scholarly journals Statistical Theory of Unimolecular Reactions and Intramolecular Dynamics

1983 ◽  
Vol 2 (5-6) ◽  
pp. 203-217 ◽  
Author(s):  
R. A. Marcus
Keyword(s):  
Statistical Theory ◽  
Intramolecular Dynamics ◽  
Unimolecular Reactions ◽  
The Past ◽  
Theoretical Developments

In the present lecture we review experimental and theoretical developments in the field of intramolecular dynamics during the past sixty years. In a concluding section we consider possible implications for intramolecular laser selective chemistry.

Kinematics of Meshing Surfaces Using Geometric Algebra

2003 ◽  
Author(s):  
Scott M. Miller
Keyword(s):  
Geometric Algebra ◽  
Screw Theory ◽  
Three Dimensional ◽  
Normal Vector ◽  
The Past ◽  
Geometric Concepts ◽  
Vector Algebra ◽  
The Common ◽  
Two Bodies ◽  
Theoretical Developments

As is well known, analysis of two surfaces in mesh plays a fundamental role in gear theory. In the past, special coordinate systems, vector algebra, or screw theory was used to analyze the kinematics of meshing. The approach here instead relies on geometric algebra, an extension of conventional vector algebra. The elegance of geometric algebra for theoretical developments is demonstrated by examining the so-called “equation of meshing,” which requires that the relative velocity of two bodies at a point of contact be perpendicular to the common surface normal vector. With surprisingly little effort, several alternative forms of the equation of meshing are generated and, subsequently, interpreted geometrically. Via straightforward algebraic manipulations, the results of screw theory and vector algebra are unified. Due to the simplicity with which complex geometric concepts are expressed and manipulated, the effort required to grasp the general three-dimensional meshing of surfaces is minimized.

scholarly journals Magnetic Massive Stars

2007 ◽  
Vol 3 (S250) ◽  
pp. 577-586 ◽  
Author(s):  
Rich Townsend ◽  
David H. Cohen ◽  
Luc Dessart ◽  
Swetlana Hubrig ◽  
Yaël Nazé ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Significant Influence ◽  
Massive Star ◽  
Massive Stars ◽  
Structure Evolution ◽  
Special Session ◽  
The Past ◽  
Recent Developments ◽  
Circumstellar Environments ◽  
Theoretical Developments

AbstractMagnetic fields are unexpected in massive stars, due to the absence of a sub-surface convective dynamo. However, advances in instrumentation over the past three decades have led to their detection in a small but growing subset of these stars. Moreover, complementary theoretical developments have highlighted their potentially significant influence over the structure, evolution and circumstellar environments of massive stars. Here, we summarize a special session convened prior to the main conference, focused on presenting recent developments in the study of massive-star magnetic fields.

The role of quantum intramolecular dynamics in unimolecular reactions

1990 ◽  
Vol 332 (1625) ◽  
pp. 203-220 ◽  
Keyword(s):  
Equations Of Motion ◽  
Classical Mechanics ◽  
Spin Symmetry ◽  
Zero Point ◽  
Fermi Resonance ◽  
Intramolecular Dynamics ◽  
Coupled Modes ◽  
Potential Surfaces ◽  
Unimolecular Reactions ◽  
Point Energy

The dynamics of unimolecular reactions can be modelled by classical mechanics for the motion of nuclei on Born-Oppenheimer or other effective potential surfaces, by the corresponding quantum mechanical equations of motion and, perhaps, by quantum statistical treatments. In this paper I provide a synopsis of fundamental, qualitatively important effects arising from the quantum nature of intramolecular dynamics, as opposed to classical mechanics, and illustrate these with theoretical predictions and experimental examples from the work of my group in Zurich. These include quantum nonlinearity in infrared (IR) multiphoton excitation and reaction, non-classical wavepacket spreading in the Fermi resonance coupled modes in CHX3 molecules, effects of zero point energy and angular momentum in unimolecular reactions, nuclear spin symmetry conservation and inter con version and the hypothetical effects arising from the violation of parity and time reversal symmetry in unimolecular reactions. Specific applications to experiments include IR laser chemistry of CF3I and CF3Br, IR spectroscopy and dynamics of CHF3 and predissociation spectra and dynamics of II

PERCOLATION AND TUNNELING IN COMPOSITE MATERIALS

2004 ◽  
Vol 18 (15) ◽  
pp. 2091-2121 ◽  
Author(s):  
I. BALBERG ◽  
D. AZULAY ◽  
D. TOKER ◽  
O. MILLO
Keyword(s):  
Electrical Transport ◽  
Disordered Systems ◽  
Microcrystalline Silicon ◽  
Physical Processes ◽  
Electrical Transport Properties ◽  
Metal Insulator ◽  
The Past ◽  
Bona Fide ◽  
The Difference ◽  
Theoretical Developments

Classical percolation theory is concerned with the onset of geometrical connectivity and the accompanied onset of electrical connectivity in disordered systems. It was found, however, that in many systems, such as various composites, the geometrical and electrical onsets of the connectivity are not simultaneous and the correlation between them depends on physical processes such as tunneling. The difference between the above two types of systems and the consequences for the electrical transport properties of the latter composites have been largely ignored in the past. The application of scanning local probe microscopies and some recent theoretical developments have enabled a better understanding of the latter systems and their sometimes "strange" behavior as bona fide percolation systems. In this review we consider the above issues and their manifestation in three types of systems: Carbon Black–Polymer composites, metal–insulator cermets and hydrogenated microcrystalline silicon.

scholarly journals PENTAQUARKS

2004 ◽  
Vol 19 (21) ◽  
pp. 3439-3469 ◽  
Author(s):  
SHI-LIN ZHU
Keyword(s):  
Exotic State ◽  
Hadron Physics ◽  
The Past ◽  
Statistical Experiments ◽  
Low Mass ◽  
Exotic Baryon ◽  
Theoretical Developments

Since LEPS collaboration reported the first evidence of Θ+ pentaquark in early 2003, eleven other experimental groups have confirmed this exotic state while many other groups did not see any signal. If this state is further established by future high statistical experiments, its discovery shall be one of the most important events in hadron physics for the past three decades. This exotic baryon with such a low mass and so narrow a width imposes a big challenge to hadron theorists. Up to now, there have appeared more than two hundred theoretical papers trying to interpret this charming state. I will review some important theoretical developments on pentaquarks based on my biased personal views.

Globalization, Transnationalism, and “Mobile Societies” from a Sociological Perspective: Comments on Engseng Ho's “Inter-Asian Concepts for Mobile Societies”

2017 ◽  
Vol 76 (4) ◽  
pp. 935-941
Author(s):  
Jaeeun Kim
Keyword(s):  
Sociological Perspective ◽  
Area Studies ◽  
The Past ◽  
Theoretical Developments ◽  
Do So ◽  
Broad Overview

Speaking across disciplines is always easier said than done. Engseng Ho's thought-provoking article strives to do just that (and achieves the goal nicely), with its broad overview of the literature, the numerous examples that it draws on, and the ambitious conceptual innovations it proposes. As the only sociologist invited to comment on Ho's article, I see my task as bringing Ho's article into fruitful conversation with my own discipline, which is known to be indifferent (if not hostile) to area studies and which (unfortunately) remains largely missing in Ho's imagined audience. I do so by drawing on my own work and some of the theoretical developments in the broader discipline in the past two decades or so. To make intelligible where my comments are coming from, let me begin by briefly introducing what sorts of questions interest me as a sociologist.

scholarly journals Inspiration from the Development of Public Administration in the West for Studies of Public Administration in China

2019 ◽  
Vol 19 (1) ◽  
pp. 23-51
Author(s):  
Lisheng Dong
Keyword(s):  
Public Administration ◽  
The West ◽  
Teaching And Research ◽  
The Past ◽  
Government Role ◽  
Research Programmes ◽  
Chinese Scholars ◽  
Chinese Public ◽  
Theoretical Developments

Many Western-based theories of public administration have had some traction in the Chinese setting. However, they also point to the importance of context and the need to ensure that the theory is relevant to the setting. In this regard, theory needs to be both clearly developed and there are various routes that can be taken. In this article, I share with readers some of my thoughts emanating from my teaching and research over the past two decades, namely, inspiration from the development of public administration in the West for studies of public administration in China. The two analytical lenses that I use for this article are the five essential attributes of public administration and the instrumental and value rationalities as the fundamental nature of the various schools of thought in the development of public administration in the West. The five essential attributes refer to core value, assumptions about human nature, methodology, government role, and disciplinary positioning. They serve as references for my review of the field of public administration in China. Over the last four decades, public administration research in China has resulted in the restoration of the discipline, the flourishing of teaching and research programmes, and active exchanges with colleagues around the world. However, Chinese public administration is facing an “identity crisis”. Chinese scholars have become used to playing the role of consumers of imported concepts, theories, and methods. At this stage it is urgent that they develop their own unique paradigm, including concepts, theories, and methodologies, and contribute to the progress of the whole discipline. The goal of forming their own theoretical framework is urging our Chinese colleagues to challenge themselves to consciously engage in independent theoretical thought. More specifically, they should try to keep abreast of the theoretical developments in the West and lay emphasis on cutting-edge research, avoid not seeing the forest for the trees, and practise timely adoption of dominant theories.

Permutation Tests in the Educational and Behavioral Sciences

Methodology ◽  
2014 ◽  
Vol 10 (2) ◽  
pp. 43-59 ◽  
Author(s):  
Ming Huo ◽  
Mieke Heyvaert ◽  
Wim Van den Noortgate ◽  
Patrick Onghena
Keyword(s):  
Multivariate Analysis ◽  
Permutation Tests ◽  
Group Comparison ◽  
Behavioral Sciences ◽  
Intelligent Algorithms ◽  
The Past ◽  
Brain And Behavior ◽  
And Behavior ◽  
The Relationship ◽  
Theoretical Developments

Over the past two decades, permutation tests (PTs) have received much attention in the educational and behavioral sciences. The aim of this article is to review the theoretical developments of PTs, the active areas in the educational and behavioral research using PTs, and the types of analysis under which PTs have been applied. We obtained 224 published articles, which included 141 theoretical articles and 83 application articles. After scrutinizing each article, we are happy to see that (1) some researchers began to advocate introducing PTs into basic statistics training; (2) computing load for PTs may be reduced dramatically by some intelligent algorithms; (3) PTs began to be applied in new areas such as studies on the relationship between brain and behavior and the relationship between gene and behavior; (4) besides simple types of analysis such as independent two-group comparison, PTs can also be carried out under more complex situations such as multivariate analysis. However, we should also notice that PTs are still mostly used for simple analyses (e.g., randomness analysis).

scholarly journals UNSPEAKABLES AND THE EPISTEMOLOGICAL PATH TOWARD QUANTUM GRAVITY

2008 ◽  
Vol 17 (03n04) ◽  
pp. 425-443 ◽  
Author(s):  
DANIEL SUDARSKY
Keyword(s):  
Quantum Gravity ◽  
Critical Assessment ◽  
The Past ◽  
Guiding Principles ◽  
Theoretical Developments

We offer a critical assessment of some generic features of various current approaches to the construction of a theory of quantum gravity. We argue that there is a need for further conceptual clarifications before such an enterprise can be launched in a truly well-grounded setting, and that one of the guiding principles that can be viewed as part of the reasons for successes of the past theoretical developments is the identification of unspeakables — concepts that should not only play no role in the formulation of the theories, but ones that the formalism of the theory itself should prevent from ever being spoken about.

Trust in Social Dilemmas

2017 ◽  
Keyword(s):  
Intergroup Relations ◽  
State Of The Art ◽  
Social Dilemmas ◽  
Future Research ◽  
Contemporary Society ◽  
Societal Issues ◽  
The Past ◽  
The Social ◽  
Emerging Themes ◽  
Theoretical Developments

Trust is one of the most classic themes across the social and behavioral sciences. It is also a topic is that is strongly intertwined with cooperation and social dilemmas, and there is little doubt that trust is an effective tool to promote cooperation, even if cooperation without trust is possible under certain circumstances. The past decade has also increasingly revealed emerging themes, new theoretical developments, intriguing questions, and a challenging debate revolving around the evolution, as well as strengths and limitations, of trust in social dilemmas and other situations of interdependence. Major societal issues are partially issues of trust: the financial crisis and the refuge crisis are two examples. Why can systems of excessive bonuses emerge and survive? Why is it that we tend to approach individuals with a healthy dose of trust, but we tend to be suspicious of other groups—or even individual members of other groups? Some scientists make the claim that it is ultimately trust—or rather the lack of it—that undermines intergroup relations. One of the next challenges is to examine the workings of trust and how best to organize a system that exploits the opportunities of trust within groups and between groups in contemporary society. We hope this book provides a state of the art of this literature and that the themes discussed in this book will indeed turn out to be prominent ones in future research on trust in social dilemmas—whether they operate at the level of interpersonal or intergroup relations.

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