Energy harvesting is becoming popular for small systems such as micro-sensors or medical implantable devices, which may not need or be able to include large energy storage devices. However power from energy harvesting circuits may be very limited and vary within a large range. Therefore an on-chip intelligent and flexible power delivery method bypassing external energy storage devices and corresponding charging circuits may be advantageous. Also, different computation loads may tolerate different degrees of variance in the supplied VDD. Thus, a hybrid power delivery method fully behaving as switched capacitor dc-dc converter or capacitor bank block to generate stable or variable power supply is developed to cope with variable harvested energy. The method is verified by hardware, which has been employed for VLSI chip testing. It can be considered as a valuable reference for later on-chip fabrication and task & power scheduling research.
Frog skin was mounted in an Ussing chamber and the actions of caerulein, gastrin, pentagastrin, and secretin on the active transport of sodium were studied using the short-circuit current method. All polypeptides exerted their effect when placed in the solution bathing the outside surface of the skin. The response was a transient dose-related increase in the transepithelial electrical potential difference and in the short-circuit current. Analysis of the response indicated that at submaximal doses the effect was due to an increase in the rate of entry of sodium through the outer barrier to active sodium transport. At supramaximal doses the passive permeability of the skin was also increased. Th ED50 concentrations of the hormones were: caerulein, 50 pM; gastrin, 53 pM; pentagastrin, 440 pM; and secretin, 30 pM. It is argued that the large quantity of caerulein or caerulein-like peptides stored in the skin may be required either to control the entry of sodium when the amphibian is undergoing maximum stress in a freshwater environment, or that it may have a protective function for the amphibian as it could elicit a noxious hypersecretion in the gastrointestinal tract of the predator together with a marked hypotension.
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