Produkcija makrozoobentosa u reci Rači uzvodno i nizvodno od pastrmskog ribnjaka

Biomasa (produkcija) makrozoobentosa je odabrana kao osnovni pokazatelj za praćenje promena kvantitativnog sastava naselja dna na lokalitetima uzvodno i nizvodno od pastrmskog ribnjaka u reci Rači. Istraživanje sekundarne produkcije makrozoobentosa reke Rače sa sedam lokaliteta, obavljeno je u periodu 2011. (april, jun, septembar, oktobar, decembar) i 2012. godine (februar i maj). Dominantne grupe u biomasi makrozoobentosa su Hirudinea (Annelida), Mollusca, Gammaridae (Crustacea) i Trichoptera (Insecta). Vrednosti biomase zoobentosa kretale su se u svim mesecima istraživanja u intervalu od 3,2001 g/m2, na lokalitetu RČ2 (u februaru) ,do 216,7120 g/m2, na lokalitetu RČ3 (u februaru). Biomasa faune dna najveća je u svim mesecima istraživanja na lokalitetu RČ3, koji je lociran nizvodno od pastrmskog ribnjaka. Na ovom lokalitetu biomasa makroinvertebrata se kretala od 87,8643 g/m2 (u aprilu 2011. godine) do 216,7120 g/m2 (u februaru 2012. godine)

Eksperimentalno modeliranje i numerička FE analiza procesa izvlačenja sa stanjenjem čeličnih traka

This paper deals with analysis of steel strip ironing using experimental modelling and numerical FE simulation. Since both approaches are complementary to each other, numerous results were obtained that enable complete analysis of the processes within deformation zone. Device for modelling of strip ironing has been developed for experimental testing. Die cone angle, holding force, contact friction conditions on the die and the punch side were varied, due to easily replaceable working elements of the device. Friction coefficient values used in numerical FE simulations were determined based on measured values of forces on die and punch, as well as forming load on machine. Experimentally obtained results were confirmed by FE analysis that provided additional information about physics of the process itself within deformation zone. Presented research results point to coherent influences of process factors on tensile wall stress values, which represents key indicator for efficiency of forming, resulting in recommendations for efficient process management.Rad se bavi analizom procesa izvlačenja sa stanjenjem čelične trake, primjenom eksperimentalnog modeliranja i numeričkih FE simulacija. Kako su oba pristupa komplementarna, dobiveno je mnoštvo rezultata za sveobuhvatnu analizu procesa u deformacijskoj zoni. Za potrebe eksperimentalnog modeliranja razvijen je uređaj za modeliranje procesa izvlačenja sa stanjenjem trake. Zahvaljujući lako izmjenjivim radnim elementima uređaja, varirane su vrijednosti kuta matrice, sile držanja, uvjeti kontaktnog trenja na strani izvlakača i matrice. Vrijednosti faktora trenja, korištenih u numeričkim FE simulacijama su određene na osnovu izmjerenih vrijednosti sila na matrici i izvlakaču, kao i ukupne sile na stroju. Eksperimentalno dobiveni rezultati potvrđeni su numeričkom FE analizom, pri čemu je ona dala dodatne informacije o samoj fizici procesa u deformacijskoj zoni. Prikazani rezultati istraživanja ukazuju na spregnute utjecaje analiziranih faktora procesa na iznos rasteznog naprezanja u stijenki matrice, koji predstavlja ključni pokazatelj uspješnosti obrade, iz kojih proizlaze preporuke za uspješno upravljanje procesom

A Distributed Catalog for Digitized Cultural Heritage

International audiencePeer-to-peer networks have emerged recently as a flexible decentralized solution to handle large amount of data without the use of high-end servers. In this paper we present a distributed catalog built up on an overlay network called "Synapse". The Synapse protocol allows interconnection of different overlay networks each of them being an abstraction of a "community" of virtual providers. Data storage and data retrieval from different kind of content providers (i.e. libraries, archives, museums, universities, research centers, etc.) can be stored inside one catalog. We illustrate the concept based on the Synapse protocol: a catalog for digitized cultural heritage of Serbia

Kvalitet vode u reci Raškoj na osnovu organizama zoobentosa i zooplanktona kao bioindikatora

U cilju ispitivnja kvaliteta vode reke Raške, organizmi zoobentosa i zooplanktona korišćeni su kao bioindikatori. Istraživanje je sprovedeno od aprila 2011. godine do maja 2012. godine, u vremenskim intervalima od dva meseca. Odabrano je ukupno pet lokaliteta na dužinini toka od 2.5 km. Između drugog i trećeg lokaliteta lociran je pastrmski ribnjak, čiji je uticaj na zajednice organizama praćen. Na lokalitetima koji su obuhvaćeni istraživanjima konstatovano je 57 taksona makrozoobentosa (34 vrste, 21 roda, 1 familija i 1 klasa) i 75 taksona zooplanktona (58 vrsta, 15 rodova, 1 red i 1 klasa). Srednje vrednosti indeksa saprobnosti ukazivale su na manje razlike u dobijenim vrednostima korišćenjem zoobentosa i zooplanktona. Na osnovu saprobioloških analiza, kada su kao bioindikatori korišćeni organizmi bentosa, kvalitet vode u reci Raškoj je druge klase kvaliteta, ili na prelazu između prve i druge klase, uglavnom na lokalitetima iznad ribnjaka. Organizmi zooplanktona su pokazali da voda celom dužinom toka pripada prvoj klasi kvaliteta. Najmanje vrednosti indeksa saprobnosti zabeležene su na prvom, referentnom lokalitetu 1.453±0.098 (zooplankton), a najviše na četvrtom lokalitetu 1.88±0.021 (zoobentos). Na lokalitetu ispod ribnjka, gde je zabeležen pad u koncentraciji kiseonika, dominiraju organizmi bentosa koji tolerišu veći stepen organskog zagađenja (Chironomidae, Oligochaeta, Simuliidae). Iako su koncentracije ukupnog fosfora i ortofosfata rasle od trećeg ka petom lokalitetu, njihove koncentracije nisu premašivale dozvoljene vrednosti za salmonidne vode. Međutim, srednje vrednosti koncentracije nejonizovanog amonijaka (NH4+) su iznad referentnih vrednosti na trećem i četvrtom lokalitetu. Razlog nepodudaranja vrednosti indekasa saprobnosti za dve istraživane grupe, može biti usled nestabilnih zooplanktonskih zajednica zbog izraženog efekta drifta, kao i usled činjenice da će zbog procesa sedimentacije dospelih organskih materija, organizmi dna biti izloženiji njihovom uticaju. Zajednice bentosa, kao znatno stabilnije i u vremenu i u prostoru, pogodnije su za procenu kvaliteta tekućih voda

Effect of Neuromuscular Training Program on Quality of Life After COVID-19 Lockdown Among Young Healthy Participants: A Randomized Controlled Trial

Study in the period of coronavirus disease 2019 (COVID-19) lockdown and the effect of different exercise training programs on the quality of life (QoL) dimension are limited. This randomized control study as a part of which the impact of an 8-week neuromuscular training program on the 90 healthy young individuals’ QoL after COVID-19 lockdown was assessed using a short form of the WHOQOL-BREF questionnaire comprising of four domains (physical health, psychological health, social relations, and the environment). The intervention group (NT) (n = 47) took part in a neuromuscular training program consisting of dynamic neuromuscular stabilization and whole-body vibration training. In contrast, the control group (CG) (n = 43) did not participate in any programmed physical activity. From pre- to post-intervention test, the NT group significantly and substantially improved [mean change (95% CI)] all the QoL domains, physical for 12.78 scores (8.89, 16.64), psychological for 13.12 scores (9.51, 16.74), social relationships for 20.57 scores (16.12, 25.02), and environmental for 24.40 scores (21.45, 27.35). These results suggest that the NT program could enhance QoL in young and healthy participants following COVID-19 lockdown

Auto-organisation des colonies de Saccharomyces cerevisiae

The natural environment of yeast is often a community of cells but researchers prefer to study them in simpler homogeneous environments like single cell or bulk liquid cultures, losing insight into complex spatiotemporal growth, differentiation and self-organization and how those features are intertwined and shaped through evolution and ecology. I developed a multi-layered microfluidic device that allows us to grow yeast colonies in spatially controlled dynamically structured changing environments from a monolayer of single yeast cells to a multi-layered colony. Colony growth, as a whole and at specific locations, is a result of the nutrient gradient formation within a colony through interplay of nutrient diffusion rates, nutrient uptake rates by the cells and starting nutrient concentrations. Once a limiting nutrient (e.g. glucose or amino acids) is depleted at a specific distance from the nutrients source the cells within a colony stop to grow. I was able to modulate this specific distance by changing the starting nutrient concentrations and uptake rates of cells. Colony gene expression patterns gave us information on specific micro environments formation and consequential development, differentiation and self-organization. I quantified the patterns of expression of seven glucose transporter genes (HXT1-7), each of them specifically expressed depending on the glucose concentration. This enabled us to reconstruct glucose gradients formation in a colony. I further followed the expression of fermentation and respiration specific genes and observed differentiation between two subpopulations. We also mapped other genes specific for different parts of carbohydrate metabolism, followed and quantified the spatiotemporal dynamics of growth and gene expression, and finally modelled the colony growth and nutrient gradient formation. For the first time, we were able to observe growth, differentiation and self-organization of S. cerevisiae colony with such an unprecedented spatiotemporal resolutionL’environnement naturel des levures est constitué d’une communauté de cellules. Les chercheurs, cependant, préfèrent étudier les levures dans des environnements plus simples et homogènes, comme des cultures en cellule unique ou en population, s’affranchissant ainsi de la complexité de la croissance spatiotemporelle, la différentiation, l’auto-organisation, ainsi que la façon dont ces caractéristiques sont formées et s’entrelacent à travers l’évolution et l’écologie. Nous avons mis en place un dispositif microfluidique multicouches permettant la croissance de colonie de levures dans des environnements dynamiques, spatialement structurés, contrôlés, partant d’une monocouche de levures à une colonie multicouches. La croissance des colonies, dans son ensemble comme à des positions spécifiques, est le résultat de la formation d’un gradient de nutriment au sein de celles-ci - gradient qui trouve son origine dans le différent taux de diffusion des nutriments, des taux d’absorption de ceux-ci par les cellules, ainsi que de leurs concentrations initiales. Lorsqu’un nutriment en quantité limitante (par exemple le glucose ou un acide aminé) est épuisé, à une distance spécifique de la source de nutriments, les cellules au sein de la colonie cessent de croitre. Nous avons été en mesure de moduler cette distance spécifique en variant la concentration initiale de nutriments ainsi que le taux d’absorption des cellules. Les motifs d’expression de gènes de la colonie nous ont donné des informations sur la formation de micro environnements spécifiques ainsi que sur le développement subséquent, la différentiation et l’auto-organisation. Nous avons quantifié les motifs d’expression de sept gènes de transport du glucose (HXT1-7), chacun exprimé spécifiquement suivant la concentration de glucose, ce qui nous a permis de reconstituer la formation de gradients de glucose au sein d’une colonie. En étudiant des gènes spécifiques de la fermentation et de la respiration, nous avons pu observer la différentiation en deux sous-populations. Nous avons de plus cartographié l’expression de gènes impliqués dans différentes parties du métabolisme des glucides, suivi et quantifié la dynamique spatio-temporelle de croissance et d’expression génétique et finalement modélisé la croissance de la colonie ainsi que la formation du gradient de nutriment. Pour la première fois, nous avons observé la croissance, la différentiation et l’auto-organisation des colonies de S. cerevisiae avec une résolution spatio-temporelle jusqu’à maintenant inégalé

Optimal preventive maintenance model of complex degraded systems: A real life case study

412-420This study presents a comparison of two models to find optimum maintenance policy of complex degraded systems. UsingMarkov processes, optimal value of mean time to preventive maintenance is determined by maximizing availability of completesystems. Models include a stochastic degradation process, random failures and a set of maintenance actions and their effects. A reallife case study is presented to illustrate implementation of models. A two-component transportation system for collecting wasteutilized by Public utility company, Mediana Niš, Serbia, is analyzed

A temporal epistemic logic with a non-rigid set of agents for analyzing the blockchain protocol

In this paper we provide a strongly complete axiomatization of a temporal epistemic logic in which non-rigid sets of agents are allowed. Using this framework, we prove a number of properties of the blockchain protocol with respect to the given set of axioms and premises