An array of fabry-perot optical-channels for biological fluids analysis

This paper describes a biosystem (biological system) used to measure the concentration of biochemical substances in urine, serum, plasma or cerebrospinal fluid. Rather than just one channel, it comprises 16 optical-channels that enable the measurement of the concentration of 16 different biochemical substances. An array of 16 optical filters based on Fabry-Perot thin-films optical resonators has been designed. Each optical-channel is sensitive in a single wavelength with a full-width-half-maximum (FWHM) of 7 nm. The filter fabrication requires only four masks, used with different etch time. A commercially available band-pass optical filter with a band-pass wavelength in 450–650 nm is used. The biosystem requires only a white light source for illumination due the use of selective optical filters.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/1281/2000, POCTI/33747/ESE/1999 – Fundo Europeu para o Desenvolvimento Regional

In or out? Barriers and facilitators to refugee-background young people accessing mental health services

Refugee young people have been identified as a group with high risk for mental health problems, due to their experience of trauma, forced migration, and stressors associated with settlement. A high prevalence of mental health problems is reported in this group, however some research suggests refugee young people have low rates of mental health service access. There is little information available on barriers and facilitators to mental service delivery for this group. Using data from 15 focus groups and five key informant interviews with a total of 115 service providers from 12 agencies in Melbourne, Australia, this paper explores barriers and facilitators to engaging young people from refugee backgrounds with mental health services. Eight key themes emerged: cultural concepts of mental health, illness, and treatment; service accessibility; trust; working with interpreters; engaging family and community; the style and approach of mental health providers; advocacy; and continuity of care

Scintillating microcavities for X-ray imaging sensors

Over the last years several prototypes of detectors for digital radiography, based on different approaches, have been developed. One those approaches is based on scintillating crystals, which convert the x-ray energy into visible light that will be detected by photodetectors. The biggest difficulty of this kind of detectors is the fact that the produced visible light must be guided to the photodetectors. This can be achieved through coating of reflective material on and around each scintillator. This article describes the fabrication process of an x-ray detector based on scintillators and walls of a reflective material, aluminum, which guide the visible light to the photodetectors placed below the scintillators

Do fim ao recomeço: um estudo do conto O vaso azul, de João Anzanello Carrascoza

Esta pesquisa tem como eixo o estudo do conto O vaso azul, do escritor paulista contemporâneo João Anzanello Carrascoza. Estrutura-se em três momentos: apresentação crítica da obra do autor, cotejo das três versões existentes do conto, com reflexões acerca das operações efetuadas no processo de reescrita e, por fim, uma interpretação do texto, em que se buscaram diálogos, não apenas literários, como também interartes

A tunable Fabry-Perot optical filter for application in biochemical analysis of human’s fluids

This paper reports a Fabry-Perot tunable optical filter for application in clinical analysis, especially to measure the concentration of biochemical substances in biological fluids. Its tunable characteristics enable the measurement of different biochemical substances with the same device. It is composed of two parallel thin silver mirrors with a β-PVDF (Poly(Vinylidene Fluoride) in its β phase) film in-between as the resonance cavity. The filter is tuned by adjusting the space between the mirrors through an electric voltage inducing dipolar orientation in the β-PVDF film. Once the thickness changes of the β-PVDF film is due to variations at a molecular level, the changes are rather homogeneous within the samples. As a result, this approach achieves parallelism between the two mirrors, which is a complex problem to solve in conventional Fabry-Perot optical filters. Moreover, compared with an array of non-tunable optical filters with different cavity lengths, usually used to solve the parallelism problem, this device has a reduced area, its fabrication process is easier and it covers a wider spectral range. In addition, when used as a part of a biological fluids analysis system, it avoids the need for expensive optics and enables low-cost and portable devices, which would improve the use of spectrophotometric analysis in clinical diagnostics.R&D Centro Algoritmi da Universidade do Minho.Escola de Engenharia da Universidade do Minho - program IN2TEC.Fundação para a Ciência e a Tecnologia (FCT) - Grant POCI/CTM/59425/2004

Biological microsystem for measuring uric acid in biological fluids

This paper describes a biological microsystem (bio-system) for measuring uric acid concentration in serum, plasma or urine. Its operation is based on optical absorption in a well-defined part of the visible spectrum. The bio-system is composed by two dies: one is fabricated in polystyrene and contains the microchannels and the other is fabricated in a CMOS standard process and contains the photodetector and readout electronics. The uric acid concentration is measured by using a mixture of 14µl of infinity™ uric acid reagent with 0.25µl of sample. The achieved sensitivity is 0.33 mg/dl (±0.6% of the value in urine of a healthy person), with a 1mm lightpath. Using an optical absorption method, a maximum peak at wavelength λ = 494 nm, is detected. This bio-system can be included in the group of low-cost disposable devices for biological fluids analysis.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/1281/2000, POCTI/33747/ESE/1999), FEDER

Characterization of silicon photodiodes for diffuse reflectance signal extraction

Early detection of gastrointestinal (GI) can cers is one of most important concerns in medical field. Its detection at the earliest stage is crucial to increase the patient survival chances. Optical signals extraction and analysis, specifically diffuse reflectance and intrinsic fluorescence, may impr ove the ability to detect GI dysplasia, once some morphological and biochemical changes on the tissues (related with early cancer progre ssion) can modify these signals’ shape and intensity. The project under th is paper aims to develop a chip - sized spectros copy microsystem for the early detection of GI cancer. This paper presents the characterization of silicon photodiodes (n+/p - epilayer type) fabricated in a standard 0.7 μm CMOS process, with different dimensions. The main goal is to conclude which photodio de must be fabricated for the microsystem implementation, taking into account its capacity to extract the signals in the relevant spectral band (350 nm – 750 nm), not comprising the microsystem dimensions. With this study , it can be conclude d that the suit able photodiodes for the detection of those spectroscopic signals are the ones with 125 × 125 μm 2 or 100 × 100 μm 2 active area , once their quantum efficiency varies between 20% and 55%, approximately, above 450 nm. In spite of the low photodiod es quantum efficiency (lower than 20%) below 450 nm, the viability of using the 100 × 100 μm 2 photodiode to extract the diffuse reflectance signal, between 350 nm and 750 nm, was proven using a test phantom representative of a GI tissue.This work is funded by FEDER funds through the "Eixo I do Programa Operacional Fatores de Competitividade (POFC) QREN, projects reference COMPETE: FCOMP-01-0124-FEDER-020241 and FCOMP-01-124-FEDER-037291 (PEst-C/FIS/UI0607/2013) and by FCT – Fundação para a Ciência e a Tecnologia, project reference PTDC/EBB-EBI/120334/2010. S. Pimenta thanks the FCT for the SFRH/BD/87605/2012 PhD grant

Fluorescence and diffuse reflectance spectroscopy for early cancer detection using a new strategy towards the development of a miniaturized system

This paper describes the design of a miniature, cost-effective spectroscopy system for assessing tissue biochemical and morphological information using a few wavelengths. This instrument will integrate thin-film optical filters and silicon photodiodes, avoiding the use of a spectrograph and optical fibers. The components in the set-up design are described. The feasibility of using only 16 wavelengths to accurately extract tissue properties is confirmed on physical tissue models. Also, the suitable spectral performance of several optical filters for the selection of these wavelengths is demonstrated. The small size of this device will enable implementation in an endoscopic capsule.This research was supported by the Portuguese Foundation of Science and Technology and the MIT|Portugal Program (SFRH/BD/38978/2007

Modeling and simulation of the mixing process of fluids in microchannels promoted by acoustic streaming

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.This work describes a study on the acoustic streaming phenomenon, for promoting mixing in microfluidic channels. Acoustic microagitation is a solution to overcome the slow molecular diffusion and accelerate chemical reactions, which is essential to the success of microfluidic devices. A preliminary study has been performed on the piezoelectric effect generated by an electroactive polymer and on the compressible flow Navier-Stokes equations. The simulations were based on finite elements numerical methods. It was concluded that the positioning of the transducer influences the pressure distribution over the fluid domain. It was also seen that the Navier-Stokes equations can be expanded as a sum of equilibrium, first and second order values, that describe the damped propagation of acoustic waves and the global flow, respectively. The time average of the first order results corresponds to a force and can be applied as a source term in the second order equations to determine the mean global flow into the microcuvette.Programa Operacional Factores de Competitividade – COMPETE and FCT- Fundação para a Ciência e a Tecnologia project reference PTDC/BIO/70017/2006 and SFRH/BD/61767/200

Population-based studies of myocardial hypertrophy: high resolution cardiovascular magnetic resonance atlases improve statistical power

BACKGROUND: Cardiac phenotypes, such as left ventricular (LV) mass, demonstrate high heritability although most genes associated with these complex traits remain unidentified. Genome-wide association studies (GWAS) have relied on conventional 2D cardiovascular magnetic resonance (CMR) as the gold-standard for phenotyping. However this technique is insensitive to the regional variations in wall thickness which are often associated with left ventricular hypertrophy and require large cohorts to reach significance. Here we test whether automated cardiac phenotyping using high spatial resolution CMR atlases can achieve improved precision for mapping wall thickness in healthy populations and whether smaller sample sizes are required compared to conventional methods. METHODS: LV short-axis cine images were acquired in 138 healthy volunteers using standard 2D imaging and 3D high spatial resolution CMR. A multi-atlas technique was used to segment and co-register each image. The agreement between methods for end-diastolic volume and mass was made using Bland-Altman analysis in 20 subjects. The 3D and 2D segmentations of the LV were compared to manual labeling by the proportion of concordant voxels (Dice coefficient) and the distances separating corresponding points. Parametric and nonparametric data were analysed with paired t-tests and Wilcoxon signed-rank test respectively. Voxelwise power calculations used the interstudy variances of wall thickness. RESULTS: The 3D volumetric measurements showed no bias compared to 2D imaging. The segmented 3D images were more accurate than 2D images for defining the epicardium (Dice: 0.95 vs 0.93, P < 0.001; mean error 1.3 mm vs 2.2 mm, P < 0.001) and endocardium (Dice 0.95 vs 0.93, P < 0.001; mean error 1.1 mm vs 2.0 mm, P < 0.001). The 3D technique resulted in significant differences in wall thickness assessment at the base, septum and apex of the LV compared to 2D (P < 0.001). Fewer subjects were required for 3D imaging to detect a 1 mm difference in wall thickness (72 vs 56, P < 0.001). CONCLUSIONS: High spatial resolution CMR with automated phenotyping provides greater power for mapping wall thickness than conventional 2D imaging and enables a reduction in the sample size required for studies of environmental and genetic determinants of LV wall thickness