Comparaison de plans d’échantillonnage séquentiel binomial et de type Iwao pour le dépistage du thrips de l’oignon (Thrips tabaci) [Thysanoptera : Thripidae] sur l’oignon

Des différences transitoires de densité du thrips de l'oignon (Thrips tabaci) ont été observées entre les bordures et le centre de certains champs d'oignon (Allium cepa). Les populations de thrips sont constituées d'agrégats dispersés de façon contagieuse à l'intérieur des champs d'oignon. Deux types de plans d'échantillonnage séquentiel ont été établis pour le T. tabaci sur l'oignon: plan binomial basé sur la présence d'au moins 5 thrips plant d'oignon-1 et plan de type Iwao nécessitant le décompte de tous les thrips présents. Les limites d'acceptation de ces plans ont été calculées pour des seuils économiques de 0,9 et 2,2 thrips feuille-1 Ces plans ont été validés dans des champs abritant des populations entre 0,01 et 32,33 thripsfeuille-1. Les plans de type binomial se sont avérés aussi fiables que les plans séquentiels avec des taux d'erreur ne dépassant jamais 4%, ce qui est inférieur aux niveaux théoriques choisis de 5 et 10%. De bonnes prises de décision ont été obtenues dans 90,4 et 83,6% des cas à l'aide des plans par décompte, et dans 84,8 et 82,4% des cas à l'aide des plans binomiaux pour les seuils de 0,9 et 2,2 thrips feuille-1, respectivement. Le nombre moyen d'échantillons à prélever pour prendre une décision oscille entre 10 et 14 plants d'oignon selon le plan employé. L'emploi des plans binomiaux peut entraîner des réductions de l'effort de comptage des thrips pouvant atteindre jusqu'à 62 et 88% pour les seuils de 0,9 et 2,2 thrips feuille-1, respectivement.Transient differences in onion thrips (Thrips tabaci) densities were observed between the margins and the centre of some onion (Allium cepa) fields. Onion thrips populations consist in aggregates contagiously dispersed within onion fields. Two types of sequential sampling plans were established for T. tabaci in onions: a binomial plan based on the presence of 5 thrips plant-1, and one of the Iwao type, requiring counts of aol thrips present. Acceptation boundaries for these plans were calculated for economic thresholds of 0.9 and 2.2 thrips leaf-1. Plans were validated in fields with thrips populations varying between 0.01 and 32.33 thrips leaf-1. E3 binomial sequential sampling plans were found to be as reliable as plans requiring counts of all thrips, with an error rate not exceeding 4%, a level below the theoretical error rates of 5 and 10% used in the calculations. Correct decisions were reached in 90.4 and 83.6% of the situations with plans requiring counts of all thrips, and in 84.8 and 82.4% of the situations with binomial plans for economic thresholds of 0.9 and 2.2 thrips leaf-1, respectively. The average number of samples needed to reach a decision varied between 10 and 14 plants according to the plan used. Use of binomial plans can save up to 62 and 88% of the counting effort for thresholds of 0.9 and 2.2 thrips leaf-1, respectively

Susceptibility of apples to damage by Lygocoris communis and Lygus lineolaris (Hemiptera : Miridae)

Les dommages causés par les larves et les adultes du Lygocoris communis et du Lygus lineolaris aux pommiers (cv. Mclntosh) ont été évalués au moyen de cages de mousseline placées sur des branches de pommiers. Chaque larve de L. communis placée en cage au calice a endommagé une moyenne de 2,1 pommes alors que chaque adulte placé en cage à la nouaison en a endommagé 2,0. Les dommages causés par les jeunes larves (1er, 2e et 3e stades) ont été plus importants que ceux causés par les vieilles larves (4e et 5e stades) et les adultes. Chaque adulte hivernant de L. lineolaris a détruit une moyenne de 4,5 bourgeons à fruits. Chaque adulte de L. lineolaris a endommagé une moyenne de 4,0 pommes lorsque l'attaque avait lieu du stade du pré-bouton rose à la pleine floraison.Damage to apples (cv. Mclntosh) caused by nymphs and adults of Lygocoris communis and Lygus lineolaris was evaluated by placing insects in sleeve-cages on apple-bearing branches. Each nymph of L. communis placed in the cage at petal fall damaged an average of 2.1 apples whereas each adult placed in the cage after fruit set damaged 2.0 apples. Damage by young nymphs (1st, 2nd and 3rd instars) was severe whereas damage caused by old nymphs (4th and 5th instars) and adults was light. Each over wintered adult of L. lineolaris damaged an average of 4.5 fruit clusters. Each adult damaged an average of 4.0 apples when they attacked from tight-cluster to full-bloom stage

Improved Estimates of Cosmological Perturbations

We recently derived exact solutions for the scalar, vector and tensor mode functions of a single, minimally coupled scalar plus gravity in an arbitrary homogeneous and isotropic background. These solutions are applied to obtain improved estimates for the primordial scalar and tensor power spectra of anisotropies in the cosmic microwave background.Comment: 31 pages, 4 figures, LaTeX 2epsilon, this version corrects an embarrasing mistake (in the published version) for the parameter q_C. Affected eqns are 105, 109-110, 124, 148-153 and 155-15

Respiratory, dermal, and eye irritation symptoms associated with corexit™ EC9527A/EC9500A following the Deepwater horizon oil spill: Findings from the GuLF STUDY

BACKGROUND: The large quantities of chemical oil dispersants used in the oil spill response and cleanup (OSRC) work following the Deepwater Horizon disaster provide an opportunity to study associations between dispersant exposure (Corexit™ EC9500A or EC9527A) and human health. OBJECTIVES: Our objectives were to examine associations between potential exposure to the dispersants and adverse respiratory, dermal, and eye irritation symptoms. METHODS: Using data from detailed Gulf Long-term Follow-up (GuLF) Study enrollment interviews, we determined potential exposure to either dispersant from participant-reported tasks during the OSRC work. Between 27,659 and 29,468 participants provided information on respiratory, dermal, and eye irritation health. We estimated prevalence ratios (PRs) to measure associations with symptoms reported during the OSRC work and at study enrollment, adjusting for potential confounders including airborne total hydrocarbons exposure, use of cleaning chemicals, and participant demographics. RESULTS: Potential exposure to either of the dispersants was significantly associated with all health outcomes at the time of the OSRC, with the strongest association for burning in the nose, throat, or lungs [adjusted PR (aPR) =1.61 (95% CI: 1.42, 1.82)], tightness in chest [aPR = 1.58 (95% CI: 1.37, 1.81)], and burning eyes [aPR = 1.48 (95% CI: 1.35, 1.64). Weaker, but still significant, associations were found between dispersant exposure and symptoms present at enrollment. CONCLUSIONS: Potential exposure to Corexit™ EC9527A or EC9500A was associated with a range of health symptoms at the time of the OSRC, as well as at the time of study enrollment, 1–3 y after the spill

Power Counting in the Soft-Collinear Effective Theory

We describe in some detail the derivation of a power counting formula for the soft-collinear effective theory (SCET). This formula constrains which operators are required to correctly describe the infrared at any order in the Lambda_QCD/Q expansion (lambda expansion). The result assigns a unique lambda-dimension to graphs in SCET solely from vertices, is gauge independent, and can be applied independent of the process. For processes with an OPE the lambda-dimension has a correspondence with dynamical twist.Comment: 12 pages, 1 fig, journal versio

Optimization of Nafion Polymer Electrolyte Membrane Design and Microfabrication

Nafion is a solid electrolyte polymer that can be used as a sensor membrane in microfabricated electrochemical oxygen sensors. It allows ions to be transported between the sensor electrodes and removes the need for a liquid electrolyte. Here we used a series of small square Nafion test structures, fabricated on a variety of materials using standard thin-film patterning techniques, to optimize the design and processing of Nafion membranes. Measurements showed that the choice of photoresist developer is critical. Use of diluted MF-26A developer provided the most effective and manufacturable process. The underlying material also had an influence on robustness, with silicon dioxide and platinum giving the longest membrane lifetime under simulated conditions of use. Membrane size had no clear effect on lifetime, and under optimal processing conditions there were minimal failures even under continuous mechanical agitation for up to six weeks. We also developed test electrodes covered by Nafion, and showed that they were effective at supporting electrochemical oxygen detection

Estimation of Airborne Vapor Concentrations of Oil Dispersants COREXIT™ EC9527A and EC9500A, Volatile Components Associated with the Deepwater Horizon Oil Spill Response and Clean-up Operations

The Deepwater Horizon (DWH) drilling unit explosion above the Macondo oil well on 20 April 2010 caused the release of approximately 4.9 million barrels (779 million L) of oil into the Gulf of Mexico. As part of a larger spill response and clean-up effort, approximately 1.84 million gallons (6.81 million L) of chemical dispersants COREXIT™ EC9500A and COREXIT™ EC9527A were applied to the resultant oil slicks through spraying on the water surface by plane and by vessel and through injection at the release source near the seabed. The GuLF STUDY is investigating the health effects of workers involved in the oil spill response and clean-up after the DWH explosion, and estimates of possible exposure to chemical dispersants were needed. Exposures were estimated to the volatile components of COREXIT™ EC9500A [petroleum distillates, hydrotreated light, and propylene glycol (PG)] and of COREXIT™ EC9527A [2-butoxyethanol (2-BE) and PG] using two of AIHA IHMOD2.0© mathematical modeling tools along with the dispersants' chemical and physical properties. Monte Carlo simulations were used to reflect uncertainty in input parameters with both the two-box, constant emission model and the near and mid field plume model for indoor and outdoor activities, respectively. Possible exposure scenarios considered various evaporation rates, sizes of the dispersant pool, wind speeds, and ventilation rates. For the two-box model, mean near field exposure estimates to 2-BE ranged from 0.9 to 5.7 ppm, while mean far field estimated exposures ranged from 0.3 to 3.5 ppm. Estimates of mean near field plume model exposures ranged from 0.01 to 3.7 ppm at 2.5 ft from the source, and <0.01 to 0.3 ppm at 10 ft from the source. Estimated exposures to PG were approximately 10% of the calculated 2-BE exposures and exposures to petroleum distillates about 40% higher than the 2-BE estimates. Results indicate that compared with current occupational exposure guidelines, overexposure to petroleum distillates and PG probably did not occur in our study, but under some conditions, for short periods, exposure to 2-BE may have exceeded the limits for peak exposures. These estimates were developed for use in job-exposure matrices to estimate exposures of workers having contact with dispersant vapors for the GuLF STUDY

Detecting Current Noise with a Josephson Junction in the Macroscopic Quantum Tunneling Regime

We discuss the use of a hysteretic Josephson junction to detect current fluctuations with frequencies below the plasma frequency of the junction. These adiabatic fluctuations are probed by switching measurements observing the noise-affected average rate of macroscopic quantum tunneling of the detector junction out of its zero-voltage state. In a proposed experimental scheme, frequencies of the noise are limited by an on-chip filtering circuit. The third cumulant of current fluctuations at the detector is related to an asymmetry of the switching rates.Comment: 26 pages, 10 figures. To appear in Journal of Low Temperature Physics in the proceedings of the ULTI conference organized in Lammi, Finland (2006

Mycorrhizal fungi compromise production of endophytic alkaloids, increasing plant susceptibility to an aphid herbivore

1. Symbiosis plays a critical role in plant biology. Temperate grasses often associate with several symbiotic fungi simultaneously, including Epichloë endophytes and arbuscular mycorrhizal (AM) fungi, in shoots and roots, respectively. These symbionts often modulate plant–herbivore interactions by influencing nutritional traits (i.e. AM fungi-mediated nutrient uptake) and/or the secondary chemistry (i.e. endophytic alkaloids) of their host plant. Moreover, such grasses also accumulate large amounts of silicon (Si) from the soil, which can be deposited in tissues to act as a physical anti-herbivore defence. 2. Recent evidence suggests that both endophytes and AM fungi independently facilitate Si uptake. However, the consequences of their interactions with piercing-sucking insects (i.e. aphids), or whether Si supply, endophytes, and AM fungi interact in this regard, are currently unknown. While Si deposition may be less effective against aphids than other herbivores (i.e. chewing caterpillars), Si supply can also alter plant secondary metabolite defences, which could affect sucking insects. 3. In a factorial greenhouse experiment, we evaluated whether these components, acting alone or in combination, altered (1) foliar primary chemistry, (2) Si and symbiont-chemical (endophytic alkaloids) defences, as well as (3) performance of the bird cherry-oat aphid (Rhopalosiphum padi) feeding on tall fescue (Festuca arundinacea). 4. Endophytes decreased all aphid performance parameters, including population growth and reproduction by 40%, but their impact was reversed by the presence of AM fungi, leading to a 52% increase in aphid performance compared with plants solely hosting endophytes. This improvement in performance was associated with reduced loline alkaloid levels and higher shoot nitrogen in AM-endophytic plants. Endophytes and AM fungi exhibited antagonism, with endophytes reducing AM colonization by 34% and AM presence decreasing endophyte loline alkaloids by 44%. While both fungi jointly increased Si accumulation by 39% under Si-supplied conditions, Si had no noticeable effects on aphids. Moreover, although Si supply had no identifiable effects on AM colonization, it reduced endophyte peramine alkaloids by 24%. 5. Synthesis. Our findings indicate that symbiotic fungal partnerships and silicon provision may benefit plants but could weaken anti-herbivore defences when combined. Revealing the complex interactions among diverse fungal symbionts and showcasing their effects on different anti-herbivore defences (chemical and physical) and herbivore performance for the first time