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排序方式: 共有345条查询结果,搜索用时 390 毫秒
1.
Charles George Clare Rowland France Gerard Heiko Balzter 《Remote sensing of environment》2006,104(3):346-359
The boreal forest contains almost half the total carbon pool of world forest ecosystems, and so has a very significant role in global biogeochemical cycles. The flux of greenhouse gases in and out of these forests is influenced strongly by disturbances such as diseases, logging and predominantly fire. It is important to quantify these disturbances to enable the modelling of major greenhouse gases. However, because of the remoteness and vastness of the boreal forest, little data is available on the type, extent, frequency and severity of these disturbances in Siberia. For burnt areas, two of the more responsive wavelengths are the short wave infra-red (SWIR) and the near infra-red (NIR). These produce a vegetation index, the normalised difference SWIR (NDSWIR) capable of detecting retrospective disturbances. Here we combine the NDSWIR from MODIS imagery acquired in the summer of 2003 with thermal anomaly data from 1992 to 2003 to detect and date areas which burnt at some point between 1992 and 2003. The semi-automated method is called SWIR and Thermal ANomalies for Detecting Disturbances (STANDD) and is complemented by an Normalised Difference Vegetation Index (NDVI) differencing method using MODIS 2002 and 2003 imagery to ensure reliable detection of area burnt in the year of image acquisition (i.e. 2003). The area of this study covers approximately 3 million km2 stretching from Lake Baikal in the south to the Laptev Sea in the north, above the Arctic Circle. Landsat ETM+ images were used to validate the shape and areal extent of the burnt areas resulting in an 81% overall accuracy with a kappa coefficient of agreement of 0.63. 相似文献
2.
Caroline P Leblanc France M Rioux 《Revue canadienne de la pratique et de la recherche en diététique》2007,68(4):222-225
PURPOSE: Iron deficiency anemia (IDA) during pregnancy and infancy is still common in developed countries, especially in low-income groups. We examined the prevalence of anemia and IDA in healthy low-income pregnant women participating in the Early Childhood Initiatives (ECI) program, and in their infants when they reached six months of age. METHODS: Pregnant women were recruited by nutritionists. In mothers, hemoglobin (Hb), mean corpuscular volume, and serum ferritin (SF) were measured at 36 +/- 2 weeks of gestation. In infants, Hb, mean corpuscular volume, SF, serum iron, total iron binding capacity (TIBC), and transferrin saturation (TS) were measured at six months of age. Thirty-one mother-infant pairs participated. RESULTS: Among the 31 pregnant women participating in the ECI program, six (19.4%) were anemic (Hb <110 g/L) and five (16.1%) suffered from IDA (Hb <110 g/L and SF <10 microg/L). Among infants, seven of 23 (30.4%) were anemic (Hb <110 g/L) and five of 23 (21.7%) suffered from IDA (Hb <110 g/L plus two of the following: TIBC >60 micromol/L, SF <10 microg/L, serum iron <5.3 micromol/L, TS < or = 15%). CONCLUSIONS: The prevalence of anemia in this group of low-income pregnant women is comparable to that in privileged women. The prevalence of IDA in infants is comparable to that observed in other high-risk groups. Effective strategies are needed to prevent IDA in vulnerable groups. 相似文献
3.
This study assessed the discriminative stimulus effects of (±)-ephedrine and its stereoisomers in pigeons discriminating 1.0 mg/kg of amphetamine from saline. Amphetamine, (±)-, (-)-, and (+)-ephedrine, and cocaine occasioned greater than 80% drug-key responding with the following rank order of potency: amphetamine > cocaine > (-)-ephedrine ≥ (±)-ephedrine ≥ (+)-ephedrine. Neither the α-adrenergic antagonist, phentolamine, nor the β-adrenergic antagonist, propranolol, antagonized the effects of amphetamine or (±)-ephedrine. In contrast, the dopamine receptor antagonist, haloperidol, antagonized the discriminative stimulus effects of amphetamine and (±)-ephedrine as well as those of (-)- and (+)-ephedrine. These results indicate that, like cocaine, (±)-ephedrine and its stereoisomers share discriminative stimulus effects with amphetamine. Moreover, these effects appear to be the result of increased activity in dopaminergic systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
Pons MN Potier O Pontvianne S Laurent N France X Battaglia P 《Water science and technology》2011,64(3):602-609
In order to characterize the pollution discharged into the Moselle River and some of its tributaries, spectroscopic techniques, namely UV-vis spectroscopy and synchronous fluorescence spectroscopy, have been combined. UV-visible spectra were analysed using the maximum of the second derivative at 225 nm (related to nitrates), the SUVA254 and E2/E3 indices (related to the nature of organic matter). Synchronous fluorescence spectra (delta lambda = 50 nm) presented different shapes depending upon the type of pollution. The pollution results from anthropogenic activities: untreated domestic sewage due to misconnections in a periurban river, effluent from urban WWTPS, agricultural runoff (nitrates) in several streams, discharge from a paper mill (humic-like substances due to wood processing) and from steel mills (PAHs). 相似文献
5.
6.
Models@ run.time 总被引:2,自引:0,他引:2
Runtime adaptation mechanisms that leverage software models extend the applicability of model-driven engineering techniques to the runtime environment. Contemporary mission-critical software systems are often expected to safely adapt to changes in their execution environment. Given the critical roles these systems play, it is often inconvenient to take them offline to adapt their functionality. Consequently, these systems are required, when feasible, to adapt their behavior at runtime with little or no human intervention. A promising approach to managing complexity in runtime environments is to develop adaptation mechanisms that leverage software models, referred to as models@run. time. Work on models@run.time seeks to extend the applicability of models produced in model-driven engineering (MDE) approaches to the runtime environment. Models@run. time is a causally connected self-representation of the associated system that emphasizes the structure, behavior, or goals of the system from a problem space perspective. 相似文献
7.
Dos Santos A Thiers V Sar S Derian N Bensalem N Yilmaz F Bralet MP Ducot B Bréchot C Demaugre F 《Proteomics. Clinical applications》2007,1(6):545-554
Hepatocellular carcinoma (HCC) is a major cause of cancer worldwide. Proteomic studies provide opportunities to uncover targets for the diagnosis and treatment of this disease. However, in HCC developing in a setting of cirrhosis, the detection of proteome alterations may be hampered by the increased cellular heterogeneity of tissue when analysing global liver homogenates. The aim of this study was to evaluate whether the identification of proteome alterations in these HCC cases was improved when the differential protein profile between tumour and non-tumour areas of liver was determined using hepatocytes isolated by laser microdissection (LM). Differential profiles established with LM-hepatocytes and liver section homogenates using 2-DE and MS exhibited noticeable differences: 30% of the protein spots with deregulated expression in tumorous LM-samples did not display any modification in homogenates; conversely 15% of proteins altered in tumorous homogenates were not impaired in LM-hepatocytes. These alterations resulted from the presence in cirrhotic liver of fibrotic stroma which displayed a protein pattern different from that determined in LM-hepatocytes. In conclusion, our data demonstrate the interest of LM in distinguishing between fibrotic and hepatocyte proteome alterations and thus the benefit of LM to proteome studies of HCC developing in a context of cirrhosis. 相似文献
8.
The UML as a formal modeling notation 总被引:6,自引:0,他引:6
The Unified Modeling Language (UML) is an Object Management Group (OMG) object-oriented (OO) modeling notation standard. It consists of a set of notations for modeling systems from a variety of views and at varying levels of abstraction. While the UML reflects some of the best OO modeling experiences available, it suffers from a lack of precise semantics that is necessary if one is to use the notations to precisely model systems and to rigorously reason about the models. In this paper we discuss some of the problems with the current UML semantic document and present the approach that the precise UML group (pUML) group is using to develop a precise semantics for the UML. The approach utilizes mathematical techniques to explore and gain insights into appropriate semantics for UML modeling concepts. The insights and formal expressions will then be used to develop a UML semantics document written in natural language that defines the semantics in a precise, consistent, and understandable manner. 相似文献
9.
WANG Jiang FAUTRELLE Yves REN Zhong-ming LI Xi NGUYEN-THI Henri MANGELINCK-NOEL Nathalie SALLOUM ABOU JAOUDE Georges ZHONG Yun-bo KALDRE Imants BOJAREVICS Andris BULIGINS Leonid 《钢铁研究学报(英文版)》2012,(Z1):381-385
Sn-3wt%Pb alloy was directionally solidified without and with a 0.08T transverse magnetic field(TMF),and real-time recorded by in-situ synchrotron X-ray imaging.Results indicate that TMF shortened the distance from the location of nucleation to the advancing interface,and accelerated the growth rate of the equiaxed crystal,which caused the columnar-to-equiaxed transition(CET)finally.The thermoelectromagnetic convection(TEMC)in front of the interface and around the crystal’s dendritic branch should respond to changes of the distance and the growth rate. 相似文献
10.
Maxime Schwertz Pierre Ranque Sébastien Lemonnier Elodie Barraud Adele Carradò Marie‐France Vallat Michel Nardin 《应用聚合物科学杂志》2015,132(9)
The present study deals with the optimization of polyimide (PI) mechanical properties, obtained by Spark Plasma Sintering (SPS), by using a method combining Design of Experiments (DOE) with physical, structural, and mechanical characterizations. The effects of SPS parameters such as temperature, pressure, dwell time, and cooling rate on the density, mechanical properties, and structure of PI were investigated. The experimental results revealed that the mechanical properties of the material were optimized by raising the sintering temperature up to 350°C. The optimized SPS processing parameters were a temperature of 350°C, a pressure of 40 MPa, and a dwell time of 5 min. Under these conditions, a relative density of 99.6% was reached within only a few minutes. The corresponding mechanical properties consisted of Young's modulus of 3.43 GPa, a Shore D hardness of 87.3, and a compressive strength of 738 MPa for a maximum compressive strain of 61.8%. Moreover, when working at 320°C and at 100 MPa, an increase in the dwell time was necessary to enhance the properties. Contrary to the other parameters, the cooling rate appeared to be a non‐significant parameter. Finally, correlations between the PI structure and the mechanical properties were made to demonstrate the densification mechanisms. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41542. 相似文献