Monte Carlo simulation of positron transport in realistic gas filled systems

Napredak uređaja za akumulaciju i skladištenje pozitrona omogućava sve preciznija merenja preseka za interakciju pozitrona sa atomima i molekulima. Nedavno kompletirani setovi sudarnih podataka za molekule koji se najčešće javljaju u pozitronskim uređajima i primenama (najpre N2, CF4 i H2O ali i drugi) omogućili su detaljne simulacije transporta pozitrona u takvim sredinama, kao i detaljan opis uređaja koji se na njima baziraju. Osnovni cilj ove disertacije jeste da na osnovu izmerenih sudarnih podataka, pomoću računarskih Monte Karlo simulacija, detaljno analizira realne uređaje i sisteme ispunjene gasom koji svoju funkciju baziraju na elementarnim procesima u kojima učestvuju pozitroni. Disertacija se fokusira na tri konkretna sistema: pozitronski trap, kompresiju snopa pozitrona rotirajućim poljem i termalizaciju pozitrona u biološki relevantnoj sredini. Otkriće i razvoj pozitronskog (Surko) trapa početkom devedesetih godina, predstavlja prekretnicu u polju fizike niskoenergijskih pozitrona i dovelo je do velikog napretka u razumevanju interakcije niskoenergijskih pozitrona sa atomima i molekulima. Trapovi su omogućili akumulaciju velikog broja pozitrona (106-108), niske energije sa energijskom raspodelom koja odgovara sobnoj temperaturi ( <50 meV ) što omogućava formiranje intenzivnih snopova pozitrona sa precizno definisanom energijom. Kao takvi, pozitronski trapovi predstavljaju osnovi alat u brojnim eksperimentima poput merenja preseka za interakciju, proizvodnje antivodonika, proizvodnje i proučavanja pozitronijuma, pozitronske anihilacione spektroskopije i slično. Od trenutka kada je prvi put primenjen, princip rada i dizajn pozitronskog trapa se nije značajnije menjao i standardno je obezbeđivao efikasnost trapovanja od 10-20%. U zavisnosti od konkretne primene trapa, kroz empirijske pokušaje su optimizovani različiti parametri rada, kao što su: efikasnost trapovanja, vreme života akumuliranih pozitrona, maksimalna koncentracija pozitrona ili broj emitovanih sporih pozitrona u sekundi. U disertaciji koristimo preseke koji su izmereni zahvaljujući ovakvim trapovima, kako bismo kroz simulaciju analizirali njihov rad, identifikovali procese koji utiču na performanse trapa i našli način da se performanse optimizuju. Ujedno, simulacija omogućava lakše menjanje osobina trapa koje nije lako promeniti u eksperimentu, kao što su geometrija trapa, ili sastav gasa. Kako simulacija identifikuje proces formiranja pozitronijuma na molekulima N2 kao glavni ograničavajući faktor za ostvarivanje veće efikasnosti, predložen je model, i urađena je detaljna simulacija alternativnog načina trapovanja pozitrona koja kao glavni radni gas umesto N2, za trapovanje koristi vibracione eksitacije molekula CF4, u energijskom opsegu daleko ispod praga za formiranje pozitronijuma. U saradnji sa kolegama sa University College London, iz Grupe za atomsku, molekulsku, optičku i pozitronsku fiziku, pokušana je konverzija standardnog pozitronskog trapa u predloženu CF4 konfiguraciju i utvrđeni su, kroz eksperiment i simulaciju, konstrukcijski nedostaci koji onemogućavaju konverziju najvećeg broja postojećih trapova, kao i aspekti koji bi trebalo da se uzmu u obzir prilikom konstrukcije budućih trapova...Development and advancement of positron accumulation and storage devices has enabled increaesingly accurate measurements of cross-sections for positron interaction with atoms and molecules..

Music in Serbian documentary prose in the second half of the 19th century ; Музыка в сербский документально-художественной прозы второй половины 19. века

У раду су документарно-уметничка остварења друге половине 19. века, из пера истакнутих српских културних посленика, књижевника, уметника, државника, новинара и политичара, сагледана као драгоцена грађа за упознавање токова и веза између српске културне и музичке историје. Аналитички су обрађене доминантне врсте из наведене области: мемоари, дневници, аутобиографије и путописи, као и одабрани биографски списи о знаменитим појединцима овог периода. Извори потврђују да је музика, у сфери јавног и приватног, била важан сегмент живота свих слојева српског друштва 19. века, у сложеним геополитичким и културноисторијским контекстима. У дијахроној перспективи, истражени материјал одсликава динамику и еволуцију облика и видова присуства музике и музичког живота у свим срединама насељеним српским живљем у овом периоду: у Хабзбуршкој монархији, Кнежевини и Краљевини Србији, као и у српским енклавама у другим националним срединама. Потврђено је да су међу кључним одликама различитих културних модела, карактеристичних за период културног плурализма међу Србима у 19. веку, музичка кретања заузимала посебно место у изградњи друштвене сфере и рецепције целокупне стварности...In this doctoral thesis the documentary prose written in the second half of the 19th century by prominent Serbian cultural workers, artists, statesmen, journalists and politicians is regarded as a valuable material for exploring the links and flows between Serbian cultural and musical histories. I have analysed the dominant types of writings of that time: memoirs, diaries, autobiographies and travelogues, as well as selected biographical essays about the renowned individuals of this period. The sources confirm that, both in the public and private spheres, music was an important segment of all strata of the 19th-century Serbian society in complex geopolitical and cultural-historical contexts. In a diachronic perspective the analysed material reflects the dynamics and evolution of the types of presence of music and musical life in all countries populated by the Serbs in this period: the Habsburg Monarchy, the Principality and Kingdom of Serbia and the Serbian enclaves in other nations. It is confirmed that, among the key features of different cultural models typical for the period of cultural pluralism among the Serbs in the 19th century, the musical currents occupied a special place in the building of the social sphere and the reception of the entire reality..

Supplementary data for the article: Marjanovic Trajkovic, J.; Milanovic, V.; Ferjancic, Z.; Saicic, R. N. On the Asymmetric Induction in Proline-Catalyzed Aldol Reactions: Reagent-Controlled Addition Reactions of 2,2-Dimethyl-1,3-Dioxane-5-One to Acyclic Chiral α-Branched Aldehydes. European Journal of Organic Chemistry 2017, 2017 (41), 6146–6153. https://doi.org/10.1002/ejoc.201701073

Supporting information for: [https://doi.org/10.1002/ejoc.201701073]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2410

Contemporary approaches to intelligence assessment - predictive validity of socio-emotional and practical intelligence tests

Savremena procena sposobnosti oslanja se na primenu testova čije su konstrukcija i interpretacija vođene teorijskim principima i empirijskim nalazima; ujedno, ona podrazumeva obuhvatno ispitivanje većeg broja sposobnosti definisanih Katel-Horn-Kerolovom (CHC) teorijom strukture ljudskog intelekta. CHC model čini teorijsku osnovu većine savremenih baterija inteligencije, ali i okvir spram koga se definišu i empirijski validiraju novi konstrukti iz domena kognitivnih sposobnosti. Istaknuto mesto među novopredloženim sposobnostima imaju emocionalna (EI) i praktična inteligencija (PI). U teorijskom delu rada prikazane su osnovne postavke CHC modela i podrobno analizirana njegova uloga u razvoju savremenih testova inteligencije, te prakse kognitivnog procenjivanja, uopšte; nadalje, izvršen je pregled vodećih teorijskih konceptualizacija, te operacionalizacija EI i PI, kao i nalaza istraživanja usmerenih na njihovu empirijsku validaciju; konačno, data je ocena ispunjenosti uslova za članstvo EI i PI u CHC strukturi sposobnosti. U empirijskom delu rada prikazani su rezultati istraživanja kojim je ispitana uloga EI i PI u predikciji psihičke dobrobiti i profesionalnog zadovoljstva i uspeha, i to kroz istraživački nacrta koji uključuje indikatore akademske inteligencije i bazičnih dimenzija ličnosti. Uzorak ispitivanja činilo je 288 odraslih osoba, zaposlenih u kompaniji mlečne industrije – Imlek AD. Od ukupnog broja, 128 (44.4%) ispitanika je bilo ženskog, a 160 (55.6%) muškog pola; raspon njihovih uzrasta kretao se od 21 do 61 godine (M=40.41). Učesnicima studije zadata je baterija testova za procenu: a) akademske (Ravenove progresivne matrice, Serije brojeva, Verbalne analogije, Test opšte informisanosti), b) emocionalne (MSCEIT) i c) praktične inteligencije (STAT-p); dodatno, ispitanici su popunili inventar ličnosti (NEO-FFI) i skalu psihičke dobrobiti (RSPWB), te izvršili samoprocenu zadovoljstva poslom i uspešnosti u njegovom obavljanju. Podatke o poziciji u poslovnoj hijerarhiji i nivou primanja obezbedio je poslodavac. Nalazi pokazuju da: (1) EI i PI ostvaruju niz statistički značajnih asocijacija s obe grupe kriterijuma – u slučaju psihičke dobrobiti korelacije s EI su niskog do umerenog intenziteta, dok su one utvrđene s PI niže i ne uvek statistički značajne; veze EI s profesionalnim zadovoljstom i uspehom su niske, dok je PI značajno povezana samo s objektivnim indikatorima poslovnog učinka; (2) dimenzije EI i PI objašnjavaju statistički značajan procenat varijanse kriterijuma – nezavisna doprinos predikciji psihičke dobrobiti daju strateške grane EI i verbalni-praktični zadatak; udeo dimenzija EI i PI bitno je niži u predviđanju kriterijuma vezanih za posao; (3) EI uzma značajniji udeo u predviđanju psihičke dobrobiti nego profesionalnog zadovoljstva i uspeha, dok PI ne beleži prednost u predikciji bilo kog kriterijuma; (4) globalni skorovi EI i PI ne daju dodatni doprinos predviđanju kriterijuma kada se kontrolišu varijacije u akademskoj inteligenciji i ličnosti, ali zato njihovi pojedini aspekti uzimaju nezavisan udeo u predikciji; (5) EI i PI sadejstvuju u predviđanju kriterijuma. U zaključku rada se diskutuju osnovni nalazi, izvode implikacije dobijenih rezultata za procenu EI i PI, te navode preporuke koje se tiču njihovog daljeg teorijskog i empirijskog utemeljivanja.Contemporary intellectual assessment rests upon theoretically and empirically driven test construction and interpretation; it also enables comprehensive examination of various Cattell-Horn-Carroll (CHC) theory defined abilities. The CHC model stands as a theoretical basis for the majority of modern intelligence batteries; likewise, it is a framework against which new cognitive ability constructs are defined and empirically validated. Emotional (EI) and practical intelligence (PI) are among the most prominent of these newly proposed abilities. The theoretical section of the paper outlines the CHC theory, and gives a detailed analysis of its role in the development of modern intelligence tests; further, it provides an overview of the leading conceptualizations and operationalizations of EI and PI, and presents research findings concerning their empirical validation; finally, general conclusions are drawn regarding the current status of EI and PI within the CHC structure of abilities. The empirical section of the paper presents features and results of the study investigating the role of EI and PI in predicting psychological well-being and professional satisfaction and success, both with and without the control of academic intelligence and personality. The study sample consisted of 288 adults employed at a large dairy company - Imlek AD. Of these, 128 (44.4%) were females, and 160 (55.6%) were males; age of the subjects ranged between 21 and 61 years (M=40.41). Participants were administered a battery of tests assessing: a) academic (Raven's Progressive Matrices, Number Series, Verbal Analogies, General Knowledge), b) emotional (MSCEIT), and c) practical intelligence (STAT-p); additionally, the subjects completed a personality inventory (NEO-FFI) and the psychological well-being scale (RSPWB), and provided self-assessments of job satisfaction and success. Data on the position in the company and salary were provided by the employer. Research findings show that: (1) EI and PI displayed a number of significant associations with both groups of criteria – correlations of psychological well-being with EI were low-to-moderate, while those identified with PI were lower or non-significant; correlations between professional criteria and EI were low, while PI significantly related only to objective indices of work performance; (2) dimensions of EI and PI explained statistically significant proportions of criteria variance – EI strategic branches and the verbal-practical task gave independent contributions when predicting psychological well-being; EI and PI accounted for considerably lower proportions of professional criteria variance; (3) EI manifested greater predictive potential with respect to psychological well-being then with regard to professional outcomes; PI did not exhibit advantage in predicting any criteria; (4) EI and PI global scores did not show incremental validity, when academic intelligence and personality were held constant, while some of their dimensions surfaced as independent predictors of the criteria; (5) EI and PI contributions in predicting criteria were additive (not overlapping). The concluding section of the paper discusses key research findings, lists their implications for the assessment of EI/PI, and provides recommendations for future research concerned with EI/PI’s theoretical and empirical validation

Benchmark based on application signature to analyze and predict their behavior

Currently, there are benchmark sets that measure the performance of HPC systems under specific computing and communication properties. These benchmarks represent the kernels of applications that measure specific hardware components. If the user’s application is not represented by any benchmark, it is not possible to obtain an equivalent performance metric. In this work, we propose a benchmark based on the signature of an MPI application obtained by the PAS2P method. PAS2P creates the application signature in order to predict the execution time, which we believe will be very adjusted in relation to the execution time of the full application. The signature has two performance qualities: the bounded time to execute it (a benchmark property) and the quality of prediction. Therefore, we propose to extend the signature by giving the benchmark capacities such as the efficiency of the application over the HPC system. The performance metrics will be performed by the benchmark proposed. The experimentation validates our proposal with an average error of prediction close to 7%.Instituto de Investigación en Informátic

The Impact of Firms' Characteristics on Export Barriers' Perception: A Case of Serbian Exporters

This papers analyses impact of firm characteristics, i.e. size, length of exporting experience, capital ownership and type of industry on export barriers´ perception in case of Serbian exporters. This study is aimed at an identifi cation of the barriers to export among examined factors of fi rm´s internal environment, domestic business environment and foreign markets to rank barriers according to their level of impact, to spot differences in evaluation of barriers depending on fi rm´s characteristics, and to examine correlation between firm´s characteristics and barriers to export. Main hypothesis in this research was that barriers to export for Serbian exporters have been similar to those faced by exporters in other countries, and that the level of their infl uence depends on firm´s characteristics. The empirical research has been conducted through a survey, using a questionnaire with 178 exporters taking part in it. Collected data have been analysed by descriptive statistics, differences among groups and correlation tests. The results imply that most export barriers refer to domestic business environment and that there is a correlation among firm´s size, length of export experience and capital ownership with certain factors that may cause problems for exporting business

Thermodynamic and Structural Investigation of the Ag-In-Sb System

The Ag-In-Sb ternary system presents one of the possible lead-free solder candidates. Therefore, the results of thermodynamic study of the alloys in the Ag-In-Sb alloys, obtained using general solution model, are presented in the paper. Obtained data for partial and integral molar thermodynamic quantities in the temperature interval 1000-1200K are given. The characterization of these alloys have been done using DTA, XRD, SEM and optic microscopy, which enabled the construction of the Ag-In-Sb phase diagram in the concentration range up to 60 wt. % Ag

Heavy metals concentration in soils from parks and green areas in Belgrade

The current study included the investigation of several metals and their distribution in urban soils from parks and green areas in the city of Belgrade. The soils were sampled in January and February 2008. The concentrations of Cd, Co, Cu, Pb, Mn and Zn were measured, as well as the pH values and organic matter contents. The obtained results showed that there was a significant level of contamination in some samples, especially with lead, and that it was most probably caused by anthropogenic activities, mostly from traffic. The results were compared with the National legislation and Netherlands standards. Also, the recent results were compared with the data from previous work and it was concluded that there has been a certain increase of the Pb concentration in the past three years. The level of pollution in playground soil was very high and each analyzed sample exceeded the Dutch target value for Cd, Co and Pb

GROWTH AND DEVELOPMENT DYNAMICS OF TERMINAL SPROUT IN PROVENANCE TRIALS OF SILVER FIR (ABIES ALBA MILL.) OF PLANTS IN CROATIA

Jedna od najvrijednijih vrsta četinjača u Hrvatskoj je obična jela (Abies alba Mill.) koja zajedno s bukvom i smrekom raste na približno 150 000 ha šuma Like i Gorskoga Kotara na kojima se preborno gospodari. Prva istraživanja uspijevanja različitih provenijencija obične jele u Hrvatskoj započela su sakupljanjem sjemena u jesen 1994. godine. Sakupljeni su uzorci sjemena iz 18 priznatih i izabranih sjemenskih sastojina u Hrvatskoj i u dvije slovenske sjemenske sastojine, te je osnovan rani test provenijencija u rasadniku šumarskog instituta, Jastrebarsko. U svrhu daljnjih istraživanja na području Uprave šuma Podružnica Delnice, Šumarija Fužine, lokalitet Brloško, tijekom 2000. godine i u rasadniku Instituta 2001. godine osnovani su poljski pokusi. U radu su prikazani rezultati istraživanja rasta terminalnog izbojka biljaka starosti osam godina. Prosječni prirast biljaka u pokusu "A-polje" u 2002. iznosio je 45,1 mm, a na pokusu provenijencija "Brloško" 156,8 mm. Analizom varijance utvrđeno je postojanje statistički značajnih razlika između provenijencija u dinamici njihova rasta.One of the most valuable conifer tree species in Croatia is Silver fir (Abies alba Mill.). Growing mostly in Lika and Gorski kotar region in pure or mixed with beech and spruce stands it covers area of approximately 150 000 ha, managed using tree selection system. First research on growth of different provenances of silver fir in Croatia begun with seed collection in the autumn of 1994. Collected were seeds from 18 Recognized Seed Stands in Croatia and two from Slovenia and an early provenance test was established in the nursery of Forest Research Institute. Further research involved establishment of field trial in the year 2000 at the locality Brloško on the territory of Forest Management Unit Delnice, Forestry Office Fužine, and in the year 2001 on the Forest Research Institute in Jastrebarsko. In this paper we present results of the research of growth of terminal sprout on fir seedlings aged eight years. Average height increment in the year 2002 for the plants in "A-Field" provenance trial was 45.1 mm, while for the provenance trial "Brloško" average height increment amounted to 156.8 mm. Analysis of variance showed that statistically significant difference exists in growth dynamics of different provenances