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Search Results: 1 - 10 of 33826 matches for " Nils Daniel "
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Computing Khovanov-Rozansky homology and defect fusion
Nils Carqueville,Daniel Murfet
Mathematics , 2011, DOI: 10.2140/agt.2014.14.489
Abstract: We compute the categorified sl(N) link invariants as defined by Khovanov and Rozansky, for various links and values of N. This is made tractable by an algorithm for reducing tensor products of matrix factorisations to finite rank, which we implement in the computer algebra package Singular.
Adjunctions and defects in Landau-Ginzburg models
Nils Carqueville,Daniel Murfet
Mathematics , 2012, DOI: 10.1016/j.aim.2015.03.033
Abstract: We study the bicategory of Landau-Ginzburg models, which has potentials as objects and matrix factorisations as 1-morphisms. Our main result is the existence of adjoints in this bicategory and a description of evaluation and coevaluation maps in terms of Atiyah classes and homological perturbation. The bicategorical perspective offers a unified approach to Landau-Ginzburg models: we show how to compute arbitrary correlators and recover the full structure of open/closed TFT, including the Kapustin-Li disk correlator and a simple proof of the Cardy condition, in terms of defect operators which in turn are directly computable from the adjunctions.
A toolkit for defect computations in Landau-Ginzburg models
Nils Carqueville,Daniel Murfet
Mathematics , 2013,
Abstract: We review the results of arXiv:1208.1481 on orientation reversal and duality for defects in topological Landau-Ginzburg models, with the intention of providing an easily accessible toolkit for computations. As an example we include a proof of the main result on adjunctions in a special case, using Pauli matrices. We also explain how to compute arbitrary correlators of defect-decorated planar worldsheets, and briefly discuss the relation to generalised orbifolds.
A quick guide to defect orbifolds
Ilka Brunner,Nils Carqueville,Daniel Plencner
Mathematics , 2013,
Abstract: We provide a lightning review of the construction of (generalised) orbifolds [arXiv:0909.5013, arXiv:1210.6363] of two-dimensional quantum field theories in terms of topological defects, along the lines of [arXiv:1307.3141]. This universal perspective has many applications, some of which we sketch in the examples of 2d Yang-Mills theory, Landau-Ginzburg models, and rational CFT.
Discrete torsion defects
Ilka Brunner,Nils Carqueville,Daniel Plencner
Mathematics , 2014, DOI: 10.1007/s00220-015-2297-9
Abstract: Orbifolding two-dimensional quantum field theories by a symmetry group can involve a choice of discrete torsion. We apply the general formalism of `orbifolding defects' to study and elucidate discrete torsion for topological field theories. In the case of Landau-Ginzburg models only the bulk sector had been studied previously, and we re-derive all known results. We also introduce the notion of `projective matrix factorisations', show how they naturally describe boundary and defect sectors, and we further illustrate the efficiency of the defect-based approach by explicitly computing RR charges. Roughly half of our results are not restricted to Landau-Ginzburg models but hold more generally, for any topological field theory. In particular we prove that for a pivotal bicategory, any two objects of its orbifold completion that have the same base are orbifold equivalent. Equivalently, from any orbifold theory (including those based on nonabelian groups) the original unorbifolded theory can be obtained by orbifolding via the `quantum symmetry defect'.
Orbifolds and topological defects
Ilka Brunner,Nils Carqueville,Daniel Plencner
Mathematics , 2013, DOI: 10.1007/s00220-014-2056-3
Abstract: We study orbifolds of two-dimensional topological field theories using defects. If the TFT arises as the twist of a superconformal field theory, we recover results on the Neveu-Schwarz and Ramond sectors of the orbifold theory as well as bulk-boundary correlators from a novel, universal perspective. This entails a structure somewhat weaker than ordinary TFT, which however still describes a sector of the underlying conformal theory. The case of B-twisted Landau-Ginzburg models is discussed in detail, where we compute charge vectors and superpotential terms for B-type branes. Our construction also works in the absence of supersymmetry and for generalised "orbifolds" that need not arise from symmetry groups. In general this involves a natural appearance of Hochschild (co)homology in a 2-categorical setting, in which among other things we provide simple presentations of Serre functors and a further generalisation of the Cardy condition.
Energy Dissipation Within the Wave Run-Up at Stepped Revetments Energy Dissipation Within the Wave Run-Up at Stepped Revetments
KERPEN Nils B.,BUNG Daniel B.,VALERO Daniel,SCHLURMANN Torsten
- , 2017,
Abstract: To understand the processes and energy dissipation performance caused by turbulence during the wave run-up over a stepped revetment,hydraulic model tests with steady flow conditions are conducted and correlated with unsteady flow conditions of the wave run-up within a short time frame.Under irregular waves,the run-up reduction over a stepped revetment is dependent on the Iribarren number and decreases for decreasing Iribarren numbers.Velocity gradients are found to be similar in a steady and unsteady flow regime near the pseudo-bottom
H modynamische Analyse und Klassifikation der Gef strukturen bei Patienten mit zerebralen arterioven sen Malformationen
Forkert, Nils Daniel,S?ring, Dennis,Fiehler, Jens,Illies, Till
GMS Medizinische Informatik, Biometrie und Epidemiologie , 2009,
Abstract: Hintergrund: Eine zerebrale arterioven se Malformation (AVM) ist eine Gef missbildung im Gehirn, die sich durch das Fehlen eines kapillaren Gef bettes mit abnormem Kurzschluss zwischen dem arteriellen und dem folgendem ven sen System auszeichnet, dem sog. Nidus. Die ver nderten h modynamischen Bedingungen resultieren in neurologischen Ausf llen sowie in dysplastischen Ver nderungen der zu- und abführenden Gef e und daraus folgenden erh hten Blutungsrisiko. Zielsetzung: Für die diagnostische Beurteilung der AVM sind Informationen über die individuelle Gef struktur und die H modynamik von besonderem Interesse. In diesem Beitrag wird ein Verfahren zur Extraktion von Parametern zur Beschreibung der H modynamik pr sentiert. Aufbauend hierauf werden Verfahren zur automatischen Detektion des Nidus der arterioven sen Malformation sowie der zuleitenden (Feeder), ableitenden (Drainagevenen) und en passage“-Gef e vorgestellt. Als Eingabe hierfür dienen hochaufgel ste 3D- sowie zeitlich-r umliche 4D-MRT-Bildsequenzen. Methoden: Bei der vorgestellten Methode wird zun chst in den 3D-MRT-Bilddaten das Gef system semi-automatisch segmentiert. Auf Basis eines neuen Verfahrens zur Charakterisierung der H modynamik durch Bestimmung des Einflusszeitpunktes des Kontrastmittels mittels referenzbasierter Kurvenanpassung wird in einem weiteren Schritt in den zeitlich-r umlichen MR-Bildfolgen für jedes Voxel der zeitliche Signalverlauf analysiert. Zus tzlich wird die Flussgeschwindigkeit des Kontrastmittels diskret approximiert. Anschlie end werden die extrahierten Parameterbilder mittels eines nicht-linearen Registrierungsverfahrens automatisch auf das segmentierte Gef system übertragen. Durch eine kombinierte Analyse der Intensit t, der Geschwindigkeit und des relativen Einflusszeitpunktes des Blutes werden Gef strukturen automatisch charakterisiert. Ergebnisse: Zur Evaluation der vorgestellte Methode standen 19 Datens tze von Patienten mit diagnostizierter AVM zur Verfügung. Durch Anwendung der neuen Methode zur Beschreibung der Einstr mzeitpunkte konnten Artefakte in Form von starken zeitlichen Sprüngen zwischen den Einflusszeitpunkten benachbarter Voxel deutlich verringert werden. Die Detektion des Nidus wurde anhand von manuellen Segmentierungen validiert und ergab eine mittlere Volumenübereinstimmung von ca. 88%. Drainagevenen und Feeder konnten mit einer Genauigkeit von 95% detektiert werden. Schlussfolgerung: Die vorgestellte Methode erm glicht eine robuste automatische Detektion des AVM-Nidus sowie eine Klassifikation der Gef e. Eine visuelle Begutachtung du
Pracital examination in biochemistry: topics and procedures?
Vocke, Nils-Daniel,Zwinger, Matthias,Koolman, Jan
GMS Zeitschrift für Medizinische Ausbildung , 2005,
Abstract: Under the new revision of the German licensing regulations for physicians ("Approbationsordnung") the rules for the first national examinations (i.e. "Physikum", equivalent to medical school entrance exams) have been changed. In addition to the written exam a novel "oral-practical" part is required. Here we describe the implications of this oral-practical exam on the examination procedures in the field of biochemistry/molecular biology. A strategy for its realization is proposed.
A Study of Personality and Family- and School Environment and Possible Interactional Effects in 244 Swedish Children—A Multiple Regression Analysis  [PDF]
Nils Bertil Gerhard Persson
Psychology (PSYCH) , 2014, DOI: 10.4236/psych.2014.58100
Abstract:

The aim of the study was to examine relationships between psychosocial family- and school environment and personality as assessed by the Junior Eysenck Personality Questionnaire (EPQ-J) and possible personality interactional effects. The study was based on 244 Swedish girls and boys, 10 - 19 years old, who filled in the Family- and School Psychosocial Environment (FSPE) questionnaire and the EPQ-J. A multiple regression analysis showed that the FSPE-factor family conflicts and school discipline predicts psychoticism (antisocial personality), and that the FSPE-factor warmth, support and openness from parents, siblings and peers predict extraversion. Sex, psychoticism and the size of sibling group predicted neuroticism. Spanking was reported in various degrees by 8.1 percent of the children, and this factor was related to psychoticism. These results support socialization theories. The most unexpected finding was the impact of interactions between personality variables themselves, influencing the FSPE’s predictability of neuroticism. Discussion about the advantage of the use of statistic control in a multiple regression, possible causal links between psychosocial environment and personality, limitations and further research propositions concludes the article.

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