Power-Combining Class-E Amplifier With Finite Choke

A recently introduced power-combining scheme for a Class-E amplifier is, for the first time, experimentally validated in this paper. A small value choke of 2.2 nH was used to substitute for the massive dc-feed inductance required in the classic Class-E circuit. The power-combining amplifier presented, which operates from a 3.2-V dc supply voltage, is shown to be able to deliver a 24-dBm output power and a 9.5-dB gain, with 64% drain efficiency and 57% power-added efficiency at 2.4 GHz. The power amplifier exhibits a 350-MHz bandwidth within which a drain efficiency that is better than 60% and an output power that is higher than 22 dBm were measured. In addition, by adopting three-harmonic termination strategy, excellent second-and third-harmonic suppression levels of 50 and 46 dBc, respectively, were obtained. The complete design cycle from analysis through fabrication to characterization is explained. © 2010 IEEE.

Will attracting the creative class boost economic growth in old industrial regions? A case study of Scotland

Attracting in-migration of the creative class has been argued by Florida (2002) to be a route to higher economic growth in the era of the knowledge economy. This paper critically evaluates this proposition in relation to old industrial regions using the example of Scotland. The paper presents an assessment of, in the first instance, to what extent there is a shortage of skilled, talented and entrepreneurial individuals and, in the second instance, whether a talent attraction strategy alone can hope to attract such people to Scotland. It is proposed that for most migrants the availability of appropriate economic opportunities is a prerequisite for mobility. However, despite uncertain evidence that place attractiveness is a catalyst to mobility among the so-called creative class, this is not a reason for dismissing talent attraction programmes. Instead it is argued that talent attraction programmes have the potential to contribute to old industrial economies, but their success will be greatest when talent attraction is carefully targeted and based on economic realities rather than the marketing of ethereal conceptions of place attractiveness.

Rigorous conditions for food-web intervality in high-dimensional trophic niche spaces

Food webs represent trophic (feeding) interactions in ecosystems. Since the late 1970s, it has been recognized that food-webs have a surprisingly close relationship to interval graphs. One interpretation of food-web intervality is that trophic niche space is low-dimensional, meaning that the trophic character of a species can be expressed by a single or at most a few quantitative traits. In a companion paper we demonstrated, by simulating a minimal food-web model, that food webs are also expected to be interval when niche-space is high-dimensional. Here we characterize the fundamental mechanisms underlying this phenomenon by proving a set of rigorous conditions for food-web intervality in high-dimensional niche spaces. Our results apply to a large class of food-web models, including the special case previously studied numerically.

Diving behaviour during the internesting interval for loggerhead turtles Caretta caretta nesting in Cyprus

Time depth recorders were used to assess the patterns of depth utilisation by 2 loggerhead turtles Caretta caretta in Cyprus, eastern Mediterranean. Dives to the seabed accounted for 59 % (171 h) and 75 % (215 h) of the internesting interval, respectively, with most dives being shallow (

Long-term occlusal and soft-tissue profile outcomes after treatment of Class II Division 1 malocclusion with fixed appliances

Introduction: Our objective was to determine which factors were predictive of good long-term outcomes after fixed appliance treatment of Class II Division 1 malocclusion. Methods: Two hundred seven patients with Class II Division 1 malocclusion were examined in early adulthood at a mean of 4.6 years after treatment with fixed appliances. The peer assessment rating index was used to evaluate dental alignment and occlusal relationships. The soft-tissue profile was assessed with the Holdaway angle. Results: Logistic regression identified 3 pretreatment variables that were predictive of a good facial profile (Holdaway angle) at recall: the lower lip to E-plane distance (P

Limnonectins: A new class of antimicrobial peptides from the skin secretion of the Fujian large-headed frog (Limnonectes fujianensis)

Amphibian skin secretions are rich sources of biologically-active peptides with antimicrobial peptides predominating in many species. Several studies involving molecular cloning of biosynthetic precursor-encoding cDNAs from skin or skin secretions have revealed that these exhibit highly-conserved domain architectures with an unusually high degree of conserved nucleotide and resultant amino acid sequences within the signal peptides. This high degree of nucleotide sequence conservation has permitted the design of primers complementary to such sites facilitating “shotgun” cloning of skin or skin secretion-derived cDNA libraries from hitherto unstudied species. Here we have used such an approach using a skin secretion-derived cDNA library from an unstudied species of Chinese frog – the Fujian large-headed frog, Limnonectes fujianensis – and have discovered two 16-mer peptides of novel primary structures, named limnonectin-1Fa (SFPFFPPGICKRLKRC) and limnonectin-1Fb (SFHVFPPWMCKSLKKC), that represent the prototypes of a new class of amphibian skin antimicrobial peptide. Unusually these limnonectins display activity only against a Gram-negative bacterium (MICs of 35 and 70 µM) and are devoid of haemolytic activity at concentrations up to 160 µM. Thus the “shotgun” cloning approach described can exploit the unusually high degree of nucleotide conservation in signal peptide-encoding domains of amphibian defensive skin secretion peptide precursor-encoding cDNAs to rapidly expedite the discovery of novel and functional defensive peptides in a manner that circumvents specimen sacrifice without compromising robustness of data

Biaryl polyamides as a new class of DNA quadruplex-binding ligands

We report a novel class of biaryl polyamides highly selective for G-quadruplex DNA, and with significant cytotoxicity in several cancer cell lines; they form planar U-shaped structures that match the surface area dimensions of a terminal G-quartet in quadruplex structures rather than the grooves of duplex DNA.

Tetra-end-linked oligonucleotides forming DNA G-quadruplexes: a new class of aptamers showing anti-HIV activity.

The biophysical and biological properties of unprecedented anti-HIV aptamers are presented. The most active aptamer (1L) shows a significant affinity to the HIV protein gp120.

Analysis and Design of Class-E3F and Transmission-Line Class-E3F2 Power Amplifiers

In this paper, analysis and synthesis approach for two new variants within the Class-EF power amplifier (PA) family is elaborated. These amplifiers are classified here as Class-E3 F2 and transmission-line (TL) Class-E3 F 2. The proposed circuits offer means to alleviate some of the major issues faced by existing topologies such as substantial power losses due to the parasitic resistance of the large inductor in the Class-EF load network and deviation from ideal Class-EF operation due to the effect of device output inductance at high frequencies. Both lumped-element and transmission-line load networks for the Class-E 3 F PA are described. The load networks of the Class-E3 F and TL Class-E 3 F2amplifier topologies developed in this paper simultaneously satisfy the Class-EF optimum impedance requirements at fundamental frequency, second, and third harmonics as well as simultaneously providing matching to the circuit optimum load resistance for any prescribed system load resistance. Optimum circuit component values are analytically derived and validated by harmonic balance simulations. Trade-offs between circuit figures of merit and component values with some practical limitations being considered are discussed. © 2010 IEEE.