Estaquia em espécies cítricas monoembriônicas autoincompatíveis: uma alternativa para a caracterização citogenética de variedades do Banco Ativo de Germoplasma (BAG) de Citros.

O gênero Citrus L. (família Rutaceae) é formado tipicamente por espécies poliembriônicas, cujas sementes apresentam um embrião zigótico (híbrido) e um ou vários nucelares (apomíticos). Entretanto, alguns representantes deste grupo são monoembriônicos e autoincompatíveis, fato que leva à formação de seedlings exclusivamente de origem híbrida

Some remarks on the attractor behaviour in ELKO cosmology

Recent results on the dynamical stability of a system involving the interaction of the ELKO spinor field with standard matter in the universe have been reanalysed, and the conclusion is that such system does not exhibit isolated stable points that could alleviate the cosmic coincidence problem. When a constant parameter $\delta$ related to the potential of the ELKO field is introduced in the system however, stable fixed points are found for some specific types of interaction between the ELKO field and matter. Although the parameter $\delta$ is related to an unknown potential, in order to satisfy the stability conditions and also that the fixed points are real, the range of the constant parameter $\delta$ can be constrained for the present time and the coincidence problem can be alleviated for some specific interactions. Such restriction on the ELKO potential opens possibility to apply the ELKO field as a candidate to dark energy in the universe, and so explain the present phase of acceleration of the universe through the decay of the ELKO field into matter.Comment: 17 pages, section III with minor changes and section IV rewritten with a new analysi

Flatness-based control of a single qubit gate

This work considers the open-loop control problem of steering a two level quantum system from an initial to a final condition. The model of this system evolves on the state space SU(2), having two inputs that correspond to the complex amplitude of a resonant laser field. A symmetry preserving flat output is constructed using a fully geometric construction and quaternion computations. Simulation results of this flatness-based open-loop control are provided.Comment: Submitted to IEEE AC. Simulation code available at http://cas.ensmp.fr/~rouchon/publications/PR2007/CodeMatlabScilabQubit.zi

Constructive summation of the (2,2) quasi normal mode from a population of black holes

The quasi normal modes (QNMs) associated with gravitational-wave signals from binary black hole (BBH) mergers can provide deep insight into the remnant's properties. Once design sensitivity is achieved, present ground-based gravitational wave interferometers could detect potentially hundreds of BBH signals in the coming years. For most, the ringdown phase will have a very weak signal-to-noise ratio (SNR). Signal summation techniques allow information extraction from the weak SNR ringdowns. We propose a method to constructively sum the (2,2) QNM from different BBH signals by synchronizing and rescaling them. The parameter space adopted to test the method is presently limited to mass ratio $q\leq3$, initially non-spinning black holes with face-on orientation. Moreover, since the synchronisation procedure fails for the weakest signals, we select all ringdowns with SNR above 2.6. Under these conditions, we show that for different BBH populations, 40 to 70% of all the potential detections could be used for the summation while still ensuring a summed SNR of $\sim$80% of the maximal achievable SNR (i.e. for ideally synchronized signals).Comment: 7 pages, 10 figure