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排序方式: 共有810条查询结果,搜索用时 15 毫秒
101.
Dajani HR Purcell D Wong W Kunov H Picton TW 《IEEE transactions on bio-medical engineering》2005,52(9):1614-1618
We investigated whether pitch-synchronous neural activity could be recorded in humans, with a natural vowel and a vowel in which the fundamental frequency was suppressed. Small variations of speech periodicity were detected in the evoked responses using a fine structure spectrograph (FSS). A significant response (P < 0.001) was measured in all seven normal subjects even when the fundamental frequency was suppressed, and it very accurately tracked the acoustic pitch contour (normalized mean absolute error < 0.57%). Small variations in speech periodicity, which humans can detect, are therefore available to the perceptual system as pitch-synchronous neural firing. These findings suggest that the measurement of pitch-evoked responses may be a viable tool for objective speech audiometry. 相似文献
102.
Ultrasonic cavitation was employed to enhance sensitivity of bacterial spore immunoassay detection, specifically, enzyme-linked immunosorbent assay (ELISA) and resonant mirror (RM) sensing. Bacillus spore suspensions were exposed to high-power ultrasound in a tubular sonicator operated at 267 kHz in both batch and flow modes. The sonicator was designed to deliver high output power and is in a form that can be cooled efficiently to avoid thermal denaturation of antigen. The 30-s batch and cooled flow (0.3 mL/min) sonication achieved an approximately 20-fold increase in ELISA sensitivity compared to unsonicated spores by ELISA. RM sensing of sonicated spores achieved detection sensitivity of approximately 10(6) spores/mL, whereas unsonicated spores were undetectable at the highest concentration tested. Improvements in detection were associated with antigen released from the spores. Equilibrium temperature increase in the tubular sonicator was limited to 14 K after 30 min and was maintained for 6 h with cooling and flow (0.3 mL/min). The work described here demonstrates the utility of the tubular sonicator for the improvement in the sensitivity of the detection of spores and its suitability as an in-line component of a rapid detection system. 相似文献
103.
104.
Keane Terence M.; Martin John E.; Berler Ellen S.; Wooten Laura S.; Fleece E. Louis; Williams James G. 《Canadian Metallurgical Quarterly》1982,50(4):499
Assessed the performance of 12 male hypertensives (mean age 47.36 yrs) in increasingly demanding interpersonal interactions. 12 extended role-played scenes incorporating the expression of positive and negative emotional states were used. Behavioral, physiological, and subjective ratings were obtained. Performance of the hypertensives was compared to that of both patient and nonpatient normotensive Ss who were carefully matched with the hypertensives on a number of demographic variables. Results indicate that the hypertensives responded less assertively on a number of dimensions than did the nonpatient comparison group. However, the performance of the normotensive patient group was similar to that of the hypertensive patients. Physiological and subjective data indicated comparable responding across all 3 experimental groups. The discussion focuses on the existence of a chronic-illness syndrome that potentially has strong behavioral correlates. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
105.
Wickramasekera Ian; Davies Terence E.; Davies S. Margaret 《Canadian Metallurgical Quarterly》1996,27(3):221
Over half of all patient visits to primary care physicians are related to psychosocial problems that are presented as common somatic complaints. It appears that psychophysiological diagnostic and therapeutic methods can directly, objectively, and quantitatively reveal this missing mind–body connection. Psychophysiological methods, including biofeedback, hypnosis, and cognitive behavior therapy have been shown to be empirically effective with several somatic conditions even though the specific mechanisms of efficacy of these therapies have not been identified. The classification, diagnosis, prevention, and therapy of stress-related disease and somatization disorder require a psychophysiological approach and can most effectively be conducted in a nonpsychiatric primary care setting. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
Minoru Furukawa Patrick B. Berbon Terence G. Langdon Zenji Horita Minoru Nemoto Nikolai K. Tsenev Ruslan Z. Valiev 《Metallurgical and Materials Transactions A》1998,29(1):169-177
Experiments were conducted to determine the age-hardening characteristics and the mechanical properties of an Al-5.5 pct Mg-2.2
pct Li-0.12 pct Zr alloy processed by equal-channel angular (ECA) pressing to give a very fine grain size of ∼1.2 μm. The results show that peak aging occurs more rapidly when the grain size is very fine, and this effect is interpreted in
terms of the higher volume of precipitate-free zones in the fine-grained material. Mechanical testing demonstrates that the
ECA-pressed material exhibits high strength and good ductility at room temperature compared to conventional Al alloys containing
Li. Elongations of up to ∼550 pct may be achieved at an elevated temperature of 603 K in the ECA-pressed condition, thereby
confirming that, in this condition, the alloy may be a suitable candidate material for use in superplastic forming operations. 相似文献
107.
Mohammed Smadi Terence D. Todd Vytas Kezys Vahid Azhari Dongmei Zhao 《Wireless Networks》2008,14(6):815-829
In this paper we consider vertical handoff for enterprise-based dual-mode (DM) cellular/WLAN handsets. When the handset roams
out of WLAN coverage, the DM's cellular interface is used to maintain the call by anchoring it through an enterprise PSTN
gateway/PBX. Soft handoff can be achieved in this case if the gateway supports basic conference bridging, since a new leg
of the call can be established to the conference bridge while the existing media stream path is active. Unfortunately this
requires that all intra-enterprise calls be routed through the gateway when the call is established. In this paper we consider
a SIP based architecture to perform conferenced dual-mode handoff and propose a much more scalable mechanism for short-delay
environments, whereby active calls are handed off into the conference bridge prior to the initiation of the vertical handoff.
Results are presented which are taken from a dual-mode handset testbed, from analytic models, and from simulations which characterize
the scalability of the proposed mechanism.
Mohammed Smadi received the B.Eng and Mgmt and M.A.Sc degrees in Computer Engineering from McMaster University in Hamilton, Ontario, Canada.
Mohammed received an NSERC doctoral award in 2005 and is currently a Ph.D. student at the Wireless Networking Group at McMaster
University.
Terence D. Todd received the B.A.Sc, M.A.Sc and Ph.D. degrees in Electrical Engineering from the University of Waterloo, Waterloo, Ontario,
Canada. While at Waterloo he spent 3 years as a Research Associate with the Computer Communications Networks Group (CCNG).
He is currently a Professor of Electrical and Computer Engineering at McMaster University in Hamilton, Ontario, Canada.
Professor Todd spent 1991 on research leave in the Distributed Systems Research Department at AT&T Bell Laboratories in Murray
Hill, NJ. He also spent 1998 on research leave at The Olivetti and Oracle Research Laboratory in Cambridge, England. While
at ORL he worked on the piconet project which was an early embedded wireless network testbed.
Dr. Todd’s research interests include metropolitan/local area networks, wireless communications and the performance analysis
of computer communication networks and systems. He is a past Editor of the IEEE/ACM Transactions on Networking and currently
holds the NSERC/RIM/CITO Chair on Pico-Cellular Wireless Internet Access Networks.
Dr. Todd is a Professional Engineer in the province of Ontario and a member of the IEEE.
Vytas Kezys was born in Hamilton, Canada in 1957. He received the B.Eng. degree in Electrical Engineering from McMaster University, Canada,
in 1979.
From 1979 to 1998, Mr. Kezys was involved in radar and communications research as Principal Research Engineer at the Communications
Research Laboratory, McMaster University. While at McMaster, his research activities included array signal processing for
low-angle tracking radar, radar signal processing, and smart antennas for wireless communications. Mr. Kezys was founder and
President of TalariCom Inc., a start-up company that developed cost effective smart antenna technologies for broadband wireless
access applications.
Currently, Mr. Kezys is Director of Advanced Products at Research in Motion in Waterloo, Canada.
Vahid S. Azhari received his B.S. and M.S. from the Department of Electrical and Computer Engineering, IUST and University of Tehran, Iran,
in 2000 and 2003 respectively. His M.S. research focused on designing scheduling algorithms for switch fabrics. He also worked
for two years for the Iranian Telecommunication Research Centre on developing software for SDH switches. He is currently pursuing
his Ph.D. degree at the Wireless Networking Laboratory, McMaster University, Canada. His main area of research includes handoff
management in integrated wireless networks, WLAN deployment techniques, and wireless mesh networks.
Dongmei Zhao received the Ph.D. degree in Electrical and Computer Engineering from the University of Waterloo, Waterloo, Ontario, Canada
in June 2002. Since July 2002 she has been with the Department of Electrical and Computer Engineering, McMaster University,
Hamilton, Ontario, Canada where she is an assistant professor. Dr. Zhao’s research interests include modeling and performance
analysis, quality-of-service provisioning, access control and admission control in wireless cellular networks and integrated
cellular and ad hoc networks. Dr. Zhao is a member of the IEEE. 相似文献
108.
Kelly SD Kemner KM Carley J Criddle C Jardine PM Marsh TL Phillips D Watson D Wu WM 《Environmental science & technology》2008,42(5):1558-1564
The success of sequestration-based remediation strategies will depend on detailed information, including the predominant U species present as sources before biostimulation and the products produced during and after in situ biostimulation. We used X-ray absorption spectroscopy to determine the valence state and chemical speciation of U in sediment samples collected at a variety of depths through the contaminant plume at the Field Research Center at Oak Ridge, TN, before and after approximately 400 days of in situ biostimulation, as well as in duplicate bioreduced sediments after 363 days of resting conditions. The results indicate that U(VI) in subsurface sediments was partially reduced to 10-40% U(IV) during biostimulation. After biostimulation, U was no longer bound to carbon ligands and was adsorbed to Fe/Mn minerals. Reduction of U(VI) to U(IV) continued in sediment samples stored under anaerobic condition at < 4 degrees C for 12 months, with the fraction of U(IV) in sediments more than doubling and U concentrations in the aqueous phase decreasing from 0.5-0.74 to < 0.1 microM. A shift of uranyl species from uranyl bound to phosphorus ligands to uranyl bound to carbon ligands and the formation of nanoparticulate uraninite occurred in the sediment samples during storage. 相似文献
109.
110.