排序方式: 共有17条查询结果,搜索用时 15 毫秒
1.
A. Coppa V. Foglietti E. Giovine A. Doria G.P. Gallerano E. Giovenale A. Cetronio C. Lanzieri M. Peroni F. Evangelisti 《Infrared Physics & Technology》2008,51(5):470-472
An active two dimensional near field imaging of a High Electron Mobility Transistor (HEMT) used as THz detector has been performed. The reflective imaging system developed at the ENEA FEL Facility in Frascati has been used to this purpose. This imaging technique has shown to be particularly powerful in resolving various coupling mechanisms of the incident radiation with the device. 相似文献
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E. Amaldi E. Coccia C. Cosmelli Y. Ogawa G. Pizzella P. Rapagnani F. Ricci P. Bonifazi M. G. Castellano G. Vannaroni F. Bronzini P. Carelli V. Foglietti G. Cavallari R. Habel I. Modena G. V. Pallottino 《Il Nuovo Cimento C》1984,7(3):338-354
Summary We report on the cooling at liquid-helium temperature of our 2270 kg 5056 Al bar at CERN. The liquid-helium container had
been filled up to 1500 liters ensuring to keep the antenna cold for more than one month. The antenna is equipped with a resonant
capacitive transducer operating at constant electrical charge with a FET low-noise amplifier. The transducer is tuned to the
antenna within less than I Hz and the two normal-mode frequencies are ν−=908.160 Hz and ν+=924.234 Hz with an applied electrical field in the transducer of 106 V/m. The corresponding overall merit factors areQ
−=5.20·106 andQ
+=7.25·106. The transducer has been tested up to an electrical field of 6·106 V/m: in this condition we have βQ≈104. The antenna has been in operation for several weeks giving, for the Brownian noise, values in agreement with the calculated
values. We report also on the results of tests performed on a DC SQUID, whose input was connected to a commercial capacitor
via a transformer with turn ratio of 1000.
Supported in part by Japan Society for the Promotion of Science. 相似文献
3.
Fluorogenic Probes Applied to the Study of Induced Oxidative Stress in the Human Leukemic HL60 Cell Line 总被引:1,自引:0,他引:1
E. Plantin-Carrenard F. Braut-Boucher M. Bernard C. Derappe M. J. Foglietti M. Aubery 《Journal of fluorescence》2000,10(2):167-167
Development of microspectrofluorometric methods using specific fluorogenic probes has provided precious help in studying in situ oxidative stress and cellular protective systems. The aim of this study was to determine ROS production concomitantly with a modification of the intracellular thiol pool after applying an oxidative stress to a nonadherent cell model represented by the HL60 cell line. The dichlorodihydrofluorescein diacetate (H2DCFDA) probe assessed the kinetic production of ROS by cells submitted to the chemical oxidant t-butylhydroperoxide with a high signal/noise ratio. The probe sensitivity permitted us to detect endogenous ROS production in HL60 cells and the protective effect of N-acetyl cysteine against ROS. The chloromethylfluorescein diacetate probe (CMFDA) permitted us to evaluate the thiol depleting effect of N-ethyl maleimide. Complete thiol depletion was associated with a moderate increase in ROS production. The cell viability was determined with calcein-AM, which gave results similar to those with the tetrazolium dye. This probe was not affected by intracellular pH and did not required an extraction step, unlike tetrazolium dye. In conclusion, cell-permeant fluorogenic probes are useful and sensitive tools to determine in situ ROS production concomitantly with consecutive change in the thiol system in a living and non-adherent cell model. 相似文献
4.
Longhi S Marangoni M Lobino M Ramponi R Laporta P Cianci E Foglietti V 《Physical review letters》2006,96(24):243901
We report on a direct experimental observation of dynamic localization (DL) of light in sinusoidally-curved lithium-niobate waveguide arrays which provides the optical analog of DL for electrons in periodic potentials subjected to ac electric fields as originally proposed by Dunlap and Kenkre [Phys. Rev. B 34, 3625 (1986)10.1103/PhysRevB.34.3625]. The theoretical condition for DL in a sinusoidal field is experimentally demonstrated. 相似文献
5.
A. Chiasera C. Armellini S.N.B. Bhaktha A. Chiappini Y. Jestin M. Ferrari E. Moser A. Coppa V. Foglietti P.T. Huy K. Tran Ngoc G. Nunzi Conti S. Pelli G.C. Righini G. Speranza 《Journal of Non》2009,355(18-21):1176-1179
95.8SiO2–4.2HfO2 planar waveguide activated by 0.2 mol% Er and 0.2 mol% Yb was fabricated by multi-target rf-sputtering technique. The optical parameters were measured by an m-line apparatus operating at 543.5, 632.8, 1319 and 1542 nm. The waveguide compositions were investigated by energy dispersive spectroscopy. The waveguide exhibits a single propagation mode at 1.3 and 1.5 μm with an attenuation coefficient of 0.2 dB/cm at 1.5 μm. The emission of 4I13/2 → 4I15/2 transition of Er3+ ion, with a 42 nm bandwidth was observed upon TE0 mode excitation at 980 and 514.5 nm. Photoluminescence excitation spectroscopy was used to obtain information about the effective excitation efficiency of Er3+ ions by co-doping with Yb3+ ions. Channel waveguide in rib configuration were fabricated by wet etching process in the active film. 相似文献
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Longhi S Marangoni M Janner D Ramponi R Laporta P Cianci E Foglietti V 《Physical review letters》2005,94(7):073002
We report on the first experimental observation of wave packet dichotomy and adiabatic stabilization of light in a periodically bent optical waveguide in analogy with similar behavior of atoms in high-frequency strong laser fields. 相似文献
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Summary An investigation of the spontaneous brain activity from normal subjects has been carried out by means of the neuromagnetic
method. Two different systems were used for magnetic measurements. Both used 2nd-order gradiometers specifically designed
for brain studies: 2.9 cm diameter, 5 cm baseline. A r.f. SQUID and a d.c. SQUID were coupled to the gradiometers. The measured
noise levels are
and
, respectively. Thorough magnetic mapping of the spontaneous activity was performed on a few subjects. By mapping the average
amplitude of the α-rhythm signals two maxima of activity over two symmetric regions of the scalp were clearly observed. Despite
a general symmetry between hemispheres, however, the complexity of the measured maps suggests a corresponding complexity of
the generators responsible for α-activity.
Partially supported by Progetto Finalizzato Superconduttività 相似文献