4,654 research outputs found
Conference on the Development of Fire-Resistant Aircraft Passenger Seats
Papers are presented dealing with the development of aircraft seats with the minimum fire risk. Criteria examined include: flame spread, heat release, and smoke and/or toxic fumes. Materials and performance specifications of all seat material options are provided
Electrons in the Earth's Outer Radiation Zone
Electrons in the earths outer radiation bel
Optimal condition to probe strong coupling of two-dimensional excitons and zero-dimensional cavity modes
The light-matter interaction associated with a two-dimensional excitonic transition coupled to a zero-dimensional photonic cavity is fundamentally different from cavity-coupled localized excitations in quantum dots or color centers, which have negligible spatial extent compared to the cavity-confined mode profile. We provide a succinct expression for calculating the light-matter interaction of a two-dimensional optical transition coupled to a zero-dimensional confined cavity mode. From this expression, we found there is an optimal spatial extent of the excitonic transition that maximizes such an interaction strength due to the competition between minimizing the excitonic envelope function area and maximizing the total integrated field. We also found that at near zero exciton-cavity detuning, the direct transmission efficiency of a waveguide-integrated cavity can be severely suppressed, which suggests performing experiments using a side-coupled cavity
Simplified multitarget tracking using the PHD filter for microscopic video data
The probability hypothesis density (PHD) filter from the theory of random finite sets is a well-known method for multitarget tracking. We present the Gaussian mixture (GM) and improved sequential Monte Carlo implementations of the PHD filter for visual tracking. These implementations are shown to provide advantages over previous PHD filter implementations on visual data by removing complications such as clustering and data association and also having beneficial computational characteristics. The GM-PHD filter is deployed on microscopic visual data to extract trajectories of free-swimming bacteria in order to analyze their motion. Using this method, a significantly larger number of tracks are obtained than was previously possible. This permits calculation of reliable distributions for parameters of bacterial motion. The PHD filter output was tested by checking agreement with a careful manual analysis. A comparison between the PHD filter and alternative tracking methods was carried out using simulated data, demonstrating superior performance by the PHD filter in a range of realistic scenarios
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Full meta objects for flexible geoprocessing workflows: profiling WPS or BPMN?
The design and execution of scientific workflows is an important and necessary function within many disciplines. In the geospatial community, workflows are used to generate and quality assure new spatial datasets based on sequences of processing steps or complex modelling. Using BPMN for representing these workflows allows stakeholders to discuss the scientific conceptual approach behind this modelling whilst also being able to execute its encoding in XML. Previous research has focused on developing frameworks, including a BPMN workflow engine, capable of orchestrating OGC Web Processing Services and thus enabling construction of interoperable workflows comprised of distributed resources. These could populate, for example, the GEOSS repository. However, to date, such work has focused on executing workflows with direct access to the pre-defined data inputs and outputs, with a lack of flexibility and efficiency in semantic interoperability or data management during composition and execution. This article suggests a meta-approach based on two possible configurations that enable workflow orchestration at a meta level using a direct coupling with a metadata catalogue. The designs of a Web Processing Service profile and of a BPMN profile are presented as potential approaches to abstract the data interchange between the processing steps of a workflow. The paper concludes with a discussion of how these approaches may be extended and how complete workflows might be registered and managed using catalogues services
IUPHAR-DB: An Expert-Curated, Peer-Reviewed Database of Receptors and Ion Channels
The International Union of Basic and Clinical Pharmacology database (IUPHAR-DB) integrates peer-reviewed pharmacological, chemical, genetic, functional and anatomical information on the 354 non-sensory G protein-coupled receptors (GPCRs), 71 ligand-gated ion channel subunits and 141 voltage-gated ion channel subunits encoded by the human, rat and mouse genomes. These genes represent the targets of about a third of currently approved drugs and are a major focus of drug discovery and development programs in the pharmaceutical industry. Individual gene pages provide a comprehensive description of the genes and their functions, with information on protein structure, ligands, expression patterns, signaling mechanisms, functional assays and biologically important receptor variants (e.g. single nucleotide polymorphisms and splice variants). The phenotypes resulting from altered gene expression (e.g. in genetically altered animals) and genetic mutations are described. Links are provided to bioinformatics resources such as NCBI RefSeq, OMIM, PubChem, human, rat and mouse genome databases. Recent developments include the addition of ligand-centered pages summarising information about unique ligand molecules in IUPHAR-DB. IUPHAR-DB represents a novel approach to biocuration because most data are provided through manual curation of published literature by a network of over 60 expert subcommittees coordinated by NC-IUPHAR. Data are referenced to the primary literature and linked to PubMed. The data are checked to ensure accuracy and consistency by the curators, added to the production server using custom-built submission tools and peer-reviewed by NC-IUPHAR, before being transferred to the public database. Data are reviewed and updated regularly (at least biennially). Other website features include comprehensive database search tools, online and downloadable gene lists and links to recent publications of interest to the field, such as reports on receptor-ligand pairings. The database is freely available at "http://www.iuphar-db.org":http://www.iuphar-db.org. Curators can be reached at curators [at] iuphar-db.org. We thank British Pharmacological Society, UNESCO (through the ICSU Grants Programme), Incyte, GlaxoSmithKline, Novartis, Servier and Wyeth for their support
A Number-Theoretic Error-Correcting Code
In this paper we describe a new error-correcting code (ECC) inspired by the
Naccache-Stern cryptosystem. While by far less efficient than Turbo codes, the
proposed ECC happens to be more efficient than some established ECCs for
certain sets of parameters. The new ECC adds an appendix to the message. The
appendix is the modular product of small primes representing the message bits.
The receiver recomputes the product and detects transmission errors using
modular division and lattice reduction
Dispersive coupling between MoSe2 and an integrated zero-dimensional nanocavity
Establishing a coherent interaction between a material resonance and an optical cavity is a necessary first step to study semiconductor quantum optics. Here we report on the signature of a coherent interaction between a two-dimensional excitonic transition in monolayer MoSe2 and a zero-dimensional, ultra-low mode volume, V∼ 2(λ/n)^3, on-chip photonic crystal nanocavity. This coherent interaction manifests as a dispersive shift of the cavity transmission spectrum, when the exciton-cavity detuning is decreased via temperature tuning. The exciton-cavity coupling is estimated to be about 6.5 meV, with a cooperativity of about 4.0 at 80 K, showing our material system is on the verge of strong coupling. The small mode-volume of the resonator is instrumental in reaching the strongly nonlinear regime, while on-chip cavities will help create a scalable quantum photonic platform
Charges and fields in a current-carrying wire
Charges and fields in a straight, infinite, cylindrical wire carrying a
steady current are determined in the rest frames of ions and electrons,
starting from the standard assumption that the net charge per unit length is
zero in the lattice frame and taking into account a self-induced pinch effect.
The analysis presented illustrates the mutual consistency of classical
electromagnetism and Special Relativity. Some consequences of the assumption
that the net charge per unit length is zero in the electrons frame are also
briefly discussed
Efficient implementation of selective recoupling in heteronuclear spin systems using Hadamard matrices
We present an efficient scheme which couples any designated pair of spins in
heteronuclear spin systems. The scheme is based on the existence of Hadamard
matrices. For a system of spins with pairwise coupling, the scheme
concatenates intervals of system evolution and uses at most pulses
where . Our results demonstrate that, in many systems, selective
recoupling is possible with linear overhead, contrary to common speculation
that exponential effort is always required.Comment: 7 pages, 4 figures, mypsfig2, revtex, submitted April 27, 199
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