4,995 research outputs found
Lambda(1520) photoprodcution with Regge contribution
In this talk, we report our recent progresses on the Lambda(1520)
photoproduction using the effective Lagrangian approach. In addition to the
tree-level Born diagrams, we take into account the Regge-trajectories for the
possible strange-meson exchanges in the t channel. We compute the angular and
energy dependences of the production process, including polarization
observables, such as the photon-beam asymmetry and the polarization-transfer
coefficients, resulting in good qualitative agreement with current experimental
data. We also compute the K^- angle distribution function in the
Gottfried-Jackson frame, using the polarization-transfer coefficients in the z
direction.Comment: 3 pages, 1 figure, Talk given at the international conference
BARYONS'10, 7~11 Dec 2010, Osaka, Japa
Nonequilibrium noise correlations in a point contact of helical edge states
We investigate theoretically the nonequilibrium finite-frequency current
noise in a four-terminal quantum point contact of interacting helical edge
states at a finite bias voltage. Special focus is put on the effects of the
single-particle and two-particle scattering between the two helical edge states
on the fractional charge quasiparticle excitations shown in the nonequilibrium
current noise spectra. Via the Keldysh perturbative approach, we find that the
effects of the single-particle and the two-particle scattering processes on the
current noise depend sensitively on the Luttinger liquid parameter. Moreover,
the Fano factors for the auto- and cross correlations of the currents in the
terminals are distinct from the ones for tunneling between the chiral edge
states in the quantum Hall liquid. The current noise spectra in the
single-particle-scattering-dominated and the two-particle-scattering-dominated
regime are shown. Experimental implications of our results on the transport
through the helical edges in two-dimensional topological insulators are
discussed.Comment: 10 pages, 8 figure
Pilots’ visual scan pattern and situation awareness in flight operations
Introduction: Situation awareness (SA) is considered an essential prerequisite for safe flying. If the impact of visual scanning patterns on a pilot’s situation awareness could be identified in flight operations, then eye-tracking tools could be integrated with flight simulators to improve training efficiency. Method: Participating in this research were 18 qualified, mission-ready fighter pilots. The equipment included high-fidelity and fixed-base type flight simulators and mobile head-mounted eye-tracking devices to record a subject’s eye movements and SA while performing air-to-surface tasks. Results: There were significant differences in pilots’ percentage of fixation in three operating phases: preparation (M = 46.09, SD = 14.79), aiming (M = 24.24, SD = 11.03), and release and break-away (M = 33.98, SD = 14.46). Also, there were significant differences in pilots’ pupil sizes, which were largest in the aiming phase (M = 27,621, SD = 6390.8), followed by release and break-away (M = 27,173, SD = 5830.46), then preparation (M = 25,710, SD = 6078.79), which was the smallest. Furthermore, pilots with better SA performance showed lower perceived workload (M = 30.60, SD = 17.86), and pilots with poor SA performance showed higher perceived workload (M = 60.77, SD = 12.72). Pilots’ percentage of fixation and average fixation duration among five different areas of interest showed significant differences as well. Discussion: Eye-tracking devices can aid in capturing pilots’ visual scan patterns and SA performance, unlike traditional flight simulators. Therefore, integrating eye-tracking devices into the simulator may be a useful method for promoting SA training in flight operations, and can provide in-depth understanding of the mechanism of visual scan patterns and information processing to improve training effectiveness in aviation
The loop corrections to the parity-violating electron-proton elastic scattering
We calculate the two-boson-exchange (TBE) corrections to the parity asymmetry
of the elastic electron-proton scattering in a model using the formalism of
generalized parton distributions (GPDs).Comment: 7 pages, talk given at "Particle Physics, Astrophysics and Quantum
Field Theory, 75 years since Solvay" 27th-29th Nov, 2008, Singapor
On the Feature Discovery for App Usage Prediction in Smartphones
With the increasing number of mobile Apps developed, they are now closely
integrated into daily life. In this paper, we develop a framework to predict
mobile Apps that are most likely to be used regarding the current device status
of a smartphone. Such an Apps usage prediction framework is a crucial
prerequisite for fast App launching, intelligent user experience, and power
management of smartphones. By analyzing real App usage log data, we discover
two kinds of features: The Explicit Feature (EF) from sensing readings of
built-in sensors, and the Implicit Feature (IF) from App usage relations. The
IF feature is derived by constructing the proposed App Usage Graph (abbreviated
as AUG) that models App usage transitions. In light of AUG, we are able to
discover usage relations among Apps. Since users may have different usage
behaviors on their smartphones, we further propose one personalized feature
selection algorithm. We explore minimum description length (MDL) from the
training data and select those features which need less length to describe the
training data. The personalized feature selection can successfully reduce the
log size and the prediction time. Finally, we adopt the kNN classification
model to predict Apps usage. Note that through the features selected by the
proposed personalized feature selection algorithm, we only need to keep these
features, which in turn reduces the prediction time and avoids the curse of
dimensionality when using the kNN classifier. We conduct a comprehensive
experimental study based on a real mobile App usage dataset. The results
demonstrate the effectiveness of the proposed framework and show the predictive
capability for App usage prediction.Comment: 10 pages, 17 figures, ICDM 2013 short pape
Pilots’ visual scan pattern and attention distribution during the pursuit of a dynamic target
Introduction: The current research is investigating pilots’ visual
scan patterns in order to assess attention distribution during
air-to-air manoeuvers. Method: A total of thirty qualified
mission-ready fighter pilots participated in this research. Eye
movement data were collected by a portable head-mounted eye-tracking
device, combined with a jet fighter simulator. To complete the task,
pilots have to search for, pursue, and lock-on a moving target whilst
performing air-to-air tasks. Results: There were significant
differences in pilots’ saccade duration (msec) in three operating
phases including searching (M=241, SD=332), pursuing (M=311, SD=392),
and lock-on (M=191, SD=226). Also, there were significant differences
in pilots’ pupil sizes (pixel2) of which lock-on phase was the largest
(M=27237, SD=6457), followed by pursuing (M=26232, SD=6070), then
searching (M=25858, SD=6137). Furthermore, there were significant
differences between expert and novice pilots on the percentage of
fixation on the HUD, time spent looking outside the cockpit, and the
performance of situational awareness (SA). Discussion: Experienced
pilots have better SA performance and paid more attention to the HUD
but focused less outside the cockpit when compared with novice pilots.
Furthermore, pilots with better SA performance exhibited a smaller
pupil size during the operational phase of lock-on whilst pursuing
a dynamic target. Understanding pilots’ visual scan patterns and
attention distribution are beneficial to the design of interface
displays in the cockpit and in developing human factors training
syllabi to improve safety of flight operations
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