Area Of Obstruction Research Articles

Efficient and low-drift point-cloud mapping method for GNSS weak and obstructed areas

Abstract Road modelling based on point-cloud data often encounters signal-rejection areas, where the absence of absolute position constraints leads to rapid error accumulation in the constructed map. To mitigate error growth, the manual setting of control points is necessary, which compromises automation in the mapping process and causes a challenging trade-off between efficiency and accuracy. To address these issues, in the present study, we designed a fast and efficient map-construction method that provides absolute pose constraints for simultaneous localisation and mapping (SLAM) based on the bidirectional filter position of global navigation satellite system (GNSS)/inertial measurement unit (IMU) integrated navigation. First, we designed an absolute position constraint factor (BF_Factor) updated at each epoch according to the reference-position difference and time-delay error, which can significantly mitigate error divergence during mobile mapping in a GNSS-rejected region. An adaptive noise model was then constructed for the above factors so that the weights of different factors could be adjusted automatically to achieve a more accurate mapping result. Finally, we conducted experimental tests on the proposed mapping approach in two scenarios that included multiple GNSS-rejected areas. Even when several hundred metres of GNSS signal-obstructed areas were present in the scene, the relocation results indicated that the three-dimensional position error obtained using point-cloud maps was <0.15 m and the pitch/roll error was better than 2°. Compared with Fastlio2 and Fastlio2-SC (Fastlio2 with Scan Context), the proposed method had a better mapping effect and higher mapping accuracy in the aforementioned scenarios. The method proposed in this paper can reduce the human cost in traditional modeling and can provide more rapid and accurate map for related industry applications. The method proposed in this paper can reduce the human cost in traditional modeling and can provide more rapid and accurate map for related industry applications.

Impact of three-dimensional imaging and printing on septal myectomy results-single centre's experience.

To assess changes in the results of septal myectomy (SM) following introduction of three-dimensional (3D) imaging and 3D printing in surgical interventions planning and performing in the single-centre settings. Between January 2007 and March 2022, 268 consecutive symptomatic patients with hypertrophic obstructive cardiomyopathy and peak pressure gradient at obstruction area ≥50 mmHg underwent conventional SM (n = 112) or SM with heart 3D modelling (n = 156). For comparative analysis, we used propensity score matching (PSM) by 14 variables and there were formed group 1PSM (conventional SM, n = 77) and group 2PSM (3D-modelled SM, n = 77). It was noted for group 2PSM: larger mean resected myocardium mass [10.0 (standard deviation 4.3) vs 5.2 (standard deviation 2.7) g], P < 0.001, no mitral valve replacement cases [0 vs 28 (36.4%), P < 0.001], no iatrogenic ventricular septal defects cases [0 vs 6 (7.8%), P = 0.028], lower rate of major complications [6 (7.8%) vs 17 (22.1%), P = 0.011], smaller residual peak systolic gradient at the obstruction level [7.0 (5.0-9.0) vs 11.0 (7.0-16.0) mmHg, P < 0.001]. During the long-term follow-up, it was noted for group 2PSM as compared to group 1PSM: lower 5-year cumulative incidence of major adverse cardiovascular events [3.8% (95% confidence interval 0.7-11.7%) vs 16.9% (9.5-26.1%), P = 0.007] and cardiac-related death [3.8% (95% confidence interval 0.7-11.7%) vs 13% (95% confidence interval 6.6-21.6%), P = 0.05]. SM based on 3D virtual and printed heart models is more effective than conventional SM.

Laparoscopic Right Hemi-hepatectomy of the Bile Duct-Obstructed Area Guided by Real-Time Fluorescence Imaging.

The regions of the liver with cholestasis caused by biliary tumors or thrombosis can be distinctly identified using indocyanine green (ICG) fluorescence imaging.1 The authors' team reported the application of bile-duct obstructed area imaging (BOAI) to assist open hepatectomy for intrahepatic cholangiocarcinoma (ICC) combined with intrahepatic bile duct obstruction previously.2 This video is the first report of real-time BOAI-guided three-dimensional (3D) laparoscopic hepatectomy using a 3D-4K fluorescence imaging system. A 65-year-old man was admitted to the authors' institution with clonorchiasis. Preoperative computed tomography (CT) and magnetic resonance cholangiopancreatography (MRCP) showed an obstruction and diffuse dilation of the right hepatic duct. A 15-min retention of ICG (ICG R15) was performed 5 days before the operation, with a 3.3% result. Preoperative planning involved performing laparoscopic right hemi-hepatectomy with regional lymph node dissection assisted by visualization technology.3 During the procedure, significant fluorescence accumulation in the right liver was shown by fluorescence imaging. With the guidance of real-time BOAI (Fig. 1), the regions of biliary obstruction were precisely resected, and the middle hepatic vein (MHV) was passively and adequately exposed on the cutting plane. Fig. 1 Administration steps for real-time bile duct-obstructed area imaging. A ICG is injected intravenously 3-5 days before operation at a dose of 0.5 mg/kg. B ICG is accumulated in the whole liver within a few minutes after injection. C ICG is selectively absorbed by the liver and excreted into the intestines, whereby it is retained in areas of biliary obstruction RESULTS: The histopathologic diagnosis indicated high-grade intraepithelial neoplasia of the right bile duct tumor without lymph node metastases and clonorchiasis. The duration of the operation was 300 min, with an intraoperative blood loss of 50 ml. No postoperative complications occurred, and the patient was discharged after 7 days. Laparoscopic right hemi-hepatectomy for the bile-duct obstructed area with the guidance of real-time BOAI is feasible and effective.

A novel protocol for three-dimensional mapping of sand tiger shark (Carcharias taurus) enclosure use in aquaria: Implications for management.

This study investigated sand tiger shark (STS; Carcharias taurus) spatial use and exclusion in public aquarium enclosures using a novel protocol for three-dimensional mapping. Fifty-one STS were observed in 14 enclosures, and swimming pattern, depth, and location were recorded in ZooMonitor. Data were converted into quantitative, three-dimensional representations using ArcGIS® Pro v. 2.9. All observed STS except one swam in circular patterns, and 80% (n = 41) showed a directional swimming bias. Most STS (80%; n = 41) predominantly utilized the top two-thirds of the enclosures, though 83% (n = 34) of those had swimming obstructions in the bottom of the enclosure. Avoidance of obstructed areas, sections <7 m wide, as well as behavioral spatial separation, resulted in utilization of between 27% and 66% of available enclosure space. STS underutilized corners, pinch-points, and obstructed areas requiring abrupt directional changes and instead exhibited continual, unimpeded swimming patterns. In addition, this study found no relationship between directional swimming bias or use of smaller enclosure volumes and spinal deformity, a health issue affecting 26% of STS 10 years ago but now with an incidence of 6%. Using novel protocols for three-dimensional mapping and volume estimation, this study demonstrated that enclosures facilitating unimpeded, continuous swimming are most usable for STS and provides important information that will be useful for future enclosure design.

Elevating performance in BDS-3 Precise Point Positioning Ambiguity Resolution through LEO augmented constellations

With the help of constellations combined BDS-3 (BeiDou Navigation Satellite System) and LEO (Low Earth Orbit), we aim to improve the performances of PPP (Precise Point Positioning) and PPP Ambiguity Resolution (PPP-AR). First, LEO constellations with 66, 96, 156, 192, 270, and 288 satellites are designed to establish six LEO augmented constellations. Based on four challenge scenarios, PPP of six LEO augmented constellations are performed. Even in the strip-shaped obstruction area losing more than 60% of observations, the positioning accuracies of static PPP are improved by (1.0%, 5.7%, 0.2%) for BDS+66LEO, and (14.9%, 33.7%, 7.5%) for BDS+288LEO in the east, north, and up components. The positioning accuracy and convergence time improve quickly as the number of LEO satellites increased from 66 to 156, and slowdown from 192 to 288. Two constellations, BDS+156LEO and BDS+192LEO, are considered to strike the balance of acceptable PPP performance and constellation load. Then, the performance of PPP-AR is realized with the estimated UPD (Uncalibrated Phase Delay). The correlations among geodetic parameters and ambiguities deriving from the post-fit variance–covariance matrix are analyzed to illustrate the enhancement of LEO augmented constellations. Under the condition of 20°elevation angle occlusion with azimuth ranging from 0 to 360°, BDS+156LEO can achieve an ambiguity fix rate of up to 98.37% with a faster mean TTFF (Time To First Fix) of 12.76 min, and the positioning accuracies in the east, north, and up components are improved by 28.2%, 21.4%, and 15.1% respectively, compared with BDS-3. BDS+192LEO realized an 98.42% ambiguity fixing rate, and improved BDS-3 by 31.4%, 26.7% and 11.5% with its TTFF been 12.25 min.

Case Study: Free Space Path Loss for Mobile Network and WLAN

Wireless communication systems transmit and receive information through free space. Thus, there are other factors to consider when designing a wireless communication system. One of those factors is Free space Path Loss (FPSL), which refers to the loss of signal strength in the propagation of the signal in free space. In this study, the effects of obstruction and distance on the FSPL of the transmission in mobile networks and Wireless Local Area Networks (WLAN) will be measured. The measured results show that the obstructions have a higher impact on the received signal compared to the distance. In the mobile network setting, the open area has an FPSL of 111 dB, whereas the obstructed office area has a significantly higher FSPL of 158 dB. Furthermore, in the WLAN setting, the FSPL of an obstructed area is 19 dB higher than the line-of-sight propagation. Thus, the layout of the area to implement a wireless communication system must be thoroughly analyzed for obstructions and distance to provide optimal wireless communication service to customers.

Two birds one stone: lymphatic and breast reconstruction with autologous tissue

Patients with breast cancer-related lymphedema (BCRL) commonly present with both debilitating upper extremity symptoms and the need for breast reconstruction. By combining autologous flaps with physiologic lymphatic surgery, postmastectomy patients with BCRL can obtain aesthetic breast reconstruction and lymphedema management in a single operation. Lymph node transfer to an area of lymphatic obstruction creates a healthy lymphatic bridge and restores physiologic flow. Early success and improved understanding of vascularized lymph node transfer (VLNT) physiology have led to the rapid development of numerous flap options and modalities. Several studies have shown the efficacy of combining autologous breast reconstruction with VLNT. Chimeric flaps using inguinal nodes, lateral thoracic nodes, or omentum aim to construct an aesthetic breast and improve lymphatic function. In this article, we will detail the surgical options that accomplish autologous breast reconstruction and restore the lymphatic network in a single operation.

Management of prosthetic valve thrombosis with unfractionated heparin

BackgroundProsthetic valve thrombosis (PVT) is a severe and life-threatening complication. Surgery and thrombolytic therapy (TT) carry a high risk, and in several circumstances, optimal anticoagulation with unfractionated heparin (UFH) infusion may be an alternative treatment. This study aimed to assess the results of UFH in patients diagnosed with both obstructive and non-obstructive PVT. MethodsThis observational retrospective study enrolled patients who had contraindications for TT and surgery underwent UFH therapy. ResultsA total of 136 patients were enrolled [male: 55 (40.4%), mean age: 50.3 ± 14.6 years] in the study. In the successful group, 66 patients (48,5%) showed >75% regression in the thrombus burden without facing death or major non-fatal complications.In the unsuccessful group, 56 had less than a 50% reduction in thrombus load and 14 (10.3%) suffered major complications. The presence of obstruction (27.1% vs. 12.1%; p = 0.028), thrombus area 1.1 cm2 vs. 0.8 cm2; p = 0.005] and the duration of UFH treatment (15.1 vs. 11.8 (days); p = 0.005) were significantly higher in the unsuccessful UFH group.In multivariate regression analyses the presence of obstruction (RR: 3.088, p = 0.020), increased thrombus area (RR: 2.400; p = 0.015), and increased duration of UFH therapy (RR: 1.073 95%, p = 0.012) were identified as independent predictive parameters for a failed UFH therapy. ConclusionsThis study suggests that UFH therapy may be considered a relatively beneficial treatment strategy for some patients with PVT. The most significant factors affecting success are the obstructive nature and area of the thrombus.

Towards field deployment of MAVs in adaptive exploration of GPS-denied subterranean environments

Exploration and safe navigation in previously unknown GPS-denied obstructed areas are major challenges for autonomous robots when deployed in subterranean environments. In response, this work establishes an Exploration-Planning framework developed for the real-world deployment of Micro Aerial Vehicles (MAVs) in subterranean exploration missions. The fundamental task for an autonomous MAV to navigate in an unknown area, is to decide where to look while navigating such that the MAV will acquire more information about the surrounding. The work presented in this article focuses around 3D exploration of large-scale caves or multi-branched tunnel like structures, while still prioritizing the Look-Ahead and Move-Forward approach for fast navigation in previously unknown areas. In order to achieve such exploration behaviour, the proposed work utilizes a two-layer navigation approach. The first layer deals with computing traversable frontiers to generate the look ahead poses in the constrained field of view, aligned with the MAV’s heading vector that leads to rapid continuous exploration. The proposed frontier distribution based switching goal selection approach allows the MAV to explore various terrains, while still regulating the MAV’s heading vector. The second layer of the proposed scheme deals with global cost based navigation of the MAV to the potential junction in a multi-branched tunnel system leading to a continuous exploration of partially seen areas. The proposed framework is a combination of a novel frontier goal selection approach, risk-aware expandable grid based path planning, nonlinear model predictive control and artificial potential fields based on local reactive navigation, obstacle avoidance, and control for the autonomous deployment of MAVs in extreme environments.

A comparative analysis of the performance of various GNSS positioning concepts dedicated to precision agriculture

Abstract Automated guidance systems for precision agriculture rely on Global Navigation Satellite Systems (GNSS) and correction services for high accuracy and precision in field operations. This study evaluates the performance of selected GNSS positioning services for precision agriculture in a field experiment. We use three correction services: SF1, SF3, and RTK, which apply varying positioning concepts, i.e., Wide Area Differential GNSS, Precise Point Positioning, and Real-Time Kinematics, respectively. The tractor is autonomously steered along multiple predefined paths located in open-sky areas as well as near the heavy tree cover. The reference route of the vehicle is determined by classical surveying. Tractor trajectories, a SF1 and SF3 corrections, are shifted from predefined straight paths, unlike in the case for RTK. Offsets of up to several decimeters are service- and area-specific, indicating an issue with the stability of the reference frame. Additionally, the varying performance of the correction services implies that environmental conditions limit the precision and accuracy of GNSS positioning in precision agriculture. The pass-to-pass analysis reveals that SF1 improves the declared accuracy, while SF3 is less reliable in obstructed areas. RTK remains a stable source for determining position. Under favorable conditions, the pass-to-pass accuracy at 95% confidence level is better than 11.5 cm, 8.5 cm, and 4.5 cm for SF1, SF3, and RTK, respectively. In the worst-case scenario, the corresponding accuracies are: 25.5 cm, 65.5 cm, and 22.5 cm.

Detection of Underground Dangerous Area Based on Improving YOLOV8

In order to improve the safety needs of personnel in the dark environment under the well, this article adopts the improved YOLOV8 algorithm combined with the ray method to determine whether underground personnel are entering dangerous areas and to provide early warning. First of all, this article introduces the coordinate attention mechanism on the basis of YOLOV8 target detection so that the model pays attention to the location information of the target area so as to improve the detection accuracy of obstruction and small target areas. In addition, the Soft-Non-Maximum Suppression (SNMS) module is introduced to further improve accuracy. The improved model is then combined with the ray method to be deployed and applied under a variety of angles and different scenic information cameras. The experimental results show that the proposed method obtains 99.5% of the identification accuracy and a frame speed of 45 Frames Per Second (FPS) on the self-built dataset. Compared with the YOLOV8 model, it has a higher accuracy and can effectively cope with the changes and interference factors in the underground environment. Further, it meets the requirements for real-time testing in dangerous underground areas.

Safety and efficacy of side-by-side versus stent-in-stent stenting for malignant hilar biliary obstruction: a systematic review and meta-analysis.

Stenting of the malignant hilar biliary obstruction (MHBO) area for bile drainage is challenging. Bilateral stenting techniques of stent-in-stent (SIS) and stent-by-stent (SBS) have shown promising results. This study evaluates the efficacy of different stenting methods for MHBO. A meta-analysis was performed to determine the efficacy of SIS and SBS stenting strategies for MHBO. Medical databases such as PubMed, Web of Science, Embase, and Scopus, were searched up to August 2023. We selected eligible studies reporting the data on technical and clinical success, adverse events, and incidence of re-obstruction (RO) of SBS and SIS groups in MHBO patients. We compared the outcomes of SBS and SIS groups. A total of 9 studies comparing the data of 545 patients (268 in the SBS group and 277 in the SIS stenting group) were analyzed. There was no significant difference (p > 0.05) in the odds ratio (OR) of Re-obstruction (RO) 0.87 (95% confidence interval (95% CI) 0.6-1.25), technical success 0.58 (95% CI 0.16-2.11), clinical success 1.13 (95% CI 0.62-2.07), and adverse events 1.53 (95% CI 0.88-2.64). The mean difference in procedure time was -12.25 min (95% CI -18.39, -6.12), and the hazard ratio of stent patency was 1.22 (95% CI 1.01-1.47), favoring SBS, with high heterogeneity (I 2 = 94%). There was no significant difference in HR for survival 1.05 (95% CI 0.95-1.16) with high heterogeneity (I 2 = 84%). Compared with SIS, SBS showed better stent patency with comparable technical and clinical success and adverse events. The registration number for this study on PROSPERO is CRD42024523230.

Combining Hough Transform and Fuzzy Unsupervised Learning Strategy in Automatic Segmentation of Large Bowel Obstruction Area from Erect Abdominal Radiographs

Combining Hough Transform and Fuzzy Unsupervised Learning Strategy in Automatic Segmentation of Large Bowel Obstruction Area from Erect Abdominal Radiographs

Pulsatile blood flow simulations of magnetic drug targeting (MDT) for drug particles dispersion through stenosis asymmetric and symmetric vessels

Magnetic drug delivery has emerged as an innovative strategy for addressing medical conditions like tumors and vascular occlusions. In this study, we delve into the influence of magnetic fields on three-dimensional models representing various vessel configurations, including unobstructed, asymmetric, and symmetric vessels. We take into account critical factors such as non-Newtonian viscosity, pulsatile flow, and the presence of vessel obstructions. By investigating drug particles ranging from 1 to 4 µm in diameter, our findings illuminate the central role that magnetic particles play in Magnetic Drug Targeting (MDT). Importantly, we observe a substantial enhancement in drug particle capture efficiency in the presence of a magnetic field, particularly for larger particle diameters. Nevertheless, this efficiency saturates at 100% for diameters exceeding 3 µm due to particle–wall interactions. Interestingly, within potential obstruction areas, particle capture efficiency exhibits a nuanced relationship with diameter. Even at a diameter of 4 µm, the magnetic field's influence on vessel walls leads to particle capture before reaching obstructions, thus reducing efficiency. Comparing scenarios without a magnetic field, it is found that symmetrical obstructions yield higher capture efficiency compared to asymmetrical vessels, and asymmetric vessels outperform their smoother counterparts. Moreover, the presence of vessel obstructions amplifies drug particle capture efficiency. Consequently, our simulations unveil significant potential for the application of MDT in the treatment of atherosclerosis. From a physics perspective, these results offer promising prospects for the application of Magnetic Drug Targeting in the realm of cardiovascular diseases.

Cardiac extracellular matrix at microvascular obstruction area after reperfused myocardial infarction: a morphometric study

Abstract Background Extracellular matrix (ECM), a structural and biomechanical support to cardiomyocytes, suffers substantial alterations after myocardial infarction (MI). Despite a complete reopening at epicardial level, hypoperfusion within the infarcted myocardium, known as microvascular obstruction (MVO), occurs. Extensive clinical studies and meta-analysis reported the association between the magnitude of MVO and the appearance of adverse remodeling; thus, scrutinizing ECM composition within the infarcted areas with impaired tissue-level reperfusion could provide fundamental insight regarding MVO pathophysiology. Purpose To histologically compare ECM composition within the infarct zone regarding the presence or absence of MVO using an experimental swine model of reperfused MI. Methods MI was induced in swine (n=10) by transitory 90-min coronary occlusion followed by 7 days of reperfusion. Prior to euthanasia, intracoronary thioflavin-S was infused. Within the infarcted myocardium, regions displaying MVO (thioflavin-S-) or no MVO (thioflavin-S+) were isolated and stained to morphometrically compare ECM composition. Results Regarding cellularity, areas with MVO displayed an enlarged presence of neutrophils and lymphocytes, whilst no differences in the amount of macrophages and myofibroblasts were detected in comparison to no MVO-myocardium. Those regions with macroscopic MVO showed lower capillary density than those without MVO. According to the fibers and ground substance, a significant reduction in the extension of type I collagen, laminin, and fibronectin together with an augmentation of glycosaminoglycan were noted in areas showing MVO compared to those without microvascular injury. No changes in the amount of type III collagen was observed. Conclusion The ECM composition in infarcted regions with MVO displays a higher presence of inflammatory infiltrate and glycosaminoglycans as well as a reduced amount of microvessels and fibers compared to those areas without microvascular hypoperfusion. These characteristics might underlie the development of adverse ventricular remodeling in MI patients with extensive MVO.

Deep-Reinforcement-Learning-Based Joint 3-D Navigation and Phase-Shift Control for Mobile Internet of Vehicles Assisted by RIS-Equipped UAVs

Unmanned aerial vehicles (UAVs) are utilized to improve the performance of wireless communication networks (WCNs), notably, in the context of Internet-of-things (IoT). However, the application of UAVs, as active aerial base stations (BSs)/relays, is questionable in the fifth-generation (5G) WCNs with quasi-optic millimeter wave (mmWave) and beyond in 6G (visible light) WCNs. Because path loss is high in 5G/6G networks that attenuate, even, the line-of-sight (LoS) communicating signals propagated by UAVs. Besides, the limited energy/size/weight of UAVs makes it cost-deficient to design aerial multi-input/output BSs for active beamforming to strengthen the signals. Equipping UAVs with the reconfigurable intelligent surface (RIS), a passive component, can help to address the problems with UAV-assisted communication in 5G and optical 6G networks. We propose adopting the RIS-equipped UAV (RISeUAV) to provide aerial LoS service and facilitate communication for mobile Internet-of-vehicles (IoVs) in an obstructed dense urban area covered by 5G/6G. RISeUAV-aided wireless communication facilitates vehicle-to-vehicle/everything communication for IoVs for updating IoT information required for sensor fusion and autonomous driving. However, autonomous navigation of RISeUAV for this purpose is a multilateral problem and is computationally challenging for being optimally implemented in real-time. We intelligently automated RISeUAV navigation using deep reinforcement learning to address the optimality and time complexity issues. Simulation results show the effectiveness of the method.

Laser ureteroscopic endopyelotomy efficacy in pyeloureteral junction stenosis

Introduction. Pyeloureteral junction stenosis (PUJS) is a condition that affects urinary drainage at level of the renal pelvis and upper ureter. It is found in approximately 1 in 500 newborns, with a higher prevalence in males (2:1 ratio). PUJS is the main cause of congenital hydronephrosis and can also be caused by other specific pathologies. Endoscopic management is the primary treatment for PUJS, particularly in cases of aperistaltic and &lt;2cm intrinsic ureteral stenosis without aberrant vessels. Aim of the study. Efficacy assessment of endoscopic retrograde incision of PUJS for urinary drainage recovery and duration of postoperatory effect. Material and methods. 5 patients were operated, from November 2022 to February 2023. Each patient has been operated by using retrograde LASER endopyelotomy method. There were excluded patients with extrinsic ureteral obstruction, defected segment more than 2 cm, massive hydronephrosis, split renal function &lt;20%, tumor in the obstruction area, high ureteral insertion, patients &lt;18 years of age. Mean follow-up time of patients is 8 weeks. Results. One month after intervention patients were recalled for investigations. There were observed way more better results in the patients with grade 1 hydronephrosis than those with grade 2 (p = 0.002). All patients at 3-month postoperative follow-up reported resolution of symptoms. Conclusions. Efficacy of LASER endopyelotomy is 99.9% in first months of the follow-up, after double J stent extraction. More follow-up time and patients are required to present more statistically significant results.

Marine Collision Avoidance Route Planning Model for MASS Based on Domain-Based Predicted Area of Danger

When the own ship encounters target ships in a close-quarter situation, an officer on watch needs to safely and timely alter the course of the vessel to avoid a collision. If ECDIS can automatically collect the navigation parameters and plot areas of collision as quasi-static obstruction areas, it will be much easier for seafarers to implement effective route planning. Hence, this study focuses on developing the MCARP model as a theoretical concept based on the DPAD model and LCD model. By operating the MCARP using ArcGIS, DPADs and several effective collision avoidance routes can be generated and imported into ECDIS based on AIS information at large scales and ample time. The graphic overlay of DPADs and effective routes on ECDIS can serve as a collision avoidance strategy reference for the personnel controlling maritime autonomous surface ships. Finally, different ships encountering situations were input into a Transas navigational simulator. The simulation results showed that own ship could avoid collisions with multiple target ships at distances larger than the preset collision avoidance distances, which also indicated that MCARP is practically feasible.

Changes in the extracellular matrix at microvascular obstruction area after reperfused myocardial infarction: A morphometric study

BackgroundExtracellular matrix (ECM) suffers substantial alterations after myocardial infarction (MI), including the invasion of leukocyte subtypes. Despite a complete reopening at epicardial level, hypoperfusion within the infarcted myocardium, known as microvascular obstruction (MVO), occurs and exerts a negative impact on ventricular remodeling. In this study, ECM composition at MVO regions was described using a morphometric analysis. MethodsMI was induced in female swine (n = 10) by transitory 90-minute coronary occlusion followed by seven days of reperfusion. Prior to euthanasia, intracoronary thioflavin-S was infused. Within the infarcted myocardium, regions displaying MVO (thioflavin-S-) or no MVO (thioflavin-S+) were isolated and stained to morphometrically compare ECM composition. ResultsAs reflected by cell invasion through ECM, areas with MVO displayed an enlarged presence of neutrophils and lymphocytes, whilst no differences in the amount of macrophages and myofibroblasts were detected compared to infarcted myocardium without MVO. Indeed, those regions with macroscopic MVO showed lower capillary density than areas without MVO. Lastly, a significant reduction in the extension of total collagen, type I, but not type III, collagen, laminin, and fibronectin together with an augmentation of polysaccharides were noted in areas showing MVO compared to those without microvascular injury. ConclusionsECM composition in infarcted regions with MVO isolated from female swine displays a higher presence of inflammatory infiltrate and polysaccharides as well as reduced number of microvessels and collagen content compared to those areas without microvascular hypoperfusion. These characteristics might underlie the development of adverse ventricular remodeling in MI patients with extensive MVO.

REF: A Rapid Exploration Framework for Deploying Autonomous MAVs in Unknown Environments

Exploration and mapping of unknown environments is a fundamental task in applications for autonomous robots. In this article, we present a complete framework for deploying Micro Aerial Vehicles (MAVs) in autonomous exploration missions in unknown subterranean areas. The main motive of exploration algorithms is to depict the next best frontier for the MAV such that new ground can be covered in a fast, safe yet efficient manner. The proposed framework uses a novel frontier selection method that also contributes to the safe navigation of autonomous MAVs in obstructed areas such as subterranean caves, mines, and urban areas. The framework presented in this work bifurcates the exploration problem in local and global exploration. The proposed exploration framework is also adaptable according to computational resources available onboard the MAV which means the trade-off between the speed of exploration and the quality of the map can be made. Such capability allows the proposed framework to be deployed in subterranean exploration and mapping as well as in fast search and rescue scenarios. The performance of the proposed framework is evaluated in detailed simulation studies with comparisons made against a high-level exploration-planning framework developed for the DARPA Sub-T challenge as it will be presented in this article.