Home About us Contact
|
Home About us Contact | ||
|
|
||
Similar Depth (similar + depth)
Selected AbstractsThe influence of sward canopy structure on foraging decisions by grazing cattle.GRASS & FORAGE SCIENCE, Issue 2 2003Abstract Patch selection by grazing dairy cows in response to simultaneous variation in combinations of sward structural characteristics was examined in three experiments in which four mature dairy cows were offered a choice of patches (typically 0.9 m × 0.9 m) of perennial ryegrass (Lolium perenne) presented in a linear arrangement. Treatments involved combinations of variations in sward height, stubble height and/or depth of regrowth, prepared by preliminary cutting treatments. They were arranged in balanced sets of four to nine treatments, which were arranged in linear sequences of eighteen to twenty-seven patches. Within experiments, sequences were balanced across replicate sets of patches, which were grazed separately by individual cows. The number of bites removed and the residence time for each patch were highly correlated in all three experiments, and the results are reported using number of bites per patch as an estimator of foraging behaviour. In the first experiment, with vegetative swards, cows preferentially selected the tallest swards. When swards comprising reproductive stem were offered in Experiment 2, cows selectively grazed short-stubble swards rather than tall-stubble swards, although both offered a similar depth of regrowth. Cows did not exhibit preference for swards comprising the greatest quantity of leaf mass, indicating that the spatial distribution of plant components assumed greater importance. In the third experiment, the number of bites removed increased with increasing depth of regrowth, and was negatively correlated with sward height. The three patch-appraisal cues investigated were broadly ranked in order of importance as (i) depth of regrowth, (ii) sward maturity and (iii) sward height. There was no evidence, at least at a short temporal scale, that patch behaviour was influenced by conditions in adjacent patches, suggesting that the cows assessed grazing opportunities on a patch-by-patch basis. [source] How Historians Begin: Openings in Historical DiscourseHISTORY, Issue 320 2010TREVOR DEAN Why is the problem of beginning , much discussed in literary scholarship , not dealt with in similar depth by historians? This article attempts an answer to this question, and does so in three ways. First, it examines literary scholarship on textual openings, showing the various ways in which the beginning is given significance. Then, it examines and challenges the common presentation of historical discourse as distinct from fiction. Finally, it examines two sets of data: the openings of 100 historical monographs are analysed for their ,fictionality', and the openings of 200 research articles are analysed for their rhetorical structures. [source] Diving in shallow water: the foraging ecology of darters (Aves: Anhingidae)JOURNAL OF AVIAN BIOLOGY, Issue 4 2007Peter G. Ryan Diving birds have to overcome buoyancy, especially when diving in shallow water. Darters and anhingas (Anhingidae) are specialist shallow-water divers, with adaptations for reducing their buoyancy. Compared to closely-related cormorants (Phalacrocoracidae), darters have fully wettable plumage, smaller air sacs and denser bones. A previous study of darter diving behaviour reported no relationship between dive duration and water depth, contrary to optimal dive models. In this study I provide more extensive observations of African darters Anhinga melanogaster rufa diving in water<5 m deep at two sites. Dive duration increases with water depth at both sites, but the relationship is weak. Dives were longer than dives by cormorants in water of similar depth (max 108 s in water 2.5 m deep), with dives of up to 68 s observed in water<0.5 m deep. Initial dives in a bout were shorter than expected, possibly because their plumage was not fully saturated. Dive efficiency (dive:rest ratio) was 5,6, greater than cormorants (2.7±0.4 for 18 species) and other families of diving birds (average 0.2,4.3). Post-dive recovery periods increased with dive duration, but only slowly, resulting in a strong increase in efficiency with dive duration. All dives are likely to fall within the theoretical anaerobic dive limit. Foraging bouts were short (17.8±4.3 min) compared to cormorants, with birds spending 80±5% of time underwater. Darters take advantage of their low buoyancy to forage efficiently in shallow water, and their slow, stealthy dives are qualitatively different from those of other diving birds. However, they are forced to limit the duration of foraging bouts by increased thermoregulatory costs associated with wettable plumage. [source] Bilaminar techniques for the treatment of recession-type defects.JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 10 2003A comparative clinical study Abstract Objectives: Complete root coverage is the primary objective to be accomplished when treating gingival recessions in patients with aesthetic demands. Furthermore, in order to satisfy patient demands fully, root coverage should be accomplished by soft tissue, the thickness and colour of which should not be distinguishable from those of adjacent soft tissue. The aim of the present split-mouth study was to compare the treatment outcome of two surgical approaches of the bilaminar procedure in terms of (i) root coverage and (ii) aesthetic appearance of the surgically treated sites. Material and Methods: Fifteen young systemically and periodontally healthy subjects with two recession-type defects of similar depth affecting contralateral teeth in the aesthetic zone of the maxilla were enrolled in the study. All recessions fall into Miller class I or II. Randomization for test and control treatment was performed by coin toss immediately prior to surgery. All defects were treated with a bilaminar surgical technique: differences between test and control sites resided in the size, thickness and positioning of the connective tissue graft. The clinical re-evaluation was made 1 year after surgery. Results: The two bilaminar techniques resulted in a high percentage of root coverage (97.3% in the test and 94.7% in the control group) and complete root coverage (gingival margin at the cemento-enamel junction (CEJ)) (86.7% in the test and 80% in the control teeth), with no statistically significant difference between them. Conversely, better aesthetic outcome and post-operative course were indicated by the patients for test compared to control sites. Conclusions: The proposed modification of the bilaminar technique improved the aesthetic outcome. The reduced size and minimal thickness of connective tissue graft, together with its positioning apical to the CEJ, facilitated graft coverage by means of the coronally advanced flap. Zusammenfassung Hintergrund: Die vollständige Deckung der Wurzeloberfläche ist das primäre Ziel, das bei der Therapie von fazialen Rezessionen bei Patienten mit ästhetischen Ansprüchen erreicht werden soll. Weiterhin sollte die Rezessionsdeckung, wenn sie den Ansprüchen des Patienten vollends entsprechen soll, mit einer Dicke und Farbe der Gingiva erreicht werden, die nicht vom benachbarten Gewebe zu unterscheiden sind. Zielsetzung: Vergleich der Therapieergebnisse von 2 chirurgischen Varianten der zweischichtigen Technik im Halbseitenversuch hinsichtlich (1) Rezessionsdeckung und (2) ästhetischer Erscheinung der chirurgisch behandelten Stellen. Material und Methoden: 15 junge und parodontal gesunde Personen mit jeweils 2 Rezessionsdefekten ähnlicher Größe an kontralateralen Zähnen im ästhetischen Bereich des Oberkiefers wurden in die Studie aufgenommen. Alle Rezessionen gehörten in die Miller-Klassen I oder II. Die Randomisierung für die Test- und Kontrollbehandlung erfolgte unmittelbar präoperativ durch Münzwurf. Alle Defekte wurden nach einer zweischichtigen chirurgischen Technik behandelt: Die Unterschiede zwischen Test- und Kontrollstellen bestanden in Größe, Dicke und Positionierung des Bindegewebstransplantates. Die klinische Nachuntersuchung erfolgte 1 Jahr postoperativ. Ergebnisse: Beide zweischichtigen Techniken führten zu einem hohen Prozentsatz von Wurzeldeckung (Test: 97,3%; Kontrolle: 94,7%) und kompletter Wurzeldeckung (Gingivarand an der Schmelz-Zement-Grenze [SZG]) (Test: 86,7%; Kontrolle: 80%) ohne statistisch signifikante Unterschiede zwischen beiden Gruppen. Allerdings wurden mit der Testtherapie bessere ästhetische Ergebnisse erzielt als mit der Kontrollbehandlung. Schlussfolgerung: Die vorgestellte Modifikation der zweischichtigen Technik verbesserte die ästhetischen Ergebnisse. Die reduzierte Größe und minimale Dicke des Bindegewebstransplantates zusammen mit seiner Positionierung apikal der SZG erleichterten eine Deckung mittels eines koronalen Verschiebelappens. Résumé Objectif: Un recouvrement complet de la racine est le premier objectif lorsque l'on traite des récessions gingivales chez les patients ayant une demande esthétique. De plus, afin de satisfaire totalement la demande du patient, cette couverture radiculaire doit aussi être réalisé par des tissus mous de couleur et d'épaisseur qui ne se distinguent pas des tissus mous adjacents. Le but de cette étude en bouche séparée était de comparer le devenir de deux approches chirurgicales de la technique bilaminaire pour (i) le recouvrement de la racine et (ii) l'apparence esthétique des sites traités chirurgicalement. Matériel et Méthodes: 15 sujets jeunes et indemnes de maladie parodontale et systèmique présentant deux récessions de profondeur similaires sur des dents contralatérales dans des zones esthétiques du maxillaire furent enrollés dans cette étude. Toutes les récessions étaient des classes I ou II de Miller. La répartition pour les traitements test ou contrôle fut tirée à pile ou face juste avant la chirurgie. Toutes les lésions furent traitées par la technique bilaminaire, la différence entre les groupes résidant dans la taille, l'épaisseur et le positionnement du greffon de tissus conjonctif. La réévaluation clinique fut faite un an après la chirurgie. Résultats: Les deux techniques bilaminaires ont entrainé un fort pourcentage de recouvrement radiculaire (97.3% pour le groupe test et 94.7% pour le groupe contrôle) et le recouvrement complet (gencive marginale au niveau de la CEJ) (86.7% dans le groupe test et 80% pour le groupe contrôle) sans différence statistiquement significative entre elles. Par contre, un meilleur rendu esthétique et suites post opératoires furent rapportés par les patients pour le traitement test. Conclusions: La modification proposée de cette technique bilaminaire améliore le devenir esthétique. La taille réduite et l'épaisseur minimale greffon conjonctif et son positionnement apical au CEJ, ont facilité le recouvrement du greffon par le lambeau déplacé coronairement. [source] The effects of water table draw-down (as a surrogate for climate change) on the hydrology of a fen peatland, CanadaHYDROLOGICAL PROCESSES, Issue 17 2006Peter N. Whittington Abstract Hydrological response to climate change may alter the biogeochemical role that peatlands play in the global climate system, so an understanding of the nature and magnitude of this response is important. In 2002, the water table in a fen peatland near Quebec City was lowered by ,20 cm (Experimental site), and hydrological response was measured compared to Control (no manipulation) and Drained (previously drained c. 1994) sites. Because of the draw-down, the surface in the Experimental pool decreased 5, 15 and 20 cm in the ridge, lawn and mat, respectively, increasing bulk density by ,60% in the Experimental lawn. Hydraulic conductivity (K) generally decreased with depth and from Control (25,125 cm) 10,1 to 10,5 cm s,1 to Experimental (25,125 cm) 10,2 to 10,7 cm s,1 and to Drained (25,75 cm) 10,2 to 10,6 cm s,1. In similar topographic locations (ridge, lawn, mat), K trended Control > Experimental > Drained, usually by an order of magnitude at similar depths in similar topographic locations. Water table fluctuations in the Drained site averaged twice those of the Control site. The water table in the Control lawn remained at a stable depth relative to the surface (,, 1 cm) because the lawn peat floats with changes in water table position. However, the Drained lawn peat was more rigid because of the denser degraded peat, forcing the water to fluctuate relative to the surface and further enhancing peat decay and densification. This provides a positive feedback loop that could intensify further peat degradation, changing the carbon cycling dynamics. Copyright © 2006 John Wiley & Sons, Ltd. [source] The Tertiary collision-related thermal history of the NW HimalayaJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2002G. Foster Abstract Garnet-whole rock Sm-Nd data are presented for several samples from the Indian plate in the NW Himalaya. These dates, when combined with the P-T evolution of the Indian plate rocks, allow a thorough reconstruction of the prograde thermal evolution of this region (including the Nanga Parbat Haramosh Massif) during the early Cenozoic. Combining these data with Rb-Sr mineral separate ages, enables us to constrain the post-peak cooling history of this region of the Himalaya. The data presented here indicate that the upper structural levels of the cover rocks of the Nanga Parbat Haramosh Massif, and similar rocks in the Kaghan Valley to the south-west, were buried to pressures of c. 10 kbar and heated to temperatures of c. 650 °C at 46,41 Ma. The burial of the lower structural levels of the cover rocks of the Nanga Parbat Haramosh Massif, to similar depths but at higher temperatures of c. 700 °C, occurred slightly later at 40,36 Ma, synchronous with the imbrication and exhumation of the amphibolite- and eclogite-grade rocks of the Kaghan Valley. In contrast, the cover rocks of the Nanga Parbat Haramosh Massif were not imbricated or exhumed at this time, remaining buried beneath the Kohistan-Ladakh Island Arc until the syntaxis-forming event that occurred in the last 10 Myr. The timing of tectonic events in the north-western Himalaya differs from that experienced by the rocks of the Central Himalaya in that the earliest stage of burial in the NW Himalaya predates that of the Central Himalaya by c. 6 Myr. This difference may result from the diachronous nature of the Indo-Asian collision or may simply be a reflection of differing timing at different structural levels. [source] Thermoluminescence sensitivity and thermal history of type 3 ordinary chondrites: Eleven new type 3.0,3.1 chondrites and possible explanations for differences among H, L, and LL chondritesMETEORITICS & PLANETARY SCIENCE, Issue 6 2002P. H. Benoit We have identified 11 UOCs of petrologic types 3.0,3.1: Adrar 003, Elephant Moraine (EET) 90066, EET 90161, Grosvenor Mountains (GRO) 95502, Lewis Cliff (LEW) 88477, Meteorite Hills (MET) 96503, Yamato (Y)-790787, Y-791324, Y-791558, Y-793565, and Y-793596. These samples represent an important new resource for researchers interested in the nature of primitive solar system materials. Previously reported trends in which TL sensitivity increases with TL peak temperature and TL peak width, which we interpret in terms of crystallization of feldspar in the ordered or disordered forms during metamorphism, are confirmed by the new data. Importantly, the present data strengthen the trend described earlier in which the mean level of metamorphism experienced by UOCs increases along the series LL, L and H. This suggests either different burial depths for the UOCs from each class, or formation at similar depths in regoliths of different thickness. [source] | ||||||||||