Northeast Bulgaria Research Articles

The Voynuks in the Military of the Ottoman Empire: Current State of Research and Pieces of New Evidence

During the conquest of the Balkan Peninsula by the Ottoman Empire in the fourteenth and fifteenth centuries, two castes of Christians emerged in the military of the empire—the spahis and the voynuks. The members of the first group, the spahis (noblemen in the feudal system), ceased to exist after the fifteenth century. On the contrary, the second caste, the voynuks, existed at least until the late nineteenth century and, thus, almost until the fall of the empire. The article discusses the role of the voynuks as members of the caste from Vardun—a small village in northeast Bulgaria nowadays but an important voynuk centre in the times of the Ottoman Empire. In the first part of the article, attention is drawn to the role of the voynuks in the state's military that accomplished a variety of military tasks. At the same time, the caste's members not only preserved their Christian religion but also paid fewer taxes than other Christians in the empire. The second part of the discussion focuses on why Vardun, in particular, gained such important voynuk status and kept it for several centuries. It is proposed that the Ottomans chose Vardun because of the origin of the people from the settlement; most probably, noblemen and warriors who defended the city of Kosovo (Mysionis) against the Ottoman army in the late fourteenth century and settled Vardun after Kosovo's destruction.

IGHV Mutational Status in a Cohort of Bulgarian CLL Patients: High Unmutated CLL Prevalence in North-East Bulgaria.

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. One of the best established CLL prognostic markers is the somatic hypermutational status of the IGHV gene which is a part of the immunoglobulin heavy chain variable region. Technology for IGHV genotyping has been optimized and has been applied in routine diagnostics for the first time in Bulgaria. A total of 105 patients with CLL from different Bulgarian regions were tested. IGHV mutational status was determined by Sanger sequencing on total genomic DNA (gDNA) or RNA extracted from mononuclear cells. All sequencing profiles were analyzed with the IMGT/V-QUEST tool. Within the course of the analysis a high percentage of IGHV unmutated status was established in the Varna district on the Black Sea (Northeast Bulgaria). In addition, the IGHV genotyping performed on gDNA revealed a rare case with multiple rearrangements. The present data from IGHV genotyping will help in choosing the proper treatment for the benefit of Bulgarian CLL patients.

A Novel Algorithm to Detect White Flowering Honey Trees in Mixed Forest Ecosystems Using UAV-Based RGB Imaging

Determining the productive potential of flowering vegetation is crucial in obtaining bee products. The application of a remote sensing approach of terrestrial objects can provide accurate information for the preparation of maps of the potential bee pasture in a given region. The study is aimed at the creation of a novel algorithm to identify and distinguish white flowering honey plants, such as black locust (Robinia pseudo-acacia) and to determine the areas occupied by this forest species in mixed forest ecosystems using UAV-based RGB imaging. In our study, to determine the plant cover of black locust in mixed forest ecosystems we used a DJI (Da-Jiang Innovations, Shenzhen, China) Phantom 4 Multispectral drone with 6 multispectral cameras with 1600 × 1300 image resolution. The monitoring was conducted in the May 2023 growing season in the village of Yuper, Northeast Bulgaria. The geographical location of the experimental region is 43°32′4.02″ N and 25°45′14.10″ E at an altitude of 223 m. The UAV was used to make RGB and multispectral images of the investigated forest massifs, which were thereafter analyzed with the software product QGIS 3.0. The spectral images of the observed plants were evaluated using the newly created criteria for distinguishing white from non-white colors. The results obtained for the scanned area showed that approximately 14–15% of the area is categorized as white-flowered trees, and the remaining 86–85%—as non-white-flowered. The comparison of the developed algorithm with the Enhanced Bloom Index (EBI) approach and with supervised Support Vector Machine (SVM) classification showed that the suggested criterion is easy to understand for users with little technical experience, very accurate in identifying white blooming trees, and reduces the number of false positives and false negatives. The proposed approach of detecting and mapping the areas occupied by white flowering honey plants, such as black locust (Robinia pseudo-acacia) in mixed forest ecosystems is of great importance for beekeepers in determining the productive potential of the region and choosing a place for an apiary.

Multi-local Actors of Change and Two Religious Sites in Northeast Bulgaria: Between Traditions and New Everyday Practices

The article analyses the correlations between the two rural religious sites – Akyazılı Baba Tekke (village of Obrochishte) and ‘St. Dimitar’ church (village of Gurkovo) in Northeast Bulgaria – and the multi-local actors of change that contribute to the transformation of local communities’ traditions and the emergence of new everyday practices. It is based on historical-ethnological research carried out in May 2022 that builds on earlier periodic observations.

Три непубликувани железни меча с езичеста дръжка от Северна България

The article discusses three unpublished iron grip-tongue swords found in North Bulgaria. Two of the artifacts have been recently obtained as stray finds, probably coming from disturbed graves in the area of Palamartsa Village, Popovo Region, in Northeast Bulgaria (Обр. 1.1 and 2.1; Карта 1.1). The third blade is kept at the National Museum of History in Sofia and allegedly originates from the region of Montana, Northwest Bulgaria (Обр. 2.10; Карта 1.2). Together with another twenty-five known items these weapons form the group of the earliest iron swords in ancient Thrace (Обр. 1 and 2; Карта 1). They are dated to the first phase of the Early Iron Age (1000–750 BC) and in tandem with the spears appeared to be the principal weapon, at least according to the grave goods (cf. Карта 3). The cut-and-thrust swords have clear prototypes in the local bronze tradition (Naue II type; cf. Карта 2) and they are one of the indicators of the early adoption of iron metallurgy in Thrace south of Lower Danube. The article systematizes the available information about the swords in terms of their origin, typology and chronology. On that basis the text attempts to reveal possible aspects of the fighting skills and warfare of the local ethne.

GIS-based model for the assessment of the smart sustainable development of municipalities of Northeast Bulgaria

In recent years, Bulgarian municipalities have introduced smart development systems. The Bulgarian state is at the top of the world rankings regarding household internet access and connection speed. The authors develop and validate a GIS-based model for the analysis and evaluation of sustainable cities. The authors conclude that in a global digital economy and society, Bulgarian regions need to improve the accessibility of WI-FI networks to meet the challenges of Smart Development. In recent years, the authors have observed a growth of Smart Cities initiatives in large areas of Northeast Bulgaria. However, Bulgarian municipalities in the study area are lagging in deploying smart governance systems.

The Application of The Uniform System of Accounts for The Lodging Industry in High- Category Seaside Hotels in Northeast Bulgaria

The Uniform System of Accounts for the Lodging Industry aims to provide an accounting model that can be easily adapted by hotels of different sizes and categories. The information from it should be useful for both internal and external users and allow the comparison of hotels located even in different countries. At this stage there is no thorough empirical study on the implementation of the Uniform System of Accounts for the Lodging Industry in Bulgaria. The present study investigates the implementation of the Uniform System of Accounts for the Lodging Industry in high- category seaside hotels in the Northeast region of Bulgaria.

Energy gains at daily periodic changes of the azimuths of PV modules in north-east Bulgaria

The higher efficiency of tracking photovoltaic systems is an indisputable fact and computational methods of the respective energy gains are well known. However the investments in the tracking systems are higher in comparison to the fixed ones due to the needs of additional equipment and automation systems. An options of periodical change of the azimuth of PV modules at single axis solar trackers and the correspondent incident solar energy are studied in this paper. An approach for numerical determination of the daily periods of cyclic rotations of the trackers and the subsequent electricity production is developed. It was applied to estimate the energy gains at such cyclic changes of a PV system in ceramic factory in Bulgaria.

Longitudinal recovery gradient of macroinvertebrates during different hydrological scenarios in a downstream river reach

Macroinvertebrate community composition in regulated rivers is highly dependent on high and low flow events. Significant reduction or augmentation of the flow downstream from a dam can lead to a decrease in the variety of the sensitive macrozoobenthic taxa. Such decreases may lead to a degraded ecological status. In this research, the macrozoobenthic community was investigated in a river section downstream of a multipurpose dam with strategic significance for northeast Bulgaria. Samples were collected for five years from the Golyama Kamchia River, in close proximity to the Ticha dam. Three sampling sites were established in a longitudinal gradient, from 75 to 1770 meters from the dam. Sixteen invertebrate samples were taken between 2017 and 2021. Double sampling (spring and autumn) was conducted in 2019. The goal was to find how macroinvertebrate communities are influenced by the dam-induced modified environmental conditions, from the management of the dam, and which of the parameters is considered to have the strongest effect. Likewise for the study was important to understand longitudinal recovery gradients from the application of the present “minimum acceptable flow – compensation flow” in hydrologically differing years. The main physicochemical parameters were measured alongside the velocity of the water at each sampling site. Additionally, the maintained hydrological regime was explored for a relationship by several hydrological indices with the macroinvertebrate community composition. The analysis of the biological data through 7 biological indices showed that hydrologically sensitive taxa (Ephemeroptera, Plecoptera and Trichoptera - EPT) were very good indicators for damming impact, detecting disturbances not so well differentiated by other type-specific indices and the resulting ecological status. The order Trichoptera was the most influenced taxa group during the study. In 2020 the base flow released from the dam dropped to its lowest level (0.095 m3 s-1 from 0.552 m3 s-1) for an explored 10-year period of hydrology. This event continued for more than a year and led to a rupture of the previously observed recovery gradient. Downstream of the second sampling site, at about 800 m below the dam wall, a decrease in the number of trichopteran families was observed and at the third site, at 1.8 km from the dam they were significantly reduced.

Disaster Risk Assessment of North Bulgarian Black Sea Coast

Abstract The methodology of comprehensive risk assessment for natural disasters has been the subject of recent research. The risk assessment process is thoroughly explained and applied to geological hazards (such as landslides, earthquakes, and tsunamis) that have a potential for calamity. Obtaining a complicated risk level for a few geophysical and geological risks in northeast Bulgaria is the major goal. It has been done to clearly identify the many dangers, their effects, the elements at risk, exposure, and vulnerability, as well as to analyze the secondary events that were generated. For the first time in practice, a thorough risk assessment approach is used, and it incorporates the idea of risk perception. The methodology’s adaptability enables the presentation of the results as either a risk matrix or a risk profile. It depends on the tasks, challenges, and scientific puzzles that need to be solved as well as expert judgment. The outcome showed strong practical applicability and sustainability.

Contribution to the Knowledge of Pontechium maculatum(Boraginaceae), a Species of High Conservation Concern in the Bulgarian Flora

Pontechium maculatum (Boraginaceae) is a species of high conservation concern in the Bulgarian flora. It is assigned a national IUCN category ‘Vulnerable’, legally protected according to the national Biological Diversity Act, and listed in Annex II of the Habitats Directive (Council Directive 92/43/EEC). Recent studies in one of the largest populations in the country revealed some new data about the species which are reported here. The population studied is situated in Mt Lozenska, Mt Sredna Gora (Western) floristic region. Relevant taxonomic literature states that P. maculatum is a biennial plant, however, our observations revealed the plants in Mt Lozenska are perennial (possibly short-lived). A great variation in the corolla-colour was observed, most plants having bluish to violet corolla and only a few – reddish to dark red. This can be explained by either natural variation in the population, not reported in the taxonomic literature so far, or by hybridisation with Echium vulgare which cooccurs in the same locality. Large fluctuation in the number of flowering plants in two consecutive years was recorded, with some 180 blooming specimens in 2019 and only about 25 in 2020. Studies in the genome size of this population revealed the plants have significantly higher DNA-content (1C-value) than plants from the typical populations of the species in Northeast Bulgaria floristic region, e.g. Kabiyushka Mogila locality. Further biosystematics studies(chromosome number, genome size, genetic studies, etc.) are currently in progress to explain the observed phenomena within the Bulgarian populations of P. maculatum.

Impact of the loess’ hydraulic characteristics on its degree of saturation for the purpose of radon index measurements (Northeast Bulgaria case study)

Radon gas has high mobility and is driven by advection and diffusion with the soil gas throughout connected and water-unsaturated pores and/or cracks in permeable rocks and soils. Therefore, there is a need for quantitative assessment of the saturation state, even on a daily-base in order to estimate the radon potential correctly. The more so as, the permeability is one of the key factors in the radon risk assessment. For the purpose of such investigation, a vertical profile model was elaborated for a study site in Northeast Bulgaria. On the base of pedotransfer function analyses, the hydraulic parameters describing the retention function and the hydraulic conductivity function were determined for each case study. The results show that even in a month with high amount of rainfall precipitation (13% of the total amount per year), the loess profile at certain depths remains unsaturated, regardless the difference in the hydraulic characteristics.

Interaction of the birch-bark terpenoids with human and bovine serum albumins

Abstract Interactions between pentacyclic triterpenes isolated from white birch (Betula pendula Roth.) bark samples from Northeast Bulgaria and bovine serum albumin or human serum albumin were investigated using fluorescence techniques. The experimental results show the formation of complexes between the isolated triterpenes with serum albumins. Quenching of the intrinsic fluorescence of human serum albumins was monitored by emission spectra of varied quencher concentration solutions. By analysing the fluorescence spectra and fluorescence intensity, some parameters of the serum albumins - quencher interaction were determined to evaluate the type of quenching. An extract containing the isolated triterpenes formed complexes with both bovine serum albumin and human serum albumin, leading to quenching the fluorescence of both albumins by a combined quenching mechanism.

Chemical Composition and Antimicrobial Activity of Essential Oil of Fruits from Vitex agnus-castus L., Growing in Two Regions in Bulgaria.

The chemical composition of Vitex agnus-castus L. (Verbenaceae family) fruits, collected from two regions in Bulgaria (south-central and north-east Bulgaria), was investigated. The content of proteins (5.3–7.4%), carbohydrates (73.9–78.8%), fiber (47.2–49.9%), ash (2.5–3.0%), essential oils (0.5%), and vegetable oil (3.8–5.0%) were identified in the fruits. The composition of the essential oils (EOs) of Vitex fruits from both regions was determined; the main compounds were 1,8-cineole (16.9–18.8%), α-pinene (7.2–16.6%), sabinene (6.7–14.5%), and bicyclogermacrene (7.3–9.0%), but significant differences in the quantitative and qualitative composition of EOs between the regions were found. The EOs of plants from north-east Bulgaria demonstrated antimicrobial activity against the pathogenic species Salmonella abony, Staphylococcus aureus, and Bacillus subtilis, but the Gram-negative bacteria Esсherichia coli and Pseudomonas aeruginosa exhibited resistance to the oil. Linoleic acid predominated in vegetable oil from both regions, followed by oleic acid. β-sitosterol and γ-tocopherol were the main components in the sterol and tocopherol fraction of the lipids. Phosphatidic acids were the main components in the vegetable oil from north-east Bulgaria, while in the vegetable oil from south-central Bulgaria, all phospholipids were found in almost the same quantity. Overall, significant differences were observed in the chemical composition (proteins, carbohydrates, ash and moisture) of the fruits from the two regions of Bulgaria, as well as in the content of the main components of their essential and vegetable oils.

Future Resilience of the Grain Farming System in North-East Bulgaria – Alternatives and Strategies for Adaptation

Grain farming is a well-established sub-sector in North-East Bulgaria that tenures most of the arable land in the region and contributes for substantial shares of the grain outputs of the country. This paper takes a system view of grain farming and examines how the farming system would change in response to perturbations. It employs participatory qualitative research methods to explore future alternative systems and possible strategies to achieve them. Envisaged future alternatives range from change of the farms through technological innovation and crop diversification to creating a new enterprise in processing or undertaking farming in a different region. They can be realised through predominantly self-reliant strategies while key relationships between actors in the farming system can be strengthened to ensure successful outcomes.

Validation and Optimisation of Common Clear Sky Models with a use case for North-East Bulgaria

One of the most significant error contributors to preliminary design tools for Photovoltaic power systems is related to the simple parametric Clear Sky models. Therefore, this paper focuses on providing a methodology and a more sophisticated open-source tool for 3 commonly used Clear Sky models. This includes all relevant steps involved in the process - from filtering the raw meteorological data, identification of Clear Sky regions, data redistribution to genetic optimization of selected model parameter, etc.use case is built upon a multiyear dataset obtained from TU Varna meteorological station between 2012-2016. A significantly higher density distribution of Clear sky segments was identified during the summer through the Clear Sky Identification algorithm. To avoid the risk of overfitting the models to purely summer months and poor model fits in winter months, which was found to be the case with the legacy model, the underrepresented clear sky regions (based on θ) were replicated until uniform distribution is attained. Subsequently, a genetic optimization was applied to selected parameters in the Clear Sky algorithms and the updated models showed a significant improvement in low winter months (θ) and even overall performance boost RMSE / MAE /R2. Furthermore, such validations and optimizations are recommended prior to any design or real-time PV-system analysis for the specific location.

Petrographic and geochemical analyses of flint raw materials from Bulgaria: A reliable combination for provenance studies of archaeological flint

The Bulgarian prehistoric sequence is characterized by the use of particular raw materials in distinct ‘cultural’ contexts. The Karanovo I and II stages of the Early Neolithic (part of a supra-regional technocomplex in the Balkans) are recognisable by formal toolkits made of Balkan flint. The Chalcolithic period is famous for its superblades made of high-quality Ludogorie flint, which also attain a wider Balkan distribution. Despite a solid corpus of reliable data for northern Bulgaria from our previous field surveys and laboratory analyses, there are still questions that can only be resolved by further research.This paper presents the results of petrographic and chemical (LA-ICP-MS) analyses of a series of archaeological artefacts and raw material samples collected during a survey in Shumen District of northeast Bulgaria. These data allow us to i) distinguish two new types of flint (Shumen I and II) which are represented by both raw material outcrops and artefacts and previously referred to as ‘Moesian flint’; and ii) expand our analytical data for the Kriva Reka type of Ludogorie flint, confirming its substantial role in prehistoric flint production, distribution and use. These results suggest a more complex network of raw material sources and distribution routes in prehistory than previously assumed.

Rescue Excavations of Bronze Age Barrows in Vetrino Region, northeast Bulgaria

Scopul acestui articol este prezentarea cercetărilor arheologice de salvare desfășurate în trei tumuli atribuiți epocii bronzului în regiunea Vetrino din nord-estul Bulgariei. În 2020 au fost cercetate în această regiune 14 morminte atribuite epocii timpurii a bronzului (mileniile IV– III î. Hr.), două epocii mijlocii a bronzului (prima jumătate a mileniului II î. Hr.) și unul atribuit epocii târzii a bronzului (a doua jumătate a mileniului II î. Hr.). Majoritatea mormintelor conțineau indivizi în poziția chircit pe o parte, atribuite perioadelor 3100– 2900 calBC și 2900– 2600 calBC. Sunt discutate tipul lor, caracteristicile și relația lor cu morminte contemporane din alte regiuni la nord și vest. Este pusă în discuție și datarea unor morminte cu indivizi în poziția chircit puternic în perioada 2000– 1500 calBC din nord-estul Bulgariei.

Citizen Science Assisted Monitoring Provides New Data Concerning the Distribution of the Bulgarian Bent-toed Gecko, Mediodactylus danilewskii (Gekkonidae, Squamata), in North-East Bulgaria

The Bulgarian Bent-toed Gecko (Mediodactylus danilewskii Strauch, 1887) is one of the two species of geckos inhabiting the territory of Bulgaria. In the recent years, new information on its distribution was published and big amount of data were collected. We organized an information platform for sharing data on the biology and live-range of M. danilewskii in inland North-East Bulgaria. This gecko is a highly synanthropic species which is often observed by citizens. Here we report on four new observation spots and also confirm the presence of the species from recently published localities. All data were recorded by volunteers, hence we discuss on the methods for documentation of the specimens and the critical role of the citizen science to assess the range of distribution of the species.

PRS33 Three YEARS Follow up of a Representative Cohort of COPD Patients in Bulgaria

At the end of 2015, 426 patients from Bulgaria were recruited by pneumologists across the country to participate in a prospective cohort study of Chronic Obstructive Pulmonary Disease (COPD) and were followed for 3 year period. Here we report data for patient status, pharmacotherapy changes, mortality, as well as costs. This is a prospective, multi-center, observational, randomized, representative, and comparative real-life study of previously diagnosed patients with COPD from 5 main regions - North-east Bulgaria [NEB], North-West Bulgaria [NWB], South-east Bulgaria [SEB]. South-west Bulgaria [SWB] including Sofia city. Patient characteristics, therapy costs and outcomes were analyzed and compared to results from 2016-2017. Statistics was done through MedCalc software version 14.8.1 At the end of year three, 406 patients remained in the study. Patients distribution according to severity of COPD are: GOLD A – 31 (7.38%); GOLD B – 145 (34.76%); GOLD C – 63 (15.24%); GOLD D – 161 (42.62%) for 2018, vs 30,149,65, and 182 in 2015, respectively. 22 patients had died, with 20 of them being in GOLD D. Median age was 66 years (65-68 years 95%CI) with 132 patients (31.36%) experiencing a change to pharmacotherapy compared to previous years, with 35 recorded instances of improvement and 44 instances of worsening of COPD symptoms. Average number of exacerbations was 2.10 (1.94-2.27 95%CI) with no significant change. Median monthly costs of pharmacotherapy were: 59.63 BGN paid by the NHIF (43.41-59.63 96%CI) and 13.08 per patient as co-pay. The cost of group C decreased due to deceased patients, cost in group A and B remain constant, and cost in group C increased. The main cost driver appears to be the severity and mortality of patients with insignificant changes in other health care resources used and significant changes in pharmacotherapy.