Active self supplied AC-DC converter for piezoelectric energy scavenging systems with supply independent bias

Abstract- The paper focuses on an electronic interface which can be used into Piezoelectric Energy Scavenging Systems (PESS). These systems convert the energy of mechanical vibrations into electrical energy using a piezoelectric transducer to realize a power supply for low power electronic systems. To obtain a suitable supply source an AC-DC conversion of the output signal of these transducers is needed and, since the output power level of the energy scavenger can be very low, the conversion should be as efficient as possible. This paper shows an active voltage doubler AC-DC converter for PESSs. A novel driving circuitry topology is presented; it has the advantage to be tolerant with respect to the process variations. The converter uses exclusively a fraction of the harvested energy to supply itself and a bias circuit has been designed to make the total current consumption supply independent. The simulation results show that the efficiency of the AC-DC converter can be as high as 94%. The circuit will be diffused in 0.35µm CMOS STMicroelectronics technology. I

I give you a cup, I get a cup: a kinematic study on social intention.

While affordances have been intensively studied, the mechanisms according to how their activation is modulated by context are poorly understood. We investigated how the Agent׳s reach-to-grasp movement towards a target-object (e.g. a can) is influenced by the other׳s interaction with a second object (manipulative/functional) and by his/her eye-gaze communication. To manipulate physical context we showed participants two objects that could be linked by a spatial relation (e.g. can-knife, typically found in the same context), or by different functional relations. The functional relations could imply an action to perform with another person (functional-cooperative: e.g. can-glass), or on our own (functional-individual: e.g. can-straw). When objects were not related (e.g. can-toothbrush) participants had to refrain from responding. In order to respond, in the giving condition participants had to move the target object towards the other person, in the getting condition towards their own body. When participants (Agents) performed a reach-to-grasp movement to give the target object, in presence of eye-gaze communication they reached the wrist׳s acceleration peak faster if the Other previously interacted with the second object in accordance with its conventional use. Consistently participants reached faster the MFA when the objects were related by a functional-individual than a functional-cooperative relation. The Agent׳s getting response strongly affected the grasping component of the movement: in case of eye-gaze sharing, MFA was greater when the other previously performed a manipulative than a functional grip. Results reveal that humans have developed a sophisticated capability in detecting information from hand posture and eye-gaze, which are informative as to the Agent׳s intention

Predictors of cognitive impairment in advanced Parkinson's disease

Design: Retrospective cohort analysis. Methods: 100 patients with idiopathic Parkinson's disease were given a neuropsychological test battery investigating attention, memory, and visuospatial and executive functions. Test performance was compared against normative data, and linear regression determined significant predictors of cognitive impairment from a set of demographic and disease course variables. Results: Frontal-type cognitive dysfunction was widespread in patients with advanced Parkinson's disease. Attention and memory were mildly to moderately impaired, whereas visuospatial function showed only subtle impairment. Older age and tremor at onset were significant predictors of poor cognitive performance. Conclusions: The observed cognitive impairment in patients with advanced Parkinson's disease is more than expected for normal aging. Although in apparent contrast with most previous research, reporting a greater risk of cognitive dysfunction in Parkinson's disease patients with predominant akinesia/rigidity, tremor at onset may be a marker for more widespread brain pathology that contributes to an increased risk of cognitive impairment