Search results for " Computer-Assisted"
showing 10 items of 1033 documents
Cardiorespiratory information dynamics during mental arithmetic and sustained attention
2015
An analysis of cardiorespiratory dynamics during mental arithmetic, which induces stress, and sustained attention was conducted using information theory. The information storage and internal information of heart rate variability (HRV) were determined respectively as the self-entropy of the tachogram, and the self-entropy of the tachogram conditioned to the knowledge of respiration. The information transfer and cross information from respiration to HRV were assessed as the transfer and cross-entropy, both measures of cardiorespiratory coupling. These information-theoretic measures identified significant nonlinearities in the cardiorespiratory time series. Additionally, it was shown that, alt…
Compensating for instantaneous signal mixing in transfer entropy analysis of neurobiological time series
2013
The transfer entropy (TE) has recently emerged as a nonlinear model-free tool, framed in information theory, to detect directed interactions in coupled processes. Unfortunately, when applied to neurobiological time series TE is biased by signal cross-talk due to volume conduction. To compensate for this bias, in this study we introduce a modified TE measure which accounts for possible instantaneous effects between the analyzed time series. The new measure, denoted as compensated TE (cTE), is tested on simulated time series reproducing conditions typical of neuroscience applications, and on real magnetoencephalographic (MEG) multi-trial data measured during a visuo-tactile cognitive experime…
Computational imaging with a balanced detector
2016
Single-pixel cameras allow to obtain images in a wide range of challenging scenarios, including broad regions of the electromagnetic spectrum and through scattering media. However, there still exist several drawbacks that single-pixel architectures must address, such as acquisition speed and imaging in the presence of ambient light. In this work we introduce balanced detection in combination with simultaneous complementary illumination in a single-pixel camera. This approach enables to acquire information even when the power of the parasite signal is higher than the signal itself. Furthermore, this novel detection scheme increases both the frame rate and the signal-to-noise ratio of the sys…
3D integral imaging display by smart pseudoscopic-to-orthoscopic conversion (SPOC).
2010
Previously, we reported a digital technique for formation of real, non-distorted, orthoscopic integral images by direct pickup. However the technique was constrained to the case of symmetric image capture and display systems. Here, we report a more general algorithm which allows the pseudoscopic to orthoscopic transformation with full control over the display parameters so that one can generate a set of synthetic elemental images that suits the characteristics of the Integral-Imaging monitor and permits control over the depth and size of the reconstructed 3D scene.
Computer assisted language learning and the internationalisation of the Portuguese language in higher education contexts
2015
The internationalisation of the Portuguese language has become a priority for academic institutions of different Portuguese-speaking countries which are trying to adapt to the current context of globalisation and ubiquitous communications through digital media. In order to achieve it, several challenges should be faced, namely providing international students with resources aimed at helping them improve their Portuguese while fostering its use in academic and scientific contexts. This can be done by identifying, creating and editing high-quality teaching materials which bear in mind the sociocultural, political, economic and linguistic contexts; using the Information and Communication Techn…
Image guidance to improve reliability and data integrity of transcranial Doppler sonography.
2012
Abstract Background Principles and accuracy of image-guided transcranial Doppler (IG TCD) sonography have been published recently. However, it remains open whether combination of image guidance and TCD offers an additional clinical advantage. This study scores the accuracy of conventional TCD examinations and investigates the potential improvement of TCD data integrity and reliability regarding the additional use of IG. Methods Conventional TCD was performed by a group of experienced investigators, who were blinded to images of a navigation system tracking the Doppler probe, whereas an independent observer documented the TCD findings, acquired by the investigators, due to saving spatial dat…
A non-parametric segmentation methodology for oral videocapillaroscopic images
2014
We aim to describe a new non-parametric methodology to support the clinician during the diagnostic process of oral videocapillaroscopy to evaluate peripheral microcirculation. Our methodology, mainly based on wavelet analysis and mathematical morphology to preprocess the images, segments them by minimizing the within-class luminosity variance of both capillaries and background. Experiments were carried out on a set of real microphotographs to validate this approach versus handmade segmentations provided by physicians. By using a leave-one-patient-out approach, we pointed out that our methodology is robust, according to precision-recall criteria (average precision and recall are equal to 0.9…
Nuadu Concept for personal management of lifestyle related health risks
2008
Majority of the health risks and diseases in the modern world are related to lifestyles, e.g., overweight, unhealthy diet, physical inactivity, sleep deprivation, and stress. Behavioral change towards healthy lifestyles is the key to the prevention and management of these risks, but early and efficient interventions are scarcely available. We present the Nuadu Concept, an ICT (Information and Communication Technologies) assisted wellness toolbox for the management of multiple, behavior-originated health risks. The concept is based on psychological models, which provide methods and motivation for behavior change. The individual is considered as the best expert of his/her own wellness. Thus, …
Multi-Path U-Net Architecture for Cell and Colony-Forming Unit Image Segmentation
2022
U-Net is the most cited and widely-used deep learning model for biomedical image segmentation. In this paper, we propose a new enhanced version of a ubiquitous U-Net architecture, which improves upon the original one in terms of generalization capabilities, while addressing several immanent shortcomings, such as constrained resolution and non-resilient receptive fields of the main pathway. Our novel multi-path architecture introduces a notion of an individual receptive field pathway, which is merged with other pathways at the bottom-most layer by concatenation and subsequent application of Layer Normalization and Spatial Dropout, which can improve generalization performance for small datase…
Analysis of the human a-wave ERG component
2006
The a-wave is one of the main issues of research in the field of ocular electrophysiology, since it is strictly connected with early photoreceptoral activities. The present study proposes mathematical methods that analyse this component in human subjects, and supports experimental evidence relating to possible correlations among the responses of photoreceptoral units under a light stimulus. The investigation is organized in two parts: the first part concerns the onset and the initial slope, up to the first minimum (about 10-15 ms), the second part deals with the main portion of the wave, up to about 30 ms. In both cases, the a-waves, recorded at various levels of luminance, have been fitted…