Container Scheduling: Complexity and Algorithms

We consider the transport of containers through a fleet of ships. Each ship has a capacity constraint limiting the total number of containers it can carry and each ship visits a given set of ports following a predetermined route. Each container has a release date at its origination port, and a due date at its destination port. A container has a size 1 or size 2; size 1 represents a 1 TEU (20‐foot equivalent unit) and size 2 represents 2 TEUs. The delivery time of a container is defined as the time when the ship that carries the container arrives at its destination port. We consider the problem of minimizing the maximum tardiness over all containers. We consider three scenarios with regard to the routes of the ships, namely, the ships having (i) identical, (ii) nested, and (iii) arbitrary routes. For each scenario, we consider different settings for origination ports, release dates, sizes of containers, and number of ports; we determine the computational complexity of various cases. We also provide a simple heuristic for some cases, with its worst case analysis. Finally, we discuss the relationship of our problems with other scheduling problems that are known to be open.     

Begegnung als ethische Maxime und Intervention im Coaching

Just as there is no universal understanding of what constitutes Coaching, there are no generally accepted ethical standards within Coaching. Opinions as to ethics within Coaching spring largely from the various ??Schools?? which transmit Coaching methods. Coaches working with J. L. Moreno??s Psychodrama follow the ethical and philosophical outlook contained in the analysis of creativity, spontaneity, the ??Social Atom?? and in the method, process orientated ??Encounter?? as understood by Moreno and Buber. That which they have internalised as ethical maxim and the Encounter method, is also understood to be a fundamental intervention.     

Information Aggregation in Dynamic Markets With Strategic Traders

This paper studies information aggregation in dynamic markets with a finite number of partially informed strategic traders. It shows that, for a broad class of securities, information in such markets always gets aggregated. Trading takes place in a bounded time interval, and in every equilibrium, as time approaches the end of the interval, the market price of a “separable” security converges in probability to its expected value conditional on the traders' pooled information. If the security is “non‐separable,” then there exists a common prior over the states of the world and an equilibrium such that information does not get aggregated. The class of separable securities includes, among others, Arrow–Debreu securities, whose value is 1 in one state of the world and 0 in all others, and “additive” securities, whose value can be interpreted as the sum of traders' signals.     

The modest effects of fact boxes on cancer screening

Journal of Risk and Uncertainty - As health care becomes increasingly personalized to the needs and values of individual patients, informational interventions that aim to inform and debias consumer...     

Optimal Inventory Control with Retail Pre‐Packs

A pre‐pack is a collection of items used in retail distribution. By grouping multiple units of one or more stock keeping units (SKU), distribution and handling costs can be reduced; however, ordering flexibility at the retail outlet is limited. This paper studies an inventory system at a retail level where both pre‐packs and individual items (at additional handling cost) can be ordered. For a single‐SKU, single‐period problem, we show that the optimal policy is to order into a “band” with as few individual units as possible. For the multi‐period problem with modular demand, the band policy is still optimal, and the steady‐state distribution of the target inventory position possesses a semi‐uniform structure, which greatly facilitates the computation of optimal policies and approximations under general demand. For the multi‐SKU case, the optimal policy has a generalized band structure. Our numerical results show that pre‐pack use is beneficial when facing stable and complementary demands, and substantial handling savings at the distribution center. The cost premium of using simple policies, such as strict base‐stock and batch‐ordering (pre‐packs only), can be substantial for medium parameter ranges.     

The simultaneous examination of economic and social factors in destination selection: Employing objective and subjective measures

This research examines the role of social and economic factors in the past selection of destinations made by migrants living in Rhode Island. Results indicate that social ties play a more important role in the selection of destinations with low levels of opportunity than they do in the movement to high opportunity areas. An important aspect of the study was the simultaneous investigation of both objective and subjective measures of social and economic factors in the selection of low and high growth destinations. The analysis suggests that the simultaneous consideration of objective and subjective factors provides a more refined accounting of the potential influence of social and economic factors in the selection of destinations. The findings hold when age is introduced as a control.     

Asset Accumulation And Family Size

Utilizing panel data on families, estimates are made of the effects of children on asset accumulation, asset composition, consumption, and family income. Young children are found to depress savings for young families but to increase savings for marriages of duration greater than five years. The principal channel through which children act to reduce savings is the decline in female earnings associated with the child-induced withdrawal of wives from the labor force. Family consumption actually decreases with the birth of a child, but this reduction is insufficient, for young families, to offset the fall in income. For families in which the wife does not work the estimates suggest that savings may actually increase with children.     

Length of residence,social ties,and economic opportunities

This study examines length of residence for movers—that subsection of the population which accounts for the high mobility rates in the United States. The propensity for repeated migration is studied in relation to economic opportunities and previous familial and personal contacts. The results indicate no influence of economic opportunities on duration of residence. This finding is consistent with recent research that indicates economic conditions are not a general stimulus for out-migration, although they are for in-migration. On the other hand, length of residence is found to be longer where previous familial and personal contacts existed. Overall, the results provide additional evidence of the importance of social, as opposed to strictly economic, variables in the migration process.     

Urbanization and the fertility transition in Ghana

This paper examines the way in which migration and urban residence operate to alter fertility outcomes. While urban-rural fertility differentials have long been established for most developing societies, the nature of these differences among migrants and between migrants and those of succeeding generations is not well understood. The evidence presented here suggests that rural-urban migration and urbanization may contribute positively to processes of fertility transition. Using data from the 1998 Kumasi Peri-Urban Survey, which included a 5-year retrospective monthly calendar of childbearing, we suggest that migrants adapt quickly to an urban environment. Our results also reveal generational differences in recent and cumulative fertility. While migrants exhibit higher cumulative fertility than urban residents of the second and third generation, their fertility is significantly lower than rural averages in Ghana. Children of migrants exhibit childbearing patterns quite similar to those in higher-order generations. Most noteworthy is the nature of the disparities in childbearing patterns between migrants and the succeeding generations. Migrant women have higher lifetime fertility than urban natives. Migrant women also exhibit higher fertility over the last 5 years than second generation or high-order urban natives. But these first generation women exhibit lower fertility (vs. urban natives) for the year immediately prior to the survey. These patterns lend support to an interpretation that combines rather than opposes theories of selectivity, disruption, adaptation and socialization. We conclude by discussing mechanisms that might explain these interrelated processes of fertility adjustment and suggest that policies discouraging rural-urban migration need to be revisited.