Scalar Field Inhomogeneous Cosmologies

Some exact solutions for the Einstein field equations corresponding to inhomogeneous $G_2$ cosmologies with an exponential-potential scalar field which generalize solutions obtained previously are considered. Several particular cases are studied and the properties related to generalized inflation and asymptotic behaviour of the models are discussed.Comment: 21 pages LaTeX, 3 figures appended as a uuencoded compressed tar fil

On the evolution of a large class of inhomogeneous scalar field cosmologies

The asymptotic behaviour of a family of inhomogeneous scalar field cosmologies with exponential potential is studied. By introducing new variables we can perform an almost complete analysis of the evolution of these cosmologies. Unlike the homogeneous case (Bianchi type solutions), when k^2<2 the models do not isotropize due to the presence of the inhomogeneitiesComment: 23 pages, 1 figure. Submitted to Classical and Quantum Gravit

Multiple Schr\"odinger pictures and dynamics in shortcuts to adiabaticity

A Schr\"odinger equation may be transformed by unitary operators into dynamical equations in different interaction pictures which share with it a common physical frame, i.e., the same underlying interactions, processes and dynamics. In contrast to this standard scenario, other relations are also possible, such as a common interaction-picture dynamical equation corresponding to several Schr\"odinger equations that represent different physics. This may enable us to design alternative and feasible experimental routes for operations that are a priori difficult or impossible to perform. The power of this concept is exemplified by engineering Hamiltonians that improve the performance or make realizable several shortcuts to adiabaticity

Visible-light-promoted iridium(III)-catalyzed acceptorless dehydrogenation of N-Heterocycles at room temperature

An effective visible-light-promoted iridium(III)catalyzed hydrogen production from N-heterocycles is described. A single iridium complex constitutes the photocatalytic system playing a dual task, harvesting visible-light and facilitating C-H cleavage and H-2 formation at room temperature and without additives. The presence of a chelating C-N ligand combining a mesoionic carbene ligand along with an amido functionality in the Ir-III complex is essential to attain the photocatalytic transformation. Furthermore, the le l complex is also an efficient catalyst for the thermal reverse process under mild conditions, positioning itself as a proficient candidate for liquid organic hydrogen carrier technologies (LOHCs). Mechanistic studies support a light-induced formation of H-2 from the Ir-H intermediate as the operating mode of the iridium complex

Relativistic Jets from Collapsars

We have studied the relativistic beamed outflow proposed to occur in the collapsar model of gamma-ray bursts. A jet forms as a consequence of an assumed energy deposition of $\sim 10^{50}- 10^{51}$ erg/s within a $30^{\circ}$ cone around the rotation axis of the progenitor star. The generated jet flow is strongly beamed (\la few degrees) and reaches the surface of the stellar progenitor (r $\approx 3 10^{10}$cm) intact. At break-out the maximum Lorentz factor of the jet flow is about 33. Simulations have been performed with the GENESIS multi-dimensional relativistic hydrodynamic code.Comment: 6 pages, 2 figures, to appear in the proceedings of the conference "Godunov methods: theory and applications", Oxford, October 199

High--Resolution 3D Simulations of Relativistic Jets

We have performed high-resolution 3D simulations of relativistic jets with beam flow Lorentz factors up to 7, a spatial resolution of 8 cells per beam radius, and for up to 75 normalized time units to study the morphology and dynamics of 3D relativistic jets. Our simulations show that the coherent fast backflows found in axisymmetric models are not present in 3D models. We further find that when the jet is exposed to non-axisymmetric perturbations, (i) it does not display the strong perturbations found for 3D classical hydrodynamic and MHD jets (at least during the period of time covered by our simulations), and (ii) it does propagate according to the 1D estimate. Small 3D effects in the relativistic beam give rise to a lumpy distribution of apparent speeds like that observed in M87. The beam is surrounded by a boundary layer of high specific internal energy. The properties of this layer are briefly discussed.Comment: 15 pages, 4 figures. Accepted to be publish in the ApJ Letters. Tar+gzip documen