Primordial black hole production during preheating in a chaotic inflationary model

In this paper we review the production of primordial black holes (PBHs) during preheating after a chaotic inflationary model. All relevant equations of motion are solved numerically in a modified version of HLattice, and we then calculate the mass variance to determine structure formation during preheating. It is found that production of PBHs can be a generic result of the model, even though the results seem to be sensitive to the values of the smoothing scale. We consider a constraint for overproduction of PBHs that could uncover some stress between inflation-preheating models and observations.Comment: 6 pages, 5 figures. Prepared for the conference proceedings of the 9th Mexican School on Gravitation and Mathematical Physics : Cosmology for the XXI Century: Inflation, Dark Matter and Dark Energ

Analytical approximations to the spectra of quark-antiquark potentials

A method, recently devised to obtain analytical approximations to certain classes of integrals, is used in combination with the WKB expansion to derive accurate analytical expressions for the spectrum of quantum potentials. The accuracy of our results is verified by comparing them both with the literature on the subject and with the numerical results obtained with a Fortran code. As an application of the method that we propose, we consider the meson spectroscopy with various phenomenological potentials.Comment: 12 pages, 4 figures, 1 tabl

Cosmological constraints for a two brane-world system with single equation of state

We present the study of two 3-brane system embedded in a 5-dimensional space-time in which the fifth dimension is compactified on a $S^{1}/Z_{2}$ orbifold. Assuming isotropic, homogeneous, and static branes, it can be shown that the dynamics of one brane is dominated by the other one when the metric coefficients have a particular form. We study the resulting cosmologies when one brane is dominated by a given single-fluid component.Comment: This work was presented at the VIII Taller of the DGFM, Tuxtla Gutierrez, Chiapas, Mexico noviembre 22-26, 201

Roles of lipids in coconut (Cocos nucifera L.) embryogenesis

The coconut palm (Cocos nucifera L.) is an important crop world-wide but to maintain its status, a method of somatic embryogenesis to produce clonal populations is required. Despite recent improvements in callus production the formation of somatic embryos and plantlet regeneration remain problematic. This thesis identified lauric acid accumulation as a potential marker for coconut seedling development and used it as a nutrient in combination with other culture conditions to promote embryogenesis or germination. It was found that lauric acid content was correlated with seedling development. The fatty acid together with naphthaleneacetic acid, 6-benzylaminopurine and 77Z}'o-inositol in the culture medium increased the growth of the organs (shoots, roots and haustorium) of seedlings mimicking, to some extent, the development of intact nuts. Metabolic studies showed that lauric acid is used as a precursor of other fatty acids and complex lipids and that their contents varied with the organ and the developmental stage of the seedling. In somatic embryogenesis, lauric acid combined with ABA promoted callus differentiation and formation of proembryos. Studies of 2,4-D metabolism revealed that deciding upon the optimum concentration of the auxin to use in coconut somatic embryogenesis is complicated by its rate of metabolism and conditions of culture (sucrose and 2,4-D concentrations). Five classes of metabolites (glucose esters, peptide conjugates, basic metabolites, triacylglycerol analogues containing short-chain elongated forms of 2,4-D and triacylglycerol analogues containing long-chain elongated forms of 2,4-D) were formed in the explants and their proportions varied according to the growth of the cultured tissue. The presence of non-polar metabolites was associated with de-differentiation of cxplants. Finally an improved protocol for somatic embryogenesis is suggested but many details remain to be improved.Open Acces