Use of Ethanol-and-Turpentine-Baited Flight Traps to Monitor \u3ci\u3ePissodes\u3c/i\u3e Weevils (Coleoptera: Curculionidae) in Christmas Tree Plantations

Pissodes nemorensis and Pissodes strobi are major pests of pine production in eastern North America. Ethanol-and-turpentine baited traps were used here to monitor weevil populations in a Scotch pine Christmas tree plantation in Wisconsin. Baited pitfall traps were ineffective in trapping either weevil species. However, baited flight traps at 0.8 and 1.6 m above ground effectively captured flying weevils of both species, 70% of which were P. nemoren­sis. Females of both species were more attracted than males to the ethanoll turpentine baits. Significantly more female P. nemorensis and total P. nemorensis were trapped at a height of 0.8 m than 1.6 m. There was no significant difference in male P. nemorensis response to the different heights, nor was there a significant difference in response to trap height by P. strobi

Initial phases of massive star formation in high infrared extinction clouds. II. Infall and onset of star formation

The onset of massive star formation is not well understood because of observational and theoretical difficulties. To find the dense and cold clumps where massive star formation can take place, we compiled a sample of high infrared extinction clouds, which were observed previously by us in the 1.2 mm continuum emission and ammonia. We try to understand the star-formation stages of the clumps in these high extinction clouds by studying the infall and outflow properties, the presence of a young stellar object (YSO), and the level of the CO depletion through a molecular line survey with the IRAM 30m and APEX 12m telescopes. Moreover, we want to know if the cloud morphology, quantified through the column density contrast between the clump and the clouds, has an impact on the star formation occurring inside it. We find that the HCO+(1-0) line is the most sensitive for detecting infalling motions. SiO, an outflow tracer, was mostly detected toward sources with infall, indicating that infall is accompanied by collimated outflows. The presence of YSOs within a clump depends mostly on its column density; no signs of YSOs were found below 4E22 cm-2. Star formation is on the verge of beginning in clouds that have a low column density contrast; infall is not yet present in the majority of the clumps. The first signs of ongoing star formation are broadly observed in clouds where the column density contrast between the clump and the cloud is higher than two; most clumps show infall and outflow. Finally, the most evolved clumps are in clouds that have a column density contrast higher than three; almost all clumps have a YSO, and in many clumps, the infall has already halted. Hence, the cloud morphology, based on the column density contrast between the cloud and the clumps, seems to have a direct connection with the evolutionary stage of the objects forming inside

Transition from Ekman flow to Taylor vortex flow in superfluid helium

By numerically computing the steady axisymmetric flow of helium II confined inside a finite aspect ratio Couette annulus, we determine the transition from Ekman flow to Taylor vortex flow as a function of temperature and aspect ratio.We find that the low-Reynolds number flow is quite different to that of a classical fluid, particularly at lower temperatures.At high aspect ratio our results confirm the existing linear stability theory of the onset of Taylor vortices, which assumes infinitely long cylinders.Comment: 12 pages, 8 figures; submitte

Pattern reconstruction and sequence processing in feed-forward layered neural networks near saturation

The dynamics and the stationary states for the competition between pattern reconstruction and asymmetric sequence processing are studied here in an exactly solvable feed-forward layered neural network model of binary units and patterns near saturation. Earlier work by Coolen and Sherrington on a parallel dynamics far from saturation is extended here to account for finite stochastic noise due to a Hebbian and a sequential learning rule. Phase diagrams are obtained with stationary states and quasi-periodic non-stationary solutions. The relevant dependence of these diagrams and of the quasi-periodic solutions on the stochastic noise and on initial inputs for the overlaps is explicitly discussed.Comment: 9 pages, 7 figure