670 research outputs found
The Bardeen–Petterson effect in accreting supermassive black hole binaries: a systematic approach
No full textDisc-driven migration is a key evolutionary stage of supermassive black-hole binaries hosted in gas-rich galaxies. Besides promoting the inspiral, viscous interactions tend to align the spins of the black holes with the orbital angular momentum of the disc. We present a critical and systematic investigation of this problem, also known as the Bardeen-Petterson effect. We design a new iterative scheme to solve the non-linear dynamics of warped accretion discs under the influence of both relativistic frame dragging and binary companion. We characterize the impact of the disc "critical obliquity", which marks regions of the parameter space where stationary solutions do not exist. We find that black-hole spins reach either complete alignment or a critical configuration. Reaching the critical obliquity might imply that the disc breaks as observed in hydrodynamical simulations. Our findings are important to predict the spin configurations with which supermassive black-hole binaries enter their gravitational-wave driven regime and become detectable by LISA
The Bardeen-Petterson effect as the precession mechanism for the radio galaxy 3C 84 (NGC 1275)
No full textAbstractIn this work we propose the Bardeen-Petterson effect as the precession mechanism of the jet precession in NGC 1275. To check if this is true we have estimated the angular momentum ratio and the aligment timescale predict by the theory and compared with the numerical results presented in the literature. We were able to explain the precession period assuming an accretion disk with column surface density in the form of a power law with exponent 0.6 < s < 0.7 and a black hole rotation with a spin of 0.23 < a∗<0.4.</jats:p
sj-pdf-1-vmj-10.1177_1358863X241238702 – Supplemental material for Sitting knee-flexion angle does not influence endothelial-dependent vasodilation in laboratory or free-living conditions
No full textSupplemental material, sj-pdf-1-vmj-10.1177_1358863X241238702 for Sitting knee-flexion angle does not influence endothelial-dependent vasodilation in laboratory or free-living conditions by Madeline E Shivgulam, Myles W O’Brien, Yanlin Wu, Haoxuan Liu, Jennifer L Petterson, Beverly D Schwartz and Derek S Kimmerly in Vascular Medicine</p
Hash kernels
No full textWe propose hashing to facilitate efficient kernels. This generalizes previous work using sampling and we show a principled way to compute the kernel matrix for data streams and sparse feature spaces. Moreover, we give deviation bounds from the exact kernel matrix. This has applications to estimation on strings and graphs.Qinfeng Shi, James Petterson, Gideon Dror, John Langford, Alex Smola, Alex Strehl and Vishy Vishwanatha
Análise da seletividade na cloração de butanona para obtenção de acetoína
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Curso de Pós-Graduação em Físico-Químic
André Petterson : 1974-86
No full textAs a prelude to McDonald's analysis of Peterson's multimedia works (1976-1986), the author outlines the Dutch-born artist's musical endeavors and identifies isolation and alienation as the oeuvre's connecting themes. Biographical notes. 23 bibl. ref
A novel natural tracer method to measure complex carbohydrate metabolism
No full textWhile the triple tracer isotope dilution method has enabled accurate estimation of carbohydrate turnover after a mixed meal, use of the simple carbohydrate glucose as the carbohydrate source limits its translational applicability to everyday meals that typically contain complex carbohydrates. Hence, utilizing the natural enrichment of [13C]polysaccharide in commercially available grains, we devised a novel tracer method to measure postprandial complex carbohydrate turnover and indices of insulin action and β-cell function and compared the parameters to those obtained after a simple carbohydrate containing mixed meal. We studied healthy volunteers after either rice (n = 8) or sorghum (n = 8) and glucose (n = 16) containing mixed meals and modified the triple tracer technique to calculate carbohydrate turnover. All meals were matched for calories and macronutrient composition. Rates of meal glucose appearance (2,658 ± 736 vs. 4,487 ± 909 μM·kg-1·2 h-1), endogenous glucose production (-835 ± 283 vs. -1,123 ± 323 μM·kg-1·2 h-1) and glucose disappearance (1,829 ± 807 vs. 3,606 ± 839 μM·kg-1·2 h-1) differed (P < 0.01) between complex and simple carbohydrate containing meals, respectively. Interestingly, there were significant increase in indices of insulin sensitivity (32.5 ± 3.5 vs. 25.6 ± 3.2 10-5 (dl·kg-1·min-2)/pM, P = 0.006) and β-cell responsivity (disposition index: 1,817 ± 234 vs. 1,236 ± 159 10-14 (dl·kg-1·min-2)/pM, P < 0.005) with complex than simple carbohydrate meals. We present a novel triple tracer approach to estimate postprandial turnover of complex carbohydrate containing mixed meals. We also report higher insulin sensitivity and β-cell responsivity with complex than with simple carbohydrates in mixed meals of identical calorie and macronutrient compositions in healthy adults
Modelling height-diameter relationships of Pinus radiata plantations in Canterbury, New Zealand
No full textThis paper describes the modelling of height-diameter relationships for Pinus radiata D. Don at stand and individual tree levels in Canterbury, New Zealand. Sixteen functional forms were evaluated for stands that varied considerably in stand age, site index, altitude and the number of trees sampled. The Petterson equation with exponent -5 and the two-parameter Richards’ equation both gave the smallest average mean square error. The inclusion of stand age, site index and altitude into the Petterson equation reduced mean square error by 72% in the regional height-diameter model
Modelling height-diameter relationships of Pinus radiata plantations in Canterbury, New Zealand
No full textThis paper describes the modelling of height-diameter relationships for Pinus radiata D. Don at stand and individual tree levels in Canterbury, New Zealand. Sixteen functional forms were evaluated for stands that varied considerably in stand age, site index, altitude and the number of trees sampled. The Petterson equation with exponent -5 and the two-parameter Richards’ equation both gave the smallest average mean square error. The inclusion of stand age, site index and altitude into the Petterson equation reduced mean square error by 72% in the regional height-diameter model
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