An Adaptive, Kink-Based Approach to Path Integral Calculations

A kink-based expression for the canonical partition function is developed using Feynman's path integral formulation of quantum mechanics and a discrete basis set. The approach is exact for a complete set of states. The method is tested on the 3x3 Hubbard model and overcomes the sign problem seen in traditional path integral studies of fermion systems. Kinks correspond to transitions between different N-electron states, much in the same manner as occurs in configuration interaction calculations in standard ab initio methods. The different N-electron states are updated, based on which states occur frequently during a Monte Carlo simulation, giving better estimates of the true eigenstates of the Hamiltonian.Comment: 24 pages, to be published in J. Chem. Phy

Reproductive Individualism And Divorce: An Examination Of Attitudes And Marriage Dissolution In Canada

In documenting the dramatic increase in divorce in recent decades, several observers have uncovered strong empirical associations between religiosity and marriage dissolution. As well, many studies show a substantial relationship between premarital cohabitation and the risk of divorce.;What is it about religiosity and cohabitation that explains these statistical links to divorce? The main objective of this inquiry was to answer this question by placing marriage dissolution within a sociological framework. Building on concepts and ideas developed in the sociological theory of Anthony Giddens, it was argued that the recent proliferation of expert systems of knowledge and technology in the area of human reproduction has rapidly altered the social context and motivations for childbearing and childrearing.;Specifically, the thesis developed the idea that reproductive individualism has emerged as an important motivational and normative basis of marriage and family formation in modern society. Moreover, the theory developed in the study identifies reproductive individualism as a variable that might account for the documented associations among religiosity, cohabitation and divorce.;Using data from the 1984 Canadian Fertility Survey, a single factor analytic scale measuring reproductive individualism was constructed. A series of hazard models of divorce were subsequently developed to investigate the issues raised by the thesis. The results of the inquiry show that reproductive individualism is a major predictor of the risk of marriage dissolution. Additionally, reproductive individualism entirely explains the relationship between premarital cohabitation and divorce. Finally, reproductive individualist attitudes account for much of the statistical relationship between religiosity and divorce.;The general conclusion of the inquiry is that theoretically-grounded concepts such as reproductive individualism are essential to understanding contemporary trends in social demography. However, the sociological relevance of reproductive individualism may extend well beyond recent changes in marriage and the family. Indeed, the theory developed in the thesis implies that reproductive individualism has great potential to legitimize the commodification of human life by new reproductive technologies

The Role of Sustainable Local Food Among Tourism Stakeholders: A Comparative study in Vancouver, Canada and Christchurch, New Zealand

Local food is increasingly regarded as an element of sustainable tourism and hospitality. This study examines restaurant and chefs’ (tourism stakeholders) perceptions, motivations, and constraints in buying local food ingredients from local farmers’ market vendors on a study conducted in Vancouver, Canada and Christchurch, New Zealand. Semi-structured interviews were conducted with restaurants and chefs. The study identified that restaurants and chefs are most interested in perceived tangible benefit such as freshness, as well as more intangible motivations such as supporting local farmers and the local economy/community/businesses. However, they experienced challenges with purchasing. Based on the findings, strategies are posited for both restaurants and chefs and farmers (hereby farmers’ market vendors) to better serve foodservice establishments

Energy from waste and the food processing industry

The provision of a secure, continuous energy supply is becoming an issue for all sectors of society and the foodprocessingindustry as a major energy user must address these issues. This paper identifies anaerobic digestion as an opportunity to go some way to achieving energy security in a sustainable manner. However, a number of energy management and waste reduction concepts must also be brought into play if the environmental, social and economic aspects of sustainability are to be balanced. The reporting of such activity will help to promote the green credentials of the industry. Cleaner production, supply chain and life cycle assessment approaches all have a part to play as tools supporting a new vision for integrated energy and waste management. Our reliance on high-energyprocessing, such as canning and freezing/chill storage, might also need re-assessment together with processing based on hurdle technology. Finally, the concepts of energy and power management for a distributed energy generation system must be brought into the foodprocessingindustry

Tau Signals of R-parity breaking at LEP 200

The detectability at LEP 200 of explicit $R$-parity breaking by tau-number $(L_\tau)$ violating operators is considered. The assumption of $L_\tau$-violation is motivated by the relative lack of constraints on such couplings but similar considerations apply to explicit $L_e$- or $L_\mu$-violation. The $LSP$, now unstable, and not necessarily neutral, decays via $L_\tau$-violating modes. Only signals from the production and decays of $LSP$ pairs are considered, thereby avoiding any dependence on the sparticle mass spectrum. Rather spectacular signals are predicted: spherical events with $m$ leptons (usually containing at least one $\tau$) and $n$ jets $(m,n \leq 4)$, the most characteristic of which are like-sign $\tau\tau$ events. These signals are enumerated for each $LSP$ candidate and quantitative estimates are provided for the favoured case when the $LSP$ is a neutralino. Other new physics signals, which can mimic these signatures, are also briefly discussed.Comment: 27 pages in PHYZZX, six figures (not included, available on request). TIFR/TH/92-29,UH-511-751-92,CERN-TH.6613/9

New Constraints On Lepton Nonconserving R-parity Violating Couplings

Strong upper bounds are derived on certain product combinations of lepton nonconserving couplings in the minimal supersymmetric standard model with explicit $R$-parity violation. The input is information from rare leptonic decays of the long-lived neutral kaon, the muon and the tau as well as from the mixings of neutral $K$- and $B$-mesons. One of these bounds is comparable and another superior to corresponding ones obtained recently from neutrinoless double beta decay.Comment: 10 pages, LaTeX, uses style files fullpage.sty and subeqn.sty (included

The Journey to R4D: An institutional history of an Australian Initiative on Food Security in Africa

Internal Revie

Growth of epitaxially oriented Ag nanoislands on air-oxidized Si(111)-(7x7) surfaces: Influence of short range order on the substrate

Clean Si(111)-(7{x7) surfaces, followed by air-exposure, have been investigated by reflection high energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). Fourier transforms (FTs) of STM images show the presence of short range (7x7) order on the air-oxidized surface. Comparison with FTs of STM images from a clean Si(111)-(7x7) surface shows that only the 1/7th order spots are present on the air-oxidized surface. The oxide layer is ~ 2-3 nm thick, as revealed by cross-sectional transmission electron microscopy (XTEM). Growth of Ag islands on these air-oxidized Si(111)-(7x7) surfaces has been investigated by in-situ RHEED and STM and ex-situ XTEM and scanning electron microscopy. Ag deposition at room temperature leads to the growth of randomly oriented Ag islands while preferred orientation evolves when Ag is deposited at higher substrate temperatures. For deposition at 550{\deg}C face centered cubic Ag nanoislands grow with a predominant epitaxial orientation [1 -1 0]Ag || [1 -1 0]Si, (111)Ag || (111)Si along with its twin [-1 1 0]Ag || [1 -1 0]Si, (111)Ag || (111)Si, as observed for epitaxial growth of Ag on Si(111) surfaces. The twins are thus rotated by a 180{\deg} rotation of the Ag unit cell about the Si [111] axis. It is intriguing that Ag nanoislands follow an epitaxial relationship with the Si(111) substrate in spite of the presence of a 2-3 nm thick oxide layer between Ag and Si. Apparently the short range order on the oxide surface influences the crystallographic orientation of the Ag nanoislands.Comment: 10 figure