Linear transmitter design for MSAT terminals

One of the factors that will undoubtedly influence the choice of modulation format for mobile satellites, is the availability of cheap, power-efficient, linear amplifiers for mobile terminal equipment operating in the 1.5-1.7 GHz band. Transmitter linearity is not easily achieved at these frequencies, although high power (20W) class A/AB devices are becoming available. However, these components are expensive and require careful design to achieve a modest degree of linearity. In this paper an alternative approach to radio frequency (RF) power amplifier design for mobile satellite (MSAT) terminals using readily-available, power-efficient, and cheap class C devices in a feedback amplifier architecture is presented

Effect of prednisolone on inflammatory markers in pericardial tuberculosis: A pilot study

Background: Pericardial disorders are a common cause of heart disease, and the most common cause of pericarditis in developing countries is tuberculous (TB) pericarditis. It has been shown that prednisolone added to standard anti-TB therapy leads to a lower rate of constrictive pericarditis. We conducted a pilot study to evaluate the effect of adjunctive prednisolone treatment on the concentration of inflammatory markers in pericardial tuberculosis, in order to inform immunological mechanisms at the disease site. Methods: Pericardial fluid, plasma and saliva samples were collected from fourteen patients with pericardial tuberculosis, at multiple time points. Inflammatory markers were measured using multiplex luminex analysis and ELISA. Results: In samples from 14 patients we confirmed a strongly compartmentalized immune response at the disease site and found that prednisolone significantly reduced IL-6 concentrations in plasma by 8 hours of treatment, IL-1beta concentrations in saliva, as well as IL-8 concentrations in both pericardial fluid and saliva by 24 hours. Conclusion: Monitoring the early effect of adjunctive immunotherapy in plasma or saliva is a possibility in pericarditis

Development and Properties of the Adolescent Friendship Attachment Scale

Two studies are reported presenting the development of the Adolescent Friendship Attachment Scale (AFAS), a 30 item self-report measure of adolescent close friendship conceptualized as an attachment relationship. Study One reports the results of exploratory and confirmatory factor analyses with a sample of 490 adolescents aged 13 to 19 years. A second-order factor model was supported with a single friendship attachment factor underlying three first order factors (Secure, Anxious/Ambivalent, Avoidant) similar to those reported in the broader attachment literature. The AFAS subscales were found to be appropriately reliable and demonstrated appropriate convergent and discriminant validity when compared to measures of attachment styles (the Relationship Questionnaire) and parental and peer group attachment (the Inventory of Parent and Peer Attachment). Study Two reports a successful replication of the factor structure with an independent sample of 787 adolescents. Further research evaluating the predictive utility of the AFAS is recommended

Age and Sex Differences in the Influence of Attachment Relationships on Adolescent Psychological Health

The quality of adolescent attachment with mothers, fathers, and peers, and the impact of these relationships on psychological health and self-esteem is examined in a sample of 615 high school students. Using an attachment theory perspective, it is argued that different attachment relationships have different affects on adjustment depending on age and gender. Results support the view that attachment develops in peer relationships before withdrawing from parental relationships in adolescence and that this process occurs at different ages and has different consequences for self-esteem and depression. Maternal attachment had a greater impact on psychological adjustment for girls while paternal attachment had a greater impact for boys. It is concluded that while an attachment framework is useful for understanding developmental changes in relationship networks during adolescence, further individual difference and developmental factors may need to be considered

Intimacy and Attachment in Adolescent Relationships

From an attachment theory framework this study investigated the relationship of working models of self and other to the experience of intimacy conceptualised as a multidimensional phenomena. It was hypothesised that more self disclosure and increased intimacy goals would be associated with a positive model of other and that a positive model of self would be associated with greater levels of receiving disclosure and perceiving a partner to be responsive. Using a cross sectional sample of upper high school students (N=265) the results provided support for the view that the model of other primarily influences intimacy goals and self disclosure. Partial support was found for the effect of the model of self on eliciting disclosure from others and perceptions of partner responsiveness. The results are discussed in the context of multidimensional models of intimacy and adolescent psychosocial development

Adolescent Psychological Health and School Attitudes: The Impact of Attachment Relationships

The simultaneous and differential effects of parental, peer, and intimate friendship attachment on attitudes to school and psychological health were examined in a sample of 520 adolescents aged from 13 to 19 years. Based on recent extensions to attachment theory it was predicted that parental, peer and intimate friend attachment would impact on psychological health variables, while peer attachment and intimate friendship attachment along with depression and self-esteem would influence attitudes towards school. The hypothesised pattern of relationships was evaluated using structural equation modelling techniques. Overall, there was only partial support for the hypotheses. Results showed that parental attachment and peer attachment were related to psychological health but intimate friendship attachment was not. Intimate friendship was the only attachment variable that directly influenced school attitudes. The three attachment variables were only weakly inter-correlated. Implications with regard to extensions of attachment theory are discussed

Attachment Relationships and Adolescent Psychological Health: The Influence of Romantic Relationships

Research demonstrates that attachment relationships play important roles in adolescent psychological health. The influence of romantic relationships on adjustment is less clear. Using a cross-sectional sample of 515 adolescents, the current study examines whether romantic relationships replace the influence of other attachment relationships on adolescent psychological health. Regression analyses revealed that romantic relationships did not significantly impact on the influence of other attachment relationships when predicting depression but did significantly decrease the influence of peer attachment for self-esteem. It is concluded that romantic relationships during adolescence do not have major direct effects on adjustment and have only a minor influence on existing attachment relationships in predicting psychological health. Findings are discussed in the light of the continuity model of interpersonal relationships

There’s no apprenticeship for Alzheimer’s: The caring relationship when an older person experiencing dementia falls

© Cambridge University Press 2011Older people experiencing dementia are twice as likely to fall with consequences of serious injury, reduction in everyday activity, admission to long-term care and mortality. Carers of people with dementia are themselves at greater risk of physical and mental ill health, which increases as the dementia progresses. Unsurprisingly, carer burden also increases when a care-recipient falls. The aim of this study was to explore the experiences of falling of community-living older people with dementia and their carers. A qualitative approach was taken using interpretative phenomenological analysis. Nine older people with predominantly Alzheimer's disease and their ten carers were recruited from a large mental health National Health Service trust and participated in one-to-one and joint in-depth interviews. Three dyads participated in repeat interviews. Three focus groups were also carried out, with nine older people experiencing memory problems and 12 carers from a local Alzheimer's Society branch. The antecedents, falls events and consequences of falls were discussed. This paper reports specifically on the impact of falls on the caring relationship. Three themes emerged: ‘learning as you go’, ‘we're always together’, ‘nobody was interested’. The findings demonstrate how falling accentuates the impact of dementia on the dyad. Spouse-carers' discussion of their own falls emphasise the need for joint assessment of health and wellbeing to reduce carer burden and preserve the couplehood of the dyad.The South West London NHS Mental Health Care Trust which part-funded this researc

Psychological Health, Maternal Attachment and Attachment Style in Breast and Formula Feeding Mothers: A Preliminary Study.

This study examined psychological health, maternal attachment, and attachment style in an Australian sample of breast and formula feeding mothers. Thirty-six breast feeding and twenty-four formula feeding women with a child between four and six months of age were recruited through community health centres and snowball sampling. Participation involved a thirty-minute interview and completion of relevant questionnaires. Contrary to expectations, no differences were found between breast and formula feeding mothers in terms of their psychological health and maternal attachment. Results suggest that secure attachment styles are related to greater psychological health and that they predict the likelihood of a mother changing feeding method. The results of this study challenge widely held assumptions concerning the importance of breast feeding for maternal wellbeing and attachment with infants, and support the literature suggesting attachment styles play an important role in affect regulation and the adjustment to new motherhood