PROGRESS IN ESTIMATING THE MARGINAL COSTS OF GREENHOUSE GAS EMISSIONS

The unjust distributional consequences of climate change, and its potentially negative aggregate effect on economic growth and welfare are two reasons to be concerned about climate change. Our knowledge of the impact of climate change is incomplete. Monetary valuation is difficult and controversial. The effect of other developments on the impacts of climate change is largely speculative. Nonetheless, it can be shown that poorer countries and people are more vulnerable than are richer countries and people. A modest global warming is likely to have a net negative effect on poor economics in hot climates, but may have a positive effect on rich economies in temperate climates. If one counts dollars, the world aggregate impact may be positive. If one counts people, the world aggregate effect is probably negative. For more substantial warming, negative effects become more negative, and positive effects turn negative. The marginal costs of carbon dioxide emissions are uncertain and sensitive to assumptions that partially reflect ethical and methodological positions, but are unlikely to exceed $50 per tonne of carbon. The marginal costs of methane emission are likely to be less than$250/tCH4; the marginal costs of nitrous oxide emissions are probably lower than $7000/tN2O. Global warming potentials, the official manner to trade-off the various greenhouse gases, do not reflect, conceptually or numerically, the real tradeoffs in either a cost-benefit or a cost-effectiveness framework.Impacts of climate change, economic valuation, equity, marginal costs

Altering Parameters of CRISPR/Cas9 Mediated Genome Editing in Escherichia coli Helps Identify Sources of Variation in Editing Efficiency

CRISPR/Cas9, originating from a bacterial immune system, has been identified as a powerful tool for genome modification (Jinek, et al., 2012). Historically, analyzing genotype-phenotype relationships have been limited by DNA synthesis and sequencing technology. Recent developments in genome editing (CRISPR/Cas9) coupled to improvements in synthesis and sequencing allows mapping these relationships at an entirely new scale. A technique novel to the Gill lab for genome modification that harnesses the CRISPR-Cas system is “CRISPR Enabled Trackable Genomic Engineering” or “CREATE” technology. CREATE technology is one such strategy for simultaneously making hundreds of thousands of single genomic edits, then tracking the resultant phenotypes. In this study, I alter parameters of the CREATE mechanism to elucidate the cause of variability in editing efficiency between different editing constructs. I demonstrate that editing efficiency is impacted by guide RNA toxicity, genomic position, expression levels of Cas9, availability of template for homologous recombination, and expression levels of phage-based recombination proteins. I find that high toxicity is related to high editing efficiency. The position of the gene being edited in the bacterial genome impacts editing efficiency in a pattern dependent on guide toxicity. Expression levels of Cas9 also affect editing efficiency in a guide toxicity-dependent fashion. Additional results studying recombination suggest increasing intracellular abundance of donor DNA can lead to increased editing efficiency, in a genomic position-specific manner. A final finding was that expressing recombination proteins using a constitutive promoter replicated the behavior of the traditional lambda Red expression system, opening up possibilities for future modifications

National Nuclear Security Administration Nonproliferation Graduate Fellowship Program Annual Report in Brief: October 2007 - May 2008

This abbreviated Annual Report covers program activities of the National Nuclear Security Administration (NNSA) Nonproliferation Graduate Fellowship Program (NGFP) from October 2007 through May 2008--the timeframe between the last Annual Report (which covered activities through September 2007) and the next report (which will begin with June 2008 activities). In that timeframe, the NGFP continued building a solid foundation as the program began reaping the benefits of recently implemented changes. This report is organized by Fellowship class and the pertinent program activities for each, including: October 2007 Recruiting events and final applications (Class of 2008) Winter 2007 Selection and hiring (Class of 2008) Spring 2008 Career development roundtables (Class of 2007) Orientation planning (Class of 2008) Recruitment planning and university outreach (Class of 2009) May 2008 Closing ceremony (Class of 2007

The key physical parameters governing frictional dissipation in a precipitating atmosphere

Precipitation generates small-scale turbulent air flows the energy of which ultimately dissipates to heat. The power of this process has previously been estimated to be around 2-4 W m-2 in the tropics: a value comparable in magnitude to the dynamic power of the global circulation. Here we suggest that this previous power estimate is approximately double the true figure. Our result reflects a revised evaluation of the mean precipitation path length Hp. We investigate the dependence of Hp on surface temperature,relative humidity,temperature lapse rate and degree of condensation in the ascending air. We find that the degree of condensation,defined as the relative change of the saturated water vapor mixing ratio in the region of condensation, is a major factor determining Hp. We estimate from theory that the mean large-scale rate of frictional dissipation associated with total precipitation in the tropics lies between 1 and 2 W m-2 and show that our estimate is supported by empirical evidence. We show that under terrestrial conditions frictional dissipation constitutes a minor fraction of the dynamic power of condensation-induced atmospheric circulation,which is estimated to be at least 2.5 times larger. However,because Hp increases with surface temperature Ts, the rate of frictional dissipation would exceed that of condensation-induced dynamics, and thus block major circulation, at Ts >~320 K in a moist adiabatic atmosphere.Comment: 12 pp, 2 figure