A discrete MMAP for analysing the behaviour of a multi-state complex dynamic system subject to multiple events.

A complex multi-state system subject to different types of failures, repairable and/or nonrepairable, external shocks and preventive maintenance is modelled by considering a discrete Markovian arrival process with marked arrivals (D-MMAP). The internal performance of the system is composed of several degradation states partitioned into minor and major damage states according to the risk of failure. Random external events can produce failures throughout the system. If an external shock occurs, there may be an aggravation of the internal degradation, cumulative external damage or extreme external failure. The internal performance and the cumulative external damage are observed by random inspection. If major degradation is observed, the unit goes to the repair facility for preventive maintenance. If a repairable failure occurs then the system goes to corrective repair with different time distributions depending on the failure state. Time distributions for corrective repair and preventive maintenance depend on the failure state. Rewards and costs depending on the state at which the device failed or was inspected are introduced. The system is modelled and several measures of interest are built into transient and stationary regimes. A preventive maintenance policy is shown to determine the effectiveness of preventive maintenance and the optimum state of internal and cumulative external damage at which preventive maintenance should be taken into account. A numerical example is presented, revealing the efficacy of the model. Correlations between the numbers of different events over time and in non-overlapping intervals are calculated. The results are expressed in algorithmic-matrix form and are implemented computationally with Matlab.Junta de Andalucía, Spain, under the grant FQM307Ministerio de Economía y Competitividad, España, MTM2017-88708-PEuropean Regional Development Fund (ERDF

Upper-limb botulinum toxin A injection and occupational therapy in children with hemiplegic cerebral palsy identified from a population register: A single-blind, randomized, controlled trial

© 2007 American Academy of Pediatrics. All rights reserved.ObjectivesThe purpose of this work was to assess the effect of botulinum toxin A and occupational therapy compared with occupational therapy alone on body structure, activities participation, and self-perception in a sample of children (aged 3-16 years) with hemiplegic cerebral palsy recruited from a statewide register.Patients and methodsParticipants of this single-blind, randomized, controlled trial identified from a population-based cerebral palsy register received either an individually prescribed and localized injection of botulinum toxin A with 4 sessions of occupational therapy over 4 weeks (intervention) or occupational therapy alone (control). Outcomes were assessed from 2 domains of the World Health Organization International Classification of Functioning, Disability, and Health: body structure (Modified Ashworth Scale and Tardieu Scale) and activities participation (Assessment of Motor and Process Skills, Goal Attainment Scale, Pediatric Evaluation of Disability Inventory, and Pediatric Quality of Life Inventory). Self-perception was also measured.ResultsAll of the participants (intervention: n = 21; control: n = 22) provided data at baseline and 3 and 6 months. Mean age was 8.6 years; 23 were boys and 20 were girls. At 3 months, children allocated to receive the intervention performed significantly better in terms of body structure and activities participation. They reported improvements in self-perception for the global self-worth domain. At 6 months, the differences between the intervention and control groups persisted for the measures of body structure but not for activities participation or self-perception.ConclusionBotulinum toxin A injection combined with a low-intensity occupational therapy program achieves significant improvements in body structure, activity participation, and self-perception.Remo N. Russo, Maria Crotty, Michelle D. Miller, Sonya Murchland, Peter Flett and Eric Haa

Cervical cancer knowledge and barriers and facilitators to screening among women in two rural communities in Guatemala: a qualitative study

Background Approximately 80% of deaths due to cervical cancer occur in low- and middle-income countries. In Guatemala, limited access to effective screening and treatment has resulted in alarmingly high cervical cancer incidence and mortality rates. Despite access to free-of-cost screening, women continue to face significant barriers in obtaining screening for cervical cancer. Methods In-depth interviews (N = 21) were conducted among women in two rural communities in Guatemala. Interviews followed a semi-structured guide to explore knowledge related to cervical cancer and barriers and facilitators to cervical cancer screening. Results Cervical cancer knowledge was variable across sites and across women. Women reported barriers to screening including ancillary costs, control by male partners, poor provider communication and systems-level resource constraints. Facilitators to screening included a desire to know one’s own health status, conversations with other women, including community health workers, and extra-governmental health campaigns. Conclusions Findings speak to the many challenges women face in obtaining screening for cervical cancer in their communities as well as existing facilitators. Future interventions must focus on improving cervical cancer-related knowledge as well as mitigating barriers and leveraging facilitators to promote screening.Medicine, Faculty ofNon UBCReviewedFacultyResearche

The hardness of network design for unsplittable flow with selfish users

Abstract. In this paper we consider the network design for selfish users problem, where we assume the more realistic unsplittable model in which the users can have general demands and each user must choose a single path between its source and its destination. This model is also called atomic (weighted) network congestion game. The problem can be presented as follows: given a network, which edges should be removed to minimize the cost of the worst Nash equilibrium? We consider both computational issues and existential issues (i.e. the power of network design). We give inapproximability results and approximation algorithms for this network design problem. For networks with linear edge latency functions we prove that there is no approximation algorithm for this problem with approximation ratio less then (3+ √ 5)/2 ≈ 2.618 unless P = NP. We also show that for networks with polynomials of degree d edge latency functions there is no approximation algorithm for this problem with approximation ratio less then d Θ(d) unles

On-line load balancing made simple: Greedy strikes back

Abstract. We provide a new simpler approach to the on-line load balancing problem in the case of restricted assignment of temporary weighted tasks. The approach is very general and allows to derive online distributed algorithms whose competitive ratio is characterized by some combinatorial properties of the underlying graph representing the problem. The effectiveness of our approach is shown by the hierarchical server model introduced by Bar-Noy et al ’99. In this case, our method yields simpler and distributed algorithms whose competitive ratio is at least as good as the existing ones. Moreover, the resulting algorithms and their analysis turn out to be simpler. Finally, in all cases the algorithms are optimal up to a constant factor. Some of our results are obtained via a combinatorial characterization of those graphs for which our technique yields O ( √ n)-competitive algorithms.