Abstract
Local pulse-wave velocity (PWV) is an accurate indicator of the degree of arteriosclerosis (stiffness) in an artery, providing a direct characterization of the properties of its wall. Devices currently available for local PWV measurement are mainly based on ultrasound systems and have not yet been generalized to clinical practice since they require high technical expertise and most of them are limited in precision, due to the lack of reliable signal processing methods. The present work describes a new type of probe, based on a double-headed piezoelectric (PZ) sensor. The principle of PWV measurement involves determination of the pulse transit time between the signals acquired simultaneously by both PZs, placed 23 mm apart. The double probe (DP) characterization is accomplished in three main studies, carried out in a dedicated test bench system, capable of reproducing a range of clinically relevant properties of the cardiovascular system. The first study refers to determination of the impulse response (IR) for each PZ sensor, whereas the second one explores the existence of crosstalk between both transducers. In the last one, DP time resolution is inferred from a set of three different algorithms based on (a) the maximum of cross-correlation function, (b) the maximum amplitude detection and (c) the zero-crossing point identification. These values were compared with those obtained by the reference method, which consists of the simultaneous acquisition of pressure waves by means of two pressure sensors. The new probe demonstrates good performance on the test bench system and results show that the signals do not exhibit crosstalk. A good agreement was also verified between the PWV obtained from the DP signals (19.55 +/- 2.02 ms(-1)) and the PWV determined using the reference method (19.26 +/- 0.04 ms(-1)). Although additional studies are still required, this probe seems to be a valid alternative to local PWV stand-alone devices.

Abstract
We developed and tested the performance of a new wavelet based algorithm for Augmentation Index (AIx) determination. The evaluation method relies on reference cardiac-like pulses that are synthesized using a weighted combination of exponentially shaped sub-pulses that represent the three main components of real pulses: the systolic stroke, its reflected replica and the carotid reservoir or windkessel effect. The pulses are parameterized so as to reproduce the main types of cardiac waveforms. The values of AIx yielded by the new algorithm are compared with the ones computed directly from the synthesized waveform and with the values produced by standard Probability Density Function (PDF) analysis.

Abstract
Skeletal muscle presents an internal fibrous structure. The existence of muscle fibers surrounded by interstitial fluid originates an internal step refractive index profile that causes light scattering. One way to minimize this effect inside a muscle is to perform an optical clearing treatment, using an adequate solution that presents a refractive index higher than the interstitial fluid. We have studied muscle spectral transmittance during sample immersion in propylene glycol. With the collection of transmittance spectra registered during a period of 20 minutes of immersion we could represent spectral transmittance evolution for several wavelengths and verify that the tissue samples have become more translucent. The optical clearing effect created in the tissue samples was characterized by an increase of 45% above the natural transmittance and the variations observed in tissue mass, pH and global refractive index. We also identified the initial mechanisms of agent diffusion into the tissue and consequent tissue dehydration from the spectral transmittance evolution. The histological analysis of variations caused in the internal structure of the tissues permitted to better explain the optical clearing effect created. Considering a mathematical model developed in previous studies, we could estimate the amount of agent that was inserted into the tissue samples.

Abstract
It is known that the fibrous structure of muscle causes light scattering. This phenomenon occurs due to the refractive index discontinuities located between muscle fibers and interstitial fluid. To study the possibility of reducing light scattering inside muscle, we consider its spectral transmittance evolution during an immersion treatment with an optical clearing solution containing ethanol, glycerol, and distilled water. Our methodology consists of registering spectral transmittance of muscle samples while immersed in that solution. With the spectral data collected, we represent the transmittance evolution for some wavelengths during the treatment applied. Additionally, we study the variations that the treatment has caused on the samples regarding tissue refractive index and mass. By analyzing microscopic photographs of tissue cross section, we can also verify changes in the internal arrangement of muscle fibers caused by the immersion treatment. Due to a mathematical model that we develop, we can explain the variations observed in the studied parameters and estimate the amount of optical clearing agent that has diffused into the tissue samples during the immersion treatment. At the end of the study, we observe and explain the improvement in tissue spectral transmittance, which is approximately 65% after 20 min. (C) 2010 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3486539]

Abstract
When accessing and interacting with regular electronic devices or informatics systems, users frequently depend on the sight sense because the information is, consistently, presented in a visual format, despite the feasibility to use additional formats, such as audio. It also happens that the access to the information systems is triggered by the action of the users, hence requiring an awareness of the surrounding environment. These two facts lead to an exclusion of a considerable number of citizens, such as the visually impaired ones, from a fair access to the so-called Information Society. The development of automatic user-aware Interactive Voice Response (IVR) systems can be an interesting solution to this issue, particularly, if the communications are done in a private manner and a low-cost implementation is achieved. In a reply to this challenge, it was formulated a pervasive user detection and communication concept, based on Bluetooth technology and Linux software modules, allowing improved interaction between the personal area information systems and the mobile user devices. To demonstrate the validity of the concept, it was developed a personal area IVR system, based on Linux, being the interaction with the users made by means of the Bluetooth technology.

Abstract