Search Results (789)

This study applies Computational Fluid Dynamics (CFD) and mathematical modeling to examine uterine and umbilical arterial blood flow during pregnancy, providing a more detailed understanding of hemodynamic changes across gestation. Statistical analysis of Doppler ultrasound data from a large cohort of more than 200 pregnant women (in the second and third trimesters) reveals significant increases in the umbilical arterial peak systolic velocity ($PSV$) between the 22nd and 30th weeks, while uterine artery velocities remain relatively stable, suggesting adaptations in vascular resistance during pregnancy. By combining the Navier–Stokes equations with Doppler ultrasound-derived inlet velocity profiles, we quantify several key fluid dynamics parameters, including time-averaged wall shear stress ($TAWSS$), oscillatory shear index ($OSI$), relative residence time ($RRT$), Reynolds number ($Re$), and Dean number ($De$), evaluating laminar flow stability in the uterine artery and secondary flow patterns in the umbilical artery. Since blood exhibits shear-dependent viscosity and complex rheological behavior, modeling it as a non-Newtonian fluid is essential to accurately capture pulsatile flow dynamics and wall shear stresses in these vessels. Unlike conventional imaging techniques, CFD offers enhanced visualization of blood flow characteristics such as streamlines, velocity distributions, and instantaneous particle motion, providing insights that are not easily captured by Doppler ultrasound alone. Specifically, CFD reveals secondary flow patterns in the umbilical artery, which interact with the primary flow, a phenomenon that is challenging to observe with ultrasound. These findings refine existing hemodynamic models, provide population-specific reference values for clinical assessments, and improve our understanding of the relationship between umbilical arterial flow dynamics and fetal growth restriction, with important implications for maternal and fetal health monitoring. Full article

The role of on-site wastewater treatment (OSWT) is increasingly important for water reuse and local sustainability, but treatment efficiency is highly dependent on hydraulic behavior and mixing. This study used validated CFD simulations and tracer experiments to analyze flow patterns and mixing performance in a six-zone OSWT unit under different operational scenarios, including inflow, aeration, recirculation, combined mechanisms, and closed-loop operation without inflow. The results show that influent flow is essential for maintaining convective transport and system-wide momentum, while aeration and recirculation enhance local mixing, but cannot fully overcome geometric dead zones. The combined use of inflow, aeration, and recirculation achieved the highest mixing efficiency and minimized the dead volume, whereas scenarios lacking inflow exhibited severe stagnation and expanded dead zones. These findings highlight the need to integrate hydraulic interventions with thoughtful reactor design to ensure effective and resilient small-scale wastewater treatment systems. Full article

Risk zone delineation and mobility behavior control constitute critical measures in pandemic containment. Numerous studies utilize static demographic data or dynamic mobility data to calculate the high–risk zones present in cities; however, these studies fail to concurrently consider activity and mobility patterns of populations in both space and time, which results in many studies only being able to employ static geostatistical analytical methods, neglecting the transmission risks associated with human mobility. This study utilized the mobile phone signaling data of Shenzhen residents from 2019 to 2020 and developed a CP tensor decomposition algorithm to decompose the long-sequence spatiotemporal trajectory data to detect high risk zones in terms of detecting overlapped community structures. Tensor decomposition algorithms revealed community structures in 2020 and the overlapping regions among these communities. Based on the overlap in spatial distribution and the similarity in temporal rhythms of these communities, we identified regions with spatiotemporal co-location as high–risk zones. Furthermore, we calculated the degree of population mixing in these areas to indicate the level of risk. These areas could potentially lead to rapid virus spread across communities. The research findings address the shortcomings of currently used static geographic statistical methods in delineating risk zones, and emphasize the critical importance of integrating spatial and temporal dimensions within behavioral big data analytics. Future research should consider utilizing non-aggregated individual trajectories to construct tensors, enabling the inclusion of individual and environmental attributes. Full article

Background/Objectives: In the twin-screw wet granulation (TSWG) process, accurate measurement of residence time distribution (RTD) is critical, as it characterizes material transport kinetics and mixing behavior. It plays a critical role in evaluating the homogeneity and stability of the granulation process and optimizing process parameters. It is necessary to overcome the limitations arising from the complex and time-consuming procedures of conventional RTD determination methods. Methods: This study proposes a new RTD detection method based on image processing. It uses black dye as a tracer to obtain RTD curve data, and the effects of process parameters such as tracer dosage, screw speed, and feeding rate on the RTD were investigated. Results: The results show that the established method can accurately determine RTD and that the tracer dosage has no significant effect on the detection results. Further analysis revealed that the screw speed is negatively correlated with the mean residence time (MRT). As the speed increases, not only does the MRT shorten, but its distribution also decreases. Similarly, an increase in the feeding rate also leads to a decrease in the MRT and distribution, but it is worth noting that lower feeding rates are beneficial for achieving a state close to mixed flow, while excessively high feeding rates are not conducive to sufficient mixing of materials in the extruder. Conclusions: The RTD detection method provides a reliable parameter basis and theoretical guidance for the in-depth study of the TSWG process and the development of quality control strategies. Full article

Plastic pollution in marine environments is a globally recognized concern that poses ecological and economic threats. While 80% of plastic originates from land, 20% comes from sea-based sources like shipping and fishing. Comprehensive assessments of fishing-related plastics are limited but crucial for mitigation. This study analyzed the distribution and temporal evolution of three fishing-related items (EPS fish boxes, fragments, and buoys) along the Bocassette spit in the northern Adriatic Sea, a region with high fishing and aquaculture activity. UAV monitoring (November 2019, June/October 2020) and structured interviews with Po Delta fishermen were conducted. The collected debris was mainly EPS, with boxes (54.8%) and fragments (39.6%). Fishermen showed strong awareness of degradation, identifying plastic as the primary litter type and reporting gear loss. Litter concentrated in active dunes and the southern sector indicates human and riverine influence. Persistent items (61%) at higher elevations suggest longer residence times. Mapped EPS boxes could generate billions of micro-particles (e.g., ~10¹³). The results reveal a complex interaction between natural processes and human activities in litter distribution. This highlights the need for integrated management strategies, like improved waste management, targeted cleanup, and community involvement, to reduce long-term impacts on vulnerable coastal ecosystems. Full article

Timber and other biobased materials store carbon that has been captured from the atmosphere during photosynthesis and plant growth. The estimation of these biogenic carbon stocks in the harvested wood products (HWP) pool has received increasing attention since its inclusion in greenhouse gas reporting by the IPCC. It is of particular interest for long service life products such as timber in buildings; however, some aspects require further thought—in particular the handling of service lives as opposed to half-lives. The most commonly used model for calculating changes in the HWP pool uses first order decay based on half-lives. However other approaches are based on average service lives and estimates of residence times in the product pool, enabling different mathematical functions to be used. This paper considers the evolution of the two concepts and draws together data from a wide range of sources to consider service life estimation, which can be either related to design life or practical observations such as local environmental conditions, decay risk or consumer behaviour. As an increasing number of methods emerge for calculating HWP pool dynamics, it is timely to consider how these numerical inputs from disparate sources vary in their assumptions, calculation types, accuracy and results. Two groups are considered: half-lives for first order decay models, and service life and residence time population distributions within models based on other functions. A selection of examples are drawn from the literature to highlight emerging trends and discuss numerical constraints, data availability and areas for further study. The review indicated that issues exist with inconsistent use of nomenclature for half-life, average service life and peak flow from the pool. To ensure better sharing of data between studies, greater clarity in reporting function types used is required. Full article

We propose a new unit distribution, study its properties, and provide an important application in the field of geology through a set of risk indicators. We test its practicality through two applications to real data, make comparisons with the well-known beta and Kumaraswamy distributions, and estimate the parameters of the new distribution in different ways. We provide a new regression model and apply it in statistical prediction operations for residence times data. Full article

Stream metabolism is traditionally defined as the combined metabolism of all aerobic organisms in a stream. Its component processes of oxygenic photosynthesis and aerobic respiration create and consume dissolved oxygen (DO) and therefore can be measured using time series of DO concentration, solar radiation, and water temperature, in conjunction with a model of DO dynamics that includes photosynthesis, respiration, and oxygen exchange with the atmosphere. A complication is that stream communities typically exhibit pronounced longitudinal heterogeneity in habitat type (e.g., shaded versus unshaded reaches) and species composition and abundance. The influence of a given stream reach and associated community on DO concentration propagates downstream with the current, gradually being replaced, over a transition zone, by the influence of the next downstream reach. Knowing the approximate length of this transition zone is important when estimating stream metabolism with one-station DO monitoring, since it indicates which stream reach and associated community the metabolism estimates apply to. We propose new methods for estimating the transition-zone length and for estimating the proportions of DO at a given location in a stream reach that entered the reach from upstream, from photosynthesis within the reach, and from atmospheric uptake within the reach. We also propose methods for estimating the residence-time distribution of DO present at a given stream location, and the corresponding distribution of upstream distances at which the DO entered the stream. Both distributions are approximately exponential. Thus, habitat immediately upstream of the sonde has the greatest influence on metabolism estimates with one-station monitoring, and it is therefore important to place the sonde so this habitat is representative of the study reach. Full article

A lack of access to healthy food has been a problem for low-income residents in many developed urban areas. Due to travel time and additional transportation costs, these residents often opt for unhealthy food rather than nutritious alternatives. This study examines the spatial distribution of food deserts in Mississauga—one of Canada’s most populous cities and a city with one of the highest diabetes rates in the Province of Ontario. Network analysis was employed to map the geographic inaccessibility to essential nutritious food, defined as residential areas that are beyond a 15-min walking distance from grocery stores. Socioeconomic indicators were integrated to identify and compare the regions that are socioeconomically disadvantaged and, therefore, most affected by food inaccessibility. The results reveal the presence of several food deserts spatially dispersed in Mississauga. The implications of these findings are discussed, with a focus on the relationship between food desert locations and the socioeconomic conditions of the affected residents. This study provides a practical, replicable approach for identifying food deserts that can be easily applied in other regions. The model developed offers valuable tools for policymakers and urban planners to address food desert issues, improving access to healthy food and positively impacting the health and well-being of affected populations. Full article

Large-scale bioprocesses often suffer from spatial heterogeneities, which impact microbial performance and often lead to phenotypic population heterogeneity. To better understand these effects at the single-cell level, this study applied, for the first time, automated real-time flow cytometry (ART-FCM) to monitor L-phenylalanine production with an Escherichia coli triple reporter strain in a fed-batch process with glycerol as the carbon source. The strain was cultivated in both a well-mixed stirred-tank bioreactor (STR) and a scale-down two-compartment bioreactor (TCB), consisting of an STR and a coiled flow inverter (CFI) in bypass, to simulate spatial heterogeneities. ART-FCM enabled autonomous, high-frequency sampling every 20 min, allowing for real-time tracking of fluorescence signals linked to growth (rrnB-mEmerald), oxygen availability (narGHIJ-CyOFP1), and product formation (aroFBL-mCardinal2). The STR exhibited uniform reporter expression and higher biomass accumulation, while the TCB showed delayed product formation and pronounced phenotypic diversification depending on the set mean residence time in the CFI. Single-cell fluorescence distributions revealed that the shorter mean residence time in the CFI resulted in pronounced subpopulation formation, whereas longer exposure attenuated heterogeneity, indicating transcriptional adaptation. This finding highlights a critical aspect of scale-down studies: increased exposure duration to perturbations can enhance population robustness. Overall, this study demonstrates the relevance of ART-FCM, in combination with a multi-reporter strain, as a pioneering tool for capturing dynamic cellular behavior and correlating it to process performance, providing deeper insights into microbial heterogeneity under fluctuating bioprocess conditions. Full article

Understanding individual movement patterns in stream-resident salmonids is critical for conservation and river management, particularly in Mediterranean streams characterized by high environmental variability. We tagged 997 Mediterranean brown trout (Salmo trutta complex) and conducted an 11-month mark–recapture study using Passive Integrated Transponder (PIT) technology to assess movement behavior in the Flamisell River (Ebro Basin, northeastern Iberian Peninsula). Movements followed a leptokurtic distribution, with 81.8% of the individuals classified as sedentary (median movement = 24.9 m) and 18.2% as mobile (median movement = 376.2 m). Generalized linear models revealed distinct drivers of fish movement for each group. In sedentary trout, movement was mainly influenced by mesohabitat type, season, sex, and body size, with males and larger individuals moving farther. In mobile trout, mesohabitat type, density, and body size were key predictors. Movement patterns were repeatable over time, indicating consistent behavioral tendencies. These results support a bimodal movement strategy and highlight the importance of individual variation. Conservation planning should account for both sedentary and mobile groups to preserve functional and genetic connectivity and improve resilience of Mediterranean streams. Full article

Background and Aim: Pneumococcal pneumonia is a major cause of death globally, emphasizing the importance of vaccination, especially in low- and middle-income countries. In Iran, the 13-valent pneumococcal conjugate vaccine (PCV13) is available exclusively through private healthcare systems, resulting in a lack of studies on the prevalence of Streptococcus pneumoniae (S. pneumoniae) serotypes among vaccinated children. This research aimed to explore and compare the prevalence of nasopharyngeal pneumococcal carriage, serotype distribution, and antibiotic resistance patterns in healthy PCV13-vaccinated and -unvaccinated children. Methods: From August 2023 to November 2024, a multi-center, cross-sectional observational study was conducted in Tehran, Iran. This study included 204 nasopharyngeal samples collected from children aged from 18 to 59 months, involving both cases of children vaccinated with PCV13 and unvaccinated populations. S. pneumoniae was identified through a combination of culture methods and biochemical tests, confirmed by real-time PCR. Serotyping was achieved using cpsB sequencing, and the minimum inhibitory concentration method was employed to assess antibiotic resistance. Results: This study revealed similar S. pneumoniae carriage rates between PCV13-vaccinated and -unvaccinated Iranian children (20.6% vs. 21.6%). Serotypes 23F and 19F were prevalent in unvaccinated children, while 15B/15C was more prevalent in PCV13-vaccinated children. The included S. pneumoniae serotypes in PCV13 were detected more in the unvaccinated group. PCV13-vaccinated children exhibited no penicillin-resistant pneumococcal isolates, although four isolates were non-susceptible in unvaccinated children. Both groups showed substantial resistance to erythromycin and SXT. Previous respiratory infections, daycare attendance, residence in Tehran, and a history of antibiotic consumption increased the risk of pneumococcal carriage. Conclusions: PCV13 vaccination influences pneumococcal serotype distribution and antimicrobial susceptibility, although there was no significant difference regarding carriage rates between vaccinated and unvaccinated groups. These findings highlight the critical importance of vaccination in reducing invasive serotypes and antimicrobial resistance in children under five years old, emphasizing the importance of national PCV vaccination programs alongside continuous serotype surveillance. Full article

Land use composition, water level fluctuations (WLFs), and biogeographical factors are recognized as key drivers of phytoplankton dynamics in reservoir ecosystems. This two-year study presents the first assessment of the combined effects of catchment land use, WLFs, and geographical distance on phytoplankton biomass and community composition across twelve Mediterranean reservoirs in Cyprus, which serve primarily for drinking water supply and irrigation. The results show that higher phytoplankton biomass was recorded in reservoirs whose catchments had >30% coverage by developed land (urban and agricultural), suggesting that increased anthropogenic pressures may lead to nutrient enrichment and elevated productivity. However, despite elevated biomass, no consistent spatial patterns were observed in phytoplankton community composition. The geographical distance between reservoirs had only a minor effect on species distribution, implying that other factors—such as water residence time or hydrological variability—play a more prominent role in shaping community structure. Phytoplankton biomass maxima were most often recorded during periods of elevated water levels and were typically dominated by Chlorophyta, Dinoflagellata, Bacillariophyta, and Charophyta. The pronounced temporal variability in species composition across all reservoirs points to a highly dynamic system, where environmental fluctuations strongly influence community assembly. This study provides the first comprehensive data on phytoplankton in Cyprus reservoirs, highlighting the importance of land use and hydrological regulation for water quality management in similar settings. Importantly, this baseline dataset can support the implementation of the Water Framework Directive (WFD) by contributing to the definition of ecological status classes, establishing reference conditions, and guiding future monitoring and assessment efforts. Expanding such datasets through coordinated, basin-wide monitoring initiatives is essential to improve our understanding of phytoplankton dynamics and their role in ecosystem functioning under the pressures of climate change and intensified land use in this Mediterranean “hot spot”. Full article

This research study proposes an indoor temperature regulation predictive optimal control system that entails the use of both deep reinforcement learning and the Modbus TCP communication protocol. The designed architecture comprises distributed sub-parts, namely, distributed room-level units as well as a centralized main-part AI controller for maximizing efficient HVAC management in single-family residences as well as small-sized buildings. The system utilizes an LSTM model for forecasting temperature trends as well as an optimized control action using an envisaged DQN with predicted states, sensors, as well as user preferences. InfluxDB is utilized for gathering real-time environmental data such as temperature and humidity, as well as consumed power, and storing it. The AI controller processes these data to infer control commands for energy efficiency as well as thermal comfort. Experimentation on an NVIDIA Jetson Orin Nano as well as on a Raspberry Pi 4 proved the efficacy of the system, utilizing 8761 data points gathered hourly over 2023 in Cheonan, Korea. An added hysteresis-based mechanism for controlling power was incorporated to limit device wear resulting from repeated switching. Results indicate that the AI-based control system closely maintains target temperature setpoints with negligible deviations, affirming that it is a scalable, cost-efficient solution for intelligent climate management in buildings. Full article

Background/Objectives: Jaspine B, a synthetic analog of anhydrophytosphingosine, demonstrates significant anticancer activity; however, its clinical application is hindered by its poor oral bioavailability, resulting in suboptimal systemic exposure. This study aimed to enhance the pharmacokinetic properties of Jaspine B by developing a liposomal delivery system. Methods: Jaspine B-loaded liposomes were formulated using a microfluidic approach and characterized by transmission electron microscopy (TEM) to assess particle morphology and size distribution. A sensitive and selective LC-MS/MS assay was developed and fully validated to quantify Jaspine B in rat plasma. The assay revealed excellent linearity across a broad concentration range and high intra- and inter-day precision. A pharmacokinetic study was conducted in Sprague Dawley rats to evaluate the influence of liposomal encapsulation on the pharmacokinetic profile of Jaspine B. Results: The liposomal formulation accelerated the absorption of Jaspine B, reaching the maximum concentration (T_max) at 2 h as opposed to 6 h in plain Jaspine B. The half-life (t_1/2) increased significantly from 7.9 ± 2.3 h to 26.7 ± 7.3 h. The area under the curve (AUC_0–∞) increased over two-fold from 56.8 ± 12.3 ng.h/mL to 139.7 ± 27.2 ng.h/mL, suggesting increased systemic drug exposure. Similarly, the drug molecule’s mean residence time (MRT) increased over three-fold. Conclusions: These results indicate that liposomal formulation enhances the pharmacokinetics of Jaspine B, prolonging its body circulation and exposure, which explains the improved therapeutic outcomes we observed in our previous pharmacodynamic study. Full article