On the Space Time of a Galaxy

We present an exact solution of the averaged Einstein's field equations in the presence of two real scalar fields and a component of dust with spherical symmetry. We suggest that the space-time found provides the characteristics required by a galactic model that could explain the supermassive central object and the dark matter halo at once, since one of the fields constitutes a central oscillaton surrounded by the dust and the other scalar field distributes far from the coordinate center and can be interpreted as a halo. We show the behavior of the rotation curves all along the background. Thus, the solution could be a first approximation of a ``long exposition photograph'' of a galaxy.Comment: 8 pages REVTeX, 11 eps figure

Innovation of Coagulation-Flocculation Processes Using Biopolyelectrolytes and Zeta Potential for Water Reuse

The coagulation-flocculation process is one of the conventional technologies used for the treatment of different types of industrial wastewater. The zeta potential is a key parameter that allows to determine the effective pH, the type and the correct biopolyelectrolyte dose to return the water quality using coagulation-flocculation. In this chapter, we present the application of a natural cationic biopolyelectrolyte (chitosan) to make the separation and recovery of cellulose fiber more efficient and to increase the reuse of treated water from the pulp and paper industry. The result of the coagulation-flocculation test at pH 5.4 and a chitosan dose = 10 mg/L shows that the treated water has the following values: biochemical oxygen demand = 150 mg O2/L, turbidity = 5 FAU, total suspended solids = 2 mg/L, chemical oxygen demand = 200 mg/L and hardness = 250 mg CaCO3/L. The quality of water obtained allows its discharge to a natural water body, in which it is possible to continue with a biological treatment stage, or to reuse the treated water for the manufacture of paper. Additionally, this coagulation-flocculation process can be coupled to an advanced oxidation process to increase the quality of the water and mineralize the content of organic material

All-inclusive tourism in Dominican Republic. An analysis from the perspective of the tourist demand

All Inclusive System has become a predominant service in sun and beach destinations. In Dominican Republic it is set as the main tourist attraction. The purpose of this research is to analyze the ratings of “all inclusive” international tourists that reach the tourist resort of Puerto Plata. This research is based on the responses obtained from of a questionnaire completed by foreign visitors. The main results show that tourists are a medium-high economic profile highlighting those visitors who choose this destination online. The beaches and ease of entry are the most highly valued

Quintessence and Scalar Dark Matter in the Universe

Continuing with previous works, we present a cosmological model in which dark matter and dark energy are modeled by scalar fields $\Phi$ and $\Psi$, respectively, endowed with the scalar potentials $V(\Phi)=V_{o}[ \cosh {(\lambda \sqrt{\kappa_{o}}\Phi)}-1]$ and $\tilde{V}(\Psi)=\tilde{V_{o}}[ \sinh {(\alpha \sqrt{\kappa_{o}}\Psi)}] ^{\beta}$. This model contains 95% of scalar field. We obtain that the scalar dark matter mass is $m_{\Phi}\sim 10^{-26}eV.$ The solution obtained allows us to recover the success of the standard CDM. The implications on the formation of structure are reviewed. We obtain that the minimal cutoff radio for this model is $r_{c}\sim 1.2 kpc.$Comment: 4 pages REVTeX, 3 eps color figures. Minor changes and references updated. To appear in Classical and Quantum Gravity as a Letter to the Editor. More information at http://www.fis.cinvestav.mx/~siddh/PHI

Scalar Field as Dark Matter in the Universe

We investigate the hypothesis that the scalar field is the dark matter and the dark energy in the Cosmos, wich comprises about 95% of the matter of the Universe. We show that this hypothesis explains quite well the recent observations on type Ia supernovae.Comment: 4 pages REVTeX, 1 eps figure. Minor changes. To appear in Classical and Quantum Gravit

Oscillatons revisited

In this paper, we study some interesting properties of a spherically symmetric oscillating soliton star made of a real time-dependent scalar field which is called an oscillaton. The known final configuration of an oscillaton consists of a stationary stage in which the scalar field and the metric coefficients oscillate in time if the scalar potential is quadratic. The differential equations that arise in the simplest approximation, that of coherent scalar oscillations, are presented for a quadratic scalar potential. This allows us to take a closer look at the interesting properties of these oscillating objects. The leading terms of the solutions considering a quartic and a cosh scalar potentials are worked in the so called stationary limit procedure. This procedure reveals the form in which oscillatons and boson stars may be related and useful information about oscillatons is obtained from the known results of boson stars. Oscillatons could compete with boson stars as interesting astrophysical objects, since they would be predicted by scalar field dark matter models.Comment: 10 pages REVTeX, 10 eps figures. Updated files to match version published in Classical and Quantum Gravit

Newtonian Collapse of Scalar Field Dark Matter

In this letter, we develop a Newtonian approach to the collapse of galaxy fluctuations of scalar field dark matter under initial conditions inferred from simple assumptions. The full relativistic system, the so called Einstein-Klein-Gordon, is reduced to the Schr\"odinger-Newton one in the weak field limit. The scaling symmetries of the SN equations are exploited to track the non-linear collapse of single scalar matter fluctuations. The results can be applied to both real and complex scalar fields.Comment: 4 pages RevTex4 file, 4 eps figure

Culinary tourism as a cultural experience. the case study of the city of Cáceres (Spain)

Texto resumen

Physicochemical Insights of the Organic Matter Particles Dispersed in Wastewaters Induced by Bio-Polyelectrolytes

The turbidity and color of the water are mainly caused by colloidal particles. These particles remain in suspension for a long time and can even pass through a very fine filter medium, since they do not have a tendency to agglomerate. Due to this, polyelectrolytes such as chitosan have been used in coagulation-flocculation processes because they dissociate into charged species in solution and these contribute to charges or dissociable groups which are covalently bound to its structure. With the zeta potential measurements (ζ) vs. pH and particle size, the ideal dose of bio-polyelectrolyte was determined with which, the isoelectric point (IEP) was reached, generating electroneutrality in the system, removing 92% of the chemical oxygen demand (COD). The results discussed here represent a sustainable alternative to the water reuse and sanitation problem of the fish processing industry. The use of bio-polyelectrolytes offers that the by-products obtained from the coagulation-flocculation process can be reused and recovered for other uses