The Three-Dimensional BTZ Black Hole as a Cylindrical System in Four-Dimensional General Relativity

It is shown how to transform the three dimensional BTZ black hole into a four dimensional cylindrical black hole (i.e., black string) in general relativity. This process is identical to the transformation of a point particle in three dimensions into a straight cosmic string in four dimensions.Comment: Latex, 9 page

Influence of chlorhexidine and zinc oxide in calcium hydroxide pastes on pH changes in external root surface

The objective of this study was to assess the influence of chlorhexidine (liquid and gel) and zinc oxide in calcium hydroxide (CH) pastes on root pH in simulated external resorption. One hundred human anterior teeth with a single root canal were selected. After decoronation and root canal instrumentation, the specimens were divided into 4 experimental groups and 1 control group (without intracanal paste): CH + saline (CH+S), CH + 2% chlorhexidine liquid (CH+ CHX), CH + 2% chlorhexidine gel (CH+ CHXg), and CH + 2% chlorhexidine gel + zinc oxide (CH+ CHXg+ZnO). pH was measured using a microelectrode at 3 and 24 h, and 1, 2, 3, and 4 weeks after inserting intracanal pastes. Data were analyzed statistically using an ANOVA and Tukey's test (p < 0.05). The CH+CHXg+ZnO group had the highest pH values throughout (p < 0.05). The CH+S and CH+ CHX groups had the highest pH values after 1 week and the CH+ CHXg group after 2 weeks. CH+ CHXg maintained the highest pH until the fourth week compared with CH+ CHX (p < 0.05). The control group remained at a neutral pH at all evaluated times. It can be concluded that chlorhexidine solution or gel maintained the alkaline pH of CH, and chlorhexidine gel allowed a slower decrease in pH over time. CH+ CHXg+ZnO showed the highest pH values and was an effective intracanal medication for maintaining alkaline root pH in the area of resorption3

Distributional range, ecology, and mating system of the Cape mole-rat (Georychus capensis) family Bathyergidae

Abstract: Interpopulation variation in life-history patterns are influenced by intrinsic and extrinsic factors. Life-history patterns have been intensely studied in the eusocial African bathyergid species, largely neglecting the solitary species. Of these solitary genera, the Cape mole-rat (Georychus capensis (Pallas, 1778)) is endemic to South Africa with a disjunct distribution across its range. Knowledge regarding this species is rudimentary; therefore, this study aimed to investigate the current distribution of the species with particular attention to common ecological variables, differences in body size between localities and sexes, as well as its reproduction and mating system. Georychus is a habitat specialist restricted to specific ecological areas. A lack of sexual size dimorphism and correlation between male testis size and number of females in the population, suggests a polygynous mating system, facilitated by the spatial distribution of the sexes. A positive relationship between male testes size and percentage of females in populations sampled suggests that larger sperm reserves (i.e., larger testes) are required in populations with a higher percentage of females. In addition, mating variables (testicular size and litter size) are linked to ecological factors (elevation, aridity, soil type, and vegetation type) that could impact mate searching, mating success, and food resources

Horizonless Rotating Solutions in (n+1)(n+1)-dimensional Einstein-Maxwell Gravity

We introduce two classes of rotating solutions of Einstein-Maxwell gravity in $n+1$ dimensions which are asymptotically anti-de Sitter type. They have no curvature singularity and no horizons. The first class of solutions, which has a conic singularity yields a spacetime with a longitudinal magnetic field and $k$ rotation parameters. We show that when one or more of the rotation parameters are non zero, the spinning brane has a net electric charge that is proportional to the magnitude of the rotation parameters. The second class of solutions yields a spacetime with an angular magnetic field and $$ boost parameters. We find that the net electric charge of these traveling branes with one or more nonzero boost parameters is proportional to the magnitude of the velocity of the brane. We also use the counterterm method inspired by AdS/CFT correspondence and calculate the conserved quantities of the solutions. We show that the logarithmic divergencies associated to the Weyl anomalies and matter field are zero, and the $r$ divergence of the action can be removed by the counterterm method.Comment: 14 pages, references added, Sec. II amended, an appendix added. The version to appear in Phys. Rev.

Wormholes and Ringholes in a Dark-Energy Universe

The effects that the present accelerating expansion of the universe has on the size and shape of Lorentzian wormholes and ringholes are considered. It is shown that, quite similarly to how it occurs for inflating wormholes, relative to the initial embedding-space coordinate system, whereas the shape of the considered holes is always preserved with time, their size is driven by the expansion to increase by a factor which is proportional to the scale factor of the universe. In the case that dark energy is phantom energy, which is not excluded by present constraints on the dark-energy equation of state, that size increase with time becomes quite more remarkable, and a rather speculative scenario is here presented where the big rip can be circumvented by future advanced civilizations by utilizing sufficiently grown up wormholes and ringholes as time machines that shortcut the big-rip singularity.Comment: 11 pages, RevTex, to appear in Phys. Rev.

Raman Phonon Modes Of Zinc Blende Inxga1 - Xn Alloy Epitaxial Layers

Transverse-optical (TO) and longitudinal-optical (LO) phonons of zinc blende InxGa1 - xN (0≤x ≤0.31) layers are observed through first-order micro-Raman scattering experiments. The samples are grown by molecular-beam epitaxy on GaAs (001) substrates, and x-ray diffraction measurements are performed to determine the epilayer alloy composition. Both the TO and LO phonons exhibit a one-mode-type behavior, and their frequencies display a linear dependence on the composition. The Raman data reported here are used to predict the A1 (TO) and E1 (TO) phonon frequencies of the hexagonal InxGa1 - xN alloy. © 1999 American Institute of Physics.75810951097Pankove, J.I., Moustakas, T., Gallium nitrides I (1998) Semiconductors and Semimetals, 50. , Academic, San Diego, CAShan, W., Walukiewicz, W., Haller, E.E., Little, B.D., Song, J.J., McCluskey, M.D., Johnson, N.M., Stall, R.A., (1998) J. Appl. Phys., 84, p. 4452Chichibu, S., Azuhata, T., Sota, T., Nakamura, S., (1997) Appl. Phys. Lett., 70, p. 2822Shan, W., Perlin, P., Ager J.W. III, Walukiewicz, W., Haller, E.E., McCluskey, M.D., Johnson, N.M., Bour, D.P., (1998) Appl. Phys. Lett., 73, p. 1613Chichibu, S., Azuhata, T., Sota, T., Nakamura, S., (1996) Appl. Phys. Lett., 69, p. 4188Narukawa, Y., Kawakami, Y., Funato, M., Fujita, S., Nakamura, S., (1997) Appl. Phys. Lett., 70, p. 981Orton, J.W., Foxon, C.T., (1998) Rep. Prog. Phys., 61, p. 1Abernathy, C.R., MacKenzie, J.D., Bharatan, S.R., Jones, K.S., Pearton, S.J., (1995) Appl. Phys. Lett., 66, p. 1632(1995) J. Vac. Sci. Technol. A, 13, p. 716Müllhäuser, J.R., Jenichen, B., Wassermeier, M., Brandt, O., Ploog, K.H., (1997) Appl. Phys. Lett., 71, p. 909Müllhäuser, J.R., Brandt, O., Trompert, A., Jenichen, B., Ploog, K.H., (1998) Appl. Phys. Lett., 73, p. 1230Holst, J., Hoffmann, A., Broser, I., Frey, T., Schöttker, B., As, D.J., Schikora, D., Lischka, K., (1999) MRS Internet J. Nitride Semicond. Res., 4 S1, pp. G23Feng, Z.C., Schurman, M., Tran, C.A., Salagaj, T., Karlicek, B., Ferguson, I., Stall, R.A., Pitt, G.D., (1998) Mater. Sci. Forum, 264-268, p. 1359Behr, D., Niebuhr, R., Obloh, H., Wagner, J., Bachem, K.H., Kaufmann, U., (1997) Mater. Res. Soc. Symp. Proc., 468, p. 213Osamura, K., Naka, S., Murakami, Y., (1975) J. Appl. Phys., 46, p. 3432Tabata, A., Lima, A.P., Teles, L.K., Scolfaro, L.M.R., Leite, J.R., Lemos, V., Schöttker, B., Lischka, K., (1999) Appl. Phys. Lett., 74, p. 362Tabata, A., Enderlein, R., Leite, J.R., Da Silva, S.W., Galzerani, J.C., Schikora, D., Kloidt, M., Lischka, K., (1996) J. Appl. Phys., 79, p. 4137Strite, S., Chandrasekhar, D., Smith, D.J., Sariel, J., Chen, H., Teraguchi, N., Morkoç, H., (1993) J. Cryst. Growth, 127, p. 204Ho, I., Stringfellow, G.B., (1996) Appl. Phys. Lett., 69, p. 2701Inushima, T., Yaguchi, T., Nagase, A., Iso, A., Shiraishi, T., (1996) Proceedings of the 6th Conference on Silicon Carbide and Related Materials, , Bristol(1996) Inst. Phys. Conf. Ser., 142, p. 971Dyck, J.S., Kash, K., Kim, K., Lambrecht, W.R.L., Hayman, C.C., Argoitia, A., Grossner, M.T., Angus, J.C., (1998) Mater. Res. Soc. Symp. Proc., 482, p. 549Yu, S., Kim, K.W., Bergman, L., Dutta, M., Stroscio, M.A., Zavada, J.M., (1998) Phys. Rev. B, 58, p. 15283Kwon, H.-J., Lee, Y.-H., Miki, O., Yamano, H., Yoshida, A., (1996) Appl. Phys. Lett., 69, p. 937Lee, M.-C., Lin, H.-C., Pan, Y.-C., Shu, C.-K., Ou, J., Chen, W.-H., Chen, W.-K., (1998) Appl. Phys. Lett., 73, p. 260

Rotating Black Branes in the presence of nonlinear electromagnetic field

In this paper, we consider a class of gravity whose action represents itself as a sum of the usual Einstein-Hilbert action with cosmological constant and an $U(1)$ gauge field for which the action is given by a power of the Maxwell invariant. We present a class of the rotating black branes with Ricci flat horizon and show that the presented solutions may be interpreted as black brane solutions with two event horizons, extreme black hole and naked singularity provided the parameters of the solutions are chosen suitably. We investigate the properties of the solutions and find that for the special values of the nonlinear parameter, the solutions are not asymptotically anti-deSitter. At last, we obtain the conserved quantities of the rotating black branes and find that the nonlinear source effects on the electric field, the behavior of spacetime, type of singularity and other quantities.Comment: 7 pages, 5 figures, to appear in EPJ