10,362 research outputs found
Kinetics of the long-range spherical model
The kinetic spherical model with long-range interactions is studied after a
quench to or to . For the two-time response and correlation
functions of the order-parameter as well as for composite fields such as the
energy density, the ageing exponents and the corresponding scaling functions
are derived. The results are compared to the predictions which follow from
local scale-invariance.Comment: added "fluctuation-dissipation ratios"; fixed typo
Cement Embolization into the Vena Cava and Pulmonal Arteries After Vertebroplasty: Interdisciplinary Management
AbstractPurposeTo report interdisciplinary management in a case of cement embolization into the inferior vena cava and peripheral pulmonary arteries after percutaneous vertebroplasty.Case reportA 50-year-old female patient with an osteoporotic compression fracture of the second lumbar vertebra underwent percutaneous vertebroplasty with polymethylmetaacrylate. Thereafter, CT scanning revealed small asymptomatic cement emboli in peripheral pulmonary arteries, along with a hook-shaped cement fragment in the inferior vena cava. Due to the risk that the large cement fragment could migrate to the pulmonary arteries and cause serious complications, they were retrieved from the inferior vena cava by an endovascular technique and extracted through a surgical groin incision. The patient received anticoagulant treatment for 3 months and is free of complaints after 1 year.ConclusionThis case shows that this rare complication following vertebroplasty can be successfully managed with an interdisciplinary approach
Desensitizing Inflation from the Planck Scale
A new mechanism to control Planck-scale corrections to the inflationary eta
parameter is proposed. A common approach to the eta problem is to impose a
shift symmetry on the inflaton field. However, this symmetry has to remain
unbroken by Planck-scale effects, which is a rather strong requirement on
possible ultraviolet completions of the theory. In this paper, we show that the
breaking of the shift symmetry by Planck-scale corrections can be
systematically suppressed if the inflaton field interacts with a conformal
sector. The inflaton then receives an anomalous dimension in the conformal
field theory, which leads to sequestering of all dangerous high-energy
corrections. We analyze a number of models where the mechanism can be seen in
action. In our most detailed example we compute the exact anomalous dimensions
via a-maximization and show that the eta problem can be solved using only
weakly-coupled physics.Comment: 34 pages, 3 figures
Simple threshold rules solve explore/exploit tradeâoffs in a resource accumulation search task
How, and how well, do people switch between exploration and exploitation to search for and accumulate resources? We study the decision processes underlying such exploration/exploitation tradeâoffs using a novel card selection task that captures the common situation of searching among multiple resources (e.g., jobs) that can be exploited without depleting. With experience, participants learn to switch appropriately between exploration and exploitation and approach optimal performance. We model participants' behavior on this task with random, threshold, and sampling strategies, and find that a linear decreasing threshold rule best fits participants' results. Further evidence that participants use decreasing thresholdâbased strategies comes from reaction time differences between exploration and exploitation; however, participants themselves report nonâdecreasing thresholds. Decreasing threshold strategies that âfrontâloadâ exploration and switch quickly to exploitation are particularly effective in resource accumulation tasks, in contrast to optimal stopping problems like the Secretary Problem requiring longer exploration
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Generation of multi-modal dialogue for a net environment
In this paper an architecture and special purpose markup language for simulated affective face-to-face communication is presented. In systems based on this architecture, users will be able to watch embodied conversational agents interact with each other in virtual locations on the internet. The markup language, or Rich Representation Language (RRL), has been designed to provide an integrated representation of speech, gesture, posture and facial animation
Magnetic order in double-layer manganites (La(1-z)Pr(z))1.2Sr1.8Mn2O7: intrinsic properties and role of the intergrowths
We report on an investigation of the double-layer manganite series
(La(1-z)Pr(z))1.2Sr1.8Mn2O7 (0 <= z <= 1), carried out on single crystals by
means of both macroscopic magnetometry and local probes of magnetism (muSR,
55Mn NMR). Muons and NMR demonstrate an antiferromagnetically ordered ground
state at non-ferromagnetic compositions (z >= 0.6), while more moderate Pr
substitutions (0.2 <= z <= 0.4) induce a spin reorientation transition within
the ferromagnetic phase.
A large magnetic susceptibility is detected at {Tc,TN} < T < 250K at all
compositions. From 55Mn NMR spectroscopy, such a response is unambiguously
assigned to the intergrowth of a ferromagnetic pseudocubic phase
(La(1-z)Pr(z))(1-x)Sr(x)MnO3, with an overall volume fraction estimated as
0.5-0.7% from magnetometry. Evidence is provided for the coupling of the
magnetic moments of these inclusions with the magnetic moments of the
surrounding (La(1-z)Pr(z))1.2Sr1.8Mn2O7 phase, as in the case of finely
dispersed impurities. We argue that the ubiquitous intergrowth phase may play a
role in the marked first-order character of the magnetic transition and the
metamagnetic properties above Tc reported for double-layer manganites.Comment: 11 pages, 9 figures. Submitted to Phys. Rev.
Persistent photovoltage in methylammonium lead iodide perovskite solar cells
Open circuit voltage decay measurements are performed on methylammonium lead
iodide (CH3NH3PbI3) perovskite solar cells to investigate the charge carrier
recombination dynamics. The measurements are compared to the two reference
polymer-fullerene bulk heterojunction solar cells based on P3HT:PC60BM and
PTB7:PC70BM blends. In the perovskite devices, two very different time domains
of the voltage decay are found, with a first drop on a short time scale that is
similar to the organic solar cells. However, two major differences are also
observed. 65-70% of the maximum photovoltage persists on much longer
timescales, and the recombination dynamics are dependent on the illumination
intensity.Comment: 5 pages, 3 figure
Ageing in bosonic particle-reaction models with long-range transport
Ageing in systems without detailed balance is studied in bosonic contact and
pair-contact processes with Levy diffusion. In the ageing regime, the dynamical
scaling of the two-time correlation function and two-time response function is
found and analysed. Exact results for non-equilibrium exponents and scaling
functions are derived. The behaviour of the fluctuation-dissipation ratio is
analysed. A passage time from the quasi-stationary regime to the ageing regime
is defined, in qualitative agreement with kinetic spherical models and p-spin
spherical glasses.Comment: Latex2e, 24 pages, with 9 figures include
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