Dispersion compensation with SBS-suppressed fibre phase conjugator using synchronised phase modulation

204 km, 10 Gbit/s standard optical fibre transmission is successfully demonstrated using the mid-span spectral inversion technique with a stimulated Brillouin scattering suppressed fibre phase conjugator, proposed recently by Tani and Yamashita. Transmission performance has been improved compared with a conventional phase conjugator.     

Dirac Cone Spin Polarization of Graphene by Magnetic Insulator Proximity Effect Probed with Outermost Surface Spin Spectroscopy

The effects of the proximity contact with magnetic insulator on the spin‐dependent electronic structure of graphene are explored for the heterostructure of single‐layer graphene (SLG) and yttrium iron garnet Y₃Fe₅O₁₂ (YIG) by means of outermost surface spin spectroscopy using a spin‐polarized metastable He atom beam. In the SLG/YIG heterostructure, the Dirac cone electrons of graphene are found to be negatively spin polarized in parallel to the minority spins of YIG with a large polarization degree, without giving rise to significant changes in the π band structure. Theoretical calculations reveal the electrostatic interfacial interactions providing a strong physical adhesion and the indirect exchange interaction causing the spin polarization of SLG at the interface with YIG. The Hall device of the SLG/YIG heterostructure exhibits a nonlinear Hall resistance attributable to the anomalous Hall effect, implying the extrinsic spin–orbit interactions as another manifestation of the proximity effect.     

A Unified Approach to Submicron DC MOS Transistor Modeling for Low-Voltage ICs

A unified single-equation approach for the MOS transistordrain current modeling for energy-efficient submicron MOS circuitsis presented. Instead of three sets of separate equations forthe triode, saturation, and weak inversion regions, only a continuousexpression which is valid to describe the behavior of drain currentand the derivatives in all operation regions can be realizedby using a combination of hyperbola, sigmoid, and interpolationmethods. The model expression can predict accurate results forthe current, output conductance, and transconductance with continuousand smooth characteristics. The simulation results agree wellwith experimental data.     

Modal dispersion control and distortion suppression of picosecondpulses in suspended coplanar waveguides

The propagation and dispersion characteristics of picosecond electrical pulses in a suspended coplanar waveguide (SCPW) are investigated, and it is shown that the SCPW is a very promising transmission structure for ultrashort pulses. Numerical results for the modal dispersion of the SCPW are presented and compared to those of the conventional CPW, and a field-coupling theory is used to explain the evolution in the dispersion behavior. An evaluation based on the numerical analysis shows that a SCPW with properly controlled dispersion can exhibit a five times improvement in pulse transmission capability compared to the conventional CPW. Both computer simulations and experimental measurements show a substantial suppression in pulse distortion as well, compared to conventional CPWs     

A discrete-time queueing model of the shared buffer ATM switch with bursty arrivals

We model the shared buffer ATM switch as a discrete-time queueing system. The arrival process to each port of the ATM switch is assumed to be bursty and it is modelled by an interrupted Bernoulli process. The discrete-time queueing system is analyzed approximately. It is first decomposed into subsystems, and then each subsystem is analyzed separately. The results from the subsystems are combined together through an iterative scheme. The analysis of each subsystem involves the construction of the superposition of all the arrival processes to the switch. Comparisons with simulation data showed that the approximate results have a good accuracy.Supported in part by DARPA under Grant No. DAEA18-90-C-0039.Work done while on a sabbatical leave of absence at the Computer Science Department of North Carolina State University.     

New monolithic AGC amplifier stabilising output DC level for 560 Mbit/s optical transmission

A new AGC amplifier stabilising the output DC level is proposed and monolithically integrated using 1 ?m Si-bipolar IC technology. First, it is proven that the proposed AGC amplifier is about ten times superior to the conventional one in regard of output DC level stability. Next, it is confirmed that the IC, which exhibits a 720 MHz bandwidth, 39 dB maximum gain and 60 dB gain dynamic range, is feasible for 560 Mbit/s optical transmission.     

Use of the finite element method to determine epicardial from body surface potentials under a realistic torso model

This paper presents a new method of solution for the inverse problem in electrocardiography using the finite element procedure. It is an application of the authors' earlier work which derived a solution method by means of an integral equation under a generalized configuration of geometry and conductivity of the torso. Based on prior geometry information, the human torso region is discretized into a series offinite elements and, then, electric fields are computed when a set of linearly independent functions chosen as a basis is imposed on the epicardial surface. The set of these forward solutions defines the forward transfer coefficients which relate epicardial to body surface potentials. By the use of the forward transfer coefficients, a constrained least-squares estimate of the epicardial potential distribution can be obtained from measured body surface potentials. The solution method is examined through numerical experiments carried out for a realistic model of the human torso. It is demonstrated that the rapid decrease in voltage far from the heart generator makes this inverse problem ill conditioned and, as a result, the accuracy of the inverse epicardial potentials calculated depends greatly upon both the signal-to-noise ratio and the number of lead points in measuring the body surface potentials.     

Effects of bile acid feeding on hepatic deoxycholate 7α-hydroxylase activity in the hamster

In order to investigate the effects of bile acid feeding on hepatic microsomal deoxycholate 7α-hydroxylase activity, three different bile acids were administered (0.2% w/w in chow) to hamsters for two weeks. Deoxycholate 7α-hydroxylase activity was increased markedly by feeding of cholic acid (CA) and slightly by deoxycholic acid (DCA) Chenodeoxycholic acid (CDCA) had little effect on the enzyme activity. Feeding each of the bile acids significantly inhibited the activity of cholesterol 7α-hydroxylase in the order CDCA≥ DCA>CA. There was no correlation between deoxycholate 7α-hydroxylase activity and cholesterol 7α-hydroxylase activity. It is concluded that the activity of deoxycholate 7α-hydroxylase is up-regulated by feeding DCA and CA and that the mechanism seems to be different from that of cholesterol 7α-hydroxylase. The increased activity of hepatic deoxycholate 7α-hydroxylase by CA and DCA should be beneficial in minimizing the toxic effects of DCA in the hamster.     

Wideband and high-gain negative-feedback AGC amplifier for high-speed lightwave digital transmission systems

A negative-feedback AGC amplifier based on a new circuit configuration concept is proposed and monolithically integrated. The amplifier exhibits characteristics 2.5 times superior to those of the conventional AGC amplifier: 410 MHz bandwidth, 16 dB maximum gain and 18 dB gain dynamic range.