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111.
Toona ciliata Roem. (Australian red cedar) requires a nurse-tree overstory to prevent damage from drought and irradiation in some regions of north-eastern Argentina. T. ciliata was planted in the understory of Pinus taeda L. (625 stems/ha), Pinus elliottii Engelm. × Pinus caribaea Morelet (625 stems/ha), and Grevillea robusta A. Cunn. (833 stems/ha) nurse trees, which were thinned to 0, 25, 50, 75 and 100% of the initial densities. We measured initial T. ciliata mortality and growth as well as Leaf Area Index (LAI) based on light transmission. T. ciliata soil water availability and its effect on early growth and mortality were examined by modelling drought stress using the two-dimensional forest hydrology model ForWaDy. Simulated patterns in T. ciliata water stress for the different overstory treatments were consistent with observed patterns of mortality. Early mortality was lowest with a G. robusta overstory, with corresponding lowest drought stress values and high modelled soil water contents in the top soil layer in intermediate and high overstory densities. Mortality was highest with a P. elliottii × P. caribaea overstory in treatments with the highest modelled drought stress values in the most open treatments. The model supported our field observations by indicating that water stress was an important limitation to T. ciliata survival and growth on our study sites. The linkage between T. ciliata establishment success, early growth and soil water availability as indicated by ForWaDy, leads us to conclude that the model is a suitable stand management tool for guiding establishment of T. ciliata plantations. 相似文献
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Karim D. Kalache Roberto Romero Giancarlo Conoscenti Faisal Qureshi Suzanne M. Jacques Tinnakorn Chaiworapongsa Marjorie Treadwell Anthony Johnson 《黑龙江环境通报》2003,23(2):108-110
A case of dilated coronary sinus with persistent left superior vena cava diagnosed at 33 weeks in a fetus with trisomy 18 is reported. The features of this cardiac anomaly on prenatal ultrasonography and its association with trisomy 18 are discussed. Published in 2003 John Wiley & Sons, Ltd. 相似文献
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Heather Henson-Ramsey Jay Levine Suzanne Kennedy-Stoskopf Sharon K. Taylor Damian Shea Michael K. Stoskopf 《Environmental Modeling and Assessment》2009,14(3):411-418
A simple and dynamic pharmacokinetic model was developed to predict bioconcentration of organic contaminants in earthworms.
The model was parameterized experimentally by placing Lumbricus terrestris in soil contaminated with 200 μg/cm2 of malathion. The toxicokinetics of malathion uptake, depuration, and degradation in soil is measured. After parameterization,
the model was able to accurately predict the bioconcentration factor of malathion at steady state. Sensitivity analyses were
performed and the rate of absorption was determined to be the most sensitive parameter. Varying the rate of malathion elimination
from earthworm tissues, malathion degradation, and the amount of malathion applied to the soil by 25-fold did not result in
the bioconcentration of malathion. An increase in the rate of malathion absorption into earthworm tissues by 25-fold did result
in bioconcentration. Previously published pharmacokinetic studies on xenobiotics with log K
ow values ranging up to 8.05 were used to test the predictive capacity of the model. The model was able to predict from 83%
to 105% of the experimentally derived bioconcentration factors. 相似文献
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Laurent Guibaud 《黑龙江环境通报》2009,29(4):420-433
More than 20 years after its introduction, magnetic resonance imaging (MRI) is now considered a useful complementary tool in the imaging work-up of fetal brain structural anomalies, but its real contribution in neuro-fetal imaging is still controversial. Our purpose is to present an overview of the most valuable indications of fetal cerebral MRI in current practice as guided by dedicated ultrasound analysis. On the basis of a review of the literature and our personal experience, we underline herein the real complementarities between these two techniques in different clinical or imaging settings and show how MRI adds significant information compared with ultrasound, especially in the late second and third trimesters. We assess the interest of using MRI from a technical point of view (complete and extensive anatomical analysis, analysis of developmental and pathological processes) and from a practical point of view in different imaging and clinical settings. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献