High Performance Power Spectrum Analysis Using a FPGA Based Reconfigurable Computing Platform

Power-spectrum analysis is an important tool providing critical information about a signal. The range of applications includes communication-systems to DNA-sequencing. If there is interference present on a transmitted signal, it could be due to a natural cause or superimposed forcefully. In the latter case, its early detection and analysis becomes important. In such situations having a small observation window, a quick look at power-spectrum can reveal a great deal of information, including frequency and source of interference. In this paper, we present our design of a FPGA based reconfigurable platform for high performance power-spectrum analysis. This allows for the real-time data-acquisition and processing of samples of the incoming signal in a small time frame. The processing consists of computation of power, its average and peak, over a set of input values. This platform sustains simultaneous data streams on each of the four input channels.Comment: 5 pages, 3 figures. Published in the Proceedings of the IEEE International conference on Reconfigurable Computing and FPGAs (ReConFig 2006). Article also available at http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4100006&isnumber=409995

A High Speed Networked Signal Processing Platform for Multi-element Radio Telescopes

A new architecture is presented for a Networked Signal Processing System (NSPS) suitable for handling the real-time signal processing of multi-element radio telescopes. In this system, a multi-element radio telescope is viewed as an application of a multi-sensor, data fusion problem which can be decomposed into a general set of computing and network components for which a practical and scalable architecture is enabled by current technology. The need for such a system arose in the context of an ongoing program for reconfiguring the Ooty Radio Telescope (ORT) as a programmable 264-element array, which will enable several new observing capabilities for large scale surveys on this mature telescope. For this application, it is necessary to manage, route and combine large volumes of data whose real-time collation requires large I/O bandwidths to be sustained. Since these are general requirements of many multi-sensor fusion applications, we first describe the basic architecture of the NSPS in terms of a Fusion Tree before elaborating on its application for the ORT. The paper addresses issues relating to high speed distributed data acquisition, Field Programmable Gate Array (FPGA) based peer-to-peer networks supporting significant on-the fly processing while routing, and providing a last mile interface to a typical commodity network like Gigabit Ethernet. The system is fundamentally a pair of two co-operative networks, among which one is part of a commodity high performance computer cluster and the other is based on Commercial-Off The-Shelf (COTS) technology with support from software/firmware components in the public domain.Comment: 19 pages, 4 eps figures, To be published in Experimental Astronomy (Springer

Long-term study of extreme giant pulses from PSR B0950+08 with AARTFAAC

We report on the detection of extreme giant pulses (GPs) from one of the oldest-known pulsars, the highly variable PSR B0950+08, with the Amsterdam-ASTRON Radio Transient Facility And Analysis Centre (AARTFAAC), a parallel transient detection instrument operating as a subsystem of the LOw Frequency ARray (LOFAR). During processing of our Northern Hemisphere survey for low-frequency radio transients, a sample of 275 pulses with fluences ranging from 42 to 177 kJy ms were detected in one-second snapshot images. The brightest pulses are an order of magnitude brighter than those previously reported at 42 and 74 MHz, on par with the levels observed in a previous long-term study at 103 MHz. Both their rate and fluence distribution differ between and within the various studies done to date. The GP rate is highly variable, from 0 to 30 per hour, with only two three-hour observations accounting for nearly half of the pulses detected in the 96 h surveyed. It does not vary significantly within a few-hour observation, but can vary strongly one from day to the next. The spectra appear strongly and variably structured, with emission sometimes confined to a single 195.3 kHz subband, and the pulse spectra changing on a timescale of order 10 min.Comment: 10 pages, 9 figures, 1 table. Submitted to MNRA

Perspective on nanochannels as cellular mediators in different disease conditions

Abstract Tunnelling nanotubes (TNTs), also known as membrane nanochannels, are actin-based structures that facilitate cytoplasmic connections for rapid intercellular transfer of signals, organelles and membrane components. These dynamic TNTs can form de novo in animal cells and establish complex intercellular networks between distant cells up to 150 μm apart. Within the last decade, TNTs have been discovered in different cell types including tumor cells, macrophages, monocytes, endothelial cells and T cells. It has also been further elucidated that these nanotubes play a vital role in diseased conditions such as cancer, where TNT formation occurs at a higher pace and is used for rapid intercellular modulation of chemo-resistance. Viruses such as HIV, HSV and prions also hijack the existing TNT connections between host cells for rapid transmission and evasion of the host immune responses. The following review aims to describe the heterogeneity of TNTs, their role in different tissues and disease conditions in order to enhance our understanding on how these nanotubes can be used as a target for therapies

Stable Dispersions of Covalently Tethered Polymer Improved Graphene Oxide Nanoconjugates as an Effective Vector for siRNA Delivery

Conjugates of poly­(amidoamine) (PAMAM) with modified graphene oxide (GO) are attractive nonviral vectors for gene-based cancer therapeutics. GO protects siRNA from enzymatic cleavage and showed reasonable transfection efficiency along with simultaneous benefits of low cost and large scale production. PAMAM is highly effective in siRNA delivery but suffers from high toxicity with poor in vivo efficacy. Co-reaction of GO and PAMAM led to aggregation and more importantly, have detrimental effect on stability of dispersion at physiological pH preventing their exploration at clinical level. In the current work, we have designed, synthesized, characterized and explored a new type of hybrid vector (GPD), using GO synthesized via improved method which was covalently tethered with poly­(ethylene glycol) (PEG) and PAMAM. The existence of covalent linkage, relative structural changes and properties of GPD is well supported by Fourier transform infrared (FTIR), UV–visible (UV–vis), Raman, X-ray photoelectron (XPS), elemental analysis, powder X-ray diffraction (XRD), thermogravimetry analysis (TGA), dynamic light scattering (DLS), and zeta potential. Scanning electron microscopy (SEM), and transmission electron microscopy (TEM) of GPD showed longitudinally aligned columnar self-assembled ∼10 nm thick polymeric nanoarchitectures onto the GO surface accounting to an average size reduction to ∼20 nm. GPD revealed an outstanding stability in both phosphate buffer saline (PBS) and serum containing cell medium. The binding efficiency of EPAC1 siRNA to GPD was supported by gel retardation assay, DLS, zeta potential and photoluminescence (PL) studies. A lower cytotoxicity with enhanced cellular uptake and homogeneous intracellular distribution of GPD/siRNA complex is confirmed by imaging studies. GPD exhibited a higher transfection efficiency with remarkable inhibition of cell migration and lower invasion than PAMAM and Lipofectamine 2000 suggesting its role in prevention of breast cancer progression and metastasis. A significant reduction in the expression of the specific protein against which siRNA was delivered is revealed by Western blot assay. Furthermore, a pH-triggered release of siRNA from the GPD/siRNA complex was studied to provide a mechanistic insight toward unloading of siRNA from the vector. Current strategy is a way forward for designing effective therapeutic vectors for gene-based antitumor therapy