Interpreting demographic effects in duration analyses of first birth intervals

Estimated demographic effects in proportional hazard models of first birth intervals could reflect time-invariant differences in the risk of a birth, or differences in the timing of a shift in the risk, or both. This paper attempts to distinguish between these possibilities. The procedure is to estimate a more general model than the proportional hazard specification, in which the evolution of the risk of a birth can differ with demographic characteristics. The proportional hazard specification is nested within this more general model. Consequently, the consistency of the data with the risk or the timing interpretation of demographic effects can be tested. The data studied do not lead to a rejection of the proportional hazard specification.Department of Economics, University of Pennsylvania. The initial stage of this research was supported by a National Science Foundation Graduate Fellowship. I have benefited from insightful comments from David Bloom, Andrew Foster, Zvi Griliches, V. Joseph Hotz, Duncan Thomas, anonymous referees, and participants in seminars at Harvard University and the University of Pennsylvania, and in the Economic Demography sessions of the 1988 Population Association of America annual meetings. Any remaining errors are my own.     

Migration from Latin American countries to the United States: the economic,social and reproductive lives of Hispanic female immigrants, 1980

The authors describe the socioeconomic characteristics and fertility patterns of female immigrants from Latin America to the United States, with a focus on reasons for fertility differentials. "Using the one per cent public use sample from the 1970 and 1980 United States census, we first compare changes in socio economic characteristics from 1970 to 1980, and then examine the determinants of fertility of female immigrants to the United States, aged 16-49, from four Latin American areas or countries of birth.... The findings...suggest that there are direct effects of demographic, assimilation, and socioeconomic variables beyond those mediated by the variables in each of these sets. Further, regardless of the model, the effect of the clusters of demographic characteristics is most apparent. Age categories and marital status are the strongest indexed determinants of immigrant fertility.... The effect of education and employment is strong. Among assimilation variables, duration of residence and language ability are significant determinants of Hispanic immigrant fertility." (SUMMARY IN FRE AND SPA)     

A new two-party bargaining mechanism

If resources and facilities from different partners need to be engaged for a large-scale project with a huge number of tasks, any of which is indivisible, decision on the number of tasks assigned to any collaborating partner often requires a certain amount of coordination and bargaining among these partners so that the ultimate task allocation can be accepted by any partner in a business union for the project. In the current global financial crisis, such cases may appear frequently. In this paper, we first investigate the behavior of such a discrete bargaining model often faced by service-based organizations. In particular, we address the general situation of two partners, where the finite Pareto efficient (profit allocation) set does not possess any convenient assumption for deriving a bargaining solution, namely a final profit allocation (corresponding to a task assignment) acceptable to both partners. We show that it is not appropriate for our discrete bargaining model to offer the union only one profit allocation. Modifying the original optimization problem used to derive the Nash Bargaining Solution (NBS), we develop a bargaining mechanism and define a related bargaining solution set to fulfil one type of needs on balance between profit-earning efficiency and profit-earning fairness. We then show that our mechanism can also suit both Nash’s original concave bargaining model and its continuous extension without the concavity of Pareto efficient frontier on profit allocation.     

Integrated scheduling and inventory management of an oil products distribution system

The oil supply chain is facing new challenges due to emerging issues such as new alternative energy sources, oil sources scarcity, and price variability with high impact on demand and production and profit margins reduction. Additionally, the existence of large, complex and world wide spread businesses implies a complex system to be managed where distribution can be seen as one of the key areas that needs to be efficiently and effectively managed. Different types of distribution modes characterize the oil supply chain where the pipeline mode is one of the most complex to operate when having multiproduct characteristics. This paper addresses the planning of a generic oil derivatives transportation system characterized by a multiproduct pipeline that connects a single refinery to a storage tank farm. Two alternative mixed integer linear programming models (MILP) that aim to attain a set of planning objectives such as fulfilling costumers’ demands (which is mandatory) while minimizing the medium flow rate are developed. Additionally, final inventory levels are avoided to be excessively low. A real world scenario of a Portuguese company is used to validate and compare the two alternative MILP models developed in this paper.     

Übertragung und Gegenübertragung im Coaching

The author describes the use of psychoanalytic concepts in coaching work. At first, the classical issue of transference and its modern forms will be discussed, later the classical issue of countertransference and its modern forms. Finally, the author presents two case studies on transference and countertransference in coaching work.     

Nutrient intake in day workers and shift workers

Abstract

The 24-h dietary intake, nutritional status parameters and psychosomatic factors of two-shift, three-shift and day workers were compared. Estimations of the dietary intake (across a work cycle) were made by use of a nutrient database. No significant differences were found between the groups for a large number of nutritional variables: intake of energy; intake and percentage of energy from protein, fat, total carbohydrates and sucrose; intake of coffee; and intake and density of vitamins and minerals. Only minor differences were found between the groups with regard to the quantitative intake of alcohol and calcium, and with regard to the quality of the diet (percentage of energy from alcohol, density of calcium). The groups differed significantly with respect to attitude towards work hours (three-shift workers being most negative in their attitude) and sleep disturbances (shift workers being most negative). The three-shift workers were more evening-oriented and they had higher concentrations of glucose in their blood. It was concluded that work hours not related to nutritional intake—at least not when total amounts across time are considered. It was also concluded that work hours were not related to Body Mass Index or blood lipids: triglycerides, total cholesterol, LDL (low-density lipoprotein) cholesterol and HDL (high-density lipoprotein) cholesterol.     

Changes in the structure of health complaints as related to shiftwork exposure

Abstract

Factor analyses of health complaints in groups with different length of shiftwork exposure show that the structure of these complaints changes with increasing shift experience, indicating the emergence of a shift-specific pattern of health complaints. After about 15 years of shiftwork, complaints related to disturbances of circadian-controlled functions can be found in the first factor whereas other complaints have their dominant loadings on a separate factor, representing general, non-shift-specific impairments. The results indicate that in this way shift-specific components of health impairment can be separated from other non-shift related components.     

Neuroticism,locus of control,type A behaviour pattern and occupational stress

Abstract

The aim of this study was to investigate the relationship between individual differences in personality and susceptibility to stress in the workplace. Stress in lecturers employed by a computer training organization was assessed by means of self-report and measurement of salivary cortisol output during lecturing and non-lecturing weeks. Neuroticism, Type A behaviour pattern and locus of control were measured. Self-reported stress was found to be much greater during lecturing weeks, but cortisol levels were unaffected by working conditions. There was a significant positive correlation between neuroticism and locus of control and a negative correlation between locus of control and Type A behaviour pattern that approached significance. Multiple regression was employed to explore relations between personality and stress. Subjects with lower neuroticism scores yielded a bigger increase in reported stress, in the lecturing compared with the non-lecturing week, than subjects with high neuroticism scores. Type B subjects showed a progressive decrease in cortisol over the working week while Type A counterparts showed a resurgence of cortisol towards the end of the week. Finally, Type B subjects having an internal locus of control showed a faster decline in cortisol level during the lecturing week than the other subjects. Implications of these results are discussed in terms of the importance simultaneously incorporating a variety of individual differences in personality dimensions and stress indices in research designs.     

The impact of non-bottleneck variation in a manufacturing cell

Protective capacity is the 'extra' capacity placed at non-bottleneck resources to absorb random disruptions in planned levels of performance so that the bottleneck resource continues to be effectively utilized. A full factorial experiment with a simulation model was conducted to explore issues associated with the quantity and location of processing variance in a five-station manufacturing cell. The cell's performance was measured using both mean flow time ( MFT ) and bottleneck shiftiness ( SHIFT ) for 3 patterns of variance for the non-bottlenecks at 5 different levels of variation. In order to investigate the importance of the quantity of added capacity on the variation both a low level of protective capacity (10%) and a high level (50%) were considered. The results indicate that having the higher variation work centres close to the bottleneck provides reduced MFT and SHIFT . The performance measures improved at both the low and high setting of protective capacity.