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Diagrammatic Representation (diagrammatic + representation)

Distribution by Scientific Domains
Chemistry40%

Selected Abstracts

Diagrammatic Representation in Geometry

DIALECTICA, Issue 4 2006
Dennis Potter
In this paper I offer a theory about the nature of diagrammatic representation in geometry. On my view, diagrammatic representaiton differs from pictorial representation in that neither the resemblance between the diagram and its object nor the experience of such a resemblance plays an essential role. Instead, the diagrammatic representation is arises from the role the components of the diagram play in a diagramatic practice that allows us to draws inferences based on them about the ojbects they represent. [source]

How many-body perturbation theory (MBPT) has changed quantum chemistry

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 15 2009
Werner KutzelniggArticle first published online: 26 AUG 200
Abstract The history of many-body perturbation theory (MBPT) and its impact on Quantum Chemistry is reviewed, starting with Brueckner's conjecture of a linked-cluster expansion and the time-dependent derivation by Goldstone of such an expansion. A central part of this article is the time-independent formulation of quantum chemistry in Fock space and its diagrammatic representation including the particle-hole picture and the inversion of a commutator. The results of the time-independent derivation of MBPT are compared with those of Goldstone. It is analyzed which ingredients of Goldstone's approach are decisive. The connected diagram theorem is derived both in a constructive way based on a Lie-algebraic formulation and a nonconstructive way making use of the separation theorem. It is discussed why the Goldstone derivation starting from a unitary time-evolution operator, ends up with a wave operator in intermediate normalization. The Møller,Plesset perturbation expansions of Bartlett and Pople are compared. Examples of complete summations of certain classes of diagrams are discussed, for example, that which leads to the Bethe-Goldstone expansion. MBPT for energy differences is analyzed. The paper ends with recent developments and challenges, such as the generalization of normal ordering to arbitrary reference states, contracted Schrödinger k -particle equations and Brillouin conditions, and finally the Nakatsuji theorem and the Nooijen conjecture. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source]

Perspectives of data analysis of enzyme inhibition and activation, Part 1: Use of the three-dimensional Km, V,I coordinate system for data analysis of enzyme inhibition and activation

JOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 2 2009
Vladimir I. Krupyanko
Abstract The possibility of construction of the three-dimensional (unfolded and folded) Km, V,I rectangular coordinate systems convenient for vector representation of inhibited and activated enzymatic reactions as well as of a two-dimensional Km, V, scalar rectangular coordinate system convenient for diagrammatic representation of enzymatic reactions is considered. The perspectives of using the properties of the three-dimensional L vectors and their scalar L projections for data analysis of enzyme inhibition and activation are analyzed. © 2009 Wiley Periodicals, Inc. J Biochem Mol Toxicol 23:97,100, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20273 [source]

Electrifying diagrams for learning: principles for complex representational systems

COGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 6 2002
Peter C.-H.
Abstract Six characteristics of effective representational systems for conceptual learning in complex domains have been identified. Such representations should: (1) integrate levels of abstraction; (2) combine globally homogeneous with locally heterogeneous representation of concepts; (3) integrate alternative perspectives of the domain; (4) support malleable manipulation of expressions; (5) possess compact procedures; and (6) have uniform procedures. The characteristics were discovered by analysing and evaluating a novel diagrammatic representation that has been invented to support students' comprehension of electricity,AVOW diagrams (Amps, Volts, Ohms, Watts). A task analysis is presented that demonstrates that problem solving using a conventional algebraic approach demands more effort than AVOW diagrams. In an experiment comparing two groups of learners using the alternative approaches, the group using AVOW diagrams learned more than the group using equations and were better able to solve complex transfer problems and questions involving multiple constraints. Analysis of verbal protocols and work scratchings showed that the AVOW diagram group, in contrast to the equations group, acquired a coherently organised network of concepts, learnt effective problem solving procedures, and experienced more positive learning events. The six principles of effective representations were proposed on the basis of these findings. AVOW diagrams are Law Encoding Diagrams, a general class of representations that have been shown to support learning in other scientific domains. [source]