Optics of Nonuniformly Moving Media

A moving dielectric appears to light as an effective gravitational field. At low flow velocities the dielectric acts on light in the same way as a magnetic field acts on a charged matter wave. We develop in detail the geometrical optics of moving dispersionless media. We derive a Hamiltonian and a Lagrangian to describe ray propagation. We elucidate how the gravitational and the magnetic model of light propagation are related to each other. Finally, we study light propagation around a vortex flow. The vortex shows an optical Aharonov--Bohm effect at large distances from the core, and, at shorter ranges, the vortex may resemble an optical black hole.Comment: Physical Review A (submitted

SNW1 Is a Critical Regulator of Spatial BMP Activity, Neural Plate Border Formation, and Neural Crest Specification in Vertebrate Embryos

In frog and fish embryos, SNW1 is a protein required for the spatio-temporal activity of BMP signaling necessary for neural plate border formation and specification of neural crest tissue

Zebrafish as a powerful vertebrate model system for in vivo studies of cell death

Understanding and manipulating cell death pathways are critical to our ability to treat human degenerative diseases and cancer. The zebrafish Danio rerio, a common aquatic pet, has evolved as a powerful tool for the discovery of genes regulating cellular suicide both during normal vertebrate development and after genetic or environmental insult. In this review, we describe the techniques that can be applied to studying cell death in zebrafish as well as highlighting what has been discovered so far. Finally, we discuss future perspectives in the field and how they relate to human disease

Evaluation of Flow Rate, pH, Buffering Capacity, Calcium, Total Proteins and Total Antioxidant Capacity Levels of Saliva in Caries Free and Caries Active Children: An In Vivo Study

The purpose of this study was to evaluate the relationship between the physicochemical properties of saliva such as flow rate, pH, buffering capacity, calcium level, total protein and total antioxidant levels in caries free and caries active children. The present study included one hundred and twenty healthy children who were divided into two groups; group I and group II comprising of age groups 7–10 and 11–14 years, respectively. Both the groups were then sub-divided equally according to gender. They were further divided into caries free and caries active with 15 children in each group. Unstimulated saliva was collected by suction method and flow rates were determined. The samples were then analyzed for pH, buffering capacity, total protein, calcium and total antioxidant capacity. The data was statistically analyzed using student t test (unpaired). The results revealed that when all these parameters were compared among the caries free and caries active children, flow rate, pH, buffering capacity were slightly reduced in caries active children, but total protein and total antioxidant capacity of saliva increased significantly in caries active children and the total calcium decreased significantly in caries active children. Within the limitation of this study, we conclude that, the physicochemical properties of saliva play a major role in the development of caries