A novel high-κ~ A1203/HfO2/AI203 nanolaminate charge trapping memory capacitor structure based on SiGe substrates with low interface densities is successfully fabricated and investigated. The memory capacitor exhibit...A novel high-κ~ A1203/HfO2/AI203 nanolaminate charge trapping memory capacitor structure based on SiGe substrates with low interface densities is successfully fabricated and investigated. The memory capacitor exhibits excellent program-erasable characteristics. A large memory window of ~4 V, a small leakage current density of ~2 ×10-6 Acre-2 at a gate voltage of 7V, a high charge trapping density of 1.42 × 1013 cm-2 at a working vo]tage of 4-10 V and good retention characteristics are observed. Furthermore, the programming （△ VFB = 2.8 V at 10 V for 10μs） and erasing speeds （△VFB =-1.7 V at -10 V for 10μs） of the fabricated capacitor based on SiGe substrates are significantly improved as compared with counterparts reported earlier. It is concluded that the high-κ Al2O3/HfO2/Al2O3 nanolaminate charge trapping capacitor structure based on SiGe substrates is a promising candidate for future nano-scaled nonvolatile flash memory applications.展开更多
We propose and investigate a novel metal/SiO_2/Si_3N_4/SiO_2/SiGe charge trapping flash memory structure（named as MONOS）, utilizing Si Ge as the buried channel. The fabricated memory device demonstrates excellent pr...We propose and investigate a novel metal/SiO_2/Si_3N_4/SiO_2/SiGe charge trapping flash memory structure（named as MONOS）, utilizing Si Ge as the buried channel. The fabricated memory device demonstrates excellent programerasable characteristics attributed to the fact that more carriers are generated by the smaller bandgap of Si Ge during program/erase operations. A flat-band voltage shift 2.8 V can be obtained by programming at ＋11 V for 100 us. Meanwhile, the memory device exhibits a large memory window of ~7.17 V under ±12 V sweeping voltage, and a negligible charge loss of 18% after 104 s＇ retention. In addition, the leakage current density is lower than 2.52 × 10^（-7） A·cm^（-2） below a gate breakdown voltage of 12.5 V. Investigation of leakage current-voltage indicates that the Schottky emission is the predominant conduction mechanisms for leakage current. These desirable characteristics are ascribed to the higher trap density of the Si_3N_4 charge trapping layer and the better quality of the interface between the SiO_2 tunneling layer and the Si Ge buried channel. Therefore, the application of the Si Ge buried channel is very promising to construct 3 D charge trapping NAND flash devices with improved operation characteristics.展开更多
This paper deals with the Gevreg-hypoellipticity for a class of totally characteristic operators with the elliptic condition and the discrete boundary spectrum condition respectively.
The Low Frequency Synchromotor Drive Mine Hoist System fed by the cycloinverter has good features from the technological and economical point of view. According to the erating char acteristic of the mine hoist system,...The Low Frequency Synchromotor Drive Mine Hoist System fed by the cycloinverter has good features from the technological and economical point of view. According to the erating char acteristic of the mine hoist system, an advanced analysis is given to the construction, the operating characteristics and the harmonics of the magnetomotive force of the synchromotor fed by the cy cloinverter, and the beneficial suggestions are also given in this paper.展开更多
We present a conceptual configuration of a high-temperature superconducting（HTS）magnet made from REBCO（Re=Rare Earth,B=Barium,C=Copper,O=Oxide）annular plates,called a Bitter-like HTS magnet,which can operate in pe...We present a conceptual configuration of a high-temperature superconducting（HTS）magnet made from REBCO（Re=Rare Earth,B=Barium,C=Copper,O=Oxide）annular plates,called a Bitter-like HTS magnet,which can operate in persistent current mode without joint resistance and can be excited by a flux pump and without current leads and a persistent power supply.An REBCO annular magnet which can generate 1.5 T corresponding to the operating current density 80%of critical current density of the magnet at an operating temperature of65 K is conceptually designed.Then the thermal stability of the magnet is numerically simulated by Comsol software.Whein a piece of RBCO annular plate quenches,the maximum released energy is its stored energy because each REBCO annular plate in the Bitter-like magnet is in parallel.To calculate the stored energy in the REBCO annular plate,the inductance of every annular plate,including self-inductance and mutual inductance,is calculated.Compared with the minimum quench energy（MQE）and stored energy in one REBCO annular plate,the stored energy in one REBCO annular plate is always smaller than the MQE,and the REBCO annular plate will not be damaged even though the stored energy in the REBCO annular plate is fully released,which indicates that this 1.5 T Bitter-like magnet has the property of self-protection.展开更多
The common propellants used for electric thrusters, such as xenon and krypton, are rare, expensive,and difficult to acquire. Solid iodine attracts much attention with the advantages of low cost,extensive availability,...The common propellants used for electric thrusters, such as xenon and krypton, are rare, expensive,and difficult to acquire. Solid iodine attracts much attention with the advantages of low cost,extensive availability, low vapor pressure, and ionization potential. The performance of a lowpower iodine-fed Hall thruster matched with a xenon-fed cathode is investigated across a broad range of operation conditions. Regulation of the iodine vapor's mass flow rates is stably achieved by using a temperature control method of the iodine reservoir. The thrust measurements are finished utilizing a thrust target during the tests. Results show that thrust and anode-specific impulse increase approximately linearly with the increasing iodine mass flow rate.At the nominal power of 200 W class, iodine mass flow rates are 0.62 and 0.93 mg/s, thrusts are7.19 and 7.58 m N, anode specific impulses are 1184 and 826 s, anode efficiencies are 20.8%and 14.5%, and thrust to power ratios are 35.9 and 37.9 m N/k W under the conditions of 250 V,0.8 A and 200 V, 1.0 A, respectively. The operating characteristics of iodine-fed Hall thruster are analyzed in different states. Further work on the measurements of plasma characteristics and experimental optimization will be carried out.展开更多
BACKGROUND:The study aimed to evaluate the predictive role of interleukin-6(IL-6)and chronic obstructive pulmonary disease(COPD)assessment test(CAT)score in mechanical ventilation(MV)in COPD patients at the acute exac...BACKGROUND:The study aimed to evaluate the predictive role of interleukin-6(IL-6)and chronic obstructive pulmonary disease(COPD)assessment test(CAT)score in mechanical ventilation(MV)in COPD patients at the acute exacerbation stage in the emergency department(ED).METHODS:For a one-year period,among adult patients in the ED who met the criteria of acute exacerbation of COPD,158 who received MV within 48 hours after admission were compared to 294 who didn't require MV within the same period after admission.IL-6 level and CAT score were compared between the two groups.The predicted value of IL-6 and CAT score was assessed by logistic regression analysis and a receiver operating characteristic(ROC)curve.RESULTS:The IL-6 and CAT scores in the 158 MV patients were much higher than those without.IL-6 and CAT scores were independent predictors of MV within 48 hours using logistic regression analysis(IL-6:odds ratio[OR]1.053,95%confidence interval[CI]1.039–1.067,P<0.001;CAT score:OR 1.122,95%CI 1.086–1.159,P<0.001).The combination of IL-6 and CAT scores(area under ROC curve[AUC]0.826,95%CI 0.786–0.866,P<0.001)improved the accuracy of predicting MV within 48 hours when compared with IL-6(AUC 0.752,95%CI 0.703–0.800,P<0.001)and CAT scores alone(AUC 0.739,95%CI 0.692–0.786,P<0.001).The sensitivity and specificity were 69.6%,74.1%,75.32%and 63.6%,respectively.CONCLUSION:The combined of IL-6 and CAT scores is useful for evaluating the risk of COPD patients at acute exacerbation in ED,and can provide a predictive value for MV or not within 48 hours.展开更多
Objective: Using receiver operating characteristics (ROC) curve to evaluate the value of pulse wave velocity (PWV) in the diagnosis of coronary heart disease (CHD). Methods: By using coronary angiography as golden dia...Objective: Using receiver operating characteristics (ROC) curve to evaluate the value of pulse wave velocity (PWV) in the diagnosis of coronary heart disease (CHD). Methods: By using coronary angiography as golden diagnostic standard of CHD, 218 patients were divided into both CHD group (n=121) and non-CHD group (n = 97). All these patients received PWV test. The efficacy of PWV of each artery segments in the diagnosis of CHD was evaluated by ROC curve. The sensitivity and specificity were calculated with the golden diagnostic standard of CHD. Results:The PWV of right carotid to femoral artery (Rc-f), left carotid to femoral artery (Lc-f), right radial to carotid artery (Rc-r), left radial to carotid artery (Lc-r) in CHD group were significantly higher than that of non-CHD group (9. 31±1. 75 vs 7.60±1.59, P<0. 01; 9. 02±1.71 vs 7. 52±1.50, P<0. 01; 8. 69±1. 37 vs 8. 00±1. 27, P<0. 01; 8.52±1. 03 vs 8. 03±1. 2, P<0. 01 respectively). However, the PWV of both right and left femoral to ankle artery (Rf-a and Lf-a) had no significant differences between the two groups. We then compared the area under curve (AUC) of each ROC(AUCROC) of PWV of Rc-f, Lc-f Rc-r and Lc-r to evaluate their diagnostic efficacy for CHD. We found that AUCROC of Rc-f PWV was the biggest (AUCROC = 0. 818), at the peak point of its ROC curve, the PWV was 8. 32 m/s. PWV>8. 32 m/s of Rc-f could predict the presence of CHD with a sensitivity of 79% and specificity of 77%. Conclusion: The PWV of Rc-f, Lc-f, Rc-r, Lc-r are significantly higher in CHD group than that in non-CHD group, and PWV of Rc-f is the most accurate in the detection of CHD. The PWV>8. 32 m/s of RC-F is a valuable predictor of CHD.展开更多
On the basis of strict mathematical description about Failure_Free Period Life Test (FFPLT), the statistical properties of the tests and optimal confidence limit of the parameter are discussed in detail and correspond...On the basis of strict mathematical description about Failure_Free Period Life Test (FFPLT), the statistical properties of the tests and optimal confidence limit of the parameter are discussed in detail and corresponding calculating formulae are found out.展开更多
Understanding the drivers of biological invasions in landscapes is a major goal in invasion ecology.The control of biological invasions has increasingly become critical in the past few decades because invasive species...Understanding the drivers of biological invasions in landscapes is a major goal in invasion ecology.The control of biological invasions has increasingly become critical in the past few decades because invasive species are thought to be a major threat to endemism.In this study,by examining the key variables that influence Acacia mearnsii,we sought to understand its potential invasion in eastern Zimbabwe.We used the maximum entropy(MaxEnt)method against a set of environmental variables to predict the potential invasion front of A.mearnsii.Our study showed that the predictor variables,i.e.,aspect,elevation,distance from streams,soil type and distance from the nearest A.mearnsii plantation adequately explained(training AUC=0.96 and test AUC=0.93)variability in the spatial distribution of invading A.mearnsii.The front of invasion by A.mearnsii seemed also to occur next to existing A.mearnsii plantations.Results from our study could be useful in identifying priority areas that could be targeted for controlling the spread of A.mearnsii in Zimbabwe and other areas under threat from A.mearnsii invasion.We recommend that the plantation owners pay for the control of A.mearnsii invasion about their plantations.展开更多
BACKGROUND:Spontaneous isolated superior mesenteric artery(SMA)dissection(SISMAD)is a rare cause of abdominal pain.The aim of the study is to investigate the role of a new parameter,the ratio of the SMA diameter to th...BACKGROUND:Spontaneous isolated superior mesenteric artery(SMA)dissection(SISMAD)is a rare cause of abdominal pain.The aim of the study is to investigate the role of a new parameter,the ratio of the SMA diameter to the superior mesenteric vein(SMV)diameter(SMA/SMV)based on non-enhanced computed tomography(CT),in the early diagnosis of SISMAD.METHODS:In a registry study from December 2013 to June 2021,97 abdominal pain SISMAD patients(SISMAD group)admitted to our hospital were enrolled.Meanwhile,the matched sex and age abdominal pain non-SISMAD patients at 1:2 were collected in reverse chronological order as the control group.Student’s t-test,Wilcoxon rank-sum test,and Chi-square test were used to compare differences between the SISMAD and control groups.Med Calc was used to generate receiver operating characteristic(ROC)curve.RESULTS:A total of 291 abdominal pain patients,including 97 SISMAD patients and 194 nonSISMAD patients,were included in the current study.The maximum SMA diameter,perivascular exudation,and SMA/SMV based on non-enhanced CT were significant between the two groups(all P<0.05).ROC curves showed that for the maximum SMA diameter,the area under the curve(AUC),cut-off,sensitivity,and specificity were 0.926,9.80,93.8%,and 79.4%,respectively.For SMA/SMV,its AUC,cut-off,sensitivity,and specificity were 0.956,0.83,88.7%,and 92.3%,respectively.The diagnostic efficiency of SMA/SMV was better than that of the maximum SMA diameter(P<0.05).The combined parameters of SMA/SMV and maximum SMA diameter had the best diagnostic efficiency(AUC=0.970).CONCLUSION:SMA/SMV may be a potential marker for SISMAD.展开更多
Objective： To assess the value of MR spectroscopy （MRS） in the diagnosis of prostate cancer by meta-analysis. Methods： Prospective studies were selected from the MEDLINE, Ovid, Embase databases, Springer, Elsevier...Objective： To assess the value of MR spectroscopy （MRS） in the diagnosis of prostate cancer by meta-analysis. Methods： Prospective studies were selected from the MEDLINE, Ovid, Embase databases, Springer, Elsevier, China National Knowledge Infrastructure. According to the suggestion, results were determined by the ratio of （Cho＋Cr）/Cit. If this ratio was less than 0.75, negative result was respectively determined, and the definitive tumor was diagnosed as this threshold. According to the assessment standard of Evidence-based Medicine, English and Chinese literature in Grade A and B on MRS imaging was included. According to homogeneity test, different effect models were chosen to calculate different pooled weighted values of sensitivity, specificity and the corresponding 95% confidence intervals （95% CI）. Summary receiver operating characteristic （SROC） curves were used to assess the results. Funnel plot was used to analyze publication bias. Results： According to the assessment standard of Evidence-based Medicine, only 5 papers in Grade B were included in this research. The pooled weighted sensitivity and its 95% confidence interval is 82% （73%, 89%） and the pooled weighted sensitivity and its 95% confidence interval is 68% （58%, 76%）. The AUC （area under curve） is 83.40%. An asymmetric funnel plot suggested two missing studies leading to publication bias. Conclusion： If the ratio of （Cho＋Cr）/Cit is regarded as the diagnostic criteria in detecting prostate cancer by MRS, meta-analysis suggests this method has a better diagnostic value to detect the malignant prostate mass but the sensitivity needs to be improved. We hope to support a method and requirement about diagnostic test. Performing perspective register and improving quality of study design is the only way to reduce the bias and get real information of disease.展开更多
基金Supported by the National Science and Technology Major Project of China under Grant No 2013ZX02303007the National Key Research and Development Program of China under Grant No 2016YFA0301701the Youth Innovation Promotion Association of the Chinese Academy of Sciences under Grant No 2016112
文摘A novel high-κ~ A1203/HfO2/AI203 nanolaminate charge trapping memory capacitor structure based on SiGe substrates with low interface densities is successfully fabricated and investigated. The memory capacitor exhibits excellent program-erasable characteristics. A large memory window of ~4 V, a small leakage current density of ~2 ×10-6 Acre-2 at a gate voltage of 7V, a high charge trapping density of 1.42 × 1013 cm-2 at a working vo]tage of 4-10 V and good retention characteristics are observed. Furthermore, the programming （△ VFB = 2.8 V at 10 V for 10μs） and erasing speeds （△VFB =-1.7 V at -10 V for 10μs） of the fabricated capacitor based on SiGe substrates are significantly improved as compared with counterparts reported earlier. It is concluded that the high-κ Al2O3/HfO2/Al2O3 nanolaminate charge trapping capacitor structure based on SiGe substrates is a promising candidate for future nano-scaled nonvolatile flash memory applications.
基金Supported by the National Science and Technology Major Project of China under Grant No 2013ZX02303007the National Key Research and Development Program of China under Grant No 2016YFA0301701the Youth Innovation Promotion Association of the Chinese Academy of Sciences under Grant No 2016112
文摘We propose and investigate a novel metal/SiO_2/Si_3N_4/SiO_2/SiGe charge trapping flash memory structure（named as MONOS）, utilizing Si Ge as the buried channel. The fabricated memory device demonstrates excellent programerasable characteristics attributed to the fact that more carriers are generated by the smaller bandgap of Si Ge during program/erase operations. A flat-band voltage shift 2.8 V can be obtained by programming at ＋11 V for 100 us. Meanwhile, the memory device exhibits a large memory window of ~7.17 V under ±12 V sweeping voltage, and a negligible charge loss of 18% after 104 s＇ retention. In addition, the leakage current density is lower than 2.52 × 10^（-7） A·cm^（-2） below a gate breakdown voltage of 12.5 V. Investigation of leakage current-voltage indicates that the Schottky emission is the predominant conduction mechanisms for leakage current. These desirable characteristics are ascribed to the higher trap density of the Si_3N_4 charge trapping layer and the better quality of the interface between the SiO_2 tunneling layer and the Si Ge buried channel. Therefore, the application of the Si Ge buried channel is very promising to construct 3 D charge trapping NAND flash devices with improved operation characteristics.
文摘This paper deals with the Gevreg-hypoellipticity for a class of totally characteristic operators with the elliptic condition and the discrete boundary spectrum condition respectively.
文摘The Low Frequency Synchromotor Drive Mine Hoist System fed by the cycloinverter has good features from the technological and economical point of view. According to the erating char acteristic of the mine hoist system, an advanced analysis is given to the construction, the operating characteristics and the harmonics of the magnetomotive force of the synchromotor fed by the cy cloinverter, and the beneficial suggestions are also given in this paper.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No 2018MS004
文摘We present a conceptual configuration of a high-temperature superconducting（HTS）magnet made from REBCO（Re=Rare Earth,B=Barium,C=Copper,O=Oxide）annular plates,called a Bitter-like HTS magnet,which can operate in persistent current mode without joint resistance and can be excited by a flux pump and without current leads and a persistent power supply.An REBCO annular magnet which can generate 1.5 T corresponding to the operating current density 80%of critical current density of the magnet at an operating temperature of65 K is conceptually designed.Then the thermal stability of the magnet is numerically simulated by Comsol software.Whein a piece of RBCO annular plate quenches,the maximum released energy is its stored energy because each REBCO annular plate in the Bitter-like magnet is in parallel.To calculate the stored energy in the REBCO annular plate,the inductance of every annular plate,including self-inductance and mutual inductance,is calculated.Compared with the minimum quench energy（MQE）and stored energy in one REBCO annular plate,the stored energy in one REBCO annular plate is always smaller than the MQE,and the REBCO annular plate will not be damaged even though the stored energy in the REBCO annular plate is fully released,which indicates that this 1.5 T Bitter-like magnet has the property of self-protection.
基金supported by Joint Fund for Equipment Preresearch and Aerospace Science and Technology (No. 6141B061203)。
文摘The common propellants used for electric thrusters, such as xenon and krypton, are rare, expensive,and difficult to acquire. Solid iodine attracts much attention with the advantages of low cost,extensive availability, low vapor pressure, and ionization potential. The performance of a lowpower iodine-fed Hall thruster matched with a xenon-fed cathode is investigated across a broad range of operation conditions. Regulation of the iodine vapor's mass flow rates is stably achieved by using a temperature control method of the iodine reservoir. The thrust measurements are finished utilizing a thrust target during the tests. Results show that thrust and anode-specific impulse increase approximately linearly with the increasing iodine mass flow rate.At the nominal power of 200 W class, iodine mass flow rates are 0.62 and 0.93 mg/s, thrusts are7.19 and 7.58 m N, anode specific impulses are 1184 and 826 s, anode efficiencies are 20.8%and 14.5%, and thrust to power ratios are 35.9 and 37.9 m N/k W under the conditions of 250 V,0.8 A and 200 V, 1.0 A, respectively. The operating characteristics of iodine-fed Hall thruster are analyzed in different states. Further work on the measurements of plasma characteristics and experimental optimization will be carried out.
基金supported by grants from Dongzhimen Hospital Fund of Special Talent(2018RC01)Beijing University of Chinese Medicine Fund of Project(2019-JYB-XJSJJ-025)
文摘BACKGROUND:The study aimed to evaluate the predictive role of interleukin-6(IL-6)and chronic obstructive pulmonary disease(COPD)assessment test(CAT)score in mechanical ventilation(MV)in COPD patients at the acute exacerbation stage in the emergency department(ED).METHODS:For a one-year period,among adult patients in the ED who met the criteria of acute exacerbation of COPD,158 who received MV within 48 hours after admission were compared to 294 who didn't require MV within the same period after admission.IL-6 level and CAT score were compared between the two groups.The predicted value of IL-6 and CAT score was assessed by logistic regression analysis and a receiver operating characteristic(ROC)curve.RESULTS:The IL-6 and CAT scores in the 158 MV patients were much higher than those without.IL-6 and CAT scores were independent predictors of MV within 48 hours using logistic regression analysis(IL-6:odds ratio[OR]1.053,95%confidence interval[CI]1.039–1.067,P<0.001;CAT score:OR 1.122,95%CI 1.086–1.159,P<0.001).The combination of IL-6 and CAT scores(area under ROC curve[AUC]0.826,95%CI 0.786–0.866,P<0.001)improved the accuracy of predicting MV within 48 hours when compared with IL-6(AUC 0.752,95%CI 0.703–0.800,P<0.001)and CAT scores alone(AUC 0.739,95%CI 0.692–0.786,P<0.001).The sensitivity and specificity were 69.6%,74.1%,75.32%and 63.6%,respectively.CONCLUSION:The combined of IL-6 and CAT scores is useful for evaluating the risk of COPD patients at acute exacerbation in ED,and can provide a predictive value for MV or not within 48 hours.
文摘Objective: Using receiver operating characteristics (ROC) curve to evaluate the value of pulse wave velocity (PWV) in the diagnosis of coronary heart disease (CHD). Methods: By using coronary angiography as golden diagnostic standard of CHD, 218 patients were divided into both CHD group (n=121) and non-CHD group (n = 97). All these patients received PWV test. The efficacy of PWV of each artery segments in the diagnosis of CHD was evaluated by ROC curve. The sensitivity and specificity were calculated with the golden diagnostic standard of CHD. Results:The PWV of right carotid to femoral artery (Rc-f), left carotid to femoral artery (Lc-f), right radial to carotid artery (Rc-r), left radial to carotid artery (Lc-r) in CHD group were significantly higher than that of non-CHD group (9. 31±1. 75 vs 7.60±1.59, P<0. 01; 9. 02±1.71 vs 7. 52±1.50, P<0. 01; 8. 69±1. 37 vs 8. 00±1. 27, P<0. 01; 8.52±1. 03 vs 8. 03±1. 2, P<0. 01 respectively). However, the PWV of both right and left femoral to ankle artery (Rf-a and Lf-a) had no significant differences between the two groups. We then compared the area under curve (AUC) of each ROC(AUCROC) of PWV of Rc-f, Lc-f Rc-r and Lc-r to evaluate their diagnostic efficacy for CHD. We found that AUCROC of Rc-f PWV was the biggest (AUCROC = 0. 818), at the peak point of its ROC curve, the PWV was 8. 32 m/s. PWV>8. 32 m/s of Rc-f could predict the presence of CHD with a sensitivity of 79% and specificity of 77%. Conclusion: The PWV of Rc-f, Lc-f, Rc-r, Lc-r are significantly higher in CHD group than that in non-CHD group, and PWV of Rc-f is the most accurate in the detection of CHD. The PWV>8. 32 m/s of RC-F is a valuable predictor of CHD.
文摘On the basis of strict mathematical description about Failure_Free Period Life Test (FFPLT), the statistical properties of the tests and optimal confidence limit of the parameter are discussed in detail and corresponding calculating formulae are found out.
文摘Understanding the drivers of biological invasions in landscapes is a major goal in invasion ecology.The control of biological invasions has increasingly become critical in the past few decades because invasive species are thought to be a major threat to endemism.In this study,by examining the key variables that influence Acacia mearnsii,we sought to understand its potential invasion in eastern Zimbabwe.We used the maximum entropy(MaxEnt)method against a set of environmental variables to predict the potential invasion front of A.mearnsii.Our study showed that the predictor variables,i.e.,aspect,elevation,distance from streams,soil type and distance from the nearest A.mearnsii plantation adequately explained(training AUC=0.96 and test AUC=0.93)variability in the spatial distribution of invading A.mearnsii.The front of invasion by A.mearnsii seemed also to occur next to existing A.mearnsii plantations.Results from our study could be useful in identifying priority areas that could be targeted for controlling the spread of A.mearnsii in Zimbabwe and other areas under threat from A.mearnsii invasion.We recommend that the plantation owners pay for the control of A.mearnsii invasion about their plantations.
基金supported by Clinical Scientific Research Fund of Zhejiang Medical Association(2021ZYC-A73)。
文摘BACKGROUND:Spontaneous isolated superior mesenteric artery(SMA)dissection(SISMAD)is a rare cause of abdominal pain.The aim of the study is to investigate the role of a new parameter,the ratio of the SMA diameter to the superior mesenteric vein(SMV)diameter(SMA/SMV)based on non-enhanced computed tomography(CT),in the early diagnosis of SISMAD.METHODS:In a registry study from December 2013 to June 2021,97 abdominal pain SISMAD patients(SISMAD group)admitted to our hospital were enrolled.Meanwhile,the matched sex and age abdominal pain non-SISMAD patients at 1:2 were collected in reverse chronological order as the control group.Student’s t-test,Wilcoxon rank-sum test,and Chi-square test were used to compare differences between the SISMAD and control groups.Med Calc was used to generate receiver operating characteristic(ROC)curve.RESULTS:A total of 291 abdominal pain patients,including 97 SISMAD patients and 194 nonSISMAD patients,were included in the current study.The maximum SMA diameter,perivascular exudation,and SMA/SMV based on non-enhanced CT were significant between the two groups(all P<0.05).ROC curves showed that for the maximum SMA diameter,the area under the curve(AUC),cut-off,sensitivity,and specificity were 0.926,9.80,93.8%,and 79.4%,respectively.For SMA/SMV,its AUC,cut-off,sensitivity,and specificity were 0.956,0.83,88.7%,and 92.3%,respectively.The diagnostic efficiency of SMA/SMV was better than that of the maximum SMA diameter(P<0.05).The combined parameters of SMA/SMV and maximum SMA diameter had the best diagnostic efficiency(AUC=0.970).CONCLUSION:SMA/SMV may be a potential marker for SISMAD.
文摘Objective： To assess the value of MR spectroscopy （MRS） in the diagnosis of prostate cancer by meta-analysis. Methods： Prospective studies were selected from the MEDLINE, Ovid, Embase databases, Springer, Elsevier, China National Knowledge Infrastructure. According to the suggestion, results were determined by the ratio of （Cho＋Cr）/Cit. If this ratio was less than 0.75, negative result was respectively determined, and the definitive tumor was diagnosed as this threshold. According to the assessment standard of Evidence-based Medicine, English and Chinese literature in Grade A and B on MRS imaging was included. According to homogeneity test, different effect models were chosen to calculate different pooled weighted values of sensitivity, specificity and the corresponding 95% confidence intervals （95% CI）. Summary receiver operating characteristic （SROC） curves were used to assess the results. Funnel plot was used to analyze publication bias. Results： According to the assessment standard of Evidence-based Medicine, only 5 papers in Grade B were included in this research. The pooled weighted sensitivity and its 95% confidence interval is 82% （73%, 89%） and the pooled weighted sensitivity and its 95% confidence interval is 68% （58%, 76%）. The AUC （area under curve） is 83.40%. An asymmetric funnel plot suggested two missing studies leading to publication bias. Conclusion： If the ratio of （Cho＋Cr）/Cit is regarded as the diagnostic criteria in detecting prostate cancer by MRS, meta-analysis suggests this method has a better diagnostic value to detect the malignant prostate mass but the sensitivity needs to be improved. We hope to support a method and requirement about diagnostic test. Performing perspective register and improving quality of study design is the only way to reduce the bias and get real information of disease.
