The seed of magnetic monopoles in the early inflationary universe from a 5D vacuum state

Starting from a 5D Riemann flat metric, we have induced an effective 4D Hermitian metric which has an antisymmetric part which is purely imaginary. We have worked an example in which both, non-metricity and cotorsion are zero. We obtained that the production of monopoles should be insignificant at the end of inflation and the tensor metric should come asymptotically diagonal and describing a nearly 4D de Sitter expansion.     

OxDNA to Study Species Interactions

Molecular ecology uses molecular genetic data to answer traditional ecological questions in biogeography and biodiversity, among others. Several ecological principles, such as the niche hypothesis and the competitive exclusions, are based on the fact that species compete for resources. More in generally, it is now recognized that species interactions play a crucial role in determining the coexistence and abundance of species. However, experimentally controllable platforms, which allow us to study and measure competitions among species, are rare and difficult to implement. In this work, we suggest exploiting a Molecular Dynamics coarse-grained model to study interactions among single strands of DNA, representing individuals of different species, which compete for binding to other oligomers considered as resources. In particular, the well-established knowledge of DNA–DNA interactions at the nanoscale allows us to test the hypothesis that the maximum consecutive overlap between pairs of oligomers measure the species’ competitive advantages. However, we suggest that a more complex structure also plays a role in the ability of the species to successfully bind to the target resource oligomer. We complement the simulations with experiments on populations of DNA strands which qualitatively confirm our hypotheses. These tools constitute a promising starting point for further developments concerning the study of controlled, DNA-based, artificial ecosystems.     

Quintessential inflation from a variable cosmological constant in a 5D vacuum

We explore an effective 4D cosmological model for the universe where the variable cosmological constant governs its evolution and the pressure remains negative along all the expansion. This model is introduced from a 5D vacuum state where the (space-like) extra coordinate is considered as noncompact. The expansion is produced by the inflaton field, which is considered as nonminimally coupled to gravity. We conclude from experimental data that the coupling of the inflaton with gravity should be weak, but variable in different epochs of the evolution of the universe.     

The bang of a white hole in the early universe from a 6D vacuum state: origin of astrophysical spectrum

Using a previously introduced model in which the expansion of the universe is driven by a single scalar field subject to gravitational attraction induced by a white hole during the expansion (from a 6D vacuum state), we study the origin of squared inflaton fluctuations spectrum on astrophysical scales.     

Break up of spectator residues at ultra-relativistic energies

The 200GeV/u sulfur beam available at CERN was used to bombard a 1.5 mg/cm Au target. Light nuclei were detected at 60° in the laboratory using a silicon telescope. The shape of the inclusive atomic number distribution of intermediate mass fragments with an atomic numberZ ≥ 2 looks different from the one measured on theO +Au system at the same bombarding energy.     

Synthesis and thermal transformations of zinc-substituted magnetites

In the present study, zinc-substituted magnetites of the Fe_3???X Zn _X O₄ type were prepared by co-precipitation in the range 0 ≤?X?≤ 1 and, further, annealed in free atmosphere, at 800° for 3 h. The samples were characterized by X-ray diffraction and Mössbauer spectroscopy. The results showed that the annealed samples were oxidized and converted into Fe₂O₃ and ZnFe₂O₄, in relative amounts that varied with X.     

Meson photoproduction on the nucleon with polarized photons

Meson photoproduction with polarized photons has proved to be a powerful tool to identify contributions of baryon resonances that are not evident in the differential cross-sections. It provides information that are complementary to those extracted using pion-nucleon scattering data. Extensive results have been produced in the past on beam asymmetries by the Graal collaboration for η and π ⁰ on the proton. New results are now available for the same reactions on the quasi-free neutron and for the K⁺ photoproduction on the proton. Contributions from hitherto undetected baryon resonances may be important to understand the results.     

Structural, magnetic and hyperfine characterization of zinc-substituted magnetites

Nanosized Fe_3???x Zn _x O₄ powders were synthesized by co-precipitation and characterized by total chemical analysis, X-ray diffraction, magnetic susceptibility and Mössbauer spectroscopy. The results showed that, for x?≤?0.15, the as-prepared samples are mostly zinc-substituted magnetites but have maghemite as a minor phase. For x?≥?0.30, only the Fe_3???x Zn _x O₄ solid solution is found. Increasing the zinc content from the end concentration x?=?0, increases the lattice parameter but smaller become the mean crystalline diameter and the magnetic susceptibility. In addition, the magnetic hyperfine fields of the iron sites in the spinel structure, A and B, decrease up to collapse at x?≤?0.90.