High speed imaging and algorithms for non invasive vibrations measurement

Comunicación presentada en EVACES 2011, 4th International Conference on Experimental Vibration Analysis for Civil Engineering Structures, Varenna (Lecco), Italy, October 3-5, 2011.

Spectral-domain optical coherence tomography study of macular structure as prognostic and determining factor for macular hole surgery outcome

Purpose: To evaluate postoperative spectral-domain optical coherence tomography findings after macular hole surgery. Methods: Retrospective, interventional, nonrandomized study. Overall, 164 eyes of 157 patients diagnosed with macular hole were operated on by vitrectomy and internal limiting membrane peeling. Preoperative and postoperative best-corrected visual acuity and spectral-domain optical coherence tomography images were obtained. Two groups were considered on the basis of the postoperative integrity of the back reflection line from the ellipsoid portion of the photoreceptor inner segment: group A (disruption of ellipsoid portion of the inner segment line, 60 eyes) and group B (restoration of ellipsoid portion of the inner segment line, 104 eyes). Results: Logarithm of the minimum angle of resolution best-corrected visual acuity improved significantly after the surgery of macular hole from a mean preoperative value of 0.79 ± 0.37 (range, 0.15–2.00) to a mean postoperative value of 0.35 ± 0.31 (range, 0.00–1.30) at the last follow-up visit (P < 0.01). Best-corrected visual acuity improved significantly in the 2 groups analyzed (all P < 0.01). A larger improvement was found in group B than in group A (P < 0.01). Conclusion: Ellipsoid portion of the inner segment line reconstruction seems to be a good prognostic factor for visual rehabilitation after macular hole surgery.

Seismically-induced landslides by a low-magnitude earthquake: The Mw 4.7 Ossa De Montiel event (central Spain)

The Ossa de Montiel (2015/02/23, Mw 4.7) earthquake struck the central part of Spain and was felt far from the epicenter (> 300 km). Even though ground shaking was slight (Imax = V, EMS-98 scale), the earthquake triggered many small rock falls, most at distances of 20–30 km from the epicenter, greater than previously recorded in S Spain (16 km) for earthquakes of similar magnitudes. The comparative analysis of available data for this event with records from other quakes of the Betic cordillera (S and SE Spain) seems to indicate a slower pattern of ground-motion attenuation in central Spain. This could explain why slope instabilities occurred at larger distances. Instability was more frequent, and occurred at larger distances, in road cuts than in natural slopes, implying that such slope types are highly susceptible to seismically induced landslides.

Long time remodeling during retinal degeneration evaluated by optical coherence tomography, immunocytochemistry and fundus autofluorescence

Purpose: To characterize the relationship between fundus autofluorescence (FAF), Optical Coherence Tomography (OCT) and immunohistochemistry (IHC) over the course of chronic retinal degeneration in the P23H rat. Methods: Homozygous albino P23H rats, Sprague–Dawley (SD) rats as controls and pigmented Long Evans (LE) rats were used. A Spectralis HRA OCT system was used for scanning laser ophthalmoscopy (SLO) imaging OCT and angiography. To determine FAF, fluorescence was excited using diode laser at 488 nm. A fast retina map OCT was performed using the optic nerve as a landmark. IHC was performed to correlate with the findings of OCT and FAF changes. Results: During the course of retinal degeneration, the FAF pattern evolved from some spotting at 2 months old to a mosaic of hyperfluorescent dots in rats 6 months and older. Retinal thicknesses progressively diminished over the course of the disease. At later stages of degeneration, OCT documented changes in the retinal layers, however, IHC better identified the cell loss and remodeling changes. Angiography revealed attenuation of the retinal vascular plexus with time. Conclusion: We provide for the first time a detailed long-term analysis of the course of retinal degeneration in P23H rats using a combination of SLO and OCT imaging, angiography, FAF and IHC. Although, the application of noninvasive methods enables longitudinal studies and will decrease the number of animals needed for a study, IHC is still an essential tool to identify retinal changes at the cellular level.

MRI Registration for Human Hip Kinematics

Measurement of joint kinematics can provide knowledge to help improve joint prosthesis design, as well as identify joint motion patterns that may lead to joint degeneration or injury. More investigation into how the hip translates in live human subjects during high amplitude motions is needed. This work presents a design of a non-invasive method using the registration between images from conventional Magnetic Resonance Imaging (MRI) and open MRI to calculate three dimensional hip joint kinematics. The method was tested on a single healthy subject in three different poses. MRI protocols for the conventional gantry, high-resolution MRI and the open gantry, lowresolution MRI were developed. The scan time for the low-resolution protocol was just under 6 minutes. High-resolution meshes and low resolution contours were derived from segmentation of the high-resolution and low-resolution images, respectively. Low-resolution contours described the poses as scanned, whereas the meshes described the bones’ geometries. The meshes and contours were registered to each other, and joint kinematics were calculated. The segmentation and registration were performed for both cortical and sub-cortical bone surfaces. A repeatability study was performed by comparing the kinematic results derived from three users’ segmentations of the sub-cortical bone surfaces from a low-resolution scan. The root mean squared error of all registrations was below 1.92mm. The maximum range between segmenters in translation magnitude was 0.95mm, and the maximum deviation from the average of all orientations was 1.27◦. This work demonstrated that this method for non-invasive measurement of hip kinematics is promising for measuring high-range-of-motion hip motions in vivo.

Stress Inversion Using LiDAR Tunnel Deformation Measurements

Far-field stresses are those present in a volume of rock prior to excavations being created. Estimates of the orientation and magnitude of far-field stresses, often used in mine design, are generally obtained by single-point measurements of stress, or large-scale, regional trends. Point measurements can be a poor representation of far-field stresses as a result of excavation-induced stresses and geological structures. For these reasons, far-field stress estimates can be associated with high levels of uncertainty. The purpose of this thesis is to investigate the practical feasibility, applications, and limitations of calibrating far-field stress estimates through tunnel deformation measurements captured using LiDAR imaging. A method that estimates the orientation and magnitude of excavation-induced principal stress changes through back-analysis of deformation measurements from LiDAR imaged tunnels was developed and tested using synthetic data. If excavation-induced stress change orientations and magnitudes can be accurately estimated, they can be used in the calibration of far-field stress input to numerical models. LiDAR point clouds have been proven to have a number of underground applications, thus it is desired to explore their use in numerical model calibration. The back-analysis method is founded on the superposition of stresses and requires a two-dimensional numerical model of the deforming tunnel. Principal stress changes of known orientation and magnitude are applied to the model to create calibration curves. Estimation can then be performed by minimizing squared differences between the measured tunnel and sets of calibration curve deformations. In addition to the back-analysis estimation method, a procedure consisting of previously existing techniques to measure tunnel deformation using LiDAR imaging was documented. Under ideal conditions, the back-analysis method estimated principal stress change orientations within ±5° and magnitudes within ±2 MPa. Results were comparable for four different tunnel profile shapes. Preliminary testing using plastic deformation, a rough tunnel profile, and profile occlusions suggests that the method can work under more realistic conditions. The results from this thesis set the groundwork for the continued development of a new, inexpensive, and efficient far-field stress estimate calibration method.

A magnitude do efeito placebo no síndrome das pernas Irrequietas

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2014

The Great Financial Plumbing: From Northern Rock to Banking Union. CEPS Paperback, 19 October 2015

The financial and economic crises have led to an enormous plumbing exercise, involving a fundamental re-design of the global and European regulatory and supervisory system. This book systematically assesses the big items on the G-20 and EU agendas and the effectiveness with which they have been implemented in the EU. Its publication coincides with the demand by European Commissioner Jonathan Hill, in the context of the Capital Markets Union, for a 'comprehensive review' of the impact and coherence of EU legislation in the area of financial services. Karel Lannoo argues in the book that much has been done by European policy-makers to make the financial system safer and to prevent banking crises of the magnitude that erupted in 2008 and 2011, but that the new framework puts an enormous burden on banks and supervisors to implement and enforce it correctly. With the huge amount of secondary or 'level-2' legislation in place, this process has spiralled out of control, and as member states always find new ways of ‘gold-plating’ EU rules, the EU always finds further reasons to achieve a 'single rulebook'. This process has to be brought to a halt, and mutual recognition, a basic single-market principle, reinforced. The new framework also brings huge advantages, which should offer benefits to all parties. Banking Union is a huge step forward, which introduces 'one-stop shopping' for banks in the eurozone, another basic single market principle, and a true single supervisor. The clarity of the new resolution framework should, if correctly applied, trigger early intervention and bring an end to forbearance, thereby enforcing market discipline in the banking sector. It should also avoid reliance on taxpayers' money to bail-out banks in trouble, which totalled 14% of EU GDP during the crisis.

Whole of Government Approach for Institutional and Policy Coherence

The comprehensive structure of cooperation at domestic level reflects on bilateral, regional and global level.

Strengthening the Migration-Development Nexus through Improved Policy and Institutional Coherence

The complexity of migration issues is clearly reflected by states diverging national migration policy interests that exists within one state. In line with the Swiss Report on International Cooperation on Migration of the Swiss Federal Council , this complexity requires close coordination and cooperation between the governmental institutions and all offices. Only through a close and coherent cooperation between all governmental actors involved in migration issues the migration-development nexus can be strength. The present paper will suggest how intergovernmental cooperation can lead to better policy coherence in migration by interlinking all actors involved.

SPECTRAL DOMAIN-OPTICAL COHERENCE TOMOGRAPHY IMAGE CONTRAST AND BACKGROUND COLOR SETTINGS INFLUENCE IDENTIFICATION OF RETINAL STRUCTURES.

PURPOSE To evaluate image contrast and color setting on assessment of retinal structures and morphology in spectral-domain optical coherence tomography. METHODS Two hundred and forty-eight Spectralis spectral-domain optical coherence tomography B-scans of 62 patients were analyzed by 4 readers. B-scans were extracted in 4 settings: W + N = white background with black image at normal contrast 9; W + H = white background with black image at maximum contrast 16; B + N = black background with white image at normal contrast 12; B + H = black background with white image at maximum contrast 16. Readers analyzed the images to identify morphologic features. Interreader correlation was calculated. Differences between Fleiss-kappa correlation coefficients were examined using bootstrap method. Any setting with significantly higher correlation coefficient was deemed superior for evaluating specific features. RESULTS Correlation coefficients differed among settings. No single setting was superior for all respective spectral-domain optical coherence tomography parameters (P = 0.3773). Some variables showed no differences among settings. Hard exudates and subretinal fluid were best seen with B + H (κ = 0.46, P = 0.0237 and κ = 0.78, P = 0.002). Microaneurysms were best seen with W + N (κ = 0.56, P = 0.025). Vitreomacular interface, enhanced transmission signal, and epiretinal membrane were best identified using all color/contrast settings together (κ = 0.44, P = 0.042, κ = 0.57, P = 0.01, and κ = 0.62, P ≤ 0.0001). CONCLUSION Contrast and background affect the evaluation of retinal structures on spectral-domain optical coherence tomography images. No single setting was superior for all features, though certain changes were best seen with specific settings.