Left Ventricular Morphology in Patients with Aortic Coarctation and Bicuspid Aortic Valve: Novel Insights from a Statistical Shape Modelling Framework

Background The functional implications of left ventricular (LV) morphological characterization in congenital heart disease (CHD) are not widely explored. This study qualitatively and quantitatively assessed LV shape associations with a) LV function and b) thoracic aortic morphology in patients with aortic coarctation (CoA) with/without bicuspid aortic valve (BAV). Methods A statistical shape modelling (SSM) framework was employed to analyse three-dimensional (3D) LV shapes from cardiac magnetic resonance (CMR) data in isolated CoA (n=25), CoA+BAV (n=30), isolated BAV (n=30), and age-matched healthy controls (n=25). Average 3D templates and deformations were computed. Correlations between shape data and CMR-derived morphometric parameters (i.e. sphericity, conicity) or global and apical strain values were assessed to elucidate possible functional implications. The relationship between LV shape features and arch architecture was also explored. Results The LV template was shorter and more spherical in CoA patient and LV sphericity was associated (p≤0.04) with lower global longitudinal, radial and circumferential strain, irrespective of the presence of aortic stenosis and/or regurgitation. Conversely, LV strain was not associated with arch architecture. Conclusions Differences in LV morphology were observed between CoA and BAV patients. Increasing LV sphericity was associated with reduced strain, independent of aortic arch architecture and functional aortic valve disease.

M-type (22) Kalliope: High density and differentiated interior

<p> </p> <p><strong>Introduction</strong></p> <p>Asteroid (22) Kalliope is the second largest M-type asteroid in the main-belt after (16) Psyche. Kalliope has a bright satellite (D ~ 28km), Linus, discovered in 2001 [Me01, Ma01]. Albeit being a privileged target for adaptive optics (AO) ground-based observations, its density remains elusive with values ranging between 2.4 and 3.7 g cm-<sup>3</sup> [Ma03, Dr21]. Here, we present a complete characterization of the topography, bulk density, and internal structure of Kalliope, as well as the dynamic of the system based on high angular resolution imaging observations performed with VLT/SPHERE as part of an ESO large programme (ID: 199.C-0074).</p> <p><strong>Observation</strong></p> <p>We obtained 35 images of Kalliope at 7 epochs near opposition between March and May 2018 and in June 2019 with the VLT/SPHERE/ZIMPOL AO instrument. The first apparition in 2018 covered the south pole of Kalliope while during the second it was close to an equator-on geometry. The north pole was not completely imaged, although 88% of the surface was covered at least once. We compiled 145 lightcurves from databases and we acquired new ones during the 2018 apparition to be used in the 3D shape modelling.</p> <p>For the determination of Linus’s orbit, we complemented the SPHERE images with a compilation of archival data from other large ground-based AO instruments (KeckII/NIRC2, ESO/VLT/NACO and Gemini-North/NIRI). We obtained a total of 82 measurements spanning 42 epochs from 2001 to 2019.</p> <p><strong>Methods</strong></p> <p>We generated shape models of Kalliope with three different shape modelling techniques. We first used the inversion algorithm ADAM [Vi15] and the genetic algorithm SAGE [B18, Du20] that both take lightcurves and AO images as inputs.</p> <p>We then applied our Multi-resolution PhotoClinometry by Deformation (MPCD; [C13, F20]) method on the SPHERE images to reconstruct Kalliope’s 3D shape, starting from both the ADAM and the SAGE models as initial meshes.</p> <p>To study the dynamic of the system, the relative position of Kalliope and Linus were first measured on the images. Then, we used the meta-heuristic algorithm Genoid [Va12] to accurately determine the orbital elements.</p> <p><strong>Results and conclusions</strong></p> <p>The volume of Kalliope from the different modelling techniques and the mass constrained by the precise measurements of its satellite orbit yield a density of ~4.1 g cm-<sup>3</sup>. This high density is comparable within errors to that of the metallic asteroid (16) Psyche. The best orbital solutions for the satellite are found when the quadrupole J2 tends toward 0. However, Kalliope’s shape implies a non-zero J2 when assuming a homogeneous interior density. This suggests an inhomogeneous, differentiated internal structure.</p> <p> </p> <p><strong>Bibliography</strong></p> <p>[B18] Bartczak, P. and Dudzinski, G. 2018, MNRAS, 473</p> <p>[C13] Capanna, C., Gesquière, G., Jorda, L., Lamy, P., & Vibert, D. 2013, The Visual Computer, 29, 825</p> <p>[Dr21] Drummond, J. D., Merline, W. J., Carry, B., et al. 2021, Icarus, 358</p> <p>[Du20] Dudzinski, G., Podlewska-Gaca, E., Bartczak, P., et al. 2020, MNRAS, 499</p> <p>[F20] Ferrais, M., Vernazza, P., Jorda, L., et al. 2020, A&A, 638, L15</p> <p>[Ma01] Margot, J. L. and Brown, M. E. 2001, IAU Circ., 7703, 3</p> <p>[Ma03] Margot, J. L. and Brown, M. E. 2003, Science, 300, 1939</p> <p>[Me01] Merline, W. J., Menard, F., Close, L., et al. 2001, IAU Circ., 7703, 2</p> <p>[Va12] Vachier, F., Berthier, J. and Marchis, F. 2012, A&1, 543, A68</p> <p>[Vi15] Viikinkoski, M., Kaasalainen, M., & Durech, J. 2015, A&A, 576, A8</p>

Effect of Roughness of Mussels on Cylinder Forces from a Realistic Shape Modelling

After a few weeks, underwater components of offshore structures are colonized by marine species and after few years this marine growth can be significant. It has been shown that it affects the hydrodynamic loading of cylinder components such as legs and braces for jackets, risers and mooring lines for floating units. Over a decade, the development of Floating Offshore Wind Turbines highlighted specific effects due to the smaller size of their components. The effect of the roughness of hard marine growth on cylinders with smaller diameter increased and the shape should be representative of a real pattern. This paper first describes the two realistic shapes of a mature colonization by mussels and then presents the tests of these roughnesses in a hydrodynamic tank where three conditions are analyzed: current, wave and current with wave. Results are compared to the literature with a similar roughness and other shapes. The results highlight the fact that, for these realistic roughnesses, the behavior of the rough cylinders is mainly governed by the flow and not by their motions.

Automatic modelling of human musculoskeletal ligaments – Framework overview and model quality evaluation

BACKGROUND: Accurate segmentation of connective soft tissues in medical images is very challenging, hampering the generation of geometric models for bio-mechanical computations. Alternatively, one could predict ligament insertion sites and then approximate the shapes, based on anatomical knowledge and morphological studies. OBJECTIVE: In this work, we describe an integrated framework for automatic modelling of human musculoskeletal ligaments. METHOD: We combine statistical shape modelling with geometric algorithms to automatically identify insertion sites, based on which geometric surface/volume meshes are created. As clinical use case, the framework has been applied to generate models of the forearm interosseous membrane. Ligament insertion sites in the statistical model were defined according to anatomical predictions following a published approach. RESULTS: For evaluation we compared the generated sites, as well as the ligament shapes, to data obtained from a cadaveric study, involving five forearms with 15 ligaments. Our framework permitted the creation of models approximating ligaments’ shapes with good fidelity. However, we found that the statistical model trained with the state-of-the-art prediction of the insertion sites was not always reliable. Average mean square errors as well as Hausdorff distances of the meshes could increase by an order of magnitude, as compared to employing known insertion locations of the cadaveric study. Using those, an average mean square error of 0.59 mm and an average Hausdorff distance of less than 7 mm resulted, for all ligaments. CONCLUSIONS: The presented approach for automatic generation of ligament shapes from insertion points appears to be feasible but the detection of the insertion sites with a SSM is too inaccurate, thus making a patient-specific approach necessary.

Spatial and quantitative assessment of the correlation between sinus rhythm and atrial fibrillation voltage mapping to identify low voltage substrate in persistent atrial fibrillation

Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft (DFG) through DO637/22-3 Ministerium für Wissenschaft, Forschung und Kunst Baden-Württemberg through the Research Seed Capital (RiSC) program. Introduction Presence of left atrial (LA) fibrotic low voltage substrate (LVS) is associated with high risk for arrhythmia recurrences in patients undergoing pulmonary vein isolation (PVI) for atrial fibrillation (AF). PVI and additional ablation of LVS - as identified by mapping in sinus rhythm (SR) or AF - has been reported to improve SR maintenance rates, despite differences of the extent and distribution of LA-LVS in SR versus AF. Aims To study the relationship between SR and AF voltage maps, we sought to identify the optimal AF voltage threshold providing the highest concordance in the extent and distribution of LVS when comparing voltage maps in SR vs. AF. Methods Using the statistical shape modelling software Scalismo, the voltage information from the SR and AF maps (acquired prior to PVI) from 28 patients (66 ± 7 years, 46% male, 82% persistent AF) was projected onto a representative LA-geometry. Sensitivity and specificity of LVS identification were calculated for varying thresholds during AF and the correlation between the SR (threshold 0.5mV) and AF maps was assessed and areas of agreeing LVS classification (SR & AF) were identified for each patient. The data of all 28 patients were combined to a spatial histogram of agreement between SR and AF low voltage maps. Results The correlation between SR and AF maps was high across all patients, with agreement at 60-95% of all mapped sites (Figure A: each red triangle represents one patient and the respective agreement of LVS classification and substrate extent). The optimal AF threshold - to identify LA-LVS <0.5 mV in SR - was 0.29 mV (Q1-3: 0.20-0.37 mV) and was independent of the underlying extent of LVS during SR (Figure A: each blue asterisk represents one patient and the corresponding AF threshold and substrate extent). Agreement between LVS in AF vs. SR was high across most (>90) patients on the anterior LA, lateral LA and the left atrial appendage. Lower agreement (60% of patients) was observed in the posterior wall (Figure B). Conclusions SR and AF voltage maps reveal high spatial concordance in low voltage substrate at the anterior LA, lateral LA and LA appendage, however significant discordances in LVS are found in 40% of patients at the posterior LA. Further studies on an extended patient cohort should assess if regional voltage-thresholds would result in an improved substrate concordance between AF and SR substrate maps. Abstract Figure.

Statistical shape modelling to analyse the talus in paediatric clubfoot

One fifth of idiopathic clubfoot deformities cannot be fully corrected by Serial Ponseti casting and deformity recurs in 20%–30% of cases. To avoid x-ray exposure, the joints with largely unossified bones are diagnosed with magnetic resonance images (MRI). Typically, geometric measurements are made in the MRI planes; however, this method is inaccurate compared to measurements on three-dimensional (3D) models of the joint. More accurate measurements using the 3D bone shapes may be better at identifying differences between groups; and therefore, improve diagnosis. The entire set of shape features from MRI can be analysed simultaneously through statistical shape modelling (SSM) which assesses bone morphology of clubfoot in a more sensitive way. A method for SSM of the talus is developed in this study and the shape of the normal talus is compared with the one in clubfeet with residual deformity through both geometric measurements and SSM. Significant differences between two groups were found by both methods; and therefore, might contribute to improve diagnosis of clubfoot.

ANALYSIS AND DESIGN OF G+4 RESIDENTIAL BUILDING USING ETABS

ETABS stands for Extended Three-Dimensional Analysis of Building Systems. ETABS is commonly used to analyze: Skyscrapers, concrete structures, low and high rise buildings, and portal frame structures. The case study in this paper mainly emphasizes on structural behavior of multi-storey building for different plan configurations like rectangular, C, L and I-shape. Modelling of 15-storeys R.C.C. framed building is done on the ETABS software for analysis ETABS issue, for analysis and design for building systems. ETABS features are contain powerful graphical interface coupled with unmatched modeling, analytical, and design procedures, all integrated using a common database. STAAD and ETABS both of the software are well equipped and very much capable of handling different shape of the structures, static and dynamic loadings and different material properties.