Optimal Power Allocation for Multiuser Secure Communication in Cooperative Relaying Networks

We consider a cooperative relaying network in which a source communicates with a group of users in the presence of one eavesdropper. We assume that there are no source-user links and the group of users receive only retransmitted signal from the relay. Whereas, the eavesdropper receives both the original and retransmitted signals. Under these assumptions, we exploit the user selection technique to enhance the secure performance. We first find the optimal power allocation strategy when the source has the full channel state information (CSI) of all links. We then evaluate the security level through: i) ergodic secrecy rate and ii) secrecy outage probability when having only the statistical knowledge of CSIs.

Secure Wireless Key Establishment Using Retrodirective Array

In this paper a new method of establishing secret keys for wireless communications is proposed. A retrodirective array (RDA) that is configured to receive and re-transmit at different frequencies is utilized as a relay node. Specifically the analogue RDA is able to respond in ‘real-time’, reducing the required number of time slots for key establishment to two, compared with at least three in previous relay key generation schemes. More importantly, in the proposed architecture equivalent reciprocal wireless channels between legitimate keying nodes can be randomly updated within one channel coherence time period, leading to greatly increased key generation rates (KGRs) in slow fading environment. The secrecy performance of this RDA assisted key generation system is evaluated and it is shown that it outperforms previous relay key generation systems.

Physical Layer Security with Threshold-Based Multiuser Scheduling in Multi-antenna Wireless Networks

In this paper, we consider a multiuser downlink wiretap network consisting of one base station (BS) equipped with AA antennas, NB single-antenna legitimate users, and NE single-antenna eavesdroppers over Nakagami-m fading channels. In particular, we introduce a joint secure transmission scheme that adopts transmit antenna selection (TAS) at the BS and explores threshold-based selection diversity (tSD) scheduling over legitimate users to achieve a good secrecy performance while maintaining low implementation complexity. More specifically, in an effort to quantify the secrecy performance of the considered system, two practical scenarios are investigated, i.e., Scenario I: the eavesdropper’s channel state information (CSI) is unavailable at the BS, and Scenario II: the eavesdropper’s CSI is available at the BS. For Scenario I, novel exact closed-form expressions of the secrecy outage probability are derived, which are valid for general networks with an arbitrary number of legitimate users, antenna configurations, number of eavesdroppers, and the switched threshold. For Scenario II, we take into account the ergodic secrecy rate as the principle performance metric, and derive novel closed-form expressions of the exact ergodic secrecy rate. Additionally, we also provide simple and asymptotic expressions for secrecy outage probability and ergodic secrecy rate under two distinct cases, i.e., Case I: the legitimate user is located close to the BS, and Case II: both the legitimate user and eavesdropper are located close to the BS. Our important findings reveal that the secrecy diversity order is AAmA and the slope of secrecy rate is one under Case I, while the secrecy diversity order and the slope of secrecy rate collapse to zero under Case II, where the secrecy performance floor occurs. Finally, when the switched threshold is carefully selected, the considered scheduling scheme outperforms other well known existing schemes in terms of the secrecy performance and complexity tradeoff

Secure Multiple Amplify-and-Forward Relaying with Co-Channel Interference

We investigate the impact of co-channel interference on the security performance of multiple amplify-and-forward (AF) relaying networks, where N intermediate AF relays assist the data transmission from the source to the destination. The relays are corrupted by multiple co-channel interferers, and the information transmitted from the relays to destination can be overheard by the eavesdropper. In order to deal with the interference and wiretap, the best out of N relays is selected for security enhancement. To this end, we derive a novel lower bound on the secrecy outage probability (SOP), which is then utilized to present two best relay selection criteria, based on the instantaneous and statistical channel information of the interfering links. For these criteria and the conventional maxmin criterion, we quantify the impact of co-channel interference and relay selection by deriving the lower bound on the SOP. Furthermore, we derive the asymptotic SOP for each criterion, to explicitly reveal the impact of transmit power allocation among interferers on the secrecy performance, which offers valuable insights into practical design. We demonstrate that all selection criteria achieve full secrecy diversity order N, while the proposed in this paper two criteria outperform the conventional max-min scheme. 

Retrodirective Assisted Secure Wireless Key Establishment

In this paper a new type of architecture for secure wireless key establishment is proposed. A retrodirective array (RDA) that is configured to receive and re-transmit at different frequencies is utilized as a relay node. The RDA is able to respond in ‘real-time’, reducing the required number of time slots to two. More importantly, in this architecture equivalent reciprocal wireless channels between legitimate keying nodes can be randomly updated within one channel coherence time period, leading to greatly increased key generation rates (KGRs) in slow fading environment. The secrecy performance of this RDA assisted key generation system is evaluated under several eavesdropping strategies and it is shown that it outperforms previous relay key generation systems.

Spectral Signature Secured Retrodirective Array

A novel retrodirective array (RDA) architecture is proposed which utilises a special case spectral signature embedded within the data payload as pilot signals. With the help of a pair of phase-locked-loop (PLL) based phase conjugators (PCs) the RDA’s response to other unwanted and/or unfriendly interrogating signals can be disabled, leading to enhanced secrecy performance directly in the wireless physical layer. The effectiveness of the proposed RDA system is experimentally demonstrated.

Aspectos da qualidade de vida de pacientes com coinfecção HIV/tuberculose

Investigar a qualidade de vida de pacientes com coinfecção HIV/ tuberculose e apreender as mudanças impostas para viver simultaneamente com estas doenças transmissíveis. Métodos: Pesquisa com abordagem qualiquantitativa, realizada em ambulatório especializado em Fortaleza, Brasil, entre 2009 e 2010, com 34 coinfectados. Para coleta de dados foi utilizada uma escala de qualidade de vida, denominada HAT-QoL que possui 42 itens e questões abertas para possibilitar perceber as mudanças em face das doenças. Resultados: A maioria dos participantes tinha tuberculose na forma pulmonar, eram homens, com pouca escolaridade. A qualidade de vida mostrou-se prejudicada nos domínios relacionados às questões econômicas, sexuais e de sigilo. Ainda, foi evidenciado, que a coinfecção impõe mudanças no cotidiano que corroboram e ampliam o comprometimento da qualidade de vida. Conclusão: Vivenciar a coinfecção, mesmo com terapêutica adequada, produz alterações na vida dos infectados, cujas repercussões podem ser amenizadas com intervenções que promovam a saúde

Desenvolvimento e Estudo da Validade Facial do Questionário de Motivações para Revelar/Não Revelar a Parentalidade Não-Genética por Doação de Gâmetas

Introdução: A parentalidade é um papel muito valorizado socialmente. No entanto, para casais com infertilidade o desempenho deste papel pode implicar tratamentos de fertilidade, alguns deles com recurso a gâmetas de dador. Para os casais que recorrem a gâmetas de dador, surge uma outra preocupação: contar à criança a origem da sua conceção ou manter segredo. Ainda que as motivações que influenciam este processo de decisão tenham sido alvo de estudo, em Portugal a investigação relativa a este tema é escassa. Objetivos: A presente investigação pretendeu desenvolver e estudar a validade facial do Questionário de Motivações para Revelar/Não Revelar a Parentalidade não Genética por Doação de Gâmetas (QMRDG), o qual se destina a avaliar as principais motivações que influenciam o processo de tomada de decisão dos pais que recorrem a gâmetas de dador relativamente a contar ou não contar ao/à seu/sua filho/a a origem da sua conceção. Pretendeu-se ainda explorar a relação entre os sintomas emocionais negativos e o sentido de competência parental nos diferentes grupos em estudo (pais que já contaram à criança, pais que decidiram não contar e pais que ainda não contaram). Metodologia: Estudo exploratório conduzido numa amostra de 21 participantes que recorrem a tratamento de fertilidade com recurso a gâmetas de dador, tendo tido filhos resultantes desse mesmo tratamento, com idades compreendidas entre os 30 e 49 anos. Os participantes preencheram um conjunto de questionários numa plataforma online, tendo o estudo sido divulgado pela Associação Portuguesa de Fertilidade. Resultados: Os dados obtidos indicam que a maioria dos pais ainda não contou ao/à seu/sua filho/a sua origem genética devido ao facto de a criança ser ainda muito pequena, encontrando-se estes com intenção de revelar à criança. Dos pais que já contaram, as motivações que mais influenciaram a decisão basearam-se na falta de motivos para omitir, na importância dada à honestidade, no direito do conhecimento das origens genéticas e na transparência no seio familiar. Face às motivações para não contar, das que mais influenciaram os pais salienta-se a pouca importância dada à genética. O QMRDG revelou possuir validade facial não tendo sido reportada a existência de itens ambíguos ou de difícil compreensão. Discussão: A tendência dos pais no presente estudo foi de contar ao/à seu/sua filho/a a origem da sua conceção, sendo também esta a tendência reportada em estudos mais recentes. Verificou-se a existência de algumas limitações no estudo, nomeadamente o tamanho da amostra. No entanto, o QMRDG mostrou possuir validade facial, podendo constituir-se como um instrumento útil na prática clínica e na investigação com pessoas que estejam a realizar tratamento de fertilidade com recurso a gâmetas de dador. / Introduction: Parenting is a highly valued social role. However, for couples dealing with infertility this role can involve fertility treatments, and for some of them donorassisted reproduction. For couples who use third party reproduction, another concern can emerge: tell the child about the donor conception, or preserve secrecy. Although arguments for decision making have been studied, in Portugal research on this topic is scanty. Objectives: The current study sought out to develop and study the facial validity of Motivations for Disclosing/Not Disclosing Non-genetic Parenthood through Gamete Donation (QMRDG), which is designed to assess motivations that influence the decision-making process of parents who use gamete donation regarding tell or not to tell to his/her son/daughter his/her conception. The existence of differences concerning emotional negative symptoms and parenting sense of competence in three groups (parents that already disclosed, parents that decided not to disclose and parents that did not decide what to do) was also explored. Methods: This exploratory study was conducted in sample of 21 participants who undergone third-party reproduction treatment and became parents. Participants´ age ranged from 30 to 49 years. Participants completed a set of questionnaires through an online platform. The study was advertised by Associação Portuguesa de Fertilidade. Results: Data showed that most parents did not disclose to their child their donor conception due to the fact that the child is still very young, but their intention seems to be to disclose in the future. For parents who have disclosed, core motivations for that decision are based on the lack of reasons for omitting, on the importance of honesty, on the right to know genetic origins and on transparency in the family. Concerning motivations for not disclosing the little importance given to genetics emerges as one of the most important ones. QMRDG revealed good facial validity. The existence of ambiguous or difficult to understand items has not been reported. Discussion: In our study parent’s tendency was to disclose to his/her son/daughter his/her donor conception and this is also the trend reported in recent studies. There are some methodological limitations that should be considered mainly due to the sample size. However, the QMRDG proved to be an instrument showing facial validity, and it can be a useful tool in clinical practice and research with people who are pursuing fertility treatment with gamete donation.

Non-Symbolic Fragmentation

This paper reports on the use of non-symbolic fragmentation of data for securing communications. Non-symbolic fragmentation, or NSF, relies on breaking up data into non-symbolic fragments, which are (usually irregularly-sized) chunks whose boundaries do not necessarily coincide with the boundaries of the symbols making up the data. For example, ASCII data is broken up into fragments which may include 8-bit fragments but also include many other sized fragments. Fragments are then separated with a form of path diversity. The secrecy of the transmission relies on the secrecy of one or more of a number of things: the ordering of the fragments, the sizes of the fragments, and the use of path diversity. Once NSF is in place, it can help secure many forms of communication, and is useful for exchanging sensitive information, and for commercial transactions. A sample implementation is described with an evaluation of the technology.

A cultura e as características qualitativas da informação financeira: evidência empírica a partir do relato de entidades cotadas na União Europeia

Mestrado em Contabilidade

Aspectos da qualidade de vida de pacientes com coinfecção HIV/tuberculose

Investigar a qualidade de vida de pacientes com coinfecção HIV/ tuberculose e apreender as mudanças impostas para viver simultaneamente com estas doenças transmissíveis. Métodos: Pesquisa com abordagem qualiquantitativa, realizada em ambulatório especializado em Fortaleza, Brasil, entre 2009 e 2010, com 34 coinfectados. Para coleta de dados foi utilizada uma escala de qualidade de vida, denominada HAT-QoL que possui 42 itens e questões abertas para possibilitar perceber as mudanças em face das doenças. Resultados: A maioria dos participantes tinha tuberculose na forma pulmonar, eram homens, com pouca escolaridade. A qualidade de vida mostrou-se prejudicada nos domínios relacionados às questões econômicas, sexuais e de sigilo. Ainda, foi evidenciado, que a coinfecção impõe mudanças no cotidiano que corroboram e ampliam o comprometimento da qualidade de vida. Conclusão: Vivenciar a coinfecção, mesmo com terapêutica adequada, produz alterações na vida dos infectados, cujas repercussões podem ser amenizadas com intervenções que promovam a saúde

Should female health providers be involved in medical male circumcision? Narratives of newly circumcised men in Malawi

Background The Malawi government has endorsed voluntary medical male circumcision (VMMC) as a biomedical strategy for HIV prevention after a decade of debating its effectiveness in the local setting. The “policy” recommends that male circumcision (MC) should be clinically based, as opposed to the alternative of traditional male circumcision (TMC). Limited finances, acceptability concerns, and the health system’s limited capacity to meet demand are among the challenges threatening the mass rollout of VMMC. In terms of acceptability, the gender of clinicians conducting the operations may particularly influence health facility-based circumcision. This study explored the acceptability, by male clients, of female clinicians taking part in the circumcision procedure. Methods Six focus group discussions (FGDs) were conducted, with a total of 47 newly circumcised men from non-circumcising ethnic groups in Malawi participating in this study. The men had been circumcised at three health facilities in Lilongwe District in 2010. Data were audio recorded and transcribed verbatim. Data were analysed using narrative analysis. Results Participants in the FGDs indicated that they were not comfortable with women clinicians being part of the circumcising team. While few mentioned that they were not entirely opposed to female health providers’ participation, arguing that their involvement was similar to male clinicians’ involvement in child delivery, most of them opposed to female involvement, arguing that MC was not an illness that necessitates the involvement of clinicians regardless of their gender. Most of the participants said that it was not negotiable for females to be involved, as they could wait until an all-male clinician team could be available. Thematically, the arguments against female clinicians’ involvement include sexual undertones and the influences of traditional male circumcision practices, among others. Conclusion Men preferred that VMMC should be conducted by male health providers only. Traditionally, male circumcision has been a male-only affair shrouded in secrecy and rituals. Although being medical, this study strongly suggested that it may be difficult for VMMC to immediately move to a public space where female health providers can participate, even for men coming from traditionally non-circumcising backgrounds.

Análise bioética da utilização de imagens de pacientes em mídias sociais eletrônicas

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Ciências da Saúde, Programa de Pós-Graduação em Bioética, 2016.

Indicadores do perfil profissional do psicólogo escolar das equipes especializadas de apoio à aprendizagem da Secretaria de Educação do DF

Dissertação (mestrado)—Universidade de Brasília, Instituto de Psicologia, Programa de Pós-graduação em Processos de Desenvolvimento Humano e Saúde, 2016.

Acesso à informação e intimidade : um dilema do Estado Democrático de Direito

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Direito, Programa de Pós-Graduação em Direito, 2016.