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Considering the rapid motor-cognitive changes and increased risk of injury in preadolescent athletes, this study investigated the effects of neurocognitive training (NT) on pain, proprioception, injury-related anxiety, and functional and neurocognitive performance in athletes with chronic ankle instability (CAI). Randomized controlled trial. Sports training facilities in Balıkesir, Türkiye. Thirty preadolescent athletes with CAI (mean age 11.10 ± 1.06 years) were randomly assigned to an NT group (n = 15) or a control group (n = 13). The Identification of Functional Ankle Instability (IdFAI), Cumberland Ankle Instability Tool (CAIT), pain severity, proprioception (dorsiflexion/plantarflexion), injury-related anxiety, Y Balance Test (YBT), Side Hop Test, Reactive Balance Test (RBT), and Upper Extremity Choice Reaction Time Test were evaluated pre- and post-intervention. The NT group demonstrated significant improvements in IdFAI (p < 0.001), CAIT (p = 0.004), dorsiflexion (p = 0.003) and plantarflexion proprioception (p = 0.018), injury-related anxiety (p = 0.013), YBT anterior reach (p = 0.048), RBT reaction time (p = 0.030), and accuracy (p = 0.003). The control group showed improvement only in plantarflexion proprioception (p = 0.028), with an increase in post-training pain (p = 0.030). NT reduced ankle instability symptoms and injury-related anxiety while improving proprioception and neurocognitive performance. NT may enhance functional adaptation by addressing sport-specific cognitive-motor demands. •NT reduced instability severity and injury-related anxiety in CAI athletes.•Proprioception and neurocognitive performance significantly improved after NT.•NT enhanced reactive balance and reduced lateral hop test time.•Control group showed limited gains in proprioception and post-training pain.•NT may support multidimensional rehab by targeting both motor and cognitive skills.

The influence of temperature on precipitation in China is investigated from two aspects of the atmospheric water cycle: available water vapor and atmospheric instability. Daily observations are used to analyze how rainfall intensities and its spatial distribution in mainland China depend on these two aspects. The results show that rainfall intensities, and especially rainfall extremes, increase exponentially with available water vapor. The efficiency of water vapor conversion to rainfall is higher in northwestern China where water vapor is scarce than in southeastern China where water vapor is plentiful. The results also reveal a power law relationship between rainfall intensity and convective instability. The fraction of convective available potential energy (CAPE) converted to upward velocity is much larger over southeastern China than over the arid northwest. The sensitivities of precipitation to temperature-induced changes in available water vapor and atmospheric convection are thus geographically reciprocal. Specifically, while conversion of water vapor to rainfall is relatively less efficient in southeastern China, conversion of CAPE to upward kinetic energy is more efficient. By contrast, in northwestern China, water vapor is efficiently converted to rainfall but only a small fraction of CAPE is converted to upward motion. The detailed features of these relationships vary by location and season; however, the influences of atmospheric temperature on rainfall intensities and rainfall extremes are predominantly expressed through changes in available water vapor, with changes in convective instability playing a secondary role.

Background To investigate the clinical significance of high intensity signals in interspinous ligaments at the affected segment in degenerative lumbar spondylolisthesis (DLS), as well as to determine the most effective diagnostic modalities for evaluating segmental instability. Methods This study reviewed a consecutive series of patients with L4/5 DLS between July 2023 and December 2023. The enrolled patients were divided into two groups based on the presence or absence of high-intensity signals in interspinous ligaments: the higher group (Group H), and the non-higher group (Group NH). Translational and angular motion was determined using flexion and extension (FE) radiographs or a sitting lumbar lateral radiograph with a supine sagittal MR image (combined, S-MR). The five-repetition sit-to-stand test (5R-STS) was employed to evaluate patients’ objective functional impairment (OFI). Results Overall, 73 patients were enrolled in this study, and there were 22 (30.1%) patients in group H and 51(69.9%) patients in group NH, with an average age of 60.3 ± 8.1 years. The patients in Group H exhibited significantly longer 5R-STS times and serious OFI compared to those in Group NH. Compared to Group NH, Group H exhibited significantly higher SP in the sitting position (21.8% vs 16.7%; P  < 0.001*), while no significant differences were observed in the upright, flexion, extension, and supine MRI positions (all P values > 0.05). In Group H, “instability” was recognized in 77.3% of patients using S-MR versus 40.9% patients using FE ( P  < 0.001); While in Group NH, no significant difference was observed in the incidence of “instability” between FE and s-MR (37.3% vs. 31.4%, P  = 0.53). Overall, a significantly higher incidence of instability was found in Group H compared to Group NH (77.3% vs .37.3%, P  < 0 .001*). Conclusions DLS with a high intensity within the interspinous ligaments is a distinct subgroup associated with segmental instability, the combination of 5R-STS and S-MR should be regarded as the most clinically relevant approach for assessing OFI and lumbar instability.

Although strength training is commonly used to rehabilitate ankle injuries, studies investigating the effects of strength training on proprioception have shown conflicting results. To determine the effects of a 6-week strength-training protocol on force sense and strength development in participants with functional ankle instability. Randomized controlled clinical trial. University athletic training research laboratory. A total of 40 participants with functional ankle instability were recruited. They were randomly placed into a training group (10 men, 10 women: age = 20.9 ± 2.2 years, height = 76.4 ± 16.1 cm, mass = 173.0 ± 7.9 kg) or control group (10 men, 10 women: age = 20.2 ± 2.1 years, height = 78.8 ± 24.5 cm, mass = 173.7 ± 8.2 kg). Participants in the training group performed strength exercises with the injured ankle 3 times per week for 6 weeks. The protocol consisted of a combination of rubber exercise bands and the Multiaxial Ankle Exerciser, both clinically accepted strengthening methods for ankle rehabilitation. The progression of this protocol provided increasingly resistive exercise as participants changed either the number of sets or resistance of the Thera-Band or Multiaxial Ankle Exerciser. Main Outcome Measure(s): A load cell was used to measure strength and force sense. Inversion and eversion strength was recorded to the nearest 0.01 N. Force-sense reproduction was measured at 2 loads: 20% and 30% of maximal voluntary isometric contraction. Increases in inversion (F(1,38) = 11.59, P < 0.01, η(p)(2) = 0.23, power = 0.91) and eversion (F(1,38) = 57.68, P < .01, η(p)(2) = 0.60, power = 0.99) strength were found in the training group at the posttest when compared with the control group. No significant improvements were noted in force-sense reproduction for either group. Strength training at the ankle increased strength but did not improve force sense.

Wind turbine wakes, being convectively unstable, may behave as an amplifier of upstream perturbations and make downstream turbines experience strong inflow fluctuations. In this work, we investigate the effects of the side-to-side motion of a floating offshore wind turbine (FOWT) on wake dynamics using large-eddy simulation and linear stability analysis (LSA). When the inflow turbulence intensity is low, simulation results reveal that the turbine motion with certain Strouhal numbers $St = fD/U_\\infty \\in (0.2,0.6)$ (where $f$ is the motion frequency, $D$ is the rotor diameter, and $U_\\infty$ is the incoming wind speed), which overlap with the Strouhal numbers of wake meandering induced by the shear layer instability, can lead to wake meandering with amplitudes being one order of magnitude larger than the FOWT motion for the most unstable frequency. For high inflow turbulence intensity, on the other hand, the onset of wake meandering is dominated by the inflow turbulence. The probability density function of the spanwise instantaneous wake centres is observed being non-Gaussian and closely related to that of the side-to-side motion. This complements the existing wake meandering mechanisms, that the side-to-side motion of an FOWT can be a novel origin for the onset of wake meandering. It is also found that LSA can predict the least stable frequencies and the amplification factor with acceptable accuracy for motion amplitude $0.01D$. Effects of nonlinearity are observed when motion amplitude increases to $0.04D$, for which the most unstable turbine oscillations shift slightly to lower frequencies and the amplification factor decreases.

Experiments were conducted to study the transition and flow development in a laminar separation bubble (LSB) formed on an aerofoil. The effects of a wide range of free-stream turbulence intensity ($0.15\\,\\%< Tu<6.26\\,\\%$) and streamwise integral length scale ($4.6\\ {\\rm mm}<\\varLambda _{u}<17.2\\ {\\rm mm}$) are considered. The co-existence of modal instability due to the LSB and non-modal instability caused by streaks generated by free-stream turbulence is observed. The flow field is measured using hot-wire anemometry, which showed that the presence of streaks in the boundary layer modifies the mean-flow topology of the bubble. These changes in the mean flow field result in the modification of the convective disturbance growth, where an increase in turbulence intensity is found to dampen the growth of the modal instability. For a relatively fixed level of $Tu$, the variation of $\\varLambda _{u}$ has modest effects. However, a slight advancement of the nonlinear growth of disturbances and eventual breakdown with the decrease in $\\varLambda _{u}$ is observed. The data show that the streamwise growth of the disturbance energy is exponential for the lowest levels of free-stream turbulence and gradually becomes algebraic as the level of free-stream turbulence increases. Once a critical turbulence intensity is reached, there is enough energy in the boundary layer to suppress the laminar separation bubble, resulting in the non-modal instability taking over the transition process. Linear stability analysis is conducted in the fore position of the LSB. It accurately models incipient disturbance growth, unstable frequencies and eigenfunctions for configurations subjected to turbulence intensity levels up to 3 %, showing that the mean-flow modification due to the non-modal instability dampens the modal instability.

Understanding the development and breakup of interfacial waves in a two-phase mixing layer between the gas and liquid streams is paramount to atomization. Due to the velocity difference between the two streams, the shear on the interface triggers a longitudinal instability, which develops to interfacial waves that propagate downstream. As the interfacial waves grow spatially, transverse modulations arise, turning the interfacial waves from quasi-two-dimensional to fully three-dimensional. The inlet gas turbulence intensity has a strong impact on the interfacial instability. Therefore, parametric direct numerical simulations are performed in the present study to systematically investigate the effect of the inlet gas turbulence on the formation, development and breakup of the interfacial waves. The open-source multiphase flow solver, PARIS, is used for the simulations and the mass–momentum consistent volume-of-fluid method is used to capture the sharp gas–liquid interfaces. Two computational domain widths are considered and the wide domain will allow a detailed study of the transverse development of the interfacial waves. The dominant frequency and spatial growth rate of the longitudinal instability are found to increase with the inlet gas turbulence intensity. The dominant transverse wavenumber, determined by the Rayleigh–Taylor instability, scales with the longitudinal frequency, so it also increases with the inlet gas turbulence intensity. The holes formed in the liquid sheet are important to the disintegration of the interfacial waves. The hole formation is influenced by the inlet gas turbulence. As a result, the sheet breakup dynamics and the statistics of the droplets formed also change accordingly.

Western China is a typical high-intensity seismic zone, where seismic and geological disasters are frequent. The tunnel portal slope is prone to earthquake damage, which has become the key and difficult point in engineering construction. To deeply explore the dynamic response characteristics and instability mechanism of high-steep slopes at tunnel portal under frequent earthquakes, a large-scale shaking table test was designed. This experiment mainly simulates the geological environment of a high-intensity earthquake area by applying microseismic waves several times. The test results show that the amplification coefficient of peak ground acceleration (PGA) at different stages decreases with increasing earthquake intensity and finally presents a 50% attenuation. The vertical wave has a greater effect on the dynamic response of the slope, mainly affecting the magnifying effect during the relative elevation of 0.3–0.7. The horizontal wave has a stronger amplification effect on the slope crest region. The nonconsistency of the acceleration amplification factor (MPGA) and the dynamic change characteristics of the ∆MPGA can well identify the three stages of slope failure: the elastic stage (0–2 m/s2), elastoplastic stage (2–5 m/s2), and plastic failure stage (≥ 5 m/s2). The seismic failure modes of the slope can be summarized as follows: tensile fracture is formed first at the crest and waist of the slope, shear failure occurs between the slope waist and tunnel, forming a sliding body gradually, and the slope toe uplifts and finally forms collapse failure. This work can provide a reference for the design of seismic technology for tunnel portal slopes in high-intensity areas.HighlightsTo deeply explore the dynamic response characteristics and instability mechanism of the high steep slope at the tunnel portal under frequent earthquakes, a large scale shaking table test was designed, focusing on modelling the geological environment of high intensity seismic region. The roc k mass degradation effect of complex geological slopes in high seismic regions is simulated by applying microseismic wave forms near the study area for many times.By analyzing the peak ground acceleration and its amplification coefficient, the dynamic response characteristics and instability characteristics of the slope are systematically studied. Waves in different directions have different control effects on slope failure, and complex wave field superposition exists between the slope and tunnel syste m. Meanwhile, the acceleration amplification effect at different locations can assist in identifying slope damage areas.The dynamic failure modes of steep bedding slope with tunnel structures are as follows: tensile fracture shear failure sliding failure of upper slope, collapse failure of slope toe area. The formation and penetration of fissure mainly focus on the weak interlayers of slope surface. In addition, the interlayers are prone to shear failure area, which leads to shear slip of the slope under the seismic force, while the slope toe is prone to collapse failure due to the extrusion action.

A limited area convection permitting model (CPM) based on the Met Office Unified Model, with a 0.04° (4.4 km) horizontal grid spacing, is used to simulate an entire warm-season of the East Asian monsoon (from April to September 2009). The simulations are compared to rain gauge observations, reanalysis and to a lower resolution regional model with a 0.12° (13.2 km) grid spacing that has a parametrization of subgrid-scale convective clouds and precipitation. The 13.2 km simulation underestimates precipitation intensity, produces rainfall too frequently, and shows evident biases in reproducing the diurnal cycle of precipitation and low-level wind fields. In comparison, the CPM shows significant improvements in the spatial distribution of precipitation intensity, although it overestimates the intensity magnitude and has a wet bias over central eastern China. The diurnal cycle of precipitation over Mei-yu region, southern China and the eastern periphery of the Tibetan Plateau, as well as the diurnal cycle of low-level winds over both the Mei-yu region and southern China are better simulated by the CPM. Over the Mei-yu region, in both simulations and observations, the local atmospheric instability in the afternoon is favorable for upward motion and rainfall. The CPM receives more sensible heat flux from the surface, has a stronger upward motion, and overestimates water vapor convergence based on moisture budget diagnosis. All these processes help explain the excessive late afternoon rainfall over the Mei-yu region in the CPM simulation.

The influence of the nozzle-exit boundary-layer profile on high-subsonic jets is investigated by performing compressible large-eddy simulations (LES) for three isothermal jets at a Mach number of 0.9 and a diameter-based Reynolds number of $5\\times 10^{4}$ , and by conducting linear stability analyses from the mean-flow fields. At the exit section of a pipe nozzle, the jets exhibit boundary layers of momentum thickness of approximately 2.8 % of the nozzle radius and a peak value of turbulence intensity of 6 %. The boundary-layer shape factors, however, vary and are equal to 2.29, 1.96 and 1.71. The LES flow and sound fields differ significantly between the first jet with a laminar mean exit velocity profile and the two others with transitional profiles. They are close to each other in these two cases, suggesting that similar results would also be obtained for a jet with a turbulent profile. For the two jets with non-laminar profiles, the instability waves in the near-nozzle region emerge at higher frequencies, the mixing layers spread more slowly and contain weaker low-frequency velocity fluctuations and the noise levels in the acoustic field are lower by 2–3 dB compared to the laminar case. These trends can be explained by the linear stability analyses. For the laminar boundary-layer profile, the initial shear-layer instability waves are most strongly amplified at a momentum-thickness-based Strouhal number $St_{\\unicode[STIX]{x1D703}}=0.018$ , which is very similar to the value obtained downstream in the mixing-layer velocity profiles. For the transitional profiles, on the contrary, they predominantly grow at higher Strouhal numbers, around $St_{\\unicode[STIX]{x1D703}}=0.026$ and 0.032, respectively. As a consequence, the instability waves rapidly vanish during the boundary-layer/shear-layer transition in the latter cases, but continue to grow over a large distance from the nozzle in the former case, leading to persistent large-scale coherent structures in the mixing layers for the jet with a laminar exit velocity profile.