Permanent vascular access in patients with end-stage renal disease, Brazil

OBJECTIVE: To assess factors associated with the establishment of permanent vascular access for patients with end-stage renal disease. METHODS: Cross-sectional study conducted in a nationally representative sample of Brazilian end-stage renal disease patients in dialysis and transplant centers during 2007. The sample comprised only patients who received hemodialysis as a primary therapy modality and reported the type of vascular access for their primary hemodialysis treatment (N=2,276). Data were from the TRS Project - "Economic and Epidemiologic Evaluation of Modalities of Renal Replacement Therapy in Brazil". Multiple logistic regression analysis was used to assess factors associated with the establishment of permanent vascular access in these patients. RESULTS: About 30% of the patients studied had an arteriovenous vascular access. The following factors were associated with a lower likelihood of having an arteriovenous vascular access as a primary type of access: time of hemodialysis start since the diagnosis of chronic renal failure < 1 year; shorter dialysis therapy; having no private health insurance; living in the central-western, northeastern and southeastern regions of Brazil; and living in the northern region plus having no private health insurance. In the final model there was found a positive association between the outcome and pre-dialysis care and no were association with socioeconomic and comorbidity variables. CONCLUSIONS: The study results showed that the focus should on pre-dialysis care to increase the establishment of an arteriovenous vascular access before starting hemodialysis in Brazil.

Instrumentação e monitorização na avaliação do comportamento de maciços e estruturas envolventes: caso de poços em meio urbano

Atualmente, a escavação de poços em locais densamente ocupados requer medidas severas para reduzir riscos e possíveis influências quer na própria obra quer em estruturas próximas. Neste campo, a instrumentação geotécnica e a sua monitorização tem um papel determinante na execução de obras geotécnicas, sendo que neste trabalho é dado um especial realce à instrumentação utilizada, às atividades de observação geotécnica, bem como à análise e interpretação das leituras para o controlo de movimentos induzidos no terreno pelas escavações. Este acompanhamento é baseado num plano de instrumentação, sendo descrito de uma forma transversal a importância do projeto e em particular das fases do processo de investigação geotécnica. O acompanhamento da execução dos poços para a futura Estação da Reboleira, permitiu validar as soluções de projeto para um determinado método construtivo, determinadas através de métodos numéricos e semi-empíricos, e abordados neste trabalho. A monitorização sistemática desde o início das escavações até ao revestimento secundário, permitiu tecer apreciações sobre os valores obtidos, apresentando-se alguns registos. Todas estas ações visam controlar e antecipar riscos de acidentes provocados pela execução de escavações, pelo que nesta tese é também realçada a importância da segurança e higiene no trabalho na prevenção dos riscos profissionais, independentemente da sua origem.

BITalino: a novel hardware framework for physiological computing

Physical computing has spun a true global revolution in the way in which the digital interfaces with the real world. From bicycle jackets with turn signal lights to twitter-controlled christmas trees, the Do-it-Yourself (DiY) hardware movement has been driving endless innovations and stimulating an age of creative engineering. This ongoing (r)evolution has been led by popular electronics platforms such as the Arduino, the Lilypad, or the Raspberry Pi, however, these are not designed taking into account the specific requirements of biosignal acquisition. To date, the physiological computing community has been severely lacking a parallel to that found in the DiY electronics realm, especially in what concerns suitable hardware frameworks. In this paper, we build on previous work developed within our group, focusing on an all-in-one, low-cost, and modular biosignal acquisition hardware platform, that makes it quicker and easier to build biomedical devices. We describe the main design considerations, experimental evaluation and circuit characterization results, together with the results from a usability study performed with volunteers from multiple target user groups, namely health sciences and electrical, biomedical, and computer engineering. Copyright © 2014 SCITEPRESS - Science and Technology Publications. All rights reserved.

Virtual laboratory for educational environments

In this paper a new simulation environment for a virtual laboratory to educational proposes is presented. The Logisim platform was adopted as the base digital simulation tool, since it has a modular implementation in Java. All the hardware devices used in the laboratory course was designed as components accessible by the simulation tool, and integrated as a library. Moreover, this new library allows the user to access an external interface. This work was motivated by the needed to achieve better learning times on co-design projects, based on hardware and software implementations, and to reduce the laboratory time, decreasing the operational costs of engineer teaching. Furthermore, the use of virtual laboratories in educational environments allows the students to perform functional tests, before they went to a real laboratory. Moreover, these functional tests allow to speed-up the learning when a problem based approach methodology is considered. © 2014 IEEE.

A sensor classification strategy for robotic manipulators

In practice the robotic manipulators present some degree of unwanted vibrations. The advent of lightweight arm manipulators, mainly in the aerospace industry, where weight is an important issue, leads to the problem of intense vibrations. On the other hand, robots interacting with the environment often generate impacts that propagate through the mechanical structure and produce also vibrations. In order to analyze these phenomena a robot signal acquisition system was developed. The manipulator motion produces vibrations, either from the structural modes or from endeffector impacts. The instrumentation system acquires signals from several sensors that capture the joint positions, mass accelerations, forces and moments, and electrical currents in the motors. Afterwards, an analysis package, running off-line, reads the data recorded by the acquisition system and extracts the signal characteristics. Due to the multiplicity of sensors, the data obtained can be redundant because the same type of information may be seen by two or more sensors. Because of the price of the sensors, this aspect can be considered in order to reduce the cost of the system. On the other hand, the placement of the sensors is an important issue in order to obtain the suitable signals of the vibration phenomenon. Moreover, the study of these issues can help in the design optimization of the acquisition system. In this line of thought a sensor classification scheme is presented. Several authors have addressed the subject of the sensor classification scheme. White (White, 1987) presents a flexible and comprehensive categorizing scheme that is useful for describing and comparing sensors. The author organizes the sensors according to several aspects: measurands, technological aspects, detection means, conversion phenomena, sensor materials and fields of application. Michahelles and Schiele (Michahelles & Schiele, 2003) systematize the use of sensor technology. They identified several dimensions of sensing that represent the sensing goals for physical interaction. A conceptual framework is introduced that allows categorizing existing sensors and evaluates their utility in various applications. This framework not only guides application designers for choosing meaningful sensor subsets, but also can inspire new systems and leads to the evaluation of existing applications. Today’s technology offers a wide variety of sensors. In order to use all the data from the diversity of sensors a framework of integration is needed. Sensor fusion, fuzzy logic, and neural networks are often mentioned when dealing with problem of combing information from several sensors to get a more general picture of a given situation. The study of data fusion has been receiving considerable attention (Esteban et al., 2005; Luo & Kay, 1990). A survey of the state of the art in sensor fusion for robotics can be found in (Hackett & Shah, 1990). Henderson and Shilcrat (Henderson & Shilcrat, 1984) introduced the concept of logic sensor that defines an abstract specification of the sensors to integrate in a multisensor system. The recent developments of micro electro mechanical sensors (MEMS) with unwired communication capabilities allow a sensor network with interesting capacity. This technology was applied in several applications (Arampatzis & Manesis, 2005), including robotics. Cheekiralla and Engels (Cheekiralla & Engels, 2005) propose a classification of the unwired sensor networks according to its functionalities and properties. This paper presents a development of a sensor classification scheme based on the frequency spectrum of the signals and on a statistical metrics. Bearing these ideas in mind, this paper is organized as follows. Section 2 describes briefly the robotic system enhanced with the instrumentation setup. Section 3 presents the experimental results. Finally, section 4 draws the main conclusions and points out future work.

Unbalance and field balacing virtual labs

One of the most common problems of rotating machinery is the rotor unbalance. The effects of rotor unbalance can vary from the malfunction of certain equipment to diseases related to the exposure to high vibration levels. However, the balancing procedure is known, it is mandatory to have qualified technicians to perform it. In this sense, the use of virtual balancing experiments is of great interest. The present demo is dedicated to present two different balancing simulators, which can be explored in conjunction, as they have complementary outputs. © 2014 IEEE.

Reshaping higher education systems in the MENA region: the contribution of remote and virtual labs

Learning is not only happening in school or university; it is also an important aspect of the daily life that allows students to remain in their biological and physical environment helping to reshape it, by applying what they have learnt. Today, the higher education sector is a part of important strategies used by countries in order to foster their development. Despite its geographical location, i.e. its closeness to Europe and Asia, the MENA (Middle East and North Africa) region still needs an integrated strategy for the advancement, reform, and update of its higher educational landscape. Although some solutions have been experimented in the region in the field of higher education, they have not been able to raise the quality of education to the level comparable that observed in developed countries. In other words, many MENA higher education systems are facing problems, for which solution ought to be sought. We analyse the situation of higher education systems in the MENA countries and the factors that affect the delay in achieving the level of education existing in other world regions, e.g. Europe, especially in the higher education sector. During the discussion, the impact of new technology-enhanced tools, such as remote laboratories, in the process of development and consolidation of MENA universities, is particularly stressed.

Design state exploration applied to the development of a remote lab for projectile launch experiments

This paper describes the application of Design State Exploration techniques in the development of a remote lab for projectile motion experiments. The application was enabled by the existence of two independent teams: one composed of a series of internships that started first and another with two grantees that started a few months later. The paper presents evidence on how this approach provided gains in the development process conducted by the second team that benefited from design state exploration studies performed by the first team. This particular aspect is highlighted in relation to the work already presented in the 10th Remote Engineering and Virtual Instrumentation (REV) conference.

Educational application of remote experimentation for mobile devices

In this article the authors describe the application development RExMobile and the importance of remote experimentation via mobile devices, especially smartphones simple, beyond the space provided for this application in education. The article deals the creation, software and hardware that provide an interactive and dynamic way to attract more students to use these experiments remote, serving as support to teachers to science teaching from its initial series. The ease and availability of smartphones, even these students of basic education, permits the reach of new users and in different places. Thus, the practice of remote experimentation in mobile devices enables new spaces for access and interaction. Are used for developing software free or low cost, HTML5 and jQuery Mobile framework, that enable the creation of pages compatible with different mobile operating systems such as iOS, Android, Windows Phone, some Symbian, among others. Also are demonstrated patterns layouts that allow greater accessibility.

Using remote labs to serve different teacher's needs a case study with VISIR and RemotElectLab

Remote Laboratories are an emergent technological and pedagogical tool at all education levels, and their widespread use is an important part of their own improvement and evolution. This paper describes several issues encountered on laboratorial classes, on higher education courses, when using remote laboratories based on PXI systems, either using the VISIR system or an alternate in-house solution. Three main issues are presented and explained, all reported by teachers that gave support to students use of remote laboratories. The first issue deals with the need to allow students to select the actual place where an ammeter is to be inserted on electric circuits, even incorrectly, therefore emulating real world difficulties. The second one deals with problems with timing when several measurements are required at short intervals, as in the discharge cycle of a capacitor. And the last issue deals with the use of a multimeter in DC mode when reading AC values, a use that collides with the lab settings. All scenarios are presented and discussed including the solution found for each case. The conclusion derived from the described work is that the remote laboratories area is an expanding field, where practical use leads to improvement and evolution of the available solutions, requiring a strict cooperation and information sharing between all actors, i.e. developers, teachers and students.

Reconfigurable IEEE1451-FPGA based weblab infrastructure

Weblabs are spreading their influence in Science and Engineering (S&E) courses providing a way to remotely conduct real experiments. Typically, they are implemented by different architectures and infrastructures supported by Instruments and Modules (I&Ms) able to be remotely controlled and observed. Besides the inexistence of a standard solution for implementing weblabs, their reconfiguration is limited to a setup procedure that enables interconnecting a set of preselected I&Ms into an Experiment Under Test (EUT). Moreover, those I&Ms are not able to be replicated or shared by different weblab infrastructures, since they are usually based on hardware platforms. Thus, to overcome these limitations, this paper proposes a standard solution that uses I&Ms embedded into Field-Programmable Gate Array (FPGAs) devices. It is presented an architecture based on the IEEE1451.0 Std. supported by a FPGA-based weblab infrastructure able to be remotely reconfigured with I&Ms, described through standard Hardware Description Language (HDL) files, using a Reconfiguration Tool (RecTool).

As tendências do ensino e da investigação académica na história da contabilidade em Portugal

Dissertação de Mestrado apresentada ao Instituto de Contabilidade e Administração do Porto para a obtenção do grau de Mestre em Contabilidade e Finanças, sob orientação da Professora Doutora Ana Maria Alves Bandeira

Choosing amine-based absorbents for CO2 capture

CO2 capture from gaseous effluents is one of the great challenges faced by chemical and environmental engineers, as the increase in CO2 levels in the Earth atmosphere might be responsible for dramatic climate changes. From the existing capture technologies, the only proven and mature technology is chemical absorption using aqueous amine solutions. However, bearing in mind that this process is somewhat expensive, it is important to choose the most efficient and, at the same time, the least expensive solvents. For this purpose, a pilot test facility was assembled and includes an absorption column, as well as a stripping column, a heat exchanger between the two columns, a reboiler for the stripping column, pumping systems, surge tanks and all necessary instrumentation and control systems. Some different aquous amine solutions were tested on this facility and it was found that, from a set of six tested amines, diethanol amine is the one that turned out to be the most economical choice, as it showed a higher CO2 loading capacity (0.982 mol of CO2 per mol of amine) and the lowest price per litre (25.70 ¤/L), even when compared with monoethanolamine, the benchmark solvent, exhibiting a price per litre of 30.50 ¤/L.

Fast unsupervised technique for extraction of endmembers spectra from hyperspectral data

One of the most challenging task underlying many hyperspectral imagery applications is the linear unmixing. The key to linear unmixing is to find the set of reference substances, also called endmembers, that are representative of a given scene. This paper presents the vertex component analysis (VCA) a new method to unmix linear mixtures of hyperspectral sources. The algorithm is unsupervised and exploits a simple geometric fact: endmembers are vertices of a simplex. The algorithm complexity, measured in floating points operations, is O (n), where n is the sample size. The effectiveness of the proposed scheme is illustrated using simulated data.

Estruturas de Suporte de Terras Executadas com Pneus - Modelo à Escala Reduzida

Mestrado em Engenharia Civil – Ramo de Estruturas