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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 2480-2482 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: By using growth striation technique, an acoustic superlattice of barium sodium niobate crystals, the single crystals with the periodic laminar ferroelectric domain structures, has been prepared. High-frequency resonance in the range of 200–400 MHz in such materials has been realized experimentally. The experimental results indicate that the application of acoustic devices with low acoustic loss operating at high frequencies is expected.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1542-474X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: We conducted a study of chronic therapy with flecainide versus placebo in a small group of LQT-3 patients with the ΔKPQ deletion to evaluate the safety and efficacy of flecainide in this genetic disorder. In vitro studies have shown that flecainide provides correction of the impaired inactivation associated with the ΔKPQ deletion. Methods: A randomized, double-blind, placebo-controlled clinical trial was conducted with flecainide and placebo in six male LQT-3 subjects with the ΔKPQ deletion. Results: The lowest possible dose of flecainide associated with at least a 40 ms reduction in the QTc interval was determined in an initial open-label, dose-ranging investigation using one-fourth or half of the recommended maximal antiarrhythmic flecainide dose. QTc reduction was achieved with a flecainide dose of 1.5 mg/kg per day in 4 subjects and with 3.0 mg/kg per day in 2 subjects. Subjects were randomized to four 6-month alternating periods of flecainide and placebo therapy based on the open-label dose findings. Average QTc values during placebo and flecainide therapies were 534 ms and 503 ms, respectively, with an adjusted reduction in QTc of −27.1 ms (95% confidence interval: −36.8 ms to −17.4 ms; P 〈 0.001) at a mean flecainide blood level of 0.11 ±0.05 μg/ml. Minimal prolongation in QRS occurred (mean: +2.5 ms), and there were no major adverse cardiac effects. Conclusions: Chronic low-dose flecainide significantly shortens the QTc interval in LQT-3 subjects with the ΔKPQ mutation. No major adverse drug effects were observed with flecainide during this trial, but the sample size is not large enough to evaluate the safety of flecainide therapy in patients with this mutation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 14 (2003), S. 0 
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Recent data showed that long QT syndrome (LQTS) patients with mutations in the pore region of the HERG (LQT2) gene have significantly higher risk of cardiac events than subjects with mutations in the non-pore region. The aim of this study was to determine whether there is an association between the location of mutations in the KCNQ1 gene and cardiac events in LQT1 patients. Methods and Results: The study population consisted of 294 LQT1 patients with KCNQ1 gene mutations. Demographic, clinical, and follow-up information was compared among subjects with different locations of KCNQ1 mutations defined as pre-pore region including N-terminus (1–278), pore region (279–354), and post-pore region including C-terminus (〉354). Cardiac events observed during follow-up from birth until age of last contact or age 40 years were defined as syncope, cardiac arrest, or sudden death. There were 164 (56%) LQT1 patients with pre-pore mutations, 101 (34%) with pore mutations, and 29 (10%) with post-pore mutations. QTc duration did not differ significantly among the three subgroups (mean QTc = 494, 487, and 501 ms, respectively). There was no significant difference between groups with regard to the risk of cardiac events by age 40 years. Conclusion: There are no significant differences in clinical presentation, ECG parameters, and cardiac events among LQT1 patients with different locations of KCNQ1 mutations. These findings indicate that factors other than location of mutation influence clinical phenotype in patients with LQT1 mutations. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1149-1153, November 2003)
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    350 Main Street , Malden , MA 02148 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Annals of noninvasive electrocardiology 8 (2003), S. 0 
    ISSN: 1542-474X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: The Jervell and Lange-Nielsen syndrome (JLNS) is the autosomal recessive form of long QT syndrome (LQTS)—a familial cardiac disorder that causes syncope, seizures, and sudden death from ventricular arrhythmias, specifically torsade de pointes. JLNS is associated with sensorineural deafness and has been shown to occur with homozygous mutations in KCNQ1 or KCNE1 in JLNS families in which QTc prolongation is inherited as a dominant trait. This study investigated the molecular pathology of a family with clinical evidence of JLNS. Methods and Results: Single-strand conformation polymorphism, denaturing high performance liquid chromatography, and DNA sequencing analyses were used to screen for KCNQ1 mutations. Novel compound heterozygous nonsense mutations R518X/Q530X in the C-terminus of KCNQ1 were identified in both affected dizygotic twins; both the parents and a sibling each carried only one of the mutant alleles and were asymptomatic with modestly prolonged QTc intervals (0.46, 0.50, and 0.45 seconds, respectively). These two nonsense mutations lead to premature termination of C-terminus with truncation of the postulated assembly domain. Conclusion: Novel compound heterozygous nonsense mutations in C-terminus of KCNQ1 can cause JLNS.               A.N.E 2003;8(3):246-250
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 111-116 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The screw dislocations with Burgers vector a〈001〉 and a〈110〉 in Ba(NO3)2 crystals have been studied by birefringence topography. In combination with the results obtained previously [C.-Z. Ge, N.-B. Ming, K. Tsukamoto, K. Maiwa, and I. Sunagawa, J. Appl. Phys. 69, 7556 (1991); C.-Z. Ge, H.-W. Wang, and N.-B. Ming, ibid. 74, 139 (1993)], it has been shown that not only a〈111〉, but also a〈110〉 screw dislocations viewed end-on are visible; however, a〈100〉 screw dislocation viewed end-on are always invisible in barium nitrate crystals. The intensity distributions and extinction rules of birefringence images of a〈110〉 screw dislocation viewed end-on are determined both experimentally and theoretically. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 7265-7268 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Raman scattering by longitudinal-optical (LO) phonon-plasmon-coupled (LOPC) mode in carbon-doped p-type InGaAs with indium composition x≈0.3 and hole concentration from 1017 to 1019 cm−3 grown by metalorganic molecular beam epitaxy was studied experimentally. Only one LOPC mode appears between the GaAs-like and InAs-like LO modes was observed. The peak position of the LOPC mode is near the GaAs-like transverse-optical mode frequency and is insensitive to the hole concentration. The linewidth and intensity of the LOPC mode are dependent strongly on the carrier concentration, while the two LO modes decrease and become invisible under the high doping level. It was shown that the plasmon damping effect plays a dominant role in Raman scattering by LOPC mode for the p-type InGaAs. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 3511-3513 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Semiconductor microlasers with an equilateral triangle resonator (ETR) and an output waveguide are proposed and analyzed by the finite-difference time-domain technique and the Padé approximation. The numerical results show that microlasers with an output waveguide still have a high-quality factor (Q factor) and are suitable to realize directional emission. For the ETR with a 0.46-μm-width opening in one of the vertices connected to the output waveguide, we have the Q factor of 1.5×103 and 2.5×102 for the TM fundamental mode at the wavelength of 1.55 μm, as the side length of the ETR is 5 and 3 μm. The simulated intensity distributions are presented for the fundamental mode in the ETR with a side length of 3 μm and an opening of 0.23 μm. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1572-9443
    Keywords: queueing theory ; matrix analytic methods ; tree structure ; LCFS ; quasi-birth-and-death Markov process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper studies two queueing systems with a Markov arrival process with marked arrivals and PH-distribution service times for each type of customer. Customers (regardless of their types) are served on a last-come-first-served preemptive resume and repeat basis, respectively. The focus is on the stationary distribution of queue strings in the system and busy periods. Efficient algorithms are developed for computing the stationary distribution of queue strings, the mean numbers of customers served in a busy period, and the mean length of a busy period. Comparison is conducted numerically between performance measures of queueing systems with preemptive resume and preemptive repeat service disciplines. A counter-intuitive observation is that for a class of service time distributions, the repeat discipline performs better than the resume one.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Queueing systems 35 (2000), S. 323-347 
    ISSN: 1572-9443
    Keywords: retrial queue ; ergodicity ; sample path method ; mean-drift method ; matrix analytic methods ; batch Markov arrival process (BMAP) ; PH-distribution ; impatient customer ; Lyapunov function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Define the traffic intensity as the ratio of the arrival rate to the service rate. This paper shows that the BMAP/PH/s/s+K retrial queue with PH-retrial times is ergodic if and only if its traffic intensity is less than one. The result implies that the BMAP/PH/s/s+K retrial queue with PH-retrial times and the corresponding BMAP/PH/s queue have the same condition for ergodicity, a fact which has been believed for a long time without rigorous proof. This paper also shows that the same condition is necessary and sufficient for two modified retrial queueing systems to be ergodic. In addition, conditions for ergodicity of two BMAP/PH/s/s+K retrial queues with PH-retrial times and impatient customers are obtained.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 475-479 (Jan. 2005), p. 2635-2638 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Milisecond high density electrical pulse was used to age one of the typical IC lead frame materials Cu-2.5Fe-0.03P-0.1Zn copper alloy. The effects of electrical pulse aging on the microstructures, electrical conductivity and microhardness of this alloy were systematically investigated. The experimental results shown that the alloy phase precipitated in Cu-2.5Fe-0.03P-0.1Zn copper alloy during electrical pulse aging could be controlled to the order of nano-size and the ideal match of electrical conductivity and microhardness could be achieved in the condition of optimized parameters of electrical pulse. The electrical conductivity of the alloy was kept at above 60%IACS while the microhardness reached to HV115. A preliminary theoretical analysis was made to explain the unique action of electrical pulse
    Type of Medium: Electronic Resource
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