365 research outputs found
Gold in Devono-Carboniferous red beds of northern Britain
We are grateful to D. Craw and an anonymous reviewer for comments that helped to clarify the paper. Research was funded by NERC grants NE/L001764/1 and NE/M010953/1.Peer reviewedPublisher PD
Imaging starspot evolution on Kepler target KIC 5110407 using light curve inversion
The Kepler target KIC 5110407, a K-type star, shows strong quasi-periodic
light curve fluctuations likely arising from the formation and decay of spots
on the stellar surface rotating with a period of 3.4693 days. Using an
established light-curve inversion algorithm, we study the evolution of the
surface features based on Kepler space telescope light curves over a period of
two years (with a gap of .25 years). At virtually all epochs, we detect at
least one large spot group on the surface causing a 1-10% flux modulation in
the Kepler passband. By identifying and tracking spot groups over a range of
inferred latitudes, we measured the surface differential rotation to be much
smaller than that found for the Sun. We also searched for a correlation between
the seventeen stellar flares that occurred during our observations and the
orientation of the dominant surface spot at the time of each flare. No
statistically-significant correlation was found except perhaps for the very
brightest flares, suggesting most flares are associated with regions devoid of
spots or spots too small to be clearly discerned using our reconstruction
technique. While we may see hints of long-term changes in the spot
characteristics and flare statistics within our current dataset, a longer
baseline of observation will be needed to detect the existence of a magnetic
cycle in KIC 5110407.Comment: 32 pages, 15 figures, accepted to Ap
Niobium mineralization of sedimentary carbonates, Lewisian Complex, UK
Funding This work was supported by the NERC under Grant NE/M010953/1. Acknowledgements Skilled technical support was provided by J. Johnston and J. Bowie. We are very grateful to three reviewers whose comments helped to focus the manuscript. Conceptualization, J.P.; Formal Analysis, J.S., E.H. and J.P.; Investigation, R.M., E.H., J.S. and J.P.; Data Curation, J.S.; Writing, Review & Editing, J.P., E.H. and R.M.; Project Administration, J.P.; Funding Acquisition, J.P. Open access via T&F agreementPeer reviewedPublisher PD
American Sea Power in the Old World: The United States Navy in European and Near Eastern Waters, 1865-1917
Examining the Influence of Saliency in Mobile Interface Displays
Designers spend more resources to develop better mobile experiences today than ever before. Researchers commonly use visual search efficiency as a usability measure to determine the time or effort it takes someone to perform a task. Previous research has shown that a computational visual saliency model can predict attentional deployment in stationary desktop displays. Designers can use this salience awareness to co-locate important task information with higher salience regions. Research has shown that placing targets in higher salience regions in this way improves interface efficiency. However, researchers have not tested the model in key mobile technology design dimensions such as small displays and touch screens. In two studies, we examined the influence of saliency in a mobile application interface. In the first study, we explored a saliency model’s ability to predict fixations in small mobile interfaces at three different display sizes under free-viewing conditions. In the second study, we examined the influence that visual saliency had on search efficiency while participants completed a directed search for either an interface element associated with high or low salience. We recorded reaction time to touch the targeted element on the tablet. We experimentally blocked high and low saliency interactions and subjectively measured cognitive workload. We found that a saliency model predicted fixations. In the search task, participants found highly salient targets about 900 milliseconds faster than low salient targets. Interestingly, participants did not perceive a lighter cognitive workload associated with the increase in search efficiency
Selenium and tellurium resources in Kisgruva Proterozoic volcanogenic massive sulphide deposit (Norway)
The authors are extremely grateful to Kåre Kullerud of the Norsk Bergverksmuseum (Kongsberg) for sharing his wealth of knowledge of the Kisgruva site and assisting in accessibility. The authors also wish to thank Abbie Mclaughlin (University of Aberdeen) for her assistance with XRD analysis. The authors thank the anonymous reviewers for their careful reading and corrections of the manuscript. Funding This work was supported by the UK Natural Environment Research Council (NERC); Minerals Security of Supply (SoS) Grant NE/M010953/1, Tellurium and Selenium Cycling and Supply (TeaSe).Peer reviewedPublisher PD
FUSE Observations of a Full Orbit of Hercules X-1: Signatures of Disk, Star, and Wind
We observed an entire 1.7 day orbit of the X-ray binary Hercules X-1 with the
Far Ultraviolet Spectroscopic Explorer (FUSE). Changes in the O VI 1032,1037
line profiles through eclipse ingress and egress indicate a Keplerian accretion
disk spinning prograde with the orbit. These observations may show the first
double-peaked accretion disk line profile to be seen in the Hercules X-1
system. Doppler tomograms of the emission lines show a bright spot offset from
the Roche lobe of the companion star HZ Her, but no obvious signs of the
accretion disk. Simulations show that the bright spot is too far offset from
the Roche lobe to result from uneven X-ray heating of its surface. The absence
of disk signatures in the tomogram can be reproduced in simulations which
include absorption from a stellar wind. We attempt to diagnose the state of the
emitting gas from the C III 977, C III 1175, and N III 991 emission lines. The
latter may be enhanced through Bowen fluorescence.Comment: Accepted for publication in The Astrophysical Journa
Accelerator performance analysis of the Fermilab Muon Campus
Fermilab is dedicated to hosting world-class experiments in search of new
physics that will operate in the coming years. The Muon g-2 Experiment is one
such experiment that will determine with unprecedented precision the muon
anomalous magnetic moment, which offers an important test of the Standard
Model. We describe in this study the accelerator facility that will deliver a
muon beam to this experiment. We first present the lattice design that allows
for efficient capture, transport, and delivery of polarized muon beams. We then
numerically examine its performance by simulating pion production in the
target, muon collection by the downstream beam line optics, as well as
transport of muon polarization. We finally establish the conditions required
for the safe removal of unwanted secondary particles that minimizes
contamination of the final beam.Comment: 10 p
Kepler Observations of V447 Lyr: An Eclipsing U Gem Cataclysmic Variable
We present the results of an analysis of data covering 1.5 years of the dwarf
nova V447 Lyr. We detect eclipses of the accretion disk by the mass donating
secondary star every 3.74 hrs which is the binary orbital period. V447 Lyr is
therefore the first dwarf nova in the Kepler field to show eclipses. We also
detect five long outbursts and six short outbursts showing V447 Lyr is a U Gem
type dwarf nova. We show that the orbital phase of the mid-eclipse occurs
earlier during outbursts compared to quiescence and that the width of the
eclipse is greater during outburst. This suggests that the bright spot is more
prominent during quiescence and that the disk is larger during outburst than
quiescence. This is consistent with an expansion of the outer disk radius due
to the presence of high viscosity material associated with the outburst,
followed by a contraction in quiescence due to the accretion of low angular
momentum material. We note that the long outbursts appear to be triggered by a
short outburst, which is also observed in the super-outbursts of SU UMa dwarf
novae as observed using Kepler.Comment: Accepted by MNRA
Information engine in a nonequilibrium bath
Information engines can convert thermal fluctuations of a bath at temperature
into work at rates of order per relaxation time of the
system. We show experimentally that such engines, when in contact with a bath
that is out of equilibrium, can extract much more work. We place a heavy,
micron-scale bead in a harmonic potential that ratchets up to capture favorable
fluctuations. Adding a fluctuating electric field increases work extraction up
to ten times, limited only by the strength of applied field. Our results
connect Maxwell's demon with energy harvesting and an estimate of efficiency
shows that information engines in nonequilibrium baths can greatly outperform
conventional engines.Comment: 14 pages, 9 figure
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