scholarly journals AN APPROXIMATE MODEL OF THE SPACETIME FOAM

2002 ◽  
Vol 11 (03) ◽  
pp. 299-310
Author(s):  
V. DZHUNUSHALIEV
Keyword(s):  
Electromagnetic Fields ◽  
Spinor Field ◽  
Approximate Model ◽  
Effective Model ◽  
Field Equations ◽  
Wormhole Throat ◽  
First Case ◽  
Definition Of ◽  
Spacetime Foam ◽  
Effective Description

An approximate model of the spacetime foam is offered in which a quantum handle (wormhole) is a 5D wormhole-like solution. Neglecting the linear sizes of the wormhole throat we can introduce a spinor field for an approximate and effective description of the foam. The definition of the spinor field can be made by a dynamic and nondynamic ways. In the first case some field equations are used and the second case leads to superspace. It is shown that the spacetime with the foam is similar to a dielectric with dipoles and supergravity theories with a nonminimal interaction between spinor and electromagnetic fields can be considered as an effective model for the spacetime foam.

GEOMETRIZATION OF ELECTROMAGNETISM IN TETRAD-SPIN-CONNECTION GRAVITY

2009 ◽  
Vol 24 (06) ◽  
pp. 431-442 ◽  
Author(s):  
NIKODEM J. POPŁAWSKI
Keyword(s):  
Variational Principle ◽  
Electromagnetic Fields ◽  
Spinor Field ◽  
Maxwell Equations ◽  
Electromagnetic Coupling ◽  
Ricci Scalar ◽  
Spin Connection ◽  
Electromagnetic Potential ◽  
Field Equations ◽  
Generally Covariant

The metric-affine Lagrangian of Ponomarev and Obukhov for the unified gravitational and electromagnetic fields is linear in the Ricci scalar and quadratic in the tensor of homothetic curvature. We apply to this Lagrangian the variational principle with the tetrad and spin connection as dynamical variables and show that, in this approach, the field equations are the Einstein–Maxwell equations if we relate the electromagnetic potential to the trace of the spin connection. We also show that, as in the Ponomarev–Obukhov formulation, the generally covariant Dirac Lagrangian gives rise to the standard spinor source for the Einstein–Maxwell equations, while the spinor field obeys the nonlinear Heisenberg–Ivanenko equation with the electromagnetic coupling. We generalize that formulation to spinors with arbitrary electric charges.

scholarly journals Killing superalgebras for lorentzian five-manifolds

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Andrew Beckett ◽  
José Figueroa-O’Farrill
Keyword(s):  
Spin Manifold ◽  
Field Equations ◽  
Spinor Bundle ◽  
Killing Spinors ◽  
Spinor Connection ◽  
Spencer Cohomology ◽  
Definition Of ◽  
Supersymmetric Theories ◽  
Filtered Deformations

Abstract We calculate the relevant Spencer cohomology of the minimal Poincaré superalgebra in 5 spacetime dimensions and use it to define Killing spinors via a connection on the spinor bundle of a 5-dimensional lorentzian spin manifold. We give a definition of bosonic backgrounds in terms of this data. By imposing constraints on the curvature of the spinor connection, we recover the field equations of minimal (ungauged) 5-dimensional supergravity, but also find a set of field equations for an $$ \mathfrak{sp} $$ sp (1)-valued one-form which we interpret as the bosonic data of a class of rigid supersymmetric theories on curved backgrounds. We define the Killing superalgebra of bosonic backgrounds and show that their existence is implied by the field equations. The maximally supersymmetric backgrounds are characterised and their Killing superalgebras are explicitly described as filtered deformations of the Poincaré superalgebra.

Rash and Mucositis Associated With Mycoplasma pneumoniae and Chlamydophila pneumoniae: A Recurrence of MIRM?

2020 ◽  
Author(s):  
Danielle Brazel ◽  
Brooke Kulp ◽  
Geoanna Bautista ◽  
Andrew Bonwit
Keyword(s):  
Mycoplasma Pneumoniae ◽  
Treatment Options ◽  
Specific Treatment ◽  
Corticosteroid Treatment ◽  
Stevens Johnson Syndrome ◽  
First Case ◽  
Johnson Syndrome ◽  
Vesicular Rash ◽  
Recurrent Aphthous Ulcers ◽  
Definition Of

Abstract Introduction A new concept has come to light recently, that is, Mycoplasma-induced rash and mucositis (MIRM). Here, we report the first case of recurrent rash, mucositis, and conjunctivitis involving Mycoplasma pneumoniae and C. pneumoniae that fits under the criteria of what is currently defined as MIRM. Case Presentation A patient aged 12 years with a history of recurrent aphthous ulcers presented in 2013 with worsening oral lesions, conjunctivitis, and vesicular rash. Her respiratory polymerase chain reaction (PCR) panel was positive for M. pneumoniae. She was diagnosed with Stevens-Johnson syndrome (SJS) secondary to M. pneumoniae and treated with a macrolide, acyclovir, and intravenous immunoglobulin (IVIG). The same patient returned 3 years later with an identical constellation of symptoms, at which time her PCR was positive for C. pneumoniae. In addition to IVIG and a macrolide, a corticosteroid treatment was administered. Discussion Here, we present the case of a pediatric patient with a recurrence of mucocutaneous disease that is more consistent with MIRM than the proposed SJS or erythema multiforme (EM) documented via histology. Our patient’s symptoms were controlled with azithromycin and IVIG and, in the second episode, with corticosteroids as well. This case adds to that of Mayor-Ibarguren et al, providing further evidence that C. pneumonia may also be a trigger for MIRM. Patients will benefit from expanding the definition of MIRM, as the pathogenesis differs from SJS and EM and could result in more specific treatment options.

On Conformally Covariant Spinor Field Equations

1972 ◽  
Vol 50 (18) ◽  
pp. 2100-2104 ◽  
Author(s):  
Mark S. Drew
Keyword(s):  
Minkowski Space ◽  
Invariant Mass ◽  
Spinor Field ◽  
Dimensional Space ◽  
Flat Space ◽  
Field Equations ◽  
First Order ◽  
Conformally Invariant ◽  
Spinor Fields

Conformally covariant equations for free spinor fields are determined uniquely by carrying out a descent to Minkowski space from the most general first-order rotationally covariant spinor equations in a six-dimensional flat space. It is found that the introduction of the concept of the "conformally invariant mass" is not possible for spinor fields even if the fields are defined not only on the null hyperquadric but over the entire manifold of coordinates in six-dimensional space.

scholarly journals Dynamics of scalar potentials in theory of gravity

2019 ◽  
Vol 97 (8) ◽  
pp. 880-894
Author(s):  
M. Zubair ◽  
Farzana Kousar ◽  
Saira Waheed
Keyword(s):  
Scalar Field ◽  
Field Potential ◽  
Graphical Analysis ◽  
Chaplygin Gas ◽  
Field Potentials ◽  
De Sitter ◽  
Field Equations ◽  
Barotropic Fluid ◽  
First Case ◽  
De Sitter Universe

In this paper, we explore the nature of scalar field potential in [Formula: see text] gravity using a well-motivated reconstruction scheme for flat Friedmann–Robertson–Walker (FRW) geometry. The beauty of this scheme lies in the assumption that the Hubble parameter can be expressed in terms of scalar field and vice versa. Firstly, we develop field equations in this gravity and present some general explicit forms of scalar field potential via this technique. In the first case, we take the de Sitter universe model and construct some field potentials by taking different cases for the coupling function. In the second case, we derive some field potentials using the power law model in the presence of different matter sources like barotropic fluid, cosmological constant, and Chaplygin gas for some coupling functions. From graphical analysis, it is concluded that using some specific values of the involved parameters, the reconstructed scalar field potentials are cosmologically viable in both cases.

scholarly journals Anaplastic pilocytic astrocytoma of the cerebellum presenting with conus medullaris drop metastasis

2021 ◽  
Vol 8 (1) ◽  
pp. 10
Author(s):  
Jared F. Sweeney ◽  
Vaibhav Chumbalkar ◽  
Michael D. Staudt ◽  
Pouya Entezami ◽  
Jiang Qian ◽  
...  
Keyword(s):  
Pilocytic Astrocytoma ◽  
Cauda Equina ◽  
Conus Medullaris ◽  
Complete Understanding ◽  
First Case ◽  
Spine Imaging ◽  
Drop Metastasis ◽  
Cerebellar Mass ◽  
Definition Of ◽  
Staged Operations

Due to its rarity, a complete understanding of the clinical behavior, pathogenesis, and diagnostic definition of anaplastic pilocytic astrocytoma (APA) is currently lacking. The optimal clinical management and use of adjuvant therapies has yet to be defined. We present a 64 year-old-female with progressive headaches, dysarthria, and ataxia, who was found to have right cerebellar mass. A gross total resection was achieved through two staged operations. Pathology demonstrated focal areas of necrosis, tumor infiltration, and increased mitotic activity most consistent with APA. Adjuvant chemotherapy and stereotactic radiosurgery were administered. Approximately two years later, the patient presented with symptoms of cauda equina syndrome, and lumbar spine imaging demonstrated a large intradural mass at the conus medullaris with diffuse leptomeningeal enhancement. A biopsy was performed and was consistent with metastatic APA. APA may rarely progress to metastatic disease, most frequently involving the leptomeninges of the posterior fossa and cervical spine. This report represents the first case of metastases distal to the cervicomedullary junction.

Algorithm-Based Support for the Redesign of Product Variants

2020 ◽  
Author(s):  
Julian Redeker ◽  
Philipp Gebhardt ◽  
Thomas Vietor
Keyword(s):  
Economies Of Scale ◽  
Graph Matching ◽  
Product Family ◽  
Automated Analysis ◽  
Production Volume ◽  
Scale Production ◽  
Product Families ◽  
First Case ◽  
Subtractive Manufacturing ◽  
Definition Of

Abstract Incremental Manufacturing is a novel manufacturing approach where product variants are manufactured based on a finalization of pre-produced parts through additive and subtractive manufacturing processes. This approach allows a multi-scale production with the possibility to scale product variants as well as the production volume. In order to ensure high economic efficiency of the manufacturing concept, there is a need for pre-produced parts that come as close as possible to the final variant geometries to ensure that only variant-specific features need to be added by additive or subtractive manufacturing steps. Furthermore, to ensure high economies of scale, a high degree of commonality should be ensured for the pre-produced parts manufactured in mass production. In this context, a graph-based method is developed that enables an automated analysis of product families, based on physical and functional attributes, for standardization potentials. The method thus provides support for the strategic definition of pre-produced parts and is embedded in an overall approach for the redesign of products for Incremental Manufacturing. For the demonstration of the approach, which is based on 3D Shape and Graph Matching methods, a first case study is carried out using a guiding bush product family as an example.

Explanatory Model of Adoption, Development and Utilization of Administrative Workflow Systems

2015 ◽  
Vol 7 (4) ◽  
pp. 31-52
Author(s):  
Mário Dias Lousã ◽  
José Augusto Monteiro
Keyword(s):  
Literature Review ◽  
Case Studies ◽  
Explanatory Model ◽  
Organizational Changes ◽  
Workflow Systems ◽  
Workflow System ◽  
First Case ◽  
Development And Utilization ◽  
Definition Of ◽  
Internal And External Factors

With this article the authors intend to present an explanatory model about the process of adoption, development and deployment of workflow systems and the resulting organizational changes. Throughout the article they highlight major internal and external factors that influence the organization, adoption and development of the workflow system. The model, the factors and organizational changes introduced in this article emerged from the literature review and two case studies. The results of the literature review led to the definition of the concepts and subjects that were developed in the case studies. The first case consisted of a longitudinal study where the authors followed the process of adoption and development of a workflow system in a company. The second case study consisted of a post-implementation workflow system - retrospective study.

Unified Field Theory

1950 ◽  
Vol 2 ◽  
pp. 427-439 ◽  
Author(s):  
Max Wyman
Keyword(s):  
Field Theory ◽  
Variational Principle ◽  
Electromagnetic Fields ◽  
Linear Connection ◽  
Hamiltonian Function ◽  
Unified Theory ◽  
Unified Field Theory ◽  
Field Equations ◽  
Unified Field

Introduction. In a recent unified theory originated by Einstein and Straus [l], the gravitational and electromagnetic fields are represented by a single nonsymmetric tensor gy which is a function of four coordinates xr(r = 1, 2, 3, 4). In addition a non-symmetric linear connection Γjki is assumed for the space and a Hamiltonian function is defined in terms of gij and Γjki. By means of a variational principle in which the gij and Γjki are allowed to vary independently the field equations are obtained and can be written(0.1)(0.2)(0.3)(0.4)

E pluribus unum? Language diversity and the harmonization of company law in the European Union

2019 ◽  
Vol 26 (5) ◽  
pp. 669-690
Author(s):  
Federico M Mucciarelli
Keyword(s):  
European Union ◽  
Case Studies ◽  
Company Law ◽  
Language Diversity ◽  
The European Union ◽  
Freedom Of Establishment ◽  
First Case ◽  
Definition Of ◽  
The Impact

This work addresses the impact of language diversity and nation-specific doctrinal structures on harmonized company law in the EU. With this aim, two emblematic case studies will be analysed. The first case study is related to the definition of ‘merger’ adopted in the Company Law Directive 2017/1132 (originally in the Third Company Law Directive and the Cross-Border Merger Directive); by relying on the example of the SEVIC case decided by the Court of Justice of the European Union (CJEU), it will be shown that scholars’ and courts’ conception of the definition of ‘merger’ varies according to own domestic doctrinal structures. The second case study is related to the notion of ‘registered office’, which is key for establishing the scope of several harmonizing provisions and the freedom of establishment; this paper analyses terminological fluctuations across language versions of EU legislation and the impact of domestic taxonomies and legal debates upon the interpretation of these notions. These case studies show that company law concepts, despite their highly technical nature, are influenced by discourse constructions conducted within national interpretative communities, and by the language used to draft statutory instruments and discuss legal issues. The task of the CJEU is to counterbalance these local tendencies, and yet it is unlikely that doctrinal structures, rooted in national languages and legal cultures, will disappear.

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