Generic Nekhoroshev theory without small divisors

In this article, we present a new approach of Nekhoroshev theory for a generic unperturbed Hamiltonian which completely avoids small divisors problems. The proof is an extension of a method introduced by P. Lochak which combines averaging along periodic orbits with simultaneous Diophantine approximation and uses geometric arguments designed by the second author to handle generic integrable Hamiltonians. This method allows to deal with generic non-analytic Hamiltonians and to obtain new results of generic stability around linearly stable tori

Rigorous treatment of the averaging process for co-orbital motions in the planetary problem

We develop a rigorous analytical Hamiltonian formalism adapted to the study of the motion of two planets in co-orbital resonance. By constructing a complex domain of holomorphy for the planetary Hamilto-nian, we estimate the size of the transformation that maps this Hamil-tonian to its first order averaged over one of the fast angles. After having derived an integrable approximation of the averaged problem, we bound the distance between this integrable approximation and the averaged Hamiltonian. This finally allows to prove rigorous theorems on the behavior of co-orbital motions over a finite but large timescale

Modeling of oligomeric-state dependent spectral heterogeneity in the B875 light-harvesting complex of Rhodobacter sphaeroides by numerical simulation

A series of detergent-isolated light-harvesting 1 (LH1, B875) complexes from Rhodobacter sphaeroides, estimated to range in size from (RâBChl2)4 to (RâBChl2)13, was used to study the combined effects of spectral disorder and excitonic interactions on oligomeric-state dependent optical properties. Numerical simulations of absorption and fluorescence emission, excitation, and polarization spectra, based on the structure of the related LH2 complex, were compared to spectra measured experimentally at 77 K (Westerhuis and Niederman, in preparation). The aggregation-state dependence of the polarization spectra was found to be particularly sensitive to the choice of parameters, and vibronic components were included to obtain satisfactory simulations. Good agreement with most experimental features, including the oligomeric-state dependence of the absorption and emission maxima, was obtained only when the inter- and intradimer coupling strengths for adjacent BChls were similar (200-260 cm-1), and the width for the inhomogeneous distribution function (300-400 cm-1) was comparable. The relevance of these findings to existing controversies on the physical origin of spectral heterogeneity observed for the LH1 complex is discussed

Using Grounded Theory to Generate Indigenous MIS Theory

Much of the research in the Information Systems (IS) field has been dominated by the application of reference discipline theory to IS phenomena. While this has provided useful lenses for rapid development of a theory base for IS, it has also helped shape the IS domain as an amalgam of heterogeneous topics, methods, and lessons, many of which apply more to behavioral science in general than IS in particular. This workshop aims to aid interested researchers in techniques for the direct examination of IS phenomena and procedures for the development of indigenous theory. Grounded theory is a well known and well used methodology applied broadly across many areas of study and is highly appropriate for theory development. This workshop will touch lightly on general principles and underlying theory of this method and provide direct hands-on activities aimed at skill building for the use of grounded theory in research projects, with significant prospects for high quality publication. This workshop is co-sponsored by the AIS special interest group on grounded theory

But Is It MIS?

From the perspective of a doctoral student, there are several inferences to be made from the Is it MIS? question. First are inferences pertaining to the nature of MIS as a system (or set of systems) focusing on issues including purpose and boundary. Second are inferences about the role and responsibilities of the individual researcher relative to the MIS community. Third are inferences about science and the nature of inquiry. This dimension considered, even if it is MIS, does it support MIS as a worthy component of a larger world of inquiry. This article addresses these issues and concludes with some thoughts about Gary Dickson\u27s contribution through this and similar questions on the MIS field

Why Future Studies Provides a Critical Opportunity for the IS Discipline

This paper argues that the Futures Studies research approach is of interest and importance to the IS discipline and community. It elaborates on aspects of empirical IS that need reconceptualization to accommodate the unique aspects of studying the future and how these might be incorporated into the MIS canon

Reflections on CAIS and the IS Field from a Former Editor-in-Chief

This essay represents the lessons I learned over a three-year term serving as editor-in-chief of Communications of the Association for Information Systems (CAIS). The discussion revolves around general observations of the IS field, the relationship between these observations of the IS field and CAIS and CAIS\u27s unique mission and how that mission serves stakeholders, authors, readers, editorial team members, and touches on the logistics of managing a journal. The discussions focus on the use of theory in IS knowledge production, the meaning of a contribution, the goal of examining and challenging widely held assumptions and positions, as well as building on prior knowledge

Responding to Three Issues in Hassan (2014)

This article is intended to address three of the issues raised by Hassan (2014) in his essay: “Value of Information Systems (IS) Research: Is there a Crisis?”. The three issues addressed here pertain to: (1) the desirability and nature of an IS core; (2) the relative social value in the study of IS whether narrowly or broadly defined; and (3) indicators of better research. Regarding the core, an argument for a narrow definition of the core is proposed with the view of providing a target for retention of central issues in IS rather than as a defining characteristic of what is necessary for inclusion in the IS portfolio. The meaning of social value will naturally and beneficially vary among the large number of IS scholars. It is of importance to recognize and stimulate, without mandating, efforts to bridge traditional IS concerns and broader social issues. The various criteria for evaluating value in IS, or any other research domain, are challenged with counter examples. Finally, suggestions for moving forward are presented