Renewal of the GSP: An Explanation of the Program and Changes Made by the 1984 Legislation

This Note outlines the purpose, scope and operation of the GSP from 1976 until 1984. Both the initial authorizing legislation and the 1984 Trade Act are analyzed. The 1979 modifications made in the Trade Agreement Act are briefly discussed where they are relevant. The 1984 Trade Act changes are detailed, with commentary on the manner in which the renewed GSP differs materially from prior law, and with discussion of the underlying policies and significance of the changes. The Note concludes with comments on the diverse objectives of the United States GSP scheme, its evolving nature, and prospects for continuation of the scheme beyond 1993

Multiple Histogram Method for Quantum Monte Carlo

An extension to the multiple-histogram method (sometimes referred to as the Ferrenberg-Swendsen method) for use in quantum Monte Carlo simulations is presented. This method is shown to work well for the 2D repulsive Hubbard model, allowing measurements to be taken over a continuous region of parameters. The method also reduces the error bars over the range of parameter values due the overlapping of multiple histograms. A continuous sweep of parameters and reduced error bars allow one to make more difficult measurements, such as Maxwell constructions used to study phase separation. Possibilities also exist for this method to be used for other quantum systems.Comment: 4 pages, 5 figures, RevTeX, submitted to Phys. Rev. B Rapid Com

Loop algorithms for quantum simulations of fermion models on lattices

Two cluster algorithms, based on constructing and flipping loops, are presented for worldline quantum Monte Carlo simulations of fermions and are tested on the one-dimensional repulsive Hubbard model. We call these algorithms the loop-flip and loop-exchange algorithms. For these two algorithms and the standard worldline algorithm, we calculated the autocorrelation times for various physical quantities and found that the ordinary worldline algorithm, which uses only local moves, suffers from very long correlation times that makes not only the estimate of the error difficult but also the estimate of the average values themselves difficult. These difficulties are especially severe in the low-temperature, large-$U$ regime. In contrast, we find that new algorithms, when used alone or in combinations with themselves and the standard algorithm, can have significantly smaller autocorrelation times, in some cases being smaller by three orders of magnitude. The new algorithms, which use non-local moves, are discussed from the point of view of a general prescription for developing cluster algorithms. The loop-flip algorithm is also shown to be ergodic and to belong to the grand canonical ensemble. Extensions to other models and higher dimensions is briefly discussed.Comment: 36 pages, RevTex ver.

Traces of the (m)other: deconstructing hegemonic historical narrative in Teat(r)o Oficina Uzyna Uzona's Os Sertões

This article focuses on the way in which renowned São Paulo-based theatre company Teat(r)o Oficina Uzyna Uzona deconstructs hegemonic historical narrative in their 2000 - 2007 25 hour-long production of Euclides da Cunha’s seminal Brazilian novel Os sertões (“Rebellion in the Backlands”), an account of the War of Canudos (1896-1897), the first major act of State terrorism carried out by the nascent Brazilian Federal Government on the country’s subaltern population. The Teat(r)o Oficina’s epic adaptation fuses events from the colonial period, the military dictatorship and contemporary 21st Century São Paulo to relate the repetitive cycles of misappropriation, oppression and resistance that have characterized the history of Brazil and its people over the centuries. However, any fatalistic view of victimhood as an essential aspect of Brazilian subjectivity is radically challenged by the vibrant, rhythmic, material impact of the theatrical super-signs underpinning the performance text. Drawing on Julia Kristeva’s notion of the semiotic - the pre-linguistic, illogical, rhythmical materialism of language intimately related to a primordial relationship with the abject mother – I shall suggest that it is the rhythmic, libidinal force of the performance and its extensive use of the cultural manifestations of Brazil’s subaltern population that imbues Os Sertões with the silent presence-as-absence of the abject Brazilian (M)Other – the Black, Indigenous and Mestiza matriarchal line whose alternative discourse is often barred from hegemonic accounts of Brazilian historiography. Her silent heritage is embodied on stage by the members of the Oficina, who reclaim an alienating national heritage for themselves by transforming the often tragic tale of Brazil’s past into a joyous celebration of tenacious vitality

Pairing Correlations in the Two-Dimensional Hubbard Model

We present the results of a quantum Monte Carlo study of the extended $s$ and the $d_{x^2-y^2}$ pairing correlation functions for the two-dimensional Hubbard model, computed with the constrained-path method. For small lattice sizes and weak interactions, we find that the $d_{x^2-y^2}$ pairing correlations are stronger than the extended $s$ pairing correlations and are positive when the pair separation exceeds several lattice constants. As the system size or the interaction strength increases, the magnitude of the long-range part of both correlation functions vanishes.Comment: 4 pages, RevTex, 4 figures included; submitted to Phys. Rev. Let

A Constrained Path Quantum Monte Carlo Method for Fermion Ground States

We propose a new quantum Monte Carlo algorithm to compute fermion ground-state properties. The ground state is projected from an initial wavefunction by a branching random walk in an over-complete basis space of Slater determinants. By constraining the determinants according to a trial wavefunction $|\Psi_T \rangle$, we remove the exponential decay of signal-to-noise ratio characteristic of the sign problem. The method is variational and is exact if $|\Psi_T\rangle$ is exact. We report results on the two-dimensional Hubbard model up to size $16\times 16$, for various electron fillings and interaction strengths.Comment: uuencoded compressed postscript file. 5 pages with 1 figure. accepted by PRL

Nuclear Magnetic Resonance and Hyperfine Structure

Contains reports on seven research projects

Chemoprevention of lung cancer—from biology to clinical reality

Lung cancer is the commonest cause of cancer death in developed countries and throughout the world. Cigarette smoking is the main risk factor for lung cancer and ex-smokers today comprise ∼50% of all new lung cancer cases. Chemoprevention builds on the concepts of field of cancerization and multistep carcinogenesis and can be defined as the use of natural or chemical compounds to prevent, inhibit or reverse the process of carcinogenesis. So far, chemoprevention studies in lung cancer have failed to reduce lung cancer mortality. New developments in biotechnology have made it possible to define more accurately high-risk populations, make earlier diagnosis possible, and allow more specific targeted therapies to be developed. Both the development and validation of biomarkers, for the selection of high-risk study populations and for response evaluation in chemoprevention studies, are important for the faster turnover of studies evaluating new agents. This article reviews the current status and describes the perspectives for new approaches in the chemoprevention of lung cance