2,462 research outputs found

    Multiple paths through a network

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    The most sophisticated iterative algorithm for balancing network congestion for a given set of desired vehicle movement from origins to destinations can generate thousands of paths of equal cost to connect a single O-D pair. Some sets of paths are combinations of minor variations on one main path, while other sets contain various degrees of difference, possibly up to complete independence. Present methods for comparing paths do not take into account the multi-dimensional nature of similarities and differences between paths, or the different character of sets of paths - especially from a geographic point of view. I develop a battery of methods of making comparisons, and apply them to illustrative sets of paths identified in the highly disaggregated Chicago network. I begin a discussion of how these comparisons might be used to throw light on problems of network aggregation and of discrete choice of route among populations of users.

    Economic Aspects of the Metropolitan Region

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    Economic Aspects of the Metropolitan Region

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    Algorithmic and technical improvements: Optimal solutions to the (Generalized) Multi-Weber Problem

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    Rosing has recently demonstrated a new method for obtaining optimal solutions to the (Generalized) Multi-Weber Problem and proved the optimality of the results. The method develops all convex hulls and then covers the destinations with disjoint convex hulls. This paper seeks to improve implementation of the algorithm to make such solutions economically attractive. Four areas are considered: sharper decision rules to eliminate unnecessary searching, bit pattern matching as a method of recording a history and eliminating duplication, vector intrinsic functions to speed up comparisons, and profiling a program to maximize operating efficiency. Computational experience is also presented

    An exploratory randomized controlled trial of assisted practice for improving sit-to-stand in stroke patients in the hospital setting

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    Objectives: To evaluate the amount of practice achieved and assess potential for effects on performance of 30 minutes of daily training in sit-to-stand. Design: Randomized controlled pilot study. Setting: Stroke rehabilitation unit, UK. Participants: Eighteen stroke patients needing 'stand by' help to sit-to-stand. Interventions: In addition to usual rehabilitation the experimental group (n=9) practised sit-to-stand and leg strengthening exercises for 30 minutes, on weekdays for two weeks, with a physiotherapy assistant. The control group received arm therapy. Main outcome measures: Frequency of sit-to-stands per day. Performance measures: rise time, weight taken through the affected foot at 'thighs off', number of attempts needed to achieve three successful sit-to-stands and the number of sit-to-stands performed in 60 seconds. Outcome was measured one and two weeks after baseline assessment. Results: Sit-to-stand frequency averaged 18 per day. Thirty minutes of practice in sit-to-stand resulted in a mean of 50 (SD 17.2) extra stands per day. There was a significant mean difference of 10% body weight taken through the affected foot after one week of intervention: The control group had reduced weight through the affected leg while the training group increased weight (F1,16 = 11.1, P=0.004, 95% confidence interval (CI) - 16.61 to - 3.72). No significant differences between groups were found on other measures. Results two weeks after baseline were inconclusive due to loss of five participants. Conclusions: Task-specific practice given for 30 minutes a day appears promising for patients learning to sit-to-stand. © SAGE Publications 2008

    Spatial and spatio-temporal patterns in a cell-haptotaxis model

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    We investigate a cell-haptotaxis model for the generation of spatial and spatio-temporal patterns in one dimension. We analyse the steady state problem for specific boundary conditions and show the existence of spatially hetero-geneous steady states. A linear analysis shows that stability is lost through a Hopf bifurcation. We carry out a nonlinear multi-time scale perturbation procedure to study the evolution of the resulting spatio-temporal patterns. We also analyse the model in a parameter domain wherein it exhibits a singular dispersion relation

    Genome-wide DNA methylation profiling confirms a case of low-level mosaic Kabuki syndrome 1

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    Kabuki syndrome is a Mendelian disorder of the epigenetic machinery characterized by typical dysmorphic features, intellectual disability, and postnatal growth deficiency. Pathogenic variants in the genes encoding the chromatin modifiers KMT2D and KDM6A are responsible for Kabuki syndrome 1 (KS1) and Kabuki syndrome 2 (KS2), respectively. In addition, 11 cases of KS1 caused by mosaic variants in KMT2D have been reported in the literature. Some of these individuals display milder craniofacial and growth phenotypes, and most do not have congenital heart defects. We report the case of an infant with severe hypoplastic left heart syndrome with mitral atresia and aortic atresia (HLHS MA-AA), pulmonary vein stenosis, and atypical facies with a somatic mosaic de novo nonsense variant in KMT2D (c.8200C\u3eT, p.R2734*) identified on trio exome sequencing of peripheral blood and present in 11.2% of sequencing reads. KS was confirmed with EpiSign, a diagnostic genome-wide DNA methylation platform used to identify epigenetic signatures. This case suggests that use of this newly available clinical test can guide the interpretation of low-level mosaic variants identified through sequencing and suggests a new lower limit of mosaicism in whole blood required for a diagnosis of KS
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