Lie Symmetry and Conserved Quantity of Three-Order Lagrangian Equations for Non-conserved Mechanical System

Based on the infinitesimal and one parameter transformation, the problem of Lie symmetry of three-order Lagrangian equations has been studied. Under Lie transformation, the sufficient and necessary condition which keeps three-order Lagrangian equations to be unchanged and the invariant are obtained in this paper.

Three-order form invariance and conserved quantity

In this paper, the definition of three-order form invariance is given. Then the relation between the three-order form invariance and the three-order Lie symmetry is discussed and the sufficient and necessary condition of Lie symmetry, which comes from the three-order form invariance, is obtained. Finally a three-order Hojman conserved quantity is studied and an example is given to illustrate the application of the obtained results.

Noether Symmetry of Three-Order Lagrangian Equations

Based on the three-order Lagrangian equation, pseudo-Hamilton actoon I^＊ is defined and the three-order Hamilton＇s principle and the conditions are obtained in the paper. Then, the Noether symmetry about three-order Lagrangian equations is deduced. Finally, an example is given to illustrate the application of the result.

Dysfunctional attitudes,social support,negative life events,and depressive symptoms in Chinese adolescents:A moderated mediation model

BACKGROUND Depression is a prevalent psychological issue in adolescents that is significantly related to negative life events(NLEs)and dysfunctional attitudes.High levels of social support can significantly buffer NLEs’effect on depression.Currently,there is limited research on how social support moderates the relationship between NLEs,dysfunctional attitudes,and depression in adolescents in China.It is imperative to investigate this moderating effect to mitigate dysfunctional attitudes in adolescent undergoing depressive mood,ultimately enhancing their overall mental health.AIM To investigate the relationship and underlying mechanisms between specific dysfunctional attitudes,social support,and depression among Chinese adolescents.METHODS This is a cross-sectional study which selected five middle schools in Shandong Province for investigation in March 2022.Participants included 795 adolescents(49.87%male,mage=15.15,SD=1.84,age range=11-18 years old).All participants completed the Dysfunctional Attitude Scale,Adolescent Life Event Scale,Beck Depression Inventory,and Social Support Rating Scale.A moderated mediation model was conducted to examine the relationship between specific dysfunctional attitudes,social support,and depression.RESULTS Results indicated that NLEs affected depression through the mediating role of specific dysfunctional attitudes(autonomy attitudesβ=0.21;perfectionismβ=0.25).Moreover,social support was found to moderate the mediating effect between NLEs,specific dysfunctional attitudes,and depressive symptoms(autonomy attitudes b2=-0.08;perfectionism b2=-0.09).CONCLUSION Dysfunctional attitudes mediated and social support moderated the relationship between NLEs and depression.Social support can buffer depression symptoms among adolescents with autonomy attitudes and perfectionism.

Three-order pseudo-Hamilton canonical equationsReceived

Based on the three-order Lagrangian equations, Hamilton＇s function of acceleration H^＊ and generalized acceleration momentum P^＊α are defined, and pseudo-Hamilton canonical equations corresponding to three-order Lagrangian equations are obtained. The equations are similar to Hamilton＇s canonical equations of analytical mechanics in form.

Marital Status as a Moderator:Exploring the Relationship between Social Engagement and Depressive Symptoms in China’s Older Adult Population

Objective This study aims to explore the complex relationship between social engagement and depressive symptoms among older adults in China,focusing particularly on the moderating role of marital status.Methods This study used data from the latest Chinese Longitudinal Healthy Longevity Survey(CLHLS).The analysis used the latent class analysis to delineate personality clusters and hierarchical linear regression,supplemented by the PROCESS macro,to investigate the effects of social engagement and marital status on depressive symptoms.Results The analysis encompassed 7,789 respondents(mean age:82.53[s=11.20]years),with 54%female.The personality analysis categorized participants into four clusters,with the majority(77.60%)classified as Confident Idealists,who exhibited the lowest levels of depressive symptoms.Hierarchical linear regression analysis yielded several significant findings:Higher levels of social engagement were significantly associated with fewer depressive symptoms(t=-7.932,P<0.001,B=-0.463).Marital status was a significant factor;married individuals reported fewer depressive symptoms compared to their unmarried counterparts(t=-6.368,P<0.001,B=-0.750).There was a significant moderating effect of marital status on the relationship between social engagement and depressive symptoms(t=-2.092,P=0.037,B=-0.217).Conclusion This study demonstrates that,among Chinese older adults,both social engagement and marital status significantly influence depressive symptoms.Higher social engagement,particularly in other activities like doing household chores,gardening,reading newspapers or books,and playing cards or Mahjong,is associated with fewer depressive symptoms,especially among married individuals.

Moderating Effect of Perceived Threat of Breast Cancer on Relation between Knowledge and Breast Self Examination

Estimated at more than 2.2 million cases worldwide,most breast cancer cases and deaths from breast cancer occur in low and middle-income countries.In Cameroon,many studies have underlined the effect of knowledge of breast cancer on screening measures such as self-examination and,to a lesser extent,the perception of the threat of this disease.This research aims to assess according to the Health Belief Model(HBM),the moderating effect of perceived threat of breast cancer on the relation between knowledge and breast self-examination.A questionnaire survey was conducted among 517 Cameroonian women to assess their general knowledge about breast cancer(risk factors and screening measures),their level of the perceived threat of breast cancer through Perceived susceptibility and severity,and the prevalence of breast self-examination amongst them.A regression analysis using the Macro Process for moderation indicates the main effect of Perceived threat(b=0,29;t(517)=2,36;p=0,02)of breast cancer and knowledge(b=0,02;t(517)=4,29;p<0,001)on breast self-examination.Results also confirm that the perceived threat of breast cancer moderates the effect of knowledge on breast self-examination.While the low level of perceived threat highlights the effect of knowledge on breast self-examination(b=0,02;t(517)=3,49;p<0,001),the high level of perceived threat cancels that effect(b=0,01;t(517)=1,97;p=0,01).A woman who perceives severity and susceptibility to breast cancer is more inclined to perform breast self-examination.This result suggests the importance of taking into account,in a context where knowledge of breast cancer is limited,relevant factors of the health belief model in preventive measures against breast cancer in general and the practice of breast self-examination in particular.

The Mediating and Moderating Effects of Family Resilience on the Relationship between Individual Resilience and Depression in Patients with Breast Cancer

Objective:This study evaluated the effect of resilience on depression among patients with breast cancer from individual and familial perspectives by exploring the mediating and moderating effects of family resilience between individual resilience and depression.Methods:A questionnaire survey was conducted among 337 patients with breast cancer who were admitted to the Oncology Department of Jiangsu Province Hospital.The survey included demographic information,the Connor–Davidson Resilience Scale(CD-RISC),the Family Resilience Assessment Scale(FRAS),and the Chinese version of the Patient Health Questionnaire-9(PHQ-9)for Depression.The relationship among individual resilience,family resilience,and depression was analyzed using hierarchical regression and bootstrap test to assess the mediating and moderating effects of family resilience.Results:The depression scores were(13.50±5.16),the individual resilience scores were(48.62±17.50),and the family resilience scores were(105.98±24.35).Significant differences in depression scores were observed in terms of family monthly income,average weekly exercise before diagnosis,post-diagnosis interpersonal relationship quality,and overall sleep quality in the past month(p<0.05).Patients with lower individual resilience had significantly higher depression scores than those with higher resilience(F=24.314,p<0.001),and similarly,patients with lower family resilience had higher depression scores than those with higher family resilience(F=41.660,p<0.001).Individual resilience and family resilience were significantly negatively correlated with depression(r=-0.447 and-0.441,respectively,p<0.001).Hierarchical regression analysis and bootstrap test showed that family resilience(β=-0.310,p<0.001)had a partial mediating effect between individual resilience(β=-0.321,p<0.001)and depression.The indirect effect size was-0.038,the 95%CI was(-0.056,-0.020),and the direct effect ratio was 71.43%.The interaction of family resilience and individual resilience had a moderating effect on depression(B=0.166,p<0.001).Family resilience negatively moderated the relationship between individual resilience and depressive symptoms and enhanced the protective effect of individual resilience against depression with increasing family resilience.Conclusion:Family resilience has mediating and moderating effects between individual resilience and depression in patients with breast cancer.

Relation between Interparental Conflict and Non-Suicidal Self-Injury in Adolescents:Mediating Role of Alexithymia and Moderating Role of Resilience

Background:Adolescents frequently engage in Non-Suicidal Self-Injury(NSSI),with recent trends indicating an increase in this behavior.At the same time,Chinese adolescents have a higher incidence of NSSI than Western adolescents.Therefore,it is necessary to explore the relationship between interparental conflict and NSSI among adolescents within the context of Chinese families.Methods:The research sample comprised 755 senior high school students(46.62%male;age M=16.82,SD=0.94 years)who completed the Interparental Conflict Child Perception Scale(CPIC),Adolescent Self-Injury Behavior Questionnaire(ASHS),Toronto Alexithymia Scale-20(TAS-20),and Scale of Adolescent Resilience(RSCA).Results:Findings suggest that interparental conflict is a significant positive predictor of NSSI(r=0.22,p<0.01).Alexithymia mediates the relation between interparental conflict and NSSI(effect size=0.09,95%CI[0.05,0.13]).Additionally,resilience moderates both the direct relation(β=−0.08,p<0.05)and the latter half of the mediating pathway(β=−0.08,p<0.05)in the moderated mediation model.Conclusion:This study indicates that interparental conflict have an impact on adolescents’NSSI in Chinese families,and alexithymia and resilience play important roles in the relationship.These findings offer valuable guidance for the prevention and intervention efforts targeting NSSI among adolescents in China and in similar family contexts.

Effect of Dendrobium nobile powder combined with conventional therapy on mild to moderate fatty liver

BACKGROUND Nonalcoholic fatty liver disease(NAFLD)encompasses a variety of liver conditions impacting individuals who consume minimal or no alcohol.Recently,traditional Chinese medicine has been gradually used to treat mild to moderate fatty liver,among which Dendrobium nobile Lindl.powder has been affirmed by many doctors and patients to be effective.However,there is limited research on combining this treatment with standard therapies for mild to moderate NAFLD.AIM To survey the effect of combining Dendrobium nobile Lindl.powder with standard treatment on liver function and lipid metabolism disorder in patients with mild to moderate NAFLD.METHODS Eighty patients with mild to moderate NAFLD participated in this retrospective study,classified into two groups:The observation group(n=40)and the control group(n=40).In November 2020 and November 2022,the study was conducted at People’s Hospital of Chongqing Liang Jiang New Area.The control group received standard treatment,while the observation group received Dendrobium nobile Lindl.powder based on the control group.The study compared differences in traditional Chinese medicine clinical syndrome scores,liver fibrosis treatment,liver function indicators,lipid levels,and serum inflammatory factor levels before and after treatment,and we calculated the incidence of adverse reactions for both groups.RESULTS The total effective rate was 97.50%in the observation group and 72.5%in the control group.After 8 weeks of treatment,the main and secondary symptom scores remarkably decreased,especially in the observation group(P<0.05),and there was a significant reduction in the serum levels of hyaluronic acid(HA),laminin(LN),human rocollagen III(PC III),and collagen type IV(CIV).The levels of HA,LN,PC III,and CIV were significantly lower in the observation group(P<0.05).After 8 weeks,both groups indicated remarkable improvements in liver function and blood lipid levels,with the observation group having even lower levels(P<0.05).Serum levels of interleukin-1β,tumor necrosis factor-α,and interleukin-8 also dropped significantly.The observation group had a lower rate of adverse reactions(5.00%)compared to the control group(22.50%).CONCLUSION Adding Dendrobium nobile Lindl.powder to standard treatment has been found to remarkably improve symptoms and reduce inflammation in patients with mild to moderate fatty liver disease.It also enhances hepatic function and lipid profile,ameliorates liver fibrosis indices,and lowers the risk of side effects.Consequently,this therapeutic protocol shows promise for clinical implementation and dissemination.

Parental Psychological Control and Internet Gaming Disorder Tendency:A Moderated Mediation Model of Core Self-Evaluation and Intentional Self-Regulation

Internet gaming disorder(IGD)among junior high school students is an increasingly prominent mental health concern.It is important to look for influences behind internet gaming disorder tendency(IGDT)in the junior high school student population.The present study aimed to reveal the explanatory mechanisms underlying the association between parental psychological control(PPC)and internet gaming disorder tendency among junior high school students by testing the mediating role of core self-evaluation(CSE)and the moderating role of intentional self-regulation(ISR).Participants in present study were 735 Chinese junior high school students who completed offline self-report questionnaires on parental psychological control,core self-evaluation,intentional self-regulation,and Internet gaming disorder tendency.Analyses were conducted via mediation and moderated mediation.The results showed that:(1)Parental psychological control was positively related to junior high school students’Internet gaming disorder tendency.Core self-evaluation,and intentional self-regulation were negatively related to junior high school students’Internet gaming disorder tendency,respectively.(2)Core self-evaluation partially mediated the relationship between parental psychological control and junior high school students’Internet gaming disorder tendency.(3)Intentional self-regulation moderated the association between parental psychological control and Internet gaming disorder tendency,as well as the relationships between parental psychological control and core self-evaluation and core self-evaluation and Internet gaming disorder tendency in the mediated model.Based on these findings,we believe that there is a need to weaken parental psychological control,strengthen junior high school students’core self-evaluation and intentional self-regulation,and to recognize the important role of parents as well as their children’s personal positive traits in the healthy development of junior high school students.

The Moderating Effect of Organizational Identification on Occupational Stress and Insomnia Among Nurses

Objective:To explore the relationship between organizational identification,occupational stress,and insomnia among nurses and to analyze the moderating role of organizational identification between occupational stress and insomnia.Methods:Through stratified sampling,720 nurses working in a tertiary A-level hospital in Shandong Province from March to May 2021 were surveyed using an effort-reward imbalance questionnaire,an organizational identification questionnaire,and the Athens Insomnia scale.Results:Organizational identification was negatively correlated with occupational stress and insomnia(r_(1)=-0.121,P_(1)<0.01;r_(2)=-0.144,P_(2)<0.01).Occupational stress was positively correlated with insomnia(r=0.379,P<0.01).Organizational identity significantly moderated nurses’occupational stress and insomnia(β=-0.192,t=-2.558,P<0.05).Conclusion:Occupational stress and organizational identification can predict insomnia.Organizational identification could negatively mediate the relationship between occupational stress and insomnia.Improving organizational identification may help alleviate insomnia symptoms by relieving occupational stress.

Analysis of Influencing Factors of Moderate to Severe Malnutrition in Elderly Patients with Lung Cancer during Chemotherapy

Objective:This study aims to identify the factors influencing moderate to severe malnutrition in elderly lung cancer patients undergoing chemotherapy and to provide a basis for developing clinical prevention and intervention strategies.Methods:The clinical data of 150 elderly lung cancer patients who received chemotherapy were retrospectively analyzed.Demographic data,clinical characteristics,laboratory indicators,treatment plans,and other relevant information were collected.Independent risk factors for moderate to severe malnutrition during chemotherapy were identified.Results:During chemotherapy,50 patients(33.33%)developed moderate to severe malnutrition.The BMI of patients with moderate to severe malnutrition was significantly lower than that of patients with no or mild malnutrition(21.20±1.60 vs.26.14±2.31,P<0.001),and the proportion of patients with stage IV tumors was significantly higher(60.00%vs.27.00%,P<0.001).Serum pre-albumin(pre-ALB)and hemoglobin(Hb)levels in patients with moderate to severe malnutrition were significantly lower than those in patients with no or mild malnutrition(152.67±30.41 g/L vs.252.47±51.24 g/L and 102.44±10.09 g/L vs.154.21±15.18 g/L,respectively,P<0.001 for all).Conclusion:Low BMI,decreased serum pre-ALB levels,and decreased serum Hb levels before chemotherapy are independent risk factors for moderate to severe malnutrition in elderly lung cancer patients during chemotherapy.Close clinical attention should be given to these patients,with early intervention measures such as nutritional support to reduce the incidence of malnutrition and improve patients’quality of life and prognosis.

不同强度运动抑制糖尿病大鼠肾脏PI3K/AKT/mTOR信号通路改善自噬的比较

背景:2型糖尿病损害肾功能。研究表明运动干预可以保护肾脏;鸢尾素可以通过抑制磷脂酰肌醇3-激酶/蛋白激酶B/雷帕霉素靶蛋白信号通路恢复自噬,保护糖尿病肾病患者的肾功能。目的:探讨运动能否通过抑制肾脏磷脂酰肌醇3-激酶/蛋白激酶B/雷帕霉素靶蛋白信号通路过度激活来恢复自噬,改善肾损伤,以及分析不同方式运动产生影响的差异。方法:将6周龄的SD大鼠随机分为空白对照组(正常大鼠)和糖尿病组,其中糖尿病组大鼠经过高脂高糖喂养加腹腔注射低剂量1%链脲佐菌素(30 mg/kg)建立2型糖尿病模型。造模成功后再将糖尿病组大鼠随机分成糖尿病模型组、中强度持续运动组和高强度间歇运动组。两个运动组大鼠分别进行8周不同强度运动干预。取材后采用葡萄糖氧化酶法检测大鼠空腹血糖,使用试剂盒检测糖化血红蛋白水平,Elisa法检测血清胰岛素浓度,计算胰岛素抵抗指数,RT-PCR检测肾组织磷脂酰肌醇3-激酶、蛋白激酶B、雷帕霉素靶蛋白、Beclin-1、podocin、nephrin的基因表达量,Western Blot检测肾组织雷帕霉素靶蛋白及自噬标记蛋白LC3-1、LC3-2、Beclin-1的蛋白表达量。结果与结论:①2型糖尿病大鼠空腹血糖和糖化血红蛋白水平极显著性升高,胰岛素抵抗水平显著上升,胰岛素水平显著下降;两种运动均能使2型糖尿病大鼠空腹血糖和糖化血红蛋白水平极显著下降,胰岛素抵抗水平显著下降,胰岛素水平显著上升;与中强度持续运动组相比,高强度间歇运动组胰岛素水平显著上升。②2型糖尿病大鼠podocin、nephrin基因表达量显著降低;两种不同形式运动均能显著提高其表达;与高强度间歇运动组相比,中等强度持续性运动组足细胞相关蛋白基因表达有进一步上升趋势,但无显著性差异。③2型糖尿病大鼠肾组织磷脂酰肌醇3-激酶、蛋白激酶B、mTORC1的mRNA及蛋白的表达量显著增加,自噬标志蛋白Beclin-1、LC3-2表达量以及LC3-2/LC3-1显著降低;两种不同形式运动均能使肾组织磷脂酰肌醇3-激酶、蛋白激酶B、mTORC1的mRNA及雷帕霉素靶蛋白蛋白的表达量显著降低,自噬标志蛋白Beclin-1、LC3-2以及LC3-2/LC3-1显著升高;与中等强度持续性运动组相比,高强度间歇运动的磷脂酰肌醇3-激酶、蛋白激酶B、mTORC1的mRNA及雷帕霉素靶蛋白的蛋白表达量有进一步下降的趋势,Beclin-1、LC3-2以及LC3-2/LC3-1有进一步升高的趋势,但仅Beclin-1有显著性差异。④结果说明2型糖尿病肾脏足细胞损伤,自噬受到抑制,与磷脂酰肌醇3-激酶/蛋白激酶B/mTORC1信号通路被异常激活密切相关。高强度间歇运动和中等强度持续性运动可以保护糖尿病肾脏,减少足细胞损伤,促进自噬恢复,这可能与运动抑制磷脂酰肌醇3-激酶/蛋白激酶B/雷帕霉素靶蛋白信号通路过度激活有关。与中等强度持续性运动相比,高强度间歇运动恢复自噬的效果呈更优趋势,但足细胞蛋白表达稍有下降。

Optimization of copper extraction for bioleaching of complex Cu-polymetallic concentrate by moderate thermophiles

Effects of initial pH, temperature, liquid volume, rotation speed, galvanic interaction （pyrite ratio） and pulp density on bioleaching of complex Cu-polymetallic concentrate were investigated. The results indicated that the copper extraction at pH 1.5 was 1.5 and 1.4 times that at pH 1.0 and pH 2.0 respectively. The copper extraction obtained at 45 ℃ was 1236.8%higher than that at 50 ℃. With the increase of rotation speed or the decrease of liquid volume, copper extraction was improved obviously. Copper extraction was improved gradually with the increase of pyrite ratio. However, when the ratio was higher than 20.0%, no further increase in copper extraction was observed. And the statistically significant interactive effects on copper extraction were found between temperature and pH, and temperature and pyrite ratio.

Surface species of chalcopyrite during bioleaching by moderately thermophilic bacteria

X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of moderately thermophilic bacteria （45 °C）. Results show that monosulfide （CuS）, disulfide （S22？）, polysulfide （Sn2？）, elemental sulfur （S0） and sulfate （SO42？） are the main intermediate species on the surface of chalcopyrite during bioleaching byA. caldus,S. thermosulfidooxidans andL. ferriphilum. The low kinetics of dissolution of chalcopyrite inA. caldus can be mainly attributed to the incomplete dissolution of chalcopyrite and the passivation layer of polysulfide. Polysulfide and jarosite should be mainly responsible for the passivation of chalcopyrite in bioleaching byL. ferriphilumorS. thermosulfidooxidans. However, elemental sulfur should not be the main composition of passivation layer of chalcopyrite during bioleaching.

FINITE ELEMENT MODELING OF MODERATELY THICK COMPOSITE PLATE WITH PIEZOELECTRIC SENSORS AND ACTUATORS

A rectangular finite element for laminated plate with bonded and/or embedded piezoelectric sensors and actuators is developed based on the variational principle and the first order shear deformation theory. The element has four-node, 20-degrees-of-freedom with one potential degree of freedom for each piezoelectric layer to represent the piezoelectric behavior. The higher order derivation of deflection is obtained by using the normal rotation expressions to take the effects of transverse shear deformation into considerations. The finite element can accurately simulate the deformation of both thin and moderately thick plates. A Fortran program is written and a number of benchmark tests are exercised to verify its effectiveness. Results are compared well with the existing data. The unbalanced composite with piezoelectric layers is then analyzed by using the model. Results show that the changes of the ratio between the thickness of positive angle layers and the negative angle layers have an effect on the deformation of the structure under the same electric loading.

调节变量(moderator)辨析：类型、表述和识别

本文扼要阐述了调节变量在社会科学研究中的重要意义,对调节变量的分类、表述、识别检验方法进行了归纳和讨论,并就研究中应注意的有关问题进行了总结.

Source mechanism of small-moderate earth- quakes and tectonic stress field in Yunnan Province

In the paper, source mechanisms of 33 small-moderate earthquakes occurred in Yunnan are determined by modeling of regional waveforms from Yunnan digital seismic network. The result shows that most earthquakes occurred within or near the Chuandian rhombic block have strike-slip mechanism. The orientations of maximum compressive stresses obtained from source mechanism are changed from NNW-SSN to NS in the areas from north to south of the block, and tensile stresses are mainly in ENE-WSW or NE-SE. In the eastern Tibetan Plateau, the orientations of maximum compressive stress radiate toward outside from the plateau, and the tensile stress orientations mostly parallel to arc structures. Near 28N the orientations of both maximum compressive stress and tensile stress changed greatly, and the boundary seems to correspond to the southwestern extended line of Longmenshan fault. Outside of the Chuandian rhombic block, the orientations of P and T axes are some different from those within the block. The comparison shows that the source mechanism of small-moderate events presented in the paper is consistence with that of moderate-strong earthquakes determined by Harvard University, which means the source mechanism of small-moderate events can be used to study the tectonic stress field in this region.

久坐与社区老年人下肢肌力:跌倒恐惧与年龄的中介和调节作用

背景:人体老龄化进程中,下肢肌肉力量会随着年龄的增长呈现显著的生理性下降,久坐、跌倒恐惧、年龄与下肢肌力之间可能存在一定关联,但它们之间的影响路径与效应关系尚不明确。目的:探究社区老年人久坐和下肢肌肉力量之间的关系,并探讨跌倒恐惧和年龄在上述两者关系中的作用。方法:共招募331名60岁及以上的上海市社区老年人。采用问卷调查法收集基本信息、人口学资料等;采用国际身体活动问卷-短卷评估久坐时间,采用30 s坐站测试测量下肢肌力,采用中文版国际跌倒效能量表测评跌倒恐惧。对数据进行描述统计、相关分析、基于回归的路径分析和中介效应检验。结果与结论:最终以318名老年人[78.9%为女性,平均年龄(67.8±5.5)岁]的有效数据纳入分析,其中久坐时间≥3 h的185名,<3 h的133名。①久坐和跌倒恐惧呈正相关关系(P<0.01),下肢肌力和久坐(P<0.01)、跌倒恐惧(P<0.001)均呈负相关关系。②久坐显著负向预测下肢肌力(β=-0.125,P<0.05),久坐显著正向预测跌倒恐惧(β=0.182,P<0.01);跌倒恐惧显著负向预测下肢肌力(β=-0.293,P<0.001)。③跌倒恐惧在久坐和下肢肌力之间起中介作用(β=-0.053,95%CI:-0.100至-0.018)。④久坐对跌倒恐惧的预测效应具有统计学意义(β=0.164,P<0.01),这说明年龄调节了久坐对跌倒恐惧的影响。