Locating Depots for Capacitated Vehicle Routing

We study a location-routing problem in the context of capacitated vehicle routing. The input is a set of demand locations in a metric space and a fleet of k vehicles each of capacity Q. The objective is to locate k depots, one for each vehicle, and compute routes for the vehicles so that all demands are satisfied and the total cost is minimized. Our main result is a constant-factor approximation algorithm for this problem. To achieve this result, we reduce to the k-median-forest problem, which generalizes both k-median and minimum spanning tree, and which might be of independent interest. We give a (3+c)-approximation algorithm for k-median-forest, which leads to a (12+c)-approximation algorithm for the above location-routing problem, for any constant c>0. The algorithm for k-median-forest is just t-swap local search, and we prove that it has locality gap 3+2/t; this generalizes the corresponding result known for k-median. Finally we consider the "non-uniform" k-median-forest problem which has different cost functions for the MST and k-median parts. We show that the locality gap for this problem is unbounded even under multi-swaps, which contrasts with the uniform case. Nevertheless, we obtain a constant-factor approximation algorithm, using an LP based approach.Comment: 12 pages, 1 figur

Interactions of technology and society: Impacts of improved airtransport. A study of airports at the grass roots

The feasibility of applying a particular conception of technology and social change to specific examples of technological development was investigated. The social and economic effects of improved airport capabilities on rural communities were examined. Factors which led to the successful implementation of a plan to construct sixty small airports in Ohio are explored and implications derived for forming public policies, evaluating air transportation development, and assessing technology

Staging power: a study of narrative patterns in Herodian’s history of the Roman Empire

This thesis explores the use of narrative patterns in Herodian’s History of the Roman Empire (third century AD), a work that covers in eight books the period between the death of Marcus Aurelius, in 180, and the accession of Gordian III, in 238. Drawing from narratological studies and literary theory, this dissertation provides a detailed analysis of the shape, function, and scope of the literary strategies used in the History. Aspects of Herodian’s narrative style that have often been criticized in modern scholarship (abundance of repetitions and formulae, indiscriminate use of classical models, excessive dramatization of events and characters) are re-examined through close readings of selected episodes. This is an investigatigation into the inner workings of Herodian’s storytelling and historiographical methods, in an effort to show that truth is not opposed to fiction, but both are key elements of the intellectual process inherent to the production of a historical text: through amplification, thematization, and arrangement, fiction, or invention, supplies raw facts with a density essential to any sort of deeper historical understanding. The narrativization of historical material is at the heart of this study.Fonds de recherche du Québec – Société et Culture (FRQSC); Social Sciences and Humanities Research Council of Canada (SSHRC-CRSH)Classics and Classical Civilizatio

Scientific Classification

types: ArticleN/

Three Lyα Emitting Galaxies within a Quasar Proximity Zone at z ~ 5.8

Quasar proximity zones at z > 5.5 correspond to overdense and overionized environments. Galaxies found inside proximity zones can therefore display features that would otherwise be masked by absorption in the intergalactic medium. We demonstrate the utility of this quasar-galaxy synergy by reporting the discovery of the first three “proximate Lyα emitters” (LAEs) within the proximity zone of quasar J0836+0054 at z = 5.795 (Aerith A, B, and C). Aerith A, located behind the quasar with an impact parameter D^{\perp} = 278 \pm 8 pkpc, provides the first detection of an Lyα transverse proximity effect. We model the transmission and show that it constrains the onset of J0836ʼs quasar phase to 0.2Myr < 28Myr < t in the past. The second object, Aerith B at a distance D < 912 pkpc from the quasar, displays a bright and broad double-peaked Lyα emission line. The peak separation implies a low ionizing f_{esc} \leqslant 1%. We fit the Lyα line with an outflowing shell model, finding a typical central density log N_{HI}/cm^{-2} = 19.3_{-0.2}^{+0.8}, outflow velocity v_{out} = 16_{-11}^{+4}km s^{-1}, and gas temperature log T/K = 3.8_{-0.7}^{+0.8} compared to 2 < z < 3 analog LAEs. We detect object Aerith C via an Lyα emission line at z = 5.726. This corresponds with the edge of the quasar’s proximity zone (Dz < 0.02), suggesting that the proximity zone is truncated by a density fluctuation. Via the analyses conducted here, we illustrate how proximate LAEs offer unique insight into the ionizing properties of both quasars and galaxies during hydrogen reionization

Vaccination par le BCG : enquête auprès d'enfants de moins de 5 ans consultant dans un service d'urgences hospitalières

International audienceFrance is a country with a low incidence of tuberculosis. However, there are important local variations: some parts of the city of Marseilles (southern France) presented a yearly incidence greater than 30/100,000 in 2010. The main goal of this study was to evaluate the BCG vaccine coverage among at-risk children younger than 5 years consulting in one of the city's pediatric emergency departments. Material and methods. This descriptive study took place in February 2013 and used a semi-directive questionnaire distributed to parents. Results. One hundred and thirty-five children were included, 98 (72.6 %) were considered as being at risk of tuberculosis and among them 75 (76.5 %, 95 % CI [68.0–85.1]) were vaccinated with BCG. Parents' knowledge of tuberculosis was relevant in 48 % of the respondents. Only 19 % of the parents reported that BCG protects against tuberculosis, but 73 % were in favor of this vaccination. Two criteria significantly increased vaccine coverage among at-risk children: birth in Marseilles and age more than 6 months on the consultation day. The child living in a poor family and type of medical follow-up did not significantly influence BCG vaccine coverage. Conclusion. BCG coverage was high in at-risk children younger than 5 years born in Marseilles. Cooperation between private physicians , maternity hospitals and mothers, and children's public health services probably facilitates this high level of protection.Malgré une faible incidence de la tuberculose en France, il existe de grandes variations à l'échelle communale : certains quartiers de Marseille présentent ainsi une incidence annuelle supérieure à 30/ 100 000. Le but de notre étude etait d'évaluer la couverture vaccinale par le vaccin de Calmette et Guérin (BCG) des enfants à risque aâgés de moins de 5 ans consultant dans un service d'urgences pédiatriques. Matériel et méthodes : Cette étude descriptive a eété réalisée en février 2013 à l'aide d'un questionnaire semi-directif proposé aux parents. Résultats : Cent-trente-cinq enfants ont été inclus, 98 (72,6 %) étaient considérés àrisque de tuberculose et parmi ces derniers 75 (76,5 %, IC 95 % [68,0–85,1]) eétaient vaccinés par le BCG. Seuls 48 % des parents connaissaient la tuberculose et 19 % savaient que le BCG protégeait contre cette maladie, mais 73 % étaient favorables à ce vaccin. Deux paramètres étaient liés à la vaccination des enfants à risque : une naissance à Marseille et un âge supérieur à 6 mois le jour de la consultation. La précarité des conditions de vie et le type de suivi médical n' influençaient pas significativement la couverture vaccinale des enfants à risque. Conclusion : En 2013, la couverture vaccinale par le BCG des enfants de moins de 5 ans nés à Marseille et à risque de tuberculose était correcte mais perfectible. Une coopération entre médecins de ville, maternités et services de protection maternelle et infantile (PMI) permet probablement d'obtenir cette bonne couverture vaccinale

The role of galaxies and AGN in reionising the IGM -- III : IGM-galaxy cross-correlations at z~6 from 8 quasar fields with DEIMOS and MUSE

We present improved results of the measurement of the correlation between galaxies and the intergalactic medium transmission at the end of reionization. We have gathered a sample of 13 spectroscopically confirmed Lyman-break galaxies (LBGs) and 21 Lyman-α emitters (LAEs) at angular separations 20 arcsec ≲ θ ≲ 10 arcmin (∼0.1–4 pMpc at z ∼ 6) from the sightlines to eight background z ≳ 6 quasars. We report for the first time the detection of an excess of Lyman-α transmission spikes at ∼10–60 cMpc from LAEs (3.2σ) and LBGs (1.9σ). We interpret the data with an improved model of the galaxy–Lyman-α transmission and two-point cross-correlations, which includes the enhanced photoionization due to clustered faint sources, enhanced gas densities around the central bright objects and spatial variations of the mean free path. The observed LAE(LBG)–Lyman-α transmission spike two-point cross-correlation function (2PCCF) constrains the luminosity-averaged escape fraction of all galaxies contributing to reionization to ⟨fesc⟩MUV−20(2σ)⁠) is necessary to reproduce the observed 2PCCF and that reionization might be driven by different sub-populations around LBGs and LAEs at z ∼ 6

EARL: Joint Entity and Relation Linking for Question Answering over Knowledge Graphs

Many question answering systems over knowledge graphs rely on entity and relation linking components in order to connect the natural language input to the underlying knowledge graph. Traditionally, entity linking and relation linking have been performed either as dependent sequential tasks or as independent parallel tasks. In this paper, we propose a framework called EARL, which performs entity linking and relation linking as a joint task. EARL implements two different solution strategies for which we provide a comparative analysis in this paper: The first strategy is a formalisation of the joint entity and relation linking tasks as an instance of the Generalised Travelling Salesman Problem (GTSP). In order to be computationally feasible, we employ approximate GTSP solvers. The second strategy uses machine learning in order to exploit the connection density between nodes in the knowledge graph. It relies on three base features and re-ranking steps in order to predict entities and relations. We compare the strategies and evaluate them on a dataset with 5000 questions. Both strategies significantly outperform the current state-of-the-art approaches for entity and relation linking.Comment: International Semantic Web Conference 201

A zeta function approach to the relation between the numbers of symmetry planes and axes of a polytope

A derivation of the Ces\`aro-Fedorov relation from the Selberg trace formula on an orbifolded 2-sphere is elaborated and extended to higher dimensions using the known heat-kernel coefficients for manifolds with piecewise-linear boundaries. Several results are obtained that relate the coefficients, $b_i$, in the Shephard-Todd polynomial to the geometry of the fundamental domain. For the 3-sphere we show that $b_4$ is given by the ratio of the volume of the fundamental tetrahedron to its Schl\"afli reciprocal.Comment: Plain TeX, 26 pages (eqn. (86) corrected