The Zero-Undetected-Error Capacity Approaches the Sperner Capacity

Ahlswede, Cai, and Zhang proved that, in the noise-free limit, the zero-undetected-error capacity is lower bounded by the Sperner capacity of the channel graph, and they conjectured equality. Here we derive an upper bound that proves the conjecture.Comment: 8 Pages; added a section on the definition of Sperner capacity; accepted for publication in the IEEE Transactions on Information Theor

Message-Cognizant Assistance and Feedback for the Gaussian Channel

A formula is derived for the capacity of the Gaussian channel with a benevolent message-cognizant rate-limited helper that provides a noncausal description of the noise to the encoder and decoder. This capacity is strictly larger than when the helper is message oblivious, with the difference being particularly pronounced at low signal-to-noise ratios. It is shown that in this setup, a feedback link from the receiver to the encoder does not increase capacity. However, in the presence of such a link, said capacity can be achieved even if the helper is oblivious to the transmitted message

Asymmetric Load Balancing on a Heterogeneous Cluster of PCs

In recent years, high performance computing with commodity clusters of personal computers has become an active area of research. Many organizations build them because they need the computational speedup provided by parallel processing but cannot afford to purchase a supercomputer. With commercial supercomputers and homogenous clusters of PCs, applications that can be statically load balanced are done so by assigning equal tasks to each processor. With heterogeneous clusters, the system designers have the option of quickly adding newer hardware that is more powerful than the existing hardware. When this is done, the assignment of equal tasks to each processor results in suboptimal performance. This research addresses techniques by which the size of the tasks assigned to processors is a suitable match to the processors themselves, in which the more powerful processors can do more work, and the less powerful processors perform less work. We find that when the range of processing power is narrow, some benefit can be achieved with asymmetric load balancing. When the range of processing power is broad, dramatic improvements in performance are realized our experiments have shown up to 92% improvement when asymmetrically load balancing a modified version of the NAS Parallel Benchmarks\u27 LU application

An adaptable implementation package targeting evidence-based indicators in primary care: a pragmatic cluster-randomised evaluation

Background In primary care, multiple priorities and system pressures make closing the gap between evidence and practice challenging. Most implementation studies focus on single conditions, limiting generalisability. We compared an adaptable implementation package against an implementation control and assessed effects on adherence to four different evidence-based quality indicators. Methods and findings We undertook two parallel, pragmatic cluster-randomised trials using balanced incomplete block designs in general practices in West Yorkshire, England. We used ‘opt-out’ recruitment, and we randomly assigned practices that did not opt out to an implementation package targeting either diabetes control or risky prescribing (Trial 1); or blood pressure (BP) control or anticoagulation in atrial fibrillation (AF) (Trial 2). Within trials, each arm acted as the implementation control comparison for the other targeted indicator. For example, practices assigned to the diabetes control package acted as the comparison for practices assigned to the risky prescribing package. The implementation package embedded behaviour change techniques within audit and feedback, educational outreach, and computerised support, with content tailored to each indicator. Respective patient-level primary endpoints at 11 months comprised the following: achievement of all recommended levels of haemoglobin A1c (HbA1c), BP, and cholesterol; risky prescribing levels; achievement of recommended BP; and anticoagulation prescribing. Between February and March 2015, we recruited 144 general practices collectively serving over 1 million patients. We stratified computer-generated randomisation by area, list size, and pre-intervention outcome achievement. In April 2015, we randomised 80 practices to Trial 1 (40 per arm) and 64 to Trial 2 (32 per arm). Practices and trial personnel were not blind to allocation. Two practices were lost to follow-up but provided some outcome data. We analysed the intention-to-treat (ITT) population, adjusted for potential confounders at patient level (sex, age) and practice level (list size, locality, pre-intervention achievement against primary outcomes, total quality scores, and levels of patient co-morbidity), and analysed cost-effectiveness. The implementation package reduced risky prescribing (odds ratio [OR] 0.82; 97.5% confidence interval [CI] 0.67–0.99, p = 0.017) with an incremental cost-effectiveness ratio of £1,359 per quality-adjusted life year (QALY), but there was insufficient evidence of effect on other primary endpoints (diabetes control OR 1.03, 97.5% CI 0.89–1.18, p = 0.693; BP control OR 1.05, 97.5% CI 0.96–1.16, p = 0.215; anticoagulation prescribing OR 0.90, 97.5% CI 0.75–1.09, p = 0.214). No statistically significant effects were observed in any secondary outcome except for reduced co-prescription of aspirin and clopidogrel without gastro-protection in patients aged 65 and over (adjusted OR 0.62; 97.5% CI 0.39–0.99; p = 0.021). Main study limitations concern our inability to make any inferences about the relative effects of individual intervention components, given the multifaceted nature of the implementation package, and that the composite endpoint for diabetes control may have been too challenging to achieve. Conclusions In this study, we observed that a multifaceted implementation package was clinically and cost-effective for targeting prescribing behaviours within the control of clinicians but not for more complex behaviours that also required patient engagement. Trial registration The study is registered with the ISRCTN registry (ISRCTN91989345)

The pancreas unmanned ground vehicle

Master of ScienceDepartment of Biological & Agricultural EngineeringDaniel FlippoGlobal agricultural output must increase by 25 to 70% by 2050 to feed the world. The development of more resilient, higher yield crops using genotype to phenotype prediction is one promising method to achieve this growth. Progress in genotype to phenotype models has been constrained by the quantity of hand measurements necessary to accurately describe phenotype characteristics. The Pancreas unmanned ground vehicle was developed to fill this gap in capability. The Pancreas is a four-wheeled unmanned vehicle which carries an electromagnetic inductance sensor to gather soil moisture data throughout the day. This sensor offers a reduction in the time required and an increase in the quantity of measurements taken over the typical soil core methods of measurement. The initial Pancreas prototypes were developed by Dr. Daniel Flippo and master’s student Calvin Dahms. The author made alterations to these designs to reflect a change in operational requirements after the testing results of these prototypes. Broadly, the platform was made more robust, a path following algorithm and new control system were implemented, and a new power budget was developed. Though these changes represent necessary improvements, the platform needs more work and testing to effectively perform its role. Increased power use, sensor accuracy, obstacle detection and avoidance, and durability remain problems to address in future work

A qualitative study exploring the acceptability of the McNulty-Zelen design for randomised controlled trials evaluating educational interventions

Background: Traditional randomised controlled trials evaluating the effect of educational interventions in general practice may produce biased results as participants know they are being evaluated. We aimed to explore the acceptability of a McNulty-Zelen Cluster Randomised Control Trial (CRT) design which conceals from educational participants that they are in a RCT. Consent is obtained from a trusted third party considered appropriate to give consent on participants’ behalf, intervention practice staff then choose whether to attend the offered education as would occur with normal continuing professional development. Methods:We undertook semi structured telephone interviews in England with 16 general practice (GP) staff involved in a RCT evaluating an educational intervention aimed at increasing chlamydia screening tests in general practice using the McNulty-Zelen design, 4 Primary Care (PC) Research Network officers, 5 Primary Care Trust leads in Public or sexual health, and one Research Ethics committee Chair. Interviews were undertaken by members of the original intervention evaluation McNulty-Zelen design RCT study team. These experienced qualitative interviewers used an agreed semi-structured interview schedule and were careful not to lead the participants. To further mitigate against bias, the data analysis was undertaken by a researcher (CR) not involved in the original RCT. Results: We reached data saturation and found five main themes; Support for the design: All found the McNulty-Zelen design acceptable because they considered that it generated more reliable evidence of the value of new educational interventions in real life GP settings. Lack of familiarity with study design: The design was novel to all. GP staff likened the evaluation using the McNulty–Zelen design to audit of their activities with feedback, which were to them a daily experience and therefore acceptable. Ethical considerations:Research stakeholders considered the consent procedure should be very clear and that these trial designs should go through at least a proportionate ethical review. GP staff were happy for the PCT leads to give consent on their behalf. GP research capacity and trial participation: GP staff considered the design increased generalisability, as staff who would not normally volunteer to participate in research due to perceived time constraints and paperwork might do so. Design ‘worth it’: All interviewees agreed that the advantages of the “more accurate” or “truer” results and information gained about uptake of workshops within Primary Care Trusts (PCTs) outweighed any disadvantages of the consent procedure. Discussion:Our RCT was evaluating the effect of an educational intervention to increase chlamydia screening tests in general practices where there was routine monitoring of testing rates; our participants may have been less enthusiastic about the design if it had been evaluating a more controversial educational area, or if data monitoring was not routine. Implications:The McNulty-Zelen design should be considered for the evaluation of educational interventions, but these designs should have clear consent protocols and proportionate ethical review. Trial registration: The trial was registered on the UK Clinical Research Network Study Portfolio database. UKCRN9722

Using GRASP and GA to design resilient and cost-effective IP/MPLS networks

The main objective of this thesis is to find good quality solutions for representative instances of the problem of designing a resilient and low cost IP/MPLS network, to be deployed over an existing optical transport network. This research is motivated by two complementary real-world application cases, which comprise the most important commercial and academic networks of Uruguay. To achieve this goal, we performed an exhaustive analysis of existing models and technologies. From all of them we took elements that were contrasted with the particular requirements of our counterparts. We highlight among these requirements, the need of getting solutions transparently implementable over a heterogeneous network environment, which limit us to use widely standardized features of related technologies. We decided to create new models more suitable to fit these needs. These models are intrinsically hard to solve (NP-Hard). Thus we developed metaheuristic based algorithms to find solutions to these real-world instances. Evolutionary Algorithms and Greedy Randomized Adaptive Search Procedures obtained the best results. As it usually happens, real-world planning problems are surrounded by uncertainty. Therefore, we have worked closely with our counterparts to reduce the fuzziness upon data to a set of representative cases. They were combined with different strategies of design to get to scenarios, which were translated into instances of these problems. Finally, the algorithms were fed with this information, and from their outcome we derived our results and conclusions