Long-range interacting many-body systems with alkaline-earth-metal atoms

Alkaline-earth-metal atoms exhibit long-range dipolar interactions, which are generated via the coherent exchange of photons on the 3P_0-3D_1-transition of the triplet manifold. In case of bosonic strontium, which we discuss here, this transition has a wavelength of 2.7 \mu m and a dipole moment of 2.46 Debye, and there exists a magic wavelength permitting the creation of optical lattices that are identical for the states 3P_0 and 3D_1. This interaction enables the realization and study of mixtures of hard-core lattice bosons featuring long-range hopping, with tuneable disorder and anisotropy. We derive the many-body Master equation, investigate the dynamics of excitation transport and analyze spectroscopic signatures stemming from coherent long-range interactions and collective dissipation. Our results show that lattice gases of alkaline-earth-metal atoms permit the creation of long-lived collective atomic states and constitute a simple and versatile platform for the exploration of many-body systems with long-range interactions. As such, they represent an alternative to current related efforts employing Rydberg gases, atoms with large magnetic moment, or polar molecules

HOMOGENEOUS RIEMANNIAN MANIFOLDS WITH NON-TRIVIAL NULLITY

We develop a general theory for irreducible homogeneous spaces M = G/H, in relation to the nullity distribution ν of their curvature tensor. We construct natural invariant (different and increasing) distributions associated with the nullity, that give a deep insight of such spaces. In particular, there must exist an order-two transvection, not in the nullity, with null Jacobi operator. This fact was very important for finding out the first homogeneous examples with non-trivial nullity, i.e., where the nullity distribution is not parallel. Moreover, we construct irreducible examples of conullity k = 3, the smallest possible, in any dimension. None of our examples admit a quotient of finite volume. We also proved that H is trivial and G is solvable if k = 3. Another of our main results is that the leaves, i.e., the integral manifolds, of the nullity are closed (we used a rather delicate argument). This implies that M is a Euclidean affine bundle over the quotient by the leaves of ν. Moreover, we prove that ν⊥ defines a metric connection on this bundle with transitive holonomy or, equivalently, ν⊥ is completely non-integrable (this is not in general true for an arbitrary autoparallel and at invariant distribution). We also found some general obstruction for the existence of non-trivial nullity: e.g., if G is reductive (in particular, if M is compact), or if G is two-step nilpotent

Evaluación educativa de la implementación de un programa interactivo para la adquisición de conocimientos medioambientales

Para conocer la calidad docente dentro de nuevas metodologías de aprendizaje es importante prestar especial atención a la evaluación, sus pautas, los diseños realizados y el proceso en sí, que junto con los resultados obtenidos nos indican los criterios susceptibles de mejora, así como las áreas fuertes y débiles a considerar para futuras experiencias dentro de la docencia. La evaluación se ha realizado dentro del proyecto“Propuesta metodológica para el aprendizaje autónomo de conceptos medioambientales en la formación de maestros”, que nace con la intención de adecuar la metodología de la asignatura obligatoria Fundamentos científicos medioambientales, por su adaptación en su manera de desarrollo a través de entornos virtuales

The effects of business associations in the export–survival relationship: An application to the DOC Rioja wine industry

Much has been said about the role that business associations play in the survival of firms, but little is known about how this influences the relationship between exports and the survival of firms. Considering the diverging theoretical assumptions about the importance of business associations, we hypothesize in this paper on the direct effect of association membership on the survival of firms, and its moderating effect on the export–survival relationship. For Qualified Designation of Origin (DOC) Rioja wineries, we show that both exporting and association membership have a positive effect on the survival of firms, although association membership reduces the positive effect of exports to survive. These results hold up under alternative survival model specifications. The study explores the complex role of associations in the wine industry, which is important to understand in the context of the current COVID-19 crisis

Determinants of organic wine production: an application in the DOC Rioja wine industry

Aim of study: To analyse the role that valuable resources and agglomeration would play in the decision to produce organic wines. Area of study: The Controlled Designation of Origin (DOC) Rioja wine industry in Spain, the leading qualified denomination of origin of Spain. Material and methods: Taking into account the nature of the dependent variable, a binomial logit model was used. Main results: This paper confirms the significance of valuable resources such as financial resources and human resources, but also of knowledge-based spillovers from proximate organic wineries in improving the probability of producing organic wines. Contrary to expectations, technological resources and experience in the wine industry have no significant effect. Research highlights: The resource based-view and the cluster approach are complementary to improving the predictive elements of producing organic wine in the DOC Rioja wine industry. The authors were unable to pre-register the analysis involving primary data collection before the data collection exercise starts. This requirement is from January 2022 and the survey period of this paper was on 2017. According to the editorial policy of the journal this analysis should be considered exploratory