A spanning heuristic for the unordered and ordered matching identification problem

The matching identification problem (MIP) is a combinatoric search problem related to the fields of learning from examples, boolean functions, and knowledge acquisition. The MIP involves identifying a single “goal” item from a large set of items. Because there is commonly a cost associated with evaluating each guess, the goal item should be identified in as few guesses as possible. As in most search problems, the items have a similar structure, which allows an evaluation of each guessed item. In other words, each guessed item elicits partial information about the goal item, i.e. how similar the guess is to the goal. With this information the goal is more quickly identified.The unordered MIP has been studied by Mehrez and Steinberg (ORSA J. Comput. 7 (1995) 211) in which they proposed two different types of algorithms. The purpose of the present paper is to suggest an improved Spanning Heuristic algorithm. Its improvement increases as the problem size increases. Further results and comparisons are derived for the unordered and ordered cases.This research shows that when the search space is very large, it is better to inquire from items that are known not to be the goal (they have been ruled out by previous guesses), for the purpose of acquiring more information about the goal. As the search space is narrowed, it is better to guess items that have not been ruled out.     

Relationships among nutrients,chloride and biological indices in urban Maryland streams

Using a spatially extensive urban database constructed from the Maryland Biological Stream Survey (MBSS), we describe the relationships of nutrients in small-order streams to eight defined categories of percent catchment urbanization, correlations between chloride and conductivity in urban streams, and relationships between nutrients and chloride with two Maryland-specific indices of biotic integrity for benthic macroinvertebrates and fish assemblages. Stream nutrients become elevated with increasing percent catchment urbanization, followed by increases in all four measured nitrogen species and total phosphorus at catchment urbanization levels greater than 10%. There was a strong collinear relationship (r ² = 0.90) between chloride and conductivity (trimeans) across all eight urbanization classes, where Cl (mg/L) = −0.397 + 0.188*conductivity (μS/cm). Critical values for all water quality parameters with the two Maryland biological indices were derived using quantile regression, with significant regressions developed for 11 of 16 water quality parameters and the two biotic indices. For nitrate (NO₃-N), the critical thresholds between fair and poor stream quality for the two Maryland biological indices were 0.83 mg/L (benthic macroinvertebrate assemblages) and 0.86 mg/L (fish assemblages). Increasing stream nutrient and chloride levels, associated with widespread catchment urbanization intensity, now affect many small streams in Maryland, with implications for decreasing water quality in major tributaries and the Chesapeake Bay.     

Promoting Fathers' Engagement With Children: Preventive Interventions for Low‐Income Families

Few programs to enhance fathers' engagement with children have been systematically evaluated, especially for low‐income minority populations. In this study, 289 couples from primarily low‐income Mexican American and European American families were randomly assigned to one of three conditions and followed for 18 months: 16‐week groups for fathers, 16‐week groups for couples, or a 1‐time informational meeting. Compared with families in the low‐dose comparison condition, intervention families showed positive effects on fathers' engagement with their children, couple relationship quality, and children's problem behaviors. Participants in couples' groups showed more consistent, longer term positive effects than those in fathers‐only groups. Intervention effects were similar across family structures, income levels, and ethnicities. Implications of the results for current family policy debates are discussed.     

‘Being friends means helping each other,making coffee for each other’: reciprocity in the friendships of people with intellectual disability

Friendship is an issue of concern for many people with intellectual disability. The aim of the research presented in this paper is to understand how people with intellectual disability experience friendship and what friendship means for them. A focus group was held with seven people with intellectual disability, who are members of a self-advocacy group. An inductive thematic analysis approach was used to analyse the data. The people that the research participants identified as their friends were fellow self-advocates, family members, support workers and co-workers. They also identified behaviours and actions that foster friendship and those that undermine it. The analysis shows how the research participants identified as friendships those relationships which had an element of reciprocity, while linking a lack of reciprocity with the absence of friendship. It is very important for non-disabled people to understand the perspectives of people with intellectual disability they live and work with.     

Best practice in couple relationship education

Relationship education is widely available to couples and is intended to reduce the prevalence of relationship distress, divorce, and the associated personal and social costs. To realize the potential benefits of couple relationship education, it needs to be evidence-based, offered in ways that attract couples at high-risk for relationship problems, and focused on factors that put couples at high-risk for future relationship problems.     

Causes of accidents and the time of day

Abstract

The relationship between accidents and the time of day is not entirely clear. Although there is considerable evidence that performance is poorest in the early morning hours compared to at all other times, the degree to which this is translated into accidents is not understood. In this study work-related fatal accidents were analysed to determine whether the causes of these accidents vary with time. The analysis used a classification and coding system devised to describe the wider circumstances of the causes of fatalities. In terms of absolute numbers, fatalities were most common in the late morning or early afternoon. When these results were expressed in terms of the estimated number of workers at work, the proportion of fatal accidents occurring at night was more than double that occurring during the day. Behavioural factors were the most common cause of fatalities at all times, but most common in the early hours of the morning. Further analysis of the nature of the behavioural involvement showed that errors in automatic processing (skill-based errors) were the most common types of error and did not vary much with time of day. Rule-based errors were most common during the day whereas knowledge-based errors occurred mainly in the afternoon and night shifts. These results cast some doubt on the assumption that there is a direct relationship between the previously observed variations in performance across time and the ultimate safety outcome.     

Work and rest in the long-distance road transport industry in Australia

To date management of fatigue in professional drivers has largely focused on strategies that limit the amount of time spent on the job. These approaches have, however, not taken into account the well-documented effect of time of day. Consequently, the likely impact of the pattern and timing of work and rest has received little attention. The results revealed that the group of drivers who did the shortest trips and worked the shortest weekly hours were the lowest reporters of fatigue, although longer hours were not always associated with the highest reporting of fatigue. In contrast, the shortest working hours were associated with earliest onset of fatigue. For all drivers, the influence of circadian rhythms was evident in the occurrence of fatigue, with better management of the problem evident among drivers who were able to arrange the timing of rest to more closely coincide with periods of fatigue. Thus, time of day appeared to be a more important influence in determining effective rest than did period of work. These findings raise questions about the validity of the assumption underlying work hour regulations for long-distance drivers which, currently, are universally based on duration of work.     

Does the degree of relative risk aversion vary with household characteristics?

This study examines household risk taking, using Swedish cross-sectional data based on tax returns from more than 7000 households for 1985. In contrast to previous studies, this study recognizes that households compose different risky portfolios because of their varying characteristics. This study also recognizes real assets as investment goods and takes into account the gains from diversification that emerge when real assets and financial assets are combined. The estimated risk aversion was found to be very large but not systematically correlated with any of the included variables, with the exception of age. The estimated age coefficient suggests that risk aversion increases with age.     

Enabling everything: scale,disability and the film The Theory of Everything

This article looks at the representation of scale in the 2014 film The Theory of Everything, identifying moments that relate to three concerns: firstly, how disabled people experience scale issues at an all too practical level in daily life; secondly, how Hawking’s experience of scale at the level of both body and mind is (a)typical of the way it is experienced by disabled people generally; and, thirdly, how a focus on the film can prompt some rethinking of perspectives both within disability studies and within the conceptualisation of scale more broadly.