917 research outputs found

    Evaluation of the Malcolm horizon in a moving-base flight simulator

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    The efficacy of the Malcolm Horizon (MH) in a controlled, simulated, instrument flight environment was examined. Eight flight parameters were used to compare performance under experimental and control conditions. The parameters studied were pitch attitude, roll attitude, turn rate, airspeed, vertical velocity, heading, altitude, and course deviation. Testing of a commercial realization of the MH concept in a flight simulator revealed strengths and weaknesses of the currently available MH hardware

    Energy Efficiency Policies: A Retrospective Examination

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    We review literature on several types of energy efficiency policies: appliance standards, financial incentive programs, information and voluntary programs, and management of government energy use. For each, we provide a brief synopsis of the relevant programs, along with available existing estimates of energy savings, costs, and cost-effectiveness at a national level. The literature examining these estimates points to potential issues in determining the energy savings and costs, but recent evidence suggests that techniques for measuring both have improved. Taken together, the literature identifies up to four quads of energy savings annually from these programs - at least half of which is attributable to appliance standards and utility-based demand-side management, with possible additional energy savings from the U.S. Department of Energy's (DOE's) ENERGY STAR, Climate Challenge, and Section 1605b voluntary programs to reduce carbon dioxide (CO 2) emissions. Related reductions in CO 2 and criteria air pollutants may contribute an additional 10% to the value of energy savings above the price of energy itself. Copyright © 2006 by Annual Reviews. All rights reserved

    Long coiled-coil proteins and membrane traffic

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    AbstractProtein transport between organelles is mediated by vesicles which must accurately dock and fuse with appropriate compartments. Over the past several years a large number of long coiled-coil proteins have been identified on the Golgi and on endosomes, mostly as auto-antigens in autoimmune disorders. Based on their restricted intracellular distributions and their predicted rod-like structure, these proteins have been proposed to play a role in tethering vesicles to target organelles prior to fusion. However, such proteins may also play a structural role, for example as components of a Golgi matrix, or as scaffolds for the assembly of other factors important for fusion. This review will examine what is known about the function of these large coiled-coil proteins in membrane traffic

    The golgin coiled-coil proteins capture different types of transport carriers via distinct N-terminal motifs

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    Abstract Background The internal organization of cells depends on mechanisms to ensure that transport carriers, such as vesicles, fuse only with the correct destination organelle. Several types of proteins have been proposed to confer specificity to this process, and we have recently shown that a set of coiled-coil proteins on the Golgi, called golgins, are able to capture specific classes of carriers when relocated to an ectopic location. Results Mapping of six different golgins reveals that, in each case, a short 20–50 residue region is necessary and sufficient to capture specific carriers. In all six of GMAP-210, golgin-84, TMF, golgin-97, golgin-245, and GCC88, this region is located at the extreme N-terminus of the protein. The vesicle-capturing regions of GMAP-210, golgin-84, and TMF capture intra-Golgi vesicles and share some sequence features, suggesting that they act in a related, if distinct, manner. In the case of GMAP-210, this shared feature is in addition to a previously characterized “amphipathic lipid-packing sensor” motif that can capture highly curved membranes, with the two motifs being apparently involved in capturing distinct types of vesicles. Of the three GRIP domain golgins that capture endosome-to-Golgi carriers, golgin-97 and golgin-245 share a closely related capture motif, whereas that in GCC88 is distinct, suggesting that it works by a different mechanism and raising the possibility that the three golgins capture different classes of endosome-derived carriers that share many cargos but have distinct features for recognition at the Golgi. Conclusions For six different golgins, the capture of carriers is mediated by a short region at the N-terminus of the protein. There appear to be at least four different types of motif, consistent with specific golgins capturing specific classes of carrier and implying the existence of distinct receptors present on each of these different carrier classes

    The golgin coiled-coil proteins capture different types of transport carriers via distinct N-terminal motifs.

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    BACKGROUND: The internal organization of cells depends on mechanisms to ensure that transport carriers, such as vesicles, fuse only with the correct destination organelle. Several types of proteins have been proposed to confer specificity to this process, and we have recently shown that a set of coiled-coil proteins on the Golgi, called golgins, are able to capture specific classes of carriers when relocated to an ectopic location. RESULTS: Mapping of six different golgins reveals that, in each case, a short 20-50 residue region is necessary and sufficient to capture specific carriers. In all six of GMAP-210, golgin-84, TMF, golgin-97, golgin-245, and GCC88, this region is located at the extreme N-terminus of the protein. The vesicle-capturing regions of GMAP-210, golgin-84, and TMF capture intra-Golgi vesicles and share some sequence features, suggesting that they act in a related, if distinct, manner. In the case of GMAP-210, this shared feature is in addition to a previously characterized "amphipathic lipid-packing sensor" motif that can capture highly curved membranes, with the two motifs being apparently involved in capturing distinct types of vesicles. Of the three GRIP domain golgins that capture endosome-to-Golgi carriers, golgin-97 and golgin-245 share a closely related capture motif, whereas that in GCC88 is distinct, suggesting that it works by a different mechanism and raising the possibility that the three golgins capture different classes of endosome-derived carriers that share many cargos but have distinct features for recognition at the Golgi. CONCLUSIONS: For six different golgins, the capture of carriers is mediated by a short region at the N-terminus of the protein. There appear to be at least four different types of motif, consistent with specific golgins capturing specific classes of carrier and implying the existence of distinct receptors present on each of these different carrier classes

    Golgi coiled-coil proteins contain multiple binding sites for Rab family G proteins

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    Vesicles and other carriers destined for the Golgi apparatus must be guided to the correct cisternae. Golgins, long coiled-coil proteins that localize to particular Golgi subdomains via their C termini, are candidate regulators of vesicle sorting. In this study, we report that the GRIP domain golgins, whose C termini bind the Arf-like 1 G protein on the trans-Golgi, can also bind four members of the Rab family of G proteins. The Rab2-, Rab6-, Rab19-, and Rab30-binding sites are within the coiled-coil regions that are not required for Golgi targeting. Binding sites for two of these Rabs are also present on two coiled-coil proteins of the cis-Golgi, the Drosophila melanogaster orthologues of GM130 and GMAP-210. We suggest an integrated model for a tentacular Golgi in which coiled-coil proteins surround the Golgi to capture and retain Rab-containing membranes, excluding other structures such as ribosomes. Binding sites for diverse Rabs could ensure that incoming carriers are captured on first contact and moved to their correct destination within the stack

    Modeling Uncertainty in Climate Change: A Multi-Model Comparison

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    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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