2,685 research outputs found
Cellular automata on regular rooted trees
We study cellular automata on regular rooted trees. This includes the
characterization of sofic tree shifts in terms of unrestricted Rabin automata
and the decidability of the surjectivity problem for cellular automata between
sofic tree shifts
How unprovable is Rabin's decidability theorem?
We study the strength of set-theoretic axioms needed to prove Rabin's theorem
on the decidability of the MSO theory of the infinite binary tree. We first
show that the complementation theorem for tree automata, which forms the
technical core of typical proofs of Rabin's theorem, is equivalent over the
moderately strong second-order arithmetic theory to a
determinacy principle implied by the positional determinacy of all parity games
and implying the determinacy of all Gale-Stewart games given by boolean
combinations of sets. It follows that complementation for
tree automata is provable from - but not -comprehension.
We then use results due to MedSalem-Tanaka, M\"ollerfeld and
Heinatsch-M\"ollerfeld to prove that over -comprehension, the
complementation theorem for tree automata, decidability of the MSO theory of
the infinite binary tree, positional determinacy of parity games and
determinacy of Gale-Stewart games are all
equivalent. Moreover, these statements are equivalent to the
-reflection principle for -comprehension. It follows in
particular that Rabin's decidability theorem is not provable in
-comprehension.Comment: 21 page
Branching Ratios for The Radiometric Calibration of EUNIS-2012
The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket instrument is a two-channel imaging spectrograph that observes the solar corona and transition region with high spectral resolution and a rapid cadence made possible by unprecedented sensitivity. The upcoming flight will incorporate a new wavelength channel covering the range 524-630 Angstroms, the previously-flown 300-370 Angstroms channel, and the first flight demonstration of cooled active pixel sensor (APS) arrays. The new 524-630 Angstrom channel incorporates a Toroidal Varied Line Space (TVLS) grating coated with B4C/Ir, providing broad spectral coverage and a wide temperature range of 0.025 to 10 MK. Absolute radiometric calibration of the two channels is being performed using a hollow cathode discharge lamp and NIST-calibrated AXUV-100G photodiode. Laboratory observations of He I 584 Angstroms and He II 304 Angstroms provide absolute radiometric calibrations of the two channels at those two respective wavelengths by using the AXUV photodiode as a transfer standard. The spectral responsivity is being determined by observing line pairs with a common upper state in the spectra of Ne I-III and Ar II-III. Calculations of A-values for the observed branching ratios are in progress
Mass Mixing, the Fourth Generation, and the Kinematic Higgs Mechanism
We describe how to construct chiral fermion mass terms using Dirac-Kahler
(DK) spinors. Classical massive DK spinors are shown to be equivalent to four
generations of Dirac spinors with equal mass coupled to a background U(2,2)
gauge field. Quantization breaks U(2,2) to U(2)xU(2), lifts mass spectrum
degeneracy, and generates a non-trivial mass mixing matrix.Comment: 12 pages. No figures. Phys Lett B version. Minor typos fixe
Lagrangian generators of the Poincare gauge symmetries
We have systematically computed the generators of the symmetries arising in
Poincare gauge theory formulation of gravity, both in 2+1 and 3+1 dimensions.
This was done using a completely Lagrangian approach. The results are expected
to be valid in any dimensions, as seen through lifting the results of the 2+1
dimensional example into the 3+1 dimensional one.Comment: Latex2e, 15 pages, 1 figure; (v2) Appendix containing discussion on
applications of Lagrangian generators adde
Seiberg-Witten-type Maps for Currents and Energy-Momentum Tensors in Noncommutative Gauge Theories
We derive maps relating the currents and energy-momentum tensors in
noncommutative (NC) gauge theories with their commutative equivalents. Some
uses of these maps are discussed. Especially, in NC electrodynamics, we obtain
a generalization of the Lorentz force law. Also, the same map for anomalous
currents relates the Adler-Bell-Jackiw type NC covariant anomaly with the
standard commutative-theory anomaly. For the particular case of two dimensions,
we discuss the implications of these maps for the Sugawara-type energy-momentum
tensor.Comment: 14 pages, JHEP styl
Systematic review of the Exploration, Preparation, Implementation, Sustainment (EPIS) framework
Background: Effective implementation of evidence-based practices (EBPs) remains a significant challenge. Numerous existing models and frameworks identify key factors and processes to facilitate implementation. However, there is a need to better understand how individual models and frameworks are applied in research projects, how they can support the implementation process, and how they might advance implementation science. This systematic review examines and describes the research application of a widely used implementation framework, the Exploration, Preparation, Implementation, Sustainment (EPIS) framework. Methods: A systematic literature review was performed to identify and evaluate the use of the EPIS framework in implementation efforts. Citation searches in PubMed, Scopus, PsycINFO, ERIC, Web of Science, Social Sciences Index, and Google Scholar databases were undertaken. Data extraction included the objective, language, country, setting, sector, EBP, study design, methodology, level(s) of data collection, unit(s) of analysis, use of EPIS (i.e., purpose), implementation factors and processes, EPIS stages, implementation strategy, implementation outcomes, and overall depth of EPIS use (rated on a 1-5 scale). Results: In total, 762 full-text articles were screened by four reviewers, resulting in inclusion of 67 articles, representing 49 unique research projects. All included projects were conducted in public sector settings. The majority of projects (73%) investigated the implementation of a specific EBP. The majority of projects (90%) examined inner context factors, 57% examined outer context factors, 37% examined innovation factors, and 31% bridging factors (i.e., factors that cross or link the outer system and inner organizational context). On average, projects measured EPIS factors across two of the EPIS phases (M = 2.02), with the most frequent phase being Implementation (73%). On average, the overall depth of EPIS inclusion was moderate (2.8 out of 5). Conclusion: This systematic review enumerated multiple settings and ways the EPIS framework has been applied in implementation research projects, and summarized promising characteristics and strengths of the framework, illustrated with examples. Recommendations for future use include more precise operationalization of factors, increased depth and breadth of application, development of aligned measures, and broadening of user networks. Additional resources supporting the operationalization of EPIS are available
The Spectrum of the 4-Generation Dirac-Kaehler Extension of the SM
We compute the mass spectrum of the fermionic sector of the Dirac-Kaehler
extension of the SM (DK-SM) by showing that there exists a Bogoliubov
transformation that transforms the DK-SM into a flavor U(4) extension of the SM
(SM-4) with a particular choice of masses and mixing textures. Mass relations
of the model allow determination of masses of the 4th generation. Tree level
prediction for the mass of the 4th charged lepton is 370 GeV. The model selects
the normal hierarchy for neutrino masses and reproduces naturally the near
tri-bimaximal and quark mixing textures. The electron neutrino and the 4th
neutrino masses are related via a see-saw-like mechanism.Comment: 14 pages. Phys Lett B versio
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