Partitioning Graph Drawings and Triangulated Simple Polygons into Greedily Routable Regions

A greedily routable region (GRR) is a closed subset of $\mathbb R^2$, in which each destination point can be reached from each starting point by choosing the direction with maximum reduction of the distance to the destination in each point of the path. Recently, Tan and Kermarrec proposed a geographic routing protocol for dense wireless sensor networks based on decomposing the network area into a small number of interior-disjoint GRRs. They showed that minimum decomposition is NP-hard for polygons with holes. We consider minimum GRR decomposition for plane straight-line drawings of graphs. Here, GRRs coincide with self-approaching drawings of trees, a drawing style which has become a popular research topic in graph drawing. We show that minimum decomposition is still NP-hard for graphs with cycles, but can be solved optimally for trees in polynomial time. Additionally, we give a 2-approximation for simple polygons, if a given triangulation has to be respected.Comment: full version of a paper appearing in ISAAC 201

Many-to-One Boundary Labeling with Backbones

In this paper we study \emph{many-to-one boundary labeling with backbone leaders}. In this new many-to-one model, a horizontal backbone reaches out of each label into the feature-enclosing rectangle. Feature points that need to be connected to this label are linked via vertical line segments to the backbone. We present dynamic programming algorithms for label number and total leader length minimization of crossing-free backbone labelings. When crossings are allowed, we aim to obtain solutions with the minimum number of crossings. This can be achieved efficiently in the case of fixed label order, however, in the case of flexible label order we show that minimizing the number of leader crossings is NP-hard.Comment: 23 pages, 10 figures, this is the full version of a paper that is about to appear in GD'1

Operating Power Grids with Few Flow Control Buses

Future power grids will offer enhanced controllability due to the increased availability of power flow control units (FACTS). As the installation of control units in the grid is an expensive investment, we are interested in using few controllers to achieve high controllability. In particular, two questions arise: How many flow control buses are necessary to obtain globally optimal power flows? And if fewer flow control buses are available, what can we achieve with them? Using steady state IEEE benchmark data sets, we explore experimentally that already a small number of controllers placed at certain grid buses suffices to achieve globally optimal power flows. We present a graph-theoretic explanation for this behavior. To answer the second question we perform a set of experiments that explore the existence and costs of feasible power flow solutions at increased loads with respect to the number of flow control buses in the grid. We observe that adding a small number of flow control buses reduces the flow costs and extends the existence of feasible solutions at increased load.Comment: extended version of an ACM e-Energy 2015 poster/workshop pape

The compressibility of graphene

We present a review of the electronic compressibility of monolayer and bilayer graphene. We focus on describing theoretical calculations of the effects of electron--electron interactions and various types of disorder, and also give a summary of current experiments and describe which aspects of theory they support. We also include a full analysis of all commonly-used contributions to the tight-binding Hamiltonian of bilayer graphene and their effects on the compressibility.Comment: 15 preprint-style pages, 5 figure

Разработка и исследование измерительной оптической системы для проведения гемореологических исследований в малых объемах

В данной работе будут проводиться исследования по изучению оптических свойств капельных образцов биологических жидкостей для решения задач диагностики в области клинического лабораторного анализа. В ходе исследования будут рассмотрены вопросы по оценке влияния сдвиговых напряжений на образец с биологической жидкостью, а также исследованы методы и способы расчета влияния сдвиговых напряжений на биологические жидкости.In this paper, research will be conducted to study the optical properties of drip samples of biological fluids for diagnostics in the field of clinical laboratory analysis. The study will focus on assessing the impact of shear stress on a sample with biological fluid, and studied methods and ways of calculation of the influence of shear stress on biological fluids

The impact of UK soft drinks industry levy on manufacturers’ domestic turnover

In March 2016, the UK government announced the Soft Drinks Industry Levy (SDIL) which came into effect in April 2018. In common with the reaction to sugar-sweetened beverage (SSB) taxes in other countries, the SDIL announcement was met with strong industry opposition, with claims that it would harm their profits. The SDIL was designed to incentivise reformulation of SSBs by providing a 2-year delay between the announcement and the enforcement of the levy, and adopting a two-tiered rate based on the sugar content of the drinks. Using interrupted time series analysis, this paper examines how the domestic turnover of UK soft drinks manufacturers changed after the announcement and the implementation of the SDIL. Our results show some evidence of a short-term negative impact of the SDIL announcement on the domestic turnover of the UK soft drinks manufacturers. This effect, however, did not continue post-implementation. These findings suggest that manufacturers were, to a large extent, able to mitigate the effects of levy before it came into effect

What can we learn from patients with heart failure about exercise adherence? A systematic review of qualitative papers

SCT may be a useful framework for developing interventions to support patients with HF in undertaking and maintaining regular exercise patterns. Specific components of SCT that practitioners may wish to consider include self-efficacy and outcome expectancies. These were issues referred to in papers for the systematic review that appear to be particularly related to exercise adherence