Gravitational Rutherford scattering and Keplerian orbits for electrically charged bodies in heterotic string theory

Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) black hole is presented in this paper. Radial and angular motion are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analysed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys. Rev. D 85: 024033, 2012), Olivares & Villanueva (Eur. Phys. J. C 73: 2659, 2013) and Blaga (Automat. Comp. Appl. Math. 22, 41 (2013); Serb. Astron. J. 190, 41 (2015)) for time-like geodesics.Comment: 11 pages, 12 figure

Massive neutral particles on heterotic string theory

The motion of massive particles in the background of a charged black hole in heterotic string theory, which is characterized by a parameter $\alpha$, is studied in detail in this paper. Since it is possible to write this space-time in the Einstein frame, we perform a quantitative analysis of the time-like geodesics by means of the standard Lagrange procedure. Thus, we obtain and solve a set of differential equations and then we describe the orbits in terms of the elliptic $\wp$-Weierstra{\ss} function. Also, by making an elementary derivation developed by Cornbleet (Am. J. Phys. \textbf{61} 7, (1993) 650 - 651) we obtain the correction to the angle of advance of perihelion to first order in $\alpha$, and thus, by comparing with Mercury's data we give an estimation for the value of this parameter, which yields an {\it heterotic solar charge} $Q_{\odot}\simeq 0.728\,[\textrm{Km}]= 0.493\, M_{\odot}$. Therefore, in addition to the study on null geodesics performed by Fernando (Phys. Rev. D {\bf 85}, (2012) 024033), this work completes the geodesic structure for this class of space-time.Comment: 12 pages, 8 figures. Accepted for publication on EPJ

Geodesic Structure of Lifshitz Black Holes in 2+1 Dimensions

We present a study of the geodesic equations of a black hole space-time which is a solution of the three-dimensional NMG theory and is asymptotically Lifshitz with $z=3$ and $d=1$ as found in [Ayon-Beato E., Garbarz A., Giribet G. and Hassaine M., Phys. Rev. {\bf D} 80, 104029 (2009)]. By means of the corresponding effective potentials for massive particles and photons we find the allowed motions by the energy levels. Exact solutions for radial and non-radial geodesics are given in terms of the Weierstrass elliptic $\wp$, $\sigma$, and $\zeta$ functions.Comment: 10 pages, 6 figures, accepted for publication in Eur. Phys. J.

The golden ratio in Schwarzschild-Kottler black holes

In this paper we show that the golden ratio is present in the Schwarzschild-Kottler metric. For null geodesics with maximal radial acceleration, the turning points of the orbits are in the golden ratio $\Phi = (\sqrt{5}-1)/2$. This is a general result which is independent of the value and sign of the cosmological constant $\Lambda$

The role of non-specific effects in the psychological treatment of adolescents with social phobia

El objetivo de este estudio es analizar los efectos específicos del programa Intervención en Adolescentes con Fobia Social Generalizada (IAFS) junto a los factores inespecíficos de las intervenciones utilizadas en el tratamiento de adolescentes con fobia social (por ejemplo, características del paciente o del terapeuta, expectativas hacia el tratamiento o respecto de la atención y el apoyo prestado por el terapeuta). Para ello, se seleccionan al azar 77 adolescentes y se distribuyen aleatoriamente a cuatro condiciones experimentales: grupo de tratamiento psicológico (paquete multicomponente IAFS), grupo de transmisión de información o educativo, grupo placebo y grupo de control lista de espera. Los resultados muestran la eficacia tanto a corto como a medio plazo (12 meses) del programa IAFS, en las medidas que evalúan directamente las respuestas de ansiedad y en sus correlatos (asertividad, autoestima y adaptación). El grupo placebo también alcanza mejoras importantes en algunas de las variables mencionadas, mientras que el de transmisión de información no obtiene cambios significativos, exceptuando la variable autoestima. Palabras clave: fobia social generalizada, adolescentes, efectos específicos e inespecíficos, experimental.The aim of this study is to analyze the specific effects of the Intervention in Adolescents with Social Phobia (IAFS) program together with the nonspecific factors of the interventions used in the treatment of adolescents with social phobia (for example, characteristics of the patient or the therapist, expectations towards the treatment or the attention and support given by the (therapist). 77 adolescents were selected at random and randomly distributed between four experimental conditions: psychological treatment group (IAFS multicomponent package), transmission of information or educational group, placebo and waiting list control group. The results show the short- and medium-term effectiveness (12 months) of the IAFS according to specific measures assessing social anxiety and avoidance as well as other related constructs (assertiveness, social skills and adjustment). The placebo group achieved important improvements in some of the mentioned conditions, whereas that of information transmission did not obtained significant changes, with the exception of the self-esteem variable. Key words: generalized social phobia, adolescents, specific and nonspecific effects, experimental