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Pictures of life in older age: a quantitative analysis of the lived experience of ageing using the Understanding Society survey
Optimisation of confinement in a fusion reactor using a nonlinear turbulence model
The confinement of heat in the core of a magnetic fusion reactor is optimised
using a multidimensional optimisation algorithm. For the first time in such a
study, the loss of heat due to turbulence is modelled at every stage using
first-principles nonlinear simulations which accurately capture the turbulent
cascade and large-scale zonal flows. The simulations utilise a novel approach,
with gyrofluid treatment of the small-scale drift waves and gyrokinetic
treatment of the large-scale zonal flows. A simple near-circular equilibrium
with standard parameters is chosen as the initial condition. The figure of
merit, fusion power per unit volume, is calculated, and then two control
parameters, the elongation and triangularity of the outer flux surface, are
varied, with the algorithm seeking to optimise the chosen figure of merit. A
two-fold increase in the plasma power per unit volume is achieved by moving to
higher elongation and strongly negative triangularity.Comment: 32 pages, 8 figures, accepted to JP
On a q-analogue of the multiple gamma functions
A -analogue of the multiple gamma functions is introduced, and is shown to
satisfy the generalized Bohr-Morellup theorem. Furthermore we give some
expressions of these function.Comment: 8 pages, AMS-Late
Spin Gap in Two-Dimensional Heisenberg Model for CaVO
We investigate the mechanism of spin gap formation in a two-dimensional model
relevant to Mott insulators such as CaVO. From the perturbation
expansion and quantum Monte Carlo calculations, the origin of the spin gap is
ascribed to the four-site plaquette singlet in contrast to the dimer gap
established in the generalized dimerized Heisenberg model.Comment: 8 pages, 6 figures available upon request (Revtex
Model for coiling and meandering instability of viscous threads
A numerical model is presented to describe both the transient and
steady-state dynamics of viscous threads falling onto a plane. The steady-state
coiling frequency w is calculated as a function of fall height H. In the case
of weak gravity, w ~ H^{-1} and w ~ H are obtained for lower and higher fall
heights respectively. When the effect of gravity is significant, the relation w
~ H^2 is observed. These results agree with the scaling laws previously
predicted. The critical Reynolds number for coil-uncoil transition is
discussed. When the gravity is weak, the transition occurs with hysteresis
effects. If the plane moves horizontally at a constant speed, a variety of
meandering oscillation modes can be observed experimentally. The present model
also can describe this phenomenon. The numerically obtained state diagram for
the meandering modes qualitatively agrees with the experiment.Comment: 12 pages, 10 figure
Activation mechanisms in sodium-doped Silicon MOSFETs
We have studied the temperature dependence of the conductivity of a silicon
MOSFET containing sodium ions in the oxide above 20 K. We find the impurity
band resulting from the presence of charges at the silicon-oxide interface is
split into a lower and an upper band. We have observed activation of electrons
from the upper band to the conduction band edge as well as from the lower to
the upper band. A possible explanation implying the presence of Hubbard bands
is given.Comment: published in J. Phys. : Condens. Matte
Early career professionals: the mission of a task force
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133554/1/jth13363_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/133554/2/jth13363.pd
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