Extensive Mapping Research Articles

LD-SLAM: A Robust and Accurate GNSS-Aided Multi-Map Method for Long-Distance Visual SLAM

Continuous, robust, and precise localization is pivotal in enabling the autonomous operation of robots and aircraft in intricate environments, particularly in the absence of GNSS (global navigation satellite system) signals. However, commonly employed approaches, such as visual odometry and inertial navigation systems, encounter hindrances in achieving effective navigation and positioning due to issues of error accumulation. Additionally, the challenge of managing extensive map creation and exploration arises when deploying these systems on unmanned aerial vehicle terminals. This study introduces an innovative system capable of conducting long-range and multi-map visual SLAM (simultaneous localization and mapping) using monocular cameras equipped with pinhole and fisheye lens models. We formulate a graph optimization model integrating GNSS data and graphical information through multi-sensor fusion navigation and positioning technology. We propose partitioning SLAM maps based on map health status to augment accuracy and resilience in large-scale map generation. We introduce a multi-map matching and fusion algorithm leveraging geographical positioning and visual data to address excessive discrete mapping, leading to resource wastage and reduced map-switching efficiency. Furthermore, a multi-map-based visual SLAM online localization algorithm is presented, adeptly managing and coordinating distinct geographical maps in different temporal and spatial domains. We employ a quadcopter to establish a testing system and generate an aerial image dataset spanning several kilometers. Our experiments exhibit the framework’s noteworthy robustness and accuracy in long-distance navigation. For instance, our GNSS-assisted multi-map SLAM achieves an average accuracy of 1.5 m within a 20 km range during unmanned aerial vehicle flights.

Tectonically assisted emplacement of oceanic intraplate volcanoes: The Bathymetrists Seamounts, central Atlantic

The origin of broad intraplate volcanic provinces has been related to deep mantle plumes or shallow lithospheric processes, e.g., underlying large fault systems. One example of an understudied intraplate volcanic province is the Bathymetrists Seamounts (BSM) in the central-eastern Atlantic, an area with dense and extended fracture zones, but the BSM has been associated with a mantle plume origin. Extensive bathymetric mapping and seafloor sampling show that most BSM-seamounts resemble flat-topped guyots capped by carbonate platforms. Vesicular, volcanoclastic samples imply that their tops formed near sea level, followed by reef formation during cessation of volcanism and crustal subsidence. Erosion determines the seamount irregularity proportional to their sizes. Strong ellipticity of some seamounts is related to multiple vents that erupted along fractures. The orientation of the volcanoes, carbonate platforms, and morphological lineaments of the BSM show particular trends that reveal information on their origin and formation mechanisms. Geomorphological analyses indicate a structural control on volcano emplacement related to underlying lithospheric faults resembling a Riedel shear pattern. The stress field corresponding to their orientations is related to a NE-SW tensional setting, fitting to the prevalent tectonic setting ~56–38 Ma years ago that coincides with the BSM formation and an increase in spreading rates. A change in movement of the African plate during this time, together with the reactivation of fracture zones of the strongly sheared equatorial Atlantic, created pathways in the lithosphere and possibly enhanced magmatism. The seamounts do not show distinct differences in erosion state, morphology, carbonate platform depth, or Mn-crust thickness, in contrast to what would be expected for an age progression within the seamount chain. Our observations, therefore, do not support a plume mantle source. While the magmatic source remains undefined, we show that tectonic pathways determined the shape of the seamounts and enabled the broad emplacement of the Bathymetrists seamount chain.

Towards Effective Bulgarian Competence Centre in High Performance Computing – Service Portfolio and Competences

Three years ago a new European initiative started: establishing a network of Centres of Competence in HPC in the European countries through the project EuroCC (2020-2022) in its second phase EuroCC2 (2023-2025). The goal is to accelerate the improvement of national and thus European capabilities in the area of HPC+ technologies, where HPC+ means High Performance Computing (HPC) and HPC application in HPDA and AI. In order to form an effective National Competence Centre in HPC+ technologies, we performed extensive competence mapping and now devise an extensive service portfolio, open to users from academia, public administration and industry. In this paper we present our analysis of the situation in Bulgaria as well as our approaches to make NCC and effective focus point for those that can benefit from use of HPC+ technology in their research or business.

Distribution of the grass snake (Natrix natrix) and dice snake (N. tessellata) in Bulgaria

We summarise the distribution of the two species of the genus Natrix occurring in Bulgaria, based on records from 147 peer-reviewed publications, grey literature, and data repositories, combined with unpublished data. This is the first extensive mapping for N. natrix; records fall in 560 cells of the 10-km MGRS/UTM grid, of which 102 cells (18.2%) were with published information we could not confirm with new data, 175 (31.2%) were with published and confirmed, and 283 (50.5%) were with new localities. For N. tessellata we increased the number of cells with records by 64% compared to the 2011 mapping, by identifying 445 cells with localities: 162 cells (36.4%) were previously published and unconfirmed, 152 (34.1%) were published and confirmed, and 131 (29.4%) were with new data. Gross climatic conditions for records with exact locations were assigned following the Köppen-Geiger classification; the distribution for both species does not seem to be highly correlated to climate as they were found in 9 of the 12 Köppen-Geiger classes present, only missing from the 3 classes that are limited to high elevations in Bulgaria and account for less than 1% of the area. The vertical distribution of the observations supports our knowledge that the species are most numerous at lower elevations (92.4% of records were <1000 m above sea level for N. natrix and 92.6% were <500 m for N. tessellata). Higher elevations and some lowlands remain relatively understudied and future sampling will likely reveal new localities for both species.

Dual-energy Computed Tomography Iodine Map for Breast Cancer: Comparison With Dynamic Contrast-enhanced Magnetic Resonance Imaging.

The characteristics of different breast cancers imaged using dual-energy computed tomography (DECT) are unknown. Furthermore, the differences between DECT and magnetic resonance imaging (MRI) in the ability to assess tumor extent have not been clarified. Therefore, this study aimed to evaluate the effectiveness of DECT iodine maps compared to contrast-enhanced MRI in patients with operable breast cancer. Clinicopathological data from 858 patients with breast cancer who underwent resection after DECT (100/140 kv) and MRI during 2012-2021 were collected. Tumoral iodine concentration (IC; max/Δ) was analyzed from iodine maps. Factors associated with the ability of iodine maps and MRI to predict tumor extent were analyzed with reference to resected specimens' pathological diagnosis. IC parameters varied according to the tumors' histological types and were correlated with the estrogen receptor, histological grade, and Ki-67 labeling index. In 86.2% of patients with invasive carcinoma with intraductal extension, images and resected specimen mapping were matched. Iodine maps were less accurate than MRI in identifying tumor borders in 9.8% and more accurate in 2.1% of patients. The discrepancies in assessing tumor borders between imaging modalities were associated with the tumor's IC parameters and mammary gland status. Differences in assessment between DECT and MRI in operable breast cancer are associated with IC parameters and background parenchymal enhancement. Therefore, evaluating tumor extent using DECT considering these characteristics appears to be a feasible approach.

Mapping energy citizenship in the south of Europe.

The adoption of new global approaches in the field of energy democratization requires inquiring into how people act to shape the energy system. This is where the concept of energy citizenship (ENCI) appears as a constellation of actors that enable and/or support citizens to became active participants in the debates and energy systems both in private and public sphere, or as a collective citizen that contributes to change (Pel et al., 2021). The aim of this paper is to explore the concept of ENCI in Southern Europe. Using a mixed approach, an extensive mapping of 43 ENCI initiatives in Spain (n = 29) and Portugal (n = 14) was conducted through desktop research, and a stakeholder consultation workshop (n = 7) was carried out through a focus group. Results revealed the major presence of collective ENCI types, with the citizen-based/hybrid one standing out (e.g., energy cooperatives). Most of them were motivated by the interest to contribute to energy transition or to produce and/or use renewable energy, and aimed at promoting energy saving, energy justice and reducing the carbon footprint. The general tendency is towards active participation (in Spain) and transformative forms (in Portugal). The possibilities for citizen control in the initiatives analysed is still limited. These results were confirmed by stakeholders who, additionally, pointed out the major political, social, economic, and geographical factors related to ENCI forms. In short, various types of ENCI could be validated in the Spanish and Portuguese context, showing a commitment to sustainability, democracy, and energy justice. Other non-evidenced forms may be raised as a challenge to further in-depth research on latent forms of ENCI in Southern Europe.

Methodology for Simultaneous Simulation of Convective And Radiative Heating

During the ascent flight of a Launch Vehicle (LV), certain regions are exposed to radiative and convective heating simultaneously. A typical example is the flexible multilayer thermal barrier for launch vehicle base region which experiences both radiative heating from the plume and hot nozzle divergent as well as convective heating due to reverse flow. To design and evaluate the effectiveness of the thermal barrier, simultaneous simulation of both radiative and convective heating is essential. This was made possible by the utilization of controlled radiant heaters and a Convective Heating System (CHS), both acting simultaneously in a pre-designated sequence. Such a simulation is very challenging since, the simultaneous simulation of radiative heating and convective heating mutually interferes with their respective independent control systems. Besides, the influence of the boundary conditions in the heat transfer process is different for radiative and convective heating. Hence, a novel technique was adopted to isolate the respective control systems. Detailed tests were undertaken to map the flow field at various distances from the exit to determine the position of the test article. After extensive mapping, the facility was utilized for simulations of both radiative and convective heating simultaneously on a thermal protection element in the launch vehicle base region, which experiences simultaneous simulation of convective and radiative heating. The studies were able to bring out the effect of hot gas permeability and thermal response and ascertain that the back wall temperatures are within allowable temperature constraint. This mode of simulation is a new technique where both simultaneous simulation of convection and radiation was undertaken to simulate the actual environments of flight on a specific system

Simultaneously discovering the fate and biochemical effects of pharmaceuticals through untargeted metabolomics

Untargeted metabolomics is an established approach in toxicology for characterising endogenous metabolic responses to xenobiotic exposure. Detecting the xenobiotic and its biotransformation products as part of the metabolomics analysis provides an opportunity to simultaneously gain deep insights into its fate and metabolism, and to associate the internal relative dose directly with endogenous metabolic responses. This integration of untargeted exposure and response measurements into a single assay has yet to be fully demonstrated. Here we assemble a workflow to discover and analyse pharmaceutical-related measurements from routine untargeted UHPLC-MS metabolomics datasets, derived from in vivo (rat plasma and cardiac tissue, and human plasma) and in vitro (human cardiomyocytes) studies that were principally designed to investigate endogenous metabolic responses to drug exposure. Our findings clearly demonstrate how untargeted metabolomics can discover extensive biotransformation maps, temporally-changing relative systemic exposure, and direct associations of endogenous biochemical responses to the internal dose.

Developing an empirical model for assessment of total nitrogen inflow to rivers and lakes in the Biebrza river watershed, Poland

Nitrogen load is crucial for its application in various fields such as agriculture and improving water quality control for authorities responsible for establishing agricultural policies in the area. The calculation of nitrogen load using existing equations is not applicable for all types of rivers, thus requiring the development of a new equation that can be applied to lakes and rivers in the Biebrza river catchment. To determine the new equation, extensive mapping of the catchment area was conducted, which was adjusted to precipitation and runoff in the area, allowing the observed results to be compared. Based on several analyses, the new equation has better accuracy, RMSE of the new model-based estimation decreased by 65.9% in 2005–2015 and 62.2% in 2016–2021 for river and 92% in 2008–2019 and 95% in 2020–2021 for lakes. Therefore, the application of the new calibrated empirical model provides results close to the real values and it can be used in the Biebrza river basin to simulate the total nitrogen runoff.

Spatial Prediction of Soil Particle-Size Fractions Using Digital Soil Mapping in the North Eastern Region of India

Numerous applications in agriculture, climate, ecology, hydrology, and the environment are severely constrained by the lack of detailed information on soil texture. The purpose of this study was to predict soil particle-size fractions (PSF) in the Ri-Bhoi district of Meghalaya state, India, using a random forest model (RF). For the modeling of soil particle-size fractions, we employed 95 soil profiles (456 depth-wise layers) gathered from a recent national land resource inventory as well as currently accessible environmental variables. Sand, silt, and clay content were predicted using the Random Forest model at varied depths of 0–5, 5–15, 30–60, 60–100, and 100–200 cm. Our results showed the R2 for sand was found to be 0.30 (0–5 cm), 0.28 (5–15 cm), and 0.21 (15–30 cm). For the sand, silt, and clay fractions, respectively, the concordance correlation coefficient (CCC) was found to be greater in the 0–30 cm, 0–60 cm, and 0–15 cm depths. When there is a reasonably close monitoring of the coverage probability with a confidence level along the 1:1 line, prediction interval coverage probability (PICP) gives a decent indicator of what to anticipate. The most crucial variables for the prediction of sand and silt were channel network base level (CNBL) and LS-Factor, whereas Min Temperature of Coldest Month (°C) (BIO6) was discovered for clay prediction. For all three soil texture fractions, the range between the 5% lower and 95% higher prediction bounds was large, indicating that the existing spatial predictions may be improved. The maps of soil texture were significantly more precise, and they accurately depicted the spatial variations of particle-size fractions. Additionally, there is still a need to investigate novel methodologies for extensive digital soil mapping, which will be very advantageous for many international initiatives.

Letter: Two Practices to Improve Informed Consent for Intraoperative Brain Research.

To the Editor: We read with great enthusiasm the paper by Peabody et al1 discussing the challenges of the informed consent for clinical research in the context of intraoperative brain research. This is a crucial ethical challenge requiring deep reflexion in the current environment within the neurosurgical practice. The authors highlight the heterogeneous impact and retention of the information provided during the consent process as well the unique place occupied by the relational dimension between the surgeon and the patient during this process. They suggest the involvement of a patient's advocate and reconsent during awake craniotomy (if applied) to overcome some of the abovementioned limitations. At our center, we have established a dedicated neuro-oncology preoperative assessment clinic for discussing the diagnosis and the treatment plan with both patients and their relatives.2 We strongly agree that patient's relatives should be involved in the decision-making process from very early stages to support the patient to take the best informed decisions for himself. The introduction to potential research programs is performed by the responsible neurosurgeon although the research consent process is independent and performed by the research team. Nevertheless, the responsible neurosurgeon is at the center of the consent process given the personalized relational dimension outlined by Peabody et al1 and unique relationship between the surgeon and the patient, particularly in the setting of the awake craniotomy. A point that is worthwhile mentioning is how the research-derived information can help the clinical consent process. At our institution, we performed extensive preoperative mapping that is explained to the patients as part of their consent process.3,4 This significantly improves their understanding about the procedure, particularly the benefits and risks involved.5 Therefore, there is an active interaction between the clinical and research consent processes. Although they are independent in their nature, the information provided by one can facilitate the understanding of the other and promote a more informed decision and potential involvement in both treatment and research processes. Patient information for patients with cancer is a vital part to personalized informed consent6 and forms a national measure to hold UK oncology centers accountable. According to the National Cancer Patient Experience Survey in the United Kingdom,7 89.4% of patients, who underwent surgery for cancer, said that before their treatment started, they had the information they needed in a way they could understand. It demonstrated that although the experience was good, we still had more room for improvement and innovation in the way we educate patients and make them understand regarding their disease process. Different strategies have been used to improve the consent form process, such as personalized 2-dimensional and 3-dimensional imaging available during consent process8 which is aligned with the General Medical Council in UK recommendations in their principles of decision making and consent.9 Thus, pushing the boundaries with innovative technology that is patient friendly promoting positive patient experience would act as an important process in the armamentarium for the current and future neurosurgeons. The increase utilization10 and recent advances in intraoperative neuromonitoring and mapping paved the way to a better understanding of the mechanisms underlying the brain function. Despite being independent processes, clinical treatment and research have a dynamic interaction where the neurosurgical team has a pivotal role in integrating the information provided. We could not agree more that the patient is at the center of all the decisions made even at the time of surgery during awake procedures.1 The challenge to the surgical teams is to provide constantly updated information to allow the best decision-making process to the patients and their advocates before surgery and to the patient himself during the awake procedure.

Patterns of valley incision beneath the Greenland Ice Sheet revealed using automated mapping and classification

The Greenland Ice Sheet covers an area of 1.7 million km2, equivalent to ∼79 % of the surface of Kalaallit Nunaat (Greenland) and ∼1.2 % of the Earth's land surface. The macro-scale geomorphology beneath the ice can provide a valuable record of past ice sheet behaviour, particularly during warm periods that may serve as analogues for present and future climates. However, despite extensive mapping of the landscape by airborne radar surveying, Greenland's subglacial geomorphology remains comparatively understudied. Here we construct an automated workflow to identify, extract, and quantify the morphology of valley cross-sectional profiles across Greenland, as observed in NASA Operation IceBridge radar data. We identify 5335 cross-sectional profiles and apply a supervised machine learning method to classify valleys based on their morphological similarity to those formed by glacial or fluvial incision elsewhere in the Northern Hemisphere. Approximately two thirds of the valleys are classified as ‘glacial’, some of which reflect active incision at the modern ice sheet margin, whereas others are situated beneath cold-based, slow-moving ice, indicating that they were incised under a different ice configuration earlier in Greenland's glacial history. The presence of ‘fluvial’ valleys in the low-lying interior of northern Greenland and in mountainous southern Greenland suggests parts of the inherited landscape formed under ice-free conditions during pre- or inter-glacial times have been preserved due to negligible long-term subglacial erosion rates. Some low-lying catchments show hallmarks of a combination of fluvial, glacial, and glacio-fluvial incision, hinting at complex interplays between valley-forming processes over the history of the Greenland Ice Sheet.

The influence of taphonomy and time on the paleobotanical record of the Permian–Triassic transition of the Karoo basin (and elsewhere)

Terrestrial fossil assemblages preserved in the upper Permian–Lower Triassic strata of the Karoo Basin, South Africa, have played a central role in the interpretation of ecosystem patterns and end-Permian extinction models. However, these models need to be carefully reconsidered because of the limitations of the rock record. Four lessons learned from a multidisciplinary approach to the rocks, lithology, stratigraphy, and dating are relevant to other paleofloras in large continental basins. In reality, the Karoo paleofloral record is very sparse. Hence, reports of a near continuous fossil record in this basin should be considered as the near continuous record of erosion and time lost with sporadic plant-fossil assemblages.A review of the debate over the rate and timing of the Permian–Triassic in the Karoo Basin reinforces the need for extensive stratigraphic mapping, the analysis of depositional environments of the plants, as well as the application of a variety of dating methods. First, Late Permian to Early Triassic paleobotanical assemblages are extremely rare in the basin with only a handful of sites in the Free State and Eastern Cape Provinces. These fossil data originate from >3750 m of total measured section wherein megafloral remains are preserved in <1% of the available rock record (0.9% all megafloral elements; permineralized wood = 0.1%, adpressions = 0.8%), with spore-and-pollen assemblages only slightly more frequently encountered at 1.3%. This low occurrence is comparable with other basins. Thus, any continental fossil assemblage represents a very short temporal window into the paleobiosphere because of taphonomic effects of the soils, pedogenesis, and controls on depositional environments. Second, geochronometric and rock magnetic data, developed in a sequence stratigraphic context, are critical to constrain time and biological trends in continental successions. The missing time, diastems and hiatuses, are critically important. Third, the spatial relationships of plant-fossil assemblages are not easily correlated across the basin without an extensive dataset of the paleolandscape. In general, the Late Permian Beaufort rocks represent channels, floodplains, and braided streams rather than lakes and oxbows that are conducive to the preservation of plant parts. Finally, the temporal distribution of paleobotanical assemblages is complicated by the missing time (sediments) that has resulted in the apparent scarcity of vegetation before and after the end Permian extinction. The reported uncharacteristic diversity and abundance of plants in the Carnian–Norian Molteno Formation is most likely due to an environment conducive to preserving fossil-plant assemblages combined with a record of intensive collecting. Overall, the large inland Karoo Basin, without any marine influence or extensive volcanic deposits, has favored the preservation of vertebrate assemblages.

Vision-based underwater target real-time detection for autonomous underwater vehicle subsea exploration

Autonomous underwater vehicles (AUVs) equipped with online visual inspection systems can detect underwater targets during underwater operations, which is of great significance to subsea exploration. However, the undersea scene has some instinctive challenging problems, such as poor lighting conditions, sediment burial, and marine biofouling mimicry, which makes it difficult for traditional target detection algorithms to achieve online, reliable, and accurate detection of underwater targets. To solve the above issues, this paper proposes a real-time object detection algorithm for underwater targets based on a lightweight convolutional neural network model. To improve the imaging quality of underwater images, contrast limited adaptive histogram equalization with the fused multicolor space (FCLAHE) model is designed to enhance the image quality of underwater targets. Afterwards, a spindle-shaped backbone network is designed. The inverted residual block and group convolutions are used to extract depth features to ensure the target detection accuracy on one hand and to reduce the model parameter volume on the other hand under complex scenarios. Through extensive experiments, the precision, recall, and mAP of the proposed algorithm reached 91.2%, 90.1%, and 88.3%, respectively. It is also noticeable that the proposed method has been integrated into the embedded GPU platform and deployed in the AUV system in the practical scenarios. The average computational time is 0.053s, which satisfies the requirements of real-time object detection.

Atlas of the anatomical localization of atypical chemokine receptors in healthy mice.

Atypical chemokine receptors (ACKRs) scavenge chemokines and can contribute to gradient formation by binding, internalizing, and delivering chemokines for lysosomal degradation. ACKRs do not couple to G-proteins and fail to induce typical signaling induced by chemokine receptors. ACKR3, which binds and scavenges CXCL12 and CXCL11, is known to be expressed in vascular endothelium, where it has immediate access to circulating chemokines. ACKR4, which binds and scavenges CCL19, CCL20, CCL21, CCL22, and CCL25, has also been detected in lymphatic and blood vessels of secondary lymphoid organs, where it clears chemokines to facilitate cell migration. Recently, GPR182, a novel ACKR-like scavenger receptor, has been identified and partially deorphanized. Multiple studies point towards the potential coexpression of these 3 ACKRs, which all interact with homeostatic chemokines, in defined cellular microenvironments of several organs. However, an extensive map of ACKR3, ACKR4, and GPR182 expression in mice has been missing. In order to reliably detect ACKR expression and coexpression, in the absence of specific anti-ACKR antibodies, we generated fluorescent reporter mice, ACKR3GFP/+, ACKR4GFP/+, GPR182mCherry/+, and engineered fluorescently labeled ACKR-selective chimeric chemokines for in vivo uptake. Our study on young healthy mice revealed unique and common expression patterns of ACKRs in primary and secondary lymphoid organs, small intestine, colon, liver, and kidney. Furthermore, using chimeric chemokines, we were able to detect distinct zonal expression and activity of ACKR4 and GPR182 in the liver, which suggests their cooperative relationship. This study provides a broad comparative view and a solid stepping stone for future functional explorations of ACKRs based on the microanatomical localization and distinct and cooperative roles of these powerful chemokine scavengers.

Glacial geomorphology between the Gran Campo Nevado and Estrecho de Magallanes, Chile (52–53°S, 73°W)

ABSTRACT We present the first extensive high-resolution glacial geomorphic map west of the Andean Cordillera in southernmost Chile (52.8–53.1°S, 73.0–73.9°W). The map extends over 1565 km2 and is based on high-resolution satellite images and aerial photographs. At selected locations, the remotely mapped geomorphology was corroborated by field observations. The study area is dominated by glacial erosional landforms (77%) over depositional landforms (23%), with published submarine depositional landforms having been included (e.g. moraines). Glacial drift, kettle kame topography and lateral and frontal moraines form the primary depositional landforms and sediment associations. Glacial cirques, wide U-shaped valleys, whalebacks, roches moutonnées and scoured bedrock characterize most of the mapped area. The spatial distribution of whalebacks and roches moutonnées in the study area indicates a lack of lithological control on their formation and a warm-based, dynamic ice velocity and thickness regime during Patagonian Ice Sheet cover and retreat during the last glacial cycle.

PO-04-029 TRIANGULATING THE LV SUMMIT: A NOVEL BIPOLAR RADIOFREQUENCY CATHETER ABLATION STRATEGY

Bipolar radiofrequency catheter ablation (RFCA) is an off-label strategy used to target ventricular arrhythmias (VA) from difficult substrates such as the LV summit. To achieve greater transmural RFCA lesions in challenging anatomy with a novel bipolar RFCA strategy. N/A A 51-year-old male with familial HCM and prior catheter ablation for persistent AF presented with pallor and palpitations in the setting of wide complex tachycardia of 210 BPM (Figure A). The patient was given a bolus of IV amiodarone and externally cardioverted. Amiodarone was discontinued given his history of amiodarone-induced hyperthyroidism. During the hospitalization, he had recurrences of sustained VAs that were suppressed with lidocaine. Cardiac MRI was obtained, which showed LVEF 42% and an extensive LGE in the LV (Figure B). The patient was brought to the EP lab for VT ablation. Extensive mapping in the RVOT, distal CS, and peri-aortic area was performed. The best pacemap was achieved with the 2F EPstar catheter (Baylis Medical) in the AIV. The ablation catheter was not able to be advanced into the distal branch in the coronary sinus. A total of 17 unipolar RFCA lesions were delivered from endocardial LV but the clinical VA remained easily inducible. A second ablation catheter was advanced to the posteroseptal RVOT on the opposite side of the septum for bipolar RFCA. The 2F EPstar catheter was positioned in the AIV near the region of best pacemap for tripolar effect (Figure C). A significant difference in the ablation impedance decline was noted between unipolar and bipolar ablations utilizing this novel strategy (Figure D top - unipolar, D bottom - bipolar). Following five bipolar RCFA lesions, the clinical VA was no longer inducible. The patient tolerated the procedure well with no further recurrence of VAs. Bipolar RFCA with a mapping catheter triangulating the target may help achieve deeper lesions.

Silicon wafer defect pattern detection using machine learning

A silicon integrated circuit has been created on silicon wafers by diffusing doping materials on the surface of the same. The silicon wafer is a thin disk made from semiconductor material (mostly ultrapure silicon). Silicon chip fabrication is an industrial process; hence defects occur on silicon wafers caused by unclean factory environment, production machine errors and fabrication process errors. The accurate classification of wafer defects provides information for engineers through regular patterns in the processes. Manual inspection of every chip is not economically feasible. In this study, WM-811k is used as the dataset. This is one of the most extensive wafer bin map dataset available open source on kaggle. It was created by MIRLABS. The dataset was compiled by taking the test data on 811,457 silicon wafer, in which each wafer map image was collected from real-world fabrication. A CNN and DNN model is used to classify the defect patterns.

PO-04-062 CRYOABLATION OF INTRAMURAL SUBSTRATE IN AN IDIOPATHIC CRUX VT MAPPED BY NAVIGATING OTHERWISE INACCESSIBLE CS ANATOMY USING 2FR MAPPING CATHETER

Idiopathic cardiac crux VTs are are difficult to map and ablate due to their inaccessible location often requiring epicardial ablation. We report a unique case of a recurrent idiopathic crux VT originating near a trifurcated confluence of CS branches that required extensive mapping only accessible with the 2Fr EP catheter that was successfully ablated with cryoablation (due to proximity to coronary artery) from within the CS and the site-opposite (epicardially). Case Report A 40 year old man with idiopathic VT (normal Echo and cardiac MRI without LGE), prior endocardial VT ablation (RV septum and mid MCV), asthma, OSA, and the Arnold-Chiari malformation, was noted to have continued symptomatic PVCs and monomorphic wide-complex tachycardia at 164 bpm. A monomorphic VT (Figure) with CL 320-380 ms was only inducible with isoproterenol infusion at 20mcg/kg/min. We attempted to better define the CS anatomy and assess if there is a route via the CS to reach the Crux. The main body CS was noted to have a trifurcation into the MCV, a posterolateral branch and an anterior branch (extension of the CS main body) all meeting at an area of confluence (Figure 1). Detailed mapping was made possible using the CS-L telescoping catheter to carry the smaller 2French EP Star catheter deep into the multiple CS branches. We noted that the proximal MCV was 28ms early in VT (but not the best pace match) and the proximal lateral CS branch across from the MCV early site within the confluence had the best pace match. This suggests the origin was likely deep in between the two sites with the exit closer to the lateral branch site. Given that we noted that the PDA is in borderline proximity (5-6mm) to the site of ablation on coronary angiography, we chose to use to cryoablation (8 minute lesions) at the confluence of these branches at the marked sites to mitigate coronary injury. VT terminated with ablations at this site. Epicardial mapping was performed and no scar was noted. An additional single lesion was performed at the site opposite from the confluence with the best pace-map and VT was no longer inducible on repeat testing with isoproterenol. CSL telescoping catheter harboring the EP star catheter can be used to overcome challenging CS anatomy to bracket the Crux VT origin. Cryoablation (not without risk completely) can be potentially effective for Crux VTs approached from CS, especially if within borderline proximity to a coronary artery.

PO-04-077 EPICARDIAL ABLATION OF A PREVIOUSLY FAILED RIGHT LATERAL ACCESSORY PATHWAY

Catheter ablation is a potentially curative treatment for accessory pathways. However, ablation of right lateral accessory pathways is challenging and has a lower procedural success rate and high recurrence rate due to catheter instability and difficulty in catheter manipulation, inadequate tissue contact and structural heart disease like Ebstein's anomaly. We describe a challenging case of WPW syndrome with right lateral accessory pathway, where the pathway was located epicardially. N/A N/A A 23-year-old female with history of recurrent palpitations was evaluated and diagnosed as a case of WPW syndrome with right free wall pathway with structurally normal heart and normal biventricular function and failed ablation twice in 2018 and 2020. In view of recurrent symptoms, patient was started on anti-arrhythmic therapy. As the patient was refractory to flecainide, sotalol and amiodarone , she was referred to our center for a repeat ablation. Baseline ECG showed manifest pre-excitation. A standard electrophysiology study was performed under general anaesthesia with sequential endocardial and epicardial mapping approach. Retrograde ERP (effective refractory period) of the pathway was 240 ms whereas antegrade ERP was 340 ms (on amiodarone and general anaesthesia). Orthodromic atrio-ventricular reciprocating tachycardia was easily induced by programmed stimulation with a tachycardia cycle length of 470 ms with earliest atrial electrogram noted in the lateral right atrium. However, despite extensive mapping of the tricuspid annulus, ablation at the earliest endocardial site failed to terminate the tachycardia. Hence, epicardial access was obtained using Sosa’s tenchique and mapping along the tricuspid annulus was performed. At lateral tricuspid annulus epicardially, fused atrial and ventricular signals were obtained with local ventricular signal preceding the surface delta wave by 35 ms. Right coronary angiography revealed safe distance between the right coronary artery and the site of ablation. Epicardial ablation at this site led to loss of accessory pathway conduction within 5 seconds. Post ablation, no tachycardia was inducible despite aggressive pacing protocols and bidirectional AV block was demonstrated using intravenous adenosine. At 1-year follow-up, patient is asymptomatic with no evidence of accessory pathway conduction. Epicardial mapping and ablation should be considered in previously failed cases of endocardial ablation of right lateral accessory pathways.