Graph-Based Multi-Surface Segmentation of OCT Data Using Trained Hard and Soft Constraints

Optical coherence tomography (OCT) is a well-established image modality in ophthalmology and used daily in the clinic. Automatic evaluation of such datasets requires an accurate segmentation of the retinal cell layers. However, due to the naturally low signal to noise ratio and the resulting bad image quality, this task remains challenging. We propose an automatic graph-based multi-surface segmentation algorithm that internally uses soft constraints to add prior information from a learned model. This improves the accuracy of the segmentation and increase the robustness to noise. Furthermore, we show that the graph size can be greatly reduced by applying a smart segmentation scheme. This allows the segmentation to be computed in seconds instead of minutes, without deteriorating the segmentation accuracy, making it ideal for a clinical setup. An extensive evaluation on 20 OCT datasets of healthy eyes was performed and showed a mean unsigned segmentation error of 3.05 ±0.54 μm over all datasets when compared to the average observer, which is lower than the inter-observer variability. Similar performance was measured for the task of drusen segmentation, demonstrating the usefulness of using soft constraints as a tool to deal with pathologies.

Modeling of temperature and turbidity in a natural lake and a reservoir connected by pumped-storage operations

Pumped-storage (PS) systems are used to store electric energy as potential energy for release during peak demand. We investigate the impacts of a planned 1000 MW PS scheme connecting Lago Bianco with Lago di Poschiavo (Switzerland) on temperature and particle mass concentration in both basins. The upper (turbid) basin is a reservoir receiving large amounts of fine particles from the partially glaciated watershed, while the lower basin is a much clearer natural lake. Stratification, temperature and particle concentrations in the two basins were simulated with and without PS for four different hydrological conditions and 27 years of meteorological forcing using the software CE-QUAL-W2. The simulations showed that the PS operations lead to an increase in temperature in both basins during most of the year. The increase is most pronounced (up to 4°C) in the upper hypolimnion of the natural lake toward the end of summer stratification and is partially due to frictional losses in the penstocks, pumps and turbines. The remainder of the warming is from intense coupling to the atmosphere while water resides in the shallower upper reservoir. These impacts are most pronounced during warm and dry years, when the upper reservoir is strongly heated and the effects are least concealed by floods. The exchange of water between the two basins relocates particles from the upper reservoir to the lower lake, where they accumulate during summer in the upper hypolimnion (10 to 20 mg L−1) but also to some extent decrease light availability in the trophic surface layer.

Gynaecological operations: do they improve sexual life?

Aim of the study was to determine if gynaecological operations have an effect on sexual function using the current medlined literature. We performed a Medline search using the terms "sexual life/function after operative gynaecological treatment", "sexual life/function after operations for gynaecological problems", "sexual life/function after hysterectomy", "sexual life/function, incontinence" and "sexual life/function, pelvic organ prolapse". Reviews were excluded. We divided the operations into four groups of (1) combined prolapse and incontinence operations, (2) prolapse operations only, (3) incontinence operations only and (4) hysterectomy and compared pre-to postoperative sexual outcome. Thirty-six articles including 4534 patients were identified. Only 13 studies used a validated questionnaire. The other authors used self-designed and non-validated questionnaires or orally posed questions by the examiner to determine sexual function. Prolapse operations particularly posterior repair using levator plication seem to deteriorate sexual function, incontinence procedure have some worsening effect on sexual function and hysterectomy seems to improve sexual function with no differences between subtotal or total hysterectomy. Gynaecological operations do influence sexual function. However, little validated data are available to come to this conclusion.