1,026 research outputs found
Managing Uncertain Complex Events in Web of Things Applications
A critical issue in the Web of Things (WoT) is the need to process and analyze the interactions of Web-interconnected real-world
objects. Complex Event Processing (CEP) is a powerful technology for analyzing streams of information about real-time distributed events, coming from different sources, and for extracting conclusions from them. However, in many situations these events are not free from uncertainty, due to either unreliable data sources and networks, measurement uncertainty, or to the inability to determine whether an event has actually happened or not. This short research paper discusses how CEP systems
can incorporate different kinds of uncertainty, both in the events and in the rules. A case study is used to validate the proposal, and we discuss the benefits and limitations of this CEP extension.Universidad de Málaga. Campus de Excelencia Internacional AndalucÃa Tech
An Adaptive Fast Multipole Boundary Element Method for Poisson−Boltzmann Electrostatics
The numerical solution of the Poisson−Boltzmann (PB) equation is a useful but a computationally demanding tool for studying electrostatic solvation effects in chemical and biomolecular systems. Recently, we have described a boundary integral equation-based PB solver accelerated by a new version of the fast multipole method (FMM). The overall algorithm shows an order N complexity in both the computational cost and memory usage. Here, we present an updated version of the solver by using an adaptive FMM for accelerating the convolution type matrix-vector multiplications. The adaptive algorithm, when compared to our previous nonadaptive one, not only significantly improves the performance of the overall memory usage but also remarkably speeds the calculation because of an improved load balancing between the local- and far-field calculations. We have also implemented a node-patch discretization scheme that leads to a reduction of unknowns by a factor of 2 relative to the constant element method without sacrificing accuracy. As a result of these improvements, the new solver makes the PB calculation truly feasible for large-scale biomolecular systems such as a 30S ribosome molecule even on a typical 2008 desktop computer
Two Modes of Magnetization Switching in a Simulated Iron Nanopillar in an Obliquely Oriented Field
Finite-temperature micromagnetics simulations are employed to study the
magnetization-switching dynamics driven by a field applied at an angle to the
long axis of an iron nanopillar. A bi-modal distribution in the switching times
is observed, and evidence for two competing modes of magnetization-switching
dynamics is presented. For the conditions studied here, temperature K
and the reversal field 3160 Oe at an angle of 75 to the long axis,
approximately 70% of the switches involve unstable decay (no free-energy
barrier) and 30% involve metastable decay (a free-energy barrier is crossed).
The latter are indistinguishable from switches which are constrained to start
at a metastable free-energy minimum. Competition between unstable and
metastable decay could greatly complicate applications involving magnetization
switches near the coercive field.Comment: 19 pages, 7 figure
Stochastic Cutoff Method for Long-Range Interacting Systems
A new Monte-Carlo method for long-range interacting systems is presented.
This method consists of eliminating interactions stochastically with the
detailed balance condition satisfied. When a pairwise interaction of a
-particle system decreases with the distance as ,
computational time per one Monte Carlo step is for
and for , where is the spatial
dimension. We apply the method to a two-dimensional magnetic dipolar system.
The method enables us to treat a huge system of spins with reasonable
computational time, and reproduces a circular order originated from long-range
dipolar interactions.Comment: 18 pages, 9 figures, 1 figure and 1 reference are adde
Norbin ablation results in defective adult hippocampal neurogenesis and depressive-like behavior in mice
Adult neurogenesis in the hippocampus subgranular zone is associated with the etiology and treatment efficiency of depression. Factors that affect adult hippocampal neurogenesis have been shown to contribute to the neuropathology of depression. Glutamate, the major excitatory neurotransmitter, plays a critical role in different aspects of neurogenesis. Of the eight metabotropic glutamate receptors (mGluRs), mGluR5 is the most highly expressed in neural stem cells. We previously identified Norbin as a positive regulator of mGluR5 and showed that its expression promotes neurite outgrowth. In this study, we investigated the role of Norbin in adult neurogenesis and depressive-like behaviors using Norbin-deficient mice. We found that Norbin deletion significantly reduced hippocampal neurogenesis; specifically, the loss of Norbin impaired the proliferation and maturation of newborn neurons without affecting cell-fate specification of neural stem cells/neural progenitor cells (NSCs/NPCs). Norbin is highly expressed in the granular neurons in the dentate gyrus of the hippocampus, but it is undetectable in NSCs/NPCs or immature neurons, suggesting that the effect of Norbin on neurogenesis is likely caused by a nonautonomous niche effect. In support of this hypothesis, we found that the expression of a cell-cell contact gene, Desmoplakin, is greatly reduced in Norbin-deletion mice. Moreover, Norbin-KO mice show an increased immobility in the forced-swim test and the tail-suspension test and reduced sucrose preference compared with wild-type controls. Taken together, these results show that Norbin is a regulator of adult hippocampal neurogenesis and that its deletion causes depressive-like behaviors
Coulomb Interactions via Local Dynamics: A Molecular--Dynamics Algorithm
We derive and describe in detail a recently proposed method for obtaining
Coulomb interactions as the potential of mean force between charges which are
dynamically coupled to a local electromagnetic field. We focus on the Molecular
Dynamics version of the method and show that it is intimately related to the
Car--Parrinello approach, while being equivalent to solving Maxwell's equations
with freely adjustable speed of light. Unphysical self--energies arise as a
result of the lattice interpolation of charges, and are corrected by a
subtraction scheme based on the exact lattice Green's function. The method can
be straightforwardly parallelized using standard domain decomposition. Some
preliminary benchmark results are presented.Comment: 8 figure
A trapped-ion local field probe
We introduce a measurement scheme that utilizes a single ion as a local field
probe. The ion is confined in a segmented Paul trap and shuttled around to
reach different probing sites. By the use of a single atom probe, it becomes
possible characterizing fields with spatial resolution of a few nm within an
extensive region of millimeters. We demonstrate the scheme by accurately
investigating the electric fields providing the confinement for the ion. For
this we present all theoretical and practical methods necessary to generate
these potentials. We find sub-percent agreement between measured and calculated
electric field values
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