The magnitude of the flux of biogenic particulate organic carbon (POC) exported from the surface waters of the world ocean and remineralized at depth is critical to constraining models of the global carbon cycle, yet remains controversial. The use of upper ocean sediment traps is still one of the primary tools for determining this export flux, although trap fluxes have been shown to vary signif...

We investigate Ussing’s unidirectional fluxes and flux ratios of charged tracers motivated particularly by the insightful proposal of Hodgkin and Keynes on a relation between flux ratios and channel structure. Our study is based on analysis of quasi-one-dimensional Poisson-Nernst-Planck type models for ionic flows through membrane channels. This class of models includes the Poisson equation tha...

INTRODUCTION Retrospective studies showed that hemodiafiltration was associated with a reduced risk of mortality compared with standard hemodialysis in the patients with end-stage renal disease. Recently, a few prospective randomized clinical trials found no advantage in survival with hemodiafiltration as compared with high-flux hemodialysis and low-flux hemodialysis. The aim of this study was ...