Correlations positive

Some variables often have dependencies, such as reservoir porosity and permeability (a positive correlation) or the capital cost of a specific equipment item and its lifetime maintenance cost (a negative correlation). We can test the linear dependency of two variables (say x and y) by calculating the covariance between the two variables (o ) and the correlation coefficient (r) ... 

The value of r varies between plus and minus one, the positive values indicating a positive correlation (as x increases, so does y), and the negative values indicating a... 

The essential degrees of freedom are found by a principal component analysis of the position correlation matrix Cy of the cartesian coordinate displacements Xi with respect to their averages xi), as gathered during a long MD run ... 

As wc can sec from Figure 4-8. variables 1, 8, and 11 arc the most significant ones, variables 4, 9, and 10 much less so, variables 2 and 5 are highly and positively correlated, the whole group of variables 2,. 3, 4, and 5 are more or less similar, and variables 9 and 4 arc inversely correlated. 

The purpose of this eornpuLer project is Lo examine several polynuclear aromatic hydrocarbons and to relate their electron density patterns to their carcinogenic activity. If nucleophilic binding to DN.A is a significant step in blocking the normal transcription process of DN.A, electron density in the hydrocarbon should be positively correlated to its carcinogenic potency. To begin with, we shall rely on clinical evidence that benzene, naphthalene, and phenanthrene... 

Acute toxicoses, as well as potential long-term effects of aflatoxki ingestion, have been extensively reported (93). Autopsy reports have noted a positive correlation between aflatoxki B and victims of Reye s Syndrome ki Thailand (94), but this evidence should only be considered as suggestive and preliminary (95). 

Sulfonylurea herbicides ate weak acids and, in general, ate not strongly sorbed to soils. Sorption of chlotsulfuton and metsulfuron—methyl is inversely related to soil pH (407) and is positively correlated to soil organic matter (408). 

There appear also to be toxic effects. In animals, nitrous oxide has been shown to inactivate methionine synthetase which prevents the conversion of deoxyuridine to thymidine and thus has the potential for inducing megaloblastic anemia, leukopenia, and teratogenicity (44—46). A variety of epidemiologic surveys suggest positive correlations between exposure to nitrous oxide and spontaneous abortion in dental assistants (47). 

Values of / near 1 indicate a positive correlation / near —1 means a negative correlation and / near zero means no correlation. 

If the normalized method is used in addition, the value of Sjj is 3.8314 X 10 /<3 , where <3 is the variance of the measurement of y. The values of a and h are, of course, the same. The variances of a and h are <3 = 0.2532C , cf = 2.610 X 10" <3 . The correlation coefficient is 0.996390, which indicates that there is a positive correlation between x and y. The small value of the variance for h indicates that this parameter is determined very well by the data. The residuals show no particular pattern, and the predictions are plotted along with the data in Fig. 3-58. If the variance of the measurements of y is known through repeated measurements, then the variance of the parameters can be made absolute. 

CO) may contain elastic (co = 0) and inelastic (co 0) parts. Elastic scattering probes correlations of atomic positions at long times, whereas the inelastic scattering process probes position correlations as a function of time. 

Fig. 12 shows the atom density profiles as a function of the coordinate z along the pore axis. Oxygen atom positions correlate with positive and negative surface charges as a result of direct hydration and through hydrogen bonds, respectively. In a similar manner the maxima of the and CP density... 

What are the essential features of surfactant systems An important ingredient is obviously the repulsion between water and nonpolar molecules or molecule parts, the hydrophobic force. This interaction is however highly nontrivial, and its analysis is still an active field of research [4,22,23]. Qualitatively, it is usually attributed to the strong orientational and positional correlations between nonpolar molecules in solution and the surrounding water molecules. The origin of the interaction is therefore entropic free water forms a network of hydrogen bonds. In the neighborhood... 

The correlation coefficient ranges between 1 and — 1. A perfect positive correlation has r=l, no correlation at all is r = 0, and a perfect negative correlation r= —1. Some examples of correlations are shown in Figure 11.5b. A measure of the significance of a relationship between two variables can be gained by calculating a value of t ... 

Daudel, R., Brion, H., and Odiot, S., J. Chem. Phys. 23, 2080, Localizability of electrons in atoms and molecules—application to the study of the notion of shell and of the nature of chemical bonds." Decomposition of the space of an electronic system into small parts where there is a very large probability of finding one and only one electron of a given spin. Discussion of the positional correlation between only one sort of spin, not that of two sorts of spin. 

Kluk E., Monkos K., Pasterny K., Zerda T. A means to obtain angular velocity correlation functions from angular position correlation functions of molecules in liquid. Part I. General discussion and its application to linear and spherical top molecules, Acta Physica Polonica A 56, 109-16 (1979). 

Fig. 1-2 Chemical data from the Vostok ice core. The graph of 5D can be taken as a proxy for temperature changes, as described in Chapter 18. CO2 and CH4 are greenhouse gases and vary in the same direction as temperature. Non-seasalt sulfate and methane sulfonic acid are both sulfur species existing in the particle phase, and are positively correlated with each other, but negatively with T. Major variations for all of these variables seem to correlate either positively or negatively with each other, indicating a coupled system. <5D, non-seasalt sulfate, and methane sulfonic acid data kindly provided by Dr Eric Saltzman. CO2 data are from Bamola et al. (1987) and Jouzel et al. (1993). CH4 data are from Chappellaz et al. (1990) and Jouzel et al. (1993). (ppmv = parts per million by volume ppbv = parts per billion by volime)...

The influence that variations of temperature and levels of atmospheric CO2 and O2 have on chemical weathering are more subtle. Temperature appears to have a direct effect on weathering rate (White and Blum, 1995). The silica concentration of rivers (Meybeck, 1979, 1987) and the alkalinity of ground waters in carbonate terrains (Harmon et al., 1975) are both positively correlated with temperature variations. It is not clear, however, whether temperature-related variations in weathering rates are largely due to variations in vegetational activity that parallel temperature variations. 

Chemically reactive elements should have a short residence time in seawater and a low concentration. A positive correlation exists between the mean ocean residence time and the mean oceanic concentration however, the scatter is too great for the plot to be used for predictive purposes. Whitfield and Turner (1979) and Whitfield (1979) have shown that a more important correlation exists between residence time and a measure of the partitioning of the elements between the ocean and crustal rocks. The rationale behind this approach is that the oceanic concentrations have been roughly constant, while the elements in crustal rocks have cycled through the oceans. This partitioning of the elements may reflect the long-term chemical controls. The relationship can be summarized by an equation of the form... 

Longer ice-core records show that methane concentrations have varied on a variety of time scales over the past 220 000 years (Fig. 18-15) Qouzel et al, 1993 Brook et al, 1996). Wetlands in tropical (30° S to 30° N) and boreal (50° N to 70° N) regions are the dominant natural methane source. As a result, ice-core records for preanthropogenic times have been interpreted as records of changes in methane emissions from wetlands. Studies of modem wetlands indicate that methane emissions are positively correlated with temperature, precipitation, and net ecosystem productivity (Schlesinger, 1996). 

The characteristics of the changes in several species discussed in this chapter are shown in Fig. 19-3. This figure depicts the changing composition of the atmosphere on three time scales. Figures 19-3a-c show the simultaneous variation of CO2, CH4, temperature, and SO from the Vostok ice core (see also Fig. 1-2). These records also clearly demonstrate that the Earth functions as a coupled system. Temperature, CO2 and CH4 are positively correlated with one another, but each is negatively correlated with (for reasons that are not yet known). This time period covers 160000 years including the... 

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