Survey of switching techniques in high-speed networks and their performance

One of the most promising approaches for high speed networks for integrated service applications is fast packet switching, or ATM (asynchronous transfer mode). ATM can be characterized by very high speed transmission links and simple, hard-wired protocols within a network. To match the transmission speed of the network links, and to minimize the overhead due to the processing of network protocols, the switching of cells is done in hardware switching fabrics in ATM networks. A number of designs have been proposed for implementing ATM switches. Although many differences exist among the proposals, the vast majority of them are based on self-routeing multistage interconnection networks. This is because of the desirable features of multi-stage interconnection networks such as self-routeing capability and suitability for VLSI implementation. Existing ATM switch architectures can be classified into two major classes: blocking switches, where blockings of cells may occur within a switch when more than one cell contends for the same internal link, and non-blocking switches, where no internal blocking occurs. A large number of techniques have also been proposed to improve the performance of blocking and non-blocking switches. In this paper, we present an extensive survey of the existing proposals for ATM switch architectures, focusing on their performance issues.     

Westernized food habits and concentrations of serum lipids in the Japanese

It has recently been reported that there exists a new 'RING-finger' protein family among the zinc-finger (Zf) proteins. Previously, we had isolated the mouse Mel-18 cDNA (mMel-18) encoding the nuclear RING-finger protein that exhibits an ability to bind to a nonspecific DNA column. Here, we have isolated and characterized the human Mel-18 cDNA (hMel-18) using the mMel-18 cDNA as a probe. The deduced hMel-18 protein contains 344 amino acids (38 kDa) with a RING-finger motif, a helix-loop-helix (HLH)-like structure and a Pro/Ser-rich region. The hMel-18 gene is conserved among vertebrates. Its mRNA is highly expressed in placenta, lung and kidney, but the level is low in liver, pancreas and skeletal muscle. Using in situ hybridization, we mapped hMel-18 to band q22 of chromosome 12. It is possible that the Mel-18/bmi-1 gene family represents a mammalian homologue of the Drosophila polycomb gene group.     

Current density limitation and diffusion boundary layer calculation using CFD method

The knowledge of limiting current density and thickness of diffusion boundary layer is particularly important in improving space-time-yield of electrolysis and especially of high current-density electrolysis. Both natural and forced convection of electrolyte flow are considered in the presented computational fluid dynamics model for calculation of these values. Natural convection is modeled by implementation of a source term at the cathode surface for copper concentration according to Faraday’s law, which allows calculation of electrolyte density for each volume cell of the grid. Forced convection is considered as flow of electrolyte through the cell generated by electrolyte inlet and outlet. By variation of current density, the limiting current density can be calculated with a copperion concentration of zero at the cathode surface after reaching the steady-state conditions in electrolyte. Time dependency of diffusion boundary layer thickness is shown for a chosen cell geometry. Literature data and measured and calculated values of both quantities are in good agreement.     

Excessive closure of the right eye: a new sign of infarction in the territory of the ipsilateral right middle cerebral artery

In right middle cerebral territory infarction a new sign, excessive closure of the right eye ipsilateral to the lesion and mild closure of the left eye on command, was noted. The excessive ipsilateral eye closure was not observed on spontaneous eye closure.     

Molecular neurogenetics of chemotaxis and thermotaxis in the nematode Caenorhabditis elegans

Chemotaxis and thermotaxis in Caenorhabditis elegans are based on the chemical senses (smell and taste) and the thermal sense, respectively, which are important for the life of the animal. Laser ablation experiments have allowed identification of sensory neurons and some interneurons required for these senses. Many mutants that exhibit various abnormalities have been isolated and analyzed. These studies have predicted novel signaling pathways whose components include a putative odorant specific transmembrane receptor (ODR-10) and a cyclic nucleotide-gated channel (TAX-4/TAX-2) functioning in taste and thermosensation as well as in smell. The emerging picture of the mechanisms of sensory transduction in C. elegans seems to be basically similar to what is known of visual and olfactory sensory transduction in vertebrates. Thus, molecular and cellular analyses of chemotaxis and thermotaxis in C. elegans have proved useful and will continue to provide significant implications for the molecular basis of sensory systems in higher animals.     

2,4-Dichlorophenoxyacetic acid action on in vitro protein synthesis and its relation to polyamines

The effect of 2,4-dichlorophenoxyacetic acid (2,4-D) on the in vitro synthesis of proteins was studied in Chinese hamster ovary cells. A remarkable inhibition of the synthesis of proteins was observed when cells grew for 24 h in presence of 1 mM 2,4-D. This effect was reversed by adding 0.1 mM of the three polyamines (putrescine, spermidine and spermine) to the cultured cells. The mRNA is not altered, indicating that the 2,4-D action is located at a different locus, which may be the ribosomes. From these studies, one can speculate that the alterations in the protein synthesis may be a consequence of the effect of 2,4-D on the polyamine metabolism.     

A transmit/receive IF chip set for WCDMA mobiles in 0.35 /spl mu/m CMOS

An implementation of the IF section of WCDMA mobile transceivers with a set of two chips fabricated in an inexpensive 0.35-/spl mu/m two-poly three-metal CMOS process is presented. The transmit/receive chip set integrates quadrature modulators and demodulators, wide dynamic range automatic gain control (AGC) amplifiers, with linear-in-decibel gain control, and associated circuitry. This paper describes the problems encountered and the solutions envisaged to meet stringent specifications, with process and temperature variations, thus overcoming the limitations of CMOS devices, while operating at frequencies in the range of 100 MHz-1 GHz. Detailed measurement results corroborating successful application of the new techniques are reported. A receive AGC dynamic range of 73 dB with linearity error of less than /spl plusmn/2 dB and spread of less than 5 dB for a temperature range of -30/spl deg/C to +85/spl deg/C in the gain control characteristic has been measured. The modulator measurement shows a carrier suppression of 35 dB and sideband/third harmonic suppression of over 46 dB. The core die area of each chip is 1.5 mm/sup 2/.     

Pulse-width tunable, self-frequency conversion of short opticalpulses over 200 nm based on supercontinuum generation

Self-frequency conversion of ultrashort optical pulses into arbitrary multiwavelength components without the use of a pump is achieved by using supercontinuum generation. Frequency conversion of a randomly-modulated 1.535-1.560 μm, 2.5 ps pulse stream at 6.3 Gbit/s into 1.41-1.64 μm, 0.29-1.0 ps pulse streams is demonstrated for the first time. The method features ultrawide tunability of over 200 nm, and multiwavelength, pulsewidth-tunable output for flexible WDM distribution networks