Dynamic proportional hazard rate and reversed hazard rate models

Cox (1972) proportional hazard (PH) model has been used to model failure time data in Reliability and Survival Analysis. Recently, proportional reversed hazard model has been analyzed in the literature. Sometimes, the hazard rate (or the reversed hazard rate) may not be proportional over the whole time interval, but may be proportional differently in different intervals. In order to take care of this kind of problems, in this paper, we introduce the dynamic proportional hazard rate model, and the dynamic proportional reversed hazard rate model, and study their properties for different aging classes. The closure of the models under different stochastic orders has also been studied. Examples are presented to illustrate different properties of the models.     

An Empirical Investigation of the Contribution of Strategic Sourcing to Manufacturing Flexibilities and Performance*

Empirical studies for achieving manufacturing flexibility goals have centered around the uses and advantages of advanced technology. Few studies have examined alternative ways of attaining flexibility objectives. Strategic sourcing finds mention in the literature as a potential route to manufacturing flexibility. However, little empirical evidence exists to validate this view. Literature also describes manufacturing flexibility as a multidimensional concept but fails to adequately examine the synergies among the different dimensions. This research investigates the influence of strategic sourcing and advanced manufacturing technologies on specific manufacturing flexibilities, and examines relationships among different flexibilities. The results are tied to manufacturing cost reduction. The findings suggest that strategic sourcing can assist in the achievement of modification flexibilities. Volume and modification flexibility are found to influence new product flexibility. Modification flexibility is found to influence manufacturing cost reduction. The results show that strategic sourcing can be used to target specific manufacturing flexibilities and that interflexibility synergies need to be considered while formulating flexibility-based manufacturing strategies.     

The Effects of Alcohol in Breast Milk on Infant Behavioral State and Mother‐Infant Feeding Interactions

The short‐term impact of infant exposure to alcohol in breast milk on mother‐infant interactions and infant arousal was examined. Fourteen mother‐infant dyads were tested on 2 occasions that consisted of an alcohol administration and a nonalcohol condition. Mother‐infant interactions during feeding were videotaped and coded for dyadic reciprocity, maternal noncontingency, and dyadic conflict. Infants were observed for 1 hr after receiving either plain breast milk or breast milk containing alcohol. Behavioral state, startles, and tremors were recorded every 30 sec. Mother‐infant interactions were characterized by higher noncontingency and dyadic conflict in the alcohol condition. After drinking breast milk containing alcohol, infants changed behavioral state more often, startled more, and spent less time in quiet sleep and more time in quiet alert and crying states. These findings suggest that exposure to breast milk containing alcohol may not have a sedating effect, as commonly believed.     

Managerial Perceptions and the Essence of the Managerial World: What is an Interloper Business Executive to Make of the Academic‐Researcher Perceptions of Managers?

I argue that the Mezias and Starbuck (2003) research programme misses being managerially relevant by investigating the extent of perceptual inaccuracies among managers rather than the more valuable question of from where these inaccuracies arise and what their consequences are in practice. As a sometime business executive, it seems to me that the closer one gets to an actual managerial position, the less significant some of the explanations and recommendations in the academic research literature appear as regards managerial concerns. To ensure relevance in the managerial research enterprise, I suggest that academics should make concrete efforts to become reasonably conversant with the managerial world before undertaking any empirical research. I also make the point that the discussion of the Mode 2 approach to knowledge production in the management field needs to move away from the current focus on straightforwardly 'bridging the relevance gap' and toward finding ways to improve the competence of Mode 2 researchers by insisting on a minimum understanding of the managerial world before embarking on management research.     

A semiparametric Bayesian approach for joint modeling of longitudinal trait and event time

Inference on the whole biological system is the recent focus in bioscience. Different biomarkers, although seem to function separately, can actually control some event(s) of interest simultaneously. This fundamental biological principle has motivated the researchers for developing joint models which can explain the biological system efficiently. Because of the advanced biotechnology, huge amount of biological information can be easily obtained in current years. Hence dimension reduction is one of the major issues in current biological research. In this article, we propose a Bayesian semiparametric approach of jointly modeling observed longitudinal trait and event-time data. A sure independence screening procedure based on the distance correlation and a modified version of Bayesian Lasso are used for dimension reduction. Traditional Cox proportional hazards model is used for modeling the event-time. Our proposed model is used for detecting marker genes controlling the biomass and first flowering time of soybean plants. Simulation studies are performed for assessing the practical usefulness of the proposed model. Proposed model can be used for the joint analysis of traits and diseases for humans, animals and plants.     

The Tradeoffs of Inclusionary Zoning: What Do We Know and What Do We Need to Know?

Inclusionary zoning (IZ), a controversial planning tool for supplying affordable housing, grew significantly during the 2000s' housing boom in the USA. We review the resultant scholarly literature on IZ. Our key reading is that IZ can include both tradeoffs and practical efforts to address them. There is also a need for additional research. More specifically, we find that IZ programs (i) have many components and vary considerably; (ii) can increase affordable housing production and social integration, but there can be a tradeoff between these goals; and (iii) can have slight adverse market effects, but cost-offsets can help mitigate the outcomes. Finally, we discuss the need for more research, particularly in-depth case studies and make suggestions.     

Risk,Process Maturity,and Project Performance: An Empirical Analysis of US Federal Government Technology Projects

In recent years, there has been increasing pressure on the US federal government to reduce spending and improve the management of its technology projects. Mitigating the adverse impact of risks on the performance of these projects presents a significant challenge for its stakeholders. Our research examines this challenge in two steps. First, we identify and define a set of salient risks in federal technology projects—specifically, complexity risk and contracting risk in the planning process, and execution risk in the execution process. Next, we investigate whether higher levels of process maturity, assessed by the Capability Maturity Model Integration (CMMI) framework, mitigate the negative effect of project risks on project performance. The analysis of time‐series data collected from 82 federal technology projects across 519 quarterly time periods indicates that each of the three types of risks has a significant negative effect on project performance. This finding highlights the practical significance of managing these risks in the federal technology project context. Further, we find that increasing levels of process maturity attenuate the negative effect of project risks on the performance of federal technology projects. However, the attenuation effects are consequential only at high levels of project risks; at low levels of project risk, increasing levels of process maturity can adversely affect project performance. To demonstrate the financial implications of increasing process maturity levels in federal technology projects, we examine the magnitude of project cost savings (and overruns) across different levels of CMMI and project risks. In summary, our study contributes to the sparse literature on public sector operations by addressing the understudied context of federal technology projects, and provides a nuanced examination of the implications of process maturity in managing the risk to performance relationship in such projects.     

Does Female Disadvantage Mean Lower Access to Food?

The literature on gender differentials in nutrition demonstrates that the calorie intake of females is generally as adequate as that of males at all ages. Female disadvantage in micronutrient intake is, however, frequent. Pregnant and lactating women are disadvantaged relative to both men and other women. In South Asia there is evidence that boys are advantaged over girls in food intake at some ages, but the evidence for male advantage in access to health care is far stronger. The authors argue that nutrition interventions are best targeted when the incidence of female disadvantage is better understood and, similarly, that interventions to improve women's status should be focused on objectives other than calorie intake in most communities. However, standards for measuring adequacy incorporate norms for female body size and physical activity that may uncritically accept the notion that females are more physically passive. Maintaining adequacy by these standards could perpetuate low levels of female functioning.     

An ergonomic study on the onset of mental fatigue among the load handling workers of a central market area in Kolkata

It is a well recognized fact that manual material handling (MMH) entails enormous physical labor and associated discomfort feeling, which invariably culminate into musculoskeletal disorders. However mental fatigue, in such instances, becomes an unexplored parameter that needs definite attention during assessment of work status of MMH workers. The present study is being performed among 75 porters of a central market in Kolkata to ascertain the extent of physical and mental exhaustion among them. SF-12 health status questionnaire followed by another questionnaire involving psychosocial questions were performed among them. The analysis of both the questionnaires clearly revealed that most of the porters are under severe physical exertion as they alone carry about 120 kg load at a time and such activity is repeated at least 40 times throughout the day. They always suffer from pain and discomfort feeling at different body parts and this interferes with their normal work activity to a great extent. Moreover absenteeism means no financial return and even a day's rigourous work fetches meagre income. The inability to support family convincingly even after performing such hazardous tasks makes them feel low. Monotony, boredom, fatigue and mental trauma form an integral part of their daily work schedule.