Marine debris is responsible for major problems in our oceans, causing serious environmental degradation, detrimental health effects and economic losses in sectors related to the marine environment. In this work, we examine how plastics released by the Ulla river at the estuary's extreme affect the transport, accumulation, and beaching of floating particles in the R & iacute;a de Arousa, an estuary on the northwest coast of the Iberian Peninsula, as a result of wind force. Using Lagrangian simulations of particle tracking under different wind drag coefficients (1 %, 3 % and 5 %), we evaluate the spatial and seasonal patterns of particle concentration, residence time and deposition on the coast. Our results show that wind plays a crucial role in modulating particle behavior. Low wind-driven conditions favor greater near-shore accumulation and longer residence times, especially in the northern and inner regions of the estuary. As wind influence increases, particle dispersion intensifies, leading to lower overall accumulation and weakening of correlations between river discharge and coastal deposition. Seasonal differences are also studied, with higher concentrations observed in the north during winter and in the south during summer.

BACKGROUND:High-field magnetic resonance imaging (MRI) is a powerful diagnostic tool but can induce unintended physiological effects, such as nystagmus and dizziness, potentially compromising the comfort and safety of individuals undergoing imaging. These effects likely result from the Lorentz force, which arises from the interaction between the MRI's static magnetic field and electrical currents in the inner ear. Yet, the Lorentz force hypothesis fails to explain observed eye movement patterns in healthy adults fully. This study explores these effects and tests whether the Lorentz force hypothesis adequately explains magnetic vestibular stimulation. METHODS:We developed a mathematical model integrating computational fluid dynamics, fluid-structure interaction solvers, and magnetohydrodynamic equations to simulate the biomechanical response of the cristae ampullares. Using high-resolution micro-CT data of the human membranous labyrinth, we ensured anatomical accuracy. Experimental validation involved measuring horizontal, vertical, and torsional slow-phase eye movements in healthy subjects exposed to varying magnetic field intensities and head positions. RESULTS:Our model accurately replicates observed nystagmus patterns, predicting slow-phase eye velocities that match experimental data. Results indicate that Lorentz force-induced stimulation of individual cupulae explains variability in eye movements across different magnetic field intensities and head orientations. CONCLUSIONS:This study empirically supports the Lorentz force hypothesis as a valid explanation for magnetic vestibular stimulation, offering new insights into the effects of high-field MRI on the vestibular system. These findings provide a foundation for future research and improved clinical practices.

BackgroundBenign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo, often effectively treated with standard canalith repositioning maneuvers (CRMs). However, approximately 12.5% of cases remain refractory, leading to persistent symptoms and increased healthcare burden. Variations in the anatomical orientation of the semicircular canals (SCCs) may explain the resistance to conventional maneuvers. This study explores a personalized medicine approach, utilizing computational fluid dynamics (CFD) based on MRI reconstructions to tailor CRMs with the help of mechanical rotation chair according to individual inner ear anatomy.MethodsWe conducted a randomized, multicenter, open-label study targeting patients with refractory posterior canal BPPV. Participants were allocated to either a control group (receiving repeated standard CRMs and Brandt-Daroff exercises) or an intervention group (receiving personalized CRMs based on CFD simulations derived from MRI scans). The intervention group’s maneuvers were executed using a mechanical rotational chair designed for precise angulation. Primary outcomes included resolution of nystagmus and vertigo symptoms, while secondary outcomes measured the reduction in healthcare visits and improved quality of life (Dizziness Handicap Inventory score).DiscussionPersonalized CRMs based on CFD models may enhance treatment efficacy for refractory BPPV by optimizing maneuver angles according to the specific SCC orientation. This approach could significantly reduce symptom persistence, decrease the need for repeated healthcare visits, and improve patient outcomes. The use of non-invasive MRI and CFD techniques represents a novel step toward individualized treatment in vestibular disorders, with potential for broader application in personalized otoneurology. Further analysis will determine the extent of clinical benefit and cost-effectiveness of this approach.Clinical trial registrationClinicalTrials.gov, Identifier: NCT06725966.

Marine plastic litter is an emerging global problem with serious environmental and economic consequences. Once deposited in the ocean, it is transported by currents for long periods of time, making it a transboundary problem. The variety of plastic items makes the study of their transport in the ocean system a challenge. Identifying the sources and analyzing the extent of their dispersion/accumulation can help solve the problem on a global scale. In this study, using modeling tools, the dispersion of particles from land-based sources located on the Spanish Atlantic coast was analyzed over a seven-year period. The results show that the highest concentrations of plastic are found near the coast. The particle dispersion is consistent with the oceanic dynamics of each region studied. The seasonal behavior of plastics arriving in neighboring countries was also analyzed. The time-varying patterns are consistent with local hydrodynamics and the general circulation of the ocean.

Plastic fragmentation alters the size distribution of plastic waste in aquatic habitats, which is accelerated by mechanical stress and weathering degradation processes. Microplastic pieces constitute the vast bulk of plastic pollution in terms of quantity. Their size distribution has been shown to follow a power-law for larger fragments. This work introduces a novel model inspired by raindrop formation, incorporating local oceanographic processes and fragment size, aiming to improve the understanding and prediction of plastic fragmentation in marine environments. Particles can fragment when they reach a certain size, or when shear forces become too strong. Plastic aging’s effect on size distribution is also investigated.

OBJECTIVES:Canalith repositioning procedures to treat benign paroxysmal positional vertigo are often applied following standardized criteria, without considering the possible anatomical singularities of the membranous labyrinth for each individual. As a result, certain patients may become refractory to the treatment due to significant deviations from the ideal membranous labyrinth, that was considered when the maneuvers were designed. This study aims to understand the dynamics of the endolymphatic fluid and otoconia, within the membranous labyrinth geometry, which may contribute to the ineffectiveness of the Epley maneuver. Simultaneously, the study seeks to explore methods to avoid or reduce treatment failure.DESIGN:We conducted a study on the Epley maneuver using numerical simulations based on a three-dimensional medical image reconstruction of the human left membranous labyrinth. A high-quality micro-computed tomography of a human temporal bone specimen was utilized for the image reconstruction, and a mathematical model for the endolymphatic fluid was developed and coupled with a spherical particle model representing otoconia inside the fluid. This allowed us to measure the position and time of each particle throughout all the steps of the maneuver, using equations that describe the physics behind benign paroxysmal positional vertigo.RESULTS:Numerical simulations of the standard Epley maneuver applied to this membranous labyrinth model yielded unsatisfactory results, as otoconia do not reach the frontside of the utricle, which in this study is used as the measure of success. The resting times between subsequent steps indicated that longer intervals are required for smaller otoconia. Using different angles of rotation can prevent otoconia from entering the superior semicircular canal or the posterior ampulla. Steps 3, 4, and 5 exhibited a heightened susceptibility to failure, as otoconia could be accidentally displaced into these regions.CONCLUSIONS:We demonstrate that modifying the Epley maneuver based on the numerical results obtained in the membranous labyrinth of the human specimen under study can have a significant effect on the success or failure of the treatment. The use of numerical simulations appears to be a useful tool for future canalith repositioning procedures that aim to personalize the treatment by modifying the rotation planes currently defined as the standard criteria.

Background and objective: Fractional Flow Reserve (FFR) is generally considered the gold standard in hemodynamics to assess the impact of a stenosis on the blood flow. The standard procedure to measure involves the displacement of a pressure guide along the circulatory system until it is placed next to the lesion to be analyzed. The main objective of the present study is to analyze the influence of the pressure guide on the invasive FFR measurements and its implications in clinical practice. Methods: We studied the influence of pressure wires on the measurement of Fractional Flow Reserve (FFR) through a combination of Computational Fluid Dynamics (CFD) simulations using 45 clinical patient data with 58 lesions and ideal geometries. The analysis is conducted considering patients that were subjected to a computer tomography and also have direct measurements using a pressure guide. Influence of the stenosis severity, degree of occlusion and blood viscosity has also been studied. Results: The influence of pressure wires specifically affects severe stenosis with a lumen diameter reduction of 50 % or greater. This type of stenosis leads to reduced hyperemic flow and increased coronary pressure drop. Thus, we identified that the placement of wires during FFR measurements results in partial obstruction of the coronary artery lumen, leading to increased pressure drop and subsequent reduction in blood flow. The severity of low FFR values associated with severe stenosis may be prone to overestimation when compared to stenosis without severe narrowing. These results have practical implications, particularly in the interpretation of lesions falling within the "gray zone" (0,75-0,80). Conclusions: The pressure wire's presence significantly alters the flow on severe lesions, which has an impact on the FFR calculation. In contrast, the impact of the pressure wire appears to be reduced when the FFR is larger than 0.8. The findings provide critical information for physicians, emphasizing the need for cautious interpretation of FFR values, particularly in severe stenosis. It also offers insights into improving the correlation between FFRct models and invasive measurements by incorporating the influence of pressure wires.

Recent results demonstrated that the use of AI to perform complicated segmentation of medical images becomes very useful when the coronary arteries are considered. Nevertheless, the different segments of the coronary arteries (distal, middle and proximal) exhibit singularities, mostly linked to section changes and image visibility, that point in the direction to consider each in a singular way. In the present contribution we thoroughly analyse the quality of the segmentation obtained using different neural networks, based on the UNet architecture, applied to the three segments of the coronary arteries. We observe that for proximal segments any of the AI considered provides acceptable segmentations while for distal segments the 3D UNet is not able to recognise the coronary structures. In addition, in the distal region there is a noticeable improvement in the 2D UNet without pre-training compared to the 2D networks with pre-training.

Computed tomography of coronary arteries (CTCA) is emerging as the gold standard in the initial evaluation of chest pain. The aim of this study is to calculate the diagnostic performance and clinical usefulness of numerical models of arterial channels flow to assess non-invasive coronary fractional flow reserve by computed tomography (FFRct) compared to assessment by invasive angiography (FFR). Computation of FFR from CTCA images was performed on 39 vessels in 32 patients who followed the usual clinical protocol including invasive coronary angiography and FFR following the usual clinical protocol. From the segmentation of the CTCA images, 3D geometry is obtained, and computational fluid dynamics techniques are applied to accurately reproduce the circulation of blood considering steady and unsteady circulatory conditions. Additional parameters as wall shear stress, stenosis resistance index and ΔFFRct were also calculated. The results obtained show a good correlation between FFRct and invasive FFR, without obtaining false positives values. In addition, no differences were observed between the simulations considering steady conditions or those considering the transient. Additional parameters as wall shear stress, stenosis resistance, and ΔFFRct also showed a good correlation with the invasive values. This new model for calculating the FFRct from non-invasive 3D medical images of coronary tree has shown good agreement with those obtained using invasive techniques. Parameters as wall shear stress, stenosis resistance and ΔFFRct provide useful information that could be helpful in medical decision-making in those situations with FFR values close to the cut-off zone. La tomografía computarizada de arterias coronarias (TCAC) se perfila como el estándar de oro en la evaluación inicial del dolor torácico. El objetivo de este estudio es evaluar el rendimiento diagnóstico y la utilidad clínica de los modelos numéricos de flujo de los canales arteriales para evaluar la reserva fraccional de flujo coronario no invasiva, mediante tomografía computarizada (FFRtc) en comparación con la evaluación mediante angiografía invasiva (FFR). Se realizó el cálculo de FFR a partir de imágenes de TCAC en 39 vasos de 32 pacientes que siguieron el protocolo clínico habitual, incluida la angiografía coronaria invasiva y la FFR. A partir de la segmentación de las imágenes TCAC, se obtuvo la geometría 3D y se aplicaron técnicas de dinámica de fluidos computacional para reproducir con precisión la circulación de la sangre, considerando condiciones circulatorias estables e inestables. También se calcularon parámetros adicionales como la tensión de cizallamiento de la pared, el índice de resistencia a la estenosis y el ΔFFRtc. Los resultados obtenidos muestran una buena correlación entre la FFRtc y la FFR invasiva, sin obtenerse falsos positivos. Además, no se observaron diferencias entre las simulaciones considerando condiciones estacionarias o las que consideraron transitorias. Parámetros adicionales como la tensión de cizallamiento de la pared, el índice de resistencia a la estenosis y el ΔFFRtc también mostraron una buena correlación con los valores invasivos. Este nuevo modelo para el cálculo de la FFRtc a partir de imágenes médicas 3D no invasivas del árbol coronario ha mostrado una buena concordancia con las obtenidas mediante técnicas invasivas. Parámetros como la tensión de cizallamiento de la pared, el índice de resistencia a la estenosis y ΔFFRtc brindan información útil que podría ayudar en la toma de decisiones médicas en aquellas situaciones con valores de la FFR cercanos a la zona de corte.

The Head Impulse Test, the most widely accept test to assess the vestibular function, comprises rotations of the head based on idealized orientations of the semicircular canals, instead of their individual arrangement specific for each patient. In this study, we show how computational modelling can help personalize the diagnosis of vestibular diseases. Based on a micro-computed tomography reconstruction of the human membranous labyrinth and their simulation using Computational Fluid Dynamics and Fluid-Solid Interaction techniques, we evaluated the stimulus experienced by the six cristae ampullaris under different rotational conditions mimicking the Head Impulse Test. The results show that the maximum stimulation of the crista ampullaris occurs for directions of rotation that are more aligned with the orientation of the cupulae (average deviation from alignment of 4.7°, 9.8°, and 19.4° for the horizontal, posterior, and superior maxima, respectively) than with the planes of the semicircular canals (average deviation from alignment of 32.4°, 70.5°, and 67.8° for the horizontal, posterior, and superior maxima, respectively). A plausible explanation is that when rotations are applied with respect to the center of the head, the inertial forces acting directly over the cupula become dominant over the endolymphatic fluid forces generated in the semicircular canals. Our results indicate that it is necessary to consider cupulae orientation to ensure optimal conditions for testing the vestibular function.

Actualmente la ciencias ambientales, y mas concretamente los temas relacionados con la meteorologia y climatologia se han convertido en un area muy solicitada por el alumnado universitario. Por otra parte, la trascendencia y actualidad de temas tan controvertidos y complejos como el cambio climatico atrae tambien a sectores importantes de la sociedad sensibilizados con estos problemas. El clima influye de manera decisiva en la vida de la Tierra y ha condicionado indudablemente el devenir del ser humano desde el principio de los tiempos. La atmosfera y su dinamica, la radiacion solar que proporciona energia y calor y el agua que hace posible la vida, determinen el tiempo tal y como lo percibimos.

Coronary artery segmentation from CT scans is a helpful tool for coronary artery diseases diagnosis, which is frequently characterised by a vessel narrowing (stenosis). This is a highly demanded and high time-consuming process, thus automated procedures are becoming increasingly necessary. In this work, we propose an extremely light computationally 2D UNet that uses transfer learning for the first time in CT images. We compare the results, using different architectures and backbones, of a 2D UNet and a 3D UNet trained from scratch (i.e. weights are randomly initialised) and a 2D EfficientUNet. Both the amount of input data, with a total of 88 patients, and the extension of the structure to be recognised, the aorta and the coronary arteries (A + C.A), as well as the coronary arteries only (C.A) are analysed. Network outputs in clinically identified stenotic lesion areas are also assessed. The results show the advantage of using transfer learning when datais scarce, improving the F1 score by up to 0.6 points for the 2D UNet. On the other hand, when data is sufficient, F1 score values are close to 0.9 for all the networks. Besides, the results reveal that the 2D UNet distinguishes the thinnest and most distal vessels, although in the presence of a lesion, there is a clear tendency to overestimate it. The network with the best accuracy is the 3D UNet, with values above 95% and 75% in A + C.A and C.A, respectively. Moreover, the proposed methods show dependence on the amount of training data and dataset structure (A + C.A or C.A).

Cobia (Rachycentron canadum) is a coastal pelagic migratory fish species of tropical and subtropical waters, where it is an important game fish and it has been commercially expanded in offshore aquaculture systems. Understanding population connectivity is of utmost importance to the sustainable use and conservation of aquatic resources, and information on genetic diversity and structure is key element in unraveling differentiation when no clear physical barriers exist. In the present study, cobia genetic diversity and structure were depicted using mitochondrial DNA cytochrome b sequencing and microsatellite genotyping in samples from the Southwestern Atlantic and showed that a major single population inhabits the southern hemisphere. Cytochrome b sequencing also suggested that the Indian Ocean is the center of origin for this species' diversification. A hierarchical analysis of AMOVA compared sampling locations from the Northwestern Atlantic (from a previous study) with the Southwestern ones using nine shared microsatellite markers. Differentiation among groups (F-CT = 0.41), Bayesian clustering analysis, and complementary ordination analyses (by discriminant analysis of principal components [DAPC] and factorial correspondence analysis [3D-FCA]) presented a clear separation between the two hemispheres, supported by a Lagrangian model that explained the ocean dynamics over larval retention on the Western Atlantic. Another genetic subgroup intermingled with the main Southwestern group may also exist further south, probably associated with the Vitoria-Trindade Ridge and the local current systems. The distribution of this species in metapopulations is of extreme relevance for fisheries and fish hatcheries management in the Atlantic Ocean.

Marine debris is a growing problem in recent years due to population growth around the world. The incorrect management of plastic waste causes these bodies reach the seas and oceans, becoming a worldwide problem. Once they reach the seas and oceans, they begin a long period of degradation, moving from a macro state (plastics whose diameter is greater than 0.5 cm) to a micro state (diameter less than 0.5 cm). The microplastics spread throughout the oceans, entering the food chain of marine species and, subsequently, of humans. Therefore, it is important to stop the problem while it remains at the macroscale. In this work, a validation of a recently developed Lagrangian computational model to track the movement of macro plastics in seas and oceans is presented. This validation is performed on a regional scale, in the Ría de Arousa, one of the most important estuaries for mussel cultivation in northwestern Spain. During mussel cultivation in rafts, a type of floating plastic stick are released, the mussel-pegs. The potential of this study is that we can compare the accumulation results of the model with the accumulation data collected on the Galician beaches. In a general framework, the influence of wind on the spatial distribution of the accumulations given by the model was observed. For the monitoring data, similar results were found for the accumulation trends over the entire total period. For the monthly representation, some discrepancies were observed. These differences can be attributed to particular synoptic situations, poor reproduction of the coastline or to the very orientation of the study area with respect to the intertidal dynamics.

Abstract A priori, cosmic‐ray measurements offer a unique capability to determine the vertical profile of atmospheric temperatures directly from ground. However, despite the increased understanding of the impact of the atmosphere on cosmic‐ray rates, attempts to explore the technological potential of the latter for atmospheric physics remain very limited. In this paper, we examine the intrinsic limits of the process of cosmic‐ray data inversion for atmospheric temperature retrieval, by combining a detection station at ground with another one placed at an optimal depth, and making full use of the angular information. With that aim, the temperature‐induced variations in cosmic rays (c.r.) rates have been simulated resorting to the theoretical temperature coefficients WT(h, θ, Eth) and the temperature profiles obtained from the ERA5 atmospheric reanalysis. Muon absorption and Poisson statistics have been included to increase realism. The resulting c.r. sample has been used as input for the inverse problem and the obtained temperatures compared to the input temperature data. Relative to early simulation works, performed without using angular information and relying on underground temperature coefficients from a suboptimal depth, our analysis shows a strong improvement in temperature predictability for all atmospheric layers up to 50 hPa, nearing a factor 2 error reduction. Furthermore, the temperature predictability on 6‐h intervals stays well within the range 0.8–2.2 K. Most remarkably, we show that it can be achieved with small‐area m2‐scale muon hodoscopes, amenable nowadays to a large variety of technologies. For mid‐latitude locations, the optimal depth of the underground station is around 20 m.

The onset of viscous fingering in the presence of a viscosity profile is investigated theoretically for two immiscible fluids undergoing a time-dependent injection. Here, we show that the presence of a positive viscosity gradient at the interface between both fluids stabilizes the interface facilitating the spread of the perturbation. This effect is much more pronounced in the case of sinusoidal injection flows. The influence of the viscosity gradient on the dispersion relation is analyzed. Numerical simulations of the Navier-Stokes equation confirm the linear stability analysis.

The vestibular system of each individual is different and, thus the methodology to analyze any related pathology should be adjusted to his/her specificities. Based on mathematical models of the membranous labyrinth and their simulation by means of Computational Fluid Dynamics techniques, we evaluate how different planes of rotation affect the vestibular diagnosis. We demonstrate that a different plane of rotation, selected following the angular relationships between the planes of the semicircular canals, helps to distinguish each cupular stimulus contribution on the nystagmus, resulting in an optimization of the rotational testing of the vestibular function.Funding Information: This research is supported by the Spanish Ministerio de Economía y Competitividad and European Regional Development Fund, research grant RTI2018-097063-B-I00 AEI/FEDER, UE; and by Xunta de Galicia, Research Grant No 2021-PG036.Declaration of Interests: All authors declare no competing interest related to this article.Ethics Approval Statement: Ethical Approval was not required as this is theoretical study and did not involve the use of confidential personal data

The ionization caused by Cosmic Rays (CR) in the atmosphere can influence the growth of aerosols that will modify the density of cloud-condensation nuclei (CCN). In fact, the flux of CR in the atmosphere has been reported to correlate with cloud and aerosol properties. Several mechanisms have been proposed and tested to explain this effect, leading to the conclusion that the induced effects were minor. Still, these studies did not completely disprove the link between CR and clouds (i.e., climate). Since then, different mechanisms that could be relevant to aerosol growth have been proposed. One of them is the diffusion-charging mechanism by which aerosols acquire charges by diffusion of atmospheric ions onto their surface. Charging and aerosol coagulation can influence each other and impact the particle charge and size distributions in the atmosphere. Previous works have developed approaches to explicitly solve all the equations governing charge and size distribution in particles. However, since aerosols can acquire a large number of charges, the number of equations to solve would be immense and very computationally expensive. Fortunately, other approaches have also been developed that allow diffusion charging to be implemented more efficiently. In this work, we use for the very first time a global chemistry transport model (GEOS-Chem) to implement the effects of diffusion charging from CR on the microphysical development of aerosols following those approaches. We compare the variations of CCN concentrations between the solar maximum and the solar minimum (i.e., different atmospheric ionization scenarios) to test the sensitivity of the effect. Results indicate that the influence of diffusion charging can be relevant under several atmospheric conditions. In such cases, the change in the concentrations of CCN between the solar maximum (high cosmic-ray flux) and the solar minimum (low cosmic-ray flux) is found to be larger than 1%, which may become relevant for cloud formation.

Concern about heavy precipitation events has increasingly grown in the last years in southern Europe, especially in the Mediterranean region. These occasional episodes can result in more than 200 mm of rainfall in less than 24 h, producing flash floods with very high social and economic losses. To better understand these phenomena, a correct identification of the origin of moisture must be found. However, the contribution of the different sources is very difficult to estimate from observational data; thus numerical models are usually employed to this end. Here, we present a comparison between two methodologies for the quantification of the moisture sources in two flooding episodes that occurred during October and November 1982 in the western Mediterranean area. A previous study, using the online Eulerian Weather Research and Forecasting (WRF) Model with water vapor tracer (WRF-WVT) model, determined the contributions to precipitation from moisture evaporated over four different sources: (1) the western Mediterranean, (2) the central Mediterranean, (3) the North Atlantic Ocean and (4) the tropical and subtropical Atlantic and tropical Africa. In this work we use the offline Lagrangian FLEXPART-WRF model to quantify the role played by these same sources. Considering the results provided by WRF-WVT as “ground truth”, we validated the performance of the FLEXPART-WRF. Results show that this Lagrangian method has an acceptable skill in identifying local (western Mediterranean) and medium-distance (central Mediterranean and North Atlantic) sources. However, remote moisture sources, like tropical and subtropical areas, are underestimated by it. Notably, for the October event, the tropical and subtropical area reported a relative contribution 6 times lower than with the WRF-WVT. In contrast, FLEXPART-WRF overestimates the contribution of some sources, especially from North Africa. These over- and underestimates should be taken into account by other authors when drawing conclusions from this widely used Lagrangian offline analysis.