Study of the influence of count���s number in myocardium in the determination of reproducible functional parameters in Gated-SPECT studies simulated with GATE

Myocardial Perfusion Gated Single Photon Emission Tomography (Gated-SPET) imaging is used for the combined evaluation of myocardial perfusion and left ventricular (LV) function. But standard protocols of the Gated-SPECT studies require long acquisition times for each study. It is therefore important to reduce as much as possible the total duration of image acquisition. However, it is known that this reduction leads to decrease on counts statistics per projection and raises doubts about the validity of the functional parameters determined by Gated-SPECT. Considering that, it���s difficult to carry out this analysis in real patients. For ethical, logistical and economical matters, simulated studies could be required for this analysis. Objective: Evaluate the influence of the total number of counts acquired from myocardium, in the calculation of myocardial functional parameters (LVEF ��� left ventricular ejection fraction, EDV ��� end-diastolic volume, ESV ��� end-sistolic volume) using routine software procedures.

Design of a Multiband Full-Rate Ultra-Wideband Receiver in FPGA

MultiBand OFDM (MB-OFDM) UWB [1] is a short-range promising wireless technology for high data rate communications up to 480 Mbps. In this paper, we have designed and implemented in an Virtex-6 FPGA an MB-OFDM UWB receiver for the highest data rate of 480 Mbps. To test the system, we have also implemented an MB-OFDM transmitter and an AWGN generator in VHDL and determined the bit error rates at the receiver running in an FPGA.

Preparatory and field work phases in the qualitative empirical research process in management: the case studies approach

Purpose: The aim of this paper is to promote qualitative methodology within the scientific community of management. The specific objective is oriented to propose an empirical research process based on case study method. This is to ensure rigor in the empirical research process, that future research may follow a similar procedure to that is proposed. Design/methodology/approach: Following a qualitative methodological approach, we propose a research process that develops according to four phases, each with several stages. This study analyses the preparatory and field work phases and their stages. Findings: The paper shows the influence that case studies have on qualitative empirical research process in management. Originality/value:. Case study method assumes an important role within qualitative research by allowing for the study and analysis of certain types of phenomena that occur inside organisations, and in respect of which quantitative studies cannot provide an answer.

Embedded platform for ECG biometric recognition

Trabalho Final de Mestrado para obten����o do grau de Mestre em Engenharia de Electr��nica e Telecomunica����es

Projecto de uma c��mara em rede em FPGA

Trabalho Final de Mestrado para obten����o do grau de Mestre em Engenharia de Electr��nica e Telecomunica����es

Sistema de multiprocessamento para simula����o de N-corpos em FPGA

Trabalho Final de Mestrado para obten����o do grau de Mestre em Engenharia de Electr��nica e Telecomunica����es

Sistema de teste de trans��stores bipolares de jun����o e de efeito de campo

O estudo das curvas caracter��sticas de um trans��stor permite conhecer um conjunto de par��metros essenciais �� sua utiliza����o tanto no dom��nio da amplifica����o de sinais como em circuitos de comuta����o. Deste estudo �� poss��vel obter dados em condi����es que muitas vezes n��o constam na documenta����o fornecida pelos fabricantes. O trabalho que aqui se apresenta consiste no desenvolvimento de um sistema que permite de forma simples, eficiente e econ��mica obter as curvas caracter��sticas de um trans��stor (bipolar de jun����o, efeito de campo de jun����o e efeito de campo de metal-��xido semicondutor), podendo ainda ser utilizado como instrumento pedag��gico na introdu����o ao estudo dos dispositivos semicondutores ou no projecto de amplificadores transistorizados. O sistema �� constitu��do por uma unidade de condicionamento de sinal, uma unidade de processamento de dados (hardware) e por um programa inform��tico que permite o processamento gr��fico dos dados obtidos, isto ��, tra��ar as curvas caracter��sticas do trans��stor. O seu princ��pio de funcionamento consiste na utiliza����o de um conversor Digital-Anal��gico (DAC) como fonte de tens��o vari��vel, alimentando a base (TBJ) ou a porta (JFET e MOSFET) do dispositivo a testar. Um segundo conversor fornece a varia����o da tens��o VCE ou VDS necess��ria �� obten����o de cada uma das curvas. O controlo do processo �� garantido por uma unidade de processamento local, baseada num microcontrolador da fam��lia 8051, respons��vel pela leitura dos valores em corrente e em tens��o recorrendo a conversores Anal��gico-Digital (ADC). Depois de processados, os dados s��o transmitidos atrav��s de uma liga����o USB para um computador no qual um programa procede �� representa����o gr��fica, das curvas caracter��sticas de sa��da e �� determina����o de outros par��metros caracter��sticos do dispositivo semicondutor em teste. A utiliza����o de componentes convencionais e a simplicidade construtiva do projecto tornam este sistema econ��mico, de f��cil utiliza����o e flex��vel, pois permite com pequenas altera����es

Controlador Boundary-Scan

A crescente complexidade dos sistemas electr��nicos associada a um desenvolvimento nas tecnologias de encapsulamento levou �� miniaturiza����o dos circuitos integrados, provocando dificuldades e limita����es no diagn��stico e detec����o de falhas, diminuindo drasticamente a aplicabilidade dos equipamentos ICT. Como forma de lidar com este problema surgiu a infra-estrutura Boundary Scan descrita na norma IEEE1149.1 ���Test Access Port and Boundary-Scan Architecture���, aprovada em 1990. Sendo esta solu����o tecnicamente vi��vel e interessante economicamente para o diagn��stico de defeitos, efectua tamb��m outras aplica����es. O SVF surgiu do desejo de incutir e fazer com que os fornecedores independentes inclu��ssem a norma IEEE 1149.1, �� desenvolvido num formato ASCII, com o objectivo de enviar sinais, aguardar pela sua resposta, segundo a m��scara de dados baseada na norma IEEE1149.1. Actualmente a incorpora����o do Boundary Scan nos circuitos integrados est�� em grande expans��o e consequentemente usufrui de uma forte implementa����o no mercado. Neste contexto o objectivo da disserta����o �� o desenvolvimento de um controlador boundary scan que implemente uma interface com o PC e possibilite o controlo e monitoriza����o da aplica����o de teste ao PCB. A arquitectura do controlador desenvolvido cont��m um m��dulo de Mem��ria de entrada, um Controlador TAP e uma Mem��ria de sa��da. A implementa����o do controlador foi feita atrav��s da utiliza����o de uma FPGA, �� um dispositivo l��gico reconfigur��veis constitu��do por blocos l��gicos e por uma rede de interliga����es, ambos configur��veis, que permitem ao utilizador implementar as mais variadas fun����es digitais. A utiliza����o de uma FPGA tem a vantagem de permitir a versatilidade do controlador, facilidade na altera����o do seu c��digo e possibilidade de inserir mais controladores dentro da FPGA. Foi desenvolvido o protocolo de comunica����o e sincroniza����o entre os v��rios m��dulos, permitindo o controlo e monitoriza����o dos est��mulos enviados e recebidos ao PCB, executados automaticamente atrav��s do software do Controlador TAP e de acordo com a norma IEEE 1149.1. A solu����o proposta foi validada por simula����o utilizando o simulador da Xilinx. Foram analisados todos os sinais que constituem o controlador e verificado o correcto funcionamento de todos os seus m��dulos. Esta solu����o executa todas as sequ��ncias pretendidas e necess��rias (envio de est��mulos) �� realiza����o dos testes ao PCB. Recebe e armazena os dados obtidos, enviando-os posteriormente para a mem��ria de sa��da. A execu����o do trabalho permitiu concluir que os projectos de componentes electr��nicos tender��o a ser descritos num n��vel de abstrac����o mais elevado, recorrendo cada vez mais ao uso de linguagens de hardware, no qual o VHDL �� uma excelente ferramenta de programa����o. O controlador desenvolvido ser�� uma ferramenta bastante ��til e vers��til para o teste de PCBs e outras funcionalidades disponibilizadas pelas infra-estruturas BS.

Integra����o da tecnologia Near Field Communications nas telecomunica����es m��veis

O telem��vel tem-se transformado numa ferramenta essencial no nosso dia-a-dia, constantemente s��o lan��adas novas tecnologias que potenciam o uso do telem��vel nas tarefas do nosso quotidiano. Atualmente a grande tend��ncia passa por fazer o download de aplica����es com o objetivo de obter mais e diferentes tipos de informa����o, existe o desejo de ler de forma simples e intuitiva o mundo que nos rodeia, como se cada elemento fosse um objeto sobre o qual conseguiremos obter informa����o atrav��s do telem��vel. A tecnologia Near Field Communication (NFC) ajuda a transformar este desejo ou necessidade numa realidade de simples alcance. Podemos anexar ���identificadores��� nos objetos e ���ver��� estes identificadores atrav��s do telem��vel recorrendo a aplica����es que fazem a ponte com os sistemas que nos permitem obter mais informa����o, por exemplo, internet. O NFC especifica um padr��o de comunica����o de redes sem fios, que permite a transfer��ncia de dados entre dois dispositivos separados por uma dist��ncia m��xima de 10cm. NFC foi desenhado para ser integrado em telem��veis, que podem comunicar com outros telem��veis equipados com NFC ou ler informa����o de cart��es ou tags. A disserta����o avalia as oportunidades que a tecnologia NFC oferece ao mundo das telecomunica����es m��veis, nomeadamente na realidade do operador Vodafone Portugal, principalmente numa rela����o Empresa - Cliente. Esta tecnologia re��ne o interesse dos fabricantes dos telem��veis, dos operadores e de parceiros cr��ticos que v��o ajudar a potenciar o neg��cio, nomeadamente entidades banc��rias e interbanc��rias. A tecnologia NFC permite utilizar o telem��vel como um cart��o de cr��dito/debito, ticketing, ler informa����o de posters (Smart Poster) que despoletem navega����o contextualizada para outras aplica����es ou para a internet para obter mais informa����o ou concretizar compras, estes s��o alguns cen��rios identificados que mais valor o NFC consegue oferecer. A disserta����o foca-se na avalia����o t��cnica do NFC na ��rea de Smart Posters e resulta na identifica����o num conjunto de novos cen��rios de utiliza����o, que s��o especificados e complementados com o desenvolvimento de um prot��tipo.

Capillary bridging and long-range attractive forces in a mean-field approach

When a mixture is confined, one of the phases can condense out. This condensate, which is otherwise metastable in the bulk, is stabilized by the presence of surfaces. In a sphere-plane geometry, routinely used in atomic force microscope and surface force apparatus, it, can form a bridge connecting the surfaces. The pressure drop in the bridge gives rise to additional long-range attractive forces between them. By minimizing the free energy of a binary mixture we obtain the force-distance curves as well as the structural phase diagram of the configuration with the bridge. Numerical results predict a discontinuous transition between the states with and without the bridge and linear force-distance curves with hysteresis. We also show that similar phenomenon can be observed in a number of different systems, e.g., liquid crystals and polymer mixtures. (C). 2004 American Institute of Physics.

Radiatively induced Lorentz and CPT violation in Schwinger constant field approximation

The Schwinger proper-time method is an effective calculation method, explicitly gauge-invariant and nonperturbative. We make use of this method to investigate the radiatively induced Lorentz- and CPT-violating effects in quantum electrodynamics when an axial-vector interaction term is introduced in the fermionic sector. The induced Lorentz- and CPT-violating Chern-Simons term coincides with the one obtained using a covariant derivative expansion but differs from the result usually obtained in other regularization schemes. A possible ambiguity in the approach is also discussed. (C) 2001 Published by Elsevier Science B.V.

A multiresidue method for the analysis of carbamate and urea pesticides from soils by microwave-assisted extraction and liquid chromatography with photodiode array detection

A multiresidue approach using microwave-assisted extraction and liquid chromatography with photodiode array detection was investigated for the determination of butylate, carbaryl, carbofuran, chlorpropham, ethiofencarb, linuron,metobromuron, and monolinuron in soils. The critical parameters of the developed methodology were studied. Method validation was performed by analyzing freshly and aged spiked soil samples. The recoveries and relative standard deviations reached using the optimized conditions were between 77.0 �� 0.46% and 120 �� 2.9% except for ethiofencarb (46.4 �� 4.4% to 105 �� 1.6%) and butylate (22.1 �� 7.6% to 49.2 �� 11%). Soil samples from five locations of Portugal were analysed.

Screening of grapes and wine for azoxystrobin, kresoxim-methyl and trifloxystrobin fungicides by HPLC with diode array detection

The Quinone outside Inhibitors (QoI) are one of the most important and recent fungicide groups used in viticulture and also allowed by Integrated Pest Management. Azoxystrobin, kresoxim-methyl and trifloxystrobin are the main active ingredients for treating downy and powdery mildews that can be present in grapes and wines. In this paper, a method is reported for the analysis of these three QoI-fungicides in grapes and wine. After liquid���liquid extraction and a clean-up on commercial silica cartridges, analysis was by isocratic HPLC with diode array detection (DAD) with a run time of 13 min. Confirmation was by solid-phase micro-extraction (SPME), followed by GC/MS determination. The main validation parameters for the three compounds in grapes and wine were a limit of detection up to 0.073mg kg-1, a precision not exceeding 10.0% and an average recovery of 93% ��38.

The influence of count's number in myocardium in the determination of reproducible parameters in Gated-SPECT studies simulated with GATE

Myocardial Perfusion Gated Single Photon Emission Tomography (Gated-SPET) imaging is used for the combined evaluation of myocardial perfusion and left ventricular (LV). The purpose of this study is to evaluate the influence of the total number of counts acquired from myocardium, in the calculation of myocardial functional parameters using routine software procedures. Methods: Gated-SPET studies were simulated using Monte Carlo GATE package and NURBS phantom. Simulated data were reconstructed and processed using the commercial software package Quantitative Gated-SPECT. The Bland-Altman and Mann-Whitney-Wilcoxon tests were used to analyze the influence of the number of total counts in the calculation of LV myocardium functional parameters. Results: In studies simulated with 3MBq in the myocardium there were significant differences in the functional parameters: Left ventricular ejection fraction (LVEF), end-systolic volume (ESV), Motility and Thickness; between studies acquired with 15s/projection and 30s/projection. Simulations with 4.2MBq show significant differences in LVEF, end-diastolic volume (EDV) and Thickness. Meanwhile in the simulations with 5.4MBq and 8.4MBq the differences were statistically significant for Motility and Thickness. Conclusion: The total number of counts per simulation doesn't significantly interfere with the determination of Gated-SPET functional parameters using the administered average activity of 450MBq to 5.4MBq in myocardium.

Determination of methiocarb and Its degradation products, methiocarb sulfoxide and methiocarb sulfone, in bananas using QuEChERS extraction

The present work describes the development of an analytical method for the determination of methiocarb and its degradation products (methiocarb sulfoxide and methiocarb sulfone) in banana samples, using the QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure followed by liquid chromatography coupled to photodiode array detector (LCPAD). Calibration curves were linear in the range of 0.5���10 mg L���1 for all compounds studied. The average recoveries, measured at 0.1 mg kg���1 wet weight, were 92.0 (RSD = 1.8%, n = 3), 84.0 (RSD = 3.9%, n = 3), and 95.2% (RSD = 1.9%, n = 3) for methiocarb sulfoxide, methiocarb sulfone, and methiocarb, respectively. Banana samples treated with methiocarb were collected from an experimental field. The developed method was applied to the analysis of 24 samples (peel and pulp) and to 5 banana pulp samples. Generally, the highest levels were found for methiocarb sulfoxide and methiocarb. Methiocarb sulfone levels were below the limit of quantification, except in one sample (not detected).