A fluoroplanigraphy system for rapid presentation of single plane body sections

Fluoroplanigraphic system for rapid presentation of single plane body sections with reduced X ray exposure to patient

In vivo imaging of murine endocrine islets of Langerhans with extended-focus optical coherence microscopy

Aims/hypothesis: Structural and functional imaging of the islets of Langerhans and the insulin-secreting beta cells represents a significant challenge and a long-lasting objective in diabetes research. In vivo microscopy offers a valuable insight into beta cell function but has severe limitations regarding sample labelling, imaging speed and depth, and was primarily performed on isolated islets lacking native innervations and vascularisation. This article introduces extended-focus optical coherence microscopy (xfOCM) to image murine pancreatic islets in their natural environment in situ, i.e. in vivo and in a label-free condition. Methods: Ex vivo measurements on excised pancreases were performed and validated by standard immunohistochemistry to investigate the structures that can be observed with xfOCM. The influence of streptozotocin on the signature of the islets was investigated in a second step. Finally, xfOCM was applied to make measurements of the murine pancreas in situ and in vivo. Results: xfOCM circumvents the fundamental physical limit that trades lateral resolution for depth of field, and achieves fast volumetric imaging with high resolution in all three dimensions. It allows label-free visualisation of pancreatic lobules, ducts, blood vessels and individual islets of Langerhans ex vivo and in vivo, and detects streptozotocin-induced islet destruction. Conclusions/interpretation: Our results demonstrate the potential value of xfOCM in high-resolution in vivo studies to assess islet structure and function in animal models of diabetes, aiming towards its use in longitudinal studies of diabetes progression and islet transplant

The effect of Massachusetts health reform on 30 day hospital readmissions: retrospective analysis of hospital episode statistics

Objectives: To analyse changes in overall readmission rates and disparities in such rates, among patients aged 18-64 (those most likely to have been affected by reform), using all payer inpatient discharge databases (hospital episode statistics) from Massachusetts and two control states (New York and New Jersey). Design: Difference in differences analysis to identify the post-reform change, adjusted for secular changes unrelated to reform. Setting: US hospitals in Massachusetts, New York, and New Jersey. Participants: Adults aged 18-64 admitted for any cause, excluding obstetrical. Main outcome measure Readmissions at 30 days after an index admission. Results: After adjustment for known confounders, including age, sex, comorbidity, hospital ownership, teaching hospital status, and nurse to census ratio, the odds of all cause readmission in Massachusetts was slightly increased compared with control states post-reform (odds ratio 1.02, 95% confidence interval 1.01 to 1.04, P<0.05). Racial and ethnic disparities in all cause readmission rates did not change in Massachusetts compared with control states. In analyses limited to Massachusetts only, there were minimal overall differences in changes in readmission rates between counties with differing baseline uninsurance rates, but black people in counties with the highest uninsurance rates had decreased odds of readmission (0.91, 0.84 to 1.00) compared with black people in counties with lower uninsurance rates. Similarly, white people in counties with the highest uninsurance rates had decreased odds of readmission (0.96, 0.94 to 0.99) compared with white people in counties with lower uninsurance rates. Conclusions: In the United States, and in Massachusetts in particular, extending health insurance coverage alone seems insufficient to improve readmission rates. Additional efforts are needed to reduce hospital readmissions and disparities in this outcome

Fast focus field calculations

We present a fast calculation of the electromagnetic field near the focus of an objective with a high numerical aperture (NA). Instead of direct integration, the vectorial Debye diffraction integral is evaluated with the fast Fourier transform for calculating the electromagnetic field in the entire focal region. We generalize this concept with the chirp z transform for obtaining a flexible sampling grid and an additional gain in computation speed. Under the conditions for the validity of the Debye integral representation, our method yields the amplitude, phase and polarization of the focus field for an arbitrary paraxial input field on the objective. We present two case studies by calculating the focus fields of a 40×1.20 NA water immersion objective for different amplitude distributions of the input field, and a 100×1.45 NA oil immersion objective containing evanescent field contributions for both linearly and radially polarized input fields

Stationary Random Fields on the Unitary Dual of a Compact Group

We generalise the notion of wide-sense stationarity from sequences of complex-valued random variables indexed by the integers, to fields of random variables that are labelled by elements of the unitary dual of a compact group. The covariance is positive definite, and so it is the Fourier transform of a finite central measure (the spectral measure of the field) on the group. Analogues of the Cramer and Kolmogorov theorems are extended to this framework. White noise makes sense in this context and so, for some classes of group, we can construct time series and investigate their stationarity. Finally we indicate how these ideas fit into the general theory of stationary random fields on hypergroups

Intelligent Pinhole with Sub-Micrometer Resolution

An intelligent pinhole for confocal microscopy consisting of four position controlled blades forming a rectangular aperture from 3x3μm to 500 x 500 μm was built. This aperture can be positioned without drift under computer control in a positioning range with a sub-micrometer precision. Each blade is suspended by an elastic hinges and moved by a linear magnetic actuator. An integrated position transducer with a reproducibility of better than 40 nm allows a settling time of less than 75 ms. The whole pinhole system is small sized (40x40x20 mm) with an electrical consumption of less than 2W. A first application in a scanning confocal microscope demonstrated the usefulness of such a micro-opto-mechanical system