198,468 research outputs found
Totally Symmetric Kekule Structures in Fullerene Graphs with Ten or More Symmetries
No full textGraph theoretic fullerenes are designed to model large carbon molecules: each vertex represents a carbon atom and the edges represent chemical bonds. A totally symmetric Kekulé structure in a fullerene is a set of independent edges which is fixed by all symmetries of the fullerene. It was suggested in a paper by S. J. Austin, J. Baker, P. W. Fowler, D. E. Manolopoulos and in a paper by K. M. Rogers and P. W. Fowler that molecules with totally symmetric Kekulé structures could have special physical and chemical properties. Starting from a catalog given by J.E.Graver, we study all graph theoretic fullerenes with at least ten symmetries and we establish exactly which of them have at least one totally symmetric Kekulé structure.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Totally Symmetric Kekule Structures in Fullerene Graphs with Ten or More Symmetries
No full textGraph theoretic fullerenes are designed to model large carbon molecules: each vertex represents a carbon atom and the edges represent chemical bonds. A totally symmetric Kekulé structure in a fullerene is a set of independent edges which is fixed by all symmetries of the fullerene.
It was suggested in a paper by S. J. Austin, J. Baker, P. W. Fowler, D. E. Manolopoulos and in a paper by K. M. Rogers and P. W. Fowler that molecules with totally symmetric Kekulé structures could have special physical and chemical properties. Starting from a catalog given by J.E.Graver, we study all graph theoretic fullerenes with at least ten symmetries and we establish exactly which of them have
at least one totally symmetric Kekulé structure
Incipit rationale diuino[rum] officio[rum] p[er] [...] Guilhelmu[m] dura[n]ti.
No full textImpressum uit colofon: kl. MaijHerkomst: Obiit Petrus de Colonia pastor ecclesie sancte Gertrudis et legavit presens librum domino Henrico Luyten ; Anno 1529 obiit prefatus Henricus Luyten et legavit ... Reniro Bogaerts vicecurato ... eodem anno testamentarie ; Anno 1537 nov 19 obiit dominus Reynerus Bogaerts qui legavit in testamentum domino Petro hunc codicem ; Anno 1575 jan obiit dominus Petrus de Ville vir religioni deditus ; De Longueval ; Bibliothecae Augustinianae Teneraemundae [Augustijnen Dendermonde] 1618 fr. Ignatius De Dijckere prior 1686 ; Stempel Augustijnen AntwerpenBMC: Catalogue of books printed in the XVth century now in the British Museum II 418bGesamtkatalog der Wiegendrucke ; 9121Machiels, J. Catalogus van de boeken gedrukt vóór 1600 ; D 390Polain, M.-L. Catalogue des livres imprimé au 15e siècle ... ; 1376Europeana-GoogleBook
Invariant Kekulé structures in fullerene graphs
No full textFullerene graphs are trivalent plane graphs with only hexagonal and pentagonal faces. They are often used to model large carbon molecules: each vertex represents a carbon atom and the edges represent chemical bonds. A totally symmetric Kekulé structure in a fullerene graph is a set of independent edges which is fixed by all symmetries of the fullerene and molecules with totally symmetric Kekulé structures could have special physical and chemical properties, as suggested in [1] and [8]. All fullerenes with at least ten symmetries were studied in [4] and a complete catalog was given in [5]. Starting from this catalog in [2] we established exactly which of them have at least one totally symmetric Kekulé structure
Groundedness in Logics With a Fixpoint Semantics
No full textIn the field of knowledge representation and reasoning, many different logics are
developed. Often, these logics exhibit striking similarities, either because they
emerged from related ideas, or because they use similar underlying fundamental
principles. Approximation fixpoint theory (AFT) is an abstract algebraical
unifying framework that aims at exposing these principles by formalising them
in lattice theory. It has been successfully applied to unify all common semantics
of logic programs, autoepistemic logic, default logic, and more recently Dung’s
argumentation frameworks and abstract dialectical frameworks.
In this dissertation, we extend approximation fixpoint theory to expose more
underlying principles common to the aforementioned logics. In these domains,
researchers have made use of a similar intuition: that facts (or models) can be
derived from the ground up. They typically phrase this intuition by saying, e.g.,
that the facts should be grounded, or that they should not be unfounded, or
that they should be supported by cycle-free arguments. In different domains,
semantics that allow ungrounded models have received a lot of criticism. In logic
programming for example, this was the case for Clark’s completion semantics,
which was later improved by perfect model semantics, stable semantics and
well-founded semantics. In autoepistemic logic, a similar evolution happened:
Moore’s expansion semantics turned out to allow self-supporting models; this
resulted in the development of many different semantics in attempts to get rid
of this erroneous behaviour.
In the first part of this dissertation, we formalise groundedness in approximation
fixpoint theory. We study how groundedness relates to other concepts and
fixpoints studied in AFT. We apply our abstract theory to the aforementioned
domains: we show that our notion of groundedness indeed captures the intuitions
that existed in these domains and study complexity of reasoning with grounded
models. We study which existing semantics are grounded and which are not.
For example, for logic programming, we find that Clark’s completion semantics
(indeed) is not grounded, while stable and well-founded semantics are grounded. We show that the well-founded model is not just any grounded model: it is the
least precise partial grounded model.
In the second part of this thesis we define a class of autoepistemic theories for
which it is informally clear how to construct the intended model. Unfortunately,
despite previous claims that the well-founded semantics captures the meaning
of autoepistemic theories very well (e.g., because of its constructive nature),
the well-founded semantics fails to identify this model. In order to overcome
this limitation, we propose, algebraically, a new constructive semantics based
on the notion of groundedness. Our new construction refines the well-founded
model construction and succeeds in identifying the intended model for the class
of motivating examples. Furthermore, we show that for this class of examples,
our novel construction constructs the unique grounded fixpoint.
Summarised, in this dissertation, we continue the work on approximation fixpoint
theory by identifying novel concepts occurring in all of the application domains
and by refining existing semantics to better capture the intended meaning of a
class of theories
Optical leaky fin waveguide for long-range optical antennas on high-index contrast photonic circuit platforms
No full textLong-distance light detection and ranging (LiDAR) applications require an aperture size in the order of 30 mm to project 200–300 m. To generate such collimated Gaussian beams from the surface of a chip, this work presents a novel waveguide antenna concept, which we call an “optical leaky fin antenna,” consisting of a tapered waveguide with a narrow vertical “fin” on top. The proposed structure (operating around =1.55 μm) overcomes fundamental fabrication challenges encountered in weak apodized gratings, the conventional method to create an off-chip wide Gaussian beam from a waveguide chip. We explore the design space of the antenna by scanning the relevant cross section parameters in a mode solver, and their sensitivity is examined. We also investigate the dispersion of the emission pattern and angle with the wavelength. The simulated design space is then used to construct and simulate an optical antenna to emit a collimated target intensity profile. Results show inherent robustness to crucial design parameters and indicate good scalability of the design. Possibilities and challenges to fabricate this device concept are also discussed. This novel antenna concept illustrates the possibility to integrate long optical antennas required for long-range solid-state LiDAR systems on a high-index contrast platform with a scalable fabrication method
Marie Stuart au château de Lochleven, opérette de salon, en un acte / paroles de M. Bogaerts ; musique de J. M. Duprato...
No full textDr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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