Infrared observations of the neptunian system     

Conrath B  Flasar FM  Hanel R  Kunde V  Maguire W  Pearl J  Pirraglia J  Samuelson R  Gierasch P  Weir A  Bezard B  Gautier D  Cruikshank D  Horn L  Springer R  Shaffer W 《Science (New York, N.Y.)》1989,246(4936):1454-1459

The infrared interferometer spectrometer on Voyager 2 obtained thermal emission spectra of Neptune with a spectral resolution of 4.3 cm(-1). Measurements of reflected solar radiation were also obtained with a broadband radiometer sensitive in the visible and near infrared. Analysis of the strong C(2)H(2) emission feature at 729 cm(-1) suggests an acetylene mole fraction in the range between 9 x 10(-8) and 9 x 10(-7). Vertical temperature profiles were derived between 30 and 1000 millibars at 70 degrees and 42 degrees S and 30 degrees N. Temperature maps of the planet between 80 degrees S and 30 degrees N were obtained for two atmospheric layers, one in the lower stratosphere between 30 and 120 millibars and the other in the troposphere between 300 and 1000 millibars. Zonal mean temperatures obtained from these maps and from latitude scans indicate a relatively warm pole and equator with cooler mid-latitudes. This is qualitatively similar to the behavior found on Uranus even though the obliquities and internal heat fluxes of the two planets are markedly different. Comparison of winds derived from images with the vertical wind shear calculated from the temperature field indicates a general decay of wind speed with height, a phenomenon also observed on the other three giant planets. Strong, wavelike longitudinal thermal structure is found, some of which appears to be associated with the Great Dark Spot. An intense, localizd cold region is seen in the lower stratosphere, which does not appear to be correlated with any visible feature. A preliminary estimate of the effective temperature of the planet yields a value of 59.3 +/- 1.0 kelvins. Measurements of Triton provide an estimate of the daytime surface temperature of 38(+3)(-4) kelvins.  相似文献   

Phytotoxic and antimicrobial activities of catechin derivatives     

Veluri R  Weir TL  Bais HP  Stermitz FR  Vivanco JM 《Journal of agricultural and food chemistry》2004,52(5):1077-1082

(+/-)-Catechin is a potent phytotoxin, with the phytotoxicity due entirely to the (-)-catechin enantiomer. (+)-Catechin, but not the (-)-enantiomer, has antibacterial and antifungal activities. Tetramethoxy, pentaacetoxy, and cyclic derivatives of (+/-)-catechin retained phytotoxicity. The results indicate that antioxidant properties of catechins are not a determining factor for phytotoxicity. A similar conclusion was reached for the antimicrobial properties. Centaurea maculosa (spotted knapweed) exudes (+/-)-catechin from its roots, but the flavanol is not re-absorbed and hence the weed is not affected. The much less polar tetramethoxy derivative may, however, be absorbed and hence be able to cause toxicity. Because of the combination of phytotoxicity and antimicrobial activity, (+/-)-catechin could be a useful natural herbicide and antimicrobial.  相似文献   

Utilization of mineral nitrogen in the subsoil by winter wheat     

H. Kuhlmann  P. B. Barraclough  A. H. Weir 《植物养料与土壤学杂志》1989,152(3):291-295

Uptake of nitrogen from the subsoil (30–200 cm) by winter wheat has been measured in field experiments on deep loess-parabrown soils in northern Germany and at Rothamsted (England) for different crop rotations and manuring schemes. The results can be summarised as follows:

• 1 The mineral nitrogen content of the subsoil varies widely depending on farming practice.
• 2 The effective depth limit for N uptake by winter wheat appears to be 150 cm.
• 3 Averaged over 22 sites, 33% of the total N uptake was from the subsoil (range 9–75%); 25% was from the 30–90 cm soil layer and 8% from the 90–150 cm soil layer.
• 4 Decreasing the N supply to the topsoil increased N uptake from the subsoil.
• 5 N uptake from the subsoil is not dependent on water uptake from the subsoil; nitrate is readily transported to absorbing roots by diffusion.
• 6 When deciding on the rate of fertilizer N to apply in early spring, soil mineral N to a depth of 90 cm should be taken into account. For subsequent dressings, the soil mineral N between 90–150 cm depth needs to be considered.

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In vitro and in vivo Development of Cloned Ovine Embryos using in vitro and in vivo Matured Oocytes     

P Holm  H Nagashima  F-J Sun  RF Seamark 《Reproduction in domestic animals》1995,30(3):125-128

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A one-way (non-rebreathing) valve suitable for use in gas analysis of exercising horses     

RF SLOCOMBE  WM BAYLY 《Australian veterinary journal》1993,70(4):151-152

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RADIOGRAPHIC APPEARANCE OF THE FEET OF MAMMOTH DONKEYS AND THE FINDING OF SUBCLINICAL LAMINITIS     

Michael  Walker  DVM  Tex  Taylor  DVM  Margaret  Slater  DVM  David  Hood  DVM  Vicki  Weir  ARRT  Jonelle  Elslander  RVT 《Veterinary radiology & ultrasound》1995,36(1):32-37

All feet of 10 clinically sound mammoth donkeys (Group I) were radiographed to determine the appearance of the distal phalanx. The distal phalanges had blunted to concave-shaped dorsal solar margins which varied in appearance from slight to pronounced. The distal phalanges of the forefeet were wider than those of the hindfeet, and also were positioned a greater distance from the dorsal aspect of the hoof wall. The greater distance between the dorsal aspect of the hoof wall and the distal phalanges seemed related to the presence of a periosteal-like bony proliferation on the dorsum of the distal phalanx. This bony proliferation occurred in those distal phalanges which also had radiographic findings consistent with pedal osteitis. Next, all feet of 5 additional mammoth donkeys (Group II) that were to be necropsied for various reasons, were examined similarly to Group I, necropsied and found to have laminitis. Only 2 of these 5 donkeys had been lame; only one had rotation of the distal phalanges (in the forefeet). Radiographic data from the 4 donkeys without rotation seemed most similar to that found in those Group I donkeys which had periosteal reactions on their distal phalanges. Conclusions from this study were that: 1) feet of mammoth donkeys have some anatomic differences from those of domestic horses, 2) subclinical laminitis and pedal osteitis can occur in mammoth donkeys, 3) rotation of the distal phalanx occurs in some, but not all laminitic donkeys, 4) laminitic changes may be more pronounced in their fore than in their hindfeet, and 5) additional studies of donkeys need to be done, examining both proven normal and confirmed laminitic feet.  相似文献   

Cerebral coenuriasis in a domestic cat     

RF SLOCOMBE  JH ARUNDEL  R. LABUC  MK DOYLE 《Australian veterinary journal》1989,66(3):92-93

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Estimating losses in the yield of winter wheat as a result of drought, in England and Wales     

A.H. Weir 《Soil Use and Management》1988,4(2):33-40

Abstract. A simple model for droughtiness, when linked to the distribution of soil types in England and Wales, is potentially valuable for estimating drought-induced losses of yield in winter wheat at either particular places or in larger areas of the country. The model defines droughtiness, D , in terms of the soil water extractable by the crop, AP , and the adjusted potential moisture deficit, MD :
D = AP − MD .
The model should represent well the growth of actual crops of winter wheat if AP , which is based on laboratory measurements, accurately simulates the extraction of soil water by roots, if MD represents the cumulative transpiration of water by wheat crops by mid-July, and if the latter is an appropriate date for testing the effect of drought on grain growth. These three assumptions have been investigated using measurements of artificially draughted crops of winter wheat.
The results indicate that mid-July is a good choice for a single date and MD a good representation of the water requirement of a wheat crop that has been draughted to the point where yield is beginning to be affected. For the deep-rooting crops studied, AP underestimates the soil water extracted by the crop, and therefore overestimates the susceptibility of the soil to drought
If average MD values are replaced by means and a standard deviation the resulting normal distribution of D -values can be used to assess the probability that drought will limit yields. When applied to a droughtiness map of England and Wales with AP -values used for the soils the model predicts that the soils growing wheat will be susceptible to drought in 16–84 years out of every 100. Our results suggest, however, that this probably applies to shallow rooting or diseased crops and that for deep-rooting, healthy crops the drought risk is much less serious.  相似文献   

The effect of drought on the root growth of winter wheat and on its water uptake from a deep loam     

A.H. Weir  P.B. Barraclough 《Soil Use and Management》1986,2(3):91-96

Abstract. Avalon winter wheat was grown on deep silty clay loam soil (Hook series) under a fixed shelter at Rothamsted with either full drought or irrigation from the end of March to July, 1982. During this time the irrigated crop used 295 mm of irrigation water plus 45 mm of stored soil water, while the droughted crop extracted 223 mm of water from the soil. The roots penetrated to at least 1.8m and water was extracted from 2 m depth.
Even with a fully developed root system the crops could transpire at the full rate of atmospheric demand only when the near-surface soil was well supplied with water. However, the draughted crop extracted enough water from the loamy sub-soil to maintain a reduced transpiration flow for a further nine weeks after the near-surface water was depleted. Thus crop growth was maintained with a loss at final harvest of only 10% in total dry weight and even less in grain yield.
A summary of other results confirm that yield losses due to drought have been reported only for light soils, except in the exceptional year of 1976, and that drought is not normally an important factor affecting yields of winter wheat in the UK.  相似文献   

Effect of total phosphorus and phytate-phosphorus intake on phosphorus digestibility in horses     

L.K. Warren  J.M. Weir  P.A. Harris  J. Kivipelto 《Journal of Equine Veterinary Science》2013

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