Parallel-strip line stub resonator for permittivity characterization

A new type of a microwave permittivity sensor with a short open stub as a resonator is introduced. The open stub is realized as a double-sided parallel-strip line without a substrate and can be totally immersed into the measured material. It provides high sensitivity of the resonant frequency nearly proportional to the ratio of square roots of dielectric constants of the measured materials. The sensor is tested in two different frequency ranges and for two different dielectric constant ranges (oils and ethanol-water mixture). Its technology is without any additional technological processes such as vias, air-bridges or defected ground structures. Presented sensor is designed, fabricated and tested showing good agreement between simulations and measurements

Cylindrical-parabolic reflector with printed antenna structures

The paper presents concept of design and realization of the new class of printed antenna structures which consist of a linear axial array of dipoles, subreflector, feed network and a bal-un, all printed on a common dielectric substrate. The array is positioned on the axis focus of the cylindrical-parabolic reflector. Use of the reflector enables reducing back side radiation and shaping beamwidth in H-plane thus obtaining higher gain while the printed subreflector gives the possibility of achieving additional gain. Besides, by using dipoles with pentagonal shape that operate on the second resonance, enhanced bandwidth of the array has been accomplished. Four variants of such arrays have been realized: two of them with 8 radiating elements for the frequency range around 26 GHz - one with uniform and the other with tapered feed distribution, featuring gains of 27.5 dBi and 25.7 dBi, respectively. The latter has the side lobe suppression of 28 dB in E-plane. Two other arrays that are intended for ranges around 23 GHz and 60 GHz have 16 radiating elements, uniform feed distribution and measured gains of 33 dBi and 34 dBi, respectively. Bandwidths of all realized model for S11 less than -10 dB is around 30 %. In all cases agreement between simulated and measured results is very good

The Development of Communicative Competence in Business English in Higher Education

Doktorska disertacija Razvoj komunikativnih kompetencija u nastavi poslovnog engleskog jezika u visokom obrazovanju bavi se ispitivanjem primene komunikativnog pristupa u nastavi poslovnog engleskog jezika i njenim uticajem na komunikativne kompetencije studenata. Cilj disertacije je najpre bio da utvrdi stavove studenata o upotrebi komunikativnog pristupa u nastavi poslovnog engleskog jezika, a zatim da istraži vezu između stavova studenata o komunikativnom pristupu i njihovih komunikativnih kompetencija. Ispitivan je i uticaj psihološko-društvenih i pedagoških faktora poput motivacije, anksioznosti i strategija koje studenti koriste prilikom učenja engleskog jezika na njihove komunikativne kompetencije. Pored ispitivanja veza između komunikativnih kompetencija studenata i njihovih stavova o komunikativnom pristupu, kao i veze između stepena motivisanosti, anksiznosti, upotrebe strategija prilikom učenja engleskog jezika i nivoa komunikativnih kompetencija studenata, cilj ove disertacije je bio i da izvrši analizu potreba studenata koja predstavlja polaznu tačku u izradi nastavnog plana i programa kurseva engleskog jezika za posebne namene, odnosno poslovnog engleskog jezika. Naime, analiza trenutne situacije i ciljne situacije omogućila je uvid u potrebe studenata na osnovu kojih su izvedeni zaključci koji potkrepljuju nalaze dobijene statističkom analizom i ujedno pružaju sugestije i implikacije za buduću nastavnu praksu. U istraživanju su korišćene mešovite metode i one uključuju: prikupljanje i analizu kvantitativnih podataka dobijenih na osnovu Opšteg upitnika, Upitnika o primeni komunikativnog pristupa, Upitnika o motivisanosti i anksioznosti studenata, Upitnika o strategijama učenja stranog jezika i Skale za procenu komunikativnih kompetencija studenata i njihovu statističku obradu (deskriptivna statistika, korelaciona analiza, distribucija frekvencija, regresiona analiza), prikupljanje i analizu kvalitativnih podataka tehnikom intervjuisanja i pisanjem dnevnika o učenju engleskog jezika i njihovu analizu. Triangulacija je izvršena integracijom kvalitativnih podataka sa kvantitativnim podacima tako da oni potkrepljuju dobijene nalaze. Istraživanje je sprovedeno na Visokoj poslovnoj školi strukovnih studija u Blacu u toku zimskog semestra akademske 2016/2017. godine, a kvantitativni uzorak predstavlja 43 studenata druge i treće godine studenata koji uče poslovni engleski jezik, dok kvalitativni uzorak dobijen na osnovu intervjua predstavlja 21 student, a na osnovu dnevnika 39 studenata. Dobijeni rezultati ukazuju da iako studenti preferiraju upotrebu pojedinih komunikativnih aktivnosti u nastavi poslovnog engleskog jezika, njihovi stavovi ne utiču na nivoe njihovih komunikativnih kompetencija. Naime, veza između stavova studenata prema komunikativnom pristupu i njihovih komunikativnih sposobnosti nije pronađena. Međutim, istraživanjem smo potvrdili da postoji određena povezanost između psihološko-društvenih i pedagoških faktora sa rezultatima na Skali za procenu komunikativne kompetencije. Drugim rečima, studenti koji su motivisani da uče engleski jezik ostvaruju bolje rezultate kada je komunikativna kompetencija u pitanju, kao i studenti kod kojih je anksioznost manje prisutna. Istraživanje je takođe pokazalo da je upotreba strategija kojima se studenti služe u učenju engleskog jezika veoma zastupljena i da povoljno utiče na nivoe njihovih komunikativnih kompetencija. Na kraju, regresionom analizom je utvrđeno da su glavni prediktori rezultata na Skali za procenu komunikativnih kompetencija studenata: dužina učenja engleskog jezika, samoprocena sposobnosti čitanja i razumevanja i upotreba metakognitivnih strategija u učenju engleskog jezika.The thesis The Development of Communicative Competence in Business English in Higher Education investigates the use of the communicative approach in teaching business English and its influence on students’ communicative competences. The aim of the thesis was primarily to determine the students’ attitudes about employing the communicative approach in teaching Business English and then to investigate the relationship between the students’ attitudes about the communicative approach and their communicative competence. The effects of psychological, social and pedagogical factors, such as motivation, anxiety and the language learning strategies on their communicative competence are examined as well. In addition to investigating the relationship between the students’ communicative competence and their attitudes about the communicative approach, as well as the relationship between the levels of motivation, anxiety and the use of language learning strategies and the levels of the students’ communicative competence, the aim of this thesis was to perform a needs analysis, which presents a starting point in the design of the teaching plan and program of English for Specific Purposes courses, that is for Business English courses. Namely, the current situation analysis and the target situation analysis have provided insights into the students’ needs which were used for making further conclusions which confirm certain results obtained by a statistical analysis and, at the same time, they provide suggestions and implications for future teaching practice. Mixed methods were applied in the research, including: collection and analysis of quantitative data obtained from the General questionnaire, Questionnaire about the use of the communicative approach, Questionnaire about students’ motivation and anxiety, Questionnaire about the use of language learning strategies and the Scale for assessing students’ communicative competences and their statistical analysis (descriptive statistics, correlational analysis, frequency distribution, regression analysis), qualitative data obtained by analysing interviews and students’ language learning diaries. Triangulation was performed by integrating qualitative and quantitative data in order to confirm the obtained results. The research was conducted at the Business School of Applied Studies in Blace, during the winter academic semester in 2016/2017. The quantitative sample is represented by 43 students of the second and the third year of studies who attend the Business English course, whereas the qualitative sample obtained from interviews is represented by 21 students and 39 students’ language learning diaries. The obtained results indicate that although the students prefer the use of certain communicative activities in Business English, their attitudes do not influence the levels of their communicative competences. Namely, the relationship between their attitudes about the communicative approach and their communicative competences was not found. However, this research confirmed the existence of a relationship between the psychological, social and pedagogical factors and the results on the Scale for assessing communicative competence. In other words, motivated students achieve better results in terms of their communicative competences, as well as the students with lower levels of anxiety. This research also confirmed that the use of language learning strategies is very dominant among students and that it positively influences their communicative competence levels. Finally, the regression analysis identified the main predictors of the results on the Scale for assessing communicative competence: the duration of learning English, the self-evaluation of the reading and understanding skills and the use of metacognitive language learning

Topography, morphology, vascularization and inervation of the abdominal organs in the mole rat (Spalax leucodon)

U relevantnoj literaturi ima malo podataka o topografiji, morfologiji, mikroskopskoj građi, vaskularizaciji i inervaciji organa trbušne duplje slepog kučeta (Spalax leucodon), pa smo zato odlučili da ispitamo trbušnu duplju, topografiju, morfologiju, vaskularizaciju i inervaciju trbušnog dela jednjaka (Pars abdominalis), želuca (Ventriculus), tankog creva (dvanaestopalačnog creva-Duodenum, praznog creva-Jejunum i vitog creva-Ileum), debelog creva (slepog creva-Cecum, kolona-Colon i pravog creva-Rectum), jetre (Hepar) i žučne kanale, slezine (Lien), gušterače (Pancreas) i bubrega (Ren). Ispitivali smo i topografiju i granjanje trbušne aorte (Aorta abdominalis), topografiju i pritoke kaudalne šuplje vene (V. cava caudalis) i vene ekstrahepatičnog dela portalnog krvotoka jetre. Rezultate našeg ispitivanja upotpunili smo opisom histološke građe trbušnog dela jednjaka, želuca, tankog creva, debelog creva, jetre, slezine, gušterače, bubrega, trbušne aorte i kaudalne šuplje vene. Kvantitativna analiza zida trbušne aorte i kolona vršena je linearnim i stereološkim merenjima pomoću mnogonamenskog test sistema M42. Kao material za izučavanje koristili smo organe trbušne duplje slepog kučeta (Spalax leucodon) sveže i konzervisane preparate iz kolekcije Katedre za anatomiju Fakulteta veterinarske medicine u Beogradu. Slepi kučići hvatani su na terenu Južnog Banata i to u mestu Šušara kod Uljme (Deliblatska peščara). Obzirom da je u Republici Srbiji slepo kuče zaštićeno zakonom kao prirodna retkost, dobili smo odobrenje Etičkog komiteta Fakulteta veterinarske medicine u Beogradu, dekana Fakulteta veterinarske medicine u Beogradu i Ministarstva zaštite životne sredine Republike Srbije za nabavku deset slepih kučića iz prirode. Za ispitivanje koristili smo anatomske, histološke, morfometrijske i stereološke metode rada. Uz obaveznu anesteziju primenom preparata ketamina (Ketamidor 10%) uz premedikaciju Ksilazinom, životinje su bile žrtvovane. Za morfološko ispitivanje preparati su posmatrani golim okom ili pod stonom lupom, uvećanje 1,75x...Data on morphology, topography, vascularization and innervation of the abdominal cavity organs of the mole rat (Spalax leucodon) published in the reference literature are scarce, and therefore we have decided to study abdominal cavity, topography, morphology, vascularization and innervation of the abdominal portion of the esophagus, stomach, small intestine (duodenum, jejunum and ileum), large intestine (cecum, colon and rectum), liver and its bile ducts, spleen, pancreas and kidneys. Topography and branches of the abdominal aorta, topography and tributaries of the caudal vena cava as well as extrahepatic veins of the portal system were studied as well. The results of our study were supplemented by description of the histological structure of the abdominal portion of the esophagus, stomach, small intestine, large intestine, liver, spleen, pancreas, kidneys, abdominal aorta and caudal vena cava. Quantitative analysis of the wall of the abdominal aorta and all parts of the colon was perfomed linear measurements and stereological measurement using test system M42. Abdominal cavity organs of the mole rat were used as material for investigation both as fresh and preserved preparations from the collection of the Department of Anatomy of the Faculty of Veterinary Medicine in Belgrade. Mole rats were traped on the area of south Banat in the village of Šušara near Uljma (Deliblatska peščara). Since mole rat is protected by law in Republic of Serbia as natural rarities, the approvals of the Ethics Committee and Dean,s of the Faculty of Veterinary Medicine in Belgrade as and Ministry of Environmental Protection of the Republic of Serbia were obtained for provision of 10 mole rats from their natural habitats..

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

Orijentacija starih pravoslavnih crkava u Republici Srbiji severno od Save i Dunava

This article presents the results of a mathematical-geographical analysis of the direction of ancient Orthodox churches in the Republic of Serbia north from the Sava and the Danube. These are medieval churches, or churches erected on the foundations of medieval churches, most of which katholikons, concentrated on the slopes of Fruška gora ('the Serbian Athos'). The main axes of all analysed churches (a total of 23) are located in the east sector of the horizon, i.e. they were all built according to the rule dictating that a church axis should be directed towards 'the rising sun'. The axes of four churches could not be directed towards the rising sun (towards the rising sun on the physical horizon). The axes of three churches are directed towards the equinox East, while the axes of the others, with one exception only, deviate towards NE (among which two with solstice direction). Based on the observed general deviation towards NE, it can be assumed that the church axes were directed, on their founding, towards the rising sun in spring, mostly around Annunciation.U članku su izloženi rezultati matematičko-geografske analize orijentacije starih pravoslavnih crkava u Republici Srbiji severno od Save i Dunava. To su srednjovekovne crkve, ili crkve podignute na mestu srednjovekovnih, uglavnom katolikoni, koncetrisane na padinama Fruške Gore ('Srpski Atos'). Glavne ose svih analiziranih crkava (ukupno 23) nalaze se u istočnom sektoru horizonta, tj. sve su izgrađene u skladu sa pravilom koje propisuje da bi osa crkve trebala biti usmerena 'ka izlasku sunca'. Ose četiri crkve nisu mogle biti usmerene prema izlazećem suncu (prema izlasku sunca na fizičkom horizontu). Ose tri crkve usmerene su ka ravnodnevačkom istoku, dok su ose ostalih, samo sa jednim izuzetkom, otklonjene ka NE (među njima dve sa solsticijskom orijentacijom). Na osnovu uočenog opšteg otklona ka NE, može se pretpostaviti da su ose crkava pri zasnivanju usmeravane ka izlazećem suncu na proleće, pretežno oko Blagovesti

Orijentacija starih pravoslavnih crkava u Republici Srbiji severno od Save i Dunava

This article presents the results of a mathematical-geographical analysis of the direction of ancient Orthodox churches in the Republic of Serbia north from the Sava and the Danube. These are medieval churches, or churches erected on the foundations of medieval churches, most of which katholikons, concentrated on the slopes of Fruška gora ('the Serbian Athos'). The main axes of all analysed churches (a total of 23) are located in the east sector of the horizon, i.e. they were all built according to the rule dictating that a church axis should be directed towards 'the rising sun'. The axes of four churches could not be directed towards the rising sun (towards the rising sun on the physical horizon). The axes of three churches are directed towards the equinox East, while the axes of the others, with one exception only, deviate towards NE (among which two with solstice direction). Based on the observed general deviation towards NE, it can be assumed that the church axes were directed, on their founding, towards the rising sun in spring, mostly around Annunciation.U članku su izloženi rezultati matematičko-geografske analize orijentacije starih pravoslavnih crkava u Republici Srbiji severno od Save i Dunava. To su srednjovekovne crkve, ili crkve podignute na mestu srednjovekovnih, uglavnom katolikoni, koncetrisane na padinama Fruške Gore ('Srpski Atos'). Glavne ose svih analiziranih crkava (ukupno 23) nalaze se u istočnom sektoru horizonta, tj. sve su izgrađene u skladu sa pravilom koje propisuje da bi osa crkve trebala biti usmerena 'ka izlasku sunca'. Ose četiri crkve nisu mogle biti usmerene prema izlazećem suncu (prema izlasku sunca na fizičkom horizontu). Ose tri crkve usmerene su ka ravnodnevačkom istoku, dok su ose ostalih, samo sa jednim izuzetkom, otklonjene ka NE (među njima dve sa solsticijskom orijentacijom). Na osnovu uočenog opšteg otklona ka NE, može se pretpostaviti da su ose crkava pri zasnivanju usmeravane ka izlazećem suncu na proleće, pretežno oko Blagovesti

Seed quantity and quality in fruit heads of Aster lanceolatus Willd.: Implications for invasion success

Aster lanceolatus Willd. is a herbaceous perennial that is considered invasive in many European countries. In Serbia, this plant inhabits wet habitats and forms widespread monospecific stands. The objective of this research is to determine whether generative reproduction has an important role in the expansion of this species to new areas. In 13 different localities, fruit heads were collected from lateral and terminal parts of infructescence. Seed quantity and germination parameters were determined for seeds in the fruit heads. The results showed that the position of the fruit heads did not have a major impact on germination parameters. However, germination parameters differed among the localities. The findings of this study suggest that A. lanceolatus produces a great amount of viable seeds that germinate in an amount sufficient to ensure a successful spread of this invasive species to new areas. [Projekat Ministarstva nauke Republike Srbije, br. 43007: Studying climate change and its influence on the environment: impacts, adaptation and mitigation

Cylindrical-parabolic reflector with printed antenna structures

The paper presents concept of design and realization of the new class of printed antenna structures which consist of a linear axial array of dipoles, subreflector, feed network and a bal-un, all printed on a common dielectric substrate. The array is positioned on the axis focus of the cylindrical-parabolic reflector. Use of the reflector enables reducing back side radiation and shaping beamwidth in H-plane thus obtaining higher gain while the printed subreflector gives the possibility of achieving additional gain. Besides, by using dipoles with pentagonal shape that operate on the second resonance, enhanced bandwidth of the array has been accomplished. Four variants of such arrays have been realized: two of them with 8 radiating elements for the frequency range around 26 GHz - one with uniform and the other with tapered feed distribution, featuring gains of 27.5 dBi and 25.7 dBi, respectively. The latter has the side lobe suppression of 28 dB in E-plane. Two other arrays that are intended for ranges around 23 GHz and 60 GHz have 16 radiating elements, uniform feed distribution and measured gains of 33 dBi and 34 dBi, respectively. Bandwidths of all realized model for S11 less than -10 dB is around 30 %. In all cases agreement between simulated and measured results is very good

Cylindrical-parabolic reflector with printed antenna structures

The paper presents concept of design and realization of the new class of printed antenna structures which consist of a linear axial array of dipoles, subreflector, feed network and a bal-un, all printed on a common dielectric substrate. The array is positioned on the axis focus of the cylindrical-parabolic reflector. Use of the reflector enables reducing back side radiation and shaping beamwidth in H-plane thus obtaining higher gain while the printed subreflector gives the possibility of achieving additional gain. Besides, by using dipoles with pentagonal shape that operate on the second resonance, enhanced bandwidth of the array has been accomplished. Four variants of such arrays have been realized: two of them with 8 radiating elements for the frequency range around 26 GHz - one with uniform and the other with tapered feed distribution, featuring gains of 27.5 dBi and 25.7 dBi, respectively. The latter has the side lobe suppression of 28 dB in E-plane. Two other arrays that are intended for ranges around 23 GHz and 60 GHz have 16 radiating elements, uniform feed distribution and measured gains of 33 dBi and 34 dBi, respectively. Bandwidths of all realized model for S11 less than -10 dB is around 30 %. In all cases agreement between simulated and measured results is very good