Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences. Feed

Research Into the Dynamics of Fire Development and the Efficiency of the Fire Alarm System in a High-Rise Building

Sun, 18 Jan 2026 00:00:00 GMT

Fires in high-rise residential buildings can lead to human casualties and significant property damage. Therefore, ensuring fire safety in these buildings is an urgent task. The results of the Fire Protection System simulation of the development of a fire in a residential apartment showed that open windows and doors of the room, as well as the wind speed outside the window, affect the dynamics of fire development and the spread of non-hazardous fire factors. However, when the wind speed outside the window is 7.0 m/s, due to draft and cooling, the hazardous factors of the fire do not reach critical indicators for humans. This makes the evacuation process safer for people. The impact of the position of windows and doors, and the wind outside the window on the time of detection or failure of fire detectors was determined. It was determined that even if the current regulatory requirements for installing fire detectors are met, when the wind speed outside the window is 7.0 m/s, only the smoke detector located in close proximity to the source of the fire and having increased sensitivity is triggered. The results demonstrate the need for an adaptive approach to the placement of detectors in high-rise residential buildings.

Analysis of Fire Causes and Assessment of Fire Risk (Using the Example of Hotels)

Sun, 18 Jan 2026 00:00:00 GMT

Fire safety management in hotels is a critically important area in today’s conditions. Assessing fire risks in hotels requires a comprehensive approach, which includes not only the development and implementation of effective fire detection and extinguishing systems, but also the organisation of training for staff and guests in actions in case of danger. In this context, the analysis of fire risks and fire safety management in hotels becomes extremely important to ensure the safety of all those present in hotel premises. The main idea of the article is to identify the dominant factors of fire risks in hotels in Ukraine, which contribute to the classification and identification of patterns of their impact on the state of fire safety in hotels. Based on cluster analysis, a close relationship was established between the number of fires that occurred due to malfunctions of electrical appliances depending on their type at the level of 0.98–0.88, and the degree of fire resistance and number of floors of hotels. An integral risk indicator was proposed, which takes into account three types of risks and makes it possible to assess the level of security of the hotel building.

Effects of Biotextile-Related Nanoparticles and Microparticles (Succinite, Ag, SiO2,Al2O3) on Barley (Hordeum vulgare) Immature Pollen Cells

Sun, 18 Jan 2026 00:00:00 GMT

With the rapid progress of nanotechnology, nanoparticles and microparticles are extensively studied for their diverse applications, alongside growing concerns regarding their environmental impact and potential effects on living organisms. Nanoparticles, due to their size, can penetrate cell membranes, accumulate intracellularly, and influence molecular mechanisms, while microparticles tend to adhere to cell surfaces, affecting cellular transport pathways. This study investigates the short-term impact of four types of nano- and microparticles (SiO2 (0.2–0.3 μm), Al2O3 (2.5 μm), Ag (0.5–1 μm), and succinite (5 nm – 3 μm)), specifically those explored for developing novel biotextile materials with specialised protective capabilities against harsh environments. As a model we used Hordeum vulgare immature pollen cells (microspores). Microspores were incubated in vitro for 1.5 hours in media containing these particles. Relative cell autofluorescence was measured, and DNA changes were assessed using the inter-primer binding site (iPBS) fingerprinting method. Our results indicate that Al2O3 and SiO2 microparticles had a suppressing effect on microspore autofluorescence, whereas succinite (amber) particles had an increasing effect. Ag particles showed no significant effect on microspore fluorescence under the studied conditions. Crucially, the iPBS method revealed visible changes in the amplified barley microspore DNA spectrum in samples exposed to SiO2, Al2O3, or succinite nano- and microparticles, suggesting potential genotoxic effects. These findings underscore the importance of evaluating the diverse physiological and genetic responses of plant reproductive cells to various types of engineered nanoparticles and microparticles.

Long-Term Baltic Salmon Salmo salar (L.) Restocking Experience in Latvia

Sun, 18 Jan 2026 00:00:00 GMT

Artificial propagation of salmonids in Latvia has a long-standing history, spanning nearly 140 years, periodically interrupted and resumed after the First and Second World War. Between 1939 and 1974, a cascade of three hydroelectric power plants was built on Latvia’s most important salmon river, the Daugava, thereby preventing access to spawning areas. To maintain salmon stocks at an economically significant level, a scientifically based restocking programme of salmon stocks has been established and continues to this day. Over the years, salmonid rearing techniques developed, initially growing them to the larval stage, then to the juvenile stage, and finally to physiologically mature, saltwater-adapted smolts. The artificial propagation of salmon was not interrupted even during the collapse of the Soviet Union. To compensate for the loss of salmonid resources, the Institute of Food Safety, Animal Health, and Environment BIOR performs salmonid rearing, supplementing natural fish stocks with more than one million salmon and sea trout juveniles annually. The salmon stock in the Daugava River basin has been successively artificially maintained for more than fifty years, and the national restocking programme supports salmon stocks in the Gauja and Venta rivers with expectation of the wild stock stabilisation.

Pre-Procedure Risk Stratification and Outcomes After Percutaneous Transhepatic Biliary Drainage for Malignant Obstruction: A Prospective Single-Centre Study

Sun, 18 Jan 2026 00:00:00 GMT

Recent studies have identified multiple factors associated with increased mortality and morbidity in patients undergoing percutaneous biliary interventions. Although several risk stratification scales have demonstrated value in identifying high-risk patients, evidence remains limited for populations with advanced frailty and short life expectancy, where quality of life is a primary concern. This observational study aimed to replicate previously reported results using a risk stratification scale and explore additional risk factors associated with outcomes. Thirty-seven patients were assessed before the procedure using the Eastern Cooperative Oncology Group (ECOG) scale and a predefined scoring system. Mortality at 7, 30, and 90 days was determined through national registry data. While we were unable to reproduce previously published favourable results using the modified risk scale, the ECOG score was confirmed as an independent predictor of 30-day mortality (p = 0.028). Infectious complications were common after percutaneous biliary drainage (PBD), and antibiotic prophylaxis did not influence short-term mortality. Individualised pre-procedural risk assessment is recommended for oncology patients undergoing PBD with palliative intent.

Surgical Outcomes Following Fluorescence Cholangiography-Guided Laparoscopic Cholecystectomy in Patients with Moderate Acute Cholecystitis

Sun, 18 Jan 2026 00:00:00 GMT

In patients with moderate acute cholecystitis, there is an increased risk of iatrogenic bile duct injury during laparoscopic cholecystectomy. Fluorescence cholangiography (FC) can improve visualisation of extra hepatic bile ducts intra-operatively and can assist in achieving critical view of safety (CVS) principles. The present prospective observational study focuses on the efficacy of FC with indocyanine green (ICG) in patients with moderate acute cholecystitis who underwent laparoscopic cholecystectomy at our department between October 2021 and April 2024. We compared visualisation rates of extrahepatic bile ducts, both before and after achieving CVS along with FC-ICG. We were also interested in the post-operative surgical outcomes. Descriptive statistics were used to present our results. In our cohort of 33 patients (52% female) with moderate acute cholecystitis, the acute gangrenous subtype (56.2%) was the most common followed by the acute phlegmonous form (43.8%). The median operative time was 85 minutes with three patients requiring conversion to an open approach. When comparing before and after CVS achievement, FC-ICG improved the visualisation of extrahepatic biliary tree structures including the cystic duct (52% vs 70%), common bile duct (48% vs 70%), and common hepatic duct (33% vs 46%). Median hospitalisation duration was six days with no patient reporting any post-operative complications. Consequently, the median post-operative patient well-being score was 80%. FC-ICG improves the visualisation of extrahepatic biliary tree structures during laparoscopic cholecystectomy in patients with acute moderate cholecystitis, thereby increasing success rates and reducing complication rates.

On a Numerical Method for Solving the Problem of Water Displacement by Gas

Sun, 18 Jan 2026 00:00:00 GMT

The objective of the work is to develop efficient numerical methods for solving the problem of displacement of one fluid by another in a porous medium, arising during the development and operation of oil and gas fields, and creation and operation of underground gas storage facilities in aquifers. At present, when conducting hydrodynamic calculations of underground gas storage facilities, methods are used that do not fully take into account the real properties of the gas and water reservoir, as well as the specifics of the process. In this regard, there is a need to develop efficient numerical methods for conducting hydro gas dynamic calculations that allow to take into account the specified factors and thereby to model the process more accurately. All of the above also apply to problems arising during the operation of gas fields bordering active edge waters. The theoretical justification for the possibility of storing gas in horizontal aquifers with a sufficiently sealed clay roof was first given by Charny et al. (1969). Subsequently, various approximate methods were proposed, and hydrodynamic calculations of water displacement by gas were carried out on their basis. Numerical implementation of the algorithm was carried out by the finite difference method on a moving grid. The proposed difference-iteration method in moving grids can be used to determine a rational method of influencing the reservoir.

Expression Levels of Local Protective Factors in Oral Mucosa: A Comparative Pilot Study Between Healthy Patients and Chronic Periodontitis Patients

Sun, 18 Jan 2026 00:00:00 GMT

This study examined the expression of local protective factors — Gal-10, hBD-3, hBD-2, LL-37, and CD163 — in the oral mucosa of chronic periodontitis patients compared to healthy patients. Seven chronic periodontitis patients and five control group patients of Latvian nationality were included, all meeting the selection criteria. Tissue samples underwent haematoxylin and eosin staining and immunohistochemical analysis. Results were analysed semi-quantitatively with Mann–Whitney U test and Spearman’s correlation. Routine staining showed moderate to significant infiltration, without intergroup differences. Controls displayed low-moderate Gal-10, hBD-3, hBD-2 expression, while LL-37 and CD-163 were rare. Chronic periodontitis samples showed few Gal-10, hBD-3, hBD-2, LL-37 positive cells, with CD-163 only occasionally present. No significant differences were found via Mann–Whitney U test. Spearmen’s rank correlation revealed significant correlations: in the control group — between hBD-2 and LL-37 (epithelium), hBD-3 (connective tissue) and CD-136 (macrophages), and LL-37 (epithelium) along with GAL-10 (connective tissue). In chronic periodontitis — one strong correlation between HBD-2 (connective tissue) and HBD-3 (epithelium). Similar local protective factors expression between chronic periodontitis patients and controls suggest comparable local immune status in the Latvians. These results highlight the complexity of oral immunity and the need for further studies on localised immune components in periodontitis.

Development of a Clinical Proforma for the Assessment of Women with Pelvic Organ Prolapse Undergoing Surgical Management

Sun, 18 Jan 2026 00:00:00 GMT

Pelvic organ prolapse (POP) prevalence can reach up to 50% in certain populations, with symptomatic POP causing a significant burden and diminishing the quality of life. Critical information is often omitted from medical records, and thus thorough assessment is essential for optimal surgical management. This study aimed to determine if implementing a POP-specific, evidence-based clinical proforma would increase the completeness of documentation for women undergoing surgical management. A retrospective audit was conducted, comparing the completeness of documentation from the existing general proforma group (n = 110) with a POP proforma group (n = 193). Completeness was assessed against 33 criteria. Documentation completeness either improved or remained unchanged across all criteria following proforma implementation. Key improvements included POP-Q staging documented in 100% (vs. 59.1% previously) and compartment measurements in 81.3% (vs. 37%) of preoperative records. The use of a structured, unified POP-specific proforma improved the completeness of clinical documentation, supporting the adoption of standardised assessment tools in urogynecological practice.

Influence of a Magnetic Field on the Structural and Morphological Properties of the Hydrothermal Growth of ZnO Nanostructure

Sat, 27 Sep 2025 00:00:00 GMT

The effect of a permanent magnetic field (500 Gauss) on the hydrothermal preparation of zinc oxide (ZnO) nanostructures was studied. Using this approach, ZnO was deposited on various substrates, including insulator/glass, semiconductor/silicon, and conductor/FTO-glass. A horizontal substrate position without and with the magnetic field (B=0G,andB=500 G) was investigated, respectively. The surface morphology and crystalline structure of the produced samples were characterised by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The main finding of this work was to assess improvement in crystal structure parameters and morphology enhancement by using magnetic fields.

On a Method of Solving Non-Isothermal Two-Phase Filtration Problems

Sat, 27 Sep 2025 00:00:00 GMT

A numerical method is considered based on the numerical modelling of the problem of a nonisothermal process of nonlinear filtration of two-phase fluid, taking into account relative phase permeabilities and capillary forces. Numerical implementation of the algorithm is carried out using the finite difference method on an adaptive grid. The proposed difference-iterative method in adaptive grids can be used to find a rational method for treating the oil layer. The following issues are studied by means of numerical calculations: assessment of the efficiency of hot water injection compared to cold water injection in the development of oilfields containing medium and high viscosity oils, impact of the periodicity of hot and cold water injection on the oil recovery, impact of preliminary water saturation on the ultimate oil recovery in case of hot water injection, and assessment of the impact of thermal effect on the oil recovery from the depletion layer.

Evaluating BCG Therapy in High- and Low-Grade Non-Muscle-Invasive Bladder Cancer: Insights from a Latvian Hospital (2019–2024)

Sat, 27 Sep 2025 00:00:00 GMT

Bacillus Calmette-Guérin (BCG) immunotherapy is a cornerstone treatment for managing non-muscle invasive bladder cancer (NMIBC), which is one of the most common cancers in Europe. However, real-world adherence and outcomes vary significantly. The aim of the study was to evaluate recurrence free survival (RFS), progression free survival (PFS), overall survival (OS), and treatment implementation among the NMIBC patients treated with BCG, compared to those treated with transurethral resection of bladder tumour (TURB) alone at Latvia’s second largest university hospital. A retrospective cohort study was conducted at Pauls Stradiņš Clinical University Hospital. Patients diagnosed with NMIBC between 2019 and 2024 were divided into two groups: BCG-treated and TURB-only. Kaplan-Meier analysis was used to evaluate survival outcomes, and Cox regression assessed predictors of recurrence. Among 111 BCG and 167 TURB-only patients, three-year RFS was significantly higher in the BCG group for T1HG patients (75% vs. 45%, p < 0.05). BCG was associated with a 59% lower recurrence risk (HR: 0.41, 95% CI: 0.23–0.77; p < 0.05). No significant differences were observed in PFS or OS. Only 4% of BCG patients completed optimal maintenance therapy. BCG significantly improves RFS in T1HG NMIBC, but is limited by poor maintenance adherence, thus highlighting the need for better implementation and larger prospective studies.

Selection of Novel Reference Genes for qPCR Normalisation in the MDA-MB-436 Breast Cancer Cell Line

Sat, 27 Sep 2025 00:00:00 GMT

Nowadays reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) is a widely used laboratory method for evaluating gene expression and its differences in various conditions. However, to increase the credibility and accuracy of the results, they are usually normalised against a pair or a triplet of reference genes in which expression is found to be stable across the conditions investigated in the study. This study aims to find suitable reference genes for evaluating gene expression in different confluences in the triple-negative breast cancer cell line MDAMB-436. A candidate reference gene set comprised of 30 genes was analysed in the study. The expression of these genes and four different genes of interest was analysed in over 90 different samples from the cell line MDA-MB-436 and then the most stable reference genes were determined using algorithms such as NormFinder, RefFinder, etc. All reference genes exhibited robust stability while the most stable reference genes were found to be MYL12A; RBX1; PUM1 and PFN1. The results of this study will provide other researchers around the world with knowledge about the most stable reference genes across different confluences in cell line MDA-MB-436 and will facilitate further research in this field.

Multidisciplinary Studies of Environment and Early Farming in Neolithic Settlements of Lubāns Wetland

Sat, 27 Sep 2025 00:00:00 GMT

The paper summarises data from previous and new multidisciplinary studies of Lubāns wetland, a unique place with a complex geological structure, a unique hydrological regime, including lake level fluctuations. There was intensive Stone Age population around Lake Lubāns. Changes in the palaeogeographical conditions in the vicinity of Lake Lubāns have significantly influenced both the nature of the vegetation and the landscape. Human impact on the landscape and vegetation in Stone Age settlements Zvidze, Sūļagols, Lagaža, Eiņi, Asne, and Abora and their surroundings was investigated using biostratigraphic studies of sediments, plant macro-remains, pollen records, and radiocarbon dates. The aim of the research was to determine the time of the beginning of agriculture in the Lubāns wetland. So far Cerealia grains have not been found in macro-remains, but pollen, mainly barley (Hordeum), has been found in samples dated to the Middle Neolithic.

Evaluation of Ribes nigrum L. Prospective Hybrids in Estonia

Sat, 27 Sep 2025 00:00:00 GMT

The evaluation of promising hybrids of blackcurrant (Ribes nigrum L.) was carried out in 2017–2019 at Polli Horticultural Research Centre of the Estonian University of Life Sciences, in South Estonia. The objective of the Estonian blackcurrant breeding programme is to produce cultivars that are winter hardy, resistant to gooseberry mildew (Sphaerotheca mors-uvae (Schw.) Berk.) and gall mite (Cecidophyopsis ribis Westw.), well suited to machine harvesting, and with good yield and quality of fruits. The evaluation plot was established in the autumn of 2015. Twenty blackcurrant promising hybrids from the Estonian blackcurrant breeding programme and cultivars ‘Pamyat Vavilova’ and ‘Titania’, as the standard, were evaluated for beginning of flowering and fruit ripening (expressed in growing degree days, GDD), winter hardiness, resistance to diseases and pests (expressed in scores 1–9), number of fruits per cluster, drop of flowers and young fruits (%), yield (kg per bush), weight of fruit and content of the soluble solids (°Brix). Fruits were analysed for titratable acids, anthocyanins and polyphenols. The evaluation revealed the best blackcurrant genotypes to be: 1-11-3 (‘Asker’ × ‘Intercontinental’), 6-11-3, 6-11-5 (‘Karri’ × ‘Pamyat Vavilova’) and 7-11-5 (‘Karri’ × SRI 9154-3). All these genotypes are winter hardy and visually resistant to gall mite and gooseberry mildew, and produced good yields and large fruits.

Risk Factors for Bone Mineral Density in Women: A Cross-Sectional Study

Sat, 27 Sep 2025 00:00:00 GMT

Factors associated with bone mineral density (BMD) have been studied, but the results are conflicting. The aim was to identify health risks and protective factors for BMD in regularly physically active (PAG) and ³ 65-year-old (+65G) women and a control group (CG). 164 women (PAG = 33; +65G = 35; CG = 96) completed a questionnaire on diet recall, and blood analysis and DXA were used. For statistical analysis, the chi-squared test, Student’s t-test, and univariate and multivariable linear regression analysis were performed. PAG had lower and +65G higher levels of fat mass (FM), fat%, and body mass indices. PAG, +65G, and CG all received P% of the recommended daily amount of energy, 12%, 26%, and 26%, respectively, and there were micronutrient deficiencies in the diet (especially of vitamin D and calcium). BMD was positively associated with fat-free mass (FFM) and negatively with older age in all regions. FFM and FM were positively, and older age and additional calcium intake — negatively associated with whole body BMD. BMD is strongly related to body composition parameters and age. Women’s BMD needs to be addressed throughout the life cycle.

Alterations in Gut Microbiota After Antibacterial Treatment Due to Concomitant Disease Among Ambulatory Paediatric Patients

Thu, 15 May 2025 00:00:00 GMT

Antibacterial treatment is an important factor in shaping gut microbiota in children. The study aims to assess the effects of antibacterial therapy on microbiota composition. Parents of children with antibacterial treatment due to a concomitant disease submitted three children’s faecal samples (before the treatment, one week, one month after the treatment). Relative Abundance (RA) of bacterial taxa (16 rRNS) was compared between baseline and follow-up samples. Among 20 participants (median age 22 months) shifts within a month were noted for Bifidobacterium (46.80% vs 28.93% vs 41.50%; p = 0.087); Blautia (10.80% vs 8.94% vs 11.50%; p = 0.06), Anaerostipes (3.70% vs 0.32% vs 7.31%; p = 0.032), and Ruminococcaceae UCG-004 (p = 0.020) at baseline/one week/one month, respectively. Median RA of Eggerthellaceae decreased from 0.08% at baseline to 0.01% at one month (p = 0.040), while RA of Veillonellaceae increased from 0.01% at baseline to 0.04% at one month (p = 0.022). In conclusion, among the studied toddlers, antimicrobial treatment was associated with temporal alterations of gut microbiota, although a tendency towards the recovery of the pre-treatment microbial composition was noted. Persistent shifts of certain bacterial families could be minor markers for long-term changes in microbiota composition that should be analysed in dynamics.

83rd International Scientific Conference on Medicine and Health Sciences of the University of Latvia: Oncology

Thu, 15 May 2025 00:00:00 GMT

Preventing Postoperative Delirium in Older Adults with Hip Fracture: A Randomised Controlled Trial of a Reorientation Intervention

Thu, 15 May 2025 00:00:00 GMT

Postoperative delirium (POD) is a common complication in geriatric patients undergoing hip fracture surgery. This study evaluated the effectiveness of a short postoperative reorientation intervention in reducing the incidence and duration of POD. In this randomised controlled trial, 62 patients aged > 75 undergoing hip fracture surgery were recruited. Preoperative cognitive assessments were conducted using the Montreal Cognitive Assessment (MOCA) and delirium screening with the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Daily evaluations using CAM-ICU were performed for seven postoperative days. The intervention group received structured reorientation sessions and a five-minute news briefing daily. The trial was comprised of 62 participants (80.6% female, mean age 82 ± 6 years), with 49% having preoperative cognitive impairment associated with delirium development (p = 0.02). Incidence rates of delirium were similar in both groups: 20% vs. 25% in controls (p = 0.82). However, the duration of delirium was significantly shorter in the intervention group (4 vs. 6 days, p < 0.01). Patients in the intervention group were four times more likely to achieve delirium resolution within 7 days (relative risk (RR): 4.13, p = 0.03). The reorientation intervention significantly reduced the duration of delirium post-hip fracture surgery, but did not affect overall incidence rates.

83rd International Scientific Conference on Medicine and Health Sciences of the University of Latvia: Basic Medical Science and Pharmacy

Thu, 15 May 2025 00:00:00 GMT