27 resultados para Equation on groups
em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast
Resumo:
In this paper we describe the design of a parallel solution of the inhomogeneous Schrodinger equation, which arises in the construction of continuum orbitals in the R-matrix theory of atomic continuum processes. A prototype system is described which has been programmed in occam2 and implemented on a bi-directional pipeline of transputers. Some timing results for the prototype system are presented, and the development of a full production system is discussed.
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We consider a prototypical dynamical lattice model, namely, the discrete nonlinear Schrodinger equation on nonsquare lattice geometries. We present a systematic classification of the solutions that arise in principal six-lattice-site and three-lattice-site contours in the form of both discrete multipole solitons and discrete vortices. Additionally to identifying the possible states, we analytically track their linear stability both qualitatively and quantitatively. We find that among the six-site configurations, the
Resumo:
Source: PROCEEDINGS OF THE ROYAL SOCIETY OF EDINBURGH SECTION A-MATHEMATICS Volume: 131 Pages: 1257-1273 Part: Part 6 Published: 2001 Times Cited: 5 References: 23 Citation MapCitation Map beta Abstract: We show that the Banach space M of regular sigma-additive finite Borel complex-valued measures on a non-discrete locally compact Hausdorff topological Abelian group is the direct sum of two linear closed subspaces M-D and M-ND, where M-D is the set of measures mu is an element of M whose Fourier transform vanishes at infinity and M-ND is the set of measures mu is an element of M such that nu is not an element of MD for any nu is an element of M \ {0} absolutely continuous with respect to the variation \mu\. For any corresponding decomposition mu = mu(D) + mu(ND) (mu(D) is an element of M-D and mu(ND) is an element of M-ND) there exist a Borel set A = A(mu) such that mu(D) is the restriction of mu to A, therefore the measures mu(D) and mu(ND) are singular with respect to each other. The measures mu(D) and mu(ND) are real if mu is real and positive if mu is positive. In the case of singular continuous measures we have a refinement of Jordan's decomposition theorem. We provide series of examples of different behaviour of convolutions of measures from M-D and M-ND.
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In this article the authors discuss the usefulness of focus groups for researching sensitive issues using evidence from a study examining the experiences of nurses providing care in the context of the Northern Ireland Troubles. They conducted three group interviews with nurses during which they asked about the issues the nurses face(d) in providing nursing care amid enduring social division. Through a discursive analysis of within-group interaction, they demonstrate how participants employ a range of interpretive resources, the effect of which is to prioritize particular knowledge concerning the nature of nursing care. The identification of such patterned activity highlights the ethnographic value of focus groups to reveal social conventions guiding the production of accounts but also suggests that accounts cannot be divorced from the circumstances of their production. Consequently, the authors argue that focus groups should be considered most useful for illuminating locally sanctioned ways of talking about sensitive issues.
Resumo:
This experiment investigated the effect of providing access to straw in racks on the welfare of sows in large dynamic groups. Two treatments were applied: (1) access to two racks containing chopped barley straw (offering an average of 0.3 kg straw/sow/day) and (2) control, with no straw racks. Treatments were applied to two separate dynamic groups each containing 35 ( 3) sows. Approximately 9 sows were replaced in each of these groups at 3-week intervals (each replacement constituting a replicate of the study). Peak rack usage was shown between 08:00 and 12:00 h, where on average 6% of sows were observed at each rack. On average over a 24-h period, 27% of sows that were observed at the racks were newly introduced. This percentage was significantly greater in the pre- rather than post-feeding yard (P 0.05). A greater proportion of sows performed sham chewing behaviour in the post- rather than the pre-feeding yard (P 0.05). Overall, providing access to straw in racks led to a reduction in pen-directed exploratory behaviour, and this may reflect the fact that sows were provided with an outlet for exploratory and/or foraging behaviour. However, the fact that sham chewing behaviour was not affected suggests that welfare benefits associated with the straw rack treatment were limited. (C) 2007 Elsevier B.V. All rights reserved.
Resumo:
This study assessed the effect of increasing fibre levels in the concentrate ration on the welfare of sows housed in a large dynamic group. One hundred and twelve Large White x Landrace sows were allocated to one of two treatments over six replicates. Treatments were as follows: (i) High Fibre diet (similar to 15% CF [Crude Fibre]), and (ii) Control diet (similar to 5% CF). Treatments were applied to two separate dynamic groups each containing 33 (+/- 3) sows in a cross-over design, after three replicates the treatments were switched between the groups. Approximately nine sows were replaced in each of these groups at 3-week intervals (each replacement constituting a replicate of the study). Sows on the high fibre diet spent a greater percentage of time lying (High Fibre: 43.8, Control. 28.0, SEM 3.25%), while sows on the control diet spent more time sham chewing (High Fibre: 7.2, Control: 28.8, SEM 1.55%). Sows newly introduced to the group on the high fibre treatment spent proportionally more time in the kennel areas compared to newly introduced sows in the control treatment (High Fibre. 0.893, Control. 0 788, SEM 5 10) In general, aggression occurred at a very low frequency and overall levels did not differ between treatments (High Fibre: 0.005, Control: 0.003, SEM 0.0007 [occurrences per min)). However, sows in the control treatment performed head thrusting (High Fibre: 0.02, Control: 0.00, SEM 0.001 [occurrences per mini), and biting behaviour (High Fibre. 002, Control. 0.01, SEM 0.002 [occurrences per min]) more frequently than sows on the high fibre diet. There was no effect of treatment on physiological parameters such as plasma cortisol (High Fibre: 1.34, Control: 1.44, SEM 0.114 ng ml(-1)) or haptoglobin levels (High Fibre. 0.73, Control. 0.64, SEM 0.080 mg ml(-1)). In summary, provision of a high fibre diet had a positive effect on the welfare of group-housed dry sows Sows on the high fibre treatment spent more time resting in the kennel areas, less time performing stereotypic behaviours and showed a reduction in some aggressive behaviours relative to sows fed the control diet.
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Forty-eight Large White x Landrace multiparous sows were mixed into twelve groups of four animals after their piglets were weaned. These groups were defined as static, with no animals being added to or removed from the groups after their formation. Aggressive and submissive behaviours were recorded continuously for 9 h after the sows were mixed, and the sows were assigned high or low social status on the basis of their relative aggressiveness and success in aggressive interactions. After five weeks, each static group was mixed into a dynamic group of 40+/-2 sows for an 11-week period. Three static groups (ie 12 animals) at a time were added to the dynamic group at three-week intervals; the same number of animals was removed at these time-points in order to maintain the group number at 40+/-2. Injury levels increased significantly with the transition from static groups to the dynamic group (P