排序方式： 共有23条查询结果，搜索用时 15 毫秒
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Leaños-Castañeda O Gold-Bouchot G Van Der Kraak G Lister A Ceja-Moreno V Simá-Alvarez R 《Marine environmental research》2004,58(2-5):337-342
The objective of this study was to determine if tamoxifen or an aromatase inhibitor (4-hydroxyandrostenedione; 4-OHA) affected plasma concentrations of o,p' -DDT and its metabolites, o,p'-DDD and o,p'-DDE, in mature tilapia. Male and female tilapia were injected 6 times intraperitoneally with o,p'-DDT (40 mg/kg) alone or in combination with 4-OHA (2 mg/kg) over a 12 day period. An additional group of male fish was injected with tamoxifen (5 mg/kg) plus o,p'-DDT. At the end of the treatment period, plasma samples were extracted and analyzed by GC/ECD. Females injected only with o,p'-DDT had significantly higher levels of o,p'-DDT compared with males. Interestingly, females and males treated concomitantly with o,p'-DDT and 4-OHA or tamoxifen had significantly lower concentrations of plasma o,p'-DDT (about 50%) compared with fish treated with only o,p'-DDT. These initial results suggest that an interaction between endocrine-active compounds occurs in vivo in tilapia and may involve alterations in metabolism of o,p'-DDT. 相似文献
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Norhakim Yusof Raul Zurita-Milla Menno-Jan Kraak Bas Retsios 《International journal of geographical information science》2016,30(8):1486-1506
Wind speed and direction vary over space and time due to the interactions between different pressures and temperature gradients within the atmospheric layers. Near the earth’s surface, these interactions are modulated by topography and artificial structures. Hence, characterizing wind behaviour over large areas and long periods is a complex but essential task for various energy-related applications. In this study, we present a novel approach to discover wind patterns by integrating sequential pattern mining and interactive visualization techniques. The approach relies on the use of the Linear time Closed pattern Miner sequence algorithm in conjunction with a time sliding window that allows the discovery of all sequential patterns present in the data. These patterns are then visualized using integrated 2D and 3D coordinated multiple views and visually explored to gain insight into the characteristics of the wind from a spatial, temporal and attribute (type of wind pattern) point of view. This proposed approach is used to analyse 10 years of hourly wind speed and direction data for 29 weather stations in the Netherlands. The results show that there are 15 main sequential patterns in the data. The spatial task shows that weather stations located in the same region do not necessarily experience similar wind pattern. For within the selected time interval, similar wind patterns can be observed in different stations and in the same station at different times of occurrence. The attribute task discovered that the repetitive occurrences of chosen pattern indicate as regular wind behaviour at different weather stations that persisted continuously over time. The results of these tasks show that the proposed interactive discovery facilitates the understanding of wind dynamics in space and time. 相似文献
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Irma Kveladze Menno-Jan Kraak Corné P.J.M. Van Elzakker 《International journal of geographical information science》2015,29(11):2001-2016
This paper reports the results of an empirical usability experiment on the performance of the space-time cube in a GeoVisual analytics environment. It was developed to explore movement data based on the requirements of human geographers. The interactive environment consists of multiple coordinated views incorporating three graphical representations. For the experiment, two groups of the user, domain experts and non-domain experts, had to execute several map-use tasks to answers specific question. The data collected during the experiment were analysis resulting in a set of usability metrics related to the effectiveness, efficiency and user satisfaction of developed application. The comparison of both groups showed that domain experts were able to operate the visual analytical environment more effectively and efficiently due to their interest to explore their data. The user feedback derived from the analysis of both experiments was further processed for the improvement of the application. 相似文献
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This paper reports on the results of an empirical evaluation that aimed to define the effectiveness and efficiency of different visual variables in depicting the Space–Time Cube’s (STC) content. Existing STC applications demonstrate that the most used visual variables are size and colour hue. Less is known, however, about their usability metrics. The research sets design criteria for STC contents, such as space–time paths, based on the cartographic design theory. The visual variables colour hue, colour value, colour saturation, size and orientation have been applied in two different use case studies. Besides, to support the three-dimensional visual environment, depth cues such as shading and transparency were considered too. User tests have been executed based on real-world problems with particular attention for the visualization strategy and data complexity. The outcomes revealed the most efficient and effective visual variables to represent data of various complexities in the STC. 相似文献
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Olga Leaos-Castaeda Glen Van Der Kraak Andrea Lister Raúl Sim-Alvarez Gerardo Gold-Bouchot 《Marine environmental research》2002,54(3-5)
In order to investigate the mechanism by which o,p′-DDT disrupts endocrine functioning of Nile tilapia in vivo, the estrogenicity of o,p′-DDT was investigated in conjunction with 17β-estradiol (E2) and tamoxifen. Mature, male tilapia were treated intraperitoneally with o,p′-DDT (60 mg/kg, one dose) or E2 (5 mg/kg, four doses) in the presence or absence of tamoxifen (5 mg/kg, six doses) for 12 days and then plasma vitellogenin (Vtg) (measured as alkaline-labile phosphorous), E2, and testosterone (T) were measured. Vtg levels were increased dramatically by E2 (1744±171 μg/ml) and moderately by o,p′-DDT (82±15 μg/ml) compared with controls (23±3.5 μg/ml). Tamoxifen alone had no effect on Vtg production, but inhibited both E2 and o,p′-DDT stimulated vitellogenesis. T levels were reduced with E2 administration (1688±383 pg/ml) and declined further with the combined treatment of E2 and tamoxifen (281±70 pg/ml), compared with controls (6558±1438 pg/ml). Tamoxifen or o,p′-DDT alone did not affect T levels, but their combined treatment did (2069±647 pg/ml). The results of this study suggest that o,p′-DDT is weakly estrogenic in male tilapia, and that this activity may be mediated through the estrogen receptor. 相似文献
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This paper focuses on the methods and process of spatial aggregation based on semantic and geometric characteristics of spatial objects and relations among the objects with the help of spatial data structure (Formal Data Structure), the Local Constrained Delaunay Triangulations and semantic hierarchy. The adjacent relation among connected objects and unconnected objects has been studied through constrained triangle as elementary processing unit in aggregation operation. The hierarchical semantic analytical matrix is given for analyzing the similarity between objects types and between objects. Several different cases of aggregation have been presented in this paper. 相似文献
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Leaños-Castañeda O Van Der Kraak G Lister A Simá-Alvarez R Gold-Bouchot G 《Marine environmental research》2002,54(3-5):703-707
In order to investigate the mechanism by which o,p'-DDT disrupts endocrine functioning of Nile tilapia in vivo, the estrogenicity of o,p'-DDT was investigated in conjunction with 17beta-estradiol (E2) and tamoxifen. Mature, male tilapia were treated intraperitoneally with o,p'-DDT (60 mg/kg, one dose) or E2 (5 mg/kg, four doses) in the presence or absence of tamoxifen (5 mg/kg, six doses) for 12 days and then plasma vitellogenin (Vtg) (measured as alkaline-labile phosphorous), E2, and testosterone (T) were measured. Vtg levels were increased dramatically by E2 (1,744 +/- 171 microg/ml) and moderately by o,p'-DDT (82 +/- 15 microg/ml) compared with controls (23 +/- 3.5 microg/ml). Tamoxifen alone had no effect on Vtg production, but inhibited both E2 and o,p'-DDT stimulated vitellogenesis. T levels were reduced with E2 administration (1,688 +/- 383 pg/ml) and declined further with the combined treatment of E2 and tamoxifen (281 +/- 70 pg/ml), compared with controls (6,558 +/- 1,438 pg/ml). Tamoxifen or o,p'-DDT alone did not affect T levels, but their combined treatment did (2,069 +/- 647 pg/ml). The results of this study suggest that o,p'-DDT is weakly estrogenic in male tilapia, and that this activity may be mediated through the estrogen receptor. 相似文献