Approximation algorithms for <Emphasis Type="Italic">k</Emphasis>-level stochastic facility location problems

In the k-level facility location problem (FLP), we are given a set of facilities, each associated with one of k levels, and a set of clients. We have to connect each client to a chain of opened facilities spanning all levels, minimizing the sum of opening and connection costs. This paper considers the k-level stochastic FLP, with two stages, when the set of clients is only known in the second stage. There is a set of scenarios, each occurring with a given probability. A facility may be opened in any stage, however, the cost of opening a facility in the second stage depends on the realized scenario. The objective is to minimize the expected total cost. For the stage-constrained variant, when clients must be served by facilities opened in the same stage, we present a \((4-o(1))\)-approximation, improving on the 4-approximation by Wang et al. (Oper Res Lett 39(2):160–161, 2011) for each k. In the case with \(k=2,\,3\), the algorithm achieves factors 2.56 and 2.78, resp., which improves the \((3+\epsilon )\)-approximation for \(k=2\) by Wu et al. (Theor Comput Sci 562:213–226, 2015). For the non-stage-constrained version, we give the first approximation for the problem, achieving a factor of 3.495 for the case with \(k = 2\), and \(2k-1+o(1)\) in general.     

Network management and associated firms’ outcomes: multilevel analysis in the southern Brazilian context

This article seeks to provide theoretical and managerial insights with respect to the following questions: What is the effect of network management on the outcomes of associated firms? Do these effects on outcomes vary among small-firm networks (SFNs)? Do these outcomes vary among associated firms within the same SFN? Which management elements are most influential in the variation of these SFN outcomes? To answer these questions, this study adopts a multilevel analytical approach using SFNs in southern Brazil that benefit from the Cooperation Networks Program, a local public policy initiative that supports the formation, development, and consolidation of SFNs. The findings suggest that the outcomes provided by the networks differ between networks but are similar for firms in the same network. They also indicate that strategy and processes at the network level are related to firms’ outcomes. These findings show that the influence of structure on firms’ outcomes varies among networks and that the market segment is the only network-level variable that is significantly related to firms’ outcomes.     

Teaching Decision Theory Proof Strategies Using a Crowdsourcing Problem

Teaching how to derive minimax decision rules can be challenging because of the lack of examples that are simple enough to be used in the classroom. Motivated by this challenge, we provide a new example that illustrates the use of standard techniques in the derivation of optimal decision rules under the Bayes and minimax approaches. We discuss how to predict the value of an unknown quantity, θ ∈ {0, 1}, given the opinions of n experts. An important example of such crowdsourcing problem occurs in modern cosmology, where θ indicates whether a given galaxy is merging or not, and Y₁, …, Y_n are the opinions from n astronomers regarding θ. We use the obtained prediction rules to discuss advantages and disadvantages of the Bayes and minimax approaches to decision theory. The material presented here is intended to be taught to first-year graduate students.     

Imagining Gender Research: Violence,Masculinity, and the Shop Floor

This paper starts by arguing that visual data enriches gender research in management and organizations. Through an analysis of drawings by factory shop‐floor workers, we show that organizational climate is interwoven with gender dynamics, that shop‐floor masculinity is not necessarily heterosexual, and that masculinity in the shop‐floor context includes oppression as an element of man's symbolic violence against man. We discuss the usefulness of this type of data in gender research in organizational analysis and explore the ways in which gender violence is expressed in organizations. Moreover, the drawings gathered at a newspaper printing site located in the North of England provide a means of showing the relationship between gender violence and the exercise of masculinities, sexuality and oppression. We conclude that the exercise of hegemonic masculinity is associated not only with sexuality but also with the oppression of subaltern enactments of masculinity.     

Moving Toward a Holistic Conceptual Framework for Understanding Healthy Aging Among Gay Men

In the last four decades, we have witnessed vast and important transitions in the social, economic, political, and health contexts of the lived experiences of gay men in the United States. This dynamic period, as evidenced most prominently by the transition of the gay rights movement to a civil rights movement, has shifted the exploration of gay men’s health from one focusing primarily on HIV/AIDS into a mainstream consideration of the overall health and wellbeing of gay men. Against this backdrop, aging gay men in the United States constitute a growing population, for whom further investigations of health states and health-related disparities are warranted. In order to advance our understanding of the health and wellbeing of aging gay men, we outline here a multilevel, ecosocial conceptual framework that integrates salient environmental, social, psychosocial, and sociodeomgraphic factors into sets of macro-, meso-, and micro-level constructs that can be applied to comprehensively study health states and health care utilization in older gay men.     

THE EFFECTS OF VARIABLE AND FIXED TRANSACTION COSTS ON OPTIMAL INVESTMENT DECISIONS

This paper studies the impact of variable and fixed transaction costs on investment decisions under conditions of risk. The decision model is first formulated as a mixed-integer nonlinear program. The following subjects are then examined: the structure of the investment frontier facing the investor and the effects of transaction costs on this frontier, the impact of transaction costs on the investor's optimal investment strategy, and the conditions for the equilibrium structure of risky asset prices and risk-return relationships. The main finding is that the relaxation of the assumption of the absence of transaction costs eliminates some of the most unattractive implications of the classic capital asset pricing model (CAPM) while preserving the more attractive implications of this model. Also, our model provides explanations for some discrepancies between the theoretical CAPM and empirical findings and, therefore, is a step toward narrowing the gap between theory and practice.     

Quantifying fear: The social impact of terrorism

This paper proposes a methodology to measure social impact of terrorism. We define a multidimensional terrorism index based not only on deaths but also on other variables such as injuries, bombs and kidnappings. The weight of each terrorist activity is given by its social impact, which is estimated through its relevance in the media. For this task we build up a new data set from the four most important newspapers in Spain, namely, El País, El Mundo, ABC, and La Vanguardia. Finally, we evaluate the social impact of ETA terrorism in Spain from 1993 through 2004.     

Client acceptance decisions of Dutch auditing partners

A vignette study of 567 client acceptance decisions by 67 Dutch auditors showed that the prospect of acquiring additional assignments significantly increases the likelihood that auditing partners accept an audit assignment from a new client, thereby violating a rule of the auditing profession. Audit firm strategy was found to moderate the effect of the acquisition of additional assignments: partners working in audit firms emphasizing a professional orientation are less likely to accept such risky assignments, whereas a commercial orientation of audit firms was found to exacerbate the effect of acquiring additional services. Contrary to expectations, punishment severity for professional mistakes increases the likelihood of client acceptance.

Metabolic and hormonal responses to different resistance training systems in elderly men

Objective: To compare acute and sub-acute responses in hormonal profile and metabolic parameters in elderly people who participated in two methods of strength training (ST) with equalized loads.

Methods and materials: A total of 12 elder individuals (65?±?3 years) were randomly assigned to two training methods: constant intensity (CI, 3 sets of 10 repetitions with 75% of 1RM) and variable intensity (VI, 1st set: 12 repetitions at 67% of 1RM?>?2nd set: 10 repetitions at 75% of 1RM and 3rd set: 8 repetitions at 80% of 1RM). Both methods included the following exercises: leg press, knee extension, and squat with 1?min rest intervals between sets. Free speed of execution and maximum range of movement were encouraged throughout each set for both protocols. Blood samples were analyzed included glucose, testosterone (T), cortisol (C), T/C rate, growth hormone (GH), and lactate at 2 and 24?h post intervention.

Results: There were no observed differences in glucose, testosterone, GH, and lactate concentrations both at 2 and 24?h after the execution of the two training methods. However, significant increases in the levels of T/C rate and decrease on cortisol were observed immediately post exercise for both protocols.

Conclusions: Although no significant differences were observed between the two interventions in relation to the hormonal and metabolic parameters analyzed, both training methods promoted a favorable response, with a slight superiority noted for the CI method relative to the hormonal profile.