Radar detection of the nucleus and coma of comet hyakutake

Radar observations of comet Hyakutake (C/1996 B2) made at the Goldstone Deep Space Communications Complex in California have detected echoes from the nucleus and from large grains in the inner coma. The nucleus of this bright comet was estimated to be only 2 to 3 kilometers in diameter. Models of the coma echo indicate backscatter from porous, centimeter-size grains ejected anisotropically at velocities of tens of meters per second. The radar observations suggest that a comet's activity may be a poor indicator of its size and provide evidence that large grains constitute an important component of the mass loss from a typical active comet.     

HD 181068: a red giant in a triply eclipsing compact hierarchical triple system

Hierarchical triple systems comprise a close binary and a more distant component. They are important for testing theories of star formation and of stellar evolution in the presence of nearby companions. We obtained 218 days of Kepler photometry of HD 181068 (magnitude of 7.1), supplemented by ground-based spectroscopy and interferometry, which show it to be a hierarchical triple with two types of mutual eclipses. The primary is a red giant that is in a 45-day orbit with a pair of red dwarfs in a close 0.9-day orbit. The red giant shows evidence for tidally induced oscillations that are driven by the orbital motion of the close pair. HD 181068 is an ideal target for studies of dynamical evolution and testing tidal friction theories in hierarchical triple systems.     

The Landfill of TBT Contaminated Harbour Sludge on Rinsing Fields—a Hazard for the Soil Fauna? Risk Assessment with Earthworms

Despite the cutback of the use of antifouling paints containing tributyltin (TBT), harbour sediments are still “hot spots” for organotin pollution, which is one of the most toxic substances for aquatic organisms. Harbours have to be freed constantly of suspended sediments, to guarantee unhindered shipping. The deposition of these TBT contaminated sediments on rinsing fields is supposed to comprise a minimisation of the risk potential for humans and environment. To investigate if TBT contaminated sediment might present a hazard to the existing soil fauna, a risk assessment with earthworms was performed. The original TBT contaminated sediment induced 94% mortality, compared to 2% in the uncontaminated standard Lufa soil. It was assumed that the high salinity (23 dS/m) was the reason for the mortality rather than the TBT concentration of 600 μg/kg soil (dry weight). To reduce the soil salinity, the TBT substrate was first washed with deionised water and then mixed with the uncontaminated artificial OECD soil (=TBT_mix), which resulted, however, in a lower TBT concentration (132 μg/kg soil dw.). The uncontaminated OECD reference soil resulted in high earthworm mortality (34%). Despite the reduced salinity (10 dS/m) and lower TBT concentration, the TBT_mix substrate induced high mortality rates (42%), reduced reproduction (17% compared to the control) and resulted in a significant substrate avoidance of 92%. Consequently, the landfilling of the TBT contaminated harbour sludge might (i) present a hazard to the existing soil fauna at the rinsing fields due to high salinity and the TBT contamination, and (ii) a quick recolonisation of the contaminated substrate by earthworms can not be expected.     

Water-dispersible clay after wetting and drying cycles in four Brazilian oxisols

Widespread intensive land use in the seasonal tropics can damage the physical stability of aggregates. Similar damage can be expected from wetting and drying cycles causing aggregate fragmentation and, consequently, leading to an increase in their specific area and exposure of internal electric charges. Thus, we hypothetised that the influence of wetting and drying cycles is dependent on the mineralogical composition of oxisols (latosols) and it is higher in soils with low aggregate stability. A greenhouse experiment was carried out to test this hypothesis in highly weathered soils from Brazil, all with variable-charge clays and highly stable aggregates. Wetting and drying cycles were defined from the quantity of water available between field capacity and the permanent wilting point. Soil columns were submitted to 0, 2, 6, 9, 12, 15 and 18 wetting and drying cycles. After each number of wetting and drying defined physical and chemical properties were determined. Statistical analysis, such as simple and multiple linear regression and Pearson's correlation were performed, showing significantly correlated WDC contents with wetting and drying cycles. The obtained results led to the conclusion that there was a close interdependence among mineralogical composition, aggregate stability and WDC influenced by wetting and drying cycles. Soils of reduced aggregate stability like kaolinitcs made them more susceptible to the action of wetting and drying on the WDC. Changes in the WDC with wetting and drying cycles showed correlated with eletrochemical properties.     

Habitat selection by the pale-headed brush-finch (Atlapetes pallidiceps) in southern Ecuador: implications for conservation

The pale-headed brush-finch (Atlapetes pallidiceps) is threatened with extinction due to habitat loss, but very little is known about its ecological requirements. We used multiple logistic regression to study habitat selection of this species at landscape, territory, and nest site scales in order to make recommendations about effective management. Habitat selection by the sympatric stripe-headed brush-finch (Buarremon torquatus) was examined with the same methods in order to analyse interspecific resource partitioning and potential competition. The pale-headed brush-finch selected semi-open habitat types with intermediate scrub heights, and avoided forests. Nest sites depended on the presence of vines or bamboo. By contrast, the stripe-headed brush-finch chose dense habitat with low ground cover under tall vegetation and avoided semi-open habitat. The two species had overlapping territories but differed significantly in microhabitat use and the use of vegetation strata. We found no convincing evidence that the stripe-headed brush-finch displaces the pale-headed brush-finch from optimal habitat. The preservation of semi-open scrubland maintained by low-intensity grazing is suggested for future conservation of the pale-headed brush-finch.     

Effect of water and feed withdrawal and health status on blood and serum components, body weight loss, and meat and carcass characteristics of Holstein slaughter cows

During marketing, cattle may be exposed to periods of water deprivation. The impact of water and feed access and health status on the physiological well-being and carcass characteristics of Holstein slaughter cows during preslaughter marketing was studied through analysis of serum components, BW loss percentage, and fresh meat composition. Ninety-one multiparous Holstein cows (609 ± 89 kg mean BW, 2.9 ± 0.5 mean BCS, varying stage of lactation) were purchased over 3 wk in 3 groups (n = 31, 29, and 31) at a terminal market in central Wisconsin. Each cow was screened to determine health status (sick or not sick) and randomly assigned to 1 of 3 water and feed withdrawal treatment pens (AL, ad libitum access to water for 36 h; 18H, 18 h of ad libitum access to water followed by 18 h of water withdrawal; 36H, 36 h of water withdrawal; all 3 treatments included 36 h of feed withdrawal) in a randomized complete block arrangement with repeated measures for serum components. Blood samples were collected by tail venipuncture at 0, 9, 18, 27, and 36 h of each treatment. Ambient temperatures were 1.9 ± 6.2°C during the trial period, which occurred over a 3-wk period in March and April 2007 near Arlington, WI. No difference (P > 0.05) was observed in mean serum cortisol in AL (18.41 ± 2.17 ng/mL) or 36H (22.98 ± 2.17 ng/mL). Mean serum glucose was greater (P < 0.05) in 36H pens (78.15 ± 0.77 mg/dL) than AL (75.91 ± 0.77 mg/dL). Mean serum creatinine was greater (P < 0.05) in 36H pens (0.71 ± 0.03 mg/dL) than AL (0.60 ± 0.03 mg/dL). The 36H pens also displayed increased (P < 0.05) serum albumin, anion gap, Ca, Cl, Na, cholesterol, and aspartate aminotransferase over AL. Greater (P < 0.05) mean percentage BW loss was observed in 36H pens (5.2 ± 0.6%) than AL (3.1 ± 0.6%). Mean muscle protein (%) was greater (P < 0.05) in 36H (22.2 ± 0.4%) than 18H (21.3 ± 0.4%). Mean muscle moisture (%) was greater (P < 0.05) in AL and 18H (75.3 ± 0.4% and 75.2 ± 0.4%) than 36H. Mean 24-h pH values were 5.92 (AL), 5.92 (18H), and 5.81 (36H; SE = 0.04) and were not different (P < 0.05). Observed pH and color values indicated a borderline dark-cutter state across all cattle in the study, regardless of water and feed access treatment. Based on these results, water and feed withdrawal in lairage should not exceed 18 h during the marketing of Holstein slaughter cows acclimated to springtime conditions to maintain BW, serum component concentrations, and fresh meat composition.     

Investigations into the toxicity of Echium plantagineum in sheep: 1. Field grazing experiments

A field grazing trial was undertaken to monitor the health and production of crossbred sheep grazing pasture where Echium plantagineum constituted a considerable proportion of the available forage. The trial, conducted for 19 months over successive grazing seasons, demonstrated a significant difference in production, with sheep on the E. plantagineum pasture being lighter and growing less wool compared with sheep on Echium-free pasture. No mortalities involving pyrrolizidine alkaloid poisoning were recorded in sheep grazing E. plantagineum, although there was histological evidence of moderately severe liver damage associated with high liver copper concentrations in at least one sheep following the grazing of large quantities of the plant.