Northeastern Bulgaria Research Articles

Pollen-based paleoclimate reconstructions of Beloslav Lake (Northeastern Bulgaria) during the last 6000 years using modern analog technique (MAT)

The aim of the present study is to reconstruct the palaeoclimate variables in the Beloslav Lake Region (Northeastern Bulgaria) during the last 6000 years, based on the pollen analysis from lacustrine core Bel-1 and using modern analog technique (MAT). Pollen data was used for reconstructions of four parameters: average annual temperature, average temperature of the warm and cold half-year and average annual precipitation.

What contingency reward indicates – evidence from Bulgaria

Abstract Systems diagrams allow one to model the way in which complex systems work. They support thinking through the way in which the factors within a system interact and feedback upon themselves. Leadership, followers’ engagement and performance are depicted via Systems diagram approach. Current survey examines leadership behaviour toward followers, i.e. transformational and transactional styles. Full Range Leadership Model is employed to explore leader behavior with respect to Contingency reward. Objective of the paper is to examine Contingency reward within a framework of two surveys. The first one is conducted in 2017 in leading manufacturers in the light industry located in Northeastern Bulgaria. The second study was conducted in 2015 in public administrations located in the North central and Northeastern region in Bulgaria. Respondents in both are first line managers. Average values and validity analysis are performed. As a result, Contingency reward is consistent with transformational leadership.

Plant biodiversity hotspots mapping and prioritization in the Bulgarian floristic region Eastern Balkan Mountains

The main goal of the present study was to create a dynamic map of plant biodiversity hotspots of the Bulgarian floristic region Eastern Balkan Mountains. A GIS model, as well as a weighted value scheme for scoring each area, were created in order to identify and to prioritize the hotspots. A total number of defined hot spots of phytodiversity was 34. They were categorized into five classes, based on the cumulative weighted value scheme, and were indicated on the map using color scale. The territories into category I predominated, contrary to preceding investigations of the Black Sea coast and northeastern Bulgaria where category V predominated. In addition, an attempt to refine the borders of the floristic region was made.

Postmenopausal bone health may be influenced by the presence of arterial hypertension and antihypertensive therapy

Introduction: Despite available evidence for a link between bone health and arterial hypertension (AH), the results of clinical trials remain conflicting. Thus, we conducted a cross-sectional study to analyze a possible association between blood pressure (BP), antihypertensive therapy and deteriorating bone health in postmenopausal women. Materials and Methods: The study included 84 women from Northeastern Bulgaria. Their mean age was 60.54 ± 7.07 years, and their mean duration of menopause was 11.45 ± 6.62 years. Bone health was assessed by dual-energy X-ray absorptiometry (DEXA) and by analysis of bone metabolic markers. Results: A significant negative correlation was established between bone mineral density (BMD) and diastolic BP. On the other hand, AH predominated in the studied population. However, among the subjects diagnosed with osteopenia and osteoporosis, a significantly higher proportion of AH was observed. In addition, differences were found according to the stage of AH and according to the intake of antihypertensive therapy, when assessing BMD and fracture risk. In subjects with newly diagnosed and respectively untreated AH as well as in the group of stage III AH, the lowest BMD and the highest fracture risk were found. Although we reported a significant difference in the mean age of women according to the presence of AH and its stages, after further analysis it was found that the presence of AH is an independent risk factor for bone health in postmenopausal women (OR = 2.14 (0.686–6.703); p = 0.015). Conclusion: According to the obtained results, we assumed that AH was risk factor for bone health in postmenopausal women, as it was associated with lower BMD and higher fracture risk. In addition, we found differences according to the stage of AH and antihypertensive therapy, which might be considered in the prevention, prophylaxis and treatment of osteoporosis.

Detailed GIS mapping of communities of plants with conservation status and defining the touristic zones in the group "Kanarata and Quarry Drenaka" of the protected area "Pobiti Kamani" (Northeastern Bulgaria)

Detailed GIS mapping of communities of plants with conservation status and defining the touristic zones in the group "Kanarata and Quarry Drenaka" of the protected area "Pobiti Kamani" (Northeastern Bulgaria)

Detailed GIS mapping of communities of plants with conservation status and defining the touristic zones in the group "Kanarata and Quarry Drenaka" of the protected area "Pobiti Kamani" (Northeastern Bulgaria)

The aims of the present study were: 1) to perform a detailed mapping of the distribution of conservationally significant (endemic, vulnerable, endangered and protected) plant species in the group "Kanarata and Quarry Drenaka" of the protected area "Pobiti Kamani" for 2020 yr in GIS environment; 2) based on the overlap of the distribution sites of plant species, to determine the "hot spots" of plant biodiversity, access to which should be limited in order to protect them and at the same time to identify areas with no or low concentration of conservationally important species in order to trace and mark the tourist paths in the protected area. In order to investigate the distribution of six plant communities, a detailed GIS mapping was performed. As a result of the study, detailed distribution maps of investigated species communities in Central Group were drawn. Special attention is paid to the zones where two or more communities were overlapped. The identification of the areas with concentration of conservation-significant species and localization of "hot spots" is crucial for protection management of the group "Kanarata and Quarry Drenaka" of the protected area "Pobiti Kamani". The model of "hot spots" and the model of overlapping are applicable and in combination with detailed distribution maps are fundamental for more successful protection and conservation. The suggested touristic zones with lack of conservation species can be used to trace and to construct environmentally friendly tourist trail and paths without destroying and harming the species, their habitats, and the aesthetic and recreational value of the landscapes.

Attitudes Of Midwives From Northeastern Bulgaria For Discovering Independent Obstetrics Practices

In recent years we have witnessed many organized conferences and meetings where health professionals try to offer improvements in the quality of health services.\ \ The information vacuum in which young mothers find themselves after birth requires the organization of paid courses by private individuals to meet this natural need. Many non-governmental organizations and associations have been established with the main mission - imposing a mandatory standard and protocols for good medical practice and health care. The aim of the present study is to establish the attitudes and readiness of midwives from northeastern Bulgaria to open independent obstetric practices. A sociological method was used, as 94 midwives from the Maternity Wards and the wards / sectors of Pathology of Pregnancy in regional cities of northeastern Bulgaria were interviewed individually and anonymously. Documentary method, analyzing literature sources examining the subject of the present study. Statistical method used in the analysis of the results of our own research. Midwives from northeastern Bulgaria, working in maternity wards, almost categorically (95%) answered that there is currently a need to optimize obstetric care after childbirth. They answer the question of introducing patronage obstetric care even more categorically - 98% support this idea. Significantly high percentage - 86% of respondents are willing to provide obstetric care in the mother's home. Almost half of the surveyed midwives - 47% answered that they need additional training to perform home care. Conclusions: 1. Midwives want the restoration of patronage obstetric care. 2. Midwives are willing to perform such activities. 3. Midwives want to get involved in independent obstetric practices.

DEMOGRAPHIC CHARACTERISTICS OF THE SEROPREVALENCE OF HUMAN TOXOCARIASIS AMONG THE POPULATION OF NORTH-EASTERN BULGARIA

Toxocariasis is a tissue zoonosis caused by Toxocara spp. and the exposure to these geohelminths varies in different parts of the population in a particular region. The purpose of the study is to reveal the seroprevalence of toxocariasis in North-eastern Bulgaria and to establish its demographic structure. Material/Methods: Within the scope of a broad seroepidemiological study, 701 individuals from North-eastern Bulgaria were tested for anti-Toxocara antibodies (ELISA) between 2017 and 2020. The results were stratified and analysed by age, gender, and place of residence. Results: The overall seroprevalence of human toxocariasis in North-eastern Bulgaria is 18.54%. Children (18.85%) and adults (18.30%) show similar levels of infection, but the stratified analysis by age in 5-years intervals revealed notable discrepancies. In younger children, the seroprevalence is higher than the observed for the entire population (0-4 years - 22.22%; 5-9 years - 22.22%), while in adolescents and adults is lower than average. In the elderly, the seroprevalence rises to its highest levels (60-64 years - 30.56% and over 65 years -31.67%). Although there are variations between males and females, gender is not a significant factor for the distribution of toxocariasis. Higher seroprevalence levels in residents of the smaller settlements of the region (children - 28.18%; adults -29.10%) correspond to a 2.5-fold increase in the odds of contracting toxocariasis in comparison to the ones living in Varna city. Conclusion: The overall seroprevalence of toxocariasis in North-eastern Bulgaria is alarmingly higher than the levels reported from other parts of the country, placing this unknown infection in a leading position among the parasitic zoonoses. The place of residence is the most significant factor driving the uneven distribution of the disease.

HIGH SEROPREVALENCE FOR TOXOCARIASIS AMONG MINORITY GROUPS OF VARNA REGION, BULGARIA

Toxocariasis in humans is a little-studied zoonosis, and there are no data on the impact of this parasitosis on the minority groups in our country. The purpose of this study is to establish the seroprevalence of toxocariasis among ethnic groups in the Varna region, North-eastern Bulgaria, and compare the results with a control group from the general population. Material/Methods: As a part of a large seroepidemiologic study, we assessed the presence of Toxocara IgG among 132 individuals, self-identified with Turkish and Roma ethnicities. As a control group, we used 250 sera from children and adults from a control group. The statistical comparison was performed regarding age, sex, and type of residence. Results: Toxocara IgG were established in 43 individuals from the minority groups (seroprevalence of 32.58%) and 39 persons in the control group (15.60%) with а statistically significant difference (odds ratio = 2.61). Considerably high seropositivity in the investigated ethnicities was discovered after separating by age: children-33.33%; adults-32.00% and gender: male-38.98%; female-27.40%. A detailed analysis revealed that the type of settlement is an important confounding factor. The seropositivity among the minority ethnic groups residing in small towns and villages is 35,40%, in contrast to the residents of Varna city of the same ethnical origin (15.79%); OR = 2.92. Conclusion: The established high seroprevalence for Toxocara IgG among minority ethnic groups, especially those residing in the rural settlements of North-eastern Bulgaria, shows undiscovered to this point increased risk for the spread of toxocariasis among this population.

Spatial Structure and Chronological Development of the Prehistoric Salt-production Complex of Provadia-Solnitsata

The prehistoric complex of Provadia-Solnitsata is located close to the modern-day town of Provadia in Northeastern Bulgaria. The remains represent the oldest salt-production site in Europe (5600 – 4350 BC) from which emerged the earliest prehistoric urban settlement on the continent (4700 – 4350 BC). The complex occupies an area of approximately 30 hectares. The emergence and development of the site were closely related to the largest and in fact the only rocksalt deposit in the Eastern Balkans, the so-called Mirovo salt deposit on which the settlement sits. Salt production on the site was based on the brine (thick saline water) that flowed out of this salt deposit. Brine boiling in ceramic pots at Provadia-Solnitsata is the earliest example on record in Europe for the use of this technology in salt production. It was practiced on this site for longer than one millennium. The heat needed for the process was generated in advance in a special installation or alternatively, was directly provided by an open fire, in both cases by burning firewood. At the end of the Chalcolithic, a change of technology had to be introduced – the water from the brine was then evaporated in a large ‘basin’ by using heat from solar radiation. The development of the five parts of the complex is presented: the tell with deposits from the Late Neolithic and the Chalcolithic, a cemetery from the Early Bronze Age, a Thracian ‘ruler’s residence’ from the 2nd – 1st centuries BC and a very large tumulus on top; a salt-production center from the Late Neolithic and the Chalcolithic together with ritual facilities from that time; a Late Neolithic pit sanctuary and a cemetery from the Middle Chalcolithic over it; a pit sanctuary from the Late Chalcolithic; a cemetery from the Late Chalcolithic.

Some Bivalvia of the Topola Formation (middle Sarmatian), Northeastern Bulgaria

The fossil bivalvian fauna established in the Topola Formation, the Zelenka section, Northeastern Bulgaria was studied. Six taxa from the species group are described: Obsoletiforma cf. pseudosemisulcata (Andrussov, 1902), Obsoletiforma cf. balcicense (Gillet, 1938), Obsoletiforma cf. centopleura (Andrussov, 1902), Obsoletiforma sp. (aff. obsoleta Eichwald, 1830), Obsoletiforma sp. (aff. lucinoidea Paramonova, 1977), and Inaequicostata sp. (aff. barboti R. Hoernes, 1874). Two of them – O. сentopleura, and O. lucinoidea are announced for the first time in Bulgaria. One taxon is determined at generic level – Obsoletiforma sp. The stratigraphic position of the section in the upper part of the middle (Bessarabian) substage of the Sarmatian (s.l.) stage was determined as the upper part of the interval zone Cryptomactra pseudotellina-Cryptomactra pesanseris and/or lowerest part of the local taxon-range zone Obsoletiforma balcicense. The factors of the abiotic environments and their influence on the presence of the bivalvian fauna in the section are clarified.

The emergence and evolution of Neolithic cattle farming in southeastern Europe: New zooarchaeological and stable isotope data from Džuljunica-Smărdeš, in northeastern Bulgaria (ca. 6200–5500 cal. BCE)

Cattle were of great importance for the Neolithic farmers of southeastern Europe, in particular as farming expanded towards the well-watered regions of Džuljunica (ca. 6200–5500 cal. BCE), one of the earliest known Neolithic settlements in northeastern Bulgaria. The clear stratigraphy and the substantial Bos assemblage from Džuljunica Provided us with a great opportunity to investigate the beginning and evolution of cattle husbandry in the northern Balkans through stable isotope and zooarchaeological analyses. The relative abundance of Bos at Džuljunica leaves no doubt about the importance of beef and cattle herding. Mortality profiles suggest a transition in the early phases of the Neolithic from beef-oriented to mixed beef and milk production husbandry, enabled through intensified post-lactation culling. Stable carbon and oxygen isotope analysis of tooth enamel on a limited number of samples provides no evidence for an extended calving season for increasing milk availability or for vertical mobility. Stable carbon and nitrogen isotope values of bone collagen suggest that cattle were kept near the site, where C3 and C4 plants were available in summer, and that they were occasionally foddered with forest resources in the winter. Cattle experience a diachronic reduction in size on a regional scale, possibly due to farmers' choices aimed at more manageable herds consisting of smaller individuals. Restricting intermixing with local aurochs and the arrival of a new type of cattle may also have contributed to this change. Local factors or inter-regional influences may have influenced the ways cattle husbandry evolved at Džuljunica in particular and in northeastern Bulgaria more generally. More data from the region are necessary to flesh out the role of the interplay among environmental factors, local developments, and inter-regional contacts that facilitate the transfer of skills and traditions relating to the changing modes of cattle husbandry.

An analysis of the potential use of waste materials for biogas plant development

Various industrial waste materials have great potential, especially as a substance for biogas production. The aim of the present study is to analyse the possibility of using the waste materials extracted in Northeastern Bulgaria for biogas plant development. The study indicated that the most common waste materials in Northeastern Bulgaria are in the following ratios Agricultural waste - 44%; Livestock breeding waste - 34%, Waste water - 20% and Seaweed - 2%. Individual samples of the waste materials thus grouped were also examined and biogas was produced from them, after which the density and the lower heating value (LHV) were studied. The analysis of the results showed that the highest LHV are associated with Forage waste - 27.11 MJ/kg, and the lowest one relates to Brown algae - 11.06 MJ/kg, and the density indicates the opposite tendency, with the highest figures related to Brown algae - 1.363 kg/m3, and the lowest values - to Forage waste - 0.994 kg/m3. According to the analysis, the most efficient raw material for biogas production in Northeastern Bulgaria is Forage waste, which is due to its heterogeneous content. In conclusion, Northeastern Bulgaria can be claimed to have various waste materials which are a prerequisite for establishing a biogas production plant.

Some Bivalvia of the Topola Formation (middle Sarmatian), Northeastern Bulgaria

The fossil bivalvian fauna established in the Topola Formation, the Zelenka section, Northeastern Bulgaria was studied. Six taxa from the species group are described: Obsoletiforma cf. pseudosemisulcata (Andrussov, 1902), Obsoletiforma cf. balcicense (Gillet, 1938), Obsoletiforma cf. centopleura (Andrussov, 1902), Obsoletiforma sp. (aff. obsoleta Eichwald, 1830), Obsoletiforma sp. (aff. lucinoidea Paramonova, 1977), and Inaequicostata sp. (aff. barboti R. Hoernes, 1874). Two of them – O. сentopleura, and O. lucinoidea are announced for the first time in Bulgaria. One taxon is determined at generic level – Obsoletiforma sp. The stratigraphic position of the section in the upper part of the middle (Bessarabian) substage of the Sarmatian (s.l.) stage was determined as the upper part of the interval zone Cryptomactra pseudotellina-Cryptomactra pesanseris and/or lowerest part of the local taxon-range zone Obsoletiforma balcicense. The factors of the abiotic environments and their influence on the presence of the bivalvian fauna in the section are clarified.

SUCCESSFUL DEVELOPMENT OF RURAL AREAS IN NORTHEASTERN BULGARIA BY CREATING AND IMPLEMENTING A SOFTWARE PRODUCT FOR MILK AND DAIRY PRODUCERS

A large portion of the territory of Bulgaria, more than 80%, falls within the so-called rural areas. The situation is similar with the European Union, with more than 85% of its territory falling within these specific areas, whereas rural areas in the United States of America encompass more than 90% of the territory of the states. Naturally certain nuance differences exist in the definitions that different countries in the world use to define an area as a rural area and this report reviews these specifics. A portion of these particular activities are related to the development of livestock breeding and the production of milk and dairy derivatives. The purpose of this report is to encompass and analyze the advantages of the creation, the implementation and approbation of software product in the production and processing of milk and dairy products in Northeastern Bulgaria. Several main conclusions have been made in the scientific report, with the general conclusion being that on the basis of the computer program developed and implemented in practice, an easier method of work is ensured, while taking into account the specific pre-production and production processes, as well as processing operations in the area of dairy production and the creation of complete dairy products with added value.

Population genetic structure and diversity of the East Balkan Swine (Sus scrofa) in Bulgaria, revealed by mitochondrial DNA and microsatellite analyses.

The East Balkan Swine (EBS) is the only indigenous pig breed in Bulgaria. We analyzed the mitochondrial DNA (mtDNA) control region and 21 microsatellite loci for 198 individuals from 11 farms in Bulgaria. Obtained 11 mtDNA haplotypes including three novel ones were grouped to two major clades, European clade E1 (146/198 individuals, 73.7%) and Asian clade A (52/198, 26.3%). The mixture of the two clades may have resulted from historical crossbreeding between the European and Asian pig breeds. Clade A was frequent in southeastern Bulgaria (Burgas Province), but less frequent or absent in northeastern Bulgaria (Varna and Shumen Provinces). The distribution of Europe- and Asia-specific haplotypes relative to EBS farm locations could be attributed to regional differences of breeding systems (e.g., crossbreeding with imported commercial pigs). A microsatellite analysis showed high heterozygosities for all the EBS farms, and negative inbreeding coefficients presumably due to crossing with commercial pigs or wild boars and/or efforts to reduce inbreeding by farmers. Bayesian clustering analyses showed that all farm populations are genetically well distinguishable from one another. Although diversity has been maintained by the efforts of farmers and a breeding association, the effective population size remains small, and conservation efforts should be continued.

Study of regime parameters of the fermenter in the production of biogas from animal liquid waste materials

The focus of the present study is a small biogas power plant for anaerobic fermentation of several types of animal waste raw materials used for biogas production. The impact of some of the characteristics of substances such as composition, temperature, humidity, and pH of the mixture in the bioreactor has been considered. The above is vital for optimizing the fermentation process, and also to improve the biogas production process. The plant is located in Northeastern Bulgaria and the raw liquid manure is supplied by several neighboring small farms. The annual quantities of raw waste are as follows: cow manure - 1252 t / a; chicken manure - 427 t / a and pig manure - 639 t / a. The manure is collected in a preliminary tank and then pumped to the bioreactor. The fermenter itself is a hermetically sealed and thermally insulated tank where constant temperature is maintained. It is equipped with a stirring system, which helps the mixing and homogenization of the substrate. The tests were performed during three charges of the installation. The fermentation takes approximately 23 up to 25 days. The experiments were performed during the summer and autumn seasons when the ambient air temperature varies from 28 to 45 °C. The biogas can be used as an energy carried as the obtained organic fertilizer is suitable for agriculture purposes.

Genetic diversity and population structure of bread wheat varieties grown in Bulgaria based on microsatellite and phenotypic analyses

Determining the genetic diversity and population structure of the modern hexaploid wheat varieties currently grown in Bulgaria is fundamental for selection of genotypes with desirable traits resilient under climatic fluctuations and development of successful crop improvement programmes. In this study, simple sequence repeat (SSR) markers were used to characterize a population of 117 modern wheat varieties (Triticum aestivum L.) from Bulgaria and several Western, Central and Eastern European countries. The genetic diversity was higher in the Western and Central European varieties than in the Bulgarian and the remaining Eastern European ones. Model-based population structure analysis defined 2 sub-populations (K = 2) dividing the Central and Western European varieties from the Bulgarian ones. Subsequent genetic structure analysis at K = 3 revealed an additional separation of the Bulgarian varieties in two distinct sub-populations. The phenotypic diversity among the varieties was evaluated in the fields of Dobrudzha Agricultural Institute, G. Toshevo in North-Eastern Bulgaria for three consecutive years. The distribution of the varieties in the biplot analysis in terms of grain yield and its components revealed differences in their adaptation to the agro-climatic conditions of North Bulgaria according to their geographical origin. These results and the prevalence of specific SSR alleles in the sub-populations suggest distinct adaptive mechanisms to specific agro-ecological regions. The data will be of interest for both breeders and farmers and could serve as a basis for wheat improvement programmes and further association mapping for important agronomic traits expressed under different environmental conditions. Supplemental data for this article is available online at https://doi.org/10.1080/13102818.2021.1996274 .

Vegetation in Bulgaria according to data from satellite observations and NASA models

Introduction. The condition of the vegetation cover can be traced from Space. Aim of the research. To assess the condition of the vegetation cover in Bulgaria during the last twenty years – its distribution over the country, its change in connection with the typical climatic changes, its seasonal change. Material and methods. The vegetation index NDVI according to NASA data was used to analyze the condition of the vegetation cover in Bulgaria for the years 2000-2020. The methods used were: seasonal data decomposition, t-test, GIS methods for spatial representation of data, Fourier analysis. Conclusions. 1. During the summer months the vegetation in the eastern parts of the territory of Bulgaria is noticeably weaker than in the western parts. The influencing factors-drought and frequent fires are probably related to global warming. 2. For the territory of Bulgaria there is a seasonal rotation of the horizontal gradient of the vegetation index in a counterclockwise direction-from east to west in summer, from northeast to southwest in autumn and from north to south in winter. 3. There is a winter increase in vegetation for Northern Bulgaria and to the greatest extent for Northeastern Bulgaria, as well as for Southwestern Bulgaria. Together with the decreasing snow cover, the winter vegetation contributes to the drought in the eastern parts of the country.

STUDY ON THE FREQUENCY OF TEETH BRUSHING FOR PATIENTS WITH TERMINAL STAGE OF CHRONIC KIDNEY DISEASE AND BEING ON CHRONIODIALYSIS, AND HEALTHY CONTROLS

Dentists usually recommend at least two minutes of brushing two times per day as a minimum. The purpose of this study is to establish the frequency of teeth brushing for patients with terminal stage of chronic kidney disease and for healthy controls. Materials and methods: 140 patients from Northeastern Bulgaria took informed participation, volunteering, in this study. They are separated into two groups – 70 people were diagnosed with terminal stage of chronic kidney disease (CKD) and chroniohemodialysis at different stages of disease duration and 70 healthy controls. Anamnestic and socio-demographic data were collected, about gender, age and frequency of teeth brushing. The result was statistically processed using the IBM SPSS Statistics software, Version 20. Results: Data show that there is a statistically significant difference (χ2 = 79,031, p=0,000 ) between the patients of the groups studied. As we have expected, the patients from the control group brush their teeth more often (between 2 and 3 times per day). The Mann-Whitney test with Bonferroni correction shows that the CKD patients brush their teeth daily less than the people from the control group. Statistically significant difference (U = 1831,000, р = 0,004) is established between the two group participants. Conclusion: The frequency of teeth brushing as a main factor for maintaining good personal oral hygiene is higher for the healthy controls in comparison to the patients under the study, who belong to the group of people with CKD. We need more studies in order to understand better how could the frequency of teeth brushing influence the limitation of oral problems for people with kidney diseases on chroniodialysis.