Oscillator tunneling dynamics in the Rabi model

The familiar Rabi model, comprising a two-level system coupled to a quantum harmonic oscillator, continues to produce rich and surprising physics when the coupling strength becomes comparable to the individual subsystem frequencies. We construct approximate solutions for the regime in which the oscillator frequency is small compared to that of the two-level system and the coupling strength matches or exceeds the oscillator frequency. Relating our fully quantum calculation to a previous semi-classical approximation, we find that the dynamics of the oscillator can be considered to a good approximation as that of a particle tunneling in a classical double-well potential, despite the fundamentally entangled nature of the joint system. We assess the prospects for observation of oscillator tunneling in the context of nano- or micro-mechanical experiments and find that it should be possible if suitably high coupling strengths can be engineered.Comment: 25 pages, 5 figures, preprint forma

Active reservoir management: a model solution

Steady-state procedures, of their very nature, cannot deal with dynamic situations. Statistical models require extensive calibration, and predictions often have to be made for environmental conditions which are often outside the original calibration conditions. In addition, the calibration requirement makes them difficult to transfer to other lakes. To date, no computer programs have been developed which will successfully predict changes in species of algae. The obvious solution to these limitations is to apply our limnological knowledge to the problem and develop functional models, so reducing the requirement for such rigorous calibration. Reynolds has proposed a model, based on fundamental principles of algal response to environmental events, which has successfully recreated the maximum observed biomass, the timing of events and a fair simulation of the species succession in several lakes. A forerunner of this model was developed jointly with Welsh Water under contract to Messrs. Wallace Evans and Partners, for use in the Cardiff Bay Barrage study. In this paper the authors test a much developed form of this original model against a more complex data-set and, using a simple example, show how it can be applied as an aid in the choice of management strategy for the reduction of problems caused by eutrophication. Some further developments of the model are indicated

An Ethos of Sustainability: Integrated Sustainability for Urban Development

Curitiba, Brazil has become an international model for sustainable development and social regeneration. Its success has been despite a diminutive budget and rather has depended on creative, multi-dimensional solutions that solve multiple problems simultaneously. This paper analyzes Curitiba’s urban parks and public transportation policies in relation to a holistic definition of sustainable development. The purpose of this article is to highlight the manner by which Curitiba has created an ethos of sustainability so that other cities might learn to emulate this model while recognizing the ways in which many of these policies are specific to the place where they are implemented.Faculty Sponsor: Dr. Lauretta Frederkin

Intervention Research for the Education and Empowerment of Families Experiencing Homelessness: Exploring Knowledge of Tenant Rights and Perceptions of Personal Empowerment

Family homelessness emerged as a social issue in the United States in the 1980s and has since established itself as a pervasive social problem. The issue of family homelessness is complex and multifaceted with multiple social, political, and economic contributing factors. Historically, society at large has been apt to attribute homelessness to individual faults and deficits, but the fact that family homelessness has only emerged and persisted as a notable social problem in recent decades hints at political and economic mechanisms at work that serve to complicate and perpetuate the problem. Tenant eviction is one such mechanism that appears to be a major contributing factor to housing instability and episodic family homelessness. Eviction has recently come under scrutiny by sociologists, economists, and attorneys at law but has received little, if any, attention from the field of social work. As social workers are mandated by their code of ethics to aid and empower vulnerable, poor, and oppressed populations, the potential role that insufficient knowledge of tenant rights and eviction play in compounding and exacerbating family homelessness demands investigation by the social work profession. This study explores the potential of intervention with homeless families to provide information on tenant rights and responsibilities. The intervention is based in critical and empowerment theories and designed with the intention of raising critical consciousness among families experiencing homelessness. Findings from the study indicate that the intervention shows promise as a vehicle for empowering homeless families with knowledge and skills for successful tenancy. The social work field is encouraged to pursue further intervention research as a venue for empowering homeless families to effectively address their own needs

Factors associated with invasive lung aspergillosis and the significance of positive aspergillus culture after liver transplantation

From January 1981 to December 1990, 2180 patients underwent orthotopic liver transplantation at the University of Pittsburgh. Thirty-two patients (1.5%) were identified with invasive aspergillosis (29 lung, 2 intraabdominal, 1 meningitis). Of 29 patients with invasive lung disease, only 23 (79%) had positive culture (Aspergillus fumigatus, 20; Aspergillus flavus, 3). Forty-eight variables were analyzed and compared in 23 patients with invasive disease with positive cultures and 9 patients with colonization only. The variables associated with pulmonary invasive disease, by univariate analysis, were surgical time (P =.03), presence of laparotomies (P =.02), higher creatinine level at time of Aspergillus isolation (P =.01), and use of OKT3 (P =.02). However, in a multivariate analysis, only the last two (creatinine, OKT3) were associated with invasive lung aspergillosis. Of 4 patients with positive abdominal wound culture, 2 had local invasive aspergillosis. Therefore, positive cultures of Aspergillus organisms from respiratory secretions and wound drainage may represent invasive disease and should not be ignored. © 1992 the University of Chicago

ERISA Preemption: Judicial Flexibility and Statutory Rigidity

This Article attempts to describe the ways in which, and the reasons why section 514(a) has caused the courts and Congress so much difficulty. Part I reviews the legislative history of section 514(a), with emphasis on the ambivalence Congress has shown toward its 1974 draftsmanship. Part II attempts to provide a coherent description of the case law that has developed under section 514(a). Part III completes the legislative history by examining the two instances in which experience compelled Congress to revise section 514. Finally, Part IV discusses examples of problems courts have faced when crafting a federal common law of employee benefits in light of section 514 and concludes that the peculiar absence in section 514 of any recognition of state policies has had an adverse effect on the common law process. The primary shortcoming of section 514 is that, although it establishes a good starting point for thinking about ERISA preemption, it falls short both as a practical rule and as a guide to principled decisionmaking. Courts have thus had little choice but to create a federal common law of ERISA, including preemption, in spite of, and to some extent hindered by, the literal language of the statute