Search results for " category theory"
showing 10 items of 70 documents
Normalities and Commutators
2010
We first compare several algebraic notions of normality, from a categorical viewpoint. Then we introduce an intrinsic description of Higgins' commutator for ideal-determined categories, and we define a new notion of normality in terms of this commutator. Our main result is to extend to any semi-abelian category the following well-known characterization of normal subgroups: a subobject K is normal in A if. and only if, {[A, K] <= K. (C) 2010 Elsevier Inc. All rights reserved.}
The Jyväskylä Accelerator Laboratory
2014
The Jyvaskyla Accelerator Laboratory is a national center for nuclear and accelerator-based research and education. It is an integral part of the Department of Physics, University of Jyvaskyla. The Accelerator Laboratory and the Department Physics were moved to the current site in the early 1990s, as described in the previous Laboratory Portrait published in 1991 [1]. Since then the research program of the laboratory has been structured around the main instruments and research fields, which share the available beam time. The present laboratory layout is shown in Figure 1. In addition to basic research in nuclear and accelerator based materials physics, beam time is reserved for commercial s…
A Four-Year Observational Study regarding the Characteristics and Causes of the Ischemic Stroke in Young Adults: one center study report
2020
Introduction. Stroke is the second cause of mortality worldwide, after the ischemic coronary disease, and the first cause of long term-disability. Recent studies report that ischemic stroke (IS) in young patients is increasing in incidence, even though the overall stroke hospitalization rate is decreasing. Stroke in the young, working individuals significantly affects the quality of life (QoL) and also determines an important, negative economic impact by reducing the workforce. Material and method. The aim of this paper is to present the results of a 4-year observational, retrospective study on all patients between 18-49 years, who suffered from acute IS and were admitted and investigated i…
A two-center-oscillator-basis as an alternative set for heavy ion processes
1977
The two-center-oscillator-basis, which is constructed from harmonic oscillator wave functions developing about two different centers, suffers from numerical problems at small center separations due to the overcompleteness of the set. In order to overcome these problems we admix higher oscillator wave functions before the orthogonalization, or antisymmetrization resp. This yields a numerically stable basis set at each center separation. The results obtained for the potential energy surface are comparable with the results of more elaborate models.
Masses and magnetic moments of ground-state baryons in covariant baryon chiral perturbation theory
2012
We report on some recent developments in our understanding of the light-quark mass dependence and the SU(3) flavor symmetry breaking corrections to the magnetic moments of the ground-state baryons in a covariant formulation of baryon chiral perturbation theory, the so-called EOMS formulation. We show that this covariant ChPT exhibits some promising features compared to its heavy-baryon and infrared counterparts.
Brightness induction in a chromatic center?achromatic surround configuration
1997
Measurements of Thermal and Resonance Neutron Fluence and Induced Radioactivity Inside Bunkers of Medical Linear Accelerators in the Center of Oncolo…
2016
Emission of high-energy X-ray and electron therapeutic beams from medical linear accelerators is related to undesirable neutron production and to induction of radioactivity. In this work, measurements of thermal and resonance neutron fluence and induced radioactivity were performed inside two bunkers with medical linacs — Elekta in the Center of Oncology in Opole (Poland). The bunkers differ with a construction of their walls. The neutron measurements were performed by means of the induced activity method during emission of the 18 MV X-ray beam. The investigation of radioactivity induced by neutrons was based on the method of off-line gammaray spectroscopy measurements. This work has shown …
Models and solution methods for the uncapacitatedr-allocationp-hub equitable center problem
2017
Hub networks are commonly used in telecommunications and logistics to connect origins to destinations in situations where a direct connection between each origin–destination (o-d) pair is impractical or too costly. Hubs serve as switching points to consolidate and route traffic in order to realize economies of scale. The main decisions associated with hub-network problems include (1) determining the number of hubs (p), (2) selecting the p-nodes in the network that will serve as hubs, (3) allocating non-hub nodes (terminals) to up to r-hubs, and (4) routing the pairwise o-d traffic. Typically, hub location problems include all four decisions while hub allocation problems assume that the valu…
Monads in double categories
2010
We extend the basic concepts of Street's formal theory of monads from the setting of 2-categories to that of double categories. In particular, we introduce the double category Mnd(C) of monads in a double category C and define what it means for a double category to admit the construction of free monads. Our main theorem shows that, under some mild conditions, a double category that is a framed bicategory admits the construction of free monads if its horizontal 2-category does. We apply this result to obtain double adjunctions which extend the adjunction between graphs and categories and the adjunction between polynomial endofunctors and polynomial monads.
A note on strong protomodularity, actions and quotients
2013
Abstract In order to study the problems of extending an action along a quotient of the acted object and along a quotient of the acting object, we investigate some properties of the fibration of points. In fact, we obtain a characterization of protomodular categories among quasi-pointed regular ones, and, in the semi-abelian case, a characterization of strong protomodular categories. Eventually, we return to the initial questions by stating the results in terms of internal actions.