Meta-Modeling by Symbolic Regression and Pareto Simulated Annealing

The subject of this paper is a new approach to Symbolic Regression.Other publications on Symbolic Regression use Genetic Programming.This paper describes an alternative method based on Pareto Simulated Annealing.Our method is based on linear regression for the estimation of constants.Interval arithmetic is applied to ensure the consistency of a model.In order to prevent over-fitting, we merit a model not only on predictions in the data points, but also on the complexity of a model.For the complexity we introduce a new measure.We compare our new method with the Kriging meta-model and against a Symbolic Regression meta-model based on Genetic Programming.We conclude that Pareto Simulated Annealing based Symbolic Regression is very competitive compared to the other meta-model approachesapproximation;meta-modeling;pareto simulated annealing;symbolic regression

Fast Ejection Chain Algorithms for Vehicle Routing with Time Windows

This paper introduces new ejection chain strategies to effectively target vehicle routing problems with time window constraints (VRPTW). Ejection chain procedures are based on the idea of compound moves that allow a variable number of solution components to be modified within any single iteration of a local search algorithm. The yardstick behind such procedures is the underlying reference structure, which is the structure that is used to coordinate the moves that are available for the local search algorithm. The main contribution of the paper is a new reference structure that is particularly suited in order to handle the asymmetric aspects in a VRPTW. The new reference structure is a generalization of the doubly rooted reference structure introduced by Glover, resulting in a new, powerful neighborhood for the VRPTW. We use tabu search for the generation of the ejection chains. On a higher algorithmic level, we study the effect of different meta heuristics to steer the tabu chain ejection process. Computational results confirm that our approach leads to very fast algorithms that can compete with the current state of the art algorithms for the VRPTW.operations research and management science;

Meta-Modeling by Symbolic Regression and Pareto Simulated Annealing

The subject of this paper is a new approach to Symbolic Regression.Other publications on Symbolic Regression use Genetic Programming.This paper describes an alternative method based on Pareto Simulated Annealing.Our method is based on linear regression for the estimation of constants.Interval arithmetic is applied to ensure the consistency of a model.In order to prevent over-fitting, we merit a model not only on predictions in the data points, but also on the complexity of a model.For the complexity we introduce a new measure.We compare our new method with the Kriging meta-model and against a Symbolic Regression meta-model based on Genetic Programming.We conclude that Pareto Simulated Annealing based Symbolic Regression is very competitive compared to the other meta-model approaches

Koper in levers van Nederlandse mestkalveren

Naar aanleiding van een in 1983/1984 door het RIKILT uitgevoerd onderzoek werd een vervolgonderzoek uitgevoerd naar de kopergehalten in levers van mestkalveren. In verband met een mogelijke interactie werden tevens de ijzer - , zink- en mangaangehalten in kalfslevers bepaald. Daarnaast werden levers van pas geboren kalveren en kunstmelkpoeders van 26 verschillende fabrikanten onderzocht

Impact of ultra-thin struts on restenosis after chronic total occlusion recanalization: Insights from the randomized PRISON IV trial

The PRISON-IV trial showed inferior outcome in patients with chronic total occlusions (CTOs) treated with the ultrathin-struts (60\u2009\u3bcm for stent diameter 643\u2009mm, 81\u3bcm >3\u2009mm) hybrid-sirolimus eluting stents (SES) compared with everolimus eluting stents (EES, 81\u2009\u3bcm). The aim of this study is to investigate if the use of smaller stents ( 643\u2009mm) was responsible for the inferior outcome reported in the trial

De bepaling van calcium en fosfor in melk met behulp van ICP-AES

Een methode, gebaseerd op een monstervoorbewerking met trichloorazijnzuur en meting met behulp van ICP-AES, werd uitgetest voor de bepaling van Ca en P in melk. De resultaten van deze methode werden vergeleken met de resultaten, welke door de afdeling Algemene Chemie met behulp van fotometrische technieken werden verkregen

Predictive Value of POSSUM and ACPGBI Scoring in Mortality and Morbidity of Colorectal Resection: A Case–Control Study

Contains fulltext : 97239.pdf (publisher's version ) (Open Access)BACKGROUND: Preoperative risk prediction to assess mortality and morbidity may be helpful to surgical decision making. The aim of this study was to compare mortality and morbidity of colorectal resections performed in a tertiary referral center with mortality and morbidity as predicted with physiological and operative score for enumeration of mortality and morbidity (POSSUM), Portsmouth POSSUM (P-POSSUM), and colorectal POSSUM (CR-POSSUM). The second aim of this study was to analyze the accuracy of different POSSUM scores in surgery performed for malignancy, inflammatory bowel diseases, and diverticulitis. POSSUM scoring was also evaluated in colorectal resection in acute vs. elective setting. In procedures performed for malignancy, the Association of Coloproctology of Great Britain and Ireland (ACPGBI) score was assessed in the same way for comparison. METHODS: POSSUM, P-POSSUM, and CR-POSSUM predictor equations for mortality were applied in a retrospective case-control study to 734 patients who had undergone colorectal resection. The total group was assessed first. Second, the predictive value of outcome after surgery was assessed for malignancy (n = 386), inflammatory bowel diseases (n = 113), diverticulitis (n = 91), and other indications, e.g., trauma, endometriosis, volvulus, or ischemia (n = 144). Third, all subgroups were assessed in relation to the setting in which surgery was performed: acute or elective. In patients with malignancy, the ACPGBI score was calculated as well. In all groups, receiver operating characteristic (ROC) curves were constructed. RESULTS: POSSUM, P-POSSUM, and CR-POSSUM have a significant predictive value for outcome after colorectal surgery. Within the total population as well as in all four subgroups, there is no difference in the area under the curve between the POSSUM, P-POSSUM, and CR-POSSUM scores. In the subgroup analysis, smallest areas under the ROC curve are seen in operations performed for malignancy, which is significantly worse than for diverticulitis and in operations performed for other indications. For elective procedures, P-POSSUM and CR-POSSUM predict outcome significantly worse in patients operated for carcinoma than in patients with diverticulitis. In acute surgical interventions, CR-POSSUM predicts mortality better in diverticulitis than in patients operated for other indications. The ACPGBI score has a larger area under the curve than any of the POSSUM scores. Morbidity as predicted by POSSUM is most accurate in procedures for diverticulitis and worst when the indication is malignancy. CONCLUSION: The POSSUM scores predict outcome significantly better than can be expected by chance alone. Regarding the indication for surgery, each POSSUM score predicts outcome in patients operated for diverticulitis or other indications more accurately than for malignancy. The ACPGBI score is found to be superior to the various POSSUM scores in patients who have (elective) resection of colorectal malignancy

Gehalten aan lood, cadmium en kwik in monsters vlees en organen van runderen, varkens, schapen en pluimvee, bemonsterd in 1983 en vergeleken met resultaten over voorgaande jaren

In het kader van het LAC-signaleringsprogramma VREK zijn de analyseresultaten voor lood, cadmium en kwik van monsters vlees, levers en nieren van runderen, varkens en schapen en van monsters vlees en levers van kippen, genomen in 1983, geëvalueerd en vergeleken met resultaten verkregen in voorgaande jaren. De gevonden gehalten zijn getoetst aan de in 1983 geldende aktiegrenzen en richtnormen. De relaties tussen de afzonderlijke metaalgehalten van nieren en levers van de verschillende diersoorten zijn bestudeerd

Gehalten aan cadmium, lood, koper, ijzer en zink in monsters vlees, levers en nieren van kalveren, bemonsterd in 1983

In het kader van het VREK-programma is, als vervolg op een in 1982 verricht onderzoek, een aanvullend onderzoek uitgevoerd naar de looden cadmiumgehal ten in vlees en organen van kalveren. Tevens zijn de koper-, ijzer- en zinkgehalten van deze monsters bepaald om na te gaan of er een relatie bestaat tussen deze elementen en de lood- en cadmiumopname. De gevonden metaalgehalten zijn vergeleken met de resultaten van het in 1982 uitgevoerde onderzoek en met enkele gegevens uit de literatuur. De gevonden lood- en cadmiumgehalten zijn getoetst aan de in 1983 geldende aktiegrenzen en richtnormen voor vlees, levers en nieren van runderen