Comparison of three management schemes for Colorado potato beetle on early-season potatoes in Prince Edward Island

Les aspects économiques de la lutte au doryphore de la pomme de terre, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) sur la pomme de terre (Solanum tuberosum) à l'aide de diverses stratégies ont été étudiés à quatre localités de l'île du Prince-Édouard en 1989. Trois traitements ont été essayés à chaque endroit: 1) une parcelle-témoin non traitée; 2) l'application du Bacillus thuringiensis var. tenebrionis ou de roténone après l'atteinte d'un seuil de 0,5 équivalent de doryphore de la pomme de terre (EDPT) par tige (1 EDPT = 1 adulte du printemps, 8 larves de premier ou second stade, 3 larves de troisième ou quatrième stade ou 1,6 adultes de l'été) ; 3) l'application d'insecticides selon le programme régulier de pulvérisation des producteurs. À une des localités, le rendement en tubercules des parcelles gérées avec le seuil de 0,5 EDPT par tige a été similaire à celui obtenu des parcelles pour lesquelles le producteur maintenait son programme régulier de pulvérisation, mais trois applications d'insecticides en moins ont été utilisées dans le premier cas. Aux autres localités pour lesquelles la densité de doryphores de la pomme de terre n'a pas excédé le seuil de traitement, le rendement en tubercules a été similaire à celui des autres parcelles des producteurs. Ces résultats indiquent qu'il y a eu des applications superflues d'insecticides par les producteurs.The economics of managing the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) on potatoes (Solarium tuberosum) with different strategies was tested at four sites on Prince-Edward-Island in 1989. Three treatments were tested at each site: 1) an untreated check, 2) an application of Bacillus thuringiensis var. tenebrionis or rotenone after a threshold of 0.5 Colorado Potato Beetle Equivalents (CPBE) per stalk was reached ( 1 CPBE = 1 spring adult, 8 first- or second- instar larvae, 3 third- or fourth- instar larvae, or 1.6 summer adults), and 3) applications of insecticide according to the grower's normal spray schedule. At one site, tuber yield of plots managed with the 0.5 CPBE-per-stalk threshold was similar to that of plots where the grower maintained his normal spray schedule, but three fewer applications of insecticides were needed in the former. At the remaining sites, where the density of Colorado potato beetles did not exceed the threshold, tuber yield was similar to that of the grower's plots. This suggests that there were needless applications of insecticides by the growers

The location of egg masses of Ostrinia nubilalis [Lepidoptera : Pyralidae] on potato plants

La position des masses d'oeufs de la pyrale du maïs, Ostrinia nubilalis, a été étudiée sur des pommes de terre (Solanum tuberosum) 'Russet Burbank' cultivées à l'île-du-Prince-Édouard (Canada) de 1990 à 1992. La position sur la plante de 315 masses d'oeufs a été caractérisée par l'examen d'environ 3700 plantes. Dans le deux tiers inférieur des plantes se retrouvaient 92 % des masses d'oeufs, tandis que 95 % des masses d'oeufs se localisaient sur la face inférieure des folioles et sur les tiges. Dans l'ensemble, 88 % des masses d'oeufs se retrouvaient dans le deux tiers inférieur des plantes, à la fois sur les tiges et sur la face inférieure des folioles. La période d'échantillonnage pourra être optimisée si les personnes qui effectuent le dépistage concentrent leurs efforts seulement sur le deux tiers inférieur des tiges, lequel représente seulement 3,7 % de la surface totale de la fane mais contient 50 % des masses d'oeufs.The location of egg masses of the European corn borer, Ostrinia nubilalis, was studied on potatoes (Solanum tuberosum) “Russet Burbank” grown on Prince-Edward-Island, Canada, from 1990 to 1992. The within-plant positions of 315 egg masses were characterized by the examination of approximately 3700 plants. Ninety-two percent of the egg masses were found on the bottom two-thirds of the plants and 95% were found on the underside of the leaflets and on the stalks. In total, 88% of the egg masses were found on the bottom two-thirds of the plants on both the stalks and the underside of the leaflets. Sampling time can be optimized if the people engaged in scouting programs concentrate their efforts on the bottom two-thirds of the stalks alone, which represents only 3.7% of the total surface area of the haulm but contains 50% of the egg masses

Linear Field Dependence of the Normal-State In-Plane Magnetoresistance of Sr2RuO4

The transverse and longitudinal in-plane magnetoresistances in the normal state of superconducting Sr2RuO4 single crystals have been measured. At low temperatures, both of them were found to be positive with a linear magnetic-field dependence above a threshold field, a result not expected from electronic band theory. We argue that such behavior is a manifestation of a novel coherent state characterized by a spin pseudo gap in the quasi-particle excitation spectrum in Sr2RuO4.Comment: 4 pages + 5 figure

Cyclotron effective masses in layered metals

Many layered metals such as quasi-two-dimensional organic molecular crystals show properties consistent with a Fermi liquid description at low temperatures. The effective masses extracted from the temperature dependence of the magnetic oscillations observed in these materials are in the range, m^*_c/m_e \sim 1-7, suggesting that these systems are strongly correlated. However, the ratio m^*_c/m_e contains both the renormalization due to the electron-electron interaction and the periodic potential of the lattice. We show that for any quasi-two-dimensional band structure, the cyclotron mass is proportional to the density of states at the Fermi energy. Due to Luttinger's theorem, this result is also valid in the presence of interactions. We then evaluate m_c for several model band structures for the \beta, \kappa, and \theta families of (BEDT-TTF)_2X, where BEDT-TTF is bis-(ethylenedithia-tetrathiafulvalene) and X is an anion. We find that for \kappa-(BEDT-TTF)_2X, the cyclotron mass of the \beta-orbit, m^{*\beta}_c, is close to 2 m^{*\alpha}_c, where m^{*\alpha}_c is the effective mass of the \alpha- orbit. This result is fairly insensitive to the band structure details. For a wide range of materials we compare values of the cyclotron mass deduced from band structure calculations to values deduced from measurements of magnetic oscillations and the specific heat coefficient.Comment: 12 pages, 3 eps figure

Modelling non-dust fluids in cosmology

Currently, most of the numerical simulations of structure formation use Newtonian gravity. When modelling pressureless dark matter, or `dust', this approach gives the correct results for scales much smaller than the cosmological horizon, but for scenarios in which the fluid has pressure this is no longer the case. In this article, we present the correspondence of perturbations in Newtonian and cosmological perturbation theory, showing exact mathematical equivalence for pressureless matter, and giving the relativistic corrections for matter with pressure. As an example, we study the case of scalar field dark matter which features non-zero pressure perturbations. We discuss some problems which may arise when evolving the perturbations in this model with Newtonian numerical simulations and with CMB Boltzmann codes.Comment: 5 pages; v2: typos corrected and refs added, submitted version; v3: version to appear in JCA

A qualitative study of determinants of patient behaviour leading to an infection related hospital admission.

Objective: To describe and understand the determinants of patients' behaviours surrounding admission to hospital for an acute infective episode. Method: Patients admitted to the infection or acute medicine admission units of a major Scottish teaching hospital and commenced on antibiotic therapy after admission were included. Semi-structured face-to-face interviews were conducted using a pre-piloted interview schedule guide that focused on gathering information about patient behaviours and experiences prior to admission to hospital with an acute infection. Interviews were audio-recorded, transcribed verbatim and analysed using the Framework Approach. Emerging themes were matched to the Theoretical Domains Framework of behavioural determinants. Results: Twenty-one patients consented to participate and 18 transcripts were suitable for analysis. The most common infections were those of the skin, soft tissue and respiratory tract. From the patients' perspectives, behavioural determinants that appeared to impact their admission to hospital were principally their knowledge, beliefs of consequences, the environmental context and resources (mainly out-of-hours services), social influences and their own emotions. Determinants such as knowledge of the signs and symptoms, beliefs of consequences and environmental context were facilitators of health seeking behaviours. The main barriers were a lack of awareness of consequences of infection potentially leading to delayed admission impacting infection severity, stay in secondary care and resource utilisation. Conclusions: This study has shown that any initial patient-centred intervention that is proposed to change patient behaviour needs to be based on behavioural determinants emerging in this research. The intervention may include aspects such as patient education on resources available out-of-hours and ways to access the healthcare system, education on recognising signs of infection leading to prompter treatment and positive reinforcement for patients who present with recurrences of infection

The use of dexamethasone in women with preterm premature rupture of membranes - A multicentre, double-blind, placebocontrolled, randomised trial

No Abstract

Optical Properties of Heavy Fermion Systems with SDW Order

The dynamical conductivity $\sigma (\omega)$, reflectivity $R(\omega)$, and tunneling density of states $N(\omega)$ of strongly correlated systems (like heavy fermions) with a spin-density wave (SDW) magnetic order are studied as a function of impurity scattering rate and temperature. The theory is generalized to include strong coupling effects in the SDW order. The results are discussed in the light of optical experiments on heavy-fermion SDW materials. With some modifications the proposed theory is applicable also to heavy fermions with localized antiferromagnetic (LAF) order.Comment: 9 pages, 10 figure

Transport properties of strongly correlated metals:a dynamical mean-field approach

The temperature dependence of the transport properties of the metallic phase of a frustrated Hubbard model on the hypercubic lattice at half-filling are calculated. Dynamical mean-field theory, which maps the Hubbard model onto a single impurity Anderson model that is solved self-consistently, and becomes exact in the limit of large dimensionality, is used. As the temperature increases there is a smooth crossover from coherent Fermi liquid excitations at low temperatures to incoherent excitations at high temperatures. This crossover leads to a non-monotonic temperature dependence for the resistance, thermopower, and Hall coefficient, unlike in conventional metals. The resistance smoothly increases from a quadratic temperature dependence at low temperatures to large values which can exceed the Mott-Ioffe-Regel value, hbar a/e^2 (where "a" is a lattice constant) associated with mean-free paths less than a lattice constant. Further signatures of the thermal destruction of quasiparticle excitations are a peak in the thermopower and the absence of a Drude peak in the optical conductivity. The results presented here are relevant to a wide range of strongly correlated metals, including transition metal oxides, strontium ruthenates, and organic metals.Comment: 19 pages, 9 eps figure

Against all odds? Forming the planet of the HD196885 binary

HD196885Ab is the most "extreme" planet-in-a-binary discovered to date, whose orbit places it at the limit for orbital stability. The presence of a planet in such a highly perturbed region poses a clear challenge to planet-formation scenarios. We investigate this issue by focusing on the planet-formation stage that is arguably the most sensitive to binary perturbations: the mutual accretion of kilometre-sized planetesimals. To this effect we numerically estimate the impact velocities $dv$ amongst a population of circumprimary planetesimals. We find that most of the circumprimary disc is strongly hostile to planetesimal accretion, especially the region around 2.6AU (the planet's location) where binary perturbations induce planetesimal-shattering $dv$ of more than 1km/s. Possible solutions to the paradox of having a planet in such accretion-hostile regions are 1) that initial planetesimals were very big, at least 250km, 2) that the binary had an initial orbit at least twice the present one, and was later compacted due to early stellar encounters, 3) that planetesimals did not grow by mutual impacts but by sweeping of dust (the "snowball" growth mode identified by Xie et al., 2010b), or 4) that HD196885Ab was formed not by core-accretion but by the concurent disc instability mechanism. All of these 4 scenarios remain however highly conjectural.Comment: accepted for publication by Celestial Mechanics and Dynamical Astronomy (Special issue on EXOPLANETS