Uncertainty and the politics of employment protection

This paper investigates the social preferences over labor market exibility, in a general equilibrium model of dynamic labor demand. We demonstrate that how the economy responds to productivity shocks depends on the power of labor to extract rents and on the status quo level of the firing cost. In particular, we show that when the firing cost is initially relatively low, a transition to a rigid labor market is favored by all the employed workers with idiosyncratic productivity below some threshold value. Conversely, when the status quo level of the firing cost is relatively high, the preservation of a rigid labor market is favored by the employed with intermediate productivity, whereas all other workers favor more exibility. A more volatile environment, and a lower rate of productivity growth, i.e., "bad times," increase the political support for more labor market rigidity only where labor appropriates of relatively large rents. The coming of better economic conditions not necessarily favors the demise of high firing costs in rigid high-rents economies, because "good times" cut down the support for flexibility among the least productive employed workers. The model described provides some new insights on the comparative dynamics of labor market institutions in the U.S. and in Europe over the last few decades, shedding some new light both on the reasons for the original build-up of "Eurosclerosis," and for its relative persistence until the present day

Learning in Goal Oriented Autonomous Systems

This report, prepared for the Computer Science Laboratory at SRI International, covers the development of a Learning component for PAGODA, a modular architecture for goal directed agents that explore an environment without need for constant commands from an operator. Two learning algorithms are presented and our algorithm implementations analyzed. The report highlights the changes made to PAGODA and the development challenges encountered. Additionally, several potential improvements to the PAGODA system are given

An investigation into the interaction between potential building clients and construction professionals

This research investigates the interaction process between building clients and construction professionals. The context of the interaction is the first meeting between the parties to discuss a potential construction project. The objective of the research was to determine whether clients, with differing levels of construction experience, and construction professionals, from different disciplines (architects, quantity surveyors, consulting engineers and contractors), exhibit distinctive interaction characteristics, both in terms of how they interact and the subject matter of their interactions. In order to test a number of hypotheses about the interactions an experimental procedure was developed. This involved arranging a series of interviews between the different client types and the construction professionals. 44 interviews were conducted with each one being recorded and then transcribed. Additional data was collected in the form of participant questionnaires and personality tests. Transcripts were coded using systems developed for this investigation, using measures of nature of interaction and subject matter. Processing and analysis of the data was conducted using ethnographic computer software and programs written specifically for this research project. A database was created from the interview data which allows selective retrieval of segments of interviews. The database comprises of approximately 215,000 words, with 58,000 codes assigned to text segments. The results of the analysis are presented in both quantitative and qualitative forms, and show that there are significant differences in the interactions. In interviews between inexperienced clients and professionals the professionals make the greater contributions, dominating the clients. There is a reversal of the roles when experienced clients interact with professionals, with the clients assuming the dominant position. In addition the results show that in interviews between inexperienced clients and professionals, the four professional disciplines emphasis different factors. All professionals raise issues relating to primary factors such as time, cost and quality. However, the discussion of other building factors was more specific to a particular professional discipline. Finally, the research also concluded that the element of personality differences in interviews was an influential factor in determining whether their outcome was perceived as successful by the participants

An act relating to authorizing the dissolution of the Bexar Metropolitan Water District; providing a penalty.

Bill introduced by the Texas Senate relating to authorizing the dissolution of the Bexar Metropolitan Water District; providing a penalty

Exotic Ground States and Dynamics in Constrained Systems

The overarching theme of this thesis is the question of how constraints influence collective behavior. Constraints are crucial in shaping both static and dynamic properties of systems across diverse areas within condensed matter physics and beyond. For example, the simple geometric constraint that hard particles cannot overlap at high density leads to slow dynamics and jamming in glass formers. Constraints also arise effectively at low temperature as a consequence of strong competing interactions in magnetic materials, where they give rise to emergent gauge theories and unconventional magnetic order. Enforcing constraints artificially in turn can be used to protect otherwise fragile quantum information from external noise. This thesis in particular contains progress on the realization of different unconventional phases of matter in constrained systems. The presentation of individual results is organized by the stage of realization of the respective phase. Novel physical phenomena after conceptualization are often exemplified in simple, heuristic models bearing little resemblance of actual matter, but which are interesting enough to motivate efforts with the final goal of realizing them in some way in the lab. One form of progress is then to devise refined models, which retain a degree of simplification while still realizing the same physics and improving the degree of realism in some direction. Finally, direct efforts in realizing either the original models or some refined version in experiment today are mostly two-fold. One route, having grown in importance rapidly during the last two decades, is via the engineering of artificial systems realizing suitable models. The other, more conventional way is to search for realizations of novel phases in materials. The thesis is divided into three parts, where Part I is devoted to the study of two simple models, while artificial systems and real materials are the subject of Part II and Part III respectively. Below, the content of each part is summarized in more detail. After a general introduction to entropic ordering and slow dynamics we present a family of models devised as a lattice analog of hard spheres. These are often studied to explore whether low-dimensional analogues of mean-field glass- and jamming transitions exist, but also serve as the canonical model systems for slow dynamics in granular materials more generally. Arguably the models in this family do not offer a close resemblance of actual granular materials. However, by studying their behavior far from equilibrium, we observe the onset of slow dynamics and a kinetic arrest for which, importantly, we obtain an essentially complete analytical and numerical understanding. Particularly interesting is the fact that this understanding hinges on the (in-)ability to anneal topological defects in the presence of a hardcore constraints, which resonates with some previous proposals for an understanding of the glass transition. As another example of anomalous dynamics arising in a magnetic system, we also present a detailed study of a two-dimensional fracton spin liquid. The model is an Ising system with an energy function designed to give rise to an emergent higher-rank gauge theory at low energy. We show explicitly that the number of zero-energy states in the model scales exponentially with the system size, establishing a finite residual entropy. A purpose-built cluster Monte-Carlo algorithm makes it possible to study the behavior of the model as a function of temperature. We show evidence for a first order transition from a high-temperature paramagnet to a low-temperature phase where correlations match predictions of a higher-rank coulomb phase. Turning away from heuristic models, the second part of the thesis begins with an introduction to quantum error correction, a scheme where constraints are artificially imposed in a quantum system through measurement and feedback. This is done in order to preserve quantum information in the presence of external noise, and is widely believed to be necessary in order to one day harness the full power of quantum computers. Given a certain error-correcting code as well as a noise model, a particularly interesting quantity is the threshold of the code, that is the critical amount of external noise below which quantum error correction becomes possible. For the toric code under independent bit- and phase-flip noise for example, the threshold is well known to map to the paramagnet to ferromagnet transition of the two-dimensional random-bond Ising model along the Nishimori line. Here, we present the first generalization of this mapping to a family of codes with finite rate, that is a family where the number of encoded logical qubits grows linearly with the number of physical qubits. In particular, we show that the threshold of hyperbolic surface codes maps to a paramagnet to ferromagnet transition in what we call the 'dual'' random-bond Ising model on regular tessellations of compact hyperbolic manifolds. This model is related to the usual random-bond Ising model by the Kramers-Wannier duality but distinct from it even on self-dual tessellations. As a corollary, we clarify long-standing issues regarding self-duality of the Ising model in hyperbolic space. The final part of the thesis is devoted to the study of material candidates of quantum spin ice, a three-dimensional quantum spin liquid. The work presented here was done in close collaboration with experiment and focuses on a particular family of materials called dipolar-octupolar pyrochlores. This family of materials is particularly interesting because they might realize novel exotic quantum states such as octupolar spin liquids, while at the same time being described by a relatively simple model Hamiltonian. This thesis contains a detailed study of ground state selection in dipolar-octupolar pyrochlore magnets and its signatures as observable in neutron scattering. First, we present evidence that the two compounds Ce2Zr2O7 and Ce2Sn2O7 despite their similar chemical composition realize an exotic quantum spin liquid state and an ordered state respectively. Then, we also study the ground-state selection in dipolar-octupolar pyrochlores in a magnetic field. Most importantly, we show that the well-known effective one-dimensional physics -- arising when the field is applied along a certain crystallographic axis -- is expected to be stable at experimentally relevant temperatures. Finally, we make predictions for neutron scattering in the large-field phase and compare these to measurements on Ce2Zr2O7

Investigating generalized Kitaev magnets using machine learning

Frustration in Kitaev-Materialien führt zu einem sehr reichhaltigen und komplexen Phasendiagramm, einschließlich der klassischen Spinflüssigkeitsphase. Die Suche nach und das Verständnis von Spinflüssigkeiten und weiteren neuartigen komplexen Phasen der Materie stehen im Mittelpunkt der heutigen Forschung zu kondensierter Materie. Mittels analytischer Methoden Ordnungsparameter zur Charakterisierung dieser Phasen zu finden, ist nahezu unmöglich. Bei niedrigen Temperaturen ordnen sich die meisten klassischen Spinsysteme in komplizierte Strukturen, die große magnetische Elementarzellen belegen, was die Komplexität des Problems noch weiter erhöht und außerhalb des Anwendungsbereichs der meisten herkömmlichen Methoden liegt. In dieser Arbeit untersuchen wir die Hamilton-Operatoren realitätsnaher Kitaev-Materialien mithilfe maschinellen Lernens. Hauptmerkmale des zugrundeliegenden Algorithmus sind unbeaufsichtigtes Lernen, welches ermöglicht die Topologie eines Phasendiagramms ohne jegliche Vorkenntnisse erforschen, und Interpretierbarkeit, welche zur Analyse der Struktur der klassischen Grundzustände notwendig ist. In den ersten drei Kapiteln werden wir den Algorithmus des maschinellen Lernens auf verschiedene Hamilton-Operatoren anwenden, die zur Modellierung von Kitaev-Materialien eingesetzt werden, um zu untersuchen inwieweit die Quantenmodelle und die experimentellen Beobachtungen allein durch deren klassischen Grenzfall erklärt werden können. Darüber hinaus erforschen wir weitere Features dieses Algorithmus, die es uns ermöglichen, verborgene Symmetrien, lokale Einschränkungen der klassischen Spinflüssigkeiten, sowie bisher unbekannte Phasen im hochdimensionalen Phasenraum aufzudecken. In den letzten beiden Kapiteln werden wir uns mit dem Verständnis der Struktur der klassischen Grundzustände befassen, welche durch die Verflechtung mehrerer Helices charakterisiert sind. Wir werden auch versuchen, die Signatur dieser Phasen in Experimenten zu verstehen, indem wir die Dynamik und den Transport durch Kitaev-Magnete untersuchen. Diese Arbeit beweist die Tauglichkeit von maschinellem Lernen, hochkomplexe Phasendiagramme mit wenig bis gar keinem Vorwissen aufzudecken und hochfrustrierten Magnetismus zu erforschen. Die Kombination aus maschinellem und menschlichem Einsatz ebnet den Weg zu neuen und spannenden physikalischen Erkenntnissen.Bond frustration in Kitaev materials leads to a very rich phase diagram with highly intricate phases including the classical spin liquid phase. The search and understanding of spin liquids and novel complex phases of matter is at the heart pf present day condensed matter research. To search and design order parameters to characterize these phases using analytical approaches is a nearly impossible task. At low temperatures, most of the classical spins order into complicated spin structures occupying large magnetic unit cells which further adds to the complication and is out of the realm of most traditional methods. In this thesis we investigate realistic Kitaev material Hamiltonians using a machine learning framework whose key features, of unsupervised learning which helps us study the topology of the phase diagram without prior knowledge and interpretability which helps us analyse the structure of the classical ground states, are exploited. In the first three chapters, we shall use this framework on different Hamiltonians used to model Kitaev materials and understand to what extent the quantum limit and experimental results could be explained just by the classical limit of these models. We in addition explore other features of this framework which lets us uncover hidden symmetries as well as local constraints for the classical spin liquids and hitherto unreported new phases in the high dimensional phase space. In the last two chapters we shall dwell on the understanding the structure of the classical ground states which is quite complicated as it hosts a tangle of multiple helices. We shall also try and understand the signature of these phases on experiments by studying the dynamics and transport through Kitaev magnets thus bridging the gap between experiment and theory. This thesis proves instances of using machine learning to uncover highly complex phase diagrams with little to no previous knowledge and serve as a paradigm to explore highly frustrated magnetism. Through a combination of machine and human effort we are on the way to uncover new and exciting physics

Annual reports of Westmoreland, NH town officers for the year ending December 31, 2015 and school district officers for the year ending June 30, 2015.

This is an annual report containing vital statistics for a town/city in the state of New Hampshire

Small sugar farmer agency in the tropics 1872-1914 and the anomalous Herbert River Farmers' Association

One hundred and thirty-six years ago six immigrant small selectors formed the Herbert River Farmers’ Association (HRFA). On the Herbert a plantation mode of sugar production began in 1872. The selectors there, used the HRFA to actively participate in the transition of the tropical Australian sugar industry from plantation to small, family farms by 1914. Associations such as theirs formed the cornerstone of the institutional foundations of a globally unique and successful industry farmed by small, family farmers. Principal exponents of sugar industry organization history have consistently dismissed the small sugar cane farmers’ associations. Broader sugar industry scholarship however, identified them as having contributed to the demise of plantation production and the development of farm-based central milling. This assessment recognized that the HRFA and fellow small associations promoted small farming and that their members proved that white, small sugar farmers could farm in a tropical environment without detriment to their health and could provide a reliable supply of high-quality cane. Agricultural associations in sugar growing regions in the period 1872 to 1914 were dominated by white elite planters, practising an exploitative mode of production that used unfree or indentured coloured labour. Furthermore, land was not distributed equally to planters and small farmers alike, denying the small farmers, white or otherwise, the type of independence that came to characterise Australian white, small, sugar farmers. Land ownership and the freedom to form associations allowed the small selectors of the Herbert River Valley in tropical north Queensland in the late nineteenth century to negotiate with the planters in a way that the tenant farmers and share-croppers in other sugar growing regions could not. Accounts of the origins and nature of the sugar industry agricultural association movement focus exclusively on the planter associations while small sugar farmer associations are virtually invisible in the scholarship. Agricultural associations were vehicles both planters and farmers used to access rural extension, promote agricultural skills and innovation, and lobby with one voice. A top-down approach has made for a void in the understanding and appreciation of the development and role of small sugar industry agricultural associations in Australia. The Australian small sugar farmers’ association was unique in the global sugar industry association movement and the HRFA was the first of its kind in the plantation era in tropical Australia