Cooperative diversity schemes for wireless communication systems

Mestrado em Engenharia Electrónica e TelecomunicaçõesA presente dissertação insere-se na área das comunicações sem fios, ou mais especificamente na temática da diversidade cooperativa. Neste trabalho é feito o estudo, implementação e avaliação do desempenho de esquemas de diversidade cooperativa de baixa complexidade para sistemas de comunicação móvel. Estes esquemas são mapeados em modelos de simulação baseados em OFDMA e são completamente simulados em CoCentric System Studio. Os resultados obtidos com os modelos desenvolvidos mostram que os esquemas de diversidade cooperativa atenuam os efeitos do desvanecimento induzido pela propagação multipercurso, aumentando desta forma a capacidade e cobertura dos sistemas wireless. Os ganhos são particularmente altos quando as perdas de percurso são consideráveis, como é o caso das zonas urbanas densas. ABSTRACT: This dissertation is inserted into the wireless communication, or more specifically, into the cooperative diversity field. within this thesis, the performance of low-complexity cooperative diversity schemes projected for mobile communication systems are studied, implemented and evaluated. These schemes are mapped into simulation models based on OFDMA and are fully simulated in the CoCentric System Studio environment. The obtained results show that the proposed cooperative schemes for the uplink communication mitigate fading induced by multipath propagation, thereby increasing the capacity and coverage of wireless systems. Cooperation gains are particularly high when multipath losses are considerable, as is the case for dense urban regions

Partial scanning techniques to assess body composition in broad individuals using DXA : a validation study for Hologic Explorer-W densitometers

Mestrado em Exercício e SaúdeBackground/Objectivos: A densitometria radiológica de dupla energia (DXA) é uma técnica standard para avaliação da composição corporal a nível de corpo inteiro com uma limitação identificada: as dimensões da área de scan dos densitómetros impedem a sua utilização em indivíduos largos. Apesar da largura dos equipamentos ter sido estendida em versões recentes, os mesmos ainda não estão disponíveis na maioria dos laboratórios e clínicas. Reconhece-se por isso pertinência no desenvolvimento de abordagens que solucionem esta limitação metodológica nos densitómetros existentes, sendo o objectivo do presente estudo a validação e comparação de técnicas de scanning parcial para avaliação da composição corporal de indivíduos largos e em densitómetros QDR Explorer-W. Sujeitos/Métodos: A amostra consistiu em 198 sujeitos (27.8 10.1 anos; 61% mulheres), incluindo atletas e não-atletas com peso normal, excesso de peso e obesidade (índice de massa corporal, IMC: 17.0 – 40.1 kg/m2). Cada sujeito foi sujeito a uma avaliação de corpo inteiro num densitómetro Hologic Explorer-W (fan-beam) de acordo com procedimentos estandardizados. Os scans de corpo inteiro foram analisados para obter as estimativas de referência, e foram novamente analisados para obter estimativas para três técnicas de scanning parcial: RSU) assume-se que o membro superior esquerdo é igual ao direito; RSUL) os membros superior e inferior esquerdos são considerados iguais aos direitos; HS) assume-se que a totalidade do lado esquerdo, seccionado pelo plano sagital, é igual ao lado direito. As variáveis de interesse do estudo foram conteúdo mineral ósseo (CMO), massa isenta de gordura e osso (MIGO) e massa gorda (MG, %MG). Para cada uma destas, efectuou-se uma abordagem validativa contemplando comparação de médias de grupos, regressão linear e análise de concordância, incluindo o coeficiente de concordância da correlação (CCC) . Resultados: RSU foi a técnica com melhor desempenho. As estimativas para CMO, MIGO, MG e %MG por RSU foram significativamente diferentes dos valores de referência, ainda as diferenças tenham sido pequenas (0.010 kg, 0.172 kg, -0.026 kg e -0.10% para CMO, MIGO, MG e %MG respectivamente). As técnicas alternativas explicaram > 99% da variância dos scans de referência, com baixos limites de concordância (RSU: -0.010 to 0.031 kg, -0.109 to 0.453 kg, -0.219 to 0.167 kg e – 0.35 to 0.15% para CMO, MIGO, MG e %MG respectivamente). Os CCCs foram > 0.99 para todos os compartimentos e %FM. Conclusão: Independentemente do IMC, tipo de prática desportiva e género, a técnicas de scanning parcial são soluções válidas e simples para avaliar indivíduos largos em densitómetros QDR Explorer-W. RSU é a opção recomendada, seguida por RSUL. No entanto, os erros individuais para BMC e MIGO poderão ser superiores em praticantes de desportos pautados pelo uso preferencial de membros dominantes.ABSTRACT: Background/Objectives: Dual-energy X-ray absorptiometry (DXA) is a standard technique for whole-body composition analysis with a known limitation: the table dimensions of DXA scanners prohibit the assessment of broad individuals. Newer DXA instruments have an extended active scan area, but these devices are still unavailable in most research facilities and clinics. To solve this methodological gap in the existing equipment, the aim of this study was to validate and compare partial scanning techniques to assess whole-body composition of broad individuals in Hologic Explorer-W densitometers. Subjects/Methods: The sample consisted of 198 participants (27.8 10.1 yrs; 61% women), including normal weight, overweight and obese non-athletes and athletes (body mass index, BMI: 17.0 – 40.1 kg/m2). A single scan was performed in an Hologic Explorer-W fan-beam densitometer in each participant according to standard procedures. The whole-body scan was analyzed to obtain estimates for the reference procedure. The same scan was reanalyzed to obtain estimates for three partial scanning techniques: RSU) the left upper limb is set equal to the right side limb; RSUL) the left upper and lower limbs are set equal to the right side; HS) an half-scan is taken from the right side of the body and the contralateral side is set equal to it. Bone mineral content (BMC), lean soft tissue (LST) and fat mass (FM, %FM) were considered. Multiple regression analysis, mean group comparison, linear regression and agreement analysis, including the inspection of the concordance coe cient of correlation (CCC), were performed for the BMC, LST, FM and %FM compartments. Results: RSU was the best performing strategy of this study. The estimates for BMC, LST, FM and %FM from RSU were significantly di erent from those of the reference whole-body scans, though di erences were small (0.010 kg, 0.172 kg, -0.026 kg and -0.10% for BMC, LST, FM and %FM, respectively). The alternative procedures explained more than 99% of the variance of the reference scan with low limits of agreement (RSU: -0.010 to 0.031 kg, -0.109 to 0.453 kg, -0.219 to 0.167 kg, and – 0.35 to 0.15% for BMC, LST, FM and %FM, respectively). The CCCs were greater than 0.99 for all compartments. Conclusions: Regardless of BMI, athletic status and gender, partial scanning techniques are valid and simple solutions to be used in individuals broader than the DXA scan area. RSU is the recommended technique, followed by RSU. However, individual errors for BMC and LST may be higher in athletes engaged in lateral dominant sports practice

Single and multiple antenna relay-assisted techniques for uplink and downlink OFDM systems

In this paper we propose and assess the performance of relay-assisted schemes designed for both the uplink and downlink OFDM based systems, using efficient distributed space-frequency block coding protocols. We consider the use of an antenna array at the base station and a single antenna at the user terminal. At the relay node we consider either single antenna or an antenna array. We assume that some of the user terminals deployed in a certain area could act as relaying-able terminals for the communication of other users. Two types of relay-assisted protocols are considered: equalize-and-forward and decode-and-forward. The optimal maximum ratio combining coefficients are derived for the proposed relay-assisted schemes. The performance of these cooperative schemes is evaluated under realistic scenarios, considering typical pedestrian scenarios based on WiMAX specifications and using channel convolutional turbo code. The proposed schemes are also compared against the non-cooperative OFDM based systems. +umerical results show that the availability of antenna arrays at the relays significantly improves the cooperative systems performance, which outperform the non-cooperative ones in most studied scenarios

Dietary acid load and relationship with albuminuria and glomerular filtration rate in individuals with chronic kidney disease at predialysis state

The Western diet, characterized by excessive consumption of animal protein and reduced intake of vegetables and fruits, is also rich in sulfur, chlorine, and organic acids, which are the main sources of dietary acid load. A relationship between dietary acid load, renal function, and progression of chronic kidney disease has been demonstrated. Dietary modifications seem to contribute to a reduction in dietary acid load and are associated with improved outcomes in individuals with chronic kidney disease (CKD). The aim of this paper was to review the existing evidence concerning the association between dietary acid load and renal function in non-dialyzed individuals with CKD. A systematic review was conducted by gathering articles in electronic databases (MEDLINE/PubMed, Scopus, and Web of Science) from January 2018 to May 2021. Dietary acid load and GFR and/or albuminuria were analyzed. A total of 1078 articles were extracted, of which 5 met the inclusion criteria. Only one study found no statistically significant associations between the study variables. The remaining showed a negative association between dietary acid load and renal function. This systematic review confirmed the existence of an association between dietary acid load and renal function, with a high dietary acid load contributing to a decreased renal function.info:eu-repo/semantics/publishedVersio

Pulse oximetry based on photoplethysmography imaging with red and green light: calibratability and challenges

Remotely measuring the arterial blood oxygen saturation (SpO 2) in visible light (Vis) involves different probing depths, which may compromise calibratibility. This paper assesses the feasibility of calibrating camera-based SpO 2 (SpO 2,cam) using red and green light. Camera-based photoplethysmographic (PPG) signals were measured at 46 healthy adults at center wavelengths of 580 nm (green), 675 nm (red), and 840 nm (near-infrared; NIR). Subjects had their faces recorded during normoxia and hypoxia and under gradual cooling. SpO 2,cam estimates in Vis were based on the normalized ratio of camera-based PPG amplitudes in red over green light (RoG). SpO 2,cam in Vis was validated against contact SpO 2 (reference) and compared with SpO 2,cam estimated using red-NIR wavelengths. An RoG-based calibration curve for SpO 2 was determined based on data with a SpO 2 range of 85-100%. We found an [Formula: see text] error of 2.9% (higher than the [Formula: see text] for SpO 2,cam in red-NIR). Additional measurements on normoxic subjects under temperature cooling (from [Formula: see text] to [Formula: see text]) evidenced a significant bias of - 1.7, CI [- 2.7, - 0.7]%. It was also noted that SpO[Formula: see text] estimated at the cheeks was significantly biased (- 3.6, CI [- 5.7, - 1.5]%) with respect to forehead estimations. Under controlled conditions, SpO[Formula: see text] can be calibrated with red and green light but the accuracy is less than that of SpO[Formula: see text] estimated in the usual red-NIR window

Atitudes dos alunos do ensino básico acerca da paralisia cerebral: uma intervenção escolar através de um vídeo para aumentar o conhecimento e diminuir o estigma

Dissertação de mestrado em Psicologia AplicadaCurrently, the majority of children with disabilities attend mainstream schools. Thus, it seems important to develop interventions with children without impairments to raise their awareness about the importance of including children with disabilities, such as children with Cerebral Palsy. This investigation aims to assess the efficacy of a short-training on Cerebral Palsy to increase knowledge and decrease stigma towards individuals with this condition in mainstream elementary school students. Thirty-five classes of the 4th and 5th grades were recruited, making a total of 638 students. The pre-test took place one week before the videobased intervention and the post-test immediately after the visualization of the video. This video was designed to transmit declarative knowledge about Cerebral Palsy and some suggestions on how to interact with children with this condition. The results show that social distance scores towards people with Cerebral Palsy decreased and attitudes become more positive. The results also showed that children who know people with Cerebral Palsy had lower levels of social distance compared with children who do not know people with Cerebral Palsy. These results indicate that interventions of this type are effective and a useful tool to help integrate children with disabilities into mainstream schools.Atualmente, a maioria das crianças com deficiência frequentam escolas regulares. Desta forma, parece importante desenvolver intervenções junto de crianças sem deficiência para aumentar a conscientização sobre a inclusão de crianças com deficiência, como crianças com Paralisia Cerebral. A presente investigação tem como objetivo avaliar a eficácia de uma intervenção de curta duração para aumentar o conhecimento e diminuir o estigma em relação a indivíduos com Paralisia Cerebral, em estudantes do ensino básico regular. Foram recrutadas 35 turmas dos 4.º e 5.º anos, perfazendo um total de 638 alunos. Os momentos de avaliação decorreram uma semana antes da visualização de um vídeo e imediatamente após a visualização do mesmo, que pretendia transmitir conhecimento declarativo sobre a Paralisia Cerebral e formas de interagir com crianças com esta problemática. Os resultados indicaram que os valores da distância social em relação à Paralisia Cerebral diminuíram e as atitudes tornaram-se mais positivas. Os resultados indicaram também que crianças que conheciam pessoas com Paralisia Cerebral apresentam níveis de distância social mais baixos do que crianças que não conhecem pessoas com esta condição. Estes resultados indicam que intervenções deste tipo são eficazes e constituem uma ótima ferramenta para ajudar na integração de crianças com deficiências nas escolas

Relacionamento do casal no âmbito da sexualidade na mulher submetida a histerectomia

Enquadramento: A investigação do impacto da histerectomia na vida sexual da mulher ainda não é conclusiva, havendo evidências que apontam para o facto da remoção do útero poder ter efeitos adversos no funcionamento sexual feminino, em decorrência das alterações anatómicas pélvicas e a consequentes alterações psicológicas. Objetivos: Verificar que variáveis sociodemográficas e profissionais interferem no relacionamento do casal no âmbito da sexualidade na mulher com histerectomia; averiguar se as variáveis de saúde sexual e reprodutiva interferem no relacionamento do casal no âmbito da sexualidade na mulher com histerectomia; identificar que variáveis clínicas interferem no relacionamento do casal no âmbito da sexualidade na mulher com histerectomia; averiguar se as variáveis contextuais à sexualidade interferem no relacionamento do casal no âmbito da sexualidade na mulher com histerectomia; verificar se existe relação entre a qualidade de vida e o relacionamento do casal no âmbito da sexualidade na mulher com histerectomia. Métodos: Estudo quantitativo, transversal e descritivo-correlacional. A amostra é não probabilística por conveniência, composta por de 129 mulheres, média de idade de 55,82 anos (±3,97 anos) submetidas a histerectomia, a frequentar a consulta de ginecologia de um hospital da zona centro do país. Como instrumento de recolha de dados utilizou-se um questionário que permitiu fazer a caracterização sociodemográfica, socioprofissional, de saúde sexual e reprodutiva, clínica e contextos da sexualidade. Foi incluída ainda a Escala WHOQOL-BREF (Grupo WHOQOL, 1998, Barros, 2002) e o Inventário de Satisfação Sexual – versão feminina (GRISS: Rust & Golombok, 1986), traduzida e adaptada para a população portuguesa por Sandra Vilarinho e Pedro Nobre (2006). Resultados: Constata-se que 50,4% das mulheres não sofreu alteração da vivência da sexualidade após a histerectomia, contrariamente a 49,6% que referiram como motivos a diminuição do interesse sexual (37,2%), a diminuição da autoestima (9,3%) e a presença de dor (2,3%). Na globalidade, as mulheres revelam satisfação sexual (média=40,457.81). Quanto à perceção como mulheres (considerarem sentir-se mais ou menos femininas) após a histerectomia, a maioria das mulheres considera que permaneceu igual (56,6%). Em relação à qualidade de vida, o valor médio mais elevado corresponde ao domínio das relações sociais (média=69,259,70), seguindo-se o domínio ambiente (média=67,7812,31). O motivo da histerectomia, as complicações cirúrgicas no hospital e a consulta de vigilância após a histerectomia foram variáveis com relevância estatisticamente significativa. As mulheres que revelam mais satisfação sexual são as que o motivo da histerectomia foi a patologia ginecológica benigna (p= 0,000), sem complicações cirúrgicas no hospital (p=0,004), bem como as que referem ter consulta de vigilância após a histerectomia (p=0,001). Quanto à relação entre a satisfação sexual e a perceção como mulher (considerar sentir-se mais ou menos feminina) após a histerectomia, as mulheres que manifestam mais satisfação sexual são as que consideram que a sua perceção como mulher após a histerectomia melhorou (OM=48,67) e as que referem ter piorado revelam-se menos satisfeitas sexualmente (OM=82,76; (X2=11,703; p=0,003). As variáveis preditoras da satisfação sexual são a idade, a qualidade de vida global e as dimensões da qualidade de vida. Apurou-se que os domínios físico, psicológico e ambiente da qualidade de vida estabelecem uma relação inversa e a idade, a qualidade de vida global e o domínio das relações sociais uma relação direta com a satisfação sexual, sugerindo que as mulheres com mais idade, melhor perceção da qualidade de vida global, melhor perceção da qualidade de vida no domínio das relações sociais revelam maior satisfação sexual pela inexistência de um relacionamento problemático. Conclusões: Os resultados encontrados assumem-se como importantes para a futura prática profissional, no âmbito da Enfermagem de Saúde Materna, Obstétrica e Ginecologia, servindo de base para a intervenção em mulheres antes e após a histerectomia, que requerem um cuidado humanizado e holístico, sem que se possa descurar qualquer uma das suas dimensões, física, psicológica, sexual, social e familiar. Palavras-chave: Histerectomia, Sexualidade, Relacionamento do casal.Abstract Background: Research into the impact of hysterectomy on women's sexual life is not yet conclusive, and evidence points to the fact that removal of the uterus may have adverse effects on female sexual functioning due to pelvic anatomical changes and consequent psychological changes. Objectives: To verify that sociodemographic and professional variables interfere in the couple's relationship in the context of sexuality in women with hysterectomy; to ascertain whether the sexual and reproductive health variables interfere with the couple's relationship in the context of sexuality in women with hysterectomy; identify which clinical variables interfere with the couple's relationship in the context of sexuality in women with hysterectomy; to investigate if the contextual variables to sexuality interfere in the couple's relationship in the context of sexuality in women with hysterectomy; to verify if there is a relationship between the quality of life and the relationship of the couple in the context of sexuality in women with hysterectomy. Methods: Quantitative, cross-sectional and descriptive-correlational study. The sample is nonrandom, consisting of 129 women, mean age 55.82 years (± 3.97 years) undergoing hysterectomy, attending the gynecology consultation of a hospital in the central area of the country.). As a data collection instrument we used a questionnaire that allowed us to characterize sociodemographic, socio-professional, sexual and reproductive health, clinical and sexuality contexts. Also included was the WHOQOL-BREF Scale (WHOQOL Group, 1998, Barros, 2002) and the Sexual Satisfaction Inventory - female version (GRISS: Rust & Golombok, 1986), translated and adapted to the Portuguese population by Sandra Vilarinho and Pedro Nobre. (2006). Results: It was found that 50.4% of women did not change their sexuality experience after hysterectomy, contrary to 49.6% who reported as a decrease in sexual interest (37.2%), a decrease in self-esteem (9.3%) and the presence of pain (2.3%). Overall, women show sexual satisfaction (mean= 40.45±7.81). Regarding the perception of women (considering feeling more or less feminine) after hysterectomy, most women considered that they remained the same (56.6%). Regarding quality of life, the highest average value corresponds to the domain of social relations (average = 69.25±9.70), followed by the environment domain (average = 67.78±12.31). The reason for hysterectomy, hospital surgical complications, and postoperative hysterectomy consultation were variables with statistically significant relevance. Women who show more sexual satisfaction are the reason for the hysterectomy was benign gynecological pathology (mean=37.53; t=-5.664; p=0.000), with no surgical complications in the hospital (OM=59.95) (UMW=944.500; p=0.004), as well as those who reported having a surveillance appointment after hysterectomy (OM=60.09; UMW=652,000; p=0.001). Regarding the relationship between sexual satisfaction and perception as a woman (consider feeling more or less feminine) after hysterectomy, women who manifest more sexual satisfaction are those who consider that their perception as a woman after hysterectomy has improved (OM=48.67) and those who reported getting worse are less satisfied sexually (OM=82.76; (X2=11.703; p=0.003). Predictors of sexual satisfaction are age, overall quality of life and dimensions of quality of life. It was found that the physical, psychological and environmental domains of quality of life establish an inverse relationship and age, overall quality of life and the domain of social relations have a direct relationship with sexual satisfaction, suggesting that older women, A better perception of their overall quality of life, a better perception of their quality of life in the domain of social relationships reveal greater sexual satisfaction due to the lack of a problematic relationship. Conclusions: The results are important for future professional practice in Maternal, Obstetric and Gynecological Nursing, serving as a basis for intervention in women before and after hysterectomy, which require humanized and holistic care, without neglecting any of its dimensions, physical, psychological, sexual, social and family. Keywords: Hysterectomy, Sexuality, Couple Relationship

New insights into the origin of remote PPG signals in visible light and infrared

Remote photoplethysmography (PPG) is an optical measurement technique with established applications in vital signs monitoring. Recently, the consensual understanding of blood volume variations (BVVs) as the origin of PPG signals was challenged, raising validity concerns about the remote SpO2 methodology. Recognizing the imperative for new opto-physiological evidence, this investigation supports the volumetric hypothesis with living skin experiments and Monte Carlo simulations of remote PPG-amplitude in visible light (VIS) and infrared (IR). Multilayered models of the skin were developed to simulate the separate contributions from skin layers containing pulsatile arterioles to the PPG signal in the 450-1000 nm range. The simulated spectra were qualitatively compared with observations of the resting and compressed finger pad, and complemented with videocapillaroscopy. Our results indicate that remote PPG systems indeed probe arterial blood. Green wavelengths probe dermal arterioles while red-IR wavelengths also reach subcutaneous BVVs. Owing to stable penetration depths, the red-IR diagnostic window promotes the invariance of SpO2 measurements to skin non-homogeneities

Performance evaluation of virtual MIMO schemes for the UL OFDMA based systems

In this paper we propose and assess the performance of virtual MIMO or relay-assisted cooperative schemes designed for the UL OFDMA based systems. We consider the use of an antenna array at the base station and a single antenna at both the mobile terminal and relay. The proposed cooperative schemes emulate a MIMO channel with 2 transmit and M receive antennas. Two types of relays are considered: amplify-and-forward and selective decode-and-forward. We derive the instantaneous normalized capacities and both the outage capacities and bit error rate are compared against the noncooperative SISO and SIMO systems, considering different scenarios. The proposed relay-assisted schemes are suited for existing and for the future broadband wireless systems to increase the system capacity and coverage. © 2008 IEEE