9,486 research outputs found
Generating EPR beams in a cavity optomechanical system
We propose a scheme to produce continuous variable entanglement between
phase-quadrature amplitudes of two light modes in an optomechanical system. For
proper driving power and detuning, the entanglement is insensitive with bath
temperature and of mechanical oscillator. Under realistic experimental
conditions, we find that the entanglement could be very large even at room
temperature.Comment: 4.1 pages, 4 figures, comments are welcome; to appear in PRA,
published version with corrections of typo
Anisotropy, Itineracy, and Magnetic Frustration in High-Tc Iron Pnictides
Using first-principle density functional theory calculations combined with
insight from a tight-binding representation, dynamical mean field theory, and
linear response theory, we have extensively investigated the electronic
structures and magnetic interactions of nine ferropnictides representing three
different structural classes. The calculated magnetic interactions are found to
be short-range, and the nearest () and next-nearest () exchange
constants follow the universal trend of J_{1a}/2J_{2}\sim 1, despite their
itinerant origin and extreme sensitivity to the z-position of As. These results
bear on the discussion of itineracy versus magnetic frustration as the key
factor in stabilizing the superconducting ground state. The calculated spin
wave dispersions show strong magnetic anisotropy in the Fe plane, in contrast
to cuprates.Comment: Fig.4 updated: Phys. Rev. Lett (in press
A note on on-line broadcast scheduling with deadlines
In this paper, we study an on-line broadcast scheduling problem with deadlines, in which the requests asking for the same page can be satisfied simultaneously by broadcasting this page, and every request is associated with a release time, deadline and a required page with a unit size. The objective is to maximize the number of requests satisfied by the schedule. In this paper, we focus on an important special case where all the requests have their spans (the difference between release time and deadline) less than 2. We give an optimal online algorithm, i.e., its competitive ratio matches the lower bound of the problem.postprin
Eye-tracking experimental study investigating the influence factors of construction safety hazard recognition
Construction site accidents can be reduced if hazards leading to accidents are correctly and promptly detected by employees. Proactive safety measures such as safety perception and safety detection capability of employees play an important role in improving the safety performance. This study was initiated by three research questions related to (1) the measurement indicators of employees’ cognitive load in recognizing safety hazards; (2) site condition factors (e.g., brightness) that can affect subjects’ cognitive load; and (3) the quantification of the effects of these site factors on cognitive load. An eye-tracking experimental approach was adopted by recruiting a total of 55 students from construction management or other civil engineering disciplines to visually search hazards in 20 given site scenes. These site scenes were defined by a combination of three different categories, namely distinctiveness of hazards, site brightness, and tidiness. Quantitative measurements of experimental participants’ visual search patterns were obtained from data captured by the eye-tracking apparatus. Based on metrics related to experimental participants’ fixation, visual search track, and attention map, these measurements were computed to evaluate participants’ cognitive load in detecting hazards. Descriptive statistical comparisons analyzed these metrics under predefined categories of site conditions, i.e., distinctness versus obscurity/blurriness, brightness versus darkness, and tidiness versus messiness. The findings revealed that distinct site conditions reduced participants’ time in saccades to search hazards but did not improve the accuracy rate of first fixation; messy sites with disorganized items increased participants’ cognitive load in detecting hazards in terms of all five measurement items (i.e., accuracy rate of first fixation, fixation count, intersection coefficient, fixation duration, and fixation count in the attention center); the effect of increased brightness on-site needs further studies to determine the optimal balance of brightness level and allocation. Recommendations based on the findings were provided to enhance safety education in terms of site hazard distinctiveness, brightness, and housekeeping best practice. This study extended a few prior studies of adopting eye-tracking technology for safety monitoring by evaluating the impacts of site conditions on participants’ cognitive load, which was linked to their hazard detection performance. The study provided insights for evaluating construction employees’ hazard detection capabilities to enhance safety education. Future work is proposed to evaluate employees’ safety hazard detection pattern under dynamic construction scenarios
Airport taxi situation awareness with a macroscopic distribution network analysis
This paper proposes a framework for airport taxi situation awareness to enhance the assessment of aircraft ground movements in complex airport surfaces. Through a macroscopic distribution network (MDN) of arrival and departure taxi processes in a spatial-temporal domain, we establish two sets of taxi situation indices (TSIs) from the perspectives of single aircraft and the whole network. These TSIs are characterized into five categories: aircraft taxi time indices (ATTIs), surface instantaneous flow indices (SIFIs), surface cumulative flow indices (SCFIs), aircraft queue length indices (AQLIs), and slot resource demand indices (SRDIs). The coverage of the TSIs system is discussed in detail based on the departure and arrival reference aircraft. A real-world case study of Shanghai Pudong airport demonstrates significant correlations among some of the proposed TSIs such as the ATTIs, SCFIs and AQLIs. We identify the most crucial influencing factors of the taxi process and propose two new metrics to assess the taxi situation at the aircraft and network levels, by establishing taxi situation assessment models instead of using two systems of multiple TSIs. The findings can provide significant references to decision makers regarding airport ground movements for the purposes of air traffic scheduling and congestion control in complex airports
Exceptionally elevated triglyceride in severe lipemia retinalis
PURPOSE: To report a case of successful treatment for severe lipemia retinalis with extreme severe hypertriglyceridemia (sHTG). DESIGN: Observational case report. OBSERVATIONS: A 6-week-old infant with severe lipemia retinalis manifested diffuse creamy retinal vessels complicated with vulvar xanthomas. Extreme sHTG with 185-folds of the normal level was reported. Chromosome microarray and lipid gene sequencing confirmed a homozygous lipoprotein lipase gene coding mutation. RESULTS: Under strict adherence to a high medium-chain triglycerides formula and discontinuation of breast milk, the lipemia retinalis and vulval lesions resolved along with a stable plasma lipid level throughout the follow-up period of 6 months. CONCLUSION: Strict adherence to a low-fat diet without breast milk appears to be effective in treating infants with severe lipemia retinalis associated with exceptionally high triglycerides
Defining and Testing a Safety Cognition Framework Incorporating Safety Hazard Perception
This material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers. This material may be found at https://ascelibrary.org/doi/10.1061/%28ASCE%29CO.1943-7862.0001718
There has been insufficient research focusing on checking the reliability of construction employees’ hazard perceptions by comparing them with empirical safety data. There have also been limited studies focusing on how site employees’ perceptions could be affected by multiple external and internal factors such as workers’ experience levels
Experimental Decoy Quantum Key Distribution Up To 130KM Fiber
Decoy State Quantum Key Distribution (QKD), being capable of beating PNS
attack and uncon- ditionally secure, have become an attractive one recently.
But, in many QKD systems, disturbances of transmission channel make quantum bit
error rate (QBER) increase which limits both security distance and key bit rate
of real-life decoy state QKD systems. We demonstrate the two-intensity decoy
QKD with one-way Faraday-Michelson phase modulation system, which is free of
channel dis- turbance and keeps interference fringe visibility (99%) long
period, near 130KM single mode optical fiber in telecom (1550 nm) wavelength.
This is longest distance fiber decoy state QKD system based on two intensity
protocol.Comment: 4 pages, 2figure
Single chargino production via gluon-gluon fusion in a supersymmetric theory with an explicit R-parity violation
We studied the production of single chargino
accompanied by lepton via gluon-gluon fusion at the LHC. The
numerical analysis of their production rates is carried out in the mSUGRA
scenario with some typical parameter sets. The results show that the cross
sections of the productions via gluon-gluon
collision are in the order of femto barn quantitatively at the
CERN LHC, and can be competitive with production mechanism via quark-antiquark
annihilation process.Comment: LaTex file, 18 pages, 4 EPS file
Bell violation versus geometric measure of quantum discord and their dynamical behavior
Motivated by recent numerous works on the interplay among various measures of
quantum correlations, we aim to investigate the relationship between the
violation of Clauser-Horne-Shimony-Holt (CHSH) Bell inequality and geometric
measure of quantum discord for two-qubit systems. Exact lower and upper bounds
of Bell violation versus geometric discord are obtained for a specific and
significant class of states, Bell diagonal states, and the respective states
which suffice those bounds are also characterized. The dynamical behavior of
these two quantifiers is carefully analyzed in the presence of decoherence,
including Markovian, non-Markovian, and non-back-action quantum environments.
The results suggest that Bell violation is closely related to geometric
discord, like its relationship with other entanglement monotones.Comment: Published version. 9 pages, 16 figure
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