Search Results (22)

Efficient and fair allocation of donated blood depends on multiple factors, like medical urgency, donor/recipient compatibility, blood availability, geographic location, limited shelf life, etc. Due to the limited supply of blood and its critical role in healthcare, fair distribution protocols are essential. This study builds upon previous authors’ research that proposed a general mathematical model for fair blood allocation, taking as inputs the universal blood compatibility chart and the assumption of allocating equal shares of the donated blood from each blood type to recipients with respectively compatible blood types. The sum normalization technique was performed (twice, first per recipients and then per donors) for the purpose of balancing between donation needs and options. The result was an indicative blood allocation reference framework in support of the decision making in transfusion haematology. In the present paper, we tailor that general model by introducing as model variables the actual blood group frequencies of a given population. Additional customization is proposed by adding weight coefficients to the values along the framework’s main diagonal that represent ABO-identical transfusions, preferred to non-identical transfusions for minimizing the risks of hemolytic reactions. The model is further elaborated via intervalization of the estimations in the resultant blood allocation framework, thus making the model more flexible and usable. While demonstrated with Bulgarian blood group distributions from 2023, the model can be adapted to other populations and contexts. Full article

This study examines the qualities and potential uses of various types of biomass as fuel, focusing on wood pellets, sunflower husk pellets and mixed pellets. The primary objective is to analyze the thermal and energy properties of these pellets in order to evaluate their efficiency and acceptance by consumers in the Bulgarian market. Thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) are employed, revealing that the processes of drying and volatile substance release are accompanied by energy absorption, with combustion being the main stage where most heat is generated. The results show that wood pellets have 7.31% moisture, 0.72% ash and a calorific value of 18.33 kJ/kg; sunflower husk pellets have 7.62% moisture, 2.42% ash and a calorific value of 19.63 kJ/kg; and mixed pellets have 7.07% moisture, 0.69% ash and a calorific value of 18.05 kJ/kg. These findings indicate that the pellets achieve efficient combustion with minimal mass loss. The conducted marketing research reveals that Bulgarian consumers prefer wood and mixed pellets for their efficiency, although sunflower husk pellets are more affordable. Key factors influencing consumer choice include price, which is important for 51% of the respondents, and quality, prioritized by 34%. The conclusion of this study is that pellets are a promising energy source with good environmental and economic characteristics, and the results can contribute to the development of more efficient fuels adapted to the needs of the market and consumers. Full article

To face climate change, searching for alternative crops resistant to drought and heat stress becomes necessary, along with efficient germplasm management. Old landraces well-adapted to local climatic conditions, pests, and pathogens could be used as a source of desired traits. Cowpea (Vigna unguiculata L. Walp.), grown mainly in the tropical and subtropical areas, presents superior drought and heat stress adaptation compared to other legumes. Limited information is available on field performance and nutrient qualities of cowpea landraces originating from southern Bulgaria. The aim of the present study was to compare in field conditions and their impacts on plant performance, yield, and the seed biochemical composition of Bulgarian cowpea accessions, including fourteen landraces and one variety. Higher-yielding, earlier-maturing accessions were discerned. Among the landraces studied, B1E0103 was the most productive under the agro-climatic conditions in Sadovo, central Bulgaria; BOE0035 had the earliest maturity. The seed moisture content was 11.5 ± 0.3%, and the energy value was 347.9 ± 1.2 kcal/100 g. The crude protein content varied from 22.5 to 27%, the lipids were 1.6–2.55%, the carbohydrates were 56.5–61.4%, ash was 3.8–4.3%, dietary fibers were 3.1–4.5%, tannins were 16–22%, phenols were 1.3–4.4 mg/g, flavonoids were 1.85–3.7 mg/g, and the trypsin-inhibiting activity was 0.7–2.5 units/mg FW, with the lowest in BOE0010, the variety “Hrisi”, and B1E0103 and the highest in B0E0035, A9E1230, and A8E0562. Landraces are promising genetic material for future research and breeding purposes. Full article

In this study, we aimed to assess the activity of the essential oils from four Bulgarian oil-bearing roses Rosa damascena Mill., R. alba L., R. centifolia L., and R. gallica L., on the reference strain Mycobacterium tuberculosis H37Rv and clinical M. tuberculosis strains of the Beijing and Latin-American Mediterraneum genotypes. The chemical composition of the essential oils was determined by gas chromatography (GC-FID/MS). Minimal inhibitory concentrations (MIC) were determined using the resazurin method. R. alba oil showed the highest inhibitory activity when tested on all strains of different phylogenetic origins with MIC in the range of 0.16–0.31 mg/mL, while R. gallica oil was the least active (MIC 0.62–1.25 mg/mL). The obtained results show heterogeneity of rose oil action on different mycobacterial strains and we hypothesize that the combined level of geraniol and nerol is a key factor that underlies the antimycobacterial action of the rose oils. Strain Beijing 396 was relatively more susceptible to the rose oils probably due to multiple and likely deleterious mutations in its efflux pump genes. Two clinical MDR strains have likely developed during their previous adaptation to anti-TB drugs certain drug tolerance mechanisms that also permitted them to demonstrate intrinsic tolerance to the essential oils. Further research should investigate a possible synergistic action of the new-generation anti-TB drugs and the most promising rose oil extracts on the large panel of different strains. Full article

Durum wheat is mainly used for products for human consumption, the quality of which depends on the content of protein and yellow pigments in the semolina. The challenges faced by modern breeding, related to population growth and climate change, imply improvement of both grain yields and quality in durum wheat germplasm well adapted to specific agro-climatic conditions. To address those challenges, a better understanding of the genetic architecture of agronomic and quality traits is needed. In the current study we used the Genome-Wide Association Study (GWAS) approach in a panel of Bulgarian and foreign genotypes to define loci controlling agronomic and quality traits in durum wheat. We mapped 26 marker traits associations (MTAs) for four of the six studied traits—grain yield, grain protein content, seed yellow colour (CIELAB b*), and plant height. The greatest number of MTAs was detected for grain yield. Seven MTAs were detected for each grain protein content and seed colour, and one MTA for plant height. Most of the reported associations had confidence intervals overlapping with already reported quantitative trait loci (QTLs). Two loci controlling grain yield were not reported previously. The MTAs reported here may be a valuable tool in future breeding for improvement of both grain yield and quality in durum wheat. Full article

The presented work provides a comprehensive evaluation of the current availability of education programs and courses related to of AI the field of Information Technologies and Computer Science in higher education institutions (HIEs) in the Republic of Bulgaria. More specifically, this study examines 163 bachelor’s and 239 master’s degree programs from 28 HEIs available during the 2023/24 academic year in four professional fields: (1) Electrical Engineering, Electronics, and Automation; (2) Communication and Computer Technologies; (3) Informatics and Computer Science; and (4) Mathematics. The conducted evaluation shows that 41.1% of evaluated BSc programs and 26.4% of MSc programs include at least one AI-dedicated course. Results indicate a significant presence of AI-focused education, particularly in degrees related to Informatics and Computer Science, where 47.8% of AI courses are concentrated. However, a notable disparity exists in the inclusion of AI subjects across other technical fields, particularly in Electrical Engineering and related degrees, which contain only 8% of the identified AI courses for BSc degree programs. The findings highlight the need for a broader and more accelerated integration of AI education to meet the evolving demands of both students and the labor market. This work underscores the importance of strategic curriculum adaptation to enhance the readiness of Bulgarian HEIs to support the development and application of AI technologies, addressing the skills gap and fostering a workforce capable of navigating the AI-driven future. Full article

This paper presents the first data on the biodiversity of lithophytic algae from Bulgarian megaliths obtained after the application of the direct sampling method, subsequent cultivation, and processing by light microscopy. A rich algal flora was found: 90 species and 1 variety of 65 genera from Cyanoprokaryota/Cyanobacteria (29 species, 13 genera), Chlorophyta (40 species and 1 variety, 38 genera), Streptophyta (5 species, 1 genus), and Ochrophyta (16 species, 13 genera). Among them were the globally rare Pseudodictyochloris multinucleata (Chlorophyta), found for the first time in such lowland and warm habitats, and Scotiella tuberculata (Chlorophyta), for which this is the first finding in the country. Three of the recorded species are conservationally important. The low floristic similarity between the sites (0–33%) shows the diversity of the algal flora, with no common species found for all the megaliths studied. The most widespread were the strongly adaptive and competitive Stichococcus bacillaris, Apatococcus lobatus, and Chloroidium ellipsoidium (Chlorophyta). The correlations estimated between the species number and substrate temperature (18.1–49.6 °C) suggest the prospect of future research related to the impact of global warming. In addition, the study points to the safety aspects as it revealed species from nine potentially toxin-producing cyanoprokaryotic genera that could be harmful to visitors’ health. Full article

The aims of this paper are to present the methodology, derived mathematical expressions for determining the individual factor influences and the adaptation for the conditions of dynamic deterministic factor analysis and the results of the application of the developed new method for deterministic factor analysis, called the averaged chain substitution method. After formulating the concept of the considered approach, all mathematical expressions used to create models containing up to four factor variables are presented and summarized. The scientific novelty of the study is in the obtained new equations for determining the individual factor influences by the method of averaged chain substitution and the method of analogy for five-factor additive or difference-multiplicative and for five-factor additive or difference-multifactor models with an additive or different part in the numerator of the factor model. The presented mathematical expressions accurately and unambiguously quantify the impact of individual factor influences for all types of factor models and thus significantly expand the applicability of the averaged chain substitution method in the theory and practice of financial-economic analysis. The proposed formalization and algorithmization of the evaluation process makes the method easy to apply by all economic and financial analysts for the purposes of deterministic factor analysis. The methodology was applied to perform a dynamic deterministic factor analysis of the total liquidity of Monbat AD and ELHIM-ISKRA AD for the period 2017–2021, based on the consolidated annual financial statements of the companies, available on the website of the Bulgarian Stock Exchange. Full article

The digital transformation of society is a reality. Technology is becoming integral to people’s daily lives and children are growing up in the digital age. The education systems have to reflect and adapt to the new digital reality to effectively engage and prepare students for the future. Teachers have to possess digital competences at a high level, meaning that they are successfully able to use digital tools and technologies in their teaching practices. Digital competences include digital literacy, experience using educational software and platforms, and the ability to seamlessly integrate information and communication technologies (ICT) into the organization of educational activities. The current paper aims to study the opinion of teachers in Bulgarian schools regarding the possibilities of using digital technologies to achieve educational goals and the extent to which teachers integrate digital tools in their teaching activities. Teachers’ opinions about the need for specific digital competences are important. The results of the survey show that teachers in Bulgaria actively use digital technologies in their daily teaching activities (84.8%) in order to create and provide learning content to students and to provoke their active participation, and is a convenient tool for evaluating their students’ knowledge and skills and for providing effective feedback. The conducted research also identifies the necessary competences that teachers of the digital generation of learners need—skills and competences for developing authored electronic resources in various formats for students with different learning styles, as well as for working in online environments—individually and collaboratively with other teachers. Full article

The relevance of the development is determined by the possibility of testing a complex analytical methodology for forecasting the daily volatility of Bulgarian investment funds, which will support the investment community in making adequate investment decisions. The used risk attribution quantification models GARCH (1.1), EGARCH (1.1), GARCH-M (1.1) and TGARCH (1.1) are adapted to predict the volatility of investment funds. The current development focuses on forecasting the risk concentration of investment funds (in Bulgaria) through the testing of complex, analytical and specialized models from the GARCH group. The object of the study includes quantitative analysis, estimation and forecasting of daily volatility through the models GARCH, EGARCH, GARCH-M and TGARCH with specification (1.1). The research covers the net balance sheet value of forty-two investment funds for the period from 13 July 2020 to 13 July 2023, where the results of the research show that according to three of the models GARCH, EGARCH and GARCH-M with the highest risk concentration the investment fund “Golden Lev Index 30” stands out. An exception to the thus formed trend is related to the TGARCH model in which the future conditional volatility is with the “EF Rapid” investment fund. When testing the models, we found that the GARCH model and the EGARCH model successfully optimize the regression parameters of the final equation for all analyzed investment funds, and as a result, valid forecasts are formed. In the case of the remaining two GARCH-M and TGARCH models, the impossibility of applicability of the model for some investment funds was found because of the optimization procedure, in which the parameters of the models have a value of zero. The present study is a unique mechanism for forecasting the daily volatility of Bulgarian investment funds, which further assists investors in risk assessment and is a prerequisite for making adequate and responsible investment decisions. The wide-spectrum toolkit of risk forecasting models allows their testing in investment funds with different risk natures (high-risk, balanced and low-risk). From a research point of view, in future research dedicated to modeling the risk attribution of investment funds, the analytical toolkit can be enriched with the following models: QGARCH, PGARCH, GJR-GARCH, IGARCH, SGARCH, AVGARCH, NGARCH and GAS. From a statistical point of view, we can apply the analyzed models to different probability distributions in order to describe the risky nature of investment funds. Full article

ChatGPT has aroused the users’ interest and provoked educators, researchers, and educational institutions about its role in education. Its proper integration into education can support teaching and learning activities and highlight the benefits of digital technologies. ChatGPT can be an intelligent learning assistant for learners and educators, supporting personalized and adaptive learning. At the same time, ChatGPT can be used unfairly and unethically, which causes severe concerns among educators, educational institutions, and society. Educators’ attitudes regarding their application, expectations, and concerns are very important in the emergence and introduction of new technological tools in education. The current paper aims to explore the opinion of university professors at a Bulgarian university regarding the possibilities and challenges of ChatGPT in carrying out teaching activities. The findings of the conducted survey show that university professors from Trakia University in Bulgaria have an overall positive attitude regarding the implementation of ChatGPT in their teaching practice (41.4%). They perceive ChatGPT as a means to support time-consuming teaching activities (60.9%), provoke interest, activate and engage learners (59.8%), and stimulate their critical thinking and creativity (47.1%). In parallel, the university professors are concerned about possible risks of its unethical use that threaten the validity and fairness of assessment practices. The most severe problem for them is the danger that learners will completely trust ChatGPT without checking the authenticity of the generated texts (73.6%), which can negatively affect the acquisition of knowledge and skills. Full article

Satureja pilosa Velen., S. coerulea Janka and S. kitaibelii Wierzb. ex Heuff. are Balkan endemic species, and they are distributed in restricted territories, primarily found in dry grasslands, rocky slopes, and stony habitats. This study presents the results of the first embryological and micromorphological analyses of three Satureja species (S. pilosa, S. kitaibelii, and S. coerulea) from the Bulgarian flora. The aim of this study was to establish the features of the male and female reproductive sphere, as well as surface characteristics of leaves, stem, and calyx in order to understand the mode of reproduction, character, size and state of species populations and delimitation. For the embryological study, flowers and flower buds in different developmental stages were collected from plants of natural populations and treated with the classic paraffin method. Reproductive capacity was assessed using the following approaches: (1) acetocarmine test for pollen viability, (2) tetrazolium test (TTZ) for seed viability, and (3) germination test. The surfaces characteristics of leaves, stem, and calyx were analyzed by scanning electron microscopy (SEM). As a result, the study revealed the structures of the male (M) and female (F) generative spheres as well as the processes of gamete development, pollination, and endosperm and embryo formation. It was found that the three Satureja species exhibited a high pollen viability but low seed viability and germination. The SEM analysis showed both common and distinct micromorphology features regarding epidermis, calyx and stem surfaces among the three Satureja species. Notably, the S. coerulea surfaces (leaves, calyx, stem) were clearly distinguishable from the other two Satureja species. Regarding the nutlet surfaces, it was observed that the exocarp surfaces of S. coerulea and S. kitaibelii have a reticulate convex type surface and comprise two types of cells: (1) highly bulging, bubble-like cells; and (2) flat cells with numerous striations. On the other hand, the exocarp of S. pilosa displayed rectangular or polygonal shapes without bubble-like cells, and it had a tabular to slightly convex type surface. Additionally, nutlets (seeds) of both S. coerulea and S. pilosa exhibited distinct papilla formations resembling non-glandular trichomes seen on the ends of the nutlets for S. coerulea and over the entire surface for S. pilosa. The characteristics of the embryological structures and processes, along with the absence of apomixis, characterized the three studied Satureja species as sexually reproducing. The established balanced processes and stable structures contribute to their high reproductive potential and population stability. However, these traits may also decrease their adaptability to environmental changes. Full article

In the conditions of global climate change and invasion of new diseases and pests, the utilisation of the local gene pool is a vital step towards sustainable agriculture. Local cultivars and forms are generally considered as better adapted to the conditions of the originating region than widely spread commercial cultivars bred elsewhere. In order to collect, study, and preserve old and local fruit and vine cultivars and forms, a series of expeditions have been conducted throughout Bulgaria under the frame of project KP-06-N46/3 funded by the National Science Fund of the Bulgarian Ministry of Education and Science. During these scientific expeditions, several local cherry forms were discovered without visual symptoms of brown rot Monilinia laxa (Aderh. and Ruhl.) Honey or cherry leaf spot Blumeriella jaapii (Rehm) Arx. To confirm the degree of resistance/low susceptibility of the specimens, laboratory tests with artificial inoculations of fruits and leaves were conducted. In the current study, two specimens found in Damyanovo region (a village in the municipality of Sevlievo, Gabrovo Province, in northern central Bulgaria) were included. They were compared to two old local cherry cultivars, ‘Volsko sartse’ and ‘Ranna cherna edra’, and two new selections of FGI-Plovdiv, ‘Asparukh’ (El.17-90) and ‘Kossara’, using ‘Bigarreau Burlat’ as reference cultivar for resistance to economically important diseases. The artificial inoculations confirmed the field observation of the cherry specimen with designation SM-58 with 0.00% of infected fruits. Therefore, it is recommended for use in the breeding programme of the Fruit Growing Institute, Plovdiv for the creation of new cultivars. Full article

Serious economic damages in many regions of the world were caused by the changes in agroclimatic resources during the last 2–3 decades. The Balkan Peninsula is much affected by the temperatures rising, changes in the distribution of precipitation, and the increasing frequency of extreme events—basically, droughts and frosts. Bulgarian agriculture is developed under various agrometeorological conditions. The climate of the country is characterized by the atmosphere and soil moisture deficit in the time of active crop vegetation and yield formation. The aim of this research is to assess the changes in agrometeorological conditions for the growth of the main grain crops and the possibilities for reaction through agro-technologies. Furthermore, the features of contemporary varieties and hybrids of spring and autumn cereals will be taken into account. The next important factor is the specific requirements for hydro-thermal conditions at different phenological phases of agricultural crop development, i.e., sums of the temperatures and precipitations. Agro-technologies react to tendencies in changing agrometeorological conditions. For the adaptation of agro-technologies, the maximum use of natural agroclimatic resources should be included in activities for overcoming unfavorable conditions, as well as the increased frequency of extreme events. A detailed assessment of the agrometeorological conditions is necessary to choose the suitable agro-technology activity. The analysis of the main meteorological elements—temperatures, precipitations, air humidity, wind speed, and solar radiation for thirty years (1986–2015) was used to assess the changes in agrometeorological conditions on agricultural lands in Bulgaria. Appropriate agro-technical activities for growing the main grain crops are proposed in accordance with the observed changes. Full article

Through its natural or cultivated insular population distribution, Ilex aquifolium L. is a paramount species which is exceptionally suitable for studying phenotypic variability and plasticity through the assessment of morphological, physiological, biochemical and genomic features with respect to acclimation and/or adaptation efficiency. The current study is focused on four insular populations of Ilex aquifolium from Eastern Europe (i.e., in Romania, Hungary, Serbia and Bulgaria), and presents an initial evaluation of phenotypic variability in order to conclude our research on phylogenetic relationships and phytochemical profiles, including several descriptive and quantitative morphological traits. Taken together, the data from different methods in this paper indicate that the Bulgarian and Romanian populations can be distinguished from each other and from Serbian and Hungarian populations, while the latter show a higher level of resemblance with regards to their quantitative morphological traits. It is likely that these morphological traits are determined through some quantitative trait loci implicated in stress responses generated by light, temperature, soil water, soil fertility and salinity conditions that will need to be analysed in terms of their physiological, genomic and metabolomics traits in future studies. Full article