Surface ices and the atmospheric composition of pluto     

Owen TC  Roush TL  Cruikshank DP  Elliot JL  Young LA  de Bergh C  Schmitt B  Geballe TR  Brown RH  Bartholomew MJ 《Science (New York, N.Y.)》1993,261(5122):745-748

Observations of the 1.4- to 2.4-micrometer spectrum of Pluto reveal absorptions of carbon monoxide and nitrogen ices and confirm the presence of solid methane. Frozen nitrogen is more abundant than the other two ices by a factor of about 50; gaseous nitrogen must therefore be the major atmospheric constituent. The absence of carbon dioxide absorptions is one of several differences between the spectra of Pluto and Triton in this region. Both worlds carry information about the composition of the solar nebula and the processes by which icy planetesimals formed.  相似文献   

Leave regulation to the FDA     

Hughes OC 《Science (New York, N.Y.)》2008,321(5888):490

  相似文献   

Retraction     

Witte ON  Kabarowski JH  Xu Y  Le LQ  Zhu K 《Science (New York, N.Y.)》2005,307(5707):206

  相似文献   

Evaluation of spectrophotometric and HPLC methods for shikimic acid determination in plants: models in glyphosate-resistant and -susceptible crops     

Zelaya IA  Anderson JA  Owen MD  Landes RD 《Journal of agricultural and food chemistry》2011,59(6):2202-2212

Endogenous shikimic acid determinations are routinely used to assess the efficacy of glyphosate in plants. Numerous analytical methods exist in the public domain for the detection of shikimic acid, yet the most commonly cited comprise spectrophotometric and high-pressure liquid chromatography (HPLC) methods. This paper compares an HPLC and two spectrophotometric methods (Spec 1 and Spec 2) and assesses the effectiveness in the detection of shikimic acid in the tissues of glyphosate-treated plants. Furthermore, the study evaluates the versatility of two acid-based shikimic acid extraction methods and assesses the longevity of plant extract samples under different storage conditions. Finally, Spec 1 and Spec 2 are further characterized with respect to (1) the capacity to discern between shikimic acid and chemically related alicyclic hydroxy acids, (2) the stability of the chromophore (t1/2), (3) the detection limits, and (4) the cost and simplicity of undertaking the analytical procedure. Overall, spectrophotometric methods were more cost-effective and simpler to execute yet provided a narrower detection limit compared to HPLC. All three methods were specific to shikimic acid and detected the compound in the tissues of glyphosate-susceptible crops, increasing exponentially in concentration within 24 h of glyphosate application and plateauing at approximately 72 h. Spec 1 estimated more shikimic acid in identical plant extract samples compared to Spec 2 and, likewise, HPLC detection was more effective than spectrophotometric determinations. Given the unprecedented global adoption of glyphosate-resistant crops and concomitant use of glyphosate, an effective and accurate assessment of glyphosate efficacy is important. Endogenous shikimic acid determinations are instrumental in corroborating the efficacy of glyphosate and therefore have numerous applications in herbicide research and related areas of science as well as resolving many commercial issues as a consequence of glyphosate utilization.  相似文献   

Terminology for classifying the porcine reproductive and respiratory syndrome virus (PRRSV) status of swine herds     

Holtkamp DJ  Polson DD  Torremorell M  Morrison B  Classen DM  Becton L  Henry S  Rodibaugh MT  Rowland RR  Snelson H  Straw B  Yeske P  Zimmerman J;American Association of Swine Veterinarians;United States Department of Agriculture PRRS-Coordinated Agricultural Project 《Tier?rztliche Praxis. Ausgabe G, Grosstiere/Nutztiere》2011,39(2):101-112

Standardized terminology for the porcine reproductive and respiratory syndrome virus (PRRSV) status of swine herds is necessary to facilitate communication between veterinarians, swine producers, genetic companies, and other industry participants. It is also required for implementation of regional and national efforts towards PRRSV control and elimination. The purpose of this paper is to provide a herd classification system for describing the PRRSV status of herds, based upon a set of definitions reflecting the biology and ecology of PRRSV. The herd classification system was developed by a definitions committee formed jointly by the American Association of Swine Veterinarians (AASV) and the United States Department of Agriculture PRRS-Coordinated Agricultural Project, and was approved by the AASV Board of Directors on March 9, 2010. The committee included veterinarians from private practice and industry, researchers, and representatives from AASV and the National Pork Board. Breeding herds, with or without growing pigs on the same premises, are categorized as Positive Unstable (Category I), Positive Stable (Category II), Provisional Negative (Category III), or Negative (Category IV) on the basis of herd shedding and exposure status. Growing-pig herds are categorized as Positive or Negative. Recommended testing procedures and decision rules for herd classification are detailed.  相似文献   

Benchmark study on glyphosate-resistant crop systems in the United States. Part 2: Perspectives     

Owen MD  Young BG  Shaw DR  Wilson RG  Jordan DL  Dixon PM  Weller SC 《Pest management science》2011,67(7):747-757

A six-state, 5 year field project was initiated in 2006 to study weed management methods that foster the sustainability of genetically engineered (GE) glyphosate-resistant (GR) crop systems. The benchmark study field-scale experiments were initiated following a survey, conducted in the winter of 2005-2006, of farmer opinions on weed management practices and their views on GR weeds and management tactics. The main survey findings supported the premise that growers were generally less aware of the significance of evolved herbicide resistance and did not have a high recognition of the strong selection pressure from herbicides on the evolution of herbicide-resistant (HR) weeds. The results of the benchmark study survey indicated that there are educational challenges to implement sustainable GR-based crop systems and helped guide the development of the field-scale benchmark study. Paramount is the need to develop consistent and clearly articulated science-based management recommendations that enable farmers to reduce the potential for HR weeds. This paper provides background perspectives about the use of GR crops, the impact of these crops and an overview of different opinions about the use of GR crops on agriculture and society, as well as defining how the benchmark study will address these issues.  相似文献   

Ionic concentrations in a blanket peat bog in northern England and correlations with deposition and climate variables   总被引：1，自引：0，他引：1  

J. K. Adamson  W. A. Scott  A. P. Rowland  & G. R. Beard 《European Journal of Soil Science》2001,52(1):69-79

Soil solution was collected to identify seasonal trends in its chemistry and to examine relationships between the concentrations of ions and variables that may control them. Samples were collected fortnightly at 10 cm and 50 cm depth in a blanket peat soil at Moor House–Upper Teesdale National Nature Reserve in the northern Pennine uplands of England. Dissolved organic carbon at 10 cm peaked each summer and correlated most strongly with temperature. At both depths Na⁺ and Cl^– were the dominant ions, reflecting the oceanic climate. Over the 3‐year sampling period, concentrations of the principal anions and cations at 10 cm varied little except during the autumns of 1994 and 1995 following unusually dry summers. At these times concentrations of SO₄^2–‐S increased from < 3 μmol to a maximum of 430 μmol and were balanced by smaller increases in Na⁺, Mg²⁺, Ca²⁺ and H⁺. The SO₄^2– concentration at 10 cm was most strongly correlated with depth to the water Table 3 weeks prior to sampling. At 50 cm depth in the peat a small increase in SO₄^2– occurred only during the autumn of 1995, and the concentration of SO₄^2– at this depth correlated most strongly with that at 10 cm. At neither depth were there any strong correlations with deposition. The increase in H⁺ concentration associated with the peak in SO₄^2– at 10 cm depth represents a fall in pH from usual values around 4.2 to 3.5.

Table 3. Deposition flux of ions in bulk precipitation at Moor House from weekly samplings 1994 to 1996 in kg ha^?1 year^?1. The UK flux is derived from 32 sites of the United Kingdom Precipitation Composition Monitoring Network 1992 to 1994 and the standard deviation (SD) relates to the variation between these sites ( Review Group on Acid Rain, 1997 )

	Moor House flux	UK flux	UK SD
H+	0.31	0.26	0.10
Ca2+	4.07	3.58	1.86
Mg2+	3.37	3.62	2.62
K+	1.54
Fe2+	0.73
Al3+	0.44
Na+	29.32	25.77	19.27
Cl–	51.14	45.96	32.39
NO3–‐N	4.01	3.20	1.05
NH4+‐N	4.85	3.63	1.74
SO42–‐S	8.98	7.98	3.09
PO43–‐P	0.01

Citing Literature

Volume 52 , Issue 1 March 2001

Pages 69-79  相似文献   

Systemic cartilage defect in a calf     

P Wild  A C Rowland 《Veterinary pathology》1978,15(3):332-338

A 6-month-old Ayrshire calf had a systemic growth defect of cartilage. The most severe changes occurred in articular cartilage and epiphyseal plates of long bones where disturbance of ossification, necrosis, erosion, vascular invasion, proliferation of cartilaginous and fibrous tissue were seen. The lesions probably were the result of a failure in the initial phases of ossification and mechanical pressure was responsible for their severity in the cartilage of the limbs.  相似文献   

Chemotherapy of canine and feline neoplasia     

D E Bostock  L N Owen 《The Journal of small animal practice》1972,13(7):359-367

  相似文献   

Jejuno- or ileocecal anastomosis performed in seven horses exhibiting colic.          下载免费PDF全文

R R Owen  P W Physick-Sheard  B J Hilbert  F D Horney    D G Butler 《The Canadian veterinary journal. La revue veterinaire canadienne》1975,16(6):164-169

  相似文献