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Pulse Repetition Frequency (pulse + repetition_frequency)
Selected AbstractsMelatonin modulates the action of near infrared radiation on cell adhesionJOURNAL OF PINEAL RESEARCH, Issue 3 2003Tiina I. Karu Abstract: The adhesion of human cervical cancer (HeLa) cells to a glass matrix is evaluated following their irradiation in a suspension with a pulsed near-infrared (IR) light-emitting diode (wavelength 820 nm, pulse repetition frequency 10 Hz, irradiation dose 16,120 J/m2) when melatonin (4 × 10,11 to 4 × 10,5 m) is added to cell suspension immediately before or after the irradiation. Also, the dependence of visible-to-near-IR radiation (600,840 nm, 52 J/m2) on cell adhesion (action spectrum) is recorded in absence and presence of melatonin (4 × 10,6 m). It is found that melatonin in pharmacological concentrations (but not in physiological range) inhibited cell adherence. Irradiation of cells before or after melatonin treatment normalizes cell adhesion to control level. Melatonin in pharmacological concentrations eliminates stimulation of cell attachment induced by irradiation. Pre-treatment (but not post-treatment) with melatonin in the physiological concentration eliminates cell adhesion stimulation induced by irradiation. Melatonin modifies the light action spectrum significantly in near IR region (760,840 nm only). Thus, the peak at 820,830 nm characteristic for the light action spectrum is fully reduced. [source] Continuous wave and passively Q-switched laser performance of the mixed crystal Nd:Lu0.15Y0.85VO4LASER PHYSICS LETTERS, Issue 5 2010S. Zhang Abstract Laser characteristics of a novel mixed laser crystal Nd:Lu0.15Y0.85VO4 was investigated. It is attractive for Q-switching with high repetition rate and short pulse width due to its suitable stimulated emission cross-section and short upper level lifetime. Continuous wave (CW) output power of 8.18 W was obtained at the pump power of 18.9 W, corresponding to the optical conversion efficiency of 43.3% and the slope efficiency of 47%. In the passive Q-switching operation, the minimum pulse width attained was 7.8 ns, with the pulse repetition frequency of 23.2 kHz, with the single pulse energy and peak power estimated to be 94.8 ,J and 12.2 kW, respectively. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] A CMOS differential fifth-derivative Gaussian pulse generator for UWB applicationsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 8 2010Jin He Abstract A CMOS differential fifth-derivative Gaussian pulse generator is presented for Ultrawideband (UWB) applications. The design exhibits low-power consumption, low-circuit complexity, and precise pulse shape to inherently comply with the FCC spectrum mask for indoor UWB applications without the need for a filter. The proposed differential pulse generator was implemented with a 1.8-V, 0.18-,m CMOS process, but only the positive fifth-derivative Gaussian pulse was measured owing to the limitation of the available testing facilities. The measured pulse has peak-to-peak amplitude of 154 mV and a pulse width of 820 ps. Small core area of the differential pulse generator is only 0.028 mm2 because of its all digital circuit design. The average power dissipation is 1.2 mW with a pulse repetition frequency (PRF) of 50 MHz. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1849,1852, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25342 [source] Absence of corneal endothelium injury in non-human primates treated with and without ophthalmologic drugs and exposed to 2.8,GHz pulsed microwaves,,BIOELECTROMAGNETICS, Issue 4 2010Shin-Tsu Lu Abstract Microwave-induced corneal endothelial damage was reported to have a low threshold (2.6,W/kg), and vasoactive ophthalmologic medications lowered the threshold by a factor of 10,0.26,W/kg. In an attempt to confirm these observations, four adult male Rhesus monkeys (Macaca mulatta) under propofol anesthesia were exposed to pulsed microwaves in the far field of a 2.8,GHz signal (1.43,±,0.06,µs pulse width, 34,Hz pulse repetition frequency, 13.0,mW/cm2 spatial and temporal average, and 464,W/cm2 spatial and temporal peak (291,W/cm2 square wave equivalent) power densities). Corneal-specific absorption rate was 5.07,W/kg (0.39,W/kg/mW/cm2). The exposure resulted in a 1.0,1.2,°C increase in eyelid temperature. In Experiment I, exposures were 4,h/day, 3 days/week for 3 weeks (nine exposures and 36,h total). In Experiment II, these subjects were pretreated with 0.5% Timolol maleate and 0.005% Xalatan® followed by 3 or 7 4-h pulsed microwave exposures. Under ketamine,xylazine anesthesia, a non-contact specular microscope was used to obtain corneal endothelium images, corneal endothelial cell density, and pachymetry at the center and four peripheral areas of the cornea. Ophthalmologic measurements were done before and 7, 30, 90, and 180 days after exposures. Pulsed microwave exposure did not cause alterations in corneal endothelial cell density and corneal thickness with or without ophthalmologic drugs. Therefore, previously reported changes in the cornea exposed to pulsed microwaves were not confirmed at exposure levels that are more than an order of magnitude higher. Bioelectromagnetics 31:324,333, 2010. Published 2010 Wiley-Liss, Inc. [source] | ||||||||||