Thermodynamic behaviour of two-dimensional vesicles revisited

We study pressurised self-avoiding ring polymers in two dimensions using Monte Carlo simulations, scaling arguments and Flory-type theories, through models which generalise the model of Leibler, Singh and Fisher [Phys. Rev. Lett. Vol. 59, 1989 (1987)]. We demonstrate the existence of a thermodynamic phase transition at a non-zero scaled pressure $\tilde{p}$, where $\tilde{p} = Np/4\pi$, with the number of monomers $N \rightarrow \infty$ and the pressure $p \rightarrow 0$, keeping $\tilde{p}$ constant, in a class of such models. This transition is driven by bond energetics and can be either continuous or discontinuous. It can be interpreted as a shape transition in which the ring polymer takes the shape, above the critical pressure, of a regular N-gon whose sides scale smoothly with pressure, while staying unfaceted below this critical pressure. In the general case, we argue that the transition is replaced by a sharp crossover. The area, however, scales with $N^2$ for all positive $p$ in all such models, consistent with earlier scaling theories.Comment: 6 pages, 4 figures, EPL forma

Sickle cell disease status among school adolescents and their tribal community in South Gujarat

Objectives: to create awareness, to screen samples of school adolescents and then to reach their community through them by doing surveillance for sickle cell disease. Design: Field based cross-sectional study. Settings: St Xavier`s high school and Vanraj high school of Umarpada taluka of Surat district. Subjects: School adolescents, their parents and friends. Method: After taking permission from school authority, blood samples of 948 school adolescents were taken for DTT test and then for electrophoresis. Blood samples of motivated parents and friends of those adolescents found positive for DTT was taken in subsequent visit and results were communicated to them. Results: Blood samples of 948 school adolescents, out of 1081 were tested for DTT test. It was positive in 242 samples, giving a prevalence of 25.5% for sickle cell disease. On subjecting the positive blood samples to electrophoresis, the proportion of sickle cell trait and sickle cell disease was found to be 92% and 8% respectively. Then electrophoresis was done in 64 parents and friends, 24 (37.5%) of them were found positive of which, 14 (58%) were having sickle cell trait and 10 (42%) having sickle cell disease. Conclusion: approaching community can be possible through school adolescents for conduction of surveillance of sickle cell anemi