Impact of white grub (Liqyrus subtropicus (Blatchley)) infestation on sugarcane nutrition 1

The white grub (Ligyrus subtropicus (Blatchley)) is a major insect pest of Florida sugarcane (Saccharum spp.). The primary impact this insect has on the sugarcane plant is through larval feeding on plant roots and underground stems. A greenhouse study was conducted to evaluate the effect of L. subtropicus larval feeding on N, P, K, Ca, and Mg nutrition of sugarcane. Third instar L. subtropicus larvae were introduced to the soil at rates of 0, 2, 4, 6, and 8 larvae/plant. Leaf N, P, and K concentrations decreased linearly as the level of grub infestation increased. Leaf Ca and Mg concentrations were not affected by grub feeding.     

The effects of different maternal dietary iodine concentrations on Japanese quail II. Thyroid function in embryos and hatchlingsi

Embryos (day I4 of the 16.5 day incubation period) and I day old chicks of Japanese quail (Coturnix japonica) were used to study the effects of egg I on thyroid development. The maternal diets were supplemented with 0–1200 μg I/kg of purified diet. Thyroid function, of embryos and chicks (before feeding), adapted to a wide range of egg I availability.We measured body weights, thyroid weights, thyroidal ¹²⁵I uptakes, stable I concentrations in thyroid glands and triiodothyronine (T₃) and thyroxine (T₄) concentrations in the serum.With low egg I (maternal diets with <50 μg I/kg) embryonic and chick thyroid glands were hypertrophied, thyroidal I content was very low and thyroidal radioiodine uptakes were high. Serum hormone concentrations were not significantly different from those of embryos and chicks from eggs with higher I contents. Thyroid weights were lowest in young from eggs of hens on the 150 μg I/kg diet, and the other variables studied also indicated this maternal diet provided sufficient egg I for the thyroid function of embryos and hatchlings.With high egg I (maternal diets with 300–1200 μg I/kg) thyroidal radioiodine uptakes were low but thyroidal I incorporation was related to egg I content. Serum hormone concentrations were not significantly altered by high I availability except that serum T₄ concentrations differed in a comparison of the extremes (0 vs 1200 μg I/kg in the maternal diet). As expected, from the consistency of serum hormone concentrations, embryonic growth was not affected by the I content of the eggs.In agreement with earlier studies on quail hens, our results indicate that feed supplementation of 150 μg I/kg is sufficient to meet needs without requiring alterations in thyroid function to maintain serum hormone concentrations. Developing thyroid glands adapt effectively to egg I concentrations of 0.2 to 4.1 μg I/g yolk which result from maternal diets with 0–1200 μg I/kg.     

Do Policymakers Locate Prisons for Economic Development?

While public goods can provide an overall increase in welfare, ‘inferior’ public facilities produce externalities specifically impacting host locations. Heterogeneous jurisdictional attributes, however, can cause net social benefits to vary across potential host communities. Using data from a unique public works project, this paper empirically investigates whether policymakers consider heterogeneous conditions when locating prison facilities. Results indicate that policymakers follow a process that maximizes net social benefits by systematically delegating such facilities to lagging communities; thereby potentially using the public facilities for economic development. Additionally, results suggest that policymakers properly consider existing infrastructure and agglomeration economies in the siting mechanism.     

The maintenance requirement of domestic drakes

1. Mature domestic drakes of 7 genotypes, ranging in live weight from 1.1 to 5.1 kg, were each given a daily allowance of feed just below the level of recorded ad libitum intake. 2. House temperature was maintained at 26 degrees C for 16 weeks and then at 10 degrees C for a further 8 weeks. 3. Under these conditions, live weight quickly adjusted to the level of feed supplied and then remained stable. 4. Regression of metabolisable energy intake on live weight (W) yielded estimates of maintenance requirement of 583 kJ/kgW(0.75).d at 10 degrees C and 523 kJ/kgW(0.75).d at 26 degrees C.     

A High-Temperature Electrical Conduction Mechanism in the Lower Mantle Phase (Mg,Fe)1-xO

Measurements of electrical conductivity at high pressure and temperature were taken on the lower mantle phase magnesiowustite with varying Fe3+ content. Although previous measurements at atmospheric pressure suggest Fe2+-Fe3+ hopping (small polaron) as the dominant conductivity mechanism, the present experiments show a change in charge transport mechanism with temperature. The lower temperature measurements are consistent with small polaron conduction, but at higher temperatures, which are more applicable to the lower mantle, a large polaron mechanism is suggested. Because these mechanisms have different temperature and compositional dependencies, this transition has important implications for extrapolation to mantle conditions.     

Tracking the evolution of a hydrothermal event plume with a RAFOS neutrally buoyant drifter

The migration and evolution of a deep ocean hydrothermal event plume were tracked with a neutrally buoyant RAFOS float. The float remained entrained in the plume for 60 days, and the plume vorticity was calculated directly from the anticyclonic motion of the float. Concentrations of suspended particles, particulate iron, and dissolved manganese in the plume did not decay significantly during the 60 days, which indicates that event plumes would be easily detectable a year after formation.     

Comparative Earth History and Late Permian Mass Extinction

The repeated association during the late Neoproterozoic Era of large carbon-isotopic excursions, continental glaciation, and stratigraphically anomalous carbonate precipitation provides a framework for interpreting the reprise of these conditions on the Late Permian Earth. A paleoceanographic model that was developed to explain these stratigraphically linked phenomena suggests that the overturn of anoxic deep oceans during the Late Permian introduced high concentrations of carbon dioxide into surficial environments. The predicted physiological and climatic consequences for marine and terrestrial organisms are in good accord with the observed timing and selectivity of Late Permian mass extinction.