DNA的振动—内激发—转子模型

本文全面考察了DNA分子链的各种运动自由度,从B型DNA的双螺旋结构出发,建立了DNA的振动动-内激发-转子模型,并由此给出了相应的哈密顿函数、运动方程和孤子解,较为全面地阐明了DNA的动力学特性．     

温针灸联合中药湿热敷治疗脑中风后肢体痉挛的疗效及对患者肢体运动、日常活动能力的影响

目的:研究温针灸联合中药湿热敷治疗脑中风后肢体痉挛的疗效及对患者肢体运动、日常活动功能的影响。方法:选取2017年3月到2018年4月在长春中医药大学附属医院接受脑中风后肢体痉挛治疗患者60例,按照随机数字表法将所有患者分为观察组和对照组各30例,对照组在常规处理的基础上给予温针灸治疗,观察组在对照组的基础上给予中药湿热敷治疗,采用改良Ashworth量表对比患者治疗前后肢体痉挛改善程度,通过Barthel指数评分对比患者治疗前后的日常活动能力,采用Fugl-Meyer评分对两组患者肢体运动能力进行评定。结果:两组治疗15 d和治疗30 d后的上、下肢体痉挛评分与治疗前比较均明显降低,Fugl-Meyer评分与治疗前比较均明显升高(P0.05),且治疗30 d后Fugl-Meyer评分与治疗15 d比较明显升高(P0.05)。治疗15 d、治疗30 d后,观察组上、下肢体痉挛评分均明显低于对照组,Fugl-Meyer评分均高于对照组(P0.05)。两组治疗30 d后Barthel指数评分较治疗前均有上升,且观察组评分显著高于对照组(P0.05)。结论:温针灸联合中药湿热敷治疗对脑中风后肢体痉挛有较好的疗效,能有效恢复患者脑中风后肢体运动功能,改善患者日常活动能力。     

一类具年龄结构和接种的非终生免疫型传染病模型

研究一类具年龄结构和接种的非终生免疫SIRS传染病模型平衡解的稳定性.首先利用特征线法讨论了模型平衡解的存在性,然后利用比较定理和逐次迭代法得到无病平衡解与地方病平衡解全局稳定性的充分条件.     

胶原酶注入小鼠尾状核建立脑出血模型

目的用脑内注射胶原酶方法建立小鼠脑出血模型。方法在动物脑立体定位仪下将肝素化Ⅶ型胶原酶0.15μL(0.5 U/μL)注射到昆明小鼠右侧尾状核内;分别在术后8、12、24、72 h对小鼠运动功能进行检测,通过在各时间点测量血肿直径来观察出血高峰的时间,并对出血部位脑组织进行光镜观察来验证模型制作是否成功。结果术后小鼠即表现左侧肢体偏瘫症状,至12~24 h症状最重。形态学观察证实右侧尾状核区血肿形成,且出血高峰的时间与肢体偏瘫症状发展过程基本一致。不同个体间血肿体积和部位基本一致。结论应用Ⅶ型胶原酶脑内注射的方法建立的小鼠脑出血模型,是一种方法简单,效果可靠,易于大批量制作的动物模型。     

一类S-I传染病模型行波解的存在性

本文研究了一类具有扩散且是非线性传染率的SI传染病模型,分析了模型的行波解的存在性条件,给出了最小波速与产生单调和振荡行波解的条件,并且进行了计算机仿真．     

加压运动对去负荷肌萎缩的影响及机制研究进展

骨骼肌加压运动(KAATSU training)是神经肌肉训练的新方法,通过对肢体近端的适度压迫,可有效闭塞血管、限制血流量,致使肢体远端相对缺血,达到以小强度的骨骼肌加压运动刺激肌肉生长,得到普通大强度抗阻训练的效果。本文主要介绍加压运动的特点、效果和作用,分析加压运动在不同因素下引起的骨骼肌应激性和适应性变化,并对其防治去负荷肌萎缩的前景进行展望。为进一步深入研究提供参考。     

分布时滞竞争模型的周期解

研究了分布时滞竞争模型周期解,利用Gaines与Mawhin的重合度理论,通过构造恰当的Lyapunov函数得到模型正周期解的存在性、唯一性及全局稳定性。     

广义Logistic模型奇摄动问题的渐近分析

本文讨论了一类具有慢变参数的广义Logistic模型的渐近性态.首先,用匹配法构造了其渐近近似解,其次运用上下解法对近似解的一致有效性进行了证明,并给出了近似解与精确解之间的误差估计.最后,通过几个例子将所求近似解与精确解进行了比较,表明了文中方法的有效性.     

脑卒中偏瘫病人肢体运动功能的康复护理训练

目的探讨康复护理训练对脑卒中偏瘫患者肢体功能的影响。方法选取我院于2014年1月至2015年1月收治的脑卒中偏瘫患者86例作为临床研究对象,随机将患者分为观察组和对照组,每组43例。对照组患者采用常规护理,观察组患者在常规护理的基础上加强肢体运动功能的康复护理及训练。比较两组患者的护理效果。结果护理结果表明,观察组患者的Fugl-Meyer运动功能评分明显高于对照组,比较结果具有显著差异性(P0.05)。结论脑卒中偏瘫患者开展康复护理训练有助于肢体运动功能的恢复。     

可兴奋细胞CHAY模型的混沌控制

对可兴奋细胞的Ｃｈａｙ模型的混沌解进行控制。控制的方法为：（１）参数周期扰动;（２）周期激励;（３）周期脉冲（拍）激励。用这三种方法都实现了把混沌转化为周期运动。     

Multijoint Control Strategies Transfer Between Tasks

In this paper, the hypothesis that multijoint control strategies are transferred between similar tasks was tested. To test this hypothesis, we studied the take-off phase of two types of backward somersault dives: one while translating backwards (Back), the other while translating forward (Reverse). An experimentally based dynamic model of the musculoskeletal system was employed to simulate the measured kinematics and reaction force data and to study the sensitivity of take-off performance to initial kinematic conditions. It was found that the horizontal velocity of the total body center of mass (CM) was most sensitive to modifications in the initial shank conditions. Consequently, the initial shank kinematics of the Back dive was modified in the optimization procedure while maintaining the joint coordination of the Back in order to generate the CM trajectory and reaction forces of a Reverse. Similarly, the initial shank kinematics of the Reverse dive was modified to simulate the CM trajectory and reaction force of the Back. It was found that small modifications in the initial shank kinematics led to change in direction of horizontal CM velocity at take-off; resulting in a switch from Back to Reverse and vice versa. In both cases, the simulated momentum conditions at departure and the bimodal shape of the reaction force-time curve were consistent with those experimentally observed. The results of this study support the hypothesis that transfer of control strategies between similar tasks is a viable option in multijoint control. This transfer of control strategy is explained using a hierarchical model of the motion control system.     

The control of twisting somersaults

In the takeoff and early flight phase of a twisting somersault, joint coordination is based on feed-forward control whereas in the late stages of the flight phase configuration adjustments are made using feedback control to ensure accurate completion of the movement and appropriate landing orientation. The aim of this study was to use a computer simulation model of aerial movement to investigate the extent to which arm and hip movements can control twist and somersault rotation in the flight phase of a twisting somersault. Two mechanisms were considered for the control of twist in simulated target trampoline movements with flight times of 1.4 s. In the first case a single symmetrical arm adduction correction was made using delayed feedback control based on the difference between the twist rate in a perturbed simulation and the twist rate in a target movement comprising a forward somersault with 1½ twists. Final corrections were made using symmetrical arm abduction and hip flexion to adjust the twist and somersault angles. In the second case continual asymmetrical arm adduction/abduction adjustments were used to remove the tilt from a perturbed full twisting backward somersault using delayed feedback control based on twist angle and angular velocity. The first method was able to cope with perturbations to a forward somersault with 1½ twists providing the feedback time delay was less than 200 ms. The second method was able to correct a perturbed full twisting backward somersault providing the feedback time delay was less than 125 ms.     

Maximal dismounts from high bar

In men's artistic gymnastics the triple straight somersault dismount from the high bar has yet to be performed in competition. The present study used a simulation model of a gymnast and the high bar apparatus (J. Appl. Biomech. 19(2003a) 119) to determine whether a gymnast could produce the required angular momentum and flight to complete a triple straight somersault dismount. Optimisations were carried out to maximise the margin for error in timing the bar release for a given number of straight somersaults in flight. The amount of rotation potential (number of straight somersaults) the model could produce whilst maintaining a realistic margin for error was determined. A simulation model of aerial movement (J. Biomech.23 (1990) 85) was used to find what would be possible with this amount of rotation potential. The model was able to produce sufficient angular momentum and time in the air to complete a triple straight somersault dismount. The margin for error when releasing the bar using the optimum technique was 28 ms, which is small when compared with the mean margin for error determined for high bar finalists at the 2000 Sydney Olympic Games (55 ms). Although the triple straight somersault dismount is theoretically possible, it would require close to maximum effort and precise timing of the release from the bar. However, when the model was required to have a realistic margin for error, it was able to produce sufficient angular momentum for a double twisting triple somersault dismount.     

Twist limits for late twisting double somersaults on trampoline

An angle-driven computer simulation model of aerial movement was used to determine the maximum amount of twist that could be produced in the second somersault of a double somersault on trampoline using asymmetrical movements of the arms and hips. Lower bounds were placed on the durations of arm and hip angle changes based on performances of a world trampoline champion whose inertia parameters were used in the simulations. The limiting movements were identified as the largest possible odd number of half twists for forward somersaulting takeoffs and even number of half twists for backward takeoffs. Simulations of these two limiting movements were found using simulated annealing optimisation to produce the required amounts of somersault, tilt and twist at landing after a flight time of 2.0 s. Additional optimisations were then run to seek solutions with the arms less adducted during the twisting phase. It was found that 3½ twists could be produced in the second somersault of a forward piked double somersault with arms abducted 8° from full adduction during the twisting phase and that three twists could be produced in the second somersault of a backward straight double somersault with arms fully adducted to the body. These two movements are at the limits of performance for elite trampolinists.     

Maximising somersault rotation in tumbling

Performing complex somersaulting skills during the flight phase of tumbling requires the generation of linear and angular momenta during the approach and takeoff phases. This paper investigates how approach characteristics and takeoff technique affect performance with a view to maximising somersault rotation in tumbling. A five-segment planar simulation model, customised to an elite gymnast, was used to produce a simulation which closely matched a recorded performance of a double layout somersault by the elite gymnast. Three optimisations were carried out to maximise somersault rotation with different sets of initial conditions. Using the same initial linear and angular momentum as the double layout somersault and varying the joint torque activation timings allowed a double straight somersault to be performed with 19% more rotation potential than the actual performance. Increasing the approach velocity to a realistic maximum of 7 ms(-1) resulted in a 42% reduction in rotation potential when the activation timings were unchanged but allowed a triple layout somersault to be performed with an increase of 31% in rotation potential when activation timings were re-optimised. Increasing also the initial angular momentum to a realistic maximum resulted in a 4% reduction in rotation potential when the activation timings were unchanged but allowed a triple straight somersault to be performed with a further increase of 9% in rotation potential when activation timings were re-optimised. It is concluded that the limiting factor to maximising somersault rotation is the ability to generate high linear and angular velocities during the approach phase coupled with the ability to adopt consonant activation timings during the takeoff phase.     

The influence of touchdown conditions and contact phase technique on post-flight height in the straight handspring somersault vault

In vaulting the gymnast must generate sufficient linear and angular momentum during the approach and table contact in order to complete the rotational requirements in the post-flight phase. This study investigated the effects of touchdown conditions and contact technique on peak post-flight height of a straight handspring somersault vault. A planar seven-segment torque-driven computer simulation model of the contact phase in vaulting was evaluated by varying joint torque activation time histories to match three performances of a straight handspring somersault vault by an elite gymnast. The closest matching simulation was used as a starting point to optimise peak post-flight height of the mass centre for a straight handspring somersault. It was found that optimising either the touchdown conditions or the contact technique increased post-flight height by 0.1 m whereas optimising both together increased post-flight height by 0.4 m above that of a simulation matching the recorded performance. Thus touchdown technique and contact technique make similar contributions to post-flight height in the straight handspring somersault vault. Increasing touchdown velocity and angular momentum lead to additional post-flight height although there was a critical value of vertical touchdown velocity beyond which post-flight height decreased.     

Maximising forward somersault rotation in springboard diving

Performance in the flight phase of springboard diving is limited by the amounts of linear and angular momentum generated during the takeoff phase. A planar 8-segment torque-driven simulation model combined with a springboard model was used to investigate optimum takeoff technique for maximising rotation in forward dives from the one metre springboard. Optimisations were run by varying the torque activation parameters to maximise forward rotation potential (angular momentum × flight time) while allowing for movement constraints, anatomical constraints, and execution variability. With a constraint to ensure realistic board clearance and anatomical constraints to prevent joint hyperextension, the optimised simulation produced 24% more rotation potential than a simulation matching a 2½ somersault piked dive. When 2 ms perturbations to the torque onset timings were included for the ankle, knee and hip torques within the optimisation process, the model was only able to produce 87% of the rotation potential achieved in the matching simulation. This implies that a pre-planned technique cannot produce a sufficiently good takeoff and that adjustments must be made during takeoff. When the initial onset timings of the torque generators were unperturbed and 10 ms perturbations were introduced into the torque onset timings in the board recoil phase, the optimisation produced 8% more rotation potential than the matching simulation. The optimised simulation had more hip flexion and less shoulder extension at takeoff than the matching simulation. This study illustrates the difficulty of including movement variability within performance optimisation when the movement duration is sufficiently long to allow feedback corrections.     

The influence of body size on the diving behaviour and physiology of the bimodally respiring turtle, Elseya albagula

In aquatic vertebrates that acquire oxygen aerially dive duration scales positively with body mass, i.e. larger animals can dive for longer periods, however in bimodally respiring animals the relationship between dive duration and body mass is unclear. In this study we investigated the relationships between body size, aquatic respiration, and dive duration in the bimodally respiring turtle, Elseya albagula. Under normoxic conditions, dive duration was found to be independent of body mass. The dive durations of smaller turtles were equivalent to that of larger individuals despite their relatively smaller oxygen stores and higher mass specific metabolic rates. Smaller turtles were able to increase their dive duration through the use of aquatic respiration. Smaller turtles had a relatively higher cloacal bursae surface area than larger turtles, which allowed them to extract a relatively larger amount of oxygen from the water. By removing the ability to respire aquatically (hypoxic conditions), the dive duration of the smaller turtles significantly decreased restoring the normal positive relationship between body size and dive duration that is seen in other air-breathing vertebrates.     

An application of optimal diving models to diving behaviour of Brünnich's guillemots

Although theoretical models predict that the quality of foraging patches has little effect on optimal dive time with increasing depth, many empirical studies show that dive time at a given depth may vary. We developed a model that incorporated patch quality as a parameter of energy intake as a nonlinear function of time, and applied it to the diving behaviour of Brünnich's guillemots, Uria lomvia. The model indicated that optimal dive time can vary widely depending on the parameter. It also explained the convergence of observed dive times with travel time. Assuming the birds dived optimally, this parameter can be estimated from travel time and dive time for each dive. Foraging patches with larger estimated parameter values were favoured by the birds, suggesting that the parameter indicated patch quality. We used this parameter to test an optimal patch use model in divers. The results indicate that Brünnich's guillemots adjust their diving behaviour adaptively depending on patch quality, and that the optimal diving model is valid for prediction of observed dive patterns if patch quality is incorporated appropriately. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

The optimal allocation of time and respiratory metabolism over the dive cycle

Because anaerobic metabolism is much less efficient than aerobicmetabolism in supplying energy, it is widely believed that diversrely predominantly on aerobic metabolism for diving. In thispaper, a time budget model, which assumes that the diver canuse either completely aerobic or partially aerobic metabolismwith additional anaerobic metabolism for diving, is developedand is used to make predictions about patterns in optimal allocationof time and respiratory metabolism during the dive cycle. Theresults derived from the model are (1) a diver that can varythe ratio of energy supplied anaerobically to total energy spentduring dive time is favored by natural selection, but the patternsof time allocation over the dive cycle by the diver do not differ fromthose of a diver that cannot vary the ratio. (2) Even if itis assumed that divers switch their metabolism for diving, anobvious upturn in the surface time with respect to dive timedoes not occur at the aerobic dive limit (ADL) but occurs beyondthe ADL. (3) Use of additional anaerobic metabolism can be favoredfor dives shorter than the ADL. These findings provide a usefulguide to understanding the factors that limit diving behavior.