Landau-Migdal vs. Skyrme

The magnitude and density-dependence of the non-spin dependent Landau-Migdal parameters are derived from Skyrme energy functionals and compared with the phenomenological ones. We perform RPA calculations with various approximations for the Landau-Migdal particle-hole interaction and compare them with the results obtained with the full Skyrme interaction. For the first time the next to leading order in the Landau-Migdal approach is considered in nuclear structure calculations.Comment: Dedicated to the memory of G.E. Brow

Large-scale nuclear structure studies

The problem of microscopic nuclear structure theory in large single particle basis systems is reviewed. Several approaches are discussed, which attempt to approximate the large model spaces numerically inaccessible in complete shell model expansions of the nuclear wavefunctions. All of them use symmetry projected Hartree-Fock- Bogoliubov quasiparticle configurations as basic building blocks of the theory. They differ, however, in the degree of sophistication of the variational procedures which are used to determine the corresponding mean fields as well as the configuration mixing, up to a level, on which the construction of the configuration space itself is entirely left to the dynamics of the considered system. The mathematical formalism underlying these models is briefly summarised and the steps towards a numerical realisation are discussed. In several examples the possibilities and the power of the models are demonstrated and their limitations are shown. The models may provide a powerful tool for the analysis of experimental data as well as for predictions in still unexplored regions. On the other hand they may lead to a much better theoretical understanding of effective nuclear interactions as well as the underlying fundamental forces

Einsatzbereiche semantisch strukturierter Daten bei der Unternehmensanalyse

This dissertation consists of 6 papers. The papers investigate the areas of application of semantically structured data in company analysis. The first paper examines the extent to which alternative data can support tax audits. It is also important to understand how alternative data can be used in the first place. This includes the generation and further the processing of the data. Different meth-ods are presented for this purpose. The second paper deals with the quality of inline eXtensible Business Reporting Language (iXBRL) annual reports from the UK. Small and medium-sized enterpris-es (SMEs) have been required to make their annual reports available in iXBRL since 2011. These reports are both machine and human readable. This offers the possibil-ity to evaluate the annual reports of SMEs by machine. The study examines various dimensions of quality such as the structure of the tags. The analysis is important because the use of XBRL and iXBRL will still play an important role in the future, especially regarding the new European Single Electronic Format (ESEF) and the EU taxonomy for sustainable activities. The third paper analyzes iXBRL company accounts of SMEs in the UK. The infor-mation from the annual reports is processed automatically and linked to other data sources with the help of a knowledge graph. In this way, further information can be generated and processed. Other data sources are, for example, another database of the UK Companies House, but also other alternative data. Linking the data sources using the knowledge graph then enables the data to be queried, evaluated and visu-alized. The fourth paper deals with the question how connections between supervisory boards, management boards and auditors can be visualized with the help of the graph database Neo4j. Basically, the problem is that networks are difficult to ana-lyze and display. For this reason, this paper deals with the use of a graph database to close this gap. The database includes supervisory board members, management board members and auditors of DAX30 companies in 2019. With the help of Neo4j, the Curricula Vitae (CVs) are matched and the persons with common activities are analyzed. Among other things, multiple mandates, joint professional activities and joint training are examined. The fifth paper examines the collapse of the German financial services company Wirecard AG. The focus here is particularly on the people behind the scandal. For this purpose, the CV of the members of the supervisory board and the management board of the DAX30 companies are collected. The information is taken from the respective company websites. In addition, publicly available data sources are used to expand the database. The data is analyzed and visualized with the aid of a knowledge graph. In particular, the special features of the members of the supervi-sory board and the management board of Wirecard is addressed and the paper exam-ines the differences to other DAX30 companies in detail. The sixth paper is dedicated to teaching the basics of Resource Description Frame-work (RDF) and the RDF query language SPARQL. It has already been shown in the previous studies that the use of Knowledge Graphs can bring great benefits. In this paper, the concept of the WireGraph learning game is presented, which is used to teach business students how to work with knowledge graphs in order to work through the Wirecard scandal. For this purpose, a prosumer environment is provid-ed, with which the competence area of digital content creation of the reference model is taught completely and across all performance levels. In doing so, students not only learn the basics of RDF and SPARQL but can also apply them specifically to their ideas and further expertise. The conception of the learning game WireGraph is the first stage of a multi-stage project. The following steps are the development of the learning game and afterwards the application and the measurement of the di-dactic success.Die vorliegende Dissertation besteht aus 6 Beiträgen. Diese Beiträge untersuchen die Einsatzbereiche semantisch strukturierter Daten bei der Unternehmensanalyse. Die erste Studie untersucht, inwiefern „Alternative Data“ bei der Betriebsprüfung unterstützen können. Hierbei ist es auch wichtig zu verstehen, wie „Alternative Da-ta“ überhaupt genutzt werden können. Dazu zählen das Generieren und die Weiter-verarbeitung der Daten. Hierfür werden unterschiedliche Methoden dargestellt. Der zweite Beitrag beschäftigt sich mit der Qualität von inline eXtensible Business Reporting Language (iXBRL) Geschäftsberichten aus Großbritannien. Kleine und mittlere Unternehmen (KMU) müssen bereits seit 2011 ihre Geschäftsberichte in iXBRL zur Verfügung stellen. Diese Berichte sind sowohl maschinen- als auch menschenlesbar. Die Studie untersucht verschiedene Dimensionen der Qualität, wie beispielsweise die Struktur der Tags. Die Analyse ist wichtig, da die Verwendung von XBRL und iXBRL in der Zukunft, insbesondere im Hinblick auf ESEF und die EU-Verordnung für nachhaltige Aktivitäten, noch eine wichtige Rolle einnehmen wird. Der dritte Beitrag beschäftigt sich mit iXBRL Geschäftsberichten von KMU in Großbritannien. Die Informationen aus den Geschäftsberichten werden maschinell weiterverarbeitet und mithilfe eines Wissensgraphen mit anderen Datenquellen ver-knüpft. So können weitere Informationen generiert und verarbeitet werden. Andere Datenquellen sind beispielsweise eine weitere Datenbank des UK Companies House, aber auch andere „Alternative Data“. Die Verknüpfung der Datenquellen mittels Knowledge Graph ermöglicht anschließend die Abfrage, Auswertung und Visualisierung der Daten. Der vierte Beitrag beschäftigt sich mit der Frage, inwiefern Verbindungen zwischen Aufsichtsräten, Vorständen und Wirtschaftsprüfern mit Hilfe der Graph-Datenbank Neo4j visualisiert werden können. Grundsätzlich besteht das Problem, dass Vernet-zungen nur schwer zu analysieren und darzustellen sind. Aus diesem Grund beschäf-tigt sich dieser Beitrag mit der Verwendung einer Graph-Datenbank, um diese Lü-cke zu schließen. Die Datenbasis umfasst Aufsichtsräte, Vorstände und Wirtschafts-prüfer der DAX30-Unternehmen im Jahr 2019. Mithilfe von Neo4j werden die Lebensläufe abgeglichen und die Personen mit ge-meinsamen Tätigkeiten analysiert. Hierbei werden u.a. Mehrfachmandate, gemein-same berufliche Tätigkeiten und gemeinsame Ausbildung untersucht. Der fünfte Beitrag beschäftigt sich mit dem Zusammenbruch des deutschen Finanz-dienstleistungsunternehmens Wirecard AG, insbesondere mit den involvierten Per-sonen. Dafür werden die Lebensläufe der Mitglieder des Vorstands und des Auf-sichtsrats der DAX30-Unternehmen gesammelt. Die Informationen stammen aus den jeweiligen Unternehmenswebseiten. Zusätzlich werden öffentlich zugängliche Datenquellen genutzt, um die Datenbasis zu erweitern. Mithilfe eines Knowledge Graphs werden die Daten analysiert und visualisiert. Dabei wird insbesondere auf die Besonderheiten der Mitglieder des Vorstands und des Aufsichtsrats von Wire-card eingegangen und untersucht, ob und welche Unterschiede zu anderen DAX30-Unternehmen bestehen. Der sechste Beitrag widmet sich dem Lehren der Grundlagen des Resource Descrip-tion Frameworks (RDF) und der graphenbasierten Abfragesprache SPARQL. Bereits in den vorangehenden Studien konnte gezeigt werden, dass die Verwendung von Knowledge Graphs einen großen Nutzen bringen kann. In diesem Beitrag wird das Konzept des Lernspiels WireGraph vorgestellt, mit dem Studierende der Wirt-schaftswissenschaften die Arbeit mit Wissensgraphen erlernen, um den Wirecard-Skandal aufzuarbeiten. Dazu wird eine Prosumentenumgebung gestellt, mit der der Kompetenzbereich Erstellung digitaler Inhalte des Referenzmodells vollständig und über alle Leistungsniveaus hinweg vermittelt wird. Dabei erlernen Studierende nicht nur die Grundlagen von RDF und SPARQL, sondern können diese auch gezielt für ihre Ideen und ihr weiteres Fachwissen einsetzen

Spontaneous fission modes and lifetimes of super-heavy elements in the nuclear density functional theory

Lifetimes of super-heavy (SH) nuclei are primarily governed by alpha decay and spontaneous fission (SF). Here we study the competing decay modes of even-even SH isotopes with 108 <= Z <= 126 and 148 <= N <= 188 using the state-of-the-art self-consistent nuclear density functional theory framework capable of describing the competition between nuclear attraction and electrostatic repulsion. The collective mass tensor of the fissioning superfluid nucleus is computed by means of the cranking approximation to the adiabatic time-dependent Hartree-Fock-Bogoliubov approach. Along the path to fission, our calculations allow for the simultaneous breaking of axial and space inversion symmetries; this may result in lowering SF lifetimes by more than seven orders of magnitude in some cases. We predict two competing SF modes: reflection-symmetric and reflection-asymmetric.The shortest-lived SH isotopes decay by SF; they are expected to lie in a narrow corridor formed by $^{280}$Hs, $^{284}$Fl, and $^{284}_{118}$Uuo that separates the regions of SH nuclei synthesized in "cold fusion" and "hot fusion" reactions. The region of long-lived SH nuclei is expected to be centered on $^{294}$Ds with a total half-life of ?1.5 days.Comment: 6 pages, 4 figure

Self-consistent calculations within the Extended Theory of Finite Fermi Systems

The Extended Theory of Finite Fermi Systems(ETFFS) describes nuclear excitations considering phonons and pairing degrees of freedom, using experimental single particle energies and the effective Landau-Migdal interaction. Here we use the Skyrme interactions in order to extend the range of applicability of the ETFFS to experimentally not yet investigated short-lived isotopes. We find that Skyrme interactions which reproduce at the mean field level both ground state properties and nuclear excitations are able to describe the spreading widths of the giant resonances in the new approach, but produce shifts of the centroid energies. A renormalization of the Skyrme interactions is required for approaches going beyond the mean field level.Comment: 7 pages, 5 figures, corrected typo

Log-periodic self-similarity: an emerging financial law?

A hypothesis that the financial log-periodicity, cascading self-similarity through various time scales, carries signatures of a law is pursued. It is shown that the most significant historical financial events can be classified amazingly well using a single and unique value of the preferred scaling factor lambda=2, which indicates that its real value should be close to this number. This applies even to a declining decelerating log-periodic phase. Crucial in this connection is identification of a "super-bubble" (bubble on bubble) phenomenon. Identifying a potential "universal" preferred scaling factor, as undertaken here, may significantly improve the predictive power of the corresponding methodology. Several more specific related results include evidence that: (i) the real end of the high technology bubble on the stock market started (with a decelerating log-periodic draw down) in the begining of September 2000; (ii) a parallel 2000-2002 decline seen in the Standard & Poor's 500 from the log-periodic perspective is already of the same significance as the one of the early 1930s and of the late 1970s; (iii) all this points to a much more serious global crash in around 2025, of course from a level much higher (at least one order of magnitude) than in 2000.Comment: Talk given by S. Drozdz at International Econophysics Conference, Bali, August 28-31, 2002; typos correcte

Neutron rich nuclei in density dependent relativistic Hartree-Fock theory with isovector mesons

Density dependent relativistic Hartree-Fock theory has been extended to describe properties of exotic nuclei. The effects of Fock exchange terms and of pi - and rho - meson contributions are discussed. These effects are found to be more important for neutron rich nuclei than for nuclei near the valley of stability.Comment: 10 pages, 5 figures, LaTeX, macro packages graphicx and time

Self-consistent calculations of the electric giant dipole resonances in light and heavy mass nuclei

While bulk properties of stable nuclei are successfully reproduced by mean-field theories employing effective interactions, the dependence of the centroid energy of the electric giant dipole resonance on the nucleon number A is not. This problem is cured by considering many-particle correlations beyond mean-field theory, which we do within the "Quasiparticle Time Blocking Approximation". The electric giant dipole resonances in $^{16}$O, $^{40}$Ca, and $^{208}$Pb are calculated using two new Skyrme interactions.Comment: 4 pages, 4 figure

Decomposing the stock market intraday dynamics

The correlation matrix formalism is used to study temporal aspects of the stock market evolution. This formalism allows to decompose the financial dynamics into noise as well as into some coherent repeatable intraday structures. The present study is based on the high-frequency Deutsche Aktienindex (DAX) data over the time period between November 1997 and September 1999, and makes use of both, the corresponding returns as well as volatility variations. One principal conclusion is that a bulk of the stock market dynamics is governed by the uncorrelated noise-like processes. There exists however a small number of components of coherent short term repeatable structures in fluctuations that may generate some memory effects seen in the standard autocorrelation function analysis. Laws that govern fluctuations associated with those various components are different, which indicates an extremely complex character of the financial fluctuations.Comment: 15 pages, 13 PostScript figure