We clarify the significance of quasiprobability (QP) in quantum mechanics that is relevant in describing physical quantities associated with a transition process. Our basic quantity is Aharonov's weak value, from which the QP can be defined up to a certain ambiguity parameterized by a complex number. Unlike the conventional probability, the QP allows us to treat two noncommuting observables consistently, and this is utilized to embed the QP in Bohmian mechanics such that its equivalence to quantum mechanics becomes more transparent. We also show that, with the help of the QP, Bohmian mechanics can be recognized as an ontological model with a certain type of contextuality

Quantum field theory is one of the most effective methods to treat the quantum manybody system. It has been applied to the quantum transport theory of material physics, such as localisation [l], the highly correlated electron system and the quantum hall effect [2,3,4]. The purpose of this paper is to apply quantum field theory to nanostructure devices for the numerical analysis of the quantum effects in them.We consider the action (1) for the electron-hole w system interacting with the phonon 4 and the random potential S. The Hamiltonian operator (2) is determined from the effective mass approximation.

We have developed PLEMO to assist hemiplegic stroke patients in upper-limb rehabilitation using a passive haptic device with electrorheological (ER) fluid brakes. The PLEMO has no moving parts, ensuring safe rehabilitation assistance in the clinical setting. The previously reported version of the PLEMO can determine the operating force and the displacement of the grip by using conventional sensor devices; however, it was not enough to provide information evaluating stroke patient motor function. To cover such shortcomings of the conventional systems, we developed a new grip and motor-functional evaluation software that detects synergy, a symptomatic feature in stroke patients. In clinical evaluation of 14 stroke patients - two Brunnstrom Recovery Stage III, three Stage IV, and nine Stage V - we studied the correlation between PLEMO evaluation and rehabilitation evaluation, and found a strong correlation between them, e.g., changes in wrist movement range and table-reaction force provided useful information on stroke severity.

Interlimb coordination involving cyclical movements of hand and foot in the sagittal plane is more difficult when the limbs move in opposite directions compared with the same direction (directional constraint). Here we first investigated whether the directional constraint on hand-foot coordination exists in motor imagery (imagined motion). Participants performed 10 cyclic coordinated movements of right wrist flexion-extension and right ankle dorsiflexion-plantarflexion as quickly and precisely as possible, in the following three conditions; (1) actual movements of the two limbs, (2) imaginary movements of the two limbs, and (3) actual movement of one limb combined with imaginary movement of the other limb. Each condition was performed under two directions; the same and the opposite direction. Task execution duration was measured as the time between the first and second press of a button by the participants. The opposite directional movement took a significantly longer time than did the same directional movement, irrespective of the condition type. This suggests that directional constraint of hand-foot coordination occurs even in motor imagery without actual motor commands or kinesthetic signals. We secondarily examined whether the corticospinal excitability of wrist muscles is modulated in synchronization with an imaginary foot movement to estimate the neural basis of directional constraint on imaginary hand-foot coordination. The corticospinal excitability of the forearm extensor in resting position increased during dorsiflexion and decreased during plantarflexion similarly in both actual and imaginary foot movements. This corticospinal modulation depending on imaginary movement phase likely produces the directional constraint on the imaginary hand-foot coordination.