Relative production rates of 6^{6}He, 9^{9}Be, 12^{12}C in astrophysical environments

We assume an environment of neutrons and $\alpha$-particles of given density and temperature where nuclear syntheses into $^{6}$He, $^{9}$Be and $^{12}$C are possible. We investigate the resulting relative abundance as a function of density and temperature. When the relative abundance of $\alpha$-particles $Y_{\alpha}$ is between 0.2 and 0.9, or larger than 0.9, the largest production is $^{9}$Be or $^{12}$C, respectively. When $Y_{\alpha}<0.2$ $^{6}$He is mostly frequently produced for temperatures above about 2 GK whereas the $^{9}$Be production dominates at smaller temperatures.Comment: 5 pages, 4 figure

Few-body decay and recombination in nuclear astrophysics

Three-body continuum problems are investigated for light nuclei of astrophysical relevance. We focus on three-body decays of resonances or recombination via resonances or the continuum background. The concepts of widths, decay mechanisms and dynamic evolution are discussed. We also discuss results for the triple $\alpha$ decay in connection with $2^+$ resonances and density and temperature dependence rates of recombination into light nuclei from $\alpha$-particles and neutrons.Comment: 9 pages, 8 figures. Proceedings of the 21st European Few Body Conference held in Salamanca (Spain) in August-September 201

Direct and sequential radiative three-body reaction rates at low temperatures

We investigate the low-temperature reaction rates for radiative capture processes of three particles. We compare direct and sequential capture mechanisms and rates using realistic phenomenological parametrizations of the corresponding photodissociation cross sections.Energy conservation prohibits sequential capture for energies smaller than that of the intermediate two-body structure. A finite width or a finite temperature allows this capture mechanism. We study generic effects of positions and widths of two- and three-body resonances for very low temperatures. We focus on nuclear reactions relevant for astrophysics, and we illustrate with realistic estimates for the $\alpha$-$\alpha$-$\alpha$ and $\alpha$-$\alpha$-$n$ radiative capture processes. The direct capture mechanism leads to reaction rates which for temperatures smaller than 0.1 GK can be several orders of magnitude larger than those of the NACRE compilation.Comment: To be published in European Physical Journal

Cluster sum rules for three-body systems with angular-momentum dependent interactions

We derive general expressions for non-energy weighted and energy-weighted cluster sum rules for systems of three charged particles. The interferences between pairs of particles are found to play a substantial role. The energy-weighted sum rule is usually determined by the kinetic energy operator, but we demonstrate that it has similar additional contributions from the angular momentum and parity dependence of two- and three-body potentials frequently used in three-body calculations. The importance of the different contributions is illustrated with the dipole excitations in $^6$He. The results are compared with the available experimental data.Comment: 11 pages, 3 figures, 2 table

Parliamentary roll-call voting as a complex dynamical system:The case of Chile

A method is proposed to study the temporal variability of legislative roll-call votes in a parliament from the perspective of complex dynamical systems. We studied the Chilean Chamber of Deputies’ by analyzing the agreement ratio and the voting outcome of each vote over the last 19 years with a Recurrence Quantification Analysis and an entropy analysis (Sample Entropy). Two significant changes in the temporal variability were found: one in 2014, where the voting outcome became more recurrent and with less entropy, and another in 2018, where the agreement ratio became less recurrent and with higher entropy. These changes may be directly related to major changes in the Chilean electoral system and the composition of the Chamber of Deputies, given that these changes occurred just after the first parliamentary elections with non-compulsory voting (2013 elections) and the first elections with a proportional system in conjunction with an increase in the number of deputies (2017 elections) were held.</p

Fixation of bioactive compounds to the cuticle of Artemia

Artemia is extensively used in aquaculture to feed early stages of cultured marine species. A problem associated with this practice is that Artemia fails to supply some essential nutrients. As a possible solution, we have devised a procedure to make Artemia a vehicle for exogenous nutrients and other bioactive compounds. It consists of the construction of chimeric proteins composed of a chitin-binding domain, which binds to the cuticle of Artemia, and a carrier domain that conveys a functional property. As confirmatory examples, we describe the successful fixation to Artemia's metanauplii of two hybrid proteins: a β-galactosidase from the thermophilic bacterium Thermotoga maritima and the jellyfish green fluorescent protein (GFP), both linked to the CBM2 chitin-binding domain from the hyperthermophilic archaeon Pyrococcus furiosus. Positive results of experiments carried out ex vivo and in vivo show the validity of this approach. The methodology used could become a general procedure for the attachment of different kinds of bioactive compounds, such as enzymes, hormones, antibiotics, etc., to the cuticle of Artemia as well as other arthropods. Statement of relevance: Our results overcome shortcomings of Artemia as a feedstock.En prensa2,04

DIGESTIVE ENZYMES PROFILE IN OCTOPUS VULGARIS PARALARVAE FED WITH ARTEMIA ENRICHED WITH MARINE PHOSPHOLIPIDS

The common octopus (Octopus vulgaris) is an excellent candidate for aquaculture production, however the development of its culture needs to overcome the high paralarvae mortality which points out to zootechnical and nutritional problems. Enhancing the knowledge on paralarvae digestive physiology could increase the possibilities to optimize the diet in order to improve the paralarval growth and survival. In the present study, the effect of fed with Artemia enriched with marine phospholipids on digestive enzyme activity of octopus paralarvae from hatchling and 12 days old paralarvae have been studied

Preliminary Results on Light Conditions Manipulation in Octopus vulgaris (Cuvier, 1797) Paralarval Rearing

High paralarvae mortality is a major bottleneck currently hindering the control over the lifecycle of common octopus (Octopus vulgaris Cuvier, 1797). It is believed that this problem might be related to either zoo-technical and/or nutritional aspects. The present paper is focused on the study of different zoo-technical aspects related to light conditions on the rearing of paralarvae, including the effects of polarization in prey ingestion, the use of a blue filter to simulate natural conditions, and the use of focused light to avoid reflections of the rearing tank’s walls. In the first experiment, O. vulgaris paralarvae ingestion of Artemia sp. and copepods (Tisbe sp.) was assessed under either normal or polarized light. In the second experiment, the effect of a blue filter with natural light or focused artificial light on growth and mortality was assessed over 15 days of rearing. Ingestion rate was not influenced by light polarization. Nonetheless, a significantly higher ingestion of Artemia sp. with respect to copepods was observed. The blue filter promoted the use of natural light conditions in Octopus paralarval culture, while focused light reduced the collision of the paralarvae against the walls. However, no significant differences were found in paralarval growth nor survivalEn prens