Stuttering equivalence is too slow!

Groote and Wijs recently described an algorithm for deciding stuttering equivalence and branching bisimulation equivalence, acclaimed to run in $\mathcal{O}(m \log n)$ time. Unfortunately, the algorithm does not always meet the acclaimed running time. In this paper, we present two counterexamples where the algorithms uses $\Omega(md)$ time. A third example shows that the correction is not trivial. In order to analyse the problem we present pseudocode of the algorithm, and indicate the time that can be spent on each part of the algorithm in order to meet the desired bound. We also propose fixes to the algorithm such that it indeed runs in $\mathcal{O}(m \log n)$ time.Comment: 11 page

Defining the end of new wars

New wars are defined by their innate disposition to blur distinctions and human rights violations while structurally undermining the enjoyment of human rights. These wars are self-fueling human rights cataclysms that destroy society and its social contract by blurring the distinction between government, army and people. These characteristics prolong into what is perceived as post-conflict and blur the distinction between war and peace. The lack of acknowledgment and understanding of these characteristics among the actors who provide relief and seek resolution to the conflict undermines the effectiveness of their actions and the coordination among them resulting in aid gaps. The human rights canon is constantly used and abused in the hodgepodge of activities deployed in early recovery. The omnipotent presence of human rights in the new war context justifies using the human rights canon to define the end of a new war. Legal concepts within international law and the specific characteristics of new wars provide the human rights that are applicable in the new war context and define the end of a new war. Providing a definition for the end of a new war is conducive to consensus among those involved on whether a state is in a phase of conflict, postconflict, peace or development. Additionally, this research assists in understanding the new war context. Such consensus on and increased understanding of the context contributes to diminishing aid gaps by improving cooperation and coordination

Viscosity of Water in Nano-Confinement

Since the early 1970s there is a notion that water near polar or charged surfaces is somehow ordered or structured, leading to a so called structural component of the disjoining pressure

Chiral gauge theories with domain wall fermions

We have investigated a proposal to construct chiral gauge theories on the lattice using domain wall fermions. The model contains two opposite chirality zeromodes, which live on two domain walls. We couple only one of them to a gauge field, but find that mirror fermions which also couple to the gauge field always seem to exist.Comment: 3 pages. ref. added, some rewording at the end. contribution to Lattice'93. latex file, style file espcrc2.sty needed (appended), compressed tar file with two figures appended at the end (look for FIGURES

Capillarity effect in silicon based nanochannels

Using silicon based micromachining we have developed different techniques to create 1D and 2D confined nanochannels, with a characteristic diameter down to 5 nm. A short introduction to these techniques will be given. Capillary action in channels of this small size is a strong effect

Cost-Effectiveness Evaluation of Etoricoxib versus Celecoxib and Nonselective NSAIDs in the Treatment of Ankylosing Spondylitis in Norway

Objectives. To evaluate the cost-effectiveness of etoricoxib (90 mg) relative to celecoxib (200/400 mg), and the nonselective NSAIDs naproxen (1000 mg) and diclofenac (150 mg) in the initial treatment of ankylosing spondylitis in Norway. Methods. A previously developed Markov state-transition model was used to estimate costs and benefits associated with initiating treatment with the different competing NSAIDs. Efficacy, gastrointestinal and cardiovascular safety, and resource use data were obtained from the literature. Data from different studies were synthesized and translated into direct costs and quality adjusted life years by means of a Bayesian comprehensive decision modeling approach. Results. Over a 30-year time horizon, etoricoxib is associated with about 0.4 more quality adjusted life years than the other interventions. At 1 year, naproxen is the most cost-saving strategy. However, etoricoxib is cost and quality adjusted life year saving relative to celecoxib, as well as diclofenac and naproxen after 5 years of follow-up. For a willingness-to-pay ceiling ratio of 200,000 Norwegian krones per quality adjusted life year, there is a >95% probability that etoricoxib is the most-cost-effective treatment when a time horizon of 5 or more years is considered. Conclusions. Etoricoxib is the most cost-effective NSAID for initiating treatment of ankylosing spondylitis in Norway

Editorial–data analysis in metabolomics

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Network Meta-analysis on Disconnected Evidence Networks When Only Aggregate Data Are Available:Modified Methods to Include Disconnected Trials and Single-Arm Studies while Minimizing Bias

BACKGROUND: Network meta-analysis (NMA) requires a connected network of randomized controlled trials (RCTs) and cannot include single-arm studies. Regulators or academics often have only aggregate data. Two aggregate data methods for analyzing disconnected networks are random effects on baseline and aggregate-level matching (ALM). ALM has been used only for single-arm studies, and both methods may bias effect estimates. METHODS: We modified random effects on baseline to separate RCTs connected to and disconnected from the reference and any single-arm studies, minimizing the introduction of bias. We term our modified method reference prediction. We similarly modified ALM and extended it to include RCTs disconnected from the reference. We tested these methods using constructed data and a simulation study. RESULTS: In simulations, bias for connected treatments for ALM ranged from −0.0158 to 0.051 and for reference prediction from −0.0107 to 0.083. These were low compared with the true mean effect of 0.5. Coverage ranged from 0.92 to 1.00. In disconnected treatments, bias of ALM ranged from −0.16 to 0.392 and of reference prediction from −0.102 to 0.40, whereas coverage of ALM ranged from 0.30 to 0.82 and of reference prediction from 0.64 to 0.94. Under fixed study effects for disconnected evidence, bias was similar, but coverage was 0.81 to 1.00 for reference prediction and 0.18 to 0.76 for ALM. Trends of similar bias but greater coverage for reference prediction with random study effects were repeated in constructed data. CONCLUSIONS: Both methods with random study effects seem to minimize bias in treatment connected to the reference. They can estimate treatment effects for disconnected treatments but may be biased. Reference prediction has greater coverage and may be recommended overall. HIGHLIGHTS: Two methods were modified for network meta-analysis on disconnected networks and for including single-arm observational or interventional studies in network meta-analysis using only aggregate data and for minimizing the bias of effect estimates for treatments only in trials connected to the reference. Reference prediction was developed as a modification of random effects on baseline that keeps analyses of trials connected to the reference separately from those disconnected from the reference and from single-arm studies. The method was further modified to account for correlation in trials with more than 2 arms and, under random study effects, to estimate variance in heterogeneity separately in connected and disconnected evidence. Aggregate-level matching was extended to include trials disconnected from the reference, rather than only single-arm studies. The method was further modified to separately estimate treatment effects and heterogeneity variance in the connected and disconnected evidence and to account for the correlation between arms in trials with more than 2 arms. Performance was assessed using a constructed data example and simulation study. The methods were found to have similar, and sometimes low, bias when estimating the relative effects for disconnected treatments, but reference prediction with random study effects had the greatest coverage. The use of reference prediction with random study effects for disconnected networks is recommended if no individual patient data or alternative real-world evidence is available