The Impact of Flow in an EEG-based Brain Computer Interface

Major issues in Brain Computer Interfaces (BCIs) include low usability and poor user performance. This paper tackles them by ensuring the users to be in a state of immersion, control and motivation, called state of flow. Indeed, in various disciplines, being in the state of flow was shown to improve performances and learning. Hence, we intended to draw BCI users in a flow state to improve both their subjective experience and their performances. In a Motor Imagery BCI game, we manipulated flow in two ways: 1) by adapting the task difficulty and 2) by using background music. Results showed that the difficulty adaptation induced a higher flow state, however music had no effect. There was a positive correlation between subjective flow scores and offline performance, although the flow factors had no effect (adaptation) or negative effect (music) on online performance. Overall, favouring the flow state seems a promising approach for enhancing users' satisfaction, although its complexity requires more thorough investigations

Standardization of Protocol Design for User Training in EEG-based Brain-Computer Interface

International audienceBrain-computer interfaces (BCIs) are systems that enable a personto interact with a machine using only neural activity. Such interaction canbe non-intuitive for the user hence training methods are developed to increaseone’s understanding, confidence and motivation, which would in parallel increasesystem performance. To clearly address the current issues in the BCI usertraining protocol design, here it is divided intointroductoryperiod and BCIinteractionperiod. First, theintroductoryperiod (before BCI interaction) mustbe considered as equally important as the BCI interaction for user training. Tosupport this claim, a review of papers show that BCI performance can dependon the methodologies presented in such introductory period. To standardize itsdesign, the literature from human-computer interaction (HCI) is adjusted to theBCI context. Second, during the user-BCI interaction, the interface can takea large spectrum of forms (2D, 3D, size, color etc.) and modalities (visual,auditory or haptic etc.) without following any design standard or guidelines.Namely, studies that explore perceptual affordance on neural activity show thatmotor neurons can be triggered from a simple observation of certain objects, anddepending on objects’ properties (size, location etc.) neural reactions can varygreatly. Surprisingly, the effects of perceptual affordance were not investigatedin the BCI context. Both inconsistent introductions to BCI as well as variableinterface designs make it difficult to reproduce experiments, predict their outcomesand compare results between them. To address these issues, a protocol designstandardization for user training is proposed

Project Level Pavement Management Optimization Procedure Combining Optimal Control Theory and HDM-4 Models

The paper presents an optimal control theory-based procedure for finding the optimal timing and intensity of pavement maintenance treatments, which was adjusted based on the models for pavement deterioration and road user costs from the HDM-4 and RUCKS models. The model for improvement in pavement condition after a maintenance treatment was calibrated according to Patersons bilinear model. The closed-form solution is then compared to the solution obtained by using genetic algorithms (GAs). In both methodologies special attention was given to the quality of the optimal solution in terms of evaluating: (i) the time between the maintenance treatments; (ii) minimal/maximal thicknesses of overlays calculated in the optimal maintenance plan; and (iii) parameters defining pavement condition before and after the maintenance treatment. The comparison between the two methodologies allowed analyzing limitations in each one of them and led to improvements in the optimal solution

Transport in magnetically doped topological insulators: Effects of magnetic clusters

We study the electron transport in a magnetically doped three dimensional topological insulator (TI) by taking the effects of impurity-impurity exchange interactions into account. The interactions between magnetic impurities give rise to the formation of {\it magnetic clusters} with temperature dependent mean sizes, randomly distributed on the surface of the TI. Instead of dealing with single magnetic impurities, we consider surface Dirac electrons to be scattered off magnetic clusters, and define the scattering potential in terms of clusters mean sizes. Within the semiclassical Boltzmann approach, employing a generalized relaxation time approximation, we obtain the surface conductivity of the TI by solving four sets of recursive relations and demonstrate that, the system is highly anisotropic and the surface conductivities possess non-monotonic behaviors, they strongly depends on the direction, the mean size and the number of magnetic clusters. We demonstrate that the dependence of the anisotropic magnetoresistance (AMR) to the spin direction of the magnetic clusters is inconsistent with the angular dependence of the TI doped with non-interacting magnetic impurities. Our results are consistent with the recent experiment on the AMR of the Cr-doped $\rm {(Bi, Sb)}_2{\rm Te}_3$ TI.Comment: 16 pages, 13 figure

Effects of quercetin and epicatechin on oxidativeantioxidative status of rats treated with copper(ii)- ions

Bakar kao esencijalni mikroelement ima važnu ulogu u biološkim sistemima međutim, povećane koncentracije mogu da izazovu toksične efekte. Kao prelazni metal, bakar može da stimuliše produkciju reaktivnih vrsta kiseonika preko Fenton-ove i Haber-Weiss-ove reakcije i dovede do oksidativnih oštećenja biomolekula u tkivima, pre svega u jetri koja učestvuje u njegovom metabolizmu. Flavonoidi su prirodna biljna polifenolna jedinjenja koja pokazuju širok spektar biološke aktivnosti. Antioksidativna svojstva mogu da ispolje različitim mehanizmima, u direktnoj reakciji sa reaktivnim vrstama ili helacijom jona prelaznih metala, koji bi u daljim reakcijama proizveli reaktivne vrste. Cilj istraživanja ove doktorske disertacije je ispitivanje efekata subhronične intoksikacije bakrom na hematološko-biohemijske parametre u krvi, oksidativni metabolizam eritrocita i parametre oksidativnog stresa u jetri pacova. Takođe, cilj je i ispitivanje protektivnog kapaciteta i sinergističkog delovanja flavonoida kvercetina (QE) i epikatehina (EC), kao čistih supstanci, u uslovima oksidativnog stresa. Upoređivani su i efekti primenjenih flavonoida i komercijalnog leka D-penicilamina (DPA), tiolnog jedinjenja koje se koristi za tretman oboljenja čiji je uzrok povećano akumuliranje bakra u tkivima (Vilsonova bolest). Studija je izvedena na mužjacima pacova soja Wistar albino, 8 nedelja starosti na početku eksperimenta, nasumično podeljenih u 5 grupa po 7 životinja: (1) kontrolna (0.3 ml fiziološkog rastvora, i.p.); (2) tretirana bakrom (CuCl2·2H2O u koncentraciji od 560 mg/L) preko vode za piće u trajanju od 5 nedelja; (3) tretirana bakrom (na način opisan prethodno) i DPA (50 mg/kg TT, u 0.3 ml redestilovane vode, i.p.) svakog drugog dana tokom poslednje 2 nedelje eksperimenta (ukupno 5 injekcija); (4) tretirana bakrom (na način opisan prethodno), a zatim flavonoidima QE i EC (40 mg QE/kg TT + 40 mg EC/kg TT, u 0.3 ml redestilovane vode, i.p.) svakog trećeg dana tokom poslednje 3 nedelje eksperimenta (ukupno 7 injekcija); (5) tretirana flavonoidima QE i EC (na način opisan prethodno). U punoj krvi određivani su hematološki parametri: broj eritrocita (RBC), koncentracija hemoglobina (Hb), hematokrit (Hct), broj leukocita (WBC), broj trombocita (Plt), hematološki indeksi, i biohemijski parametri: koncentracije elektrolita (K, Na, Ca, Fe, fosfata), koncentracije ukupnih proteina, albumina, glukoze i ukupnog holesterola, aktivnosti enzima aspartat aminotransferaze (AST), alanin aminotransferaze (ALT), alkalne fosfataze (ALP), gama-glutamil transpeptidaze (GGT) i laktat dehidrogenaze (LDH). U lizatu eritrocita, primenom standardnih analitičkih metoda, određivani su markeri oksidativnog stresa: koncentracije lipidnih peroksida (LPO), koncentracije reaktivnih vrsta kiseonika i azota (superoksid anjon radikala (O2 •-), vodonik peroksida (H2O2) i nitrita (NO2 -)), koncentracije redukovanog (GSH) i oksidovanog glutationa (GSSG) i aktivnosti enzima superoksid-dismuze (SOD), katalaze (CAT), glutation- peroksidaze (GSH-Px), glutation-reduktaze (GR), glutation-S-transferaze (GST). U izolovanom tkivu jetre, nakon homogenizacije, primenom standardnih analitičkih metoda takođe je određen redoks status (koncentracije LPO, neenzimskih antioksidanata GSH, GSSG i Vit C, i aktivnosti enzima AOS: ukupne SOD, CuZn SOD, Mn SOD, CAT, GSH-Px, GR i GST). Koncentracije bakra i ceruloplazmina određene su u plazmi i supernatantu tkiva jetre. Rezultati istraživanja pokazuju da bakar u subhroničnom tretmanu ispoljava direktan prooksidativni efekat na eritrocite i tkivo jetre pacova i pokazuje značajne toksične efekte na hematološko-biohemijske procese u krvi. Subhronična intoksikacija bakrom dovodi do povećanja LPO u eritrocitima i tkivu jetre, uzrokuje hemolizu eritrocita i anemiju, porast ukupnog holesterola, poremećaj homeostaze elektrolita. Nakon subhronične intoksikacije bakrom povišene su aktivnosti enzima AST, ALT, ALP, GGT i LDH, markera citotoksičnosti jetre u serumu. Oksidativnim oštećenjima eritrocita i tkiva jetre doprinosi povećana produkcija O2 •- i H2O2 i smanjenje neenzimskih antioksidanata, ćelijskog pula GSH i Vit C. Promene u aktivnostima enzima AOS posle subhronične intoksikacije bakrom takođe ukazuju na pojavu oksidativnog stresa u eritrocitima i tkivu jetre. Flavonoidi QE i EC pokazuju antioksidativnu sposobnost i umanjuju oksidativni stres nastao nakon subhroničnog izlaganja bakru. QE i EC stabilizuju membrane, blokiraju lipidnu peroksidaciju i time igraju ulogu u ublažavanju manifestacija toksičnosti u eritrocitima i tkivu jetre. Značajno povećavaju koncentracije neenzimskih antioksidanata GSH i Vit C u ćelijama, indukuju sintezu enzima AOS, čime doprinose povećanju antioksidativnog kapaciteta ćelija. Sinergističko delovanje flavonoida QE i EC, kao i citoprotektivna uloga koju pokazuju, može se pripisati njihovoj sposobnosti da heliraju metale i/ili uklanjaju O2 •- i N2O2. Rezultati takođe pokazuju da su QE i EC efektivniji u antioksidativnom delovanju u poređenju sa DPA, koji pored efikasnosti u heliranju metala ispoljava i prooksidativne efekte povećanjem lipidne peroksidacije u eritrocitima i tkivu jetre. Ovo istraživanje predstavlja doprinos kompletiranju naučnih saznanja o toksičnim efektima bakra, kao i kompleksnosti protektivnog delovanja flavonoida kvercetina i epikatehina na oksidativno-antioksidativni status eritrocita i ćelija tkiva jetre. Zbog širokog spektra biohemijskih i farmakoloških dejstava, posebno treba istaknuti značaj ispitivanih flavonoida u zdravoj ishrani, kao i u prevenciji i terapiji mnogih oboljenja.Copper is an essential trace element that plays an important role in biological systems, however, the increased concentration may cause toxic effects. As the transition metal, copper may stimulate the production of reactive oxygen species by Fenton's and Haber-Weiss reaction and lead to oxidative damage of biomolecules in the tissues, especially in the liver, which participates in its metabolism. Flavonoids are a natural plant polyphenol compounds which exhibit a wide spectrum of biological activity. They may exert antioxidant properties through different mechanisms, in a direct reaction with a reactive species,or by chelating transition metal ions, which in a further reaction may produce reactive species. The effects of subchronic copper intoxication on haematological and biochemical parameters in blood,oxidative metabolism of erythrocytes and oxidative stress parameters in rat liver are objectives of this dissertation research. The aim is also to examine the protective capacity and synergistic effects of flavonoids quercetin (QE) and epicatechin (EC), as a pure substances, under oxidative stress conditions. We also compared the effects of these flavonoids and a commercial drug D-penicillamine (DPA), a thiol compound used for the treatment of diseases caused by an increased accumulation of copper in the tissues (Wilson's disease). The study was performed on male albino Wistar rats, 8 weeks old at the beginning of the experiment,randomly divided into 5 groups of 7 animals: (1) control (0.3 ml of saline, i.p.); (2) copper-treated (CuCl2·2H2O at a concentration of 560 mg/L) through drinking water for 5 weeks; (3) treated with copper (as described previously), and DPA (50 mg/kg body weight in 0.3 ml of re-distilled water, i.p.) every other day during the last 2 week of the experiment (total number of injections were 5); (4) treated with copper (as described above), and flavonoids QE and EC (40 mg QE/kg body weight + 40 mg EC/kg body weight, in 0.3 ml of re-distilled water,i.p.) every third day during the last 3 weeks of the experiment (total number of injections were 7); and (5) treated with flavonoids QE and EC (as described previously). Hematological parameters: erythrocyte count (RBC),hemoglobin concentration (Hb), hematocrit (Hct), leukocyte count (WBC), platelet count (Plt), hematological indices, and biochemical parameters: concentration of electrolytes (K, Na, Ca, Fe, phosphate), total protein,albumin, glucose, and total cholesterol, the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT) and lactate dehydrogenase (LDH) were measured in the whole blood. Markers of oxidative stress: lipid peroxidation (LPO),the concentration of reactive oxygen and nitrogen species (superoxide anion radicals (O2 •-), hydrogen peroxide (H2O2) and nitrite (NO2 -)), reduced (GSH) and oxidized glutathione (GSSG) concentrations, and activities of AOS enzymes: superoxide-dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), and glutathione-S-transferase (GST) were determined in the erythrocyte lysate using standard analytical methods. In isolated liver tissue after homogenization, the redox status (LPO concentration, GSH, GSSG and Vit C concentration, and the activities of total SOD, CuZn SOD, Mn SOD, CAT, GSH-Px, GR, and GST) was also determined using standard analytical methods. The concentrations of copper and ceruloplasmin were determined in the plasma and in the liver tissue supernatant. The results show that copper in subchronic treatment exerts a direct pro-oxidative effect on erythrocytes and liver tissue of rats and significant toxic effects on haematological and biochemical processes in the blood. Subchronic intoxication with copper leads to an increase in LPO in liver tissue and in erythrocytes, causes haemolysis and anemia, increase in total cholesterol, electrolyte homeostasis disbalance. After subchronic copper intoxication activities of cytotoxicity liver markers AST, ALT, ALP, GGT, and LDH, in the serum were elevated. Increased production of O2 •- and H2O2 and the reduction of non-enzymatic antioxidants, GSH and Vit C, contribute to oxidative damage in red blood cells and liver tissue. Changes in the activities of the AOS enzymes after subchronic intoxication with copper also indicated the occurrence of oxidative stress in erythrocytes and liver tissue. Flavonoids QE and EC exhibit antioxidant capacity and reduce oxidative stress occurring after subchronic copper exposure. QE and EC stabilize the membrane, blocking the lipid peroxidation, and thereby play a role in mitigating the manifestation of toxicity in the erythrocytes and liver tissue. They significantly increase the concentration of non-enzymatic antioxidants GSH and Vit C in cells, induce synthesis of the AOS enzymes, thus contributing to increase the cells antioxidant capacity. The synergistic action of the flavonoids QE and EC, and a cytoprotective role which they exert, can be attributed to their ability to chelate metal ions and/or remove O2 •- and H2O2. The results also show that QE and EC were more effective in antioxidant activity when compared with the DPA, which in addition to the efficiency of chelating metal ions exerts prooxidant effects, by increasing lipid peroxidation in erythrocytes and liver tissue. This research is a contribution to the scientific knowledge of the toxic effects of copper, as well as the complexity of the protective effect of flavonoids quercetin and epicatechin in the oxidative-antioxidant status of red blood cells and liver tissue cells. Considering their wide range of biochemical and pharmacological effects, we should point out to the importance of the flavonoids in a healthy diet, as well as in the prevention and treatment of many diseases

Ex post analysis of road projects: resilience to crisis

This investigation aimed to reveal a mechanism of how different road projects' settings respond to macro-economic crisis. Qualitative and quantitative analyses were performed over a sample of 31 European road projects, in various funding arrangements and life cycle phases, all extracted from the Horizon 2020 BENEFIT project cases database. The project setting is described through a specific combination of project features and/or values of developed indicators. The analysis was applied to identify factors that contributed to projects' performance regarding the resilience to the global financial crisis of 2007-2008. By doing this, it became possible to determine potential liabilities of projects that are already in their implementation or use phases. The analysis showed there are equally strong contributors to a project's success within country-specific, as well as project-specific features. In order to boost resilience toward sudden and unpredicted disruptions, several factors have emerged, such as long term planning, investing in top priority projects (preferably medium size investments), with realistic traffic projections and experienced and responsible concessionaires, but also having in place strong regulatory bodies and government support. The identified mechanism of enhancing the resilience to crisis caused by a specific project setting can be beneficial to multiple stakeholders

Competencies for Creating an Integrated Approach in the Educational Process of Preschool Student Teachers

The preschool teacher is the main initiator of the dynamics and efficiency of the educational process. The children need to acquire more functional knowledge, which raises questions about the preschool teacher students’ competencIes. The paper emphasizes the necessity of raising awareness of preschool student teacherS about the importance of their role in enriching children’s experiences, and bringing scientific, musical and linguistic phenomena closer. This further implies modernization of university education by encouraging and raising students’ motivation to apply innovative approaches to work and the creation of specific competencies and skills. The competence of preschool student teachers in the realization of activities is not only reflected in building moral values and habits among children, but also in activating children’s potentials and encouraging creativity. The aim of the research was to examine the attitudes of preschool student teachers towards their competencies necessary for implementation of an integrated approach. The method of theoretical analysis and scaling techniques are used. The paper emphasizes the importance of extending specific professional competencies of preschool teacher students, as well as the importance of the continuous development of pedagogical knowledge for supporting holistic development of children, through monitoring, listening and supporting various children’s expression (sound and voice, dance, movement, narration, etc).Publishe

Ex post analysis of road projects: resilience to crisis

This investigation aimed to reveal a mechanism of how different road projects' settings respond to macro-economic crisis. Qualitative and quantitative analyses were performed over a sample of 31 European road projects, in various funding arrangements and life cycle phases, all extracted from the Horizon 2020 BENEFIT project cases database. The project setting is described through a specific combination of project features and/or values of developed indicators. The analysis was applied to identify factors that contributed to projects’ performance regarding the resilience to the global financial crisis of 2007–2008. By doing this, it became possible to determine potential liabilities of projects that are already in their implementation or use phases. The analysis showed there are equally strong contributors to a project’s success within country-specific, as well as project-specific features. In order to boost resilience toward sudden and unpredicted disruptions, several factors have emerged, such as long term planning, investing in top priority projects (preferably medium size investments), with realistic traffic projections and experienced and responsible concessionaires, but also having in place strong regulatory bodies and government support.The identified mechanism of enhancing the resilience to crisis caused by a specific project setting can be beneficial to multiple stakeholders

Molekularna karakterizacija medonosne pčele Apis mellifera carnica u Srbiji

The sequences COI-COII of the mitochondrial DNA region in honeybee from four geographically distant regions in Serbia (Vršac, Knjaževac, Kraljevo, and Vranje) are analyzed. The research was conducted on eight different, previously selected honeybee lines preserved (linear selection) in the four reprocenters for queen bees. All four studied honeybee lines differ in morphological and productive traits, each being specific for the corresponding region. In addition to analysis of the mtDNA sequences in Serbian honeybee, a comparative analysis of the phylogenetic group of so far known C2 haplotypes was also performed. The results revealed two novel polymorphic positions in the COI-COII mtDNA region, viz., h2 at position 3474 and l2 at position 3534 (a T nucleotide deletion in both cases) in honeybees from the regions of Vranje and Knjaževac, respectively. Two novel mtDNA haplotypes in the honeybee C2 phylogenetic group, together with C2I (the new polymorphic position l2 and G-A transition at position 3587) and C2J (the new polymorphic position h2), are described. Also, comparative analysis performed on sequences from GenBank data showed a high degree of similarity (similarity index = 99.4%) between the novel C2I mtDNA haplotype and an A. m. cypria haplotype originating from Turkey. Certain domestic Kranjska honeybee populations from Serbia represent an autochthonous gene pool that can be of great importance for further presentation of honeybee biodiversity. The present paper contributes to characterization of mtDNA in honeybee of Serbia.Analizirane su sekvence COI-COII regiona mitohondrijalne DNK kod medonosnih pčela iz četiri geografski udaljena regiona Srbije (Vršac, Knjaževac, Kraljevo i Vranje). Istraživanje je vršeno na osam različitih, ranije odabranih linija medonosne pčele koje se čuvaju-održavaju (linijska selekcija) u okviru četiri reprocentra za matice. Sve četiri istraživane linije medonosne pčele se na osnovu morfoloških i proizvodnih osobina razlikuju, i specifične su za odgovarajući region. Osim analize sekvenci mtDNK među srpskim medonosnim pčelama, izvršena je i uporedna analiza sa do sada poznatim haplotipovima C2 filogenetske linije. Rezultati su otkrili dva nova polimorfna mesta u COI-COII regionu mtDNK, i to h2 na mestu 3474 i l2 na mestu 3534 (u oba slučaja delecije T nukleotida) među medonosnim pčelama u regionu Vranja i Knjaževca, respektivno. Opisana su dva nova mtDNK haplotipa među medonosnim pčelama C2 f­ilogenetske linije, i to C2I (novo poimorfno mesto l2 i G-A tranzicija na mestu 3587) i C2J (novo polimorfno mesto h2). Takođe, uporednom analizom sa sekvencama iz GenBanke podataka, utvrđena je visoka sličnost (similarity index = 99.4 %) novog C2I mtDNK haplotipa sa jednim haplotipom A. m. cypria poreklom iz Turske. Pojedine populacije domaće kranjske medonosne pčele iz Srbije mogu predstavljati autohtoni genski pul što može biti od velikog značaja za dalje očuvanje biodiverziteta medonosne pčele. Ovim radom upotpunjena je mtDNK karakterizacija medonosne pčele u Srbiji