CODING SCRIPT TO AVOID DATA CORRUPTION TO PROTECT MEMORIES

The primary challenge is the fact that individual’s codes should minimize the delay and area penalty. One of the codes which have been considered for memory protection is Reed-Solomon (RS) codes. This limits using ECCs in high-speed recollections. It has brought to using simple codes for example single error correction double error recognition (SEC-DED) codes. However, as technology scales multiple cell upsets (MCUs) be common and limit using SEC-DED codes unless of course they're coupled with interleaving. To prevent data corruption, error correction codes (ECCs) are broadly accustomed to safeguard recollections. ECCs introduce a delay penalty in being able to access the information as encoding or deciphering needs to be carried out. An identical issue happens in some kinds of recollections like DRAM which are typically arranged in modules made up of several products. In individual’s modules, the security against a tool failure instead of isolated bit errors can also be desirable. In individual’s cases, one option is by using more complex ECCs that may correct multiple bit errors. These codes derive from non-binary symbols and for that reason can correct multiple bit errors. Within this paper, single symbol error correction codes according to Reed-Solomon codes that may be implemented with low delay are suggested and evaluated. The outcomes show that they'll be implemented having a substantially lower delay than traditional single error correction RS codes

STABILITY-INDICATING VALIDATED REVERSED PHASE-HIGH PERFORMANCE LIQUID CHROMATOGRAPHY METHOD FOR SIMULTANEOUS DETERMINATION OF COBICISTAT AND ATAZANAVIR SULFATE IN BULK AND PHARMACEUTICAL DOSAGE FORM

ABSTRACTObjective: A simple, rapid, precise, accurate, and economical stability-indicating reversed phase-high performance liquid assay method was developedand validated for simultaneous estimation of cobicistat (COB) and atazanavir (ATV) sulfate in bulk drugs and their combined commercial tablets.Methods: The method has shown adequate separation of COB and ATV from their degradation products. Separation was achieved on a LunaCN (250 mm × 4.6 mm, 5 μm column at a detection wavelength of 239 nm) using a mobile phase consists of o-phthaldialdeyde (Ph2.5) IX buffer,acetonitrile, and methanol in the ratio of 40:40:20 in an isocratic elution mode at a flow rate of 1 ml/min. Results: The retention times for COB and ATV sulfate were found to be 3.606 and 6.113 min, respectively. COB and ATV sulfate, their combinationdrug product was subjected to acid, base, neutral hydrolysis, thermal, and photolytic stress conditions. Thus, stressed samples were analyzed by theproposed analytical method. Validation of the proposed analytical method was carried out as per ICH guidelines Q2R1. Quantitation was achievedwith UV detection at 239 nm based on peak area with linear calibration curves at concentration ranges 50-600 μg/ml for COB and 100-1200 μg/ml forATV sulfate (R2 = 0.999 for both drugs). The limits of detection were 0.25 μg/ml and 0.5 μg/ml for COB and ATV sulfate, respectively. Conclusion: The method was found to be specific and stability indicating as no interfering peaks of degradants and excipients were observed. Theproposed method is hence suitable for application in quality-control laboratories for quantitative analysis of both the drugs individually and incombination dosage forms since it is simple and rapid with good accuracy and precision.Keywords: Stability-indicating assay, Reversed phase-high performance liquid, Cobicistat, Atazanavir sulfate, Forced degradation studies

The giant lobes of Centaurus A observed at 118 MHz with the Murchison Widefield Array

We present new wide-field observations of Centaurus A (Cen A) and the surrounding region at 118MHz with the Murchison Widefield Array (MWA) 32-tile prototype, with which we investigate the spectral-index distribution of Cen A's giant radio lobes.We compa

The Murchison Widefield Array Transients Survey (MWATS). A search for low frequency variability in a bright Southern hemisphere sample

We report on a search for low-frequency radio variability in 944 bright (> 4Jy at 154 MHz) unresolved, extragalactic radio sources monitored monthly for several years with the Murchison Widefield Array. In the majority of sources we find very low levels of variability with typical modulation indices < 5%. We detect 15 candidate low frequency variables that show significant long term variability (>2.8 years) with time-averaged modulation indices M = 3.1 - 7.1%. With 7/15 of these variable sources having peaked spectral energy distributions, and only 5.7% of the overall sample having peaked spectra, we find an increase in the prevalence of variability in this spectral class. We conclude that the variability seen in this survey is most probably a consequence of refractive interstellar scintillation and that these objects must have the majority of their flux density contained within angular diameters less than 50 milli-arcsec (which we support with multi-wavelength data). At 154 MHz we demonstrate that interstellar scintillation time-scales become long (~decades) and have low modulation indices, whilst synchrotron driven variability can only produce dynamic changes on time-scales of hundreds of years, with flux density changes less than one milli-jansky (without relativistic boosting). From this work we infer that the low frequency extra-galactic southern sky, as seen by SKA-Low, will be non-variable on time-scales shorter than one year.Comment: 19 pages, 11 figure

SIMULTANEOUS OBSERVATIONS of GIANT PULSES from the CRAB PULSAR, with the MURCHISON WIDEFIELD ARRAY and PARKES RADIO TELESCOPE: IMPLICATIONS for the GIANT PULSE EMISSION MECHANISM

We report on observations of giant pulses from the Crab pulsar performed simultaneously with the Parkes radio telescope and the incoherent combination of the Murchison Widefield Array (MWA) antenna tiles. The observations were performed over a duration of approximately one hour at a center frequency of 1382 MHz with 340 MHz bandwidth at Parkes, and at a center frequency of 193 MHz with 15 MHz bandwidth at the MWA. Our analysis has led to the detection of 55 giant pulses at the MWA and 2075 at Parkes above a threshold of 3.5σ and 6.5σ, respectively. We detected 51% of the MWA giant pulses at the Parkes radio telescope, with spectral indices in the range of -3.6 > α > -4.9 (Sv ∝ vα). We present a Monte Carlo analysis supporting the conjecture that the giant pulse emission in the Crab is intrinsically broadband, the less than 100% correlation being due to the relative sensitivities of the two instruments and the width of the spectral index distribution. Our observations are consistent with the hypothesis that the spectral index of giant pulses is drawn from normal distribution of standard deviation 0.6, but with a mean that displays an evolution with frequency from -3.00 at 1382 MHz, to -2.85 at 192 MHz

Interferometric imaging with the 32 element Murchison Wide-field Array

The Murchison Wide-field Array (MWA) is a low frequency radio telescope, currently under construction, intended to search for the spectral signature of the epoch of re-ionisation (EOR) and to probe the structure of the solar corona. Sited in Western Australia, the full MWA will comprise 8192 dipoles grouped into 512 tiles, and be capable of imaging the sky south of 40 degree declination, from 80 MHz to 300 MHz with an instantaneous field of view that is tens of degrees wide and a resolution of a few arcminutes. A 32-station prototype of the MWA has been recently commissioned and a set of observations taken that exercise the whole acquisition and processing pipeline. We present Stokes I, Q, and U images from two ~4 hour integrations of a field 20 degrees wide centered on Pictoris A. These images demonstrate the capacity and stability of a real-time calibration and imaging technique employing the weighted addition of warped snapshots to counter extreme wide field imaging distortions.Comment: Accepted for publication in PASP. This is the draft before journal typesetting corrections and proofs so does contain formatting and journal style errors, also has with lower quality figures for space requirement

A new layout optimization technique for interferometric arrays, applied to the MWA

Antenna layout is an important design consideration for radio interferometers because it determines the quality of the snapshot point spread function (PSF, or array beam). This is particularly true for experiments targeting the 21 cm Epoch of Reionization signal as the quality of the foreground subtraction depends directly on the spatial dynamic range and thus the smoothness of the baseline distribution. Nearly all sites have constraints on where antennas can be placed---even at the remote Australian location of the MWA (Murchison Widefield Array) there are rock outcrops, flood zones, heritages areas, emergency runways and trees. These exclusion areas can introduce spatial structure into the baseline distribution that enhance the PSF sidelobes and reduce the angular dynamic range. In this paper we present a new method of constrained antenna placement that reduces the spatial structure in the baseline distribution. This method not only outperforms random placement algorithms that avoid exclusion zones, but surprisingly outperforms random placement algorithms without constraints to provide what we believe are the smoothest constrained baseline distributions developed to date. We use our new algorithm to determine antenna placements for the originally planned MWA, and present the antenna locations, baseline distribution, and snapshot PSF for this array choice.Comment: 12 pages, 6 figures, 1 table. Accepted for publication in MNRA

WSClean : an implementation of a fast, generic wide-field imager for radio astronomy

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.Astronomical widefield imaging of interferometric radio data is computationally expensive, especially for the large data volumes created by modern non-coplanar many-element arrays. We present a new widefield interferometric imager that uses the w-stacking algorithm and can make use of the w-snapshot algorithm. The performance dependencies of CASA's w-projection and our new imager are analysed and analytical functions are derived that describe the required computing cost for both imagers. On data from the Murchison Widefield Array, we find our new method to be an order of magnitude faster than w-projection, as well as being capable of full-sky imaging at full resolution and with correct polarisation correction. We predict the computing costs for several other arrays and estimate that our imager is a factor of 2-12 faster, depending on the array configuration. We estimate the computing cost for imaging the low-frequency Square-Kilometre Array observations to be 60 PetaFLOPS with current techniques. We find that combining w-stacking with the w-snapshot algorithm does not significantly improve computing requirements over pure w-stacking. The source code of our new imager is publicly released.Peer reviewedFinal Published versio

A study of fundamental limitations to statistical detection of redshifted H i from the epoch of reionization

In this paper, we explore for the first time the relative magnitudes of three fundamental sources of uncertainty, namely, foreground contamination, thermal noise, and sample variance, in detecting the H I power spectrum from the epoch of reionization (Eo