Dimension Reduction via Colour Refinement

Colour refinement is a basic algorithmic routine for graph isomorphism testing, appearing as a subroutine in almost all practical isomorphism solvers. It partitions the vertices of a graph into "colour classes" in such a way that all vertices in the same colour class have the same number of neighbours in every colour class. Tinhofer (Disc. App. Math., 1991), Ramana, Scheinerman, and Ullman (Disc. Math., 1994) and Godsil (Lin. Alg. and its App., 1997) established a tight correspondence between colour refinement and fractional isomorphisms of graphs, which are solutions to the LP relaxation of a natural ILP formulation of graph isomorphism. We introduce a version of colour refinement for matrices and extend existing quasilinear algorithms for computing the colour classes. Then we generalise the correspondence between colour refinement and fractional automorphisms and develop a theory of fractional automorphisms and isomorphisms of matrices. We apply our results to reduce the dimensions of systems of linear equations and linear programs. Specifically, we show that any given LP L can efficiently be transformed into a (potentially) smaller LP L' whose number of variables and constraints is the number of colour classes of the colour refinement algorithm, applied to a matrix associated with the LP. The transformation is such that we can easily (by a linear mapping) map both feasible and optimal solutions back and forth between the two LPs. We demonstrate empirically that colour refinement can indeed greatly reduce the cost of solving linear programs

Effectiveness of interventions using self-monitoring to reduce sedentary behavior in adults : a systematic review and meta-analysis

Background: Sedentary behavior occurs largely subconsciously, and thus specific behavior change techniques are needed to increase conscious awareness of sedentary behavior. Chief amongst these behavior change techniques is self-monitoring of sedentary behavior. The aim of this systematic review and meta-analysis was to evaluate the short-term effectiveness of existing interventions using self-monitoring to reduce sedentary behavior in adults. Methods: Four electronic databases (PubMed, Embase, Web of Science, and The Cochrane Library) and grey literature (Google Scholar and the International Clinical Trials Registry Platform) were searched to identify appropriate intervention studies. Only (cluster-)randomized controlled trials that 1) assessed the short-term effectiveness of an intervention aimed at the reduction of sedentary behavior, 2) used self-monitoring as a behavior change technique, and 3) were conducted in a sample of adults with an average age >= 18 years, were eligible for inclusion. Relevant data were extracted, and Hedge's g was used as the measure of effect sizes. Random effects models were performed to conduct the meta-analysis. Results: Nineteen intervention studies with a total of 2800 participants met the inclusion criteria. Results of the meta-analyses showed that interventions using self-monitoring significantly reduced total sedentary time (Hedges g = 0,32; 95% CI = 0,14 - 0,50; p = 0,001) and occupational sedentary time (Hedge's g = 0,56; 95% CI = 0,07 - 0,90; p = 0,02) on the short term. Subgroup analyses showed that significant intervention effects were only found if objective self-monitoring tools were used (g = 0,40; 95% CI = 0,19 - 0,60; p < 0,001), and if the intervention only targeted sedentary behavior (g = 0,45; 95% CI = 0,15-0,75; p = 0,004). No significant intervention effects were found on the number of breaks in sedentary behavior. Conclusions: Despite the small sample sizes, and the large heterogeneity, results of the current meta-analysis suggested that interventions using self-monitoring as a behavior change technique have the potential to reduce sedentary behavior in adults. If future - preferably large-scale studies - can prove that the reductions in sedentary behavior are attributable to self-monitoring and can confirm the sustainability of this behavior change, multi-level interventions including self-monitoring may impact public health by reducing sedentary behavior

Assessing cycling-friendly environments for children: are micro-environmental factors equally important across different street settings?

BACKGROUND: As physical activity levels decrease as children age, sustainable and accessible forms of physical activity are needed from a young age. Transportation cycling is one such physical activity and has been associated with many benefits. The aims of the study were to identify whether manipulating micro-environmental factors (e.g. speed limis, evenness of cycle path) within a photographed street influences the perceived supportiveness for transportation cycling; and whether changing these micro-environmental factors has the same effect across different street settings. METHODS: We recruited 305 fifth and sixth grade children and their parents from twelve randomly selected primary schools in Flanders, Belgium. They completed a web-based questionnaire including 12 choice-based conjoint tasks, in which they had to choose between two possible routes depicted on manipulated photographs, which the child would cycle along. The routes differed in four attributes: general street setting (enclosed, half open, open), evenness of cycle path (very uneven, moderately uneven, even), speed limit (70&nbsp;km/h, 50&nbsp;km/h, 30&nbsp;km/h) and degree of separation between a cycle path and motorised traffic (no separation, curb, hedge). Hierarchical Bayes analyses revealed the relative importance of each micro-environmental attribute across the three street settings. RESULTS: For each attribute, children and their parents chose routes that had the best alternative (i.e. open street setting, even cycle path, 30&nbsp;km/h, a hedge separating the cycle path from motorised traffic). The evenness of the cycle path and lower speed limit had the largest effect for the children, while the degree of separation and lower speed limit had the largest effect for their parents. Interactions between micro-scale and macro-scale factors revealed differences in the magnitude but not direction of their effects on route choice. The results held across the different kinds of street settings tested. CONCLUSIONS: Improving micro-scale attributes may increase the supportiveness of a street for children\u27s transportation cycling. We call for on-site research to test effects of changes in micro-environmental attributes on transportation cycling among children

Bulletin No. 132 - Minor Dry Land Crops at the Nephi Experiment Farm

The investigations conducted at the Nephi substation deal primarily with cereals; other crops, such as alfalfa, peas, corn, potatoes, etc., have occupied only a secondary position in the work of this station. This necessarily has been true because the experiments are confined to dry-land practices, and the cereals unquestionably comprise the basal crops for dry-land farming as it is now understood and practiced in Utah. No crops have been found as yet which yield so profitably on the dry lands as do the cereals, especially winter varieties. The purpose of this bulletin is to review the work done on the Nephi substation with crops other than cereals, and to point out the possible utilization of the results obtained. Both success and failure have been experienced in this work, with no truly startling results; but sufficient promising data are included in the results to warrant publication at this time. It is believed that the publication of these results will stimulate further efforts along these lines

Social Interactions vs Revisions, What is important for Promotion in Wikipedia?

In epistemic community, people are said to be selected on their knowledge contribution to the project (articles, codes, etc.) However, the socialization process is an important factor for inclusion, sustainability as a contributor, and promotion. Finally, what does matter to be promoted? being a good contributor? being a good animator? knowing the boss? We explore this question looking at the process of election for administrator in the English Wikipedia community. We modeled the candidates according to their revisions and/or social attributes. These attributes are used to construct a predictive model of promotion success, based on the candidates's past behavior, computed thanks to a random forest algorithm. Our model combining knowledge contribution variables and social networking variables successfully explain 78% of the results which is better than the former models. It also helps to refine the criterion for election. If the number of knowledge contributions is the most important element, social interactions come close second to explain the election. But being connected with the future peers (the admins) can make the difference between success and failure, making this epistemic community a very social community too

Effect of cyclosporine on hepatic cytosolic estrogen and androgen receptor levels before and after partial hepatectomy

Estrogen and androgen receptors within the liver have been reported to modulate the hepatic regenerative response to partial hepatectomy. Moreover, cyclosporine has several untoward effects that might occur as a consequence of alterations in sex hormone activity. To evaluate these questions the following experiments were performed. Estrogen and androgen receptors in cytosol were quantitated in livers of rats treated with cyclosporine or olive oil vehicle before and after partial hepatectomy or a sham operation. Ornithine decarboxylase activity and thymidine kinase activity were assessed as indices of hepatic regeneration. Preoperative levels of estrogen receptor activity in the hepatic cytosol were significantly greater in rats treated with cyclosporine as compared to vehicle treated controls (P<0.01). In contrast, preoperative levels of androgen receptor activity in the cyclosporine-treated and vehicle-treated animals were similar. Following partial hepatectomy, a reduction in the activity of both sex hormone receptors in the hepatic cytosol was observed and was compatible with results described previously in normal animals. Unexpectedly the preoperative levels of ornithine decarboxylase (P<0.01) and thymidine kinase activity (P<0.01) were significantly greater in the rats treated with cyclosporine as compared to the vehicle treated controls. As expected, ornithine decarboxylase activity (at 6 hr) and thymidine kinase activity (at 24 hr) rose and peaked in response to a partial hepatectomy but were significantly greater (P<0.05) in the rats treated with cyclosporine as compared to the vehicle. These results show that cyclosporine treatment causes an increase in the hepatic content of estrogen receptor activity that is associated with an enhanced potential for a regenerative response. These effects of cyclosporine treatment on the sex hormone receptor levels in liver may explain the mechanisms responsible for some of the untoward effects of treatment with this agent. © 1990 Plenum Publishing Corporation

Physical activity to improve cognition in older adults: can physical activity programs enriched with cognitive challenges enhance the effects? A systematic review and meta-analysis

: EPHPP quality rating scores (DOCX 38 kb

Circular No. 76 - The Utah Agricultural Experiment Station

The Utah Agricultural Experiment Station is one ,of three major divisions of the Agricultural College of Utah, these divisions being: (1) The College proper, (2) the Agricultural Experiment Station, and (3) the Agricultural Extension Service