Multi-objective integer programming: An improved recursive algorithm

This paper introduces an improved recursive algorithm to generate the set of all nondominated objective vectors for the Multi-Objective Integer Programming (MOIP) problem. We significantly improve the earlier recursive algorithm of \"Ozlen and Azizo\u{g}lu by using the set of already solved subproblems and their solutions to avoid solving a large number of IPs. A numerical example is presented to explain the workings of the algorithm, and we conduct a series of computational experiments to show the savings that can be obtained. As our experiments show, the improvement becomes more significant as the problems grow larger in terms of the number of objectives.Comment: 11 pages, 6 tables; v2: added more details and a computational stud

A Rapid Method for Determining the Oxidative Stability of Oils Suitable for Breeder Size Samples

A method utilizing thin-layer chromatography with a flame ionization detector (TLC-FID) was developed for assessing the stability of breeder’s oil seed samples based on the formation of polar compounds. The results showed a linear relationship between peroxide value (PV) and the content of polar material in the oxidized oil. Oil samples oxidized very readily on chromarods, even at low temperature, which is a particular advantage for antioxidant screening. At 45 °C, the oil oxidation rate was relatively low, but the relationship between the content of polar material and reaction time was linear. At 65 °C, if the content of polar material was below 50 %, the above relationship was still linear. At different temperatures, the action of tocopherol appeared to vary slightly. For example, at 65 °C, the oxidative stability of the oil sample was determined by the content of tocopherol, especially γ-tocopherol. At 45 and 55 °C, the oxidative stability was determined by both the content of tocopherol and polyunsaturated fatty acids. Of the tocopherol isomers, γ-tocopherol exhibited the highest antioxidant potency, consistent with the published literature. These results suggest that chromarods provide good media for monitoring oil oxidation for antioxidant screening. A particular advantage is the use of very small oil samples, usually 1–2 μL, and the ability to analyze multiple samples at the same time

Optimising a nonlinear utility function in multi-objective integer programming

In this paper we develop an algorithm to optimise a nonlinear utility function of multiple objectives over the integer efficient set. Our approach is based on identifying and updating bounds on the individual objectives as well as the optimal utility value. This is done using already known solutions, linear programming relaxations, utility function inversion, and integer programming. We develop a general optimisation algorithm for use with k objectives, and we illustrate our approach using a tri-objective integer programming problem.Comment: 11 pages, 2 tables; v3: minor revisions, to appear in Journal of Global Optimizatio

The impacts of motivational framing of technology restrictions on adolescent concealment: evidence from a preregistered experimental study

Caregivers employ a range of motivational strategies to help regulate and protect adolescents using connective technologies. The present study explored a new conceptual model informed by self-determination theory (Deci & Ryan, 2000; Ryan & Deci, 2000) with a representative sample of 1,000 adolescents recruited nationwide within Britain, and using a confirmatory, pre-registered and open science methodology. In this experimental study we compared controlling (pressuring, coercive, or punitive) styles of restricting technology with neutral, and autonomy-supportive (empathic, choice-promoting) styles of restricting to predict adolescents’ concealing their technology use from caregivers. We further tested two mechanisms which might explain the links of condition and concealment: perceiving caregivers to be trusting, and experiencing reactance or the desire to do the opposite of what was instructed. Findings are discussed in terms of the role of regulation styles on interpersonal outcomes and adolescent development, and implications for technology use policy and recommendations to caregivers and teachers

Bilateral double-layered patella in a patient with advanced knee osteoarthritis

Double layered patella (DLP) is a rare anomaly of the patella that may go undiagnosed, especially in patients with progressive knee dysfunction and early degenerative changes. Clinical symptoms such as motion-dependent pain and anterior knee pain most typically occur in adolescents or young adults; however, gradually increasing pain and early generalised degenerative changes have also been seen in patients over 40 years old. Diagnosis of DLP could be difficult, especially in cases with coexisting arthrosis. DLP is considered to be pathognomonic for the diagnosis of multiple epiphyseal dysplasia and usually coexists with other anomalies seen in this syndrome, such as hip dysplasia. In extremely rare cases, DLP can occur as a solitary disorder. The prevalence of such cases, however, is unknown, and they could be easily misdiagnosed. Computed tomography and magnetic resonance imaging are the most sensitive radiological methods used in DLP diagnosis. This case report presents a case of a bilateral DLP incidentally found in a 47-year-old patient with advanced arthritis referred for arthroplasty because of increasing symptoms of knee joint failure with no other abnormalities recorded. An important goal of our case study is to raise the awareness of this abnormality with radiologists and orthopaedic surgeons

Efficacité des heuristiques de branchement pour le branch-and-bound multi-objectif : vers une gestion plus dynamique

National audienceLes problèmes d'optimisation combinatoire multi-objectif sont réputés pour être particulièrement difficiles à résoudre efficacement. Parmi les approches de résolution possibles, les algorithmes de branch-and-bound sont largement utilisés comme méthodes exactes, fondées sur un parcours arborescent de l’espace des solutions. Une des principales composantes de ces algorithmes est la stratégie de branchement, qui sélectionne à chaque étape de séparation la variable à instancier dans les sous-problèmes résultants. Pour un problème donné, il existe généralement plusieurs heuristiques de choix de la variable de séparation, les performances de ces heuristiques peuvent différer d'une instance à l'autre et il n'est souvent pas possible de définir une heuristique qui s’avère la plus performante sur l’ensemble des instances (cf. No Free Lunch Theorems). Classiquement les algorithmes de branch-and-bound appliquent une seule heuristique, fixe toute au long de la résolution..Dans ce travail nous cherchons à déterminer si l'application conjointe de plusieurs heuristiques lors d'une même résolution permet d'augmenter l'efficacité de l'algorithme. Nous nous intéressons plus particulièrement aux stratégies de branchement pour le problème du sac-à-dos binaire bi-objectif. Les heuristiques de branchement pour ce problème sont nombreuses, considérant soit un seul des objectifs, soit un compromis des deux objectifs. Dans un premier temps, nous tentons de mettre en évidence les forces et faiblesses de ces différentes heuristiques en fonction des instances, dans le but d'élaborer une stratégie statique mêlant plusieurs heuristiques. La diversité des instances rend cette tâche particulièrement difficile. Toutefois, nous sommes parvenus à montrer que la combinaison de différentes stratégies de branchement permet de réduire la taille de l'arbre de recherche. Nous avons ensuite défini des mesures de qualité pour ces heuristiques, que nous utilisons via un mécanisme d’apprentissage automatique pour sélectionner dynamiquement la stratégie de branchement à chaque séparation au cours du processus de branch-and-bound. Finalement, nous comparons l'efficacité de ce nouvel algorithme par rapport à l'emploi d'une stratégie unique de séparation et analysons les différents réglages de cette approche adaptative

Prevalence of generalised joint hypermobility in school-aged children from east-central European region

Background: There is no literature regarding joint mobility in children of the Central and Eastern Europe. Studies describing clinical characteristics and functional outcomes are still needed. The aim of this study was to assess the prevalence of generalised joint hypermobility (GJH) in the group of school-aged children from Vilnius, the capital city of Lithuania, in relation to different cut-off values of the Beighton score (BS), and to identify possible patients with joint hypermobility syndrome. Materials and methods: The representative sample of this study was calculated to be 760 subjects. A total of 778 children from different schools were screened for the mobility of joints. The medical examination included an assessment of joints’ hypermobility according to the BS. The presence of specific signs (marfanoid habitus, antimongoloid slant and drooping eyelids) was assessed additionally. Parents of all involved children were asked to answer the questions developed based on the Brighton criteria regarding the medical history of children. Results: The prevalence of GJH in school-aged children from Vilnius, depending on the BS cut-off value, was 19.2% (BS ≥ 4), 9.5% (BS ≥ 5) or 5.7% (BS ≥ 6). The increased range of mobility was most frequently detected in thumbs of school- -aged children. The frequency of hyperextension > 10o in knees was 7- to 8-fold lower than the frequency of hyperextension > 10o in a passive opposition of the thumb. The evaluation results were similar on the left and right sides in 87.4% cases of thumb opposition, 90.1% cases of hyperextension of 5th finger, 87.9% cases of elbow manoeuvres, and 94.8% attempts to hyperextend knee. Conclusions: The prevalence of GJH in school-aged children from Vilnius depends on the BS cut-off value and ranges from 5.7% to 19.2%.