1,417,124 research outputs found
Energy Dependence of the Pomeron Spin-Flip
There is no theoretical reason to think that the spin-flip component of the
Pomeron is zero. One can measure the spin-flip part using Coulomb-nuclear
interference (CNI). Perturbative QCD calculations show that the spin-flip
component is sensitive to the smallest quark separation in the proton, while
the non-flip part probes the largest separation. According to HERA results on
the proton structure function at very low x the energy dependence of the
cross-section correlates with the size of the color dipole. Analysing the data
from HERA we predict that the ratio of the spin-flip to non-flip amplitude
grows with energy as , violating Regge
factorisation of the Pomeron.Comment: A few comments and references are added. Based on invited talks at
the International Workshop on Diffraction Physics, Rio de Janeiro, February
16-20, 1998, and at DIS'98, Brussels, April 4-8, 199
Reply to Comment "Invalidity of classes of approximate Hall effect calculations."
We reply to the criticism raised by Ao in his Comment (cond-mat/9801180).
Being unable to properly treat the Hall conductivity in a mixed state of
superconductors, Ao is looking for possible mistakes in microscopic and
phenomenological calculations, as well as in the corresponding experiments. The
errors in his treatment of the problem (cond-mat/9704247) are analized. We
indicate where the approach advocated by him fails to properly account for the
interaction with impurities and other sources of relaxation.Comment: reply to Comment by Ao (cond-mat/9801180) on our paper in PRL, 79,
1377 (1997), revtex file, 1 page, no figure
Rubber friction on (apparently) smooth lubricated surfaces
We study rubber sliding friction on hard lubricated surfaces. We show that
even if the hard surface appears smooth to the naked eye, it may exhibit short
wavelength roughness, which may give the dominant contribution to rubber
friction. That is, the observed sliding friction is mainly due to the
viscoelastic deformations of the rubber by the substrate surface asperities.
The presented results are of great importance for rubber sealing and other
rubber applications involving (apparently) smooth surfaces.Comment: 7 pages, 15 figure
On the dependence of the leak-rate of seals on the skewness of the surface height probability distribution
Seals are extremely useful devices to prevent fluid leakage. We present
experimental result which show that the leak-rate of seals depend sensitively
on the skewness in the height probability distribution. The experimental data
are analyzed using the critical-junction theory. We show that using the
top-power spectrum result in good agreement between theory and experiment.Comment: 5 pages, 9 figure
MRI brain classification using support vector machine
The field of medical imaging gains its importance with increase in the need of automated and efficient diagnosis in a short period of time. Other than that, medical image retrieval system is to provide a tool for radiologists to retrieve the images similar to query image in content. Magnetic resonance imaging (MRI) is an imaging technique that has played an important role in neuroscience research for studying brain images. Classification is an important part in retrieval system in order to distinguish between normal patients and those who have the possibility of having abnormalities or tumor. In this paper, we have obtained the feature related to MRI images using discrete wavelet transformation. An advanced kernel based techniques such as Support Vector Machine (SVM) for the classification of volume of MRI data as normal and abnormal will be deployed
Fluid flow at the interface between elastic solids with randomly rough surfaces
I study fluid flow at the interface between elastic solids with randomly
rough surfaces. I use the contact mechanics model of Persson to take into
account the elastic interaction between the solid walls and the Bruggeman
effective medium theory to account for the influence of the disorder on the
fluid flow. I calculate the flow tensor which determines the pressure flow
factor and, e.g., the leak-rate of static seals. I show how the perturbation
treatment of Tripp can be extended to arbitrary order in the ratio between the
root-mean-square roughness amplitude and the average interfacial surface
separation. I introduce a matrix D(Zeta), determined by the surface roughness
power spectrum, which can be used to describe the anisotropy of the surface at
any magnification Zeta. I present results for the asymmetry factor Gamma(Zeta)
(generalized Peklenik number) for grinded steel and sandblasted PMMA surfaces.Comment: 16 pages, 14 figure
Dynamic vortex mass in clean Fermi superfluids and superconductors
We calculate the dynamic vortex mass for clean Fermi superfluids including
both s- and d-wave superconductors as a response to a vortex acceleration.
Assuming a finite quasiparticle mean free time, the vortex mass appears to be a
tensor. The diagonal component dominates in the limit of long mean free time
while the off-diagonal mass takes over in the moderately clean regime.Comment: 4 pages, no figures, typeset using RevTe
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