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  1. Buch ; Online: Finite-sample concentration of the empirical relative entropy around its mean

    Agrawal, Rohit

    2022  

    Abstract: In this note, we show that the relative entropy of an empirical distribution of $n$ samples drawn from a set of size $k$ with respect to the true underlying distribution is exponentially concentrated around its expectation, with central moment generating ...

    Abstract In this note, we show that the relative entropy of an empirical distribution of $n$ samples drawn from a set of size $k$ with respect to the true underlying distribution is exponentially concentrated around its expectation, with central moment generating function bounded by that of a gamma distribution with shape $2k$ and rate $n/2$. This improves on recent work of Bhatt and Pensia (arXiv 2021) on the same problem, who showed such a similar bound with an additional polylogarithmic factor of $k$ in the shape, and also confirms a recent conjecture of Mardia et al. (Information and Inference 2020). The proof proceeds by reducing the case $k>3$ of the multinomial distribution to the simpler case $k=2$ of the binomial, for which the desired bound follows from standard results on the concentration of the binomial.
    Schlagwörter Mathematics - Statistics Theory ; Computer Science - Information Theory ; Mathematics - Probability
    Erscheinungsdatum 2022-03-01
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    Dokumenttyp Buch ; Online
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  2. Artikel: Sustainable material selection for additive manufacturing technologies: A critical analysis of rank reversal approach

    Agrawal, Rohit

    Journal of cleaner production. 2021 May 10, v. 296

    2021  

    Abstract: The world is moving towards a situation where resource scarcity leads to increased material cost, and the government is bound to dispose of heavy wastes generated by the growing population. Additive Manufacturing (AM) has bought a significant revolution ... ...

    Abstract The world is moving towards a situation where resource scarcity leads to increased material cost, and the government is bound to dispose of heavy wastes generated by the growing population. Additive Manufacturing (AM) has bought a significant revolution in the current manufacturing processes. AM can fabricate complex and intricate shapes with ease. Material selection is an essential aspect in AM as a wide range of compatible materials available for AM. Appropriate material selection is necessary for cleaner production and sustainable development. Sustainable material selection considering various material properties and varied criteria can be effectively managed by Multi-Criteria Decision Making (MCDM) approach. However, several MCDM methods have a rank reversal problem, in which the rank of alternatives got changed when an alternative is added or removed from all considered alternatives. In this regard, this work presents a sustainable material selection of AM technologies. Sustainable material selection has been made for 3 a.m. technologies, namely Fused Deposition Modelling (FDM), Selective Laser Sintering (SLS), and Stereolithography (SLA). Four MCDM techniques have been used to analyze and compare AM materials, namely SAW (Simple Additive Weighting), MOORA (Multi-Objective Optimization based on Ratio Analysis), TOPSIS (Technique for order performance by similarity to ideal solution), and VIKOR (Vlsekriterijumska Optimizacija I Kompromisno Resenje). Rank reversal problems associated with MCDM methods are also highlighted in the material selection stage. The results reveal that ‘TPU Elastomer’, ‘Accura HPC′, and ‘Duraform EX′ are identified as the best material for FDM, SLA, and SLS based AM technologies. Further, practical and research implications have been derived based on the study to help industrial practitioners, researchers, and decision-makers for the selection of the best materials in the product development stage to support cleaner production.
    Schlagwörter additives ; cleaning ; developmental stages ; journals ; lasers ; manufacturing ; materials ; models ; multi-criteria decision making ; product development ; shape ; solutions ; sustainable development ; wastes ; weight
    Sprache Englisch
    Erscheinungsverlauf 2021-0510
    Erscheinungsort Elsevier Ltd
    Dokumenttyp Artikel
    ISSN 0959-6526
    DOI 10.1016/j.jclepro.2021.126500
    Datenquelle NAL Katalog (AGRICOLA)

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  3. Buch ; Online: $\ell_1$SABMIS

    Agrawal, Rohit

    $\ell_1$-minimization and sparse approximation based blind multi-image steganography scheme

    2020  

    Abstract: Steganography plays a vital role in achieving secret data security by embedding it into cover media. The cover media and the secret data can be text or multimedia, such as images, videos, etc. In this paper, we propose a novel $\ell_1$-minimization and ... ...

    Abstract Steganography plays a vital role in achieving secret data security by embedding it into cover media. The cover media and the secret data can be text or multimedia, such as images, videos, etc. In this paper, we propose a novel $\ell_1$-minimization and sparse approximation based blind multi-image steganography scheme, termed $\ell_1$SABMIS. By using $\ell_1$SABMIS, multiple secret images can be hidden in a single cover image. In $\ell_1$SABMIS, we sampled cover image into four sub-images, sparsify each sub-image block-wise, and then obtain linear measurements. Next, we obtain DCT (Discrete Cosine Transform) coefficients of the secret images and then embed them into the cover image\textquotesingle s linear measurements. We perform experiments on several standard gray-scale images, and evaluate embedding capacity, PSNR (peak signal-to-noise ratio) value, mean SSIM (structural similarity) index, NCC (normalized cross-correlation) coefficient, NAE (normalized absolute error), and entropy. The value of these assessment metrics indicates that $\ell_1$SABMIS outperforms similar existing steganography schemes. That is, we successfully hide more than two secret images in a single cover image without degrading the cover image significantly. Also, the extracted secret images preserve good visual quality, and $\ell_1$SABMIS is resistant to steganographic attack.
    Schlagwörter Computer Science - Multimedia
    Thema/Rubrik (Code) 518
    Erscheinungsdatum 2020-07-09
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    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  4. Artikel ; Online: EUS-guided gallbladder drainage in a patient with Billroth II reconstruction.

    Agrawal, Rohit / Hassan, Ahmad M / Villa, Edward

    VideoGIE : an official video journal of the American Society for Gastrointestinal Endoscopy

    2023  Band 8, Heft 4, Seite(n) 155–157

    Abstract: Video 1EUS-guided gallbladder drainage in a patient with Billroth II gastrojejunostomy. ...

    Abstract Video 1EUS-guided gallbladder drainage in a patient with Billroth II gastrojejunostomy.
    Sprache Englisch
    Erscheinungsdatum 2023-03-15
    Erscheinungsland United States
    Dokumenttyp Journal Article
    ISSN 2468-4481
    ISSN (online) 2468-4481
    DOI 10.1016/j.vgie.2022.12.010
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  5. Buch ; Online: Samplers and Extractors for Unbounded Functions

    Agrawal, Rohit

    2019  

    Abstract: Blasiok (SODA'18) recently introduced the notion of a subgaussian sampler, defined as an averaging sampler for approximating the mean of functions $f:\{0,1\}^m \to \mathbb{R}$ such that $f(U_m)$ has subgaussian tails, and asked for explicit constructions. ...

    Abstract Blasiok (SODA'18) recently introduced the notion of a subgaussian sampler, defined as an averaging sampler for approximating the mean of functions $f:\{0,1\}^m \to \mathbb{R}$ such that $f(U_m)$ has subgaussian tails, and asked for explicit constructions. In this work, we give the first explicit constructions of subgaussian samplers (and in fact averaging samplers for the broader class of subexponential functions) that match the best-known constructions of averaging samplers for $[0,1]$-bounded functions in the regime of parameters where the approximation error $\varepsilon$ and failure probability $\delta$ are subconstant. Our constructions are established via an extension of the standard notion of randomness extractor (Nisan and Zuckerman, JCSS'96) where the error is measured by an arbitrary divergence rather than total variation distance, and a generalization of Zuckerman's equivalence (Random Struct. Alg.'97) between extractors and samplers. We believe that the framework we develop, and specifically the notion of an extractor for the Kullback-Leibler (KL) divergence, are of independent interest. In particular, KL-extractors are stronger than both standard extractors and subgaussian samplers, but we show that they exist with essentially the same parameters (constructively and non-constructively) as standard extractors.

    Comment: An extended abstract appeared in the proceedings of RANDOM 2019
    Schlagwörter Computer Science - Computational Complexity ; Computer Science - Data Structures and Algorithms
    Erscheinungsdatum 2019-04-17
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    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  6. Buch ; Online: Finite-Sample Concentration of the Multinomial in Relative Entropy

    Agrawal, Rohit

    2019  

    Abstract: We show that the moment generating function of the Kullback-Leibler divergence (relative entropy) between the empirical distribution of $n$ independent samples from a distribution $P$ over a finite alphabet of size $k$ (i.e. a multinomial distribution) ... ...

    Abstract We show that the moment generating function of the Kullback-Leibler divergence (relative entropy) between the empirical distribution of $n$ independent samples from a distribution $P$ over a finite alphabet of size $k$ (i.e. a multinomial distribution) and $P$ itself is no more than that of a gamma distribution with shape $k - 1$ and rate $n$. The resulting exponential concentration inequality becomes meaningful (less than 1) when the divergence $\varepsilon$ is larger than $(k-1)/n$, whereas the standard method of types bound requires $\varepsilon > \frac{1}{n} \cdot \log{\binom{n+k-1}{k-1}} \geq (k-1)/n \cdot \log(1 + n/(k-1))$, thus saving a factor of order $\log(n/k)$ in the standard regime of parameters where $n\gg k$. As a consequence, we also obtain finite-sample bounds on all the moments of the empirical divergence (equivalently, the discrete likelihood-ratio statistic), which are within constant factors (depending on the moment) of their asymptotic values. Our proof proceeds via a simple reduction to the case $k = 2$ of a binary alphabet (i.e. a binomial distribution), and has the property that improvements in the case of $k = 2$ directly translate to improvements for general $k$. In particular, we conjecture a bound on the binomial moment generating function that would almost close the quadratic gap between our finite-sample bound and the asymptotic moment generating function bound from Wilks' theorem (which does not hold for finite samples).
    Schlagwörter Computer Science - Information Theory ; Mathematics - Probability ; Mathematics - Statistics Theory
    Thema/Rubrik (Code) 519
    Erscheinungsdatum 2019-04-03
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    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  7. Buch ; Online: Coin Theorems and the Fourier Expansion

    Agrawal, Rohit

    2019  

    Abstract: In this note we compare two measures of the complexity of a class $\mathcal F$ of Boolean functions studied in (unconditional) pseudorandomness: $\mathcal F$'s ability to distinguish between biased and uniform coins (the coin problem), and the norms of ... ...

    Abstract In this note we compare two measures of the complexity of a class $\mathcal F$ of Boolean functions studied in (unconditional) pseudorandomness: $\mathcal F$'s ability to distinguish between biased and uniform coins (the coin problem), and the norms of the different levels of the Fourier expansion of functions in $\mathcal F$ (the Fourier growth). We show that for coins with low bias $\varepsilon = o(1/n)$, a function's distinguishing advantage in the coin problem is essentially equivalent to $\varepsilon$ times the sum of its level $1$ Fourier coefficients, which in particular shows that known level $1$ and total influence bounds for some classes of interest (such as constant-width read-once branching programs) in fact follow as a black-box from the corresponding coin theorems, thereby simplifying the proofs of some known results in the literature. For higher levels, it is well-known that Fourier growth bounds on all levels of the Fourier spectrum imply coin theorems, even for large $\varepsilon$, and we discuss here the possibility of a converse.

    Comment: 15 pages, 1 figure
    Schlagwörter Computer Science - Computational Complexity
    Thema/Rubrik (Code) 511
    Erscheinungsdatum 2019-06-09
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    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  8. Artikel ; Online: Green energy innovation initiatives for environmental sustainability: current state and future research directions.

    Dhayal, Karambir Singh / Agrawal, Shruti / Agrawal, Rohit / Kumar, Anil / Giri, Arun Kumar

    Environmental science and pollution research international

    2024  

    Abstract: Worldwide, all countries have been facing the crisis of climate change problem. They have been addressing this issue by focusing on implementing green energy innovation initiatives and promoting a sustainable future through environmental sustainability. ... ...

    Abstract Worldwide, all countries have been facing the crisis of climate change problem. They have been addressing this issue by focusing on implementing green energy innovation initiatives and promoting a sustainable future through environmental sustainability. In this research study, we focus on examining the role of green finance through green energy innovations, which are taking place in several sectors across different regions to promote environmental sustainability. The study has analysed 152 articles on this research domain through a systematic literature review to understand the present state of existing knowledge. The current study examines the Scopus-indexed research articles from the time period 2002 to 2023. Six emerging themes have been examined to understand their development and the potential impact of green initiatives for environmental sustainability. Various institutional theories have been explored to understand their association with the investigated research area. The paper has discussed multiple challenges that need to be addressed for the speedy implementation of green innovations. Finally, future research questions have been proposed based on the findings from the extant literature and the existing research gaps.
    Sprache Englisch
    Erscheinungsdatum 2024-04-24
    Erscheinungsland Germany
    Dokumenttyp Journal Article ; Review
    ZDB-ID 1178791-0
    ISSN 1614-7499 ; 0944-1344
    ISSN (online) 1614-7499
    ISSN 0944-1344
    DOI 10.1007/s11356-024-33286-x
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  9. Buch ; Online: CSIS

    Agrawal, Rohit / Ahuja, Kapil

    compressed sensing-based enhanced-embedding capacity image steganography scheme

    2021  

    Abstract: Image steganography plays a vital role in securing secret data by embedding it in the cover images. Usually, these images are communicated in a compressed format. Existing techniques achieve this but have low embedding capacity. Enhancing this capacity ... ...

    Abstract Image steganography plays a vital role in securing secret data by embedding it in the cover images. Usually, these images are communicated in a compressed format. Existing techniques achieve this but have low embedding capacity. Enhancing this capacity causes a deterioration in the visual quality of the stego-image. Hence, our goal here is to enhance the embedding capacity while preserving the visual quality of the stego-image. We also intend to ensure that our scheme is resistant to steganalysis attacks. This paper proposes a Compressed Sensing Image Steganography (CSIS) scheme to achieve our goal while embedding binary data in images. The novelty of our scheme is the combination of three components in attaining the above-listed goals. First, we use compressed sensing to sparsify cover image block-wise, obtain its linear measurements, and then uniquely select permissible measurements. Further, before embedding the secret data, we encrypt it using the Data Encryption Standard (DES) algorithm, and finally, we embed two bits of encrypted data into each permissible measurement. Second, we propose a novel data extraction technique, which is lossless and completely recovers our secret data. Third, for the reconstruction of the stego-image, we use the least absolute shrinkage and selection operator (LASSO) for the resultant optimization problem. We perform experiments on several standard grayscale images and a color image, and evaluate embedding capacity, PSNR value, mean SSIM index, NCC coefficients, and entropy. We achieve 1.53 times more embedding capacity as compared to the most recent scheme. We obtain an average of 37.92 dB PSNR value, and average values close to 1 for both the mean SSIM index and the NCC coefficients, which are considered good. Moreover, the entropy of cover images and their corresponding stego-images are nearly the same.

    Comment: 12 pages double-column, 7 tables, and 11 figures
    Schlagwörter Computer Science - Multimedia ; Mathematics - Optimization and Control ; I.4.2 ; I.4.5 ; I.4.9 ; E.3
    Erscheinungsdatum 2021-01-03
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    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  10. Artikel: Ectopic Opening of the Bile Duct Into the Duodenal Bulb: Complications of Biliary Drainage.

    Yang, James / Agrawal, Rohit / Melitas, Constantine / Boulay, Brian / Herren, Josi / Gaba, Ronald / Villa, Edward

    ACG case reports journal

    2023  Band 10, Heft 2, Seite(n) e00973

    Abstract: Ectopic opening of the common bile duct is a rare anatomic variant that is associated with increased risk of complications such as cholangitis, peptic ulcer disease, and even cholangiocarcinoma. Ectopic opening of the common bile duct into the duodenal ... ...

    Abstract Ectopic opening of the common bile duct is a rare anatomic variant that is associated with increased risk of complications such as cholangitis, peptic ulcer disease, and even cholangiocarcinoma. Ectopic opening of the common bile duct into the duodenal bulb is a rare form of ectopic opening of the common bile duct accounting for 0.1%-2.7% of cases of anomalous biliary drainage. Identification of such pathology is important because of its varied presentation and considerable operative and procedural implications. We report a rare case of duodenal bulb opening of the common bile duct in a patient who presented with cholangitis.
    Sprache Englisch
    Erscheinungsdatum 2023-02-16
    Erscheinungsland United States
    Dokumenttyp Case Reports
    ZDB-ID 2814825-3
    ISSN 2326-3253
    ISSN 2326-3253
    DOI 10.14309/crj.0000000000000973
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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