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  • 1990-1994  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 48 (1993), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Seven cultivars of white clover (Trifolium repens L.) (Kent, S184, Huia, Menna, Donna, Alice and Nesta) and a commercial mixture, ‘Ensign’, were strip-seeded into an upland perennial rye-grass (Lolium perenne L.) sward in late June 1986. Swards were first grazed by sheep, either on 5/6 August (early) or on 19/20 August (late) and then every 14–21 days (frequently) or 28–42 days (infrequently) during 1986, followed by a common grazing regime in 1987. During April to mid-June 1988 the swards received either a moderate amount of nitrogen or none and were cut frequently or once only in mid-June. Growth of individual seedlings was assessed before and after grazing during 1986 and stolon accumulation and distribution and sward colonization were assessed during 1987 and 1988.All cultivars emerged rapidly and satisfactorily and there were no consistent significant differences in the overall dry matter accumulation per seedling during establishment. During the first autumn the proportion of the aboveground biomass removed during grazing was smallest in Kent (c. 20%) and largest in Nesta (c. 40%). Kent and S184 produced most leaves and stolons and the greatest length of stolons per seedling and per individual stolon, and Nesta and Alice the fewest leaves and stolons and shortest stolons. Seedlings grazed early had heavier and longer stolons than those grazed late; those grazed frequently had more leaves, stolons and growing points than those grazed infrequently, especially following early grazing.During 1987 Kent and S184 had consistently the largest number of stolon growing points, and weight and length of stolons per unit area; these two cultivars and Nesta also colonized the sward more rapidly than the other cultivars. All cultivars contributed substantially and similarly to herbage production in late September. There were no residual effects of the 1986 treatments after the summer of 1987.During 1988 additions of nitrogen fertilizer at 100 kg N ha-1 or allowing the herbage to remain undefoliated between mid-April and mid-June both independently halved the number of stolon growing points per unit area; together they reduced it by 80%. Nitrogen also, on average, halved stolon weights but less so in Nesta, Alice and Huia and more so in all other cultivars. Infrequent defoliation greatly decreased stolon weights in Kent and S184 but had no significant effects on the other cultivars. Sward colonization was almost complete by June and entirely so by October for all cultivars in all treatments.Implications of the results for the after-management of strip-seeded white clover are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 45 (1990), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Small plots of a Festuca-Agrostis upland sward on a peaty gley podsol were strip-seeded during late June 1986 with white clover cvs Aberystwyth S184 or Menna at 4 kg ha−1 and defoliated early (20 August) or late (3 September) and then frequently or infrequently (every 2 weeks or 4 weeks) until the end of September. All plots were defoliated in early November, at 3-weekly intervals during the growing season in 1987 and then grazed rotationally during 1988.Satisfactory seedling establishment, representing 46% emergence, was achieved 5 weeks after sowing. The differential defoliation regimes had no persistent significant effects on clover development. S184 soon produced more leaves per seedling than Menna and a smaller proportion of its leaf number and weight were removed at each defoliation. Following large losses of leaves over the 1986–87 winter, SI84 had significantly more leaves per stolon than Menna; subsequently it also colonized the sward at a quicker rate. During 1987 amounts of herbage harvested (6.1 t ha−1) were similar with the two clover cultivars, with S184 contributing 47% and Menna 44% of this respectively. SI84 made a larger contribution to yield during May and June but Menna was more productive during September and October. During 1988 clover populations were maintained with rotational grazing without additional fertilizer inputs.The results show that, despite initial soil and climatic contraints, both small and medium-leaved clovers can be strip-seeded into upland swards with large subsequent benefits to yield and herbage quality. However, they also indicate the need for further experiments to determine the influence of sward morphology and defoliation regime on stolon branching rates and accumulation of growing points which, in turn, govern sward colonization.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Nous avons étudié une série de 22 cancers médullaires (CM), primitifs et secondaires, par l'immunohistochimie (IHC) et par l'hybridation in situ (HIS) afin de localiser respectivement d'une part les peptides calcitonine et la somatostatine et d'autre part les mRNA de la calcitonine et la somatostatine. Toutes les tumeurs étaient positives pour le peptide calcitonine par HIS mais présentaient par ailleurs une hétérogénéité intercellulaire beaucoup de cellules n'ayant pas de calcitonine détectable. Le mRNA de la calcitonine, détecté par HIS, était uniformément distribué indiquant que certaines cellules tumorales CM peuvent à la fois assurer la synthèse et stocker la calcitonine alors que d'autres perdent leur pouvoir de stockage mais pas leurs propriétés de synthèse. Les peptides de la somatostatine et la calcitonine ont été retrouvés dans les tumeurs provenant de 15 patients. Au contraire de ce que l'on observe avec la calcitonine, le mARN de la somatostatine et le peptide étaient généralement repartis dans des cellules dispersées. Lorsque la corrélation a été recherchée, la même cellule pouvait être positive pour la somatostatine par l'IHC et par HIS. Dans une même tumeur, cependant, il y avait beaucoup plus de cellules positives pour le mARN que pour les peptides, suggérant que seule une petite proportion de cellules avait gardé leur capacité de stocker le peptide. La variation du contenu cellulaire de calcitonine immunoréactive est interprétée comme étant le résultat soit d'une augmentation de la croissance cellulaire, soit d'une diminution du stockage du peptide par la tumeur. La corrélation entre le mARNde la somatostatine et le peptide était bonne, mais cette corrélation était notée surtout dans les cellules dispersées, la majorité des cellules tumorales étant négatives et pour le mARN et pour le peptide. On suggère que la production de somatostatine peut être associée à une réduction de la croissance cellulaire soit par un étape intermédiaire soit directement par l'effet de l'hormone. Nous concluons aussi que les études par HIS pour les substances mARN et l'IHC pour les peptides sont utiles pour la localisation de la production hormonale des tumeurs endocrines.
    Abstract: Resumen Hemos estudiado una serie de 22 carcinomas medulares tiroideos humanos (CMT), tanto primarios como metastásicos, utilizando immunocitoquímica (ICQ) para localizar calcitonina, y péptido somatostátinico e hibridación in situ (HIS) para localizar calcitonina y somatostatina mRNA. Todos los tumores fueron positivos para péptido calcitotínico con ICC, que con frecuencia mostró considerable heterogenecidad celular, con muchas células con niveles no detectables de calcitonina. Sin embargo, la calcitonina mRNA localizada por HIS apareció más uniformemente distribuída, indicando que las células del CMT pueden retener la capacidad tanto de sintetizar como la de almacenar calcitonina, mientras otras pierden su capacidad de almacenar mas no de sintetizar. El péptido somatostátinico y la somatostatina mRNA fueron hallados en los tumores de 15 pacientes. en contraste con el patrón observado con la calcitonina, la somatostatina mRNA y el péptido usualmente fueron hallados en células únicas dispersas. Cuando fue posible la correlación, la misma célula mostró positividad para la somatostatina mRNA en HIS y positividad para el péptido en ICQ. Sin embargo, en un tumor muchas más células fueron positivas para mRNA que para el péptido, lo cual sugiere que sólo una proporción de las células retiene la habilidad de almacenar el péptido. La variación en el contenido de calcitonina inmunoreactiva es interpretada como el resultado o bien de una incrementada rata de crecimiento rumoral, o como una reducida capacidad para almacenar el péptido en un tumor menos diferenciado. Con la somatostatina se encontró una muy buena correlación entre el contenido de mRNA y de péptido, pero esto ocurrió sólamente en células ampliamente dispersas, con la gran mayoría de las células tumorales permaneciendo negativas tanto para péptido como para mRNA. Se sugiere que la producción de somatostatina puede estar asociada con una reducción en el crecimiento de la célula concerniente, bien a través de una fase de diferenciación o bien como efecto directo de la hormona. También es nuestra conclusión que los estudios de localización de la producción hormonal en los tumores endocrinos se benefician de la aplicación combinada de HIS para mRNA y de ICQ para péptido.
    Notes: Abstract We have studied a series of 22 human medullary carcinomas (MCTs), both primary and metastatic, using immunocytochemistry (ICC) to localize calcitonin and somatostatin peptide and in situ hybridization (ISH) to localize calcitonin and somatostatin mRNA. All tumors were positive for calcitonin peptide with ICC, which often showed considerable intercellular heterogeneity, with many cells having undetectable levels of calcitonin. However, calcitonin mRNA localized by ISH was much more uniformly distributed, indicating that MCT tumor cells may retain the capacity to both synthesize and store calcitonin, whereas others lose their storage but not their synthetic capacity. Somatostatin peptide and mRNA were found in tumors from 15 patients. In contrast to the pattern seen with calcitonin, somatostatin mRNA and peptide were usually found in single scattered cells. When correlation was possible, the same cell showed positivity for somatostatin mRNA on ISH and positivity for somatostatin peptide on ICC. However, in one tumor many more cells were positive for mRNA than for peptide, suggesting that only a proportion of cells retained the ability to store the peptide. The variation in cellular content of immunoreactive calcitonin is interpreted as resulting from either an increased tumor growth rate r reduced ability to store peptide in a less differentiated tumor. With somatostatin there was good correlation between mRNA and peptide content, but it occurred in single widely scattered cells, most tumor cells being negative for both peptide and mRNA It is suggested that somatostatin production might be associated with a reduction in the growth of the cell concerned, either through a differentiation step or through a direct effect of the hormone. We also conclude that studies of the localization of hormone production in endocrine tumors benefit from the combined application of ISH for mRNA and ICC for peptide.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 19 (1992), S. 125-130 
    ISSN: 1619-7089
    Keywords: Gamma-camera ; Quality control ; Uniformity ; Cusum analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Gamma-camera uniformity is often monitored for quality control of performance. Many parameters can be derived from computer analysis of the image of a uniform (flood) source to obtain quantitative measures of uniformity. However, it is not clear which best reflect changes in uniformity, or how action levels should be set. The latter are essential for an automated analysis. To compare the various parameters and assess two techniques used for their analysis, a series of technetium-99m flood images were obtained consecutively. After establishing a baseline from repeated images, uniformity was degraded by offsetting the pulse height analyser (PHA) window by a small amount. Nine non-uniformity parameters were calculated for each flood image, including the Department of Health and Social Security (DHSS) and National Electrical Manufacturers Association (NEMA) integral and differential uniformities, the uniformity index and the percentage of pixels more than 5% from the mean. All parameters were calculated for both central field-of-view (CFOV) and useful field-of-view (UFOV). Eighty such trials were carried out on two gamma-cameras. The PHA offsets ranged from 1–10 keV The two techniques used for analysis were the control chart and cusum analysis. Decision levels were set for each parameter, as multiples of SD for the control charts or by varying the dimensions of a truncated V-mask for cusum analysis. Receiver operating characteristic (ROC) curves were then used for an objective comparison of the parameters and of the analysis techniques. The area under the ROC curve was used to rank the parameters in order of sensitivity to change in uniformity. The uniformity index and NEMA integral non-uniformity were found to be the most sensitive. Cusum analysis improved the sensitivity of those parameters that appeared to have low sensitivity to change when subjected to control chart analysis. However, there was little difference between the two analysis techniques for the more sensitive parameters. The ROC curves could also be used to provide a method for selecting decision levels, hence establishing an automated method for gamma-camera quality control.
    Type of Medium: Electronic Resource
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