Amplitude-modulation characteristics of power-combining Class-E amplifier with finite choke

Power back-off performances of a new variant power-combining Class-E amplifier under different amplitude-modulation schemes such as continuous wave (CW), envelope elimination and restoration (EER), envelope tracking (ET) and outphasing are for the first time investigated in this study. Finite DC-feed inductances rather than massive RF chokes as used in the classic single-ended Class-E power amplifier (PA) resulted from the approximate yet effective frequency-domain circuit analysis provide the wherewithal to increase modulation bandwidth up to 80% higher than the classic single-ended Class-E PA. This increased modulation bandwidth is required for the linearity improvement in the EER/ET transmitters. The modified output load network of the power-combining Class-E amplifier adopting three-harmonic terminations technique relaxes the design specifications for the additional filtering block typically required at the output stage of the transmitter chain. Qualitative agreements between simulation and measurement results for all four schemes were achieved where the ET technique was proven superior to the other schemes. When the PA is 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 12 dB peak-to-average power ratio. © 2011 The Institution of Engineering and Technology.

"From Indomania to Indophobia":Thomas De Quincey's Providential Orientalism

Thomas De Quincey’s terrifying oriental nightmares, reported to sensational acclaim in his Confessions of an English Opium-Eater (1821), have become a touchstone of romantic imperialism in recent studies of the literature of the period (Leask 1991; Barrell 1992 et al). De Quincey’s collocation of “all creatures, birds, beasts, reptiles, all trees and plants, usages and appearances, that are found in all tropical regions” in the hypnagogic hallucinations that characterized what he called “the pains of opium” seems to anticipate neatly Said’s theory of orientalism, whereby the orient was supplied by the west with “a mentality, a genealogy, an atmosphere,” the attitudinal basis as he argues for the continuing march of imperialism from the late eighteenth century. Yet, as Thomas Trautmann (1997) has pointed out, orientalist scholarship based in India and led by the influential Asiatic Society of Bengal in the late eighteenth century was extremely enthusiastic about Indian classical antiquity. The early orientalist scholarship posited ethnic, linguistic, cultural and religious links between Europe and India, while recognizing the greater antiquity of Indian civilization. This favourable attitude (which Trautmann calls “Indomania”) was overtaken in the nineteenth century by disavowal of that scholarship and repugnance (which he calls “Indophobia”), influenced by utilitarian and evangelical attitudes to colonialism. De Quincey’s lifespan covers this crucial period of change. My paper examines his evangelical upbringing and interest in biblical and orientalist scholarship to suggest his anxious investment in these modes of thinking. I will suggest that the bizarre orientalist fusions of his dreams can be better understood in the context of changing attitudes to the imperialism during the period. An examination of his work provides a far more dynamic understanding of the processes of orientalism than the binary model suggested by Said. The transformation implied from imperial scholarship to governance, I will suggest, is not irrelevant to a world which continues to pull apart on various grounds of race and ethnicity, and reflects on our own role in the academy today.

Spectroscopic Observations of SN 2012fr: A Luminous Normal Type Ia Supernova with Early High Velocity Features and Late Velocity Plateau

We present 65 optical spectra of the Type Ia supernova SN 2012fr, of which 33 were obtained before maximum light. At early times SN 2012fr shows clear evidence of a high-velocity feature (HVF) in the Si II 6355 line which can be cleanly decoupled from the lower velocity "photospheric" component. This Si II 6355 HVF fades by phase -5; subsequently, the photospheric component exhibits a very narrow velocity width and remains at a nearly constant velocity of v~12,000 km/s until at least 5 weeks after maximum brightness. The Ca II infrared (IR) triplet exhibits similar evidence for both a photospheric component at v~12,000 km/s with narrow line width and long velocity plateau, as well as a high-velocity component beginning at v~31,000 km/s two weeks before maximum. SN 2012fr resides on the border between the "shallow silicon" and "core-normal" subclasses in the Branch et al. (2009) classification scheme, and on the border between normal and "high-velocity" SNe Ia in the Wang et al. (2009a) system. Though it is a clear member of the "low velocity gradient" (LVG; Benetii et al., 2005) group of SNe Ia and exhibits a very slow light-curve decline, it shows key dissimilarities with the overluminous SN 1991T or SN 1999aa subclasses of SNe Ia. SN 2012fr represents a well-observed SN Ia at the luminous end of the normal SN Ia distribution, and a key transitional event between nominal spectroscopic subclasses of SNe Ia.

ESO observations of the Nucleus of Rosetta Target 67P/C-G

Rosetta is ESA's new comet orbiter mission, launched in March 2004 and currently en route to Jupiter-family comet 67P/Churyumov-Gerasimenko. The probe will rendezvous with the comet in 2014 and remain in orbit around the nucleus for on-going detailed physical and compositional analysis. Pre-encounter observations of the target are important for characterization of the heliocentric light-curve behaviour and the physical properties of the nucleus, information that is critical for mission planning. The nucleus was first characterized using HST observations in 2003 (Lamy et al. 2006) and observed directly in May 2005 by ground based telescopes (Lowry et al. 2006) when it was at 5.6 AU from the Sun. An extensive database of nucleus observations have since been acquired, not only from large ground-based telescopes like the ESO VLT (Tubiana et al. 2008 & 2011), but also from Spitzer (Kelley et al. 2006 & 2009; Lamy et al. 2008).

Unlock the Pain: Exercise is the Key

Back pain is a common complaint in pregnancy, affecting approximately two-thirds of pregnant women [Pennick and Lidle, 2013]. This can lead to increased disability, affecting daily activities and cause absence from work. Evidence-based recommendations can be made for the use of exercise as an effective conservative treatment for the relief of back pain in pregnancy [Benten et al, 2014]. This poster explores the background to back pain in pregnancy and the advice women should be offered in relation to exercise to help normalise their pregnancy experience and enhance wellbeing.

Chronology of the site of Grotte du Renne, Arcy-sur-Cure, France: implications for Neanderthal symbolic behaviour

Higham et al (2010) published a large series of new dates from the key French Palaeolithic site of the Grotte du Renne at Arcy-sur-Cure. The site is important because it is one of only two sites in Europe in which Châtelperronian lithic remains co-occur with Neanderthal human remains. A large series of dates from the Mousterian, Châtelperronian, Aurignacian and Gravettian levels of the site was obtained. The 14C results showed great variability, which Higham et al (2010) interpreted as most likely to be due to mixing of archaeological material in the site. In contrast, Caron et al (2011) suggested that the site stratigraphy is well preserved and that the problem with the variability in the radiocarbon ages was due to unremoved contamination in the dated bone. In this paper we address their critique of the original Higham et al (2010) paper