Radiation transport and internal reflection in a sphere

We construct an integral equation for the flux intensity in a scattering and absorbing medium using the integro-differential form of the radiative transfer equation in a sphere. The sphere is uniformly irradiated by an external source of arbitrary angular distribution. The Fresnel boundary conditions, which incorporate reflection and refraction, are used. For the special cases of a non-scattering medium, and in the limit of an optically transparent medium, we obtain exact solutions for specular and diffuse refection. Some numerical examples are given which give qualitative agreement with some recent work of Tian and Chiu (JQSRT, 2005).     

The propagation of sound waves and neutron waves in bounded plane geometry

Integral equations are formulated for neutron wave propagation parallel to the faces of a slab and sound wave propagation in a gas confined between parallel plates. The main physical differences arise from the different conditions satisfied by the particle distribution functions at the boundaries of the systems, i.e. neutrons can pass through a boundary unhindered whilst gas atoms are reflected from it.     

Psoriatic arthritis: Pathogenesis and novel immunomodulatory approaches to treatment

Psoriatic arthritis (PsA) is a chronic inflammatory arthropathy characterized by the association of arthritis and psoriasis. PsA runs a variable course, from mild synovitis to severe, progressive, erosive arthropathy. The pathogenesis of PsA involves alteration in the components of the immune response, although the exact cause of PsA is unknown. A number of patients with severe peripheral arthritis fail to respond to standard conventional therapy. Advances in biotechnology and in our understanding of the immunopathogenesis of PsA have led to great interest and progress in regards to biologic treatments for PsA. Notable success achieved with recently introduced biologic therapies has paved the way for further research and develpoment of additional therapies that should improve outcomes for affected patients.