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Same Correlation (same + correlation)
Selected AbstractsCorrelation between richness per unit area and the species pool cannot be used to demonstrate the species pool effectJOURNAL OF VEGETATION SCIENCE, Issue 1 2000Herben Abstract. Significant correlation between the size of the species pool and richness per unit area is usually taken as a demonstration of the effect of the species pool on the species richness per unit area. This is not logically necessary. It has to be emphasized that such a correlation cannot be interpreted as a demonstration of the effect of species pool on the species richness per unit area. More generally, correlation cannot be used to demonstrate a one-directional effect of one variable upon another, since several types of (functional) relationships could produce correlations between such variables; the same caution has to be taken when analysing the species pool vs. richness per unit area correlation. In this paper, a simple Monte Carlo simulation model is used to demonstrate that (1) statistical processes acting only at the local scale (such as competitive exclusion) can generate exactly the same correlation that has been used to infer the effect of the species pool on richness per unit area; (2) this correlation would be deemed significant even if the mathematical dependency between species pool and richness per unit area is taken into account; and (3) the strength of this relation depends on beta diversity within the contiguous area used to determine the species pool. [source] QSAR Study of 2,3-Benzodiazepin-4(thi)one- and 1,2-Phthalazine-Related Negative Allosteric Modulators of the AMPA Receptor: A Structural Descriptors-Based ReassessmentMOLECULAR INFORMATICS, Issue 3 2005Peter Buchwald Abstract In an attempt to establish statistically more rigorous and chemically more meaningful quantitative structure-activity relationship (QSAR) equations, a reassessment of a recent study of in vivo anticonvulsant activity for a set of 2,3-benzodiazepin-4(thi)one- and 1,2-phthalazine-related allosteric AMPA antagonists (n=61) is presented. Contrary to the original, relatively nonspecific descriptor set, which included, for example, a number of topological descriptors, specific structural descriptors that are much easier to interpret from a medicinal chemical point of view are used in this multiple linear regression-based approach. Only statistically significant descriptors have been retained in the final equation, and whereas they give about the same correlation as those of the original paper on the training set (r2 of 0.79 vs. 0.76, n=49), they perform much better on the test set (predictive r of 0.73 vs. 0.05; r2 of 0.78 vs. 0.08, n=12). Descriptors found to be relevant are clearly related to substitutions at known pharmacophore positions, such as those corresponding to the 2,3-, 7,8- and 4,-positions of the benzodiazepine skeleton. Therefore, by a more careful selection of the descriptor set, both an improved prediction and a more intuitive quantitative interpretation could be achieved for this set of allosteric AMPA antagonists. [source] Multilevel Anthropogenic Cycles of Copper and Zinc: A Comparative Statistical AnalysisJOURNAL OF INDUSTRIAL ECOLOGY, Issue 1-2 2006Barbara Reck Contemporary cycles for copper and zinc are coanalyzed with the tools of exploratory data analysis. One-year analyses (circa 1994) are performed at three discrete spatial levels-country (52 countries that comprise essentially all anthropogenic stocks and flows of the two metals), eight world regions, and the planet as a whole-and are completed both in absolute magnitude and in per capita terms. This work constitutes, to our knowledge, the first multiscale, multilevel analysis of anthropogenic resources throughout their life cycles. The results demonstrate that (1) A high degree of correlation exists between country-level copper and country-level zinc rates of fabrication and manufacturing, entry into use, net addition to in-use stocks, discard, and landfilling; (2) Regional-level rates for copper and zinc cycle parameters show the same correlations as exist at country level; (3) On a per capita basis, countries add to in-use stock almost 50% more copper than zinc; (4) The predominant discard streams for copper and zinc at the global level are different for the two metals, and relative rates of different loss processes differ geographically, so that resource recovery policies must be designed from metalspecific and location-specific perspectives; (5)When absolute magnitudes of life-cycle flows are considered, the standard deviations of the data sets decrease from country level to regional level for both copper and zinc, which is not the case for the per capita data sets, where the statistical properties of the dat sets for both metals approach being independent of spatial level, thus providing a basis for predicting unmeasured per capita metal flow behavior. [source] Cytologic, hormonal, and ultrasonographic correlates of the menstrual cycle of the New World monkey Cebus apellaAMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2005R.E. Ortiz Abstract Few reports on the reproductive physiology of Cebus apella have been published. In this study we characterized menstrual cycle events by means of vaginal cytology, ultrasonography (US), and hormonal measurements in serum during three consecutive cycles in 10 females, and assessed the probability that ovulation would occur in the same ovary in consecutive cycles in 18 females. The lengths and phases of the cycles were determined according to vaginal cytology. Taking the first day of endometrial bleeding as the first day of the cycle, the mean cycle length ± SEM was 19.5±0.4 days, with follicular and luteal phases lasting 8.2±0.2 and 11.3±0.4 days, respectively. The follicular phase included menstruation and the periovulatory period, which was characterized by the presence of a large number of superficial eosinophilic cells in the vaginal smear. The myometrium, endometrium, and ovaries were clearly distinguished on US examination. During each menstrual cycle a single follicle was recruited at random from either ovary. The follicle grew from 3 mm to a maximum diameter of 8,9 mm over the course of 8 days, in association with increasing estradiol (E2) serum levels (from 489±41 to 1600±92 pmol/L). At ovulation, the mean diameter of the dominant follicle usually decreased by >20%, 1 day after the maximum E2 level was reached. Ovulation was associated with an abrupt fall in E2, a decreased number of eosinophilic cells, the presence of leukocytes and intermediate cells in the vaginal smear, and a progressive increase in progesterone (P) levels that reached a maximum of 892±65 nmol/L on days 3,6 of the luteal phase. The menstrual cycle of Cebus apella differs in several temporal and quantitative aspects from that in humans and Old World primates, but it exhibits the same correlations between ovarian endocrine and morphologic parameters. Am. J. Primatol. 66:233,244, 2005. © 2005 Wiley-Liss, Inc. [source] | ||||||||||