Generalized Chaplygin Gas, Accelerated Expansion and Dark Energy-Matter Unification

We consider the scenario emerging from the dynamics of a generalized $d$-brane in a $(d+1, 1)$ spacetime. The equation of state describing this system is given in terms of the energy density, $\rho$, and pressure, $p$, by the relationship $p = - A/\rho^{\alpha}$, where $A$ is a positive constant and $0 < \alpha \le 1$. We discuss the conditions under which homogeneity arises and show that this equation of state describes the evolution of a universe evolving from a phase dominated by non-relativistic matter to a phase dominated by a cosmological constant via an intermediate period where the effective equation of state is given by $p = \alpha \rho$.Comment: 5 pages, 4 figures, revte

A Further Analysis of a Cosmological Model of Quintessence and Scalar Dark Matter

We present the complete solution to a 95% scalar field cosmological model in which the dark matter is modeled by a scalar field $\Phi$ with the scalar potential $V(\Phi)=V_{o}[ \cosh {(\lambda \sqrt{\kappa_{o}}\Phi)}-1]$ and the dark energy is modeled by a scalar field $\Psi$, endowed with the scalar potential $\tilde{V}(\Psi)=\tilde{V_{o}}[ \sinh {(\alpha \sqrt{\kappa_{o}}\Psi)}] ^{\beta}$. This model has only two free parameters, $\lambda$ and the equation of state $\omega_{\Psi}$. With these potentials, the fine tuning and the cosmic coincidence problems are ameliorated for both dark matter and dark energy and the models agrees with astronomical observations. For the scalar dark matter, we clarify the meaning of a scalar Jeans lenght and then the model predicts a suppression of the Mass Power Spectrum for small scales having a wave number $k > k_{min,\Phi}$, where $k_{min,\Phi} \simeq 4.5 h {\rm Mpc}^{-1}$ for $\lambda \simeq 20.28$. This last fact could help to explain the dearth of dwarf galaxies and the smoothness of galaxy core halos. From this, all parameters of the scalar dark matter potential are completely determined. The dark matter consists of an ultra-light particle, whose mass is $m_{\Phi} \simeq 1.1\times 10^{-23} {\rm eV}$ and all the success of the standard cold dark matter model is recovered. This implies that a scalar field could also be a good candidate as the dark matter of the Universe.Comment: 11 pages REVTeX, 6 eps color figures. More information at http://www.fis.cinvestav.mx/~siddh/PHI/. Revised version. New results added and changes made in response to referee comment

Quintessence arising from exponential potentials

We demonstrate how exponential potentials that could arise in the early Universe as a result of Kaluza-Klein type compactifications of string theory, can lead to cosmological solutions which correspond to the currently observed accelerating Universe. The idea is simple, relying solely on the known scaling properties associated with exponential potentials. In particular we show that the existence of stable attractor solutions implies that the results hold for a wide range of coupling constants and initial conditions.Comment: 4 pages, 3 figures, published versio

Green manure in coffee systems in the region of Zona da Mata, Minas Gerais: characteristics and kinetics of carbon and nitrogen mineralization.

The use of green manure may contribute to reduce soil erosion and increase the soil organic matter content and N availability in coffee plantations in the Zona da Mata, State of Minas Gerais, in Southeastern Brazil. The potential of four legumes (A. pintoi, C. mucunoides, S. aterrimum and S. guianensis)to produce above-ground biomass, accumulate nutrients and mineralize N was studied in two coffee plantations of subsistence farmers under different climate conditions. The biomass production of C. mucunoides was influenced by the shade of the coffee plantation.C. mucunoides tended to mineralize more N than the other legumes due to the low polyphenol content and polyphenol/N ratio. In the first year, the crop establishment of A. pintoi in the area took longer than of the other legumes, resulting in lower biomass production and N2 fixation. In the long term, cellulose was the main factor controlling N mineralization. The biochemical characteristics, nutrient accumulation and biomass production of the legumes were greatly influenced by the altitude and position of the area relative to the sun

Planck-scale quintessence and the physics of structure formation

In a recent paper we considered the possibility of a scalar field providing an explanation for the cosmic acceleration. Our model had the interesting properties of attractor-like behavior and having its parameters of O(1) in Planck units. Here we discuss the effect of the field on large scale structure and CMB anisotropies. We show how some versions of our model inspired by "brane" physics have novel features due to the fact that the scalar field has a significant role over a wider range of redshifts than for typical "dark energy" models. One of these features is the additional suppression of the formation of large scale structure, as compared with cosmological constant models. In light of the new pressures being placed on cosmological parameters (in particular H_0) by CMB data, this added suppression allows our "brane" models to give excellent fits to both CMB and large scale structure data.Comment: 18 pages, 12 figures, submitted to PR

A Coulomb gas approach to the anisotropic one-dimensional Kondo lattice model at arbitrary filling

We establish a mapping of a general spin-fermion system in one dimension into a classical generalized Coulomb gas. This mapping allows a renormalization group treatment of the anisotropic Kondo chain both at and away from half-filling. We find that the phase diagram contains regions of paramagnetism, partial and full ferromagnetic order. We also use the method to analyze the phases of the Ising-Kondo chain.Comment: 19 pages, 9 figure

tumor infiltrating lymphocytes tils and pdl1 expression as prescreening enrichment biomarkers of clinical benefit to immune checkpoint inhibitors ci in early clinical trials ect

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