A use of Cournot's competition model in oligopolistic markets in the terms of limited capacities

Cilj ovog rada je da teorijski utemelji primenu Kurnoovog modela kao skraćene forme dvostepene konkurencije na oligopolskim tržištima u uslovima ograničenih kapaciteta. Razvijen je model koji predstavlja prečicu za analizu potencijalnih efekata na blagostanje horizontalnih spajanja preduzeća. Model mogu upotrebiti komisije za zaštitu konkurencije kao simulacioni model pri kontroli horizontalnih spajanja preduzeća. Pokazano je da se ishod modela dvostepene konkurencije, gde se preduzeća obavezuju na određene nivoe kapaciteta, pre konkurencije cenama, poklapa sa ishodom Kurnoovog modela količinske konkurencije. Šta više, ispostavlja se da ovaj rezultat važi kako za tržišta homogenih proizvoda tako i za tržišta diferenciranih proizvoda. To protivreči gotovo standardnom stavu da je količina strateška varijabla isključivo na tržištima homogenih proizvoda. Robusnost ovog rezultata proverava se kako za simetrični oligopol, što predstavlja standardno polazište svih modela iz ove klase, tako i za okolnost asimetričnog oligopola. Asimetrija se uvodi kroz internalizaciju konkurencije izazvanu spajanjem dva simetrična preduzeća na tržištu diferenciranih proizvoda. Komisijama za zaštitu konkurencije je predložen algoritam za primenu modela simulacija. U skladu sa definisanim koracima, sprovedene su simulacije spajanja na realnom primeru, primenom Kurnoovog modela konkurencije u uslovima ograničenih kapaciteta. Na osnovu rezultata simulacija, komisijama su date praktične preporuke za sprovođenje kontrole koncentracija.The objective of the thesis is to examine the Cournot model as a reduced form of the two-stage competition in oligopolistic markets with limited capacities. A short-cut model for analysing welfare effects of potential horizontal mergers is developed. The model can be used by Anti-trust commissions as a simulation model in the process of horizontal merger assessment. It is shown that the outcome of the two-stage competition, where firms had been conditioned by their level of capacities even before the price competition has started, coincide with the outcome of the Cournot quantity competition model. Moreover, it turns out that this result is valid for both the homogeneous product markets and the markets of differentiated products. This contradicts an almost universal belief that the quantity is a strategic variable exclusively within the homogeneous product markets. The robustness of this result is examined both for symmetric oligopoly, which is a starting point for all models in the class, and for the asymmetric oligopoly. The asymmetry is introduced through the internalisation of competition due to a merger of two symmetric firms in the differentiated products market. The implementation algorithm of the simulation model is suggested to the Anti-trust commissions. In accordance with defined steps, merger simulation can be carried out in the real world by using the Cournot model of competition with limited firm capacities. Based on the simulation results, practical recommendations for the merger control policies are offered to the commissions

Analysis of seasonal variations in the nitrogen dioxide levels in the city of Bor in the periods 2010-2013 and 2019-2023

In addition to traffic, the main source of nitrogen dioxide is also industrial plants where combustion takes place at high temperatures, such as heating plants and smelters. Nitrogen oxides from traffic are the dominant component of air pollution in large cities and represent an important source of exposure and health risk for people, especially those who move along busy roads. In Bor, real-time nitrogen dioxide concentrations have been measured since 2010 at the measuring point "Institute IRM Bor" near Mining and Metallurgy Institute Bor. This paper presents an analysis of the results of measuring nitrogen dioxide concentrations in Bor in the periods 2010-2013 and 2019-2023. Based on the analysis of nitrogen dioxide measurement results, it was established that in both periods there are seasonal changes (heating/non-heating season) in nitrogen dioxide concentrations. Nitrogen dioxide concentrations were on average 17% higher in the heating season than in the non-heating season. Also, in the period 2019-2023 the average concentration of nitrogen dioxide was 28.6 µg/m3 , which is about 18% more compared to the period 2010-2013 in which the average concentration of nitrogen dioxide was 24.3 µg/m3 . In the observed periods, there was no exceedance of the limit value for the average annual concentration of nitrogen dioxide of 40 µg/m3 . However, several days were recorded with an average daily concentration of nitrogen dioxide above the daily limit value of 85 µg/m3

Istraživanje pojave afričke kuge svinja na velikoj komercijalnoj farmi svinja u Srbiji

The fi rst confi rmed case of African Swine Fever (ASF) in Serbia occurred in 2019. Since then, numerous outbreaks in domestic pigs and wild boars have been reported. Until April 2021, all the detected ASF cases were in backyard pigs. Beside backyard and smallholders farming systems as a dominant pig production system in Serbia, large commercial pig farms can also be found, located mostly in villages. In the beginning of April 2021, a large commercial farrow-to-fi nish pig farm in Serbia with almost 19,000 animals was affected with the ASF virus. The pig farm analysed in this paper is located in an area where ASF was confi rmed earlier in both backyard and wild boars. In this study, we describe the overall epidemiological course of the ASF outbreak. Epidemiological investigation using a hypothesis-based approach was conducted in order to reconstruct the disease course until the offi cial notifi cation. All the available data from the farm were analysed with the aim to determine the high-risk period (HRP). Some of the key points to consider when it comes to the sources of infection and entry route of ASF are the following: contamination of the area in the immediate vicinity of the farm, risky human activities, irregularities and some omissions in the external farm biosecurity and immediate proximity of the city waste-yard where the communal waste is disposed of. It was concluded that when commercial pig farms are surrounded by villages with a large number of backyards, hence the anthropogenic factor is the key risk factor for ASF spreadingPrvi slučaj afričke kuge svinja (AKS) u Srbiji je dijagnostikovan 2019. godine. Od tada, beleži se pojava bolesti u populaciji domać ih i divljih svinja. Sve do aprila 2021. godine žarišta AKS su bila lokalizovana u populaciji domaćih svinja u seoskim dvorištima. Pored seoskih gazdinstava i porodičnih farmi kao dominantnog načina proizvodnje, u Srbiji se nalaze i velike komercijalne farme svinja, uglavnom oko seoskih naselja. Početkom aprila 2021. godine, u komercijalnoj farma svinja, proizvodnog kapaciteta oko 19000 jedinki, potvrdjena je infekcija virusom AKS. U radu je sa epizootiološkog aspekta, hronološki opisan tok infekcije AKS. Epizootiološko istraživanje je zasnovano na hipotezama u cilju utvrdjivanja potencijalnih puteva unošenja AKS. Analizirani su dostupni farmski podaci kako bi se utvrdio vremenski period visokog rizika (HRP). Farma svinja se nalazi u području gde je u prethodnom periodu potvrđena AKS u seoskim gazdinstvima, kao i u populaciji divljih svinja. Kontaminacija ambijenta u neposrednoj blizini farme, visoko rizične aktivnosti humane populacije u okruženju (brojna seoska gazdinstva), postojanje pojedinih aktivnosti visokog rizika u realizaciji eksterne biosigurnosti i neposredna blizina gradske deponije gde se odlaže komunalni otpad, su svakako ključni momenti kada se razmatraju izvori infekcije i put unošenja AKS. Zaključeno je da u uslovima kada su komercijalne farme okružene selima, u kojima su dominira uzgoj domaćih svinja u seoskim dvorištima, ljudske aktivnosti predstavljaju ključni faktor rizika za širenje AKS

Fostering farmer engagement: ECOBREED participatory trials on organic soybean in Serbia

Farmer Participatory trials (FPTs) promote cooperation and knowledge exchange among farmers and researchers in specific agro-climatic conditions. Farmers who actively participate in field experiments are empowered to share their knowledge and preferences. To test and spread innovations in organic production, farmers actively participate in the decision-making process regarding plant variety selection. Farmer participatory trials for organic soybean production were established in five European countries as part of the ECOBREED project. The goal of these trials was to support farmers in selecting new varieties for their respective pedo-climatic zones and locations. This involves farmers directly in the process of developing new soybean varieties, particularly when it comes to working with breeders to observe cross composite populations (CCPs). FPTs for organic soybean were set up in Serbia (2021-2022). Up to 10 soybean varieties were tested on up to 5 locations for two years period. Trial results have big variations within specific locations and production years. Organic farmers continued with testing some subset of soybean varieties in 2023. FPTs are pathway for increasing the uptake of new and improved soybean varieties for low-input and organic production

Analysis of floating-head heat exchanger bolts failure

As-received floating-head heat exchanger bolts were broken (BB) and deposite-coated. The aim was to estimate a cause of their failure. The new bolts of the same material were used as a reference material (reference bolt – RB). After visual and radiographic examination, their chemical composition, structure and room-temperature mechanical properties were determined and compared. Comparison was made with the values set by standard, as well. Afterwards, fractography was performed on fractured surfaces of tensile specimens and originally (during exploitation) BBs to try to get an impression about bolts failure mechanism. Qualitative analysis of deposite was employed in order to confirm was there any possible influence of surroundings during their failure in terms of corrosion-assisted cracking. Chemical composition of RB and BB materials was analyzed by use of spectrophotometry and structure properties with light optical microscope (LOM). Fractured surfaces of tensile specimens and of BBs, as well as deposite chemistry, were analyzed by use of Scanning Electron Microscopy with Energy Dispersive System (SEM-EDS). BBs had an approximately three times higher sulphur content and lesser manganese content, lower ductility and higher strength values comparing to those of the RBs. Generally, fracture surfaces of both, RB and BB tensile specimens have a similar rosette-like macro-appearance. The only difference is that the radial marks in the case of the RBs are rougher. The surface has a more fibrous area and shear lip presence. Fracture mode can be characterized as dimple rupture and micromechanism as microvoid coalescence. In the case of BB tensile specimens, the mixed presence of dimples and cleavage facets was noticed. The macrofractography of originally broken surfaces shows a rough and complex topography of fracture surfaces indicating on a possibility that bolts failure has been a result of complex loading conditions. Presence of sulphur- and chlorine-containing particles on the fracture surfaces of BBs and in deposite reveals a possibility that failure was environmentally-assisted

Air quality in the city of Bor in 2023

The air quality in the city of Bor in 2023 is analysed in this paper. In the period from May 1, 2022 until April 1, 2023 the copper smelter in Bor was not working due to reconstruction and capacity increase. The analyses show that in 2023, no exceeding of the daily limit value for SO2 , PM10, and soot concentrations was detected at any measuring point. During the reconstruction of the copper smelter, correlation coefficients (Pearson) at measurement point "Jugopetrol" between PM10 and the chemical elements Cd and As were moderate (0.6>r>0.4), while in the period before and after the reconstruction of the smelter, they were strong (0.8>r>0.6), and very strong (r>0.8). The results presented in the paper indicate that despite the reconstruction of the copper smelter, the problem of emission of high concentrations of carcinogenic elements in PM10 from the copper smelter is still present. It is necessary to urgently implement additional measures to reduce these emissions to the values provided by law

Measurement of the air quality in the agglomeration of Bor in 2022 during the copper smelter reconstruction in Bor

This paper presents the results of the air quality measurements in the agglomeration of Bor in the period June-December 2022, in which the Copper Smelter in Bor was not working due to the works on reconstruction and increasing the capacity for copper concentrate processing. Based on an analysis of the existing measuring points and concentrations of pollutants, measured in the local and national air quality monitoring network in the territory of the Bor agglomeration, as well as the possible impact of the new mining and metallurgical facilities in the company Serbia ZiJin Copper Bor, the additional locations, where the measurements were performed, were selected. The air quality measurement results show that there was no exceedance of the hourly and daily limit values for gaseous pollutants, nor were there an exceedance of the limit value for the mean daily concentration of lead in the suspended particles of the PM10 fraction, as well as the target values for the concentrations of cadmium and nickel in PM10. The arsenic concentration in PM10 at the measuring point of PU Bor was above the target annual value for 3 days. The maximum measured mean daily value of arsenic concentration in PM10 at this measuring point was 11.3 ng/m3 . Based on a complete insight into the results of air quality measurements in the Bor agglomeration in 2022, it can be concluded that the dominant share of concentration of SO2 , CO, as well as the concentration of arsenic, cadmium, and lead in PM10, originates from the gaseous pollutant emissions from the Copper Smelter Bor in the period when it operates. It was established that at the measuring point MMI Bor, the nitrogen oxide emissions from traffic mostly affect the level of nitrogen oxides in the air. Also, the measurement results indicate that the operation of the Smelter in 2022 did not significantly contribute to the concentration increase of suspended PM10 particles in the agglomeration of Bor, and that during the period of operation of the Copper Smelter in 2022, no copper concentrates with increased nickel content were processed

OPTIMISING INVESTMENT IN THE ENERGY SECTOR IN DEVELOPING COUNTRIES IN SOUTH EAST EUROPE

In this paper we are researching the optimality of developing counties for investing in their energy sector as a way of diversifying portfolio by applying the multicriteria decision making model There are multiple quantitative and qualitative criteria that can be considered when finding the adequate market for investment, other than its natural potential, such as the level that its energy sector is developed, legal framework that surrounds this sector, market openness of the observed economy, ease of investment and market liquidity. The four sources of the energy sector that are considered are oil, gas, coal and renewable energy sources. Even though the renewable energy sources aren’t sufficiently exploited, the countries that have high potential could provide significant financial profits by exploiting them

Metal and metalloid bioaccumulation in three centipedes (Chilopoda)

Three centipede species (Clinopodes flavidus, Cryptops anomalans and Eupolybothrus transsylvanicus) were used as bioindicators of trace metal and metalloid pollution in Belgrade, Serbia. The concentrations of 13 elements (the metals Mn, Co, Ni, Cu, Zn, Rb, Sr, Cd, Tl, Pb and U and metalloids As, Se) in whole animals and soil were measured by inductively coupled plasma mass spectrometry (ICP-MS). Differences in the concentrations of some elements in the analyzed species were observed, both in response to the sites and between species. In most cases, the trace element concentrations were higher in centipedes from a polluted site (an industrial area near a busy street with heavy traffic) but C. anomalans and E. transsylvanicus had higher Mn concentrations at an unpolluted site (a deciduous woodland on Mt. Avala). C. flavidus was a good bioindicator for detecting differences between Zn, Se and Cd. C. flavidus and C. anomalans were more efficient in accumulating Zn than E. transsylvanicus. It appears that C. anomalans poorly accumulated Cd, unlike C. flavidus and E. transsylvanicus, which accumulated Cd according to the high bioaccumulation factor (BAF) values. We conclude that the centipedes C. flavidus, C. anomalans and E. transsylvanicus can be used as suitable bioindicators of trace element exposure. Their ability to accumulate trace elements was different and depends on their physiology and lifestyle as well as the route of exposure.Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/5673

Zoonotic helminthosis of domestic and wild carnivores in the epizootiologic territory of Serbia

In the last decade, as the result of climate changes, there have been considerable changes in the parasitofauna of domestic and wild carnivores. Th e prevalence of the existing parasitic species has varied signifi cantly, showing an increasing tendency, and some parasitic species not present before in this epizootiologic territory have been diagnosed as well. It is thought that the reason for such an epizootiological situation is increased presence of owners with their pet animals in the regions endemic for particular zoonotic helminthoses during summer holidays and touristic visits. Th is tendency has become especially conspicuous in the last several years characterized by warm winters and very hot summers due to global warming eff ects, with abundant atmospheric precipitation. Oral vaccination of foxes against rabies, regulated in Serbia by appropriate laws since 2010, has led to an increased number of foxes and rise of prevalence of the parasitic diseases for which foxes represent the infection source/reservoir. Continued urbanization of Serbian cities, with the extension of urban belts into the suburbia and recreational (“weekend”) settlements, lead to a closer contact of street dogs and owned dogs with foxes, which results in a signifi cant change in the parasitic fauna of dogs. It is an additional factor, which in the chain fox - street dog - owned dog - human increases the risk and tendency for the occurrence of human infections with zoonotic endoparasites of wild and domestic carnivores. In order to reliably predict the degree of spread of particular zoonotic helminthoses in particular regions in Serbia, for which wild carnivores represent the infection source, it is necessary to institute continued monitoring of the parasitic fauna in this type of wild animals