Germ-line stem cells (GSCs) are maintained by the somatic microenvironment, or GSC niche, which ensures that GSCs can both self-renew and produce functional gametes. However, it remains unclear how the proper niche size and location are regulated within the developing gonads. In the Drosophila testis, the hub cells that form the GSC niche are derived from a subset of somatic gonadal precursors ...

The hub location problem appears in a variety of applications including airline systems, cargo delivery systems, and telecommunication network design. When we analyze the application areas separately, we observe that each area has its own characteristics. In this research we focus on cargo delivery systems. Our interviews with various cargo delivery firms operating in Turkey enabled us to deter...

Hub networks have always been acriticalissue in locating health facilities. Recently, a study has been investigated by Cocking et al. (2006)in Nouna health district in Burkina Faso, Africa, with a population of approximately 275,000 people living in 290 villages served by 23 health facilities. The travel times of the population to health services become extremely high during the rainy season, s...

Citrus supply chains (CSC) are increasingly important in research due to high loss and waste, increasing demand, wide application for other industries, differences CSCs from country country. This study proposes a new structure CSC by introducing collection points collect citrus the farms Jordan Valley transport it hub responsible receiving, packaging, transporting distribution centers. The obje...

The rapid growth of the intercity travel demand has resulted in enormous pressure on passenger transportation network a megaregion area. Optimally locating hubs and allocating demands to influence effectiveness network. This study develops hierarchical hub location model considering service availability hubs. A mixed integer linear programming formulation was developed minimize total cost opera...