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PubMed2001

Limitations of multimedia models for use in environmental decision making.

The United States currently is engaged in a complex, multi-billion dollar effort to cleanup a legacy of both privately- and federally-owned hazardous waste sites. Decisions regarding the best approach for remediation of these sites often are based on the analysis of potential risks to human health and the environment. A cornerstone of such analysis is the frequent use of computerized multimedia environmental transport models, to evaluate the large quantities of information necessary to understand the present and future implications of contamination at a site. One barrier to wide-spread use of this analytical procedure is the view that results obtained using computer models are highly dependent on user input, and therefore, subject to manipulation. It is widely recognized that for decisions to be both credible and implementable, the public must have confidence in both the scientific basis for judgments involved and the decision processes employed (NRC, 1983). Our purpose in this article is to overview the difficulties associated with application of multimedia models to real world problems and the contribution these models can make to technically sound estimates of exposure and risk.

Benchmarking↗
PubMed1997

Radiation sterilization of formoterol.

PURPOSE: Radiation sterilization is becoming increasingly popular for the sterilization of many pharmaceutical products. We have investigated the gamma radiation induced effects on formoterol fumarate by HPLC and ESR spectroscopy. RESULTS AND DISCUSSION: Numerical simulation of the evolution of the ESR signal versus dose was performed using linear regression, quadratic fit and power function. The shape of the dosimetric curve is linear in the range 5-30 kGy. Owing to the weak number of free radicals generated during the irradiation, the accuracy of measurements is low. For a dose of 25 kGy, discriminating irradiated from unirradiated samples is possible if the storage period is less than 250 days. The comparison between chromatographic profiles of irradiated and unirradiated samples showed minor differences. CONCLUSIONS: From our preliminary results, radiosterilization of formoterol fumarate may be technically feasible. Estimation of the irradiation dose by ESR may be possible but, due to the weak number of free radicals generated during the irradiation, the accuracy of measurements appeared low.

Chromatography, High Pressure Liquid↗
PubMed1975

Beta2 microglobulin and lymphocytic infiltration in Sjögren's syndrome.

We measured salivary beta2 microglobulin concentrations in 49 patients evaluated for Sjögren's syndrome with a labial salivary-gland biopsy. The salivary concentration was elevated and a significant correlation (P less than 0.001) was found between the concentration and the degree of inflammation seen in the biopsy. Serum concentrations were increased in 135 patients with Sjögren's syndrome. Striking elevations were seen in patients with associated renal or lymphoproliferative complications. Three patients have an increase in serum beta2 microglobulin concentration in association with exacerbation of their disease, and six a decrease after clinically efficacious therapy. These data indicate that determination of beta2 microglobulin in saiva may provide a simple, noninvasive technic for estimation of the degree of local inflammation in autoimmune disease.

Adrenal Cortex Hormones↗
PubMed1976

The swine-influenza decision.

We analyzed the economic aspects of mass immunization against swine-like influenza in 1976-1977, and have used the Delphi technic for estimating the likelihood and characteristics of an epidemic. If an epidemic occurs and no preventive efforts are made, total costs could exceed $6 billion for the whole population and $3 billion for those in the high-risk group. Expected net benefits from immunization vary with (1) the target population, (2) costs of vaccine administration and (3) vaccine acceptance rates. With an epidemic probability of 0.10 and with costs of purchasing and administering the vaccine each estimated at $0.50 per person in the target population, maximum net benefits cannot be obtained by an offer of vaccine to the entire population. Economic considerations do not require limitation of vaccination to high-risk groups. If the program is restricted to adults 25 years of age and over, and if acceptance rates exceed 59 per cent, the program is economically justifiable.

Adult↗
PubMed1992

Effect of the Gulf War on infant and child mortality in Iraq.

BACKGROUND: Increased malnutrition and morbidity among Iraqi children after the onset of the Persian Gulf war have been reported by several fact-finding missions. The magnitude of the effect of the war and the economic embargo on child mortality remains uncertain, however. METHODS: We conducted a survey of 271 clusters of 25 to 30 households each, chosen as a representative sample of the Iraqi population. The households were selected and the interviews conducted by an international team of public health professionals independent of Iraqi authorities. In each household all women 15 to 49 years of age were interviewed, and the dates of birth and death of all children born on or after January 1, 1985, were recorded. RESULTS: The study population included 16,076 children, 768 of whom died during the period surveyed (January 1, 1985, to August 31, 1991). The age-adjusted relative mortality for the period after the war began, as compared with the period before the war, was 3.2 (95 percent confidence interval, 2.8 to 3.7). No material change in the relative risk was observed after adjustment for region of residence, maternal education, and maternal age. The increase in mortality after the onset of the war was higher among children 1 to less than 12 months old (relative risk, 4.1; 95 percent confidence interval, 3.3 to 5.2) and among those 12 to less than 60 months old (relative risk, 3.8; 95 percent confidence interval, 2.6 to 5.4) than among those less than 1 month old (relative risk, 1.8; 95 percent confidence interval, 1.4 to 2.4). The association between the war and mortality was stronger in northern Iraq (relative risk, 5.3) and southern Iraq (relative risk, 3.4) than in the central areas (relative risk, 1.9) or in Baghdad (relative risk, 1.7). CONCLUSIONS: These results provide strong evidence that the Gulf war and trade sanctions caused a threefold increase in mortality among Iraqi children under five years of age. We estimate that more than 46,900 children died between January and August 1991.

Child, Preschool↗
PubMed1982

Spatial aggregation in gravity models: 2. One-dimensional population density models.

"This paper, the second of four, is concerned with applying a methodology for analysing the spatial aggregation problem in gravity models outlined in the first paper. The methodology is based on a consistent framework for linking measures of pattern in interaction data to the derivation and estimation of related interaction models using spatial information. In this quest, a link is forged between information in data and the parameters of an associated model.... This relationship can be formalised for the case of the continuous one-dimensional interaction model such as the population density model, and this paper is concerned with demonstrating such an application to aggregations of zones in the Reading [England] region."

Demography↗
PubMed1982

Spatial aggregation in gravity models: 4. Generalisations and large-scale applications.

"This paper is concerned with applying and extending a methodology for analysing spatial aggregation in gravity models developed in three earlier papers to a larger scale and hence more realistic example of spatial interaction than has been treated so far." Seven models are generated and applied to four levels of aggregation of the spatial interaction pattern in Edmonton, Alberta.

Americas↗
PubMed1982

Estimation of migration profiles in England and Wales.

"Migration profiles by age have been increasingly used in the analysis of migration data, and a theoretical function has been developed by researchers at the International Institute for Applied Systems Analysis (IIASA). This paper refines the approach by applying the principles of maximum likelihood to the estimation of the coefficients for the function. This enhances the statistical basis and in particular enables [the authors] to carry out tests of similarity between different areas on the basis of the calibrated coefficients. The method is applied to 1971 Census data for the local authorities of England and Wales."

Age Factors↗
PubMed1983

Patterns of family migration: two methodological approaches.

"It is widely recognized that many internal migrations are undertaken by individuals whose moves are dependent on those of others. For example, children migrate with their parents and wives with their husbands. This paper suggests two formulations of family migration that permit the introduction of such family dependencies into the population projection process."

Demography↗
PubMed1983

Analysis of gross migration profiles in England and Wales: some developments in classification.

"In this paper [the authors] describe the development and application of two approaches to the analysis of age and sex specific interarea migration. The data relate to local authority areas in England and Wales. These approaches are developments of established migration profile-fitting and cluster analytic methods. The paper shows how these methods have been used to develop complementary classifications from which potentially valuable criteria for migration analysis can emerge. The work described is part of a wider project concerned with the development of methods to improve the official estimation of internal migration in England in the context of local area population forecasting."

Age Factors↗
PubMed1984

Ecological fallacies and the analysis of areal census data.

The author examines problems related to the fact that in many countries, census data are only reported for areal units and not at the individual level. Attention is paid to the question of ecological fallacy problems that arise from this situation. Data from a 10 percent sample of the United Kingdom population and individual census data from Italy are used to illustrate the problem. "It is concluded that ecological fallacy effects are endemic to areal census data, although their magnitude is perhaps not as large as might have been expected. The principal difficulty is that there is at present no way of predicting in advance the degree of severity likely to be associated with particular variables and particular techniques. Finally, a suggestion is made concerning how the potentially serious practical consequences can be reduced."

Censuses↗
PubMed1984

A partial hierarchical regionalization of 3,140 US counties on the basis of 1965-1970 intercounty migration.

"Because of a special tabulation recently completed by the US Bureau of the Census for the 1965-1970 period, interareal migration flows--for the first time--can be examined on the level of the 3,140 counties.... Preliminary results, restricted to six (of a theoretically possible 3,139) levels, are discussed here. They provide some indications of the full results, as well as an upper bound (40,000) on the number of largest doubly standardized values it is necessary to consider in the full clustering."

Americas↗
PubMed1985

Economic-demographic modeling with endogenously determined birth and migration rates: theory and prospects.

"The standard demographic approach to population forecasting consists of extrapolating into the future carefully measured birth, death, and migration rates. An alternative is to forecast changes in those rates on the basis of social science theories. In this paper the prospects for incorporating those theories into forecasting models are assessed. The paper has two parts, the first devoted to fertility and the second to migration. Each contains a description of the demographic methods currently used by the US Bureau of the Census followed by a comprehensive review of the theoretical foundations for forecasting and an assessment of the prospects for doing so."

Americas↗
PubMed1985

Economic-demographic models for forecasting interregional migration.

"A class of spatial economic-demographic forecasting models is proposed. The models combine elements of traditional Markov and economic gravity models. A base-period probability structure is modified by the changing relative distribution of economic opportunity. Estimation issues are addressed, and an empirical application to US interstate migration during the late 1970s is described. It is contended that the framework represents a merger of past demographic and economic modeling traditions in a spatial interaction framework."

Americas↗
PubMed1985

The household-composition matrix as a notion in multiregional forecasting of population and households.

"The household-composition matrix has been used in the past for single-region projection of population and households; here the application is expanded to multiregional projection of population and households. Geographic regions of residence are considered as household categories, and a household-composition matrix is constructed to indicate average numbers of persons by age per household, for each of the regions considered." The method is illustrated using data for the city of Edmonton, Canada. Changes over time due to population aging and to observed patterns of household mobility are considered. "These patterns are listed as six possible household mobility types, which in turn, are viewed as constraints within which population growth takes place. With the assumption that external net-migration to the regions, as a whole, is known for a projected period, an iterative procedure is offered to estimate future population by age and region, as well as future number and average size of households by region."

Age Distribution↗
PubMed1985

Distance-weighted geographic interpolation.

"The results of estimates of population density for individual states of the United States of America are compared with those obtained previously by Kennedy and Tobler. The new estimates are much simpler to calculate and of equal accuracy. However, neither method utilises geographical information."

Americas↗