1,772 research outputs found
The BLG Theory in Light-Cone Superspace
The light-cone superspace version of the d=3, N=8 superconformal theory of
Bagger, Lambert and Gustavsson (BLG) is obtained as a solution to constraints
imposed by OSp(2,2|8) superalgebra. The Hamiltonian of the theory is shown to
be a quadratic form of the dynamical supersymmetry transformation.Comment: 45 pages, v2: reference added, minor typos corrected, published
versio
Long range scattering resonances in strong-field seeking states of polar molecules
We present first steps toward understanding the ultracold scattering
properties of polar molecules in strong electric field-seeking states. We have
found that the elastic cross section displays a quasi-regular set of potential
resonances as a function of the electric field, which potentially offers
intimate details about the inter-molecular interaction. We illustrate these
resonances in a ``toy'' model composed of pure dipoles, and in more physically
realistic systems. To analyze these resonances, we use a simple WKB
approximation to the eigenphase, which proves both reasonably accurate and
meaningful. A general treatment of the Stark effect and dipolar interactions is
also presented
Using concept mapping to design an indicator framework for addiction treatment centers.
Objective. The objective of this study is to determine an indicator framework for addiction treatment centres based on the demands of stakeholders and in alignment with the European Foundation for Quality Management (EFQM) Excellence Model. Setting. The setting is the Jellinek Centre based in Amsterdam, the Netherlands, which serves as a prototype for an addiction treatment centre. Method. Concept mapping was used in the construction of the indicator framework. During the 1-day workshop, 16 stake-holders generated, prioritized and sorted 73 items concerning quality and performance. Multidimensional scaling and cluster analysis was applied in constructing a framework consisting of two dimensions and eight clusters. Results. The horizontal axis of the indicator framework is named 'Organization' and has two poles, namely, 'Processes' and 'Results'. The vertical axis is named 'Task' and the poles are named 'Efficient treatment' and 'Prevention programs'. The eight clusters in the two-dimensional framework are arranged in the following, prioritized sequence: 'Efficient treatment network', 'Effective service', 'Target group', 'Quality of life', 'Efficient service', 'Knowledge transfer', 'Reducing addiction related problems', and 'Prevention programs'. The most important items in the framework are: 'patients are satisfied with their treatment', 'early interventions', and 'efficient treatment chain'. Conclusion. The indicator framework aligns with three clusters of the results criteria of the EFQM Excellence Model. It is based on the stakeholders' perspectives and is believed to be specific for addiction treatment centres. The study demonstrates that concept mapping is a suitable strategy for generating indicator frameworks. © The Author 2005. Published by Oxford University Press on behalf of International Society for Quality in Health Care; all rights reserved
The quantum origins of skyrmions and half-skyrmions in Cu2OSeO3
The Skyrme-particle, the , was introduced over half a century ago
and used to construct field theories for dense nuclear matter. But with
skyrmions being mathematical objects - special types of topological solitons -
they can emerge in much broader contexts. Recently skyrmions were observed in
helimagnets, forming nanoscale spin-textures that hold promise as information
carriers. Extending over length-scales much larger than the inter-atomic
spacing, these skyrmions behave as large, classical objects, yet deep inside
they are of quantum origin. Penetrating into their microscopic roots requires a
multi-scale approach, spanning the full quantum to classical domain. By
exploiting a natural separation of exchange energy scales, we achieve this for
the first time in the skyrmionic Mott insulator CuOSeO. Atomistic ab
initio calculations reveal that its magnetic building blocks are strongly
fluctuating Cu tetrahedra. These spawn a continuum theory with a skyrmionic
texture that agrees well with reported experiments. It also brings to light a
decay of skyrmions into half-skyrmions in a specific temperature and magnetic
field range. The theoretical multiscale approach explains the strong
renormalization of the local moments and predicts further fingerprints of the
quantum origin of magnetic skyrmions that can be observed in CuOSeO,
like weakly dispersive high-energy excitations associated with the Cu
tetrahedra, a weak antiferromagnetic modulation of the primary ferrimagnetic
order, and a fractionalized skyrmion phase.Comment: 5 pages, 3 figure
Metastable Voltage States of Coupled Josephson Junctions
We investigate a chain of capacitively coupled Josephson junctions in the
regime where the charging energy dominates over the Josephson coupling,
exploiting the analogy between this system and a multi-dimensional crystal. We
find that the current-voltage characteristic of the current-driven chain has a
staircase shape, beginning with an (insulating) non-zero voltage plateau at
small currents. This behavior differs qualitatively from that of a single
junction, which should show Bloch oscillations with vanishing dc voltage. The
simplest system where this effect can be observed consists of three grains
connected by two junctions. The theory explains the results of recent
experiments on Josephson junction arrays.Comment: 5 pages, 4 figures include
Swinging and tumbling of elastic capsules in shear flow
The deformation of an elastic micro-capsule in an infinite shear flow is
studied numerically using a spectral method. The shape of the capsule and the
hydrodynamic flow field are expanded into smooth basis functions. Analytic
expressions for the derivative of the basis functions permit the evaluation of
elastic and hydrodynamic stresses and bending forces at specified grid points
in the membrane. Compared to methods employing a triangulation scheme, this
method has the advantage that the resulting capsule shapes are automatically
smooth, and few modes are needed to describe the deformation accurately.
Computations are performed for capsules both with spherical and ellipsoidal
unstressed reference shape. Results for small deformations of initially
spherical capsules coincide with analytic predictions. For initially
ellipsoidal capsules, recent approximative theories predict stable oscillations
of the tank-treading inclination angle, and a transition to tumbling at low
shear rate. Both phenomena have also been observed experimentally. Using our
numerical approach we could reproduce both the oscillations and the transition
to tumbling. The full phase diagram for varying shear rate and viscosity ratio
is explored. While the numerically obtained phase diagram qualitatively agrees
with the theory, intermittent behaviour could not be observed within our
simulation time. Our results suggest that initial tumbling motion is only
transient in this region of the phase diagram.Comment: 20 pages, 7 figure
Monte Carlo Comparisons to a Cryogenic Dark Matter Search Detector with low Transition-Edge-Sensor Transition Temperature
We present results on phonon quasidiffusion and Transition Edge Sensor (TES)
studies in a large, 3 inch diameter, 1 inch thick [100] high purity germanium
crystal, cooled to 50 mK in the vacuum of a dilution refrigerator, and exposed
with 59.5 keV gamma-rays from an Am-241 calibration source. We compare
calibration data with results from a Monte Carlo which includes phonon
quasidiffusion and the generation of phonons created by charge carriers as they
are drifted across the detector by ionization readout channels. The phonon
energy is then parsed into TES based phonon readout channels and input into a
TES simulator
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