Integrated optics for astronomical interferometry - VI. Coupling the light of the VLTI in K band

Our objective is to prove that integrated optics (IO) is not only a good concept for astronomical interferometry but also a working technique with high performance. We used the commissioning data obtained with the dedicated K-band integrated optics two-telescope beam combiner which now replaces the fiber coupler MONA in the VLTI/VINCI instrument. We characterize the behaviour of this IO device and compare its properties to other single mode beam combiner like the previously used MONA fiber coupler. The IO combiner provides a high optical throughput, a contrast of 89% with a night-to-night stability of a few percent. Even if a dispersive phase is present, we show that it does not bias the measured Fourier visibility estimate. An upper limit of 0.005 for the cross-talk between linear polarization states has been measured. We take advantage of the intrinsic contrast stability to test a new astronomical prodecure for calibrating diameters of simple stars by simultaneously fitting the instrumental contrast and the apparent stellar diameters. This method reaches an accuracy with diameter errors of the order of previous ones but without the need of an already known calibrator. These results are an important step of integrated optics and paves the road to incoming imaging interferometer projects

Solving practical issues of a portable Doppler ultrasound system for blood flow assessment during coronary graft surgery

This paper presents some practical issues regarding the development of a dedicated Doppler Ultrasound system (DUS) for the assessment of blood flow signal on coronary grafts during heart surgery. The DUS is composed of several processing units. This paper concentrates on front-end units: the transducer and a particular issue of the software interface for clinical evaluation, the noise cancellation technique (NCTech). The experimental set-up implemented to evaluate the transducer response is presented. The procedure employed to eliminate the noise components embedded in the DUS data is described. Each of these units was primarily tested in laboratory. Results show their effectiveness in achieving their specific goals. Comments on the overall system's performance are presented denoting the usefulness of such dedicated DUS during bypass assessment at heart surgery. © 2011 IEEE

Choroidal Haller’s and Sattler’s Layer Thickness Measurement Using 3-Dimensional 1060-nm Optical Coherence Tomography

Objectives: To examine the feasibility of automatically segmented choroidal vessels in three-dimensional (3D) 1060-nmOCT by testing repeatability in healthy and AMD eyes and by mapping Haller’s and Sattler’s layer thickness in healthy eyes Methods: Fifty-five eyes (from 45 healthy subjects and 10 with non-neovascular age-related macular degeneration (AMD) subjects) were imaged by 3D-1060-nmOCT over a 36ux36u field of view. Haller’s and Sattler’s layer were automatically segmented, mapped and averaged across the Early Treatment Diabetic Retinopathy Study grid. For ten AMD eyes and ten healthy eyes, imaging was repeated within the same session and on another day. Outcomes were the repeatability agreement of Haller’s and Sattler’s layer thicknesses in healthy and AMD eyes, the validation with ICGA and the statistical analysis of the effect of age and axial eye length (AL) on both healthy choroidalsublayers. Results: The coefficients of repeatability for Sattler’s and Haller’s layers were 35% and 21% in healthy eyes and 44% and 31% in AMD eyes, respectively. The mean6SD healthy central submacular field thickness for Sattler’s and Haller’s was 87656 mm and 141650 mm, respectively, with a significant relationship for AL (P,.001). Conclusions: Automated Sattler’s and Haller’s thickness segmentation generates rapid 3D measurements with a repeatability correspondingto reported manual segmentation. Sublayers in healthy eyes thinnedsignificantly with increasing AL. In the presence of the thinned Sattler’s layer in AMD, careful measurement interpretation is needed. Automatic choroidal vascular layer mapping may help to explain if pathological choroidal thinning affects medium and large choroidal vasculature in addition to choriocapillaris loss

Renewable energy integration: Opportunities and challenges

Renewable energy (RE) is staring to be used as the panacea for solving current climate change or global warming threats. Therefore, government, utilities and research communities are working together to integrate large-scale RE into the power grid. However, there are a number of potential challenges in integrating RE with the existing grid. The major potential challenges are as follows: unpredictable power generation, week grid system and impacts on power quality (PQ) and reliability. This chapter investigates the potential challenges in integrating RE as well as distributed energy resources (DERs) with the smart power grid including the possible deployment issues for a sustainable future both nationally and internationally. Initially, the prospects of RE with their possible deployment issues were investigated. Later, a prediction model was proposed that informs the typical variation in energy generation as well as effect on grid integration using regression algorithms. This chapter also investigates the potential challenges in integrating RE into the grid through experimental and simulation analyses. © Springer-Verlag London 2013

Segmentation validation in a non-neovascular AMD eye via a comparison of the segmented vasculature with indocyanine green angiography (ICGA).

<p>Early phase (A) and middle phase (B) angiography images show the ICGAresolution for choroidal vascular imaging. OCT B-scan centered on the fovea (C), and segmented areasare marked in red (D) to visualize vessel segmentation. The OCT B-scan (D) shows the segmentation lines for the retina between the ILM (green line) and the RBC complex. The choroid is located between the RBC complex and the sclera (yellow line). En face views are locatedat the inner choroid (E), the outer choroid (F) and the entire choroid (G) to demonstrate captured vessels and depth information. The bars represent 1 mm.</p

Average repeated choroidalsublayer thickness measurements for the central submacular field (CSM) and the total macular field ( µm).

<p>R1 and R2 represent imaging at the same session. R3 was performed on a different day. P values are stated for the difference between measurements by repeated measures ANOVA. Δ represents the difference. CI is the 95% confidence interval. LoA represents 95% limits of agreement. Data are expressed as the mean ± standard deviation.</p

Automated calculated mean for healthy Sattler's and Haller's layer thickness across the Early Treatment Diabetic Retinopathy Study grid ( µm).

<p>Data are expressed in µm and as the mean ± standard deviation (range).</p><p>a. Eyes were grouped based on the normal AL variation with refraction and age by myopia: AL≥24.5 mm, emmetropic: 24.5>AL≥23.4 mm or hyperopic:AL<23.4 mm)</p><p>b. univariate ANOVA (post-hoc test Tukey for hyperopic and myopic eyes)</p