InP D-HBT ICs for 40-Gb/s and higher bitrate lightwave transceivers

The combination of device speed (f/sub T/, f/sub max/ > 150 GHz) and breakdown voltage (V/sub bceo/ > 8 V) makes the double heterojunction bipolar InP-based transistor (D-HBT) an attractive technology to implement the most demanding analog functions of 40-Gb/s transceivers. This is illustrated by the performance of a number of analog circuits realized in an InP D-HBT technology with an 1.2- or 1.6-/spl mu/m-wide emitter finger: a low phase noise push-push voltage-controlled oscillator with -7-dBm output power at 146 GHz, a 40-GHz bandwidth and low-jitter 40-Gb/s limiting amplifier, a lumped 40-Gb/s limiting driver amplifier with 4.5-V/sub pp/ differential output swing, a distributed 40-Gb/s driver amplifier with 6-V/sub pp/ differential output swing, and a number of distributed preamplifiers with up to 1.3-THz gain-bandwidth product.     

Quantisation noise control in perceptual audio coding using low selectivity filter banks

The problem of computing, in a subband audio coder, the maximum quantisation noise power that can be injected in each band to ensure transparent coding when low selectivity filter banks are used, is addressed. A low complexity strategy, taking into account the frequency responses of the synthesis filter bank, is proposed for achieving an overall distortion due to quantisation noise always below the masking threshold (provided by a psycho-acoustic model) for any length prototype filters.     

Magnetic effects of direct ion implantation of Mn and Fe into p-GaN

In p-GaN implanted with Mn (3×10¹⁶ cm⁻² at 250 keV), the material after annealing shows ferromagnetic properties below 250 K. Cross-sectional transmission electron microscopy (TEM) revealed the presence of platelet structures with hexagonal symmetry. These regions are most likely Ga_xMn_1−xN, which produce the ferromagnetic contribution to the magnetization. In p-GaN implanted with Fe, the material after annealing showed ferromagnetic properties at temperatures that were dependent on the Fe dose, but were below 200 K in all cases. In these samples, TEM and diffraction analysis did not reveal any secondary phase formation. The results for the Fe implantation are similar to those reported for Fe doping during epitaxial growth of GaN.     

An optical instrumentation using a sensor with a sensordummyagainst noises on sensor and transmission line

This short paper discusses the method of effectively canceling equal status normal mode noise not only on a sensor line but also on a transmission line of an optical instrument using a sensor with a sensordummy resistance     

1/f noise sources

This survey deals with 1/f noise in homogeneous semiconductor samples. A distinction is made between mobility noise and number noise. It is shown that there always is mobility noise with an α value with a magnitude in the order of 10^-4. Damaging the crystal has a strong influence on α, α may increase by orders of magnitude. Some theoretical models are briefly discussed none of them can explain all experimental results. The α values of several semiconductors are given. These values can be used in calculations of 1/f noise in devices     

Metal diffraction gratings as laser power or energy dividers

The authors survey published results on the application of metal diffraction gratings as laser power or energy dividers when the laser beam is split into two approximately equal pans. The normal incidence of laser radiation on metal diffraction gratings of various profiles in the case of three propagating diffraction orders n=0, ±1 is discussed, along with the case of oblique incidence with only two propagating diffraction orders n=0 and n =–1.Translated from Izmeritel'naya Tekhnika, No. 2, pp. 22–26, February, 1994.     

Microstructure of Feta Cheese Made Using Different Cultures as Determined by Confocal Scanning Laser Microscopy

ABSTRACT: The objective of this work was to observe the microstructure of feta cheese using confocal scanning laser microscopy. Low fat cheese and cheese containing capsule-producing cultures were made. The protein network was observed using the reflectance mode of the confocal microscope. Fat was stained by Nile red dye diluted with whey. More even distribution of fat with a larger number of smaller globules was observed in cheese made with noncapsule-forming culture compared to that made with the capsule-forming culture. Nonfat cheese had compact structure when made with noncapsule-forming culture which contrasted with the open structure observed in cheese made with the capsule-forming culture     

Streptococcal infection in the pathogenesis of Beh?et's disease and clinical effects of minocycline on the disease symptoms

Although the precise pathoetiology of Beh?et's disease (BD) remains obscure, patients with BD have a high incidence of chronic infectious foci, indicating an enhanced susceptibility to chronic tonsillitis, and dental caries. Sometimes, clinical symptoms appear after treatment of these foci in BD patients. It is believed that BD might be related to an allergic reaction to a bacterial infection in view of the many clinical symptoms, especially the presence of aphthous and genital ulcerations. An attempt to obtain cutaneous responses to bacterial antigens has been carried out using various vaccines developed from bacteria isolated from the ulcerative lesions and oral cavities of BD patients. BD patients often show intense hypersensitivity to various strains of streptococci, not only by their cutaneous reactions but also by in vitro testing. In this report, we describe our previous studies on the correlation between streptococcal antigens and the pathogenesis of BD and also discuss the recent reports of other authors. The intense hypersensitivity to streptococcal antigens acquired after streptococcal infection is thought to play an important role in the appearance of symptoms in BD patients since the production of pro-inflammatory cytokines by peripheral blood mononuclear cells (PBMC) was enhanced when stimulated with streptococcal antigen in a culture system. Minocycline, an antibiotic to which certain strains of streptococci are sensitive, reduced the frequency of clinical symptoms in BD patients as well as the production of pro-inflammatory cytokines by BD-PBMC stimulated with streptococcal antigen.     

Estramustine and estrone analogs rapidly and reversibly inhibit deoxyribonucleic acid synthesis and alter morphology in cultured human glioblastoma cells

Estramustine is an estradiol-based agent that has been shown to accumulate in human glioma cells, resulting in a concentration-dependent alteration in cell size and shape within minutes and an inhibition of proliferation over 3 to 6 days. We evaluated human glioblastoma cultures with [3H]thymidine incorporation assays to determine estramustine's early effects on deoxyribonucleic acid synthesis in these tumors. Because estramustine shares a common structural motif with other antimicrotubule drugs, we synthesized four A-ring conjugates of estrone that contained a carbamate moiety but lacked nitrogen mustard. These analogs were examined by [3H]thymidine incorporation and compared with vinblastine. Greater than 70% inhibition of [3H]thymidine incorporation occurred within 1 hour of treatment with estramustine at 10(-5) mol/L, which increased to 80% inhibition at 4 hours. Ethyl carbamate JE208 was nearly as effective as estramustine in inhibiting deoxyribonucleic acid synthesis, and both were more effective than vinblastine. The inhibitory effects of estramustine and estrone analogs were reversible; vinblastine was not reversible. Although estramustine and JE208 induced similar antiproliferative and morphological changes in glioblastoma cells that persisted for at least 4 days, there was a modest recovery of morphology and thymidine incorporation with JE208 after prolonged treatment. The common findings with estramustine and JE208 suggest that these agents may have a similar mechanism of action and form the basis for the investigation of new agents that may rapidly and reversibly inhibit glioblastoma.