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In this lecture, some aspects of vestibular pathology propedeutics are highlighted. The necessity of careful vestibulosensory reactions analysis by different physicians (ENT specialist, neurologist, internist, general practitioner) is emphasized. Main patients’ complaints (vertigo and unsteadiness) are distinguished between. Special attention is paid to the classification of these vestibulosensory reactions on their duration and periodicity. The terms (sickness itself and balance disorders that may be concomitant symptoms of kinetosis) are clearly defined. Theories and clinical manifestations of sickness syndromes and motion sickness are described in details. Clinical variants of peripheral and central vestibular dysfunction are analyzed. The importance of computerized technics of vestibulometry (electrooculography, video oculography and computer dynamic posturography) in order to make a topic diagnosis of vestibular dysfunction and to assess visual-vestibular interaction in sickness is emphasized.

The roles of nanoparticles and geometric effects are incredible in nanotechnology. The significant prospective of nanoparticles can be found in the manufacturing of machineries, heating/cooling of nuclear reactors, chemical and thermal engineering, mechanical and aerodynamics, etc. Thus, the current model study is performed for the heat transport mechanism in a newly engineered ternary nanofluid model for sinusoidal surface. The conventional model was updated via influences of ternary nanoparticles, transient phenomena, radiation and heat generation effects, convective and thermal slip impacts. The primary governing laws are reduced into the desired model form via transient similarity expressions and ternary nanoliquid models. Afterward, the shooting scheme supportive by RK technique is endorsed for physical configuration of the model dynamics under multiple ranges of the parameters. The outcomes revealed that both the components of velocity showed different behaviors for nodal and saddle points against the nodal-saddle parameter s1 that is, in the saddle case the velocity is decreased while in the nodal case its value is boosted when the value of s1 is slightly increased. Further, the temperature of the fluid is increased when Q1 and Rd varied from 0.1 to 0.7. Further, the skin friction augments from 119.5% to 121.55%, 121.54% to 129.15% when s1 and st vary from 0.1 to 0.5, respectively. The Nusselt number improved from 12.2124% to 12.218% (for nanoparticles concentration), 11.9109% to 11.7996% (for heating source Q1 from 0.2 to 0.5) and increased from 22.3815% to 47.5804% (for Biot number variations from 0.2 to 0.5). Hence, the Biot number highly contributes to the heat transfer rate than other parameters. [ABSTRACT FROM AUTHOR]

Shock wave boundary/layer interactions (SWBLIs) are critical in high-speed aerodynamic flows, particularly within supersonic regimes, where unsteady dynamics can induce structural fatigue and degrade vehicle performance. Conventional measurement techniques, such as pressure-sensitive paint (PSP), face limitations in frequency response, calibration complexity, and intrusive instrumentation. Similarly, MEMS-based sensors, like Kulite® sensors, present challenges in terms of intrusiveness, cost, and integration complexity. This study presents a flexible, lightweight polyvinylidene fluoride (PVDF) piezoelectric sensor array designed for high-resolution wall-pressure measurements in SWBLI research. The primary objective is to optimize low-frequency pressure fluctuation detection, addressing SWBLI's need for accurate, real-time measurements of low-frequency unsteadiness. Fabricated using a double-sided screen-printing technique, this sensor array is low-cost, flexible, and provides stable, high-sensitivity data. Finite Element Method (FEM) simulations indicate that the sensor structure also has potential for high-frequency responses, behaving as a high-pass filter with minimal signal attenuation up to 300 kHz, although the current study's experimental testing is focused on low-frequency calibration and validation. A custom low-frequency sound pressure setup was used to calibrate the PVDF sensor array, ensuring uniform pressure distribution across sensor elements. Wind tunnel tests at Mach 2 verified the PVDF sensor's ability to capture pressure fluctuations and unsteady behaviors consistent with those recorded by Kulite sensors. The findings suggest that PVDF sensors are promising alternatives for capturing low-frequency disturbances and intricate flow structures in advanced aerodynamic research, with high-frequency performance to be further explored in future work. [ABSTRACT FROM AUTHOR]

Background and Purpose: Basilar artery (BA) tortuosity is closely associated with posterior circulation infarction (PCI) and dizziness/unsteadiness. This study aims to determine the relationship between BA tortuosity and the outcome of dizziness and unsteadiness in PCI patients. Method: This study prospectively recruited PCI patients presenting with dizziness and unsteadiness. BA tortuosity was diagnosed based on Smoker's criteria. The BA tortuosity index (BATI) was measured from magnetic resonance angiography (MRA) images. Posterior circulation was divided into proximal (medulla oblongata and posterior inferior cerebellar), middle, and distal territories. Symptoms, risk of falls, and quality of life were followed up in 3 months after stroke. Logistic regression was used to identify possible factors associated with the persistence of dizziness and unsteadiness. Results: Among 182 PCI patients presenting with dizziness and unsteadiness, 97 (53.3%) had BA tortuosity, including 19 (10.4%) with moderate‐to‐severe BA tortuosity. At the 3‐month follow‐up, 58 (31.9%) patients continued to experience dizziness and unsteadiness, with significantly decreased quality of life and a high risk of falls. Binary logistic regression analysis identified moderate‐to‐severe BA tortuosity (OR, 4.474; 95% CI, 1.591–12.579; p = 0.004) and lesions involving the proximal posterior circulation territory (OR, 2.146; 95% CI, 1.097–4.199; p = 0.026) as risk factors for persistent dizziness and unsteadiness after PCI, while thrombolysis (OR, 0.280; 95% CI, 0.079–0.992; p = 0.049) as a protective factor. BATI (OR, 1.072; 95% CI, 1.028–1.119; p = 0.001) was also independently associated with dizziness and unsteadiness after PCI. Conclusion: Prominent BA tortuosity increases the risk of persistent dizziness and unsteadiness after PCI, leading to a high risk of falls and decreased quality of life. This warrants more attention in clinical practice. [ABSTRACT FROM AUTHOR]

A common denominator between conical-symmetry and conical shock interaction is the spanwise pressure gradient, which perform more non-uniformity and its interaction flow is more complicated than the spanwise-homogeneous planar shock wave. Recent advances in conical-symmetry and conical shock interactions with turbulent boundary layer are reviewed in specific areas: (i) quasi-conical swept interactions due to compression ramps and sharp fins, (ii) impinging conical shock wave with interactions of plate wall, (iii) laminar double cone interactions with consideration of real-gas effects. Substantial success has been achieved in describing the phenomena of the time averaged and instantaneous flow features and the low-frequency unsteadiness, including correlations and coherent structures in the separation bubble, through complementary experimental and numerical studies of swept shock interactions. All available observations are here scrutinized to infer underlying mechanisms of interactions in conical flow, and provide theoretical foundation and hints for fluidic control techniques. Comparison with high-fidelity direct numerical simulations is used to quantified the uncertainty of RANS turbulence models in complex interactions. Regarding heat transfer, extensive studies of hypersonic flow over double cone geometries have shown that those can be predicted with reasonable accuracy, even in the presence of high-temperature effects.

The unsteady three-dimensional flow of nanofluid over a stretching surface in the presence of a magnetic field and thermal radiation are investigated. Zero nanoparticle flux at the wall has been considered. Buongiorno's model for nanofluid has been used in this study. Employing similarity transformations, the governing partial differential equations are transformed to ordinary ones and the transformed equations are then solved numerically by using the shooting technique with the help of Runge–Kutta method. The computed results are compared with previously reported work and found in excellent agreement. Fluid velocity initially decreases with the increase of the unsteadiness parameter. Temperature and nanoparticle volume fraction both increase with the increase of unsteadiness parameter. Due to the increase of thermal radiation temperature increases, nanoparticle volume fraction decreases initially but increases away from the surface. The effect of the other governing parameters on velocity, temperature and concentration fields are discussed through their graphical representations. Besides, the local skin friction coefficient, local Nusselt number and local Sherwood number are presented through graphs. [ABSTRACT FROM AUTHOR]

To achieve energy conservation and improve ship maneuverability, a new type of collaborative spoiled rudder (CSR) is proposed by absorbing the advantages of existing ship rudders. This study investigates the non-stationary characteristics of the hydrodynamic forces of CSR section in depth, and carries out structural optimization based on numerical simulations. First, the effects of rudder angle and spoiler open angles on the non-stationary characteristics of the hydrodynamic forces of the CSR, and the appropriate maximum value of the spoiler open angle is determined. The results show that the unsteady pulsation amplitude of the hydrodynamic forces of the CSR is directly proportional to the spoiler open angle and inversely proportional to the rudder angle, and the upper limit of the spoiler open angle is set to 30°. Then, the hydrodynamic characteristics of the CSR with different spoiler widths are investigated in further. The maximum lift of the CSR increases as the spoiler width increases. The target lift method is used for efficiency evaluation. The ranges of the favorable rudder angle and the favorable spoiler open angle for different CSR configurations are determined, and the optimal spoiler width is further determined based on the non-stationary characteristics of the hydrodynamic forces. [ABSTRACT FROM AUTHOR]

Here, unsteady boundary layer flow under the action of magnetic effect over a moving stagnation surface has been investigated numerically. This study examines non-Newtonian fluid flow with respect to combined effect of magnetic field, movement of surface and time. Governing equations are dimensionless by applying nondimensional quantities. Then system of coupled ordinary differential equations are obtained by appropriate similarly transformations, in terms of the governing parameter including unsteady parameter (k) , magnetic number (M) , power-law index (n) and three-dimensional parameter (α). Thus, the obtained modelled equations are solved numerically by the shooting technique. The problem's parameters are thoroughly discussed and verified physically and graphically. The obtained results validate to literature result. The two relevant flows' velocity profile's numerical results have been examined. [ABSTRACT FROM AUTHOR]

The association between vestibular pathologies and thyroid hormone disorders has been known for several decades. However, very little information is available on the types of vestibular symptoms that may be affected by altered thyroid hormone levels. The aim of this study was to provide patient data in order to identify statistical associations between vestibular pathologies and thyroid hormone disorders. A retrospective review of the records of 422 patients seen for physiotherapy treatment of vertigo was carried out. Statistical analysis of the data was performed using logistic regression, providing Chi2 and Odds Ratio statistics. Our results show that hypothyroidism statistically significantly increases the expression of certain symptoms, such as vestibular instability and gait disorders, in vestibular pathologies such as Menière's disease or central vertigo. By analyzing patient data, our study provides new evidence of dependence between altered thyroid status and the expression of vestibular pathologies. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of zolpidem and lemborexant on sleep and morning symptoms in patients undergoing type-1 polysomnography for suspected sleep-disordered breathing based on questionnaires and polysomnography results. We enrolled 127 patients (lemborexant: N = 57, zolpidem: N = 25, without hypnotics: N = 45). Rapid eye movement sleep in patients on lemborexant was higher than that in patients without hypnotics (P = 0.02). Frequency of unsteadiness in the morning was higher in patients on zolpidem than that in patients without hypnotics (P = 0.04), which remained after adjustment for potential confounders (P = 0.03). Low-dose lemborexant might be suitable when administered as a single dose during polysomnography. [ABSTRACT FROM AUTHOR]

Abstract An operating 2‐MW wind turbine has been scanned and analysed using 2D computational fluid dynamics (CFD) and blade element momentum (BEM) analysis. The current work illustrates using full‐scale 3D CFD simulations the differences between 2D and 3D simulations and its impact on the local aerofoil vortex shedding frequency. The outcome shows that despite a pressure redistribution and lift change introduced by the blade span and rotation, the vortex shedding frequency remains similar between 2D and 3D thereby validating the novel fatigue calculation method previously proposed.

The article critiques the use of the coefficient of variation of force (CVF) and root mean square of force's first time derivative (RFDRMS) for analyzing force steadiness, proposing Fourier analysis as a more suitable framework. It discusses the limitations of CVF and RFDRMS, highlighting their ambiguity in characterizing force signals, and advocates for the use of discrete Fourier transform (DFT) analysis to provide a clearer and more robust characterization of force signals.

Purpose: To analyze the psychometric properties of the Niigata Questionnaire (NPQ) for use in a European population with persistent postural-perceptual dizziness (PPPD). Methods: Observational study included 140 patients with different vestibular conditions. Construct validity, internal consistency and concurrent validity were analyzed. Intra-class correlation coefficient (ICC), standard error of measurement (SEM) and minimal detectable change (MDC) were calculated. Receiver operating characteristic (ROC) curve was used to test diagnostic values. Results: Of the 140 patients, 47 had a diagnosis of PPPD. Factorial analysis showed a single-factor structure and concurrent validity analysis showed strong correlations with other instruments. Cronbach alpha coefficients of 0.938 for the total score, 0.869 for the standing and gait subscale, 0.803 for the subscale of movements and 0.852 for the visual stimulation subscale were obtained. The reproducibility was substantial except for the standing subscale, which could be considered moderate. For the standing, movement and visual stimulation subscales and for the total score, the SEM was 3.27, 2.41, 2.50 and 6.63, respectively, and the MDC was 6.40, 4.72, 4.91 and 12.99, respectively. The NPQ total score showed an area under the curve (AUC) of 0.661, a sensitivity of 72.34 and a specificity of 55.91 for discriminating between PPPD and other vestibular disorders. Conclusions: The NPQ is feasible for use in a Western population and presents a uni-factorial structure, high internal consistency and strong correlation with other instruments. The reliability can be considered substantial. The NPQ has low accuracy in discriminating between subjects with or without PPPD. [ABSTRACT FROM AUTHOR]

Direct numerical simulations of Mach 6 hypersonic flow over a 34° compression corner subject to steady jet are conducted. Distributions of skin friction coefficient, wall pressure, mean velocity and temperature, boundary layer thickness and Stanton number demonstrate that the flow changes dramatically in the shock wave/turbulent boundary layer interaction area. It is found that the steady jet has no effect on suppressing flow separation unexpectedly, but increases its spatial scale instead. Instantaneous flow structures show that the turbulence amplification can be observed after the application of flow control, and abundant Gortler-like vorticities appear, but the strength of the main shock decreases. Analyzing the wall fluctuating pressure signals using weighted power spectral density, we found an interesting thing. That is, although the low-frequency oscillation phenomenon induced by separation shock is suppressed by the steady jet, wall fluctuating pressure beneath the jet shock is oscillating at a frequency lower than 0.1u∞/δref. Results of coherent and intermittency factor reveal that it is related to the backand- forth movement of the jet shock itself. [ABSTRACT FROM AUTHOR]

Perilymph Fistula (PLF), abnormal communication between the fluid-filled space of the inner ear and the air-filled space of the middle ear, is a significant cause of vestibular and auditory symptoms. This is a retrospective study of 22 cases treated with PLF repair surgery, selected based on our surgical indication. We analyzed the characteristics of these 22 cases and evaluated the efficacy of PLF repair surgery in treating vestibular and auditory symptoms. Cases with antecedent events had significantly shorter intervals before surgery. The postoperative recovery from vestibular symptoms following PLF repair surgery was strikingly rapid, with 82% of cases demonstrating marked improvement within a week, even in chronic cases. Despite the notable absence of a control group in the study, the marked improvements in vestibular symptoms and substantial reductions in Dizziness Handicap Inventory (DHI) scores suggest that the observed benefits are attributable to the surgical intervention. Further, timely surgery showed improvements in hearing, with some benefits also seen in late-stage surgeries. Using the perilymph-specific protein Cochlin-tomoprotein (CTP) as a diagnostic biomarker, we could prove that PLF could be responsible for disequilibrium and related auditory disturbances in these patients. A new hypothesis is proposed that the chronic disequilibrium experienced by many PLF patients is due to enhanced mobility of the utricle and not to endolymphatic hydrops. Further research is needed to fully elucidate PLF's symptoms and treatment efficacy using the surgical indication we developed. [ABSTRACT FROM AUTHOR]

Floating wind turbines are sensitive to hurricane events. Since the turbine rotors are parked and the blades are feathered during hurricanes, the aerodynamic loads due to boundary-layer winds are relatively small compared to the hydrodynamic loads due to sea surface elevations. Hence, accurate modeling of the hurricane wave loads is crucial to ensure the safety of floating wind turbines. During a hurricane, large wave heights with severe flow separation make it inaccurate to use either linear panel method-based models (without nonlinear consideration associated with fluid viscosity) or Morison equation-based models (without unsteady consideration associated with fluid memory). Efforts have been made to advance simulation schemes of hurricane wave loads on spar-type floating wind turbines. This study systematically compares and assesses the efficacy of six hydrodynamic models available in the literature along with a newly proposed model. The ability of these seven hydrodynamic models to capture nonlinear and/or unsteady effects is investigated. As a demonstration example, the wave loads on a spar-type wind turbine are calculated using these seven models to highlight the underlying role of each simulation scheme in accurately acquiring the dynamic responses of this type of offshore floating structure in severe hurricane seas. It is found that the nonlinear viscous term in the Morison equation and hybrid model serves as an important nonlinear damping mechanism. The reduction of the low-frequency wave load and added mass in the modified hybrid model collectively leads to larger displacements compared to those based on the hybrid model. While the displacements based on the stretching method and Rainey's equation are similarly larger than those based on the Morison equation, their nonlinear wave loads are much smaller than those in FNV theory. [ABSTRACT FROM AUTHOR]

Chronic unsteadiness is a common complaint at vestibular clinics. Bilateral vestibulopathy (BVP) is a major cause of chronic unsteadiness but is often overlooked. Although diagnostic criteria for BVP have been established by the Barany Society, isolated vertical canal hypofunction can remain undiagnosed. Recently, the video head-impulse test has enabled clinicians to assess vertical semicircular canal function at clinics. This study aimed to compare the features of isolated bilateral posterior semicircular canal hypofunction (IBPH) with those of BVP diagnosed based on the Barany criteria. The clinical data of 8 IBPH patients that had been diagnosed using our diagnostic criteria (sex, age, subjective symptoms, questionnaire, video head-impulse test and stabilometry) were analyzed and compared with those of 6 BVP patients diagnosed using the Barany criteria. The IBPH patients were all aged >70 years, while the age range of the BVP patients was wider. While the BVP patients complained of both oscillopsia during body movement and unsteadiness in darkness, the IBPH patients complained of unsteadiness in darkness without oscillopsia during body movement. The IBPH patients exhibited milder clinical findings than the BVP patients. IBPH can cause mild unsteadiness in the elderly. Clinicians should be aware that IBPH can cause unsteadiness in the elderly. [ABSTRACT FROM AUTHOR]

An operating 2‐MW wind turbine has been scanned and analysed using 2D computational fluid dynamics (CFD) and blade element momentum (BEM) analysis. The current work illustrates using full‐scale 3D CFD simulations the differences between 2D and 3D simulations and its impact on the local aerofoil vortex shedding frequency. The outcome shows that despite a pressure redistribution and lift change introduced by the blade span and rotation, the vortex shedding frequency remains similar between 2D and 3D thereby validating the novel fatigue calculation method previously proposed. [ABSTRACT FROM AUTHOR]

In 2007, the Bárány Society embarked on a project to establish definitions of vestibular syndromes and disorders based on best available evidence, referred to as the International Classification of Vestibular Disorders (ICVD). Since then, numerous publications providing consensus-driven diagnostic criteria for vestibular symptoms, syndromes, and disorders have been published. Here, we reflect on the rationale for developing the ICVD as well as its subsequent achievements, challenges, and outlook. In this summary of the work of the ICVD to date, the authors will focus on practical aspects to help improve the utility and applicability of these diagnostic criteria moving forward. [ABSTRACT FROM AUTHOR]

The flow dynamics inside cavities associated with turbulent incoming flow and oscillations of the cavity shear layer is an important field of study that has attracted many researchers aiming to understand the complex flow features using both numerical and experimental techniques. Such a flow exists in many industries, such as in the automobile industry for flows over the sunroof of vehicles, and in the energy industry such as in finned heat-exchangers, combustion chambers, and turbines that utilizes wind energy harvesting in buildings. Most of those studies focused on the aero-acoustic mechanism and its control. Despite its wide industrial applications, heat transfer in cavity with oscillating shear layer remains less studied in the literature. The present paper presents a literature review of various studies that focuses on the heat transfer mechanism in those cavity configurations and how it is affected by the flow parameters.

This paper presents high‐resolution field measurements of the wind and saltation fields using miniphones and anemometers located 20–40 mm apart (bed‐parallel) and 10–40 mm above the bed. The average wind speeds at the Shoalhaven Heads, Australia and the Jericoacoara, Brazil field sites are both 4.4 m s−1, and the average saltation rates are 5.0 and 22.2 counts/mm2 s−1, respectively. Normalized cross‐covariance analysis between the wind and saltation time series indicates a dominant saltation response time of 0 s. Cross‐wavelet analysis focusing on short‐duration events characterizes statistically significant wind–sand events and intervals. In the high aeolian saltation rate environment (Brazil), the events and intervals averaged 1.9 and 12.2 s. The low transport environment (Australia) resulted in 2.1 s events and 10.8 s intervals. This study demonstrates that wind–sand events occur about 15% of the time but account for about 23% of the sand transport. These results were possible because of the presentation of a wavelet‐derived event time series. The criticality of tightly controlled field experiments to measure coincident wind and saltation fluctuations with co‐located sensors was demonstrated. This paper emphasizes the importance of the contribution of saltation events to time‐averaged transport rates, which influences sediment flux modelling. [ABSTRACT FROM AUTHOR]

Objectives: Stance and gait unsteadiness along with vertigo contribute to a central vestibular disorder. For objective analysis ultrasound-computer-craniocorpography (US-COMP-CCG) can be used. Aim of the study was to characterize the unsteadiness in central vestibular disorders and discuss the possible diagnostic usage of US-COMP-CCG. Methods and results: Hundred-and-ninety patients (70 male and 120 female, mean age ± SD, 58.94 ± 15.27) suffering from central vestibular disorder and 230 healthy control patients (78 male and 152 female, mean age ± SD, 50.94 ± 15.27) were enrolled. Stance and gait analysis was according to vestibulospinal tests of US-COMPCCG. IBM SPSS V24 software was used for statistical analysis. Mann-WhitneyU test and Chi-square test were used, along with sensitivity and specificity categorization. The significance level was p

A numerical study is conducted to determine the hydrodynamic coupling characteristics of a contra-rotating azimuth propulsor (CRAP) in open-water conditions. The detached-eddy simulation (DES) method is utilized to run simulations. A grid verification is conducted and the numerical results are validated based on a puller-type podded propeller. The hydrodynamic forces (i.e., thrusts and torques) are in accordance with the experimental data. The validated numerical method is utilized for subsequent CRAP simulations. The hydrodynamic performance and hydrodynamic coupling characteristics of CRAP are quantitatively analyzed according to forward propeller (FP), rear propeller (RP), and pod unit (PU) indicators with special focus on the hydrodynamic forces and the corresponding unsteadiness. PU appears to have essentially the same effect on the hydrodynamic performance of FP and RP. RP has a weak effect on the hydrodynamic performance of FP, while FP intensely affects that of RP. In general, the CRAP unsteadiness is dominated by RP, especially under heavy loading conditions.

Notwithstanding current understanding of vertigo, there are various clinical scenarios which are intriguing for clinicians, where patients have been too symptomatic but the presentation does not fit into any diagnosis. We stumbled upon a new entity during literature search known as Persistent Postural Perceptual Dizziness (PPPD). It fills the lacuna where we are often left wanting for diagnosis in the existing pool of knowledge. This case series has been prepared keeping in view the lack of data regarding PPPD in Indian population. For better understanding we present the illustration of our patients in this case series. We presented the details of three patients who were diagnosed as PPPD and managed effectively and followed up for one year. The nomenclature portrays the core concept of dizziness. The diagnostic criteria clearly define PPPD. It should not be used as escape or exclusion diagnosis. Our case series highlights various presentation of, not so uncommon, PPPD in Indian population. The case series has been brought out to address the deficiency of knowledge in dealing with intriguing vertigo. Careful thorough history is important to reach a diagnosis and avoids unwarranted vestibular sedatives. It highlights that proper counselling and vestibular rehabilitation can help the patients overcome their chronic disability. [ABSTRACT FROM AUTHOR]

• Unsteady aerodynamic stage-interaction in two-stage radial turbines at pulsation is firstly studied. • HPT performance is firstly confirmed to be significant different from that of quasi-steady case. • Precessions of volute swirling flow, rotor incidence loss and tip leakage loss dominates HPT loss discrepancy when the valve is open. • Direction of upstream swirling flow from HPT exerts important impacts on LPT performance. Regulated multi-stage turbocharging is an indispensable technology to achieve high boosting pressure and hence power recovery for High-Altitude Long-Endurance Unmanned Aerial Vehicle (HALE UAV). Inevitably, unsteady interstage coupling has become a key factor restricting the pursuit of higher aerodynamic performance in multi-stage turbochargers. This study is to investigate the unsteady gasdynamic behavior of two-stage radial turbines and aimed to obtained the knowledge of unsteady aerodynamic interaction at pulsating conditions. Results reveal an obvious difference in the performance discrepancy mechanisms of high-pressure turbine (HPT) and low-pressure turbine (LPT). HPT shows more unsteady than that of LPT according to the discussion on mass accumulation and local temporal gradient. Furthermore, this unsteadiness is drastically enhanced when the valve is open. For HPT with open valve, a sharp reduction of up to 10.7% in the cycle-averaged efficiency is observed. Both the volute and the rotor are the main components causing the deterioration of efficiency. Swirling flow precession leads to a dramatically loss generation in the volute. Leading-edge separation and tip leakage flow are the dominated factors in rotor. The former is primarily attributed to inlet swirling flow and the latter is predominantly attributed to the pulsating effect. For LPT, the performance is not sensitive to the valve state, with no more than 3% discrepancy on efficiency. At specific velocity ratio, the negative swirling flow tends to exert a positive effect to the rotor efficiency, whereas the positive swirling flow leads to a higher entropy generation in rotor passage. [ABSTRACT FROM AUTHOR]

Objectives. The aim was to analyze and compare the compensatory process, vestibular dysfunction, postural control, and perceived disability in a population of patients with vestibular neuritis (VN). Material and Methods. This is a prospective and longitudinal study of 67 patients diagnosed with VN. Inclusion criteria were sudden onset of vertigo, unidirectional spontaneous horizontal nystagmus, and impairment in vestibular test. Exclusion criteria were imaging or clinical findings of any neurotologic disorder. All vestibular tests were performed; vHIT, vestibular evoked myogenic potentials (VEMPs), caloric test and computerized dynamic posturography (CDP), dizziness handicap inventory (DHI), and visual analogue scale (VAS) were also performed at every follow up. Results. We observed a correlation between the composite score of CDP and baseline vestibular function elicited either by caloric test, VEMPs, or vHIT. There was a significant correlation between baseline vestibular function and first visit questionnaire scores. The main gain recovery for the horizontal canal was 0.1 ± 0.04 for the first three months. After that, the gain recovery significantly decreased. The presence of covert and overt saccades', latency and amplitude decreased, respectively, after the 6-month period, when compared to the baseline results. We also observed a decrease in the PR score from 3 months after the vestibular insult until the last follow up. We observed a significant decrease in DHI and VAS from the first visit until the last one. Those patients with an initial HC gain below 0.5 had significantly higher DHI and VAS scores at every follow up. Conclusions. There are different measurements that could become a complete measurement of the state of compensation, postural control, and disability of the patients. There is a time window in which the vestibular restoration could give us clinical insights regarding the management of VN patients. [ABSTRACT FROM AUTHOR]

In the article, the authors discuss their study to determine the proper timing for nystagmus evaluation by emergency physicians (EP) using the HINTS and STANDING algorithms. Other topics include the possible causes of dizziness or vertigo like benign inner ear disease, and how dizziness was considered as the most common symptom linked to missed stroke diagnosis.

Prediction of differential molecular diffusion remains a great challenge for flamelet modeling of turbulent non-premixed combustion. This work addresses this challenge through a priori and a posteriori testing of flamelet models by using DNS databases to enable a detailed examination of the model capability and limitation for the prediction of differential molecular diffusion under different combustion conditions characterized by different Reynolds numbers and Damköhler numbers. The emphasis is on the effect of unsteadiness and scalar dissipation models on the flamelet modeling. Two sets of Sandia DNS of temporally evolving turbulent non-premixed jet flames are used for the study, including six different cases. Three of the DNS cases are based on the CO/ H 2 fuel with different Reynolds numbers, and the other three cases are based on the C 2 H 4 fuel with different Damköhler numbers. The unsteady effect is examined by considering both steady and unsteady flamelet models in the context of Reynolds averaged Navier–Stokes simulations for the model examination. Different differential molecular diffusion models are incorporated in the flamelet models such as the linear differential diffusion model and the non-linear differential diffusion model (Wang, Phys Fluids 28:035102, 2019). It is found that the use of unsteady flamelet models can generally improve the model prediction for differential molecular diffusion when compared with the steady flamelet models. This suggests the importance of considering the unsteady effect in flamelet modeling of differential molecular diffusion. In the unsteady flamelet modeling, different models for the representative scalar dissipation rate are examined and compared. It is found that, in order to adequately capture differential molecular diffusion, an appropriate model for the scalar dissipation rate is needed in addition to the consideration of unsteadiness. [ABSTRACT FROM AUTHOR]

The article considers the physical model of the deformation interaction of the tool with the surface being treated in the process of surface-plastic deformation by diamond smoothing. A step-by-step diagram of the formation relief of the surface of the part during diamond smoothing with elastic and rigid fastening of the tool is presented. Given the general stationarity of the smoothing process under steady-state conditions, two unsteady periods are distinguished, characterized by instability of the surface formation conditions. The reasons and conditions for the unevenness of the process are illustrated by the surface deformation schemes for elastic and rigid fastening of the diamond tip. The sequence of stages of the formation of the surface layer in the initial period of the unsteady process is shown, when the tool comes into contact with the processed surface, and in the final unsteady period, when the tool leaves the contact interaction with the workpiece. At the same time, features are noted in the deformation pattern of the transitional periods of treatment with an elastic and rigid tool. The instability of the parameters of the contact interaction of the tool and the part in the unsteady periods of diamond smoothing causes the probability of the formation of defective areas on the treated surface. Expressions are given for determining the relief parameters of transitional sections of a smoothed surface and an estimate is given for the length of the transitional zone at the tool input in contact with the part and at the output from the contact, depending on the hardness of the processed material. The probable length of the transition sections, characterized by a deviation of the diametrical dimensions and surface shape, should be taken into account when designing the functional elements of the part and the technological process of finishing and hardening smoothing.

The article discusses the implications of rethinking force steadiness, particularly focusing on the metric of yank magnitude as a more accurate indicator of force unsteadiness compared to coefficient variation of force (CVF). It addresses the need for normalization of yank magnitude and compares the effectiveness of yank and CVF in predicting movement instability, advocating for further research in this area.

Motivated by magnetic polymer manufacturing applications, the present research article examines theoretically the hydromagnetic boundary layer flow of an electrically conducting non‐Newtonian couple stress fluid due to a transient shrinking (contracting) porous sheet. The conservation partial differential equations for mass and momentum are rendered into a fifth‐order nonlinear ordinary differential equation via similarity transformations with associated boundary conditions. A semi‐analytical/numerical scheme employing Lagrangian multipliers and known as the variational iteration method (VIM) is implemented to solve the ordinary differential boundary value problem. Validation of the solutions is conducted by benchmarking against earlier Newtonian studies and very good agreement is achieved. A detailed assessment of the impact of couple stress (rheological), unsteadiness, magnetic body force parameter, and wall transpiration (suction/injection) parameter on flow characteristics is conducted with the aid of graphs. A significant deceleration in the flow is computed with increasing injection (acceleration is caused with greater suction) and acceleration is induced with higher unsteadiness parameter values. Increasing magnetic field (higher magnetic number) generates flow acceleration, rather than the customary deceleration, due to the shrinking sheet dynamics. A stronger couple stress effect manifests in strong retardation in the boundary layer flow and an increase in momentum (hydrodynamic|) boundary layer thickness. VIM demonstrates excellent convergence and accuracy and shows significant promise in studying further magnetic polymer fabrication flow problems. [ABSTRACT FROM AUTHOR]

Background: Primary orthostatic tremor (POT) is a rare disorder for which current treatments are largely ineffective. Following up on our recent report of complete resolution of POT symptoms in a patient using low doses of perampanel, we describe our experience of perampanel in 20 patients. Methods: Twenty patients whose neurologists prescribed perampanel were recruited. Initial dose was 2 mg/day, which was increased to 4 mg/day after the first month. Treatment efficacy was self-scored from +3 to −3 at 1 and 3 months. Results: Eight patients withdrew due to adverse effects. Of the 12 patients who completed the study, 92% indicated that their POT symptoms had improved after 1 month, with 75% indicating moderate to marked improvement (mean score 1.9 ± 0.9). This improvement was not sustained by follow-up at 3 months (mean score 0.9 ± 1.3). A rebound of POT symptoms that lasted 2–6 weeks was observed in most patients who withdrew. Discussion: Our experience with this series of cases points to the potential of low-dose perampanel as a treatment for POT, although poor tolerance and the possibility of a non-persistent therapeutic benefit need to be considered. Controlled studies are needed to confirm these findings.

Background: Orthostatic tremor (OT) is a rare symmetric tremor disorder occasionally observed in association with other movement disorders. Case report: We report the presence of a fast OT in a case of Parkinson’s disease (PD), and provide a comprehensive review of the literature. Discussion: A fast OT presenting as unsteadiness may be a presenting symptom of PD. This symptom may be nonresponsive to levodopa, and benzodiazepines should be prescribed to adequately control the OT and reduce disability.

Evaporation of a single n-decane droplet at high pressures and high temperature has been studied experimentally under normal and microgravity conditions. Ambient pressure was set at 0.10 and 0.50 MPa. Ambient temperature was fixed at 773 K. At normal gravity, initial droplet diameter was varied from 0.4 to 0.80 mm. To examine unsteadiness of droplet evaporation, instantaneous droplet evaporation rate coefficient was measured. The effect of natural convection on instantaneous droplet evaporation rate coefficient was evaluated as a function of the Grashof number. The unsteadiness of droplet evaporation appears in entire period of evaporation lifetime. The effect of natural convection on instantaneous droplet evaporation rate coefficient changes during evaporation and its dependence on Grashof number in the range where the effect of natural convection was regarded as quasi-steady was expressed as the empirical equations. [ABSTRACT FROM AUTHOR]

Centrifugal compressor is exposed to pulsating backpressure due to the movement of intake valves in internal combustion engine. The performance of compressor deviates from the steady performance map, which affects the matching between turbocharger and engine. The behavior of compressor system at pulsation conditions are investigated via an in-house developed 1D unsteady code validated by experimental results. The influence of pulse frequency, magnitude and compressor characteristic curve on the compressor transient responses, including filling-emptying effect and wave dynamics, are analyzed. Results show that the strength of wave dynamics grows stronger with the increasing of pulse frequency, while the strength of filling-emptying effect increases first then decreases. The rise of pulse magnitude results in an almost linearly increasing of filling-emptying effect, while it can hardly affect the wave dynamics. Furthermore, the influence of pulsation magnitude and frequency represents the influence of local pressure gradient, and a correlation as quadratic curve can be evaluated between the pressure gradient and compressor unsteadiness. On the other hand, the influence of operating point, including the average mass flow rate and the slope of characteristic curve, is confirmed to be evidently smaller, comparing to the influence of pulsation frequency and magnitude. This study is helpful to estimate the behavior of compressor and the discrepancy of performance when operating at unsteady environment or matched with engine. [ABSTRACT FROM AUTHOR]

Objective: To evaluate mortality among patients referred for suspected vestibular disorder and to examine whether specific symptoms or disorders predict long‐term survival among patients with dizziness or vertigo. Study Design: Retrospective cohort study. Methods: This retrospective cohort study analyzed long‐term survival data. Consecutive patients examined for suspected vestibular disease at an otolaryngology clinic completed a detailed questionnaire regarding symptoms and comorbidities. Results: The study included 1,931 patients. Their mean age (standard deviation) was 50.5 (16.5) years, and 60% were women. The mean follow‐up period was 20.6 years (range, 15.3–27.5 years). The standardized mortality ratio for the entire cohort compared with the Norwegian age‐ and sex‐matched population was 1.03 (95% confidence interval [CI]: 0.94–1.12), illustrating no difference in overall survival. Patients with a cerebrovascular cause of dizziness had higher mortality in adjusted Cox regression analyses (hazard ratio [HR] 1.56, 95% CI: 1.11–2.19), whereas patients reporting periodic or short attacks of dizziness had lower mortality (HR 0.62 [0.50–0.77] and 0.76 [0.63–0.93], respectively). Reported unsteadiness between dizziness attacks was associated with higher mortality with an HR of 1.30 (95% CI: 1.08–1.57). Conclusion: This long‐term study found comparable mortality rates between patients evaluated for suspected vestibular disorder and that of the general population. However, subgroup analyses showed reduced mortality in patients with periodic or short attacks of dizziness and increased mortality in patients with unsteadiness between attacks or cerebrovascular causes of dizziness. The time course of vestibular symptoms should be determined, and thorough evaluation including fall risk and comorbidities must be considered in patients with nonepisodic symptoms. Level of Evidence: 3 Laryngoscope, 131:E2031–E2037, 2021 [ABSTRACT FROM AUTHOR]

Rainer Spiegel,1 Roger Kalla,2 Georgios Mantokoudis,3 Raphael Maire,4 Heiko Mueller,5 Robert Hoerr,5 Ralf Ihl6 1Division of Internal Medicine, Basel University Hospital, University of Basel, Basel, Switzerland; 2Department of Neurology, Inselspital, Bern University Hospital, Bern, Switzerland; 3Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital, Bern University Hospital, Bern, Switzerland; 4Lausanne University Hospital, Lausanne, Switzerland; 5Clinical Research Department, Dr Willmar Schwabe GmbH & Co. KG, Karlsruhe, Germany; 6Department of Psychiatry, University of Duesseldorf, Alexian Research Center Krefeld, Krefeld, Germany Background: Tinnitus and dizziness are frequent in old age and often seen as concomitant symptoms in patients with dementia. In earlier clinical trials, Ginkgo biloba extract EGb 761® was found to alleviate tinnitus and dizziness in elderly patients. Consequently, a meta-analysis was conducted to evaluate the effects of EGb 761® at a daily dose of 240 mg on tinnitus and dizziness associated with dementia. Methods: Randomized, placebo-controlled clinical trials of G. biloba extract EGb 761® identified by a systematic database search were included in a meta-analysis if they met all of the following selection criteria: 1) diagnosis of dementia according to generally accepted criteria, 2) treatment period of at least 20 weeks, 3) outcome measures covering at least two of the three conventional domains of assessment, 4) presence and severity of dizziness and tinnitus were assessed, and 5) assessment was done before and after randomized treatment. Results: Five trials that met the inclusion criteria were included in the meta-analysis. The risk of bias was judged as low, with Jadad scores of 3 and 5. In all trials, 11-point box scales were used to assess the severity of tinnitus and dizziness. Overall, EGb 761® was superior to placebo, with weighted mean differences for change from baseline, calculated in meta-analyses using random effects models, of -1.06 (95% CI: -1.77, -0.36) for tinnitus (p = 0.003) and -0.77 (95% CI: -1.44, -0.09) for dizziness (p = 0.03). Conclusion: Our findings support the notion that EGb 761® is also effective in alleviating concomitant neurosensory symptoms in patients with dementia. Keywords: neurodegenerative disorders, gait, unsteadiness, inner ear, hearing, review

This work investigates the start-up characteristics of linear compressors in a refrigeration system through experiment and simulation. Experiments are carried out by a refrigeration test system with a linear compressor controlled by a LabVIEW platform. A simulation model that considers the nonlinear process of gas force is set up on the basis of Runge-Kutta method for linear compressors. Compared with the experimental results, the simulation errors are within 15%, including the unstable state. The influences of ambient temperature and power frequency on linear compressors are studied through experiments. Unstable phenomena exist at 25°C ambient temperature compared with the designed ambient temperature of 35°C. The unsteadiness mechanism is analyzed by simulation. Simulation analysis indicated that two sensitive stages of linear compressors, namely, starting to pump and touching top dead center, are unstable. Furthermore, properly increasing equivalent mass (approximately 3%) or spring stiffness during the design stage can be a practical method to improve the stability of linear compressors. [ABSTRACT FROM AUTHOR]

The numerical solution of the problem of compressible gas flow past a plate with upstream-moving surface is obtained. Unstable time-periodic and stable steady-state solutions of this problem are discussed. A new type of unsteady periodic flow in which the varying characteristics turn out to be integrally asymmetric at transonic velocities is obtained. [ABSTRACT FROM AUTHOR]

The applicability of two-parameter turbulence models to investigation of the impact of free-stream high-intensity turbulence on the characteristics of near-wall flow and heat- and mass-transfer in the steady-state and unsteady boundary layers under the conditions of blowing and suction through permeable surface sections is analyzed. The calculated results obtained in specifying a constant relative mass flow rate parameter in the cases of blowing and suction through permeable sections are compared with the experimental data. The mechanisms of the interaction of blowing and suction of a gas of homogeneous constitution with the flow on two permeable sections upstream and downstream of these sections in the near-wall zone of turbulent boundary layer are studied on the basis of numerical solutions. The calculated results obtained in specifying a time-dependent flow-rate parameter on two permeable surface sections are given. [ABSTRACT FROM AUTHOR]

An unsteady five-hole probe has been developed for the measurement of turbulent flow in tidal channels. Such measurements are vital for accurate prediction of unsteady loads on tidal turbines. Existing field-based velocimeters are either unable to capture the required range of frequencies or are too expensive to profile the variation of turbulence across a typical tidal power site, and thus the available data is inadequate for turbine design. This work adapts the traditional five-hole wind tunnel probe to achieve a low-cost device with sufficient frequency range for tidal turbine applications. The main issue in the marine environment is that the ambient hydrostatic pressure is much higher than the dynamic pressure. This has been overcome by using novel calibration coefficients and differential transducers. In flume tank tests against laser Doppler velocimeter measurements, the frequency response of the probe has been shown to be sufficient to capture all the frequencies necessary for tidal turbine design. [ABSTRACT FROM AUTHOR]

The flow around a space launcher is dominated by flow separation at the junction between the main body and engine and strongly influenced by the propulsive jet. The flow field is highly unsteady with strong local pressure and temperature loads. To conceive a means of mitigating these effects and allow for smarter launcher designs, a better understanding is necessary. The wake of a generic axisymmetric launcher model with and without afterexpanding propulsive jet was investigated at Mach 2.9, a Reynolds number Re D = 1.3 · 10 6 (model diameter D), and a nozzle exit velocity of the jet simulation of Mach 2.5. I observed the evolution of the flow and its spectral content with velocity measurements with particle image velocimetry and wall-pressure recordings. Coherent structures were analyzed based on a proper orthogonal decomposition. The propulsive jet has two major influences. First, the turbulent intensities in the shear layer are damped, and the larger structures in the wake contain less turbulent kinetic energy than in the baseline case without propulsive jet. Second, the reattachment process is modified and the wake instability phenomena change accordingly. Without propulsive jet, large-scale separation with reattachment on the nozzle fairing occurs and the low-frequency unsteadiness of the closed separation bubble/recompression-shock system is relevant. This phenomenon only has a minor influence under the influence of the jet plume, where the flow is displaced away from the surface and the reattachment process is incomplete. Here, shear-layer instabilities become more prominent. [ABSTRACT FROM AUTHOR]

Background: Dizziness is common among older people and falling is a feared complication. Aim: The purpose of this study was to investigate the presence of dizziness and its association with falls, walking speed and fear of falling, including sex differences, among 79-year-olds. Secondary purposes were to describe the relationship between dizziness and falls to number of medications and diseases. Method: The study consisted of the fifth cohort of Gothenburg's H70 birth cohort studies. A sample of 662 79-year-olds (404 women, 258 men) were investigated with questions regarding dizziness, previous falls and falls efficacy [estimated according to the falls efficacy scale Swedish version (FES (S))]. Functional tests included self-selected and maximal walking speed over 20 m. Results: Dizziness was reported among 51% of the women and by 58% of the men (p = 0.12). Approximately, 40% had fallen during the past 12 months (41% women, 38% of the men, p = 0.48). Dizziness was related to a higher risk of falls among women (OR 2.63 (95% CI 1.67−4.14, p < 0.0001), but not among men (OR 1.07, 95% CI 0.63−1.82, p = 0.8). Dizzy individuals had lower scores on FES (S) (p < 0.01), more medications (p < 0.001) and diseases (p < 0.001) than those without dizziness. Participants who reported dizziness walked 10% slower than participants without dizziness (p < 0.001). Conclusion: Women with dizziness more often reported falls compared to women without dizziness—a trend that was not seen among men. Persons with dizziness walked slower. Many medications increased risk of falling; hence, number of medications alone might help pinpoint risk groups for falling. [ABSTRACT FROM AUTHOR]

A three-dimensional, multi-passage unsteady numerical study was conducted to enhance the understanding of unsteady flow phenomena in the tip region of highly loaded compressors. The first-stage rotor of a three-stage transonic low-reaction compressor was chosen as the computational model. Three different tip clearance sizes were calculated to demonstrate the effect of the tip clearance dimension on the unsteadiness in the rotor tip region. It was found that the unsteadiness existed at the vicinity of the stall point when the tip clearance size was larger than the design value. The unsteadiness in the tip region appeared as a "multi-passage structure" in the nine-passage unsteady simulation and it propagated along the circumferential direction. Tip leakage vortex breakdown was the source of unsteady flow behavior. Besides, special attention was paid to the difference between the conventional transonic rotor and the low-reaction rotor. The scale of the flow separation downstream of the shock wave was controllable for the low-reaction rotor even at near-stall conditions. The boundary layer would reattach to the blade surface due to local axial acceleration. Finally, attempts were made to study the stall mechanism of the low-reaction rotor. [ABSTRACT FROM AUTHOR]

Long-distance gas transfer requires high pressure, which has to be reduced before the gas is conveyed to the customers. This pressure reduction takes place at natural gas pressure reduction stations, where gas pressure is decreased by using gas flow energy for overcoming local resistance, represented by a throttling valve. This pressure energy can be reused, but it is difficult to implement it at small pressure reduction stations, as the values of unsteadiness significantly increase when the gas approaches consumers, whereas gas flow rate and pressure decrease. This work suggests replacing throttling valves at small pressure reduction stations for expander-generator units, based on volumetric expanders. Two implementations are proposed. A mathematical model of gas-dynamic processes, which take place in expander-generator units, was developed using math equations. With its help, a comparison was made of the stability of the operation of two possible control schemes in non-stationary conditions, and the feasibility of using an expander-generator regulator as a primary one for a small natural gas pressure reduction station was confirmed.