There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

/pdf/a-comprehensive-review-of-zno-materials-and-devices-21a3zjadem.pdf

A comprehensive review of zno materials and devices

Spread Spectrum It’s not just for breakfast anymore! Don't blame me, the title is the work of this month's guest columnist, Steve Bible, N7HPR (n7hpr@tapr.org). While cruising the net recently, I noticed a sudden bump in the number of times Spread Spectrum (SS) techniques were mentioned in the amateur digital areas. While QEX has discussed SS in the past, we haven't touched on it in this forum. Steve was a frequent cogent contributor, so I asked him to give us some background. Steve enlisted in the Navy in 1977 and became a Data Systems Technician, a repairman of shipboard computer systems. In 1985 he was accepted into the Navy’s Enlisted Commissioning Program and attended the University of Utah where he studied computer science. Upon graduation in 1988 he was commissioned an Ensign and entered Nuclear Power School. His subsequent assignment was onboard the USS Georgia, a trident submarine stationed in Bangor, Washington. Today Steve is a Lieutenant and he is completing a master’s degree in computer science at the Naval Postgraduate School in Monterey, California. His areas of interest are digital communications, amateur satellites, VHF/UHF contesting, and QRP. His research area closely follows his interest in amateur radio. His thesis topic is Multihop Packet Radio Routing Protocol Using Dynamic Power Control. Steve is also the AMSAT Area Coordinator for the Monterey Bay area. Here's Steve, I'll have some additional comments at the end.

http://ieeexplore.ieee.org/iel5/5/31355/01457623.pdf

Digital communications

Fundamentals of Plasmonics.- Electromagnetics of Metals.- Surface Plasmon Polaritons at Metal / Insulator Interfaces.- Excitation of Surface Plasmon Polaritons at Planar Interfaces.- Imaging Surface Plasmon Polariton Propagation.- Localized Surface Plasmons.- Electromagnetic Surface Modes at Low Frequencies.- Applications.- Plasmon Waveguides.- Transmission of Radiation Through Apertures and Films.- Enhancement of Emissive Processes and Nonlinearities.- Spectroscopy and Sensing.- Metamaterials and Imaging with Surface Plasmon Polaritons.- Concluding Remarks.

/pdf/plasmonics-fundamentals-and-applications-4syb9877sr.pdf

Plasmonics: Fundamentals and Applications

The potential integration of the optoelectronic capabilities of GaAs with the highly developed integrated circuit technology of Si has motivated a great deal of effort toward fabricating GaAs devices—particularly lasers—in epitaxial layers grown on Si substrates. A GaAs-on-Si detector can take advantage of the high carrier mobilities and optical absorption coefficient of GaAs and serve as a high-speed receiver in a composite GaAs/Si optoelectronic circuit.

High-speed GaAs PIN photodiodes grown on Si substrates by molecular beam epitaxy

There is disclosed an integrated optical detector comprising a semiconductor substrate having an optical waveguide formed integrally therewith and a photodetector made from the same semiconductor material as the waveguide and integrally coupled to it. The detector region is sensitive to light of the same wavelengths that can be transmitted through the waveguide region of the semiconductor without excessive absorption therein by virtue of the fact that after the waveguide is formed proton bombardment of the detector portion thereof is used to create optically active defect centers thereby shifting the effective absorption edge in the detector region. Where gallium arsenide is used as the semiconductor defect levels induced by implantation of high energy protons give rise to optical absorption between 6 micron and 0.9 micron. This results in detector action in the presence of a Schottkey barrier depletion layer. Detector response times less than 200 nanoseconds and external quantum efficiencies of 16 percent have been observed in the device.

Integrated optical detector

Several experiments [1,2] have noted recently that when an inverted two-level spin system was permitted to radiate spontaneously, the resulting oscillation was characterized by an appreciable amplitude modulation. The phenomenon was first believed to be the result of interference of different spin packets in an inhomogeneously broadened spectrum [1]. A theoretical analysis (which will be reported separately) shows that this is not the case. The spins are not independent but are coupled together by means of their radiation field. This explanation has since been by its original authors.

/pdf/radiation-damping-effects-in-two-level-maser-oscillators-40cdyewzqf.pdf

Radiation Damping Effects in Two Level Maser Oscillators

By combining a solid-state photoreaction model with the modal solutions of an optical waveguide, we simulate the refractive index change due to the photobleaching of CLD-1 chromophores in an amorphous polycarbonate microring resonator. The simulation agrees well with experimental results. The photobleaching quantum efficiency of the CLD-1 chromophores is determined to be 0.65%. The combined modeling of the electromagnetic wave propagation and photoreaction precisely illustrates the spatial and temporal evolution of the optical properties of the polymer material as manifested in the refractive index and their effects on the modal and physical properties of the optical devices.

/pdf/combined-electromagnetic-and-photoreaction-modeling-of-cld-1-3e1yw11ros.pdf

Combined electromagnetic and photoreaction modeling of CLD-1 photobleaching in polymer microring resonators

In this paper we compare the theoretical performances of two schemes of optical communication through the atmospheric turbulence: (1) heterodyne detection and (2) video detection. The signal-to-noise ratios (S/N) in the output current of a detector are expressed for both schemes in terms of the correlation function of the refractive index fluctuations of the turbulence. The results of a separate theoretical analysis of optical wave propagation through a random turbulence are used in order to obtain a numerical estimate of the performance criterion (S/N)_(2)(S/N)_(1) in terms of the length of propagation through the atmosphere, the turbulence strength, the wavelength of the optical wave, and the diameter of the receiving aperture.

Amnon Yariv

Papers

High-speed GaAs PIN photodiodes grown on Si substrates by molecular beam epitaxy

Integrated optical detector

Radiation Damping Effects in Two Level Maser Oscillators

Combined electromagnetic and photoreaction modeling of CLD-1 photobleaching in polymer microring resonators

Optical communication through random atmospheric turbulence.