Similar Velocity Research Articles

The actuator farm model for large eddy simulation (LES) of wind-farm-induced atmospheric gravity waves and farm–farm interaction

Abstract. This study introduces the actuator farm model (AFM), a novel parameterization for simulating wind turbines within large eddy simulations (LESs) of wind farms. Unlike conventional models like the actuator disk (AD) or actuator line (AL), the AFM utilizes a single actuator point at the rotor center and only requires two to three mesh cells across the rotor diameter. Turbine force is distributed to the surrounding cells using a new projection function characterized by an axisymmetric spatial support in the rotor plane and Gaussian decay in the streamwise direction. The spatial support's size is controlled by three parameters: the half-decay radius r1/2, smoothness s, and streamwise standard deviation σ. Numerical experiments on an isolated National Renewable Energy Laboratory (NREL) 5MW wind turbine demonstrate that selecting r1/2=R (where R is the turbine radius), s between 6 and 10, and σ≈Δx/1.6 (where Δx is the grid size in the streamwise direction) yields wake deficit profiles, turbine thrust, and power predictions similar to those obtained using the actuator disk model (ADM), irrespective of horizontal grid spacing down to the order of the rotor radius. Using these parameters, LESs of a small cluster of 25 turbines in both staggered and aligned layouts are conducted at different horizontal grid resolutions using the AFM. Results are compared against ADM simulations employing a spatial resolution that places at least 10 grid points across the rotor diameter. The wind farm is placed in a neutral atmospheric boundary layer (ABL) with turbulent inflow conditions interpolated from a previous simulation without turbines. At horizontal resolutions finer than or equal to R/2, the AFM yields similar velocity, shear stress, turbine thrust, and power as the ADM. Coarser resolutions reveal the AFM's ability to accurately capture power at the non-waked wind farm rows, although it underestimates the power of waked turbines. However, the far wake of the cluster can be predicted well even when the cell size is of the order of the turbine radius. Finally, combining the AFM with a domain nesting method allows us to conduct simulations of two aligned wind farms in a fully neutral ABL and of wind-farm-induced atmospheric gravity waves under a conventionally neutral ABL, obtaining excellent agreement with ADM simulations but with much lower computational cost. The simulations highlight the AFM's ability to investigate the mutual interactions between large turbine arrays and the thermally stratified atmosphere.

Experimental study on the spray characteristics of high-pressure liquid ammonia under different ambient conditions

As a promising carbon-free fuel, ammonia is expected to be widely applied in internal combustion engines. However, the physical properties of ammonia are quite different from those of conventional fuels, which leads to different spray characteristics. In this paper, the ammonia spray under injection pressure as high as 80 MPa was visualized by the diffused back-illumination imaging method, and the liquid ammonia spray characteristics under different ambient pressures and ambient temperatures were analyzed. The liquid spray penetration length, cone angle and tip velocity calculated from the spray images provide a reference database for numerical simulation. The results show that the development characteristics of liquid ammonia spray are significantly different under flare flash boiling, transitional flash boiling and non-flash boiling conditions. Flash boiling (especially flare flash boiling) inhibits the initial liquid spray penetration. The spray tip velocity increases first and then gradually decreases under flash boiling conditions. Ammonia spray has obvious radial expansion at the initial stage of flare flash boiling and the spray contour under flare flash boiling conditions is noticeably distorted, forming an obvious dilute region. With the increase of ambient pressure, the intensity of flash boiling reduces, the dilute region gradually disappears, and the distortion of the spray contour gradually weakens. Under non-flash boiling conditions, ammonia spray presents a dense and regular shape; there is no spray acceleration but a sharp decrease in spray tip velocity at the initial stage, and then the spray penetrates forward at a similar velocity. The spray penetration velocity decreases significantly with the increase of ambient pressure. The increase in ambient temperature accelerates the vaporization of ammonia spray. The liquid spray penetration length decreases and maintains with only slight fluctuations during the injection process as the ambient temperature increases from 300 K to 600 K because the vaporization rate and penetration velocity reach a balance.

Patient-specific gait pattern in individuals with patellofemoral instability reduces knee joint loads

Patellofemoral instability is influenced by morphological factors and associated with compensational alterations in gait pattern. Recent simulation studies investigated the impact of knee morphology on the stability and loading of the patellofemoral joint but neglected the patient-specific gait pattern. The aim of this study was to investigate the impact of patient-specific gait pattern on muscle forces and joint loading in individuals with patellofemoral instability. Musculoskeletal simulations with a model including a twelve degrees of freedom knee joint were performed based on three-dimensional motion capture data of 21 individuals with chronic patellofemoral instability and 17 healthy control participants. The patellofemoral instability group walked with a less flexed knee joint and reduced knee flexion and abduction moments compared to the control group, which required less quadriceps muscle forces. Lower quadriceps muscle forces resulted in a reduction of tibiofemoral and patellofemoral joint contact forces despite similar walking velocities between both groups. Furthermore, we observed decreased lateralizing patella forces in subjects with patella instability, which could potentially reduce the risk of patella dislocation. Our findings highlight the importance of accounting for the patient-specific gait pattern when analysing knee loads in individuals with patellofemoral instability.

Near‐Infrared Dual‐Band Frequency Comb Generation from a Silicon Resonator

AbstractBenefitting from the mature, cost‐effective, and scalable manufacturing capabilities of complementary metal‐oxide‐semiconductor (CMOS) technology, silicon photonics has facilitated the seamless and monolithic integration of diverse functionalities, including optical sources, modulators, and photodetectors. Microresonators can generate multiple coherent optical frequency comb lines and serve as optical sources. However, at the telecom band, silicon suffers from two‐photon absorption and free‐carrier absorption, which severely hampers the realization of microcombs from a single silicon chip at telecom wavelengths until now. In this paper, a novel approach is presented and demonstrated with near‐infrared dual‐band frequency combs from a multimode silicon resonator. With a single pumping configuration, dual‐band combs are generated from the interaction between the pump and Raman Stokes fields by involving two different optical mode families but with similar group velocities. It is observed that the pump power required to generate dual‐band combs is as low as 0.7 mW. The work in bringing telecom microcombs to the silicon platform will advance silicon photonics for the next generation of monolithically integrated technology based on a single silicon chip, enabling new possibilities for further exploring silicon photonics‐based applications in optical telecommunications, sensing, and quantum metrology in the telecom band using a monolithic single silicon chip.

Imaging Complex Structures of the Los Angeles Basin via Adjoint-State Travel-Time Tomography

ABSTRACT In this study, we present high-resolution seismic velocity models for the Los Angeles basin (LAB) and its adjacent area using adjoint-state travel-time tomography, fitting an extensive database of P- and S-wave travel times accumulated from 1980 to 2021. We select 151,193 first P-wave travel times and 149,997 first S-wave travel times from local earthquakes archived in the Southern California Earthquake Data Center to determine the velocity models, with earthquake locations updated at each iteration. With seismic stations spaced more than 3.5 km apart, our dataset has limited resolution in the uppermost 1–2 km. However, starting from three different initial models, our VP models, which are optimally imaged between 3 and 15 km, show similar velocity heterogeneity and provide a better fit to the observed first travel-time data compared to the Community Velocity Model-Harvard 15.1.0 and Community Velocity Model-Southern California Earthquake Center 4.26. Our models provide a detailed delineation of the subsurface structure beneath the LAB, revealing significant velocity variations across active faults, a 10-km-thick sequence of sedimentary rocks within the basin, and a distinct basin margin marked by transitions from low to high-velocities. In addition, these models highlight basement structures with elevated VP and VS located at depths of 9 to 12 km and beyond. Specifically, beneath the northeastern part of the basin, the models demonstrate improved accuracy and reliability in reflecting the linear relationship between VP and VS in mafic rocks. The accurate delineation of the basin’s structure provided by our models could also offer robust constraints for seismic response modeling and seismic hazard assessment in the region.

Chloroplast redox state mediates the short-term regulation of leaf isoprene emission.

Isoprene emission from plants not only confers thermoprotection, but also has profound impacts on atmospheric chemistry and the climate. Leaf isoprene emission is dynamically regulated in response to various environmental cues, but the exact mechanism remains unclear. It has been proposed that chloroplast redox/energy state or cytosolic phosphoenolpyruvate carboxylation regulates isoprene biosynthesis and consequently emission, and the latter has been disproven by recent literature. However, the possible covariation of chloroplast redox/energy state and cytosolic PEP carboxylation in previous experiments impedes the independent examination of the former hypothesis. We developed an index of chloroplast redox state and showed its validity by examining the relationships between the index and the rates of certain processes which have been demonstrated to be affected or unaffected by chloroplast redox/energy state. According to the former hypothesis alone, we modelled how isoprene emission rate (IER) responded to different short-term environmental variations, and compared theoretical predictions with experimental data. We predicted that no matter which environmental factor was varied, IER would respond to the index of chloroplast redox state with similar velocities. We found that IER showed comparable increasing rates in response to the increase in the index of chloroplast redox state caused by different environmental variations (0.0479, 0.0439 or 0.0319 when ambient CO2 concentration, photosynthetic photon flux density or leaf temperature was varied, respectively). These results support that chloroplast redox/energy state regulates isoprene biosynthesis, leading to dynamic isoprene emission in nature.

Identifying Subsurface Connectivity From Observations: Experimentation With Equifinality Defines Both Challenges and Pathways to Progress

ABSTRACTLinkages between landscapes and streams are increasingly described in terms of hydrological connectivity. The ability to effectively distinguish different patterns of water movement through catchments makes connectivity particularly interesting to both scientists and practical water managers. Hydrometric data (groundwater levels, soil moisture and streamflow) are often employed to infer the connection between the landscape and its drainage network. Such observational data, however, are insufficient to infer subsurface connectivity in humid settings with perennial stream flow, due to the risk of equifinality. To quantify how much subsurface flow patterns can differ and still be consistent (equifinal) with comprehensive observations of hillslope groundwater levels and stream runoff (the hydrometric data), this study used a modelling experiment based on a well‐characterised field site. Particle‐tracking simulations at different flow rates defined the water flow paths and transit times of two virtual hillslopes that differed profoundly in the vertical distribution of the saturated hydraulic conductivity. Even though the simulated weekly stream flows and groundwater levels were similar (i.e., the hillslopes were hydrometrically equifinal) particle velocities and water ages at specific locations along these hillslopes differed by orders of magnitude. Flow path lengths and catchment transit times varied up to several 100%. The hillslope‐ and stream‐based metrics used to describe connectivity also varied with stream flow rates. These results underline the need to recognise the risks for equifinality when inferring subsurface connectivity from hydrometric observations alone, even when those observations are comprehensive. The results also highlight the value of model simulations for quantifying the uncertainty in the inferred connectivity, targeting the best sampling locations/times to reduce this uncertainty with tracer data and better understanding the way connectivity influences stream chemistry.

How Do Primordial Black Holes Change the Halo Mass Function and Structure?

We examine the effects of massive primordial black holes (PBHs) on cosmic structure formation, employing both a semianalytical approach and cosmological simulations. Our simulations incorporate PBHs with a monochromatic mass distribution centered around 106 M ⊙, constituting a fraction of 10−2 to 10−4 of the dark matter (DM) in the Universe, with the remainder being collisionless particle DM. Additionally, we conduct a ΛCDM simulation for comparative analysis with runs that include PBHs. At smaller scales, halos containing PBHs exhibit similar density and velocity dispersion profiles to those without PBHs. Conversely, at larger scales, PBHs can expedite the formation of massive halos and reside at their centers owing to the “seed effect.” To analyze the relative distribution of PBH host halos compared to non-PBH halos, we apply nearest neighbor statistics. Our results suggest that PBH host halos, through gravitational influence, significantly impact the structure formation process, compared to the ΛCDM case, by attracting and engulfing nearby newly formed minihalos. Should PBHs constitute a fraction of DM significantly larger than ∼10−3, almost all newly formed halos will be absorbed by PBH-seeded halos. Consequently, our simulations predict a bimodal feature in the halo mass function, with most of the massive halos containing at least one PBH at their core and the rest being less massive non-PBH halos.

Proposal for Low-Cost Optical Sensor for Measuring Flow Velocities in Aquatic Environments.

The ocean, with its intricate processes, plays a pivotal role in shaping marine life, habitats, and the Earth's climate. This study addresses issues such as beach erosion, the survival of propagules from species like Posidonia oceanica, and nutrient distribution. To tackle these challenges, we propose an innovative sensor that quantifies hydrodynamic velocity by measuring the output voltage derived from detecting changes in light absorption and scattering using LEDs and LDRs. Our results not only demonstrate the effectiveness of the sensor but also the accuracy of the processing algorithm. Notably, the blue LED exhibited the lowest mean relative error of 7.59% in freshwater, while the yellow LED was most precise in chlorophyll-containing water, with a mean relative error of 6.80%. In a runoff simulation, we observed similar velocities with the blue, green, and white LEDs, 6.89 cm/s, 6.99 cm/s, and 7.05 cm/s, respectively, for nearly identical time intervals. It is important to highlight that our proposed sensor is not only effective but also highly cost-efficient, representing less than 0.43% of the cost of a Nortek Vector 6 MHz and 0.18% of the Teledyne Workhorse II 300 kHz Marine. This makes it a key tool for managing marine ecosystems sustainably.

Protective potential of high-contrast mineral-bonded layers on reinforced concrete slabs subjected to uniform shock waves

This study compares the blast performance of reinforced concrete (RC) slabs with and without strengthening on the impact-facing side. The strengthening strategy employed the application of two thin layers of materials with a high mutual stiffness offset, i.e., high-contrast layers. The first is a low-strength, low-modulus damping layer made of infra-lightweight concrete, followed by a second layer of high-ductility fiber-reinforced concrete. The plain RC slabs under investigation vary in thickness of either 40mm or 100mm. The layered specimens consist of a 40mm thick RC slab strengthened with a 40mm damping layer and a 20mm cover SHLC3 layer. This configuration enables a comparison of its behavior with the unstrengthened specimen (a plain 40mm thick RC slab) and a specimen with a similar eigenfrequency (the plain 100mm thick RC slab). The employed shock tube subjects the specimens to two rapidly rising areal pressures: a low-pressure wave reaching approximately 0.4MPa and a high-pressure wave peaking at around 1.2MPa. The study assesses the specimens’ response in terms of accelerations, velocities, and deformations. Additionally, it evaluates damage by analyzing crack patterns, Ultrasonic Pulse Velocity (UPV) measurements, and damping analysis. Overall, the layered specimens exhibited performance nearly equivalent to the 100mm thick specimens, displaying similar deformations and velocities despite having lower mass and bending stiffness. The high-pressure shock wave hardly damaged the layered specimens, unlike the 40mm thick slabs.

Influence of inlet velocity on the separation performance of a combined hydrocyclone

Hydrocyclone separation exploits centrifugal force to differentiate particles based on their sizes and densities, yet challenges arise when small, dense particles and large, low-density ones settle at similar velocities. To address this, we propose a two-stage combined hydrocyclone for accurate separation. Using numerical simulations, we examine the internal flow field and performance of this system. Our findings reveal that the primary hydrocyclone achieves size-dependent classification, while the secondary one achieves density-dependent sorting. Increasing inlet velocity enhances separation efficiency and accuracy by improving flow field dynamics, albeit at the cost of increased energy consumption and material residence time. Thus, optimizing inlet velocity is vital for maximizing the separation performance and operational efficacy of the combined hydrocyclones.

Breaststroke and butterfly intercycle kinematic variation according to different competitive levels with Statistical Parametric Mapping analysis

Breaststroke and butterfly are complex swimming techniques requiring refined motor skills to perform successfully, with coordinated and consistent interaction between propulsive and resistive forces being decisive when considering swimmers expertise. The current study analysed those techniques intercycle kinematic variation in two swimmers cohorts. Twenty elite and 15 national level swimmers performed one 25 m breaststroke and one 25 m butterfly sprints, with an underwater camera recording images at 120 Hz in the sagittal plane. Mean velocity, maximum and minimum velocities, stroke rate and length, intracycle velocity variation and phases relative duration were calculated for consecutive cycles (elite: five breaststroke/butterfly, national level: eight breaststroke/seven butterfly). The two highest peaks and the lower peak in between in breaststroke were also addressed. Intercycle and inter-groups analysis were performed using ANOVA, ANCOVA and Statistical Parametric Mapping. Elite and national level differed regarding breaststroke mean and maximum velocities, 1st and 2nd peaks and minimum between peaks (1.30 ± 0.02 vs 1.15 ± 0.02 m/s, 2.13 ± 0.05 vs 1.88 ± 0.06 m/s, 1.63 ± 0.05 vs 1.48 ± 0.05 m/s, 2.13 ± 0.05 vs 1.86 ± 0.05 m/s, 1.33 ± 0.04 vs 1.23 ± 0.04 m/s), and butterfly mean, maximum and minimum velocities, stroke rate and intracycle velocity variation, respectively (1.65 ± 0.01 vs 1.50 ± 0.01 m/s, 2.20 ± 0.04 vs 2.09 ± 0.04 m/s, 1.12 ± 0.04 vs 0.79 ± 0.04 m/s, (57.9 ± 0.9 vs 54.9 ± 1.0cycles/min, 18.4 ± 1.3 vs 23.7 ± 1.3 %). Elite and national level swimmers showed consistent breaststroke intercycle kinematic variation, but a butterfly mean velocity decay, with the upper limbs release and recovery, and the outsweep phases originating variability between butterfly cycles. Skill levels contrasted in technical and strategic features at sprint breaststroke and butterfly but showed similar velocity variability between consecutive swimming cycles.

Physical conditions in Centaurus A’s northern filaments

We present the first observations of HCO+(1–0) and HCN(1–0) emission in the northern filaments of Centaurus A with ALMA. HCO+(1–0) is detected in nine clumps of the Horseshoe complex, with similar velocities as the CO(1–0) emission. Conversely, HCN(1–0) is not detected, and we derive upper limits on the flux. At a resolution of ∼40 pc, the line ratio of the velocity-integrated intensities IHCO+/ICO varies between 0.03 and 0.08, while IHCO+/IHCN is higher than unity, with an average lower limit of 1.51. These ratios are significantly higher than what is observed in nearby star-forming galaxies. Moreover, the ratio IHCO+/ICO decreases with increasing CO-integrated intensity, contrary to what is observed in the star-forming galaxies. This indicates that the HCO+ emission is enhanced and may not arise from dense gas within the Horseshoe complex. This hypothesis is strengthened by the average line ratio IHCN/ICO < 0.03, which suggests that the gas density is rather low. Using non-local thermal equilibrium, large velocity gradient modelling with RADEX, we explored two possible phases of the gas, which we call ‘diffuse’ and ‘dense’ and are characterised by a significant difference in the HCO+ abundance relative to CO, respectively NHCO+/NCO = 10−3 and NHCO+/NCO = 3 × 10−5. The average CO(1–0) and HCO+(1–0) integrated intensities and the upper limit on HCN(1–0) are compatible with both diffuse (nH = 103 cm−3, Tkin = 15 − 165 K) and dense gas (nH = 104 cm−3, Tkin > 65 K). The spectral setup of the present observations also covers SiO(2–1). While undetected, the upper limit on SiO(2–1) is not compatible with the RADEX predictions for the dense gas. We conclude that the nine molecular clouds detected in HCO+(1–0) are likely dominated by diffuse molecular gas. While the exact origin of the HCO+(1–0) emission remains to be investigated, it is likely related to the energy injection within the molecular gas that prevents gravitational collapse and star formation.

Massive star cluster formation

Two main mechanisms have classically been proposed for the formation of runaway stars. In the binary supernova scenario (BSS), a massive star in a binary explodes as a supernova, ejecting its companion. In the dynamical ejection scenario, a star is ejected during a strong dynamical encounter between multiple stars. We propose a third mechanism for the formation of runaway stars: the subcluster ejection scenario (SCES), where a subset of stars from an infalling subcluster is ejected out of the cluster via a tidal interaction with the contracting gravitational potential of the assembling cluster. We demonstrate the SCES in a star-by-star simulation of the formation of a young massive cluster from a 106 M⊙ gas cloud using the TORCH framework. This star cluster forms hierarchically through a sequence of subcluster mergers determined by the initial turbulent, spherical conditions of the gas. We find that these mergers drive the formation of runaway stars in our model. Late-forming subclusters fall into the central potential, where they are tidally disrupted, forming tidal tails of runaway stars that are distributed highly anisotropically. Runaways formed in the same SCES have similar ages, velocities, and ejection directions. Surveying observations, we identify several SCES candidate groups with anisotropic ejection directions. The SCES is capable of producing runaway binaries: two wide dynamical binaries in infalling subclusters were tightened through ejection. This allows for another velocity kick via subsequent via a subsequent BSS ejection. An SCES-BSS ejection is a possible avenue for the creation of hypervelocity stars unbound to the Galaxy. The SCES occurs when subcluster formation is resolved. We expect nonspherical initial gas distributions to increase the number of calculated runaway stars, bringing it closer to observed values. The observation of groups of runaway stars formed via the SCES can thus reveal the assembly history of their natal clusters.

Multiwavelength study of on-disk coronal-hole jets with IRIS and SDO observations

Context. Solar jets are an important field of study, as they may contribute to the mass and energy transfer from the lower to the upper atmosphere. Aims. We use the Interface Region Imaging Spectrograph (IRIS) and Solar Dynamic Observatory (SDO) observations to study two small-scale jets (jet 1 and jet 2) originating in the same on-disk coronal hole observed in October 2013. Methods. We combine dopplergrams, intensity maps, and line width maps derived from IRIS Si IV 1393.755 Å spectra along with images from the Atmospheric Imaging Assembly (AIA) on SDO to describe the dynamics of the jets. Images from AIA, with the use of the emission measure loci technique and rectangular differential emission measure (DEM) distributions, provide estimations of the plasma temperatures. We used the O IV 1399.77 Å, 1401.16 Å spectral lines from IRIS to derive electron densities. Results. For jet 1, the SDO images show a small mini-filament 2 minutes before the jet eruption, while jet 2 originates at a pre-existing coronal bright point. The analysis of asymmetric spectral profiles of the Si IV 1393.755 Å and 1402.770 Å lines reveals the existence of two spectral components at both regions. One of the components can be related to the background plasma emission originating outside the jet, while the secondary component represents higher-energy plasma flows associated with the jets. Both jets exhibit high densities of the order of 1011 cm−3 at their base and 1010 cm−3 at the spire, respectively, as well as similar average nonthermal velocities of ∼50–60 km/s. However, the two jets show differences in their length, duration, and plane-of-sky velocity. Finally, the DEM analysis reveals that both jets exhibit multithermal distributions. Conclusions. This work presents a comprehensive description of the thermal parameters and the dynamic evolution of two jets. The locations of the asymmetric profiles possibly indicate the areas of energy release triggering the jets.

Natural ventilation in large spaces: CFD simplified model validated with full-scale experimental data of Roman Baths

This study addresses the escalating need for energy-efficient and well-ventilated buildings by examining natural ventilation in large spaces. Validation of a CFD model was pursued through in-site experiments at the Roman Baths Museum in Chaves, Portugal. A sensitivity analysis aimed to determine the optimal number of monitoring points for model validation, crucial for establishing procedures in large-volume settings. Findings emphasized the feasibility of using a minimal number of monitored points, notably with a 3 × 3 test point arrangement, showcasing consistent temperature variations with low relative errors (0.50 %–1.75 %). Furthermore, the validated model assessed ventilation performance under diverse operational conditions, revealing slight enhancements in experimental settings, including an increase in air change rate (2.4 vs. 2.2 ACH) and a decrease in buoyancy dominance (Richardson number 197.3 vs. 241.3) compared to design conditions. Quantitative analysis highlighted similar temperature and velocity trends, with greater stratification in experimental conditions (temperature ratios 0.12 to 0.36 vs. 0.10 to 0.32). Qualitative assessments align with the quantitative analysis and enable the identification of stagnation zones and airflow distribution patterns. These findings affirm the methods' reliability in analysing ventilation in large spaces naturally ventilated, validating the model across diverse contexts, despite fewer data points.

Professional baseball pitchers produce similar ball velocity and kinematics when pitching from the wind-up and stretch deliveries: a biomechanical analysis

ABSTRACT Historically, the wind-up delivery is considered a more biomechanically advantageous pitching motion compared to the stretch. Recently, some pitchers have shifted to pitching exclusively from the stretch regardless of the game situation. The goal of this study was to compare temporal, kinematic and kinetic variables between the wind-up and stretch deliveries. Professional pitchers (n = 52, 189.1 ± 4.8 cm, 92.8 ± 8.4 kg) threw fastballs evaluated by 3D-motion capture (480 Hz) from both the wind-up and stretch deliveries. Within a pitcher, there was no significant difference in ball velocity between the two deliveries (p = 0.15). The stretch delivery was significantly quicker to ball release at toe off 2 (p < 0.001) (the last frame the pitcher’s foot contacts the ground before progressing to maximum knee height) and maximum knee height (p < 0.001). The majority of differences occurred prior to foot contact. The wind-up delivery produced greater maximum shoulder external rotation (p < 0.001) and lead knee flexion at ball release (p < 0.001). Pitching from the stretch incurred greater shoulder superior force (p < 0.001). It remains unknown if this is clinically significant as pooled means show only a 2% difference. Therefore, pitching a fastball from either the wind-up or stretch delivery provides comparable mechanics and throwing arm load with likely comparable risk of injury.

Dual ProGlide vs ProGlide and Angio-Seal for Femoral Access Hemostasis After Transcatheter Aortic Valve Replacement: A Randomised Comparative Trial

BackgroundVascular complications increase morbidity and mortality after transcatheter aortic valve replacements (TAVR), often related to failures in vascular closure devices (VCDs). We intended to compare the dual Perclose ProGlide (PP) strategy and the hybrid combination of PP and Angio-Seal (AS) for femoral access hemostasis after TAVR. MethodsA randomised controlled trial with 257 patients comparing dual PP with 1 PP and 1 AS (AS+PP) for vascular closure after transfemoral TAVR was conducted. The primary end point was the composite of TAVR access site–related vascular complications and life-threatening type 2/3 or 1 bleeding according to the Valve Academic Research Consortium 3. Secondary end points included additional VCD use and significant peripheral ischemia related to arteriotomy closure within 1 year. Modified VCD failure, defined as failure to achieve hemostasis within 5 minutes or requiring additional endovascular manoeuvres, was also recorded. ResultsThe AS+PP combination yielded lower rates of the primary end point (18.2% vs 29.8%; P = 0.0381), vascular complication (18.2% vs 29.8%; P = 0.0381), additional VCD use (0.8% vs 19.0%; P < 0.0001), and modified VCD failure (9.9% vs 33.1%; P < 0.0001) than the dual PP. Bleeding complication rates were similar between the 2 groups. Three-month follow-up vascular duplex tests showed similar common femoral artery (CFA) diameters and peak systolic velocities (PSVs) between the 2 groups, but those with additional intervention had higher PSVs and smaller CFA diameters than those without. ConclusionsCombined PP+AS for large-bore femoral access hemostasis after TAVR promises to be more effective and safer than dual PP in terms of vascular complications. Moreover, additional intervention for vascular complications resulted in smaller CFA diameters. Clinical Trial RegistrationNCT05491070

Enhancing water transportation capacity by asymmetrical patterned surface with super-wettability

Spontaneous and directional water droplet transportation based on patterned surface with super-wettability is crucial for the development of frontier science technology. However, water droplet transportation cannot meet both long distance and fast transportation simultaneously. Here, we overcame this limitation by proposing an asymmetric serial brachistochrone-shaped pattern (ASBP). Water droplet could be transported on the ASBP with a transportation distance of 72.52 mm and a transportation velocity of 158 mm/s after a series of single-factor experiments, orthogonal design optimization, and junction transition optimization. In addition, the water droplet could be transported on a curved ASBP, a super-long ASBP for multi-droplet scenarios, and an ASBP at an inclination angle. Moreover, acidic and alkaline aqueous solution droplet showed similar transportation distance and transportation velocity on the ASBP. Based on the aforementioned superb water transportation capacity, this ASBP can be applied in the fields of fog collection, solution mixing and reaction, and reagent detection. This work has strong implications for promoting the application of patterned surface with super-wettability in the field of high-performance fluid transportation systems.

Fastball Quality After Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers

Background: The ulnar collateral ligament (UCL) is essential for elbow stability during pitching. In professional baseball, the fastball (FB) is the most commonly used pitch, making postrecovery FB performance after UCL reconstruction (UCLR) a crucial aspect to consider. Hypotheses: (1) Pitchers undergoing UCLR would show no significant changes in performance metrics compared with nonoperated pitchers with similar FB velocity and spin rate, and (2) no significant variance would be found in these metrics within the operated pitchers concerning their preinjury anthropometric characteristics and pitching performance metrics. Study Design: Cohort study; Level of evidence, 3. Methods: The study included 91 Major League Baseball (MLB) pitchers who underwent primary UCLR between January 1, 2015, and December 31, 2021. A matched 1:1 control group of MLB pitchers without UCLR injuries was established. Publicly available pitch metrics and anthropometric data were compared between the study and control groups. Results: Disparities in several performance metrics emerged during the first postreturn year (PRY1), including FB use percentage (P = .029), fielder independent pitching (FIP) (P = .021), and standardized FB runs above average per 100 pitches (wFB/C) (P < .001). Subgroup analysis within the UCLR group revealed a negative correlation between presurgery mean FB velocity and its subsequent change (P < .001) and a positive correlation with changes in FIP (P = .025) from the index year to PRY1. A negative correlation was observed between FB use percentage in the index year and its change by PRY1 (P = .002). By the second postreturn year, no significant differences were found in these performance metrics. No factors were significantly related to prolonged recovery time. Conclusion: Although FB velocity and spin rate remained consistent, significant differences were observed in FB use percentage, FIP, and wFB/C in PRY1. However, by second postreturn year, these differences were no longer significant. No specific risk factors were identified concerning prolonged recovery time between pre-UCLR FB pitching metrics and the physical anthropometric data. These results suggest that although the short-term postsurgery period may affect more specialized pitching metrics, the basic pitching performance metrics, as hypothesized, remain largely unaffected by UCLR.