Efficient Heuristics for MRP Lot Sizing with Variable Production/Purchasing Costs*

Two heuristics based on branch and bound (B&B) are developed to solve closed-loop material requirements planning (MRP) lot-sizing problems that have general product structures and variable costs. A “look ahead method'’(LAM) heuristic allows for variable production/purchasing costs and uses a single-level B&B procedure to rapidly improve lower bound values; thus, LAM efficiently uses computer-storage capacity and allows solution of larger problems. The “total average modification'’(TAM) heuristic uses B&B, applied level by level, and modified setup and carrying costs to solve the variable production/purchasing costs MRP lot-sizing problem. LAM and TAM are tested on problems and compared to heuristics in the literature. TAM may be used to solve large MRP lot-sizing problems encountered in practice.     

Relationship Between Household Food Poverty and Vulnerability to Food Poverty: Evidence from Nigeria

Poverty and vulnerability to poverty are major challenges facing developing countries and have attracted the attention of development economists and policy analysts in recent years. This study examined the relationship between household food poverty and vulnerability to food poverty in Nigeria based on data from Nigeria Living Standard Survey (NLSS) (2004) obtained from the National Bureau of Statistics. A least-cost technique associated with the food-energy-intake approach was used to compute zone-specific food poverty lines based on the food baskets common to each geo-political zone; the Foster–Greer–Thorbecke (FGT) poverty index was used in computing food poverty incidence; the three-step feasible generalised least squares (3FGLS) procedure was used in estimating the magnitude of vulnerability to food poverty; cross tabulation and Pearson’s product moment correlation coefficient were utilised for the purpose of analysing the association between household food poverty and vulnerability to food poverty. The food poverty incidence was 50.23 % while the vulnerability to food poverty incidence was 61.68 % and the vulnerability to food poverty/food poverty ratio was 1.228. The food poor were more vulnerable to food poverty than the non food poor. There was significant positive correlation between food poverty incidence and vulnerability to food poverty incidence even though the correlation was not very strong. Thus, policies and programmes that will optimally reduce food poverty and vulnerability to food poverty should be adopted in Nigeria; these should be targeted more on the food poor. This is a major way to break the yoke of underdevelopment in Nigeria.     

Improved randomized response in additive scrambling models

Randomized response models deal with stigmatizing variables appearing in health surveys. Additive and subtractive scrambling in split sample and double response yield unbiased mean and sensitivity estimators of high precision. The split sample method is protective of privacy. The double response method is as protective only conditionally. To achieve the maximum efficiency, the scrambling variables must be similar to each other and the probability of obtaining a true response must be as large as possible. The randomized response procedures yield more efficient estimates of the average total number of classes missed by university students.     

Climate,migration, and the local food security context: introducing Terra Populus

Studies investigating the connection between environmental factors and migration are difficult to execute because they require the integration of microdata and spatial information. In this article, we introduce the novel, publically available data extraction system Terra Populus (TerraPop), which was designed to facilitate population–environment studies. We showcase the use of TerraPop by exploring variations in the climate–migration association in Burkina Faso and Senegal based on differences in the local food security context. Food security was approximated using anthropometric indicators of child stunting and wasting derived from Demographic and Health Surveys and linked to the TerraPop extract of climate and migration information. We find that an increase in heat waves was associated with a decrease in international migration from Burkina Faso, while excessive precipitation increased international moves from Senegal. Significant interactions reveal that the adverse effects of heat waves and droughts are strongly amplified in highly food insecure Senegalese departments.     

The origins and nature of American nationalism

This article critically analyzes the origins and nature of American nationalism. The first part examines the historiographical debate on the question in what period the formation of an American national identity occurred, i.e. before or after the American Revolution. The second part is concerned with the nature of American nationalism, casting doubt on the claim that American nationalism is exceptional, i.e. inherently different and morally superior to other nationalisms. It refutes the exceptionalist claim by applying recent findings in European nationalism research to the American case and by reinterpreting American nationalism not as an introspective phenomenon but as a demarcation process.     

Lifestyle Mobilities: A Politics of Lifestyle Rock Climbing

The conceptualization of ‘lifestyle mobilities’ has yet to fully account for the diversity within and across mobile communities in terms of leisure, travel, and identity. Lifestyle rock climbers, for example, maintain minimalist, hypermobile lifestyles in the full-time, non-professional pursuit of the sport. In an effort to interrogate lifestyle rock climbing within the broader conceptualization of lifestyle mobilities, this paper applies mesotheoretical ‘politics of mobility’ framework. It begins by tracing constellations of mobility and historical contexts within the rock climbing community more broadly. This is followed by an examination of the facets of a politics of mobility: motive force, speed, rhythm, route, experience, friction, turbulence, and remove, which together offer more nuanced understandings of the movement patterns and travel decisions of lifestyle climbing. However, to account for the community dynamics of lifestyle mobilities, there is a need to delve deeper and attend to the social relations that result from collective performances.     

Low‐Income Mothers’ Private Safety Nets and Children’s Socioemotional Well‐Being

Using longitudinal data from the Fragile Families and Child Well‐being Study (N = 1,162) and the National Evaluation of Welfare‐to‐Work Strategies (N = 1,308), we estimate associations between material and instrumental support available to low‐income mothers and young children’s socioemotional well‐being. In multivariate OLS models, we find mothers’ available support is negatively associated with children’s behavior problems and positively associated with prosocial behavior in both data sets; associations between available support and children’s internalizing and prosocial behaviors attenuate but remain robust in residualized change models. Overall, results support the hypothesis that the availability of a private safety net is positively associated with children’s socioemotional adjustment.     

Women's “Justification” of Domestic Violence in Egypt

We explored the influences of women's social learning, marital resources and constraints, and exposure to norms about women's family roles on their views about wife hitting or beating among 5,450 participants in the 2005 Egypt Demographic and Health Survey. One half justified wife hitting or beating for some reason. Women from rural areas who were exposed to domestic violence more often justified such acts. Dependent wives whose husbands had more schooling, were blood relatives, and were coresident more often justified such acts. In settings where women tended to marry at older ages, women less often justified such acts. Women's resources and constraints in marriage accounted for the largest share of the variability in their attitudes about domestic violence against women.     

In Vino Pecunia? The Association Between Beverage-Specific Drinking Behavior and Wages

The positive association between moderate alcohol consumption and wages is well documented in the economic literature. Positive health effects as well as networking mechanisms serve as explanations for the “alcohol–income puzzle.” Using individual-based microdata from the SOEP for 2006, we confirm that this relationship exists for Germany as well. More importantly, we shed light on the alcohol–income puzzle by analyzing, for the first time, the association between beverage-specific drinking behavior and wages. In our analysis, we disentangle the general wage effect of drinking into diverse effects for different types of drinkers. Mincerian estimates reveal significant and positive relationships between wine drinkers and wages as well as between multiple beverage drinkers and wages. When splitting the sample into age groups, the “drinking gain” disappears for employees under the age of 35 and increases in size and significance for higher age groups. We also find a “beer gain” for the oldest age group and male residents of rural areas as well as a “cocktail gain” for residents of urban areas. Several explanations for our empirical results are discussed in view of the likelihood that the alcohol–income puzzle is a multicausal phenomenon.