Ventricular fibrillation in congenitally corrected transposition of great arteries treated with pacing: a case report

Background Congenitally corrected transposition of the great arteries (CCTGA) is a rare form of congenital heart disease which may present with sudden death from malignant arrhythmias including complete heart block and ventricular tachyarrhythmias as late complications. Only few cases about ventricular tachyarrhythmias, usually in those with markedly depressed systemic ventricular function, have been reported. Case summary A 26-year-old woman with a known history of CCTGA presented to the emergency department with palpitations and breathlessness for 3–4 weeks and worsening symptoms for 8 h. She had a history of ventricular septal defect repair 14 years ago. Her initial presentation electrocardiogram demonstrated high degree atrioventricular block with a ventricular rate of 44 b.p.m. She had two episodes of complete syncope during this hospitalization, both required external defibrillation due to documented bradycardia-dependent ventricular fibrillations. Her two-dimensional echocardiography study confirmed the diagnosis of CCTGA with preserved systolic ventricular function. She underwent urgent temporal pacing wire placement with a paced ventricular rate at 90 b.p.m. Having thoroughly reviewed the arrhythmia events and discussed with the patient about the option of defibrillator vs. pacemaker therapy a decision was made upon her request for dual-chamber pacemaker implantation. She was discharged home uneventfully 3 days after hospital presentation and has been physically active at 3-, 6-, and 9-month follow-ups. Discussion Our case illustrates the individualized clinical decision making in choosing device therapy for a rare congenital heart disease presented with malignant arrhythmia. Careful history taking, open communication, and closely planned long-term follow-up will be essential in caring for such patients

Dual Attention Multiscale Network for Vessel Segmentation in Fundus Photography

Automatic vessel structure segmentation is essential for an automatic disease diagnosis system. The task is challenging due to vessels’ different shapes and sizes across populations. This paper proposes a multiscale network with dual attention to segment various retinal blood vessels. The network injects a spatial attention module and channel attention module on a feature map, whose size is one-eighth of the input size. The network also uses multiscale input to receive multi-level information, and the network uses the multiscale output to gain more supervision. The proposed method is tested on two publicly available datasets: DRIVE and CHASEDB1. The accuracy, AUC, sensitivity, and specificity on the DRIVE dataset are 0.9615, 0.9866, 0.7709, and 0.9847, respectively. On the CHASEDB1 dataset, the metrics are 0.9800, 0.9892, 0.8215, and 0.9877, respectively. The ablative study further shows effectiveness for each part of the network. Multiscale and dual attention mechanism both improve performance. The proposed architecture is simple and effective. The inference time is 12 ms on a GPU and has potential for real-world applications. The code will be made publicly available

Identification of Distributed Dynamic Characteristics of Journal Bearing with Large Aspect Ratio under Shaft Bending

The classical theory of centralized dynamic characteristics with eight coefficients is adopted for traditional journal bearings. However, under cantilevered load, distributed dynamic characteristics along the axial direction will be generated for the journal bearing with a large aspect ratio (L/D). A double-section loading method simulating shaft bending and excitation was developed, a dynamic characteristic test-rig of a large-aspect-ratio bearing was set-up, the novel four-time vertical excitation method and eight-time cross excitation method were put forward, and the equations of 16 dynamic characteristic coefficients of the bearing were deduced. The dynamic characteristic test was carried out. The results showed that the four-time vertical excitation method had a small response amplitude in the horizontal direction, and was vulnerable to interference by the vibration of the test-rig. The eight-time cross excitation method had a higher SNR with more accurate identification results. When the cantilevered load was not applied, the dynamic characteristic coefficients were evenly distributed along the axial direction, the stiffness coefficients fluctuated slightly as the rotation rate increased, while the main damping coefficients decreased significantly. Shaft bending resulted in a significant increase in local dynamic characteristic coefficients, in which the relative increase in the stiffness coefficients was greater than that of the damping coefficients. Increasing the rotational speed can weaken the effect of shaft bending, and key factors that cause the axially nonuniform distribution of dynamic characteristic coefficients of the bearing are shaft bending and large aspect ratio under low speed and cantilevered load

Identification of Distributed Dynamic Characteristics of Journal Bearing with Large Aspect Ratio under Shaft Bending

The classical theory of centralized dynamic characteristics with eight coefficients is adopted for traditional journal bearings. However, under cantilevered load, distributed dynamic characteristics along the axial direction will be generated for the journal bearing with a large aspect ratio (L/D). A double-section loading method simulating shaft bending and excitation was developed, a dynamic characteristic test-rig of a large-aspect-ratio bearing was set-up, the novel four-time vertical excitation method and eight-time cross excitation method were put forward, and the equations of 16 dynamic characteristic coefficients of the bearing were deduced. The dynamic characteristic test was carried out. The results showed that the four-time vertical excitation method had a small response amplitude in the horizontal direction, and was vulnerable to interference by the vibration of the test-rig. The eight-time cross excitation method had a higher SNR with more accurate identification results. When the cantilevered load was not applied, the dynamic characteristic coefficients were evenly distributed along the axial direction, the stiffness coefficients fluctuated slightly as the rotation rate increased, while the main damping coefficients decreased significantly. Shaft bending resulted in a significant increase in local dynamic characteristic coefficients, in which the relative increase in the stiffness coefficients was greater than that of the damping coefficients. Increasing the rotational speed can weaken the effect of shaft bending, and key factors that cause the axially nonuniform distribution of dynamic characteristic coefficients of the bearing are shaft bending and large aspect ratio under low speed and cantilevered load

The advancement of cluster based FPGA place & route technic

As one of the core components of electronic hardware systems, Field Programmable Logic Array (FPGA) device design technology continues to advance under the guidance of electronic information technology policies, and has made information technology applications. huge contribution. However, with the advancement of chip technology and the continuous upgrading of information technology, the functions that FPGAs need to perform are more and more complicated. How to efficiently perform layout design and make full use of chip resources has become an important technology to be solved and optimized in FPGA design. The FPGA itself is not limited to a specific function. It contains internal functions such as memory, protocol module, clock module, high-speed interface module and digital signal processing. It can be programmed through logic modules such as programmable logic unit modules and interconnects. Blank FPGA devices are designed to be high performance system applications with complex functions. The layout and routing technology based on cluster logic unit blocks can combine the above resources to give full play to its performance advantages, and its importance is self-evident. Based on the traditional FPGA implementation, this paper analyzes several advantages based on cluster logic block layout and routing technology, and generalizes the design method and flow based on cluster logic block layout and routing technology

Observations of boundary layer wind and turbulence of a landfalling tropical cyclone

This study investigates the atmospheric boundary layer structure based on multiple-level tower observations with a height of 350 m during the landfall of Super Typhoon Mangkhut (2018). Results show a layer of log wind profile outside of the radius of maximum wind speed with a height of 100 m or larger. The log layer height increases with the wind speed. The height of the constant flux layer reaches ~ 300 m for 10-m wind speeds less than 13 m s−1while this height decreases with the wind speed. Momentum fluxes and turbulent kinetic energy increase with the wind speed at all vertical levels. The drag coefficient and surface roughness length estimated at the tower location have values of 7.3 × 10–3and 0.09 m, respectively, which are independent of wind speed. The estimated vertical eddy diffusivity and mixing length increase with height up to ~ 160 m and then slowly decrease with height. The vertical eddy diffusivity increases with the wind speed while the vertical mixing length has no dependence on the wind speed. Comparing our results with previous work indicates that the vertical eddy diffusivity is larger over land than over ocean at a given wind speed range

A Cellulose-Type Carrier for Intimate Coupling Photocatalysis and Biodegradation

Intimate coupling photocatalysis and biodegradation treatment technology is an emerging technology in the treatment of refractory organic matter, and the carrier plays an important role in this technology. In this paper, sugarcane cellulose was used as the basic skeleton, absorbent cotton was used as a reinforcing agent, anhydrous sodium sulfate was used as a pore-forming agent to prepare a cellulose porous support with good photocatalytic performance, and nano-TiO2 was loaded onto it by a low-temperature bonding method. The results showed that the optimal preparation conditions of cellulose carriers were: cellulose mass fraction 1.0%; absorbent cotton 0.6 g; and Na2SO4 60 g. The SEM, EDS and XPS characterization further indicated that the nano-TiO2 was uniformly loaded onto the cellulose support. The degradation experiments of Rhodamine B showed that the nano-TiO2-loaded composite supports had good photocatalytic performance. The degradation rate of 1,2,4-trichlorobenzene was more than 92% after 6 cycles, and the experiment of adhering a large number of microorganisms on the carriers before and after the reaction showed that the cellulose-based carriers obtained the required photocatalytic performance and stability, which is a good cellulose porous carrier

Image2_Experiment with the dynamical–statistical–analog ensemble forecast model for landfalling typhoon gale over South China.JPEG

In this study, an experiment based on the Dynamical-Statistical-Analog Ensemble Forecast model for Landfalling Typhoon Gale (DSAEF_LTG model) was conducted to predict tropical cyclone (TC)-induced potential maximum gales in South China for the first time. A total of 21 TCs with maximum gales greater than or equal to 17.2 m/s (at least one station) during 2011–2018 were selected for this experiment. Among them, 16 TCs in 2011–2015 were selected as the training samples aimed at identifying the best forecast scheme, while 5 TCs in 2016–2018 were selected as the independent samples to verify the best forecast scheme. Finally, the forecast results were compared with four numerical weather prediction (NWP) models (i.e., CMA, ECMWF, JMA and NCEP) based on four forecasting skill scores (Threat Score, False Alarm Ratio, Missing Ratio and Bias Score) at thresholds above Beaufort Scale 7 and 10, and two more indicators (Mean Absolute Error and pearson correlation coefficient). The results revealed encouraging forecasting ability in South China for the DSAEF_LTG model. In general, the DSAEF_LTG model showed higher forecasting skill than the NWP models above the critical thresholds. While the DSAEF_LTG model was prone to false alarms, the NWP models were prone to missing alarms, especially for an intense scale (≥Beaufort Scale 10). In addition, the DSAEF_LTG model also performed best with the smallest forecasting error. Furthermore, the DSAEF_LTG model had distinct advantages in predicting target TCs with typical tracks and widespread gales, both in terms of the wind field pattern and the magnitude of central wind speeds. However, for sideswiping TCs with small-scale gales, the DSAEF_LTG model tended to over-predict and held no advantage over the NWP models, which could perhaps be improved by introducing more reasonable ensemble forecast schemes in further research.</p