Solving some problems in teaching by using combinatorial optimization methods

U ovom radu se istražuju neki aktuelni problemi kombinatorne optimizacije...In this work some actual combinatorial optimization problem are investigated..

An Integrated Intelligent CAD/CAPP Platform: Part II - Operation Sequencing Based on Genetic Algorithm

We present a platform for integrated CAD/CAPP part design based on Elementary Machining Features (EMF) and intelligent approach for setup planning and operation sequencing based on a genetic algorithm through two papers. In this paper, as Part II of this platform, CAD/CAPP integration was realized via information from the enriched EMF, as well as production rules and a genetic algorithm. This is done for the purpose of the automated machining operation sequencing. Operation sequencing was conducted by using the improved genetic algorithm (GA).The improved GA uses integer representation for operations and implements modified genetic operators, enabling the achievement of high results in a reasonable computational time. In the paper we present a comprehensive case study applied to some existing and one new industrial example, confirming a high level of usability of the proposed GA and overall platform. Experimental results show that the improved GA algorithm gives slightly better results than similar algorithms in literature. For industrial example, we use body of the hydraulics cylinder which consists of 52 EMF. After implementation of the proposed methodology, the optimal machining operation sequence was identified, as well as the total machining cost of 142.49 BAM

Bleeding complicating acute myocardial infarction in patients treated with primary percutaneous coronary intervention

Nekoliko randomizovanih kliničkih studija je pokazalo da pacijenti sa velikim krvarenjem kao komplikacijom akutnih koronarnih sindroma (AKS) i perkutane koronarne intervencije (PKI) imaju lošiji klinički ishod, sa povećanim rizikom od nastanka glavnih neţeljenih kardijalnih dogaĎaja (MACE), koji obuhvataju smrtni ishod, infarkt miokarda, šlog i trombozu stenta, u odnosu na bolesnike bez krvarenja. Prema tome, prvencija krvarenja je postala isto toliko značajna kao prevencija ishemijskih dogaĎaja. MeĎutim, napore da se ovo sprovede ometa nedostatak jednobraznosti u definicijama krvarenja koje se danas koriste. U cilju standardizacije brojnih definicija krvarenja kod bolesnika koji primaju antitromboznu terapiju, tim naučnika okupljen oko Bleeding Academic Research Consortium-a (BARC) je nedavno konsenzusom doneo klasifikaciju krvarenja koristeći hijerarhijski pristup pri opisu stepena teţine krvarenja. Pošto se od nove jedinstvene definicije krvarenja očekuje da bude široko prihvaćena u kliničkim studijama i svakodnevnoj kliničkoj praksi, potrebno je da se njena vrednost potvrdi putem primene na već postojećim podacima o krvarenju ili podacima sakupljenim putem budućih kliničkih studija. Cilj: Glavni cilj ove studije je da ispita odnos izmeĎu bolničkog krvarenja procenjenog prema BARC klasifikaciji i kratkoročnog i dugoročnog mortaliteta/MACE-a kod neselektovane populacije bolesnika sa akutnim infarktom miokarda sa elevacijom segmenta ST (STAIM) podvrgnutih hitnoj koronarnoj angiografiji i lečenih metodom primarne PKI. Metode: Studija je obuhvatila 1808 konsekutivnih bolesnika sa STAIM, primljenih u periodu od avgusta 2009 do januara 2011 godine na Odeljenje urgentne kardiologije Kliničkog centra Srbije u Beogradu radi lečenja metodom primarne PKI. Podaci o bolesnicima sakupljeni su prospektivno i uneti u jedinstvenu elektronsku bazu podataka. Bolesnici su grupisani prema teţini krvarenja po BARC klasifikaciji (tip 0+1, tip 2, tip 3a, tip 3b, tip 3c, tip 5a i tip 5b)...Background: Several randomized trials have demonstrated that patients with major bleeding complicating acute coronary syndromes (ACS) and percutaneous coronary intervention (PCI) have worse clinical outcomes with increased risk of subsequent major adverse cardiac events (MACE), including death, myocardial infarction, stroke and stent thrombosis than those without bleeding. Therefore, prevention of bleeding has become equally as important as the prevention of ischemic event. However, this effort is hampered by the lack of uniformity in bleeding definition currently in use. In order to standardize multiple bleeding definitions for patients receiving antithrombotic therapy, the Bleeding Academic Research Consortium (BARC) has recently developed a consensus classification for bleeding by using a hierarchical approach to describe bleeding severity grade. Since newly proposed unified bleeding definition is expected to be widely accepted in clinical trials and real-world clinical practice, it must be validated with the use of existing data sets or data collected by future clinical trials. Objective: The main objective was to investigate the relationship between in-hospital bleeding as defined by BARC consensus classification and short-term and long-term mortality/MACE in unselected patient population who underwent emergency coronary angiography and primary PCI for STEMI. Methods: Our study obtained 1808 consecutive patients with STEMI admitted for primary PCI between August 2009 and January 2011 at the Department of Cardiology, Clinical Center of Serbia, Belgrade. Data of patients who experienced in-hospital bleeding were collected prospectively and entered into the dedicated electronic database. Patients were grouped according to the BARC categorization of bleeding (type 0+1, type 2, type 3a, type 3b, type 3c, type 5a and type 5b)..

Nonoclusive thrombosis of mechanical mitral valve prosthesis caused by inadequate treatment of anticoagulant therapy resistance

Background. Oral anticoagulants have been used in the prevention of thromboembolic complications for over six decades. A rare, but possible problem in the application of these medications could be resistance to them. Case report. We presented a patient with nonocclusive thrombosis of the mechanical mitral prosthesis due to inadequately treated resistance to peroral anticoagulant therapy. Resistance to oral anticoagulant medications was proven by an increased dosage of warfarin up to 20 mg and, after that, acenokumarol to 15 mg over ten days which did not lead to an increase in the international normalized ratio (INR) value over 1.2. On the basis of information that she did not take food rich in vitamin K or medications which could reduce effects of oral anticoagulants, and that she did not have additional illnesses and conditions that could cause an inadequate response to anticoagulant therapy, it was circumstantially concluded that this was a hereditary form of resistance. Because of the existing mechanical prosthetics on the mitral position, low molecular heparin has been introduced into the therapy. The patient reduced it on her own initiative, leading to nonocclusive valvular thrombosis. Conclusion. When associated complications like absolute arrhithmia does not exist, the finding of resistance to oral anticoagulant agents is an indication for the replacement of a mechanical prosthetic with a biological one which has been done in this patients

Laparoscopic technique as a method of choice in the treatment of non-parasitic splenic cysts

Introduction/Objective Splenic cysts are a rare clinical entity. In their origin, they may be parasitic or non-parasitic. They are classified as either primary (true) or secondary cysts (pseudocysts), depending on the presence or absence of an epithelial lining of the lumen. Methods Using a retrospective case study, we included 29 patients undergoing laparoscopic surgery due to splenic cysts. The patients were treated within the 2007-2017 period at the Clinic for Digestive Surgery, the Clinical Center of Serbia. We analyzed pre-operative, intra-operative and post-operative characteristics of laparoscopic technique in treating non-parasitic splenic cysts. Results The group of 29 patients treated with laparoscopic technique surgery due to the previously diagnosed splenic cyst, consisted of 12 (41.4%) men and 17 (58.6%) women. The average age of patients undergoing surgery was 38.86 ± 10.4 years (22-62). Based on the histopathological findings, there were eight epithelial cysts and 21 pseudocysts of the spleen. The maximal diameter of the splenic cyst, measured pre-operatively, was 10.09 ± 2.51 cm on average. The average operative time was 35 minutes, and the intra-operative bleeding amount was 11.48 ± 3.78 ml. None of the intra-operative complications, injury to the spleen or other organs of the abdomen, conversions to open surgery or reintervention were recorded. Conclusion Laparoscopic fenestration with excision of the part of the spleen cyst wall (marsupialization) represents an effective and definitive treatment for this disease. It is an alternative to splenectomy, along with other well-known benefits ensured by the spleen preservation. Low probability of occurrence of intra-operative and post-operative complications, as well as minimal trauma of tissue, results in a shorter postoperative stay, rapid recovery, and better quality of life. © 2019, Serbia Medical Society. All rights reserved

VERIFICATION OF CALCULATION METHOD FOR DRONE MICRO-DOPPLER SIGNATURE ESTIMATION

Drones micro-Doppler signatures obtained by FMCW radars are an excellent procedure for malicious drone detection, identification and classification. There are a number of contributions dealing with recorded spectrograms with these micro-Doppler signatures, but very low number of them has analyzed possibility to calculate echo caused by drone moving parts. In this paper, starting from already existing mathematical apparatus, we presented such spectrograms as a function of changing drone moving parts characteristics: rotor number, blades number, blade length and rotor moving speed. This development is the part of a wider project intended to prevent malicious drone usage

Age structure of yellow-necked mouse (Apodemus flavicollis Melchior, 1834) in two samples obtained from live traps and owl pellets

The age structure of yellow-necked mouse (Apodemus flavicollis Melchior 1834) has been analyzed in individuals obtained by two methods: Trapping with Sherman live traps and obtainment of skulls from long-eared owl (Asio otus Linnaeus, 1758) pellets (predator diet analysis). One hundred and forty-four mice were analyzed for the degree of wear of the surface of molar crowns, and an additional 74 measurements were performed on captive-born Apodemus flavicollis individuals. We used a refined model of comparison that included seven classes of mouse age, rather than four classes, as suggested by other authors.Uzrasna struktura Apodemus flavicollis (Melchior, 1834) analizirana je na uzorku pribavljenom primenom dve metode: izlovljavanjem Šermanovim klopkama i prikupljanjem lobanja miševa iz gvalica sove Asio otus Linnaeus. Kod ukupno 144 jedinke studiran je stepen izrabljenosti molarnih krunica; izvršena su i 74 dodatna merenja kod jedinki gajenih u laboratorijskim uslovima. Tokom istraživanja korišćen je redefinisani model kombinacije sedam uzrasnih klasa miševa (a ne četiri, kako su ranije sugerisali pojedini stručnjaci).Projekat ministarstva br. 156

Analysis of the CYP2C19 genotype associated with bleeding in Serbian STEMI patients who have undergone primary PCI and treatment with clopidogrel (vol 74, pg 443, 2018)

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Prediction of GO terms for IDPs based on highly connected components in PPI networks

Partitioning large biological networks can help biologists to retrieve new information for particular biological structures. In literature, various methods for partitioning and clustering biological networks have been proposed. The aim of such a network partitioning is to retrieve smaller structures which are easier to analyse, but still containing important information about relations between the network elements. Highly connected deletion problem is one of such network partitioning, with the aim to partition a network into highly connected components (hcd components) by deleting minimum number of edges. A network component with n nodes is a hcd component if the degree of every vertex is larger than n/2. For the purpose of this research, we used a specially constructed local search based heuristic approach to identify hcd components. Dealing with protein-protein interaction (PPI) networks, it has been noticed that proteins from the same hcd component in a network have same Gene Ontology (GO) annotations. Based on that, we proposed a new method for prediction of GO annotations, which consists of the following steps: (a) starting PPI network is partitioned to hcd components; (b) the obtained hcd components are expanded by proteins which became singletons in the partition set; (c) the newly formed extended hcd components are the subject of further enrichment analysis in DiNGO tool, which returns a list of existing GO terms for proteins from the considered extended component; (d) after propagation through GO hierarchy, the extended list of GO is obtained; (e) each protein from the extended hcd component is annotated by a number of GO terms obtained from the previous step; The proposed method is tested on the data from CAFA-3 challenge. Comparing the F1-measure of the obtained results, a combination of parameters (type of extension, cutoff for enrichment analysis and maximum number of GO terms) with the best performances is selected for the further usage. The method with the selected parameters was further applied on a class of Intrinsically Disordered Proteins (IDP). Preliminary results indicate that this method can be useful for proposing new GO terms for IDP proteins