Computational confirmation of scaling predictions for equilibrium polymers

We report the results of extensive Dynamic Monte Carlo simulations of systems of self-assembled Equilibrium Polymers without rings in good solvent. Confirming recent theoretical predictions, the mean-chain length is found to scale as \Lav = \Lstar (\phi/\phistar)^\alpha \propto \phi^\alpha \exp(\delta E) with exponents $\alpha_d=\delta_d=1/(1+\gamma) \approx 0.46$ and $\alpha_s = [1+(\gamma-1)/(\nu d -1)]/2 \approx 0.60, \delta_s=1/2$ in the dilute and semi-dilute limits respectively. The average size of the micelles, as measured by the end-to-end distance and the radius of gyration, follows a very similar crossover scaling to that of conventional quenched polymer chains. In the semi-dilute regime, the chain size distribution is found to be exponential, crossing over to a Schultz-Zimm type distribution in the dilute limit. The very large size of our simulations (which involve mean chain lengths up to 5000, even at high polymer densities) allows also an accurate determination of the self-avoiding walk susceptibility exponent $\gamma = 1.165 \pm 0.01$.Comment: 6 pages, 4 figures, LATE

Can curriculum design influence medical students’ attitudes to psychiatry? A comparison of two different approaches

Medical students with poor attitudes toward psychiatry are unlikely to choose it as a career, and current psychiatry recruitment is inadequate for future NHS needs. Amending medical school curricula has been suggested as one solution. We performed a unique naturalistic mixed-methods cross-sectional survey of two sequential cohorts in a UK medical school, before and after the restructuring of the entire MBChB curriculum. As well as increasing integration with other specialties, the emphasis placed on psychiatry increased throughout the course, but the final psychiatry block reduced from 8 to 6 weeks. Students experiencing the refreshed curriculum had better attitudes to psychiatry and psychiatric patients and were more positive about psychiatry as a career for themselves and others, compared to students on the old curriculum. This was demonstrated both quantitatively using validated rating scales (12/30 questions ATP-30 and 1/6 questions PEAK-6) and qualitatively using free-text responses. Restructuring undergraduate medical curricula to enhance integration may yield added value, including the potential to improve attitudes to specialties previously learned in silos, such as psychiatry. This may improve recruitment and the understanding of mental health for all future doctors

Flavor decomposition of the elastic nucleon electromagnetic form factors

The u- and d-quark contributions to the elastic nucleon electromagnetic form factors have been determined using experimental data on GEn, GMn, GpE, and GpM. Such a flavor separation of the form factors became possible up to 3.4 GeV2 with recent data on GEn from Hall A at JLab. At a negative four-momentum transfer squared Q2 above 1 GeV2, for both the u- and d-quark components, the ratio of the Pauli form factor to the Dirac form factor, F2/F1, was found to be almost constant, and for each of F2 and F1 individually, the d-quark portions of both form factors drop continuously with increasing Q2.Comment: 4 pages, 3 figure

Thermodynamics of Blue Phases In Electric Fields

We present extensive numerical studies to determine the phase diagrams of cubic and hexagonal blue phases in an electric field. We confirm the earlier prediction that hexagonal phases, both 2 and 3 dimensional, are stabilized by a field, but we significantly refine the phase boundaries, which were previously estimated by means of a semi-analytical approximation. In particular, our simulations show that the blue phase I -- blue phase II transition at fixed chirality is largely unaffected by electric field, as observed experimentally.Comment: submitted to Physical Review E, 7 pages (excluding figures), 12 figure

Osmotic Pressure of Solutions Containing Flexible Polymers Subject to an Annealed Molecular Weight Distribution

The osmotic pressure $P$ in equilibrium polymers (EP) in good solvent is investigated by means of a three dimensional off-lattice Monte Carlo simulation. Our results compare well with real space renormalisation group theory and the osmotic compressibility K \propto \phi \upd \phi/\upd P from recent light scattering study of systems of long worm-like micelles. We confirm the scaling predictions for EP based on traditional physics of quenched monodisperse polymers in the dilute and semidilute limit. Specifically, we find $P\propto \phi^{2.3}$ and, hence, $K \propto \phi^{-0.3}$ in the semidilute regime --- in agreement with both theory and experiment. At higher concentrations where the semidilute blobs become too small and hard-core interactions and packing effects become dominant, a much stronger increase % \log(P/\phi)\approx \log(\Nav^2/\phi) \propto \phi is evidenced and, consequently, the compressibility decreases much more rapidly with $\phi$ than predicted from semidilute polymer theory, but again in agreement with experiment.Comment: 7 pages, 4 figures, LATE

Warwick Medical School : A four dimensional curriculum

Medical curricula vary hugely across the world. Notions of horizontal and vertical integration and spiral curricula are present in many modern curricula although true integration happens to a varying degree. By seeing the development of a curriculum as fundamentally about integration, rather than as a process of seeking to integrate separate elements, we have developed a program that prepares students well for the complexities and rate of change of practice. The risks inherent in bringing forward the point at which learners need to deal with such substantive and fundamental complexity produces challenges. Such challenges are ones that our students have shown they can not only deal with, they are often better equipped than faculty to provide solutions for themselves, their peers and those who follow them. We present the three dimensions of integration in the Warwick Medical School curriculum and note the fourth dimension provided by our students, being student led teaching and support far beyond what is normally found in medical courses

Scaling of polymers in aligned rods

We study the behavior of self avoiding polymers in a background of vertically aligned rods that are either frozen into random positions or free to move horizontally. We find that in both cases the polymer chains are highly elongated, with vertical and horizontal size exponents that differ by a factor of 3. Though these results are different than previous predictions, our results are confirmed by detailed computer simulations.Comment: 4 pages, 4 figure

Nonequilibrium dynamics of mixtures of active and passive colloidal particles

We develop a mesoscopic field theory for the collective nonequilibrium dynamics of multicomponent mixtures of interacting active (i.e., motile) and passive (i.e., nonmotile) colloidal particles with isometric shape in two spatial dimensions. By a stability analysis of the field theory, we obtain equations for the spinodal that describes the onset of a motility-induced instability leading to cluster formation in such mixtures. The prediction for the spinodal is found to be in good agreement with particle-resolved computer simulations. Furthermore, we show that in active-passive mixtures the spinodal instability can be of two different types. One type is associated with a stationary bifurcation and occurs also in one-component active systems, whereas the other type is associated with a Hopf bifurcation and can occur only in active-passive mixtures. Remarkably, the Hopf bifurcation leads to moving clusters. This explains recent results from simulations of active-passive particle mixtures, where moving clusters and interfaces that are not seen in the corresponding one-component systems have been observed.Comment: 17 pages, 3 figure

A practical density functional for polydisperse polymers

The Flory Huggins equation of state for monodisperse polymers can be turned into a density functional by adding a square gradient term, with a coefficient fixed by appeal to RPA (random phase approximation). We present instead a model nonlocal functional in which each polymer is replaced by a deterministic, penetrable particle of known shape. This reproduces the RPA and square gradient theories in the small deviation and/or weak gradient limits, and can readily be extended to polydisperse chains. The utility of the new functional is shown for the case of a polydisperse polymer solution at coexistence in a poor solvent.Comment: 9 pages, 3 figure

Fixed-dose combination therapy (polypill) for the prevention of cardiovascular disease.

CLINICAL QUESTION: Is fixed-dose combination therapy (polypill) that combines antiplatelet, blood pressure-lowering, and cholesterol-lowering medications into a single pill associated with improved cardiovascular disease (CVD) risk factors or reduced all-cause mortality or fatal and nonfatal CVD events? Is the polypill associated with an increase in adverse events? BOTTOM LINE: Polypills are associated with greater reductions in systolic blood pressure and total cholesterol compared with usual care, placebo, or active comparators, but also with a 19% higher risk of any adverse event. Due to limited power from available evidence, the association of polypills with all-cause mortality or fatal and nonfatal CVD events is uncertain