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

We present a novel approach to photoconductive sampling with a resolution which is virtually independent of the carrier lifetime and is governed solely by the circuit‐limited gap charging time. Using photoconductors with a carrier lifetime of 150 ps, accurate measurement of a 65‐ps‐wide electrical signal is demonstrated and the actual resolution is believed to be 10 ps.

/pdf/differential-photoconductive-sampling-with-a-resolution-ivgxzy1olc.pdf

Differential photoconductive sampling with a resolution independent of carrier lifetime

A pseudo-nondiffracting beam (PNDB) is characterized by an almost constant intensity along a finite propagation distance and a beamlike shape in its transverse dimensions. In other words, the intensity distribution is distributed as a sword of light. There are several methods for achieving a PNDB. From the viewpoint of geometrical optics, a sword beam has been demonstrated by axicon.1 With diffraction theory, it has been shown that the Bessel beam2 and a beam diffracted from the holographic axilens3 behave as PNDB’s. Other kinds of PNDB have been obtained by numerical iterative methods.4,5 Multiplexing a few PNDB’s has been achieved also by numerical iterative methods,6 and one-dimensional PNDB’s have been found analytically7 and numerically.8 In this paper we propose a new PNDB that is general in the sense that in the limit, when its parameters go to infinity, it converges to the Bessel beam. It consists of four independent parameters, each affecting the beam’s transverse width, sidelobe height, and longitudinal interval length. The proposed PNDB’s are created by radial harmonic functions (RHF’s) coded on Fourier holograms. The RHF can be used as a phase-only pupil filter for increasing the depth of focus of imaging systems, as demonstrated in Section 5. The relations between the hologram and the resulting beam are analyzed in Section 3. Knowing the mutual dependence between the holograms and the PNDB’s enables us to shift and rotate the beams in space, as well as change their scale, by changing a few parameters of the holograms’ distribution. These effects are also demonstrated in Section 5.

Pseudo-nondiffracting beams generated by radial harmonic functions: erratum

Room-temperature operation of distributed Bragg-reflector lasers

We present experimental results of field‐enhanced photorefractive two‐beam coupling and gain in Cr‐doped strontium barium niobate crystals and its dependence on dopant concentrations. Increases in the exponential gain factor by more than a factor of 2 were observed by applying a field of up to 10 kV/cm. This property has potential applications such as switchable optical phase conjugators, limiters, and thresholding devices.

Enhanced photorefractive gain in Cr-doped strontium barium niobate with an external dc electric field

A method of designing phase shifting masks with improved resolution. Auxiliary transmissive phase regions with properly selected locations and dimensions are introduced to eliminate unwanted interference patterns. A usual opaque region between the transmissive features that are phase-conflicting to one another is partially or entirely replaced with a transmissive region of an opposite phase with respect to the phase of the transmissive features. In positive photoresist layouts, the light-absorbing features are partially or entirely made transmissive while an opposite and uniform phase is maintained throughout the transmissive background. Segmenting features with at least one auxiliary phase region and adjusting attenuation of different features can further improve the performance.

Amnon Yariv

Papers

Differential photoconductive sampling with a resolution independent of carrier lifetime

Pseudo-nondiffracting beams generated by radial harmonic functions: erratum

Room-temperature operation of distributed Bragg-reflector lasers

Enhanced photorefractive gain in Cr-doped strontium barium niobate with an external dc electric field

Phase-shifting masks for photolithography