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排序方式: 共有433条查询结果,搜索用时 31 毫秒
81.
Nicholas Clarke Silje Skår O. Janne Kjønaas Kjersti Holt Hanssen Tonje Økland Jørn-Frode Nordbakken 《Scandinavian Journal of Forest Research》2018,33(3):299-307
Short-term (three to four years) effects of forest harvesting on soil solution chemistry were investigated at two Norway spruce sites in southern Norway, differing in precipitation amount and topography. Experimental plots were either harvested conventionally (stem-only harvesting, SOH) or whole trees, including crowns, twigs and branches were removed (whole-tree harvesting, WTH), leaving residue piles on the ground for some months before removal. The WTH treatment had two sub-treatments: WTH-pile where there had been piles and WTH-removal, from where residues had been removed to make piles. Increased soil solution concentrations of NO3–N, total N, Ca, Mg and K at 30?cm depth, shown by peaks in concentrations in the years after harvesting, were found at the drier, less steep site in eastern Norway after SOH and WTH-pile, but less so after WTH-removal. At the wetter, steeper site in western Norway, peaks were often observed also at WTH-removal plots, which might reflect within-site differences in water pathways due largely to site topography. 相似文献
82.
A NOVEL,REMOVABLE, CERROBEND,BEAM‐BLOCKING DEVICE FOR RADIATION THERAPY OF THE CANINE HEAD AND NECK: PILOT STUDY
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Michael S. Kent Davide Berlato Isabelle Vanhaezebrouck Ira K. Gordon Katherine S. Hansen Alain P. Theon Randall W. Holt Earl A. Trestrail 《Veterinary radiology & ultrasound》2017,58(1):100-105
Radiation therapy of the head and neck can result in mucositis and other acute affects in the oral cavity. This prospective pilot study evaluated a novel, intraoral, beam‐blocking device for use during imaging and therapeutic procedures. The beam‐blocking device was made from a metal alloy inserted into a coated frozen dessert mold (Popsicle® Mold, Cost Plus World Market, Oakland, CA). The device was designed so that it could be inserted into an outer shell, which in turn allowed it to be placed or removed depending on the need due to beam configuration. A Farmer type ionization chamber and virtual water phantom were used to assess effects of field size on transmission. Six large breed cadaver dogs, donated by the owner after death, were recruited for the study. Delivered dose at the dorsal and ventral surfaces of the device, with and without the alloy block in place, were measured using radiochromic film. It was determined that transmission was field size dependent with larger field sizes leading to decreased attenuation of the beam, likely secondary to scatter. The mean and median transmission on the ventral surface without the beam‐blocking device was 0.94 [range 0.94–0.96]. The mean and median transmission with the beam‐blocking device was 0.52 [range 0.50–0.57]. The mean and median increase in dose due to backscatter on the dorsal surface of the beam‐blocking device was 0.04 [range 0.02–0.04]. Findings indicated that this novel device can help attenuate radiation dose ventral to the block in dogs, with minimal backscatter. 相似文献
83.
A quantitative model for trade pathway analysis of plant pest entry and transfer to a host in European Union territory
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J. Holt A. W. Leach A. MacLeod D. Tomlinson M. Christodoulou J. D. Mumford 《EPPO Bulletin》2017,47(2):220-226
A quantitative pathway model, QPAFood, has been designed to support risk assessment for plant pest entry into European Union (EU) territory on a range of edible plant commodities via trade flows. The model calculates the distribution of an imported infested/infected commodity along a pathway into and within the EU from source countries, based on Eurostat data and other data/information. The model determines the implications of global trade pathways for the potential arrival of the infested commodity in the EU28 Member States. Within each Member State, the calculation proceeds by distributing the commodity according to uses, notably retail or processing, to the vulnerable area of commercial host crops determined in each NUTS2 region and then quantifies the consequent potential for pest–host contact which could lead to pest transfer. Annual and monthly estimates of contact risk are tabulated and visualized for Member States and NUTS2 regions. The model was developed originally for the European Food Safety Authority using four case studies of specific pest–commodity combinations. These pests had relatively limited host ranges and the model has now been extended in the context of the EC FP7 DROPSA project for the multiple commodity pathways associated with the highly polyphagous fruit pest Drosophila suzukii. 相似文献
84.
Colin F Quinn John L Freeman Ray JB Reynolds Jennifer J Cappa Sirine C Fakra Matthew A Marcus Stormy D Lindblom Erin K Quinn Lindsay E Bennett Elizabeth AH Pilon-Smits 《BMC ecology》2010,10(1):19
Background
Hyperaccumulation, the rare capacity of certain plant species to accumulate toxic trace elements to levels several orders of magnitude higher than other species growing on the same site, is thought to be an elemental defense mechanism against herbivores and pathogens. Previous research has shown that selenium (Se) hyperaccumulation protects plants from a variety of herbivores and pathogens. Selenium hyperaccumulating plants sequester Se in discrete locations in the leaf periphery, making them potentially more susceptible to some herbivore feeding modes than others. In this study we investigate the protective function of Se in the Se hyperaccumulators Stanleya pinnata and Astragalus bisulcatus against two cell disrupting herbivores, the western flower thrips (Frankliniella occidentalis) and the two-spotted spider mite (Tetranychus urticae). 相似文献85.
86.
Mithril C Dragsted LO Meyer C Blauert E Holt MK Astrup A 《Public health nutrition》2012,15(10):1941-1947
87.
DM Magalhães DD Fernandes MBS Mororó CMG Silva GQ Rodrigues JB Bruno MHT Matos CC Campello JR Figueiredo 《Reproduction in domestic animals》2011,46(1):134-140
The aim of the present study was to evaluate the effects of different medium replacement intervals on the viability, antral cavity formation, growth and in vitro maturation (IVM) of oocytes from caprine and ovine pre‐antral follicles. Pre‐antral ovarian follicles (≥150 μm) were isolated from the ovarian cortex of goats and sheep and were individually cultured for 24 days using two different medium replacement intervals [2 days (T1) or 6 days (T2)]. Follicle development was evaluated on the basis of antral cavity formation, increases in follicular diameter and the presence of healthy cumulus oocyte complexes and fully grown oocytes. For caprine species, results showed a higher percentage (p < 0.05) of viable follicles in T1 than T2 from day 6 until the end of the culture. In addition, when comparing both treatments after the same culture duration, the rate of antrum formation was significantly higher in T1 than in T2 from day 12 onwards. Yet, in ovines, when both treatments were compared on day 24 of the culture, there were more viable follicles in T2 than in T1 (p < 0.05). In the caprine species, percentages of fully grown oocytes (≥110 μm) acceptable for IVM after 24 days of culture were significantly higher in normal follicles cultured in T1 (30.0%) than in T2 (6.7%; p < 0.05). On the other hand, in ovines, at the end of the culture, the percentage of oocytes destined for IVM was higher in T2 than in T1 (23.5% vs 2.9%; p < 0.05). In conclusion, under the same conditions, the frequency of medium replacement significantly affected the in vitro development of caprine and ovine pre‐antral follicles. To improve the efficiency of the culture system, the medium must be replaced every 2 and 6 days for goat and sheep pre‐antral follicles, respectively. 相似文献
88.
Objective: To describe preoperative use of skin stretchers to elongate a peninsular thoracodorsal axial pattern flap to close a large antebrachial wound on a dog. Study Design: Case report. Animals: A 21 kg, 7‐year‐old, male intact mixed breed dog. Methods: Two skin stretchers were applied to the site of the thoracodorsal axial pattern flap 4 days before surgery. The elastic cables connecting the adhesive pads were tightened daily to increase the skin available for a peninsular thoracodorsal axial pattern flap, which was created and rotated 180° to cover an antebrachial defect to a level 2 cm proximal to the carpus. Results: The entire flap survived; there was a small amount of incisional separation at the distal margin of the flap that healed without further treatment. Conclusion: Preoperative skin stretching provided additional skin for the axial pattern flap used. 相似文献
89.
90.