42,119 research outputs found
Simple Coherent Polarization Manipulation Scheme for Generating High Power Radially Polarized Beam
We present a simple novel scheme that converts a Gaussian beam into an
approximated radially polarized beam using coherent polarization manipulation
together with Poynting walk-off in birefringent crystals. Our scheme alleviates
the interferometric stability required by previous schemes that implemented
this coherent mode summation using Mach-Zehnder-like interferometers. A
symmetrical arrangement of two walk-off crystals with a half-wave plate, allows
coherence control even when the laser has short temporal coherence length. We
generated 14 watts of radially polarized beam from an Ytterbium fiber laser,
only limited by the available fiber laser power.Comment: Submitting for publicatio
Microstructural evolution in materials during thermal processing
Copyright © 2012 Joseph K. L. Lai et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.This article is made available through the Brunel Open Access Publishing Fund
A functional RNase P protein subunit of bacterial origin in some eukaryotes
RNase P catalyzes 5′-maturation of tRNAs. While bacterial RNase P comprises an RNA catalyst and a protein cofactor, the eukaryotic (nuclear) variant contains an RNA and up to ten proteins, all unrelated to the bacterial protein. Unexpectedly, a nuclear-encoded bacterial RNase P protein (RPP) homolog is found in several prasinophyte algae including Ostreococcus tauri. We demonstrate that recombinant O. tauri RPP can functionally reconstitute with bacterial RNase P RNAs (RPRs) but not with O. tauri organellar RPRs, despite the latter’s presumed bacterial origins. We also show that O. tauri PRORP, a homolog of Arabidopsis PRORP-1, displays tRNA 5′-processing activity in vitro. We discuss the implications of the striking diversity of RNase P in O. tauri, the smallest known free-living eukaryote.Ministerio de Ciencia e Innovación European Regional Fund BFU2007-60651Junta de AndalucÃa P06-CVI-01692National Science Foundation MCB-0238233 MCB-0843543European Union ASSEMBLE 22779
molecular ions can exist in strong magnetic fields
Using the variational method it is shown that for magnetic fields G there can exist a molecular ion .Comment: LaTeX, 7 pp, 1 table, 4 figures. Title modified. Consideration of the
longitudinal size of the system was adde
Improved Memoryless RNS Forward Converter Based on the Periodicity of Residues
The residue number system (RNS) is suitable for DSP architectures because of its ability to perform fast carry-free arithmetic. However, this advantage is over-shadowed by the complexity involved in the conversion of numbers between binary and RNS representations. Although the reverse conversion (RNS to binary) is more complex, the forward transformation is not simple either. Most forward converters make use of look-up tables (memory). Recently, a memoryless forward converter architecture for arbitrary moduli sets was proposed by Premkumar in 2002. In this paper, we present an extension to that architecture which results in 44% less hardware for parallel conversion and achieves 43% improvement in speed for serial conversions. It makes use of the periodicity properties of residues obtained using modular exponentiation
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