Near-field scanning optical microscopy of molecular aggregates: The role of light polarization.

We consider theoretically near-field absorption spectra of molecular aggregates stemming from a scattering scanning near-field optical microscopy type setup. Our focus is on the dependence on the direction and polarization of the incoming electromagnetic radiation, which induces a Hertz dipole with a specific orientation at the tip-apex. Within a simple description, which is based on the eigenstates of the aggregate, absorption spectra are calculated for the near field created by this dipole. We find that the spatial patterns of the spectra have a strong dependence on the orientation of this tip-dipole, which can be understood by considering three basic functions that only depend on the arrangement of the aggregate and the molecule tip distance, but not on the orientation of the tip-dipole. This allows direct access to spatial dependence of the aggregate eigenstates. For the important cases of one- and two-dimensional systems with parallel molecules, we discuss these spectra in detail. The simple numerically efficient approach is validated by a more detailed description where the incoming radiation and the interaction between the tip and molecules are explicitly taken into account.

Fibrodysplasia Ossificans Progressiva in a Four year Old Child.

INTRODUCTION: Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disoder characterized by bone formation within muscles tendons and ligaments. It has an incidence of one in two million. We hereby report a case of FOP in a four year male child from a tribal family in orissa. CASE REPORT: 4 yr old male child presented with gradual development of stiffness of neck and hard nodules on his body for which his parents had sought all sort of indegenous treatment and manipulations by traditional bone setters. Patient returned to our hospital at the age of four years with widespread ossification and stiffness of neck, shoulders and back. He also had upper tibial osteochondromas and scalp nodules and valgus deformity of bilateral great toes. A diagnosis of FOP was made on clinical and radiological examination. CONCLUSION: Though rare, diagnosis of Myositis ossificans progressiva should be considered in a child with heterotopic bone formation and valgus deformities of great toes. Being a rare condition, treatment guidelines are not clear and this condition need further research.