24,378 research outputs found
How Far is UP? Encouraging social interaction through children's book app design
Historically picture books have been a social medium, an item understood by a combination of child and adult readers. Book apps are a new format for picture books. These items do not commonly require an adult co-reader; the audio narration 'reads' the text to the child. How Far is UP? is a children's book app designed to foster social engagement. Through interacting with the work users uncover text that contains different information to the audio narration. Pre-literate audience will not be able to comprehend the textual aspect of the narrative. Children will require an adult to read the text aloud and to discuss the content so that together they can formulate deeper narrative meaning. This study draws on children's literary theory with the view to uncovering ways in which interactive digital storybooks can entertain, educate and foster meaningful social, intergenerational bonding
Observation of opto-mechanical multistability in a high Q torsion balance oscillator
We observe the opto-mechanical multistability of a macroscopic torsion
balance oscillator. The torsion oscillator forms the moving mirror of a
hemi-spherical laser light cavity. When a laser beam is coupled into this
cavity, the radiation pressure force of the intra-cavity beam adds to the
torsion wire's restoring force, forming an opto-mechanical potential. In the
absence of optical damping, up to 23 stable trapping regions were observed due
to local light potential minima over a range of 4 micrometer oscillator
displacement. Each of these trapping positions exhibits optical spring
properties. Hysteresis behavior between neighboring trapping positions is also
observed. We discuss the prospect of observing opto-mechanical stochastic
resonance, aiming at enhancing the signal-to-noise ratio (SNR) in gravity
experiments.Comment: 4 pages, 5 figure
Fine Structure of the 1s3p ^3P_J Level in Atomic ^4He: Theory and Experiment
We report on a theoretical calculation and a new experimental determination
of the 1s3p ^3P_J fine structure intervals in atomic ^4He. The values from the
theoretical calculation of 8113.730(6) MHz and 658.801(6) MHz for the nu_{01}
and nu_{12} intervals, respectively, disagree significantly with previous
experimental results. However, the new laser spectroscopic measurement reported
here yields values of 8113.714(28) MHz and 658.810(18) MHz for these intervals.
These results show an excellent agreement with the theoretical values and
resolve the apparent discrepancy between theory and experiment.Comment: 9 pages, 3 figure
Low Energy States of : Elements on the Doubly-Magic Nature of Ni
Excited levels were attributed to Ga for the first time
which were fed in the -decay of its mother nucleus Zn produced in
the fission of U using the ISOL technique. We show that the structure
of this nucleus is consistent with that of the less exotic proton-deficient
N=50 isotones within the assumption of strong proton Z=28 and neutron N=50
effective shell effects.Comment: 4 pages, REVTeX 4, 5 figures (eps format
In-situ characterization of the thermal state of resonant optical interferometers via tracking of their higher-order mode resonances
Thermal lensing in resonant optical interferometers such as those used for
gravitational wave detection is a concern due to the negative impact on control
signals and instrument sensitivity. In this paper we describe a method for
monitoring the thermal state of such interferometers by probing the
higher-order spatial mode resonances of the cavities within them. We
demonstrate the use of this technique to measure changes in the Advanced LIGO
input mode cleaner cavity geometry as a function of input power, and
subsequently infer the optical absorption at the mirror surfaces at the level
of 1 ppm per mirror. We also demonstrate the generation of a useful error
signal for thermal state of the Advanced LIGO power recycling cavity by
continuously tracking the first order spatial mode resonance frequency. Such an
error signal could be used as an input to thermal compensation systems to
maintain the interferometer cavity geometries in the presence of transients in
circulating light power levels, thereby maintaining optimal sensitivity and
maximizing the duty-cycle of the detectors
Near-field radiative heat transfer between macroscopic planar surfaces
Near-field radiative heat transfer allows heat to propagate across a small
vacuum gap in quantities that are several orders of magnitude greater then the
heat transfer by far-field, blackbody radiation. Although heat transfer via
near-field effects has been discussed for many years, experimental verification
of this theory has been very limited. We have measured the heat transfer
between two macroscopic sapphire plates, finding an increase in agreement with
expectations from theory. These experiments, conducted near 300 K, have
measured the heat transfer as a function of separation over mm to m and as
a function of temperature differences between 2.5 and 30 K. The experiments
demonstrate that evanescence can be put to work to transfer heat from an object
without actually touching it
Fluctuations, Saturation, and Diffractive Excitation in High Energy Collisions
Diffractive excitation is usually described by the Good--Walker formalism for
low masses, and by the triple-Regge formalism for high masses. In the
Good--Walker formalism the cross section is determined by the fluctuations in
the interaction. In this paper we show that by taking the fluctuations in the
BFKL ladder into account, it is possible to describe both low and high mass
excitation by the Good--Walker mechanism. In high energy collisions the
fluctuations are strongly suppressed by saturation, which implies that pomeron
exchange does not factorise between DIS and collisions. The Dipole Cascade
Model reproduces the expected triple-Regge form for the bare pomeron, and the
triple-pomeron coupling is estimated.Comment: 20 pages, 12 figure
Evidence for virtual Compton scattering from the proton
In virtual Compton scattering an electron is scattered off a nucleon such that the nucleon emits a photon. We show that these events can be selected experimentally, and present the first evidence for virtual Compton scattering from the proton in data obtained at the Stanford Linear Accelerator Center. The angular and energy dependence of the data is well described by a calculation that includes the coherent sum of electron and proton radiation
\pi N and \eta p deexcitation channels of the N^* and \Delta baryonic resonances between 1470 and 1680 MeV
Two reactions, pp->ppX and pp->p\pi^+X, are used to study the 1.47<M<1.68 GeV
baryonic mass range. Three different final states are considered in the
invariant masses: N^* or \Delta^+, p\pi^0, and p\eta. The last two channels are
defined by software cuts applied to the missing mass of the first reaction.
Several narrow structures are extracted with widths \sigma(\Gamma) varying
between 3 and 9 MeV. Some structures are observed in one channel but not in
others. Such nonobservation may be due either to the spectrometer momenta
limits or to the physics (e.g. no such disintegration channel is allowed from
the narrow state considered).
We tentatively conclude that the broad Particle Data Group (PDG) baryonic
resonances N(1520)D13, N(1535)S11, Delta(1600)P33, and N(1675)D15 are
collective states built from several narrow and weakly excited resonances, each
having a (much) smaller width than the one reported by PDG.Comment: 29 pages, plus 50 (.png) figures Will be published in a slightly
reduced size in Phys. Rev.
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