On-demand Strategy Research Articles

Valutazione economica della terapia di mantenimento al bisogno con esomeprazolo nella malattia da reflusso gastroesofageo

Objective Gastro-esophageal reflux disease (GERD) is a common medical problem with a broad spectrum of symptoms and varying degrees of severity and frequency. Most patients with GERD, regardless of endoscopic status, suffer symptomatic relapses within few months from stopping acid suppressant therapy, thus requiring long term management of their disease to prevent relapses. On-demand therapy (i.e., medication taken as needed to relieve symptoms) might be an effective modality of long-term treatment in patients with non-erosive gastro-esophageal reflux disease. An economic evaluation, the ONE (ON-demand treatment with Esomeprazole) study, was conducted to assess costs and consequences over a 6-month period with the 20 mg esomeprazole on-demand strategy compared to the 20 mg once daily continuous therapy in patients with GERD.

On-demand Evaluation for Maude

Strategy annotations provide a simple mechanism for introducing some laziness in the evaluation of expressions. As an eager programming language, Maude can take advantage of them and, in fact, they are part of the language. Maude strategy annotations are lists of non-negative integers associated to function symbols which specify the ordering in which the arguments are (eventually) evaluated in function calls. A positive index enables the evaluation of an argument whereas 'zero' means that the function call has to be attempted. The use of negative indices has been proposed to express evaluation on-demand, where the demand is an attempt to match an argument term with the left-hand side of a rewrite rule. In this paper we show how to furnish Maude with the ability of dealing with on-demand strategy annotations.

On-demand Evaluation by Program Transformation

Strategy annotations are used in eager programming languages (e.g., OBJ2, OBJ3, CafeOBJ, and Maude) for improving efficiency and/or reducing the risk of nontermination. Syntactically, they are given either as lists of natural numbers or as lists of integers associated to function symbols whose (absolute) values refer to the arguments of the corresponding symbol. A positive index forces the evaluation of an argument whereas a negative index means “evaluation on-demand”. Recently, we have introduced a formal description of the operational meaning of such on-demand strategy annotations which improves previous formalizations that were lacking satisfactory computational properties. In this paper, we introduce an automatic, semantics-preserving program transformation which produces a program (without negative annotations) which can be then correctly executed by typical OBJ interpreters. Moreover, to demonstrate the practicality of our ideas, the program transformation has been implemented (in Haskell) and we compare the evaluation of transformed programs with the original ones on a set of representative benchmarks.

Meta-analysis of relaparotomy for secondary peritonitis.

Planned relaparotomy and relaparotomy on demand are two frequently employed surgical treatment strategies for patients with abdominal sepsis. The available literature was evaluated to compare the efficacy of both surgical treatment strategies. A systematic search for studies comparing planned and on-demand relaparotomy strategies in adult patients with secondary peritonitis was employed. Studies were reviewed independently for design features, inclusion and exclusion criteria, and outcomes. The primary outcome measure was in-hospital mortality. No randomized studies were found; eight observational studies with a total of 1266 patients (planned relaparotomy, 286; relaparotomy on demand, 980) met the inclusion criteria and were included in the meta-analysis. These eight studies were heterogeneous on clinical and statistical grounds (chi2= 40.7, d.f. = 7, P < 0.001). Using a random-effects approach, the combined odds ratio for in-hospital mortality was 0.70 (95 per cent confidence interval 0.27 to 1.80) in favour of the on-demand strategy. The combined results of observational studies show a statistically non-significant reduction in mortality for the on-demand relaparotomy strategy compared with the planned relaparotomy strategy when corrected for heterogeneity in a random-effects model. Owing to the non-randomized nature of the studies, the limited number of patients per study, and the heterogeneity between studies, the overall evidence generated by the eight studies was inconclusive.