Association of nonmalignant portal vein thrombosis and clinical outcomes in patients with cirrhosis and acute variceal bleeding: a multicenter observational study.

BACKGROUND AND AIM: Baveno VII workshop recommends management of acute variceal bleeding (AVB) in cirrhotic patients with nonmalignant portal vein thrombosis (PVT) should be performed according to the guidelines for patients without PVT. Nevertheless, whether PVT affects the outcome of patients with cirrhosis and AVB remains unclear. The aim of this study was to assess the clinical impact of PVT on the outcomes in the pre-emptive TIPSS eligible patients with cirrhosis and AVB. METHODS: From December 2010 to June 2016, 1219 consecutive cirrhotic patients admitted due to AVB with (n = 151; 12.4%) or without PVT (n = 1068; 87.6%), who received drug plus endoscopic treatment (a combination of vasoactive drugs, antibiotics, and endoscopic ligation for AVB, followed by beta-blockers plus variceal ligation for prevention of rebleeding) were retrospectively included. Fine and Gray competing risk regression models were taken to evaluate the impact of PVT on clinical outcomes after adjusting for potential confounders. RESULTS: During follow-up, 211 patients (17.3%) died, 490 (40.2%) experienced further bleeding, and 78 (6.4%) experienced new or worsening ascites within 1 year. Compared with those without PVT, patients with PVT had a similar risk of mortality (PVT vs no-PVT: 19.9% vs 16.7% at 1 year; adjusted HR 0.88, 95%CI 0.51-1.52, p = 0.653), further bleeding (47.0% vs 39.2% at 1 year, adjusted HR 1.19, 95% CI 0.92-1.53, p = 183), and new or worsening ascites (7.9% vs 9.6%, adjusted HR 0.70, 95% CI 0.39-1.28, p = 0.253) after adjusting for confounders in multivariable models. These findings were consistent across different relevant subgroups and confirmed by propensity score matching analysis. CONCLUSIONS: Our study showed no evidence that the PVT was associated with an improved or worsened outcome among cirrhotic patients with AVB who received standard treatment.

CLIF-C AD score predicts survival benefit from pre-emptive TIPS in individuals with Child-Pugh B cirrhosis and acute variceal bleeding.

Background & Aims: Among individuals with Child-Pugh B cirrhosis and acute variceal bleeding (AVB), the Baveno VII workshop recommended pre-emptive TIPS in those with a Child-Pugh score of 8-9 and active bleeding at initial endoscopy (Child B8-9 + AB criteria). Nevertheless, whether this criterion is superior to the CLIF-Consortium acute decompensation score (CLIF-C ADs) remains unclear. Methods: Data on 1,021 consecutive individuals with Child-Pugh B cirrhosis and AVB from 13 university hospitals in China who were treated with pre-emptive TIPS (n = 297) or drug plus endoscopic treatment (n = 724) between 2010 to 2019 were retrospectively analysed. A competing risk regression model was used to compare the outcomes between the two groups after adjusting for confounders. The concordance-statistic for benefit (c-for-benefit) was used to evaluate a models' ability to predict treatment benefit (risk difference between treatment groups). Results: Pre-emptive TIPS was associated with reduced mortality compared to drug plus endoscopic treatment (adjusted hazard ratio 0.62, 95% CI 0.44 to 0.88). A higher baseline CLIF-C AD score was associated with greater survival benefit (i.e., larger absolute mortality risk reduction). After adjusting for confounders, a survival benefit was observed in individuals with CLIF-C ADs ≥48 or Child-Pugh B8-9 with active bleeding, but not in those with CILF-C ADs <48, no active bleeding or Child-Pugh B7 with active bleeding. The c-for-benefit of CILF-C ADs for predicting survival benefit was higher than that of Child B8-9+AB criteria. Conclusions: In individuals with Child-Pugh B cirrhosis and AVB, CLIF-C ADs predicts survival benefit from pre-emptive TIPS and outperforms the Child B8-9+AB criteria. Prospective validation should be performed to confirm this result, especially for other aetiologies of cirrhosis. Impact and implications: In this study, among individuals with Child-Pugh B cirrhosis and acute variceal bleeding, the CLIF-Consortium acute decompensation (CLIF-C AD) score could predict the survival benefit from pre-emptive TIPS, with patients with higher CLIF-C AD scores benefiting more from pre-emptive TIPS. Furthermore, the CLIF-C AD score outperformed the Child B8-9 plus active bleeding criteria in terms of discriminating between those who obtained more benefit vs. less benefit from pre-emptive TIPS. Depending on prospective validation, the CLIF-C AD score could be used as the model of choice to determine who should undergo pre-emptive TIPS.

Dynamic projection of ecological risk in the Manas River basin based on terrain gradients.

With large-scale developments, the Manas River Basin (MRB) is in an extreme imbalance especially in land use, thus causing a series of ecological problems. A reliable dynamic ecological risk assessment is expected to provide useful information for the economic development. Through coupling spatial Cellular Automaton-Markov (CA-Markov) model and Landsat satellite images in 2000, 2008 and 2016, we forecasted the land use maps in 2024 and 2032. Based on the ecological risk model, we evaluated the ecological risk at landscape level from 2000 to 2032. More importantly, an improved evaluation of ecological risk was proposed based on terrain gradients and the correlation between terrain niche index (TNI) and future ecological risk was analyzed. The results showed that the artificial oases and urban are expanding, while the natural grassland is shrinking. Corresponding to the rapid development stage and stable consolidation stage, farmland will be followed by a slower increase (2016-2032) after a rapid increase (2000-2016), and water decreases first but then is projected to recover. As the overall spatial diversity increasing, the ecological risk in the whole basin is growing, especially in grassland. Compared with the stable critical state in artificial landscape, the future ecological risks in natural landscape tend to increase due to the cumulative effects of human activities. Also, we found that the great ecological risk mainly happens in "high altitude and complex terrain" or "low altitude and flat terrain" areas. The future ecological risk in medium terrain niche index (TNI) gradient will increase, while it will decrease in the lowest. Above all, the proposed framework can do well in forecasting ecological risk at landscape level, and can help simply infer the changes of ecological risk based on terrain.

Hydrological simulation and uncertainty analysis using the improved TOPMODEL in the arid Manas River basin, China.

Understanding the mechanism of complicated hydrological processes is important for sustainable management of water resources in an arid area. This paper carried out the simulations of water movement for the Manas River Basin (MRB) using the improved semi-distributed Topographic hydrologic model (TOPMODEL) with a snowmelt model and topographic index algorithm. A new algorithm is proposed to calculate the curve of topographic index using internal tangent circle on a conical surface. Based on the traditional model, the improved indicator of temperature considered solar radiation is used to calculate the amount of snowmelt. The uncertainty of parameters for the TOPMODEL model was analyzed using the generalized likelihood uncertainty estimation (GLUE) method. The proposed model shows that the distribution of the topographic index is concentrated in high mountains, and the accuracy of runoff simulation has certain enhancement by considering radiation. Our results revealed that the performance of the improved TOPMODEL is acceptable and comparable to runoff simulation in the MRB. The uncertainty of the simulations resulted from the parameters and structures of model, climatic and anthropogenic factors. This study is expected to serve as a valuable complement for widely application of TOPMODEL and identify the mechanism of hydrological processes in arid area.

Study on the characteristics of future precipitation in response to external changes over arid and humid basins.

The simulation abilities of the Coupled Model Inter-comparison Project Phase 5 (CMIP5) models to the arid basin (the Tarim River Basin, TRB) and humid basin (the Yangtze River Basin, YRB) were evaluated, determining the response of precipitation to external changes over typical basins. Our study shows that the future temporal and spatial variation characteristics of precipitation are different in different regions with the CMIP5. The annual and seasonal changes in precipitation were analyzed for the RCP2.6, RCP4.5 and RCP8.5 during 2021~2100 compared to those during 1961~2005. Precipitation shows an increasing trend in the TRB, but which decreases and then increases in the YRB, with a turning point in the middle of twenty-first Century. The ranges in annual precipitation increase with the increase in the scenario emissions in the future. Note that the Tarim River Basin is more vulnerable to the impact of emissions, especially for annual or spring and winter precipitation. Based on the uncertainty of CMIP5 data, the links between future precipitation changes and the elevation and relief amplitude were evaluated. The change of precipitation decreases with elevation, relief amplitude in the TRB, while it increases with elevation but decreases with relief amplitude in the YRB.

Identification of potential impacts of climate change and anthropogenic activities on streamflow alterations in the Tarim River Basin, China.

Understanding contributions of climate change and human activities to changes in streamflow is important for sustainable management of water resources in an arid area. This study presents quantitative analysis of climatic and anthropogenic factors to streamflow alteration in the Tarim River Basin (TRB) using the double mass curve method (DMC) and the Budyko methods. The time series (1960~2015) are divided into three periods: the prior impacted period (1960~1972) and the two post impacted periods, 1973~1986 and 1987~2015 with trend analysis. Our results suggest that human activities played a dominant role in deduction in the streamflow in TRB with contribution of 144.6% to 120.68% during the post impacted period I and 228.68% to 140.38% during the post impacted period II. Climatic variables accounted for 20.68%~44.6% of the decrease during the post impacted period I and 40.38% ~128.68% during the post impacted period II. Sensitivity analysis indicates that the streamflow alteration was most sensitive to changes in landscape parameters. The aridity index and all the elasticities showed an obvious increasing trend from the upstream to the downstream in the TRB. Our study suggests that it is important to take effective measures for sustainable development of eco-hydrological and socio-economic systems in the TRB.

Quantitative Assessment of Hydrological Alteration Caused by Irrigation Projects in the Tarim River basin, China.

The Tarim River is the longest inland river at an arid area in China. Deterioration in its ecohydrological system has received much attention world widely. This study presents quantitative assessment of hydrological alterations in the hydrological regime of the Tarim River caused by reservoir irrigation and channel irrigation over a period of over a half century. The improved indicators of hydrologic alteration and range of variability approach were applied to the daily flow rates at the two representative hydrological stations. Our study shows that the annual extreme water conditions (1-, 3-, 7-day annual minimum and extreme low timing) have been altered, compared with the pre-impact period. The average flow rate in July, the 30-day annual maximum flow rates, the date for the maximum rate, the rise rate, and the fall rate show a significant decreasing trend. The improved overall degree of hydrological alteration for the two stations are approximately 68.7% and 61.8%, suggesting a high degree of alteration. This study greatly improved our understanding of impacts of irrigations on the ecohydrological characteristics in the Tarim River.

CO2 Accounting and Risk Analysis for CO2 Sequestration at Enhanced Oil Recovery Sites.

Using CO2 in enhanced oil recovery (CO2-EOR) is a promising technology for emissions management because CO2-EOR can dramatically reduce sequestration costs in the absence of emissions policies that include incentives for carbon capture and storage. This study develops a multiscale statistical framework to perform CO2 accounting and risk analysis in an EOR environment at the Farnsworth Unit (FWU), Texas. A set of geostatistical-based Monte Carlo simulations of CO2-oil/gas-water flow and transport in the Morrow formation are conducted for global sensitivity and statistical analysis of the major risk metrics: CO2/water injection/production rates, cumulative net CO2 storage, cumulative oil/gas productions, and CO2 breakthrough time. The median and confidence intervals are estimated for quantifying uncertainty ranges of the risk metrics. A response-surface-based economic model has been derived to calculate the CO2-EOR profitability for the FWU site with a current oil price, which suggests that approximately 31% of the 1000 realizations can be profitable. If government carbon-tax credits are available, or the oil price goes up or CO2 capture and operating expenses reduce, more realizations would be profitable. The results from this study provide valuable insights for understanding CO2 storage potential and the corresponding environmental and economic risks of commercial-scale CO2-sequestration in depleted reservoirs.

Reactive Transport Modeling of the Enhancement of Density-Driven CO2 Convective Mixing in Carbonate Aquifers and its Potential Implication on Geological Carbon Sequestration.

We study the convection and mixing of CO2 in a brine aquifer, where the spread of dissolved CO2 is enhanced because of geochemical reactions with the host formations (calcite and dolomite), in addition to the extensively studied, buoyancy-driven mixing. The nonlinear convection is investigated under the assumptions of instantaneous chemical equilibrium, and that the dissipation of carbonate rocks solely depends on flow and transport and chemical speciation depends only on the equilibrium thermodynamics of the chemical system. The extent of convection is quantified in term of the CO2 saturation volume of the storage formation. Our results suggest that the density increase of resident species causes significant enhancement in CO2 dissolution, although no significant porosity and permeability alterations are observed. Early saturation of the reservoir can have negative impact on CO2 sequestration.

Integrated Framework for Assessing Impacts of CO2 Leakage on Groundwater Quality and Monitoring-Network Efficiency: Case Study at a CO2 Enhanced Oil Recovery Site.

This study presents a combined use of site characterization, laboratory experiments, single-well push-pull tests (PPTs), and reactive transport modeling to assess potential impacts of CO2 leakage on groundwater quality and leakage-detection ability of a groundwater monitoring network (GMN) in a potable aquifer at a CO2 enhanced oil recovery (CO2 EOR) site. Site characterization indicates that failures of plugged and abandoned wells are possible CO2 leakage pathways. Groundwater chemistry in the shallow aquifer is dominated mainly by silicate mineral weathering, and no CO2 leakage signals have been detected in the shallow aquifer. Results of the laboratory experiments and the field test show no obvious damage to groundwater chemistry should CO2 leakage occur and further were confirmed with a regional-scale reactive transport model (RSRTM) that was built upon the batch experiments and validated with the single-well PPT. Results of the RSRTM indicate that dissolved CO2 as an indicator for CO2 leakage detection works better than dissolved inorganic carbon, pH, and alkalinity at the CO2 EOR site. The detection ability of a GMN was assessed with monitoring efficiency, depending on various factors, including the natural hydraulic gradient, the leakage rate, the number of monitoring wells, the aquifer heterogeneity, and the time for a CO2 plume traveling to the monitoring well.

Field demonstration of CO2 leakage detection in potable aquifers with a pulselike CO2-release test.

This study presents two field pulselike CO2-release tests to demonstrate CO2 leakage detection in a shallow aquifer by monitoring groundwater pH, alkalinity, and dissolved inorganic carbon (DIC) using the periodic groundwater sampling method and a fiber-optic CO2 sensor for real-time in situ monitoring of dissolved CO2 in groundwater. Measurements of groundwater pH, alkalinity, DIC, and dissolved CO2 clearly deviated from their background values, showing responses to CO2 leakage. Dissolved CO2 observed in the tests was highly sensitive in comparison to groundwater pH, DIC, and alkalinity. Comparison of the pulselike CO2-release tests to other field tests suggests that pulselike CO2-release tests can provide reliable assessment of geochemical parameters indicative of CO2 leakage. Measurements by the fiber-optic CO2 sensor, showing obvious leakage signals, demonstrated the potential of real-time in situ monitoring of dissolved CO2 for leakage detection at a geologic carbon sequestration (GCS) site. Results of a two-dimensional reactive transport model reproduced the geochemical measurements and confirmed that the decrease in groundwater pH and the increases in DIC and dissolved CO2 observed in the pulselike CO2-release tests were caused by dissolution of CO2 whereas alkalinity was likely affected by carbonate dissolution.

Regional assessment of CO2-solubility trapping potential: a case study of the coastal and offshore Texas Miocene interval.

This study presents a regional assessment of CO2-solubility trapping potential (CSTP) in the Texas coastal and offshore Miocene interval, comprising lower, middle, and upper Miocene sandstone. Duan's solubility model [Duan et al. Mar. Chem. 2006, 98, 131-139] was applied to estimate carbon content in brine saturated with CO2 at reservoir conditions. Three approaches (simple, coarse, and fine) were used to calculate the CSTP. The estimate of CSTP in the study area varies from 30 Gt to 167 Gt. Sensitivity analysis indicated that the CSTP in the study area is most sensitive to storage efficiency, porosity, and thickness and is least sensitive to background carbon content in brine. Comparison of CSTP in our study area with CSTP values for seven other saline aquifers reported in the literature showed that the theoretical estimate of CO2-solubility trapping potential (TECSTP) has a linear relationship with brine volume, regardless of brine salinity, temperature, and pressure. Although more validation is needed, this linear relationship may provide a quick estimate of CSTP in a saline aquifer. Results of laboratory experiments of brine-rock-CO2 interactions and the geochemical model suggest that, in the study area, enhancement of CSTP caused by interactions between brine and rocks is minor and the storage capacity of mineral trapping owing to mineral precipitation is relatively trivial.

Inverse Modeling of Water-Rock-CO2 Batch Experiments: Potential Impacts on Groundwater Resources at Carbon Sequestration Sites.

This study developed a multicomponent geochemical model to interpret responses of water chemistry to introduction of CO2 into six water-rock batches with sedimentary samples collected from representative potable aquifers in the Gulf Coast area. The model simulated CO2 dissolution in groundwater, aqueous complexation, mineral reactions (dissolution/precipitation), and surface complexation on clay mineral surfaces. An inverse method was used to estimate mineral surface area, the key parameter for describing kinetic mineral reactions. Modeling results suggested that reductions in groundwater pH were more significant in the carbonate-poor aquifers than in the carbonate-rich aquifers, resulting in potential groundwater acidification. Modeled concentrations of major ions showed overall increasing trends, depending on mineralogy of the sediments, especially carbonate content. The geochemical model confirmed that mobilization of trace metals was caused likely by mineral dissolution and surface complexation on clay mineral surfaces. Although dissolved inorganic carbon and pH may be used as indicative parameters in potable aquifers, selection of geochemical parameters for CO2 leakage detection is site-specific and a stepwise procedure may be followed. A combined study of the geochemical models with the laboratory batch experiments improves our understanding of the mechanisms that dominate responses of water chemistry to CO2 leakage and also provides a frame of reference for designing monitoring strategy in potable aquifers.

Potential impacts of CO2 leakage on groundwater chemistry from laboratory batch experiments and field push-pull tests.

Storage of CO2 in deep saline reservoirs has been proposed to mitigate anthropogenically forced climate change. If injected CO2 unexpectedly migrates upward in shallow groundwater resources, potable groundwater may be negatively affected. This study examines the effects of an increase in pCO2 (partial pressure of CO2) on groundwater chemistry in a siliclastic-dominated aquifer by comparing a laboratory batch experiment and a field single-well push-pull test on the same aquifer sediment and groundwater. Although the aquifer mineralogy is predominately siliclastic, carbonate dissolution is the primary geochemical reaction. In the batch experiment, Ca concentrations increase until calcite saturation is reached at ~500 h. The concentrations of the elements Ca, Mg, Sr, Ba, Mn, and U are controlled by carbonate dissolution. Silicate dissolution controls Si and K concentrations and is ~2 orders of magnitude slower than carbonate dissolution. Changing pH conditions through the experiment initially mobilize Mo, V, Zn, Se, and Cd; sorption reactions later remove these elements from solution and concentrations drop to pre-experiment levels. The EPA's primary and secondary MCL's are not exceeded except for Mn, which exceeded the EPA's secondary standard of 0.05 mg/L. Push-pull results also identify carbonate and silicate dissolution reactions ~2 orders of magnitude slower than batch experiments.

Visual symptoms and G-induced loss of consciousness in 594 Chinese Air Force aircrew--a questionnaire survey.

A questionnaire survey was performed for the first time to assess the prevalence of visual symptoms and G-induced loss of consciousness (G-LOC) due to +Gz exposure in the Chinese Air Force (CAF) to determine the effectiveness of current G tolerance training. Responses were received from 594 individuals. Among them, 302 reported at least one episode of some sort of symptoms related to +Gz, including 110 (18.5%) with visual blurring, 231 (38.9%) with greyout, 111 (18.7%) with blackout, and 49 (8.2%) with G-LOC. Incidences were most common in aircrew with 250-1,000 flying hours (53.6%) and were more prevalent in those with fewer on type flying hours (p < 0.001). The most common situation was reported between +5 and 5.9 Gz. The results indicate a fairly high prevalence of visual symptoms and G-LOC among Chinese Air Force aircrew. There remains considerable scope for +Gz education, particularly in the early centrifuge training and selection of rational physical exercises.

The effects of low-impact dance on knee torque and lower extremity mobility in middle-aged and older women.

BACKGROUND: Although low-impact dance is one of the most prevalent exercises in older persons, little is known about its effects on knee torque and range of motion (ROM) in lower extremity joints. PURPOSE: The aim of this study was to examine the effects of low-impact dance on knee torque and lower extremity joint ROM in older women. METHODS: Twenty-six low-impact dancers and 12 physically inactive individuals comprised the dance group (DG) and the control group (CG), respectively. The knee extension torque, knee and ankle ROMs, and bone mineral density in calcanei were measured for all participants. RESULTS: Several ROMs of the lower extremity joints in the dominant leg, ankle inversion, plantarflexion, and dorsiflexion were significantly higher in the DG than in the CG (p < .05). In addition, the ankle inversion of the nondominant leg in the DG was also significantly higher than that in the CG. The knee extension torque of the nondominant leg in the DG was significantly higher than that in the CG (p < .05). CONCLUSION: Although this study did not focus on the efficacy of a particular intervention type, the results showed that low-impact dance can help achieve higher lower extremity ROM and knee torque values than attained by inactive individuals. It is hoped that this exposition of positive benefits will encourage further studies related to the effect of low-impact dance intervention on reducing fall risk.

Modelling geochemical and microbial consumption of dissolved oxygen after backfilling a high level radiactive waste repository.

Dissolved oxygen (DO) left in the voids of buffer and backfill materials of a deep geological high level radioactive waste (HLW) repository could cause canister corrosion. Available data from laboratory and in situ experiments indicate that microbes play a substantial role in controlling redox conditions near a HLW repository. This paper presents the application of a coupled hydro-bio-geochemical model to evaluate geochemical and microbial consumption of DO in bentonite porewater after backfilling of a HLW repository designed according to the Swedish reference concept. In addition to geochemical reactions, the model accounts for dissolved organic carbon (DOC) respiration and methane oxidation. Parameters for microbial processes were derived from calibration of the REX in situ experiment carried out at the Aspö underground laboratory. The role of geochemical and microbial processes in consuming DO is evaluated for several scenarios. Numerical results show that both geochemical and microbial processes are relevant for DO consumption. However, the time needed to consume the DO trapped in the bentonite buffer decreases dramatically from several hundreds of years when only geochemical processes are considered to a few weeks when both geochemical reactions and microbially-mediated DOC respiration and methane oxidation are taken into account simultaneously.