Ising Field Theory on a Pseudosphere

We show how the symmetries of the Ising field theory on a pseudosphere can be exploited to derive the form factors of the spin fields as well as the non-linear differential equations satisfied by the corresponding two-point correlation functions. The latter are studied in detail and, in particular, we present a solution to the so-called connection problem relating two of the singular points of the associated Painleve VI equation. A brief discussion of the thermodynamic properties is also presented.Comment: 39 pages, 6 eps figures, uses harvma

A development approach to industrial robots programming

This paper proposes a development approach to industrial robot programming, that includes: a truly high level and declarative language; an easy-to-use frontend; an intermediate representation; an automatic generator of the robot code generators. So, we introduce a new paradigm to program industrial robots, that focus on the modeling of the system, rather than on the robot. It will improve the programming and maintenance tasks, allowing the reuse of source code, because this source code will be machine independent

Uma proposta de linguagem de programação para robótica

Este artigo destina-se a apresentar alguns problemas existentes nas linguagens de programacão de robôs, e uma possível solucão dos mesmos através da utilização da linguagem Reativa Síncrona RS. Uma implementacão prática será apresentada a fim de mostrar como o uso desta linguagem pode facilitar o desenvolvimento de programas para os robôs, neste caso, industriais. Entretanto, verifica-se a necessidade da existência de um módulo intermediário responsável por traduzir uma linguagem declarativa para código final de diferentes robôs, a fim de garantir a portabilidade de código.This paper presents some existing problems in robotics programming languages and a possible solution using a reactive and synchronous language called RS. An implementation will show how the RS language can facilitate the robot´s programming, in this case, industrial robots. However, it should be necessary to create an intermediate module responsible for translating a declarative language to assembly code, in different robots, granting code portability

A graphical interface based on grafcet for programming industrial robots off-line

This paper presents the current development stage of our approach to industrial robot programming, that is the graphical interface for our environment, that is based on the well-known Grafcet. Our approach focus on the modelling of the system, rather than on the robot. So, it will improve the programming and maintenance tasks, allowing the reuse of source code.Fundação para a Ciência e a Tecnologia (FCT

Uso da linguagem RS em robótica

Este artigo destina-se a apresentar a linguagem Reativa Síncrona RS como ferramenta para o desenvolvimento de software para robótica, tanto industrial como móvel, criando um mais alto nível de abstração no desenvolvimento de programas. A linguagem RS tem características que facilitam bastante o desenvolvimento e manutenção de programas deste tipo, visto que é uma linguagem reactiva, simples, paralela e distribuída, e de tempo real, características estas que são importantes para o desenvolvimento deste tipo de programas

Validation of percutaneous puncture trajectory during renal access using 4D ultrasound reconstruction

"Progress in Biomedical Optics and Imaging, vol. 16, nr. 43"Background: An accurate percutaneous puncture is essential for disintegration and removal of renal stones. Although this procedure has proven to be safe, some organs surrounding the renal target might be accidentally perforated. This work describes a new intraoperative framework where tracked surgical tools are superimposed within 4D ultrasound imaging for security assessment of the percutaneous puncture trajectory (PPT). Methods: A PPT is first generated from the skin puncture site towards an anatomical target, using the information retrieved by electromagnetic motion tracking sensors coupled to surgical tools. Then, 2D ultrasound images acquired with a tracked probe are used to reconstruct a 4D ultrasound around the PPT under GPU processing. Volume hole-filling was performed in different processing time intervals by a tri-linear interpolation method. At spaced time intervals, the volume of the anatomical structures was segmented to ascertain if any vital structure is in between PPT and might compromise the surgical success. To enhance the volume visualization of the reconstructed structures, different render transfer functions were used. Results: Real-time US volume reconstruction and rendering with more than 25 frames/s was only possible when rendering only three orthogonal slice views. When using the whole reconstructed volume one achieved 8-15 frames/s. 3 frames/s were reached when one introduce the segmentation and detection if some structure intersected the PPT. Conclusions: The proposed framework creates a virtual and intuitive platform that can be used to identify and validate a PPT to safely and accurately perform the puncture in percutaneous nephrolithotomy.The authors acknowledge to Foundation for Science and Technology (FCT) - Portugal for the fellowships with references: SFRH/BD/74276/2010.info:eu-repo/semantics/publishedVersio

Thoracic wall reconstruction using ultrasound images to model/bend the thoracic prosthesis for correction of pectus excavatum

Pectus excavatum is the most common congenital deformity of the anterior thoracic wall. The surgical correction of such deformity, using Nuss procedure, consists in the placement of a personalized convex prosthesis into sub-sternal position to correct the deformity. The aim of this work is the CT-scan substitution by ultrasound imaging for the pre-operative diagnosis and pre-modeling of the prosthesis, in order to avoid patient radiation exposure. To accomplish this, ultrasound images are acquired along an axial plane, followed by a rigid registration method to obtain the spatial transformation between subsequent images. These images are overlapped to reconstruct an axial plane equivalent to a CT-slice. A phantom was used to conduct preliminary experiments and the achieved results were compared with the corresponding CT-data, showing that the proposed methodology can be capable to create a valid approximation of the anterior thoracic wall, which can be used to model/bend the prosthesis.Fundação para a Ciencia e Tecnologia (FCT