Mimetic gravity: mimicking the dynamics of the primeval universe in the context of loop quantum cosmology

Mimetic gravity can be described as a formulation capable of mimicking different evolutionary scenarios regarding the universe dynamics. Notwithstanding its initial aim of producing a similar evolution to the one expected from the dark components of the standard cosmology, a recent association with loop quantum cosmology could also provide interesting results. In this work, we reinterpret the physics behind the curvature potential of mimetic gravity description of loop quantum cosmology. Furthermore, we also test the compatibility of our formulation for a Higgs-type field, proving that the mimetic curvature potential can mimic the dynamics from a Higgs inflationary model. Additionally, we discuss possible scenarios that emerge from the relationship between matter and mimetic curvature and, within certain limits, describe results for the primeval universe dynamics obtained by other authors.Comment: 13 pages, 2 figure

Spin Liquid Behavior in Electronic Griffiths Phases

We examine the interplay of the Kondo effect and the RKKY interactions in electronic Griffiths phases using extended dynamical mean-field theory methods. We find that sub-Ohmic dissipation is generated for sufficiently strong disorder, leading to suppression of Kondo screening on a finite fraction of spins, and giving rise to universal spin-liquid behavior.Comment: 4 pages, minor changes included, typos correcte

THE IMPACT OF POLLUTION CONTROLS ON LIVESTOCK-CROP PRODUCERS

A discrete-time, continuous-space model of a livestock- crop producer is used to examine the long-run effects of phosphorus runoff controls on optimal livestock production and manure application practices. Quantity restrictions and taxes on phosphorus application are shown to reduce livestock supply and impose greater costs on livestock-crop producers than on crop-only producers. Restrictions on manure application, without accompanying restrictions on commercial fertilizer application, will have only a limited effect on phosphorus runoff levels.Environmental Economics and Policy, Farm Management,

CMB anisotropies induced by tensor modes in Massive Gravity

We study Gravitational Waves (GWs) in the context of Massive Gravity, an extension to General Relativity (GR) where the fluctuations of the metric have a nonzero mass, and specifically investigate the effect of the tensor modes on the Cosmic Microwave Background (CMB) anisotropies. We first study the time evolution of the tensor modes in Massive Gravity and show that there is a graviton mass limit $m_l=10^{-66}g\sim 10^{-29}cm^{-1}$, so that for masses $m\leq m_l$ the tensor perturbations in Massive Gravity are indistinguishable from the corresponding ones in GR. Also, we show that short wavelength massive modes behave almost indistinguishably from their massless counterparts. Later on, we show that massive gravitons with masses within the range $m= 10^{-27}cm^{-1}$ - $m=10^{-26}cm^{-1}$ would leave a clear signature on the lower multipoles ($\ell< 30$) in the CMB anisotropy power spectrum. Hence, our results show that CMB anisotropies measurements might be decisive to show whether the tensor modes are massive or not.Comment: Minor typos corrected and title changed to match the version published by JCA

Effective model of the electronic Griffiths phase

We present simple analytical arguments explaining the universal emergence of electronic Griffiths phases as precursors of disorder-driven metal-insulator transitions in correlated electronic systems. A simple effective model is constructed and solved within Dynamical Mean Field Theory. It is shown to capture all the qualitative and even quantitative aspects of such Griffiths phases.Comment: 9 pages, 7 figures, one reference corrected; minor corrections include

A generalized vortex lattice method for subsonic and supersonic flow applications

If the discrete vortex lattice is considered as an approximation to the surface-distributed vorticity, then the concept of the generalized principal part of an integral yields a residual term to the vorticity-induced velocity field. The proper incorporation of this term to the velocity field generated by the discrete vortex lines renders the present vortex lattice method valid for supersonic flow. Special techniques for simulating nonzero thickness lifting surfaces and fusiform bodies with vortex lattice elements are included. Thickness effects of wing-like components are simulated by a double (biplanar) vortex lattice layer, and fusiform bodies are represented by a vortex grid arranged on a series of concentrical cylindrical surfaces. The analysis of sideslip effects by the subject method is described. Numerical considerations peculiar to the application of these techniques are also discussed. The method has been implemented in a digital computer code. A users manual is included along with a complete FORTRAN compilation, an executed case, and conversion programs for transforming input for the NASA wave drag program