Results 61 to 70 of about 734,125 (345)
Photonics, 2018 Ultra-long span unrepeatered systems using distributed Raman amplification are cost-effective solutions for bridging moderate transmission distances. However, there are two major limiting factors: nonlinear Kerr effect-induced nonlinear signal distortion
Ibrahim Syuaib +2 more
doaj +1 more source
A deep survey of heavy element lines in planetary nebulae - I. Observations and forbidden-line densities, temperatures and abundances [PDF]
Mon.Not.Roy.Astron.Soc. 345 (2003) 186, 2003 We present spectrophotometry of 12 Galactic and 3 Magellanic Cloud planetary nebulae (PNe). Nine of the Galactic PNe were observed by scanning the slit across the PN. We use the fluxes of collisionally excited lines (CELs) to derive electron densities (D's) and temperatures (T's), and ionic abundances.
arxiv +1 more source
Frequency-resolved noise figure measurements of phase (in)sensitive fiber optical parametric amplifiers [PDF]
, 2014 We measure the frequency-resolved noise figure of fiber optical parametric amplifiers both in phase-insensitive and phase-sensitive modes in the frequency range from 0.03 to 3 GHz.
Andrekson, Peter +4 more
core +1 more source
Journal of Applied Clinical Medical Physics, EarlyView.Abstract Purpose This study aims to evaluate how different gantry angles, breathing rates (BPM), cine image speeds, and tracking algorithms affect beam on/off latency and the subsequent impact on target dose for a 0.35T MR‐Linac with a 6 MV FFF beam.
Mateb Al Khalifa +4 more
wiley +1 more source
VLA Observations of the Gravitational Lens System Q2237+0305 [PDF]
, 1996 We report observations of the four-image gravitational lens system Q2237+0305 with the VLA at 20 cm and 3.6 cm. The quasar was detected at both frequencies (\approx 0.7 mJy) with a flat spectrum. All four lensed images are clearly resolved at 3.6 cm, and the agreement of the radio and optical image positions is excellent.
arxiv +1 more source
, 1997 We compare the performance of dispersion-shifted-fibre (DSF) and semiconductor-optical-amplifier (SOA) based phase conjugators for a 10 Gb/s non-return-to-zero system with respect to conversion efficiency, noise figure and distortion.
Cole, M.J. +4 more
core +1 more source
Journal of Applied Clinical Medical Physics, EarlyView.Abstract Purpose This study aims to develop a CycleGAN based denoising model to enhance the quality of low‐dose PET (LDPET) images, making them as close as possible to standard‐dose PET (SDPET) images. Methods Using a Philips Vereos PET/CT system, whole‐body PET images of fluorine‐18 fluorodeoxyglucose (18F‐FDG) were acquired from 37 patients to ...
Yang Liu, ZhiWu Sun, HaoJia Liu
wiley +1 more source
A Joint OSNR and Nonlinear Distortions Estimation Method for Optical Fiber Transmission System
IEEE Photonics Journal, 2018 In this paper, we propose and demonstrate a joint optical signal-to-noise ratio (OSNR) and a nonlinear distortions estimation method. The OSNR is calculated by considering either the link parameters or the correlation operations of the training symbols ...
Yating Xiang +6 more
doaj +1 more source
Why X-ray--Selected AGN Appear Optically Dull [PDF]
Astrophys.J.645:115-133,2006, 2006 We investigate why half of X-ray--selected active galactic nuclei (AGN) in deep surveys lack signs of accretion in their optical spectra. The majority of these ``optically--dull'' AGN are no more than 6 times fainter than their host galaxies in rest-frame R-band; as such, AGN lines are unlikely to be overwhelmed by stellar continuum in at least half ...
arxiv +1 more source
Two-photon-absorption-based OSNR monitor for NRZ-PSK transmission systems [PDF]
, 2010 A two-photon absorption microcavity-based technique for monitoring in-band optical signal-to-noise ratio (OSNR) in nonreturn-to-zero phase-shift-keying systems is presented.
Anandarajah, Prince M. +10 more
core +1 more source