680 research outputs found
On Nontotients
AbstractLet φ(x) be Euler′s totient function. If the equation φ(x) = n has no solution, then n is called a nontotient. In this paper, we prove that a nontotient can have an arbitrary divisor and we give two sorts of odd numbers such that for the odd number k of the first sort, 2α · k is a nontotient for a given positive integer α while for the odd number k of the second sort, 2α · k is a nontotient for arbitrary positive integer α
Momentum-Resolved Inelastic X-ray Scattering as a Novel Tool to Study Charge Gap in Complex Insulators
We report particle-hole pair excitations in a cuprate insulator in the
intermediate regimes of momentum-transfers using high energy inelastic x-ray
scattering. The excitation spectra show dispersive features near the Mott edge
which shed light on the momentum structure of the upper Hubbard band in
cuprates. We briefly discuss the potential use of such a technique to study the
momentum dependence of unoccupied bands and q-dependent charge fluctuations in
complex insulators.Comment: 3 pages, 2 figures, Revise
Self-organising comprehensive handover strategy for multi-tier LTE-advanced heterogeneous networks
Long term evolution (LTE)-advanced was introduced as real fourth generation (4G) with its new features and additional functions, satisfying the growing demands of quality and network coverage for the network operators' subscribers. The term muti-tier has also been recently used with respect to the heterogeneity of the network by applying the various subnetwork cooperative systems and functionalities with self-organising capabilities. Using indoor short-range low-power cellular base stations, for example, femtocells, in cooperation with existing long-range macrocells are considered as the key technical challenge of this multi-tier configuration. Furthermore, shortage of network spectrum is a major concern for network operators which forces them to spend additional attentions to overcome the degradation in performance and quality of services in 4G HetNets. This study investigates handover between the different layers of a heterogeneous LTE-advanced system, as a critical attribute to plan the best way of interactive coordination within the network for the proposed HetNet. The proposed comprehensive handover algorithm takes multiple factors in both handover sensing and decision stages, based on signal power reception, resource availability and handover optimisation, as well as prioritisation among macro and femto stations, to obtain maximum signal quality while avoiding unnecessary handovers
Chemical Potential Shift in NdCeCuO: Contrasting Behaviors of the Electron- and Hole-Doped Cuprates
We have studied the chemical potential shift in the electron-doped
superconductor NdCeCuO by precise measurements of
core-level photoemission spectra. The result shows that the chemical potential
monotonously increases with electron doping, quite differently from
LaSrCuO, where the shift is suppressed in the underdoped
region.
If the suppression of the shift in LaSrCuO is attributed
to strong stripe fluctuations, the monotonous increase of the chemical
potential is consistent with the absence of stripe fluctuations in
NdCeCuO. The chemical potential jump between
NdCuO and LaCuO is found to be much smaller than the
optical band gaps.Comment: 4 pages, 5 figure
Crossing w=-1 in Gauss-Bonnet Brane World with Induced Gravity
Recent type Ia supernovas data seemingly favor a dark energy model whose
equation of state crosses -1 very recently, which is a much more amazing
problem than the acceleration of the universe. In this paper we show that it is
possible to realize such a crossing without introducing any phantom component
in a Gauss-Bonnet brane world with induced gravity, where a four dimensional
curvature scalar on the brane and a five dimensional Gauss-Bonnet term in the
bulk are present. In this realization, the Gauss-Bonnet term and the mass
parameter in the bulk play a crucial role.Comment: Revtex 16 pages including 10 eps files, references added, to appear
in Comm. Theor. Phy
Analysis and modeling of the root system architecture of winter wheat seedling
Plant root system plays an essential role in the acquisition of the edaphic resources, which are subject to local depletion. The size as well as the architecture of the root system determines the efficiency of the acquisition. In the present study, a stochastic model of plant root system architecture is formulated. The continuous growth and development of root system is described and modelled by stochastic processes (discrete events associated with a certain probability). The parameters of the model for each growth cycle include branching probability, w (rhythm ratio main axis vs. lateral roots), b (probability of growth) and c (probability of survival). Root segments were presented as connections of individual nodes. As root has no nodes in the sense of the botanical terms, an imaginary node with an elementary length is introduced. In order to obtain the parameters of the model, winter wheat seedlings were grown in a phytotron in sand culture watered by nutrient solution. Individual roots of 19-days-old se dlings were scanned and the images obtained were analysed with a root image-analysing software WinRhizo. Roots were clustered into 3 relatively homogeneous groups after an analysis of similarity according to 4 criteria: length of main axe, diameter of root apex of the main axe, lateral length density (total length of lateral roots per unit of main axe length), lateral root density (number of lateral roots per unit of main axe). In each root group, the parameters were fitted with a non-linear generalised least square method by comparing the theoretical length of root segments of various orders with the experimental data
Inverted type-I CdS/CdSe core/crown colloidal quantum ring
[No abstract available
Mass measurements of neutron-deficient Y, Zr, and Nb isotopes and their impact on rp and νp nucleosynthesis processes
© 2018 The Authors. Published by Elsevier B.V. This manuscript is made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licence (CC BY-NC-ND 4.0). For further details please see: https://creativecommons.org/licenses/by-nc-nd/4.0/Using isochronous mass spectrometry at the experimental storage ring CSRe in Lanzhou, the masses of 82Zr and 84Nb were measured for the first time with an uncertainty of ∼10 keV, and the masses of 79Y, 81Zr, and 83Nb were re-determined with a higher precision. The latter are significantly less bound than their literature values. Our new and accurate masses remove the irregularities of the mass surface in this region of the nuclear chart. Our results do not support the predicted island of pronounced low α separation energies for neutron-deficient Mo and Tc isotopes, making the formation of Zr–Nb cycle in the rp-process unlikely. The new proton separation energy of 83Nb was determined to be 490(400) keV smaller than that in the Atomic Mass Evaluation 2012. This partly removes the overproduction of the p-nucleus 84Sr relative to the neutron-deficient molybdenum isotopes in the previous νp-process simulations.Peer reviewe
Interface and electronic characterization of thin epitaxial Co3O4 films
The interface and electronic structure of thin (~20-74 nm) Co3O4(110)
epitaxial films grown by oxygen-assisted molecular beam epitaxy on MgAl2O4(110)
single crystal substrates have been investigated by means of real and
reciprocal space techniques. As-grown film surfaces are found to be relatively
disordered and exhibit an oblique low energy electron diffraction (LEED)
pattern associated with the O-rich CoO2 bulk termination of the (110) surface.
Interface and bulk film structure are found to improve significantly with
post-growth annealing at 820 K in air and display sharp rectangular LEED
patterns, suggesting a surface stoichiometry of the alternative Co2O2 bulk
termination of the (110) surface. Non-contact atomic force microscopy
demonstrates the presence of wide terraces separated by atomic steps in the
annealed films that are not present in the as-grown structures; the step height
of ~ 2.7 A corresponds to two atomic layers and confirms a single termination
for the annealed films, consistent with the LEED results. A model of the (1 *
1) surfaces that allows for compensation of the polar surfaces is presented.Comment: 8 pages, 7 figure
Charmless Decays in QCD Factorization
The two body charmless decays of meson to light vector mesons are
analyzed within the framework of QCD factorization. This approach implies that
the nonfactorizable corrections to different helicity amplitudes are not the
same. The effective parameters for helicity states receive
different nonfactorizable contributions and hence are helicity dependent,
contrary to naive factorization approach where are universal and
polarization independent. The branching ratios for decays are
calculated and we find that branching ratios of some channels are of order
, which are measurable at future experiments. The transverse to total
decay rate is also evaluated and found to be very small for
most decay modes, so, in charmless decays, both light vector
mesons tend to have zero helicity.Comment: 16pages. Typos and mistakes fixed. Numerical results change
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