1,941 research outputs found

    Editorial review essay

    Get PDF

    The Value of Emissions Trading

    Get PDF
    Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).This paper estimates the value of international emissions trading, focusing attention on a here-to-fore neglected component: its value as a hedge against uncertainty. Much analysis has been done of the Kyoto Protocol and other potential international greenhouse gas mitigation policies comparing the costs of achieving greenhouse gas emission targets with and without trading. These studies often show large cost reductions for all Parties under trading compared to a no trading case. We investigate the welfare gains of including emissions trading in the presence of uncertainty in economic growth rates, using both a partial equilibrium model based on marginal abatement cost curves and a computable general equilibrium model that allows consideration of the interaction of emissions trading with existing energy taxes and changes in terms of trade. We find that the hedge value of international trading is small relative to its value in reallocating emissions reductions when, as in the Kyoto Protocol, the burden-sharing scheme does not resemble a least-cost allocation. The Kyoto Protocol also allocated excess allowances to Russia, so-called “hot air,” and much of the value often attributed to emissions trading stems from other Parties having access to these extra allowances, which has the effect of lowering the aggregate emissions target. We also find that the effects of preexisting tax distortions and terms of trade dominate the hedge value of trading. We conclude that the primary value of emissions trading in international agreements is as a burden-sharing or wealth transfer mechanism and should be judged accordingly.We gratefully acknowledge helpful comments from A.D. Ellerman. This research was supported by the US Department of Energy (DE-FG02-02ER63468, DE-FG04-04ER63929), US Environmental Protection Agency, US National Science Foundation, US National Aeronautics and Space Administration, US National Oceanographic and Atmospheric Administration; and the Industry and Foundation Sponsors of the MIT Joint Program on the Science and Policy of Global Change

    Peptide synthesis by recombinant Fasciola hepatica cathepsin L1

    Get PDF
    Synthesis of the tripeptide Z-Phe-Arg-SerNH2 has been accomplished by a recombinant cysteine protease, cathepsin L1 from liver fluke (Fasciola hepatica), using Z-Phe-Arg-OMe as acyl acceptor and SerNH2 as nucleophile in 0.1 M ammonium acetate pH 9.0–12.5% v/v acetonitrile at 37 °C. LC–MS detection indicated tripeptide formation after 10 min, continuing up to 5.5 h. The ester Z-Phe-Arg-OMe was detected throughout the experiment but the hydrolysis product Z-Phe-Arg-OH appeared early and in quite large amounts. We believe that this is the first application of a parasite protease in enzymatic peptide synthesis

    Revisiting previously searched locations in visual neglect: role of right parietal and frontal lesions in misjudging old locations as new

    Get PDF
    Right-hemisphere patients with left neglect often demonstrate abnormal visual search, re-examining stimuli to the right while ignoring those to the left. But re-fixations alone do not reveal if patients misjudge whether they have searched a location before. Here, we not only tracked the eye movements of 16 neglect patients during search, but also asked them to click a response button only when they judged they were fixating a target for the very first time. "Re-clicking" on previously found targets would indicate that patients erroneously respond to these as new discoveries. Lesions were mapped with high-resolution MRI. Neglect patients with damage involving the right intraparietal sulcus or right inferior frontal lobe "re-clicked" on previously found targets on the right at a pathological rate, whereas those with medial occipito-temporal lesions did not. For the intraparietal sulcus patients, the probability of erroneous re-clicks on an old target increased with time since first discovering it; whereas for frontal patients it was independent of search time, suggesting different underlying mechanisms in these two types of patient. Re-click deficits correlated with degree of leftward neglect, mainly due to both being severe in intraparietal cases. These results demonstrate that misjudging previously searched locations for new ones can contribute to pathological search in neglect, with potentially different mechanisms being involved in intraparietal versus inferior frontal patients. When combined with a spatial bias to the right, such deficits might explain why many neglect patients often re-examine rightward locations, at the expense of items to their left

    Rail Infrastructure Manager Problem: Analyzing Capacity Pricing and Allocation in Shared Railway System

    Get PDF
    This paper proposes a train timetabling model for shared railway systems. The model is formulated as a mixed integer linear programming problem and solved both using commercial software and a novel algorithm based on approximate dynamic programming. The results of the train timetabling model can be used to simulate and evaluate the behavior of the infrastructure manager in shared railway systems under different capacity pricing and allocation mechanisms. This would allow regulators and decision makers to identify the implications of these mechanisms for different stakeholders considering the specific characteristics of the system

    A GPU-based survey for millisecond radio transients using ARTEMIS

    Get PDF
    Astrophysical radio transients are excellent probes of extreme physical processes originating from compact sources within our Galaxy and beyond. Radio frequency signals emitted from these objects provide a means to study the intervening medium through which they travel. Next generation radio telescopes are designed to explore the vast unexplored parameter space of high time resolution astronomy, but require High Performance Computing (HPC) solutions to process the enormous volumes of data that are produced by these telescopes. We have developed a combined software /hardware solution (code named ARTEMIS) for real-time searches for millisecond radio transients, which uses GPU technology to remove interstellar dispersion and detect millisecond radio bursts from astronomical sources in real-time. Here we present an introduction to ARTEMIS. We give a brief overview of the software pipeline, then focus specifically on the intricacies of performing incoherent de-dispersion. We present results from two brute-force algorithms. The first is a GPU based algorithm, designed to exploit the L1 cache of the NVIDIA Fermi GPU. Our second algorithm is CPU based and exploits the new AVX units in Intel Sandy Bridge CPUs.Comment: 4 pages, 7 figures. To appear in the proceedings of ADASS XXI, ed. P.Ballester and D.Egret, ASP Conf. Se

    Analysis of Capacity Pricing and Allocation Mechanisms in Shared Railway Systems: Lessons for the Northeast Corridor

    Get PDF
    Recently, governments have started promoting the use of shared railway systems as a way to take advantage of the existing capital-intensive railway infrastructure. Until 1988, all major railways both managed the infrastructure and operated the trains. In contrast, in shared railway systems, multiple train operators utilize the same infrastructure. Such systems can achieve high utilization, but also require coordination between the infrastructure manager and the train operators. Such coordination, in turn, requires capacity planning and regulation that determines which trains can access the infrastructure at each time, capacity allocation, and the access price they need to pay, capacity pricing. The need to establish capacity pricing and allocation mechanisms in the railway system is relatively new and the comparative performance of alternative mechanisms to price and allocate capacity is still a matter of study. This paper proposes a framework to analyze the performance of shared railway systems under alternative capacity pricing and allocation mechanisms. The paper focuses on how the introduction of price-based and capacity-based mechanisms affect the train operators’ ability to access the infrastructure capacity in the context of the Northeast Corridor in the US. The results of this paper suggest that there are trade-offs associated with each mechanism and none of them is superior to the other on all dimensions. As a result, Northeast Corridor stakeholders should carefully analyze the implications of alternative pricing and allocation mechanisms before locking the system into one of them

    Analysis of Climate Policy Targets under Uncertainty

    Get PDF
    Abstract and PDF report are also available on the MIT Joint Program on the Science and Policy of Global Change website (http://globalchange.mit.edu/).Although policymaking in response to the climate change is essentially a challenge of risk management, most studies of the relation of emissions targets to desired climate outcomes are either deterministic or subject to a limited representation of the underlying uncertainties. Monte Carlo simulation, applied to the MIT Integrated Global System Model (an integrated economic and earth system model of intermediate complexity), is used to analyze the uncertain outcomes that flow from a set of century-scale emissions targets developed originally for a study by the U.S. Climate Change Science Program. Results are shown for atmospheric concentrations, radiative forcing, sea ice cover and temperature change, along with estimates of the odds of achieving particular target levels, and for the global costs of the associated mitigation policy. Comparison with other studies of climate targets are presented as evidence of the value, in understanding the climate challenge, of more complete analysis of uncertainties in human emissions and climate system response.This study received support from the MIT Joint Program on the Science and Policy of Global Change, which is funded by a consortium of government, industry and foundation sponsors

    Introduction : screen Londons

    Get PDF
    Our aim, in editing the ‘London Issue’ of this journal, is to contribute to a conversation between scholars of British cinema and television, London historians and scholars of the cinematic city. In 2007, introducing the themed issue on ‘Space and Place in British Cinema and Television’, Steve Chibnall and Julian Petley observed that it would have been possible to fill the whole journal with essays about the representation of London. This issue does just that, responding to the increased interest in cinematic and, to a lesser extent, televisual, Londons, while also demonstrating the continuing fertility of the paradigms of ‘space and place’ for scholars of the moving image1. It includes a wide range of approaches to the topic of London on screen, with varying attention to British institutions of the moving image – such as Channel Four or the British Board of Film Classification – as well as to concepts such as genre, narration and memory. As a whole, the issue, through its juxtapositions of method and approach, shows something of the complexity of encounters between the terms ‘London’, ‘cinema’ and ‘television’ within British film and television studies

    Attitudes towards the use and acceptance of eHealth technologies : a case study of older adults living with chronic pain and implications for rural healthcare

    Get PDF
    Acknowledgements The research described here is supported by the award made by the RCUK Digital Economy programme to the dot.rural Digital Economy Hub; award reference: EP/G066051/1. MC’s time writing the paper is funded by the Scottish Government’s Rural and Environmental Science and Analytical Services Division (RESAS) under Theme 8 ‘Vibrant Rural Communities’ of the Food, Land and People Programme (2011–2016). MC is also an Honorary Research Fellow at the Division of Applied Health Sciences, University of Aberdeen. The input of other members of the TOPS research team, Alastair Mort, Fiona Williams, Sophie Corbett, Phil Wilson and Paul MacNamee who contributed to be wider study and discussed preliminary findings reported here with the authors of the paper is acknowledged. We acknowledge the feedback on earlier versions of this paper provided by members of the Trans-Atlantic Rural Research Network, especially Stefanie Doebler and Carmen Hubbard. We also thank Deb Roberts for her comments.Peer reviewedPublisher PD
    corecore