Deep Position Research Articles

Comparative study on real-time pose estimation of vision-based unmanned underwater vehicles

Background: Navigation and localization are key to the successful execution of autonomous unmanned underwater vehicles (UUVs) in marine environmental monitoring, underwater 3D mapping, and ocean resource surveys. The estimation of the position and the orientation of autonomous UUVs are a long-standing challenging and fundamental problem. As one of the underwater sensors, camera has always been the focus of attention due to its advantages of low cost and rich content information in low visibility waters, especially in the fields of visual perception of the underwater environment, target recognition and tracking. At present, the visual real-time pose estimation technology that can be used for UUVs is mainly divided into geometry-based visual positioning algorithms and deep learning-based visual positioning algorithms. Methods: In order to compare the performance of different positioning algorithms and strategies, this paper uses C++ and python, takes the ORB-SLAM3 algorithm and DF-VO algorithm as representatives to conduct a comparative experiment and analysis. Results: The geometry-based algorithm ORB-SLAM3 is less affected by illumination, performs more stably in different underwater environments, and has a shorter calculation time, but its robustness is poor in complex environments. The visual positioning algorithm DF-VO based on deep learning takes longer time to compute, and the positioning accuracy is more easily affected by illumination, especially in dark conditions. However, its robustness is better in unstructured environments such as large-scale image rotation and dynamic object interference. Conclusions: In general, the deep learning-based algorithm is more robust, but multiple deep learning networks make it need more time to compute. The geometry-based method costs less time and is more accurate in low-light and turbid underwater conditions. However, in real underwater situations, these two methods can be connected as binocular vision or methods of multi-sensor combined pose estimation.

Isolated Trochlear Fracture Of The Humerus

The fracture of the distal part of the humerus usually involves the capitellum and variable part of the trochlea. The deep position of the trochlea within the elbow joint makes it a rare occurrence and protects it from direct damage. A 23-year- old local man named Mumtaz presented with an intra-articular half-moon-shaped fragment that had traveled and forward, leading us to assume a capitellar fracture. That was fixed through the medial approach of distal humerus. Postoperatively, patient a had good pain-free range of motion.

Distribution of bone tunnel positions and treatment efficacy of bone landmark positioning method for anatomical reconstruction of the anterior cruciate ligament: a case control study

BackgroundThis study aimed to investigate the distribution of femoral tunnel and explore the influences of bone tunnel positions on knee functions. The bone landmark positioning method was used to position the femoral tunnel during the anatomical reconstruction surgery in patients with anterior cruciate ligament (ACL) rupture.MethodsData of patients who underwent anatomical reconstruction of the ACL between January 2015 and July 2018, were retrospectively analyzed. The distribution of the femoral tunnel was recorded on 3-D CT after surgery. The tunnel positions were classified into good and poor position groups based on whether the position was in the normal range (24–37% on the x-axis and 28–43% on the y-axis). The Lysholm and IKDC scores, KT-1000 side-to-side difference, pivot shift test and Lachman test results of the knee joints were recorded, and then the differences in knee joint functions between the two groups were analyzed.Results84 eligible patients (84 knees) were finally included in this study. Twenty-two and 62 of the patients were categorized in the good and poor position groups, respectively, and the rate of good position was 26.2%. The distribution of bone tunnel was as follows: (x-axis) deep position in 10 patients (12%), normal position in 58 patients (69%), and shallow position in 16 patients (19%); (y-axis) high position in 54 patients (64%), normal position in 26 patients (31%), and low position in 4 patients (5%). 1 year later, the Lysholm and IKDC scores were significantly better in the good position group (P < 0.05), the KT-1000 side to side difference, the pivot shift test and Lachman test results were better in the good position group (P < 0.05).ConclusionsThe bone tunnels were found to be distributed in and beyond the normal range using the bone landmark method to position the femoral tunnel in the single-bundle anatomical reconstruction of ACL, while the rate of good bone tunnel position was low. The knee joint function scores and stability were lower in patients with poor position of the femoral tunnel.

Reduction of Forward Bias Degradation in 4H-SiC PiN Diodes Fabricated on 4H-SiC Bonded Substrates

The advantage in reducing forward bias degradation of bipolar 4H-SiC devices using a 4H-SiC bonded substrate is demonstrated. To evaluate the differences in forward bias degradation between a 4H-SiC bonded substrate and a commercially available 4H-SiC bulk substrate, a forward current stress test and subsequent photoluminescence (PL) imaging of PiN diodes fabricated on both the substrates were performed. Unlike the bulk substrate, the bonded substrate maintained a low ΔVf and the variation among the measured diodes was extremely small even after applying the highest current density of 1500 A/cm2. The investigated number of bar-shaped SSFs within the electrically stressed diodes with more than 1000 A/cm2 revealed the possibility that the BPDs existing at deep positions below the epilayer/substrate interface were drastically reduced in the 4H-SiC bonded substrate.

Papua New Guinea Moho inversion based on XGM 2019e gravity field model

The construction of the high-resolution Moho depth model is significant for studying the characteristics of the complex tectonic movement (seafloor spreading, plate subduction phenomena) in Papua New Guinea. We calculate the region’s Moho relief and lithosphere thinning factor using the XGM 2019e gravity field model and nonlinear fast gravity inversion method under the GEMMA Moho depth model’s constraint considering the influence of lithosphere thermal gravity anomaly. The calculation result shows that the Moho depth is between 6—34 km, forming two large depressions in Woodlark Basin (WB) and Solomon Sea Plate (SSP) with deep scattered islands. In addition, the findings suggest that Significant differences exist in the shape and tectonic movement intensity of the North and South oceanic crust at the WB. Nevertheless, the lithosphere extends evenly in Manus Basin (MB). WB collided with the Solomon Islands at a higher angle than the SSP subducted under Bismarck Sea Plate (BSP); strong earthquakes may frequently occur on both sides and in deeper positions at West New Britain Trench in the future.

Modeling stoichiometric and oxygen defective TiO2 anatase bulk and (101) surface: structural and electronic properties from hybrid DFT.

We present a periodic hybrid DFT investigation of the structural and electronic properties of both stoichiometric and oxygen-defective TiO2 anatase bulk and (101) surface, in singlet and triplet spin states. In all cases, an excellent agreement with available photoelectron spectroscopy data has been obtained, reproducing the offsets of the deep defect levels positions from the conduction band minimum of TiO2 created upon oxygen vacancy (VO) formation. For the bulk, different local structural polaronic distortions around the VO site have been evidenced depending on the spin state considered. Although a similar conclusion has been drawn for the defective surface for the nine different vacancy positions which have been considered, large migration of the twofold coordinated surface O atom has also been evidenced, up to the initial vacancy site in some cases. The very good agreement obtained with available experimental data regarding the offsets from the conduction band minimum of the deep defect levels positions both for the bulk and the (101) surface of TiO2 anatase is encouraging for the application of the proposed hybrid-based computational strategy to TiO2 surface-related processes such as TiO2-based photocatalysis in which oxygen vacancies are known to play a key role. All calculations have been performed with Crystal17, considering different hybrid functionals with both effective core pseudopotentials and all-electron atom-centered basis sets, as well as additional empirical dispersion effects with the D2 and D3 models.

Prewinter soil water regime affects the post-winter cracking position on gully sidewall and slumping soil dynamics in Northeast China

Gully erosion is one of the most destructive land degradation processes. Soil slumping along cracks on a gully sidewall is a crucial process of gully development, yet the factors controlling the dynamics and amount of slumped soil remain unclear. It was hypothesized that soil slumping along the cracks in summer might be affected by the prewinter soil water regime, as it determines the depth of freezing-induced fissures within the soil profile, which affects the depth and dynamics of the cracks on the gully sidewall. To test this hypothesis, the soil water regime was manipulated by infiltrating 250 mm of water into the plots placed with one edge 10, 30 and 50 cm away from a gully sidewall before winter. This plot layout eventually resulted in four treatments with different amounts of infiltrated water. The isolines of near-saturation soil water contents appeared closer to the ground and the sidewall under the higher infiltration treatments before and after winter. Soil freezing started from the topsoil on 14 Nov. 2017 and penetrated the 1-m soil profile within 24 days. Soil thawing started from both the topsoil and subsoils (1 m depth) on 13 Apr. 2018 and ended on 24 Apr. 2018. The cracks that appeared on the sidewalls in Apr. had similar lengths and widths at the depths with a near-saturation soil water content (between 25 and 45 g kg−1). The cracks appeared at deeper position on gully sidewall under lower infiltration treatments. The soil mass slumped from the sidewall was greater in Apr. and less from Jul. to Aug. under higher infiltration treatments. The annual total of slumped soil mass was the lowest in the low infiltration treatment, where the near-saturation isolines were the deepest. These findings suggested that the prewinter soil water regime along the slope controlled the depth of freezing within the soil profile. The freezing depth determined the depth and time of soil cracking and slumping on the gully sidewalls the following year. Our study implies that gully development through soil slumping depends on pre-winter slope hydrology, which should be considered in modeling and controlling gully development.

Geophysical Characterization and Attenuation Correction Applied for Hydrate Bearing Sediments in Japan Sea

Estimation of rock properties from seismic data is important for exploration and production activities in the petroleum industry. Considering the compressional velocity—the speed of propagating body waves in formations—and the quality factor (Q)—a measure of the frequency-selective energy losses of waves propagating through formations—both properties are usually estimated from multichannel seismic data. Velocity is estimated during multichannel processing of seismic reflection data in either the time or depth domain. In marine seismic acquisition, Q can be estimated from the following sources: Vertical Seismic Profile (VSP) surveys, where sources are located near the sea surface and geophones are distributed at depth along a borehole; and multichannel reflection data, where sources are also located near the sea surface and receivers are distributed either at the sea surface (conventional seismic survey with streamers) or on the sea floor (use of nodes or Ocean Bottom Cables (OBC)). The aforementioned acquisition devices, VSP, conventional streamers, nodes, and OBCs are much more expensive than single-channel acquisition with one receiver per shot due to the cost of operation. There are numerous old and new datasets from academia and the oil industry that have been acquired with single-channel acquisition devices. However, there is a paucity of work addressing the estimation of velocity and Q from this type of equipment. We investigate the estimation of Q and velocity from single-channel seismic data. Using the windowed discrete Fourier transform for a single seismic trace, we calculate the peak and dominant frequency that changes with time. In the geologic environment, higher frequencies are attenuated at shallow depths (time), while lower frequencies remain at deeper positions. From the rate at which higher frequencies are attenuated with time, we estimate the effective quality factor (Qeff). However, when using Kirchhoff migration to process single-channel seismic data, events far from the vertical projection of the receiver contribute to the trace at a given time. Then, an underestimation of the effective quality factor occurs. To compensate for the effects of more distant events with lower-frequency content contaminating the shorter events, we propose a linear equation to correct the effective quality factor estimated from migrated seismic data. Effective Q and its correction are estimated in five single-channel seismic lines surveyed along the Joetsu Knoll, a SW-NE anticline structure on the eastern margin of the Sea of Japan. These results are linked to geomorphological and geological features and the velocity field. Joetsu Knoll is a known site of massive gas hydrates (GH), which occur in the first hundred metres of Neogene sediments and, together with gas chimneys, play an important role in seismic wave absorption. Qeff estimated from migrated seismic data maintains the spatial relationship between high and low Q regions. The region of low Q, which is below 124 and has an average value of 57, occurs near the anticlinal hinge and tends to coincide with the region in which the Bottom Simulating Reflector (BSR) resides. The coexistence of GH and free gas coincides with the very low P velocity gradient of 0.225 s−1. BSR occurrence, Qeff and the geometry of the Joetsu anticline testify to progressive gas hydrate depletion northward along the dome.

Role of magnetic resonance neurography in assessment of lumbosacral radiculo-plexopathy: correlation with electrophysiological studies

BackgroundLumbosacral plexus is a collection of nerves that converge and diverge and finally merge into terminal nerves that innervate the pelvis and lower limbs. Lumbosacral plexopathy is a clinical disease characterized by motor and sensory abnormalities that can result from damage to the lumbosacral plexus by different types of insults. Electrophysiological studies are used to demonstrate the presence of lumbosacral radiculo-plexopathy, but it is restricted owing to deep position of nerves and regional differences in muscle nerve supply. High-resolution MR neurography can simply show the precise site, size, etiology, and type of the lumbosacral radiculo-plexopathy. The aim of this study was to assess the various diseases affecting the lumbosacral plexus with their 1.5-T MR neurography imaging findings and to correlate these findings with electrophysiological studies.ResultsFifty adult patients with clinical presentation of lumbosacral radiculo-plexopathy were included in this cross-sectional study. Based on clinical diagnosis, the sensitivity of electrophysiological studies in diagnosing lumbosacral radiculo-plexopathy was 80% and the sensitivity of MR neurography in diagnosing lumbosacral radiculo-plexopathy was 90%. While based on electrophysiological studies, the sensitivity of MR neurography in diagnosing lumbosacral radiculo-plexopathy was 97.5% and the specificity was 75.86%. There was a high statistically significant relation between the side affected in electrophysiological studies and the side affected in MR neurography and between the stage of the lesion in the electrophysiological studies and in MR neurography among patients (p ≤ 0.001, p ≤ 0.001) , respectively.ConclusionsMR neurography of the lumbosacral plexus is a helpful non-invasive approach for the assessment of patients with inconclusive lumbar spine MR imaging because of its ability for diagnosis of neuromuscular lesions and determining their causes. Electrophysiological studies assess the nerve function and MR neurography assesses the nerve anatomy, and therefore, the correlation between electrophysiological studies and MR neurography are complementary for detection of lumbosacral radiculo-plexopathy.

Paleoceanographic Implications of Diatom Seasonal Laminations in the Upper Miocene Pisco Formation (Ica Desert, Peru) and Their Clues on the Development of the Pisco Fossil‐Lagerstätte

AbstractThe detailed study of diatom laminations conducted by means of backscattered electron imaging serves as tool to unravel details of past ocean dynamics. In this paper we apply this method to the analysis of the diatomites of Cerro Los Quesos, Upper Miocene Pisco Fm, Peru. Numerous studies have been conducted on the Pisco Fm; however, a focus on its paleoceanographic significance is still lacking. In this work, we provide information on the oceanographic setting in the area at the time of diatomites deposition. The high abundance of deep‐living Coscinodiscus laminae, proceeded by either a mixed lamina or a terrigenous one, let us hypothesize a deep position of the thermocline during the deposition of the Pisco diatomites; together with the scarcity of Chaetoceros Hyalochaete spp. resting spores, this evidence confutes the belief that equals high biogenic silica content in marine sediments with enhanced upwelling. Conversely, the depositional setting of the Pisco Fm diatomites is more similar to what is known as “permanent El Niño” (or “El Padre”) state, meaning a constant weakened upwelling (or upwelling of nutrients‐poor waters). Climate modeling warns that an increase in atmospheric CO2 may lead to this mean state in the near future. Thanks to this study we also obtained refined information on the diatomites sedimentations rates. The comparison of the Pisco diatomites sedimentation rates with those of Quaternary diatomites gave strength to the hypothesis that the formation of the vertebrate Lagerstätte may have been enhanced, among others, by the so‐called “impact‐burial” mechanism.

Precision Mapping of Thalamic Deep Brain Stimulation Lead Positions Associated With the Microlesion Effect in Tourette Syndrome.

The microlesion effect refers to the improvement of clinical symptoms after deep brain stimulation (DBS) lead placement and is suggested to indicate optimal lead placement. Very few studies have reported its implications in neuropsychiatric disorders. To evaluate the magnitude of the microlesion effect in Tourette syndrome and the relationship between the microlesion effect and the anatomic location of implanted DBS leads. Six male patients were included. Their median age at surgery and follow-up period were 25 years (range, 18-47) and 12 months (range, 6-24), respectively. All patients were videotaped pre- and postoperatively, and tic frequencies were counted. We also analyzed the precision of lead placement and evaluated the normative connectome associated with the microlesion area. The microlesion effect was observed as an improvement in tic symptoms in all patients, and the long-term clinical outcomes were favorable. The median motor tic frequency was 20.2 tics/min (range, 9.7-60) at baseline and decreased to 3.2 tics/min (1.2-11.3) in patients on postoperative day 1 ( P = .043) and to 5.7 tics/min (range, 1.9-16.6) in patients on postoperative day 7 ( P = .028). Phonic tic tended to improve immediately after surgery although the changes were not significant. Image analyses revealed that the precise position of the electrode was directed toward the anteromedial centromedian nucleus. Normative connectome analysis demonstrated connections between improvement-related areas and wide areas of the prefrontal cortex. This study shows that the microlesion effect may seem as an immediate improvement after optimal DBS lead placement in patients with Tourette syndrome.

Isolated Duodenal Perforation at D3 Following Blunt Abdominal Trauma, a Challenging Diagnosis and Management: A Case Report

Introduction: Isolated duodenal rupture following blunt abdominal trauma is rare. We here report a case of isolated duodenal perforation treated by suture, pyloric exclusion and side-to-side gastrojejunostomy in order to discuss its diagnostic, therapeutic, and evolutionary features. Observation: A 46-year-old man, victim of a physical aggression, consulted ten hours after the trauma for diffuse abdominal pain associated with vomiting. The physical examination revealed a febrile patient at 38.2°C, hemodynamically stable with generalized abdominal defense. The abdominal CT revealed parietal defect of the 3rd duodenum (D3), pneumoperitoneum, intra and retroperitoneal fluid effusion without adjacent organ involvement. The patient underwent emergency surgery. Intraoperatively, a centimetric perforation of D3 on the anterior wall was found. The lacerated edges were repaired with interrupted sutures. A pyloric exclusion and side- to-side gastrojejunostomy are performed. Postoperative course of patient was unremarkable. Isolated duodenal injuries are rares in blunt abdominal trauma because the duodenum is located in a deep anatomical position. Duodenal injuries secondary to blunt trauma can range in severity from intramural hematoma to a complete transection and devascularization of the duodenum. There is no consensus on the surgical procedure. Options range from primary suture to complex duodenopancreatic resections based on the severity of the lesions. Conclusion: Isolated duodenal trauma is unusual following blunt trauma. Prompt diagnosis and management is the key to prevent morbidity and mortality.

Novel BiOBr/Bi2S3 high-low junction prepared by molten salt method for boosting photocatalytic degradation and H2O2 production

The molten salt method focuses on improving the crystallinity of synthetic materials and avoiding the high energy consumption of traditional synthesis processes. In this work, a novel BiOBr/Bi2S3 high-low junction with large contact area was constructed by the molten salt method combined with the ion exchange strategy. Its unique energy band structure and new charge transfer mechanism realize the rapid migration of photogenerated charges between different components. Specifically, Bi2S3 was grown on BiOBr in situ by a high-temperature molten salt reaction. Due to the deep valence band position of BiOBr and the narrow band gap of Bi2S3, an intrinsic internal electric field and band bending are produced at the interface, forming a high-low junction photocatalyst with an intimate interface. In addition, the BiOBr/Bi2S3 composite maintains a high oxidation potential and produces high and robust photocatalytic oxidation activity. In the molten state, the close binding of BiOBr and Bi2S3 can be promoted through the ion-exchange strategy, resulting in excellent photocatalytic degradation rates of bisphenol A and tetracycline and in-situ generation of H2O2. Finally, the mechanism of carriers separation and transfer in BiOBr/Bi2S3 high-low junction is also discussed. Density functional theory (DFT) results found that the improvement of O2 adsorption ability would promote the occurrence of oxygen reduction reaction (ORR), and make positive contributions to the enhanced H2O2 production activity. This study will provide a new perspective for broadening the spectral response range of Bi-based photocatalytic materials and preparing high-low junction photocatalysts with dense interface by the molten salt method.

Crystalline phase control of BiVO4 thin films using RF sputtering

A selective fabrication method for monoclinic-scheelite (m-s) BiVO4 and tetragonal-zircon (t-z) BiVO4 thin films using radio fRequency (RF) sputtering from a single target was developed. The kinetic energy of the sputtered atoms was controlled by varying the sputtering power to obtain BiVO4 films with m-s and t-z crystalline phases. Although the band gap of the t-z BiVO4 phase (3.0 eV) was larger than that of m-s BiVO4 (2.5 eV), the deposited t-z BiVO4 films showed a comparable photocurrent density (1.5 mA cm−2) at 1.23 V versus the reversible hydrogen electrode (400 W Xe lamp). This was mainly because of the reduced sputtering damage in the t-z BiVO4 crystal, which originated from the low sputtering power as well as the deep valence-band position in t-z BiVO4 that enabled the efficient utilization of the photocarriers. This work provides insights into crystalline phase control using the particle kinetic energy in sputtering.

Geophysical study of the Earthʼs crust (Northern regions of Russia and the Arctic sea shelf)

Research subject. The results of the geological and geophysical study of the Earth’s crust on the territory of two regions are presented: the northwestern part of the East European Platform and the adjacent water area, as well as the waters of the East Siberian, Chukchi Seas and the Russian eastern sector of the Arctic Ocean, including the Lomonosov ridge and the Mendeleev–Alpha rise. The research is focused on mapping the Moho, the thickness and type of the Earth's crust necessary to substantiate the outer boundary of the continental shelf.Materials and methods. The authors’ original materials obtained during the processing of gravimetry and magnetometry data in the VECTOR system were used. Based on the relationship between gravity anomalies and density variations of rocks, the shape, size of the studied objects, and their deep mutual position are characterized.Results. The constructed schemes and profiles of the deep structure of the Earth's crust, obtained using the VECTOR method, were tested using the European Moho global seismic model. The positive forms of the Moho section and the raised parts of the shelf surface correspond to the positive anomalies of the transformed gravitational field. The spread of the structure of the field of continental anomalies in the Pevek–Anadyr area to the marine part of the territory under consideration can indirectly confirm the belonging of the Lomonosov Cr., the Mendeleev and Alpha ridges to the continental type of crust.Conclusion. Global, i.e., related to the territory of the globe, three-dimensional models of Moho allow us to expand and deepen the amount of knowledge about the features of the shelf structure. Geopotential fields in the VECTOR system display the tectonics of the studied environment systematically and comprehensively compared to is representation according to the scheme of profile seismic studies.

A novel UAV-integrated deep network detection and relative position estimation approach for weeds

This paper aims at presenting a novel monocular vision–based approach for drones to detect multiple type of weeds and estimate their positions autonomously for precision agriculture applications. The methodology is based on classifying and detecting the weeds using a proposed deep neural network architecture, named fused-YOLO on the images acquired from a monocular camera mounted on the unmanned aerial vehicle (UAV) following a predefined elliptical trajectory. The detection/classification is complemented by a new estimation scheme adopting unscented Kalman filter (UKF) to estimate the exact location of the weeds. Bounding boxes are assigned to the detected targets (weeds) such that the centre pixels of the bounding box will represent the centre of the target. The centre pixels are extracted and converted into world coordinates forming azimuth and elevation angles from the target to the UAV, and the proposed estimation scheme is used to extract the positions of the weeds. Experiments were conducted both indoor and outdoor to validate this integrated detection/classification/estimation approach. The errors in terms of misclassification and mispositioning of the weeds estimation were minimum, and the convergence of the position estimation results was short taking into account the affordable platform with cheap sensors used in the experiments.

Risk factors for and consequences of difficult fetal extraction in emergency caesarean section. A retrospective registry-based cohort study

IntroductionThis study aimed to assess risk factors for difficult fetal extraction in emergency caesarean sections, focusing on top-up epidural anesthesia compared to spinal anesthesia. Additionally, this study addressed consequences of difficult fetal extraction on neonatal and maternal morbidity. Material and MethodsThis retrospective registry-based cohort study included 2,332 of 2,892 emergency caesarean sections performed with local anesthesia during 2010–2017. Main outcomes were analyzed by crude and multiple adjusted logistic regression providing odds ratios. ResultsDifficult fetal extraction was found in 14.9% of emergency caesarean sections.Risk-factors for difficult fetal extraction included top-up epidural anesthesia (aOR:1.37[95 %CI 1.04–1.81]), high pre-pregnancy BMI (aOR:1.41[95 %CI 1.05–1.89]), deep fetal descent (ischial spine: aOR:2.53[95 %CI 1.89–3.39], pelvic floor: aOR:3.11[95 %CI 1.32–7.33]), and anterior placental position (aOR:1.37[95 %CI 1.06–1.77]). Difficult fetal extraction was associated with increased risk of low umbilical artery pH 7.00–7.09 (aOR:3.50[95 %CI 1.98–6.15]) pH ≤ 6.99 (aOR:4.20[95 %CI 1.61–10.91]), five-minute Apgar score ≤ 6 (aOR:3.41[95 %CI 1.49–7.83]) and maternal blood loss (501–1,000 ml: aOR:1.65[95 %CI 1.27–2.16], 1,001–1,500 ml: aOR:3.24[95 %CI 2.24–4.67], 1,501–2,000 ml: aOR:3.94[95 %CI 2.24–6.94] and ≥ 2001 ml: aOR:2.76[95 %CI 1.12–6.82]). ConclusionThis study identified four risk factors for difficult fetal extraction in emergency caesarean section: top-up epidural anesthesia, high maternal BMI, deep fetal descent and anterior placental position. Additionally, difficult fetal extraction was associated with poor neonatal and maternal outcomes.

Mineral surface area in deep weathering profiles reveals the interrelationship of iron oxidation and silicate weathering

Abstract. Mineral specific surface area (SSA) increases as primary minerals weather and restructure into secondary phyllosilicate, oxide, and oxyhydroxide minerals. SSA is a measurable property that captures cumulative effects of many physical and chemical weathering processes in a single measurement and has meaningful implications for many soil processes, including water-holding capacity and nutrient availability. Here we report our measurements of SSA and mineralogy of two 21 m deep SSA profiles at two landscape positions, in which the emergence of a very small mass percent (&lt;0.1 %) of secondary oxide generated 36 %–81 % of the total SSA in both drill cores. The SSA transition occurred near 3 m at both locations and did not coincide with the boundary of soil to weathered rock. The 3 m boundary in each weathering profile coincides with the depth extent of secondary iron oxide minerals and secondary phyllosilicates. Although elemental depletions in both profiles extend to 7 and 10 m depth, the mineralogical changes did not result in SSA increase until 3 m depth. The emergence of secondary oxide minerals at 3 m suggests that this boundary may be the depth extent of oxidation weathering reactions. Our results suggest that oxidation weathering reactions may be the primary limitation in the coevolution of both secondary silicate and secondary oxide minerals. We value element depletion profiles to understand weathering, but our finding of nested weathering fronts driven by different chemical processes (e.g., oxidation to 3 m and acid dissolution to 10 m) warrants the recognition that element depletion profiles are not able to identify the full set of processes that occur in weathering profiles.

Comparative study on real-time pose estimation of vision-based unmanned underwater vehicles

Background: Navigation and localization are key to the successful execution of autonomous unmanned underwater vehicles (UUVs) in marine environmental monitoring, underwater 3D mapping, and ocean resource surveys. The estimation of the position and the orientation of autonomous UUVs are a long-standing challenging and fundamental problem. As one of the underwater sensors, camera has always been the focus of attention due to its advantages of low cost and rich content information in visibility waters, especially in the fields of visual perception of the underwater environment, target recognition and tracking. At present, the visual real-time pose estimation technology that can be used for UUVs is mainly divided into geometry-based visual positioning algorithms and deep learning-based visual positioning algorithms. Methods: In order to compare the performance of different positioning algorithms and strategies, this paper uses C++ and python, takes the ORB-SLAM3 algorithm and DF-VO algorithm as representatives to conduct a comparative experiment and analysis. Results: The geometry-based algorithm ORB-SLAM3 is less affected by illumination, performs more stably in different underwater environments, and has a shorter calculation time, but its robustness is poor in complex environments. The visual positioning algorithm DF-VO based on deep learning takes longer time to compute, and the positioning accuracy is more easily affected by illumination, especially in dark conditions. However, its robustness is better in unstructured environments such as large-scale image rotation and dynamic object interference. Conclusions: In general, the deep learning-based algorithm is more robust, but multiple deep learning networks make it need more time to compute. The geometry-based method costs less time and is more accurate in low-light and turbid underwater conditions. However, in real underwater situations, these two methods can be connected as binocular vision or methods of multi-sensor combined pose estimation.

Reduction of permanent pacemaker implantation by using the cusp overlap technique in transcatheter aortic valve replacement: a meta-analysis

BackgroundThe need for permanent pacemaker (PPM) implantation is a common complication after transcatheter aortic valve replacement (TAVR). Deep implantation position is a risk factor for PPM implantation. Thus, in the field of self-expandable (SE) transcatheter heart valves (THV) cusp overlap projection (COP) technique was implemented to reduce parallax, allowing a more precise guidance of implantation depth.AimsThis meta-analysis aims to report the outcome of patients undergoing TAVR with SE THV using COP versus conventional implantation technique (CIT).MethodsSystematical search in MEDLINE and EMBASE yielded five observational controlled studies comparing both implantation techniques for the SE Evolut prosthesis (Medtronic Intern. Ltd., CA, USA) and fulfilling the inclusion criteria for meta-analysis.ResultsTotally, 1227 patients were included, comprising 641 who underwent COP and 586 CIT TAVR. Incidence of post-procedural need for PPM implantation was significantly lower in COP group (9.8% vs 20.6%; OR = 0.43; p < 0.00001). This was accompanied by significantly higher implantation position in COP group (mean difference distance from distal end of the intraventricular portion of the THV to the non-coronary cusp (NCC): − 1.03 mm; p = 0.00001). Incidence of new-onset left bundle branch block did not differ. Regarding procedural and 30-day mortality, technical success, post-procedural aortic regurgitation, and rates of multiple device implantation, no difference between COP and CIT was found.ConclusionCOP is an effective and safe implantation technique to reduce the need for a permanent pacemaker implantation during TAVR with SE Evolut prosthesis.Graphical abstract