22,325 research outputs found
Negative Differential Resistance Induced by Mn Substitution at SrRuO3/Nb:SrTiO3 Schottky Interfaces
We observed a strong modulation in the current-voltage characteristics of
SrRuO/Nb:SrTiO Schottky junctions by Mn substitution in SrRuO,
which induces a metal-insulator transition in bulk. The temperature dependence
of the junction ideality factor indicates an increased spatial inhomogeneity of
the interface potential with substitution. Furthermore, negative differential
resistance was observed at low temperatures, indicating the formation of a
resonant state by Mn substitution. By spatially varying the position of the Mn
dopants across the interface with single unit cell control, we can isolate the
origin of this resonant state to the interface SrRuO layer. These results
demonstrate a conceptually different approach to controlling interface states
by utilizing the highly sensitive response of conducting perovskites to
impurities
Nanometer scale electronic reconstruction at the interface between LaVO3 and LaVO4
Electrons at interfaces, driven to minimize their free energy, are
distributed differently than in bulk. This can be dramatic at interfaces
involving heterovalent compounds. Here we profile an abrupt interface between V
3d2 LaVO3 and V 3d0 LaVO4 using electron energy loss spectroscopy. Although no
bulk phase of LaVOx with a V 3d1 configuration exists, we find a nanometer-wide
region of V 3d1 at the LaVO3/LaVO4 interface, rather than a mixture of V 3d0
and V 3d2. The two-dimensional sheet of 3d1 electrons is a prototypical
electronic reconstruction at an interface between competing ground states.Comment: 14 pages, 5 figure
Higher Fock State Contributions to the Generalized Parton Distribution of Pion
We discuss the higher Fock state (q \bar q g) contributions to the nonzero
value of the pion GPD at the crossover point x = zeta between the DGLAP and
ERBL regions. Using the phenomenological light-front constituent quark model,
we confirm that the higher Fock state contributions indeed give a nonzero value
of the GPD at the crossover point. Iterating the light-front quark model wave
function of the lowest q \bar q Fock state with the Bethe-Salpeter kernel
corresponding to the one-gluon-exchange, we include all possible time-ordered q
\bar q g Fock state contributions and obtain the pion GPD satisfying necessary
sum rules and continuity conditions.Comment: References adde
The Impact of Animated Banner Ads on Online Consumers: A Feature-Level Analysis Using Eye Tracking
Despite the popular use of animated banner ads on websites, extant research on the effects of web animation has generated mixed results. We argue that it is critical to identify feature-level animation characteristics and examine their individual and combined effects on capturing online consumers’ attention across different task conditions. We identify three key animation features (i.e., motion, lagging, and looming) based on three attention theories and investigate their effects on online consumers’ attention and recall across browsing and searching tasks in three laboratory experiments using an eye tracking machine. Experiment 1 found that both motion and looming (animation features) are effective in attracting online consumers’ attention to animated ads when they are performing a browsing task. However, combining a salient feature (e.g., motion) with another salient feature (e.g., looming) does not improve the original attention attraction effect, suggesting a “banner saturation” effect. Further, we found that online consumers’ attention positively affects their recall performance. In Experiment 2, none of the animation features or their interactions had a significant effect when the subjects were performing a searching task, indicating that task is an important boundary condition when applying attention theories. Experiment 3 replicated Experiment 1 in a more realistic context and produced similar results. We conclude the paper by discussing theoretical and practical implications as well as avenues for future research
Gravitational Waves from Axisymmetric, Rotational Stellar Core Collapse
We have carried out an extensive set of two-dimensional, axisymmetric,
purely-hydrodynamic calculations of rotational stellar core collapse with a
realistic, finite-temperature nuclear equation of state and realistic massive
star progenitor models. For each of the total number of 72 different
simulations we performed, the gravitational wave signature was extracted via
the quadrupole formula in the slow-motion, weak-field approximation. We
investigate the consequences of variation in the initial ratio of rotational
kinetic energy to gravitational potential energy and in the initial degree of
differential rotation. Furthermore, we include in our model suite progenitors
from recent evolutionary calculations that take into account the effects of
rotation and magnetic torques. For each model, we calculate gravitational
radiation wave forms, characteristic wave strain spectra, energy spectra, final
rotational profiles, and total radiated energy. In addition, we compare our
model signals with the anticipated sensitivities of the 1st- and 2nd-generation
LIGO detectors coming on line. We find that most of our models are detectable
by LIGO from anywhere in the Milky Way.Comment: 13 pages, 22 figures, accepted for publication in ApJ (v600, Jan.
2004). Revised version: Corrected typos and minor mistakes in text and
references. Minor additions to the text according to the referee's
suggestions, conclusions unchange
Comparison of data on Mutation Frequencies of Mice Caused by Radiation - Low Dose Model -
We propose LD(Low Dose) model, the extension of LDM model which was proposed
in the previous paper [Y. Manabe et al.: J. Phys. Soc. Jpn. 81 (2012) 104004]
to estimate biological damage caused by irradiation. LD model takes account of
all the considerable effects including cell death effect as well as
proliferation, apoptosis, repair. As a typical example of estimation, we apply
LD model to the experiment of mutation frequency on the responses induced by
the exposure to low levels of ionizing radiation. The most famous and extensive
experiments are those summarized by Russell and Kelly [Russell, W. L. & Kelly,
E. M: Proc. Natl Acad. Sci. USA 79 (1982) 539-541], which are known as
'Mega-mouse project'. This provides us with important information of the
frequencies of transmitted specific-locus mutations induced in mouse
spermatogonia stem-cells. It is found that the numerical results of the
mutation frequency of mice are in reasonable agreement with the experimental
data: the LD model reproduces the total dose and dose rate dependence of data
reasonably. In order to see such dose-rate dependence more explicitly, we
introduce the dose-rate effectiveness factor (DREF). This represents a sort of
preventable effects such as repair, apoptosis and death of broken cells, which
are to be competitive with proliferation effect of broken cells induced by
irradiation.Comment: subimitting to J. Phys. Soc. Jpn, 32 pages, 8 figure
Excitation of Oscillations in the Magnetic Network on the Sun
We examine the excitation of oscillations in the magnetic network of the Sun
through the footpoint motion of photospheric magnetic flux tubes located in
intergranular lanes. The motion is derived from a time series of
high-resolution G band and continuum filtergrams using an object-tracking
technique. We model the response of the flux tube to the footpoint motion in
terms of the Klein-Gordon equation, which is solved analytically as an initial
value problem for transverse (kink) waves. We compute the wave energy flux in
upward propagating transverse waves. In general we find that the injection of
energy into the chromosphere occurs in short-duration pulses, which would lead
to a time variability in chromospheric emission that is incompatible with
observations. Therefore, we consider the effects of turbulent convective flows
on flux tubes in intergranular lanes. The turbulent flows are simulated by
adding high-frequency motions (periods 5-50 s) with an amplitude of 1 km
s^{-1}. The latter are simulated by adding random velocity fluctuations to the
observationally determined velocities. In this case we find that the energy
flux is much less intermittent and can in principle carry adequate energy for
chromospheric heating.Comment: 11 pages, 5 figures, figure 1 is in color, all files gzippe
Vector-pseudoscalar two-meson distribution amplitudes in three-body meson decays
We study three-body nonleptonic decays by introducing two-meson
distribution amplitudes for the vector-pseudoscalar pair, such that the
analysis is simplified into the one for two-body decays. The twist-2 and
twist-3 two-meson distribution amplitudes, associated with
longitudinally and transversely polarized mesons, are constrained by the
experimental data of the and branching
ratios. We then predict the and decay
spectra in the invariant mass. Since the resonant contribution in the
channel is negligible, the above decay spectra provide a clean test
for the application of two-meson distribution amplitudes to three-body
meson decays.Comment: 9 pages, 1 figure, Revtex4, version to appear in PR
- …