EFFECT OF DAY-NIGHT TEMPERATURE REGIMES ON GROWTH AND MORPHOLOGICAL DEVELOPMENT OF TIMOTHY PLANTS DERIVED FROM WINTER AND SUMMER TILLERS     

Dale  Smith 《Grass and Forage Science》1972,27(2):107-110

Winter (vernalized) and summer (non-vernalized) timothy tillers were grown to anthesis in day/night temperature regimes of 32/26°, 27/21°, 21/15°, and 15/10°C. Herbage and total plant yields, total leaf-blade number and area, and total plant growth-rate were highest, or very nearly so, in the 21/15°C regime for both the winter and summer plants. However, summer plants reached anthesis 13 to 14 days later than winter plants in each temperature regime. Even though virtually all primary shoots produced an infiorescence, summer plants had significantiy more leaves and leaf-blade area, produced significantiy higher yields of leaf blade, stem plus sheath, stubble, and root tissues and had a significantly higher total plant growth rate than winter plants in each temperature regime.  相似文献   

Indices of landscape pattern   总被引：171，自引：1，他引：170  

R. V. O'Neill  J. R. Krummel  R. H. Gardner  G. Sugihara  B. Jackson  D. L. DeAngelis  B. T. Milne  M. G. Turner  B. Zygmunt  S. W. Christensen  V. H. Dale  R. L. Graham 《Landscape Ecology》1988,1(3):153-162

Landscape ecology deals with the patterning of ecosystems in space. Methods are needed to quantify aspects of spatial pattern that can be correlated with ecological processes. The present paper develops three indices of pattern derived from information theory and fractal geometry. Using digitized maps, the indices are calculated for 94 quadrangles covering most of the eastern United States. The indices are shown to be reasonably independent of each other and to capture major features of landscape pattern. One of the indices, the fractal dimension, is shown to be correlated with the degree of human manipulation of the landscape.  相似文献   

Evaluation of 3 Assays for Failure of Passive Transfer in Calves   总被引：2，自引：1，他引：1  

Jeff W. Tyler  Dale D. Hancock  Steven M. Parish  Douglas E. Rea  Thomas E. Besser  Sean G. Sanders  Leilani K. Wilson 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1996,10(5):304-307

This study examined the sensitivity, specificity, predictive values, and classification accuracy of 3 commonly used screening tests for failure of passive transfer: the sodium sulfite turbidity test, the zinc sulfate turbidity test, and re-fractometry relative to serum immunoglobulin G₁, (IgG₁) concentrations determined by radial immunodiffusion. Serum samples were obtained from 242 calves ranging from 1 to 8 days of age. Using a serum concentration of 1,000 mg/dL IgG₁ to define adequate passive transfer, the zinc sulfate test had a sensitivity of 1.00 and a specificity of 0.52 in the detection of inadequate passive transfer. The endpoint of the test appeared to be higher than desired; calves testing negative had mean serum IgG₁ concentration of 955 mg/dL and a large proportion of calves with adequate passive transfer were misclassified as positive for failure of passive transfer. Using the qualitative zinc sulfate test, the percentage of calves correctly classified with regard to passive transfer status was less than that observed with either the sodium sulfite test or refractometry. The sensitivity of the sodium sulfite assay was 0.85 at a 1+ endpoint and 1.00 at a 2 or 3+ endpoint. The specificity of the sodium sulfite assay varied from 0.87 at a 1+ endpoint and 0.56 at a 2+ endpoint. The sensitivity and specificity of refractometry varied from 0.01 to 1.00 depending on the choice of endpoint. Refractometry correctly classified the largest proportion of calves with regard to their passive transfer status at test endpoints of 5.0 and 5.5 g/dL, 83% and 82% respectively. The highest percentages of calves correctly classified occurred with the sodium sulfite test using a 1+ endpoint (86.30%) and refractometry using a 5.0 g/dL endpoint (83.00%). A regression equation was developed that permitted calculation of an optimal endpoint for refractometric determinations of total serum protein concentration. A serum protein concentration of 5.2 g/dL was equivalent to 1,000 mg/dL serum IgG₁. Optimal selection of tests for passive transfer status in calves will be governed by the prevalence of failure of passive transfer, test performance, and the anticipated costs of classification errors.  相似文献   

RETROSPECTIVE ASSESSMENT OF COMPUTED TOMOGRAPHIC IMAGING OF FELINE SINONASAL DISEASE IN 62 CATS     

William C.  Schoenborn  DVM  Erik R.  Wisner  DVM  Philip P.  Kass  DVM  PhD  Margaret  Dale 《Veterinary radiology & ultrasound》2003,44(2):185-195

Sixty-two cats with sinonasal disease were evaluated with computed tomography. Findings that may lead to a computed tomographic diagnosis of nasal neoplasia versus rhinitis included osteolysis of the paranasal bones, moderate to severe turbinate destruction, lysis of the nasal septum, the presence of a homogenous space occupying mass, and extension of the disease process into the orbit or facial soft tissues. These findings were not pathognomonic for neoplasia and may be associated with severe rhinitis; therefore, nasal biopsy was recommended. When compared with parallel radiographic studies, computed tomography was not more sensitive than radiographs at detecting the presence of nasal cavity abnormalities in cats with referable clinical signs but was more sensitive at localizing these changes and determining the extent of disease.  相似文献   

Quantifying scale-dependent effects of animal movement with simple percolation models   总被引：4，自引：0，他引：4  

R. H. Gardner  R. V. O'Neill  M. G. Turner  V. H. Dale 《Landscape Ecology》1989,3(3-4):217-227

A simple model of animal movement on random and patterned landscapes was used to explore the problems of extrapolating information across a range of spatial scales. Simulation results indicate that simple relation- ships between pattern and process will produce a variety of scale-dependent effects. These theoretical studies can be used to design experiments for determining the nature of scale-dependent processes and to estimate parameters for extrapolating information across scales.  相似文献   

Toxicological pathology of cockleburs (Xanthium spp.) for broiler chickens.     

M A Goodwin  E T Mallinson  J Brown  E C Player  K S Latimer  N Dale  W V Shaff  T G Dickson 《Avian diseases》1992,36(2):444-446

Spiking mortality syndrome (SMS) in chickens resembles cocklebur toxicity in cattle, sheep, pigs, and rats. In order to determine if cockleburs are toxic to broiler chicks, crushed burs were fed (25% wt:wt) to broilers for 21 days. Ingestion of cockleburs resulted in significant failure to properly gain body weight. Otherwise, chicks did not develop clinical signs of illness or gross or microscopic lesions. Although there were some significant differences in serum chemistry values among chick groups, there were no consistent patterns. Severe hypoglycemia is said to be a characteristic finding in chicks that die with SMS. Because glucose levels were not low in chicks that were fed cockleburs, we feel certain that cockleburs do not cause SMS.  相似文献   

Imidazolinone inhibition of acetohydroxyacid synthase in vitro and in vivo     

Mark A. Stidham  Dale L. Shaner 《Pest management science》1990,29(3):335-340

Imidazolinone herbicides inhibit the first enzyme of branched-chain amino acid biosynthesis, acetohydroxyacid synthase. The inhibition of the enzyme in vitro by these herbicides increases with incubation time, but is not irreversible, as deduced by reaction progress curves. In contrast to this result is the apparent irreversible inhibition of the enzyme by these imidazolinones that occurs when the herbicide is applied to intact corn plants. Plants treated with imidazolinone herbicide and then extracted showed dramatically reduced enzyme activity. This effect on extractable enzyme level occurred with several different imidazolinone herbicides in either foliar or soil application. The decrease in extractable enzyme activity could be observed within four hours after treatment. Herbicides other than imidazolinones did not reduce the extractable enzyme level. These findings suggest that the enzyme- imidazolinone interaction in vivo may be different from the interaction observed in vitro.  相似文献   

Experience with patterns of change in soil carbon resulting from forest plantation establishment in eastern Australia     

John Turner  Marcia J. Lambert  Dale W. Johnson 《Forest Ecology and Management》2005,220(1-3):259-269

Forest plantations are extensively established in eastern Australia for production of timber products and more recently, potentially for sequestration of carbon. Intensive management of these plantations involves clearing of existing vegetation, often using fire, ripping and/or mounding of the soil and weed control, followed by planting, use of fertilizers, and subsequent tending. The plantations are managed on a 10–30-year rotation and often have high growth rates and accumulation of carbon. However, after establishment, there are reduced inputs of carbon into the soil from prior vegetation or rapidly growing weeds, together with accelerated decomposition of soil organic matter as a result of disturbance, and this leads to a net loss of soil organic carbon. In some systems this loss of soil organic carbon is not balanced by carbon biomass sequestration until 5–10 years after establishment and on some sites, a reduction in soil organic carbon may remain until the end of the rotation. The patterns of accumulation and loss of carbon vary according to location, soil type and plantation management system. The effects of intensive forest establishment on soil organic carbon were evaluated in a number of studies in eastern Australia using time sequence and chronosequence studies and comparisons of plantation soils with those from adjacent undisturbed sites. There was a general pattern of reduced carbon in surface soil immediately after plantation establishment and with time this extended deeper into the soil profile. The actual quantities varied greatly depending on the soil type. The decline was primarily a result of losses of labile carbon and was greater when the previous land use had essentially been native vegetation or highly improved pastures as opposed to regrowth woodland, or native pasture, or degraded land. In the absence of further disturbance, soil organic carbon can accumulate to pre-establishment levels but many short rotation plantations are terminated prior to this being attained. The potential upper level of accumulation of soil carbon can be increased by alteration of the soil nutritional status using fertilizer application.  相似文献   

What is leadership?     

Klingborg DJ  Moore DA  Varea-Hammond S 《Journal of veterinary medical education》2006,33(2):280-283

The demand for more effective leadership is heard throughout the health professions. Modern concepts of leadership differ from the traditional definition of a charismatic individual leader. Historically, leadership has been vested in positions, while today leadership is seen as a role one moves continuously into and out of, depending on the circumstance. Leadership ideas have evolved so that newer characteristics of leaders include being a team builder; possessing creative and strategic thinking skills; demonstrating honesty and integrity; and having the ability to motivate others to action. This article discusses some of the history of leadership, current thoughts on attributes of effective leaders, and the differences and similarities between leaders and managers; identifies selected teachable leadership tools; and describes various styles and purposes of existing leadership programs.  相似文献   

Evaluation and implementation of a potential diagnostic molecular marker for H1‐conferred potato cyst nematode resistance in potato (Solanum tuberosum L.)     

Lee Schultz  Noel O. I. Cogan  Karen McLean  M. Finlay B. Dale  Glenn J. Bryan  John W. Forster  Anthony T. Slater 《Plant Breeding》2012,131(2):315-321

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