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On the Conjectures on Optimality of Index Codes from Interlinked Cycle Cover Scheme
No full textThe interlinked cycle (IC) structure, that generalizes cycles and cliques was defined by Thapa, Ong and Johnson. Interlinked-cycle-cover (ICC) scheme that leverages IC structures in digraphs to construct scalar linear index codes was proposed. Thapa et. al. conjectured that for any IC structure, the ICC scheme is optimal. It was also conjectured that for any digraph, the ICC scheme performs at least as well as the partial-clique-cover scheme. In this paper, we disprove both the conjectures. We also show that for a specific class of symmetric index coding problems, the performance of ICC scheme is equal to that of the partial-clique-cover scheme
Optimal Lossless Source Codes for Timely Updates
No full textA transmitter observing a sequence of independent and identically distributed random variables seeks to keep a receiver updated about its latest observations. The receiver need not be apprised about each symbol seen by the transmitter, but needs to output a symbol at each time instant t. If at time t the receiver outputs the symbol seen by the transmitter at time U(t) <= t, the age of information at the receiver at time t is t - U(t). We study the design of lossless source codes that enable transmission with minimum average age at the receiver. We show that the asymptotic minimum average age can be attained (up to a constant bits gap) by Shannon codes for a tilted version of the original pmf generating the symbols, which can be computed easily by solving an optimization problem. Underlying our construction for minimum average age codes is a new variational formula for integer moments of random variables, which may be of independent interest
Extra Samples can Reduce the Communication for Independence Testing
No full textTwo parties observing sequences of bits want to determine if their bits were generated independently or not. To that end, the first party communicates to the second. A simple communication scheme involves taking as few sample bits as determined by the sample complexity of independence testing and sending it to the second party. But is there a scheme that uses fewer bits of communication than the sample complexity, perhaps by observing more sample bits? We show that the answer to this question is in the affirmative when the joint distribution is a binary symmetric source. More generally, for any given joint distribution, we present a distributed independence test that uses linear correlation between functions of the observed random variables. Furthermore, we provide lower bounds for the general setting that use hypercontractivity and reverse hypercontractivity to obtain a measure change bound between the joint and the independent distributions. The resulting bounds are tight for both a binary symmetric source and a Gaussian symmetric source
Inverse Simulation for Gas Turbine Engine Control through Differential Algebraic Inequality Formulation
No full textModern day gas turbines are prime movers in land, air and sea. They have stringent performance requirements to meet the complex mission objectives. Optimal control strategies can help them meet their performance objectives more efficiently. A novel inverse simulation method for optimal control and system analysis studies using Differential Algebraic Equality/Inequality (DAE/DAI) technique is brought out in this paper with a case study. The gas turbine model together with safety constraints and performance specifications is represented as a high index DAI/DAE system. The solution for this DAE/DAI system is obtained using a new numerical approach that is capable of handling both equality and inequality constraints on system dynamics. The algorithm involves direct numerical integration of a DAI formulation in a time stepping manner using Sequential Quadratic Programming (SQP) solver that detects and satisfy active constraints at each time step (mesh point). In this unique approach the model and the constraints are always solved together. The method ensures stable solution at each time step, local minimum at each iteration of simulation and provides a regularised basis to the solver. Compared to other existing computationally intensive techniques in usage, this approach is easy, ensures continuous constraint satisfaction and provides a viable option for Model Predictive Control (MPC) of gas turbine engines
Exfoliated graphite containing metal oxides for high-performance pseudocapacitor applications
No full textWe report a rapid and efficient chemical synthesis of exfoliated graphite (EG) containing metal oxides such as manganese oxide (MnO and Mn3O4) and copper oxide (Cu2O) using microwave irradiation technique. The size of the manganese oxide particles is in the range of 50-800 nm, whereas, copper oxide is in the range of 30nm-2 mu m. Four types of EG materials (EG1, EG2, EG3 and EG4) were prepared to identify best electrode. Among all, EG4 electrode shows high performance for pseudocapacitors. The specific capacitance obtained was 335.9 (+/- 12.4) F/g at a current density of 0.5 A/g within a potential window of -0.3-0.8 V under aqueous 1M Na2SO4 electrolyte solution. It exhibits good rate capability (76% retention when the current density increases from 0.5 to 10 A g(-1)), and long-term cycling stability, with 93.4% (+/- 0.7) capacitance retention after 3000 cycles. Thus, the EG containing various metal oxides can present a promising potential candidate for pseudocapacitors and other commercial applications. (C) 2018 Elsevier B.V. All rights reserved
Absence of Receptor Guanylyl Cyclase C Enhances Ileal Damage and Reduces Cytokine and Antimicrobial Peptide Production during Oral Salmonella enterica Serovar Typhimurium Infection (vol 86, e00799-17, 2018)
No full textNontyphoidal Salmonella disease contributes toward significant morbidity and mortality across the world. Host factors, including gamma interferon, tumor necrosis factor alpha, and gut microbiota, significantly influence the outcome of Salmonella pathogenesis. However, the entire repertoire of host protective mechanisms contributing to Salmonella pathogenicity is not completely appreciated. Here, we investigated the roles of receptor guanylyl cyclase C (GC-C), which is predominantly expressed in the intestine and regulates intestinal cell proliferation and fluid-ion homeostasis. Mice deficient in GC-C (Gucy2c-/-) displayed accelerated mortality compared with that for wild-type mice following infection via the oral route, even though both groups possessed comparable systemic Salmonella infection burdens. Survival following intraperitoneal infection remained similar in both groups, indicating that GC-C offered protection via a gut-mediated response. The serum cortisol level was higher in Gucy2c-/- mice than wild-type (Gucy2c+/+) mice, and an increase in infection-induced thymic atrophy with a loss of immature CD4+ CD8+ double-positive thymocytes was observed. Accelerated and enhanced damage in the ileum, including submucosal edema, epithelial cell damage, focal tufting, and distortion of the villus architecture, was seen in Gucy2c-/- mice concomitantly with a larger number of ileal tissue-associated bacteria. Transcription of key mediators of Salmonella-induced inflammation (interleukin-22/Reg3β) was altered in Gucy2c-/- mice in comparison to that in Gucy2c+/+ mice. A reduction in fecal lactobacilli, which are protective against Salmonella infection, was observed in Gucy2c-/- mice. Gucy2c-/- mice cohoused with wild-type mice continued to show reduced amounts of lactobacilli and increased susceptibility to infection. Our study, therefore, suggests that the receptor GC-C confers a survival advantage during gut-mediated Salmonella enterica serovar Typhimurium pathogenesis, presumably by regulating Salmonella effector mechanisms and maintaining a beneficial microbiome
Deregulated AUF1 Assists BMP-EZH2-Mediated Delayed Wound Healing during Candida albicans Infection
No full textTissue repair is a complex process that necessitates an interplay of cellular processes, now known to be dictated by epigenetics. Intriguingly, macrophages are testimony to a large repertoire of evolving functions in this process. We identified a role for BMP signaling in regulating macrophage responses to Candida albicans infection during wound repair in a murine model. In this study, the RNA binding protein, AU-rich element-binding factor 1, was posttranslationally destabilized to bring about ubiquitin ligase, NEDD4-directed activation of BMP signaling. Concomitantly, PI3K/PKC delta mobilized the rapid phosphorylation of BMP-responsive Smad1/5/8. Activated BMP pathway orchestrated the elevated recruitment of EZH2 at promoters of genes assisting timely wound closure. In vivo, the repressive H3K27 trimethylation was observed to persist, accompanied by a robust upregulation of BMP pathway upon infection with C. albicans, culminating in delayed wound healing. Altogether, we uncovered the signaling networks coordinated by fungal colonies that are now increasingly associated with the infected wound microbiome, resulting in altered wound fate
Swift Combustion Synthesis of PbLi2Ti6O14 Anode for Lithium-Ion Batteries: Diffusional and Electrochemical Investigation
No full textLead lithium titanate (PbLi2Ti6O14) was synthesized by combustion route restricting the annealing at 900 degrees C to just 1 minute. Rietveld analysis confirmed orthorhombic (Cmca) product phase with an average particle size similar to 200 nm and surface area of 2 m(2)/g forming secondary porous particles. From bond valence site energy (BVSE) calculations, 1 D ionic conduction was found along c axis with low activation energy (0.23 eV). AC conductivity analysis revealed a bulk conductivity of 2 x 10(-7) S. cm(-1) at room temperature and 1 x 10(-4) S. cm(-1) at 200 degrees C with a switch from extrinsic 1D to intrinsic 2D mechanism at 150. C. Li + diffusion coefficient was calculated to be in the order of 10(-12) cm(2). s(-1). More than 4 lithium (per f. u.) could be reversibly (de) inserted delivering capacity over 160 mAh/g with good cycling retention over 1000 cycles. With a feasible rapid synthesis, good diffusional and electrochemical behavior especially high rate capability, PbLi2Ti6O14 can act as a safe 1.35 V anode for rechargeable Li-ion batteries. (c) The Author(s) 2018. Published by ECS
IMAGE DENOISING FOR IMAGE RETRIEVAL BY CASCADING A DEEP QUALITY ASSESSMENT NETWORK
No full textImage denoising algorithms have evolved to optimize image quality as measured according to human visual perception. However, image denoising to maximize the success of computer vision algorithms operating on the denoised image has been much less investigated. We consider the problem of image denoising for Gaussian noise with respect to the specific application of image retrieval from a dataset. We define the notion of image quality as determined by the success of image retrieval and design a deep convolutional neural network (CNN) to predict this quality. This network is then cascaded with a deep CNN designed for image denoising, allowing for optimization of the denoising CNN to maximize retrieval performance. This framework allows us to couple denoising to the retrieval problem. We show through experiments on noisy images of the Oxford and Paris buildings datasets that such an approach yields improved mean average precision when compared to using denoising methods that are oblivious to the task of image retrieval
A NOTE ON LINEAR PRESERVERS OF SEMIPOSITIVE AND MINIMALLY SEMIPOSITIVE MATRICES
No full textSemipositive matrices (matrices that map at least one nonnegative vector to a positive vector) and minimally semipositive matrices (semipositive matrices whose no column-deleted submatrix is semipositive) are well studied in matrix theory. In this short note, the structure of linear maps which preserve the set of all semipositive/minimally semipositive matrices is studied. An open problem is solved, and some ambiguities in the article J. Dorsey, T. Gannon, N. Jacobson, C.R. Johnson and M. Turnansky. Linear preservers of semi-positive matrices. Linear and Multilinear Algebra, 64:1853-1862, 2016.] are clarified