Lombardi Drawings of Graphs

We introduce the notion of Lombardi graph drawings, named after the American abstract artist Mark Lombardi. In these drawings, edges are represented as circular arcs rather than as line segments or polylines, and the vertices have perfect angular resolution: the edges are equally spaced around each vertex. We describe algorithms for finding Lombardi drawings of regular graphs, graphs of bounded degeneracy, and certain families of planar graphs.Comment: Expanded version of paper appearing in the 18th International Symposium on Graph Drawing (GD 2010). 13 pages, 7 figure

The effects of caffeine on rugby passing accuracy while performing the Reactive Agility Test

This document is the Accepted Manuscript version of the following article: H. N. Assi, and L. Bottoms, ‘The effects of caffeine on rugby passing accuracy while performing the Reactive Agility Test’, Science & Sports, Vol. 29 (5): 275-281, October 2014, DOI: https://doi.org/10.1016/j.scispo.2014.07.012. This manuscript version is made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way.Aim.—Caffeine has been observed to improve performance of high-intensity and endurance exercise, but its effects on passing accuracy and reactive agility seen in intermittent high intensity team sports such as rugby and hockey are unclear. The purpose of this investigation was to determine the effect of ingesting caffeine on passing accuracy and agility speed before and after a simulated rugby protocol (SRP). Methods.—Nine male amateur rugby union players volunteered to participate in the study. The first visit participants undertook the multistage fitness test to estimate maximal oxygen consumption levels. On the second and third visits, a passing accuracy test (PAT) was undertaken which involved a modified reactive agility speed test that pressured the participants to pass into a target at the end of each run pre and post the 40-minute SRP. Participants ingested either 6 mg.kg.bw−1 of caffeine (CAF) or a placebo (PL) 60 minutes prior to the start of the SRP. Results.—CAF maintained sprint speed after the SRP whereas it decreased during PL trial. However, there were no effect of CAF on PAT scores (P > 0.05) nor was there an effect on RPE (P > 0.05). The results of the study lend some support to findings illustrating beneficial effect of caffeine ingestion before a simulated rugby protocol.Peer reviewe

Projected WIMP sensitivity of the LUX-ZEPLIN dark matter experiment

LUX-ZEPLIN (LZ) is a next-generation dark matter direct detection experiment that will operate 4850 feet underground at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. Using a two-phase xenon detector with an active mass of 7 tonnes, LZ will search primarily for low-energy interactions with weakly interacting massive particles (WIMPs), which are hypothesized to make up the dark matter in our galactic halo. In this paper, the projected WIMP sensitivity of LZ is presented based on the latest background estimates and simulations of the detector. For a 1000 live day run using a 5.6-tonne fiducial mass, LZ is projected to exclude at 90% confidence level spin-independent WIMP-nucleon cross sections above 1.4 × 10-48cm2 for a 40 GeV/c2 mass WIMP. Additionally, a 5σ discovery potential is projected, reaching cross sections below the exclusion limits of recent experiments. For spin-dependent WIMP-neutron(-proton) scattering, a sensitivity of 2.3 × 10−43 cm2 (7.1 × 10−42 cm2) for a 40 GeV/c2 mass WIMP is expected. With underground installation well underway, LZ is on track for commissioning at SURF in 2020

Measurement of the gamma ray background in the Davis Cavern at the Sanford Underground Research Facility

Deep underground environments are ideal for low background searches due to the attenuation of cosmic rays by passage through the earth. However, they are affected by backgrounds from γ-rays emitted by 40K and the 238U and 232Th decay chains in the surrounding rock. The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC located within the Davis campus at the Sanford Underground Research Facility, Lead, South Dakota, at the 4,850-foot level. In order to characterise the cavern background, in-situ γ-ray measurements were taken with a sodium iodide detector in various locations and with lead shielding. The integral count rates (0--3300~keV) varied from 596~Hz to 1355~Hz for unshielded measurements, corresponding to a total flux in the cavern of 1.9±0.4~γ cm−2s−1. The resulting activity in the walls of the cavern can be characterised as 220±60~Bq/kg of 40K, 29±15~Bq/kg of 238U, and 13±3~Bq/kg of 232Th

River discharge datasets for the coastlines of Scotland and Northern Ireland

Marine Scotland has commissioned Halcrow to provide a “Hydrodynamic model of Scottish shelf waters”. The overall aim of the project is to provide modelling evidence that can support planning of marine renewables and aquaculture within the Scottish shelf waters. Subsequently, the Centre for Ecology & Hydrology (CEH) has been commissioned by Marine Scotland to provide river discharge datasets for the coastlines of Scotland and Northern Ireland. Their supply is the subject of this report. The overall project is structured to include validation runs of the hydrodynamic shelf water model against observations of oceanographic quantities as well as producing climatic runs based on climatological forcing. Several detailed case study areas from across the Scottish shelf waters are also to be considered: these include Pentland Firth and Orkney Waters (PFOW), Loch Linnhe, Lewis and Harris, and St Magnus Bay, Shetland. A key component to the success of any hydrodynamic shelf water modelling approach is the availability of robust estimates of freshwater river discharges along the relevant coastal boundaries: in this case Scotland and Northern Ireland. In particular, successfully capturing the freshwater and sea water mixing process within the approach is important to achieve the salinity modelling objectives of the project. Observed river flows based on the river gauging station network operated by the Scottish Environment Protection Agency (SEPA) are considered as one source of data. However, there are limitations in the spatial and temporal coverage of this gauging network: in particular, Northern Ireland is not included. This leaves considerable “ungauged” areas that require some form of hydrological modelling in order to provide the coastal river discharges needed by the shelf water models. The Grid-to-Grid (G2G) distributed rainfall-runoff and routing model developed by CEH has been chosen to help provide the coastal river discharge datasets. G2G is already used for real-time flood forecasting across Great Britain at gauged and ungauged locations and has been extensively calibrated and assessed against river gauging station data. Although G2G is not currently used operationally over Northern Ireland, it was judged that the existing model configuration could be readily transferred based on experience of a previous transfer from England & Wales to Scotland. This is because the model formulation is underpinned by spatial datasets on soil, land-cover, geology and terrain for the chosen model domain. For long-term climatological simulations and for periods when observed flows are not available, G2G can be run in “simulation-mode” where gridded rainfall and potential evaporation (PE) time-series are converted into modelled river flows. For more recent periods when river flow data are available over Scotland, G2G can make full use of these data via “direct flow insertion”. This serves to route the available gauged river flows downstream whilst modelling any river flow contributions from ungauged areas using rainfall and PE inputs. This report initially reviews the background to the G2G model and its operational application across Scotland for the Scottish Flood Forecasting Service. Then a summary of the G2G model transfer to Northern Ireland is presented. The methodology used to specify the river discharge locations is outlined along with details of the river discharge datasets delivered. Datasets are supplied meeting the needs of both the climatological and validation runs of the Scottish shelf water hydrodynamic model

Edge Coloring of Bipartite Graphs with Constraints

It is a classical result from graph theory that the edges of an l--regular bipartite graph can be colored using exactly l colors so that edges that share an endpoint are assigned different colors. In this paper we study two constrained versions of the bipartite edge coloring problem. -- Some of the edges adjacent to a pair of opposite vertices of an l-regular bipartite graph are already colored with S colors that appear only on one edge (single colors) and D colors that appear in two edges (double colors). We show that the rest of the edges can be colored using at most maxfminfl+D; 3l 2 g; l + S+D 2 g total colors. We also show that this bound is tight by constructing instances in which maxfminfl +D; 3l 2 g; l + S+D 2 g colors are indeed necessary. -- Some of the edges of an l-regular bipartite graph are already colored with S colors that appear only on one edge. We show that the rest of the edges can be colored using at most maxfl+S=2; Sg total colors. We also show that ..