On the theta number of powers of cycle graphs

We give a closed formula for Lovasz theta number of the powers of cycle graphs and of their complements, the circular complete graphs. As a consequence, we establish that the circular chromatic number of a circular perfect graph is computable in polynomial time. We also derive an asymptotic estimate for this theta number.Comment: 17 page

Designing a standardised sampling method for invertebrate monitoringa : pilot experiment in a motorway retention pond

The implementation of the European Water Framework Directive revealed the necessity to develop new tools designed for freshwater ecosystems monitoring. As a new assessment approach employing invertebrate monitoring, three artificial substra­tes (two benthic and one pelagic) were tested for 7, 14,21 and 35 days of exposure in a motorway retention pond located in Southern France. Two of these artificial substrates appeared to sample too narrow a range of taxa, which was confirmed by two-way ANOVA tests and diversity and evenness indices. Samples taken by the remaining artificial substrate, composed of six plastic plant stems fixed on a 15 x 15 cm square tile, were representative of the species assemblage found in the stormwa­ter retention ponds. The use of an artificial substrate as a standardised method for long terro invertebrate monitoring in ponds holds much potential.La puesta en marcha de la Directiva Marco Europea del Agua requiere el desarrollo de nuevos protocolos de muestreo para el seguimiento de los ecosistemas acuáticos continentales. Como nuevas aproximaciones al seguimiento de invertebrados acuáticos se probaron tres sustratos artificiales (dos bénticos y uno pelágico) con un tiempo de exposición de 7, 14, 21 Y 35 días en una balsa de retención en una autopista del Sur de Francia. Dos de estos sustratos capturaron se1ectivamente un reducido número de taxones específicos, lo que fue confirmado con un análisis ANOVA de dos factores y los índices de diversidad y equitabilidad. Las muestras obtenidas con el sustrato artificial compuesto por seis pies de plantas de plástico fijadas en una baldosa cuadrada de 15 X 15 si que resultaron representativas de la asociación de especies característica de las balsas de retención de aguas en las autopistas. El uso de sustratos artificiales como método estandardizado para el seguimiento a largo plazo de los invertebrados acuáticos en balsas y charcas es de un gran potencial

Changes in Parasitoid Communities Over Time and Space: A Historical Case Study of the Maize Pest Ostrinia nubilalis

Understanding the ways in which human environmental modifications affect biodiversity is a key challenge in conservation planning, pest control and evolutionary ecology. Parasitoid communities, particularly those associated with agricultural pests, may be susceptible to such modifications. We document here changes in the larval parasitoid communities of Ostrinia nubilalis — the main pest of maize — and its sibling species O. scapulalis, based on two historical datasets, one collected from 1921–1928 and the other from 2001–2005. Each of these datasets encompasses several years and large geographical areas and was based on several thousands/millions of host larvae. The 80-year interval between the two datasets was marked by a decrease in O. nubilalis parasitism to about two thirds its initial level, mostly due to a decrease in the rate of parasitism by hymenopterans. However, a well balanced loss and gain of species ensured that species richness remained stable. Conversely, O. scapulalis displayed stable rates of parasitism over this period, with a decline in the species richness of its parasitoid community. Rates of parasitism and species richness in regions colonized by O. nubilalis during the 1950s were one half to one third those in regions displaying long-term colonisation by this pest. During the recent human activity-driven expansion of its range, O. nubilalis has neither captured native parasitoids nor triggered parasite spill back or spill over

Characterization of hydroxytyrosol-β-cyclodextrin complexes in solution and in the solid state, a potential bioactive ingredient

This study focused for the first time on characterizing the inclusion complexes between β-cyclodextrin (β-CD) and hydroxytyrosol (HT) in the solid state. In solution, HT and β-CD are able to form a 1:1 inclusion complex with an association constant of 33.2 ± 3.7 M-1. In the solid state, the inclusion complexes prepared by freeze-drying and spray-drying of an equimolar mixture of both partners were characterized and compared by 13C NMR and SEM. After dissolution, their free radical-scavenging ability was also determined by UV–visible spectroscopy. The results show that β-CD and drying processes have no effect on the efficiency of HT to reduce the DPPH radical. The solid state 13C NMR data provided information on the spatial proximity between β-CD and HT and suggest the formation of inclusion complexes for both drying processes compared to the physical mix. However, the morphology of the solids obtained was significantly different, as spherical particles were formed by spray-drying while freeze-drying only provided irregular shapes

Variability of Intensive Care Admission Decisions for the Very Elderly

Although increasing numbers of very elderly patients are requiring intensive care, few large sample studies have investigated ICU admission of very elderly patients. Data on pre triage by physicians from other specialities is limited. This observational cohort study aims at examining inter-hospital variability of ICU admission rates and its association with patients' outcomes. All patients over 80 years possibly qualifying for ICU admission who presented to the emergency departments (ED) of 15 hospitals in the Paris (France) area during a one-year period were prospectively included in the study. Main outcome measures were ICU eligibility, as assessed by the ED and ICU physicians; in-hospital mortality; and vital and functional status 6 months after the ED visit. 2646 patients (median age 86; interquartile range 83–91) were included in the study. 94% of participants completed follow-up (n = 2495). 12.4% (n = 329) of participants were deemed eligible for ICU admission by ED physicians and intensivists. The overall in-hospital and 6-month mortality rates were respectively 27.2% (n = 717) and 50.7% (n = 1264). At six months, 57.5% (n = 1433) of patients had died or had a functional deterioration. Rates of patients deemed eligible for ICU admission ranged from 5.6% to 38.8% across the participating centers, and this variability persisted after adjustment for patients' characteristics. Despite this variability, we found no association between level of ICU eligibility and either in-hospital death or six-month death or functional deterioration. In France, the likelihood that a very elderly person will be admitted to an ICU varies widely from one hospital to another. Influence of intensive care admission on patients' outcome remains unclear

Note on the sequence A157751

In this note, the following \href{http://oeis.org/A157751}{conjecture of Clark Kimberling}(?) is proved \begin{conjecture} Let $(F_n(X))_{n\in \N}$ be the sequence of polynomials defined by $F_n(X) = (X+1)F_{n-1}(X)+F_{n-1}(-X)$ with initial term $F_0(X) = 1$. If $n$ is even then $F_n(X)$ has no real roots, and if $n$ is odd then $F_n(X)$ has exactly one real root, denoted by $r$, and if n\ges 5 then $0 < -r < n$. \end{conjecture

Les méduses de Provence

Les méduses. Faut-il vraiment en avoir peur ? Et, si oui, pourquoi ? Que sait-on de ces « invertébrées » ? Comment ces animaux, à l’apparence si étrange, vivent-ils et se reproduisent-ils ? Dans ce livre très accessible, Alain Thiéry, chercheur à l’Institut méditerranéen de biodiversité et d’écologie, nous offre, en spécialiste réputé, une synthèse des connaissances actuelles. Il répertorie les espèces de méduses visibles en Provence et Méditerranée, explique les soins à porter en cas de « piqûre » et, surtout, restitue toute l’importance scientifique et culturelle de ces petites bêtes dont certaines propriétés, dûment exploitées, pourront nous aider à résister aux bouleversements climatiques en cours

La faune des mares temporaires, son originalité et son intérêt pour la biodiversité des eaux continentales méditerranéennes

The temporary ponds are inhabited by organisms able to adapt their life cycle to the fluctuating, unstable habitat. This distinctive feature determines the faunistical originality of this environment. The invertebrate communities of temporary ponds comprise two categories of species : -the migrant species, which are winged forms (insects) originating from permanent aquatic habitats, and which contribute to the first phase of colonisation, a short time after flooding. -the resident species, characterised by their life cycle taking place entirely in temporary aquatic habitats and always subjected to a period of drought. Crustaceans, which include most of the resident species, represent up to 90% of the total number of the animal community inhabiting temporary ponds. The colonisation of the neoformed biotops and the temporal dynamics of the animal communities were studied in detail in 9 significant stations.Les mares temporaires hébergent des organismes qui doivent s’adapter aux fluctuations de leur habitat. Cette particularité détermine l’originalité faunistique de ces milieux. Le peuplement d'invertébrés des mares temporaires comprend deux catégories d'espèces : -les espèces migrantes sont des formes ailées (insectes) provenant de milieux aquatiques permanents et qui participent à la colonisation des mares dès leur mise en eau. -les espèces résidentes dont tout le cycle biologique a lieu dans la mare temporaire ; elles se trouvent toujours confrontées à une période d’assec. Les Crustacés, qui constituent la majorité des espèces résidentes, réunissent plus de 90% de l’effectif total de la communauté animale peuplant ces mares. Ils représentent l’élément le plus caractéristique du peuplement car ils sont strictement inféodés à ce biotope par l’intermédiaire de leur écophase de résistance, l’œuf. La colonisation des milieux néoformés et la dynamique temporelle des communautés animales ont été analysées dans 9 stations significatives.Giudicelli Jean, Thiéry Alain. La faune des mares temporaires, son originalité et son intérêt pour la biodiversité des eaux continentales méditerranéennes. In: Ecologia mediterranea, tome 24 n°2, 1998. pp. 135-143

A new species of Tanymastigites Brtek, 1972 (Anostraca: Tanymastigidae) from Libya, with a revised key to the genus and new crustacean records (Branchiopoda, Copepoda, Ostracoda) from Algeria

International audienceAbstract The fairy shrimp Tanymastigites ajjeri n. sp. is described from a temporary water body, or guelta, in the Sahara Desert near the Tadrart mountains, east of Tassili n’Ajjer National Park, Libya. Males are readily separated from congeners by the morphology of the frontal appendages, which have an undivided lateral ramus and ≥ 0.4× the length of the medial ramus, and by the second antennae, in which the medial lamellar process bears a spatulate distal lobe. The new species is most similar to congeners T. perrieri (Daday, 1910) and T. mzabica (Gauthier, 1928), and it represents the sixth described species in this genus. We provide an updated key to the genus and comments on its diagnosis and definition, particularly concerning the descriptive terminology of the second antennae. In addition, we provide a list of new records of species of Branchiopoda, Copepoda, and Ostracoda from Tassili n’Ajjer National Park