Toward stable 3D numerical evolutions of black-hole spacetimes

Three dimensional (3D) numerical evolutions of static black holes with excision are presented. These evolutions extend to about 8000M, where M is the mass of the black hole. This degree of stability is achieved by using growth-rate estimates to guide the fine tuning of the parameters in a multi-parameter family of symmetric hyperbolic representations of the Einstein evolution equations. These evolutions were performed using a fixed gauge in order to separate the intrinsic stability of the evolution equations from the effects of stability-enhancing gauge choices.Comment: 4 pages, 5 figures. To appear in Phys. Rev. D. Minor additions to text for clarification. Added short paragraph about inner boundary dependenc

Impact of densitized lapse slicings on evolutions of a wobbling black hole

We present long-term stable and second-order convergent evolutions of an excised wobbling black hole. Our results clearly demonstrate that the use of a densitized lapse function extends the lifetime of simulations dramatically. We also show the improvement in the stability of single static black holes when an algebraic densitized lapse condition is applied. In addition, we introduce a computationally inexpensive approach for tracking the location of the singularity suitable for mildly distorted black holes. The method is based on investigating the fall-off behavior and asymmetry of appropriate grid variables. This simple tracking method allows one to adjust the location of the excision region to follow the coordinate motion of the singularity.Comment: 10 pages, 8 figure

Energy Norms and the Stability of the Einstein Evolution Equations

The Einstein evolution equations may be written in a variety of equivalent analytical forms, but numerical solutions of these different formulations display a wide range of growth rates for constraint violations. For symmetric hyperbolic formulations of the equations, an exact expression for the growth rate is derived using an energy norm. This expression agrees with the growth rate determined by numerical solution of the equations. An approximate method for estimating the growth rate is also derived. This estimate can be evaluated algebraically from the initial data, and is shown to exhibit qualitatively the same dependence as the numerically-determined rate on the parameters that specify the formulation of the equations. This simple rate estimate therefore provides a useful tool for finding the most well-behaved forms of the evolution equations.Comment: Corrected typos; to appear in Physical Review

Improved numerical stability of stationary black hole evolution calculations

We experiment with modifications of the BSSN form of the Einstein field equations (a reformulation of the ADM equations) and demonstrate how these modifications affect the stability of numerical black hole evolution calculations. We use excision to evolve both non-rotating and rotating Kerr-Schild black holes in octant and equatorial symmetry, and without any symmetry assumptions, and obtain accurate and stable simulations for specific angular momenta J/M of up to about 0.9M.Comment: 13 pages, 11 figures, 1 typo in Eq. (20) correcte

Substance P and Calcitonin gene-related peptide expression in human periodontal ligament after root canal preparation with Reciproc Blue, WaveOne Gold, XP EndoShaper and hand files

Aim: To quantify Substance P (SP) and Calcitonin gene-related peptide (CGRP) expression in healthy human periodontal ligament from premolars after root canal preparation with Reciproc Blue, WaveOne Gold, XP EndoShaper and hand files. Methodology: A total of 50 human periodontal ligament samples were obtained from healthy mandibular premolars where extraction was indicated for orthodontic reasons. Prior to extraction, 40 of these premolars were equally divided into four groups, and root canals were prepared using four different systems: Reciproc Blue, WaveOne Gold, XP EndoShaper and a hand instrumentation technique. The remaining 10 healthy premolars were extracted without treatment and served as a negative control group. All periodontal ligament samples were processed, and SP and CGRP were measured by radioimmunoassay. The Kruskal–Wallis test was used to establish significant differences between groups and LSD post hoc comparisons were also performed. Results: Greater SP and CGRP values were found in the hand instrumentation group, followed by the XP EndoShaper, WaveOne Gold and the Reciproc groups. The lower SP and CGRP values were for the healthy periodontal ligament group. The Kruskal–Wallis test revealed significant differences between groups (P  less than  0.05). Post hoc Least Significant Difference (LSD) tests revealed significant differences (P  less than  0.05) in SP and CGRP expression between all the comparisons except for the Reciproc Blue and WaveOne Gold group (P > 0.05). Conclusion: All the root canal preparation techniques tested increased SP and CGRP expression in human periodontal ligament, with hand files and XP EndoShaper instruments being associated with greater neuropeptide release compared to Reciproc Blue and WaveOne Gold files. © 2018 International Endodontic Journal. Published by John Wiley and Sons Lt

Substance P and Calcitonin gene-related peptide expression in human periodontal ligament after root canal preparation with Reciproc Blue, WaveOne Gold, XP EndoShaper and hand files

Aim: To quantify Substance P (SP) and Calcitonin gene-related peptide (CGRP) expression in healthy human periodontal ligament from premolars after root canal preparation with Reciproc Blue, WaveOne Gold, XP EndoShaper and hand files. Methodology: A total of 50 human periodontal ligament samples were obtained from healthy mandibular premolars where extraction was indicated for orthodontic reasons. Prior to extraction, 40 of these premolars were equally divided into four groups, and root canals were prepared using four different systems: Reciproc Blue, WaveOne Gold, XP EndoShaper and a hand instrumentation technique. The remaining 10 healthy premolars were extracted without treatment and served as a negative control group. All periodontal ligament samples were processed, and SP and CGRP were measured by radioimmunoassay. The Kruskal–Wallis test was used to establish significant differences between groups and LSD post hoc comparisons were also performed. Results: Greater SP and CGRP values were found in the hand instrumentation group, followed by the XP EndoShaper, WaveOne Gold and the Reciproc groups. The lower SP and CGRP values were for the healthy periodontal ligament group. The Kruskal–Wallis test revealed significant differences between groups (P  less than  0.05). Post hoc Least Significant Difference (LSD) tests revealed significant differences (P  less than  0.05) in SP and CGRP expression between all the comparisons except for the Reciproc Blue and WaveOne Gold group (P > 0.05). Conclusion: All the root canal preparation techniques tested increased SP and CGRP expression in human periodontal ligament, with hand files and XP EndoShaper instruments being associated with greater neuropeptide release compared to Reciproc Blue and WaveOne Gold files. © 2018 International Endodontic Journal. Published by John Wiley and Sons Lt

Efeito do genótipo sobre a produção e a composição do leite de cabras mestiças Effect of genotype on milk yield and composition of crossbred goats

O potencial de produção de trinta e cinco cabras mestiças - 12 &frac12;Pardo-alpina + &frac12;Moxotó (&frac12;PA-M), 11&frac34; Pardo-alpina + &frac14;Moxotó (&frac34;PA-M) e 12 Tricross (&frac12;Anglo-nubiana + &frac14;Pardo-alpina + &frac14;Moxotó) - foi avaliado em um experimento foi conduzido na Embrapa Caprinos. Os cabritos foram separados das respectivas mães ao nascimento. As cabras foram ordenhadas duas vezes ao dia e o controle leiteiro procedido semanalmente. Os animais foram confinados em baias coletivas e receberam dieta para produção de 2,5 kg de leite/dia, composta de silagem de sorgo ad libitum e concentrado. Os animais foram pesados em intervalos de 14 dias. A produção de leite, como coletada, não foi influenciada pelo genótipo. No entanto, quando foi corrigida para 4% de gordura, o genótipo &frac12; PA-M foi superior aos &frac34; PA-M e Tricross. Não houve diferença significativa entre genótipos para gordura, proteína e extrato seco total do leite.<br>The objective of this trial was to study the production of thirty-five crossbred goats: ½Brown Alpine x 12 ½Moxoto (½BA-M), 11 ¾Brown Alpine x ¼Moxoto (¾BA-M), and 12 Tricross (½Anglo Nubian x ¼Moxoto x ¼Brown Alpine). After birth, the kids were separated from their mothers. Goats were milked twice a day and milk composition determined weekly. Animals were housed in collective pens and received a diet composed of sorghum silage (ad libitum) plus concentrate that were formulated to allow 2.5 kg/d of milk yield. Animals were weighted every 14 days. Milk production did not differ among genotypes. However, 4% fat corrected milk was greater for ½BA-M than the remaining groups. No significant differences were observed for milk composition (fat, protein, and total solids) across genotypes in the current trial

Symmetric hyperbolicity and consistent boundary conditions for second-order Einstein equations

We present two families of first-order in time and second-order in space formulations of the Einstein equations (variants of the Arnowitt-Deser-Misner formulation) that admit a complete set of characteristic variables and a conserved energy that can be expressed in terms of the characteristic variables. The associated constraint system is also symmetric hyperbolic in this sense, and all characteristic speeds are physical. We propose a family of constraint-preserving boundary conditions that is applicable if the boundary is smooth with tangential shift. We conjecture that the resulting initial-boundary value problem is well-posed

Método eletroforético rápido para detecção da adulteração do leite caprino com leite bovino Fast electrophoretic detection method of adulteration of caprine milk by bovine milk

Avaliaram-se os métodos de eletroforese em gel de poliacrilamida (PAGE) em presença de uréia (uréia-PAGE) e dodecil sulfato de sódio (SDS-PAGE) para identificar a adulteração do leite de cabra pela adição do leite de vaca. Um método foi otimizado para preparação do caseinato de sódio em poucos minutos para análise eletroforética. Uréia-PAGE foi o método mais apropriado para identificação desse tipo de fraude, em decorrência da presença da caseína alfas1 com migração mais rápida no leite bovino. A presença da alfas1-caseína bovina foi detectada a partir da adição de 2,5% de leite de vaca utilizando uréia-PAGE. O limite de detecção, a repetibilidade, o tempo para execução indicaram que esse método pode ser aplicado como rotina no controle de qualidade do leite de cabra recebido pelas indústrias de processamento.<br>Polyacrylamide gel electrophoresis (PAGE) in presence of urea (urea-PAGE) or sodium dodecyl sulfate (SDS-PAGE) was evaluated to detect the presence of cow milk added to goat milk. A method was optimized to prepare sodium caseinate from milk in few minutes. After that, the sodium caseinate was analyzed by PAGE. The urea-PAGE was the most appropriated method to identify adulteration as caprine and bovine alphas1-caseins displayed different migration rates. When cow milk was added to goat milk at different proportions, the presence of bovine alphas1-casein was detected in the mixture by urea-PAGE for a minimal proportion of 2.5% of cow milk added to goat milk. The good sensitivity, the repeatability and the short time for execution indicate that the described method will be able to be routinely applied for the quality control of goat milk in dairy industry