Is pterygium cancerous?


Is pterygium cancerous? Pterygium is a non-cancerous, triangular, fibrovascular membrane and one of the many ophthalmohelioses – ocular diseases where sunlight has been implicated in pathogenesis. Pterygia are acquired conjunctival…

What is Sigma convergence?


What is Sigma convergence? Sigma (σ)-convergence occurs when the dispersion of the levels of a given variable between different countries tends to decrease over time. The concept is derived from…