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Influência da longevidade da solução de Verhoeff na intensidade/especificidade ...

As fibras elásticas são responsáveis pela elasticidade e flexibilidade dos tecidos. A técnica de Verhoeff é o método mais utilizado para demonstrar a presença destas fibras, corando-as de preto. A solução de Verhoeff é exclusivamente utilizada de um modo extemporâneo, no entanto, pela revisão da literatura verificou-se que a mesma poderia ter uma maior durabilidade. O presente estudo tem como principal objectiv...

Very high position resolution gamma imaging with resistive plate chambers

In this study we present experimental results from a first prototype of a positron emission tomography system based on the resistive plate chamber (RPC) technology. The system is composed of two counting heads, each one containing 16 single-gap RPC detectors capable of detecting the photon interaction point in the transaxial plane. Uniformity studies were performed for image resolution and sensitivity, yielding...

Spatial resolution on a small animal RPC-PET prototype operating under magnetic...

It has been demonstrated in previous work that the RPC-PET technology is able to deliver radioisotope image resolutions approaching the physical limits of the PET principle. Here we study, by simulation, the effect of the magnetic field on the positron range to evaluate whether the spatial resolution of the RPC-PET could be improved by using an intense magnetic field. Six positron emitters of interest to small ...

A percepção dos profissionais de saúde face ao exercício físico em transplantad...

O exercício físico (EF) em transplantados renais (TR) é um tema que tem vindo a sofrer alterações ao longo dos tempos. Inicialmente prevalecia o princípio da minimização do risco, em que se procurava proteger o órgão transplantado de possíveis riscos decorrentes do EF. Presentemente valoriza-se a maximização dos diversos benefícios que o EF pode proporcionar a esta população especial. Contudo, estudos revelam, ...

A formação inicial de professores do 1º CEB nas últimas três décadas do séc. XX...

Progress in timing Resistive Plate Chambers

Timing RPCs are Resistive Plate Chambers made with glass and metal electrodes separated by precision spacers. Typical gas gaps are a few hundred micrometers wide. Such counters were introduced in 1999 and have since reached timing accuracies below 50 ps [sigma] with efficiencies above 99% for MIPs. Applications in high-energy physics have already taken place with several more under study. ; http://www.scienc...

A large area timing RPC prototype for ion collisions in the HADES spectrometer

We present a resistive plate chamber (RPC) prototype for time-of-flight measurements over large areas and at high occupancies, minimizing the inter-channel cross-talk. ; http://www.sciencedirect.com/science/article/B6TJM-4D75GPD-9/1/a6fe40c114a867a0f98e2fec0f133503

Performance of shielded timing RPCs in a 12C fragmentation experiment

We show the feasibility of large area timing RPC detectors for experiments dealing with fragmentation-like primary interactions and/or high detector multiplicities, without significative degradation of the detector capabilities. The tested prototype is constituted by three independent cells placed into grounded aluminium boxes, which reduce the cross-talk to the level of 0.4%. Each box consists of a 4-gap glass...

An RPC-PET prototype with high spatial resolution

A small positron emission tomography system, based on the timing RPC technology has been built and tested. This first prototype is aimed at validating the expectations, derived from simulations, of a very high spatial resolution, which could be of value for the imaging of small animals. The system is composed of two counting heads, able to measure the photon interaction point in two dimensions, the transaxial d...