A highly oriented cubic phase formed by lipids under shear

We demonstrate the formation of a macroscopically oriented inverse bicontinuous cubic (QII) lipid phase from a sponge (L3) phase by controlled hydration during shear flow. The L3 phase was the monoolein/ butanediol/water system; the addition of water reduces the butanediol concentration, inducing the formation of a diamond (QIID) cubic phase, which is oriented by the shear flow. The phenomenon was reproduced in both capillary and Couette geometries, indicating that this represents a robust general route for the production of highly aligned bulkQII samples, with applications in nanomaterial templating and protein research

Kinetics and mechanism of the interconversion of inverse bicontinuous cubic mesophases

This paper describes time-resolved x-ray diffraction data monitoring the transformation of one inverse bicontinuous cubic mesophase into another, in a hydrated lipid system. The first section of the paper describes a mechanism for the transformation that conserves the topology of the bilayer, based on the work of Charvolin and Sadoc, Fogden and Hyde, and Benedicto and O'Brien in this area. We show a pictorial representation of this mechanism, in terms of both the water channels and the lipid bilayer. The second section describes the experimental results obtained. The system under investigation was 2:1 lauric acid: dilauroylphosphatidylcholine at a hydration of 50% water by weight. A pressure-jump was used to induce a phase transition from the gyroid (Q(II)(G)) to the diamond (Q(II)(D)) bicontinuous cubic mesophase, which was monitored by time-resolved x-ray diffraction. The lattice parameter of both mesophases was found to decrease slightly throughout the transformation, but at the stage where the Q(II)(D) phase first appeared, the ratio of lattice parameters of the two phases was found to be approximately constant for all pressure-jump experiments. The value is consistent with a topology-preserving mechanism. However, the polydomain nature of our sample prevents us from confirming that the specific pathway is that described in the first section of the paper. Our data also reveal signals from two different intermediate structures, one of which we have identified as the inverse hexagonal (H-II) mesophase. We suggest that it plays a role in the transfer of water during the transformation. The rate of the phase transition was found to increase with both temperature and pressure-jump amplitude, and its time scale varied from the order of seconds to minutes, depending on the conditions employed

How much does teenage parenthood affect long term outcomes? A systematic review.

Background: The rates of teenage pregnancy in the UK are relatively high. Although early entry to parenthood can be a positive experience, most studies find large adverse effects on long term outcomes for the mother, child and father, in addition to being costly for the NHS. This is why the government launched its Teenage Pregnancy Strategy in 1999. However, there is growing evidence that teenage pregnancy might be mainly an indicator of disadvantage which is the underlying cause of the negative outcomes. Methods: A systematic literature review was undertaken of studies which used a UK dataset to quantify any long term outcomes of a teenage birth upon the mother, father or child. Studies were included if they used appropriate methods to isolate the causal effect of early parenthood. The databases searched included Medline, Cochrane, EconLit and Web of Science. Results: Six studies were identified by the review; five studies considered the mother’s socioeconomic outcomes, one study reported the child’s outcomes, and no studies met the inclusion criteria for the father’s outcomes. The studies suggested that early motherhood accounts for relatively few of the negative long term socioeconomic outcomes and it is predominantly an indicator of a disadvantaged family background. Conclusion: Limited evidence is available to understand the long term outcomes associated with teenage birth within the UK for the mother, father and child. Current econometric studies suggest that effective interventions to prevent teenage pregnancies will not eradicate the poorer long term socioeconomic outcomes often associated with early motherhood. Thus policy should focus on reducing initial disadvantage in addition to preventing teenage pregnancy. Additional econometric analyses around the mothers’, fathers’ and children’s long term socioeconomic and health-related outcomes would be valuable

Metachronal wave and hydrodynamic interaction for deterministic switching rowers

We employ a model system, called rowers, as a generic physical framework to define the problem of the coordinated motion of cilia (the metachronal wave) as a far from equilibrium process. Rowers are active (two-state) oscillators interacting solely through forces of hydrodynamic origin. In this work, we consider the case of fully deterministic dynamics, find analytical solutions of the equation of motion in the long wavelength (continuum) limit, and investigate numerically the short wavelength limit. We prove the existence of metachronal waves below a characteristic wavelength. Such waves are unstable and become stable only if the sign of the coupling is reversed. We also find that with normal hydrodynamic interaction the metachronal pattern has the form of stable trains of traveling wave packets sustained by the onset of anti-coordinated beating of consecutive rowers.Comment: 11 pages, 7 figure

A quest for frustration driven distortion in Y2Mo2O7

We investigated the nature of the freezing in the geometrically frustrated Heisenberg spin-glass Y2Mo2O7 by measuring the temperature dependence of the static internal magnetic field distribution above the spin-glass temperature, Tg, using the muSR technique. The evolution of the field distribution cannot be explained by changes in the spin susceptibility alone and suggests a lattice deformation. This possibility is addressed by numerical simulations of the Heisenberg Hamiltonian with magneto-elastic coupling at T>0.Comment: 5 pages 4 figures. Accepted for publication in PR

Promoting fairness in Sheffield

In the light of growing inequalities, several urban areas in the UK established Fairness Commissions between 2010 and 2013. In one of these areas, Sheffield, there was an attempt to do something different and innovative. Sheffield on average was, and remains one of the least deprived major cities in England, but also one of the most unequal. Following the publication of the Commission’s report which included an analysis of evidence and 90 recommendations, Sheffield responded by pursuing a number of city-wide initiatives involving different stakeholders. These included monitoring progress towards a fairer city, action on the living wage, a city-wide campaign to promote Sheffield as the fairest city, and ‘Sheffield Money’ to provide support for those households facing financial exclusion. The continuation of austerity measures still creates severe challenges to the ambitions and work of the Sheffield Fairness Commission, but experiences have shown how leadership through example and the co-production of an active campaign can give articulation to a shared desire to address injustices in the city

Mass along the Line of Sight to the Gravitational Lens B1608+656: Galaxy Groups and Implications for H_0

We report the discovery of four groups of galaxies along the line of sight to the B1608+656 gravitational lens system. One group is at the redshift of the primary lensing galaxy (z = 0.631) and appears to have a low mass, with eight spectroscopically confirmed members and an estimated velocity dispersion of 150 ± 60 km s^(-1). The three other groups are in the foreground of the lens. These groups contain ~10 confirmed members each and are located at redshifts of 0.265, 0.426, and 0.52. Two of the three additional groups are centered roughly on the lens system, while the third is centered ~1' south of the lens. We investigate the effect of each of the four groups on the gravitational lensing potential of the B1608+656 system, with a particular focus on the implications for the value of H_0 derived from this system. We find that each group provides an external convergence of ~0.005-0.060, depending on the assumptions made in the calculation. For the B1608+656 system, the stellar velocity dispersion of the lensing galaxy has been measured, thus breaking the mass sheet degeneracy due to the group that is physically associated with the lens. The effect of the other groups along the line of sight can be folded into the overall uncertainties due to large-scale structure (LSS) along the line of sight. Because B1608+656 appears to lie along an overdense line of sight, the LSS will cause the measurement of H_0 to be biased high for this system. This effect could be 5% or greater

Modes of Growth in Dynamic Systems

Regardless of a system's complexity or scale, its growth can be considered to be a spontaneous thermodynamic response to a local convergence of down-gradient material flows. Here it is shown how growth can be constrained to a few distinct modes that depend on the availability of material and energetic resources. These modes include a law of diminishing returns, logistic behavior and, if resources are expanding very rapidly, super-exponential growth. For a case where a system has a resolved sink as well as a source, growth and decay can be characterized in terms of a slightly modified form of the predator-prey equations commonly employed in ecology, where the perturbation formulation of these equations is equivalent to a damped simple harmonic oscillator. Thus, the framework presented here suggests a common theoretical under-pinning for emergent behaviors in the physical and life sciences. Specific examples are described for phenomena as seemingly dissimilar as the development of rain and the evolution of fish stocks.Comment: 16 pages, 6 figures, including appendi

Longitudinal SDW order in a quasi-1D Ising-like quantum antiferromagnet

From neutron diffraction measurements on a quasi-1D Ising-like Co$^{\rm 2+}$ spin compound BaCo$_{\rm 2}$V$_{\rm 2}$O$_{\rm 8}$, we observed an appearance of a novel type of incommensurate ordering in magnetic fields. This ordering is essentially different from the N{\' e}el-type ordering, which is expected for the classical system, and is caused by quantum fluctuation inherent in the quantum spin chain. A Tomonaga-Luttinger liquid (TLL) nature characteristic of the gapless quantum 1D system is responsible for the realization of the incommensurate ordering.Comment: 4pages, 4figur