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排序方式: 共有313条查询结果,搜索用时 15 毫秒
41.
Kim I. Alferness R.C. Buhl L.L. Koren U. Miller B.I. Young M.G. Newkirk M.A. Chien M.D. Koch T.L. Raybon G. Burrus C.A. 《Photonics Technology Letters, IEEE》1993,5(11):1319-1321
A photonic integrated circuit with an InGaAs/InGaAsP multiple-quantum-well (MQW) traveling-wave optical amplifier and a grating-assisted vertical-coupler filter as a noise filter have been demonstrated. A fiber-to-amplifier/filter gain of ~0.5 dB and a 3-dB filter bandwidth (FWHM) of ~70 Å at 1.56 μm filter center wavelength have been achieved. This photonic circuit is potentially suitable as a building-block for preamplifier lightwave receivers or high-gain, high-power optical amplifiers which are essential for optical communication systems and lightwave networks 相似文献
42.
Characterization of a slowly inactivating outward current in adult mouse ventricular myocytes 总被引:1,自引:0,他引:1
We recently have reported that suppression of the slowly inactivating component of the outward current, Islow, in ventricular myocytes of transgenic mice (long QT mice) overexpressing the N-terminal fragment and S1 segment of Kv1.1 resulted in a significant prolongation of action potential duration and the QT interval. Here we describe the detailed biophysical properties and physiological role of Islow by applying the whole-cell patch-clamp technique at both room temperature and 37 degreesC. This current activates rapidly with time constants ranging from 3.8+/-0.8 ms at -20 mV to 2.1+/-0.5 ms at 50 mV at room temperature. The half-activation voltage and slope factor are -12.5+/-2.6 mV and 7. 7+/-1.0 mV, respectively. The inactivation of this current is slow compared with the fast inactivating component Ito, with time constants of approximately 100 ms at 37 degreesC. The steady-state inactivation of Islow is not temperature-dependent, with half-inactivation voltages and slope factors of -35.1+/-1.3 and -5. 4+/-0.4 mV at 37 degreesC, and -37.6+/-1.8 and -5.8+/-0.6 mV at room temperature. Double exponentials were required to describe the time-dependent recovery of Islow from steady-state inactivation, with time constants of 233+/-34 and 3730+/-702 ms at 37 degreesC, and 830+/-240 and 8680+/-2410 ms at room temperature. Islow is highly sensitive to 4-aminopyridine but is insensitive to tetraethylammonium, alpha-dendrotoxin, and E-4031. Stimulation with action-potential waveforms under voltage-clamp mode revealed that this current plays an important role in the early and middle phases of repolarization of the cardiac action potential. We conclude that the biophysical properties and pharmacological profiles of Islow are similar to those of Kv1.5-encoded currents. 相似文献
43.
R Koren S Kyzer A Paz V Veltman B Klein R Gal 《Canadian Metallurgical Quarterly》1997,21(11):1387-1390
The staging and prognosis of patients with breast cancer is related to the presence or absence of axillary lymph node involvement. However, in some cases no lymph nodes or too small a number of lymph nodes are revealed by the traditional method of palpating and sectioning the axillary fat. In the present study we demonstrate the usefulness of the lymph node revealing solution (LNRS) in breast cancer. Specimens from 13 patients, in whom <10 lymph nodes were identified in the axilla by the traditional method, were included in the study. After excising the lymph nodes by the traditional method, axillary tissue was immersed in LNRS for 6-12 hours. Additional lymph nodes, which stood out as white chalky nodules, were excised and processed as usual. The LNRS increased the mean number of nodes per case from 6.0+/-2.5 found by the traditional method to 12.54+/-4.61 nodes per case (p < 0.01). The size of the nodes identified by the LNRS was significantly smaller (p < 0.01) than those detected by the traditional method. The LNRS changed the lymph node stage of the disease in four of the studied cases (30%). LNRS seems to be the technique of choice for detection of axillary lymph nodes in cases where the number of detected lymph nodes by the traditional method is too small for accurate staging. 相似文献
44.
JG Theis M Liau-Chu HS Chan J Doyle ML Greenberg G Koren 《Canadian Metallurgical Quarterly》1995,13(10):2508-2516
PURPOSE: An unusually high incidence of anaphylactoid reactions was observed during a phase I/II trial of high-dose intravenous cyclosporine (CsA) therapy to attenuate tumor multidrug resistance (MDR). Five of 21 children experienced severe anaphylactoid reactions shortly after initiation of the first or second CsA infusion. We hypothesized that improper dissolution of the vehicle Cremophor EL may have been a cause for these anaphylactoid reactions. METHODS: All nurses who had administered intravenous CsA were interviewed regarding their technique of preparing the infusion and the occurrence of an anaphylactoid reaction. The responses were statistically analyzed. The effect of various mixing techniques on the distribution of Cremophor EL in the infusion was experimentally evaluated. Different mixing techniques were used to assess their effect on the distribution of Cremophor EL in the solution. RESULTS: Analysis of the preparation techniques of the CsA infusion showed significant correlation between suboptimal mixing of CsA by nurses and the occurrence of anaphylactoid reactions (P = .02). Experimental simulation showed that suboptimal mixing results in an uneven distribution of Cremophor EL, which subsequently sinks to the bottom of the vial. CONCLUSION: Improper mixing of high-dose CsA infusions causes nonsolubilized Cremophor EL to sink to the outflow area of the bottle. An initial bolus infusion of highly concentrated Cremophor EL may produce an anaphylactoid-like response. This mechanism of toxicity is important to recognize, because it is easily preventable by proper preparation of the infusion, thus reducing the incidence of potentially life-threatening anaphylactoid reactions. 相似文献
45.
Z Koren H Schulman M Lev-Gur M Gatz B Thysen E Bloch 《Canadian Metallurgical Quarterly》1976,48(4):427-424
Progesterone concentrations in amniotic fluid and maternal plasma were determined in 11 midtrimester pregnant patients following the intraamniotic administration of prostaglandin F2alpha. Samples were obtained at 3-hour intervals until abortion or spontaneous rupture of membranes occurred or fetal heart tones disappeared. In amniotic fluid, the mean progesterone concentrations increased throughout the sampling period. The plasma progesterone levels declined by about one-third of basal values in the first 3 hours after prostaglandin administration. The paradoxic increase in amniotic fluid progesterone is probably secondary to alterations in uterine blood flow and intrauterine pressure. 相似文献
46.
Zirngibl M. Joyner C.H. Stulz L.W. Koren U. Chien M.-D. Young M.G. Miller B.I. 《Photonics Technology Letters, IEEE》1994,6(4):516-518
A novel monolithic semiconductor laser is demonstrated. The optical cavity comprises a 1×N waveguide grating multiplexer connected to N optical amplifiers. By driving a specific output port, laser oscillation is obtained at the wavelength determined by the wavelength path through the multiplexer. Such a laser is very useful for WDM systems because it is capable of producing a comb of precisely spaced frequencies 相似文献
47.
Koren U. Miller B.I. Eisenstein G. Tucker R.S. Raybon G. Capile R.J. 《Electronics letters》1988,24(3):138-140
A high-power, high-speed GaInAsP/InP laser operating at a 1.3-μm wavelength is described. The laser is obtained with three epitaxial growth steps and has semi-insulating InP blocking layers resulting in low parasitic capacitance. A 3 dB bandwidth of 14.7 GHz together with 38 mW output power has been achieved 相似文献
48.
Shoval S. Borenstein J. Koren Y. 《IEEE transactions on systems, man and cybernetics. Part C, Applications and reviews》1998,28(3):459-467
A blind traveler walking through an unfamiliar environment and a mobile robot navigating through a cluttered environment have an important feature in common: both have the kinematic ability to perform the motion, but they are dependent on a sensory system to detect and avoid obstacles. The paper describes the use of a mobile robot obstacle avoidance system as a guidance device for blind and visually impaired people. Just as electronic signals are sent to a mobile robot's motion controllers, auditory signals can guide the blind traveler around obstacles, or alternatively, they can provide an “acoustic image” of the surroundings. The concept has been implemented and tested in a new travel aid for the blind, called the Navbelt. The Navbelt introduces two new concepts to electronic travel aids (ETA's) for the blind: it provides information not only about obstacles along the traveled path, but also assists the user in selecting the preferred travel path. In addition, the level of assistance can be automatically adjusted according to changes in the environment and the user's needs and capabilities. Experimental results conducted with the Navbelt simulator and a portable experimental prototype are presented 相似文献
49.
S Ito S Weitzman J Klein M Greenberg R Lau G Atanakovic G Koren 《Canadian Metallurgical Quarterly》1998,62(25):PL387-PL392
The interactions between cisplatin and organic ions have been extensively investigated in animal models for the potential to reduce cisplatin cellular uptake and resultant nephrotoxicity. To further investigate the beneficial interaction clinically, we studied the effects of the organic cation, ranitidine, on the renal handling of cisplatin in children. In parallel, we examined the effects of cisplatin on the uptake kinetics of organic cations and anions by brush border membrane vesicles (BBMV) prepared from dog renal cortex. The results indicate that: 1) there is no measurable effect of ranitidine on renal clearance of cisplatin in children; and 2) BBMV uptake of anionic p-aminohippurate, but not cationic N-methylnicotinamide, is inhibited by cisplatin at concentrations of <1 mM. These findings suggest that cisplatin may not share transport systems with organic cations to a clinically significant degree. Assuming that renal tubular transport is a prerequisite for cisplatin nephrotoxicity, the lack of apparent kinetic interactions between cisplatin and organic cations may preclude clinical use of organic cations as a modality to prevent cisplatin nephrotoxicity. 相似文献
50.
Y Ye FA Neethling M Niekrasz E Koren SV Richards M Martin S Kosanke R Oriol DK Cooper 《Canadian Metallurgical Quarterly》1994,58(3):330-337
Methods of inhibiting the hyperacute antibody-mediated rejection that occurs when pig organs are transplanted into primates have been investigated using the baboon as a potential recipient. Baboons were treated with different regimens that included combinations of (1) splenectomy, (2) pharmacologic immunosuppression (CsA, cyclophosphamide, corticosteroids +/- methotrexate), and (3) intravenous infusion of oligosaccharides. The cytotoxicity of the serum was then assessed on cultures of pig kidney cells (PK15). Unmodified serum caused approximate 65-100% pig cell destruction. Splenectomy and/or pharmacologic immunosuppression, and infusions of dextran, dextrose or mannitol, did not result in any reduction of cytotoxicity. Infusions of melibiose and/or arabinogalactan, both of which have terminal non-reducing alpha-galactose, however, decreased relative PK15 cell damage significantly in a dose-dependent manner. At high concentrations (< or = 50 g/hr), complete inhibition of cytotoxicity was achieved in 4 of 15 baboons. The extracorporeal immunoadsorption of baboon serum utilizing immunoaffinity columns of melibiose also resulted in a significant reduction (of approximately 80%) in cytotoxic effect. In 1 baboon, melibiose and arabinogalactan infusion delayed vascular rejection of a pig cardiac xenograft from 10 min to about 12 hr, at which time the baboon died from the toxic effects of the carbohydrate infusion. These observations (1) add further support to the role that anti-alpha-galactosyl antibodies play in the hyperacute rejection of pig tissues transplanted into primates, and (2) demonstrate that serum cytotoxicity can be reduced by the intravenous infusion of alpha-galactosyl oligosaccharides or by extracorporeal immunoadsorption using these carbohydrates. 相似文献