Feasibility study of a current mode gamma radiation dosimeter based on a commercial pin photodiode and a custom made auto-ranging electrometer

An experimental study has been conducted to evaluate the feasibility of a current mode gamma radiation dosimeter, consisting of a commercial PIN photodiode as a radiation sensor, and a custom made auto-ranging electrometer for real-time measurement of the PIN photodiode’s response under radiation exposure. The radiation induced direct current response for single PIN photodiodes with different active areas, as well as for multiple PIN photodiodes connected in parallel, has been investigated. Three types of commercial silicon PIN photodiodes have been chosen for evaluation - S1223, BPW34, and PS100-6-CER2 PIN. During the experiment, five samples have been tested - three samples made of single PIN photodiodes (one sample of each photodiode type) and two samples formed by connecting multiple photodiodes in parallel (two BPW34 photodiodes in parallel and four BPW34 photodiodes in parallel). The samples have been irradiated with a 60Co gamma ray source and the relations between the induced photocurrent and the dose rate, and between the accumulated charge and the absorbed dose, have been determined. For measuring the photodiodes response, a custom made auto-ranging electrometer controlled by a personal computer, and capable of measuring direct currents from 50 pA to 10 mA with relative error less than 2.5%, has been used. Obtained results have shown very good linearity between the dose rate and the induced photocurrent for dose rates ranging from 0.93 Gy/h to 67 Gy/h. Also, very good linearity has been observed between the accumulated charge and the absorbed dose for all tested samples, within the investigated range of absorbed doses from 472 mGy to 3.3 Gy. On the basis of the obtained results, a simple model has been derived, enabling the estimation of the photodiode’s current response as a function of the dose rate and the photodiode’s geometry (active area and depletion layer width). [Projekat Ministarstva nauke Republike Srbije, br. 43011

Morphological variation of kinetic head skeleton and pileus in snake from the genus Natrix (N. natrix and N. tessellata)

Većina dosadašnjih istraživanja strukture i obrazaca varijabilnosti glavenog skeleta odnosila su se na grupe sa akinetičkom lobanjom. Istraživanje kinetizma u okviru glavenog skeleta zmija može doprineti boljem razumevanju odnosa razvojne i funkcijske integracije, uticaja alometrije na varijabilnost oblika i morfološku integraciju glavenog skeleta, promena oblika tokom ontogenije, kao i morfološke divergencije između polova. Pored toga, analizama varijabilnosti pileusa može se steći uvid u opštu sliku varijabilnosti glavenog regiona. Osnovni zadatak ove disertacije je utvrđivanje obrazaca morfološke varijabilnosti i faktora koji utiču na varijabilnost glavenog skeleta i pileusa kod dve sestrinske vrste zmija iz roda Natrix (belouške, N. natrix i ribarice, N. tessellata) primenom metoda kompjuterizovane tomografije i geometrijske morfometrije. Rezultati su pokazali da se belouška i ribarica razlikuju u veličini i obliku elemenata glavenog skeleta. Uočene razlike najverovatnije odslikavaju razlike u tipu i veličini plena, sredini u kojoj love, strategijama lova i sposobnostima držanja i gutanja plena. Polni dimorfizam u veličini i obliku elemenata glavenog skeleta veoma je izražen kod belouške i ribarice. Kod obe vrste moždana čaura i elementi trofičkog aparata su visoko integrisani, dok se kosti njuške ponašaju kao zasebni moduli. Funkcija najviše doprinosi integrisanosti elemenata glavenog skeleta. Utvrđeno je da se tek rođene belouške i ribarice razlikuju u obliku pileusa, dok se unutar vrsta polni dimorfizam u obliku pileusa ispoljava tek kod adulata. Između moždane čaure i pileusa ustanovljeni su visoki nivoi korelisanosti, kako za veličinu, tako i za oblik.Most of the previous investigations on the structure and patterns of cranial skeletons variability were done in groups with akinetic skull. Research of snake’s kinetic cranial skeleton can provide a better understanding of the relationship between developmental and functional integration, influence of allometry on shape variation and morphological integration of the cranial skeleton, shape changes during ontogeny, as well as morphological divergence between the sexes. In addition, analysis of pileus variability may provide insight into general pattern of head variability. The main aim of this thesis was to define the patterns of morphological variability and factors that affect the variability of head skeleton and pileus in two sister snakes species from the genus Natrix (Grass snake, N. natrix and Dice snake, N. tessellata) using the methods of computed tomography and geometric morphometrics. The results showed that N. natrix and N. tessellata differ in size and shape of cranial elements. Observed differences probably reflect differences in the type and size of the prey, hunting environment and strategies, handling abilities and prey swallowing. Sexual dimorphism in size and shape of cranial elements are pronounced among Grass and Dice snakes. In both species, braincase and elements of the trophic apparatus are highly integrated, while the bones of the snout can be considered as separate modules. The function is the main factor of morphological integration between cranial elements. Hatchlings of Grass and Dice snakes differed in pileus shape, while sexual dimorphism in pileus shape was detected in adults only. For both size and shape, high levels of correlation between braincase and pileus were estimated

Agroterrorism as a current challenge

nem

Eradikacija Helicobacter pylori kod bolesnika bez gastričkih simptoma koji imaju rekurentni aftozni stomatitis - pilot studija

Background/Aim. Helicobacter (H.) pylori is a widespread bacterium and its involvement in pathogenesis of gastric diseases is well-known. However, H. pylori role in etiology of other histologically similar conditions, especially recurrent aphthous stomatitis (RAS) is still controversial. Research regarding H. pylori and its association with RAS, as well as the treatment options were always conducted on patients with diagnosed gastric problems. The aim of this study was to determine whether H. pylori is present in the oral cavity of patients suffering from RAS but without any symptoms or medical history of gastric disease. Methods. A total of 15 patients with RAS participated in the study. None of the participants suffered from any gastrointestinal disorders. Two dental plaque samples from each participant were collected. The first was analyzed using rapid urease test and the second one was put in transport medium and sent for cultivation. The sensitivity of H. pylori to antibiotics was established using disk diffusion method of sensitivity testing for every patient individually and adequate therapy was prescribed. Results. Before the treatment the mean annual recurrence rate of RAS was 8.1 ± 2.1, with the average number of lesions being 3.9 ± 1.9. During the 12-month observation period after the eradication therapy, none of the patients reported recurrence of aphthous lesions. The treatment was successful in all cases. Conclusion. This study shows that RAS can be effectively treated by successful eradication of oral H. pylori, and that RAS could be possibly considered as an early warning sign of potential gastric infection by H. pilory.Uvod/Cilj. Helicobacter (H.) pylori je široko rasprostanjena bakterija i njen uticaj na nastanak gastričkih oboljenja vrlo dobro je dokumentovan. Međutim, uloga H. pylori u patogenezi histološki sličnih oboljenja, posebno rekurentnog aftoznog stomatitisa (RAS), nije dovoljno istražena. Dosadašnje studije, u kojima je ispitivana veza između H. pylori i RAS, kao i moguće terapijske opcije, bile su usmerene ka bolesnicima sa prethodno dijagnostikovanim gastričkim smetnjama. Cilj ovog istraživanja bio je da se utvrdi da li je H. pylori prisutan u usnoj duplji i kod bolesnika bez simptoma i istorije gastričkih oboljenja koji pate od RAS. Metode. U studiji je učestvovalo 15 bolesnika koji pate od RAS. Bolesnici nisu imali smetnje vezane za gornji deo digestivnog trakta. Po dva uzorka dentalnog plaka prikupljena su od svakog bolesnika. Jedan plak je ispitivan uz pomoć brzog ureaza testa, dok je drugi stavljen u transportni medijum i poslat na kultivaciju. Osetljivost H. pylori na antibiotike određivana je uz pomoć antibiograma za svakog bolesnika posebno i, u skladu sa rezultatima, prepisivana je odgovarajuća terapija. Rezultati. Pre lečenja prosečan broj epizoda RAS tokom godine iznosio je 8,1 ± 2,1, sa prosečno 3,9 ± 1,9 aftoznih lezija. Tokom 12-mesečnog perioda nakon eradikacione terapije, ni kod jednog bolesnika nije došlo do ponovne pojave afti. Terapija je bila uspešna kod svih bolesnika. Zaključak. Rezultati ovog istraživanja pokazuju da se RAS može uspešno lečiti eradikacijom H. pylori i da se sama pojava RAS može posmatrati kao rano upozorenje na moguću gastričku infekciju

Possible reproduction of the red-eared slider, Trachemys scripta elegans (Reptilia: Testudines: Emydidae), in Serbia, under natural conditions

Sjeverno-američka vrsta kornjače, Trachemys scripta elegans, danas je jedna od najpopularnijih kućnih ljubimaca širom Svijeta. Ipak, ako joj se omogući bijeg u prirodna staništa, postaje vrlo velik problem i prijetnja domaćoj barskoj kornjači i generalno vodenim životinjama. U ovom radu, po prvi put, izvještavamo o slučaju potencijalne reprodukcije crvenouhe kornjače u prirodnim uvijetima na području sjeverne i centralne Srbije. U srpnju 2014. Pronašli smo dva tek izlegla mladunca crvenouhe kornjače u blizini odvodnog kanala u selu Borča (okolica Beograda). Sudeći prema njihovoj duljini tijela i generalnim karakteristikama (blatni oklop, zabljeni karapaks), može se ustvrditi da su se tek izlegli vrlo blizo mjesta pronalaska.The North American chelonian, Trachemys scripta elegans, is still among the most popular pets worldwide. However, if released into natural water bodies outside of its natural distribution range it becomes a great nuisance and threat to native freshwater turtles and other aquatic wildlife. We report, for the first time, on the case of possible reproduction of the red-eared sliders under natural conditions in north-central Serbia. In July 2014 we found two red-eared slider hatchlings near the canal in the settlement of Borča near the Serbian capital. Judging by their body sizes and appearance (muddy shells, curved carapace), they had recently hatched near the place where they were found

Treatment of obstructive sleep apnea patients using oral appliances: Our experiences

Background/Aim. Obstructive sleep apnea (OSA) is one of the most prevalent sleep disorders. It is recognized as a serious risk factor for car and workplace accidents due to daytime sleepiness, and factor for coronary heart diseases and stroke. The aim of this study was to examine the effectiveness of oral appliances for mandibular advance in treating mild to moderate OSA. Methods. A total of 15 patients were included in this study, all diagnosed with mild or moderate OSA. Oral appliances were custom made for each patient in protrusive position at 50% of maximum mandibular advancement. The patients were given instructions not to sleep on their backs and avoid alcohol consumption during the study as these are the factors that can contribute to symptoms progression. Results. Complete and partial treatment success was achieve in 14 of the patients. Apnea-hypopnea index values were significantly lower (p < 0.05) at the end of a 6-month observation period compared to those at the treatment beginning. A great improvement in symptoms was observed, with daytime sleepiness index values significantly reduced already within the first month of the treatment. Conclusion. Treatment of obstructive sleep apnea with oral appliances has proven successful. Patients were comfortable using oral appliances and were ready to wear them for prolonged period of time. Use of oral appliances is very common in the world and should not be discarded. They are also very comfortable, practical and affordable comparing to continuous positive airway pressure (CPAP) apparatus, not to mention surgery. Use of oral appliances is safe and very well tolerated, and ought to be offered to patients with OSA

Amphibian and reptile road mortality in the protected area of Obedska Bara, Serbia

Millions of animals are roadkilled every year. Amphibians and reptiles are among the most prone to roadkill, especially near ponds and wetlands. We examined the impact of traffic on amphibian and reptile populations on the edge of Special nature reserve “Obedska bara”, Serbia. The aim of our study was to examine the temporal and spatial patterns of amphibian and reptile road mortality. From March to December 2018, we surveyed the road on foot for roadkills on a road section of 4.2 km, with two different habitat types (forest-pond and agricultural area-pond). Within 32 fieldwork days, we recorded 20457 roadkills (nine amphibian and eight reptile species). Amphibians (93%) were more vulnerable to traffic than reptiles (7%). Specimens of Pelophylax esculentus complex are the most frequently killed amphibians, followed by Pelobates fuscus, while specimens of Natrix natrix were the most frequently killed reptile species, followed by Emys orbicularis. The numbers of killed amphibians and reptiles varied with the season, indicating that species do not have the same roadkill patterns among the different seasons. Amphibian roadkills were the most frequent during the summer, while reptile roadkills were the most frequent in spring and late summer. Habitat type significantly affected the vulnerability of animals on roads. In addition to the different number of individuals killed in two different habitat types (higher in forest habitat), there was a difference in species composition. This study indicates that detailed monitoring and actions that will mitigate road mortality are urgently needed in the Special nature reserve “Obedska bara“

Influence of cadmium chloride on the frequency of micronuclei in da and AO rats

Heavy metal cadmium (Cd), a well-known environmental hazard, exerts a number of toxic and genotoxic effects. Experimental animals, Albino Oxford (AO) and Dark August (DA) rat strains, were treated intraperitoneally with three different concentrations of cadmium chloride (CdCl2): 0.5, 1, and 2 mg CdCl2 per kg of body weight, while the control animals received equal volume of sterile phosphate buffered saline. In this investigation individuals of both sexes aged 3, 6 and 12 month were used. Frequency of micronuclei formation was evaluated in polychromatic erythrocytes (PCEs), 24h hours after treatment. The results showed that that cadmium-cloride (CdCl2) exibits the genotoxic effects causing an increase of the frequency of micronuclei depending on concentration, sex, age and strain

Does inbreeding affects developmental stability in Drosophila subobscura populations?

In the present paper, we focused on the coadaptive aspect of genetic variability at population level and its relation to genomic stress such as inbreeding. The paper evaluates the effects of an experimental reduction of average heterozygosity after fourteen generations of systematic inbreeding in laboratory conditions, on developmental stability in Drosophila subobscura populations from two ecologically and topologically distinct habitats, knowing that they possess a certain degree of genetic differences due to their different evolutionary histories. The aims were to analyze: (i) the variability change of wing size (length and width) among the inbred lines from both populations; (ii) the relations between homozigosity and level of fluctuating asymmetry as a potential measure of developmental instability, in inbred lines originating from two populations. Results for the wing size showed similar between line variability pattern across generations of systematic inbreeding in both populations. The obtained results suggest that variability of fluctuating asymmetry as a measure of developmental instability can not be related to homozygosity due to inbreeding per se, in both experimental populations.Rad je fokusiran na ko adaptivni aspekt genetičke varijabilnosti na nivou populacije i u odnosu na genomski stres kao što je inbriding. Analizirani su efekti eksperimentalnog smanjenja prosečne heterozigotnosti nakon 14 generacija sistematskog inbridinga u laboratorijskim uslovima na razvojnu stabilnost Drosophila subobscura populacija sa dva ekološki i topološki odvojena staništa, znajući da one poseduju odredjeni stepen genetičke diferencijacije usled različitih evolutivnih istorija. Ciljevi rada su bili da se analizira: (i) varijabilnost u promeni veličine krila (dužine i širine) medju inbidingovanim linijama i populacijama; (ii) odnosi izmedju homozigotizacije i nivoua fluktuirajuće asimetrije kao potencijalne mere razvojne nestabilnosti u inbridingovanim linijama obe populacije. Rezultati veličine krila pokazuju sličnu varijabilnost medju linijama obe populacije kroz generacije inbridinga. Dobijeni rezultati sugerišu da varijabilnost fluktuirajuće asimetrije kao mere razvojne nestabilnosti ne mogu biti povezani sa homozigotizacijom usled inbridinga per se, u obe eksperimentalne populacije.Projekat ministarstva br. 17301

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