Designing Organisational Management Frameworks to Empower Episodic Volunteering

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - Volunteers are a critical operational resource for not-for-profit organisations in the health and welfare sector. However,...     

The Effects of Middle School Weight Climate on Youth With Higher Body Weight

This study examines whether social‐emotional difficulties associated with higher body weight vary across schools as a function of the school's weight climate. Weight climate, characterized by weight‐policing, was assessed indirectly by examining how strongly self‐reported weight predicts victim reputation within 26 ethnically diverse middle schools. Social‐emotional indicators included self‐reported loneliness, school belonging, and self‐esteem. In schools with stronger weight‐policing at seventh grade, loneliness was intensified by eighth grade among both girls (n = 2,101) and boys (n = 1,985) with higher weight. Similar effects were found for low self‐esteem among girls. Additionally, boys—regardless of their weight—reported lower sense of belonging in schools with stronger weight‐policing. The study offers a new method to estimate school weight climate, and the findings provide insights for interventions.     

Exposure to Parent and Peer Alcohol Use and the Risk of Drinking Onset and Escalation Among Adolescents

Although the rate of alcohol use among adolescents has declined, it remains their drug of choice. Parent and peer alcohol use are powerful risk factors for youth alcohol use. However, questions remain about how these factors influence underage drinking. The present study investigates the relationship between exposure to parent or peer alcohol use and two stages of adolescent drinking—onset and escalation—overall and at five age points during adolescence. Participants were 9348 adolescents in Waves I (WI) and II (WII) of the National Longitudinal Study of Adolescent Health, whose parents completed interviews at WI, and who identified themselves as either non-drinkers or experimental drinkers at WI. Reports of WII alcohol use were used to measure onset among WI non-drinkers and escalation among WI experimenters. Risk ratios were calculated to assess the overall impact of exposure to parent or peer alcohol use on onset and escalation, and at five age points (i.e., ≤?13, 14, 15, 16, and ≥?17). Findings show that exposure to either parent or friend alcohol use increased the risk of onset and escalation. Age-based analyses reveal a more nuanced relationship, showing variability in the nature and strength of influence by stage of drinking and by age. This study highlights the relevance of both parent and peer modeling on youth drinking throughout adolescence. Implications in advancing prevention and treatment include parental education about the impact of their own behaviors and the importance of monitoring teens’ friendships.     

The Relational Contexts of Migration: Mexican Women in New Destination Sites

This article assesses Mexican immigrant women's experiences of isolation and autonomy in three new destination sites in Montana, Ohio, and New Jersey. We highlight six case studies from our cross‐comparative data set of in‐depth interviews and field work with 98 women to illustrate the intersections between contexts of reception and gender relations in shaping women's settlement experiences. We find that women in sites with a concentrated Mexican population and a well‐developed social service infrastructure are relatively autonomous in accomplishing daily activities independent of their relationships with husbands or partners. In contrast, for women living in sites with few social support services, relationships with the men in their lives, what we call their “relational contexts,” matter for women's experiences of isolation or autonomy outside the home. Relational contexts have not been emphasized in previous literature on gender and migration but may be significant in shaping women's experiences across varying contexts of reception.     

Property Size and Land Cover Change in the Brazilian Amazon

This paper considers the size of a farmer’s property as a key variable influencing land cover and land cover change in rural areas of developing countries. Data from 126 rural familial properties in the region around the city of Santarém, Pará, in the Brazilian Amazon, indicate that property size is important for understanding the trajectories of land cover change. Past research has focused on the distinction between small family farms and large capitalized farms, arguing that family farmers have a higher deforestation intensity, or on estimating the strength of the effect of property size relative to economic or demographic factors. This paper shows that larger familial properties are able both to retain a larger area in forest and to have long enough cycles of use and fallow to allow previously used land to become forested again. Based on these analyses and discussion, we argue that land use and land cover research must consider property size as an organizing principle in order to better comprehend the reciprocal relationship between population and environment in frontier areas of the Brazilian Amazon and other rural landscapes.     

Online scheduling with rejection and reordering: exact algorithms for unit size jobs

We study an online scheduling problem with rejection on \(m\ge 2\) identical machines, in which we deal with unit size jobs. Each arriving job has a rejection value (a rejection cost or penalty for minimization problems, and a rejection profit for maximization problems) associated with it. A buffer of size \(K\) is available to store \(K\) jobs. A job which is not stored in the buffer must be either assigned to a machine or rejected. Upon the arrival of a new job, the job can be stored in the buffer if there is a free slot (possibly created by evicting other jobs and assigning or rejecting every evicted job). At termination, the buffer must be emptied. We study four variants of the problem, as follows. We study the makespan minimization problem, where the goal is to minimize the sum of the makespan and the penalty of rejected jobs, and the \(\ell _p\) norm minimization problem, where the goal is to minimize the sum of the \(\ell _p\) norm of the vector of machine completion times and the penalty of rejected jobs. We also study two maximization problems, where the goal in the first version is to maximize the sum of the minimum machine load (the cover value of the machines) and the total rejection profit, and in the second version the goal is to maximize a function of the machine completion times (which measures the balance of machine loads) and the total rejection profit. We show that an optimal solution (an exact solution for the offline problem) can always be obtained in this environment, and determine the required buffer size. Specifically, for all four variants we present optimal algorithms with \(K=m-1\) and prove that in each case, using a buffer of size at most \(m-2\) does not allow the design of an optimal algorithm, which makes our algorithms optimal in this respect as well. The lower bounds hold even for the special case where the rejection value is equal for all input jobs.     

The cost of selfishness for maximizing the minimum load on uniformly related machines

Consider the following scheduling game. A set of jobs, each controlled by a selfish agent, are to be assigned to m uniformly related machines. The cost of a job is defined as the total load of the machine that its job is assigned to. A job is interested in minimizing its cost, while the social objective is maximizing the minimum load (the value of the cover) over the machines. This goal is different from the regular makespan minimization goal, which was extensively studied in a game theoretic context. We study the price of anarchy (poa) and the price of stability (pos) for uniformly related machines. The results are expressed in terms of s, which is the maximum speed ratio between any two machines. For uniformly related machines, we prove that the pos is unbounded for s>2, and the poa is unbounded for s≥2. For the remaining cases we show that while the poa grows to infinity as s tends to 2, the pos is at most 2 for any s≤2.     

Selfish bin coloring

The bin packing problem, a classical problem in combinatorial optimization, has recently been studied from the viewpoint of algorithmic game theory. In this bin packing game each item is controlled by a selfish player minimizing its personal cost, which in this context is defined as the relative contribution of the size of the item to the total load in the bin.