Experimental demonstration of a Rydberg-atom beam splitter

Inhomogeneous electric fields generated above two-dimensional electrode structures have been used to transversely split beams of helium Rydberg atoms into pairs of spatially separated components. The atomic beams had initial longitudinal speeds of between 1700 and 2000 m/s and were prepared in Rydberg states with principle quantum number $n=52$ and electric dipole moments of up to 8700 D by resonance-enhanced two-color two-photon laser excitation from the metastable 1s2s $^3$S$_1$ level. Upon exiting the beam splitter the ensembles of Rydberg atoms were separated by up to 15.6 mm and were detected by pulsed electric field ionization. Effects of amplitude modulation of the electric fields of the beam splitter were shown to cause particle losses through transitions into unconfined Rydberg-Stark states.Comment: 6 pages, 5 figure

Locating and mitigating risks to children associated with major sporting events

Despite recent efforts to blend sport and human rights, activism for children's rights in sport has historically been marginalised. The positive 'social legacy' of sport events frequently masks more problematic issues, including child exploitation. We argue that harms to children in hosting communities of major sporting events (MSEs) should be a focus for both research and intervention since the plight of such children is currently a political blind spot. The article examines the evidence for four major sources of risk for children associated with such events: child labour, displacement resulting from forced evictions for infrastructure development and street clearance, child sexual exploitation, and human trafficking affecting children. The weakness of the resulting evidence is explained in relation to the methodological and ethical difficulties of conducting research on such hidden and marginal populations and to the fact that risks to children are often masked by adult social problems. It is argued that much more robust research designs, focused specifically on children, are essential in order to verify the many assertions made about risks to children associated with MSEs. Some mitigating interventions are briefly examined and an action plan for risk-mitigation work at future MSEs is proposed. Finally, drawing on wider debates about Centres and Peripheries in social and economic theory, we question whether major international sport organisations might choose to engage with projects like child protection for strategic rather than humanitarian reasons, using them as a kind of ethical fig leaf in order to bolster their power bases against threats from the margins. © 2014 © 2014 Taylor & Francis.The Oak Foundation under Grant code OCAY-13-052

Effect of display update interval, update type, and background on perception of aircraft separation on a cockpit display on traffic information

The concept of a cockpit display of traffic information (CDTI) includes the integration of air traffic, navigation, and other pertinent information in a single electronic display in the cockpit. Concise display symbology was developed for use in later full-mission simulator evaluations of the CDTI concept. Experimental variables used included the update interval motion of the aircraft, the update type, (that is, whether the two aircraft were updated at the same update interval or not), the background (grid pattern or no background), and encounter type (straight or curved). Only the type of encounter affected performance

Perception of aircraft separation with pilot-preferred symbology on a cockpit display of traffic information

The concept of a cockpit display of traffic information (CDTI) was developed for use in later full mission simulator evaluations of the CDTI concept. Pilots chose their preferred method of displaying air traffic information for several variables. Variables included: type of background, update rate, update type, predictor type, and history type. Each pilot designed a display he felt would be most useful in flight operations. After a series of test trials, each pilot was given the opportunity to modify the display for the experimental task. For a second day of testing, they repeated the experimental task using their display as well as displays chosen by other pilots. Results indicated a variety of individual preferences in symbology and differences in the accuracy of judgments. Pilots indicated concern for clutter of the display, relationship of the displayed symbology to physical reality, and a need to perceive the relative motion of the intruder aircraft. Analysis of data indicated that pilots were able to improve their performance with practice

The effect of viewing time, time to encounter, and practice on perception of aircraft separation on a cockpit display of traffic information

The concept of a cockpit display of traffic information (CDTI) includes the integration of air traffic, navigation, and other pertinent information in a single electronic display in the cockpit. Two studies were conducted to develop a clear and concise display format for use in later full-mission simulator evaluations of the CDTI concept. Subjects were required to monitor a CDTI for specified periods of time and to make perceptual judgments concerning the future position of a single intruder aircraft in relationship to their own aircraft. Experimental variables included: type of predictor information displayed on the two aircraft symbols; time to encounter point; length of time subjects viewed the display; amount of practice; and type of encounter (straight or turning). Results show that length of viewing time had little or no effect on performance; time to encounter influenced performance with the straight predictor but did not with the curved predictor; and that learning occurred under all conditions

Pseudo-analytical solutions for stochastic options pricing using monte carlo simulation and breeding PSO-trained neural networks

We introduce a novel methodology for pricing options which uses a particle swarm trained neural network to approximate the solution of a stochastic pricing model. The performance of the network is compared to the analytical solution for European call options and the errors shown statistically comparable to Monte Carlo pricing. The work provides a proof of concept that can be extended to more complex options for which no analytical solutions exist, the pricing method presented here delivering results several orders of magnitude faster than the Monte Carlo pricing method used by default in the financial industry

A Pulsed Synchrotron for Muon Acceleration at a Neutrino Factory

A 4600 Hz pulsed synchrotron is considered as a means of accelerating cool muons with superconducting RF cavities from 4 to 20 GeV/c for a neutrino factory. Eddy current losses are held to less than a megawatt by the low machine duty cycle plus 100 micron thick grain oriented silicon steel laminations and 250 micron diameter copper wires. Combined function magnets with 20 T/m gradients alternating within single magnets form the lattice. Muon survival is 83%.Comment: 4 pages, 1 figures, LaTeX, 5th International Workshop on Neutrino Factories and Superbeams (NuFact 03), 5-11 Jun 2003, New Yor

Seasonal variations in Greenland Ice Sheet motion : Inland extent and behaviour at higher elevations

Peer reviewedPreprin