Reduction In Velocity Research Articles

Physiological Targets for Orthostatic Hypotension: Improving Nonpharmacological Interventions in Patients with Orthostatic Cerebral Hypoperfusion.

Orthostatic hypotension (OH) is a form of orthostatic intolerance (OI) and a key physiological indicator of autonomic dysfunction that is associated with an increased risk of major cerebrocardiovascular events. Symptoms of cerebral hypoperfusion have been reported in patients with OH, which worsens symptoms and increases the risk of syncope. Since pharmacological interventions increase blood pressure (BP) independent of posture and do not restore normal baroreflex control, nonpharmacological treatments are considered the foundation of OH management. While reductions in cerebral blood flow velocity (CBFv) during orthostatic stress are associated with a decrease in end-tidal CO2 (EtCO2) and hypocapnia in patients with OI, their contribution to the severity of OH is not well understood. These measures have been physiological targets in a wide variety of biofeedback interventions. This study explored the relationship between cardiovascular autonomic control, EtCO2 and cerebral hypoperfusion in patients (N = 72) referred for OI. Patients with systolic OH were more likely to be male, older, demonstrate reduced adrenal and vagal baroreflex sensitivity, and reduced cardiovagal control during head-up tilt (HUT) than patients without systolic OH. Greater reduction in CBFv during HUT was associated with a larger reduction in ETCO2 and systolic BP during HUT. While deficits in cardiovascular autonomic control played a more important role in systolic OH, reduced EtCO2 was a major contributor to orthostatic cerebral hypoperfusion. These findings suggest that biofeedback treatments targeting both the autonomic nervous system and EtCO2 should be part of nonpharmacological interventions complementing the standard of care in OH patients with symptoms of cerebral hypoperfusion.

Fall prediction, control, and recovery of quadruped robots

When legged robots perform complex tasks in unstructured environments, falls are inevitable due to unknown external disturbances. However, current research mainly focuses on the locomotion control of legged robots without falling. This paper proposes a comprehensive decision-making and control framework to address the falling over of quadruped robots. First, a capturability-based fall prediction algorithm is derived for planar single-contact and 3D multi-contact locomotion with a predefined gait sequence. For safe fall control, a novel contact-implicit trajectory optimization method is proposed to generate both state and input trajectories and contact mode sequences. Specifically, incorporating uncertainty into the system and terrain models enables mitigating the non-smoothness of contact dynamics while improving the robustness of the resulting trajectories. Furthermore, a model-free deep reinforcement learning-based approach is presented to achieve fall recovery after the robot completes a fall. Experimental results demonstrate that the proposed fall prediction algorithm accurately predicts robot falls with up to 95% accuracy approximately 395ms in advance. Compared to classical locomotion controllers, which often struggle to maintain balance under significant pushes or terrain perturbations, the presented framework can autonomously switch to the fall controller approximately 0.06s after the perturbation, effectively preventing falls or achieving recovery with a threefold reduction in touchdown impact velocity. These findings highlight the effectiveness of the proposed framework in enhancing the stability and safety of legged robots in unstructured environments.

Flow Diversion Effect in a Saphenous Vein Graft Aneurysm Using a Double-Layer Micromesh Stent: A Case Report.

A double-layer micromesh stent is designed for the treatment of carotid artery stenosis that has been reported to potentially provide a flow diversion effect. However, the actual flow diversion effect of stents remains unclear. Here, we present a case of a growing saphenous vein graft (SVG) aneurysm treated with the placement of the double-layer micromesh stent using its flow diversion effect. A 66-year-old woman, who underwent high-flow bypass using a SVG for a blister-like internal carotid artery aneurysm 13 years earlier at our institute, was referred to our hospital with a pulsatile cervical mass. Magnetic resonance angiography showed a 9-mm aneurysm on the left SVG, although the aneurysm was a small pouch 4 years earlier. Digital subtracted angiography demonstrated a 9.4 × 8.3-mm aneurysm from the SVG at the auricular level. Because the diameter of the graft was larger than that of the available flow diverter stents in Japan, we decided to place the double-layer micromesh stent (CASPER RX, 7 × 25 mm MicroVention) using its flow diversion effect. Computational fluid dynamics analysis before and after stent deployment showed a significant reduction in the average flow velocity and wall shear stress in the aneurysm, indicating actual flow diversion. An angiogram 2 months postoperatively showed complete obliteration of the aneurysm. Obliteration of the saphenous vein aneurysm was achieved because of the flow diversion effect of the double-layer micromesh stent. The stents might be a feasible alternative for treating cervical carotid aneurysms.

Exploring the influence of vegetated mid-channel bar on flow and turbulence in bifurcated channels: An experimental approach

The evolution of fluvial systems is greatly impacted by mid-channel bars, a typical morphodynamic process in natural rivers. Sometimes, the growth of vegetation over these bars complicates the morphological behaviour by interacting with the flow. It is therefore necessary to have a fundamental interpretation of the flow-turbulence structure around the mid-bar in presence of vegetation cover in order to understand braiding dynamics, still studies in this area are scarce. The present study investigates the process-form-vegetation-interaction through experimental investigation at a flume scale mid-channel bar model with different natural vegetation cover arrangements (paddy, leafy, and rigid stem). The flow-turbulence behaviour has been observed through the bifurcated channel using the three-dimensional Acoustic Doppler Velocimeter (ADV). Results showed that the longitudinal velocity component varies with the different vegetation cover, and it was highest with leafy vegetation (about 32%). Similarly, the Reynolds Stress and Turbulence Intensity were also observed to be higher in case of leafy vegetation. A unique pattern of flow-turbulence parameters was observed near the bar level, the lower canopy level, and the upper canopy level. Moreover, it was found that vegetation structure and its flexible nature influence both longitudinal velocity reduction and momentum transfer at and over the canopy, as well as the thickness of the shear layer region.

Kinetic Theory of Motility Induced Phase Separation for Active Brownian Particles.

When two active Brownian particles collide, they slide along each other until they can continue their free motion. For persistence lengths much larger than the particle diameter, the directors do not change, but the collision can be modeled as producing a net displacement on the particles compared to their free motion in the absence of the encounter. With these elements, a Boltzmann-Enskog-like kinetic theory is built. A linear stability analysis of the homogeneous state predicts a density instability resulting from the effective velocity reduction of tagged particles predicted by the theory.

Modelled effectiveness of NbS in reducing disaster risk: Evidence from the OPERANDUM project

The use of nature-based solutions (NbS) to address the risks posed by hydro-meteorological hazards have not yet become part of the mainstream policy response, and one of the main reasons cited for this, is the lack of evidence that they can effectively reduce disaster risk. This paper addresses this issue, by providing model-based evidence from five European case studies which demonstrate the effectiveness of five different NbS in reducing the magnitude of the hazard and thus risk, in present-day and possible future climates. In OAL-Austria, the hazard is a deep-seated landslide, and the NbS analysed is afforestation. Modelling results show that in today's climate and a landcover scenario of mature forest, a reduction in landslide velocity of 27.6 % could be achieved. In OAL-Germany, the hazard is river flooding and the NbS analysed is managed grazing with removal of woody vegetation. Modelling results show that the NbS could potentially reduce maximum flood water depth in the near-future (2031–2060) and far-future (2070–2099), by 0.036 m and 0.155 m, respectively. In OAL-Greece, the hazard is river flooding, and the NbS is upscaled natural storage reservoirs. Modelling results show that in a possible future climate the upscaled NbS show most potential in reducing the total flooded area by up to 1.26 km2. In OAL-Ireland, the hazard is surface and river flooding, and the NbS is green roofs. Results from a modelled upscaling analysis under two different climate scenarios show that both maximum flood water depth, and total flooded area were able to be reduced. In OAL-UK, the hazard is shallow landslides, and the NbS is high-density planting of two different tree species. Modelling results under two different climate scenarios show that both tree species were able to improve slope stability, and that this increased over time as the NbS matured. The significance of these results is discussed within the context of the performance of the NbS over time, to different magnitude events, impact with stakeholders in engendering wider support for the adoption of the NbS in the OALs, and the uncertainty in the modelling analyses.

Peristaltic transport of diethylene glycol-based magnesium aluminate nanofluid under the effects of viscous dissipation and Hall current

ABSTRACT The fundamental importance of peristaltic phenomena in numerous biological systems, including dialysis, heart-lung machines, urine transportation, invertebrate locomotion, and the passage of gallbladder bile into the intestines, persuaded scientists to investigate the different aspects of it over the past few years. In addition, peristaltic pumping is an important consideration in industrial processes including, roller pumps used for the transport of sanitary materials, finger pumps, cell separation, and endoscopes. Keeping such inspirational applications in mind, the present investigation is dedicated to exploring the peristaltic transport of a Cross-magneto nanofluid through a curved geometry in the presence of heat transfer. The inspection of the heat transfer is conducted by utilizing variable viscosity and ohmic heating aspects. This study also retains the characteristics of viscous dissipation, heat generation/absorption, and thermal conductivity of nanofluids. Modeling of the 2D, incompressible Cross nanofluid with peristaltic movement is carried out using a curvilinear coordinate system. The basic equations of the problem are mPodeled in the light of physical laws and then simplified by adopting the lubrication theory. The solutions of the resulting nonlinear system are computed numerically. The outcomes of the related flow parameters on the nanofluid’s temperature, pressure gradient, velocity distribution, heat transfer, streamlines pattern, and stresses at the wall are discussed through graphs. The graphical results depict that the rates of heat transfer are augmented by increasing the curvature parameter, Hartmann number, and nanoparticles’ volume fraction while decreasing the Hall parameter and temperature-dependent viscosity parameter. Moreover, the nanofluid’s temperature increases by improving the values of the heat generation parameter, whereas it decreases for the Hall parameter. Furthermore, a reduction in the axial velocity occurs near the center of the channel, when Hartmann number attains higher values.

Effects of wind shear and thrust coefficient on the induction zone of a porous disk: A wind tunnel study

AbstractNeglecting the velocity reduction in the induction zone of wind turbines can lead to overestimates of power production predictions, and, thus, of the annual energy production for a wind farm. An experimental study on the induction zone associated with wind turbine operations is performed in the boundary‐layer test section of the BLAST wind tunnel at UT Dallas using stereo particle image velocimetry. This experiment provides a detailed quantification of the wind speed decrease associated with the induction zone for two different incoming flows, namely, uniform flow and boundary layer flow. Operations of wind turbines in different regions of the power curve are modeled in the wind tunnel environment with two porous disks with a solidity of 50.4% and 32.3%, which correspond to thrust coefficients of 0.71 and 0.63, respectively. The porous disks are designed to approximate the wake velocity profiles previously measured for utility‐scale wind turbines through scanning wind LiDARs. The results show that the streamwise velocity at one rotor diameter upwind of both disks decreases 1% more for the boundary layer flow than for the uniform flow. Further, the effect of shear in front of the disk with a higher thrust coefficient can be observed until 1.75 rotor diameter upwind of the disk, whereas for the disk with a lower thrust coefficient, the effect of shear becomes negligible at 1.25 rotor diameter upwind. It is found that at one rotor diameter upwind, for both incoming flows, the disk having a higher thrust coefficient has 2% more velocity reduction than the lower‐thrust‐coefficient disk. The results suggest that the variability in wind shear and rotor thrust coefficient, which is encountered during typical operations of wind turbines, should be considered for the development of improved models for predictions of the rotor induction zone, the respective cumulative effects in the presence of multiple turbines, namely, wind farm blockage, and more accurate predictions of wind farm power capture.

Decreasing the blood flow of non-compressible intra-abdominal organs with non-invasive transcutaneous electrical stimulation

Non-invasive neuromodulation of non-compressible internal organs has significant potential for internal organ bleeding and blood-shift in aero/space medicine. The present study aims to investigate the potential influences of the non-invasive transcutaneous electrical nerve stimulation (TENS) on multiple non-compressible internal organs’ blood flow. Porcine animal model (n = 8) was randomized for a total of 48 neuromodulation sessions with two different TENS stimulation frequencies (80 Hz, 10 Hz) and a placebo stimulation. A combination of two different electrode configurations (Abdominal-only or Abdominal and hind limb) were also performed. Intraarterial blood flow measurements were taken during pre and post-stimulation periods at the left renal artery, common hepatic artery, and left coronary artery. Intracranial, and extracranial arterial blood flows were also assessed with digital subtraction angiography. TENS with abdominal-only electrode configurations at 10 Hz demonstrated significant reductions in average peak blood flow velocity (APV) of the common hepatic artery (p = 0.0233) and renal arteries (p = 0.0493). Arterial pressures (p = 0.0221) were also significantly lower when renal APV was reduced. The outcome of the present study emphasises the potential use of TENS in decreasing the blood flow of non-compressible internal organs when the correct combination of electrodes configuration and frequency is used.

Increases in Central Arterial Stiffness and Reductions in Diastolic Velocity in the Large Cerebral Arteries are Associated with Age-Related Decline in Cerebral Blood Flow

Background: Advanced aging is characterized by a reduction in cerebral blood flow (CBF) and an increase in central arterial stiffness. Increased central arterial stiffness results in reduced Windkessel effects and augmented pulsatile arterial blood pressure and CBF. These changes are detrimental to small cerebral blood vessels because of increases in biomechanical stresses associated with the augmented pulsatile arterial blood pressure and CBF. Purpose: To examine the associations of central arterial stiffness with cerebral hemodynamics and age-related reductions in CBF. Methods: 171 healthy subjects (20-81 yrs, 63% F) underwent color-coded duplex ultrasonography of the left and right internal carotid (ICA) and vertebral artery (VA) to characterize individual artery blood flow (BF), velocity, pulsatility, and CBF. Structural Magnetic Resonance Imaging (MRI) was used to measure total brain tissue volume (TBV). Carotid β-stiffness and carotid-femoral pulse wave velocity (cfPWV) were measured via applanation tonometry to assess central artery stiffness. Data: Age was negatively associated with global CBF (r = -0.425, p < 0.001), and positively with cfPWV (r = 0.701, p < 0.001), and carotid β-stiffness (r = 0.660, p < 0.001). Arterial stiffness was negative associated with ICA diastolic velocity (r = -0.280, p < 0.001; r = -0.259, p < 0.001) and VA diastolic velocity (r = -0.280, p < 0.001; r = -0.248, p = 0.001) controlling for sex, body mass index (BMI), education, and TBV. Carotid β-stiffness moderated indirect effect between age and CBF through ICA diastolic velocity (index of moderated-mediation -0.47 ± 0.13, [-0.74,-0.23]. cfPWV did not moderate the indirect effect between age and CBF through ICA diastolic velocity (index of moderated-mediation -0.36 ± 0.18, [-0.69, 0.03]. The indirect effect of age on CBF through VA diastolic velocity was not moderated by cfPWV (0.03 ± 0.09, [-0.13, 0.23]) or carotid β-stiffness (-0.17 ± 0.09, [-0.33, 0.01]). Conclusions: Age-related decline in CBF is mediated by the decreases in ICA blood flow diastolic velocity, and this relationship was moderated by carotid β-stiffness. This data suggests that increases in central arterial stiffness and reductions in CBF diastolic velocity in the large cerebral arteries likely plays an important role in age-related decline in CBF. This study was supported by NIH R01HL102457-01 and NIH R01AG033106-01. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Prefrontal cortex activity and functional organisation in dual-task ocular pursuit is affected by concurrent upper limb movement.

Tracking a moving object with the eyes seems like a simple task but involves areas of prefrontal cortex (PFC) associated with attention, working memory and prediction. Increasing the demand on these processes with secondary tasks can affect eye movements and/or perceptual judgments. This is particularly evident in chronic or acute neurological conditions such as Alzheimer's disease or mild traumatic brain injury. Here, we combined near infrared spectroscopy and video-oculography to examine the effects of concurrent upper limb movement, which provides additional afference and efference that facilitates tracking of a moving object, in a novel dual-task pursuit protocol. We confirmed the expected effects on judgement accuracy in the primary and secondary tasks, as well as a reduction in eye velocity when the moving object was occluded. Although there was limited evidence of oculo-manual facilitation on behavioural measures, performing concurrent upper limb movement did result in lower activity in left medial PFC, as well as a change in PFC network organisation, which was shown by Graph analysis to be locally and globally more efficient. These findings extend upon previous work by showing how PFC is functionally organised to support eye-hand coordination when task demands more closely replicate daily activities.

Seismic Evidence for Crustal Magmatic Intrusion Beneath the Southern Part of the Eastern North American Margin

AbstractThe southern portion of the eastern North American margin (SENAM) is an archetypical volcanic passive margin formed during Mesozoic rifting. How past magmatic events affect the evolution of the SENAM remains an open question of fundamental importance. To better understand this question, here we construct a high‐resolution 3‐D crustal velocity model from the oceanic side to the continental interior with a combination of multimodal dispersion inversion and full‐waveform ambient noise tomography. Our new model reveals an oceanic‐continental transitional crust over a short horizonal distance of 100–150 km across the SENAM, with a local‐scale lower‐than‐surrounding velocity anomaly directly beneath the transitional crust. Furthermore, the new model shows three intra‐crustal higher‐than‐average velocity anomalies beneath the SENAM continent. We suggest that the magmatism assisted the Mesozoic rifting process to form the narrow ocean‐continent transitional crust along the coastline. The underplating of magma beneath the transitional crust led to a reduction of seismic velocity of the uppermost mantle. In addition, it is probable that the emplacement of the Central Atlantic Magmatic Province caused widespread magmatic intrusions within the continental crust of the SENAM, which were later solidified into intra‐crustal high‐velocity plutons. Our findings provide new insights into crustal modification history at the passive margin.

Electroosmotic flow in graphene nanochannels considering steric effects

Graphene nanochannels are excellent channels for electroosmotic flow (EOF) due to their larger slip length. In this study, the fully developed EOF in graphene nanochannels is investigated numerically, where the influence of surface charge mobility on the Navier-slip boundary conditions and the influence of steric effect on the electric potential distribution are considered. In addition, an analytical solution is provided for the scenario with low zeta potential. Detailed investigations are conducted on the impact of slip length, surface charge density, surface charge mobility, effective ion size, solution concentration, and channel height on velocity profiles. The findings indicate that the velocity increases with slip length, surface charge density, and effective ion size. Yet, accounting for surface charge mobility (αs = 0.815) leads to a reduction in slip velocity. It is noteworthy that our investigation focuses on quantifying the velocity decline due to surface charge mobility, as well as the velocity enhancement resulting from the steric effect. By adjusting parameters, such as channel height, bare slip length, and solution concentration, we achieve a maximum velocity increase of approximately 48%. These insights are valuable for optimizing the design of efficient electro-osmotic pumping systems.

Clinical Assessment of the Nystagmus Fixation Suppression Test: An Experimental Study.

Assessment of nystagmus fixation suppression can be used as an additional diagnostic tool for patients with an acute vestibular syndrome to distinguish between a central or peripheral cause. We investigated the ability of physicians to detect fixation suppression using a nystagmus simulation model. We used a nystagmus simulator to measure the accuracy of the nystagmus fixation suppression test. Fixation suppression was assessed randomly in 6170 trials by 20 otorhinolaryngologists and neurologists, segregated into 2 groups based on their neurootological experience, a beginner and an experienced group. The simulator presented random nystagmus slow velocity (SPV) reductions and presented 3 conditions with either changed nystagmus frequency, amplitude, or both. The cutoff for the discernment of fixation suppression ranged from 1.2 to 14°/s nystagmus velocity difference. The more intense the baseline nystagmus was, the more difficult was the detection of fixation suppression. There was not significant difference (P >.05) in the cutoff values in the experts group compared to the novices for all 3 different conditions. Both, novices and experts, detected frequency changes easier than differences of the nystagmus amplitude. Test sensitivity was very low (19%-65%) for discernment of small nystagmus velocity differences of <2°/s by experts. In our study, there was no difference between experts and novices in detection of nystagmus suppression by visual fixation. The examiners could only detect large suppression effects at low-intensity baseline nystagmus. Overall, the sensitivity and accuracy of a clinical fixation suppression test is low and the assistance with a video-oculography device is highly recommended.

SELECTIVE SODIUM PUMP INHIBITOR CALIX[4]ARENE C-1130 INCREASES CONCENTRATION OF Ca IONS IN SMOOTH MUSCLE CELLS

Aim. This work aimed to determine the biochemical regularities of calix[4]arene C-1130 effect on the activity of Nа+,К+-АТРase and Са2+ level in PM of smooth muscle cells (SMCs). Methods. Calix[4]arene C-1130 was synthesized and characterized in the Institute of Organic Chemistry of NAS of Ukraine. Biochemical studies were carried out in the Department of Muscle Biochemistry of Palladin Institute of Biochemistry, NAS of Ukraine. The experiments were performed on a suspension of myometrial cells and the PM fraction. Determination of the intracellular Са2+ concentration was done by confocal microscopy. The hydrodynamic diameter of myocytes was determined by dynamic light scattering. Results. We have studied the dependence of the activity of Nа+,К+-АТРase of PM on the concentration of Mg ions and ATP at different concentrations of calix[4]arene C-1130. The affinities of Nа+,К+-АТРase for ATP and Mg ions remained unaffected by the presence of calix[4]arene C-1130. However, a notable reduction in the initial maximum velocity of enzymatic ATP hydrolysis was observed. Overall, it indicates a non-competitive mechanism of inhibition of Nа+,К+-АТРase by C-1130. Confocal microscopy analysis showed that calix[4]arene C-1130 elevates Са2+ concentration within myometrial myocytes. Photon-correlation spectroscopy revealed that C-1130 reduces the effective hydrodynamic diameter of SMCs. Conclusions. We have shown that calix[4]arene C-1130 does not affect the activation coefficient for Mg ions and the apparent Michaelis constant Кm for ATP, but it reduces the maximum initial velocity Vmax of the ATP hydrolysis reaction. Thus, calix[4]arene C-1130 acts as a complete non-competitive inhibitor of Nа+,К+-АТРase of PM.

Numerical analysis for the design of a central air conditioning system for center of excellence

The temperature of the towing tank floor of the Center of Excellence in Marine and Offshore Engineering, Rivers State University needs regulation due to the high level of humidity during experiments. Since vapor evaporates from the towing-tank liquid column, the need for central air conditioning is timely. With the temperature regulated, it will help enhance the comfort of the students and improve the working condition of the staff and equipment. This is achieved by conducting a cooling load analysis, consistent with ASHRAE Guidelines, on the floor plan of the Laboratory building that provided useful information on the proper selection and sizing of fit-for-purpose air-conditioning equipment. Analysis revealed a total sensible and latent heat load of 59195.74 W with system capacity of 16.91TR (tons). Duct design utilizing the Velocity Reduction method resulted in a main supply duct length of 57m and flow are of 0.72m2 incorporating four branched ducts measuring 6m each in length and flow area of 1.05m2

Phenylephrine alters phase synchronization between cerebral blood velocity and blood pressure in ME/CFS with orthostatic intolerance.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) with orthostatic intolerance (OI) is characterized by neurocognitive deficits perhaps related to upright hypocapnia and loss of cerebral autoregulation (CA). We performed N-back neurocognition testing and calculated the phase synchronization index (PhSI) between arterial pressure (AP) and cerebral blood velocity (CBV) as a time-dependent measurement of cerebral autoregulation in 11 control (mean age = 24.1 yr) and 15 patients with ME/CFS (mean age = 21.8 yr). All patients with ME/CFS had postural tachycardia syndrome (POTS). A 10-min 60° head-up tilt (HUT) significantly increased heart rate (109.4 ± 3.9 vs. 77.2 ± 1.6 beats/min, P < 0.05) and respiratory rate (20.9 ± 1.7 vs. 14.2 ± 1.2 breaths/min, P < 0.05) and decreased end-tidal CO2 (ETCO2; 33.9 ± 1.1 vs. 42.8 ± 1.2 Torr, P < 0.05) in ME/CFS versus control. In ME/CFS, HUT significantly decreased CBV compared with control (-22.5% vs. -8.7%, P < 0.005). To mitigate the orthostatic CBV reduction, we administered supplemental CO2, phenylephrine, and acetazolamide and performed N-back testing supine and during HUT. Only phenylephrine corrected the orthostatic decrease in neurocognition by reverting % correct n = 4 N-back during HUT in ME/CFS similar to control (ME/CFS = 38.5 ± 5.5 vs. ME/CFS + PE= 65.6 ± 5.7 vs. Control 56.9 ± 7.5). HUT in ME/CFS resulted in increased PhSI values indicating decreased CA. Although CO2 and acetazolamide had no effect on PhSI in ME/CFS, phenylephrine caused a significant reduction in PhSI (ME/CFS = 0.80 ± 0.03 vs. ME/CFS + PE= 0.69 ± 0.04, P < 0.05) and improved cerebral autoregulation. Thus, PE improved neurocognitive function in patients with ME/CFS, perhaps related to improved neurovascular coupling, cerebral autoregulation, and maintenance of CBV.NEW & NOTEWORTHY We evaluated cognitive function before and after CO2, acetazolamide, and phenylephrine, which mitigate orthostatic reductions in cerebral blood velocity. Neither CO2 nor acetazolamide affected N-back testing (% correct answers) during an orthostatic challenge. Only phenylephrine improved upright N-back performance in ME/CFS, as it both blocked hyperventilation and increased CO2 significantly compared with those untreated. And only phenylephrine resulted in improved PSI values in both ME/CFS and control while upright, suggesting improved cerebral autoregulation.

Study of the effect of spur dikes on beach protection based on physical model experiment

The Qiantang River is a typical strong tide estuary, the world-famous tidal bore have huge turbulent energy and causes damage to the sea wall. Spur dike is an important engineering to prevent the seawall foundation from tidal bore. But the tidal bore occurs at the low tide level, strong turbulence, high flow velocity, water level rises sharply. The spur dike height, length, inclination angle need to be determined by physical model according to the specific bore dynamic conditions. In the tests, the fixed-bed model was used to study the tidal current velocity reduction rate and region, the falling current circulation characteristics in dike field. The movable-bed model test is used to study the effect of each test on protecting the beach. This physical model study reveals the rule of spur dike influence on tidal bore dynamics so the effect of spur dike on protecting the beach is clear.

Investigation of Car following and Lane Changing Behavior in Diverging Areas of Tunnel–Interchange Connecting Sections Based on Driving Simulation

Tunnel–interchange connecting sections pose significant safety challenges on mountainous expressways due to their high incidence of accidents. Improving road safety necessitates a comprehensive understanding of driver behavior in such areas. This study explores the influences of road characteristics, signage information volume, and traffic conditions on drivers’ car-following and lane-changing behavior in tunnel–interchange diverging areas. Utilizing driving data from 25 subjects of 72 simulated road models, driving performance is assessed using the Friedman rank test and multivariate variance analysis. The results highlight the significant influence of both connection distance and signage information load on driving behavior. In tunnel–interchange scenarios, the reduction in velocity increased by 62.61%, and speed variability surged by 61.11%, indicating potential adverse effects on driving stability due to the environmental transitions. Decreased connection distances are associated with reduced lane-changing durations, larger steering angles, and increased failure rates. Furthermore, every two units of increase in signage information leads to a 13.16% rise in maximum deceleration and a 5% increase in time headway. Notably, the signage information volume shows a significant interaction with connection distance (F &gt; 1.60, p &lt; 0.045) for most car-following indicators. Hence, the study recommends a maximum connection distance of 700 m and signage information not exceeding nine units for optimal safety and stability.

Seismic evidence for melt-rich lithosphere-asthenosphere boundary beneath young slab at Cascadia

The Lithosphere-Asthenosphere Boundary (LAB) beneath oceanic plates is generally imaged as a sharp seismic velocity reduction, suggesting the presence of partial melts. However, the fate of a melt-rich LAB is unclear after these plates descend into the mantle at subduction zones. Recent geophysical studies suggest its persistence with down-going old and cold slabs, but whether or not it is commonly present remains unclear, especially for young and warm slabs such as in the Cascadia subduction zone. Here we provide evidence for its presence at Cascadia in the form of a large (9.8±\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\pm$$\\end{document}1.5%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document}) decrease in shear-wave velocity over a very small (<3 km) depth interval. Similarly large and sharp seismic velocity reduction at the bottom of both old and young slabs, as well as along the base of oceanic plates before subduction, possibly represents widespread presence of melts. The melt-rich sub-slab LAB may strongly influence subduction dynamics and viscoelastic earthquake cycles.