Low Flow Research Articles

Thermal management of water electrolysis using membrane distillation to produce pure water for hydrogen production

When electrolysis units are used for water splitting to provide green hydrogen, waste heat must be dissipated to avoid performance degradation. Therefore, the hypothesis was that if a membrane distillation unit could use the waste heat to desalinate the feed water, then the operating costs may be reduced. This study demonstrated the first integration of a 0.03 m2 active area membrane distillation heat exchanger (MDHX) system with a 2.2 kW commercial electrolyser. The MDHX system satisfied the thermal requirements of the electrolysis unit. It was estimated that for a 2GW electrolysis plant, it could result in annual savings of up to $2 million. During operation with the 2.2 kW electrolyser, the MDHX unit was able to produce 50 % of the permeate rate required to match the water consumption of the electrolyser. Experimentally the MDHX system operated with a specific electrical energy consumption of 230 kWh/m3. Design changes such as improving pump efficiency and optimising flow field geometry to allow for lower flow rates, suggest there is scope for reduction in energy consumption. Indeed, further development of the MDHX technology is necessary before it can compete with large-scale seawater reverse osmosis (SWRO) methods.

Tuft Dynamics and the Reproductive Phenology of Zostera caespitosa on the Southern Coast of Korea

The aim of study is to determine which environmental factors could influence the biological traits of Z. caespitosa, a unique tuft-forming seagrass. This study examined the dynamics of tufts and the growth of Z. caespitosa, along with the environmental factors. The reproductive traits were also examined to estimate the potential importance of sexual reproduction in population persistence. The density of tufts remained constant, and no new tufts produced through seedling recruitment were observed throughout the sampling period. On the other hand, the tuft size and growth exhibited clear seasonal manners and strong correlations with the water temperature, indicating that water temperature regulates the tuft dynamics and growth. The optimal growth temperature for Z. caespitosa at the study site was approximately ~22.5 °C during early summer, with growth severely inhibited during periods of high-water temperatures. Z. caespitosa was characterized by a low flowering percentage and fewer inflorescences, resulting in extremely low potential seed production. Z. caespitosa maintained its populations through clonal tuft growth with low sexual reproduction and restricted growth at high water temperatures. Hence, this seagrass species may be vulnerable to disturbances, exhibiting low resilience and facing a high risk of becoming a threatened species in coastal waters.

The assessment of low flow at El Abid river basin for a good management of water resource (High Atlas/Morocco)

Abstract In a scenario where pressures on aquatic ecosystems and the water demands of communities are on the rise, coupled with the impacts of global changes, understanding low water flows becomes a critical concern. Low flow is characterized as a natural and seasonal phenomenon, typically stemming from varying degrees of prolonged and severe rainfall deficits. This phenomenon is prone to temporal and spatial fluctuations, ultimately causing a reduction in streamflow. The El Abid River Basin is located within the big Oum Er Rbia watershed, covering an area of 30.600 km2. El Abid river stands out as the principal tributary of the Oum Er Rbia, boasting an average annual flow of 32 m3/s−1, with a maximum average flow reaching 77 m3/s−1 and a minimum average flow of 10 m3/s−1. The hydrological regime of this river exhibits a pattern of intermittent and extreme floods, as well as periods of low flow sustained by water from the karst hydrosystems of the central High Atlas. The aim of this study is to characterize the low flow rates within the upstream part of El Abid river basin, intending to enhance the management of water resources in this basin. The methodology employed involves extracting the minimum flows, calculating the severity thresholds for low flow, determining the lowest average monthly flow of the year, computing low flow rates based on monthly flow averages, and calculating low flow values for specific return periods. Monthly discharge data from two hydrometric stations within our study area, namely Ait Ouchéne and Tizi Nisly, were utilized. The dataset spans the period from 1976 to 2018.

The mechanism of proppant transport dynamic propagation in rough fracture for supercritical CO2 fracturing

Supercritical CO2 fracturing technology has shown great potential for enhancing production in unconventional reservoirs. It is essential to clarify the transport mechanism of proppant under the dynamic propagation conditions within rough fractures. A realistic rough fracture model is reconstructed, and Computational Fluid Dynamics simulations are conducted to track proppant movement during fracture propagation. The typical transport characteristics of proppant within rough fractures are revealed, and the effects of fracture propagation rate, proppant density, mass flow rate, particle size, sand ratio, and temperature on the support effect are discussed. The results show that the flow channels formed by sand carrying fluid in rough fractures are complex, with fracture propagation changing some flow channels. The proppant forms an irregular sand bed interspersed with unfilled areas, and complex flow characteristics are generated. The increase in fractal dimension increases the resistance in the fluid flow process and affects the movement of the proppant, which tends to create unfilled areas. Low density and size of proppant can improve the proppant placement length. In a certain temperature range, high temperature injection of sand carrying fluid can improve the proppant placement effect. In addition, the low sand ratio and high mass flow rate pumping can be used to form the dominant channel, followed by pumping with a high sand ratio and low mass flow rate for effective support.

Lower peak expiratory flow rate is associated with a higher risk of pneumonia in patients with stroke.

Low peak expiratory flow (PEF) rate is common in patients with stroke. Studies on changes in PEF rates in patients with stroke often have small sample sizes, limiting the generalizability of their findings. This study aimed to compare the PEF rates between patients who were post-stroke with or without pneumonia and age- and sex-matched healthy controls and explore the PEF-pneumonia association among stroke survivors. Prospective observational study. Department of Rehabilitation, the First Affiliated Hospital of Wenzhou Medical University. Initially, 809 patients with stroke undergoing inpatient rehabilitation were recruited. Data collected included the demographics, stroke history, the presence of dysphagia, and the PEF rates on admission. Logistic regression analysis was conducted to identify the PEF threshold as predictive of pneumonia after adjusting for confounders. Patients with stroke had a mean PEF rate of 243.89±139.38 L/min, significantly lower than that of the normal control group. The PEF rate was significantly lower in the pneumonia group than in the non-pneumonia group (P<0.001). Within the stroke cohort, the PEF rates were lower than the predicted rates (P<0.001). Older age, lower PEF(%),and dysphagia were associated with a higher pneumonia risk post-stroke per stepwise multivariate logistic regression analysis. Furthermore, the combination of these three significant predictors (PEF(%), swallowing function, and age) yielded an area under the curve of 0.857 .Regarding age, the cut-off point of ≥65.5 years was the optimal level to discriminate the presence of pneumonia among patients with stroke. For PEF%,the cut-off point of <60% was the optimal level to discriminate the presence of pneumonia among patients with stroke. For screening dysphagia, the patients with impaired safety only and those with impaired safety and efficacy faced a higher pneumonia risk. Patients with stroke exhibited significantly lower peak expiratory flow rates compared to healthy controls after adjusting for age and sex and when compared to their reference values. Decreased PEF rates were independently associated with pneumonia development during inpatient rehabilitation in post-stroke patients. This study suggests that low PEF rates may predict pneumonia and that the prevention of PEF rate decline may prevent pneumonia development.

Climatic and hydrological variability in the Oued Lakhdar watershed (Central High Atlas, Morocco)

Abstract The results of this study highlighted significant changes in hydroclimatic conditions over the period studied. Annual rainfall shows significant variability, with years such as 1996 characterised by exceptional humidity, while others, such as 2017, stand out for their particularly marked drought. This variation can be quantified using the Rainfall Anomaly Index (RAI), providing crucial information for water resource management. Temperatures also show seasonal fluctuations, oscillating between hot summers and cold winters. In particular, 2017 was exceptionally warm, while 2011 was unusually cold. In terms of river flows, there has been considerable variability, with some years showing high flows (e.g. 2011) and others with very low flows (e.g. 1990). However, the general trend towards an increase in flow from the 2010 onwards is notable (Sgat station). The RCV index, which classifies years according to surplus or deficit, highlights the predominance of deficit years. In addition, the Monthly Flow Coefficient (MFC) allows us to subdivide the hydrological regime into periods of high and low water. These results highlight the importance of monitoring hydro-climatic conditions for effective management of water resources and the implementation of measures to adapt to climate change.

Determination of ecological flow based on probability distributions of annual and monthly flows

ABSTRACT Developing scientifically sound ecological flow is crucial for protecting river ecosystems. However, most of the existing hydrological methods for determining ecological flow make it difficult to consider both inter-annual and intra-annual changes in runoff. To compensate for this shortcoming, this paper proposes an innovative ecological flow determination method based on the probability distributions of annual and monthly flows. Marginal distributions of annual and monthly flows are first fitted, and the Copula function is used to create joint probability distributions of annual and monthly flows. Conditional probabilities for different monthly flow sizes under different annual flow conditions are then calculated based on Bayesian inference. The conditional probabilities are combined with the flow–duration curve-–based method to finalize the ecological flow process considering both intra- and inter-annual runoff changes. A case study was conducted in Jinsha River, China. The results show that the total annual ecological water demand of the Jinsha River is 1.50, 1.25, and 1.04 × 1011 m3 under annual flow scenarios of high, medium, and low flows, respectively, which provide a red line for the development of water resources and hydro-energy resources of the Jinsha River, as well as for the better protection of the natural plant and animal species.

Density effects on the hydrodynamics and mixing at a large confluence with a compound channel tributary

Abstract Confluences are marked by converging streamlines, complex hydrodynamics features and mixing processes. Understanding such intricate flow patterns and their effects on the mixing at natural river junctions is difficult, particularly for large confluences with a compound channel tributary, due to the scarcity of field data. This research aims to assess the effects of density differences on hydrodynamics and mixing at the large river confluence between the Yangtze River and its tributary, the Poyang Lake, whose outflow channel has a large inner-side floodplain. Field data were collected during three surveys under various flow conditions to analyse how the alternate flow mechanism (compound channel vs single channel) of the Poyang Lake outflow channel influences the confluence mixing process. In high flow and relatively high flow conditions, the Poyang Lake outflow channel functioned as a compound channel and switched to a single channel in low flow. Acoustic Doppler current profiling (ADCP) was used in all three surveys to explore the features of hydrodynamics and the mixing process at the confluence, supplemented by water quality sampling to characterise the mixing patterns. Secondary flows observed during the field surveys were found to be affected by alterations in the flow mechanism (compound channel vs single channel) of the Poyang Lake outflow channel and the density effects, which were characterised using the densimetric Froude number Frd. Ultimately, the findings obtained in these field surveys confirm the role of density differences between the tributaries in significantly affecting hydrodynamics features and the mixing process at river confluences.

Comprehensive, Multi‐Scale Evaluation of Field Methods for Assessing Stream–Aquifer Interactions Along Channelised Lowland Streams

ABSTRACTStream–aquifer interactions (SAIs) play a critical role in effective groundwater management, yet their complex dynamics remain poorly understood in channelized lowland perennial streams. This study presents a multi‐scale, multi‐technique investigation of SAIs along two long‐stream reaches in Tennessee, United States. The goal is to define a suitable methodology for characterising SAIs in this specific hydrological setting, serving as a starting point for developing a more standardised and replicable approach. The methodology includes an initial evaluation of various field techniques, followed by extensive surveys using potentiomanometers, electromagnetic induction (EMI), vertical temperature profilers (VTPs) and complementary methods such as seepage meters, bank tests and well‐data analyses. Results reveal distinct hydrogeomorphic behaviours across and along the streams, challenging the SAI‐homogeneity notions typically assumed in groundwater models. Nonconnah Creek exhibited streambed colmation and negligible hydraulic gradients, resulting in disconnection from the aquifer during low flows, except for a 300‐m losing reach with high downward gradients. In contrast, the Loosahatchie River displayed relatively homogeneous streambed properties and small, upward hydraulic gradients, suggesting uniform SAIs along the surveyed reaches. EMI proved highly effective for mapping streambed sediments quickly, while potentiomanometers accurately measured small head differences critical for understanding SAI dynamics. VTPs were less practical due to the extended data‐collection times required and their vulnerability to flooding. This study emphasises the importance of multi‐scale investigations using diverse techniques to accurately characterise SAIs in lowland streams, highlighting the confounding influences of geological formations, anthropogenic alterations and depositional processes on groundwater–surface water interactions. The findings contribute to refining local water balances, informing groundwater management strategies and underscoring the need for incorporating local‐scale field data into regional groundwater models. The proposed methodology serves as a foundation for developing a standardised approach for characterising SAIs in lowland channelized perennial streams, adaptable for similar stream systems worldwide.

Efficiency high-order discontinuous Galerkin method for low speeds flows with time-derivative preconditioning

A local preconditioning high-order discontinuous Galerkin (DG) method is introduced to enhance the efficiency and accuracy of the density-based approach for low-speed flows. The method is based on the time-derivative preconditioning technique typically employed in finite volume methods. Traditional approximation methods that only precondition low-order derivatives lead to incompatibility of the equations. To extend the preconditioning technique to the DG method, we employ an analytic preconditioning mass matrix derived from the DG formulation of the preconditioned Navier–Stokes equations. Modified numerical flux functions and a self-adaptive local velocity truncation parameter are employed for DG systems with preconditioning. We demonstrate the efficiency and accuracy of the preconditioned DG method using explicit and implicit schemes for steady flows and a dual-time scheme for unsteady flows. The method has been implemented and used to compute a variety of flow problems, including inviscid and laminar flows, utilizing various degrees of polynomial approximations. Computations with and without preconditioning are performed to analyze the influence of spatial discretization on the accuracy and convergence of the DG solutions at low Mach numbers. Numerical results underscore the enhanced accuracy and convergence properties of the proposed method for low-speed flows, indicating significant performance improvements over traditional methods.

Eddy viscosity enhanced temporal direct deconvolution model for temporal large-eddy simulation of turbulent channel flow

In this work, a novel eddy viscosity enhanced temporal direct deconvolution model (TDDM) is proposed for temporal large-eddy simulation (TLES) of turbulent channel flow at large filter widths. To improve the accuracy of the constant eddy viscosity (CEV) model, particularly in the near-wall region, a damping function is incorporated to refine its performance. Moreover, a spatial filtering strategy is introduced to reduce the aliasing errors associated with the computation of subfilter-scale (SFS) stress, thereby enhancing numerical stability. In the a posteriori study, the accuracy of the CEV model is assessed comprehensively by comparing the TLES results with corresponding temporally filtered direct numerical simulation data. The results demonstrate that the CEV-enhanced TDDM provides accurate predictions across various statistical properties of velocity, instantaneous flow structures, kinetic energy spectra, and SFS energy fluxes. The coefficient sensitivity analysis of the CEV model reveals that the model coefficient significantly influences low Reynolds number flows, while its impact on high Reynolds number flows is relatively small. TLES on coarse grids demonstrate that the CEV-enhanced TDDM exhibits strong robustness and accuracy at different grid resolutions. Additionally, the CEV-enhanced TDDM in high Reynolds number flows is stable and accurate at remarkably large filter widths.

Comprehensive analysis of emissions from wood and cow dung burning using chemometrics and two-dimensional gas chromatography

Biomass burning is a global source of climate- and health-affecting emissions. The impacts of biomass burning emissions (BBE) are tied to their complex and variable chemical makeup. For instance, the nitrogen content of BBE influences their capacity to absorb light, and therefore affect the Earth's radiative budget. Factors such as temperature, biomass type, or air flow rate during the combustion all modify the composition of BBE, making accurate characterization challenging. Herein, for the first time, principal component analysis (PCA) was applied to emissions gathered during laboratory-based combustion of wood and cow dung biomass in a tube furnace. A thermal desorption two dimensional time-of-flight gas chromatography mass spectrometry (TD-GC × GC-ToF-MS) setup was employed to separate and identify chemical species. By combining these techniques with a feature selection algorithm, we determined that low temperature and air flow rate lead to greater feature separation on PCA scores plots. Of the 729 variables used to construct the plots, 61 were identified as significant. These species - including sugars such as d-Allose and melezitose, as well as tracers such as levoglucosan and guaiacol - significantly differentiated emissions from wood versus cow dung biomass, especially at lower temperatures. In particular, combustion of either fuel at 0.2 slpm and 500 °C, lead to 20 times the variability in levoglucosan peak area over more efficient furnace parameters. Chemical species evolved only from dung burning contained on average 0.595 nitrogen atoms versus 0.515 for wood, indicating that a higher nitrogen content of the base fuel may not necessarily translate into emission of unique nitrogen containing species, potentially causing the underestimation of dung burning impacts. Overall, TD-GC × GC-ToF-MS coupled to PCA reliably separated emissions from wood and dung biomass while simultaneously identifying significant chemical features, displaying the suitability of this combination of techniques towards characterizing complex BBE matrices in the future.

Transport of microplastics treated with dielectric barrier discharge (DBD) plasma in saturated porous media

The performance of discharge plasma in treating organic pollutants and micro-organisms in water is impressive. When discharge plasma is used to treat polluted water containing organic pollutants and microorganisms, the presence of a certain amount of microplastics (MPs) in the water is unavoidable due to the complexity of the components contained in the water and the prevalence of MPs. MPs, as one of the pollutants that are difficult to be degraded by discharge plasma, undergo physical and chemical changes that increase their risk in the environment after treatment. Therefore, it is necessary to understand the fate of MPs after being treated with discharge plasma. In this study, the surface morphology of plastics before and after discharge plasma treatment was observed by scanning electron microscopy (SEM). The plastics after discharge plasma treatment were characterized by Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) to determine the changes in oxygen-containing functional groups on the surface. The recovery of microplastics (MPs) in saturated porous media under different physicochemical and plasma oxidation conditions was investigated by column experiments. It has been shown that MPs exhibit increased recovery under conditions of increased flow rate and pH. A decrease in recovery was observed at elevated ionic strength and co-existing cation valence. High voltages and low air flow rates increase the oxidation of MPs by increasing the thermal effects of the dielectric barrier discharge (DBD) plasma system, the amount of reactive oxygen species (ROS) and the intensity of ultraviolet ray (UV) irradiation. The mobility of MPs is enhanced by a combination of these factors. The advection–dispersion equation (ADE) fits the transport data of MPs well. The interaction energy between quartz sand and MPs was calculated using the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. This study provides a new perspective on the potential risks of discharge plasma in water treatment.

Coordination of energy loss and fish friendliness for a low-head tubular-pump blade based on a multi-objective optimization model

Tubular pumps and turbines are the water-to-electricity conversion devices widely used in pumped hydro storage systems for low heads and high flow rates. An ecological concern is the high proportion of fish injuries caused by the rotating blades. In this study, a tubular pump blade is retrofitted to balance the energy loss and fish friendliness through multi-objective optimization, combining computational fluid dynamics with a mathematical blade strike model. Sensitivity analysis identifies nine geometric variables out of thirteen for optimizing blade design. An approximation model is developed to implement optimization algorithm and achieve the objective function. By artificially assigning weights to targeted performance metrics, three scenarios are obtained: the optimal efficiency scheme (A), the optimal fish friendliness scheme (C) and the balanced scheme (B). Scheme C achieves a fish survival ratio of 100 % at multiple flow rates (for fish lengths of Lf/D=1/12), but results in a 6.4 % decrease in efficiency compared to scheme A. Additionally, a negative blade attack angle can improve flow pattern. Considerable reduction in fish mortality can be obtained by equipping the rotor with a larger size but lower shaft speed, while also limiting the fish size to pass through the pump running at a reduced flow rate.

Turbulent flow field in maglev centrifugal blood pumps of CH-VAD and HeartMate III: secondary flow and its effects on pump performance.

Secondary flow path is one of the crucial aspects during the design of centrifugal blood pumps. Small clearance size increases stress level and blood damage, while large clearance size can improve blood washout and reduce stress level. Nonetheless, large clearance also leads to strong secondary flows, causing further blood damage. Maglev blood pumps rely on magnetic force to achieve rotor suspension and allow more design freedom of clearance size. This study aims to characterize turbulent flow field and secondary flow as well as its effects on the primary flow and pump performance, in two representative commercial maglev blood pumps of CH-VAD and HeartMate III, which feature distinct designs of secondary flow path. The narrow and long secondary flow path of CH-VAD resulted in low secondary flow rates and low disturbance to the primary flow. The flow loss and blood damage potential of the CH-VAD mainly occurred at the secondary flow path, as well as the blade clearances. By contrast, the wide clearances in HeartMate III induced significant disturbance to the primary flow, resulting in large incidence angle, strong secondary flows and high flow loss. At higher flow rates, the incidence angle was even larger, causing larger separation, leading to a significant decrease of efficiency and steeper performance curve compared with CH-VAD. This study shows that maglev bearings do not guarantee good blood compatibility, and more attention should be paid to the influence of secondary flows on pump performance when designing centrifugal blood pumps.

Spatial patterns of high-risk biomechanical metrics in plaques with abnormal vs. normal physiological flow indices

BackgroundPlaques associated with abnormally low physiological flow reserve indices are appropriate for percutaneous coronary intervention (PCI). However, recent trials demonstrate that PCI of ischemia-producing lesions does not reduce major adverse cardiac events (MACE). Low endothelial shear stress (ESS) or high ESS gradient (ESSG) are associated with MACE wherever they occur along the plaque. This study aims to determine the presence of high-risk ESS metrics in obstructive coronary plaques with high-risk (<0.80) vs. borderline-risk (0.80–0.89) vs. normal Instantaneous Wave-free Ratio (iFR) (>0.89). MethodsWe included 50 coronary arteries (50 patients) with variable iFR values who underwent coronary angiography and optical coherence tomography (OCT), followed by 3D reconstruction and computational fluid dynamics calculations of ESS/ESSG. The cohort was divided into 3 groups: iFR < 0.80, iFR 0.80–0.89, and iFR > 0.89. Spatial distribution of ESS metrics was reported along the course of each plaque, and high-risk ESS metrics and their location were compared among the 3 iFR subgroups. ResultsHigh-risk ESS features (Minimal ESS, Maximum ESSG) were similarly distributed along the course of the atherosclerotic plaque in the three iFR subgroups, both in absolute value and in location: Min ESS: 0.5 ± 0.3 vs. 0.4 ± 0.2 vs. 0.4 ± 0.2 Pa respectively (p = 0.60); Max ESSG any direction: 13.7 ± 9.4 vs. 10.4 ± 10.6 vs. 10.0 ± 7.8 Pa/mm respectively (p = 0.30). ESS metrics were spatially located up to ≥18 mm from the plaque minimal luminal area (MLA) in both directions. ConclusionHigh-risk ESS metrics are similarly observed in plaques with normal or abnormal iFR, both in absolute value and spatial location in reference to the MLA. Utilizing iFR to identify plaques likely to cause MACE would miss the majority of plaques mechanistically at high-risk to destabilize and cause future adverse cardiac events.

Hydraulic valve design methodology for hydro turbine control system

The control of the turbine and its equipment in a hydroelectric power plant requires the HPU (hydraulic power unit) to deliver large volumes of working fluid in a short time at specific optimum control parameters. The use of typical proportional flow control valves created by manufacturers of hydraulic components in low-pressure control systems is disadvantageous due to high pressure losses in the control chambers. This paper presents the methodology and test results while designing a hydraulic proportional valve for low pressure and high flow rate operation. CFD (computational fluid dynamics) theory was analyzed and characteristic values were determined. The validation of CFD tests through those on the test bench was carried out, correction factor was determined. A new proprietary solution was developed and a series of simulation studies were carried out to determine the flow characteristics depending on the degree of the opening of the proportional flow control valve.

Genetic diversity and molecular evolution of the internal transcribed spacer regions (ITS1–5.8S-ITS2) of Babesia vogeli

Canine babesiosis, a severe haemoparasitic disease caused by Babesia species, has a significant global presence and can be fatal if left untreated. The current study was aimed to perform the population genetic characterization of B. vogeli on the basis of the internal transcribed spacer regions (ITS1–5.8S-ITS2). A maximum likelihood tree constructed with the Hasegawa-Kishino-Yano model grouped all sequences into a single major clade (BvG1), with the exception of a Taiwanese isolate (EF186914), which branched separately. This Taiwanese isolate represented a novel genotype (BvG2) identified in the present study. Nucleotide sequences (n = 62) exhibited 92.5–100 % nucleotide identity among themselves. However, the BvG1 and BvG2 genotypes shared a lower identity of 92.5–93.8 % between them. Notably, the newly generated Indian sequences (n = 21) demonstrated a high degree of homology, with 98.3–100 % identity. Alignment of the nucleotide sequences revealed 58 variations across the dataset. Additionally, 32 sites exhibited variation within the BvG1 genotype, while 56 sites differed between BvG1 and BvG2 genotypes. Within different B. vogeli populations, the nucleotide diversity (π) was low, but the haplotype diversity (Hd) was high. The haplotype diversity of the Indian population, BvG1 genotype and the combined dataset was ~0.8 suggesting a high haplotype diversity. The median-joining haplotype network displayed a total of 21 haplotypes, out of which six haplotypes consisted of more than one sequence (2–25 sequences). Haplotype distribution showed significant geographical structuring, with most haplotypes confined to a single country. Only two haplotypes (9.52 %; Hap_1 and Hap_4) were shared between countries, whereas 19 haplotypes (90.48 %) were country-specific. Hap_1, Hap_6, and Hap_4 were the most representative haplotypes, comprising 25, 10, and four sequences, respectively. India exhibited the highest number of haplotypes (h = 13) followed by China (h = 4), the United States of America (h = 3), Taiwan and Tunisia (h = 2), and Thailand (h = 1). Both location-wise and genotype-wise median joining haplotype networks clustered the haplotypes in two groups, representing two distinct genotypes (BvG1 and BvG2). The B. vogeli populations between Thailand and Tunisia exhibited the highest genetic differentiation (FST = 0.80) with a low gene flow (Nm = 0.125) between them. Results of AMOVA revealed a higher genetic variation within populations (69.43 %) as compared to the variation between them (30.57 %). Neutrality indices and the mismatch distributions of the Indian population and the overall dataset of B. vogeli indicated a constant population size to population expansion and population expansion, respectively, with the presence of two distinct genotypes. These data provide information about parasite population genetics and highlight the importance of starting a long-term molecular surveillance program. In conclusion, a high genetic diversity along with the presence of two distinct genotypes of B. vogeli were observed on the basis of internal transcribed spacer regions (ITS1–5.8S-ITS2).

Landslides and flood hazard mapping using geomorphological methods in Santa Ana, Costa Rica

This study addresses the critical need for comprehensive hazard maps to guide urban and periurban risk management in Santa Ana, Costa Rica. Located near the capital, San Jose, Santa Ana is a rapidly developing municipality characterized by high-value properties, commercial zones, luxury housing, agricultural, and protected areas. However, it faces significant challenges from landslides and floods. Despite its vulnerability, the municipality lacks detailed, holistic hazard assessments. To bridge this gap, we employed geomorphological methods, including morphometry and morphogenetics, integrated with geographic information systems (GIS), historical data, and on-site validation. Our analysis identified that slopes exceeding 20° are particularly susceptible to landslides, with valleys and unstable hillslopes being critical zones for seismic and water-induced destabilization. For flood hazards, areas with low slope and high flow accumulation, such as alluvial fans and flood plains, were found to be highly susceptible. Field and mapping validation against the DesInventar disaster database confirmed the accuracy of our hazard zones. These findings provide essential geospatial insights for effective risk management, decision-making, and territorial planning, enabling proactive and adaptive responses to natural hazards in Santa Ana. While this study does not present radical methodological innovations, its main contribution lies in demonstrating how easy-access and practical geomorphological tools can be used to generate valuable information on risk zoning in regions with limited resources. Furthermore, the methodology and insights from this study are applicable to other urban and periurban regions facing similar geomorphic hazards, highlighting its broader relevance.

Pelvic congestion syndrome analysis through quantitative 2-dimensional phase-contrast magnetic resonance imaging: A promising vision from an observational cohort study.

To examine the application of quantitative 2-dimensional phase-contrast magnetic resonance imaging (2D PC-MRI) for treating patients with pelvic congestion syndrome (PCS). We conducted a retrospective cross-sectional analysis by using quantitative 2D PC-MRI data enrolled between April 2017 and Sep 2023. In addition, 32 healthy female controls (HCs) were included. Most patients with PCS presented with chronic pelvic pain and more than half had extra-pelvic venous symptoms (80/81, 98% and 45/81, 56%, respectively). Quantitative 2D PC-MRI analyzed the 81 patients with PCS, 239 patients without PCS, and 32 HCs. The patients with PCS had higher stroke volume (SV), absolute SV (ASV), and mean flux (MF) in the calf region (interstitial pixel shift) than did the HCs. In the left gonadal vein, the patients with PCS had higher SV, backward flow volume (BFV), ASV, and MF and lower forward flow volume (FFV), stroke distance (SD), and mean velocity (MV) than did the HCs. However, the patients with PCS had lower SV, FFV, MF, SD, and MV in the great saphenous veins. Quantitative 2D PC-MRI analysis revealed that the PCS group had higher SV, FFV, BFV, ASV, and MF in the calf region than did the non-PCS group. The variables that most strongly differentiated the patients with PCS from the HCs were SV in the great saphenous veins, SD in the great saphenous veins and left gonadal vein, and MV in the great saphenous veins and left gonadal vein. Caudal flow in the left gonadal vein was identified in half of the patients with PCS (39/81, 48.1%); 14 of them received embolization for left gonadal vein. In additional to providing an objective 3-dimensional morphology of the pelvic veins and extra-pelvic leaks, quantitative 2D PC-MRI analysis reveals distinct hemodynamic profiles between patients with PCS, those without PCS, and HCs, especially in the gonadal veins and regional perfusion of the calves.