Study on Volume Variation and Stability of Riverbed in the Yangtze Estuary

In recent years,regional floods and typhoons have occurred in the Yangtze Estuary.Changing dynamic conditions and dramatic reduction of sediment discharge in the basin are affecting the dynamic equilibrium pattern of the Yangtze Estuary.Based on the field measurement data and theoretical derivation,this paper analyzed the changing process of runoff-sediment discharge into the sea after the operation of the Three Gorges Project(TGP),and the tidal dynamics and sediment variation characteristics of the Yangtze Estuary.The erosion of South Branch mainly occurs in the channel below-10 m contour,and the riverbed volume below contours 0 m and-10 m has a good correlation with the sediment discharge of Datong Station in the previous year.On this basis,the ratio of the horizontal distance from the starting point to the section centroid below the average water level(B_c)and the water depth at the section centroid(H_c)was proposed to describe the change of the section shape.The relationships between the water-diverting ratio,the sediment-diverting ratio and the water-diverting angle,the conditions of runoff and sediment discharge from the upper reach and the characteristics of the riverway section were established,and the theoretical calculation equations of the water-diverting ratio,the sediment-diverting ratio and the diverting angle of each bifurcation were also established.

Robust optimization for volume variation in timber processing

Volume variation is an uncertainty element which affects timber processing. We studied the volume variation of logs caused by quality defects in traditional timber processing and set up an optimization approach,using a robust optimization method. We used total number of acceptable boards produced to study the relationship between board thickness and raw material logs, using a heuristic search algorithm to control the variation of board volume to improve the output of boards, reduce the quantity of by-products, and lower production costs. The robust optimization method can effectively control the impact of volume variations in timber processing, reduce cutting waste as far as possible using incremental processing and increase profits, maximize the utilization ratio of timber, prevent waste in processing, cultivate the productive type of tree species and save forest resources.

Responsiveness of stroke volume variation and central venous pressure during acute normovolemic and hypervolemic hemodilution

Background Stroke volume variation （SW） is a robust indicator of fluid responsiveness during volume change. We compared the sensibility of SW by Vigileo/Flotrac to central venous pressure （CVP） when volume changes in patients undergoing intraoperative acute normovolemic hemodilution （ANH） and acute hypervolemic hemodilution （AHH）. Methods Forty patients were randomly divided into an ANH group （n=20） and an AHH group （n=20）. All patients received general anesthesia and were mechanically ventilated. Data were collected from 7 different time-points in the ANH group： baseline, after withdrawal of 5%, 10%, and 15% of the estimated blood volume （EBV） and after replacement with an equal volume of 6% hydroxyethyl starch 130/0.4 （HES） in 5% EBV increments to baseline. There were four time points in the AHH group： baseline, after 5%, 10%, and 15% expansion of the EBV with 6% HES. At each time-point, CVP, SW and other hemodynamic parameters measurements were obtained. Results After removal of 10% and 15% EBV, SVV significantly increased from 10.9±3.0 to 14.1±3.4 and 10.9±3.0 to16.0±3.3 （P 〈0.01）, and returned to a final value of 10.6±3.4 after volume replacement. The CVP value was unchanged after removal and replacement of 15% of the EBV. There were no significant changes in SW after 5%, 10% whereas there was a significant reduction after 15% （8.2±1.7） expansion of the EBV compared with baseline （9.9±1.8） （P=0.033）. However, there was a significant increase in CVP after10% （10.3±2.4）, 15% （11.3±2.2） expansion of the EBV compared with baseline （8.2±2.7） （P 〈0.01）. Conclusion SW is a more sensitive parameter for volume than CVP during hypovolemia, on the contrary CVP is more sensitive than SW during hypervolemia.

Assessment of liver volume variation to evaluate liver function

In order to assess the value of liver volumetry in cirrhosis and acute liver failure(ALF)patients,we explored the correlation between hepatic volume and severity of the hepatic diseases.The clinical data of 48 cirrhosis patients with 60 normal controls and 39 ALF patients were collected.Computed tomography-derived liver volume(CTLV)and body surface area(BSA)of normal controls were calculated to get a regression formula for standard liver volume(SLV)and BSA.Then CTLV and SLV of all patients were calculated and grouped by Child-Turcotte-Pugh classification for cirrhosis patients and assigned according to prognosis of ALF patients for further comparison.It turned out that the mean liver volume of the control group was 1058±337 cm^(3).SLV was correlated with BSA according to the regression formula.The hepatic volume of cirrhosis patients in Child A,B level was not reduced,but in Child C level it was significantly reduced with the lowest liver volume index(CTLV/SLV).Likewise,in the death group of ALF patients,the volume index was significantly lower than that of the survival group.Based on volumetric study,we proposed an ROC(receiver operating characteristic)analysis to predict the prognosis of ALF patients that CTLV/SLV<83.9% indicates a poor prognosis.In conclusion,the CTLV/SLV ratio,which reflects liver volume variations,correlates well with the liver function and progression of cirrhosis and ALF.It is also a very useful marker for predicting the prognosis of ALF.

Experimental study of the shrinkage behavior of cemented paste backfill

Cemented paste backfill(CPB)is largely used in underground mine stopes worldwide.When a CPB is placed in a stope,an important task is to estimate the settlement associated with the shrinkage and selfweight consolidation of the CPB.This is closely related to the volume management to ensure the stability of barricades and tight contacts between the backfill and stope roof.Over the years,shrinkage studies were mostly performed on fine-grained soils(silts and clays),with only a few publications on the shrinkage behavior of uncemented tailings.No study has been published on the shrinkage behavior of CPB.To fill this gap,a series of shrinkage tests has been conducted on CPB with different cement contents,including zero cement content(uncemented paste backfill,uCPB).The results show that the shrinkage response of CPB is very different from that of uCPB.At a given initial water content,CPB exhibits a shorter normal shrinkage stage than uCPB.The unsaturation onset water content and void ratio,shrinkage limit and final void ratio of CPB are generally higher than those of uCPB.At a given cement content,the shrinkage behaviors of CPB and uCPB are significantly influenced by the initial water content.

Goal-directed fluid therapy in gastrointestinal cancer surgery:A prospective randomized study

Objective:To investigate the effects of perioperative goal-directed fluid therapy(GDFT)on intraoperative fluid balance,postoperative morbidity,and mortality.Methods:This is a prospective randomized study,and 90 patients who underwent elective open gastrointestinal cancer surgery between April 2017 and May 2018 were included.Patients were randomized into 2 groups that received liberal fluid therapy(the LFT group,n=45)and goal-directed fluid therapy(the GDFT group,n=45).Patients’Colorectal Physiologic and Operative Severity Score for the enUmeration of Mortality and Morbidity(CR-POSSUM)physiological score,Charlson Comorbidity Index(CCI),perioperative vasopressor and inotrope use,postoperative AKIN classification,postoperative intensive care unit(ICU)hospitalization,hospital stay,and 30-day mortality were recorded.Results:The volume of crystalloid used perioperatively and the total volume of fluid were significantly lower in the GDFT group compared to the LFT group(P<0.05).CR-POSSUM physiological score and CCI were significantly higher in the GDFT group(P<0.05).Although perioperative vasopressor and inotrope use was significantly higher in the GDFT group(P<0.05),postoperative acute kidney injury development was not affected.Postoperative mortality was determined to be similar in both groups(P>0.05).Conclusion:Although GDFT was demonstrated to be a good alternative method to LFT in open gastrointestinal cancer surgery,and it can prevent perioperative fluid overload,and the postoperative results are comparable in the two groups.

Effect of two volume responsiveness evaluation methods on fluid resuscitation and prognosis in septic shock patients

Background Few studies have reported the effect of different volume responsiveness evaluation methods on volume therapy results and prognosis.This study was carried out to investigate the effect of two volume responsiveness evaluation methods,stroke volume variation （SW） and stroke volume changes before and after passive leg raising （PLR-ASV）,on fluid resuscitation and prognosis in septic shock patients.Methods Septic shock patients admitted to the Department of Critical Care Medicine of Zhejiang Hospital,China,from March 2011 to March 2013,who were under controlled ventilation and without arrhythmia,were studied.Patients were randomly assigned to the SVV group or the PLR-ASV group.The SVV group used the Pulse Indication Continuous Cardiac Output monitoring of SW,and responsiveness was defined as SW-＞12％.The PLR-ASV group used ASV before and after PLR as the indicator,and responsiveness was defined as ASV ＞15％.Six hours after fluid resuscitation,changes in tissue perfusion indicators （lactate,lactate clearance rate,central venous oxygen saturation （SCVO2）,base excess （BE））,organ function indicators （white blood cell count,neutrophil percentage,platelet count,total protein,albumin,alanine aminotransferase,total and direct bilirubin,blood urea nitrogen,serum creatinine,serum creatine kinase,oxygenation index）,fluid balance （6-and 24-hour fluid input） and the use of cardiotonic drugs （dobutamine）,prognostic indicators （the time and rate of achieving early goal-directed therapy （EGDT） standards,duration of mechanical ventilation and intensive care unit stay,and 28-day mortality） were observed.Results Six hours after fluid resuscitation,there were no significant differences in temperature,heart rate,blood pressure,SpO2,organ function indicators,or tissue perfusion indicators between the two groups （P ＞0.06）.The 6-and 24-hour fluid input was slightly less in the SW group than in the PLR-ASV group,but the difference was not statistically significant （P ＞0.05）.The SW group used significantly more dobutamine than the PLR-ASV group （33.3％ vs.10.7％,P =0.039）.There were no significant differences in the time （（4.8±1.4） h vs.（4.3±1.3） h,P=0.142） and rate of achieving EGDT standards （90.0％ vs.92.9％,P =0.698）,or in the length of mechanical ventilation and ICU stay.The 28-day mortality in the SW group （16.7％ （5/30）） was slightly higher than the PLR-ASV group （14.3％ （4/28））,but the difference was not statistically significant （P =0.788）.Conclusions In septic shock patients under controlled ventilation and without arrhythmia,using SW or PLR-ASV methods to evaluate volume responsiveness has a similar effect on volume therapy results and prognosis.The evaluation and dynamic monitoring of volume responsiveness is more important for fluid resuscitation than the evaluation methods themselves.Choosing different methods to evaluate volume responsiveness has no significant influence on the effect of volume therapy and prognosis.

On the Variation of a Metric and Its Application

Some of the variation formulas of a metric were derived in the literatures by using the local coordinates system, In this paper, We give the first and the second variation formulas of the Riemannian curvature tensor, Ricci curvature tensor and scalar curvature of a metric by using the moving frame method. We establish a relation between the variation of the volume of a metric and that of a submanifold. We find that the latter is a consequence of the former. Finally we give an application of these formulas to the variations of heat invariants. We prove that a conformally flat metric g is a critical point of the third heat invariant functional for a compact 4-dimensional manifold M, then （M, g） is either scalar flat or a space form.

Mandatory criteria for the application of variability-based parameters of fluid responsiveness: a prospective study in different groups of ICU patients

Background and objective： Stroke volume variation（SVV） has high sensitivity and specificity in predicting fluid responsiveness. However, sinus rhythm（SR） and controlled mechanical ventilation（CV） are mandatory for their application. Several studies suggest a limited applicability of SVV in intensive care unit（ICU） patients. We hypothesized that the applicability of SVV might be different over time and within certain subgroups of ICU patients. Therefore, we analysed the prevalence of SR and CV in ICU patients during the first 24 h of Pi CCO-monitoring（primary endpoint） and during the total ICU stay. We also investigated the applicability of SVV in the subgroups of patients with sepsis, cirrhosis, and acute pancreatitis. Methods： The prevalence of SR and CV was documented immediately before 1241 thermodilution measurements in 88 patients. Results： In all measurements, SVV was applicable in about 24%. However, the applicability of SVV was time-dependent： the prevalence of both SR and CV was higher during the first 24 h compared to measurements thereafter（36.1% vs. 21.9%; P0.001）. Within different subgroups, the applicability during the first 24 h of monitoring ranged between 0% in acute pancreatitis, 25.5% in liver failure, and 48.9% in patients without pancreatitis, liver failure, pneumonia or sepsis. Conclusions： The applicability of SVV in a predominantly medical ICU is only about 25%–35%. The prevalence of both mandatory criteria decreases over time during the ICU stay. Furthermore, the applicability is particularly low in patients with acute pancreatitis and liver failure.