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Selected AbstractsPurification, characterization, cDNA cloning and nucleotide sequencing of a cellulase from the yellow-spotted longicorn beetle, Psacothea hilarisFEBS JOURNAL, Issue 16 2003Masahiro Sugimura A cellulase (endo-,-1,4-glucanase, EC 3.2.1.4) was purified from the gut of larvae of the yellow-spotted longicorn beetle Psacothea hilaris by acetone precipitation and elution from gels after native PAGE and SDS/PAGE with activity staining. The purified protein formed a single band, and the molecular mass was estimated to be 47 kDa. The purified cellulase degraded carboxymethylcellulose (CMC), insoluble cello-oligosaccharide (average degree of polymerization 34) and soluble cello-oligosaccharides longer than cellotriose, but not crystalline cellulose or cellobiose. The specific activity of the cellulase against CMC was 150 µmol·min,1·(mg protein),1. TLC analysis showed that the cellulase produces cellotriose and cellobiose from insoluble cello-oligosaccharides. However, a glucose assay linked with glucose oxidase detected a small amount of glucose, with a productivity of 0.072 µmol·min,1·(mg protein),1. The optimal pH of P. hilaris cellulase was 5.5, close to the pH in the midgut of P. hilaris larvae. The N-terminal amino-acid sequence of the purified P. hilaris cellulase was determined and a degenerate primer designed, which enabled a 975-bp cDNA clone containing a typical polyadenylation signal to be obtained by PCR and sequencing. The deduced amino-acid sequence of P. hilaris cellulase showed high homology to members of glycosyl hydrolase family 5 subfamily 2, and, in addition, a signature sequence for family 5 was found. Thus, this is the first report of a family 5 cellulase from arthropods. [source] Equal strain consolidation for stone columns reinforced foundationINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 15 2009Kang-He Xie Abstract Column consolidation and deformation are considered by assuming that the quantity of water flowing through the disturbed soil zone into the column is not equal to that flowing out from the column and the difference between them is equal to the volume change of the column. In addition, three patterns of distribution of the horizontal permeability of soil in the disturbed zone are also considered to account for the disturbance effect of columns construction on the surrounding soil. These three patterns include the constant distribution pattern (Pattern I), the linear distribution pattern (Pattern II) and the parabolic distribution pattern (Pattern III). By incorporating the aforementioned characteristics into the analyses, the governing equations containing two variables (i.e. the average excess pore-water pressures within the column and within the entire foundation at any depth) for the consolidation of a composite foundation are derived. The solutions of the governing equations are then obtained using a new initial condition derived from the assumption of equal strain and the equilibrium condition. On the basis of the solutions for excess pore-water pressures, the average degree of consolidation of a composite foundation is obtained and discussed. Finally, a comparison is made of some available solutions. Copyright © 2009 John Wiley & Sons, Ltd. [source] Consolidation analysis of a cross-anisotropic homogeneous elastic soil using a finite layer numerical methodINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 2 2004Guo-Xiong Mei Abstract This paper presents a finite layer procedure for Biot's consolidation analysis of layered soils using a cross-anisotropic elastic constitutive model. The program is first verified using published results. Then, using this program, the influences of cross-anisotropy on the immediate settlement, the final settlement, and the consolidation behaviour are investigated by changing one model parameter at one time. The results obtained using the cross-anisotropic elastic model are compared with results using an isotropic elastic model. It is found that the cross-anisotropy has very large influences on the immediate settlement, the final settlement, and the consolidation behaviour. Curves or tables of the immediate settlement coefficients, the final settlement coefficients, and the average degree of consolidation are obtained and presented in the paper. These curves or tables can be easily used to estimate the immediate settlement, the final settlement, and the consolidation settlement of a cross-anisotropic soil. Copyright © 2004 John Wiley & Sons, Ltd. [source] An algorithm for evaluating the ethics of a placebo-controlled trialINTERNATIONAL JOURNAL OF CANCER, Issue 5 2001Robert J. Amdur M.D. Abstract The purpose of this article is to clarify the decision points that are important to consider when evaluating the ethics of a placebo-controlled trial. The ethical requirements for research involving human subjects are reviewed, and the rationale for and potential problems with concomitant placebo control are explained. A series of case discussions are used to illustrate each decision point. The critical decision points in the evaluation of the ethics of a placebo-controlled trial are as follows: (i) Is placebo being used in place of standard therapy? (ii) Is standard therapy likely to be effective? (iii) Is the toxicity of standard therapy such that patients routinely refuse this treatment? (iv) Could the use of placebo result in severe suffering or irreversible harm? (v) Is the variability in the placebo response such that it is reasonable to consider other options for the control group? (vi) Would a reasonable person with an average degree of altruism and risk aversiveness agree to participate in this study? The algorithm presented in this article gives researchers and research monitors (such as Institutional Review Board members) the tools they need to evaluate the ethics of a study that uses concomitant placebo control. © 2001 Wiley-Liss, Inc. [source] The distribution,abundance (density) relationship: its form and causes in a tropical mammal order, PrimatesJOURNAL OF BIOGEOGRAPHY, Issue 4 2005A. H. Harcourt Abstract Aim, Across a wide variety of organisms, taxa with high local densities (abundance) have large geographical ranges (distributions). We use primatology's detailed knowledge of its taxon to investigate the form and causes of the relationship in, unusually for macroecological analysis, a tropical taxon. Location, Africa, Central and South America, Asia, Madagascar. Methods, To investigate the form of the density,range relationship, we regressed local density on geographical range size, and also on female body mass, because in the Primates, density correlates strongly with mass. To investigate the biological causes of the relationship, we related (1) abundance (density × range size) and (2) residuals from the density,range regression lines to various measures of (i) resource use, (ii) reproductive rate and (iii) potential specialization. All data are from the literature. Analyses were done at the level of species (n = 140), genera (n = 60) and families/subfamilies (n = 17). We present various levels of results, including for all data, after omission of outlier data, after correction for phylogenetic dependence, and after Bonferroni correction of probabilities for multiple comparisons. Results, Regarding the form of the relationship, Madagascar primates are clear outliers (high densities in small ranges). Among the remaining three realms, the relation of density to range is weak or non-existent at the level of species and genera. However, it is strong, tight and linear at the level of families/subfamilies (r2 = 0.6, F1,10 = 19, P < 0.01). Although among primates, density is very significantly related to mass, at no taxonomic level is range size related to body mass. Consequently, removing the effects of mass makes little to no difference to density,range results. Regarding the biology of the relationship, only traits indicative of specialization are associated with abundance (meaning numbers): rare taxa are more specialized than are abundant taxa. The association is largely via range size, not density. Across families, no traits correlate significantly with the density,range relationship, nor with deviations from it, despite the strength of the relationship at this taxonomic level. Main conclusions, We suggest that in macroecology, analysis at taxonomic levels deeper than that of the relatively ephemeral species can be appropriate. We argue that the several purely methodological explanations for the positive density,range size relationship in primates can be rejected. Of the various biological hypotheses, those having to do with specialization,generalization seem the only applicable ones. The fact that the relationship is entirely via range size, not via density, means that while we might have a biology of range size, we do not yet have one of the density,geographical range relationship. It is probably time to search for multivariate explanations, rather than univariate ones. However, we can for the first time, for at least primates, suggest that any association of abundance or range size with specialization is via the number of different subtaxa, not the average degree of specialization of each subtaxon. The implication for conservation is obvious. [source] On k -detour subgraphs of hypercubesJOURNAL OF GRAPH THEORY, Issue 1 2008Nana Arizumi Abstract A spanning subgraph G of a graph H is a k - detour subgraph of H if for each pair of vertices , the distance, , between x and y in G exceeds that in H by at most k. Such subgraphs sometimes also are called additive spanners. In this article, we study k -detour subgraphs of the n -dimensional cube, , with few edges or with moderate maximum degree. Let denote the minimum possible maximum degree of a k -detour subgraph of . The main result is that for every and On the other hand, for each fixed even and large n, there exists a k -detour subgraph of with average degree at most . © 2007 Wiley Periodicals, Inc. J Graph Theory 57: 55,64, 2008 [source] Genetic Analysis of the Latent Period of Stripe Rust in Wheat SeedlingsJOURNAL OF PHYTOPATHOLOGY, Issue 6 2004H. Dehghani Abstract Genetics of slow-rusting resistance to yellow rust (Puccinia striiformis f.sp. tritici) was studied by a half-diallel design using six wheat varieties, Tiritea (susceptible), Tancred, Kotare, Otane, Karamu, and Briscard. The parents and 15 F1 progenies were evaluated in the greenhouse by three pathotypes 7E18A,, 38E0A+, and 134E134A+. The latent period was measured as the number of days from inoculation to the appearance of the first pustule. For each pathotype a randomized complete block design was used and data were analysed by methods of Griffing and Hayman. The range of average degree of dominance was from complete dominance to over-dominance. Positive and negative degrees of dominance were observed for each pathotype that showed the reversal of dominance. Analysis of variance showed the importance of both additive and dominance effects in controlling the latent period. Broad-sense heritabilities were 0.99 and narrow-sense heritabilities ranged from 0.85 to 0.94. Briscard and Karamu for the pathotypes 38E0A+ and 134E134A+, Kotare for the pathotype 7E18A, and Tancred for the pathotype 38E0A+ had significant and positive general combining ability (GCA) (more resistance) for latent period. The crosses of Kotare with Tancred, Briscard and Karamu indicated the highest and positive specific combining ability (SCA) for the pathotype 7E18A,. Significant additive genetic component and moderate narrow-sense heritability indicate the possibility of improving for longer latent period of stripe rust in breeding programmes. [source] Synthesis of poly(4-vinylpyridine) by reverse atom transfer radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2007Gregory T. Lewis Abstract Controlled radical polymerization of 4-vinylpyridine (4VP) was achieved in a 50 vol % 1-methyl-2-pyrrolidone/water solvent mixture using a 2,2,-azobis(2,4-dimethylpentanitrile) initiator and a CuCl2/2,2,-bipyridine catalyst,ligand complex, for an initial monomer concentration of [M]0 = 2.32,3.24 M and a temperature range of 70,80 °C. Radical polymerization control was achieved at catalyst to initiator molar ratios in the range of 1.3:1 to 1.6:1. First-order kinetics of the rate of polymerization (with respect to the monomer), linear increase of the number,average degree of polymerization with monomer conversion, and a polydispersity index in the range of 1.29,1.35 were indicative of controlled radical polymerization. The highest number,average degree of polymerization of 247 (number,average molecular weight = 26,000 g/mol) was achieved at a temperature of 70 °C, [M]0 = 3.24 M and a catalyst to initiator molar ratio of 1.6:1. Over the temperature range studied (70,80 °C), the initiator efficiency increased from 50 to 64% whereas the apparent polymerization rate constant increased by about 60%. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5748,5758, 2007 [source] INULIN MILK BEVERAGES: SENSORY DIFFERENCES IN THICKNESS AND CREAMINESS USING R-INDEX ANALYSIS OF THE RANKING DATAJOURNAL OF SENSORY STUDIES, Issue 4 2007BEATRIZ VILLEGAS ABSTRACT Inulin has interesting functional properties, which are linked to the average degree of polymerization of its chains. The aims of this work were to explore the effect of adding different types of inulin (short chain, native and long chain) on the thickness and creaminess of milk-beverage model systems, and to explore the possibility of using each of the three types of inulin as a fat replacer in skimmed-milk beverages. Sensory ranking data were analyzed using the R-index. For the two lots of samples (whole milk and skimmed milk), all samples with added inulin were perceived as significantly thicker and creamier than the samples without inulin. The fat mimetic capacity of inulin depended not only on the chain length, but also on the concentration of added inulin. In order to obtain milk beverages with reduced fat content having similar thickness and creaminess than those perceived in whole milk beverages, it was necessary to add long-chain inulin at concentrations over 8%. PRACTICAL APPLICATIONS In most cases, inulin is added to different foods to supplement them in order to increase fiber ingestion, in amounts that vary between 3 and 6 g per portion, or to assure its bifidogenic nature, adding 3,8 g per portion. The results of this work provide information regarding the effects of inulin on the sensory characteristics of milk beverages, and show that applying the R-index analysis helped detect the small perceivable differences in thickness and creaminess among the samples tested, what will be of great use in formulating low-fat milk beverages. [source] Changes in inulin and soluble sugar concentration in artichokes (Cynara scolymus L.) during storageJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2010Gaëlle Leroy Abstract BACKGROUND: The artichoke (Cynara scolymus L.) accumulates about 50,70 g kg,1 of its fresh weight as inulin-type fructan. Inulin fermentation increases gas production and thereby provokes intestinal discomfort in some people. The present research focuses on the changes in carbohydrate composition occurring in artichoke heads during storage under different conditions (18 °C, 4 °C and 4 °C under polypropylene film packing). RESULTS: Carbohydrate content and composition were determined by anion-exchange high-performance liquid chromatography with pulsed amperometric detection. Storage time caused a decrease in inulin content and an average degree of polymerization, accompanied by an increase of free fructose and sucrose due to depolymerization of inulin. CONCLUSION: Higher-temperature storage and storage without packing induce strong carbohydrate changes. Thereby, eating stored artichoke leads to consumption of an inulin quantity that does not provoke unwanted symptoms related to gas production but sufficient to have a prebiotic effect. Copyright © 2010 Society of Chemical Industry [source] A fluorescence study on critical exponents during sol-gel phase transition in complex monomeric systemsMACROMOLECULAR SYMPOSIA, Issue 1 2003Demet Kaya Abstract Methyl methacrylate (MMA), ethyl methacrylate (EMA) and various combinations of MMA with EMA were used during FCC experiments. Pyrene (Py) was introduced as a fluorescence probe and fluorescence lifetimes from its decay traces were measured during sol-gel phase transitions. The fast transient fluorescence (FTRF) technique was used to study the critical exponents during sol-gel phase transition in free-radical crosslinking copolymerization (FCC). The results were interpreted in the view of percolation theory. The critical exponents of gel fraction, , and weight average degree of polymerization, , were measured near the point of gel effect and found to be around 0.37 ± 0.015 and 1.69 ± 0.05 in all systems studied respectively. [source] Mean-Square Radius of Gyration and Degree of Branching of Highly Branched Copolymers Resulting from the Copolymerization of AB2 With AB MonomersMACROMOLECULAR THEORY AND SIMULATIONS, Issue 8 2004Zhiping Zhou Abstract Summary: The evolution of the various structural units incorporated into hyperbranched polymers formed from the copolymerization of AB2 and AB monomers has been derived by the kinetic scheme. The degree of branching was calculated with a new definition given in this work. The degree of branching monotonously increased with increasing A group conversion (x) and the maximum value could reach 2r/(1,+,r)2, where r is the initial fraction of AB2 monomers in the total. Like the average degree of polymerization, the mean-square radius of gyration of the hyperbranched polymers increased moderately with A group conversion in the range x,<,0.9 and displayed an abrupt rise when the copolymerization neared completion. The characteristic ratio of the mean-square radius of gyration remained constant for the linear polymers. However, the hyperbranched polymers did not possess this character. In comparison with the linear polymerization, the weight average and z -average degree of polymerization increased due to the addition of the branched monomer units AB2 and the mean-square radius of gyration decreased quickly for the products of copolymerization. [source] Completely discontinuous organic/ inorganic hybrid nanocomposites by self-curing of nanobuilding blocks constructed from reactions of [HMe2SiOSiO1.5]8 with vinylcyclohexenePOLYMER INTERNATIONAL, Issue 11 2007Norihiro Takamura Abstract The reaction of 4-vinyl-1-cylcohexene with [HMe2SiOSiO1.5]8 provides tetra- and octa-2-cyclohexenylethyloctasilsesquioxanes. The tetrabifunctional [cyclohexenylethylMe2SiOSiO1.5]4 -[HMe2SiOSiO1.5]4 (average degree of functionalization) melts near 80 °C and can be cast and then cured (by thermal hydrosilylation) into transparent nanocomposite shapes. These materials, while not nanoporous, offer dielectric constants of 2.8,2.9 at 100 kHz to 3 MHz, and are air stable to temperatures , 400 °C. The resulting materials appear (by X-ray diffraction) to be partially ordered after curing. The octafunctional material also melts at low temperatures (ca 120 °C) and can be copolymerized with hydridosiloxanes to give similar materials with lower thermal stability. The synthesis and characterization of the starting materials is described, as well as thermal curing studies and properties characterization of the resultant nanocomposites. Copyright © 2007 Society of Chemical Industry [source] Rapid mixing of Gibbs sampling on graphs that are sparse on averageRANDOM STRUCTURES AND ALGORITHMS, Issue 2 2009Elchanan Mossel Abstract Gibbs sampling also known as Glauber dynamics is a popular technique for sampling high dimensional distributions defined on graphs. Of special interest is the behavior of Gibbs sampling on the Erd,s-Rényi random graph G(n,d/n), where each edge is chosen independently with probability d/n and d is fixed. While the average degree in G(n,d/n) is d(1 - o(1)), it contains many nodes of degree of order log n/log log n. The existence of nodes of almost logarithmic degrees implies that for many natural distributions defined on G(n,p) such as uniform coloring (with a constant number of colors) or the Ising model at any fixed inverse temperature ,, the mixing time of Gibbs sampling is at least n1+,(1/log log n). Recall that the Ising model with inverse temperature , defined on a graph G = (V,E) is the distribution over {±}Vgiven by . High degree nodes pose a technical challenge in proving polynomial time mixing of the dynamics for many models including the Ising model and coloring. Almost all known sufficient conditions in terms of , or number of colors needed for rapid mixing of Gibbs samplers are stated in terms of the maximum degree of the underlying graph. In this work, we show that for every d < , and the Ising model defined on G (n, d/n), there exists a ,d > 0, such that for all , < ,d with probability going to 1 as n ,,, the mixing time of the dynamics on G (n, d/n) is polynomial in n. Our results are the first polynomial time mixing results proven for a natural model on G (n, d/n) for d > 1 where the parameters of the model do not depend on n. They also provide a rare example where one can prove a polynomial time mixing of Gibbs sampler in a situation where the actual mixing time is slower than npolylog(n). Our proof exploits in novel ways the local tree like structure of Erd,s-Rényi random graphs, comparison and block dynamics arguments and a recent result of Weitz. Our results extend to much more general families of graphs which are sparse in some average sense and to much more general interactions. In particular, they apply to any graph for which every vertex v of the graph has a neighborhood N(v) of radius O(log n) in which the induced sub-graph is a tree union at most O(log n) edges and where for each simple path in N(v) the sum of the vertex degrees along the path is O(log n). Moreover, our result apply also in the case of arbitrary external fields and provide the first FPRAS for sampling the Ising distribution in this case. We finally present a non Markov Chain algorithm for sampling the distribution which is effective for a wider range of parameters. In particular, for G(n, d/n) it applies for all external fields and , < ,d, where d tanh(,d) = 1 is the critical point for decay of correlation for the Ising model on G(n, d/n). © 2009 Wiley Periodicals, Inc. Random Struct. Alg., 2009 [source] The evolution of the mixing rate of a simple random walk on the giant component of a random graphRANDOM STRUCTURES AND ALGORITHMS, Issue 1 2008N. Fountoulakis Abstract In this article we present a study of the mixing time of a random walk on the largest component of a supercritical random graph, also known as the giant component. We identify local obstructions that slow down the random walk, when the average degree d is at most O(), proving that the mixing time in this case is ,((n/d)2) asymptotically almost surely. As the average degree grows these become negligible and it is the diameter of the largest component that takes over, yielding mixing time ,(n/d) a.a.s.. We proved these results during the 2003,04 academic year. Similar results but for constant d were later proved independently by Benjamini et al. in 3. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008 [source] Approximating average parameters of graphs,,RANDOM STRUCTURES AND ALGORITHMS, Issue 4 2008Oded Goldreich Abstract Inspired by Feige (36th STOC, 2004), we initiate a study of sublinear randomized algorithms for approximating average parameters of a graph. Specifically, we consider the average degree of a graph and the average distance between pairs of vertices in a graph. Since our focus is on sublinear algorithms, these algorithms access the input graph via queries to an adequate oracle. We consider two types of queries. The first type is standard neighborhood queries (i.e., what is the ith neighbor of vertex v?), whereas the second type are queries regarding the quantities that we need to find the average of (i.e., what is the degree of vertex v? and what is the distance between u and v?, respectively). Loosely speaking, our results indicate a difference between the two problems: For approximating the average degree, the standard neighbor queries suffice and in fact are preferable to degree queries. In contrast, for approximating average distances, the standard neighbor queries are of little help whereas distance queries are crucial. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008 [source] Separation and quantification of inulin in selected artichoke (Cynara scolymus L.) cultivars and dandelion (Taraxacum officinale WEB. ex WIGG.) roots by high-performance anion exchange chromatography with pulsed amperometric detectionBIOMEDICAL CHROMATOGRAPHY, Issue 12 2006Katrin Schütz Abstract The profile of fructooligosaccharides and fructopolysaccharides in artichoke heads and dandelion roots was investigated. For this purpose, a suitable method for high-performance anion exchange chromatography with pulsed amperometic detection was developed. The separation of monomers, oligomers and polymers up to a chain length of 79 sugar residues was achieved in one single run. Glucose, fructose, sucrose and individual fructooligosaccharides (kestose, nystose, fructofuranosylnystose) were quantified in six different artichoke cultivars and in dandelion roots. The contents ranged from 12.9 g/kg DM to 71.7 g/kg DM for glucose, from 15.8 g/kg DM to 67.2 g/kg DM for fructose, and from 16.8 g/kg DM to 55.2 g/kg DM for sucrose in the artichoke heads. Kestose was the predominant fructooligosaccharide, followed by nystose and fructofuranosylnystose. In four cultivars fructofuranosylnystose was only detectable in traces and reached its maximum value of 3.6 g/kg DM in the cultivar Le Castel. Furthermore, an average degree of polymerization of 5.3 to 16.7 was calculated for the individual artichoke cultivars, which is noticeably lower than hitherto reported. In contrast, the contents of kestose, nystose and fructofuranosylnystose in dandelion root exceeded that of artichoke, reflecting the short chain characteristic of the inulin, which was confirmed by chromatographic analysis. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||||||||