Assume that L is a non-negative self-adjoint operator on L^(2)(ℝ^(n))with its heat kernels satisfying the so-called Gaussian upper bound estimate and that X is a ball quasi-Banach function space onℝ^(n) satisfying som...Assume that L is a non-negative self-adjoint operator on L^(2)(ℝ^(n))with its heat kernels satisfying the so-called Gaussian upper bound estimate and that X is a ball quasi-Banach function space onℝ^(n) satisfying some mild assumptions.Let HX,L(ℝ^(n))be the Hardy space associated with both X and L,which is defined by the Lusin area function related to the semigroup generated by L.In this article,the authors establish various maximal function characterizations of the Hardy space HX,L(ℝ^(n))and then apply these characterizations to obtain the solvability of the related Cauchy problem.These results have a wide range of generality and,in particular,the specific spaces X to which these results can be applied include the weighted space,the variable space,the mixed-norm space,the Orlicz space,the Orlicz-slice space,and the Morrey space.Moreover,the obtained maximal function characterizations of the mixed-norm Hardy space,the Orlicz-slice Hardy space,and the Morrey-Hardy space associated with L are completely new.展开更多
Consider a pseudo-differential operator T_(a)f(x)=∫_(R^(n))e^(ix,ζ)a(x,ζ)f(ζ)dζwhere the symbol a is in the rough Hormander class L^(∞)S_(ρ)^(m)with m∈R andρ∈[0,1].In this note,when 1≤p≤2,if n(ρ-1)/p and ...Consider a pseudo-differential operator T_(a)f(x)=∫_(R^(n))e^(ix,ζ)a(x,ζ)f(ζ)dζwhere the symbol a is in the rough Hormander class L^(∞)S_(ρ)^(m)with m∈R andρ∈[0,1].In this note,when 1≤p≤2,if n(ρ-1)/p and a∈L^(∞)S_(ρ)^(m),then for any f∈S(R^(n))and x∈R^(n),we prove that M(T_(a)f)(x)≤C(M(|f|^(p))(x))^(1/p) where M is the Hardy-Littlewood maximal operator.Our theorem improves the known results and the bound on m is sharp,in the sense that n(ρ-1)/p can not be replaced by a larger constant.展开更多
It is common for datasets to contain both categorical and continuous variables. However, many feature screening methods designed for high-dimensional classification assume that the variables are continuous. This limit...It is common for datasets to contain both categorical and continuous variables. However, many feature screening methods designed for high-dimensional classification assume that the variables are continuous. This limits the applicability of existing methods in handling this complex scenario. To address this issue, we propose a model-free feature screening approach for ultra-high-dimensional multi-classification that can handle both categorical and continuous variables. Our proposed feature screening method utilizes the Maximal Information Coefficient to assess the predictive power of the variables. By satisfying certain regularity conditions, we have proven that our screening procedure possesses the sure screening property and ranking consistency properties. To validate the effectiveness of our approach, we conduct simulation studies and provide real data analysis examples to demonstrate its performance in finite samples. In summary, our proposed method offers a solution for effectively screening features in ultra-high-dimensional datasets with a mixture of categorical and continuous covariates.展开更多
In this paper, we get W 1,p(Rn)-boundedness for tangential maximal func- tion and nontangential maximal function , which improves J.Kinnunen, P.Lindqvist and Tananka’s results.
AIM To assess for passive expansion of sub-maximally dilated transjugular intrahepatic portosystemic shunts(TIPS) and compare outcomes with maximally dilated TIPS.METHODS Polytetrafluoroethylene covered TIPS(Viatorr) ...AIM To assess for passive expansion of sub-maximally dilated transjugular intrahepatic portosystemic shunts(TIPS) and compare outcomes with maximally dilated TIPS.METHODS Polytetrafluoroethylene covered TIPS(Viatorr) from July 2002 to December 2013 were retrospectively reviewed at two hospitals in a single institution. Two hundred and thirty patients had TIPS maximally dilated to 10 mm(m TIPS), while 43 patients who were at increased risk for hepatic encephalopathy(HE), based on clinical evaluation or low pre-TIPS portosystemic gradient(PSG), had 10 mm TIPS sub-maximally dilated to 8 mm(sm TIPS). Group characteristics(age, gender, Model for End-Stage Liver Disease score, post-TIPS PSG and clinical outcomes were compared between groups, including clinical success(ascites or varices), primary patency,primary assisted patency, and severe post-TIPS HE. A subset of fourteen patients with sm TIPS underwent follow-up computed tomography imaging after TIPS creation, and were grouped based on time of imaging(< 6 mo and > 6 mo). Change in diameter and crosssectional area were measured with 3D imaging software to evaluate for passive expansion.RESULTS Patient characteristics were similar between the sm TIPS and m TIPS groups, except for pre-TIPS portosystemic gradient, which was lower in the sm TIPS group(19.4 mm Hg ± 6.8 vs 22.4 mm Hg ± 7.1, P = 0.01). Primary patency and primary assisted patency between sm TIPS and m TIPS was not significantly different(P = 0.64 and 0.55, respectively). Four of the 55 patients(7%) with sm TIPS required TIPS reduction for severe refractory HE, while this occurred in 6 of the 218 patients(3%) with m TIPS(P = 0.12). For the 14 patients with follow-up computed tomography(CT) imaging, the median imaging follow-up was 373 d. There was an increase in median TIPS diameter, median percent diameter change, median area, and median percent area change in patients with CT follow-up greater than 6 mo after TIPS placement compared to follow-up within 6 mo(8.45 mm, 5.58%, 56.04 mm^2, and 11.48%, respectively, P = 0.01).CONCLUSION Passive expansion of sm TIPS does occur but clinical outcomes of sm TIPS and m TIPS were similar. Sub-maximal dilation can prevent complications related to overshunting in select patients.展开更多
BACKGROUND It is important to differentiate benign and malignant focal liver lesions(FLLs)accurately.Despite the wide use and acceptance of shear wave elastography(SWE),its value for assessing the elasticity of FLLs a...BACKGROUND It is important to differentiate benign and malignant focal liver lesions(FLLs)accurately.Despite the wide use and acceptance of shear wave elastography(SWE),its value for assessing the elasticity of FLLs and differentiating benign and malignant FLLs is still investigational.Previous studies of SWE for FLLs used mean elasticity as the parameter to reflect the stiffness of FLLs.Considering the inhomogeneity of tumor stiffness,maximal elasticity(Emax)might be the suitable parameter to reflect the stiffness of FLLs and to differentiate malignant FLLs from benign ones.AIM To explore the value of SWE with Emax in differential diagnosis of solid FLLs.METHODS We included 104 solid FLLs in 95 patients and 50 healthy volunteers.All the subjects were examined using conventional ultrasound(US)and virtual touch tissue quantification(VTQ)imaging.A diagnosis of benign or malignant FLL was made using conventional US.Ten VTQ values were acquired after 10 consecutive measurements for each FLL and each normal liver,and the largest value was recorded as Emax.RESULTS There were 56 cases of malignant FLLs and 48 cases of benign FLLs in this study.Emax of malignant FLLs(3.29±0.88 m/s)was significantly higher than that of benign FLLs(1.30±0.46 m/s,P<0.01)and that of livers in healthy volunteers(1.15±0.17 m/s,P<0.01).The cut-off point of Emax was 1.945,and the area under the curve was 0.978.The sensitivity and specificity of Emax were 92.9%and 91.7%,respectively,higher(but not significantly)than those of conventional US(80.4%for sensitivity and 81.3%for specificity).Combined diagnosis of conventional US and Emax using parallel testing improved the sensitivity to 100%with specificity of 75%.CONCLUSION SWE is a convenient and easy method to obtain accurate stiffness information of solid FLLs.Emax is useful for differential diagnosis of FLLs,especially in combination with conventional US.展开更多
Current research on robotic dexterous hands mainly focuses on designing new finger and palm structures,as well as developing smarter control algorithms.Although the dimensional synthesis of dexterous hands with tradit...Current research on robotic dexterous hands mainly focuses on designing new finger and palm structures,as well as developing smarter control algorithms.Although the dimensional synthesis of dexterous hands with traditional rigid palms has been carried out,research on the dimensional synthesis of dexterous hands with metamorphic palms remains insufficient.This study investigated the dimensional synthesis of a palm of a novel metamorphic multi-fingered hand,and explored the geometric design for maximizing the precision manipulation workspace.Different indexes were used to value the workspace of the metamorphic hand,and the best proportions between the five links of the palm to obtain the optimal workspace of the metamorphic hand were explored.Based on the fixed total length of the palm member,four nondimensional design parameters that determine the size of the palm were introduced;through the discretization method,the influence of the four design parameters on the workspace of the metamorphic hand with full-actuated fingers and under-actuated fingers was analyzed.Based on the analysis of the metamorphic multi-fingered hand,the symmetrical structure of the palm was designed,resulting in the largest workspace of the multi-fingered hand,and proved that the metamorphic palm has a massive upgrade for the workspace of underactuated fingers.This research contributed to the dimensional synthesis of metamorphic dexterous hands,with practical significance for the design and optimization of novel metamorphic hands.展开更多
Let p ∈(n/(n + l), 1]. The authors investigate the (Hbp(Rn), Lp(Rn)-type and (Hbp,∞(Rn), Lp,∞ (Rn)-type continuities for the maximal operators associated with the commutators of Bochner-mesz operators with BMO(Rn )...Let p ∈(n/(n + l), 1]. The authors investigate the (Hbp(Rn), Lp(Rn)-type and (Hbp,∞(Rn), Lp,∞ (Rn)-type continuities for the maximal operators associated with the commutators of Bochner-mesz operators with BMO(Rn ) functions, where Hbp(Rn ) and Hpb∞(Rn) are, respectively, the variants of the standard Hardy spaces and the standard weak Hardy spaces.展开更多
BACKGROUND Preoperative pulmonary function plays an important role in selecting surgical candidates and assessing postoperative complications.Reduced pulmonary function is associated with poor survival in several canc...BACKGROUND Preoperative pulmonary function plays an important role in selecting surgical candidates and assessing postoperative complications.Reduced pulmonary function is associated with poor survival in several cancers,but the prognostic value of preoperative pulmonary function in esophageal squamous cell carcinoma(ESCC)is unclear.Nutritional and systemic inflammation parameters are vital to cancer survival,and the combination of these parameters improves the prognostic value.The hemoglobin,albumin,lymphocytes and platelets(HALP)score is a novel prognostic indicator to reflect the nutritional and inflammation status,but the clinical effects of the HALP score combined with maximal voluntary ventilation(MVV),an important parameter of pulmonary function,have not been well studied in ESCC.AIM To investigate the prognostic value of MVV and HALP score for assessing postoperative survival of ESCC patients.METHODS Data form 834 ESCC patients who underwent radical esophagectomy with R0 resection were collected and retrospectively analyzed.Preoperative MVV and HALP data were retrieved from medical archives.The HALP score was calculated by the formula:Hemoglobin(g/L)×albumin(g/L)×lymphocytes(/L)/platelets(/L).The optimal cut-off values of MVV and HALP score were calculated by the receiver operating characteristic curve analysis.The Kaplan-Meier method with log-rank test was used to draw the survival curves for the variables tested.Multivariate Cox proportional hazard regression models were used to analyze the independent prognostic factors for overall survival.RESULTS MVV was significantly associated with gender(P<0.001),age at diagnosis(P<0.001),smoking history(P<0.001),drinking history(P<0.001),tumor length(P=0.013),tumor location(P=0.037)and treatment type(P=0.001).The HALP score was notably associated with gender(P<0.001),age at diagnosis(P=0.035),tumor length(P<0.001)and invasion depth(P=0.001).Univariate Cox regression analysis showed that low MVV and low HALP score were associated with worse overall survival(all P<0.001).Multivariate analysis showed that low MVV and the HALP score were both independent risk factors for overall survival(all P<0.001).The combination of MVV and HALP score improved the prediction performance for overall survival than tumor-node-metastasis.Also,low combination of MVV and HALP score was an independent risk factor for poor overall survival(P<0.001).CONCLUSION MVV,HALP score and their combination are simple and promising clinical markers to predict overall survival of ESCC patients.展开更多
In this article, some necessary and sufficient conditions are shown in order that weighted inequality of the form ■holds a.e. for uniformly integrable martingales f =(f_n)n≥0 with some constant C > 0,where Φ_1,...In this article, some necessary and sufficient conditions are shown in order that weighted inequality of the form ■holds a.e. for uniformly integrable martingales f =(f_n)n≥0 with some constant C > 0,where Φ_1,Φ_2 are Young functions, w_i(i = 1,2,3, 4) are weights, f~* =sup n≥0 |f_n| and f_∞=lim n→∞ f_n a.e. As an application, two-weight weak type maximal inequalities of martingales are considered, and particularly a new equivalence condition is presented.展开更多
A proximal iterative algorithm for the mulitivalue operator equation 0 ∈ T(x) is presented, where T is a maximal monotone operator. It is an improvement of the proximal point algorithm as well know. The convergence o...A proximal iterative algorithm for the mulitivalue operator equation 0 ∈ T(x) is presented, where T is a maximal monotone operator. It is an improvement of the proximal point algorithm as well know. The convergence of the algorithm is discussed and all example is given.展开更多
The main aim of this article is to prove that the maximal operator σ_κ~*of the Marcinkiewicz-Fejér means of the two-dimensional Fourier series with respect to WalshKaczmarz system is bounded from the Hardy spac...The main aim of this article is to prove that the maximal operator σ_κ~*of the Marcinkiewicz-Fejér means of the two-dimensional Fourier series with respect to WalshKaczmarz system is bounded from the Hardy space H_(2/3)to the space weak-L_(2/3).展开更多
Given a maximal subgroup M of a group G, a θ*-completion C of M is called an s*-completion if either C = G or there exists a subgroup D of G which is not a θ*-completion of M such that D contains C as a maximal subg...Given a maximal subgroup M of a group G, a θ*-completion C of M is called an s*-completion if either C = G or there exists a subgroup D of G which is not a θ*-completion of M such that D contains C as a maximal subgroup. In this paper, we obtain several results on s*-completions which imply G to be solvable or supersolvable.展开更多
Let and A be the generator of an -times resolvent family on a Banach space X. It is shown that the fractional Cauchy problem has maximal regularity on if and only if is of bounded semivariation on .
BACKGROUND Vascular endothelial dysfunction is an underlying pathophysiological feature of chronic heart failure(CHF).Patients with CHF are characterized by impaired vasodilation and inflammation of the vascular endot...BACKGROUND Vascular endothelial dysfunction is an underlying pathophysiological feature of chronic heart failure(CHF).Patients with CHF are characterized by impaired vasodilation and inflammation of the vascular endothelium.They also have low levels of endothelial progenitor cells(EPCs).EPCs are bone marrow derived cells involved in endothelium regeneration,homeostasis,and neovascularization.Exercise has been shown to improve vasodilation and stimulate the mobilization of EPCs in healthy people and patients with cardiovascular comorbidities.However,the effects of exercise on EPCs in different stages of CHF remain under investigation.AIM To evaluate the effect of a symptom-limited maximal cardiopulmonary exercise testing(CPET)on EPCs in CHF patients of different severity.METHODS Forty-nine consecutive patients(41 males)with stable CHF[mean age(years):56±10,ejection fraction(EF,%):32±8,peak oxygen uptake(VO2,mL/kg/min):18.1±4.4]underwent a CPET on a cycle ergometer.Venous blood was sampled before and after CPET.Five circulating endothelial populations were quantified by flow cytometry:Three subgroups of EPCs[CD34+/CD45-/CD133+,CD34+/CD45-/CD133+/VEGFR2 and CD34+/CD133+/vascular endothelial growth factor receptor 2(VEGFR2)]and two subgroups of circulating endothelial cells(CD34+/CD45-/CD133-and CD34+/CD45-/CD133-/VEGFR2).Patients were divided in two groups of severity according to the median value of peak VO2(18.0 mL/kg/min),predicted peak VO2(65.5%),ventilation/carbon dioxide output slope(32.5)and EF(reduced and mid-ranged EF).EPCs values are expressed as median(25th-75th percentiles)in cells/106 enucleated cells.RESULTS Patients with lower peak VO2 increased the mobilization of CD34+/CD45-/CD133+[pre CPET:60(25-76)vs post CPET:90(70-103)cells/106 enucleated cells,P<0.001],CD34+/CD45-/CD133+/VEGFR2[pre CPET:1(1-4)vs post CPET:5(3-8)cells/106 enucleated cells,P<0.001],CD34+/CD45-/CD133-[pre CPET:186(141-361)vs post CPET:488(247-658)cells/106 enucleated cells,P<0.001]and CD34+/CD45-/CD133-/VEGFR2[pre CPET:2(1-2)vs post CPET:3(2-5)cells/106 enucleated cells,P<0.001],while patients with higher VO2 increased the mobilization of CD34+/CD45-/CD133+[pre CPET:42(19-73)vs post CPET:90(39-118)cells/106 enucleated cells,P<0.001],CD34+/CD45-/CD133+/VEGFR2[pre CPET:2(1-3)vs post CPET:6(3-9)cells/106 enucleated cells,P<0.001],CD34+/CD133+/VEGFR2[pre CPET:10(7-18)vs post CPET:14(10-19)cells/106 enucleated cells,P<0.01],CD34+/CD45-/CD133-[pre CPET:218(158-247)vs post CPET:311(254-569)cells/106 enucleated cells,P<0.001]and CD34+/CD45-/CD133-/VEGFR2[pre CPET:1(1-2)vs post CPET:4(2-6)cells/106 enucleated cells,P<0.001].A similar increase in the mobilization of at least four out of five cellular populations was observed after maximal exercise within each severity group regarding predicted peak,ventilation/carbon dioxide output slope and EF as well(P<0.05).However,there were no statistically significant differences in the mobilization of endothelial cellular populations between severity groups in each comparison(P>0.05).CONCLUSION Our study has shown an increased EPCs and circulating endothelial cells mobilization after maximal exercise in CHF patients,but this increase was not associated with syndrome severity.Further investigation,however,is needed.展开更多
Let M f be the Kakeya maximal function in d-dimensional Euclidean space, with same base consisting of cylinders of eccentricity N. The inequality shoum for a base satisfying a direction condition, where ?and c are con...Let M f be the Kakeya maximal function in d-dimensional Euclidean space, with same base consisting of cylinders of eccentricity N. The inequality shoum for a base satisfying a direction condition, where ?and c are constants depending only on d.展开更多
The purpose of this paper is to prove that on the Riemannian symmetric space of rank-one, and on the complex symmetric space, the maximal functions associated to the heat kernel and to the Poisson kernel are weak (1—...The purpose of this paper is to prove that on the Riemannian symmetric space of rank-one, and on the complex symmetric space, the maximal functions associated to the heat kernel and to the Poisson kernel are weak (1—1) type bounded,展开更多
In this note the authors give the weighted Lp-boundedness for a class of maximal singular integral operators with rough kernel. The result in this note is an improvement and extension of the result obtained by Chen an...In this note the authors give the weighted Lp-boundedness for a class of maximal singular integral operators with rough kernel. The result in this note is an improvement and extension of the result obtained by Chen and Lin in 1990.展开更多
Two existence theorems of maximal elements of condensing preference maps in locallyconvex Hausdorff spaces are proved which generalize the recent results of Mehta.One ofthem positively answers the Open problem mention...Two existence theorems of maximal elements of condensing preference maps in locallyconvex Hausdorff spaces are proved which generalize the recent results of Mehta.One ofthem positively answers the Open problem mentioned by Mehta.展开更多
基金supported by the National Key Research and Development Program of China(2020YFA0712900)the National Natural Science Foundation of China(12371093,12071197,12122102 and 12071431)+2 种基金the Key Project of Gansu Provincial National Science Foundation(23JRRA1022)the Fundamental Research Funds for the Central Universities(2233300008 and lzujbky-2021-ey18)the Innovative Groups of Basic Research in Gansu Province(22JR5RA391).
文摘Assume that L is a non-negative self-adjoint operator on L^(2)(ℝ^(n))with its heat kernels satisfying the so-called Gaussian upper bound estimate and that X is a ball quasi-Banach function space onℝ^(n) satisfying some mild assumptions.Let HX,L(ℝ^(n))be the Hardy space associated with both X and L,which is defined by the Lusin area function related to the semigroup generated by L.In this article,the authors establish various maximal function characterizations of the Hardy space HX,L(ℝ^(n))and then apply these characterizations to obtain the solvability of the related Cauchy problem.These results have a wide range of generality and,in particular,the specific spaces X to which these results can be applied include the weighted space,the variable space,the mixed-norm space,the Orlicz space,the Orlicz-slice space,and the Morrey space.Moreover,the obtained maximal function characterizations of the mixed-norm Hardy space,the Orlicz-slice Hardy space,and the Morrey-Hardy space associated with L are completely new.
基金Supported by the National Natural Science Foundation of China(11871436,12071437)。
文摘Consider a pseudo-differential operator T_(a)f(x)=∫_(R^(n))e^(ix,ζ)a(x,ζ)f(ζ)dζwhere the symbol a is in the rough Hormander class L^(∞)S_(ρ)^(m)with m∈R andρ∈[0,1].In this note,when 1≤p≤2,if n(ρ-1)/p and a∈L^(∞)S_(ρ)^(m),then for any f∈S(R^(n))and x∈R^(n),we prove that M(T_(a)f)(x)≤C(M(|f|^(p))(x))^(1/p) where M is the Hardy-Littlewood maximal operator.Our theorem improves the known results and the bound on m is sharp,in the sense that n(ρ-1)/p can not be replaced by a larger constant.
文摘It is common for datasets to contain both categorical and continuous variables. However, many feature screening methods designed for high-dimensional classification assume that the variables are continuous. This limits the applicability of existing methods in handling this complex scenario. To address this issue, we propose a model-free feature screening approach for ultra-high-dimensional multi-classification that can handle both categorical and continuous variables. Our proposed feature screening method utilizes the Maximal Information Coefficient to assess the predictive power of the variables. By satisfying certain regularity conditions, we have proven that our screening procedure possesses the sure screening property and ranking consistency properties. To validate the effectiveness of our approach, we conduct simulation studies and provide real data analysis examples to demonstrate its performance in finite samples. In summary, our proposed method offers a solution for effectively screening features in ultra-high-dimensional datasets with a mixture of categorical and continuous covariates.
基金Supported by the key Academic Discipline of Zhejiang Province of China under Grant No.2005the Zhejiang Provincial Natural Science Foundation of China
文摘In this paper, we get W 1,p(Rn)-boundedness for tangential maximal func- tion and nontangential maximal function , which improves J.Kinnunen, P.Lindqvist and Tananka’s results.
文摘AIM To assess for passive expansion of sub-maximally dilated transjugular intrahepatic portosystemic shunts(TIPS) and compare outcomes with maximally dilated TIPS.METHODS Polytetrafluoroethylene covered TIPS(Viatorr) from July 2002 to December 2013 were retrospectively reviewed at two hospitals in a single institution. Two hundred and thirty patients had TIPS maximally dilated to 10 mm(m TIPS), while 43 patients who were at increased risk for hepatic encephalopathy(HE), based on clinical evaluation or low pre-TIPS portosystemic gradient(PSG), had 10 mm TIPS sub-maximally dilated to 8 mm(sm TIPS). Group characteristics(age, gender, Model for End-Stage Liver Disease score, post-TIPS PSG and clinical outcomes were compared between groups, including clinical success(ascites or varices), primary patency,primary assisted patency, and severe post-TIPS HE. A subset of fourteen patients with sm TIPS underwent follow-up computed tomography imaging after TIPS creation, and were grouped based on time of imaging(< 6 mo and > 6 mo). Change in diameter and crosssectional area were measured with 3D imaging software to evaluate for passive expansion.RESULTS Patient characteristics were similar between the sm TIPS and m TIPS groups, except for pre-TIPS portosystemic gradient, which was lower in the sm TIPS group(19.4 mm Hg ± 6.8 vs 22.4 mm Hg ± 7.1, P = 0.01). Primary patency and primary assisted patency between sm TIPS and m TIPS was not significantly different(P = 0.64 and 0.55, respectively). Four of the 55 patients(7%) with sm TIPS required TIPS reduction for severe refractory HE, while this occurred in 6 of the 218 patients(3%) with m TIPS(P = 0.12). For the 14 patients with follow-up computed tomography(CT) imaging, the median imaging follow-up was 373 d. There was an increase in median TIPS diameter, median percent diameter change, median area, and median percent area change in patients with CT follow-up greater than 6 mo after TIPS placement compared to follow-up within 6 mo(8.45 mm, 5.58%, 56.04 mm^2, and 11.48%, respectively, P = 0.01).CONCLUSION Passive expansion of sm TIPS does occur but clinical outcomes of sm TIPS and m TIPS were similar. Sub-maximal dilation can prevent complications related to overshunting in select patients.
基金Natural Science Foundation of Shanghai of China,No.19ZR1441500.
文摘BACKGROUND It is important to differentiate benign and malignant focal liver lesions(FLLs)accurately.Despite the wide use and acceptance of shear wave elastography(SWE),its value for assessing the elasticity of FLLs and differentiating benign and malignant FLLs is still investigational.Previous studies of SWE for FLLs used mean elasticity as the parameter to reflect the stiffness of FLLs.Considering the inhomogeneity of tumor stiffness,maximal elasticity(Emax)might be the suitable parameter to reflect the stiffness of FLLs and to differentiate malignant FLLs from benign ones.AIM To explore the value of SWE with Emax in differential diagnosis of solid FLLs.METHODS We included 104 solid FLLs in 95 patients and 50 healthy volunteers.All the subjects were examined using conventional ultrasound(US)and virtual touch tissue quantification(VTQ)imaging.A diagnosis of benign or malignant FLL was made using conventional US.Ten VTQ values were acquired after 10 consecutive measurements for each FLL and each normal liver,and the largest value was recorded as Emax.RESULTS There were 56 cases of malignant FLLs and 48 cases of benign FLLs in this study.Emax of malignant FLLs(3.29±0.88 m/s)was significantly higher than that of benign FLLs(1.30±0.46 m/s,P<0.01)and that of livers in healthy volunteers(1.15±0.17 m/s,P<0.01).The cut-off point of Emax was 1.945,and the area under the curve was 0.978.The sensitivity and specificity of Emax were 92.9%and 91.7%,respectively,higher(but not significantly)than those of conventional US(80.4%for sensitivity and 81.3%for specificity).Combined diagnosis of conventional US and Emax using parallel testing improved the sensitivity to 100%with specificity of 75%.CONCLUSION SWE is a convenient and easy method to obtain accurate stiffness information of solid FLLs.Emax is useful for differential diagnosis of FLLs,especially in combination with conventional US.
基金Supported by National Natural Science Foundation of China(Grant No.51535008).
文摘Current research on robotic dexterous hands mainly focuses on designing new finger and palm structures,as well as developing smarter control algorithms.Although the dimensional synthesis of dexterous hands with traditional rigid palms has been carried out,research on the dimensional synthesis of dexterous hands with metamorphic palms remains insufficient.This study investigated the dimensional synthesis of a palm of a novel metamorphic multi-fingered hand,and explored the geometric design for maximizing the precision manipulation workspace.Different indexes were used to value the workspace of the metamorphic hand,and the best proportions between the five links of the palm to obtain the optimal workspace of the metamorphic hand were explored.Based on the fixed total length of the palm member,four nondimensional design parameters that determine the size of the palm were introduced;through the discretization method,the influence of the four design parameters on the workspace of the metamorphic hand with full-actuated fingers and under-actuated fingers was analyzed.Based on the analysis of the metamorphic multi-fingered hand,the symmetrical structure of the palm was designed,resulting in the largest workspace of the multi-fingered hand,and proved that the metamorphic palm has a massive upgrade for the workspace of underactuated fingers.This research contributed to the dimensional synthesis of metamorphic dexterous hands,with practical significance for the design and optimization of novel metamorphic hands.
基金Tang Lin and Yang Dachun are supported in part by the NNSF and the SEDF of China.
文摘Let p ∈(n/(n + l), 1]. The authors investigate the (Hbp(Rn), Lp(Rn)-type and (Hbp,∞(Rn), Lp,∞ (Rn)-type continuities for the maximal operators associated with the commutators of Bochner-mesz operators with BMO(Rn ) functions, where Hbp(Rn ) and Hpb∞(Rn) are, respectively, the variants of the standard Hardy spaces and the standard weak Hardy spaces.
基金Supported by National Natural Science Foundation of China,No.U1301227,No.81872032 and No.U1804262Doctoral Team Foundation of the First Affiliated Hospital of Zhengzhou University,No.2016-BSTDJJ-03.
文摘BACKGROUND Preoperative pulmonary function plays an important role in selecting surgical candidates and assessing postoperative complications.Reduced pulmonary function is associated with poor survival in several cancers,but the prognostic value of preoperative pulmonary function in esophageal squamous cell carcinoma(ESCC)is unclear.Nutritional and systemic inflammation parameters are vital to cancer survival,and the combination of these parameters improves the prognostic value.The hemoglobin,albumin,lymphocytes and platelets(HALP)score is a novel prognostic indicator to reflect the nutritional and inflammation status,but the clinical effects of the HALP score combined with maximal voluntary ventilation(MVV),an important parameter of pulmonary function,have not been well studied in ESCC.AIM To investigate the prognostic value of MVV and HALP score for assessing postoperative survival of ESCC patients.METHODS Data form 834 ESCC patients who underwent radical esophagectomy with R0 resection were collected and retrospectively analyzed.Preoperative MVV and HALP data were retrieved from medical archives.The HALP score was calculated by the formula:Hemoglobin(g/L)×albumin(g/L)×lymphocytes(/L)/platelets(/L).The optimal cut-off values of MVV and HALP score were calculated by the receiver operating characteristic curve analysis.The Kaplan-Meier method with log-rank test was used to draw the survival curves for the variables tested.Multivariate Cox proportional hazard regression models were used to analyze the independent prognostic factors for overall survival.RESULTS MVV was significantly associated with gender(P<0.001),age at diagnosis(P<0.001),smoking history(P<0.001),drinking history(P<0.001),tumor length(P=0.013),tumor location(P=0.037)and treatment type(P=0.001).The HALP score was notably associated with gender(P<0.001),age at diagnosis(P=0.035),tumor length(P<0.001)and invasion depth(P=0.001).Univariate Cox regression analysis showed that low MVV and low HALP score were associated with worse overall survival(all P<0.001).Multivariate analysis showed that low MVV and the HALP score were both independent risk factors for overall survival(all P<0.001).The combination of MVV and HALP score improved the prediction performance for overall survival than tumor-node-metastasis.Also,low combination of MVV and HALP score was an independent risk factor for poor overall survival(P<0.001).CONCLUSION MVV,HALP score and their combination are simple and promising clinical markers to predict overall survival of ESCC patients.
基金Supported by the National Natural Science Foundation of China(11871195)
文摘In this article, some necessary and sufficient conditions are shown in order that weighted inequality of the form ■holds a.e. for uniformly integrable martingales f =(f_n)n≥0 with some constant C > 0,where Φ_1,Φ_2 are Young functions, w_i(i = 1,2,3, 4) are weights, f~* =sup n≥0 |f_n| and f_∞=lim n→∞ f_n a.e. As an application, two-weight weak type maximal inequalities of martingales are considered, and particularly a new equivalence condition is presented.
基金Supported by the National Natural Science Foundation of China
文摘A proximal iterative algorithm for the mulitivalue operator equation 0 ∈ T(x) is presented, where T is a maximal monotone operator. It is an improvement of the proximal point algorithm as well know. The convergence of the algorithm is discussed and all example is given.
基金supported by project TMOP-4.2.2.A-11/1/KONV-2012-0051,Shota Rustaveli National Science Foundation grant no.13/06(Geometry of function spaces,interpolation and embedding theorems)
文摘The main aim of this article is to prove that the maximal operator σ_κ~*of the Marcinkiewicz-Fejér means of the two-dimensional Fourier series with respect to WalshKaczmarz system is bounded from the Hardy space H_(2/3)to the space weak-L_(2/3).
文摘Given a maximal subgroup M of a group G, a θ*-completion C of M is called an s*-completion if either C = G or there exists a subgroup D of G which is not a θ*-completion of M such that D contains C as a maximal subgroup. In this paper, we obtain several results on s*-completions which imply G to be solvable or supersolvable.
文摘Let and A be the generator of an -times resolvent family on a Banach space X. It is shown that the fractional Cauchy problem has maximal regularity on if and only if is of bounded semivariation on .
基金Greece and the European Union(European Social Fund-ESF)through the Operational Programme“Human Resources Development,Education and Lifelong Learning”in the context of the project“Strengthening Human Resources Research Potential via Doctorate Research”(MIS-5000432),implemented by the State Scholarships Foundation(ΙΚΥ)the special account for research grants of the National and Kapodistrian University of Athens,Athens,Greece.
文摘BACKGROUND Vascular endothelial dysfunction is an underlying pathophysiological feature of chronic heart failure(CHF).Patients with CHF are characterized by impaired vasodilation and inflammation of the vascular endothelium.They also have low levels of endothelial progenitor cells(EPCs).EPCs are bone marrow derived cells involved in endothelium regeneration,homeostasis,and neovascularization.Exercise has been shown to improve vasodilation and stimulate the mobilization of EPCs in healthy people and patients with cardiovascular comorbidities.However,the effects of exercise on EPCs in different stages of CHF remain under investigation.AIM To evaluate the effect of a symptom-limited maximal cardiopulmonary exercise testing(CPET)on EPCs in CHF patients of different severity.METHODS Forty-nine consecutive patients(41 males)with stable CHF[mean age(years):56±10,ejection fraction(EF,%):32±8,peak oxygen uptake(VO2,mL/kg/min):18.1±4.4]underwent a CPET on a cycle ergometer.Venous blood was sampled before and after CPET.Five circulating endothelial populations were quantified by flow cytometry:Three subgroups of EPCs[CD34+/CD45-/CD133+,CD34+/CD45-/CD133+/VEGFR2 and CD34+/CD133+/vascular endothelial growth factor receptor 2(VEGFR2)]and two subgroups of circulating endothelial cells(CD34+/CD45-/CD133-and CD34+/CD45-/CD133-/VEGFR2).Patients were divided in two groups of severity according to the median value of peak VO2(18.0 mL/kg/min),predicted peak VO2(65.5%),ventilation/carbon dioxide output slope(32.5)and EF(reduced and mid-ranged EF).EPCs values are expressed as median(25th-75th percentiles)in cells/106 enucleated cells.RESULTS Patients with lower peak VO2 increased the mobilization of CD34+/CD45-/CD133+[pre CPET:60(25-76)vs post CPET:90(70-103)cells/106 enucleated cells,P<0.001],CD34+/CD45-/CD133+/VEGFR2[pre CPET:1(1-4)vs post CPET:5(3-8)cells/106 enucleated cells,P<0.001],CD34+/CD45-/CD133-[pre CPET:186(141-361)vs post CPET:488(247-658)cells/106 enucleated cells,P<0.001]and CD34+/CD45-/CD133-/VEGFR2[pre CPET:2(1-2)vs post CPET:3(2-5)cells/106 enucleated cells,P<0.001],while patients with higher VO2 increased the mobilization of CD34+/CD45-/CD133+[pre CPET:42(19-73)vs post CPET:90(39-118)cells/106 enucleated cells,P<0.001],CD34+/CD45-/CD133+/VEGFR2[pre CPET:2(1-3)vs post CPET:6(3-9)cells/106 enucleated cells,P<0.001],CD34+/CD133+/VEGFR2[pre CPET:10(7-18)vs post CPET:14(10-19)cells/106 enucleated cells,P<0.01],CD34+/CD45-/CD133-[pre CPET:218(158-247)vs post CPET:311(254-569)cells/106 enucleated cells,P<0.001]and CD34+/CD45-/CD133-/VEGFR2[pre CPET:1(1-2)vs post CPET:4(2-6)cells/106 enucleated cells,P<0.001].A similar increase in the mobilization of at least four out of five cellular populations was observed after maximal exercise within each severity group regarding predicted peak,ventilation/carbon dioxide output slope and EF as well(P<0.05).However,there were no statistically significant differences in the mobilization of endothelial cellular populations between severity groups in each comparison(P>0.05).CONCLUSION Our study has shown an increased EPCs and circulating endothelial cells mobilization after maximal exercise in CHF patients,but this increase was not associated with syndrome severity.Further investigation,however,is needed.
基金The author is partly supported by the Grants-in-Aid for Scientific Reseach,The Ministry of Educa-ion,Science and Culture,Japan.
文摘Let M f be the Kakeya maximal function in d-dimensional Euclidean space, with same base consisting of cylinders of eccentricity N. The inequality shoum for a base satisfying a direction condition, where ?and c are constants depending only on d.
文摘The purpose of this paper is to prove that on the Riemannian symmetric space of rank-one, and on the complex symmetric space, the maximal functions associated to the heat kernel and to the Poisson kernel are weak (1—1) type bounded,
文摘In this note the authors give the weighted Lp-boundedness for a class of maximal singular integral operators with rough kernel. The result in this note is an improvement and extension of the result obtained by Chen and Lin in 1990.
基金Project Supported by the National Natural Science Foundation of China
文摘Two existence theorems of maximal elements of condensing preference maps in locallyconvex Hausdorff spaces are proved which generalize the recent results of Mehta.One ofthem positively answers the Open problem mentioned by Mehta.
