Infection control strategies for preventing the transmission of meticillin-resistant Staphylococcus aureus (MRSA) in nursing homes for older people (Review)

Background: Nursing homes for older people provide an environment likely to promote the acquisition and spread of meticillin-resistant Staphylococcus aureus (MRSA), putting residents at increased risk of colonisation and infection. It is recognised that infection prevention and control strategies are important in preventing and controlling MRSA transmission.

Objectives: To determine the effects of infection prevention and control strategies for preventing the transmission of MRSA in nursing homes for older people.

Search methods: In August 2013, for this third update, we searched the Cochrane Wounds Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), Database of Abstracts of Reviews of Effects (DARE, The Cochrane Library), Ovid MEDLINE, OVID MEDLINE (In-process and Other Non-Indexed Citations), Ovid EMBASE, EBSCO CINAHL, Web of Science and the Health Technology Assessment (HTA) website. Research in progress was sought through Current Clinical Trials, Gateway to Reseach, and HSRProj (Health Services Research Projects in Progress).

Selection criteria: All randomised and controlled clinical trials, controlled before and after studies and interrupted time series studies of infection prevention and control interventions in nursing homes for older people were eligible for inclusion.

Data collection and analysis: Two review authors independently reviewed the results of the searches. Another review author appraised identified papers and undertook data extraction which was checked by a second review author.

Main results: For this third update only one study was identified, therefore it was not possible to undertake a meta-analysis. A cluster randomised controlled trial in 32 nursing homes evaluated the effect of an infection control education and training programme on MRSA prevalence. The primary outcome was MRSA prevalence in residents and staff, and a change in infection control audit scores which measured adherence to infection control standards. At the end of the 12 month study, there was no change in MRSA prevalence between intervention and control sites, while mean infection control audit scores were significantly higher in the intervention homes compared with control homes.

Authors' conclusions: There is a lack of research evaluating the effects on MRSA transmission of infection prevention and control strategies in nursing homes. Rigorous studies should be conducted in nursing homes, involving residents and staff to test interventions that have been specifically designed for this unique environment.

Tooth replacement for partially dentate elders: a willingness-to-pay analysis

Objectives: The primary aim of this study was to investigate partially dentate elders’ willingness-to-pay (WTP) for two different tooth replacement strategies: using Removable Partial Dentures (RPDs) and, functionally orientated treatment (SDA). The secondary aim was to measure the same patient group’s WTP for dental implants. Methods: Patients who had completed a previous RCT comparing two tooth replacement strategies (RPDs and SDA) were recruited. 59 patients were asked to indicate their WTP for treatment to replace missing teeth in a number of hypothetical scenarios using the payment card method of contingency evaluation coupled to different costs. Data were collected on patients’ social class, longest held occupation, income levels and social circumstances. Results: The median age for the patient sample was 72.0 years (IQR: 71-75 years). Patients who had previously been provided with RPDs indicated that their WTP for this treatment strategy was significantly higher than those patients who had received SDA treatment (Mann-Whitney U Test: p<0.001). This group were also WTP a higher price for SDA treatment than those patients who had previously been treated according to this modality (Mann-Whitney U Test: p=0.005). The results indicated that patients’ age was not correlated with WTP but both social class and current income levels were significantly correlated (Spearman’s rank correlation: p<0.05). Patients in both treatment groups exhibited llittle WTP for dental implant treatment with a median price recorded which was lower than either RPD or SDA treatment. Conclusions: Amongst this patient cohort previous treatment experience had a strong influence on WTP as did social class and current income levels. The patients’ WTP indicated that they did not value dental implants over simpler forms of tooth replacement such as RPDs or a SDA approach.

Justifying accounting change through global discourses and legitimation strategies. The case of the UK central government.

Accounting has been viewed, especially through the lens of the recent managerial reforms, as a neutral technology that, in the hands of rational managers, can support effective and efficient decision making. However, the introduction of new accounting practices can be framed in a variety of ways, from value-neutral procedures to ideologically-charged instruments. Focusing on financial accounting, budgeting and performance management changes in the UK central government, and through extensive textual analysis and interviews in three government departments, this paper investigates: how accounting changes are discussed and introduced at the political level through the use of global discourses; and what strategies organisational actors subsequently use to talk about and legitimate such discourses at different organisational levels. The results shows that in political discussions there is a consistency between the discourses (largely NPM) and the accounting-related changes that took place. The research suggests that a cocktail of legitimation strategies was used by organisational actors to construct a sense of the changes, with authorisation, often in combination with, at the very least, rationalisation strategies most widely utilised. While previous literature posits that different actors tend to use the same rhetorical sequences during periods of change, this study highlights differences at different organisational levels.

Comparison of granulometric methods and sampling strategies used in marine habitat classification and Ecological Status assessment

Sediment particle size analysis (PSA) is routinely used to support benthic macrofaunal community distribution data in habitat mapping and Ecological Status (ES) assessment. No optimal PSA Method to explain variability in multivariate macrofaunal distribution has been identified nor have the effects of changing sampling strategy been examined. Here, we use benthic macrofaunal and PSA grabs from two embayments in the south of Ireland. Four frequently used PSA Methods and two common sampling strategies are applied. A combination of laser particle sizing and wet/dry sieving without peroxide pre-treatment to remove organics was identified as the optimal Method for explaining macrofaunal distributions. ES classifications and EUNIS sediment classification were robust to changes in PSA Method. Fauna and PSA samples returned from the same grab sample significantly decreased macrofaunal variance explained by PSA and caused ES to be classified as lower. Employing the optimal PSA Method and sampling strategy will improve benthic monitoring. © 2012 Elsevier Ltd.

Surgical strategies for coexisting glaucoma and cataract: an evidence-based update.

OBJECTIVE:

To assess short- and long-term control of intraocular pressure (IOP) with different surgical treatment strategies for coexisting cataract and glaucoma.

DESIGN:

Systematic literature review and analysis.

METHOD:

We performed a search of the published literature to identify all eligible articles pertaining to the surgical management of coexisting cataract and glaucoma in adults. One investigator abstracted the content of each article onto a custom-designed form. A second investigator corroborated the findings. The evidence supporting different approaches was graded by consensus as good, fair, weak, or insufficient.

MAIN OUTCOME MEASURES:

Short-term (24 hours or fewer) and long-term (more than 24 hours) IOP control.

RESULTS:

The evidence was good that long-term IOP is lowered more by combined glaucoma and cataract operations than by cataract operations alone. On average, the IOP was 3 to 4 mmHg lower in the combined groups with fewer medications required. The evidence was weak that extracapsular cataract extraction (ECCE) alone results in short-term increase in IOP and was insufficient to determine the short-term impact of phacoemulsification cataract extraction (PECE) on IOP in glaucoma patients. The evidence was weak that short-term IOP control was better with ECCE or PECE combined with an incisional glaucoma procedure compared with ECCE or PECE alone. The evidence was also weak (but consistent) that long-term IOP is lowered by 2 to 4 mmHg after ECCE or PECE. Finally, there was weak evidence that combined PECE and trabeculectomy produces slightly worse long-term IOP control than trabeculectomy alone, and there was fair evidence that the same is true for ECCE combined with trabeculectomy.

CONCLUSIONS:

There is strong evidence for better long-term control of IOP with combined glaucoma and cataract operations compared with cataract surgery alone. For other issues regarding surgical treatment strategies for cataract and glaucoma, the available evidence is limited or conflicting.

Illness perceptions and coping in physical health conditions: A meta-analysis

Objective: There is a considerable body of research linking elements of Leventhal’s Common Sense Model (CSM) to emotional well-being/distress outcomes among people with physical illness. The present study aims to consolidate this literature and examine the evidence for the role of coping strategies within this literature.
Methods: A systematic review was conducted where the outcomes of interest were: depression, anxiety and quality of life. A total of 1050 articles were identified and 31 articles were considered eligible to be included in the review.
Results: Across a range of illnesses, perceptions of consequences of the illness and emotional representations were consistently the illness perceptions with the strongest relationship with the outcomes. Coping variables tend to be stronger predictors of outcomes than the illness perception variables. The evidence for the mediating effect of coping was inconsistent.
Conclusions: Illness perceptions and coping have an important role to play in the explanation of distress outcomes across a range of physical health conditions. However, some clarity about the theoretical position of coping in relation to illness perceptions, and further longitudinal work is needed if we are to apply this information to the design of interventions for the improvement of psychological health among people with physical health conditions.

Tooth replacement for partially dentate elders: a willingness-to-pay analysis

Objectives: The primary aim of this study was to investigate partially dentate elders’ willingness-to-pay (WTP) for two different tooth replacement strategies: using Removable Partial Dentures (RPDs) and, functionally orientated treatment (SDA). The secondary aim was to measure the same patient group’s WTP for dental implants.Methods: Patients who had completed a previous RCT comparing two tooth replacement strategies (RPDs and SDA) were recruited. 59 patients were asked to indicate their WTP for treatment to replace missing teeth in a number of hypothetical scenarios using the payment card method of contingency evaluation coupled to different costs. Data were collected on patients’ social class, longest held occupation, income levels and social circumstances.Results: The median age for the patient sample was 72.0 years (IQR: 71-75 years). Patients who had previously been provided with RPDs indicated that their WTP for this treatment strategy was significantly higher than those patients who had received SDA treatment (Mann-Whitney U Test: p<0.001). This group were also WTP a higher price for SDA treatment than those patients who had previously been treated according to this modality (Mann-Whitney U Test: p=0.005). The results indicated that patients’ age was not correlated with WTP but both social class and current income levels were significantly correlated (Spearman’s rank correlation: p<0.05).Patients in both treatment groups exhibited llittle WTP for dental implant treatment with a median price recorded which was lower than either RPD or SDA treatment.Conclusions: Amongst this patient cohort previous treatment experience had a strong influence on WTP as did social class and current income levels. The patients’ WTP indicated that they did not value dental implants over simpler forms of tooth replacement such as RPDs or a SDA approach.

Progressing from internal to supply chain level environmental strategies: The influence of internal support processes

The need for companies to consider the environmental impact of their operations and supply chains has been highlighted in the literature. However, few studies appear to consider how companies’ progress from proactive environmental strategies implemented at the internal, operations level to proactive environmental strategies implemented at the supply chain level. This study assesses the implementation process through the lens of the natural resource-based view and dynamic capabilities perspective. First, the link between the internal strategy ‘pollution prevention’ and the supply chain strategy ‘process stewardship’ is assessed. Second, the mediating influence of the internal support processes ‘integration’ and ‘learning’ on the implementation process is considered. Data collected from a sample of 1200 UK-based food manufacturing companies is analysed using multiple regression analysis. The findings suggest that the progression to environmental efforts at the supply chain level begins with internally-based environmental efforts and that the integration of these efforts and experience gained from them are important supporting factors in this progression.

Analysis of multirate behavior in electronic systems

Esta tese insere-se na área da simulação de circuitos de RF e microondas, e visa o estudo de ferramentas computacionais inovadoras que consigam simular, de forma eficiente, circuitos não lineares e muito heterogéneos, contendo uma estrutura combinada de blocos analógicos de RF e de banda base e blocos digitais, a operar em múltiplas escalas de tempo. Os métodos numéricos propostos nesta tese baseiam-se em estratégias multi-dimensionais, as quais usam múltiplas variáveis temporais definidas em domínios de tempo deformados e não deformados, para lidar, de forma eficaz, com as disparidades existentes entre as diversas escalas de tempo. De modo a poder tirar proveito dos diferentes ritmos de evolução temporal existentes entre correntes e tensões com variação muito rápida (variáveis de estado activas) e correntes e tensões com variação lenta (variáveis de estado latentes), são utilizadas algumas técnicas numéricas avançadas para operar dentro dos espaços multi-dimensionais, como, por exemplo, os algoritmos multi-ritmo de Runge-Kutta, ou o método das linhas. São também apresentadas algumas estratégias de partição dos circuitos, as quais permitem dividir um circuito em sub-circuitos de uma forma completamente automática, em função dos ritmos de evolução das suas variáveis de estado. Para problemas acentuadamente não lineares, são propostos vários métodos inovadores de simulação a operar estritamente no domínio do tempo. Para problemas com não linearidades moderadas é proposto um novo método híbrido frequência-tempo, baseado numa combinação entre a integração passo a passo unidimensional e o método seguidor de envolvente com balanço harmónico. O desempenho dos métodos é testado na simulação de alguns exemplos ilustrativos, com resultados bastante promissores. Uma análise comparativa entre os métodos agora propostos e os métodos actualmente existentes para simulação RF, revela ganhos consideráveis em termos de rapidez de computação.

Geochemical analysis of sediments from a polluted waterway in the vicinity of a metallurgical plant, Minas Gerais, Brazil

Mining and metallurgical industries are the most responsible for heavy metal contamination. These contaminants are often associated to poor management strategies and the lack of suitable containment areas. This is the case of one of the largest metal alloy producers in the São Francisco river basin, in Minas Gerais state, Brazil. During operation, the tailings of this activity have been accumulated in the surrounding area, leading to heavy metal contamination (Mn, Cu, Zn, Ni, Pb, Cd, Cr and As), much above the critical levels, which accumulate in the sediments of the nearby waterways, in the soils of the drainage area, and in the water column. In this work we are going to discuss both the contamination level and its extent in the Consciência river, a small tributary of the São Francisco river, the longest river entirely Brazilian, by analyzing the geochemistry and mineralogy of the accumulated sediments. It will be also discuss the reclamation strategies of this site and the impact on the environment.

The analysis of political will and its role in leadership: a study of portuguese mayors

This thesis analyses the concept of Political Will, suggests its operationalization and establishes a typological theory that provides the necessary support for the diverse strategies of action of a leader. It claims that political leadership styles articulate a choice of action that results from the Political Will of a leader, which is determined by his intention and his discerned possibilities to act. One main research question guided our research: How does a political leader select and change his leadership style? The most illustrative literature on political leadership is reviewed and the characteristics of democratic governance are analyzed. This is followed by an overview of the most noteworthy theories on the theme and a claim for the need of concept coherence, given the multiplicity of the existent standpoints. After that, we concentrate on leadership styles, with a focus on the local governance context. Human action and intentionality are addressed with particular attention, as well as the motivational drivers for action, in order to advance a conceptualization of Political Will through two dimensions: intention and possibility. This analysis led to a number of relevant propositions: (1) Political Will ‘exists’ when the agent has the intent and the possibility to act; (2) these two dimensions ‘translate’ simultaneously what the agent believes he must do and can do; (3) Intention and possibility reflect diverse but limited worldviews; (4) political leadership styles result from the agent’s Political Will; (5) different combinations of the expected and actual worldviews result in different leadership styles; and (6) political leadership styles can change accordingly to several strategies which allow conformity or reflect reaction to worldviews. We suggested the operationalization of the two dimensions of Political Will through the analytical tool of Grid-group Theory, which provided the identification of the heuristic devices that allowed further comprehension on the subjectivity of the agent’s choice. Four standard property spaces – representing four types of leadership styles – result from a preliminary approach to this process. Afterwards, and because these dimensions operate simultaneously, we advance on the analysis and suggest some plausible heuristical conflicts to happen and describe which consequences, strategies and type migrations are conceivable. An inclusive and more complete set of resulting property spaces renders fourteen different types of leadership styles and sixty different predictable causal paths that result from the expected migration strategies. Case-studies were conducted as plausibility probes designed to provide improvements to our theoretical claims and addressed the cases we selected for research purposes: Portuguese Mayors. The findings from five case studies are discussed and the probable impact and congruence of each with the theoretical claims are assessed. The communalities of the causal mechanisms related to the function of intention and possibility as the dimensions of Political Will and their role in explaining different leadership styles are, finally, addressed. To conclude, we advance some repercussions, mainly in the public policies field of research, and suggest a number of different and necessary paths for further work.

Bottom up strategies for the morphology control of BaTiO3 particulates

As propriedades funcionais dos materiais ferroeléctricos tais como a polarização reversível, piroelectricidade, piezoelectricidade, elevada actividade óptica não linear e comportamento dieléctrico não linear são fundamentais para a sua aplicação em sensores, microactuadores, detectores de infravermelhos, filtros de fase de microondas e memórias não-voláteis. Nos últimos anos, motivado pelas necessidades industriais de redução do tamanho dos dispositivos microelectrónicos, aumentando a eficiência volumétrica, tem sido feito um grande esforço ao nível da investigação para desenvolver estruturas ferroeléctricas à escala micro- e nano- métrica. É sabido que a redução de tamanho em materiais ferroeléctricos afecta significamente as suas propriedades. Neste sentido e considerando que foi previsto teoreticamente por cálculos ab initio que estruturas do tipo nanocilindros e nanodiscos apresentariam um novo tipo de ordem ferroeléctrica e, na expectativa de alcançar conhecimento para o desenvolvimento de uma nova geração de dispositivos microelectróncos, existe um grande interesse em desenvolver métodos de fabrico de nanoestruturas ferroeléctricas unidimensionais (1D) tais como nanocilindros e nanotubos. As estratégias de fabrico de nanoestruturas 1D até agora descritas na literatura indicam claramente as dificuldades inerentes à sua preparação. Existem duas grandes vias de síntese destas nanoestruturas: i) o método “topdown” que consiste na redução de tamanho de um dado material até à obtenção duma estrutura 1D; e ii) o método “bottom-up” em que átomos, iões e moléculas são agrupados para formar um material 1D. O método “top down” envolve em geral técnicas de desgaste, como o uso do feixe de electrões, que apesar de permitirem elevada precisão no posicionamento e no controlo do tamanho, falham em termos de resolução, exigem muito tempo e causam facilmente defeitos que deterioram as propriedades físicas destes materiais. Na metodologia “bottom up” a utilização de moléculas ou estruturas “molde” tem sido a mais explorada. As estructuras 1D podem também ser preparadas sem recorrer a “moldes”. Neste caso a agregação orientada é promovida pelo recurso a aditivos que controlam o crescimento dos cristais em direcções preferenciais. Neste contexto, neste trabalho utilizaram-se duas estratégias “bottom up” de baixo custo para a preparação de nanopartículas de titanato de bário (BaTiO3) com morfologia controlada: 1) síntese química (em solução e em fase vapor) com utilização de nanotubos de titanato TiNTs) como “moldes” e precursores de titânio 2) síntese química em solução com presença de aditivos. Os nanotubos de titanato de sódio foram preparados por síntese hidrotermal. Como existiam muitas dúvidas acerca da natureza estrutural e do mecanismo de formação dos NTs, a parte inicial do trabalho foi dedicada à realização de um estudo sistemático dos parâmetros intervenientes na síntese e à caracterização da sua estrutura e microestrutura. Foi demonstrado que os NTs têm a fórmula geral A2Ti2O5 (A = H+ or Na+), e não TiO2 (anátase) com defendido por vários autores na literatura, e podem ser preparados por método hidrotermal em meio fortemente alcalino usando como fonte de titânio TiO2 comercial na forma de anátase ou rútilo. A menor reactividade do rútilo exige temperaturas de síntese superiores ou tempos de reacção mais longos. A forma tubular resulta do tratamento hidrotermal e não de processos de lavagem e neutralização subsequentes. Se os NTs forem tratados após a síntese hidrotérmica em água a 200 ºC, transformam-se em nanocilindros. Uma das partes principais desta tese consistiu na investigação do papel dos NTs de titanato no crescimento anisotrópico de BaTiO3. O potencial funcionamento dos NTs como “moldes” para além de precursores foi testado em reacção com hidróxido de bário em síntese em solução e por reacção com um precursor orgânico de bário em fase vapor. Tendo por base os estudos cinéticos realizados, bem como as alterações estruturais e morfológicas das amostras, é possível concluir que a formação do BaTiO3 a partir de NTs de titanato de sódio, ocorre por dois mecanismos dependendo da temperatura e tempo de reacção. Assim, a baixa temperatura e curto tempo de reacção verifica-se que se formam partículas dendríticas de BaTiO3 cuja superfície é bastante irregular (“wild”) e que apresentam estrutura pseudo-cúbica. Estas partículas formam-se por reacção topotáctica na fronteira dos nanotubos de titanato de sódio. A temperaturas mais altas e/ou reacções mais longas, a reacção é controlada por um mecanismo de dissolução e precipitação com formação de dendrites de BaTiO3 tetragonais com superfície mais regular (“seaweed”). A microscopia de força piezoeléctrica mostrou que as dendrites “seaweeds“ possuem actividade piezoeléctrica superior à das dendrites “wild”, o que confirma o papel desempenhado pela estrutura e pela concentração de defeitos na rede na coerência e ordem ferroeléctrica de nanoestruturas. Os nossos resultados confirmam que os NTs de titanato não actuam facilmente como “moldes” na síntese em solução de BaTiO3 já que a velocidade de dissolução dos NTs em condições alcalinas é superior à velocidade de formação do BaTiO3. Assumindo que a velocidade de reacção dos NTs com o precursor de bário é superior em fase vapor, efectuou-se a deposição de um precursor orgânico de bário por deposição química de vapor sobre um filme de NTs de titnato de sódio depositados por deposição electroforética. Estudou-se a estabilidade dos NTs nas diferentes condições do reactor. Quando os NTs são tratados a temperaturas superiores a 700 ºC, ocorre a transformação dos NTs em nanocilindros de anatase por um mecanismo de agregação orientada. Quando se faz a deposição do precursor de bário, seguida de calcinação a 700 ºC em atmosfera oxidante de O2, verifica-se que a superficie dos NTs fica coberta com nanocristais de BaTiO3 independentemente da concentração de bário. O papel dos NTs de titanato no crescimento anisotrópico de BaTiO3 em fase vapor é assim descrito pela primeira vez. Em relação à metodologias de crescimento de partículas na ausência de “moldes” mas com aditivos fez-se um estudo sistemático utilizando 5 aditivos de natureza differente. As diferenças entre aditivos foram sistematizadas tendo em conta as diferenças estruturais e morfológicas verificadas. Está provado que os aditivos podem funcionar como modificadores de crescimento cristalino por alteração do seu padrão de crescimento ou por alteração da cinética de crescimento das faces cristalográficas do cristal. Entre os aditivos testados verificou-se que o ácido poliacrilíco adsorve em faces específicas do BaTiO3 alterando a cinética de crescimento e induzindo a agregação orientada das partículas. O polivinilpirrolidona, o docecilsulfato de sódio e hidroxipropilmetilcelulose actuam mais como inibidores de crescimento do que como modificadores do tipo de crescimento. A D-frutose aumenta a energia de activação da etapa de nucleação não ocorrendo formação de BaTiO3 para as mesmas condições dos outros aditivos. Esta tese clarifica o papel dos NTs de titanato de sódio enquanto precursores e “moldes” no crescimento anisotrópico de BaTiO3 em solução e em fase vapor. É feita também a abordagem do controlo morfológico do BaTiO3 através do uso de aditivos. As estratégias de preparação de BaTiO3 propostas são de baixo custo, reprodutíveis e fáceis de efectuar. Os resultados contribuem para uma melhor compreensão da relação tamanho – morfologia – propriedade em materiais ferroeléctricos nanométricos com vista à sua potencial aplicação.

Analysis, modeling, design and optimization of future communications systems: from theory to practice

Esta tese descreve uma framework de trabalho assente no paradigma multi-camada para analisar, modelar, projectar e optimizar sistemas de comunicação. Nela se explora uma nova perspectiva acerca da camada física que nasce das relações entre a teoria de informação, estimação, métodos probabilísticos, teoria da comunicação e codificação. Esta framework conduz a métodos de projecto para a próxima geração de sistemas de comunicação de alto débito. Além disso, a tese explora várias técnicas de camada de acesso com base na relação entre atraso e débito para o projeto de redes sem fio tolerantes a atrasos. Alguns resultados fundamentais sobre a interação entre a teoria da informação e teoria da estimação conduzem a propostas de um paradigma alternativo para a análise, projecto e optimização de sistemas de comunicação. Com base em estudos sobre a relação entre a informação recíproca e MMSE, a abordagem descrita na tese permite ultrapassar, de forma inovadora, as dificuldades inerentes à optimização das taxas de transmissão de informação confiáveis em sistemas de comunicação, e permite a exploração da atribuição óptima de potência e estruturas óptimas de pre-codificação para diferentes modelos de canal: com fios, sem fios e ópticos. A tese aborda também o problema do atraso, numa tentativa de responder a questões levantadas pela enorme procura de débitos elevados em sistemas de comunicação. Isso é feito através da proposta de novos modelos para sistemas com codificação de rede (network coding) em camadas acima da sua camada física. Em particular, aborda-se a utilização de sistemas de codificação em rede para canais que variam no tempo e são sensíveis a atrasos. Isso foi demonstrado através da proposta de um novo modelo e esquema adaptativo, cujos algoritmos foram aplicados a sistemas sem fios com desvanecimento (fading) complexo, de que são exemplos os sistemas de comunicação via satélite. A tese aborda ainda o uso de sistemas de codificação de rede em cenários de transferência (handover) exigentes. Isso é feito através da proposta de novos modelos de transmissão WiFi IEEE 801.11 MAC, que são comparados com codificação de rede, e que se demonstram possibilitar transferência sem descontinuidades. Pode assim dizer-se que esta tese, através de trabalho de análise e de propostas suportadas por simulações, defende que na concepção de sistemas de comunicação se devem considerar estratégias de transmissão e codificação que sejam não só próximas da capacidade dos canais, mas também tolerantes a atrasos, e que tais estratégias têm de ser concebidas tendo em vista características do canal e a camada física.

Technology-related strategies in labour-intensive industries from Southern European Regions: consequences for local employment

Tese dout., Economia, Universidade do Algarve, 2010

Androgens and Mating Systems in Fish: Intra- and Inter-specific Analysis

One of the predictions of the ‘challenge hypothesis’ (Wingfield et al., 1990) is that androgen patterns during the breeding season should vary among species according to the parenting and mating system. Here we assess this prediction of the challenge hypothesis both at the intra- and at the inter-specific level. To test the hypothesis at the inter-specific level, a literature survey on published androgen pat- terns from teleost fish with different mating systems was carried out. The results confirm the predicted effect of mating system on andro- gen levels. To test the hypothesis at an intra-specific level, a species with flexible reproductive strategies (i.e. monogamy vs. polygyny), the Saint Peter’s fish was studied. Polygynous males had higher 11- ketotestosterone levels. However, males implanted with methyl-tes- tosterone did not became polygynous and the variation of the ten- dency to desert their pair mates was better explained by the repro- ductive state of the female partner. This result stresses the point that the effects of behaviour on hormones cannot be considered without respect to the social context.