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Fluctuation microscopy is a hybrid diffraction-imaging technique that detects medium range order in amorphous materials by examining spatial fluctuations in coherent scattering. These fluctuations appear as speckle in images and diffraction patterns. The volume of material contributing to the speckle is determined by the point-spread function (the resolution) of the imaging optics and the sample thickness. The spatial periodicities being probed are related to the diffraction vector. Statistical analysis of the speckle allows the random and non-random (ordered) contributions to be discriminated. The image resolution that gives the maximum speckle contrast, as determined by the normalized variance of the image intensity, is determined by the characteristic length scale of the ordering. Because medium range ordering length scales can extend out to about the tenth coordination shell, fluctuation microscopy tends to be a low image resolution technique. This review presents the kinematical scattering theory underpinning fluctuation microscopy and a description of fluctuation electron microscopy as it has been employed in the transmission electron microscope for studying amorphous materials. Recent results using soft x-rays for studying nanoscale materials are also presented. We summarize outstanding issues and point to possible future directions for fluctuation microscopy as a technique.

Intravenous thrombolysis reduces long-term disability and is cost-effective in acute ischemic stroke (AIS). [1][2][3] Unfortunately, intravenous thrombolysis is underused with rates <5%, 4 attributed in part to a lack of stroke specialists. In rural areas, use of intravenous thrombolysis is further restricted, exacerbated by the dearth of stroke experts and lack of access to endovascular revascularization therapies. 5,6 Hub-and-spoke telestroke networks can overcome these geographic barriers to acute stroke care, enhance stroke diagnosis, increase intravenous thrombolysis administration rates, and improve long-term outcomes. [7][8][9][10][11] In the past decade, telestroke networks have become widespread and represent an expanding model of stroke care, particularly in rural and small hospitals. 12However, telestroke networks are associated with significant upfront costs, and the absence of cost-effectiveness data has hindered further dissemination. Different stakeholders, including government and nongovernment insurers, hospital administrators, and health practitioners, may be interested in the costs and benefits of these establishments to better inform their decisions. A previous study showed that telestroke networks were cost-effective in the long term from a societal perspective. 13 To date, cost-effectiveness of telestroke networks from individual hospitals' perspectives has not been assessed. Such information would be valuable because, to a large extent, decisions on setting up (in the case of a hub hospital) or joining (in the case of a spoke hospital) a telestroke network are made by individual hospitals. Using data from 2 existing telestroke networks, we developed a decision model to assess the costeffectiveness of establishing a hub-and-spoke telestroke referral network from the perspectives of the hub, the spoke, and the network. Our goal was to determine whether the costs and benefits of a telestroke network support its implementation from these 3 key perspectives and to evaluate the sensitivity of these results across a range of plausible variations in model inputs. Methods Model OverviewA decision analytic model (Figure 1) was developed to compare the cost and effectiveness of treating AIS patients with and without a telestroke network from the perspectives of an entire network, a hub hospital, © 2012 American Heart Association, Inc. Background-A hub-and-spoke telestroke network is an effective way to extend quality acute stroke care to remote hospitals and to improve patient outcomes. This study assessed the cost-effectiveness of a telestroke network in the management of acute ischemic stroke from the perspectives of a network, a hub hospital, and a spoke hospital. Methods and Results-A model was developed to compare costs and effectiveness with and without a telestroke network over a 5-year time horizon. The model considered differences in rates of teleconsultations, intravenous thrombolysis, endovascular stroke therapies, and spoke-to-hub transfers. These inputs were estimated through the use of...

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