53,718 research outputs found
Nature Red Tooth and Claw: Studies of Extinct and Extant Arthropod Predator-Prey Systems
No full textThe majority of the data that are included are in the form of photographs of specimens formatted into figures. The organisms that are figured include ants (Barlow et al., 2019), horseshoe crabs - both live and fossil (Bicknell et al., 2018d; Bicknell et al., 2018e; Bicknell and Pates, in press) - , Cambrian aged trilobites (Pates et al., 2017; Bicknell and Paterson, 2018; Pates and Bicknell, 2019) and other other Cambrian aged arthropods and fossils (Bicknell et al., 2018c; Bicknell and Paterson, 2018). Two examples of Ediacaran organisms are also figured (Paterson et al., 2017; Bicknell and Paterson, 2018). These data allow for specimens to be depicted and discussed.
Other data include figures that are made from CT and micro-CT data of horseshoe crabs (Bicknell et al., 2018b; Bicknell et al., 2018c). Related to these data are the raw micro-CT scans and CT scans (Bicknell et al., 2018b; Bicknell et al., 2018c) and the results of the biomechanical analyses (Bicknell et al., 2018c).
Finally, morphometric (shape) data are included and were used to explore shape change, evolution, and population dynamics (Paterson et al., 2017; Pates et al., 2017; Bicknell et al., 2018a)
Binding of D-phenylalanine and D-tyrosine To Carboxypeptidase-a
No full textThe structures of the complexes of carboxypeptidase A with the amino acids D-phenylalanine and D-tyrosine are reported as determined by x-ray crystallographic methods to a resolution of 2.0 A. In each individual study one molecule of amino acids binds to the enzyme in the COOH-terminal hydrophobic pocket: the carboxylate of the bound ligand salt links with Arg-145, and the alpha-amino group salt links with Glu-270. The carboxylate of Glu-270 must break its hydrogen bond with the native zinc-bound water molecule in order to exploit the latter interaction. This result is in accord with spectroscopic studies which indicate that the binding of D or L amino acids (or analogues thereof) allows for more facile displacement of the metal-bound water by anions (Bicknell, R., Schaffer, A., Bertini, I., Luchinat, C., Vallee, B. L., and Auld, D. S. (1988) Biochemistry 27, 1050-1057). Additionally, we observe a significant movement of the zinc-bound water molecule (approximately 1 A) upon the binding of D-ligands. We propose that this unanticipated movement also contributes to anion sensitivity. The structural results of the current x-ray study correct predictions made in an early model building study regarding the binding of D-phenylalanine (Lipscomb, W. N., Hartsuck, J. A., Reeke, G. N., Jr., Quiocho, F. A., Bethge, P. H., Ludwig, M. L., Steitz, T. A., Muirhead, H., and Coppola, J. C. (1968) Brookhaven Symp. Biol. 21, 24-90)
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Letter from C. D. Dawson, Tusayan Copper Mining and Smelting, to Carl Hayden
No full textLetter from C. D. Dawson to Carl Hayden urging him to consider the rights of miners and farmers when drawing up the boundaries for the proposed park
Supporting the development of number fact knowledge in five- and six-year-olds
No full textThis paper focuses on children’s number fact knowledge from a study that explored the impact of using multiplication and division contexts for developing number understanding with 34 five- and six-year-old children from diverse cultural and linguistic backgrounds. After a series of focused lessons, children’s knowledge of number facts, including single digit addition, subtraction, and doubles had improved. However, they did not always apply this knowledge to relevant problem-solving situations. The magnitude of the numbers did not necessarily determine the difficulty level for achieving automaticity of number fact knowledge
Polyploid and aneuploid detection in apple using a single nucleotide polymorphism array
No full textPolyploidisation is a common mechanism underlying genome evolution in plants. Both polyploid and aneuploid individuals occur naturally at low frequency in diploid species because of unbalanced or unreduced gamete formation during meiosis. We evaluated the Illumina Infinium® II FruitBreedomics 20K apple single nucleotide polymorphism (SNP) array for its ability to detect polyploid and aneuploid individuals in an apple germplasm collection comprising 663 genotypes. The set of SNPs employed to perform the analysis consisted of 6733 high-quality polymorphic markers spanning the entire apple genome at an average density of one SNP every 85.6 kb. The method we used to detect chromosomal aberrations is based on analysis of the B allele frequency (BAF) at each SNP position. We have demonstrated that this simple method can be used successfully to detect triploid, tetraploid and aneuploid accessions of apple and validated our findings using flow cytometry analysi
Developing young children's understanding of place-value using multiplication and quotitive division
No full textThis paper focuses on selected findings from a study that explored the use of multiplication and division with 34 five- and six-year-old children from diverse cultural and linguistic backgrounds. The focus of instructional tasks was on working with groups of ten to support the understanding of place value. Findings from relevant assessment tasks and children’s work highlighted the importance of encouraging young children to move from unitary (counting by ones) to tens-structured thinking
Measurement of the D+/- production asymmetry in 7 TeV pp collisions
No full textThe asymmetry in the production cross-section \sigma of D+/- mesons, A_P = (\sigma(D+) - \sigma(D-))/(\sigma(D+) + \sigma(D-)), is measured in bins of pseudorapidity \eta and transverse momentum p_T within the acceptance of the LHCb detector. The result is obtained with a sample of D+ -> K_S pi+ decays corresponding to an integrated luminosity of 1.0 fb^-1, collected in pp collisions at a centre of mass energy of 7 TeV at the Large Hadron Collider. When integrated over the kinematic range 2.0 K_S pi+ decay is negligible. No significant dependence on \eta or p_T is observed
D* (D)over-bar* molecule interpretation of Z(c)(4025)
No full textWe have used QCD sum rules to study the newly observed charged state Z(c)(4025) as a hidden-charm D*(D) over bar* molecular state with the quantum numbers I-G(J(P)) =1(+)(1(+)). Using a D*(D) over bar* molecular interpolating current, we have calculated the two-point correlation function and the spectral density up to dimension eight at leading order in alpha(s). The extracted mass is m(X) = (4.04 +/- 0.24) GeV. This result is compatible with the observed mass of Z(c)(4025) within the errors, which implies a possible molecule interpretation of this new resonance. We also predict the mass of the corresponding hidden-bottom B*(B) over bar* molecular state: m(Zb) = (9.98 +/- 0.21) GeV.Physics, Particles & FieldsSCI(E)[email protected]; [email protected]; [email protected]; [email protected]
Prompt charm production in pp collisions at √<span style="text-decoration:overline">s</span>=7 TeV
No full textCharm production at the LHC in pp collisions at s√=7 TeV is studied with the LHCb detector. The decays D0→K−π+, D+→K−π+π+, D⁎+→D0(K−π+)π+, D+s→ϕ(K−K+)π+, Λ+c→pK−π+, and their charge conjugates are analysed in a data set corresponding to an integrated luminosity of 15 nb−1. Differential cross-sections dσ/dpT are measured for prompt production of the five charmed hadron species in bins of transverse momentum and rapidity in the region 0<pT<8 GeV/c and 2.0<y<4.5. Theoretical predictions are compared to the measured differential cross-sections. The integrated cross-sections of the charm hadrons are computed in the above pT-y range, and their ratios are reported. A combination of the five integrated cross-section measurements gives
σ(cc¯)pT<8 GeV/c,2.0<y<4.5=1419±12(stat)±116(syst)±65(frag) μb,
where the uncertainties are statistical, systematic, and due to the fragmentation functions
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