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Search Results: 1 - 10 of 133164 matches for " David W. Redding "
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Phylogenetically-Informed Priorities for Amphibian Conservation
Nick J. B. Isaac, David W. Redding, Helen M. Meredith, Kamran Safi
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043912
Abstract: The amphibian decline and extinction crisis demands urgent action to prevent further large numbers of species extinctions. Lists of priority species for conservation, based on a combination of species’ threat status and unique contribution to phylogenetic diversity, are one tool for the direction and catalyzation of conservation action. We describe the construction of a near-complete species-level phylogeny of 5713 amphibian species, which we use to create a list of evolutionarily distinct and globally endangered species (EDGE list) for the entire class Amphibia. We present sensitivity analyses to test the robustness of our priority list to uncertainty in species’ phylogenetic position and threat status. We find that both sources of uncertainty have only minor impacts on our ‘top 100‘ list of priority species, indicating the robustness of the approach. By contrast, our analyses suggest that a large number of Data Deficient species are likely to be high priorities for conservation action from the perspective of their contribution to the evolutionary history.
Characterization of an Ancient Lepidopteran Lateral Gene Transfer
David Wheeler, Amanda J. Redding, John H. Werren
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0059262
Abstract: Bacteria to eukaryote lateral gene transfers (LGT) are an important potential source of material for the evolution of novel genetic traits. The explosion in the number of newly sequenced genomes provides opportunities to identify and characterize examples of these lateral gene transfer events, and to assess their role in the evolution of new genes. In this paper, we describe an ancient lepidopteran LGT of a glycosyl hydrolase family 31 gene (GH31) from an Enterococcus bacteria. PCR amplification between the LGT and a flanking insect gene confirmed that the GH31 was integrated into the Bombyx mori genome and was not a result of an assembly error. Database searches in combination with degenerate PCR on a panel of 7 lepidopteran families confirmed that the GH31 LGT event occurred deep within the Order approximately 65–145 million years ago. The most basal species in which the LGT was found is Plutella xylostella (superfamily: Yponomeutoidea). Array data from Bombyx mori shows that GH31 is expressed, and low dN/dS ratios indicates the LGT coding sequence is under strong stabilizing selection. These findings provide further support for the proposition that bacterial LGTs are relatively common in insects and likely to be an underappreciated source of adaptive genetic material.
Hegel, Idealism and God: Philosophy as the Self-Correcting Appropriation of the Norms of Life and Thought
Paul Redding
Cosmos and History : the Journal of Natural and Social Philosophy , 2007,
Abstract: Can Hegel, a philosopher who claims that philosophy lsquo;has no other object but God and so is essentially rational theologyrsquo;, ever be taken as anything emother than/em a religious philosopher with little to say to any philosophical project that identifies itself as emsecular/em?nbsp; If the valuable substantive insights found in the detail of Hegelrsquo;s philosophy are to be rescued for a secular philosophy, then, it is commonly presupposed, some type of global reinterpretation of the enframing idealistic framework is required. In this essay, this assumption is challenged. br /br /Kantrsquo;s interpretation of space and time as a response to Newtonrsquo;s theologically based spatio-temporal emrealism/em is taken as a model of what it is to be a Kantian emidealist/em about God and the self. In turn, Hegelrsquo;s philosophy is taken as a development of this approach that overcomes the limitations of Kantrsquo;s formal approach. Hegelrsquo;s major contribution to Kantrsquo;s revolutionary transformation of the task of philosophy is, it is argued, his recognitive conception of lsquo;spiritrsquo;. While this has been widely appreciated with regard to the relations between lsquo;subjectiversquo; and lsquo;objectiversquo; spirit, it is suggested that a fuller understanding of the nature of Hegelrsquo;s emabsolute/em idealism requires a proper understanding of how this approach also applies to the domain of lsquo;absolute spiritrsquo;. br /br /
Quantum Electrodynamic Modeling of Silicon-Based Active Devices
Shouyuan Shi,Brandon Redding,Tim Creazzo,Elton Marchena,Dennis W. Prather
Advances in Optical Technologies , 2008, DOI: 10.1155/2008/615393
Abstract: We propose a time-domain analysis of an active medium based on a coupled quantum mechanical and electromagnetic model to accurately simulate the dynamics of silicon-based photonic devices. To fully account for the nonlinearity of an active medium, the rate equations of a four-level atomic system are introduced into the electromagnetic polarization vector. With these auxiliary differential equations, we solve the time evolution of the electromagnetic waves and atomic population densities using the FDTD method. The developed simulation approach has been used to model light amplification and amplified spontaneous emission in silicon nanocrystals, as well as the lasing dynamics in a novel photonic crystal-based silicon microcavity.
Mutated elements of a complex promoter (Amh) can help to demonstrate the role of certain elements in controlling differential gene expression  [PDF]
David W. Dresser
American Journal of Molecular Biology (AJMB) , 2012, DOI: 10.4236/ajmb.2012.24036
Abstract: Amh is a single copy gene which is expressed in different ways during mammalian development. Several potential promoter elements have been identified using physiological experimentation and on the basis of interspecific sequence comparison. The role of putative promoter elements in controlling gene expression has been investigated by many workers over the last two decades and here by individually mutating each element. Expression was measured in vitro in cells of Sertoli descent by flowcytometry using EGFP as a reporter gene. Three lines of murine cells were used; pre- and post-pubertal Sertoli and granulosa cells. Differences between the three lines of cells, support the view that differentiation in this in vitro model system is likely to be at the level of available transcription factors at given points in development.
Interaction between the Wilms tumour factor-1 element in the promoter of Amh and a downstream enhancer is required for a strong expression of the gene in pre-pubertal sertoli cells  [PDF]
David W. Dresser
American Journal of Molecular Biology (AJMB) , 2013, DOI: 10.4236/ajmb.2013.33022
Abstract:

Amh (anti-Müllerian hormone) is a single copy gene which is expressed strongly in Sertoli cells in the foetal testis and participates in the onset of sexual differentiation. Its promoter driving the expression of a reporter gene (d2EGFP) has been used to analyse the role of certain defined putative elements and a downstream enhancer element in gene expression. These experiments were carried out in vitro using a line of pre-pubertal mouse Sertoli cells, transienly transfected with circular DNA constructs with variously mutated promoter elements. A downstream enhancer element, situated immediately 3’ of the polyadenylation (PA) signal for Amh, has been inserted in an equivalent position in the d2EGFP construct. When the Amh promoter is unmodified, the downstream enhancer (DE) is positively associated with a large increase in EGFP expression. This is at least partly the consequence of an increased rate of expression by individual cells. Experiments using variously truncated Amh promoters indicate that an upstream region (-214 to -336) may play a minor role in facilitating enhancement. However mutation of the Wilms tumour factor-1 element, situated between the tata box and the start of translation, results in an almost complete suppression of enhancement.

Marketing Accountability: Defining Expectations and Measuring Outcomes  [PDF]
David W. Stewart
Open Journal of Business and Management (OJBM) , 2014, DOI: 10.4236/ojbm.2014.23019
Abstract: This paper calls for work that focuses on the relationships of marketing activities and outcomes and measures of the financial performance of the firm. More specifically, the paper suggests the need to link marketing outcomes to the cash flow of the firm and the business model that generates the cash flow. The paper also calls for greater alignment of measures of marketing accountability with expectations and responsibilities of the marketing organization.
The Transcription Factors GATA-1 and GATA-4 Have Opposite Effects on DNA Expression Driven by an Amh Promoter  [PDF]
David W. Dresser
American Journal of Molecular Biology (AJMB) , 2014, DOI: 10.4236/ajmb.2014.43016
Abstract:

An Amh promoter driving expression of a reporter gene (d2EGFP) has been used to analyze the role of two specific promoter transcription factor binding elements. In addition a downstream (3’) enhancer (DE) was also investigated. The transcription factors GATA-1 and GATA-4 had opposite effects, the former being incremental and the latter decremental. The quantitative balance between these two factors may provide a degree of control over the level of gene expression.

Optimal Consumption under Uncertainties: Random Horizon Stochastic Dynamic Roy’s Identity and Slutsky Equation  [PDF]
David W. K. Yeung
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.52028
Abstract:

This paper extends Slutsky’s classic work on consumer theory to a random horizon stochastic dynamic framework in which the consumer has an inter-temporal planning horizon with uncertainties in future incomes and life span. Utility maximization leading to a set of ordinary wealth-dependent demand functions is performed. A dual problem is set up to derive the wealth compensated demand functions. This represents the first time that wealth-dependent ordinary demand functions and wealth compensated demand functions are obtained under these uncertainties. The corresponding Roy’s identity relationships and a set of random horizon stochastic dynamic Slutsky equations are then derived. The extension incorporates realistic characteristics in consumer theory and advances the conventional microeconomic study on consumption to a more realistic optimal control framework.

Super-Enhancement and Control of Amh Expression  [PDF]
David W. Dresser
American Journal of Molecular Biology (AJMB) , 2016, DOI: 10.4236/ajmb.2016.63012
Abstract: In previous work it was shown that mutation of site 1 in the downstream enhancer sequence (DE) led to ablation of enhancement. Mutation of the Wilms tumour factor element (Wt), situated in the Amh promoter between the tata box and the start of translation (TSS), also led to ablation of enhancement. This suggested that these sites may be the anchor points for a specific duplex factor bridging remote DNA elements to the promoter. Mutation analysis of the DNA sequence between sections 1 and 2 of DE was carried out by site directed mutagenesis. It is reported here that site 4 lying between DE1 and DE2, plays a key role in controlling the level of enhancement.
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