Synthetic Aperture Imaging of Contact Acoustic Nonlinearity at Closed Interfaces

Ultrasonic imaging has been widely used as an intuitive recognition method for the detection of defects [1]. To enhance the resolution in ultrasound imaging, various kinds of techniques have been developed. Synthetic aperture focusing technique (SAFT) is one of effective post-processing techniques for the resolution improvement. Many studies have shown that SAFT has high resolution as well as high signal to noise ratio for identifying the characteristics of defects accurately [2]. However, most of the imaging techniques based on linear characteristics of ultrasound could underestimate the size of flaws. In particular, the defects in initial state so called micro cracks or closed interfaces are very difficult to be visualized. In order to visualize these micro defects, it is necessary to adopt novel imaging technique using nonlinear ultrasonic characteristics such as contact acoustic nonlinearity (CAN) effect. This study proposed a nonlinear SAFT based on CAN effect and verified its effectiveness. The experiments with array probe for imaging closed interfaces were carried out. The pressure of the interfaces was increased by a hydraulic press, which resulted in the change of the contact state at the interfaces from open interfaces to closed interfaces. When a fundamental ultrasonic wave is incident at closed interfaces, the CAN effect leads the harmonic generation [3]. The proposed synthetic aperture imaging based on CAN effect was applied to visualize the closed interfaces with respect to the change of the contact interface condition. The results showed that SAFT based on CAN effect was effective for the detection of closed interface. This supports that synthetic aperture imaging techniques based on acoustic nonlinearity had advantages for the diagnosis of structural integrity

Effects of informal care on caregivers' labor market outcomes and health in South Korea

This dissertation investigates the effects of informal care on caregiver's labor market outcomes and health in South Korea. Although dramatic demographic transitions in Asian countries have been well documented, less is known about working and caring lives of informal caregivers in this region. Embedded in traditional culture perpetuating family-centered elderly care, informal care still remains invisible as a policy issue. Using newly available microdata from the Korean Longitudinal Study of Aging, this dissertation not only fills the gap in the international literature but also provides evidence to inform current policy debates on elderly long-term care in South Korea. Studies on the two distinct but related outcomes address methodological issues by controlling for the potential endogeneity of informal care, by examining an extensive set of outcome measures, and by employing various functional forms of care intensity. Robust findings suggest negative effects of intensive caregiving on labor force participation, work hours, and wage rates for female caregivers but not for male caregivers. Furthermore, caregivers appear to experience negative mental and physical health outcomes. These findings suggest that informal caregiving is already an important economic and public health issue in South Korea even before the full effects of recent rapid population aging have appeared

Informal Care and Caregiver's Health

This study aims to measure the causal effect of informal caregiving on the health and health care use of women who are caregivers, using instrumental variables. We use data from South Korea, where daughters and daughters‐in‐law are the prevalent source of caregivers for frail elderly parents and parents‐in‐law. A key insight of our instrumental variable approach is that having a parent‐in‐law with functional limitations increases the probability of providing informal care to that parent‐in‐law, but a parent‐in‐law's functional limitation does not directly affect the daughter‐in‐law's health. We compare results for the daughter‐in‐law and daughter samples to check the assumption of the excludability of the instruments for the daughter sample. Our results show that providing informal care has significant adverse effects along multiple dimensions of health for daughter‐in‐law and daughter caregivers in South Korea. Copyright © 2013 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110580/1/hec3012.pd

Synthesis of Eu-doped (Gd,Y) 2 O 3 transparent optical ceramic scintillator

A novel process for transparent oxide ceramic scintillator with a composition of Gd 1.94-x Y x Eu 0.06 O 3 was developed. The process consists of a glycine-nitrate combustion synthesis of nano-sized starting powder and subsequent controlled sintering and annealing steps. The organic molecules remaining in the as-combusted powder were efficiently removed by the combined heat-treatment at vacuum and air atmospheres. Hot-pressed ceramic scintillators show transparent optical state and high light output. Transparent optical ceramic scintillator with a high content of Gd (up to 80 mol%) was fabricated by the process. The measured light output of Gd 1.54 Y 0.4 Eu 0.06 O 3 ceramic scintillator was about two times higher that that of CdWO 4 single crystal. In a typical radiation detection system, the scintillator plays the key role of converting the incident energy of ionizing radiation into scintillation light photons, then the emitted lights are collected by the under-laid photosensor. This specific application requires an ideal scintillator that has high light output, fast decay property, low afterglow, and so forth. Recently, a large number of new scintillator systems has been reviewed, 1 resulting, in part, with the development of a new class of scintillator: the polycrystalline ceramic scintillator

Effects of propofol-remifentanil versus sevoflurane-remifentanil on acute postoperative pain after total shoulder arthroplasty: a randomized trial

Background While some evidence indicates that propofol-based anesthesia has less postoperative pain than sevoflurane-based anesthesia, these results are controversial. We compared acute postoperative pain intensity and opioid consumption after total shoulder arthroplasty between propofol-remifentanil (PR) and sevoflurane-remifentanil (SR) anesthesia. Methods Among 48 patients undergoing shoulder arthroscopic surgery anesthetized with PR or SR, postoperative pain intensity was assessed at 30 minutes and at 2, 6, 12, and 24 hours. The total patient-controlled analgesia volume and number of patients requiring rescue analgesics were assessed. Results No significant difference in postoperative pain intensity was observed between the two groups. Postoperative opioid consumption and analgesic requirements were also comparable in the first 24 hours after surgery. Conclusion PR and SR anesthesia for shoulder arthroscopic surgery provide comparable postoperative analgesia results

Preventive effects of Korean red ginseng on experimentally induced colitis and colon carcinogenesis

© 2020 Center for Food and Biomolecules, National Taiwan UniversityKorean Red Ginseng (KRG) exerts chemopreventive effects on experimentally induced carcinogenesis through multiple mechanisms. In this study, we investigated effects of KRG on dextran sulfate sodium (DSS)-induced colitis and azoxymethane (AOM) plus DSS-induced colon carcinogenesis in mice. Male C57BL/6J mice were fed diet containing 1% KRG or a standard diet throughout the experiment. The mouse colitis was induced by administration of 3% DSS in drinking water for 1 week. DSS caused body weight loss, diarrhea, rectal bleeding and colon length shortening, and all these symptoms were ameliorated by KRG treatment. KRG inhibited DSS-induced expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) by suppressing activation of nuclear factor-kappa B (NF-κB) and signal transducer and activation of transcription 3 (STAT3). In another experiment, colon carcinogenesis was initiated by single intraperitoneal injection of AOM (10 mg/kg) and promoted by 2% DSS in drinking water. KRG administration relieved the symptoms of colitis and reduced the incidence, the multiplicity and the size of colon tumor. The up-regulation of COX-2, iNOS, c-Myc and Cyclin D1 by AOM plus DSS was attenuated in KRG fed mice which was associated with suppression of NF-κB and STAT3 activation. These results suggest that KRG is a potential candidate for chemoprevention of inflammation-associated cancer in the colon.