Development of a Survey Technique for Larvae of the Grass Webworm and Other Lepidopterous Species in Turfgrass

Sampling techniques for larvae of the grass webworm, Herpetogramma licarsisalis (Walker) (Lepidoptera: Pyralidae) in turfgrass were studied. Sprinkling 1 liter of a 0.0015% aqueous solution of pyrethrins or 0.25% detergent into a 1,860-cm2 frame forced 61 and 55% of the larvae to the surface, respectively, compared with 4 liters of each irritant. The need for a greater volume of water than the commonly used technique of applying 4 liters/0.84 m2 was apparent. Continuous observation was required during the 10 min after application of either irritant to assure an accurate count, since 29% of the surfaced larvae reentered the thatch within 5 min and 38 to 39% reentered within 10 min. The detergent forced >50% of the larve to surface within 2 min. compared with 4 min with pyrethrins. Liquid irritants surfaced ca. 3 times more larvae in 5 to 10 min than plywood set out overnight. Similar responses to the presence of minor populations of the lawn armyworm, the black cutworm, and the fiery skipper indicate that other turf-infesting lepidopterous larvae may be sampled with the same technique

Population status and diet of the Yellow-legged Gull in the Azores.

During 2004 a census of the Yellow-legged Gull (Larus michahellis atlantis) was conducted in the Azores to assess its present status in the archipelago. The census yielded an estimate of 4249 breeding pairs, an increase by almost 60% since the previous survey conducted in 1984. Gulls were detected on a total of 14 islets and/or sea stacks and are probably limiting the distribution of terns in the archipelago. Out of 37 gull breeding sites found during the 1984 and 2004 surveys, 24 were located within 1 km of tern colonies. All the gull colonies were coastal except Lagoa do Fogo on São Miguel Island. Pellet analysis indicated that gulls from all the colonies feed on refuse, but the percentage of pellets containing refuse on islands with small human populations was less than half than that of islands with more than 55000 inhabitants. Gulls have no direct competitors in the Azores and benefit from an increase in refuse production. The growing number and size of rubbish dumps over the last two decades has probably contributed to the large increase in the Azorean population

Applications of control theory

Applications of control theory are considered in the areas of decoupling and wake steering control of submersibles, a method of electrohydraulic conversion with no moving parts, and socio-economic system modelling

Manufactured caverns in carbonate rock

Disclosed is a process for manufacturing underground caverns suitable in one embodiment for storage of large volumes of gaseous or liquid materials. The method is an acid dissolution process that can be utilized to form caverns in carbonate rock formations. The caverns can be used to store large quantities of materials near transportation facilities or destination markets. The caverns can be used for storage of materials including fossil fuels, such as natural gas, refined products formed from fossil fuels, or waste materials, such as hazardous waste materials. The caverns can also be utilized for applications involving human access such as recreation or research. The method can also be utilized to form calcium chloride as a by-product of the cavern formation process

Amplitude dependent frequency, desynchronization, and stabilization in noisy metapopulation dynamics

The enigmatic stability of population oscillations within ecological systems is analyzed. The underlying mechanism is presented in the framework of two interacting species free to migrate between two spatial patches. It is shown that that the combined effects of migration and noise cannot account for the stabilization. The missing ingredient is the dependence of the oscillations' frequency upon their amplitude; with that, noise-induced differences between patches are amplified due to the frequency gradient. Migration among desynchronized regions then stabilizes a "soft" limit cycle in the vicinity of the homogenous manifold. A simple model of diffusively coupled oscillators allows the derivation of quantitative results, like the functional dependence of the desynchronization upon diffusion strength and frequency differences. The oscillations' amplitude is shown to be (almost) noise independent. The results are compared with a numerical integration of the marginally stable Lotka-Volterra equations. An unstable system is extinction-prone for small noise, but stabilizes at larger noise intensity

Cannibalism as a life boat mechanism

Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one

Small drill-hole, gas mini-permeameter probe

The distal end of a basic tube element including a stopper device with an expandable plug is positioned in a pre-drilled hole in a rock face. Rotating a force control wheel threaded on the tube element exerts force on a sleeve that in turn causes the plug component of the stopper means to expand and seal the distal end of the tube in the hole. Gas under known pressure is introduced through the tube element. A thin capillary tube positioned in the tube element connects the distal end of the tube element to means to detect and display pressure changes and data that allow the permeability of the rock to be determined

The Molonglo Reference Catalog 1-Jy radio source survey IV. Optical spectroscopy of a complete quasar sample

Optical spectroscopic data are presented here for quasars from the Molonglo Quasar Sample (MQS), which forms part of a complete survey of 1-Jy radio sources from the Molonglo Reference Catalogue. The combination of low-frequency selection and complete identifications means that the MQS is relatively free from the orientation biases which affect most other quasar samples. To date, the sample includes 105 quasars and 6 BL Lac objects, 106 of which have now been confirmed spectroscopically. This paper presents a homogenous set of low-resolution optical spectra for 79 MQS quasars, the majority of which have been obtained at the Anglo-Australian Telescope. Full observational details are given and redshifts, continuum and emission-line data tabulated for all confirmed quasars.Comment: 40 pages, ApJS in pres