A change in the geodynamics of continental growth 3 billion years ago

Models for the growth of continental crust rely on knowing the balance between the generation of new crust and the reworking of old crust throughout Earth's history. The oxygen isotopic composition of zircons, for which uranium-lead and hafnium isotopic data provide age constraints, is a key archive of crustal reworking. We identified systematic variations in hafnium and oxygen isotopes in zircons of different ages that reveal the relative proportions of reworked crust and of new crust through time. Growth of continental crust appears to have been a continuous process, albeit at variable rates. A marked decrease in the rate of crustal growth at ~3 billion years ago may be linked to the onset of subduction-driven plate tectonics.     

Comparison of the performance of dairy cows offered kale,swedes and perennial ryegrass herbage in situ and perennial ryegrass silage fed indoors in late pregnancy during winter in Ireland

The effects on the performance of dairy cows offered kale, swedes, and perennial ryegrass in situ and perennial ryegrass silage fed indoors to dairy cows pre‐partum during winter in Ireland was examined. Eighty‐eight spring‐calving dairy cows were randomly assigned to one of four offered treatments; (i) 8 kg of dry matter (DM) of kale leaf and stem + 4 kg DM of perennial ryegrass silage (treatment K), (ii) 8 kg DM of the root and leaf of swedes + 4 kg DM of perennial ryegrass silage (treatment S), (iii) 12 kg DM of perennial ryegrass herbage (treatment G) offered in situ and (iv) perennial ryegrass silage offered ad libitum indoors (treatment ID). Cows on treatments K, S and ID had a greater (P < 0·001) increase in body condition score (0·20, 0·14 and 0·50 units respectively) pre‐partum than cows on treatment G which lost 0·22 units. Pre‐partum treatment had no effect on variables of milk production in the following lactation. In the first 100 d of lactation, cows on treatment G pre‐partum had a lower milk fat concentration (35·6 g kg^?1) compared with cows on treatments S and ID (38·3 and 39·3 g kg^?1 respectively). There was no effect of treatment on the intervals between parturition and first insemination (mean 74·6 d) and conception (mean 96·1 d). The results suggest that offering kale and swedes to dairy cows pre‐partum resulted in a similar lactation performance to dairy cows grazing a perennial ryegrass sward or offered perennial ryegrass silage indoors.     

Role of the waxy skin layer in moisture loss during dehydration of prunes

Permeability studies of water through the skin and flesh of d'Agen plums have been carried out by radiotracer and PGSE NMR techniques as a function of moisture content. The results have shown that the diffusion coefficient of water through the skin layer increases as the fruit is dried at 70 degrees C or above. By contrast, the water diffusion through the fruit becomes more hindered as moisture is lost and structural collapse of the cell layers takes place. Values for diffusion coefficients of water at 21 degrees C through the fruit of 1 x 10(-)(9) m(2) s(-)(1) for fresh plums and 2.0 x 10(-)(10) m(2) s(-)(1) for fruit dried to 50% moisture content (wet basis) were found. Structural studies using scanning electron microscopy techniques were also performed. These showed that drying induces marked changes to the waxy skin layer of the fruit as well as the fruit flesh. These results are discussed in terms of the important role that the plum skin has in modulating the moisture loss process during dehydration, particularly at early stages of drying.     

Geomorphic features and soil formation of arid lands in Northeastern Jordan

Arid and semiarid lands occupy about one-third of the Earth's land surface. Interpretation of soil formation and geomorphic features of arid lands is needed to assess their soil ecological potentials, limitations, problems and management needs. The objective of this paper was to study the geomorphic features and soil formation of the arid lands in northeastern Jordan, to provide information that could be used by land managers in the study area and other arid land areas. Five representative soil pedons were excavated and described in the field. Soil samples from each horizon per pedon were taken to the laboratory for chemical and physical analyses. Geomorphic features of the area were also studied. Most of studied land surfaces are plains where eolian deflation has exposed loose gravels consisting predominantly of pebbles forming desert pavements. Desert pavements cover most of the land surface, excluding the mud playas, and are composed of basalt clasts. The accumulation of calcium carbonate and gypsum within these soils create problems for their agricultural development. Accumulation of eolian fine-grained silt has resulted in the formation of a vesicular horizon. The climatic variations during the late quaternary and the late Holocene periods contributed to the development of the desert pavement and the vesicular horizons. Clay illuviation and argillic horizon development within these soils is assumed to be a relict feature from more humid climates during the Quaternary. Sustainable agricultural development of such arid lands may not be easy. In general, these soils have high erodibility, high runoff generation potential, high susceptibility to seal and crust formation, poor water-holding capacity, pedon hardening and structural instability.     

Moh’s micrographic surgery for the management of a periocular mast cell tumor in a dog

A 3‐year‐old neutered male boxer dog presented with a 6‐month history of a waxing and waning mass of the left dorsotemporal eyelid margin. Cytology and biopsy confirmed a diagnosis of mast cell neoplasia. Systemic staging of the dog failed to reveal any evidence of metastatic neoplasia. Owing to the location of the tumor within the eyelid margin and the wide surgical margins recommended for excision of mast cell tumors, Mohs micrographic surgery (MMS) was chosen for its potential to conserve tissues while providing intraoperative confirmation the tumor was completely excised. Utilizing MMS horizontal sectioning technique, 100% of the surgical margins were assessed prior to closure of the surgical wound. This represents the first time a comprehensive MMS protocol was used in a veterinary patient under general anesthesia.     

The peri‐urban Pacific: From exclusive to inclusive cities

Abstract: As the Pacific Islands continue to urbanise, existing models of governance and planning are coming under greater pressure and scrutiny. Both the city council approach and the ‘good’ urban governance agenda of donors have weaknesses in the region, especially in dealing with peri‐urban settlements where the most rapid urban population growth is occurring. This is resulting in increased social discontent and conflict. This paper critiques the ways in which Pacific Island towns and cities are governed and calls for an approach which is more inclusive (and less hierarchical) and informed by concepts of citizenship and social justice. Indeed, policy makers will need to broaden their concepts and practices of governance if many Pacific cities are to be socially, politically, and envir‐onmentally sustainable. However, the political‐economy of urban development in the region is not proving conducive to consensus, with conflict a more likely outcome in the foreseeable future.     

Pistillate papaya flower: a morphological anomaly

The pistillate flower of Carica papaya is a pleurogynous unisexual form derived intraspecifically from a perigynous bisexual ancestor. It is a morphological anomaly in that the ovary consists of two cycles of carpels which, in the ancestor, arise on the receptacle at different levels as dissimilar orders of organs. The bulk of the pentamerous ovary and the dorsal carpellary vascular system are derived from a cycle of five stamens in the ancestor. The ventral carpellary system is inherited intact from the ancestor which has normal morphology in the sense that the carpels consist of a single cycle of sporophylls.     

Acute exposure to copper induces variable intensity of oxidative stress in goldfish tissues

Copper is an essential element, but at high concentrations, it is toxic for living organisms. The present study investigated the responses of goldfish, Carassius auratus, to 96 h exposure to 30, 300, or 700 μg L^?1 of copper II chloride (Cu²⁺). The content of protein carbonyls was higher in kidney (by 158%) after exposure to 700 mg L^?1 copper, whereas in gills, liver, and brain, we observed lower content of protein carbonyls after exposure to copper compared with control values. Exposure to copper resulted in increased levels of lipid peroxides in gills (76%) and liver (95–110%) after exposure to 300 and 700 μg L^?1 Cu²⁺. Low molecular mass thiols were depleted by 23–40% in liver and by 29–67% in kidney in response to copper treatment and can be used as biomarkers toxicity of copper. The activities of primary antioxidant enzymes, superoxide dismutase and catalase, were increased in liver as a result of Cu²⁺ exposure, whereas in kidney catalase activity was decreased. The activities of glutathione-related enzymes, glutathione peroxidase, glutathione-S-transferase, and glutathione reductase were decreased as a result of copper exposure, but glutathione reductase activity increased by 25–40% in liver. Taken together, these data show that exposure of fish to Cu²⁺ ions results in the development of low/high intensity oxidative stress reflected in enhanced activities of antioxidant and associated enzymes in different goldfish tissues.