BACKGROUND Smartwatches have become readily accessible tools for detecting atrial fibrillation(AF).There remains limited data on how they affect psychosocial outcomes and engagement in older adults.We examine the heal...BACKGROUND Smartwatches have become readily accessible tools for detecting atrial fibrillation(AF).There remains limited data on how they affect psychosocial outcomes and engagement in older adults.We examine the health behavior outcomes of stroke survivors prescribed smartwatches for AF detection stratified by age.METHODS We analyzed data from the Pulsewatch study,a randomized controlled trial that enrolled patients(≥50 years)with a history of stroke or transient ischemic attack and CHA2DS2-VASc≥2.Intervention participants were equipped with a cardiac patch monitor and a smartwatch-app dyad,while control participants wore the cardiac patch monitor for up to 44 days.We evaluated health behavior parameters using standardized tools,including the Consumer Health Activation Index,the Generalized Anxiety Disorder questionnaire,the 12-Item Short Form Health Survey,and wear time of participants categorized into three age groups:Group 1(ages 50-60),Group 2(ages 61-69),and Group 3(ages 70-87).We performed statistical analysis using a mixedeffects repeated measures linear regression model to examine differences amongst age groups.RESULTS Comparative analysis between Groups 1,2 and 3 revealed no significant differences in anxiety,patient activation,perception of physical health and wear time.The use of smartwatch technology was associated with a decrease in perception of mental health for Group 2 compared to Group 1(β=-3.29,P=0.046).CONCLUSION Stroke survivors demonstrated a willingness to use smartwatches for AF monitoring.Importantly,among these study participants,the majority did not experience negative health behavior outcomes or decreased engagement as age increased.展开更多
In this paper,for the first time,we investigated the combined effect of subsurface dams and a typical stratified aquifer(two high-permeability layers with a low-permeability layer between them)on groundwater flow and ...In this paper,for the first time,we investigated the combined effect of subsurface dams and a typical stratified aquifer(two high-permeability layers with a low-permeability layer between them)on groundwater flow and salinity distribution in a tidally influenced coastal unconfined aquifer.Subsurface dams can inhibit the invasion of saltwater,and the low-permeability layer(LPL)and tide action can increase the effect of subsurface dams and the removal rate of residual saltwater.Through sensitivity analysis,it was discovered that shifting the dam location towards the inland resulted in a reduction in the effective heights of the dam.The upper saline plume contracted with increasing dam height,and the upper boundary of LPL was moved to shallower regions.And the natural removal time increased significantly with increasing dam height and the bottom boundary of LPL was moved to deeper regions.In addition,if the dam location was close to the sea boundary and the bottom boundary of LPL was moved to deeper regions,we could increase the subsurface dam height to reduce the risks of control of saltwater intrusion.This study provides us a comprehensive understanding of the complex hydrodynamics of saltwater intrusion and provides guides for the design of subsurface dams aimed at saltwater intrusion control in stratified coastal aquifers.展开更多
Dynamic performance on solids flow with water in deviated tubing is essential for the reliability of pump and normal operation of horizontal and directional wells.Compared with coal-water flow in vertical tubing and s...Dynamic performance on solids flow with water in deviated tubing is essential for the reliability of pump and normal operation of horizontal and directional wells.Compared with coal-water flow in vertical tubing and sand-oil flow with high production in deviated tubing,solids deposition with water shows obvious non-symmetric distributions in deviated tubing from simulations and experiments.The mathematical model of two phase flow was developed under coupling conditions of deviated tubing,low flow rate and viscosity based on the kinetic theory of granular flow and first-order discrete scheme.The results show that solid-water stratified flow in deviated tubing can be divided into two zones of suspension bed and the moving bed throughout the flow field.The solid flowing velocity with water is negative and particles slide down at the bottom of moving bed zone.The process of solids flow with water in deviated tubing will produce pressure loss and consume the kinetic energy.The thickness of deposited layer and the flowing velocity of solids flow downward with water at the moving bed zone enhance with the decreased inlet flow rate and the increased particle size,tubing inside diameter(ID)and inclination angle.Solids are easier into suspension from the upper part of moving bed zone to suspension bed zone and more solid particles flow with water towards the tubing outlet with the increase of inlet flowing velocity.The decision is made to reduce the screen width,tubing ID and inclination angle to maintain to be greater than critical deposition velocity in order to prevent solids settling.And it provides the theoretical basis and technical reserves for solid control and offers an effective approach to enhance tubing cleaning in deviated strings.展开更多
In this study,the damping responses of uniform soil,equi-proportional fly ash,and local soil as a single unit were investigated.The large-strain cyclic triaxial tests were performed for the specimen compacted at the d...In this study,the damping responses of uniform soil,equi-proportional fly ash,and local soil as a single unit were investigated.The large-strain cyclic triaxial tests were performed for the specimen compacted at the desired density(95%e99%of maximum dry density).The compacted specimens were tested under the loading frequency of 0.3e1 Hz with medium confinement of 70e100 kPa.Also,the unsymmetrical behavior of the hysteresis loop was analyzed using three different damping estimation approaches,i.e.symmetric hysteresis loop(SHL),asymmetric hysteresis loop(ASHL),and the modified American Society for Testing and Materials(ASTM)method.The outcome of the study shows for fly ash,local soil,and layered soil-ash,the ASHL technique has the highest damping value,followed by ASTM and then the SHL approach.The specimens prepared under high density and subjected to high confinement show low damping values.However,the specimens tested at high frequency exhibits high damping behavior.Similarly,the damping value of fly ash determined using the SHL and ASHL methods has a similar profile and reaches a maximum at 1%shear strain value before decreasing.The composite stratified deposit exhibits more dependency on relative compaction,confining pressure,and less on loading frequency.Based on the results,it is highly recommended to use the ASHL approach,especially under large strain conditions irrespective of soil type.The maximum damping ratio of stratified deposits is always in between the damping ratio of local soil and fly ash.The damping ratio of stratified soil and local soil is slightly larger than that of the other soils,although the damping ratio of fly ash is equivalent to that of the sand and clayey soil.These results may be helpful in the accurate determination of the damping properties of the layered soil-ash system that is required in the seismic response analysis.展开更多
Wax deposition in oil-water stratified flow is commonly encountered onshore and offshore oil production pipe systems,and typically reduces transportation capacity of oil.The accurate predicted model of wax deposition ...Wax deposition in oil-water stratified flow is commonly encountered onshore and offshore oil production pipe systems,and typically reduces transportation capacity of oil.The accurate predicted model of wax deposition has becomes an indispensable approach to design effective remediation strategies.However,a reliable mechanistic model for wax deposition prediction in oil-water two-phase stratified pipe flow is lacking to validate the deposition process.In this work,a three-dimensional(axial,radial,and angular)robust wax deposit model for oil-water stratified circular pipe flow was developed.The model of formation of a gel deposit based on the first principles of rheology was developed,associated with the results obtained from hydrodynamics and heat/mass transfer simulations.The predictions for wax deposition are found to compare satisfactorily with experimental data with two different oils for single phase and four different water cuts for oil-water stratified pipe flow.It can be seen from the wax gelation mechanism that an increase in water cut can help to reduce the wall/oil-deposit interface shear stress,thereby leading to an increase in the degree of gelation as well as the deposit rate.Furthermore,a local deposit analysis in the circumferential direction was conducted,for water cut 75%and total flow rate 5 m3/h,which provided insights to understand that the thickness on pipe wall was roughly uniformly distributed locates near the top of the pipe and the nearer the position gets close to two points,where the oil-water interface contacts the inner wall,the deposition thickness quickly dropped to 0.It was attributed to the fact that a roughly uniformly thickness far away from the oil-water interface contact the inner wall resulted in the slowly changes temperature along the circumferential pipe wall wetted by oil.展开更多
BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)has been extensively used to treat portal hypertension-associated complications,including cirrhosis.The prediction of post-TIPS prognosis is important for ...BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)has been extensively used to treat portal hypertension-associated complications,including cirrhosis.The prediction of post-TIPS prognosis is important for cirrhotic patients,as more aggressive liver transplantation is needed when the post-TIPS prognosis is poor.AIM To construct a nutrition-based model that could predict the disease progression of cirrhotic patients after TIPS implantation in a sex-dependent manner.METHODS This study retrospectively recruited cirrhotic patients undergoing TIPS implantation for analysis.Muscle quality was assessed by measuring the skeletal muscle index(SMI)by computed tomography.Multivariate Cox proportional hazard models were utilized to determine the association between SMI and disease progression in cirrhotic patients after TIPS implantation.RESULTS This study eventually included 186 cirrhotic patients receiving TIPS who were followed up for 30.5±18.8 mo.For male patients,the 30-mo survival rate was significantly lower and the probability of progressive events was higher(3.257-fold)in the low-level SMI group than in the high-level SMI group.According to the multivariate Cox analysis of male patients,SMI<32.8 was an independent risk factor for long-term adverse outcomes after TIPS implantation.A model was constructed,which involved creatinine,plasma ammonia,SMI,and acute-on-chronic liver failure and hepatic encephalopathy occurring within half a year after surgery.This model had an area under the receiver operating characteristic curve of 0.852,sensitivity of 0.926,and specificity of 0.652.According to the results of the DeLong test,this model outperformed other models(Child-Turcotte-Pugh,Model for End-Stage Liver Disease,and Freiburg index of post-TIPS survival)(P<0.05).CONCLUSION SMI is strongly associated with poor long-term outcomes in male patients with cirrhosis who underwent TIPS implantation.展开更多
A stratified wake has multiple flow regimes,and exhibits different behaviors in these regimes due to the competing physical effects of momentum and buoyancy.This work aims at automated classification of the weakly and...A stratified wake has multiple flow regimes,and exhibits different behaviors in these regimes due to the competing physical effects of momentum and buoyancy.This work aims at automated classification of the weakly and the strongly stratified turbulence regimes based on information available in a full Reynolds stress model.First,we generate a direct numerical simulation database with Reynolds numbers from 10,000 to 50,000 and Froude numbers from 2 to 50.Order(100)independent realizations of temporally evolving wakes are computed to get converged statistics.Second,we train a linear logistic regression classifier with weight thresholding for automated flow regime classification.The classifier is designed to identify the physics critical to classification.Trained against data at one flow condition,the classifier is found to generalize well to other Reynolds and Froude numbers.The results show that the physics governing wake evolution is universal,and that the classifier captures that physics.展开更多
This research focused on the study of heat and mass transfers in a two-phase stratified turbulent fluid flow in a geothermal pipe with chemical reaction. The derived non-linear partial differential equations governing...This research focused on the study of heat and mass transfers in a two-phase stratified turbulent fluid flow in a geothermal pipe with chemical reaction. The derived non-linear partial differential equations governing the flow were solved using the Finite Difference Method. The effects of various physical parameters on the concentration, skin friction, heat, and mass transfers have been determined. Analysis of the results obtained indicated that the coefficient of skin friction decreased with an increase in Reynolds number and solutal Grasholf number, the rate of heat transfer increased with an increase in Eckert number, Prandtl number, and angle of inclination, and the rate of mass transfer increased with increase in Reynolds number, Chemical reaction parameter and angle of inclination. The findings would be useful to engineers in designing and maintaining geothermal pipelines more effectively.展开更多
Invasive stratified mucin-producing carcinoma(ISMC)is a recently described histologic variant of high-risk human papillomavirus(HPV)-associated endocervical adenocarcinoma,as the putative invasive counterpart of the s...Invasive stratified mucin-producing carcinoma(ISMC)is a recently described histologic variant of high-risk human papillomavirus(HPV)-associated endocervical adenocarcinoma,as the putative invasive counterpart of the stratified mucin-producing intraepithelial lesion(SMILE).ISMC can display variable architectural patterns and usually coexists with other more conventional types of HPV-associated carcinomas,which makes diagnosis and differential diagnosis of ISMC is difficult for pathologists.Moreover,the prognosis of ISMC is still controversial.We analyzed 6 ISMCs with detailed pathological and clinical information.Intraepithelial lesion,including 1 high-grade squamous intraepithelial lesion and 1 SMILE,was found.Various architectures were observed(including nest,glandular,solid,trabecular,and single cell).Nuclear peripheral palisading,apoptotic bodies and mitoses,and variable cytoplasmic mucin vacuoles were seen in all of our cases.The predominance of neutrophils infiltration was seen in only 1 tumor.All the tumors infiltrated the cervical stroma in Silva pattern C manner.p63 and/or p40 was characteristically expressed in the peripheral cells in only 2 cases.High-risk HPV infection was observed in 3/3 detected cases.All the patients were alive during the follow-up time.Recognition of this infrequent tumor may help pathologists and oncologists for an accurate diagnosis and a better understanding of the clinicopathological behavior.展开更多
This paper mainly addresses maximum likelihood estimation for a response-selective stratified sampling scheme, the basic stratified sampling (BSS), in which the maximum subsample size in each stratum is fixed. We deri...This paper mainly addresses maximum likelihood estimation for a response-selective stratified sampling scheme, the basic stratified sampling (BSS), in which the maximum subsample size in each stratum is fixed. We derived the complete-data likelihood for BSS, and extended it as a full-data likelihood by incorporating incomplete data. We also similarly extended the empirical proportion likelihood approach for consistent and efficient estimation. We conducted a simulation study to compare these two new approaches with the existing estimation methods in BSS. Our result indicates that they perform as well as the standard full information likelihood approach. Methods were illustrated using a growth model for fish size at age, including between-individual variability. One of our major conclusions is that the fully observed BSS data, the partially observed data used for stratification, and the sampling strategy are all important in constructing a consistent and efficient estimator.展开更多
The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher voc...The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher vocational education and quality-oriented education. This thesis argues for the need of stratified English teaching in high vocational colleges.展开更多
Multiple filling of gobs will lead to a layered structure of the backfill.To explore the influence of layering structure on the mechanical properties and failure modes of backfill,different backfill specimens were pre...Multiple filling of gobs will lead to a layered structure of the backfill.To explore the influence of layering structure on the mechanical properties and failure modes of backfill,different backfill specimens were prepared with a cement/sand ratio of 1:4,a slurry concentration of 75%,and backfilling times of 1,2,3 and 4,separately.Triaxial cyclic loading and unloading experiments were carried out.The results show that with an increase in backfilling time,the peak strength of backfill decreases as a polynomial function and the peak strain increases as an exponential function.The cyclic load enhances the linear characteristic of backfill deformation.The loading and unloading deformation moduli have a linear negative correlation with the backfilling time.The unloading deformation modulus is always slightly higher than the loading deformation modulus.The failure modes of stratified backfill are mainly characterized by conjugate shear failure at the upper layer and tensile failure across the layer plane,and there is usually no damage in the lower layer away from the loading area.展开更多
The development of promising zinc anodes mainly suffers from their low plating/stripping coulombic efficiencies when using aqueous electrolyte,which are mainly associated with the interfacial formation of irreversible...The development of promising zinc anodes mainly suffers from their low plating/stripping coulombic efficiencies when using aqueous electrolyte,which are mainly associated with the interfacial formation of irreversible by-products.It is urgent to develop technologies that can solve this issue fundamentally.Herein,we report an artificial Sc_(2)O_(3) protective film to construct a new class of interface for Zn anode.The density functional theory simulation and experimental results have proven that the interfacial side reaction was inhibited via a stratified adsorption effect between this artificial layer and Zn anode.Benefiting from this novel structure,the Sc_(2)O_(3)-coated Zn anode can run for more than 100 cycles without short circuit and exhibit low voltage hysteresis,and the coulombic efficiency increases by 1.2%.Importantly,it shows a good application prospect when matched with two of popular manganese-based and vanadium-based cathodes.The excellent electrochemical performance of the Sc_(2)O_(3)-coated Zn anode highlights the importance of rational design of anode materials and demonstrates a good way for developing high-performance Zn anodes with long lifespan and high efficiency.展开更多
In this paper,the behavior of breakthrough curves(BTCs) for reactive solute transport through stratified porous media is investigated.A physical laboratory model for layered porous media was constructed,in which thin ...In this paper,the behavior of breakthrough curves(BTCs) for reactive solute transport through stratified porous media is investigated.A physical laboratory model for layered porous media was constructed,in which thin layer of gravel was sandwiched in between two thick layers of natural soil.Gravel layer and natural soil layers were hydraulically connected as single porous continuum.A constant source of tracer was connected through gravel layer and elucidated at different sampling points in the direction of flow.Flexible multiprocess non-equilibrium(MPNE) transport equation with scale-dependent dispersivity function was used to simulate experimental BTCs of reactive solute transport through layered porous media.The values of equilibrium sorption coefficient and other input parameters were obtained experimentally.The simulation of BTC was performed using MPNE model with scale-dependent dispersivity.The simulation of different scale-dependent dispersivities was then compared and it was found that for field scale of estimation of dispersivity,asymptotic and exponential dispersivity functions performed better.In continuation to the comparison of simulated BTCs obtained using different models,spatial moment analysis of each aforesaid scale-dependent dispersivity model was also done.Spatial moment analysis provides the information related to mean solute mass,rate of mass travel,and mean plume dispersion.Linear and constant dispersivities showed higher variance as compared to asymptotic and exponential dispersion functions.This supports the field applicability of asymptotic and exponential dispersivity functions.The BTCs were also found to elucidate a nonzero concentration with time,which was clearly affected by physical non-equilibrium.In natural condition,such information is required in effective aquifer remediation process.展开更多
The buckling failure of stratified rock slopes intersected by a set of steep discontinuities that are approximately parallel to the slope surface is frequently encountered while constructing railways and roadways in m...The buckling failure of stratified rock slopes intersected by a set of steep discontinuities that are approximately parallel to the slope surface is frequently encountered while constructing railways and roadways in mountainous areas. In this study, an analytical approach based on the energy equilibrium principle is presented to solve the flexural buckling stability of stratified rock slopes within the framework of multilayer beam theory. The generalized HoekBrown failure criterion is introduced to reflect the influences of slope size(scale effects) on the buckling stability. Subsequently, numerical and physical modellings from previous literatures are employed to validate the proposed approach. Furthermore, a practical case of Bawang Mountain landslide is also used for the comparative analysis. The study shows that the present analytical approach is capable to provide a more reasonable assessment for the buckling failure of stratified rock slopes, compared with several existing analytical approaches. Finally, a detailed parametric study is implemented, and the results indicate that the effects of rock strength, rock deformation modulus, geological strength index, layer thickness and disturbance degree of rock mass on the buckling failure of stratified rock slopes are more significant than that of rock type and slope angle.展开更多
The Counter-Propagation Deduction (CPD) method suggested by the authors is a new one for analyzing electromagnetic (EM) field in stratified media. The mechanism or the method is briefly introduced, and the rield in a ...The Counter-Propagation Deduction (CPD) method suggested by the authors is a new one for analyzing electromagnetic (EM) field in stratified media. The mechanism or the method is briefly introduced, and the rield in a layered medium in the presence or slant incidence of a perpendicularly or parallelly polarized electric wave is investigated. Some illustrative examples show that the method is capable of providing the direct mathematic expressions of the fields in an arbitrary layer, and is convenient for numerical evaluation through an unified program, irrespective of the number of medium layers.展开更多
The near wake of a circular cylinder in linearly stratified flows of finite depth was experimentally investigated by means of flow visualization and measurements of vortex shedding frequencies, at Reynolds numbers 3.5...The near wake of a circular cylinder in linearly stratified flows of finite depth was experimentally investigated by means of flow visualization and measurements of vortex shedding frequencies, at Reynolds numbers 3.5 × 103-1.2 × 104 and stratification parameters kd 0-2.0. The non-dimensional parameter kd is defined as kd = Nd/U, where N is the Brunt-Vaisala frequency, d, the diameter of the cylinder, and U, the approaching flow velocity. The study demonstrates that as kd increases from zero, the vortex shedding from a circular cylinder progressively strengthens, while the Strouhal number gradually becomes lower than that for homogeneous flow. This phenomenon can be explained by the effect of the increasingly stable stratification which enhances the two-dimensionality of the near-wake flow of the circular cylinder;the enhanced two-dimensionality of the flow strengthens the roll-up of the separated shear layer. Above a certain value of kd, however, vortex formation and shedding are strongly suppressed and the Strouhal number rises sharply. This observation is attributable to the development of stationary lee waves downstream of the circular cylinder because the lee waves strongly suppress vertical fluid motions.展开更多
Large eddy simulations(LESs) are performed to investigate the Cambridge premixed and stratified flames, SwB1 and SwB5, respectively. The flame surface density(FSD) model incorporated with two different wrinkling facto...Large eddy simulations(LESs) are performed to investigate the Cambridge premixed and stratified flames, SwB1 and SwB5, respectively. The flame surface density(FSD) model incorporated with two different wrinkling factor models, i.e., the Muppala and Charlette2 wrinkling factor models, is used to describe combustion/turbulence interaction, and the flamelet generated manifolds(FGM) method is employed to determine major scalars. This coupled sub-grid scale(SGS) combustion model is named as the FSD-FGM model. The FGM method can provide the detailed species in the flame which cannot be obtained from the origin FSD model. The LES results show that the FSD-FGM model has the ability of describing flame propagation, especially for stratified flames. The Charlette2 wrinkling factor model performs better than the Muppala wrinkling factor model in predicting the flame surface area change by the turbulence.The combustion characteristics are analyzed in detail by the flame index and probability distributions of the equivalence ratio and the orientation angle, which confirms that for the investigated stratified flame, the dominant combustion modes in the upstream and downstream regions are the premixed mode and the back-supported mode, respectively.展开更多
By using the theories on Stokes multicolored water waves and taking the two- layer ocean as a basic model of stratified ocean, the paper analyzes the problems related to the effects of the nonlinear water wave on offs...By using the theories on Stokes multicolored water waves and taking the two- layer ocean as a basic model of stratified ocean, the paper analyzes the problems related to the effects of the nonlinear water wave on offshore structures. A mathematical expression is presented to describe second order wave radiation conditions. Using integral principle, the analytical integral solutions are given to evaluate second order scattered wave loads on general vertical circular cylinders in the two-layer ocean, and the special recurrence formulas for infinite integrals over free and stratified surfaces are derived.展开更多
Molecular reconstruction is a rapid and reliable way to provide molecular detail of petroleum fractions,which is required in the kinetic modeling of petroleum conversation processes at the molecular level.In the typic...Molecular reconstruction is a rapid and reliable way to provide molecular detail of petroleum fractions,which is required in the kinetic modeling of petroleum conversation processes at the molecular level.In the typical stochastic reconstruction method,the estimation of properties of pseudo molecules that are generated by Monte Carlo sampling depends on the building of predefined molecular libraries,which is expensive and inaccessible for certain petroleum fractions.In this paper,a novel stochastic reconstruction strategy is proposed,which is based on a stratified library of structural descriptors.Properties of pseudo molecules generated in the novel strategy can be directly estimated by group contribution method in the condition of lacking predefined molecular libraries.In this strategy,the molecular building diagram comprises two steps.First,the ring structure is configured by determining the number of rings.Different from the length of chain adopted in the traditional stochastic reconstruction method,in the second step,number of structural descriptors(SDs)for binding site and chain were determined sequentially for the configuration of binding site and saturated acyclic hydrocarbon chain.These structural descriptors for binding site and chain were selected from group contribution methods.To count the number of partial overlapping sections between structural descriptors for chain,two supplementary structural descriptors were created.All possible saturated structures of hydrocarbon chains can be represented by structural descriptors at the scale of property estimation.This strategy separates the building of a predefined molecule library from the stochastic reconstruction process.The exact structures of pseudo molecules represented by structural descriptors in this work can be determined with sufficient chemical knowledge.Fifty naphtha samples are tested independently to demonstrate the performance of the proposed strategy and the results show that the estimated properties were close enough to the experimental values.This strategy will benefit the molecular management of petrochemical industries and therefore improve economic and environmental efficiencies.展开更多
基金funded by R01HL137734 from the National Heart,Lung,and Blood Institutesupported by F30HL149335 from the National Heart,Lung,and Blood Institute+3 种基金supported by NIH grant 2T32HL 120823supported by K23HL161432 from the National Heart,Lung,and Blood Institutesupported by R01 HL137734supported by R01HL126911,R01HL137734,R01HL137794,R01HL135219,R01HL136660,U54HL143541,and 1U01HL146382 from the National Heart,Lung,and Blood Institute.
文摘BACKGROUND Smartwatches have become readily accessible tools for detecting atrial fibrillation(AF).There remains limited data on how they affect psychosocial outcomes and engagement in older adults.We examine the health behavior outcomes of stroke survivors prescribed smartwatches for AF detection stratified by age.METHODS We analyzed data from the Pulsewatch study,a randomized controlled trial that enrolled patients(≥50 years)with a history of stroke or transient ischemic attack and CHA2DS2-VASc≥2.Intervention participants were equipped with a cardiac patch monitor and a smartwatch-app dyad,while control participants wore the cardiac patch monitor for up to 44 days.We evaluated health behavior parameters using standardized tools,including the Consumer Health Activation Index,the Generalized Anxiety Disorder questionnaire,the 12-Item Short Form Health Survey,and wear time of participants categorized into three age groups:Group 1(ages 50-60),Group 2(ages 61-69),and Group 3(ages 70-87).We performed statistical analysis using a mixedeffects repeated measures linear regression model to examine differences amongst age groups.RESULTS Comparative analysis between Groups 1,2 and 3 revealed no significant differences in anxiety,patient activation,perception of physical health and wear time.The use of smartwatch technology was associated with a decrease in perception of mental health for Group 2 compared to Group 1(β=-3.29,P=0.046).CONCLUSION Stroke survivors demonstrated a willingness to use smartwatches for AF monitoring.Importantly,among these study participants,the majority did not experience negative health behavior outcomes or decreased engagement as age increased.
基金The National Natural Science Foundation of China under contract No.51979095.
文摘In this paper,for the first time,we investigated the combined effect of subsurface dams and a typical stratified aquifer(two high-permeability layers with a low-permeability layer between them)on groundwater flow and salinity distribution in a tidally influenced coastal unconfined aquifer.Subsurface dams can inhibit the invasion of saltwater,and the low-permeability layer(LPL)and tide action can increase the effect of subsurface dams and the removal rate of residual saltwater.Through sensitivity analysis,it was discovered that shifting the dam location towards the inland resulted in a reduction in the effective heights of the dam.The upper saline plume contracted with increasing dam height,and the upper boundary of LPL was moved to shallower regions.And the natural removal time increased significantly with increasing dam height and the bottom boundary of LPL was moved to deeper regions.In addition,if the dam location was close to the sea boundary and the bottom boundary of LPL was moved to deeper regions,we could increase the subsurface dam height to reduce the risks of control of saltwater intrusion.This study provides us a comprehensive understanding of the complex hydrodynamics of saltwater intrusion and provides guides for the design of subsurface dams aimed at saltwater intrusion control in stratified coastal aquifers.
基金funded by National Natural Science Foundation of China(Grant No.52074161)National Science and Technology Major Project of China(Grant No.2016ZX05065-001)+2 种基金Taishan Scholar Project of Shandong Province(Grant No.tsqn202211177)Shandong Provincial Plan for Introduction and Cultivation of Young Pioneers in Colleges and Universities(Grant No.2021-QingChuang-30613019)Natural Science Foundation of Shandong Province(Grant No.ZR2022ME173).
文摘Dynamic performance on solids flow with water in deviated tubing is essential for the reliability of pump and normal operation of horizontal and directional wells.Compared with coal-water flow in vertical tubing and sand-oil flow with high production in deviated tubing,solids deposition with water shows obvious non-symmetric distributions in deviated tubing from simulations and experiments.The mathematical model of two phase flow was developed under coupling conditions of deviated tubing,low flow rate and viscosity based on the kinetic theory of granular flow and first-order discrete scheme.The results show that solid-water stratified flow in deviated tubing can be divided into two zones of suspension bed and the moving bed throughout the flow field.The solid flowing velocity with water is negative and particles slide down at the bottom of moving bed zone.The process of solids flow with water in deviated tubing will produce pressure loss and consume the kinetic energy.The thickness of deposited layer and the flowing velocity of solids flow downward with water at the moving bed zone enhance with the decreased inlet flow rate and the increased particle size,tubing inside diameter(ID)and inclination angle.Solids are easier into suspension from the upper part of moving bed zone to suspension bed zone and more solid particles flow with water towards the tubing outlet with the increase of inlet flowing velocity.The decision is made to reduce the screen width,tubing ID and inclination angle to maintain to be greater than critical deposition velocity in order to prevent solids settling.And it provides the theoretical basis and technical reserves for solid control and offers an effective approach to enhance tubing cleaning in deviated strings.
文摘In this study,the damping responses of uniform soil,equi-proportional fly ash,and local soil as a single unit were investigated.The large-strain cyclic triaxial tests were performed for the specimen compacted at the desired density(95%e99%of maximum dry density).The compacted specimens were tested under the loading frequency of 0.3e1 Hz with medium confinement of 70e100 kPa.Also,the unsymmetrical behavior of the hysteresis loop was analyzed using three different damping estimation approaches,i.e.symmetric hysteresis loop(SHL),asymmetric hysteresis loop(ASHL),and the modified American Society for Testing and Materials(ASTM)method.The outcome of the study shows for fly ash,local soil,and layered soil-ash,the ASHL technique has the highest damping value,followed by ASTM and then the SHL approach.The specimens prepared under high density and subjected to high confinement show low damping values.However,the specimens tested at high frequency exhibits high damping behavior.Similarly,the damping value of fly ash determined using the SHL and ASHL methods has a similar profile and reaches a maximum at 1%shear strain value before decreasing.The composite stratified deposit exhibits more dependency on relative compaction,confining pressure,and less on loading frequency.Based on the results,it is highly recommended to use the ASHL approach,especially under large strain conditions irrespective of soil type.The maximum damping ratio of stratified deposits is always in between the damping ratio of local soil and fly ash.The damping ratio of stratified soil and local soil is slightly larger than that of the other soils,although the damping ratio of fly ash is equivalent to that of the sand and clayey soil.These results may be helpful in the accurate determination of the damping properties of the layered soil-ash system that is required in the seismic response analysis.
基金The work received the support of by National Natural Science Foundation of China(52272338)Major Project of Science and Technology Research Program of Chongqing Education Commission of China(KJZD-M202212901,KJZD-K202012903)Young Elite Scientists Sponsorship Program(2020-JCJQ-QT-005).
文摘Wax deposition in oil-water stratified flow is commonly encountered onshore and offshore oil production pipe systems,and typically reduces transportation capacity of oil.The accurate predicted model of wax deposition has becomes an indispensable approach to design effective remediation strategies.However,a reliable mechanistic model for wax deposition prediction in oil-water two-phase stratified pipe flow is lacking to validate the deposition process.In this work,a three-dimensional(axial,radial,and angular)robust wax deposit model for oil-water stratified circular pipe flow was developed.The model of formation of a gel deposit based on the first principles of rheology was developed,associated with the results obtained from hydrodynamics and heat/mass transfer simulations.The predictions for wax deposition are found to compare satisfactorily with experimental data with two different oils for single phase and four different water cuts for oil-water stratified pipe flow.It can be seen from the wax gelation mechanism that an increase in water cut can help to reduce the wall/oil-deposit interface shear stress,thereby leading to an increase in the degree of gelation as well as the deposit rate.Furthermore,a local deposit analysis in the circumferential direction was conducted,for water cut 75%and total flow rate 5 m3/h,which provided insights to understand that the thickness on pipe wall was roughly uniformly distributed locates near the top of the pipe and the nearer the position gets close to two points,where the oil-water interface contacts the inner wall,the deposition thickness quickly dropped to 0.It was attributed to the fact that a roughly uniformly thickness far away from the oil-water interface contact the inner wall resulted in the slowly changes temperature along the circumferential pipe wall wetted by oil.
基金Supported by the Guizhou Senior Innovative Talent Project,No.QKHPTRC-GCC[2022]041-1.
文摘BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)has been extensively used to treat portal hypertension-associated complications,including cirrhosis.The prediction of post-TIPS prognosis is important for cirrhotic patients,as more aggressive liver transplantation is needed when the post-TIPS prognosis is poor.AIM To construct a nutrition-based model that could predict the disease progression of cirrhotic patients after TIPS implantation in a sex-dependent manner.METHODS This study retrospectively recruited cirrhotic patients undergoing TIPS implantation for analysis.Muscle quality was assessed by measuring the skeletal muscle index(SMI)by computed tomography.Multivariate Cox proportional hazard models were utilized to determine the association between SMI and disease progression in cirrhotic patients after TIPS implantation.RESULTS This study eventually included 186 cirrhotic patients receiving TIPS who were followed up for 30.5±18.8 mo.For male patients,the 30-mo survival rate was significantly lower and the probability of progressive events was higher(3.257-fold)in the low-level SMI group than in the high-level SMI group.According to the multivariate Cox analysis of male patients,SMI<32.8 was an independent risk factor for long-term adverse outcomes after TIPS implantation.A model was constructed,which involved creatinine,plasma ammonia,SMI,and acute-on-chronic liver failure and hepatic encephalopathy occurring within half a year after surgery.This model had an area under the receiver operating characteristic curve of 0.852,sensitivity of 0.926,and specificity of 0.652.According to the results of the DeLong test,this model outperformed other models(Child-Turcotte-Pugh,Model for End-Stage Liver Disease,and Freiburg index of post-TIPS survival)(P<0.05).CONCLUSION SMI is strongly associated with poor long-term outcomes in male patients with cirrhosis who underwent TIPS implantation.
基金This work is supported by ONR,contract N000142012315.
文摘A stratified wake has multiple flow regimes,and exhibits different behaviors in these regimes due to the competing physical effects of momentum and buoyancy.This work aims at automated classification of the weakly and the strongly stratified turbulence regimes based on information available in a full Reynolds stress model.First,we generate a direct numerical simulation database with Reynolds numbers from 10,000 to 50,000 and Froude numbers from 2 to 50.Order(100)independent realizations of temporally evolving wakes are computed to get converged statistics.Second,we train a linear logistic regression classifier with weight thresholding for automated flow regime classification.The classifier is designed to identify the physics critical to classification.Trained against data at one flow condition,the classifier is found to generalize well to other Reynolds and Froude numbers.The results show that the physics governing wake evolution is universal,and that the classifier captures that physics.
文摘This research focused on the study of heat and mass transfers in a two-phase stratified turbulent fluid flow in a geothermal pipe with chemical reaction. The derived non-linear partial differential equations governing the flow were solved using the Finite Difference Method. The effects of various physical parameters on the concentration, skin friction, heat, and mass transfers have been determined. Analysis of the results obtained indicated that the coefficient of skin friction decreased with an increase in Reynolds number and solutal Grasholf number, the rate of heat transfer increased with an increase in Eckert number, Prandtl number, and angle of inclination, and the rate of mass transfer increased with increase in Reynolds number, Chemical reaction parameter and angle of inclination. The findings would be useful to engineers in designing and maintaining geothermal pipelines more effectively.
基金the Scientific Research Funds Project of the Science and Technology Department of Sichuan Province(Grant No.21YYJC1616 to Liu Y).
文摘Invasive stratified mucin-producing carcinoma(ISMC)is a recently described histologic variant of high-risk human papillomavirus(HPV)-associated endocervical adenocarcinoma,as the putative invasive counterpart of the stratified mucin-producing intraepithelial lesion(SMILE).ISMC can display variable architectural patterns and usually coexists with other more conventional types of HPV-associated carcinomas,which makes diagnosis and differential diagnosis of ISMC is difficult for pathologists.Moreover,the prognosis of ISMC is still controversial.We analyzed 6 ISMCs with detailed pathological and clinical information.Intraepithelial lesion,including 1 high-grade squamous intraepithelial lesion and 1 SMILE,was found.Various architectures were observed(including nest,glandular,solid,trabecular,and single cell).Nuclear peripheral palisading,apoptotic bodies and mitoses,and variable cytoplasmic mucin vacuoles were seen in all of our cases.The predominance of neutrophils infiltration was seen in only 1 tumor.All the tumors infiltrated the cervical stroma in Silva pattern C manner.p63 and/or p40 was characteristically expressed in the peripheral cells in only 2 cases.High-risk HPV infection was observed in 3/3 detected cases.All the patients were alive during the follow-up time.Recognition of this infrequent tumor may help pathologists and oncologists for an accurate diagnosis and a better understanding of the clinicopathological behavior.
文摘This paper mainly addresses maximum likelihood estimation for a response-selective stratified sampling scheme, the basic stratified sampling (BSS), in which the maximum subsample size in each stratum is fixed. We derived the complete-data likelihood for BSS, and extended it as a full-data likelihood by incorporating incomplete data. We also similarly extended the empirical proportion likelihood approach for consistent and efficient estimation. We conducted a simulation study to compare these two new approaches with the existing estimation methods in BSS. Our result indicates that they perform as well as the standard full information likelihood approach. Methods were illustrated using a growth model for fish size at age, including between-individual variability. One of our major conclusions is that the fully observed BSS data, the partially observed data used for stratification, and the sampling strategy are all important in constructing a consistent and efficient estimator.
文摘The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher vocational education and quality-oriented education. This thesis argues for the need of stratified English teaching in high vocational colleges.
基金the National Natural Science Foundation of China(No.51374033)the Key Projects of the National Key Research and Development Program(No.YS2017YFSF040004).
文摘Multiple filling of gobs will lead to a layered structure of the backfill.To explore the influence of layering structure on the mechanical properties and failure modes of backfill,different backfill specimens were prepared with a cement/sand ratio of 1:4,a slurry concentration of 75%,and backfilling times of 1,2,3 and 4,separately.Triaxial cyclic loading and unloading experiments were carried out.The results show that with an increase in backfilling time,the peak strength of backfill decreases as a polynomial function and the peak strain increases as an exponential function.The cyclic load enhances the linear characteristic of backfill deformation.The loading and unloading deformation moduli have a linear negative correlation with the backfilling time.The unloading deformation modulus is always slightly higher than the loading deformation modulus.The failure modes of stratified backfill are mainly characterized by conjugate shear failure at the upper layer and tensile failure across the layer plane,and there is usually no damage in the lower layer away from the loading area.
基金supported by the National Natural Science Foundation of China(Grant no.51932011)。
文摘The development of promising zinc anodes mainly suffers from their low plating/stripping coulombic efficiencies when using aqueous electrolyte,which are mainly associated with the interfacial formation of irreversible by-products.It is urgent to develop technologies that can solve this issue fundamentally.Herein,we report an artificial Sc_(2)O_(3) protective film to construct a new class of interface for Zn anode.The density functional theory simulation and experimental results have proven that the interfacial side reaction was inhibited via a stratified adsorption effect between this artificial layer and Zn anode.Benefiting from this novel structure,the Sc_(2)O_(3)-coated Zn anode can run for more than 100 cycles without short circuit and exhibit low voltage hysteresis,and the coulombic efficiency increases by 1.2%.Importantly,it shows a good application prospect when matched with two of popular manganese-based and vanadium-based cathodes.The excellent electrochemical performance of the Sc_(2)O_(3)-coated Zn anode highlights the importance of rational design of anode materials and demonstrates a good way for developing high-performance Zn anodes with long lifespan and high efficiency.
文摘In this paper,the behavior of breakthrough curves(BTCs) for reactive solute transport through stratified porous media is investigated.A physical laboratory model for layered porous media was constructed,in which thin layer of gravel was sandwiched in between two thick layers of natural soil.Gravel layer and natural soil layers were hydraulically connected as single porous continuum.A constant source of tracer was connected through gravel layer and elucidated at different sampling points in the direction of flow.Flexible multiprocess non-equilibrium(MPNE) transport equation with scale-dependent dispersivity function was used to simulate experimental BTCs of reactive solute transport through layered porous media.The values of equilibrium sorption coefficient and other input parameters were obtained experimentally.The simulation of BTC was performed using MPNE model with scale-dependent dispersivity.The simulation of different scale-dependent dispersivities was then compared and it was found that for field scale of estimation of dispersivity,asymptotic and exponential dispersivity functions performed better.In continuation to the comparison of simulated BTCs obtained using different models,spatial moment analysis of each aforesaid scale-dependent dispersivity model was also done.Spatial moment analysis provides the information related to mean solute mass,rate of mass travel,and mean plume dispersion.Linear and constant dispersivities showed higher variance as compared to asymptotic and exponential dispersion functions.This supports the field applicability of asymptotic and exponential dispersivity functions.The BTCs were also found to elucidate a nonzero concentration with time,which was clearly affected by physical non-equilibrium.In natural condition,such information is required in effective aquifer remediation process.
基金the financial support of the National Natural Science Foundation of China (Grant No.51579032, 51509173, U1765107)Fundamental Research Funds for the Central Universities (Grant No.DUT16ZD211, DUT17ZD205)
文摘The buckling failure of stratified rock slopes intersected by a set of steep discontinuities that are approximately parallel to the slope surface is frequently encountered while constructing railways and roadways in mountainous areas. In this study, an analytical approach based on the energy equilibrium principle is presented to solve the flexural buckling stability of stratified rock slopes within the framework of multilayer beam theory. The generalized HoekBrown failure criterion is introduced to reflect the influences of slope size(scale effects) on the buckling stability. Subsequently, numerical and physical modellings from previous literatures are employed to validate the proposed approach. Furthermore, a practical case of Bawang Mountain landslide is also used for the comparative analysis. The study shows that the present analytical approach is capable to provide a more reasonable assessment for the buckling failure of stratified rock slopes, compared with several existing analytical approaches. Finally, a detailed parametric study is implemented, and the results indicate that the effects of rock strength, rock deformation modulus, geological strength index, layer thickness and disturbance degree of rock mass on the buckling failure of stratified rock slopes are more significant than that of rock type and slope angle.
文摘The Counter-Propagation Deduction (CPD) method suggested by the authors is a new one for analyzing electromagnetic (EM) field in stratified media. The mechanism or the method is briefly introduced, and the rield in a layered medium in the presence or slant incidence of a perpendicularly or parallelly polarized electric wave is investigated. Some illustrative examples show that the method is capable of providing the direct mathematic expressions of the fields in an arbitrary layer, and is convenient for numerical evaluation through an unified program, irrespective of the number of medium layers.
文摘The near wake of a circular cylinder in linearly stratified flows of finite depth was experimentally investigated by means of flow visualization and measurements of vortex shedding frequencies, at Reynolds numbers 3.5 × 103-1.2 × 104 and stratification parameters kd 0-2.0. The non-dimensional parameter kd is defined as kd = Nd/U, where N is the Brunt-Vaisala frequency, d, the diameter of the cylinder, and U, the approaching flow velocity. The study demonstrates that as kd increases from zero, the vortex shedding from a circular cylinder progressively strengthens, while the Strouhal number gradually becomes lower than that for homogeneous flow. This phenomenon can be explained by the effect of the increasingly stable stratification which enhances the two-dimensionality of the near-wake flow of the circular cylinder;the enhanced two-dimensionality of the flow strengthens the roll-up of the separated shear layer. Above a certain value of kd, however, vortex formation and shedding are strongly suppressed and the Strouhal number rises sharply. This observation is attributable to the development of stationary lee waves downstream of the circular cylinder because the lee waves strongly suppress vertical fluid motions.
基金Project supported by the National Natural Science Foundation of China(Nos.91441117 and51576182)
文摘Large eddy simulations(LESs) are performed to investigate the Cambridge premixed and stratified flames, SwB1 and SwB5, respectively. The flame surface density(FSD) model incorporated with two different wrinkling factor models, i.e., the Muppala and Charlette2 wrinkling factor models, is used to describe combustion/turbulence interaction, and the flamelet generated manifolds(FGM) method is employed to determine major scalars. This coupled sub-grid scale(SGS) combustion model is named as the FSD-FGM model. The FGM method can provide the detailed species in the flame which cannot be obtained from the origin FSD model. The LES results show that the FSD-FGM model has the ability of describing flame propagation, especially for stratified flames. The Charlette2 wrinkling factor model performs better than the Muppala wrinkling factor model in predicting the flame surface area change by the turbulence.The combustion characteristics are analyzed in detail by the flame index and probability distributions of the equivalence ratio and the orientation angle, which confirms that for the investigated stratified flame, the dominant combustion modes in the upstream and downstream regions are the premixed mode and the back-supported mode, respectively.
基金National Natural Science Foundation of China (19802023)
文摘By using the theories on Stokes multicolored water waves and taking the two- layer ocean as a basic model of stratified ocean, the paper analyzes the problems related to the effects of the nonlinear water wave on offshore structures. A mathematical expression is presented to describe second order wave radiation conditions. Using integral principle, the analytical integral solutions are given to evaluate second order scattered wave loads on general vertical circular cylinders in the two-layer ocean, and the special recurrence formulas for infinite integrals over free and stratified surfaces are derived.
基金the support of International(Regional)Cooperation and Exchange Project(61720106008)National Natural Science Fund for Distinguished Young Scholars(61925305)National Natural Science Foundation of China(61873093)。
文摘Molecular reconstruction is a rapid and reliable way to provide molecular detail of petroleum fractions,which is required in the kinetic modeling of petroleum conversation processes at the molecular level.In the typical stochastic reconstruction method,the estimation of properties of pseudo molecules that are generated by Monte Carlo sampling depends on the building of predefined molecular libraries,which is expensive and inaccessible for certain petroleum fractions.In this paper,a novel stochastic reconstruction strategy is proposed,which is based on a stratified library of structural descriptors.Properties of pseudo molecules generated in the novel strategy can be directly estimated by group contribution method in the condition of lacking predefined molecular libraries.In this strategy,the molecular building diagram comprises two steps.First,the ring structure is configured by determining the number of rings.Different from the length of chain adopted in the traditional stochastic reconstruction method,in the second step,number of structural descriptors(SDs)for binding site and chain were determined sequentially for the configuration of binding site and saturated acyclic hydrocarbon chain.These structural descriptors for binding site and chain were selected from group contribution methods.To count the number of partial overlapping sections between structural descriptors for chain,two supplementary structural descriptors were created.All possible saturated structures of hydrocarbon chains can be represented by structural descriptors at the scale of property estimation.This strategy separates the building of a predefined molecule library from the stochastic reconstruction process.The exact structures of pseudo molecules represented by structural descriptors in this work can be determined with sufficient chemical knowledge.Fifty naphtha samples are tested independently to demonstrate the performance of the proposed strategy and the results show that the estimated properties were close enough to the experimental values.This strategy will benefit the molecular management of petrochemical industries and therefore improve economic and environmental efficiencies.
