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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 29 (1991), S. 9-20 
    ISSN: 1573-0867
    Keywords: Sub-Saharan Africa ; climate ; rainfall ; erodibility ; mulch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The alarming food deficits projected for sub-Saharan African from recent production figures make it mandatory that no effort be spared in reversing the trend of declining yields. Developing better understanding of such climate-related constraints as high intensity storms, inadequate rainfall or poor rainfall distribution, high temperatures and high evaporative demands, excessive rainfall and high erodibility of soils will result in measures that can overcome or mitigate these constraints.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé La localisation des tumeurs parathyroïdiennes par les différents procédés d'imagerie et la valeur respective des différentes méthodes prêtent encore à discussion. Les auteurs ont effectué une étude prospective à l'aveugle pour apprécier l'efficacité propre à chaque méthode chez 40 malades atteints d'hyperparathyroïdisme qui furent soumis avant l'intervention à une scintigraphie au Tc99m, à une exploration tomodensitométrique et à une échographie temps réel. Chaque étude fut pratiquée et interprétée de manière indépendante. Les 40 malades furent opérés et soumis à une parathyroïdectomie qui permit de comparer les constatations opératoires et les données de l'imagerie. La sensibilité respective des 3 procédés fut de 72% pour la scintigraphie, de 72% pour la tomodensitométrie et de 57% pour l'échographie avec une spécificité de 93% pour la première, de 92% pour la seconde et de 96% pour la troisième. En ce qui concerne les lésions situées au-dessous de la thyroïde (thymus et médiastin) le taux de sensibilité fut de 86% pour la scintigraphie, de 29% pour la tomodensitométrie et de 20% pour la sonographie cependant que celui de la spécificité était de 100%. Chez les hyperparathyroïdiens qui avaient subi une exploration défaillante les tumeurs parathyroïdiennes furent décelées avec un taux de sensibilité de 88% pour la scintigraphie, de 57% pour la tomodensitométrie et de 67% pour la sonographie, le taux de spécificité étant de 100% pour la première, de 71% pour la seconde et de 100% pour la troisième. La scintigraphie complétée par la tomodensitométrie représente la meilleure stratégie chez les sujets qui présentent une hyperparathyroïdie persistante après une opération négative et pour les lésions qui sont situées audessous de la thyroïde. Si l'on tient compte du fait que les chirurgiens spécialisés dans la chirurgie parathyroïdienne obtiennent la guérison de l'hyperparathyroïdisme dans au moins 93% des cas, ces méthodes d'exploration onéreuses ne paraissent pas indispensables à moins d'un échec de l'intervention initiale.
    Abstract: Resumen Existe controversia en cuanto a las ventajas y adecuación de las modalidades corrientes de imagenología para la localización de tumores paratiroideos. Hemos realizado un estudio prospectivo y ciego para comparar la eficacia de 3 modalidades diferentes de imagenología en 40 pacientes con hiperparatiroidismo primario (HPT). Los pacientes con HPT fueron examinados preoperatoriamente con centelleografía computadorizada con talium 201/tecnecio-99m (CTT), tomografía computadorizada de alta resolución GE 9800 (TC), y sonografía de tiempo real de alta resolución de 7.5 MHz (US). Cada estudio fue realizado e interpretado en forma independiente. Los pacientes fueron sometidos luego a exploración quirúrgica cervical y a paratiroidectomía, lo cual hizo posible la correlación clínica entre los hallazgos patológicos y los resultados de la imagenología. Las sensibilidades globales de las 3 modalidades imagenológicas fueron: CTT-72%, TC-72% y US-57%, con especificidades de: CTT-93%, TC-92% y US-96%. Para lesiones localizadas por debajo de la glándula tiroides (lengüeta tímica y mediastino), las sensibilidades fueron de: CTT-86%, CT-29% y US-20%, todas con especificidades de 100%. En aquellos pacientes con HPT, exhibiendo previas exploraciones fallidas del cuello, los tumores paratiroideos fueron detectados con sensibilidades de: CTT-88%, TC-57% y US-67%, con especificidades de 100%, 71% y 100% respectivamente. La CTT con CT subsiguiente parece ser una estrategia imagenológica óptima para pacientes con HPT con exploración cervical fallida previa o con sospecha de lesiones ubicadas por debajo de la glándula tiroidea. Teniendo en cuenta que los cirujanos experimentados en cirugía paratiroidea exhiben tasas de curación de 93% o más en pacientes con HPT sin exploración cervical previa, estas modalidades de imagenología pueden no ser justificadas desde el punto de vista de costo/beneficio y por consiguiente no estar indicadas en tales pacientes.
    Notes: Abstract Controversy exists concerning the advantages and appropriateness of current imaging modalities of the localization of parathyroid tumors. We conducted a prospective, blinded study to compare the efficacy of 3 different imaging modalities in 40 patients with primary hyperparathyroidism (HPT). Patients with HPT were examined preoperatively by computer-assisted thallium-201/technetium-99m scintigraphy (TTS), high-resolution (GE 9800) computed tomography (CT), and high-resolution (7.5 MHz) real-time sonography (US). Each study was performed and interpreted independently. These patients then had a neck exploration and parathyroidectomy which allowed for clinical correlation of pathologic findings with the imaging results. Overall sensitivities of the 3 imaging modalities were TTS-72%, CT-72%, and US-57%, with specificities of TTS-93%, CT-92%, and US-96%. For lesions located below the thyroid (thymic tongue and mediastinum), sensitivities were TTS-86%, CT-29%, and US-20%, all with specificities of 100%. In those HPT patients presenting with prior failed neck explorations, parathyroid tumors were detected with sensitivities of TTS-88%, CT-57%, and US-67%, with specificities of 100%, 71%, and 100%, respectively. TTS with subsequent CT appears to be an optimal imaging strategy for HPT patients with prior failed neck explorations or suspected lesions below the thyroid. Since surgeons experienced in parathyroid surgery have a cure rate of 93% or greater in HPT patients without prior neck exploration, these imaging modalities may not be cost-effective and thus not indicated for these patients.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 85 (1985), S. 267-277 
    ISSN: 1573-5036
    Keywords: Alley cropping ; Leucaena prunings ; Light incidence ; Maize and cowpea yields ; Soil nutrient and moisture status
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The potential of alley cropping maize and cowpea with the giant Leucaena (Leucaena leucocephala (Lam) de Wit) cultivar K-28 was studied on an Entisol (Psammentic Ustorthent) in Southern Nigeria. In this trial the crops were grown in 4 m wide alleys formed by periodically pruned leucaena hedgerows. The effect of application of leucaena prunings, nitrogen fertilizer and tillage was studied. Despite the very intensive pruning regime (five prunings/year) for a six-year period, the leucaena hedgerows continue to produce substantial amounts of prunings, nitrogen yield and stakes. Application of nitrogen to the maize crop increased dry matter and nitrogen yield from the leucaena prunings. Although high nitrogen yield was obtained from the prunings, the application of low nitrogen rates was still needed for obtaining a high maize yield. Maize grain yield can be sustained at about 2.0 t/ha with continuous application of leucacna prunings only. Without application of leucaena prunings and nitrogen maize yield continued to decline with subsequent croppings. Cowpea grain yield was not affected either by leucaena prunings or by residual nitrogen. Tillage (rototilling) resulted in either higher or the same maize and cowpea yields as compared with no-tillage. Application of leucaena prunings resulted in higher soil moisture retention, organic matter, exchangeable K, Ca, Mg, and also nitrate levels in the soil solution. Leucaena and maize appear to extract soil moisture from different zones in the soil. Timely pruning of hedgerows is necessary to minimize shading.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied climatology 37 (1986), S. 233-240 
    ISSN: 1434-4483
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Zusammenfassung Diese Untersuchung behandelt den Tauabsatz einer tropischen Station. Die Bedeutung des Taus kann nicht überbetont werden, besonders in der Trockenzeit, wenn die Pflanzen unter starkem Wasserstress stehen. Es fand sich ein positiver Zusammenhang zum Niederschlag. Im Tagesgang liegt das Maximum der Taubildung zwischen 6 und 8 Uhr, was einen steuernden Prozeß zugrunde liegen haben dürfte. In der Trockenzeit beginnt die Taubildung später als in der Regenzeit. Die schon von Ireland hervorgehobene Anomalie im August mit deutlich geringeren Werten zeigte sich auch hier.
    Notes: Summary This study presents the results of an analysis of the dewfall features of a tropical station. The importance of dewfall cannot be overemphasized, especially during the dry season when plants are under seriously stress. A positive correlation was found between dewfall and rainfall. Dew formation was found to peak on a diurnal basis between 6 a.m. to 8 a.m., suggesting that some steering mechanism is required for dew formation at this station. Dew formation starts later at night during the dry season but much earlier during the rainy season. The August anomaly already highlighted by Ireland showed up in dew formation as there was a marked reduction in dew formation in that month.
    Type of Medium: Electronic Resource
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