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Periodic interstellar scintillation variations of PSRs J0613-0200 and J0636+5128 associated with the Local Bubble shell

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Science China(Physics,mechanics & Astronomy) 2023年第11期66卷 221-232页

作者： Yulan Liu Robert A.main Joris P.W.Verbiest Ziwei Wu krishnakumar m.ambalappat Jiguang Lu David J.Champion Ismael Cognard Lucas Guillemot Kuo Liu James W.mc Kee Nataliya Porayko Golam.m.Shaifullah Gilles Theureau National Astronomical Observatories Chinese Academy of SciencesBeijing100101China Fakultät für Physik Universität BielefeldBielefeld33501Germany max-Planck-Institut für Radioastronomie Bonn53121Germany Florida Space Institute University of Central FloridaOrlandoFL32826USA Station de radioastronomie de Nançay Observatoire de ParisNançay18330France Laboratoire de Physique et Chimie de l’Environnement et de l’Espace Universitéd’OrléansOrléans45071France E.A.milne Centre for Astrophysics University of HullHullHU67RXUK Centre of Excellence for Data Science Artificial Intelligence and ModellingUniversity of HullHullHU67RXUK Dipartimento di Fisica“G.Occhialini” Universitàdi Milano-BicoccaMilano20126Italy INAF-Osservatorio Astronomico di Cagliari Selargius(CA)09047Italy INFN Sezione di Milano-BicoccaMilano20126Italy

Annual variations of interstellar scintillation can be modelled to constrain parameters of the ionized interstellar *** a pulsar is in a binary system,then investigating the orbital parameters is possible through analysis of the orbital variation of *** observations carried out from 2011 to 2020 by the European Pulsar Timing Array radio telescopes,PSRs J0613-0200and J0636+5128 show strong annual variations in their scintillation velocity,while the former additionally exhibits an orbital *** theory and markov-chain-monte-Carlo methods are used to interpret these periodic *** assume a thin and anisotropic scattering screen model,and discuss the mildly and extremely anisotropic scattering *** J0613-0200is best described by mildly anisotropic scattering,while PSR J0636+5128 exhibits extremely anisotropic *** measure the distance,velocity,and degree of anisotropy of the scattering screen for our two pulsars,finding that scattering screen distances from Earth for PSRs J0613-0200 and J0636+5128 are 316_(-20)^(+28)pc and 262_(-38)^(+96)pc,*** positions of these scattering screens are coincident with the shell of the Local Bubble towards both *** associations add to the growing evidence of the Local Bubble shell as a dominant region of scattering along many sightlines.

关键词： pulsar interstellar scintillation ionized interstellar medium

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Solar active fire clay based hetero-Fenton catalyst over a wide pH range for degradation of Acid Violet 7

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Journal of Environmental Sciences 2012年第3期24卷 529-535页

作者： Inbasekaran muthuvel Balu krishnakumar meenakshisundaram Swaminathan Department of Chemistry Annamalai UniversityAnnamalainagar 608002India.

Fe（III） immobilized fire clay （Fe-FC） was prepared using ferric nitrate by solid state dispersion method and this hetero-Fenton catalyst was applied for the degradation of Acid Violet 7 （AV 7） under natural sunlight. The 26% ferric nitrate loaded fire clay was found to be most efficient. The experimental conditions such as solution pH, H2O2 concentration for efficient degradation of AV 7 have been determined. Unlike Fenton catalyst, Fe-FC is photoactive over a wide pH range of 3-7. This catalyst was found to be stable and reusable. The GC-mS analysis of experimental solutions during irradiation revealed the formation of 2,8-diaminonaphthalene-1,3,6- triol, 8-aminonaphthalene-1,2,3,6-tetrol, 2-aminonaphthalene-1,3,6,8-tetrol and 2-aminobenzene-1,3-diol/5-aminonbenzene-1,3-diol/ 2-aminobenzene-1,4-diol as intermediates. The 26% ferric nitrate loaded fire clay was characterized by XRD, ICP-AES, BET surface area, FT-IR, SEm-EDS and UV-DRS studies.

关键词： hetero-Fenton degradation Acid Violet 7 fire clay wastewater treatment solar light

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Performance Improvement of multiband Triangular microstrip Patch Antenna Using Frequency Selective Surface

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Journal of Shanghai Jiaotong university(Science) 2024年第2期29卷 316-321页

作者： mAHENDRAN krishnakumar GAYATHRI Rajaraman Department of Electronics and Communication Engineering Annamalai UniversityChidambaram 608002India

Today's antennas have to operate in multiple resonant frequencies to satisfy the need of recent advances in communication *** paper presents split ring resonator based triangular multiband antenna whose antenna performance is enhanced with the help of frequency selective surfaces(FSSs).The antenna has multiple resonances at S,C,and X *** array of 4×3 crisscross-shaped unit cells are arranged to form the FSS *** antenna is fed with a microstrip line feeding *** proposed antenna operates at 3.5 GHz,4.1 GHz,5.5GHz,9.4GHz,and 9.8 GHz with a better return loss and *** and measured results yield a good match.

关键词： triangular microstrip antenna split ring resonator frequency selective surface(FSS) metamaterial

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Geographic Drone-based Route Optimization Approach for Emergency Area Ad-Hoc Network

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Computer Systems Science & Engineering 2023年第4期45卷 985-1000页

作者： V.krishnakumar R.Asokan Department of Electronics and Communication Engineering Kongunadu College of Engineering and TechnologyThottiamTrichy621215India

Wireless sensor mobile ad hoc networks have excellent potential in moving and monitoring disaster area networks on real-time *** recent challenges faced in mobile Ad Hoc Networks(mANETs)include scalability,localization,heterogeneous network,self-organization,and self-sufficient *** this background,the current study focuses on specially-designed communication link establishment for high connection stability of wireless mobile sensor networks,especially in disaster area *** protocols focus on location-dependent communications and use networks based on typically-used Internet Protocol(IP)***,IP-based communications have a few limitations such as inefficient bandwidth utilization,high processing,less transfer speeds,and excessive memory *** overcome these challenges,the number of neighbors(Node Density)is minimized and high mobility Nodes(Node Speed)are *** proposed Geographic Drone Based Route Optimization(GDRO)method reduces the entire overhead to a considerable level in an efficient manner and significantly improves the overall performance by identifying the disaster *** drone communicates with anchor node periodically and shares the information to it so as to introduce a drone-based disaster network in an *** routing is a promising approach to enhance the routing efficiency in *** algorithm helps in reaching the anchor(target)node with the help of Geographical Graph-Based mapping(GGm).Global Positioning System(GPS)is enabled on mobile network of the anchor node which regularly broadcasts its location information that helps in finding the *** first step,the node searches for local and remote anticipated Expected Transmission Count(ETX),thereby calculating the estimated *** Signal Strength Indicator(RSSI)results are stored in the local memory of the ***,the node calculates the least remote anticipated ETX,Link Loss Rate,and information to the new location.

关键词： mobile ad hoc networks(mANETs) geographical graph-based mapping(GGm) geographic drone based route optimization data speed anchor node’s

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New approaches to water purification for resource- constrained settings： Production of activated biochar by chemical activation with diammonium hydrogenphosphate

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Frontiers of Chemical Science and Engineering 2018年第1期12卷 194-208页

作者： mohit Nahata Chang Y. Seo Pradeep krishnakumar Johannes Schwank Department of Chemical Engineering University of Michigan-Ann Arbor Ann Arbor MI 48109 USA

A significant portion of the world＇s population does not have access to safe drinking water. This problem is most acute in remote, resource-constrained rural settings in developing countries. Water filtration using activated carbon is one of the important steps in treating con- taminated water. Lignocellulosic biomass is generally available in abundance in such locations, such as the African rain forests. Our work is focused on developing a simple method to synthesize activated biochar from locally available materials. The preparation of activated biochar with diammonium hydrogenphosphate （DAP） as the activating agent is explored under N2 flow and air. The study, carried out with cellulose as a model biomass, provides some insight into the interaction between DAP and biomass, as well as the char forming mechanism. Various characterization techniques such as N2 physisorption, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy are utilized to compare the properties between biochar formed under nitrogen and partial oxidative conditions. At a temperature of 450 ℃, the loading of DAP over cellulose is systematically varied, and its effect on activation is examined. The activated biochar samples are predominantly microporous in the range of concentrations studied. The interaction of DAP with cellulose is investigated and the nature of bonding of the heteroatoms to the carbonaceous matrix is elucidated. The results indicate that the quality of biochar prepared under partial oxidation condition is comparable to that ofbiochar prepared under nitrogen, leading to the possibility of an activated biochar production scheme on a small scale in resource-constrained settings.

关键词： cellulose DAP activation heteroatom,microporous

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molt and reproduction enhancement together with hemolymph ecdysteroid elevation under eyestalk ablation in the female fiddler crab,Uca triangularis(Brachyura:Decapoda)

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Chinese Journal of Oceanology and Limnology 2017年第3期35卷 645-657页

作者： SUPRIYA Nagathinkal T SUDHA Kappalli krishnakumar Velayudhannair ANILKUmAR Gopinathan Post Graduate Department of Zoology and Research Centre Sree Narayana CollegeKannurKerala 670007India Department of Zoology University of MadrasGuindy CampusChennai-600 025India School of Biotechnology Chemical and Biomedical EngineeringVIT UniversityVellore 632014India

We present the results of eyestalk extirpation experiments performed on the fiddler crab, Uca triangularis at seasons of molting and reproduction, with a view to have a better understanding of the regulatory mechanisms of these two highly energy-demanding processes. Bilateral eyestalk ablation resulted in precocious acceleration of both molting and reproduction, irrespective of the season at which each experiment was conducted. The rate of accelerated ovarian growth, however, was maximum if the eyestalk ablation was conducted during August-January, the breeding season in the wild, or in February- may （molting-reproductive season）, wherein a section of the wild population would be engaged in molting and another section in breeding. The highest degree of precocious molt acceleration, on the other hand, was obtained during June-July when the population was primarily engaged in molting, but with no reproductive activity. The precocious oocyte maturation （due to de-eyestalking） was minimal in June--July. Significantly, the eyestalk ablation also resulted in a dramatic increase in the hemolymph ecdysteroid titer, revealing that a high ecdysteroid titer would have no restraining influence on vitellogenesis. No spawning was, however, observed among de-eyestalked females, even though their final oocyte size surpassed the size of the normal mature oocytes, implying that spawning is not exclusively under the control of eyestalk hormones. A comparative study performed on the viteUine components of the experimentals and the controls revealed that the precociously incorporated yolk under eyestalk ablation was biochemically impoverished. These results indicate that throughout the annual cycle, both the somatic and the reproductive growth of U. triangularis are under the influence of inhibitory principles from the eyestalks. It is also revealing that mere deprival of the inhibitory principles does not culminate into successful vitellogenesis. Arguably, the inhibitory influence from

关键词： crab molt reproduction eyestalk principles ecdysteroids

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Verifiable Badging System for scientific data reproducibility

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Blockchain(Research and Applications) 2021年第2期2卷 68-81页

作者： Swapna krishnakumar Radha Ian Taylor Jarek Nabrzyski Iain Barclay Center for Research Computing University of Notre DameIN46556USA School of Computer Science and Informatics Cardiff UniversityCardiffWalesCF103ATUK

Reproducibility can be considered as one of the basic requirements to ensure that a given research finding is accurate and *** paper presents a new layered approach that allows scientific researchers to provide a)data to fellow researchers to validate research and b)proofs of research quality to funding agencies,without revealing sensitive details associated with the *** conclude that by integrating smart contracts,blockchain technology,and self-sovereign identity into an automated system,it is possible to assert the quality of scientific materials and validate the peer review process without the need of a central authority.

关键词： Blockchain technology Self-sovereign identity Decentralized identifiers Verifiable credentials Smart contracts

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Gut microbiome in acute pancreatitis:A review based on current literature

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World Journal of Gastroenterology 2021年第30期27卷 5019-5036页

作者： Bharati Kadamb Patel Kadamb H Patel madhav Bhatia Shridhar Ganpati Iyer krishnakumar madhavan Shabbir m moochhala Department of Surgery National University of SingaporeSingapore 119228Singapore School of Applied Sciences Temasek PolytechnicSingapore 529757Singapore Department of Pathology University of OtagoChristchurch 8140New Zealand Department of Surgery Yong Loo Lin School of MedicineNational University of SingaporeSingapore 119228Singapore National University Hospital National University of SingaporeSingapore 119228Singapore Department of Pharmacology Yong Loo Lin School of MedicineNational University of SingaporeSingapore 119228Singapore

The gut microbiome is a complex microbial community,recognized for its potential role in physiology,health,and *** available evidence supports the role of gut dysbiosis in pancreatic disorders,including acute pancreatitis(AP).In AP,the presence of gut barrier damage resulting in increased mucosal permeability may lead to translocation of intestinal bacteria,necrosis of pancreatic and peripancreatic tissue,and infection,often accompanied by multiple organ dysfunction *** gut microbial homeostasis may reduce the systemic effects of AP.A growing body of evidence suggests the possible involvement of the gut microbiome in various pancreatic diseases,including *** review discusses the possible role of the gut microbiome in *** highlights AP treatment and supplementation with prebiotics,synbiotics,and probiotics to maintain gastrointestinal microbial balance and effectively reduce hospitalization,morbidity and mortality in an early *** also addresses novel therapeutic areas in the gut microbiome,personalized treatment,and provides a roadmap of human microbial contributions to AP that have potential clinical benefit.

关键词： Acute pancreatitis Gut microbiota Biomarkers Diagnostics Dysbiosis

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Optimization of Lab-Scale Preparation of Biodiesel from Rubber Seed Oil Using modified Calcium Oxide as Catalyst

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Journal of Sustainable Bioenergy Systems 2016年第3期6卷 55-65页

作者： Uma krishnakumar V. Sivasubramanian Department of Chemical Engineering National Institute of Technology Calicut (NITC) Calicut India

Statistical analysis of product yield for biodiesel preparation by transesterification process was performed using the minitab software. A standard RSm Design tool known as CCD was applied to study the transesterification reaction variables. The obtained parameters were verified experimentally for the transesterification reaction of rubber seed oil using solid metal oxide catalyst. The factors affecting the methyl ester yield during transesterification reaction were identified as the catalyst content, molar ratio of oil to alcohol and reaction time. High methyl ester yield and fast reaction rate could be obtained even if reaction temperature was relatively low, which is quite favorable to the industrial production of biodiesel from the rubber seed oil. 98.54% of methyl ester was formed from the transesterification of RSO with methanol. R-squared is a statistical measure of how close the data are to the fitted regression line. It is also known as the coefficient of determination, or the coefficient of multiple determination for multiple regression. In this study, an R2 value of 0.98 is obtained.

关键词： Biodiesel Rubber Seed Oil Transesterification Calcium Oxide

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General Variance Covariance Structures in Two-Way Random Effects models

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Applied mathematics 2013年第4期4卷 614-623页

作者： Carlos De Porres Jaya krishnakumar Department of Economics University of Geneva Geneva Switzerland

This paper examines general variance-covariance structures for the specific effects and the overall error term in a two-way random effects (RE) model. So far panel data literature has only considered these general structures in a one-way model and followed the approach of a Cholesky-type transformation to bring the model back to a “classical” one-way RE case. In this note, we first show that in a two-way setting it is impossible to find a Cholesky-type transformation when the error components have a general variance-covariance structure (which includes autocorrelation). Then we propose solutions for this general case using the spectral decomposition of the variance components and give a general transformation leading to a block-diagonal structure which can be easily handled. The results are obtained under some general conditions on the matrices involved which are satisfied by most commonly used structures. Thus our results provide a general framework for introducing new variance-covariance structures in a panel data model. We compare our results with [1] and [2] highlighting similarities and differences.

关键词： Error Components matrix Decompositions Panel Data Spectral Decompositions

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