Centriole and Transition Zone Structures in Photoreceptor Cilia Revealed by Cryo-Electron Tomography

Primary cilia mediate sensory signaling in multiple organisms and cell types but have structures adapted for specific roles. Structural defects in them lead to devastating diseases known as ciliopathies in humans. Key to their functions are structures at their base: the basal body, the transition zone, the Y-shaped links, and the ciliary necklace. We have used cryo-electron tomography with subtomogram averaging and conventional transmission electron microscopy to elucidate the structures associated with the basal region of the connecting cilia of rod outer segments in mouse retina. The longitudinal variations in microtubule (MT) structures and the lumenal scaffold complexes connecting them have been determined, as well as membrane-associated transition zone structures: Y-shaped links connecting MT to the membrane, and ciliary beads connected to them that protrude from the cell surface and form a necklace-like structure. These results represent a clearer structural scaffold onto which molecules identified by genetics, proteomics, and superresolution fluorescence can be placed in our emerging model of photoreceptor sensory cilia

[Untitled image of Old Main and DeWitt Wallace Library]

https://digitalcommons.macalester.edu/art_photo2014fall/1002/thumbnail.jp

What Is A Specialty Clinic Really Capable Of?

The actual capability of a clinic can never be known with certainty unless clear and explicit performance goals are established. In the case of Veterans Administration Medical Centers (VAMCs), one of the much-watched performance measures, the percentage of patients seen within a set number of days of their desired dates (typically anywhere from 14 to 120 days), has been criticized because of its tendency to underestimate both the backlog of patients and how long veterans seeking care are actually waiting. This paper demonstrates, via a case study in a VAMC, three of the significant ways a system dynamics simulation model can help health practitioners determine the actual capability of their services. First, this model encourages the explicit setting of specific goals for performance measures that are critical but also well understood. Second, it can provide reliable estimates of the actual performance of these services and offer means to monitor it over time. Third, it can help practitioners identify realistic goals, and formulate strategies to achieve them via scheduling policies, such as capacity allocation, no-show rescheduling, overbooking and number of appointment slots used by type of patients, just to name a few

A Hybrid Modeling And Simulation Methodology For Formulating Overbooking Policies

System dynamics modeling and discrete-event simulation have been applied in the health care industry in system improvement initiatives. Although each has its strengths and weaknesses, few studies have demonstrated how these two approaches could be brought together to improve the quality of health delivery. In this paper, a feedback-based hybrid modeling and simulation methodology has been developed, one that uses a system dynamics model for policy making and a discrete-event model for day-to-day clinic operations. This method is applied to support the formulation of overbooking policies in an Orthopedic clinic to achieve the strategic goal of a maximum appointment delay of 30 days. First, the system dynamics model is run to identify the best overall overbooking policy, which is then fed into the discrete-even model to evaluate its impact on day-to-day operations in terms of the patients\u27 time in system. In this way, the policies developed by this hybrid modeling and simulation method address both the strategic (long-term) as well operational (short-term) goals of a clinic. Additionally, the approach also demonstrates that though overbooking is a commonly practiced to mitigate the negative effects of no-shows, it also can be an effective intervention strategy to reduce appointment delays