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Meaningful Results (meaningful + result)
Selected AbstractsHistorical biogeography of Southeast Asia and the West Pacific, or the generality of unrooted area networks as historical biogeographic hypothesesJOURNAL OF BIOGEOGRAPHY, Issue 2 2003Peter C. van Welzen Abstract Aim Unrooted area networks are perhaps a general way in which different historical biogeographical patterns may be combined. Location Southeast Asia up to the West Pacific, Australia, South America. Methods Unrooted area networks based on Primary Brooks Parsimony Analysis of different data sets of Southeast Asian,West Pacific, Australian and South American clades. Results A large Brooks Parsimony historical (cladistic) biogeographic analysis of Southeast Asia and the West Pacific gave a meaningful result when all clades (representing different historical biogeographic patterns) were united into one matrix and an unrooted area network was produced. This network showed geographically adjacent areas as neighbours, which is interpreted as clades dispersing and speciating as soon as areas rafted towards each other. This pseudo-vicariance mechanism, together with the very limited, mainly linear dispersal possibilities, a few large, widespread clades with many endemic species, and the large overlap in distributions displayed by different patterns, may explain the peculiar result. When applied to examples from other areas (bird data from Australia and South America), unrooted area networks for all data perform very poorly. Main conclusions Unrooted historical general area networks are not universally applicable. In general, it is better to split historical patterns a priori and analyse them separately. [source] Accounting for uncertainty in DEMs from repeat topographic surveys: improved sediment budgetsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 2 2010Joseph M. Wheaton Abstract Repeat topographic surveys are increasingly becoming more affordable, and possible at higher spatial resolutions and over greater spatial extents. Digital elevation models (DEMs) built from such surveys can be used to produce DEM of Difference (DoD) maps and estimate the net change in storage terms for morphological sediment budgets. While these products are extremely useful for monitoring and geomorphic interpretation, data and model uncertainties render them prone to misinterpretation. Two new methods are presented, which allow for more robust and spatially variable estimation of DEM uncertainties and propagate these forward to evaluate the consequences for estimates of geomorphic change. The first relies on a fuzzy inference system to estimate the spatial variability of elevation uncertainty in individual DEMs while the second approach modifies this estimate on the basis of the spatial coherence of erosion and deposition units. Both techniques allow for probabilistic representation of uncertainty on a cell-by-cell basis and thresholding of the sediment budget at a user-specified confidence interval. The application of these new techniques is illustrated with 5 years of high resolution survey data from a 1,km long braided reach of the River Feshie in the Highlands of Scotland. The reach was found to be consistently degradational, with between 570 and 1970,m3 of net erosion per annum, despite the fact that spatially, deposition covered more surface area than erosion. In the two wetter periods with extensive braid-plain inundation, the uncertainty analysis thresholded at a 95% confidence interval resulted in a larger percentage (57% for 2004,2005 and 59% for 2006,2007) of volumetric change being excluded from the budget than the drier years (24% for 2003,2004 and 31% for 2005,2006). For these data, the new uncertainty analysis is generally more conservative volumetrically than a standard spatially-uniform minimum level of detection analysis, but also produces more plausible and physically meaningful results. The tools are packaged in a wizard-driven Matlab software application available for download with this paper, and can be calibrated and extended for application to any topographic point cloud (x,y,z). Copyright © 2009 John Wiley & Sons, Ltd. [source] Sorption kinetics of toluene in humic acid: A computational approachENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2006Yang-Hsin Shih Abstract Molecular dynamics, a computational technique aiming to describe the time-dependent movement of molecules, has been applied to study the sorption kinetics of volatile organic contaminants in soil organic matter. The molecular dynamics simulation results obtain reasonably accurate estimates of diffusion rates and activation energy of the penetration of a volatile organic compound molecule into a model humic substance. The sorption rate of toluene to humic acid decreases with the density of the humic acid matrix and increases with temperature. All the present results indicate that the sorption of toluene into humic acid is mainly diffusion controlled. Finally, the present studies have shown that molecular dynamics of volatile organic compounds in humic substances yields meaningful results, which help in the understanding of diffusion at the molecular level and which facilitate the problem-solving capability for removing the contaminants from the soils. [source] Maternal representations during pregnancy and early motherhoodINFANT MENTAL HEALTH JOURNAL, Issue 1 2004Ebru Taskin Ilicali The aim of the present study was to study the maternal representations of pregnant women and mothers in their early postpartum period, by beginning the process of validating the maternal representations questionnaire L'entretien R1 and by developing a means to assess the content-free aspects of the representations. Participants were 23 primiparous (first-time mothers) pregnant women in their fourth to seventh month of pregnancy and 22 primiparous mothers in their early (zero to six months) postpartum period. It was found that the four subscales of L'entretien (self-as-mother, self-as-person, own-mother, and partner) produced meaningful results for Turkish subjects. The results were compatible with the idea of integrated representations of self-as-person and self-as-mother even in the second trimester of their pregnancy and also showed that they could differentiate themselves from their mothers as early as that period. The results revealed no significant differences in the content and content-free dimensions of the representations of pregnant women and mothers. ©2004 Michigan Association for Infant Mental Health. [source] Application of Histomorphometric Methods to the Study of Bone Repair,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2005Louis C Gerstenfeld Abstract ABSTRACT: Standardized methods for the histomorphometric assessment of bone are essential features of most studies of metabolic bone diseases and their treatments. These methodologies were developed to assess coupled remodeling, focusing primarily on osteoblasts and osteoclasts, the anabolic and catabolic rates of these cells, and structural features of mature bone. Research studies on bone healing and the development of new therapeutic approaches for the enhancement of bone repair also require a comprehensive understanding of the basic cellular and tissue level mechanisms that underlie these processes. However, the histological methods developed for metabolic bone disease studies are not completely suitable for studies of bone repair because they are based on assumptions that there is little variation in tissue composition within a sample of bone and not generally designed to quantify other types of tissues, such as cartilage, that contribute to bone healing. These techniques also do not provide tissue-based structural measurements that are relatable to the specific types of biomechanical and radiographic structural assessments that are used to determine rates of bone healing. These deficiencies in current histological approaches therefore point to the need to establish standardized criteria for the histomorphometric assessments that are specifically adapted for the study of bone repair in models of fracture healing and bone regeneration. In this Perspective, we outline what we believe to be the specific structural, tissue. and cellular aspects that need to be addressed to establish these standardized criteria for the histomorphometric assessment of bone repair. We present the specific technical considerations that need to be addressed to appropriately sample repair tissues to obtain statistically meaningful results and suggest specific procedures and definitions of nomenclatures for the application of this technology to bone repair. Finally, we present how aspects of histomorphometric measurements of bone repair can be related to biomechanical and radiographic imaging properties that functionally define rates of bone healing, and thus, how these tools can be used to provide corroborating data. [source] On the self-weighted alternating trilinear decomposition algorithm,the property of being insensitive to excess factors used in calculationJOURNAL OF CHEMOMETRICS, Issue 5 2001Zeng-Ping Chen Abstract PARAFAC is well known as an iterative trilinear decomposition method. In practice, an accurate estimation of the number of underlying factors is required; otherwise it is difficult to guarantee the chemical meaning of the results obtained. The absence of a versatile chemometric method for factor estimation has often caused problems for analysts. With the advent of ATLD followed by SWATLD, the above relatively strict constraint can be relaxed. Experiments have shown that the profiles of the underlying factors can be extracted by ATLD (Wu et al., J. Chemometrics 1998; 12: 1) and SWATLD (Chen et al., Chemometrics Intell. Lab. Syst. 2000; 52: 75) as long as the number of factors used in calculation is no less than the number of actual factors. In other words, an overestimation of the number of factors will not affect the obtainment of chemically meaningful results by SWATLD and ATLD. In this paper the authors provide some simple mathematical explanations of this valuable property of SWATLD. Along with these explanations, some other properties of SWATLD as well as some guidelines for designing new trilinear decomposition methods are also discussed. Copyright © 2001 John Wiley & Sons, Ltd. [source] Evaluation of the Self-Heating Tendency of Vegetable Oils by Differential Scanning CalorimetryJOURNAL OF FORENSIC SCIENCES, Issue 6 2008Amélie Baylon M.S. Abstract:, The evaluation of the self-heating propensity of a vegetable (or animal) oil may be of significant importance during the investigation of a fire. Unfortunately, iodine value and gas chromatographic-mass spectrometric analysis do not lead to meaningful results in this regard. To the contrary, differential scanning calorimetry (DSC), which does not measure the chemical composition of the oil, but rather its thermodynamic behavior, produces valuable results. After a thorough literature review on the autooxidation of vegetable oils, several oils with different self-heating tendencies were analyzed using a Mettler-Toledo differential scanning calorimeter DSC 25 between 40°C and 500°C. Analyses were carried out both under air and nitrogen atmosphere to identify the phenomena due to autooxidation reactions. Using DSC, it was possible to observe the induction period of the oil (when available), the three different exothermic events, and the autoignition temperature (relatively independent of the oil type). [source] Use of proteomics for the identification of novel drug targets in brain diseasesJOURNAL OF NEUROCHEMISTRY, Issue 2 2007Jose A. Morón Abstract In spite of the rapid advances in the development of the new proteomic technologies, there are, to date, relatively fewer studies aiming to explore the neuronal proteome. One of the reasons is the complexity of the brain, which presents high cellular heterogeneity and a unique subcellular compartmentalization. Therefore, tissue fractionation of the brain to enrich proteins of interest will reduce the complexity of the proteomics approach leading to the production of manageable and meaningful results. In this review, general considerations and strategies of proteomics, the advantages and challenges to exploring the neuronal proteome are described and summarized. In addition, this article presents an overview of recent advances of proteomic technologies and shows that proteomics can serve as a valuable tool to globally explore the changes in brain proteome during various disease states. Understanding the molecular basis of brain function will be extremely useful in identifying novel targets for the treatment of brain diseases. [source] Measurement of the parameters of the mass transfer kinetics in high performance liquid chromatographyJOURNAL OF SEPARATION SCIENCE, JSS, Issue 3-4 2003Kanji Miyabe Abstract Fundamental studies of the mass transfer kinetics are as essential as those of the retention equilibrium for a detailed understanding of the characteristics and the mechanisms of chromatographic separations. The acquisition of a large amount of reliable experimental data and of meaningful results is necessary for any further progress of our knowledge of kinetics. The main goal of this review is to provide information on the methods used to perform accurate measurements and on the data analysis procedures used for deriving the kinetic parameters characterizing mass transfer in HPLC. First, the general characteristics of several methods of determination of some kinetic parameters are briefly reviewed. Secondly, we give detailed explanations of the experimental conditions of the pulse on a plateau method (i.e., elution chromatography on a plateau of finite concentration or pulse response method) and of the data analysis procedures based on moment analysis. Thirdly, we explain some important requirements for the acquisition of appropriate experimental data and discuss corrections to be applied when deriving several kinetic parameters. Fourthly, we discuss the accuracy of the kinetic parameters derived from the pulse on a plateau method and from moment analysis. Finally, some results concerning the mass transfer kinetics in RPLC systems are demonstrated as examples. [source] Skin reactivity to histamine and to allergens in unselected 9-year-old children living in Poland and ItalyPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 3 2003Roberto Ronchetti Several studies have shown a higher prevalence of positive skin-prick tests to airborne allergens in Western than in Eastern European countries. We have recently reported that skin histamine reactivity significantly increased in Italy over the past 15 years. Population differences in skin histamine reactivity could, at least in part, explain the reported differences in positive allergen skin tests. To test this hypothesis we compared histamine skin reactivity and the prevalence of allergen positive skin-prick tests in a sample of Italian and Polish schoolchildren. A total of 336 unselected 9-year-old-schoolchildren (198 in Italy and 138 in Poland) underwent skin-prick tests with three different histamine concentrations (10, 1 and 0.2 mg/ml) and with a panel of common airborne allergens according to the ISAAC protocol, phase two. Mean wheals elicited by skin-prick tests with the three serial concentrations of histamine were significantly larger (p < 0.001) and shifted more toward higher values (p < 0.001) in Italian than in Polish children. The differences were greater for the intermediate histamine concentration tested (1 mg/ml) than for the highest concentration (10 mg/ml). Skin-prick tests for airborne allergens were more frequently positive in Italian children: wheals ,,3 mm induced by any allergen [odds ratio (OR) 1.69; confidence interval (CI) 0.98,2.92] by Dermatophagoides pteronyssinus (OR 1.92; CI 0.97,3.80) and by D. farinae (OR 3.15; CI 1.16,8.63). Labeling as positive allergen wheal reactions half the size of the 10 mg/ml histamine wheal or larger reduced but did not abolish the Italian,Polish differences. The significantly higher skin histamine reactivity observed in Italian children could help to explain why allergen skin-test reactions differ in the East and West European populations. Moreover, differences in nonallergen-specific factors among populations should be considered in the interpretation of skin test results (e.g. cut-off points). To obtain meaningful results, epidemiological studies of allergies should include serial histamine dilutions. [source] Change of the unbinding mechanism upon a mutation: A molecular dynamics study of an antibody,hapten complexPROTEIN SCIENCE, Issue 10 2005Raffaele Curcio Abstract We study forced unbinding of fluorescein from the wild type (WT) and a mutant [H(H58)A] of the single-chain variable-fragment (scFv) anti-fluorescein antibody FITC-E2 by molecular dynamics simulations using various pulling techniques. A large number of long simulations were needed to obtain statistically meaningful results as both the wild type and the H(H58)A mutant unbinding occurs through multiple pathways, often with metastable intermediates. For the wild type, the rate-limiting step in the unbinding process corresponds to the breaking of the non-native interactions characteristic of a specific intermediate. The H(H58)A mutation disfavors the occurrence of this intermediate. Two events where the hapten partially unbinds in the absence of pulling force are observed in extensive equilibrium simulations of the wild type, and their analysis indicates that forced unbinding and spontaneous unbinding proceed along similar pathways. The different unbinding mechanisms observed in the simulations suggest a possible reason for the difference in the experimental off-rate between the two antibodies. We predict mutations that are expected to modulate the occurrence of the unbinding intermediate. For two such new mutants [H(H58)A and S(H52)A], our predictions are validated in silico by additional simulations. The accompanying paper in this issue by Honegger et al. reports the X-ray structure of FITC-E2 with a derivative of fluorescein, which was used as the starting conformation for the work presented here. [source] | |||||||||||||||||||