The synergistic effect of genomic and environmental stress in two populations of Drosophila subobscura.

Jedinke uzorkovane iz dva ekološki različita staništa, i hibridi nastali njihovim ukrštanjem (unutar-linijski, unutar-populacioni i među-populacioni) izlagane su povećanoj koncentraciji olova, čime je omogućeno da se utvrdi razlika u odgovoru jedinki različitog nivoa heterozigotnosti genoma na sredinski stres odnosno, testira hipoteza o heterozigotnoj superiornosti u stresnim uslovima i utvrdi populaciono specifičan odgovor na prisustvo olova. Sinergistički efekat stresa evaluiran je na tri nivoa: populacionom - analizom komponenti adaptivne vrednosti (dužina razvića i preživljavanje od jaja do adulta), morfološkom – analizom varijabilnosti veličine krila i biohemijskom - praćenjem ekspresije proteina toplotnog šoka. Rezultati su pokazali redukciju svih ispitivanih osobina kod inbredovanih jedinki i njihovo povećanje kod jedinki sa višim nivoom heterozigotnosti genoma, potvrđujući hipotezu heterozigotne superiornost koja se intenzivira u stresnim uslovima. Uočen je trend sinergističkog efekta genomskog i sredinskog stresa za komponente adaptivne vrednosti, koji je statistički značajan za veličinu krila, s obzirom da je najintenzivnija redukcija primećena kod inbredovanih jedinki u stresnim uslovima. Nije dobijen populaciono specifičan odgovor u prisustvu olova, ali je utvrđeno da na ishod međupopulacione hibridizacije u stresnim uslovima veliki uticaj ima poreklo ženke i evoluciona istorija njene prirodne populacije. Može se zaključiti da je održavanje genetičke varijabilnosti od velike važnosti za opstanak populacija, i da čak i nizak stepen inbridinga utiče na pad adaptivne vrednosti, naročito u stresnim uslovima sredine.The subject of this dissertation is population genetic analysis of synergistic effect of genomic and environmental stress in model species Drosophila subobscura. Individuals sampled from two ecologically distinct habitats, and their hybrids with different levels of genome heterozygosity (intra-line, intra-population and inter-population hybrids) were exposed to elevated concentrations of lead, aiming to test hypothesis of heterozygote superiority in stressful conditions and detect population specific response to lead pollution. Synergistic effect of stress was evaluated at three levels: population - through analysis of fitness components (development time and egg-to-adult survival), morphological - through analysis of variability in the wings size and biochemical – through the expression of heat shock protein. The results showed a reduction of all investigated traits in inbred individuals and their increase in those with higher levels of genome heterozygosity, confirming the hypothesis of heterozygote superiority which intensifies under stressful conditions. Analysis of fitness components indicates synergistic effect of genomic and environmental stress, and variance in wing size shows statistical significance, since the greatest reduction of all traits was observed in inbred groups. Population specific response to lead pollution was not detected, but significant influence of female origin on the outcome of between-population hybridization under stressful conditions was observed. It can be concluded that the maintenance of genetic variation is important for the survival of populations in changing environments, and even low levels of inbreeding lead to decline in adaptive value, especially in stressful environments

Development and static strength analysis of the modified military semi-trailer bearing structure

The development of a new semi-trailer presents a great challenge for designers, as well as the investment of a significant amount of money and time. Army vehicles have specific characteristics and allow certain flexibility in measure dimensions which can be defined according to the specific needs of customers. This paper presents the reconstruction and modification of an old semi-trailer with the aim to reduce manufacturing costs. The base for modification was a semi-trailer, 30 tones load bearing, which spent approximately 30 years in exploitation. According to the assessment of the state of the current bearing structure and materials, the vehicle owner decided, to retain half construction, reconstruct and develop another half to the specific purchaser's requests. The first step was to remove one-half of the construction which must be reconstructed by cutting. Furthermore, a 3D and numerical model of the bearing structure was formed. Static strength analysis of the modified vehicle structure was performed using an adequate software package and finite element method. Analysis was done for the different load cases and defined by valid standards and purchaser requests. Obtained results showed that modified vehicle structures can withstand defined loads without any permanent deformation. After producing 2D documentation, production of prototype semi-trailer was launched, and a vehicle was delivered and involved in exploitation. After a year of exploitation test, the modified bearing structure satisfied all required criteria and serial production can be started

Specifičnosti metodskog postupka u obradi regionalno-geografskih sadržaja u VII razredu osnovne škole

The institutionalized and hierarchically structured system that covers elementary, secondary and university education represents the framework of the sphere of formal education within whish the geographical education of every individual is developed. The system is formed by legal acts, curriculum and educational standards in a domain of student's achievements binding for all participants in the teaching process. With the aim of improving the teaching practice and achieving better effects the paper represents the specificities of methodical procedure in the treatment of the regional-geographical contents in the seventh grade of elementary school.Institucionalizovani i hijerarhijski struktuirani sistem koje pokriva osnovno, srednje i visoko obrazovanje predstavlja okosnicu sfere formalnog obrazovanja u čijim okvirima se obavlja geografsko obrazovanje i vaspitanje svakog pojedinca. Sistem je oblikovan pravnim aktima, nastavnim planom i programom i vaspitno-obrazovnim standardima koji su obavezujući za sve aktere nastavnog procesa. U cilju unapređivanja nastavne prakse i postizanja boljih efekata u radu su prezentovane specifičnosti metodskog postupka u obradi regionalno­geografskih sadržaja u sedmom razredu osnovne škole

Specifičnosti metodskog postupka u obradi regionalno-geografskih sadržaja u VII razredu osnovne škole

The institutionalized and hierarchically structured system that covers elementary, secondary and university education represents the framework of the sphere of formal education within whish the geographical education of every individual is developed. The system is formed by legal acts, curriculum and educational standards in a domain of student's achievements binding for all participants in the teaching process. With the aim of improving the teaching practice and achieving better effects the paper represents the specificities of methodical procedure in the treatment of the regional-geographical contents in the seventh grade of elementary school.Institucionalizovani i hijerarhijski struktuirani sistem koje pokriva osnovno, srednje i visoko obrazovanje predstavlja okosnicu sfere formalnog obrazovanja u čijim okvirima se obavlja geografsko obrazovanje i vaspitanje svakog pojedinca. Sistem je oblikovan pravnim aktima, nastavnim planom i programom i vaspitno-obrazovnim standardima koji su obavezujući za sve aktere nastavnog procesa. U cilju unapređivanja nastavne prakse i postizanja boljih efekata u radu su prezentovane specifičnosti metodskog postupka u obradi regionalno­geografskih sadržaja u sedmom razredu osnovne škole

Risk assessment of coupling system failure on train in current maintenance system

Development of new management approaches on the railway, based on risk management, with the adoption of standards EN 50126-1 and EN 50126-2 provide safety management processes for railway applications. Risk factors can be determined using different risk assessment methods like FMEA, FMECA, FTA etc. or their combination. The permissible risk values based on accepted values and defined preventive measures are designed on the current maintenance plan for freight wagons. Preventive measures are established for revision maintenance which is carried out every 4-6 years. Risk analysis of coupling system failure can be different depending on the time of analysis (regulations, exploitation conditions) and the applied maintenance practice. FMEC analysis applied to train coupling systems based on regulation shows different permissible risk values that don't match exploitation data

Relationship between chromosomal and mitochondrial DNA variability of Drosophila subobscura population from the Lazar's river canyon

The genetic structure of Drosophila subobscura population from the Lazar’s River Canyon (Serbia) was studied with respect to restriction site polymorphism of mitochondrial DNA and chromosomal inversion polymorphism. The aim was to shed more light on the role of cytonuclear interactions in shaping mitochondrial DNA variability in this species. Similar to other populations of D. subobscura two main haplotypes (I and II) were found, as well as less common ones that appeared at very low frequencies. The frequency distribution of haplotypes did not depart from neutrality. We did not find statistically significant linkage disequilibrium between the haplotypes belonging to haplogroups I and II and any of the chromosomal arrangements. However, when we compared the data in hereby analyzed population and two previously analyzed populations we observed that haplotype I is more frequent in populations where standard inversion arrangements are less frequent. Pattern of the observed mitochondrial variability could be influenced either directly by environmental variability or through environmentally specific cytonuclear coadaptation.U ovom radu analizirana je genetička varijabilnost restrikcionih mesta mitohondrijalne DNK, kao i varijabilnost inverzionog polimorfizma u populaciji Drosophila subobscura sakupljenoj u kanjonu Lazareve reke. Cilj je bio rasvetljavanje uloge citonuklearnih interakcija u oblikovanju varijabilnosti mitohondrijalne DNK. Utvrđeno je prisustvo dva dominantna haplotipa (I i II) kao i dva haplotipa niske učestalosti. Nije utvrđena statistički značajna neravnoteža vezanosti između haplotipova grupisanih u haplogrupe I i II i nijednog od hromozomskih aranžmana. Međutim, upoređivanjem podataka prethodno analiziranih populacija i populacije analizirane u ovom radu, primećuje se povećanje učestalosti haplotipa I sa smanjenjem učestalosti standardnih hromozomskih aranžmana. Ovakav obrazac ukazuje ili na direktan uticaj sredinskih činilaca na varijabilnost mitohondrijalne DNK ili na sredinski zavisnu citonuklearnu koadaptaciju.Projekat ministarstva br. 17301

The trend of train coupling failure on Serbian railways in 10 year period

This paper presents an analysis of train coupling failure on the Serbian Railways and displays a trend of characteristics over 10 year period. The impact of changes in the organization of exploitation and maintenance and led by the introduction of Entity in Charge of Maintenance (ECM) and reconstruction of Serbian railway company into 3 separate entities as well as some differences and aging in rolling stock induce certain changes in the parameters of train coupling failure. The analysis is done based on parameters of train configuration and driving specifications. Only freight trains with single traction locomotives are considered. The distribution of coupling failure along the train, driving regime and velocity is comparatively discussed related to the values from the previous period. Load status, as well as the length and mass of the trains in the extended collection, correspond to a certain distribution. Causes of failure and damages to coupling and draw gear indicate specific conditions leading to failure. Analysis significance helps the systematization of failure features and sets the ground for defining the parameters that impact failure and determining their quantification

Lactobacillus helveticus lafti l10 supplementation modulates mucosal and humoral immunity in elite athletes: a randomized, double-blind, placebo-controlled trial

To test the influence of probiotic supplementation on humoral immune response, a double-blind, placebo-controlled trial was conducted. Thirty athletes (24 males and 6 females, females: (V)over dotO(2)max 38.2 +/- 4.9 ml.kg(-1).min(-1), age 23.2 +/- 1.4 years; males: (V)over dotO(2)max 57.5 +/- 9.2 ml.kg(-1).min(-1), age 24.0 +/- 2.4 years, mean +/- SD) were randomized either to the probiotic group (Lactobacillus helveticus Lafti L10, 2 x 10(10) colony-forming units) or to the placebo group. Serum and saliva samples were collected at the baseline and after 14 weeks. Total and specific antibacterial antibody levels of IgM, IgG, and IgA classes were determined for different bacteria in the serum, and in saliva, total and specific antibacterial IgA levels were examined. Total IgM was elevated in both probiotic (18%, 15-20%; mean, 90% confidence interval; p = 0.02) and placebo group (35%, 22-47%; p = 0.02), without observed differences in changes between the groups. No significant changes in IgM levels specific for tested bacteria were found. Total IgG level was constant in both groups. A significant (16%, 22.8 to 35%, p = 0.04) reduction of anti-Enterococcus faecalis IgG was noted in the placebo group, in comparison with the probiotic group. There was a substantial decrease in total IgA level in the placebo group, when measured either in serum (15%, 12-18%, p = 0.04) or in saliva (35%, -1.4 to 53%, p = 0.03). Significantly reduced levels of serum anti-lactic acid bacteria IgA antibodies in the placebo group compared with the probiotic group were detected for Lactobacillus rhamnosus LA68 (24%, 5.8-42%, p = 0.02) and for L. rhamnosus LB64 (15%, 2.7-27%, p = 0.02). Probiotic administration could have beneficial effects on systemic humoral and mucosal immune responses

Experimental research of mechanical characteristics of railway vehicles safety coupling components

The coupling system provides a mechanical connection between European railway vehicles. Screw couplings are designed as a safety device in railway vehicles with coupling links and screw as two main components intended to break. Failure of these components is necessary when the load between vehicles is exceeded, otherwise more significant draw gear elements will fracture. The analysis of train break cases shows that the failure of the links occurs only in an approx. 6% of cases. Therefore, the links taken from exploitation after more than 30 years in operation were tested to determine their mechanical characteristics. Tensile testing was performed according to the ISO 6892-1 standard with a continual force and a minimal and maximal test speed prescribed by ISO 6892-1. The values of mechanical characteristics of coupling links are substantially improved during production after heat treatment by hardening and tempering. However, test results of mechanical characteristics didn’t meet all prescribed limits for the minimum requirements according to UIC 826. The current regulations of mechanical characteristics were not in force in time of link production. Examination of the tested links showed a ductile fracture and the cross-sectional area shows the planar stress state