A Robust Hand Silhouette Orientation Detection Method for Hand Gesture Recognition

The computer vision approach is most widely used for research related to hand gesture recognition. The detection of the image orientation has been discovered to be one of the keys to determine its success. The degree of freedom for a hand determines the shape and orientation of a gesture, which further causes a problem in the recognition methods. This article proposed evaluating orientation detection for silhouette static hand gestures with different poses and orientations without considering the forearm. The longest chord and ellipse were the two popular methods compared. The angles formed from two wrist points were selected as ground truth data and calculated from the horizontal axis. The performance was analyzed using the error values obtained from the difference in ground truth data angles compared to the method's results. The method has errors closer to zero that were rated better. Moreover, the method was evaluated using 1187 images, divided into four groups based on the forearm presence, and the results showed its effect on orientation detection. It was also discovered that the ellipse method was better than the longest chord. This study's results are used to select hand gesture orientation detection to increase accuracy in the hand gesture recognition process.

Laser Projector Method for Measuring Postoperative Acetabular Anteversion After Total Hip Replacement

Introduction For patients undergoing total hip replacement (THR), measuring the postoperative acetabular anteversion precisely plays a pivotal role in the prognosis because anteversion of acetabulum cup determines the range of motion and stability after the THR. To date, the documented techniques for the accurate assessment encompass methods of two-dimensional (2D) and three-dimensional (3D). Our team has developed several 2D methods for precisely measuring acetabular anteversion after the THR, namely the trigonometric, the protractor, and the computerized ellipse method. Despite multiple commercially available assessing tools, most mandate computerized equipment with corresponding software that is frequently in shortage in remote areas and developing countries. Therefore, we attempted to invent a laser projector that is able to measure the acetabular anteversion directly on the traditional plain film and to examine its validity and consistency by comparison with the Elliversion software.Methods We invented a portable laser projector incorporating the ellipse method for the measurement of postoperative acetabular anteversion. We retrospectively collected 50 postoperative pelvis radiographs including acetabulum from our institution. One investigator first measured the anteversion of included radiographs through Elliversion software as the control group. Subsequently, two operators independently used the laser projector for measurements in two separate periods with 1-day intervals as the experimental group. Our analysis was comprised of intra- and inter-group comparisons, which investigated the consistency and validity, respectively, by using two-sample student’s t-test. P-value < 0.05 suggests statistical significance. Results There was no significant difference in measuring the anteversion through laser projectors between two operators (MD, -0.12; 95% CI, -0.52 to 0.27; p=0.54). The estimated effect in the anteversion measurement between the Elliversion and laser projector was also comparable (MD, -0.17; 95% CI, -0.38 to 0.04; p=0.12).Conclusions Our study reported the consistency and validity of this laser projector as there is no significant difference in both intra- and inter-observer reliability, demonstrating real-time, intuitive, and convenient product design comparing to Elliversion. Most importantly, we look forward to helping elevate clinical acumen when doctors provide care to patients after THR, especially in remote areas.

A Novel Technique for Radiographic Diagnosis of Sarcopenia that Accurately Predicts Postoperative Complications in Lower Extremity Free Flap Patients

Introduction Sarcopenia is linked to poor outcomes throughout the surgical literature and can be assessed on preoperative imaging to potentially aid in risk stratification. This study examined the effects of sarcopenia on surgical morbidity following lower extremity (LE) reconstruction, and also compared two methods of assessment, one of which is novel (“ellipse method”). Methods A retrospective cohort study of 50 patients receiving free flap-based reconstruction of the LE was performed. Bilateral psoas density and area were quantified at L4 through tracing (“traditional method”) and encircling (“ellipse method”) to calculate Hounsfield unit average calculation (HUAC). Logistic regression and receiving operator curve analysis for the primary outcome of any postoperative complication was used to determine HUAC cutoffs (≤ 20.7 vs. ≤ 20.6) for sarcopenia. Risk of complications associated with sarcopenia was evaluated using Fisher's exact tests. Results Twelve patients (24%) met criteria for sarcopenia via the traditional method and 16 (32%) via the ellipse method. By both methods, sarcopenic patients were older and more often female and diabetic. These patients also had higher American Society of Anesthesiologists scores and lower serum prealbumin levels. The ellipse method was found to be more accurate, sensitive, and specific than the traditional method in predicting postoperative morbidity (p = 0.009). Via the ellipse method, sarcopenic patients were at higher risk for any complication (p = 0.002) and were at a higher risk for a deep vein thrombus or pulmonary embolism via the traditional method (p = 0.047). Conclusion Sarcopenia is associated with greater pre- and postoperative morbidity in LE reconstruction. The novel ellipse method is a simplified and accurate method of assessing sarcopenia that can be easily performed in the clinical setting.

Spatiotemporal Evolution of Multiscale Urbanization Level in the Beijing-Tianjin-Hebei Region Using the Integration of DMSP/OLS and NPP/VIIRS Night Light Datasets

The level of urbanization is a key factor in urban development. In this study, to better characterize the level of urbanization, the panel entropy weight method is used to weight the factors of population, industry, and area to construct a composite indicator of urbanization. A panel regression between this composite index and the average night light values after fusion shows a strong correlation. An accuracy test indicates that the estimated value of fused average light as calculated by the urbanization level estimation model that adequately represents the urbanization level. On this basis, night light data is corrected for zero error on the pixel scale, and spatiotemporal evolution analyses are performed on the city and county scales. The standard deviation ellipse method is used to find that the spatial distribution pattern of the Beijing-Tianjin-Hebei urbanization level from 1995 to 2018 radiates and spreads to the northeast, with Beijing-Tianjin as the center. The spatial pattern shows a contracting trend that is strengthening year by year. Slope analyses show that areas with rapid urbanization growth are mainly concentrated in Beijing and Tianjin. The urbanization development speed of most counties in the Hebei Province is at a low level.

An improved bootstrap method introducing error ellipse for numerical analysis of fatigue life parameters

Purpose The purpose of this paper is to introduce error ellipse into the bootstrap method to improve the reliability of small samples and the credibility of the S-N curve. Design/methodology/approach Based on the bootstrap method and the reliability of the original samples, two error ellipse models are proposed. The error ellipse model reasonably predicts that the discrete law of expanded virtual samples obeys two-dimensional normal distribution. Findings By comparing parameters obtained by the bootstrap method, improved bootstrap method (normal distribution) and error ellipse methods, it is found that the error ellipse method achieves the expansion of sampling range and shortens the confidence interval, which improves the accuracy of the estimation of parameters with small samples. Through case analysis, it is proved that the tangent error ellipse method is feasible, and the series of S-N curves is reasonable by the tangent error ellipse method. Originality/value The error ellipse methods can lay a technical foundation for life prediction of products and have a progressive significance for the quality evaluation of products.

The Spatio-Temporal Characteristics and Influencing Factors of Covid-19 Spread in Shenzhen, China—An Analysis Based on 417 Cases

The global pandemic of COVID-19 has made it the focus of current attention. At present, the law of COVID-19 spread in cities is not clear. Cities have long been difficult areas for epidemic prevention and control because of the high population density, high mobility of people, and high frequency of contacts. This paper analyzed case information for 417 patients with COVID-19 in Shenzhen, China. The nearest neighbor index method, kernel density method, and the standard deviation ellipse method were used to analyze the spatio-temporal characteristics of the COVID-19 spread in Shenzhen. The factors influencing that spread were then explored using the multiple linear regression method. The results show that: (1) The development of COVID-19 epidemic situation in Shenzhen occurred in three stages. The patients showed significant hysteresis from the onset of symptoms to hospitalization and then to diagnosis. Prior to 27 January, there was a relatively long time interval between the onset of symptoms and hospitalization for COVID-19; the interval decreased thereafter. (2) The epidemic site (the place where the patient stays during the onset of the disease) showed an agglomeration in space. The degree of agglomeration constantly increased across the three time nodes of 31 January, 14 February, and 22 February. The epidemic sites formed a “core area” in terms of spatial distribution and spread along the “northwest–southeast” direction of the city. (3) Economic and social factors significantly impacted the spread of COVID-19, while environmental factors have not played a significant role.

Ellipse method for measuring Liaw’s anteversion of the acetabular component after total hip arthroplasty

Background Several cup anteversion measurements for post-operative total hip arthroplasty (THA) surgery have been described. We developed the standardized Liaw’s trigonometric method to eliminate the influence of patient position, which is the most accurate method for cup anteversion measurement. We then developed an ellipse method using the Elliversion software and reported an interobserver error reduction in 2013. In this study, we attempted to apply this ellipse method in the clinic and compared its accuracy with the standard trigonometric version. Methods In the present study, we attempted to incorporate the ellipse method with Liaw’s standardized anteversion in the simulated cup position. We measured standardized Liaw’s anteversion for 434 radiographs in the clinic using the ellipse method. Repeated standard deviation (RSD) was calculated for accuracy evaluation. Furthermore, paired t-test was used for comparison with the interobserver and intraobserver errors. Results We found that the standardized Liaw’s anteversion measured using the ellipse method showed lower RSD than the radiographic version. RSD was 0.795 in the standardized Liaw’s anteversion with ellipse method group. The p-values of the paired t-test were all higher than 0.05 when measuring the interobserver and intraobserver errors. It indicated that the ellipse method was a precise and simple tool for cup anteversion measurement. Conclusion We believe that this ellipse measurement can assist surgeons while placing the acetabulum cup into the precise position and enable early diagnosis of acetabulum loosening.

Ellipse method for measuring Liaw’s anteversion of the acetabular component after total hip arthroplasty

Background: Several cup anteversion measurements for post-operative total hip arthroplasty (THA) surgery have been described. We developed the standardized Liaw’s trigonometric method to eliminate the influence of patient position, which is the most accurate method for cup anteversion measurement. We then developed an ellipse method using the Elliversion software and reported an interobserver error reduction in 2013. In our study, we attempted to apply this ellipse method in the clinic and compared its accuracy with the standard trigonometric version.Methods: In the present study, we attempted to incorporate the ellipse method with Liaw’s standardized anteversion in the simulated cup position. We measured standardized Liaw’s anteversion for 434 radiographs in the clinic using the ellipse method. The Repeatedly Standard Deviation (RSD) was applied for accuracy evaluation. Furthermore, paired t-test was used for comparison with the interobserver and intraobserver errors. Results: We found that the standardized Liaw’s anteversion measured using the ellipse method showed lower repeated standard deviation than the radiographic version. RSD was 0.795 in the standardized Liaw’s anteversion with ellipse method group. The p-values of the paired t-test were all higher than 0.05 when measuring the interobserver and intraobserver bias. It indicated that the ellipse method was a precise and simple tool for cup anteversion measurement. Conclusion: We believe that this ellipse measurement can assist surgeons while placing the acetabulum cup into the precise position and enable early diagnosis of acetabulum loosening.