337 research outputs found

    Functional inequalities for the Fox-Wright functions

    Get PDF
    In this paper,our aim is to establish some mean value inequalities for the Fox–Wright functions,suchasTurán-type inequalities, Lazarevic and Wilker-type inequalities. As applications we derive some new type inequalities for hypergeometric functions and thefour-parametric Mittag–Lefflerfunctions.Furthermore,weprovethemonotonicity of ratios for sections of series of Fox–Wright function

    Bahibb Issima Copts & the Public Sphere

    Get PDF
    Egypt’s Coptic community emerged dramatically onto the public sphere with the release of the film Bahibb Issima in the summer of 2004. The film’s depiction of Copts has created a national conversation between Copts and Muslims with the latter realizing not only how little they know about the Copts, but about how strikingly similar the two communities actually are. The film’s realism has been met with contestation from orthodox factions within the Coptic community while the State’s ability to control the representation of Copts in the public sphere has been challenged by the filmmakers themselves

    Analysis of Sentinel-1 radiometric stability and quality for land surface applications

    Get PDF
    International audienceLand monitoring using temporal series of Synthetic Aperture Radar (SAR) images requires radiometrically well calibrated sensors. In this paper, the radiometric stability of the new SAR Sentinel-1A 'S-1A' sensor was first assessed by analyzing temporal variations of the backscattering coefficient (sigma°) returned from invariant targets. Second, the radiometric level of invariant targets was compared from S-1A and Radarsat-2 "RS-2" data. The results show three stable sub-time series of S-1A data. The first (between 1 October 2014 and 19 March 2015) and third (between 25 November 2015 and 1 February 2016) sub-time series have almost the same mean sigma°-values (a difference lower than 0.3 dB). The mean sigma°-value of the second sub-time series (between 19 March 2015 and 25 November 2015) is higher than that of the first and the third sub-time series by roughly 0.9 dB. Moreover, our results show that the stability of each sub-time series is better than 0.48 dB. In addition, the results show that S-1A images of the first and third sub-time series appear to be well calibrated in comparison to RS-2 data, with a difference between S-1A and RS-2 lower than 0.3 dB. However, the S-1A images of the second sub-time series have sigma°-values that are higher than those from RS-2 by roughly 1 dB

    Spin dependent transport of ``nonmagnetic metal/zigzag nanotube encapsulating magnetic atoms/nonmagnetic metal'' junctions

    Full text link
    Towards a novel magnetoresistance (MR) device with a carbon nanotube, we propose ``nonmagnetic metal/zigzag nanotube encapsulating magnetic atoms/nonmagnetic metal'' junctions. We theoretically investigate how spin-polarized edges of the nanotube and the encapsulated magnetic atoms influence on transport. When the on-site Coulomb energy divided by the magnitude of transfer integral, U/tU/|t|, is larger than 0.8, large MR effect due to the direction of spins of magnetic atoms, which has the magnitude of the MR ratio of about 100%, appears reflecting such spin-polarized edges.Comment: 4 pages, 3 figures, accepted for publication in Synth. Metal

    Size-dependent alternation of magnetoresistive properties in atomic chains

    Get PDF
    Cataloged from PDF version of article.Spin-polarized electronic and transport properties of carbon atomic chains are investigated when they are capped with magnetic transition-metal (TM) atoms like Cr or Co. The magnetic ground state of the TM-C-n-TM chains alternates between the ferromagnetic (F) and antiferromagnetic (AF) spin configurations as a function of n. In view of the nanoscale spintronic device applications the desirable AF state is obtained for only even-n chains with Cr; conversely only odd-n chains with Co have AF ground states. When connected to appropriate metallic electrodes these atomic chains display a strong spin-valve effect. Analysis of structural, electronic, and magnetic properties of these atomic chains, as well as the indirect exchange coupling of the TM atoms through non-magnetic carbon atoms are presented. (c) 2006 American Institute of Physics

    Quantum heat transfer through an atomic wire

    Get PDF
    We studied the phononic heat transfer through an atomic dielectric wire with both infinite and finite lengths by using a model Hamiltonian approach. At low temperature under ballistic transport, the thermal conductance contributed by each phonon branch of a uniform and harmonic chain cannot exceed the well-known value which depends linearly on temperature but is material independent. We predict that this ballistic thermal conductance will exhibit stepwise behavior as a function of temperature. By performing numerical calculations on a more realistic system, where a small atomic chain is placed between two reservoirs, we also found resonance modes, which should also lead to the stepwise behavior in the thermal conductance.Comment: 14 pages, 2 separate figure

    Yielding and fracture mechanisms of nanowires

    Get PDF
    This paper presents a detailed analysis of atomic structure and force variations in metal nanowires under tensile strain. Our work is based on state of the art molecular dynamics simulations and ab initio self-consistent field calculations within the local density approximation, and predicts structural transformations. It is found that yielding and fracture mechanisms depend on the size, atomic arrangement, and temperature. The elongation under uniaxial stress is realized by consecutive quasielastic and yielding stages; the neck develops by the migration of atoms, but mainly by the sequential implementation of a new layer with a smaller cross section at certain ranges of uniaxial strain. This causes an abrupt decrease of the tensile force. Owing to the excessive strain at the neck, the original structure and atomic registry are modified; atoms show a tendency to rearrange in closed-packed structures. In certain circumstances, a bundle of atomic chains or a single atomic chain forms as a result of transition from the hollow site to the top site registry shortly before the break. The wire is represented by a linear combination of atomic pseudopotentials and the current is calculated to investigate the correlation between conductance variations and atomic rearrangements of the wire during the stretch. The origin of the observed "giant" yield strength is explained by using results of the present simulations and ab initio calculations of the total energy and Young's modulus for an infinite atomic chain

    Theoretical study of Ga-based nanowires and the interaction of Ga with single-wall carbon nanotubes

    Get PDF
    Gallium displays physical properties which can make it a potential element to produce metallic nanowires and high-conducting interconnects in nanoelectronics. Using first-principles pseudopotential plane method we showed that Ga can form stable metallic linear and zigzag monatomic chain structures. The interaction between individual Ga atom and single-wall carbon nanotube (SWNT) leads to a chemisorption bond involving charge transfer. Doping of SWNT with Ga atom gives rise to donor states. Owing to a significant interaction between individual Ga atom and SWNT, continuous Ga coverage of the tube can be achieved. Ga nanowires produced by the coating of carbon nanotube templates are found to be stable and high conducting.Comment: 8 pages, 8 figure

    Generalized Volterra functions, its integral representations and applications to the Mathieu-type series

    Get PDF
    In this paper we introduce the new class of generalized Volterra functions. We prove some integral representations for them via Fox-Wright H-functions and Meijer G-functions. From positivity conditions on the weight in these representations, we found sufficient conditions on parameters of the generalized Volterra function to prove its complete monotonicit

    A potential use for the C-band polarimetric SAR parameters to characterise the soil surface over bare agriculture fields

    Get PDF
    The objective of this study was to analyze the potential of the C-band polarimetric SAR parameters for the soil surface characterization of bare agricultural soils. RADARSAT-2 data and simulations using the Integral Equation Model (IEM) were analyzed to evaluate the polarimetric SAR parameters' sensitivities to the soil moisture and surface roughness. The results showed that the polarimetric parameters in the C-band were not very relevant to the characterization of the soil surface over bare agricultural areas. Low dynamics were often observed between the polarimetric parameters and both the soil moisture content and the soil surface roughness. These low dynamics do not allow for the accurate estimation of the soil parameters, but they could augment the standard inversion approaches to improve the estimation of these soil parameters. The polarimetric parameter alpha_1 could be used to detect very moist soils (>30%), while the anisotropy could be used to separate the smooth soils
    corecore