Application of Pore Evolution and Fracture Development Coupled Models in the Prediction of Reservoir "Sweet Spots" in Tight Sandstones

The Chang-63 reservoir in the Huaqing area has widely developed tight sandstone ＂thick sand layers, but not reservoirs characterized by rich in oil＂, and it is thus necessary to further study its oil and gas enrichment law. This study builds porosity and fracture development and evolution models in different deposition environments, through core observation, casting thin section, SEM, porosity and permeability analysis, burial history analysis, and ＂four-property-relationships＂ analysis.

Risk factors for acute kidney injury following coronary artery bypass graft surgery in a Chinese population and development of a prediction model

BACKGROUND Acute kidney injury(AKI)after coronary artery bypass graft(CABG)surgery is associated with significant morbidity and mortality.This retrospective study aimed to establish a risk score for postoperative AKI in a Chinese population.METHODS A total of 1138 patients undergoing CABG were collected from September 2018 to May 2020 and divided into a derivation and validation cohort.AKI was defined according to the Kidney Disease Improving Global Outcomes(KDIGO)criteria.Multivariable logistic regression analysis was used to determine the independent predictors of AKI,and the predictive ability of the model was determined using a receiver operating characteristic(ROC)curve.RESULTS The incidence of cardiac surgery–associated acute kidney injury(CSA-AKI)was 24.17%,and 0.53%of AKI patients required dialysis(AKI-D).Among the derivation cohort,multivariable logistic regression showed that age≥70 years,body mass index(BMI)≥25 kg/m2,estimated glomerular filtration rate(eGFR)≤60 mL/min per 1.73 m2,ejection fraction(EF)≤45%,use of statins,red blood cell transfusion,use of adrenaline,intra-aortic balloon pump(IABP)implantation,postoperative low cardiac output syndrome(LCOS)and reoperation for bleeding were independent predictors.The predictive model was scored from 0 to32 points with three risk categories.The AKI frequencies were as follows:0-8 points(15.9%),9-17 points(36.5%)and≥18 points(90.4%).The area under of the ROC curve was 0.730(95%CI:0.691-0.768)in the derivation cohort.The predictive index had good discrimination in the validation cohort,with an area under the curve of 0.735(95%CI:0.655-0.815).The model was well calibrated according to the Hosmer-Lemeshow test(P=0.372).CONCLUSION The performance of the prediction model was valid and accurate in predicting KDIGO-AKI after CABG surgery in Chinese patients,and could improve the early prognosis and clinical interventions.

Development of a risk score to guide targeted hepatitis C testing among human immunodeficiency virus patients in Cambodia

BACKGROUND The World Health Organization recommends testing all human immunodeficiency virus(HIV)patients for hepatitis C virus(HCV).In resource-constrained contexts with low-to-intermediate HCV prevalence among HIV patients,as in Cambodia,targeted testing is,in the short-term,potentially more feasible and cost-effective.AIM To develop a clinical prediction score(CPS)to risk-stratify HIV patients for HCV coinfection(HCV RNA detected),and derive a decision rule to guide prioritization of HCV testing in settings where‘testing all’is not feasible or unaffordable in the short term.METHODS We used data of a cross-sectional HCV diagnostic study in the HIV cohort of Sihanouk Hospital Center of Hope in Phnom Penh.Key populations were very rare in this cohort.Score development relied on the Spiegelhalter and Knill-Jones method.Predictors with an adjusted likelihood ratio≥1.5 or≤0.67 were retained,transformed to natural logarithms,and rounded to integers as score items.CPS performance was evaluated by the area-under-the-ROC curve(AUROC)with 95% confidence intervals(CI),and diagnostic accuracy at the different cut-offs.For the decision rule,HCV coinfection probability≥1% was agreed as test-threshold.RESULTS Among the 3045 enrolled HIV patients,106 had an HCV coinfection.Of the 11 candidate predictors(from history-taking,laboratory testing),seven had an adjusted likelihood ratio≥1.5 or≤0.67:≥50 years(+1 point),diabetes mellitus(+1),partner/household member with liver disease(+1),generalized pruritus(+1),platelets<200×10^(9)/L(+1),aspartate transaminase(AST)<30 IU/L(-1),AST-to-platelet ratio index(APRI)≥0.45(+1),and APRI<0.45(-1).The AUROC was 0.84(95%CI:0.80-0.89),indicating good discrimination of HCV/HIV coinfection and HIV mono-infection.The CPS result≥0 best fits the test-threshold(negative predictive value:99.2%,95%CI:98.8-99.6).Applying this threshold,30%(n=926)would be tested.Sixteen coinfections(15%)would have been missed,none with advanced fibrosis.CONCLUSION The CPS performed well in the derivation cohort,and bears potential for other contexts of low-to-intermediate prevalence and little onward risk of transmission(i.e.cohorts without major risk factors as injecting drug use,men having sex with men),and where available resources do not allow to test all HIV patients as recommended by WHO.However,the score requires external validation in other patient cohorts before any wider use can be considered.

Trend Prediction Method Based on the Largest Lyapunov Exponent for Large Rotating Machine Equipments

In order to predict electromechanical equipments＇ nonlinear and non-stationary condition effectively, max Lyapunov exponent is introduced to the fault trend prediction of large rotating mechanical equipments based on chaos theory. The predict method of chaos time series and two methods of proposing f and F are dis- cussed. The arithmetic of max prediction time of chaos time series is provided. Aiming at the key part of large rotating mechanical equipments-bearing, used this prediction method the simulation experiment is carried out. The result shows that this method has excellent performance for condition trend prediction.

Progress on the Key Technology Development in Application of Ensemble Prediction Products Associated with TIGGE

This project is supported by the 2007 R ＆ D Special Fund for Public Welfare by Ministry of Science and Technology and Ministry of Finance.Research tasks in this project are proposed based on the implementation plan of the＂THORPEX（The Observing System Research and Predictability Experiment） Interactive Grand Global Ensemble（TIGGE）＂,a sub-project of the THORPEX international program.

Development and validation of a radiomics nomogram for preoperative prediction of lymph node metastasis in colorectal cancer

With the support by the National Natural Science Foundation of China,the research team jointly led by Porf.Liu Zaiyi(刘再毅)at Guangdong General Hospital and Prof.Tian Jie(田捷)at the Key Laboratory of Molecular Imaging,Chinese Academy of Sciences,developed a CT-based radiomics prediction model to preoperatively predict the lymph node metastasis in colorectal cancer(CRC),which was published

Has the Prediction of the South China Sea Summer Monsoon Improved Since the Late 1970s?

Based on the evaluation of state-of-the-art coupled ocean-atmosphere general circulation models （CGCMs） from the ENSEMBLES （Ensemble-based Predictions of Climate Changes and Their Impacts） and DEME- TER （Development of a European Multimodel Ensemble System for Seasonal to Interannual Prediction） projects, it is found that the prediction of the South China Sea summer monsoon （SCSSM） has improved since the late 1970s. These CGCMs show better skills in prediction of the atmospheric circulation and precipitation within the SCSSM domain during 1979-2005 than that during 1960-1978. Possible reasons for this improvement are investigated. First, the relationship between the SSTs over the tropical Pacific, North Pacific and tropical Indian Ocean, and SCSSM has intensified since the late 1970s. Meanwhile, the SCSSM-related SSTs, with their larger amplitude of interannual variability, have been better predicted. Moreover, the larger amplitude of the interannual variability of the SCSSM and improved initializations for CGCMs after the late 1970s contribute to the better prediction of the SCSSM. In addition, considering that the CGCMs have certain limitations in SCSSM rainfall prediction, we applied the year-to-year increment approach to these CGCMs from the DEMETER and ENSEMBLES projects to improve the prediction of SCSSM rainfall before and after the late 1970s.

THE NUMERICAL PREDICTION OF DEVELOPING TURBULENT FLOW IN 3-D RECTANGULAR DUCTS

Comparisons are made between experimental data and numerical predictions based on the k-e turbulent model of low Reynolds number applicable to developing turbulent flow in rectangular ducts of arbitrary aspect ratio.The numerical procedure utilizes the separated-layers finite-analytical method.The merits of the k-e turbulent model of low Reynolds number and the computation procedure are assessed by means of comparison with results,referred to that of the length-scale model and the full-Reynolds-stress model used in recent years.