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Ground Contact (ground + contact)
Selected AbstractsEvaluation of laboratory assays for the assessment of leaching of copper and chromium from ground-contact woodENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2007Ana I. García-Valcárcel Abstract Laboratory studies were conducted to assess the leaching of Cu and Cr from wood, treated with a Cu-Cr-B preservative, when placed in contact with soil. Two laboratory assays were performed: Wood in contact with soil solutions over 30 d, and wood in direct contact with soil over 30 weeks. The influence of several factors, such as soil type and fertilizer use, was studied in both assays. In addition, the effect of soil moisture content and temperature was evaluated when wood was in contact with soil. A discrepancy in the results of the laboratory assays was observed. Leaching of Cu and Cr increased when soil in contact with wood was fertilized, but only an increase of Cu leaching was observed when soil solutions from fertilized soils were used. Moreover, soil solutions from a sandy clay loam soil produced a higher Cu leaching than those from a loamy sand soil, whereas the contrary occurred when treated wood was in direct contact with these soils. In the assay of treated wood in ground contact, the highest metal losses were produced in fertilized soils maintained at constant temperature and high soil moisture content, the latter being the most important factor. These losses were in the range of 5.34 to 15.6% for Cu and 1.85 to 2.35% for Cr in the soils studied. The proposed laboratory assay, using treated wood in direct contact with soil at a moisture content near field capacity during a period of 30 weeks, produced total metal losses that were in accordance with those reported by other authors under field conditions, expressed on a per-year basis. [source] Time domain characteristics of hoof-ground interaction at the onset of stance phaseEQUINE VETERINARY JOURNAL, Issue 7 2006J. F. BURN Summary Reasons for performing study: Little is known about the interaction of the hoof with the ground at the onset of stance phase although is it widely believed that high power collisions are involved in the aetiopathology of several conditions causing lameness. Objectives: To answer 3 questions regarding the fundamental nature of hoof-ground collision: (1) is the collision process deterministic for ground surfaces that present a consistent mechanical interface (2) do collision forces act on the hoof in a small or large range of directions and (3) Is the hoof decelerated to near-zero velocity by the initial deceleration peak following ground contact? Methods: Hoof acceleration during the onset of stance phase was recorded using biaxial accelerometry for horses trotting on a tarmac surface and on a sand surface. Characteristics of the collision process were identified both from vector plots and time series representations of hoof acceleration, velocity and displacement. Results: The response of the hoof to collision with smooth tarmac was predominantly deterministic and consistent with the response of a spring-damper system following shock excitation. The response to collision with sand was predominantly random. The deceleration peak following ground contact did not decelerate the hoof to near-zero velocity on tarmac but appeared to on sand. On both surfaces, collision forces acted on the hoof in a wide range of directions. Conclusions: The study suggests the presence of stiff, visco-elastic structures within the foot that may act as shock absorbers isolating the limb from large collision forces. Potential relevance: The study indicates objectives for future in vivo and in vitro research into the shock absorbing mechanism within the equine foot; and the effects of shoe type and track surface properties on the collision forces experienced during locomotion. Studies of this nature should help to establish a link between musculoskeletal injury, hoof function and hoof-ground interaction if, indeed, one exists. [source] Occurrence of Heterobasidion basidiocarps on cull pieces of Norway spruce left on cutting areas and in mature spruce standsFOREST PATHOLOGY, Issue 6 2007M. M. Müller Summary Fruiting of Heterobasidion on cull pieces and stumps of Norway spruce was investigated in cutting areas and mature spruce stands located in southern Finland. Cull pieces of variable size and showing butt rot were left on three clear-cut areas and in one thinned stand. Additionally, a part of the cull pieces was transported to mature forest sites with closed canopy. During the succeeding 3,4 years the cull pieces were investigated annually for sporocarps of Heterobasidion, and the area of actively sporulating pore layer of each sporocarp was measured. Root bases of spruce stumps in the logging areas were excavated and sporocarps found on the stumps also measured. At the onset of the experiment, Heterobasidion spp. were isolated from 76% of the cull pieces showing butt rot; 85% of the isolates were identified as H. parviporum and 15% as H. annosum s.s. During the following 3,4 years sporocarps were found on 20% of the 1938 cull pieces where Heterobasidion butt rot was initially detected visually. Sporocarp formation was promoted by advancement of butt rot, increasing cull piece diameter and end-to-end ground contact, but restricted by the colonization of the cull piece by Stereum sanguinolentum. Between-site differences were significant but could not be explained by differences in tree cover. At the end of the investigation period the average sporulating area of Heterobasidion sporocarp per metre of cull piece was higher than the average sporulating area per stump at three of four logging sites. Hence, leaving cull pieces containing Heterobasidion butt rot at logging areas in southern Finland can considerably increase local production of Heterobasidion spores. [source] GIS in archaeology,the interface between prospection and excavationARCHAEOLOGICAL PROSPECTION, Issue 3 2004Wolfgang NeubauerArticle first published online: 12 MAY 200 Abstract Archaeological prospection and excavation have the same research objective, namely, the study of the material culture of humans. They investigate the archaeological record but are based on different physical properties and work with different resolution and instrumentation. In addition to the study of literature concerning antique discoveries and the collection and evaluation of surface finds, it is aerial archaeology and geophysical prospection that are the most suitable methods of achieving the intended goal. Aerial photographs provide the archaeologist with a large-scale overview, and digital photogrammetric evaluation provides very detailed topographic maps and orthophotographs of the archaeological structures visible on the surface. These structures appear in various forms, through contrasts in the physical properties between the structures themselves and the material that surrounds them. In geophysical prospection, the contrasts between the physical properties of the archaeological structures and the surrounding material usually can be investigated only in the near-surface or with direct ground contact. These contrasts are not directly visible, however, and must instead be measured and converted into a comprehensible visualization. The prospection methods used in the interpretation process are not significantly different from one to another. Interpretation encompasses the localization and classification of archaeological structures, the analysis of their spatial relationships, as well as the creation of models showing the main stratification at a site. Unlike excavations, through archaeological interpretation of prospection data, various accurate archaeological models of the entire site and the surrounding landscape can be made available rapidly. These models can be used for targeted excavations, so as to further condense the information and to refine the models. If all the data are made available in a geographical information system (GIS), it can be combined and further analysed by the excavator as well as by the prospector. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||