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Search Results: 1 - 10 of 472834 matches for " William A; "
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Intergenic subset organization within a set of geographically-defined viral sequences from the 2009 H1N1 influenza A pandemic  [PDF]
William A. Thompson, Joel K. Weltman
American Journal of Molecular Biology (AJMB) , 2012, DOI: 10.4236/ajmb.2012.21004
Abstract: We report a bioinformatic analysis of the datasets of sequences of all ten genes from the 2009 H1N1 influenza A pandemic in the state of Wisconsin. The gene with the greatest summed information entropy was found to be the hemagglutinin (HA) gene. Based upon the viral ID identifier of the HA gene sequence, the sequences of all of the genes were sorted into two subsets, depending upon whether the nucleotide occupying the position of maximum entropy, position 658 of the HA sequence, was either A or U. It was found that the information entropy (H) distributions of subsets differed significantly from each other, from H distributions of randomly generated subsets and from the H distributions of the complete datasets of each gene. Mutual information (MI) values facilitated identification of nine nucleotide positions, distributed over seven of the influenza genes, at which the nucleotide subsets were disjoint, or almost disjoint. Nucleotide frequencies at these nine positions were used to compute mutual information values that subsequently served as weighting factors for edges in a graph net-work. Seven of the nucleotide positions in the graph network are sites of synonymous mutations. Three of these sites of synonymous mutation are within a single gene, the M1 gene, which occupied the position of greatest graph centrality. It is proposed that these bioinformatic and network graph results may reflect alterations in M1-mediated viral packaging and exteriorization, known to be susceptible to synonymous mutations.
Speed kills: Highly relativistic spaceflight would be fatal for passengers and instruments  [PDF]
William A. Edelstein, Arthur D. Edelstein
Natural Science (NS) , 2012, DOI: 10.4236/ns.2012.410099
Abstract: Highly relativistic speeds are desirable for interstellar travel. Relativistic time dilation would reduce the subjective duration of the trip for the travelers, so that they can cover galaxy-scale distances in a reasonable amount of personal time. Unfortunately, as spaceship velocities approach the speed of light, interstellar hydrogen H, although only present at a density of approximately 1.8 atoms/cm3, turns into intense radiation that would quickly kill passengers and destroy electronic instrumentation. In addition, the energy loss of ionizing radiation passing through the ship’s hull represents an increasing heat load that necessitates large expenditures of energy to cool the ship. Stopping or diverting this flux, either with material or electromagnetic shields, is a daunting problem. Going slow to avoid severe H irradiation sets an upper speed limit of v ~ 0.5 c. This velocity only gives a time dilation factor of about 15%, which would not substantially assist galaxy-scale voyages. Diffuse interstellar H atoms are the ultimate cosmic space mines and represent a formidable obstacle to interstellar travel.
Investigating Physiological and Morphological Mechanisms of Drought Tolerance in Wheat (Triticum aestivum L.) Lines with 1RS Translocation  [PDF]
David Karki, William Wyant III, William A. Berzonsky, Karl D. Glover
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.513207
Abstract:

Rye (Secale cereale L.) chromosome translocation is reported to enhance yield attributes in common wheat (Triticum aestivum L.). We used 1RS translocations within the spring wheat cultivar “Pavon76” to measure and identify the translocation that is suitable to withstand moisture stress conditions without significant loss in yield potential. Four lines were grown under two water regimes in greenhouse environment in 2011 and 2012. The rye translocation increased root and shoot biomass in some cases, reduced plant height, and delayed maturity in some cases. The 1RS.1BL translocation produced the highest grain yield associated with the lowest root and shoot biomass under both well watered and water stressed conditions. Root and shoot biomass were recorded the highest for 1RS.1AL under well watered condition. However it produced the least biomass for both traits under water stressed conditions. In most cases, lines were not statistically differentiated for seminal root angle, abscisic acid concentration, water use efficiency, and grain yield. Results from our study show that the 1RS.1BL translocation is more suited to produce high grain yield under moisture limiting conditions.

Epigenetic Mechanisms of Genomic Imprinting: Common Themes in the Regulation of Imprinted Regions in Mammals, Plants, and Insects
William A. MacDonald
Genetics Research International , 2012, DOI: 10.1155/2012/585024
Abstract: Genomic imprinting is a form of epigenetic inheritance whereby the regulation of a gene or chromosomal region is dependent on the sex of the transmitting parent. During gametogenesis, imprinted regions of DNA are differentially marked in accordance to the sex of the parent, resulting in parent-specific expression. While mice are the primary research model used to study genomic imprinting, imprinted regions have been described in a broad variety of organisms, including other mammals, plants, and insects. Each of these organisms employs multiple, interrelated, epigenetic mechanisms to maintain parent-specific expression. While imprinted genes and imprint control regions are often species and locus-specific, the same suites of epigenetic mechanisms are often used to achieve imprinted expression. This review examines some examples of the epigenetic mechanisms responsible for genomic imprinting in mammals, plants, and insects. 1. Introduction Epigenetic regulation of the genome is a critical facet of development. Epigenetic control of gene expression allows heritable changes in gene expression without the need for alterations in DNA sequence. This is achieved through the recruitment of molecular processes that assist transcription, block transcription, or degrade existing transcripts. Genomic imprinting is an epigenetic process that marks DNA in a sex-dependent manner, resulting in the differential expression of a gene depending on its parent of origin. Achieving an imprint requires establishing meiotically stable male and female imprints during gametogenesis and maintaining the imprinted state through DNA replication in the somatic cells of the embryo. Erasure of the preceding generation’s imprint occurs in the germ line, followed by imprint reestablishment, in accordance with the sex of the organism. Each step in this imprinting process requires epigenetic marks to be interpreted by the genome and acted upon accordingly to result in parent-specific gene expression. Genomic imprinting has been widely reported in eutherian mammals and marsupials [1–3]. Mice comprise the primary research model organism for the study of genomic imprinting. Approximately one hundred imprinted genes have been identified in mice with many more predicted to be present [2, 4]. This review considers imprinting to include chromosomal domains that direct imprinted epigenetic regulation, even if endogenous transcriptional units have yet to be identified as imprinting targets. Many imprinted genes in mice are developmentally important, linked to the formation of the placenta, or
Prodrugs for Gene-Directed Enzyme-Prodrug Therapy (Suicide Gene Therapy)
William A. Denny
Journal of Biomedicine and Biotechnology , 2003, DOI: 10.1155/s1110724303209098
Abstract: This review focuses on the prodrugs used in suicide gene therapy. These prodrugs need to satisfy a number of criteria. They must be efficient and selective substrates for the activating enzyme, and be metabolized to potent cytotoxins preferably able to kill cells at all stages of the cell cycle. Both prodrugs and their activated species should have good distributive properties, so that the resulting bystander effects can maximize the effectiveness of the therapy, since gene transduction efficiencies are generally low. A total of 42 prodrugs explored for use in suicide gene therapy with 12 different enzymes are discussed, particularly in terms of their physiocochemical properties. An important parameter in determining bystander effects generated by passive diffusion is the lipophilicity of the activated form, a property conveniently compared by diffusion coefficients (log P for nonionizable compounds and log D7 for compounds containing an ionizable centre). Many of the early antimetabolite-based prodrugs provide very polar activated forms that have limited abilities to diffuse across cell membranes, and rely on gap junctions between cells for their bystander effects. Several later studies have shown that more lipophilic, neutral compounds have superior diffusion-based bystander effects. Prodrugs of DNA alkylating agents, that are less cell cycle-specific than antimetabolites and more effective against noncycling tumor cells, appear in general to be more active prodrugs, requiring less prolonged dosing schedules to be effective. It is expected that continued studies to optimize the bystander effects and other properties of prodrugs and the activated species they generate will contribute to improvements in the effectiveness of suicide gene therapy.
Seymour Benzer 1921–2007 The Man Who Took Us from Genes to Behaviour
William A. Harris
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0060041
Abstract:
Supramolecular Hydrogen-Bond Motifs in Chiral and Racemic Molecular Salts: A Comparison of (S)-2-Methyl Piperizinium Hydrogen Phosphite Monohydrate, C5H14N2·HPO3·H2O and (R,S)-2-Methyl Piperizinium Hydrogen Phosphite 2.23 Hydrate, C5H14N2·HPO3·2.23H2O
William T. A. Harrison
Crystals , 2011, DOI: 10.3390/cryst1040236
Abstract: The crystal structures of C 5H 14N 2·HPO 3·H 2O ( 1) and C 5H 14N 2·HPO 3·2.23H 2O ( 2) are described and compared. Compound 1 contains homochiral ( S)-2-methyl piperizinium cations, hydrogen phosphite ions and water molecules. The components are linked by N–H?O and O–H?O hydrogen bonds into a three-dimensional network. In compound 2, racemic ( R, S)-2-methyl piperizinium cations combine with the same anions and water molecules to generate a far more complex, high symmetry “supramolecular” structure, which features distinctive R 6 6(12) loops and helical C(2) chain hydrogen-bonding motifs involving the water molecules. Crystal data: 1 (C 5H 17N 2O 4P), M r = 200.18, orthorhombic, P2 12 12 1 (No. 19), Z = 4, a = 8.564 (5) ?, b = 9.593 (6) ?, c = 11.607 (6) ?, V = 953.6 (9) ? 3, R( F) = 0.066, wR( F 2) = 0.081. 2 (C 5H 19.47N 2O 5.24P), M r = 222.49, trigonal, (No. 148), Z = 18, a = 31.075 (2) ?, c = 6.1875 (4) ?, V = 5174.5 (6) ? 3, R( F) = 0.044, wR( F 2) = 0.107.
Self-Organized Complexity and Coherent Infomax from the Viewpoint of Jaynes’s Probability Theory
William A. Phillips
Information , 2012, DOI: 10.3390/info3010001
Abstract: This paper discusses concepts of self-organized complexity and the theory of Coherent Infomax in the light of Jaynes’s probability theory. Coherent Infomax, shows, in principle, how adaptively self-organized complexity can be preserved and improved by using probabilistic inference that is context-sensitive. It argues that neural systems do this by combining local reliability with flexible, holistic, context-sensitivity. Jaynes argued that the logic of probabilistic inference shows it to be based upon Bayesian and Maximum Entropy methods or special cases of them. He presented his probability theory as the logic of science; here it is considered as the logic of life. It is concluded that the theory of Coherent Infomax specifies a general objective for probabilistic inference, and that contextual interactions in neural systems perform functions required of the scientist within Jaynes’s theory.
Reabilita??o nomenclatural e taxon?mica de Virola bicuhyba (Schott) Warb. (Myristicaceae)
Rodrigues, William A;
Acta Botanica Brasilica , 1998, DOI: 10.1590/S0102-33061998000300006
Abstract: this note deals with thc rehabilitation of the myristicaceous virola bicuhyba (schott) warb., designation of lectotypes and sinonimization of both v oleífera (schott) a. c. smith and bicuiba oleífera (schott) de wilde.
Entrada no campo, aceita??o e natureza da participa??o nos estudos etnográficos com crian?as pequenas
Corsaro, William A.;
Educa??o & Sociedade , 2005, DOI: 10.1590/S0101-73302005000200008
Abstract: doing ethnographic research with young children involves a number of challenges as adults are perceived as powerful and controlling of children's lives. in this paper i review my comparative ethnographic research of preschool children in the united states and italy. the focus is on field entry, establishing participant status, and the collection of field notes and audiovisual data. i briefly review field entry procedures i employed in field sites in the united states and italy. i discuss how my data collection methods over time became gradually more open to children's direct input which is what i mean by "research with as opposed to on children". finally, using the research from modena, italy i discuss a longitudinal ethnography across key transition periods in children's lives. this ethnography involved my staying with and continuing to observe and interview the children as the entered first grade and throughout their five years of elementary school.
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