Power back-off behaviour of high-efficiency power-combining Class-E amplifier

Power back-off performances of the modified power-combining Class-E amplifier under different amplitudemodulation schemes such as envelope elimination and restoration (EER) and envelope tracking (ET) are experimentally assessed in this paper. The modified output load network adopting three-harmonic terminations technique eliminates the need for additional lossy filtering section in the transmitter chain. Small dc-feed inductances rather than massive RF chokes as in the classic Class-E amplifier are used so as to increase the modulation bandwidth and therefore improve the linearity of the EER transmitter. High efficiency over a wide dynamic range using amplitude modulation through drain-voltage control (EER) was achieved and this agrees well with the Class-E theoretical prediction. When the PA was used within the ET scheme, an increase of average drain efficiency of as high as 40% with respect to the CW excitation was obtained for a multi-carrier input signal with 12dB peak-to-average power ratio. © 2011 Institut fur Mikrowellen.

Light curves for off-centre ignition models of Type Ia supernovae

Motivated by recent models involving off-centre ignition of Type Ia supernova explosions, we undertake three-dimensional time-dependent radiation transport simulations to investigate the range of bolometric light-curve properties that could be observed from supernovae in which there is a lop-sided distribution of the products from nuclear burning. We consider both a grid of artificial toy models which illustrate the conceivable range of effects and a recent three-dimensional hydrodynamical explosion model. We find that observationally significant viewing angle effects are likely to arise in such supernovae and that these may have important ramifications for the interpretation of the observed diversity of Type Ia supernova and the systematic uncertainties which relate to their use as standard candles in contemporary cosmology. © 2007 RAS.

Off-center explosions of Chandrasekhar-mass white dwarfs:An explanation of super-bright type la supernovae?

Context. The recent discovery of a very bright type la supernova, SNLS-03D3bb (=SN 2003fg), in the Supernova Legacy Survey (SNLS) has raised the question of whether super-Chandrasekhar-mass white-dwarf stars are needed to explain such bright explosions. Progenitors of this sort could form by mergers of pairs of rather massive white dwarfs. Binary systems of two white dwarfs in close orbit, where their total mass significantly exceeds the Chandrasekhar mass, have not yet been found. Therefore SNLS-03D3bb could establish the first clear case of a double-degenerate progenitor of a (peculiar) type la supernovae. Moreover, if this interpretation is correct, it casts some doubt on the universality of the calibration relations used to make SNe la distance indicators for cosmology. Aims. We aim to evaluate the case for a super-Chandrasekhar-mass progenitor for SNLS-03D3bb in light of previous theoretical work on super-Chandrasekhar-mass explosions. Furthermore, we propose an alternative scenario involving only a Chandrasekhar-mass progenitor. Methods. We present a theoretically motivated critical discussion of the expected observational fingerprints of super-Chandrasekharmass explosions. As an alternative, we describe a simple class of aspherical Chandrasekhar-mass models in which the products of nuclear burning are displaced from the center. We then perform simple radiative transfer calculations to predict synthetic lightcurves for one such off-center explosion model. Results. In important respects, the expected observational consequences of super-Chandrasekhar-mass explosions are not consistent with the observations of SNLS-03D3bb. We demonstrate that the lopsided explosion of a Chandrasekhar-mass white dwarf could provide a better explanation. © ESO 2007.

A direct physiological trade-off between personal and social immunity

1. Recent work shows that organisms possess two strategies of immune response: personal immunity, which defends an individual, and social immunity, which protects other individuals, such as kin. However, it is unclear how individuals divide their limited resources between protecting themselves and protecting others.
2. Here, with experiments on female burying beetles, we challenged the personal immune system and measured subsequent investment in social immunity (antibacterial activity of the anal exudates).
3. Our results show that increased investment in one aspect of personal immunity (wound repair) causes a temporary decrease in one aspect of the social immune response.
4. Our experiments further show that by balancing investment in personal and social immunity in this way during one breeding attempt, females are able to defend their subsequent lifetime reproductive success.
5. We discuss the nature of the physiological trade-off between personal and social immunity in species that differ in the degree of eusociality and coloniality, and suggest that it may also vary within species in relation to age and partner contributions to social immunity.

Life-Cycle Energy Analysis of a Modular/Off-Site Building School

This paper is concerned with assessing the building’s the energy efficiency and qualities of a modular design for the education industry, in order assess the long economic benefits. The research includes a life-cycle energy and cost analysis of the school building design, predicting the impact on the operational cost of the building as a result of the addition of photovoltaic panels. The paper also includes a comparative study between the ECO Modular Solutions building, and a current standard prefabricated school building, quantifying the savings in CO2 emissions and savings in cost.

A Preliminary Qualitative Investigation of Voice Hearing and Its Association with Dissociation in Chronic PTSD

Following on from a quantitative study, this research used a qualitative methodology to investigate the lived experience of 3 men with chronic posttraumatic stress disorder associated with the conflict in Northern Ireland who reported auditory hallucinations. Data analysis used the Framework method. Results showed that beliefs about voices, dissociation of identity and body, and interpersonal impact were central superordinate themes associated with auditory hallucinations in posttraumatic stress disorder. Central subordinate themes included feeling a lack of controllability over voices, experiencing them as ego-dystonic, and feeling an increased sense of isolation and shame because of their presence. Results provide an in-depth analysis of participants' lived experiences and enhance understanding of previous quantitative findings.

An Exploratory Analysis of Voice Hearing in Chronic PTSD: Potential Associated Mechanisms

This research investigated auditory hallucinations (AH) in a sample with chronic posttraumatic stress disorder (PTSD) and examined dissociation and thought suppression as potential associated mechanisms. In all, 40 individuals with PTSD were assessed on the hallucinations subscale of the Positive and Negative Syndrome Scale and on measures of dissociation and thought suppression. Half of the sample reported AH (n = 20, 50%). Those reporting AH had higher general and pathological dissociation scores but did not differ on thought suppression or PTSD symptom severity. Results suggest that (a) AH in chronic PTSD is not a rare phenomenon, (b) dissociation is significantly related to AH, and (c) dissociation may be a potential mediating mechanism for AH in PTSD.

Sex, Politics and Religion: The Transformation of the Figure of the Fairy Queen from Thomas off Ersseldoune to ‘‘Thomas Rymer’’

Our earliest version of the Thomas Rymer story is the medieval romance Thomas off Ersseldoune (c.1430). There is a four hundred year lacuna before the ballad “Thomas Rymer”, our next surviving version, is recorded in the early 1800s. In the intervening time the narrative changed very little but the dynamic of the piece, radically. The romance transformed into the highly subversive ballad, “Thomas Rymer”. Central to this transformation is the reconceptualization of the romance's heroine. Referred to simply as the “lufly lady” and caught between her husband, the fay King, and a mere mortal, Thomas, she becomes in the ballad the powerful Queen of the Fairies. The ballad is structured around a series of revelations in which the enigmatic Queen assumes the roles of Eve and Mary, and finally Christ Himself. I will explore the implications of this extraordinary ballad. Moreover, I suggest that it is Queen Elizabeth herself who, ironically, enables the heroine's transformation. “Ironically” because it appears that it was Elizabeth's own restrictions, designed to suppress heretical, seditious or radical literature, which forced Thomas off Ersseldoune (and many other romances which employed religious imagery or figures) out of the written domain and into the oral tradition. And yet, it is Elizabeth who, in creating the image of herself as a female prince, as the Faerie Queen, inspires a new literary vocabulary designed to describe female executive power, without which it would have been impossible to imagine a figure such as the ballad's Queen of the Fairies.

Trading off dietary choices, physical exercise and cardiovascular disease risks

Despite several decades of decline, cardiovascular diseases are still the most common causes of death in Western societies. Sedentary living and high fat diets contribute to the prevalence of cardiovascular diseases. This paper analyses the trade-offs between lifestyle choices defined in terms of diet, physical activity, cost, and risk of cardiovascular disease that a representative sample of the population of Northern Ireland aged 40-65 are willing to make. Using computer assisted personal interviews, we survey 493 individuals at their homes using a Discrete Choice Experiment (DCE) questionnaire administered between February and July 2011 in Northern Ireland. Unlike most DCE studies for valuing public health programs, this questionnaire uses a tailored exercise, based on the individuals’ baseline choices. A “fat screener” module in the questionnaire links personal cardiovascular disease risk to each specific choice set in terms of dietary constituents. Individuals are informed about their real status quo risk of a fatal cardiovascular event, based on an initial set of health questions. Thus, actual risks, real diet and exercise choices are the elements that constitute the choice task. Our results show that our respondents are willing to pay for reducing mortality risk and, more importantly, are willing to change physical exercise and dietary behaviours. In particular, we find that to improve their lifestyles, overweight and obese people would be more likely to do more physical activity than to change their diets. Therefore, public policies aimed to target obesity and its related illnesses in Northern Ireland should invest public money in promoting physical activity rather than healthier diets.

Patterning employee voice in multinational companies

Employee voice has been an enduring theme within the employment relations literature.This article profiles the incidence of a range of direct and indirect employee voice mechanisms within multinational companies (MNCs) and, using an analytical framework, identifies a number of different approaches to employee voice. Drawing from a highly representative sample of MNCs in Ireland, we point to quite a significant level of engagement with all types of employee voice, both direct and indirect. Using the analytical framework, we find that the most common approach to employee voice was an indirect voice approach (i.e. the use of trade unions and/or non-union structures of collective employee representation). The regression analysis identifies factors such as country of origin, sector, the European Union Directive on Information and Consultation and date of establishment as having varying impacts on the approaches adopted by MNCs to employee voice. © The Author(s) 2010.

The impact of union presence and strategic human resource management on employee voice in multinational enterprises in Australia

In this article, we examine the use and character of employee voice mechanisms of foreign-owned multinational enterprises operating in Australia, as well as the influence of a strategic human resource management approach and union presence. Findings indicate that foreign-owned multinational enterprises are high-level users of the full range of employee voice mechanisms, with the exceptions of use of employee suggestion schemes, trade union recognition and the use of joint consultation committees across all sites. Using logistic regression analysis, findings show that trade union presence, a strategic human resource management approach, greenfield site and country of origin impact the employee voice approach adopted. High trade union presence is associated with an indirect employee voice approach. A low trade union presence is associated with a direct or a minimalist approach to employee voice. Moreover, a strategic human resource management approach is associated with both direct and dualistic approaches to employee voice. Implications are drawn for theory and practice. © Australian Labour and Employment Relations Association (ALERA) SAGE Publications Ltd, Los Angeles, London, New Delhi, Singapore and Washington DC.