Long-term access to support for people with sight loss

The impact of sight loss on everyday life changes over time, through further deterioration of vision, as well as a result of other physical changes and key events in people’s lives. As such, even the support needs of people with relatively stable visual impairment are likely to change throughout their life course. This article explores the long-term support needs of people with sight loss and the barriers they face when accessing services over time and at the time of need. Data from biographical interviews with 36 participants with sight loss is presented, with particular focus upon three illustrative case studies. The study reveals that many participants experienced problems gaining information about, and access to, services in the short and longer term. There is a need for systematic referral from clinical services to social and voluntary services and for regular follow-up to identify and respond to people’s changing needs

Eogenetic Karst from the Perspective of an Equivalent Porous Medium

The porosity of young limestones experiencing meteoric diagenesis in the vicinity of their deposition (eogenetic karst) is mainly a double porosity consisting of touching-vug channels and preferred passageways lacing through a matrix of interparticle porosity. In contrast, the porosity of limestones experiencing subaerial erosion following burial diagenesis and uplift (telogenetic karst) is mainly a double porosity consisting of conduits within a network of fractures. The stark contrast between these two kinds of karst is illustrated by their position on a graph showing the hydraulic characteristics of an equivalent porous medium consisting of straight, cylindrical tubes (n-D space, where n is porosity,D is the diameter of the tubes, and logn is plotted against logD). Studies of the hydrology of small carbonate islands show that large-scale, horizontal hydraulic conductivity (K) increases by orders of magnitude during the evolution of eogenetic karst. Earlier petrologic studies have shown there is little if any change in the total porosity of the limestone during eogenetic diagenesis. The limestone of eogenetic karst, therefore, tracks horizontally inn-D space. In contrast, the path from initial sedimentary material to telogenetic karst comprises a descent on the graph with reduction ofn during burial diagenesis, then a sideways shift with increasingD due to opening of fractures during uplift and exposure, and finally an increase inD andn during development of the conduits along the fractures. Eogenetic caves are mainly limited to boundaries between geologic units and hydrologic zones: stream caves at the contact between carbonates and underlying impermeable rocks (and collapse-origin caves derived therefrom); vertical caves along platform-margin fractures; epikarst; phreatic pockets (banana holes) along the water table; and flank margin caves that form as mixing chambers at the coastal freshwater-saltwater “interface”. In contrast, the caverns of telogenetic karst are part of a system of interconnected conduits that drain an entire region. The eogenetic caves of small carbonate islands are, for the most part, not significantly involved in the drainage of the island