248 research outputs found
A 10-Meter Active Optical Cable Utilizing POF With 4 × 10-Gb/s CMOS Transceiver Chipsets
This paper presents a 10-m active optical cable (AOC) utilizing a graded-index plastic optical fiber (POF) for HDMI applications, where 4-channel 10-Gb/s/ch transceiver chipsets were implemented in 0.13-μm CMOS process and integrated upon a FR4 PC-board within pluggable connectors. Passive optical alignment comprising optical devices, optical subassembly, and POF was precisely located within the tolerance range of +/-10 μm, leading to successful mass-production. The transmitter (Tx) includes a VCSEL driver exploiting equalization and feedforward pre-emphasis to support 10-Gb/s data modulation. Also, a novel input data detector is proposed to turn on/off VCSEL diodes automatically for longer sustainability and lower power consumption. The receiver (Rx) employs a double-gain feedforward transimpedance amplifier followed by a selectable two-stage equalizer to choose either 6-Gb/s or 10-Gb/s operations, depending upon the specified HDMI applications. Also, a simple dc offset current cancellation and a novel monitor circuit are proposed for stable biasing and to keep tracking the average photocurrent of each photodiode. Measured results of Tx demonstrate 5.6-mA bias currents and 6.0-mAPP modulation currents, consuming 21.25 mA in maximum, whereas Rx provides 56.7-dBΩ transimpedance gain, 6-GHz bandwidth, and -10.4-dBm optical sensitivity for 10 -12 BER with 21.2 mA current consumption. The 10-meter POF AOC demonstrates wide and clean eye-diagrams up to 10 Gb/s, successfully showing 8-Mpixel 60-fps video data stream
Bilateral Carotid and Vertebral Rete Mirabile Presenting with a Prominent Anterior Spinal Artery Mimicking a Spinal Dural AV Fistula at MRI
Bilateral carotid and vertebral rete mirabile (CVRM) is a very rare condition. We report a new case of CVRM initially detected by magnetic resonance imaging (MRI) of the cervical spine. MRI demonstrated tortuous vascular signal voids limited to the anterior cerebrospinal fluid space mimicking spinal dural arteriovenous fistula. A diagnosis of CVRM was confirmed on the basis of angiographic findings of rete formation associated with bilateral aplasia of the cavernous internal carotid and vertebral arteries without abnormal arteriovenous connection
Kelvin-Helmholtz instabilities with Godunov SPH
Numerical simulations for the non-linear development of Kelvin-Helmholtz
instability in two different density layers have been performed with the
particle-based method (Godunov SPH) developed by Inutsuka (2002). The Godunov
SPH can describe the Kelvin-Helmholtz instability even with a high density
contrast, while the standard SPH shows the absence of the instability across a
density gradient (Agertz et al. 2007). The interaction of a dense blob with a
hot ambient medium has been performed also. The Godunov SPH describes the
formation and evolution of the fingers due to the combinations of
Rayleigh-Taylor, Richtmyer-Meshkov, and Kelvin-Helmholtz instabilities. The
blob test result coincides well with the results of the grid-based codes. An
inaccurate handling of a density gradient in the standard SPH has been pointed
out as the direct reason of the absence of the instabilities. An unphysical
force happens at the density gradient even in a pressure equilibrium, and
repulses particles from the initial density discontinuity. Therefore, the
initial perturbation damps, and a gap forms at the discontinuity. The
unphysical force has been studied in terms of the consistency of a numerical
scheme. Contrary to the standard SPH, the momentum equation of the Godunov SPH
doesnt use the particle approximation, and has been derived from the kernel
convolution or a new Lagrangian function. The new Lagrangian function used in
the Godunov SPH is more analogous to the real Lagrangian function for
continuum. The momentum equation of the Godunov SPH has much better linear
consistency, so the unphysical force is greatly reduced compared to the
standard SPH in a high density contrast.Comment: 11 pages, 7 figures, Accepted for publication in MNRA
An implicit method for radiative transfer with the diffusion approximation in SPH
An implicit method for radiative transfer in SPH is described. The diffusion
approximation is used, and the hydrodynamic calculations are performed by a
fully three--dimensional SPH code. Instead of the energy equation of state for
an ideal gas, various energy states and the dissociation of hydrogen molecules
are considered in the energy calculation for a more realistic temperature and
pressure determination. In order to test the implicit code, we have performed
non--isothermal collapse simulations of a centrally condensed cloud, and have
compared our results with those of finite difference calculations performed by
MB93. The results produced by the two completely different numerical methods
agree well with each other.Comment: 25 pages, 9 figure
Fatal Delayed Coronary Artery Perforation After Coronary Stent Implantation
Most type I and II perforations are predominately caused by hydrophilic and stiff wires, often presented in the delayed form, and do not require pericardial drainage or surgical interventions. However, we report a type III delayed coronary artery perforation at the site of stent implantation after intervention without any evidence of immediate perforations. To the best of our knowledge, this is the first case report of angiographic documentation and treatment of delayed coronary perforation at the site of stent, presented as a cardiac arrest
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