A Population-Based Method with Selection of a Search Operator

Author(s):  
Krystian Łapa ◽  
Krzysztof Cpałka ◽  
Tacjana Niksa-Rynkiewicz ◽  
Lipo Wang

Metabolomics ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
João Fadista ◽  
Line Skotte ◽  
Julie Courraud ◽  
Frank Geller ◽  
Sanne Gørtz ◽  
...  

Abstract Introduction Infantile hypertrophic pyloric stenosis (IHPS) is caused by hypertrophy of the pyloric sphincter muscle. Objectives Since previous reports have implicated lipid metabolism, we aimed to (1) investigate associations between IHPS and a wide array of lipid-related metabolites in newborns, and (2) address whether detected differences in metabolite levels were likely to be driven by genetic differences between IHPS cases and controls or by differences in early life feeding patterns. Methods We used population-based random selection of IHPS cases and controls born in Denmark between 1997 and 2014. We randomly took dried blood spots of newborns from 267 pairs of IHPS cases and controls matched by sex and day of birth. We used a mixed-effects linear regression model to evaluate associations between 148 metabolites and IHPS in a matched case–control design. Results The phosphatidylcholine PC(38:4) showed significantly lower levels in IHPS cases (P = 4.68 × 10−8) as did six other correlated metabolites (four phosphatidylcholines, acylcarnitine AC(2:0), and histidine). Associations were driven by 98 case–control pairs born before 2009, when median age at sampling was 6 days. No association was seen in 169 pairs born in 2009 or later, when median age at sampling was 2 days. More IHPS cases than controls had a diagnosis for neonatal difficulty in feeding at breast (P = 6.15 × 10−3). Genetic variants known to be associated with PC(38:4) levels did not associate with IHPS. Conclusions We detected lower levels of certain metabolites in IHPS, possibly reflecting different feeding patterns in the first days of life.



2018 ◽  
Vol 15 (2) ◽  
pp. 254-272 ◽  
Author(s):  
Umamaheswari Elango ◽  
Ganesan Sivarajan ◽  
Abirami Manoharan ◽  
Subramanian Srikrishna

Purpose Generator maintenance scheduling (GMS) is an essential task for electric power utilities as the periodical maintenance activity enhances the lifetime and also ensures the reliable and continuous operation of generating units. Though numerous meta-heuristic algorithms have been reported for the GMS solution, enhancing the existing techniques or developing new optimization procedure is still an interesting research task. The meta-heuristic algorithms are population based and the selection of their algorithmic parameters influences the quality of the solution. This paper aims to propose statistical tests guided meta-heuristic algorithm for solving the GMS problems. Design/methodology/approach The intricacy characteristics of the GMS problem in power systems necessitate an efficient and robust optimization tool. Though several meta-heuristic algorithms have been applied to solve the chosen power system operational problem, tuning of their control parameters is a protracting process. To prevail over the previously mentioned drawback, the modern meta-heuristic algorithm, namely, ant lion optimizer (ALO), is chosen as the optimization tool for solving the GMS problem. Findings The meta-heuristic algorithms are population based and require proper selection of algorithmic parameters. In this work, the ANOVA (analysis of variance) tool is proposed for selecting the most feasible decisive parameters in algorithm domain, and the statistical tests-based validation of solution quality is described. The parametric and non-parametric statistical tests are also performed to validate the selection of ALO against the various competing algorithms. The numerical and statistical results confirm that ALO is a promising tool for solving the GMS problems. Originality/value As a first attempt, ALO is applied to solve the GMS problem. Moreover, the ANOVA-based parameter selection is proposed and the statistical tests such as Wilcoxon signed rank and one-way ANOVA are conducted to validate the applicability of the intended optimization tool. The contribution of the paper can be summarized in two folds: the ANOVA-based ALO for GMS applications and statistical tests-based performance evaluation of intended algorithm.





Author(s):  
Duc-Truong Pham ◽  
Maria M. Suarez-Alvarez ◽  
Yuriy I. Prostov

A new algorithm to cluster datasets with mixed numerical and categorical values is presented. The algorithm, called RANKPRO (random search with k -prototypes algorithm), combines the advantages of a recently introduced population-based optimization algorithm called the bees algorithm (BA) and k -prototypes algorithm. The BA works with elite and good solutions, and continues to look for other possible extrema solutions keeping the number of testing points constant. However, the improvement of promising solutions by the BA may be time-consuming because it is based on random neighbourhood search. On the other hand, an application of the k -prototypes algorithm to a promising solution may be very effective because it improves the solution at each iteration. The RANKPRO algorithm balances two objectives: it explores the search space effectively owing to random selection of new solutions, and improves promising solutions fast owing to employment of the k -prototypes algorithm. The efficiency of the new algorithm is demonstrated by clustering several datasets. It is shown that in the majority of the considered datasets when the average number of iterations that the k -prototypes algorithm needs to converge is over 10, the RANKPRO algorithm is more efficient than the k -prototypes algorithm.



2018 ◽  
Vol 36 (6_suppl) ◽  
pp. 457-457
Author(s):  
Nima Almassi ◽  
Tianming Gao ◽  
Byron Lee ◽  
Robert Stein ◽  
Georges-Pascal Haber ◽  
...  

457 Background: Neoadjuvant chemotherapy (NAC) is infrequently administered to patients with upper tract urothelial carcinoma (UTUC) undergoing radical nephroureterectomy or segmental ureterectomy and its impact on pathologic outcomes unclear. We examine pathologic outcomes in patients with UTUC receiving NAC before extirpative surgery using a population-based cancer registry. Methods: Patients who underwent extirpative surgery for UTUC from 2006-2014 were identified from the National Cancer Database. Among patients with available clinicopathologic data, the incidence of pathologic down-staging, defined as a lesser pathologic compared to clinical stage, was compared between patients who did and did not receive NAC. A multivariable model was developed to identify predictors of pathologic down-staging. Results: 7,244 patients were identified with non-metastatic UTUC who underwent extirpative surgery in the study period. 260 patients (3.6%) received NAC, with the use of NAC increasing over time from 2.0% patients in 2006 to 7.1% of patients in 2014 (linear trend p < 0.001). Clinical and pathologic staging data were available for 119 and 2904 patients who did and did not receive NAC, respectively. Thirty patients (25.2%) who received NAC experienced pathologic down-staging, compared to 52 patients (1.8%) who did not receive NAC (p < 0.0001). On multivariable analysis, NAC was associated with a higher likelihood of pathologic down-staging (OR 10.2, 95% CI 5.4-19.3). Additional predictors of pathologic down-staging include a higher clinical T stage (p = 0.001) and African-American race (OR 2.7, 95% CI 1.1-6.6). Compared to renal pelvis UTUC, ureteral UTUC was associated with a similar likelihood of pathologic down-staging (OR 1.5, 95% CI 0.9-2.5). Conclusions: NAC is infrequently used among patients with UTUC undergoing extirpative surgery. A higher incidence of pathologic down-staging was observed among patients receiving NAC. These findings suggest clinical benefit of NAC with respect to pathologic outcomes in patients with UTUC and may help guide selection of patients for NAC prior to radical surgery until data from prospective studies becomes available.





2021 ◽  
Author(s):  
Henrique Diegoli ◽  
Vivianne Samara Conzatti ◽  
Suleimy Cristina Mazin ◽  
Juliana Safanelli ◽  
Louise Domenguini Chiaradia Dellatorre ◽  
...  

AbstractBackgroundThe city of Joinville had been mildly affected by the COVID-19 pandemic until June 2020. This study aimed to longitudinally assess the prevalence of exposure to the virus and social distancing practices in the local population.MethodsA randomized selection of households stratified by region was created. From June 15 to August 7, 2020, a dweller was randomized in each household, answered a questionnaire, and performed a test for the detection of SARS-CoV-2 antibodies. The prevalence of positive tests was calculated for each week and adjusted for the test’s sensitivity and specificity.ResultsThe adjusted proportion of positive results increased from 1.4% in the first week (margin of error [ME] 0% to 2.87%) to 13.38% in the eighth week (ME 10.22% to 16.54%). Among the 213 participants that tested positive, 55 (25.82%) were asymptomatic. Only 37 (17.37%) sought medical consultation for any symptom. Among the 77 (36.15%) that were leaving home to work or study, only 18 (23.38%) stopped due to any symptom. The proportion that referred going to bars, restaurants, or making non-essential shopping decreased from 20.56% in the first week to 8.61% during the peak of diagnoses.ConclusionThe low proportion of participants that sought medical consultation or stopped leaving home indicates strategies directed to isolate only those symptomatic reach a low proportion of infected patients.



2014 ◽  
Vol 24 (1-2) ◽  
Author(s):  
Kristian Tambs ◽  
Espen Røysamb

Original psychometric instruments are usually too lengthy and space-consuming to be suitable for general population based health studies. Usually, however, they can be abbreviated without losing more measurement precision than what can be accepted in such studies. Here we demonstrate that short-form versions of three instruments which are part of the MoBa study, and which include from one third to half the items in the original versions, correlate from 0.90 to 0.96 with the original version. This means that the short-form versions measure approximately the same characteristics as do the original instruments, and that they can safely be used for research purposes in MoBa.



2019 ◽  
Vol 161 (9) ◽  
pp. 1909-1915 ◽  
Author(s):  
Alexander Fletcher-Sandersjöö ◽  
Sadia Mirza ◽  
Gustav Burström ◽  
Kyrre Pedersen ◽  
Åsa Kuntze Söderqvist ◽  
...  


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