426 research outputs found
A thin plate approximation for ocean wave interactions with an ice shelf
A variational principle is proposed to derive the governing equations for the
problem of ocean wave interactions with a floating ice shelf, where the ice
shelf is modelled by the full linear equations of elasticity and has an
Archimedean draught. The variational principle is used to form a thin-plate
approximation for the ice shelf, which includes water--ice coupling at the
shelf front and extensional waves in the shelf, in contrast to the benchmark
thin-plate approximation for ocean wave interactions with an ice shelf. The
thin-plate approximation is combined with a single-mode approximation in the
water, where the vertical motion is constrained to the eigenfunction that
supports propagating waves. The new terms in the approximation are shown to
have a major impact on predictions of ice shelf strains for wave periods in the
swell regime.Comment: 19 pages, 7 figure
11 W narrow linewidth laser source at 780nm for laser cooling and manipulation of Rubidium
We present a narrow linewidth continuous laser source with over 11 Watts of
output power at 780nm, based on single-pass frequency doubling of an amplified
1560nm fibre laser with 36% efficiency. This source offers a combination of
high power, simplicity, mode quality and stability. Without any active
stabilization, the linewidth is measured to be below 10kHz. The fibre seed is
tunable over 60GHz, which allows access to the D2 transitions in 87Rb and 85Rb,
providing a viable high-power source for laser cooling as well as for
large-momentum-transfer beamsplitters in atom interferometry. Sources of this
type will pave the way for a new generation of high flux, high duty-cycle
degenerate quantum gas experiments.Comment: 5 pages, 3 figure
Optically guided linear Mach Zehnder atom interferometer
We demonstrate a horizontal, linearly guided Mach Zehnder atom interferometer
in an optical waveguide. Intended as a proof-of-principle experiment, the
interferometer utilises a Bose-Einstein condensate in the magnetically
insensitive |F=1,mF=0> state of Rubidium-87 as an acceleration sensitive test
mass. We achieve a modest sensitivity to acceleration of da = 7x10^-4 m/s^2.
Our fringe visibility is as high as 38% in this optically guided atom
interferometer. We observe a time-of-flight in the waveguide of over half a
second, demonstrating the utility of our optical guide for future sensors.Comment: 6 pages, 3 figures. Submitted to Phys. Rev.
The consistency of superior face recognition skills in police officers
In recent years, there has been increasing interest in people with superior face
recognition skills. Yet identification of these individuals has mostly relied on criterion
performance on a single attempt at a single measure of face memory. The current
investigation aimed to examine the consistency of superior face recognition skills in
30 police officers, both across tests that tap into the same process and between tests
that tap into different components of face processing. Overall indices of performance
across related measures were found to identify different superior performers to
isolated test scores. Further, different top performers emerged for target‐present
versus target‐absent indices, suggesting that signal detection measures are the
most useful indicators of performance. Finally, a dissociation was observed between
superior memory and matching performance. Super‐recognizer screening programmes
should therefore include overall indices summarizing multiple attempts at related tests,
allowing for individuals to rank highly on different (and sometimes very specific) tasks
Model predictions of wave overwash extent into the marginal ice zone
A model of the extent of wave driven overwash into fields of sea ice floes is
proposed. The extent model builds on previous work modelling wave overwash of a
single floe by regular waves by including irregular incoming waves and random
floe fields. The model is validated against a laboratory experiment. It is then
used to study the extent of wave overwash into marginal ice zones consisting of
pancake and fragmented floe fields. The effects of wave conditions and floe
geometry on predicted extents are investigated. Finally, the model is used to
predict the wave overwash extent for the conditions observed during a winter
(July) 2017 Antarctic voyage in which the sea surface was monitored by a
stereo-camera system
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