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Hydropyrolysis of high molecular weight organic matter in Murchison
Hydropyrolysis of the Murchison macromolecular material releases polyaromatic compounds including phenanthrene, carbazole, fluoranthene, pyrene, chrysene, perylene, benzoperylene and coronene units with varying degrees of alklyation
Soft modes near the buckling transition of icosahedral shells
Icosahedral shells undergo a buckling transition as the ratio of Young's
modulus to bending stiffness increases. Strong bending stiffness favors smooth,
nearly spherical shapes, while weak bending stiffness leads to a sharply
faceted icosahedral shape. Based on the phonon spectrum of a simplified
mass-and-spring model of the shell, we interpret the transition from smooth to
faceted as a soft-mode transition. In contrast to the case of a disclinated
planar network where the transition is sharply defined, the mean curvature of
the sphere smooths the transitition. We define elastic susceptibilities as the
response to forces applied at vertices, edges and faces of an icosahedron. At
the soft-mode transition the vertex susceptibility is the largest, but as the
shell becomes more faceted the edge and face susceptibilities greatly exceed
the vertex susceptibility. Limiting behaviors of the susceptibilities are
analyzed and related to the ridge-scaling behavior of elastic sheets. Our
results apply to virus capsids, liposomes with crystalline order and other
shell-like structures with icosahedral symmetry.Comment: 28 pages, 6 figure
Synaptic protein levels altered in vascular dementia
Synaptic protein levels altered in vascular dementi
Cross sections for the excitation of isovector charge-exchange resonances in 208Tl
The Glauber approximation for the treatment of heavy-ion scattering, has
already been shown to give reliable predictions for the reaction cross section
in the particular case of intermediate energy charge-exchange processes. In the
present work, we couple a Glauber-type model to microscopic Random Phase
Approximation calculations of the charge-exchange excitations of Pb.
The aim is to solve the longstanding question whether the very elusive
charge-exchange isovector monopole has been really identified in the past
experiments, or other multipoles were prevalent in the observed spectra.Comment: text + 4 figures; accepted for publication in Phys. Rev.
Semi-classical buckling of stiff polymers
A quantitative theory of the buckling of a worm like chain based on a
semi-classical approximation of the partition function is presented. The
contribution of thermal fluctuations to the force-extension relation that
allows to go beyond the classical Euler buckling is derived in the linear and
non-linear regime as well. It is shown that the thermal fluctuations in the
nonlinear buckling regime increase the end-to-end distance of the semiflexible
rod if it is confined to 2 dimensions as opposed to the 3 dimensional case. Our
approach allows a complete physical understanding of buckling in D=2 and in D=3
below and above the Euler transition.Comment: Revtex, 17 pages, 4 figure
Lagrangian formulation of classical fields within Riemann-Liouville fractional derivatives
The classical fields with fractional derivatives are investigated by using
the fractional Lagrangian formulation.The fractional Euler-Lagrange equations
were obtained and two examples were studied.Comment: 9 page
Conformal invariance: from Weyl to SO(2,d)
The present work deals with two different but subtilely related kinds of
conformal mappings: Weyl rescaling in dimensional spaces and SO(2,d)
transformations. We express how the difference between the two can be
compensated by diffeomorphic transformations. This is well known in the
framework of String Theory but in the particular case of spaces. Indeed,
the Polyakov formalism describes world-sheets in terms of two-dimensional
conformal field theory. On the other hand, B. Zumino had shown that a classical
four-dimensional Weyl-invariant field theory restricted to live in Minkowski
space leads to an SO(2,4)-invariant field theory. We extend Zumino's result to
relate Weyl and SO(2,d) symmetries in arbitrary conformally flat spaces (CFS).
This allows us to assert that a classical -invariant field does not
distinguish, at least locally, between two different -dimensional CFSs.Comment: 5 pages, no figures. There are slight modifications to match with the
published versio
Probing Correlated Ground States with Microscopic Optical Model for Nucleon Scattering off Doubly-Closed-Shell Nuclei
The RPA long range correlations are known to play a significant role in
understanding the depletion of single particle-hole states observed in (e, e')
and (e, e'p) measurements. Here the Random Phase Approximation (RPA) theory,
implemented using the D1S force is considered for the specific purpose of
building correlated ground states and related one-body density matrix elements.
These may be implemented and tested in a fully microscopic optical model for NA
scattering off doubly-closed-shell nuclei. A method is presented to correct for
the correlations overcounting inherent to the RPA formalism. One-body density
matrix elements in the uncorrelated (i.e. Hartree-Fock) and correlated (i.e.
RPA) ground states are then challenged in proton scattering studies based on
the Melbourne microscopic optical model to highlight the role played by the RPA
correlations. Effects of such correlations which deplete the nuclear matter at
small radial distance (r 2 fm) and enhance its surface region, are getting
more and more sizeable as the incident energy increases. Illustrations are
given for proton scattering observables measured up to 201 MeV for the
O, Ca, Ca and Pb target nuclei. Handling the RPA
correlations systematically improves the agreement between scattering
predictions and data for energies higher than 150 MeV.Comment: 20 pages, 7 figure
Analytical Solution for the Deformation of a Cylinder under Tidal Gravitational Forces
Quite a few future high precision space missions for testing Special and
General Relativity will use optical resonators which are used for laser
frequency stabilization. These devices are used for carrying out tests of the
isotropy of light (Michelson-Morley experiment) and of the universality of the
gravitational redshift. As the resonator frequency not only depends on the
speed of light but also on the resonator length, the quality of these
measurements is very sensitive to elastic deformations of the optical resonator
itself. As a consequence, a detailed knowledge about the deformations of the
cavity is necessary. Therefore in this article we investigate the modeling of
optical resonators in a space environment. Usually for simulation issues the
Finite Element Method (FEM) is applied in order to investigate the influence of
disturbances on the resonator measurements. However, for a careful control of
the numerical quality of FEM simulations a comparison with an analytical
solution of a simplified resonator model is beneficial. In this article we
present an analytical solution for the problem of an elastic, isotropic,
homogeneous free-flying cylinder in space under the influence of a tidal
gravitational force. The solution is gained by solving the linear equations of
elasticity for special boundary conditions. The applicability of using FEM
codes for these simulations shall be verified through the comparison of the
analytical solution with the results gained within the FEM code.Comment: 23 pages, 3 figure
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