Results of Evolution Supervised by Genetic Algorithms

A series of results of evolution supervised by genetic algorithms with interest to agricultural and horticultural fields are reviewed. New obtained original results from the use of genetic algorithms on structure-activity relationships are reported.Comment: 6 pages, 1 Table, 2 figure

Einstein-Maxwell-scalar black holes: classes of solutions, dyons and extremality

Spherical black hole (BH) solutions in Einstein-Maxwell-scalar (EMS) models wherein the scalar field is non-minimally coupled to the Maxwell invariant by some coupling function are discussed. We suggest a classification for these models into two classes, based on the properties of the coupling function, which, in particular, allow, or not, the ReissnerNordstr¨om (RN) BH solution of electrovacuum to solve a given model. Then, a comparative analysis of two illustrative families of solutions, one belonging to each class is performed: dilatonic versus scalarised BHs. By including magnetic charge, that is considering dyons, we show that scalarised BHs can have a smooth extremal limit, unlike purely electric or magnetic solutions. In particular, we study this extremal limit using the entropy function formalism, which provides insight on why both charges are necessary for extremal solutions to exist.publishe

Einstein-Yang-Mills solutions in higher dimensional de Sitter spacetime

We consider particle-like and black holes solutions of the Einstein-Yang-Mills system with positive cosmological constant in d>4 spacetime dimensions. These configurations are spherically symmetric and present a cosmological horizon for a finite value of the radial coordinate, approaching asymptotically the de Sitter background. In the usual Yang--Mills case we find that the mass of these solutions, evaluated outside the cosmological horizon at future/past infinity generically diverges for d>4. Solutions with finite mass are found by adding to the action higher order gauge field terms belonging to the Yang--Mills hierarchy. A discussion of the main properties of these solutions and their differences from those to the usual Yang-Mills model, both in four and higher dimensions is presented.Comment: 17 pages, 8 figure

Charged-rotating black holes and black strings in higher dimensional Einstein-Maxwell theory with a positive cosmological constant

We present arguments for the existence of charged, rotating black holes in $d=2N+1$ dimensions, with $d\geq 5$ with a positive cosmological constant. These solutions posses both, a regular horizon and a cosmological horizon of spherical topology and have $N$ equal-magnitude angular momenta. They approach asymptotically the de Sitter spacetime background. The counterpart equations for $d=2N+2$ are investigated, by assuming that the fields are independant of the extra dimension $y$, leading to black strings solutions. These solutions are regular at the event horizon. The asymptotic form of the metric is not the de Sitter form and exhibit a naked singularity at finite proper distance.Comment: 21 pages, 9 figure

Spin-Dependent Tunneling of Single Electrons into an Empty Quantum Dot

Using real-time charge sensing and gate pulsing techniques we measure the ratio of the rates for tunneling into the excited and ground spin states of a single-electron AlGaAs/GaAs quantum dot in a parallel magnetic field. We find that the ratio decreases with increasing magnetic field until tunneling into the excited spin state is completely suppressed. However, we find that by adjusting the voltages on the surface gates to change the orbital configuration of the dot we can restore tunneling into the excited spin state and that the ratio reaches a maximum when the dot is symmetric.Comment: 4 pages, 3 figure