262 research outputs found
Proton-proton bremsstrahlung below and above pion-threshold: the influence of the -isobar
The proton-proton bremsstrahlung is investigated within a coupled-channel
model with the degree of freedom. The model is consistent with the
scattering up to 1 GeV and the vertex determined in the
study of pion photoproduction reactions. It is found that the
excitation can significantly improve the agreements with the at MeV. Predictions at and MeV are
presented for future experimental tests.Comment: 26 pages Revtex, 12 figures are available from the authors upon
request ([email protected]
decay within unitarized chiral perturbation theory
We improve the calculations of the decay
within the context of meson chiral lagrangians. We use a chiral unitary
approach for the meson-meson interaction, thus generating the
resonance and fixing the longstanding sign ambiguity on its contribution. This
also allows us to calculate the loops with one vector meson exchange, thus
removing a former source of uncertainty. In addition we ensure the consistency
of the approach with other processes. First, by using vector meson dominance
couplings normalized to agree with radiative vector meson decays. And, second,
by checking the consistency of the calculations with the related reaction. We find an decay width
of eV, in clear disagreement with published data but in
remarkable agreement with the most recent measurement.Comment: 15 pages, 10 figures, published versio
Head Mounted Display Interaction Evaluation: Manipulating Virtual Objects in Augmented Reality
Augmented Reality (AR) is getting close to real use cases,which is driving the creation of innovative applications and the unprecedented growth of Head-Mounted Display (HMD) devices in consumer availability. However, at present there is a lack of guidelines, common form factors and standard interaction paradigms between devices, which has resulted in each HMD manufacturer creating their own specifications. This paper presents the first experimental evaluation of two AR HMDs evaluating their interaction paradigms, namely we used the HoloLens v1 (metaphoric interaction) and Meta2 (isomorphic interaction). We report on precision, interactivity and usability metrics in an object manipulation task-based user study. 20 participants took part in this study and significant differences were found between interaction paradigms of the devices for move tasks, where the isomorphic mapped interaction outperformed the metaphoric mapped interaction in both time to completion and accuracy, while the contrary was found for the resize task. From an interaction perspective, the isomorphic mapped interaction (using the Meta2) was perceived as more natural and usable with a significantly higher usability score and a significantly lower task-load index. However, when task accuracy and time to completion is key mixed interaction paradigms need to be considered
Down-regulation of porin M35 in Moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins
The outer membrane protein M35 of Moraxella catarrhalis is an antigenically conserved porin. Knocking out M35 significantly increases the MICs of aminopenicillins. The aim of this study was to determine the biological mechanism of this potentially new antimicrobial resistance mechanism of M. catarrhalis and the behaviour of M35 in general stress situations
New measurement of via neutron capture on hydrogen at Daya Bay
This article reports an improved independent measurement of neutrino mixing
angle at the Daya Bay Reactor Neutrino Experiment. Electron
antineutrinos were identified by inverse -decays with the emitted
neutron captured by hydrogen, yielding a data-set with principally distinct
uncertainties from that with neutrons captured by gadolinium. With the final
two of eight antineutrino detectors installed, this study used 621 days of data
including the previously reported 217-day data set with six detectors. The
dominant statistical uncertainty was reduced by 49%. Intensive studies of the
cosmogenic muon-induced Li and fast neutron backgrounds and the
neutron-capture energy selection efficiency, resulted in a reduction of the
systematic uncertainty by 26%. The deficit in the detected number of
antineutrinos at the far detectors relative to the expected number based on the
near detectors yielded in the
three-neutrino-oscillation framework. The combination of this result with the
gadolinium-capture result is also reported.Comment: 26 pages, 23 figure
Improved Measurement of the Reactor Antineutrino Flux and Spectrum at Daya Bay
A new measurement of the reactor antineutrino flux and energy spectrum by the
Daya Bay reactor neutrino experiment is reported. The antineutrinos were
generated by six 2.9~GW nuclear reactors and detected by eight
antineutrino detectors deployed in two near (560~m and 600~m flux-weighted
baselines) and one far (1640~m flux-weighted baseline) underground experimental
halls. With 621 days of data, more than 1.2 million inverse beta decay (IBD)
candidates were detected. The IBD yield in the eight detectors was measured,
and the ratio of measured to predicted flux was found to be
() for the Huber+Mueller (ILL+Vogel) model. A 2.9~
deviation was found in the measured IBD positron energy spectrum compared to
the predictions. In particular, an excess of events in the region of 4-6~MeV
was found in the measured spectrum, with a local significance of 4.4~.
A reactor antineutrino spectrum weighted by the IBD cross section is extracted
for model-independent predictions.Comment: version published in Chinese Physics
Red Imported Fire Ant in Australia: What if we lose the war?
In Australia, a national eradication programme for the Red Imported Fire Ant (Solenopsis invicta Buren), one of the world's most invasive species, has been in operation since 2001 when the pest was first detected in Brisbane, Queensland. Since that time, four separate incursions of this ant have been successfully eradicated from this country, but the main Brisbane population remains. Cost-benefit analyses already conducted put the likely impact of Red Imported Fire Ant in Australia, if not eradicated, at between A45 billion. Despite this, ongoing funding for the eradication programme is not assured. A recent external review has concluded that it remains technically feasible, cost beneficial and in the national interest to eradicate. In support of previous analyses, our study highlights some of the potential impacts of Red Imported Fire Ant in Australia in more detail and provides case examples. Results show that adverse impacts are likely in most sectors of the economy, and will be felt not only by agricultural industries, but also the building and construction, tourism, electrical and communications industries. In addition to industry effects, there will also be negative impacts on public health and lifestyle, the environment and infrastructure such as main roads, airports and schools. Our estimates of potential cost impacts in the case examples where extrapolation was possible exceed A$1.65 billion/year and support previous predictions. We conclude that increased spending is justified to avert âinvasion debtâ â the future cost of battling pests that escape today. This is a war that Australia cannot afford to lose
A new measurement of antineutrino oscillation with the full detector configuration at Daya Bay
We report a new measurement of electron antineutrino disappearance using the
fully-constructed Daya Bay Reactor Neutrino Experiment. The final two of eight
antineutrino detectors were installed in the summer of 2012. Including the 404
days of data collected from October 2012 to November 2013 resulted in a total
exposure of 6.910 GW-ton-days, a 3.6 times increase over
our previous results. Improvements in energy calibration limited variations
between detectors to 0.2%. Removal of six Am-C radioactive
calibration sources reduced the background by a factor of two for the detectors
in the experimental hall furthest from the reactors. Direct prediction of the
antineutrino signal in the far detectors based on the measurements in the near
detectors explicitly minimized the dependence of the measurement on models of
reactor antineutrino emission. The uncertainties in our estimates of
and were halved as a result of these
improvements. Analysis of the relative antineutrino rates and energy spectra
between detectors gave and eV in the three-neutrino
framework.Comment: Updated to match final published versio
Observation of electron-antineutrino disappearance at Daya Bay
The Daya Bay Reactor Neutrino Experiment has measured a non-zero value for
the neutrino mixing angle with a significance of 5.2 standard
deviations. Antineutrinos from six 2.9 GW reactors were detected in
six antineutrino detectors deployed in two near (flux-weighted baseline 470 m
and 576 m) and one far (1648 m) underground experimental halls. With a 43,000
ton-GW_{\rm th}-day livetime exposure in 55 days, 10416 (80376) electron
antineutrino candidates were detected at the far hall (near halls). The ratio
of the observed to expected number of antineutrinos at the far hall is
. A rate-only analysis
finds in a
three-neutrino framework.Comment: 5 figures. Version to appear in Phys. Rev. Let
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