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Sample records for leo npinen lo

  1. Leo

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    (the Lion; abbrev. Leo, gen. Leonis; area 947 sq. deg.) A northern zodiacal constellation which lies between Cancer and Virgo, and culminates at midnight in early March. It represents the Nemean lion that, in Greek mythology, Hercules killed as the first of his 12 labors. Its brightest stars were cataloged by Ptolemy (c. AD 100-175) in the Almagest....

  2. Leo Minor

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    (the Lesser Lion; abbrev. LMi, gen. Leonis Minoris; area 232 sq.deg.) A northern constellation which lies between Ursa Major and Leo, and culminates at midnight in late February. It was introduced by the astronomer Johannes Hevelius (1611-87) of Danzig (Gdansk), who included it in his atlas Firmamentum Sobiescianum sive Uranographia of 1687....

  3. Leo Doyle, master surgeon.

    PubMed

    Vellar, I

    2000-10-01

    On 3 March 1953 Leo Doyle died at the Mercy Hospital, Melbourne. The day before he died Leo Doyle had been operating at the Mercy Hospital when he took ill. Doyle's final illness was almost certainly the result of the severe aortic stenosis that had been developing over some years. His death at the relatively young age of 61 ended the career of a man described by Sir Gordon Gordon Taylor as the greatest technical surgeon that he had ever seen. In all likelihood Australian surgery will never see the likes of Doyle, a virtuoso surgeon, again. And yet to many of the surgeons who were Doyle's contemporaries and to those who followed him he remained somewhat of an enigma. Perhaps in some way the description of the great French surgeon Baron Dupuytren may also be applicable to Leo Doyle: known to all, loved by many, understood by few. By all accounts Leo Doyle's surgical repertoire knew no bounds. He operated with equal facility on the central nervous system, the head and neck, in the thorax, abdomen and pelvis and he was more than competent in gynaecology, urology and orthopaedics. In the latter part of his career he became, par excellence, a cancer surgeon. He was, arguably, Australia's first surgical oncologist. No procedure was deemed too complicated or demanding. Like some other superb technicians his judgement at times did not match his technical ability. Doyle was one of the first surgeons in Australia to perform hindquarter amputation and he helped to pioneer the operations of total gastrectomy and oesophagogastrectomy. An avid reader of the surgical literature, he possessed an enormous library which was matched by an equally large collection of surgical instruments. Unlike Devine he published relatively little. He was not a good clinical teacher, preferring to teach by example in the operating theatre. Although interested in music and the visual arts, surgery was his life.

  4. Lunar Exploration Orbiter (LEO)

    NASA Astrophysics Data System (ADS)

    Jaumann, R.; Spohn, T.; Hiesinger, H.; Jessberger, E. K.; Neukum, G.; Oberst, J.; Helbert, J.; Christensen, U.; Keller, H. U.; Mall, U.; Böhnhardt, H.; Hartogh, P.; Glassmeier, K.-H.; Auster, H.-U.; Moreira, A.; Werner, M.; Pätzold, M.; Palme, H.; Wimmer-Schweingruber, R.; Mandea, M.; Lesur, V.; Häusler, B.; Hördt, A.; Eichentopf, K.; Hauber, E.; Hoffmann, H.; Köhler, U.; Kührt, E.; Michaelis, H.; Pauer, M.; Sohl, F.; Denk, T.; van Gasselt, S.

    2007-08-01

    The Moon is an integral part of the Earth-Moon system, it is a witness to more than 4.5 b. y. of solar system history, and it is the only planetary body except Earth for which we have samples from known locations. The Moon is our closest companion and can easily be reached from Earth at any time, even with a relatively modest financial budget. Consequently, the Moon was the first logical step in the exploration of our solar system before we pursued more distant targets such as Mars and beyond. The vast amount of knowledge gained from the Apollo and other lunar missions of the late 1960's and early 1970's demonstrates how valuable the Moon is for the understanding of our planetary system. Even today, the Moon remains an extremely interesting target scientifically and technologically, as ever since, new data have helped to address some of our questions about the Earth-Moon system, many questions remained. Therefore, returning to the Moon is the critical stepping-stone to further exploring our immediate planetary neighborhood. In this concept study, we present scientific and technological arguments for a national German lunar mission, the Lunar Explorations Orbiter (LEO). Numerous space-faring nations have realized and identified the unique opportunities related to lunar exploration and have planned missions to the Moon within the next few years. Among these missions, LEO will be unique, because it will globally explore the Moon in unprecedented spatial and spectral resolution. LEO will significantly improve our understanding of the lunar surface composition, surface ages, mineralogy, physical properties, interior, thermal history, gravity field, regolith structure, and magnetic field. The Lunar Explorations Orbiter will carry an entire suite of innovative, complementary technologies, including high-resolution camera systems, several spectrometers that cover previously unexplored parts of the electromagnetic spectrum over a broad range of wavelengths, microwave and

  5. Mitochondrial genome of the African lion Panthera leo leo.

    PubMed

    Ma, Yue-ping; Wang, Shuo

    2015-01-01

    In this study, the complete mitochondrial genome sequence of the African lion P. leo leo was reported. The total length of the mitogenome was 17,054 bp. It contained the typical mitochondrial structure, including 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes and 1 control region; 21 of the tRNA genes folded into typical cloverleaf secondary structure except for tRNASe. The overall composition of the mitogenome was A (32.0%), G (14.5%), C (26.5%) and T (27.0%). The new sequence will provide molecular genetic information for conservation genetics study of this important large carnivore.

  6. GFEChutes Lo-Fi

    NASA Technical Reports Server (NTRS)

    Gist, Emily; Turner, Gary; Shelton, Robert; Vautier, Mana; Shaikh, Ashraf

    2013-01-01

    NASA needed to provide a software model of a parachute system for a manned re-entry vehicle. NASA has parachute codes, e.g., the Descent Simulation System (DSS), that date back to the Apollo Program. Since the space shuttle did not rely on parachutes as its primary descent control mechanism, DSS has not been maintained or incorporated into modern simulation architectures such as Osiris and Antares, which are used for new mission simulations. GFEChutes Lo-Fi is an object-oriented implementation of conventional parachute codes designed for use in modern simulation environments. The GFE (Government Furnished Equipment), low-fidelity (Lo-Fi) parachute model (GFEChutes Lo-Fi) is a software package capable of modeling the effects of multiple parachutes, deployed concurrently and/or sequentially, on a vehicle during the subsonic phase of reentry into planetary atmosphere. The term "low-fidelity" distinguishes models that represent the parachutes as simple forces acting on the vehicle, as opposed to independent aerodynamic bodies. GFEChutes Lo-Fi was created from these existing models to be clean, modular, certified as NASA Class C software, and portable, or "plug and play." The GFE Lo-Fi Chutes Model provides basic modeling capability of a sequential series of parachute activities. Actions include deploying the parachute, changing the reefing on the parachute, and cutting away the parachute. Multiple chutes can be deployed at any given time, but all chutes in that case are assumed to behave as individually isolated chutes; there is no modeling of any interactions between deployed chutes. Drag characteristics of a deployed chute are based on a coefficient of drag, the face area of the chute, and the local dynamic pressure only. The orientation of the chute is approximately modeled for purposes of obtaining torques on the vehicle, but the dynamic state of the chute as a separate entity is not integrated - the treatment is simply an approximation. The innovation in GFEChutes

  7. Leo Tolstoy the Spiritual Educator

    ERIC Educational Resources Information Center

    Moulin, Dan

    2008-01-01

    This paper considers the often overlooked religious and educational works of the Russian novelist Leo Tolstoy (1828-1910). After outlining Tolstoy's life, religious and educational views, it is argued that Tolstoy has much to offer spiritual educators today. In particular, it suggests Tolstoy's insistence on the absolute and eternal nature of…

  8. Wave optics-based LEO-LEO radio occultation retrieval

    NASA Astrophysics Data System (ADS)

    Benzon, Hans-Henrik; Høeg, Per

    2016-06-01

    This paper describes the theory for performing retrieval of radio occultations that use probing frequencies in the XK and KM band. Normally, radio occultations use frequencies in the L band, and GPS satellites are used as the transmitting source, and the occultation signals are received by a GPS receiver on board a Low Earth Orbit (LEO) satellite. The technique is based on the Doppler shift imposed, by the atmosphere, on the signal emitted from the GPS satellite. Two LEO satellites are assumed in the occultations discussed in this paper, and the retrieval is also dependent on the decrease in the signal amplitude caused by atmospheric absorption. The radio wave transmitter is placed on one of these satellites, while the receiver is placed on the other LEO satellite. One of the drawbacks of normal GPS-based radio occultations is that external information is needed to calculate some of the atmospheric products such as the correct water vapor content in the atmosphere. These limitations can be overcome when a proper selected range of high-frequency waves are used to probe the atmosphere. Probing frequencies close to the absorption line of water vapor have been included, thus allowing the retrieval of the water vapor content. Selecting the correct probing frequencies would make it possible to retrieve other information such as the content of ozone. The retrieval is performed through a number of processing steps which are based on the Full Spectrum Inversion (FSI) technique. The retrieval chain is therefore a wave optics-based retrieval chain, and it is therefore possible to process measurements that include multipath. In this paper simulated LEO to LEO radio occultations based on five different frequencies are used. The five frequencies are placed in the XK or KM frequency band. This new wave optics-based retrieval chain is used on a number of examples, and the retrieved atmospheric parameters are compared to the parameters from a global European Centre for Medium

  9. New NASA SEE LEO Spacecraft Charging Design Guidelines: How to Survive in LEO Rather Than GEO

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.; Hillard, G. Barry

    2003-01-01

    It has been almost two solar cycles since the 1984 GEO Guidelines of Purvis, Garrett, Whittlesey, and Stevens were published. In that time, interest in high voltage LEO systems has increased. Correct and conventional wisdom has been that LEO conditions are sufficiently different from GEO that the GEO Guidelines (and other GEO and POLAR documents produced since then) should not be used for LEO spacecraft. Because of significant recent GEO spacecraft failures that have been shown in ground testing to be likely to also occur on LEO spacecraft, the SEE program commissioned the production of the new LEO Spacecraft Charging Design Guidelines. Now available in CD-ROM form, the LEO Guidelines highlight mitigation techniques to prevent spacecraft arcing on LEO solar arrays and other systems. We compare and contrast the mitigation techniques for LEO and GEO in this paper. We also discuss the extensive bibliography included in the LEO Guidelines, so results can be found in their primary sources.

  10. New NASA SEE LEO Spacecraft Charging Design Guidelines: How to Survive in LEO Rather than GEO

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.; Hillard, G. Barry

    2004-01-01

    It has been almost two solar cycles since the GEO Guidelines of Purvis et al (1984) were published. In that time, interest in high voltage LEO systems has increased. The correct and conventional wisdom has been that LEO conditions are sufficiently different from GEO that the GEO Guidelines (and other GEO and POLAR documents produced since then) should not be used for LEO spacecraft. Because of significant recent GEO spacecraft failures that have been shown in ground testing to be likely to also occur on LEO spacecraft, the SEE program commissioned the production of the new LEO Spacecraft Charging Design Guidelines (hereafter referred to as the LEO Guidelines). Now available in CD-ROM form, the LEO Guidelines highlight mitigation techniques to prevent spacecraft arcing on LEO solar arrays and other systems. We compare and contrast the mitigation techniques for LEO and GEO in this paper. We also discuss the extensive bibliography included in the LEO Guidelines, so results can be found in their primary sources.

  11. XML Format for SESAME and LEOS

    SciTech Connect

    Durrenberger, J K; Neely, J R; Sterne, P A

    2009-04-29

    The objective of this document is to describe the XML format used by LLNL and LANL to represent the equation-of-state and related material information in the LEOS and SESAME data libraries. The primary purpose of this document is to describe a specific XML format for representing EOS data that is tailored to the nature of the underlying data and is amenable to conversion to both legacy SESAME and LEOS binary formats. The secondary purpose is to describe an XML format that lends itself to a 'natural' representation in a binary file format of the SESAME, pdb or hdf5 form so that this format and related tools can be used for the rapid and efficient development and implementation of prototype data structures. This document describes the XML format only. A working knowledge of LEOS and SESAME formats is assumed.

  12. NASA STD-4005: The LEO Spacecraft Charging Design Standard

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.

    2006-01-01

    Power systems with voltages higher than about 55 volts may charge in Low Earth Orbit (LEO) enough to cause destructive arcing. The NASA STD-4005 LEO Spacecraft Charging Design Standard will help spacecraft designers prevent arcing and other deleterious effects on LEO spacecraft. The Appendices, an Information Handbook based on the popular LEO Spacecraft Charging Design Guidelines by Ferguson and Hillard, serve as a useful explanation and accompaniment to the Standard.

  13. The Philosophical Politics of Leo Strauss.

    ERIC Educational Resources Information Center

    Auerbach, Maurice

    1985-01-01

    Leo Strauss' views concerning the way to teach political philosophy are discussed. The essay begins with a summary of Strauss' general conception of classical political philosophy. The remainder of the essay discusses the content of Strauss' book "What is Political Philosophy?" (RM)

  14. Leo Strauss: Education and the Body Politic

    ERIC Educational Resources Information Center

    Fennell, Jon M.; Simpson, Timothy L.

    2008-01-01

    Leo Strauss is commonly cited as a seminal influence for the neoconservatism that, in the minds of many commentators, dominates the administration of George W. Bush. What intersection, if any, exists between Strauss's views and neoconservatism? This paper investigates that question by studying Strauss's writings on liberal education and assessing…

  15. Raising a Child in the Punana Leo

    ERIC Educational Resources Information Center

    Iokepa-Guerrero, Noelani

    2008-01-01

    At the Punana Leo everyone, "'Anakala", uncle--a male teacher, "'Anake," aunty--a female teacher, and the "keiki," children all play important roles in the educational program of the school. Each and all are responsible for the learning that takes place and the success of the program. In this article, the author…

  16. In Memory of Leo P. Kadanoff

    NASA Astrophysics Data System (ADS)

    Wegner, Franz J.

    2016-10-01

    Leo Kadanoff has worked in many fields of statistical mechanics. His contributions had an enormous impact. This holds in particular for critical phenomena, where he explained Widom's homogeneity laws by means of block-spin transformations and laid the basis for Wilson's renormalization group equation. I had the pleasure to work in his group for 1 year. A short historical account is given.

  17. Low-Cost Propellant Launch to LEO from a Tethered Balloon - 'Propulsion Depots' Not 'Propellant Depots'

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian H.; Schneider, Evan G.; Vaughan, David A.; Hall, Jeffrey L.; Yu, Chi Yau

    2011-01-01

    As we have previously reported, it may be possible to launch payloads into low-Earth orbit (LEO) at a per-kilogram cost that is one to two orders of magnitude lower than current launch systems, using only a relatively small capital investment (comparable to a single large present-day launch). An attractive payload would be large quantities of high-performance chemical rocket propellant (e.g. Liquid Oxygen/Liquid Hydrogen (LO2/LH2)) that would greatly facilitate, if not enable, extensive exploration of the moon, Mars, and beyond.

  18. What Happened to Leo P's Metals?

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-12-01

    Measurements of metal abundances in galaxies present a conundrum: compared to expectations, there are not nearly enough metals observed within galaxies. New observations of a nearby dwarf galaxy may help us understand where this enriched material went.Removal ProcessesStar formation is responsible for the build-up of metals (elements heavier than helium) in a galaxy. But when we use a galaxys star-formation history to estimate the amount of enriched material it should contain, our predictions are inconsistent with measured abundances: large galaxies contain only about 2025% of the expected metals, and small dwarf galaxies contain as little as 1%!So what happens to galaxies metals after they have been formed? The favored explanation is that metals are removed from galaxies via stellar feedback: stars that explode in violent supernovae can drive high-speed winds, expelling the enriched material from a galaxy. This process should be more efficient in low-mass galaxies due to their smaller gravitational wells, which would explain why low-mass galaxies have especially low metallicities.But external processes may also contribute to the removal of metals, such as tidal stripping during interactions between galaxies. To determine the role of stellar feedback alone, an ideal test would be to observe an isolated low-mass, star-forming galaxy i.e., one that is not affected by external processes.Luckily, such an isolated, low-mass galaxy has recently been discovered just outside of the Local Group: Leo P, a gas-rich dwarf galaxy with a total stellar mass of 5.6 x 105 solar masses.Isolated ResultsPercentage of oxygen lost in Leo P compared to the percentage of metals lost in three other, similar-size dwarfs that are not isolated. If the gas-phase oxygen in Leo P were removed, Leo Ps measurements would be consistent with those of the other dwarfs. [McQuinn et al. 2015]Led by Kristen McQuinn (University of Minnesota, University of Texas at Austin), a team of researchers has used

  19. Leo Kadanoff's legacy for turbulent thermal convection

    NASA Astrophysics Data System (ADS)

    Lohse, Detlef

    Rayleigh-Benard (RB) convection -- the buoyancy-driven flow of a fluid heated from below and cooled from above -- is a classical problem in fluid dynamics. It played a crucial role in the development of stability theory in hydrodynamics (Rayleigh, Chandrasekhar) and had been paradigmatic in pattern formation and in the study of spatial-temporal chaos (Ahlers, Libchaber, and many other). It was Leo Kadanoff and his associates in Chicago who, in the 1980s and 1990s, propagated the RB system as paradigmatic for the physics of fully developed turbulence and contributed tremendously to today's understanding of thermally driven turbulence. He and his experimental coworkers (Libchaber et al.) revealed the importance of the thermal plumes and the large-scale wind, and elucidated the interplay between thermal boundary layers and bulk. His scaling analysis laid the basis for our present understanding of turbulent convection, which I will review in this talk, highlighting Leo's trailblazing contributions. Kadanoff session.

  20. Nickel metal hydride LEO cycle testing

    NASA Technical Reports Server (NTRS)

    Lowery, Eric

    1995-01-01

    The George C. Marshall Space Flight Center is working to characterize aerospace AB5 Nickel Metal Hydride (NiMH) cells. The cells are being evaluated in terms of storage, low earth orbit (LEO) cycling, and response to parametric testing (high rate charge and discharge, charge retention, pulse current ability, etc.). Cells manufactured by Eagle Picher are the subjects of the evaluation. There is speculation that NiMH cells may become direct replacements for current Nickel Cadmium cells in the near future.

  1. Hugoniot Models for Na and LiF from LEOS

    SciTech Connect

    Whitley, Heather D.; Wu, Christine J.

    2016-10-12

    In this document, we provide the Hugoniot for sodium from two models: LEOS table L110 and Lynx table 110. We also provide the Hugoniot for lithium fluoride from LEOS (L2240) and Lynx (2240). The Hugoniot pressures are supplied for temperatures between 338.0 and 1.16×109 Kelvin and densities between 0.968 and 11.5 g/cc. These LEOS models were developed by the quotidian EOS methodology, which is a widely used and robust method for producing tabular EOS data. Tables list the model data for LEOS 110, Lynx 110, LEOS 2240, and Lynx 2240. The Lynx models follow the same methodology as the LEOS models; however, the Purgatorio average-atom DFT code was used to compute the electron thermal part of the EOS. The models for Lynx are only listed at high compression due to known issues with the Lynx library at lower pressures.

  2. Leo Satellite Communication through a LEO Constellation using TCP/IP Over ATM

    NASA Technical Reports Server (NTRS)

    Foore, Lawrence R.; Konangi, Vijay K.; Wallett, Thomas M.

    1999-01-01

    The simulated performance characteristics for communication between a terrestrial client and a Low Earth Orbit (LEO) satellite server are presented. The client and server nodes consist of a Transmission Control Protocol /Internet Protocol (TCP/IP) over ATM configuration. The ATM cells from the client or the server are transmitted to a gateway, packaged with some header information and transferred to a commercial LEO satellite constellation. These cells are then routed through the constellation to a gateway on the globe that allows the client/server communication to take place. Unspecified Bit Rate (UBR) is specified as the quality of service (QoS). Various data rates are considered.

  3. The IBEX-Lo Sensor

    NASA Astrophysics Data System (ADS)

    Fuselier, S. A.; Bochsler, P.; Chornay, D.; Clark, G.; Crew, G. B.; Dunn, G.; Ellis, S.; Friedmann, T.; Funsten, H. O.; Ghielmetti, A. G.; Googins, J.; Granoff, M. S.; Hamilton, J. W.; Hanley, J.; Heirtzler, D.; Hertzberg, E.; Isaac, D.; King, B.; Knauss, U.; Kucharek, H.; Kudirka, F.; Livi, S.; Lobell, J.; Longworth, S.; Mashburn, K.; McComas, D. J.; Möbius, E.; Moore, A. S.; Moore, T. E.; Nemanich, R. J.; Nolin, J.; O'Neal, M.; Piazza, D.; Peterson, L.; Pope, S. E.; Rosmarynowski, P.; Saul, L. A.; Scherrer, J. R.; Scheer, J. A.; Schlemm, C.; Schwadron, N. A.; Tillier, C.; Turco, S.; Tyler, J.; Vosbury, M.; Wieser, M.; Wurz, P.; Zaffke, S.

    2009-08-01

    The IBEX-Lo sensor covers the low-energy heliospheric neutral atom spectrum from 0.01 to 2 keV. It shares significant energy overlap and an overall design philosophy with the IBEX-Hi sensor. Both sensors are large geometric factor, single pixel cameras that maximize the relatively weak heliospheric neutral signal while effectively eliminating ion, electron, and UV background sources. The IBEX-Lo sensor is divided into four major subsystems. The entrance subsystem includes an annular collimator that collimates neutrals to approximately 7°×7° in three 90° sectors and approximately 3.5°×3.5° in the fourth 90° sector (called the high angular resolution sector). A fraction of the interstellar neutrals and heliospheric neutrals that pass through the collimator are converted to negative ions in the ENA to ion conversion subsystem. The neutrals are converted on a high yield, inert, diamond-like carbon conversion surface. Negative ions from the conversion surface are accelerated into an electrostatic analyzer (ESA), which sets the energy passband for the sensor. Finally, negative ions exit the ESA, are post-accelerated to 16 kV, and then are analyzed in a time-of-flight (TOF) mass spectrometer. This triple-coincidence, TOF subsystem effectively rejects random background while maintaining high detection efficiency for negative ions. Mass analysis distinguishes heliospheric hydrogen from interstellar helium and oxygen. In normal sensor operations, eight energy steps are sampled on a 2-spin per energy step cadence so that the full energy range is covered in 16 spacecraft spins. Each year in the spring and fall, the sensor is operated in a special interstellar oxygen and helium mode during part of the spacecraft spin. In the spring, this mode includes electrostatic shutoff of the low resolution (7°×7°) quadrants of the collimator so that the interstellar neutrals are detected with 3.5°×3.5° angular resolution. These high angular resolution data are combined with

  4. Impact of LEO satellites on global GPS solutions

    NASA Astrophysics Data System (ADS)

    Rothacher, M.; Svehla, D.

    2003-04-01

    Already at present quite a few Low Earth Orbiting (LEO) satellites (SAC-C, CHAMP, JASON-1, GRACE-1 and GRACE-2) are equipped with one or more GPS receivers for precise orbit determination or other applications (atmospheric sounding, gravity field recovery, ...). This trend will continue in the near future (e.g., with the GOCE and COSMIC missions) and we will soon have an entire``constellation´´ of LEO satellites tracked by GPS at our disposal. In this contribution we study the impact of LEO GPS measurements (from a single LEO satellite or from a LEO constellation) on global GPS solutions, where GPS satellite orbits and clocks, Earth rotation parameters (ERPs), station coordinates and troposphere zenith delays are determined simultaneously. In order to assess the impact of the LEO GPS data on global IGS results, we perform a combined analysis of the space-borne and the ground-based GPS data. Such a combination may benefit on one hand from the differences between a ground station and a LEO, namely, (1) the different tracking geometry (coverage of isolated geographical areas by LEOs, rapidly changing geometry, ...); (2) that LEOs connect all ground stations within 1-2 hours; (3) that baselines between LEO and ground stations may be longer than station-station baselines; (4) that no tropospheric delays have to be estimated for LEOs; and (5) that LEOs orbit the Earth within the ionosphere and may therefore contribute to global ionosphere models. On the other hand we have to deal with difficult aspects of precise orbit determination for the LEOs: only if we succeed to obtain very accurate dynamic or reduced-dynamic orbits for the LEOs, we will have a chance to improve the global GPS results at all. We present first results concerning the influence of LEO data on GPS orbits, ERPs, site coordinates, and troposphere zenith delays using both, variance-covariance analyses based on simulated data and combined global solutions based on real CHAMP and JASON data and the data

  5. Instability of the Present LEO Satellite Populations

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi; Johnson, Nicholas L.

    2006-01-01

    Several studies conducted during 1991-2001 demonstrated, with some assumed launch rates, the future unintended growth potential of the Earth satellite population, resulting from random, accidental collisions among resident space objects. In some low Earth orbit (LEO) altitude regimes where the number density of satellites is above a critical spatial density, the production rate of new breakup debris due to collisions would exceed the loss of objects due to orbital decay. A new study has been conducted in the Orbital Debris Program Office at the NASA Lyndon B. Johnson Space Center, using higher fidelity models to evaluate the current debris environment. The study assumed no satellites were launched after December 2005. A total of 150 Monte Carlo runs were carried out and analyzed. Each Monte Carlo run simulated the current debris environment and projected it 200 years into the future. The results indicate that the LEO debris environment has reached a point such that even if no further space launches were conducted, the Earth satellite population would remain relatively constant for only the next 50 years or so. Beyond that, the debris population would begin to increase noticeably, due to the production of collisional debris. Detailed analysis shows that this growth is primarily driven by high collision activities around 900 to 1000 km altitude - the region which has a very high concentration of debris at present. In reality, the satellite population growth in LEO will undoubtedly be worse than this study indicates, since spacecraft and their orbital stages will continue to be launched into space. Postmission disposal of vehicles (e.g., limiting postmission orbital lifetimes to less than 25 years) will help, but will be insufficient to constrain the Earth satellite population. To preserve better the near-Earth environment for future space activities, it might be necessary to remove existing large and massive objects from regions where high collision activities are

  6. Leo Szilard. Toward A Livable World.

    NASA Astrophysics Data System (ADS)

    Gerjuoy, Edward

    1998-04-01

    For essentially his entire adult life Leo Szilard sought to increase the likelihood that the results of basic scientific research, which especially since World War II have so greatly increased humanity's ability to manipulate the natural world, would be used for humanity's benefit. This talk will review and assess Szilard's endeavors in this quest, to which he so unwaveringly devoted his energies and talents. I also will reflect on the significance of that quest for this audience of scientists who, thirty four years after Szilard's death, have assembled today to honor him.

  7. Advanced propulsion for LEO and GEO platforms

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Pidgeon, David J.

    1990-01-01

    Mission requirements and mass savings applicable to specific low earth orbit and geostationary earth orbit platforms using three highly developed propulsion systems are described. Advanced hypergolic bipropellant thrusters and hydrazine arcjets can provide about 11 percent additional instrument payload to 14,000 kg LEO platforms. By using electric propulsion on a 8,000 kg class GEO platform, mass savings in excess of 15 percent of the beginning-of-life platform mass are obtained. Effects of large, advanced technology solar arrays and antennas on platform propulsion requirements are also discussed.

  8. The Leo I color-magnitude diagram

    NASA Astrophysics Data System (ADS)

    Reid, Neill; Mould, Jeremy

    1991-04-01

    The R-and I-band photometry of the Leo I dwarf galaxy is presented. A relatively narrow giant branch is found, Implying an abundance range of no more than Fe/H/= - 0.7 to - 1.3. This is in contrast to the results is found by Fox and Pritchet (1987) from BV CCD photometry. The distance modulus is estimated as (m - M) = 21.85 + or - 0.15, based on the luminosity of the tip of the red giant branch.

  9. POSSIBLE CHROMOSPHERIC ACTIVITY CYCLES IN AD LEO

    SciTech Connect

    Buccino, Andrea P.; Petrucci, Romina; Mauas, Pablo J. D.; Jofré, Emiliano

    2014-01-20

    AD Leo (GJ 388) is an active dM3 flare star that has been extensively observed both in the quiescent and flaring states. Since this active star is near the fully convective boundary, studying its long-term chromospheric activity in detail could be an appreciable contribution to dynamo theory. Here, using the Lomb-Scargle periodogram, we analyze the Ca II K line-core fluxes derived from CASLEO spectra obtained between 2001 and 2013 and the V magnitude from the ASAS database between 2004 and 2010. From both of these totally independent time series, we obtain a possible activity cycle with a period of approximately seven years and a less significant shorter cycle of approximately two years. A tentative interpretation is that a dynamo operating near the surface could be generating the longer cycle, while a second dynamo operating in the deep convection zone could be responsible for the shorter one. Based on the long duration of our observing program at CASLEO and the fact that we observe different spectral features simultaneously, we also analyze the relation between simultaneous measurements of the Na I index (R{sub D}{sup ′}), Hα, and Ca II K fluxes at different activity levels of AD Leo, including flares.

  10. LEO Flight Experience On MPS Batteries

    NASA Astrophysics Data System (ADS)

    Reulier, D.; Remy, S.; Mosset, E.; Carre, A.

    2011-10-01

    5 years after the qualification of the MPS176065 Li-ion battery for microsatellite, achieved with CNES Toulouse support, the module has been embedded on board several spacecrafts. The qualified module in 8S3P arrangement has been also derived in similar 7S3P, 6S1P and 8S6P flight configurations. The different battery configurations and associated missions will be presented, at the same time as flight status. Some missions are already finished and completed with success, whereas some others are running, or are to be launched. The proven sustainable levels and associated margins will be remembered with also a status of the life tests results (more than 63000 cycles achieved today in LEO typical mission conditions). Taking into account that more than 50 battery modules have been manufactured at the present time, the paper will describe main lessons learnt on the technical, process and industrial point of view. On orbit available and disclosable data will be shown to confirm the real performances and reliability of the MPS batteries. A specific chapter will present the comparison of some telemetry flight data correlated with SLIM software model predictions during LEO orbits. At the end of this presentation, a logical transition will emphasize the reasons for VES16 Li-ion cells development. It will include the main benefits given by the VES16 Li-ion cell compared to the current MPS cell especially aiming to extend the mission duration up to more than 12 years.

  11. Individual Pressure Vessel (PV) and Common Pressure Vessel (CPV) Nickel-Hydrogen Battery Performance Under LEO Cycling Conditions

    NASA Technical Reports Server (NTRS)

    Miller, Thomas B.; Lewis, Harlan L.

    2004-01-01

    LEO life cycle testing of Individual Pressure Vessel (PV) and Common Pressure Vessel (CPV) nickel-hydrogen cell packs have been sponsored by the NASA Aerospace Flight Battery Program. The cell packs have cycled under both 35% and 60% depth-of- discharge and temperature conditions of -5 C and +lO C. The packs have been on test since as early as 1992 and have generated a substantial database. This report will provide insight into performance trends as a function of the specific cell configuration and manufacturer for eight separate nickel-hydrogen battery cell packs.

  12. ISIS Electronics Flying on Korean LEO Satellites

    NASA Astrophysics Data System (ADS)

    Remy, S.; Mosset, E.; Park, Sungwoo

    2014-08-01

    Saft (Defense & Space, France), ASP (Advanced Space Power, Germany) and KARI (Korean Aerospace Research Institute, South Korea) developed an autonomous battery management system to carry out cell packages balancing, by-pass system activation and cell package discharge after failure detection. This high reliability electronics called ISIS (Intelligent Surveillance Integrated System) has been designed, tested and qualified in the frame of the Kompsat-3, Kompsat-5 and Kompsat-3A large LEO Korean KARI Satellites. Kompsat-3 and 3A (4.8 kWh battery) and Kompsat-5 (5.2 kWh battery equipped with a demanding imaging radar system) are powered during daily sun eclipses with respectively one 4P12S or 4P13S VES100 li-ion batteries managed by ISIS system.

  13. Eagle Class small satellite for LEO applications

    NASA Astrophysics Data System (ADS)

    O'Neil, Jason; Goralczyk, Steve

    1991-07-01

    The 'Eagle' Class small satellite is a modular Lightsat capable of supporting a wide variety of LEO applications. This paper highlights the key parameters of the spacecraft - power, stabilization, payload accommodation, etc., which make it useful as a platform for scientific experiments. The satellite consists of modules such as core, payload, deployables and orbit insertion subsystem which are integrated into a stacked configuration. The 38 in. diameter is sized for the Pegasus or Air Force SLV. Although considered a 'Lightsat', the satellite can offer as much as 500 watts of power and .01 degree attitude knowledge. It is suitable for a wide variety of earth observation and sensing missions. The satellite can be commanded by an economical desk-size Master Ground Station.

  14. Demonstration of Uncued Optical Surveillance of LEO

    NASA Astrophysics Data System (ADS)

    Zimmer, P.; Ackermann, M.; McGraw, J.

    2014-09-01

    J.T. McGraw and Associates, LLC, in collaboration with the University of New Mexico (UNM), has built and is operating two proof-of-concept wide-field imaging systems to test novel techniques for uncued surveillance of LEO. The imaging systems are built from off-the-shelf optics and detectors resulting in a 350mm aperture and a 6 square degree field of view. For streak detection, field of view is of critical importance because the maximum exposure time on the object is limited by its crossing time and measurements of apparent angular motion are better constrained with longer streaks. The current match of the detector to the optical system is optimized for detection of objects at altitudes above 450km, which for a circular orbit, corresponds to apparent motions of approximately 1 deg./sec. Using our GPU-accelerated detection scheme, the proof-of-concept systems have detected objects fainter than V=12.3, which approximately corresponds to a 24 cm object at 1000 km altitude at better than 6 sigma significance, from sites near and within Albuquerque, NM. This work demonstrates scalable optical systems designed for near real time detection of fast moving objects, which can be then handed off to other instruments capable of tracking and characterizing them. The two proof-of-concept systems, separated by ~30km, work together by taking simultaneous images of the same orbital volume to constrain the orbits of detected objects using parallax measurements. These detections are followed-up by photometric observations taken at UNM to independently assess the objects and the quality of the derived orbits. We believe this demonstrates the potential of small telescope arrays for detecting and cataloguing heretofore unknown LEO objects.

  15. LEO P: AN UNQUENCHED VERY LOW-MASS GALAXY

    SciTech Connect

    McQuinn, Kristen B. W.; Skillman, Evan D.; Berg, Danielle; Dolphin, Andrew; Cannon, John M.; Salzer, John J.; Rhode, Katherine L.; Adams, Elizabeth A. K.; Giovanelli, Riccardo; Haynes, Martha P.; Girardi, Léo

    2015-10-20

    Leo P is a low-luminosity dwarf galaxy discovered through the blind H i Arecibo Legacy Fast ALFA survey. The H i and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with active star formation, an underlying older population, and an extremely low oxygen abundance. We have obtained optical imaging with the Hubble Space Telescope to two magnitudes below the red clump in order to study the evolution of Leo P. We refine the distance measurement to Leo P to be 1.62 ± 0.15 Mpc, based on the luminosity of the horizontal branch stars and 10 newly identified RR Lyrae candidates. This places the galaxy at the edge of the Local Group, ∼0.4 Mpc from Sextans B, the nearest galaxy in the NGC 3109 association of dwarf galaxies of which Leo P is clearly a member. The star responsible for ionizing the H ii region is most likely an O7V or O8V spectral type, with a stellar mass ≳25 M{sub ⊙}. The presence of this star provides observational evidence that massive stars at the upper end of the initial mass function are capable of being formed at star formation rates as low as ∼10{sup −5} M{sub ⊙} yr{sup −1}. The best-fitting star formation history (SFH) derived from the resolved stellar populations of Leo P using the latest PARSEC models shows a relatively constant star formation rate over the lifetime of the galaxy. The modeled luminosity characteristics of Leo P at early times are consistent with low-luminosity dSph Milky Way satellites, suggesting that Leo P is what a low-mass dSph would look like if it evolved in isolation and retained its gas. Despite the very low mass of Leo P, the imprint of reionization on its SFH is subtle at best, and consistent with being totally negligible. The isolation of Leo P, and the total quenching of star formation of Milky Way satellites of similar mass, implies that the local environment dominates the quenching of the Milky Way satellites.

  16. Leo P: An Unquenched Very Low-mass Galaxy

    NASA Astrophysics Data System (ADS)

    McQuinn, Kristen B. W.; Skillman, Evan D.; Dolphin, Andrew; Cannon, John M.; Salzer, John J.; Rhode, Katherine L.; Adams, Elizabeth A. K.; Berg, Danielle; Giovanelli, Riccardo; Girardi, Léo; Haynes, Martha P.

    2015-10-01

    Leo P is a low-luminosity dwarf galaxy discovered through the blind H i Arecibo Legacy Fast ALFA survey. The H i and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with active star formation, an underlying older population, and an extremely low oxygen abundance. We have obtained optical imaging with the Hubble Space Telescope to two magnitudes below the red clump in order to study the evolution of Leo P. We refine the distance measurement to Leo P to be 1.62 ± 0.15 Mpc, based on the luminosity of the horizontal branch stars and 10 newly identified RR Lyrae candidates. This places the galaxy at the edge of the Local Group, ˜0.4 Mpc from Sextans B, the nearest galaxy in the NGC 3109 association of dwarf galaxies of which Leo P is clearly a member. The star responsible for ionizing the H ii region is most likely an O7V or O8V spectral type, with a stellar mass ≳25 M⊙. The presence of this star provides observational evidence that massive stars at the upper end of the initial mass function are capable of being formed at star formation rates as low as ˜10-5 M⊙ yr-1. The best-fitting star formation history (SFH) derived from the resolved stellar populations of Leo P using the latest PARSEC models shows a relatively constant star formation rate over the lifetime of the galaxy. The modeled luminosity characteristics of Leo P at early times are consistent with low-luminosity dSph Milky Way satellites, suggesting that Leo P is what a low-mass dSph would look like if it evolved in isolation and retained its gas. Despite the very low mass of Leo P, the imprint of reionization on its SFH is subtle at best, and consistent with being totally negligible. The isolation of Leo P, and the total quenching of star formation of Milky Way satellites of similar mass, implies that the local environment dominates the quenching of the Milky Way satellites. Based on observations made with the NASA/ESA Hubble Space Telescope (HST), obtained from the

  17. Leo Szilard In Physics and Information

    NASA Astrophysics Data System (ADS)

    Garwin, Richard

    2014-03-01

    The excellent biography by William Lanouette, ``Genius in the Shadows,'' tells it the way it was, incredible though it may seem. The 1972 ``Collected Works of Leo Szilard: Scientific Papers'' Bernard T. Feld and Getrude W. Szilard, Editors, gives the source material both published and unpublished. Szilard's path-breaking but initially little-noticed 1929 paper, ``On the Decrease of Entropy in a Thermodynamic System by the Intervention of Intelligent Beings'' spawned much subsequent research. It connected what we now call a bit of information with a quantity k ln 2 of entropy, and showed that the process of acquiring, exploiting, and resetting this information in a one-molecule engine must dissipate at least kT ln 2 of energy at temperature T. His 1925 paper, ``On the Extension of Phenomenological Thermodynamics to Fluctuation Phenomena,'' showed that fluctuations were consistent with and predicted from equilibrium thermodynamics and did not depend on atomistic theories. His work on physics and technology, demonstrated an astonishing range of interest, ingenuity, foresight, and practical sense. I illustrate this with several of his fundamental contributions nuclear physics, to the neutron chain reaction and to nuclear reactors, and also to electromagnetic pumping of liquid metals.

  18. The Fornax-Leo-Sculptor stream revisited

    NASA Astrophysics Data System (ADS)

    Majewski, Steven R.

    1994-08-01

    Lynden-Bell first demonstrated that the satellites of the Milky Way appear situated along two great 'streams' in the sky: the 'Magellanic stream' and the 'Fornax-Leo-Sculptor (FLS) stream.' Further exploration of the three-dimensional distribution of Galactic satellites reveals that the recently discovered Sextans and Phoenix dwarf spheroidal galaxies also lie near the plane defined by the FLS galaxies, and therefore strengthens the evidence in favor of the FLS stream. Moreover, a specific group of globular clusters -- those exhibiting the reddest horizontal branches (HBs) among those identified as 'young halo' by Zinn -- appear to populate the FLS stream. As previously demonstrated by Zinn, the spatial distribution of old halo globulars appears to be flattened toward the Galactic plane, and therefore the old halo clusters are typically anti-correlated to the nearly orthogonal FLS stream. A scenario is postulated wherein the Galactic satellites of the FLS stream and the red HB, young halo globular clusters share a common origin in the accretion of a formerly larger, parent satellite galaxy or Searle & Zinn 'fragment.'

  19. The Fornax-Leo-Sculptor stream revisited

    NASA Technical Reports Server (NTRS)

    Majewski, Steven R.

    1994-01-01

    Lynden-Bell first demonstrated that the satellites of the Milky Way appear situated along two great 'streams' in the sky: the 'Magellanic stream' and the 'Fornax-Leo-Sculptor (FLS) stream.' Further exploration of the three-dimensional distribution of Galactic satellites reveals that the recently discovered Sextans and Phoenix dwarf spheroidal galaxies also lie near the plane defined by the FLS galaxies, and therefore strengthens the evidence in favor of the FLS stream. Moreover, a specific group of globular clusters -- those exhibiting the reddest horizontal branches (HBs) among those identified as 'young halo' by Zinn -- appear to populate the FLS stream. As previously demonstrated by Zinn, the spatial distribution of old halo globulars appears to be flattened toward the Galactic plane, and therefore the old halo clusters are typically anti-correlated to the nearly orthogonal FLS stream. A scenario is postulated wherein the Galactic satellites of the FLS stream and the red HB, young halo globular clusters share a common origin in the accretion of a formerly larger, parent satellite galaxy or Searle & Zinn 'fragment.'

  20. Leishmania infantum infection in two captive barbary lions (Panthera leo leo).

    PubMed

    Libert, Cédric; Ravel, Christophe; Pratlong, Francine; Lami, Patrick; Dereure, Jacques; Keck, Nicolas

    2012-09-01

    A female barbary lion (Panthera leo leo) from the Montpellier Zoological Park (France) showing colitis, epistaxis, and lameness with pad ulcers was positive by polymerase chain reaction (PCR) for Leishmania infantum. Further indirect immunofluorescence (IFAT) tests on the banked sera from all lions of the park detected another infected but asymptomatic female, which was confirmed by PCR on ethylenediaminetetraacetic acid (EDTA) blood sample. Leishmania infantum zymodeme MON-1 was cultured from EDTA bone marrow samples sampled from this second animal. The first female was successfully treated with marbofloxacine at 2 mg/kg s.i.d. for 28 days (Marbocyl, Vetoquinol 70204 Lure, France) and allopurinol at 30 mg/kg s.i.d. for 3 mo (Allopurinol Mylan, Mylan SAS, 69800 Saint-Priest, France) and then 1 wk/mo. Both positive animals were born at the Rabat Zoological Park, Morocco, and arrived together at Montpellier in 2003. The chronicity and source of this current infection are unknown since Morocco and southern France are well-known to be enzootic for leishmaniasis.

  1. LoWMob: Intra-PAN Mobility Support Schemes for 6LoWPAN.

    PubMed

    Bag, Gargi; Raza, Muhammad Taqi; Kim, Ki-Hyung; Yoo, Seung-Wha

    2009-01-01

    Mobility in 6LoWPAN (IPv6 over Low Power Personal Area Networks) is being utilized in realizing many applications where sensor nodes, while moving, sense and transmit the gathered data to a monitoring server. By employing IEEE802.15.4 as a baseline for the link layer technology, 6LoWPAN implies low data rate and low power consumption with periodic sleep and wakeups for sensor nodes, without requiring them to incorporate complex hardware. Also enabling sensor nodes with IPv6 ensures that the sensor data can be accessed anytime and anywhere from the world. Several existing mobility-related schemes like HMIPv6, MIPv6, HAWAII, and Cellular IP require active participation of mobile nodes in the mobility signaling, thus leading to the mobility-related changes in the protocol stack of mobile nodes. In this paper, we present LoWMob, which is a network-based mobility scheme for mobile 6LoWPAN nodes in which the mobility of 6LoWPAN nodes is handled at the network-side. LoWMob ensures multi-hop communication between gateways and mobile nodes with the help of the static nodes within a 6LoWPAN. In order to reduce the signaling overhead of static nodes for supporting mobile nodes, LoWMob proposes a mobility support packet format at the adaptation layer of 6LoWPAN. Also we present a distributed version of LoWMob, named as DLoWMob (or Distributed LoWMob), which employs Mobility Support Points (MSPs) to distribute the traffic concentration at the gateways and to optimize the multi-hop routing path between source and destination nodes in a 6LoWPAN. Moreover, we have also discussed the security considerations for our proposed mobility schemes. The performance of our proposed schemes is evaluated in terms of mobility signaling costs, end-to-end delay, and packet success ratio.

  2. TT and C - First TDRSS, Then Commercial GEO and Big LEO and Now through LEO

    NASA Technical Reports Server (NTRS)

    Morgan, Dwayne; Bull, Barton; Grant, Charles; Streich, Ronald; Powers, Edward I. (Technical Monitor)

    2001-01-01

    The advent of low earth orbit (LEO) commercial communications satellites provides an opportunity to dramatically reduce Telemetry Tracking and Control (TT&C) costs of launch vehicles and Unpiloted Aerial Vehicles (UAVs) by reducing or eliminating ground infrastructure. Personnel from the Goddard Space Flight Center Wallops Flight Facility (GSFC/WFF) in Virginia have successfully used commercial GEO & Big LEO communications satellites for Long Duration Balloon flight TT&C. In addition, TDRSS capability for these balloons has been developed by WFF for the Ultra Long Duration Balloons with the first test flight launch in January 2001 for one global circumnavigation at 120,000 feet altitude launched from Alice Springs. Australia. Numerous other low cost applications can new utilize the commercial LEO satellites for TT&C. The Flight Modern became a GSFC/WFF Advanced Range Technology Initiative (ARTI) in an effort to streamline TT&C capability to the user community at low cost. Phase I ground tests of The Flight Modem verified downlink communications quality of service and measured transmission latencies. These tests were completed last year, Phase II consisting of aircraft flight tests provide much of the data presented in this paper. Phase III of the Flight Modern baseline test program is a demonstration of the ruggedized version of the WFF Flight Modem flown on one sounding rocket launched from Sweden. Flights of opportunity have been and are being actively pursued with other centers, ranges and users at universities. The WFF goal is to reduce TT&C costs by providing a low cost COTS Flight Modem with a User Handbook containing system capability and limitation descriptions. Additionally, since data transmission is by packetized Internet Protocol (IP), data can be received and commands initialed from practically any location with no infrastructure. The WFF, like most ranges, has been using GPS receivers on sounding rockets and long duration balloons for several years

  3. System using leo satellites for centimeter-level navigation

    NASA Technical Reports Server (NTRS)

    Rabinowitz, Matthew (Inventor); Parkinson, Bradford W. (Inventor); Cohen, Clark E. (Inventor); Lawrence, David G. (Inventor)

    2002-01-01

    Disclosed herein is a system for rapidly resolving position with centimeter-level accuracy for a mobile or stationary receiver [4]. This is achieved by estimating a set of parameters that are related to the integer cycle ambiguities which arise in tracking the carrier phase of satellite downlinks [5,6]. In the preferred embodiment, the technique involves a navigation receiver [4] simultaneously tracking transmissions [6] from Low Earth Orbit Satellites (LEOS) [2] together with transmissions [5] from GPS navigation satellites [1]. The rapid change in the line-of-sight vectors from the receiver [4] to the LEO signal sources [2], due to the orbital motion of the LEOS, enables the resolution with integrity of the integer cycle ambiguities of the GPS signals [5] as well as parameters related to the integer cycle ambiguity on the LEOS signals [6]. These parameters, once identified, enable real-time centimeter-level positioning of the receiver [4]. In order to achieve high-precision position estimates without the use of specialized electronics such as atomic clocks, the technique accounts for instabilities in the crystal oscillators driving the satellite transmitters, as well as those in the reference [3] and user [4] receivers. In addition, the algorithm accommodates as well as to LEOS that receive signals from ground-based transmitters, then re-transmit frequency-converted signals to the ground.

  4. PECULIAR VELOCITIES OF GALAXIES IN THE LEO SPUR

    SciTech Connect

    Karachentsev, Igor D.; Makarova, Lidia N.; Makarov, Dmitry I.; Tully, R. Brent; Rizzi, Luca

    2015-06-01

    The Hubble Space Telescope Advanced Camera for Surveys has been used to determine accurate distances for the spiral galaxy NGC 2683 and 12 other galaxies in a zone of the “local velocity anomaly” from luminosity measurements of the brightest red giant branch stars. These galaxies lie in the Leo Spur, the nearest filament beyond our Local Sheet. The new accurate distance measurements confirm that galaxies along the Leo Spur are more distant than expected from uniform cosmic expansion, and hence have large and peculiar velocities toward us. The motions are generally explained by a previously published model that posits that the Local Sheet is descending at 259 km s{sup −1} toward the south supergalactic pole due to expansion of the Local Void and is being attracted toward the Virgo Cluster at 185 km s{sup −1}. With the standard ΛCDM cosmology, an empty void expands at 16 km s{sup −1} Mpc{sup −1}, so a motion of 259 km s{sup −1} requires the Local Void to be impressively large and empty. Small residuals from the published model can be attributed to an upward push toward the north supergalactic pole by the expansion of the Gemini–Leo Void below the Leo Spur. The Leo Spur is sparsely populated, but among its constituents there are two associations that contain only dwarf galaxies.

  5. A Novel Spacecraft Charge Monitor for LEO

    NASA Technical Reports Server (NTRS)

    Goembel, Luke

    2004-01-01

    Five years ago we introduced a new method for measuring spacecraft chassis floating potential relative to the space plasma (absolute spacecraft potential) in low Earth orbit. The method, based on a straightforward interpretation of photoelectron spectra, shows promise for numerous applications, but has not yet been tried. In the interest of testing the method, and ultimately supplying another tool for measuring absolute spacecraft charge, we are producing a flight prototype Spacecraft Charge Monitor (SCM) with support from NASA's Small Business Innovation Research (SBIR) program. Although insight into the technique came from data collected in space over two decades ago, very little data are available. The data indicate that it may be possible to determine spacecraft floating potential to within 0.1 volt each with the SCM second under certain conditions. It is debatable that spacecraft floating potential has ever been measured with such accuracy. The compact, easily deployed SCM also offers the advantage of long-term stability in calibration. Accurate floating potential determinations from the SCM could be used to correct biases in space plasma measurements and evaluate charge mitigation and/or sensing devices. Although this paper focuses on the device's use in low Earth orbit (LEO), the device may also be able to measure spacecraft charge at higher altitudes, in the solar wind, and in orbits around other planets. The flight prototype SCM we are producing for delivery to NASA in the third quarter of 2004 will measure floating potential from 0 to -150 volts with 0.1 volt precision, weigh approximately 600-700 grams, consume approximately 2 watts, and will measure approximately 8 x 10 x 17 cm.

  6. Malignant lymphoma in african lions (panthera leo).

    PubMed

    Harrison, T M; McKnight, C A; Sikarskie, J G; Kitchell, B E; Garner, M M; Raymond, J T; Fitzgerald, S D; Valli, V E; Agnew, D; Kiupel, M

    2010-09-01

    Malignant lymphoma has become an increasingly recognized problem in African lions (Panthera leo). Eleven African lions (9 male and 2 female) with clinical signs and gross and microscopic lesions of malignant lymphoma were evaluated in this study. All animals were older adults, ranging in age from 14 to 19 years. Immunohistochemically, 10 of the 11 lions had T-cell lymphomas (CD3(+), CD79a(-)), and 1 lion was diagnosed with a B-cell lymphoma (CD3(-), CD79a(+)). The spleen appeared to be the primary site of neoplastic growth in all T-cell lymphomas, with involvement of the liver (6/11) and regional lymph nodes (5/11) also commonly observed. The B-cell lymphoma affected the peripheral lymph nodes, liver, and spleen. According to the current veterinary and human World Health Organization classification of hematopoietic neoplasms, T-cell lymphoma subtypes included peripheral T-cell lymphoma (4/11), precursor (acute) T-cell lymphoblastic lymphoma/leukemia (2/11), chronic T-cell lymphocytic lymphoma/leukemia (3/11), and T-zone lymphoma (1/11). The single B-cell lymphoma subtype was consistent with diffuse large B-cell lymphoma. Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) testing by immunohistochemistry on sections of malignant lymphoma was negative for all 11 lions. One lion was seropositive for FeLV. In contrast to domestic and exotic cats, in which B-cell lymphomas are more common than T-cell lymphomas, African lions in this study had malignant lymphomas that were primarily of T-cell origin. Neither FeLV nor FIV, important causes of malignant lymphoma in domestic cats, seems to be significant in the pathogenesis of malignant lymphoma in African lions.

  7. An Update on the Effectiveness of Postmission Disposal in LEO

    NASA Technical Reports Server (NTRS)

    Liou, J.-C; Krisko, Paula

    2013-01-01

    Orbital debris mitigation measures have been developed to reduce the growth of the future debris population by the international space community over the past two decades. A major component in the overall mitigation strategy is postmission disposal (PMD). A key PMD element for the low Earth orbit (LEO, the region below 2000 km altitude) satellites is the 25-year decay rule. It is intended to limit the long-term presence of massive intact objects - rocket bodies (R/Bs) and spacecraft (S/C) in the environment. The effectiveness of the 25-year rule was well demonstrated and documented during the development of the mitigation measures. The orbital debris population in LEO, unfortunately, has significantly increased since that time. The objectives of this paper are to provide an updated assessment based on the 2012 LEO environment and to highlight the importance of the global compliance of the 25-year decay rule.

  8. The Littoral Environment Observation (LEO) Data Collection Program.

    DTIC Science & Technology

    1981-03-01

    C SCHNEIDER UNCLASSIFIED ERC- CETA -81-5 NL * EEEEEEEEEEEEIBlag~lli/lii ND CETA 81-5 The Littoral Environment Observation ’. (LEO) Data Collection...E 2. GOVT ACCESSION NO. 3. RECIPIENT’S CATALOG NUMBER - CETA -81-5 / 4. TITLE (and Sublitle) S. TYPE OF REPORT 4 PERIOD COVERED/ , oas tal...pp. 2WALTON, T.L., Jr., "Computation of Longshore Energy using LEO Current Observations," CETA 80-3, U.S. Army, Corps of Engineers, Coastal

  9. Leo I - The youngest Milky Way dwarf spheroidal galaxy?

    NASA Technical Reports Server (NTRS)

    Lee, Myung G.; Freedman, Wendy; Mateo, Mario; Thompson, Ian; Roth, Miguel; Ruiz, Maria-Teresa

    1993-01-01

    Deep CCD photometry of about 16,000 stars in the Milky Way's Leo I spheroidal galaxy satellite is reported. An account is given of the features observed in the color-magnitude diagrams (CMDs) derived therefrom. A very blue and well-defined red giant branch (RGB) is noted. The CMDs of Leo I shows about 50 anomalous Cepheid candidates; there are another 50 or so asymptotic giant branch stars above the tip of the RGB, including 15 known carbon stars. The mean color of the RGB is estimated at M sub I = -3.5 mag.

  10. Variable stars in the Leo A dwarf galaxy (DDO 69)

    NASA Technical Reports Server (NTRS)

    Hoessel, John G.; Saha, A.; Krist, John; Danielson, G. Edward

    1994-01-01

    Observations of the Leo A dwarf galaxy, obtained over the period from 1980 to 1991 are reported. Forty two separate Charge Coupled Devices (CCD) frames were searched for variable stars. A total of 14 suspected variables were found, 9 had sufficient coverage for period determination, and 5 had Cepheid light curves. Four of these stars fit well on a P-L relation and yield a distance modulus, after correction for Galactic foreground extinction, of m-M = 26.74. This corresponds to a distance of 2.2 Mpc, placing Leo A near the Local Group zero-velocity surface.

  11. PRECISION POINTING OF IBEX-Lo OBSERVATIONS

    SciTech Connect

    Hlond, M.; Bzowski, M.; Moebius, E.; Kucharek, H.; Heirtzler, D.; Schwadron, N. A.; Neill, M. E. O'; Clark, G.; Crew, G. B.; Fuselier, S.; McComas, D. J. E-mail: eberhard.moebius@unh.edu E-mail: stephen.a.fuselier@linco.com E-mail: DMcComas@swri.edu

    2012-02-01

    Post-launch boresight of the IBEX-Lo instrument on board the Interstellar Boundary Explorer (IBEX) is determined based on IBEX-Lo Star Sensor observations. Accurate information on the boresight of the neutral gas camera is essential for precise determination of interstellar gas flow parameters. Utilizing spin-phase information from the spacecraft attitude control system (ACS), positions of stars observed by the Star Sensor during two years of IBEX measurements were analyzed and compared with positions obtained from a star catalog. No statistically significant differences were observed beyond those expected from the pre-launch uncertainty in the Star Sensor mounting. Based on the star observations and their positions in the spacecraft reference system, pointing of the IBEX satellite spin axis was determined and compared with the pointing obtained from the ACS. Again, no statistically significant deviations were observed. We conclude that no systematic correction for boresight geometry is needed in the analysis of IBEX-Lo observations to determine neutral interstellar gas flow properties. A stack-up of uncertainties in attitude knowledge shows that the instantaneous IBEX-Lo pointing is determined to within {approx}0.{sup 0}1 in both spin angle and elevation using either the Star Sensor or the ACS. Further, the Star Sensor can be used to independently determine the spacecraft spin axis. Thus, Star Sensor data can be used reliably to correct the spin phase when the Star Tracker (used by the ACS) is disabled by bright objects in its field of view. The Star Sensor can also determine the spin axis during most orbits and thus provides redundancy for the Star Tracker.

  12. Satellite Telemetry and Command using Big LEO Mobile Telecommunications Systems

    NASA Technical Reports Server (NTRS)

    Huegel, Fred

    1998-01-01

    Various issues associated with satellite telemetry and command using Big LEO mobile telecommunications systems are presented in viewgraph form. Specific topics include: 1) Commercial Satellite system overviews: Globalstar, ICO, and Iridium; 2) System capabilities and cost reduction; 3) Satellite constellations and contact limitations; 4) Capabilities of Globalstar, ICO and Iridium with emphasis on Globalstar; and 5) Flight transceiver issues and security.

  13. Sowing the Seeds of the Autism Field: Leo Kanner (1943)

    ERIC Educational Resources Information Center

    Blacher, Jan; Christensen, Lisa

    2011-01-01

    More than 65 years after Leo Kanner published his seminal article, research on autism continues to be an area of increasing interest. Although much progress has been made, this field is still in its infancy, and many avenues of research are just beginning to be pursued. Despite the time that has passed, the syndrome Kanner identified and his…

  14. Neoconservatism and Leo Strauss: The Place of a Liberal Education

    ERIC Educational Resources Information Center

    York, J. G.

    2008-01-01

    This paper is concerned with the work of Leo Strauss, specifically his two essays on liberal education. Strauss is often claimed to be a founding thinker of neoconservatism and while much scholarship has been produced analyzing his work, very little discusses his essays on liberal education and how these fit within his larger project. This essay…

  15. Severe intestinal coccidiosis in a newborn lion (Panthera leo)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Severe coccidiosis was found in sections of small intestine of a less than 2 day old lion (Panthera leo) born in captivity. Schizonts, merozoites, gamonts, and unsporulated oocysts were located in epithelial cells of ileum. Ultrastructural examination indicated that schizonts divided by schizogony. ...

  16. Complete mitochondrial genome of a Asian lion (Panthera leo goojratensis).

    PubMed

    Li, Yu-Fei; Wang, Qiang; Zhao, Jian-ning

    2016-01-01

    The entire mitochondrial genome of this Asian lion (Panthera leo goojratensis) was 17,183 bp in length, gene composition and arrangement conformed to other lions, which contained the typical structure of 22 tRNAs, 2 rRNAs, 13 protein-coding genes and a non-coding region. The characteristic of the mitochondrial genome was analyzed in detail.

  17. Exploiting link dynamics in LEO-to-ground communications

    SciTech Connect

    Palmer, Joseph Mcrae; Caffrey, Michael P

    2009-01-01

    The high dynamics of the LEO-to-ground radio channel are described. An analysis shows how current satellite radio systems largely underutilize the available radio link, and that a radio that can adaptively vary the bit rate can more fully exploit it, resulting in increased data throughput and improved power efficiency. We propose one method for implementing the adaptivity, and present simulation results.

  18. Hierarchical Supervisor and Agent Routing Algorithm in LEO/MEO Double-layered Optical Satellite Network

    NASA Astrophysics Data System (ADS)

    Li, Yongjun; Zhao, Shanghong

    2016-09-01

    A novel routing algorithm (Hierarchical Supervisor and Agent Routing Algorithm, HSARA) for LEO/MEO (low earth orbit/medium earth orbit) double-layered optical satellite network is brought forward. The so-called supervisor (MEO satellite) is designed for failure recovery and network management. LEO satellites are grouped according to the virtual managed field of MEO which is different from coverage area of MEO satellite in RF satellite network. In each LEO group, one LEO satellite which has maximal persistent link with its supervisor is called the agent. A LEO group is updated when this optical inter-orbit links between agent LEO satellite and the corresponding MEO satellite supervisor cuts off. In this way, computations of topology changes and LEO group updating can be decreased. Expense of routing is integration of delay and wavelength utilization. HSARA algorithm simulations are implemented and the results are as follows: average network delay of HSARA can reduce 21 ms and 31.2 ms compared with traditional multilayered satellite routing and single-layer LEO satellite respectively; LEO/MEO double-layered optical satellite network can cover polar region which cannot be covered by single-layered LEO satellite and throughput is 1% more than that of single-layered LEO satellite averagely. Therefore, exact global coverage can be achieved with this double-layered optical satellite network.

  19. The Evolution of Starspots on LO Pegasi

    NASA Astrophysics Data System (ADS)

    Harmon, Robert O.; Cochran, Mallory; Shank, Derek; Sweeney, Nicholas; Vesa, Oana

    2017-01-01

    LO Pegasi is an ultrarotator (P = 10.1538 hr) and young solar analog that exibits large starspots on its surface. Starspots are regions of strong magnetic field analogous to sunspots that inhibit convective transport of energy from deeper layers, causing the spots to be cooler and thus darker than the surrounding photosphere. The star's brightness varies as the spots are carried into and out of view of Earth by the star's rotation, so that photometry can provide insight into their characteristics. The amount of rotational modulation depends on the sizes, shapes, and locations of the spots, along with the inclination of the rotation axis to the line of sight, the brightness contrast between the spots and the rest of the surface, and the amount of limb darkening. The brightness contrast and limb darkening differ amond different photometric filter passbands, such that multi-filter observations provide additional information about spot latitudes compared to single-filter observations. We present surface images of LO Pegasi based on an indirect light-curve inversion algorithm applied to BVRI photometry obtained at Perkins Observatory in Delaware, OH from 2006-2016, which include variations in the size of a polar spot deduced from year-to-year variations in the star's average brightness.

  20. Lo Gnomone Clementino Astronomia Meridiana in Basilica

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino

    2014-05-01

    Costruito per chiara volontà del papa 70 anni dopo il caso Galileo, lo Gnomone Clementino è un grande telescopio solare che non fa uso di lenti a 92 anni dall’invenzione del cannocchiale. Queste due caratteristiche basterebbero da sole a giustificare l’interesse verso questo strumento. L’astronomia meridiana è alla base dell’astrometria e dell’astrofisica moderna. Lo Gnomone Clementino sta oggi all’astronomia, come il veliero “Amerigo Vespucci” sta alla Marina Italiana. E’ possibile svolgere ogni genere di osservazione e studio su questo strumento, e dal 2002 vi tengo lezioni teorico-pratiche del corso di Storia dell’Astronomia e La Terra nel Sistema Solare della Sapienza, Università di Roma, Facoltà di Lettere e Filosofia. Questo testo aggiunge alcuni tasselli alla ricerca storica sulla meridiana, appoggiandosi, com’è naturale, sulle spalle di giganti che mi hanno preceduto in questi studi. In particolare la misura dell’azimut della meridiana, ed il suo inquadramento tra gli strumenti simili ed alcuni studi di astrometria sui dati del 1701-1703 di Bianchini, che sono apparsi fin’ora soltanto su riviste specializzate ed in Inglese vengono qui proposti in Italiano e semplificati, per valorizzare sempre più questa straordinaria opera d’arte e di scienza.

  1. Agreement between Saint Leo College, Inc. and United Faculty of Saint Leo College, United Faculty of Florida, NEA, October 19, 1983-June 2, 1985.

    ERIC Educational Resources Information Center

    National Education Association, Washington, DC.

    The collective bargaining agreement between Saint Leo College and the United Faculty of Saint Leo College/United Faculty of Florida Chapter (43 members) of the National Education Association covering the period October 19, 1983-June 2, 1985 is presented. Items covered in the agreement include: unit recognition, definitions, management and union…

  2. Leo Szilard: Physics, Politics, and the Narrow Margin of Hope.

    NASA Astrophysics Data System (ADS)

    Lanouette, William

    1998-04-01

    Leo Szilard (1898-1964) was a creative physicist and biologist. But concern about how scientific discoveries might affect humanity also led him to seek political solutions to enlarge the benefits and limit the damage caused by his work. This disposition to save the world came to Szilard by the age of 10, when he read The Tragedy of Man, a Hungarian epic poem in which humanity faces extinction yet continues to survive by maintaining a narrow margin of hope. With this hope Szilard brought about improbable scientific and political feats (such as the nuclear chain reaction and the Moscow-Washington Hotline). This talk focuses on Szilard's many attempts in 1945 to prevent the atomic bombing of Japan. William Lanouette, a writer and public policy analyst, is the author of Genius in the Shadows: A Biography of Leo Szilard, The Man Behind the Bomb. (University of Chicago Press, 1994)

  3. Arcing in Leo and Geo Simulated Environments: Comparative Analysis

    NASA Technical Reports Server (NTRS)

    Vayner, Boris V.; Ferguson, Dale C.; Galofaro, Joel TY.

    2006-01-01

    Comprehensive tests of two solar array samples in simulated Low Earth Orbit (LEO) and Geosynchronous Orbit (GEO) environments have demonstrated that the arc inception voltage was 2-3 times lower in the LEO plasma than in the GEO vacuum. Arc current pulse wave forms are also essentially different in these environments. Moreover, the wide variations of pulse forms do not allow introducing the definition of a "standard arc wave form" even in GEO conditions. Visual inspection of the samples after testing in a GEO environment revealed considerable damage on coverglass surfaces and interconnects. These harmful consequences can be explained by the discharge energy being one order of magnitude higher in vacuum than in background plasma. The tests also revealed a potential danger of powerful electrostatic discharges that could be initiated on the solar array surface of a satellite in GEO during the ignition of an arcjet thruster.

  4. High-voltage plasma interactions calculations using NASCAP/LEO

    NASA Technical Reports Server (NTRS)

    Mandell, M. J.; Katz, I.

    1990-01-01

    This paper reviews four previous simulations (two laboratory and two space-flight) of interactions of a high-voltage spacecraft with a plasma under low-earth orbit conditions, performed using a three-dimensional computer code NASCAP/LEO. Results show that NASCAP/LEO can perform meaningful simulations of high-voltage plasma interactions taking into account three-dimensional effects of geometry, spacecraft motion, and magnetic field. Two new calculations are presented: (1) for current collection by 1-mm pinholes in wires (showing that a pinhole in a wire can collect far more current than a similar pinhole in a flat plate); and (2) current collection by Charge-2 mother vehicle launched in December 1985. It is shown that the Charge-2 calculations predicted successfully ion collection at negative bias, the floating potential of a probe outside or inside the sheath under negative bias conditions, and magnetically limited electron collection under electron beam operation at high altitude.

  5. LEO high voltage solar array arcing response model, continuation 5

    NASA Technical Reports Server (NTRS)

    Metz, Roger N.

    1989-01-01

    The modeling of the Debye Approximation electron sheaths in the edge and strip geometries was completed. Electrostatic potentials in these sheaths were compared to NASCAP/LEO solutions for similar geometries. Velocity fields, charge densities and particle fluxes to the biased surfaces were calculated for all cases. The major conclusion to be drawn from the comparisons of our Debye Approximation calculations with NASCAP-LEO output is that, where comparable biased structures can be defined and sufficient resolution obtained, these results are in general agreement. Numerical models for the Child-Langmuir, high-voltage electron sheaths in the edge and strip geometries were constructed. Electrostatic potentials were calculated for several cases in each of both geometries. Velocity fields and particle fluxes were calculated. The self-consistent solution process was carried through one cycle and output electrostatic potentials compared to NASCAP-type input potentials.

  6. A novel unicast routing algorithm for LEO satellite networks

    NASA Astrophysics Data System (ADS)

    Song, Xuegui; Liu, Kai; Zhang, Jun; Cheng, Lianzhen

    2005-11-01

    One of research challenges in low earth orbit (LEO) satellite networks is to develop specialized and efficient routing algorithms. In this paper, a dynamic source routing algorithm (DSRA) for LEO satellite networks is presented to achieve short end-to-end delay and low computation overhead under the condition that a logical location concept is adopted to hide satellite mobility. In this algorithm, the path between source and destination with minimum propagation delay is designated by source satellite in packet header by an efficient metric < D0, n0; D1, n1; D2, n2 >. Then the packet is forwarded to its destination by intermediate nodes according to the metric. The performance of the algorithm is evaluated through simulation and its computation complexity is analyzed to validate algorithm efficiency.

  7. LEO test data for 81 Ah FNC cells

    SciTech Connect

    Anderman, M.; Cohen, F.

    1997-12-01

    LEO test data for 81 Ah Fiber Nickel-Cadmium (FNC) battery packs are presented. Trends in pressure, charge acceptance, discharge voltage, capacity, and impedance during 7,800, 60% DOD cycles will be discussed. It will be shown that the FNC is capable of high rate discharge and fast charge to high DOD with stable performance. The relationship between cell design and battery pack performance will also be discussed.

  8. Starspots on LO Pegasi, 2006-2014

    NASA Astrophysics Data System (ADS)

    Harmon, Robert O.; Berry, Dominique; Chalmers, Mark; Denison, Josh; Stevens, Don; Yuhas, Kaylee

    2015-01-01

    BVRI light curves of LO Pegasi obtained at Perkins Observatory (Ohio Wesleyan University) from 2006-2014 were used to study the evolution of starspots on its surface over that interval. We present surface maps obtained via a constrained non-linear inversion algorithm that uses variations in limb darkening as seen through different filters to improve the latitude resolution of the reconstructions. In addition, a detailed period analysis of the entire data set using the ANOVA method was performed to search for variations associated with differential rotation. No evidence of period change was found, as the periods for each year were equal to within their uncertainties. For the data set as a whole, the period of rotation was determined to be 10.1538 ± 0.0009 hr, in agreement with previously published results.

  9. Starspots on LO Pegasi, 2006-2015

    NASA Astrophysics Data System (ADS)

    Harmon, Robert O.; Chalmers, Mark; Geda, Robel; Henry, Brandi; Sliupas, Viesulas

    2016-01-01

    LO Pegasi is a rapidly rotating (P = 10.154 hr) young solar analog (spectral class K5-7V) variable star of BY Dra type that exhibits dark starspots on its surface that modulate its brightness as they are carried into and out of view by the star's rotation. Surface maps of the spot distribution were produced based on BVRI photometry obtained at Perkins Observatory from 2006-2015. The maps were generated from the light curves via a non-linear inversion algorithm that uses the differences in the limb darkening through different filter passbands to improve the latitude resolution of the maps. We present an analysis of variations in the size of a polar spot suggested by changes in the average brightness and the amplitude of the rotational modulation from year to year.

  10. Reinforcement learning for resource allocation in LEO satellite networks.

    PubMed

    Usaha, Wipawee; Barria, Javier A

    2007-06-01

    In this paper, we develop and assess online decision-making algorithms for call admission and routing for low Earth orbit (LEO) satellite networks. It has been shown in a recent paper that, in a LEO satellite system, a semi-Markov decision process formulation of the call admission and routing problem can achieve better performance in terms of an average revenue function than existing routing methods. However, the conventional dynamic programming (DP) numerical solution becomes prohibited as the problem size increases. In this paper, two solution methods based on reinforcement learning (RL) are proposed in order to circumvent the computational burden of DP. The first method is based on an actor-critic method with temporal-difference (TD) learning. The second method is based on a critic-only method, called optimistic TD learning. The algorithms enhance performance in terms of requirements in storage, computational complexity and computational time, and in terms of an overall long-term average revenue function that penalizes blocked calls. Numerical studies are carried out, and the results obtained show that the RL framework can achieve up to 56% higher average revenue over existing routing methods used in LEO satellite networks with reasonable storage and computational requirements.

  11. NASA-STD-4005 and NASA-HDBK-4006, LEO Spacecraft Solar Array Charging Design Standard

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.

    2007-01-01

    Two new NASA Standards are now official. They are the NASA LEO Spacecraft Charging Design Standard (NASA-STD-4005) and the NASA LEO Spacecraft Charging Design Handbook (NASA-HDBK-4006). They give the background and techniques for controlling solar array-induced charging and arcing in LEO. In this paper, a brief overview of the new standards is given, along with where they can be obtained and who should be using them.

  12. An Update on the Effectiveness of Postmission Disposal in LEO

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.

    2013-01-01

    The commonly-adopted orbital debris mitigation measures were developed to reduce the growth of the future debris population. A major component in debris mitigation is post-mission disposal (PMD). The key PMD element for LEO satellites is the 25-year rule. It is intended to limit the long-term presence of rocket bodies (R/Bs) and spacecraft (S/C), as well as mission-related debris, in the environment. The effectiveness of PMD has been demonstrated and documented since the development of mitigation measures began in the 1990s. This paper summarizes an updated study, based on the current environment, using the NASA LEGEND model. The study focused on the > or = 10 cm population in LEO. The historical simulation covered 1957 through 2011 and followed the recorded launches and known breakup events. The future projection was carried out for 200 years. An eight-year launch traffic, 2004 - 2011, was repeated during the projection period. An eight-year mission lifetime was assumed for future S/C. No stationkeeping and no collision avoidance maneuver were implemented. Only objects 10 cm and larger were included in collision consideration. No explosion was allowed for R/Bs and S/C launched after 2011. The 25-year PMD rule success rates were set at 0%, 10%, 50%, 75%, and 95%, respectively, for the 5 study scenarios. Results of the simulations were analyzed to quantify the differences among the different compliance rates. As expected, the 0% PMD projection followed a rapid and non-linear increase in the next 200 years. The LEO population, on average, more than tripled at the end of the simulations. With a 50% compliance of the 25-year rule, the population growth was reduced approximately by half. However, even with a 95% compliance of the 25-year rule, the LEO debris population would still increase by an average of more than 50% in 200 years. These simulation results provide an updated assessment of the effectiveness of the 25-year rule. It is the first and the most cost

  13. Performance of Duplex Communication between a Leo Satellite and Terrestrial Location Using a Geo Constellation

    NASA Technical Reports Server (NTRS)

    Robinson, Daryl C.; Konangi, Vijay K.; Wallett, Thomas M.

    1998-01-01

    A network comprised of a terrestrial site, a constellation of three GEO satellites and a LEO satellite is modeled and simulated. Continuous communication between the terrestrial site and the LEO satellite is facilitated by the GEO satellites. The LEO satellite has the orbital characteristics of the International Space Station. Communication in the network is based on TCP/IP over ATM, with the ABR service category providing the QoS, at OC-3 data rate. The OSPF protocol is used for routing. We simulate FTP file transfers, with the terrestrial site serving as the client and the LEO satellite being the server. The performance characteristics are presented.

  14. Advances in LO2 Propellant Conditioning

    NASA Technical Reports Server (NTRS)

    Mehta, Gopal; Orth, Michael; Stone, William; Perry, Gretchen; Holt, Kimberly; Suter, John

    1994-01-01

    This paper describes the cryogenic testing and analysis that has recently been completed as part of a multi-year effort to develop a new, more robust and operable LO2 propellant conditioning system. Phase 1 of the program consisted of feasibility demonstrations ot four novel propellant conditioning concepts. A no-bleed, passive propellant conditioning option was shown for the first time to successfully provide desired propellant inlet conditions. The benefits of passive conditioning are reduced operations costs, decreased hardware costs, enhanced operability and increased reliability on future expendable launch vehicles In Phase 2 of the test program, effects of major design parameters were studied and design correlation for future vehicle design were developed. Simultaneously, analytical models were developed and validated. Over 100 tests were conducted with a full-scale feedline using LN2 as the test fluid. A circulation pump provided a range of pressure and flow conditions. The test results showed that the passive propellant conditioning system is insensitive to variations in many of the parameters. The test program provides the validation necessary to incorporate the passive conditioning system into the baseline of future vehicles. Modeling of these systems using computational fluid dynamics seems highly promising.

  15. Impact of GPS tracking data of LEO satellites on global GPS solutions

    NASA Astrophysics Data System (ADS)

    Rothacher, M.; Svehla, D.

    Already at present quite a few Low Earth Orbiting (LEO) satellites (SAC-C, CHAMP, JASON-1, GRACE-1 and GRACE-2) are equipped with one or more GPS receivers for precise orbit determination or other applications (atmospheric sounding, gravity field recovery, . . . ). This trend will continue in the near future (e.g., with the GOCE and COSMIC missions) and we will soon have an entire "constellation" of LEO satellites tracked by GPS at our disposal. In this contribution we want to study the impact of LEO GPS measurements (from a single LEO satellite or from a LEO constellation) on global GPS solutions, where GPS satellite orbits and clocks, Earth rotation parameters (ERPs), station coordinates and troposphere zenith delays are determined simultaneously using the data of the global network of the International GPS Service (IGS). In order to assess the impact of the LEO GPS data on global IGS results, we have to perform a combined analysis of the space-borne and the ground-based GPS data. Such a combination may benefit on one hand from the differences between a ground station and a LEO, e.g., (1) the different tracking geometry (coverage of isolated geographical areas by LEOs, rapidly changing geometry, . . . ), (2) that LEOs connect all ground stations within 1-2 hours, (3) that baselines between LEO and ground stations may be longer than station-station baselines, (4) that no tropospheric delays have to be estimated for LEOs, and (5) that LEOs orbit the Earth within the ionosphere and may therefore contribute to global ionosphere models. On the other hand we have to deal with difficult aspects of precise orbit determination for the LEOs: only if we succeed to obtain very accurate dynamic or reduced-dynamic orbits for the LEOs, we will have a chance at all to improve the global GPS results. We present first results concerning the influence of LEO data on GPS orbits, ERPs, site coordinates, and troposphere zenith delays using both, variance-covariance analyses based on

  16. LEDsats: LEO CubeSats with LEDs for Optical Tracking

    NASA Astrophysics Data System (ADS)

    Seitzer, P.; Cutler, J.; Piergentili, F.; Santoni, F.; Arena, L.; Cardona, T.; Cowardin, H.; Lee, C.; Sharma, S.

    2016-09-01

    We describe a project to launch 1U CubeSats equipped with Light Emitting Diodes (LEDs) into Low Earth Orbit (LEO) for optical tracking with ground-based telescopes. Active illumination on the satellites increases tremendously the number of passes where the LEO satellite is visible when the ground-based telescope is in darkness. The restriction that the satellite is in direct Sun is removed, and so tracking can take place all night long rather than just in twilight. The inspiration for this project came from the Japanese CubeSat FITSAT-1 that carried red and green high-powered LED arrays, and was clearly visible from the ground with small telescopes. There are two goals: 1) increase the accuracy and precision of LEO orbits by increasing the number and length of passes that satellite is visible, and 2) minimize the confusion between objects in the case of multiple CubeSats being launched at the same time. Technical issues to be discussed include the power level required for detection by small (20 - 40 cm) ground based telescopes, the optimum flash pattern for astrometry against star fields, and the timing of the flash pattern to millisecond or better accuracy and precision. We propose to deploy two such LEDsats simultaneously from the International Space Station: the first to be built at the University of Michigan, and the second to be built at Sapienza University Rome. One experiment is to see how we can distinguish these two CubeSats shortly after deployment solely from optical tracking, and so the CubeSats will have different flash patterns.

  17. LEO effects on candidate solar cell cover materials

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.

    1993-01-01

    In 1984, the LDEF (Long Duration Exposure Facility) was placed in LEO (Low Earth Orbit) for a mission planned to last approximately one year. Due to a number of factors, retrieval was delayed until 1990. An experiment, prepared under the direction of JPL, consisted of a test plate with thirty (30) individual thin silicon solar cell/cover samples. The covers consisted of conventional cerium doped microsheet platelets and potential candidate materials, such as FEP Teflon, silicon RTV's, glass resins, polyimides, and a silicone-polyimide copolymer encapsulant. The effects of the LDEF mission environment (micrometeorite/debris impacts, atomic oxygen, UV, and particulate radiation) on the samples are discussed.

  18. LEO effects on conventional and unconventional solar cell cover materials

    NASA Technical Reports Server (NTRS)

    Stella, Paul M.

    1991-01-01

    In 1984, the LDEF (Long Duration Exposure Facility) was placed in LEO (low earth orbit) for a mission planned to last approximately one year. The effects of the LDEF mission environment (micrometeorite/debris impacts, atomic, atomic oxygen, UV, and particulate radiation) on the samples are described. The relative importance of these interactions is highly dependent on orbital altitude. There is no evidence that the impacts with the test samples (including solar cells) caused any electrical degradation. Evidence from a number of LDEF experiments suggests that the majority of the impacts observed on this experiment were of space debris, rather than micrometeorite origin.

  19. Haemangiosarcoma in a captive Asiatic lion (Panthera leo persica)

    PubMed Central

    Vercammen, F.; Brandt, J.; Brantegem, L. Van; Bosseler, L.; Ducatelle, R.

    2015-01-01

    A 2.7-year-old male captive Asiatic lion (Panthera leo persica) died unexpectedly without preceding symptoms. Gross necropsy revealed liver and lung tumours, which proved to be haemangiosarcomas by histopathology. Some of the liver tumours were ruptured, leading to massive intra-abdominal haemorrhage and death. Haemangiosarcomas are rare in domestic and exotic felids, occurring in skin, thoracic-abdominal cavity and bones. Although these tumours mainly appear to be occurring in older cats, they are sometimes observed in younger animals, as in the present case. This is the first description of haemangiosarcoma in a young Asiatic lion. PMID:26623366

  20. Carbon deposition characteristics of LO2/HC propellants

    NASA Technical Reports Server (NTRS)

    Hernandez, Rosemary; Mercer, Steve D.

    1987-01-01

    The generation and deposition of carbon have been studied using subscale hardware with LO2/RP-1, LO2/propane, and LO2/methane at low mixture ratio conditions. The deposition of carbon on the turbine simulator tubes was evaluated at mixture ratios of 0.20 to 0.60, and at chamber pressures from 720 to 1650 psia. The carbon-deposition rate is a strong function of mixture ratio and a weak function of chamber pressure. There is a mixture ratio that will minimize deposition for LO2/RP-1; a threshold mixture ratio for LO2/propane; and no deposition for LO2/methane at any mixture ratio tested. The turbine drive operating limits were defined for each fuel tested.

  1. Telemetry Tracking & Control (TT&C) - First TDRSS, then Commercial GEO & Big LEO and Now Through LEO

    NASA Technical Reports Server (NTRS)

    Morgan, Dwayne R.; Streich, Ron G.; Bull, Barton; Grant, Chuck; Power, Edward I. (Technical Monitor)

    2001-01-01

    The advent of low earth orbit (LEO) commercial communication satellites provides an opportunity to dramatically reduce Telemetry, Tracking and Control (TT&C) costs of launch vehicles, Unpiloted Aerial Vehicles (UAVs), Research Balloons and spacecraft by reducing or eliminating ground infrastructure. Personnel from the Goddard Space Flight Center's Wallops Flight Facility (GSFC\\WFF) have successfully used commercial Geostationary Earth Orbit (GEO) and Big LEO communications satellites for Long Duration Balloon Flight TT&C. The Flight Modem is a GSFC\\WFF Advanced Range Technology initiative (ARTI) designed to streamline TT&C capability in the user community of these scientific data gathering platforms at low cost. Making use of existing LEO satellites and adapting and ruggedized commercially available components; two-way, over the horizon communications may be established with these vehicles at great savings due to reduced infrastructure. Initially planned as a means for permitting GPS data for tracking and recovery of sounding rocket and balloon payloads, expectations are that the bandwidth can soon be expanded to allow more comprehensive data transfer. The system architecture which integrates antennas, GPS receiver, commercial satellite packet data modem and a single board computer with custom software is described and technical challenges are discussed along with the plan for their resolution. A three-phase testing and development plan is outlined and the current results are reported. Results and status of ongoing flight tests on aircraft and sounding rockets are reported. Future applications on these platforms and the potential for satellite support are discussed along with an analysis of cost effectiveness of this method vs. other tracking and data transmission schemes.

  2. Chemical Abundances in the Stellar Populations of the Leo I and Leo II dSph Galaxies

    NASA Astrophysics Data System (ADS)

    Bosler, T. L.; Smecker-Hane, T. A.; Stetson, P. B.

    2002-05-01

    Our goal is to map the chemical abundance distribution of the stellar populations of the Leo I and Leo II dwarf spheroidal (dSph) galaxies to constrain the physical processes that regulate their evolution. The dSphs are particularly interesting galaxies because their star formation histories (SFHs) appear to be much more complicated than theory would predict for such low mass, low luminosity, low surface-brightness galaxies. Color-magnitude diagrams (CMDs) of these dSphs have shown that they formed stars over many Gyr. In order to understand the true spread in stellar ages and chemical abundances we need more precise abundance indicators than can be inferred from CMD analysis: abundances based upon the broad-band colors of red giants are subject to large systematic errors because of limitations in convection theory, and poorly determined color--effective temperature relations produce sizable uncertainties in the derived shapes of theoretical red giant branches. Therefore we are measuring the abundance distribution of the Leo I and Leo II dSphs from spectroscopy of individual red giant stars using the Ca II absorption lines in the near infrared (8498, 8542, and 8662 Å). Our observations are made on the Keck I 10-meter Telescope using the Low Resolution Imaging Spectrometer. One night of successful observations yielded spectra of approximately 40 stars in each dSph from which abundances with random uncertainties of ≈ 0.1 dex will be derived. Calibration of the Ca II strengths to [Fe/H] has been done by Rutledge, et al. (1997, PASP, 109, 907) using Galactic globular clusters. We are also deriving a new calibration for [Ca/H]. This new calibration will remove the dependence on SFH built into the Rutledge, et al. calibration, i.e., the assumptions of a unique age for the system and a Galactic [Ca/Fe]--[Fe/H] relationship. Financial support for this project was provided by NSF grant AST-0070985 to TSH, and an ARCS Foundation fellowship to TB.

  3. Modeling of LEO orbital debris populations for ORDEM2008

    NASA Astrophysics Data System (ADS)

    Xu, Y.-L.; Horstman, M.; Krisko, P. H.; Liou, J.-C.; Matney, M.; Stansbery, E. G.; Stokely, C. L.; Whitlock, D.

    2009-03-01

    The NASA Orbital Debris Engineering Model, ORDEM2000, is in the process of being updated to a new version: ORDEM2008. The data-driven ORDEM covers a spectrum of object size from 10 μm to greater than 1 m, and ranging from LEO (low Earth orbit) to GEO (geosynchronous orbit) altitude regimes. ORDEM2008 centimeter-sized populations are statistically derived from Haystack and HAX (the Haystack Auxiliary) radar data, while micron-sized populations are estimated from shuttle impact records. Each of the model populations consists of a large number of orbits with specified orbital elements, the number of objects on each orbit (with corresponding uncertainty), and the size, type, and material assignment for each object. This paper describes the general methodology and procedure commonly used in the statistical inference of the ORDEM2008 LEO debris populations. Major steps in the population derivations include data analysis, reference-population construction, definition of model parameters in terms of reference populations, linking model parameters with data, seeking best estimates for the model parameters, uncertainty analysis, and assessment of the outcomes. To demonstrate the population-derivation process and to validate the Bayesian statistical model applied in the population derivations throughout, this paper uses illustrative examples for the special cases of large-size (>1 m, >32 cm, and >10 cm) populations that are tracked by SSN (the Space Surveillance Network) and also monitored by Haystack and HAX radars operating in a staring mode.

  4. An active debris removal parametric study for LEO environment remediation

    NASA Astrophysics Data System (ADS)

    Liou, J.-C.

    2011-06-01

    Recent analyses on the instability of the orbital debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have reignited interest in using active debris removal (ADR) to remediate the environment. There are, however, monumental technical, resource, operational, legal, and political challenges in making economically viable ADR a reality. Before a consensus on the need for ADR can be reached, a careful analysis of its effectiveness must be conducted. The goal is to demonstrate the need and feasibility of using ADR to better preserve the future environment and to explore different operational options to maximize the benefit-to-cost ratio. This paper describes a new sensitivity study on using ADR to stabilize the future LEO debris environment. The NASA long-term orbital debris evolutionary model, LEGEND, is used to quantify the effects of several key parameters, including target selection criteria/constraints and the starting epoch of ADR implementation. Additional analyses on potential ADR targets among the existing satellites and the benefits of collision avoidance maneuvers are also included.

  5. Beller Lecture: The Roots of Leo Szilard and his Interdisciplinarity

    NASA Astrophysics Data System (ADS)

    Marx, George

    1998-04-01

    A Central European among the whites was said about Leo Szilard who originated from a polycultural family. In the early 20th century he grew up in Hungary, at the crossroads of history, where political regimes, national borders, ideological doctrines, ``final truths'' changed in a dizzying cavalcade. Instead of conservative dogmatism this social environment required critical thinking in order to survive. World War I was the school of Theodore von Kármán, John von Neumann, Eugene P. Wigner and Leo Szilard; each of them learned trespassing political and disciplinary boundaries without inhibition. Their sensitivity for trends had been utilized by the United States when war efforts and high tech required orientation under new horizons. Szilard's interest ranged from statistical physics through information theory to biological evolution, from life phenomena through hot atoms to nuclear strategy. His intellectual adventures might look crazy jumps for specialists. But now, looking back to the political and technological history of the 20th century one can see than it was a consequent progress of a future-sensitive mind.

  6. MEMS Reaction Control and Maneuvering for Picosat Beyond LEO

    NASA Technical Reports Server (NTRS)

    Alexeenko, Alina

    2016-01-01

    The MEMS Reaction Control and Maneuvering for Picosat Beyond LEO project will further develop a multi-functional small satellite technology for low-power attitude control, or orientation, of picosatellites beyond low Earth orbit (LEO). The Film-Evaporation MEMS Tunable Array (FEMTA) concept initially developed in 2013, is a thermal valving system which utilizes capillary forces in a microchannel to offset internal pressures in a bulk fluid. The local vapor pressure is increased by resistive film heating until it exceeds meniscus strength in a nozzle which induces vacuum boiling and provides a stagnation pressure equal to vapor pressure at that point which is used for propulsion. Interplanetary CubeSats can utilize FEMTA for high slew rate attitude corrections in addition to desaturating reaction wheels. The FEMTA in cooling mode can be used for thermal control during high-power communication events, which are likely to accompany the attitude correction. Current small satellite propulsion options are limited to orbit correction whereas picosatellites are lacking attitude control thrusters. The available attitude control systems are either quickly saturated reaction wheels or movable high drag surfaces with long response times.

  7. Radiation environment at LEO orbits: MC simulation and experimental data.

    NASA Astrophysics Data System (ADS)

    Zanini, Alba; Borla, Oscar; Damasso, Mario; Falzetta, Giuseppe

    The evaluations of the different components of the radiation environment in spacecraft, both in LEO orbits and in deep space is of great importance because the biological effect on humans and the risk for instrumentation strongly depends on the kind of radiation (high or low LET). That is important especially in view of long term manned or unmanned space missions, (mission to Mars, solar system exploration). The study of space radiation field is extremely complex and not completely solved till today. Given the complexity of the radiation field, an accurate dose evaluation should be considered an indispensable part of any space mission. Two simulation codes (MCNPX and GEANT4) have been used to assess the secondary radiation inside FO-TON M3 satellite and ISS. The energy spectra of primary radiation at LEO orbits have been modelled by using various tools (SPENVIS, OMERE, CREME96) considering separately Van Allen protons, the GCR protons and the GCR alpha particles. This data are used as input for the two MC codes and transported inside the spacecraft. The results of two calculation meth-ods have been compared. Moreover some experimental results previously obtained on FOTON M3 satellite by using TLD, Bubble dosimeter and LIULIN detector are considered to check the performances of the two codes. Finally the same experimental device are at present collecting data on the ISS (ASI experiment BIOKIS -nDOSE) and at the end of the mission the results will be compared with the calculation.

  8. An autonomous orbit determination method for MEO and LEO satellite

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Wang, Jin; Yu, Guobin; Zhong, Jie; Lin, Ling

    2014-09-01

    A reliable and secure navigation system and assured autonomous capability of satellite are in high demand in case of emergencies in space. This paper introduces a novel autonomous orbit determination method for Middle-Earth-Orbit and Low-Earth-Orbit (MEO and LEO) satellite by observing space objects whose orbits are known. Generally, the geodetic satellites, such as LAGEOS and ETALONS, can be selected as the space objects here. The precision CCD camera on tracking gimbal can make a series of photos of the objects and surrounding stars when MEO and LEO satellite encounters the space objects. Then the information processor processes images and attains sightings and angular observations of space objects. Several clusters of such angular observations are incorporated into a batch least squares filter to obtain an orbit determination solution. This paper describes basic principle and builds integrated mathematical model. The accuracy of this method is analyzed by means of computer simulation. Then a simulant experiment system is built, and the experimental results demonstrate the feasibility and effectiveness of this method. The experimental results show that this method can attain the accuracy of 150 meters with angular observations of 1 arcsecond system error.

  9. Space Station Element Commonality between LEO and Lunar Infrastructures

    NASA Astrophysics Data System (ADS)

    Hempsell, M.

    Previous work has considered the use of common space station modules launched by the Skylon reusable launch system to construct a large in-orbit infrastructure composed of many small space stations. This previous work assumed this infrastruc- ture extended out to geostationary and lunar locations but without detailed consideration of the implications of operations beyond Low Earth Orbit (LEO). This paper considers the implications of the extension of the approach to the geostationary and lunar environments. These environments impose both different requirements and constraints on the station modules. It is shown, through feasibility concept designs, that these new requirements can be easily incorporated in the core modules so that they can also be used both in LEO and in CIS-lunar space without any significant impact on their effectiveness, although all the requirements do need to be included at the start of the module development. It is also argued that the inclusion of lunar infrastructure requirements into the common modules completely scopes the additional requirements for operation in geostationary orbit. The concept is also extended to lunar surface bases and it is concluded while many new elements would be required some use of common modules is possible but may not be the optimum strategy.

  10. Como Lo Hago Yo: Mielomeningocele En Bolivia

    PubMed Central

    Dabdoub, Carlos F.; Dabdoub, Carlos B.; Villavicencio, Ramiro; Quevedo, Germán

    2014-01-01

    Introducción: Las malformaciones del tubo neural (MTN) representan la segunda causa más frecuente de anomalías congénitas, luego de las cardiopatías. En este grupo se destaca el mielomeningocele (MMC) por su mayor incidencia, y por ser la más incapacitante y la más compleja entre todas las demás malformaciones del sistema nervioso c`entral (SNC). En Bolivia, como en muchos países de Sudamérica, los bajos niveles socio-culturales y la debilidad en el sistema sanitario, hacen que su incidencia y su morbilidad, sean mayores que en las naciones más desarrolladas. Material y Métodos: Se realizó un estudio retrospectivo y descriptivo de 70 casos de MMC, atendidos por un equipo multidisciplinario en el Hospital Universitario Japonés (HUJ) de Santa Cruz de la Sierra, entre 2008-2011. De ellos, 60 fueron intervenidos quirúrgicamente. Resultados: Se realizaron controles prenatales sólo en 27 mujeres (38.6%), diagnosticándose una disrafia espinal en apenas dos casos (7.4%). La edad de ingreso del MMC en su mayoría fue después de las 24 horas (65.6%), predominando su localización en la región lumbosacra (64.3%). De ellos, 67.2% eran abiertos, presentando un 32.9% un daño neurológico motor parcial mientras que 47.1% tenían paraplejia por debajo de la lesión. De los 70 casos, tres (4.3%) no fueron intervenidos, por presentar defectos congénitos severos o estado general grave. Las principales complicaciones posoperatorias inmediatas fueron: dehiscencia de sutura y/o infección de la herida (16.6%), fístula de líquido cefalorraquídeo (LCR) (10%) e infección del SNC (11.7%). La mortalidad general y postoperatoria fue de 7.1% y 3.3%, respectivamente. Al mes de vida presentaban hidrocefalia un 80% de los pacientes operados, colocándose una derivación ventriculoperitoneal (DVP) de presión media. De 9 pacientes que tuvieron un acompanamiento de dos o más años, seis presentaron una médula anclada, que fueron intervenidas quirúrgicamente. Conclusi

  11. Charging of space debris in the LEO and GEO regions

    NASA Astrophysics Data System (ADS)

    Sen, Abhijit; Tiwari, Sanat Kumar

    The near exponential rise of space debris at the satellite orbital altitudes (particularly in the low earth orbit (LEO) region) and the risk they pose for space assets is a source of major concern for all nations engaged in space activities. Considerable efforts are therefore being expended into accurate modeling and tracking of these objects and various ideas for the safe removal of these debris are being explored. The debris objects are likely to acquire a large amount of charge since they are typically found in a plasma environment - such as the earth’s ionospheric plasma in the LEO region (100 kms to 1000 kms) and the radiation belts in the geosynchronous orbit (GEO) region. The consequent flow of electron and ion currents on them lead to the accumulation of a large amount of surface charge and the development of a surface potential on these objects. The influence of the plasma environment on the dynamics and charging of the debris is a relatively unexplored area of Space Situational Awareness (SSA) and Space Debris (SD) research and can be potentially important for the accurate prediction of the long-term evolution of debris orbits and their collision probabilities with other space objects. In this paper we will report on the charging of space debris under a variety of orbital conditions in the LEO and GEO regions using both analytic and particle-in-cell (PIC) modeling. The analytic estimates are obtained using refined Orbit Motion Limited (OML) modeling while the simulation studies are carried out using the SPIS code [1]. In the GEO region account is taken of charging due to photoemission processes as well as energetic beam charging. The PIC approach enables us to study charging of irregularly shaped debris objects as well as differential charging on objects that are composed of patches of conducting and insulated regions. The dynamical consequences of the debris charging on their orbital trajectories and rotational characteristics will be discussed. [1] J

  12. THE ARECIBO LEGACY FAST ALFA SURVEY. IX. THE LEO REGION H I CATALOG, GROUP MEMBERSHIP, AND THE H I MASS FUNCTION FOR THE LEO I GROUP

    SciTech Connect

    Stierwalt, Sabrina; Haynes, Martha P.; Giovanelli, Riccardo; Martin, Ann M.; Kent, Brian R.; Saintonge, Amelie; Karachentsev, Igor D.; Karachentseva, Valentina E. E-mail: haynes@astro.cornell.edu E-mail: amartin@astro.cornell.edu E-mail: amelie@physik.uzh.ch E-mail: vkarach@observ.univ.kiev.ua

    2009-08-15

    We present the catalog of H I sources extracted from the ongoing Arecibo Legacy Fast ALFA (ALFALFA) extragalactic H I line survey, found within the sky region bounded by 9{sup h}36{sup m} < {alpha} < 11{sup h}36{sup m} and +08{sup 0} < {delta} < +12{sup 0}. The H I catalog presented here for this 118 deg{sup 2} region is combined with the ones derived from surrounding regions also covered by the ALFALFA survey to examine the large-scale structure in the complex Leo region. Because of the combination of wide sky coverage and superior sensitivity, spatial and spectral resolution, the ALFALFA H I catalog of the Leo region improves significantly on the numbers of low H I mass sources as compared with those found in previous H I surveys. The H I mass function of the Leo I group presented here is dominated by low-mass objects: 45 of the 65 Leo I members have M{sub H{sub l}}<10{sup 8} M-odot, yielding tight constraints on the low-mass slope of the Leo I H I mass function. The best-fit slope is {alpha} {approx_equal} -1.41 + 0.2 - 0.1. A direct comparison between the ALFALFA H I line detections and an optical search of the Leo I region proves the advantage of the ALFALFA strategy in finding low-mass, gas-rich dwarfs. These results suggest the existence of a significant population of low surface brightness, gas-rich, yet still very low H I mass galaxies, and may reflect the same type of morphological segregation as is seen in the Local Group. While the low-mass end slope of the Leo I H I mass function is steeper than that determined for luminosity functions of the group, the slope still falls short of the values predicted by simulations of structure formation in the lambda cold dark matter paradigm.

  13. Results for p-shell nuclei at LO, NLO, and N2LO in chiral EFT

    NASA Astrophysics Data System (ADS)

    Maris, Pieter; Vary, James

    2016-09-01

    We present results for p-shell nuclei using interactions derived from chiral effective field theory up to N2LO. The many-body calculations are performed order-by-order in the chiral expansion. We show the dependence of the ground state energies on the chiral order; we also present excitation energies of narrow excited states and other observables such as magnetic and quadrupole moments of selected ground states. We discuss both the theoretical uncertainties due to the truncation of the chiral expansion, as well as the numerical uncertainties associated with the many-body method. Supported by the US DOE Grants DESC0008485 (SciDAC/NUCLEI) and DE-FG02-87ER40371. Computational resources provided by NERSC, supported under US DOE Contract DE-AC02-05CH11231, and by the ALCF, supported under US DOE Contract DE-AC02-06CH11357.

  14. Geocenter variations derived from a combined processing of LEO- and ground-based GPS observations

    NASA Astrophysics Data System (ADS)

    Männel, Benjamin; Rothacher, Markus

    2017-01-01

    GNSS observations provided by the global tracking network of the International GNSS Service (IGS, Dow et al. in J Geod 83(3):191-198, 2009) play an important role in the realization of a unique terrestrial reference frame that is accurate enough to allow a detailed monitoring of the Earth's system. Combining these ground-based data with GPS observations tracked by high-quality dual-frequency receivers on-board low earth orbiters (LEOs) is a promising way to further improve the realization of the terrestrial reference frame and the estimation of geocenter coordinates, GPS satellite orbits and Earth rotation parameters. To assess the scope of the improvement on the geocenter coordinates, we processed a network of 53 globally distributed and stable IGS stations together with four LEOs (GRACE-A, GRACE-B, OSTM/Jason-2 and GOCE) over a time interval of 3 years (2010-2012). To ensure fully consistent solutions, the zero-difference phase observations of the ground stations and LEOs were processed in a common least-squares adjustment, estimating all the relevant parameters such as GPS and LEO orbits, station coordinates, Earth rotation parameters and geocenter motion. We present the significant impact of the individual LEO and a combination of all four LEOs on the geocenter coordinates. The formal errors are reduced by around 20% due to the inclusion of one LEO into the ground-only solution, while in a solution with four LEOs LEO-specific characteristics are significantly reduced. We compare the derived geocenter coordinates w.r.t. LAGEOS results and external solutions based on GPS and SLR data. We found good agreement in the amplitudes of all components; however, the phases in x- and z-direction do not agree well.

  15. The Sublime Corpse in Gertrudis Gomez de Avellaneda's Women's Journal "Album Cubano de lo Bueno y lo Bello" (1860)

    ERIC Educational Resources Information Center

    LaGreca, Nancy

    2009-01-01

    This article examines Gertrudis Gomez de Avellaneda's choice to include articles depicting the advanced decay of cadavers, which are simultaneously horrible and awesome, in her women's periodical "Album Cubano de lo Bueno y lo Bello". Background on Avellaneda's biography, women's print culture, and theories of the sublime provide a frame for the…

  16. New Results on RZ Leo and CC Scl

    NASA Astrophysics Data System (ADS)

    Szkody, Paula; Mukadam, Anjum S.; Gaensicke, Boris T.; Toloza, Odette; Dai, Zhibin; HST GO12870 Team

    2017-01-01

    Using HST COS ultraviolet spectra in time-tag mode and a long K2 observation, we have determined a spin period for the white in RZ Leo of 220 seconds, thus confirming this cataclysmic variable as a new member of the Intermediate Polar class of systems. The ultraviolet light curve of CC Scl at quiescence created from its COS spectral observations is dominated by its spin period of 195 seconds (that has only been previously observed during one of its outbursts). Spectra formed from the high and low sections of its light curve shows a temperature difference of several thousand degrees.PS and ASM acknowledge support from NASA grant HST-GO13807 and from NSF grant AST-1514737.

  17. Next Generation Grating Spectrometer Sounders for LEO and GEO

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.

    2011-01-01

    AIRS and MODIS are widely used for weather, climate, composition, carbon cycle, cross-calibration, and applications. The community asking for new capability in the 2020 timeframe, capabilities desired: (1) Hyperspectral UV to LWIR, High Spatial ?1km IFOV (2) Maximize Synergies of Solar Reflected and IR. Synergies with OCO-2. We expect more users and applications of next gen LEO IR Sounder than GEO. These include: weather, climate, GHG monitoring, aviation, disaster response. There is a new direction for imagers and sounders: (1) Separate Vis/NIR/SWIR from MWIR/LWIR instruments reduces technology risk and complexity. (2) Expect Costs to be lower than CrIS & VIIRS Some additional ideas to reduce costs include: (1) minimum set of requirements (2) mini-grating spectrometers. supports constellation for higher revisit (3) new technology to reduce instrument size (large format fpa's) (4) hosted payloads

  18. LEO atomic oxygen effects on spacecraft materials: STS-5 results

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F.

    1984-01-01

    Effects of low Earth orbit (LEO) atomic oxygen were measured on a variety of spacecraft materials which obtained exposure on STS-5. Material degradation dependency on temperature was found in one material. Of the five paints flown, only S13GLO was unaffected. Generally, the glossy paints became Lambertian and the diffuse coatings improved. Scanning electron microscope examinations indicated removal of urethane and epoxy paint binder materials. Reaction products were evident on the surfaces of Z302 paint and Mylar. Thin films showed thickness losses ranging from negligible loss in Teflon to considerable loss in Mylar and Kapton. Glossy films such as black Kapton and white Tedlar became diffused. Kevlar 29 rope lost tensile strength and silver solar cell interconnect material oxidized. Oxidation on the backside of an elevated specimen indicated that reflections of oxygen atoms were occurring and that reflecting surfaces, probably Kapton, were not fully accommodating the incident atoms.

  19. Cranial malformations in related white lions (Panthera leo krugeri).

    PubMed

    Scaglione, F E; Schröder, C; Degiorgi, G; Zeira, O; Bollo, E

    2010-11-01

    White lions (Panthera leo krugeri) have never been common in the wild, and at present, the greatest population is kept in zoos where they are bred for biological and biodiversity conservation. During the years 2003 to 2008 in a zoological garden in northern Italy, 19 white lions were born to the same parents, who were in turn paternally consanguineous. Out of the 19 lions, 4 (21%) were stillborn, 13 (69%) died within 1 month, and 1 (5%) was euthanatized after 6 months because of difficulty with prehension of food. Six lions (32%) showed malformations involving the head (jaw, tongue, throat, teeth, and cranial bones). One lion (5%) still alive at 30 months revealed an Arnold-Chiari malformation upon submission for neurological evaluation of postural and gait abnormalities. Paternal consanguinity of the parents, along with inbreeding among white lions in general, could account for the high incidence of congenital malformations of the head in this pride of white lions.

  20. LEGEND, a LEO-to-GEO Environment Debris Model

    NASA Technical Reports Server (NTRS)

    Liou, Jer Chyi; Hall, Doyle T.

    2013-01-01

    LEGEND (LEO-to-GEO Environment Debris model) is a three-dimensional orbital debris evolutionary model that is capable of simulating the historical and future debris populations in the near-Earth environment. The historical component in LEGEND adopts a deterministic approach to mimic the known historical populations. Launched rocket bodies, spacecraft, and mission-related debris (rings, bolts, etc.) are added to the simulated environment. Known historical breakup events are reproduced, and fragments down to 1 mm in size are created. The LEGEND future projection component adopts a Monte Carlo approach and uses an innovative pair-wise collision probability evaluation algorithm to simulate the future breakups and the growth of the debris populations. This algorithm is based on a new "random sampling in time" approach that preserves characteristics of the traditional approach and captures the rapidly changing nature of the orbital debris environment. LEGEND is a Fortran 90-based numerical simulation program. It operates in a UNIX/Linux environment.

  1. Molecular phylogeny of the extinct cave lion Panthera leo spelaea.

    PubMed

    Burger, Joachim; Rosendahl, Wilfried; Loreille, Odile; Hemmer, Helmut; Eriksson, Torsten; Götherström, Anders; Hiller, Jennifer; Collins, Matthew J; Wess, Timothy; Alt, Kurt W

    2004-03-01

    To reconstruct the phylogenetic position of the extinct cave lion (Panthera leo spelaea), we sequenced 1 kb of the mitochondrial cytochrome b gene from two Pleistocene cave lion DNA samples (47 and 32 ky B.P.). Phylogenetic analysis shows that the ancient sequences form a clade that is most closely related to the extant lions from Africa and Asia; at the same time, cave lions appear to be highly distinct from their living relatives. Our data show that these cave lion sequences represent lineages that were isolated from lions in Africa and Asia since their dispersal over Europe about 600 ky B.P., as they are not found among our sample of extant populations. The cave lion lineages presented here went extinct without mitochondrial descendants on other continents. The high sequence divergence in the cytochrome b gene between cave and modern lions is notable.

  2. LEO high voltage solar array arcing response model

    NASA Astrophysics Data System (ADS)

    Metz, Roger N.

    1987-02-01

    A series of mathematical models were developed that describe the electrical behavior of a large solar cell array floating electrically in the low Earth orbit (LEO) space plasma and struck by an arc at a point of negative bias. There are now three models in this series: ARCII, which is a fully analytical, linearized model; ARCIII, which is an extension of ARCIII that includes solar cell inductance as well as load reactance; Nonlinear ARC, which is a numerical model able to treat effects such as non-linearized, i.e., logarithmic solar cell I/V characteristics, conductance switching as a solar cell crosses plasma ground on a voltage excursion and non-ohmic plasma leakage current collection.

  3. LEO high voltage solar array arcing response model

    NASA Technical Reports Server (NTRS)

    Metz, Roger N.

    1987-01-01

    A series of mathematical models were developed that describe the electrical behavior of a large solar cell array floating electrically in the low Earth orbit (LEO) space plasma and struck by an arc at a point of negative bias. There are now three models in this series: ARCII, which is a fully analytical, linearized model; ARCIII, which is an extension of ARCIII that includes solar cell inductance as well as load reactance; Nonlinear ARC, which is a numerical model able to treat effects such as non-linearized, i.e., logarithmic solar cell I/V characteristics, conductance switching as a solar cell crosses plasma ground on a voltage excursion and non-ohmic plasma leakage current collection.

  4. Blood platelet counts, morphology and morphometry in lions, Panthera leo.

    PubMed

    Du Plessis, L

    2009-09-01

    Due to logistical problems in obtaining sufficient blood samples from apparently healthy animals in the wild in order to establish normal haematological reference values, only limited information regarding the blood platelet count and morphology of free-living lions (Panthera leo) is available. This study provides information on platelet counts and describes their morphology with particular reference to size in two normal, healthy and free-ranging lion populations. Blood samples were collected from a total of 16 lions. Platelet counts, determined manually, ranged between 218 and 358 x 10(9)/l. Light microscopy showed mostly activated platelets of various sizes with prominent granules. At the ultrastructural level the platelets revealed typical mammalian platelet morphology. However, morphometric analysis revealed a significant difference (P < 0.001) in platelet size between the two groups of animals. Basic haematological information obtained in this study may be helpful in future comparative studies between animals of the same species as well as in other felids.

  5. Doramectin toxicity in a group of lions (Panthera leo).

    PubMed

    Lobetti, Remo G; Caldwell, Peter

    2012-10-15

    Ten lions (Panthera leo) that were treated with a single injection of doramectin at a dose ranging between 0.2 mg/kg and 0.5 mg/kg showed clinical signs consistent with avermectin toxicity, namely ataxia, hallucinations, and mydriasis. Two subsequently died whereas the other eight lions recovered after 4-5 days with symptomatic therapy. Post-mortem examinations of the two that died showed cyanosis, severe pulmonary oedema, pleural effusion, and pericardial effusion, with histopathology not revealing any abnormalities. In both these lions, doramectin brain and liver tissue concentrations were elevated. Although doramectin is regularly used in wild felids, to date there have been no reports of avermectin toxicity in the literature. This article highlights the potential for doramectin toxicity in this species.

  6. Treatment of malignant lymphoma in an African lion (Panthera leo).

    PubMed

    Harrison, Tara M; Sikarskie, James; Kitchell, Barbara; Rosenstein, Diana S; Flaherty, Heather; Fitzgerald, Scott D; Kiupel, Matti

    2007-06-01

    A 14 yr-old male, vasectomized African lion (Panthera leo) exhibited mild weight loss despite adequate appetite. Splenomegaly was diagnosed on physical examination. On the basis of hematology and clinical pathology, malignant lymphoma with chronic lymphocytic leukemia was diagnosed. Abdominal exploratory surgery and splenectomy were performed. Histologic examination and immunohistochemistry confirmed a small cell peripheral T-cell lymphoma. Initial treatments consisted of doxorubicin and prednisone, with later addition of lomustine. The lion remained in clinical remission at 2 mo, 6 mo, and 12 mo postchemotherapy physical examinations. The lion survived 504 days from initial diagnosis. At necropsy, the only lesions consistent with lymphoma were localized epitheliotrophic infiltrates of small neoplastic T lymphocytes within the nasopharyngeal epithelium and the underlying submucosa observed on microscopic examination.

  7. CLINICOPATHOLOGIC FEATURES OF MAMMARY MASSES IN CAPTIVE LIONS (PANTHERA LEO).

    PubMed

    Sadler, Ryan A; Craig, Linden E; Ramsay, Edward C; Helmick, Kelly; Collins, Darin; Garner, Michael M

    2016-03-01

    A multi-institutional retrospective analysis of 330 pathology accessions from 285 different lions found 15 captive, female African lions (Panthera leo) with confirmed mammary masses. Aside from the presence of a mammary mass, the most common initial clinical sign was inappetence. Histologic diagnoses were predominantly adenocarcinoma (n = 12), though two benign masses (mammary hyperplasia and a mammary cyst) and one squamous cell carcinoma were identified. Nine of 13 malignant tumors had metastasized to lymph nodes or viscera at the time of necropsy. Six lions with adenocarcinoma and two lions with benign mammary masses had received hormonal contraception, though little evidence of mammary lobular hyperplasia was seen in association with the adenocarcinomas. The most common concurrent disease processes found at necropsy were chronic urinary tract disease and other malignancies. These cases demonstrate that mammary malignancies occur in captive lions and frequently metastasize.

  8. Global tracking and inventory of military hardware via LEO satellite: A system approach and likely scenario

    NASA Technical Reports Server (NTRS)

    Bell, David; Estabrook, Polly; Romer, Richard

    1995-01-01

    A system for global inventory control of electronically tagged military hardware is achievable using a LEO satellite constellation. An equipment Tag can communicate directly to the satellite with a power of 5 watts or less at a data rate of 2400 to 50,000 bps. As examples, two proposed commercial LEO systems, IRIDIUM and ORBCOMM, are both capable of providing global coverage but with dramatically different telecom capacities. Investigation of these two LEO systems as applied to the Tag scenario provides insight into satellite design trade-offs, constellation trade-offs and signal dynamics that effect the performance of a satellite-based global inventory control system.

  9. Semianalytic Theory of Motion for LEO Satellites Under Air Drag

    NASA Astrophysics Data System (ADS)

    Bezdek, A.

    The presented semianalytic theory focuses on the longterm evolution of the LEO satellites motion, with the TD/TD88 model of the total density as a key ingredient. Besides, the theory takes into account the main geopotential perturbations, for satellites with low eccentricity and/or inclination, nonsingular elements are used. An interesting feature of the theory is its computational speed (e.g. the 10-year propagation takes 5.5 s on a PC with Intel Celeron 1.7 GHz), while considering major physical conditions that strongly influence the thermospheric density (solar flux, geomagnetic activity, diurnal and seasonal variations, geographic latitude). The online calculation as well as the code are available on the Internet. The theory has been tested against the real world data of several spherical satellites. For the lifetime prediction accuracy estimate of the theory, we used a confidential interval based on the uncertainty in the drag coefficient CD, while taking the measured values of the solar flux and geomagnetic index. The modelled long-term behaviour of the orbital elements is in reasonably good agreement with the data, the computed lifetimes fall within the CD-induced confidential intervals, typical error in the mean lifetime prediction being a few percent. The tests showed that - provided one appropriately models the solar and geomagnetic activity - the theory may be used in the areas where one needs a quick orbital propagator for LEO objects influenced by air drag (mission planning, lifetime prediction, space debris dynamics). As an example, we will show the mission planning and the medium-term prediction of the motion for the MIMOSA satellite.

  10. Telemetry Tracking and Control Through Commercial LEO Satellites

    NASA Technical Reports Server (NTRS)

    Streich, Ronald C.; Morgan, Dwayne R.; Bull, Barton B.; Grant, Charles E.; Powers, Edward I. (Technical Monitor)

    2001-01-01

    Personnel from the Goddard Space Flight Center Wallops Flight Facility (GSFC/WFF in Virginia have successfully tested commercial LEO communications satellites for sounding rocket, balloon and aircraft flight TT&C. The Flight Modern became a GSFC/WFF Advanced Range Technology Initiative (ARTI) in an effort to streamline TT&C capability to the user community at low cost. Ground tests of the Flight Modem verified duplex communications quality of service and measured transmission latencies. These tests were completed last year and results reported in the John Hopkins University (JHU) Applied Physics Laboratory (APL) 4th International Symposium on Reducing Spacecraft Costs for Ground Systems and Operations. The second phase of the Flight Modem baseline test program was a demonstration of the ruggedized version of the WFF Flight Modem flown on a sounding rocket launched it the Swedish rocket range (Esrangc) near Kiruna, Sweden, with results contained in this paper. Aircraft flight tests have been and continue to be conducted. Flights of opportunity are being actively pursued with other centers, ranges and users at universities. The WFF Flight Modem contains a CPS receiver to provide vehicle position for tracking and vehicle recovery. The system architecture, which integrates antennas, CPS receiver, commercial satellite packet data modem and a single board computer with custom software, is described. Small satellite use of the WFF Flight Modem is also being investigated, The Flight Modem provides an independent vehicle position source for Range Safety applications. The LEO communication system contains a coarse position location system, which is compared to GPS ace acy. This comparison allows users, to determine the need for a CPS receiver in addition to the satellite packet data modem for their application.

  11. Archean evolution of the Leo Rise and its Eburnean reworking

    NASA Astrophysics Data System (ADS)

    Thiéblemont, Denis; Goujou, Jean Christian; Egal, Emmanuel; Cocherie, Alain; Delor, Claude; Lafon, Jean Michel; Fanning, C. Mark

    2004-06-01

    Recent geological mapping in southeastern Guinea, supported by zircon dating, has called into question traditional understanding concerning the evolution of the Leo Rise. Gneiss dated at about 3540 Ma appears to constitute the earliest evidence for continental accretion within the Leo Rise. The existence of a Leonian depositional cycle at about 3000 Ma is confirmed, marked by volcanic and sedimentary rocks that can be correlated with the Loko Group in Sierra Leone. The span of ages (3244-3050 Ma) suggests that the Leonian cycle comprises different episodes whose respective chronology is as yet uncertain. Clearly distinct from the Leonian cycle, the Liberian cycle (˜2900-2800 Ma) is represented in Guinea by granite and migmatite (˜2910-2800 Ma), reflecting remobilization of the ancient Archean basement and deformation of the Leonian rocks; no deposition is associated with this cycle. After the Liberian, the Nimba and Simandou successions, containing Liberian detrital zircons, are assigned to the Birimian (˜2200-2000 Ma). Finally, Eburnean tectonism caused intense deformation of the Archean craton, accompanied by high-grade metamorphism and the intrusion of granite and syenite with ages between 2080 and 2020 Ma. The evolution of the Kénéma-Man domain, attributed to the cumulated effect of the Leonian and Liberian cycles, is thus in part Eburnean. We can suppose, therefore, that the NNE-SSW-trending structures attributed to the Liberian in Sierra Leone are, in fact, Eburnean. The Kambui Supergroup, also affected by this tectonism, should thus be assigned to the Birimian rather than the Liberian, which would explain its similarities with the Nimba and Simandou successions.

  12. End-to-end simulation of a K-band LEO-LEO satellite link for estimating water vapor in the low troposphere

    NASA Astrophysics Data System (ADS)

    Facheris, Luca; Cuccoli, Fabrizio; Argenti, Fabrizio

    2004-11-01

    A new differential measurement concept is presented for retrieving the total content of water vapor (IWV, Integrated Water Vapor) along the propagation path between two Low Earth Orbiting (LEO) satellites, while such path is immersing in the atmosphere during a so called set occultation. The new approach, referred to as DSA (Differential Spectral Absorption) method, is based on the simultaneous measurement of the total attenuation at two relatively close frequencies in the K band, and on the estimate of a "spectral sensitivity parameter" that is highly correlated to the IWV content of the LEO-LEO link in the low troposphere. The DSA approach has the potential to overcome all spectrally 'flat' and spectrally correlated phenomena (atmospheric scintillation among these) and provides estimates that can then be usefully integrated with standard radio occultation data products. In the paper we describe the signaling structure chosen for DSA measurements and the transmit-receive system used to simulate an end-to-end transmission during a complete LEO-LEO set occultation. Simulations are based on atmospheric models and on real radiosonde data, which allows us to account for the natural variability of the atmospheric conditions. The effects on the IWV estimates of impairments such as thermal noise at the receiver, atmospheric scintillation, multipath and defocusing are evaluated.

  13. Differential spectral attenuation measurements at microwaves in a LEO-LEO satellites radio occultation geometry: a novel approach for limiting scintillation effects in tropospheric water vapor measurements

    NASA Astrophysics Data System (ADS)

    Facheris, Luca; Martini, Enrica; Cuccoli, Fabrizio; Argenti, Fabrizio

    2004-12-01

    The DSA (Differential Spectral Attenuation) approach, presented in a companion paper in this conference's proceedings, has the potential to provide the total content of water vapor (IWV, Integrated Water Vapor) along the propagation path between two Low Earth Orbiting (LEO) satellites. The interest towards the DSA, based on the ratio of simultaneous measurements of the total attenuation at two relatively close frequencies in the K-Ku bands, was moved by the need for limiting the effects of tropopheric scintillation and by the fact that DSA measurements are highly correlated to the IWV along the LEO-LEO link. However, the impact of tropospheric scintillation in a LEO-LEO radio occultation geometry using frequencies above 10 GHz still has to be thoroughly investigated. In this paper we focus on the analysis of such effects, taking into account the fact that the formulations presented in the literature have to be modified in order to fit the specific problem under consideration. Specifically, an expression is derived for the variances of the amplitude and phase fluctuations of the wave, their spectrum and the correlation between fluctuations at different frequencies. In particular, the latter is extremely useful to evaluate the potential of the DSA approach through simulations whose results are reported in the last part of the paper.

  14. NEW EMPLOYEE ON THE JOB - LEO C FRANCISCUS MISSIONS ANALYSIS BRANCH WORKING ON RECOVERABLE BOOSTERS

    NASA Technical Reports Server (NTRS)

    1963-01-01

    NEW EMPLOYEE ON THE JOB - LEO C FRANCISCUS MISSIONS ANALYSIS BRANCH WORKING ON RECOVERABLE BOOSTERS - PERFORM MISSION ANALYSIS STUDIES - AT PRESENT TIME STUDYING SUBSONIC AND SUPERSONIC COMBUSTION RAM JET ENGINES - ALSO PERFORMING ANALYTICAL STUDIES

  15. An all electronic transportation system from LEO to GEO and beyond

    NASA Technical Reports Server (NTRS)

    Brown, William C.

    1989-01-01

    System description and moon mission interface; LEO to GEO flight times; technology readiness and modular construction; system capacity and costs; and reduction of propellant mass are outlined. This presentation is represented by viewgraph only.

  16. Celebrating a centennial-Leo Szilárd (1898-1964)

    NASA Astrophysics Data System (ADS)

    Stinner, Arthur

    1998-04-01

    In the long list of gifted Hungarian scientists and mathematicians active in the first half of this century, the name of Leo Szilárd rises to the top. This year we celebrate the centennial of his birth.

  17. Seismic amplitude anomalies associated with thick First Leo sandstone lenses, eastern Powder River basin, Wyoming.

    USGS Publications Warehouse

    Balch, A.H.; Lee, M.W.; Miller, J.J.; Ryder, R.T.

    1981-01-01

    Several new discoveries of oil production in the Leo sandstone, an economic unit in the Pennsylvanian middle member of the Minnelusa formation, eastern Powder River basin, Wyoming-Nebraska-South Dakota, have renewed exploration interest in this area. Vertical seismic profiles (VSP) and model studies suggested that a measurable seismic amplitude anomaly is frequently associated with the thick First Leo sandstone lenses. To test this concept, a surface reflection seismic profile was run between two wells about 12 miles apart. The First Leo was present and productive in one well and thin and barren in the other. The surface profile shows the predicted amplitude anomaly at the well where a thick lens is known to exist. Two other First Leo amplitude anomalies also appear on the surface seismic profile between the two wells, which may indicate the presence of additional lenses.-Authors

  18. A DEEPER LOOK AT LEO IV: STAR FORMATION HISTORY AND EXTENDED STRUCTURE

    SciTech Connect

    Sand, David J.; Seth, Anil; Olszewski, Edward W.; Zaritsky, Dennis; Willman, Beth; Kallivayalil, Nitya

    2010-07-20

    We present MMT/Megacam imaging of the Leo IV dwarf galaxy in order to investigate its structure and star formation history, and to search for signs of association with the recently discovered Leo V satellite. Based on parameterized fits, we find that Leo IV is round, with {epsilon} < 0.23 (at the 68% confidence limit) and a half-light radius of r{sub h} {approx_equal} 130 pc. Additionally, we perform a thorough search for extended structures in the plane of the sky and along the line of sight. We derive our surface brightness detection limit by implanting fake structures into our catalog with stellar populations identical to that of Leo IV. We show that we are sensitive to stream-like structures with surface brightness {mu}{sub r} {approx}< 29.6 mag arcsec{sup -2}, and at this limit we find no stellar bridge between Leo IV (out to a radius of {approx}0.5 kpc) and the recently discovered, nearby satellite Leo V. Using the color-magnitude fitting package StarFISH, we determine that Leo IV is consistent with a single age ({approx}14 Gyr), single metallicity ([Fe/H] {approx} -2.3) stellar population, although we cannot rule out a significant spread in these values. We derive a luminosity of M{sub V} = -5.5 {+-} 0.3. Studying both the spatial distribution and frequency of Leo IV's 'blue plume' stars reveals evidence for a young ({approx}2 Gyr) stellar population which makes up {approx}2% of its stellar mass. This sprinkling of star formation, only detectable in this deep study, highlights the need for further imaging of the new Milky Way satellites along with theoretical work on the expected, detailed properties of these possible 'reionization fossils'.

  19. A Deeper Look at Leo IV: Star Formation History and Extended Structure

    NASA Astrophysics Data System (ADS)

    Sand, David J.; Seth, Anil; Olszewski, Edward W.; Willman, Beth; Zaritsky, Dennis; Kallivayalil, Nitya

    2010-07-01

    We present MMT/Megacam imaging of the Leo IV dwarf galaxy in order to investigate its structure and star formation history, and to search for signs of association with the recently discovered Leo V satellite. Based on parameterized fits, we find that Leo IV is round, with epsilon < 0.23 (at the 68% confidence limit) and a half-light radius of rh ~= 130 pc. Additionally, we perform a thorough search for extended structures in the plane of the sky and along the line of sight. We derive our surface brightness detection limit by implanting fake structures into our catalog with stellar populations identical to that of Leo IV. We show that we are sensitive to stream-like structures with surface brightness μ r <~ 29.6 mag arcsec-2, and at this limit we find no stellar bridge between Leo IV (out to a radius of ~0.5 kpc) and the recently discovered, nearby satellite Leo V. Using the color-magnitude fitting package StarFISH, we determine that Leo IV is consistent with a single age (~14 Gyr), single metallicity ([Fe/H] ~ -2.3) stellar population, although we cannot rule out a significant spread in these values. We derive a luminosity of MV = -5.5 ± 0.3. Studying both the spatial distribution and frequency of Leo IV's "blue plume" stars reveals evidence for a young (~2 Gyr) stellar population which makes up ~2% of its stellar mass. This sprinkling of star formation, only detectable in this deep study, highlights the need for further imaging of the new Milky Way satellites along with theoretical work on the expected, detailed properties of these possible "reionization fossils." Observations reported here were obtained at the MMT observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

  20. LoFASM's FPGA-based Digital Acquisition System

    NASA Astrophysics Data System (ADS)

    Dartez, Louis P.; Jenet, F.; Creighton, T. D.; Ford, A. J.; Hicks, B.; Hinojosa, J.; Kassim, N. E.; Price, R. H.; Stovall, K.; Ray, P. S.; Taylor, G. B.

    2014-01-01

    The Low Frequency All Sky Monitor (LoFASM) is a distributed array of dipole antennas that are sensitive to radio frequencies from 10 to 88 MHz. LoFASM consists of antennas and front end electronics that were originally developed for the Long Wavelength Array (LWA) by the U.S. Naval Research Lab, the University of New Mexico, Virginia Tech, and the Jet Propulsion Laboratory. LoFASM, funded by the U.S. Department of Defense, will initially consist of 4 stations, each consisting of 12 dual-polarization dipole antenna stands. The primary science goals of LoFASM will be the detection and study of low-frequency radio transients, a high priority science goal as deemed by the National Research Council's decadal survey. The data acquisition system for the LoFASM antenna array will be using Field Programmable Gate Array (FPGA) technology to implement a real time full Stokes spectrometer and data recorder. This poster presents an overview of the current design and digital architecture of a single station of the LoFASM array as well as the status of the entire project.

  1. LEO1 is regulated by PRL-3 and mediates its oncogenic properties in acute myelogenous leukemia.

    PubMed

    Chong, Phyllis S Y; Zhou, Jianbiao; Cheong, Lip-Lee; Liu, Shaw-Cheng; Qian, Jingru; Guo, Tiannan; Sze, Siu Kwan; Zeng, Qi; Chng, Wee Joo

    2014-06-01

    PRL-3, an oncogenic dual-specificity phosphatase, is overexpressed in 50% of acute myelogenous leukemia (AML) and associated with poor survival. We found that stable expression of PRL-3 confers cytokine independence and growth advantage of AML cells. However, how PRL-3 mediates these functions in AML is not known. To comprehensively screen for PRL3-regulated proteins in AML, we performed SILAC-based quantitative proteomics analysis and discovered 398 significantly perturbed proteins after PRL-3 overexpression. We show that Leo1, a component of RNA polymerase II-associated factor (PAF) complex, is a novel and important mediator of PRL-3 oncogenic activities in AML. We described a novel mechanism where elevated PRL-3 protein increases JMJD2C histone demethylase occupancy on Leo1 promoter, thereby reducing the H3K9me3 repressive signals and promoting Leo1 gene expression. Furthermore, PRL-3 and Leo1 levels were positively associated in AML patient samples (N=24; P<0.01). On the other hand, inhibition of Leo1 reverses PRL-3 oncogenic phenotypes in AML. Loss of Leo1 leads to destabilization of the PAF complex and downregulation of SOX2 and SOX4, potent oncogenes in myeloid transformation. In conclusion, we identify an important and novel mechanism by which PRL-3 mediates its oncogenic function in AML.

  2. Depositional environments of middle Minnelusa Leo (Middle and Upper Pennsylvanian), Wyoming, South Dakota, and Nebraska

    SciTech Connect

    Tromp, P.L.

    1983-08-01

    The informal middle member of the Minnelusa Formation, commonly known as Leo, consists of a spectrum of sediments including sandstone, dolomite, anhydrite, bedded chert, limestone, and radioactive carbonaceous shale. Deposition within the upper Paleozoic alliance basin of the present day tri-state area of South Dakota, Wyoming, and Nebraska occurred in sabkha, tidal flat, and shallow subtidal environments. Major and minor cycles of eustatic sea level changes are manifest by the Leo section. Early Desmoinesian (lowermost Leo) sediments are open marine, upper subtidal limestone interbedded with restricted marine upper subtidal dolomite, anhydrite, and radioactive organic-rich dolomite. During the upper Desmoinesian and lower Missourian, most of the Alliance basin was a restricted carbonate tidal flat. Throughout the remainder of the Pennsylvanian, the prevalent environment was a restricted coastal to inland sabkha with episodic inundations intercalating intertidal dolomite and lagoonal black shale with the sabkha sediments. Prolonged periods of exposure allowed migration of eolian bypass with only isolated patches of dunes being trapped by rare topographic relief. Criteria suggesting windblown deposition of the majority of Leo sandstone include deflationary lag surfaces, low-amplitude ripples, subcritically climbing translatent cross-stratification, and sand-flow toes. Isolated eolian sandstones provide excellent stratigraphic traps for hydrocarbons generated in the organic-rich shales. The current flurry of Leo drilling that began in 1978, has affirmed the inherent potential of this play. Definition of paleodepositional trends and seismic recognition of isolated dunes are the keys to Leo exploration success.

  3. The Many Worlds of Leo Szilard: Physicist, Peacemaker, Provocateur

    NASA Astrophysics Data System (ADS)

    Lanouette, William

    2014-03-01

    Best known for being the first to conceive and patent the nuclear chain reaction in the 1930s, Leo Szilard should also be remembered for other insights in both physics and biology, and for historical initiatives to control the A-bomb he helped create. In physics, Szilard applied entropy to data in a seminal 1929 paper that laid the basis for ``information theory.'' Szilard co-designed an electromagnetic refrigerator pump with Einstein in the 1920s, in 1939 he co-designed the first nuclear reactor with Enrico Fermi, and he later thought up and named the nuclear ``breeder'' reactor. Biologist Francois Jacob called Szilard an ``intellectual bumblebee'' for the many novel ideas he shared, including one that earned Jacob and others the Nobel Prize. James D. Watson said that for intellectual stimulation he liked being around Szilard because ``Leo got excited about something before it was true.'' A political activist, Szilard proposed and drafted the 1939 letter Einstein sent to President Franklin Roosevelt that warned of German A-bomb work and led to the Manhattan Project - where Szilard was ``Chief Physicist.'' Yet Szilard then worked tirelessly to curb nuclear weapons, organizing a scientists' petition to President Truman and lobbying Congress for civilian control of the atom. Szilard loved dreaming up new institutions. He helped to create the Pugwash Conferences on Science and World Affairs, and founded the Council for a Livable World - the first political action committee for arms control. In biology, Szilard proposed the European Molecular Biology Organization modeled on CERN, and helped create the Salk Institute for Biological Studies, where he was one of the first fellows. Shy, witty, and eccentric, Szilard wrote a political satire in 1960 that predicted when the US-Soviet nuclear arms race would end in the late 1980s. Another satire, ``My Trial as a War Criminal'' about scientists' responsibilities for weapons of mass destruction, is credited with prompting

  4. NiH2 Battery Reconditioning for LEO Applications

    NASA Technical Reports Server (NTRS)

    Armantrout, J. D.; Hafen, D. P.

    1997-01-01

    This paper summarizes reasons for and benefits of reconditioning nickel-hydrogen (NiH2) batteries used for Low Earth Orbit (LEO) applications. NiH2 battery cells do not have the classic discharge voltage problems more commonly associated with nickel-cadmium (NiCd) cells. This is due, in part, to use of hydrogen electrodes in place of cadmium electrodes. The nickel electrode, however, does have a similar discharge voltage signature for both cell designs. This can have an impact on LEO applications where peak loads at higher relative depths of discharge can impact operations. Periodic reconditioning provides information which can be used for analyzing long term performance trends to predict usable capacity to a specified voltage level. The reconditioning process described herein involves discharging NiH2 batteries at C/20 rates or less, to an average cell voltage of 1.0 volts or less. Recharge is performed at nominal C/5 rates to specified voltage/temperature (V/T) charge levels selected to restore required capacity with minimal overcharge. Reconditioning is a process of restoring reserve capacity lost on cycling, which is commonly called the memory effect in NiCd cells. This effect is characterized by decreases in the discharge voltage curve with operational life and cycling. The end effect of reconditioning NiH2 cells may be hidden in the versatility, of that design over the NiCd cell design and its associated negative electrode fading problem. The process of deep discharge at lower rates by way of reconditioning tends to redistribute electrolyte and water in the NiH2 cell electrode stack, while improving utilization and charge efficiency. NiH2 battery reconditioning effects on life are considered beneficial and may, in fact. extend life based on NiCd experience. In any case, usable capacity data obtained from reconditioning is required for performance evaluation and trend analysis. Characterization and life tests have provided the historical data base used to

  5. THE SPACE MOTION OF LEO I: HUBBLE SPACE TELESCOPE PROPER MOTION AND IMPLIED ORBIT

    SciTech Connect

    Sohn, Sangmo Tony; Van der Marel, Roeland P.; Besla, Gurtina; Boylan-Kolchin, Michael; Bullock, James S.; Majewski, Steven R.

    2013-05-10

    We present the first absolute proper motion measurement of Leo I, based on two epochs of Hubble Space Telescope ACS/WFC images separated by {approx}5 years in time. The average shift of Leo I stars with respect to {approx}100 background galaxies implies a proper motion of ({mu}{sub W}, {mu}{sub N}) = (0.1140 {+-} 0.0295, -0.1256 {+-} 0.0293) mas yr{sup -1}. The implied Galactocentric velocity vector, corrected for the reflex motion of the Sun, has radial and tangential components V{sub rad} = 167.9 {+-} 2.8 km s{sup -1} and V{sub tan} = 101.0 {+-} 34.4 km s{sup -1}, respectively. We study the detailed orbital history of Leo I by solving its equations of motion backward in time for a range of plausible mass models for the Milky Way (MW) and its surrounding galaxies. Leo I entered the MW virial radius 2.33 {+-} 0.21 Gyr ago, most likely on its first infall. It had a pericentric approach 1.05 {+-} 0.09 Gyr ago at a Galactocentric distance of 91 {+-} 36 kpc. We associate these timescales with characteristic timescales in Leo I's star formation history, which shows an enhanced star formation activity {approx}2 Gyr ago and quenching {approx}1 Gyr ago. There is no indication from our calculations that other galaxies have significantly influenced Leo I's orbit, although there is a small probability that it may have interacted with either Ursa Minor or Leo II within the last {approx}1 Gyr. For most plausible MW masses, the observed velocity implies that Leo I is bound to the MW. However, it may not be appropriate to include it in models of the MW satellite population that assume dynamical equilibrium, given its recent infall. Solution of the complete (non-radial) timing equations for the Leo I orbit implies an MW mass M{sub MW,vir} = 3.15{sub -1.36}{sup +1.58} x 10{sup 12} M{sub Sun }, with the large uncertainty dominated by cosmic scatter. In a companion paper, we compare the new observations to the properties of Leo I subhalo analogs extracted from cosmological

  6. Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells. An update

    NASA Technical Reports Server (NTRS)

    Smithrick, John J.; Hall, Stephen W.

    1991-01-01

    An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

  7. Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells - An update

    NASA Technical Reports Server (NTRS)

    Smithrick, John J.; Hall, Stephen W.

    1991-01-01

    An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent potassium hydroxide (KOH) electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel nickel-hydrogen cells is reported. The cycle life of boiler plate cells containing 26 percent KOH electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH.

  8. A SEARCH FOR DUST EMISSION IN THE LEO INTERGALACTIC CLOUD

    SciTech Connect

    Bot, Caroline; Helou, George; Puget, Jeremie; Latter, William B.; Schneider, Stephen; Terzian, Yervant

    2009-08-15

    We present a search for infrared dust emission associated with the Leo cloud, a large intergalactic cloud in the M96 group. Mid-infrared and far-infrared images were obtained with the InfraRed Array Camera and the Multiband Imaging Photometer for Spitzer on the Spitzer Space Telescope. Our analysis of these maps is done at each wavelength relative to the H I spatial distribution. We observe a probable detection at 8 {mu}m and a marginal detection at 24 {mu}m associated with the highest H I column densities in the cloud. At 70 and 160 {mu}m, upper limits on the dust emission are deduced. The level of the detection is low so that the possibility of a fortuitous cirrus clump or of an overdensity of extragalactic sources along the line of sight cannot be excluded. If this detection is confirmed, the quantities of dust inferred imply a dust-to-gas ratio in the intergalactic cloud up to a few times solar but no less than 1/20 solar. A confirmed detection would therefore exclude the possibility that the intergalactic cloud has a primordial origin. Instead, this large intergalactic cloud could therefore have been formed through interactions between galaxies in the group.

  9. Arcing in LEO - Does the Whole Array Discharge?

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.; Vayner, Boris V.; Galofaro, Joel T.; Hillard, G. Barry

    2005-01-01

    The conventional wisdom about solar array arcing in LEO is that only the parts the solar array that are swept over by the arc-generated plasma front are discharged in the initial arc. This limits the amount of energy that can be discharged. Recent work done at the NASA Glenn Research Center has shown that this idea is mistaken. In fact, the capacitance of the entire solar array may be discharged, which for large arrays leads to very large and possibly debilitating arcs, even if no sustained arc occurs. We present the laboratory work that conclusively demonstrates this fact by using a grounded plate that prevents the arc-plasma front from reaching certain array strings. Finally, we discuss the dependence of arc strength and arc pulse width on the capacitance that is discharged, and provide a physical mechanism for discharge of the entire array, even when parts of the array are not accessible to the arc-plasma front. Mitigation techniques are also presented.

  10. A Metapopulation Approach to African Lion (Panthera leo) Conservation

    PubMed Central

    Dolrenry, Stephanie; Stenglein, Jennifer; Hazzah, Leela; Lutz, R. Scott; Frank, Laurence

    2014-01-01

    Due to anthropogenic pressures, African lion (Panthera leo) populations in Kenya and Tanzania are increasingly limited to fragmented populations. Lions living on isolated habitat patches exist in a matrix of less-preferred habitat. A framework of habitat patches within a less-suitable matrix describes a metapopulation. Metapopulation analysis can provide insight into the dynamics of each population patch in reference to the system as a whole, and these analyses often guide conservation planning. We present the first metapopulation analysis of African lions. We use a spatially-realistic model to investigate how sex-biased dispersal abilities of lions affect patch occupancy and also examine whether human densities surrounding the remaining lion populations affect the metapopulation as a whole. Our results indicate that male lion dispersal ability strongly contributes to population connectivity while the lesser dispersal ability of females could be a limiting factor. When populations go extinct, recolonization will not occur if distances between patches exceed female dispersal ability or if females are not able to survive moving across the matrix. This has profound implications for the overall metapopulation; the female models showed an intrinsic extinction rate from five-fold to a hundred-fold higher than the male models. Patch isolation is a consideration for even the largest lion populations. As lion populations continue to decline and with local extinctions occurring, female dispersal ability and the proximity to the nearest lion population are serious considerations for the recolonization of individual populations and for broader conservation efforts. PMID:24505385

  11. Arcing in LEO: Does the Whole Array Discharge?

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.; Vayner, Boris V.; Galofaro, Joel T.; Hillard, G. Barry

    2005-01-01

    The conventional wisdom about solar array arcing in LEO is that only the parts of the solar array that are swept over by the arc-generated plasma front are discharged in the initial arc. This limits the amount of energy that can be discharged. Recent work done at the NASA Glenn Research Center has shown that this idea is mistaken. In fact, the capacitance of the entire solar array may be discharged, which for large arrays leads to very large and possibly debilitating arcs, even if no sustained arc occurs. We present the laboratory work that conclusively demonstrates this fact by using a grounded plate that prevents the arc-plasma front from reaching certain array strings. Finally, we discuss the dependence of arc strength and arc pulse width on the capacitance that is discharged, and provide a physical mechanism for discharge of the entire array, even when parts of the array are not accessible to the arc-plasma front. Mitigation techniques are also presented.

  12. A metapopulation approach to African lion (Panthera leo) conservation.

    PubMed

    Dolrenry, Stephanie; Stenglein, Jennifer; Hazzah, Leela; Lutz, R Scott; Frank, Laurence

    2014-01-01

    Due to anthropogenic pressures, African lion (Panthera leo) populations in Kenya and Tanzania are increasingly limited to fragmented populations. Lions living on isolated habitat patches exist in a matrix of less-preferred habitat. A framework of habitat patches within a less-suitable matrix describes a metapopulation. Metapopulation analysis can provide insight into the dynamics of each population patch in reference to the system as a whole, and these analyses often guide conservation planning. We present the first metapopulation analysis of African lions. We use a spatially-realistic model to investigate how sex-biased dispersal abilities of lions affect patch occupancy and also examine whether human densities surrounding the remaining lion populations affect the metapopulation as a whole. Our results indicate that male lion dispersal ability strongly contributes to population connectivity while the lesser dispersal ability of females could be a limiting factor. When populations go extinct, recolonization will not occur if distances between patches exceed female dispersal ability or if females are not able to survive moving across the matrix. This has profound implications for the overall metapopulation; the female models showed an intrinsic extinction rate from five-fold to a hundred-fold higher than the male models. Patch isolation is a consideration for even the largest lion populations. As lion populations continue to decline and with local extinctions occurring, female dispersal ability and the proximity to the nearest lion population are serious considerations for the recolonization of individual populations and for broader conservation efforts.

  13. CBERS Satellites: Resonant Orbital Motions in LEO Region

    NASA Astrophysics Data System (ADS)

    Vilhena de Moraes, Rodolpho; Sampaio, J. C.; da Silva Fernandes, S.; Wnuk, E.

    2013-05-01

    Abstract (2,250 Maximum Characters): The space between the Earth and the Moon has several artificial satellites and space debris in some resonance. Synchronous satellites in circular or elliptical orbits have been studied in literature, including the analysis of resonant orbits characterizing the dynamics of these satellites. In general, some resonant angles associated to the exact resonance are considered in the numerical integration, with the purpose to describe the resonance defined by the commensurability between the mean motion of the object and the Earth’s rotation angular velocity. However, the tesseral harmonics Jlm produce multiple resonances in the exact resonance and in the neighborhood of the exact resonance, and, some disturbances in the orbital motions of objects are not described. In this work, the TLE (Two-Line Elements) of the NORAD (North American Defense) are studied observing the resonant objects orbiting the Earth in LEO (Low Earth Orbit) region. Analyzing the cataloged objects, the CBERS satellites are studied observing resonance effects which compose your orbits. The time behavior of the orbital elements, resonant period and resonant angles are considered and possible regular and irregular motions are analyzed. About 60 space debris produced by the CBERS-1 satellite mission are studied analyzing the reentry of these objects in the Planet.

  14. Space-based visible observation strategy for beyond-LEO objects based on an equatorial LEO satellite with multi-sensors

    NASA Astrophysics Data System (ADS)

    Hu, Yun-peng; Huang, Jian-yu; Chen, Lei

    2017-04-01

    Many space-based visible observation strategies based on Low Earth Orbit (LEO) satellites for observing Geosynchronous Orbit (GEO) objects were proposed previously. However, there were few studies about other beyond-LEO objects (Geostationary Transfer Orbit (GTO) objects, Medium Earth Orbit (MEO) objects, and Molniya objects). In this paper, a space-based visible observation strategy is proposed for observing GEO objects, GTO objects, MEO objects (especially global navigation satellites), and Molniya objects simultaneously to get more orbital data, using an earth-oriented equatorial LEO satellite with three sensors. This work is focused on the pointing geometry. Brightness of observed objects and sensitivity of sensors are assumed under the relative ideal conditions. First, the distribution characteristics of these beyond-LEO objects are discussed. And in order to observe global navigation satellites efficiently, joint regions formed by the track superposition of two adjacent orbits in a constellation are proposed. To offset the influence of the earth shadow and constraint of sun-target-observer angle, two sensors pointing inside of the equatorial plane are used to observe GEO and GTO objects. The installation angle of the third sensor is optimized to obtain a relative high coverage rate for observing global navigation satellites and Molniya objects based on joint regions. Finally, the coverage rate, the number of observations, and observation duration under different sensors with different field of views (FOVs) are compared and analyzed respectively.

  15. Study of LEO-SAT microwave link for broad-band mobile satellite communication system

    NASA Technical Reports Server (NTRS)

    Fujise, Masayuki; Chujo, Wataru; Chiba, Isamu; Furuhama, Yoji; Kawabata, Kazuaki; Konishi, Yoshihiko

    1993-01-01

    In the field of mobile satellite communications, a system based on low-earth-orbit satellites (LEO-SAT's) such as the Iridium system has been proposed. The LEO-SAT system is able to offer mobile telecommunication services in high-latitude areas. Rain degradation, fading and shadowing are also expected to be decreased when the system is operated at a high elevation angle. Furthermore, the propagation delay generated in the LEO-SAT system is less pronounced than that in the geostationary orbit satellite (GEO-SAT) system and, in voice services, the effect of the delay is almost negligible. We proposed a concept of a broad-band mobile satellite communication system with LEO-SAT's and Optical ISL. In that system, a fixed L-band (1.6/1.5 GHz) multibeam is used to offer narrow band service to the mobile terminals in the entire area covered by a LEO-SAT and steerable Ka-band (30/20 GHz) spot beams are used for the wide band service. In this paper, we present results of a study of LEO-SAT microwave link between a satellite and a mobile terminal for a broad-band mobile satellite communication system. First, the results of link budget calculations are presented and the antennas mounted on satellites are shown. For a future mobile antenna technology, we also show digital beamforming (DBF) techniques. DBF, together with modulation and/or demodulation, is becoming a key technique for mobile antennas with advanced functions such as antenna pattern calibration, correction, and radio interference suppression. In this paper, efficient DBF techniques for transmitting and receiving are presented. Furthermore, an adaptive array antenna system suitable for this LEO-SAT is presented.

  16. THE STAR FORMATION HISTORY OF LEO T FROM HUBBLE SPACE TELESCOPE IMAGING

    SciTech Connect

    Weisz, Daniel R.; Dalcanton, Julianne J.; Gilbert, Karoline M.; Williams, Benjamin F.; Zucker, Daniel B.; Dolphin, Andrew E.; Martin, Nicolas F.; De Jong, Jelte T. A.; Holtzman, Jon A.; Bell, Eric F.; Belokurov, Vasily; Evans, N. Wyn

    2012-04-01

    We present the star formation history (SFH) of the faintest known star-forming galaxy, Leo T, based on deep imaging taken with the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2). The HST/WFPC2 color-magnitude diagram (CMD) of Leo T is exquisitely deep, extending {approx}2 mag below the oldest main-sequence turnoff, permitting excellent constraints on star formation at all ages. We use a maximum likelihood CMD fitting technique to measure the SFH of Leo T assuming three different sets of stellar evolution models: Padova (solar-scaled metallicity) and BaSTI (both solar-scaled and {alpha}-enhanced metallicities). The resulting SFHs are remarkably consistent at all ages, indicating that our derived SFH is robust to the choice of stellar evolution model. From the lifetime SFH of Leo T, we find that 50% of the total stellar mass formed prior to z {approx} 1 (7.6 Gyr ago). Subsequent to this epoch, the SFH of Leo T is roughly constant until the most recent {approx}25 Myr, where the SFH shows an abrupt drop. This decrease could be due to a cessation of star formation or stellar initial mass function sampling effects, but we are unable to distinguish between the two scenarios. Overall, our measured SFH is consistent with previously derived SFHs of Leo T. However, the HST-based solution provides improved age resolution and reduced uncertainties at all epochs. The SFH, baryonic gas fraction, and location of Leo T are unlike any of the other recently discovered faint dwarf galaxies in the Local Group, and instead bear strong resemblance to gas-rich dwarf galaxies (irregular or transition), suggesting that gas-rich dwarf galaxies may share common modes of star formation over a large range of stellar mass ({approx}10{sup 5}-10{sup 9} M{sub Sun }).

  17. An Abel transform for deriving line-of-sight wind profiles from LEO-LEO infrared laser occultation measurements

    NASA Astrophysics Data System (ADS)

    Syndergaard, S.; Kirchengast, G.

    2016-03-01

    We have developed a formula for the retrieval of the line-of-sight (l.o.s.) wind speed from future low Earth orbit (LEO) satellite-to-satellite infrared laser occultation measurements. The formula involves an Abelian integral transform akin to the Abel transform widely used for deriving refractive index from bending angle in Global Navigation Satellite System radio occultation measurements. Besides the Abelian integral transform, the formula is derived from a truncated series expansion of the volume absorption coefficient as a function of frequency and includes a simple absorption-line-asymmetry correction term. A first-order formulation (referred to as the standard formula) is complemented by higher-order terms that can be used for high-accuracy computations. Under the assumptions of spherical symmetry and perfect knowledge of spectroscopy, the residual l.o.s. wind error from using the standard formula rather than the high-accuracy formula is assessed to be small compared to that anticipated from measurement errors in a real experiment. Applying the new formula just in standard form to future infrared laser transmission profiles would therefore enable the retrieval of l.o.s. stratospheric wind profiles with an accuracy limited mainly by measurement errors, residual spectroscopic errors, and deviations from spherical symmetry.

  18. The Oxygen and Nitrogen Abundance of Leo A and GR 8

    NASA Astrophysics Data System (ADS)

    van Zee, L.; Skillman, E. D.; Haynes, M. P.

    1999-05-01

    Gas phase abundances are one of the best measures of the intrinsic metallicity of low mass galaxies. We recently obtained low resolution long slit optical spectra of several HII regions in Leo A and GR 8 with the Palomar 5m telescope. Previous studies of the resolved stellar population of Leo A indicated that the stars have metallicities approximately 2% of solar (Tolstoy et al. 1998). Preliminary analysis of the HII region spectra, and that of a planetary nebula, indicates that the gas phase oxygen abundance of Leo A is approximately 3% of solar. This confirms the result of Skillman et al. (1989), who also derived an oxygen abundance for Leo A from a planetary nebula. Similarly, for GR 8 we find a mean oxygen abundance of 5% of solar. For all the HII regions, the derived log(N/O) is -1.5 +/- 0.1, as has been found for other low metallicity systems. These new observations of multiple HII regions in Leo A and GR 8 confirm that metals in low mass galaxies are well mixed.

  19. An Assessment of the Current LEO Debris Environment and the Need for Active Debris Removal

    NASA Technical Reports Server (NTRS)

    Liou, Jer-Chyi

    2010-01-01

    The anti-satellite test on the Fengun-1 C weather satellite in early 2007 and the collision between Iridium 33 and Cosmos 2251 in 2009 dramatically altered the landscape of the human-made orbital debris environment in the low Earth orbit (LEO). The two events generated approximately 5500 fragments large enough to be tracked by the U.S. Space Surveillance Network. Those fragments account for more than 60% increase to the debris population in LEO. However, even before the ASAT test, model analyses already indicated that the debris population (for those larger than 10 cm) in LEO had reached a point where the population would continue to increase, due to collisions among existing objects, even without any future launches. The conclusion implies that as satellites continue to be launched and unexpected breakup events continue to occur, commonly-adopted mitigation measures will not be able to stop the collision-driven population growth. To remediate the debris environment in LEO, active debris removal must be considered. This presentation will provide an updated assessment of the debris environment after the Iridium 33/Cosmos 2251 collision, an analysis of several future environment projections based on different scenarios, and a projection of collision activities in LEO in the near future. The need to use active debris removal to stabilize future debris environment will be demonstrated and the effectiveness of various active debris removal strategies will be quantified.

  20. Leo P: A very low-mass, extremely metal-poor, star-forming galaxy

    NASA Astrophysics Data System (ADS)

    McQuinn, Kristen B.; Leo P Team

    2017-01-01

    Leo P is a low-luminosity dwarf galaxy just outside the Local Group with properties that make it an ideal probe of galaxy evolution at the faint-end of the luminosity function. Using combined data from 2 Hubble Space Telescope (HST) observing campaigns, the Very Large Array, the Spitzer Space telescope, as well as ground based data, we have constructed a robust evolutionary picture of Leo P. Leo P is one the most metal-poor, gas-rich galaxies ever discovered, has a stellar mass of a 5x105 Msun, comparable gas mass, and a single HII region. The star formation history reconstructed from the resolved stellar populations in Leo P shows it is unquenched, despite its very low mass. Based on the star formation history and metallicity measurements, the galaxy has lost 95% of its oxygen produced via nucleosynthesis, presumably to outflows. The neutral gas in the galaxy shows signs of rotation, although the velocity dispersion is comparable to the rotation velocity. Thus, Leo P bridges the gap between more massive dwarf irregular and less massive dwarf spheroidals on the baryonic Tully-Fisher relation. Furthermore, the galaxy hosts several, extremely dusty AGB candidates which will be probed with new HST and Spitzer observations. If confirmed as AGB stars, these may be our best local proxies for studying chemically unevolved star formation and subsequent dust production in metallicity environments comparable to the early universe.

  1. The effect of solar forcing induced atmospheric perturbations on LEO satellites' nominal aerodynamic drag

    NASA Astrophysics Data System (ADS)

    Nwankwo, Victor U. J.; Chakrabarti, Sandip Kumar; Weigel, Robert

    2016-07-01

    Atmospheric drag is the strongest force perturbing the motion of satellites in low Earth orbits LEO, and could cause re-entry of satellites, difficulty in identifying and tracking of the satellites and other space objects, manuvering and prediction of lifetime and re-entry. Solar activities influence the temperature, density and composition of the upper atmosphere. These effects thus strongly depend on the phase of a solar cycle. The frequency of intense flares and storms increase during solar maximum. Heating up of the atmosphere causes its expansion eventually leading to accelerated drag of orbiting satellites, especially those in LEO. In this paper, we present the model of the atmospheric drag effect on the trajectory of hypothetical LEO satellites of different ballistic coefficients. We investigate long-term trend of atmospheric drag on LEO satellites due to solar forcing induced atmospheric perturbations and heating at different phases of the solar cycle, and during interval of strong geomagnetic disturbances or storms. We show the dependence of orbital decay on severity of both the solar cycle and phase, and the extent of geomagnetic perturbations. The result of the model compares well with the observed decay profile of existing LEO satellites and provides a better understanding of the issue of the orbital decay. Our result may also be useful for selection of launch window of satellites for an extended lifetime in the orbit.

  2. Low-Earth-Orbiter resource allocation and capacity planning for the DSN using LEO4CAST

    NASA Technical Reports Server (NTRS)

    Fox, G.; Borden, C.

    1994-01-01

    The Deep Space Network provides tracking and communication services for a number of U.S. and international low-Earth-orbiting (LEO) and near-Earth missions. This service is supplied by the 26-m subnet (located at each of the DSN complexes), the 9-m and the 34-m Antenna Research System antennas at Goldstone, and the 11-m antennas (following the orbital VLBI mission). An increasing number of LEO missions are planned for DSN support, which will result in increasingly complex ground resource allocation and mission support trades. To support TDA decision making on mission support and cost-effective ground system evolution for this 26-m subnet, LEO4CAST has been developed. LEO4CAST is a tool that uses statistical approaches to provide useful information for long-term ground system capacity planning and near-term resource allocation (prior to detailed time-of-day scheduling). LEO4CAST is currently beta-test software and is being exercised by both the Office of Telecommunications and Data Acquisition (TDA) and the JPL Systems Division.

  3. BabeLO--An Extensible Converter of Programming Exercises Formats

    ERIC Educational Resources Information Center

    Queiros, R.; Leal, J. P.

    2013-01-01

    In the last two decades, there was a proliferation of programming exercise formats that hinders interoperability in automatic assessment. In the lack of a widely accepted standard, a pragmatic solution is to convert content among the existing formats. BabeLO is a programming exercise converter providing services to a network of heterogeneous…

  4. Complete Genome Sequence of Burkholderia cepacia Strain LO6

    PubMed Central

    Belcaid, Mahdi; Kang, Yun; Tuanyok, Apichai

    2015-01-01

    Burkholderia cepacia strain LO6 is a betaproteobacterium that was isolated from a cystic fibrosis patient. Here we report the 6.4 Mb draft genome sequence assembled into 2 contigs. This genome sequence will aid the transcriptomic profiling of this bacterium and help us to better understand the mechanisms specific to pulmonary infections. PMID:26067955

  5. Complete Genome Sequence of Burkholderia cepacia Strain LO6.

    PubMed

    Belcaid, Mahdi; Kang, Yun; Tuanyok, Apichai; Hoang, Tung T

    2015-06-11

    Burkholderia cepacia strain LO6 is a betaproteobacterium that was isolated from a cystic fibrosis patient. Here we report the 6.4 Mb draft genome sequence assembled into 2 contigs. This genome sequence will aid the transcriptomic profiling of this bacterium and help us to better understand the mechanisms specific to pulmonary infections.

  6. Low energy neutron deuteron scattering to N3LO

    NASA Astrophysics Data System (ADS)

    Margaryan, Arman; Vanasse, Jared; Springer, Roxanne

    2015-10-01

    We calculate the next-to-next-to-next-to-leading order (N3LO) nd scattering amplitude in the framework of nonrelativistic pionless effective field theory (EFTπ/). This theory is only valid when the typical momentum exchange in the scattering is smaller then the mass of the pion. The power counting parameter for EFTπ/ is the ratio Q/Λπ /, where Q is the typical momentum exchange in the scattering and Λπ / is the EFTπ/ breakdown scale, Λπ / LO. At N3LO new 2-body forces appear, which introduce four new EFTπ/ coefficients. These coefficients are fixed by the 3PJ and 1P1 phase shifts of NN scattering. We find that these terms have an important impact. The results of this calculation at N3LO will be important for understanding spin polarization observables in nd scattering, in particular the longstanding Ay puzzle. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics, under Award Number DE-FG02-05ER41368.

  7. GEO vs. LEO Space Telecommunication Systems Commercial Set Up, Finance &Economics

    NASA Astrophysics Data System (ADS)

    Kreisel, Joerg

    2002-01-01

    Space-based commercial telecommunication systems - especially in GEO - still represent the big volume segment in commercial space and probably will do so for a while. Although such end-to-end systems both in GEO and LEO are using satellites, ground stations, and service centers, etc., their commercial genesis differs significantly. Based on existing and planned space telecommunication businesses, this paper deals with prime characteristics of commercial GEO and LEO systems and their differences. In a tutorial way the stages of development of both LEO- and GEO-type business ventures are presented. The entire commercial development path is covered (concept, business plan, financing, partnership, growth, etc.). Focus is to understand what drives space telecommunication business and what it takes to start such new commercial space ventures. The perspective given is also based on the author's longstanding background in space commercialization and experiences made as a venture capitalist.

  8. Handover aspects for a Low Earth Orbit (LEO) CDMA Land Mobile Satellite (LMS) system

    NASA Astrophysics Data System (ADS)

    Carter, P.; Beach, M. A.

    This paper addresses the problem of handoff in a land mobile satellite (LMS) system between adjacent satellites in a low earth orbit (LEO) constellation. In particular, emphasis is placed on the application of soft handoff in a direct sequence code division multiple access (DS-CDMA) LMS system. Soft handoff is explained in terms of terrestrial macroscopic diversity, in which signals transmitted via several independent fading paths are combined to enhance the link quality. This concept is then reconsidered in the context of a LEO LMS system. A two-state Markov channel model is used to simulate the effects of shadowing on the communications path from the mobile to each satellite during handoff. The results of the channel simulation form a platform for discussion regarding soft handoff, highlighting the potential merits of the scheme when applied in a LEO LMS environment.

  9. Optical Observation of LEO Debris Caused by Feng Yun 1C

    NASA Astrophysics Data System (ADS)

    Kurosaki, Hirohisa; Yanagisawa, Toshifumi; Nakajima, Atsushi

    Many pieces of space debris are in low earth orbit (LEO), and may be a serious problem in the near future. They are very hazardous to spacecraft such as the ISS, in which humans stay for long periods. In January 2007, China performed an experimental destruction of the meteorological satellite FengYun-1C in low earth orbit using a ballistic missile. Optical instruments for space debris observation were installed on Mt. Nyukasa in Nagano Prefecture by JAXA, and the resulting low earth orbit debris was observed with the small telescope there. We have developed an image-processing technique, the line-detection method, to extract such effects as the streaks created by meteors, LEO satellites, and LEO debris. We succeeded in detecting the trajectories of specified FengYun-1C debris whose TLE were known. In this paper, the detection and observation of low earth orbit debris are discussed.

  10. Handover aspects for a Low Earth Orbit (LEO) CDMA Land Mobile Satellite (LMS) system

    NASA Technical Reports Server (NTRS)

    Carter, P.; Beach, M. A.

    1993-01-01

    This paper addresses the problem of handoff in a land mobile satellite (LMS) system between adjacent satellites in a low earth orbit (LEO) constellation. In particular, emphasis is placed on the application of soft handoff in a direct sequence code division multiple access (DS-CDMA) LMS system. Soft handoff is explained in terms of terrestrial macroscopic diversity, in which signals transmitted via several independent fading paths are combined to enhance the link quality. This concept is then reconsidered in the context of a LEO LMS system. A two-state Markov channel model is used to simulate the effects of shadowing on the communications path from the mobile to each satellite during handoff. The results of the channel simulation form a platform for discussion regarding soft handoff, highlighting the potential merits of the scheme when applied in a LEO LMS environment.

  11. Materials selection for long life in LEO: A critical evaluation of atomic oxygen testing with thermal atom systems

    NASA Technical Reports Server (NTRS)

    Koontz, S. L.; Kuminecz, J.; Leger, L.; Nordine, P.

    1988-01-01

    The use of thermal atom test methods as a materials selection and screening technique for low-Earth orbit (LEO) spacecraft is critically evaluated. The chemistry and physics of thermal atom environments are compared with the LEO environment. The relative reactivities of a number of materials determined to be in thermal atom environments are compared to those observed in LEO and in high quality LEO simulations. Reaction efficiencies measured in a new type of thermal atom apparatus are one-hundredth to one-thousandth those observed in LEO, and many materials showing nearly identical reactivities in LEO show relative reactivities differing by as much as a factor of 8 in thermal atom systems. A simple phenomenological kinetic model for the reaction of oxygen atoms with organic materials can be used to explain the differences in reactivity in different environments. Certain specific thermal test environments can be used as reliable materials screening tools. Using thermal atom methods to predict material lifetime in LEO requires direct calibration of the method against LEO data or high quality simulation data for each material.

  12. Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight battery cells

    NASA Technical Reports Server (NTRS)

    Smithrick, John J.; Hall, Stephen W.

    1990-01-01

    A breakthrough in low earth orbit (LEO) cycle life of individual pressure vessel (IPV) nickel hydrogen battery cells was reported. The cycle life of boiler plate cells containing 26 percent potassium hydroxide (KOH) electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH. The effect of KOH concentration on cycle life was studied. The cycle regime was a stressful accelerated LEO, which consisted of a 27.5 min charge followed by a 17.5 min charge (2 x normal rate). The depth of discharge (DOD) was 80 percent. The cell temperature was maintained at 23 C. The next step is to validate these results using flight hardware and a real time LEO test. NASA Lewis has a contract with the Naval Weapons Support Center (NWSC), Crane, Indiana, to validate the boiler plate test results. Six 48 A-hr Hughes recirculation design IPV nickel-hydrogen flight battery cells are being evaluated. Three of the cells contain 26 percent KOH (test cells) and three contain 31 percent KOH (control cells). They are undergoing real time LEO cycle life testing. The cycle regime is a 90-min LEO orbit consisting of a 54-min charge followed by a 36-min discharge. The depth-of-discharge is 80 percent. The cell temperature is maintained at 10 C. The cells were cycled for over 8000 cycles in the continuing test. There were no failures for the cells containing 26 percent KOH. There was two failures, however, for the cells containing 31 percent KOH.

  13. The Space Motion of Leo I: The Mass of the Milky Way's Dark Matter Halo

    NASA Astrophysics Data System (ADS)

    Boylan-Kolchin, Michael; Bullock, James S.; Sohn, Sangmo Tony; Besla, Gurtina; van der Marel, Roeland P.

    2013-05-01

    We combine our Hubble Space Telescope measurement of the proper motion of the Leo I dwarf spheroidal galaxy (presented in a companion paper) with the highest resolution numerical simulations of Galaxy-size dark matter halos in existence to constrain the mass of the Milky Way's dark matter halo (M vir, MW). Despite Leo I's large Galactocentric space velocity (200 km s-1) and distance (261 kpc), we show that it is extremely unlikely to be unbound if Galactic satellites are associated with dark matter substructure, as 99.9% of subhalos in the simulations are bound to their host. The observed position and velocity of Leo I strongly disfavor a low-mass Milky Way: if we assume that Leo I is the least bound of the Milky Way's classical satellites, then we find that M vir, MW > 1012 M ⊙ at 95% confidence for a variety of Bayesian priors on M vir, MW. In lower mass halos, it is vanishingly rare to find subhalos at 261 kpc moving as fast as Leo I. Should an additional classical satellite be found to be less bound than Leo I, this lower limit on M vir, MW would increase by 30%. Imposing a mass-weighted ΛCDM prior, we find a median Milky Way virial mass of M vir, MW = 1.6 × 1012 M ⊙, with a 90% confidence interval of [1.0-2.4] × 1012 M ⊙. We also confirm a strong correlation between subhalo infall time and orbital energy in the simulations and show that proper motions can aid significantly in interpreting the infall times and orbital histories of satellites.

  14. Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight battery cells

    NASA Technical Reports Server (NTRS)

    Smithrick, John J.; Hall, Stephen W.

    1990-01-01

    A breakthrough in the low-earth-orbit (LEO) cycle life of individual pressure vessel (IPV) nickel hydrogen battery cells is reported. The cycle life of boiler plate cells containing 26 percent potassium hydroxide (KOH) electrolyte was about 40,000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH. The effect of KOH concentration on cycle life was studied. The cycle regime was a stressful accelerated LEO, which consisted of a 27.5 min charge followed by a 17.5 min charge (2 x normal rate). The depth of discharge (DOD) was 80 percent. The cell temperature was maintained at 23 C. The next step is to validate these results using flight hardware and real time LEO test. NASA Lewis has a contract with the Naval Weapons Support Center (NWSC), Crane, Indiana to validate the boiler plate test results. Six 48 A-hr Hughes recirculation design IPV nickel-hydrogen flight battery cells are being evaluated. Three of the cells contain 26 percent KOH (test cells) and three contain 31 percent KOH (control cells). They are undergoing real time LEO cycle life testing. The cycle regime is a 90-min LEO orbit consisting of a 54-min charge followed by a 36-min discharge. The depth-of-discharge is 80 percent. The cell temperature is maintained at 10 C. The cells were cycled for over 8000 cycles in the continuing test. There were no failures for the cells containing 26 percent KOH. There were two failures, however, for the cells containing 31 percent KOH.

  15. THE SPACE MOTION OF LEO I: THE MASS OF THE MILKY WAY'S DARK MATTER HALO

    SciTech Connect

    Boylan-Kolchin, Michael; Bullock, James S.; Sohn, Sangmo Tony; Van der Marel, Roeland P.; Besla, Gurtina

    2013-05-10

    We combine our Hubble Space Telescope measurement of the proper motion of the Leo I dwarf spheroidal galaxy (presented in a companion paper) with the highest resolution numerical simulations of Galaxy-size dark matter halos in existence to constrain the mass of the Milky Way's dark matter halo (M{sub vir,MW}). Despite Leo I's large Galactocentric space velocity (200 km s{sup -1}) and distance (261 kpc), we show that it is extremely unlikely to be unbound if Galactic satellites are associated with dark matter substructure, as 99.9% of subhalos in the simulations are bound to their host. The observed position and velocity of Leo I strongly disfavor a low-mass Milky Way: if we assume that Leo I is the least bound of the Milky Way's classical satellites, then we find that M{sub vir,MW} > 10{sup 12} M{sub Sun} at 95% confidence for a variety of Bayesian priors on M{sub vir,MW}. In lower mass halos, it is vanishingly rare to find subhalos at 261 kpc moving as fast as Leo I. Should an additional classical satellite be found to be less bound than Leo I, this lower limit on M{sub vir,MW} would increase by 30%. Imposing a mass-weighted {Lambda}CDM prior, we find a median Milky Way virial mass of M{sub vir,MW} = 1.6 Multiplication-Sign 10{sup 12} M{sub Sun }, with a 90% confidence interval of [1.0-2.4] Multiplication-Sign 10{sup 12} M{sub Sun }. We also confirm a strong correlation between subhalo infall time and orbital energy in the simulations and show that proper motions can aid significantly in interpreting the infall times and orbital histories of satellites.

  16. Dynamical evidence for a strong tidal interaction between the Milky Way and its satellite, Leo V

    NASA Astrophysics Data System (ADS)

    Collins, Michelle L. M.; Tollerud, Erik J.; Sand, David J.; Bonaca, Ana; Willman, Beth; Strader, Jay

    2017-01-01

    We present a chemodynamical analysis of the Leo V dwarf galaxy, based on Keck II DEIMOS spectra of 8 member stars. We find a systemic velocity for the system of < v_rrangle = 170.9^{+ 2.1}_{-1.9} km s^{-1}, and barely resolve a velocity dispersion for the system, with σ _{vr} = 2.3^{+3.2}_{-1.6} km s^{-1}, consistent with previous studies of Leo V. The poorly resolved dispersion means we are unable to adequately constrain the dark matter content of Leo V. We find an average metallicity for the dwarf of [Fe/H]=-2.48 ± 0.21, and measure a significant spread in the iron abundance of its member stars, with -3.1 ≤[Fe/H]≤-1.9 dex, which cleanly identifies Leo V as a dwarf galaxy that has been able to self-enrich its stellar population through extended star formation. Owing to the tentative photometric evidence for tidal substructure around Leo V, we also investigate whether there is any evidence for tidal stripping or shocking of the system within its dynamics. We measure a significant velocity gradient across the system, of dv/dχ = -4.1^{+2.8}_{-2.6} km s^{-1} per arcmin (or dv/dχ = -71.9^{+50.8}_{-45.6} km s^{-1} kpc-1), which points almost directly toward the Galactic centre. We argue that Leo V is likely a dwarf on the brink of dissolution, having just barely survived a past encounter with the centre of the Milky Way.

  17. New U-Pb SHRIMP dating for the Leo Pargil gneiss dome, western Himalaya

    NASA Astrophysics Data System (ADS)

    Leech, M. L.; Sas, R.

    2006-12-01

    The Leo Pargil gneiss dome is comprised of upper amphibolite-facies metasedimentary rocks of the lower Tethyan Himalayan sequence (the Haimantas unit) that are intruded by numerous small granitoid bodies and leucogranite dikes. The dome is exposed in northern India/southwestern Tibet at the confluence of the Sutlej and Spiti rivers west of the Zada basin. The dome is bound by generally N-S trending normal faults; the western boundary is termed the Kaurik-Chango normal fault and has a history of recent seismicity. The Leo Pargil dome differs from other North Himalayan domes in that it exhibits orogen-parallel stretching lineations and a uniform top-to-the-northwest sense-of-shear on its western flank (in contrast to approximately arc-normal stretching lineations and variable sense-of-shear in other North Himalayan domes; the youngest phase of Leo Pargil dome development is related to an orogen-parallel extensional structure similar to that which bounds the Gurla Mandhata dome to the southeast. New U-Pb SHRIMP dating of zircon yields Late Archean to Late Proterozoic ages for Leo Pargil paragneisses (c. 800-900 Ma and rarer 2-3 Ga zircons) and Late Oligocene to Early Miocene ages for granitoid intrusions (c. 27-16 Ma). These Oligocene to Miocene ages for Leo Pargil granitoids may correspond to magmatism associated with the widespread leucogranite bodies exposed througout the Himalaya. The Leo Pargil dome, like other similar Himalayan gneiss domes, may be exposures of a ductile mid-crustal channel.

  18. An Assessment of the January 2007 Chinese ASAT Test on the LEO Environment

    NASA Astrophysics Data System (ADS)

    Talent, D.

    Over the past several decades there has been increasing concern regarding the growth of the orbital debris population in the Low Earth Orbit (LEO) environment. Even under the best of circumstances the debris population may be expected to increase under conditions of ambient use by the space-faring nations of the world. It is easy to see that such a situation will obtain since the operational lifetimes of most on-orbit systems are typically less than a decade, while their orbital lifetimes may be many decades to hundreds of years or more. Historically, very little has been done regarding the removal of defunct orbital systems. Making matters worse, there have been many cases of spontaneous explosion of derelict upper stages on orbit. In such an event, a single large "hazard to navigation" becomes hundreds to thousands of pieces of orbiting shrapnel. As the numbers of debris objects increases, for whatever reason, so does the threat of collision with high-value operational assets. Thus, given the importance of minimizing orbital debris in LEO, it is obvious that any nation conducting anti-satellite (ASAT) tests should do so in a responsible fashion - minimizing the long-term deposition of large numbers of orbital debris objects at operational LEO altitudes. It is the thesis of this paper that the January 2007 ASAT test conducted by the Chinese government was particularly careless in this regard. In support of this statement, Oceanit's LEO environment model, PODEM (patented in 2004), was employed. The Chinese ASAT test was conducted successfully at an altitude of about 850 km producing large numbers of debris objects. Results, based on an approximation to this recent event, utilizing the PODEM model, suggest that meter-size debris pieces may remain in the LEO environment for hundreds of years. By contrast, debris ranging in size from one to several centimeters may be expected to drift down, due to drag, through lower LEO altitudes producing a transient spike in hazard

  19. Magnitude Standardization Procedure for OWL-Net Optical Observations of LEO Satellites

    NASA Astrophysics Data System (ADS)

    Roh, Dong-Goo; Choi, Jin; Jo, Jung Hyun; Yim, Hong-Suh; Park, Sun-Youp; Park, Maru; Choi, Young-Jun; Bae, Young-Ho; Park, Young-Sik; Jang, Hyun-Jung; Cho, Sungki; Kim, Ji-Hye; Park, Jang-Hyun

    2015-12-01

    As a governmentally approved domestic entity for Space Situational Awareness, Korea Astronomy and Space Science Institute (KASI) is developing and operating an optical telescopes system, Optical Wide-field PatroL (OWL) Network. During the test phase of this system, it is necessary to determine the range of brightness of the observable satellites. We have defined standard magnitude for Low Earth Orbit (LEO) satellites to calibrate their luminosity in terms of standard parameters such as distance, phase angle, and angular rate. In this work, we report the optical brightness range of five LEO Satellites using OWL-Net.

  20. DWARF IRREGULAR GALAXY LEO A: SUPRIME-CAM WIDE-FIELD STELLAR PHOTOMETRY

    SciTech Connect

    Stonkutė, Rima; Narbutis, Donatas; Vansevičius, Vladas; Arimoto, Nobuo; Hasegawa, Takashi; Tamura, Naoyuki

    2014-10-01

    We have surveyed a complete extent of Leo A—an apparently isolated gas-rich low-mass dwarf irregular galaxy in the Local Group. The B, V, and I passband CCD images (typical seeing ∼0.''8) were obtained with the Subaru Telescope equipped with the Suprime-Cam mosaic camera. The wide-field (20' × 24') photometry catalog of 38,856 objects (V ∼ 16-26 mag) is presented. This survey is also intended to serve as ''a finding chart'' for future imaging and spectroscopic observation programs of Leo A.

  1. A photometric study of the dwarf spheroidal galaxies Leo IV and Bootes II

    NASA Astrophysics Data System (ADS)

    Cheng, Haw

    A photometric study of the ultra-faint dwarf (UFD) galaxies Leo IV and Bootes II in the V and IC filters is here presented. The age of Leo IV relative to M92 were derived by fitting of Dartmouth isochrones, by a "standard" VHBTO method, and by the V HBTO method of VandenBerg et al. 2013. The age of Bootes II relative to M92 was derived by fitting of Dartmouth isochrones. Leo IV is found to be between 2 to 2.5 Gyr younger than M92 by these three methods. It is found to be predominantly old and metal poor and is well fit by isochrones of [Fe/H] = ---2.46 and [alpha/Fe] = 0.2 and 0.4. An age spread with a plausible value of ˜ 2 Gyr cannot be ruled out. A 10 Gyr old synthetic horizontal branch with [Fe/H] = ---1.70 and [alpha/Fe] of 0.2 is fit to Leo IV's red horizontal branch (RHB). The good fit of this model and its matching isochrone to Leo IV's CMD suggests that the RHB is real and not an observational artifact as proposed by Okamoto et al. 2012. Two RRab Lyraes previously observed by Moretti et al. 2009 were observed in Leo IV. One of the stars, V1, is observed to exhibit the Blazhko effect. No further RR Lyraes were uncovered in Leo IV. Comparison of the horizontal branch's observed V magnitude to the absolute magnitudes of the RR Lyraes yields a distance modulus of (m---M)0 = 21.01 +/- 0.07, in good agreement with previous studies. Leo IV's possible population of blue stragglers is found to show no signs of central concentration, though this study's sample and spatial coverage are too small for any detailed spatial distribution study. Bootes II's CMD is found to be consistent with that of a single age, mono-metallicity system. It is well fit by isochrones of [Fe/H] = ---1.79 and [alpha/Fe] = 0.2 and 0.4. Bootes II is found to be between 0.5 to 1.5 Gyr younger than M92. Distance was left as a free parameter in the fits. Bootes II is found to have distance modulus (m---M)0 lying between 18.02 to 18.15, in good agreement with previous studies. A single RRab Lyrae

  2. Standard for Solar Array Arc-Prevention in LEO - NASA 4005

    NASA Technical Reports Server (NTRS)

    Ferguson, Dale C.

    2006-01-01

    Spacecraft charging in Low Earth Orbit (LEO) is commonly caused by the high voltage (>55 V) solar array power system. Conversely, arcing on the solar arrays is an undesirable consequence of the spacecraft charging. The new NASA Low Earth Orbit Spacecraft Charging Design Standard and Information Handbook (NASA-4005) presents a standard and all the necessary background information to understand how to eliminate solar array arcing on LEO spacecraft in the design stage, before the spacecraft is built, and before costly retrofits are needed.

  3. A new concept for high-cycle-life LEO: Rechargeable MnO2-hydrogen

    NASA Technical Reports Server (NTRS)

    Appleby, A. J.; Dhar, H. P.; Kim, Y. J.; Murphy, O. J.

    1989-01-01

    The nickel-hydrogen secondary battery system, developed in the early 1970s, has become the system of choice for geostationary earth orbit (GEO) applications. However, for low earth orbit (LEO) satellites with long expected lifetimes the nickel positive limits performance. This requires derating of the cell to achieve very long cycle life. A new system, rechargeable MnO2-Hydrogen, which does not require derating, is described here. For LEO applications, it promises to have longer cycle life, high rate capability, a higher effective energy density, and much lower self-discharge behavior than those of the nickel-hydrogen system.

  4. Ever Ready to Go: The Multiple Exiles of Leo Szilard

    NASA Astrophysics Data System (ADS)

    Frank, Tibor

    2005-06-01

    I argue that to understand the life and work of Leo Szilard (1898 1964) we have to understand, first, that he was driven by events to numerous departures, escapes, and exiles, changing his religion, his language, his country of residence, and his scientific disciplines; second, that he was a man haunted by major moral dilemmas throughout his life, burdened by a sincere and grave sense of responsibility for the fate of the world; and third, that he experienced a terrible sense of déjà vu: his excessive sensitivity and constant alertness were products of his experiences as a young student in Budapest in 1919. The mature Szilard in Berlin of 1933, and forever after, was always ready to move. I proceed as follows:After a brief introduction to his family background, youth, and education in Budapest, I discuss the impact of his army service in the Great War and of the tumultous events in Hungary in 1918 1919 on his life and psyche, forcing him to leave Budapest for Berlin in late 1919. He completed his doctoral degree under Max von Laue (1879 1960) at the University of Berlin in 1922 and his Habilitationsschrift in 1925. During the 1920s and early 1930s, he filed a number of patents, several of them jointly with Albert Einstein (1879 1955). He left Berlin in March 1933 for London where he played a leading role in the rescue operations for refugee scientists and scholars from Nazi Germany. He also carried out notable research in nuclear physics in London and Oxford before immigrating to the United States at the end of 1938. He drafted Einstein’s famous letter of August 2, 1939, to President Franklin D. Roosevelt, worked in the Manhattan Project during World War II, initiated a petition to President Harry S. Truman not to use the bomb on Japan, and immediately after the war was a leader in the scientists’ movement that resulted in civilian control of nuclear energy. In 1946 he turned to biology, in which his most significant contribution was to formulate a theory of

  5. Liquid oxygen (LO2) propellant conditioning concept testing

    NASA Technical Reports Server (NTRS)

    Perry, Gretchen L. E.; Orth, Michael S.; Mehta, Gopal K.

    1993-01-01

    Testing of a simplified LO2 propellant conditioning concept for future expendable launch vehicles is discussed. Four different concepts are being investigated: no-bleed, low-bleed, use of a recirculation line, and He bubbling. A full-scale test article, which is a facsimile of a propellant feed duct with an attached section to simulate heat input from an LO2 turbopump, is to be tested at the Cold Flow Facility of the Marshall Space Flight Center West Test Area. Work to date includes: design and fabrication of the test article, design of the test facility and initial fabrication, development of a test matrix and test procedures, initial predictions of test output, and heat leak calibration and heat exchanger tests on the test articles.

  6. Liquid Oxygen (LO2) propellant conditioning concept testing

    NASA Technical Reports Server (NTRS)

    Perry, Gretchen L. E.; Orth, Michael S.; Mehta, Gopal K.

    1993-01-01

    Marshall Space Flight Center (MSFC) and industry contractors have undertaken activities to develop a simplified liquid oxygen (LO2) propellant conditioning concept for future expendable launch vehicles. The objective of these activities is to reduce operations costs and timelines and to improve safety of these vehicles. The approach followed has been to identify novel concepts through system level studies and demonstrate the feasibility of these concepts through small-scale and full-scale testing. Testing will also provide data for design guidelines and validation of analytical models. Four different concepts are being investigated: no-bleed, low-bleed, use of a recirculation line, and helium (He) bubbling. This investigation is being done under a Joint Institutional Research and Development (JIRAD) program currently in effect between MSFC and General Dynamics Space Systems (GDSS). A full-scale test article, which is a facsimile of a propellant feed duct with an attached section to simulate heat input from a LO2 turbopump, will be tested at the Cold Flow Facility at MSFC's West Test Area. Liquid nitrogen (LN2), which has similar properties to LO2, will be used in place of LO2 for safety and budget reasons. Work to date includes design and fabrication of the test article, design of the test facility and initial fabrication, development of a test matrix and test procedures, initial predictions of test output, and heat leak calibration and heat exchanger tests on the test article. The tests for all propellant conditioning concepts will be conducted in the summer of 1993, with the final report completed by October, 1993.

  7. Quadrature mixture LO suppression via DSW DAC noise dither

    DOEpatents

    Dubbert, Dale F.; Dudley, Peter A.

    2007-08-21

    A Quadrature Error Corrected Digital Waveform Synthesizer (QECDWS) employs frequency dependent phase error corrections to, in effect, pre-distort the phase characteristic of the chirp to compensate for the frequency dependent phase nonlinearity of the RF and microwave subsystem. In addition, the QECDWS can employ frequency dependent correction vectors to the quadrature amplitude and phase of the synthesized output. The quadrature corrections cancel the radars' quadrature upconverter (mixer) errors to null the unwanted spectral image. A result is the direct generation of an RF waveform, which has a theoretical chirp bandwidth equal to the QECDWS clock frequency (1 to 1.2 GHz) with the high Spurious Free Dynamic Range (SFDR) necessary for high dynamic range radar systems such as SAR. To correct for the problematic upconverter local oscillator (LO) leakage, precision DC offsets can be applied over the chirped pulse using a pseudo-random noise dither. The present dither technique can effectively produce a quadrature DC bias which has the precision required to adequately suppress the LO leakage. A calibration technique can be employed to calculate both the quadrature correction vectors and the LO-nulling DC offsets using the radar built-in test capability.

  8. The ClearfLo project - Understanding London's meteorology and composition

    NASA Astrophysics Data System (ADS)

    Belcher, Stephen; Bohnenstengel, Sylvia

    2014-05-01

    ClearfLo is a large multi-institutional project funded by the UK Natural Environment Research Council (NERC). ClearfLo established integrated measurements of meteorology, gaseous and particulate composition/loading of London's (UK) urban atmosphere in 2011 and 2012 to understand the processes underlying poor air quality. A new and unique long-term measurement infrastructure was established in London at street level, urban background and elevated sites and contrasted against rural locations to determine the urban increment in meteorology and pollution. This approach enables understanding the seasonal variations in the meteorology and composition together with the controlling processes. In addition two intensive observation periods (IOPs) provide more detail in winter 2012 and during the Olympics in summer 2012 focusing upon the vertical structure and evolution of the urban boundary layer, chemical controls on nitrogen dioxide and ozone production, in particular the role of volatile organic compounds, and processes controlling the evolution, size, distribution and composition of particulate matter. In this talk we present early analysis of the meteorology and air quality measurements within ClearfLo. In particular we show measurements that indicate the dominant regimes of London's boundary layer.

  9. 77 FR 2715 - D'Lo Gas Storage, LLC; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-19

    ... Energy Regulatory Commission D'Lo Gas Storage, LLC; Notice of Application Take notice that on December 29, 2011, D'Lo Gas Storage, LLC (D'Lo), 1002 East St. Mary Blvd., Lafayette, Louisiana 70503, filed in... D'Lo to construct, operate, and maintain a new natural gas storage project to be located in...

  10. Proper Motion of the Leo II Dwarf Galaxy Based On Hubble Space Telescope Imaging

    NASA Astrophysics Data System (ADS)

    Piatek, Slawomir; Pryor, Carlton; Olszewski, Edward W.

    2016-12-01

    This article reports a measurement of the proper motion of Leo II, a dwarf galaxy that is a likely satellite of the Milky Way, based on imaging with the Hubble Space Telescope and Wide Field Camera 3. The measurement uses compact background galaxies as standards of rest in both channels of the camera for two distinct pointings of the telescope, as well as a QSO in one channel for each pointing, resulting in the weighted average of six measurements. The measured proper motion in the the equatorial coordinate system is (μ α ,μ δ )=(-6.9+/- 3.7,-8.7+/- 3.9) mas century-1 and in the Galactic coordinate system it is (μ ℓ,μ b)=(6.2+/- 3.9,-9.2+/- 3.7) mas century-1. The implied space velocity with respect to the Galactic center is (Π,Θ,Z) =(-37+/- 38,117+/- 43,40+/- 16) km s-1 or, expressed in Galactocentric radial and tangential components, (Vr,Vtan )=(21.9+/- 1.5,127+/- 42) km s-1. The space velocity implies that the instantaneous orbital inclination is 68°, with a 95% confidence interval of (66°,80°). The measured motion supports the hypothesis that Leo II, Leo IV, Leo V, Crater 2, and the globular cluster Crater fell into the Milky Way as a group.

  11. Price of dissension: the private wars of Dr. Leo L Spears, 1921-1956.

    PubMed

    Rehm, W S

    1995-06-01

    Anathema to the Denver medical community, favorite of the 1950s-era sensationalist press, Leo Spears and his hospital represented the complexities of chiropratic. A dynamic achiever in the face of adversity, this 1921 Palmer School graduate built the profession's first large hospital complex and had plans for an institution that would have been among the largest healthcare facilities in existence.

  12. Leo Kanner's Mention of 1938 in His Report on Autism Refers to His First Patient

    ERIC Educational Resources Information Center

    Olmsted, Dan; Blaxill, Mark

    2016-01-01

    Leo Kanner begins his landmark 1943 case series on autistic children by stating the condition was first brought to his attention in 1938. Recent letters to "JADD" have described this reference as "mysterious" and speculated it refers to papers published that year by Despert or Asperger. In fact, as Kanner goes on to state, 1938…

  13. Leo Strauss's Churchillian Speech and the Question of the Decline of the West.

    ERIC Educational Resources Information Center

    Jaffa, Harry V.

    1985-01-01

    Leo Strauss' views of the function of political philosophy as expressed in his book "Natural Right and History" are discussed. It is the function of political philosophy to distinguish good action from bad and promote the one and avert the other. (RM)

  14. Leo Strauss and the Neoconservative Critique of the Liberal University: Postmodernism, Relativism and the Culture Wars

    ERIC Educational Resources Information Center

    Peters, Michael A.

    2008-01-01

    This paper examines the neoconservative critique of the university and particularly the attack on multiculturalism and postmodernism that initiated the culture wars. It seeks to explain these developments by an analysis of the thought of Leo Strauss. The paper begins by providing an introduction to US neoconservatism and latest challenges to it…

  15. Sizing of "Mother Ship and Catcher" Concepts for LEO Small Debris Capture

    NASA Technical Reports Server (NTRS)

    Bacon, John B.

    2009-01-01

    Most Low Earth Orbit (LEO) debris lies in a limited number of inclination "bands" associated with launch latitudes, or with specific useful orbit inclinations (such as polar orbits). Such narrow inclination bands generally have a uniform spread over all possible Right Ascensions of Ascending Node (RAANs), creating a different orbit plane for nearly every piece of debris. This complicates concept of rendezvous and capture for debris removal. However, a low-orbiting satellite will always phase in RAAN faster than debris objects in higher orbits at the same inclination, potentially solving the problem. Such a base can serve as a single space-based launch facility (a "mother ship") that can tend and then send tiny individual catcher devices for each debris object, as the facility drifts into the same RAAN as the higher object. This presentation will highlight characteristic system requirements of such an architecture, including structural and navigation requirements, power, mass and dV budgets for both the mother ship and the mass-produced common catcher devices that would clean out selected inclination bands. The altitude and inclination regime over which a band is to be cleared, the size distribution of the debris, and the inclusion of additional mission priorities all affect the sizing of the system. It is demonstrated that major LEO hazardous debris reductions can be realized in each band with a single LEO launch of a single mother ship, with simple attached catchers of total mass less than typical commercial LEO launch capability.

  16. ENR selects Leo P. Duffy as its 1993 man of the year

    SciTech Connect

    Rubin, D.K.

    1993-02-15

    This article is a discussion of the appointment of Leo Duffy as the leader of the US DOE`s cleanup of its several nuclear weapons facilities. A professional sketch of Mr. Duffy is provided, and the problems that he will encounter are also outlined.

  17. Raising a Child in the Punana Leo: Everyone (Men and Women) Play an Important Role

    ERIC Educational Resources Information Center

    Iokepa-Guerrero, Noelani

    2008-01-01

    Established in 1983 by a group of parents and teachers, the 'Aha Punana Leo ('APL) was formed. A grassroots organization, 'APL was established to respond to the dismal plight of the Hawaiian language. Just a mere 25 years ago, the Hawaiian language was on the verge of being lost forever. Through the dedicated efforts of a small group of friends…

  18. On the Central Helium-burning Variable Stars of the LeoI Dwarf Spheroidal Galaxy

    NASA Astrophysics Data System (ADS)

    Fiorentino, G.; Stetson, P. B.; Monelli, M.; Bono, G.; Bernard, E. J.; Pietrinferni, A.

    2012-11-01

    We present a study of short-period, central helium-burning variable stars in the Local Group dwarf spheroidal galaxy LeoI, including 106 RR Lyrae stars and 51 Cepheids. So far, this is the largest sample of Cepheids and the largest Cepheids to RR Lyrae ratio found in such a kind of galaxy. Comparison with other Local Group dwarf spheroidals, Carina and Fornax, shows that the period distribution of RR Lyrae stars is quite similar, suggesting similar properties of the parent populations, whereas the Cepheid period distribution in LeoI peaks at longer periods (P ~ 1.26 days instead of ~0.5 days) and spans over a broader range, from 0.5 to 1.78 days. Evolutionary and pulsation predictions indicate, assuming a mean metallicity peaked within -1.5 <~ [Fe/H] <~ -1.3, that the current sample of LeoI Cepheids traces a unique mix of anomalous Cepheids (blue extent of the red-clump, partially electron-degenerate central helium-burning stars) and short-period classical Cepheids (blue-loop, quiescent central helium-burning stars). Current evolutionary prescriptions also indicate that the transition mass between the two different groups of stars is M HeF ~ 2.1 M ⊙, and it is constant for stars metal-poorer than [Fe/H] ~ -0.7. Finally, we briefly outline the different implications of the current findings on the star formation history of LeoI.

  19. Establishing a Robotic, LEO-to-GEO Satellite Servicing Infrastructure as an Economic Foundation for Exploration

    NASA Technical Reports Server (NTRS)

    Horsham, Gary A. P.; Schmidt, George R.; Gilland, James H.

    2010-01-01

    The strategy for accomplishing civilian exploration goals and objectives is in the process of a fundamental shift towards a potential new approach called Flexible Path. This paper suggests that a government-industry or public-private partnership in the commercial development of low Earth orbit to geostationary orbit (LEO-to-GEO (LTG)) space, following or in parallel with the commercialization of Earth-to-LEO and International Space Station (ISS) operations, could serve as a necessary, logical step that can be incorporated into the flexible path approach. A LTG satellite-servicing infrastructure and architecture concept is discussed within this new strategic context. The concept consists of a space harbor that serves as a transport facility for a fleet of specialized, fully- or semi-autonomous robotic servicing spacecraft. The baseline, conceptual system architecture is composed of a space harbor equipped with specialized servicer spacecraft; a satellite command, communication, and control system; a parts station; a fuel station or depot; and a fuel/parts replenishment transport. The commercial servicer fleet would consist of several types of spacecraft, each designed with specialized robotic manipulation subsystems to provide services such as refueling, upgrade, repair, inspection, relocation, and removal. The space harbor is conceptualized as an ISS-type, octagonal truss structure equipped with radiation tolerant subsystems. This space harbor would be primarily capable of serving as an operational platform for various commercially owned and operated servicer spacecraft positioned and docked symmetrically on four of the eight sides. Several aspects of this concept are discussed, such as: system-level feasibility in terms of ISS-truss-type infrastructure and subsystems emplacement and maintenance between LEO and GEO; infrastructure components assembly in LEO, derived from ISS assembly experience, and transfer to various higher orbital locations; the evolving Earth

  20. LEO P: HOW MANY METALS CAN A VERY LOW MASS, ISOLATED GALAXY RETAIN?

    SciTech Connect

    McQuinn, Kristen B. W.; Skillman, Evan D.; Dolphin, Andrew; Cannon, John M.; Salzer, John J.; Rhode, Katherine L.; Adams, Elizabeth A. K.; Berg, Danielle; Giovanelli, Riccardo; Haynes, Martha P.

    2015-12-20

    Leo P is a gas-rich dwarf galaxy with an extremely low gas-phase oxygen abundance (3% solar). The isolated nature of Leo P enables a quantitative measurement of metals lost solely due to star formation feedback. We present an inventory of the oxygen atoms in Leo P based on the gas-phase oxygen abundance measurement, the star formation history (SFH), and the chemical enrichment evolution derived from resolved stellar populations. The SFH also provides the total amount of oxygen produced. Overall, Leo P has retained 5% of its oxygen; 25% of the retained oxygen is in the stars while 75% is in the gas phase. This is considerably lower than the 20%–25% calculated for massive galaxies, supporting the trend for less efficient metal retention for lower-mass galaxies. The retention fraction is higher than that calculated for other alpha elements (Mg, Si, Ca) in dSph Milky Way satellites of similar stellar mass and metallicity. Accounting only for the oxygen retained in stars, our results are consistent with those derived for the alpha elements in dSph galaxies. Thus, under the assumption that the dSph galaxies lost the bulk of their gas mass through an environmental process such as tidal stripping, the estimates of retained metal fractions represent underestimates by roughly a factor of four. Because of its isolation, Leo P provides an important datum for the fraction of metals lost as a function of galaxy mass due to star formation.

  1. Leo P: How Many Metals Can a Very Low Mass, Isolated Galaxy Retain?

    NASA Astrophysics Data System (ADS)

    McQuinn, Kristen B. W.; Skillman, Evan D.; Dolphin, Andrew; Cannon, John M.; Salzer, John J.; Rhode, Katherine L.; Adams, Elizabeth A. K.; Berg, Danielle; Giovanelli, Riccardo; Haynes, Martha P.

    2015-12-01

    Leo P is a gas-rich dwarf galaxy with an extremely low gas-phase oxygen abundance (3% solar). The isolated nature of Leo P enables a quantitative measurement of metals lost solely due to star formation feedback. We present an inventory of the oxygen atoms in Leo P based on the gas-phase oxygen abundance measurement, the star formation history (SFH), and the chemical enrichment evolution derived from resolved stellar populations. The SFH also provides the total amount of oxygen produced. Overall, Leo P has retained 5% of its oxygen; 25% of the retained oxygen is in the stars while 75% is in the gas phase. This is considerably lower than the 20%-25% calculated for massive galaxies, supporting the trend for less efficient metal retention for lower-mass galaxies. The retention fraction is higher than that calculated for other alpha elements (Mg, Si, Ca) in dSph Milky Way satellites of similar stellar mass and metallicity. Accounting only for the oxygen retained in stars, our results are consistent with those derived for the alpha elements in dSph galaxies. Thus, under the assumption that the dSph galaxies lost the bulk of their gas mass through an environmental process such as tidal stripping, the estimates of retained metal fractions represent underestimates by roughly a factor of four. Because of its isolation, Leo P provides an important datum for the fraction of metals lost as a function of galaxy mass due to star formation. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  2. Ground-based simulation of LEO environment: Investigations of a select LDEF material: FEP Teflon (trademark)

    NASA Technical Reports Server (NTRS)

    Cross, Jon B.; Koontz, Steven L.

    1993-01-01

    The Long Duration Exposure Facility (LDEF) has produced a wealth of data on materials degradation in the low earth orbit (LEO) space environment and has conclusively shown that surface chemistry (as opposed to surface physics-sputtering) is the key to understanding and predicting the degradation of materials in the LEO environment. It is also clear that materials degradation and spacecraft contamination are closely linked and that the fundamental mechanisms responsible for this linking are in general not well understood especially in the area of synergistic effects. The study of the fundamental mechanisms underlying materials degradation in LEO is hampered by the fact that the degradation process itself is not observed during the actual exposure to the environment. Rather the aftermath of the degradation process is studied, i.e., the material that remains after exposure is observed and mechanisms are proposed to explain the observed results. The EOIM-3 flight experiment is an attempt to bring sophisticated diagnostic equipment into the space environment and monitor the degradation process in real time through the use of mass spectrometry. More experiments of this nature which would include surface sensitive diagnostics (Auger and photoelectron spectroscopes) are needed to truly unravel the basic chemical mechanisms involved in the materials degradation process. Since these in-space capabilities will most likely not be available in the near future, ground-based LEO simulation facilities employing sophisticated diagnostics are needed to further advance the basic understanding of the materials degradation mechanisms. The LEO simulation facility developed at Los Alamos National Laboratory has been used to investigate the atomic oxygen/vacuum ultraviolet (AO/VUV) enhanced degradation of FEP Teflon. The results show that photo-ejection of polymer fragments occur at elevated temperature (200 C), that VUV synergistic rare gas sputtering of polymer fragments occur even at

  3. Alfalfa discovery of the nearby gas-rich dwarf galaxy Leo P. IV. Distance measurement from LBT optical imaging

    SciTech Connect

    McQuinn, Kristen B. W.; Skillman, Evan D.; Berg, Danielle; Cannon, John M.; Salzer, John J.; Rhode, Katherine L.; Adams, Elizabeth A. K.; Giovanelli, Riccardo; Haynes, Martha P.; Dolphin, Andrew E-mail: skillman@astro.umn.edu E-mail: jcannon@macalester.edu E-mail: slaz@astro.indiana.edu E-mail: riccardo@astro.cornell.edu

    2013-12-01

    Leo P is a low-luminosity dwarf galaxy discovered through the blind H I Arecibo Legacy Fast ALFA survey. The H I and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with both active star formation and an underlying older population, as well as an extremely low oxygen abundance. Here, we measure the distance to Leo P by applying the tip of the red giant branch (TRGB) distance method to photometry of the resolved stellar population from new Large Binocular Telescope V and I band imaging. We measure a distance modulus of 26.19{sub −0.50}{sup +0.17} mag corresponding to a distance of 1.72{sub −0.40}{sup +0.14} Mpc. Although our photometry reaches 3 mag below the TRGB, the sparseness of the red giant branch yields higher uncertainties on the lower limit of the distance. Leo P is outside the Local Group with a distance and velocity consistent with the local Hubble flow. While located in a very low-density environment, Leo P lies within ∼0.5 Mpc of a loose association of dwarf galaxies which include NGC 3109, Antlia, Sextans A, and Sextans B, and 1.1 Mpc away from its next nearest neighbor, Leo A. Leo P is one of the lowest metallicity star-forming galaxies known in the nearby universe, comparable in metallicity to I Zw 18 and DDO 68, but with stellar characteristics similar to dwarf spheriodals (dSphs) in the Local Volume such as Carina, Sextans, and Leo II. Given its physical properties and isolation, Leo P may provide an evolutionary link between gas-rich dwarf irregular galaxies and dSphs that have fallen into a Local Group environment and been stripped of their gas.

  4. Balmer Absorption Lines in FeLoBALs

    NASA Astrophysics Data System (ADS)

    Aoki, K.; Iwata, I.; Ohta, K.; Tamura, N.; Ando, M.; Akiyama, M.; Kiuchi, G.; Nakanishi, K.

    2007-10-01

    We discovered non-stellar Balmer absorption lines in two many-narrow-trough FeLoBALs (mntBALs) by the near-infrared spectroscopy with Subaru/CISCO. Presence of the non-stellar Balmer absorption lines is known to date only in the Seyfert galaxy NGC 4151; thus our discovery is the first cases for quasars. Since all known active galactic nuclei with Balmer absorption lines share similar characteristics, it is suggested that there is a population of BAL quasars which have unique structures at their nuclei or unique evolutionary phase.

  5. Photometry of LO Pegasi in B, V, R colors

    NASA Astrophysics Data System (ADS)

    Csorvási, R.

    2006-09-01

    Variable magnetic activity manifested by starspot distribution is investigated on the single K5-K7 dwarf LO Peg, using one month long photometric observations. We supposed three circular spots for light curve solution. We find variable spot temperature, whose average is 3960 K. The sizes of spots were stable for two spots and one spot showed a significant decrease. Different migration periods on two spots indicate differential rotation, the magnitude of the migration is slow. During the measured 90 stellar rotations (38.5 days) the location of the activity remained on the same hemisphere of the star.

  6. Advanced liquid oxygen (LO2) propellant conditioning concept testing

    NASA Technical Reports Server (NTRS)

    Perry, G. L. E.; Suter, J. D.; Turner, S. G.

    1995-01-01

    Advanced methods of liquid oxygen (LO2) propellant conditioning were studied as part of an effort for increasing reliability and operability while reducing cost of future heavy lift launch vehicles. The most promising conditioning concept evaluated was no-bleed (passive recirculation) followed by low-bleed, helium injection, and use of a recirculation line. Full-scale cryogenic testing was performed with a sloped feedline test article to validate models of behavior of LO2 in the feedline and to prove no-bleed feasibility. Test data are also intended to help generate design guidelines for the development of a main propulsion system feed duct. A design-of-experiments matrix of over 100 tests was developed to test all four propellant conditioning concepts and the impact of design parameters on the concepts. Liquid nitrogen was used as the test fluid. The work for this project was conducted from October 1992 through January 1994 at the hydrogen cold flow facility of the west test area of MSFC. Test data have shown that satisfactory temperatures are being obtained for the no-bleed conditioning concept.

  7. Fast optically sectioned fluorescence HiLo endomicroscopy

    PubMed Central

    Lim, Daryl; Mertz, Jerome

    2012-01-01

    Abstract. We describe a nonscanning, fiber bundle endomicroscope that performs optically sectioned fluorescence imaging with fast frame rates and real-time processing. Our sectioning technique is based on HiLo imaging, wherein two widefield images are acquired under uniform and structured illumination and numerically processed to reject out-of-focus background. This work is an improvement upon an earlier demonstration of widefield optical sectioning through a flexible fiber bundle. The improved device features lateral and axial resolutions of 2.6 and 17 μm, respectively, a net frame rate of 9.5 Hz obtained by real-time image processing with a graphics processing unit (GPU) and significantly reduced motion artifacts obtained by the use of a double-shutter camera. We demonstrate the performance of our system with optically sectioned images and videos of a fluorescently labeled chorioallantoic membrane (CAM) in the developing G. gallus embryo. HiLo endomicroscopy is a candidate technique for low-cost, high-speed clinical optical biopsies. PMID:22463023

  8. Volcanic Activity on lo at the Time of the Ulysses Encounter.

    PubMed

    Spencer, J R; Howell, R R; Clark, B E; Klassen, D R; O'connor, D

    1992-09-11

    The population of heavy ions in lo's torus is ultimately derived from lo volcanism. Groundbased infrared observations of lo between October 1991 and March 1992, contemporaneous with the 8 February 1992 Ulysses observations of the lo torus, show that volcanic thermal emission was at the low end of the normal range at all lo longitudes during this period. In particular, the dominant hot spot Loki was quiescent. Resolved images show that there were at least four hot spots on lo's Jupiter-facing hemisphere, including Loki and a long-lived spot on the leading hemisphere (Kanehekili), of comparable 3.5-micrometer brightness but higher temperature.

  9. A FIRST MEASUREMENT OF THE PROPER MOTION OF THE LEO II DWARF SPHEROIDAL GALAXY

    SciTech Connect

    Lepine, Sebastien; Koch, Andreas; Rich, R. Michael; Kuijken, Konrad

    2011-11-10

    We use 14 year baseline images obtained with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope (HST) to derive a proper motion for one of the Milky Way's most distant dwarf spheroidal companions, Leo II, relative to an extragalactic background reference frame. Astrometric measurements are performed in the effective point-spread function formalism using our own developed code. An astrometric reference grid is defined using 3224 stars that are members of Leo II and brighter than a magnitude of 25 in the F814W band. We identify 17 compact extragalactic sources, for which we measure a systemic proper motion relative to this stellar reference grid. We derive a proper motion [{mu}{sub {alpha},{mu}{delta}}] = [+104 {+-}113,-33 {+-} 151] {mu}as yr{sup -1} for Leo II in the heliocentric reference frame. Though marginally detected, the proper motion yields constraints on the orbit of Leo II. Given a distance of d {approx_equal} 230 kpc and a heliocentric radial velocity v{sub r} = +79 km s{sup -1}, and after subtraction of the solar motion, our measurement indicates a total orbital motion v{sub G} = 266.1 {+-} 128.7 km s{sup -1} in the Galactocentric reference frame, with a radial component v{sub r{sub G}}=21.5{+-}4.3 km s{sup -1} and tangential component v{sub t{sub G}} = 265.2 {+-} 129.4 km s{sup -1}. The small radial component indicates that Leo II either has a low-eccentricity orbit or is currently close to perigalacticon or apogalacticon distance. We see evidence for systematic errors in the astrometry of the extragalactic sources which, while close to being point sources, are slightly resolved in the HST images. We argue that more extensive observations at later epochs will be necessary to better constrain the proper motion of Leo II. We provide a detailed catalog of the stellar and extragalactic sources identified in the HST data which should provide a solid early-epoch reference for future astrometric measurements.

  10. Overview of battery usage in NASA/GSFC LEO and GEO missions

    NASA Technical Reports Server (NTRS)

    Yi, Thomas

    1989-01-01

    In July, 1989, Cosmic Background Explorer (COBE) will be launched from a Delta rocket to study the big bang theory. The COBE, which is in a LEO/Polar orbit, will have two 20 Ah NiCd batteries, and 18 cells per battery, made by McDonnell Douglas Company. In December, 1989, National Oceanic and Atmospheric Administration (NOAA-D) will be launched from an Atlas rocket for weather observation purposes. NOAA-D, which is in a LEO/Polar morning orbit, will have two 26.5 Ah NiCd batteries, and 17 cells per battery, made by Ge-Astro East Windor. NOAA-I, which is scheduled for May, 1991 launch in a LEO/Polar afternoon orbit, will have three 26.5 Ah NiCd batteries, 17 cells per battery, made by GE-Astro East Windor. In April, 1990, Gamma Ray Observatory (GRO) will be launched from STS37 to study the gamma ray radiation phenomenon. GRO, which is in a LEO orbit, will have two modular power systems (MPS) made by McDonnell Douglas, each MPS consisting of three 50 Ah NiCd batteries, 22 cells per battery. In July, 1990, Geostationary Operational Environmental Satellite (GOES-I) will be launched from an Atlas I rocket for weather observation purposes. GOES-I, which is in a GEO orbit, will have two 12 Ah NiCd batteries, 28 cells per battery, made by Ford Aerospace and Communications Company. In December, 1990, Tracking and Data Relay Satellite (TDRS-E) will be launched from STS43 for communication purposes. TDRS-E, which is in a GEO orbit, will have three 40 Ah NiCd batteries, 24 cells per battery, made by TRW. In August, 1991, Extreme Ultraviolet Explorer (EUVE) will be launched from a Delta rocket. EUVE, which is in a LEO orbit, will have one modular power system (MPS) made by McDonnell Douglas. In December, 1991, Upper Atmosphere Research Satellite (UARS) will be launched from STS50 to study the Earth's ozone layer and other environmental concerns. UARS, which is in a 56 deg inclination LEO orbit, will have one modular power systems (MPS) made by McDonnell Douglas.

  11. The chemical abundances of the stellar populations in the Leo I and II dSph galaxies

    NASA Astrophysics Data System (ADS)

    Bosler, Tammy L.; Smecker-Hane, Tammy A.; Stetson, Peter B.

    2007-06-01

    We have obtained calcium abundances and radial velocities for 102 red giant branch (RGB) stars in the Leo I dwarf spheroidal galaxy (dSph) and 74 RGB stars in the Leo II dSph using the low-resolution spectrograph (LRIS) on the Keck I 10-m telescope. We report on the calcium abundances [Ca/H] derived from the strengths of the CaII triplet absorption lines at 8498, 8542 and 8662 Å in the stellar spectra using a new empirical CaII triplet calibration to [Ca/H]. The two galaxies have different average [Ca/H] values of -1.34 +/- 0.02 for Leo I and -1.65 +/- 0.02 for Leo II with intrinsic abundance dispersions of 1.2 and 1.0 dex, respectively. The typical random and total errors in derived abundances are 0.10 and 0.17 dex per star. For comparison to the existing literature, we also converted our CaII measurements to [Fe/H] on the scale of Carretta and Gratton (1997) though we discuss why this may not be the best determinant of metallicity; Leo I has a mean [Fe/H] = -1.34 and Leo II has a mean [Fe/H] = -1.59. The metallicity distribution function of Leo I is approximately Gaussian in shape with an excess at the metal-rich end, while that of Leo II shows an abrupt cut-off at the metal-rich end. The lower mean metallicity of Leo II is consistent with the fact that it has a lower luminosity, hence lower the total mass than Leo I; thus, the evolution of Leo II may have been affected more by mass lost in galactic winds. Our direct and independent measurement of the metallicity distributions in these dSph will allow a more accurate star-formation histories to be derived from future analysis of their colour-magnitude diagrams(CMDs). Data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. E

  12. Ontogeny of fetal CD8lo4lo thymocytes: expression of CD44, CD25 and early expression of TcR alpha mRNA.

    PubMed

    Andjelić, S; Jain, N; Nikolić-Zugić, J

    1993-09-01

    CD8lo4lo cells are the immediate precursors of immature CD8hi4loTcRlo, CD8lo4hiTcRlo and CD8hi4hiTcRlo double-positive (DP) thymocytes in the adult murine thymus. These cells are the first subset in the adult thymus to express accessory CD8 and CD4 molecules, to rearrange the T cell receptor (TcR) alpha chain genes and to express the TcR alpha beta heterodimer at low levels at the surface. Here, we investigate the fetal ontogeny of CD8lo4lo cells. We detect these cells on day 15 of fetal development. They dominate the thymus on day 15.5, to become progressively less prominent thereafter. An important characteristic of fetal CD8lo4lo cells is the early expression of TcR alpha mRNA (on fetal day 15, 36-48 h earlier than reported previously). Our results also suggest, but do not prove, that the receptor may be expressed on the surface as early as day 15.5. Fetal CD8lo4lo cells, like their adult counterparts, become DP in vitro. However, early fetal CD8lo4lo thymocytes express both CD44 and CD25--unlike the adult subset--and that links them to their putative precursors, fetal CD44+CD25+ double-negative cells. This finding underscores the difference between adult and fetal thymocytes in turnover of membrane molecules and/or the kinetics of progression through phenotypic stages.

  13. Responsivity calibration of the LoWEUS spectrometer

    SciTech Connect

    Lepson, J. K.; Beiersdorfer, P.; Kaita, R.; Majeski, R.; Boyle, D.

    2016-09-02

    We performed an in situ calibration of the relative responsivity function of the Long-Wavelength Extreme Ultraviolet Spectrometer (LoWEUS), while operating on the Lithium Tokamak Experiment (LTX) at Princeton Plasma Physics Laboratory. The calibration was accomplished by measuring oxygen lines, which are typically present in LTX plasmas. The measured spectral line intensities of each oxygen charge state were then compared to the calculated emission strengths given in the CHIANTI atomic database. Normalizing the strongest line in each charge state to the CHIANTI predictions, we obtained the differences between the measured and predicted values for the relative strengths of the other lines of a given charge state. We find that a 3rd degree polynomial function provides a good fit to the data points. Lastly, our measurements show that the responsivity between about 120 and 300 Å varies by factor of ~30.

  14. Responsivity calibration of the LoWEUS spectrometer

    NASA Astrophysics Data System (ADS)

    Lepson, J. K.; Beiersdorfer, P.; Kaita, R.; Majeski, R.; Boyle, D.

    2016-11-01

    We performed an in situ calibration of the relative responsivity function of the Long-Wavelength Extreme Ultraviolet Spectrometer (LoWEUS), while operating on the Lithium Tokamak Experiment (LTX) at Princeton Plasma Physics Laboratory. The calibration was accomplished by measuring oxygen lines, which are typically present in LTX plasmas. The measured spectral line intensities of each oxygen charge state were then compared to the calculated emission strengths given in the CHIANTI atomic database. Normalizing the strongest line in each charge state to the CHIANTI predictions, we obtained the differences between the measured and predicted values for the relative strengths of the other lines of a given charge state. We find that a 3rd degree polynomial function provides a good fit to the data points. Our measurements show that the responsivity between about 120 and 300 Å varies by factor of ˜30.

  15. Responsivity calibration of the LoWEUS spectrometer

    DOE PAGES

    Lepson, J. K.; Beiersdorfer, P.; Kaita, R.; ...

    2016-09-02

    We performed an in situ calibration of the relative responsivity function of the Long-Wavelength Extreme Ultraviolet Spectrometer (LoWEUS), while operating on the Lithium Tokamak Experiment (LTX) at Princeton Plasma Physics Laboratory. The calibration was accomplished by measuring oxygen lines, which are typically present in LTX plasmas. The measured spectral line intensities of each oxygen charge state were then compared to the calculated emission strengths given in the CHIANTI atomic database. Normalizing the strongest line in each charge state to the CHIANTI predictions, we obtained the differences between the measured and predicted values for the relative strengths of the other linesmore » of a given charge state. We find that a 3rd degree polynomial function provides a good fit to the data points. Lastly, our measurements show that the responsivity between about 120 and 300 Å varies by factor of ~30.« less

  16. MaTeLo: Automated Testing Suite for Software Validation

    NASA Astrophysics Data System (ADS)

    Guiotto, A.; Acquaroli, B.; Martelli, A.

    It is universally known that testing has a predominant role when developing software: more and more efforts are spent on testing to detect programming faults, to evaluate the code reliability or performance, to ensure that a critical function of a system meets given requirements. The ratio of time spent on testing should not be neglected and this explains why there is a real need to improve the development process, especially as systems are becoming larger and larger. It is necessary to keep under control the schedule and budget of developments, and controlling the testing phase is a real issue, often underestimated in many industrial sectors. The industry is heightened at different stages regarding testing, and the MaTeLo project is committed to promote the use of statistical tools &methods to answer European industry's needs: • have the ability to choose relevant test cases instead of a human- biased selection • know when to stop testing (definition of a stopping criteria) instead of a vague and informal criteria • adopt an identical strategy for different developments • automate the testing process, and thus to make testing not human error prone MaTeLo (Markov Test Logic) study is a study currently under development in the frame of the IST program of the European Community. The aim of the project is to define, implement and validate a new approach for supporting the software testing activities in various industrial fields. One of the major goals is in particular to provide the software teams with a new tool able to automatically produce and execute the Test Cases starting from the software specifications. Further, the tool is conceived to provide metrics that could help technical staff to determine software quality and to evaluate how much expected results are met. The tool is based on Markov chains theory and belongs to statistical testing software tools family [Runeson] [Whittaker].

  17. Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cell - Update II

    NASA Technical Reports Server (NTRS)

    Smithrick, John J.; Hall, Stephen W.

    1992-01-01

    An update of validation test results confirming the breakthrough in LEO cycle life of nickel-hydrogen cells containing 26 percent KOH electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel (IPV) nickel-hydrogen cells has been previously reported. The cycle life of boiler plate cells containing 26 percent potassium hydroxide (KOH) electrolyte was about 40,000 LEO cycles, compared to 3500 cycles for cells containing 31 percent KOH. The cycle regime was a stressful accelerated LEO, which consisted of a 27.5 min charge followed by a 17.5 min discharge (2X normal rate). The depth-of-discharge was 80 percent. Six 48-Ah Hughes recirculation design IPV nickel-hydrogen flight battery cells are being evaluated. Three of the cells contain 26 percent KOH (test cells), and three contain 31 percent KOH (control cells). They are undergoing real time LEO cycle life testing. The cycle regime is a 90-min LEO orbit consisting of a 54-min charge followed by a 36-min discharge. The depth-of-discharge is 80 percent. The cell temperature is maintained at 10 C. The three 31 percent KOH cells failed (cycles 3729, 4165, and 11355). One of the 26 percent KOH cells failed at cycle 15314. The other two 26 percent KOH cells were cycled for over 16,000 cycles during the continuing test.

  18. Adaptive Optics for Satellite and Debris Imaging in LEO and GEO

    NASA Astrophysics Data System (ADS)

    Copeland, M.; Bennet, F.; Zovaro, A.; Riguat, F.; Piatrou, P.; Korkiakoski, V.; Smith, C.

    2016-09-01

    The Research School of Astronomy and Astrophysics (RSAA) at the Australian National University has developed and Adaptive Optics (AO) system for satellite and debris imaging in low Earth orbit (LEO) and geostationary orbit (GEO). In LEO the size, shape and orientation of objects will be measured with resolution of 50 cm for objects at 800 km range at an 800 nm imaging wavelength. In GEO satellite position will be measured using precision astrometry of nearby stars. We use an AO system with a deformable mirror (DM) of 277 actuators and Shack-Hartmann wavefront sensor operating at 2 kHz. Imaging is performed at a rate of >30 Hz to reduce image blur due to tip-tilt and rotation. We use two imaging modes; a high resolution mode to obtain Nyquist sampled images and a acquisition mode with 75 arcsecond field of view to aid in finding targets.

  19. Ageing of Sony 18650HC Cells in LEO LifeTests

    NASA Astrophysics Data System (ADS)

    Dudley, G.; Buckle, R.; Hendel, B.; Mattle, T.; Spurrett, R.

    2008-09-01

    Results of a long-duration LEO life-test of a battery comprised of 72 Sony 18650HC cells are presented. The ongoing test, started in late 1999, has reached 84,000 cycles, equivalent to more than 14 years in LEO orbit at an acceleration factor of 1.7. Most cells have remained balanced in state of charge during the test but a few have dropped up to 150 mV in end of charge voltage and at the same time exhibited higher than average internal resistances. The battery continues to out-perform the predictions of the ABSL 'LIFE' model. A cell model developed at ESTEC is used to try to gain some insight into the cell ageing processes.

  20. LENTICULAR GALAXIES AT THE OUTSKIRTS OF THE LEO II GROUP: NGC 3599 AND NGC 3626

    SciTech Connect

    Sil'chenko, O. K.; Shulga, A. P.; Moiseev, A. V. E-mail: alina.shulga@gmail.co

    2010-11-15

    We have studied unbarred S0 galaxies, NGC 3599 and NGC 3626, the members of the X-ray bright group Leo II, by means of three-dimensional spectroscopy, long-slit spectroscopy, and imaging, with the aim of identifying the epoch and mechanisms of their transformation from spirals. Both galaxies have appeared to bear complex features obviously resulting from minor merging: decoupled gas kinematics, nuclear star-forming rings, and multi-tiered oval large-scale stellar disks. The weak emission line nucleus of NGC 3599 bears all signs of Seyfert activity, according to the line-ratio diagnostics of the gas excitation mechanism. We conclude that the transformation of these lenticular galaxies took place about 1-2 Gyr ago, through gravitational mechanisms unrelated to the hot intragroup medium of Leo II.

  1. Time Serial Analysis of the Induced LEO Environment within the ISS 6A

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Nealy, John E.; Tomov, B. T.; Cucinotta, Francis A.; Badavi, Frank F.; DeAngelis, Giovanni; Atwell, William; Leutke, N.

    2006-01-01

    Anisotropies in the low Earth orbit (LEO) radiation environment were found to influence the thermoluminescence detectors (TLD) dose within the (International Space Station) ISS 7A Service Module. Subsequently, anisotropic environmental models with improved dynamic time extrapolation have been developed including westward and northern drifts using AP8 Min & Max as estimates of the historic spatial distribution of trapped protons in the 1965 and 1970 era, respectively. In addition, a directional dependent geomagnetic cutoff model was derived for geomagnetic field configurations from the 1945 to 2020 time frame. A dynamic neutron albedo model based on our atmospheric radiation studies has likewise been required to explain LEO neutron measurements. The simultaneous measurements of dose and dose rate using four Liulin instruments at various locations in the US LAB and Node 1 has experimentally demonstrated anisotropic effects in ISS 6A and are used herein to evaluate the adequacy of these revised environmental models.

  2. The Impact of Ionospheric Delay on the Frequency Transfer Utilizing A LEO Satellite

    NASA Astrophysics Data System (ADS)

    Tian, Shi-Wei; Xu, Rong; Yu, Yong; Chang, Jiang; Li, Guang-Xia

    2015-04-01

    Using the frequency of assisted signals transferred by a LEO (Low Earth Orbit) satellite to extend the coherence time of inexpensive GNSS (Global Navigation Satellite System) receiver clocks is one of the most effective methods to improve the performance of the GNSS receivers that may be in hostile environments or subject to interference. Among the factors affecting the results of frequency transfer, ionospheric delay is the most important one. In this work, the principles for frequency transfer utilizing an LEO satellite and the corresponding error sources are analyzed. Especially, the impact of ionospheric delay is ana- lyzed, and a correction method utilizing the ionospheric delay difference between the neighboring epoches and that between two stations is presented. Simulations are performed to validate the above analysis and correction method. The results show that with the correction proposed in this paper, the requirements for the frequency transfer can be met.

  3. Super NiCd Open-Circuit Storage and Low Earth Orbit (LEO) Life Test Evaluation

    NASA Technical Reports Server (NTRS)

    Baer, Jean Marie; Hwang, Warren C.; Ang, Valerie J.; Hayden, Jeff; Rao, Gopalakrishna; Day, John H. (Technical Monitor)

    2002-01-01

    This presentation discusses Air Force tests performed on super NiCd cells to measure their performance under conditions simulating Low Earth Orbit (LEO) conditions. Super NiCd cells offer potential advantages over existing NiCd cell designs including advanced cell design with improved separator material and electrode making processes, but handling and storage requires active charging. These tests conclude that the super NiCd cells support generic Air Force qualifications for conventional LEO missions (up to five years duration) and that handling and storage may not actually require active charging as previously assumed. Topics covered include: Test Plan, Initial Characterization Tests, Open-Circuit Storage Tests, and post storage capacities.

  4. Research on Long-Term Orbit Propagation for Space Debris in LEO

    NASA Astrophysics Data System (ADS)

    Peng, Keke; Pang, Baojun; Xiao, Weike

    2013-08-01

    Space debris long-term orbit propagation is one of the main problems for the space debris environment models. The evolution of space debris in low Earth orbit (LEO) is determined by a complex interplay of different perturbations. The aim of this paper is to investigate the long-term effects of the most dominating perturbations: Earth geopotential effects, atmospheric drag, luni-solar perturbations and solar radiation pressure. The atmospheric drag is the major non-gravitational perturbation in LEO. This article provides an average method of numerical integration on one revolution for rotating and stationary atmosphere, and then one can make use of various atmospheric densities to calculate the orbital evolution. Using this method, we have analyzed the effects of rotating and stationary atmospheric drag perturbation on orbital lifetime. The results show the effects of solar activity and geomagnetic index on orbital evolution are obvious. The lifetime difference in rotating atmosphere is mostly depending on inclinations of space debris.

  5. Positive immunolabelling for feline infectious peritonitis in an African lion (Panthera leo) with bilateral panuveitis.

    PubMed

    Mwase, M; Shimada, K; Mumba, C; Yabe, J; Squarre, D; Madarame, H

    2015-01-01

    A 15-year-old male African lion (Panthera leo) was presented with blindness due to bilateral panuveitis with retinal detachment. Feline coronavirus (FCoV) antigen was identified immunohistochemically in ocular macrophages, consistent with a diagnosis of feline infectious peritonitis (FIP) infection. This is the first report of FIP in an African lion and the first report of ocular FIP in a non-domestic felid.

  6. Leo Stent for Endovascular Treatment of Broad-Necked and Fusiform Intracranial Aneurysms

    PubMed Central

    Juszkat, R.; Nowak, S.; Smól, S.; Kociemba, W.; Blok, T.; Zarzecka, A.

    2007-01-01

    Summary The advent of intracranial stents has widened the indications for endovascular treatment of broad-necked and fusiform aneurysms. Leo stent is a self-expandable, nitinol, braided stent dedicated to intracranial vessels. The aim of this study is to present our experience in endovascular treatment of broad-necked and fusiform intracranial aneurysms using self-expanding, nitinol Leo stents. Between February 2004 and November 2006, 25 broad-necked and three fusiform aneurysms in 28 patients were treated using Leo stents in our centre. There were 18 patients who experienced acute subarachnoid haemorrhage due to aneurysm rupture, two patients who experienced SAH at least 12 months ago and in eight patients aneurysms were found incidentally. Aneurysms were located as follows: internal carotid artery15, basilar artery5, basilar tip3, posterior inferior cerebral artery2, M1/M2 segment1, A2 segment1 and vertebral artery1. There were no difficulties with stent deployment and delivery. All patients after acute SAH (n=18) underwent stent implantation and coil embolization in one procedure. The remaining patients underwent coil embolization in a staged procedure. Immediate aneurysm occlusion of more than 95% was achieved in all patients who underwent stent placement and coil embolization in one procedure. There were three thromboembolic complications encountered in patients in an acute setting of SAH, preloaded only on acetylsalicylic acid. Use of abciximab led to patency within the stent and parent vessel. However, one of these patients presented rebleeding from the aneurysm during administration of abciximab and died. Application of Leo stents in cases of broadnecked and fusiform intracranial aneurysms is safe and effective with a low complication rate. PMID:20566117

  7. VizieR Online Data Catalog: Galaxies in Leo/Cnc region (Karachentsev+, 2015)

    NASA Astrophysics Data System (ADS)

    Karachentsev, I. D.; Nasonova, O. G.; Karachentseva, V. E.

    2015-02-01

    The table contains original observational data on 543 galaxies in the Leo/Cancer region. The initial sample was extracted from HyperLeda Database; then fictitious "galaxies" (72%) were removed. Selecting the galaxies in our list, we also checked and updated their different characteristics. In particular, we have determined distances for 139 galaxies from the Tully-Fisher relation. The resulting sample includes 290 galaxies with individual distance estimates. (1 data file).

  8. Natural law Judaism? The genesis of bioethics in Hans Jonas, Leo Strauss, and Leon Kass.

    PubMed

    Vogel, Lawrence

    2006-01-01

    Leon Kass is much misunderstood. He is not simply a Republican ideologue who tailored his ideas to break out of the ivory tower and into the halls of power. Nor does he look simply to use human nature as a moral guide. When the full range of his writings is considered and set in the tradition of his teachers, Hans Jonas and Leo Strauss, what emerges is a natural law position colored by religious revelation.

  9. MEO and LEO space debris optical observations at Crimean Observatory: first experience and future perspectives.

    NASA Astrophysics Data System (ADS)

    Rumyantsev, Vasilij; Biryukov, Vadim; Agapov, Vladimir; Molotov, Igor

    The near Earth space observation group of Crimean Observatory is performing the regular op-tical monitoring of space debris at GEO region within framework of the International Scientific Optical Network (ISON). During last years we also paid attention to objects on lower orbits due to increasing interest to LEO and MEO regions caused by several catastrophic events happened in the recent past. Optical observations provide high quality information about position and physical properties of space debris at LEO and MEO so they can be considered as another source of data comple-mentary to traditional radar measurements. We will discuss our observations of fragments from Briz-M upper stage (object 28944) and Block-DM ullage motor (25054) explosions. Results of observation of USA-193 debris will be presented. Then we will focus on observations and some photometric properties of FengYun 1C debris as well as Cosmos 2251 and Iridium 33 fragments. Radar cross-section versus optical photometry will be compared. Moreover, estimates of orbital parameters as well as area-to-mass ratio for some observed objects will be given. Most of our observations which we discuss in the paper represent just the first attempt to investigate capabilities of our optical system to observe MEO and LEO objects. But these results are very promising and show good perspectives for the future. We will briefly describe future perspectives of our optical observations of space debris and other objects in MEO and LEO region after the new wide-field telescopes will be put into operation.

  10. VES100/140 Lithium-Ion Cells LEO Life-Test Results & Protheus Flight Heritage

    NASA Astrophysics Data System (ADS)

    Borthomieu, Y.; Prevot, D.; Massot, J.; Tastet, P.; Simon, E.

    2011-10-01

    This paper assesses from Low Earth Orbit (LEO) life tests results the influence of the cycling parameters such as Depth Of Discharge (DOD), End Of Charge Voltage (EOCV) & charge current on VES100/140 cell electrical performances. It also demonstrates a good correlation between the cells ageing predicted by the Saft Li-Ion Model (SLIM) tool and the real behavior of these cells under life-tests or in flight on board "Calipso" satellite after more than 5 years in orbit.

  11. A Search for Stellar Dust Production in Leo P, a Nearby Analog of High Redshift Galaxies

    NASA Astrophysics Data System (ADS)

    Boyer, Martha; McDonald, Iain; McQuinn, Kristen; Skillman, Evan; Sonneborn, George; Srinivasan, Sundar; van Loon, Jacco Th.; Zijlstra, Albert; Sloan, Greg

    2016-08-01

    The origin of dust in the early Universe is a matter of debate. One of the main potential dust contributors are Asymptotic Giant Branch (AGB) stars, and several studies have been devoted to investigating whether and how AGB dust production changes in metal-poor environments. Of particular interest are the most massive AGB stars (8-10 Msun), which can in principle enter the dust-producing phase <50 Myr after they form. However, these stars cannot produce their own condensable material (unlike carbon AGB stars), so the efficiency of dust production decreases with metallicity. Evidence for dust production in massive AGB stars more metal-poor than the Magellanic Clouds is scarce due both to the rarity of chemically-unevolved, star-forming systems reachable in the infrared and to the short lifetimes of these stars. The recently discovered galaxy Leo P provides an irresistible opportunity to search for these massive AGB stars: Leo P is a gas-rich, star-forming galaxy, it is nearby enough for resolved star photometry with Spitzer, and its interstellar medium is 0.4 dex more metal-poor than any other accessible star-forming galaxy. Models predict ~3 massive AGB stars may be present in Leo P, and optical HST observations reveal 7 candidates. We propose to use Spitzer to determine whether these stars are dusty, providing valuable constraints to the dust contribution from AGB stars up to at least redshift 3.2, or 11.7 Gyr ago, when massive spheroidals and Galactic globular clusters were still forming. This is a gain of 2.8 Gyr compared to other accessible galaxies. We also request 1 orbit of joint HST time to confirm whether the AGB candidates in Leo P are indeed massive AGB stars belonging to the galaxy. These observations will provide information crucial for potential JWST followup spectroscopy.

  12. HUBBLE SPACE TELESCOPE Observations of the Local Group Dwarf Galaxy Leo I

    NASA Astrophysics Data System (ADS)

    Gallart, Carme; Freedman, Wendy L.; Mateo, Mario; Chiosi, Cesare; Thompson, Ian B.; Aparicio, Antonio; Bertelli, Gianpaolo; Hodge, Paul W.; Lee, Myung G.; Olszewski, Edward W.; Saha, Abhijit; Stetson, Peter B.; Suntzeff, Nicholas B.

    1999-04-01

    We present deep HST F555W (V) and F814W (I) observations of a central field in the Local Group dwarf spheroidal (dSph) galaxy Leo I. The resulting color-magnitude diagram (CMD) reaches I~=26 and reveals the oldest ~=10-15 Gyr old turnoffs. Nevertheless, a horizontal branch is not obvious in the CMD. Given the low metallicity of the galaxy, this likely indicates that the first substantial star formation in the galaxy may have been somehow delayed in Leo I in comparison with the other dSph satellites of the Milky Way. The subgiant region is well and uniformly populated from the oldest turnoffs up to the 1 Gyr old turnoff, indicating that star formation has proceeded in a continuous way, with possible variations in intensity but no big gaps between successive bursts, over the galaxy's lifetime. The structure of the red clump of core He-burning stars is consistent with the large amount of intermediate-age population inferred from the main sequence and the subgiant region. In spite of the lack of gas in Leo I, the CMD clearly shows star formation continuing until 1 Gyr ago and possibly until a few hundred Myr ago in the central part of the galaxy.

  13. Controlling the Growth of Future LEO Debris Populations with Active Debris Removal

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.; Johnson, N. L.; Hill, N. M.

    2008-01-01

    Active debris removal (ADR) was suggested as a potential means to remediate the low Earth orbit (LEO) debris environment as early as the 1980s. The reasons ADR has not become practical are due to its technical difficulties and the high cost associated with the approach. However, as the LEO debris populations continue to increase, ADR may be the only option to preserve the near-Earth environment for future generations. An initial study was completed in 2007 to demonstrate that a simple ADR target selection criterion could be developed to reduce the future debris population growth. The present paper summarizes a comprehensive study based on more realistic simulation scenarios, including fragments generated from the 2007 Fengyun-1C event, mitigation measures, and other target selection options. The simulations were based on the NASA long-term orbital debris projection model, LEGEND. A scenario, where at the end of mission lifetimes, spacecraft and upper stages were moved to 25-year decay orbits, was adopted as the baseline environment for comparison. Different annual removal rates and different ADR target selection criteria were tested, and the resulting 200-year future environment projections were compared with the baseline scenario. Results of this parametric study indicate that (1) an effective removal strategy can be developed based on the mass and collision probability of each object as the selection criterion, and (2) the LEO environment can be stabilized in the next 200 years with an ADR removal rate of five objects per year.

  14. Phylogeographic Patterns in Africa and High Resolution Delineation of Genetic Clades in the Lion (Panthera leo)

    NASA Astrophysics Data System (ADS)

    Bertola, L. D.; Jongbloed, H.; van der Gaag, K. J.; de Knijff, P.; Yamaguchi, N.; Hooghiemstra, H.; Bauer, H.; Henschel, P.; White, P. A.; Driscoll, C. A.; Tende, T.; Ottosson, U.; Saidu, Y.; Vrieling, K.; de Iongh, H. H.

    2016-08-01

    Comparative phylogeography of African savannah mammals shows a congruent pattern in which populations in West/Central Africa are distinct from populations in East/Southern Africa. However, for the lion, all African populations are currently classified as a single subspecies (Panthera leo leo), while the only remaining population in Asia is considered to be distinct (Panthera leo persica). This distinction is disputed both by morphological and genetic data. In this study we introduce the lion as a model for African phylogeography. Analyses of mtDNA sequences reveal six supported clades and a strongly supported ancestral dichotomy with northern populations (West Africa, Central Africa, North Africa/Asia) on one branch, and southern populations (North East Africa, East/Southern Africa and South West Africa) on the other. We review taxonomies and phylogenies of other large savannah mammals, illustrating that similar clades are found in other species. The described phylogeographic pattern is considered in relation to large scale environmental changes in Africa over the past 300,000 years, attributable to climate. Refugial areas, predicted by climate envelope models, further confirm the observed pattern. We support the revision of current lion taxonomy, as recognition of a northern and a southern subspecies is more parsimonious with the evolutionary history of the lion.

  15. Optimal planning of LEO active debris removal based on hybrid optimal control theory

    NASA Astrophysics Data System (ADS)

    Yu, Jing; Chen, Xiao-qian; Chen, Li-hu

    2015-06-01

    The mission planning of Low Earth Orbit (LEO) active debris removal problem is studied in this paper. Specifically, the Servicing Spacecraft (SSc) and several debris exist on near-circular near-coplanar LEOs. The SSc should repeatedly rendezvous with the debris, and de-orbit them until all debris are removed. Considering the long-duration effect of J2 perturbation, a linear dynamics model is used for each rendezvous. The purpose of this paper is to find the optimal service sequence and rendezvous path with minimum total rendezvous cost (Δv) for the whole mission, and some complex constraints (communication time window constraint, terminal state constraint, and time distribution constraint) should be satisfied meanwhile. Considering this mission as a hybrid optimal control problem, a mathematical model is proposed, as well as the solution method. The proposed approach is demonstrated by a typical active debris removal problem. Numerical experiments show that (1) the model and solution method proposed in this paper can effectively address the planning problem of LEO debris removal; (2) the communication time window constraint and the J2 perturbation have considerable influences on the optimization results; and (3) under the same configuration, some suboptimal sequences are equivalent to the optimal one since their difference in Δv cost is very small.

  16. Phylogeographic Patterns in Africa and High Resolution Delineation of Genetic Clades in the Lion (Panthera leo)

    PubMed Central

    Bertola, L. D.; Jongbloed, H.; van der Gaag, K. J.; de Knijff, P.; Yamaguchi, N.; Hooghiemstra, H.; Bauer, H.; Henschel, P.; White, P. A.; Driscoll, C. A.; Tende, T.; Ottosson, U.; Saidu, Y.; Vrieling, K.; de Iongh, H. H.

    2016-01-01

    Comparative phylogeography of African savannah mammals shows a congruent pattern in which populations in West/Central Africa are distinct from populations in East/Southern Africa. However, for the lion, all African populations are currently classified as a single subspecies (Panthera leo leo), while the only remaining population in Asia is considered to be distinct (Panthera leo persica). This distinction is disputed both by morphological and genetic data. In this study we introduce the lion as a model for African phylogeography. Analyses of mtDNA sequences reveal six supported clades and a strongly supported ancestral dichotomy with northern populations (West Africa, Central Africa, North Africa/Asia) on one branch, and southern populations (North East Africa, East/Southern Africa and South West Africa) on the other. We review taxonomies and phylogenies of other large savannah mammals, illustrating that similar clades are found in other species. The described phylogeographic pattern is considered in relation to large scale environmental changes in Africa over the past 300,000 years, attributable to climate. Refugial areas, predicted by climate envelope models, further confirm the observed pattern. We support the revision of current lion taxonomy, as recognition of a northern and a southern subspecies is more parsimonious with the evolutionary history of the lion. PMID:27488946

  17. Design application and development of spacecraft in LEO utilizing LDEF results

    NASA Technical Reports Server (NTRS)

    Rauch, George B., Jr.; Sudduth, Richard D.

    1993-01-01

    In general, the results from the Long Duration Exposure Facility (LDEF) have provided much useful information on material sensitivity in the low-Earth orbit (LEO) environment. This is particularly true for selected materials such as thermal control coatings, composites, polymers, fasteners and solar cells. However, LDEF material sensitivity data for other materials like glasses, glass coatings, lubricants, adhesives and seal materials were limited. Some of this important LDEF material sensitivity data has not yet been addressed in detail at the LDEF meetings. The type of material information needed in the design and development of a new spacecraft in LEO depends to a large extent on program phase. In early program phases it is only necessary to have material sensitivity data to determine what materials may or may not work. Later program phases require details on the material strength, optical properties, and/or other long term survivability requirements for materials in LEO. Unfortunately, documentation of exposure results for many materials sensitivity experiments that flew on LDEF has not yet been summarized in a convenient form for use by multiple users. Documentation of this data in a form convenient for scientists, engineers as well as technicians remains a significant area of concern for the aerospace industry. Many of the material experiments that flew on LDEF were only designed to measure material sensitivity for one year in an LEO environment. However, some materials expected to survive one year simply did not survive the 5.8 years that LDEF eventually remained in orbit. Therefore the survivability of several materials in an LEO environment was determined by default. Most of the LDEF materials experiments were not designed to establish long term material survivability data. This long term material survivability data is particularly useful in later program phases of spacecraft development. The lack of more controlled materials experiments to determine long

  18. Two-manoeuvres transfers between LEOs and Lissajous orbits in the Earth-Moon system

    NASA Astrophysics Data System (ADS)

    Alessi, Elisa Maria; Gómez, Gerard; Masdemont, Josep J.

    2010-05-01

    The purpose of this work is to compute transfer trajectories from a given Low Earth Orbit (LEO) to a nominal Lissajous quasi-periodic orbit either around the point L1 or the point L2 in the Earth-Moon system. This is achieved by adopting the Circular Restricted Three-Body Problem (CR3BP) as force model and applying the tools of Dynamical Systems Theory. It is known that the CR3BP admits five equilibrium points, also called Lagrangian points, and a first integral of motion, the Jacobi integral. In the neighbourhood of the equilibrium points L1 and L2, there exist periodic and quasi-periodic orbits and hyperbolic invariant manifolds which emanate from them. In this work, we focus on quasi-periodic Lissajous orbits and on the corresponding stable invariant manifolds. The transfers under study are established on two manoeuvres: the first one is required to leave the LEO, the second one to get either into the Lissajous orbit or into its associated stable manifold. We exploit order 25 Lindstedt-Poincaré series expansions to compute invariant objects, classical manoeuvres and differential correction procedures to build the whole transfer. If part of the trajectory lays on the stable manifold, it turns out that the transfer’s total cost, Δv, and time, t, depend mainly on: the altitude of the LEO;the geometry of the arrival orbit;the point of insertion into the stable manifold;the angle between the velocity of insertion on the manifold and the velocity on it. As example, for LEOs 360 km high and Lissajous orbits of about 6000 km wide, we obtain Δv∈[3.68,4.42]km/sandt∈[5,40]days. As further finding, when the amplitude of the target orbit is large enough, there exist points for which it is more convenient to transfer from the LEO directly to the Lissajous orbit, that is, without inserting into its stable invariant manifold.

  19. Effect of KOH concentration on LEO cycle life of IPV nickel-hydrogen flight cells-update 2

    NASA Technical Reports Server (NTRS)

    Smithrick, John J.; Hall, Stephen W.

    1991-01-01

    An update of validation test results confirming the breakthrough in low earth orbit (LEO) cycle life of nickel-hydrogen cells containing 26 percent KOH electrolyte is presented. A breakthrough in the LEO cycle life of individual pressure vessel (IPV nickel-hydrogen cells has been previously reported. The cycle life of boiler plate cells containing 26 percent potassium hydroxide (KOH) electrolyte was about 40 000 LEO cycles compared to 3500 cycles for cells containing 31 percent KOH. This test was conducted at Hughes Aircraft Company under a NASA Lewis contract. The purpose was to investigate the effect of KOH concentration on cycle life. The cycle regime was a stressful accelerated LEO, which consisted of a 27.5 min charge followed by a 17.5 min discharge (2x normal rate). The depth of discharge (DOD) was 80 percent. The cell temperature was maintained at 23 C. The boiler plate test results are in the process of being validated using flight hardware and real time LEO test at the Naval Weapons Support Center (NWSC), Crane, Indiana under a NASA Lewis Contract. Six 48 Ah Hughes recirculation design IPV nickel-hydrogen flight battery cells are being evaluated. Three of the cells contain 26 percent KOH (test cells), and three contain 31 percent KOH (control cells). They are undergoing real time LEO cycle life testing. The cycle regime is a 90-min LEO orbit consisting of a 54-min charge followed by a 36-min discharge. The depth-of-discharge is 80 percent. The cell temperature is maintained at 10 C. The three 31 percent KOH cells failed (cycles 3729, 4165, and 11355). One of the 26 percent KOH cells failed at cycle 15314. The other two 26 percent KOH cells were cycled for over 16600 cycles during the continuing test.

  20. Investigation on aerosol optical properties over East Asia: From LEO to GEO satellites

    NASA Astrophysics Data System (ADS)

    Song, C. H.; Park, M.; Park, R.; Lee, J.; Lee, K.; Lee, S.; Kim, J.

    2011-12-01

    Aerosol optical properties (AOP) have been regarded as good proxy indicators of the levels of particulate air pollutants such as PM2.5 and PM10, and have also been widely used for estimating direct radiative forcing (DRF) by aerosols. Up to date, the AOP have been retrieved mainly from the Low Earth Orbit (LEO) satellites such as terra- and aqua-MODIS. However, the critical limitation of the AOP products from the LEO satellites is relatively long temporal resolution of one to several days. In order to overcome this critical limitation, the Geostationary Earth Orbit (GEO) satellite-retrieved data is begun to be used recently. Therefore, in this study, several topics related to the fore-mentioned issues are introduced: (i) current status of the AOP retrieval from the LEO satellites and the AOP calculations from chemistry-transfer model (CTM) simulations over East Asia; (ii) the uses of the AOP data for estimating particulate pollution and DRF by aerosols in East Asia; (iii) preliminary AOP data retrieved from a geostationary sensor (GOCI: Geostationary Ocean Color Imager) on a Korean GEO satellite (COMS: Communication Ocean Meteorology Satellite); and (iv) possible improvements of the GEO-retrieved AOP data, combining them with the AOP data calculated from the CTM simulations over East Asia via a data assimilation technique. Regarding the AOP data retrievals from the COMS-GOCI sensor, two Korean aerosol retrieval algorithms are also introduced briefly: (i) Yonsei algorithm and (ii) GSTAR (GIST Aerosol Retrieval) algorithm. It is also discussed that these researches are being carried out with long-term research goals, aiming at the future applications of the AOP data, which is expected to be available from the world-first Korean environmental GEO sensors (GEMS: Geostationary Environmental Monitoring Sensor and GOCI-2) scheduled to be launched in 2017 or 2018, to the investigations onto the particulate air pollution and the DRF estimation by aerosols over East Asia (as

  1. Satellite co-locations as a link between SLR, GPS and Low Earth Orbiting (LEO) satellites

    NASA Astrophysics Data System (ADS)

    Melachroinos, S. A.; Lemoine, F. G.; Chinn, D. S.; Nicolas, J. B.; Zelensky, N. P.; Wimert, J.; Radway, Y.

    2013-12-01

    The procedure applied for the determination of the International Terrestrial Reference Frame (ITRF) requires the combination of all four major techniques of Space Geodesy. This combination is only possibly realized by the introduction of the local-ties between co-located techniques. A local-tie is the lever arm vector between the marker points on the sites where two or more space geodesy instruments operate. The local ties are used as additional observations with proper variances. They are usually derived from local surveys using either classical geodesy or the global navigation satellite systems (GNSS). The Global Positioning System (GPS) plays a major role in the ITRF combination by linking together all the other three techniques SLR, DORIS and VLBI (Altamimi and Collilieux 2009). However, discrepancies between local ties and space geodesy estimates are well known although the reasons for these discrepancies are often not clear. These discrepancies could be either due to errors in local ties and in coordinate estimates or in both. In this study, we use the tracking to G05-35 and G06-36 and one LEO by SLR sites and their combined orbits, earth rotation parameters (ERPs) and station positions in order to establish space-based co-location ties on the stations. The LEO satellite used in this experiment is Jason-2, which carries both GPS and SLR. Therefore from the data-processing point of view the LEO satellite is used as a fast moving station (Thaller et al. 2011). Jason-2 is also equipped with DORIS, but it will be included into another combined analysis. Subsequently, we compare the consistency of our space-based co-locations to the ones from ITRF08 and SLRF08 - IGb08 solutions.

  2. HERRO: A Science-Oriented Strategy for Crewed Missions Beyond LEO

    NASA Technical Reports Server (NTRS)

    Schmidt, George R.

    2011-01-01

    This paper presents an exploration strategy for human missions beyond Low Earth Orbit (LEO) and the Moon that combines the best features of human and robotic spaceflight. This "Human Exploration using Real-time Robotic Operations" (HERRO) strategy refrains from placing humans on the surfaces of the Moon and Mars in the near-term. Rather, it focuses on sending piloted spacecraft and crews into orbit around exploration targets of interest, such as Mars, and conducting astronaut exploration of the surfaces using telerobots and remotely controlled systems. By eliminating the significant communications delay with Earth due to the speed of light limit, teleoperation provides scientists real-time control of rovers and other sophisticated instruments, in effect giving them a "virtual presence" on planetary surfaces, and thus expanding the scientific return at these destinations. It also eliminates development of the numerous man-rated landers, ascent vehicles and surface systems that are required to land humans on planetary surfaces. The propulsive requirements to travel from LEO to many destinations with shallow gravity-wells in the inner solar system are quite similar. Thus, a single spacecraft design could perform a variety of missions, including orbit-based surface exploration of the Moon, Mars and Venus, and rendezvous with Near Earth Asteroids (NEAs), as well as Phobos and Deimos. Although HERRO bypasses many of the initial steps that have been historically associated with human space exploration, it opens the door to many new destinations that are candidates for future resource utilization and settlement. HERRO is a first step that takes humans to exciting destinations beyond LEO, while expanding the ability to conduct science within the inner solar system.

  3. Measurements of Multi-star Systems LEO 5 and MKT 13

    NASA Astrophysics Data System (ADS)

    AlZaben, Faisal; Priest, Allen; Priest, Stephen; Qiu, Rex; Boyce, Grady; Boyce, Pat

    2016-04-01

    We report measurements of the position angles and separations of two multi-star systems observed during the fall of 2015. Image data was obtained using an online 17-inch iTelescope system in Nerpio, Spain. Image data was analyzed using Maxim DL Pro 6 and Mira Pro x64 software tools at the Army and Navy Academy in Carlsbad, California. Our measurements of the LEO 5 system are consistent with historical data, although inconclusive as to the nature of the system. Our measurements and the historical data for the MKT 13 system show a consistent linearity in the position angle and separation.

  4. Low-Earth-Orbit (LEO) Life Cycle Evaluation of Nickel-Zinc Batteries

    NASA Technical Reports Server (NTRS)

    Coates, D.; Ferreira, E.; Nyce, M.; Charkey, A.

    1997-01-01

    The conclusion of the Low-Earth-Orbit (LEO) life cycle evaluation of nickel-zinc batteries are: that composite nickel electrode provide excellent performance at a reduced weight and lower cost; calcium / zinc electrode minimizes shape change; unioptimized cell designs yield 60 Wh/kg; nickel-zinc delivers 600 cycles at 80% DOD; long cycle life obtainable at low DOD; high rate capability power density; long-term failure mechanism is stack dry; and anomalous overcharge (1120%) greatly affected cell performance but did not induce failure and was recoverable.

  5. Re-Entry Point Targeting for LEO Spacecraft using Aerodynamic Drag

    NASA Technical Reports Server (NTRS)

    Omar, Sanny; Bevilacqua, Riccardo; Fineberg, Laurence; Treptow, Justin; Johnson, Yusef; Clark, Scott

    2016-01-01

    Most Low Earth Orbit (LEO) spacecraft do not have thrusters and re-enter atmosphere in random locations at uncertain times. Objects pose a risk to persons, property, or other satellites. Has become a larger concern with the recent increase in small satellites. Working on a NASA funded project to design a retractable drag device to expedite de-orbit and target a re-entry location through modulation of the drag area. Will be discussing the re-entry point targeting algorithm here.

  6. [The situational diagnosis of the medical units of Petróleos Mexicanos].

    PubMed

    García-Romero, H; Cordera-Pastor, A; Vargas-Martínez, J

    1993-01-01

    The Medical Service Management of Petróleos Mexicanos developed a situational diagnosis of 30 medical units in 1992. This evaluation covered 94 per cent of the institutional population. The basis for this evaluation was a formulary with more than 70 per cent closed questions and instructions with explicit explanations about them. The main points that the formulary investigated were: geography, demography, sociocultural and economics aspects, epidemiology, morbidity, mortality, preventive medicine, service availability and others. With this situational diagnosis we have been able to identify the main problems with a possible solution, presented in terms of planning, organization and execution of actions.

  7. On the feasibility of phase only PPP for kinematic LEO orbits

    NASA Astrophysics Data System (ADS)

    Wallat, Christoph; Schön, Steffen

    2016-04-01

    Low Earth Orbiters (LEO) are satellites in altitudes up to 1000 kilometers. From the sensor data collected on board the Earth's gravity field can be recovered. Over the last 15 years several satellite missions were brought into space and the orbit determination improved over the years. To process the sensor data, precise positioning and timing of the satellite is mandatory. There are two approaches for precise orbit determination (POD) of LEO satellites. Kinematic orbits are based on GNSS observations and star camera data measured on board of the LEO. With a Precise Point Positioning (PPP) known from the terrestrial case, using ionospheric-free linear combinations P3 and L3 three-dimensional coordinates of the LEO can be estimated for every observation epoch. To counteract the challenges in kinematic orbit determination our approach is based on a technique called GNSS receiver clock modeling (RCM). Here the frequency stability of an external oscillator is used to model the behavior of the GNSS receiver clock with piecewise linear polynomials instead of estimating epoch-wise the receiver clock time offset as an unknown parameter. When using RCM the observation geometry is stabilized and the orbit coordinates and the receiver clock error can be estimated with a better precision. The satellites of the Gravity Recovery And Climate Experiment (GRACE) mission are equipped with Ultra Stable quartz Oscillators (USO). The USO frequency stability is used to correct the GRACE GPS receiver clock. Therefore, receiver clock modeling is feasible for polynomials with a length up to 60 seconds, leading to improved mean PDOP values of 30 % and smaller formal mean standard deviations of the coordinates between 6 and 33 %. We developed a new approach for GRACE orbits using kinematic PPP with clock modeling and tested our approach with simulated and real GPS data. The idea to use only carrier phase observations in the final processing and no code measurements leads to a reduced number

  8. Commentary: Science, Technology, and Society in Guidelines for Using Technology to Prepare Social Studies Teachers--A Reply to Hicks et al. and Crocco and Leo

    ERIC Educational Resources Information Center

    Mason, Lance

    2015-01-01

    This essay is a response to both the "Guidelines for Using Technology to Prepare Social Studies Teachers" published in this journal by Hicks, Lee, Berson, Bolick, and Diem (2014) and the rejoinder by Crocco and Leo (2015). The author agrees with Crocco and Leo's assessment that removing the principal regarding science, technology, and…

  9. High intensity 5 eV atomic oxygen source and Low Earth Orbit (LEO) simulation facility

    NASA Technical Reports Server (NTRS)

    Cross, J. B.; Spangler, L. H.; Hoffbauer, M. A.; Archuleta, F. A.; Leger, Lubert; Visentine, James

    1987-01-01

    An atomic oxygen exposure facility has been developed for studies of material degradation. The goal of these studies is to provide design criteria and information for the manufacture of long life (20 to 30 years) construction materials for use in LEO. The studies that are being undertaken using the facility will provide: absolute reaction cross sections for use in engineering design problems; formulations of reaction mechanisms; and calibration of flight hardware (mass spectrometers, etc.) in order to directly relate experiments performed in LEO to ground based investigations. The facility consists of: (1) a CW laser sustained discharge source of O atoms having a variable energy up to 5 eV and an intensity between 10(15) and 10(17) O atoms s(-1) cm(-2); (2) an atomic beam formation and diagnostics system consisting of various stages of differential pumping, a mass spectrometer detector, and a time of flight analyzer; (3) a spinning rotor viscometer for absolute O atom flux measurements; and (4) provision for using the system for calibration of actual flight instruments. Surface analysis equipment is available for the characterization of material surfaces before and after exposure to O atoms.

  10. A Parametric Study on Using Active Debris Removal to Stabilize the Future LEO Debris Environment

    NASA Technical Reports Server (NTRS)

    Liou, J.C.

    2010-01-01

    Recent analyses of the instability of the orbital debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have reignited the interest in using active debris removal (ADR) to remediate the environment. There are; however, monumental technical, resources, operational, legal, and political challenges in making economically viable ADR a reality. Before a consensus on the need for ADR can be reached, a careful analysis of the effectiveness of ADR must be conducted. The goal is to demonstrate the feasibility of using ADR to preserve the future environment and to guide its implementation to maximize the benefit-cost ratio. This paper describes a comprehensive sensitivity study on using ADR to stabilize the future LEO debris environment. The NASA long-term, orbital debris evolutionary model, LEGEND, is used to quantify the effects of many key parameters. These parameters include (1) the starting epoch of ADR implementation, (2) various target selection criteria, (3) the benefits of collision avoidance maneuvers, (4) the consequence of targeting specific inclination or altitude regimes, (5) the consequence of targeting specific classes of vehicles, and (6) the timescale of removal. Additional analyses on the importance of postmission disposal and how future launches might affect the requirements to stabilize the environment are also included.

  11. A Parametric Study on Using Active Debris Removal for LEO Environment Remediation

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Recent analyses on the instability of the orbital debris population in the low Earth orbit (LEO) region and the collision between Iridium 33 and Cosmos 2251 have reignited the interest in using active debris removal (ADR) to remediate the environment. There are; however, monumental technical, resource, operational, legal, and political challenges in making economically viable ADR a reality. Before a consensus on the need for ADR can be reached, a careful analysis of its effectiveness must be conducted. The goal is to demonstrate the need and feasibility of using ADR to better preserve the future environment and to guide its implementation to maximize the benefit-to-cost ratio. This paper describes a new sensitivity study on using ADR to stabilize the future LEO debris environment. The NASA long-term orbital debris evolutionary model, LEGEND, is used to quantify the effects of several key parameters, including target selection criteria/constraints and the starting epoch of ADR implementation. Additional analyses on potential ADR targets among the currently existing satellites and the benefits of collision avoidance maneuvers are also included.

  12. Nickel-hydrogen LEO cycling at 20-50 percent DOD. [depth of discharge

    NASA Technical Reports Server (NTRS)

    Lowery, John E.; Mai, Jenny

    1991-01-01

    Two NiH2 two-cell packs made up of engineering cells built according to the Hubble Space Telescope design (EPI RNH 90-3) are currently being low-earth-orbit (LEO) cycled at 20-50 percent depth of discharge (DOD). The cells were manufactured by Eagle-Picher Industries, Inc., and activated with electrolyte (KOH) concentrations of 26 percent (pack No.1) and 31 percent (pack No.2), for use during evaluation of the HST cell design. The cells have been grouped according to electrolyte concentration but follow the same test schedule for comparison. This test was set up to study the behavior of NiH2 cells having differing electrolyte concentrations, when operated at relatively high DOD (20-50 percent) in a LEO cycling program. The test was designed specifically to allow the cells to pick their own recharge ratio for varying DOD and varying EOC (end of charge) voltages. The cells are being cycled in a simulated 96-min orbit with 60-min charge and 36-min discharge where an EOC cutoff voltage controls high-rate charging. EOC cutoff voltages vary between 1.48 V and 1.56 V.

  13. Microbiological monitoring and automated event sampling at karst springs using LEO-satellites.

    PubMed

    Stadler, H; Skritek, P; Sommer, R; Mach, R L; Zerobin, W; Farnleitner, A H

    2008-01-01

    Data communication via Low-Earth-Orbit (LEO) Satellites between portable hydrometeorological measuring stations is the backbone of our system. This networking allows automated event sampling with short time increments also for E. coli field analysis. All activities of the course of the event-sampling can be observed on an internet platform based on a Linux-Server. Conventionally taken samples compared with the auto-sampling procedure revealed corresponding results and were in agreement with the ISO 9308-1 reference method. E. coli concentrations were individually corrected by event specific inactivation coefficients (0.10-0.14 day(-1)), compensating losses due to sample storage at spring temperature in the auto sampler.Two large summer events in 2005/2006 at an important alpine karst spring (LKAS2) were monitored including detailed analysis of E. coli dynamics (n = 271) together with comprehensive hydrological characterisations. High-resolution time series demonstrated a sudden increase of E. coli concentrations in spring water (approximately 2 log10 units) with a specific time delay after the beginning of the event. Statistical analysis suggested the spectral absorption coefficient measured at 254 nm (SAC254) as an early warning surrogate for real time monitoring of faecal input. Together with the LEO-satellite based system it is a helpful tool for early-warning systems in the field of drinking water protection.

  14. A Multi-epoch Kinematic Study of the Remote Dwarf Spheroidal Galaxy Leo II

    NASA Astrophysics Data System (ADS)

    Spencer, Meghin E.; Mateo, Mario; Walker, Matthew G.; Olszewski, Edward W.

    2017-02-01

    We conducted a large spectroscopic survey of 336 red giants in the direction of the Leo II dwarf galaxy using Hectochelle on the Multiple Mirror Telescope, and we conclude that 175 of them are members based on their radial velocities and surface gravities. Of this set, 40 stars have never before been observed spectroscopically. The systemic velocity of the dwarf is 78.3 ± 0.6 km s‑1 with a velocity dispersion of 7.4 ± 0.4 km s‑1. We identify one star beyond the tidal radius of Leo II but find no signatures of uniform rotation, kinematic asymmetries, or streams. The stars show a strong metallicity gradient of ‑1.53 ± 0.10 dex kpc‑1 and have a mean metallicity of ‑1.70 ± 0.02 dex. There is also evidence of two different chemodynamic populations, but the signal is weak. A larger sample of stars would be necessary to verify this feature. Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution.

  15. Minimum Number of Observation Points for LEO Satellite Orbit Estimation by OWL Network

    NASA Astrophysics Data System (ADS)

    Park, Maru; Jo, Jung Hyun; Cho, Sungki; Choi, Jin; Kim, Chun-Hwey; Park, Jang-Hyun; Yim, Hong-Suh; Choi, Young-Jun; Moon, Hong-Kyu; Bae, Young-Ho; Park, Sun-Youp; Kim, Ji-Hye; Roh, Dong-Goo; Jang, Hyun-Jung; Park, Young-Sik; Jeong, Min-Ji

    2015-12-01

    By using the Optical Wide-field Patrol (OWL) network developed by the Korea Astronomy and Space Science Institute (KASI) we generated the right ascension and declination angle data from optical observation of Low Earth Orbit (LEO) satellites. We performed an analysis to verify the optimum number of observations needed per arc for successful estimation of orbit. The currently functioning OWL observatories are located in Daejeon (South Korea), Songino (Mongolia), and Oukaïmeden (Morocco). The Daejeon Observatory is functioning as a test bed. In this study, the observed targets were Gravity Probe B, COSMOS 1455, COSMOS 1726, COSMOS 2428, SEASAT 1, ATV-5, and CryoSat-2 (all in LEO). These satellites were observed from the test bed and the Songino Observatory of the OWL network during 21 nights in 2014 and 2015. After we estimated the orbit from systematically selected sets of observation points (20, 50, 100, and 150) for each pass, we compared the difference between the orbit estimates for each case, and the Two Line Element set (TLE) from the Joint Space Operation Center (JSpOC). Then, we determined the average of the difference and selected the optimal observation points by comparing the average values.

  16. Space environmental effects on spacecraft: LEO materials selection guide, part 1

    NASA Technical Reports Server (NTRS)

    Silverman, Edward M.

    1995-01-01

    This document provides performance properties on major spacecraft materials and subsystems that have been exposed to the low-Earth orbit (LEO) space environment. Spacecraft materials include metals, polymers, composites, white and black paints, thermal-control blankets, adhesives, and lubricants. Spacecraft subsystems include optical components, solar cells, and electronics. Information has been compiled from LEO short-term spaceflight experiments (e.g., space shuttle) and from retrieved satellites of longer mission durations (e.g., Long Duration Exposure Facility). Major space environment effects include atomic oxygen (AO), ultraviolet radiation, micrometeoroids and debris, contamination, and particle radiation. The main objective of this document is to provide a decision tool to designers for designing spacecraft and structures. This document identifies the space environments that will affect the performance of materials and components, e.g., thermal-optical property changes of paints due to UV exposures, AO-induced surface erosion of composites, dimensional changes due to thermal cycling, vacuum-induced moisture outgassing, and surface optical changes due to AO/UV exposures. Where appropriate, relationships between the space environment and the attendant material/system effects are identified. Part 1 covers spacecraft design considerations for the space environment; advanced composites; polymers; adhesives; metals; ceramics; protective coatings; and lubricants, greases, and seals.

  17. The Komplast Experiment: Space Environmental Effects after 12 Years in LEO (and Counting)

    NASA Technical Reports Server (NTRS)

    Shaevich, Sergei K.; Aleksandrov, Nicholai G.; Shumov, Andrei E.; Novikov, L. S.; Alred, John A.; Shindo, David J.; Kravchenko, Michael; Golden, Johnny L.

    2014-01-01

    The Komplast materials experiment was designed by the Khrunichev Space Center, together with other Russian scientific institutes, and has been carried out by Mission Control Moscow since 1998. The purpose is to study the effect of the low earth orbit (LEO) environment on exposed samples of various spacecraft materials. The Komplast experiment began with the launch of the first International Space Station (ISS) module on November 20, 1998. Two of eight experiment panels were retrieved during Russian extravehicular activity in February 2011 after 12 years of LEO exposure, and were subsequently returned to Earth by Space Shuttle "Discovery" on the STS-133/ULF-5 mission. The retrieved panels contained an experiment to detect micrometeoroid and orbital debris (MMOD) impacts, radiation sensors, a temperature sensor, several pieces of electrical cable, both carbon composite and adhesive-bonded samples, and many samples made from elastomeric and fluoroplastic materials. Our investigation is complete and a summary of the results obtained from this uniquely long-duration exposure experiment will be presented.

  18. Observation angle and plane characterisation for ISAR imaging of LEO space objects

    NASA Astrophysics Data System (ADS)

    Chen, Jin; Fu, Tuo; Chen, Defeng; Gao, Meiguo

    2016-07-01

    For inverse synthetic aperture radar (ISAR) imaging of low Earth orbit (LEO) space objects, examining the variations in the image plane of the object over the entire visible arc period allows more direct characterisation of the variations in the object imaging. In this study, the ideal turntable model was extended to determine the observation geometry of near-circular LEO objects. Two approximations were applied to the observation model to calculate the image plane's normal and observation angles for near-circular orbit objects. One approximation treats the orbit of the space object as a standard arc relative to the Earth during the radar observation period, and the other omits the effect of the rotation of the Earth on the observations. First, the closed-form solution of the image plane normal in various attitude-stabilisation approaches was determined based on geometric models. The characteristics of the image plane and the observation angle of the near-circular orbit object were then analysed based on the common constraints of the radar line-of-sight (LOS). Subsequently, the variations in the image plane and the geometric constraints of the ISAR imaging were quantified. Based on the image plane's normal, the rotational angular velocity of the radar LOS was estimated. The cross-range direction of the ISAR image was then calibrated. Three-dimensional imaging was then reconstructed based on dual station interferometry. Finally, simulations were performed to verify the result of the three-dimensional interferometric reconstruction and to calculate the reconstruction's precision errors.

  19. Space environmental effects on spacecraft: LEO materials selection guide, part 2

    NASA Technical Reports Server (NTRS)

    Silverman, Edward M.

    1995-01-01

    This document provides performance properties on major spacecraft materials and subsystems that have been exposed to the low-Earth orbit (LEO) space environment. Spacecraft materials include metals, polymers, composites, white and black paints, thermal-control blankets, adhesives, and lubricants. Spacecraft subsystems include optical components, solar cells, and electronics. Information has been compiled from LEO short-term spaceflight experiments (e.g., space shuttle) and from retrieved satellites of longer mission durations (e.g., Long Duration Exposure Facility). Major space environment effects include atomic oxygen (AO), ultraviolet radiation, micrometeoroids and debris, contamination, and particle radiation. The main objective of this document is to provide a decision tool to designers for designing spacecraft and structures. This document identifies the space environments that will affect the performance of materials and components, e.g., thermal-optical property changes of paints due to UV exposures, AO-induced surface erosion of composites, dimensional changes due to thermal cycling, vacuum-induced moisture outgassing, and surface optical changes due to AO/UV exposures. Where appropriate, relationships between the space environment and the attendant material/system effects are identified. Part 2 covers thermal control systems, power systems, optical components, electronic systems, and applications.

  20. Evaluation of the night sky quality at El Leoncito and LEO++ in Argentina

    NASA Astrophysics Data System (ADS)

    Aubé, Martin; García, Beatriz; Fortin, Nicolas; Turcotte, Sara; Mancilla, Alexis; Maya, Javier

    2015-08-01

    Light pollution is a growing concern at many levels, but especially for the astronomical community. Artificial lighting veil celestial objects and disturbs the measurement of night time atmospheric phenomena. This is what motivates our sky brightness measurement experiment in Argentina. Our goal was to determine the quality of two Argentinian observation sites: LEO++ and El Leoncito. Both sites were candidates to host the Cherenkov Telescope Array (CTA). This project consists of an arrangement of many telescopes that can measure high-energy gamma ray emissions via their Cherenkov radiation produced when entering the earth's atmosphere. Even if the two argentinian sites has been excluded from the final CTA site competition, they are still of great interest for other astronomical projects. Especially the El Leoncito site which already hots the CASLEO astronomical complex. In this presentation, we describe the measurement methods used to determine the sky quality. We compared our results with different renowned astronomical sites (Kitt Peak, Arizona, USA, and Mont-Mégantic, Canada). Amongst our results, we found that LEO++ is a high quality site, however there are a lot of aerosols that can interfere with the measurements. El Leoncito shows very low sky brightness levels, which are optimal for low light level detection.

  1. Early Miocene granitoids from the Leo Pargil gneiss dome, northwest Himalaya

    NASA Astrophysics Data System (ADS)

    Hassett, W.; Leech, M. L.

    2007-12-01

    The Leo Pargil gneiss dome is comprised of upper amphibolite-facies metasedimentary rocks of the lower Tethyan Himalayan sequence (known as the Haimantas Group), that are intruded by numerous small granitoid bodies and leucogranite dikes. The dome is located in northern India/southwestern Tibet at the junction of the Sutlej and Spiti rivers, west of the Zada basin. U-Pb SHRIMP dating of zircon yield concordant ages ranging from Late Archean to Late Proterozoic for paragneisses (2.6 Ga to 970 Ma) corresponding to the Haimantas group, and Early Oligocene to Middle Miocene ages for granitoid intrusions (33 Ma to 15 Ma). Concordant analyses and lower intercept ages from Tera-Wasserburg concordia plots range from 28.1-17.2 Ma. Late Oligocene to Early Miocene ages are from zircon domains with consistently high U contents (1500 to over 25000 ppm). Linear regression of age vs. U content scatter plots show a trend toward younger ages (22-20 Ma) corresponding to ages from zircon with lower U contents (1000-3000 ppm) and that is consistent with lower intercept ages. These Early Miocene ages for Leo Pargil granitoids correspond to the ages for the widespread leucogranite bodies exposed throughout the Himalaya and granites from the North Himalayan gneiss domes further east.

  2. Data analysis and interpretation related to space system/environment interactions at LEO altitude

    NASA Technical Reports Server (NTRS)

    Raitt, W. John; Schunk, Robert W.

    1991-01-01

    Several studies made on the interaction of active systems with the LEO space environment experienced from orbital or suborbital platforms are covered. The issue of high voltage space interaction is covered by theoretical modeling studies of the interaction of charged solar cell arrays with the ionospheric plasma. The theoretical studies were complemented by experimental measurements made in a vacuum chamber. The other active system studied was the emission of effluent from a space platform. In one study the emission of plasma into the LEO environment was studied by using initially a 2-D model, and then extending this model to 3-D to correctly take account of plasma motion parallel to the geomagnetic field. The other effluent studies related to the releases of neutral gas from an orbiting platform. One model which was extended and used determined the density, velocity, and energy of both an effluent gas and the ambient upper atmospheric gases over a large volume around the platform. This model was adapted to study both ambient and contaminant distributions around smaller objects in the orbital frame of reference with scale sizes of 1 m. The other effluent studies related to the interaction of the released neutral gas with the ambient ionospheric plasma. An electrostatic model was used to help understand anomalously high plasma densities measured at times in the vicinity of the space shuttle orbiter.

  3. Preliminary Study of Geosynchronous Orbit Transfers from LEO using Invariant Manifolds

    NASA Astrophysics Data System (ADS)

    Davis, Kathryn E.; Anderson, Rodney L.; Born, George H.

    2011-07-01

    The invariant manifolds of libration point orbits (LPOs) in the Sun-Earth/Moon system are used to construct low-energy transfers from Low Earth Orbits (LEOs) to geosynchronous orbits. A maneuver is performed in LEO to insert onto a stable manifold trajectory of an LPO. The spacecraft travels to the host LPO and then follows an unstable manifold trajectory back to a geosynchronous orbit, where an orbit insertion maneuver is performed. The gravitational effects of the Sun-Earth/Moon three-body system act in such a way that large plane changes between the initial and final orbits at Earth may be realized without the execution of any plane change maneuvers. The maneuver costs of the transfers that employ invariant manifolds are compared to those using traditional techniques. The transfers that employ manifold trajectories can lower the cost of traditional Hohmann transfers by up to 3.15 km/s for transfers involving large differences in initial and final inclinations. The decrease in fuel expenditure is accompanied by an increase in time of flight; transfer durations are slightly over one year.

  4. DETECTION OF A GIANT EXTRASOLAR PLANET ORBITING THE ECLIPSING POLAR DP LEO

    SciTech Connect

    Qian, S.-B.; Liao, W.-P.; Zhu, L.-Y.; Dai, Z.-B.

    2010-01-01

    DP Leo is the first discovered eclipsing polar with a short period of 1.4967 hours. The period variation of the eclipsing binary was analyzed by using five new determined eclipse times together with those compiled from the literature. It is discovered that the O - C curve of DP Leo shows a cyclic variation with a period of 23.8 years and a semiamplitude of 31.5 s. The small-amplitude periodic change can be plausibly explained as the light-travel time effect due to the presence of a tertiary companion. The mass of the tertiary component is determined to be M {sub 3}sin i' = 0.00600({+-}0.00055) M {sub sun} = 6.28({+-}0.58) M {sub Jupiter} when a total mass of 0.69 M {sub sun} is adopted. If the tertiary companion is coplanar to the eclipsing binary (i.e., i' = 79.{sup 0}5), it should be a giant extrasolar planet with a mass of 6.39 M {sub Jupiter} at a distance of 8.6 astronomical units to the central binary. One of the most interesting things that we have learned about extrasolar planets over the last 17 years is that they can exist almost anywhere. The detection of a giant planet orbiting a polar would provide insight into the formation and evolution of circumbinary planets (planets orbiting both components of short-period binaries) as well as the late evolution of binary stars.

  5. Real-Time Optical Surveillance of LEO/MEO with Small Telescopes

    NASA Astrophysics Data System (ADS)

    Zimmer, P.; McGraw, J.; Ackermann, M.

    J.T. McGraw and Associates, LLC operates two proof-of-concept wide-field imaging systems to test novel techniques for uncued surveillance of LEO/MEO/GEO and, in collaboration with the University of New Mexico (UNM), uses a third small telescope for rapidly queued same-orbit follow-up observations. Using our GPU-accelerated detection scheme, the proof-of-concept systems operating at sites near and within Albuquerque, NM, have detected objects fainter than V=13 at greater than 6 sigma significance. This detection approximately corresponds to a 16 cm object with albedo of 0.12 at 1000 km altitude. Dozens of objects are measured during each operational twilight period, many of which have no corresponding catalog object. The two proof-of-concept systems, separated by ~30km, work together by taking simultaneous images of the same orbital volume to constrain the orbits of detected objects using parallax measurements. These detections are followed-up by imaging photometric observations taken at UNM to confirm and further constrain the initial orbit determination and independently assess the objects and verify the quality of the derived orbits. This work continues to demonstrate that scalable optical systems designed for real-time detection of fast moving objects, which can be then handed off to other instruments capable of tracking and characterizing them, can provide valuable real-time surveillance data at LEO and beyond, which substantively informs the SSA process.

  6. Resonant tunnelling diode oscillator as an alternative LO for SIS receiver applications

    NASA Technical Reports Server (NTRS)

    Blundell, R.; Papa, D. C.; Brown, E. R.; Parker, C. D.

    1993-01-01

    The resonant tunnelling diode (RTD) oscillator has been demonstrated for the first time as a local oscillator (LO) in a heterodyne receiver. Noise measurements made on a sensitive 200 GHz superconductor-insulator-superconductor receiver using both a multiplied Gunn diode and an RTD oscillator as the LO revealed no difference in receiver noise as a function of oscillator type.

  7. 75 FR 61478 - D'Lo Gas Storage, LLC; Notice of Petition

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... formation for natural gas storage, all as more fully set forth in the application, which is on file with the... Federal Energy Regulatory Commission D'Lo Gas Storage, LLC; Notice of Petition September 24, 2010. Take notice that on September 21, 2010, D'Lo Gas Storage, LLC (Petitioner), 1002 East St. Mary...

  8. THE NATURE OF LoBAL QSOs. I. SEDs AND MID-INFRARED SPECTRAL PROPERTIES

    SciTech Connect

    Lazarova, Mariana S.; Canalizo, Gabriela; Lacy, Mark; Sajina, Anna E-mail: gabriela.canalizo@ucr.edu E-mail: Anna.Sajina@tufts.edu

    2012-08-10

    We have obtained Spitzer Infrared Spectrograph spectra and MIPS 24, 70, and 160 {mu}m photometry for a volume-limited sample of 22 Sloan Digital Sky Survey selected low-ionization broad absorption line (LoBALs) QSOs at 0.5 < z < 0.6. By comparing their mid-IR spectral properties and far-IR spectral energy distributions (SEDs) with those of a control sample of 35 non-LoBALs matched in M{sub i} , we investigate the differences between the two populations in terms of their infrared emission and star formation (SF) activity. Twenty-five percent of the LoBALs show polycyclic aromatic hydrocarbon features and 45% have weak 9.7 {mu}m silicate dust emission. We model the SEDs and decouple the active galactic nucleus (AGN) and starburst contributions to the far-infrared luminosity in LoBALs and in non-LoBALs. Their median total, starburst, and AGN infrared luminosities are comparable. Twenty percent (but no more than 60%) of the LoBALs and 26% of the non-LoBALs are ultraluminous infrared galaxies (L{sub IR} > 10{sup 12} L{sub Sun }). We estimate star formation rates (SFRs) corrected for the AGN contribution to the FIR flux and find that LoBALs have comparable levels of SF activity to non-LoBALs when considering the entire samples. However, the SFRs of the IR-luminous LoBALs are 80% higher than those of their counterparts in the control sample. The median contribution of SF to the total far-infrared flux in LoBALs and in non-LoBALs is estimated to be 40%-50%, in agreement with previous results for Palomar-Green (PG) QSOs. Overall, our results show that there is no strong evidence from the mid- and far-IR properties that LoBALs are drawn from a different parent population than non-LoBALs.

  9. A ROACH Based Data Acquisition System for the Low Frequency All Sky Monitor (LoFASM)

    NASA Astrophysics Data System (ADS)

    Dartez, Louis P.; Jenet, F.; Cohen, S.; Creighton, T. D.; Ford, A.; Garcia, A.; Hicks, B.; Hinojosa, J.; Kassim, N. E.; Longoria, C.; Lunsford, G.; Mata, A.; Miller, R. B.; Price, R. H.; Quintero, L.; Ray, P. S.; Reser, J.; Rivera, J.; Stovall, K.; Taylor, G. B.

    2013-01-01

    The Low Frequency All Sky Monitor (LoFASM) is a distributed array of dipole antennas that are sensitive to radio frequencies from 5 to 88 MHz. The primary science goals will be the detection and study of low-frequency radio transients. LoFASM consists of antennas and front end electronics that were originally developed for the Long Wavelength Array (LWA) by the U.S. Naval Research Lab, the University of New Mexico, Virginia Tech, and the Jet Propulsion Laboratory. LoFASM, funded by the U.S. Department of Defense, will initially consist of 4 stations, each consisting of 12 dual-polarization dipole antenna stands. The signals received by LoFASM are digitized and processed using Reconfigurable Open Architecture Computing Hardware (ROACH) boards. This poster will describe the LoFASM project with an emphasis on the ROACH data processing pipe-line.

  10. From Leo Strauss to Collapse Theory: Considering the Neoconservative Attack on Modernity and the Work of Education

    ERIC Educational Resources Information Center

    Smith, David Geoffrey

    2008-01-01

    This paper locates the work of Leo Strauss within the broader conservative assault on modernity and especially its roots in liberalism. Four themes from Strauss's work are identified, then hermeneutically engaged for their relevance to educational practice in global times. The four themes are: (1) the liberal/modern concept of an open society is…

  11. LCT for EDRS: LEO to GEO optical communications at 1,8 Gbps between Alphasat and Sentinel 1a

    NASA Astrophysics Data System (ADS)

    Zech, H.; Heine, F.; Tröndle, D.; Seel, S.; Motzigemba, M.; Meyer, R.; Philipp-May, S.

    2015-10-01

    The European Data Relay System (EDRS) relies on optical communication links between Low Earth Orbit (LEO) and geostationary (GEO) spacecrafts. Data transmission at 1,8 Gbps between the S/Cs will be applied for link distances up to 45000 km. EDRS is foreseen to go into operation in 2015. As a precursor to the EDRS GEO Laser Communication Terminals (LCT), a LCT is embarked on the Alphasat GEO S/C, which was launched in July 2013. Sentinel 1A is a LEO earth observation satellite as part of ESAs Copernicus program. Sentinel 1A also has a LCT on board. In November 2014, the first optical communication link between a LEO and a GEO Laser Communication Terminal at gigabit data rates has been performed successfully [1]. Data generated by the Sentinel 1A instrument were optically transferred to Alphasat. From Alphasat, the data were transmitted via Kaband to a ground station. In the ground station, the original data were recovered successfully. So the whole chain from LEO to ground was verified. Since then, many optical communication links between the Alphasat LCT and the Sentinel 1A LCT were performed. During these tests, the acquisition and tracking performance was investigated. The first communication links showed a very robust link acquisition capability and tracking errors in the sub-μrad range. The communication link budget was verified and compared to the predictions, showing excellent overall system behavior with sufficient margin to support future GEO GEO link applications.

  12. Frontiers in Laser Cooling, Single-Molecule Biophysics, and Enrgy Science: A Talk from Leo Holberg and Allen Mills

    ScienceCinema

    Holberg, Leo; Mills, Allen [NIST

    2016-07-12

    Leo Holberg and Allen Mills present a talk at Frontiers in Laser Cooling, Single-Molecule Biophysics and Energy Science, a scientific symposium honoring Steve Chu, director of Lawrence Berkeley National Laboratory and recipient of the 1997 Nobel Prize in Physics. The symposium was held August 30, 2008 in Berkeley.

  13. Modeling of LEO Orbital Debris Populations in Centimeter and Millimeter Size Regimes

    NASA Technical Reports Server (NTRS)

    Xu, Y.-L.; Hill, . M.; Horstman, M.; Krisko, P. H.; Liou, J.-C.; Matney, M.; Stansbery, E. G.

    2010-01-01

    The building of the NASA Orbital Debris Engineering Model, whether ORDEM2000 or its recently updated version ORDEM2010, uses as its foundation a number of model debris populations, each truncated at a minimum object-size ranging from 10 micron to 1 m. This paper discusses the development of the ORDEM2010 model debris populations in LEO (low Earth orbit), focusing on centimeter (smaller than 10 cm) and millimeter size regimes. Primary data sets used in the statistical derivation of the cm- and mm-size model populations are from the Haystack radar operated in a staring mode. Unlike cataloged objects of sizes greater than approximately 10 cm, ground-based radars monitor smaller-size debris only in a statistical manner instead of tracking every piece. The mono-static Haystack radar can detect debris as small as approximately 5 mm at moderate LEO altitudes. Estimation of millimeter debris populations (for objects smaller than approximately 6 mm) rests largely on Goldstone radar measurements. The bi-static Goldstone radar can detect 2- to 3-mm objects. The modeling of the cm- and mm-debris populations follows the general approach to developing other ORDEM2010-required model populations for various components and types of debris. It relies on appropriate reference populations to provide necessary prior information on the orbital structures and other important characteristics of the debris objects. NASA's LEO-to-GEO Environment Debris (LEGEND) model is capable of furnishing such reference populations in the desired size range. A Bayesian statistical inference process, commonly adopted in ORDEM2010 model-population derivations, changes a priori distribution into a posteriori distribution and thus refines the reference populations in terms of data. This paper describes key elements and major steps in the statistical derivations of the cm- and mm-size debris populations and presents results. Due to lack of data for near 1-mm sizes, the model populations of 1- to 3.16-mm

  14. Simulation of the space debris environment in LEO using a simplified approach

    NASA Astrophysics Data System (ADS)

    Kebschull, Christopher; Scheidemann, Philipp; Hesselbach, Sebastian; Radtke, Jonas; Braun, Vitali; Krag, H.; Stoll, Enrico

    2017-01-01

    Several numerical approaches exist to simulate the evolution of the space debris environment. These simulations usually rely on the propagation of a large population of objects in order to determine the collision probability for each object. Explosion and collision events are triggered randomly using a Monte-Carlo (MC) approach. So in many different scenarios different objects are fragmented and contribute to a different version of the space debris environment. The results of the single Monte-Carlo runs therefore represent the whole spectrum of possible evolutions of the space debris environment. For the comparison of different scenarios, in general the average of all MC runs together with its standard deviation is used. This method is computationally very expensive due to the propagation of thousands of objects over long timeframes and the application of the MC method. At the Institute of Space Systems (IRAS) a model capable of describing the evolution of the space debris environment has been developed and implemented. The model is based on source and sink mechanisms, where yearly launches as well as collisions and explosions are considered as sources. The natural decay and post mission disposal measures are the only sink mechanisms. This method reduces the computational costs tremendously. In order to achieve this benefit a few simplifications have been applied. The approach of the model partitions the Low Earth Orbit (LEO) region into altitude shells. Only two kinds of objects are considered, intact bodies and fragments, which are also divided into diameter bins. As an extension to a previously presented model the eccentricity has additionally been taken into account with 67 eccentricity bins. While a set of differential equations has been implemented in a generic manner, the Euler method was chosen to integrate the equations for a given time span. For this paper parameters have been derived so that the model is able to reflect the results of the numerical MC

  15. A LEO Satellite Navigation Algorithm Based on GPS and Magnetometer Data

    NASA Technical Reports Server (NTRS)

    Deutschmann, Julie; Bar-Itzhack, Itzhack Y.; Harman, Rick

    2000-01-01

    The Global Position System (GPS) has become a standard method for low cost onboard satellite orbit determination. The use of GPS as an attitude and rate sensor has also been developed in the recent past. Additionally, focus has been given to attitude and orbit estimation using the magnetometer, a low cost, reliable sensor. Combining measurements from both GPS and a magnetometer can provide a robust navigation system which takes advantage of the estimation qualities of both measurements. Ultimately a low cost, accurate navigation system can result, potentially eliminating the need for more costly sensors, including gyroscopes. This work presents the development and preliminary testing of a unified navigation algorithm which produces estimates of attitude, angular rate, position, and velocity for a low earth orbit (LEO) spacecraft. The system relies on GPS phase, range, and range rate data as well as magnetometer data. The algorithm used is an extended Kalman filter (EKF) developed to provide LEO attitude, orbit, and rate estimates using magnetometer and sun sensor data. Incorporating sun sensor data into the EKF improved the attitude and rate estimates. For many LEO spacecraft the sun data is available during only a portion of the orbit. However, GPS data is available continuously throughout the orbit. GPS can produce accurate orbit estimates and combining GPS and magnetometer data improves the attitude and rate estimates. The magnetometer based EKF can converge from large initial errors in position, velocity, and 3 attitude . Combining the magnetometer and GPS data into a single EKF will provide a more robust and accurate system. The EKF is based on an existing EKF. The GPS measurement models for phase, range, and range rate are incorporated into the existing structure of the filter. The original EKF produced the orbit estimates in terms of Keplerian elements. Due to the nature of the GPS measurements and ease of computation, the orbit estimates are converted to

  16. GPU-accelerated Faint Streak Detection for Uncued Surveillance of LEO

    NASA Astrophysics Data System (ADS)

    Zimmer, P.; Ackermann, M.; McGraw, J. T.

    2013-09-01

    By astronomical standards, small objects (<10cm) in LEO illuminated by the Sun under terminator conditions are quite bright, depositing 100's to 1000's of photons per second into small telescope apertures (< 1m diameter). The challenge in discovering these objects with no a priori knowledge of their orbit (i.e. uncued surveillance) is that their relative motion with respect to a ground-based telescope makes them appear to have large angular rates of motion, up to and exceeding 1 degree per second. Thus in even a short exposure, the signal from the object is smeared out in a streak with low signal-to-noise per pixel. Go Green Termite (GGT), Inc. of Gilroy, CA, in collaboration with the University of New Mexico (UNM), is building two proof-of-concept wide-field imaging systems to test, develop and prove a novel streak detection technique. The imaging systems are built from off-the-shelf optics and detectors resulting in a 350mm aperture and a 6 square degree field of view. For streak detection, field of view is of critical importance because the maximum exposure time on the object is limited by its crossing time. In this way, wider fields of view impact surveys for LEO objects both by increasing the survey volume and increasing sensitivity. Using our newly GPU-accelerated detection scheme, the proof-of-concept systems are expected to be able to detect objects fainter than 12th magnitude moving at 1 degree per second and possibly as faint as 13th magnitude for slower moving objects. Meter-class optical systems using these techniques should be able to detect objects fainter than 14th magnitude, which is roughly equivalent to a golf ball at 1000km altitude. The goal of this work is to demonstrate a scalable system for near real time detection of fast moving objects that can be then handed off to other instruments capable of tracking and characterizing them. The two proof-of-concept systems, separated by ~30km, work together by taking simultaneous images of the same

  17. Time variable gravity retrieval and treatment of temporal aliasing using optical two-way links between GALILEO and LEO satellites

    NASA Astrophysics Data System (ADS)

    Hauk, Markus; Pail, Roland; Murböck, Michael; Schlicht, Anja

    2016-04-01

    For the determination of temporal gravity fields satellite missions such as GRACE (Gravity Recovery and Climate Experiment) or CHAMP (Challenging Minisatellite Payload) were used in the last decade. These missions improved the knowledge of atmospheric, oceanic and tidal mass variations. The most limiting factor of temporal gravity retrieval quality is temporal aliasing due to the undersampling of high frequency signals, especially in the atmosphere and oceans. This kind of error causes the typical stripes in spatial representations of global gravity fields such as from GRACE. As part of the GETRIS (Geodesy and Time Reference in Space) mission, that aims to establish a geodetic reference station and precise time- and frequency reference in space by using optical two-way communication links between geostationary (GEO) and low Earth orbiting (LEO) satellites, a possible future gravity field mission can be set up. By expanding the GETRIS space segment to the global satellite navigation systems (GNSS) the optical two-way links also connect the GALILEO satellites among themselves and to LEO satellites. From these links between GALILEO and LEO satellites gravitational information can be extracted. In our simulations inter-satellite links between GALILEO and LEO satellites are used to determine temporal changes in the Earth's gravitational field. One of the main goals of this work is to find a suitable constellation together with the best analysis method to reduce temporal aliasing errors. Concerning non-tidal aliasing, it could be shown that the co-estimation of short-period long-wavelength gravity field signals, the so-called Wiese approach, is a powerful method for aliasing reduction (Wiese et al. 2013). By means of a closed loop mission simulator using inter-satellite observations as acceleration differences along the line-of-sight, different mission scenarios for GALILEO-LEO inter-satellite links and different functional models like the Wiese approach are analysed.

  18. ALFALFA DISCOVERY OF THE NEARBY GAS-RICH DWARF GALAXY LEO P. III. AN EXTREMELY METAL DEFICIENT GALAXY

    SciTech Connect

    Skillman, Evan D.; Berg, Danielle A.; Olive, Keith A.; McQuinn, Kristen B. W. E-mail: berg@astro.umn.edu E-mail: kmcquinn@astro.umn.edu; and others

    2013-07-01

    We present KPNO 4 m and LBT/MODS spectroscopic observations of an H II region in the nearby dwarf irregular galaxy Leo P discovered recently in the Arecibo ALFALFA survey. In both observations, we are able to accurately measure the temperature sensitive [O III] {lambda}4363 line and determine a ''direct'' oxygen abundance of 12 + log(O/H) = 7.17 {+-} 0.04. Thus, Leo P is an extremely metal deficient (XMD) galaxy, and, indeed, one of the most metal deficient star-forming galaxies ever observed. For its estimated luminosity, Leo P is consistent with the relationship between luminosity and oxygen abundance seen in nearby dwarf galaxies. Leo P shows normal {alpha} element abundance ratios (Ne/O, S/O, and Ar/O) when compared to other XMD galaxies, but elevated N/O, consistent with the ''delayed release'' hypothesis for N/O abundances. We derive a helium mass fraction of 0.2509{sup +0.0184}{sub -0.0123}, which compares well with the WMAP + BBN prediction of 0.2483 {+-} 0.0002 for the primordial helium abundance. We suggest that surveys of very low mass galaxies compete well with emission line galaxy surveys for finding XMD galaxies. It is possible that XMD galaxies may be divided into two classes: the relatively rare XMD emission line galaxies which are associated with starbursts triggered by infall of low-metallicity gas and the more common, relatively quiescent XMD galaxies like Leo P, with very low chemical abundances due to their intrinsically small masses.

  19. Contrast Invariant Interest Point Detection by Zero-Norm LoG Filter.

    PubMed

    Zhenwei Miao; Xudong Jiang; Kim-Hui Yap

    2016-01-01

    The Laplacian of Gaussian (LoG) filter is widely used in interest point detection. However, low-contrast image structures, though stable and significant, are often submerged by the high-contrast ones in the response image of the LoG filter, and hence are difficult to be detected. To solve this problem, we derive a generalized LoG filter, and propose a zero-norm LoG filter. The response of the zero-norm LoG filter is proportional to the weighted number of bright/dark pixels in a local region, which makes this filter be invariant to the image contrast. Based on the zero-norm LoG filter, we develop an interest point detector to extract local structures from images. Compared with the contrast dependent detectors, such as the popular scale invariant feature transform detector, the proposed detector is robust to illumination changes and abrupt variations of images. Experiments on benchmark databases demonstrate the superior performance of the proposed zero-norm LoG detector in terms of the repeatability and matching score of the detected points as well as the image recognition rate under different conditions.

  20. LoCoH: nonparameteric kernel methods for constructing home ranges and utilization distributions.

    PubMed

    Getz, Wayne M; Fortmann-Roe, Scott; Cross, Paul C; Lyons, Andrew J; Ryan, Sadie J; Wilmers, Christopher C

    2007-02-14

    Parametric kernel methods currently dominate the literature regarding the construction of animal home ranges (HRs) and utilization distributions (UDs). These methods frequently fail to capture the kinds of hard boundaries common to many natural systems. Recently a local convex hull (LoCoH) nonparametric kernel method, which generalizes the minimum convex polygon (MCP) method, was shown to be more appropriate than parametric kernel methods for constructing HRs and UDs, because of its ability to identify hard boundaries (e.g., rivers, cliff edges) and convergence to the true distribution as sample size increases. Here we extend the LoCoH in two ways: "fixed sphere-of-influence," or r-LoCoH (kernels constructed from all points within a fixed radius r of each reference point), and an "adaptive sphere-of-influence," or a-LoCoH (kernels constructed from all points within a radius a such that the distances of all points within the radius to the reference point sum to a value less than or equal to a), and compare them to the original "fixed-number-of-points," or k-LoCoH (all kernels constructed from k-1 nearest neighbors of root points). We also compare these nonparametric LoCoH to parametric kernel methods using manufactured data and data collected from GPS collars on African buffalo in the Kruger National Park, South Africa. Our results demonstrate that LoCoH methods are superior to parametric kernel methods in estimating areas used by animals, excluding unused areas (holes) and, generally, in constructing UDs and HRs arising from the movement of animals influenced by hard boundaries and irregular structures (e.g., rocky outcrops). We also demonstrate that a-LoCoH is generally superior to k- and r-LoCoH (with software for all three methods available at http://locoh.cnr.berkeley.edu).

  1. LoCoH: Nonparameteric Kernel Methods for Constructing Home Ranges and Utilization Distributions

    PubMed Central

    Getz, Wayne M.; Fortmann-Roe, Scott; Wilmers, Christopher C.

    2007-01-01

    Parametric kernel methods currently dominate the literature regarding the construction of animal home ranges (HRs) and utilization distributions (UDs). These methods frequently fail to capture the kinds of hard boundaries common to many natural systems. Recently a local convex hull (LoCoH) nonparametric kernel method, which generalizes the minimum convex polygon (MCP) method, was shown to be more appropriate than parametric kernel methods for constructing HRs and UDs, because of its ability to identify hard boundaries (e.g., rivers, cliff edges) and convergence to the true distribution as sample size increases. Here we extend the LoCoH in two ways: “fixed sphere-of-influence,” or r-LoCoH (kernels constructed from all points within a fixed radius r of each reference point), and an “adaptive sphere-of-influence,” or a-LoCoH (kernels constructed from all points within a radius a such that the distances of all points within the radius to the reference point sum to a value less than or equal to a), and compare them to the original “fixed-number-of-points,” or k-LoCoH (all kernels constructed from k-1 nearest neighbors of root points). We also compare these nonparametric LoCoH to parametric kernel methods using manufactured data and data collected from GPS collars on African buffalo in the Kruger National Park, South Africa. Our results demonstrate that LoCoH methods are superior to parametric kernel methods in estimating areas used by animals, excluding unused areas (holes) and, generally, in constructing UDs and HRs arising from the movement of animals influenced by hard boundaries and irregular structures (e.g., rocky outcrops). We also demonstrate that a-LoCoH is generally superior to k- and r-LoCoH (with software for all three methods available at http://locoh.cnr.berkeley.edu). PMID:17299587

  2. LoCoH: Non-parameteric kernel methods for constructing home ranges and utilization distributions

    USGS Publications Warehouse

    Getz, Wayne M.; Fortmann-Roe, Scott; Cross, Paul C.; Lyons, Andrew J.; Ryan, Sadie J.; Wilmers, Christopher C.

    2007-01-01

    Parametric kernel methods currently dominate the literature regarding the construction of animal home ranges (HRs) and utilization distributions (UDs). These methods frequently fail to capture the kinds of hard boundaries common to many natural systems. Recently a local convex hull (LoCoH) nonparametric kernel method, which generalizes the minimum convex polygon (MCP) method, was shown to be more appropriate than parametric kernel methods for constructing HRs and UDs, because of its ability to identify hard boundaries (e.g., rivers, cliff edges) and convergence to the true distribution as sample size increases. Here we extend the LoCoH in two ways: ‘‘fixed sphere-of-influence,’’ or r -LoCoH (kernels constructed from all points within a fixed radius r of each reference point), and an ‘‘adaptive sphere-of-influence,’’ or a -LoCoH (kernels constructed from all points within a radius a such that the distances of all points within the radius to the reference point sum to a value less than or equal to a ), and compare them to the original ‘‘fixed-number-of-points,’’ or k -LoCoH (all kernels constructed from k -1 nearest neighbors of root points). We also compare these nonparametric LoCoH to parametric kernel methods using manufactured data and data collected from GPS collars on African buffalo in the Kruger National Park, South Africa. Our results demonstrate that LoCoH methods are superior to parametric kernel methods in estimating areas used by animals, excluding unused areas (holes) and, generally, in constructing UDs and HRs arising from the movement of animals influenced by hard boundaries and irregular structures (e.g., rocky outcrops). We also demonstrate that a -LoCoH is generally superior to k - and r -LoCoH (with software for all three methods available at http://locoh.cnr.berkeley.edu).

  3. Holographic wavefront sensor based on Karhunen-Loève decomposition

    NASA Astrophysics Data System (ADS)

    Anzuola, Esdras; Zepp, Andreas; Gladysz, Szymon; Stein, Karin

    2016-09-01

    In this paper we introduce the use of Karhunen-Loève functions as a basis set to decompose atmospheric phase aberrations in a digital holographic wavefront sensor (HWS). We show that the intermodal crosstalk when using Karhunen-Loève functions is reduced in comparison to the Zernike decomposition. Additionally, the sensor's response showed an improved linearity and better robustness to scintillation. Intermodal crosstalk remains a significant problem for this sensor but operation of an adaptive optics system based on HWS is less challenging when using Karhunen-Loève functions instead of Zernike polynomials.

  4. Higgs boson gluon-fusion production beyond threshold in N3LO QCD

    DOE PAGES

    Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; ...

    2015-03-18

    In this study, we compute the gluon fusion Higgs boson cross-section at N3LO through the second term in the threshold expansion. This calculation constitutes a major milestone towards the full N3LO cross section. Our result has the best formal accuracy in the threshold expansion currently available, and includes contributions from collinear regions besides subleading corrections from soft and hard regions, as well as certain logarithmically enhanced contributions for general kinematics. We use our results to perform a critical appraisal of the validity of the threshold approximation at N3LO in perturbative QCD.

  5. NGSLR's Measurement of the Retro-Reflector Array Response of Various LEO to GNSS Satellites

    NASA Technical Reports Server (NTRS)

    McGarry, Jan; Clarke, Christopher; Degnan, John; Donovan, Howard; Hall, Benjamin; Hovarth, Julie; Zagwodzki, Thomas

    2012-01-01

    "NASA's Next Generation Satellite Laser Ranging System (NGSLR) has successfully demonstrated daylight and nighttime tracking this year to s atellites from LEO to GNSS orbits, using a 7-8 arcsecond beam divergence, a 43% QE Hamamatsu MCP-PMT with single photon detection, a narrow field of view (11 arcseconds), and a 1 mJ per pulse 2kHz repetition rate laser. We have compared the actual return rates we are getting against the theoretical link calculations, using the known system confi guration parameters, an estimate of the sky transmission using locall y measured visibility, and signal processing to extract the signal from the background noise. We can achieve good agreement between theory and measurement in most passes by using an estimated pOinting error. We will s.()w the results of this comparison along with our conclusio ns."

  6. Attitude determination and control system design of the ITU-UUBF LEO1 satellite

    NASA Astrophysics Data System (ADS)

    Hajiyev, Ch.; Bahar, M.

    2003-01-01

    In this paper an attitude determination and control system for ITU-UUBF LEO1 satellite is proposed. To determine the attitude of the satellite this system uses algebraic method (2-vector algorithm). As a reference direction, the unit vectors toward the Sun and the Earth's center, and the Earth's magnetic field are used. Thus, it includes three different 2-vector algorithms based on using Earth's magnetic field-Sun vector, Earth's magnetic field-nadir vector, and nadir vector-Sun vector couples. A redundant data processing algorithm based on maximum likelihood was designed. The parameters of satellite's rotational motion are estimated using extended Kalman filter (EKF). For control purposes an EKF-based PD controller is designed. To reveal the performance of the designed system a simulation is made.

  7. Fatal infection with feline panleukopenia virus in two captive wild carnivores (Panthera tigris and Panthera leo).

    PubMed

    Duarte, Margarida D; Barros, Sílvia C; Henriques, Margarida; Fernandes, Teresa Lobo; Bernardino, Rui; Monteiro, Madalena; Fevereiro, Miguel

    2009-06-01

    Two cases of fatal infection caused by parvovirus in a white tiger (Panthera tigris) and an African lion (Panthera leo) at the Lisbon Zoo (Portugal) are described. Gross findings at necropsy were catharral enteritis in the tiger and severe hemorrhagic enteritis in the lion. Histopathologic examination revealed, in both animals, intestinal crypt necrosis and lymphocyte depletion in the germinal centers of the mesenteric lymph nodes. Bacteriologic examination was negative for common bacterial pathogens, including Salmonella. Amplification of the parvovirus VP2 complete gene was achieved in both cases and sequencing analysis identified these isolates as feline panleukopenia virus (FPLV). The nucleotide sequences obtained from these two viruses were genetically indistinguishable. The phylogenetic analysis of FPLV strains from domestic cats obtained in the Lisbon area revealed the circulation of FPLV strains highly similar to those isolated from the tiger and lion, which strongly suggests that stray cats may have been the source of infection.

  8. Three Canted Radiator Panels to Provide Adequate Cooling for Instruments on Slewing Spacecraft in LEO

    NASA Technical Reports Server (NTRS)

    Choi, Michael K.

    2012-01-01

    Certain free-flying spacecraft in low Earth orbit (LEO) or payloads on the International Space Station (ISS) are required to slew to point the telescopes at targets. Instrument detectors and electronics require cooling. Traditionally a planar thermal radiator is used. The temperature of such a radiator varies significantly when the spacecraft slews because its view factors to space vary significantly. Also for payloads on the ISS, solar impingement on the radiator is possible. These thermal adversities could lead to inadequate cooling for the instrument. This paper presents a novel thermal design concept that utilizes three canted radiator panels to mitigate this problem. It increases the overall radiator view factor to cold space and reduces the overall solar or albedo flux absorbed per unit area of the radiator.

  9. Location and removal of deslorelin acetate implants in female African lions (Panthera leo).

    PubMed

    Moresco, Anneke; Dadone, Liza; Arble, Jason; Klaphake, Eric; Agnew, Dalen W

    2014-06-01

    Contraception is necessary to manage zoo animal populations and to be able to house animals in groups without producing additional unwanted offspring. In felids and canids, an association between exposure to progestins and the occurrence of endometrial and mammary gland pathology has been documented. Therefore, the Association of Zoos and Aquariums (AZA) Wildlife Contraceptive Center recommends the use of deslorelin acetate for long-term contraception in carnivores. Return to cyclicity after deslorelin treatment has been variable; some individuals show ovarian suppression for long periods after the expected end of the deslorelin efficacy. In an attempt to reduce the time to reversal, techniques to locate and remove previous implants are being developed. This report documents the successful implementation of high-frequency ultrasonography in lions (Panthera leo) to locate and direct surgical removal of multiple deslorelin implants placed at least 2 yr previously as well as the return of follicular activity in both females at 7 months post-removal of implants.

  10. Analysis Of AVIRIS Data From LEO-15 Using Tafkaa Atmospheric Correction

    NASA Technical Reports Server (NTRS)

    Montes, Marcos J.; Gao, Bo-Cai; Davis, Curtiss O.; Moline, Mark

    2004-01-01

    We previously developed an algorithm named Tafkaa for atmospheric correction of remote sensing ocean color data from aircraft and satellite platforms. The algorithm allows quick atmospheric correction of hyperspectral data using lookup tables generated with a modified version of Ahmad & Fraser s vector radiative transfer code. During the past few years we have extended the capabilities of the code. Current modifications include the ability to account for within scene variation in solar geometry (important for very long scenes) and view geometries (important for wide fields of view). Additionally, versions of Tafkaa have been made for a variety of multi-spectral sensors, including SeaWiFS and MODIS. In this proceeding we present some initial results of atmospheric correction of AVIRIS data from the 2001 July Hyperspectral Coastal Ocean Dynamics Experiment (HyCODE) at LEO-15.

  11. A Dynamic/Anisotropic Low Earth Orbit (LEO) Ionizing Radiation Model

    NASA Technical Reports Server (NTRS)

    Badavi, Francis F.; West, Katie J.; Nealy, John E.; Wilson, John W.; Abrahms, Briana L.; Luetke, Nathan J.

    2006-01-01

    The International Space Station (ISS) provides the proving ground for future long duration human activities in space. Ionizing radiation measurements in ISS form the ideal tool for the experimental validation of ionizing radiation environmental models, nuclear transport code algorithms, and nuclear reaction cross sections. Indeed, prior measurements on the Space Transportation System (STS; Shuttle) have provided vital information impacting both the environmental models and the nuclear transport code development by requiring dynamic models of the Low Earth Orbit (LEO) environment. Previous studies using Computer Aided Design (CAD) models of the evolving ISS configurations with Thermo Luminescent Detector (TLD) area monitors, demonstrated that computational dosimetry requires environmental models with accurate non-isotropic as well as dynamic behavior, detailed information on rack loading, and an accurate 6 degree of freedom (DOF) description of ISS trajectory and orientation.

  12. A CRIRES-POP Atlas of the K Giant 10 Leo

    NASA Astrophysics Data System (ADS)

    Nicholls, C. P.; Lebzelter, T.

    2015-12-01

    The CRIRES-POP project (Lebzelter et al. [2]) will provide a public database of high-res, high S:N, NIR spectra of stars spanning the HR diagram. A relevant part of this library for the evolved star community will be the high quality reference spectra of several cool evolved giants. These atlases will be valuable references for future research, and will include comprehensive line identifications, abundance measurements, and isotope ratios, alongside stellar parameters derived through the inclusion of other data sources. All CRIRES observations have been completed, and reduction and analysis of the spectra, including improved telluric subtraction and wavelength calibration, is ongoing. We present here preliminary results of the first atlas to be produced, that of K1 III giant 10 Leo.

  13. Esophageal hiatal hernia in three exotic felines--Lynx lynx, Puma concolore, Panthera leo.

    PubMed

    Hettlich, Bianca F; Hobson, H Phil; Ducoté, Julie; Fossum, Theresa W; Johnson, James H

    2010-03-01

    Hiatal hernia was diagnosed in three exotic felines-lynx (Lynx lynx), cougar (Puma concolore), and lion (Panthera leo). All cats had a history of anorexia. Thoracic and abdominal radiographs showed evidence of a soft tissue mass within the caudal mediastinum suggestive of a hiatal hernia in all animals. A barium esophagram was performed in one case. All animals underwent thoracic or abdominal surgery for hernia reduction. Surgical procedures included: intercostal thoracotomy with herniorrhaphy and esophagopexy (lynx and cougar), and incisional gastropexy (lion). Concurrent surgical procedures performed were gastrotomy for gastric foreign body removal and jejunostomy tube placement. Clinical signs related to the hiatal hernia disappeared after surgery and recurrence of signs was not reported for the time of follow-up.

  14. Planetary nebulae as standard candles. IV - A test in the Leo I group

    NASA Technical Reports Server (NTRS)

    Ciardullo, Robin; Jacoby, George H.; Ford, Holland C.

    1989-01-01

    In this paper, PN are used to determine accurate distances to three galaxies in the Leo I group - The E0 giant elliptical NGC 3379, its optical companion, the SB0 spiral NGC 3384, and the smaller E6 elliptical NGC 3377. In all three galaxies, the luminosity-specific PN number densities are roughly the same, and the derived stellar death rates are in remarkable agreement with the predictions of stellar evolution theory. It is shown that the shape of the forbidden O III 5007 A PN luminosity function is the same in each galaxy and indistinguishable from that observed in M31 and M81. It is concluded that the PN luminosity function is an excellent standard candle for early-type galaxies.

  15. Hematologic and serum chemistry reference intervals for free-ranging lions (Panthera leo).

    PubMed

    Maas, Miriam; Keet, Dewald F; Nielen, Mirjam

    2013-08-01

    Hematologic and serum chemistry values are used by veterinarians and wildlife researchers to assess health status and to identify abnormally high or low levels of a particular blood parameter in a target species. For free-ranging lions (Panthera leo) information about these values is scarce. In this study 7 hematologic and 11 serum biochemistry values were evaluated from 485 lions from the Kruger National Park, South Africa. Significant differences between sexes and sub-adult (≤ 36 months) and adult (>36 months) lions were found for most of the blood parameters and separate reference intervals were made for those values. The obtained reference intervals include the means of the various blood parameter values measured in captive lions, except for alkaline phosphatase in the subadult group. These reference intervals can be utilized for free-ranging lions, and may likely also be used as reference intervals for captive lions.

  16. Cefovecin (Convenia) for the treatment of septic peritonitis in a female lion (Panthera leo).

    PubMed

    Steeil, James; Schumacher, Juergen; Seibert, Rachel; Tobias, Karen

    2012-09-01

    An 8-yr-old intact female African lion (Panthera leo) presented with a 3-day history of lethargy, anorexia, and vomiting. Hematologic and biochemical abnormalities included a leukocytosis, 41,700/microl (4,700-15,300) with a neutrophilia (37,530/microl; 2,000-9,200) and a left shift (1,250/microl bands; 0-300), and mild hypokalemia of 2.1 mEq/L (2.8-4.8). Abdominal radiographs revealed evidence of intestinal ileus, peritonitis, and the presence of effusion. An exploratory laparotomy was performed, and septic peritonitis due to a pyometra was diagnosed. The lion was treated with an ovariohysterectomy, abdominal lavage, fluid therapy, and a subcutaneous injection of cefovecin. The lion recovered, and clinical signs associated with septic peritonitis resolved within 36 hr. It was returned to conspecifics 3 wk later. Three months postoperatively, the lion showed no residual signs of septic peritonitis.

  17. Cholangiocarcinoma of intrahepatic bile ducts with disseminated metastases in an African lion (Panthera leo).

    PubMed

    Lepri, Elvio; Sforna, Monica; Brachelente, Chiara; Chiara, Brachelente; Vitellozzi, Giovanni; Giovanni, Vitellozzi

    2013-06-01

    A cholangiocarcinoma is reported in an 18-yr-old, female African lion (Panthera leo). The primary tumor consisted of multifocal to coalescing, hepatic, white-yellow masses distributed throughout the liver lobes. Metastases were present in regional lymph nodes, peritoneal surface, and lungs. Histologically, the tumor was characterized by a tubular pattern with alcian- and periodic acid-Schiff-positive secretory material in cystic spaces. The neoplastic cells were positive to broad-spectrum cytokeratins. Histochemical and immunohistochemical stains were consistent with bile duct carcinoma. Biliary tumors arising from the gallbladder have been reported in lions. However, to the authors' knowledge, this is the first case of intrahepatic bile duct carcinoma reported in an African lion.

  18. Age Estimation of African Lions Panthera leo by Ratio of Tooth Areas.

    PubMed

    White, Paula A; Ikanda, Dennis; Ferrante, Luigi; Chardonnet, Philippe; Mesochina, Pascal; Cameriere, Roberto

    2016-01-01

    Improved age estimation of African lions Panthera leo is needed to address a number of pressing conservation issues. Here we present a formula for estimating lion age to within six months of known age based on measuring the extent of pulp closure from X-rays, or Ratio Of tooth AReas (ROAR). Derived from measurements taken from lions aged 3-13 years for which exact ages were known, the formula explains 92% of the total variance. The method of calculating the pulp/tooth area ratio, which has been used extensively in forensic science, is novel in the study of lion aging. As a quantifiable measure, ROAR offers improved lion age estimates for population modeling and investigations of age-related mortality, and may assist national and international wildlife authorities in judging compliance with regulatory measures involving age.

  19. Congenital biliary tract malformation resembling biliary cystadenoma in a captive juvenile African lion (Panthera leo).

    PubMed

    Caliendo, Valentina; Bull, Andrew C J; Stidworthy, Mark F

    2012-12-01

    A captive 3-mo-old white African lion (Panthera leo) presented with clinical signs of acute pain and a distended abdomen. Despite emergency treatment, the lion died a few hours after presentation. Postmortem examination revealed gross changes in the liver, spleen, and lungs and an anomalous cystic structure in the bile duct. Histologic examination identified severe generalized multifocal to coalescent necrotizing and neutrophilic hepatitis, neutrophilic splenitis, and mild interstitial pneumonia, consistent with bacterial septicemia. The abnormal biliary structures resembled biliary cystadenoma. However, due to the age of the animal, they were presumed to be congenital in origin. Biliary tract anomalies and cystadenomas have been reported previously in adult lions, and this case suggests that at least some of these examples may have a congenital basis. It is unclear whether the lesion was an underlying factor in the development of hepatitis.

  20. A new concept for high-cycle-life LEO: Rechargeable MnO2-hydrogen

    NASA Technical Reports Server (NTRS)

    Appleby, A. John; Dhar, Y. J.; Murphy, O. J.; Srinivasan, Supramaniam

    1989-01-01

    The nickel-hydrogen secondary battery system is now the one of choice for use in GEO satellites. It offers superior energy density to that of nickel-cadmium, with a lifetime that is at least comparable in terms of both cycle life and overall operating life. While the number of deep cycles required for GEO use is small, LEO satellites with long lifetimes (5 to 10 years) will require secondary battery systems allowing 30,000 to 60,000 useful cycles which are characterized by an approximately 2C charge rate and C average discharge rate. Recent work has shown that birnessite MnO2 doped with bismuth oxide can be cycled at very high rates (6C) over a very large number of cycles (thousands) at depths-of-discharge in the 85 to 90 percent range, based on two electrons, which discharge at the same potential in a flat plateau. The potential is about 0.7 V vs. hydrogen, with a cut-off at 0.6 V. At first sight, this low voltage would seem to be a disadvantage, since the theoretical energy density will be low. However, it permits the use of lightweight materials that are immune from corrosion at the positive. The high utilization and low equivalent weight of the active material, together with the use of teflon-bonded graphite for current collection, result in very light positives, especially when these are compared with those in a derated nickel-hydrogen system. In addition, the weight of the pressure vessel falls somewhat, since the dead volume is lower. Calculations show that a total system will have 2.5 times the Ah capacity of a derated nickel-hydrogen LEO battery, so that the energy density, based on 1.2 V for nickel-hydrogen and 0.7 V for MnO2-hydrogen, will be 45 percent higher for comparable cycling performance.

  1. Comparison of magnetic perturbation data from LEO satellite constellations: Statistics of DMSP and AMPERE

    NASA Astrophysics Data System (ADS)

    Knipp, D. J.; Matsuo, T.; Kilcommons, L.; Richmond, A.; Anderson, B.; Korth, H.; Redmon, R.; Mero, B.; Parrish, N.

    2014-01-01

    During the past decade engineering-grade magnetic field measurements from the low Earth orbiting (LEO) Iridium constellation of communication satellites have been available to the geospace science community as a tool to map field-aligned currents. The Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) applied to Iridium measurements markedly improved the temporal and spatial resolution of these data. We developed new methods to compare data from the latest improvement to AMPERE with those from a constellation of four LEO Defense Meteorological Satellite Program (DMSP) spacecraft that carry high-resolution magnetometers. To perform the comparisons, we transformed all data to a common coordinate frame and altitude (110 km) and developed a means of computing spacecraft magnetic conjunctions. These conjunctions yield discrepancies in the magnetic field perturbations measured at each proximate spacecraft. During the geomagnetic disturbance of 29-30 May 2010, the vector differences in the horizontal perturbations at closest approach (typically a few tens of kilometers) had mean, median, and standard deviation values of 132 nT, 112 nT, and 90 nT, respectively. The DMSP spacecraft tend to report larger perturbations in the northern polar cap and cusp regions, especially during active intervals. We attribute some of the differences to limitations of spacecraft-attitude knowledge that propagate into AMPERE data. Overall, for the magnetic storm, we provide clear evidence that AMPERE data can provide high-resolution auroral zone data in good agreement with DMSP data for use in data assimilation algorithms. Such dual-use commercial data can provide important global augmentation to the nation's space weather monitoring capabilities.

  2. Coronal Loops Heating in the Atmosphere of the Ad Leo Red Dwarf

    NASA Astrophysics Data System (ADS)

    Zaitsev, V. V.; Kronshtadtov, P. V.

    2016-08-01

    We study the possible origin of long-lasting soft X-ray flares on the AD Leo star, which were observed onboard the Extreme Ultraviolet Explorer (EUVE) spacecraft for the period of 1993-2000 [1]. These flares have relatively long rise and decay times of the radiation intensity ( τ R ≈ 104 s and τ d ≈ 5 · 103, respectively), as well as a relatively large emission measure EM ≈ 1051cm-3, which exceeds by 1-3 orders of magnitude the emission measure of soft X-ray flares on the Sun. Assuming that the radiation appears in magnetic loops and basing on the observed values of the emission measure and radiation decay time, the authors of [1] determined the typical length overline{l}≈ 1.5\\cdot {10}^{10} cm , electron number density overline{n}≈ 3\\cdot {10}^{11}c{m}^{-3} , and plasma temperature overline{T}≈ 2.5\\cdot 107 K of the loops. This paper considers plasma heating due to dissipation of the electric currents in the coronal magnetic loops of the star induced by the photospheric convection. The large inductance of the loop as an equivalent electric circuit determines the long time of the current rise in the source and explains the observed time of plasma heating and the rise time of the X-ray radiation intensity. It is shown that the parameters of the X-ray sources in the AD Leo atmosphere agree with the parameters calculated under the assumption of simultaneous emission of a great number of loops (about 50) with electric currents greater than 1013 A, which exceeds the electric currents in the solar coronal magnetic loops by 1-3 orders of magnitude. Such an exceeding can be related to the higher photospheric convection velocities on the late-type stars compared with the Sun.

  3. Cycle life testing of lithium-ion batteries for small satellite LEO space missions

    SciTech Connect

    Mayer, S.T.; Feikert, J.H.; Kaschmitter, J.L.

    1993-08-16

    In 1990, Sony corporation announced their intention to manufacture a rechargeable lithium ion battery, based on the intercalation of lithium ions into a carbonaceous anode. The cells were first introduced for portable telephone use in June, 1991. (1) A 3.6V average cell voltage (4.1-2.75V range); (2) Excellent cycle life (1200 @ 100% DOD); (3) Good capacity retention (70% after 6 months); (4) Wide temperature range performance ({minus}20 to +60{degrees}C); (5) Excellent Discharge rate (82% capacity at 30 min. discharge rate); (6) Excellent Charge rate (100% Charge in <3 hrs); and (7) High energy density (264 W*hr/1 and 120 Whr/kg for ``D`` size cell. These specifications show significant promise for application of these batteries in low earth orbit (LEO) small satellites, particularly when compared to existing NiH{sub 2} and NiCd technology. The very high energy density and specific energy will reduce power system volume and weight. The wide temperature range enables simpler thermal design, particularly for new, small, high power satellites. The materials used in the lithium ion batteries are relatively inexpensive and benign, so that we expect costs to come down substantially in the future. The specified cycle life at 100% DOD is also 50% longer than most NiCds, so low DOD (depth of discharge) performance could be substantial. This study was undertaken to: (a) assess the feasibility for using lithium ion cells on small satellite LEO missions and (b) verify the claims of the manufacturer. This was accomplished by performing a detailed autopsy and various depth of discharge and rate tests on the cells. Of special interest was the cycle life performance of these cell at various depths of discharge DOD`s, to get an initial measure of the reduction in capacity fade with cycle conditions. Low DOD`s are used to extend the life of all batteries used in a space application.

  4. Proposal for a New LoD and Multi-Representation Concept for CityGML

    NASA Astrophysics Data System (ADS)

    Löwner, M.-O.; Gröger, G.; Benner, J.; Biljecki, F.; Nagel, C.

    2016-10-01

    The Open Geospatial Consortium (OGC) CityGML standard offers a Level of Detail (LoD) concept that enables the representation of CityGML features from a very detailed to a less detailed description. Due to a rising application variety, the current LoD concept seems to be too inflexible. Here, we present a multi representation concept (MRC) that enables a user-defined definition of LoDs. Because CityGML is an international standard, official profiles of the MRC are proposed. However, encoding of the defined profiles reveals many problems including mapping the conceptual model to the normative encoding, missing technologies and so on. Therefore, we propose to use the MRC as a meta model for the further definition of an LoD concept for CityGML 3.0.

  5. LINDLEY NURSERY COMPLEX NORTH loOKING SOUTHEAST ACROSS FORMER FIELDS THROUGH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    LINDLEY NURSERY COMPLEX NORTH loOKING SOUTHEAST ACROSS FORMER FIELDS THROUGH MORNING MIST - Overhills, Fort Bragg Military Reservation, Approximately 15 miles NW of Fayetteville, Overhills, Harnett County, NC

  6. LoPSiL: A Location-Based Policy-Specification Language

    NASA Astrophysics Data System (ADS)

    Ligatti, Jay; Rickey, Billy; Saigal, Nalin

    This paper describes the design of LoPSiL, a language for specifying location-dependent security and privacy policies. Policy- specification languages like LoPSiL are domain-specific programming languages intended to simplify the tasks of specifying and enforcing sound security policies on untrusted (i.e., potentially insecure) software. As far as we are aware, LoPSiL is the first imperative policy-specification language to provide abstractions specifically tailored to location-dependent policies for mobile-device applications. We have implemented a proof-of-concept compiler that inputs a LoPSiL policy P and a mobile-device application program A and outputs a new application program A' equivalent to A, except that A' contains inlined enforcement code that ensures that A' satisfies P at runtime. We report our experiences using this compiler to design and implement several policies for mobile-device applications.

  7. Development of HiLo Microscope and its use in In-Vivo Applications

    NASA Astrophysics Data System (ADS)

    Patel, Shreyas J.

    The functionality of achieving optical sectioning in biomedical research is invaluable as it allows for visualization of a biological sample at different depths while being free of background scattering. Most current microscopy techniques that offer optical sectioning, unfortunately, require complex instrumentation and thus are generally costly. HiLo microscopy, on the other hand, offers the same functionality and advantage at a relatively low cost. Hence, the work described in this thesis involves the design, build, and application of a HiLo microscope. More specifically, a standalone HiLo microscope was built in addition to implementing HiLo microscopy on a standard fluorescence microscope. In HiLo microscopy, optical sectioning is achieved by acquiring two different types of images per focal plane. One image is acquired under uniform illumination and the other is acquired under speckle illumination. These images are processed using an algorithm that extracts in-focus information and removes features and glare that occur as a result of background fluorescence. To show the benefits of the HiLo microscopy, several imaging experiments on various samples were performed under a HiLo microscope and compared against a traditional fluorescence microscope and a confocal microscope, which is considered the gold standard in optical imaging. In-vitro and ex-vivo imaging was performed on a set of pollen grains, and optically cleared mouse brain and heart slices. Each of these experiments showed great reduction in background scattering at different depths under HiLo microscopy. More importantly, HiLo imaging of optically cleared heart slice demonstrated emergence of different vasculature at different depths. Reduction of out-of-focus light increased the spatial resolution and allowed better visualization of capillary vessels. Furthermore, HiLo imaging was tested in an in-vivo model of a rodent dorsal window chamber model. When imaging the same sample under confocal microscope

  8. Effect of Propellant Flowrate and Purity on Carbon Deposition in LO2/Methane Gas Generators

    NASA Technical Reports Server (NTRS)

    Bossard, J. A.; Burkhardt, W. M.; Niiya, K. Y.; Braam, F.

    1989-01-01

    The generation and deposition of carbon was studied in the Carbon Deposition Program using subscale hardware with LO2/Liquid Natural Gas (LNG) and LO2/Methane propellants at low mixture ratios. The purpose of the testing was to evaluate the effect of methane purity and full scale injection density on carbon deposition. The LO2/LNG gas generator/preburner testing was performed at mixture ratios between 0.24 and 0.58 and chamber pressures from 5.8 to 9.4 MPa (840 to 1370 psia). A total of seven 200 second duration tests were performed. The LNG testing occurred at low injection densities, similar to the previous LO2/RP-1, LO2/propane, and LO2/methane testing performed on the carbon deposition program. The current LO2/methane test series occurred at an injection density factor of approximately 10 times higher than the previous testing. The high injection density LO2/methane testing was performed at mixture ratios between from 0.23 to 0.81 and chamber pressures from 6.4 to 15.2 MPa (925 to 2210 psia). A total of nine high injection density tests were performed. The testing performed demonstrated that low purity methane (LNG) did not produce any detectable change in carbon deposition when compared to pure methane. In addition, the C* performance and the combustion gas temperatures measured were similar to those obtained for pure methane. Similar results were obtained testing pure methane at higher propellant injection densities with coarse injector elements.

  9. Alfalfa discovery of the nearby gas-rich dwarf galaxy LEO P. V. Neutral gas dynamics and kinematics

    SciTech Connect

    Bernstein-Cooper, Elijah Z.; Pardy, Stephen A.; Cannon, John M. E-mail: spardy@astro.wisc.edu; and others

    2014-08-01

    We present new H I spectral line imaging of the extremely metal-poor, star-forming dwarf irregular galaxy Leo P. Our H I images probe the global neutral gas properties and the local conditions of the interstellar medium (ISM). The H I morphology is slightly elongated along the optical major axis. We do not find obvious signatures of interaction or infalling gas at large spatial scales. The neutral gas disk shows obvious rotation, although the velocity dispersion is comparable to the rotation velocity. The rotation amplitude is estimated to be V {sub c} =15 ± 5 km s{sup –1}. Within the H I radius probed by these observations, the mass ratio of gas to stars is roughly 2:1, while the ratio of the total mass to the baryonic mass is ≳15:1. We use this information to place Leo P on the baryonic Tully-Fisher relation, testing the baryonic content of cosmic structures in a sparsely populated portion of parameter space that has hitherto been occupied primarily by dwarf spheroidal galaxies. We detect the signature of two temperature components in the neutral ISM of Leo P; the cold and warm components have characteristic velocity widths of 4.2 ± 0.9 km s{sup –1} and 10.1 ± 1.2 km s{sup –1}, corresponding to kinetic temperature upper limits of ∼1100 K and ∼6200 K, respectively. The cold H I component is unresolved at a physical resolution of 200 pc. The highest H I surface densities are observed in close physical proximity to the single H II region. A comparison of the neutral gas properties of Leo P with other extremely metal-deficient (XMD) galaxies reveals that Leo P has the lowest neutral gas mass of any known XMD, and that the dynamical mass of Leo P is more than two orders of magnitude smaller than any known XMD with comparable metallicity.

  10. Estimating water vapour along the radio path between two LEO satellites through multifrequency differential power measurements

    NASA Astrophysics Data System (ADS)

    Facheris, Luca; Cuccoli, Fabrizio

    2013-04-01

    The Normalized Differential Spectral Attenuation (NDSA) concept was proposed in 2002 by the authors for tropospheric water vapour sounding by means of a couple of LEO (Low Earth Orbit) satellites (one carrying a transmitter, the other a receiver and operating in the Ku/K bands) in limb geometry. In those years, in the course of the ACE+ mission studies (second call for proposal of the ESA Earth Explorer Opportunity Mission), the problem arose of the severe impact of scintillation due to tropospheric turbulence on the water vapour estimates provided by radio occultation measurements made in limb mode between two LEO satellites. In following ESA studies (AlmetLeo - 2004, ACTLIMB -2009) it was demonstrated that NDSA, thanks to its normalised differential approach, is effective for limiting scintillation and for estimating the Integrated Water Vapor (IWV) along the propagation path between the two LEO satellites. NDSA relies on the conversion of a spectral parameter (the spectral sensitivity S), into the IWV through IWV-S relationships. S is a finite-difference approximation of the derivative of the spectral attenuation at a given frequency fo, normalized to the spectral attenuation itself. To measure Sat fo,it is required that two tone signals with equal power at relatively close frequencies f1 and f2 (f1 > f2) symmetrically placed around fo are simultaneously transmitted. The two pertinent received powers P1 and P2 are simultaneously measured and S is provided by: S = -P2--P1- (f1 - f2 )P2 From the very beginning of the NDSA studies, it was evident that in ideal measurement conditions (no disturbance at the receiver nor propagation impairments) S is tightly correlated to the IWV. To verify this, we accounted for natural variations of the atmospheric conditions by generating simulated spherically symmetric atmospheres using real radiosonde profiles. We computed IWV along the radio path and simulated S separately obtaining IWV-S relationships at various altitudes

  11. Comparison of currents predicted by NASCAP/LEO model simulations with elementary Langmuir-type bare probe models for an insulated cable containing a single pinhole

    NASA Technical Reports Server (NTRS)

    Galofaro, Joel T.

    1990-01-01

    The behavior of a defect in the insulation of a short biased section of cable in a Low Earth Orbit (LEO) space environment was examined. Such studies are of the utmost importance for large space power systems where great quantities of cabling will be deployed. An insulated probe containing a pinhole was placed into a hypothetical high speed LEO plasma. The NASA Charging Analyzer Program (NASCAP/LEO) was used to explore sheath growth about the probe as a function of applied voltage and to predict I-V behavior. A set of independent current calculations using Langmuir's formulations for concentric spheres and coaxial cylinders were also performed. The case of concentric spheres was here extended to include the case of concentric hemispheres. Several simple Langmuir-type models were then constructed to bracket the current collected by the cable. The space-charge sheath radius and impact parameters were used to determine the proper current regime. I-V curves were plotted for the models and comparisons were made with NASCAP/LEO results. Finally, NASCAP/LEO potential contours and surface cell potential plots were examined to explain interesting features in the NASCAP/LEO I-V curve.

  12. Deep analysis of Raman spectra of ZnO:Mo and ZnO:In sprayed thin films along with LO and TA+LO bands investigation

    NASA Astrophysics Data System (ADS)

    Souissi, A.; Amlouk, M.; Khemakhem, H.; Guermazi, S.

    2016-04-01

    ZnO and Mo, In doped ZnO thin films with the molar ratios (Mo/Zn) and (In/Zn) were dosed at 1%, 2% and 3%, respectively. These films were deposited on amorphous SiO2 substrate at 460 °C by the spray-pyrolysis process. A useful and concise reminder of the spatial resolutions of Raman spectroscopy was presented. The vibrational responses of these films at high doping exhibited strong fluctuations that were resolved by successive digital processing, choice of the optimal profile of the baseline, suppression of fluorescence and/or photoluminescence, and noise reduction. These treated spectra have allowed to identify possible multi-modes in highly doped studied samples and revealed the presence of LO and TA+LO broad bands, whose second was at cascade and could be explored in optoelectronic and sensitive systems.

  13. Impedance measurements on a spiral-wound nickel/metal hydride cell cycled in a simulated Leo orbit

    NASA Technical Reports Server (NTRS)

    Reid, Margaret A.

    1993-01-01

    A spiral-wound size C cell was cycled at 25 C in a low earth orbit (LEO) regime at 50 percent depth of discharge (DOD) with approximately five percent over-charge. The nominal capacity was 3.5 AH. The cell was cycled for 2000 cycles. Capacity checks and impedance measurements over the complete range of state of charge were made upon receipt and after 500, 1000, and 2000 cycles. The capacity of the cell was essentially unchanged until after the impedance measurements at 2000 cycles. Only small changes in the impedance parameters were observed, but there was somewhat more scatter in the data after 2000 cycles. When the cell was returned to LEO cycling after 2000 cycles, only 38 percent of the capacity could be obtained. It is believed that the cell failed because of an equipment failure at the end of the final impedance measurements which allowed an over-discharge.

  14. An Updated Zero Boil-Off Cryogenic Propellant Storage Analysis Applied to Upper Stages or Depots in a LEO Environment

    NASA Technical Reports Server (NTRS)

    Plachta, David; Kittel, Peter

    2003-01-01

    Previous efforts have shown the analytical benefits of zero boil-off (ZBO) cryogenic propellant storage in launch vehicle upper stages of Mars transfer vehicles for conceptual Mars Missions. However, recent NASA mission investigations have looked at a different and broad array of missions, including a variety of orbit transfer vehicle (OTV) propulsion concepts, some requiring cryogenic storage. For many of the missions, this vehicle will remain for long periods (greater than one week) in low earth orbit (LEO), a relatively warm thermal environment. Under this environment, and with an array of tank sizes and propellants, the performance of a ZBO cryogenic storage system is predicted and compared with a traditional, passive-only storage concept. The results show mass savings over traditional, passive-only cryogenic storage when mission durations are less than one week in LEO for oxygen, two weeks for methane, and roughly 2 months for LH2. Cryogenic xenon saves mass over passive storage almost immediately.

  15. Mission Analysis for LEO Microwave Power-Beaming Station in Orbital Launch of Microwave Lightcraft

    NASA Technical Reports Server (NTRS)

    Myrabo, L. N.; Dickenson, T.

    2005-01-01

    A detailed mission analysis study has been performed for a 1 km diameter, rechargeable satellite solar power station (SPS) designed to boost 20m diameter, 2400 kg Micr,oWave Lightcraft (MWLC) into low earth orbit (LEO) Positioned in a 476 km daily-repeating oi.bit, the 35 GHz microwave power station is configured like a spinning, thin-film bicycle wheel covered by 30% efficient sola cells on one side and billions of solid state microwave transmitter elements on the other, At the rim of this wheel are two superconducting magnets that can stor,e 2000 G.J of energy from the 320 MW, solar array over a period of several orbits. In preparation for launch, the entire station rotates to coarsely point at the Lightcraft, and then phases up using fine-pointing information sent from a beacon on-board the Lightcraft. Upon demand, the station transmits a 10 gigawatt microwave beam to lift the MWLC from the earth surface into LEO in a flight of several minutes duration. The mission analysis study was comprised of two parts: a) Power station assessment; and b) Analysis of MWLC dynamics during the ascent to orbit including the power-beaming relationships. The power station portion addressed eight critical issues: 1) Drag force vs. station orbital altitude; 2) Solar pressure force on the station; 3) Station orbital lifetime; 4) Feasibility of geo-magnetic re-boost; 5) Beta angle (i..e., sola1 alignment) and power station effective area relationship; 6) Power station percent time in sun vs, mission elapsed time; 7) Station beta angle vs.. charge time; 8) Stresses in station structures.. The launch dynamics portion examined four issues: 1) Ascent mission/trajecto1y profile; 2) MWLC/power-station mission geometry; 3) MWLC thrust angle vs. time; 4) Power station pitch rate during power beaming. Results indicate that approximately 0 58 N of drag force acts upon the station when rotated edge-on to project the minimum frontal area of 5000 sq m. An ion engine or perhaps an electrodynamic

  16. The Komplast Experiment: Space Environmental Effects after 12 Years in LEO (and Counting)

    NASA Technical Reports Server (NTRS)

    Shaevich, S. K.; Aleksandrov, N. G.; Shumov, A. E.; Novikov, L. S.; Alred, J. A.; Shindo, D. J.; Kravchenko, M.; Golden, J. L.

    2013-01-01

    The Komplast materials experiment was designed by the Khrunichev State Research and Production Space Center, together with other Russian scientific institutes, and has been carried out by Mission Control Moscow since 18. Komplast panels fitted with material samples and sensors were located on the International Space Station (ISS) Functional Cargo Block (FGB) module exterior surface. Within the framework of this experiment, the purpose was to study the effect of the low earth orbit (LEO) environment on exposed samples of various materials. The panels were sent into orbit with the FGB when it launched on November 20, 1998. Panels #2 and #10 were retrieved during Russian extravehicular activity in February 2011 and sealed within cases to temporarily protect the samples from exposure to air until they could be studied on the ground. Panel #2 contained an experiment to detect micrometeoroid and orbital debris (MMOD) impacts, radiation and UV sensors, several pieces of electrical cable, and samples made from elastomeric and fluoroplastic materials. Panel #10 contained a temperature sensor, and both carbon composite and adhesive-bonded samples. A figure shows the location of panels #2 and #10 on the FGB module aft endcone. The panels were subsequently returned to Earth by Space Shuttle Discovery on the STS-133/ULF-5 mission after 12 years of LEO exposure and opened in an argon chamber at the Institute of Nuclear Physics at Moscow State University in July 2011. Based on the results of analyzing the readings from sensors located on Komplast panels and in studying material samples from the panels, the comprehensive effect of spaceflight factors on the FGB (at the locations of Panels #2 and #10) was evaluated. Total solar exposure was determined to be 960 +/- 200 kJ/square cm or 21,000 equivalent solar hours. Because of location of these two panels and the ISS flight attitude, atomic oxygen (AO) fluence was relatively low for such a long duration exposure, approximately 1.5x

  17. Chemistry and Kinematics of the Late-forming Dwarf Irregular Galaxies Leo A, Aquarius, and Sagittarius DIG

    NASA Astrophysics Data System (ADS)

    Kirby, Evan N.; Rizzi, Luca; Held, Enrico V.; Cohen, Judith G.; Cole, Andrew A.; Manning, Ellen M.; Skillman, Evan D.; Weisz, Daniel R.

    2017-01-01

    We present Keck/DEIMOS spectroscopy of individual stars in the relatively isolated Local Group dwarf galaxies Leo A, Aquarius, and the Sagittarius dwarf irregular galaxy. The three galaxies—but especially Leo A and Aquarius—share in common delayed star formation histories (SFHs) relative to many other isolated dwarf galaxies. The stars in all three galaxies are supported by dispersion. We found no evidence of stellar velocity structure, even for Aquarius, which has rotating H i gas. The velocity dispersions indicate that all three galaxies are dark-matter-dominated, with dark-to-baryonic mass ratios ranging from {4.4}-0.8+1.0 (SagDIG) to {9.6}-1.8+2.5 (Aquarius). Leo A and SagDIG have lower stellar metallicities than Aquarius, and they also have higher gas fractions, both of which would be expected if Aquarius were further along in its chemical evolution. The metallicity distribution of Leo A is inconsistent with a closed or leaky box model of chemical evolution, suggesting that the galaxy was pre-enriched or acquired external gas during star formation. The metallicities of stars increased steadily for all three galaxies, but possibly at different rates. The [α/Fe] ratios at a given [Fe/H] are lower than that of the Sculptor dwarf spheroidal galaxy, which indicates more extended SFHs than Sculptor, consistent with photometrically derived SFHs. Overall, the bulk kinematic and chemical properties for the late-forming dwarf galaxies do not diverge significantly from those of less delayed dwarf galaxies, including dwarf spheroidal galaxies. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  18. Sizing of "Mother Ship and Catcher" Missions for LEO Small Debris and for GEO Large Object Capture

    NASA Technical Reports Server (NTRS)

    Bacon, John B.

    2009-01-01

    Most LEO debris lies in a limited number of inclination "bands" associated with specific useful orbits. Objects in such narrow inclination bands have all possible Right Ascensions of Ascending Node (RAANs), creating a different orbit plane for nearly every piece of debris. However, a low-orbiting satellite will always phase in RAAN faster than debris objects in higher orbits at the same inclination, potentially solving the problem. Such a low-orbiting base can serve as a "mother ship" that can tend and then send small, disposable common individual catcher/deboost devices--one for each debris object--as the facility drifts into the same RAAN as each higher object. The dV necessary to catch highly-eccentric orbit debris in the center of the band alternatively allows the capture of less-eccentric debris in a wider inclination range around the center. It is demonstrated that most LEO hazardous debris can be removed from orbit in three years, using a single LEO launch of one mother ship--with its onboard magazine of freeflying low-tech catchers--into each of ten identified bands, with second or potentially third launches into only the three highest-inclination bands. The nearly 1000 objects near the geostationary orbit present special challenges in mass, maneuverability, and ultimate disposal options, leading to a dramatically different architecture and technology suite than the LEO solution. It is shown that the entire population of near-GEO derelict objects can be gathered and tethered together within a 3 year period for future scrap-yard operations using achievable technologies and only two earth launches.

  19. Propagation of Forecast Errors from the Sun to LEO Trajectories: How Does Drag Uncertainty Affect Conjunction Frequency?

    DTIC Science & Technology

    2014-09-01

    density is in turn strongly controlled by incident ultraviolet radiation from the sun . Accordingly, modeling and forecasting upper atmospheric density...Propagation of Forecast Errors from the Sun to LEO Trajectories: How Does Drag Uncertainty Affect Conjunction Frequency? John Emmert, Jeff Byers...trajectories of most objects in low- Earth orbit, and solar variability is the largest source of error in upper atmospheric density forecasts. There is

  20. The Application of GIM in Precise Orbit Determination for LEO Satellites with Single-Frequency GPS Measurements

    NASA Astrophysics Data System (ADS)

    Peng, Dong-ju; Wu, Bin

    2012-10-01

    With the precise GPS ephemeris and clock error available, the iono- spheric delay is left as the dominant error source in the single-frequency GPS data. Thus, the removal of ionospheric effects is a ma jor prerequisite for an improved orbit reconstruction of LEO satellites based on the single-frequency GPS data. In this paper, the use of Global Ionospheric Maps (GIM) in kine- matic and dynamic orbit determinations for LEO satellites with single-frequency GPS pseudorange measurements is discussed first, and then, estimating the iono- spheric scale factor to remove the ionospheric effects from the C/A-code pseu- dorange measurements for both kinematic and dynamic orbit determinations is addressed. As it is known that the ionospheric delay of space-borne GPS sig- nals is strongly dependent on the orbit altitudes of LEO satellites, we select the real C/A-code pseudorange measurement data of the CHAMP, GRACE, TerraSAR-X and SAC-C satellites with altitudes between 300 km and 800 km as sample data in this paper. It is demonstrated that the approach to eliminating ionospheric effects in C/A-code pseudorange measurements by estimating the ionospheric scale factor is highly effective. Employing this approach, the accu- racy of both kinematic and dynamic orbits can be improved notably. Among those five LEO satellites, CHAMP with the lowest orbit altitude has the most remarkable improvements in orbit accuracy, which are 55.6% and 47.6% for kine- matic and dynamic orbits, respectively. SAC-C with the highest orbit altitude has the least improvements in orbit accuracy accordingly, which are 47.8% and 38.2%, respectively.

  1. Initial Verification of the GPS-LEO Occultation Technique of Mapping the Atmosphere with the GPS-MET Experiment

    NASA Technical Reports Server (NTRS)

    Hajj, G. A.; Kursinski, E. R.; Bertiger, W. I.; Leroy, S. S.; Romans, L. J.; Schofield, J. T.

    1995-01-01

    The radio occultation technique was first used to observe Earth's atmosphere in April 1995 when a high performance Global Positioning System (GPS) receiver was placed into a low-Earth orbit. When a signal from the GPS travels through the ionosphere and the neutral atmosphere, and is received by a low-Earth orbiter (LEO) satellite, occultation data is generated. How that data is analyzed is presented.

  2. Cutaneous squamous cell carcinoma presenting as a wound with discharging sinus tracts in a wild African lion (Panthera leo).

    PubMed

    Mwase, M; Mumba, C; Square, D; Kawarai, S; Madarame, H

    2013-11-01

    A female wild African lion (Panthera leo) was presented with an 8-month history of a wound with multiple discharging sinus tracts on the left paw. Microscopical examination revealed squamous cell carcinoma (SCC). To the best of our knowledge, this is the first report of cutaneous SCC in an African lion. Cutaneous SCC presenting as discharging sinus tracts lined by neoplastic squamous cells has not been reported previously in animals.

  3. Coronal Dynamics and Complete Flare Energy Budget for the M Dwarf AD Leo

    NASA Technical Reports Server (NTRS)

    Brown, Alexander; Sonneborn, Georgwe (Technical Monitor)

    2005-01-01

    This grant supported the observing and data analysis for FUSE Cycle 3 project C114 to observe the flare star AD Leo for 50 ksec coordinated with HST (Hubble Space Telescope) STIS ultraviolet spectroscopy and Chandra X-ray spectroscopy. Unfortunately, it was impossible to obtain the planned FUSE observations because AD Leo is a low declination target (delta approximately 20 degrees) and was rendered unobservable by restrictions in the sky coverage for FUSE observations. In April 2002 another M dwarf star, EV Lac, which is at significantly higher declination, was substituted for this project. EV Lac was observed by FUSE for a cumulative exposure of 35 ksec on 2002 July 1. The observation used the large LWRS aperture and collected data in time-tagged mode. The LWRS aperture is large enough that the target should remain within the aperture despite the normal level of pointing jitter and target drift experienced during FUSE observing. Our examination of the stellar signal showed that the target was well within the aperture throughout the observation. The data were split into night-time and day-time data so that the effects of airglow emission were recognizable. No obvious flaring, the primary science objective, was detected during the observation. The only stellar lines detected are 0 VI 1031.9, 1037.6 Angstrom, and the C III 1175 Angstrom, UV multiplet and the 977 Angstrom, resonance line. A comparison of the day-time and night-time spectra show that the 0 VI lines and the C III intersystem multiplet are unaffected by airglow features. The day-time data 977 Angstrom profile shows the presence of significant scattered solar C III photons, which should not be present in the night time spectrum. Emission fluxes for these lines were measured by direct summation of the emission lines. No continuum signal was detected in the region of these lines. The cleanest emission line profiles are for the O VI lines and we performed Gaussian fitting for these profiles. Both lines are

  4. Human Operations Beyond LEO by the End of the Decade: An Affordable Near-Term "Stepping Stone"

    NASA Technical Reports Server (NTRS)

    Thronson, Harley; Lester, Dan; Talay, Ted

    2010-01-01

    For more than a decade, several teams have assessed designs for a long-duration free-space human habitat beyond low-Earth orbit (LEO), building upon years of hard-won experience with the International Space Station (ISS). These systems would enable multiple achievements for science and human space flight. Most were intended to be deployed using available or near-future capabilities within about a decade after funding begins and serve as the first major human "stepping stone" beyond LEO. Last year, Thronson and Talay summarized work up to that time on expandable or inflatable concepts for deployment at an Earth-Moon (E-M) L1 or L2 location. Here we summarize our team's more recent work both on a long-duration human habitat that could be deployed beyond LEO within a decade and on the priority goals that such a habitat might accomplish. Particulars of this and other concepts for human operations in cis-lunar space are posted on the web and will be presented at professional conferences, and detailed in future publications by our group.

  5. First Asian record of Panthera (Leo) fossilis (Mammalia, Carnivora, Felidae) in the Early Pleistocene of Western Siberia, Russia.

    PubMed

    Sotnikova, Marina V; Foronova, Irina V

    2014-08-01

    A lion-like pantherine felid is described as Panthera (Leo) fossilis from the late Early Pleistocene sediments of the Kuznetsk Basin (Western Siberia, Russia). The find of P. fossilis first recorded in Asia considerably extends the current notion of the eastward expansion of the most ancient lions. The Siberian lion is geologically the oldest form and is dimensionally among the largest members of the group of fossil lions on the Eurasian continent. Although known by mandibular remains only, it is readily distinguished from Panthera (Leo) spelaea by a heavy built mandibular corpus with rectangular profile in the cheek teeth area, a deep, well-outlined and narrow anterior section of the masseteric fossa, and a large p4 supported by a big unreduced anterior root. The Siberian lion shares these features with the European Middle Pleistocene P. fossilis and the American Late Pleistocene P. (Leo) atrox, which suggests their close relationship. P. atrox originated from P. fossilis and was isolated in North America south of the Late Pleistocene ice sheets. This explains why the American lion has retained more primitive features than the coeval Eurasian cave lion P. (L.) spelaea.

  6. Human Exploration Beyond LEO by the End of the Decade: Designs for Long-Duration "Gateway" Habitats

    NASA Technical Reports Server (NTRS)

    Thronson, Harley; Barr, Jonathan; Budinoff, Jason; Dorsey, John; Gold, Michael; Kutter, Bernard; Lester, Daniel; Moe, Rud; Sauls, Bobby; Spampinato, Phillip; Spexarth, Gary; Sullivan, Gregory; Talay, Ted; Watson, Judith

    2010-01-01

    For the past few years, designs have been developed that are intended to demonstrate that a long-duration habitation system beyond LEO is plausible within several years. Here we summarize a pair of designs with the overriding goal of development and operation beyond LEO before the end of the decade that also build upon experiments and lessons learned from ISS. Both concepts here have the goal of an expandable long-duration habitat at Earth- Moon L1 and/or L2. Both options require subsequent launches for the astronauts. If a heavy-lift launch vehicle is available this decade, an expandable 30.5 mt habitat and departure-stage propulsion system may be launched to E-M L1,2 in a single launch and will offer 575 cubic meter (roughly half the habitable volume of ISS) If existing (or near-future) EELVs are the available launch vehicles this decade, a 16 mt, 170 cubic meter design that uses a pair of launches of Delta IV H and LEO rendezvous/fuel transfer to reach E-M L1,2.

  7. Structure-Function Elucidation of a New α-Conotoxin, Lo1a, from Conus longurionis

    PubMed Central

    Lebbe, Eline K. M.; Peigneur, Steve; Maiti, Mohitosh; Devi, Prabha; Ravichandran, Samuthirapandian; Lescrinier, Eveline; Ulens, Chris; Waelkens, Etienne; D'Souza, Lisette; Herdewijn, Piet; Tytgat, Jan

    2014-01-01

    α-Conotoxins are peptide toxins found in the venom of marine cone snails and potent antagonists of various subtypes of nicotinic acetylcholine receptors (nAChRs). nAChRs are cholinergic receptors forming ligand-gated ion channels in the plasma membranes of certain neurons and the neuromuscular junction. Because nAChRs have an important role in regulating transmitter release, cell excitability, and neuronal integration, nAChR dysfunctions have been implicated in a variety of severe pathologies such as epilepsy, myasthenic syndromes, schizophrenia, Parkinson disease, and Alzheimer disease. To expand the knowledge concerning cone snail toxins, we examined the venom of Conus longurionis. We isolated an 18-amino acid peptide named α-conotoxin Lo1a, which is active on nAChRs. To the best of our knowledge, this is the first characterization of a conotoxin from this species. The peptide was characterized by electrophysiological screening against several types of cloned nAChRs expressed in Xenopus laevis oocytes. The three-dimensional solution structure of the α-conotoxin Lo1a was determined by NMR spectroscopy. Lo1a, a member of the α4/7 family, blocks the response to acetylcholine in oocytes expressing α7 nAChRs with an IC50 of 3.24 ± 0.7 μm. Furthermore, Lo1a shows a high selectivity for neuronal versus muscle subtype nAChRs. Because Lo1a has an unusual C terminus, we designed two mutants, Lo1a-ΔD and Lo1a-RRR, to investigate the influence of the C-terminal residue. Lo1a-ΔD has a C-terminal Asp deletion, whereas in Lo1a-RRR, a triple-Arg tail replaces the Asp. They blocked the neuronal nAChR α7 with a lower IC50 value, but remarkably, both adopted affinity for the muscle subtype α1β1δϵ. PMID:24567324

  8. An Orientation Dependent Size Illusion Is Underpinned by Processing in the Extrastriate Visual Area, LO1

    PubMed Central

    Mikellidou, Kyriaki; Gouws, André D.; Clawson, Hannah; Thompson, Peter; Morland, Antony B.

    2016-01-01

    We use the simple, but prominent Helmholtz’s squares illusion in which a vertically striped square appears wider than a horizontally striped square of identical physical dimensions to determine whether functional magnetic resonance imaging (fMRI) BOLD responses in V1 underpin illusions of size. We report that these simple stimuli which differ in only one parameter, orientation, to which V1 neurons are highly selective elicited activity in V1 that followed their physical, not perceived size. To further probe the role of V1 in the illusion and investigate plausible extrastriate visual areas responsible for eliciting the Helmholtz squares illusion, we performed a follow-up transcranial magnetic stimulation (TMS) experiment in which we compared perceptual judgments about the aspect ratio of perceptually identical Helmholtz squares when no TMS was applied against selective stimulation of V1, LO1, or LO2. In agreement with fMRI results, we report that TMS of area V1 does not compromise the strength of the illusion. Only stimulation of area LO1, and not LO2, compromised significantly the strength of the illusion, consistent with previous research that LO1 plays a role in the processing of orientation information. These results demonstrate the involvement of a specific extrastriate area in an illusory percept of size. PMID:27733896

  9. Optically sectioned in vivo imaging with speckle illumination HiLo microscopy

    NASA Astrophysics Data System (ADS)

    Lim, Daryl; Ford, Tim N.; Chu, Kengyeh K.; Mertz, Jerome

    2011-01-01

    We present a simple wide-field imaging technique, called HiLo microscopy, that is capable of producing optically sectioned images in real time, comparable in quality to confocal laser scanning microscopy. The technique is based on the fusion of two raw images, one acquired with speckle illumination and another with standard uniform illumination. The fusion can be numerically adjusted, using a single parameter, to produce optically sectioned images of varying thicknesses with the same raw data. Direct comparison between our HiLo microscope and a commercial confocal laser scanning microscope is made on the basis of sectioning strength and imaging performance. Specifically, we show that HiLo and confocal 3-D imaging of a GFP-labeled mouse brain hippocampus are comparable in quality. Moreover, HiLo microscopy is capable of faster, near video rate imaging over larger fields of view than attainable with standard confocal microscopes. The goal of this paper is to advertise the simplicity, robustness, and versatility of HiLo microscopy, which we highlight with in vivo imaging of common model organisms including planaria, C. elegans, and zebrafish.

  10. Temperature dependence of the LO phonon sidebands in free exciton emission of GaN

    NASA Astrophysics Data System (ADS)

    Xu, S. J.; Li, G. Q.; Xiong, S.-J.; Che, C. M.

    2006-04-01

    Temperature-dependent radiative recombination of free excitons involving one or two LO phonons in GaN is investigated in detail. It is found that both phonon sidebands possess asymmetric lineshapes and their energy spacings from the zero-phonon line strongly deviate from the characteristic energy of LO phonons as the temperature increases. Furthermore, the deviation rates of one- and two-phonon sidebands are significantly different. Segall-Mahan [Phys. Rev. 171, 935 (1968)] theory, taking the exciton-photon and exciton-phonon interactions into account, is employed to calculate the sidebands of one or two LO phonons for free excitons in a wide temperature range. Excellent agreement between the theory and experiment is achieved by using only one adjustable parameter, which leads to determination of the effective mass of heavy holes (~0.5m0).

  11. A Study of LoRa: Long Range & Low Power Networks for the Internet of Things

    PubMed Central

    Augustin, Aloÿs; Yi, Jiazi; Clausen, Thomas; Townsley, William Mark

    2016-01-01

    LoRa is a long-range, low-power, low-bitrate, wireless telecommunications system, promoted as an infrastructure solution for the Internet of Things: end-devices use LoRa across a single wireless hop to communicate to gateway(s), connected to the Internet and which act as transparent bridges and relay messages between these end-devices and a central network server. This paper provides an overview of LoRa and an in-depth analysis of its functional components. The physical and data link layer performance is evaluated by field tests and simulations. Based on the analysis and evaluations, some possible solutions for performance enhancements are proposed. PMID:27618064

  12. Implementation and Evaluation of the Enhanced Header Compression (IPHC) for 6LoWPAN

    NASA Astrophysics Data System (ADS)

    Ludovici, Alessandro; Calveras, Anna; Catalan, Marisa; Gómez, Carles; Paradells, Josep

    6LoWPAN defines how to carry IPv6 packets over IEEE 802.15.4 low power wireless or sensor networks. Limited bandwidth, memory and energy resources require a careful application of IPv6 in a LoWPAN. The IEEE 802.15.4 standard defines a maximum frame size of 127 bytes that decreases to 102 bytes considering the header overhead. A further reduction is due to the security, network and transport protocols header overhead that, in case of IPv6 and UDP, leave only 33 bytes for application data. A compression algorithm is necessary in order to reduce the overhead and save space in data payload. This paper describes and compares the proposed IPv6 header compression mechanisms for 6LoWPAN environments.

  13. Finite-Range Separable Pairing Interaction Within New N3LO DFT Approach

    NASA Astrophysics Data System (ADS)

    Veselý, P.; Dobaczewski, J.; Michel, N.; Toivanen, J.

    2011-10-01

    For over four decades, the Skyrme functional within various parametrizations has been used to calculate nuclear properties. In the last few years there was a number of attempts to improve its performance and introduce generalized forms. In particular, the most general phenomenologi-cal quasi-local energy density functional, which contains all combinations of density, spin-density, and their derivatives up to the sixth order (N3LO), was proposed in reference [1]. Since in the phe-nomenological functional approaches the particle-particle (pp) interaction channel is treated independently from the particle-hole (ph) channel, there remains a question of what pairing interaction is suitable to use within the N3LO energy functional. In our study, we use the separable, finite-range, translationally invariant form given in [2], which we generalize to the arbitrary angular momentum channel. We discuss the application of this pairing interaction within the N3LO energy functional.

  14. A Study of LoRa: Long Range & Low Power Networks for the Internet of Things.

    PubMed

    Augustin, Aloÿs; Yi, Jiazi; Clausen, Thomas; Townsley, William Mark

    2016-09-09

    LoRa is a long-range, low-power, low-bitrate, wireless telecommunications system, promoted as an infrastructure solution for the Internet of Things: end-devices use LoRa across a single wireless hop to communicate to gateway(s), connected to the Internet and which act as transparent bridges and relay messages between these end-devices and a central network server. This paper provides an overview of LoRa and an in-depth analysis of its functional components. The physical and data link layer performance is evaluated by field tests and simulations. Based on the analysis and evaluations, some possible solutions for performance enhancements are proposed.

  15. Design and Fabrication of DebriSat - A Representative LEO Satellite for Improvements to Standard Satellite Breakup Models

    NASA Technical Reports Server (NTRS)

    Clark, S.; Dietrich, A.; Fitz-Coy, N.; Weremeyer, M.; Liou, J.-C.

    2012-01-01

    This paper discusses the design and fabrication of DebriSat, a 50 kg satellite developed to be representative of a modern low Earth orbit satellite in terms of its components, materials used, and fabrication procedures. DebriSat will be the target of a future hypervelocity impact experiment to determine the physical characteristics of debris generated after an on-orbit collision of a modern LEO satellite. The major ground-based satellite impact experiment used by DoD and NASA in their development of satellite breakup models was SOCIT, conducted in 1992. The target used for that experiment was a Navy transit satellite (40 cm, 35 kg) fabricated in the 1960's. Modern satellites are very different in materials and construction techniques than those built 40 years ago. Therefore, there is a need to conduct a similar experiment using a modern target satellite to improve the fidelity of the satellite breakup models. To ensure that DebriSat is truly representative of typical LEO missions, a comprehensive study of historical LEO satellite designs and missions within the past 15 years for satellites ranging from 1 kg to 5000 kg was conducted. This study identified modern trends in hardware, material, and construction practices utilized in recent LEO missions. Although DebriSat is an engineering model, specific attention is placed on the quality, type, and quantity of the materials used in its fabrication to ensure the integrity of the outcome. With the exception of software, all other aspects of the satellite s design, fabrication, and assembly integration and testing will be as rigorous as that of an actual flight vehicle. For example, to simulate survivability of launch loads, DebriSat will be subjected to a vibration test. As well, the satellite will undergo thermal vacuum tests to verify that the components and overall systems meet typical environmental standards. Proper assembly and integration techniques will involve comprehensive joint analysis, including the precise

  16. [The Book of the Eparch, by Leo VI: interest for the history of pharmacy].

    PubMed

    Lafont, Olivier

    2005-01-01

    In 1893, Jules Nicole discovered a greek manuscript, named Genevensis 23, which proved to be the Book of the Eparch. This document contained the regulations for trade guilds in Constantinople, at the end of the IXth century and the beginning of the Xth century. It had been published by Emperor Leo VI, who reigned upon the Byzantine Empire from 886 to 911. Three professions mentioned in this book have some interest for history of pharmacy: wax chandlers, spicers and perfumers. The differences between spicers and perfumers consisted in the kind of products they sold and in the way they weighed these products. Spicers were, at the time, far from pharmacy, because they sold mainly food and no spices, while the perfumers dealt with spices and perfumes. Anyway, none of these professions was involved in preparing medicines. No mention was made of pigmentarioi in the Book of the Eparch and that raised the question of the part really played by these so-called "pigment makers" in the preparation and the dispensation of medicines. The role of physicians remained preeminent in supplying patients with drugs.

  17. Characterization of a bioflocculant produced by a consortium of Halomonas sp. Okoh and Micrococcus sp. Leo.

    PubMed

    Okaiyeto, Kunle; Nwodo, Uchechukwu U; Mabinya, Leonard V; Okoh, Anthony I

    2013-10-16

    The physicochemical and flocculating properties of a bioflocculant produced by a bacterial consortium composed of Halomonas sp. Okoh and Micrococcus sp. Leo were investigated. The purified bioflocculant was cation and pH dependent, and optimally flocculated kaolin clay suspension at a dosage of 0.1 mg/mL. The flocculating activity of the bioflocculant was stimulated in the presence of Ca2+, Mn2+, Al3+ and had a wide pH range of 2-10, with the highest flocculating activity of 86% at pH 8. The bioflocculant was thermostable and retained more than 70% of its flocculating activity after being heated at 80 °C for 30 min. Thermogravimetric analyses revealed a partial thermal decomposition of the biofloculant at 400 °C. The infrared spectrum showed the presence of hydroxyl, carboxyl and amino moieties as functional groups. The bioflocculant produced by the bacterial consortium appears to hold promising alternative to inorganic and synthetic organic flocculants that are widely used in wastewater treatment.

  18. Characterization of a Bioflocculant Produced by a Consortium of Halomonas sp. Okoh and Micrococcus sp. Leo

    PubMed Central

    Okaiyeto, Kunle; Nwodo, Uchechukwu U.; Mabinya, Leonard V.; Okoh, Anthony I.

    2013-01-01

    The physicochemical and flocculating properties of a bioflocculant produced by a bacterial consortium composed of Halomonas sp. Okoh and Micrococcus sp. Leo were investigated. The purified bioflocculant was cation and pH dependent, and optimally flocculated kaolin clay suspension at a dosage of 0.1 mg/mL. The flocculating activity of the bioflocculant was stimulated in the presence of Ca2+, Mn2+, Al3+ and had a wide pH range of 2–10, with the highest flocculating activity of 86% at pH 8. The bioflocculant was thermostable and retained more than 70% of its flocculating activity after being heated at 80 °C for 30 min. Thermogravimetric analyses revealed a partial thermal decomposition of the biofloculant at 400 °C. The infrared spectrum showed the presence of hydroxyl, carboxyl and amino moieties as functional groups. The bioflocculant produced by the bacterial consortium appears to hold promising alternative to inorganic and synthetic organic flocculants that are widely used in wastewater treatment. PMID:24135818

  19. LEO Download Capacity Analysis for a Network of Adaptive Array Ground Stations

    NASA Technical Reports Server (NTRS)

    Ingram, Mary Ann; Barott, William C.; Popovic, Zoya; Rondineau, Sebastien; Langley, John; Romanofsky, Robert; Lee, Richard Q.; Miranda, Felix; Steffes, Paul; Mandl, Dan

    2005-01-01

    To lower costs and reduce latency, a network of adaptive array ground stations, distributed across the United States, is considered for the downlink of a polar-orbiting low earth orbiting (LEO) satellite. Assuming the X-band 105 Mbps transmitter of NASA s Earth Observing 1 (EO-1) satellite with a simple line-of-sight propagation model, the average daily download capacity in bits for a network of adaptive array ground stations is compared to that of a single 11 m dish in Poker Flats, Alaska. Each adaptive array ground station is assumed to have multiple steerable antennas, either mechanically steered dishes or phased arrays that are mechanically steered in azimuth and electronically steered in elevation. Phased array technologies that are being developed for this application are the space-fed lens (SFL) and the reflectarray. Optimization of the different boresight directions of the phased arrays within a ground station is shown to significantly increase capacity; for example, this optimization quadruples the capacity for a ground station with eight SFLs. Several networks comprising only two to three ground stations are shown to meet or exceed the capacity of the big dish, Cutting the data rate by half, which saves modem costs and increases the coverage area of each ground station, is shown to increase the average daily capacity of the network for some configurations.

  20. Ellipsoidal Space Gravity Spectrosopy By Means of Newton Interpolated Leo Ephemeris

    NASA Astrophysics Data System (ADS)

    Reubelt, T.; Austen, G.; Grafarend, E. W.

    This contribution aims at an algorithm for the orbit analysis of a Low Earth Orbiting (LEO) GPS tracked satellite to determine the ellipsoidal harmonic coefficients of the terrestrial gravitational field. The static EarthSs gravitational accelerations acting on the satellite are determined by means of the second order functional of NewtonSs in- terpolation formula and reduction from gravitational and non-gravitational disturbing forces. By means of NewtonSs Law of Motion which balances the acceleration vector with respect to an Inertial Frame of Reference (IRF) and the gradient of the gravita- tional potential, the ellipsoidal harmonics coefficients can be determined. In contrast to standard representations in terms of vector-spherical harmonics w.r.t. a reference sphere we setup the vector of gravitational field intensity in terms of vector ellipsoidal harmonics w.r.t. a reference ellipsoid. Such a representation aims at ellipsoidal space gravity spectroscopy and is for the benefit of geoid computations since the figure of the earth is fitted better by an ellipsoid. Detailed formulas and results from simulated and real CHAMP Rapid science orbits will be illustrated.

  1. Leo Szilard and the role of physicists in countering nuclear threats

    NASA Astrophysics Data System (ADS)

    Kleppner, Daniel

    2005-04-01

    Even before the first nuclear bomb was tested, Leo Szilard led efforts by physicists to assert leadership on the use of nuclear weapons. He warned about the future possibility of delivering nuclear weapons by missiles and also pointed out the ease by which nuclear bombs could simply be carried across borders. The U.S. has had an anti-ballistic missile program since the 1950's. Initially it was intended to counter a Soviet nuclear threat but with the end of the cold war the goal was changed to dealing with accidental or unauthorized launches of Russian ICBMs. More recently, the goal of the U.S. missile defense program was shifted to countering a possible future threat posed by emerging missile states. The APS Study of boost- phase intercept was carried out in the Szilard tradition of physicists providing leadership on public policy issues involving science ad technology, in the hope that factual analysis of technical problems can contribute to better public policy.

  2. Effect of LEO Exposure on Aromatic Polymers Containing Phenylphosphine Oxide Groups

    NASA Technical Reports Server (NTRS)

    Watson, K. A.; Ghose, S.; Lillehei, P. T.; Smith, J. G., Jr.; Connell, J. W.

    2007-01-01

    As part of the Materials on The International Space Station Experiment (MISSE), aromatic polymers containing phenylphosphine oxide groups were exposed to low Earth orbit (LEO) for approximately 4 years. All of the aromatic polymers containing phenylphosphine oxide groups survived the exposure despite the high fluence of atomic oxygen that completely eroded other polymer films such as Kapton and Mylar of comparable or greater thickness. The samples consisted of a colorless polyimide film and a poly(arylene ether benzimidazole) film and thread. The samples were characterized for changes in physical properties, thermal/optical properties (i.e. solar absorptivity and thermal emissivity), surface chemistry (X-ray photoelectron spectroscopy), and surface topography (atomic force microscopy). The data from the polymer samples on MISSE were compared to samples from the same batch of material stored under ambient conditions on Earth. In addition, comparisons were made between the MISSE samples and those subjected to shorter term space flight exposures. The results of these analyses will be presented.

  3. Aktiv De-Orbiting Onboard System from Leo of Upper Stages of Launchers

    NASA Astrophysics Data System (ADS)

    Trushlyakov, V.; Shalay, V.; Shatrov, J.; Jakovlev, M.; Kostantino, A.

    2009-03-01

    The active de-orbiting onboard system (VDOS) of upper separable parts (USP) stage of launchers from LEO into orbits of utilization with term of existence orbital lifetimes till 25 years is offered. ADOS it is based on use of power resources of not produced rests of liquid fuel onboard USP launchers with liquid propulsion module (LPM). Following systems enter in structure VDOS: the gas jet propulsion system consisting of a system of gasification, chambers of gas engines (GE), a control system. For gasification of the rests of liquid fuel the heat-carrier received in the autonomous gas generator is used. The gasification propellant components from each tank with temperature and the pressure determined by strength of the corresponding tank, move in chambers of the GE established on a top of a fuel compartment. After separation of a payload execute twist USP for preservation of its position in the space by activity of the GE. Ways of increase of a system effectiveness of gasification are offered by superposition on the entered heat-carrier of ultrasonic oscillations, and also introduction in gaseous fuel nanopowder of aluminum. The volume of adaptations of construction USP, connected with introduction VDOS does not exceed 5 % from weight of a dry construction.

  4. Genetic Evidence for Contrasting Wetland and Savannah Habitat Specializations in Different Populations of Lions (Panthera leo).

    PubMed

    Moore, Andy E; Cotterill, Fenton P D Woody; Winterbach, Christiaan W; Winterbach, Hanlie E K; Antunes, Agostinho; O'Brien, Stephen J

    2016-03-01

    South-central Africa is characterized by an archipelago of wetlands, which has evolved in time and space since at least the Miocene, providing refugia for animal species during Pleistocene arid episodes. Their importance for biodiversity in the region is reflected in the evolution of a variety of specialist mammal and bird species, adapted to exploit these wetland habitats. Populations of lions (Panthera leo) across south-central and east Africa have contrasting signatures of mitochondrial DNA haplotypes and biparental nuclear DNA in wetland and savannah habitats, respectively, pointing to the evolution of distinct habitat preferences. This explains the absence of genetic admixture of populations from the Kalahari savannah of southwest Botswana and the Okavango wetland of northern Botswana, despite separation by only 500 km. We postulate that ancestral lions were wetland specialists and that the savannah lions evolved from populations that were isolated during arid Pleistocene episodes. Expansion of grasslands and the resultant increase in herbivore populations during mesic Pleistocene climatic episodes provided the stimulus for the rapid population expansion and diversification of the highly successful savannah lion specialists. Our model has important implications for lion conservation.

  5. Analysing Global Achievements in Orbital Lifetime Reduction at the End of LEO Missions

    NASA Astrophysics Data System (ADS)

    Krag, Holger; Lemmens, Stijn; Flohrer, Tim; Klinkard, Heiner

    2013-08-01

    The major driver for future debris proliferation, besides the intentional and unintentional release of objects, is the abundance of objects with large masses and sizes in orbit that could be involved in catastrophic collisions. Mitigation measures thus concentrate on the prevention of object release (explosions, mission-related objects, SRM (Solid Rocket Motor) exhaust products), the disposal of objects and active collision avoidance. As ESA's simulations show, the most effective means of stabilizing the space debris environment is the removal of mass from regions with high spatial densities. A limitation of the residence time of controlled objects in altitudes below 2000km to 25 years followed by either atmospheric re-entry or reboost to higher altitudes allows to limit the growth of object numbers in the densely populated LEO environment. This is the most relevant requirement for operations. In this paper we look into the achievements of all spacefaring nations with respect to this requirement. For this purpose, ESA has developed a method to determine the operational status of running missions, by monitoring their manoeuvre activity with the help of the publicly available orbit data distributed by the US Strategic Command (USSTRATCOM). Missions that have been found to have terminated their operational life will be processed to determine the remaining orbital lifetime. The results will be presented in a statistical manner.

  6. Near-Real Time Cloud Properties and Aircraft Icing Indices from GEO and LEO Satellites

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Smith, William L., Jr.; Nguyen, Louis; Spangenberg, D. A.; Heck, Patrick W.; Palikonda, Rabindra; Ayers, J. Kirk; Wolff, Cory; Murray, John J.

    2004-01-01

    Imagers on many of the current and future operational meteorological satellites in geostationary Earth orbit (GEO) and lower Earth orbit (LEO) have enough spectral channels to derive cloud microphysical properties useful for a variety of applications. The products include cloud amount, phase, optical depth, temperature, height and pressure, thickness, effective particle size, and ice or liquid water path, shortwave albedo, and outgoing longwave radiation for each imager pixel. Because aircraft icing depends on cloud temperature, droplet size, and liquid water content as well as aircraft variables, it is possible to estimate the potential icing conditions from the cloud phase, temperature, effective droplet size, and liquid water path. A prototype icing index is currently being derived over the contiguous USA in near-real time from Geostationary Operational Environmental Satellite (GOES-10 and 12) data on a half-hourly basis and from NOAA- 16 Advanced Very High Resolution (AVHRR) data when available. Because the threshold-based algorithm is sensitive to small errors and differences in satellite imager and icing is complex process, a new probability based icing diagnosis technique is developed from a limited set of pilot reports. The algorithm produces reasonable patterns of icing probability and intensities when compared with independent model and pilot report data. Methods are discussed for improving the technique for incorporation into operational icing products.

  7. Evaluation of microsatellite markers for populations studies and forensic identification of African lions (Panthera leo).

    PubMed

    Miller, Susan M; Harper, Cindy K; Bloomer, Paulette; Hofmeyr, Jennifer; Funston, Paul J

    2014-01-01

    The South African lion (Panthera leo) population is highly fragmented. One-third of its wild lions occur in small (<1000 km(2)) reserves. These lions were reintroduced from other areas of the species' historical range. Management practices on these reserves have not prioritized genetic provenance or heterozygosity. These trends potentially constrain the conservation value of these lions. To ensure the best management and long-term survival of these subpopulations as a viable collective population, the provenance and current genetic diversity must be described. Concurrently, poaching of lions to supply a growing market for lion bones in Asia may become a serious conservation challenge in the future. Having a standardized, validated method for matching confiscated lion parts with carcasses will be a key tool in investigating these crimes. We evaluated 28 microsatellites in the African lion using samples from 18 small reserves and 1 captive facility in South Africa, two conservancies in Zimbabwe, and Kruger National and Kgalagadi Transfrontier Parks to determine the loci most suited for population management and forensic genetic applications. Twelve microsatellite loci with a match probability of 1.1×10(-5) between siblings were identified for forensics. A further 10 could be added for population genetics studies.

  8. Radiation exposure and performance of multiple burn LEO-GEO orbit transfer trajectories

    NASA Technical Reports Server (NTRS)

    Gorland, S. H.

    1985-01-01

    Many potential strategies exist for the transfer of spacecraft from low Earth orbit (LEO) to geosynchronous (GEO) orbit. One strategy has generally been utilized, that being a single impulsive burn at perigee and a GEO insertion burn at apogee. Multiple burn strategies were discussed for orbit transfer vehicles (OTVs) but the transfer times and radiation exposure, particularly for potentially manned missions, were used as arguments against those options. Quantitative results concerning the trip time and radiation encountered by multiple burn orbit transfer missions in order to establish the feasibility of manned missions, the vulnerability of electronics, and the shielding requirements are presented. The performance of these multiple burn missions is quantified in terms of the payload and propellant variances from the minimum energy mission transfer. The missions analyzed varied from one to eight perigee burns and ranged from a high thrust, 1 g, acceleration, cryogenic hydrogen-oxygen chemical propulsion system for a continuous burn, 0.001 g acceleration, hydrogen, fueled resistojet propulsion system with a trip time of 60 days.

  9. Radiation exposure and performance of multiple burn LEO-GEO orbit transfer trajectories

    NASA Technical Reports Server (NTRS)

    Gorland, S. H.

    1985-01-01

    Many potential strategies exist for the transfer of spacecraft from low Earth orbit (LEO) to geosynchronous (GEO) orbit. One strategy has generally been utilized, that being a single impulsive burn at perigee and a GEO insertion burn at apogee. Multiple burn strategies were discussed for orbit transfer vehicles (OTVs) but the transfer times and radiation exposure, particularly for potentially manned missions, were used as arguments against those options. Quantitative results concerning the trip time and radiation encountered by multiple burn orbit transfer missions in order to establish the feasibility of manned missions, the vulnerability of electronics, and the shielding requirements are presented. The performance of these multiple burn missions is quantified in terms of the payload and propellant variances from the minimum energy mission transfer. The missions analyzed varied from one to eight perigee burns and ranged from a high thrust, 1 g acceleration, cryogenic hydrogen-oxygen chemical prpulsion system to a continuous burn, 0.001 g acceleration, hydrogen fueled resistojet propulsion system with a trip time of 60 days.

  10. Fiber type and metabolic characteristics of lion (Panthera leo), caracal (Caracal caracal) and human skeletal muscle.

    PubMed

    Kohn, Tertius Abraham; Burroughs, Richard; Hartman, Marthinus Jacobus; Noakes, Timothy David

    2011-06-01

    Lion (Panthera leo) and caracal (Caracal caracal) skeletal muscle samples from Vastus lateralis, Longissimus dorsi and Gluteus medius were analyzed for fiber type and citrate synthase (CS; EC 2.3.3.1), 3-hydroxyacyl Co A dehydrogenase (3HAD; EC 1.1.1.35), phosphofructokinase-1 (PFK; EC 2.7.1.11), creatine kinase (CK; EC 2.7.3.2), phosphorylase (PHOS; EC 2.4.1.1) and lactate dehydrogenase (LDH; EC 1.1.1.27) activities and compared to human runners, the latter also serving as validation of methodology. Both felids had predominantly type IIx fibers (range 50-80%), whereas human muscle had more types I and IIa. Oxidative capacity of both felids (CS: 5-9 μmol/min/g ww and 3HAD: 1.4-2.6 μmol/min/g ww) was lower than humans, whereas the glycolytic capacity was elevated. LDH activity of caracal (346 ± 81) was higher than lion (227 ± 62 μmol/min/g ww), with human being the lowest (55 ± 17). CK and PHOS activities were also higher in caracal and lion compared to human, but PFK was lower in both felid species. The current data and past research are illustrated graphically showing a strong relationship between type II fibers and sprinting ability in various species. These data on caracal and lion muscles confirm their sprinting behavior.

  11. Head rubbing and licking reinforce social bonds in a group of captive African lions, Panthera leo.

    PubMed

    Matoba, Tomoyuki; Kutsukake, Nobuyuki; Hasegawa, Toshikazu

    2013-01-01

    Many social animals have a species-specific repertoire of affiliative behaviours that characterise individualised relationships within a group. To date, however, quantitative studies on intragroup affiliative behaviours in social carnivores have been limited. Here, we investigated the social functions of the two most commonly observed affiliative behaviours in captive African lions (Panthera leo): head rubbing and licking. We conducted behavioural observations on a captive group of lions composed of 7 males and 14 females, and tested hypotheses regarding three social functions: tension reduction, social bonding, and social status expression. Disproportionately frequent male-male and female-to-male head rubbing was observed, while more than 95% of all licking interactions occurred in female-female dyads. In accordance with the social bond hypothesis, and in disagreement with the social status expression hypothesis, both head rubbing and licking interactions were reciprocal. After controlling for spatial association, the dyadic frequency of head rubbing was negatively correlated with age difference while licking was positively correlated with relatedness. Group reunion after daily separation did not affect the frequencies of the affiliative behaviours, which was in disagreement with the predictions from the tension reduction hypothesis. These results support the social bond hypothesis for the functions of head rubbing and licking. Different patterns of affiliative behaviour between the sexes may reflect differences in the relationship quality in each sex or the differential predisposition to licking due to its original function in offspring care.

  12. Home range utilisation and territorial behaviour of lions (Panthera leo) on Karongwe Game Reserve, South Africa.

    PubMed

    Lehmann, Monika B; Funston, Paul J; Owen, Cailey R; Slotow, Rob

    2008-01-01

    Interventionist conservation management of territorial large carnivores has increased in recent years, especially in South Africa. Understanding of spatial ecology is an important component of predator conservation and management. Spatial patterns are influenced by many, often interacting, factors making elucidation of key drivers difficult. We had the opportunity to study a simplified system, a single pride of lions (Panthera leo) after reintroduction onto the 85 km(2) Karongwe Game Reserve, from 1999-2005, using radio-telemetry. In 2002 one male was removed from the paired coalition which had been present for the first three years. A second pride and male were in a fenced reserve adjacent of them to the east. This made it possible to separate social and resource factors in both a coalition and single male scenario, and the driving factors these seem to have on spatial ecology. Male ranging behaviour was not affected by coalition size, being driven more by resource rather than social factors. The females responded to the lions on the adjacent reserve by avoiding the area closest to them, therefore females may be more driven by social factors. Home range size and the resource response to water are important factors to consider when reintroducing lions to a small reserve, and it is hoped that these findings lead to other similar studies which will contribute to sound decisions regarding the management of lions on small reserves.

  13. Lion (Panthera leo) populations are declining rapidly across Africa, except in intensively managed areas.

    PubMed

    Bauer, Hans; Chapron, Guillaume; Nowell, Kristin; Henschel, Philipp; Funston, Paul; Hunter, Luke T B; Macdonald, David W; Packer, Craig

    2015-12-01

    We compiled all credible repeated lion surveys and present time series data for 47 lion (Panthera leo) populations. We used a Bayesian state space model to estimate growth rate-λ for each population and summed these into three regional sets to provide conservation-relevant estimates of trends since 1990. We found a striking geographical pattern: African lion populations are declining everywhere, except in four southern countries (Botswana, Namibia, South Africa, and Zimbabwe). Population models indicate a 67% chance that lions in West and Central Africa decline by one-half, while estimating a 37% chance that lions in East Africa also decline by one-half over two decades. We recommend separate regional assessments of the lion in the World Conservation Union (IUCN) Red List of Threatened Species: already recognized as critically endangered in West Africa, our analysis supports listing as regionally endangered in Central and East Africa and least concern in southern Africa. Almost all lion populations that historically exceeded ∼ 500 individuals are declining, but lion conservation is successful in southern Africa, in part because of the proliferation of reintroduced lions in small, fenced, intensively managed, and funded reserves. If management budgets for wild lands cannot keep pace with mounting levels of threat, the species may rely increasingly on these southern African areas and may no longer be a flagship species of the once vast natural ecosystems across the rest of the continent.

  14. Do acoustic features of lion, Panthera leo, roars reflect sex and male condition?

    PubMed

    Pfefferle, Dana; West, Peyton M; Grinnell, Jon; Packer, Craig; Fischer, Julia

    2007-06-01

    Long distance calls function to regulate intergroup spacing, attract mating partners, and/or repel competitors. Therefore, they may not only provide information about the sex (if both sexes are calling) but also about the condition of the caller. This paper provides a description of the acoustic features of roars recorded from 18 male and 6 female lions (Panthera leo) living in the Serengeti National park, Tanzania. After analyzing whether these roars differ between the sexes, tests whether male roars may function as indicators of their fighting ability or condition were conducted. Therefore, call characteristics were tested for relation to anatomical features as size, mane color, or mane length. Call characteristics included acoustic parameters that previously had been implied as indicators of size and fighting ability, e.g., call length, fundamental frequency, and peak frequency. The analysis revealed differences in relation to sex, which were entirely explained by variation in body size. No evidence that acoustic variables were related to male condition was found, indicating that sexual selection might only be a weak force modulating the lion's roar. Instead, lion roars may have mainly been selected to effectively advertise territorial boundaries.

  15. In-Orbit Lifetime Prediction for LEO and HEO Based on Orbit Determination from TLE Data

    NASA Astrophysics Data System (ADS)

    Agueda, A.; Aivar, L.; Tirado, J.; Dolado, J. C.

    2013-08-01

    Objects in Low-Earth Orbits (LEO) and Highly Elliptical Orbits (HEO) are subjected to decay and re-entry into the atmosphere due mainly to the drag force. While being this process the best solution to avoid the proliferation of debris in space and ensure the sustainability of future space activities, it implies a threat to the population on ground. Thus, the prediction of the in-orbit lifetime of an object and the evaluation of the risk on population and ground assets constitutes a crucial task. This paper will concentrate on the first of these tasks. Unfortunately the lifetime of an object in space is remarkably difficult to predict. This is mainly due to the dependence of the atmospheric drag on a number of uncertain elements such as the density profile and its dependence on the solar activity, the atmospheric conditions, the mass and surface area of the object (very difficult to evaluate), its uncontrolled attitude, etc. In this paper we will present a method for the prediction of this lifetime based on publicly available Two-Line Elements (TLEs) from the American USSTRATCOM's Joint Space Operations Center (JSpOC). TLEs constitute an excellent source to access routinely orbital information for thousands of objects even though of their reduced and unpredictable accuracy. Additionally, the implementation of the method on a CNES's Java-based tool will be presented. This tool (OPERA) is executed routinely at CNES to predict the orbital lifetime of a whole catalogue of objects.

  16. Analysis of Static Spacecraft Floating Potential at Low Earth Orbit (LEO)

    NASA Technical Reports Server (NTRS)

    Herr, Joel L.; Hwang, K. S.; Wu, S. T.

    1995-01-01

    Spacecraft floating potential is the charge on the external surfaces of orbiting spacecraft relative to the space. Charging is caused by unequal negative and positive currents to spacecraft surfaces. The charging process continues until the accelerated particles can be collected rapidly enough to balance the currents at which point the spacecraft has reached its equilibrium or floating potential. In low inclination. Low Earth Orbit (LEO), the collection of positive ion and negative electrons. in a particular direction. are typically not equal. The level of charging required for equilibrium to be established is influenced by the characteristics of the ambient plasma environment. by the spacecraft motion, and by the geometry of the spacecraft. Using the kinetic theory, a statistical approach for studying the interaction is developed. The approach used to study the spacecraft floating potential depends on which phenomena are being applied. and on the properties of the plasma. especially the density and temperature. The results from kinetic theory derivation are applied to determine the charging level and the electric potential distribution at an infinite flat plate perpendicular to a streaming plasma using finite-difference scheme.

  17. Leo Eitinger MD: tribute to a Holocaust survivor, humane physician and friend of mankind.

    PubMed

    Chelouche, Tessa

    2014-04-01

    Born in Czechoslovakia, psychiatrist Leo Eitinger (1912-1996) became internationally recognized for research on his fellow concentration camp inmates. He graduated as an MD in 1937, but being Jewish was prohibited from practicing as a doctor. When the Nazis occupied the area he was forced to flee to Norway, where in 1940 he was again deprived of his right to practice medicine. In 1942 he was arrested and deported to Auschwitz. There, as a physician inmate, he was able to help and in many cases save his fellow prisoners, not only with his medical skills but by falsifying prisoners' documents and hiding them from their Nazi captors. One of his patients was Elie Wiesel. Eitinger survived the camps but was forced to join a "death march." After the war he resumed medical practice in Norway, specializing in psychiatry. With his personal experience and knowledge of the suffering of camp survivors, he dedicated his life to studying the psychological effects of traumatic stress in different groups. Eitinger's academic contributions were crucial in the development of this area of research--namely, the effects of excessive stress, laying the foundations for the definition of post-traumatic stress disorder and the post-concentration camp syndrome, thus facilitating recognition of the medical and psychological post-war conditions of the survivors and their resultant disability pensions.

  18. Analysis of MIR-18 results for physical and biological dosimetry: radiation shielding effectiveness in LEO

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Wilson, J. W.; Williams, J. R.; Dicello, J. F.

    2000-01-01

    We compare models of radiation transport and biological response to physical and biological dosimetry results from astronauts on the Mir space station. Transport models are shown to be in good agreement with physical measurements and indicate that the ratio of equivalent dose from the Galactic Cosmic Rays (GCR) to protons is about 3/2:1 and that this ratio will increase for exposures to internal organs. Two biological response models are used to compare to the Mir biodosimetry for chromosome aberration in lymphocyte cells; a track-structure model and the linear-quadratic model with linear energy transfer (LET) dependent weighting coefficients. These models are fit to in vitro data for aberration formation in human lymphocytes by photons and charged particles. Both models are found to be in reasonable agreement with data for aberrations in lymphocytes of Mir crew members: however there are differences between the use of LET dependent weighting factors and track structure models for assigning radiation quality factors. The major difference in the models is the increased effectiveness predicted by the track model for low charge and energy ions with LET near 10 keV/micrometers. The results of our calculations indicate that aluminum shielding, although providing important mitigation of the effects of trapped radiation, provides no protective effect from the galactic cosmic rays (GCR) in low-earth orbit (LEO) using either equivalent dose or the number of chromosome aberrations as a measure until about 100 g/cm 2 of material is used.

  19. Extreme ultraviolet emission from laser-induced plasma relevance to neutral gas environment simulation in LEO

    NASA Astrophysics Data System (ADS)

    Tagawa, Masahito; Kimoto, Yugo; Yokota, Kumiko; Ohira, Junki; Watanabe, Daiki; Nishimura, Hiroaki

    The reaction mechanism of atomic oxygen (AO) in low Earth orbit (LEO) with spacecraft materials has been studied by ground-based experiments using laser-detonation hyperthermal beam source, which enables to accelerate the electrically neutral AO up to 8 km/s. However, the beam conditions in the laser-detonation sources could not fully duplicate the AO environment in space. The difference in beam condition including side products leads to the different material responses. The light emission from the laser-induced oxygen plasma may affect the erosion of ultraviolet (UV)-sensitive materials. However, the light emission could also be used as a diagnostic tool to understand the molecular processes in plasma. In this presentation, extreme ultraviolet (EUV) emission from the laser-induced plasma during AO test was evaluated by the flat field EUV spectrometer. Many emission lines between 25-40 nm originated from OII and OIII were observed from the laser-induced oxygen plasma. This result suggested multiple-charged O ions are generated in the laser-induced plasma. Promotion of oxygen dissociation effect by adding Ar in the target gas was explained by the energy transfer processes from Ar to O2 in the plasma. From the viewpoint of reducing the side products in the AO exposure tests, a method to reduce the EUV emission will also be investigated. These results could be used for establishing more accurate ground-based natural gas simulations on the space environmental effect of materials.

  20. A serosurvey of viral infections in lions (Panthera leo), from Queen Elizabeth National Park, Uganda.

    PubMed

    Driciru, Margaret; Siefert, Ludwig; Prager, Katherine C; Dubovi, Edward; Sande, Robert; Princee, Frank; Friday, Tom; Munson, Linda

    2006-07-01

    Serum samples from 14 lions (Panthera leo) from Queen Elizabeth National Park, Uganda, were collected during 1998 and 1999 to determine infectious disease exposure in this threatened population. Sera were analyzed for antibodies against feline immunodeficiency virus (FIV), feline calicivirus (FCV), feline herpesvirus 1 (feline rhinotracheitis: FHV1), feline/canine parvovirus (FPV/CPV), feline infectious peritonitis virus (feline coronavirus: FIPV), and canine distemper virus (CDV) or for the presence of feline leukemia virus (FeLV) antigens. Ten lions (71%) had antibodies against FIV, 11 (79%) had antibodies against CDV, 11 (79%) had antibodies against FCV, nine (64%) had antibodies against FHV1, and five (36%) had antibodies against FPV. Two of the 11 CDV-seropositive lions were subadults, indicating recent exposure of this population to CDV or a CDV-like virus. No lions had evidence of exposure to FeLV or FIPV. These results indicate that this endangered population has extensive exposure to common feline and canine viruses.

  1. Model-Based GN and C Simulation and Flight Software Development for Orion Missions beyond LEO

    NASA Technical Reports Server (NTRS)

    Odegard, Ryan; Milenkovic, Zoran; Henry, Joel; Buttacoli, Michael

    2014-01-01

    For Orion missions beyond low Earth orbit (LEO), the Guidance, Navigation, and Control (GN&C) system is being developed using a model-based approach for simulation and flight software. Lessons learned from the development of GN&C algorithms and flight software for the Orion Exploration Flight Test One (EFT-1) vehicle have been applied to the development of further capabilities for Orion GN&C beyond EFT-1. Continuing the use of a Model-Based Development (MBD) approach with the Matlab®/Simulink® tool suite, the process for GN&C development and analysis has been largely improved. Furthermore, a model-based simulation environment in Simulink, rather than an external C-based simulation, greatly eases the process for development of flight algorithms. The benefits seen by employing lessons learned from EFT-1 are described, as well as the approach for implementing additional MBD techniques. Also detailed are the key enablers for improvements to the MBD process, including enhanced configuration management techniques for model-based software systems, automated code and artifact generation, and automated testing and integration.

  2. Selected clinical, biochemical, and electrolyte alterations in anesthetized captive tigers (Panthera tigris) and lions (Panthera leo).

    PubMed

    Reilly, Sabrina; Seddighi, M Reza; Steeil, James C; Sura, Patricia; Whittemore, Jacqueline C; Gompf, Rebecca E; Elliott, Sarah B; Ramsay, Edward C

    2014-06-01

    A prospective study to assess changes in selected plasma biochemistry and electrolyte values, plasma insulin and aldosterone concentrations, and electrocardiography (ECG) was performed on eight female captive tigers (Panthera tigris) and three lions (Panthera leo) undergoing general anesthesia for elective laparoscopic ovariectomy. Each animal was sedated with medetomidine (18-25 microg/kg) and midazolam (0.06-0.1 mg/kg) intramuscularly, and anesthesia was induced with ketamine (1.9-3.5 mg/kg) intramuscularly and maintained with isoflurane. Venous blood samples were collected and analyzed for plasma biochemistry parameters and insulin and aldosterone concentrations. An ECG was recorded at the time of each blood sample collection. Mean plasma potassium, glucose, phosphorus, and aldosterone concentrations increased during anesthesia (P < or = 0.05). One tiger developed hyperkalemia (6.5 mmol/L) 2.5 hr after anesthetic induction. Plasma insulin concentrations were initially below the low end of the domestic cat reference interval (72-583 pmol/L), but mean insulin concentration increased (P < or = 0.05) over time compared with the baseline values. Three tigers and two lions had ECG changes that were representative of myocardial hypoxemia. Based on these results, continuous monitoring of clinical and biochemical alterations during general anesthesia in large nondomestic felids is warranted, and consideration should be given to reversal of medetomidine in these animals should significant changes in electrolytes or ECG occur.

  3. ALFALFA and WSRT Imaging of Extended H I Features in the Leo Cloud of Galaxies

    NASA Astrophysics Data System (ADS)

    Leisman, Lukas; Haynes, Martha P.; Giovanelli, Riccardo; Józsa, Gyula; Adams, Elizabeth A. K.; Hess, Kelley M.

    2016-12-01

    We present Arecibo Legacy Fast ALFA (ALFALFA) H I observations of a well-studied region of the Leo Cloud, which includes the NGC 3227 group and the NGC 3190 group. We detect optically dark H I tails and plumes with extents potentially exceeding 600 kpc, well beyond the field of view of previous observations. These H I features contain ˜40 per cent of the total H I mass in the NGC 3227 group and ˜10 per cent of the NGC 3190 group. We also present Westerbork Synthesis Radio Telescope (WSRT) maps which show the complex morphology of the extended emission in the NGC 3227 group. We comment on previously proposed models of the interactions in these groups and the implications for the scale of group processing through interactions. Motivated by the extent of the H I plumes, we place the H I observations in the context of the larger loose group, demonstrating the need for future sensitive, wide field H I surveys to understand the role of group processing in galaxy evolution.

  4. Relative clock estimation method between two LEO satellites with a double-difference solution constraint

    NASA Astrophysics Data System (ADS)

    Liu, Junhong; Gu, Defeng; Ju, Bing; Lai, Yuwang; Yi, Dongyun

    2015-04-01

    A method of estimating the relative clocks between two spaceborne global positioning system (GPS) receivers based on the single-difference (SD) observations is investigated in this paper. Especially, the advantages of introducing a double-difference (DD) solution constraint, including the orbits and ambiguities, are discussed with the simulated data and the real data of Gravity Recovery And Climate Experiment (GRACE) satellites. The theoretical accuracy analysis shows that the accuracy of the relative clocks is improved and the edge effects are eliminated with a DD solution constraint. The simulations indicate a potential accuracy improvement of at least 30% of the relative clocks with the constraint. Furthermore, one month's real data is processed and the overlapping data arcs are used to validate the accuracy of the relative clock solutions. The average overlapping root mean square (RMS) of the relative clock solutions is approximate 99 ps and 31 ps without and with the DD solution constraint, respectively. Moreover, the jumps of the day boundaries are weakened evidently by adding the DD solution constraint. This paper demonstrates that the accuracy and stability of the estimated relative clocks between two low earth orbit (LEO) satellites from SD observations are improved obviously with the DD solution constraint.

  5. Lions (Panthera leo) solve, learn, and remember a novel resource acquisition problem.

    PubMed

    Borrego, Natalia; Dowling, Brian

    2016-09-01

    The social intelligence hypothesis proposes that the challenges of complex social life bolster the evolution of intelligence, and accordingly, advanced cognition has convergently evolved in several social lineages. Lions (Panthera leo) offer an ideal model system for cognitive research in a highly social species with an egalitarian social structure. We investigated cognition in lions using a novel resource task: the suspended puzzle box. The task required lions (n = 12) to solve a novel problem, learn the techniques used to solve the problem, and remember techniques for use in future trials. The majority of lions demonstrated novel problem-solving and learning; lions (11/12) solved the task, repeated success in multiple trials, and significantly reduced the latency to success across trials. Lions also demonstrated cognitive abilities associated with memory and solved the task after up to a 7-month testing interval. We also observed limited evidence for social facilitation of the task solution. Four of five initially unsuccessful lions achieved success after being partnered with a successful lion. Overall, our results support the presence of cognition associated with novel problem-solving, learning, and memory in lions. To date, our study is only the second experimental investigation of cognition in lions and further supports expanding cognitive research to lions.

  6. Ultrasonographic and laparoscopic evaluation of the reproductive tract of the captive female African lion (Panthera leo).

    PubMed

    Kirberger, Robert M; Schulman, Martin L; Hartman, Marthinus J

    2011-09-15

    The use of transabdominal ultrasonography to assess the oestrous cycle has not been previously described in the African lion (Panthera leo). Twelve sexually mature lionesses and five female cubs had their reproductive organs assessed by transabdominal ultrasound. Ovarian findings were compared to laparoscopic findings while performing laparoscopic ovariectomy or salpingectomy. Vaginal cytology was performed and serum progesterone levels were determined. By combining all data the oestrous cycle stage of each lion was determined. One lion was far pregnant and was not operated on. In adults a uterine body could be seen ultrasonographically in 67% of lions while mural structures could be distinguished in 44% of lions. Five uterine horns could be seen in 3 lions. In 12 adults 10 ovaries were found of which eight had discernable follicles or luteal structures. During laparoscopy 12 active ovaries were seen with luteal structures seen in 11 ovaries and follicles in 2 ovaries. Using laparoscopy as the gold standard, ultrasonography had a sensitivity of 66% and specificity of 83% to detect ovarian reproductive activity. Two uterine cysts and a cluster of periovarian cysts were seen in three different lions. Three lions were pregnant, two were in oestrus, three in a luteal phase (dioestrus), and four were in anoestrus. Transabdominal ultrasound in combination with serum progesterone levels and vaginal cytology can be used to assess ovarian cyclical activity with reasonable accuracy in captive bred lions.

  7. Diagnosis and treatment of a dermal malignant melanoma in an African lion (Panthera leo).

    PubMed

    Steeil, James C; Schumacher, Juergen; Baine, Katherine; Ramsay, Edward C; Sura, Patricia; Hodshon, Rebecca; Donnell, Robert L; Lee, Nathan D

    2013-09-01

    A 13-yr-old intact male African lion (Panthera leo) presented with a 4-mo history of left maxillary lip swelling. On physical examination, a 10-cm-diameter, ulcerated, round, firm, and pigmented mass at the level of the left maxillary canine tooth was noticed. All other organ systems examined were within normal limits. Multiple biopsies of the mass were collected and fixed in 10% neutral buffered formalin. Histopathologic evaluation of the biopsies revealed a malignant dermal melanoma. Hematologic and plasma biochemical parameters were within normal reference ranges. Thoracic radiographs taken 3 days following initial presentation showed no evidence of metastasis of the tumor. Computed tomography of the skull and neck was performed to evaluate local tumor invasion and to plan for hypofractionated radiation therapy. Therapy included four weekly treatments of 8 gray external-beam hypofractionated radiation and four bimonthly immunotherapy treatments. Following this treatment regime, the tumor size was reduced by 50%, and surgical excision was performed. No major side effects associated with radiation or immunotherapy were seen. Six months after diagnosis, hematologic and plasma biochemical parameters were within normal limits, thoracic radiographs showed no evidence of metastasis, and the lion showed no clinical signs of disease. The lion will continue to receive immunotherapy every 6 mo for the rest of its life. To the authors' knowledge, this is the first report of a successful treatment of a malignant dermal melanoma with external-beam hypofractionated radiation, immunotherapy, and surgical excision in an African lion.

  8. Mycobacterium bovis infection in the lion (Panthera leo): Current knowledge, conundrums and research challenges.

    PubMed

    Viljoen, Ignatius M; van Helden, Paul D; Millar, Robert P

    2015-06-12

    Mycobacterium bovis has global public-health and socio-economic significance and can infect a wide range of species including the lion (Panthera leo) resulting in tuberculosis. Lions are classified as vulnerable under the IUCN Red List of Threatened Species and have experienced a 30% population decline in the past two decades. However, no attempt has been made to collate and critically evaluate the available knowledge of M. bovis infections in lions and potential effects on population. In this review we set out to redress this. Arguments suggesting that ingestion of infected prey animals are the main route of infection for lions have not been scientifically proven and research is needed into other possible sources and routes of infection. The paucity of knowledge on host susceptibility, transmission directions and therefore host status, manifestation of pathology, and epidemiology of the disease in lions also needs to be addressed. Advances have been made in diagnosing the presence of M. bovis in lions. However, these diagnostic tests are unable to differentiate between exposure, presence of infection, or stage of disease. Furthermore, there are contradictory reports on the effects of M. bovis on lion populations with more data needed on disease dynamics versus the lion population's reproductive dynamics. Knowledge on disease effects on the lion reproduction and how additional stressors such as drought or co-morbidities may interact with tuberculosis is also lacking. Filling these knowledge gaps will contribute to the understanding of mycobacterial infections and disease in captive and wild lions and assist in lion conservation endeavours.

  9. A Low-Noise Terahertz SIS Mixer Incorporating a Waveguide Directional Coupler for LO Injection

    NASA Astrophysics Data System (ADS)

    Kojima, Takafumi; Kuroiwa, Kouichi; Uzawa, Yoshinori; Kroug, Matthias; Takeda, Masanori; Fujii, Yasunori; Kaneko, Keiko; Miyachi, Akihira; Wang, Zhen; Ogawa, Hideo

    2010-11-01

    We have developed a low-noise heterodyne waveguide Superconductor-Insulator-Superconductor (SIS) mixer with a novel local oscillator (LO) injection scheme for the Atacama Large Millimeter/submillimeter Array (ALMA) band 10, over the frequency range 0.78-0.95 THz. The SIS mixer uses radio frequency (RF) and LO receiving horns separately and a waveguide 10 dB LO coupler integrated in the mixer block. The insertion loss of the waveguide and coupling factor of the coupler were evaluated at terahertz frequencies at both room and cryogenic temperatures. The double-sideband (DSB) receiver noise temperatures were below 330 K (7.5 hf/ k B) at LO frequencies in the range 0.801-0.945 THz. The minimum temperature was 221 K at 0.873 THz over the intermediate frequency range of 4-12 GHz at an operating temperature of 4 K. This waveguide heterodyne SIS mixer exhibits great potential for practical applications, such as high-frequency receivers of the ALMA.

  10. Structural Validity of the Professional Development Profile of the LoTi Digital-Age Survey

    ERIC Educational Resources Information Center

    Mehta, Vandhana; Hull, Darrell M.

    2013-01-01

    The present study was used to examine the structural construct validity of the Professional Development Profile of the LoTi Digital-Age Survey, a measure of teacher instructional practices with technology in the classroom. Teacher responses ("N" = 2,840) from across the United States were used to assess factor structure of the instrument…

  11. The Karhunen-Loève Transform for bioastronomy and SETI

    NASA Astrophysics Data System (ADS)

    Maccone, C.

    2006-02-01

    I present here a short description of the Karhunen-Loève Transform (KLT) used to detect very weak radio signals over narrow-band and wide-band extraterrestrial telecommunications out of the cosmic background noise. It appears that the KLT is more appropriate than the well known Fourier Transform (FT).

  12. A Simultaneous Discovery: The Case of Johannes Stark and Antonino Lo Surdo

    NASA Astrophysics Data System (ADS)

    Leone, Matteo; Paoletti, Alessandro; Robotti, Nadia

    2004-09-01

    In 1913 the German physicist Johannes Stark (1874 1957) and the Italian physicist Antonino Lo Surdo (1880 1949)discovered virtually simultaneously and independently that hydrogen spectral lines are split into components by an external electric field. Both of their discoveries ensued from studies on the same phenomenon, the Doppler effect in canal rays, but they arose in different theoretical contexts. Stark had been working within the context of the emerging quantum theory, following a research program aimed at studying the effect of an electric field on spectral lines. Lo Surdo had been working within the context of the classical theory, and his was an accidental discovery. Both discoveries, however, played important roles in the history of physics: Stark’s discovery contributed to the establishment of both the old and the new quantum theories; Lo Surdo’s discovery led Antonio Garbasso (1871 1933)to introduce research on the quantum theory into Italian physics. Ironically, soon after their discoveries, both Stark and Lo Surdo rejected developments in modern physics and allied themselves with the political and racial programs of Hitler and Mussolini.

  13. Numerical Investigation of LO2 and LCH4 Storage Tanks on the Lunar Surface

    NASA Technical Reports Server (NTRS)

    Moder, Jeff; Barsi, Stephen; Kassemi, Mohammad

    2008-01-01

    Currently NASA is developing technologies to enable human exploration of the lunar surface for duration of up to 210 days. While trade studies are still underway, a cryogenic ascent stage using liquid oxygen (LO2) and liquid methane (LCH4) is being considered for the Altair lunar lander. For a representative Altair cryogenic ascent stage, we present a detailed storage analysis of the LO2 and LCH4 propellant tanks on the lunar surface for durations of up to 210 days. Both the LO2 and LCH4 propellant tanks are assumed to be pressurized with gaseous helium at launch. A two-phase lumped-vapor computational fluid dynamics model has been developed to account for the presence of a noncondensable gas in the ullage. The CFD model is used to simulate the initial pressure response of the propellant tanks while they are subjected to representative heat leak rates on the lunar surface. Once a near stationary state is achieved within the liquid phase, multizone model is used to extrapolate the solution farther in time. For fixed propellant mass and tank size, the long-term pressure response for different helium mass fractions in both the LO2 and LCH4 tanks is examined.

  14. Forwarding techniques for IP fragmented packets in a real 6LoWPAN network.

    PubMed

    Ludovici, Alessandro; Calveras, Anna; Casademont, Jordi

    2011-01-01

    Wireless Sensor Networks (WSNs) are attracting more and more interest since they offer a low-cost solution to the problem of providing a means to deploy large sensor networks in a number of application domains. We believe that a crucial aspect to facilitate WSN diffusion is to make them interoperable with external IP networks. This can be achieved by using the 6LoWPAN protocol stack. 6LoWPAN enables the transmission of IPv6 packets over WSNs based on the IEEE 802.15.4 standard. IPv6 packet size is considerably larger than that of IEEE 802.15.4 data frame. To overcome this problem, 6LoWPAN introduces an adaptation layer between the network and data link layers, allowing IPv6 packets to be adapted to the lower layer constraints. This adaptation layer provides fragmentation and header compression of IP packets. Furthermore, it also can be involved in routing decisions. Depending on which layer is responsible for routing decisions, 6LoWPAN divides routing in two categories: mesh under if the layer concerned is the adaptation layer and route over if it is the network layer. In this paper we analyze different routing solutions (route over, mesh under and enhanced route over) focusing on how they forward fragments. We evaluate their performance in terms of latency and energy consumption when transmitting IP fragmented packets. All the tests have been performed in a real 6LoWPAN implementation. After consideration of the main problems in forwarding of mesh frames in WSN, we propose and analyze a new alternative scheme based on mesh under, which we call controlled mesh under.

  15. XYZ-like spectra from Laplace sum rule at N2LO in the chiral limit

    NASA Astrophysics Data System (ADS)

    Albuquerque, R.; Narison, S.; Fanomezana, F.; Rabemananjara, A.; Rabetiarivony, D.; Randriamanatrika, G.

    2016-12-01

    We present new compact integrated expressions of QCD spectral functions of heavy-light molecules and four-quark XY Z-like states at lowest order (LO) of perturbative (PT) QCD and up to d = 8 condensates of the Operator Product Expansion (OPE). Then, by including up to next-to-next leading order (N2LO) PT QCD corrections, which we have estimated by assuming the factorization of the four-quark spectral functions, we improve previous LO results from QCD spectral sum rules (QSSR), on the XY Z-like masses and decay constants which suffer from the ill-defined heavy quark mass. PT N3LO corrections are estimated using a geometric growth of the PT series and are included in the systematic errors. Our optimal results based on stability criteria are summarized in Tables 11-14 and compared, in Sec. 10, with experimental candidates and some LO QSSR results. We conclude that the masses of the XZ observed states are compatible with (almost) pure JPC = 1+±, 0++ molecule or/and four-quark states. The ones of the 1-±, 0-± molecule/four-quark states are about 1.5 GeV above the Yc,b mesons experimental candidates and hadronic thresholds. We also find that the couplings of these exotics to the associated interpolating currents are weaker than that of ordinary D,B mesons (fDD ≈ 10-3f D) and may behave numerically as 1/m¯b3/2 (respectively 1/m¯b) for the 1+, 0+ (respectively 1-, 0-) states which can stimulate further theoretical studies of these decay constants.

  16. Addressing challenges in combining GOES and LEO satellite products of the CONUS

    NASA Astrophysics Data System (ADS)

    Petersen, R. A.; Dworak, R.

    2012-12-01

    The challenges of transforming data from the next generation of satellites into information and products for the weather and science purposes presents a major challenge to both the research and applications communities. This will be especially difficult over land, where the process of integrating observations from multiple instruments and platforms in real time is complicated by the influence of the land surface on the observations themselves. In addition, effective merging of the mixture of time-continuous GEO and less frequent but higher spectral resolution LEO observations with other new surface-based observations will be essential and require new product processing strategies. The material shown in this presentation will begin to address some of these issues. It will describe results of efforts to inter-calibrate moisture products derived from existing GEO and LEO data sets over land designed 1) to identify and remove biases from the GOES moisture retrievals, 2) to determine the seasonally varying information content of the GOES relative to NWP model 'first guess' fields, 3) to determine the similarities and differences in error structures between GOES and AIRS retrievals, and 4) to determine the vertical structure of the errors in both systems. For example, comparisons have been made between GOES Total Precipitable Water (TPW) using the Li retrieval system (GOES-Li) and data from Raman Lidar (RL), Microwave Radiometer (MWR) and surface-based GPS-Met systems at the ARM CART site. The test showed for using one year of derived TPW products, the NWP model first guess (GFS) and GOES-Li products are wetter, however the GOES-Li beats the GFS in the warm season, especially in August when the NWP precipitation skill is least. During the warm season GOES-Li is noticeably better than GFS (which was too wet) during daytime. In addition, the GPS-Met data are best during the daytime, while the Ramon Lidar performs best at night. AIRS products were also evaluated for several

  17. Operational Impact of Improved Space Tracking on Collision Avoidance in the Future LEO Space Debris Environment

    NASA Astrophysics Data System (ADS)

    Sibert, D.; Borgeson, D.; Peterson, G.; Jenkin, A.; Sorge, M.

    2010-09-01

    Even if global space policy successfully curtails on orbit explosions and ASAT demonstrations, studies indicate that the number of debris objects in Low Earth Orbit (LEO) will continue to grow solely from debris on debris collisions and debris generated from new launches. This study examines the threat posed by this growing space debris population over the next 30 years and how improvements in our space tracking capabilities can reduce the number of Collision Avoidance (COLA) maneuvers required keep the risk of operational satellite loss within tolerable limits. Particular focus is given to satellites operated by the Department of Defense (DoD) and Intelligence Community (IC) in Low Earth Orbit (LEO). The following debris field and space tracking performance parameters were varied parametrically in the experiment to study the impact on the number of collision avoidance maneuvers required: - Debris Field Density (by year 2009, 2019, 2029, and 2039) - Quality of Track Update (starting 1 sigma error ellipsoid) - Future Propagator Accuracy (error ellipsoid growth rates - Special Perturbations in 3 axes) - Track Update Rate for Debris (stochastic) - Track Update Rate for Payloads (stochastic) Baseline values matching present day tracking performance for quality of track update, propagator accuracy, and track update rate were derived by analyzing updates to the unclassified Satellite Catalog (SatCat). Track update rates varied significantly for active payloads and debris and as such we used different models for the track update rates for military payloads and debris. The analysis was conducted using the System Effectiveness Analysis Simulation (SEAS) an agent based model developed by the United States Air Force Space Command’s Space and Missile Systems Center to evaluate the military utility of space systems. The future debris field was modeled by The Aerospace Corporation using a tool chain which models the growth of the 10cm+ debris field using high fidelity

  18. Neurologic Disease in Captive Lions (Panthera leo) with Low-Titer Lion Lentivirus Infection▿

    PubMed Central

    Brennan, Greg; Podell, Michael D.; Wack, Raymund; Kraft, Susan; Troyer, Jennifer L.; Bielefeldt-Ohmann, Helle; VandeWoude, Sue

    2006-01-01

    Lion lentivirus (LLV; also known as feline immunodeficiency virus of lion, Panthera leo [FIVPle]) is present in free-ranging and captive lion populations at a seroprevalence of up to 100%; however, clinical signs are rarely reported. LLV displays up to 25% interclade sequence diversity, suggesting that it has been in the lion population for some time and may be significantly host adapted. Three captive lions diagnosed with LLV infection displayed lymphocyte subset alterations and progressive behavioral, locomotor, and neuroanatomic abnormalities. No evidence of infection with other potential neuropathogens was found. Antemortem electrodiagnostics and radiologic imaging indicated a diagnosis consistent with lentiviral neuropathy. PCR was used to determine a partial lentiviral genomic sequence and to quantify the proviral burden in eight postmortem tissue specimens. Phylogenetic analysis demonstrated that the virus was consistent with the LLV detected in other captive and free-ranging lions. Despite progressive neurologic signs, the proviral load in tissues, including several regions of the brain, was low; furthermore, gross and histopathologic changes in the brain were minimal. These findings suggest that the symptoms in these animals resulted from nonspecific encephalopathy, similar to human immunodeficiency virus, FIV, and simian immunodeficiency virus (SIV) neuropathies, rather than a direct effect of active viral replication. The association of neuropathy and lymphocyte subset alterations with chronic LLV infection suggests that long-term LLV infection can have detrimental effects for the host, including death. This is similar to reports of aged sootey mangabeys dying from diseases typically associated with end-stage SIV infection and indicates areas for further research of lentiviral infections of seemingly adapted natural hosts, including mechanisms of host control and viral adaptation. PMID:17005739

  19. Comparative Skull Analysis Suggests Species-Specific Captivity-Related Malformation in Lions (Panthera leo)

    PubMed Central

    Saragusty, Joseph; Shavit-Meyrav, Anat; Yamaguchi, Nobuyuki; Nadler, Rona; Bdolah-Abram, Tali; Gibeon, Laura; Hildebrandt, Thomas B.; Shamir, Merav H.

    2014-01-01

    Lion (Panthera leo) populations have dramatically decreased worldwide with a surviving population estimated at 32,000 across the African savannah. Lions have been kept in captivity for centuries and, although they reproduce well, high rates of stillbirths as well as morbidity and mortality of neonate and young lions are reported. Many of these cases are associated with bone malformations, including foramen magnum (FM) stenosis and thickened tentorium cerebelli. The precise causes of these malformations and whether they are unique to captive lions remain unclear. To test whether captivity is associated with FM stenosis, we evaluated 575 lion skulls of wild (N = 512) and captive (N = 63) origin. Tiger skulls (N = 276; 56 captive, 220 wild) were measured for comparison. While no differences were found between males and females or between subadults and adults in FM height (FMH), FMH of captive lions (17.36±3.20 mm) was significantly smaller and with greater variability when compared to that in wild lions (19.77±2.11 mm). There was no difference between wild (18.47±1.26 mm) and captive (18.56±1.64 mm) tigers in FMH. Birth origin (wild vs. captive) as a factor for FMH remained significant in lions even after controlling for age and sex. Whereas only 20/473 wild lions (4.2%) had FMH equal to or smaller than the 5th percentile of the wild population (16.60 mm), this was evident in 40.4% (23/57) of captive lion skulls. Similar comparison for tigers found no differences between the captive and wild populations. Lions with FMH equal to or smaller than the 5th percentile had wider skulls with smaller cranial volume. Cranial volume remained smaller in both male and female captive lions when controlled for skull size. These findings suggest species- and captivity-related predisposition for the pathology in lions. PMID:24718586

  20. The evolutionary dynamics of the lion Panthera leo revealed by host and viral population genomics.

    PubMed

    Antunes, Agostinho; Troyer, Jennifer L; Roelke, Melody E; Pecon-Slattery, Jill; Packer, Craig; Winterbach, Christiaan; Winterbach, Hanlie; Hemson, Graham; Frank, Laurence; Stander, Philip; Siefert, Ludwig; Driciru, Margaret; Funston, Paul J; Alexander, Kathy A; Prager, Katherine C; Mills, Gus; Wildt, David; Bush, Mitch; O'Brien, Stephen J; Johnson, Warren E

    2008-11-01

    The lion Panthera leo is one of the world's most charismatic carnivores and is one of Africa's key predators. Here, we used a large dataset from 357 lions comprehending 1.13 megabases of sequence data and genotypes from 22 microsatellite loci to characterize its recent evolutionary history. Patterns of molecular genetic variation in multiple maternal (mtDNA), paternal (Y-chromosome), and biparental nuclear (nDNA) genetic markers were compared with patterns of sequence and subtype variation of the lion feline immunodeficiency virus (FIV(Ple)), a lentivirus analogous to human immunodeficiency virus (HIV). In spite of the ability of lions to disperse long distances, patterns of lion genetic diversity suggest substantial population subdivision (mtDNA Phi(ST) = 0.92; nDNA F(ST) = 0.18), and reduced gene flow, which, along with large differences in sero-prevalence of six distinct FIV(Ple) subtypes among lion populations, refute the hypothesis that African lions consist of a single panmictic population. Our results suggest that extant lion populations derive from several Pleistocene refugia in East and Southern Africa ( approximately 324,000-169,000 years ago), which expanded during the Late Pleistocene ( approximately 100,000 years ago) into Central and North Africa and into Asia. During the Pleistocene/Holocene transition ( approximately 14,000-7,000 years), another expansion occurred from southern refugia northwards towards East Africa, causing population interbreeding. In particular, lion and FIV(Ple) variation affirms that the large, well-studied lion population occupying the greater Serengeti Ecosystem is derived from three distinct populations that admixed recently.

  1. Multiwavelength Optical Observations of Two Chromospherically Active Binary Systems: V789 Mon and GZ Leo

    NASA Astrophysics Data System (ADS)

    Gálvez, M. C.; Montes, D.; Fernández-Figueroa, M. J.; De Castro, E.; Cornide, M.

    2009-04-01

    This paper describes a multiwavelength optical study of chromospheres in two X-ray/EUV-selected active binary stars with strong Hα emission, V789 Mon (2RE J0725 - 002) and GZ Leo (2RE J1101+223). The goal of the study is to determine radial velocities and fundamental stellar parameters in chromospherically active binary systems in order to include them in the activity-rotation and activity-age relations. We carried out high-resolution echelle spectroscopic observations and applied spectral-subtraction technique in order to measure emission excesses due to chromosphere. The detailed study of activity indicators allowed us to characterize the presence of different chromospheric features in these systems and enabled to include them in a larger activity-rotation survey. We computed radial velocities of the systems using cross-correlation with the radial velocity standards. The double-line spectral binarity was confirmed and the orbital solutions improved for both systems. In addition, other stellar parameters such as spectral types, projected rotational velocities (vsin i) and the equivalent width of the lithium Li I λ6707.8 Å absorption line were determined. Based on observations collected with the 2.2 m telescope at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto (Almería, Spain), operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC) and with the 2.1 m Otto Struve Telescope at McDonald Observatory of the University of Texas at Austin (USA).

  2. Electrocardiographic parameters of captive lions (Panthera leo) and tigers (Panthera tigris) immobilized with ketamine plus xylazine.

    PubMed

    Larsson, Maria Helena M A; Coelho, Fernanda M; Oliveira, Valéria M C; Yamaki, Fernanda L; Pereira, Guilherme G; Soares, Elaine C; Fedullo, José Daniel L; Pereira, Roberto C; Ito, F H

    2008-09-01

    Twenty-seven healthy captive lions (Panthera leo) and 13 healthy captive tigers (Panthera tigris) from São Paulo Zoo (Fundação Parque Zoológico de Sã Paulo, São Paulo, Brazil) collection were selected for this study. They were anesthetized with ketamine (10 mg/kg) combined with xylazine (1-2 mg/kg) for physical examinations, hematologic and serum chemical analysis and electrocardiogram recording. The main aim of this research was to gather initial information about normal electrocardiographic parameters of large felids. Standard P-QRS-T deflections on leads described for domestic carnivores were analyzed, and they did not greatly differ from those of large felids, taking into account the greater weight and corporal mass of large felids. Heart rate of lions ranged from 42 to 76 beats per minute (bpm). Heart rate of tigers ranged from 56 to 97 bpm. In both species, the most common rhythm detected was normal sinus rhythm followed by sinus arrhythmia; wandering pacemaker was also observed with normal sinus rhythm or sinus arrhythmia. Mean electrical axis lay between +60 degrees and +120 degrees. QRS complexes were predominantly positive in leads DI, DII, DIII, and AVF, and negative in AVR and AVL. This study provides insights into normal electrocardiograms of large felids. Wider investigations on the same subject are necessary to establish criteria for the recognition of abnormalities in these species and should include other anesthetic drug(s) combinations and reports of electrocardiographic features of animals with cardiac disease and electrolytes disturbances.

  3. Reversible anaesthesia of free-ranging lions (Panthera leo) in Zimbabwe.

    PubMed

    Fahlman, A; Loveridge, A; Wenham, C; Foggin, C; Arnemo, J M; Nyman, G

    2005-12-01

    The combination of medetomidine-zolazepam-tiletamine with subsequent antagonism by atipamezole was evaluated for reversible anaesthesia of free-ranging lions (Panthera leo). Twenty-one anaesthetic events of 17 free-ranging lions (5 males and 12 females, body weight 105-211 kg) were studied in Zimbabwe. Medetomidine at 0.027-0.055 mg/kg (total dose 4-11 mg) and zolazepam-tiletamine at 0.38-1.32 mg/kg (total dose 50-275 mg) were administered i.m. by dart injection. The doses were gradually decreased to improve recovery. Respiratory and heart rates, rectal temperature and relative haemoglobin oxygen saturation (SpO2) were recorded every 15 min. Arterial blood samples were collected from 5 lions for analysis of blood gases and acid-base status. For anaesthetic reversal, atipamezole was administered i.m. at 2.5 or 5 times the medetomidine dose. Induction was smooth and all lions were anaesthetised with good muscle relaxation within 3.4-9.5 min after darting. The predictable working time was a minimum of 1 h and no additional drug doses were needed. Respiratory and heart rates and SpO2 were stable throughout anaesthesia, whereas rectal temperature changed significantly over time. Atipamezole at 2.5 times the medetomidine dose was sufficient for reversal and recoveries were smooth and calm in all lions independent of the atipamezole dose. First sign of recovery was observed 3-27 min after reversal. The animals were up walking 8-26 min after reversal when zolazepam-tiletamine doses < 1 mg/kg were used. In practice, a total dose of 6 mg medetomidine and 80 mg zolazepam-tiletamine and reversal with 15 mg atipamezole can be used for either sex of an adult or subadult lion. The drugs and doses used in this study provided a reliable, safe and reversible anaesthesia protocol for free-ranging lions.

  4. Seroepizootiological survey for selected viral infections in captive Asiatic lions (Panthera leo persica) from western India.

    PubMed

    Ramanathan, Anand; Malik, Pradeep K; Prasad, Gaya

    2007-09-01

    Infectious diseases have been responsible for large-scale declines in many endangered animals. Disease outbreaks in small populations have probably led to the eventual extinction of such endangered animals in the wild. The endangered Asiatic lion (Panthera leo persica) population may also face such threats. This was evident from this study on captive Asiatic lions from western India, which were sampled from December 1998 to March 1999. Fifty-six Asiatic lions, including 17 hybrid lions (Afro-Asian crosses) from six captive centers in western India, were tested for antibodies against canine distemper virus (CDV), feline parvovirus (FPV), feline immunodeficiency virus (FIV), and feline leukemia viral (FeLV) antigen. Agar gel immunodiffusion test and dot immunobinding assay were employed for CDV and FPV antibody detection. Commercial enzyme-linked immunosorbent assay kits were used for FIV antibody and FeLV antigen detection. Forty-nine of 56 lions (87.5%) were positive for CDV. All 56 (100%) lions were positive for FPV antibodies. There were no detectable levels of FIV antibodies and FeLV antigens. It was observed that CDV and FPV, two viruses known to cause high mortality in captive carnivores, were widely prevalent in these captive Asiatic lions. It is suggested that these seropositive animals will have the potential to pose a risk of infection to other seronegative animals. Hence, it is imperative to carefully consider any movement, translocation, or reintroduction of these animals to new regions. It is also recommended that these animals be required to undergo standard quarantine and disease screening protocols. The lack of exposure to pathogens, such as FIV and FeLV, would also be a risk, and, hence, identification of reservoirs and screening of in-contact animals is highly recommended. Vaccinations must be considered, using killed or other suitable viral vaccines, which have been proved to be safe, effective, and efficacious in endangered felids.

  5. Comparative skull analysis suggests species-specific captivity-related malformation in lions (Panthera leo).

    PubMed

    Saragusty, Joseph; Shavit-Meyrav, Anat; Yamaguchi, Nobuyuki; Nadler, Rona; Bdolah-Abram, Tali; Gibeon, Laura; Hildebrandt, Thomas B; Shamir, Merav H

    2014-01-01

    Lion (Panthera leo) populations have dramatically decreased worldwide with a surviving population estimated at 32,000 across the African savannah. Lions have been kept in captivity for centuries and, although they reproduce well, high rates of stillbirths as well as morbidity and mortality of neonate and young lions are reported. Many of these cases are associated with bone malformations, including foramen magnum (FM) stenosis and thickened tentorium cerebelli. The precise causes of these malformations and whether they are unique to captive lions remain unclear. To test whether captivity is associated with FM stenosis, we evaluated 575 lion skulls of wild (N = 512) and captive (N = 63) origin. Tiger skulls (N = 276; 56 captive, 220 wild) were measured for comparison. While no differences were found between males and females or between subadults and adults in FM height (FMH), FMH of captive lions (17.36±3.20 mm) was significantly smaller and with greater variability when compared to that in wild lions (19.77±2.11 mm). There was no difference between wild (18.47±1.26 mm) and captive (18.56±1.64 mm) tigers in FMH. Birth origin (wild vs. captive) as a factor for FMH remained significant in lions even after controlling for age and sex. Whereas only 20/473 wild lions (4.2%) had FMH equal to or smaller than the 5th percentile of the wild population (16.60 mm), this was evident in 40.4% (23/57) of captive lion skulls. Similar comparison for tigers found no differences between the captive and wild populations. Lions with FMH equal to or smaller than the 5th percentile had wider skulls with smaller cranial volume. Cranial volume remained smaller in both male and female captive lions when controlled for skull size. These findings suggest species- and captivity-related predisposition for the pathology in lions.

  6. Efficient Wideband Spectrum Sensing with Maximal Spectral Efficiency for LEO Mobile Satellite Systems.

    PubMed

    Li, Feilong; Li, Zhiqiang; Li, Guangxia; Dong, Feihong; Zhang, Wei

    2017-01-21

    The usable satellite spectrum is becoming scarce due to static spectrum allocation policies. Cognitive radio approaches have already demonstrated their potential towards spectral efficiency for providing more spectrum access opportunities to secondary user (SU) with sufficient protection to licensed primary user (PU). Hence, recent scientific literature has been focused on the tradeoff between spectrum reuse and PU protection within narrowband spectrum sensing (SS) in terrestrial wireless sensing networks. However, those narrowband SS techniques investigated in the context of terrestrial CR may not be applicable for detecting wideband satellite signals. In this paper, we mainly investigate the problem of joint designing sensing time and hard fusion scheme to maximize SU spectral efficiency in the scenario of low earth orbit (LEO) mobile satellite services based on wideband spectrum sensing. Compressed detection model is established to prove that there indeed exists one optimal sensing time achieving maximal spectral efficiency. Moreover, we propose novel wideband cooperative spectrum sensing (CSS) framework where each SU reporting duration can be utilized for its following SU sensing. The sensing performance benefits from the novel CSS framework because the equivalent sensing time is extended by making full use of reporting slot. Furthermore, in respect of time-varying channel, the spatiotemporal CSS (ST-CSS) is presented to attain space and time diversity gain simultaneously under hard decision fusion rule. Computer simulations show that the optimal sensing settings algorithm of joint optimization of sensing time, hard fusion rule and scheduling strategy achieves significant improvement in spectral efficiency. Additionally, the novel ST-CSS scheme performs much higher spectral efficiency than that of general CSS framework.

  7. Efficient Wideband Spectrum Sensing with Maximal Spectral Efficiency for LEO Mobile Satellite Systems

    PubMed Central

    Li, Feilong; Li, Zhiqiang; Li, Guangxia; Dong, Feihong; Zhang, Wei

    2017-01-01

    The usable satellite spectrum is becoming scarce due to static spectrum allocation policies. Cognitive radio approaches have already demonstrated their potential towards spectral efficiency for providing more spectrum access opportunities to secondary user (SU) with sufficient protection to licensed primary user (PU). Hence, recent scientific literature has been focused on the tradeoff between spectrum reuse and PU protection within narrowband spectrum sensing (SS) in terrestrial wireless sensing networks. However, those narrowband SS techniques investigated in the context of terrestrial CR may not be applicable for detecting wideband satellite signals. In this paper, we mainly investigate the problem of joint designing sensing time and hard fusion scheme to maximize SU spectral efficiency in the scenario of low earth orbit (LEO) mobile satellite services based on wideband spectrum sensing. Compressed detection model is established to prove that there indeed exists one optimal sensing time achieving maximal spectral efficiency. Moreover, we propose novel wideband cooperative spectrum sensing (CSS) framework where each SU reporting duration can be utilized for its following SU sensing. The sensing performance benefits from the novel CSS framework because the equivalent sensing time is extended by making full use of reporting slot. Furthermore, in respect of time-varying channel, the spatiotemporal CSS (ST-CSS) is presented to attain space and time diversity gain simultaneously under hard decision fusion rule. Computer simulations show that the optimal sensing settings algorithm of joint optimization of sensing time, hard fusion rule and scheduling strategy achieves significant improvement in spectral efficiency. Additionally, the novel ST-CSS scheme performs much higher spectral efficiency than that of general CSS framework. PMID:28117712

  8. Neurologic disease in captive lions (Panthera leo) with low-titer lion lentivirus infection.

    PubMed

    Brennan, Greg; Podell, Michael D; Wack, Raymund; Kraft, Susan; Troyer, Jennifer L; Bielefeldt-Ohmann, Helle; VandeWoude, Sue

    2006-12-01

    Lion lentivirus (LLV; also known as feline immunodeficiency virus of lion, Panthera leo [FIVPle]) is present in free-ranging and captive lion populations at a seroprevalence of up to 100%; however, clinical signs are rarely reported. LLV displays up to 25% interclade sequence diversity, suggesting that it has been in the lion population for some time and may be significantly host adapted. Three captive lions diagnosed with LLV infection displayed lymphocyte subset alterations and progressive behavioral, locomotor, and neuroanatomic abnormalities. No evidence of infection with other potential neuropathogens was found. Antemortem electrodiagnostics and radiologic imaging indicated a diagnosis consistent with lentiviral neuropathy. PCR was used to determine a partial lentiviral genomic sequence and to quantify the proviral burden in eight postmortem tissue specimens. Phylogenetic analysis demonstrated that the virus was consistent with the LLV detected in other captive and free-ranging lions. Despite progressive neurologic signs, the proviral load in tissues, including several regions of the brain, was low; furthermore, gross and histopathologic changes in the brain were minimal. These findings suggest that the symptoms in these animals resulted from nonspecific encephalopathy, similar to human immunodeficiency virus, FIV, and simian immunodeficiency virus (SIV) neuropathies, rather than a direct effect of active viral replication. The association of neuropathy and lymphocyte subset alterations with chronic LLV infection suggests that long-term LLV infection can have detrimental effects for the host, including death. This is similar to reports of aged sootey mangabeys dying from diseases typically associated with end-stage SIV infection and indicates areas for further research of lentiviral infections of seemingly adapted natural hosts, including mechanisms of host control and viral adaptation.

  9. Needle biopsy for hepatic vitamin A levels in lions (Panthera leo).

    PubMed

    Shamir, Merav H; Rubin, Gal; Aizenberg, Zachi; Berkovich, Zipi; Reifen, Ram; Horowitz, Igal; Bdolah-Abram, Tali; Aroch, Itamar

    2012-06-01

    Hypovitaminosis A (HA)-related skull malformations resulting in neurologic abnormalities and death have been, and still are, reported in captive lions (Panthera leo) worldwide. Liver vitamin A (VA) concentration is the most reliable indicator of animals' VA status, and its assessment is essential in prevention and treatment of HA in lions. A percutaneous needle liver biopsy using high-performance liquid chromatography ultraviolet retinoid analysis for VA concentration measurement was validated. It was first assessed in vitro using chicken liver. Later, the safety and feasibility of ultrasound-guided percutaneous needle liver biopsy was assessed in living lions. Hepatic VA concentrations in lion liver were measured using the above laboratory method. Mean chicken hepatic VA concentration in needle biopsy (NB) and wedge biopsy (WB) of the same liver lobes were 108.66 and 60.89 microg/g wet tissue, respectively, and were significantly (P = 0.03) correlated (r = 0.74). The calculated linear regression for predicting VA concentration in WB using NB VA for chicken liver was 25.194 + 0.3234x NB (microg/g). Four ultrasound-guided percutaneous needle liver biopsies were obtained from each of the four lions under general anesthesia. Mean hepatic VA concentration was 8.25 microg/g wet tissue (range 1.43-25.29 microg/g). Mean serum VA concentration, measured in these four lions was 1,011.1 nmol/L with a standard deviation of 337.91 nmol/L (range 590.26-1,077.2 nmol/L). The lions recovered uneventfully, and no complications were observed during a 4-yr follow-up period. In conclusion, the percutaneous needle liver biopsy technique is a reliable, practical, safe tool for obtaining liver tissue samples antemortem for assessment of the VA status in lions and can be used in future studies.

  10. Application of the NASCAP Spacecraft Simulation Tool to Investigate Electrodynamic Tether Current Collection in LEO

    NASA Technical Reports Server (NTRS)

    Adams, Mitzi; HabashKrause, Linda

    2012-01-01

    Recent interest in using electrodynamic tethers (EDTs) for orbital maneuvering in Low Earth Orbit (LEO) has prompted the development of the Marshall ElectroDynamic Tether Orbit Propagator (MEDTOP) model. The model is comprised of several modules which address various aspects of EDT propulsion, including calculation of state vectors using a standard orbit propagator (e.g., J2), an atmospheric drag model, realistic ionospheric and magnetic field models, space weather effects, and tether librations. The natural electromotive force (EMF) attained during a radially-aligned conductive tether results in electrons flowing down the tether and accumulating on the lower-altitude spacecraft. The energy that drives this EMF is sourced from the orbital energy of the system; thus, EDTs are often proposed as de-orbiting systems. However, when the current is reversed using satellite charged particle sources, then propulsion is possible. One of the most difficult challenges of the modeling effort is to ascertain the equivalent circuit between the spacecraft and the ionospheric plasma. The present study investigates the use of the NASA Charging Analyzer Program (NASCAP) to calculate currents to and from the tethered satellites and the ionospheric plasma. NASCAP is a sophisticated set of computational tools to model the surface charging of three-dimensional (3D) spacecraft surfaces in a time-varying space environment. The model's surface is tessellated into a collection of facets, and NASCAP calculates currents and potentials for each one. Additionally, NASCAP provides for the construction of one or more nested grids to calculate space potential and time-varying electric fields. This provides for the capability to track individual particles orbits, to model charged particle wakes, and to incorporate external charged particle sources. With this study, we have developed a model of calculating currents incident onto an electrodynamic tethered satellite system, and first results are shown

  11. Prevalence of Bartonella infection in wild African lions (Panthera leo) and cheetahs (Acinonyx jubatus).

    PubMed

    Molia, S; Chomel, B B; Kasten, R W; Leutenegger, C M; Steele, B R; Marker, L; Martenson, J S; Keet, D F; Bengis, R G; Peterson, R P; Munson, L; O'Brien, S J

    2004-05-20

    Bartonella species are emerging pathogens that have been isolated worldwide from humans and other mammals. Our objective was to estimate the prevalence of Bartonella infection in free-ranging African lions (Panthera leo) and cheetahs (Acinonyx jubatus). Blood and/or serum samples were collected from a convenience sample of 113 lions and 74 cheetahs captured in Africa between 1982 and 2002. Whole blood samples available from 58 of the lions and 17 of the cheetahs were cultured for evidence of Bartonella spp., and whole blood from 54 of the 58 lions and 73 of the 74 cheetahs tested for the presence of Bartonella DNA by TaqMan PCR. Serum samples from the 113 lions and 74 cheetahs were tested for the presence of antibodies against Bartonella henselae using an immunofluorescence assay. Three (5.2%) of the 58 lions and one (5.9%) of the 17 cheetahs were bacteremic. Two lions were infected with B. henselae, based on PCR/RFLP of the citrate synthase gene. The third lion and the cheetah were infected with previously unidentified Bartonella strains. Twenty-three percent of the 73 cheetahs and 3.7% of the 54 lions tested by TaqMan PCR were positive for Bartonella spp. B. henselae antibody prevalence was 17% (19/113) for the lions and 31% (23/74) for the cheetahs. The prevalence of seropositivity, bacteremia, and positive TaqMan PCR was not significantly different between sexes and age categories (juvenile versus adult) for both lions and cheetahs. Domestic cats are thus no longer the only known carriers of Bartonella spp. in Africa. Translocation of B. henselae seronegative and TaqMan PCR negative wild felids might be effective in limiting the spread of Bartonella infection.

  12. Active vehicle charging measurements in sounding rocket and space shuttle orbiter environments at Low Earth Orbit (LEO) altitude

    NASA Technical Reports Server (NTRS)

    Raitt, W. J.; Eccles, J. V.; Myers, N. B.; Thompson, D. C.; Banks, P. M.; Williamson, P. R.; Bush, R. I.; Hawkins, J.; Sasaki, S.; Oyama, K.-I.

    1987-01-01

    It was concluded that for electron beam emission up to 100mA, vehicle charging is not a significant problem with the Space Shuttle Orbiter. Similarly, sounding rocket payloads have no serious charging problems up to this level of beam current, provided that the maximum amount of the rocket skin is available to collect ionospheric electrons from the LEO altitude range. However, sounding rockets are marginal in their collecting area capability and other effects may occur to balance the beam current when operated at lower altitudes during the night.

  13. EcAMSat and BioSentinel: Autonomous Bio Nanosatellites Addressing Strategic Knowledge Gaps for Manned Spaceflight Beyond LEO

    NASA Technical Reports Server (NTRS)

    Padgen, Michael R.

    2017-01-01

    Manned missions beyond low Earth orbit (LEO) require that several strategic knowledge gaps about the effects of space travel on the human body be addressed. NASA Ames Research Center has been the leader in developing autonomous bio nanosatellites, including past successful missions for GeneSat, PharmaSat, and O/OREOS, that tackled some of these issues. These nanosatellites provide in situ measurements, which deliver insight into the dynamic changes in cell behavior in microgravity. In this talk, two upcoming bio nanosatellites developed at Ames, the E. coli Antimicrobial Satellite (EcAMSat) and BioSentinel, will be discussed. Both satellites contain microfluidic systems that precisely deliver nutrients to the microorganisms stored within wells of fluidic cards. Each well, in turn, has its own 3-color LED and detector system which is used to monitor changes in metabolic activity with alamarBlue, a redox indicator, and the optical density of the cells. EcAMSat investigates the effects of microgravity on bacterial resistance to antimicrobial drugs, vital knowledge for understanding how to maintain the health of astronauts in long-term and beyond LEO spaceflight. The behavior of wild type and mutant uropathic E. coli will be compared in microgravity and with ground data to help understand the molecular mechanisms behind antibiotic resistance and how these phenotypes might change in space. BioSentinel seeks to directly measure the effects of space radiation on budding yeast S. cerevisiae, particularly double strand breaks (DSB). While hitching a ride on the SLS EM-1 mission (Orion's first unmanned mission to the moon) in 2018, BioSentinel will be kicked off and enter into a heliocentric orbit, becoming the first study of the effects of radiation on living organisms outside LEO since the Apollo program. The yeast are stored in eighteen independent 16-well microfluidic cards, which will be individually activated over the 12 month mission duration. In addition to the wild

  14. An electrically conductive thermal control surface for spacecraft encountering Low-Earth Orbit (LEO) atomic oxygen indium tin oxide-coated thermal blankets

    NASA Technical Reports Server (NTRS)

    Bauer, J. L.

    1987-01-01

    An organic black thermal blanket material was coated with indium tin oxide (ITO) to prevent blanket degradation in the low Earth orbit (LEO) atomic oxygen environment. The blankets were designed for the Galileo spacecraft. Galileo was initially intended for space shuttle launch and would, therefore, have been exposed to atomic oxygen in LEO for between 10 and 25 hours. Two processes for depositing ITO are described. Thermooptical, electrical, and chemical properties of the ITO film are presented as a function of the deposition process. Results of exposure of the ITO film to atomic oxygen (from a shuttle flight) and radiation exposure (simulated Jovian environment) are also presented. It is shown that the ITO-protected thermal blankets would resist the anticipated LEO oxygen and Jovian radiation yet provide adequate thermooptical and electrical resistance. Reference is made to the ESA Ulysses spacecraft, which also used ITO protection on thermal control surfaces.

  15. Sedimentation survey of Lago Loíza, Trujillo Alto, Puerto Rico, July 2009

    USGS Publications Warehouse

    Soler-López, Luis R.; Licha-Soler, N.A.

    2014-01-01

    Lago Loíza is a reservoir formed at the confluence of Río Gurabo and Río Grande de Loíza in the municipality of Trujillo Alto in central Puerto Rico, about 10 kilometers (km) north of the town of Caguas, about 9 km northwest of Gurabo, and about 3 km south of Trujillo Alto (fig. 1). The Carraizo Dam is owned and operated by the Puerto Rico Aqueduct and Sewer Authority (PRASA), and was constructed in 1953 as a water-supply reservoir for the San Juan Metropolitan area. The dam is a concrete gravity structure that is located in a shallow valley and has a gently sloping left abutment and steep right abutment. Non-overflow sections flank the spillway section. Waterways include an intake structure for the pumping station and power plant, sluiceways, a trash sluice, and a spillway. The reservoir was built to provide a storage capacity of 26.8 million cubic meters (Mm3) of water at the maximum pool elevation of 41.14 meters (m) above mean sea level (msl) for the Sergio Cuevas Filtration Plant that serves the San Juan metropolitan area. The reservoir has a drainage area of 538 square kilometers (km2) and receives an annual mean rainfall that ranges from 1,600 to 5,000 millimeters per year (mm/yr). The principal streams that drain into Lago Loíza are the Río Grande de Loíza, Río Gurabo, and Río Cañas. Two other rivers, the Río Bairoa and Río Cagüitas, discharge into the Río Grande de Loíza just before it enters the reservoir. The combined mean annual runoff of the Río Grande de Loíza and the Río Gurabo for the 1960–2009 period of record is 323 Mm3. Flow from these streams constitutes about 89 percent of the total mean annual inflow of 364 Mm3 to the reservoir (U.S. Geological Survey, 2009). Detailed information about Lago Loíza reservoir structures, historical sediment accumulation, and a dredge conducted in 1999 are available in Soler-López and Gómez-Gómez (2005). During July 8–15, 2009, the U.S. Geological Survey (USGS) Caribbean Water Science

  16. 100-LBF LO2/LCH4 - Reaction Control Engine Technology Development for Future Space Vehicles

    NASA Technical Reports Server (NTRS)

    Robinson, Philip J.; Veith, Eric M.; Hurlbert, Eric A.; Jimenez, Rafael; Smith, Timothy D.

    2008-01-01

    The National Aeronautics and Space Administration (NASA) has identified liquid oxygen (LO2)/liquid methane (LCH4) propulsion systems as promising options for some future space vehicles. NASA issued a contract to Aerojet to develop a 100-lbf (445 N) LO2/LCH4 Reaction Control Engine (RCE) aimed at reducing the risk of utilizing a cryogenic reaction control system (RCS) on a space vehicle. Aerojet utilized innovative design solutions to develop an RCE that can ignite reliably over a broad range of inlet temperatures, perform short minimum impulse bits (MIB) at small electrical pulse widths (EPW), and produce excellent specific impulse (Isp) across a range of engine mixture ratios (MR). These design innovations also provide a start transient with a benign MR, ensuring good thrust chamber compatibility and long life. In addition, this RCE can successfully operate at MRs associated with main engines, enabling the RCE to provide emergency backup propulsion to minimize vehicle propellant load and overall system mass.

  17. Neutron matter from chiral two- and three-nucleon calculations up to N3LO

    NASA Astrophysics Data System (ADS)

    Drischler, C.; Carbone, A.; Hebeler, K.; Schwenk, A.

    2016-11-01

    Neutron matter is an ideal laboratory for nuclear interactions derived from chiral effective field theory since all contributions are predicted up to next-to-next-to-next-to-leading order (N3LO ) in the chiral expansion. By making use of recent advances in the partial-wave decomposition of three-nucleon (3 N ) forces, we include for the first time N3LO 3 N interactions in many-body perturbation theory (MBPT) up to third order and in self-consistent Green's function theory (SCGF). Using these two complementary many-body frameworks we provide improved predictions for the equation of state of neutron matter at zero temperature and also analyze systematically the many-body convergence for different chiral EFT interactions. Furthermore, we present an extension of the normal-ordering framework to finite temperatures. These developments open the way to improved calculations of neutron-rich matter including estimates of theoretical uncertainties for astrophysical applications.

  18. Co-expression of COX-2 and 5-LO in primary glioblastoma is associated with poor prognosis.

    PubMed

    Wang, Xingfu; Chen, Yupeng; Zhang, Sheng; Zhang, Lifeng; Liu, Xueyong; Zhang, Li; Li, Xiaoling; Chen, Dayang

    2015-11-01

    Cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LO) are important factors in tumorigenesis and malignant progression; however, studies of their roles in glioblastoma have produced conflicting results. To define the frequencies of COX-2 and 5-LO expression and their correlation with clinicopathological features and prognosis, tumor tissues from 76 cases of newly diagnosed primary ordinary glioblastoma were examined for COX-2 and 5-LO expression by immunohistochemistry. The expression levels of COX-2 and 5-LO and the relationships between the co-expression of COX-2/5-LO and patient age and gender, edema index (EI), Karnofsky Performance Scale and overall survival (OS) were analyzed. COX-2 and 5-LO were expressed in 73.7 % (56/76) and 92.1 % (70/76) of the samples, respectively. Among the clinicopathological characteristics, only age (>60 years) exhibited a significant association with the high expression of COX-2. No statistically significant correlations were found in the 5-LO cohort. A significant positive correlation was revealed between the COX-2 and 5-LO scores (r = 0.374; p = 0.001). The elevated co-expression of COX-2 and 5-LO was observed primarily in the patients over the age of 60 years. Patients with a high expression of COX-2 had a significantly shorter OS (p < 0.01), whereas the immunoexpression of 5-LO was not associated with the OS of patients with glioblastoma. Survival analysis indicated that simultaneous high levels of COX-2 and 5-LO expression were significantly correlated with poor OS and, conversely, that a low/low expression pattern of these two proteins was significantly associated with better OS (p < 0.05). Moreover, the Cox multivariable proportional hazard model showed that a high expression of COX-2, high co-expression of COX-2 and 5-LO, and a high Ki-67 index were significant predictors of shorter OS in primary glioblastoma, independent of age, gender, EI, 5-LO expression and p53 status. The hazard ratios for OS were 2.347 (95 % CI 1

  19. Combination of Vandetanib, Radiotherapy, and Irinotecan in the LoVo Human Colorectal Cancer Xenograft Model

    SciTech Connect

    Wachsberger, Phyllis; Burd, Randy; Ryan, Anderson; Daskalakis, Constantine; Dicker, Adam P.

    2009-11-01

    Purpose: The tumor growth kinetics of the human LoVo colorectal xenograft model was assessed in response to vandetanib, an orally available receptor tyrosine kinase inhibitor, radiotherapy (RT), or irinotecan (CPT-11), as single therapies and in combination. Methods and Materials: LoVo cells were injected subcutaneously into the right hind limb (5x10{sup 6} cells in 100muL phosphate-buffered saline) of athymic NCR NUM mice and tumors were grown to a volume of 200-300 mm{sup 3} before treatment. Vandetanib was administered at 50 mg/kg daily orally for 14 days starting on Day 1. RT was given as three fractions (3x3 Gy) on Days 1, 2, and 3. CPT-11 was given at 15 mg/kg intraperitoneally on Days 1 and 3. Tumor volumes were measured on a daily basis and calculated by measuring tumor diameters with digital calipers in two orthogonal dimensions. Results: All three single treatments (vandetanib, CPT-11, and radiation) significantly slowed LoVo colorectal tumor growth. Vandetanib significantly increased the antitumor effects of CPT-11 and radiation when given in combination with either of these treatments. These treatment combinations resulted in a slow tumor growth rate during the 2 weeks of vandetanib administration. The triple combination of vandetanib, CPT-11, and radiation produced the most marked improvement in response as observed by measurable shrinkage of tumors during the first week of treatment. Conclusions: The tumor growth delay kinetics observed in this study of the LoVo colorectal model suggest concurrent and sustained post-sequencing of vandetanib with cytotoxic therapy may be beneficial in tumors of this type.

  20. LoFASM: A Low Frequency All Sky Monitor for Radio Transients and Student Training

    DTIC Science & Technology

    2015-09-02

    Emission (STARGATE) project, a public-private partnership between UTB’s Center for Advanced Radio Astronomy and SpaceX , focused on RF technology...Corporation ( SpaceX ) to build a commercial orbital launch facility in South Texas. As a result of interactions between SpaceX engineers and LoFASM students...and faculty, SpaceX and CARA have joined forces to create the Spacecraft Tracking and Astronomical Research into Gigahertz Astrophysical

  1. Infra red active modes due to coupling of cyclotron excitation and LO phonons in polar semiconductor

    NASA Astrophysics Data System (ADS)

    Agrawal, Ratna; Dubey, Swati; Ghosh, S.

    2013-06-01

    Effects of free carrier concentration, external magnetic field and Callen effective charge on infra red active modes in a polar semiconductor have been analytically investigated using simple harmonic oscillator model. Callen effective charge considerably enhances reflectivity and shifts minima towards lower values of energy. Presence of magnetic field leads towards the coupling of collective cyclotron excitations with LO phonon giving rise to maximum reflectivity whereas cyclotron resonance absorption results into minimum reflectivity.

  2. A local framework for calculating coupled cluster singles and doubles excitation energies (LoFEx-CCSD)

    DOE PAGES

    Baudin, Pablo; Bykov, Dmytro; Liakh, Dmitry I.; ...

    2017-02-22

    Here, the recently developed Local Framework for calculating Excitation energies (LoFEx) is extended to the coupled cluster singles and doubles (CCSD) model. In the new scheme, a standard CCSD excitation energy calculation is carried out within a reduced excitation orbital space (XOS), which is composed of localised molecular orbitals and natural transition orbitals determined from time-dependent Hartree–Fock theory. The presented algorithm uses a series of reduced second-order approximate coupled cluster singles and doubles (CC2) calculations to optimise the XOS in a black-box manner. This ensures that the requested CCSD excitation energies have been determined to a predefined accuracy compared tomore » a conventional CCSD calculation. We present numerical LoFEx-CCSD results for a set of medium-sized organic molecules, which illustrate the black-box nature of the approach and the computational savings obtained for transitions that are local compared to the size of the molecule. In fact, for such local transitions, the LoFEx-CCSD scheme can be applied to molecular systems where a conventional CCSD implementation is intractable.« less

  3. The First Photometric Study of the Short-period Shallow Contact System LO Comae

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Han, Q. W.; Liu, J. Z.

    2016-12-01

    In this paper, the first complete photometric light curves in the B, V, and R passbands for an eclipsing binary LO Com are presented, and the photometric solution for the LO Com is derived by analyzing these light curves by using the Wilson and Devinney code. From the photometric solution, it is found that the LO Com is a W-type W UMa binary with a mass ratio of q={m}2/{m}1=2.478 and a contact degree of f=(3.2+/- 0.25) % . By combining the two new minimum times with those published earlier in the literature, we have found that the (O - C) curve shows a downward parabolic variation corresponding to a long-term decrease in the orbital period with a rate of {{d}}P/{{d}}t=-1.18× {10}-7 days yr-1. This long-term decrease in its orbital period may be caused by mass transfer from the more massive component to the less massive one.

  4. Nature of the X(5568) — A critical Laplace sum rule analysis at N2LO

    NASA Astrophysics Data System (ADS)

    Albuquerque, R.; Narison, S.; Rabemananjara, A.; Rabetiarivony, D.

    2016-06-01

    We scrutinize recent QCD spectral sum rules (QSSR) results to lowest order (LO) predicting the masses of the BK molecule and (su)(bd¯) four-quark states. We improve these results by adding NLO and N2LO corrections to the PT contributions giving a more precise meaning on the b-quark mass definition used in the analysis. We extract our optimal predictions using Laplace sum rule (LSR) within the standard stability criteria versus the changes of the external free parameters (τ-sum rule variable, tc continuum threshold and subtraction constant μ). The smallness of the higher order PT corrections justifies (a posteriori) the LO order results ⊕ the uses of the ambiguous heavy quark mass to that order. However, our predicted spectra in the range (5173 ˜ 5226) MeV, summarized in Table 7, for exotic hadrons built with four different flavors (buds), do not support some previous interpretations of the D0 candidate,1 X(5568), as a pure molecule or a four-quark state. If experimentally confirmed, it could result from their mixing with an angle: sin 2𝜃 ≈ 0.15. One can also scan the region (2327 ˜ 2444) MeV (where the Ds0∗(2317) might be a good candidate) and the one (5173 ˜ 5226) MeV for detecting these (cuds) and (buds) unmixed exotic hadrons (if any) via, eventually, their radiative or π+hadrons decays.

  5. Fast Calcium Imaging with Optical Sectioning via HiLo Microscopy.

    PubMed

    Lauterbach, Marcel A; Ronzitti, Emiliano; Sternberg, Jenna R; Wyart, Claire; Emiliani, Valentina

    2015-01-01

    Imaging intracellular calcium concentration via reporters that change their fluorescence properties upon binding of calcium, referred to as calcium imaging, has revolutionized our way to probe neuronal activity non-invasively. To reach neurons densely located deep in the tissue, optical sectioning at high rate of acquisition is necessary but difficult to achieve in a cost effective manner. Here we implement an accessible solution relying on HiLo microscopy to provide robust optical sectioning with a high frame rate in vivo. We show that large calcium signals can be recorded from dense neuronal populations at high acquisition rates. We quantify the optical sectioning capabilities and demonstrate the benefits of HiLo microscopy compared to wide-field microscopy for calcium imaging and 3D reconstruction. We apply HiLo microscopy to functional calcium imaging at 100 frames per second deep in biological tissues. This approach enables us to discriminate neuronal activity of motor neurons from different depths in the spinal cord of zebrafish embryos. We observe distinct time courses of calcium signals in somata and axons. We show that our method enables to remove large fluctuations of the background fluorescence. All together our setup can be implemented to provide efficient optical sectioning in vivo at low cost on a wide range of existing microscopes.

  6. A Network Access Control Framework for 6LoWPAN Networks

    PubMed Central

    Oliveira, Luís M. L.; Rodrigues, Joel J. P. C.; de Sousa, Amaro F.; Lloret, Jaime

    2013-01-01

    Low power over wireless personal area networks (LoWPAN), in particular wireless sensor networks, represent an emerging technology with high potential to be employed in critical situations like security surveillance, battlefields, smart-grids, and in e-health applications. The support of security services in LoWPAN is considered a challenge. First, this type of networks is usually deployed in unattended environments, making them vulnerable to security attacks. Second, the constraints inherent to LoWPAN, such as scarce resources and limited battery capacity, impose a careful planning on how and where the security services should be deployed. Besides protecting the network from some well-known threats, it is important that security mechanisms be able to withstand attacks that have not been identified before. One way of reaching this goal is to control, at the network access level, which nodes can be attached to the network and to enforce their security compliance. This paper presents a network access security framework that can be used to control the nodes that have access to the network, based on administrative approval, and to enforce security compliance to the authorized nodes. PMID:23334610

  7. A network access control framework for 6LoWPAN networks.

    PubMed

    Oliveira, Luís M L; Rodrigues, Joel J P C; de Sousa, Amaro F; Lloret, Jaime

    2013-01-18

    Low power over wireless personal area networks (LoWPAN), in particular wireless sensor networks, represent an emerging technology with high potential to be employed in critical situations like security surveillance, battlefields, smart-grids, and in e-health applications. The support of security services in LoWPAN is considered a challenge. First, this type of networks is usually deployed in unattended environments, making them vulnerable to security attacks. Second, the constraints inherent to LoWPAN, such as scarce resources and limited battery capacity, impose a careful planning on how and where the security services should be deployed. Besides protecting the network from some well-known threats, it is important that security mechanisms be able to withstand attacks that have not been identified before. One way of reaching this goal is to control, at the network access level, which nodes can be attached to the network and to enforce their security compliance. This paper presents a network access security framework that can be used to control the nodes that have access to the network, based on administrative approval, and to enforce security compliance to the authorized nodes.

  8. On LEO Debris Orbit Prediction Performance Using Tracking Data from a Single Station

    NASA Astrophysics Data System (ADS)

    Sang, J.

    2014-09-01

    Debris laser ranging during terminator time periods has become routine practice for some tracking stations. Processing tracking data from Mt Stromlo has shown that an orbit prediction accuracy of 20 arc seconds in the along-track direction for the next 24 hours was achievable for low Earth orbiting (LEO) debris using 2 passes of debris laser ranging data from a single station, separated by about 24 hours. The radial prediction error was in the order of tens of meter, for the Mt Stromlo and Shanghai tracking stations, respectively. The accuracies were determined by comparing the predicted orbits with subsequent tracking data from the same station. This accuracy assessment might be over-optimistic for other parts of orbits far away from the station because the generated orbit is only constrained by the data above the tracking station. Therefore, a verification is needed to confirm the achievability of the debris orbit prediction accuracy using the accurate debris laser data from a single station. In this paper, the verification results using satellite laser ranging (SLR) data from a single tracking station are presented. Starlette and Larets are chosen for this study and they have perigee altitudes of 815km and 690km, respectively. The SLR data is downloaded from the website of International Laser Ranging Service (ILRS) Network. The similar data scenario is assumed. That is, SLR data of only two passes separated by about 24 hours is used to determine the orbits and then the orbits are propagated forward for 7 days. The SLR data is corrupted with random errors of 1m standard deviation to reflect realistic debris laser ranging accuracy. The predicted orbits are then compared with the accurate Consolidated Prediction Format (CPF) orbits generated by the ILRS data centers. The study confirms that accuracy of 20 arc seconds in the along-track direction for 1-2 day orbit predictions, and tens of meter in the radial direction, are achievable. For the lower Larets satellite

  9. Consistent Ocean Mass Time Series from LEO Potential Field Missions (CONTIM)

    NASA Astrophysics Data System (ADS)

    Lück, Christina; Ren, Le; Androsov, Alexey; Kusche, Jürgen; Schröter, Jens; Danilov, Sergey; Rietbroek, Roelof

    2016-04-01

    Ocean mass variability on timescales of months to decades is still insufficiently understood. On these timescales, large-scale ocean bottom pressure (OBP) anomalies are associated both with wind induced variability as well as baroclinic processes, i.e. related to vertical shear of ocean density. The GRACE mission has been instrumental in quantifying such mass fluctuations, yet its lifetime is limited. The broader importance of non-tidal ocean mass variability for oceanography but also geodesy (i.e. for understanding the time-varying geoid, shape of the Earth's crust, centre of figure, Earth rotation) is obvious. Deep ocean processes can only be understood properly when not only sea surface height and upper ocean steric expansion are measured but deep ocean pressure anomalies are accounted for in addition. Apart from GRACE, the SWARM constellation may provide information on the lowest degrees of the time-variable gravity field of the Earth and therefore of large-scale oceanic processes. Here we introduce the project CONTIM, which is run in the framework of the German Special Priority Programme "Dynamic Earth" (SPP1788). In CONTIM we propose to combine expertise on precise satellite orbit determination, gravity field and mass modelling, and physical oceanography to retrieve, analyse and verify consistent time series of ocean mass variations from a set of low-flying Earth orbiters including GRACE, but extending the GRACE time series. This information is used to advance our understanding of oceanic movement, ocean warming and sea level rise. CONTIM will thus synergistically address three areas: (1) the methodology of precisely determining LEO orbits, applied here to the SWARM constellation. (2) a new method of retrieving large-scale time-varying gravity (TVG) and mass change associated with oceanic (and cryospheric and hydrological) processes from results of (1), based on forward modelling. (3) physical modelling of ocean mass variations, both for improved forward

  10. Novel low cost standardized Nano-Satellite structure bus for LEO missions

    NASA Astrophysics Data System (ADS)

    Anubhav, T.; Sarwesh, P.; Narayan, V.; Varma, P. A.; Prasad, R. A.; Loganathan, M.; Rao, D. N.; Sriram, S.; Venkatesh, M.

    This paper focuses on SRMSAT STRUCTURE BUS which is a standardized Nano-Satellite structure bus. It provides a standard platform for a wide variety of missions in LEO and can be realized in a very short developmental period. The bus was designed and developed for SRMSAT, the SRM University (Sri Ramaswamy Memorial University) student Nano-Satellite, by the undergraduate students and faculty of SRM University in collaboration with Indian Space Research Organization (ISRO). The bus can support payloads up to a mass of 20kg. SRMSAT STRUCTURE BUS has a mass of around 6 kg and dimensions 280mm × 280mm × 280mm with an available volume of 11000 cc. Vibration Testing of the bus has been performed upto 6.7 gRMS. This makes the satellite capable of being launched by any launch vehicle in the world. An innovative PCB mounting design has been introduced in this structure bus which facilitates mounting of a maximum 7 PCB trays independently, each tray capable of holding a 250 mm2 PCB. Structural analysis of SRMSAT STRUCTURE BUS was done using NX Nastran. The boundary conditions for each analysis were defined based on the loading conditions as specified by the launcher, PSLV (Polar Satellite Launch Vehicle). Optimization of each individual component was performed by maintaining a minimum threshold between the local frequencies of the component and global frequencies of the entire satellite. Static, Modal, Harmonic and Random Vibration analysis of the structure bus was performed. This paper also describes the methodology followed in the static and dynamic analysis of the structure bus to finalize the design. The results have been tested and validated at ISRO Satellite Centre, Bangalore with around 90% accuracy and the structure has been certified as a standard structure bus for Nano-satellite missions. In terms of expandability, this structure bus is capable of accommodating deployable solar panels. Also, the payload mounting is not only restricted to th- bottom deck but can

  11. Synergic use of satellite and ground based remote sensing methods for monitoring the San Leo rock cliff (Northern Italy)

    NASA Astrophysics Data System (ADS)

    Frodella, William; Ciampalini, Andrea; Gigli, Giovanni; Lombardi, Luca; Raspini, Federico; Nocentini, Massimiliano; Scardigli, Cosimo; Casagli, Nicola

    2016-07-01

    The historic town of San Leo (Emilia Romagna Region, northern Italy) is located on top of an isolated rock massif above the Marecchia River valley hillside. On February 27th 2014, a northeastern sector of the massif collapsed; minor structural damages were reported in the town and a few buildings were evacuated as a precautionary measure. Although no fatalities occurred and the San Leo cultural heritage suffered no damage, minor rock fall events kept taking place on the newly formed rock wall, worsening this hazardous situation. In this framework, a monitoring system based on remote sensing techniques, such as radar interferometry (both spaceborne and ground-based) and terrestrial laser scanning, was planned in order to monitor the ground deformation of the investigated area and to evaluate the residual risk. In this paper the main outlines of a 1-year monitoring activity are described, including a pre-event analysis of possible landslide precursors and a post-event analysis of the displacements of both the collapse-affected rock wall sector and the rock fall deposits.

  12. Pushing the Limits, Episode 2: K2 Observations of Extragalactic RR Lyrae Stars in the Dwarf Galaxy Leo IV

    NASA Astrophysics Data System (ADS)

    Molnár, L.; Pál, A.; Plachy, E.; Ripepi, V.; Moretti, M. I.; Szabó, R.; Kiss, L. L.

    2015-10-01

    We present the first observations of extragalactic pulsating stars in the K2 ecliptic survey of the Kepler space telescope. The variability of all three RR Lyrae stars in the dwarf spheroidal galaxy Leo IV was successfully detected, at a brightness of Kp ≈ 21.5 mag, from data collected during Campaign 1. We identified one modulated star and another likely Blazhko candidate with periods of 29.8 ± 0.9 days and more than 80 days, respectively. EPIC 210282473 represents the first star beyond the Magellanic Clouds for which the Blazhko period and cycle-to-cycle variations in the modulation were unambiguously measured. The photometric [Fe/H] indices of the stars agree with earlier results that Leo IV is a very metal-poor galaxy. Two out of the three stars blend with brighter background galaxies in the K2 frames. We demonstrate that image subtraction can be reliably used to extract photometry from faint confused sources, which will be crucial not only for the K2 mission but also for future space photometric missions.

  13. Verification of the GSICS GEO-LEO inter-calibration products with GEO-GEO collocation data

    NASA Astrophysics Data System (ADS)

    Yu, Fangfang; Wu, Xiangqian; Qian, Haifeng; Sindic-Rancic, Gordana

    2011-10-01

    The Global Space-based Inter-Calibration System (GSICS) geostationary (GEO) vs. low earth orbit (LEO) inter-calibration correction products have been routinely generated for years at NOAA to improve and harmonize the data quality of the operational GOES satellite for a better global weather monitoring, prediction and climate change studies. In this study, the collocated GOES-13 and GOES-15 Imager infrared (IR) data are used to validate the GSICS GEO-LEO Imager inter-calibration correction products. To compensate the impact of difference in the spectral response function (SRF) on the GSICS corrected GEO radiance, two radiative transfer models (RTM) with different atmospheric profiles are used to simulate the relations between the two GEO radiance values. The results of GEO-GEO inter-calibration shows that the mean Tb difference between GOES-13 and GOES-15 is less than 0.2K(Ch2), 0.65K(Ch3), 0.08K(Ch4) and 0.35K(Ch6). The two RTM models with different atmospheric profiles have significantly different impacts on the Tb difference at the two absorptive channels, Ch3 and Ch6, indicating that the impact of different optical path is not well addressed in this study. Future study should apply the double difference using the RTM as transfer to compensate for the SRF and viewing/optical path difference at each collocated pixel.

  14. LEO-to-ground polarization measurements aiming for space QKD using Small Optical TrAnsponder (SOTA).

    PubMed

    Carrasco-Casado, Alberto; Kunimori, Hiroo; Takenaka, Hideki; Kubo-Oka, Toshihiro; Akioka, Maki; Fuse, Tetsuharu; Koyama, Yoshisada; Kolev, Dimitar; Munemasa, Yasushi; Toyoshima, Morio

    2016-05-30

    Quantum communication, and more specifically Quantum Key Distribution (QKD), enables the transmission of information in a theoretically secure way, guaranteed by the laws of quantum physics. Although fiber-based QKD has been readily available since several years ago, a global quantum communication network will require the development of space links, which remains to be demonstrated. NICT launched a LEO satellite in 2014 carrying a lasercom terminal (SOTA), designed for in-orbit technological demonstrations. In this paper, we present the results of the campaign to measure the polarization characteristics of the SOTA laser sources after propagating from LEO to ground. The most-widely used property for encoding information in free-space QKD is the polarization, and especially the linear polarization. Therefore, studying its behavior in a realistic link is a fundamental step for proving the feasibility of space quantum communications. The results of the polarization preservation of two highly-polarized lasers are presented here, including the first-time measurement of a linearly-polarized source at λ = 976 nm and a circularly-polarized source at λ = 1549 nm from space using a realistic QKD-like receiver, installed in the Optical Ground Station at the NICT Headquarters, in Tokyo, Japan.

  15. A Comparative Far UV Spectroscopic Study of the Dwarf Novae VW Vul and X Leo During Quiescence

    NASA Astrophysics Data System (ADS)

    Henry, C. K.; Sion, E. M.

    2000-12-01

    VW Vulpecula and X Leo are two U Geminorum type dwarf novae, the latter with a newly found orbital period (0.16870+/-0.00007 days). The inclination angle of VW Vul is known to be 44+/-12 deg, the mass of the white dwarf is 0.24+/-0.06 Msun, a secondary mass of 0.14+/-0.01 Msun and the system appears to have an outburst period of 14-24 days (Ritter & Kolb 2000). X Leo has nearly the same orbital period, outburst recurrence time and outburst amplitude but more uncertain orbital parameters. We have carried out an IUE archival comparative study of the two systems. We have applied the Massa-Fitzpatrick (2000) flux calibration correction to the archival IUE NEWSIPS SWP spectra of these two systems, obtained during dwarf nova quiescence. We have carried out high gravity model atmosphere using the codes TLUSTY195, SYNSPEC42, ROTIN and accretion disk synthetic spectra from the grid of Wade and Hubeny (1998). We have determined the physical properties of the white dwarf accreters, including temperature, gravity, chemical abundances estimates, and the accretion rate during quiescence. We discuss our results in the context of the overall picture of accretion physics in dwarf novae and the effects of accretion on the white dwarf. This research was supported in part by NSF grant AST 99-01955, NASA ADP grant NAG5-8388 and by summer research funding from the NASA- Delaware Space Grant Colleges Consortium.

  16. Determining the Rotation Periods of an Inactive LEO Satellite and the First Korean Space Debris on GEO, KOREASAT 1

    NASA Astrophysics Data System (ADS)

    Choi, Jin; Jo, Jung Hyun; Kim, Myung-Jin; Roh, Dong-Goo; Park, Sun-Youp; Lee, Hee-Jae; Park, Maru; Choi, Young-Jun; Yim, Hong-Suh; Bae, Young-Ho; Park, Young-Sik; Cho, Sungki; Moon, Hong-Kyu; Choi, Eun-Jung; Jang, Hyun-Jung; Park, Jang-Hyun

    2016-06-01

    Inactive space objects are usually rotating and tumbling as a result of internal or external forces. KOREASAT 1 has been inactive since 2005, and its drift trajectory has been monitored with the optical wide-field patrol network (OWL-Net). However, a quantitative analysis of KOREASAT 1 in regard to the attitude evolution has never been performed. Here, two optical tracking systems were used to acquire raw measurements to analyze the rotation period of two inactive satellites. During the optical campaign in 2013, KOREASAT 1 was observed by a 0.6 m class optical telescope operated by the Korea Astronomy and Space Science Institute (KASI). The rotation period of KOREASAT 1 was analyzed with the light curves from the photometry results. The rotation periods of the low Earth orbit (LEO) satellite ASTRO-H after break-up were detected by OWL-Net on April 7, 2016. We analyzed the magnitude variation of each satellite by differential photometry and made comparisons with the star catalog. The illumination effect caused by the phase angle between the Sun and the target satellite was corrected with the system tool kit (STK) and two line element (TLE) technique. Finally, we determined the rotation period of two inactive satellites on LEO and geostationary Earth orbit (GEO) with light curves from the photometry. The main rotation periods were determined to be 5.2 sec for ASTRO-H and 74 sec for KOREASAT 1.

  17. LEO cooperative multi-spacecraft refueling mission optimization considering J2 perturbation and target's surplus propellant constraint

    NASA Astrophysics Data System (ADS)

    Zhao, Zhao; Zhang, Jin; Li, Hai-yang; Zhou, Jian-yong

    2017-01-01

    The optimization of an LEO cooperative multi-spacecraft refueling mission considering the J2 perturbation and target's surplus propellant constraint is studied in the paper. First, a mission scenario is introduced. One service spacecraft and several target spacecraft run on an LEO near-circular orbit, the service spacecraft rendezvouses with some service positions one by one, and target spacecraft transfer to corresponding service positions respectively. Each target spacecraft returns to its original position after obtaining required propellant and the service spacecraft returns to its original position after refueling all target spacecraft. Next, an optimization model of this mission is built. The service sequence, orbital transfer time, and service position are used as deign variables, whereas the propellant cost is used as the design objective. The J2 perturbation, time constraint and the target spacecraft's surplus propellant capability constraint are taken into account. Then, a hybrid two-level optimization approach is presented to solve the formulated mixed integer nonlinear programming (MINLP) problem. A hybrid-encoding genetic algorithm is adopted to seek the near optimal solution in the up-level optimization, while a linear relative dynamic equation considering the J2 perturbation is used to obtain the impulses of orbital transfer in the low-level optimization. Finally, the effectiveness of the proposed model and method is validated by numerical examples.

  18. Pursuing atmospheric water vapor retrieval through NDSA measurements between two LEO satellites: evaluation of estimation errors in spectral sensitivity measurements

    NASA Astrophysics Data System (ADS)

    Facheris, L.; Cuccoli, F.; Argenti, F.

    2008-10-01

    NDSA (Normalized Differential Spectral Absorption) is a novel differential measurement method to estimate the total content of water vapor (IWV, Integrated Water Vapor) along a tropospheric propagation path between two Low Earth Orbit (LEO) satellites. A transmitter onboard the first LEO satellite and a receiver onboard the second one are required. The NDSA approach is based on the simultaneous estimate of the total attenuations at two relatively close frequencies in the Ku/K bands and of a "spectral sensitivity parameter" that can be directly converted into IWV. The spectral sensitivity has the potential to emphasize the water vapor contribution, to cancel out all spectrally flat unwanted contributions and to limit the impairments due to tropospheric scintillation. Based on a previous Monte Carlo simulation approach, through which we analyzed the measurement accuracy of the spectral sensitivity parameter at three different and complementary frequencies, in this work we examine such accuracy for a particularly critical atmospheric status as simulated through the pressure, temperature and water vapor profiles measured by a high resolution radiosonde. We confirm the validity of an approximate expression of the accuracy and discuss the problems that may arise when tropospheric water vapor concentration is lower than expected.

  19. Revealing the maternal demographic history of Panthera leo using ancient DNA and a spatially explicit genealogical analysis

    PubMed Central

    2014-01-01

    Background Understanding the demographic history of a population is critical to conservation and to our broader understanding of evolutionary processes. For many tropical large mammals, however, this aim is confounded by the absence of fossil material and by the misleading signal obtained from genetic data of recently fragmented and isolated populations. This is particularly true for the lion which as a consequence of millennia of human persecution, has large gaps in its natural distribution and several recently extinct populations. Results We sequenced mitochondrial DNA from museum-preserved individuals, including the extinct Barbary lion (Panthera leo leo) and Iranian lion (P. l. persica), as well as lions from West and Central Africa. We added these to a broader sample of lion sequences, resulting in a data set spanning the historical range of lions. Our Bayesian phylogeographical analyses provide evidence for highly supported, reciprocally monophyletic lion clades. Using a molecular clock, we estimated that recent lion lineages began to diverge in the Late Pleistocene. Expanding equatorial rainforest probably separated lions in South and East Africa from other populations. West African lions then expanded into Central Africa during periods of rainforest contraction. Lastly, we found evidence of two separate incursions into Asia from North Africa, first into India and later into the Middle East. Conclusions We have identified deep, well-supported splits within the mitochondrial phylogeny of African lions, arguing for recognition of some regional populations as worthy of independent conservation. More morphological and nuclear DNA data are now needed to test these subdivisions. PMID:24690312

  20. R&D of a Next Generation LEO System for Global Multimedia Mobile Satellite Communications

    NASA Astrophysics Data System (ADS)

    Morikawa, E.; Motoyoshi, S.; Koyama, Y.; Suzuki, R.; Yasuda, Y.

    2002-01-01

    Next-generation LEO System Research Center (NeLS) was formed in the end of 1997 as a research group under the Telecommunications Advancement Organization of Japan, in cooperation with the telecommunications operators, manufacturers, universities and governmental research organization. The aim of this project is to develop new technology for global multimedia mobile satellite communications services with a user data rate around 2Mbps for handy terminals. component of the IMT-2000, and the second generation of the big-LEO systems. In prosecuting this project, two-phase approach, phase 1 and phase 2, is considered. Phase 1 is the system definition and development of key technologies. In Phase 2, we plan to verify the developed technology in Phase 1 on space. From this year we shifted the stage to Phase 2, and are now developing the prototype of on-board communication systems for flight tests, which will be planed at around 2006. The satellite altitude is assumed to be 1200 km in order to reduce the number of satellites, to avoid the Van Allen radiation belts and to increase the minimum elevation angle. Ten of the circular orbits with 55 degree of inclination are selected to cover the earth surface from -70 to 70 degree in latitude. 12 satellites are positioned at regular intervals in each orbit. In this case, the minimum elevation angle from the user terminal can be keep more than 20 degree for the visibility of the satellite, and 15 degree for simultaneous visibility of two satellites. Then, NeLS Research Center was focusing on the development of key technologies as the phase 1 project. Four kinds of key technologies; DBF satellite antenna, optical inter-satellite link system, satellite network technology with on-board ATM switch and variable rate modulation were selected. Satellite Antenna Technology: Development of on-board direct radiating active phased array antenna with digital beam forming technology would be one of the most important breakthroughs for the

  1. Y4lO of Rhizobium sp. strain NGR234 is a symbiotic determinant required for symbiosome differentiation.

    PubMed

    Yang, Feng-Juan; Cheng, Li-Li; Zhang, Ling; Dai, Wei-Jun; Liu, Zhe; Yao, Nan; Xie, Zhi-Ping; Staehelin, Christian

    2009-02-01

    Type 3 (T3) effector proteins, secreted by nitrogen-fixing rhizobia with a bacterial T3 secretion system, affect the nodulation of certain host legumes. The open reading frame y4lO of Rhizobium sp. strain NGR234 encodes a protein with sequence similarities to T3 effectors from pathogenic bacteria (the YopJ effector family). Transcription studies showed that the promoter activity of y4lO depended on the transcriptional activator TtsI. Recombinant Y4lO protein expressed in Escherichia coli did not acetylate two representative mitogen-activated protein kinase kinases (human MKK6 and MKK1 from Medicago truncatula), indicating that YopJ-like proteins differ with respect to their substrate specificities. The y4lO gene was mutated in NGR234 (strain NGROmegay4lO) and in NGR Omega nopL, a mutant that does not produce the T3 effector NopL (strain NGR Omega nopLOmegay4lO). When used as inoculants, the symbiotic properties of the mutants differed. Tephrosia vogelii, Phaseolus vulgaris cv. Yudou No. 1, and Vigna unguiculata cv. Sui Qing Dou Jiao formed pink effective nodules with NGR234 and NGR Omega nopL Omega y4lO. Nodules induced by NGR Omega y4lO were first pink but rapidly turned greenish (ineffective nodules), indicating premature senescence. An ultrastructural analysis of the nodules induced by NGR Omega y4lO revealed abnormal formation of enlarged infection droplets in ineffective nodules, whereas symbiosomes harboring a single bacteroid were frequently observed in effective nodules induced by NGR234 or NGR Omega nopL Omega y4lO. It is concluded that Y4lO is a symbiotic determinant involved in the differentiation of symbiosomes. Y4lO mitigated senescence-inducing effects caused by the T3 effector NopL, suggesting synergistic effects for Y4lO and NopL in nitrogen-fixing nodules.

  2. Revisión de tecnología y riesgos: refinerías de petróleo - Hoja informativa para las comunidades

    EPA Pesticide Factsheets

    La Agencia de Protección Ambiental (EPA, por sus siglas en inglés) emitió un reglamento final que mejorará significativamente la calidad del aire en los vecindarios cercanos a las refinerías de petróleo mediante un control más exhaustivo de las emisiones a

  3. German Lunar Exploration Orbiter (LEO): Providing a Globally Covered, Highly Resolved, Integrated, Geological, Geochemical, and Geophysical Data Base of the Moon

    NASA Astrophysics Data System (ADS)

    Jaumann, R.; Spohn, T.; Hiesinger, H.; Jessberger, E. K.; Neukum, G.; Oberst, J.; Helbert, J.; Christensen, U.; Keller, H. U.; Hartogh, P.; Glassmeier, K.-H.; Auster, H.-U.; Moreira, A.; Werner, M.; Pätzold, M.; Palme, H.; Wimmer-Schweingruber, R.; Mandea

    2008-03-01

    LEO is planned to be launched in 2012 and shall orbit the Moon for about four years at low altitude (<50 km) in order to map the Moon geomorphologically, geochemically, and geophysically with resolutions down to less than 1 m globally.

  4. The Modeling of Fuzzy Systems Based on Lee-Oscillatory Chaotic Fuzzy Model (LoCFM)

    NASA Astrophysics Data System (ADS)

    Wong, Max H. Y.; Liu, James N. K.; Shum, Dennis T. F.; Lee, Raymond S. T.

    This paper introduces a new fuzzy membership function — LEE-oscillatory Chaotic Fuzzy Model (LoCFM). The development of this model is based on fuzzy logic and the incorporation of chaos theory — LEE Oscillator. Prototype systems are being developed for handling imprecise problems, typically involving linguistic expression and fuzzy semantic meaning. In addition, the paper also examines the mechanism of the LEE Oscillator through analyzing its structure and neural dynamics. It demonstrates the potential application of the model in future development.

  5. G-LoSA: An efficient computational tool for local structure-centric biological studies and drug design.

    PubMed

    Lee, Hui Sun; Im, Wonpil

    2016-04-01

    Molecular recognition by protein mostly occurs in a local region on the protein surface. Thus, an efficient computational method for accurate characterization of protein local structural conservation is necessary to better understand biology and drug design. We present a novel local structure alignment tool, G-LoSA. G-LoSA aligns protein local structures in a sequence order independent way and provides a GA-score, a chemical feature-based and size-independent structure similarity score. Our benchmark validation shows the robust performance of G-LoSA to the local structures of diverse sizes and characteristics, demonstrating its universal applicability to local structure-centric comparative biology studies. In particular, G-LoSA is highly effective in detecting conserved local regions on the entire surface of a given protein. In addition, the applications of G-LoSA to identifying template ligands and predicting ligand and protein binding sites illustrate its strong potential for computer-aided drug design. We hope that G-LoSA can be a useful computational method for exploring interesting biological problems through large-scale comparison of protein local structures and facilitating drug discovery research and development. G-LoSA is freely available to academic users at http://im.compbio.ku.edu/GLoSA/.

  6. Semen cryopreservation and radical reduction capacity of seminal fluid in captive African lion (Panthera leo).

    PubMed

    Luther, I; Jakop, U; Lueders, I; Tordiffe, A; Franz, C; Schiller, J; Kotze, A; Müller, K

    2017-02-01

    Optimizing cryopreservation protocols for nondomestic felids contributes to the successful development of assisted reproduction techniques and genetic resource banking. In this study, we describe a simple cryopreservation procedure for African lion (Panthera leo) ejaculates, which was tested with different packaging options and different sperm numbers per dose. By applying urethral catheterization and electroejaculation, 17 ejaculates with greater than 20% motile and greater than 5% progressively motile sperm were collected. A lyophilized extender (a modified egg yolk-Tes-Tris-fructose-glycerol medium) was rehydrated and added in one step at ambient temperature (∼25 °C) to semen, which was prediluted in cell culture medium M199. After slow cooling of insulated samples to 15 °C in a refrigerator (4 °C), the samples were fast frozen over the surface of liquid nitrogen or in a dry shipper. Aliquots of 300 μL containing 20 × 10(6) sperm were frozen in cryovials and in 0.5-mL straws. Differences were observed in the total motility after thawing between vial (31.5 ± 14.1%) and straw freezing (20.1 ± 8.6%). However, the subpopulations of vital (22.7 ± 7.8% for vial and 19.8 ± 8.5% for straw) and progressively motile (10.0 ± 7.9% for vial and 10.0 ± 6.4% for straw) sperm after washing and 1 hour incubation at 38 °C were of similar magnitude, velocity, and linearity for both packaging options. After freezing of five ejaculates with 20, 60, and 100 × 10(6) sperm per dose, best results were achieved at the lowest concentration. In general, post-thaw results were highly variable (2.2% and 56.5% total motility) and not correlated to motility or morphology of the fresh semen. To further characterize semen quality, we assessed the protective potential of seminal fluid against oxidative stress, which might be challenged on freeze thawing. The capacity of seminal fluid to reduce radicals was measured in 10 semen samples by electron spin resonance

  7. The nearby interstellar medium toward α Leo. UV observations and modeling of a warm cloud within hot gas

    NASA Astrophysics Data System (ADS)

    Gry, Cecile; Jenkins, Edward B.

    2017-01-01

    Aims: Our aim is to characterize the conditions in the nearest interstellar cloud. Methods: We analyze interstellar absorption features in the full UV spectrum of the nearby (d = 24 pc) B8 IVn star α Leo (Regulus). Observations were obtained with STIS at high resolution and high signal-to-noise ratio by the HST ASTRAL Treasury program. We derive column densities for many key atomic species and interpret their partial ionizations. Results: The gas in front of α Leo exhibits two absorption components. The main one is kinematically identified as the local interstellar cloud (LIC) that surrounds the Sun. The second component is shifted by +5.6 km s-1 relative to the main component, in agreement with results for other lines of sight in this region of the sky, and shares its ionization and physical conditions. The excitation of the C II fine-structure levels and the ratio of Mg I to Mg II reveal a temperature T = 6500 (+750, -600) K and electron density n(e) = 0.11 (+0.025, -0.03) cm-3. Our investigation of the ionization balance yields the ion fractions for 10 different atoms and indicates that about 1/3 of the hydrogen atoms are ionized. Metals are significantly depleted onto grains, with sulfur showing [S/H] -0.27. N(H I) = 1.9 (+0.9, -0.6) × 1018 cm-3, which indicates that this partly neutral gas occupies only 2 to 8 parsecs (about 13%) of the space toward the star, with the remaining volume being filled with a hot gas that emits soft X-rays. We do not detect any absorption features from the highly ionized species that could be produced in an interface between the warm medium and the surrounding hot gas, possibly because of non-equilibrium conditions or a particular magnetic field orientation that reduces thermal conduction. Finally, the radial velocity of the LIC agrees with that of the Local Leo Cold Cloud, indicating that they may be physically related.

  8. Higgs boson gluon-fusion production beyond threshold in N3LO QCD

    SciTech Connect

    Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Furlan, Elisabetta; Gehrmann, Thomas; Herzog, Franz; Mistlberger, Bernhard

    2015-03-18

    In this study, we compute the gluon fusion Higgs boson cross-section at N3LO through the second term in the threshold expansion. This calculation constitutes a major milestone towards the full N3LO cross section. Our result has the best formal accuracy in the threshold expansion currently available, and includes contributions from collinear regions besides subleading corrections from soft and hard regions, as well as certain logarithmically enhanced contributions for general kinematics. We use our results to perform a critical appraisal of the validity of the threshold approximation at N3LO in perturbative QCD.

  9. Soft Expansion of Double-Real-Virtual Corrections to Higgs Production at N$^3$LO

    SciTech Connect

    Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Furlan, Elisabetta; Herzog, Franz; Mistlberger, Bernhard

    2015-05-15

    We present methods to compute higher orders in the threshold expansion for the one-loop production of a Higgs boson in association with two partons at hadron colliders. This process contributes to the N3LO Higgs production cross section beyond the soft-virtual approximation. We use reverse unitarity to expand the phase-space integrals in the small kinematic parameters and to reduce the coefficients of the expansion to a small set of master integrals. We describe two methods for the calculation of the master integrals. The first was introduced for the calculation of the soft triple-real radiation relevant to N3LO Higgs production. The second uses a particular factorization of the three body phase-space measure and the knowledge of the scaling properties of the integral itself. Our result is presented as a Laurent expansion in the dimensional regulator, although some of the master integrals are computed to all orders in this parameter.

  10. Time-of-Flight Detector System with Low Background Performance for the IBEX-lo Sensor

    NASA Astrophysics Data System (ADS)

    Moebius, E.; Kucharek, H.; Granoff, M.; King, B.; Longworth, S.; Saul, L.; Fuselier, S.; Hertzberg, E.; Livi, S.; Paschalidis, N.; Schlemm, C.; Scheer, J.; Wurz, P.; Wieser, M.

    2006-12-01

    Over the course of the IBEX Mission the IBEX-lo sensor will provide images of energetic neutral H atoms (ENA) from the termination shock in the energy range 10 2000 eV as well as the directional flow distribution of interstellar neutral O in spring and fall. The sensor combines a mechanical collimator to restrict the detectable arrival directions, an atom to negative ion conversion surface, an electrostatic analyzer, post-acceleration of up to 20 keV, and time-of-flight (TOF) mass analysis. In this combination the TOF system provides the necessary mass separation to distinguish different species and effective background suppression through coincidence detection techniques. Because the flux of the heliospheric ENAs is very low and generates rather low count rates a triple coincidence system is used with secondary electrons produced in two consecutive carbon foils, followed by the final detection of the ions in a micro-channelplate. These three signals are combined into three independent TOF measurements. A flight-like engineering test unit of the IBEX-lo TOF subsystem has been built and tested. Meanwhile the flight model of the sensor is in fabrication. It will be shown that the combination of several TOF measurements provides very effective means to suppress background and to identify minor species, whose fluxes are several orders of magnitude below the main species. Results from the testing of the engineering unit will be discussed in the light of the IBEX science objectives.

  11. LO Peg: surface differential rotation, flares, and spot-topographic evolution

    NASA Astrophysics Data System (ADS)

    Karmakar, Subhajeet; Pandey, J. C.; Savanov, I. S.; Taş, G.; Pandey, S. B.; Misra, K.; Joshi, S.; Dmitrienko, E. S.; Sakamoto, T.; Gehrels, N.; Okajima, T.

    2016-07-01

    Using the wealth of ˜24 yr multiband data, we present an in-depth study of the star-spot cycles, surface differential rotations (SDR), optical flares, evolution of star-spot distributions, and coronal activities on the surface of young, single, main-sequence, ultrafast rotator LO Peg. From the long-term V-band photometry, we derive rotational period of LO Peg to be 0.4231 ± 0.0001 d. Using the seasonal variations on the rotational period, the SDR pattern is investigated, and shows a solar-like pattern of SDR. A cyclic pattern with period of ˜2.7 yr appears to be present in rotational period variation. During the observations, 20 optical flares are detected with a flare frequency of ˜1 flare per two days and with flare energy of ˜1031-34 erg. The surface coverage of cool spots is found to be in the range of ˜9-26 per cent. It appears that the high- and low-latitude spots are interchanging their positions. Quasi-simultaneous observations in X-ray, UV, and optical photometric bands show a signature of an excess of X-ray and UV activities in spotted regions.

  12. Soft Expansion of Double-Real-Virtual Corrections to Higgs Production at N$^3$LO

    DOE PAGES

    Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; ...

    2015-05-15

    We present methods to compute higher orders in the threshold expansion for the one-loop production of a Higgs boson in association with two partons at hadron colliders. This process contributes to the N3LO Higgs production cross section beyond the soft-virtual approximation. We use reverse unitarity to expand the phase-space integrals in the small kinematic parameters and to reduce the coefficients of the expansion to a small set of master integrals. We describe two methods for the calculation of the master integrals. The first was introduced for the calculation of the soft triple-real radiation relevant to N3LO Higgs production. The secondmore » uses a particular factorization of the three body phase-space measure and the knowledge of the scaling properties of the integral itself. Our result is presented as a Laurent expansion in the dimensional regulator, although some of the master integrals are computed to all orders in this parameter.« less

  13. Mapping the Space Radiation Environment in LEO Orbit by the SATRAM Timepix Payload On Board the Proba-V Satellite

    NASA Astrophysics Data System (ADS)

    Granja, Carlos; Polansky, Stepan; Sospisil, Stanislav; Owens, Alan; Mellab, Karim

    2016-08-01

    The compact spacecraft payload SATRAM is operating in LEO orbit since 2013 on board the Proba-V satellite from ESA and provides high-resolution wide-range radiation monitoring of the satellite environment. Equipped with the pixel detector Timepix, the technology demonstration payload determines the composition (particle types) and spectral characterization (stopping power) of the mixed radiation field with quantum imaging sensitivity, charged particle tracking, energy loss and directionality capability. With a polar orbit (sun synchronous, 98° inclination) and altitude of 820 km the space radiation field is continuously sampled over the entire planet every few days. Results are given in the form of spatial- and time- correlated maps of dose rate and particle flux. Comparison is made between quiescent and geomagnetic storm activity periods.

  14. Estimated performance and future potential of solar dynamic and photovoltaic power systems for selected LEO and HEO missions

    NASA Technical Reports Server (NTRS)

    Bents, David J.; Lu, Cheng Y.

    1989-01-01

    Solar photovoltaic and thermal dynamic power systems for application to selected low-earth-orbit (LEO) and high-earth-orbit (HEO) missions are characterized in the regime 7 to 35 kWe. Input parameters to the characterization are varied to correspond to anticipated introduction of improved or new technologies. A comparative assessment is made of the two power system types for emerging technologies in cells and arrays, energy storage, optical surfaces, heat engines, thermal energy storage and thermal management. The assessment is made to common ground rules and assumptions. The four missions (Space Station, sun-synchronous, Van Allen belt, and GEO) are representative of the anticipated range of multikilowatt earth-orbit missions. The results give the expected performance, mass and drag of multikilowatt earth-orbiting solar power systems and show how the overall system figure of merit will improve as new component technologies are incorporated.

  15. VizieR Online Data Catalog: 10 Leo in YJ, H, K, L and M bands spectra (Nicholls+, 2017)

    NASA Astrophysics Data System (ADS)

    Nicholls, C. P.; Lebzelter, T.; Smette, A.; Wolff, B.; Hartman, H.; Kaufl, H.-U.; Przybilla, N.; Ramsay, S.; Uttenthaler, S.; Wahlgren, G. M.; Bagnulo, S.; Hussain, G. A. J.; Nieva, M.-F.; Seemann, U.; Seifahrt, A.

    2016-09-01

    The data presented is the fully reduced CRIRES-POP spectrum of the K giant 10 Leo. The spectrum covers the entire near-infrared as accessible to the ground, i.e. the Y, J, H, K, L, and M bands, and is split into five ascii files corresponding to the division of the photometric bandpasses by CRIRES: YJ, H, K, L, M. The spectrum is presented at R=90,000, at rest wavelengths in vacuum, having been corrected for telluric absorption, and normalised to the local pseudocontinuum. Some areas of residual telluric contamination have been masked, in the files the flux values of these areas have been replaced with '---'. (5 data files).

  16. Serologic and molecular characterization of tickborne pathogens in lions (Panthera leo) from the Fasano Safari Park, Italy.

    PubMed

    Torina, Alessandra; Naranjo, Victoria; Pennisi, Maria Grazia; Patania, Tatiana; Vitale, Fabrizio; Laricchiuta, Pietro; Alongi, Angelina; Scimeca, Salvatore; Kocan, Katherine M; de la Fuente, José

    2007-12-01

    Lions (Panthera leo) are an endangered species threatened by illegal hunting, habitat loss, and infectious diseases. Little is known about the tick-borne pathogens that infect lions and could contribute to population declines. The objective of this study was to characterize Rickettsia spp., Anaplasma phagocytophilum, and Coxiella burnetii infections in 10 lions from the Fasano Safari Park in Italy by serology, polymerase chain reaction, and sequence analysis. Although animals did not show clinical signs of tick-borne diseases, evidence of infection with C. burnetii, spotted fever group Rickettsia sp., and A. phagocytophilum were found in 50%, 20%, and 10% of the lions, respectively. One of the lions tested positive for all three pathogens. This study is the first report of molecular evidence of infection with C. burnetii, Rickettsia sp., and A. phagocytophilum in lions and provides evidence that these felids become infected and serve as hosts for tick-transmitted bacteria.

  17. A spaceborne, pulsed UV laser system for re-entering or nudging LEO debris, and re-orbiting GEO debris

    NASA Astrophysics Data System (ADS)

    Phipps, Claude R.; Bonnal, Christophe

    2016-01-01

    Among the problems raised by the presence of debris in Earth Orbit, the question of large derelict satellites in Geostationary Orbit (GEO) is of major importance. More than 1000 defunct GEO satellites cruise in the vicinity of this unique orbit and pose the question of orbital slot availability. It is proposed to use lasers in GEO to reorbit the large debris in the graveyard zone, some 300 km above GEO. The principle of orbital transfer by laser ablation is recalled, and two different methods are described. These lasers can also serve for small debris deorbiting and large debris nudging in Low Earth Orbit (LEO). Technical details are provided, as well as a preliminary mass budget.

  18. Further studies on Toxascaris leonina (Linstow, 1902) (Ascaridida: Ascarididae) from Felis lynx (Linnaeus) and Panthera leo (Linnaeus) (Carnivora: Felidae).

    PubMed

    Xue, Li-Mei; Chai, Jing-Bo; Guo, Yan-Ning; Zhang, Lu-Ping; Li, Liang

    2014-03-01

    Toxascaris leonina (Linstow, 1902) is a most common intestinal parasite of various animals in Felidae and Canidae. In the present paper, light and scanning electron microscopy (SEM) were used to study the morphological aspects of adult worms of this nematode in detail, based on the material collected from Panthera leo (Linnaeus) and Felis lynx (Linnaeus) (Carnivora: Felidae) in China. The results showed that there were some morphometric differences between the present material and the previous studies, including the body size, the width and length of cervical alae, the number of denticles on each lip and the tail length of the female. Previously unreported morphological features were also revealed. These supplementary morphological and morphometric data contributed to a more accurate identification of this worldwide distributed ascarid nematode.

  19. Planning constraints of low grazing altitude GEO-LEO laser links based on in-orbit data

    NASA Astrophysics Data System (ADS)

    Sterr, Uwe; Dallmann, Daniel; Heine, Frank; Tröndle, Daniel; Meyer, Rolf; Lutzer, Michael; Benzi, Edoardo

    2016-11-01

    Part of the operational concept for laser communication networks such as the European data relay system is planning constraints. In addition to hard constraints such as angular range of the actuators, there is also the atmosphere, which has a gradual increasing impact as the distance between laser beam path and earth decreases. The shortest distance between the laser beam path and the surface of the earth is called "grazing altitude." The atmosphere impacts spatial acquisition as well as communication performance. In-orbit measurement data of geostationary orbit-low-Earth orbit (GEO-LEO) links between two laser communication terminals (LCT) developed by TESAT-Spacecom, Germany, in the frame of Alphasat TDP1 optical GEO-relay demonstration program are presented. Planning constraint guidelines are formulated based on the observed influence. TESAT-Spacecom's LCTs use a highly sensitive and high-performance coherent transmission technology and a beaconless spatial acquisition system.

  20. A CubeSAT payload for in-situ monitoring of pentacene degradation due to atomic oxygen etching in LEO

    NASA Astrophysics Data System (ADS)

    Gorreta, Sergi; Pons-Nin, Joan; López, Gema; Figueras, Eduard; Jové-Casulleras, Roger; Araguz, Carles; Via, Pol; Camps, Adriano; Domínguez-Pumar, Manuel

    2016-09-01

    This paper reports and discusses the design and ground tests of a CubeSat payload which allows to measure, in-situ and in real time, the degradation of a polymer of electronic interest due to atomic oxygen etching in LEO. It provides real-time information on how the degradation occurs, eliminating the need to work with samples recovered once the mission has finished. The polymer, TIPS-Pentacene, is deposited on the surface of a microelectromechanical (MEMS) cantilever, which works as a resonator embedded in a Pulsed Digital Oscillator circuit. The mass losses in the polymer due to atomic oxygen corrosion produce variations in the resonant frequency of the MEMS, which is continuously sensed by the circuit and transmitted to the ground. This way, polymer mass losses around 10-12 kg can be detected during the mission. The payload is a part of the 3Cat-1 mission, a nano-satellite aimed at carrying out several scientific experiments.

  1. Characterization of the Catalog Fengyun-1C Fragments and Their Long-term Effect on the LEO Environment

    NASA Technical Reports Server (NTRS)

    Liou, J.-C.; Johnson, N. L.

    2008-01-01

    The intentional breakup of Fengyun-1C on 11 January 2007 created the most severe orbital debris cloud in history. More than 2500 large fragments were identified and tracked by the U.S. Space Surveillance Network by the end of the year. The altitude where the event occurred was probably the worst location for a major breakup in the low Earth orbit (LEO) region, since it was already highly populated with operational satellites and debris generated from previous breakups. The addition of so many fragments not only poses a realistic threat to operational satellites in the region, but also increases the instability (i.e., collision cascade effect) of the debris population there. Preliminary analysis of the large Fengyun-1C fragments indicates that their size and area-to-mass ratio (A/M) distributions are very different from those of other known events. About half of the fragments appear to be composed of light-weight materials and more than 100 of them have A/M values exceeding 1 square meter per kilogram, consistent with thermal blanket pieces. In addition, the orbital elements of the fragments suggest nontrivial velocity gain by the fragment cloud during the impact. These important characteristics were incorporated into a numerical simulation to assess the long-term impact of the Fengyun-1C fragments to the LEO debris environment. The main objectives of the simulation were to evaluate (1) the collision probabilities between the Fengyun-1C fragments and the rest of the catalog population and (2) the collision activities and population growth in the region in the next 100 years.

  2. The Method for Calculating Atmospheric Drag Coefficient Based on the Characteristics of Along-track Error in LEO Orbit Prediction

    NASA Astrophysics Data System (ADS)

    Wang, H. B.; Zhao, C. Y.; Liu, Z. G.; Zhang, W.

    2016-07-01

    The errors of atmosphere density model and drag coefficient are the major factors to restrain the accuracy of orbit prediction for the LEO (Low Earth Orbit) objects, which would affect unfavorably the space missions that need a high-precision orbit. This paper brings out a new method for calculating the drag coefficient based on the divergence laws of prediction error's along-track component. Firstly, we deduce the expression of along-track error in LEO's orbit prediction, revealing the comprehensive effect of the initial orbit and model's errors in the along-track direction. According to this expression, we work out a suitable drag coefficient adopted in prediction step on the basis of some certain information from orbit determination step, which will limit the increasing rate of along-track error and reduce the largest error in this direction, then achieving the goal of improving the accuracy of orbit prediction. In order to verify the method's accuracy and successful rate in the practice of orbit prediction, we use the full-arcs high precision position data from the GPS receiver on GRACE-A. The result shows that this new method can significantly improve the accuracy of prediction by about 45%, achieving a successful rate of about 71% and an effective rate of about 86%, with respect to classical method which uses the fitted drag coefficient directly from orbit determination step. Furthermore, the new method shows a preferable application value, because it is effective for low, moderate, and high solar radiation levels, as well as some quiet and moderate geomagnetic activity condition.

  3. The causal role of the occipital face area (OFA) and lateral occipital (LO) cortex in symmetry perception.

    PubMed

    Bona, Silvia; Cattaneo, Zaira; Silvanto, Juha

    2015-01-14

    Symmetry is an important cue in face and object perception. Here we used fMRI-guided transcranial magnetic stimulation (TMS) to shed light on the role of the occipital face area (OFA), a key region in face processing, and the lateral occipital (LO) cortex, a key area in object processing, in symmetry detection. In the first experiment, we applied TMS over the rightOFA, its left homolog (leftOFA), rightLO, and vertex (baseline) while participants were discriminating between symmetric and asymmetric dot patterns. Stimulation of rightOFA and rightLO impaired performance, causally implicating these two regions in detection of symmetry in low-level dot configurations. TMS over rightLO but not rightOFA also significantly impaired detection of nonsymmetric shapes defined by collinear Gabor patches, demonstrating that rightOFA responds to symmetry but not to all cues mediating figure-ground segregation. The second experiment showed a causal role for rightOFA but not rightLO in facial symmetry detection. Overall, our results demonstrate that both the rightOFA and rightLO are sensitive to symmetry in dot patterns, whereas only rightOFA is causally involved in facial symmetry detection.

  4. 'Introducing Michael Gove to Loïc Wacquant': Why Social Work Needs Critical Sociology.

    PubMed

    Michael Garrett, Paul

    2016-06-01

    In 2013, Michael Gove, then Secretary of State for Education and Health in the UK coalition government, criticised social workers for laying insufficient emphasis on the 'agency' of individuals and for being too preoccupied with social and economic inequalities. Such a perspective, which is not unique to Gove, needs to be countered by reaffirming the significance of an expansively critical sociology for social work. In this context, the thematic concerns of the French theorist, Loïc Wacquant, illuminates key aspects of social work engagement with clients which Gove and his ideological associates appear intent on ignoring. The issues raised have significant political resonances given the pending UK General Election taking place in May 2015.

  5. Screening materials with the XIA UltraLo alpha particle counter at Southern Methodist University

    SciTech Connect

    Nakib, M. Z.; Cooley, J.; Kara, B.; Qiu, H.; Scorza, S.; Guiseppe, V. E.; Rielage, K.; Schnee, R. W.

    2013-08-08

    Southern Methodist University houses one of five existing commercially available UltraLo 1800 production model alpha counters made by XIA LLC. The instrument has an electron drift chamber with a 707 cm{sup 2} or 1800 cm{sup 2} counting region which is determined by selecting the inner electrode size. The SMU team operating this device is part of the SuperCDMS screening working group, and uses the alpha counter to study the background rates from the decay of radon in materials used to construct the SuperCDMS experiment. We have studied four acrylic samples obtained from the MiniCLEAN direct dark matter search with the XIA instrument demonstrating its utility in low background experiments by investigating the plate-out of {sup 210}Pb and comparing the effectiveness of cleaning procedures in removing {sup 222}Rn progenies from the samples.

  6. The Eclipsing Central Stars of the Planetary Nebulae Lo 16 and PHR J1040-5417

    NASA Astrophysics Data System (ADS)

    Hillwig, Todd C.; Frew, David; Jones, David; Crispo, Danielle

    2017-01-01

    Binary central stars of planetary nebula are a valuable tool in understanding common envelope evolution. In these cases both the resulting close binary system and the expanding envelope (the planetary nebula) can be studied directly. In order to compare observed systems with common envelope evolution models we need to determine precise physical parameters of the binaries and the nebulae. Eclipsing central stars provide us with the best opportunity to determine high precision values for mass, radius, and temperature of the component stars in these close binaries. We present photometry and spectroscopy for two of these eclipsing systems; the central stars of Lo 16 and PHR 1040-5417. Using light curves and radial velocity curves along with binary modeling we provide physical parameters for the stars in both of these systems.

  7. The LEO Archipelago: A system of earth-rings for communications, mass-transport to space, solar power, and control of global warming

    NASA Astrophysics Data System (ADS)

    Meulenberg, Andrew; Karthik Balaji, P. S.

    2011-06-01

    Man's quest to get into space is hindered by major problems (e.g., system-development and capital costs, expense of putting mass into orbit, trapped-radiation belts, and environmental impact of a large increase in rocket launches). A multi-purpose low-earth-orbit system of rings circling the earth - the "LEO ARCHIPELAGO TM" - is proposed as a means of solving or bypassing many of them. A fiber-optic ring about the earth would be an initial testing and developmental stage for the Ring Systems, while providing cash-flow through a LEO-based, high-band-width, world-wide communication system. A low-earth-orbit-based space-elevator system, "Sling-on-a-Ring TM", is proposed as the crucial developmental stage of the LEO Archipelago. Being a LEO-based heavy-mass lifter, rather than earth- or GEO-based, it is much less massive and therefore less costly than other proposed space-elevators. With the advent of lower-cost, higher-mass transport to orbit, the options for further space development (e.g., space solar power, radiation, and space-debris dampers, sun shades, and permanent LEO habitation) are greatly expanded. This paper provides an update of the Sling-on-a-Ring concept in terms of new materials, potential applications, and trade-offs associated with an earlier model. The impact of Colossal Carbon Tubes, CCT, a new material with high tensile strength, extremely-low density, and other favorable properties, and other new technologies (e.g., solar-powered lasers, power beaming to near-space and earth, and thermal-control systems) on the development of associated LEO-Ring systems is also explored. The material's effect on the timeline for the system development indicates the feasibility of near-term implementation of the system (possibly within the decade). The Sling-on-a-Ring can provide a less-expensive, environment-friendly mode of access to space. This would pave the way (via eventual operation at >1000 t per day by 2050) for large scale development of space

  8. Diagnosing the Neutral Interstellar Gas Flow at 1 AU with IBEX-Lo

    NASA Astrophysics Data System (ADS)

    Möbius, E.; Kucharek, H.; Clark, G.; O'Neill, M.; Petersen, L.; Bzowski, M.; Saul, L.; Wurz, P.; Fuselier, S. A.; Izmodenov, V. V.; McComas, D. J.; Müller, H. R.; Alexashov, D. B.

    2009-08-01

    Every year in fall and spring the Interstellar Boundary Explorer (IBEX) will observe directly the interstellar gas flow at 1 AU over periods of several months. The IBEX-Lo sensor employs a powerful triple time-of-flight mass spectrometer. It can distinguish and image the O and He flow distributions in the northern fall and spring, making use of sensor viewing perpendicular to the Sun-pointing spin axis. To effectively image the narrow flow distributions IBEX-Lo has a high angular resolution quadrant in its collimator. This quadrant is employed selectively for the interstellar gas flow viewing in the spring by electrostatically shutting off the remainder of the aperture. The operational scenarios, the expected data, and the necessary modeling to extract the interstellar parameters and the conditions in the heliospheric boundary are described. The combination of two key interstellar species will facilitate a direct comparison of the pristine interstellar flow, represented by He, which has not been altered in the heliospheric boundary region, with a flow that is processed in the outer heliosheath, represented by O. The O flow distribution consists of a depleted pristine component and decelerated and heated neutrals. Extracting the latter so-called secondary component of interstellar neutrals will provide quantitative constraints for several important parameters of the heliosheath interaction in current global heliospheric models. Finding the fraction and width of the secondary component yields an independent value for the global filtration factor of species, such as O and H. Thus far filtration can only be inferred, barring observations in the local interstellar cloud proper. The direction of the secondary component will provide independent information on the interstellar magnetic field strength and orientation, which has been inferred from SOHO SWAN Ly- α backscattering observations and the two Voyager crossings of the termination shock.

  9. Bayesian estimation of Karhunen-Loève expansions; A random subspace approach

    NASA Astrophysics Data System (ADS)

    Chowdhary, Kenny; Najm, Habib N.

    2016-08-01

    One of the most widely-used procedures for dimensionality reduction of high dimensional data is Principal Component Analysis (PCA). More broadly, low-dimensional stochastic representation of random fields with finite variance is provided via the well known Karhunen-Loève expansion (KLE). The KLE is analogous to a Fourier series expansion for a random process, where the goal is to find an orthogonal transformation for the data such that the projection of the data onto this orthogonal subspace is optimal in the L2 sense, i.e., which minimizes the mean square error. In practice, this orthogonal transformation is determined by performing an SVD (Singular Value Decomposition) on the sample covariance matrix or on the data matrix itself. Sampling error is typically ignored when quantifying the principal components, or, equivalently, basis functions of the KLE. Furthermore, it is exacerbated when the sample size is much smaller than the dimension of the random field. In this paper, we introduce a Bayesian KLE procedure, allowing one to obtain a probabilistic model on the principal components, which can account for inaccuracies due to limited sample size. The probabilistic model is built via Bayesian inference, from which the posterior becomes the matrix Bingham density over the space of orthonormal matrices. We use a modified Gibbs sampling procedure to sample on this space and then build probabilistic Karhunen-Loève expansions over random subspaces to obtain a set of low-dimensional surrogates of the stochastic process. We illustrate this probabilistic procedure with a finite dimensional stochastic process inspired by Brownian motion.

  10. Downregulation of MDM2 expression by RNAi inhibits LoVo human colorectal adenocarcinoma cells growth and the treatment of LoVo cells with mdm2siRNA3 enhances the sensitivity to cisplatin

    SciTech Connect

    Yu Yan . E-mail: gyfyuyan@hotmail.com; Sun Ping . E-mail: sunny19750502@hotmail.com; Sun Lichun; Liu Guoyi; Chen Guohua . E-mail: olivebranch_82@hotmail.com; Shang Lihua . E-mail: leval1000@sina.com; Wu Hongbo . E-mail: whpwl@sina.com; Hu Jing; Li Yue; Mao Yinling; Sui Guangjie; Sun Xiwen

    2006-01-06

    To investigate the biological effect of mdm2 in human colorectal adenocarcinoma LoVo cells, three mdm2siRNA constructions were recombinated and transient transfected into human colorectal adenocarcinoma LoVo cells with low differentiation character in vitro. The results showed that mdm2siRNA3 reduced mRNA level of mdm2 and protein level of mdm2, leading to proliferation inhibition on LoVo cells, and reduced tumor growth in nude mice. It was found that depletion of MDM2 in this pattern promoted apoptosis of LoVo cells and Cisplatin (DDP) treated in the mdm2siRNA3 transfected cell population would result in a substantial decrease by MTT colorimetry. Decreasing the MDM2 protein level in LoVo cells by RNAi could significantly inhibit tumor growth both in vitro and in vivo, which indicated that mdm2 gene played a definite role in the development and aggressiveness of human colon carcinoma. It also could be a therapeutic target in colorectal carcinoma. The synergistic activation of RNAi and cell toxicity agents indicated that the combination of chemotherapy and gene therapy will be a promising approach in the future.

  11. Radiation Environment at LEO in the frame of Space Monitoring Data Center at Moscow State University - recent, current and future missions

    NASA Astrophysics Data System (ADS)

    Myagkova, Irina; Kalegaev, Vladimir; Panasyuk, Mikhail; Svertilov, Sergey; Bogomolov, Vitaly; Bogomolov, Andrey; Barinova, Vera; Barinov, Oleg; Bobrovnikov, Sergey; Dolenko, Sergey; Mukhametdinova, Ludmila; Shiroky, Vladimir; Shugay, Julia

    2016-04-01

    Radiation Environment of Near-Earth space is one of the most important factors of space weather. Space Monitoring Data Center of Moscow State University provides operational control of radiation conditions at Low Earth's Orbits (LEO) of the near-Earth space using data of recent (Vernov, CORONAS series), current (Meteor-M, Electro-L series) and future (Lomonosov) space missions. Internet portal of Space Monitoring Data Center of Skobeltsyn Institute of Nuclear Physics of Lomonosov Moscow State University (SINP MSU) http://swx.sinp.msu.ru/ provides possibilities to control and analyze the space radiation conditions in the real time mode together with the geomagnetic and solar activity including hard X-ray and gamma- emission of solar flares. Operational data obtained from space missions at L1, GEO and LEO and from the Earth's magnetic stations are used to represent radiation and geomagnetic state of near-Earth environment. The models of space environment that use space measurements from different orbits were created. Interactive analysis and operational neural network forecast services are based on these models. These systems can automatically generate alerts on particle fluxes enhancements above the threshold values, both for SEP and relativistic electrons of outer Earth's radiation belt using data from GEO and LEO as input. As an example of LEO data we consider data from Vernov mission, which was launched into solar-synchronous orbit (altitude 640 - 83 0 km, inclination 98.4°, orbital period about 100 min) on July 8, 2014 and began to receive scientific information since July 20, 2014. Vernov mission have provided studies of the Earth's radiation belt relativistic electron precipitation and its possible connection with atmosphere transient luminous events, as well as the solar hard X-ray and gamma-emission measurements. Radiation and electromagnetic environment monitoring in the near-Earth Space, which is very important for space weather study, was also realised

  12. STELLAR POPULATIONS AND STRUCTURAL PROPERTIES OF ULTRA FAINT DWARF GALAXIES, CANES VENATICI I, BOOeTES I, CANES VENATICI II, AND LEO IV

    SciTech Connect

    Okamoto, Sakurako; Arimoto, Nobuo; Yamada, Yoshihiko; Onodera, Masato

    2012-01-10

    We take deep images of four ultra faint dwarf (UFD) galaxies, Canes Venatici I (CVn I), Booetes I (Booe I), Canes Venatici II (CVn II), and Leo IV, using the Suprime-Cam on the Subaru Telescope. Color-magnitude diagrams (CMDs) extend below main-sequence turnoffs (MSTOs) and yield measurements of the ages of stellar populations. The stellar populations of three faint galaxies, the Booe I, CVn II, and Leo IV dwarf spheroidal galaxies (dSphs), are estimated to be as old as the Galactic globular cluster M92. We confirm that Booe I dSph has no intrinsic color spread in the MSTO and no spatial difference in the CMD morphology, which indicates that Booe I dSph is composed of an old single stellar population. One of the brightest UFDs, CVn I dSph, shows a relatively younger age ({approx}12.6 Gyr) with respect to Booe I, CVn II, and Leo IV dSphs, and the distribution of red horizontal branch (HB) stars is more concentrated toward the center than that of blue HB stars, suggesting that the galaxy contains complex stellar populations. Booe I and CVn I dSphs show the elongated and distorted shapes. CVn II dSph has the smallest tidal radius of a Milky Way satellite and has a distorted shape, while Leo IV dSph shows a less concentrated spherical shape. The simple stellar population of faint UFDs indicates that the gases in their progenitors were removed more effectively than those of brighter dSphs at the occurrence of their initial star formation. This is reasonable if the progenitors of UFDs belong to less massive halos than those of brighter dSphs.

  13. Technology Development for Human Exploration Beyond LEO in the New Millennium IAA-13-3 Strategies and Plans for Human Mars Missions

    NASA Technical Reports Server (NTRS)

    Larson, William E.; Lueck, Dale E.; Parrish, Clyde F.; Sanders, Gerald B.; Trevathan, Joseph R.; Baird, R. Scott; Simon, Tom; Peters, T.; Delgado, H. (Technical Monitor)

    2001-01-01

    As we look forward into the new millennium, the extension of human presence beyond Low-Earth Orbit (LEO) looms large in the plans of NASA. The Agency's Strategic Plan specifically calls out the need to identify and develop technologies for 100 and 1000-day class missions beyond LEO. To meet the challenge of these extended duration missions, it is important that we learn how to utilize the indigenous resources available to us on extraterrestrial bodies. This concept, known as In-Situ Resource Utilization (ISRU) can greatly reduce the launch mass & cost of human missions while reducing the risk. These technologies may also pave the way for the commercial development of space. While no specific target beyond LEO is identified in NASA's Strategic Plan, mission architecture studies have been on-going for the Moon, Mars, Near-Earth Asteroids and Earth/Moon & Earth/Sun Libration Points. As a result of these studies, the NASA Office of Space Flight (Code M) through the Johnson and Kennedy Space Centers, is leading the effort to develop ISRU technologies and systems to meet the current and future needs of human missions beyond LEO and on to Mars. This effort also receives support from the NASA Office of Biological and Physical Research (Code U), the Office of Space Science (Code S), and the Office of Aerospace Technology (Code R). This paper will present unique developments in the area of fuel and oxidizer production, breathing air production, water production, C02 collection, separation of atmospheric gases, and gas liquefaction and storage. A technology overview will be provided for each topic along with the results achieved to date, future development plans, and the mission architectures that these technologies support.

  14. Summary of LO2/Ethanol OMS/RCS Technology and Advanced Development 99-2744

    NASA Technical Reports Server (NTRS)

    Curtis, Leslie A.; Hurlbert, Eric A.

    1999-01-01

    NASA is pursuing non-toxic propellant technologies applicable to RLV and Space Shuttle orbital maneuvering system (OMS) and reaction control system (RCS). The primary objectives of making advancements in an OMS/RCS system are improved safety, reliability, and reduced operations and maintenance cost, while meeting basic operational and performance requirements. An OMS/RCS has a high degree of direct interaction with the vehicle and crew and requires subsystem and components that are compatible with integration into the vehicle with regard to external mold-line, power, and thermal control. In July 1997, a Phase I effort for the technology and advanced development of an upgrade of the space shuttle was conducted to define the system architecture, propellant tank, feed system, RCS thrusters, and OMS engine. Phase I of the project ran from July 1997 to October 1998. Phase II is currently being planned for the development and test of full-scale prototype of the system in 1999 and 2000. The choice of pressure-fed liquid oxygen (LO2) and ethanol is the result of numerous trade studies conducted from 1980 to 1996. Liquid oxygen and ethanol are clean burning, high-density propellants that provide a high degree of commonality with other spacecraft subsystems including life support, power, and thermal control, and with future human exploration and development of space missions. The key to this pressure-fed system is the use of subcooled liquid oxygen at 350 psia. In this approach, there is 80 degrees R of subcooling, which means that boil-off will not occur until the temperature has risen 80 R. The sub-cooling results naturally from loading propellants at 163 R, which is the saturation temperature at 14.7 psia, and then pressurizing to 350 psia on the launch pad. Thermal insulation and conditioning techniques are then used to limit the LO2 temperature to 185 R maximum, and maintain the sub-cooling. The other key is the wide temperature range of ethanol, -173 F to +300 F, which

  15. Study of LO-phonon decay in semiconductors for hot carrier solar cell

    NASA Astrophysics Data System (ADS)

    Levard, Hugo; Vidal, Julien; Laribi, Sana; Guillemoles, Jean-François

    2014-03-01

    Knowledge of phonon decay is of crucial importance when studying basic properties of semiconductors, since they are closely related to Raman linewidth and non-equilibrium-hot-carriers cooling. The latter indeed cools down to the bottom of the conduction band within a picosecond range because of electron-phonon interaction. The eventual emitted hot phonons then decay in few picoseconds. The hot carriers cooling can be slowed down by considering the decay rate dependence of phonon on conservation rules, whose tuning may reduce the allowed two-phonon final states density. This is of direct interest for the third generation photovoltaic devices that are Hot Carrier Solar Cells (HCSC), in which the photoexcited carriers are extracted at an energy higher than thermal equilibrium. One of the HCSC main challenges then is to find an absorber material in which the hot phonons has a relaxation time longer than the carriers cooling time, so that we can expect the electron to ``reabsorb'' a phonon, slowing down the electronic cooling. HCSC yield is ultimately limited by LO phonon decay, though. In this work, we present theoretical results obtained from ab initio calculations of phonon lifetime in III-V and IV-IV semiconductors through a three-phonon process. Common approximations in the literature are questioned. In particular, we show that the usual ``zone-center approximation'' is not valid in some specific semiconductors. The analysis allows to correctly investigate phonon decay mechanisms in bulk and nanostructured materials.

  16. Infinite-Cutoff Renormalization of the Chiral Nucleon-Nucleon Interaction up to N3LO

    NASA Astrophysics Data System (ADS)

    Zeoli, Ch.; Machleidt, R.; Entem, D. R.

    2013-12-01

    Naively, the "best" method of renormalization is the one where a momentum cutoff is taken to infinity while maintaining stable results due to a cutoff-dependent adjustment of counterterms. We have applied this renormalization method in the non-perturbative calculation of phase-shifts for nucleon-nucleon ( NN) scattering using chiral NN potentials up to next-to-next-to-next-to-leading order (N3LO). For lower partial waves, we find that there is either no convergence with increasing order or, if convergence occurs, the results do not always converge to the empirical values. For higher partial waves, we always observe convergence to the empirical phase shifts (except for the 3G5 state). Furthermore, no matter what the order is, one can use only one or no counterterm per partial wave, creating a rather erratic scheme of power counting that does not allow for a systematic order-by-order improvement of the predictions. The conclusion is that infinite-cutoff renormalization is inappropriate for chiral NN interactions, which should not come as a surprise, since the chiral effective field theory (chiral EFT), these interactions are based upon, is designed for momenta below the chiral-symmetry breaking scale of about 1 GeV. Therefore, this value for the hard scale should also be perceived as the appropriate upper limit for the momentum cutoff.

  17. Aggregation of LoD 1 building models as an optimization problem

    NASA Astrophysics Data System (ADS)

    Guercke, R.; Götzelmann, T.; Brenner, C.; Sester, M.

    3D city models offered by digital map providers typically consist of several thousands or even millions of individual buildings. Those buildings are usually generated in an automated fashion from high resolution cadastral and remote sensing data and can be very detailed. However, not in every application such a high degree of detail is desirable. One way to remove complexity is to aggregate individual buildings, simplify the ground plan and assign an appropriate average building height. This task is computationally complex because it includes the combinatorial optimization problem of determining which subset of the original set of buildings should best be aggregated to meet the demands of an application. In this article, we introduce approaches to express different aspects of the aggregation of LoD 1 building models in the form of Mixed Integer Programming (MIP) problems. The advantage of this approach is that for linear (and some quadratic) MIP problems, sophisticated software exists to find exact solutions (global optima) with reasonable effort. We also propose two different heuristic approaches based on the region growing strategy and evaluate their potential for optimization by comparing their performance to a MIP-based approach.

  18. Image Steganography using Karhunen-Loève Transform and Least Bit Substitution

    NASA Astrophysics Data System (ADS)

    Chadha, Ankit; Satam, Neha; Sood, Rakshak; Bade, Dattatray

    2013-10-01

    As communication channels are increasing in number, reliability of faithful communication is reducing. Hacking and tempering of data are two major issues for which security should be provided by channel. This raises the importance of steganography. In this paper, a novel method to encode the message information inside a carrier image has been described. It uses Karhunen-Lo\\`eve Transform for compression of data and Least Bit Substitution for data encryption. Compression removes redundancy and thus also provides encoding to a level. It is taken further by means of Least Bit Substitution. The algorithm used for this purpose uses pixel matrix which serves as a best tool to work on. Three different sets of images were used with three different numbers of bits to be substituted by message information. The experimental results show that algorithm is time efficient and provides high data capacity. Further, it can decrypt the original data effectively. Parameters such as carrier error and message error were calculated for each set and were compared for performance analysis.

  19. Optimized suppression of coherent noise from seismic data using the Karhunen-Loève transform.

    PubMed

    Montagne, Raúl; Vasconcelos, Giovani L

    2006-07-01

    Signals obtained in land seismic surveys are usually contaminated with coherent noise, among which the ground roll (Rayleigh surface waves) is of major concern for it can severely degrade the quality of the information obtained from the seismic record. This paper presents an optimized filter based on the Karhunen-Loève transform for processing seismic images contaminated with ground roll. In this method, the contaminated region of the seismic record, to be processed by the filter, is selected in such way as to correspond to the maximum of a properly defined coherence index. The main advantages of the method are that the ground roll is suppressed with negligible distortion of the remnant reflection signals and that the filtering procedure can be automated. The image processing technique described in this study should also be relevant for other applications where coherent structures embedded in a complex spatiotemporal pattern need to be identified in a more refined way. In particular, it is argued that the method is appropriate for processing optical coherence tomography images whose quality is often degraded by coherent noise (speckle).

  20. Pseudo-scalar Higgs boson production at N^3LO_{ {A}}+N^3LL'

    NASA Astrophysics Data System (ADS)

    Ahmed, Taushif; Bonvini, Marco; Kumar, M. C.; Mathews, Prakash; Rana, Narayan; Ravindran, V.; Rottoli, Luca

    2016-12-01

    We consider the production of a pseudo-scalar particle A at the LHC, and present accurate theoretical predictions for its inclusive cross section in gluon fusion. The prediction is based on combining fixed-order perturbation theory and all-order threshold resummation. At fixed order we include the exact next-to-next-to-leading order (NNLO) plus an approximate next-to-next-to-next-to-leading order (N^3LO_A) which is based on the recent computation at this order for the scalar case. We then add threshold resummation at next-to-next-to-next-to leading logarithmic accuracy (N^3LL^' ). Various forms of threshold resummation are considered, differing by the treatment of subleading terms, allowing a robust estimate of the theoretical uncertainties due to missing higher orders. With particular attention to pseudo-scalar masses of 200 and 750 GeV, we also observe that perturbative convergence is much improved when resummation is included. Additionally, results obtained with threshold resummation in direct QCD are compared with analogous results as computed in soft-collinear effective theory, which turn out to be in good agreement. We provide precise predictions for pseudo-scalar inclusive cross section at 13 TeV LHC for a wide range of masses. The results are available through updated versions of the public codes ggHiggs and TROLL.

  1. 3D Building Modeling in LoD2 Using the CityGML Standard

    NASA Astrophysics Data System (ADS)

    Preka, D.; Doulamis, A.

    2016-10-01

    Over the last decade, scientific research has been increasingly focused on the third dimension in all fields and especially in sciences related to geographic information, the visualization of natural phenomena and the visualization of the complex urban reality. The field of 3D visualization has achieved rapid development and dynamic progress, especially in urban applications, while the technical restrictions on the use of 3D information tend to subside due to advancements in technology. A variety of 3D modeling techniques and standards has already been developed, as they gain more traction in a wide range of applications. Such a modern standard is the CityGML, which is open and allows for sharing and exchanging of 3D city models. Within the scope of this study, key issues for the 3D modeling of spatial objects and cities are considered and specifically the key elements and abilities of CityGML standard, which is used in order to produce a 3D model of 14 buildings that constitute a block at the municipality of Kaisariani, Athens, in Level of Detail 2 (LoD2), as well as the corresponding relational database. The proposed tool is based upon the 3DCityDB package in tandem with a geospatial database (PostgreSQL w/ PostGIS 2.0 extension). The latter allows for execution of complex queries regarding the spatial distribution of data. The system is implemented in order to facilitate a real-life scenario in a suburb of Athens.

  2. Thymoquinone suppresses migration of LoVo human colon cancer cells by reducing prostaglandin E2 induced COX-2 activation

    PubMed Central

    Hsu, Hsi-Hsien; Chen, Ming-Cheng; Day, Cecilia Hsuan; Lin, Yueh-Min; Li, Shin-Yi; Tu, Chuan-Chou; Padma, Viswanadha Vijaya; Shih, Hui-Nung; Kuo, Wei-Wen; Huang, Chih-Yang

    2017-01-01

    AIM To identify potential anti-cancer constituents in natural extracts that inhibit cancer cell growth and migration. METHODS Our experiments used high dose thymoquinone (TQ) as an inhibitor to arrest LoVo (a human colon adenocarcinoma cell line) cancer cell growth, which was detected by cell proliferation assay and immunoblotting assay. Low dose TQ did not significantly reduce LoVo cancer cell growth. Cyclooxygenase 2 (COX-2) is an enzyme that is involved in the conversion of arachidonic acid into prostaglandin E2 (PGE2) in humans. PGE2 can promote COX-2 protein expression and tumor cell proliferation and was used as a control. RESULTS Our results showed that 20 μmol/L TQ significantly reduced human LoVo colon cancer cell proliferation. TQ treatment reduced the levels of p-PI3K, p-Akt, p-GSK3β, and β-catenin and thereby inhibited the downstream COX-2 expression. Results also showed that the reduction in COX-2 expression resulted in a reduction in PGE2 levels and the suppression of EP2 and EP4 activation. Further analysis showed that TG treatment inhibited the nuclear translocation of β-catenin in LoVo cancer cells. The levels of the cofactors LEF-1 and TCF-4 were also decreased in the nucleus following TQ treatment in a dose-dependent manner. Treatment with low dose TQ inhibited the COX-2 expression at the transcriptional level and the regulation of COX-2 expression efficiently reduced LoVo cell migration. The results were further verified in vivo by confirming the effects of TQ and/or PGE2 using tumor xenografts in nude mice. CONCLUSION TQ inhibits LoVo cancer cell growth and migration, and this result highlights the therapeutic advantage of using TQ in combination therapy against colorectal cancer. PMID:28275297

  3. Effects of anaesthesia on proliferation, invasion and apoptosis of LoVo colon cancer cells in vitro.

    PubMed

    Xu, Y J; Li, S Y; Cheng, Q; Chen, W K; Wang, S L; Ren, Y; Miao, C H

    2016-02-01

    Tumour cell proliferation, invasion and apoptosis are crucial steps in tumour metastasis. We evaluated the effect of serum from patients undergoing colon cancer surgery receiving thoracic epidural and propofol anaesthesia on colon cancer cell biology. Patients were randomly assigned to receive propofol anaesthesia with a concomitant thoracic epidural (PEA, n = 20) or sevoflurane anaesthesia with opioid analgesia (SGA, n = 20). Venous blood was obtained before induction of anaesthesia and 24 hours postoperatively. The LoVo colon cancer cells were cultured with patient serum from both groups and the effects on proliferation, invasion and apoptosis were measured. Twenty-four hours after surgery, the absorbance value of LoVo cells at 10% serum concentration from PEA was decreased when compared with SGA (0.302 (0.026) vs 0.391 (0.066), p = 0.005). The inhibitory rate of LoVo cells at 10% serum concentration from PEA was higher than that from SGA (p = 0.004) 24 h after surgery. The number of invasive LoVo cells at 10% serum concentration from PEA was reduced when compared with SGA (44 (4) vs 62 (4), p < 0.001). Exposure of LoVo cells to postoperative serum from patients receiving PEA led to a higher luminescence ratio (apoptosis) than those receiving SGA (0.36 (0.04) vs 0.27 (0.05), p < 0.001). Serum from patients receiving PEA for colon cancer surgery inhibited proliferation and invasion of LoVo cells and induced apoptosis in vitro more than that from patients receiving SGA. Anaesthetic technique might influence the serum milieu in a way that affects cancer cell biology and, thereby, tumour metastastasis.

  4. 2-D and 3-D Heliospheric Imaging from LEO, L1 and L5: Instruments, Vantage Points, and Applications

    NASA Astrophysics Data System (ADS)

    DeForest, C. E.

    2015-12-01

    Heliospheric imaging has come of age scientifically, and multiple heliospheric imagers are either operating or being built to operate on scientific missions. Much study and effort has been put into the advantages of solar wind imaging for space weather prediction. For example, CME tracking (either in 3-D with polarization, or in an image plane from a vantage far from Earth) has the potential to greatly increase arrival time predictions. Likewise, higher spatial and temporal resolution could provide critical clues about the important N/S component of the entrained magnetic field, by connecting signed surface magnetograms of the Sun to particular structures observed in the corona and, later, in the ICME. I will discuss the current state of understanding of polarized and/or high resolution heliospheric imaging as it relates to space weather forecasting, the relative advantages of an instrument at LEO, L1, or L5, and desiderata to exploit currently-validated and under-consideration techniques in an operational, prototype, or scientific next-generation solar wind imaging experiment.

  5. Lunar Occultations, Setting the Stage for VLTI: The Case Study of CW-Leo (aka IRC+10216)

    NASA Astrophysics Data System (ADS)

    Käufl, Hans Ulrich; Stecklum, Bringfried; Richter, Steffen; Richichi, Andrea

    Lunar occultation allows for a sneak preview of what the VLTI will observe, both with comparable angular resolution and sensitivity. In the thermal infrared ( λ ≈ 10μ m, angular resolution ≤ 0.03^' ') the technique has been pioneered with TIMMI on La Silla. Using this technique several dust shells around Asymptotic Giant Branch stars have been resolved. For the Carbon star CW-Leo (IRC+10 216) high S/N scans will allow for `11/2-dimensional' imaging of the source. At the present state of data reduction the light curves already provide for a very convincing proof of theories on the milli-arcsec scale. In combination with VLTI the technique allows for checks of the visibility calibration and related issues. Moreover, in the (u,v)-plane both techniques are extremely complementary, so that a merging of the data sets appear highly desirable. At La Silla and Paranal ESO a suite of instruments which can be (ab)used for this project is under construction.

  6. Prevalence and Risk Factors for Mycobacterium bovis Infection in African Lions ( Panthera leo ) in the Kruger National Park.

    PubMed

    Sylvester, Tashnica Taime; Martin, Laura Elizabeth Rosen; Buss, Peter; Loxton, Andre Gareth; Hausler, Guy Anton; Rossouw, Leana; van Helden, Paul; Parsons, Sven David Charles; Olea-Popelka, Francisco; Miller, Michele Ann

    2017-04-01

    Mycobacterium bovis, the causative agent of bovine tuberculosis (BTB), is endemic in the Kruger National Park (KNP), South Africa. African lions ( Panthera leo ) are susceptible to BTB, but the impact of the disease on lion populations is unknown. In this study, we used a novel gene expression assay for chemokine (C-X-C motif) ligand 9 (CXCL9) to measure the prevalence of M. bovis infection in 70 free-ranging lions that were opportunistically sampled in the southern and central regions of the KNP. In the southern region of the KNP, the apparent prevalence of M. bovis infection was 54% (95% confidence interval [CI]=36.9-70.5%), compared with 33% (95% CI=18.0-51.8%) in the central region, an important difference (P=0.08). Prevalence of M. bovis infection in lions showed similar patterns to estimated BTB prevalence in African buffaloes ( Syncerus caffer ) in the same areas. Investigation of other risk factors showed a trend for older lions, males, or lions with concurrent feline immunodeficiency virus infection to have a higher M. bovis prevalence. Our findings demonstrate that the CXCL9 gene expression assay is a useful tool for the determination of M. bovis status in free-ranging lions and identifies important epidemiologic trends for future studies.

  7. Space Radiation Environment Prediction for VLSI microelectronics devices onboard a LEO Satellite using OMERE-Trad Software

    NASA Astrophysics Data System (ADS)

    Sajid, Muhammad

    This tutorial/survey paper presents the assessment/determination of level of hazard/threat to emerging microelectronics devices in Low Earth Orbit (LEO) space radiation environment with perigee at 300 Km, apogee at 600Km altitude having different orbital inclinations to predict the reliability of onboard Bulk Built-In Current Sensor (BBICS) fabricated in 350nm technology node at OptMA Lab. UFMG Brazil. In this context, the various parameters for space radiation environment have been analyzed to characterize the ionizing radiation environment effects on proposed BBICS. The Space radiation environment has been modeled in the form of particles trapped in Van-Allen radiation belts(RBs), Energetic Solar Particles Events (ESPE) and Galactic Cosmic Rays (GCR) where as its potential effects on Device- Under-Test (DUT) has been predicted in terms of Total Ionizing Dose (TID), Single-Event Effects (SEE) and Displacement Damage Dose (DDD). Finally, the required mitigation techniques including necessary shielding requirements to avoid undesirable effects of radiation environment at device level has been estimated /determined with assumed standard thickness of Aluminum shielding. In order to evaluate space radiation environment and analyze energetic particles effects on BBICS, OMERE toolkit developed by TRAD was utilized.

  8. Understanding Societies from Inside the Organisms. Leo Pardi's Work on Social Dominance in Polistes Wasps (1937-1952).

    PubMed

    Caniglia, Guido

    2015-08-01

    Leo Pardi (1915-1990) was the initiator of ethological research in Italy. During more than 50 years of active scientific career, he gave groundbreaking contributions to the understanding of social life in insects, especially in Polistes wasps, an important model organism in sociobiology. In the 1940s, Pardi showed that Polistes societies are organized in a linear social hierarchy that relies on reproductive dominance and on the physiological and developmental mechanisms that regulate it, i.e. on the status of ovarian development of single wasps. Pardi's work set the stage for further research on the regulatory mechanisms governing social life in primitively eusocial organisms both in wasps and in other insect species. This article reconstructs Pardi's investigative pathway between 1937 and 1952 in the context of European ethology and American animal sociology. This reconstruction focuses on the development of Pardi's physiological approach and presents a new perspective on the interacting development of these two fields at the origins of our current understanding of animal social behavior.

  9. Accumulation of perfluorinated compounds in captive Bengal tigers (Panthera tigris tigris) and African lions (Panthera leo Linnaeus) in China.

    PubMed

    Li, Xuemei; Yeung, Leo Wai Yin; Taniyasu, Sachi; Lam, Paul K S; Yamashita, Nobuyoshi; Xu, Muqi; Dai, Jiayin

    2008-11-01

    The accumulation of perfluorinated compounds (PFCs) in the sera of captive wildlife species Bengal tigers (Panthera tigris tigris) and African lions (Panthera leo Linnaeus) from Harbin Wildlife Park, Heilongjiang Province, in China were analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Perfluorooctanesulfonate (PFOS) was the predominant contaminant with a mean serum concentration of 1.18 ng mL(-1) in tigers and 2.69 ng mL(-1) in lions. Perfluorononanoic acid (PFNA) was the second most prevalent contaminant in both species. The composition profiles of the tested PFCs differed between tigers and lions, and the percentages of perfluorooctanoic acid (PFOA) were greater in lions than in tigers, indicating different exposures and/or metabolic capabilities between the two species. Assessments of the risk of PFC contamination to the two species were obtained by comparing measured concentrations to points of departure or toxicity reference values (TRVs). Results suggest no risk of PFOS exposure or toxicity for the two species.

  10. Chemical characterization of milk oligosaccharides of an African lion (Panthera leo) and a clouded leopard (Neofelis nebulosa).

    PubMed

    Senda, Akitsugu; Hatakeyama, Emi; Kobayashi, Rui; Fukuda, Kenji; Uemura, Yusuke; Saito, Tadao; Packer, Craig; Oftedal, Olav T; Urashima, Tadasu

    2010-12-01

    The Carnivora include the superfamilies Canoidea and Feloidea. In species of Canoidea other than the domestic dog, Canis lupus, the milk contains only traces of lactose and much larger concentrations of oligosaccharides. In this study, lactose was found to be the dominant saccharide in the milk or colostrum of two species of Feloidea, namely the African lion (Panthera leo) and the clouded leopard (Neofelis nebulosa). In addition to lactose, the following oligosaccharides were characterized in the milk of a lion; Neu5Gc(α2-3)Gal(β1-4)Glc (3'-NGc-SL), Fuc(α1-2)Gal(β1-4)Glc (2'-fucosyllactose) and GalNAc(α1-3)[Fuc(α1-2)]Gal(β1-4)Glc (A-tetrasaccharide). The colostrum of a clouded leopard contained 3'-NGc-SL, Gal(α1-3)Gal(β1-4)Glc (isoglobotriose) and A-tetrasaccharide. These oligosaccharides differ in some respects from those previously identified in another species of Feloidea, the spotted hyena (Crocuta crocuta). These milks contained 3'-NGc-SL and A-tetrasaccharide, while spotted hyena colostrum did not; however, it contained Neu5Ac(α2-3)Gal(β1-4)Glc (3'-NAc-SL) and Gal(α1-3)[Fuc(α1-2)]Gal(β1-4)Glc (B-tetrasaccharide).

  11. The Power of Wide Field HI Surveys: ALFALFA Imaging of Massive Tidal Features in the Leo Cloud of Galaxies

    NASA Astrophysics Data System (ADS)

    Leisman, Luke; Haynes, Martha P.; Giovanelli, Riccardo; ALFALFA Almost Darks Team

    2016-01-01

    Tidal interactions are well known to play an important role in galactic evolution in group environments, but the extent of these interactions, and their relative impact on the morphology-density relation is still unclear. Neutral hydrogen (HI) mapping can reveal the recent interaction history of group galaxies, but is difficult to execute due to the need for high sensitivity over wide fields. The Arecibo Legacy Fast ALFA survey (ALFALFA; Giovanelli et al. 2005; Haynes et al. 2011) provides high sensitivity, unbiased, wide field maps of HI in the local volume; here we will present a 50 deg2 ALFALFA map of a well studied region of the Leo Cloud of galaxies, which includes the NGC3226/7 group and HCG44. These observations reveal HI tails and plumes with extents exceeding 1.4 deg (~600 kpc), well beyond the primary beams of previous observations. These tails constitute a significant fraction of the total HI mass in NGC3226/7 (Arp 94) and HCG44. We will also present WSRT maps of the extended emission near Arp 94, which show tail morphologies inconsistent with 2 body interactions. These observations demonstrate that large scale group interactions will be an important science outcome for future sensitive, wide field HI surveys.This work is supported by NSF grants AST-0607007 and AST-1107390 and by grants from the Brinson Foundation.

  12. Sensitivity and specificity of a nested polymerase chain reaction for detection of lentivirus infection in lions (Panthera leo).

    PubMed

    Adams, Hayley; van Vuuren, Moritz; Kania, Stephen; Bosman, Anna-Mari; Keet, Dewald; New, John; Kennedy, Melissa

    2010-12-01

    Feline immunodeficiency virus (FIV) is a lentivirus in the Retroviridae family that causes lifelong infection in domestic cats. The lentivirus of African lions (Panthera leo), referred to as FIVple, is endemic in certain lion populations in eastern and southern Africa. Lentivirus infection leads to immunologic dysfunction and immunosuppressive disease in domestic cats; however, little is known about the pathogenic effects of infection in lions, nor about the epidemiologic impact on free-ranging and captive populations. Whole blood and serum samples were collected opportunistically from free-ranging lions in Kruger National Park, Republic of South Africa (RSA). Whole blood and serum samples were also collected from captive wild lions in the RSA. A nested polymerase chain reaction (PCR) assay for detection of FIV was performed on all whole blood samples. In addition, serum samples were tested for cross-reactive antibodies to domestic feline lentivirus antigens and puma lentivirus synthetic envelope peptide antigen. The PCR assay successfully amplified the lion lentivirus from African lions. The relative sensitivity and relative specificity were 79% and 100%, respectively, and the positive and negative predictive values were 100% and 67%, respectively. This research represents the first study to compare genetic material with antibody-based methods of lentivirus detection on lions in RSA. Using PCR as an additional diagnostic test for FIV in lions will increase screening sensitivity and will allow viral characterization among circulating isolates and monitoring of changes in the viral epidemiology within geographic regions and populations over time.

  13. Retrospective study of mortality in Asiatic lions (Panthera leo persica) in the European breeding population between 2000 and 2014.

    PubMed

    Metz, Olivia; Williams, Jonathan; Nielsen, Rikke Kruse; Masters, Nic

    2017-01-01

    Although the European population of Asiatic lions (Panthera leo persica) has been managed under the European Endangered Species Program (EEP) since 1990, little is known about the health status of the population. This study was designed to characterize mortality for this population through examination of the studbook and other records on 392 Asiatic lions living in the EEP between 2000 and 2014. A total of 270 animals died during the period with 80% of them being under 1 year old. The mortality rate for under 1 year olds was 54%, while the odds of survival of cubs within a litter increased if the dam had had litters previously. Survival to reproductive age was 44%. Post-mortem reports were requested and the cause of death was obtained for 133 animals. Trauma inflicted by a conspecific and lack of care were common causes of death (26% and 22%, respectively) and were also responsible for most of the neonatal mortalities. Congenital defects were responsible for 9% of deaths, although the true prevalence is likely underestimated. A common necropsy protocol for all Asiatic lion collections is needed to facilitate future studies. Zoo Biol. 36:66-73, 2017. © 2017 Wiley Periodicals, Inc.

  14. Phylogeography of lions (Panthera leo ssp.) reveals three distinct taxa and a late Pleistocene reduction in genetic diversity.

    PubMed

    Barnett, Ross; Shapiro, Beth; Barnes, Ian; Ho, Simon Y W; Burger, Joachim; Yamaguchi, Nobuyuki; Higham, Thomas F G; Wheeler, H Todd; Rosendahl, Wilfried; Sher, Andrei V; Sotnikova, Marina; Kuznetsova, Tatiana; Baryshnikov, Gennady F; Martin, Larry D; Harington, C Richard; Burns, James A; Cooper, Alan

    2009-04-01

    Lions were the most widespread carnivores in the late Pleistocene, ranging from southern Africa to the southern USA, but little is known about the evolutionary relationships among these Pleistocene populations or the dynamics that led to their extinction. Using ancient DNA techniques, we obtained mitochondrial sequences from 52 individuals sampled across the present and former range of lions. Phylogenetic analysis revealed three distinct clusters: (i) modern lions, Panthera leo; (ii) extinct Pleistocene cave lions, which formed a homogeneous population extending from Europe across Beringia (Siberia, Alaska and western Canada); and (iii) extinct American lions, which formed a separate population south of the Pleistocene ice sheets. The American lion appears to have become genetically isolated around 340 000 years ago, despite the apparent lack of significant barriers to gene flow with Beringian populations through much of the late Pleistocene. We found potential evidence of a severe population bottleneck in the cave lion during the previous interstadial, sometime after 48 000 years, adding to evidence from bison, mammoths, horses and brown bears that megafaunal populations underwent major genetic alterations throughout the last interstadial, potentially presaging the processes involved in the subsequent end-Pleistocene mass extinctions.

  15. Simulation study for the determination of the lunar gravity field from PRARE-L tracking onboard the German LEO mission

    NASA Astrophysics Data System (ADS)

    Flechtner, Frank; Neumayer, Karl Hans; Kusche, Jürgen; Schäfer, Wolfgang; Sohl, Frank

    2008-10-01

    A simulation study has been performed at GFZ Potsdam, which shows the anticipated improvement of the lunar gravity field model with respect to current (LP150Q model) or near-future (SELENE) knowledge in the framework of the planned German Lunar Explorations Orbiter (LEO) mission, based on PRARE-L (Precise Range And Range-rate Equipment - Lunar version) Satellite-to-Satellite (SST) and Satellite-Earth-Satellite (SEST) tracking observations. It is shown that the global mean error of the lunar gravity field can be reduced to less than 0.1 mGal at a spatial resolution of 50 km. In the spectral domain, this means a factor of 10 (long wavelengths) and some 100 (mid to short wavelengths) improvement as compared to predictions for SELENE or a factor of 1000 with respect to LP150Q. Furthermore, a higher spatial resolution of up to 28 km seems feasible and would correspond to a factor of 2-3 improvement of SELENE results. Moreover, PRARE-L is expected to derive the low-degree coefficients of the lunar gravity field with unprecedented accuracy. Considering long mission duration (at least 1 year is planned) this would allow for the first time a precise direct determination of the low-degree tidal Love numbers of the Moon and, in combination with high precision SEST, would provide an experimental basis to study relativistic effects such as the periselenium advance in the Earth-Moon system.

  16. Genetic diversity affects testicular morphology in free-ranging lions (Panthera leo) of the Serengeti Plains and Ngorongoro Crater.

    PubMed

    Munson, L; Brown, J L; Bush, M; Packer, C; Janssen, D; Reiziss, S M; Wildt, D E

    1996-09-01

    Reduced genetic variability is known to adversely affect ejaculate quality in inbred lions (Panthera leo) physically isolated in the Ngorongoro Crater compared with outbred lions inhabiting the adjacent Serengeti Plains in East Africa. This study compared the histomorphology of testicular biopsies from these two lion populations. Ngorongoro Crater lions had fewer (P < 0.05) seminiferous tubules with spermiogenesis and fewer (P < 0.05) spermatids per seminiferous tubular cross-section than Serengeti Plains lions, although seminiferous tubular diameter did not differ (P > 0.05) between populations. Interstitial areas were greater (P < 0.05) in Crater than in Plains lions, but no qualitative differences were evident, suggesting that proportionately less testicular area was occupied by seminiferous tubules in Crater lions. None of the lions in either population had evidence of testicular degeneration. Overall results suggest that inbred Crater lions have reduced spermiogenesis and less total seminiferous tubular area per testis. These data further support the premise that genetic homogeneity compromises reproductive traits in free-living, male African lions.

  17. Cellular stress induced by photodynamic reaction with CoTPPS and MnTMPyPCl5 in combination with electroporation in human colon adenocarcinoma cell lines (LoVo and LoVoDX).

    PubMed

    Kulbacka, J; Kotulska, M; Rembiałkowska, N; Choromańska, A; Kamińska, I; Garbiec, A; Rossowska, J; Daczewska, M; Jachimska, B; Saczko, J

    2013-11-01

    Two porphyrins, CoTPPS and MnTMPyPCl5, were tested for their photodynamic activity and potential novel use in a therapy of human cancers. We investigated an effect of photodynamic reaction (PDR), electroporation (EP) and their combination (electro-photodynamic reaction [EP-PDR]) on human colon adenocarcinoma cell lines (LoVo and resistant to doxorubicin LoVoDX), human breast adenocarcinoma (wild type MCF-7/WT and resistant to doxorubicin MCF-7/DOX), and human melanoma (Me45). The efficiency of macromolecules transport was examined with cytofluorymetry by assessing the degree of propidium iodide (PI) penetration. Additionally, cellular ultrastructure after EP was evaluated. We determined cyto- and photo-cytotoxic effect on the cells viability (MTT assay) after standard PDR and PDR combined with EP. Intracellular distribution and mitochondrial colocalization of both porphyrins was also performed. The experiments proved that both complexes exhibit desirable photodynamic properties on LoVo LoVoDX cells, and EP effectively supports photodynamic method in this type of cancer. The application of EP provided shorter time of incubation (only 10 min) and enhanced effect of applied therapy. The porphyrins did not affect the MCF-7 and Me45 cell lines.

  18. Balm mint extract (Lo-701) for topical treatment of recurring herpes labialis.

    PubMed

    Koytchev, R; Alken, R G; Dundarov, S

    1999-10-01

    A double-blind, placebo-controlled, randomized trial was carried out with the aim of proving efficacy of standardized balm mint cream [active ingredient: 1% Lo-701--dried extract from Melissa officinalis L. leaves (70:1)] for the therapy of herpes simplex labialis. Sixty six patients with a history of recurrent herpes labialis (at least four episodes per year) in one center were treated topically; 34 of them with verum and 32 with placebo. The cream had to be smeared on the affected area four times daily over five days. A combined symptom score of the values for complaints, size of affected area and blisters at day 2 of therapy was formed as the primary target parameter. There was a significant difference in the values of the primary target parameter between both treatment groups: verum 4.03 +/- 0.33 (3.0); placebo 4.94 +/- 0.40 (5.0); values given are mean +/- SEM (median) of the symptoms score on day 2 of therapy. The tested formulation is effective for the treatment of herpes simplex labialis. The significant difference in the combined symptom score on the second day of treatment is of particular importance having in mind that the complaints in patients suffering from herpes labialis are usually most intensive at that time. In addition to the shortening of the healing period, the prevention of a spreading of the infection and the rapid effect on typical symptoms of herpes like itching, tingling, burning, stabbing, swelling, tautness and erythema, the balm mint cream has a further advantage. The different mechanism of action of the balm mint extract rules out the development of resistance of the herpes virus. Some indication exists that the intervals between the periods with herpes might be prolonged with balm mint cream treatment.

  19. Spark Ignition Characteristics of a LO2/LCH4 Engine at Altitude Conditions

    NASA Technical Reports Server (NTRS)

    Kleinhenz, Julie; Sarmiento, Charles; Marshall, William

    2012-01-01

    The use of non-toxic propellants in future exploration vehicles would enable safer, more cost effective mission scenarios. One promising "green" alternative to existing hypergols is liquid methane/liquid oxygen. To demonstrate performance and prove feasibility of this propellant combination, a 100lbf LO2/LCH4 engine was developed and tested under the NASA Propulsion and Cryogenic Advanced Development (PCAD) project. Since high ignition energy is a perceived drawback of this propellant combination, a test program was performed to explore ignition performance and reliability versus delivered spark energy. The sensitivity of ignition to spark timing and repetition rate was also examined. Three different exciter units were used with the engine's augmented (torch) igniter. Propellant temperature was also varied within the liquid range. Captured waveforms indicated spark behavior in hot fire conditions was inconsistent compared to the well-behaved dry sparks (in quiescent, room air). The escalating pressure and flow environment increases spark impedance and may at some point compromise an exciter.s ability to deliver a spark. Reduced spark energies of these sparks result in more erratic ignitions and adversely affect ignition probability. The timing of the sparks relative to the pressure/flow conditions also impacted the probability of ignition. Sparks occurring early in the flow could trigger ignition with energies as low as 1-6mJ, though multiple, similarly timed sparks of 55-75mJ were required for reliable ignition. An optimum time interval for spark application and ignition coincided with propellant introduction to the igniter and engine. Shifts of ignition timing were manifested by changes in the characteristics of the resulting ignition.

  20. More food, low pollution (mo fo lo Po): a grand challenge for the 21st century.

    PubMed

    Davidson, Eric A; Suddick, Emma C; Rice, Charles W; Prokopy, Linda S

    2015-03-01

    Synthetic nitrogen fertilizer has been a double-edged sword, greatly improving human nutrition during the 20th century but also posing major human health and environmental challenges for the 21st century. In August 2013, about 160 agronomists, scientists, extension agents, crop advisors, economists, social scientists, farmers, representatives of regulatory agencies and nongovernmental organizations (NGOs), and other agricultural experts gathered to discuss the vexing challenge of how to produce more food to nourish a growing population while minimizing pollution to the environment. This collection of 14 papers authored by conference participants provides a much needed analysis of the many technical, economic, and social impediments to improving nitrogen use efficiency (NUE) in crop and animal production systems. These papers demonstrate that the goals of producing more food with low pollution (Mo Fo Lo Po) will not be achieved by technological developments alone but will also require policies that recognize the economic and social factors affecting farmer decision-making. Take-home lessons from this extraordinary interdisciplinary effort include the need (i) to develop partnerships among private and public sectors to demonstrate the most current, economically feasible, best management NUE practices at local and regional scales; (ii) to improve continuing education to private sector retailers and crop advisers; (iii) to tie nutrient management to performance-based indicators on the farm and in the downwind and downstream environment; and (iv) to restore investments in research, education, extension, and human resources that are essential for developing the interdisciplinary knowledge and innovative skills needed to achieve agricultural sustainability goals.

  1. CXCR6 marks a novel subset of T-bet(lo)Eomes(hi) natural killer cells residing in human liver.

    PubMed

    Stegmann, Kerstin A; Robertson, Francis; Hansi, Navjyot; Gill, Upkar; Pallant, Celeste; Christophides, Theodoros; Pallett, Laura J; Peppa, Dimitra; Dunn, Claire; Fusai, Giuseppe; Male, Victoria; Davidson, Brian R; Kennedy, Patrick; Maini, Mala K

    2016-05-23

    Natural killer cells (NK) are highly enriched in the human liver, where they can regulate immunity and immunopathology. We probed them for a liver-resident subset, distinct from conventional bone-marrow-derived NK. CXCR6+ NK were strikingly enriched in healthy and diseased liver compared to blood (p < 0.0001). Human hepatic CXCR6+ NK had an immature phenotype (predominantly CD56(bright)CD16-CD57-), and expressed the tissue-residency marker CD69. CXCR6+ NK produced fewer cytotoxic mediators and pro-inflammatory cytokines than the non-liver-specific CXCR6- fraction. Instead CXCR6+ NK could upregulate TRAIL, a key death ligand in hepatitis pathogenesis. CXCR6 demarcated liver NK into two transcriptionally distinct populations: T-bet(hi)Eomes(lo)(CXCR6-) and T-bet(lo)Eomes(hi)(CXCR6+); the latter was virtually absent in the periphery. The small circulating CXCR6+ subset was predominantly T-bet(hi)Eomes(lo), suggesting its lineage was closer to CXCR6- peripheral than CXCR6+ liver NK. These data reveal a large subset of human liver-resident T-bet(lo)Eomes(hi) NK, distinguished by their surface expression of CXCR6, adapted for hepatic tolerance and inducible anti-viral immunity.

  2. Circulating CXCR5+CXCR3+PD-1lo Tfh-like cells in HIV-1 controllers with neutralizing antibody breadth

    PubMed Central

    Martin-Gayo, Enrique; Cronin, Jacqueline; Hickman, Taylor; Ouyang, Zhengyu; Lindqvist, Madelene; Kolb, Kellie E.; Schulze zur Wiesch, Julian; Cubas, Rafael; Porichis, Filippos; Shalek, Alex K.; van Lunzen, Jan; Haddad, Elias K.; Walker, Bruce D.; Kaufmann, Daniel E.; Lichterfeld, Mathias; Yu, Xu G.

    2017-01-01

    HIV-1–specific broadly neutralizing antibodies (bnAbs) typically develop in individuals with continuous high-level viral replication and increased immune activation, conditions that cannot be reproduced during prophylactic immunization. Understanding mechanisms supporting bnAb development in the absence of high-level viremia may be important for designing bnAb-inducing immunogens. Here, we show that the breadth of neutralizing antibody responses in HIV-1 controllers was associated with a relative enrichment of circulating CXCR5+CXCR3+PD-1lo CD4+ T cells. These CXCR3+PD-1lo Tfh-like cells were preferentially induced in vitro by functionally superior dendritic cells from controller neutralizers, and able to secrete IL-21 and support B cells. In addition, these CXCR3+PD-1lo Tfh-like cells contained higher proportions of stem cell–like memory T cells, and upon antigenic stimulation differentiated into PD-1hi Tfh-like cells in a Notch-dependent manner. Together, these data suggest that CXCR5+CXCR3+PD-1lo cells represent a dendritic cell–primed precursor cell population for PD-1hi Tfh-like cells that may contribute to the generation of bnAbs in the absence of high-level viremia. PMID:28138558

  3. Nonlinear Analysis of the Space Shuttle Superlightweight LO2 Tank. Part 1; Bahavior Under Booster Ascent Loads

    NASA Technical Reports Server (NTRS)

    Young, Richard D.; Nemeth, Michael P.; Collins, Timothy J.; Starnes, James H., Jr.

    1998-01-01

    Results of linear bifurcation and nonlinear analyses of the Space Shuttle superlightweight (SLWT) external liquid-oxygen (LO2) tank for an important early booster ascent loading condition are presented. These results for thin-walled linear elastic shells that are subjected to combined mechanical and thermal loads illustrate an important type of response mode that may be encountered in the design of other liquid-fuel launch vehicles. Linear bifurcation analyses are presented that predict several nearly equal eigenvalues that correspond to local buckling modes in the forward ogive section of the LO2 tank. In contrast, the nonlinear response phenomenon is shown to consist of short-wavelength bending deformations in the forward ogive and barrel sections of the LO2 tank that growing amplitude in a stable manner increasing load. Imperfection sensitivity analyses are presented that show that the presence of several nearly equal eigenvalues does not lead to a premature general instability mode for the forward ogive section. For the linear bifurcation and nonlinear analyses, the results show that accurate predictions of the response of the shield generally require a large-scale, high-fidelity finite-element model. Results are also presented that show that the SLWT LO2 tank can support loads in excess of approximately 2.6 times the values of the operational loads considered.

  4. The LO Model and the Traditional French Organisational Culture: A Paradigmatic Contradiction Leading to a Limited Implementation

    ERIC Educational Resources Information Center

    Belet, Daniel

    2010-01-01

    This article deals with the issue of the very weak implementation of the LO model in France, although it appears as an appealing new management paradigm that can allow companies to better face a fast changing environment. The author argues that there is a strong philosophical contradiction between this innovative management model and the still…

  5. Volatile organic compound fluxes and concentrations in London (ClearfLo)

    NASA Astrophysics Data System (ADS)

    Valach, Amy; Langford, Ben; Nemitz, Eiko; MacKenzie, Rob; Hewitt, Nick

    2014-05-01

    Volatile organic compounds (VOCs) from anthropogenic sources such as fuel combustion or evaporative emissions can directly and indirectly affect human health. Some VOCs, such as benzene and 1,3- butadiene are carcinogens. These and other VOCs contribute to the formation of ozone (O3) and aerosol particles, which have effects on human health and the radiative balance of the atmosphere. Although in the UK VOC emissions are subject to control under European Commission Directive 2008/50/EC and emission reducing technologies have been implemented, urban air pollution remains a concern. Urban air quality is likely to remain a priority since currently >50% of the global population live in urban areas with trends in urbanization and population migration predicted to increase. The ClearfLo project is a large multi-institutional consortium funded by the UK Natural Environment Research Council (NERC) and provides integrated measurements of meteorology, gas phase and particulate composition of the atmosphere over London. Both long term and IOP measurements were made at street and elevated locations at a range of sites across London and its surroundings during 2011 and 2012. Mixing ratios of a selection of nine VOCs were measured using a high sensitivity proton transfer reaction-mass spectrometer (PTR-MS) at a ground level urban background (North Kensington) and kerbside (Marylebone Road) site during the winter IOP. VOC fluxes were measured by virtually disjunct eddy covariance (vDEC) at an elevated urban site (King's College Strand) in Aug-Dec 2012. Our results for the first IOP showed that most of the selected compound concentrations depended on traffic emissions, although there was a marked difference between the urban background and kerbside sites. We identified some temperature effects on VOC concentrations. We also present the first analyses of VOC flux measurements over London. Preliminary analyses indicate most compounds associated with vehicle emissions closely

  6. Back Analysis of the 2014 San Leo Landslide Using Combined Terrestrial Laser Scanning and 3D Distinct Element Modelling

    NASA Astrophysics Data System (ADS)

    Spreafico, Margherita Cecilia; Francioni, Mirko; Cervi, Federico; Stead, Doug; Bitelli, Gabriele; Ghirotti, Monica; Girelli, Valentina Alena; Lucente, Claudio Corrado; Tini, Maria Alessandra; Borgatti, Lisa

    2016-06-01

    Landslides of the lateral spreading type, involving brittle geological units overlying ductile terrains, are a common occurrence in the sandstone and limestone plateaux of the northern Apennines of Italy. The edges of these plateaux are often the location of rapid landslide phenomena, such as rock slides, rock falls and topples. In this paper, we present a back analysis of a recent landslide (February 2014), involving the north-eastern sector of the San Leo rock slab (northern Apennines, Emilia-Romagna Region) which is a representative example of this type of phenomena. The aquifer hosted in the fractured slab, due to its relatively higher secondary permeability in comparison to the lower clayey units leads to the development of perennial and ephemeral springs at the contact between the two units. The related piping erosion phenomena, together with slope processes in the clay-shales have led to the progressive undermining of the slab, eventually predisposing large-scale landslides. Stability analyses were conducted coupling terrestrial laser scanning (TLS) and distinct element methods (DEMs). TLS point clouds were analysed to determine the pre- and post-failure geometry, the extension of the detachment area and the joint network characteristics. The block dimensions in the landslide deposit were mapped and used to infer the spacing of the discontinuities for insertion into the numerical model. Three-dimensional distinct element simulations were conducted, with and without undermining of the rock slab. The analyses allowed an assessment of the role of the undermining, together with the presence of an almost vertical joint set, striking sub-parallel to the cliff orientation, on the development of the slope instability processes. Based on the TLS and on the numerical simulation results, an interpretation of the landslide mechanism is proposed.

  7. A technique for synergistic atomic oxygen and vacuum ultraviolet radiation durability evaluation of materials for use in LEO

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Banks, Bruce A.

    1996-01-01

    Material erosion data collected during flight experiments such as the Environmental Oxygen Interaction with Materials (EOIM)-3 and the Long Duration Exposure Facility (LDEF) have raised questions as to the sensitivity of material erosion to levels of atomic oxygen exposure and vacuum ultraviolet (VUV) radiation. The erosion sensitivity of some materials such as FEP Teflon used as a thermal control material on satellites in low Earth orbit (LEO), is particularly important but difficult to determine. This is in large part due to the inability to hold all but one exposure parameter constant during a flight experiment. This is also difficult to perform in a ground based facility, because often the variation of the level of atomic oxygen or VUV radiation also results in a change in the level of the other parameter. A facility has been developed which allows each parameter to be changed almost independently and offer broad area exposure. The resulting samples can be made large enough for mechanical testing. The facility uses an electron cyclotron resonance plasma source to provide the atomic oxygen. A series of glass plates is used to focus the atomic oxygen while filtering the VUV radiation from the plasma source. After filtering, atomic oxygen effective flux levels can still be measured which are as high as 7 x 10(exp 15) atoms/cm(exp 2)-sec which is adequate for accelerated testing. VUV radiation levels after filtering can be as low as 0.3 suns. Additional VUV suns can be added with the use of deuterium lamps which allow the VUV level to be changed while keeping the flux of atomic oxygen constant. This paper discusses the facility, and results from exposure of Kapton and FEP at pre-determined atomic oxygen flux and VUV sun levels.

  8. Requirements for an Advanced Low Earth Orbit (LEO) Sounder (ALS) for Improved Regional Weather Prediction and Monitoring of Greenhouse Gases

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; Chahine, Moustafa T.; Susskind, Joel

    2008-01-01

    Hyperspectral infrared atmospheric sounders (e.g., the Atmospheric Infrared Sounder (AIRS) on Aqua and the Infrared Atmospheric Sounding Interferometer (IASI) on Met Op) provide highly accurate temperature and water vapor profiles in the lower to upper troposphere. These systems are vital operational components of our National Weather Prediction system and the AIRS has demonstrated over 6 hrs of forecast improvement on the 5 day operational forecast. Despite the success in the mid troposphere to lower stratosphere, a reduction in sensitivity and accuracy has been seen in these systems in the boundary layer over land. In this paper we demonstrate the potential improvement associated with higher spatial resolution (1 km vs currently 13.5 km) on the accuracy of boundary layer products with an added consequence of higher yield of cloud free scenes. This latter feature is related to the number of samples that can be assimilated and has also shown to have a significant impact on improving forecast accuracy. We also present a set of frequencies and resolutions that will improve vertical resolution of temperature and water vapor and trace gas species throughout the atmosphere. Development of an Advanced Low Earth Orbit (LEO) Sounder (ALS) with these improvements will improve weather forecast at the regional scale and of tropical storms and hurricanes. Improvements are also expected in the accuracy of the water vapor and cloud properties products, enhancing process studies and providing a better match to the resolution of future climate models. The improvements of technology required for the ALS are consistent with the current state of technology as demonstrated in NASA Instrument Incubator Program and NOAA's Hyperspectral Environmental Suite (HES) formulation phase development programs.

  9. Pride diaries: sex, brain size and sociality in the African lion (Panthera leo) and cougar (Puma concolor).

    PubMed

    Arsznov, Bradley M; Sakai, Sharleen T

    2012-01-01

    The purpose of this study was to examine if differences in social life histories correspond to intraspecific variation in total or regional brain volumes in the African lion (Panthera leo) and cougar (Puma concolor). African lions live in gregarious prides usually consisting of related adult females, their dependent offspring, and a coalition of immigrant males. Upon reaching maturity, male lions enter a nomadic and often, solitary phase in their lives, whereas females are mainly philopatric and highly social throughout their lives. In contrast, the social life history does not differ between male and female cougars; both are solitary. Three-dimensional virtual endocasts were created using computed tomography from the skulls of 14 adult African lions (8 male, 6 female) and 14 cougars (7 male, 7 female). Endocranial volume and basal skull length were highly correlated in African lions (r = 0.59, p < 0.05) and in cougars (r = 0.67, p < 0.01). Analyses of total endocranial volume relative to skull length revealed no sex differences in either African lions or cougars. However, relative anterior cerebrum volume comprised primarily of frontal cortex and surface area was significantly greater in female African lions than males, while relative posterior cerebrum volume and surface area was greater in males than females. These differences were specific to the neocortex and were not found in the solitary cougar, suggesting that social life history is linked to sex-specific neocortical patterns in these species. We further hypothesize that increased frontal cortical volume in female lions is related to the need for greater inhibitory control in the presence of a dominant male aggressor.

  10. Radiologic abnormalities of the appendicular skeleton of the lion (Panthera leo): incidental findings and Mycobacterium bovis-induced changes.

    PubMed

    Kirberger, Robert M; Keet, Dewald F; Wagner, Wencke M

    2006-01-01

    Thoracic and pelvic limbs from 15 euthanized free-ranging lions (Panthera leo), ranging in age from 16 to 144 months, underwent standard radiographic evaluation. All lions had tested positive for Mycobacterium bovis by means of a modified intradermal tuberculn test. The radiographs of six lions were normal and nine had incidental findings of which six had more than one lesion. Seven lions had lesions suspected to be associated with tuberculosis, which was confirmed in specific joints in two lions. Incidental pathology was classified as traumatic injuries and degenerative or trauma-associated joint disease. The traumatic lesions were fractures of which the most remarkable was a femur malunion. Four lions had fibula and another three lions had metacarpal/tarsal and phalangeal fractures. Joint lesions included glenoid, humeral head, and accessory carpal bone osteophytes. There was evidence of a cranial cruciate ligament rupture in an 8-year-old male. Trauma induced joint lesions were seen in four stifles (fragmented or displaced sesamoid bones, fragmented meniscal ossicle, or mineralized fragments). Radiological abnormalities believed to be caused by M. bovis were present in one stifle, one radiocarpal three tibiotarsal, and one tarsometatarsal joints. These had evidence of septic arthritis with extensive bone formation and capsular mineralization. In one 20-month-old lion, changes typical of a bone abscess were found in a proximal tibia. Radiologic evidence of elbow hygromas were seen in three elbows, all believed to be caused by M. bovis. Lions appeared to cope fairly well with a variety of traumatic injuries and were also susceptible to some of the aging/incidental radiologic findings seen in dogs and cats. The suspected M. bovis osseous lesions were more likely to involve the joints, particularly the tarsal joint and were mainly proliferative.

  11. Estimated performance and future potential of solar dynamic and photovoltaic power systems for selected LEO and HEO missions

    NASA Technical Reports Server (NTRS)

    Bents, David J.; Lu, Cheng Y.

    1989-01-01

    Solar Photo Voltaic (PV) and thermal dynamic power systems for application to selected Low Earth Orbit (LEO) and High Eccentric Orbit (Energy) (HEO) missions are characterized in the regime 7 to 35 kWe. Input parameters to the characterization are varied corresponding to anticipated introduction of improved or new technologies. Comparative assessment is made between the two power system types utilizing newly emerging technologies in cells and arrays, energy storage, optical surfaces, heat engines, thermal energy storage, and thermal management. The assessment is made to common ground rules and assumptions. The four missions (space station, sun-synchronous, Van Allen belt and GEO) are representative of the anticipated range of multi-kWe earth orbit missions. System characterizations include all required subsystems, including power conditioning, cabling, structure, to deliver electrical power to the user. Performance is estimated on the basis of three different levels of component technology: (1) state-of-art, (2) near-term, and (3) advanced technologies. These range from planar array silicon/IPV nickel hydrogen batteries and Brayton systems at 1000 K to thin film GaAs with high energy density secondary batteries or regenerative fuel cells and 1300 K Stirling systems with ultra-lightweight concentrators and radiators. The system estimates include design margin for performance degradations from the known environmental mechanisms (micrometeoroids and space debris, atomic oxygen, electron and proton flux) which are modeled and applied depending on the mission. The results give expected performance, mass and drag of multi-kWe earth orbiting solar power systems and show how overall system figures of merit will improve as new component technologies are incorporated.

  12. Evaluation of Error Correcting Code performances of a free space optical communication system between LEO satellite and Ground Station

    NASA Astrophysics Data System (ADS)

    Chochol, M.; Rissons, A.; Lacan, J.; Vedrenne, N.; Artaud, G.

    2015-10-01

    The use of optical communication to transfer data between LEO satellite and optical ground station is being studied. It creates the opportunities to highly increase a transmitted data rate across a free space. The optical propagation channel has specificities that imply the potential use of error correcting code (ECC) and interleaving at physical and higher layer. The study aims to assess the performance of a combination of ECC and interleaving in presence of various channel scenarios and receiver architectures. As a result of these studies, a functional physical layer simulator is provided. The simulator emulates a signal generation and applies time series representing the propagation channel with an effect of receiver front-ends. It also features various detection methods and computes mutual information (MI) in order to approximate ECC performances. A number of receiver architectures and channel scenarios were studied. The channel scenarios combine a direct coupling of the received signal into the photo-detector (PD) and among other assume the use of pre-amplified receiver implying the signal coupling into a standard single mode fiber (SSMF) prior to the detection. Time series were generated and represent the power received at PD input depending on the chosen scenarios (without adaptive optics (AO), with tip-tilt correction, with no dynamical coupling losses or with higher order AO correction). Two modulations of OOK and DBPSK along with various detection methods were examined. The tuning of ECC parameters was studied through the computation of mutual information. Additionally two cases of physical and higher layer interleaving were implemented providing an excellent diversity to the channel seen by the codeword of ECC.

  13. Timescales of partial melting in the Himalayan middle crust: insight from the Leo Pargil dome, northwest India

    NASA Astrophysics Data System (ADS)

    Lederer, Graham W.; Cottle, John M.; Jessup, Micah J.; Langille, Jackie M.; Ahmad, Talat

    2013-11-01

    The Leo Pargil dome (LPD) in northwest India exposes an interconnected network of pre-, syn-, and post-kinematic leucogranite dikes and sills that pervasively intrude amphibolite-facies metapelites of the mid-crustal Greater Himalayan sequence. Leucogranite bodies range from thin (5-cm-wide) locally derived sills to thick (2-m-wide) crosscutting dikes extending at least 100 m. Three-dimensional exposures elucidate crosscutting relations between different phases of melt injection and crystallization. Combined laser ablation inductively coupled plasma mass spectrometry U-Th/Pb geochronology and trace element analysis on well-characterized monazite grains from nineteen representative leucogranites yields a large, internally consistent data set of approximately 700 U-Th/Pb and 400 trace element analyses. Grain-scale variations in age correlate with trace element distributions and indicate semi-continuous crystallization of monazite from 30 to 18 Ma. The youngest U-Th/Pb ages in a given sample are consistent with the outcrop-scale crosscutting relations, whereas older ages within individual samples record inheritance from partially crystallized melt and source metapelites. U-Th/Pb isotopic and trace element data are incorporated into a model of melting within the LPD that involves (1) steady-state equilibrium batch melting of compositionally homogeneous metapelitic sources; (2) pulses of increased melt mobility lasting 1-2 m.y. resulting in segregation of melt from its source and amalgamation into mixed magmas; and (3) rapid emplacement and final crystallization of leucogranite bodies. Melt systems in the LPD evolved from locally derived, in situ melt in migmatitic source rocks into a vast network of dikes and sills in the overlying non-migmatitic host rocks.

  14. Sustainable Systems for exploration, stays with increased duration in LEO and Earth application -an overview about life support activities

    NASA Astrophysics Data System (ADS)

    Slenzka, Klaus; Duenne, Matthias

    Solar system exploration with extended stays in totally closed habitats far away from Earth as well as longer stays in LEO requires intensive preparatory activities. Activities supporting life in a more or less close meaning are essential in this context -on a scientific as well as on a technical level. These needed activities are supporting life by e.g.: i) increasing knowledge about the impact of single and combined effects of different exploration related environmental conditions (e. g. microgravity, radiation, reduced pressure and temperature, lunar soil etc.) on biological systems. This is needed to enable safe life of humans itself as well as safe operating of required bioregenerative life support systems. Thus, different human cell types as well as representatives of bioregenerative life support system protagonists (algae, bacteria as well as higher organisms) needs to be addressed. ii) provision of required consumables (oxygen, food, energy equivalents etc.) on site, mainly via bioregenerative life support systems, Bio-ISRU-units etc. Preparation is needed on a scientific as well as technological level. iii) ensuring reduced negative effects on humans (and partially also equipment), which could be caused by living in a closed habitat in general (and thus being not space related per se): E. g. detection systems for the quality of water and air, antimicrobial and selfhealing as well as anti-icing materials without dangerous hazard substances, psychological health enhancing components etc. Referring payloads for above mentioned investigations (scientific evaluation and technology demonstration) must be developed. Extended stays and extended closure in habitats without the possibility of material transport into and out of the system are leading to the necessity of more autonomous technologies and sustainable processes. Latter one will rely mainly on biological processes and structures, which increases additionally the necessity of an intensive scientific and

  15. Lion (Panthera leo) and caracal (Caracal caracal) type IIx single muscle fibre force and power exceed that of trained humans.

    PubMed

    Kohn, Tertius A; Noakes, Timothy D

    2013-03-15

    This study investigated for the first time maximum force production, shortening velocity (Vmax) and power output in permeabilised single muscle fibres at 12°C from lion, Panthera leo (Linnaeus 1758), and caracal, Caracal caracal (Schreber 1776), and compared the values with those from human cyclists. Additionally, the use and validation of previously frozen tissue for contractile experiments is reported. Only type IIx muscle fibres were identified in the caracal sample, whereas type IIx and only two type I fibres were found in the lion sample. Only pure type I and IIa, and hybrid type IIax fibres were identified in the human samples - there were no pure type IIx fibres. Nevertheless, compared with all the human fibre types, the lion and caracal fibres were smaller (P<0.01) in cross-sectional area (human: 6194±230 μm(2), lion: 3008±151 μm(2), caracal: 2583±221 μm(2)). On average, the felid type IIx fibres produced significantly greater force (191-211 kN m(-2)) and ~3 times more power (29.0-30.3 kN m(-2) fibre lengths s(-1)) than the human IIax fibres (100-150 kN m(-2), 4-11 kN m(-2) fibre lengths s(-1)). Vmax values of the lion type IIx fibres were also higher than those of human type IIax fibres. The findings suggest that the same fibre type may differ substantially between species and potential explanations are discussed.

  16. Construction of a Matched Global Cloud and Radiance Product from LEO/GEO and EPIC Observations to Estimate Daytime Earth Radiation Budget from DSCOVR

    NASA Technical Reports Server (NTRS)

    Duda, David P.; Khlopenkov, Konstantin V.; Thiemann, Mandana; Palikonda, Rabindra; Sun-Mack, Sunny; Minnis, Patrick; Su, Wenying

    2016-01-01

    With the launch of the Deep Space Climate Observatory (DSCOVR), new estimates of the daytime Earth radiation budget can be computed from a combination of measurements from the two Earth-observing sensors onboard the spacecraft, the Earth Polychromatic Imaging Camera (EPIC) and the National Institute of Standards and Technology Advanced Radiometer (NISTAR). Although these instruments can provide accurate top-of-atmosphere (TOA) radiance measurements, they lack sufficient resolution to provide details on small-scale surface and cloud properties. Previous studies have shown that these properties have a strong influence on the anisotropy of the radiation at the TOA, and ignoring such effects can result in large TOA-flux errors. To overcome these effects, high-resolution scene identification is needed for accurate Earth radiation budget estimation. Selected radiance and cloud property data measured and derived from several low earth orbit (LEO, including NASA Terra and Aqua MODIS, NOAA AVHRR) and geosynchronous (GEO, including GOES (east and west), METEOSAT, INSAT-3D, MTSAT-2, and HIMAWARI-8) satellite imagers were collected to create hourly 5-km resolution global composites of data necessary to compute angular distribution models (ADM) for reflected shortwave (SW) and longwave (LW) radiation. The satellite data provide an independent source of radiance measurements and scene identification information necessary to construct ADMs that are used to determine the daytime Earth radiation budget. To optimize spatial matching between EPIC measurements and the high-resolution composite cloud properties, LEO/GEO retrievals within the EPIC fields of view (FOV) are convolved to the EPIC point spread function (PSF) in a similar manner to the Clouds and the Earth's Radiant Energy System (CERES) Single Scanner Footprint TOA/Surface Fluxes and Clouds (SSF) product. Examples of the merged LEO/GEO/EPIC product will be presented, describing the chosen radiance and cloud properties and

  17. Space Gravity Spectroscopy - determination of the Earth's gravitational field by means of Newton interpolated LEO ephemeris Case studies on dynamic (CHAMP Rapid Science Orbit) and kinematic orbits

    NASA Astrophysics Data System (ADS)

    Reubelt, T.; Austen, G.; Grafarend, E. W.

    2003-07-01

    An algorithm for the (kinematic) orbit analysis of a Low Earth Orbiting (LEO) GPS tracked satellite to determine the spherical harmonic coefficients of the terrestrial gravitational field is presented. A contribution to existing long wavelength gravity field models is expected since the kinematic orbit of a LEO satellite can nowadays be determined with very high accuracy in the range of a few centimeters. To demonstrate the applicability of the proposed method, first results from the analysis of real CHAMP Rapid Science (dynamic) Orbits (RSO) and kinematic orbits are illustrated. In particular, we take advantage of Newton's Law of Motion which balances the acceleration vector and the gradient of the gravitational potential with respect to an Inertial Frame of Reference (IRF). The satellite's acceleration vector is determined by means of the second order functional of Newton's Interpolation Formula from relative satellite ephemeris (baselines) with respect to the IRF. Therefore the satellite ephemeris, which are normally given in a Body fixed Frame of Reference (BRF) have to be transformed into the IRF. Subsequently the Newton interpolated accelerations have to be reduced for disturbing gravitational and non-gravitational accelerations in order to obtain the accelerations caused by the Earth's gravitational field. For a first insight in real data processing these reductions have been neglected. The gradient of the gravitational potential, conventionally expressed in vector-valued spherical harmonics and given in a Body Fixed Frame of Reference, must be transformed from BRF to IRF by means of the polar motion matrix, the precession-nutation matrices and the Greenwich Siderial Time Angle (GAST). The resulting linear system of equations is solved by means of a least squares adjustment in terms of a Gauss-Markov model in order to estimate the spherical harmonics coefficients of the Earth's gravitational field.Key words. space gravity spectroscopy, spherical harmonics

  18. Analyzing the interstellar neutral He bulk flow parameters with IBEX-Lo

    NASA Astrophysics Data System (ADS)

    Leonard, Trevor W.

    2016-08-01

    Our Sun is immersed in a local galactic environment which is composed of a warm, dilute, and partially ionized gas. Due to the Sun's motion relative to this environment, the interstellar neutral (ISN) gas flows through the heliosphere providing the opportunity to perform in-situ observations of the ISN gas from Earth's orbit. The Interstellar Boundary Explorer (IBEX) has observed the ISN gas flow over the past 7 years from a highly elliptical orbit around the Earth. The first observations of ISN H, O, and Ne were recorded by IBEX, along with the most detailed observation of ISN He. Since He is minimally influenced by ionization and charge exchange, the ISN He flow provides a sample of the pristine interstellar environment. Surprisingly, the analysis of the early IBEX observations of the ISN He flow in 2009 and 2010 with two separate analysis techniques indicated a somewhat different ISN He parameter set than the previous neutral gas observations with Ulysses GAS. One analysis technique employs the Warsaw Test Particle Model (WTPM) to simulate the ISN atom trajectories numerically from the observer position to the boundary of the heliosphere at 150 AU with spatial and temporal dependent ionization rates. A computational intensive global chi-squared minimization of the WTPM to IBEX-Lo observations is performed to characterize the ISN He flow. The second analysis technique, and the subject of this study, takes advantage of simplifications possible due to the IBEX viewing geometry of ISN atoms close to perihelion in their hyperbolic trajectories. The analytical model is based on Liouville's Theorem with the assumption that the ISN He distribution is a drifting Maxwellian in the local interstellar medium. The analytical model is used to make a 3-step approach to determining the ISN He flow vector and temperature, rather than a global chi-squared minimization. The first step determines the location of the peak ISN He flux at Earth orbit to fix the relationship between

  19. A study of the coupling between LO phonons and plasmons in InP p-i-n diodes

    NASA Astrophysics Data System (ADS)

    Thao, Dinh Nhu

    2017-03-01

    This paper reports a study investigating the coupling between longitudinal optical (LO) phonons and plasmons in InP p-i-n diodes by a numerical simulation. A significant change is observed in the Fourier transform spectra of transient electric field when taking the coupling into account. The findings show two separate peaks instead of a single plasma peak as for non-coupling case. In addition, the bulk-like dispersion relations of the frequencies of those two peaks on the carrier density are found. Therefore, it is proposed that those behaviors manifest the LO phonon-plasmon coupling in the diodes. Also, there is evidence of the peak clipping by the diode itself, a phenomenon not being seen in the bulk InP semiconductor.

  20. 445 N (100-lbf) LO 2/LCH 4 reaction control engine technology development for future space vehicles

    NASA Astrophysics Data System (ADS)

    Robinson, Philip J.; Veith, Eric M.; Hurlbert, Eric A.; Jimenez, Rafael; Smith, Timothy D.

    2010-03-01

    The National Aeronautics and Space Administration (NASA) have identified liquid oxygen (LO2)/liquid methane (LCH4) propulsion systems as promising options for some future space vehicles. NASA issued a contract to Aerojet to develop a 445 N (100-lbf) LO 2/LCH 4 Reaction Control Engine (RCE) aimed at reducing the risk of utilizing a cryogenic reaction control system (RCS) on a space vehicle. Aerojet utilized innovative design solutions to develop an RCE that can ignite reliably over a broad range of inlet temperatures, perform short minimum impulse bits (MIB) at small electrical pulse widths (EPW), and produce excellent specific impulse (Isp) across a range of engine mixture ratios (MR). These design innovations also provide a start transient with a benign mixture ratio (MR), ensuring good thrust chamber compatibility and long life. In addition, this RCE can successfully operate at MRs associated with main engines, enabling the RCE to provide emergency backup propulsion to minimize vehicle propellant load and overall system mass.

  1. 100-Lb(f) LO2/LCH4 Reaction Control Engine Technology Development for Future Space Vehicles

    NASA Technical Reports Server (NTRS)

    Robinson, Philip J.; Veith, Eric M.; Hurlbert, Eric A.; Jimenez, Rafael; Smith, Timothy D.

    2008-01-01

    The National Aeronautics and Space Administration (NASA) has identified liquid oxygen (LO2)/liquid methane (LCH4) propulsion systems as promising options for some future space vehicles. NASA issued a contract to Aerojet to develop a 100-lbf (445 N) LO2/LCH4 Reaction Control Engine (RCE) aimed at reducing the risk of utilizing a cryogenic reaction control system (RCS) on a space vehicle. Aerojet utilized innovative design solutions to develop an RCE that can ignite reliably over a broad range of inlet temperatures, perform short minimum impulse bits (MIB) at small electrical pulse widths (EPW), and produce excellent specific impulse (Isp) across a range of engine mixture ratios (MR). These design innovations also provide a start transient with a benign MR, ensuring good thrust chamber compatibility and long life. In addition, this RCE can successfully operate at MRs associated with main engines, enabling the RCE to provide emergency backup propulsion to minimize vehicle propellant load and overall system mass.

  2. Temperature dependence of the A1(LO) and E2 (high) phonons in hexagonal InN nanowires

    NASA Astrophysics Data System (ADS)

    Song, B.; Jian, J. K.; Wang, G.; Bao, H. Q.; Chen, X. L.

    2007-06-01

    The frequencies and dampings of the zone-center optical phonon modes of A1(LO) (longitudinal-optical) and E2 (high) in wurtzite InN nanowires have been investigated by micro-Raman scattering in the temperature range from 80 to 300 K. Our results reveal that the phonon frequencies decrease and the linewidths broaden with increasing temperature. The obtained experimental data of the frequencies and linewidths at various temperatures can be well described by an empirical model which takes into account the contribution of the thermal expansion of lattice and symmetric decay of phonons into two and three identical phonons with lower energy. The results show that decay into two phonons is the probable channel for the A1(LO) mode and three-phonon decay dominates the E2 (high) mode.

  3. LoTo: a graphlet based method for the comparison of local topology between gene regulatory networks

    PubMed Central

    Contreras-Riquelme, Sebastián; Dominguez, Calixto; Perez-Acle, Tomas

    2017-01-01

    One of the main challenges of the post-genomic era is the understanding of how gene expression is controlled. Changes in gene expression lay behind diverse biological phenomena such as development, disease and the adaptation to different environmental conditions. Despite the availability of well-established methods to identify these changes, tools to discern how gene regulation is orchestrated are still required. The regulation of gene expression is usually depicted as a Gene Regulatory Network (GRN) where changes in the network structure (i.e., network topology) represent adjustments of gene regulation. Like other networks, GRNs are composed of basic building blocks; small induced subgraphs called graphlets. Here we present LoTo, a novel method that using Graphlet Based Metrics (GBMs) identifies topological variations between different states of a GRN. Under our approach, different states of a GRN are analyzed to determine the types of graphlet formed by all triplets of nodes in the network. Subsequently, graphlets occurring in a state of the network are compared to those formed by the same three nodes in another version of the network. Once the comparisons are performed, LoTo applies metrics from binary classification problems calculated on the existence and absence of graphlets to assess the topological similarity between both network states. Experiments performed on randomized networks demonstrate that GBMs are more sensitive to topological variation than the same metrics calculated on single edges. Additional comparisons with other common metrics demonstrate that our GBMs are capable to identify nodes whose local topology changes between different states of the network. Notably, due to the explicit use of graphlets, LoTo captures topological variations that are disregarded by other approaches. LoTo is freely available as an online web server at http://dlab.cl/loto. PMID:28265516

  4. LoTo: a graphlet based method for the comparison of local topology between gene regulatory networks.

    PubMed

    Martin, Alberto J; Contreras-Riquelme, Sebastián; Dominguez, Calixto; Perez-Acle, Tomas

    2017-01-01

    One of the main challenges of the post-genomic era is the understanding of how gene expression is controlled. Changes in gene expression lay behind diverse biological phenomena such as development, disease and the adaptation to different environmental conditions. Despite the availability of well-established methods to identify these changes, tools to discern how gene regulation is orchestrated are still required. The regulation of gene expression is usually depicted as a Gene Regulatory Network (GRN) where changes in the network structure (i.e., network topology) represent adjustments of gene regulation. Like other networks, GRNs are composed of basic building blocks; small induced subgraphs called graphlets. Here we present LoTo, a novel method that using Graphlet Based Metrics (GBMs) identifies topological variations between different states of a GRN. Under our approach, different states of a GRN are analyzed to determine the types of graphlet formed by all triplets of nodes in the network. Subsequently, graphlets occurring in a state of the network are compared to those formed by the same three nodes in another version of the network. Once the comparisons are performed, LoTo applies metrics from binary classification problems calculated on the existence and absence of graphlets to assess the topological similarity between both network states. Experiments performed on randomized networks demonstrate that GBMs are more sensitive to topological variation than the same metrics calculated on single edges. Additional comparisons with other common metrics demonstrate that our GBMs are capable to identify nodes whose local topology changes between different states of the network. Notably, due to the explicit use of graphlets, LoTo captures topological variations that are disregarded by other approaches. LoTo is freely available as an online web server at http://dlab.cl/loto.

  5. Design, Calibration, and Expected On-Orbit Performance of the GOES-R MPS-LO Suprathermal Plasma Analyzer Instrument

    NASA Astrophysics Data System (ADS)

    Golightly, M. J.; McGarity, J. O.; Dichter, B. K.; Galica, G. E.

    2015-12-01

    The next generation U.S. geosynchronous weather satellite—GOES series R-U—will include for the first time a suprathermal plasma analyzer. The Magnetospheric Particle Sensor-Low (MPS-LO), an electrostatic analyzer utilizing triquadrispheric geometry (270° turn)deflection electrodes, will measure the flux of electrons and ions with energies between 30 eV - 30 keV in fifteen logarithmically-spaced differential energy channels and arrival direction in twelve angular bins. MPS-LO consists of two sensor heads mounted in a common electronics box. Each sensor head contains a set of deflection electrodes, microchannel plates, and segmented detector anodes. The common electronics box provides the power and I/O interface with a data processing unit, voltage supplies for all of the instrument's electronics, high voltage for the deflection electrodes, in-flight calibration pulsers, and the digital electronics to process signals from sensor heads' detector anodes. Great care was taken in the manufacture and mounting of the triquadrisphere deflection electrodes; each electrode was machined from a single piece of aluminum and specific electrode combinations were mounted with precision machined spacers and matched drilling. The precise fabrication and assembly resulted in near perfect spherical electric fields between the electrodes. The triquadrispheric electrode shape also prevents photons from reaching the detection elements-as a result, MPS-LO is solar blind. The combined field-of-view for the two sensor heads is 180° x 5°, with the larger angle in a plane perpendicular to the spacecraft's orbit and its central axis oriented anti-Earthward. An incident particle's arrival direction is determined in one of twelve 15° x 5° angular zones. A set of shielded anodes is used to measure the background caused by penetrating charged particles that reach the MCPs; this background data is used to correct the MPS-LO data. The instrument's energy resolution ΔE/E is 5.8%.

  6. The Physical Constraints on a New LoBAL QSO at z = 4.82

    NASA Astrophysics Data System (ADS)

    Yi, Weimin; Green, Richard; Bai, Jin-Ming; Wang, Tinggui; Grier, Catherine J.; Trump, Jonathan R.; Brandt, William N.; Zuo, Wenwen; Yang, Jinyi; Wang, Feige; Yang, Chenwei; Wu, Xue-Bing; Zhou, Hongyan; Fan, Xiaohui; Jiang, Linhua; Yang, Qian; Varricatt, Watson; Kerr, Tom; Milne, Peter; Benigni, Sam; Wang, Jian-Guo; Zhang, Jujia; Wang, Fang; Wang, Chuan-Jun; Xin, Yu-Xin; Fan, Yu-Feng; Chang, Liang; Zhang, Xiliang; Lun, Bao-Li

    2017-04-01

    Very few low-ionization broad absorption line (LoBAL) QSOs have been found at high redshifts, to date. One high-redshift LoBAL QSO, J0122+1216, was recently discovered by the Lijiang 2.4 m Telescope, with an initial redshift determination of 4.76. Aiming to investigate its physical properties, we carried out follow-up observations in the optical and near-IR spectroscopy. Near-IR spectra from UKIRT and P200 confirm that it is a LoBAL, with a new redshift determination of 4.82 ± 0.01 based on the Mg ii emission-line. The new Mg ii redshift determination reveals strong blueshifts and asymmetry of the high-ionization emission lines. We estimate a black hole mass of ∼2.3 × 109 M ⊙ and Eddington ratio of ∼1.0 according to the empirical Mg ii-based single-epoch relation and bolometric correction factor. It is possible that strong outflows are the result of an extreme quasar environment driven by the high Eddington ratio. A lower limit on the outflowing kinetic power (>0.9% L Edd) is derived from both emission and absorption lines, indicating that these outflows play a significant role in the feedback process that regulates the growth of its black hole, as well as host galaxy evolution.

  7. Lava bubble-wall fragments formed by submarine hydrovolcanic explosions on Lo'ihi Seamount and Kilauea Volcano

    USGS Publications Warehouse

    Clague, D.A.; Davis, A.S.; Bischoff, J.L.; Dixon, J.E.; Geyer, R.

    2000-01-01

    Glassy bubble-wall fragments, morphologically similar to littoral limu o Pele, have been found in volcanic sands erupted on Lo'ihi Seamount and along the submarine east rift zone of Kilauea Volcano. The limu o Pele fragments are undegassed with respect to H2O and S and formed by mild steam explosions. Angular glass sand fragments apparently form at similar, and greater, depths by cooling-contraction granulation. The limu o Pele fragments from Lo'ihi Seamount are dominantly tholeiitic basalt containing 6.25-7.25% MgO. None of the limu o Pele samples from Lo'ihi Seamount contains less than 5.57% MgO, suggesting that higher viscosity magmas do not form lava bubbles. The dissolved CO2 and H2O contents of 7 of the limu o Pele fragments indicate eruption at 1200??300 m depth (120??30 bar). These pressures exceed that generally thought to limit steam explosions. We conclude that hydrovolcanic eruptions are possible, with appropriate pre-mixing conditions, at pressures as great as 120 bar.

  8. Comments on Virginia LoCastro's "Learning Strategies and Learning Environments." Making Sense of Learning Strategy Assessment: Toward a Higher Standard of Research Accuracy.

    ERIC Educational Resources Information Center

    Oxford, Rebecca L.; Green, John M.

    1995-01-01

    Critiques an article by Virginia LoCastro that contrasted quantitative data (using the Strategy Inventory for Language Learning, or SILL) and qualitative data (using group interviews) and finds the conclusions drawn from the comparison unjustified on various grounds. A reply by LoCastro is included. (Contains a combined total of 20 references.)…

  9. Operational specification and forecasting advances for Dst, LEO thermospheric densities, and aviation radiation dose and dose rate

    NASA Astrophysics Data System (ADS)

    Tobiska, W.; Knipp, D. J.; Burke, W. J.; Bouwer, D.; Bailey, J. J.; Hagan, M. P.; Didkovsky, L. V.; Garrett, H. B.; Bowman, B. R.; Gannon, J. L.; Atwell, W.; Blake, J. B.; Crain, W.; Rice, D.; Schunk, R. W.; Fulgham, J.; Bell, D.; Gersey, B.; Wilkins, R.; Fuschino, R.; Flynn, C.; Cecil, K.; Mertens, C. J.; Xu, X.; Crowley, G.; Reynolds, A.; Azeem, S. I.; Wiley, S.; Holland, M.; Malone, K.

    2013-12-01

    Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the space environment domains that are affected by space weather, the magnetosphere, thermosphere, and even troposphere are key regions that are affected. Space Environment Technologies (SET) has developed and is producing innovative space weather applications. Key operational systems for providing timely information about the effects of space weather on these domains are SET's Magnetosphere Alert and Prediction System (MAPS), LEO Alert and Prediction System (LAPS), and Automated Radiation Measurements for Aviation Safety (ARMAS) system. MAPS provides a forecast Dst index out to 6 days through the data-driven, redundant data stream Anemomilos algorithm. Anemomilos uses observational proxies for the magnitude, location, and velocity of solar ejecta events. This forecast index is used by satellite operations to characterize upcoming geomagnetic storms, for example. LAPS is the SET fully redundant operational system providing recent history, current epoch, and forecast solar and geomagnetic indices for use in operational versions of the JB2008 thermospheric density model. The thermospheric densities produced by that system, driven by the LAPS data, are forecast to 72-hours to provide the global mass densities for satellite operators. ARMAS is a project that has successfully demonstrated the operation of a micro dosimeter on aircraft to capture the real-time radiation environment due to Galactic Cosmic Rays and Solar Energetic Particles. The dose and dose-rates are captured on aircraft, downlinked in real-time via the Iridium satellites, processed on the ground, incorporated into the most recent NAIRAS global radiation climatology data runs, and made available to end users via the web and smart phone apps. ARMAS provides the 'weather' of the radiation environment to improve air-crew and passenger safety

  10. Operational specification and forecasting advances for Dst, LEO thermospheric densities, and aviation radiation dose and dose rate

    NASA Astrophysics Data System (ADS)

    Tobiska, W. Kent

    Space weather’s effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun’s photons, particles, and fields. Of the space environment domains that are affected by space weather, the magnetosphere, thermosphere, and even troposphere are key regions that are affected. Space Environment Technologies (SET) has developed and is producing innovative space weather applications. Key operational systems for providing timely information about the effects of space weather on these domains are SET’s Magnetosphere Alert and Prediction System (MAPS), LEO Alert and Prediction System (LAPS), and Automated Radiation Measurements for Aviation Safety (ARMAS) system. MAPS provides a forecast Dst index out to 6 days through the data-driven, redundant data stream Anemomilos algorithm. Anemomilos uses observational proxies for the magnitude, location, and velocity of solar ejecta events. This forecast index is used by satellite operations to characterize upcoming geomagnetic storms, for example. In addition, an ENLIL/Rice Dst prediction out to several days has also been developed and will be described. LAPS is the SET fully redundant operational system providing recent history, current epoch, and forecast solar and geomagnetic indices for use in operational versions of the JB2008 thermospheric density model. The thermospheric densities produced by that system, driven by the LAPS data, are forecast to 72-hours to provide the global mass densities for satellite operators. ARMAS is a project that has successfully demonstrated the operation of a micro dosimeter on aircraft to capture the real-time radiation environment due to Galactic Cosmic Rays and Solar Energetic Particles. The dose and dose-rates are captured on aircraft, downlinked in real-time via the Iridium satellites, processed on the ground, incorporated into the most recent NAIRAS global radiation climatology data runs, and made available to end users via the web and

  11. Production of lion (Panthera leo) blastocysts after in vitro maturation of oocytes and intracytoplasmic sperm injection.

    PubMed

    Fernandez-Gonzalez, Lorena; Hribal, Romy; Stagegaard, Julia; Zahmel, Jennifer; Jewgenow, Katarina

    2015-04-01

    Assisted reproductive techniques are becoming widely applied to the breeding of endangered species, but establishing reliable protocols for the production of embryos in vitro is challenging because of the scarcity of sample material. In our study, we applied an assisted reproductive technique protocol for IVM and intracytoplasmic sperm injection (ICSI), developed in the domestic cat, to oocytes retrieved from ovaries of four 2-year-old lionesses (Panthera leo) eight hours postmortem. In total, 68 cumulus-oocyte complexes of good quality were randomly distributed and cultured for 32 to 34 hours in two different maturation culture media, consisting of Medium 199 with Earle's salts, 3 mg/mL BSA, 0.1 mg/mL cysteine, 1.4 mg/mL sodium pyruvate, 0.6 mg/mL sodium lactate, 0.15 mg/mL l-glutamine, and 0.055 mg/mL gentamicin. Hormonal supplementation of IVM_1 was 0.02 IU/mL FSH and 0.05 IU/mL LH; IVM_2 consisted of 1.64 IU/mL FSH, 1.06 IU/mL LH, and 1 μg/mL 17ß-estradiol. Differences in hormonal supplementation did not produce significant differences in oocyte maturation rates, which were 39.4% in IVM_1 and 34.3% in IVM_2. Matured oocytes were microinjected with homologous frozen-thawed spermatozoa, and subsequent cleavage rates were 30.8% and 58.3%, respectively. Half of the embryos derived from oocytes matured in IVM_1 developed into blastocysts, whereas only 28.6% of embryos from oocytes matured in IVM_2 reached the blastocyst stage. Morula stages were present from Day 6 onward, and blastocyst stages from Day 9 on, indicating a slower developmental speed in comparison with domestic cats. This is the first report of in vitro-produced blastocysts using ICSI in the lion, and the results report that IVM and ICSI can be successfully performed with cumulus-oocyte complexes retrieved from ovaries after eight hours of shipping, obtaining competent embryos in culture.

  12. Characteristics of Offshore Hawai';i Island Seismicity and Velocity Structure, including Lo';ihi Submarine Volcano

    NASA Astrophysics Data System (ADS)

    Merz, D. K.; Caplan-Auerbach, J.; Thurber, C. H.

    2013-12-01

    The Island of Hawai';i is home to the most active volcanoes in the Hawaiian Islands. The island's isolated nature, combined with the lack of permanent offshore seismometers, creates difficulties in recording small magnitude earthquakes with accuracy. This background offshore seismicity is crucial in understanding the structure of the lithosphere around the island chain, the stresses on the lithosphere generated by the weight of the islands, and how the volcanoes interact with each other offshore. This study uses the data collected from a 9-month deployment of a temporary ocean bottom seismometer (OBS) network fully surrounding Lo';ihi volcano. This allowed us to widen the aperture of earthquake detection around the Big Island, lower the magnitude detection threshold, and better constrain the hypocentral depths of offshore seismicity that occurs between the OBS network and the Hawaii Volcano Observatory's land based network. Although this study occurred during a time of volcanic quiescence for Lo';ihi, it establishes a basis for background seismicity of the volcano. More than 480 earthquakes were located using the OBS network, incorporating data from the HVO network where possible. Here we present relocated hypocenters using the double-difference earthquake location algorithm HypoDD (Waldhauser & Ellsworth, 2000), as well as tomographic images for a 30 km square area around the summit of Lo';ihi. Illuminated by using the double-difference earthquake location algorithm HypoDD (Waldhauser & Ellsworth, 2000), offshore seismicity during this study is punctuated by events locating in the mantle fault zone 30-50km deep. These events reflect rupture on preexisting faults in the lower lithosphere caused by stresses induced by volcano loading and flexure of the Pacific Plate (Wolfe et al., 2004; Pritchard et al., 2007). Tomography was performed using the double-difference seismic tomography method TomoDD (Zhang & Thurber, 2003) and showed overall velocities to be slower than

  13. The origins of metamodality in visual object area LO: Bodily topographical biases and increased functional connectivity to S1

    PubMed Central

    Tal, Zohar; Geva, Ran; Amedi, Amir

    2016-01-01

    Recent evidence from blind participants suggests that visual areas are task-oriented and sensory modality input independent rather than sensory-specific to vision. Specifically, visual areas are thought to retain their functional selectivity when using non-visual inputs (touch or sound) even without having any visual experience. However, this theory is still controversial since it is not clear whether this also characterizes the sighted brain, and whether the reported results in the sighted reflect basic fundamental a-modal processes or are an epiphenomenon to a large extent. In the current study, we addressed these questions using a series of fMRI experiments aimed to explore visual cortex responses to passive touch on various body parts and the coupling between the parietal and visual cortices as manifested by functional connectivity. We show that passive touch robustly activated the object selective parts of the lateral–occipital (LO) cortex while deactivating almost all other occipital–retinotopic-areas. Furthermore, passive touch responses in the visual cortex were specific to hand and upper trunk stimulations. Psychophysiological interaction (PPI) analysis suggests that LO is functionally connected to the hand area in the primary somatosensory homunculus (S1), during hand and shoulder stimulations but not to any of the other body parts. We suggest that LO is a fundamental hub that serves as a node between visual-object selective areas and S1 hand representation, probably due to the critical evolutionary role of touch in object recognition and manipulation. These results might also point to a more general principle suggesting that recruitment or deactivation of the visual cortex by other sensory input depends on the ecological relevance of the information conveyed by this input to the task/computations carried out by each area or network. This is likely to rely on the unique and differential pattern of connectivity for each visual area with the rest of the

  14. Hydrogeology and analysis of ground-water withdrawal in the Mendenhall-D'Lo area, Simpson County, Mississippi

    USGS Publications Warehouse

    Strom, E.W.; Oakley, W.T.

    1995-01-01

    The cities of Mendenhall and D'Lo, located in Simpson County, rely on ground water for their public supply and industrial needs. Most of the ground water comes from an aquifer of Miocene age. A study began in 1991 to describe the hydrogeology, analyze effects of ground-water withdrawal by making a drawdown map, and estimate the effects increased ground-water withdrawal might have on water levels in the Miocene age aquifer in the Mendenhall-D'Lo area. The most significant withdrawals of ground water in the study area are from 10 wells screened in the lower sand of the Catahoula Formation of Miocene age. Analysis of the effect of withdrawals from the 10 wells was made using the Theis non- equilibrium equation and applying the principle of superposition. Analysis of 1994 conditions was based on the pumpage history and aquifer properties deter- mined for each well. The drawdown surface resulting from the analysis indicates three general cones of depression. One cone is in the northwestern D'Lo area, one in the south-central Mendenhall area, and one about 1-1/2 miles east of Mendenhall. Calculated drawdown ranges from 21 to 47 feet. Potential drawdown-surface maps were made for 10 years and 20 years beyond 1994 using a constant pumpage. The map made for 10 years beyond 1994 indicates an average total increase in drawdown of about 5.3 feet. The map made for 20 years beyond 1994 indicates an average total increase in drawdown of about 7.3 feet.

  15. Interstellar Hydrogen Fluxes Measured by IBEX-Lo in 2009: Numerical Modeling and Comparison with the Data

    NASA Astrophysics Data System (ADS)

    Katushkina, O. A.; Izmodenov, V. V.; Alexashov, D. B.; Schwadron, N. A.; McComas, D. J.

    2015-10-01

    In this paper, we perform numerical modeling of the interstellar hydrogen fluxes measured by IBEX-Lo during orbit 23 (spring 2009) using a state-of-the-art kinetic model of the interstellar neutral hydrogen distribution in the heliosphere. This model takes into account the temporal and heliolatitudinal variations of the solar parameters as well as the non-Maxwellian kinetic properties of the hydrogen distribution due to charge exchange in the heliospheric interface. We found that there is a qualitative difference between the IBEX-Lo data and the modeling results obtained with the three-dimensional, time-dependent model. Namely, the model predicts a larger count rate in energy bin 2 (20-41 eV) than in energy bin 1 (11-21 eV), while the data shows the opposite case. We perform study of the model parameter effects on the IBEX-Lo fluxes and the ratio of fluxes in two energy channels. We show that the most important parameter, which has a major influence on the ratio of the fluxes in the two energy bins, is the solar radiation pressure. The parameter fitting procedure shows that the best agreement between the model result and the data occurs when the ratio of the solar radiation pressure to the solar gravitation, μ0, is {1.26}-0.076+0.06, and the total ionization rate of hydrogen at 1 AU is {β }E,0={3.7}-0.35+0.39× {10}-7 s-1. We have found that the value of μ0 is much larger than μ0 = 0.89, which is the value derived from the integrated solar Lyα flux data for the period of time studied. We discuss possible reasons for the differences.

  16. Investigation of lightweight designs and materials for LO2 and LH2 propellant tanks for space vehicles, phase 1

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Design, analysis, and fabrication studies were performed on nonintegral (suspended) tanks using a representative space tug design. The LH2 and LO2 tank concept selection was developed. Tank geometries and support relationships were investigated using tug design propellant inertias and ullage pressures, then compared based on total tug systems effects. The tank combinations which resulted in the maximum payload were selected. Tests were conducted on samples of membrane material which was processed in a manner simulating production tank fabrication operations to determine fabrication effects on the fracture toughness of the tank material. Fracture mechanics analyses were also performed to establish a preliminary set of allowables for initial defects.

  17. LO-CO-GRAF (Low Cost Graphics): Generating Maps to Support Command and Control/Crisis Management Using Small Computers.

    DTIC Science & Technology

    1988-03-01

    RF 40 3- ET HR%AT -ONLO*A FSA AD-" IIIEI NIH16 % % % - ,NI ILE 0 NAVAL POSTGRADUATE SCHOOL Monterey, California DTlO $ ELECTE JN161988 ekD D THESIS LO... Thesis Advisor Joseph S. Stewart, II A.. *Approved for public release; distribution is unlimited. ,-I ’ S _--- . .. .. , . -, ., ,. .. ., 5.,. . *5*5...Time Covered 14 Date of Report (year, month, day) 15 Page Count Master’s Thesis From To March 1988 157 16 Supplementary Notation The views expressed in

  18. Optical and X-ray studies of chromospherically active stars: FR Cancri, HD 95559 and LO Pegasi

    NASA Technical Reports Server (NTRS)

    Pandey, J. C.; Singh, K. P.; Drake, S. A.; Sagar, R.

    2005-01-01

    We present a multiwavelength study of three chromospherically active stars, namely FR Cnc (= BD +16 degrees 1753), HD 95559 and LO Peg (=BD +22 degrees 4409), including newly obtained optical photometry, (for FR Cnc) low-resolution optical spectroscopy, as well as archival IR and X-ray observations. The BVR photometry carried out during the years 2001 - 2004 has found significant photometric variability to be present in all three stars. For FR Cnc, a photometric period 0.826685 +/- 0.000034 d has been established. The strong variation in the phase and amplitude of the FR Cnc light curves when folded on this period implies the presence of evolving and migrating spots or spot groups on its surface. Two independent spots with migration periods of 0.97 and 0.93 years respectively are inferred. The photometry of HD 95559 suggests the formation of a spot (group) during the interval of our observations. We infer the existence of two independent spots or groups in the photosphere of LO Peg, one of which has a migration period of 1.12 years. The optical spectroscopy of FR Cnc carried out during 2002-2003, reveals the presence of strong and variable Ca I1 H and K, H(sub beta) and H(sub alpha) emission features indicative of high level of chromospheric activity. The value of 5.3 for the ratio of the excess emission in H(sub alpha) to H(sub beta), EH(sub alpha)/EH(sub beta), suggests that the chromospheric emission may arise from an extended off-limb region. We have searched for the presence of color excesses in the near-IR JHK bands of these stars using 2MASS data, but none of them appear to have any significant color excess. We have also analyzed archival X-ray observations of HD 95559 and LO Peg carried out by with the ROSAT observatory. The best fit models to their X-ray spectra imply the presence of two coronal plasma components of differing temperatures and with sub-solar metal abundances. The inferred emission measures and temperatures of these systems are similar to

  19. Design of combinatorial libraries for the exploration of virtual hits from fragment space searches with LoFT.

    PubMed

    Lessel, Uta; Wellenzohn, Bernd; Fischer, J Robert; Rarey, Matthias

    2012-02-27

    A case study is presented illustrating the design of a focused CDK2 library. The scaffold of the library was detected by a feature trees search in a fragment space based on reactions from combinatorial chemistry. For the design the software LoFT (Library optimizer using Feature Trees) was used. The special feature called FTMatch was applied to restrict the parts of the queries where the reagents are permitted to match. This way a 3D scoring function could be simulated. Results were compared with alternative designs by GOLD docking and ROCS 3D alignments.

  20. Seasonality and paleoecology of the late Cretaceous multi-taxa vertebrate assemblage of "Lo Hueco" (central eastern Spain).

    PubMed

    Domingo, Laura; Barroso-Barcenilla, Fernando; Cambra-Moo, Oscar

    2015-01-01

    Isotopic studies of multi-taxa terrestrial vertebrate assemblages allow determination of paleoclimatic and paleoecological aspects on account of the different information supplied by each taxon. The late Campanian-early Maastrichtian "Lo Hueco" Fossil-Lagerstätte (central eastern Spain), located at a subtropical paleolatitude of ~31°N, constitutes an ideal setting to carry out this task due to its abundant and diverse vertebrate assemblage. Local δ18OPO4 values estimated from δ18OPO4 values of theropods, sauropods, crocodyliforms, and turtles are close to δ18OH2O values observed at modern subtropical latitudes. Theropod δ18OH2O values are lower than those shown by crocodyliforms and turtles, indicating that terrestrial endothermic taxa record δ18OH2O values throughout the year, whereas semiaquatic ectothermic taxa δ18OH2O values represent local meteoric waters over a shorter time period when conditions are favorable for bioapatite synthesis (warm season). Temperatures calculated by combining theropod, crocodyliform, and turtle δ18OH2O values and gar δ18OPO4 have enabled us to estimate seasonal variability as the difference between mean annual temperature (MAT, yielded by theropods) and temperature of the warmest months (TWMs, provided by crocodyliforms and turtles). ΔTWMs-MAT value does not point to a significantly different seasonal thermal variability when compared to modern coastal subtropical meteorological stations and Late Cretaceous rudists from eastern Tethys. Bioapatite and bulk organic matter δ13C values point to a C3 environment in the "Lo Hueco" area. The estimated fractionation between sauropod enamel and diet is ~15‰. While waiting for paleoecological information yielded by the ongoing morphological study of the "Lo Hueco" crocodyliforms, δ13C and δ18OCO3 results point to incorporation of food items with brackish influence, but preferential ingestion of freshwater. "Lo Hueco" turtles showed the lowest δ13C and δ18OCO3 values of the