15,649 research outputs found
The Photon Wave Function in Non-forward Diffractive Scattering with Non-vanishing Quark Masses
The light-cone Photon wave function in explicit helicity states, valid for
massive quarks and in both momentum and configuration space, is presented by
considering the leading order photon-proton hard scattering, i.e., the
splitting quark pair scatters with the proton in the Regge limit. Further we
apply it to the diffractive scattering at nonzero momentum transfer and reach a
similar factorization as in the case of zero momentum transfer.Comment: 11 pages LaTeX, 2 figures, version to appear in Phys. Rev.
Significance Analysis for Pairwise Variable Selection in Classification
The goal of this article is to select important variables that can
distinguish one class of data from another. A marginal variable selection
method ranks the marginal effects for classification of individual variables,
and is a useful and efficient approach for variable selection. Our focus here
is to consider the bivariate effect, in addition to the marginal effect. In
particular, we are interested in those pairs of variables that can lead to
accurate classification predictions when they are viewed jointly. To accomplish
this, we propose a permutation test called Significance test of Joint Effect
(SigJEff). In the absence of joint effect in the data, SigJEff is similar or
equivalent to many marginal methods. However, when joint effects exist, our
method can significantly boost the performance of variable selection. Such
joint effects can help to provide additional, and sometimes dominating,
advantage for classification. We illustrate and validate our approach using
both simulated example and a real glioblastoma multiforme data set, which
provide promising results.Comment: 28 pages, 7 figure
Accelerating charging dynamics in sub-nanometer pores
Having smaller energy density than batteries, supercapacitors have
exceptional power density and cyclability. Their energy density can be
increased using ionic liquids and electrodes with sub-nanometer pores, but this
tends to reduce their power density and compromise the key advantage of
supercapacitors. To help address this issue through material optimization, here
we unravel the mechanisms of charging sub-nanometer pores with ionic liquids
using molecular simulations, navigated by a phenomenological model. We show
that charging of ionophilic pores is a diffusive process, often accompanied by
overfilling followed by de-filling. In sharp contrast to conventional
expectations, charging is fast because ion diffusion during charging can be an
order of magnitude faster than in bulk, and charging itself is accelerated by
the onset of collective modes. Further acceleration can be achieved using
ionophobic pores by eliminating overfilling/de-filling and thus leading to
charging behavior qualitatively different from that in conventional, ionophilic
pores
Transition behavior of k-surface from hyperbola to ellipse
The transition behavior of the k-surface of a lossy anisotropic indefinite slab is investigated. It is found that, if the material loss is taken into account, the k-surface does not show a sudden change from hyperbola to the ellipse when one principle element of the permittivity tensor changes from negative to positive. In fact, after introducing a small material loss, the shape of the k-surface can be a combination of a hyperbola and an ellipse, and a selective high directional transmission can be obtained in such a slab
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