1,161,471 research outputs found
New q-Euler numbers and polynomials associated with p-adic q-integrals
In this paper we study q-Euler numbers and polynomials by using p-adic
q-fermionic integrals on Z_p. The methods to study q-Euler numbers and
polynomials in this paper are new.Comment: 13 page
Alignment and orientation of an adsorbed dipole molecule
Half-cycle laser pulse is applied on an absorbed molecule to investigate its
alignment and orientation behavior. Crossover from field-free to hindered
rotation motion is observed by varying the angel of hindrance of potential
well. At small hindered angle, both alignment and orientation show
sinusoidal-like behavior because of the suppression of higher excited states.
However, mean alignment decreases monotonically as the hindered angle is
increased, while mean orientation displays a minimum point at certain hindered
angle. The reason is attributed to the symmetry of wavefunction and can be
explained well by analyzing the coefficients of eigenstates.Comment: 4 pages, 4 figures, to appear in Phys. Rev. B (2004
Superconductivity at T_c ~ 14 K in Single Crystalline FeTeSe
Single crystalline FeTeSe with a sharp superconducting
transition at 14 K is synthesized via slow furnace
cooling followed by low-temperature annealing. The effect of annealing on the
chemical and superconducting inhomogeneities is carefully characterized. We
also report resistivity, magnetization, and magneto-optical images of this
crystal. Based on the Bean model, critical current density is estimated to
exceed A/cm below 5 K under zero field. Weak fish-tail
effect is identified at lower temperatures.Comment: 4 pages, 4 figure
Thermal conductivity of quantum magnetic monopoles in the frustrated pyrochlore Yb2Ti2O7
We report low-temperature thermal conductivity of pyrochlore
YbTiO, which contains frustrated spin-ice correlations with
significant quantum fluctuations. In the disordered spin-liquid regime,
exhibits a nonmonotonic magnetic field dependence, which is well
explained by the strong spin-phonon scattering and quantum monopole
excitations. We show that the excitation energy of quantum monopoles is
strongly suppressed from that of dispersionless classical monopoles. Moreover,
in stark contrast to the diffusive classical monopoles, the quantum monopoles
have a very long mean free path. We infer that the quantum monopole is a novel
heavy particle, presumably boson, which is highly mobile in a three-dimensional
spin liquid.Comment: 8 pages, 9 figure
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TDLAS Detection of propane and butane gas over the near-infrared wavelength range from 1678nm to 1686nm
It is important in the petrochemical industry that there are high sensitivity, high accuracy, low-power consumption and intrinsically safe methods for the detection of propane, butane and their gas mixtures, to provide early warning of potential explosion hazards during both storage and transportation of oil and gas. This paper proposes a 'proof of principle' method for the detection of propane and butane using a Tunable Diode Laser Absorption Spectroscopy (TDLAS) technique over the near-infrared wavelength range from 1678nm to 1686nm. This method is relatively inexpensive to implement and is thus more practical, compared with detection methods using wavelengths further into the infra-red, near 3.3μm. The minimum detectable concentration was found to be low as 300ppm for propane or butane. Importantly, the relative measurement errors were all below 3% LEL, which meets the requirements from the petrochemical and oil-gas storage and transportation industries for a field-based system for monitoring of combustible gases
Phase Separation in A-site Ordered Perovskite Manganite LaBaMnO Probed by La and Mn NMR
La- and Mn-NMR spectra demonstrate that the ground state of
the A-site ordered perovskite manganite LaBaMnO is a spatial mixture of
the ferromagnetic (FM) and antiferromagnetic (AFI(CE)) regions, which are
assigned to the metallic and the insulating charge ordered state, respectively.
This exotic coexisting state appears below 200 K via a first-order-like
formation of the AFI(CE) state inside the FM one. Mn spin-spin relaxation rate
indicates that the FM region coexisting with the AFI(CE) one in LaBaMnO
is identical to the bulk FM phase of the disordered form
LaBaMnO in spite of the absence of A-site disorder. This
suggests mesoscopic rather than nanoscopic nature of FM region in
LaBaMnO\@.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Let
A 3D Numerical Method for Studying Vortex Formation Behind a Moving Plate
In this paper, we introduce a three-dimensional numerical method for computing the wake behind a flat plate advancing perpendicular to the flow. Our numerical method is inspired by the panel method of J. Katz and A. Plotkin [J. Katz and A. Plotkin, Low-speed Aerodynamics, 2001] and the 2D vortex blob method of Krasny [R. Krasny, Lectures in Appl. Math., 28 (1991), pp. 385--402]. The accuracy of the method will be demonstrated by comparing the 3D computation at the center section of a very high aspect ratio plate with the corresponding two-dimensional computation. Furthermore, we compare the numerical results obtained by our 3D numerical method with the corresponding experimental results obtained recently by Ringuette [M. J. Ringuette, Ph.D. Thesis, 2004] in the towing tank. Our numerical results are shown to be in excellent agreement with the experimental results up to the so-called formation time
Room temperature ferromagnetic behavior in the hollandite-type titanium oxide
A hollandite-type K(x)Ti(8)O(16) polycrystalline sample has been prepared and studied by magnetization, resistivity and x-ray photoelectron spectroscopy (XPS). Room temperature ferromagnetic behavior is observed in the magnetic hysteresis measurement. The sample shows a semiconductive temperature dependence in the resistivity measurement. Analysis of the Ti 2p(3/2) core-level XPS spectrum indicates that the titanium ions have a mixed valence of Ti(4+) and Ti(3+). In addition, the valence band spectrum reveals that the 3d electrons tend to localize on Ti(3+) ions in the hollandite-type TiO(2) lattice. Also, analysis of the valence band spectrum shows that the prepared sample is a wide-gap oxide with a band gap of 3.6 eV. These results indicate that the present hollandite-type K(x)Ti(8)O(16) sample can be classified as a TiO(2)-based wide-gap semiconductor with Curie temperature above room temperature. Room temperature ferromagnetism (RTFM) decreases in the sample prepared under a strong reducing gas atmosphere, accompanied with the decrease in the resistivity. The results imply that the localized 3d electrons are responsible for the RTFM of the K(x)Ti(8)O(16) sample
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