抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

The usefulness and versatility of a robotic end-effector depends on the diversity of grasps it can accomplish and also on the complexity of the control methods required to achieve them. We believe that soft hands are able to provide diverse and robust grasping with low control complexity. They possess many mechanical degrees of freedom and are able to implement complex deformations. At the same time, due to the inherent compliance of soft materials, only very few of these mechanical degrees have to be controlled explicitly. Soft hands therefore may combine the best of both worlds. In this paper, we present RBO Hand 2, a highly compliant, underactuated, robust, and dexterous anthropomorphic hand. The hand is inexpensive to manufacture and the morphology can easily be adapted to specific applications. To enable efficient hand design, we derive and evaluate computational models for the mechanical properties of the hand's basic building blocks, called PneuFlex actuators. The versatility of RBO Hand 2 is evaluated by implementing the comprehensive Feix taxonomy of human grasps. The manipulator's capabilities and limits are demonstrated using the Kapandji test and grasping experiments with a variety of objects of varying weight. Furthermore, we demonstrate that the effective dimensionality of grasp postures exceeds the dimensionality of the actuation signals, illustrating that complex grasping behavior can be achieved with relatively simple control.

/pdf/a-novel-type-of-compliant-and-underactuated-robotic-hand-for-28trfw7f6g.pdf

A novel type of compliant and underactuated robotic hand for dexterous grasping

The existing shortage of therapists and caregivers assisting physically disabled individuals at home is expected to increase and become serious problem in the near future The patient population needing physical rehabilitation of the upper extremity is also constantly increasing Robotic devices have the potential to address this problem as noted by the results of recent research studies However, the availability of these devices in clinical settings is limited, leaving plenty of room for improvement The purpose of this paper is to document a review of robotic devices for upper limb rehabilitation including those in developing phase in order to provide a comprehensive reference about existing solutions and facilitate the development of new and improved devices In particular the following issues are discussed: application field, target group, type of assistance, mechanical design, control strategy and clinical evaluation This paper also includes a comprehensive, tabulated comparison of technical solutions implemented in various systems

/pdf/a-survey-on-robotic-devices-for-upper-limb-rehabilitation-3ykq953s17.pdf

A survey on robotic devices for upper limb rehabilitation

The existing shortage of therapists and caregivers assisting physically disabled individuals at home is expected to increase and become serious problem in the near future. The patient population needing physical rehabilitation of the upper extremity is also constantly increasing. Robotic devices have the potential to address this problem as noted by the results of recent research studies. However, the availability of these devices in clinical settings is limited, leaving plenty of room for improvement. The purpose of this paper is to document a review of robotic devices for upper limb rehabilitation including those in developing phase in order to provide a comprehensive reference about existing solutions and facilitate the development of new and improved devices. In particular the following issues are discussed: application field, target group, type of assistance, mechanical design, control strategy and clinical evaluation. This paper also includes a comprehensive, tabulated comparison of technical solutions implemented in various systems.

A survey on robotic devices for upper limb

In this paper a very lightweight artificial hand is presented that approximates the manipulation abilities of a human hand very well. A large variety of different objects can be grasped reliably and the movements of the hand appear to be very natural. This five finger hand has 13 independent degrees of freedom driven by a new type of powerful small size flexible fluidic actuator. The actuators are completely integrated in the fingers which made possible the design of a very compact and lightweight hand that can either be used as a prosthetic hand or as a humanoid robot hand. A mathematical model for the expansion of a flexible fluidic actuator is given and the mechanical construction and features of the new anthropomorphic hand are illustrated.

A new ultralight anthropomorphic hand

Indications for laparoscopic interventions are constantly expanding, and currently the standard for an increasing number of operations is minimally invasive surgery (MIS). This means that surgeons in training have to learn laparoscopic techniques, having never performed the procedure in the conventional way. MIS demands psychomotor skills that are not required in conventional surgery, such as hand–eye coordination within a 3-dimensional scene seen on a 2-dimensional monitor. Moreover, traditional surgical training in which a learning surgeon performs parts of an operation guided by an experienced surgeon is hardly applicable in MIS.

The introduction of MIS was initially associated with a high complication rate.1,2 The term “learning curve” was introduced to surgery to refer to the number of operations a surgeon has to perform to reach an experience level with a low complication rate.3 Depending on the type of operation, 15 to 100 procedures are required to reach the plateau of this learning curve.4–6 Further studies showed that even experienced laparoscopic surgeons had to go through a learning curve again when they learned new laparoscopic techniques or used new instruments.7 This led to the development of special training programs, which are associated with certain problems. More realistic training usually involves training on animals, which is elaborate, expensive, and not available to many surgeons. Moreover, this training does not include pathologic situations and anatomic variations, and thus, does not allow specific training for difficult situations.

Basic training is carried out on conventional video training devices (CVT) using mechanical models. This training is inexpensive and readily available but not realistic. To overcome these problems, virtual reality (VR) trainers were developed that offer several advantages: permanent availability, training of specific skills, more or less realistic surgical scenarios, assessment of trainees, etc. Recent improvements in computer technology made the construction of advanced simulators possible, and a number of companies are now offering VR-trainers.

The increasing economic orientation of medicine in conjunction with shorter training schedules underscores the importance of specific training programs. This is especially true for MIS because of its special requirements. Despite the importance of training for MIS, there is little scientific knowledge about the learning mechanisms involved in acquiring laparoscopic skills and the methods suitable for training.8 Conventional laparoscopic training aims to overcome these problems by providing realistic training conditions using laparoscopic instruments in mechanical models. Basic and advanced tasks are chosen based on empirical considerations. As soon as the trainee has reached a certain level of expertise, the training is continued in animal models, which are assumed to provide the most realistic training conditions.

VR-trainers are likely to be an integral part of MIS training in the near future. It is therefore essential to know whether a simulator can provide a training environment that is suitable to improve surgical skills. Several studies have recently been conducted that document learning curves and training improvement with simulators.9–14 However, the important question remains whether skills acquired during simulator training can be transferred to a real situation. There are few studies on this topic, and they do not provide uniform results.15–18

Virtual laparoscopy simulators aim to resemble real instrument handling and object interactions. The degree of physical realism of the simulation varies depending on the hardware and software capabilities of a simulator. Because of limited computing power, a simulator can only represent a part of physical reality. This means that certain limitations have to be accepted for any simulation, eg, simplified surfaces of objects or organs, simplified or no haptic feedback, limited visual details, etc. The decision as to which part of reality should be simulated is based on assumptions about how laparoscopic skills are acquired and which parts of physical reality are important for successful training. Currently, there is little scientific evidence to prove that these assumptions are correct. The study of Seymour et al impressively showed that the MIST VR simulator could improve operating room performance.19 Although this study examined the training success of a VR-simulator in general, it has not yet been thoroughly validated whether a specific simulator design and specific tasks represent the reality that is needed to train laparoscopic skills. The rapid technical development and increasing availability of simulators necessitates methods to validate whether a VR-trainer provides a suitable environment for MIS training and whether the acquired skills can be transferred to real situations. The aim of this study was to compare a VR-trainer with a physically realistic environment. For the purpose of this study, a CVT served as the counterpart. The study design included specific training tasks that were identically constructed for the VR-trainer and the CVT. In doing so, we were able to directly compare the computer trainer, which is based on virtual reality, with the conventional trainer, which is based on physical reality. The chosen tasks were part of the basic skills training program and included instrument and camera manipulation.

We postulated 3 hypotheses for the current study: 1) Training results in conventional and VR-training are comparable. 2) Skills acquired on the VR-simulator are transferable to the physically realistic environment of a conventional video trainer. 3) Laparoscopically experienced surgeons perform better than novices in conventional and VR-simulator training.

A prospective randomized study to test the transfer of basic psychomotor skills from virtual reality to physical reality in a comparable training setting.

This paper presents the new robotic FRH-4 hand. The FRH-4 hand constitutes a new hybrid concept of an anthropomorphic five fingered hand and a three jaw robotic gripper. The hand has a humanoid appearance while maintaining the precision of a robotic gripper. Since it is actuated with flexible fluidic actuators, it exhibits an excellent power to weight ratio. These elastic actuators also ensure that the hand is safe for interacting with humans. In order to fully control the joints, it is equipped with position sensors on all of the 11 joints. The hand is also fitted with tactile sensors based on cursor navigation sensor elements, which allows it to have grasping feedback and the ability for exploration.

A new anthropomorphic robotic hand

A new experimental hand prosthesis design is presented that differs from that of conventional prostheses. With the objective of addressing consumers' requirements, functionality was increased and cosmetic appearance became more natural. By integrating a hydraulic system with 8 small fluidic actuators at the digit joints, different important grasping patterns of everyday life can be performed. These are: power grasp, hook grasp, precision grasp, lateral pinch, and a posture to operate a keyboard with the extended index. As a result of multi-articulation and the inherent compliancy of the actuators, objects can be grasped adaptively. Moreover, a vibrotactile feedback system makes the prosthesis controllable without visual attention. For a more natural appearance, the hand is covered by a cosmetic silicone rubber glove. The hands are designed for performing activities of everyday life, including office work. The new hand design can help closing the gap between purely cosmetic hands and functional hands.

Georg Bretthauer

Papers

A new ultralight anthropomorphic hand

A prospective randomized study to test the transfer of basic psychomotor skills from virtual reality to physical reality in a comparable training setting.

A new anthropomorphic robotic hand

Progress in the development of a multifunctional hand prosthesis

Automated feature assessment in instrumented gait analysis