Search results for "bundle"
showing 10 items of 257 documents
Vector supersymmetry in the universal bundle
1991
Abstract We present a vector supersymmetry for Witten-type topological gauge theories, and examine its algebra in terms of a superconnection formalism. When covariant constraints on the supercurvature are chosen, a correspondence is established with the universal bundle construction of Atiyah and Singer. The vector supersymmetry represents a certain shift operator in the curvature of the universal bundle, and can be used to generate the hierarchy of observables in these theories. This formalism should lead to the construction of vector supergravity theories, and perhaps to the gravitational analogue of the universal bundle.
Presymplectic manifolds and conservation laws
2008
In this paper we make use of a new structure called seeded fibre bundle. This allows us to combine the symplectic formalism and general relativity. A theorem of existence is obtained and some examples and properties are studied.
Branch-and-Bound
2010
We now turn to the discussion of how to solve the linear ordering problem to (proven) optimality. In this chapter we start with the branch-and-bound method which is a general procedure for solving combinatorial optimization problems. In the subsequent chapters this approach will be realized in a special way leading to the so-called branch-and-cut method. There are further possibilities for solving the LOP exactly, e.g. by formulating it as dynamic program or as quadratic assignment problem, but these approaches did not lead to the implementation of practical algorithms and we will not elaborate on them here.
Five-year experience with combined operative and radiotherapeutic treatment of recurrent gynecologic tumors infiltrating the pelvic wall
1996
BACKGROUND. Whereas 25 to 50% of selected patients with gynecologic tumors who relapse centrally in an irradiated pelvis can be salvaged by exenteration, postirradiation recurrence infiltrating the pelvic side wall generally has been fatal. We have designed the combined operative and radiotherapeutic treatment (CORT) procedure for the treatment of postirradiation recurrence infiltrating the pelvic wall and developed several new techniques for its realization. The aim of the surgery is as follows : (1) total resection of the tumor with only a microscopic margin (R1) at the pelvic wall, preserving the bony pelvis and the neurovascular support of the leg ; (2) modulation of the therapeutic ind…
The impact of service bundles on the mechanism through which functional value and price value affect WOM intent
2017
Purpose The purpose of this paper is to contribute toward the current limited understanding of service bundles by investigating how purchasers of combined product-service bundles (bundle customers) differ from those purchasing a product and associated service separately (non-bundle customers). Design/methodology/approach The hypothesized effects were tested on a representative sample of mobile phone subscribers in Finland, through a multi-group moderated analysis using variance-based structural equation modeling. Findings While functional value had a stronger effect on attitude for bundle customers, price value is a stronger determinant of attitude for non-bundle customers. There was no di…
The Surgery of Neglected Distal Humerus Fractures in Children and Adults
2008
The restoration of function after a neglected distal humerus fracture presents a formidable challenge to the surgeon because of both the complexity of the regional anatomy and the proximity of numerous neurovascular structures. Inadequate or unstable fixation, a failure to reposition the articular fragments anatomically, prolonged post-operative immobilization, or the development of soft-tissue complications will result in substantial disability for the patient. Complications after injuries affecting a child’s elbow are common due to understimating the severity of the injury on the native X-rays where the growth plates and cartilage structures can not be seen.
A curved Lowsley retractor improves manoeuvrability of the prostate during ascending radical retropubic prostatectomy
2007
Worldwide, radical retropubic prostatectomy is the commonest surgical procedure for treating localized prostate cancer. The technique has evolved continuously over the years, yielding improved continence and potency while reducing considerably the associated complications. Simple surgical ‘tricks’ have been proposed for crucial steps, e.g. the control of the dorsal venous complex, atraumatic dissection of the neurovascular bundles (NVBs), improved visualization of the urethral stump and tailoring of the vesicourethral anastomosis [1,2].
Kähler Tubes of Constant Radial Holomorphic Sectional Curvature
1997
We determine (up to holomorphic isometries) the family of Kahler tubes, around totally geodesic complex submanifolds, of constant radial holomorphic sectional curvature when the centreP of the tube is either simply connected or a complex hypersurface withH1 (P, R)=0. In the last case, these tubes have the topology of tubular neighbourhoods of the zero section of the complex lines bundles over symplectic manifolds (when they are Kahler) of the Kostant-Souriau prequantization.
On the stability of flat complex vector bundles over parallelizable manifolds
2017
We investigate the flat holomorphic vector bundles over compact complex parallelizable manifolds $G / \Gamma$, where $G$ is a complex connected Lie group and $\Gamma$ is a cocompact lattice in it. The main result proved here is a structure theorem for flat holomorphic vector bundles $E_\rho$ associated to any irreducible representation $\rho : \Gamma \rightarrow \text{GL}(r,{\mathbb C})$. More precisely, we prove that $E_{\rho}$ is holomorphically isomorphic to a vector bundle of the form $E^{\oplus n}$, where $E$ is a stable vector bundle. All the rational Chern classes of $E$ vanish, in particular, its degree is zero. We deduce a stability result for flat holomorphic vector bundles $E_{\r…
An Introduction to Hodge Structures
2015
We begin by introducing the concept of a Hodge structure and give some of its basic properties, including the Hodge and Lefschetz decompositions. We then define the period map, which relates families of Kahler manifolds to the families of Hodge structures defined on their cohomology, and discuss its properties. This will lead us to the more general definition of a variation of Hodge structure and the Gauss-Manin connection. We then review the basics about mixed Hodge structures with a view towards degenerations of Hodge structures; including the canonical extension of a vector bundle with connection, Schmid’s limiting mixed Hodge structure and Steenbrink’s work in the geometric setting. Fin…