Multi‐Echelon Inventory Management under Short‐Term Take‐or‐Pay Contracts

We extend the Clark–Scarf serial multi‐echelon inventory model to include procuring production inputs under short‐term take‐or‐pay contracts at one or more stages. In each period, each such stage has the option to order/process at two different cost rates; the cheaper rate applies to units up to the contract quantity selected in the previous period. We prove that in each period and at each such stage, there are three base‐stock levels that characterize an optimal policy, two for the inventory policy and one for the contract quantity selection policy. The optimal cost function is additively separable in its state variables, leading to conquering the curse of dimensionality and the opportunity to manage the supply chain using independently acting managers. We develop conditions under which myopic policies are optimal and illustrate the results using numerical examples. We establish and use a generic one‐period result, which generalizes an important such result in the literature. Extensions to cover variants of take‐or‐pay contracts are included. Limitations are discussed.     

联盟组合多样性及其与绩效维度的关系

基于480家机构的以自我为中心的网络数据,分析了联盟组合多样性和财务绩效、激进式创新绩效、渐进式创新绩效等三个重要绩效维度之间的关系.其中,联盟组合多样性与财务绩效负相关;而联盟组合多样性与激进式创新绩效呈现倒U形关系;联盟组合多样性与渐进式创新绩效呈现递减收益正相关.结果表明,管理者应该意识到联盟组合多样性的可能的消极影响,并且意识到不同水平的联盟组合多样性是最有益的.     

Controlling epileptic seizures in a neural mass model

In an effort to understand basic functional mechanisms that can produce epileptic seizures, we introduce some key features in a model of coupled neural populations that enable the generation of seizure-like events and similar dynamics with the ones observed during the route of the epileptic brain towards real seizures. In this model, modified from David and Friston’s neural mass model, an internal feedback mechanism is incorporated to maintain synchronous behavior within normal levels despite elevated coupling. Normal internal feedback quickly regulates an abnormally high coupling between the neural populations, whereas pathological internal feedback can lead to hypersynchronization and the appearance of seizure-like high amplitude oscillations. Feedback decoupling is introduced as a robust seizure control strategy. An external feedback decoupling controller is introduced to maintain normal synchronous behavior. The results from the analysis in this model have an interesting physical interpretation and specific implications for the treatment of epileptic seizures. The proposed model and control scheme are consistent with a variety of recent observations in the human and animal epileptic brain, and with theories from nonlinear systems, adaptive systems, optimization, and neurophysiology.     

Individual Differences in the Pathways into and Beyond Higher Education in the UK: A Life-Course Approach

This article uses data from the UK 1970 Birth Cohort ( N = 10,000) to address the research questions: (a) Who in this cohort made the transition to higher education (HE), and (b) how are the benefits and risks of such participation distributed? We assess the way that the benefits and risks of participation differ according to family background and child development, finding risks to mental health for individuals who attend HE against the odds. We also explore the errors in prediction of standard statistical models in order to introduce a discussion of selection bias linked to a broader policy question of the appreciation of the complexity and idiosyncrasy of individuals' educational pathways. We explore this question in relation to three particular cases that confound the prediction of the statistical analysis in order to clarify the assumptions and limitations of a standard analysis in approaching the problems of developing policy that recognizes individual heterogeneity and diversity .     

An analysis of conservation attitudes and awareness around Kaziranga National Park,Assam, India: implications for conservation and development

Kaziranga National Park and World Heritage Site, Assam, India, situated in a region with a large and diverse human population, was recently expanded due to its global importance for the conservation of many endangered species. Here, we develop detailed demographic and socio-economic profiles of residents around Kaziranga to study conservation attitudes and awareness using a semi-structured survey of 590 households in 37 villages. Results show high variation in attitudes and awareness as a function of ethno-religious group, educational level, and socio-economic and immigration status, indicating more and different needs for economic interventions within some communities than others. We found a high degree of conservation awareness, but most people expressed negative conservation attitudes and almost all lost crops to wildlife. We highlight the complexity of conflict in the area and present a basis for electing a microsite planning approach for conservation and development in areas characterized by high ethnic diversity, high human population densities, and land-dependent large mammals that pose economic risks. The findings imply that highly localized development schemes and participatory approaches to resource management at the village level, coupled with greater efforts at education, are especially needed to achieve conservation and development goals in such cases.     

Science as a Strategy for Social Work

For more than one hundred years, various forms of science have been promoted to boost social work’s status as a profession. Evidence-based practice and talk about the science of social work are only the most recent manifestations of this pattern. Counter to this trend, this article argues that the latest upsurge of interest in scientific social work is no more likely than any of its predecessors to address the problems of the profession. Beginning with a linguistic analysis of the words science and scientific as positive signifiers, the article traces social work’s long history of science talk as a means of reassuring funding agencies and bolstering the profession’s status. Drawing on a critique of this discourse as the latest example of abstracted empiricism, it then contends that while scientific social work can only rarely capture what occurs in the field, its attempt to do so actually undercuts practitioners’ professional judgment and discretion. Last, after rejecting science talk as counterproductive, the article concludes with recommendations for an alternative strategy that might better position social work to reconcile its advocacy of social justice with its concerns about its professional status.     

Land ownership,the subsistence constraint,and the demographic transition

We develop a novel model of fertility choice predicting an increase and subsequent decrease in fertility levels without introducing a quality–quantity tradeoff, mortality changes, or urbanization. The model highlights the roles of a subsistence constraint and non-wage income deriving from the ownership of land. We show that the sign of the effect of the wage rate on fertility depends on whether non-wage income is greater or less than a minimum consumption level. Suggestive evidence supporting the model, on changes in fertility from 1851 to 1891 across French départements, is provided. Finally, we embed our static model in a model of endogenous growth, and provide a numerical illustration of the working of the model.     

Conflict Versus Consensus Strategic Orientations Among Environmental NGOs: An Empirical Evaluation

Israeli environmental non-government organizations (ENGOs) are assessed in light of Resource Mobilization Theory, introducing a new method for dividing ENGOs according to strategic orientation. Based on a national survey, 85 groups are categorized as consensus ENGOs that seek understanding aim at finding common grounds, or as conflict ENGOs working “outside the system.” Results show that conflict ENGOs are more grassroots in orientation and consensus ENGOs are more professionalized. Conflict ENGOs operate primarily in local arenas. Consensus ENGOs appear more stable, with larger annual budgets and paid staff, but with fewer registered members. Consensus ENGOs enjoy a wider variety of income sources; receive more funding from government, foreign, and private donations; and have a broader range of self-generated income sources. Conflict ENGOs depend more on membership fees. Both groups are highly dependent on foundation grants. In general, greater resources are associated with consensus activity than among organizations utilizing conflict tactics.     

Committee Decision Making in Organizations: An Experimental Test of the Core

One concept that has been widely supported in experiments on predicting the outcome of majority-rule voting committees is the Core, the set of alternatives that cannot be defeated by any other in a binary contest. Unfortunately, the applicability of these experiments to organizations is limited by a set of rigid controls intended to ensure that the experiments are internally valid. This paper tests the Core in a laboratory environment that relaxes these controls. The Core is found to be highly predictive under these relaxed conditions, thereby enhancing confidence in its external validity.