There exist well-known no-hair theorems forbidding the existence of hairy black hole solutions in general relativity coupled to a scalar conformal field theory in asymptotically flat space. Even in the presence of cosmological constant, where no-hair theorems can usually be circumvented and black holes with conformal scalar hair were shown to exist in D ≤ 4 dimensions, no-go results were reported for D > 4. In this paper we prove that these obstructions can be evaded and we answer in the affirmative a question that remained open: Whether hairy black holes do exist in general relativity sourced by a conformally coupled scalar field in arbitrary dimensions. We find the analytic black hole solution in arbitrary dimension D > 4, which exhibits a backreacting scalar hair that is regular everywhere outside and on the horizon. The metric asymptotes to (Anti-)de Sitter spacetime at large distance and admits spherical horizon as well as horizon of a different topology. We also find analytic solutions when higher-curvature corrections O(R n ) of arbitrary order n are included in the gravity action.
In children, inappropriate eating habits can induce a disease known as nutritional dwarfing (ND). Due to the link between nutritional condition and bone growth, the effects induced by a 20 % reduction of food intake on bone competence were assessed in an animal model of ND. Bone status during catch-up growth was also analysed. Male Wistar rats were divided into control (C) and ND groups. C rats were fed ad libitum. ND received 80 % of the diet consumed by C for 4 weeks (T4); thereafter, they were fed ad libitum for 8 weeks. Results, expressed as mean (SEM) for ND v. C, were as follows. At T4, body weight (g) and length (cm) and femur weight (g) and length (mm) were 97.35 (SEM 5.89) v. 199.07 (SEM 9.24), 16.91 (SEM 0.41) v. 20.26 (SEM 0.31), 0.30 (SEM 0.01) v. 0.46 (SEM 0.01) and 23.09 (SEM 0.29) v. 26.98 (SEM 0.26), respectively (P<0.001); bone mineral content (g) and density (g/cm(2)) were 0.014 (SEM 0.002) v. 0.030 (SEM 0.002) and 0.061 (SEM 0.004) v. 0.080 (SEM 0.003), respectively (P<0.001); load-bearing capacity (N), yielding load (N) and elastic stiffness (N/mm) were 25.06 (SEM 1.24) v. 50.34 (SEM 2.94), 23.72 (SEM 1.02) v. 46.97 (SEM 1.75) and 65.98 (SEM 4.42) v. 115.07 (SEM 3.85), respectively (P<0.001); cross-sectional area (mm(2)) and moment of inertia (mm(4)) were 2.86 (SEM 0.19) v. 4.54 (SEM 0.17) and 1.27 (SEM 0.08) v. 3.03 (SEM 0.16), respectively (P<0.001). Significant effects were not evident in material properties. Parameters assessed normalized during re-feeding. These results suggest that the impaired mechanical femur competence in ND rats could be due to an altered bone mass and architectural distribution rather than to intrinsic quality. Re-feeding caused a reversal of the effects of food restriction on growth and bone parameters in ND rats.
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