Long-term reliability of transmission loss in optical fiber cables

Increased optical-fiber cable losses due to hydrogen are discussed. A mathematical model is developed to predict the growth of hydrogen concentration in the cable, which is determined by the evolution from organic cable materials and permeation through the cable sheath. This cable model, together with the measured parameters for the cable materials, explains the measured results. Design criteria for the allowable hydrogen evolution from cable materials and for the cable sheath structure are established on the basis of the model     

Senile dementia-Alzheimer's type and estrogen

Some reports have suggested the ameliorative effects of estrogens on clinical symptoms, such as short memory, in women suffering from senile dementia-Alzheimer's type, in vivo. The action mechanism of estrogen remains to be clarified, but 1) an anti-depressive effect, 2) improvement of cerebral blood flow, 3) direct stimulation of neuron, 4) development of gliacyte and 5) suppression of apolipoprotein E have been suggested. Some mechanisms may be combined, contributing to the beneficial effects on clinical symptoms.     

Design Considerations for Traveling-Wave Single-Pole Multithrow MMIC Switch Using Fully Distributed FET

The circuit design considerations for the traveling-wave switch (TWSW) single-pole double-throw (SPDT) monolithic microwave integrated circuit (MMIC) utilizing a fully distributed FET (FD-FET) are presented here for the first time. The normalized length of the impedance transformer for a single-pole multithrow TWSW using the FD-FET is found to be less than a quarter-wavelength at the operating frequency. Unlike the TWSW using lumped FETs, the TWSW with the FD-FET offers the advantage of no design limits regarding such frequency characteristics as bandwidth and group delay. The newly developed SPDT TWSW MMIC using the 400-mum-gate finger FD-FET delivers broadband characteristics over more than an octave frequency range with highly reliable MMIC technology. The newly developed SPDT MMIC switch provides low insertion loss of less than 2.1 dB and high isolation of over 25.5 dB from 38 to 80 GHz, coupled with the benefit of very small size     

The weight of the reproductive organs, hypophysis and thyroid of male cynomolgus monkeys. (Macaca fascicularis) (author's transl)

The present short paper deals with the weight of the male reproductive organs of wild-imported cynomolgus monkeys, including the testes, epididymides, ductus deferens, vesicula seminalis prostata, bulbo urethralis and penis. In addition, the size of the testes and the weight of the thyroid and hypophysis are also presented.     

RF HBT oscillators with low-phase noise and high-power performance utilizing a (/spl lambda//4/spl plusmn//spl delta/) open-stubs resonator

This paper presents a new type of transmission-line resonator and its application to RF (microwave and millimeter-wave) heterojunction bipolar transistor (HBT) oscillators. The resonator is a parallel combination of two open stubs having length of /spl lambda//4/spl plusmn//spl delta/(/spl delta//spl Lt//spl lambda/), where /spl lambda/ is a wavelength at a resonant frequency. The most important feature of this resonator is that the coupling coefficient (/spl beta//sub C/) can be controlled by changing /spl delta/ while maintaining unloaded Q-factor (Q/sub u/) constant. Choosing a small value of /spl delta/ allows us to reduce /spl beta//sub C/ or equivalently to increase loaded Q-factor (Q/sub L/). Since coupling elements such as capacitors or electromagnetic gaps are not needed, /spl beta//sub C/ and Q/sub L/ can be precisely controlled based on mature lithography technology. This feature of the resonator proves useful in reducing phase noise and also in enhancing output power of microwave oscillators. The proposed resonator is applied to 18-GHz and 38-GHz HBT oscillators, leading to the phase noise of -96-dBc/Hz at 100-kHz offset with 10.3-dBm output power (18-GHz oscillator) and -104-dBc/Hz at 1-MHz offset with 11.9 dBm (38-GHz oscillator). These performances are comparable to or better than state-of-the-art values for GaAs- or InP-based planar-circuit fundamental-frequency oscillators at the same frequency bands.     

Advanced TFA-MOD process of high critical current YBCO films for coated conductors

Although the metalorganic deposition (MOD) process using metal trifuluoroacetete (TFA) is considered to be a strong candidate due to its low cost and high J_c performance as a fabrication process for coated conductors of YBa₂Cu₃O_7 − x (YBCO), the long calcination time of 10 h for 300 nm YBCO thickness was a problem that needed to be solved in the case of the MOD process using the TFA salts for all elements (all TFA solution). In this study, in order to shorten the calcination time, a new combination of starting materials was developed. Through the investigation of the generation rate of hydro fluoride (HF) gas during calcination, it was found that the high generation rate at a high heating rate is the reason for the bubbling which prevents an increase of the heating rate. Therefore, the amount of fluorine (F) in the starting material was reduced by using the Cu-salt without F while maintaining the basic crystallization reaction in this process. A new heating process using these materials has been developed. Consequently, the calcination time was shortened to 40% using the All TFA solution and an overall transport I_c value of 292 A for 1 cm width was obtained (77 K in self-field).     

Development of the Design Codes Grounded on the Performance-Based Design Concept in Japan

This paper traces the recent introduction of performance-based design (PBD) into Japanese design codes (especially geotechnical design codes) and describes the distinguishing characteristics of PBD codes. An overview is provided for source documents that initiated the concept of performance-based design, and consideration is given to the impact of the WTO/TBT Agreement and Japanese government policies on this issue. Three design codes are introduced to explain the development of PBD codes in Japan: JGS4001-2004 ‘Principles for Foundation Design Grounded on a Performance-Based Design Concept’ (Geocode 21); Technical Standards for Port and Harbor Facilities (TSPHF); and Specifications for Highway Bridges (SHB). The first one is a model code established by JGS, whereas the latter two are regulatory design codes used in practice. Performance-based design is now recognized as the most important concept in code drafting and the majority of design codes will introduce this concept at least partially. Thus, PBD is a key concept for understanding the current Japanese design codes.     

50-GHz-bandwidth baseband amplifiers using GaAs-based HBTs

Baseband amplifiers of 50 GHz, using high-performance AlGaAs/InGaAs HBTs with regrown base contacts, have been demonstrated. The transimpedance amplifier achieved a bandwidth of 50.8 GHz with a gain of 11.6 dB. The transimpedance characteristics were of 49.3-GHz bandwidth with a 43.7-dBΩ transimpedance gain. The resistive and mirror Darlington feedback amplifiers, respectively, achieved a bandwidth of 54.7 GHz with a gain of 8.2 dB and a bandwidth of more than 60.0 GHz with a gain of 6.3 dB. To date, these are the widest bandwidths reported for lumped-circuit-design amplifiers. These results suggest the great potential of these amplifiers for use in future optical communication, microwave and millimeter-wave applications     

The human S mu bp-2, a DNA-binding protein specific to the single-stranded guanine-rich sequence related to the immunoglobulin mu chain switch region

We have cloned the cDNA encoding the human homologue of S mu bp-2, which binds to single-stranded DNA with 5'-phosphorylated guanine-rich sequences related to the immunoglobulin mu chain switch (S mu) region. The deduced amino acid sequences of the mouse and human S mu bp-2 are 76.5% homologous and contain motifs conserved among helicases. We have identified a domain essential for DNA binding at residues 638-786. The binding domain is less conserved (63% homologous) than the putative catalytic domain of N-terminal half containing most of the helicase motifs (85% homologous). The human and mouse S mu bp-2 have similar, although slightly different, binding specificities. Although the mouse S mu bp-2 preferentially binds to the mouse S mu motif (GGGGT), the human S mu bp-2 binds equally well to the human (GGGCT) and mouse S mu motifs. The human S mu bp-2 gene was mapped to chromosome 11 q13.2-q13.4 by in situ hybridization.