4,669 research outputs found
Analysing Magnetism Using Scanning SQUID Microscopy
Scanning superconducting quantum interference device microscopy (SSM) is a
scanning probe technique that images local magnetic flux, which allows for
mapping of magnetic fields with high field and spatial accuracy. Many studies
involving SSM have been published in the last decades, using SSM to make
qualitative statements about magnetism. However, quantitative analysis using
SSM has received less attention. In this work, we discuss several aspects of
interpreting SSM images and methods to improve quantitative analysis. First, we
analyse the spatial resolution and how it depends on several factors. Second,
we discuss the analysis of SSM scans and the information obtained from the SSM
data. Using simulations, we show how signals evolve as a function of changing
scan height, SQUID loop size, magnetization strength and orientation. We also
investigated 2-dimensional autocorrelation analysis to extract information
about the size, shape and symmetry of magnetic features. Finally, we provide an
outlook on possible future applications and improvements.Comment: 16 pages, 10 figure
Reconstructing phylogenetic level-1 networks from nondense binet and trinet sets
Binets and trinets are phylogenetic networks with two and three leaves, respectively. Here we consider the problem of deciding if there exists a binary level-1 phylogenetic network displaying a given set T of binary binets or trinets over a taxon set X, and constructing such a network whenever it exists. We show that this is NP-hard for trinets but polynomial-time solvable for binets. Moreover, we show that the problem is still polynomial-time solvable for inputs consisting of binets and trinets as long as the cycles in the trinets have size three. Finally, we present an O(3^{|X|} poly(|X|)) time algorithm for general sets of binets and trinets. The latter two algorithms generalise to instances containing level-1 networks with arbitrarily many leaves, and thus provide some of the first supernetwork algorithms for computing networks from a set of rooted 1 phylogenetic networks
Considerations for an Ac Dipole for the LHC
Following successful experience at the BNL AGS, FNAL Tevatron, and CERN SPS,
an AC Dipole will be adopted at the LHC for rapid measurements of ring optics.
This paper describes some of the parameters of the AC dipole for the LHC,
scaling from performance of the FNAL and BNL devices.Comment: proceedings of the 2007 Particle Accelerator Conferenc
FliPpr: A Prettier Invertible Printing System
When implementing a programming language, we often write
a parser and a pretty-printer. However, manually writing both programs
is not only tedious but also error-prone; it may happen that a pretty-printed
result is not correctly parsed. In this paper, we propose FliPpr,
which is a program transformation system that uses program inversion
to produce a CFG parser from a pretty-printer. This novel approach
has the advantages of fine-grained control over pretty-printing, and easy
reuse of existing efficient pretty-printer and parser implementations
System data communication structures for active-control transport aircraft, volume 2
The application of communication structures to advanced transport aircraft are addressed. First, a set of avionic functional requirements is established, and a baseline set of avionics equipment is defined that will meet the requirements. Three alternative configurations for this equipment are then identified that represent the evolution toward more dispersed systems. Candidate communication structures are proposed for each system configuration, and these are compared using trade off analyses; these analyses emphasize reliability but also address complexity. Multiplex buses are recognized as the likely near term choice with mesh networks being desirable for advanced, highly dispersed systems
System data communication structures for active-control transport aircraft, volume 1
Candidate data communication techniques are identified, including dedicated links, local buses, broadcast buses, multiplex buses, and mesh networks. The design methodology for mesh networks is then discussed, including network topology and node architecture. Several concepts of power distribution are reviewed, including current limiting and mesh networks for power. The technology issues of packaging, transmission media, and lightning are addressed, and, finally, the analysis tools developed to aid in the communication design process are described. There are special tools to analyze the reliability and connectivity of networks and more general reliability analysis tools for all types of systems
A critical analysis of the hydrino model
Recently, spectroscopic and calorimetric observations of hydrogen plasmas and
chemical reactions with them have been interpreted as evidence for the
existence of electronic states of the hydrogen atom with a binding energy of
more than 13.6 eV. The theoretical basis for such states, that have been dubbed
hydrinos, is investigated. We discuss both, the novel deterministic model of
the hydrogen atom, in which the existence of hydrinos was predicted, and
standard quantum mechanics. Severe inconsistencies in the deterministic model
are pointed out and the incompatibility of hydrino states with quantum
mechanics is reviewed.Comment: 9 page
Practical Evaluation of Lempel-Ziv-78 and Lempel-Ziv-Welch Tries
We present the first thorough practical study of the Lempel-Ziv-78 and the
Lempel-Ziv-Welch computation based on trie data structures. With a careful
selection of trie representations we can beat well-tuned popular trie data
structures like Judy, m-Bonsai or Cedar
Plants lacking the main light-harvesting complex retain photosystem II macro-organization
Photosystem II (PSII) is a key component of photosynthesis, the process of converting sunlight into the chemical energy of life. In plant cells, it forms a unique oligomeric macrostructure in membranes of the chloroplasts. Several light-harvesting antenna complexes are organized precisely in the PSII macrostructure—the major trimeric complexes (LHCII) that bind 70% of PSII chlorophyll and three minor monomeric complexes—which together form PSII supercomplexes. The antenna complexes are essential for collecting sunlight and regulating photosynthesis, but the relationship between these functions and their molecular architecture is unresolved. Here we report that antisense Arabidopsis plants lacking the proteins that form LHCII trimers have PSII supercomplexes with almost identical abundance and structure to those found in wild-type plants. The place of LHCII is taken by a normally minor and monomeric complex, CP26, which is synthesized in large amounts and organized into trimers. Trimerization is clearly not a specific attribute of LHCII. Our results highlight the importance of the PSII macrostructure: in the absence of one of its main components, another protein is recruited to allow it to assemble and function
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