3,862 research outputs found
Flexible control of the Peierls transition in metallic C polymers
The metal-semiconductor transition of peanut-shaped fullerene (C)
polymers is clarified by considering the electron-phonon coupling in the uneven
structure of the polymers. We established a theory that accounts for the
transition temperature reported in a recent experiment and also suggests
that is considerably lowered by electron doping or prolonged irradiation
during synthesis. The decrease in is an appealing phenomenon with regard
to realizing high-conductivity C-based nanowires even at low
temperatures.Comment: 3 pages, 3 figure
Core-tube morphology of multiwall carbon nanotubes
The present paper investigates the cross-sectional morphology of Multiwalled
Carbon Nanotubes (MWNTs) restrained radially and circumferentially by an
infinite surrounding elastic medium, subjected to uniform external hydrostatic
pressure. In this study, a two-dimensional plane strain model is developed,
assuming no variation of load and deformation along the tube axis. We find some
characteristic cross-sectional shapes from the elastic buckling analysis. The
effect of the surrounded elastic medium on the cross-sectional shape which
occurs due to pressure buckling is focused on by the comparison with the shape
for no elastic medium case in our discussion. It is suggested that in no
embedded elastic medium cases, the cross-sectional shapes of inner tubes
maintain circle or oval; on the other hand, an embedded medium may cause inner
tube corrugation modes especially when the number of shells for MWNTs is small.Comment: 7 figures, 2 figure
New Einstein-Hilbert-type Action and Superon-Graviton Model(SGM) of Nature
A nonlinear supersymmetric(NLSUSY) Einstein-Hilbert(EH)-type new action for
unity of nature is obtained by performing the Einstein gravity analogue
geomtrical arguments in high symmetry spacetime inspired by NLSUSY. The new
action is unstable and breaks down spontaneously into E-H action with matter in
ordinary Riemann spacetime. All elementary particles except graviton are
composed of the fundamental fermion "superon" of Nambu-Goldstone(NG) fermion of
NLSUSY and regarded as the eigenstates of SO(10) super-Poincar\'e (SP) algebra,
called superon-graviton model(SGM) of nature. Some phenomenological
implications for the low energy particle physics and the cosmology are
discussed. The linearization of NLSUSY including N=1 SGM action is attempted
explicitly to obtain the linear SUSY local field theory, which is equivalent
and renormalizable.Comment: 37 pages, Latex, Based on a talk by K. Shima at International
Conference on Mathematics and Nucler Physics for the 21st Century, March
8-13, 2003, Atomic Energy Authority, Cairo, Egyp
Torsion-induced persistent current in a twisted quantum ring
We describe the effects of geometric torsion on the coherent motion of
electrons along a thin twisted quantum ring. The geometric torsion inherent in
the quantum ring triggers a quantum phase shift in the electrons' eigenstates,
thereby resulting in a torsion-induced persistent current that flows along the
twisted quantum ring. The physical conditions required for detecting the
current flow are discussed.Comment: 9 pages, 3 figure
Resonant photonuclear isotope detection using medium-energy photon beam
Resonant photonuclear isotope detection (RPID) is a nondestructive
detection/assay of nuclear isotopes by measuring gamma rays following
photonuclear reaction products. Medium-energy wideband photons of 12-16 MeV are
used for the photonuclear reactions and gamma rays characteristic of the
reaction products are measured by means of high-sensitivity Ge detectors.
Impurities of stable and radioactive isotopes of the orders of micro-nano gr
and ppm-ppb are investigated. RPID is used to study nuclear isotopes of
astronuclear and particle physics interests and those of geological and
historical interests. It is used to identify radioactive isotopes of fission
products as well.Comment: 6 pages, 3 figure
Model for the unidirectional motion of a dynein molecule
Cytoplasmic dyneins transport cellular organelles by moving on a microtubule
filament. It has been found recently that depending on the applied force and
the concentration of the adenosine triphosphate (ATP) molecules, dynein's step
size varies. Based on these studies, we propose a simple model for dynein's
unidirectional motion taking into account the variations in its step size. We
study how the average velocity and the relative dispersion in the displacement
vary with the applied load. The model is amenable to further extensions by
inclusion of details associated with the structure and the processivity of the
molecule.Comment: 10 pages, 5 figure
- …