Distance Measurements Research Articles

Automated construction of cognitive maps with visual predictive coding

Humans construct internal cognitive maps of their environment directly from sensory inputs without access to a system of explicit coordinates or distance measurements. Although machine learning algorithms like simultaneous localization and mapping utilize specialized inference procedures to identify visual features and construct spatial maps from visual and odometry data, the general nature of cognitive maps in the brain suggests a unified mapping algorithmic strategy that can generalize to auditory, tactile and linguistic inputs. Here we demonstrate that predictive coding provides a natural and versatile neural network algorithm for constructing spatial maps using sensory data. We introduce a framework in which an agent navigates a virtual environment while engaging in visual predictive coding using a self-attention-equipped convolutional neural network. While learning a next-image prediction task, the agent automatically constructs an internal representation of the environment that quantitatively reflects spatial distances. The internal map enables the agent to pinpoint its location relative to landmarks using only visual information.The predictive coding network generates a vectorized encoding of the environment that supports vector navigation, where individual latent space units delineate localized, overlapping neighbourhoods in the environment. Broadly, our work introduces predictive coding as a unified algorithmic framework for constructing cognitive maps that can naturally extend to the mapping of auditory, sensorimotor and linguistic inputs.

Machine learning for parameters diagnosis of spark discharge by electro-acoustic signal

Discharge plasma parameter measurement is a key focus in low-temperature plasma research. Traditional diagnostics often require costly equipment, whereas electro-acoustic signals provide a rich, non-invasive, and less complex source of discharge information. This study harnesses machine learning to decode these signals. It establishes links between electro-acoustic signals and gas discharge parameters, such as power and distance, thus streamlining the prediction process. By building a spark discharge platform to collect electro-acoustic signals and implementing a series of acoustic signal processing techniques, the Mel-Frequency Cepstral Coefficients (MFCCs) of the acoustic signals are extracted to construct the predictors. Three machine learning models (Linear Regression, k-Nearest Neighbors, and Random Forest) are introduced and applied to the predictors to achieve real-time rapid diagnostic measurement of typical spark discharge power and discharge distance. All models display impressive performance in prediction precision and fitting abilities. Among them, the k-Nearest Neighbors model shows the best performance on discharge power prediction with the lowest mean square error (MSE = 0.00571) and the highest -squared value ( ). The experimental results show that the relationship between the electro-acoustic signal and the gas discharge power and distance can be effectively constructed based on the machine learning algorithm, which provides a new idea and basis for the online monitoring and real-time diagnosis of plasma parameters.

"Scleroderma" and "Scleroderma-like" Capillaroscopic Pattern-Differences and Similarities.

The "scleroderma" type capillaroscopic pattern is a reference pattern in rheumatology that is a diagnostic sign for systemic sclerosis (SSc) in an appropriate clinical context and is observed in more than 90% of scleroderma patients. Similar microvascular changes, the so-called "scleroderma-like", have been described albeit in a lower proportion of patients with other rheumatic diseases, such as dermatomyositis (DM), undifferentiated connective tissue diseases (UCTD), systemic lupus erythematosus (SLE), etc. Three distinct stages of "scleroderma" pattern have been suggested by Cutolo et al., i.e., "early", "active", and "late". However, disease duration is just one of the factors that contributes to the progression of microvascular changes, and in this regard, "active" or even "late" pattern could be observed in patients with shorter disease duration. In addition, stable microvascular changes could be found for long periods in other cases. The aim of the study was to assess the presence of differentiating features between "scleroderma" pattern in SSc and "scleroderma-like" pattern in other rheumatic diseases. 684 capillaroscopic images demonstrating a "scleroderma" and "scleroderma-like" pattern have been analysed in the current retrospective cross-sectional study. 479 capillaroscopic pictures were obtained from 50 SSc patients, 105 from 7 DM patients, 38 from 10 rheumatoid arthritis (RA) patients, 36 images from 5 patients with SLE, and 26 images from 9 patients with UCTD. All capillaroscopic images used in the current analysis have fulfilled the criteria for "sclerderma/scleroderma-like" pattern, as the pathological changes in the capillaroscopic parameters have also been confirmed by quantitative measurement of capillary diameters, capillary density, and intercapillary distance. All the images have been categorized into one of the following groups, i.e., "early", "active" and "late" phases (according to the definition of Cutolo et al.), or "other" findings, the latter being specifically described as they could not be attributed to one of the other three categories. 479 capillaroscopic pictures were obtained from 50 scleroderma patients. 31 of them showed an "early", 391 an "active" phase, and 57 a "late" phase "scleroderma" type microangiopathy. In 69 images assessed as an "active" pattern, neoangiogenesis was found. In 43 out of 105 capillaroscopic pictures from DM patients, an "active" phase was detected; in 2 of the images, a "late" pattern was found, and in 60 capillaroscopic pictures, neoangiogenesis in combination with giant capillary loops was observed. Early microangiopathy was not found in this group. Among capillaroscopic images from SLE patients, "late" phase microangiopathy was not found. "Early" phase was present in 3 images, "active" phase in 29, neoangiogenesis in "active" phase in 4 pictures. Early microangiopathy was detected in 11 capillaroscopic pictures from RA patients (8 out of 9 patients), an "active" phase in 4 images (3 patients), and in 23 capillaroscopic images, neoangiogenesis with mild capillary derangement and capillary loss and single giant capillaries ("rheumatoid neoangiogenic pattern") were observed. Classic "late" type microangiopathy was not found in RA patients as well as among patients with UCTD. The predominant capillaroscopic pattern in UCTD patients was early microangiopathy (n = 23). The rest images from UCTD exhibited features of the "active" phase. In conclusion, early microangiopathy was observed in RA, SLE, and UCTD patients, but not in patients with DM. An "active" phase "scleroderma" type capillaroscopic pattern was detected in all patient groups other than SSc, i.e., DM, SLE, RA, and UCTD. "Late" phase "scleroderma" type microangiopathy was present in patients with scleroderma and DM and was not observed in SLE, RA, and UCTD. Despite the fact that in some cases, microangiopathy in scleroderma and other rheumatic diseases may be indistinguishable, the results of the current research have shown the presence of some differentiating features between "scleroderma" and "scleroderma-like" microangiopathy that might be a morphological phenomenon associated with differences in the pathogenesis and the degree of microvascular pathology in various rheumatic diseases.

Starspots and Undetected Binary Stars Have Distinct Signatures in Young Stellar Associations

Young stars form in associations, meaning that young stellar associations provide an ideal environment to measure the age of a nominally coeval population. Isochrone fitting, which is the typical method for measuring the age of a coeval population, can be impacted by observational biases that obscure the physical properties of a population. One feature in isochrone fits of star-forming regions is an apparent mass-dependent age gradient, where lower-mass stars appear systematically younger than higher-mass stars. Starspots and stellar multiplicity are proposed mechanisms for producing the mass-dependent age gradient, but the relative importance of starspots versus multiplicity remains unclear. We performed a synthetic red optical low-resolution spectroscopic survey of a simulated analog to a 10 Myr stellar association including mass-dependent multiplicity statistics and age-dependent starspot coverage fractions. We found that undetected starspots alone do not produce an apparent mass-dependent age gradient, but instead uniformly reduce the average measured age of the population. We also found that binaries continue to produce an apparent mass-dependent age gradient and introduce more scatter in the age measurement than spots, but are easily removed from the population as long as there are good distance measurements to each target. We conclude that it is crucial to incorporate treatments of both starspots and undetected stellar multiplicity into isochrone fits of young stellar associations to attain reliable ages.

A census of new globular clusters in the Galactic bulge

Context. The number of known globular clusters in the Galactic bulge has been increasing steadily thanks to different new surveys. Aims. The aim of this study is to provide a census of the newly revealed globular clusters in the Galactic bulge, and analyze their characteristics. Methods. In recent years, many globular clusters have been discovered or identified. The stellar populations to which they belong are indicated in their original studies: they are mostly bulge clusters, with some identified as disk or halo members. We collected 41 new globular clusters revealed in the last decade and compared them to the known bulge clusters. Results. The new clusters are intrinsically faint with MV of around −6.0 mag. The distance to the Sun of the ensemble of well-known and new bulge clusters is compatible with the Galactocentric distance measurements from the Galactic black hole location. The ensemble sample shows metallicity peaks at [Fe/H] ∼ −1.08 ± 0.35 and −0.51 ± 0.25 dex, confirming previous findings. The age–metallicity relation of the new clusters younger than 10 Gyr is compatible with that of the ex situ samples of the dwarf galaxies Sagittarius, Canis Majoris, and Gaia-Enceladus-Sausage. The clusters with ages between 11.5 and 13.5 Gyr show no age–metallicity relation, because they are all old. This is compatible with their formation in situ in the early Galaxy.

Constraints from Parallaxes and Average Period Spacings in the Asteroseismic Study of Eight Hydrogen-atmosphere Pulsating White Dwarfs

With space missions such as Kepler, TESS, and Gaia, we have a wealth of data on pulsating white dwarfs that can be leveraged in white dwarf asteroseismology. We address the question of the proportion of white dwarfs with thin hydrogen layers versus those with thick hydrogen layers. We also provide a mass–radius relation for carbon–oxygen-core, hydrogen-atmosphere white dwarfs. Such a relationship can be used in conjunction with magnitudes and distance measurements to constrain the mass and effective temperature of the white dwarfs. We select nine hydrogen-atmosphere pulsating white dwarfs for their rich pulsation spectra. From such pulsation spectra, we can derive the asymptotic period spacing, which in turn allows us to determine the thickness of the hydrogen and helium envelope of the models, without having to perform period-by-period fitting. We find that the majority of the white dwarfs have thicker hydrogen layers and we determine an upper limit of M r = 1–10−2.2 for the location of the base of the helium layer, in accordance with stellar evolution models. We confirm a finding from earlier studies that used a mass–radius relation and Gaia data to determine the effective temperatures of white dwarfs. The Gaia data systematically point to white dwarfs of lower effective temperature than indicated by the spectroscopy. Our results also support the hypothesis that white dwarfs with thicker hydrogen layers are more common than those with thinner layers.

Ultrasonic Sensor-based Water Leveling for Three-dimensional Water Phantom: Prototype Development.

The purpose of this study was to develop a prototype for controlling the water level of a three-dimensional (3D) water phantom using ultrasound sensors and Arduino technology and evaluate its performance in setting up the 3D water phantom for radiation beam measurements. A prototype consisted of an Arduino Nano board and two types of ultrasound sensors (US015 and SR04). The accuracy of both sensors was tested at various distances and the performance was evaluated through statistical analysis. The distance measurement test was performed rigorously at intervals of 2 cm from 5 cm to 21 cm, measuring an average error and a maximum deviation for each sensor. Both sensors demonstrated the measurement accuracy within 2 mm. When using the traditional and prototype-based setup methods, the measured photon and electron beam profiles did not show any significant difference. This result suggests the equivalent setup capability when using these two different 3D water phantom setup methods. The ultrasound sensor-based prototype is demonstrated as a more effective device in maintaining the 3D water phantom setup consistently compared to the traditional method, which is prone to human error, and it will aid in facilitating precise phantom setup during the commissioning and routine quality assurance (QA) of linear accelerators in radiotherapy clinics.

Method for noninvasive HV/MV switchgear motion analysis using kernel-based algorithm with adaptive feature extraction

When designing, developing, and testing medium-voltage (MV) and high-voltage (HV) switchgears, it is of utmost importance to analyze the movements of their mechanical parts, such as drive trains, contact nozzles, etc. This ensures the safety of switchgear operations and enables detecting and predicting issues that could lead to component damage, power interruptions, reduced efficiency, or even switch failure. Conventional invasive measuring setups, including encoders and laser distance measurements, are often difficult or expensive to use, due to undesirable environmental properties such as high temperatures and/or high voltages, or dimensional constraints often encountered in testing laboratories, compact substations or confined equipment rooms. Video object tracking can be a viable solution in such conditions, allowing for the extraction of the trajectory of mechanical parts of an object under analysis. This paper proposes a novel kernel-based algorithm with adaptive feature extraction for precise colour-based object tracking through video processing. The implemented method is based on the principles of the CamShift algorithm, augmented with fusion with the Kalman filter for continuous estimation and prediction of the object’s position based on the available measurements while reducing sensitivity to noise. Beyond precise tracking of the object of interest, the algorithm automatically adapts the mask used in the standard CamShift algorithm by extracting and processing the features of the selected object. This approach exhibits flexibility and robustness in adverse industrial environments. It supports modifications according to user preferences and represents a cost-effective alternative to conventional methods, while performing real-time processing. Experimental results underscore this noninvasive approach is flexible, highly robust, and enables tracking of coloured markers even in challenging conditions like poor lighting, significant blur, and low frame rates.

First constraints on non-minimally coupled Natural and Coleman-Weinberg inflation and massive neutrino self-interactions with Planck+BICEP/Keck

In this work, for the first time in literature, we study the predictions of non-minimally coupled Natural and Coleman-Weinberg potentials in the ns -r plane, and an extended ΛCDM model where we include non-standard self-interactions among massive neutrinos, mediated by a heavy scalar or vector boson. Constraints were derived using the Planck 2018 + BICEP/Keck 2018 datasets along with other data. For the inflationary potentials, we consider two different formulations in gravity that are non-minimally coupled to the scalar field of the inflaton: Metric and Palatini. We only consider the self-interaction to be present among τ-neutrinos and only at moderate strengths. This is because strong interactions among τ-neutrinos, or any strength self-interaction among electron- and muon-neutrinos, as well as any strength flavor-universal interactions, are strongly disfavoured from particle physics experiments.In terms of cosmological data, we use the latest public CMB datasets from Planck 2018 and BICEP/Keck 2018 collaborations, along with other data from CMB lensing, BAO, RSD, and SNe Ia luminosity distance measurements. We find that there are some situations where predictions from the inflationary models are ruled out at more than 2σ by the minimal ΛCDM+r model, but they are allowed in the self-interacting neutrino scenario.

Guided-wave Dynamic Probability Model-based Crack Quantification Method for Metal Structures

In the process of applying guided-wave-based aircraft online structural health monitoring, the characteristics of guided wave signals used to represent structural status exhibit random uncertainty due to the interference of loads on guided wave propagation. The trend of signal feature changes caused by damage is often obscured, making the quantification of cracks under loads one of the challenges in online structural health monitoring for aircraft. To address this challenge, this paper proposes a crack quantification method using an adaptive Gaussian mixture model (GMM) and optimized probability migration distance measurement. This method effectively mitigates the uncertainty caused by loads by constructing an adaptive Gaussian mixture model to track the probability distribution changes of guided wave signal features under different structural health conditions. Subsequently, an optimized probability migration distance measurement method is employed to characterize the structural state, further enhancing the correlation between features and the extent of structural damage. Finally, an optimized probability migration distance relationship with crack length is established to estimate the crack length of new structural specimens. The effectiveness of this method is validated using load-induced crack propagation experiments on metal structures.

YOLOv3 Based Smart Assistive Navigation System for Visually Impaired Individuals

Abstract: Nowadays, some people suffer from blindness or vision impairment, either from childhood or due to other causes. These individuals frequently face difficulty to move from source to destination precisely, resulting in difficulties in their daily routines. Currently, people are using normal walking sticks, that is not useful for all the time, especially in outdoor environments, resulting in accidents and other difficulties. This paper aims to focus on improving the quality of life for blind people or visually impaired individuals by providing a suitable solution to enhance navigation and manage their needs in indoor and outdoor environments through the use of wearable devices. One proposed solution involves the method of voice assistant technology, which allows users to easily communicate and receive clear instructions. The Raspberry Pi camera module, that allows to capture images and video streaming with the Raspberry Pi, where the Ultrasonic sensor is commonly used for distance measurement to detect obstacles. Furthermore, incorporating a Neo 6m GPS module offers precise location data and navigation guidance, aiding users in reaching their destination safely and efficiently.

TRENDS OF THE MICROWAVE PHOTONIC RADARS

Today, the world's leading countries are intensively working on the development of new generation radars - microwave photonic radars. Microwave photonic radars make it possible to significantly reduce the mass and size characteristics of radar stations, to increase the information capability and range of target detection due to the reduction of losses in long communication lines when using optical fiber, to ensure high immunity due to the significantly lower sensitivity of optical-electronic equipment and fiber-optic lines of communication connection to external electromagnetic influences. Microwave photonics provides wide bandwidth, flat response, low loss transmission, multi-dimensional multiplexing, ultra-fast analog signal processing and immunity to electromagnetic interference. Radar implementation in the optical domain can provide better resolution, coverage, and speed performance, which would be difficult to implement with traditional electronics. The review article examines the state of development and system architectures of such photonic radars as optoelectronic hybrid radars, all-optical radars, multifunctional microwave photonic radar systems, distributed microwave photonic radars, software-defined radars, and cognitive radars. New technologies in this field and possible future directions of research are discussed. As an example, a broadband microwave photon radar reproduced on the basis of a microcircuit is considered. The broadband signal generator and receiver are built into the silicon crystal on the insulator. A high-precision distance measurement with a resolution of 2.7 cm and an error of less than 2.75 mm was obtained. Visualization of multiple targets with complex profiles has been implemented. But the performance of most integrated microwave photonic chips is not yet satisfactory for practical radar applications. Monolithic integration of key microwave photonic subsystems is also not mature enough for practical applications, so hybrid integration of devices fabricated on their optimal integration platforms is of practical interest. At present, indium phosphide, silicon nitride and silicon on insulator are the three leading platforms for photonic integration

Pre- and Post-Operative Cone Beam Computed Tomography Assessment of the Temporomandibular Joint in Patients with Orthognathic Surgery.

This study aimed to compare the pre- and post-operative temporomandibular joint (TMJ) condylar position in dentofacial deformity (DFD) patients who had orthognathic surgeries using cone beam computed tomography (CBCT). A retrospective study evaluating the pre- and post-operative CBCT for 79 DFD patients (equivalent to 158 TMJs) (mean age = 26.62 ± 9.5 years) with a bilateral sagittal split osteotomy with or without Le Fort I surgeries (n = 29 Class II DFD, n = 50 Class III DFD) was performed. This included the compartmental measurement of TMJ spaces, in addition to the measurement of intercondylar distances and angles. Condylar position centricity was assessed using the Pullinger and Hollender formula. Clinical data were analysed for DFD class, the type of surgery and post-operative CBCT timing. Pre- and post-operative measurements were compared statistically using a paired t-test, Wilcoxon signed-rank test, and Stuart-Maxwell test. TMJ condyles tended to relocate post-operatively in a posterosuperior position with internal rotation in Class II DFD and a superior position with internal rotation in Class III DFD. However, the overall changes were within <0.5 mm translation and <4° rotation and the number of concentrically positioned condyles (according to the Pullinger and Hollender formula) did not change significantly. Orthognathic surgery is associated with minor post-operative translational and rotational condylar positional changes in Class II and III DFDs.

Autonomous wireless positioning system using crowdsourced Wi-Fi fingerprinting and self-detected FTM stations

Wi-Fi positioning system (WPS) has been proven as an effective way to realize universal indoor navigation for smart city-related applications. The localization ability of the existing WPS is affected by the low precision of the crowdsourced database and the unknown location of local wireless stations. This paper develops an integrated indoor localization framework using crowdsourced Wi-Fi fingerprinting and self-detected Wi-Fi Fine Time Measurement (FTM) stations (IL-CFSW). A novel crowdsourced mobile sensors data modeling algorithm with self-calibrated parameters is proposed, and modeled trajectories are further segmented and matched with the existing pedestrian indoor network to enhance the performance of the final database generation. Furthermore, the iteration unscented Kalman filter (iUKF) is adopted to recognize the position and calibrate the bias of existing Wi-Fi FTM anchors combined with the hybrid distance measurement model. Finally, an enhanced particle filter with error ellipse constraint is developed to fuse different location sources and indoor network information. Comprehensive experimental results present that the developed IL-CFSW can achieve autonomous 3D indoor localization performance in multi-floor contained scenes and meter-level positioning accuracy is achieved with the consideration of pedestrian indoor network information.

An efficient EPR spin-labeling method enables insights into conformational changes in DNA

Electron paramagnetic resonance (EPR) is a powerful tool for elucidating both static and dynamic conformational alterations in macromolecules. However, to effectively utilize EPR for such investigations, the presence of paramagnetic centers, known as spin labels, is required. The process of spin labeling, particularly for nucleotides, typically demands intricate organic synthesis techniques. In this study, we introduce a unique addition-elimination reaction method with a simple spin-labeling process, facilitating the monitoring of structural changes within nucleotide sequences. Our investigation focuses on three distinct labeling positions with a DNA sequence, allowing the measurement of distance between two spin labels. The experimental mean distances obtained agreed with the calculated distances, underscoring the efficacy of this straightforward spin-labeling approach in studying complex biological processes such as transcription mechanism using EPR measurements.

ENGINEERING-GEODETIC SURVEYING. GEOMETRIC LEVELING OF THE ROUTE

The purpose of leveling the route is to determine the elevations of all the control points, including the beginning, middle, and end of curves, plus points, and points on transverse profiles. Longitudinal and transverse leveling is carried out after the route has been set out. The results of leveling (elevation measurements) are subsequently used for constructing the longitudinal profile of the route and the transverse profiles.The paper outlines the main principles and methods of leveling, taking leveling readings on rods, referencing the road route to benchmarks, leveling junction and intermediate points, balancing elevation differences, and calculating junction and intermediate points. The paper also describes the control of route leveling and plotting the projected line on the longitudinal profile.Engineering-geodetic surveying, specifically geometric leveling of the route, is an important component of educational geodetic practice. Geodetic practice for students is conducted according to the academic curriculum and serves as a continuation of the learning process in the field. It completes the theoretical course and is conducted according to the academic plan. During practical training, students acquire skills in working with geodetic instruments and processing the results of field measurements, becoming familiar with the main types of engineering-geodetic work during surveys and construction of engineering structures. Students are required to participate in all types of work, conduct the necessary measurements, and process them in the office. Practical training in geodetic practices provides students with hands-on experience in applying theoretical knowledge to real-world scenarios. Through fieldwork, students gain proficiency in using a variety of geodetic instruments such as levels, total stations, and GPS receivers. They learn how to set up and operate these instruments accurately to collect precise measurements of elevation and distance. Furthermore, students learn the importance of teamwork and collaboration during field surveys. Working together with peers, they divide tasks, communicate effectively, and problem-solve on-site challenges that may arise. These collaborative experiences not only enhance their technical skills but also cultivate essential soft skills such as leadership, communication, and adaptability.

Radiographic calibration for pubic diastasis assessment in bladder exstrophy-epispadias complex: a phantom study

BackgroundThe assessment of pubic diastasis is important for the surgical planning of patients with bladder exstrophy-epispadias complex. Understanding how the diastasis changes during surgical follow-up may help predict patient morbidity. Radiography can follow diastasis but may be affected by patient and technical imaging factors including body size, imaging protocol, and equipment. Using imaging calibration and anatomic ratios may mitigate differences due to these aspects.ObjectiveUse imaging phantoms to assess the effect of radiographic calibration on measurements of pubic diastasis and an internal anatomic ratio as a child grows.Materials and methodsRadiographic images were obtained of three different sizes of computed tomography phantoms (older child, child, and infant) using three imaging techniques that include the osseous pelvis in children. All phantoms were imaged with abdomen and pelvis techniques. The infant phantom was additionally imaged using a thoracoabdominal technique. These exposures were all repeated with systems from three manufacturers. Linear measurements were made between radiographic markers placed to simulate pubic diastasis and sacral width. A ratio was also created between these distances. Measurements with and without image calibration were made by two pediatric radiologists using rulers placed at the time of image acquisition.ResultsThere was excellent interrater agreement for measurements, ICC >0.99. Anterior distances were more affected by magnification than posterior ones with a significant difference between uncalibrated versus calibrated anterior distances (p=0.04) and not for posterior ones (p=0.65). There was no difference between radiographic equipment manufacturers without or with calibration (p values 0.66 to 0.99). There was a significant difference in simulated pubic distance between thoracoabdominal and abdomen (p=0.04) as well as pelvic (p=0.04) techniques which resolved with calibration, each p=0.6. The ratio between the simulated pubic diastasis and sacral width differed by phantom size (all p<0.01) and imaging technique (p values 0.01 to 0.03) with or without calibration. However, the numerical differences may not be clinically significant.ConclusionImage calibration results in more uniform measurements that are more accurate than uncalibrated ones across patient size, imaging techniques, and equipment. Image calibration is necessary for accurate measurement of inter-pubic distances on all projection imaging. Small differences in the pelvic ratio likely are not clinically significant, but until there is a better understanding, image calibration may be prudent.Graphical abstract

Inertial Measurement Unit and Heart Rate Monitoring to Assess Cardiovascular Fitness of Manual Wheelchair Users during the Six-Minute Push Test.

Manual wheelchair users (MWUs) are prone to a sedentary life that can negatively affect their physical and cardiovascular health, making regular assessment important to identify appropriate interventions and lifestyle modifications. One mean of assessing MWUs' physical health is the 6 min push test (6MPT), where the user propels themselves as far as they can in six minutes. However, reliance on observer input introduces subjectivity, while limited quantitative data inhibit comprehensive assessment. Incorporating sensors into the 6MPT can address these limitations. Here, ten MWUs performed the 6MPT with additional sensors: two inertial measurement units (IMUs)-one on the wheelchair and one on the wrist together with a heart rate wristwatch. The conventional measurements of distance and laps were recorded by the observer, and the IMU data were used to calculate laps, distance, speed, and cadence. The results demonstrated that the IMU can provide the metrics of the traditional 6MPT with strong significant correlations between calculated laps and observer lap counts (r = 0.947, p < 0.001) and distances (r = 0.970, p < 0.001). Moreover, heart rate during the final minute was significantly correlated with calculated distance (r = 0.762, p = 0.017). Enhanced 6MPT assessment can provide objective, quantitative, and comprehensive data for clinicians to effectively inform interventions in rehabilitation.

Risk factors for preoperative neurological impairment in patients with spinal meningioma: A retrospective multicenter study

BackgroundPatients with spinal meningioma may present preoperatively with paralysis and sensory deficits. However, there is a paucity of detailed evaluations and a lack of consensus regarding imaging findings that are predictive of neurological symptoms in patients with spinal meningioma. MethodsHerein, a total of 55 patients who underwent surgical resection of spinal meningiomas in eight hospitals between 2011 and 2021 were enrolled. Patient characteristics, degree of muscle weakness, sensory disturbances, and the presence of bowel/bladder dysfunction (BBD) before surgical treatment were evaluated using medical records. Patients with American Spinal Injury Impairment Scale grades A-C and the presence of BBD were classified into the paralysis (+) group. Patients with sensory disturbances were assigned to the sensory disturbance (+) group. Based on magnetic resonance (MR) and computed tomography images, the tumor location was classified according to the spinal level and its attachment to the dura mater. To evaluate tumor size, the tumor occupation ratio (OR) was calculated using the area and distance measurement method in horizontal MR images, and the maximum length and area of the tumor in the sagittal plane were measured. ResultsOf all patients, 85 % were women. The mean age of patients at surgery was 69.7 years. Twenty-eight (51 %) and 41 (75 %) patients were classified into the paralysis (+) and sensory disturbance (+) groups, respectively. The average tumor length and area in the sagittal plane were 19.6 mm and 203 mm2, respectively; OR-area and diameters were 70.3 % and 72.3 %, respectively. In univariate analyses, tumor length and area in the sagittal plane were significant risk factors for paralysis. OR-diameter, symptom duration, and a low MIB-1 index correlated with sensory disturbances. Multivariate logistic regression analysis demonstrated that the area and length of the tumor in the sagittal plane were significantly correlated with paralysis, whereas the OR-diameter and symptom duration significantly correlated with sensory disturbances. The cut-off values for the area and length of the tumor in the sagittal plane to predict paralysis were 243 mm2 and 20.1 mm, respectively. ConclusionsPreoperative paralysis in patients with spinal meningiomas was significantly associated with sagittal tumor size than with high tumor occupancy in the horizontal plane. Sensory disturbances were associated with high occupancy in the horizontal plane. Patients with spinal meningiomas > 20 mm in length or 243 mm2 in area in the sagittal plane are at risk of developing paralysis and could be considered for surgery even in the absence of paralysis.

Design and Implementation of an Intelligent Ultrasonic System based on 51 Microcontroller

With the rapid development of microelectronics and intelligent technology, microcontroller units (MCUs) are increasingly applied in various fields. This paper proposes the design and implementation of an intelligent ultrasonic system based on a 51 microcontroller, integrating ultrasonic sensors, an LCD display, and a 51 MCU to achieve real-time distance measurement, data display, and intelligent control functions. The system utilizes a CD4069 ultrasonic sensor to transmit and receive ultrasonic waves, measuring the distance between the sensor and an object by calculating the time difference between transmission and reception. The measured distance data is processed and displayed on an LCD screen in real-time. Furthermore, the system features intelligent control capabilities, automatically adjusting and controlling devices based on the measured data, thereby enhancing the system's level of intelligence. The intelligent ultrasonic system based on the 51 microcontroller offers advantages such as low cost, high precision, and strong versatility. It can be widely used in various fields, including intelligent robots, obstacle avoidance systems, and automatic parking systems. The design and implementation of this system not only demonstrate innovative applications of ultrasonic ranging technology but also provide valuable references for the extensive application of microcontroller units in intelligent technology fields.