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Original Analysis (original + analysis)
Selected AbstractsUsing the Survey of Consumer Finances: Some Methodological Considerations and IssuesJOURNAL OF CONSUMER AFFAIRS, Issue 2 2007SUZANNE LINDAMOOD We identify and present original analyses of four methodological issues related to using Survey of Consumer Finances data sets and illustrate these issues with recent articles published in this journal. The issues are recognizing that the respondent is not necessarily the household head, reporting race and ethnicity in conformity with Survey of Consumer Finances and federal standards, using the repeated-imputation inference method to combine the five implicates in each survey year's data set, and discussing the use of weighted or unweighted data in multivariate analysis. We found a considerable variation in how authors dealt with these issues, which could hinder replication or comparison of research results. Authors and reviewers should consider methodological issues related to the Survey of Consumer Finances more carefully. [source] The evolution of substructure in galaxy, group and cluster haloes , III.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2005Comparison with simulations ABSTRACT In a previous paper, we described a new method for including detailed information about substructure in semi-analytic models of halo formation based on merger trees. In this paper, we compare the predictions of our model with results from self-consistent numerical simulations. We find that in general the two methods agree extremely well, particularly once numerical effects and selection effects in the choice of haloes are taken into account. As expected from the original analyses of the simulations, we see some evidence for artificial overmerging in the innermost regions of the simulated haloes, either because substructure is being disrupted artificially or because the group-finding algorithms used to identify substructure are not detecting all the bound clumps in the highest-density regions. Our analytic results suggest that greater mass and force resolution may be required before numerical overmerging becomes negligible in all current applications. We discuss the implications of this result for observational and experimental tests of halo substructure, such as the analysis of discrepant magnification ratios in strongly lensed systems, terrestrial experiments to detect dark matter particles directly or indirect detection experiments searching for positrons, gamma-rays, neutrinos or other dark matter decay or annihilation products. [source] On the Analyses of Mixture Vapor Pressure Data: The Hydrogen Peroxide/Water System and Its Excess Thermodynamic FunctionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 24 2004Stanley L. Manatt Dr. Abstract Reported here are some aspects of the analysis of mixture vapor pressure data using the model-free Redlich,Kister approach that have heretofore not been recognized. These are that the pure vapor pressure of one or more components and the average temperature of the complex apparatuses used in such studies can be obtained from the mixture vapor pressures. The findings reported here raise questions regarding current and past approaches for analyses of mixture vapor pressure data. As a test case for this analysis approach the H2O2,H2O mixture vapor pressure measurements reported by Scatchard, Kavanagh, and Tickner (G. Scatchard, G. M. Kavanagh, L. B. Ticknor, J. Am. Chem. Soc.1952, 74, 3715,3720; G. M. Kavanagh, PhD. Thesis, Massachusetts Institute of Technology (USA), 1949) have been used; there is significant recent interest in this system. It was found that the original data is fit far better with a four-parameter Redlich,Kister excess energy expansion with inclusion of the pure hydrogen peroxide vapor pressure and the temperature as parameters. Comparisons of the present results with the previous analyses of this suite of data exhibit significant deviations. A precedent for consideration of iteration of temperature exists from the little-known work of Uchida, Ogawa, and Yamaguchi (S. Uchida, S. Ogawa, M. Yamaguchi, Japan Sci. Eng. Sci.1950, 1, 41,49) who observed significant variations of temperature from place to place within a carefully insulated apparatus of the type traditionally used in mixture vapor pressure measurements. For hydrogen peroxide, new critical constants and vapor pressure,temperature equations needed in the analysis approach described above have been derived. Also temperature functions for the four Redlich,Kister parameters were derived, that allowed calculations of the excess Gibbs energy, excess entropy, and excess enthalpy whose values at various temperatures indicate the complexity of H2O2,H2O mixtures not evident in the original analyses of this suite of experimental results. [source] THE EVOLUTION OF ENVIRONMENTAL AND GENETIC SEX DETERMINATION IN FLUCTUATING ENVIRONMENTSEVOLUTION, Issue 12 2003Tom J. M. Van Dooren Abstract Twenty years ago, Bulmer and Bull suggested that disruptive selection, produced by environmental fluctuations, can result in an evolutionary transition from environmental sex determination (ESD) to genetic sex determination (GSD). We investigated the feasibility of such a process, using mutation-limited adaptive dynamics and individual-based computer simulations. Our model describes the evolution of a reaction norm for sex determination in a metapopulation setting with partial migration and variation in an environmental variable both within and between local patches. The reaction norm represents the probability of becoming a female as a function of environmental state and was modeled as a sigmoid function with two parameters, one giving the location (i.e., the value of the environmental variable for which an individual has equal chance of becoming either sex) and the other giving the slope of the reaction norm for that environment. The slope can be interpreted as being set by the level of developmental noise in morph determination, with less noise giving a steeper slope and a more switchlike reaction norm. We found convergence stable reaction norms with intermediate to large amounts of developmental noise for conditions characterized by low migration rates, small differential competitive advantages between the sexes over environments, and little variation between individual environments within patches compared to variation between patches. We also considered reaction norms with the slope parameter constrained to a high value, corresponding to little developmental noise. For these we found evolutionary branching in the location parameter and a transition from ESD toward GSD, analogous to the original analysis by Bulmer and Bull. Further evolutionary change, including dominance evolution, produced a polymorphism acting as a GSD system with heterogamety. Our results point to the role of developmental noise in the evolution of sex determination. [source] ,-Crustacyanin, the blue,purple carotenoprotein of lobster carapace: consideration of the bathochromic shift of the protein-bound astaxanthinACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2003P. F. Zagalsky The crystal structure of a ,-crustacyanin allows an analysis of the various proposals for the mechanism of the bathochromic shift from orange to purple,blue of astaxanthin in this lobster carotenoprotein. Structural and previous chemical and biophysical studies suggest that extension of conjugation by coplanarization of the ,-ionone rings with the polyene chain and polarization resulting from hydrogen bonding at the C(4) and C(4,) keto groups may be mainly responsible for the bathochromic shift. Additional contributions may arise from medium effects and possibly from bowing of the polyene chain on binding. Previous biophysical data revealing a somewhat symmetrical polarization of astaxanthin in crustacyanin are thereby also accounted for. A puzzling feature remains unexplained: the bathochromic shifts, larger than that of astaxanthin, shown by some cyclopentenedione carotenoids in reconstituted carotenoproteins. This mini review enlarges on the original analysis and conclusions of Cianci et al. [(2002), Proc. Natl Acad. Sci. USA, 99, 9795,9800]. [source] Levene Tests of Homogeneity of Variance for General Block and Treatment DesignsBIOMETRICS, Issue 1 2002Michael E. O'Neill Summary. This article develops a weighted least squares version of Levene's test of homogeneity of variance for a general design, available both for univariate and multivariate situations. When the design is balanced, the univariate and two common multivariate test statistics turn out to be proportional to the corresponding ordinary least squares test statistics obtained from an analysis of variance of the absolute values of the standardized mean-based residuals from the original analysis of the data. The constant of proportionality is simply a design-dependent multiplier (which does not necessarily tend to unity). Explicit results are presented for randomized block and Latin square designs and are illustrated for factorial treatment designs and split-plot experiments. The distribution of the univariate test statistic is close to a standard F -distribution, although it can be slightly underdispersed. For a complex design, the test assesses homogeneity of variance across blocks, treatments, or treatment factors and offers an objective interpretation of residual plots. [source] 3253: Ocular neurovascular coupling in glaucoma patientsACTA OPHTHALMOLOGICA, Issue 2010K GUGLETA Purpose Defining property of glaucoma, cupping of the optic disc in parallel to loss of retinal ganglion cells and their axon, implies tissue remodeling of the optic nerve head which in turns requires involvement of astrocytes. Their malfunction may lead not only to cupping, but also to disturbance in ocular neurovascular coupling. Methods We analyzed 122 glaucoma patients, ocular hypertensives and healthy controls who all received no IOP-lowering therapy at least four weeks prior to the study examination. One eye per subject entered the primary analysis: in the POAG group, an eye with the biggest damage, in the OHT group an eye with the highest average IOP was selected. Relative vessel diameter increase in response to flicker light was used as the measure of neurovascular coupling. Results This response was impaired in untreated POAG patients, affecting both superior and inferior temporal retinal vessels. In general, inferior vessel dilated more than superior ones. The dilation amplitude was inversely correlated to the level of morphological (retinal nerve fiber layer thickness) and functional (visual field mean defect) glaucomatous damage. Despite the relatively high level of inter- and intraocular correlation of vessel responses, in a separate analysis of contralateral eyes, they seem to display higher dilation amplitudes than the more damaged eyes which were included in the original analysis. Conclusion Neurovascular coupling is impaired in untreated glaucoma patients. Prospective studies are underway in an attempt to clarify the cause versus consequence relationship between the glaucomatous damage and disturbance of neurovascular coupling. 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