A survey of the incidence of copper deficiency in dairy cattle in coastal Queensland south of Brisbane

Copper deficiency in dairy cattle has been diagnosed over most of the lower watersheds of Queensland rivers south of Brisbane by analysis of livers from slaughtered animals. Blood copper concentrations were also used as an index for a few properties from which livers were not available. Samples were obtained from 127 properties, of which 95 were copper deficient. There is a correlation between the distribution of alluvial soils in this area and the incidence of copper deficiency in cattle. It is postulated that the low fertility of these alluvial soils and the dominance of narrow-leaved carpet grass (Axonopus affinis) may account for this correlation

Optimised design of fibre-based pulse compressor for gain-switched DFB laser pulses at 1.5 µm

An optical-fibre based pulse compressor for gain-switched DFB laser pulses has been optimised using a systematic procedure based on the initial complete characterisation of the laser pulses, followed by numerical simulations of the pulse propagation in different types of fibre to determine the required lengths for optimum compression. Using both linear and nonlinear compression techniques, an optimum compression factor of 12 is achieved

A geometric construction of the exceptional Lie algebras F4 and E8

We present a geometric construction of the exceptional Lie algebras F4 and E8 starting from the round 8- and 15-spheres, respectively, inspired by the construction of the Killing superalgebra of a supersymmetric supergravity background. (There is no supergravity in the paper.)Comment: 12 page

Euclidean D-branes and higher-dimensional gauge theory

We consider euclidean D-branes wrapping around manifolds of exceptional holonomy in dimensions seven and eight. The resulting theory on the D-brane---that is, the dimensional reduction of 10-dimensional supersymmetric Yang-Mills theory---is a cohomological field theory which describes the topology of the moduli space of instantons. The 7-dimensional theory is an N_T = 2 (or balanced) cohomological theory given by an action potential of Chern-Simons type. As a by-product of this method, we construct a related cohomological field theory which describes the monopole moduli space on a 7-manifold of G_2 holonomy.Comment: 23 pages (some changes in section 4.5 -- equations 27 and 28 change slightly) (missing bibliography added!

Self-similar propagation of parabolic pulses in normal-dispersion fiber amplifiers

Pulse propagation in high-gain optical fiber amplifiers with normal group-velocity dispersion has been studied by self-similarity analysis of the nonlinear Schrödinger equation with gain. For an amplifier with a constant distributed gain, an exact asymptotic solution has been found that corresponds to a linearly chirped parabolic pulse that propagates self-similarly in the amplifier, subject to simple scaling rules. The evolution of an arbitrary input pulse to an asymptotic solution is associated with the development of low-amplitude wings on the parabolic pulse whose functional form has also been found by means of self-similarity analysis. These theoretical results have been confirmed with numerical simulations. A series of guidelines for the practical design of fiber amplifiers to operate in the asymptotic parabolic pulse regime has also been developed

A holographic computation of the central charges of d=4, N=2 SCFTs

We use the AdS/CFT correspondence to compute the central charges of the d=4, N=2 superconformal field theories arising from N D3-branes at singularities in F-theory. These include the conformal theories with E_n global symmetries. We compute the central charges a and c related to the conformal anomaly, and also the central charges k associated to the global symmetry in these theories. All of these are related to the coefficients of Chern-Simons terms in the dual string theory on AdS_5. Our computation is exact for all values of N, enabling several tests of the dualities recently proposed by Argyres and Seiberg for the E_6 and E_7 theories with N=1.Comment: 16 pages; v4: one reference adde

A Q-methodology study of parental understandings of infant immunisation: Implications for health-care advice

This study used Q-methodology to explore systematically parental judgements about infant immunisation. A total of 45 parents completed a 31-statement Q-sort. Data were collected after vaccination in general practitioner practices or a private day nursery. Q factor analysis revealed four distinct viewpoints: a duty to immunise based on medical benefits, child-orientated protection based on parental belief, concern and distress and surprise at non-compliance. Additionally, there was a common view among parents that they did not regret immunising their children. Implications of these results are discussed in terms of health-care policy and future research

Supersymmetric Yang-Mills, octonionic instantons and triholomorphic curves

In four-dimensional gauge theory there exists a well-known correspondence between instantons and holomorphic curves, and a similar correspondence exists between certain octonionic instantons and triholomorphic curves. We prove that this latter correspondence stems from the dynamics of various dimensional reductions of ten-dimensional supersymmetric Yang-Mills theory. More precisely we show that the dimensional reduction of the (5+1)-dimensional supersymmetric sigma model with hyperkaehler (but otherwise arbitrary) target X to a four-dimensional hyperkaehler manifold M is a topological sigma model localising on the space of triholomorphic maps M -> X (or hyperinstantons). When X is the moduli space M_K of instantons on a four-dimensional hyperkaehler manifold K, this theory has an interpretation in terms of supersymmetric gauge theory. In this case, the topological sigma model can be understood as an adiabatic limit of the dimensional reduction of ten-dimensional supersymmetric Yang-Mills on the eight-dimensional manifold M x K of holonomy Sp(1) x Sp(1) in Spin(7), which is a cohomological theory localising on the moduli space of octonionic instantons.Comment: 26 pages, LaTeX2e (A comment and a corresponding acknowledgement added and a reference ammended