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2.
Gaussian null coordinates for rotating charged black holes and conserved charges
Mirjam Cvetič, Christopher N. Pope, Aritra Saha, Alejandro Satz, 2020, original scientific article

Abstract: Motivated by the study of conserved Aretakis charges for a scalar field on the horizon of an extremal black hole, we construct the metrics for certain classes of four-dimensional and five-dimensional extremal rotating black holes in Gaussian null coordinates. We obtain these as expansions in powers of the radial coordinate, up to sufficient order to be able to compute the Aretakis charges. The metrics we consider are for 4-charge black holes in four-dimensional STU supergravity (N = 2 supergravity coupled to three vector multiplets) (including the Kerr-Newman black hole in the equal-charge case) and the general 3-charge black holes in five-dimensional STU supergravity. We also investigate the circumstances under which the Aretakis charges of an extremal black hole can be mapped by conformal inversion of the metric into Newman-Penrose charges at null infinity. We show that while this works for four-dimensional static black holes, a simple radial inversion fails in rotating cases because a necessary conformal symmetry of the massless scalar equation breaks down. We also discuss that a massless scalar field in dimensions higher than four does not have any conserved Newman-Penrose charge, even in a static asymptotically flat spacetime.
Keywords: supergravitiy, flat spacetime, black hole, four-dimensional rotating, metrics
Published in DKUM: 16.10.2023; Views: 218; Downloads: 11
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3.
T-branes and G(2) backgrounds
Rodrigo Barbosa, Mirjam Cvetič, Jonathan J. Heckman, Craig Lawrie, Ethan Torres, Gianluca Zoccarato, 2020, original scientific article

Abstract: Compactification of M-string theory on manifolds with G(2) structure yields a wide variety of 4D and 3D physical theories. We analyze the local geometry of such compactifications as captured by a gauge theory obtained from a three-manifold of ADE singularities. Generic gauge theory solutions include a nontrivial gauge field flux as well as normal deformations to the three-manifold captured by noncommuting matrix coordinates, a signal of T-brane phenomena. Solutions of the 3D gauge theory on a three-manifold are given by a deformation of the Hitchin system on a marked Riemann surface which is fibered over an interval. We present explicit examples of such backgrounds as well as the profile of the corresponding zero modes for localized chiral matter. We also provide a purely algebraic prescription for characterizing localized matter for such T-brane configurations. The geometric interpretation of this gauge theory description provides a generalization of twisted connected sums with codimension seven singularities at localized regions of the geometry. It also indicates that geometric codimension six singularities can sometimes support 4D chiral matter due to physical structure "hidden" in T-branes.
Keywords: Yang-Mills connections, spin(7), holonomy, bundles, metrics
Published in DKUM: 16.10.2023; Views: 187; Downloads: 12
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4.
Effects of differential time and difficulty weighting on the improvement of OSCE quality metrics
Matic Mihevc, Klara Masnik, Tadej Petreski, Nejc Pulko, Sebastjan Bevc, 2022, original scientific article

Keywords: OSCE, clinical skills, peer assessment, quality metrics, weighting, outliers
Published in DKUM: 17.01.2023; Views: 367; Downloads: 45
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5.
Quantitative model for economic analyses of information security investment in an enterprise information system
Rok Bojanc, Borka Jerman-Blažič, 2012, original scientific article

Abstract: The paper presents a mathematical model for the optimal security-technology investment evaluation and decision-making processes based on the quantitative analysis of security risks and digital asset assessments in an enterprise. The model makes use of the quantitative analysis of different security measures that counteract individual risks by identifying the information system processes in an enterprise and the potential threats. The model comprises the target security levels for all identified business processes and the probability of a security accident together with the possible loss the enterprise may suffer. The selection of security technology is based on the efficiency of selected security measures. Economic metrics are applied for the efficiency assessment and comparative analysis of different protection technologies. Unlike the existing models for evaluation of the security investment, the proposed model allows direct comparison and quantitative assessment of different security measures. The model allows deep analyses and computations providing quantitative assessments of different options for investments, which translate into recommendations facilitating the selection of the best solution and the decision-making thereof. The model was tested using empirical examples with data from real business environment.
Keywords: modelling, security technology, economic metrics, investment, enterprise information system
Published in DKUM: 22.01.2018; Views: 1130; Downloads: 380
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6.
Usage, Potentials and Challenges of Building Information Modelling (BIM) in Slovenia, Austria, Germany and Switzerland
Amanda Jus, 2017, master's thesis

Abstract: In the master’s thesis, the main potentials, challenges and usage of Information Building Modelling (BIM) in Slovenia, Austria, Germany and Switzerland are presented, including its, because BIM is currently the most widely discussed topic in civil engineering. The study was based on a questionnaire that was carefully created at the HSLU (Hochschule Luzern) in Switzerland. We participated in the last phases of its development. With the help of the results of the questionnaire, we evaluated the current usage and acceptance of BIM among all participants in the building process.
Keywords: civil engineering, BIM, Building Information Modelling, BIM metrics
Published in DKUM: 25.09.2017; Views: 2086; Downloads: 235
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7.
XML Schema metrics for quality evaluation
Maja Pušnik, Marjan Heričko, Zoran Budimac, Boštjan Šumak, 2014, original scientific article

Abstract: In XML Schema development, the quality of XML Schemas is a crucial issue for further steps in the life cycle of an application, closely correlated with the structure of XML Schemas and different building blocks. Current research focuses on measuring complexity of XML Schemas and mainly do not consider other quality aspects. This paper proposes a novel quality measuring approach, based on existing software engineering metrics, additionally defining the quality aspects of XML Schemas using the following steps: (1) definition of six schema quality aspects, (2) adoption of 25 directly measurable XML Schema variables, (3) proposition of six composite metrics, applying 25 measured variables and (4) composite metrics validation. An experiment was conducted using 250 standard XML Schemas collected from available e-business information systems. The results illustrate the influence of XML Schemaʼs characteristics on its quality and evaluate the applicability of metrics in the measurement process, a useful tool for software developers while building or adopting XML Schemas.
Keywords: XML, metrics, quality variables, quality index, evaluation, validation
Published in DKUM: 06.07.2017; Views: 1319; Downloads: 401
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8.
On automata and language based grammar metrics
Matej Črepinšek, Tomaž Kosar, Marjan Mernik, Julien Cervelle, Rémi Forax, Gilles Roussel, 2010, original scientific article

Abstract: Grammar metrics have been introduced to measure the quality and the complexity of the formal grammars. The aim of this paper is to explore the meaning of these notions and to experiment, on several grammars of domain specific languages and of general-purpose languages, existing grammar metrics together with the new metrics that are based on grammar LR automaton and on the language recognized. We discuss the results of this experiment and focus on the comparison between grammars of domain specific languages as well as of general-purpose languages and on the evolution of the metrics between several versions of the same language.
Keywords: grammar metrics, software language engineering, grammar engineering, grammarware
Published in DKUM: 06.07.2017; Views: 1459; Downloads: 394
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9.
A programming language independent framework for metrics-based software evolution and analysis
Črt Gerlec, Gordana Rakić, Zoran Budimac, Marjan Heričko, 2012, original scientific article

Abstract: Knowledge about different aspects of software quality during software evolution can be valuable information for developers and project managers. It helps to reduce the number of defects and improves the internal structure of software. However, determining softwarećs quality and structure in heterogeneous systems is a difficult task. In this paper, a programming language independent framework for evaluating software metrics and analyzing software structure during software development and its evolution will be presented. The framework consists of the SMIILE tool for calculation of software metrics, extended with an analysis of software structure. The data are stored in a central repository via enriched Concrete Syntax Tree (eCST) for universal source code representation. The framework is demonstrated in a case study. The development of such a framework is a step forward to consistent support for software evolution by providing a change analysis and quality control. The significance of this consistency is growing today, when software projects are more complex, consisting of components developed in diverse programming languages.[Acknowledgments. Work of the second and third author is partially supported by the Serbian Ministry of Science and Technological Development through project no. OI174023 ĆIntelligent Techniquesand Their Integration into Wide-Spectrum Decision SupportĆ. Bilateral project between Slovenian Research Agency and Serbian Ministry of Science and Technological Development (Grant BI-SR/10-11-027) enabled the exchange of visits and ideas between authors of this paper and their institutions.]
Keywords: software evolution, software development, quality, structure, metrics
Published in DKUM: 06.07.2017; Views: 1961; Downloads: 366
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10.
Planar cell polarity genes frizzled4 and frizzled6 exert patterning influence on arterial vessel morphogenesis
Rene Markovič, Julien Peltan, Marko Gosak, Denis Horvat, Borut Žalik, Benjamin Seguy, Remi Chauvel, Gregoire Malandain, Thierry Couffinhal, Cécile Dupláa, Marko Marhl, Etienne Roux, original scientific article

Abstract: Quantitative analysis of the vascular network anatomy is critical for the understanding of the vasculature structure and function. In this study, we have combined microcomputed tomography (microCT) and computational analysis to provide quantitative three-dimensional geometrical and topological characterization of the normal kidney vasculature, and to investigate how 2 core genes of the Wnt/planar cell polarity, Frizzled4 and Frizzled6, affect vascular network morphogenesis. Experiments were performed on frizzled4 (Fzd4-/-) and frizzled6 (Fzd6-/-) deleted mice and littermate controls (WT) perfused with a contrast medium after euthanasia and exsanguination. The kidneys were scanned with a high-resolution (16 μm) microCT imaging system, followed by 3D reconstruction of the arterial vasculature. Computational treatment includes decomposition of 3D networks based on Diameter-Defined Strahler Order (DDSO). We have calculated quantitative (i) Global scale parameters, such as the volume of the vasculature and its fractal dimension (ii) Structural parameters depending on the DDSO hierarchical levels such as hierarchical ordering, diameter, length and branching angles of the vessel segments, and (iii) Functional parameters such as estimated resistance to blood flow alongside the vascular tree and average density of terminal arterioles. In normal kidneys, fractal dimension was 2.07±0.11 (n = 7), and was significantly lower in Fzd4-/- (1.71±0.04; n = 4), and Fzd6-/- (1.54±0.09; n = 3) kidneys. The DDSO number was 5 in WT and Fzd4-/-, and only 4 in Fzd6-/-. Scaling characteristics such as diameter and length of vessel segments were altered in mutants, whereas bifurcation angles were not different from WT. Fzd4 and Fzd6 deletion increased vessel resistance, calculated using the Hagen-Poiseuille equation, for each DDSO, and decreased the density and the homogeneity of the distal vessel segments. Our results show that our methodology is suitable for 3D quantitative characterization of vascular networks, and that Fzd4 and Fzd6 genes have a deep patterning effect on arterial vessel morphogenesis that may determine its functional efficiency.
Keywords: cell polarity, vascular network, metrics, quantitative analyses
Published in DKUM: 19.06.2017; Views: 1234; Downloads: 387
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