Validity of a commercial wearable sleep tracker in adult insomnia disorder patients and good sleepers

Kang, S.G.,Kang, J.M.,Ko, K.P.,Park, S.C.,Mariani, S.,Weng, J. Pergamon Press 2017 Journal of psychosomatic research Vol.97 No.-

Objectives: To compare the accuracy of the commercial Fitbit Flex device (FF) with polysomnography (PSG; the gold-standard method) in insomnia disorder patients and good sleepers. Methods: Participants wore an FF and actigraph while undergoing overnight PSG. Primary outcomes were intraclass correlation coefficients (ICCs) of the total sleep time (TST) and sleep efficiency (SE), and the frequency of clinically acceptable agreement between the FF in normal mode (FFN) and PSG. The sensitivity, specificity, and accuracy of detecting sleep epochs were compared among FFN, actigraphy, and PSG. Results: The ICCs of the TST between FFN and PSG in the insomnia (ICC=0.886) and good-sleepers (ICC=0.974) groups were excellent, but the ICC of SE was only fair in both groups. The TST and SE were overestimated for FFN by 6.5min and 1.75%, respectively, in good sleepers, and by 32.9min and 7.9% in the insomnia group with respect to PSG. The frequency of acceptable agreement of FFN and PSG was significantly lower (p=0.006) for the insomnia group (39.4%) than for the good-sleepers group (82.4%). The sensitivity and accuracy of FFN in an epoch-by-epoch comparison with PSG was good and comparable to those of actigraphy, but the specificity was poor in both groups. Conclusions: The ICC of TST in the FFN-PSG comparison was excellent in both groups, and the frequency of agreement was high in good sleepers but significantly lower in insomnia patients. These limitations need to be considered when applying commercial sleep trackers for clinical and research purposes in insomnia.

Preparation of the ITER poloidal field conductor insert (PFCI) test

Zanino, R.,Egorov, S.,Kim, K.,Martovetsky, N.,Nunoya, Y.,Okuno, K.,Salpietro, E.,Sborchia, C.,Takahashi, Y.,Weng, P.,Bagnasco, M.,Richard, L.S.,Polak, M.,Formisano, A.,Zapretilina, E.,Shikov, A.,Veder IEEE 2005 IEEE transactions on applied superconductivity Vol.15 No.2

The Poloidal Field Conductor Insert (PFCI) of the International Thermonuclear Experimental Reactor (ITER) has been designed in the EU and is being manufactured at Tesla Engineering, UK, in the frame of a Task Agreement with the ITER International Team. Completion of the PFCI is expected at the beginning of 2005. Then, the coil shall be shipped to JAERI Naka, Japan, and inserted into the bore of the ITER Central Solenoid Model Coil, where it should be tested in 2005 to 2006. The PFCI consists of a NbTi dual-channel conductor, almost identical to the ITER PF1 and PF6 design, ∼45 m long, with a 50 mm thick square stainless steel jacket, wound in a single-layer solenoid. It should carry up to 50 kA in a field of ∼6 T, and it will be cooled by supercritical He at ∼4.5 K and ∼0.6 MPa. An intermediate joint, representative of the ITER PF joints and located at relatively high field, will be an important new item in the test configuration with respect to the previous ITER Insert Coils. The PFCI will be fully instrumented with inductive and resistive heaters, as well as with voltage taps, Hall probes, pick-up coils, temperature sensors, pressure gauges, strain and displacement sensors. The test program will be aimed at DC and pulsed performance assessment of conductor and intermediate joint, AC loss measurement, stability and quench propagation, thermal-hydraulic characterization. Here we give an overview of the preparatory work toward the test, including a review of the coil manufacturing and of the available instrumentation, a discussion of the most likely test program items, and a presentation of the supporting modeling and characterization work performed so far.

A simplified design procedure for seismic retrofit of earthquake-damaged RC frames with viscous dampers

Weng, D.G.,Zhang, C.,Lu, X.L.,Zeng, S.,Zhang, S.M. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.5

The passive energy dissipation technology has been proven to be reliable and robust for recent practical applications. Various dampers or energy dissipation devices have been widely used in building structures for enhancing their performances during earthquakes, windstorm and other severe loading scenarios. This paper presents a simplified seismic design procedure for retrofitting earthquake-damaged frames with viscous dampers. With the scheme of designing the main frame and the supplemental viscous dampers respectively, the seismic analysis model of damped structure with viscous dampers and braces was studied. The specific analysis process was described and approach to parameter design of energy dissipation components was also proposed. The expected damping forces for damped frame were first obtained based on storey shear forces; and then they were optimized to meet different storey drift requirements. A retrofit project of a RC frame school building damaged in the 2008 Wenchuan earthquake was introduced as a case study. This building was retrofitted by using viscous dampers designed through the simplified design procedure proposed in this paper. Based on the case study, it is concluded that this simplified design procedure can be effectively used to make seismic retrofit design of earthquake-damaged RC frames with viscous dampers, so as to achieve structural performance objectives under different earthquake risk levels.

Visualization of Relative Flow Patterns in Centrifugal Blood Pump

Weng Kong Chan,S. C. M Yu,L. P. Chua,Y. W. Wong 대한기계학회 2001 KSME International Journal Vol.15 No.12

A simplified design procedure for seismic retrofit of earthquake-damaged RC frames with viscous dampers

D.G. Weng,C. Zhang,X.L. Lu,S. Zeng,S.M. Zhang 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.44 No.5

The passive energy dissipation technology has been proven to be reliable and robust for recent practical applications. Various dampers or energy dissipation devices have been widely used in building structures for enhancing their performances during earthquakes, windstorm and other severe loading scenarios. This paper presents a simplified seismic design procedure for retrofitting earthquakedamaged frames with viscous dampers. With the scheme of designing the main frame and the supplemental viscous dampers respectively, the seismic analysis model of damped structure with viscous dampers and braces was studied. The specific analysis process was described and approach to parameter design of energy dissipation components was also proposed. The expected damping forces for damped frame were first obtained based on storey shear forces; and then they were optimized to meet different storey drift requirements. A retrofit project of a RC frame school building damaged in the 2008 Wenchuan earthquake was introduced as a case study. This building was retrofitted by using viscous dampers designed through the simplified design procedure proposed in this paper. Based on the case study, it is concluded that this simplified design procedure can be effectively used to make seismic retrofit design of earthquake-damaged RC frames with viscous dampers, so as to achieve structural performance objectives under different earthquake risk levels.

Inelastic Light Scattering Studies of Overdoped Y1-xCaxBa₂Cu₃O₇ Film

J. H. Lin,S. M. Weng,H. L. Liu,P. C. Chung,J.-Y. Lin 한국자기학회 2007 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Theoretically Informed Correlates of Hepatitis B Knowledge among Four Asian Groups: The Health Behavior Framework

Maxwell, Annette E.,Stewart, Susan L.,Glenn, Beth A.,Wong, Weng Kee,Yasui, Yutaka,Chang, L. Cindy,Taylor, Victoria M.,Nguyen, Tung T.,Chen, Moon S.,Bastani, Roshan Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.4

Background: Few studies have examined theoretically informed constructs related to hepatitis B (HBV) testing, and comparisons across studies are challenging due to lack of uniformity in constructs assessed. The present analysis examined relationships among Health Behavior Framework factors across four Asian American groups to advance the development of theory-based interventions for HBV testing in at-risk populations. Methods: Data were collected from 2007-2010 as part of baseline surveys during four intervention trials promoting HBV testing among Vietnamese-, Hmong-, Korean- and Cambodian-Americans (n = 1,735). Health Behavior Framework constructs assessed included: awareness of HBV, knowledge of transmission routes, perceived susceptibility, perceived severity, doctor recommendation, stigma of HBV infection, and perceived efficacy of testing. Within each group we assessed associations between our intermediate outcome of knowledge of HBV transmission and other constructs, to assess the concurrent validity of our model and instruments. Results: While the absolute levels for Health Behavior Framework factors varied across groups, relationships between knowledge and other factors were generally consistent. This suggests similarities rather than differences with respect to posited drivers of HBV-related behavior. Discussion: Our findings indicate that Health Behavior Framework constructs are applicable to diverse ethnic groups and provide preliminary evidence for the construct validity of the Health Behavior Framework.