Multivariate Correlation in the Framework of Support and Spatial Scales of Variability     

J. A. Vargas-Guzmáan  A. W. Warrick  D. E. Myers 《Mathematical Geology》1999,31(1):85-103

This paper extends the concept of dispersion variance to the multivariate case where the change of support affects dispersion covariances and the matrix of correlation between attributes. This leads to a concept of correlation between attributes as a function of sample supports and size of the physical domain. Decomposition of dispersion covariances into the spatial scales of variability provides a tool for computing the contribution to variability from different spatial components. Coregionalized dispersion covariances and elementary dispersion variances are defined for each multivariate spatial scale of variability. This allows the computation of dispersion covariances and correlation between attributes without integrating the cross-variograms. A correlation matrix, for a second-order stationary field with point support and infinite domain, converges toward constant correlation coefficients. The regionalized correlation coefficients for each spatial scale of variability, and the cases where the intrinsic correlation hypothesis holds are found independent of support and size of domain. This approach opens possibilities for multivariate geostatistics with data taken at different support. Two numerical examples from soil textural data demonstrate the change of correlation matrix with the size of the domain. In general, correlation between attributes is extended from the classic Pearson correlation coefficient based on independent samples to a most general approach for dependent samples taken with different support in a limited domain.  相似文献   

Analysis of nonlinear associations between prenatal methylmercury exposure from fish consumption and neurodevelopmental outcomes in the Seychelles Main Cohort at 17 years     

Li-Shan?HuangEmail authorView author&#;s OrcID profile  Deborah?A.?Cory-Slechta  Christopher?Cox  Sally?W.?Thurston  Conrad?F.?Shamlaye  Gene?E.?Watson  Edwin?van Wijngaarden  Grazyna?Zareba  J.?J.?Strain  Gary?J.?Myers  Philip?W.?Davidson 《Stochastic Environmental Research and Risk Assessment (SERRA)》2018,32(4):893-904

The Seychelles Child Development Study has been examining the relationship between prenatal methylmercury (MeHg) exposure from consuming fish during pregnancy and child development. This study re-analyzes seven outcomes in the 17 year Main Cohort data to determine if there are nonlinear or non-homogeneous (subgroup) associations that were not identified in the linear analysis. We adopted two statistical approaches. First, we carried out an additive nonlinear analysis assuming homogeneous prenatal MeHg-outcome relationships to explore overall associations. Second, we applied the regression tree to the Woodcock–Johnson Calculation subtest (it was significantly associated in earlier analyses) and identified 4 clusters based on covariates. Then we used additive models to assess the prenatal MeHg association in each of the four clusters for all seven outcomes. This approach assumes nonlinear associations in each cluster and non-homogeneous associations between clusters. The additive nonlinear analysis yielded prenatal MeHg curves similar to the linear analysis. For the regression tree analysis, the curves relating prenatal MeHg to outcomes between the 4 clusters differed and some crossed at higher prenatal MeHg levels, suggesting non-homogeneity in the upper range of exposure. Additionally, some of the curves suggested a possible non-linear relationship within the range of exposure we studied. This non-linear analysis supports the findings from the linear analysis. It shows little evidence to support an adverse association of prenatal MeHg exposure through maternal consumption of fish contaminated with natural background levels. However, the tree analysis suggests that the prenatal exposure/outcome relationship may not be homogeneous across all individuals and that some subpopulations may have an adverse association in the upper range of the exposures studied. More robust data in the higher levels of exposure in this cohort are needed to confirm this finding.  相似文献   

Variance as a function of sample support size     

R. Zhang  A. W. Warrick  D. E. Myers 《Mathematical Geology》1990,22(1):107-121

The effect of sample support size on variance is examined and evaluated. Results based on variograms and geostatistics are compared to the classical relationship developed by H. F. Smith in 1938; that is, that the variance is reduced fromV ₁ toV ₁ /n ^b as the support area increases from I ton plots for uniformity trials. The exponentb is between zero and one. Theoretical results are based on use of auxiliary functions and account for the size and shape of the sample support and the overall field geometry. Results are given in terms of approximations by rational functions for ease of calculation. Experimental results for uniformity trials, infiltration measurements, and spectral data from satellites are compared to theoretical and empirical results. Applications include not only uniformity trials, but also measurement theory.  相似文献   

A statistical-mechanics model of ordering in aluminosilicate solid solutions     

Eva R. Myers 《Physics and Chemistry of Minerals》1998,25(6):465-468

A statistical-thermodynamic approximation for order-disorder phase transitions in aluminosilicate solid solutions is presented. The approximation involves estimating the number of configurations with long range order parameter Q and short range order parameter σ, using an approximation to the probability that a configuration with the correct amount of long range order will also have the correct amount of short range order. This estimate is then used to give a free energy F(Q, σ, x, T), where x is the concentration of Al in the structure, and hence quantities such as T _c (x) are estimated. The predictions of the model for T _c (x) and the critical concentration x _c at which T _c falls to zero are shown to be in good agreement with the results of Monte Carlo simulations. Received: 14 May 1997 / Revised, accepted: 2 June 1997  相似文献   

Lutz Creek watershed,Barro Colorado Island,Republic of Panama     

Matthew C. Larsen PhD  Robert F. Stallard PhD  Steven Paton MS 《水文研究》2021,35(4):e14157

Lutz creek is a small (9.69 ha) catchment located on Barro Colorado Island (BCI), a 1500-ha island in Lake Gatún, the principal freshwater reservoir (425 ha, 26 m above sea level) of the Panama Canal watershed in central Panama. In 1972, a concrete V-notch weir was installed on the creek, located at 9°09′42.8358″N, 79°50′15.6699″W, and hydrological record keeping began. The island was first established as a research station in 1923 and precipitation data collection was initiated in 1925. A meteorological tower, installed in 1972 and located a few meters from the weir, is currently instrumented to collect air temperature, relative humidity, wind speed and direction, evapotranspiration and solar radiation. In addition, since 1972, gravimetric soil moisture has been measured at least biweekly at 10 sites located throughout the Lutz Catchment above the location of the weir. Data collection and the administration of BCI are the responsibility of the Smithsonian Tropical Research Institute (STRI; https://stri.si.edu ) which funds the data collection and storage. Data are in the public domain, entitled ‘Lutz Watershed And Meteorological Tower’ and are available at the STRI Physical monitoring website https://biogeodb.stri.si.edu/physical_monitoring/ .  相似文献   

Integration of airborne thematic mapper simulator (TMS) data and digitized aerial photography via an ISH transformation     

Vincent G. Ambrosia  Jeffrey S. Myers  Robert E. Ekstrand  Michael T. Fitzgerald 《国际地球制图》2013,28(2):45-48

Abstract

In water sampling it is very common to use human experience to determine sampling locations. We present results from a neural network analysis of multispectral imaging data from the Compact Airborne Spectrographic Imager (casi) to determine significant water sampling locations. In this study Lake Tegel in Berlin, Germany, was overflown on different days. The analysis of the remote sensing data results in a clustering of the overflown water body for each pass. The neural network clusters found for each pass have been related to each other. This procedure enables us to optimize the number and location of water sampling stations.  相似文献   

Recognizable primary volcanic and sedimentary features in a low-strain domain of the highly deformed, oldest known (≈ 3.7–3.8 Gyr) Greenstone Belt, Isua, West Greenland     

Appel  Fedo  Moorbath  & Myers 《地学学报》1998,10(2):57-62

A low-strain domain has been identified in the metamorphosed, mostly highly deformed volcanic and sedimentary rocks of the early Archaean Isua supracrustal belt. This domain contains well-preserved volcanic and sedimentary features, including basaltic pillow lavas, pillow breccia, heterogeneous volcanic breccia, amygdules in metabasalt, and polymict conglomerate dominated by recrystallized chert and volcanic clasts. The low-strain domain is bounded by highly deformed rocks mostly derived from basalt, chert, and banded iron formation. These discoveries demonstrate that some primary features have escaped the pervasive metasomatism dominant in other parts of the belt and, furthermore, strengthen the characterization of the Isua supracrustals as a typical greenstone belt.  相似文献   

Chronology and evolution of the Middle Proterozoic Albany‐Fraser Orogen,Western Australia     

D. R. Nelson  J. S. Myers  A. P. Nutman 《Australian Journal of Earth Sciences》2013,60(5):481-495

Geochemical and Sm‐Nd isotopic data, and 19 ion‐microprobe U‐Pb zircon dates are reported for gneiss and granite from the eastern part of the Albany‐Fraser Orogen. The orogen is dominated by granitic rocks derived from sources containing both Late Archaean and mantle‐derived components. Four major plutonic episodes have been identified at ca 2630 Ma, 1700–1600 Ma, ca 1300 Ma and ca 1160 Ma. Orthogneiss, largely derived from ca 2630 Ma and 1700–1600 Ma granitic precursors, forms a belt along the southeastern margin of the Yilgarn Craton. These rocks, together with gabbro of the Fraser Complex, were intruded by granitic magmas and metamorphosed in the granulite facies at ca 1300 Ma. They were then rapidly uplifted and transported westward along low‐angle thrust faults over the southeastern margin of the Yilgarn Craton. Between ca 1190 and 1130 Ma, granitic magmas were intruded throughout the eastern part of the orogen. These new data are integrated into a review of the geological evolution of the Albany‐Fraser Orogen and adjacent margin of eastern Antarctica, and possibly related rocks in the Musgrave Complex and Gawler Craton.  相似文献   

Effects of antifouling biocides to the germination and growth of the marine macroalga, Hormosira banksii (Turner) Desicaine     

Myers JH  Gunthorpe L  Allinson G  Duda S 《Marine pollution bulletin》2006,52(9):1048-1055

The International Maritime Organisation's (IMO) ban on the use of tributyltin in antifouling paints has inevitability increased the use of old fashioned antifoulants and/or the development of new paints containing 'booster biocides'. These newer paints are intended to be environmentally less harmful, however the broader environmental effects of these 'booster biocides' are poorly known. Germination and growth inhibition tests using the marine macroalga, Hormosira banksii (Turner) Desicaine were conducted to evaluate the toxicity of four new antifouling biocides in relation to tributyltin-oxide (TBTO). Each of the biocides significantly inhibited germination and growth of Hormosira banksii spores. Toxicity was in increasing order: diuron < zineb < seanine 211< zinc pyrithione < TBTO. However, the lack of knowledge on partitioning in the environment makes it difficult to make a full assessment on whether the four biocides tested offer an advantage over organotin paints in terms of environmental impact.  相似文献   

CLASS B0631+519: last of the Cosmic Lens All-Sky Survey lenses     

T. York  N. Jackson  I. W. A. Browne  L. V. E. Koopmans  J. P. McKean  M. A. Norbury  A. D. Biggs  R. D. Blandford  A. G. de Bruyn  C. D. Fassnacht  S. T. Myers  T. J. Pearson  P. M. Phillips  A. C. S. Readhead  D. Rusin  P. N. Wilkinson 《Monthly notices of the Royal Astronomical Society》2005,361(1):259-271

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