The role of dimensionality and geometry in quench-induced nonequilibrium forces.

We present an analytical formalism, supported by numerical simulations, for studying forces that act on curved walls following temperature quenches of the surrounding ideal Brownian fluid. We show that, for curved surfaces, the post-quench forces initially evolve rapidly to an extremal value, whereafter they approach their steady state value algebraically in time. In contrast to the previously-studied case of flat boundaries (lines or planes), the algebraic decay for curved geometries depends on the dimension of the system. Specifically, steady-state values of the force are approached in time ast-d/2ind-dimensional spherical (curved) geometries. For systems consisting of concentric circles or spheres, the exponent does not change for the force on the outer circle or sphere. However, the force exerted on the inner circles or sphere experiences an overshoot and, as a result, does not evolve to the steady state in a simple algebraic manner. The extremal value of the force also depends on the dimension of the system, and originates from curved boundaries and the fact that particles inside a sphere or circle are locally more confined, and diffuse less freely than particles outside the circle or sphere.

Oxyntomodulin reduces expression of glucagon-like peptide 1 receptor in the brainstem of chickens.

Oxyntomodulin (OXM) is a peptide released from the gut and attenuates food intake by acting on hypothalamus. However, its role at the molecular level is not well studied. In the first section of this study, we analysed the effect of OXM on food intake behaviour after injecting into the lateral ventricle of chickens. The outcome showed that food intake decreased significantly after administering 4 nmol of OXM. In the second part, the expression of glucagon-like peptide 1 receptor (GLP-1R) in the brainstem was analysed by real-time RT-PCR. The results showed that expression of GLP-1R was reduced to 27% and 16% at 30 and 90 mins after injection of OXM respectively. In saline-injected chickens, no reduction in GLP-1R was seen. It can be concluded that OXM has a down regulatory effect on the responding receptor, GLP-1R and OXM in chicks has the same reductive effect on food intake as in the mammals.