Computational Analysis of Mapping Catheter Geometry and Contact Quality Effects on Rotor Detection in Atrial Fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia and catheter mapping has been proved to be an effective approach for detecting AF drivers to be targeted by ablation. Among drivers, the so-called rotors have gained the most attention: their identification and spatial location could help to understand which patient-specific mechanisms are acting, and thus to guide the ablation execution. Since rotor detection by multi-electrode catheters may be influenced by several structural parameters including inter-electrode spacing, catheter coverage, and endocardium-catheter distance, in this study we proposed a tool for testing the ability of different catheter shapes to detect rotors in different conditions. An approach based on the solution of the monodomain equations coupled with a modified Courtemanche ionic atrial model, that considers an electrical remodeling, was applied to simulate spiral wave dynamics on a 2D model for 7.75 s. The developed framework allowed the acquisition of unipolar signals at 2 KHz. Two high-density multipolar catheters were simulated (Advisor™ HD Grid and PentaRay®) and placed in a 2D region in which the simulated spiral wave persists longer. The configuration of the catheters was then modified by changing the number of electrodes, inter-electrodes distance, position, and atrial-wall distance for assessing how they would affect the rotor detection. In contact with the wall and at 1 mm distance from it, all the configurations detected the rotor correctly, irrespective of geometry, coverage, and inter-electrode distance. In the HDGrid-like geometry, the increase of the inter-electrode distance from 3 to 6 mm caused rotor detection failure at 2 mm distance from the LA wall. In the PentaRay-like configuration, regardless of inter-electrode distance, rotor detection failed at 3 mm endocardium-catheter distance. The asymmetry of this catheter resulted in rotation-dependent rotor detection. To conclude, the computational framework we developed is based on realistic catheter shapes designed with parameter configurations which resemble clinical settings. Results showed it is well suited to investigate how mapping catheter geometry and location affect AF driver detection, therefore it is a reliable tool to design and test new mapping catheters.

A Parameter Refinement Method for Ptychography Based on Deep Learning Concepts

X-ray ptychography is an advanced computational microscopy technique, which is delivering exceptionally detailed quantitative imaging of biological and nanotechnology specimens, which can be used for high-precision X-ray measurements. However, coarse parametrisation in propagation distance, position errors and partial coherence frequently threaten the experimental viability. In this work, we formally introduce these actors, solving the whole reconstruction as an optimisation problem. A modern deep learning framework was used to autonomously correct the setup incoherences, thus improving the quality of a ptychography reconstruction. Automatic procedures are indeed crucial to reduce the time for a reliable analysis, which has a significant impact on all the fields that use this kind of microscopy. We implemented our algorithm in our software framework, SciComPty, releasing it as open-source. We tested our system on both synthetic datasets, as well as on real data acquired at the TwinMic beamline of the Elettra synchrotron facility.

Visual Echolocation Concept for the Colorophone Sensory Substitution Device Using Virtual Reality

Detecting characteristics of 3D scenes is considered one of the biggest challenges for visually impaired people. This ability is nonetheless crucial for orientation and navigation in the natural environment. Although there are several Electronic Travel Aids aiming at enhancing orientation and mobility for the blind, only a few of them combine passing both 2D and 3D information, including colour. Moreover, existing devices either focus on a small part of an image or allow interpretation of a mere few points in the field of view. Here, we propose a concept of visual echolocation with integrated colour sonification as an extension of Colorophone—an assistive device for visually impaired people. The concept aims at mimicking the process of echolocation and thus provides 2D, 3D and additionally colour information of the whole scene. Even though the final implementation will be realised by a 3D camera, it is first simulated, as a proof of concept, by using VIRCO—a Virtual Reality training and evaluation system for Colorophone. The first experiments showed that it is possible to sonify colour and distance of the whole scene, which opens up a possibility to implement the developed algorithm on a hardware-based stereo camera platform. An introductory user evaluation of the system has been conducted in order to assess the effectiveness of the proposed solution for perceiving distance, position and colour of the objects placed in Virtual Reality.

Kinematics of the parsec-scale jet of the blazar AO 0235+164

Radio interferometric maps of the blazar AO 0235+164 show the existence of a stationary core, and a compact jet composed of multiple receding components. In this work, we determined the structural characteristics of these jet components (core-component distance, position angle, flux density, etc.) using the statistical method for global optimization Cross-Entropy (CE). The images we analyzed were extracted from public databases, totaling 41 images at 15 GHz and 128 images at 43 GHz. Using criteria such as the value of the CE merit function, and mean residuals, we determined the optimum number of components in each map analyzed in this work. We found that jet components are distributed across all four quadrants on the plane of the sky, indicating a possible non-fixed jet orientation during the monitoring interval. The time evolution of the equatorial coordinates of the jet components were used to determine their respective speeds, ejection epochs, and mean position angles on the plane of the sky. We have identified more than 20 components in the jet of AO 0235+164, with their apparent speeds ranging roughly from 2c to 40c, and distributed across all four quadrants on the plane of the sky. From the kinematics of these jet components we could derive a lower limit of about 39 for its bulk jet Lorentz factor and an upper limit of approximately 42 degrees for its jet viewing angle.

Pollen Donor Position and Climate Factor Affecting Fruit Production of Nutmeg

<em>The quality and quantity of nutmeg fruit, seed and mace can be improved through managing fruit and seed production. Fruit development was affected by climate, flower initiation and pollination process. This study aimed to determine the correlation between climate, position, distance of pollen donor to female nutmeg trees, and the ratio of female and male trees to nutmeg yield. The study was conducted at the nutmeg germplasm collection garden at Cicurug (550 m asl), Sukabumi, tested 295 nutmeg trees from 27 locations in Indonesia. Data production of female trees was based on 2005-2017 data. All nutmeg trees were mapped using the GPS Garmin 76c5x. Tree sex was determined by male or female flowers domination in each tree. Correlation of the climate factors and production was analyzed using Pearson Correlation. The distance, position and the proportion of female to male trees were evalated by t-test at 5% level. Ratio of female and male trees to produce high yield was 4 : 1. Rainfall (280-430 mm/month) and temperature (24 - 25^oC) during the pollination period (8-7 months before harvesting) were <em>positively correlated with production by 57.9 % and 82.3 %. The position and distance of pollen donors to female trees had no effect on production. However, the distance between pollen donors and female trees above 15 m produced an average production equal to 15 m. The number of trees around tree samples had no effect on nutmeg production, but light intensity at 61,425-88,480 lux absorbed by trees could enhance the yield. Nutmeg required sunlight to penetrate plant canopy in order to induce fruit production.</em></em>

Patterns of Wave Deformational Multicontact Half-Subspace Loading

It was experimentally found that during the passage of the impact momentum through multi-indentor impact system the distortion of energy transfer in the deformation zone is influenced by such factors as the number of indentures (waveguides), their shape and distance position relative to the impact axis. Thus, the increase in the number of indentures in the impact system, on the one hand, leads to a decrease in the proportion of energy of the impact pulse per an isolated indenter, and on the other hand allows to increase the total value of energy transfer in the deformation zone compared to one-indentor scheme. The distance increase between impact axis and indentors placement regardless of their number and form, leads to a decrease in the proportion of energy transmitted to the deformation zone.

Radiographic position of mental foramen in selected urban population of Bangladesh

Purpose of this study was to investigate the most common accurate position of the mental foramen in selected Bangladeshi population which helps in several clinical procedure and nerve block anesthesia.The study sample included one hundred and one panoramic radiographs of selected urban population of Bangladesh taken in Out Patient Department, Update Dental College, Dhaka, Bangladesh. The most common Horizontal position of the mental foramen was below the root of second premolar tooth (37.6%). In vertical axis, the location of MF in lower half of body of mandible was found in all OPGs (100%).In vertical distance, Position B, which is measured by distance between 1.0 mm to 1.5 mm,is the most common position of MF in all aspect as viewed in OPGs in Bangladeshi population.In this study, the difference of the location of the mental foramen in different ethnics groups was discussed. Clinicians and anthropologists should expect to find the position of the mental foramen to be symmetrical and below the root of second premolar tooth.Update Dent. Coll. j: 2015; 5 (1): 03-09