Nonassociative structures and 3-Sasakian homogeneous manifolds

The 3-Sasakian homogeneous spaces are certain contact manifolds whose geometric structure is very well codified in Lie theoretical terms. This fact can be used to find interesting invariant affine connections, with nice properties or special holonomies. The more fruitful results arise in the particular case of the 7-dimensional 3-Sasakian homogeneous manifolds, that is, the corresponding sphere and the Aloff-Wallach space, although the target is to find a good connection independently of the dimension. A nonassociative structure related to Lie algebras appears through this study, that one of symplectic triple system. In particular the curvature of an affine connection can be written by means of the binary and ternary products in this triple system. Also, for some distinguished connections, the holonomy algebra can be described in a unified form, what helps to find a suitable candidate for a best affine connection adapted to the geometry of the 3-Sasakian manifold, which necessarily will have nonzero torsion.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Spatiotemporal Variations in Abundance and Biomass of Planktonic Ciliates Related to Environmental Variables in a Temporal Pond, Argentina

This report describes the structure and seasonal dynamics of ciliated protozoa associated with variations in the physicochemical characteristics of the environment in a temporary pond in the Buenos Aires province, Argentina. Plankton samples were obtained and physicochemical variables measured monthly for two years. A total of 50 planktonic ciliates were recorded. The highest species richness occurred during the pond´s filling and stable-hydric phases. Upon the pond´s desiccation, the number of ciliate species decreased, with the lowest values being recorded in spring; while the highest abundance and biomass were observed before the droughts. Ciliate diversity tended to be higher after droughts but decreased with pond desiccation. Most of the ciliate species were rare and found during the filling periods. Vorticella convallaria, Pelagostrobilidium wilberti, and Coleps hirtus were dominant; Cyclidium glaucoma, Strobilidium caudatum, Pseudochilodonopsis piscatoris, Limnostrombidium viride, L. pelagicum, and Chilodonella sp. were common; and Pelagostrombidium mirabile along with Rhabdostyla sp.?an epibiont on cladocerans?were occasional. The first and the sum of all axes in canonical correspondence analysis explained a significant portion of the ciliate-data variance. The autumn and winter samples grouped together corresponding to the highest conductivities, high precipitations, and low temperatures?properties characterizing the filling and stable-hydric periods. The species were distributed mainly according to conductivity and temperature gradients along the first canonical axis. The structure and temporal dynamics of planktonic ciliates from this temporary pond varied with the changes in physicochemical characteristics of the environment determined by flooding and desiccation.Fil: Kuppers, Gabriela Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Claps, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

Timelike geodesics around a charged spherically symmetric dilaton black hole

In this paper we study the timelike geodesics around a spherically symmetric charged dilaton black hole. The trajectories around the black hole are classified using the effective potential of a free test particle. This qualitative approach enables us to determine the type of the orbit described by the test particle without solving the equations of motion, if the parameters of the black hole and the particle are known. The connections between these parameters and the type of orbit described by the particle are obtained. To visualize the orbits we solve numerically the equation of motions for different values of the parameters envolved in our analysis. The effective potential of a free test particle looks different for a non-extremal and an extremal black hole, therefore we have examined separately these two types of black holes.Comment: 10 pages, 16 figure

EMI WN V. 3.0.0

The EMI Worker Nod

Stable maps and stable quotients

We analyze the relationship between two compactifications of the moduli space of maps from curves to a Grassmannian: the Kontsevich moduli space of stable maps and the Marian--Oprea--Pandharipande moduli space of stable quotients. We construct a moduli space which dominates both the moduli space of stable maps to a Grassmannian and the moduli space of stable quotients, and equip our moduli space with a virtual fundamental class. We relate the virtual fundamental classes of all three moduli spaces using the virtual push-forward formula. This gives a new proof of a theorem of Marian-Oprea-Pandharipande: that enumerative invariants defined as intersection numbers in the stable quotient moduli space coincide with Gromov--Witten invariants.Comment: 29 page

A Clifford algebra associated to generalized Fibonacci quaternions

In this paper we find a Clifford algebra associated to generalized Fibonacci quaternions. In this way, we provide a nice algorithm to obtain a division quaternion algebra starting from a quaternion non-division algebra and vice-versa