Identification of Ultrafast Photophysical Pathways in Photoexcited Organic Heterojunctions

The exciton dissociation and charge separation occurring on subpicosecond time scales following the photoexcitation are studied in a model donor/acceptor heterojunction using a fully quantum approach. Higher-than-LUMO acceptor orbitals which are energetically aligned with the donor LUMO orbital participate in the ultrafast interfacial dynamics by creating photon-absorbing charge-bridging states in which charges are spatially separated and which can be directly photoexcited. Along with the states brought about by single-particle resonances, the two-particle (exciton) mixing gives rise to bridge states in which charges are delocalized. Bridge states open up a number of photophysical pathways that indirectly connect the initial donor states with states of spatially separated charges and compete with the efficient progressive deexcitation within the manifold of donor states. The diversity and efficiency of these photophysical pathways depend on a number of factors, such as the precise energy alignment of exciton states, the central frequency of the excitation, and the strength of carrier-phonon interaction.Comment: Final, published versio

Die Entwicklung von Bewegungsleistung der Volleybalispieler ohne Ball

Volleyball is a game that is played on a rather small court, demanding a considerable speed level of the top players. The speed in volleyball becomes apparent mostly in the performance of the technical-tactical elements and specific movements aiming at attacking quickly and efficiently (especially in a combination and feint attacks) or at covering optimally the largest possible part of the court in defense actions (block or field defense). By suggesting a number of exercises, the authors wish to draw attention to the development of the specific speed of volleyball players without the ball as well as to the specification and regularity of the technique of movements around the volleyball court (“backing off” the block to defense, defenders moving from Tempo 1 to Tempo 2 defense, “backing off” the net and run-up fora spike, etc.). A certain number of exercises suggest a different approach to the development of the specific speed in volleyball players (exercises stressing the “step hop” movements and “foot fire” exercises) and can by all means be considered a novelty in volleyball training. They are the result of empirical knowledge exclusively.Der Volleyball ist ein Mannschaftsballspiel, auf einem relativ kleinen Spielfeld gespielt, wobei von den Leistungssportler ein beneidenswertes Höchstmaß an Schnellbewegungen erwartet wird. Die Schnellbewegungen im Volleyball zeigen sich bei der Durchführung von technisch-taktischen Elementen und spezifischen Bewegungsarten aus, -wodurch beabsichtigt wird, den Angriff möglichst schnell und effektvoll zu machen (besonders im kombinatorischen und fintierten Angriff) oder optimal einen größeren Spielfeld beim Gegenangriff zu verteidigen (Blockade oder Feldverteidigung). Durch die vorgeschlagenen Übungen soll die Aufmerksamkeit auf spezifische Schnellbewegungen der Volleyballspieler ohne den Ball gelenkt werden wie auch auf die richtige Bewegungstechnik auf dem Spielfeld (Übergang von Blockade auf Feldverteidigung, Übergang von Feldverteidigung im Tempo I. zum Tempo IL, Übergang vom Netz und Aufschwung zum Schmetterschlag, u.a.)

Die Entwicklung von Bewegungsleistung der Volleybalispieler ohne Ball

Volleyball is a game that is played on a rather small court, demanding a considerable speed level of the top players. The speed in volleyball becomes apparent mostly in the performance of the technical-tactical elements and specific movements aiming at attacking quickly and efficiently (especially in a combination and feint attacks) or at covering optimally the largest possible part of the court in defense actions (block or field defense). By suggesting a number of exercises, the authors wish to draw attention to the development of the specific speed of volleyball players without the ball as well as to the specification and regularity of the technique of movements around the volleyball court (“backing off” the block to defense, defenders moving from Tempo 1 to Tempo 2 defense, “backing off” the net and run-up fora spike, etc.). A certain number of exercises suggest a different approach to the development of the specific speed in volleyball players (exercises stressing the “step hop” movements and “foot fire” exercises) and can by all means be considered a novelty in volleyball training. They are the result of empirical knowledge exclusively.Der Volleyball ist ein Mannschaftsballspiel, auf einem relativ kleinen Spielfeld gespielt, wobei von den Leistungssportler ein beneidenswertes Höchstmaß an Schnellbewegungen erwartet wird. Die Schnellbewegungen im Volleyball zeigen sich bei der Durchführung von technisch-taktischen Elementen und spezifischen Bewegungsarten aus, -wodurch beabsichtigt wird, den Angriff möglichst schnell und effektvoll zu machen (besonders im kombinatorischen und fintierten Angriff) oder optimal einen größeren Spielfeld beim Gegenangriff zu verteidigen (Blockade oder Feldverteidigung). Durch die vorgeschlagenen Übungen soll die Aufmerksamkeit auf spezifische Schnellbewegungen der Volleyballspieler ohne den Ball gelenkt werden wie auch auf die richtige Bewegungstechnik auf dem Spielfeld (Übergang von Blockade auf Feldverteidigung, Übergang von Feldverteidigung im Tempo I. zum Tempo IL, Übergang vom Netz und Aufschwung zum Schmetterschlag, u.a.)

Eksperimentalno i teorijsko ispitivanje mehanizma nastajanja fenilseleno-etara iz nekih terpenskih alkohola

Supstituisani tetrahidrofurani nalaze se kao strukturni fragmenti u širokom spektru prirodnih proizvoda i drugih biološki aktivnih molekula. Na primer, acetogenini su velika porodica prirodnih proizvoda koji imaju u svojoj strukturi tetrahidrofuranski prsten. Zbog značaja ovih molekula, značajan napor je usmeren ka razvoju novih metoda za sintezu tetrahidrofurana. Veoma važna metoda za dobijanje tetrahidrofuranskih derivata je reakcija fenilselenoeterifikacije olefina. Ciklofunkcionalizacija olefina koji sadrže i nukleofilni kiseonik sa selenskim reagensima poznata je kao fenilselenoeterifikacija. Ovo je sve više proučavana ciklizaciona reakcija koja je našla primenu u raznim granama hemije, a naročito se koristi u totalnim sintezama. Velika prednost ove reakcije je ta što se izvodi pri blagim reakcionim uslovima. Ovo nas je navelo da vršimo eksperimentalno i teorijsko ispitivanje fenilselenoeterifikacije terpenskih alkohola (linalol, nerolidol i α-terpineol). Rezultati dobijeni u detaljnom ispitivanju mehanizma fenilselenoeterifikacije terpenskih alkohola u prisustvu kiselih i baznih katalizatora biće predstavljeni sledećim redosledom: 1. Intramolekulska ciklizacija terpenskih alkohola sa organoselenskim reagensima (PhSeCl i PhSeBr) ispitivana je u prisustvu ekvimolarnih količina Lewis-ovih baza i kiselina kao aditiva. Prisustvo aditiva obezbeđuje brzu i efikasnu reakciju ciklizacije. Takođe, sprečava i pojavu sporednih proizvoda. Ciklični etar tetrahidrofuranskog tipa dobijen je u kvantitativnim prinosima u reakciji linalola i nerolidola. Tetrahidropiranski proizvod dobijen je u kvantitativnim prinosima u reakciji α-terpineola. 2. Kinetika fenilselenoeterifikacije linalola i nerolidola sa PhSeCl i PhSeBr u prisustvu Lewis-ovih baza praćena je UV-Vis spektrofotometrijski u tetrahidrofuranu. Sve reakcije su praćene kao reakcije pseudo-prvog reda. Vrednosti za konstante brzine ciklizacije pokazuju linearnu zavisnost u funkciji od baznosti upotrebljenog aditiva. 115 Najbrža reakcija je u pristvu piperidina koji je i najbazniji aditiv. Reakcije sa PhSeCl su brže nego one sa PhSeBr. 3. Mehanizam fenilselenoeterifikacije linalola i nerolidola je ispitan na molekulskom nivou. Primećeno je da je uticaj kontra jona na mehanizam fenilselenoeterifikacije veoma izražen. Ukoliko se kontra jon izostavi iz kvantno- hemijskih izračunavanja (a tako je rađeno sve do ove doktorske disertacije) dobija se lažna slika o mehanizmu reakcije, tj. da je syn put povoljniji od anti puta. Ova greška je posledica pogrešno izračunate energije solvatacije, koja u slučaju pozitivno naelektrisanih prereakcionih kompleksa ima nerealno velike vrednosti. Kada se kontra jon uključi u kvantno-hemijska izračunavanja (što je po prvi put učinjeno u ovoj doktorskoj disertaciji) proizilazi da je prvi korak reakcije (adicija fenilselenil grupe na dvostruku vezu terpenskog alkohola) endergoni proces koji se odvija preko prelaznog stanja. Nastali kontra joni vrše uticaj na pozitivno naelektrisani deo reakcionog sistema tako što podižu energije aktivacije u drugom reakcionom koraku (ciklizacija). Zaključuje se da je u prisustvu kontra jona anti ciklizacioni put favorizovan, jer zahteva nižu energiju aktivacije za korak koji određuje brzinu reakcije, tj. za ciklizacioni korak.The substituted tetrahydrofurans are as structural fragments in a wide range of natural products and other biologically active molecules. For example, acetogenins are a large family of natural products that have tetrahydrofuran ring in their structure. Because of the importance of these molecules, significant effort has been directed toward the development of new methods for the synthesis of tetrahydrofuran. A very important method for obtaining tetrahydrofurans derivatives is a reaction of olefins by henylselenoetherification. Cyclofunctionalization of the olefins that have nucleophilic oxygen with a selenium reagents is known as reaction of phenylselenoetherification. A reaction of cyclization is increasingly studied which has been found application in various branches of chemistry, especially used in a total synthesis. This reaction is performed under mild reaction conditions and this is a great advantage. This leads us to perform an experimental and theoretical investigations of phenylselenoetherification of terpenic alcohols (linalool, nerolidol and α-terpineol). The results obtained in a detailed examination of the mechanism of phenylselenoetherification of terpenic alcohols in the presence of acid and base catalysts will be presented in the following order: 1. The intramolecular cyclization of the terpenic alcohol with organoselenium reagents (PhSeCl and PhSeBr) was investigated in the presence of equimolar amounts of a Lewis bases and the acids as an additives. The presence of additives provides quick and efficient cyclization reaction. Also, it prevents the occurrence of side products. Cyclic ether of the tetrahydrofuran type was prepared in quantitative yields in the reaction of linalool and nerolidol. Product of tetrahydropyran was obtained in quantitative yields by reaction of α-terpineol. 2. Kinetics of phenylselenoetherification of linalool and nerolidol with PhSeCl and PhSeBr in the presence of a Lewis bases is monitored by UV-Vis spectrophotometry in tetrahydrofuran. All reactions were monitored as a pseudo-first order reaction. The values of the rate constants of cyclization show a linear dependence as a function of the alkalinity of used additives. 117 The reaction in the presence of piperidine, which is the most alkaline additive is the fastest. Reactions with PhSeCl are faster than PhSeBr. 3. Mechanism of phenylselenoetherification of linalool and nerolidol was examined at the molecular level. It was noted that the impact of counter-ions on the mechanism of phenylselenoetherification is very pronounced. If the counter ion is omitted from quantumchemical calculations (this is done until the end of this doctoral thesis) gives a false picture of the reaction mechanism, ie. a syn way is more favorable way than a anti. This error is due to incorrectly calculate the solvatation energy, which in the case of positively charged in reacation complex has unrealistically high values. When the counter ion involved in the quantum-chemical calculations (which was first done in this doctoral thesis) leads that the first step of the reaction (addition phenylselenyl groups on the double bond of the terpene alcohol) is endergonic process that takes place over a transitional state. The resulting counter-ions influence the positively charged part of the reaction system by raising the activation energy in the second reaction step (cyclization). It is concluded that the presence of counter-ions favored anti cyclization patway, because it requires a lower activation energy for the rate determining step of the reaction, ie. for a cyclization step

Diskriminanzanalyse der von einer Mannschaft gewonnenen und verlorenen Sätze in der italienischen a1 volleyball-liga - eine Fallstudie

Chain of factors determines success or failure in any sport match, but the measurable part of it is related to the indicators of efficient performance of technical-tactical elements or game phases during the matches. The sample consisting of 76 sets, obtained from 20 matches played by one team in Italian men\u27s A1 league, was used in this study to determine, on the basis of five play-specific situational parameters, the differences between the sets won and the sets lost. A discriminant analysis was used. The canonical discriminant function significantly differentiated between the sets won and the sets lost, at the level of significance p<0.00. The discriminant function was defined by the highest projection of the variable spike in the phase of attack, and by somewhat lower projections of the variables spike in the phase of counterattack, serve reception, block and serve.Uvod Promatranje i analiza odbojkaške igre najčešće se zasnivaju na procjenjivanju parametara situacijske učinkovitost dobivenih iz odbojkaškog zapisnika, stenograma utakmice, video zapisa ili računalnih programa. U odbojci su statistički podaci dobiveni na utakmicama vrhunskih ekipa često nedostupni i nepotpuni, pa se na njima ne mogu primjenjivati postupci inferencijalne statistike. Na sreću, danas u Europi mnoge reprezentacije koriste unificirani računalni program (Datavolley), pa tako i specijaliste-statističare za praćenje odbojkaške igre. Materijal i metode Uzorak entiteta činilo je 76 setova dobivenih u 20 utakmica talijanske A1 lige u sezoni 1999./2000. god. koje je odigrala momčad Zetaline (Padova) s ekipama: Brescial-Montichiari, Modena, Sisley-Treviso, Cosmogas-Forli, Del Monte-Ferrara, Maxicono-Parma, Piaggio-Roma, Tnt Alpitour-Cuneo, Lube-Macerata, Iveco-Palermo i Vallever-Ravenna. Podaci su prikupljeni specijaliziranim računalnim sustavom bilježenja sadržanim u programskoj podršci Datavolley Rel. 5.0 tvrtke DATAPROJECT. Na ordinalnoj skali od pet stupnjeva ocjenjivala se učinkovitost izvedbe situacijskih elemenata igre, odnosno odbojkaških faza: 1. SERVIS, 2. PRIJEM SERVISA, 3. SMEČ IZ NAPADA, 4. BLOK i 5. SMEČ IZ KONTRANAPADA. Prva dva stupnja označavaju negativnu realizaciju, npr. grešku i akciju koja donosi prednost protivniku, treći stupanj na skali označava izvođenje nakon kojeg se akcija nastavlja bez prednosti i za jednu ekipu, dok posljednja dva stupnja označavaju da je izvedba donijela prednost ili bod. Kriterijsku varijablu čini binarno definiran rezultat svakog pojedinog seta na utakmici (pobjeda ili poraz za momčad Zetaline). Ulazni podaci su frekvencije odbojkaških faza, a nakon što je svaka izvedba procijenjena na skali od pet stupnjeva, frekvencije su uvrštene u formulu. Takvim načinom računanja dobivamo numeričke vrijednosti na ordinalnoj skali za svaku od pet faza igre koje možemo koristiti kao podatke za statističku obradu. Rezultati i rasprava Iz podataka dobivenih deskriptivnom statistikom (tablica 1, dijagram 1) vidljivo je da su značajnije razlike po kriteriju dobivenih i izgubljenih setova postignute u varijablama SMEČ U FAZI NAPADA (3,99 dobiveni naspram 3,66 izgubljeni setovi), SMEČ U FAZI KONTRANAPADA (3,92 dobiveni prema 3,57 izgubljeni setovi) te u varijabli BLOK (2,84 dobiveni prema 2,56 izgubljeni setovi), najvjerojatnije zbog toga što se tim elementima igre osvaja najveći broj poena u setu. U tablici 2 prikazani su rezultati svojstvene vrijednosti, kanoničke korelacije, hi-kvadrat testa, broj stupnjeva slobode i razina značajnosti diskriminacijske funkcije. Iz dobivenih vrijednosti možemo ustvrditi da diskriminacijska funkcija značajno razlikuje dobivene od izgubljenih setova na razini značajnosti od 0.00 (p<0.00), uz relativno visoku kanoničku korelaciju (.58). Tablica 3 prikazuje korelacije varijabli s diskriminacijskom funkcijom i položaj centroida dobivenih i izgubljenih setova na diskriminacijskoj funkciji. Na negativnom polu diskriminacijske funkcije nalaze se izgubljeni, a na pozitivnom polu dobiveni setovi. Struktura diskriminacijske funkcije je bipolarna. Pozitivni pol definiraju sve varijable, dok se na negativnom polu nije smjestila nijedna varijabla. Najvećom projekcijom diskriminacijsku funkciju definira varijabla SMEČ U FAZI NAPADA (SMNAP), nešto nižom projekcijom varijable SMEČ U FAZI KONTRANAPADA (SMKNAP) i PRIJEM SERVISA (PRIJEM), dok najmanjim projekcijama funkciju definiraju BLOK i SERVIS. Slično je dobio i Marelić (1998). U ovom se istraživanju varijabla SMEČ U FAZI NAPADA (.71) pokazala kao najsnažnija prediktorska varijabla. Objašnjenje za tako veliku prediktivnost nalazimo u tome da se smeč u procesu napada većinom izvodi nakon idealnog prijema servisa nakon kojega je dizač u mogućnosti organizirati brz i kombinacijski napad koji otežava anticipaciju protivničke obrane, a time i pravovremeno formiranje protivničkog bloka. Ovome u prilog ide i činjenica da se u novom sustavu igre (RPS - rally point system) uspješnom realizacijom smeča u napadu osvaja bod, za razliku od starog sustava gdje se nakon smeča u napadu osvajala samo promjena servisa. SMEČ U FAZI KONTRANAPADA (.37) ima nešto manju vrijednost, vjerojatno zato što se, novim pravilima, skratilo vrijeme igre za poen. Razlog možda leži i u izuzetno opasnom skok servisu koji ima dva cilja: osvojiti poen ili otežati prijem servisa tako da se dvojnim ili trojnim blokom osvoji poen. Tek ako se servisom i blokom poen ne osvoji, a obrana polja «uhvati» protivnički napad, organizira se smeč za kontranapad. Nešto nižu statistički značajnu vrijednost ima varijabla PRIJEM (.33). Važnost prijema servisa među trenerima nije upitna, čak je težnja za što boljim odgovorom na opasne servise rezultirala time da je u pravila uveden novi igrač – specijalist samo za prijem servisa i smeča (libero). Varijable SERVIS (.25) i BLOK (.28) također su se pokazale statistički značajnima i prediktivnima. U setu se servisom u prosjeku postiže 1-2 poena, ali je uloga servisa poput uloge bijelih figura u šahu - njegovim «otvaranjem» diktiramo daljnji tijek igre. Ne samo da osvajanje poena servisom ima značajnu ulogu u stvaranju rezultata, već jednako tako i greška servisa. Prihvatljiv broj grešaka servisa kod uspješnih odbojkaških ekipa iznosi oko 3,5 poena po jednom setu (Marelić, 1998). To znači da na utakmici od pet setova ekipe prosječno smiju pogriješiti i u 15-ak servisa, a da još uvijek mogu ostvariti pobjedu. Blokom se prosječno postiže nešto više poena po setu nego servisom (oko 3-4), ali je uvođenje libera (precizniji prijem servisa i bolja organizacija napada) rezultiralo time da blokeri moraju često individualnim blokom parirati protivničkim smečerima, što smanjuje uspješnost bloka. Tablica 4 prikazuje rezultate klasificiranja dobivenih i izgubljenih setova momčadi Zetaline na temelju diskriminacijske funkcije. Od 50 izgubljenih setova, 38 je dobro klasificirano (82,61), dok je od 26 dobivenih setova, 18 dobro klasificirano (60). Zaključak Rezultati kanoničke diskriminacijske funkcija pokazuju značajne razlike između dobivenih i izgubljenih setova na razini značajnosti od p<0.00 uz kanoničku korelaciju (.58), te možemo ustvrditi da prediktorske varijable (servis, prijem, blok, smeč u procesu napada i smeč u procesu kontranapada) statistički značajno razlikuju dobivene od izgubljenih odbojkaških setova. Pozitivni pol definiraju sve varijable. Najvećom projekcijom diskriminacijsku funkciju definira varijabla smeč u procesu napada, nešto nižim projekcijama varijable smeč u procesu kontranapada i prijem servisa te najnižim projekcijama varijable blok i servis.Die Gründe eines erfolgreichen oder erfolglosen Spielresultats sind in einer Reihe von Faktoren zu suchen, aber der meßbare Teil ist mit einem Indikator der situationsbezogenen Effizienz der technischen Elemente, der Elemente der Taktik oder der Spielphasen im Laufe des Spiels verbunden. 76 von einer Mannschaft gespielten Sätzen aus 20 Volleyballspiele der italienischen A1 Liga für Männer wurden analysiert, um aufgrund von fünf situationsbezogenen spielspezifischen Parametern die Unterschiede festzustellen, zwischen den gewonnennen und verlorenen Sätzen. Um diese Unterschiede zu bestimmen wurde die Diskriminanzanalyse angewandt. Die kanonische Diskriminanzfunktion machte einen wesentlichen Unterschied zwischen den gewonnennen und verlorenen Sätzen; das Signifikanzniveau war p<0,00. Die Diskriminanzfunktion wurde mit der höchsten Projektion definiert durch die Variable Schmetterschlag in der Angriffsphase und mit etwas niedrigerer Projektion der folgenden Variablen: Schmetterschlag in der Gegenangriffsphase, Aufgabeannahme, Block und Aufgabe

THE RELATIONSHIP BETWEEN MAXIMAL STRENGTH, VERTICAL JUMP, ACCELERATION AND CHANGE OF DIRECTION PERFORMANCE

The goal of the present study was to explore the relationship between maximum strength, the vertical jump, acceleration and change of direction performance in healthy young male students. The sample of variables included the following variables: body mass (BM), one repetition maximum on the half-squat test (Squat 1RM), one repetition maximum normalized for body mass (Squat 1RM_rel), peak power during the concentric phase of countermovement jump (Ppeak CMJ), vertical jump height during CMJ (CMJ_H), time for the 20m sprint (20m Srint) and time for the agility T-Test (Agility T-Test). The relationship was tested with the Pearson Coefficient of linear correlation (r). The results showed significant correlation between body mass with Squat 1RM_rel and peak concentric power during CMJ (r=-.424, and r=.377, respectively). Peak concentric power during CMJ additionally has a significant correlation with the change of direction abilities, 20m sprint, and vertical jump height, (r=-.401; r=-.467; r=.656; p<0.05, respectively). Also, significant correlation was determined between the 20m Sprint and Agility T-Test (r=.443; r=-.570, respectively), and Agility T-Test vertical jump height (r=-.498).  The level of relationships between maximum strength, acceleration, COD and CMJ may be attributable to differences in the control and coordination of several muscle groups during execution of these tests

Gender differences and classification of police university students relating to joint tissue flexibility

Flexibility influences the amplitude of body parts movement and consequently the efficiency of physical activities which are an integral part of police officers training and professional duties. The aim of this study was to determine the level of flexibility in students of the University of Criminal Investigation and Police Studies (UCIPS), as well as the differences between genders and to establish the criteria for evaluation. The sample consisted of 121 participants, 51 female (age 20.2 ± 1.2 years) and 70 male students (age 20.3 ± 0.9 years). All participants were the second year students. A battery of tests for flexibility assessment included: Sideways Leg Splits (SsLS), Sideward Leg Splits right (SdLS right), Sideward Leg Splits left (SdLS_left), Single-Legged Knee Bend right (SLKB_right), Single-Legged Knee Bend left (SLKB_left), Lengthwise Leg Splits right (LLS_right), Lengthwise Leg Splits left (LLS_left), Sit and Reach (SR), and Shoulder Flexibility (SF). The existence of the differences between groups was determined by ANOVA, at the significance level of p < 0.05. The differences were found in tests SsLS (F = 11.459, p = 0.001), SdLS_right (F = 8.440, p = 0.004), SdLS_left (F = 5.502, p = 0.021), SLKB_left (F = 5.545, p = 0.025), LLS_right (F = 11.481, p = 0.001), LLS_left (F = 18.008, p = 0.000), SR (F = 7.886, p = 0.006) and SF (F = 25.447, p = 0.000). The obtained results indicated different flexibility levels between male and female students. In relation to martial arts and other athletes the UCIPS students had lower levels of flexibility. The applied percentage distribution results, including six different groups, could be used as a scale for assessment of the achieved level of flexibility in police university students

Uticaj deviznog kursa na konkurentnost izvoza

Savremeni ekonomski uslovi podigli su značaj poslovanja van sopstvenih granica. Niz specifičnosti koje sa sobom nosi međunarodno tržište doprinosi konstataciji da devizni kurs postaje jedna od najvažnijih cena u ekonomiji. Pored činjenice da se veliki broj ekonomskih teoretičara bavi ovom problematikom, još uvek nije pronađena teorija koja će biti prihvaćena od strane svih učesnika na međunarodnom tržištu, tj. još uvek postoje nesuglasice ekonomista oko načina formiranja i intenziteta promena deviznog kursa, o čemu svedoči veliki broj različitih režima deviznih kurseva. Uloga i ekonomska dejstva deviznog kursa će biti različita u zavisnosti od izabranog režima deviznog kursa. Uključenost neke zemlje na međunarodno tržište u velikoj meri zavisi od dostignutog nivoa međunarodne konkurentnosti njene privrede. Međunarodna konkurentnost, kao izuzetno složen i višedimenzionalni fenomen zavisi od velikog broja faktora. S obzirom na izabranu temu, težište će biti stavljeno na konkurentnost izvoza i politiku deviznog kursa kao jedan od (cenovnih) faktora koji mogu uticati na međunarodnu konkurentnost. Pored povećanja izvoza u prvoj deceniji 21. veka, po svim pokazateljima, konkurentnost srpske privrede je još uvek izuzetno niska (prisutan je i dalje veliki spoljnotrgovinski deficit). Svojom ekonomskom snagom, sa skoro zanemarljivim procentualnim učešćem u ukupnom svetskom izvozu, Srbija ne može uticati na formiranje svetskih cena čime vođenje politike deviznog kursa dinara dobija na značaju. Hiperinflatorna prošlost i nepoverenje u spostvenu valutu uticali su da izabrani režim deviznog kursa na početku posmatranog perioda odigra značajnu ulogu u postizanju makroekonomske stabilnosti. Međutim, to je u određenoj meri doprinosilo i realnoj apresijaciji dinara, što se negativno odražavalo na izvoz i vodilo gubitku konkurentnosti. Sa druge strane, podsticanje izvoza samo politikom deviznog kursa (realnom depresijacijom dinara), bez ikakvih strukturnih reformi realnog sektora ekonomije, dugoročno gledano će svakako imati negativne posledice. Velika uvozna zavisnost, visoka spoljna zaduženost, visok stepen evroizacije, ponovno oživljavanje inflatornih očekivanja i otežavanje socijalnog položaja velikog broja građana samo su neki od faktora koji idu u prilog činjenici da promena deviznog kursa dinara ne može biti jedino rešenje u pokušaju povećavanja konkurentnosti srpskog izvoza.Contemporary economic conditions stressed the importance of business beyond its own boundaries. The range of international market specifics contributes to the theory that exchange rate becomes one of the most important prices in economy. Beyond the fact that numerous economic theoreticians deal with the point in question, the theory which will be accepted by all international market participants has not still been invented, that is there are still a lot of disagreement between economists considering the way of exchange rate formation and intensity of exchange rate changes which results in a great number of different exchange rate regimes. Exchange rate role and economic impacts will be different depending on a chosen exchange rate regime. Inclusion of a country in international market depends to a great extent on reached level of international competitiveness of its own economy. International competitiveness as a very complex and multidimensional phenomenon depends on numerous factors. Considering the topic in question, a special attention will be paid to export competitiveness and exchange rate policy as one of (price) factors which can influence international competitiveness. Considering all indices and economic growth in the first decade of 21st century, Serbian economy competitiveness is still very low (because of huge foreign trade deficit). On no account Serbia with its own economic strength and its trifle percentage participation in overall world export can have an influence on world price formation which results in emphasizing the importance of pursuing the dinar exchange rate policy. Hyperinflation as a part of Serbian economic history and also mistrust of its own currency have influenced the fact that chosen exchange rate regime at the beginning of the observed period played the important role in achieving macroeconomic stability. However, that was the reason why dinar real appreciated which had a negative impact on export and also led to the loss of competitiveness. On the other hand, export prompting caused only by exchange rate policy (real dinar depreciation) without any structural reforms of real economic sector will have negative consequences in the long run. Huge import dependence, huge foreign debt, high degree of euroisation, repeated revival of inflation expectations and aggravation of many citizens’ social status are only some of the factors that prove the fact that change of dinar exchange rate cannot be the only solution in the process of attempting to increase Serbian export competitiveness