On Schwarzschild's Topology in Brane-Worlds

The topological structure of Schwarzschild's space-time and its maximal analytic extension are investigated in context of brane-worlds. Using the embedding coordinates, these geometries are seen as different states of the evolution of a single brane-world. Comparing the topologies and the embeddings it is shown that this evolution must be followed by a signature change in the bulk.Comment: 6 page

Investigating how educational technologies can enhance learning experiences by assisting different learning activities

Current educational technology implementations are done independently and not necessarily linked, neither with key elements of the pedagogic model, nor accommodating different learning styles. This work focuses on developing a framework that would standardise the use of assistive technologies in education. In particular, the focus of this work is on how social media, computer-assisted assessment, augmented and mixed reality can be used to improve the learning experience in certain educational contexts. This research study is based on a combination of grounded theory that included a literature review on the following relevant areas, covering key topics that correspond to the dimensions of the proposed framework: i) communication in education; ii) assessment; iii) and feedback. This stage provided a review of the learning activity spectrum that can be affected by educational technologies. The deliverable of this stage was a detailed literature review with distinct links to the action research in the form of specific pilot studies. The following stage provides a discussion on the impact of educational technologies on learning activities. The main deliverable is a review of current technologies with emphasis on how they affect specific learning activities The research also included an element of action research in the form of six pilot studies: i) Google Glass: Student Experience; ii) Google Glass: Presentation Feedback; iii) Google Glass: Feedback on Feedback; iv) Google Glass: Voting System; v) Social Media: Facebook/Twitter/LinkedIn; vi) Student Observable Behaviour. The pilots were conducted and analysed in order to provide sufficient evidence supporting the proposed framework guidelines. The framework proposed consists of four dimensions: i) content; ii) communication; iii) assessment; iv) feedback. This framework is a framework of good practice. It can be used to support academics who wishes to deploy educational technologies in support of a range of learning activities. Furthermore, the framework has the flexibility of applying different educational technologies for different scenarios without missing a standardised evaluation criteria

Dynamical aspects of Kinouchi-Copelli model: emergence of avalanches at criticality

We analyze the behavior of bursts of neural activity in the Kinouchi-Copelli model, originally conceived to explain information processing issues in sensory systems. We show that, at a critical condition, power-law behavior emerges for the size and duration of the bursts (avalanches), with exponents experimentally observed in real biological systems.Comment: Paper accepted for Brazilian Conference on Dynamics, Control and Applications (oral presentation and poster). 4 pages, 5 figure

Duality and interval analysis over idempotent semirings

In this paper semirings with an idempotent addition are considered. These algebraic structures are endowed with a partial order. This allows to consider residuated maps to solve systems of inequalities $A \otimes X \preceq B$. The purpose of this paper is to consider a dual product, denoted $\odot$, and the dual residuation of matrices, in order to solve the following inequality $A \otimes X \preceq X \preceq B \odot X$. Sufficient conditions ensuring the existence of a non-linear projector in the solution set are proposed. The results are extended to semirings of intervals

Experimental feeding of Sergentomyia minuta on reptiles and mammals: comparison with Phlebotomus papatasi

Background: Sergentomyiaminuta (Diptera: Phlebotominae) is an abundant sand fly species in the Mediterranean basin and a proven vector of reptile parasite Leishmania (Sauroleishmania) tarentolae. Although it feeds preferentially on reptiles, blood meal analyses and detection of Leishmania (Leishmania) infantum DNA in wild-caught S.minuta suggest that occasional feeding may occur on mammals, including humans. Therefore, it is currently suspected as a potential vector of human pathogens. Methods: A recently established S.minuta colony was allowed to feed on three reptile species (i.e. lizard Podarcissiculus and geckos Tarentolamauritanica and Hemidactylusturcicus) and three mammal species (i.e. mouse, rabbit and human). Sand fly mortality and fecundity were studied in blood-fed females, and the results were compared with Phlebotomuspapatasi, vector of Leishmania (L.) major. Blood meal volumes were measured by haemoglobinometry. Results: Sergentomyiaminuta fed readily on three reptile species tested, neglected the mouse and the rabbit but took a blood meal on human. However, the percentage of females engorged on human volunteer was low in cage (3%) and feeding on human blood resulted in extended defecation times, higher post-feeding mortality and lower fecundity. The average volumes of blood ingested by females fed on human and gecko were 0.97 µl and 1.02 µl, respectively. Phlebotomuspapatasi females readily fed on mouse, rabbit and human volunteer; a lower percentage of females (23%) took blood meal on the T.mauritanica gecko; reptilian blood increased mortality post-feeding but did not affect P.papatasi fecundity. Conclusions: Anthropophilic behaviour of S.minuta was experimentally demonstrated; although sand fly females prefer reptiles as hosts, they were attracted to the human volunteer and took a relatively high volume of blood. Their feeding times were longer than in sand fly species regularly feeding on mammals and their physiological parameters suggest that S.minuta is not adapted well for digestion of mammalian blood. Nevertheless, the ability to bite humans highlights the necessity of further studies on S.minuta vector competence to elucidate its potential role in circulation of Leishmania and phleboviruses pathogenic to humans. Graphical abstract: [Figure not available: see fulltext.].publishersversionpublishe