Kinematics of a Spacetime with an Infinite Cosmological Constant

A solution of the sourceless Einstein's equation with an infinite value for the cosmological constant \Lambda is discussed by using Inonu-Wigner contractions of the de Sitter groups and spaces. When \Lambda --> infinity, spacetime becomes a four-dimensional cone, dual to Minkowski space by a spacetime inversion. This inversion relates the four-cone vertex to the infinity of Minkowski space, and the four-cone infinity to the Minkowski light-cone. The non-relativistic limit c --> infinity is further considered, the kinematical group in this case being a modified Galilei group in which the space and time translations are replaced by the non-relativistic limits of the corresponding proper conformal transformations. This group presents the same abstract Lie algebra as the Galilei group and can be named the conformal Galilei group. The results may be of interest to the early Universe Cosmology.Comment: RevTex, 7 pages, no figures. Presentation changes, including a new Title. Version to appear in Found. Phys. Let

Semi-parametric models: an application in medicine

Conferência realizada em Rhodes, Grécia, de 23-28 de setembro de 2019.Modeling of medical data often requires the inclusion of non-linear forms of the predictors and, the Generalized Additive Models (GAMs) can provide an excellent fit in the presence of non-linear relationships and significant noise in the predictor variables. The accurate assessment of QT interval is of paramount importance since its prolongation (LQTS) is a life threatening condition. The QT interval is affected by heart rate and gender and may be adjusted to improve the detection of patients at increased risk. Bazett's formula is the most commonly used QT correction formula, and takes into account only the heart rate assessed by the RR interval, and cut-of values of corrected QT are defined according to gender. In this work we analyzed relevance of QRS, together with gender and RR to explain QT length using GAMs. Results showed that QRS and gender are significant to non-pathological QT modelling.info:eu-repo/semantics/publishedVersio

Resonant tunneling through protected quantum dots at phosphorene edges

We theoretically investigate phosphorene zigzag nanorribons as a platform for constriction engineering. In the presence of a constriction at the upper edge, quantum confinement of edge protected states reveals resonant tunnelling Breit-Wigner transmission peaks, if the upper edge is uncoupled to the lower edge. Coupling between edges in thin constrictions gives rise to Fano-like and anti-resonances in the transmission spectrum of the system.Comment: 8 pages,7 figure

Process analysis using business process management: a case study on incident management

Business process management is widely used to improve companies’ competitive level. Incident management is a critical process as it supports the main services of an organization. Its speed and accuracy are paramount to companies. This research aims at analysing an incident management process of a global company and produce managerial recommendations on how to improve its performance. A case study approach is conducted. Process analysis is conducted based in interviews, direct observation, and focus group to assure data triangulation. Process improvement is based on the goals of the process and managerial recommendations are provided to support that improvement.info:eu-repo/semantics/acceptedVersio