Risk factors related to acute renal failure after cardiac surgery for congenital heart disease in low body weight infants

Background Acute renal failure （ARF） is a common complication and a very important cause of postoperative death in children with congenital heart disease. Large cohort investigation of the morbidity and related risk factors for ARF in very young and low-body-weight children in China is still absent. Methods Data of 518 infants after cardiac surgery were analyzed retrospectively. The correlation between multivariate risk factors and ARF after cardiac surgery was analyzed by logistic regression. Results The incidence of postoperative ARF within 30 days was 6.9% （n = 36）. High RACHS-1 Score, long duration of CPB, rethoracotomy exploration and postoperative low cardiac output were independent risk factors of ARF. There were statistical significances in intensive care unit staying [（21.73 ± 7.28） days vs （7.41 ± 3.76） days], P 0. 001] and mortality （27.8% vs 7.5%, P 0. 001） between the patients with or without ARF. Conclusions Acute renal failure is a key negative factor for the survivors after cardiac surgery for congenital heart disease in very young patients with low body weight. High RACHS-1 Score, long duration of CPB, rethoracotomy exploration and postoperative low cardiac output are independent risk factors for development of ARF.

Correlation between Low Tube Voltage in Dual Source CT Coronary Artery Imaging with Image Quality and Radiation Dose

The influence of low tube voltage in dual source CT（DSCT） coronary artery imaging on image quality and radiation dose and its application value in clinical practice were investigated. Totally, 300 cases of chest pain with low body mass index（BMI 〈18.5 kg/m2） subjected to DSCT coronary artery imaging were prospectively enrolled. The heart rate in all patients were greater than 65/min. The retrospective ECG gated scanning mode and simple random sampling method were used to assign the patients into groups A, B and C（n=100 each）. The patients in groups A, B and C experienced 120-, 100-, and 80-kV tube voltage imaging respectively, and the image quality was evaluated. The CT volume dose index（CTDIvol） and dose length product（DLP） were recorded, and the effective dose（ED） was calculated in each group. The image quality scores and radiation doses in groups were compared, and the influence of tube voltage on image quality and radiation dose was analyzed. The results showed that the excellent rate of image quality in groups A, B and C was 95.69%, 94.72% and 96.33% respectively with the difference being not statistically significant among the three groups（P〉0.05）. The CTDIvol values in groups A, B and C were 51.35±12.21, 21.28±7.13 and 6.34±3.34 mGy, respectively, with the difference being statistically significant（P〈0.05）. The ED values in groups A, B and C were 9.27±1.63, 4.56±2.29 and 2.29±1.69 mSv, respectively, with the difference being statistically significant（P〈0.05）. It was suggested that for the patients with low BMI, the application of DSCT coronary artery imaging with low tube voltage can obtain satisfactory image quality, and simultaneously, significantly reduce the radiation dose.

2D numerical study on the effect of conductor between the transmitter and survey area in CSEM exploration

In CSEM exploration, the receivers are generally located about three to five times the skin depth from the transmitter. In this paper, we study the effect of a conductor between the transmitter and the survey area on the target conductor response using forward modeling and inversion. The 2D forward finite element calculations show that the conductor mainly affects the response at middle and low frequencies. The lower the resistivity and the larger the conductor, the larger the effect and the effect increases with decreasing frequency. The inversion results indicate that the calculated position of the target body can move towards the source, leading to an incorrect interpretation without considering the conductor. In order to reduce the effect of a conductor between the source and the survey area, CSEM acquisition should be conducted in three dimensions using multiple sources and 3D inversion should be used during interpretation.

Deep electrical anomaly in the M7.5 Qiongzhou earthquake region and its relation with future seismicity

From the magnetotelluric detection in the epicentral region and the adjacent areas of the 1605 M7.5 Qiongzhou earthquake, we have discovered there is a low resistive body in the deep crust of the epicentral region. The low resistive body extends straightly from the depth of about 13 km to the upper mantle, which is supposed as an uprising mantle pole. We therefore consider it is just the existing mantle pole and its upwelling thermal material that result in the faulting and stick-slipping activities of the upper crust, which is an important factor for the M7.5 Qiongzhou great earthquake occurrence. The postseismic faulting activity is characterized by creep, which shows that the risk is greatly decreased for the occurrence of a great earthquake with similar intensity in the future.

LOW FREQUENCY WAVE FORCFES ON TWO DIMENSIONAL FLOATING BODIES

Simulating incident group wave with narrow spectrum by nonlinear slowly modulated Stoking wave train and using Multiple Scales Method.problem of the second-order low frequency diffraction of group waves on a two-di mensionai floating body has been studied.The first-order and second-order low frequency diffraction potentials are derived,which lead to the second-order and third-order low frequency forces respectively.It is shown thai the sec- ond-order low frequency force generated by first-order low frequency diffraction potentials is verticcal to undis- turbed free surface,and is directly proportional to square of envelope amplitude of incident wave and to waterline width of floating body.The horizontal low frequency forces are caused by the second-order low frequency diffrac- tion potential.To determine it only two linear boundary value problems are necessary to be solved.