Late Cenozoic tephrostratigraphy offshore the southern Central American Volcanic Arc: 2. Implications for magma production rates and subduction erosion

Pacific drill sites offshore Central America provide the unique opportunity to study the evolution of large explosive volcanism and the geotectonic evolution of the continental margin back into the Neogene. The temporal distribution of tephra layers established by tephrochonostratigraphy in Part 1 indicates a nearly continuous highly explosive eruption record for the Costa Rican and the Nicaraguan volcanic arc within the last 8 M.y. The widely distributed marine tephra layers comprise the major fraction of the respective erupted tephra volumes and masses thus providing insights into regional and temporal variations of large-magnitude explosive eruptions along the southern Central American Volcanic Arc (CAVA). We observe three pulses of enhanced explosive magmatism between 0-1 Ma at the Cordillera Central, between 1-2 Ma at the Guanacaste and at >3 Ma at the Western Nicaragua segments. Averaged over the long-term the minimum erupted magma flux (per unit arc length) is ∼0.017 g/ms. Tephra ages, constrained by Ar-Ar dating and by correlation with dated terrestrial tephras, yield time-variable accumulation rates of the intercalated pelagic sediments with four prominent phases of peak sedimentation rates that relate to tectonic processes of subduction erosion. The peak rate at >2.3 Ma near Osa particularly relates to initial Cocos Ridge subduction which began at 2.91±0.23 Ma as inferred by the 1.5 M.y. delayed appearance of the OIB geochemical signal in tephras from Barva volcano at 1.42 Ma. Subsequent tectonic re-arrangements probably involved crustal extension on the Guanacaste segment that favored the 2-1 Ma period of unusually massive rhyolite production

Costs and Effects of Abdominal versus Laparoscopic Hysterectomy: Systematic Review of Controlled Trials

Objective: Comparative evaluation of costs and effects of laparoscopic hysterectomy (LH) and abdominal hysterectomy (AH). Data sources: Controlled trials from Cochrane Central register of controlled trials, Medline, Embase and prospective trial registers. Selection of studies: Twelve (randomized) controlled studies including the search terms costs, laparoscopy, laparotomy and hysterectomy were identified. Methods: The type of cost analysis, perspective of cost analyses and separate cost components were assessed. The direct and indirect costs were extracted from the original studies. For the cost estimation, hospital stay and procedure costs were selected as most important cost drivers. As main outcome the major complication rate was taken. Findings: Analysis was performed on 2226 patients, of which 1013 (45.5%) in the LH group and 1213 (54.5%) in the AH group. Five studies scored >= 10 points (out of 19) for methodological quality. The reported total direct costs in the LH group ($63,997) were 6.1$60,114). The reported total indirect costs of the LH group ($1,609) were half of the total indirect in the AH group ($3,139). The estimated mean major complication rate in the LH group (14.3%) was lower than in the AH group (15.9%). The estimated total costs in the LH group were $3,884 versus$3,312 in the AH group. The incremental costs for reducing one patient with major complication(s) in the LH group compared to the AH group was $35,750. Conclusions: The shorter hospital stay in the LH group compensates for the increased procedure costs, with less morbidity. LH points in the direction of cost effectiveness, however further research is warranted with a broader costs perspective including long term effects as societal benefit, quality of life and survival

Laparoscopic versus conventional appendectomy - a meta-analysis of randomized controlled trials

<p>Abstract</p> <p>Background</p> <p>Although laparoscopic surgery has been available for a long time and laparoscopic cholecystectomy has been performed universally, it is still not clear whether open appendectomy (OA) or laparoscopic appendectomy (LA) is the most appropriate surgical approach to acute appendicitis. The purpose of this work is to compare the therapeutic effects and safety of laparoscopic and conventional "open" appendectomy by means of a meta-analysis.</p> <p>Methods</p> <p>A meta-analysis was performed of all randomized controlled trials published in English that compared LA and OA in adults and children between 1990 and 2009. Calculations were made of the effect sizes of: operating time, postoperative length of hospital stay, postoperative pain, return to normal activity, resumption of diet, complications rates, and conversion to open surgery. The effect sizes were then pooled by a fixed or random-effects model.</p> <p>Results</p> <p>Forty-four randomized controlled trials with 5292 patients were included in the meta-analysis. Operating time was 12.35 min longer for LA (95% CI: 7.99 to 16.72, p < 0.00001). Hospital stay after LA was 0.60 days shorter (95% CI: -0.85 to -0.36, p < 0.00001). Patients returned to their normal activity 4.52 days earlier after LA (95% CI: -5.95 to -3.10, p < 0.00001), and resumed their diet 0.34 days earlier(95% CI: -0.46 to -0.21, p < 0.00001). Pain after LA on the first postoperative day was significantly less (p = 0.008). The overall conversion rate from LA to OA was 9.51%. With regard to the rate of complications, wound infection after LA was definitely reduced (OR = 0.45, 95% CI: 0.34 to 0.59, p < 0.00001), while postoperative ileus was not significantly reduced(OR = 0.91, 95% CI: 0.57 to 1.47, p = 0.71). However, intra-abdominal abscess (IAA), intraoperative bleeding and urinary tract infection (UIT) after LA, occurred slightly more frequently(OR = 1.56, 95% CI: 1.01 to 2.43, p = 0.05; OR = 1.56, 95% CI: 0.54 to 4.48, p = 0.41; OR = 1.76, 95% CI: 0.58 to 5.29, p = 0.32).</p> <p>Conclusion</p> <p>LA provides considerable benefits over OA, including a shorter length of hospital stay, less postoperative pain, earlier postoperative recovery, and a lower complication rate. Furthermore, over the study period it was obvious that there had been a trend toward fewer differences in operating time for the two procedures. Although LA was associated with a slight increase in the incidence of IAA, intraoperative bleeding and UIT, it is a safe procedure. It may be that the widespread use of LA is due to its better therapeutic effect.</p

Optimisation d'hypertextes par algorithmes biomimétiques

In this technique, some documents like HTML are used as entering data. The purpose of this technique is to optimize links between these documents and to build a hypertexte system which can be used by users for searching information. To achieve this goal, the following two methods have been studied. The first method uses the principles of genetic algorithms for optimizing a matrix of links and for maximizing the fitness function This function measures the correlation between two variables : the thematic distance between documents and distance between nodes in the hypertexte. The second method is based on maps of documents which can organize the documents in clusters according to the similarity between them, and which may present these clusters in a visual way. It makes use of 2d cellular automata. Each cell of automata is to visually present similar documents in neighbouring cells. The resulting map can be used by the user to open the documents by the click on the corresponding cell.Dans ce travail nous considérons des documents HTML des données d'entrée. Notre objectif est d'optimiser des liens entre ces documents et de construire un hypertexte grâce auquel l'utilisateur peut naviguer facilement pour chercher des informations. Pour arriver à cet objectif, nous avons proposé deux méthodes. Une méthode qui utilise un algorithme génétique pour optimiser une matrice de liens de manière à maximiser une fonction de qualité. Cette fonction vise à mesurer une corrélation entre les distances thématiques entre les documents et les distances entre les noeuds du graphe reliant ces documents entre eux (des documents proches thématiquement doivent être séparés par un nombre faible de clics sur des hyperliens). La deuxième méthode est une carte de documents qui va regrouper les documents en classes selon leur similarité et proposer un résultat virtuel, en utilisant un automate cellulaire 2D. Chaque cellule de la grille prend des états égaux à vide ou à l'un des documents. L'objectif de l'automate est de faire apparaître des états voisins thématiquement sur des cellules voisines de la grilles. Les résultats forment ainsi une carte cliquable qui se comporte comme un hypertexte.TOURS-BU Sciences Pharmacie (372612104) / SudocTOURS-Polytech'Informat.Product. (372612209) / SudocSudocFranceF