Transient elastography with controlled attenuation parameter for the diagnosis of colorectal polyps in patients with nonalcoholic fatty liver disease

BACKGROUND The severity of nonalcoholic fatty liver disease(NAFLD)and lipid metabolism are related to the occurrence of colorectal polyps.Liver-controlled attenuation parameters(liver-CAPs)have been established to predict the prognosis of hepatic steatosis patients.AIM To explore the risk factors associated with colorectal polyps in patients with NAFLD by analyzing liver-CAPs and establishing a diagnostic model.METHODS Patients who were diagnosed with colorectal polyps in the Department of Gastroenterology of our hospital between June 2021 and April 2022 composed the case group,and those with no important abnormalities composed the control group.The area under the receiver operating characteristic curve was used to predict the diagnostic efficiency.Differences were considered statistically significant when P<0.05.RESULTS The median triglyceride(TG)and liver-CAP in the case group were significantly greater than those in the control group(mmol/L,1.74 vs 1.05;dB/m,282 vs 254,P<0.05).TG and liver-CAP were found to be independent risk factors for colorectal polyps,with ORs of 2.338(95%CI:1.154–4.733)and 1.019(95%CI:1.006–1.033),respectively(P<0.05).And there was no difference in the diagnostic efficacy between liver-CAP and TG combined with liver-CAP(TG+CAP)(P>0.05).When the liver-CAP was greater than 291 dB/m,colorectal polyps were more likely to occur.CONCLUSION The levels of TG and liver-CAP in patients with colorectal polyps are significantly greater than those patients without polyps.Liver-CAP alone can be used to diagnose NAFLD with colorectal polyps.

Transient elastography(Fibro Scan~?) with controlled attenuation parameter in the assessment of liver steatosis and fibrosis in patients with nonalcoholic fatty liver disease- Where do we stand?

Non-alcoholic fatty liver disease(NAFLD) is the most common cause of chronic liver disease worldwide. Currently, the routinely used modalities are unable to adequately determine the levels of steatosis and fibrosis(laboratory tests and ultrasonography) or cannot be applied as a screening procedure(liver biopsy). Among the non-invasive tests, transient elastography(Fibro Scan?, TE) with controlled attenuation parameter(CAP) has demonstrated good accuracy in quantifying the levels of liver steatosis and fibrosis in patients with NAFLD, the factors associated with the diagnosis and NAFLD progression. The method is fast, reliable and reproducible, with good intra- and interobserver levels of agreement, thus allowing for population-wide screening and disease follow-up. The initial inability of the procedure to accurately determine fibrosis and steatosis in obese patients has been addressed with the development of the obese-specific XL probe. TE with CAP is a viable alternative to ultrasonography, both as an initial assessment and during follow-up of patients with NAFLD. Its ability to exclude patients with advanced fibrosis may be used to identify low-risk NAFLD patients in whom liver biopsy is not needed, therefore reducing the risk of complications and the financial costs.

High value of controlled attenuation parameter predicts a poor antiviral response in patients with chronic hepatits B

BACKGROUND: Controlled attenuation parameter (CAP) is a non-invasive method for diagnosing hepatic steatosis based on vibration-controlled transient elastography. The objective of this study was to investigate the effect of high value of CAP on antiviral therapy in patients with chronic hepatitis B (CHB). METHODS: Patients with CHB receiving enticavir for initial antiviral therapy were studied; they were divided into the high CAP group and normal CAP group at baseline according to the CAP values. The effect of the antiviral therapy between the two groups were compared at week 12, 24 and 48. Patients with high CAP value at baseline were divided into three subgroups, mild, moderate and severe elevation; the therapeutic response were compared among patients with normal CAP and subgroups of patients with elevated CAP. RESULTS: A total of 153 patients were enrolled. Among them, 63 were in the high CAP group and 90 in the normal CAP group. Patients with high CAP had lower rates of ALT normalization and HBV DNA clearance in response to antiviral therapy compared with those with normal CAP at week 12, 24 and 48. Further analysis showed that the rate of ALT normalization in patients with mildly and moderately elevated CAP were significant lower than those with normal CAP at week 12 and 24; while the difference was not significant between the patients with normal CAP and those with severely elevated CAP. The rate of HBV DNA clearance was significantly lower in patients with severely elevated CAP compared with those with normal CAP at week 12, 24 and 48. CONCLUSION: CHB patients with high CAP had poor response to antiviral therapy.

Controlled attenuation parameter for non-invasive assessment of hepatic steatosis in Chinese patients

AIM:To evaluate the performance of a novel non-invasive controlled attenuation parameter(CAP)to assess liver steatosis.METHODS:This was a multi-center prospective cohort study.Consecutive patients(aged≥18 years)who had undergone percutaneous liver biopsy and CAP measurement were recruited from three Chinese liver centers.Steatosis was categorized as S0:<5%;S1:5%-33%;S2:34%-66%;or S3:≥67%,according to the nonalcoholic fatty liver disease(NAFLD)activity score.The FibroScan?502 equipped with the M probe(Echosens,Paris,France)was used to capture both CAP and liver stiffness measurement values simultaneously.Receiver operating characteristic curves were plotted,and the areas under the curves were calculated to determine the diagnostic efficacy.The accuracy of the CAP values at the optimal thresholds was defined by maximizing the sum of sensitivity and specificity(maximum Youden index).RESULTS:A total of 152 patients were recruited,including 52(34.2%)patients with NAFLD and 100(65.8%)with chronic hepatitis B(CHB)virus infection.After adjustment,the steatosis grade(OR=37.12;95%CI:21.63-52.60,P<0.001)and body mass index(BMI,OR=6.20;95%CI:2.92-9.48,P<0.001)were found independently associated with CAP by multivariate linear regression analysis.CAP was not influenced by inflammation,fibrosis or aetiology.The median CAP values and interquartile ranges among patients with S0,S1,S2 and S3 steatosis were 211(181-240)dB/m,270(253-305)dB/m,330(302-360)dB/m,and 346(313-363)dB/m,respectively.The cut-offs for the CAP values in all patients with steatosis≥5%,≥34%and≥67%were 253 dB/m,285 dB/m and 310 dB/m,respectively.The areas under the curves were 0.92,0.92and 0.88 for steatosis≥5%,≥34%and≥67%,respectively.No significant differences were found in the CAP values between the NAFLD group and the CHB group in each steatosis grade.CONCLUSION:CAP appears to be a promising tool for the non-invasive detection and quantification of hepatic steatosis,but is limited by BMI.

Evaluation of controlled attenuation parameter in assessing hepatic steatosis in patients with autoimmune liver diseases

BACKGROUND Hepatic steatosis commonly occurs in some chronic liver diseases and may affect disease progression.AIM To investigate the performance of controlled attenuation parameter(CAP)for the diagnosis of hepatic steatosis in patients with autoimmune liver diseases(AILDs).METHODS Patients who were suspected of having AILDs and underwent liver biopsy were consistently enrolled.Liver stiffness measurement(LSM)and CAP were performed by transient elastography.The area under the receiver operating characteristic(AUROC)curve was used to evaluate the performance of CAP for diagnosing hepatic steatosis compared with biopsy.RESULTS Among 190 patients with biopsy-proven hepatic steatosis,69 were diagnosed with autoimmune hepatitis(AIH),18 with primary biliary cholangitis(PBC),and 27 with AIH-PBC overlap syndrome.The AUROCs of CAP for the diagnosis of steatosis in AILDS were 0.878(0.791-0.965)for S1,0.764(0.676-0.853)for S2,and 0.821(0.716-0.926)for S3.The CAP value was significantly related to hepatic steatosis grade(P<0.001).Among 69 patients with AIH,the median CAP score was 205.63±47.36 dB/m for S0,258.41±42.83 dB/m for S1,293.00±37.18 dB/m for S2,and 313.60±27.89 dB/m for S3.Compared with patients with nonalcoholic fatty liver disease(NAFLD)presenting with autoimmune markers,patients with AIH concomitant with NAFLD were much older and had higher serum IgG levels and LSM values.CONCLUSION CAP can be used as a noninvasive diagnostic method to evaluate hepatic steatosis in patients with AILDs.Determination of LSM combined with CAP may help to identify patients with AIH concomitant with NAFLD from those with NAFLD with autoimmune phenomena.

Controlled attenuation parameter for evaluating liver steatosis in chronic viral hepatitis

AIM:To assess the performance of controlled attenuation parameter(CAP)in patients with chronic viral hepatitis.METHODS:CAP is a new technique that measures the attenuation in the liver of an ultrasound beam,which is directly related to lipid accumulation.Consecutive patients undergoing liver biopsy for chronic viral hepatitis were studied using the M probe of FibroScan device(Echosens,Paris,France).The device estimates liver st-eatosis in decibel per meter(dB/m).An expert operator performed all measurements.Steatosis was graded according to Kleiner’s classification.Pearson or Spearman rank coefficient was used to test correlation between two study variables.Linear regression was used for multivariate model to assess the association between CAP and other variables.Receiver operating characteristic curve analysis was performed to calculate area under the curve(AUROC)for S0 vs S1-S3 and S0-S1 vs S2-S3.RESULTS:115 subjects(85 males and 30 females)were prospectively studied.The mean values of CAP were 227.1±43.1 for S0;254.6±38.9 for S1;297.8±49.4 dB/m for S2-S3.In univariate analysis CAP showed a significant correlation with age,body mass index(BMI),degree of steatosis,and cholesterol.Multivariate regression analysis confirmed the correlation with the degree of steatosis[coefficient,1.2(0.60-1.83);P<10-5]and BMI[coefficient,4.1(0.5-7.8);P=0.03]but not with all other variables.Optimal cutoff values for S≥1 and S≥2 were 219 dB/m[AUROC,0.76(0.67-0.84);sensitivity,91.1%(78.8-97.5);specificity,51.6%(38.7-64.2);positive predictive value,56.9%(44.7-68.6);negative predictive value,89.2%(74.3-97.0);positive likelihood ratio,1.88(1.4-2.5);negative likelihood ratio,0.17(0.07-0.5)]and 296 dB/m[AUROC,0.82(0.74-0.89);sensitivity,60.0%(32.3-83.7);specificity,91.5%(83.9-96.3);positive predictive value,52.9%(27.8-77.0);negative predictive value,93.5%(86.3-97.6);positive likelihood ratio,7.05(3.2-15.4);negative likelihood ratio,0.44(0.2-0.8)],respectively.CONCLUSION:Controlled attenuation parameter could be a useful tool in the clinical management of patients with chronic viral hepatitis for detecting liver steatosis.

Diagnostic value of controlled attenuation parameter for liver steatosis in patients with chronic hepatitis B

AIM:To study the diagnostic value of controlled attenuation parameter(CAP),evaluated by transient elastography,for liver steatosis in patients with chronic hepatitis B(CHB).METHODS:Eighty-eight patients with CHB were enrolled in this study.All of the patients were subjected to transient elastography to determine CAP.These patients also underwent liver biopsy in the same period.Using liver biopsy as a reference,we determined receiver operating characteristic(ROC)curves for different endpoints.Areas under the ROC curves(AUCs)were used to evaluate the diagnostic importance of CAP for liver steatosis in patients with CHB.RESULTS:A positive correlation was observed between the AUCs of CAP and liver pathological stage(r=0.582,P<0.05).CAP was not correlated with inflammation degree and fibrosis degree(r=-0.025,P>0.05;r=0.068,P>0.05).The mean CAP value at S0 was 209.59±41.25 dB/m,223.84±35.28 dB/m at S1,274.17±43.69 dB/m at S2,and 312.50±25.44dB/m at S3.CAP values among S0,S1,S2,and S3were significantly different(F=17.79,P<0.01).The AUC values for CAP were 0.711(0.592-0.870),0.868(0.748-0.989),and 0.974(0.922-1.026)for S1,S2,and S3,respectively.The optimal cut-off values were219.5,230.0,and 283.5 dB/m.CONCLUSION:CAP is a novel tool that can be used to assess the degree of steatosis.

Value of controlled attenuation parameter in fibrosis prediction in nonalcoholic steatohepatitis

BACKGROUND Liver stiffness measurement(LSM)tends to overestimate fibrosis stage in nonalcoholic fatty liver disease(NAFLD).Controlled attenuation parameter(CAP),provided by LSM device,has been introduced for noninvasive quantification of hepatic steatosis.AIM To determine the role of CAP values in predicting liver fibrosis stage by LSM in nonalcoholic steatohepatitis(NASH).METHODS One hundred eighty-four patients with biopsy proven NASH had LSM and CAP evaluated at baseline.Among them,130 patients had 1-year follow up LSM and analyzed for the changes of LSM after pioglitazone or ursodeoxycholic acid(UDCA)treatment.RESULTS In Kleiner fibrosis stage F0-1,LSM values increased at higher CAP tertile(P=0.001),and in F2,at middle and higher tertiles(P=0.027).No difference across CAP tertiles was noticed in F3-4(P=0.752).Receiver operating characteristic curve for LSM cutoff in diagnosis of F≥2 identified 8.05 kPa for lower CAP tertile,9.35 kPa for middle,and 10.55 kPa for high tertile.When changes in proportion of significant fibrosis(F≥2)were assessed among pioglitazone and UDCA treated patients considering CAP values,pioglitazone treated patients demonstrated decrease in proportion of high LSM.CONCLUSION In patient with NAFLD,interpretation of LSM in association with CAP scores may provide helpful information sparing unnecessary liver biopsy.

Parameter-dependent vibration-attenuation controller design for electro-hydraulic actuated linear structural systems

The problem of robust active vibration control for a class of electro-hydraulic actuated structural systems with time-delay in the control input channel and parameter uncertainties appearing in all the mass, damping and stiffness matrices is investigated in this paper. First, by introducing a linear varying parameter, the nonlinear system is described as a linear parameter varying （LPV） model. Second, based on this LPV model, an LMI-based condition for the system to be asymptotically stabilized is deduced. By solving these LMIs, a parameter-dependent controller is established for the closed- loop system to be stable with a prescribed level of disturbance attenuation. The condition is also extended to the uncertain case. Finally, some numerical simulations demonstrate the satisfying performance of the proposed controller.

An improved lumped parameter model predicting attenuation of earmuff with air leakage

Since air leakage is inevitable when earmuffs are worn improperly or together with safety glasses in factory or military,it is required to be considered to accurately predict earmuff attenuation.Besides unwanted air leakage,under controlled air leakage is introduced to earmuff to achieve adjustable attenuations in different signal-to-noise ratios(SNRs)and balance between attenuation and speech intelligibility.This work is to develop an improved lumped parameter model(LPM)to predict earmuff attenuation with consideration of air leakage.Air leakage paths are introduced into conventional LPM without air leakage,and air leakage path impedance is analytically described by Maa’s microperforated tube impedance.Earmuff passive attenuation behavior can be analytically described and analyzed with the improved LPM.Finally,the validity of improved LPM is verified experimentally.The results indicate that the improved LPM can predict earmuff attenuation with air leakage,and air leakage deteriorates earmuff attenuation and turns resonance frequency higher.

Tomography for Q of the Eastern Section of the Tianshan Area from High-frequency Attenuation of S-wave

Based on the waveform data of 5,076 local earthquakes recorded at 25 stations in Xinjiang during the period from 2009 to 2014 and the observation reports provided by the Xinjiang Digital Seismic Network,a data set of 19,140 attenuation factors t*is obtained by fitting the high-frequency attenuation of S-wave spectra with a genetic algorithm. The spatial distribution of Q_S is determined by inverting the t*data with seismic tomography. The results show that the average Q0 in eastern Tianshan is 520,and there is a significant correlation between the Q_S value distribution or attenuation characteristics it disclosed and the surface structure of the study area. The Q_S value is lower in the intersection area of the mountain basin which is located on the north and south sides of the Tianshan Mountains,and the high Q_S distribution is more concentrated inside the Tianshan orogenic belt. The M≥6. 0 earthquakes have been basically located in the Low-Q_S region since 1900. 24 high heat flow points in eastern Tianshan are located at the north and south of Tianshan Mountains where low Q_S exists,indicating a negative correlation. In addition,there is a positive correlation between the velocity structure and the attenuation structure in the study area,which reflects the consistency of the 2-D attenuation structure with the velocity structure and the two-dimensional density structure.

Attenuation Parameters of Blasting Vibration by Fuzzy Nonlinear Regression Analysis

In order to reduce the influence of outliers on the parameter estimate of the attenuation formula for the blasting vibration velocity,a fuzzy nonlinear regression method of Sadov’s vibration formula was proposed on the basis of the fuzziness of blasting engineering,and the algorithm was described in details as well.In accordance with an engineering case,the vibration attenuation formula was regressed by the fuzzy nonlinear regression method and the nonlinear least square method,respectively.The calculation results showed that the fuzzy nonlinear regression method is more suitable to the field test data.It differs from the nonlinear least square method because the weight of residual square in the objective function can be adjusted according to the membership of each data.And the deviation calculation of least square estimate of parameters in the nonlinear regression model verified the rationality of using the membership to assign the weight of residual square.The fuzzy nonlinear regression method provides a calculation basis for estimating Sadov’s vibration formula’s parameters more accurately.

Study on Inelastic Attenuation and Source Parameters of the Shidian Swarm in 2001

基于在云南地区性的数字网络的 6 个车站上记录的水平部件的数字震动图，我们 inversed 在用 Atkinson 方法和 6 的地点回答的 Shidian 群的来源区域的无弹性的变细用泥熔岩 method.The 在 Shidian 震中附近驻扎 200km 观察 seistoic 波形数据被移开繁殖改正，在在 2001 的 Shidian 群的来源参数前的仪器和地点效果用 ge 被决定????

Regional Finite-Fault Source Model for Development of Ground Motion Attenuation Relationship in Sichuan, China

The attenuation relationship of ground motion based on seismology has always been a front subject of engineering earthquake.Among them,the regional finite-fault source model is very important.In view of this point,the general characteristics of regional seism-tectonics,including the dip and depth of the fault plane,are emphasized.According to the statistics of regional seism-tectonics and focal mechanisms in Sichuan,China,and the sensitivity of estimated peak ground acceleration(PGA)attenuation is analyzed,and the dip angle is taken as an average of 70°.Based the statistics of the upper crustal structure and the focal depth of regional earthquakes,the bottom boundary of the sedimentary cover can be used as the upper limit for estimating the depth of upper-edge.The analysis shows that this value is sensitive to PGA.Based on the analysis of geometric relations,the corresponding calculation formula is used,and a set of concepts and steps for building the regional finite-fault source model is proposed.The estimation of source parameters takes into account the uncertainty,the geometric relationship among parameters and the total energy conservation.Meanwhile,a set of reasonable models is developed,which lay a foundation for the further study of regional ground motion attenuation based on seismology.

Lg-Q model and its implication on high-frequency ground motion for earthquakes in the Sichuan and Yunnan region

Low-rise buildings are susceptible to high-frequency ground motion.The high-frequency ground motions at regional distances are mainly controlled by crustal Lg waves whose amplitudes are typically much larger than those of body waves.In this study,we develop a Lg-wave Q model for the Sichuan and Yunnan region in the frequency band of 0.3–2.0 Hz using regional seismic records of 1166 earthquakes recorded at 152 stations.Comparison between the observed pattern of ground motion from real earthquake and model prediction demonstrates the robustness and effectiveness of our Lg-Q model.Then,assuming that the Lg-wave Q structure is the main factor affecting the propagation of the high-frequency ground motions,we calculate the spatial distributions of high-frequency ground motions from scenario earthquakes at different locations in the region using the average Lg-wave attenuation model over the frequency band of 0.3–2.0 Hz.We also use the Lg-Q model to estimate the distribution of cumulative energy of high-frequency ground motions based on the historical seismicity of the Sichuan and Yunnan region.Results show that the Lg-Q model can be used effectively in estimating the spatial distribution of high-frequency seismic energies and thus can contribute to the assessment of seismic hazard to low-rise buildings.

The electrical parameters measurement system for electrotome output based on Labview

An accurate detection of the effective values of electric voltage and current from high frequency power generators is a precondition for the development of smart electrotomes. In this light, an energy detection system based on personal computer (PC) is developed hereby. It senses voltage and current in isolation from generators with transformers, and then the measured values are amplified, filtered, transformed into single-ended signals and converted to RMS. The detected signals are transformed into digital signals through Data Acquisition Card (DAQ) and the data are processed with quadratic fit in Labview. Finally, the controller completes constant power output. The experiment results indicate that the energy detection system can measure the output parameters precisely and the controller can achieve constant power control.

An investigation on the ground motion parameters and seismic response of underground structures

Peak ground acceleration (PGA), frequency content and time duration are three fundamental parameters of seismic loading. This study focuses on the seismic load frequency and its effect on the underground structures. Eight accelerograms regarding different occurred earthquakes that are scaled to an identical PGA and variation of ground motion parameters with ratio of peak ground velocity (PGV) to PGA, as a parameter related to the load frequency, are considered. Then, concrete lining response of a circular tunnel under various seismic conditions is evaluated analytically. In the next, seismic response of underground structure is assessed numerically using two different time histories. Finally, effects of incident load frequency and frequency ratio on the dynamic damping of geotechnical materials are discussed. Result of analyses show that specific energy of seismic loading with identical PGA is related to the seismic load frequency. Furthermore, incident load frequency and natural frequency of a system have influence on the wave attenuation and dynamic damping of the system.

An inversion of site response and Lg attenuation using Lg waveform

Based on spectral ratio method, a joint inversion method was used to obtain parameters of Lg wave attenuation and site response. The inversion method allows simple and direct （two-parameter） determination of Lg wave attenuation and site response from sparse spectral data, which are not affected by radiation pattern factor and different response of same instrument after geometrical spreading. The method was used successfully for estimating site response of stations of Zhejiang Seismic Network and measuring Lg wave attenuation. The study is based on 20 earthquakes occurred in northeast of Taiwan with magnitude Ms5.0-6.7 and 960 seismic wave records from 16 stations in Zhejiang area from 2002 to 2005. The parameters of site response and Lg attenuation were calculated with a frequency interval of 0.2 Hz in the range of 0.5 Hz to 10 Hz. Lg wave attenuation coefficient corresponding to U-D, E-W and N-S components are γ（f）=0.00175f^0.43485, γ（f）=0.00145f^0.48467 and γ（f）=0.0021f^0.41241, respectively. It is found that the site response is component-independent. It is also found that the site response of QIY station is significant above the frequency of 1.5 Hz, and that the site response of NIB station is low for most frequency

The Study on the Strong Ground Motion Attenuation Relationship in the Pishan Area,Xinjiang Uygur Autonomous Region

Small earthquake data from the Pishan MS6.5 aftershocks is collected by the Xinjiang Regional Digital Seismic Observation Network.Five parameters of the focal region are obtained by micro genetic inversion:stress dropΔσof 75.95 bars,quality factor parameters Q0of 186.33 andηof 0.26,geometric attenuation parameters R1of 72.18km and R2of 139.70km.We calculate the Fourier spectrum and combine it with the random phase spectrum to get the ground motion time history,and build the strong motion acceleration attenuation relationship.The strong ground motion acceleration attenuation of the Pishan area is thus obtained.Because of the insufficiency of strong ground motion records,we added the records from the Wuqia MS6.9 earthquake on October 5,2008,the Akto MS6.2 earthquake on October 6,2008,and the Lop MS6.0 earthquake on March 9,2012 to the data.The comparison of the calculation results and the empirical attenuation relationships with strong ground motion records reveal that the strong motion data of Pishan and Lop earthquakes is higher than the empirical attenuation relationships.The Wuqia MS6.9 earthquake strong motion data is consistent with Yu Yanxiangs(2013)short axis result,and lower than the present result.

Application of Machine Learning Methods on Climate Data and Commercial Microwave Link Attenuations for Estimating Meteorological Visibility in Dusty Condition

Accurately measuring meteorological visibility is an important factor in road, sea, rail, and air transportation safety, especially under visibility-reducing weather events. This paper deals with the application of Machine Learning methods to estimate meteorological visibility in dusty conditions, from the power levels of commercial microwave links and weather data including temperature, dew point, wind speed, wind direction, and atmospheric pressure. Three well-known Machine Learning methods are investigated: Decision Trees, Random Forest, and Support Vector Machines. The correlation coefficient and the mean square error, between the visibility distances estimated by Machine Learning methods and those provided by Burkina Faso weather services are computed. Except for the SVM method, all the other methods give a correlation coefficient greater than 0.90. The Random Forest method presents the best result both in terms of correlation coefficient (0.97) and means square error (0.60). For this last method, the best variables that explain the model are selected by evaluating the weight of each variable in the model. The best performance is obtained by considering the attenuation of the microwave signal and the dew point.