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The propagation characteristics of Lamb waves in a functionally graded material (FGM) plate with periodic gratings have been studied. The power series technique is employed to solve the governing differential equations with variable coefficients. In the propagation direction, the displacements of Lamb waves are expanded in the Fourier series due to the periodicity of the structure. The convergences of the power series and Fourier series are proved and the method presented in the article is verified by the finite element method (FEM). The band gaps are obtained by the couplings between the different modes of Lamb waves induced by FGM. The effects of the structural parameters (such as the periodicity, mass, and length of the gratings) and gradient coefficient on band gaps are investigated. Numerical results show that the band gaps shift up as the gradient coefficient increases and the second band gap (SBG) is closed when the gradient coefficient is large enough. The conclusions are of practical significance for designing elastic wave filters with high-performance. [ABSTRACT FROM AUTHOR]

AbstractIn this paper, a method is proposed to find the optimal transverse shear function (OTSF) in a specific plate theory. Starting from the polynomial unified framework (PUF) of the transverse shear function, genetic algorithm (GA) has been used to find the best independent parameters in PUF, to obtain the OTSF. Taking the bending of functionally graded rectangular plates as an example, the errors of OTSF and other transverse shear functions are compared. The results show that the error of OTSF is the smallest. The accuracy of plate theory can be controlled by changing the independent parameters in PUF. Therefore, this method is expected to reduce the increasing number of transverse shear functions in new literature. In addition, by studying the results of two plate theories (the difference is whether thickness stretching is considered), it can be concluded that the accuracy of plate theories can be significantly improved by considering the effect of thickness stretching. [ABSTRACT FROM AUTHOR]

Background: Limitations in physicians' knowledge regarding fibrinolytic therapy for acute ischemic stroke may contribute to low rate of fibrinolytic therapy in China. Here physicians' knowledge was surveyed on intravenous fibrinolytic therapy for acute ischemic stroke.Methods: Neurologists (n = 175) from 27 major general hospitals in Shanxi province, P. R. China, were invited to complete questionnaires regarding their basic knowledge of intravenous fibrinolytic therapy for acute ischemic stroke. The questionnaire contained 12 multiple-choice questions. One point was assigned for a correct answer and zero point for a false or unanswered question.Results: One hundred and thirty-one neurologists (74.9%) responded to the questionnaires. The mean accuracy rate of 12 questions was 54.9 ± 25.01% (range 0.8-96.2%). The mean total score for respondents was 6.59 ± 2.03 (range 2-11). More years of experience and higher academic degrees were independent factors related to the total scores (P = 0.000 and P = 0.004, respectively).Conclusions: The neurologists in this study were knowledge deficient in the area of intravenous fibrinolytic therapy for acute ischemic stroke. This partially accounts for the low rate of fibrinolytic therapy in China. [ABSTRACT FROM AUTHOR]

Background: Stroke-associated pneumonia (SAP) is a common complication of cerebrovascular disease. The A2DS2 score has been used to predict the risk of SAP. However, hyperglycemia is not included in this scale. The purpose of the present study was to explore whether the A2DS2 scoring system and hyperglycemia could predict the risk of SAP more effectively than the conventional A2DS2 scale.Methods: This retrospective study enrolled 2552 patients with acute ischemic stroke. The A2DS2 scores, fasting blood glucose level and blood glucose level on admission were collected. Regression analysis was used to identify the independent risk factors of SAP. ROC curve analysis was used to evaluate the specificity and sensitivity of the combined A2DS2 score and fasting hyperglycemia for predicting SAP.Results: Fasting hyperglycemia was an independent risk factor for SAP (OR = 2.95; 95% confidence interval: 2.11-4.12; P < 0.001). The area under curve of the combined A2DS2 score and fasting hyperglycemia was significantly higher than that of the A2DS2 score alone (0.814 vs. 0.793; P = 0.020).Conclusion: Fasting hyperglycemia is an independent risk factor for predicting SAP. Compared with the A2DS2 score, the modified A2DS2 score (combined A2DS2 score and fasting hyperglycemia) is more effective in predicting the risk of SAP. [ABSTRACT FROM AUTHOR]

Purpose: Through three neurocritical care unit (NCCU) surveys in China, we tried to understand the development status of neurocritical care and clarify its future development., Methods: Using a cross-sectional survey method and self-report questionnaires, the number and quality of NCCUs were investigated through three steps: administering the questionnaire, sorting the survey data, and analyzing the survey data., Results: At the second and third surveys, the number of NCCUs (76/112/206) increased by 47% and 84%, respectively. The NCCUs were located in tertiary grade A hospitals or teaching hospitals (65/100/181) in most provinces (24/28/29). The numbers of full-time doctors (359/668/1337) and full-time nurses (904/1623/207) in the NCCUs increased, but the doctor-bed ratio and nurse-bed ratio were still insufficient (0.4:1 and 1.3:1)., Conclusion: In the past 20 years, the growth rate of NCCUs in China has accelerated, while the allocation of medical staff has been insufficient. Although most NCCU hospital bed facilities and instruments and equipment tend to be adequate, there are obvious defects in some aspects of NCCUs., Competing Interests: Dr. Liping Liu is an Editorial Board member of Brain Circulation. The article was subject to the journal’s standard procedures, with peer review handled independently of this Editorial Board member and their research groups., (Copyright: © 2024 Brain Circulation.)