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We generalize a theorem of Groves and Kochloukova concerning cohomological finiteness conditions for metabelian groups in order to encompass a classical example of Baumslag and Stammbach.

The link between greater wellbeing and longevity is well documented. The aim of the current study was to test whether this association is consistent across individualistic and collectivistic cultures. The sample consisted of 13,596 participants from 11 European countries, each of which was assigned an individualism score according to Hofstede et al.'s (Cultures and organizations: software of the mind, McGraw Hill, New York, 2010) cultural dimension of individualism. We tested whether individualism moderated the cross-sectional association between wellbeing and self-rated health or the longitudinal association between wellbeing and mortality risk. Our analysis revealed a significant interaction between individualism and wellbeing such that the association between wellbeing and self-rated health or risk of mortality from cardiovascular disease was stronger in more individualistic countries. However, the interaction between wellbeing and individualism was not significant in analysis predicting all-cause mortality. Further prospective studies are needed to confirm our finding and to explore the factors responsible for this culturally dependent effect. Electronic supplementary material The online version of this article (doi:10.1007/s10865-017-9871-x) contains supplementary material, which is available to authorized users.

Sensitising erbium doped fibres with ytterbium significantly relaxes constraints in pump wavelength and device length. This makes versatile compact lasers and optical amplifiers operating at the important telecommunications window of 1.5µm a reality.

Purpose: This paper examines the connection between shareholdings by different groups of corporate insiders and market valuation in South Africa using a sample of 169 listed corporations from 2002 to 2007. Design/methodology/approach: We distinctively employ fixed-effects and two-stage least squares regressions to uniquely examine the effect of shareholdings by employees, chief executive officers, chief financial officers, other executive directors and non-executive directors on market valuation. Findings: We find that aggregate ownership by all corporate insiders have a positive effect on market valuation. However, when we examine the link between ownership by individual groups of corporate insiders and market valuation, our results suggest that firms with higher ownership by chief executive officers and other executive directors have lower market valuation, but we do not find any evidence that ownership by chief financial officers has any significant effect on market valuation. In contrast, we find that ownership by employees and non-executive directors has a positive effect on market valuation. Originality/value: Past studies have mostly examined the association between aggregate insider ownership and market valuation. By contrast, there is an acute dearth of evidence on how ownership by different insider groups influences market valuation. Our evidence contributes to the literature by providing evidence on how ownership by different insider groups affects market evaluation. We also innovatively apply a number of econometric models that sufficiently address different types of endogeneities and market valuation measures. Article type: Research paper

We report a novel method to increase the UV photosensitivity of GeO2:SiO2 optical fibers based on exposure to CO2 laser irradiation before grating writing. Fibers treated with a CO2 laser can produce gratings with refractive-index modulation two times greater and a Bragg wavelength that can be 2 nm longer than those of untreated fibers. Experiments on GeO2:SiO2 preform samples treated with a CO2 laser in a way similar to the fibers showed a marked increase of the 242 nm absorption band, which is associated with an increase of germanium oxygen-deficient centers and is believed to be responsible for the higher photorefractive response.

In recent decades two broad but distinguishable approaches to language teacher development have predominated: an informing approach based largely on the transmission of principles of new theory and method; and a responsive approach centering on teachers’ understanding of their own practice. Our study offers the notion of the Idea, as an element of input that can inspire teachers and be appropriated for their own practice, as a means of synthesising the two traditions. Evidence that teacher learning operates at the level of the Idea is presented on the basis of literature, and also from two case studies which examine teacher learning across different language teacher language learning contexts. Based on the observations of the case studies, the paper offers a fully useable characterisation of the Idea, offering the notion as a crucial concept for language teacher development.

The magnetic properties of Pr2Co17-x Al-x and Y2Co17-xAlx compounds with 0 less than or equal to x less than or equal to 4 were studied by means of magnetic measurements. These measurements have shown that increasing Al concentration leads to a sign reversal of the magnetocrystalline Co-sublattice anisotropy from easy-plane anisotropy for low Al concentration to easy-axis anisotropy for higher Al concentration. In the Pr2Co17-xAlx compounds, the competition between the Pr-and Co-sublattice anisotropies leads to spin-reorientation transitions at temperatures that decrease strongly with increasing Al concentration. There is an almost linear decrease of the Curie temperature with Al concentration. Also the saturation moments at 5 K decrease strongly with Al concentration although this decrease is less strong in Pr2Co17-xAlx than in Y2Co17-xAlx. (C) 1997 Elsevier Science S.A.

The study of properties and of processes in materials, frequently hinges upon understanding phenomena which originate at the atomic level. In such cases the accurate description of the interactions between large numbers of atoms is critical and in turn requires the accurate description of the electrons which play a crucial role in the bonding of atoms into molecules, surfaces and solids. This can only be achieved by solving the equations of quantum mechanics. These equations are too complicated to solve exactly; however their solutions can be approximated by computational techniques. The most accurate ? but also most computationally demanding ? are the “ab initio” techniques which do not use any empirical adjustable parameters. Amongst them, the Density Functional Theory (DFT) formulation of quantum mechanics stands out as an excellent compromise between accuracy and computational efficiency. However, the applicability of ab initio techniques is severely limited by poor scaling: the computational effort needed to perform an ab initio calculation increases with (at least) the third power of the number of atoms, N. This cubic-scaling bottleneck limits the number of atoms we can study to a few hundred at most, even on parallel supercomputers. To overcome this length-scale limitation, a number of researchers worldwide have been pioneering the development of a novel class of ab initio methods with linear-scaling or “Order N” (O(N)) computational cost which nevertheless retain the same high level of accuracy as the conventional approaches. While physically motivated, such methods have proved particularly hard to develop as they introduce highly non-trivial localisation constraints. Nevertheless, many major obstacles have been overcome and a number of O(N) methods (SIESTA, CONQUEST, ONETEP, etc.) for ground state DFT calculations on systems with a gap (e.g. molecules, semiconductors and insulators) are now available and have reached a state of maturity that allows them to be used to study ”real” materials. The particular focus of this workshop is therefore to look forward to what can be achieved in the next few years. Our aim is twofold: (1) As O(N) methods are currently extending the applicability of DFT calculations to problems involving biomolecules and nanostructures they are leading to completely new levels of understanding of these systems. This CECAM meeting will give us the opportunity to make an appraisal of such large-scale simulations and their potential to connect more directly to experiments. (2) We also want to examine the options for extending linear-scaling to problems that cannot be treated by ground-state DFT but require other, more complex approaches. These include methods for treating metallic systems, excited states and wavefunction-based theories for including electronic correlation. Finding ways to transform these methods to linear-scaling cost, and hence extent their applicability to the nano-scale, is the next big challenge that the community of developers of large-scale electronic structure methods is beginning to face. We hope that this workshop will stimulate these major new O(N) methodological developments by bringing together the leading groups in the development of O(N) DFT methods with the leading groups in the development of metal and excited-state or wavefunction-based methods. Strong emphasis during the workshop will be given to discussion in order to promote the exchange of ideas between different communities (Physics, Chemistry, Materials Science, Biochemistry) which are all interested in large-scale applications with ab initio accuracy but are approaching them from different perspectives.

Abstract\ud Aims Rhizodeposits collected from hydroponic solutions with roots of maize and barley, and seed mucilage washed from chia, were added to soil to measure their impact on water retention and hysteresis in a sandy loam soil at a range of concentrations. We test the hypothesis that the effect of plant exudates and mucilages on hydraulic properties of soils depend on their physicochemical characteristics and origin.\ud Methods Surface tension and viscosity of the exudate solutions were measured using the Du Noüy ring method and a cone-plate rheometer, respectively. The contact angle of water on exudate treated soil was measured with the sessile drop method. Water retention and hysteresis were measured by equilibrating soil samples, treated with exudates and mucilages at 0.46 and 4.6 mg g−1 concentration, on dialysis tubing filled with polyethylene glycol (PEG) solution of known osmotic potential.\ud Results Surface tension decreased and viscosity increased with increasing concentration of the exudates and mucilage in solutions. Change in surface tension and viscosity was greatest for chia seed exudate and least for barley root exudate. Contact angle increased with increasing maize root and chia seed exudate concentration in soil, but not barley root. Chia seed mucilage and maize root rhizodeposits enhanced soil water retention and increased hysteresis index, whereas barley root rhizodeposits decreased soil water retention and the hysteresis effect. The impact of exudates and mucilages on soil water retention almost ceased when approaching the wilting point at −1500 kPa matric potential.\ud Conclusions Barley rhizodeposits behaved as surfactants, drying the rhizosphere at smaller suctions. Chia seed mucilage and maize root rhizodeposits behaved as hydrogels that hold more water in the rhizosphere, but with slower rewetting and greater hysteresis.

This thesis is concerned with sound minimisation in space and frequency for local studies have been performed to develop methods of active control. designing larger zones of quiet than are obtained with conventional systems, while a comprehensive study of a practical active headrest system was performed with the aim of improving its performance. A general formulation for 2-norm and oo-norm sound minimisation over a space is described, which in contrast to conventional approaches, which use pressure or pressure and particle velocity cancellation at one point, has no cancellation points within the minimisation region. This method therefore provides the best overall attenuation of sound within the space due to the optimal design. The performance of the sound minimisation method for local active control has been evaluated in this work using computer simulations. Larger zones of quiet were achieved compared with conventional methods for two or three secondary sources. These new design methods could be applied to a practical application, such as a headrest system. The methods described above are then extended to active control of broadband noise. This involves the acoustic pressure minimisation over both space and frequency. The perfoiTnance was investigated through computer simulations, and the results showed that good attenuation could be achieved at desired regions over both space and frequency. These methods could be realised in practice by using virtual microphones to estimate the pressure fields away from the position of the microphones. Hz and H2/H0. methods for designing feedback controllers have also been presented, and implemented in an active headrest system which used single channel feedback controllers to attenuate the noise at a virtual microphone. This is the Orst time that real-time virtual microphone feedback controllers have been implemented in an active headrest system. The theoretical and practical stability and performance issues of the active headrest system have also been investigated in this work. The results showed that good performance could only be achieved with unstable open-loop controllers due to the reduced magnitude of the virtual plant response. This novel analysis could provide guidelines to designing better performing active headrest systems. The performance of an active headrest system has also been evaluated in a realistic environment to predict performance in a passenger aircraft.