Time filter

Source Type

Covilha, Portugal

The University of Beira Interior is a public university located in the city of Covilhã, Portugal. It was created in 1979, and has about 7,110 students distributed across a multiplicity of graduation courses, awarding all academic degrees in fields ranging from medicine and biomedical science to aeronautical engineering to mathematics. The university is named after the historical Beira region, meaning Beira Interior the most interior area of Beira, mainly composed by the district of Guarda and the district of Castelo Branco, in today's Centro region. Wikipedia.

Proenca H.,University of Beira Interior
IEEE Transactions on Information Forensics and Security

Data quality assessment is a key issue, in order to broaden the applicability of iris biometrics to unconstrained imaging conditions. Previous research efforts sought to use visible wavelength (VW) light imagery to acquire data at significantly larger distances than usual and on moving subjects, which makes this real-world data notoriously different from the acquired in the near-infrared setup. Having empirically observed that published strategies to assess iris image quality do not handle the specificity of such data, this paper proposes a method to assess the quality of VW iris samples captured in unconstrained conditions, according to the factors that are known to determine the quality of iris biometric data: focus, motion, angle, occlusions, area, pupillary dilation, and levels of iris pigmentation. The key insight is to use the output of the segmentation phase in each assessment, which permits us to handle severely degraded samples that are likely to result of such imaging setup. Also, our experiments point that the given method improves the effectiveness of VW iris recognition, by avoiding that poor quality samples are considered in the recognition process. © 2010 IEEE. Source

Silva B.M.,University of Beira Interior
Journal of medical Internet research

Mobile Health (mHealth) proposes health care delivering anytime and anywhere. It aims to answer several emerging problems in health services, including the increasing number of chronic diseases, high costs on national health services, and the need to provide direct access to health services, regardless of time and place. mHealth systems include the use of mobile devices and apps that interact with patients and caretakers. However, mobile devices present several constraints, such as processor, energy, and storage resource limitations. The constant mobility and often-required Internet connectivity also exposes and compromises the privacy and confidentiality of health information. This paper presents a proposal, construction, performance evaluation, and validation of a data encryption solution for mobile health apps (DE4MHA), considering a novel and early-proposed cooperation strategy. The goal was to present a robust solution based on encryption algorithms that guarantee the best confidentiality, integrity, and authenticity of users health information. In this paper, we presented, explained, evaluated the performance, and discussed the cooperation mechanisms and the proposed encryption solution for mHealth apps. First, we designed and deployed the DE4MHA. Then two studies were performed: (1) study and comparison of symmetric and asymmetric encryption/decryption algorithms in an mHealth app under a cooperation environment, and (2) performance evaluation of the DE4MHA. Its performance was evaluated through a prototype using an mHealth app for obesity prevention and cares, called SapoFit. We then conducted an evaluation study of the mHealth app with cooperation mechanisms and the DE4MHA using real users and a real cooperation scenario. In 5 days, 5 different groups of 7 students selected randomly agreed to use and experiment the SapoFit app using the 7 devices available for trials. There were 35 users of SapoFit that participated in this study. The performance evaluation of the app was done using 7 real mobile devices in 5 different days. The results showed that confidentiality and protection of the users' health information was guaranteed and SapoFit users were able to use the mHealth app with satisfactory quality. Results also showed that the app with the DE4MHA presented nearly the same results as the app without the DE4MHA. The performance evaluation results considered the probability that a request was successfully answered as a function of the number of uncooperative nodes in the network. The service delivery probability decreased with the increase of uncooperative mobile nodes. Using DE4MHA, it was observed that performance presented a slightly worse result. The service average was also slightly worse but practically insignificantly different than with DE4MHA, being considered negligible. This paper proposed a data encryption solution for mobile health apps, called DE4MHA. The data encryption algorithm DE4MHA with cooperation mechanisms in mobile health allow users to safely obtain health information with the data being carried securely. These security mechanisms did not deteriorate the overall network performance and the app, maintaining similar performance levels as without the encryption. More importantly, it offers a robust and reliable increase of privacy, confidentiality, integrity, and authenticity of their health information. Although it was experimented on a specific mHealth app, SapoFit, both DE4MHA and the cooperation strategy can be deployed in other mHealth apps. Source

Diabetes mellitus is a metabolic disorder that may arise from diet habits and is growing to epidemic proportions. Young male diabetic patients present high infertility/subfertility prevalence resulting from impaired reproductive function and poor semen quality. We aimed to evaluate the effects of a high-energy diet (HED) on glucose tolerance/insulin levels and correlate the observed effects on male reproductive function with overall testicular metabolism. After 1 month, HED fed rats showed increased glycaemic levels, impaired glucose tolerance and hypoinsulinaemia. Moreover, an imbalance of intratesticular and serum testosterone levels was observed, whereas those of 17β-estradiol were not altered. High-energy diet also affected the reproductive parameters, with HED rats exhibiting a significant increase in abnormal sperm morphology. Glycolytic metabolism was favoured in testicles of HED rats with an increased expression of both glucose transporters 1 (GLUT1) and 3 (GLUT3) and the enzyme phosphofrutokinase 1. Moreover, lactate production and the expression of metabolism-associated genes and proteins involved in lactate production and transport were also enhanced by HED. Alanine testicular content was decreased and thus intratesticular lactate/alanine ratio in HED rats was increased, suggesting increased oxidative stress. Other energetic substrates such as acetate and creatine were not altered in testis from HED rats, but intratesticular glycine content was increased in those animals. Taken together, these results suggest that HED induces a pre-diabetic state that may impair reproductive function by modulating overall testicular metabolism. This is the first report on testicular metabolic features and mechanisms related with the onset of a pre-diabetic state. © 2013 American Society of Andrology and European Academy of Andrology. Source

Xisto C.M.,University of Beira Interior
International Journal for Numerical Methods in Fluids

In this paper, we propose an extension of a PISO method, previously developed to solve the Euler equations, and which is here extended to the ideal magnetohydrodynamic (MHD) equations. By following a pressure-based approach, we make use of the flexibility given by pressure equation for calculating flows at arbitrary Mach numbers. To handle MHD discontinuities, we have adapted the MHD-Advection Upstream Splitting Method for our pressure-based formulation. With the purpose of validation, four sets of test cases are presented and discussed. We start with the circularly polarized Alfvén waves that serves as a smooth flow validation. The second case is the 1-D Riemann problem that is calculated using both 1-D and 2-D formulation of the MHD equations. The third and fourth problems are the Orszag-Tang vortex and the supersonic low- β cylinder allowing validation of the method in complex 2-D MHD shock interaction. © 2013 John Wiley & Sons, Ltd. Source

Proenca H.,University of Beira Interior
IEEE Transactions on Pattern Analysis and Machine Intelligence

Iris recognition imaging constraints are receiving increasing attention. There are several proposals to develop systems that operate in the visible wavelength and in less constrained environments. These imaging conditions engender acquired noisy artifacts that lead to severely degraded images, making iris segmentation a major issue. Having observed that existing iris segmentation methods tend to fail in these challenging conditions, we present a segmentation method that can handle degraded images acquired in less constrained conditions. We offer the following contributions: 1) to consider the sclera the most easily distinguishable part of the eye in degraded images, 2) to propose a new type of feature that measures the proportion of sclera in each direction and is fundamental in segmenting the iris, and 3) to run the entire procedure in deterministically linear time in respect to the size of the image, making the procedure suitable for real-time applications. © 2010 IEEE. Source

Discover hidden collaborations