Genetic bases of the evolution of organisms

Biological progress consists of the continuous increase of divergence with simultaneous maintenance and the increase of conformance (harmoniousness) of living systems. A mutual balance between divergence of forms and the degree of perfection of their structure and function indicates a level of the evolutionary development of a particular group of organisms, i.e. a level and prospects of their evolutionary progress. An enormous potential of combined genetic polymorphousness is reduced to adaptive landscapes of a limited number of developmental programmes that make actual units of inheritance and variability within each species

Serbian bioethics from an international perspective: Genetics and bioethics

Global interests in bioethics have increased drastically since the end of 20th century. The reason for this should be ascribed to a broad application of molecular-genetic methods introduced in human bio-medicine. This has, in turn, produced an involvement and development of numerous inter-disciplines, which have started to apply bioethics as a part of their own subject of interest. This article presents more than a decade of experience of teaching bioethics in our country, particularly under the auspices of the National Com­mittee for Bioethics of UNESCO-commission of Serbia

Dynamical modelling of hydraulic excavator considered as a multibody system

This paper considers the development of a plane multibody mechanical model of a hydraulic excavator simultaneously containing an open kinematic chain and closed loops. The Lagrange multiplier technique is used for modelling of the constrained mechanical systems. This approach is used for working out the dynamic equations of excavator motion in the case of performing transportation and digging operations. The excavator is considered as a rigid body system and detailed governing equations of the mechanical and hydraulic systems are presented. The performed verification and a typical digging task simulation show the applicability of the model for study of the excavator motion simulation. Simulation results of the machine’s response are provided. It is shown that the digging process considerably influences the mechanical and hydraulic system parameters. Such models can be used for training simulators, sizing components and system design.DFG, 325093850, Open Access Publizieren 2017 - 2018 / Technische Universität Berli

Upotreba biofizičkih metoda radi poboljšanja prinosa i kvaliteta poljoprivrednih proizvoda

Until as recently as a century ago, the exposure of biological systems to radiation was limited only to the natural sources. Today, however, a broad range of radiation types and doses have found a wide variety of uses and applications, so much so that it would be difficult to make a list of all the areas of human activity in which radiation is used for one purpose or another. The study of radiation effects on individuals and populations as a whole has become important only with the development of methods and sources of man-made radiation. Given that what is present in this case are physical effects on biological systems (living organisms), all these methods can be placed under the heading of biophysical influences. In the last 50 years, the effects of extremely low-frequency electromagnetic fields (ELF-EMF) have been studied with great diligence. These fields are the ones most commonly found in the human environment and they have been used in our studies in this field. The present paper provides a brief review of the literature data and our findings on the effects of ELF-EMF on various crop species using the RIES (Resonant Impulse Electromagnetic Stimulation) method, developed at the Faculty of Agriculture of the University of Novi Sad.Izloženost bioloških sistema u prirodi različitim vrstama zračenja, do pre samo jednog veka bila je ograničena isključivo na prirodne izvore. Danas, međutim, oblast primene najrazličitijih vrsta i doza zračenja je veoma raznovrsna, i teško je navesti sve oblike ljudske delatnosti u kojima se ona koristi. Proučavanje njihovih efekata na jedinke ili populacije u celini, dobilo je na značaju tek razvojem metoda i izvora zračenja koje je čovek stvorio. Obzirom da se radi o fizičkim dejstvima na biološke sisteme, tj. žive organizme, sve ove metode mogu se svrstati u domen biofizičkih delovanja. U poslednjih pedesetak godina se sa posebnom pažnjom ispituje uticaj EMF- a (Electromagnetic Field) ekstremno niskih frekvencija (ELF - Extemely Low Frequency), koja se najčešće nalaze u čovekovom okruženju, a koja se primenjuju i u našim ispitivanjima. U radu će biti dat kratak pregled dosadašnjih rezultata istraživanja autora i literaturnih podataka o dejstvu elektromagnetnog polja niskih frekvencija na gajene biljne vrste, primenom metode Rezonantno-Impulsne Elektromagnetne Stimulacije (RIES), razrađene na Poljoprivrednom fakultetu u Novom Sadu

Influential Factors in the Loading of the Axial Bearing of the Slewing Platform Drive in Hydraulic Excavators

The paper contains the results of the analysis of factors that influence the loading of the axial bearing of the slewing platform drive mechanism in hydraulic excavators. The following influential factors are considered: the operations of the excavator manipulation tasks, the number of drives in the slewing platform mechanism, and the configuration of the excavator kinematic chain. The importance of the influence of these factors is assessed on the basis of the comparison between certain equivalent loads of the platform drive bearing with the diagrams of allowed load capacities of available bearings. The equivalent loads of the platform drive mechanism bearing are determined using the approach of static and dynamic excavator simulation in the programs developed on the basis of the defined mathematical models of the excavator. The equivalent loads are given with regard to the duration of the manipulation task and in the form of a spectrum of equivalent loads determined in the entire operating area of the excavator. The analysis is performed for three different configurations of the kinematic chain of a tracked hydraulic excavator with the mass of around 100000 kg

Dynamical modelling of hydraulic excavator considered as a multibody system

Rad se bavi razvojem mehaničkog modela hidrauličnog bagera od više tijela koji u isto vrijeme sadrži otvoreni kinematički lanac i zatvorene petlje. Za modeliranje ograničenih mehaničkih sustava primijenjena je tehnika Lagrangeova faktora. Taj se pristup primjenjuje za dobivanje dinamičkih jednadžbi kretanja bagera kod obavljanja prijenosa i operacija kopanja. Bager se smatra sustavom krutog tijela i predstavljaju se detaljne jednadžbe za uređenje mehaničkih i hidrauličnih sustava. Izvršena provjera i simulacija tipičnog kopanja pokazuju primjenjivost sustava za proučavanje simulacije kretanja bagera. Daju se simulacijski rezultati reakcije stroja. Pokazano je da postupak kopanja znatno utječe na parametre mehaničkog i hidrauličkog sustava. Takvi se modeli mogu koristiti za obučavanje simulatora, dimenzioniranje sastavnih dijelova i dizajniranje sustava.This paper considers the development of a plane multibody mechanical model of a hydraulic excavator simultaneously containing an open kinematic chain and closed loops. The Lagrange multiplier technique is used for modelling of the constrained mechanical systems. This approach is used for working out the dynamic equations of excavator motion in the case of performing transportation and digging operations. The excavator is considered as a rigid body system and detailed governing equations of the mechanical and hydraulic systems are presented. The performed verification and a typical digging task simulation show the applicability of the model for study of the excavator motion simulation. Simulation results of the machine’s response are provided. It is shown that the digging process considerably influences the mechanical and hydraulic system parameters. Such models can be used for training simulators, sizing components and system design

Capacities for population-genetic variation and ecological adaptations

In contemporary science of population genetics it is equally complex and important to visualize how adaptive limits of individual variation are determined, as well as to describe the amount and sort of this variation. Almost all century the scientists devoted their efforts to explain the principles and structure of biological variation (genetic, developmental, environmental, interactive, etc.), basing its maintenance within existing limits mostly on equilibria proclaimed by Hardy-Weinberg rules. Among numerous model-organisms that have been used to prove these rules and demonstrate new variants within mentioned concepts, Drosophila melanogaster is a kind of queen that is used in thousands of experiments for almost exactly 100 years (CARPENTER 1905), with which numerous discoveries and principles were determined that later turned out to be applicable to all other organisms. It is both, in nature and in laboratory, that Drosophilids were used to demonstrate the basic principles of population-genetic variation that was later applied to other species of animals. In ecological-genetic variation their richness in different environments could be used as an exact indicator of the status of a determined habitat, and its population-genetic structure may definitely point out to a possibility that specific resources of the environment start to be in danger to deteriorate, or to disappear in the near future. This paper shows clear-cut differences among environmental habitats, when populations of Drosophilidae are quantitatively observed in different wild, semi-domestic and domestic environments, demonstrating a highly expressed mutual dependence of these two parameters. A crucial approach is how to estimate the causes that determine the limits of biological, i.e. of individual and population-genetic variation. The realized, i.e. adaptive variation, is much lesser than a total possible variation of a polygenic trait, and in this study, using a moderately complex gene-enzyme system, is estimated to be smaller than 0.2%. For an allozymic system based on 9 loci at three D. melanogaster chromosomes, the estimate is that chromosomal types are reduced, on the average, to ca. 3% during meiotic divisions, and that available gene-enzyme combinations are reduced further 15 times in gamete selection. So finalized metabolic or adaptive developmental programs are emphasized to be the basic targets of Darwinian selection, rather than chromosomes or individual genes, that are involved in these programs

Fitness of Allozyme Variants in DROSOPHILA PSEUDOOBSCURA. I. Selection at the PGM-1 and ME-2 Loci

We have studied in Drosophila pseudoobscura the effect of allozyme variation on seven fitness components: female fecundity, egg hatchability, egg-to-adult survival under near-optimal and under competitive conditions, rate of development under near-optimal and under competitive conditions, and mating capacity of males. Three genotypes at each of two loci, Pgm-1 and Me-2, have been studied in various combinations. These two loci are highly polymorphic in natural populations of D. pseudoobscura. Statistically significant differences involving one or more genotypes exist for all components of fitness. No single genotype is best for all fitness components; rather the relative fitnesses of genotypes are reversed when different parameters are considered, or when they are studied in different environmental conditions. Also, the average egg-to-adult survival and rate of development are better when different genotypes are reared together than when they occur in pure culture. Four different modes of selection have been uncovered by our experiments. These forms of selection may account for the persistence of the two allozyme polymorphisms in nature, and for previously observed seasonal fluctuations of the allelic frequencies in natural populations

Influential Factors in the Loading of the Axial Bearing of the Slewing Platform Drive in Hydraulic Excavators

The paper contains the results of the analysis of factors that influence the loading of the axial bearing of the slewing platform drive mechanism in hydraulic excavators. The following influential factors are considered: the operations of the excavator manipulation tasks, the number of drives in the slewing platform mechanism, and the configuration of the excavator kinematic chain. The importance of the influence of these factors is assessed on the basis of the comparison between certain equivalent loads of the platform drive bearing with the diagrams of allowed load capacities of available bearings. The equivalent loads of the platform drive mechanism bearing are determined using the approach of static and dynamic excavator simulation in the programs developed on the basis of the defined mathematical models of the excavator. The equivalent loads are given with regard to the duration of the manipulation task and in the form of a spectrum of equivalent loads determined in the entire operating area of the excavator. The analysis is performed for three different configurations of the kinematic chain of a tracked hydraulic excavator with the mass of around 100000 kg

Chromosomal inversion polymorphism of Drosophila subobscura from south-eastern part of Europe

Five Drosophila subobscura populations from south-eastern Europe were investigated with respect to chromosomal inversion polymorphism. They belong to central European populations and their gene arrangement frequencies are in accordance with latitudinal variation observed in this species. The new complex gene arrangement A(2+8+9), found in one of the populations analysed, may be specific for the southern Balkan refugium. A general tendency of gene arrangement frequencies to exhibit some southern characteristics was found for some of the autosomal standard arrangements.nul