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Time-resolved evaluation of uranium plasma in different atmospheres by laser-induced breakdown spectroscopy

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Plasma Science and Technology 2018年第12期20卷 65-74页

作者： Manjeet SINGH Arnab sarkar Fuel Chemistry Division Bhabha Atomic Research CentreMumbai 400 085India Homi Bhabha National Institute AnushaktinagarMumbai 400 094India

This work reports spectroscopic studies of uranium containing plasma generated in air and argon environments. The 532 nm Q-switched Nd：YAG laser generates the optical breakdown plasma, which was recorded by a spectrometer and an intensified charge coupled device having a resolution of 25 pm. Neutral and ionized uranium lines in the wavelength range of 385.8-391.9 nm indicate significant width and shift variations during the first few microseconds. Electron temperature and density of the plasma are determined using the Boltzmann plot and the Saha-Boltzmann equation at various time delay. The study reveals the power law decay pattern of electron temperature and density, which changes to exponential decay pattern if large gate- width is used to acquire the signal, due to an averaging effect.

关键词： uranium laser induced plasma plasma parameter temporal evaluation electron temperature electron density LIBS

Targeting multiple signal pathways by chemopreventive agents for cancer prevention and therapy

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Acta Pharmacologica Sinica 2007年第9期28卷 1305-1315页

作者： Fazlul H sarkar Department of Pathology.Karmanos Cancer Institute Wayne State University School of MedicineDetroitMI 48201USA

In recent years,growing interest has been focused on the field of cancer *** prevention by chemopreventive agents offers significant promise for re-ducing the incidence and mortality of *** agents may exerttheir effects either by blocking or metabolizing carcinogens or by inhibiting tumorcell *** important benefit of chemopreventive agents is their non-toxic ***,chemopreventive agents have recently been used forcancer treatment in combination with chemotherapeutics or radiotherapy,uncov-ering a novel strategy for cancer *** strategy opens a new avenue fromcancer prevention to cancer *** vitro and in vivo studies have demon-strated that chemopreventive agents could enhance the antitumor activity ofchemotherapeutics,improving the treatment *** evidence hasshown that chemopreventive agents potentiate the efficacy of chemotherapy andradiotherapy through the regulation of multiple signaling pathways,includingAkt,NF-kB,c-Myc,cyclooxygenase-2,apoptosis,and others,suggesting amultitargeted nature of chemopreventive ***,further in-depth mecha-nistic studies,in vivo animal experiments,and clinical trials are needed to investi-gate the effects of chemopreventive agents in combination treatment of cancerwith conventional cancer *** potent natural and synthetic chemo-preventive agents are also needed to improve the efficacy of mechanism-basedand targeted therapeutic strategies against cancer,which are likely to make asignificant impact on saving ***,we have briefly reviewed the role ofchemopreventive agents in cancer prevention,but most importantly,we havereviewed how they could be useful for cancer therapy in combination with con-ventional therapies.

关键词： chemoprevention chemotherapy Akt NF-kB c-Myc cyclooxygenase-2

Effect of magnetic flux advection on the dynamics of shock in accretion flow around a rotating black hole

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Research in Astronomy and Astrophysics 2020年第3期20卷 150-161页

作者： Biplob sarkar Anjali Rao Faculty of Science&Technology The ICFAI University TripuraAgartala799210India Department of Physics and Astronomy University of Southampton.Highfield.Southampton SO 171BJUK Department of Applied Sciences Tezpur UniversityNapaam-784028.TezpurAssamIndia

We investigate the dynamical behavior of a magnetized,dissipative accretion flow around a rapidly rotating black *** solve the magnetohydrodynamic equations and calculate the transonic accretion solutions which may contain discontinuous shock *** investigate the effect ofζ-parameter(parametrizing the radial variation of the toroidal magnetic flux advection rate)on the dynamical behavior of *** a rapidly rotating black hole and for fixed injection parameters at the outer edge,we show that stationary shocks are sustained in the global magnetized accretion solutions for a wide range ofζand accretion rate(˙m).To investigate the observational implications,we consider dissipative shocks and estimate the maximum accessible energy from the post-shock corona(PSC)for nine stellar mass black hole *** compare this with the observed radio jet kinetic power reported in the literature,whenever *** find close agreement between the estimated values from our model and those reported in the literature.

关键词： accretion,accretion discs-magnetohydrodynamics-stars black holes-shock waves-ISM jets and outflows

Assessment of the fraction of bed load concentration towards the sediment transport of a monsoon-dominated river basin of Eastern India

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Journal of Geographical Sciences 2023年第5期33卷 1023-1054页

作者： KAR Rohan sarkar Arindam School of Infrastructure Indian Institute of Technology BhubaneswarArgulKhordhaOdisha 752050India

Given the challenges of re-creating complex bed load(BL)transport processes in rivers,models are preferred over gathering and examining field *** highlight of the present research is to develop an approach to determine the ungauged bed load concentration(BLC_(u))utilizing the measured suspended sediment concentration(SSC)and hydraulic variables of the last four decades for the Mahanadi River *** technique employs shear stress and SSC equations for turbulent open channel ***,the predicted BLC_(u)is correlated with SSC using a power relation to estimate BLC_(u)on the river and ***,different BL functions(BLF)efficiency is assessed across *** model predicted BLC_(u)is comparable with the published data for sandy rivers and falls within±20%.Outliers in hydraulic and sedimentological statistics significantly influence estimating the BL fraction apart from higher relative ratios and catchment *** constants of power functions are physically linked to sediment transport configuration,mechanism,and inflow to the *** stream power-based BLF best predicts the BL transport,followed by shear stress and unit discharge *** disparity in the estimation of BLC_(u)results from station-specific physical factors,sampling data dispersion,and associated uncertainties.

关键词： Mahanadi River Basin ungauged bed load concentration suspended sediment concentration correlations bed load functions

Equivariant Cobordism of Torus Orbifolds

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Chinese Annals of Mathematics,Series B 2021年第6期42卷 861-890页

作者： Soumen sarkar DongYoup SUH Department of Mathematics Indian Institute of Technology MadrasChennai 600036India Department of Mathematical Sciences KAISTDaejeon 305701Republic of Korea

Torus orbifolds are topological generalizations of symplectic toric *** authours give a construction of smooth orbifolds with torus actions whose boundary is a disjoint union of torus orbifolds using a toric topological *** a result,they show that any orientable locally standard torus orbifold is equivariantly cobordant to some copies of orbifold complex projective *** also discuss some further equivariant cobordism results including the cases when torus orbifolds are actually torus manifolds.

关键词： Manifold with corners Torus action Torus orbifolds Equivariant cobordism

On Universality of Quantum Fourier Transform

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Chinese Physics Letters 2012年第3期29卷 17-20页

作者： Arpita Maitra Santanu sarkar Applied Statistics Unit Indian Statistical Institute203 B T RoadKolkata 700108India

A methodology is presented to obtain the basis of qudits which are admissible to quantum Fourier transform(QFT)in the sense that the set of such kets are related by the QFT in the same way as the kets of the computational *** first study this method for qubits to characterize the ensemble that works for the Hadamard transformation(QFT for two dimension).In this regard we identify certain incompleteness in the result of Maitra and Parashar(*** Inform.4(2006)653).Next we characterize the ensemble of qutrits for which QFT is ***,some theoretical results related to higher dimensions are also *** the unitary matrix Un related to QFT,the issue boils down to the problem of characterizing matrices that commute with Un.

关键词： ensemble admissible dimensions

Ancient rip current records and their implications: an example from the Cretaceous Ukra Member, Kutch, India

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Journal of Palaeogeography 2020年第2期9卷 181-197页

作者： Subir sarkar Amlan Koner Department of Geological Sciences Jadavpur UniversityKolkata 700032India

Poorly-sorted conglomerate patches rich in granules or sturdy fossils or both, and reddish mud matrix within the interstices stand out amidst fine-grained siliciclastic shelf sediments of the trangressive systems tract(TST) of the Lower Cretaceous Ukra Member, Kutch Basin, India. The siliciclastic shelf sediments contrast the conglomerates with their remarkable lateral extension. The fossils belong to a low-diversity group of sedentary bivalves that can be traced into the shoreface facies assemblage. The shelf sandstones are almost always sculpted by wave structures,especially hummocky cross-stratification while textures in the conglomerates suggest that the sediment settling was generally from suspensions. Textural variations in conglomerates reflect an immediate variation in flow viscosity prior to the downloading. The current structures obtained from the conglomerates record offshoreward palaeocurrent, in contrast to the shore-parallel palaeocurrent in the TST. The hummocky cross-stratified(HCS) beds are interpreted as seasonal storm deposits, while the conglomerate patches are taken as rip current deposits induced by waves of much longer periods. The glauconite-rich shale that alternates with conglomerates is probable fair-weather products. The conglomerates could not be recognized either in the coarse-grained shoreface deposits occupying the lower part of the overall fining-upward TST or in the coarsening-upward and glauconite-depleted highstand systems tract(HST). In contrast to the TST, the HST is dominantly tide-imprinted, having shore-normal palaeocurrent direction. It appears that intensification of waves and weakening of tides during transgression favored strong rip currents generation, which had presumably caused severe damage to the sea coast and to the shell banks growing preferably at the necks of the rip current channels. Rapid lateral facies transitions in the shoreface deposits at the basal part of the TST suggest enhanced irregularity in the coast

关键词： Rip current fan Ukra Member TST shelf Longshore current Shore-normal flux Mass flow deposits Global warming Ukra Sea

Unified Smith Predictor Based H_∞ Wide-Area Damping Controller to Improve the Control Resiliency to Communication Failure

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IEEE/CAA Journal of Automatica Sinica 2020年第2期7卷 584-596页

作者： Mithu sarkar Bidyadhar Subudhi Sandip Ghosh G H Raisoni College of Engineering Nagpur 440016India Indian Institute of Technology Goa-403401India Indian Institute of Technology Banaras Hindu University(BHU)Varanasi 221005India

Inter-area low frequency oscillation in power system is one of the major problems for bulk power transmission through weak tie *** of wide-area signal is more effective than the local area signal in damping out the inter-area *** area measurement system(WAMS)is convenient to transmit the wide area signal through the communication channel to the remote *** failure is one of the disastrous phenomena in a communication *** this paper,a dual input single output(DISO)Hm controller is designed to build the control resiliency by employing two highest observability ranking wide area signals with respect to the critical damping inter-area *** proposed controller can provide sufficient damping to the system and also the system remains stabilized if one of the wide-area signals is *** time delay is an unwanted phenomenon that degrades the performance of the *** unified Smith predictor approach is used to design a Hm controller to handle the time ***'s two-area and IEEE-39 bus test systems are considered to verify the effectiveness of the proposed *** the simulation results,it is verified that,the proposed controller provides excellent damping performance at normal communication and improves the controller resiliency to counteract the communication failure.

关键词： Communication failure dual input single output(DISO)controller H_∞control inter-area oscillation unified Smith predictor

Seismic behavior of batter pile groups embedded in liquefiable soil

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Earthquake Engineering and Engineering Vibration 2021年第3期20卷 583-604页

作者： J.S.Rajeswari Rajib sarkar Department of Civil Engineering Indian Institute of Technology(ISM)DhanbadDhanbad 826004India

A comparative study of the seismic performance of 2×1 pile groups considering different degrees of batter(0°for vertical,10°and 20°)embedded in single homogeneous liquefiable sand through fully coupled three-dimensional dynamic analyses is *** effects of inertial interaction are considered with structures having two different *** performance of pile groups is investigated for the fixed and pinned pile to cap connections for both floating and end bearing types of pile *** ratios of piles were also varied to enable a comprehensive *** have been carried out for three earthquake motions having varied dominant *** is observed that batter pile groups in liquefiable soils provide beneficial effects on piles and superstructure responses for both fixed and pinned head pile to cap connections for long period ***,for short period structures,a beneficial effect is most evident for fixed head connection.

关键词： batter pile liquefaction period of structure pile to cap connection slenderness ratio