An M Theory Solution to the Strong CP Problem and Constraints on the Axiverse

We give an explicit realization of the "String Axiverse" discussed in Arvanitaki et. al \cite{Arvanitaki:2009fg} by extending our previous results on moduli stabilization in $M$ theory to include axions. We extend the analysis of \cite{Arvanitaki:2009fg} to allow for high scale inflation that leads to a moduli dominated pre-BBN Universe. We demonstrate that an axion which solves the strong-CP problem naturally arises and that both the axion decay constants and GUT scale can consistently be around $2\times 10^{16}$ GeV with a much smaller fine tuning than is usually expected. Constraints on the Axiverse from cosmological observations, namely isocurvature perturbations and tensor modes are described. Extending work of Fox et. al \cite{Fox:2004kb}, we note that {\it the observation of tensor modes at Planck will falsify the Axiverse completely.} Finally we note that Axiverse models whose lightest axion has mass of order $10^{-15}$ eV and with decay constants of order $5\times 10^{14}$ GeV require no (anthropic) fine-tuning, though standard unification at $10^{16}$ GeV is difficult to accommodate.Comment: 16 pages, 8 figures, v2 References adde

Non-Abelian discrete gauge symmetries in 4d string models

We study the realization of non-Abelian discrete gauge symmetries in 4d field theory and string theory compactifications. The underlying structure generalizes the Abelian case, and follows from the interplay between gaugings of non-Abelian isometries of the scalar manifold and field identifications making axion-like fields periodic. We present several classes of string constructions realizing non-Abelian discrete gauge symmetries. In particular, compactifications with torsion homology classes, where non-Abelianity arises microscopically from the Hanany-Witten effect, or compactifications with non-Abelian discrete isometry groups, like twisted tori. We finally focus on the more interesting case of magnetized branes in toroidal compactifications and quotients thereof (and their heterotic and intersecting duals), in which the non-Abelian discrete gauge symmetries imply powerful selection rules for Yukawa couplings of charged matter fields. In particular, in MSSM-like models they correspond to discrete flavour symmetries constraining the quark and lepton mass matrices, as we show in specific examples.Comment: 58 pages; minor typos corrected and references adde

Consumption patterns of sweet drinks in a population of Australian children and adolescents (2003–2008)

<p>Abstract</p> <p>Background</p> <p>Intake of sweet drinks has previously been associated with the development of overweight and obesity among children and adolescents. The present study aimed to assess the consumption pattern of sweet drinks in a population of children and adolescents in Victoria, Australia.</p> <p>Methods</p> <p>Data on 1,604 children and adolescents (4–18 years) from the comparison groups of two quasi-experimental intervention studies from Victoria, Australia were analysed<it>.</it> Sweet drink consumption (soft drink and fruit juice/cordial) was assessed as one day’s intake and typical intake over the last week or month at two time points between 2003 and 2008 (mean time between measurement: 2.2 years).</p> <p>Results</p> <p>Assessed using dietary recalls, more than 70% of the children and adolescents consumed sweet drinks, with no difference between age groups (p = 0.28). The median intake among consumers was 500 ml and almost a third consumed more than 750 ml per day. More children and adolescents consumed fruit juice/cordial (69%) than soft drink (33%) (p < 0.0001) and in larger volumes (median intake fruit juice/cordial: 500 ml and soft drink: 375 ml). Secular changes in sweet drink consumption were observed with a lower proportion of children and adolescents consuming sweet drinks at time 2 compared to time 1 (significant for age group 8 to <10 years, p = 0.001).</p> <p>Conclusion</p> <p>The proportion of Australian children and adolescents from the state of Victoria consuming sweet drinks has been stable or decreasing, although a high proportion of this sample consumed sweet drinks, especially fruit juice/cordial at both time points.</p

Associations of body mass index and waist circumference with: energy intake and percentage energy from macronutrients, in a cohort of australian children

Background: It is evident from previous research that the role of dietary composition in relation to the development of childhood obesity remains inconclusive. Several studies investigating the relationship between body mass index (BMI), waist circumference (WC) and/or skin fold measurements with energy intake have suggested that the macronutrient composition of the diet (protein, carbohydrate, fat) may play an important contributing role to obesity in childhood as it does in adults. This study investigated the possible relationship between BMI and WC with energy intake and percentage energy intake from macronutrients in Australian children and adolescents

Sclerosing angiomatoid nodular transformation of the spleen: CT, MR, PET, and 99mTc-sulfur colloid SPECT CT findings with gross and histopathological correlation

Sclerosing angiomatoid nodular transformation (SANT) is a benign, proliferative vascular lesion affecting the spleen. Few reports detailing the cross sectional and PET appearance of this lesion are available, and the lesion’s behavior with 99mTc-sulfur colloid scintigraphy is previously unreported. Sclerosing nodular transformation of the spleen shows increased tracer accumulation on positron emission tomography, and a central scar-like appearance with an enhancing capsule and radiating septae on CT and MR studies that reflects the gross and histopathological features of the lesion may be visible. An understanding of this pathological finding may allow prospective recognition of the sclerosing nodular transformation of the spleen on cross sectional imaging studies

A note on the Kutta condition in Glauert's solution of the thin aerofoil problem

Glauert's classical solution of the thin aerofoil problem (a coordinate transformation, and splitting the solution into a sum of a singular part and an assumed regular part written as a Fourier sine series) is usually presented in textbooks on aerodynamics without a great deal of attention being paid to the rôle of the Kutta condition. Sometimes the solution is merely stated, apparently satisfying the Kutta condition automatically. Quite often, however, it is misleadingly suggested that it is by the choice of a sine series that the Kutta condition is satisfied. It is shown here that if Glauert's approach is interpreted in the context of generalised functions, (1) the whole solution, i.e. both the singular part and any non-Kutta condition solution, can be written as a sine-series, and (2) it is really the coordinate transformation which compels the Kutta condition to be satisfied, as it enhances the edge singularities from integrable to non-integrable, and so sifts out solutions not normally representable by a Fourier series. Furthermore, the present method provides a very direct way to construct other, more singular solutions. A practical consequence is that (at least, in principle) in numerical solutions based on Glauert's method, more is needed for the Kutta condition than a sine series expansion

Polymer nanofilms with enhanced microporosity by interfacial polymerization

Highly permeable and selective membranes are desirable for energy-efficient gas and liquid separations. Microporous organic polymers have attracted significant attention in this respect owing to their high porosity, permeability, and molecular selectivity. However, it remains challenging to fabricate selective polymer membranes with controlled microporosity which are stable in solvents. Here we report a new approach to designing crosslinked, rigid polymer nanofilms with enhanced microporosity by manipulating the molecular structure. Ultra-thin polyarylate nanofilms with thickness down to 20 nm were formed in-situ by interfacial polymerisation. Enhanced microporosity and higher interconnectivity of intermolecular network voids, as rationalised by molecular simulations, are achieved by utilising contorted monomers for the interfacial polymerisation. Composite membranes comprising polyarylate nanofilms with enhanced microporosity fabricated in-situ on crosslinked polyimide ultrafiltration membranes show outstanding separation performance in organic solvents, with up to two orders of magnitude higher solvent permeance than membranes fabricated with nanofilms made from noncontorted planar monomers