49,003 research outputs found
Cosmological coupling of nonsingular black holes
No full textWe show that — in the framework of general relativity (GR) — if black holes (BHs) are singularity-free objects, they couple to the large-scale cosmological dynamics. We find that the leading contribution to the resulting growth of the BH mass (M BH) as a function of the scale factor a stems from the curvature term, yielding M BH ∝ ak , with k = 1. We demonstrate that such a linear scaling is universal for spherically-symmetric objects, and it is the only contribution in the case of regular BHs. For nonsingular horizonless compact objects we instead obtain an additional subleading model-dependent term. We conclude that GR nonsingular BHs/horizonless compact objects, although cosmologically coupled, are unlikely to be the source of dark energy. We test our prediction with astrophysical data by analysing the redshift dependence of the mass growth of supermassive BHs in a sample of elliptical galaxies at redshift z = 0.8-0.9. We also compare our theoretical prediction with higher redshift BH mass measurements obtained with the James Webb Space Telescope (JWST). We find that, while k = 1 is compatible within 1σ with JWST results, the data from elliptical galaxies at z = 0.8-0.9 favour values of k > 1. New samples of BHs covering larger mass and redshift ranges and more precise BH mass measurements are required to settle the issue
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
Gli enzimi proteolitici nel trattamento delle flogosi di pertinenza otorinolaringoiatrica. Serratiopeptidasi e Seaprose-S
No full textTwo-dimensional black holes as open strings: a new realization of the ADS/CFT correspondence
No full textWe show that weak-coupled two-dimensional dilation gravity on anti-de Sitter space can be described by the dynamics of an open string. Neumann and Dirichlet boundary conditions for the string lead two different realizations of the anti-de Sitter/Conformal Field Theory correspondence. In particular, in the Dirichlet case the thermodynamical entropy of two-dimensional black holes can be exactly reproduced by counting the string states
BPS-like bound and thermodynamics of the charged BTZ black hole
No full textThe charged Bañados-Teitelboim-Zanelli (BTZ) black hole is plagued by several pathologies: (a) Divergent boundary terms are present in the action; hence, we have a divergent black-hole mass. (b) Once a finite, renormalized, mass M is defined, black-hole states exist for arbitrarily negative values of M. (c) There is no upper bound on the charge Q. We show that these pathological features are an artifact of the renormalization procedure. They can be completely removed by using an alternative renormalization scheme leading to a different definition M0 of the black-hole mass, which is the total energy inside the horizon. The new mass satisfies a BPS-like bound M0≥π/2Q2, and the heat capacity of the hole is positive. We also discuss the black-hole thermodynamics that arises when M0 is interpreted as the internal energy of the system. We show, using three independent approaches (black-hole thermodynamics, Einstein equations, and Euclidean action formulation), that M0 satisfies the first law if a term describing the mechanical work done by the electrostatic pressure is introduced
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
On The Hydrothermal Stability Of Cuapso-34 Microporous Catalysts For N 2o Decomposition: A Comparison With Cuzsm-5
No full textThe hydrothermal stability of CuAPSO-34 microporous silicoaluminophosphates with chabasite structures has been investigated and compared to that of a copper-exchanged ZSM-5 zeolite by a combined XRD, FTIR, and catalytic study. CuAPSO-34 showed a higher hydrothermal structural stability (steaming 80 h at 600°C), as found by XRD. Spectroscopic FTIR investigation of adsorbed CO revealed that upon this steaming procedure the concentration of monovalent copper ions in CuAPSO-34 was not significantly affected, whereas, even after a less severe steaming (60 h at 550°C), these species dramatically decreased in CuZSM-5, and extraframework Al3+ ions were simultaneously formed. Consequently, the high activity in N 2O decomposition shown by fresh CuZSM-5 was essentially lost after steaming, while CuAPSO-34 exhibited a significantly milder deactivation. © 2003 Elsevier Science (USA). All rights reserved.2171100106Centi, G., Galli, A., Montanari, B., Perathoner, S., Vaccari, A., (1997) Catal. Today, 35, p. 113Werther, J., Ogada, T., Philippek, C., (1995) Proc. of 6th Internat. Workshop on Nitrous oxide Emission, Turku, Finland, p. 139Riley, B.W., Richmond, J.R., (1993) Catal. Today, 17, p. 277Berges, M., Hoffmann, R., Scharffe, D., Crutzen, P., (1993) J. Geophys. Res., 98, p. 18527Yuzaki, K., Yarimizu, T., Aoyagi, K., Ito, S., Kunimori, K., (1998) Catal. Today, 45, p. 129Yuichi, O., Kazushi, K., Ming, B., Tatsuo, M., (1999) J. Chem. Phys. B, 110, p. 8221Subramanian, S., Swamy, C.S., (1995) Catal. Lett., 35, p. 361Gao, L.Z., Au, C.T., (2001) Appl. Catal. B, 30, p. 35Kannan, S., Swamy, C.S., (1994) Appl. Catal. B, 3, p. 109Armor, J.N., Braymer, T.A., Farris, T.S., Li, Y., Petrocelli, F., Weist, E.L., Kannan, S., Swamy, C.S., (1996) Appl. Catal. B, 7, p. 397Kapteijn, F., Rodriguez-Mirasol, J., Moulijn, J.A., (1996) Appl. Catal. B, 9, p. 25Pârvulescu, V.I., Grange, P., Delmon, B., (1998) Catal. Today, 46, p. 233Dandekar, A., Vannice, M.A., (1999) Appl. Catal. B, 22, p. 179Schay, Z., Guczi, L., Beck, A., Nagy, I., Samuel, V., Mirajkar, S.P., Ramaswamy, A.V., Pál-Borbély, G., (2002) Catal. Today, 75, p. 393Armor, J.N., (1998) Micropor. Mesopor. Mater., 22, p. 451Traa, Y., Burger, B., Weitkamp, J., (1999) Micropor. Mesopor. Mater., 30, p. 3Kucherov, A.V., Hubbard, C.P., Kucherova, T.N., Shelef, M., (1997) Kinet. Catal., 38, p. 607Chajar, Z., Denton, P., Berthet de Bernard, F., Primet, M., Praliaud, H., (1998) Catal. Lett., 55, p. 217Zhang, Y., Flytzani-Stephanopoulos, M., (1996) J. Catal., 164, p. 131Watanabe, Y., Koiwai, A., Takeuchi, H., Hyodo Shi-Aki, Noda, S., (1993) J. Catal., 143, p. 430Wilson, S.T., Lok, B.M., Messina, C.A., Cannan, T.R., Flanigen, E.M., (1982) J. Am. Chem. Soc., 104, p. 1146Marchese, L., Frache, A., Gatti, G., Coluccia, S., Lisi, L., Ruoppolo, G., Russo, G., Pastore, H.O., (2002) J. Catal., 208, p. 479Frache, A., Palella, B., Cadoni, M., Pirone, R., Ciambelli, P., Pastore, H.O., Marchese, L., (2002) Catal. Today, 75, p. 359Frache, A., Palella, B., Cadoni, M., Pirone, R., Pastore, H.O., Marchese, L., (2002) Top. Catal., p. 53Hartmann, M., Kevan, L., (1999) Chem. Rev., 99, p. 635Stöcker, M., (1999) Micropor. Mesopor. Mater., 29, p. 3Ishihara, T., Kagawa, M., Mizuhara, Y., Takita, Y., (1992) Chem. Lett., p. 2119Panayotov, D., Dimitrov, L., Khristova, M., Petrov, L., Mehandjiev, D., (1995) Appl. Catal. B, 6, p. 61Ishihara, T., Kagawa, M., Hadama, F., Takita, Y., (1997) J. Catal., 169, p. 93Ishihara, T., Kagawa, M., Hadama, F., Nishiguchi, H., Ito, M., Takita, Y., (1997) Ind. Eng. Chem. Res., 36, p. 17Dedecek, J., Čejka, J., Wichterlova, B., (1998) Appl. Catal. B, 15, p. 233Marchese, L., Gianotti, E., Palella, B., Pirone, R., Martra, G., Coluccia, S., Ciambelli, P., (2000) Stud. Surf. Sci. Catal., 130 C, p. 3005Gianotti, E., Marchese, L., Martra, G., Coluccia, S., (1999) Catal. Today, 54, p. 547Akolekar, D.B., Bhargava, S.K., Foger, K., (1999) J. Chem. Soc., Faraday Trans., 94, p. 155Akolekar, D.B., Bhargava, S.K., (2000) J. Mol. Catal. A, 157, p. 199Frache, A., Cadoni, M., Coluccia, S., Marchese, L., Palella, B., Pirone, R., Ciambelli, P., (2001) Stud. Surf. Sci. Catal., 135, p. 328Frache, A., Marchese, L., Cadoni, M., Coluccia, S., Palella, B., Pirone, R., Ciambelli, P., (2001) Stud. Surf. Sci. Catal., 140, p. 269Briend, M., Vomscheid, R., Peltre, M.J., Man, P.P., Barthomeuf, D., (1995) J. Phys. Chem., 99, p. 8270Iwamoto, M., Hamada, H., (1991) Catal. Today, 10, p. 57Aylor, A.W., Larsen, S.C., Reimer, J.A., Bell, A.T., (1995) J. Catal., 157, p. 592Spoto, G., Zecchina, A., Bordiga, S., Ricchiardi, G., Martra, G., Leofanti, G., Petrini, G., (1994) Appl. Catal. B, 3, p. 151Trout, B.L., Chakraborty, A.K., Bell, A.T., (1996) J. Phys. Chem. B, 100, p. 17582Bell, A.T., (1997) Catal. Today, 38, p. 151Lamberti, C., Bordiga, S., Salvalaggio, M., Spoto, G., Zecchina, A., (1997) J. Phys. Chem. B, 101-103, p. 344Zecchina, A., Bordiga, S., Salvalaggio, M., Spoto, G., Scarano, D., Lamberti, C., (1998) J. Catal., 173, p. 540Datka, J., Gil, B., Kawalek, M., Staudte, B., (1999) J. Mol. Struct., 511, p. 133Dedecek, J., Wichterlova, B., Kubat, P., (1999) Micropor. Mesopor. Mater., 32, p. 63Nachtigallova, D., Nachtigall, P., Sauer, J., (2001) Phys. Chem. Chem. Phys., 3, p. 1552Kucherov, A.V., Hubbard, C.P., Shelef, M., (1995) J. Catal., 157, p. 603Kharas, K.C.C., Robota, H.J., Liu, D.J., (1993) Appl. Catal. B, 2, p. 225Iwamoto, M., Wang, J., Sperati, K.M., Sajiki, T., Misono, M., (1997) Chem. Lett., p. 1281Yan, J.Y., Lei, G.D., Sachtler, W.M., Kung, H.H., (1996) J. Catal., 161, p. 4
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Order-disorder character and twinning in the structure of a new synthetic titanosilicate: (Ba,Sr)4Ti6Si4O24.H2O
No full text- …
