优秀男子乒乓球运动员躯干旋转力量及其与腰痛的关系探析

目的:探讨乒乓球运动员躯干双侧旋转力量的差异及其与运动员腰痛的关系。方法:通过问卷调查和临床诊断,将16名优秀男子乒乓球运动员分为腰痛组和健康组,通过等速测力系统对两组运动员的躯干旋转力量(PT)、躯干双侧旋转力量比(正手侧/反手侧)进行测试。结果:角速度为60°/s时,健康组和腰痛组的躯干正反手侧最大旋转力量均存在显著性差异(P<0.05);角速度为120°/s时,健康组的躯干正反手侧最大旋转力量存在显著性差异(P<0.05),腰痛组的躯干正反手侧最大旋转力量存在非常显著性差异(P<0.01)。角速度为60°/s和120°/s时,健康组与腰痛组之间躯干正反手侧最大旋转力矩均无显著性差异,但健康组的正手侧旋转/反手侧旋转力量比值大于腰痛组(P<0.05)。结论:优秀男子乒乓球运动员存在躯干双侧旋转力量失衡现象,提示躯干旋转力量失衡过大可能是导致乒乓球运动员腰痛的原因之一。     

膝骨关节炎患者步态动力学相关参数分析

目的:分析膝关节骨性关节炎(KOA)患者下肢关节的动力学变化特点,为进一步研究其发病机制及临床治疗提供依据。方法:选取胫股关节OA患者60名,根据K/L影像分级分为轻型患病组(LKOA)和重型患病组(MKOA);另取年龄、性别、体重、身高与患病组相当的30名正常受试者作为健康对照组(CON)。利用VICON三维动作分析系统测试并比较实验对象下肢各关节动力学相关参数。结果:支撑早期,LKOA组膝关节最大外展力矩大于MKOA组和CON组(P<0.001);MKOA组支撑期中期膝关节内收力矩第1峰值显著大于LKOA组(P<0.05)和CON组(P<0.001);LKOA组支撑末期膝关节内收力矩第2峰值明显低于CON组(P<0.05);MKOA组髋关节内收力矩第1峰值显著低于CON组(P<0.05)。结论:胫股关节KOA病情越重,膝关节内侧面负荷越大;与健康人相比,OA患者髋关节外展力矩较大,重型患者髋关节内收力矩较小。     

藤黄霖对微波诱发大鼠脾脏淋巴细胞损伤的影响

目的观察藤黄霖对微波诱发的大鼠脾脏T、B淋巴细胞亚群损伤的影响,并探讨其对微波辐射致大鼠免疫功能损伤的防护作用及相关机制。方法清洁级雄性SD大鼠80只,随机分为正常对照组(CON组)、辐照组(RAD组)、安多霖组(ADL组)和藤黄霖组(THL组),每组20只。照射前灌胃给药,1次/d,连续给药7d。随后RAD组、ADL组和THL组大鼠经功率密度为30m W/cm2的微波全身辐照15min,CON组行假照射。辐照后7、14d检测大鼠脾脏CD3+、CD4+、CD8+T细胞亚群和CD45RA+B细胞亚群的变化。结果微波辐照后7d,RAD组大鼠脾脏系数明显低于CON组及THL组(P<0.05),脾脏CD4+T细胞比例明显低于CON组(P<0.05),CD8+T细胞比例明显高于CON组(P<0.05),而THL组脾脏CD3+T细胞、CD4+T细胞比例均明显高于RAD组和ADL组(P<0.05)。辐照后14d,RAD组脾脏CD8+T细胞和THL组脾脏CD3+T、CD4+T细胞比例明显高于CON组(P<0.05)。辐照后7d,R AD组脾脏CD4+/CD8+比值低于CON组(P<0.05),辐照后14d恢复到CON组水平;辐照后7d,THL组脾脏CD4+/CD8+比值明显高于RAD组(P<0.05),辐照后14d,THL组脾脏CD4+/CD8+比值明显低于ADL组,而与CON组及RAD组比较未见明显差异。辐照后7d,RAD组脾脏CD45RA+B细胞比例明显低于CON组及ADL组(P<0.05),而辐照后14d各组比较差异无统计学意义(P>0.05)。结论微波辐照早期大鼠脾脏T、B淋巴细胞显著减少,由于CD4+T淋巴细胞比例迅速降低,导致CD4+/CD8+比值下降而引发机体免疫失衡。中药复方藤黄霖能够提高微波辐照大鼠脾脏T、B淋巴细胞比例并改善CD4+/CD8+比值失衡状态。     

Thera-Band训练在肩袖损伤术后康复中的应用效果分析

目的 探讨Thera-Band训练在肩袖损伤术后康复中的应用效果。方法 选取2020年2月至2021年2月信阳一五四医院收治的拟行关节镜下肩袖修补术治疗的62例肩袖损伤患者作为研究对象,按照随机数表法将其随机分为观察组(31例)和对照组(31例),对照组患者术后采用常规康复训练,观察组患者术后在常规康复训练的基础上应用Thera-Band训练,对比观察两组患者肩关节功能、疼痛程度、内外旋峰力矩以及临床疗效。结果 术后16周,观察组患者加利福尼亚大学洛杉矶分校肩关节评分系统(UCLA)评分明显高于对照组(t=8.610,P<0.001),视觉模拟评分法(VAS)评分明显低于对照组(t=6.944,P<0.001),内旋峰力矩及外旋峰力矩均明显大于对照组(t=2.053、2.159,P=0.045、0.035);观察组患者肩关节功能恢复优良率为90.32%,明显优于对照组患者的肩关节功能恢复优良率67.74%(χ²=4.769,P=0.029)。结论 Thera-Band训练可有效减轻肩袖损伤患者术后疼痛程度,改善肩关节功能,疗效显著。     

锁定加压钢板内固定在肱骨骨折患者中应用及安全性研究

目的探讨锁定加压钢板内固定在肱骨骨折患者中的临床治疗效果及安全性。方法选取自2014年8月至2016年11月收治的肱骨骨折患者90例,采用随机数字法分为A组(n=45)与B组(n=45)。A组采用普通钢板内固定治疗,B组采用锁定加压钢板内固定治疗。观察两组患者术后围术期指标(手术时间、住院时间、出血量及骨折愈合时间);治疗前及治疗后6个月分别对两组患者进行肩关节Constant评分及上肢功能手臂与肩关节运动障碍(DASH)评分评价;统计并比较两组患者并发症发生情况。结果两组患者住院时间比较,差异无统计学意义(P>0.05)。B组患者手术时间、出血量及骨折愈合时间均低于A组,差异有统计学意义(P<0.05)。治疗前,两组患者肩关节Constant评分及DASH评分比较,差异无统计学意义(P>0.05);治疗后6个月,肩关节Constant评分及DASH评分均较治疗前改善,且B组肩关节Constant评分高于A组,DASH评分低于A组,差异均有统计学意义(P<0.05)。治疗后,B组并发症发生率为4.4%(2/45),低于A组的17.7%(8/45),差异有统计学意义(P<0.05)。结论肱骨骨折患者采用锁定加压钢板内固定治疗效果理想,安全性较高,能促进手臂功能恢复。     

长期坚持体育锻炼与SOD、LPO的关系

本资料对老年健康组、老年锻炼组和老年疾病组,分别检测了超氧化物歧化酶(SOD)和过氧化脂质(LPO)的水平。发现:(1)锻炼组 SOD 活性高于健康组(P<0.01),明显高于疾病组(P<0.001),健康组 SOD 活性高于疾病组(P<0.01);(2)锻炼组 LPO 含量明显低于健康组和疾病组(P<0.001),健康组 LPO 含量低于疾病组(P<0.05)。上述结果提示:长期坚持体育锻炼有抗病防衰效果;慢性疾病有促进和加速衰老的作用。     

超声引导下可视针刀治疗肩胛上神经卡压综合征效果观察

目的:观察超声引导下可视针刀治疗肩胛上神经卡压综合征的效果。方法:选择肩胛上神经卡压综合征60例,随机分为观察组和对照组各30例。观察组采用超声引导下针刀闭合性松解术治疗,对照组采用常规神经阻滞治疗。两组均每周治疗1次,3次为1个疗程。比较两组总体疗效及治疗前后患者压痛情况(VAS)、Constant-Murley肩关节功能评分改善情况。结果:观察组愈显率90.0%,显著高于对照组的63.3%(P<0.05)。治疗3个月后,两组VAS分值均较治疗前显著下降,但观察组VAS分值显著低于对照组(P<0.05);观察组在治疗2周后开始肩关节功能分值即显著高于治疗前,对照组在治疗3个月后肩关节功能分值显著高于治疗前(P<0.05)。结论:超声引导下可视针刀治疗肩胛上神经卡压综合征疗效优于常规神经阻滞治疗。     

肩胛肌肉强化训练治疗慢性肩袖损伤临床研究

目的:探讨肩胛肌肉强化训练治疗慢性肩袖损伤后功能障碍的临床疗效。方法:选择肩袖损伤肩关节功能障碍患者48例,随机分为对照组(22例)和治疗组(26例)。对照组进行理疗、运动疗法及关节松动术,l次/日,10次为1个疗程,共进行2个疗程,各疗程间无间隔。治疗组增加肩胛肌肉强化训练康复手段,包括对冈上肌、冈下肌、小圆肌、肩胛提肌、菱形肌、上下斜方肌、背阔肌等进行牵伸、松解、稳定性和本体感觉训练等系统康复手段。所有患者于治疗前后行肩关节活动范围(ROM)和UCLA肩关节功能评分系统评定。结果:纳入患者48例全部进入结果分析。两组患者治疗2个疗程后肩关节ROM及UCLA评分变化:1对照组治疗2个疗程后,肩关节ROM及UCLA评分均提高,与本组治疗前比较差异有显著性意义(P<0.05);2治疗组治疗2个疗程后肩关节ROM及UCLA评分均明显改善,与本组治疗前比较差异有显著性意义(P<0.05);与对照组治疗后比较差异有显著性意义(P<0.05)。结论:肩胛肌肉放松及强化训练改善肩袖损伤患者肩关节活动范围,提高肩关节运动功能的临床疗效显著。     

不同恢复方式对去负荷大鼠腓肠肌纤维类型组成的影响

目的:探讨自然恢复和离心运动恢复等再负荷方式对废用性骨骼肌纤维横截面积及类型的影响。方法:采用尾部悬吊模型。24只成年雌性SD大鼠按体重随机分为对照组(CON)、尾部悬吊组(TS),悬吊14天后解悬吊自然恢复组(NR)和悬吊14天后离心运动恢复组(ER),每组6只。离心运动为每天下坡跑1h,坡度-5%,跑速16 m/min,共2周。取大鼠腓肠肌进行异染性染料ATPase染色,计算腓肠肌纤维组成百分比和肌纤维横截面积(CSA)。结果:(1)TS组大鼠腓肠肌I型%和IIa%显著低于CON组(P<0.01),IIb%显著高于CON组(P<0.01);TS组Ⅰ型肌纤维CSA较CON组减少42.2%(P<0.01),Ⅱa型肌纤维CSA减少30.0%,Ⅱb型肌纤维CSA减少了17.9%(P<0.01)。(2)NR组I%与CON组无显著差异,IIa型和IIb型肌纤维CSA与CON组无显著差异。(3)ER组I%、IIa%和IIb%和横截面积均与CON组无显著性差异。(4)ER组与NR组相比,I%无显著性差异,IIa%高12.54%(P<0.01),IIb%低14.63%(P<0.01);ER组Ⅰ型肌纤维CSA为NR组的1.18倍(P<0.01),两组Ⅱa和Ⅱb型肌纤维CSA则没有显著性差异。结论:尾部悬吊造成骨骼肌废用性肌萎缩,与自然恢复相比,离心运动能较好地使废用性萎缩骨骼肌的面积和肌纤维组成百分比得到恢复。     

艾灸治疗优秀乒乓球运动员痛经疗效观察

目的:观察艾灸疗法对优秀乒乓球运动员原发性痛经的疗效及其对激素水平的影响。方法:28名15～24岁、符合原发性痛经诊断标准的优秀乒乓球运动员,随机分为艾灸治疗组(14例)和月月舒治疗组(14例)。艾灸治疗组从月经来潮前3天开始,在患者腹部气海、关元和中极穴区域和背部八髎穴至腰阳关穴区域施灸,至经期第2天结束,每日1次,连续5天。月月舒治疗组从月经来潮前3天开始口服月月舒冲剂,至经期第2天结束,连续5天,每次1包,每日2次。两组均连续治疗3个月经周期。分别于治疗前和3个月经周期后,所有28名痛经运动员经期第2天采集经血,检测经血前列腺素F2α(PGF2α);月经来潮24小时内,晨8～9时抽取静脉血,采用放射免疫分析法检测催产素(Oxytocin,OT)。另选14名年龄相仿且无原发性痛经的优秀乒乓球运动员作为正常对照组,同样方法检测其经血PGF2α和静脉血OT。结果:(1)艾灸治疗组愈显率、有效率分别为85.7%、100%,月月舒治疗组分别为28.5%和85.7%,组间比较差异有统计学意义(P<0.01,P<0.05)。(2)两组治疗前经血PGF2α含量均高于正常对照组,差异有统计学意义(P<0.01);两组治疗后经血PGF2α含量较治疗前均下降,差异有统计学意义(P<0.01);两组间治疗前、后经血PGF2α含量比较差异无统计学意义。(3)治疗前两组运动员经期血浆OT含量均显著高于正常对照组(P<0.01);治疗后两组运动员血浆OT含量较治疗前均显著降低(P<0.01);艾灸治疗组治疗后较月月舒治疗组显著降低(P<0.05),并恢复到正常对照组水平(P>0.05),而月月舒治疗组治疗后未达正常组水平。(4)痛经运动员经期血浆OT含量与痛经程度之间存在正相关。结论:艾灸疗法对优秀乒乓球运动员原发性痛经疗效显著,其原理可能是通过调节患者异常的前列腺素F2α及催产素水平而发挥作用。     

Internal impingement in the tennis player: rehabilitation guidelines

Internal impingement is a commonly described cause of shoulder pain in the overhead athlete, particularly in tennis players. Three shoulder dysfunctions, often correlated with internal impingement symptoms, require attention in the rehabilitation strategy of internal impingement in the tennis player: (1) acquired glenohumeral anterior instability, (2) loss of internal rotation range of motion, and (3) lack of retraction strength. Based on recent literature, the following guidelines are proposed in the rehabilitation of the tennis player with internal impingement symptoms: (1) shoulder rehabilitation should be integrated into kinetic chain training, not only in the advanced phases of the athlete's rehabilitation, but from the initial phases; (2) both angular and translational mobilisations can be used in the treatment of acquired loss of glenohumeral internal rotation range of motion to stretch the posterior structures of the glenohumeral joint; and 3) in the rehabilitation of scapular dyskinesis, the therapist should focus on restoration of intramuscular trapezius muscle balance in the scapular exercises, with special attention to strength training of the retractors.     

Shoulder Instability in Professional Rugby Players-The Significance of Shoulder Laxity

OBJECTIVE:: Shoulder instability is a common cause of morbidity among professional rugby union players. This study explores whether the risk of shoulder dislocation is associated with innate shoulder laxity. DESIGN:: Retrospective cohort study. SETTING:: Clinical sports medicine research at professional rugby clubs. PARTICIPANTS:: One hundred sixty-nine healthy rugby players (mean age 25.1 years) with no history of instability in either shoulder and 46 players (mean age 27.5 years) with shoulder instability in one shoulder (patient group). MAIN OUTCOME MEASURES:: Anterior, inferior, and posterior laxity was measured in both shoulders for healthy players and in the uninjured shoulder only for injured players using dynamic ultrasound. RESULTS:: There was no significant difference between the nondominant (anterior: mean 2.9 ± 1.2 mm; inferior: mean 3.1 ± 1.0 mm; posterior: mean 5.1 ± 1.7 mm) and dominant (anterior: mean 3.1 ± 1.1 mm; inferior: mean 2.9 ± 1.0 mm; posterior: mean 4.9 ± 1.7 mm) shoulders in healthy players (P > 0.05). The comparison between healthy shoulders (anterior: mean 3.0 ± 1.2 mm; inferior: mean 3.0 ± 1.0 mm; posterior: mean 5.0 ± 1.7 mm) and the uninjured shoulder (anterior: mean 4.2 ± 1.7 mm; inferior: mean 3.4 ± 1.2 mm; posterior: mean 6.2 ± 3.0 mm) from injured players identified that players with unstable shoulders have a significantly higher shoulder translation in their uninjured shoulder than healthy players (P < 0.05). CONCLUSIONS:: Formal assessment of shoulder translation using dynamic ultrasound should enable sports medicine practitioners to identify players at greatest risk of subsequent shoulder instability for targeted prehabilitation programs.     

Upper limb joint kinetic analysis during tennis serve: Assessment of competitive level on efficiency and injury risks

The aim of this work was to compare the joint kinetics and stroke production efficiency for the shoulder, elbow, and wrist during the serve between professionals and advanced tennis players and to discuss their potential relationship with given overuse injuries. Eleven professional and seven advanced tennis players were studied with an optoelectronic motion analysis system while performing serves. Normalized peak kinetic values of the shoulder, elbow, and wrist joints were calculated using inverse dynamics. To measure serve efficiency, all normalized peak kinetic values were divided by ball velocity. t‐tests were used to determine significant differences between the resultant joint kinetics and efficiency values in both groups (advanced vs professional). Shoulder inferior force, shoulder anterior force, shoulder horizontal abduction torque, and elbow medial force were significantly higher in advanced players. Professional players were more efficient than advanced players, as they maximize ball velocity with lower joint kinetics. Since advanced players are subjected to higher joint kinetics, the results suggest that they appeared more susceptible to high risk of shoulder and elbow injuries than professionals, especially during the cocking and deceleration phases of the serve.     

Mobility impairment, muscle imbalance, muscle weakness, scapular asymmetry and shoulder injury in elite volleyball athletes

BACKGROUND: The aim of this study was to evaluate the relationship between shoulder mobility, rotator muscles' strength and scapular symmetry, and shoulder injuries and/or pain in elite volleyball athletes. METHODS: An isokinetic shoulder muscle strength test, which was performed at speeds of 60/sec and 180/sec, and shoulder mobility and scapula lateral slide tests were conducted bilaterally on 16 subjects, who represented the England elite volleyball players. The subjects also prospectively completed monthly questionnaires during the competition season to report on their shoulder condition. RESULTS: The results showed that the active range of shoulder internal rotation and concentric external rotators' strength in the dominant arm were significantly less, than in the non-dominant arms, but the internal rotators were significantly stronger in both concentric and eccentric tests at both testing speeds. Seven of 16 subjects indicated overt shoulder injury or pain during their training season, nine subjects had shoulder mobility impairment, seven had muscle imbalance, 13 had relative muscle weakness and five had scapular asymmetry. The association between shoulder muscle strength imbalance (eccentric external < concentric internal) of rotators in the dominant arm and shoulder injuries was statistically significant (Fisher's exact test, p<0.05). CONCLUSIONS: We conclude that rotator muscle strength imbalance may play an important role in shoulder injuries in high-level volleyball players.     

乒乓球运动员发球动作识别时的神经效率——来自EEG的证据

目的:探讨乒乓球运动员识别发球动作时具有大脑皮层活动减少的特征。方法:采用64导脑电测试系统记录18名乒乓球运动员和18名乒乓球初学者观看发球旋转的动作视频时的脑电数据,共有160个发球动作视频,在视频结束时被试进行旋转的判断,基于事件前的脑电基值,计算在动作识别过程中alpha频率的事件相关去同步化(ERD),了解大脑皮层激活状态的变化。结果:与运动新手相比,运动专家在动作识别过程中高频alpha(10.5~12.5 Hz)的ERD幅度更低。与运动新手相比,运动专家在正确识别发球动作时高频alpha频段的ERD在顶叶皮层(P<0.05)和枕叶皮层的幅值更低(P<0.01)。结论:乒乓球运动员专项动作识别存在神经效率,与更低幅度alpha频率的ERD相联系。乒乓球运动员发球动作识别时大脑顶叶和枕叶的能量消耗较小。     

Kinematic and muscle activity characteristics of multidirectional shoulder joint instability during elevation

Alterations of shoulder motion have been suggested to be associated with shoulder disorders. The objective of this study was to perform a 3D motion analysis (kinematic and electromyographical) of skeletal elements and muscles of shoulder joint in patients with multidirectional instability. Fifteen patients with multidirectional instability and 15 normal controls were investigated during continuous elevation in the scapular plane. The spatial coordinates of 16 anatomical points of the shoulder to determine kinematical parameters were quantified by an ultrasound-based motion analyzer. The activities of 12 muscles were measured by surface electromyography. Kinematic characteristics of motion were identified by scapulothoracic, glenohumeral, and humeral elevation angles; range of angles; scapulothoracic and glenohumeral rhythm; scapulothoracis, glenohumeral, and scapuloglenoid ratios; and the relative displacement between the rotation centers of the humerus and the scapula. The electromyographical characteristics of motion were modeled by the on–off pattern of muscle activity. Significant alterations in kinematical parameters were observed between patients and asymptomatic volunteers. The anterior, posterior, and inferior dislocations of shoulders with multidirectional instability could be properly modeled by the relative displacement between the rotation centers of the scapula and humerus. The shorter activity by m. pectoralis maior and all three parts of m. deltoideus and longer activity by m. supraspinatus, m. biceps brachii, and m. infraspinatus assure the centralization of the glenuhumeral head of a shoulder with multidirectional instability.     

Effect of ballistic and power training on performance adaptations of élite table tennis players

The purpose of this study was to examine the effects of ballistic and power training on the skills, physical fitness and body composition adaptations of élite table tennis players. Thirty male table tennis players (age: 24?±?7 years, stature: 175?±?6 cm, body mass 74?±?16 kg, percentage of fat mass (%FM) 12?±?7%, mean?±?SD), who were able to perform top spin strike properly, were randomly assigned to three groups: power training (PT), ballistic training (BT) and no training (Control, CON). PT and BT trained 3 times per week for 8 weeks. PT consisted of three sets for six different stations, 60–80% of one repetition maximum (1RM). BT consisted of three sets for five different throwing exercises. Pre- and post-intervention group comparisons were analyzed using a two-way ANOVA with repeated measurements of two factors (group?×?time). After training, significant interactions were observed in increasing muscle strength, muscle endurance, explosive power, anaerobic power, agility and grip strength regardless of the exercise methods (p?<?0.05). Moreover, both training regimens were not effective in changing body composition, reaction time and skills (p?>?0.05). In conclusion, the results of the present study suggest that physical fitness adaptations can be increased similarly after 8 weeks of power and ballistic training, in table tennis players. So coaches and elite table tennis players can use ballistic and power training to improve their performance without having to worry about the negative impact of their training on their skill and explosive power performance.

     

Technique effects on upper limb loading in the tennis serve

The purpose of this study was to compare the shoulder and elbow joint loads during the tennis serve. Two synchronised 200 Hz video cameras were used to record the service action of 20 male and female players at the Sydney 2000 Olympics. The displacement histories of 20 selected landmarks, were calculated using the direct linear transformation approach. Ball speed was recorded from the stadium radar gun. The Peak Motus system was used to smooth displacements, while a customised inverse-dynamics program was used to calculate 3D shoulder and elbow joint kinematics and kinetics. Male players, who recorded significantly higher service speeds (male = 183 km hr(-1): female = 149 km hr(-1)) recorded significantly higher normalised and absolute internal rotation shoulder torque at the position when the arm was maximally externally rotated (MER) (male = 4.6% and 64.9 Nm: female = 3.5% and 37.5 Nm). A higher absolute elbow varus torque (67.6 Nm) was also recorded at MER, when compared with the female players (41.3 Nm). Peak normalised horizontal adduction torque (male = 7.6%: female = 6.5%), normalised shoulder compressive force (male = 79.6%: female = 59.1%) and absolute compressive force (male = 608.3 N: female = 363.7 N), were higher for the male players. Players who flexed at the front knee by 7.6 degrees, in the backswing phase of the serve, recorded a similar speed (162 km hr(-1)), and an increased normalised internal rotation torque at MER (5.0%), when compared with those who flexed by 14.7 degrees. They also recorded a larger normalised varus torque at MER (5.3% v 3.9%) and peak value (6.3% v 5.2%). Players who recorded a larger knee flexion also recorded less normalised and absolute (4.3%, 55.6 Nm) peak internal rotation torque compared with those with less flexion (5.6%, 63.9 Nm). Those players who used an abbreviated backswing were able to serve with a similar speed and recorded similar kinetic values. Loading on the shoulder and elbow joints is higher for the male than female players, which is a reason for the significantly higher service speed by the males. The higher kinetic measures for the group with the lower knee flexion means that all players should be encouraged to flex their knees during the backswing phase of the service action. The type of backswing was shown to have minimal influence on service velocity or loading of the shoulder and elbow joints.