193,215 research outputs found
Gordon, Gary D., October 31, 2010 [Interview]
No full textGary D. Gordon was interviewed on October 31, 2010, by Teddy Smith about his experiences during World War II.World War II
Finite size effects and the supersymmetric sine-Gordon models
No full textWe propose nonlinear integral equations to describe the groundstate energy of the fractional supersymmetric sine-Gordon models. The equations encompass the N = 1 supersymmetric sine-Gordon model as well as the phi(id,id,adj) perturbation of the SU(2)(L) x SU(2)(K)/SU(2)(L+K) models at rational level K. A second set of equations is proposed for the groundstate energy of the N = 2 supersymmetric sine-Gordon model
The complex sine-Gordon model on a half line
No full textIn this thesis, we study the complex sine-Gordon model on a half line. The model in the bulk is an integrable (l+1) dimensional field theory which is U(1) gauge invariant and comprises a generalisation of the sine-Gordon theory. It accepts soliton and breather solutions. By introducing suitably selected boundary conditions we may consider the model on a half line. Through such conditions the model can be shown to remain integrable and various aspects of the boundary theory can be examined. The first chapter serves as a brief introduction to some basic concepts of integrability and soliton solutions. As an example of an integrable system with soliton solutions, the sine-Gordon model is presented both in the bulk and on a half line. These results will serve as a useful guide for the model at hand. The introduction finishes with a brief overview of the two methods that will be used on the fourth chapter in order to obtain the quantum spectrum of the boundary complex sine-Gordon model. In the second chapter the model is properly introduced along with a brief literature review. Different realisations of the model and their connexions are discussed. The vacuum of the theory is investigated. Soliton solutions are given and a discussion on the existence of breathers follows. Finally the collapse of breather solutions to single solitons is demonstrated and the chapter concludes with a different approach to the breather problem. In the third chapter, we construct the lowest conserved currents and through them we find suitable boundary conditions that allow for their conservation in the presence of a boundary. The boundary term is added to the Lagrangian and the vacuum is reexamined in the half line case. The reflection process of solitons from the boundary is studied and the time-delay is calculated. Finally we address the existence of boundary-bound states. In the fourth chapter we study the quantum complex sine-Gordon model. We begin with a brief overview of the theory in the bulk where the semi-classical spectrum and an exact S'-matrix are presented. Following that we use the stationary phase method to derive the semi-classical spectrum of boundary bound states. The bootstrap method is used as an alternative approach to obtain the same spectrum. The results are discussed and compared. The final chapter consists of a general discussion on open questions and problems of the model, and some proposals for further research
Cephaloscymnus gnomus Gordon
No full text10. Cephaloscymnus gnomus Gordon Cephaloscymnus gnomus Gordon 1974: 46. Distribution. MEXICO: El Salto de Agua, San Lus Potosi. (CMNC). Remarks. The small size, nearly all black dorsal surface, and coarse dense elytral punctures distinguish C. gnomus from other Cephaloscymnus species. Male unknown.Published as part of Gordon, Robert D. & Hanley, Guy A., 2017, South American Coccinellidae (Coleoptera), Part XVII: systematic revision of Western Hemisphere Cephaloscymnini (Coccinellinae) with description of a cryptic new genus and species of Coccidulini (Coccinellinae), pp. 1-158 in Insecta Mundi 2017 (601) on page 9, DOI: 10.5281/zenodo.517003
Cephaloscymnus insulatus Gordon Pronotum 1970
No full text9. Cephaloscymnus insulatus Gordon Cephaloscymnus insulatus Gordon 1970: 69. Distribution. UNITED STATES: Arizona, Santa Rita Mts. (USNM). Remarks. Most similar in appearance to C. occidentalis, but female genitalia differ strongly. Genitalia illustrations and other illustrations are presented here (Fig. 40–44).Published as part of Gordon, Robert D. & Hanley, Guy A., 2017, South American Coccinellidae (Coleoptera), Part XVII: systematic revision of Western Hemisphere Cephaloscymnini (Coccinellinae) with description of a cryptic new genus and species of Coccidulini (Coccinellinae), pp. 1-158 in Insecta Mundi 2017 (601) on page 9, DOI: 10.5281/zenodo.517003
On the integrability of the sine-Gordon system
No full textThis thesis investigates the integrability of the sine-Gordon system of nonlinear partial differential equations when the dependent variables are subject to some very particular boundary conditions. In chapter 1 the sine-Gordon system is introduced and, with N ϵ Z, P, Q ϵ R, the sets of initial-boundary value problems A(_N) and B(_P,Q) are defined. In the set A(_N) at the spatial variable x is unbounded and the boundary conditions are fixed by initially choosing the topological charge N. This set of problems is the one usually associated with the sine-Gordon system. In the set B(_P,Q) the spatial coordinate is constrained to the semi-line (-oo,0) and there exists two boundary parameters P,Q ϵ R to be chosen a priori. It is the study of this second set of initial-boundary value problems for arbitrary P, Q which forms all the original work of this dissertation. The study presented here is primarily concerned with the development of three separate inverse scattering methods for solving these sets of initial-boundary value problems. The first of these is developed in chapter 3 and is applicable to a subset of the problems in A(_N). The method is the one usually associated with the sine-Gordon system and studies the asymptotics of the initial data as x → ±oo. It is included in this thesis for completeness and as background for the original material which follows. Next, in chapters 4 and 5, the inverse scattering methods appropriate to initial-boundary value problems in subsets of B(_P,O) and B(_P,Q#O) are constructed. In these cases it is important to realise that it is only possible to study the asymptotics of the initial data as x → -oo. Once these three methods have been formulated they are used to find soliton solutions and infinite sets of integrals of motion for these boundary value problems. When a boundary is present at x = 0 the interaction of the solitons with this boundary is studied. These topics are addressed in chapter 6. Finally in chapter 7 the question of the integrability of both sets of problems is addressed. By interpreting the various inverse scattering methods in terms of canonical coordinate transformations of phase space it is seen that the existence of such methods can be viewed as a constructive proof of the integrability of these boundary value problems
Schaefferellus Gordon and Skelley 2007
No full textSchaefferellus Gordon and Skelley, 2007 Schaefferellus arizonensis (Schaeffer, 1907: 61) [Aphodius], Mexico, USA.Published as part of Skelley, Paul E., Dellacasa, Marco, Dellacasa, Giovanni & Gordon, Robert D., 2007, Checklist of the Aphodiini of Mexico, Central and South America (Coleoptera: Scarabaeidae: Aphodiinae), pp. 1-14 in Insecta Mundi 2007 (14) on page 7, DOI: 10.5281/zenodo.453262
Cephaloscymnus mexicanus Gordon & Hanley 2017
No full text3. Cephaloscymnus mexicanus Gordon Cephaloscymnus mexicanus Gordon 1974: 45. Distribution. MEXICO: Coahuila, nr Jame 33 mi. S. El Saltillo; 30 mi. W. Durango, Durango,8000'. Durango, 3 mi. E. El Salto. (CMNC) (USNM). Remarks. Male genitalia are of the C. australis type but the basal lobe is longer, more slender, and not as abruptly curved. Male genitalia illustrations and other illustrations are presented here (Fig. 8–12).Published as part of Gordon, Robert D. & Hanley, Guy A., 2017, South American Coccinellidae (Coleoptera), Part XVII: systematic revision of Western Hemisphere Cephaloscymnini (Coccinellinae) with description of a cryptic new genus and species of Coccidulini (Coccinellinae), pp. 1-158 in Insecta Mundi 2017 (601) on pages 6-7, DOI: 10.5281/zenodo.517003
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