Centralized inventory in a farming community

A centralized inventory problem is a situation in which several agents face individual inventory problems and make an agreement to coordinate their orders with the objective of reducing costs. In this paper we identify a centralized inventory problem arising in a farming community in northwestern Spain, model the problem using two alternative approaches, find the optimal inventory policies for both models, and propose allocation rules for sharing the optimal costs in this context.     

Modeling Risk‐Related Knowledge in Tunneling Projects

Knowledge on failure events and their associated factors, gained from past construction projects, is regarded as potentially extremely useful in risk management. However, a number of circumstances are constraining its wider use. Such knowledge is usually scarce, seldom documented, and even unavailable when it is required. Further, there exists a lack of proven methods to integrate and analyze it in a cost‐effective way. This article addresses possible options to overcome these difficulties. Focusing on limited but critical potential failure events, the article demonstrates how knowledge on a number of important potential failure events in tunnel works can be integrated. The problem of unavailable or incomplete information was addressed by gathering judgments from a group of experts. The elicited expert knowledge consisted of failure scenarios and associated probabilistic information. This information was integrated using Bayesian belief‐networks‐based models that were first customized in order to deal with the expected divergence in judgments caused by epistemic uncertainty of risks. The work described in the article shows that the developed models that integrate risk‐related knowledge provide guidance as to the use of specific remedial measures.     

Major Factors Influencing the Health Impacts from Controlling Air Pollutants with Nonlinear Chemistry: An Application to China

Predicting the human‐health effects of reducing atmospheric emissions of nitrogen oxide (NO_x) emissions from power plants, motor vehicles, and other sources is complex because of nonlinearity in the relevant atmospheric processes. We estimate the health impacts of changes in fine particulate matter (PM_2.5) and ozone concentrations that result from control of NO_x emissions alone and in conjunction with other pollutants in and outside the mega‐city of Shanghai, China. The Community Multiscale Air Quality (CMAQ) Modeling System is applied to model the effects on atmospheric concentrations of emissions from different economic sectors and geographic locations. Health impacts are quantified by combining concentration‐response functions from the epidemiological literature with pollutant concentration and population distributions. We find that the health benefits per ton of emission reduction are more sensitive to the location (i.e., inside vs. outside of Shanghai) than to the sectors that are controlled. For eastern China, we predict between 1 and 20 fewer premature deaths per year per 1,000 tons of NO_x emission reductions, valued at $300–$6,000 per ton. Health benefits are sensitive to seasonal variation in emission controls. Policies to control NO_x emissions need to consider emission location, season, and simultaneous control of other pollutants to avoid unintended consequences.     

Migration Patterns During Italian Urbanization, 1865-1921

This study examines patterns of male migration in central Italy during its transformation from an agrarian to an urban-industrial society. The Italian population registers provide data on the extent and type of emigration among more than 3,500 men (ages 10 and over) who immigrated to the commune of Casalecchio di Reno, bordering the city of Bologna, from 1865 to 1915. Demographic and social differentials in overall rates of emigration and their relation to places of origin and destination are measured. The implications of these results for an understanding of population mobility are discussed.     

Income sufficiency v. poverty Results from the United States and The Netherlands

The purpose of this paper is to further the understanding of subjective measures used to assess poverty and to add to the literature on poverty measurement methodology. In particular, the paper focuses on the minimum income question (MIQ) first proposed by Goedhart and colleagues (1977). Data from the U.S. Consumer Expenditure Survey and from a Dutch newspaper survey are used. The primary contribution of the paper is the inclusion of household expenditures as additional explanatory variables of minimally necessary income. Significant differences between the coefficients of several categories of expenditures, particularly for leisure, appear to reveal differences in the interpretation of the minimum income question by respondents. Thus, we question the underlying assumption of the MIQ that everyone adheres the same welfare meaning to the phrase “minimally necessary income,” and conclude that the resulting thresholds should not be used as to measure poverty before further research has been carried out to explore what respondents are thinking when they answer questions such as the MIQ.     

Forensic demography and civil rights

In the summer of 1965, the legislature of the state of Mississippi passed a law which required children whose parents were living in another state to pay up to $350 tuition in order to attend public school. On the belief that this law discriminated against Negroes and was therefore unconstitutional, the Department of Justice began litigation procedures to repeal it. But evidence was needed to prove that the law was in fact discriminatory. The lawyers contacted demographers at the Bureau of the Census to provide data to determine if the majority of persons affected were Negro and too poor to pay the tuition. They sought information which could tell them, ideally, how many parents of children in Mississippi had left the state and what the economic position and racial characteristics of the children were.An attempt was made to get this information from already published sources, such as census reports and other research findings. These could give a hurried impression of the situation but could not deal directly with the issue of the whereabouts of parents not living with their children, since such a question had not been asked in the 1960 Census. An additional bit of information was obtained from the NAAGP Legal Defense and Education Fund in Jackson, Mississippi, from forms showing characteristics of persons actually affected by the law. But this limited sample did not provide evidence solid enough upon which to build a case.It was decided to rely on a retabulation of 1960 Census records to describe accurately the base population from which children with parents out of state would be drawn-namely, the children not living with either parent. This showed that of all school-age children living without either parent, 82 percent are Negro. The average Negro household, which contains at least one "parentless" child, houses 6.8 persons and has an annual income of $1,429. This allows less than $250 annually per person. Tuition for just one child eats up more than one person's yearly allotment. These data showed that the law, in fact, did discriminate racially, since most of the persons affected were Negro and too poor to pay tuition.This was one instance in which demographers were able to use their special skills in implementing public policy-notably, the law.     

Change, continuity or cycles: The population turnaround in New South Wales

This study examines population flows from Sydney and other regions to perimetropolitan and coastal areas of New South Wales, the two main foci of the population turnaround since 1971. It uses census internal migration statistics for the five intercensal periods between 1971 and 1996, and estimated resident population statistics between 1997 and 2000. Fluctuating trends are described with respect to variations in age structures of migration flows and net migration gains by SLAs in coastal areas over time. Evidence of fluctuating trends is evaluated in relation to population structure change and local socio-economic multipliers in turnaround areas. The turnaround is far mor than a net migration gain from large metropolitan areas; it is also associated with interregional migration which avoids metropolitan areas, and which is at least in part environment- and amenity-related. The experience of some other countries, such as the USA where net migration reversals in population turn-around regions have occurred, has not been replicated in Australia. While elements of explanation for the complex cumulative causation process of the population turnaround in Australia are discussed, including the issues of fluctuating or cyclical trends, much more understanding of the economic and social factors involved is required.     

Life table analysis of the green rice leafhopper,Nephotettix virescens (distant) (Hemiptera: Cicadellidae), and efficient vector of rice tungro disease in asynchronous rice fields in Indonesia

Summary Population dynamics ofNephotettix virescens was studied in 17 paddy fields transplanted at intervals of about 1 month in 1988–1990. The adult density was highest either in the immigrant or the 1st generation and sharply decreased to the 2nd generation. The survival rate of the 1st generation was lowest in the transition season when areal population density increased. Key factor analysis revealed that the nymphal and adult mortality of the 1st generation (kn) was the principal source of population fluctuations. No significant correaltion was found between kn and natural enemy density, natural enemy density/healthy egg density, or the precipitation during the nymphal period. On these bases adult emigration was suspected to be the key factor. Areal population build-up ofN. virescens in the transition season was considered to occur as a result of increasing immigration to young stages of rice. Contribution from Indonesia-Japan Joint Program on Food Crop Protection (ATA 162), which was implemented by the Directorate of Food Crop Protection, Ministry of Agriculture, Indonesia and Japan International Cooperation Agency, Japan.