Au cours des examens d'Imagerie par Résonance Magnétique du cœur, l'ÉlectroCardioGramme recueilli pour la synchronisation est fortement perturbé par plusieurs artéfacts gênant la bonne détection du cycle cardiaque. Une des sources contaminantes est l'artéfact MagnétoHydroDynamique, dû aux mouvements des particules chargées du sang dans le champ magnétique. Dans ce travail, une méthode fiable pour la double synchronisation sur le rythme cardiaque et respiratoire est élaborée, permettant l'amélioration des IRM cardiaques haute résolution. Les altérations temporelles et fréquentielles des signaux ECG provoquées par l'effet MHD sont examinées. Et, dans le but de prédire le niveau de contamination dû à cet artéfact, différents modèles d'écoulements sanguins dans un champ magnétique sont étudiés. Les effets du champ sur l'écoulement sont mis en évidence, et des potentiels surfaciques susceptibles de se superposer à l'ECG sont estimés.

This master’s thesis examines how a small MIMO lighting system can be identified and controlled. Two approaches are examined and compared; the first approach is a dynamic model using state space representation, where the system identification technique is Recursive Least Square, RLS, and the controller is an LQG controller; the second approach is a static model derived from the physical properties of light and a feedback feed-forward controller consisting of a PI controller coupled with a Control Allocation, CA, technique. For the studied system, the CA-PI approach significantly outperforms the LQG-RLS approach, which leads to the conclusion that the system’s static properties are predominant compared to the dynamic properties.

<p>Eligibility for antiretroviral therapy (ART) in HIV-infected patients is defined either by a cluster of differentiation antigen 4 (CD4) count of less than 200cells/mm3 or clinical diagnosis of WHO stage III and IV. Therefore, the decision to start ART becomes difficult when CD4 cell count is not available. With limited laboratory infrastructure, the decision to start ART is usually made based on clinical symptoms leading to late commencement of ART. This calls for alternative criteria to see if nail discoloration (ND) correlates with low CD4 count among untreated HIV infected patients. This will serve as a complementary screening tool for identifying asymptomatic ARV naive HIV patients with a CD4 cell count of less than 200cells/mm3 which signifies&nbsp / severe immunosuppression. Study Design and Setting: This was a quantitative cross-sectional descriptive and analytical study involving adult ART na&iuml / ve HIV infected patients in WHO stage I and II. Systematic sampling was used to select the participants from all adult ART na&iuml / ve HIV infected patients attending APIN clinic, located at the Jos University Teaching Hospital (JUTH), Jos, Nigeria. Data Collection: Face-to-face interviews, physical examination and relevant laboratory investigations with selected participants were conducted using a questionnaire guide. Questions on socio-demographic characteristics, clinical data, general physical examinations including finger nail examination and photographing with subsequent laboratory investigations including CD4 count and western blot were employed. Data Analysis: Variables were categorized and data analyzed using descriptive statistics including the frequency, percentage frequency / mean and standard deviation of continuous variables. Association between CD4 count of &le / 200cells/mm3 and ND was tested using the chisquare test with an alpha level of 0.05. Prevalence of ND, sensitivity, specificity, positive predictive and negative predictive values and accuracy of the screening test of ND was calculated. Results: 394 patients had their fingernails photographed and assessed. It was shown that distal banded and grey nails were the common types of ND seen with a prevalence of 38%. There was an association between CD4 count &le / 200cells/mm3 and ND (p&lt / 0.0001). CD4 count &le / 200cells/mm3 was a risk factor for developing ND (RR=2.3[1.8-3.6]). The association has a sensitivity of 78%, specificity of 55%, positive predictive value of 50%, and negative predictive value of 80% and accuracy of test 63%. Conclusion: With a significant association (p&lt / 0.0001) and a sensitivity of 78%, ND can be a useful clinical indicator of immune dysfunction mediated by HIV among patients in WHO stage I or II. ND can either be a clinical sign or a symptom in HIV patients with a CD4 of &le / 200cells/mm3 as seen in the study as the specificity and sensitivity of ND compared favourably with other WHO stage III diagnosis. Recommendations: Nail discoloration should complement CD4 count as an additional staging sign to help identify patients likely to benefit from ART especially in resource-limited settings. Finally, all patients with grey or distal banded should be on co-trimoxaxole prophylaxis in line with WHO /national guideline on the use of co-trimoxaxole for all HIV positive patients with a CD4 cell count of &le / 350cells/mm3.</p>

In this thesis, the problem of multiple access interference (MAI) suppression for the multi-carrier (MC) code division multiple access (CDMA) system, based on the multi-carrier modulation with modified Gaussian wavelet, associated with the combining process is investigated for Rayleigh fading channel. The main concern of this thesis is to derive a new scheme, based on the linearly constrained constant modulus (LCCM) criterion with the robust inverse QR decomposition (IQRD) recursive least squares (RLS) algorithm to improve the performance of the wavelet-based MC-CDMA system with combining process. To verify the merits of the new algorithm, the effect due to imperfect channel parameters estimation and near-far effect are investigated. We show that the proposed robust LCCM IQRD-RLS algorithm outperforms the conventional LCCM-gradient algorithm, in terms of output SINR, for MAI suppression under channel mismatch environment. Also, the performance of the modified Gaussian wavelet-based MC-CDMA system is superior to the one with wavelet-based MC-CDMA system. It is more robust to the channel mismatch and near-far effect. Moreover, the modified Gaussian wavelet-based MC-CDMA system with robust LCCM IQRD-RLS algorithm does have better performance over other conventional approaches, such as the LCCM-gradient algorithm, maximum ratio combining (MRC), and blind adaptation algorithm, in terms of the capability of MAI suppression and bit error rate (BER).

<p>Eligibility for antiretroviral therapy (ART) in HIV-infected patients is defined either by a cluster of differentiation antigen 4 (CD4) count of less than 200cells/mm3 or clinical diagnosis of WHO stage III and IV. Therefore, the decision to start ART becomes difficult when CD4 cell count is not available. With limited laboratory infrastructure, the decision to start ART is usually made based on clinical symptoms leading to late commencement of ART. This calls for alternative criteria to see if nail discoloration (ND) correlates with low CD4 count among untreated HIV infected patients. This will serve as a complementary screening tool for identifying asymptomatic ARV naive HIV patients with a CD4 cell count of less than 200cells/mm3 which signifies&nbsp / severe immunosuppression. Study Design and Setting: This was a quantitative cross-sectional descriptive and analytical study involving adult ART na&iuml / ve HIV infected patients in WHO stage I and II. Systematic sampling was used to select the participants from all adult ART na&iuml / ve HIV infected patients attending APIN clinic, located at the Jos University Teaching Hospital (JUTH), Jos, Nigeria. Data Collection: Face-to-face interviews, physical examination and relevant laboratory investigations with selected participants were conducted using a questionnaire guide. Questions on socio-demographic characteristics, clinical data, general physical examinations including finger nail examination and photographing with subsequent laboratory investigations including CD4 count and western blot were employed. Data Analysis: Variables were categorized and data analyzed using descriptive statistics including the frequency, percentage frequency / mean and standard deviation of continuous variables. Association between CD4 count of &le / 200cells/mm3 and ND was tested using the chisquare test with an alpha level of 0.05. Prevalence of ND, sensitivity, specificity, positive predictive and negative predictive values and accuracy of the screening test of ND was calculated. Results: 394 patients had their fingernails photographed and assessed. It was shown that distal banded and grey nails were the common types of ND seen with a prevalence of 38%. There was an association between CD4 count &le / 200cells/mm3 and ND (p&lt / 0.0001). CD4 count &le / 200cells/mm3 was a risk factor for developing ND (RR=2.3[1.8-3.6]). The association has a sensitivity of 78%, specificity of 55%, positive predictive value of 50%, and negative predictive value of 80% and accuracy of test 63%. Conclusion: With a significant association (p&lt / 0.0001) and a sensitivity of 78%, ND can be a useful clinical indicator of immune dysfunction mediated by HIV among patients in WHO stage I or II. ND can either be a clinical sign or a symptom in HIV patients with a CD4 of &le / 200cells/mm3 as seen in the study as the specificity and sensitivity of ND compared favourably with other WHO stage III diagnosis. Recommendations: Nail discoloration should complement CD4 count as an additional staging sign to help identify patients likely to benefit from ART especially in resource-limited settings. Finally, all patients with grey or distal banded should be on co-trimoxaxole prophylaxis in line with WHO /national guideline on the use of co-trimoxaxole for all HIV positive patients with a CD4 cell count of &le / 350cells/mm3.</p>

Background: Stroke is a leading cause of significant physical, cognitive, and psychiatric morbidity. One risk factor for stroke is paradoxical embolization through a patent foramen ovale (PFO). In cardiac clinical practice, power M-mode Transcranial Doppler (TCD) evaluation is the gold standard for diagnosis of PFO, or right-to-left cardiac shunt (RLS). Brain micro-embolization due to diagnostic bubble contrast echocardiography may cause neurological symptoms in patients with PFO. However, the neurocognitive effects of TCD have not been studied. Objective: The purpose of this study was to evaluate cognitive outcomes in patients who undergo routine diagnostic bubble contrast TCD. The aims of the study were (1) to determine if cognitive function declines pre- to post-TCD evaluation and, (2) to assess the relationship between cognitive function and severity of the RLS measured using the Spencer Grading System. Methods: One hundred and four participants referred to Sorensen Cardiovascular Group for diagnosis of RLS were evaluated for changes in cognitive functioning at three time points. A dual baseline (pre-test and baseline test) was administered to mitigate practice effects between the first and second administrations. All pre and post-TCD comparisons were analyzed using the baseline test and post-TCD test, controlling for the effects of practice, if present. Results: Practice effects were observed for the working memory task, with significant improvement in working memory scores occurring between the first (pre-test) and second (baseline) administrations. The main effect for shunt group (no shunt vs. moderate-to-severe shunt) and the shunt group by time interactions were not significant for processing speed, attention, or working memory, adjusting for practice effects, age, and education. Migraine did not predict group status for mood or shunt variables. Conclusion: Cardiac patients with both small and large RLS did not experience a decline in processing speed, attention, or working memory ability following TCD, suggesting that TCD-induced microemboli do not result in immediate cognitive deficits in these domains. These findings support the use of TCD for routine evaluation of PFO, even in patients with severe RLS, although findings are limited to young (30s), medically healthy, predominately Caucasian individuals assessed immediately following TCD. Results do not exclude the possibility of cognitive impairment at follow-up, on other cognitive tests, or in other cognitive domains.

Dentro del marco de los sistemas de comunicaciones de banda ancha podemos encontrar canales modelados como sistemas MIMO (Multiple Input Multiple Output) en el que se utilizan varias antenas en el transmisor (entradas) y varias antenas en el receptor (salidas), o bien sistemas de un solo canal que puede ser modelado como los anteriores (sistemas multi-portadora o multicanal con interferencia entre ellas, sistemas multi-usuario con una o varias antenas por terminal móvil y sistemas de comunicaciones ópticas sobre fibra multimodo). Estos sistemas pretenden alcanzar valores de capacidad de transmisión relativa al ancho de banda muy superiores al de un único canal SISO (Single Input Single Output). Hoy en dÍa, existe, desde un punto de vista de implementación del sistema, una gran actividad investigadora dedicada al desarrollo de algoritmos de codificación, ecualización y detección, muchos de ellos de gran complejidad, que ayuden a aproximarse a las capacidades prometidas. En el aspecto relativo a la detección, las soluciones actuales se pueden clasificar en tres tipos: soluciones subóptimas, ML (Maximum Likelihood) o cuasi-ML e iterativas. En estas ultimas, se hace uso explicito de técnicas de control de errores empleando intercambio de información soft o indecisa entre el detector y el decodificador; en las soluciones ML o cuasi-ML se lleva a cabo una búsqueda en árbol que puede ser optimizada llegando a alcanzar complejidades polinómicas en cierto margen de relación señal-ruido; por ultimo dentro de las soluciones subóptimas destacan las técnicas de forzado de ceros, error cuadrático medio y cancelación sucesiva de interferencias SIC (Succesive Interference Cancellation), esta última con una versión ordenada -OSIC-. Las soluciones subóptimas, aunque no llegan al rendimiento de las ML o cuasi-ML son capaces de proporcionar la solución en tiempo polinómico de manera determinista. En la presente tesis doctoral, hemos implementado un método basado en la literatura para l / Martínez Zaldívar, FJ. (2007). Algoritmos paralelos segmentados para los problemas de mínimos cuadrados recursivos (RLS) y de detección por cancelación ordenada y sucesiva de interferencia (OSIC) [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1873

No description available.

<div> <div> <div> <p>Speech quality is a demand in voice commanded systems and in telephony. The voice communication system in real time often suffers from audible echoes. In order to cancel echoes, an acoustic echo cancellation system is designed and applied to increase speech quality both subjectively and objectively. </p> <p>In this research we develop various nonlinear adaptive filters wielding the new channel sparsity-aware recursive least squares (RLS) algorithms using a sequential update. The developed nonlinear adaptive filters using the sparse sequential RLS (S-SEQ-RLS) algorithm apply a discard function to disregard the coefficients which are not significant or close to zero in the weight vector for each channel in order to reduce the computational load and improve the algorithm convergence rate. The channel sparsity-aware algorithm is first derived for nonlinear system modeling or system identification, and then modified for application of echo cancellation. Simulation results demonstrate that by selecting a proper threshold value in the discard function, the proposed nonlinear adaptive filters using the RLS (S-SEQ-RLS) algorithm can achieve the similar performance as the nonlinear filters using the sequential RLS (SEQ-RLS) algorithm in which the channel weight vectors are sequentially updated. Furthermore, the proposed channel sparsity-aware RLS algorithms require a lower computational load in comparison with the non-sequential and non-sparsity algorithms. The computational load for the sparse algorithms can further be reduced by using data-selective strategies. </p> </div> </div> </div>

No description available.