4,368 research outputs found
Magnetised Polish doughnuts revisited
We discuss a procedure to build new sequences of magnetised, equilibrium tori
around Kerr black holes which combines two approaches previously considered in
the literature. For simplicity we assume that the test-fluid approximation
holds, and hence we neglect the self-gravity of the fluid. The models are built
assuming a particular form of the angular momentum distribution from which the
location and morphology of equipotential surfaces can be computed. This ansatz
includes, in particular, the constant angular momentum case originally employed
in the construction of thick tori - or Polish doughnuts - and it has already
been used to build equilibrium sequences of purely hydrodynamical models. We
discuss the properties of the new models and their dependence on the initial
parameters. These new sequences can be used as initial data for
magnetohydrodynamical evolutions in general relativity.Comment: 9 pages, 6 figures. Accepted for publication in Astronomy &
Astrophysics July 12, 201
Self-gravitating magnetised tori around black holes in general relativity
We investigate stationary, self-gravitating, magnetised disks (or tori)
around black holes. The models are obtained by numerically solving the coupled
system of the Einstein equations and the equations of ideal
general-relativistic magnetohydrodynamics. The mathematical formulation and
numerical aspects of our approach are similar to those reported in previous
works modeling stationary self-gravitating perfect-fluid tori, but the
inclusion of magnetic fields represents a new ingredient. Following previous
studies of purely hydrodynamical configurations, we construct our models
assuming Keplerian rotation in the disks and both spinning and spinless black
holes. We focus on the case of a toroidal distribution of the magnetic field
and build a large set of models corresponding to a wide range of values of the
magnetisation parameter, starting with weakly magnetised disks and ending at
configurations in which the magnetic pressure dominates over the thermal one.
In all our models, the magnetic field affects the equilibrium structure of the
torus mainly due to the magnetic pressure. In particular, an increasing
contribution of the magnetic field shifts the location of the maximum of the
rest-mass density towards inner regions of the disk. The total mass of the
system and the angular momentum are affected by the magnetic field in a complex
way, that depends on the black hole spin and the location of the inner radius
of the disk. The non-linear dynamical stability of the solutions presented in
this paper will be reported elsewhere.Comment: 17 pages, 5 figures, 1 tabl
Lujo y primera necesidad: definición y evolución en España
La elemental referencia a la elasticidad renta de los
diversos bienes y servicios, tradicional criterio para
definir los viejos conceptos de bienes de lujo e inferiores
(no propiamente los de primera necesidad), resulta insuficiente cuando la relación entre consumo y renta no mantiene
una relación tan clara como exigiría dicho criterio .
Se comprueba que la función y = (ax^b)*(e^cx) (donde x es el
nivel de renta e y la proporción de la misma destinada a
cada bien o servicio) permite una estimación altamente
significativa de la evolución del consumo en función de la
renta.
El signo de los índices b y c de la función antedicha
permite una primera aproximación convencional al carácter
de los distintos bienes. Se sugiere el valor del coeficiente a como índice adecuado del grado de necesidad. Cuando la
relación no es unívoca, el punto de inflexión resulta una
información de gran importancia.
La estimación de las funciones para los hogares
españoles en los años 1973, 1980 y 1990 permite extraerlas
correspondientes consecuencias y comparar la evolución de
los conceptos analizados a lo largo de tan amplio y
significativo período de tiempo. Se dedica una especial
atención a las llamadas necesidades preferentes, educación,
sanidad y, sobre todas, vivienda por el atípico perfil que
presenta
'Globesization': ecological evidence on the relationship between fast food outlets and obesity among 26 advanced economies
The aim of this study was to investigate the relationship between the density of fast food restaurants and the prevalence of obesity by gender across affluent nations. Data on Subway’s restaurants per 100,000 people and proportions of men and women aged 15 years or older with a body mass index (BMI) higher or equal than 30 Kg/m2 were obtained for 26 of 34 advanced economies. Countries with the highest density of Subway restaurants such as the US (7.52 per 100,000) and Canada (7.43 per 100,000) tend also to have a higher prevalence of obesity in both men (31.3% and 23.2% respectively) and women (33.2% and 22.9% respectively). On the other hand, countries with a relatively low density of Subway restaurants such as Japan (0.13 per 100,000) and Norway (0.19 per 100,000) had a lower prevalence of obesity in both men (2.9% and 6.4% respectively) and women (3.3% and 5.9% respectively). Unadjusted linear regression models showed a significant correlation between the density of Subway’s outlets and the prevalence of adult obesity (β=.46; p=0.02 in men and β=.48; p=0.013 in women). When the data were weighted by population size, the association became substantially stronger in both men and women (β=.85; p=0.0001 and β=.84; p=0.0001, respectively). Covariate adjustment did not reduce the size of the associations. Our study raises serious concerns about that the diffusion of fast food outlets worldwide and calls for coordinated political actions to address what we term ‘globesization’, the ongoing globalization of the obesity epidemic
Crop year, harvest date and clone effects on fruit characteristics, chemical composition and olive oil stability from an Empeltre clonal selection grown in Aragon
BACKGROUND In this study, the effects of crop year, harvest date and clone on the fruit characteristics and chemical composition of Empeltre olive oils were evaluated. For this purpose, the weight and oil content of fruit and the fatty acid composition, polyphenol content and oxidative stability of the olive oil was analysed throughout ripening during three successive seasons. RESULTS The weight and moisture in the fruit, as well as the fatty acids and polyphenol content in the olive oil, were mainly affected by crop year. In contrast, the stability was strongly influenced by the harvest date. Both factors had an influence on the fruit''s oil content. The clone was not a substantial component in terms of variability, although the interaction with crop year was notable for some of the characteristics. The oil content increased significantly along with the harvest date and reached maximum values in the last period (44.9%). Conversely, stability and polyphenols decreased significantly (depending on the year, by 30-70%) from October to December, reaching the highest mean values between 1 October and 10 November (15.5 h; 500 mg caffeic acid kg(-1)). Oleic acid and monounsaturated/polyunsaturated fatty acids (MUFA/PUFA) did not show significant differences depending on the harvest date, but between years, with 2018 having the highest percentage of oleic acid (72.72%) and MUFA/PUFA (8.38). CONCLUSION Early harvesting of Empeltre olives would provide considerably more stable olive oils, regardless of the clone selected, with higher phenolic content. It would not affect the MUFA/PUFA ratio, mainly influenced by the crop year. (c) 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry
Thermally activated delayed fluorescence in neutral and cationic copper(I) complexes with the 2-(4-Thiazolyl)benzimidazole ligand
Cationic [Cu(P^P)(Htbz)]PF6 [P^P = xantphos, dpephos; Htbz = 2-(4-thiazolyl)benzimidazole] and the corresponding neutral complexes [Cu(P^P)(tbz)], obtained through deprotonation of the diimine ligand, have been synthesized with the aim of analyzing the role of the diphosphane and Htbz deprotonation in the emissive properties of these complexes. For the study of the diphosphane effect, the luminescence properties of these compounds have been compared with those of the reported analogous derivatives with Htbz and carborane diphosphanes. Complexes [Cu(P^P)(Htbz)]PF6 (P^P = xantphos, dpephos) and [Cu(dpephos)(tbz)] display thermally activated delayed fluorescence, which has been studied, revealing a ΔE(S1–T1) between 658 and 455 cm–1. Theoretical calculations indicate different origins for the absorptions, leading to the observed emissions
Asymptotically Extrinsic Tamed Submanifolds
We study, from the extrinsic point of view, the structure at infinity of open
submanifolds, ϕ : Mm → Mn(κ) isometrically immersed in the real space forms of
constant sectional curvature κ ≤ 0.We shall use the decay of the second fundamental
form of the so-called tamed immersions to obtain a description at infinity of the
submanifold in the line of the structural results in Greene et al. (Int Math Res Not
1994:364–377, 1994) and Petrunin and Tuschmann (Math Ann 321:775–788, 2001)
and an estimation from below of the number of its ends in terms of the volume growth
of a special class of extrinsic domains, the extrinsic balls.Vicent Gimeno: Work partially supported by the Research Program of University Jaume I Project UJI-B2016-07, and DGI -MINECO Grant (FEDER) MTM2013-48371-C2-2-P. Vicente Palmer: Work partially supported by the Research Program of University Jaume I Project UJI-B2016-07, DGI -MINECO Grant (FEDER) MTM2013-48371-C2-2-P, and Generalitat Valenciana Grant PrometeoII/2014/064. G. Pacelli Bessa: Work partially supported by CNPq- Brazil grant # 301581/2013-4
Genomic variation and population structure detected by single nucleotide polymorphism arrays in Corriedale, Merino and Creole sheep.
THE AIM OF THIS STUDY WAS TO INVESTIGATE THE GENETIC DIVERSITY WITHIN AND AMONG THREE BREEDS OF SHEEP: Corriedale, Merino and Creole. Sheep from the three breeds (Merino n = 110, Corriedale n = 108 and Creole n = 10) were genotyped using the Illumina Ovine SNP50 beadchip(®). Genetic diversity was evaluated by comparing the minor allele frequency (MAF) among breeds. Population structure and genetic differentiation were assessed using STRUCTURE software, principal component analysis (PCA) and fixation index (FST). Fixed markers (MAF = 0) that were different among breeds were identified as specific breed markers. Using a subset of 18,181 single nucleotide polymorphisms (SNPs), PCA and STUCTURE analysis were able to explain population stratification within breeds. Merino and Corriedale divergent lines showed high levels of polymorphism (89.4% and 86% of polymorphic SNPs, respectively) and moderate genetic differentiation (FST = 0.08) between them. In contrast, Creole had only 69% polymorphic SNPs and showed greater genetic differentiation from the other two breeds (FST = 0.17 for both breeds). Hence, a subset of molecular markers present in the OvineSNP50 is informative enough for breed assignment and population structure analysis of commercial and Creole breeds
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