Characterization of Malalignment between Atrial and Ventricular Septa in Overriding/Straddling Tricuspid and Mitral Valves

Objective:Overriding/straddling of an atrioventricular valve is a consequence of atrial-ventricular septal malalignment.We sought to characterize the malalignment by analogizing it to a flap-door and using structured approach.Methods:The echocardiograms and magnetic resonance images of 35 patients with overriding/straddling tricuspid or mitral valve were evaluated to assess the following modifiers;the malaligned part of the septum,the reference structure,and the mechanism,direction and severity of malalignment.Results:The pathology included classic overriding tricuspid valve in 15,classic overriding mitral valve in 12,and overriding tricuspid valve with left juxtaposition of atrial appendages in 8.In classic overriding tricuspid valve,the ventricular septum was hinged to the anterior interventricular groove and its insertion to the posterior interventricular groove was displaced toward the right ventricle.The VSD primarily involved the inlet but also extended toward the anterior interventricular groove.In classic overriding mitral valve,the ventricular septum was hinged to the posterior interventricular groove and crux cordis.Its insertion to the anterior interventricular groove was displaced toward the left ventricle.The VSD primarily involved the anterior part but also extended toward the inlet.Overriding tricuspid valve with left juxtaposition of atrial appendages had a mild degree of malalignment with displacement/rotation of the atrioventricular junction.Evenly spaced short-axis images were most helpful in characterizing the pathology.Conclusions:Overriding/straddling atrioventricular valves can be easily understood by analogizing the atrial-ventricular septal malalignment to a flap-door and describing the pathology in a structured manner.Contrary to what has previously been known,the VSD is not limited to the inlet or outlet part of the ventricular septum.

Dynamic Performance of Straddle Monorail Curved Girder Bridge

In this work,a monorail vehicle-bridge coupling(VBC)model capable of accurately considering curve alignment and superelevation is established based on curvilinear moving coordinate system,to study the VBC vibration of straddlemonorail curved girder bridge and the relevant factors influencing VBC.While taking Chongqing Jiao Xin line as an example,the VBC program is compiled using Fortran,where the reliability of algorithm and program is verified by the results of Chongqing monorail test.Moreover,the effects of curve radius,vehicle speed,and track irregularity on the corresponding vehicle and bridge vibrations are compared and analyzed.It is observed that the test results of lateral vibration acceleration(LVA)and vertical vibration acceleration(VVA)of track beam,and LVA of vehicle,are consistent with the simulation results.Owing to the track irregularity,vibration of track beam and vehicle increases significantly.Besides,an increase in vehicle speed gradually increases the vibration of track beam and vehicle.For the curve radius(R)≤200 m,lateral and vertical vibrations of the track beam and vehicle decrease significantly with an increasing curve radius.Alternatively,when 200 m<R<600 m,the lateral vibration of the track beamand vehicle decreases slowly with an increasing curve radius,while the relevant vertical vibration remains stable.Similarly,when R≥600 m,the lateral and vertical vibrations of the track beam and vehicle tend to be stable.Accordingly,the results presented here can provide a strong reference for the design,construction,and safety assessment of existing bridges.

A Hybrid Importance Sampling Algorithm for Estimating VaR under the Jump Diffusion Model

Value at Risk (VaR) is an important tool for estimating the risk of a financial portfolio under significant loss. Although Monte Carlo simulation is a powerful tool for estimating VaR, it is quite inefficient since the event of significant loss is usually rare. Previous studies suggest that the performance of the Monte Carlo simulation can be improved by impor-tance sampling if the market returns follow the normality or the distributions. The first contribution of our paper is to extend the importance sampling method for dealing with jump-diffusion market returns, which can more precisely model the phenomenon of high peaks, heavy tails, and jumps of market returns mentioned in numerous empirical study papers. This paper also points out that for portfolios of which the huge loss is triggered by significantly distinct events, naively applying importance sampling method can result in poor performance. The second contribution of our paper is to develop the hybrid importance sampling method for the aforementioned problem. Our method decomposes a Monte Carlo simulation into sub simulations, and each sub simulation focuses only on one huge loss event. Thus the perform-ance for each sub simulation is improved by importance sampling method, and overall performance is optimized by determining the allotment of samples to each sub simulation by Lagrange’s multiplier. Numerical experiments are given to verify the superiority of our method.

On the Uniform and Simultaneous Approximations of Functions

We consider the relation between the simultaneous approximation of two functions and the uniform approximation to one of these functions. In particular, F1 and F2 are continuous functions on a closed interval [a,b], S is an n-dimensional Chebyshev subspace of C [a,b] and s1* & s2* are the best uniform approximations to F1 and F2 from S respectively. The characterization of the best approximation solution is used to show that, under some restrictions on the point set of alternations of F1−s1* and F2−s2*, s1* or s2* is also a best A(1) simultaneous approximation to F1 and F2 from S with F1≥F2 and n=2.

A survey of emergency blunt urethral injury management in China:Reality versus guidelines

Background:Although urethral trauma may lead to serious consequences if mismanaged,treatment concepts are inconsistent.We designed a survey to investigate the current diagnosis and management of emergency blunt urethral trauma to aid future dissemination of relevant concepts.Methods:A 15‐item anonymous questionnaire was distributed via an online platform.It addressed items such as the cognition of how to diagnose of urethral trauma,optimal emergency management of a urethral trauma patient,and attitude towards early realignment for pelvic fracture urethral injuries.Results:Of 538 respondents,94.2%and 84.9%had received patients with straddle trauma urethral injuries or pelvic fracture urethral injuries,respectively,within the past year.In the emergency room,attempted urethral catheterization was the most selected examination method by respondents for diagnosis of both straddle injury(500/538)and pelvic fracture urethral injury(469/538).For patients with straddle injury,41.3%of respondents performed endoscopic realignment and 31.6%preferred suprapubic cystostomy.For hemodynamically stable patients with PFUI,42.2%of respondents preferred suprapubic cystostomy and 34.9%preferred endoscopic realignment.Most respondents felt favorably toward early realignment for pelvic fracture urethral injuries.After realignment,61.3%,24.5%,and 13.8%of respondents performed catheterization for 4,8,and 12 weeks,respectively.Further,54.6%of respondents believed catheter traction should be applied after realignment.Conclusion:Although the number of yearly emergency urethral trauma cases was small,the opinions and practices of most urologists were consistent with guidelines.However,the significance of retrograde urethrography was not fully understood,and some respondents had incorrect views on catheter traction after realignment.