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  • SPACECRAFT PROPULSION AND POWER  (5)
  • RESEARCH AND SUPPORT FACILITIES (AIR)  (4)
  • Animals  (3)
  • 1
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    Tyrosine phosphorylation of transmembrane ligands for Eph receptors (1997)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1997-03-14
    Description: Axonal pathfinding in the nervous system is mediated in part by cell-to-cell signaling events involving members of the Eph receptor tyrosine kinase (RTK) family and their membrane-bound ligands. Genetic evidence suggests that transmembrane ligands may transduce signals in the developing embryo. The cytoplasmic domain of the transmembrane ligand Lerk2 became phosphorylated on tyrosine residues after contact with the Nuk/Cek5 receptor ectodomain, which suggests that Lerk2 has receptorlike intrinsic signaling potential. Moreover, Lerk2 is an in vivo substrate for the platelet-derived growth factor receptor, which suggests crosstalk between Lerk2 signaling and signaling cascades activated by tyrosine kinases. It is proposed that transmembrane ligands of Eph receptors act not only as conventional RTK ligands but also as receptorlike signaling molecules.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bruckner, K -- Pasquale, E B -- Klein, R -- EY10576/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 1997 Mar 14;275(5306):1640-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany. USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/9054357" target="_blank"〉PubMed〈/a〉
    Keywords: 3T3 Cells ; Animals ; Axons/physiology ; Brain-Derived Neurotrophic Factor/metabolism ; Cell Membrane/*metabolism ; Embryo, Mammalian/metabolism ; Ephrin-B1 ; Ligands ; Mice ; Phosphorylation ; Phosphotyrosine/*metabolism ; Platelet-Derived Growth Factor/pharmacology ; Proteins/*metabolism/pharmacology ; Receptor Protein-Tyrosine Kinases/*metabolism ; Receptor, Ciliary Neurotrophic Factor ; Receptor, EphB2 ; Receptors, Nerve Growth Factor/metabolism ; Receptors, Platelet-Derived Growth Factor/metabolism ; Recombinant Fusion Proteins/metabolism ; Signal Transduction ; Transfection
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    SLC38A9 is a component of the lysosomal amino acid sensing machinery that controls mTORC1 (2015)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2015-01-07
    Description: Cell growth and proliferation are tightly linked to nutrient availability. The mechanistic target of rapamycin complex 1 (mTORC1) integrates the presence of growth factors, energy levels, glucose and amino acids to modulate metabolic status and cellular responses. mTORC1 is activated at the surface of lysosomes by the RAG GTPases and the Ragulator complex through a not fully understood mechanism monitoring amino acid availability in the lysosomal lumen and involving the vacuolar H(+)-ATPase. Here we describe the uncharacterized human member 9 of the solute carrier family 38 (SLC38A9) as a lysosomal membrane-resident protein competent in amino acid transport. Extensive functional proteomic analysis established SLC38A9 as an integral part of the Ragulator-RAG GTPases machinery. Gain of SLC38A9 function rendered cells resistant to amino acid withdrawal, whereas loss of SLC38A9 expression impaired amino-acid-induced mTORC1 activation. Thus SLC38A9 is a physical and functional component of the amino acid sensing machinery that controls the activation of mTOR.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4376665/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4376665/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rebsamen, Manuele -- Pochini, Lorena -- Stasyk, Taras -- de Araujo, Mariana E G -- Galluccio, Michele -- Kandasamy, Richard K -- Snijder, Berend -- Fauster, Astrid -- Rudashevskaya, Elena L -- Bruckner, Manuela -- Scorzoni, Stefania -- Filipek, Przemyslaw A -- Huber, Kilian V M -- Bigenzahn, Johannes W -- Heinz, Leonhard X -- Kraft, Claudine -- Bennett, Keiryn L -- Indiveri, Cesare -- Huber, Lukas A -- Superti-Furga, Giulio -- P 26682/Austrian Science Fund FWF/Austria -- England -- Nature. 2015 Mar 26;519(7544):477-81. doi: 10.1038/nature14107. Epub 2015 Jan 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria. ; Department DiBEST (Biology, Ecology and Earth Sciences), University of Calabria, 87036 Arcavacata di Rende, Italy. ; Biocenter, Division of Cell Biology, Innsbruck Medical University, 6020 Innsbruck, Austria. ; Max F. Perutz Laboratories, University of Vienna, 1030 Vienna, Austria.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25561175" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Transport Systems/*metabolism ; Amino Acids/*metabolism ; Animals ; Cell Line ; Humans ; Lysosomes/*metabolism ; Mice ; Monomeric GTP-Binding Proteins/metabolism ; Multiprotein Complexes/*metabolism ; Nucleotides/metabolism ; TOR Serine-Threonine Kinases/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
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    One-third of reef-building corals face elevated extinction risk from climate change and local impacts (2008)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2008-07-26
    Description: The conservation status of 845 zooxanthellate reef-building coral species was assessed by using International Union for Conservation of Nature Red List Criteria. Of the 704 species that could be assigned conservation status, 32.8% are in categories with elevated risk of extinction. Declines in abundance are associated with bleaching and diseases driven by elevated sea surface temperatures, with extinction risk further exacerbated by local-scale anthropogenic disturbances. The proportion of corals threatened with extinction has increased dramatically in recent decades and exceeds that of most terrestrial groups. The Caribbean has the largest proportion of corals in high extinction risk categories, whereas the Coral Triangle (western Pacific) has the highest proportion of species in all categories of elevated extinction risk. Our results emphasize the widespread plight of coral reefs and the urgent need to enact conservation measures.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Carpenter, Kent E -- Abrar, Muhammad -- Aeby, Greta -- Aronson, Richard B -- Banks, Stuart -- Bruckner, Andrew -- Chiriboga, Angel -- Cortes, Jorge -- Delbeek, J Charles -- Devantier, Lyndon -- Edgar, Graham J -- Edwards, Alasdair J -- Fenner, Douglas -- Guzman, Hector M -- Hoeksema, Bert W -- Hodgson, Gregor -- Johan, Ofri -- Licuanan, Wilfredo Y -- Livingstone, Suzanne R -- Lovell, Edward R -- Moore, Jennifer A -- Obura, David O -- Ochavillo, Domingo -- Polidoro, Beth A -- Precht, William F -- Quibilan, Miledel C -- Reboton, Clarissa -- Richards, Zoe T -- Rogers, Alex D -- Sanciangco, Jonnell -- Sheppard, Anne -- Sheppard, Charles -- Smith, Jennifer -- Stuart, Simon -- Turak, Emre -- Veron, John E N -- Wallace, Carden -- Weil, Ernesto -- Wood, Elizabeth -- New York, N.Y. -- Science. 2008 Jul 25;321(5888):560-3. doi: 10.1126/science.1159196. Epub 2008 Jul 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉IUCN (International Union for Conservation of Nature) Species Programme Species Survival Commission (SSC), Biological Sciences, Old Dominion University, Norfolk, VA 23529, USA. kcarpent@odu.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18653892" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Anthozoa/classification/growth & development ; Caribbean Region ; *Climate ; Conservation of Natural Resources ; *Ecosystem ; *Extinction, Biological ; Greenhouse Effect ; Indian Ocean ; Pacific Ocean ; Risk Assessment ; *Seawater ; Species Specificity ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    Investigation of starting transients in the thermally choked ram accelerator (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An experimental investigation of the starting transients of the thermally choked ram accelerator is presented in this paper. Construction of a highly instrumented tube section and instrumentation inserts provide high resolution experimental pressure, luminosity, and electromagnetic data of the starting transients. Data obtained prior to and following the entrance diaphragm show detailed development of shock systems in both combustible and inert mixtures. With an evacuated launch tube, starting the diffuser is possible at any Mach number above the Kantrowitz Mach number. The detrimental effects and possible solutions of higher launch tube pressures and excessive obturator leakage (blow-by) are discussed. Ignition of a combustible mixture is demonstrated with both perforated and solid obturators. The relative advantages and disadvantages of each are discussed. Data obtained from these starting experiments enhance the understanding of the ram accelerator, as well as assist in the validation of unsteady, chemically reacting CFD codes.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JHU, The 29th JANNAF Combustion Subcommittee Meeting, Volume 1; p 211-234
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  • 5
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    High spatial resolution measurements in a single stage ram accelerator (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: High spatial resolution experimental tube wall pressure measurements of ram accelerator gas dynamic phenomena are presented in this paper. The ram accelerator is a ramjet-in-tube device which operates in a manner similar to that of a conventional ramjet. The projectile resembles the centerbody of a ramjet and travels supersonically through a tube filled with a combustible gaseous mixture, with the tube acting as the outer cowling. Pressure data are recorded as the projectile passes by sensors mounted in the tube wall at various locations along the tube. Utilization of special highly instrumented sections of tube has allowed the recording of gas dynamic phenomena with high resolution. High spatial resolution tube wall pressure data from the three regimes of propulsion studied to date (subdetonative, transdetonative, and superdetonative) in a single stage gas mixture are presented and reveal the three-dimensional character of the flow field induced by projectile fins and the canting of the fins and the canting of the projectile body relative to the tube wall. Also presented for comparison to the experimental data are calculations made with an inviscid, three-dimensional CFD code. The knowledge gained from these experiments and simulations is useful in understanding the underlying nature of ram accelerator propulsive regimes, as well as assisting in the validation of three-dimensional CFD coded which model unsteady, chemically reactive flows.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: JHU, The 29th JANNAF Combustion Subcommittee Meeting, Volume 1; p 189-210
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  • 6
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    Applications of the ram accelerator to hypervelocity aerothermodynamic testing (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A ram accelerator used as a hypervelocity launcher for large-scale aeroballistic range applications in hypersonics and aerodynamics research is presented. It is an in-bore ramjet device in which a projectile shaped like the centerbody of a supersonic ramjet is propelled down a stationary tube filled with a tailored combustible gas mixture. Ram accelerator operation has been demonstrated at 39 mm and 90 mm bores, supporting the proposition that this launcher concept can be scaled up to very large bore diameters of the order of 30-60 cm. It is concluded that high quality data obtained from the tube wall and projectile during the aceleration process itself are very useful for understanding aerothermodynamics of hypersonic flow in general, and for providing important CFD validation benchmarks.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: AIAA PAPER 92-3949
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  • 7
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    The ram accelerator - A chemically driven mass launcher (1988)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The ram accelerator, a chemically propelled mass driver, is presented as a viable new approach for directly launching acceleration-insensitive payloads into low earth orbit. The propulsion principle is similar to that of a conventional air-breathing ramjet. The cargo vehicle resembles the center-body of a ramjet and travels through a tube filled with a pre-mixed fuel and oxidizer mixture. The launch tube acts as the outer cowling of the ramjet and the combustion process travels with the vehicle. Two drive modes of the ram accelerator propulsion system are described, which when used in sequence are capable of accelerating the vehicle to as high as 10 km/sec. The requirements are examined for placing a 2000 kg vehicle into a 500 km orbit with a minimum of on-board rocket propellant for circularization maneuvers. It is shown that aerodynamic heating during atmospheric transit results in very little ablation of the nose. An indirect orbital insertion scenario is selected, utilizing a three step maneuver consisting of two burns and aerobraking. An on-board propulsion system using storable liquid propellants is chosen in order to minimize propellant mass requirements, and the use of a parking orbit below the desired final orbit is suggested as a means to increase the flexibility of the mass launch concept. A vehicle design using composite materials is proposed that will best meet the structural requirements, and a preliminary launch tube design is presented.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: AIAA PAPER 88-2968
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  • 8
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    Experiments on hypersonic ramjet propulsion cycles using a ram accelerator (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Work on hypersonic propulsion research using a ram accelerator is presented. Several different ram accelerator propulsive cycles have been experimentally demonstrated over the Mach number range of 3 to 8.5. The subsonic, thermally choked combustion mode has accelerated projectiles to near the Chapman-Jouguet (C-J) detonation velocity within many different propellant mixtures. In the transdetonative velocity regime (85 to 115 percent of C-J speed), projectiles have established a propulsive cycle which allows them to transition smoothly from subdetonative to superdetonative velocities. Luminosity data indicate that the combustion process moves forward onto the projectile body as it approaches the C-J speed. In the superdetonative velocity range, the projectiles accelerate while always traveling faster than the C-J velocity. Ram accelerator projectiles operating continuously through these velocity regimes generate distinctive hypersonic phenomena which can be studied very effectively in the laboratory. These results would be very useful for validating sophisticated CFD computer codes and in collecting engineering data for potential airbreathing hypersonic propulsive systems.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: AIAA PAPER 91-2489
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  • 9
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    High effectiveness liquid droplet/gas heat exchanger for space power applications (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A high-effectiveness liquid droplet/gas heat exchanger (LDHX) concept for thermal management in space is described. Heat is transferred by direct contact between fine droplets (approximately 100-300 microns in diameter) of a suitable low vapor pressure liquid and an inert working gas. Complete separation of the droplet and gas media in the zero-g environment is accomplished by configuring the LDHX as a vortex chamber.The large heat transfer area presented by the small droplets permits heat exchanger effectiveness of 0.9-0.95 in a compact, lightweight geometry which avoids many of the limitations of conventional plate and fin or tube and shell heat exchangers, such as their tendency toward single point failure. The application of the LDHX in a high temperature Brayton cycle is discussed to illustrate the performance and operational characteristics of this new heat exchanger concept.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: IAF PAPER 83-433
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  • 10
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    Investigation of advanced propulsion technologies: The RAM accelerator and the flowing gas radiation heater (1992)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The two principal areas of advanced propulsion investigated are the ram accelerator and the flowing gas radiation heater. The concept of the ram accelerator is presented as a hypervelocity launcher for large-scale aeroballistic range applications in hypersonics and aerothermodynamics research. The ram accelerator is an in-bore ramjet device in which a projectile shaped like the centerbody of a supersonic ramjet is propelled in a stationary tube filled with a tailored combustible gas mixture. Combustion on and behind the projectile generates thrust which accelerates it to very high velocities. The acceleration can be tailored for the 'soft launch' of instrumented models. The distinctive reacting flow phenomena that have been observed in the ram accelerator are relevant to the aerothermodynamic processes in airbreathing hypersonic propulsion systems and are useful for validating sophisticated CFD codes. The recently demonstrated scalability of the device and the ability to control the rate of acceleration offer unique opportunities for the use of the ram accelerator as a large-scale hypersonic ground test facility. The flowing gas radiation receiver is a novel concept for using solar energy to heat a working fluid for space power or propulsion. Focused solar radiation is absorbed directly in a working gas, rather than by heat transfer through a solid surface. Previous theoretical analysis had demonstrated that radiation trapping reduces energy loss compared to that of blackbody receivers, and enables higher efficiencies and higher peak temperatures. An experiment was carried out to measure the temperature profile of an infrared-active gas and demonstrate the effect of radiation trapping. The success of this effort validates analytical models of heat transfer in this receiver, and confirms the potential of this approach for achieving high efficiency space power and propulsion.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-199376 , NAS 1.26:199376
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