Quasinormal modes of a black hole with a cloud of strings in Einstein-Gauss-Bonnet gravity

The quasinormal modes for a scalar field in the background spacetime corresponding to a black hole, with a cloud of strings, in Einstein-Gauss-Bonnet gravity, and the tensor quasinormal modes corresponding to perturbations in such spacetime, were both calculated using the WKB approximation. In the obtained results we emphasize the role played by the parameter associated with the string cloud, comparing them with the results already obtained for the Boulware-Deser metric. We also study how the Gauss-Bonnet correction to general relativity affects the results for the quasinormal modes, comparing them with the same background in general relativity.Comment: 15 pages, 7 figures; To appear in IJMP

Cloud of strings in f(R) gravity

We derive the solution for a spherically symmetric string cloud configuration in a d-dimensional spacetime in the framework of f(R) theories of gravity. We also analyze some thermodynamic properties of the joint black hole - cloud of strings solution. For its Hawking temperature, we found that the dependence of the mass with the horizon is significantly different in both theories. For the interaction of a black hole with thermal radiation, we found that the shapes of the curves are similar, but shifted. Our analysis generalizes some known results in the literature.Comment: Version accepted for CP

Helminth parasites of Madeiran rockpool fishes, with a redescription of Schikhobalotrema longivesiculatum Orecchia & Paggi, 1975 (Digenea: Haplosplanchnidae), and some comments on their zoogeographical relationships

Seven species of Madeiran rockpool fishes were examined for their helminth parasites. Only two of these harboured helminth parasites. The most frequently encountered parasite was the digenean Schikhobalotrema longivesiculatum Orecchia & Paggi, 1975 from Parablennius parvicornis; this species is redescribed and discussed. The paucity of the parasite fauna of Madeiran rockpool fishes and the zoogeographical relationships of the digenean fauna of Madeiran marine fishes are commented upon.info:eu-repo/semantics/publishedVersio

The implementation of mobile location based-games and Qr codes : the case of MobiGeo

Education is being revolutionized by the introduction, of mobile technologies in the teaching and learning process. However, studies that focus in the application of mobile technologies to informal learning environments is scarce and not systematized [1]. This is the reason for conducting a research project that involved a urban game MobiGeo, designed in to take better advantage of the flexibility and ubiquity offered by the Mobile Learning (ML) but also taking into account the importance of motivation and interaction to enhance students learning. The definition of ML has been a complicated task for researchers, but there are assumptions that can not be neglected: the mobility, portability and ubiquity [2], these are features that will drive new learning spaces and thus motivate students. This idea is supported by [2] that introduces the concepts of "just in time", "just enough" and "just-for-me" and [4] that speaks of the triad "location independence”, "independence time" and "meaningful content”. These principles of "anytime" and "anywhere" consolidated by mobile technologies came to renew the variety of educational activities available to teachers and in this context arises the concept of mobile location-based games. According to [5] "these games are played in physical space, but at the same time, they are supported by actions and events in an interconnected virtual space", which can be classified into three categories: ludic, pedagogic and hybrid. By being in direct contact with the contents to assimilate and move in a real context, students will have a more significant learning [6] and this will result in the mobilization of knowledge in different contexts. To make the connection between the physical and the virtual world, our research has made use of Qr codes as these devices provide information in real time and in a dynamically way. For this research was idealized an urban game called “MobiGeo”, that respect the principles suggested by [7] and that has as common thread the history of the European Union. To measure results the researchers developed a questionnaire that was adapted from a proposal of [8] which created a "Model to evaluate Educational Games”, so our proposal was built taking into account the motivational model of Kirkpatrick (level1) and encompassing three major dimensions: Motivation/Interest, Interaction and Perceived Learning. To assess the Motivation/Interest was used the Model ARCS (Relevance, Confidence and Satisfaction) and items of Fun, Immersion and Challenge of “Game User Experience”. On the other hand the interaction was evaluated by items of the Social Interaction dimension of the “Game of User Experience”, the Learning Perceptions were evaluated by Bloom's Taxonomy (Knowledge category). In this paper we present the design and implementation of the MobiGeo outdoor learning activity with a group of 173 students from the 7th grade of a basic school in the north of Portugal. Initial results show that this urban game with Qr codes was an adequate activity to use in informal learning environments that could engage students in gaming with high degrees of motivation and interaction in order to solve the tasks presented to them and so consolidate and acquired new knowledge about the European Union.CIEC – Research Centre on Child Studies, UM (FCT R&D 317

Tsallis holographic dark energy in the Brans-Dicke cosmology

Using the Tsallis generalized entropy, holographic hypothesis and also considering the Hubble horizon as the IR cutoff, we build a holographic model for dark energy and study its cosmological consequences in the Brans-Dicke framework. At first, we focus on a non-interacting universe, and thereinafter, we study the results of considering a sign-changeable interaction between the dark sectors of the cosmos. Our investigations show that, compared with the flat case, the power and freedom of the model in describing the cosmic evolution is significantly increased in the presence of the curvature. The stability analysis also indicates that, independent of the universe curvature, both the interacting and non-interacting cases are classically unstable. In fact, both the classical stability criterion and an acceptable behavior for the cosmos quantities, including the deceleration and density parameters as well as the equation of state, are not simultaneously obtainable.Comment: Accepted version, Eur. Phys. J. C (2018