Efficient implementation of 90 degrees phase shifter in FPGA

In this article, we present an efficient way of implementing 90 phase shifter using Hilbert transformer with canonic signed digit (CSD) coefficients in FPGA. It is implemented using 27-tap symmetric finite impulse response (FIR) filter. Representing the filter coefficients by CSD eliminates the need for multipliers and the filter is implemented using shifters and adders/subtractors. The simulated results for the frequency response of the Hilbert transformer with infinite precision coefficients and CSD coefficients agree with each other. The proposed architecture requires less hardware as one adder is saved for the realization of every negative coefficient compared to convectional CSD FIR filter implementation. Also, it offers a high accuracy of phase shift

Comments and Suggestions for Improvement of the Archon Genomics X PRIZE Validation Protocol

This document is a comment on the X PRIZE validation protocol written by Kedes et al. (2011). We propose several modifications which we think will improve the fairness and transparency of the contest while keeping the cost of the validation process under control

Genes, Transposable Elements, and Small RNAs: Studying the Evolution of Diverse Genomic Components

The evolution of genes and genomes has attracted great interest. The research presented here is an examination of genomes at three distinct levels, protein evolution, gene family evolution, and TE content regulation. First at a genetic level, I conducted an analysis of the salivary androgen-binding proteins (ABPs). I focused on comparing patterns of molecular evolution between the Abpa gene expressed in the submaxillary glands of species of New World and Old World muroids and found that in both sets of rodents, the Abpa gene expressed in the submaxillary glands appear to be evolving under sexual selection, suggesting ABP might play a similar biological role in both systems. Thus, ABP could be involved with mate recognition and species isolation in New World as well as Old World muroids. Second I examined the largest gene family in vertebrate olfactory receptors (ORs) among birds and reptiles. I found that the number of intact OR genes in sauropsid genomes analyzed ranged over an order of magnitude, from 108 in the lizard to over 1000 in turtles. My results suggest that different sauropsid lineages have highly divergent OR repertoire compositions. These differences suggest that varying rates of gene birth and death, together with selection related to diverse natural histories, have shaped the unique OR repertoires observed across sauropsid lineages. Lastly, I studied the interactions between transposable elements (TEs) and PIWI-interacting RNAs (piRNAs) among laurasiatherian mammals. piRNAs are predominantly expressed in germlines and reduce TE expression and risks associated with their mobilization. I found that within TE types, families that are the most highly transcribed appear to elicit the strongest ping-pong response. This was most evident among LINEs, but the relationships between expression and PPE was more complex among SINEs. I also found that the abundance of insertions within piRNAs clusters strongly correlated with genome insertions and there was little evidence to suggest that piRNA clusters regulated TE silencing. In summary, the piRNA response is efficient at protecting the genome against TE mobility, particularly LINEs, and can have an evolutionary impact on the TE composition of a genome