George Duncan - US grants

As our society balances community needs and individual rights, an energetic data dissemination program by government agencies in support of public policy research must have parity with an effective disclosure limitation program. The substantial growth which has occured in the number of publicly collected microdata files in recent years has made it increasingly difficult, however, to reconcile the public's interest in scientific inquiry with its equally legitimate interest in protecting individual privacy. This project seeks to promote the usefulness of federal statistical data through the development of methodologies that will allow important types of social data to be accessible while assuring an appropriate level of confidentiality. Specifically, the aim is both to develop and evaluate disclosure-limiting techniques that will help guide microdata dissemination. The disclosure-limiting data disseminating approach advanced by Duncan and Lambert in 1985 will be extended to both complete census data and sample data. Examination will be made in the DL context of a variety of proposed disclosure avoidance techniques, for both reidentification and data base query situations. There are four kinds of resolutions between the tension between dissemination and disclosure: ethical guidelines to encourage responsible use of data; administrative rules to control access to data; legal specifications that delineate when data may or may not be used; and statistical techniques to mask data on individuals without compromising information about the group. The approach embraced in this proposal has potential applicability to all four kinds of disclosure limitations. To date, only statistical controls have had any exploration in this framework. The proposed research would effect a significant extension to ethical guidelines, administrative rules, and legal specifications.

Statistical agencies are pivotal in collecting and disseminating the data that guide the health and wealth of our nation. In their mediation between respondents and users, statistical agencies hold two mandates in tension: provide research and policy access to data and assure confidentiality. If an agency fails to properly disseminate data, its data collection is fruitless and wastes taxpayers' money. If the agency fails to protect privacy of respondents, it cannot collect quality data - because of increased nonresponse and evasive response -- and it violates ethical norms. The objective of this research is to develop and evaluate statistical and institutional procedures that better provide confidentiality and data access. The work will build on accomplishments, evidenced by published work, conference presentations, and interactions with statistical agencies, under a current NSF grant. The expansion entails constructing a conceptual model for research and policy access to data, developing and evaluating options for informed consent in data sharing and record linkage, deriving and assessing statistical disclosure limitation procedures based on the concept of matrix masks for public use files, evaluating other restricted access procedures such as licensing agreements, and improving privacy control methods for sequential access to computer databases. Establishment data will receive special attention. The proposed research will effect a significant extension of ethical guidelines, administrative rules, and legal specifications with respect to confidentiality and data access. The issues addressed are becoming increasingly important not only for the individual but for society as a whole.

Calcium plays a critical role in a variety of cell-signalling systems and is increasingly recognised to play a significant part in athe development of cortical cataract. The main aims of this project will be to investigate the mechanisms for achieving calcium homeostasis in the lens and also the sensitivity of these mechanisms to external insult. A further aim will be to elucidate the role of the calcium-activated enzyme, calpain, in the production of lens opacities. Calcium homeostasis will be studied, principally using human lens tissues, but also on athe rat lens in vitro, by a combination of elecrophysiological, radiotracer and fluorimetric dye techniques. Thapsigargin, which selectively inhibits the CaATPase of the endoplasmic reticulum, will be an invaluable tool in these investigations and mathematical modelling techniques will be used to interpret 45Ca flux data from whole human lenses. The sensitivity of calcium permeability (channel) pathways to oxidative insult will also be studied in detail in whole human and rat lenses and in tissue cultured cells. A cation channel antibody will also be used with a combination of immunofluorescence and gold-labelling technique to study the localization of cation channels in lens epithelia and fibre cells. Increases in cytosolic calcium in single lens cells and in whole rat and human lenses will be induced by calcium ionophore (A23187), external membrane SH complexation (pCMPS) and calcium signalling agonists (acetylcholine) and will be quantitatively assayed by the above technique. The effect of these agents on lens transparency will be quantified in whole lens experiments by imaging scattered light. The effect on the lens cytoskeleton (principally actin, tubulin, vimentin and spectrin) will be studied by a combination of DSS-PAGE electrophoresis and immunofluorescence localization techniques. A concomitant study of the colocalization of lens cation channels and cytoskeletal elements will be carried out both in normal and calcium overloaded lens tissues. This study will yield valuable information both on the mechanisms whereby calcium is controlled and also the mechanism responsible for calcium- induced proteolysis and opacification following loss of control. During the course of the project a combined approach will be made that aims both to reduce calcium overload by channel blocking agents and to prevent calcium-induced proteolysis by anti-calpain compounds.

9312143 Duncan This proposal is to develop and evaluate methods to measure and limit disclosure risk in statistical and multilevel relational databases. It addresses the ability of database users to infer sensitive information to which lack authorized access, based on responses to authorized queries. A decision-theoretic approach is proposed to allow analysis as an optimization problem of maximizing access to information subject to constraints on disclosure risk. Building on previous work (e.g., Adam and Wortmann (1989), Denning (1982), Duncan and Mukherjee (1991, 1992), Garvey, Lunt, and Stickel (1991) and Mukherjee, Krishnan, and Duncan (1992), the proposal is to accomplish the following tasks: 1. develop hybrid methods which combine existing disclosure limitation methods for statistical databases, and specify appropriate measures to evaluate their performance; 2. provide a probabilistic framework to evaluate disclosure limitation methods for statistical databases; 3. introduce a methodology that could be used at the time of schema design to detect and eliminate possible inference channels in multilevel relational databases, particularly in the presence of uncertainty about the external information used in the inference process.