151 research outputs found
Crystal structure and physical properties of half-doped manganite nanocrystals with size < 100nm
In this paper we report the structural and property (magnetic and electrical
transport) measurements of nanocrystals of half-doped
(LCMO) synthesized by chemical route, having
particle size down to an average diameter of 15nm. It was observed that the
size reduction leads to change in crystal structure and the room temperature
structure is arrested so that the structure does not evolve on cooling unlike
bulk samples. The structural change mainly affects the orthorhombic distortion
of the lattice. By making comparison with observed crystal structure data under
hydrostatic pressure it is suggested that the change in the crystal structure
of the nanocrystals occurs due to an effective hydrostatic pressure created by
the surface pressure on size reduction. This not only changes the structure but
also causes the room temperature structure to freeze-in. The size reduction
also does not allow the long supercell modulation needed for the Charge
Ordering, characteristic of this half-doped manganite, to set-in. The magnetic
and transport measurements also show that the Charge Ordering (CO) does not
occur when the size is reduced below a critical size. Instead, the nanocrystals
show ferromagnetic ordering down to the lowest temperatures along with metallic
type conductivity. Our investigation establishes a structural basis for the
destabilization of CO state observed in half-doped manganite nanocrystals.Comment: 11 pages, 13 Figure
Indication of a Co-Existing Phase of Quarks and Hadrons in Nucleus - Nucleus Collisions
The variation of average transverse mass of identified hadrons with charge
multiplicity have been studied for AGS, SPS and RHIC energies. The observation
of a plateau in the average transverse mass for multiplicities corresponding to
SPS energies is attributed to the formation of a co-existence phase of quark
gluon plasma and hadrons. A subsequent rise for RHIC energies may indicate a
deconfined phase in the initial state. Several possibilities which can affect
the average transverse mass are discussed. Constraints on the initial
temperature and thermalization time have been put from the various experimental
data available at SPS energies.Comment: 4 pages and 2 figures, title changed and draft modifie
Study on the effect of toxicity under highly arsenic prone zone in Nadia district of West Bengal in India
The present study was carried out on the basis of status of arsenic in soil, drinking water and plants, blood, urine and faeces of animals at arsenic prone zone. Within the ambit with the environment, the examination of animals was taken into consideration. They were screened and categorised on the degree of As toxicity. For field works animals were randomly selected from arsenic prone zone. The external manifestation indicated a complex syndrome and characteristic signs such as increased heart rate and respiratory rate, red urine, congested mucous membrane, anorexia, absence of ruminal motility, diarrhoea with blood, polyuria and unusual weight loss. The haematobiochemical changes such as low Hb level, decreased level of TEC, TLC and increased level ALT, AST, BUN and creatinine. Increased level of arsenic in urine, blood and faeces than the value of control animals could be the confirmatory indication of arsenic toxicity
Photons from Nucleus-Nucleus Collisions at Ultra-Relativistic Energies
We compare the photon emission rates from hot hadronic matter with in-medium
mass shift and Quark Gluon Plasma (QGP). It is observed that the WA98 data can
be well reproduced by hadronic initial state with initial temperature MeV if the universal scaling of temperature dependent hadronic masses are
assumed and the evolution of temperature with time is taken from transport
model or (3+1) dimensional hydrodynamics. The data can also be reproduced by
QGP initial state with similar initial temperature and non-zero initial radial
velocity.Comment: Talk given in the International Nuclear Physics Conference, at the
University of California, Berkeley, USA, during July 30 - August 3, 200
The Application of the Conjugate Gradient Method to the Solution of Transient Electromagnetic Scattering from Thin Wires
Previous approaches to the problem of computing scattering by conducting bodies have utilized the well-known marching-on-in-time solution procedures. However, these procedures are very dependent on discretization techniques and sometimes lead to instabilities as the time progresses. Moreover, the accuracy of the solution cannot be verified easily, and usually there is no error estimation. In this paper we describe the conjugate gradient method for solving transient problems. For this method, the time and space discretizations are independent of one another. The method has the advantage of a direct method as the solution is obtained in a finite number of steps and also of an iterative method since the roundoff and truncation errors are limited only to the last stage of iteration. The conjugate gradient method converges for any initial guess; however, a good initial guess may significantly reduce the computation time. Also, explicit error formulas are given for the rate of convergence of this method. Hence any problem may be solved to a prespecified degree of accuracy. The procedure is stable with respect to roundoff and truncation errors and simple to apply. As an example, we apply the method of conjugate gradient to the problem of scattering from a thin conducting wire illuminated by a Gaussian pulse. The results compare well with the marching-on-in-time procedure
A Nonstandard Schwarz Domain Decomposition Method for Finite-Element Mesh Truncation of Infinite Arrays
A nonstandard Schwarz domain decomposition method is proposed as finite-element mesh truncation for the analysis of infinite arrays. The proposed methodology provides an (asymptotic) numerically exact radiation condition regardless of the distance to the sources of the problem and without disturbing the original sparsity of the finite-element matrices. Furthermore, it works as a multi Floquet mode (propagating and evanescent) absorbing boundary condition. Numerical results illustrating main features of the proposed methodology are shown.This work was supported in part by the
National Key Research and Development Program of China under Grant
2016YFE0121600, in part by the China Postdoctoral Science Foundation
under Grant 2017M613068, in part by the National Key Research and
Development Program of China under Grant 2017YFB0202102, and in part
by the Special Program for Applied Research on Super Computation of the
NSFC-Guangdong Joint Fund under Grant U1501501
Photons from Pb-Pb Collisions at CERN SPS
High energy photon emission rate from matter created in Pb + Pb collisions at
CERN SPS energies is evaluated. The evolution of matter from the initial state
up to freeze-out has been treated within the framework of (3+1) dimensional
hydrodynamic expansion. We observe that the photon spectra measured by the WA98
experiment are well reproduced with hard QCD photons and photons from a thermal
source with initial temperature ~ 200 MeV. The effects of the spectral changes
of hadrons with temperature on the photon emission rate and on the equation of
state are studied. Photon yield for Au + Au collisions at RHIC energies is also
estimated.Comment: To appear in Phys. Rev. C (Rapid Communications
Soil-derived Natureâs Contributions to People and their contribution to the UN Sustainable Development Goals
Acknowledgments The input of PS contributes to Soils-R-GRREAT (NE/P019455/1) and the input of PS and SK contributes to the European Union's Horizon 2020 Research and Innovation Programme through project CIRCASA (grant agreement no. 774378). PR acknowledges funding from UK Greenhouse Gas Removal Programme (NE/P01982X/2). GB De Deyn acknowledges FoodShot Global for its support. TKA acknowledges the support of âTowards Integrated Nitrogen Management System (INMS) funded by the Global Environment Facility (GEF), executed through the UKâs Natural Environment Research Council (NERC). The input of DG was supported by the New Zealand Ministry of Business, Innovation and Employment (MBIE) strategic science investment fund (SSIF). PMS acknowledges support from the Australian Research Council (Project FT140100610). PMâs work on ecosystem services is supported by a National Science Foundation grant #1853759, âUnderstanding the Use of Ecosystem Services Concepts in Environmental Policyâ. LGC is funded by National Council for Scientific and Technological Development (CNPq, Brazil â grants 421668/2018-0 and 305157/2018-3) and by Lisboa2020 FCT/EU (project 028360). BS acknowledges support from the Lancaster Environment Centre Project.Peer reviewedPostprin
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