scholarly journals Ring-Current Assessment of the Annulene-Within-an-Annulene Model for some Large Coupled Super-Ring Conjugated-Systems

2014 ◽  
Vol 87 (3) ◽  
pp. 221-232 ◽  
Author(s):  
Timothy K. Dickens ◽  
Roger B. Mallion
Keyword(s):  
Ring Current ◽  
Conjugated Systems ◽  
Current Assessment

Some graph-theoretical aspects of simple ring current calculations on conjugated systems

1975 ◽  
Vol 341 (1627) ◽  
pp. 429-449 ◽  
Keyword(s):  
Unitary Transformation ◽  
Ring Current ◽  
Spanning Trees ◽  
Molecular Graph ◽  
Current Concept ◽  
Close Correspondence ◽  
Conjugated Systems ◽  
Ring Currents ◽  
Secular Equations ◽  
Simple Connected Graph

In this paper we examine the simple theory of π -electron ring currents in conjugated systems (devised originally by London (1937) and extended by People (1958) and McWeeny (1958)), with particular reference to the topological or graph-theoretical aspects of it (all the necessary graph-theoretical ideas and terminology are explained in the text). There is a close correspondence between the adjacency matrix of the graph representing the σ-bond skeleton of the carbon atoms comprising a given conjugated system, and the secular equations which arise in the theory (a relation now well known to be common to all formalisms based on Hückel ‘topological’ molecular orbitals), but in addition we here emphasize that several other graph-theoretical ideas–notably those concerning circuits and spanning trees–specifically underlie the ring current concept. In this connexion, the question of whether any given molecular graph is semi-Hamiltonian or non-Hamiltonian is of prime importance, and it is pointed out that a unitary transformation originally proposed by McWeeny applies to semi-Hamiltonian molecular graphs, whereas one recently devised by Gayoso & Boucekkine can be applied to any simple, connected graph–as also can an explicit ring current formula (based on the London–McWeeny theory) just published by the present author. These ideas are illustrated by some simple numerical calculations, and an example is given of a conjugated system (decacyclene) whose molecular graph is apparently non-Hamiltonian. It is emphasized that although much graph theory is inherent in the ring current concept, the ring current index itself is not a completely topological quantity–even when a purely topological wavefunction (such as the simple Hückel one) has been used to calculate it.

Ring current model of the naphthalene molecule

1997 ◽  
Vol 92 (3) ◽  
pp. 609-617 ◽  
Author(s):  
RICCARDO ZANASI ◽  
PAOLO LAZZERETTI
Keyword(s):  
Ring Current ◽  
Current Model ◽  
Naphthalene Molecule

A Methodology of integrated assessment of the investment attractiveness of the priority social and economic development areas

2020 ◽  
Vol 18 (4) ◽  
pp. 780-806 ◽  
Author(s):  
V.A. Yakimova ◽  
S.V. Khmura
Keyword(s):  
Integrated Assessment ◽  
Investment Risk ◽  
Methodological Issues ◽  
Investment Environment ◽  
Social And Economic Development ◽  
Analysis And Synthesis ◽  
Current Assessment ◽  
Development Area ◽  
Internal And External Factors ◽  
Advanced Development

Subject. This article deals with the theoretical and methodological issues of assessing the investment attractiveness of the advanced development areas. Objectives. The article aims to clarify the economic essence of the category Investment Attractiveness of Advanced Development Areas and related categories, and improve the methodological support to assess the investment attractiveness taking into account the characteristics of these areas. Methods. For the study, we used the methods of analysis and synthesis, generalization, analogy, classification, grouping, and systematization. Results. The article presents a methodology for assessing the investment attractiveness of the advanced development areas, taking into account indicators classified under three groups, namely investment potential, investment environment, and investment risk. It also offers recommendations to determine the type of investment attractiveness. Conclusions. Investment attractiveness, as a complex characteristic of the advanced development area, gets formed in the context of the influence of internal and external factors that are quantifiable and qualitatively assessed. To meet the needs of investors, a methodology that includes current assessment and forecasts is needed, indicating the areas of possible investment risk.

Enhancing formative feedback in orthopaedic training: Development and implementation of a competency-based assessment framework

2019 ◽  
Author(s):  
Natalie Wagner ◽  
Anita Acai ◽  
Sydney A. McQueen ◽  
Com McCarthy ◽  
Andrew McGuire ◽  
...  
Keyword(s):  
Intraclass Correlation ◽  
Formative Feedback ◽  
Assessment Practices ◽  
Tool Development ◽  
Assessment Framework ◽  
Educational Impact ◽  
Postgraduate Training Program ◽  
Current Assessment ◽  
Competency Based ◽  
Orthopaedic Training

Objective: The purpose of this study was to develop, implement, and evaluate the effectiveness of an assessment framework aimed at improving formative feedback practices in a Canadian orthopaedic postgraduate training program. Methods: Tool development began in 2014 and took place in 4 phases, each building upon the previous and informing the next. The reliability, validity, and educational impact of the tools were assessed on an ongoing basis, and changes were made accordingly. Results: One hundred eighty-two tools were completed and analyzed during the study period. Quantitative results suggested moderate to excellent agreement between raters (intraclass correlation coefficient = 0.54-0.93), and an ability of the tools to discriminate between learners at different stages of training (p’s < 0.05). Qualitative data suggested that the tools improved both the quality and quantity of formative feedback given by assessors and had begun to foster a culture change around assessment in the program. Conclusions: The tool development, implementation, and evaluation processes detailed in this article can serve as a model for other training programs to consider as they move towards adopting competency-based approaches and refining current assessment practices.

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