This paper reports that for 200 years, the world has progressively lightened its energy diet by f... more This paper reports that for 200 years, the world has progressively lightened its energy diet by favoring hydrogen atoms over carbon in our hydrocarbon stew. The successful decarbonization of the energy system, the key to the alleviation of numerous environmental problems, will ultimately depend on the use of pure hydrogen fuel produced form sources and processes that are carbon-free. The outlook for aggregate reductions in the materials that an individual consumes, dematerialization, is less certain. Rapid evolution of the energy system along its current trajectory, combined with cultural change, can avert the environmental danger.danger.
Analysing environmental DNA (eDNA) in seawater can aid in monitoring marine fish populations. How... more Analysing environmental DNA (eDNA) in seawater can aid in monitoring marine fish populations. However, the extent to which current methods optimize fish eDNA detection from water samples is unknown. Here, we test modifications to laboratory components of an eDNA metabarcoding protocol targeting marine finfish. As compared to baseline methods, amplifying a smaller proportion of extracted DNA yielded fewer species, and, conversely, amplifying a larger proportion identified more taxa. Higher-read species were amplified more reproducibly and with less variation in read number than were lower-read species. Among pooled samples, 20-fold deeper sequencing recovered one additional fish species out of a total of 63 species. No benefit was observed with additional PCR cycles, alternative primer concentrations, or fish-selective primers. Experiments using an exogenous DNA standard to assess absolute eDNA concentration suggested that, for a given proportion of a DNA sample, current laboratory m...
This Working Paper develops a framework for the generation of integrated scenarios of carbon use ... more This Working Paper develops a framework for the generation of integrated scenarios of carbon use and climatic impacts in the computer-based game and for strengthening the design of the board in the board game. The paper also seeks the assistance of readers in the further elaboration of several aspects of game design.
Gordon Moore famously observed that the number of transistors in state-of-the-art integrated circ... more Gordon Moore famously observed that the number of transistors in state-of-the-art integrated circuits (units per chip) increases exponentially, doubling every 12–24 months. Analysts have debated whether simple exponential growth describes the dynamics of computer processor evolution. We note that the increase encompasses two related phenomena, integration of larger numbers of transistors and transistor miniaturization. Growth in the number of transistors per unit area, or chip density, allows examination of the evolution with a single measure. Density of Intel processors between 1959 and 2013 are consistent with a biphasic sigmoidal curve with characteristic times of 9.5 years. During each stage, transistor density increased at least tenfold within approximately six years, followed by at least three years with negligible growth rates. The six waves of transistor density increase account for and give insight into the underlying processes driving advances in processor manufacturing an...
This paper reports that for 200 years, the world has progressively lightened its energy diet by f... more This paper reports that for 200 years, the world has progressively lightened its energy diet by favoring hydrogen atoms over carbon in our hydrocarbon stew. The successful decarbonization of the energy system, the key to the alleviation of numerous environmental problems, will ultimately depend on the use of pure hydrogen fuel produced form sources and processes that are carbon-free. The outlook for aggregate reductions in the materials that an individual consumes, dematerialization, is less certain. Rapid evolution of the energy system along its current trajectory, combined with cultural change, can avert the environmental danger.danger.
Analysing environmental DNA (eDNA) in seawater can aid in monitoring marine fish populations. How... more Analysing environmental DNA (eDNA) in seawater can aid in monitoring marine fish populations. However, the extent to which current methods optimize fish eDNA detection from water samples is unknown. Here, we test modifications to laboratory components of an eDNA metabarcoding protocol targeting marine finfish. As compared to baseline methods, amplifying a smaller proportion of extracted DNA yielded fewer species, and, conversely, amplifying a larger proportion identified more taxa. Higher-read species were amplified more reproducibly and with less variation in read number than were lower-read species. Among pooled samples, 20-fold deeper sequencing recovered one additional fish species out of a total of 63 species. No benefit was observed with additional PCR cycles, alternative primer concentrations, or fish-selective primers. Experiments using an exogenous DNA standard to assess absolute eDNA concentration suggested that, for a given proportion of a DNA sample, current laboratory m...
This Working Paper develops a framework for the generation of integrated scenarios of carbon use ... more This Working Paper develops a framework for the generation of integrated scenarios of carbon use and climatic impacts in the computer-based game and for strengthening the design of the board in the board game. The paper also seeks the assistance of readers in the further elaboration of several aspects of game design.
Gordon Moore famously observed that the number of transistors in state-of-the-art integrated circ... more Gordon Moore famously observed that the number of transistors in state-of-the-art integrated circuits (units per chip) increases exponentially, doubling every 12–24 months. Analysts have debated whether simple exponential growth describes the dynamics of computer processor evolution. We note that the increase encompasses two related phenomena, integration of larger numbers of transistors and transistor miniaturization. Growth in the number of transistors per unit area, or chip density, allows examination of the evolution with a single measure. Density of Intel processors between 1959 and 2013 are consistent with a biphasic sigmoidal curve with characteristic times of 9.5 years. During each stage, transistor density increased at least tenfold within approximately six years, followed by at least three years with negligible growth rates. The six waves of transistor density increase account for and give insight into the underlying processes driving advances in processor manufacturing an...
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