A Trichotomy for Regular Trail Queries

Regular path queries (RPQs) are an essential component of graph query languages. Such queries consider a regular expression r and a directed edge-labeled graph G and search for paths in G for which the sequence of labels is in the language of r. In order to avoid having to consider infinitely many paths, some database engines restrict such paths to be trails, that is, they only consider paths without repeated edges. In this paper we consider the evaluation problem for RPQs under trail semantics, in the case where the expression is fixed. We show that, in this setting, there exists a trichotomy. More precisely, the complexity of RPQ evaluation divides the regular languages into the finite languages, the class T_tract (for which the problem is tractable), and the rest. Interestingly, the tractable class in the trichotomy is larger than for the trichotomy for simple paths, discovered by Bagan et al. [Bagan et al., 2013]. In addition to this trichotomy result, we also study characterizations of the tractable class, its expressivity, the recognition problem, closure properties, and show how the decision problem can be extended to the enumeration problem, which is relevant to practice

Robust solutions of bi-blend recipe optimization with quadratic constraints

Production companies use raw materials to compose end-products. They often make different products with the same raw materials. In this research, the focus lies on the production of two end-products consisting of (partly) the same raw materials as cheap as possible. Each of the products has its own demand and quality requirements consisting of quadratic constraints. The minimization of the costs, given the quadratic constraints is a global optimization problem, which can be difficult because of possible local optima. Therefore, the multi modal character of the (bi-) blend problem is investigated. Standard optimization packages (solvers) in Matlab and GAMS were tested on their ability to solve the problem. In total 20 test cases were generated and taken from literature to test solvers on their effectiveness and efficiency to solve the problem. The research also gives insight in adjusting the quadratic constraints of the problem in order to make a robust problem formulation of the bi-blend problem

Antimicrobial susceptibility testing of dermatophytes - Comparison of the agar macrodilution and broth microdilution tests

Fifty dermatophyte strains, recently obtained from clinical material, belonging to 4 different species were examined for their susceptibility to 5 systemic or topical antimycotic agents using both an agar macrodilution and a broth microdilution test. Antimycotics compared were griseofulvin, itraconazole, sertaconazole, terbinafine and ciclopiroxolamine. A comparison of the minimum inhibitory concentrations (MIC) clearly showed differences between the two test methods applied. For all 5 antimycotics, MIC data were three- to seventyfold lower in the microdilution test system. These differences, depending on the test method, have to be taken into account when comparing MIC data in the literature or when relating the in vitro data to the tissue concentrations determined in vivo

Modelling of just-submerged and submerged flexible vegetation

Paper ist part of "Abstract Book" which is available online: https://iahr2020.pl/wp-content/uploads/2021/03/IAHR_2020_book_of_abstracts_final.pd

Dinge - Nutzer - Netze: Von der Virtualisierung des Musealen zur Musealisierung des Virtuellen

Museen sind stets auch virtuelle Räume: Als Einrichtungen des gemeinsamen Erinnerns schlagen sie Brücken zwischen dem An- und Abwesenden, der Materialität ihrer Exponate und einer Vergangenheit, die nur in ihren Hinterlassenschaften ihr Wirklichsein zu behaupten vermag. Dennoch sind in einer Gesellschaft, für die Virtualität Normalität geworden ist, die Institution Museum und ihr Umgang mit den längst nicht mehr 'neuen' Medien nach wie vor Austragungsorte erhitzter Debatten über das 'Echte', das 'Authentische' und die Erfahrbarkeit des Wirklichen. Dennis Niewerth geht der Frage nach, worin die "Virtualisierung des Musealen" besteht. Und er zeigt, was das Museum als Bollwerk der Kulturpädagogik im Sinne einer "Musealisierung des Virtuellen" einer Gesellschaft anzubieten hat, die unter der Fülle ihrer Erinnerungen begraben zu werden droht

Dinge – Nutzer – Netze

Museums have always been virtual places – so why do these institutions find it so difficult to use digital media? And what does a museum have to offer to a knowledge-based society whose act of remembering increasingly takes place in the digital domain?Museen sind stets auch virtuelle Räume: Als Einrichtungen des gemeinsamen Erinnerns schlagen sie Brücken zwischen dem An- und Abwesenden, der Materialität ihrer Exponate und einer Vergangenheit, die nur in ihren Hinterlassenschaften ihr Wirklichsein zu behaupten vermag. Dennoch sind in einer Gesellschaft, für die Virtualität Normalität geworden ist, die Institution Museum und ihr Umgang mit den längst nicht mehr ›neuen‹ Medien nach wie vor Austragungsorte erhitzter Debatten über das ›Echte‹, das ›Authentische‹ und die Erfahrbarkeit des Wirklichen. Dennis Niewerth geht der Frage nach, worin die »Virtualisierung des Musealen« besteht. Und er zeigt, was das Museum als Bollwerk der Kulturpädagogik im Sinne einer »Musealisierung des Virtuellen« einer Gesellschaft anzubieten hat, die unter der Fülle ihrer Erinnerungen begraben zu werden droht