Between cv builder" and "genuine" activist: the many faces of youth civic engagementin Serbia

The aim of this paper is to explorethe characteristics and relative importance of civic engagement for young members of civil society organisations in Serbia. This article is exploratory in character and is based on qualitative methodology. Youth engagement is observed through the theoretical lens of the lifecourse approach. The questions addressedbythe paper are as follows: How do young people perceive their civic engagement? What motivates their participation? How does this engagement relate to other aspects of their lifecourse? The method used here is narrative analysis of 20 semi-structured interviews conducted with young volunteers and members of civil society organisations in Serbia selected through theoretical sampling. The key finding is that there is arange of motivations and accompanying strategies - from the purely idealistic to the highly instrumental. The majority of our respondents displayed a mixed type of motivation, successfully combiningactivities aimed at protectingthe "social good" with thosethat contribute to the achievement of personal goals. Motivation, however, tends to vary between the different types of organisations, professional and grassroots. Engagement in professional organisations is more frequently instrumental and, in contrast, grassroots organisations typically attract "genuine", value-driven activists

On the space restitution of the laguerre’s points associated to the perspective elliptical involuted ranges

Ovaj rad izlaže dokaz, zasnovan na metodi prostorne restitucije, da geometrijsko mesto Lagerovih tačaka perspektivnih eliptičnih involutornih nizova predstavlja dva kruga. Osim što daje doprinos teoriji Projektivne geometrije, izložena teorema omogućava veću efikasnost konstruktivnih postupaka i kompjuterskih algoritama osne rotacije objekata u centralnoj projekciji.This paper discloses the proof, based on the method of the space restitution that geometrical loci of Laguerre's points of perspective elliptical involuted ranges represent two circles. The exposed theorem is a contribution to the theory of Projective geometry; moreover it makes the constructive methods and computational algorithms of an object axial rotations in central projection more effective

Low-nutrient R2A medium in monitoring microbiological quality of drinking water

The possibility of using low-nutrient R2A medium for determining the total count of aerobic mesophilic bacteria was investigated. Sampling of water from particular points of water treatment and distribution at Kruševac drinking water treatment plant was conducted. The samples were inoculated simultaneously on Plate Count Agar (PCA) and R2A media, and incubated at 37 °C and at room temperature. The bacterial count was determined after 48, 72, 120 and 168 h. The statistical analysis of the results showed significantly higher bacterial count on R2A medium compared to PCA. Moreover, a significantly higher bacterial count developed at room temperature compared to the temperature of 37 C. R2A medium recorded 3.6% of unsafe samples in the distribution system after the 7-day incubation at room temperature. On the basis of the ob¬tained results, an optimum method for determining the total count of aerobic mesophilic bacteria for all investigated waters has been defined. The process of incubation is predictable and it can be described by a mathematical model in the form of a polynomial of the second or the third power

2D Analytical Model for Evaluation of the Forces in the Three-point Hitch Mechanism

Large investments, research efforts and time have been allocated till nowadays for innovation of agricultural tractors and machinery, with the primary aim to increase their productivity, reliability, durability, as well as the environmentally friendly, safe and easy usage. Following this general trend, present work is focused on theoretical analysis of the forces acting on the links of the three-point hitch mechanism. The simulation algorithm and computer code have been developed for calculation of draft forces by two methods (following ASAE D497.4 standard and Goryachkin approach), depending on the three point linkage geometry and mouldboard technical characteristics, and calculation of forces acting on lower and upper links of three-point hitch mechanism. Calculated forces values, based on ASAE draft, exposes smaller differences compared to experimental values, while for the Goryachkin method improvement is possible by entering experimental values for soil resistance coefficient k and coefficient of dynamic resistance s, as we did in this study performing measurements on the aggregate comprehending tractor IMT 539 (IMT Belgrade, Serbia) and two furrow moldboard plough PTO 2.25 (OLT, Osijek, Croatia)

Raspodela koncentracija prašine u vazduhu objekta za krave pri različitim režimima ventilacije

Information on the concentration of dust particles is an important microclimate parameter that characterizes the local environmental quality of each livestock building. Increased concentration of dust particles primarily affects the indoor air quality and, consequently, the animal and workers health. Among many others, ventilation rate is a vital parameter that controls the spatial distribution of airborne dust particles in livestock buildings. This was the main motive for authors of this paper to research the influence of rotation rate of under-roof axial fans (i.e. the air flow rate) on airborne dust particles distribution crossover the barn specified for tied cows breeding. During a series of performed experiments, six different air flow rates have been maintained in the range between 0 m3·h-1 and 48000 m3·h-1. Flow rate has been controlled by special electronic control unit, which provided six different rotation rates of two under-roof fans, including the neutral regime (natural ventilation only). Measurements have been performed at four typical height levels (0,5 m; 1,0 m; 1,5 m and 2,0 m), cross-over the three lateral and four longitudinal characteristic building sections. Consequently, 48 measuring points were appropriately selected, in order to cover the indoor space in adequate way. Comparative analysis of air flow velocities and dust concentrations showed that this fan setup may give satisfactory results under adequate operational regime. Certain working regimes were recommended for use, and the third rotation rate step, generating the airflow of 37300 m3·h-1 or indoor air exchange level of approximately 25 h-1, has been found as the most suitable.Koncentracija čestica prašine je je važan mikroklimatski parametar koji karakteriše kvalitet ambijenta svakog stočarskog objekta. Povećana koncentracija prašine primarno utiče na kvalitet stajskog vazduha, a time i na zdravstveno stanje životinja i ljudi. Pored ostalih, intenzitet ventilacije je značajan parametar u kontroli prostorne raspodele koncentracija prašine u stočarskim objektima. Ovo je bio motiv autora da sprovedu istraživanje uticaja režima rada krovnih aksijalnih ventilatora (tj. intenziteta strujanja vazduha) na raspodelu koncentracija prašine u staji za vezao držanje krava. Tokom izvođenja ogleda ispitivan je uticaj šest različitih intenziteta strujanja vazduha u opsegu od 0 m3·h-1 do 48000 m3·h-1. Režimom rada ventilatora je upravljao elektronski kontrolni uređaj, kojim je određivano šest različitih brojeva obrtaja za dva krovna ventilatora, uključujući i neutralni režim (samo prirodna ventilacija). Koncentracija je merena na četiri visine (0,5 m; 1,0 m; 1,5 m i 2,0 m iznad poda), po tri poprečna i četiri podužna preseka objekta. Tako je dobijeno 48 pravilno raspoređenih mernih tačaka, koje su ravnomerno pokrivale unutrašnji prostor staje. Komparativnom analizom brzina strujanja vazduha i koncentracija prašine zaključeno je da ispitivani položaj ventilatora može da da zadovoljavajuće rezultate pri odgovarajućem režimu rada. Preporučeni su najpovoljniji radni režimi za upotrebu. Kao najpovoljniji izdvojen je treći ispitivani režim sa protokom vazduha od 37300 m3·h-1, odnosno 25 h-1 ostvarenih izmena vazduha

2D Analytical Model for Evaluation of the Forces in the Three-point Hitch Mechanism

ABSTRACT Large investments, research efforts and time have been allocated till nowadays for innovation of agricultural tractors and machinery, with the primary aim to increase their productivity, reliability, durability, as well as the environmentally friendly, safe and easy usage. Following this general trend, present work is focused on theoretical analysis of the forces acting on the links of the three-point hitch mechanism. The simulation algorithm and computer code have been developed for calculation of draft forces by two methods (following ASAE D497.4 standard and Goryachkin approach), depending on the three point linkage geometry and mouldboard technical characteristics, and calculation of forces acting on lower and upper links of three-point hitch mechanism. Calculated forces values, based on ASAE draft, exposes smaller differences compared to experimental values, while for the Goryachkin method improvement is possible by entering experimental values for soil resistance coefficient k and coefficient of dynamic resistance ε, as we did in this study performing measurements on the aggregate comprehending tractor IMT 539 (IMT Belgrade, Serbia) and two furrow moldboard plough PTO 2.25 (OLT, Osijek, Croatia)

The design of a full flow dilution tunnel with a critical flow Venturi for the measurement of diesel engine particulate emission

Na osnovu međunarodnih standarda, potreba korisnika i zahteva proizvođača realizovan je tunel za razređenje izduvnih gasova. Pri konstruisanju tunela uzet je u obzir niz ograničenja definisanih u standardima o kontroli emisije i izboru venturija. Potrebni podaci pri definisanju osnovnog koncepta tunela dobijeni su iz brojnih ispitivanja emisije obavljenih u Institutu IMR. U radu je takođe prikazan i kraći postupak proračuna dimenzija venturija kritičnog strujanja. Posebna pažnja je posvećena merenju emisije čestica koristeći metodu razređenja izduvnog gasa, što ne dozvoljava korišćenje jednostavnih termodinamičkih i strujnih parametara. Usvojen je metod određivanja emisije čestica za dva krajnja slučaja koja se mogu pojaviti tokom ispitivanja. Koristeći rezulate proračuna konstruisan je i izrađen tunel za razblaženje punog protoka sa venturijem kritičnog strujanja koji je zatim ispitan u Institutu IMR.An appropriate type of dilution tunnel is chosen, based on the international standards, user's needs and the manufacturer's requirements. During the design process, a number of restrictions specified in the standards for emission and Venturis were taken into account. The data required to address basic concepts were obtained from numerous emission tests performed at the IMR Institute. A short algorithm of calculation of the critical flow Venturi (CFV) is also presented. Specific attention is paid to the problems of the measurement of particulate emissions using the dilution method, which does not allow us to use the unique thermodynamic and flow parameters. A method of evaluation of particulate emissions for two extreme cases which were expected during the tests was adopted. Using the results of calculations, a full flow dilution tunnel with CFV was manufactured and tested at the IMR Institute

The assessment of genetic potential in performance tested gilts by means of selection indexes method

The objective of this research paper was to make an assessment of breeding value of performance tested gilts of Swedish Landrace and F-1 crossbreds of Swedish Landrace and Great Yorkshire by the method of selection index. The traits on whose basis the breeding value was estimated were: daily liveweight gain, average backfat thickness measured at two sites and carcass meat percentage. These traits were corrected for body mass of 100kg by the method of base indexes and the following average values were determined: corrected daily liveweight gain (KZDP) 408.93g/day, corrected average backfat thickness measured at two sites (KSL) 9.77mm and corrected carcass meat percentage (KPM) 61.08%. Studying the effect of genotype, year and birth season of gilts a statistically significant variation (P>0.05) of these traits provoked by the mentioned factors was not determined while the gilts sire statistically highly significantly (P lt 0.001) influenced all studied traits. Heritability coefficients were: h(2)= 0.255 for KZDP, h(2)= 0.356 for KSL and h(2)= 0.349 for KPM. The four selection index equations were constructed among which as the most optimal was chosen the one which includes all three traits (KZDP, KSL and KPM) and whose coefficient of the correlation of selection index and aggregate genotype was r(IAG) = 0.594

Joint effects of vitamin D and nanobiomaterial in the jaw bone regeneration

Systems for targeted delivery of drugs with high affinity for specific organs, tissues, and cells were introduced at the beginning of the twentieth century. Recently, this concept is attracting much attention. These systems have shown most effective in reducing adverse effects of drugs. In recent years, scientists have created a system of nanoparticles for delivery of vitamin D. Special attention is paid to the role of vitamin D in the division and differentiation of osteoblasts and thus, in its role in osteogenesis. In this regard it was interesting to observe the local effects of the active form of vitamin D3 in osteogenesis, as a part of the system for local delivery. These effects were observed on an experimental model. Three types of nanobiomaterial were implanted in the artificially made defects in rats’ mandibular bone. Six weeks after implantation of hydroxyapatite, hydroxyapatite-coated vitamin D3 and hydroxyapatite nanoparticles coated with vitamin D3 mixed with the polymer, the animals were sacrificed, and the samples of mandibular alveolar bone were taken. The samples were adequately prepared and subjected to histopathological analysis. The best results in regeneration of osteoporotic jaw bone were obtained in the experimental group of animals where the implant was hydroxyapatite-coated vitamin D3 mixed with the polymer. The results show that nanobiomaterials with local delivery of active form of vitamin D3, used in this study, may be materials of the future in the area of weakened jaw bone tissue regeneration