1,870 research outputs found
Rotational Corrections to in the NJL Model and Charge Conjugation
We show that the rotational corrections to , derived using the
semiclassical quantization scheme in the NJL model, possess correct properties
under charge conjugation.Comment: 4 pages, revtex, no figures, final version published in
Phys.Rev.C52(1995)42
Shear dispersion in dense granular flows
We formulate and solve a model problem of dispersion of dense granular
materials in rapid shear flow down an incline. The effective dispersivity of
the depth-averaged concentration of the dispersing powder is shown to vary as
the P\'eclet number squared, as in classical Taylor--Aris dispersion of
molecular solutes. An extensions to generic shear profiles is presented, and
possible applications to industrial and geological granular flows are noted.Comment: 6 pages, 2 figures, Springer svjour3 format; to appear in Granular
Matte
Flow rate--pressure drop relation for deformable shallow microfluidic channels
Laminar flow in devices fabricated from soft materials causes deformation of
the passage geometry, which affects the flow rate--pressure drop relation. For
a given pressure drop, in channels with narrow rectangular cross-section, the
flow rate varies as the cube of the channel height, so deformation can produce
significant quantitative effects, including nonlinear dependence on the
pressure drop [{Gervais, T., El-Ali, J., G\"unther, A. \& Jensen, K.\ F.}\ 2006
Flow-induced deformation of shallow microfluidic channels.\ \textit{Lab Chip}
\textbf{6}, 500--507]. Gervais et. al. proposed a successful model of the
deformation-induced change in the flow rate by heuristically coupling a Hookean
elastic response with the lubrication approximation for Stokes flow. However,
their model contains a fitting parameter that must be found for each channel
shape by performing an experiment. We present a perturbation approach for the
flow rate--pressure drop relation in a shallow deformable microchannel using
the theory of isotropic quasi-static plate bending and the Stokes equations
under a lubrication approximation (specifically, the ratio of the channel's
height to its width and of the channel's height to its length are both assumed
small). Our result contains no free parameters and confirms Gervais et. al.'s
observation that the flow rate is a quartic polynomial of the pressure drop.
The derived flow rate--pressure drop relation compares favorably with
experimental measurements.Comment: 20 pages, 6 figures; v2 minor revisions, accepted for publication in
the Journal of Fluid Mechanic
Conformational effects on the Circular Dichroism of Human Carbonic Anhydrase II: a multilevel computational study
Circular Dichroism (CD) spectroscopy is a powerful method for investigating conformational changes in proteins and therefore has numerous applications in structural and molecular biology. Here a computational investigation of the CD spectrum of the Human Carbonic Anhydrase II (HCAII), with main focus on the near-UV CD spectra of the wild-type enzyme and it seven tryptophan mutant forms, is presented and compared to experimental studies. Multilevel computational methods (Molecular Dynamics, Semiempirical Quantum Mechanics, Time-Dependent Density Functional Theory) were applied in order to gain insight into the mechanisms of interaction between the aromatic chromophores within the protein environment and understand how the conformational flexibility of the protein influences these mechanisms. The analysis suggests that combining CD semi empirical calculations, crystal structures and molecular dynamics (MD) could help in achieving a better agreement between the computed and experimental protein spectra and provide some unique insight into the dynamic nature of the mechanisms of chromophore interactions
Magnetic Moments of the SU(3) Octet Baryons in the semibosonized SU(3) Nambu-Jona-Lasinio Model
We investigate the magnetic moments of the SU(3) octet baryons in the
framework of the semibosonized Nambu--Jona--Lasinio model. The
rotational corrections and strange quark mass in linear order are taken
into account. We derive general relations between magnetic moments of the SU(3)
octet baryons, based on the symmetry of our model. These relations indicate
that higher order corrections such as and are
relatively small. The magnetic moments of the octet baryons predicted by our
model are quantitatively in a good agreement with experimental results within
about 15.Comment: 17 pages, RevTex, 1 postscript figur
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