Human-like reflex control for an artificial hand

In this paper, we illustrate the low level reflex control used to govern an anthropomorphic artificial hand. The paper develops the position and stiffness control strategy based on dynamic artificial neurons able to simulate the neurons acting in the human reflex control. The controller has a hierarchical structure. At the lowest level there are the receptors able to convert the analogical signal into a neural impulsive signal appropriate to govern the reflex control neurons. Immediately upon it, the artificial motoneurons set the actuators inner pressure to control the finger joint position and moment. Other auxiliary neurons in combination with the motoneurons are able to set the finger stiffness and emulate the inverse myotatic reflex control. Stiffness modulation is important both to save energy during task execution, and to manage objects made of different materials. The inverse myotatic reflex is able to protect the hand from possible harmful external actions. The paper also presents the dynamic model of the joints and of the artificial muscles actuating Blackfingers, our artificial hand. This new type of neural control has been simulated on the Blackfingers model; the results indicate that the developed control is very flexible and efficient for all kind of joints present in the humanoid hand.     

Nonlinear viscoelastic behaviour of the flexor tendon of the human hand

The mechanical behaviour of the flexor tendon of the human hand is here investigated from the point of view of its nonlinear viscoelasticity. The samples are subjected to several single and multiple step loading histories. A quasilinear viscoelastic constitutive relationship between strain and stress history is assumed. Its characteristic material functions are determined with the aid of simple creep results, and model predictions are compared with the experimental results of complex loading histories. The validity of the quasilinear approach to tendon behaviour is discussed in connection with the deformation mechanism suggested by it.     

Early joint and tendon reconstruction for a degloving injury to the dorsum of the hand

Primary insertion of inert material into an open wound to expedite joint and tendon reconstruction can be safely accomplished if the wound is thoroughly debrided and the material is covered with a well-vascularized flap. In this case, metacarpophalangeal mobility and extensor tendon function were largely preserved by early insertion of silicone spacers and rods in the reconstruction of a severe degloving injury to the dorsum of the hand.     

Connective tissue reinforcing structures of the digital tendon sheaths of the human hand

At a greater number of humid preparated human hands, all the ligamentous supports of the digital tendon sheath were exposed and their dimensions were determined. The osteofibrous channels, which contain the long flexor tendons of the digits, were bounded on the one hand by transversely concave shaft areas of the phalanges and the palmar ligaments and on the other side by the fibrous parts of the tendon sheath. From the second to the 5th finger, it has a regular extension of length, which begins proximal at the heads of the metacarpal bones and runs distal to the base of the nail phalanx. In some cases, there is a continuous communication between the digital tendon sheath of the little finger and the carpal synovial sheath. The tendon sheath of the flexor pollicis longus muscle in comparison with it is always in an open communication with the radial synovial sac of the wrist. At the fibrous supports of the digital tendon sheath, one can find constant and inconstant ligamentous structures. Regular shaped ligaments consist of annular fibers (A1 to A5). The proximal complex of fiber supports is a formation of the A1 and A2 ligaments. The band A1 can be divided into 2 ligaments both of roughly equal length, which lay between the head of the metacarpal bone and the base of the proximal phalanx. The strongest fibrous support of the whole digital tendon sheath represents the band A2. It is attached to the midth of the proximal phalanx and increases in strength from proximal to distal. The middle length varies between 6.7 mm at the thumb and 18.7 mm at the middle finger. The distal margin is strengthened by fibrocartilage tissue to be in accordance with the important function as a pulley. The annular band A4 forms the distal supporting complex height above the shaft of the middle phalanx. At the 2nd to the 5th finger it is, with a middle length of 6 to 7 mm, very much shorter than A2 and restrains first of all the tendon of the flexor digitorum profundus muscle. In the area of the interphalangeal joints, we can find the annular bands A3 and A5, which fiber texture is formed variable. Both ligaments are attached on either both sides with the joint capsule and the palmar plate. The other inconstant supports of the digital sheaths are systematically recorded indeed (C1 to C3), but only in exceptional cases they exist of cruciform fibers (Lig. cruciatum).(ABSTRACT TRUNCATED AT 400 WORDS)     

Re-occurrence of filamentous planktonic cyanobacteria during permanent artificial destratification

In a whole-lake long-term experiment of permanent artificialdestratification, the filamentous planktonic cyanobacterium,Limnothrix (Oscillatoria) redekei (Van Goor) Meffert (1988),re-occurred at the end of the third year, after complete absencefor 2 years. The cyanobacteria peaked at the end of the fourthyear of permanent destratification, the biomass being much higherthan during the pre-destratification period. Limnothrix (Oscillatoria)redekei is obviously a turbulence-tolerant cyanobacterial species.     

Control of a single degree of freedom artificial hand

A commerical single degree of freedom artificial hand has been fitted with touch, slip and position sensors, which permit low-level control tasks to be performed by a microprocessor; little conscious effort is required by the wearer. Hardware and software for the microprocessor system are described.     

基于思维脑电信号的假手的研究

本文主要研究利用思维脑电信号来控制假手动作。采用小波变换对思维脑电信号进行分解,选取合适的子带信号并提取相应能量特征,组成特征向量输入BP神经网络进行分类识别。整个信号处理过程在LabVIEW软件平台上实现,并利用其串口通信模块输出控制指令来控制假手的张开和闭合。     

Withdrawal of artificial nutrition and hydration for patients in a permanent vegetative state: changing tack

In the United States, the decision of whether to withdraw or continue to provide artificial nutrition and hydration (ANH) for patients in a permanent vegetative state (PVS) is placed largely in the hands of surrogate decision-makers, such as spouses and immediate family members. This practice would seem to be consistent with a strong national emphasis on autonomy and patient-centered healthcare. When there is ambiguity as to the patient's advanced wishes, the presumption has been that decisions should weigh in favor of maintaining life, and therefore, that it is the withdrawal rather than the continuation of ANH that requires particular justification. I will argue that this default position should be reversed. Instead, I will argue that the burden of justification lies with those who would continue artificial nutrition and hydration (ANH), and in the absence of knowledge as to the patient's advanced wishes, it is better to discontinue ANH. In particular, I will argue that among patients in PVS, there is not a compelling interest in being kept alive; that in general, we commit a worse violation of autonomy by continuing ANH when the patient's wishes are unknown; and that more likely than not, the maintenance of ANH as a bridge to a theoretical future time of recovery goes against the best interests of the patient.     

Modified tendon stripper for obtaining palmaris longus tendon graft

Tendon graft harvesting is a challenging part of hand surgery. It is not only a time-consuming procedure but also carries the potential complications associated with it. Various alternatives for this procedure are presented in the literature to overcome these difficulties. In this paper, we are presenting a series of cases in which a newly modified tendon stripper was used for tendon graft harvesting.     

Experimental artificial cultivation of corals from colony fragments

In 2010–2011, experimental commercial cultivation of 14 species of hermatypic corals was carried out using the method of donor colony fragmentation. The transplants successfully survived on experimental frame installations. The coral colonies that were recovered from the fragments became attached to the frame installations in a similar way to their attachment on natural substrata. After 1 year, the size of the trans-plants was found to have increased by 275%. The newly formed artificial coral community was colonized by the damselfish Dascyllus reticulates (Pomacentridae); the species is a common coral fish species that lives on natural reefs.     

丝裂霉素C预防肌腱粘连的实验研究

目的:探讨丝裂霉素C(mitomycin C,MMC)对肌腱粘连的影响.方法:SD大鼠80只,右足为丝裂霉素C组,左足为生理盐水组.以屈趾肌腱为试验对象,切断后采用改良Kessler法缝合.右足吻合处用0.4mg/ml MMC脑棉片湿敷5分钟,生理盐水反复冲洗3次;左足生理盐水脑棉片湿敷5分钟,生理盐水反复冲洗3次.术后1、2、4、8周处死动物,收集2组屈趾肌腱分别进行大体观察、组织学观察和羟脯氨酸含量测定.结果:丝裂霉素C组肌腱粘连程度较生理盐水组明显减轻,有统计学意义(P＜0.05),羟脯氨酸含量在术后2、4、8周较生理盐水组增高.结论:丝裂霉素C有防止肌腱粘连的作用.