Suchergebnisse

Visuelle Prothesen sollen das Sehvermögen von erblindeten Menschen wiederherstellen. Dies ist mit zertifizierten Sehprothesen bereits in eingeschränktem Rahmen möglich, aber für eine räumliche Wahrnehmung durch elektrisch aktivierte Zellen werden signifikante Verbesserungen benötigt. Es werden Anordnungen von Neuronen in der Retina modelliert, um Konzepte für eine Verbesserung der visuellen Wahrnehmung zu entwickeln. Neurologische Modelle und theoretische Überlegungen für eine physikalische Realisierung der Elektronik werden in die Untersuchungen einbezogen und Modellrechnungen zur Erhöhung der Elektrodenanzahl, zur Bestimmung der sicheren Stimulations¬bereiche und zur pixelweisen Stimulation vorgestellt. Weiterhin werden physikalischen Aspekte von Phosphenen diskutiert. Die Modellrechnungen werden mit Hilfe von experimentellen Ergebnissen aus der Literatur verifiziert. ; Visual prosthesis aims to restore vision to those affected by sight-robbing illnesses. Although government-approved vision devices provide advantageous sight enhancements, visual and spatial perception of electrically activated cells requires significant improvement for delivering functional vision. High-level theoretical studies of electrode arrangements and of realistic neural responses in the retina are modeled for enhancing visual perception. Computational efficiency in neural modeling and deep theoretical thinking for a possible physical realization of electronics are considered. The theoretical viability of increasing electrode sites, safe avenues of stimulation that guarantee electrochemical safety and pixel-wise stimulation are met. The understanding of the physical aspects of phosphenes is addressed. Neural modeling is verified by means of experimental studies from literature.

Top-down approaches to reducing global carbon dioxide emissions have so far met with limited success, even though most countries accept the urgency of mitigating climate change and have entered into various agreements that should help reduce emissions. This article does not dismiss the importance of such "top-down" agreements for developing rational strategies to achieve declining total emissions, but it suggests a complementary approach to encourage immediate "bottom-up" progress on climate goals that do not need to wait for global cooperation. This paper develops a framework to identify free-riding behavior among countries that use three readily measured parameters of the country's economy: carbon intensity, rate of change of the carbon intensity, and per capita GDP. It then goes on to propose a simple formula to calculate trade sanctions against a free-riding country that could be used in bilateral actions to incentivize carbon emissions reductions. The paper argues that the value of the goods, the difference in carbon intensity between the importer and exporter, and the cost of carbon removal can be used to calculate the unfair trade advantage of a free-riding country. The dynamics of the proposed framework are tested through three case studies, highlighting current free-rider behavior - based on historic emissions for the period 1991-2012; an lternate, hypothetical scenario whereby a subset of countries follow aggressive carbon emission reductions; and a 450 ppm stabilization scenario.