994 resultados para RF signal loss


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The Electromyography (EMG) is an important tool for gait analyzes and disorders diagnoses. Traditional methods involve equipment that can disturb the analyses, being gradually substituted by different approaches, like wearable and wireless systems. The cable replacement for autonomous systems demands for technologies capable of meeting the power constraints. This work presents the development of an EMG and kinematic data capture wireless module, designed taking into account power consumption issues. This module captures and converts the analog myoeletric signal to digital, synchronously with the capture of kinetic information. Both data are time multiplexed and sent to a PC via Bluetooth link. The work carried out comprised the development of the hardware, the firmware and a graphical interface running in an external PC. The hardware was developed using the PIC18F14K22, a low power family of microcontrollers. The link was established via Bluetooth, a protocol designed for low power communication. An application was also developed to recover and trace the signal to a Graphic User Interface (GUI), coordinating the message exchange with the firmware. Results were obtained which allowed validating the conceived system in static and with the subject performing short movements. Although it was not possible to perform the tests within more dynamic movements, it is shown that it is possible to capture, transmit and display the captured data as expected. Some suggestions to improve the system performance also were made.

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In cases of extensive damage to the foot, with significant bone loss, it is generally accepted that reconstruction must include bone flaps or grafts either in the emergency setting or subsequently. In this report, we describe the case of an 18-year-old student with an avulsion injury of the dorsum of his right foot. Consequently, he lost most of the soft tissue over the dorsum of the foot and the cuboid, navicular, and cuneiform bones. A latissimus dorsi free flap was used to reconstruct the defect. A functional pseudoarthrosis developed between the remaining bones of the foot, and the patient experienced satisfactory foot function after rehabilitation. For this reason, no additional reconstructive procedure was undertaken. This case suggests that it might be adequate to use the latissimus dorsi muscle flap more liberally than previously reported in the reconstruction of extensive defects of the dorsum of the foot, including cases with significant bone loss. This option could avoid the morbidity and inconvenience of a second surgery and the need to harvest a bone flap or graft.

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In this paper we study several natural and man-made complex phenomena in the perspective of dynamical systems. For each class of phenomena, the system outputs are time-series records obtained in identical conditions. The time-series are viewed as manifestations of the system behavior and are processed for analyzing the system dynamics. First, we use the Fourier transform to process the data and we approximate the amplitude spectra by means of power law functions. We interpret the power law parameters as a phenomenological signature of the system dynamics. Second, we adopt the techniques of non-hierarchical clustering and multidimensional scaling to visualize hidden relationships between the complex phenomena. Third, we propose a vector field based analogy to interpret the patterns unveiled by the PL parameters.

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Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica

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Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica

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Dissertação para obtenção do Grau de Mestre em Engenharia Física

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The use of multiparametric magnetic resonance imaging (mp-MRI) for prostate cancer has increased over recent years, mainly for detection, staging, and active surveillance. However, suspicion of recurrence in the set of biochemical failure is becoming a significant reason for clinicians to request mp-MRI. Radiologists should be able to recognize the normal post-treatment MRI findings. Fibrosis and atrophic remnant seminal vesicles after prostatectomy are often found and must be differentiated from local relapse. Moreover, brachytherapy, external beam radiotherapy, cryosurgery, and hormonal therapy tend to diffusely decrease the signal intensity of the peripheral zone on T2-weighted images (T2WI) due to the loss of water content, consequently mimicking tumor and hemorrhage. The combination of T2WI and functional studies like diffusion-weighted imaging and dynamic contrast-enhanced improves the identification of local relapse. Tumor recurrence tends to restrict on diffusion images and avidly enhances after contrast administration either within or outside the gland. The authors provide a pictorial review of the normal findings and the signs of local tumor relapse after radical prostatectomy, external beam radiotherapy, brachytherapy, cryosurgery, and hormonal therapy.

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OBJECTIVE: To determine the prevalence of fibroblast growth factor receptor 1 (FGFR1) mutations and their predicted functional consequences in patients with idiopathic hypogonadotropic hypogonadism (IHH). DESIGN: Cross-sectional study. SETTING: Multicentric. PATIENT(S): Fifty unrelated patients with IHH (21 with Kallmann syndrome and 29 with normosmic IHH). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Patients were screened for mutations in FGFR1. The functional consequences of mutations were predicted by in silico structural and conservation analysis. RESULT(S): Heterozygous FGFR1 mutations were identified in six (12%) kindreds. These consisted of frameshift mutations (p.Pro33-Alafs*17 and p.Tyr654*) and missense mutations in the signal peptide (p.Trp4Cys), in the D1 extracellular domain (p.Ser96Cys) and in the cytoplasmic tyrosine kinase domain (p.Met719Val). A missense mutation was identified in the alternatively spliced exon 8A (p.Ala353Thr) that exclusively affects the D3 extracellular domain of FGFR1 isoform IIIb. Structure-based and sequence-based prediction methods and the absence of these variants in 200 normal controls were all consistent with a critical role for the mutations in the activity of the receptor. Oligogenic inheritance (FGFR1/CHD7/PROKR2) was found in one patient. CONCLUSION(S): Two FGFR1 isoforms, IIIb and IIIc, result from alternative splicing of exons 8A and 8B, respectively. Loss-of-function of isoform IIIc is a cause of IHH, whereas isoform IIIb is thought to be redundant. Ours is the first report of normosmic IHH associated with a mutation in the alternatively spliced exon 8A and suggests that this disorder can be caused by defects in either of the two alternatively spliced FGFR1 isoforms.

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OBJECTIVE: To assess the spectrum and prevalence of mutations in the GJB2 gene in Portuguese nonsyndromic sensorineural hearing loss (NSSHL) patients. DESIGN: Sequencing of the coding region, basal promoter, exon 1, and donor splice site of the GJB2 gene; screening for the presence of the two common GJB6 deletions. STUDY SAMPLE: A cohort of 264 Portuguese NSSHL patients. RESULTS: At least one out of 21 different GJB2 variants was identified in 80 (30.2%) of the 264 patients analysed. Two mutant alleles were found in 53 (20%) of these probands, of which 83% (44/53) harboured at least one c.35delG allele. Twenty-seven (10.2%) of the probands harboured only one mutant allele. Subsequent analysis revealed that the GJB6 deletion del(GJB6-D13S1854) was present in at least 7.4% (2/27) of the patients carrying only one mutant GJB2 allele. Overall, one in five (55/264) of the patients were diagnosed as having DFNB1-related NSSHL, of which the vast majority (53/55) harboured only GJB2 mutations. CONCLUSIONS: This study provides clear demonstration that mutations in the GJB2 gene are an important cause of NSSHL in Portugal, thus representing a valuable indicator as regards therapeutical and rehabilitation options, as well as genetic counseling of these patients and their families.

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Dissertação apresentada para obtenção do Grau de Doutor em Biologia, na especialidade de Genética Molecular, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

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Dissertação apresentada para obtenção do Grau de Mestre em Engenharia Electrotécnica e de Computadores, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

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RESUMO: A surdez súbita (SS) caracteriza-se por uma perda abrupta de audição, mais frequentemente unilateral e associada a sensação de preenchimento aural, acufenos e vertigem. Afecta 5-20/100.000pessoas/ano (sobretudo adultos em fase activa na década de 40), com grande impacto na qualidade de vida. Possíveis causas incluem doenças infecciosas, circulatórias, traumáticas, imunológicas, neoplásicas, neurológicas, tóxicas e cocleares. No entanto, a causa da SS permanece desconhecida na maioria dos casos (80%), o que origina tratamentos controversos e frequentemente ineficientes. Os tratamentos disponíveis variam desde corticosteróides a antivirais, vasodilatadores, anti-agregantes, anticoagulantes, vitaminas e oxigénio hiperbárico (OHB). Atendendo a falta de informação relativa à etiologia e fisiopatologia da SS, pretendemos avaliar a evolução clínica dos doentes com SS tratados com OHB no Centro de Medicina Subaquática e Hiperbárica (CMSH) de Lisboa entre 2000 e 2005, durante um período mínimo de 5 anos, na tentativa de identificar eventuais factores de risco ou noxas clínicas com a SS. O estudo retrospectivo proposto baseia-se na revisão de processos clínicos do CMSH e na aplicação telefónica de questionários médicos de “follow-up” confidenciais – tanto a doentes (grupo de estudo), como aos respectivos esposos/companheiros/membros próximos da família (grupo de controlo) –, com particular ênfase nos antecedentes médicos e história clínica actual. Um estudo preliminar de 20 pessoas (10 doentes e 10 controlos) foi efectuado para antecipar dificuldades e estimar as necessidades logísticas. As dificuldades identificadas foram: 1) selecção dos doentes com números de telefone válidos e processos clínicos completos (com audiograma inicial e final); 2) contacto telefónico com os participantes de ambos os grupos (de estudo e controlo); 3) recursos humanos requeridos. Dado que a SS não é uma doença em si, mas um sintoma de uma doença subjacente, acreditamos que este estudo epidemiológico seja importante e útil, capaz de gerar novas luzes sobre a fisiopatologia e mecanismos desta entidade clínica.-------------ABSTRACT:Sudden sensorineural hearing loss (SSHL) is characterized by abrupt, mostly unilateral loss of hearing, frequently associated to aural fullness, tinnitus and vertigo. It affects 5-20/100.000 people/year (particularly working adults in the 40ths), with huge impact on quality of life. Possible causes include infectious, circulatory, traumatic, immunologic, metabolic, neoplastic, neurologic, toxic and unidentified cochlear diseases. Nevertheless, SSHL’s etiology remains unknown in most cases (80%), giving rise to controversial (and frequently ineffective) treatments. Available therapies range from corticosteroids to antivirals, vasodilators, antiaggregants, anticoagulants, vitamins and hyperbaric oxygen (HBO). Given the lack of data concerning SSHL’s etiology and physiopathology, we intend to evaluate clinical evolution of such patients treated with HBO in the Underwater and Hyperbaric Medical Center (UHMC) at Lisbon from 2000 to 2005 during a minimum period of 5 years, in an attempt to identify eventual risk factors or clinical associations to SSHL. The intended retrospective study is based on the review of patients’ medical charts from UHMC and confidential follow-up questionnaires applied telephonically both to patients (study group) and patients’ spouse/partner/close family member (control group), focusing past and present medical history. A preliminary study of 20 subjects (10 of each group) was performed to anticipate difficulties and to estimate the required logistics. The identified difficulties were: 1) selection of subjects with valid phone numbers and complete medical charts (with initial and final audiograms); 2) telephonic contact with subjects from the study and control group; 3) human logistics required. As it is believed that SSHL is not a disease by itself but rather a symptom of an underlying disease, we believe that this epidemiologic study is important and will hopefully generate sound scientific knowledge concerning physiopathology and mechanism of disease of SSHL.

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Dissertação para obtenção do Grau de Mestre em Engenharia Eletrotécnica e de Computadores, pela Universidade Nova de Ciências e Tecnologia

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Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica

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A young male developed hearing loss, vertigo, headache and facial palsy. Neurological examination did not show any abnormalities. Two years later, cervical lymphadenopathy, hepatosplenomegaly and atypical lymphocytes in peripheral blood revealed leukemia. At the same time, acquired ichthyosis was observed. Subsequently, neurological abnormalities revealed myelopathy associated with HTLV-1, due to vertical transmission.