The Risk Role of Defeat on the Mental Health of College Students:A Moderated Mediation Effect of Academic Stress and Interpersonal Relationships

Background:College students face significant academic and physiological changes,making them more susceptible to psychological issues such as depression,self-injury,and suicidal ideation.Feelings of defeat can exacerbate these risks by increasing academic stress.However,interpersonal relationships can moderate the impact of academic stress on students’mental health.Utilizing the presage–process–product model,this study aims to empirically investigate how feelings of defeat influence depression,self-injury,and suicidal ideation among college students.Additionally,it explores the mediating role of academic stress and the moderating role of various types of interpersonal relationships.Methods:A total of 1612 college students(750 females,862 males,mean age=19.64±0.62 years)were recruited through cluster sampling.Data were collected via offline questionnaires administered by a trained psychology teacher and a postgraduate student,ensuring high reliability with two examiners per class.Latent profile analysis(LPA)was used to examine the impact of defeat on mental health outcomes,while mediation analysis was conducted to assess the roles of academic stress and interpersonal relationships.Results:1.Defeat is identified as a significant risk factor for mental health issues among college students;2.Four distinct patterns of interpersonal relationships were identified:the interpersonal-relationship risk group,the father–child-relationship high-risk group,the general interpersonal-relationship group,and the superior interpersonal-relationship group;3.Academic stress partially mediates the relationship between defeat and mental health issues such as depression,self-injury,and suicidal ideation;4.Different interpersonal relationship models moderate the impact of academic stress on depression and suicidal ideation.Conclusion:Defeat is a significant risk factor for mental health problems in college students.Academic stress partially mediates the negative impact of defeat on mental health,while patterns of interpersonal relationships moderate this impact.Effective early prevention and intervention should focus on monitoring students’stress levels and fostering warm,positive parent–child relationships.

Tree shrew models:A chronic social defeat model of depression and a one-trial captive conditioning model of learning and memory

Recent genome studies indicate that tree shrew is in the order or a closest sister of primates,and thus may be one of the best animals to model human diseases.In this paper,we report on a social defeat model of depression in tree shrew（Tupaia belangeri chinensis）.Two male tree shrews were housed in a pair-cage consisting of two independent cages separated by a wire mesh partition with a door connecting the two cages.After one week adaptation,the connecting door was opened and a brief fighting occurs between the two male tree shrews and this social conflict session consisted of 1 h direct conflict（fighting） and 23 h indirect influence（e.g.smell,visual cues） per day for 21 days.The defeated tree shrew was considered the subordinate.Compared with na？ve animals,subordinate tree shrews at the final week of social conflict session showed alterations in body weight,locomotion,avoidance behavior and urinary cortisol levels.Remarkably,these alterations persisted for over two weeks.We also report on a novel captive conditioning model of learning and memory in tree shrew.An automatic trapping cage was placed in a small closed room with a freely-moving tree shrew.For the first four trials,the tree shrew was not trapped when it entered the cage and ate the bait apple,but it was trapped and kept in the cage for 1 h on the fifth trial.Latency was defined as the time between release of the tree shrew and when it entered the captive cage.Latencies during the five trials indicated adaptation.A test trial 24 h later was used to measure whether the one-trial trapping during the fifth trial could form captive memory.Tree shrews showed much longer trapping latencies in the test trial than the adaptation trials.The N-methyl-d-aspartate（NMDA） receptor antagonist MK-801（0.2 mg/kg,i.p.）,known to prevent the formation of memory,did not affect latencies in the adaptation trails,but did block captive memory as it led to much shorter trapping latencies compared to saline treatment in the test trial.These results demonstrate a chronic social defeat model of depression and a novel one-trial captive conditioning model for learning and memory in tree shrews,which are important for mechanism studies of depression,learning,memory,and preclinical evaluation for new antidepressants.

Influence of confining prestress on the transition from interface defeat topenetration in ceramic targets

Replica scaled impact experiments with unconfined ceramic targets have shown that the transition velocity,i.e.,the impact velocity at which interface defeat ceases and ceramic penetration occurs,decreased as the length scale increased.A possible explanation of how this scale effect is related to the formation of a cone crack in the ceramic has been presented by the authors in an earlier paper.Here,the influence of confinement and prestress on cone cracking and transition velocity is investigated.The hypothesis is that prestress will suppress the formation and growth of the cone crack by lowering the driving stress.A set of impact experiments has been performed in which the transition velocity for four different levels of prestress has been determined.The transition velocities as a function of the level of confining prestress is compared to an analytical model for the influence of prestress on the formation and extension of the cone crack in the ceramic material.Both experiments and model indicate that prestress has a strong influence on the transition from interface defeat to penetration,although the model underestimates the influence of prestress.

Interface defeat studies of long-rod projectile impacting on ceramic targets

The interface defeat phenomenon always occurs when a long-rod projectile impacting on the ceramic target with certain velocity,i.e.,the projectile is forced to flow radially on the surface of ceramic plates for a period of time without significant penetration.Interface defeat has a direct effect upon the ballistic performance of the armor piercing projectile,which is studied numerically and theoretically at present.Firstly,by modeling the projectiles and ceramic targets with the SPH(Smoothed Particle Hydrodynamics)particles and Lagrange finite elements,the systematic numerical simulations on interface defeat are performed with the commercial finite element program AUTODYN.Three different responses,i.e.,complete interface defeat,dwell and direct penetration,are reproduced in different types of ceramic targets(bare,buffered,radially confined and oblique).Furthermore,by adopting the validated numerical algorithms,constitutive models and the corresponding material parameters,the influences of projectile(material,diameter,nose shape),constitutive models of ceramic(JH-1 and JH-2 models),buffer and cover plate(thickness,constraints,material),as well as the prestress acted on the target(radial and hydrostatic) on the interface defeat(transition velocity and dwell time) are syste matically investigated.Finally,based on the energy conservation approach and taking the strain rate effect of ceramic material into account,a modified model for predicting the upper limit of transition velocity is proposed and validated.The present work and derived conclusions can provide helpful reference for the design and optimization of both the long-rod projectile and ceramic armor.

Ginsenoside Rb1 produces antidepressant-like effects in chronic social defeat stress model of depression through BDNF-TrkB sig⁃naling pathway

OBJECTIVE Ginsenoside Rb1(Rb1),an important bioactive ingredient of Panax ginseng,has potent neuroprotective effects.The objective of the study is to elucidate the impact of Rb1 treatment on chronic social defeat stress(CSDS)-induced depressive-like behaviors and its related mechanism.METHODS AND RE⁃SULTS The daily oral administration of Rb1(35 and 70 mg·kg-1)and imipramine(15 mg·kg-1)for 28 d significantly reversed the social avoidance behavior,anhedonia,and behavioral despair via CSDS exposure,as demonstrated by the consid⁃erable elevation in the time in the zone in social interaction test and consumption of sucrose solu⁃tion in sucrose preference test and decrease of immobility time in forced swim test.Moreover,Rb1 obviously restored the CSDS-induced decrease of BDNF-signaling pathway and hippo⁃campal neurogenesis.Rb1 significantly increased the hippocampal levels of ERK,AKT,and CREB phosphorylation and increased the number of DCX+cells in DG.Importantly,the antidepres⁃sant effects of Rb1 were completely blocked in mice by using K252a(the nonselective tyrosine kinase B inhibitor).CONCLUSION Rb1 exerts promising antidepressant-like effects in mice with CSDS-induced depression,and its effects was facilitated by enhancing the BDNF signaling cas⁃cade and up-regulation of hippocampal neuro⁃genesis.

Defeating cancer:the 150 most important questions in cancer research and clinical oncology

Despite all the human efforts and monetary investment over the last few decades,cancer is still a devastating threat to our life expectancy and quality of life in many parts of the world.The etiology of cancer varies.The genetic and epigenetic causes of cancer are heterogeneous and multifaceted.Early detection is still a

浅析fault, defeat, falling, flaw, shortcoming

Fault, defeat, falling, flaw, shortcoming,这组词(n．)都指人或物在某方面有缺陷，不够完善，以faulI和defeat为常用。

Hyperactivity and Abnormal Exploratory Activity Developing in CD-1 Male Mice under Chronic Experience of Aggression and Social Defeats

Chronic social defeat stress induces diverse effects in mice of different strains and even in animals of the same strain. This paper aims to study the effect of repeated social defeats and, for contrast, repeated aggression in daily agonistic interactions on the behaviors of CD-1 male mice. The behavior of animals that have the same winning and losing track record during 3, 10, 21 days is studied in different tests. The level of aggressiveness, as estimated by the number and total time of attacks, decreases;nevertheless, direct and indirect forms of aggression demonstrated by the aggressive mice (winners) remain significantly high. The number of stereotypic behaviors (rotations and jumps) and total time of digging behaviors are significantly increased in the winners after 21 days compared to 3 and 10 days of intermale confrontations. Among the losers, chronic experience of social defeats is accompanied by the development of pronounced anxiety and a depression-like state estimated by the elevated plus-maze and the Porsolt test scores, respectively. Both groups of male mice with alternative social behaviors demonstrate abnormal locomotor and exploratory behaviors in the open-field test. This phenomenon may be viewed as hyperactivity developed under chronic agonistic interactions and specific for the outbred CD-1 mice. We believe that these animals may be potentially used for modeling the key symptoms of bipolar disorder.

Pathogenesis of chronic social defeat stress model induced depressive-like mouse model according to LC-MS/MS-based metabolomics

OBJECTIVE To explore the pathogenesis of depression according to the LC-MS/MS-based metabolomics in the mouse model which exhibits social avoidance state induced by the chronic social defeat stress model(CSDS).METHODS Twenty male C57BL/6N mice were randomly divided into control group and model group suffering CSDS,and the ICR retired breeder mice were used to attack the model group for 14 d of chronic social defeated stress.The open field test and source preference test were both used to observe depression-like behavior.Besides,the social interaction test is used to observe the social interaction state,especially.After the stress,the serum samples of mice were collected,and the changes of endogenous metabolites were analyzed by LC-MS metabolomics technology,and the pathway analysis of the differential metabolites was performed to explore the pathogenesis of the CSDS induced depressive-like mouse model.RESULTS After the stress of CSDS was completed,the mice in the model group showed a significant slowdown in body weight growth,a reduction in the source preference rate,and a significant reduction in the total distance and the number of rearing in the open field test.Distinctively,the social interaction rate is remarkably decreasing.There are 24 differential metabolites found in the serum of CSDS model mice.CONCLUSION The mouse who suffered CSDS stress would show depressive-like behavior.Based on the LC-MS/MS metabolomics,24 differential metabolites were found in the serum of CSDS model mice.The amino acid metabolism might be significant to the pathogenesis of the CSDS induced depressive-like mouse model.

Effect and regulation ofα-dstroglycan glyco⁃sylation on chronic social defeat induced depressive-like behaviors of mice

OBJECTIVEα-Dstroglycan(α-DG)is a predominant component in the dystrophin-glycoprotein complex(DGC)and a recently char⁃acterized receptor for several extracellular matrix components with high affinity.Recent research⁃es have reported that hypoglycosylation ofα-DG is associated with the pathophysiology of diseas⁃es,especially muscular dystrophy,but little is known about major depressive disorder(MDD).Like-acetylglucosaminyl transferase(Large)is a key enzyme for glycosylation ofα-DG,which mainly modifies two points in the middle domain ofα-DG:Thr-317 and Thr-319.Glycosylatedα-DG(GLY-α-DG)can bind with high affinity to extracellular matrix(ECM)molecules that con⁃tain laminin globular(LG)domains,including per⁃lecan,agrin and neurexin.Agrin is mainly derived from neurons rather than glial cells.In cultured hippocampal neurons,it was found that agrin could regulate the homeostatic plasticity of inhibi⁃tory neurons by acting on GLY-α-DG.Mdx mice are transgenetic models for the investigation of Duchenne muscular dystrophy.Many studies have shown that the expression of GLY-α-DG in the peripheral and brain tissues of Mdx mice is significantly down-regulated.Mdx mice show cognitive impairment and high levels of anxiety.In this study,we employed chronic social defeat stress(CSDS)to establish an animal model of depression and detected the expression of GLY-α-DG among the brain areas associated with the pathophysiology of depression.METHODS So⁃cial interaction test(SIT)and sucrose preference test(SPT)were used to evaluate depressive-like behavior.Open field(OF)and elevated plus maze(EPM)test were used to determine the anxiety-like behavior of Mdx mice.Novelty-sup⁃pressed feeding test(NSFT)forced swim test(FST)and tail suspension test(TST)were used to detect the depressive-like behavior of Mdx mice.Novel object recognition test(NOR)was applied to evaluate the cognition of Mdx mice.Subthreshold social defeat stress was used to explore the susceptibility to stress in Mdx mice.Stereotactic infusion of agrin into the ventral hippocampus(vHip),FST and TST were used to investigate the antidepressant effects of agrin.Adeno-associated virus(AAV)-mediated overex⁃pression techniques,behavior tests and whole-cell path-clamp technique were conducted to determine the impact of Large overexpression on CSDS susceptible mice.RESULTS The expres⁃sion ofα-DG and GLY-α-DG were significantly decreased in the vHip of CSDS susceptible mice.Mdx mice showed decreased expression of GLY-α-DG and increased anxiety-like behav⁃iors.Mdx mice displayed some depressive-like behaviors,and the susceptibility to stress was significantly increased.Downregulation of the expressionα-DG in the vHip by lentivirus increased the susceptibility to stress.Administra⁃tion of agrin to CSDS susceptible mice exerted antidepressant effects,and this effect could par⁃tially sustain for a week.The expression of Large was decreased in vHip.Overexpression of Large through AAV-Large reversed the depressive-like behaviors and restored the decreased frequency and amplitude of mIPSC.CONCLUSION GLY-α-DG and its glycosylase are significantly decreased in CSDS susceptible mice.Adminis⁃tration of agrin and overexpression of Large displays antidepressant effect,which may be related to its promotion of inhibitory synaptic transmission.

Effects of the Novel Anti-Asthenic Drug Ladasten on Behavior and T-Cell Subsets Alterations in a Social Defeat Animal Model of Depression

The aim of the present study was to investigate the effects of the anti-asthenic drug ladasten on behavioral patterns and T-cell subsets in blood, spleen, and thymus in socially stressed male C57Bl/6 mice. Mice subjected to social defeat stress (SDS) for 25 days developed a depressive-like phenotype. The submissive SDS animals were assigned to one of two treatment groups: one group was treated with ladasten (30 mg/kg, i.p.) for up to 5 days, and the other one was administered vehicle as a control. Twenty four hours after the last injection, behavioral parameters were tested, and trunk blood and tissue samples were collected. SDS mice from the vehicle-treated group showed a subordinate and passive avoidance behavior with significantly decreased spontaneous locomotor activity (SLA) and exhibited impaired parameters in the forced swimming test (FST). Changes in behavioral status were correlated with an increase spleen weight, a decrease in thymic index and a shift in the CD4/CD8 balance toward T-cytotoxic cells. The behavior parameters were reversed in the group treated with ladasten compared to the untreated SDS group and were similar to those of unstressed mice. Treatment of socially stressed mice with ladasten normalized the amount of T-lymphocyte cells in the blood, spleen, and thymus. These findings support the notion that depression is accompanied by cell-mediated immune activation and that targeting this pathway may be a new therapeutic approach for treatment. Furthermore, our data support further investigations of ladasten as a potent anti-depressive drug which can be used alone as well as in combination with other anti-depressants.

Santiago the Defeated and the Triumphant

Old fisherman Santiago fight bravely,the battle he loses in the flesh can be one he wins in the spirit.The old man should be regarded as a noble hero,if tragic,a failure for his physical suffers and loses of the big fish,not a failure for his spirit of optimism,confidence,wisdom of spirits,perseverance and bravery.He wins the interior triumph from physical defeat.Whether to be a triumphed hero or a defeated failure is up to a person's efforts.

Victory in Defeat

AFRICAN women have been making headlines this year, with South Africa＇s Home Affairs Minister Nkosazama Dhlamini-Zuma lobbying for the post of African Union chief, Joyce Banda being sworn in as Malawi president and now Nigeria＇s Ngozi Okonjo-Iweala nominated for the top job at the World Bank.

Brain region-specific roles of brain-derived neurotrophic factor in social stress-induced depressive-like behavior

Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response.Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region–specific,particularly involving the corticolimbic system,including the ventral tegmental area,nucleus accumbens,prefrontal cortex,amygdala,and hippocampus.Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology.In this review,we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression.We focused on associated molecular pathways and neural circuits,with special attention to the brain-derived neurotrophic factor–tropomyosin receptor kinase B signaling pathway and the ventral tegmental area–nucleus accumbens dopamine circuit.We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature,severity,and duration of stress,especially in the above-mentioned brain regions of the corticolimbic system.Therefore,BDNF might be a biological indicator regulating stress-related processes in various brain regions.

Sini Powder extract produces antidepressant-like effects in a chronic social defeat stress model of depression in tree shrews

Sini Power（SP） is a famed traditional Chinese formula that has long been used to treat depression. Here, we investigated the effects and possible mechanisms of SP extract on an established model of depression： chronic stressed tree shrew, which mimics the human condition of social stress. The animals were divided into 4 groups. Except for the na？ve group, the other animals were subjected to daily social defeat stress for 5 weeks, and during the last 4 weeks treated with SP extract（3.6 g/kg/d）, fluoxetine（15 mg/kg/d）, and vehicle, respectively. The results showed that SP extract could reverse body weight loss to a certain extent and reduce the levels of urine/serum cortisol that were initially increased by chronic social defeat. In addition, SP extract increased hippocampus norepinephrine concentrations. Our data suggested that SP extract had positive effects on the main depression symptoms in the chronic stressed tree shrew model and that it may be used to help control hypothalamic-pituitary-adrenal axis hyperactivity.

融入美国文化的败北与反思——《鸡尾酒会》中的美日同罪论

《鸡尾酒会》创作于冲绳施政权力复归日本前夜,再现了战后冲绳民众融入美国文化的历程。然而,冲绳民众融入美国文化的过程中伴随着欺骗与挫折,美国人标榜的“国际亲善”被现实戳破,同时宣告了冲绳文化融入美国文化的败北。本文通过分析作品对冲绳民众身份的再定位以及冲绳文化融入美国文化的败北与对美军态度的变迁,结合美国占领冲绳这一时代语境,论证美国的冲绳文化重建政策的败北,从主人公对美日暴行的反思中管窥文本中展现的作者的战争观。

2022年女篮世界杯中国女篮决赛得失分因素分析

2022年女篮世界杯中国女篮取得亚军的优异成绩,但中国女篮与世界强队间仍然存在一定差距。通过文献资料法、录像观察法、数理统计法和比较分析法,对2022年女篮世界杯决赛(中国女篮对阵美国女篮)进行分析,研究中国队的得失分因素,结果显示中国女篮存在进攻效率低、防守能力差、控球能力和组织能力差等问题,同时存在对抗缺乏侵略性、国际大赛经验不足等问题。针对分析结果,提出女篮在今后的训练和比赛中要培养多样性进攻手段、强化自主进攻能力、提高防守的韧性、加强球员国际交流等建议。

谷胱甘肽改善卒中后抑郁和慢性社会挫败应激小鼠行为及其机制研究

目的探究抑郁症的潜在致病机制及谷胱甘肽的改善作用。方法6~8周龄雄性C57BL/6J小鼠分为3组(n=20):无处理对照(SHAM)组、卒中后抑郁(post-stroke depression,PSD)模型组和慢性社会挫败应激(chronic social defeat depression,CSDS)模型组。通过旷场实验、高架十字实验、悬尾实验、糖水偏好实验等验证模型小鼠是否有抑郁样行为表现,取2种模型小鼠以及对照小鼠内侧前额叶皮层(medial prefrontal cortex,mPFC)进行神经递质靶向代谢组学测序。通过主成分分析(principle component analysis,PCA)、相关性分析等方法探索各组小鼠代谢物表达情况、筛选差异代谢物,利用京都基因与基因组百科全书(Kyoto encyclopedia of genes and genomes,KEGG)预测与抑郁模型相关的代谢通路,并对关键差异代谢物谷胱甘肽(glutathione,GSH)的表达以及丙二醛(malondialdehyde,MDA)、谷胱甘肽过氧化物酶4(glutathione peroxidase 4,GPX4)等铁死亡指标进行检测,外源性补充GSH观察模型小鼠抑郁样行为是否改善。结果神经递质靶向代谢组学分析结果显示3组小鼠代谢水平存在明显差异,在mPFC检测到的38种代谢物中,有6种在PSD组中特异性降低,有4种在CSDS组中特异性降低,而GSH、L-天冬酰胺和L-赖氨酸在PSD和CSDS组均表现出明显下降(P<0.05)。KEGG分析结果显示差异代谢物涉及到的主要通路有谷胱甘肽代谢,β-氨基酸代谢,丙氨酸、天冬氨酸和谷氨酸代谢等通路。还原型谷胱甘肽/氧化型谷胱甘肽(glutathione/oxidized glutathione,GSH/GSSG)试剂盒检测发现两种抑郁模型小鼠mPFC还原型GSH明显减少(P<0.05),铁死亡指标检测发现与对照组比较,两种抑郁模型小鼠存在MDA升高并且GPX4阳性细胞比例显著减少的表型(P<0.05),而对抑郁模型小鼠外源补充GSH可增加小鼠高架十字实验开臂时间和旷场实验中央区时间(P<0.05),并且降低悬尾实验静止不动时间(P<0.05),显著改善抑郁样行为表现。结论PSD以及CSDS小鼠脑组织存在13种代谢物失调,其中谷胱甘肽代谢异常引发的铁死亡可能在抑郁症发生中具有重要作用,外源性补充谷胱甘肽可以改善小鼠抑郁样行为。

慢性社交挫败应激模型小鼠纹状体脑区空间转录组的变化

目的通过空间转录组技术探索慢性社交挫败应激(CSDS)模型小鼠纹状体转录组的变化,揭示其在抑郁症发生发展中的作用。方法应用CSDS实验范式建立抑郁样小鼠模型,通过悬尾、强迫游泳、糖水偏爱和社会交互实验分别检测行为绝望、快感缺乏和社交障碍抑郁样指标。选取正常对照小鼠和抑郁样行为明显的CSDS模型小鼠进行纹状体脑区的空间转录组测序,筛选高表达基因,采用DAVID数据库进行KEGG和GO富集分析。结果CSDS模型小鼠行为绝望、快感缺乏和社交回避行为显著增加(P<0.05,P<0.01)。纹状体空间转录组测序结果显示,正常小鼠筛选得到193个纹状体高表达基因;KEGG和GO分析结果显示,高表达基因与纹状体发育、运动行为和药物成瘾行为调节相关,并与环磷酸腺苷信号通路、环磷酸鸟苷/蛋白激酶G信号通路、钙信号、Ras相关蛋白1和丝裂原活化蛋白激酶信号通路高度相关,同时与γ-氨基丁酸能神经元和多巴胺能神经元突触相关。与正常对照小鼠相比,抑郁样行为明显的CSDS模型小鼠纹状体差异基因298个,高度富集于亨廷顿病、阿尔茨海默病和帕金森病等多种神经退行性疾病相关信号通路。结论空间转录组技术能够在空间水平揭示正常小鼠和CSDS模型小鼠纹状体脑区的转录组特征,纹状体可能与抑郁导致神经退行性疾病的病理过程相关。

挫败感对青少年心理健康的影响:压力知觉与人际关系的作用

基于人际关系理论与情绪和应对的认知关系理论,采用追踪数据,以1292名青少年(年龄=14.64±0.63岁)为研究对象,探究挫败感对青少年抑郁、自伤和自杀意念的影响机制。结果显示:(1)挫败感是影响青少年心理健康的风险因素;(2)青少年人际关系有4种模式:人际关系风险组、父子关系高危组、人际关系一般组以及人际关系优势组;(3)压力知觉在挫败感与青少年抑郁、自伤和自杀意念之间起部分中介作用;(4)人际关系模式可以调节该中介模型后半段,即压力知觉对青少年抑郁、自伤和自杀意念的影响,具体表现为随着人际关系得分增加,压力知觉对青少年心理健康影响降低,且在人际关系优势组时压力知觉不可以预测青少年自伤,结果表明人际关系可以缓冲压力的消极影响。研究使用潜剖面分析,揭示了压力知觉和人际关系类型的中介与调节作用,为青少年抑郁、自伤和自杀意念发生发展机制提供更多解释路径。