All-fiber electrooptical mode-locking and tuning

Active mode-locking of a fiber laser with an all-fiber electrooptic modulator is demonstrated. A 1.4-V driving signal was used, creating subnanosecond single pulses at the fundamental frequency of the cavity (12 MHz). The modulator was a packaged Mach-Zehnder interferometer incorporating a poled twin-hole fiber in one of the arms. The switching voltage was 230 V at 1550 nm, with extinction ratio /spl sim/20 dB. The interferometer could be electrooptically tuned by 3.5 nm.     

Properties of products based on aluminum titanate and alumina

Conclusions Aluminum titanate containing additions of alumina and aluminum phosphate is a promising material for making articles with a low or practically zero coefficient of thermal expansion at temperatures of up to 500°C.It is of interest to do further work to find materials based on aluminum titanate, alumina and aluminum phosphate with zero coefficients of expansion in various temperature ranges.The addition of alumina and aluminum phosphate confers an adequate strength to the components of aluminum titanate, a high spalling resistance (including metal resistance) with a refractoriness of the order of 1930°C.     

Undulipodia, flagella and cilia

The term flagella is ambiguous. It refers to bacterial structures composed of flagellin protein and to eukaryotic structures composed of microtubule proteins and ATPase (tubulin and dynein). The fact that cilia are nearly identical to eukaryotic flagella and have nothing in common with prokaryotic flagella is not apparent from the terminology. It is proposed that the 30-year old suggestion of Smagina and reiterated by Kuznicki and others, be adopted: that cilia and eukaryotic flagella be called "undulipodia." The term flagella ought to be restricted to prokaryotic organelles, bacterial flagella and spirochaete axial filaments: solid structures composed of flagellin which protrude through the plasma membrane and lack intrinsic motility throughout their length. Undulipodia are defined as intrinsically motile intracellular structures showing a 9-fold symmetry in the pattern of arrangement of 24 nm diameter microtubules. They are limited to eukaryotes, members of the protoctist, animal and plant kingdoms.     

Managing Clouds, Smart Networks and Services: A Report on APNOMS 2011

This article presents a report on APNOMS 2011, which was held September 21–23, 2011 in Taipei, Taiwan. The theme of APNOMS 2011 was “Managing Clouds, Smart Networks and Services.”     

High cyclic fatigue performance of Al–Cu–Mg–Ag alloy under T6 and T840 conditions

High cyclic fatigue (HCF) behavior of an AA2139 alloy belonging to Al–Cu–Mg–Ag system in T6 and T840 conditions was examined. The T840 treatment involving cold rolling with a 40% reduction prior to peak ageing provides an increase in tensile strength compared with the T6 condition. However, fatigue lifetime for two material conditions was nearly the same since there is weak effect of thermomechanical processing on micro-mechanisms of crack initiation and growth.     

Photocurrent in a quantum channel with an impurity

The influence of electromagnetic radiation on electron transport in a quantum channel with a single short-range impurity is studied using the generalization of the Landauer-Büttiker method. It is shown that a direct photocurrent is induced in the system in the case of asymmetric impurity location. The dependence of the photocurrent on the electron chemical potential, impurity location, and radiation frequency is studied.     

Parallel implementation of the projector augmented plane wave method for charged systems

A parallel implementation of the projector augmented plane wave (PAW) method with the applications to several transition metal complexes is presented. A unique aspect of our PAW code is that it can treat both charged and neutral cluster systems. We discuss how this is achieved via accurate numerical treatment of the Coulomb Green's function with free space boundary conditions. The strategy for parallelizing the PAW code is based on distributing the plane wave basis across processors. This is a versatile approach and is implemented using a parallel three-dimensional Fast Fourier Transformation (FFT). We report parallel performance analysis of our program and of the three-dimensional FFT's and discuss large-scale parallelization issues of the PAW code. Using a series of transition metal monoxides and dioxides, as well as two iron aqueous complexes, it is shown that a free space PAW code can give structural parameters and energies in good accord with Gaussian based methods.     

Coupled States in a Curved Nanostructure

The spectrum of a Schrödinger operator with the zero-radius potential in a nanostructure of a constant total curvature is considered. Positions of the coupled states in a well of zero radius and the corresponding binding energy are determined. Their dependence on the scattering length and curvature is studied. The condition of the formation of the coupled state is determined.