Positive diagnostic positional tests in BPPV are higher in the morning than in the afternoon: a retrospective study

ObjectivePositional tests are the standard for diagnosing benign paroxysmal positional vertigo (BPPV). We evaluated the relationship between the timing of the testing during the day and the rate of pathological findings.MethodsA retrospective analysis of clinical records from 929 patients with a medical history consistent with the diagnosis of BPPV from Jan 1st, 2023 until Dec 31st, 2024 was performed. The aim was to assess timing of examinations and diagnostic findings. Morning examinations were categorized as those initiated from 8 a.m. to 12 p.m., while afternoon examinations were defined from 2 p.m. to 5 p.m. The rate of pathological positional tests was evaluated based on the observation of positional nystagmus induced by the diagnostic maneuvers.ResultsA total of 929 individuals with the presumed diagnosis of BPPV were examined by diagnostic positional maneuvers. Five hundred and ninety individuals (63.51%) were examined in the morning and 339 (36.49%) in the afternoon. The positive rate of BPPV testing was 72.54% (428/590) in the morning group and 64.01% (217/339) in the afternoon group (P < 0.01). Subgroup-analysis by semicircular canal type showed the number of posterior semicircular canal BPPV (pcBPPV) was 308 of 590 (52.20%) in the morning and 154 of 339 (45.43%) in the afternoon, with a significant difference (p = 0.010). For horizontal semicircular canal BPPV (hcBPPV), the number was 115 of 590 (19.49%) in the morning and 60 of 339 (17.70%) in the afternoon (p = 0.080). Hourly analysis for both canal types revealed the highest positive rate (74.6%) between 8:00 a.m. and 8:59 a.m. and lowest (51.9%) between 2:00 p.m. and 2:59 p.m., with higher positive rates in the morning (p = 0.005). Multi-variate analysis showed a strong association with examination timing (p = 0.005) with no correlation between age/gender and positive testing.ConclusionThe overall positive rate for positional tests for BPPV was significantly higher in the morning than in the afternoon. Subgroup analysis showed a statistically difference for pcBPPV but not for hcBPPV. These findings hold clinical implications for optimizing examination scheduling and improving diagnostic and treatment strategies for patients with vertigo. Prospective studies are warranted to validate the reliability and validity of these observations

Ecological Response to the Diluted Water in Guangxi during the Spring Monsoon Transition in 2021

Based on the field survey data of the Guangxi offshore voyage in May 2021, the distribution characteristics of the wind field during the spring monsoon transition period, the temporal and spatial changes in the diluted water path, and the corresponding ecological responses were analyzed. The results show the following: the core region of diluted water is located along the coast of Guangxi, and the diluted water expands to the east and west at the same time, where the thickness of the diluted water reaches 20 m. Under the combined action of the easterly wind and westward current, the westward expansion trend was stronger than the eastward expansion trend. The surface distribution of suspended solids, chlorophyll a, dissolved oxygen, and active silicon is similar to the dispersion range of the diluted water, and the high-value areas all appear near the estuary, which is basically consistent with the salinity distribution in the core region of the diluted water. Under the mixing caused by the wind and tide in the estuary area, the difference in dissolved oxygen between the surface and bottom layer is small, while in the nearshore area, the stratification of seawater hinders the dissolved oxygen’s downward transmission, resulting in a large difference in dissolved oxygen between the bottom and the surface

Research on the Characteristics of Surface Flux and Surface Parameters of Meadow Underlying Surface in the Source Region of Yellow River

Based on observation data from January 1st to December 31st in 2014 at Maduo Site, which is located near the Yellow River source area in the Qinghai-Tibet Plateau, this research examined how the surface flow of alpine meadow underlying surface varies. The applicability of the land-surface process models CLM5.0 and CLM4.5 in alpine grassland was also tested. The findings revealed that total radiation in the Yellow River source area was lower in the winter but quickly increased after mid-March, peaked in June or July, and then gradually decreased. The surface reflected radiation was affected by both the total radiation and surface albedo. Its seasonal variation showed different characteristics than the total radiation. Due to the snow on the surface, the short-wave radiation reflected by the surface was larger in winter, while the surface reflected radiation in summer was relatively small, especially after the rainy season. Long-wave surface radiation followed the same seasonal pattern as air counter radiation, with a low point in winter and a high point in summer. Due to cloud cover and other variables, however, long-wave surface radiation was larger than atmospheric counter radiation. The sensible heat flux and net radiation varied similarly until July (rainy season), but after July, the latent heat flux and net radiation followed the same pattern until the soil was frozen in early November. For the whole year, the study of regional surface flux was mainly focused on latent heat flux. Corresponding to sensible heat and latent heat, the daily average of soil heat flux was above 0 from mid-March to late August, which meant that the soil heat flux was transmitted from the surface soil to the deep layer, while the rest of the time showed a negative, with soil heat flux transmitted from the deep layer to the surface soil. In late March, the daily average heat flux of soil was abnormally large, which was related to the melting of frozen soil. Generally, for the whole year, soil heat flux was transmitted from the deep layer to the surface soil. The simulation results of CLM5.0 and CLM4.5 for radiation flux and surface heat flux are very close to the observed values, especially CLM5.0. This indicates that the simulation effect of the model in Alpine Grassland in the source region of the Yellow River has been significantly improved after improving many parameterization schemes and dynamic processes in CLM5.0. However, the soil freezing and thawing process and snow parameterization scheme in CLM need to be further improved. Generally, the daily average CO2 flux during the frozen period of soil was 0. In May, September, and October, the respiration of alpine meadows dominated, surface releasing CO2, while in early and middle June, photosynthesis played the leading role, surface absorbing CO2. During the period from late June to mid-August, when both the moisture and temperature of soil were higher, and the surface vegetation experienced rapid growth, the daily average CO2 flux increased sharply. On the contrary, when the frozen soil melted, the CO2 flux released by the surface increased significantly.</jats:p

Research on Dynamic Modeling Method and Flying Gait Characteristics of Quadruped Robots with Flexible Spines

In recent years, both domestic and international research on quadruped robots has advanced towards high dynamics and agility, with a focus on high-speed locomotion as a representative motion in high-dynamic activities. Quadruped animals like cheetahs exhibit high-speed running capabilities, attributed to the indispensable role played by their flexible spines during the flight phase motion. This paper establishes dynamic models of flexible spinal quadruped robots with different degrees of simplification, providing a parameterized description of the flight phase motion for both rigid-trunk and flexible-spine quadruped robots. By setting different initial values for the spine joint and calculating the flight phase results for both types of robots at various initial velocities, the study compares and analyzes the impact of a flexible spine on the flight phase motion of quadruped robots. Through comparative experiments, the research aims to validate the influence of a flexible spine during the flight phase motion, providing insights into how spine flexibility affects the flight phase motion of quadruped robots

Ecological Response to the Diluted Water in Guangxi during the Spring Monsoon Transition in 2021

Based on the field survey data of the Guangxi offshore voyage in May 2021, the distribution characteristics of the wind field during the spring monsoon transition period, the temporal and spatial changes in the diluted water path, and the corresponding ecological responses were analyzed. The results show the following: the core region of diluted water is located along the coast of Guangxi, and the diluted water expands to the east and west at the same time, where the thickness of the diluted water reaches 20 m. Under the combined action of the easterly wind and westward current, the westward expansion trend was stronger than the eastward expansion trend. The surface distribution of suspended solids, chlorophyll a, dissolved oxygen, and active silicon is similar to the dispersion range of the diluted water, and the high-value areas all appear near the estuary, which is basically consistent with the salinity distribution in the core region of the diluted water. Under the mixing caused by the wind and tide in the estuary area, the difference in dissolved oxygen between the surface and bottom layer is small, while in the nearshore area, the stratification of seawater hinders the dissolved oxygen’s downward transmission, resulting in a large difference in dissolved oxygen between the bottom and the surface.</jats:p

Observer-based hierarchical distributed model predictive control for multi-linear motor traction systems

This paper proposes an observer-based hierarchical distributed model predictive control (MPC) strategy for ensuring speed consistency in multi-linear motor traction systems. First, a communication topology is considered to ensure information exchange. Secondly, the control architecture of each agent is divided into upper layers and lower layers. The upper layer utilizes a distributed MPC method to track the leader's speed. The lower layer uses a decentralized MPC method to track the command signals sent by its upper layer controller. In addition, to eliminate the negative impact of disturbance, a nonlinear disturbance observer is designed. We then prove the asymptotic stability of the entire system by properly designing the Lyapunov equation. Finally, the feasibility of the proposed strategy is verified based on several simulations

Fractional Order Terminal Sliding Mode Observer for State of Charge Estimation of Lithium-Ion Battery

Lithium-ion battery is widely used for its high energy density, long cycle life, non-pollution and other advantages. They are expected to be mainstream power source for future applications on electrochemical energy storage. However, it has been a long-standing problem to obtain an accurate real-time state estimation for lithium-ion battery with high nonlinearity and inevitable inconsistency. In this paper, the design of a new estimation method for state of charge (SOC) of lithium-ion battery is introduced. Based on the equivalent Thevenin model, a fractional order sliding mode observer is proposed to estimate terminal voltage, SOC and polarization voltage and the stability proof is given. Compared to the frequently-used Kalman filter method and the current integration method, this method shows higher accuracy and robustness. As a result, the feasibility of the proposed method is verified

Finite-Time Stability Analysis for a Class of Continuous Switched Descriptor Systems

Finite-time stability has more practical application values than the classical Lyapunov asymptotic stability over a fixed finite-time interval. The problems of finite-time stability and finite-time boundedness for a class of continuous switched descriptor systems are considered in this paper. Based on the average dwell time approach and the multiple Lyapunov functions technique, the concepts of finite-time stability and boundedness are extended to continuous switched descriptor systems. In addition, sufficient conditions for the existence of state feedback controllers in terms of linear matrix inequalities (LMIs) are obtained with arbitrary switching rules, which guarantee that the switched descriptor system is finite-time stable and finite-time bounded, respectively. Finally, two numerical examples are presented to illustrate the reasonableness and effectiveness of the proposed results

Distributed Model Predictive Consensus Control of Unmanned Surface Vehicles with Post-Verification

In this paper, the consensus control of unmanned surface vehicles (USVs) is investigated by employing a distributed model predictive control approach. A hierarchical control structure is considered during the controller design, where the upper layer determines the reference signals of USV velocities while the lower layer optimizes the control inputs of each USV. The main feature of this work is that a post-verification procedure is proposed to address the failure states caused by local errors or cyberattacks. Each USV compares the actual state and the predicted one obtained at the previous moment. This allows the estimation of local perturbations. In addition, the failure state of the USV can also be determined if a preset condition is satisfied, thus forcing a change in the communication topology and avoiding further impact. Simulations show that the proposed method is effective in USV formation control. Compared with the method without post-verification, the proposed approach is more robust when failure states occur.</jats:p

A novel sliding mode speed control–based strategy for permanent magnet linear synchronous motors with a model predictive current control loop

Model predictive control (MPC) has been widely investigated as an advanced control method for permanent magnet linear synchronous motors (PMLSMs). It is known that the computational burden is usually heavy when multi-step MPC is considered. In this paper, a computationally efficient multi-step continuous control set MPC approach is proposed for the current control loop of a PMLSM. A non-singular terminal sliding mode control is employed for the speed control loop to reduce the influence caused by external disturbances. To further improve the closed-loop control performance, a load observer is designed to estimate the load changes in real time. Simulations and experiments reveal the effectiveness of the proposed control method for PMLSMs, which facilitates practical applications