Nonlinear parity-time-symmetric transition in finite-size optical couplers

Parity-time-symmetric ($\mathcal{PT}$-symmetric) optical waveguide couplers offer a great potential for future applications in integrated optics. Studies of nonlinear $\mathcal{PT}$-symmetric couplers present new possibilities for ultracompact configurable all-optical signal processing. Here, we predict nonlinearly triggered transition from a full to a broken $\mathcal{PT}$-symmetric regime in finite-size systems described by smooth permittivity profiles and, in particular, in a conventional discrete waveguide directional coupler configuration with a rectangular permittivity profile. These results suggest a practical route for experimental realization of such systems

The Role of Economic Instruments to Resolve Water Quantity Problems

Resource /Energy Economics and Policy,

CONSUMER'S PERCEPTIONS OF ENVIRONMENTAL RISKS AND THE DEMAND FOR FOOD SAFETY

Public concern regarding food safety has emerged as a major policy issue. Chemicals and biotechnological processes are perceived as risks of food safety despite their contribution to an efficient, low cost agriculture and food industry. Increases in uses of biotechnological processes for foods are expected to be a major potential source of productivity improvements for Alberta and Canadian agriculture in future years. However, the demand for food safety involves increasing awareness and concern by consumers of chemical inputs and biotechnological processes in the agriculture and food industries. Nonetheless, there is a lack of basic economic and agricultural economic theory and methodology to analyze these issues and a need for policy, socioeconomics and marketing research on biotechnology and other environmental risk situations in the agricultural and food industry. This project was directed at developing and applying economic theory and methodology to help fill this gap. A major contribution of the project is the identification and verification of methodologies of stated choice to analyse tradeoffs arising from food safety perceptions of concerns by consumers. One component of the research project involved assessment of Alberta consumers' stated preferences and purchase behaviour for foods exhibiting a range of environmental risks, including perceptions of pesticide residues and hormonal treatments derived from biotechnological processes. The results of this survey indicated that Albertans were more concerned about pesticide use in food production than about the use of hormones. In contingent valuation questions developed for the study, more Albertans wish to restrict pesticide use (relative to a base case of not restricting either hormones or pesticides). They tended to persist in these choices in the face of potential increases in food costs, reflecting a higher level of concern with pesticides than hormones. Increasing education increased this concern. Increasing food cost decreased the probability of choosing to restrict pesticide or hormone use. Women appeared to perceive pesticide use in food production as a greater food safety risk than was perceived by men. The inferred average willingness to pay to restrict pesticide and growth hormone use in food production amounted to about 25% and 13% respectively of the average Albertan's food expenditures respectively. In the second survey of consumers' food/environmental risk perceptions undertaken relative to this project, the responses of a random sample of consumers to the use of recombinant bovine somatotrophin (rBST) in milk production were elicited using a stated preference methodology. A conditional logit model of consumer choice was developed and tested to analyse consumers' choices of milk with varying characteristics of fat content, price, freshness and rBST treatment. Awareness of rBST presence or otherwise is implied by labelling. The approach attempts to simulate market conditions with and without rBST labelled milk and to predict consumers' responses to variations in these conditions. Welfare calculations for a representative consumer indicate welfare losses with the introduction of rBST. These were slightly less for a male than a female household food purchaser and were less for food purchasers with higher levels of income and education. There was a small welfare gain when the representative food purchaser was offered a full range of "rBST" and "non-rBST" milks. The results suggest that making appropriately labelled "rBST-free" milk available to consumers could decrease consumer welfare losses associated with any introduction of rBST. The outcomes from application of these methodologies were related to the evidence of consumers' purchasing behaviour after licensing of the technology of rBST for use in the United States; this introduction did not require labelling. The assessment suggests a critical impact of product labelling policies and strategies on potential market impacts. An assessment is also made of Canada's food safety regulatory framework. The need for increased transparency and greater public participation in regulatory processes as means to increase public confidence in such food safety regulatory processes, specifically relating to biotechnology, is also identified.Food Consumption/Nutrition/Food Safety,

BSE and the Dynamics of Beef Consumption: Influences of Habit and Trust

This study relates habit persistence and trust to recurring food safety incidents in the context of a series of three BSE incidents in Canada. We examined the dynamics of monthly beef expenditure shares of a sample of Canadian households for monthly time periods during year 2002 through 2005 using micro level panel data which followed meat expenditures by Canadian households before and after the first three BSE cases which were discovered in 2003 and 2005. Our results suggest that households’ reactions to the first three BSE events followed a similar general pattern: households reduced beef purchase expenditures following the discovery of BSE but these expenditures subsequently recovered, suggesting that concern diminished over time. Following the first BSE event, we identified an immediate negative impact on beef expenditures. However, in the case of the second and third BSE events, this negative impact was not evident until two months after these BSE announcements. In each of the three cases, the negative impact of BSE on beef purchase expenditures was limited to no more than four months. Assessment of how habit persistence affected beef expenditures indicates that this influence limited households reductions of beef purchases following the BSE events, but the effects of habit diminished subsequent to the initial event. Regarding the role of trust in shaping households’ reactions to BSE, we found that households’ respondents whose answers to standardized questions suggest that they are not “trusting” individuals were more sensitive to the food risks identified by the BSE events.BSE, habit, and trust, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,

Consumers' Responses to the Potential Use of Bovine Somatotrophin in Canadian Dairy Production

The responses of a random sample of consumers to the use of bovine somatotrophin (BST) in milk production were elicited using a stated preference methodology. A multinomial logit model of consumer choice was developed and tested to analyse consumers' choices of milk with varying characteristics of fat content, price, freshness and BST treatment. Welfare calculations for a representative consumer indicate welfare losses with the introduction of BST which are not fully offset by preferred milk attributes such as reduced price or increased freshness levels. Welfare losses were slightly less for a male than a female consumer and were less for consumers with higher levels of income and education. Losses were greatest when a representative consumer was denied the option of choosing not to purchase milk. There was a small welfare gain when the representative consumer was offered a full range of "BST" and "non-BST" milks. The results suggest that making appropriately labelled "BST-free" milk available to consumers could decrease consumer welfare losses associated with the introduction of BST in Canada.Consumer/Household Economics, Livestock Production/Industries,

Risk Perceptions, Social Interactions and the Influence of Information on Social Attitudes to Agricultural Biotechnology

We assess Canadian’s risk perceptions for genetically modified (GM) food and probe influences of socio-economic, demographic and other factors impinging on these perceptions. An internet-administered questionnaire with two stated choice split-sample experiments that approximate market choices of individual grocery shoppers is applied to elicit purchase behavior from 882 respondents across Canada. Data are collected to assess the influence on respondents’ choices for a specific food product (bread) of 1) product information which varies in content and by source and 2) information provided through labeling. These data also enable: a) analysis of trade-offs made by consumers between possible risks associated with GM ingredients and potential health or environment benefits in food and b) assessment of influences on respondents’ search for/access of product information. We rigorously document the extent and type of variation in Canadian consumers’ attitudes and risk perceptions for a selected GM food. This is pursued in analysis of experiment 1) data using a latent class model to analyze 445 consumers’ choices for bread products. We identify four distinct groups of Canadian consumers: 51% (value seekers) valued additional health or environmental benefits and were indifferent to GM content; traditional consumers (14 %) preferred their normally-purchased food; fringe consumers (4%) valued the health attribute and could defer consumption. Another 32 % (anti-GM) strongly opposed GM ingredients in food irrespective of introduced attributes. Thus there is a dichotomy in Canadian attitudes to GM content in food: a small majority of the sample (55 per cent) perceive little or no risk from GM food, but this is strongly opposed by 46% of respondents. Differences in gender, number of children in the household, education, and age are associated with the likelihood of segment membership. We also report on the search for information on characteristics of the GM food by a sample of 445 respondents with opportunity for voluntary access to related information through hyperlinks in the survey. Slightly less than half actually sought such information. Gender, employment status, rural or urban residency and the number of children in the household all affected the probability that respondents would access information. A further research component examines product choices made in the context of two common GM labeling policies: mandatory and voluntary labeling. We find these two types of strategies to have distinctive impacts on consumers and on measures of social welfare. Knowledge of these may help policy makers to make more informed analyses of the alternative labeling policies. Specific findings also provide base-line measures of Canadians’ attitudes to risks of GM technology in the context of food and environmental risks, as well as documenting the importance of context influences and reference points on consumers’ preferences for GM food. We also develop methodological improvements for accurately estimating the value of information on a negative attribute. The project built upon initial findings from a previous AARI project (#AARI Project #2000D037) and is complemented by research supported through a Genome Prairie GE3LS (Genetics, Ethics, Environment, Economics, Law and Society) project: “Commercialization and society: its policy and strategic implications.”Research and Development/Tech Change/Emerging Technologies,

THE INFLUENCE OF ATTRIBUTE CUTOFFS ON CONSUMERS’ CHOICES OF A FUNCTIONAL FOOD

This study investigates evidence of non-compensatory preferences by incorporating attribute cutoffs into the modeling of consumer choices in the context of food with health-related attributes (omega-3 content) that may be associated with fortification or may result from genetic modification (GM). Data for this study were collected through a nation-wide internet-based survey drawn from a representative panel of Canadian households maintained by a major North American marketing firm. In addition to querying respondents on their perceptions and attitudes regarding food and health, choices of canola oils are elicited using a stated choice experiment in which product alternatives are identified based on attributes of price, country of origin, omega-3 content and GM/non-GM derivation. Consumers’ choices for functional canola oil products are examined in three steps. Initially, a conditional logit (CL) model is estimated assuming that no cutoffs apply in decisions on canola oil choices. Respondent’s self-reported cutoffs are then incorporated into the CL model and a random parameters logit (RPL) model, applying a utility model which penalizes rather than eliminates a desired alternative when a cutoff violation occurs. In the third step, the problem of endogeneity associated with attribute cutoffs is examined by linking respondents’ self-reported cutoffs to their demographic characteristics. Results from estimations of models with/without cutoffs show that consumers value omega-3 content in canola oils but dislike GM-derived ingredients in canola oil products. These Canadian respondents prefer canola oils produced in Canada to those produced in the United States. Regarding attribute cutoffs, it is found that consumers suffer a utility loss when violating their self-reported attribute cutoffs. Comparisons between models with/without attribute cutoffs suggest that incorporating cutoffs into the compensatory utility model significantly improves the model fit. Cutoff endogeneity is examined by predicting cutoffs based on respondents’ demographic characteristics. Using predicted cutoffs as instruments for self-reported cutoffs, this study provides some evidence that self-reported cutoffs may be endogenous and that researchers should consider using approaches that account for the potential endogeneity.decision strategy, attribute cutoff, functional food, Agricultural and Food Policy, Consumer/Household Economics, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Health Economics and Policy, C25, C93, D1,