121,875 research outputs found
Probing possible left-and right-handed polynucleotide helical conformations from n-h plots. Glycosyl and backbone torsional variation on handedness of helix
No full textThe helical parameters n (the number of nucleotide residues per turn) and h (the residue height along the helical axis) have been evaluated for single stranded polynucleotide chains and are found to be dependent on the nature of the sugar ring pucker and the nucleotide backbone torsions. The n-h plot reveals that both the familiar right-handed and possible types of left-handed helical conformations fall within the same broad domain, thus conformation "transitions" from right-handed to left-handed helix and vice versa affect only slightly the backbone torsions. The glycosyl angle apparently suffers the greatest change in the reversal of the helix sense. The normal anti (χ ' 0-80°) found in right-handed polynucleotides increases to the "high anti" (χ '125°) as exemplified by the Ikehara polymers: synthetic poly (As) and poly (Uo) where the monomeric cyclonucleoside units are fixed in the high anti χ by a covalent linkage between the base C8/C6 and sugar C2' atoms. Conformational energy calculations [Fujii and Tomita, Nucl. Acids Res. 3, 1973 (1976)] on model compounds of Ikehara polymers have shown that the backbone conformations of the left-handed polynucleotides are in silimar conformational domains as the known right-handed polynucleotides, and are in agreement with the work of Yathindra and Sundaralingam [Nucl. Acids Res. 3, 729 (1976)]. These studies indicate that the molecular mechanics of untwisting a helix, leading eventually to a change in helical sense, may involve a combined process of adjusting the glycosyl angle, the pseudorotation phase angle, and the backbone torsions, that is, helix untwisting perhaps involves synchronous rotations around the glycosyl and backbone bonds. In nucleic acids the left-handed helical conformations are as a rule not favored because the high anti χ is not particularly favored. But under certain situations the left-handed base stack and left-handed helical backbone may occur, especially in short segments around the loop and folded regions of the tertiary structure
Conformational studies on guanosine nucleotides and polynucleotides. The effect of the base on the glycosyl and backbone conformations
No full textPotential energy calculations have been carried out on guanosine 5'-monophosphate and guanosine 3',5'-diphosphate by simultaneous variation of the rotation angles X and Ψ to assess the influence of the base on the glycosyl and the sugar-phosphate backbone conformations and their possible interdependence. The results obtained predict that guanine containing nucleotides tend to favor the syn glycosyl conformation in sharp contrast to the anti conformation found for adenine and the common pyrimidine nucleotides. This characteristic behavior of guanine nucleotides is largely a result of increased non-bonded van der Waals' and electrostatic attractive interactions between the 5'-phosphate and the amino group of the base. As seen previously [N. Yathindra and M. Sundaralingam, Biopolymers, 12, 297 (1973)] changes in the glycosyl conformation mainly affects the C(4')-C(5') bond rotations of the backbone. The most favored (χ ,ψ ) conformer corresponding to the global minimum both in 5'-GMP and 3',5'-GDP is syn-gg, (190°,80°) for C(2')-endo rings and (180°,50°) for C(3')-endo rings. It is noteworthy that the syn angle is different from the usually observed range of 210-260°. The next significant minimum in the (χ ,ψ ) energy surface corresponds to the syn-gt conformational combination (the syn angle now in the normal range), indicating that the occurrence of the normal syn conformer induces a distortion in the backbone c(4')-c(5') bond conformation from the preferred gg. These studies reveal the significant influence of the base not only on the glycosyl conformation but also on the backbone conformations of polynucleotides
Analysis of the possible helical structures of nucleic acids and polynucleotides. Application of (n-h) plots.
No full textThe two helical parameters n and h where n is the number of nucleotide residues per turn and h is the height per nucleotide residue have been evalu-ated for single stranded helical polynucleotide chains comprising C(3') endo and C(2') endo class of nucleotides. The helical parameters are found to be especially sensitive to the C(U')-C(3') (sugar pucker) and the C(l*')~C(5') torsions. The (n-h) plots display only one important helix forming domain for each class of nucleotides characterized by the sugar pucker and the C{U')-C(5') torsion. A correlation between the (n-h) plots and the known RNA (A,A1) and DHA (A,B,C) helical forms has been established. It is found that all forms of helices except the C-DNA possess a favorable combination of P-0 torsions. The analysis of the (n-h) plots suggests that C-DNA can have a conformation very similar to B-DNA. Although the (n-h) plots predict the stereochemical possibility of both right-handed and left-handed helices, nucleic acids apparently prefer right-handed conformation because of th
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The vanishing author in computer-generated works: a critical analysis of recent Australian case law
No full textAbstract
The use of software is ubiquitous in the creation of many copyright works, yet the requirement in copyright law that every work have a human author who engages in independent intellectual effort means that its use may prevent copyright subsistence. Several recent Australian cases have refocused attention on authorship as an essential criterion of copyright subsistence, and these cases suggest that much computer-produced output may be authorless and thus lack copyright protection. This article, the first in a two-part series, analyses how each case deals with the question of authorship of computer-produced works and why the use of software diminishes copyright protection for a significant number of computer-generated works. The article critiques the application of conventional notions of human authorship developed in the pre-computer age to modern productions and suggests alternative approaches to authorship that satisfy both the major objectives of copyright policy and the need to adapt to the computer age. The article argues that, without a broader judicial approach to authorship of computer-generated works, Parliament must remedy the lacuna in protection for these ‘authorless’ works. Possible solutions for reform are suggested. In a forthcoming article, the author comprehensively examines those reform proposals
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Dissipative Range Scaling of Higher Order Structure Functions for Velocity and Passive Scalars
No full textDifferently to Kolmogorov's second similarity hypothesis, we find that the 2n-th order velocity and scalar structure functions scale with n-th order moment of the energy dissipation and the scalar dissipation, respectively. The origins of this scaling are analyzed by the transport equations of the fourth order velocity and scalar increment moments and by direct numerical simulations
Fast implementation of iterative adaptive approach for wideband unambiguous radar detection
No full textAccepted author manuscriptMicrowave Sensing, Signals & System
Ratio of n-6/n-3 in the diets of beef cattle
No full textEffects of feeding heat-treated canola (C), soybean (S) and flax (F) or mixtures on growth and slaughter characteristics, taste and fatty acid (FA) composition of beef tissue were investigated using 128 crossbred steers to determine the potential of improving the nutritional quality of beef for humans. For Trial 1 (48 steers), dietary treatments were: roasted C, extruded C, roasted S, extruded S, roasted F and extruded F. For Trial 2 (80 steers), the dietary treatments were: S:F (1:1), S:C (1:1), C:F (1:1) and S:F:C (1:1:1), and the oilseeds were processed either by roasting or extruding before mixing. Soybean meal and soybean oil were used to give equivalent lipid and protein contents to each experimental diet. The basal diet consisted of grass silage, barley grain, vitamins and minerals. Steers were fed for a minimum of 100d then slaughtered at a uniform degree of finish. Growth and slaughter characteristics of the steers were only slightly affected by dietary treatment in that the soybean-fed steers consumed more feed and had a higher average daily gain than the canola or flax-fed animals in Trial 1. There was no difference in taste panel parameters for any of the treatments. Inclusion of flax in the diet increased the total n-3 content of meat. Similar results were found for canola and C18:1n-9 although this was not the case for soybean and the n-6 FA. For the n-6 FA in the PL and neutral lipid fractions of the meat samples, levels were correlated with high dietary levels of n-6 or n-9 with low levels of n-3 while for the n-3 FA, levels were correlated with high dietary n-3 levels and low n-6 levels. Oilseed processing method did not have an effect on any fatty acid levels. It is possible to modify the FA composition of beef meat toward a healthier profile by including heat-treated oilseeds in the diet to influence the degree of lipid metabolism in the rumen.ID: S0377840111004007; M3: Article; Accession Number: S0377840111004007; Author: M.A. McNiven (a, ⁎); Author: J.L. Duynisveld (b); Author: T. Turner (a); Author: A.W. Mitchell (a); Affiliation: Department of Health Management, Atlantic Veterinary College, University of PEI, Charlottetown, PEI, Canada C1A 4P3; Affiliation: Agriculture and Agri-Food Canada, Nappan, NS, Canada B0L 1C0; Keyword: Oilseeds; Keyword: Roasted; Keyword: Extruded; Keyword: Fatty acids; Keyword: Healthy fat; Number of Pages: 11; Language: English
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