50,535 research outputs found
CERN Accelerator Strategy
The CERN strategy for future accelerator projects is outlined and the role of
the HE-LHC inside this strategy is described.Comment: 1 page, Contribution given to the EuCARD-AccNet-EuroLumi Workshop:
The High-Energy Large Hadron Collider, Malta, Republic of Malta, 14 - 16 Oct
201
Once Upon a Time...When a Revolution Evolved to a Civil War in Syria
This paper gives an overview of how the conflict in Syria has evolved from a revolution into a sectarian civil war. Power is maintained by the ruling Assad family through promotion of the Alawite minority within the government and military. Methods of persecution on the Sunni majority by the Assad government are discussed as well as a policy of strategic expulsion of the Sunni enclave to Idlib, a city on the outskirts of Syria (bordering Turkey)
MPD thruster technology
Inhouse magnetoplasmadynamic (MPD) thruster technology is discussed. The study focussed on steady state thrusters at powers of less than 1 MW. Performance measurement and diagnostics technologies were developed for high power thrusters. Also developed was a MPD computer code. The stated goals of the program are to establish: performance and life limitation; influence of applied fields; propellant effects; and scaling laws. The presentation is mostly through graphs and charts
Spoken word classification in children and adults
Purpose: Preschool children often have difficulties in word classification, despite good
speech perception and production. Some researchers suggest they represent words
using phonetic features rather than phonemes. We examine whether there is a
progression from feature based to phoneme based processing across age groups, and
whether responses are consistent across tasks and stimuli.
Method: In Study 1, 120 3 to 5 year old children completed three tasks assessing use of
phonetic features in classification, with an additional 58 older children completing
one of the three tasks. In Study 2, all of the children, together with an additional
adult sample, completed a nonword learning task.
Results: In all four tasks, children classified words sharing phonemes as similar. In
addition, children regarded words as similar if they shared manner of articulation,
particularly word-finally. Adults also showed this sensitivity to manner, but across
the tasks there was a pattern of increasing use of phonemic information with age.
Conclusions: Children tend to classify words as similar if they share phonemes or
share manner of articulation word finally. Use of phonemic information becomes
more common with age. These findings are in line with the theory that phonological
representations become more detailed in the preschool years
Applied-field MPD thruster geometry effects
Eight MPD thruster configurations were used to study the effects of applied field strength, propellant, and facility pressure on thruster performance. Vacuum facility background pressures higher than approx. 0.12 Pa were found to greatly influence thruster performance and electrode power deposition. Thrust efficiency and specific impulse increased monotonically with increasing applied field strength. Both cathode and anode radii fundamentally influenced the efficiency specific impulse relationship, while their lengths influence only the magnitude of the applied magnetic field required to reach a given performance level. At a given specific impulse, large electrode radii result in lower efficiencies for the operating conditions studied. For all test conditions, anode power deposition was the largest efficiency loss, and represented between 50 and 80 pct. of the input power. The fraction of the input power deposited into the anode decreased with increasing applied field and anode radii. The highest performance measured, 20 pct. efficiency at 3700 seconds specific impulse, was obtained using hydrogen propellant
MPD thruster technology
The topics are presented in viewgraph form and include the following: in house program elements; performance measurements; applied-field magnetoplasmadynamic (MPD) thruster performance scaling; MPD thruster technology; thermal efficiency scaling; anode fall voltage measurements; anode power deposition studies; MPD thruster plasma modeling; MPD thruster lifetime studies; and MPD thruster performance studies
Expanded Quantum Cryptographic Entangling Probe
The paper [Howard E. Brandt, "Quantum Cryptographic Entangling Probe," Phys.
Rev. A 71, 042312 (2005)] is generalized to include the full range of error
rates for the projectively measured quantum cryptographic entangling probe.Comment: 4 page
Matched detectors as definers of force
Although quantum states nicely express interference effects, outcomes of
experimental trials show no states directly; they indicate properties of
probability distributions for outcomes. We prove categorically that probability
distributions leave open a choice of quantum states and operators and
particles, resolvable only by a move beyond logic, which, inspired or not, can
be characterized as a guess. By recognizing guesswork as inescapable in
choosing quantum states and particles, we free up the use of particles as
theoretical inventions by which to describe experiments with devices, and
thereby replace the postulate of state reductions by a theorem. By using the
freedom to invent probe particles in modeling light detection, we develop a
quantum model of the balancing of a light-induced force, with application to
models and detecting devices by which to better distinguish one source of weak
light from another. Finally, we uncover a symmetry between entangled states and
entangled detectors, a dramatic example of how the judgment about what light
state is generated by a source depends on choosing how to model the detector of
that light.Comment: 30 pages, 4 figs, LaTeX; new Introduction; new material in Secs. 4 &
5; new Sec. 6; 1 new figure, added reference
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