4,317 research outputs found
Entire solutions of fully nonlinear elliptic equations with a superlinear gradient term
International audienceIn this paper we consider second order fully nonlinear operators with an additive superlinear gradient term. Like in the pioneering paper of Brezis for the semilinear case, we obtain the existence of entire viscosity solutions, defined in all the space, without assuming global bounds. A uniqueness result is also obtained for special gradient terms, subject to a convexity/concavity type assumption where superlinearity is essential and has to be handled in a different way from the linear case
Threshold Analysis of Non-Binary Spatially-Coupled LDPC Codes with Windowed Decoding
In this paper we study the iterative decoding threshold performance of
non-binary spatially-coupled low-density parity-check (NB-SC-LDPC) code
ensembles for both the binary erasure channel (BEC) and the binary-input
additive white Gaussian noise channel (BIAWGNC), with particular emphasis on
windowed decoding (WD). We consider both (2,4)-regular and (3,6)-regular
NB-SC-LDPC code ensembles constructed using protographs and compute their
thresholds using protograph versions of NB density evolution and NB extrinsic
information transfer analysis. For these code ensembles, we show that WD of
NB-SC-LDPC codes, which provides a significant decrease in latency and
complexity compared to decoding across the entire parity-check matrix, results
in a negligible decrease in the near-capacity performance for a sufficiently
large window size W on both the BEC and the BIAWGNC. Also, we show that
NB-SC-LDPC code ensembles exhibit gains in the WD threshold compared to the
corresponding block code ensembles decoded across the entire parity-check
matrix, and that the gains increase as the finite field size q increases.
Moreover, from the viewpoint of decoding complexity, we see that (3,6)-regular
NB-SC-LDPC codes are particularly attractive due to the fact that they achieve
near-capacity thresholds even for small q and W.Comment: 6 pages, 8 figures; submitted to 2014 IEEE International Symposium on
Information Theor
Soft-Fermion-Pole Mechanism to Single Spin Asymmetry in Hadronic Pion Production
Single spin asymmetry (SSA) is a twist-3 observable in the collinear
factorization approach. We present a twist-3 single-spin-dependent cross
section formula for the pion production in pp-collision, p^\uparrow p\to\pi X,
relevant to RHIC experiment. In particular, we calculate the soft-fermion-pole
(SFP) contribution to the cross section from the quark-gluon correlation
functions. We show that its effect can be as large as the soft-gluon-pole (SGP)
contribution owing to the large SFP partonic hard cross section, even though
the derivative of the SFP function does not participate in the cross section.Comment: 4 pages, 1 figure; to appear in the proceedings of the 18th
International Symposium on Spin Physics (SPIN2008), October 6 - 11, 2008,
Charlottesville, Virginia, US
Twist-3 Single-Spin Asymmetry for SIDIS and its Azimuthal Structure
We derive the complete twist-3 single-spin-dependent cross section for
semi-inclusive DIS, , associated with the complete set
of the twist-3 quark-gluon correlation functions in the transversely polarized
nucleon, extending our previous study. The cross section consists of five
independent structure functions with different azimuthal dependences,
consistently with the transverse-momentum-dependent (TMD) factorization
approach in the low region. Correspondence with the inclusive DIS limit
and comparison with the TMD approach are briefly discussed.Comment: 4 pages, 2 figures; to appear in the proceedings of the 18th
International Symposium on Spin Physics (SPIN2008), October 6 - 11, 2008,
Charlottesville, Virginia, US
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Evolution of mixing state of black carbon particles: Aircraft measurements over the western Pacific in March 2004
We report the evolution of the mixing state of black carbon (BC) particles in urban plumes measured by an airborne single particle soot photometer. The aircraft observations were conducted over the ocean near the coast of Japan in March 2004. The number fiaction of coated BC particles with a core diameter of 180 mn increased from 0.35 to 0.63 within 12 hours (h), namely 2.3% h-1, after being emitted from the Nagoya urban area in Japan. BC particles with a core diameter of 250 nm increased at the slower rate of 1.0% h-1. The increase in coated BC particles was associated with increases in non-sea salt sulfate and water-soluble organic carbon by a factor of approximately two, indicating that these compounds contributed to the coating on the BC particles. These results give direct evidence that BC particles become internally mixed on a time scale of 12 h in urban plumes. Copyright 2007 by the American Geophysical Union
Enhancement of electronic anomalies in iron-substituted La_2-x_Sr_x_Cu_1-y_Fe_y_O_4_ around x=0.22
We have measured the temperature dependences of Rho and Chi for
Fe-substituted La_2-x_Sr_x_Cu_1-y_Fe_y_O_4_ in the overdoped regime, in order
to investigate Fe-substitution effects on electronic properties around x=0.22.
From the Rho measurements, it has been found around x=0.22 that the values of
Rho are large at room temperature and that Rho exhibits a pronounced upturn at
low temperatures. Moreover, from the Rho and Chi measurements, it has been
found that T_c_ is anomalously depressed around x=0.22. These results indicate
that the electronic anomalies around x=0.22 are enhanced by Fe substitution,
which might be related to the development of stripe correlations by Fe
substitution.Comment: 7 pages, 3 figure
Investigation of passive flow control techniques to enhance the stall characteristics of a microlight aircraft
This report investigates the enhancement of aerodynamic stall characteristics of a Skyranger microlight aircraft by the use of passive flow control techniques, namely vortex generators and turbulators. Each flow control device is designed and scaled to application conditions. Force balance measurements and surface oil flow visualisation are carried out on a half-model of the microlight to further investigate the nature of the flow on the aircraft with and without the flow control devices. The results indicate a clear advantage to the use of turbulators compared with vortex generators. Turbulators increased the maximum lift coefficient by 2.8%, delayed the onset of stall by increasing the critical angle by 17.6% and reduced the drag penalty at both lower (pre-stall) and higher angles of attack by 8% compared to vortex generators. With vortex generators applied, the results indicated a delayed stall with an increase in the critical angle by 2% and a reduced drag penalty at higher angles of attack
Studies on the mechanism of the fluorescence decline induced by strong actinic light in PS II particles under different redox conditions
AbstractFluorescence changes induced by strong actinic light at room temperature were measured in isolated photosystem II (PS II) particles under different redox conditions. Comparative measurements of the absorption changes accompanying the light-induced fluorescence decay show that in the absence of Na2S2O4 the formation of a chlorophyll cation radical (probably together with oxidized carotenoid) causes a quenching while in the presence of Na2S2O4 photoaccumulation of the pheophytin anion radical (Pheo.−) takes place. The 695 nm band of the 77 K emission spectrum becomes specifically reduced if Pheo.− accumulates in the reaction center, whereas in the case of quenching by the cation radicals the ratio of the emission peaks at 685 nm and 695 nm remains constant. The present data favor the hypothesis that F-695 originates from the PS II reaction center [FEBS Lett. (1982) 147, 16–20]. If the primary plastoquinone acceptor (PQA) stayed oxidized in the dark before the onset of the illumination. Pheo.− photoaccumulation was not observed. This effect is explained by the existence of at least one further redox component which is able to accept electrons efficiently from Pheo.−. The proposed model also explains the differences in the redox titration curves of the electrochromic bandshift and the inital fluorescence, respectively
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