This paper presents the design, development, and experimental characterization of a 24channel programmable charge-balanced current-mode neurostimulator IC. Each channel is equipped with a quad-threshold voltage-based charge imbalance detection and a dedicated hybrid preventive-detective charge balancing circuit. The interplay of the preventive and detective control loops utilized for charge balancing has resulted in minimizing the power and timing overhead of the proposed strategy for maintaining a charge-neutral electrode-tissue interface, while avoiding the risk of unintended stimulation. The design offers dynamic programmability for the safe and unsafe charge imbalance thresholds, as well as for the balancing speed and precision. The IC is fabricated in a standard 0.18µm CMOS technology with an overall active area of 2.27mm 2 . Experimental characterization results of different circuit blocks are presented and discussed. Additionally, the IC's efficacy in conducting charge-balanced stimulation is experimentally validated under various scenarios and for the full range of stimulation current magnitude, showing the balancing accuracy, latency, and active time. Experiments are conducted both with a simplified electrical model of the interface impedance as well as in vitro. Compared to the state-of-the-art stimulators with a closed-loop charge balancer, the presented work offers the most energy-efficient charge balancing technique, the shortest required inter-pulse interval (i.e., neutralization time), and the highest balancing precision.INDEX TERMS Charge balancing, neurostimulator, implantable IC, neural interface, energy-efficient design, closed-loop control, VNS, electrical current-mode stimulation.
Forests remain an important resource in Iran, as most of the livelihood activities of local communities, especially in the semi-arid environment of the Zagros forests, are dependent on forest resources. The aim of this study was to identify the type and extent of forest dependency. Semi-structured interviews and questionnaires were used to collect data from 170 households in Central Zagros. Results show that using firewood for fuel and non-fuel uses, harvesting edible and medicinal plants, agriculture and horticulture, and livestock grazing were the main forest livelihood activities undertaken by the households in the study area. On average, each household harvested 18.08 cubic meters of oak per year for water heating (bathing), baking bread, heating, cooking, heating milk and buttermilk, agricultural tools, house building, warehouses and shelters, fencing, branches for livestock, charcoal and harvesting firewood for sale. Of rural households, 72% used edible plants, and 86% used medicinal plants. Age, job, residence status, number of livestock, crop farming and household size were found to be correlated with forest dependency. Findings from this study contribute broadly to an integrated understanding of the bio-human dimensions of forest ecosystems, with specific reference to the study area.
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