6,720 research outputs found
Aquarium dermatitis: Cercarial dermatitis in an aquarist
A 33-year-old man presented with very itchy red papules on the back of his hands and forearms. These papules appeared about 90 min after he had cleaned his aquarium in which he kept native fish and watersnails. He had obtained the watersnails some weeks before from a nearby pond. Examination of water from the aquarium revealed cercariae. The clinical diagnosis of cercarial dermatitis was corroborated. Cercarial dermatitis has repeatedly been seen in swimmers but not in aquarists keeping fish in a home aquarium
Anyonic statistics and large horizon diffeomorphisms for Loop Quantum Gravity Black Holes
We investigate the role played by large diffeomorphisms of quantum Isolated
Horizons for the statistics of LQG Black Holes by means of their relation to
the braid group. To this aim the symmetries of Chern-Simons theory are
recapitulated with particular regard to the aforementioned type of
diffeomorphisms. For the punctured spherical horizon, these are elements of the
mapping class group of , which is almost isomorphic to a corresponding
braid group on this particular manifold. The mutual exchange of quantum
entities in two dimensions is achieved by the braid group, rendering the
statistics anyonic. With this we argue that the quantum Isolated Horizon model
of LQG based on -Chern-Simons theory explicitly exhibits non-abelian
anyonic statistics. In this way a connection to the theory behind the
fractional quantum Hall effect and that of topological quantum computation is
established, where non-abelian anyons play a significant role.Comment: 20 pages, 8 figures, closest to published versio
Efficient algorithm to study interconnected networks
Interconnected networks have been shown to be much more vulnerable to random
and targeted failures than isolated ones, raising several interesting questions
regarding the identification and mitigation of their risk. The paradigm to
address these questions is the percolation model, where the resilience of the
system is quantified by the dependence of the size of the largest cluster on
the number of failures. Numerically, the major challenge is the identification
of this cluster and the calculation of its size. Here, we propose an efficient
algorithm to tackle this problem. We show that the algorithm scales as O(N log
N), where N is the number of nodes in the network, a significant improvement
compared to O(N^2) for a greedy algorithm, what permits studying much larger
networks. Our new strategy can be applied to any network topology and
distribution of interdependencies, as well as any sequence of failures.Comment: 5 pages, 6 figure
Risk-Averse Model Predictive Operation Control of Islanded Microgrids
In this paper we present a risk-averse model predictive control (MPC) scheme
for the operation of islanded microgrids with very high share of renewable
energy sources. The proposed scheme mitigates the effect of errors in the
determination of the probability distribution of renewable infeed and load.
This allows to use less complex and less accurate forecasting methods and to
formulate low-dimensional scenario-based optimisation problems which are
suitable for control applications. Additionally, the designer may trade
performance for safety by interpolating between the conventional stochastic and
worst-case MPC formulations. The presented risk-averse MPC problem is
formulated as a mixed-integer quadratically-constrained quadratic problem and
its favourable characteristics are demonstrated in a case study. This includes
a sensitivity analysis that illustrates the robustness to load and renewable
power prediction errors
Hierarchical distributed scenario-based model predictive control of interconnected microgrids
Microgrids are autonomous clusters of generators, storage units and loads.
Special requirements arise in interconnected operation: control schemes that do
not require individual microgrids to disclose data about their internal
structure and operating objectives are preferred for privacy reasons. Moreover,
a safe and economically meaningful operation shall be achieved in presence of
uncertain load and weather-dependent availability of renewable infeed. In this
paper, we propose a distributed model predictive control approach that
satisfies these requirements. Specifically, we demonstrate that costs and
safety of supply can be improved through a scenario-based stochastic control
scheme. In a numerical case study, our approach is compared to a certainty
equivalence scheme. The results illustrate the improved safety and reduced
runtime costs as well as sufficiently fast convergence
Separable mechanisms underlying global feature-based attention
Feature-based attention is known to operate in a spatially global manner, in that the selection of attended features is not bound to the spatial focus of attention. Here we used electromagnetic recordings in human observers to characterize the spatiotemporal signature of such global selection of an orientation feature. Observers performed a simple orientation-discrimination task while ignoring task-irrelevant orientation probes outside the focus of attention. We observed that global feature-based selection, indexed by the brain response to unattended orientation probes, is composed of separable functional components. One such component reflects global selection based on the similarity of the probe with task-relevant orientation values ("template matching"), which is followed by a component reflecting selection based on the similarity of the probe with the orientation value under discrimination in the focus of attention ("discrimination matching"). Importantly, template matching occurs at similar to 150 ms after stimulus onset, similar to 80 ms before the onset of discrimination matching. Moreover, source activity underlying template matching and discrimination matching was found to originate from ventral extrastriate cortex, with the former being generated in more anterolateral and the latter in more posteromedial parts, suggesting template matching to occur in visual cortex higher up in the visual processing hierarchy than discrimination matching. We take these observations to indicate that the population-level signature of global feature-based selection reflects a sequence of hierarchically ordered operations in extrastriate visual cortex, in which the selection based on task relevance has temporal priority over the selection based on the sensory similarity between input representations
Isolation and Molecular Characterization of a Novel Cytopathogenic Paramyxovirus from Tree Shrews
AbstractA cytopathic infectious agent was isolated from the kidneys of an apparently healthy tree shrew (Tupaia belangeri) that had been captured in the area around Bangkok. The infectivity was propagated in Tupaia fibroblast and kidney cell cultures. Paramyxovirus-like pleomorphic enveloped particles and helical nucleocapsids were observed by electron microscopy and accordingly the infectious agent was termed Tupaia paramyxovirus (TPMV). However, no serological cross-reactions were detected between TPMV and known paramyxoviruses. For the molecular characterization of TPMV an experimental strategy that allows the random-primed synthesis of relatively large cDNA molecules from viral genomic RNA was applied. Nucleotide sequence analysis of a TPMV-specific cDNA fragment (1544 bp) revealed two nonoverlapping partial open reading frames corresponding to paramyxoviral N and P transcription units. Using modified rapid amplification of cDNA ends techniques, a substantial contiguous portion of the viral genome (4065 nt) was elucidated including the complete N and P/V/C genes. The coding strategy of TPMV as well as significant amino acid sequence homologies clearly indicates an evolutionary relationship between TPMV and members of the genus Morbillivirus. Highest homologies were detected between TPMV and Hendra virus (equine morbillivirus), which recently emerged in Australia, causing outbreaks of fatal respiratory and neurological disease in horses and humans
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