Influence of a trout farm on macrozoobenthos communities of the Trešnjica river, Serbia

Trout farming poses an increasing threat to quality of the water of clean highland streams. Research of this problem has focused primarily on changes in physico-chemical composition of the water and structure of the river bottom, and less on the effects on living organisms. In the present work, we investigated influence of the farm with the highest trout production in Serbia, the 'Riboteks' Trout Farm on the Trešnjica River, on its macrozoobenthos communities. Our investigations showed that the 'Riboteks' Trout Farm wastewaters caused a clear and statistically significant change of moderate intensity in all measured parameters describing the composition and structure of macrozoobenthos communities. These changes were most pronounced in the part of the watercourse closest to the influx of waste water (locality III) but remained statistically significant even 500 m downstream (locality IV) and were lost only about 3.5 km away from the influx of the farm's wastewater (locality V). The most pronounced were changes in the participation in total abundance of the Baetidae, Chironomidae, and Plecoptera. Additionally, results of the present work confirmed that the mass of fish on the trout farm is a parameter that adequately defines the strength of its action, above all the intensity of its influence on structure of the macrozoobenthos community

Assessment of proposed business plans of on-trip and pre-trip information in the LRT system (public urban transit) of the city of Zagreb

The quality of public urban transit organization depends to a great extent also on the organization and the quality of on-trip and pre-trip information services. The aim of this service is to provide relevant, accurate and usable traffic and transport information to current users of the public urban transit, as well as to attract new users, alleviating the burden on the roads and insuring high-quality transport service to motorists who at least on one section of their trip use public transport means. Apart from classical information forms this system greatly relies also on new telecommunication technologies including the third generation of mobile networks and mobile Internet. Apart from the wide range of methods of collecting information, their processing and dissemination, the entire problems of introducing the mentioned services into the newly organized system such as LRT needs to be systemically analyzed. It is especially important to analyze in advance and to define the relations between the private and public sector in the described process. The paper considers the corporate plans of organizing the system of on-trip and pre-trip information in the LRT system applicable in the City of Zagreb. Their implementability has been evaluated by a professional team defining the relevant factors in the selection of the corporate plan

Evaluacija genotoksičnih efekata tiroksina primenom in vivo citogenetičkog testa na Swiss albino miševima

Thyroid hormones enhance aerobic metabolism favoring oxidative stress which may lead to covalent damage of various molecules including DNA. Previous investigations revealed that thyroid hormones induce DNA damage on human lymphocytes and sperm in the in vitro Comet assay. However, cytogenetic evaluation of genotoxic effects of thyroxine gave equivocal results: increase of sister chromatid exchanges, and no incerase of micronuclei in cultured human lymphocytes. Therefore, the aim of the present study was to further evaluate the possible genotoxic effects of thyroxine using in vivo cytogenetic test on Swiss albino mice. Three experimental concentrations of thyroxine were used (0.1 mg/kg, 0.5 mg/kg and 2.5 mg/kg). The mice were divided into several groups depending on the duration of the treatment with thyroxine. Thus, we treated mice for 1, 3, 7 and 10 days. Positive (Nmethyl- N'-nitro-N-nitrosoguanidine) and negative controls were also formed for the same time periods. Cytogenetic endpoinds (numerical and structural aberrations, chormosome gaps and breaks) were analysed in bone marrow cells from femures. The results obtained in this investigation showed that thyroxine has not induced chromosome damage or aberrations. This is in agreement with our previous analysis of micronuclei in human peripheral blood lymophocytes treated with thyroxine. On the other hand, we observed a decrease of mitotic index especially in animals treated for a longer period of time with the highest dose of thyroxine. Therefore, it can be concluded that thyroxine does not induce genotoxic effects which could be detected by cytogenetic analysis.Tireoidni hormoni podstiču aerobni metabolizam favorizujući oksidativni stres koji može da dovede do kovalentnih oštećenja različitih molekula uključujući i DNK. U prethodnim istraživanjima otkriveno je da tireoidni hormoni indukuju oštećenja molekula DNK u humanim limfocitima i spermi u in vitro Komet testu. Međutim, citogenetička evaluacija genotoksičnih efekata tiroksina dala je kontradiktorne rezultate: povećanje razmena sestrinskih hromatida bez porasta učesalosti mikronukleusa u kulturama humanih limfocita. Stoga je cilj istraživanja u ovom radu bio da dodatno ispitamo moguće genotoksične efekte tiroksina koristeć i in vitro citogenetički test na Swiss albino miševima. Upotrebljene su tri eksperimentalne koncentracije tiroksina (0,1 mg/kg, 0,5 mg/kg and 2.5 mg/kg). Miševi su podeljeni u nekoliko grupa zavisno od dužine tretmana tiroksinom: 1, 3, 7 i 10 dana. U istim vremenskim periodima miševi su tretirani pozitivnom (N-metil-N'-nitro-N-nitrozogvanidin) i negativnom kontrolom. Analizirani su citogenetički parametri (numeričke i strukturne aberacije hromozoma, gapovi i prekidi na hromozomima) u ćelijama kostne srži izolovanim iz femura. Rezultati dobijeni u ovom istraživanju ukazuju da tiroksin ne indukuje hromozomske prekide i aberacije, što je u saglasnosti sa našim prethodnim zapažanjima na humanim limfocitima u kulturi. Istovremeno, primetili smo smanjenje mitotskog indeksa, naročito kod životinja tretiranih u dužem vremenskom periodu sa visokim dozama tiroksina. Prema tome, može se zaključiti da tiroksin ne indukuje genotoksične efekte koji mogu da se detektuju citogenetičkim analizama

Jovanka Broz and Serbian public from 1952 to 2013.

Život Jovanke Broz, supruge dugogodišnjeg predsednika jugoslovenske vlade i republike, do sada nije bio predmet sistematskog naučnog istraživanja. Nije objavljena ni njena sveobuhvatna naučna biografija niti istražena uloga u politici Socijalističke Federativne Republike Jugoslavije. Takođe, nisu sa naučnog stanovišta sagledani ni razni aspekti njenog delovanja u javnosti – pre svega sociološki i antropološki. Odnos srpske javnosti prema supruzi jedinog predsednika SFR Jugoslavije takođe nikada nije bio predmet sistematske naučne analize. Ona bi bila veoma važna za procenu uloge Jovanke Broz u istoriji Srbije i Jugoslavije druge polovine 20. i početka 21. veka. Neformalna i formalna uloga Jovanke Broz u najdugotrajnijem mirnom razvoju Balkana u 20. veku važna je za rekonstrukciju drugih, savremenih istorijskih tema. Uloga Jovanke Broz još je značajnija zato što ona nije bila deo partijske oligarhije iz predratnog ili poratnog vremena, nije imala službene funkcije, ali je tokom dugogodišnjeg bračnog života i nastupanja u javnosti zajedno sa Josipom Brozom stekla toliki značaj da se tokom sedamdesetih godina ponekad u suprotstavljenim krugovima u SKJ i među protivnicima režima spekulisalo da je u SFR Jugoslaviji ustvari uspostavljeno savladarstvo. Retke su istorijske ličnosti za čije je naučno predstavljanje toliko važan odnos javnosti prema njima, kao što je to bio slučaj sa Jovankom Broz. Tokom više od šest decenija njena uloga bila je manje formalna i zavisila je od slike koja je o njoj stvorena i stava javnosti. Istražujući stav javnosti prema Jovanki Broz na osnovu periodike, memoarske građe, neobjavljenih izvora i medijskih izveštaja u ovoj disertaciji nudimo rekonstrukciju života Jovanke Broz i njenog doba.The life of Jovanka Broz, the wife of Josip “Tito” Broz, the long-serving president of the Yugoslav government and republic, has not yet been the subject of systematic scholarly research. Neither has her comprehensive scholarly biography been published, nor her role in the politics of the Socialist Federal Republic of Yugoslavia researched. Additionally, different aspects of her public activity, primarily the sociological and anthropological ones, have not been studied from a scholarly stance. Furthermore, the attitude of the Serbian public towards the wife of the only president of the SFR of Yugoslavia has never been the subject of a systematic scholarly analysis. However, such a study would be very important for the assessment of the role Jovanka Broz played in the history of Serbia and Yugoslavia in the second half of the 20th century and the beginning of the 21st century. The informal and formal role Jovanka Broz had in the longest period of peaceful development of the Balkans in the 20th century is also important for the reconstruction of other contemporary historical topics. The role of Jovanka Broz is even more important because she did not belong to the prewar or post war party oligarchy and had no official functions. Nevertheless, during her long marriage and public appearances with Josip Broz, she acquired such importance that during the 1970s, sometimes both in the opposing circles within the League of Communists of Yugoslavia and in circles opposing the regime, there were speculations that actually co-ruling was established in SFR of Yugoslavia. Rarely do we see historical figures whose scholarly presentation depends so much on public opinion as is the case of Jovanka Broz. For more than six decades, her role was less formal depending on the image of her that was created and on public opinion. This dissertation aims to offer a reconstruction of the life of Jovanka Broz and her time by researching the attitude the public had towards Jovanka Broz based on periodicals, memoirs, unpublished sources and media reports

Analysis of coronary flow velocity reserve, TIMI flow and global longitudinal strain in women with cardiac syndrome X

Populacija osoba sa bolom u grudima i normalnim nalazom koronarografije je heterogena. Kardijalni sindrom X (eng. Cardiac Syndrome X - CSX) je najčešće zastupljen kod žena perimenopauzalne životne dobi, a definisan je pojavom bola u grudima, depresijom ST segmenta na testu opterećenja i angiografski isključenom epikardnom koronarnom bolesti. Mikrovaskularna disfunkcija (MVD) i posledična ishemija povezana je sa lošijom kliničkom prognozom i najverovatnije je objašnjenje elektrokardiografske pozitivnosti stres eho testova i simptoma bola u grudima kod žena sa CSX. Longitudinalna funkcija leve komore (LK) je posebno vulnerabilna na pojavu mikrovaskularne ishemije te se ona smatra ranim markerom subkliničke sistolne disfunkcije LK. Iako su u dosadašnjoj literaturi CSX i angiografski fenomen usporenog protoka kontrasta (eng. Slow Coronary Flow - SCF), koji se karakteriše usporenom opacifikacijom koronarnih arterija kontrastnim sredstvom u odsustvu epikardne bolesti, posmatrani kao zasebni klinički entiteti, bitno je napomenuti činjenicu da oni imaju zajednički patofiziološki supstrat – primarnu abnormalnost koronarne mikrocirkulacije - MVD. U tom smislu u aktuelnoj literaturi do sada nema podataka o proceni očuvanosti mikrovaskularne funkcije i sistolne longitudinalne funkcije LK u CSX populaciji stratifikovanoj prema prisustvu SCF. Cilj: Osnovni cilj naše studije je bio da se kod bolesnica sa CSX stratifikovanih po podgrupama u zavisnosti od prisustva SCF, analizira mikrovaskularna funkcija kvantifikacijom koronarne rezerve protoka (eng. Coronary Flow Velocity Reserve - CFVR) i kontraktilna funkcija LK metodom globalnog indeksa naprezanja (eng. Global Longitudinal Strain - GLS). Metode: Ispitivana populacija je uključivala 70 žena sa CSX (61±7 godina starosti) i 34 po godinama adaptiranih žena iz kontrolne grupe. Ovo istraživanje je sprovedeno u periodu od januara 2014. godine do juna 2019. godine na Klinici za kardiologiju Kliničkog centra Srbije. CSX grupa je stratifikovana u dve podgrupe u zavisnosti od prisustva SCF utvrđenog koronarnom angiografijom: CSX- eng. Thrombolysis In Myocardial Infarction -TIMI 3- podgrupa sa normalnim protokom (n = 38) i CSX-TIMI 2- podgrupa sa SCF (n = 32). Ispitanicama iz CSX i kontrolne grupe učinjen je klinički i ehokardiografski pregled, stres eho test, merenja CFVR-a za levu prednje descendentnu (eng. left anterior descending - LAD) i posterodescendentnu (eng. posterior descending - PD) koronarnu arteriju, kao i kvantifikacija GLS LK u miru i nakon opterećenja...Patients with chest pain and normal coronary arteries represent a rather nonhomogeneous population. Cardiac syndrome X (CSX) is defined by angina-like chest pain, ST segment depression during exercise and normal coronary arteries found mostly in post-menopausal women. Microvascular dysfunction (MVD) and consecutive ischemia carry an adverse prognosis, and most probably account for angina symptoms and electrocardiographically positive stress tests in women with CSX. Left ventricular (LV) longitudinal function is particularly susceptible to the effects of microvascular ischemia and as such is considered an early marker of subclinical systolic dysfunction. Although angiographic phenomenon of slow coronary flow (SCF) characterized by delayed opacification of coronary arteries in the absence of an obstructive coronary disease and CSX are still considered separate clinical entities in the contemporary literature, it is important to note that they share the same underlying mechanism of primary abnormality of microvascular function – MVD. In that sense, evaluation of microvascular and LV systolic longitudinal function in CSX patients with regard to the presence of SCF have not been investigated yet. Objective: The main objective of our study was to assess microvascular function by coronary flow velocity reserve (CFVR) and LV contractile function by global longitudinal strain (GLS) in CSX patients with respect to presence of SCF. Methods: Study population consisted of 70 women with CSX (mean age 61±7 years) and 34 age- and gander matched controls. All the women were recruited at the Cardiology Clinic, Clinical center of Serbia, Belgrade, during the period from January 2014 to June 2019. CSX group was stratified into two subgroups depending on SCF presence: CSX- Thrombolysis In Myocardial Infarction -TIMI 3 normal flow subgroup (n=38) and CSX-TIMI 2- SCF subgroup (n=32) as defined by coronary angiography. Both women from the CSX and the control group had clinical and echocardiographic examination, stress echo test, CFVR measurements for left anterior descending (LAD) and posterior descending (PD) artery as well as LV GLS at rest and during exercise performed. Left heart catheterization was performed for the whole CSX group, while none of the controls have undergone coronary angiography because of ethical reasons. Clinical status of the women from the CSX group was evaluated on the basis of Seattle Angina Questionnaire (SAQ)..

Mystical principle and weltgefühl in Musil's novel "The man without qualities"

Предмет истраживања, модерни роман Човек без својстава (Чбс) аустријског писца Роберта Музила (1881-1942), анализиран је са аспекта поља сензитивне мистике која је препозната као окосница света дела и ауторове теоријске мисли, изнете кроз есеје. Последњи се могу сматрати колевком поетолошке парадигме самог аутора отелотворене романом. Шира анализа је показала да је научно проучавање концепта другачијег станња донекле занемаривало његову осећајну структуру, која се показује као комплексан суоднос Ја и Света. Један од закључака истраживања, који се тиче интерпретативних могућности у оквиру самог дела, јесте истицање Музиловог другачијег стања као мистичног осећања света. Поред анализе осећајног слоја другачијег стања, – које је смештено у домен ирациоидног код Музила и преко којега се конституише поетика ноеодређености, заснована на ”неодређеном осећању” као синониму за ”другачије осећање”, – анализи су подвргнуте и импликације које овај концепт аутора има по читања поетских, естетских и етичких ставова изнетих делом....The subject of our research, (which is) the modernist novel ‘The Man Without Qualities’ by the Austrian writer Robert Musil (1881-1942) was examined against the background of the definition of the mystical. The mystical represents the backbone of the narrated world and of the author’s theoretical considerations spread throughout his essays, which could be viewed as the cradle of the poetical paradigm found within the novel. A broader, previously conducted analysis has shown that the research literature largely ignored the concept of the other state regarding its emotional structure, which emerges as a complex I–world relation. One of the study’s main conclusions is that the other state may be interpreted as a mystical world feeling i.e. Weltgefühl. Musil places the other state in the domain of the irratioïd, whereby this study takes into account its implications for the poetic, aesthetic and ethical readings of the novel’s text. In addition to the aforementioned, the study tracks the fate of the phrase invisible principle as an element of the novel’s intrinsic mystical paradigm. The term invisible principle is an intertextual borrowing that Musil acquired from Maeterlinck through whom Neo-Platonic ideas are introduced to the narrative flow, deepening the mystical dimension of the novel. Conceived in the spirit of the Plotinian scriptures, the invisible principle is considered in this study as a mystical principle enabling the vision of the One or the First Principle (ancient Greek ἀρχή). The same can also be interpreted as the principle of wisdom, or one of judgment in matters regarding mind and soul. Specifically, in Musil, it’s observed to be a founding moral principle of human action, which one can mystically trace in the other state...

In vitro investigation of antitumor activities of extracts of endemic plant species Helichrysum zivojini Černjavski et Soška U

Bioaktivni sastojci biljnih vrsta nalaze se u centru pažnje istraživanja u savremenoj onkologiji zbog svoje moguće uloge u hemioprevenciji, odnosno inhibiciji različitih koraka procesa maligne transformacije. Antikancerski potencijal biljnih jedinjenja zasniva se na mogućnosti redukcije slobodnih radikala, regulacije karcinogen-aktivirajućih i karcinogen-detoksifikujućih enzima, kao i mogućnosti inhibicije inflamatornih citokina, zatim na mogućnosti da dovedu do promena u regulaciji faktora rasta i ciljnih molekula signalnih puteva koji kontrolišu ćelijski rast, proliferaciju i apoptozu, kao i angiogenezu, invaziju i metastazu malignih ćelija. Osnovni cilj istraživanja je bio da se ispita citotoksičnost, odnosno odrede intenzitet i mehanizmi citotoksičnog dejstva pet ekstrakata izolovanih u vidu frakcija iz endemične biljne vrste Helichrysum zivojinii Černjavski et Soška prema specifičnom malignom ćelijskom tipu, kao i da se odredi selektivnost u antitumorskom dejstvu prema nizu humanih malignih ćelija, kako u odnosu na poreklo - tip tumora, tako i u odnosu na zdrave mononuklearne ćelije periferne krvi (PBMC). Kako bi se doprinelo boljoj proceni antitumorskog potencijala ekstrakata, ispitan je i uticaj ekstrakata na invazivnost humanih metastatskih malignih ćelija i na angiogenezu endotelijalnih ćelija. Hemijska karakterizacija biljnih ekstrakata je imala za cilj da omogući razumevanje veze između kvalitativnog sastava i intenziteta citotoksične aktivnosti ekstrakata. Citotoksična aktivnost pet ekstrakata endemične biljne vrste Helichrysum zivojinii Černjavski et Soška je ispitana na sledećim humanim malignim ćelijskim linijama: HeLa (adenokarcinom cerviksa), Fem-x (melanom), K562 (mijeloidna leukemija), MDA-MB-361 (adenokarcinom dojke), MDA-MB-231 (adenokarcinom dojke), kao i prema EA.hy926 ćelijama (transformisane humane endotelijalne ćelije umbilikalne vene)...Bioactive constituents of plants are in the center of attention of modern cancer research due to their prospective role in cancer chemoprevention based on the suppression of different stages in malignant transformation. The anticancer potential of plant compounds could be attributed to their ability to scavenge free radicals, regulate carcinogen-activating and –detoxifying enzymes and inhibit inflammatory cytokines, than to induce changes in the regulation of growth factors and target molecules in oncogenic signal transduction pathways implicated in cell growth, proliferation, apoptosis, as well as in angiogenesis, invasion and metastasis of cancer cells. The aim of this research was to investigate the cytotoxicity, more exactly to determine the intensity and mechanisms of the cytotoxic actions of the five extracts isolated as fractions from the endemic plant species Helichrysum zivojinii Černjavski et Soška against specific malignant cell type, as well as to determine the selectivity in their antitumor actions against malignant cell lines of different tumor origin and against healthy peripheral blood mononuclear cells (PBMC). To fully evaluate the antitumor potential of extracts, the examination of their effects on the invasiveness of human metastatic malignant cells as well as on the angiogenesis of endothelial cells was done. Chemical characterization of plant extracts was performed in order to understand the relation between qualitative composition and intensity of cytotoxic action of the investigated extracts. The cytotoxic activities of the five extracts of the endemic plant species Helichrysum zivojinii Černjavski et Soška were tested against selected human malignant cell lines: HeLa (cervix adenocarcinoma), Fem-x (melanoma), K562 (myelogenous leukemia), MDA-MB-361 (breast adenocarcinoma), MDA-MB-231 (breast adenocarcinoma), as well as against transformed human umbilical vein endothelial EA.hy926 cells..

Users' efficiency, effectiveness, cognitive style and emotional reactions to computer interface based on different data model

Informaciona usklađenost kompjuterskog sistema i korisnika, kao predmet kognitivne ergonomije, počiva na dobro osmišljenom korisničkom interfejsu koji strukturom i informacionim obimom treba da omogući optimalnu interakciju u složenom sistemu čovek‐računar. U osnovi vizuelne forme interfejsa stoji, pored ostalog, logika po kojoj su podaci raspoređeni, međusobno povezani i dostupni za upotrebu, a koja se definiše modelom podataka. Smatra se da je postizanje veće kompatibilnosti između predstave koju korisnik ima o sistemu i načina na koji sistem zaista funkcioniše ključ za efikasno i efektivno korišćenje interaktivnih sistema. U tom smislu, podaci koji se u bazi mogu predstaviti u obliku zvezdaste sheme (dimenziono modelovani podaci), gde su veze između objekata i hijerarhijski odnosi načelno dati u okviru jednog objekta, i podaci koji imaju strukturu u kojoj je svaki hijerarhijski nivo predstavljen posebnim objektom (transakciono modelovani podaci), za individualne korisnike mogu biti u različitoj meri upotrebljivi. Brzina i tačnost obavljanja poslovnih zahteva putem dimenziono i transakciono modelovanih podataka može zavisiti, kako od vrste i složenosti zadatka, tako i od psiholoških osobenosti korisnika. Kognitivni stil, specifičan način kognitivnog funkcionisanja, izdvojio se kao relevantan faktor. S druge strane, isticanje sve većeg značaja afektivne komponente procene sistema i veze sa objektivnim merama upotrebljivosti, uticalo je na to da se u eksperimentalni nacrt uvrste i dimenzije emocionalnih reakcija na izgled sistema. U istraživanju su se, u dva modela podataka, ispitivale brzina i tačnost rada ispitanika sa u različitom stepenu izraženim metaforičnim, racionalnim i empiričnim kognitivnim stilom, a s obzirom na izazvane emocionalne reakcije pobuđenosti, prijatnosti i dominantnosti. U eksperimentu sa ponovljenim nacrtom učestvovalo je 303 ispitanika, slučajno raspoređenih s obzirom na redosled izlaganja modela podataka, i ujednačenih po karakteristikama relevantnim za Mr Ivana Kovačević – DOKTORSKA DISERTACIJA 2 istraživanje. Rezultati govore u prilog bolje upotrebljivosti dimenzionog modela u kom ispitanici brže obavljaju zadatke. Brzina i tačnost rada nisu u očekivanoj korelaciji i nejednako variraju s obzirom na različite prediktore, te ih je smisleno odvojeno posmatrati. Manipulativna varijabla redosleda izlaganja modela se pokazala najznačajnijim prediktorom brzine rada. Ispitanici postižu mnogo bolje rezultate ukoliko prvo koriste dimenzioni model, kao pojavno manje složen, nego u situaciji kada je transakcioni model prvo korišćen. Ovaj nalaz govori u prilog tome da je brzina rada zavisna od specifičnog redosleda iskustva. U skladu sa tim su i rezultati koji pokazuju da kognitivni stil nema naročitog efekta na brzinu rada, za razliku od emocionalnih reakcija prijatnosti i kontrole koje su negativno povezane sa potrebnim vremenom da se zadaci obave. S druge strane, tačnost je relativno nezavisna od redosleda izlaganja, i konzistentna karakteristika u oba modela. Ispitanici koji teže tačnosti, to čine bez obzira na prethodna ili trenutna iskustva, stoga se čini da je tačnost rada inherentna karakteristika korisnika. Tako su nađene i veze metaforičnosti, racionalnosti i empiričnosti sa tačnošću rada. Tačnost opada pri prelasku sa transakcionog na dimenzioni model podataka, u funkciji porasta metaforičnosti (moguć efekat zamora), dok se prelaskom sa dimenzionog na transakcioni, povećava u transakcionom u funkciji povećanja skora na racionalnosti (moguć efekat uvežbanosti). Empiričnost je povezana sa slabijom tačnošću rada u transakcionom modelu, kada je on prvi model u kom se radi (moguć efekat neuvežbanosti). Pojednostavljeno rečeno, ukoliko težimo efikasnosti (većoj brzini rada), insistiraćemo na jednostavnijim ili pak postupno usložnjavajućim interfejsima. Ukoliko težimo efektivnosti (većoj tačnosti rada), rešenja ćemo tražiti u personalizaciji korisničkih interfejsa.Informational compatibility of computer system and user, as the subject of cognitive ergonomics, depends on the characteristics of user interface. Well conceived user interface, with its structure and amount of information, provides optimal interaction in complex computer‐user system. Visual form of interface is based on logics in which data are displayed (arranged), interconnected and available for use, defined by data models. It is assumed that achieving higher compatibility between user perception of the system and the manner in which it really operates is the key for effectiveness and efficacy in using interactive systems. There are at least two different data base arrangements with different usability level for individual users. Dimensionally modeled data are arranged in a shape of star schema, where all relations between objects and all hierarchical associations are given within one object. Transactionallly modeled data have structure within which every hierarchical level is represented with particular object. Speed and accuracy of performing tasks by using dimensionally or transactionally modeled data are dependent on type and complexity of tasks, as well as on psychological characteristics of users. Cognitive style, as the specific manner of cognitive functioning, and dimensions of emotional reactions on system appearance, are seen as relevant factors. Research consisted of experimentally measuring the speed and accuracy of performing tasks in two data environments (dimensional and transactional data models) by participants with different levels of metaphorical, rational and empirical cognitive styles. Emotional reactions of arousal, pleasure and dominance provoked during the experience of using data models were assessed as well. In this experiment 303 participants, balanced by relevant characteristics, were randomly assigned in groups according to the order of exposing to data models. Results proved better overall performance of dimensionally modeled data Mr Ivana Kovačević – DOKTORSKA DISERTACIJA 4 which is seen as a data model with higher usability. Speed and accuracy of performance are shown not to be in expected correlation, varying differently according to the different predictors. Therefore, it was concluded it is plausible to consider them as separate entities. Manipulative variable, the order of data model display, proved to be the most important predictor of speed performance. Participants achieved better results when using dimensionally modeled data first, with its appearance less complex, than in situation when the transactional model was primarily used. This result showed that performance speed was dependent on specific order of user experience. Accordingly, it was found that cognitive style had no particular effect on speed, while emotional reactions of pleasure and dominance were negatively related to the time required for task completion. On the other hand, accuracy was relatively independent of data model order and it is a consistent characteristic within subject in both models. Participants who tended to be accurate, did that regardless of their previous or current experience with data model, thus it appeared that performance accuracy was user`s inherent quality. Relations between accuracy and metaphorical, rational and empirical cognitive styles were also found. Accuracy of dimensionally modeled data performance was poorer when using the transactional model first, in function of higher level of metaphorical style (possible effect of fatigue). Conversely, when using the dimensional model first, accuracy is higher in the transactional model in function of increasing the score on rational dimension (possible effect of training). Empirical cognitive style is correlated with lower accuracy in the transactional model, when it was a the first model of choice (possible effect of lack of practice). Generally, abridged implications of findings were the following, if we strive to achieve efficacy (speed), we should insist on simplifying, or at least gradually building more complexity in user interfaces. Otherwise, if we are looking for effectiveness (accuracy), we should try to find a solution in the personalization of user interface

Aggregation model for curtailable generation and sheddable loads

This paper shows modelling developed during the first year of the SmartNet project. In particular, it presents a mathematical model for aggregation of curtailable generation and sheddable loads. The model determines the quantity and the cost of the flexibility provided by the flexible resources based on their physical and dynamic behaviours. The model also proposes a bidding strategy in order to translate the aggregated behaviour into market bids