The social and mating system of the herbivorous reef fish Sparisoma viride:One-male versus multi-male groups

We present a detailed description of the social and mating system of the protogynous reef herbivore Sparisoma viride at the fringing reef of Bonaire (Netherlands Antilles). Initial phase (IP) fish and terminal phase (TP) males occur either in one- or in multi-male groups, which are compared quantitatively with respect to the use of space, size composition, social interactions and sexual activity. One-male groups consist of one TP male plus 1-14 IP females, whereas in multi-male groups up to 14 TP males and about twice as many LP fish share a common home range. The two social units further show marked differences in vertical distribution (one-male groups are restricted to depths between 3 and 22 m, multi-male groups mainly residing <3 m), size composition (a larger proportion of small adults live in multi-male groups), size and stability of the range (larger in one-male groups) and sexual activity (daily spawning of one-male group members inside their normal home range; no activity in multi-male groups on the shallow reef). Sexual activity occurred daily, throughout the year, with no evidence for tidal tracking or major seasonal or lunar patterns. The one-male groups constitute less than 20% of the adult stock but control up to 77% of the inhabited reef. As a result they have access to higher-yield food patches and to suitable spawning sites inside their home range. Although members of both units appear to defend their common home range against intruding conspecifics, the degree of territoriality is clearly higher in one-male groups. We discuss the relative importance of food, shelter, mates and mating sites as defended resources and some life history implications. The complex social and mating system of S. viride shows much resemblance to that of another Caribbean scarid, Scarus iserti. This complexity seems to reflect the capacity of individuals to flexibly adapt their feeding, mating and life history styles to an unpredictable environment. We propose that S. viride is a good study animal to test adaptive explanations for its territorial organization and complex life history patterns

Pyridazinediones and amino acid receptors: theoretical studies, design, synthesis, and evaluation of novel analogues

http://www.pharmacol.usyd.edu.au/thesis This thesis is primarily concerned with a class of chemical compounds known as pyridazinediones, being 6-membered aromatic rings containing two adjacent nitrogen atoms (pyridazine), doubly substituted with oxygen. In particular, the work focuses on pyridazine-3,6-diones, derivatives of maleic hydrazide (1). Understanding of the chemistry of these compounds is extended, using theoretical and synthetic techniques. This thesis is also concerned with two very important classes of receptors which bind amino acids in the brain: firstly, the inhibitory GABA receptor, which binds g-aminobutyric acid (GABA) (2) in vivo, and for which muscimol (3) is an agonist of the GABAA subclass; secondly, Excitatory Amino Acid (EAA) receptors, which bind glutamate (4) in vivo, and in particular the AMPA subclass, for which (S)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) (5) is an agonist. The connection between pyridazinediones and amino acid receptors is the design, synthesis, and evaluation of structures based on pyridazinediones as potential GABA and EAA receptor ligands. Techniques of theoretical chemistry, molecular modelling, synthetic chemistry, and in vitro pharmacology are used to explore pyridazine-3,6-dione derivatives as ligands

Determinants of Advanced Bone Age in Childhood Obesity

Background: Childhood obesity is associated with advanced bone age (BA). Previous studies suggest that androgens, oestrogens, sex hormone-binding globulin, and insulin are responsible for this phenomenon, but results are contradictory and might be biased by confounders. We aim to elucidate this matter by applying a multivariate approach. Method: We performed a correlation analysis of BA standard deviation score (SDS) with age- and sex-specific SDS for androgens, oestrogens, and with indicators of insulin secretion derived from oral glucose tolerance testing, in a group of obese children. A multivariate analysis was performed to investigate which parameters were independently predictive of BA SDS. Results: In this cohort (n = 101; mean age 10.9 years; mean BA 11.8 years; mean BMI SDS 3.3), BMI SDS was significantly correlated to BA SDS (r = 0.55, p < 0.001). In a regression analysis in the total cohort (B = 0.27, p < 0.001) as well as in females (B = 0.34, p = 0.042), males (B = 0.31, p = 0.006), and pubertal children (B = 0.32, p = 0.046), dehydroepiandrosterone sulphate (DHEAS) showed a positive, independent association with BA SD

Momentum transfer using chirped standing wave fields: Bragg scattering

We consider momentum transfer using frequency-chirped standing wave fields. Novel atom-beam splitter and mirror schemes based on Bragg scattering are presented. It is shown that a predetermined number of photon momenta can be transferred to the atoms in a single interaction zone.Comment: 4 pages, 3 figure

Conformal structures of static vacuum data

In the Cauchy problem for asymptotically flat vacuum data the solution-jets along the cylinder at space-like infinity develop in general logarithmic singularities at the critical sets at which the cylinder touches future/past null infinity. The tendency of these singularities to spread along the null generators of null infinity obstructs the development of a smooth conformal structure at null infinity. For the solution-jets arising from time reflection symmetric data to extend smoothly to the critical sets it is necessary that the Cotton tensor of the initial three-metric h satisfies a certain conformally invariant condition (*) at space-like infinity, it is sufficient that h be asymptotically static at space-like infinity. The purpose of this article is to characterize the gap between these conditions. We show that with the class of metrics which satisfy condition (*) on the Cotton tensor and a certain non-degeneracy requirement is associated a one-form $\kappa$ with conformally invariant differential $d\kappa$. We provide two criteria: If $h$ is real analytic, $\kappa$ is closed, and one of it integrals satisfies a certain equation then h is conformal to static data near space-like infinity. If h is smooth, $\kappa$ is asymptotically closed, and one of it integrals satisfies a certain equation asymptotically then h is asymptotically conformal to static data at space-like infinity.Comment: 68 pages, typos corrected, references and details adde

Multifractal analysis of the electronic states in the Fibonacci superlattice under weak electric fields

Influence of the weak electric field on the electronic structure of the Fibonacci superlattice is considered. The electric field produces a nonlinear dynamics of the energy spectrum of the aperiodic superlattice. Mechanism of the nonlinearity is explained in terms of energy levels anticrossings. The multifractal formalism is applied to investigate the effect of weak electric field on the statistical properties of electronic eigenfunctions. It is shown that the applied electric field does not remove the multifractal character of the electronic eigenfunctions, and that the singularity spectrum remains non-parabolic, however with a modified shape. Changes of the distances between energy levels of neighbouring eigenstates lead to the changes of the inverse participation ratio of the corresponding eigenfunctions in the weak electric field. It is demonstrated, that the local minima of the inverse participation ratio in the vicinity of the anticrossings correspond to discontinuity of the first derivative of the difference between marginal values of the singularity strength. Analysis of the generalized dimension as a function of the electric field shows that the electric field correlates spatial fluctuations of the neighbouring electronic eigenfunction amplitudes in the vicinity of anticrossings, and the nonlinear character of the scaling exponent confirms multifractality of the corresponding electronic eigenfunctions.Comment: 10 pages, 9 figure