization response. The excellent agreement even extended to highly non-linear, strong-field regimes, and motivated the development of a numerical method to simulate open quantum mechanical systems governed by spatially periodic Hamiltonians subject to perturbations with broken translation symmetry. Density functional theory was also employed to obtain wave functions from first principles for a number of materials, for which time-resolved optical responses were calculated. Field-induced intraband motion was found to modify the interband transitions significantly at high field strengths for transitions that would otherwise be resonant at low field strengths. For semiconducting materials like GaAs, where the transition elements are strongly peaked at the centre of the Brillouin zone, a step-like excitation mechanism was revealed at field strengths on the order of 0.5 V/Å. Similar ab initio methods were used to model the optical Faraday effect in the insulating, wide band gap material Al2O3 for few-cycle pulses. The magnitude of the effect was predicted using non-perturbative methods. Time-dependent calculations confirmed that a near-instantaneous response is to be expected.Es wurde die Dynamik von Elektronen in Festkörpern, die durch intensive, Subzykluslaserpulse erregt werden numerisch untersucht. Die Berechnungen wurden auf der quantenmechanischen Ebene und in verschiedenen, unabhängigen elektromagnetischen Eichungen ausgeführt. Zuerst wurde die Dynamik der Elektronen in eindimensionalen periodischen Potentialen berechnet um die Gültigket von neuen numerischen Verfahren zu bestätigen. Eines dieser Verfahren ermöglicht Simulationen von räumlich periodischen, gemischten Quantensystemen mit Hamilton-Operatoren mit gebrochener Translationssymmetrie. Durch Anwendung der Dichtefunktionaltheorie wurden Wellenfunktionen für Halbleiter und Insulatoren hergeleitet. Danach konnt der zeitliche Verlauf des optisch induzierten Strom nach ersten Prinzipien bestimmt werden. Die Bedeutung von intraband Bewegungen für Elektronen im halbleitenden Material GaAs wurde ebenfalls untersucht. Bei Erregung mit resonanten Pulsen konnte ein stufenförmiger Anregungsmechanismus beobachtet werden. Ähnliche Methoden wurden verwendet, um die Größe des optischen Faraday-Effektes in einem Insulator mit einer Bandlücke, grösser der Fotonenergie beider Pulse, zu bestimmen. Diese Berechnungen deuten darauf hin, dass ultraschnelle Kontrolle der optisch induzierten Chiralität möglich ist

British American football: National identity, cultural specificity and globalization

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis explores the hybridity and distinctiveness of British American football. Sports have socio-historical links to specific nation-states, thus encoding them with culturally specific values. Despite a movement towards cultural convergence, especially of popular culture, aspects of sport have remained resistant to dominant globalization trends. My thesis reveals that the globalization of American football to Britain has been a process which makes concessions to the local, while still retaining many of its global characteristics. Through an ethnographic study of one team, I spent an entire season becoming an „insider‟ and understanding the British American football culture from the perspective of the participants themselves. Analysis of data collected through participant observation and interviews revealed a number of themes which defined British American football as a hybrid and distinctive sport. First, that British American football was distinctive within the domestic British sports space because of its unique combination of American characteristics. Second, that „glocalization‟ influences the structuring of British American football under the amateur code, in order for the sport to better fit within the British sporting habitus. Finally, that the two branches of American football in Britain, the NFL and the British grassroots, were found to be involved in a disparate relationship which involved each branch concentrating on their own separate agendas for the sport. In conclusion, the American football played in Britain is British American football and this study importantly demonstrates that while a sport can retain its roots in terms of its physical appearance and playing structure, in order for it to infiltrate a foreign sports space, concessions must be made to the local sporting culture. The single most important thread that ran throughout this thesis was that American football could, and has, taken on multiple meanings, which were dependent upon the national context in which it was being played. It emphasizes the idea of globalization as glocalization; that the local is important in the global aspirations of the sport of American football. British American football has placed a uniquely British stamp on an otherwise purely American pastime