Gaurav Sharma

Bio: Gaurav Sharma is an academic researcher from Shenzhen University. The author has contributed to research in topics: Medicine & Photocatalysis. The author has an hindex of 82, co-authored 1244 publications receiving 31482 citations. Previous affiliations of Gaurav Sharma include Northeastern University & D. E. Shaw & Co..

Preclinical Safety Assessment of Chemically Cross-Linked Modified Mandua Starch: Acute and Sub-Acute Oral Toxicity Studies in Swiss Albino Mice

Abstract: In the present era, 28 days of repeated-dose-toxicity study following the Organization for Economic Cooperation and Development (OECD) guidelines 407 is compulsory for every drug to go through phase 1 clinical trials. The increasing demand for high-resistant starch containing nutraceuticals and the applicability of modified starch in development of targeted drug delivery inspired us to investigate the toxic profile of mandua starch chemically cross-linked by epichlorohydrin and compare it with alkali-isolated starch in healthy adult Swiss albino mice, which can be the first step for exploring the use of epichlorohydrin-cross-linked mandua starch (ECC-MS) as a pharmaceutical excipient. Histopathological examinations of the kidney and liver did not expose noteworthy abnormalities in the treated mice. There were no clinical and mortality symptoms of toxicity observed during the repeated-dose-toxicity study. The oral consumption of ECC-MS did not pose any harm as it was neither lethal nor had any harmful hematological, biochemical, psychological, anatomical, and behavioral effects. The use of ECC-MS and alkali-isolated mandua starch (AMS) was found safe at a dose of 2000 mg/kg body weight in the acute toxicity study and at doses of 2000, 1500, and 1000 mg/kg body weight in the sub-acute toxicity study as no detrimental effects were observed after oral administration in mice for 14 and 28 days, respectively.

Application Of High Capacity Data Hiding In Halftone Images

Abstract: We consider applications of our recently proposed method for hiding digital data in halftone images via dot orientation modulation. As compared to prior halftone image watermarking techniques, the method allows for automated extraction of the data and relatively high capacity. These characteristics enable several new applications that we highlight in this paper. By quantifying the effective error free operational rates obtained with suitable error correction codes in our experimental evaluations, we identify the rate constraints on feasible applications. In particular, our estimates indicate that the method can be utilized for a) embedding thumbnails of images for validation and authentication, b) embedding speech in printed images in order to improve accessibility for the visually impaired, and c) embedding textfor carrying meta-data pertaining to the image in the printed image itself (e.g. biography in portrait). We demonstrate a working prototype illustrating the applications.

Channel-wise barcodes for color display applications

Abstract: We present a channel-wise (CW) framework for data embedding in display images using barcodes. Data are embedded in one or more channels of the color image encoded as a monochrome barcode pattern and extracted from the corresponding channels by the decoder. We highlight two advantageous schemes, realized in the proposed framework: red, green, blue CW barcodes (RGB-CWBs), and blue channel image-barcodes (BC-IBs). Compared with a conventional monochrome black and white barcode BW-B with the same spatial footprint, RGB-CWBs utilize the three channels of color image more effectively and enable a three-fold increase in data rate, whereas BC-IBs significantly reduce the embedding distortion by exploiting the reduced sensitivity of the visual system to spatial detail in blue colors. For RGB-CWBs, we develop an effective framework for the cancellation of cross-channel interference between the display and capture channels using a model for the display and capture processes and for the ambient illumination. Model parameters required for interference cancellation (IC) are learned on-the-fly using either expectation-maximization or through suitable design of the synchronization patterns as “pilot-blocks.” Extensive experiments over multiple display and capture devices validate the advantages of the framework: RGB-CWBs (with IC) and the BC-IBs offer bit error rates comparable to their monochrome counterparts while providing either a three-fold increase in data rate or a significant reduction in distortion, respectively.

Optimum Watermark Design by Vector Space Projections

Abstract: We introduce an optimum watermark embedding technique that satisfies common watermarking requirements such as visual fidelity, sufficient embedding rate, robustness against noise and tolerance to benign signal processing, while optimizing one of these requirements. The algorithm distinguishes itself from other watermark optimization techniques in its flexibility for incorporating constraints and in assuring convergence to the globally optimum point when all constraints are convex. The proposed scheme is a natural extension of set-theoretic watermark design and inherits all the advantages of it. A watermarked image is first obtained by POCS, then optimum watermarked image is determined by an iterative search procedure based on a simple bi-section method. Experimental results are presented to illustrate the effectiveness of the method.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

SPAdes, a new genome assembly algorithm and its applications to single-cell sequencing ( 7th Annual SFAF Meeting, 2012)

Abstract: The lion's share of bacteria in various environments cannot be cloned in the laboratory and thus cannot be sequenced using existing technologies. A major goal of single-cell genomics is to complement gene-centric metagenomic data with whole-genome assemblies of uncultivated organisms. Assembly of single-cell data is challenging because of highly non-uniform read coverage as well as elevated levels of sequencing errors and chimeric reads. We describe SPAdes, a new assembler for both single-cell and standard (multicell) assembly, and demonstrate that it improves on the recently released E+V-SC assembler (specialized for single-cell data) and on popular assemblers Velvet and SoapDeNovo (for multicell data). SPAdes generates single-cell assemblies, providing information about genomes of uncultivatable bacteria that vastly exceeds what may be obtained via traditional metagenomics studies. SPAdes is available online ( http://bioinf.spbau.ru/spades ). It is distributed as open source software.