Blind Yield Detection in Steel Structure for Automatic Nondestructive Testing Using Ultrasonic Sensors

Detection of yield zones using nondestructive testing (NDT) technology for assessing the structural integrity of the existing steel buildings/bridges is extremely important. The average energy over the “effective echoes” (in “good” signal quality) is a robust feature for the yield detection in steel structures. Nevertheless, this average-energy feature extraction requires rigorous manual data-acquisition and human operation. Therefore, in this thesis, we make the first-ever attempt to design a totally-blind and automatic steel-structure yielddetection mechanism, which requires neither the a priori information about the signal nor the human effort in calibration, operation, or data analysis. This new scheme is built upon a robust preprocessor, which involves both blind-signature-signal-extraction and zero-crossingrate thresholding, to identify the starting and terminal time points of each ultrasonic echo. Thus, the new computer-aided system can easily estimate the signal-to-noise ratios and automatically extract the effective echoes to calculate the corresponding average energy. The performance reflected by the receiver-operating characteristic (ROC) curves of the proposed method is very close to that of the conventional human-operating technique. Hence one may save much human effort in the sacrifice of very little detection accuracy by using our proposed new system

Advanced Statistical Signal Processing Methods in Sensing, Detection, and Estimation for Communication Applications

The applications of wireless communications and digital signal processing have dramatically changed the way we live, work, and learn over decades. The requirement of higher throughput and ubiquitous connectivity for wireless communication systems has become prevalent nowadays. Signal sensing, detection and estimation have been prevalent in signal processing and communications for many years. The relevant studies deal with the processing of information-bearing signals for the purpose of information extraction. Nevertheless, new robust and efficient signal sensing, detection and estimation techniques are still in demand since there emerge more and more practical applications which rely on them. In this dissertation work, we proposed several novel signal sensing, detection and estimation schemes for wireless communications applications, such as spectrum sensing, symbol-detection/channel-estimation, and encoder identification. The associated theories and practice in robustness, computational complexity, and overall system performance evaluation are also provided

PTHrP/PTHR1 and TGF-β Levels Are Inversely Associated in Liver Regeneration

Background. Transforming growth factor (TGF)-β provides growth control in liver regeneration. We have recently demonstrated that TGF-β induced parathyroid hormone-related protein (PTHrP) expression and secretion, and PTHrP mediated TGF-β-induced apoptosis in liver cells. However, whether PTHrP signaling pathway is altered during liver regeneration is unknown. Therefore we used a murine hepatectomy model in this study and tested the hypothesis that both PTHrP and TGF-β signaling pathways are upregulated during liver regeneration.    Methods. Swiss Webster mice received 70% hepatectomy or sham operation and euthanized at different time points post-surgery for analyses. Liver regeneration was determined by liver/body weight and proliferating cell nuclear antigen (PCNA) staining. mRNA levels of TGF-β1, TGF-β receptors, PTHrP, and PTHrP receptor 1 (PTHR1) were measured by real-time quantitative PCR. Protein levels of TGF-β1 were measured by ELISA and PTHrP and PTHR1 were measured by Western blotting.      Results. After 70% hepatectomy, the liver regeneration began at 24 hours and was restored to 82% of original liver mass at day 7. TGF-β1 and its receptor levels increased at 24 and 48 hours after hepatectomy, while PTHrP levels decreased at 12 hours and PTHR1 levels decreased at 12, 24 and 48 hours after hepatectomy. The levels of these molecules returned to similar levels as that in sham animals thereafter.    Conclusion. We demonstrated that an upregulation of the TGF-β and its receptors were associated with a down-regulation of PTHrP/PTHR1 expression during liver regeneration, which may contribute to hepatocyte proliferation and regeneration after hepatectomy

Microbiota: A potential orchestrator of antidiabetic therapy

The gut microbiota, as a ‘new organ’ of humans, has been identified to affect many biological processes, including immunity, inflammatory response, gut-brain neural circuits, and energy metabolism. Profound dysbiosis of the gut microbiome could change the metabolic pattern, aggravate systemic inflammation and insulin resistance, and exacerbate metabolic disturbance and the progression of type 2 diabetes (T2D). The aim of this review is to focus on the potential roles and functional mechanisms of gut microbiota in the antidiabetic therapy. In general, antidiabetic drugs (α-glucosidase inhibitor, biguanides, incretin-based agents, and traditional Chinese medicine) induce the alteration of microbial diversity and composition, and the levels of bacterial component and derived metabolites, such as lipopolysaccharide (LPS), short chain fatty acids (SCFAs), bile acids and indoles. The altered microbial metabolites are involved in the regulation of gut barrier, inflammation response, insulin resistance and glucose homeostasis. Furthermore, we summarize the new strategies for antidiabetic treatment based on microbial regulation, such as pro/prebiotics administration and fecal microbiota transplantation, and discuss the need for more basic and clinical researches to evaluate the feasibility and efficacy of the new therapies for diabetes

On Boundedness and Attractiveness of Nonlinear Switched Delay Systems

This paper is concerned with the boundedness and attractiveness of nonlinear switched delay systems whose subsystems have different equilibria. Some sufficient conditions which can guarantee the system's boundedness are obtained. In addition, we work out the region where the solution will remain and furthermore the relationship between the initial function and the bounded region. Based on the new concept of attractor with switching laws, we show that the nonlinear switched delay system is attractive and then obtain the attractive region

Management Strategy for Congenital Choledochal Cyst with Co-existing Intrahepatic Dilation and Aberrant Bile Duct As Well As Other Complicated Biliary Anomalies

The purpose of this study was to investigate and discuss imaging methods and management strategies for congenital choledochal cyst with co-existing intrahepatic dilation and aberrant bile duct as well as other complicated biliary anomalies. In this study we reviewed and analyzed 72 patients with congenital choledochal cyst, ranging in age from 15 days to 12 years old and who were seen at our hospital during the past 12 years, from January 1993 to October 2005. The image manifestation and clinical significance of patients with coxisting intrahepatic biliary dilation and aberrant bile duct were carefully examined during operation via MRCP, cholangiography and choledochoscope. Twenty-two cases (30.1%) presented with intrahepatic bile duct dilation and 12 of these were of the cystic type. That is, the orifice of the dilated intrahepatic tract that converged into the common hepatic duct showed membrane or septum-like stenosis. In 10 cases the dilation tapered off from the porta hepatis to the initiating terminals of the intra-hepatic bile ducts and was not accompanied by stenosis. An aberrant bile duct was observed in 2 of the cases. In 3 cases, the right and left hepatic ducts converged at the choledochal cyst. In conclusion, the imaging methods for intrahepatic bile duct dilation possess important clinical significance. Further, for hepatojejunostomy with radical excision of a choledochal cyst, additional operative procedures for intrahepatic stenosis, possible bile duct malformation and pancreaticobiliary common duct calculi can potentially reduce postoperative complications