Influence of current reuse LNA circuit parameters on its noise figure

A 2.4 GHz low noise amplifier (LNA) with a bias current reuse technique is proposed in this work. To obtain the optimum noise figure (NF) value, dependence of NF on its most influential LNA parameters has been analyzed. Taking into account the LNA design requirements for other figures of merit, values of the circuit parameters are given for the optimum noise figure

Unfolding the assessment process in a whole class mathematics setting

Aktivnosti ocenjivanja na času predstavljaju važan aspekt prakse u učionici. U isto vreme, debata o prednostima i značaju formativnog ocenjivanja spram sumativnog i dalje se nastavlja. Ocenjivanje se ne odvija izvan okvira svakodnevne prakse u učionici, pa se, samim tim, na ocenjivanje gleda kao veoma kompleksan proces. U ovom radu želimo da istražimo način na koji se ocenjivanje stavlja u službu učenja učenika i da li se informacije koje nastavnik kroz ocenjivanje prikuplja koriste (ili ne) kako bi se svakodnevna praksa nastavnika u nastavi matematike prilagodila raznovrsnim potrebama učenika. Za potrebe ovog rada autori su pratili nastavnu praksu iskusnog nastavnika matematike u jednoj gimnaziji u Beogradu. Prakse ocenjivanja nastavnika posmatrane su u periodu od tri nedelje. Analiza pokazuje da nastavnik poseduje kompleksnu predstavu o tome kako ocenjivanje u učionici treba da izgleda, ali je percepcija toga u velikoj meri odvojena od nastave, što je u skladu s prethodnim nalazima. Međutim, elementi formativnog ocenjivanja se pojavljuju, pa doprinose tome da se ocenjivanje nađe u službi učenja. Uprkos tome, kada se pobliže posmatra način na koji nastavnik prati napredak učenika, evidentiran je ograničen skup praksi. Uočen je i nesklad između percepcija učenika i nastavnika u vezi s procesom ocenjivanja i primenjenim praksama. Takođe, nastavnik se suočava s teškoćama kada treba da verbalizuje neke od aspekata sopstvene prakse, naročito ako se oni vezuju za formativne karakteristike procene postgnuća učenika. PR Projekat Ministarstva nauke Republike Srbije, br. 179034 i br. 179018. .Assessment activities in the class are an important aspect of classroom practice, while there is much debate with respect to the formative vs. summative assessment routines and the outcomes that each of them provides for students' learning. As classroom assessment does not occur in seclusion of other aspects of classroom life, the process is seen as rather complex. In this study we wished to explore how assessment serves the function of supporting students' learning and whether this evidence is used to adapt teacher's practices in meeting different learning needs in the mathematics classroom. The authors observed assessment practices of an experienced math teacher in a grammar school in Belgrade. Teacher's assessment practices were observed during a three week period. The analysis has shown the teacher to hold a somewhat complex perception of assessment, yet the perception is largely detached from teaching, which is in line with the previously reported results. However, the elements of formative assessment do emerge, thus contributing to the assessment being in service of learning. In spite of this, a narrow set of practices are visible when observing how the teacher keeps track of students' progress. A mismatch is visible between students' and teacher's perceptions of the assessment as a whole and some of the practices exercised in the process. The teacher struggled to verbalize some aspects of own assessment practices, especially those related to more formative aspects

Yields of ZP sweet maize hybrids in dependence on sowing densities

Sweet maize differs from maize of standard grain quality by many important traits that affect the ear appearance, and especially by traits controlling taste. The ear appearance trait encompasses the kernel row number, configuration, row pattern (direction and arrangement), seed set, kernel width and depth, ear shape and size. The quality of immature kernels is controlled by genes by which sweet maize differs from common maize. In order to obtain high-ranking and high-quality yields, it is necessary to provide the most suitable cropping practices for sweet maize hybrids developed at the Maize Research Institute, Zemun Polje. The adequate sowing density is one of more important elements of correct cropping practices. The objective of the present study was to determine the effect of four sowing densities in four ZP sweet maize hybrids of different FAO maturity groups on ear qualitative traits and yields obtained on chernozem type of soil in Zemun Polje. The observed traits of sweet maize (ear length, kernel row number, number of kernels per row, yield and shelling percentage) significantly varied over years. The higher sowing density was the higher yield of sweet maize was, hence the highest ear yield of 9.67 t ha-1 , on the average for all four hybrids, was recorded at the highest sowing density of 70,000 plants ha-1. The highest yield was detected in the hybrid ZP 424su. The highest shelling percentage (67.81%) was found in the hybrid ZP 521su at the sowing density of 60,000 plants ha-1. Generally, it can be stated that sweet maize hybrids of a shorter growing season (FAO 400) could be cultivated up to 70,000 plants ha-1, while those of a longer growing season (FAO 500) could be grown up to 60,000 plants ha-1. In such a way, the most favorable parameters of yields and the highest yields can be obtained

Mathematics related anxiety: Mathematics bogeyman or not?

Podaci PISA testiranja iz 2003. godine ukazuju na visok nivo matematičke anksioznosti učenika u Srbiji. Više od polovine naših učenika brine da će imati teškoće na časovima matematike i da će dobiti loše ocene. Ciljevi ovog istraživanja jesu: ispitivanje veza između matematičke anksioznosti i postignuća na skali matematičke pismenosti; utvrđivanje mogućih prediktora matematičke anksioznosti i identifikovanje grupa učenika koje se razlikuju u njihovom odnosu prema matematici. Matematička anksioznost je u statistički značajnoj negativnoj korelaciji i sa školskim postignućem i sa postignućem na skali matematičke pismenosti. Sociodemografski faktori, motivacioni i kognitivni aspekti učenja matematike, doživljaj školske klime i klime na času objašnjavaju 40% varijanse matematičke anksioznosti. Na osnovu odnosa prema matematici učenici se mogu svrstati u tri grupe; dimenzije koje ih razdvajaju jesu nezainteresovanost -zainteresovanost i prisustvo - odsustvo anksioznosti. Grupa koja pokazuje anksioznost ima najlošije postignuće. Primenom kvalitativne analize ispitivani su stavovi učenika i nastavnika o specifičnim problemima u vezi sa nastavom i savlađivanjem gradiva iz matematike.Data of the PISA 2003 survey indicate high levels of mathematics anxiety of students in Serbia. More than half of our students worry whether they will have difficulties in mathematics class or whether they will earn poor marks. Aims of this study therefore are: examining relationship between math anxiety and achievement at mathematics literacy scale; establishing possible predictors of math anxiety and identification of students' groups in relations to their relationship towards mathematics as a subject. Mathematics anxiety is statistically negatively correlated with school achievement and achievement at mathematics literacy scale. Socio-demographic factors, motivational and cognitive aspects related to learning mathematics, perception of school and classroom climate explain 40% variance of mathematics anxiety. Based on students' relationship towards mathematics they cam be divided into three groups; while dimensions that apart them are uninterested-interested in mathematics and presence-absence of anxiety. The group displaying anxiety scores lowest among the three. Applying qualitative analysis students' and teachers' attitudes on specific issues related to teaching and learning mathematics was examined

Educational activities of secondary school students in Serbia: A time-diary analysis

Cilj istraživanja je da utvrdimo koliko su različite obrazovne aktivnosti zastupljene u strukturi tipičnog dana srednjoškolaca u Srbiji, kao i da li u tom pogledu postoje značajne razlike u zavisnosti od njihovih sociodemografskih karakteristika. Primenjena je metoda 24-časovnog vremenskog dnevnika. Istraživanje je obavljeno na uzorku od 922 učenika srednjih škola, strukturisanom po regionu, uzrastu i tipu škole. Analiza je pokazala da radnim danima srednjoškolci u proseku provode oko 5 sati u školi. U radnim aktivnostima van škole provode skoro 2 sata, od čega najveći deo u učenju (81 minut), a značajno manje u kućnim poslovima (23 minuta) i radu koji donosi prihode (7 minuta). Od ukupno 5 sati i 22 minuta slobodnog vremena, svega 5 minuta posvećeno je organizovanim vannastavnim aktivnostima. Utvrđene su značajne razlike u zastupljenosti obrazovnih aktivnosti u zavisnosti od pola, tipa škole i obrazovanja roditelja. Poređenje sa nalazima iz drugih zemalja ukazuje na neke kulturološke specifičnosti naših srednjoškolaca: u odnosu na srednjoškolce iz Sjedinjenih Američkih Država, oni provode značajno više vremena u učenju, a značajno manje u ekonomski produktivnom radu i kućnim poslovima, slično kao i mladi iz evropskih zemalja. Veoma mala zastupljenost vannastavnih aktivnosti pokazuje da je školsko učenje gotovo jedini kontekst razvoja obrazovnih kompetencija. Implikacije ovih nalaza razmatrane su iz perspektive pozitivnog razvoja mladih.The aim of this study was to determine the time allocation of various educational activities within the structure of a typical day of Serbian secondary school students, and whether there were significant differences in this respect depending on their socio-demographic characteristics. The 24-hour time diary method was applied: the subjects described chronologically, at half-hourly intervals, their activities in one weekday an done weekend day. The research was conducted on a sample of922 sec­ondary school students, Structured by region, age and type of school. The analysis revealed that on weekdays students spent about 5 hours in school. In work activities outside school they spent almost 2 hours, out of which the largest part in learning (81 minutes), and significantly less in housework (23 minutes) and economically productive work (7 minutes). From a total of5 hours and22 minutes of free time, only 5 minutes were devoted to organized extracurricular activities. Significant differences were obtained with regard to students' gender, type of school, and level of parents' education. When these results are compared with the data from other countries, it is shown that secondary school students in Serbia, compared to the U.S., spend more time in learning, and significantly less in economically productive work and house­work, much like the youth in European countries. A very low proportion of extracurricular activities shows that school learning is almost the only context of developing educational competencies. The implications of these findings are discussed from the perspective of positive youth development

Problems of Serbian youth: Growing up within the context of social crisis

Cilj ovog istraživanja bio je da utvrdimo sa kojim se problemima suočavaju mladi u Srbiji i kako procenjuju njihovu težinu, kao i da li postoje razlike u zavisnosti od pola, uzrasta, tipa škole i dela Srbije u kome mladi žive. Zanimalo nas je i da li su problemi, tipični za adolescentni uzrast i globalne društvene promene, pojačani odrastanjem u uslovima duboke ekonomske krize i tranzicije. Istraživanje je obavljeno 2007. godine, na uzorku od 2419 mladih, stratifikovanom po regionu (Beograd, Severna, Centralna i Južna Srbija), uzrastu (od prvog do četvrtog razreda srednje škole) i tipu škole (gimnazije i srednje stručne škole). Korišćen je upitnik konstruisan za potrebe ovog istraživanja. Rezultati pokazuju da većinu ispitivanih problema mladi ne doživljavaju kao velike ili posebno ugrožavajuće. Tri problema najviše brinu mlade, u smislu da ih više od trećine doživljava kao veće ili velike probleme: malo zanimljivih mesta za izlaske (46%), nedostatak slobodnog vremena (41%) i dosada (35%). Iznenađujuće mali broj mladih ima ozbiljnijih problema u odnosu sa roditeljima (22%) i vršnjacima (14%). Devojke i stariji srednjoškolci dosledno procenjuju skoro sve razmatrane probleme kao teže. Generalni zaključak je da dobijena slika nije onespokojavajuća, čemu verovatno najviše doprinose lepota, energija i optimizam same mladosti, kao životnog doba.Objective of this research was to identify problems that young people in Serbia have been dealing with, also how they perceive the weight of these problems and whether there are the gender, age, school type and regional differences in their perception of problems. We were also interested to find out if problems typical of adolescence, as well as problems characterizing some global social changes are intensified within the context of prolonged social crisis and transition. Research was conducted in October 2007, on a sample of 2419 young people, stratified by the region (Belgrade, North Central and South Serbia), age (first to fourth grade of secondary school) and school type (gymnasium, three years and four years vocational schools). An original questionnaire, constructed for this research, was applied. Results have shown that the majority of investigated problems have not been perceived as particularly big or harmful ones. Young people are most concerned with three problems (meaning that one third or more of youngsters find them to be big or relatively big ones): the lack of interesting places to go out (46%), the lack of time for leisure activities (41%) and boredom (35%). Surpassingly few youngster reported to have bigger problems with their parents (22%) or peers (14%). Girls and senior high school students systematically perceive almost all problems as harder ones. We could conclude that the gained picture was not gloomy, as it was expected, which could probably be attributed to joy, energy and optimism of these young people in this life span period

Psycho-social context of teenage alcohol abuse

Uvod. Pijenje mladih nema isti smisao kao pijenje starijih. Za mlade to je oblik osvajanja zrelosti i distinktivna osobenost, u vršnjačkoj grupi visoko vrednovanog, životnog stila. Iz perspektive mladih, problem imaju ne oni koji piju već oni koji ne piju. Cilj rada. Ispitali smo: prvo, koliko često se srednjoškolci opijaju (prema samooceni i prema proceni vršnjaka iz odeljenja) i, drugo, sa kojim faktorima je povezana sklonost mladih ka opijanju. Metod rada. Zadata su dva upitnika. Ispitano je 1745 učenika uzrasta od drugog do četvrtog razreda iz svih tipova srednjih škola. Ispitivanjem je obuhvaćeno 25 škola iz 9 gradova Srbije ravnomerno regionalno raspoređenih. Rezultati. Prema sopstvenom priznanju, više od dva puta se opilo 58% srednjoškolaca dok se prema procenama vršnjaka opija najmanje 42% učenika a možda i više. Mladići se opijaju više od devojaka, stariji više nego mlađi. Učenici koji se više opijaju imaju lošiji odnos sa roditeljima (p lt .00), subotom provode manje vremena sa porodicom (p lt .02), takođe, imaju više problema sa nastavnicima i sa učenjem (p lt .00). Mladi iz ove grupe zadovoljniji su odnosom sa bliskim vršnjacima (p lt .01) i među njima nalaze osobu na koju mogu da se oslone (p lt .00). Opterećenost ličnim problemima ne razlikuje se u ove dve grupe. Zaključak. Broj mladih koji se opijaju je zabrinjavajuće velik pogotovo kada se ima u vidu velika kulturna tolerancija prema piću. Naši podaci potvrđuju pretpostavku da pijenje ima važnu ulogu u socijalnom životu mladih jer su mladi koji piju čvršće vezani za vršnjačku grupu od onih koji ne piju. Sledstveno, njihovi odnosi sa svetom odraslih su ređi i konfliktniji. Podaci ukazuju na to da je važno da odrasli ne ustuknu pred snažnim magnetizmom vršnjačke grupe jer je prisustvo odraslih u životima mladih glavna zaštita mladih od zabavnog ali veoma rizičnog nemira vršnjačke grupe.Introduction. Youth drinking has a different meaning that drinking at an older age. For youth, it is a form of conquering maturity and a trait of distinction, a lifestyle highly valued by peers. From the youth perspective, the problem is with those who do not drink, not those who do. Objective. We surveyed first, the frequency of alcohol abuse among high school students (self-assessment and classmate assessment), and second, factors related to the tendency for alcohol abuse in youth. Method. Two questionnaires were developed for 1745 pupils in grades 10-12 of all types of secondary schools. The survey covered 25 schools from 9 evenly distributed Serbian cities. Results. 58% of pupils declare they have been drunk more than twice, while peer assessments suggest at least 41% of pupils abuse alcohol - boys more than girls, older students more than younger ones. Students more prone to alcohol abuse have a worse relationship with parents (p lt .00), spend less time with families on Saturdays (p lt .02), and have more problems with teachers and studying (p lt .00). They are satisfied with their relations with close peers (p lt .01) and find reliable persons among them (p lt .00). Experience of personal problems is the same in these two groups. Conclusion. The number of young people abusing alcohol is disturbingly high, especially given the obvious culture of tolerance for drinking. Our data confirm the assumption that drinking plays an important role in youth social life, manifested in stronger bonds with peer groups. Consequently, their relations with the world of adults are less frequent and more confrontational. Data indicate the importance of adults not retreating before peer group magnetism, since adult presence in the lives of young people is key to their protection from the fun but highly risky unrest of the peer group

Stručni saradnici škola o dobrobiti adolescenata na hraniteljskom smeštaju

Koncept dobrobiti, dobrostanja ili blagostanja (engl. well-being) upućuje na pozitivne karakteristike i optimalno funkcionisanje pojedinca tokom čitavog životnog ciklusa, a posebno je pogodn kao teorijski okvir za razmatranje razvoja dece i mladih. Ovo je složen koncept koji obuhvata: objektivne mere dobrobiti i životnih uslova dece i adolescenata; subjektivni doživljaj dobrobiti dece i adolescenata, njihova iskustva, gledišta, procene i aspiracije; iskustva, gledišta, procene i aspiracije drugih relevantnih aktera (roditelja i/ili drugih odgajatelja, nastavnika i stručnjaka) u pogledu dobrobiti dece i adolescenata (Ben Arieh et al., 2014). Ovako, sveobuhvatno određen, koncept dobrobiti naročito je primeren okvir za sagledavanje položaja i potreba defavorizovane i osetljive grupe dece i adolescenata na porodičnom semeštaju (Auerswald et al., 2017).XXVI Nаučnа konferencijа „Pedаgoškа istrаživаnjа i školskа prаksа

How high-schoolers perceive educational activities: A qualitative analysis of time recordings

Način na koji mladi doživljavaju obrazovne aktivnosti važan je ne samo za razumevanje razvojnih procesa koji se dešavaju u kontekstu tih aktivnosti, već i njihovih razvojnih efekata. Zato smo želeli da nalaze o količini vremena koje srednjoškolci provode u obrazovnim aktivnostima dopunimo podacima o tome kako oni doživljavaju rad u školi i učenje kod kuće, i to u pogledu mentalne zahtevnosti, motivacione vrednosti i ciljeva/značaja ovih aktivnosti. Spontani opisi učenika prikupljeni su metodom 24-časovnog vremenskog dnevnika, a obrađeni metodom analize sadržaja. Istraživanje je obavljeno na uzorku od 922 učenika srednjih škola, strukturisanom po regionu, uzrastu i tipu škole. Analiza je pokazala da srednjoškolci uglavnom doživljavaju obrazovne aktivnosti kao mentalno zahtevne i naporne, ali ne i kao izazovne i motivišuće, dok njihove ciljeve i značaj opažaju skoro isključivo instrumentalno. Ne tako mali broj pozitivnih komentara pokazuje da određene teme (predmeti) i nastavne aktivnosti (nastavnici) uspevaju da podstaknu unutrašnju motivaciju učenika, kao i da su školska postignuća značajan izvor njihovog doživljaja kompetentnosti i samovrednovanja. Pedagoške implikacije nalaza razmatrane su iz perspektive pozitivnog razvoja mladih i uticaja učeničkog doživljaja na obrazovna postignuća.The way the young perceive educational activities is important not only for understanding the developmental processes that take place in the context of these activities, but also their developmental effects. That is why we wanted to supplement the findings about the quantity of time that high-schoolers spend in educational activities with the data how they perceive their activities at school and studying at home, considering mental requirements, motivational values and aims/importance of these activities. Spontaneous descriptions of the students, compiled by the method of keeping 24-hour diary were analyzed by the method of content analysis. The research included 922 high school students, divided into groups according to the region, age and the type of the school. The analysis showed that high-schoolers perceive educational activities mainly as mentally demanding and tedious, not as challenging and motivating, while their aims and importance they see exclusively from the instrumental point of view. Not a small number of positive comments indicate that some themes (school subjects) and educational activities (teachers) succeed to stimulate intrinsic motivation, and that academic attainments are significant sources of their sense of competence and self-respect. Pedagogic implications of the findings were considered from the perspective of positive development of the young and the influence of the students' experiences upon academic achievements

Leisure and positive development of youth: The time use analysis

Cilj ovog istraživanja je da ispitamo kako mladi u Srbiji koriste slobodno vreme i koliko su njihove aktivnosti podsticajne sa stanovišta pozitivnog razvoja. Analizirali smo količinu vremena koju mladi dnevno provode u različitim kategorijama aktivnosti, zasnovanim na stepenu mentalnog i fizičkog angažovanja, primarnom cilju aktivnosti i stepenu strukturisanosti. Primenjena je metoda 24-časovnog vremenskog dnevnika: ispitanici su hronološki, po polučasovnim intervalima, opisali svoje aktivnosti tokom jednog radnog dana i jednog dana vikenda. U analizi podataka korišćen je pristup zasnovan na rekonstrukciji tipičnog dana. Istraživanje je obavljeno na reprezentativnom uzorku srednjoškolaca u Srbiji (N=922), stratifikovanom po regionu, uzrastu i tipu škole. Analiza je pokazala da mladi provode najveći deo slobodnog vremena u aktivnostima koje ne zahtevaju posebno mentalno ili fizičko angažovanje. U hipotetičkom danu naših tinejdžera, najviše su zastupljene aktivnosti kojima je cilj zabava i relaksacija, kao i nestrukturuisano druženje sa vršnjacima. Veoma malo su zastupljene individualne ili organizovane aktivnosti, usmerene ka aktualizaciji stvaralačkih potencijala i razvoju interesovanja i kompetencija (sekcije, hobi, volontiranje, itd.). Primetno je i da mladi provode najveći deo slobodnog vremena u nestrukturisanim aktivnostima, bez nadzora i sistematskog vođenja od strane odraslih. Verujemo da je deprimirajuća slika o slobodnom vremenu naših srednjoškolaca bar delom posledica nedovoljne sociokulturne podrške razvojno podsticajnijim načinima korišćenja vremena, u vidu organizovanih aktivnosti u školi i zajednici.The aim of this study was to examine how young people in Serbia are using free time and how their activities are beneficial, from the standpoint of a positive development. We have analyzed the amount of time youth daily spend in a different categories of activities, based on the degree of mental and physical engagement, the primary purpose of the activities and the degree of structured ness. The 24-hour time diary method was applied: subjects chronologically described, at half-hourly intervals, their activities in one working and one weekend day. The data analysis was based on a typical day reconstruction approach. The research was conducted on a representative sample of high school students (N = 922), stratified by region, age and type of school. The analysis revealed that young people spend most of their leisure time in activities that do not require a particular mental or physical engagement. In a hypothetical average day of Serbian teenagers, the most represented activities are aimed at fun and relaxation, as well as unstructured socializing with peers. Far less time is spent in individual or organized activities, aimed at the actualization of creative potentials and development of interests and competencies (extracurricular activities, hobbies, volunteering, etc.). It is evident that young people spend most of their free time in unstructured activities, without supervision and systematic guidance by adults. We believe that a gloomy picture of youth leisure time could be, at least partly, attributed to the lack of socio-cultural support for more developmentally enriching ways of spending time, in the form of organized activities at school and in the community