Volcanism on Mercury: evidence from the first MESSENGER flyby     

Head JW  Murchie SL  Prockter LM  Robinson MS  Solomon SC  Strom RG  Chapman CR  Watters TR  McClintock WE  Blewett DT  Gillis-Davis JJ 《Science (New York, N.Y.)》2008,321(5885):69-72

The origin of plains on Mercury, whether by volcanic flooding or impact ejecta ponding, has been controversial since the Mariner 10 flybys (1974-75). High-resolution images (down to 150 meters per pixel) obtained during the first MESSENGER flyby show evidence for volcanic vents around the Caloris basin inner margin and demonstrate that plains were emplaced sequentially inside and adjacent to numerous large impact craters, to thicknesses in excess of several kilometers. Radial graben and a floor-fractured crater may indicate intrusive activity. These observations, coupled with additional evidence from color images and impact crater size-frequency distributions, support a volcanic origin for several regions of plains and substantiate the important role of volcanism in the geological history of Mercury.  相似文献   

Galactic evolution: a survey of recent progress     

Strom KM  Strom SE 《Science (New York, N.Y.)》1982,216(4546):571-580

Current observational knowledge bearing on the evolution of elliptical and disk galaxies is reviewed. Particular emphasis is placed on identifying the factors that appear common to all galaxies of a particular type as opposed to those that seem to depend on environmental conditions. The success of various classes of galactic formation and evolution models used to confront these data is evaluated.  相似文献   

Venus: atmospheric motion and structure from mariner 10 pictures     

Murray BC  Belton MJ  Danielson GE  Davies ME  Gault D  Hapke B  O'leary B  Strom RG  Suomi V  Trask N 《Science (New York, N.Y.)》1974,183(4131):1307-1315

The Mariner 10 television camieras imaged the planet Venus in the visible and near ultraviolet for a period of 8 days at resolutions ranging from 100 meters to 130 kilometers. Tle general pattern of the atmospheric circulation in the upper tropospheric/lower stratospheric region is displayed in the pictures. Atmospheric flow is symmetrical between north and south hemispheres. The equatorial motions are zonal (east-west) at approxiimnately 100 meters per second, consistent with the previously inferred 4-day retrograde rotation. Angular velocity increases with latitude. The subsolar region, and the region downwind from it, show evidence of large-scale convection that persists in spite of the main zonal motion. Dynamical interaction between the zonal motion and the relatively stationary region of convection is evidenced by bowlike waves.  相似文献   

Dietary Fat Supplementation and the Consequences for Oocyte and Embryo Quality: Hype or Significant Benefit for Dairy Cow Reproduction?     

JLMR Leroy  RG Sturmey  V Van Hoeck  J De Bie  PJ McKeegan  PEJ Bols 《Reproduction in domestic animals》2014,49(3):353-361

In many countries, fat supplementation in the diet has become common in the dairy industry. There are several ideas as to how dietary fat could influence reproductive performance. Saturated fatty acids, such as palm oil, can increase milk yield but may aggravate negative energy balance and thus may impair fertility when fed during the first week post‐partum. However, priming the lipid oxidation in the liver by feeding saturated fats during the dry period has recently been shown to be a potentially promising strategy to mitigate fat mobilization and liver accumulation post‐partum. Furthermore, polyunsaturated fats (omega‐3 fatty acids and conjugated linoleic acids) are fed to reduce the ‘de novo’ fat synthesis in the udder and thus the milk fat content, which may be of modest benefit for overall energy balance. Furthermore, omega‐6 and omega‐3 polyunsaturated fatty acids are reported to alter follicular growth, steroid synthesis and prostaglandin metabolism in the ovary and endometrium, respectively. Omega‐6 fatty acids are believed to have pro‐inflammatory and thus PGF2α‐stimulating properties rendering them extra value as ‘nutraceutical’ early post‐partum, while omega‐3 fatty acids can weaken this inflammatory potency, leading to a higher chance of survival of the embryo when supplemented during the periconceptual period. Unfortunately, research results rarely provide a consensus in this perspective. The consequences of these fat‐feeding strategies on oocyte and embryo quality remain an intriguing issue for debate. Fat feeding may alter the microenvironment of the growing and maturing oocyte of the early and older embryo and thus may affect reproductive outcome. We recently reported that dietary‐induced hyperlipidaemic conditions can be harmful for embryo development and metabolism. However, to date, research results remain somewhat conflicting most probably due to differences in fat sources used, in diet and duration of supplementation and in experimental set‐up in general.  相似文献   

Chemical immobilisation and satellite tagging of free‐living southern cassowaries     

HA Campbell  RG Dwyer  S Sullivan  D Mead  G Lauridsen 《Australian veterinary journal》2014,92(7):240-245

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Pesticides in Yard Waste Compost     

Peter F. Strom 《Compost science & utilization》2013,21(1):54-60

Samples from six yard waste composting facilities in New Jersey were analyzed for a wide range of pesticide residues. Chlordane was found at low levels (0.3-3.2 mg/kg) in all samples; no other pesticide was detected. It appears likely that the source of the chlordane is the residential soil incorporated with the raw yard waste during collection. Based on these findings, routine analysis of yard waste compost for pesticide residues does not appear warranted.  相似文献   

Pelvic Parameters, Growth Rate, Puberty, and their Interrelationships in Young Dairy Heifers     

AG Ramin  RCW Daniel  DC Fenwick  RG Verrall 《Reproduction in domestic animals》1995,30(3):117-123

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Polyarthritis in wild mice (Mus musculus) caused by Streptobacillus moniliformis     

JD TAYLOR  CP STEPHENS  RG DUNCAN†  GR SINGLETON† 《Australian veterinary journal》1994,71(5):143-145

SUMMARY Mice trapped on farms in south-eastern Queensland had chronic abscessating osteoarthritides mainly involving the carpi and tarsi. Pleomorphic bacteria were shown by silver staining to be plentiful within lesions. Streptobacillus moniliformis was isolated from the joints, and streptobacillary polyarthritis was diagnosed. Other lesions observed included subcutaneous and hepatic abscesses.  相似文献   

Detecting benzimidazole resistance with faecal egg count reduction tests and in vitro assays   总被引：2，自引：0，他引：2  

PJ MARTIN  N ANDERSON  RG JARRETT† 《Australian veterinary journal》1989,66(8):236-240

Composite strains of Trichostrongylus colubriformis and Ostertagia spp consisting of 0, 1, 10, 25, 50, 75, 90, and 100% of known resistant strains were prepared and tested for benzimidazole resistance using faecal egg count reduction tests, in vitro egg hatch assays and tubulin binding assays. All tests detected resistance where the proportion of the resistant strain in the composite was 50% or more, whereas none of the tests unequivocally detected resistance below 25%. Egg count reduction tests were no less sensitive than the in vitro tests in detecting low levels of resistance but the egg hatch and tubulin binding assays provided a better quantitative estimate of moderate to high levels of resistance. Faecal egg count reduction therefore, provides a suitable means of detecting resistance in the field but tests, more sensitive to low levels of resistance are required. Results indicate that the use of post-treatment counts alone provides an adequate indication of anthelmintic efficiency.  相似文献   

Ultrasonographic characteristics of soft tissue tumours in dogs   总被引：1，自引：1，他引：0  

ZHK Loh  GS Allan  RG Nicoll  GB Hunt 《Australian veterinary journal》2009,87(8):323-329

Objective   To identify and describe the ultrasonographic features of soft tissue tumours in dogs.
Procedure   Superficial soft tissue tumours of various histological types, including mast cell tumours (MCTs) and soft tissue sarcomas (STSs), were evaluated. Ultrasound was used to visualise internal characteristics of the tumour, including vascularity. Tumours were categorised according to size, shape, margin definition, tissue plane mobility, echogenicity, echotexture, acoustic shadowing or enhancement and vessel distribution. Objective measurements of intratumoural blood flow included velocities and maximal perfused cross-sectional area (fractional area). Logistic regression models incorporating a variety of data were used in an attempt to predict the histopathological type of tumours.
Results   The logistic regression model defined by the parameters echotexture, margin definition and presence of subcapsular vessels was highly predictive of MCTs (> 73%; P = 0.024). Several other trends, including a larger size for STSs and less vascularity for both MCTs and STSs, were observed, but did not reach statistical significance.
Conclusion   This preliminary study has shown the potential diagnostic value of ultrasound in differentiating soft tissue tumours. However, at present, ultrasound cannot replace biopsy and histopathological evaluation for tumour diagnosis.  相似文献