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91.
A model to project forest growth in the Terra Firme forests of the eastern Amazon is described. It is based on 12–17 years measurements from experimental plots at Jarí and Tapajós. Forest stands are represented by cohorts of species group, diameter, and defect. There are 54 species groups, with a robust diameter increment function fitted to each, tables of mortality by crown and defect status, and recruit lists by disturbance level and locality. Stand level functions partition trees by crown status, and modify growth for stand density. Recruitment is a function of basal-area losses. Evaluation compares model performance with two experiments involving heavy felling in Tapajos State Forest. At one site, total bole volume growth of all species over 45 cm DBH was 2.56 m3 ha−1 year−1 over 17 years, whereas the model projected 3.13 m3 ha−1 year−1. At the other site, actual growth over 12 years was 0.39 m3 ha−1 year−1, with the model giving an identical result. Both felled and control plots are compared in the study and accurately simulated. Some weaknesses in the model are discussed. 相似文献
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Assessment of method reliability and determination of reference intervals for rotational thromboelastometry in horses
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M-C Bartens M Drillich K Rychli M Iwersen T Arnholdt L Meyer 《New Zealand veterinary journal》2016,64(5):263-267
AIMS: To evaluate two different hydrometers and an optical and a digital Brix refractometer for the assessment of bovine colostrum quality, in terms of accuracy and precision compared with the measurement of IgG concentrations using radial immunodiffusion (RID), and to evaluate the reliability and repeatability of the Brix refractometers.METHODS: To determine reliability and repeatability, 145 colostrum samples were tested by two independent observers twice, using the optical and digital Brix refractometers. A further 193 colostrum samples from Holstein cows were collected on one commercial dairy farm at first milking and tested with two hydrometers and an optical and digital Brix refractometer. An aliquot of each sample was frozen for RID measurement of IgG concentrations and samples were classified as poor (≤50 g IgG/L) or good (>50?g?IgG/L) quality colostrum. Intraclass correlation coefficients (ICC) were used to determine inter- and intra-observer reliability and repeatability. Optimised cut-off values for the four devices were determined using receiver operating characteristics (ROC) analysis with the RID results as the reference. Using these cut-offs, sensitivities and specificities for determining good quality colostrum were calculated.RESULTS: The ICC for inter-observer reliability was 0.98 for the optical Brix refractometer, and for intra-observer repeatability was 0.97 and 0.98 for the optical and the digital Brix refractometers, respectively. For the 193 colostrum samples, 67 (34.7%) had concentrations of IgG ≤50 g/L determined by RID. Optimised cut-off values evaluated by ROC analysis were higher for all devices compared with manufacturer reference or previously published values. Using these values, the sensitivities for the two hydrometers, and the optical and the digital Brix refractometers were 0.73, 0.71, 0.56 and 0.79, respectively; specificities were 0.72, 0.61, 0.90 and 0.69, respectively.CONCLUSIONS AND CLINICAL RELEVANCE: The Brix refractometers provided the most accurate assessment of colostrum quality of the devices evaluated, and demonstrated excellent precision in terms of repeatability. To provide optimal health for newborn calves, a sufficient intake of good quality colostrum is essential. The Brix refractometers provide rapid, convenient tools for classification of colostrum quality. 相似文献
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遮阴对红松幼苗生长及光合特性的影响 总被引:6,自引:0,他引:6
在辽宁省草河口镇辽宁省森林经营研究所试验苗圃,采用遮阴棚设置,与全光(100%,对照区)对照,研究透光75%(A区)、透光40%(B区)、透光10%(C区)光照强度下对红松幼苗的生长及光合生理变化情况.结果表明:红松1a苗高、根长都以对照区的为最高,第三年的苗高、根长、当年高生长都以A区的为最大.两次测量各处理区地径生长,经方差分析有显著差异.而两年测量的生物量都以A区的为最大.光合速率日变化中,对照区出现"双峰"曲线,其他处理区都是"单峰"曲线.蒸腾速率的日变化与光合速率的日变化趋势一致.各处理区的平均光合速率的排序与生物量的排序相同,顺序为:A区>对照区>B区>C区,表明播种红松幼苗有一定的耐阴性,适当的遮阴有利于幼苗的生长. 相似文献
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《The Journal of Applied Poultry Research》2017,26(2):219-225
Samples of pelleted feed may be taken during manufacturing and analyzed for nutrient content in order to estimate if nutrients are in accordance with diet formulation. The objective of this study was to determine the impact of mix time, sample location, sample number, and sample blending technique on analyzed nutrients. Ingredients were mixed in a single screw vertical mixer for 30 s or 10 minutes. Samples were taken post extrusion from the pellet die as hot pellets or post cooling and conveyance as finished feed. Two or 10 samples were collected at equally spaced time intervals and pooled. Subsamples were obtained by blending pooled samples by hand or using a sample splitting device. Proximate and supplemental amino acid analysis was determined on each blended subsample and standardized for moisture content. Crude fat and free supplemental DL-methionine were affected by mix time (P < 0.05). The 10-minute mix time produced crude fat and free supplemental DL-methionine that had lower and higher values, respectively, compared to the 30-second mix time and agreed more with the calculated nutrient profile and diet formulation. Free supplemental DL-methionine was also affected by sampling location (P < 0.05). Samples obtained at the pellet die were higher and agreed more with diet formulation compared to finished feed samples. Analysis of free supplemental DL-methionine from samples obtained at the pellet die may best indicate pelleted diet homogeneity and validate the diet formulation. 相似文献