4,583 research outputs found
Recommended from our members
Local environmental action in Japan: the transfer of the groundwork approach
This paper is the basis for a report on the transfer of the UK Groundwork approach to Japan. It details the background and history of Groundwork in the UK and sets out some of the relevant context in Japan. A Japanese case study (plus two further secondary cases) is detailed and conclusions and recommendations are drawn from the work to help suggest future directions for GW and environmental action in Japan in the future
Dispersive photoluminescence decay by geminate recombination in amorphous semiconductors
The photoluminescence decay in amorphous semiconductors is described by power
law at long times. The power-law decay of photoluminescence at
long times is commonly observed but recent experiments have revealed that the
exponent, , is smaller than the value 1.5 predicted from a
geminate recombination model assuming normal diffusion. Transient currents
observed in the time-of-flight experiments are highly dispersive characterized
by the disorder parameter smaller than 1. Geminate recombination rate
should be influenced by the dispersive transport of charge carriers. In this
paper we derive the simple relation, . Not only the
exponent but also the amplitude of the decay calculated in this study is
consistent with measured photoluminescence in a-Si:H.Comment: 18pages. Submitted for the publication in Phys. Rev.
Universal Behavior in Large-scale Aggregation of Independent Noisy Observations
Aggregation of noisy observations involves a difficult tradeoff between
observation quality, which can be increased by increasing the number of
observations, and aggregation quality which decreases if the number of
observations is too large. We clarify this behavior for a protypical system in
which arbitrarily large numbers of observations exceeding the system capacity
can be aggregated using lossy data compression. We show the existence of a
scaling relation between the collective error and the system capacity, and show
that large scale lossy aggregation can outperform lossless aggregation above a
critical level of observation noise. Further, we show that universal results
for scaling and critical value of noise which are independent of system
capacity can be obtained by considering asymptotic behavior when the system
capacity increases toward infinity.Comment: 10 pages, 3 figure
Stress concentration in the vicinity of a hole defect under conditions of Hertzian contact
Two dimensional photoelastic stress analyses were conducted for epoxy resin models containing a hole defect under the conditions of Hertzian contact. Stress concentrations around the defect were determined as a function of several parameters. The effect of tangential traction on the stress concentration was also determined. Sharp stress concentrations occur in the vicinity of both the left and the right side of the hole. The stress concentration becomes more distinct the larger the hole diameter and the smaller distance between the hole and the contact surface. The stress concentration is greatest when the disk imposing a normal load is located at the contact surface directly over the hole. The magnitude and the location of stress concentration varies with the distance between the Hertzian contact area and the hole. The area involved in a process of rolling contact fatigue is confined to a shallow region at both sides of the hole. It was found that the effect of tangential traction is comparatively small on the stress concentration around the hole
Field Quantization in 5D Space-Time with Z-parity and Position/Momentum Propagator
Field quantization in 5D flat and warped space-times with Z-parity is
comparatively examined. We carefully and closely derive 5D
position/momentum(P/M) propagators. Their characteristic behaviours depend on
the 4D (real world) momentum in relation to the boundary parameter () and
the bulk curvature (\om). They also depend on whether the 4D momentum is
space-like or time-like. Their behaviours are graphically presented and the
Z symmetry, the "brane" formation and the singularities are examined. It is
shown that the use of absolute functions is important for properly treating the
singular behaviour. The extra coordinate appears as a {\it directed} one like
the temperature. The problem, which is an important consistency
check of the bulk-boundary system, is solved {\it without} the use of
KK-expansion. The relation between P/M propagator (a closed expression which
takes into account {\it all} KK-modes) and the KK-expansion-series propagator
is clarified. In this process of comparison, two views on the extra space
naturally come up: orbifold picture and interval (boundary) picture.
Sturm-Liouville expansion (a generalized Fourier expansion) is essential there.
Both 5D flat and warped quantum systems are formulated by the Dirac's bra and
ket vector formalism, which shows the warped model can be regarded as a {\it
deformation} of the flat one with the {\it deformation parameter} \om. We
examine the meaning of the position-dependent cut-off proposed by
Randall-Schwartz.Comment: 44 figures, 22(fig.)+41 pages, to be published in Phys.Rev.D, Fig.4
is improve
Quark mass uncertainties revive KSVZ axion dark matter
The Kaplan-Manohar ambiguity in light quark masses allows for a larger
uncertainty in the ratio of up to down quark masses than naive estimates from
the chiral Lagrangian would indicate. We show that it allows for a relaxation
of experimental bounds on the QCD axion, specifically KSVZ axions in the eV mass range composing 100% of the galactic dark matter halo can evade the
experimental limits placed by the ADMX collaboration.Comment: 9 pages, 5 figure
Electroweak Baryogenesis from Late Neutrino Masses
Electroweak Baryogenesis, given a first order phase transition, does not work
in the standard model because the quark Yukawa matrices are too hierarchical.
On the other hand, the neutrino mass matrix is apparently not hierarchical. In
models with neutrino mass generation at low scales, the neutrino Yukawa
couplings lead to large CP-violation in the reflection probability of heavy
leptons by the expanding Higgs bubble wall, and can generate the observed
baryon asymmetry of the universe. The mechanism predicts new vector-like
leptons below the TeV scale and sizable mu -> e processes.Comment: 5 pages, 2 figures, references adde
More Visible Effects of the Hidden Sector
There is a growing appreciation that hidden sector dynamics may affect the
supersymmetry breaking parameters in the visible sector (supersymmetric
standard model), especially when the dynamics is strong and superconformal. We
point out that there are effects that have not been previously discussed in the
literature. For example, the gaugino masses are suppressed relative to the
gravitino mass. We discuss their implications in the context of various
mediation mechanisms. The issues discussed include anomaly mediation with
singlets, the mu (B mu) problem in gauge and gaugino mediation, and distinct
mass spectra for the superparticles that have not been previously considered.Comment: 25 pages; small clarifications and corrections, version to appear in
Phys. Rev.
- …