Examinando por Autor "Arboleda-Clavijo, C. (Carolina)"

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    Control de mouse para computador mediante potenciales eléctricos oculares
    (2014-04-20) Arboleda-Clavijo, C. (Carolina); García-Cossio, E. (Eliana); Palacio-Ochoa, M. (Marcela)
    The use of computers and associated technology, has promoted the development of more comfortable and efficient hardware devices. Many handicapped people can not access to this technology. As a result, innovative mechanisms have been designed to attend the requirements of these people. One of such mechanisms has been the control through biopotentials. This article presents the construction of a mouse prototype, which allows horizontal displacements in response to left and right ocular movements that are registered by instrumentation amplifiers, processed and microcontrolled.
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    Diseño y construcción de un prototipo de interfaz cerebro-computador para facilitar la comunicación de personas con discapacidad motora
    (2013-11-27) Arboleda-Clavijo, C. (Carolina); García-Cossio, E. (Eliana); Posada, A. (Alejandro); Torres-Villa, R. A. (Róbinson Alberto)
    A brain-computer interface (BCI) is a communication system that translates a brain signal (e.g. sensorimotor rhythms, evoked potentials) into a control signal and, therefore, constitutes an innovative communication alternative for people with severe motor disability (such as patients with amyotrophic lateral sclerosis). This project proposes the development of a BCI prototype based on the recording of P300 cognitive potentials using electroencephalography. The prototype uses a six-channel electroencephalograph to acquire the signals, and through a visual stimulation matrix containing the letters of the alphabet and icons associated to each one gives the user the possibility of writing words or elaborating messages with the icons. To process the signals (filtering and decimation, among other methods), the software BCI2000 and MATLAB 7.0 were used. The latter was used to program three different linear translation algorithms (linear discriminant analysis, least squares analysis and stepwise linear discriminant analysis), in order to translate the recorded evoked potentials into communication signals.
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    Image-quality optimization for dual energy computed tomography (DECT) three-material decomposition
    (2014-04-23) Arboleda-Clavijo, C. (Carolina); Pelc, N. (Norbert)
    Dual energy computed tomography, which consists of the acquisition of two images of a given region of interest using two different x-ray energies, has been used to decompose images. For example, it has been proposed to estimate the degree of stenosis of blood vessels with calcifi ed plaques. Pragmatic realities, though, such as beam hardening, scattered radiation and mostly quantum noise, reduce the ideal of a perfect decomposition. In this study, a dual energy separation method for iodinated contrast media, cortical bone and soft tissue was implemented; afterwards, it was tested in simulated noiseless and noisy situations. The noise propagation was modeled mathematically, and an image-quality optimization technique regarding the right distribution of radiation dose between the high and low energy images was proposed. The results obtained suggest that in the absence of noise and using mono-energetic beams, an accurate separation is possible, but when noise is added and poly-chromatic spectra used this decomposition becomes more challenging.
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    Tomografía computarizada por rayos X: fundamentos y actualidad
    (2014-04-23) Ramírez-Giraldo, J. C. (Juan Carlos); Arboleda-Clavijo, C. (Carolina); McCollough, C. (Cynthia)
    This paper reviews the fundamentals of x-ray computed tomography. It starts by summarizing the early days of the technique and its evolution through time, as well as the physical principles of x-ray production. Subsequently, the mathematical principles of image reconstruction are discussed with emphasis in both analytical and iterative reconstruction methods. A complete section is dedicated to review the main concepts related with the risks of ionizing radiation, and discuss some of the most recent controversies about CT radiation and how those risks affect scanning protocols. Finally, based on the most recent advances and trends in CT, the paper discuss about those areas, which, presumably, will be the research focus of CT in the near future.