630 research outputs found
Triviality of theory in a finite volume scheme adapted to the broken phase
We study the standard one-component -theory in four dimensions. A
renormalized coupling is defined in a finite size renormalization scheme which
becomes the standard scheme of the broken phase for large volumes. Numerical
simulations are reported using the worm algorithm in the limit of infinite bare
coupling. The cutoff dependence of the renormalized coupling closely follows
the perturbative Callan Symanzik equation and the triviality scenario is hence
further supported.Comment: 10 pages, 2 figure
Enhanced rationalisation, control or coordination? Impact assessments in the European Union
Impact assessment (IA) has attracted considerable attention in the worlds of research and practice. IA is discussed extensively and promoted widely as a means to enhance the rationalisation, control and coordination of policy-making. However, at the same time, there has also been disagreement based on whether IL is seen to reflect one single, or multiple rationales. This has, in turn, led to debates about whether particular IA experiences reflect one or a mixture
of motives. This thesis therefore explores whether the different ambitions or logics that IA intends to promote can be seen as complementary, whether one dominates, or whether they are contradictory. By looking at the European Union’s IA system — through an in-depth study of five IAS — this thesis finds that while the logic of enhanced control plays a dominant role throughout the policy-making process — particularly during the later policy-making stages —
the ambitions or logics of enhanced rationalisation and coordination also play distinct roles. This thesis thereby contributes to the debates about the use of 'meta-instruments' to address the three policy challenges of how to choose the 'best' policy option; how to steer public administrations; and how to coordinate policies across institutional sub-units. In doing so, the thesis departs from earlier studies on IA two significant ways. First, it examines IA as a set of procedural rules, therefore moving away from a focus on the role of the IA report in advancing (or failing to advance) the ambitions of enhanced control, rationalisation or coordination. Second, instead of examining each IA ambition or logic in isolation, this thesis acknowledges a multiplicity of ambitions. This multiplicity is not an aspect of diffusion across
jurisdictions or because of policy 'context'; rather, it is a feature of the motives and ambitions of actors interacting and changing at different stages in the policy-making process
Layered Drawing of Undirected Graphs with Generalized Port Constraints
The aim of this research is a practical method to draw cable plans of complex
machines. Such plans consist of electronic components and cables connecting
specific ports of the components. Since the machines are configured for each
client individually, cable plans need to be drawn automatically. The drawings
must be well readable so that technicians can use them to debug the machines.
In order to model plug sockets, we introduce port groups; within a group, ports
can change their position (which we use to improve the aesthetics of the
layout), but together the ports of a group must form a contiguous block.
We approach the problem of drawing such cable plans by extending the
well-known Sugiyama framework such that it incorporates ports and port groups.
Since the framework assumes directed graphs, we propose several ways to orient
the edges of the given undirected graph. We compare these methods
experimentally, both on real-world data and synthetic data that carefully
simulates real-world data. We measure the aesthetics of the resulting drawings
by counting bends and crossings. Using these metrics, we compare our approach
to Kieler [JVLC 2014], a library for drawing graphs in the presence of port
constraints.Comment: Appears in the Proceedings of the 28th International Symposium on
Graph Drawing and Network Visualization (GD 2020
Optimal Hormone Replacement Therapy in Hypothyroidism - A Model Predictive Control Approach
In this paper, we address the problem of optimal thyroid hormone replacement strategy development for hypothyroid patients. This is challenging for the following reasons. First, it is difficult to determine the correct dosage leading to normalized serum thyroid hormone concentrations of a patient. Second, it remains unclear whether a levothyroxine L-T4) monotherapy or a liothyronine/levothyroxine (L-T3/L-T4) combined therapy is more suitable to treat hypothyroidism. Third, the optimal intake frequency of L-T3/L-T4 is unclear. We address these issues by extending a mathematical model of the pituitary-thyroid feedback loop to be able to consider an oral intake of L-T3/L-T4. A model predictive controller (MPC) is employed to determine optimal dosages with respect to the thyroid hormone concentrations for each type of therapy. The results indicate that the L-T3/L-T4 combined therapy is slightly better (in terms of the achieved hormone concentrations) to treat hypothyroidism than the L-T4 monotherapy. In case of a specific genetic variant, namely genotype CC in polymorphism rs2235544 of gene DIO1, the simulation results suggest that the L-T4 monotherapy is better to treat hypothyroidism. In turn, when genotype AA is considered, the L-T3/L-T4 combined therapy is better to treat hypothyroidism. Furthermore, when genotype CC of polymorphism rs225014 (also referred to as c.274A>G or p.Thr92Ala) in the DIO2 gene is considered, the outcome of the L-T3/L-T4 combined therapy is better in terms of the steady-state hormone concentrations (for a triiodothyronine setpoint at the upper limit of the reference range of healthy individuals). Finally, the results suggest that two daily intakes of L-T3 could be the best trade-off between stable hormone concentrations and inconveniences for the patient. Copyright © 2022 Wolff, Dietrich and Müller
Outerplanar and Forest Storyplans
We study the problem of gradually representing a complex graph as a sequence
of drawings of small subgraphs whose union is the complex graph. The sequence
of drawings is called \emph{storyplan}, and each drawing in the sequence is
called a \emph{frame}. In an outerplanar storyplan, every frame is outerplanar;
in a forest storyplan, every frame is acyclic. We identify graph families that
admit such storyplans and families for which such storyplans do not always
exist. In the affirmative case, we present efficient algorithms that produce
straight-line storyplans.Comment: Appears in Proc. SOFSEM 202
Computing Height-Optimal Tangles Faster
We study the following combinatorial problem. Given a set of y-monotone
wires, a tangle determines the order of the wires on a number of horizontal
layers such that the orders of the wires on any two consecutive layers differ
only in swaps of neighboring wires. Given a multiset of swaps (that is,
unordered pairs of numbers between 1 and ) and an initial order of the
wires, a tangle realizes if each pair of wires changes its order exactly as
many times as specified by . The aim is to find a tangle that realizes
using the smallest number of layers. We show that this problem is NP-hard, and
we give an algorithm that computes an optimal tangle for wires and a given
list of swaps in time,
where is the golden ratio. We can treat lists where
every swap occurs at most once in time. We implemented the
algorithm for the general case and compared it to an existing algorithm.
Finally, we discuss feasibility for lists with a simple structure.Comment: Appears in the Proceedings of the 27th International Symposium on
Graph Drawing and Network Visualization (GD 2019
Inserts neu gedacht. Mittels 3D-Druck zum perfekt integrierten Insert!
Aus dem Leichtbau sind Sandwichstrukturen nicht mehr wegzudenken. Die
Gründe dafür liegen in ihrer hohen gewichtsbezogenen Biegesteifigkeit und
Beulstabilität. Üblicherweise bestehen Sandwichelemente aus zwei dünnen
zug- und druckfesten Deckschichten und einem dazwischen liegenden leichten und druckfesten Kern. Diese Kombination sorgt für die hervorragenden
Leichtbaueigenschaften. Das gilt besonders, wenn die Deckschichten aus
dünnen Kohlenstofffaser (CFK-)- oder Glasfaserkunststoffverbunden (GFK)
bestehen. Als Kernmaterialien kommen Waben oder Schäume aus Kunststoff
oder Metall sowie auch leichte Hölzer (z. B. Balsa) zur Anwendung. Eine
große Herausforderung bei der Sandwichbauweise sind jedoch die ansonsten
vielfach bewährten Schraubverbindungen. Denn bei Durchgangsverschraubungen besteht die Gefahr, den Kern zusammenzudrücken. Die am Institut
entwickelten Inserts lösen dieses Problem, indem sie die Kräfte gleichmäßig
einleiten, verteilen und eine Komprimierung des Kerns sicher verhindern
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