Scheduling and packing malleable and parallel tasks with precedence constraints of bounded width

We study the problems of non-preemptively scheduling and packing malleable and parallel tasks with precedence constraints to minimize the makespan. In the scheduling variant, we allow the free choice of processors; in packing, each task must be assigned to a contiguous subset. Malleable tasks can be processed on different numbers of processors with varying processing times, while parallel tasks require a fixed number of processors. For precedence constraints of bounded width, we resolve the complexity status of the problem with any number of processors and any width bound. We present an FPTAS based on Dilworth’s decomposition theorem for the NP-hard problem variants, and exact efficient algorithms for all remaining special cases. For our positive results, we do not require the otherwise common monotonous penalty assumption on the processing times of malleable tasks, whereas our hardness results hold even when assuming this restriction. We complement our results by showing that these problems are all strongly NP-hard under precedence constraints which form a tree.     

Identifying factors for poorer educational outcomes that may be exacerbated by COVID-19: A systematic review focussing on at-risk school children and adolescents

School closures across Australia in response to COVID-19 have persisted since 2020, with rising mental health problems in children and adolescents, alongside rising negative family health and socioeconomic outcomes. Further, some children and young people who were already experiencing disadvantage pre-pandemic may be at heightened risk of poorer educational outcomes. Therefore, the aim of this study was to conduct a systematic review of the literature to identify the factors for poorer educational outcomes that may be exacerbated by COVID-19 amongst disadvantaged school students. Key development stages of disadvantage were identified: young children who started school behind, older students already at risk of disengagement from school and children and young people who have had contact with the child protection system. Five databases were systematically searched, across two search periods. A total of 69 Australian, peer-reviewed articles, published in 2005–2021, examining risk factors for poor educational outcomes for children attending school met the inclusion criteria and were included in final analyses. Our findings provide evidence of key risk factors that make these populations susceptible to worsening outcomes resulting from the COVID-19 pandemic, and of the critical importance of ongoing research to guide policy and practice support for these at-risk groups.     

Leveraging risk assessment for foodborne outbreak investigations: The Quantitative Risk Assessment-Epidemic Curve Prediction Model

Root cause analysis can be used in foodborne illness outbreak investigations to determine the underlying causes of an outbreak and to help identify actions that could be taken to prevent future outbreaks. We developed a new tool, the Quantitative Risk Assessment-Epidemic Curve Prediction Model (QRA-EC), to assist with these goals and applied it to a case study to investigate and illustrate the utility of leveraging quantitative risk assessment to provide unique insights for foodborne illness outbreak root cause analysis. We used a 2019 Salmonella outbreak linked to melons as a case study to demonstrate the utility of this model (Centers for Disease Control and Prevention [CDC], 2019). The model was used to evaluate the impact of various root cause hypotheses (representing different contamination sources and food safety system failures in the melon supply chain) on the predicted number and timeline of illnesses. The predicted number of illnesses varied by contamination source and was strongly impacted by the prevalence and level of Salmonella contamination on the surface/inside of whole melons and inside contamination niches on equipment surfaces. The timeline of illnesses was most strongly impacted by equipment sanitation efficacy for contamination niches. Evaluations of a wide range of scenarios representing various potential root causes enabled us to identify which hypotheses, were likely to result in an outbreak of similar size and illness timeline to the 2019 Salmonella melon outbreak. The QRA-EC framework can be adapted to accommodate any food–pathogen pairs to provide insights for foodborne outbreak investigations.     

Sexual orientation and self-employment: New evidence

Early studies and theory suggest sexual minorities are drawn towards the relative independence of self-employment to avoid discrimination in paid employment. However, recent evidence is mixed, suggesting that a higher propensity for self-employment (relative to heterosexual people) is found only among lesbian women relative to heterosexual women. This study overcomes the data limitations of prior research by using data pooled from 2007–2017 cycles of the Canadian Community Health Survey (CCHS) and multivariate logistic regression to provide new evidence on LGB self-employment. The results show that self-employment is particularly high for bisexual people, especially bisexual women—but not for gay men or lesbian women. Overall, this study examines the enduring but nuanced relationship between self-employment and sexual orientation and discusses countervailing factors related to socio-economic resources, gender, and family structure.     

The intersections of race,immigrant status,and university confirmations in Toronto

Although the number of students attending university has been steadily increasing over the past 20 years, discrepancies remain across racialized student groups. Students who immigrate to Canada also face a number of barriers to university participation. However, few studies investigate variations in university participation across racialized immigrant student groups. We draw on an intersectional approach to analyze student data from the Toronto District School Board. We employ multilevel logistic regression to examine if there are interactive effects of being both racialized and having an immigrant status on confirming a university enrollment. Looking at self-identified race and immigrant status of students in combination reveals that there are important differences in the likelihood of confirming and offer of university admission between several self-identified racial categories, depending on if they were foreign-born.     

Rainbow Research: Challenges and Recommendations for Sexual Orientation and Gender Identity and Expression (SOGIE) Survey Design

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - A growing number of people around the world identify, in some way, as Lesbian, Gay, Bisexual, Transgender, and Queer...     

Bacterial communities in peat swamps reflect changes associated with catchment urbanisation

Urban Ecosystems - Like many peat wetlands around the world, Temperate Highland Peat Swamps on Sandstone (THPSS), located in the Sydney Basin, Australia, have been impacted by urban development. In...