Spatial abundance and clustering of Culicoides (Diptera: Ceratopogonidae) on a local scale

BACKGROUND: Biting midges, Culicoides, of the Obsoletus group and the Pulicaris group have been involved in recent outbreaks of bluetongue virus and the former was also involved in the Schmallenberg virus outbreak in northern Europe. METHODS: For the first time, here we investigate the local abundance pattern of these two species groups in the field by intensive sampling with a grid of light traps on 16 catch nights. Neighboring trap catches can be spatially dependent on each other, hence we developed a conditional autoregressive (CAR) model framework to test a number of spatial and non-spatial covariates expected to affect Culicoides abundance. RESULTS: The distance to sheep penned in the corner of the study field significantly increased the abundance level up to 200 meters away from the sheep. Spatial clustering was found to be significant but could not be explained by any known factors, and cluster locations shifted between catch nights. No significant temporal autocorrelation was detected. CAR models for both species groups identified a significant positive impact of humidity and significant negative impacts of precipitation and wind turbulence. Temperature was also found to be significant with a peak at just below 16 degrees Celcius. Surprisingly, there was a significant positive impact of wind speed. The CAR model for the Pulicaris group also identified a significant attraction to the smaller groups of sheep placed in the field. Furthermore, a large number of spatial covariates which were incorrectly found to be significant in ordinary regression models were not significant in the CAR models. The 95% C.I. on the prediction estimates ranged from 20.4% to 304.8%, underlining the difficulties of predicting the abundance of Culicoides. CONCLUSIONS: We found that significant spatial clusters of Culicoides moved around in a dynamic pattern varying between catch nights. This conforms with the modeling but was not explained by any of the tested covariates. The mean abundance within these clusters was up to 11 times higher for the Obsoletus group and 4 times higher for the Pulicaris group compared to the rest of the field

Computational modeling with spiking neural networks

This chapter reviews recent developments in the area of spiking neural networks (SNN) and summarizes the main contributions to this research field. We give background information about the functioning of biological neurons, discuss the most important mathematical neural models along with neural encoding techniques, learning algorithms, and applications of spiking neurons. As a specific application, the functioning of the evolving spiking neural network (eSNN) classification method is presented in detail and the principles of numerous eSNN based applications are highlighted and discussed

Response of seeds and pollen of Onobrychis viciifolia and Onobrychis oxyodonta var. armena to NaCl stress

Sainfoin (Onobrychis viciifolia Scop.) is an important forage legume crop with 52 species adapted to dry and poor soils in Turkey, but little is known about the effects of salinity on germination and seedling growth in arid and semiarid regions suffering from salinity problem. The seeds and pollen of two species of sainfoin O. viciifolia and O. oxyodonta var. armena (Syn: O. armena) were exposed to 0, 5, 10, 20 and 30 dS m-1 of NaCl under in vivo and in vitro conditions and evaluated for germination under salt stress by comparing germination percentage, mean germination time, root and shoot length, fresh and dry seedling weight and dry matter. Increased salinity levels generally resulted in decrease in all traits except time to germination, dry seedling weight and dry matter, which increased at high salinity levels. O. viciifolia seeds germinated and grew more rapidly compared to O. armena seeds under NaCl stress. No decrease in germination and seedling growth up to 10 dS m-1 was recorded. On the other hand, there was a clear difference for germination and seedling growth between in vivo and in vitro conditions. Lower values were obtained from in vitro experiments; suggesting that mineral salts, sucrose and agar may have resulted in higher osmotic potential inhibiting germination and seedling growth of species compared in vivo conditions. Decrease in pollen germination with increasing salinities was very sharp, indicating that pollen germination had higher sensitive to salinity. But, pollen grains of O. armena germinated rapidly compared to O. viciifolia. The results emphasize that in vivo experiments could be used for screening of NaCl tolerance in sainfoin cultivars without expensive chemicals and sophisticated equipments, but pollen germination is more appropriate for its wild relatives

Somatic embryogenesis in white clover (Trifolium repens L.)

I White Clover (Trifolium repens L.) is an important perennial forage legume widely cultivated in Turkey and many other countries. It also helps in improving soil structure by fixing atmospheric nitrogen, and prevents soil erosion. The application of modern tissue culture techniques to this important plant should contribute to improvement in terms of production. Hypocotyls, epicotyl and cotyledon explants of a local ecotype of white clover were treated with various concentrations of Thidiazuron (TDZ) + Naphthalene acetic acid (NAA) and kinetin + NAA in MS medium to establish an efficient in vitro somatic embryogenesis system. High frequency of embryogenesis was observed on the MS medium containing 9.29 mM kinetin + 1.07 mM NAA (14.35embryos per explant) or 0.34 mM TDZ + 0.54 mM NAA (29.62 embryos per explant). It was concluded that embryogenesis was significantly influenced by the added plant growth regulators in the concentration-dependent manner;: Plantlets from the embryos were recovered on the MS medium and were transferred to a greenhouse, where they flowered and set fertile seeds

Abiotic factors affecting in vitro pollen grain germination in sainfoin (Onobrychis viciifolia Scop.)

A reliable in vitro method for germination of sainfoin pollen grains has been developed. Highest pollen germination rate of 96% with mean pollen tube length of 223.5 mum was obtained on medium containing of 100 g/l sucrose, 200 mg/l KNO3, 150 mg/l H3BO3, 150 mg/l MgSO4, 150 mg/l Ca(NO3)(2), 175 g/l PEG 4000 and stigma extract at pH 6.5

Formulation du contact avec adhérence en élasticité non linéaire entre deux solides déformables

International audienceWithin the framework of finite deformations and using an approach to the kinematics of contact due to A. Curnier, Q.C. He and J.J. Téléga, we propose a spatial thermodynamic formulation for the problem coupling unilateral condition, friction and adhesion. The adhesion is characterized by its intensity introduced by M. Frémond. In the case of frictionless contact between an hyperelastic body and a plane rigid support, with a particular `static' law for the evolution of the intensity of adhesion, the problem can be reduced to a minimization one for which we can show the existence of a solution.Dans le cadre de la mécanique non linéaire, grâce à la cinématique du contact introduite par A. Curnier, Q.C. He et J.J. Téléga, nous proposons une formulation thermodynamique eulérienne, conduisant à un problème aux limites couplant le contact unilatéral, le frottement et l'adhérence entre deux solides hyperélastiques, l'adhérence étant décrite par une variable d'état interne introduite par M. Frémond. Dans le cas particulier du contact sans frottement entre un solide hyperélastique et un support rigide plan on établit un résultat d'existence pour le problème de minimum associé, quand l'évolution de l'intensité d'adhérence est donnée par une loi “statique”

On the existence of a second Jπ = 0+ resonance at high excitation energy in 24Mg and a possible mechanism for the occurrence of resonances in the (12C + 12C) system

Evidence for the existence of a second Jπ = 0 + resonance at high excitation energy in 24Mg (E x = 19.70 MeV) is shown from a study of the 12C( 12C, α)20Ne reaction at Ec.m. = 5.80 ± 0.05 MeV. Using this result and those obtained previously, a comparison is made with the resonances observed in the second well of the fission barrier of some actinides.L'existence d'une seconde résonance Jπ = 0+ à haute énergie d'excitation dans 24Mg (Ex = 19,70 MeV) est mise en évidence au cours d'une étude de la réaction 12C(12C, α)20Ne effectuée à E c.m. = 5,80 ± 0,05 MeV. Ce résultat ainsi que les résultats antérieurs nous amènent à établir une comparaison avec les résonances observées dans le second puits de la barrière de fission de certains actinides