26,040 research outputs found
Optical surface waves in periodic layered medium grown by liquid phase epitaxy
Optical surface waves propagating along the surface of a multilayer stack have been observed. The multilayer stack is grown by liquid phase epitaxy. The transverse intensity distribution measured is found to agree with our theoretical calculation
JointZone: users' view of an adaptive online learning resource for rheumatology
This paper describes an online learning resource for rheumatology that was designed for a wide constituency of users including primarily undergraduate medical students and health professionals. Although the online resources afford an informal learning environment, the site was pedagogically designed to comply with the general recommendations of the Standing Committee on Training and Education of EULAR (European League Against Rheumatism) for a rheumatology core curriculum. Any Internet user may freely browse the site content with optional registration providing access to adaptive features that personalize the user’s view, for example, providing a reading history and targeted support based on scores from completed case studies. The site has now been available since early 2003, and an online survey of site registrants indicates that well structured pedagogical materials that reflect a learners’ dominant ‘community of practice’ appear to be a successful aid to informal learning
Plasma Lens Backgrounds at a Future Linear Collider
A 'plasma lens' might be used to enhance the luminosity of future linear
colliders. However, its utility for this purpose depends largely on the
potential backgrounds that may be induced by the insertion of such a device in
the interaction region of the detector. In this note we identify different
sources of such backgrounds, calculate their event rates from the elementary
interaction processes, and evaluate their effects on the major parts of a
hypothetical Next Linear Collider (NLC) detector. For plasma lens parameters
which give a factor of seven enhancement of the luminosity, and using the NLC
design for beam parameters as a reference, we find that the background yields
are fairly high, and require further study and improvements in detector
technology to avoid their impact.Comment: 14 pages incl. 3 figures; contributed to the 4th International
Workshop, Electron-Electron Interactions at TeV Energies, Santa Cruz,
California, Dec. 7 - 9, 2001. To be published in Int.Journ. Mod. Phys.
The multiplier algebra of a nuclear quasidiagonal C*-algebra
The subject of quasidiagonality is of much interest in many places - among
other things, in the classification program for simple unital separable nuclear
C*-algebras. In this note, we give two characterizations of nuclearity and
quasidiagonality (for simple unital separable C*-algebras).
Our first characterization is the nuclear analogue of Dadarlat's
characterization of exact quasidiagonal C*-algebras. Our second
characterizatiion is "dual" to the interesting (and important) Popa property
first studied by Popa
Dynamical stability of entanglement between spin ensembles
We study the dynamical stability of the entanglement between the two spin
ensembles in the presence of an environment. For a comparative study, we
consider the two cases: a single spin ensemble, and two ensembles linearly
coupled to a bath, respectively. In both circumstances, we assume the validity
of the Markovian approximation for the bath. We examine the robustness of the
state by means of the growth of the linear entropy which gives a measure of the
purity of the system. We find out macroscopic entangled states of two spin
ensembles can stably exist in a common bath. This result may be very useful to
generate and detect macroscopic entanglement in a common noisy environment and
even a stable macroscopic memory.Comment: 4 pages, 1 figur
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