Critical Level Research Articles

Gtfswizard: a set of tools for exploring and manipulating general transit feed specification in R language

The public transport system is fundamental to sustainable urban mobility, offering cost-effectiveness, scalability, and environmental benefits while addressing equity challenges. This study identifies a research gap in existing tools for General Transit Feed Specification (GTFS) data analysis, which often lack integration, usability, and flexibility for comprehensive transit planning. In response, GTFSwizard is developed, a R package that facilitates exploration, and manipulation of GTFS feeds. To demonstrate its potential, a case study in Fortaleza, Brazil, evaluates interventions designed to enhance accessibility equity. The interventions, which include bus corridors, optimized boarding, and increased frequency, were tested exclusively using GTFSwizard, which, with simple functions, allowed the analysis and modification of GTFS data as well as the estimation of accessibility. Results showed an 18% reduction in the number of individuals under critical accessibility levels, a reduction in accessibility inequity, and operational efficiency gains, including a 2.7% reduction in required fleet size and a slightly increase of 0.35% in vehicle-kilometer traveled. The ease with which the scenarios are generated highlights the package's ability to perform GTFS analysis and manipulation in a simple and unified manner.

Indication of the sensitivity of Pinaceae species growing in Eastern Central Europe to ground-level ozone pollution.

This study focused on testing the response of the assimilation apparatus of evergreen Pinaceae species to increasing levels of oxidative stress simulated in manipulative experiments. Needles were collected from mature individuals of Pinus mugo, Pinus cembra, Pinus sylvestris, Abies alba, and Picea abies at the foothill (FH) and alpine treeline ecotone (ATE) in the High Tatras (Western Carpathians). The injury index (INX), quantified by the modified electrolyte leakage (EL) method, indicated severe needle damage due to exposure to extremely high levels of O3. Ozonation induced changes in the chemical composition of the needles, which were detected via gas chromatography-mass spectrometry. The oxidative stability (OxS) indicator derived from INXs was used to determine the stomatal O3 flux-based critical level CL(OxS), with the threshold value of OxS at -0.05, corresponding to 5% injury to the needles. Assessment of the phytotoxic ozone dose (POD0) under ambient O3 and field environmental conditions during the 2023 growing season via CL(OxS) revealed that the studied species utilised between 18% (Abies alba FH) and 33% (Pinus mugo ATE) of their O3 tolerance potential. These results support our hypothesis that Pinaceae species growing in the High Tatras, which are part of the Alpine biogeographical region of Eastern Central Europe, are vulnerable to O3 concentrations significantly higher than the typical ambient O3 level in the natural environment.

Reliability-based reinforcement learning driven maintenance policy optimization

The study presents a reinforcement learning (RL) method called the Q-learning algorithm to determine the best maintenance policy for equipment. This involves an artificial intelligence agent making decisions and an environment representing the equipment. The agent creates maintenance policies and takes actions, while the environment determines state transitions and rewards based on the actions chosen. The optimization of the maintenance policy starts with predicting equipment reliability using sensor data. This prediction method combines Back Propagation Neural Network (BPNN) algorithms with the Boxing Match Algorithm (BMA), an evolutionary meta-heuristic algorithm. A novel weight update strategy enhances the performance of artificial neural networks in reliability prediction. This integrated model, BMA-BPNN, aims to improve the accuracy of forecasted reliability. The study involves forecasting equipment reliability to determine critical levels, incorporating cost and risk considerations into decision-making for optimizing maintenance policies. As a result, the Q-learning algorithm is used to identify the best maintenance actions based on equipment reliability. Implementing an automated maintenance system that considers equipment reliability and costs can help reduce accidents resulting from maintenance program deficiencies. This study thus contributes to the field by providing an efficient approach to equipment maintenance.

The Ability of SOCS1 to Cross-Regulate GM-CSF Signaling is Dose Dependent.

Suppressor of cytokine signaling (SOCS) 1 is a key negative regulator of interferon (IFN), interleukin (IL)12, and IL-2 family cytokine signaling through inhibition of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway. To investigate the temporal induction of SOCS1 in response to cytokine in live cells and its selective regulation of signaling pathways, we generated a mouse expressing a Halo-tag-SOCS1 fusion protein (Halo-SOCS1) under control of the endogenous Socs1 promoter. Homozygous Halo-SOCS1 mice (Halo-Socs1KI/KI) were viable with minor T cell abnormalities, most likely due to enhanced Halo-SOCS1 expression in thymocytes compared with the untagged protein. IFNγ and IL-4 induced Halo-SOCS1 expression in macrophages derived from Halo-Socs1KI/KI mice, and a critical level of SOCS1 expression was required for inhibition of both IFNγ and granulocyte macrophage-colony stimulating factor (GM-CSF)-driven JAK-STAT signaling. In contrast, IFNγ priming to induce SOCS1 did not cross-regulate IL-4 signaling. This study indicates that while SOCS1 expression needs to exceed a critical threshold to inhibit IFNγ signaling, its selective regulation of cytokine signaling results from an as yet undetermined, level of regulatory control.

COOLING EFFECT OF DIFFERENT TYPES OF MATERIALS IN AN AVIONICS SYSTEM

Equipment used in the aviation industry heats up over time depending on working conditions. It is possible to preserve properties of equipment affected by heat by either cooling the system and returning it to initial conditions or producing the system from materials that are not affected by heat. One of the areas where nanocomposite materials might be used is avionic systems in the aviation and space industry. These systems are structures in which elements such as sensors, cabling, and processors, which form the basis of the electronic structure of flight, are brought together in very small volumes. It is important that the material used in these structures is light and has high strength as well as corresponding electromagnetic properties. In this study, the thermal analysis of vapor-grown carbon fiber (VGCF) nanocomposite materials produced by adding them to the epoxy matrix in terms of the thermal performance of avionic boxes was carried out by comparing them with thermal properties of aluminum. As a result of the findings obtained from thermal analysis studies carried out in four stages, it was observed that by using VGCF composite instead of aluminum, approximately 23% improvement in temperature output and 17% improvement in thermal load was achieved. Another outcome obtained from the analysis was the cooler capacity. If VGCF is preferred instead of aluminum in avionics box manufacturing, a 37.5% improvement is achieved in terms of cooler capacity. Another important finding is the time to reach critical temperature levels. VGCF reaches the steady state 163.5% faster than aluminum. Thus, it is anticipated that energy efficiency will be increased with the use of lightweight and high-strength nanocomposite materials, which is considered one of the most important goals of the aviation industry.

Unravelling neuroregenerative and neuroprotective roles of Wnt/β-catenin pathway in ischemic stroke: Insights into molecular mechanisms.

Stroke is a serious condition often resulting in mortality or long-term disability, causing cognitive, memory, and motor impairments. A reduction in cerebral blood flow below critical levels defines the ischemic core and penumbra: the core undergoes irreversible damage, while the penumbra remains viable but functionally impaired. This functional impairment activates complex cell signaling pathways that determine cell survival or death, making the penumbra a key target for therapeutic interventions to prevent further damage. The Wnt/β-catenin (WβC) signaling pathway has emerged as a potential neuroprotective mechanism, promoting neurogenesis, angiogenesis, neuronal connectivity, and maintaining blood-brain barrier integrity after stroke. Activation of the WβC pathway also mitigates oxidative stress, inflammation, and apoptosis in ischemic regions, enhancing its neuroprotective effects. However, the overexpression of GSK3β and DKK1, or the presence of their agonists, can counteract these benefits. This review explores the therapeutic potential of WβC signaling, highlighting the effects of pharmacological modulation through antagonists, agonists, synthetic chemicals, natural products, stem cells, and macromolecules in preclinical models of ischemic stroke. While preclinical evidence supports the benefits of WβC activation, its role in human stroke requires further investigation. Additionally, the review discusses the potential adverse effects of prolonged WβC activation and suggests strategies to mitigate them. Overall, WβC signaling holds promise as a therapeutic target, offering insights into stroke pathophysiology and informing the development of novel treatment strategies.

Genetic Rescue of the Dinaric Lynx Population: Insights for Conservation From Genetic Monitoring and Individual-Based Modelling.

Inbreeding depression poses a severe threat to small populations, leading to the fixation of deleterious mutations and decreased survival probability. While the establishment of natural gene flow between populations is an ideal long-term solution, its practical implementation is often challenging. Reinforcement of populations by translocating individuals from larger populations is a viable strategy for reducing inbreeding, increasing genetic diversity and potentially saving populations from extinction. The Dinaric population of Eurasian lynx (Lynx lynx) has faced high inbreeding levels, with effective inbreeding reaching 0.316 in 2019, endangering the population's survival. To counteract this, population reinforcement was implemented between 2019 and 2023, involving the translocation of 12 individuals from the Carpathian Mountains to the Dinaric Mountains of Slovenia and Croatia. We conducted comprehensive genetic monitoring in this area, gathering 588 non-invasive and tissue samples, which were used for individual identification and estimation of population genetic parameters. We used stochastic modelling to assess the long-term viability of the Dinaric lynx population post-translocation and formulate effective conservation strategies. The model predicts that, despite significant improvement of genetic diversity after translocations, inbreeding will return to critical levels within 45 years. Our results highlight the fact that reinforcement is just the first step and that long-term genetic management is needed to keep the population from sliding back towards extinction. The Dinaric lynx population serves as a compelling example of genetic rescue. The lessons learnt here will be essential for ensuring the viability of the Dinaric lynx in the future and also provide a useful template for conservation of other populations and species facing similar threats.

Failure and Degradation Mechanisms of Steel Pipelines: Analysis and Development of Effective Preventive Strategies.

The increasing challenges related to the reliability and durability of steel pipeline infrastructure necessitate a detailed understanding of degradation and failure mechanisms. This study focuses on selective corrosion and erosion as critical factors, analyzing their impact on pipeline integrity using advanced methods, including macroscopic analysis, corrosion testing, microscopic examination, tensile strength testing, and finite element method (FEM) modeling. Selective corrosion in the heat-affected zones (HAZs) of longitudinal welds was identified as the dominant degradation mechanism, with pit depths reaching up to 6 mm, leading to tensile strength reductions of 30%. FEM analysis showed that material loss exceeding 8 mm in weld areas under standard operating pressure (16 bar) induces critical stress levels, risking pipeline failure. Erosion was found to exacerbate selective corrosion, accelerating degradation in high-stress zones. Practical recommendations include the use of corrosion-resistant materials, such as duplex steels, and implementing integrated monitoring strategies combining non-destructive testing with FEM-based predictive modeling. These insights contribute to developing robust preventive measures to ensure the safety and longevity of pipeline infrastructure.

A framework for remediation prioritization of unstable rock slopes based on indirect information

Prioritizing multiple potentially unstable slopes based on varying levels of criticality is an essential approach when resources are limited. This study presents a framework for planning the prioritization of unstable rock slope remediation. The prioritization of mitigation measures for these slopes is determined using deformation values derived from indirect information, such as rock classification systems. To demonstrate the application of this framework, a case study involving unstable rock slopes in southwestern China is presented. Initially, the most appropriate estimation model was chosen from among six candidates for estimating the deformation modulus of the unstable rock mass in the slope, utilizing indirect information. Subsequently, the deformation modulus, updated through Bayesian analysis, was employed to generate the corresponding deformation distributions for the rock slopes. Compared to traditional quantitative methods, the proposed framework is adaptable to various working conditions and yields more definitive results. The indirect data used in this framework are cost-effective, enabling the assessment of all unstable slopes. Moreover, the effect of the amount of indirect data and prior information on slope remediation prioritization is discussed. The proposed framework offers a valuable tool for decision-makers in planning and prioritizing mitigation measures.

Magnitude and precision of absolute blood volume estimated during hemodialysis

Background: Management of body fluid volumes and adequate prescription of ultrafiltration (UF) remain key issues in the treatment of chronic kidney disease patients.Objective: This study aims to estimate the magnitude as well as the precision of absolute blood volume ( V b ) modeled during regular hemodialysis (HD) using standard data available with modern dialysis machines.Methods: The estimation utilizes a two-compartment fluid model and a mathematical optimization technique to predict UF-induced changes in hematocrit measured by available on-line techniques. The method does not rely on a specific hematocrit sensor or a specific UF or volume infusion protocol and uses modeling and prediction tools to quantify the error in V b estimation.Results: The method was applied to 21 treatments (pre-UF body mass: 65.57 ± 13.44 kg, UF-volume: 3.99 ± 1.14 L) obtained in ten patients (4 female). Pre-HD V b was 5.4 ± 0.53 L with an average coefficient of variation of 9.8% (range 1 to 22%). A significant moderate correlation was obtained when V b was compared to a different method applied to the same data set (r = 0.5). Specific blood volumes remained above the critical level of 65 mL/kg in 17 treatments (80.9%).Conclusion: The method offers the opportunity to detect critical blood volumes during HD and to judge the quality and reliability of that information based on the precision of the V b estimate.

Peculiar features in forming gifted adolescents’ self-attitude to the inner and outer “I” as a condition for their self-fulfillment

Introduction. The article presents the survey results, revealing the peculiarities of forming self-attitude to the inner and outer “I” by talented young people. The purpose of the article is to define the nature of talented young people’s self-attitude to the inner and outer “I” and its influence on self-fulfillment. Materials and Methods. The theoretical and methodological basis of the study is the reflexive-compensatory approach. The method involves young people evaluating themselves, identifying their problems and building a program of remedial work with a teacher, which is aimed at creating conditions for successful socialization and self-development. The main methods are reviewing scholarly literature on the research problem, interviewing and testing Education students (n= 239). Results. The authors have revealed the specific features in forming self-attitude to the inner and outer "I" in talented youth. Most of the participants demonstrate excessive demands on themselves; focus on others and on the opinions of other people. At the same time, talented young people demonstrate a high level of “self-leadership” (60 %), “self-acceptance” (60 %), “self-blame” (56 %), “fairly high level of self-evaluating” (45 %), which indicates a positive perception of themselves. They have an average level of conflict. The participants are aware of their personal importance, their success and achievements, and their willingness to improve themselves is noted. They demonstrate a high level of perfectionism and are critical of their own failures. Conclusions. The study concludes that talented young people generally perceive themselves and their opportunities positively, strive for life and personal success. They are not quarrelsome. But they are not eager to be leaders with high potentials. A high level of perfectionism and criticism is accompanied by a feeling of anxiety and prevents skills of self-presentation to appear.

ALGORITHM FOR SELECTING INDUSTRIAL PARTNERS OF SCIENTIFIC AND TECHNOLOGICAL PROJECTS FOR THE PURPOSE OF IMPORT SUBSTITUTION OF HIGH-TECH MEDICAL PRODUCTS

Background. To date, approaches to the design and management of RD that justify the implementation of the most promising solutions, as well as to identify domestic companies with the required technical competencies, are not well developed and applicable in practice in the scientific and technological field. Aims: Development of an algorithm for identifying possible industrial partners to accelerate the implementation of full-cycle projects aimed at creating import-substituting products. Methods. The algorithm assumes the successive implementation of the following analytical procedures: (1) identification of defective commodity items with a critically high level of import dependence; (2) identification of foreign companies, technology leaders in niche markets; (3) analysis of the portfolio of patent documents of foreign companies - technology leaders; (4) highlighting the most promising technical solutions and approaches in the considered technological area; (5) identification of domestic companies holding relevant technical competencies; (6) identification of potential industrial partners for import substitution projects of the full innovation cycle based on non-patent information. To test the proposed algorithm, product group 9018 (Instruments and appliances used in medical, surgical, dental or veterinary sciences...) was selected in accordance with the commodity nomenclature of foreign economic activity. As the information base of the study, specialized registries, legal acts, a database of trade statistics and patent information resources were used. Results. An algorithm has been tested to identify companies capable of import substitution of high-tech goods, according to the formed ranked list according to the level of criticality of the positions of defective medical devices, through the use of patent analytics tools and the collection of non-patent information. Conclusion. The proposed algorithm can be applied to develop new approaches in the design and management of RD aimed at creating import-substituting high-tech products.

Improving the Forecast Accuracy of PM2.5 Using SETAR-Tree Method: Case Study in Jakarta, Indonesia

Air pollution in Jakarta, one of the most polluted cities globally, has reached critical levels, with PM2.5 concentrations exceeding the WHO guidelines and posing significant health risks. Accurate forecasting of PM2.5 is crucial for effective air quality management and public health interventions. PM2.5 exhibits significant nonlinear fluctuations; thus, this study employed two machine learning approaches: self-exciting threshold autoregressive tree (SETAR-Tree) and long short-term memory (LSTM). The SETAR-Tree model integrates regime-switching capabilities with decision tree principles to capture nonlinear patterns, while LSTM models long-term dependencies in time-series data. The results showed that: (1) SETAR-Tree outperformed LSTM, achieving lower RMSE (0.1691 in-sample, 0.2159 out-sample) and MAPE (2.83% in-sample, 2.98% out-sample) compared to LSTM’s RMSE (0.2038 in-sample, 0.2399 out-sample) and MAPE (3.48% in-sample, 4.05% out-sample); (2) SETAR-Tree demonstrated better responsiveness to sudden regime changes, capturing complex pollution patterns influenced by meteorological and anthropogenic factors; (3) PM2.5 in Jakarta often exceeds the WHO limits, highlighting this study’s importance in supporting strategic planning and providing an early warning system to reduce outdoor activity during extreme pollution.

Preliminary Study on Students Critical Thinking Skills on Temperature and Heat Material

This preliminary study investigates the critical thinking skills of Grade VII students at SMP Negeri 01 Belitang Jaya on the topic of temperature and heat, focusing on Ennis's critical thinking indicators. It aims to identify students' critical thinking levels based on five indicators and highlight areas needing improvement. The study uses a qualitative descriptive method, involving 154 students from five classes. Data were collected through questionnaires covering five indicators: providing simple explanations, building basic skills, drawing conclusions, providing further explanations, and managing strategies and tactics. The findings show that students excel in providing simple explanations (74.66%, high category). However, they perform moderately in building basic skills (46.79%), drawing conclusions (58.54%), and providing further explanations (41.60%). Managing strategies and tactics scored the lowest (31.20%, low category). These results suggest a need for targeted educational interventions, especially in strategy and tactics management. The study provides a reference for developing interactive teaching materials, such as augmented reality-assisted e-modules, to improve students' engagement and critical thinking skills. It lays the groundwork for innovative teaching strategies to make the learning process more effective and engaging

MEASURING THE DIGITAL LITERACY LEVELS OF UNIVERSITY STUDENTS IN THE CONTEXT OF DISINFORMATION PROBLEM IN DIGITAL MEDIA

In the globalizing world with the rapid development and spread of internet technology in the information and communication age, the transition from the information society to the network society has brought many problems, either explicitly or implicitly, besides many advantages. Especially the negative effects of digital addiction in Generation Z, which is born in the digital age and expressed as digital natives, and the fact that the audience is not aware of this situation or does not believe that it has negative effects makes it necessary to conduct research on the subject. On the other hand, the phenomenon of disinformation, which means the deliberate creation and dissemination of false and misleading information, emerges as an important problem with the spread of digital mass media. Starting from this perspective, firstly the concepts of digital media, disinformation and digital literacy were explained in this study and then a digital literacy scale was applied to university students. As a result of the study; it was found that the digital literacy levels of university students were significantly higher than the critical level in general.

Establishing optimal nutrient level of magnesium and boron in black pepper for optimization of productivity in Western Ghats of Kerala

Critical nutrient level of magnesium and boron in soil and plant biomass of black pepper (Piper nigrum) have been estimated in Western Ghats of Kerala by conducting field experiments in three seasons (2018-2020) by magnesium and boron fertilization. Nutrient management in black pepper plantations wins important value due to its wider use as spice all over the world. As black pepper plants are easily prone to Mg and B deficiency, its response to Mg in the form of magnesium sulphate and B as borax was evaluated in terms of yield, plant nutrient content and nutrient status in soil. Effect of Mg as well as B application on the other available nutrients and leaf nutrient content were also determined in the study. Response curves were fitted by plotting relative yield of black pepper with Mg and B in soil and index leaf. The graphical method of Cate and Nelson was used to derive the optimal concentrations of nutrients. The critical levels of magnesium in soil and black pepper leaves were established as 140 mg kg-1 and 0.44 % respectively. Optimum dose of magnesium sulphate for getting highest yield of black pepper was found as 120 kg ha-1 followed by MgSO4 @ 80 kg ha-1. Similarly critical limit of B in the soil and index leaf of black pepper were 0.58 and 21 mg kg-1 respectively. The maximum potential yield was obtained by applying boron as borax at 0.2% via foliar application and at a higher dosage of 2 kg per hectare through soil application.

Microbiota of complete removable dentures

BACKGROUND: Complete dentures are a valid treatment option in edentulous patients. However, the average service life of complete dentures is 4–5 years, which is frequently due to microbial contamination. AIM: To perform quantitative and qualitative assessment of microbiota on the surface of complete dentures after 1 and 4 years of use. MATERIALS AND METHODS: The study included 40 fully edentulous patients (К08.1) who used acrylic complete dentures for no more than 5 years. There were two groups (n=20 each) based on the duration of use of complete dentures: 1 year in Group 1 and 4 years in Group 2. The microbiota composition was examined by mass spectrometry. The Statistiсa 13 package was used for statistical processing of the study findings. For multiple comparisons, the parametric t-test with Bonferroni correction was used to assess intergroup differences, with p=0.05 as the critical significance level. RESULTS: Microbial contamination increased in all examined patients after using complete dentures for 1 to 4 years. Cocci and bacilli counts increased from 56±5 (105 cells/g) (р=0.03) to 107±8 (105 cells/g) (р=0.04). Anaerobe counts increased from 68±6 (105 cells/g) (р=0.0002) to 102±9 (105 cells/g) (р=0.0002). Actinobacteria counts increased from 30±3 (105 cells/g) to 143±12 (105 cells/g) (р=0.003). Gram-negative rod counts increased from 4±1 (105 cells/g) (р=0.0005) to 24±2 (105 cells/g) (р=0.0006). Yeast and mold counts increased from 977±90 (105 cells/g) (р=0.0003) to 1,587±136 (105 cells/g) (р=0.003). CONCLUSION: Within 4 years, yeast and mold counts increased by 91%, actinobacteria counts by 61%, gram-negative rod counts by 500%, and anaerobe counts by 50% in all patients. The study findings indicate that microbial contamination of dentures is directly related to the duration of their use.

A Pilot Dashboard System to Track Cumulative Exposure to Sound Levels during Music Instruction: A Technical Report.

Music-induced hearing loss (MIHL) is a critical public health issue. During music instruction, students and teachers are at risk of developing hearing loss due to exposure to loud and unsafe sound levels that can exceed 100 dBA. Prevention of MIHL in music students must be a desired action of all music educators. To promote deliberate changes in music instruction and encourage more moderate sound creation and exposure during music education, it is essential to equip the instructors with live dynamic tools to monitor the overall sound intensities during music instruction. Equally important data to convey to the instructors are information regarding the intensity and duration of sounds at specific frequency regions in the music they are generating. Unfortunately, there are no feasible techniques to track cumulative live music exposures at various frequencies nor are there any guidelines for safe music exposure. We created a visually appealing, user-friendly dashboard prototype system to display the accumulated time and intensity of sound exposure during live classes/rehearsals categorized into three frequency ranges. These visuals can be easily understood at a glance allowing musicians and instructors to make informed decisions about how to play music safely. The dashboard included a collection of circular dial graphs that displayed in real time the accumulated sound exposure in the instructor's selected frequency range and showed the percentage of the maximum daily sound exposure based on the National Institute for Occupational Safety and Health Standards (NIOSH, 1998). Although NIOSH standards are not widely applied for music exposure, we propose that these standards can be used to provide initial guidelines to develop critical levels of music exposure. Additionally, the dashboard included a color-coded equalizer that displayed the instantaneous frequency distribution of sounds to indicate if sound levels at specific frequencies were too high even for short-term exposure. Less expensive than existing technology and more convenient to use, this dashboard will enable music instructors to make informed decisions on how to best adapt their teaching approaches to protect the hearing health of their students.

Современная оценка факторов, определяющих эффективность воспроизводства рыб в низовьях р. Урал

The Aral-Caspian basin plays a crucial role in the formation of commercial fish stocks, which have been de-clining in recent years due to a decrease in the efficiency of natural reproduction due to an unfavorable hydrological regime. The results of studies carried out in 2019-2023 in the lower reaches of the Ural River on the influence of the hydrological regime and the number of producers in spawning areas on the reproduction efficiency are presented using the example of semi-migratory fish: roach, bream, walleye, carp, asp. It is shown that over the past 10 years, low- and medium-water years with a flood flow volume of 2-3 km3 prevailed, and only 3 years were high-water (more than 4 km3). Unfavorable years in terms of water content had a negative impact on the efficiency of fish reproduction in the Ural River, which led to a decrease in the number of offspring and, as a result, a reduction in commercial fish stocks in the region. It was found that in high-water years, even with a low number of producers in spawning grounds, the number of life-resistant sloping juveniles of the studied fish species was greater than in low-water years with a high number of producers. In the course of research, it was found that unfavorable hydrological conditions in the Ural River had a lesser impact on the roach and bream, and the number of juveniles of the latter has increased over the years. Commercially valuable walleye, asp and carp are in a depressed state, the number of recorded juveniles of which was ten times less than bream and roach. The state of reproduction of the carp is alarming, the number of juveniles of which reached a critical level in low-water 2019. According to the results of the study, it is recommended to implement a number of comprehensive measures of fisheries reclamation to improve the state of commercial stocks in the Ural-Caspian region.

Nitrogen use efficiency in marandu Palisadegrass (Urochloa brizantha) during dry seasons in Rio De Janeiro, Brazil

The growing demand for food, coupled with climate change risks, highlights the need to enhance agricultural productivity while reducing environmental impacts. Tropical and subtropical regions, although offering potential for increased production, are highly vulnerable to climate variability. This study evaluated the nitrogen use efficiency (NUE) of Marandu Palisadegrass (Urochloa brizantha, syn. Brachiaria brizantha) under water stress, considering agronomic (biomass production) and environmental parameters (N losses). NUE was assessed using 15 N-labeled fertilizer, and the Nitrogen Nutrition Index (NNI) was tested as a tool for nitrogen management. Climatic conditions significantly influenced NUE and biomass production. For the 100 kg N ha−1 treatment, biomass decreased from 17.51 tons ha−1 in 2020 to 10.38 tons ha−1 in 2021, while nitrogen losses were reduced from 70.48 to 48.29 kg N ha−1. Similarly, for the 50 kg N ha−1 treatment, biomass dropped from 16.08 to 6.94 tons ha−1, and N losses decreased from 21.38 to 15.93 kg N ha−1. These reductions highlight the role of climatic variation, with reduced precipitation and increased temperature fluctuations impacting productivity. The NNI proved effective in monitoring critical nitrogen levels and guiding fertilizer management. These findings support the adoption of proper fertilization practices to enhance NUE, reduce environmental impacts, and aid in the recovery of degraded pastures in tropical and subtropical agroecosystems.