1,479 research outputs found
Politics and Economics of Second-Best Regulation of Greenhouse Gases: The Importance of Regulatory Credibility
Modellers have examined a wide array of ideal-world scenarios for regulation of greenhouse gases. In this ideal world, all countries limit emissions from all economic sectors; regulations are implemented by intelligent, well-informed forward-looking agents; all abatement options, such as new energy technologies and forestry offsets, are available; trade in goods, services and emission credits is free and unfettered. Here we systematically explore more plausible second-best worlds. While analysts have given inordinate attention to which countries participate in regulation—what we call “variable geometry”—which has a strikingly small impact on total world cost of carbon regulations if international trade in emission credits allows economies to equilibrate. Limits on emission trading raise those costs, but by a much smaller amount than expected because even modest amounts of emission trading (less than 15% of abatement in a plausible scenario that varies the geometry of effort) have a large cost-reducing impact. Second best scenarios that see one sector regulated more aggressively and rapidly than others do not impose much extra burden when compared with optimal all-sector scenarios provided that regulations begin in the power sector. Indeed, some forms of trade regulation might decrease the financial flows associated to a carbon policy thus increasing political feasibility of the climate agreement. Much more important than variable geometry, trading and sectors is another factor that analysts have largely ignored: credibility. In the real world governments find it difficult to craft and implement credible international regulations and thus agents are unable to be so forward-looking as assumed in ideal-world modelling exercises. As credibility declines the cost of coordinated international regulation skyrockets—even in developing countries that are likely to delay their adoption of binding limits on emissions. Because international institutions such as treaties are usually weak, governments must rely on their own actions to boost regulatory credibility—for example, governments might “pre-commit” international regulations into domestic law before international negotiations are finally settled, thus boosting credibility. In our scenarios, China alone would be a net beneficiary of pre-commitment that advances its carbon limits two decades (from 2030, in our scenario, to today) if doing so would make international regulations more credible and thus encourage Chinese firms to invest with a clearer eye to the future. Overall, low credibility is up to 6 times more important in driving higher world costs for carbon regulations when compared with variable geometry, limits on emission trading and variable sectors. In this paper, we have not explored the other major dimension to the second-best: the lack of timely availability of the full range of abatement options, although our results suggest that even this will be less consequential than credibility.Greenhouse Gases, Second-best Regulation
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International Workshop on Research, Development, and Demonstration to Enhance the Role of Nuclear Energy in Meeting Climate and Energy Challenges
Dramatic growth in nuclear energy would be required for nuclear power to provide a significant part of the carbon-free energy the world is likely to need in the 21st century, or a major part in meeting other energy challenges. This would require increased support from governments, utilities, and publics around the world. Achieving that support is likely to require improved economics and major progress toward resolving issues of nuclear safety, proliferation-resistance, and nuclear waste management. This is likely to require both research, development, and demonstration (RD&D) of improved technologies and new policy approaches.
To gather information on the RD&D needs for the future of nuclear energy, the future cost and performance of nuclear technologies, and on the major barriers to large-scale deployment of nuclear energy, a team of researchers at Harvard University and the Fondazione Eni Enrico Mattei (FEEM) conducted two coordinated surveys of nuclear experts. The surveys asked experts how much they would recommend that their governments spend on nuclear energy RD&D; what progress in cost and performance might be expected by 2030 if those recommendations were followed; and what other factors might constrain or promote future nuclear energy growth. Leading experts from the United States (U.S.) and the European Union (E.U.) participated in this expert elicitation surveys during the summer and fall of 2010. In April 2011, the FEEM and Harvard teams held a workshop in Venice, Italy with a subset of the participating E.U. and U.S. experts to present and discuss the results of the elicitations, in an effort to understand where there is consensus and where the most important disputes and uncertainties lie. Given the Fukushima nuclear accident in Japan, the meeting opened with a discussion of the significance of that event for the future of nuclear power, and of the main lessons learned
Impact of palliative care in evaluating and relieving symptoms in patients with advanced cancer. Results from the demetra study
Background: Cancer patients experience multiple symptoms throughout the course of the disease. We aimed to provide a comprehensive analysis of the symptom burden in patients with advanced cancer at admission to specialist palliative care (PC) services and seven days later to estimate the immediate impact of PC intervention. Patient and methods: The analysis was based on an observational, prospective, multicenter study (named DEMETRA) conducted in Italy on new patients accessing network specialist PC centers during the period May 2017–November 2017. The prevalence and intensity of symptoms were assessed at baseline and after seven days using three tools including the Edmonton Symptom Assessment System (ESAS). Results: Five PC centers recruited 865 cancer patients. Thirty-three different symptoms were observed at the baseline, the most frequent being asthenia (84.9%) and poor well-being (71%). The intensity of the most frequent symptoms according to ESAS ranged from 5.5 for asthenia to 3.9 for nausea. The presence and intensity of physical symptoms increased with increasing levels of anxiety and depression. After seven days, prevalence of nausea and breathlessness as well as intensity of almost all symptoms significantly decreased. Conclusions: The study confirmed the considerable symptom burden of patients with advanced cancer. PC intervention has significantly reduced the severity of symptoms, despite the patients’ advanced disease and short survival
Sustainable Hydrogen Production via Sorption Enhanced Reforming of Complex Biorefinery Side Streams in a Fixed Bed Adiabatic Reactor
In this work, sorption enhanced steam reforming is explored as a potential solution for the valorization of gaseous streams recovered from biorefinery hydrogenation processes. The hydrogen content of such streams limits the hydrocarbon conversion in conventional steam reforming due to thermodynamic and kinetic constraints. A previously developed 1D dynamic heterogeneous model of an adiabatic reactor was thus applied to evaluate the effect of H-2 dilution on the performance indicators of the sorption enhanced reforming process. The mathematical model analysis highlights that despite of CO2 capture by the sorbent favorably modifies the thermodynamics of syngas production, H-2 dilution worsens the performance of the sorption enhanced reforming of model H-2/CH4 streams with respect to pure CH4. Results show a drop of 17% for CH4 conversion and a reduction of 15.4% of the captured CO2 on passing from pure methane to a H-2/CH4 feed with a 40/60 molar ratio. However, on increasing the heat capacity of the bed, by replacing part of the sorbent with an inert heat carrier, better performances are calculated for the H-2/CH4 feed matching the pure CH4 case. The presence of C2+ hydrocarbons is assessed as well and the results show a significant improvement in the reformer's performance; in the case of a stream composed of H-2/CH4/C3H8 with a molar ratio 40/45/15, the total hydrocarbon conversion grows to 92.8%, CO2 capture ratio to 82.6%, and H-2 purity to 95.6%. The positive effect is associated with thermal factors that promote the reaction kinetics. Thus, the suitability of the sorption enhanced reforming technology to H-2-rich and C-poor streams is strictly composition dependent; by cofeeding of C2+ hydrocarbons, the process turns into a remarkable solution for converting gaseous streams in pure H-2
Time-reversed symmetry and covariant Lyapunov vectors for simple particle models in and out of thermal equilibrium
Recently, a new algorithm for the computation of covariant Lyapunov vectors
and of corresponding local Lyapunov exponents has become available. Here we
study the properties of these still unfamiliar quantities for a number of
simple models, including an harmonic oscillator coupled to a thermal gradient
with a two-stage thermostat, which leaves the system ergodic and fully time
reversible. We explicitly demonstrate how time-reversal invariance affects the
perturbation vectors in tangent space and the associated local Lyapunov
exponents. We also find that the local covariant exponents vary discontinuously
along directions transverse to the phase flow.Comment: 13 pages, 11 figures submitted to Physical Review E, 201
Differential gene expression patterns in cyclooxygenase-1 and cyclooxygenase-2 deficient mouse brain
BACKGROUND: Cyclooxygenase (COX)-1 and COX-2 produce prostanoids from arachidonic acid and are thought to have important yet distinct roles in normal brain function. Deletion of COX-1 or COX-2 results in profound differences both in brain levels of prostaglandin E(2 )and in activation of the transcription factor nuclear factor-κB, suggesting that COX-1 and COX-2 play distinct roles in brain arachidonic acid metabolism and regulation of gene expression. To further elucidate the role of COX isoforms in the regulation of the brain transcriptome, microarray analysis of gene expression in the cerebral cortex and hippocampus of mice deficient in COX-1 (COX-1(-/-)) or COX-2 (COX-2(-/-)) was performed. RESULTS: A majority (>93%) of the differentially expressed genes in both the cortex and hippocampus were altered in one COX isoform knockout mouse but not the other. The major gene function affected in all genotype comparisons was 'transcriptional regulation'. Distinct biologic and metabolic pathways that were altered in COX(-/- )mice included β oxidation, methionine metabolism, janus kinase signaling, and GABAergic neurotransmission. CONCLUSION: Our findings suggest that COX-1 and COX-2 differentially modulate brain gene expression. Because certain anti-inflammatory and analgesic treatments are based on inhibition of COX activity, the specific alterations observed in this study further our understanding of the relationship of COX-1 and COX-2 with signaling pathways in brain and of the therapeutic and toxicologic consequences of COX inhibition
Local Gram-Schmidt and Covariant Lyapunov Vectors and Exponents for Three Harmonic Oscillator Problems
We compare the Gram-Schmidt and covariant phase-space-basis-vector
descriptions for three time-reversible harmonic oscillator problems, in two,
three, and four phase-space dimensions respectively. The two-dimensional
problem can be solved analytically. The three-dimensional and four-dimensional
problems studied here are simultaneously chaotic, time-reversible, and
dissipative. Our treatment is intended to be pedagogical, for publication in
Communications in Nonlinear Science and Numerical Computation and for use in an
updated version of our book on Time Reversibility, Computer Simulation, and
Chaos. Comments are very welcome.Comment: 25 pages with 12 figures; New Figures 9-12 based on two billion
timesteps rather than the two hundred million used in Version 1; Electronic
publication in Communications in Nonlinear Science and Numerical Computation
scheduled for 1 July 201
Modeling Uncertainty in Climate Change: A Multi-Model Comparison
The economics of climate change involves a vast array of uncertainties, complicating both the analysis and development of climate policy. This study presents the results of the first comprehensive study of uncertainty in climate change using multiple integrated assessment models. The study looks at model and parametric uncertainties for population, total factor productivity, and climate sensitivity. It estimates the pdfs of key output variables, including CO2 concentrations, temperature, damages, and the social cost of carbon (SCC). One key finding is that parametric uncertainty is more important than uncertainty in model structure. Our resulting pdfs also provide insights on tail events
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