Logike sa metričkim operatorima

The aim of this paper is to combine distance functions and Boolean proposi­ tions by developing a formalism suitable for speaking about distances between Boolean formulas. We introduce and investigate a formal language that is an extension of classical propositional language obtained by adding new binary (modal -like) operators of t he form D≤ s and D≥ s , seQt, Our language all­ ows making formulas such as D≤ s(a , (3 ) with the intended meaning 'distance between formulas a and (3 is less than or equal to s'. The semantics of the proposed language consists of possible worlds with a distanc e function defined between sets of worlds. Our main concern is a complete axiomatization that is sound and strongly complete with respect to the given semantics

Electron-phonon coupling in crystalline organic semiconductors: Microscopic evidence for nonpolaronic charge carriers

We consider electron(hole)-phonon coupling in crystalline organic semiconductors, using naphthalene for our case study. Employing a first-principles approach, we compute the changes in the self-consistent Kohn-Sham potential corresponding to different phonon modes and go on to obtain the carrier-phonon coupling matrix elements (vertex functions). We then evaluate perturbatively the quasiparticle spectral residues for electrons at the bottom of the lowest-unoccupied- (LUMO) and holes at the top of the highest-occupied (HOMO) band, respectively obtaining $Z_e\approx 0.74$ and $Z_h\approx 0.78$. Along with the widely accepted notion that the carrier-phonon coupling strengths in polyacenes decrease with increasing molecular size, our results provide a strong microscopic evidence for the previously conjectured nonpolaronic nature of band-like carriers in these systems.Comment: final, published versio

Digital Marketing Strategy and Application of Social Media in Crisis PR on Railways

This paper analyzes how the Infrastructure of Serbian Railways, using digital communication channels and social media, can influence public information, views and forms public opinion about railways. In the research, the authors specifically analyze the activities and measures released by the crisis PR in social media of the above mentioned company aiming to inform about railway accidents, and form public opinion. Also, the authors study and define the use of social media by crisis PR on railways as part of the digital marketing strategy in this railway company. The research aims to determine whether railways can reduce the negative consequences of the railway accidents in the public through social media. The authors conclude that the Infrastructure of Serbian Railways can reduce such negative consequences with quick and accurate information in social media and avoid inaccurate and sensational announcements by informing citizens promptly. Considering this, the paper also defines future digital activities by crisis PR in the event of railway accidents

Acute Toxicity Assessment of Orally Administered Microplastic Particles in Adult Male Wistar Rats

While the effects of chronic exposure to microplastic particles (MPs) are extensively studied, the outcomes of a single treatment have received relatively less attention. To investigate MPs’ potential acute toxicity, including their impact on general health status (victual consumption, sensorimotor deficits, and clinical toxicity signs) and serum biochemical parameters (markers of organ/tissue function and oxidative stress indicators), we administered thoroughly characterized MPs (1.4, 35, or 125 mg/kg), generated from polyethylene terephthalate (PET) bottles, to adult male Wistar rats via oral gavage. The MPs’ short-term effects were assessed with well-established tests and methods. The results point to the absence of sensorimotor deficits and clinical toxicity signs, while levels of markers of liver, heart, and kidney function were altered in all MP groups. Decreased victual consumption and increased levels of oxidative stress indicators were evident following treatment with the two higher MP doses. Presented data indicate that examined MPs are able to initiate the development of local changes in tissues and organs within a short time frame, potentially leading to their damage and dysfunction. This study may increase the awareness of the detrimental effects of plastic contamination, as even a single exposure to MPs may provoke adverse health outcomes

Osteogenic differentiation of dental pulp stem cells influenced by synthesized calcium phosphate-based nanomaterial in vitro

Dental pulp stem cells (DPSCs) are mesenchymal stem cells that may have a versatile and abundant application in regenerative medicine and dentistry due to their availability, possibility of isolation from different types of teeth and potential to differentiate into several cell types. In recent years, there is an emerging trend of the use of nanomaterials in medicine and dentistry that, by virtue of their unique properties, have become very attractive as a tool for the treatment of bone tissue defects. The aim of our study was to examine the potential of synthesized nanomaterial, intended for bone tissue engineering and regenerative applications, biphasic calcium phosphate coated with poly-D,L-lactide-co-glycolide (CP/PLGA), to influence the osteogenic differentiation of DPSCs. Cells were obtained from the mature healthy teeth by outgrowth of the cells from undigested pulp pieces during culturing, in standard cell culture conditions. Cells were subjected to osteogenic differentiation for seven and 14 days by culturing the cells with two concentrations of CP/PLGA nanoparticles in the presence or absence of osteogenic supplements in the media. Osteogenic differentiation was assessed by phase contrast microscopy as well as by Von Kossa and Alizarin Red S staining of formed inorganic deposits. The results showed that CP/PLGA influenced osteogenesis in concentration-dependent manner and differently in osteogenic and standard cell culture media. The use of calcium phosphate-based nanomaterials in combination with DPSCs, under certain conditions, could be a promising approach in regenerative medicine and dentistry

Promene u strukturi ćelijskog zida lucerke tokom vegetacije

The investigation was done on 141 samples of one alfalfa cultivar, collected from the same location during the first three growth cycles: spring growth, the first and the second regrowth. Within each growth cycle, sampling was done during the whole growing period, commencing when plant height was below 150 mm and continuing until plants were bearing ripe seeds. On all collected samples the following cell wall characteristics were determined: neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), neutral detergent insoluble crude protein (NDICP), acid detergent insoluble crude protein (ADICP). Cellulose and hemicellulose were detected on the base of the mentioned chemical parameters. Significantly lower (p lt 0.01) content of aNDF, ADF, ADL, ADICP and cellulose is found in the second regrowth, while there were no significant differences between the other two growth cycles. Except in NDICP and ADICP, the increase in all accompanying components of the cell wall was observed, and expressed in average daily changes. There was no consistent trend in NDICP and ADICP. During the spring growth from late bud to full-bloom stage the 'plateau' was observed. The plateau was represented as almost constant content of aNDF, ADF, ADL and cellulose. The correlations between all components of the cell wall were shown. The equation aNDF = 36.713 + 1.181 × ADF is recommended for conversion of ADF into aNDF in alfalfa.Istraživanje je sprovedeno na 141 uzorku iste sorte lucerke, sakupljene na istoj lokaciji tokom prva tri ciklusa vegetacije: prolećni ciklus, drugi ciklus i treći ciklus. Tokom svakog ciklusa, uzorkovanjem je obuhvaćen ceo ciklus vegetacije, od momenta kada su biljke imale visinu manju od 150 mm sve do momenta kada su biljke imale zrelo seme. U svim sakupljenim uzorcima određeni su sledeći parametri ćelijskog zida: vlakna nerastvorljiva u neutralnom deterdžentu (aNDF), vlakna nerastvorljiva u kiselom deterdžentu (ADF), lignin (ADL), protein nerastvorljiv u neutralnom deterdžentu (NDICP), protein nerastvorljiv u kiselom deterdžentu (ADICP). Celuloza i hemiceluloza su određene na osnovu navedenih hemijskih parametara. Utvrđena je značajno manja (p lt 0.01) količina aNDF, ADF, ADL, ADICP i celuloze u trećem ciklusu vegetacije, dok između ostala dva ciklusa nisu utvrđene veće razlike. Izuzev kod NDICP i ADICP, utvrđen je porast svih praćenih komponenata ćelijskog zida i izražen u prosečnim dnevnim promenama. Kod NDICP i ADICP je zabeleženo odsustvo trenda. Tokom prolećnog ciklusa od faze punog pupoljenja do faze punog cvetanja je zabeležen 'plato', odnosno skoro konstantna količina aNDF, ADF, ADL i celuloze. Prikazane su korelacije između svih parametara ćelijskog zida. Jednačina aNDF = 36.713 + 1.181 × ADF je preporučena za konverziju ADF u aNDF u lucerki

Uticaj stepena sabijanja i inokulacije na biohemijske promene u silažama lucerke

The effect of different levels of compression (A1 = 420 gdm-1, A2 = 560 gdm-1) and inoculation (B1 = no inoculant, B2 = with inoculant) on changes in chemical composition, proteolysis and quality of lucerne silage was investigated in this paper. Based on the results of chemical analysis we found that in silages with more compressed material there was a reduction in the amount of ammonia nitrogen, soluble nitrogen and acetic acid, and increased content of protein nitrogen ('true'protein) and production of lactic acid (p lt 0.05). With the inoculation of the ensiling material the production of ammonia nitrogen and acetic acid was reduced but the content of lactic acid and acidity was increased (p lt 0.05). The interaction of both investigated factors (A×B) induced a decrease in the proteolysis degree, increase of lactic acid production and decrease in acetic acid production, and decrease in pH values (p lt 0.001) in investigated silages. The investigated factors had less influence on the chemical composition of lucerne material, and the significant variations were observed in fat and NFE contents. On the basis of this investigation the degree of compression is the most important parameter in ensiling technology. With the adequate compression and reduction of air in the starting material, the aerobic phase is reduced and the activity of proeolytic enzymes is decreased. In practice the special attention should be given to factors on which directly or indirectly the level of compression of ensiled material depends: wilting, cutting, object selection and/or selection of machines used for compression.U radu je ispitivan uticaj različitog stepena sabijanja (A1 = 420 gdm-1, A2 = 560 gdm-1) i inokulacije (B1 = bez inokulanta, B2 = sa inokulantom) na promene parametara hemijskog sastava, proteolize i kvaliteta silaže lucerke. Na osnovu rezultata hemijskih analiza utvrđeno je u silažama od bolje sabijenog materijala smanjenje količine amonijačnog i rastvorljivog azota, kao i sirćetne kiseline, i povećanje količine proteinskog azota ('pravog' proteina) i mlečne kiseline (p lt 0,05). Inokulacijom siliranog materijala smanjena je produkcija amonijačnog azota i sirćetne kiseline i istovremeno povećana produkcija mlečne kiseline i kiselost silaža (p lt 0,05). Interakcijom ispitivanih faktora (A×B) došlo je do smanjenja stepena proteolize u silažama, povećanja produkcije mlečne kiseline i smanjenja količine sirćetne kiseline, a time i smanjenja pH vrednosti (p lt 0,001). Ispitivani faktori su bili od manjeg značaja za promene parametara hemijskog sastava hraniva pa su signifikantno varirali samo količina masti i BEM-a. Na osnovu izvedenih ispitivanja može se zaključiti da je stepen sabijanja najvažnija mera u tehnologiji siliranja hraniva. Adekvatnim sabijanjem skraćuje se trajanje aerobne faze i ograničava delatnost proteilitičkih enzima. U praksi treba posvetiti maksimalnu pažnju faktorima od kojih direktno ili indirektno zavisi stepen sabijenosti siliranog materijala: stepenu provenulosti, dužini seckanja, izboru tipa objekta za siliranje i/ili izboru mehanizacije za sabijanje (gaženje ili baliranje)

Kritički osvrt na primenu zakona o strateškoj proceni uticaja na životnu sredinu u prostornom i urbanističkom planiranju

Considerations of the environmental protection in spatial and urban plans in past decade have been based on propositions of the Law on Environmental protection, Law on planning and arrangement of settlements, and Spatial plan of Serbia, because other legislation did not offered suitable instruments. Recently adopted the Law on environmental protection introduce a new instrument for environmental protection in planning - the strategic environmental impact assessment (SEIA), which was regulated by the separate Law on strategic environmental impact assessment. Key characteristics of the law on strategic environmental impact assessment were analyzed in this paper, as well as problems and limitations in implementation of that law on spatial and urban plans.Razmatranje zaštite životne sredine u prostornim i urbanističkim planovima u protekloj deceniji zasnivalo se na propozicijama Zakona o zaštiti životne sredine, Zakona o planiranju i uređenju prostora i naselja i Prostornom planu Srbije, budući da drugi zakoni nisu ponudili pogodne instrumente. Nedavno usvojeni Zakon o zaštiti životne sredine uvodi novi instrument za zaštitu životne sredine u planiranju -'Stratešku procenu uticaja na životnu sredinu' (SPU), koja je regulisana posebnim Zakonom o strateškoj procenu uticaja na životnu sredinu. U radu se analizira značenje ključnih karakteristika strateske procene i odredbi zakona o strateškoj proceni, kao i problemi i ograničenja u primeni tog zakona na prostorne i urbanističke planove

Study on a standard for grounding systems realization

Grounding systems of objects inside power facilities are very often realized as structures consisting of protective electrodes’ system placed in the object foundation, and neutral electrodes’ system placed at a specified distance from the object. Official standards and publications recommend a minimal value for the distance between the protective and the neutral part of grounding structures, so that the influence of one on another can be neglected. We analyze several practical implementations of grounding structures and demonstrate that the minimal distance is actually much smaller than that recommended by the standards

Otvorene inovacije u funkciji održivosti životne sredine i zelene tranzicije: mogućnosti za primenu

Ugrožavanje životne sredine, zagađenje vazduha, emisija gasova sa efektom staklene bašte i klimatske promene samo su neki od ekoloških problema prouzrokovani ljudskim ponašanjem, sa kojima se čitav svet poslednjih decenija susreće kao najvećim globalnim ekološkim izazovima. Istovremeno, razvoj Internet inteligentnih uređaja i digitalizacija kao dinamični procesi koji proteklih decenija intenzivno napreduju, omogućili su da se primenom otvorenih inovacija zasnovanih na crowdsourcingu mogu uspešno rešavati problemi u različitim oblastima delovanja i izvan tradicionalnih i klasičnih okvira inovacija. Osnovno istraživačko pitanje koje autori postavljaju u ovom radu je da li se primenom otvorenih inovacija zasnovanih na Internet inteligentnim uređajima i digitalnom razvoju, može doprineti zaštiti životne sredine i zelenoj tranziciji. U radu se analiziraju istraživanja i primena otvorenih inovacija u širokom spektru privrednih i društvenih oblasti, kojima se unapređuje visokokvalitetni zeleni razvoj. Cilj rada je da se na osnovu analize utvrdi može li se primenom otvorenih inovacija zasnovanih na Internet inteligentnim uređajima i digitalizaciji doprineti održivom razvoju životne sredine i zelenoj tranziciji. Na osnovu primera pozitivnog uticaja otvorenih inovacija na zelenu tranziciju, autori istražuju i definišu oblasti i načine na koje one mogu da doprinesu razvoju održivosti životne sredine, kao i moguće probleme i ograničenja u toj interakciji. Autori definišu i pravce budućih aktivnosti i razvoja otvorenih inovacija u funkciji bržeg razvoja i primene zelene tranzicije. Zaključak istraživanja je da se primenom otvorenih inovacija zasnovanih na digitalnom razvoju u različitim oblastima može doprineti zelenoj tranziciji i da interakcija otvorenih inovacija i zelene tranzicije omogućava razvoj održivosti životne sredine na globalnom nivou