WorldWideScience

Sample records for altitude polar orbiting

  1. Investigating the auroral electrojets with low altitude polar orbiting satellites

    DEFF Research Database (Denmark)

    Moretto, T.; Olsen, Nils; Ritter, P.; Lu, G.

    2002-01-01

    Three geomagnetic satellite missions currently provide high precision magnetic field measurements from low altitude polar orbiting spacecraft. We demonstrate how these data can be used to determine the intensity and location of the horizontal currents that flow in the ionosphere, predominantly in...... the auroral electrojets. First, we examine the results during a recent geomagnetic storm. The currents derived from two satellites at different altitudes are in very good agreement, which verifies good stability of the method. Further, a very high degree of correlation (correlation coefficients of 0...

  2. Investigating the auroral electrojets with low altitude polar orbiting satellites

    DEFF Research Database (Denmark)

    Moretto, T.; Olsen, Nils; Ritter, P.;

    2002-01-01

    in the auroral electrojets. First, we examine the results during a recent geomagnetic storm. The currents derived from two satellites at different altitudes are in very good agreement, which verifies good stability of the method. Further, a very high degree of correlation (correlation coefficients of 0...... to another event for which the combined measurements of the three satellites provide a comprehensive view of the current systems. The analysis hereof reveals some surprising results concerning the connection between solar wind driver and the resulting ionospheric currents. Specifically, preconditioning...

  3. Using Polar-orbiting Environmental Satellite data to specify the radiation environment up to 1200 km altitude

    Science.gov (United States)

    O'Brien, T. P.; Mazur, J. E.; Guild, T. B.; Looper, M. D.

    2015-08-01

    Data from the Deal dosimeter payload on the Rapid Pathfinder satellite provide daily maps of the radiation environment on a sphere at 1200 km altitude. Through the use of magnetic coordinates, these dosimeter maps can be projected down to lower altitudes, providing valuable information for satellite anomaly resolution for vehicles in low Earth orbit (LEO). Unfortunately, the Deal data are not widely available, and the mission has a limited lifetime. As an alternative, we present a method to estimate the Deal daily maps using belt index data from NOAA's Polar-orbiting Environmental Satellite (POES) vehicles. The method addresses only trapped radiation but could readily be supplemented with POES's own measurements of solar particle radiation reaching LEO.

  4. Dust observations at orbital altitudes surrounding Mars

    Science.gov (United States)

    Andersson, L.; Weber, T. D.; Malaspina, D.; Crary, F.; Ergun, R. E.; Delory, G. T.; Fowler, C. M.; Morooka, M. W.; McEnulty, T.; Eriksson, A. I.; Andrews, D. J.; Horanyi, M.; Collette, A.; Yelle, R.; Jakosky, B. M.

    2015-11-01

    Dust is common close to the martian surface, but no known process can lift appreciable concentrations of particles to altitudes above ~150 kilometers. We present observations of dust at altitudes ranging from 150 to above 1000 kilometers by the Langmuir Probe and Wave instrument on the Mars Atmosphere and Volatile Evolution spacecraft. Based on its distribution, we interpret this dust to be interplanetary in origin. A comparison with laboratory measurements indicates that the dust grain size ranges from 1 to 12 micrometers, assuming a typical grain velocity of ~18 kilometers per second. These direct observations of dust entering the martian atmosphere improve our understanding of the sources, sinks, and transport of interplanetary dust throughout the inner solar system and the associated impacts on Mars’s atmosphere.

  5. Dust observations at orbital altitudes surrounding Mars.

    Science.gov (United States)

    Andersson, L; Weber, T D; Malaspina, D; Crary, F; Ergun, R E; Delory, G T; Fowler, C M; Morooka, M W; McEnulty, T; Eriksson, A I; Andrews, D J; Horanyi, M; Collette, A; Yelle, R; Jakosky, B M

    2015-11-01

    Dust is common close to the martian surface, but no known process can lift appreciable concentrations of particles to altitudes above ~150 kilometers. We present observations of dust at altitudes ranging from 150 to above 1000 kilometers by the Langmuir Probe and Wave instrument on the Mars Atmosphere and Volatile Evolution spacecraft. Based on its distribution, we interpret this dust to be interplanetary in origin. A comparison with laboratory measurements indicates that the dust grain size ranges from 1 to 12 micrometers, assuming a typical grain velocity of ~18 kilometers per second. These direct observations of dust entering the martian atmosphere improve our understanding of the sources, sinks, and transport of interplanetary dust throughout the inner solar system and the associated impacts on Mars's atmosphere. PMID:26542578

  6. Semianalytic Integration of High-Altitude Orbits under Lunisolar Effects

    Directory of Open Access Journals (Sweden)

    Martin Lara

    2012-01-01

    Full Text Available The long-term effect of lunisolar perturbations on high-altitude orbits is studied after a double averaging procedure that removes both the mean anomaly of the satellite and that of the moon. Lunisolar effects acting on high-altitude orbits are comparable in magnitude to the Earth’s oblateness perturbation. Hence, their accurate modeling does not allow for the usual truncation of the expansion of the third-body disturbing function up to the second degree. Using canonical perturbation theory, the averaging is carried out up to the order where second-order terms in the Earth oblateness coefficient are apparent. This truncation order forces to take into account up to the fifth degree in the expansion of the lunar disturbing function. The small values of the moon’s orbital eccentricity and inclination with respect to the ecliptic allow for some simplification. Nevertheless, as far as the averaging is carried out in closed form of the satellite’s orbit eccentricity, it is not restricted to low-eccentricity orbits.

  7. Observations of polar rain at low and high altitudes

    International Nuclear Information System (INIS)

    Observations in the distant magnetotail lobes (rapprox. >100 R/sub E/)= reveal that electrons in the ∼50- to 1000-eV energy range often exhibit strong, field-aligned bidirectional anisotropies. Because of large tail motions in the variable flow of the solar wind, ISEE 3 data provide extensive sampling of most tail plasma regions in rapid succession. It is found that bidirectional electron fluxes occur predominantly in the lobe connected directly to the sunward interplanetary magnetic field in the open magnetosphere model (north lobe for away sectors and south lobe for toward sectors). Using data from the low-altitude DMSP spacecraft, we compare polar rain electron intensities, energy spectra, and time variations at low altitudes with concurrent bidirectional electron properties measured by ISEE 3. The field-aligned lobe electron phase space densities above ∼200 eV agree well (i.e., to within a factor of ∼2--3) with DMSP-measured polar rain phase space densities near the polar cap. Furthermore, the spectral slopes above 200 eV also are similar at low and high altitudes. Below 100--200 eV there is a thermal electron population in the distant tail, probably arising from local entry of plasma through the distant magnetopause, which is not present at DMSP altitudes. These data suggest that the suprathermal tail lobe electrons are essentially a test particle population which can move freely along field lines to form polar rain; in contrast, the thermal electrons are bound to the tailward flowing lobe ion population far down the tail and thus cannot reach the polar cap regions. copyright American Geophysical Union 1987

  8. Polar Air Quality and Climate from a Molniya Orbit

    Science.gov (United States)

    O'Neill, N.; McConnell, J. C.; Mullins, M.; Chesser, H.; Solheim, B.; Kaminski, J.; Strong, K.; Jones, D.; Drummond, J.; Martin, R.; McElroy, C. T.; Evans, W. F.; Giroux, J. G.; Soucy, M. A.; Buijs, H. L.; Moreau, L. M.; Buttner, G.; Rahnama, P.; Rowlands, N.; Hackett, J.; Bell, A.

    2008-05-01

    The Arctic is a region of rapid climate change with warming temperatures and depleting summer ice which may be exacerbated by transport of soot and other anthropogenic material from mid-latitudes. It is also the source of winter storms delivering cold air to lower latitudes. Currently data is available for these areas from polar orbiting satellites, but only intermittently at a given location as the satellites pass overhead. Data from geostationary satellites, useful at lower latitudes, is not available for the Arctic because viewing angles to high latitude locations from geostationary orbit are poor. We are proposing the use of a satellite in a Molniya orbit for the acquisition of data for high latitudes which is a quasi-stationary orbit close to apogee. This talk will describe a proposal to the Canadian Space Agency for a mission aimed at the acquisition of air quality and climate data in boreal polar regions and mid-latitudes. Molniya orbits (named after the Russian communications satellite series that first used them) are highly elliptical orbits with an inclination of approximately 63°. At this inclination, the Earth oblateness perturbation does not cause any change to the orbit's argument of perigee. Further, if the orbit semi-major axis is chosen appropriately, the orbit can be timed to have a period of half a day (typical Molniya orbits have an apogee altitude of about 39750 km and a perigee altitude of about 600 km). The result of these two constraints is that the satellite is at apogee over the same high latitude location on the Earth every two orbits. At the alternate apogees, it is over a location at the same latitude but 180° away in longitude. Either location provides viewing coverage of the entire Earth above 60°N, and reasonable viewing down to 50°N. Further, because the satellite is travelling slowly at apogee, the viewing geometry is maintained for approximately 2/3 of the orbit (8 hr out of every 12). The suite of instruments we are

  9. A Minimum Delta V Orbit Maintenance Strategy for Low-Altitude Missions Using Burn Parameter Optimization

    Science.gov (United States)

    Brown, Aaron J.

    2011-01-01

    Orbit maintenance is the series of burns performed during a mission to ensure the orbit satisfies mission constraints. Low-altitude missions often require non-trivial orbit maintenance Delta V due to sizable orbital perturbations and minimum altitude thresholds. A strategy is presented for minimizing this Delta V using impulsive burn parameter optimization. An initial estimate for the burn parameters is generated by considering a feasible solution to the orbit maintenance problem. An low-lunar orbit example demonstrates the Delta V savings from the feasible solution to the optimal solution. The strategy s extensibility to more complex missions is discussed, as well as the limitations of its use.

  10. NOAA Polar-orbiting Operational Environmental Satellites (POES) Radiometer Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Polar-orbiting Operational Environmental Satellite (POES) series offers the advantage of daily global coverage, by making nearly polar orbits 14 times per day...

  11. Entanglement of Polarization and Orbital Angular Momentum

    OpenAIRE

    Bhatti, Daniel; von Zanthier, Joachim; Agarwal, Girish S.

    2015-01-01

    We investigate two-photon entangled states using two important degrees of freedom of the electromagnetic field, namely orbital angular momentum (OAM) and spin angular momentum. For photons propagating in the same direction we apply the idea of $\\textit{entanglement duality}$ and develop schemes to do $\\textit{entanglement sorting}$ based either on OAM or polarization. In each case the entanglement is tested using appropriate witnesses. We finally present generalizations of these ideas to thre...

  12. Correlated Observations of Epithermal Neutrons and Polar Illumination for Orbital Neutron Detectors

    Science.gov (United States)

    McClanahan, T. P.; Mitrofanov, I. G.; Boynton, W. V.; Chin, G.; Droege, G.; Evans, L. G.; Garvin, J.; Harshman, K.; Malakhov, A.; Livengood, T.; Milikh, G. M.; Namkung, M.; Nandikotkur, G.; Neumann, G.; Smith, D.; Sagdeev, R.; Sanin, A. G.; Starr, R. D.; Trombka, J. I.

    2012-01-01

    We correlate Lunar Reconnaisance Orbiter's (LRO) Lunar Exploration Neutron Detector (LEND) and the Lunar Prospector Neutron Spectrometer's (LPNS) orbital epithermal neutron maps of the Lunar high-latitudes with co-registered illumination maps derived from the Lunar Orbiter Laser Altimeter (LOLA) topography. Epithermal neutron count rate maps were derived from the LEND: 1) Collimated Sensor for Epithermal Neutrons, CSETNI-4 2) Uncollimated Sensor for Epithermal Neutrons, SETN and the Uncollimated Lunar Prospector: 3) Low-altitude and 4) High-altitude mapping phases. In this abstract we illustrate 1) and 3) and include 2) and 4) in our presentation. The correlative study provides unique perspectives on the regional epithermal neutron fluences from the Lunar polar regions under different detector and altitude configurations.

  13. Analysis on high-altitude earth Orbit Satellite Determination

    Science.gov (United States)

    He, J.; Hou, Y. W.; Yang, L.

    2016-02-01

    The difference is introduced between approx circular apogee orbit and approx circular perigee one by error transmitting at first. Then the characteristic of secant compensation is analysed when radar tracking object with high elevation. And two kinds of orbit force be pressed to, their perturbation influence and their earth-core angles are explained. And then the series of emulation results are shown including error data emulated with Monte Carlo method, the influence of the velocity increment from the ejecting force of spring while satellite-rocket separating and their perturbation influence and the length of influence of the data arc. Then decision analysis of Wald method and Bayesian statistics rule and the results from the two rule are introduced. So the suitable orbit determination decision is put forward from the decision method. Finally the result is tested reasonable and feasible via the real data. In the end it is useful to reference to make orbit decision in short injection of circular orbit far from the earth for calculating concurrently precise and timely.

  14. Exploration for fossil and nuclear fuels from orbital altitudes

    Science.gov (United States)

    Short, N. M.

    1977-01-01

    The paper discusses the application of remotely sensed data from orbital satellites to the exploration for fossil and nuclear fuels. Geological applications of Landsat data are described including map editing, lithologic identification, structural geology, and mineral exploration. Specific results in fuel exploration are reviewed and a series of related Landsat images is included.

  15. China's FY-3 Polar Orbit Meteorological Satellite And Its Applications

    Institute of Scientific and Technical Information of China (English)

    Zhang Jiashen; Fang Meng; Sun Anlai

    2009-01-01

    @@ FY-3 is China's second generation of polar orbit meteorological satellite. FY-3A,the first of the FY-3 series,was launched on May 27,2008 from Taiyuan Satellite Launeh Center. After 5 months of in-orbit test,the satellite and its ground application system were put into trial operation on November 18,2008,marking the successful technical upgrading of China's polar-orbit meteorological satellite.

  16. Plasma density enhancements in the high-altitude polar cap region observed on Akebono

    Science.gov (United States)

    Ichikawa, Yoh-ichi; Abe, Takumi; Yau, Andrew W.

    2002-05-01

    The plasma density in the polar cap ionosphere is generally low (=103 cm-3) above 4000 km altitude, in which the thermal plasma exhibits a distinctively low electron temperature (K) and low parallel ion drift velocity (dusk side. The occurrence of low electron temperature and ion drift velocity appears to suggest the antisunward convection of high-density plasma into the polar cap, and the decrease in electron temperature due to the disruption of field-aligned heat flux in the high-altitude polar cap.

  17. A Minimum (Delta)V Orbit Maintenance Strategy for Low-Altitude Missions Using Burn Parameter Optimization

    Science.gov (United States)

    Brown, Aaron J.

    2011-01-01

    Orbit maintenance is the series of burns performed during a mission to ensure the orbit satisfies mission constraints. Low-altitude missions often require non-trivial orbit maintenance (Delta)V due to sizable orbital perturbations and minimum altitude thresholds. A strategy is presented for minimizing this (Delta)V using impulsive burn parameter optimization. An initial estimate for the burn parameters is generated by considering a feasible solution to the orbit maintenance problem. An example demonstrates the dV savings from the feasible solution to the optimal solution.

  18. Polar-Orbiting Satellite (POES) Images

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Visible and Infrared satellite imagery taken from camera systems or radiometer instruments on satellites in orbit around the poles. Satellite campaigns include...

  19. Orbital angular momentum is dependent on polarization

    OpenAIRE

    Li, Chun-Fang

    2009-01-01

    It is shown that the momentum density of free electromagnetic field splits into two parts. One has no contribution to the net momentum due to the transversality condition. The other yields all the momentum. The angular momentum that originates from the former part is spin, and the angular momentum that originates from the latter part is orbital angular momentum. Expressions for the spin and orbital angular momentum are given in terms of the electric vector in reciprocal space. The spin and or...

  20. Orbital Polarization in Relativistic Density Functional Theory

    OpenAIRE

    Sargolzaei, Mahdi

    2007-01-01

    The description of the magnetic properties of interacting many-particle systems has been one of the most important goals of physics. The problem is to derive the magnetic properties of such systems from quantum mechanical principles. It is well understood that the magnetization in an atom described by quantum numbers, spin (S), orbital (L), and total angular momentum (J) of its electrons. A set of guidelines, known as Hund's rules, discovered by Friedrich Hermann Hunds help us to determine th...

  1. Aeroassisted transfer between coplanar elliptical orbits during near constant altitude coasting

    Science.gov (United States)

    Taratuta, Aba; Mishne, David; Gur, Ilana

    An aeroassisted transfer between coplanar elliptical orbits is presented. The maneuver consists of three thrust impulses and a coast flight in the atmosphere. Several control strategies for the atmospheric coast are analyzed: constant altitude coast, constant velocity glide, constant heating rate coast. For each control strategy, the optimal altitude is chosen. The criterion for the maneuver efficiency was the amount of fuel consumption for a given rotation angle, subject to a heating rate limit. The results are compared with aeroassisted multipass maneuver and aeroassisted drag-only maneuver. It was shown that the coast maneuver extends the region in which the lift-controlled aeroassisted maneuver is superior to other maneuvers. Numerical examples are presented.

  2. Prototype detector development for measurement of high altitude Martian dust using a future orbiter platform

    Science.gov (United States)

    Pabari, Jayesh; Patel, Darshil; Chokhawala, Vimmi; Bogavelly, Anvesh

    2016-07-01

    Dust devils mostly occur during the mid of Southern hemisphere summer on Mars and play a key role in the background dust opacity. Due to continuous bombardment of micrometeorites, secondary ejecta come out from the Moons of the Mars and can easily escape. This phenomenon can contribute dust around the Moons and therefore, also around the Mars. Similar to the Moons of the Earth, the surfaces of the Martian Moons get charged and cause the dust levitation to occur, adding to the possible dust source. Also, interplanetary dust particles may be able to reach the Mars and contribute further. It is hypothesized that the high altitude Martian dust could be in the form of a ring or tori around the Mars. However, no such rings have been detected to the present day. Typically, width and height of the dust torus is ~5 Mars radii wide (~16950 km) in both the planes as reported in the literature. Recently, very high altitude dust at about 1000 km has been found by MAVEN mission and it is expected that the dust may be concentrated at about 150 to 500 km. However, a langmuir probe cannot explain the source of such dust particles. It is a puzzling question to the space scientist how dust has reached to such high altitudes. A dedicated dust instrument on future Mars orbiter may be helpful to address such issues. To study origin, abundance, distribution and seasonal variation of Martian dust, a Mars Orbit Dust Experiment (MODEX) is proposed. In order to measure the Martian dust from a future orbiter, design of a prototype of an impact ionization dust detector has been initiated at PRL. This paper presents developmental aspects of the prototype dust detector and initial results. The further work is underway.

  3. Chorus observations by the Polar spacecraft near the mid-altitude cusp

    Czech Academy of Sciences Publication Activity Database

    Menietti, J. D.; Santolík, Ondřej; Abaci, P. C.

    2009-01-01

    Roč. 57, č. 12 (2009), s. 1412-1418. ISSN 0032-0633 R&D Projects: GA AV ČR IAA301120601 Grant ostatní: NSF(US) ATM-04-43531; NASA(US) NNG05GM52G.; GA MŠk(CZ) ME 842 Institutional research plan: CEZ:AV0Z30420517 Keywords : chorus * mid- altitude cusp * Polar spacecraft Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.067, year: 2009

  4. Controlling the Eccentricity of Polar Lunar Orbits with Low-Thrust Propulsion

    Directory of Open Access Journals (Sweden)

    O. C. Winter

    2009-01-01

    Full Text Available It is well known that lunar satellites in polar orbits suffer a high increase on the eccentricity due to the gravitational perturbation of the Earth. That effect is a natural consequence of the Lidov-Kozai resonance. The final fate of such satellites is the collision with the Moon. Therefore, the control of the orbital eccentricity leads to the control of the satellite's lifetime. In the present work we study this problem and introduce an approach in order to keep the orbital eccentricity of the satellite at low values. The whole work was made considering two systems: the 3-body problem, Moon-Earth-satellite, and the 4-body problem, Moon-Earth-Sun-satellite. First, we simulated the systems considering a satellite with initial eccentricity equals to 0.0001 and a range of initial altitudes between 100 km and 5000 km. In such simulations we followed the evolution of the satellite's eccentricity. We also obtained an empirical expression for the length of time needed to occur the collision with the Moon as a function of the initial altitude. The results found for the 3-body model were not significantly different from those found for the 4-body model. Secondly, using low-thrust propulsion, we introduced a correction of the eccentricity every time it reached the value 0.05. These simulations were made considering a set of different thrust values, from 0.1 N up to 0.4 N which can be obtained by using Hall Plasma Thrusters. In each run we measured the length of time, needed to correct the eccentricity value (from e=0.04 to e=0.05. From these results we obtained empirical expressions of this time as a function of the initial altitude and as a function of the thrust value.

  5. High-resolution Ceres High Altitude Mapping Orbit atlas derived from Dawn Framing Camera images

    Science.gov (United States)

    Roatsch, Th.; Kersten, E.; Matz, K.-D.; Preusker, F.; Scholten, F.; Jaumann, R.; Raymond, C. A.; Russell, C. T.

    2016-09-01

    The Dawn spacecraft Framing Camera (FC) acquired over 2400 clear filter images of Ceres with a resolution of about 140 m/pixel during the six cycles in the High Altitude Mapping Orbit (HAMO) phase between August 18 and October 21, 2015. We ortho-rectified the images from the first cycle and produced a global, high-resolution, controlled photomosaic of Ceres. This global mosaic is the basis for a high-resolution Ceres atlas that consists of 15 tiles mapped at a scale of 1:750,000. The nomenclature used in this atlas was proposed by the Dawn team and was approved by the International Astronomical Union (IAU). The full atlas is available to the public through the Dawn Geographical Information System (GIS) web page

  6. Qualitative features of the evolution of some polar satellite orbits

    Science.gov (United States)

    Vashkov'yak, M. A.

    2016-01-01

    Two special cases of the problem of the secular perturbations in the orbital elements of a satellite with a negligible mass produced by the joint influence of the oblateness of the central planet and the attraction by its most massive (or main) satellites and the Sun are considered. These cases are among the integrable ones in the general nonintegrable evolution problem. The first case is realized when the plane of the satellite orbit and the rotation axis of the planet lie in its orbital plane. The second case is realized when the plane of the satellite orbit is orthogonal to the line of intersection between the equatorial and orbital planes of the planet. The corresponding particular solutions correspond to those polar satellite orbits for which the main qualitative features of the evolution of the eccentricity and pericenter argument are described here. Families of integral curves have been constructed in the phase plane of these elements for the satellite systems of Jupiter, Saturn, and Uranus.

  7. Polarization control of single photon quantum orbital angular momentum states

    OpenAIRE

    Nagali, E.; Sciarrino, F.; De Martini, F.; Piccirillo, B.; Karimi, E.; Marrucci, L.; Santamato, E.

    2009-01-01

    The orbital angular momentum of photons, being defined in an infinitely dimensional discrete Hilbert space, offers a promising resource for high-dimensional quantum information protocols in quantum optics. The biggest obstacle to its wider use is presently represented by the limited set of tools available for its control and manipulation. Here, we introduce and test experimentally a series of simple optical schemes for the coherent transfer of quantum information from the polarization to the ...

  8. Probing Parton Orbital Angular Momentum in Longitudinally Polarized Nucleon

    OpenAIRE

    Ji, Xiangdong; Xiong, Xiaonu; Yuan, Feng

    2012-01-01

    While the total orbital angular momentum (OAM) of a definite quark flavor in a longitudinally-polarized nucleon can be obtained through a sum rule involving twist-two generalized parton distribution (GPDs), its distribution as a function of parton momentum in light-front coordinates is more complicated to define and measure because it involves intrinsically twist-three effects. In this paper, we consider two different parton OAM distributions. The first is manifestly gauge invariant, and its ...

  9. X-ray Orbital Modulations in Intermediate Polars

    CERN Document Server

    Parker, T L; Mukai, K

    2005-01-01

    We present an analysis of 30 archival ASCA and RXTE X-ray observations of 16 intermediate polars to investigate the nature of their orbital modulation. We show that X-ray orbital modulation is widespread amongst these systems, but not ubiquitous as indicated by previous studies that included fewer objects. Only seven of the sixteen systems show a clearly statistically significant modulation depth whose amplitude decreases with increasing X-ray energy. Interpreting this as due to photoelectric absorption in material at the edge of an accretion disc would imply that such modulations are visible for all system inclination angles in excess of 60 degrees. However, it is also apparent that the presence of an X-ray orbital modulation can appear and disappear on a timescale of ~years or months in an individual system. This may be evidence for the presence of a precessing, tilted accretion disc, as inferred in some low mass X-ray binaries.

  10. Spiraling Away from Vesta: Design of the Transfer from the Low to High Altitude Dawn Mapping Orbits

    Science.gov (United States)

    Smith, John C.; Parcher, Daniel W.; Whiffen, Gregory J.

    2013-01-01

    Dawn has successfully completed its orbital mission at Vesta and is currently en route to an orbital rendezvous with Ceres in 2015. The longest duration and most complex portion of the Vesta departure trajectory was the transfer from the low to high altitude science orbit. This paper describes the design of this low-thrust trajectory optimized assuming a minimum-propellant mass objective. The transfer utilized solar-electric ion propulsion applied over 139 spacecraft revolutions about Vesta. Science drivers, operational constraints, and robustness to statistical uncertainties are addressed. The 45-day transfer trajectory was successfully implemented in early 2012.

  11. Orbital polarization and magnetization for independent particles in disordered media

    CERN Document Server

    Schulz-Baldes, Hermann

    2012-01-01

    Formulas for the contribution of the conduction electrons to the polarization and magnetization are derived for disordered systems and within a one-particle framework. These results generalize known formulas for Bloch electrons and the presented proofs considerably simplify and strengthen prior justifications. The new formulas show that orbital polarization and magnetization are of geometric nature. This leads to quantization for a periodically driven Piezo effect as well as the derivative of the magnetization w.r.t. the chemical potential. It is also shown how the latter is connected to boundary currents in Chern insulators. The main technical tools in the proofs are an adaption of Nenciu's super-adiabatic theory to C$^*$-dynamical systems and Bellissard's Ito derivatives w.r.t. the magnetic field.

  12. X-ray spectra and polarization from accreting black holes: polarization from an orbiting spot

    Science.gov (United States)

    Dovčiak, M.; Karas, V.; Matt, G.

    2006-12-01

    The polarization from a spot orbiting around Schwarzschild and extreme Kerr black holes is studied. We assume different models of local polarization. Firstly, as a toy model we set the local polarization vector either normal to the disc plane, or perpendicular to the toroidal magnetic field. Then we examine the more realistic situation with a spot arising due to the emission from the primary source above the disc. We employ either Rayleigh single scattering or Compton multiple scattering approximations. The time dependence of the degree and angle of polarization during the spot revolution is examined as a function of the observer's inclination angle and black hole angular momentum. The gravitational and Doppler shifts, lensing effect as well as time delays are taken into account.

  13. Electrical polarization and orbital magnetization: the modern theories.

    Science.gov (United States)

    Resta, Raffaele

    2010-03-31

    Macroscopic polarization P and magnetization M are the most fundamental concepts in any phenomenological description of condensed media. They are intensive vector quantities that intuitively carry the meaning of dipole per unit volume. But for many years both P and the orbital term in M evaded even a precise microscopic definition, and severely challenged quantum-mechanical calculations. If one reasons in terms of a finite sample, the electric (magnetic) dipole is affected in an extensive way by charges (currents) at the sample boundary, due to the presence of the unbounded position operator in the dipole definitions. Therefore P and the orbital term in M--phenomenologically known as bulk properties--apparently behave as surface properties; only spin magnetization is problemless. The field has undergone a genuine revolution since the early 1990s. Contrary to a widespread incorrect belief, P has nothing to do with the periodic charge distribution of the polarized crystal: the former is essentially a property of the phase of the electronic wavefunction, while the latter is a property of its modulus. Analogously, the orbital term in M has nothing to do with the periodic current distribution in the magnetized crystal. The modern theory of polarization, based on a Berry phase, started in the early 1990s and is now implemented in most first-principle electronic structure codes. The analogous theory for orbital magnetization started in 2005 and is partly work in progress. In the electrical case, calculations have concerned various phenomena (ferroelectricity, piezoelectricity, and lattice dynamics) in several materials, and are in spectacular agreement with experiments; they have provided thorough understanding of the behaviour of ferroelectric and piezoelectric materials. In the magnetic case the very first calculations are appearing at the time of writing (2010). Here I review both theories on a uniform ground in a density functional theory (DFT) framework, pointing out

  14. Polarization radiation of vortex electrons with large orbital angular momentum

    CERN Document Server

    Ivanov, Igor P

    2013-01-01

    Vortex electrons, i.e. freely propagating electrons whose wavefunction has helical wavefronts, could emerge as a novel tool for the physics of electromagnetic (EM) radiation. They carry non-zero intrinsic orbital angular momentum (OAM) $\\ell$ and, for $\\ell \\gg 1$, a large OAM-induced magnetic moment, $\\mu \\approx \\ell \\mu_B$ ($\\mu_B$ is the Bohr magneton), which affects the radiation of EM waves. Here, we consider in detail its influence on two forms of polarization radiation, namely on Cherenkov and transition radiation. Due to large $\\ell$, we can neglect quantum or spin-induced effects, which are of order $\\hbar \\omega/E_e \\ll 1$, but retain the magnetic moment contribution $\\ell \\hbar \\omega/E_e \\lesssim 1$, which makes the quasiclassical approach to polarization radiation applicable. We discuss magnetic moment contribution to polarization radiation, which has never been experimentally observed, and study how its visibility depends on kinematical parameters and permittivity of the medium. In particular, ...

  15. Characterization of cosmic rays and direction dependence in the Polar Region up to 88 km altitude

    Science.gov (United States)

    Zábori, Balázs; Hirn, Attila; Deme, Sándor; Apáthy, István; Pázmándi, Tamás

    2016-02-01

    Aims: The sounding rocket experiment REM-RED was developed to operate on board the REXUS-17 rocket in order to measure the intensity of cosmic rays. The experiment was launched from the ESRANGE Space Center (68 °N, 21 °E) on the 17th of March 2015 at the beginning of the most intense geomagnetic storm within the preceding 10 years. The experiment provided the opportunity to measure the intensity of cosmic rays in the Polar Region up to an altitude of 88 km above sea level. Methods: The experiment employed Geiger-Müller (GM) counters oriented with their axes perpendicular to each other in order to measure the cosmic ray intensity during the flight of the rocket. This measurement setup allowed performing direction-sensitive measurements as well. During the ascent phase the rocket was spinning and hence stabilized along its longitudinal axis looking close to the zenith direction. This phase of the flight was used for studying the direction dependence of the charged particle component of the cosmic rays. Results: In comparison with earlier, similar rocket experiments performed with GM tubes at lower geomagnetic latitudes, significantly higher cosmic radiation flux was measured above 50 km. A non-isotropic behavior was found below 50 km and described in detail for the first time in the Polar Region. This behavior is in good agreement with the results of the TECHDOSE experiment that used the same type of GM tubes on board the BEXUS-14 stratospheric balloon.

  16. Characterization of cosmic rays and direction dependence in the Polar Region up to 88 km altitude

    Directory of Open Access Journals (Sweden)

    Zábori Balázs

    2016-01-01

    Full Text Available Aims: The sounding rocket experiment REM-RED was developed to operate on board the REXUS-17 rocket in order to measure the intensity of cosmic rays. The experiment was launched from the ESRANGE Space Center (68 °N, 21 °E on the 17th of March 2015 at the beginning of the most intense geomagnetic storm within the preceding 10 years. The experiment provided the opportunity to measure the intensity of cosmic rays in the Polar Region up to an altitude of 88 km above sea level. Methods: The experiment employed Geiger-Müller (GM counters oriented with their axes perpendicular to each other in order to measure the cosmic ray intensity during the flight of the rocket. This measurement setup allowed performing direction-sensitive measurements as well. During the ascent phase the rocket was spinning and hence stabilized along its longitudinal axis looking close to the zenith direction. This phase of the flight was used for studying the direction dependence of the charged particle component of the cosmic rays. Results: In comparison with earlier, similar rocket experiments performed with GM tubes at lower geomagnetic latitudes, significantly higher cosmic radiation flux was measured above 50 km. A non-isotropic behavior was found below 50 km and described in detail for the first time in the Polar Region. This behavior is in good agreement with the results of the TECHDOSE experiment that used the same type of GM tubes on board the BEXUS-14 stratospheric balloon.

  17. Orbital mapping of energy bands and the truncated spin polarization in three-dimensional Rashba semiconductors

    CERN Document Server

    Liu, Qihang; Dessau, D S; Zunger, Alex

    2016-01-01

    Associated with spin-orbit coupling (SOC) and inversion symmetry breaking, Rashba spin polarization opens a new avenue for spintronic applications that was previously limited to ordinary magnets. However, spin polarization effects in actual Rashba systems are far more complicated than what conventional single-orbital models would suggest. By studying via first-principles DFT and a multi-orbital k.p model a 3D bulk Rashba system (free of complications by surface effects) we find that the physical origin of the leading spin polarization effects is SOC-induced hybridization between spin and multiple orbitals, especially those with nonzero orbital angular momenta. In this framework we establish a general understanding of the orbital mapping, common to the surface of topological insulators and Rashba system. Consequently, the intrinsic mechanism of various spin polarization effects, which pertain to all Rashba systems even those with global inversion symmetry, is understood as a manifestation of the orbital textur...

  18. The National Polar-orbiting Operational Environmental Satellite System

    Science.gov (United States)

    Hoffman, C. W.; Mango, S.; Schneider, S.; Duda, J.; Haas, J.; Bloom, H.

    2005-12-01

    Over the last decade, the tri-agency Integrated Program Office (IPO), comprised of the National Oceanic and Atmospheric Administration (NOAA), the Department of Defense (DoD), and the National Aeronautics and Space Administration (NASA), has been managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). Once operational later this decade, NPOESS will replace NOAA's Polar-orbiting Operational Environmental Satellites (POES) and DoD's Defense Meteorological Satellite Program (DMSP) systems. The IPO, through its Acquisition and Operations contractor, Northrop Grumman, will launch NPOESS spacecraft into three orbital planes to provide a single, national system capable of satisfying both civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving the existing 'weather' satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - ocean, atmosphere, land, and the space environment. NPOESS will transform today's short-term, space-based ocean research missions into a sustained, operational ocean remote sensing observation program. Ocean measurements comprise one-fourth of the 55 user-validated requirements for geophysical measurements that will be made by NPOESS sensors. In 1997, the IPO initiated a robust sensor risk reduction effort for early development of the critical sensor suites and algorithms necessary to support NPOESS. In 2001, preliminary design efforts were completed for the last of five critical imaging/sounding instruments for NPOESS. Ocean requirements have directly and substantially 'driven' the design of three NPOESS sensors: the Visible/Infrared Imager Radiometer Suite (VIIRS); the Conical-scanning Microwave Imager/Sounder (CMIS); and the Altimeter. With these instruments, NPOESS will deliver higher resolution (spatial and temporal) and more

  19. Localized electron density enhancements in the high-altitude polar ionosphere and their relationships with storm-enhanced density (SED plumes and polar tongues of ionization (TOI

    Directory of Open Access Journals (Sweden)

    Y. Kitanoya

    2011-02-01

    Full Text Available Events of localized electron density increase in the high-altitude (>3000 km polar ionosphere are occasionally identified by the thermal plasma instruments on the Akebono satellite. In this paper, we investigate the vertical density structure in one of such events in detail using simultaneous observations by the Akebono and DMSP F15 satellites, the SuperDARN radars, and a network of ground Global Positioning System (GPS receivers, and the statistical characteristics of a large number (>10 000 of such events using Akebono data over half of an 11-year solar cycle. At Akebono altitude, the parallel drift velocity is remarkably low and the O+ ion composition ratio remarkably high, inside the high plasma-density regions at high altitude. Detailed comparisons between Akebono, DMSP ion velocity and density, and GPS total electron content (TEC data suggest that the localized plasma density increase observed at high altitude on Akebono was likely connected with the polar tongue of ionization (TOI and/or storm enhanced density (SED plume observed in the F-region ionosphere. Together with the SuperDARN plasma convection map these data suggest that the TOI/SED plume penetrated into the polar cap due to anti-sunward convection and the plume existed in the same convection channel as the dense plasma at high altitude; in other words, the two were probably connected to each other by the convecting magnetic field lines. The observed features are consistent with the observed high-density plasma being transported from the mid-latitude ionosphere or plasmasphere and unlikely a part of the polar wind population.

  20. The National Polar-orbiting Operational Environmental Satellite System

    Science.gov (United States)

    Bloom, H.

    The tri-agency Integrated Program Office (IPO) is responsible for managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). NPOESS will replace the current military and civilian operational polar-orbiting ``weather'' satellites. The Northrop Grumman Space Technology - Raytheon team was competitively selected in 2002 as the Acquisition and Operations contractor team to develop, integrate, deploy, and operate NPOESS satellites to meet the tri-agency user requirements for NPOESS over the 10-year (2009-2018) operational life of the program. Beginning in 2009, NPOESS spacecraft will be launched into three orbital planes to provide significantly improved operational capabilities and benefits to satisfy critical civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving operational ``weather'' satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - atmosphere, ocean, land, and the space environment. In recent years, the operational weather forecasting and climate science communities have levied more rigorous requirements on space-based observations of the Earth's system that have significantly increased demands on performance of the instruments, spacecraft, and ground systems required to deliver NPOESS data, products, and information to end users. The ``end-to-end'' system consists of: the spacecraft; instruments and sensors on the spacecraft; launch support capabilities; the command, control, communications, and data routing infrastructure; and data processing hardware and software. NPOESS will observe significantly more phenomena simultaneously from space than its operational predecessors. NPOESS is expected to deliver large volumes of more accurate measurements at higher spatial (horizontal and vertical) and temporal resolution at much higher data

  1. Cryogenic propulsion for the Titan Orbiter Polar Surveyor (TOPS) mission

    Science.gov (United States)

    Mustafi, S.; DeLee, C.; Francis, J.; Li, X.; McGuinness, D.; Nixon, C. A.; Purves, L.; Willis, W.; Riall, S.; Devine, M.; Hedayat, A.

    2016-03-01

    Liquid hydrogen (LH2) and liquid oxygen (LO2) cryogenic propellants can dramatically enhance NASA's ability to explore the solar system due to their superior specific impulse (Isp) capability. Although these cryogenic propellants can be challenging to manage and store, they allow significant mass advantages over traditional hypergolic propulsion systems and are therefore enabling for many planetary science missions. New cryogenic storage techniques such as subcooling and the use of advanced insulation and low thermal conductivity support structures will allow for the long term storage and use of cryogenic propellants for solar system exploration and hence allow NASA to deliver more payloads to targets of interest, launch on smaller and less expensive launch vehicles, or both. These new cryogenic storage technologies were implemented in a design study for the Titan Orbiter Polar Surveyor (TOPS) mission, with LH2 and LO2 as propellants, and the resulting spacecraft design was able to achieve a 43% launch mass reduction over a TOPS mission, that utilized a traditional hypergolic propulsion system with mono-methyl hydrazine (MMH) and nitrogen tetroxide (NTO) propellants. This paper describes the cryogenic propellant storage design for the TOPS mission and demonstrates how these cryogenic propellants are stored passively for a decade-long Titan mission that requires the cryogenics propellants to be stored for 8.5 years.

  2. Polarization and molecular-orbital dependence of strong-field enhanced ionization

    Science.gov (United States)

    Lai, Wei; Guo, Chunlei

    2016-04-01

    In this work we perform a polarization dependence study of enhanced ionization (EI) in diatomic molecules. We find that EI exists when the field polarization is parallel to the molecular axis but disappears when polarization is perpendicular. We further study EI with circular polarization and find that EI exists with circular polarization indicating that rescattering does not play a significant role for EI. Furthermore, we study molecular orbital effect on EI. We find that EI exists in σ type but not π type outmost molecular orbitals.

  3. Localized electron density enhancements in the high-altitude polar ionosphere and their relationships with storm-enhanced density (SED) plumes and polar tongues of ionization (TOI)

    OpenAIRE

    Kitanoya, Y.; Abe, T.; Yau, A.W.; Hori, T; Nishitani, N.

    2011-01-01

    Events of localized electron density increase in the high-altitude (>3000 km) polar ionosphere are occasionally identified by the thermal plasma instruments on the Akebono satellite. In this paper, we investigate the vertical density structure in one of such events in detail using simultaneous observations by the Akebono and DMSP F15 satellites, the SuperDARN radars, and a network of ground Global Positioning System (GPS) receivers, and the statistical characteristics of a large number (&g...

  4. The orbital motion, absolute mass, and high-altitude winds of exoplanet HD209458b

    OpenAIRE

    Snellen, Ignas A. G.; de Kok, Remco J.; de Mooij, Ernst J. W.; Albrecht, Simon

    2010-01-01

    For extrasolar planets discovered using the radial velocity method, the spectral characterization of the host star leads to a mass-estimate of the star and subsequently of the orbiting planet. In contrast, if also the orbital velocity of the planet would be known, the masses of both star and planet could be determined directly using Newton's law of gravity, just as in the case of stellar double-line eclipsing binaries. Here we report on the detection of the orbital velocity of extrasolar plan...

  5. Solar Wind Influence on the Oxygen Content of Ion Outflow in the High Altitude Polar Cap During Solar Minimum Conditions

    Science.gov (United States)

    Elliott, Heather A.; Comfort, Richard H.; Craven, Paul D.; Chandler, Michael O.; Moore, Thomas E.

    2000-01-01

    We correlate solar wind and IMF properties with the properties of O(+) and H(+) in the polar cap in early 1996 during solar minimum conditions at altitudes between 5.5 and 8.9 Re geocentric using the Thermal Ion Dynamics Experiment (TIDE) on the POLAR satellite. Throughout the high altitude polar cap, we observe H(+) to be more abundant than O(+). H(+) is a significant fraction of both the ionosphere and the solar wind, and O(+) is not a significant species in the solar wind. O(+) is the major species in the ionosphere so the faction of O(+) present in the magnetosphere is commonly used as a measure of the ionospheric contribution to the magnetosphere. For these reasons, 0+ is of primary interest in this study. We observe O(+) to be most abundant at lower latitudes when the solar wind speed is low (and low Kp), and at higher solar wind speeds (and high Kp) O(+) is observed across most of the polar cap. We also find that O(+) density and parallel flux are well organized by solar wind dynamic pressure; they both increase with solar wind dynamic pressure. H(+) is not as highly correlated with solar wind and IMF parameters, but H(+) density and parallel flux have some negative correlation with IMF By, and some positive correlation with VswBIMF. In this solar minimum data set, H(+) is dominant so that contributions of this plasma to the plasma sheet would have a very low O(+) to H(+) ratio.

  6. Interrogation of orbital structure by elliptically polarized intense femtosecond laser pulses

    DEFF Research Database (Denmark)

    Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2011-01-01

    We solve the three-dimensional time-dependent Schrödinger equation and present investigations of the imprint of the orbital angular node in photoelectron momentum distributions of an aligned atomic p-type orbital following ionization by an intense elliptically polarized laser pulse of femtosecond...... duration. We investigate the role of light ellipticity and the alignment angle of the major polarization axis of the external field relative to the probed orbital by studying radial and angular momentum distributions, the latter at a fixed narrow interval of final momenta close to the peak of the...... photoelectron momentum distribution. In general only the angular distributions carry a clear signature of the orbital symmetry. Our study shows that circular polarization gives the most clear imprints of orbital nodes. These findings are insensitive to pulse duration....

  7. The orbital period of intermediate polar 1WGA J19582+3232

    CERN Document Server

    Zharikov, S V; Echevarria, J; Cardenas, A A; Zharikov, Sergei. V.; Tovmassian, Gaghik. H.; Echevarria, Juan; Cardenas;, Aixa Aube

    2001-01-01

    The detection of the orbital period of 4.36his reported for the new Intermediate Polar 1 WGA 1958.2+3232. The orbital period was derived from time-resolved photometric and spectral observations. We also confirmed the 733 sec spin period of the White Dwarf consistent with the X-ray pulsations and were able to distinguish the beat period in the light curve. Strong modulations with orbital period are detected in the emission spectral lines from spectral observations. They show the presence of a bright hot spot on the edge of the accretion disk. The parameters of this recently discovered Intermediate Polar are determined.

  8. The conductance and polarization in quantum wires with Rashba and Dresselhaus spin-orbit interactions

    Institute of Scientific and Technical Information of China (English)

    WANG Da-zhi; CHEN Yu-guang

    2008-01-01

    The conductance and polarization are studied in one-dimensional ballistic quantum wire with both Rashba and Dresselhaus spin-orbit interactions.Two kinds of structures are considered in the present work,one with mixture of two interactions and the other with sequence structure of them.We find that the conductance and polarization are strongly affected by these two interactions.With both interactions we obtain a multi-peak contour of spin polarization and a dramatic oscillation pattern of spin conductance,which are due to the different combination of the two spin-orbit interactions.

  9. On the estimation of the equatorial electrojet magnetic signature and peak current density from polar orbiting satellite magnetic measurements

    International Nuclear Information System (INIS)

    Complete text of publication follows. Space-based geomagnetic observations are usually made on board low altitude near polar orbiting satellites. These satellites sweep all longitude sectors and provide quasi regular and homogenous global scale dataset. Especially, for the study of the equatorial electrojet (EEJ) features including its longitude dependence, only satellite magnetic measurements are capable of providing such global coverage. However, the orbit along-track methods of extracting the EEJ signature from satellite observations do not allow an accurate estimate of its peak current density in certain longitude sectors. By comparing ground-based and satellite observations, we show that satellite orbit along-track methods fit well the latitude profiles of the EEJ magnetic effect when the satellite paths are perpendicular to the dip-equator, as in most part of the longitude sectors of Asia and Africa. Otherwise, the EEJ latitude profiles are biased, which leads to poor estimate of the EEJ features (magnetic signature, peak-current density, position of the EEJ center, etc.), as in the Atlantic Ocean and most of South American sectors, where the dip-equator is strongly tilted from the East-West direction.

  10. Wave particle interactions in the high-altitude polar cusp: a Cluster case study

    OpenAIRE

    Grison, B.; Sahraoui, F.; B. Lavraud; T. Chust; N. Cornilleau-Wehrlin; Rème, H.; Balogh, A.; André, M.

    2005-01-01

    On 23 March 2002, the four Cluster spacecraft crossed in close configuration (~100 km separation) the high-altitude (10 RE) cusp region. During a large part of the crossing, the STAFF and EFW instruments have detected strong electromagnetic wave activity at low frequencies, especially when intense field-aligned proton fluxes were detected by the CIS/HIA instrument. In all likelihood, such fluxes correspond to newly-reconnected field lines. A focus on ...

  11. Spin-polarized spin-orbit-split quantum-well states in a metal film

    Energy Technology Data Exchange (ETDEWEB)

    Varykhalov, Andrei; Sanchez-Barriga, Jaime; Gudat, Wolfgang; Eberhardt, Wolfgang; Rader, Oliver [BESSY Berlin (Germany); Shikin, Alexander M. [St. Petersburg State University (Russian Federation)

    2008-07-01

    Elements with high atomic number Z lead to a large spin-orbit coupling. Such materials can be used to create spin-polarized electronic states without the presence of a ferromagnet or an external magnetic field if the solid exhibits an inversion asymmetry. We create large spin-orbit splittings using a tungsten crystal as substrate and break the structural inversion symmetry through deposition of a gold quantum film. Using spin- and angle-resolved photoelectron spectroscopy, it is demonstrated that quantum-well states forming in the gold film are spin-orbit split and spin polarized up to a thickness of at least 10 atomic layers. This is a considerable progress as compared to the current literature which reports spin-orbit split states at metal surfaces which are either pure or covered by at most a monoatomic layer of adsorbates.

  12. Spin-to-orbital angular momentum conversion and spin-polarization filtering in electron beams

    OpenAIRE

    Karimi E.; Marrucci L.; Grillo V.; Santamato E.

    2012-01-01

    We propose the design of a space-variant Wien filter for electron beams that induces a spin half-turn and converts the corresponding spin angular momentum variation into orbital angular momentum of the beam itself by exploiting a geometrical phase arising in the spin manipulation. When applied to a spatially coherent input spin-polarized electron beam, such a device can generate an electron vortex beam, carrying orbital angular momentum. When applied to an unpolarized input beam, the proposed...

  13. Polarized Molecular Orbital Model Chemistry 3. The PMO Method Extended to Organic Chemistry

    OpenAIRE

    Isegawa, Miho; Fiedler, Luke; Leverentz, Hannah R.; Wang, Yingjie; Nachimuthu, Santhanamoorthi; Gao, Jiali; Truhlar, Donald G.

    2013-01-01

    The polarized molecular orbital (PMO) method, a neglect-of-diatomic-differential-overlap (NDDO) semiempirical molecular orbital method previously parameterized for systems composed of O and H, is here extended to carbon. We modified the formalism and optimized all the parameters in the PMO Hamiltonian by using a genetic algorithm and a database containing both electrostatic and energetic properties; the new parameter set is called PMO2. The quality of the resulting predictions is compared to ...

  14. Phase Diagram of Two-dimensional Polarized Fermi Gas With Spin-Orbit Coupling

    OpenAIRE

    Yang, Xiaosen; Wan, Shaolong

    2011-01-01

    We investigate the ground state of the two-dimensional polarized Fermi gas with spin-orbit coupling and construct the phase diagram at zero temperature. We find there exist phase separation when the binding energy is low. As the binding energy increasing, the topological nontrivial superfluid phase coexist with topologically trivial superfluid phase which is topological phase separation. The spin-orbit coupling interaction enhance the triplet pairing and destabilize the phase separation again...

  15. Generation of spin polarization in graphene by the spin-orbit interaction and a magnetic barrier

    Science.gov (United States)

    Zhang, Qingtian; Chan, K. S.; Lin, Zijing

    2014-10-01

    We study the generation of spin polarization in monolayer graphene in the presence of Rashba spin-orbit interaction (SOI) and a ferromagnetic (FM) stripe. It is shown that Rashba SOI alone can generate an in-plane (x-y plane) spin polarization, but a FM stripe with magnetization parallel to the current direction cannot generate any spin polarization. A combination of the Rashba SOI and the magnetic field of a FM stripe can increase the spin polarization to a value close to 100%, and the polarization components can be found along the x, y and z directions. The attainment of highly spin polarized current using the Rashba SOI and FM effect could have useful applications in the development of graphene spintronics.

  16. Generation of spin polarization in graphene by the spin–orbit interaction and a magnetic barrier

    International Nuclear Information System (INIS)

    We study the generation of spin polarization in monolayer graphene in the presence of Rashba spin–orbit interaction (SOI) and a ferromagnetic (FM) stripe. It is shown that Rashba SOI alone can generate an in-plane (x–y plane) spin polarization, but a FM stripe with magnetization parallel to the current direction cannot generate any spin polarization. A combination of the Rashba SOI and the magnetic field of a FM stripe can increase the spin polarization to a value close to 100%, and the polarization components can be found along the x, y and z directions. The attainment of highly spin polarized current using the Rashba SOI and FM effect could have useful applications in the development of graphene spintronics. (paper)

  17. Orbit selection for a Mars geoscience/climatology orbiter

    Science.gov (United States)

    Uphoff, C.

    1984-01-01

    This paper is a presentation of recent work to provide orbit design and selection criteria for a close, nearly polar, nearly circular orbit of Mars. The main aspects of the work are the evaluation of atmospheric drag for altitude selection, the orbit evolution for variations in periapsis altitude, and the interactions of those factors with the science objectives of the MGCO mission. A dynamic model of the Mars atmosphere is available from parallel efforts and the latest estimates of the upper atmospheric density and its time history are incorporated into the analysis to provide a final orbit that satisfies planetary quarantine requirements.

  18. Magnetic Attitude Control for Satellites in Polar or Sun-Synchronous Orbits

    OpenAIRE

    Cubas Cano, Javier; Farrahi, Assal; Pindado Carrion, Santiago

    2015-01-01

    In this work, a new law for magnetic control of satellites in near-polar orbits is presented. This law has been developed for the UMPSat-2 microsatellite, which has been designed and manufactured by Universidad Politécnica de Madrid, Madrid. The control law is a modification of the B-dot strategy that enables the satellite to control the rotation rate. Besides, the satellite?s equilibrium state is characterized by having the rotation axis perpendicular to the orbit?s plane. The control law de...

  19. Polarized Structure Function of Nucleon and Orbital Angular Momentum

    Science.gov (United States)

    Arash, Firooz; Taghavi-Shahri, Fatemeh

    2007-06-01

    We have utilized the concept of valon model to calculate the spin structure function of a constituent quark. This structure is universal and arises from perturbative dressing of a valence quark in QCD. With a convolution method the polarized structure functions of proton, neutron, and deuteron are obtained. Our results agree rather well with all available experimental data. It suggests that the sea quark contribution to the spin of nucleon is consistent with zero, in agreement with HERMES data. It also reveals that while the total quark contribution to the spin of a constituent quark, or valon, is almost constant and equal to one, the gluon contribution grows with the increase of Q2, and hence, requiring a sizable negative angular momentum contribution. This component, as well as singlet and non-singlet parts are calculated in the Next-to-Leading order in QCD. We speculate that the gluon contribution to the spin of proton is in the order of 50%. Furthermore, we have determined the polarized valon distribution in a nucleon.

  20. Influence of orbital precession on the polar methane accumulation on Titan

    Science.gov (United States)

    Liu, J.; Schneider, T.

    2014-12-01

    Data collected by Cassini Spacecraft indicate that lakes on Titan are primarily found in the polar regions, preferentially in the north. It has been suggested that the hemispherical asymmetry in lake distribution is related to Saturn's orbital precession, which changes the seasonal distribution of solar radiation on Titan, but not the annual mean (Aharonson et al., 2009; Schneider et al., 2012). Saturn's current longitude of perihelion is near northern winter solstice. Hence, the northern summer on Titan is longer and less intense than the southern summer. The longer northern summer leads to greater net precipitation in the annual mean and the methane accumulation over the northern polar region (Schneider et al. 2012). Saturn's perihelion precesses over an approximately 45-kyr period, so the solar radiation at the top of Titan's atmosphere varies on this time scale. Here we investigate how the orbital precession influences the polar methane accumulation with a three-dimensional atmospheric model coupled to a dynamic surface reservoir of methane (Schneider et al. 2012). We find that methane accumulation is closely tied to Saturn's orbital precession. At the time when Saturn's longitude of perihelion is 180 degree away from the present day value, methane is mainly accumulated in the southern polar region due to the stronger annual-mean precipitation there induced by the longer southern summer. The annual-mean evaporation is largely unchanged with orbital precession, since it scales with the annual-mean insolation, which does not change under orbital precession. When Saturn's longitude of perihelion is close to equinox, methane is approximately evenly distributed in the northern and southern polar regions, and the lake dichotomy disappears. The timescale of methane redistribution from one pole to the other is short compared with the timescale of orbital precession, so the surface methane distribution can be viewed as being approximately in equilibrium with the solar

  1. A permanent magnet hall thruster for pulsed orbit control of lunar polar satellites

    International Nuclear Information System (INIS)

    Future Moon missions devoted to Lunar surface remote sensing, for example, will require very fine and accurate orbit control. It is well known that Lunar satellites in polar orbits will suffer a high increase on the eccentricity due to the gravitational perturbation of the Earth. Without proper orbit correction the satellite lifetime will decrease and end up in a collision with the Moon surface. It is pointed out by many authors that this effect is a natural consequence of the Lidov-Kozai resonance. We studied different arcs of active lunar satellite propulsion, centered on the orbit apoapsis or periapsis, in order to be able to introduce a correction of the eccentricity at each cycle. The proposed method is based on an approach intended to keep the orbital eccentricity of the satellite at low values.

  2. A Permanent Magnet Hall Thruster for Pulsed Orbit Control of Lunar Polar Satellites

    Science.gov (United States)

    Silva Moraes, Brunno; Ferreira, José Leonardo; Soares Ferreira, Ivan; Cabo Winter, Othon; Cardozo Mourão, Décio

    2014-05-01

    Future Moon missions devoted to Lunar surface remote sensing, for example, will require very fine and accurate orbit control. It is well known that Lunar satellites in polar orbits will suffer a high increase on the eccentricity due to the gravitational perturbation of the Earth. Without proper orbit correction the satellite lifetime will decrease and end up in a collision with the Moon surface. It is pointed out by many authors that this effect is a natural consequence of the Lidov-Kozai resonance. We studied different arcs of active lunar satellite propulsion, centered on the orbit apoapsis or periapsis, in order to be able to introduce a correction of the eccentricity at each cycle. The proposed method is based on an approach intended to keep the orbital eccentricity of the satellite at low values.

  3. A NEARLY POLAR ORBIT FOR THE EXTRASOLAR HOT JUPITER WASP-79b

    International Nuclear Information System (INIS)

    We report the measurement of a spin-orbit misalignment for WASP-79b, a recently discovered, bloated hot Jupiter from the Wide Angle Search for Planets (WASP) survey. Data were obtained using the CYCLOPS2 optical-fiber bundle and its simultaneous calibration system feeding the UCLES spectrograph on the Anglo-Australian Telescope. We have used the Rossiter-McLaughlin effect to determine the sky-projected spin-orbit angle to be λ= -106+19-13o. This result indicates a significant misalignment between the spin axis of the host star and the orbital plane of the planet—the planet being in a nearly polar orbit. WASP-79 is consistent with other stars that have Teff > 6250 K and host hot Jupiters in spin-orbit misalignment

  4. A Nearly Polar Orbit for the Extrasolar Hot Jupiter WASP-79b

    CERN Document Server

    Addison, B C; Wright, D J; Bayliss, D; Zhou, G; Hartman, J D; Bakos, G Á; Schmidt, B

    2013-01-01

    We report the measurement of a spin-orbit misalignment for WASP-79b, a recently discovered, extremely bloated transiting hot Jupiter from the WASP survey. Data were obtained using the CYCLOPS2 optical-fiber bundle and its simultaneous calibration system feeding the UCLES spectrograph on the Anglo-Australian Telescope at the Siding Spring Observatory. We have used the Rossiter-McLaughlin effect to determine the sky-projected spin-orbit angle to be lambda = -106+10-8 degrees. This result indicates a significant misalignment between the spin axis of the host star and the orbital plane of the planet -- the planet being in a nearly polar orbit. WASP-79 is consistent with other stars that have Teff > 6250K and host hot Jupiters in spin-orbit misalignment.

  5. Polarization-insensitive PAM-4-carrying free-space orbital angular momentum (OAM) communications.

    Science.gov (United States)

    Liu, Jun; Wang, Jian

    2016-02-22

    We present a simple configuration incorporating single polarization-sensitive phase-only liquid crystal spatial light modulator (SLM) to facilitate polarization-insensitive free-space optical communications employing orbital angular momentum (OAM) modes. We experimentally demonstrate several polarization-insensitive optical communication subsystems by propagating a single OAM mode, multicasting 4 and 10 OAM modes, and multiplexing 8 OAM modes, respectively. Free-space polarization-insensitive optical communication links using OAM modes that carry four-level pulse-amplitude modulation (PAM-4) signal are demonstrated in the experiment. The observed optical signal-to-noise ratio (OSNR) penalties are less than 1 dB in both polarization-insensitive N-fold OAM modes multicasting and multiple OAM modes multiplexing at a bit-error rate (BER) of 2e-3 (enhanced forward-error correction (EFEC) threshold). PMID:26907073

  6. Wave particle interactions in the high-altitude polar cusp: a Cluster case study

    Directory of Open Access Journals (Sweden)

    B. Grison

    2005-12-01

    Full Text Available On 23 March 2002, the four Cluster spacecraft crossed in close configuration (~100 km separation the high-altitude (10 RE cusp region. During a large part of the crossing, the STAFF and EFW instruments have detected strong electromagnetic wave activity at low frequencies, especially when intense field-aligned proton fluxes were detected by the CIS/HIA instrument. In all likelihood, such fluxes correspond to newly-reconnected field lines. A focus on one of these ion injection periods highlights the interaction between waves and protons. The wave activity has been investigated using the k-filtering technique. Experimental dispersion relations have been built in the plasma frame for the two most energetic wave modes. Results show that kinetic Alfvén waves dominate the electromagnetic wave spectrum up to 1 Hz (in the spacecraft frame. Above 0.8 Hz, intense Bernstein waves are also observed. The close simultaneity observed between the wave and particle events is discussed as an evidence for local wave generation. A mechanism based on current instabilities is consistent with the observations of the kinetic Alfvén waves. A weak ion heating along the recently-opened field lines is also suggested from the examination of the ion distribution functions. During an injection event, a large plasma convection motion, indicative of a reconnection site location, is shown to be consistent with the velocity perturbation induced by the large-scale Alfvén wave simultaneously detected.

  7. Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit.

    Science.gov (United States)

    El-Jaby, Samy; Richardson, Richard B

    2015-07-01

    Occupational exposures from ionizing radiation are currently regulated for airline travel (International Space Station, the area radiation dose equivalent measured over just 168 days was 106 mSv at solar minimum conditions. It is anticipated that space tourism vehicles will reach suborbital altitudes of approximately 100 km and, therefore, the annual occupational dose to flight crew during repeated transits is expected to fall somewhere between those observed for aircrew and astronauts. Unfortunately, measurements of the radiation environment at the high altitudes reached by suborbital vehicles are sparse, and modelling efforts have been similarly limited. In this paper, preliminary MCNPX radiation transport code simulations are developed of the secondary neutron flux profile in air from surface altitudes up to low Earth orbit at solar minimum conditions and excluding the effects of spacecraft shielding. These secondary neutrons are produced by galactic cosmic radiation interacting with Earth's atmosphere and are among the sources of radiation that can pose a health risk. Associated estimates of the operational neutron ambient dose equivalent, used for radiation protection purposes, and the neutron effective dose equivalent that is typically used for estimates of stochastic health risks, are provided in air. Simulations show that the neutron radiation dose rates received at suborbital altitudes are comparable to those experienced by aircrew flying at 7 to 14 km. We also show that the total neutron dose rate tails off beyond the Pfotzer maximum on ascension from surface up to low Earth orbit. PMID:26256622

  8. Monte Carlo simulations of the secondary neutron ambient and effective dose equivalent rates from surface to suborbital altitudes and low Earth orbit

    Science.gov (United States)

    El-Jaby, Samy; Richardson, Richard B.

    2015-07-01

    Occupational exposures from ionizing radiation are currently regulated for airline travel (tourism vehicles will reach suborbital altitudes of approximately 100 km and, therefore, the annual occupational dose to flight crew during repeated transits is expected to fall somewhere between those observed for aircrew and astronauts. Unfortunately, measurements of the radiation environment at the high altitudes reached by suborbital vehicles are sparse, and modelling efforts have been similarly limited. In this paper, preliminary MCNPX radiation transport code simulations are developed of the secondary neutron flux profile in air from surface altitudes up to low Earth orbit at solar minimum conditions and excluding the effects of spacecraft shielding. These secondary neutrons are produced by galactic cosmic radiation interacting with Earth's atmosphere and are among the sources of radiation that can pose a health risk. Associated estimates of the operational neutron ambient dose equivalent, used for radiation protection purposes, and the neutron effective dose equivalent that is typically used for estimates of stochastic health risks, are provided in air. Simulations show that the neutron radiation dose rates received at suborbital altitudes are comparable to those experienced by aircrew flying at 7 to 14 km. We also show that the total neutron dose rate tails off beyond the Pfotzer maximum on ascension from surface up to low Earth orbit.

  9. Martian Polar Impact Craters: A Preliminary Assessment Using Mars Orbiter Laser Altimeter (MOLA)

    Science.gov (United States)

    Sakimoto, S. E. H.; Garvin, J. B.

    1999-01-01

    Our knowledge of the age of the layered polar deposits and their activity in the volatile cycling and climate history of Mars is based to a large extent on their apparent ages as determined from crater counts. Interpretation of the polar stratigraphy (in terms of climate change) is complicated by reported differences in the ages of the northern and southern layered deposits. The north polar residual ice deposits are thought to be relatively young, based on the reported lack of any fresh impact craters in Viking Orbiter Images. Herkenhoff et al., report no craters at all on the North polar layered deposits or ice cap, and placed an upper bound on the surface age (or, alternatively, the vertical resurfacing rate) of 100 thousand years to 10 million years, suggesting that the north polar region is an active resurfacing site. In contrast, the southern polar region was found to have at least 15 impact craters in the layered deposits and cap. Plaut et al, concluded that the surface was less than or = 120 million years old. This reported age difference factor of 100 to 1000 increases complexity in climate and volatile modeling. Recent MOLA results for the topography of the northern polar cap document a handful or more of possible craters, which could result in revised age or resurfacing estimates for the northern cap. This study is a preliminary look at putative craters in both polar caps. Additional information is contained in the original extended abstract.

  10. Orbital geometry determined by orthogonal high-order harmonic polarization components

    International Nuclear Information System (INIS)

    We study the polarization state of high-order harmonics produced by linearly polarized light interacting with two-center molecules. By generating high-harmonic 'polarization maps' from Radon transformations of excited electronic wave functions, we show that the polarization of the harmonic radiation can be linked to the geometry of the molecular orbital. While in the Radon transformation the plane-wave approximation for the rescattered electron is implicitly assumed, numerical solutions of the two-dimensional time-dependent Schro··dinger equation, in which this approximation is not made, confirm the validity of this topological connection. We also find that measuring two orthogonal amplitude components of the harmonics provides a method for quantum tomography that substantially improves the quality of reconstructed molecular states.

  11. Spin-orbit and core/valence polarization effects in molecular electronic states

    International Nuclear Information System (INIS)

    Relativistic core-valence polarization potentials that incorporate spin-orbit coupling effects are developed for use with relativistic effective core potentials in ab initio calculations on many-electron systems. These potentials effectively lower the number of electrons that must be explicitly included in such calculations without significant loss in accuracy. This reduction in the number of electrons makes tractable the inclusion of correlation and intermediate angular momentum coupling corrections, which are of particular importance in heavy-element molecules. Calculations of electronic spectra are reported for dimers of Group IA and IIA elements at the full spin-orbit configuration interaction level of theory

  12. Polar Dunes Resolved by the Mars Orbiter Laser Altimeter Gridded Topography and Pulse Widths

    Science.gov (United States)

    Neumann, Gregory A.

    2003-01-01

    The Mars Orbiter Laser Altimeter (MOLA) polar data have been refined to the extent that many features poorly imaged by Viking Orbiters are now resolved in densely gridded altimetry. Individual linear polar dunes with spacings of 0.5 km or more can be seen as well as sparsely distributed and partially mantled dunes. The refined altimetry will enable measurements of the extent and possibly volume of the north polar ergs. MOLA pulse widths have been recalibrated using inflight data, and a robust algorithm applied to solve for the surface optical impulse response. It shows the surface root-mean-square (RMS) roughness at the 75-m-diameter MOLA footprint scale, together with a geological map. While the roughness is of vital interest for landing site safety studies, a variety of geomorphological studies may also be performed. Pulse widths corrected for regional slope clearly delineate the extent of the polar dunes. The MOLA PEDR profile data have now been re-released in their entirety (Version L). The final Mission Experiment Gridded Data Records (MEGDR's) are now provided at up to 128 pixels per degree globally. Densities as high as 512 pixels per degree are available in a polar stereographic projection. A large computational effort has been expended in improving the accuracy of the MOLA altimetry themselves, both in improved orbital modeling and in after-the-fact adjustment of tracks to improve their registration at crossovers. The current release adopts the IAU2000 rotation model and cartographic frame recommended by the Mars Cartography Working Group. Adoption of the current standard will allow registration of images and profiles globally with an uncertainty of less than 100 m. The MOLA detector is still operational and is currently collecting radiometric data at 1064 nm. Seasonal images of the reflectivity of the polar caps can be generated with a resolution of about 300 m per pixel.

  13. Spin-orbit-induced spin splittings in polar transition metal dichalcogenide monolayers

    KAUST Repository

    Cheng, Yingchun

    2013-06-01

    The Rashba effect in quasi two-dimensional materials, such as noble metal surfaces and semiconductor heterostructures, has been investigated extensively, while interest in real two-dimensional systems has just emerged with the discovery of graphene. We present ab initio electronic structure, phonon, and molecular-dynamics calculations to study the structural stability and spin-orbit-induced spin splitting in the transition metal dichalcogenide monolayers MXY (M = Mo, W and X, Y = S, Se, Te). In contrast to the non-polar systems with X = Y, in the polar systems with X ≠ Y the Rashba splitting at the Γ-point for the uppermost valence band is caused by the broken mirror symmetry. An enhancement of the splitting can be achieved by increasing the spin-orbit coupling and/or the potential gradient. © Copyright EPLA, 2013.

  14. Explicit Polarization (X-Pol) Potential Using ab Initio Molecular Orbital Theory and Density Functional Theory†

    OpenAIRE

    Song, Lingchun; Han, Jaebeom; Lin, Yen-lin; Xie, Wangshen; Gao, Jiali

    2009-01-01

    The explicit polarization (X-Pol) method has been examined using ab initio molecular orbital theory and density functional theory. The X-Pol potential was designed to provide a novel theoretical framework for developing next-generation force fields for biomolecular simulations. Importantly, the X-Pol potential is a general method, which can be employed with any level of electronic structure theory. The present study illustrates the implementation of the X-Pol method using ab initio Hartree—Fo...

  15. Q-plates as higher order polarization controllers for orbital angular momentum modes of fiber.

    Science.gov (United States)

    Gregg, P; Mirhosseini, M; Rubano, A; Marrucci, L; Karimi, E; Boyd, R W; Ramachandran, S

    2015-04-15

    We demonstrate that a |q|=1/2 plate, in conjunction with appropriate polarization optics, can selectively and switchably excite all linear combinations of the first radial mode order |l|=1 orbital angular momentum (OAM) fiber modes. This enables full mapping of free-space polarization states onto fiber vector modes, including the radially (TM) and azimuthally polarized (TE) modes. The setup requires few optical components and can yield mode purities as high as ∼30  dB. Additionally, just as a conventional fiber polarization controller creates arbitrary elliptical polarization states to counteract fiber birefringence and yield desired polarizations at the output of a single-mode fiber, q-plates disentangle degenerate state mixing effects between fiber OAM states to yield pure states, even after long-length fiber propagation. We thus demonstrate the ability to switch dynamically, potentially at ∼GHz rates, between OAM modes, or create desired linear combinations of them. We envision applications in fiber-based lasers employing vector or OAM mode outputs, as well as communications networking schemes exploiting spatial modes for higher dimensional encoding. PMID:25872059

  16. Polarization singularities and orbital angular momentum sidebands from rotational symmetry broken by the Pockels effect

    Science.gov (United States)

    Lu, Xiancong; Wu, Ziwen; Zhang, Wuhong; Chen, Lixiang

    2014-01-01

    The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved. PMID:24784778

  17. Polarized Parton Distribution, Orbital Angular Momentum, and the Violation of a8

    Science.gov (United States)

    Arash, Firooz; Taghavi-Shahri, Fatemeh

    2009-03-01

    We use the so-called valon model, to describe the spin structure of the nucleon. We show that about 40% of the nucleon spin is carried by the polarized valence quarks. The remaining part comes from the gluon polarization and the orbital angular momentum. It is shown that the sea quark contributions to the spin of any hadron is simply marginal and consistent with zero. We also found that the value of a8 is substantially smaller than the value inferred from hyperon—β decay, suggesting that full SU(3) symmetric assumption needs to be reconsidered. New and emerging experimental data tend to support this finding. Finally, we show that within the model presented here the experimental data on the polarized structure functions g1p,n,d are reproduced.

  18. A planet in a polar orbit of 1.4 solar-mass star

    Directory of Open Access Journals (Sweden)

    Guenther E.W.

    2015-01-01

    Full Text Available Although more than a thousand transiting extrasolar planets have been discovered, only very few of them orbit stars that are more massive than the Sun. The discovery of such planets is interesting, because they have formed in disks that are more massive but had a shorter life time than those of solar-like stars. Studies of planets more massive than the Sun thus tell us how the properties of the proto-planetary disks effect the formation of planets. Another aspect that makes these planets interesting is that they have kept their original orbital inclinations. By studying them we can thus find out whether the orbital axes planets are initially aligned to the stars rotational axes, or not. Here we report on the discovery of a planet of a 1.4 solar-mass star with a period of 5.6 days in a polar orbit made by CoRoT. This new planet thus is one of the few known close-in planets orbiting a star that is substantially more massive than the Sun.

  19. Statistics of a parallel Poynting vector in the auroral zone as a function of altitude using Polar EFI and MFE data and Astrid-2 EMMA data

    Directory of Open Access Journals (Sweden)

    P. Janhunen

    2005-07-01

    Full Text Available We study the wave-related (AC and static (DC parallel Poynting vector (Poynting energy flux as a function of altitude in auroral field lines using Polar EFI and MFE data. The study is statistical and contains 5 years of data in the altitude range 5000–30000 km. We verify the low altitude part of the results by comparison with earlier Astrid-2 EMMA Poynting vector statistics at 1000 km altitude. The EMMA data are also used to statistically compensate the Polar results for the missing zonal electric field component. We compare the Poynting vector with previous statistical DMSP satellite data concerning the electron precipitation power. We find that the AC Poynting vector (Alfvén-wave related Poynting vector is statistically not sufficient to power auroral electron precipitation, although it may, for Kp>2, power 25–50% of it. The statistical AC Poynting vector also has a stepwise transition at R=4 RE, so that its amplitude increases with increasing altitude. We suggest that this corresponds to Alfvén waves being in Landau resonance with electrons, so that wave-induced electron acceleration takes place at this altitude range, which was earlier named the Alfvén Resonosphere (ARS. The DC Poynting vector is ~3 times larger than electron precipitation and corresponds mainly to ionospheric Joule heating. In the morning sector (02:00–06:00 MLT we find that the DC Poynting vector has a nontrivial altitude profile such that it decreases by a factor of ~2 when moving upward from 3 to 4 RE radial distance. In other nightside MLT sectors the altitude profile is more uniform. The morning sector nontrivial altitude profile may be due to divergence of the perpendicular Poynting vector field at R=3–4 RE.

    Keywords. Magnetospheric physics (Auroral phenomena; Magnetosphere-ionosphere interactions – Space plasma physics (Wave-particle interactions

  20. Polarization Possibilities of Small Spin-Orbit Interaction in Strained-Superlattice Photocathodes

    Energy Technology Data Exchange (ETDEWEB)

    2010-08-25

    Strained-superlattice photocathodes based on InGaP/GaAs were investigated. The photocathode performance is found highly dependent on the superlattice parameters. The electron confinement energy in superlattice appears important. The strained-superlattice structure based on GaAsP/GaAs, with a maximum polarization as high as 90% and more than 1% quantum efficiency, is presently the prime candidate for the ILC polarized electron photocathodes. A recent systematic study shows, however, that the peak polarization seems saturated even though the heavy-hole (HH) and light-hole (LH) band splitting is increased significantly, indicating that there is a material specific spin relaxation mechanism. It is widely accepted that the D'yakonov-Perel mechanism is the dominant spin relaxation mechanism in the III-V compound superlattice structures with a low p-doping ({le} 10{sup 17} cm{sup -3}), and that the spin relaxation may be reduced by choosing a material with a smaller spin-orbit interaction. As the spin-orbit interaction in phosphides is much smaller than in arsenides, strained-superlattice structure based on InGaP/GaAs were investigated. The computer code SPECCODE developed by Subashiev and Gerchikov has been used for calculating the band structures in superlattice.

  1. Controlling Rashba spin orbit coupling in polar two-dimensional transition metal dichalcogenide

    CERN Document Server

    Yao, Qun-Fang; Tong, Wen-Yi; Gong, Shi-Jing; Wang, Ji-Qing; Wan, Xian-gang; Duan, Chun-Gang; Chu, J H

    2016-01-01

    Monolayer transition metal dichalcogenide (TMD) group of materials MXY (M=Mo, W, X(not equal to)Y=S, Se, Te) are two-dimensional polar semiconductors with Rashba spin orbit coupling (SOC). Setting WSeTe as an example and using density functional theory calculations, we investigate the influence of biaxial strain and electric field on Rashba SOC in MXY monolayer. The orbital analysis reveals that Rashba spin splitting around Gamma point occurs mainly through the SOC matrix elements between the W-dz2 and -dxz/yz orbitals, and those between the Se-pz and -px/y orbitals. We find the change of local electric field between Se and W atoms arising from the mirror symmetry breaking plays the critical role in forming the large Rashba SOC, and through a relatively small compressive/tensile strain (from -2% to 2%), a large tunability of Rashba SOC can be obtained due to the modified W-Se bonding interaction. In addition, we also explore the influence of electric field on Rashba SOC in WSeTe, which can impact the charge d...

  2. Imprints of molecular orbitals using photoelectron angular distribution by strong laser pulses of circular polarization

    Institute of Scientific and Technical Information of China (English)

    Ren Xiang-He; Wu Yan; Zhang Jing-Tao; Ma Hui; Xu Yu-Long

    2013-01-01

    We theoretically investigate the strong-field ionization of H2+ molecules in four different electronic states by calculating photoelectron angular distributions in circularly polarized fields.We find that the structure of photoelectron angular distribution depends on the molecular orbital as well as the energy of the photoelectron.The location of main lobes changes with the symmetric property of the molecular orbital.Generally,for molecules with bonding electronic states,the photoelectron's angular distribution shows a rotation of π/2 with respect to the molecular axis,while for molecules with antibonding electronic states,no rotation occurs.We use an interference scenario to interpret these phenomena.We also find that,due to the interference effect,a new pair of jets appears in the waist of the main lobes,and the main lobes or jets of the photoelectron's angular distribution are split into two parts if the photoelectron energy is sufficiently high.

  3. Detecting Canopy Water Status Using Shortwave Infrared Reflectance Data From Polar Orbiting and Geostationary Platforms

    DEFF Research Database (Denmark)

    Fensholt, Rasmus; Huber Gharib, Silvia; Proud, Simon Richard;

    2010-01-01

    Various canopy water status estimates have been developed from recent advances in Earth Observation (EO) technology. A promising methodology is based on the sensitivity of shortwave infrared (SWIR) reflectance to variations in leaf water content. This study explores the potential of SWIR......-based canopy water status detection from geostationary Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI) data as compared to polar orbiting environmental satellite (POES)-based moderate resolution imaging spectroradiometer (MODIS) data. The EO-based SWIR water stress index...... for SWIR-based canopy water status and stress monitoring in a semi-arid environment....

  4. A search for spin-polarized photoemission from GaAs using light with orbital angular momentum

    Energy Technology Data Exchange (ETDEWEB)

    Nathan Clayburn, James McCarter, Joan Dreiling, Bernard Poelker, Dominic Ryan, Timothy Gay

    2013-01-01

    Laser light with photon energy near the bandgap of GaAs and with different amounts of orbital angular momentum was used to produce photoemission from unstrained GaAs. The degree of electron spin polarization was measured using a micro-Mott polarimeter and found to be consistent with zero with an upper limit of ~3% for light with up to ±5{bar h} of orbital angular momentum. In contrast, the degree of spin polarization was 32.32 ± 1.35% using circularly-polarized laser light at the same wavelength, which is typical of bulk GaAs.

  5. Polarization modulators based on liquid crystal variable retarders for the Solar Orbiter mission

    Science.gov (United States)

    Alvarez-Herrero, A.; García Parejo, P.; Laguna, H.; Villanueva, J.; Barandiarán, J.; Bastide, L.; Reina, M.; Sánchez, A.; Gonzalo, A.; Navarro, R.; Vera, I.; Royo, M.

    2015-09-01

    A polarization modulator based on Liquid Crystal Variable Retarders (LCVRs) will be used in the Polarimetric and Helioseismic Imager (PHI) for the Solar Orbiter mission to measure the complete Stokes vector of the incoming light. PHI is one of the six remote sensing instruments onboard of this space mission led by the European Space Agency (ESA) with strong NASA participation. It is an imaging spectro-polarimeter that will acquire high resolution solar magnetograms. Also the LCVRs will be used in the polarization modulator of the METIS instrument (Multi Element Telescope for Imaging and Spectroscopy). METIS is a solar coronagraph that will analyze the linear polarization for observations of the visible-light K-corona. The polarization modulators are described in this work including the optical, mechanical, thermal and electrical aspects. Both modulators will consist of two identical LCVRs with a relative azimuth orientation of 45º for PHI and parallel for the METIS modulator. In the first case, the configuration allows the analysis of the full Stokes vector with maximum polarimetric efficiencies. In the second setup, wide acceptance angles (verification and environmental test campaign in progress currently. The main performances were measured and analyzed including polarimetric efficiencies, wavefront error transmission, beam deviation and transmittance. This valuable information will allow to consolidate the detailed design of these devices increasing its TRL to 6 and to proceed to the manufacturing of the Qualification Model (QM) and Flight Models (FM).

  6. Spin-polarized current through a lateral double quantum dot with spin-orbit interaction

    International Nuclear Information System (INIS)

    We study the spin-polarized current through a vertical double quantum dot scheme. Both the Rashba spin-orbit (RSO) interaction inside one of the quantum dots and the strong intradot Coulomb interactions on the two dots are taken into account by using the second-quantized form of the Hamiltonian. Due to the existence of the RSO interaction, spin-up and spin-down electrons couple to the external leads with different strengths, and then a spin polarized current can be driven out of the middle lead by controlling a set of structure parameters and the external bias voltage. Moreover, by properly adjusting the dot levels and the external bias voltages, a pure spin current with no accompanying charge current can be generated in the weak coupling regime. We show that the difference between the intradot Coulomb interactions strongly influences the spin-polarized currents flowing through the middle lead and is undesirable in the generation of the net spin current. Based on the RSO interaction, the structure we propose can efficiently polarize the electron spin without the usage of any magnetic field or ferromagnetic material. This device can be used as a spin-battery and is realizable using the present available technologies

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

    International Nuclear Information System (INIS)

    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 3sin i' = 0.00600(±0.00055) M sun = 6.28(±0.58) M Jupiter when a total mass of 0.69 M sun is adopted. If the tertiary companion is coplanar to the eclipsing binary (i.e., i' = 79.05), it should be a giant extrasolar planet with a mass of 6.39 M 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.

  8. The case for a modern multiwavelength, polarization-sensitive LIDAR in orbit around Mars

    International Nuclear Information System (INIS)

    We present the scientific case to build a multiple-wavelength, active, near-infrared (NIR) instrument to measure the reflected intensity and polarization characteristics of backscattered radiation from planetary surfaces and atmospheres. We focus on the ability of such an instrument to enhance, potentially revolutionize, our understanding of climate, volatiles and astrobiological potential of modern-day Mars. Such an instrument will address the following three major science themes, which we address in this paper: Science Theme 1. Surface. This would include global, night and day mapping of H2O and CO2 surface ice properties. Science Theme 2. Ice Clouds. This would including unambiguous discrimination and seasonal mapping of CO2 and H2O ice clouds. Science Theme 3. Dust Aerosols. This theme would include multiwavelength polarization measurements to infer dust grain shapes and size distributions. - Highlights: • We present the scientific rationale for a multi-wavelength, polarization sensitive lidar to be placed in orbit around Mars. • Scientific questions focus on the Martian climate and modern-day interactions between surface, ice clouds and dust aerosols. • What we would learn about volatile transport and deposition has implications for past, present and future life on Mars

  9. Observations of the north polar region of Mars from the Mars orbiter laser altimeter.

    Science.gov (United States)

    Zuber, M T; Smith, D E; Solomon, S C; Abshire, J B; Afzal, R S; Aharonson, O; Fishbaugh, K; Ford, P G; Frey, H V; Garvin, J B; Head, J W; Ivanov, A B; Johnson, C L; Muhleman, D O; Neumann, G A; Pettengill, G H; Phillips, R J; Sun, X; Zwally, H J; Banerdt, W B; Duxbury, T C

    1998-12-11

    Elevations from the Mars Orbiter Laser Altimeter (MOLA) have been used to construct a precise topographic map of the martian north polar region. The northern ice cap has a maximum elevation of 3 kilometers above its surroundings but lies within a 5-kilometer-deep hemispheric depression that is contiguous with the area into which most outflow channels emptied. Polar cap topography displays evidence of modification by ablation, flow, and wind and is consistent with a primarily H2O composition. Correlation of topography with images suggests that the cap was more spatially extensive in the past. The cap volume of 1.2 x 10(6) to 1.7 x 10(6) cubic kilometers is about half that of the Greenland ice cap. Clouds observed over the polar cap are likely composed of CO2 that condensed out of the atmosphere during northern hemisphere winter. Many clouds exhibit dynamical structure likely caused by the interaction of propagating wave fronts with surface topography. PMID:9851922

  10. Tunable ferroelectric polarization and its interplay with spin-orbit coupling in tin iodide perovskites.

    Science.gov (United States)

    Stroppa, Alessandro; Di Sante, Domenico; Barone, Paolo; Bokdam, Menno; Kresse, Georg; Franchini, Cesare; Whangbo, Myung-Hwan; Picozzi, Silvia

    2014-01-01

    Ferroelectricity is a potentially crucial issue in halide perovskites, breakthrough materials in photovoltaic research. Using density functional theory simulations and symmetry analysis, we show that the lead-free perovskite iodide (FA)SnI3, containing the planar formamidinium cation FA, (NH2CHNH2)(+), is ferroelectric. In fact, the perpendicular arrangement of FA planes, leading to a 'weak' polarization, is energetically more stable than parallel arrangements of FA planes, being either antiferroelectric or 'strong' ferroelectric. Moreover, we show that the 'weak' and 'strong' ferroelectric states with the polar axis along different crystallographic directions are energetically competing. Therefore, at least at low temperatures, an electric field could stabilize different states with the polarization rotated by π/4, resulting in a highly tunable ferroelectricity appealing for multistate logic. Intriguingly, the relatively strong spin-orbit coupling in noncentrosymmetric (FA)SnI3 gives rise to a co-existence of Rashba and Dresselhaus effects and to a spin texture that can be induced, tuned and switched by an electric field controlling the ferroelectric state. PMID:25533044

  11. Solar Wind Influence on the Oxygen Content of Ion Outflow in the High-Altitude Polar Cap During Solar Minimum Conditions

    Science.gov (United States)

    Elliott, H. A.; Comfort, R. H.; Craven, P. D.; Chandler, M. O.; Moore, T. E.

    2001-01-01

    We correlate solar wind and interplanetary magnetic field (IMF) properties with the properties of O(+) and H(+) during early 1996 (solar minimum) at altitudes between 5.5 and 8.9 R(sub E) geocentric using the Thermal Ion Dynamics Experiment (TIDE) on the Polar satellite. Throughout the high-altitude polar cap we observe H(+) to be more abundant than O(+). O(+) is found to be more abundant at lower latitudes when the solar wind speed is low (and Kp is low), while at higher solar wind speeds (and high Kp), O(+) is observed across most of the polar cap. The O(+) density and parallel flux are well organized by solar wind dynamic pressure, both increasing with solar wind dynamic pressure. Both the O(+) density and parallel flux have positive correlations with both V(sub SW)B(sub IMF) and E(sub SW). No correlation is found between O(+) density and IMF Bz, although a nonlinear relationship with IMF By is observed, possibly due to a strong linear correlation with the dynamic pressure. H(+) is not as highly correlated with solar wind and IMF parameters, although H(+) density and parallel flux are negatively correlated with IMF By and positively correlated with both V(sub SW)B(sub IMF) and E(sub SW). In this solar minimum data set, H(+) is dominant, so that contributions of this plasma to the plasma sheet would have very low O(+) to H(+) ratios.

  12. Polarization-controlled evolution of light transverse modes and associated Pancharatnam geometric phase in orbital angular momentum

    International Nuclear Information System (INIS)

    We present an easy, efficient, and fast method to generate arbitrary linear combinations of light orbital angular-momentum eigenstates l=±2 starting from a linearly polarized TEM00 laser beam. The method exploits the spin-to-orbital angular-momentum conversion capability of a liquid-crystal-based q plate and a Dove prism inserted into a Sagnac polarizing interferometer. The nominal generation efficiency is 100%, being limited only by reflection and scattering losses in the optical components. When closed paths are followed on the polarization Poincare sphere of the input beam, the associated Pancharatnam geometric phase is transferred unchanged to the orbital angular momentum state of the output beam.

  13. Assessing Sahelian vegetation and stress from seasonal time series of polar orbiting and geostationary satellite imagery

    DEFF Research Database (Denmark)

    Olsen, Jørgen Lundegaard

    provide good sensitivity to canopy water content, which can make vegetation stress detection possible. Furthermore, the high frequency observations in the optical spectrum now available from geostationary instruments have the potential for detection of changes in vegetation related surface properties on...... short timescales, which are challenging from polar orbiting instruments. Geostationary NDVI and the NIR and SWIR based Shortwave Infrared Water Stress Index (SIWSI) indices are compared with extensive field data from the Dahra site, supplemented by data from the Agoufou and Demokeya sites. The indices...... are also compared with output from hydrological modelling of the Senegal River basin and a gridded rainfall product. It was shown that NIR/SWIR based indices are better suited for assessing water stress related changes in vegetation status, as compared to the more commonly applied NDVI. The hypothesis...

  14. GLOB(MET)SAT: French proposals for monitoring global change and weather from the polar orbit

    Science.gov (United States)

    Durpaire, Jean-Pierre; Ratier, A.; Dagras, C.

    1991-08-01

    A new concept for a polar orbiting satellite dedicated to global change research and its extension to fulfill the meteorological operational mission in the morning orbit is studied by CNES and MATRA, with the support of EUMETSAT and a group of European scientists. Two options were investigated during the feasibility study called GLOB(MET)SAT, the first one, GLOBSAT, restricted to an IGBP-dedicated mission, and the second one, GLOBMETSAT, combining this research mission and the operational met-mission specified by EUMETSAT. The mission objectives, the associated requirements, and the instruments accommodated are presented and discussed, as well as the main results of the phase A study for the space segment. The system configurations, characteristics, performances and the development plan are described. Both options prove feasible and compatible with a target launch date in the 1996-97 timeframe and preserve a significant growth potential. The use of the MK-2 platform developed for the SPOT-4 program and of other recurrent hardware elements appears a significant cost-saving, schedule-securing and reliability factor in both options. In the same line, the GLOBMETSAT system combining the environment and meteorological missions is of mutual benefit for both missions, in terms of reliability, cost sharing and use of platform resources, while keeping each mission independent and unaffected by the other.

  15. Target element dependent spin–orbit coupling in polarized {sup 4}He{sup +} ion scattering

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, T.T., E-mail: suzuki.taku@nims.go.jp [National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Sakai, O. [National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Ichinokura, S. [Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Hirahara, T. [Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Hasegawa, S. [Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2015-07-01

    We studied low-energy (1.57 keV) electron-spin polarized {sup 4}He{sup +} ion scattering on various 5d transition metal targets. The scattered ion intensity generally differed between the incident He{sup +} ions with up and down spins. This spin dependent ion scattering is attributed to the spin–orbit coupling (SOC) that acts transiently on the He{sup +} 1s electron spin in the He{sup +}-target binary collision. We observed that the amplitude of the spin dependence in ion scattering, i.e., the spin asymmetry, differs between 5d transition metal targets. This target element dependence of the spin asymmetry is discussed in terms of re-ionization of He{sup 0}, which originates from the neutralization of the He{sup +} ion during the He{sup +}-target collision. Since the re-ionization is spin independent process, it degrades the effective spin polarization of the He{sup +} ion beam. This explains smaller spin asymmetry with the target on which He{sup 0} is re-ionized with higher rate.

  16. Sunlight effects on the 3D polar current system determined from low Earth orbit measurements

    Science.gov (United States)

    Laundal, Karl M.; Finlay, Christopher C.; Olsen, Nils

    2016-08-01

    Interaction between the solar wind and the Earth's magnetosphere is associated with large-scale currents in the ionosphere at polar latitudes that flow along magnetic field lines (Birkeland currents) and horizontally. These current systems are tightly linked, but their global behaviors are rarely analyzed together. In this paper, we present estimates of the average global Birkeland currents and horizontal ionospheric currents from the same set of magnetic field measurements. The magnetic field measurements, from the low Earth orbiting Swarm and CHAMP satellites, are used to co-estimate poloidal and toroidal parts of the magnetic disturbance field, represented in magnetic apex coordinates. The use of apex coordinates reduces effects of longitudinal and hemispheric variations in the Earth's main field. We present global currents from both hemispheres during different sunlight conditions. The results show that the Birkeland currents vary with the conductivity, which depends most strongly on solar EUV emissions on the dayside and on particle precipitation at pre-midnight magnetic local times. In sunlight, the horizontal equivalent current flows in two cells, resembling an opposite ionospheric convection pattern, which implies that it is dominated by Hall currents. By combining the Birkeland current maps and the equivalent current, we are able to calculate the total horizontal current, without any assumptions about the conductivity. We show that the total horizontal current is close to zero in the polar cap when it is dark. That implies that the equivalent current, which is sensed by ground magnetometers, is largely canceled by the horizontal closure of the Birkeland currents.

  17. Manipulating the metal-to-insulator transition of NdNi O3 films by orbital polarization

    Science.gov (United States)

    Peng, J. J.; Song, C.; Wang, M.; Li, F.; Cui, B.; Wang, G. Y.; Yu, P.; Pan, F.

    2016-06-01

    We investigate the film thickness dependent metal-to-insulator transition temperature (TMIT) of NdNi O3 films under tensile and compressive strain states. For the films exceeding the critical thickness for strain relaxation, TMIT varies gradually with the film thickness caused by strain relaxation. The variation tendency differs dramatically for the films below the critical thickness: an increase (decrease) of TMIT with increasing the film thickness for the case of tensile (compressive) strain, which is attributed to the decaying of orbital polarization. As the overlap of O 2 px ,y orbits with Ni 3 d x2-y2 orbits determines TMIT, a decrease of x2-y2 orbital occupation with increasing film thickness would reduce the orbital overlap and resultant enhanced TMIT for tensile strained films, while their compressive counterparts do the opposite. Our findings identify the importance of orbital polarization in regulating the metal-to-insulator transitions, opening up a new perspective for orbital physics in transition metal oxides.

  18. Spin-orbit-induced photoelectron spin polarization in angle-resolved photoemission from both atomic and condensed matter targets

    International Nuclear Information System (INIS)

    The existence of highly spin polarized photoelectrons emitted from non-magnetic solids as well as from unpolarized atoms and molecules has been found to be very common in many studies over the past 40 years. This so-called Fano effect is based upon the influence of the spin-orbit interaction in the photoionization or the photoemission process. In a non-angle-resolved photoemission experiment, circularly polarized radiation has to be used to create spin polarized photoelectrons, while in angle-resolved photoemission even unpolarized or linearly polarized radiation is sufficient to get a high spin polarization. In past years the Rashba effect has become very important in the angle-resolved photoemission of solid surfaces, also with an observed high photoelectron spin polarization. It is the purpose of the present topical review to cross-compare the spin polarization experimentally found in angle-resolved photoelectron emission spectroscopy of condensed matter with that of free atoms, to compare it with the Rashba effect and topological insulators to describe the influence and the importance of the spin-orbit interaction and to show and disentangle the matrix element and phase shift effects therein. The relationship between the energy dispersion of these phase shifts and the emission delay of photoelectron emission in attosecond-resolved photoemission is also discussed. Furthermore the influence of chiral structures of the photo-effect target on the spin polarization, the interferences of different spin components in coherent superpositions in photoemission and a cross-comparison of spin polarization in photoemission from non-magnetic solids with XMCD on magnetic materials are presented; these are all based upon the influence of the spin-orbit interaction in angle-resolved photoemission. (topical review)

  19. Oscillating spin–orbit interaction as a source of spin-polarized wavepackets in two-terminal nanoscale devices

    International Nuclear Information System (INIS)

    Ballistic transport through nanoscale devices with time-dependent Rashba-type spin–orbit interaction (SOI) can lead to spin-polarized wavepackets that appear even for completely unpolarized input. The SOI that oscillates in a finite domain generates density and spin polarization fluctuations that leave the region as propagating waves. In particular, spin polarization has space and time dependence even in regions without SOI. Our results are based on an analytical solution of the time-dependent Schrödinger equation. The relevant Floquet quasi-energies that are obtained appear in the energy spectrum of both the transmitted and the reflected waves. (paper)

  20. Calibration of Suomi national polar-orbiting partnership advanced technology microwave sounder

    Science.gov (United States)

    Weng, Fuzhong; Zou, Xiaolei; Sun, Ninghai; Yang, Hu; Tian, Miao; Blackwell, William J.; Wang, Xiang; Lin, Lin; Anderson, Kent

    2013-10-01

    The Suomi National Polar-Orbiting Partnership (NPP) satellite was launched on 28 October 2011 and carries the Advanced Technology Microwave Sounder (ATMS) on board. ATMS is a cross-track scanning instrument observing in 22 channels at frequencies ranging from 23 to 183 GHz, permitting the measurements of the atmospheric temperature and moisture under most weather conditions. In this study, the ATMS radiometric calibration algorithm used in the operational system is first evaluated through independent analyses of prelaunch thermal vacuum data. It is found that the ATMS peak nonlinearity for all the channels is less than 0.5 K, which is well within the specification. For the characterization of the ATMS instrument sensitivity or noise equivalent differential temperatures (NEDT), both standard deviation and Allan variance of warm counts are computed and compared. It is shown that NEDT derived from the standard deviation is about three to five times larger than that from the Allan variance. The difference results from a nonstationary component in the standard deviation of warm counts. The Allan variance is better suited than the standard deviation for describing NEDT. In the ATMS sensor brightness temperature data record (SDR) processing algorithm, the antenna gain efficiencies of main beam, cross-polarization beam, and side lobes must be derived accurately from the antenna gain distribution function. However, uncertainties remain in computing the efficiencies at ATMS high frequencies. Thus, ATMS antenna brightness temperature data records (TDR) at channels 1 to 15 are converted to SDR with the actual beam efficiencies whereas those for channels 16 to 22 are only corrected for the near-field sidelobe contributions. The biases of ATMS SDR measurements to the simulations are consistent between GPS RO and NWP data and are generally less than 0.5 K for those temperature-sounding channels where both the forward model and input atmospheric profiles are reliable.

  1. Suomi National Polar-orbiting Partnership Environmental Data Records: Algorithm Status and Product Maturity

    Science.gov (United States)

    Csiszar, I. A.; Feeley, J.; Zhou, L.; Gottshall, E.

    2012-12-01

    The Joint Polar Satellite System's (JPSS) Data Processing Segment generates a number of environmental data products from measurements by sensors on the Suomi National Polar-orbiting Partnership (SNPP) satellite that launched on October 28, 2011. The JPSS Environmental Data Record (EDR) Algorithm Development and Validation teams have been carrying out detailed evaluation of the products. This work is stabilizing the EDR products and proposing the implementation of product improvements and major algorithm changes. Building on validation stages established by the National Aeronautics and Space Administration for their Earth Observing System program and adapted by the Committee on Earth Observation Satellites Working Group on Calibration and Validation, the JPSS program defined program-specific algorithm maturity stages. The JPSS definitions provide the rigor and comprehensiveness necessary for algorithm validation while serving the compliance needs for product requirements verification. Based on specific algorithm readiness levels, the JPSS EDR product teams established a schedule of anticipated dates for the algorithms to achieve Beta, Provisional and Validated Stage 1, 2 and 3 statuses. These schedules account for the products' dependencies on the maturity of input Sensor Data Records (SDRs), Intermediate Products, and upstream EDRs. Declaring EDR product maturity is the result of a specific review of artifacts that document that the products meet a series of criteria defined for each maturity stage. During 2012, after the SDR products achieved Beta maturity, a number of fundamental EDRs also achieved Beta status. They are now or will shortly become available to the public through the National Oceanic and Atmospheric Administration's (NOAA) Comprehensive Large Array-data Stewardship System (CLASS). In the presentation, we will provide an overview of the latest EDR algorithm updates and the maturity schedule going forward.

  2. The radiation protection problems of high altitude and space flight

    International Nuclear Information System (INIS)

    This paper considers the radiation environment in aircraft at high altitudes and spacecraft in low earth orbit and in deep space and the factors that influence the dose equivalents. Altitude, latitude and solar cycle are the major influences for flights below the radiation belts. In deep space, solar cycle and the occurrence of solar particle events are the factors of influence. The major radiation effects of concern are cancer and infertility in males. In high altitude aircraft the radiation consists mainly of protons and neutrons, with neutrons contributing about half the equivalent dose. The average dose rate at altitudes of transcontinental flights that approach the polar regions are greater by a factor of about 2.5 than on routes at low latitudes. Current estimates of does to air crews suggest they are well within the ICRP (1990) recommended dose limits for radiation workers

  3. $\\beta$ Pictoris' inner disk in polarized light and new orbital parameters for $\\beta$ Pictoris b

    CERN Document Server

    Millar-Blanchaer, Maxwell A; Pueyo, Laurent; Kalas, Paul; Dawson, Rebekah I; Wang, Jason; Perrin, Marshall; Moon, Dae-Sik; Macintosh, Bruce; Ammons, S Mark; Barman, Travis; Cardwell, Andrew; Chen, Christine H; Chiang, Eugene; Chilcote, Jeffrey; Cotten, Tara; De Rosa, Robert J; Draper, Zachary H; Dunn, Jennifer; Duchêne, Gaspard; Esposito, Thomas M; Fitzgerald, Michael P; Follette, Katherine B; Goodsell, Stephen J; Greenbaum, Alexandra Z; Hartung, Markus; Hibon, Pascale; Hinkley, Sasha; Ingraham, Patrick; Jensen-Clem, Rebecca; Konopacky, Quinn; Larkin, James E; Long, Douglas; Maire, Jérôme; Marchis, Franck; Marley, Mark S; Marois, Christian; Morzinski, Katie M; Nielsen, Eric L; Palmer, David W; Oppenheimer, Rebecca; Poyneer, Lisa; Rajan, Abhijith; Rantakyrö, Fredrik T; Ruffio, Jean-Baptiste; Sadakuni, Naru; Saddlemyer, Leslie; Schneider, Adam C; Sivaramakrishnan, Anand; Soummer, Remi; Thomas, Sandrine; Vasisht, Gautam; Vega, David; Wallace, J Kent; Ward-Duong, Kimberly; Wiktorowicz, Sloane J; Wolff, Schuyler G

    2015-01-01

    We present $H$-band observations of $\\beta$ Pic with the Gemini Planet Imager's (GPI's) polarimetry mode that reveal the debris disk between ~0.3" (~6 AU) and ~1.7" (~33 AU), while simultaneously detecting $\\beta$ Pic $b$. The polarized disk image was fit with a dust density model combined with a Henyey-Greenstein scattering phase function. The best fit model indicates a disk inclined to the line of sight ($\\phi=85.27{\\deg}^{+0.26}_{-0.19}$) with a position angle $\\theta_{PA}=30.35{\\deg}^{+0.29}_{-0.28}$ (slightly offset from the main outer disk, $\\theta_{PA}\\approx29{\\deg}$), that extends from an inner disk radius of $23.6^{+0.9}_{-0.6}$ AU to well outside GPI's field of view. In addition, we present an updated orbit for $\\beta$ Pic $b$ based on new astrometric measurements taken in GPI's spectroscopic mode spanning 14 months. The planet has a semi-major axis of $a=9.2^{+1.5}_{-0.4}$AU, with an eccentricity $e\\leq 0.26$. The position angle of the ascending node is $\\Omega=31.75{\\deg}\\pm0.15$, offset from bot...

  4. Analysis distribution of galactic cosmic rays particle energy with polar orbit satellite for Geant4 application

    International Nuclear Information System (INIS)

    Galactic Cosmic Rays (GCR) are photon waves originating from astrophysical sources which traverse through the interstellar/interplanetary medium and reaching the terrestrial atmosphere. The energies of Galactic Cosmic Ray particles up to and exceeding 1012 eV, and this spectrum are peaked around 1 GeV. The National Aeronautics and Space Administration (NASA) provide satellite mission for monitoring the energy GCR particles in polar orbit, so-called the ACE and OMNI. In this paper, we analyze results from measurement error of GCR sensor. The error result is obtained by comparing the measurements from GCR sensor with ground-based neutron monitors at Bartol University. The measurements were taken for two periods during a Solar Particle Event (SPE) maximum on 14 July 2000 and 28 October 2003. The largest value of measurement error from GCR sensor in this study is OMNI satellites. After the error results were obtained, they were applied into Geant4 simulation. This simulation shows the shape of particle energy distribution of GCR sensors. The simulation has been tested and can be operated very well under Linux based platform.

  5. Limb Correction of Polar-Orbiting Imagery for the Improved Interpretation of RGB Composites

    Science.gov (United States)

    Jedlovec, Gary J.; Elmer, Nicholas

    2016-01-01

    Red-Green-Blue (RGB) composite imagery combines information from several spectral channels into one image to aid in the operational analysis of atmospheric processes. However, infrared channels are adversely affected by the limb effect, the result of an increase in optical path length of the absorbing atmosphere between the satellite and the earth as viewing zenith angle increases. This paper reviews a newly developed technique to quickly correct for limb effects in both clear and cloudy regions using latitudinally and seasonally varying limb correction coefficients for real-time applications. These limb correction coefficients account for the increase in optical path length in order to produce limb-corrected RGB composites. The improved utility of a limb-corrected Air Mass RGB composite from the application of this approach is demonstrated using Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. However, the limb correction can be applied to any polar-orbiting sensor infrared channels, provided the proper limb correction coefficients are calculated. Corrected RGB composites provide multiple advantages over uncorrected RGB composites, including increased confidence in the interpretation of RGB features, improved situational awareness for operational forecasters, and the ability to use RGB composites from multiple sensors jointly to increase the temporal frequency of observations.

  6. Bonding, Backbonding, and Spin-Polarized Molecular Orbitals: Basis for Magnetism and Semiconducting Transport in V[TCNE]x~;;2

    OpenAIRE

    Kortright, Jeffrey B.

    2008-01-01

    X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (MCD) at the V L2,3 and C and N K edges reveal bonding/backbonding interactions in films of the 400 K magnetic semiconductor V[TCNE]x~;;2. In V spectra, dxy-like orbitals are modeled assuming V2+ in an octahedral ligand field, while dz2 and dx2-y2 orbitals involved in strong covalent bonding cannot be modeled by atomic calculations. C and N MCD, and differences in XAS from neutral TCNE molecules, reveal spin-polarized molec...

  7. Spin Polarization and Andreev Conductance through a Diluted Magnetic Semiconductor Quantum Wire with Spin-Orbit Interaction

    Institute of Scientific and Technical Information of China (English)

    LI Yu-Xian

    2008-01-01

    Spin-dependent Andreev reflection and spin polarization through a diluted magnetic semiconductor quantum wire coupled to normal metallic and superconductor electrodes are investigated using scattering theory. When the spin-orbit coupling is considered, more Andreev conductance steps appear at the same Fermi energy. Magnetic semiconductor quantum wire separates the spin-up and spin-down electrons. The Fermi energy, at which different-spin-state electrons begin to separate, becomes lower due to the effect of the spin-orbit interaction. The spin filter effect can be measured more easily by investigating the Andreev conductance than by investigating the normal conductance.

  8. Dual-polarization and dual-mode orbital angular momentum radio vortex beam generated by using reflective metasurface

    Science.gov (United States)

    Yu, Shixing; Li, Long; Shi, Guangming

    2016-08-01

    A metasurface, which is composed of printed cross-dipole elements with different arm lengths, is designed, fabricated, and experimentally demonstrated to generate orbital angular momentum (OAM) vortex waves of dual polarizations and dual modes in the radio frequency domain simultaneously. The prototype of a practical metasurface is fabricated and measured to validate the results of theoretical analysis and design at 5.8 GHz. Numerical and experimental results verify that vortex waves with dual OAM modes and dual polarizations can be flexibly generated by using a reflective metasurface. The proposed method paves a way to generate diverse OAM vortex waves for radio frequency and microwave wireless communication applications.

  9. Toward a Unified View of the Moon's Polar Volatiles from the Lunar Reconnaissance Orbiter

    Science.gov (United States)

    Hayne, Paul

    2016-04-01

    Although the scientific basis for the possibility of water and other volatiles in the cold traps of the lunar polar regions was developed in the 1960's and '70's [1,2], only recently have the data become available to test the theories in detail. Furthermore, comparisons with other planetary bodies, particularly Mercury, have revealed surprising differences that may point to inconsistencies or holes in our understanding of the basic processes involving volatiles on airless bodies [3]. Addressing these gaps in understanding is critical to the future exploration of the Moon, for which water is an important scientific and engineering resource [4]. Launched in 2009, NASA's Lunar Reconnaissance Orbiter (LRO) has been acquiring data from lunar orbit for more than six years. All seven of the remote sensing instruments on the payload have now contributed significantly to advancing understanding of volatiles on the Moon. Here we present results from these investigations, and discuss attempts to synthesize the disparate information to create a self-consistent model for lunar volatiles. In addition to the LRO data, we must take into account results from earlier missions [5,6], ground-based telescopes [7], and sample analyses [8]. The results from these inter-comparisons show that water is likely available in useful quantities, but key additional measurements may be required to resolve remaining uncertainties. [1] Watson, K., Murray, B. C., & Brown, H. (1961), J. Geophys. Res., 66(9), 3033-3045. [2] Arnold, J. R. (1979), J. Geophys. Res. (1978-2012), 84(B10), 5659-5668. [3] Paige, D. A., Siegler, M. A., Harmon, J. K., Neumann, G. A., Mazarico, E. M., Smith, D. E., ... & Solomon, S. C. (2013), Science, 339(6117), 300-303. [4] Hayne, P. O., et al. (2014), Keck Inst. Space Studies Report. [5] Nozette, S., Lichtenberg, C. L., Spudis, P., Bonner, R., Ort, W., Malaret, E., ... & Shoemaker, E. M. (1996), Science, 274(5292), 1495-1498. [6] Pieters, C. M., Goswami, J. N., Clark, R. N

  10. Out-of-plane spin polarization of edge currents in Chern insulator with Rashba spin-orbit interaction.

    Science.gov (United States)

    Chen, Tsung-Wei; Hsiao, Chin-Lun; Hu, Chong-Der

    2016-07-13

    We investigate the change in the non-zero Chern number and out-of-plane spin polarization of the edge currents in a honeycomb lattice with the Haldane-Rashba interaction. This interaction breaks the time-reversal symmetry due to the Haldane phase caused by a current loop at the site-I and site-II atoms, and also accounts for the Rashba-type spin-orbit interaction. The Rashba spin-orbit interaction increases the number of Dirac points and the band-touching phenomenon can be generated by tuning the on-site potential in the non-zero Haldane phase. By using the Pontryagin winding number and numerical Berry curvature methods, we find that the Chern number pattern is {+2, -1, 0} and {-2, +1, 0} for the positive and negative Haldane phase, respectively. A non-zero Chern number is called a Chern-insulating phase. We discovered that changes in both the Haldane phase and on-site potential leads to a change in the orientation of the bulk spin polarization of site-I and site-II atoms. Interestingly, in a ribbon with a zigzag edge, which naturally has site-I atoms at one outer edge and site-II atoms at the opposite outer edge, the spin polarization of the edge states approximately obeys the properties of bulk spin polarization regardless of the change in the Chern number. In addition, even when the Chern number changes from  +2 to  -1 (or  -2 to  +1), by tuning the strength of the on-site potential, the sign of the spin polarization of the edge states persists. This approximate bulk-edge correspondence of the spin polarization in the Haldane-Rashba system would play an important role in spintronics, because it enables us to control the orientation of the spin polarization in a single Chern-insulating phase. PMID:27195598

  11. Orbiting.

    OpenAIRE

    Halford, Sarah Juliette

    2013-01-01

    I always knew I was from another planet. Earth was my home, yes, I liked hamburgers and roller coasters, but there was still an orbit in me that seemed out of place. My imaginative orbit felt like it didn't to spin the "normal" way. As a performer I spent more time alienating myself and judging how different I felt, rather than owning the creative space I lived in and applying it to my craft. My past three years at UC San Diego have been the perfect atmosphere for my artist self. I have been ...

  12. KEPLER-63b: A GIANT PLANET IN A POLAR ORBIT AROUND A YOUNG SUN-LIKE STAR

    Energy Technology Data Exchange (ETDEWEB)

    Sanchis-Ojeda, Roberto; Winn, Joshua N.; Albrecht, Simon [Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Marcy, Geoffrey W.; Isaacson, Howard [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Johnson, John Asher [Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Torres, Guillermo; Carter, Joshua A.; Dawson, Rebekah I.; Geary, John C. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Campante, Tiago L.; Chaplin, William J.; Davies, Guy R. [School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Lund, Mikkel N. [Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Buchhave, Lars A. [Niels Bohr Institute, University of Copenhagen, Juliane Maries vej 30, DK-2100 Copenhagen (Denmark); Everett, Mark E. [National Optical Astronomy Observatory, 950 N. Cherry Ave, Tucson, AZ 85719 (United States); Fischer, Debra A. [Astronomy Department, Yale University, New Haven, CT (United States); Gilliland, Ronald L. [Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Horch, Elliott P. [Southern Connecticut State University, New Haven, CT 06515 (United States); and others

    2013-09-20

    We present the discovery and characterization of a giant planet orbiting the young Sun-like star Kepler-63 (KOI-63, m{sub Kp} = 11.6, T{sub eff} = 5576 K, M{sub *} = 0.98 M{sub ☉}). The planet transits every 9.43 days, with apparent depth variations and brightening anomalies caused by large starspots. The planet's radius is 6.1 ± 0.2 R{sub ⊕}, based on the transit light curve and the estimated stellar parameters. The planet's mass could not be measured with the existing radial-velocity data, due to the high level of stellar activity, but if we assume a circular orbit, then we can place a rough upper bound of 120 M{sub ⊕} (3σ). The host star has a high obliquity (ψ = 104°), based on the Rossiter-McLaughlin effect and an analysis of starspot-crossing events. This result is valuable because almost all previous obliquity measurements are for stars with more massive planets and shorter-period orbits. In addition, the polar orbit of the planet combined with an analysis of spot-crossing events reveals a large and persistent polar starspot. Such spots have previously been inferred using Doppler tomography, and predicted in simulations of magnetic activity of young Sun-like stars.

  13. Spin polarized bound states in the continuum in open Aharonov-Bohm rings with the Rashba spin-orbit interaction.

    Science.gov (United States)

    Bulgakov, Evgeny N; Sadreev, Almas F

    2016-07-01

    We consider the trapping of electrons with a definite spin polarization by bound states in the continuum (BSC) in the open Aharonov-Bohm rings in the presence of the Rashba spin-orbit interaction (RSOI). Neglecting the Zeeman term we show the existence of BSCs in the one-dimensional ring when the eigenstates of the closed ring are doubly degenerate. With account of the Zeeman term BSCs occur only at the points of threefold degeneracy. The BSCs are found in the parametric space of flux and RSOI strength in close pairs with opposite spin polarization. Thereby the spin polarization of electrons transmitted through the ring can be altered by minor variation of magnetic or electric field at the vicinity of these pairs. Numerical simulations of the two-dimensional open ring show similar results for the BSCs. Encircling the BSC points in the parametric space of the flux and the RSOI constant gives rise to a geometric phase. PMID:27165662

  14. The Operational Utility of Space Environmental Measurements From Polar-Orbiting, Sun-Synchronous Satellites in AFWA Models and Applications

    Science.gov (United States)

    Citrone, P. J.; Bonadonna, M. F.; Cade, T.; Nobis, T. E.; Denig, W. F.

    2005-12-01

    Satellite-based measurements of the space environment provide vital data inputs to advanced space weather models and applications used by the Air Force Weather Agency (AFWA) to generate mission-tailored space weather intelligence in support of U.S. military operations. Since the 1970's, the Defense Meteorological Satellite Program (DMSP) has provided in-situ measurements of the topside ionosphere and of the differential energy flux of precipitating electrons and ions into the auroral and polar regions. Recently, DMSP has deployed a new class of ultraviolet remote sensors which offer opportunities for improved space environmental monitoring. The DMSP polar-orbiting, sun-synchronous satellite measurements provide critical data inputs for current and future AFWA space weather models that specify and forecast the global thermosphere, ionosphere, and magnetosphere. The AFWA Space Weather Technology Branch is pursuing an ongoing effort to transition to operations advanced research technologies associated with space environmental forecasting, to include related software applications used by AFWA to generate mission-tailored visualization products that depict space weather impacts on military systems. The Space Environmental Sensor Suite (SESS) on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) will offer improved capabilities in terms of characterization and timeliness for space environmental data required by AFWA to meet new and emerging Department of Defense space weather operational requirements.

  15. Research Update: Orbital polarization in LaNiO{sub 3}-based heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Disa, Ankit S., E-mail: ankit.disa@yale.edu; Walker, F. J. [Center for Research on Interface Structures and Phenomena and Department of Applied Physics, Yale University, New Haven, Connecticut 06511 (United States); Ismail-Beigi, Sohrab; Ahn, Charles H. [Center for Research on Interface Structures and Phenomena and Department of Applied Physics, Yale University, New Haven, Connecticut 06511 (United States); Department of Physics and Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511 (United States)

    2015-06-01

    The relative energies and occupancies of valence orbital states can dramatically influence collective electronic and magnetic phenomena in correlated transition metal oxide systems. We review the current state of research on the modification and control of these orbital properties in rare-earth nickelates, especially LaNiO{sub 3}, a model degenerate d orbital system where significant recent progress has been made. Theoretical and experimental results on thin films and heterostructures are described, including the influence of electronic correlation effects. We highlight the latest approaches to achieving non-degenerate bands and discuss the outlook and applicability of this body of knowledge to other correlated metal oxide systems.

  16. Research Update: Orbital polarization in LaNiO3-based heterostructures

    International Nuclear Information System (INIS)

    The relative energies and occupancies of valence orbital states can dramatically influence collective electronic and magnetic phenomena in correlated transition metal oxide systems. We review the current state of research on the modification and control of these orbital properties in rare-earth nickelates, especially LaNiO3, a model degenerate d orbital system where significant recent progress has been made. Theoretical and experimental results on thin films and heterostructures are described, including the influence of electronic correlation effects. We highlight the latest approaches to achieving non-degenerate bands and discuss the outlook and applicability of this body of knowledge to other correlated metal oxide systems

  17. Chaos and its control in the pitch motion of an asymmetric magnetic spacecraft in polar elliptic orbit

    International Nuclear Information System (INIS)

    We study the pitch attitude dynamics of an asymmetric magnetic spacecraft in a polar almost circular orbit under the influence of a gravity gradient torque. The spacecraft is perturbed by the small eccentricity of the elliptic orbit and by a small magnetic torque generated by the interaction between the Earth's magnetic field and the magnetic moment of the spacecraft. Under both perturbations, we show that the pitch motion exhibits heteroclinic chaotic behavior by means of the Melnikov method. Numerical methods applied to simulations of the pitch motion also confirm the chaotic character of the spacecraft attitude dynamics. Finally, a linear time-delay feedback method for controlling chaos is applied to the governing equations of the spacecraft pitch motion in order to remove the chaotic character of initially irregular attitude motions and transform them into periodic ones.

  18. Field-assisted spin-polarized electron transport through a single quantum well with spin-orbit coupling

    International Nuclear Information System (INIS)

    We have investigated theoretically the field-driven electron transport through a single-quantum-well semiconductor heterostructure with spin—orbit coupling. The splitting of the asymmetric Fano-type resonance peaks due to the Dresselhaus spin—orbit coupling is found to be highly sensitive to the direction of the incident electron. The splitting of the Fano-type resonance induces the spin-polarization dependent electron current. The location and the line shape of the Fano-type resonance can be controlled by adjusting the energy and the direction of the incident electron, the oscillation frequency, and the amplitude of the external field. These interesting features may be used to devise tunable spin filters and realize pure spin transmission currents. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  19. Space environment monitoring by low-altitude operational satellites

    International Nuclear Information System (INIS)

    The primary task of the Defense Meteorological Satellite Program (DMSP) is the acquisition of meteorological data in the visual and infrared spectral regions. The Air Weather Service operates two satellites in low-altitude, sun-synchronous, polar orbits at 850 km altitude, 98.7 deg inclination, 101.5 minute period and dawn-dusk or noon-midnight equatorial crossing times. Special DMSP sensors of interest to the space science community are the precipitating electron spectrometer, the terrestrial noise receiver, and the topside ionosphere plasma monitor. Data from low-altitude, meteorological satellites can be used to build empirical models of precipitating electron characteristics of the auroral zone and polar cap. The Tiros-NOAA satellite program complements the DMSP program. The orbital elements are the same as DMSP's, except for the times of equatorial crossing, and the tilt of the orbital plane. The Tiros-NOAA program meets the civilian community's needs for meteorological data as the DMSP program does for the military

  20. Angular momentum of non-paraxial light beam: Dependence of orbital angular momentum on polarization

    OpenAIRE

    Li, Chun-Fang

    2009-01-01

    It is shown that the momentum density of free electromagnetic field splits into two parts. One has no contribution to the net momentum due to the transversality condition. The other yields all the momentum. The angular momentum that is associated with the former part is spin, and the angular momentum that is associated with the latter part is orbital angular momentum. Expressions for the spin and orbital angular momentum are given in terms of the electric vector in reciprocal space. The spin ...

  1. Experimental generation and characterization of single-photon hybrid ququarts based on polarization and orbital angular momentum encoding

    International Nuclear Information System (INIS)

    High-dimensional quantum states, or qudits, represent a promising resource in the quantum information field. Here we present the experimental generation of four-dimensional quantum states, or ququarts, encoded in the polarization and orbital angular momentum of a single photon. Our technique, based on the q-plate device, allows the ququart to be prepared and measured in all five mutually unbiased bases. We report the reconstruction of the four-dimensional density matrix through the tomographic procedure for different ququart states.

  2. All-electrical production of spin-polarized currents in carbon nanotubes: Rashba spin-orbit interaction

    Science.gov (United States)

    Santos, Hernán; Latgé, A.; Alvarellos, J. E.; Chico, Leonor

    2016-04-01

    We study the effect of the Rashba spin-orbit interaction in the quantum transport of carbon nanotubes with arbitrary chiralities. For certain spin directions, we find a strong spin-polarized electrical current that depends on the diameter of the tube, the length of the Rashba region, and on the tube chirality. Predictions for the spin-dependent conductances are presented for different families of achiral and chiral tubes. We have found that different symmetries acting on spatial and spin variables have to be considered in order to explain the relations between spin-resolved conductances in carbon nanotubes. These symmetries are more general than those employed in planar graphene systems. Our results indicate the possibility of having stable spin-polarized electrical currents in absence of external magnetic fields or magnetic impurities in carbon nanotubes.

  3. Conductance and spin polarization for a quantum wire with the competition of Rashba and Dresselhaus spin-orbit coupling

    International Nuclear Information System (INIS)

    We investigate theoretically the spin transport of a quantum wire (QW) with weak Rashba and Dresselhaus spin-orbit coupling (SOC) nonadiabatically connected to two normal leads. Using scattering matrix method and Landauer-Buettiker formula within effective free-electron approximation, we have calculated spin-dependent conductances G↑ and G↓, total conductance G and spin polarization Pz for a hard-wall potential confined QW. It is demonstrated that, the SOCs induce the splitting of G↑ and G↓ and form spin polarization Pz. Moreover, the conductances present quantized plateaus, the plateaus and Pz show oscillation structures near the subband edges. Furthermore, with the increase of QW width a strong spin polarization (Pz∼1) gradually becomes weak, which can be used to realize a spin filter. When the two SOCs coexist, the total conductance presents an isotropy transport due to the Rashba and Dresselhaus Hamiltonians being fixed, and the alteration of two SOCs strength ratio changes the sign of spin polarization. This may provide a way of realizing the expression of unit information by tuning gate voltage.

  4. Manipulation of orbital occupancy by ferroelectric polarization in LaNiO{sub 3}/BaTiO{sub 3−δ} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Peng, J. J.; Song, C., E-mail: songcheng@mail.tsinghua.edu.cn; Cui, B.; Li, F.; Mao, H. J.; Wang, G. Y.; Pan, F., E-mail: panf@mail.tsinghua.edu.cn [Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2015-11-02

    We investigate the control of orbital occupancy by ferroelectric polarization in LaNiO{sub 3}/BaTiO{sub 3−δ} heterostructures. It is achieved by the ferroelectric displacement of Ti ions polarized downward (upward) to form (break) Ni–O–Ti covalent bonding at the interface, accompanied by charge transfer between them and the modulation of the conductivity of ultrathin LaNiO{sub 3}. This electrically switchable and bi-direction control of orbital polarization in LaNiO{sub 3} is up to 25%, different from the manipulation by epitaxial strain or quantum confinement. Our finding opens a window for electrical control of orbital polarization at an oxide interface.

  5. Early On-Orbit Performance of the Visible Infrared Imaging Radiometer Suite Onboard the Suomi National Polar-Orbiting Partnership (S-NPP) Satellite

    Science.gov (United States)

    Cao, Changyong; DeLuccia, Frank J.; Xiong, Xiaoxiong; Wolfe, Robert; Weng, Fuzhong

    2014-01-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) is one of the key environmental remote-sensing instruments onboard the Suomi National Polar-Orbiting Partnership spacecraft, which was successfully launched on October 28, 2011 from the Vandenberg Air Force Base, California. Following a series of spacecraft and sensor activation operations, the VIIRS nadir door was opened on November 21, 2011. The first VIIRS image acquired signifies a new generation of operational moderate resolution-imaging capabilities following the legacy of the advanced very high-resolution radiometer series on NOAA satellites and Terra and Aqua Moderate-Resolution Imaging Spectroradiometer for NASA's Earth Observing system. VIIRS provides significant enhancements to the operational environmental monitoring and numerical weather forecasting, with 22 imaging and radiometric bands covering wavelengths from 0.41 to 12.5 microns, providing the sensor data records for 23 environmental data records including aerosol, cloud properties, fire, albedo, snow and ice, vegetation, sea surface temperature, ocean color, and nigh-time visible-light-related applications. Preliminary results from the on-orbit verification in the postlaunch check-out and intensive calibration and validation have shown that VIIRS is performing well and producing high-quality images. This paper provides an overview of the onorbit performance of VIIRS, the calibration/validation (cal/val) activities and methodologies used. It presents an assessment of the sensor initial on-orbit calibration and performance based on the efforts from the VIIRS-SDR team. Known anomalies, issues, and future calibration efforts, including the long-term monitoring, and intercalibration are also discussed.

  6. On the Orbital Period of the Intermediate Polar 1WGA J1958.2+3232

    CERN Document Server

    Zharikov, S V; Echevarria, J; Zharikov, Sergei V.; Tovmassian, Gaghik H.; Echevarria, Juan

    2002-01-01

    Recently, Norton et al. 2002, on the basis of multiwavelength photometry of 1WGA J1958.2+3232, argued that the -1 day alias of the strongest peak in the power spectrum is the true orbital period of the system, casting doubts on the period estimated by Zharikov et al. 2001. We re-analyzed this system using our photometric and spectroscopic data along with the data kindly provided by Andy Norton and confirm our previous finding. After refining our analysis we find that the true orbital period of this binary system is 4.35h.

  7. Bands, bonds, and polarizations in nitrides - from electronic orbitals to electronic devices

    International Nuclear Information System (INIS)

    A key property of the nitrides is the fact that they posses large spontaneous and piezoelectric polarization fields that allow a significant tailoring of the carrier dynamics and optical properties of nitride devices. In this paper, based on first-principle calculations of structural and electronic properties of bulk nitrides and their heterostructure, we investigate the potential of this novel material class for modern device applications by performing self-consistent Monte Carlo simulations. Our studies reveal that the nitride based electronic devices have characteristics that predispose them for high power and high frequency applications. We demonstrate also that transistor characteristics are favourably influenced by the internal polarization induced electric field. (author)

  8. 我国极轨气象卫星的发展%Development of China Polar Orbiting Meterological Satellite

    Institute of Scientific and Technical Information of China (English)

    李叶飞; 曹琼; 杨勇; 董瑶海

    2012-01-01

    The present statement of the polar orbiting meteorological satellite in China was introduced in this paper. The scheme of earth observation net composed by FY-3 morning satellite, afternoon satellite and raining detecting satellite was proposed. The main performances of the major instruments for the three satellites were given out. The development trend of the polar orbiting meteorological satellite such as the multi-payload observation, all- weather detection implementing with microwave band, improving spectrum resolution, improving the instrument sensibility and calibration precision, developing radio (GPS) occultation detection, and developing active remote sensing were discussed. The suggestions for China polar orbiting meteorological satellite development, which were earth integrated observation for meteorological satellite, high space resolution, high time resolution, high spectrum resolution, high radiation accuracy and global, all-weather and multi-band observation for remote sensing technology, active and passive detection integrating, high precision and quantitative for remote sensing application, and special satellite or small satellite array, were put forward. The key technologies to realize China polar orbiting meteorological satellite such as the coupling suppression of the rotational part and solar array, attitude control with high directional precision and high stability, data transmit with high data ratio, influence analysis of flutter on high spectrum imaging quality and vibration damping, high accuracy ground calibration and in-orbit calibration of active microwave, visual, infrared and ultraviolet band were also discussed.%介绍了我国极轨气象卫星的现况。提出了由风云三号(FY-3)上午星、下午星和降水测量卫星组成的我国极轨气象卫星对地观测网构想,给出了三种卫星的主要仪器性能指标。讨论了多载荷综合观测,利用微波波段实现全天候探测,提高光谱分辨率,提

  9. Influence of quantum confinement and strain on orbital polarization of four-layer LaNiO3 superlattices: A DFT+DMFT study

    Science.gov (United States)

    Park, Hyowon; Millis, Andrew J.; Marianetti, Chris A.

    2016-06-01

    Atomically precise superlattices involving transition-metal oxides provide a unique opportunity to engineer correlated electron physics using strain (modulated by choice of substrate) and quantum confinement (controlled by layer thickness). Here we use the combination of density-functional theory and dynamical mean-field theory (DFT+DMFT) to study Ni Egd -orbital polarization in strained LaNiO3/LaAlO3 superlattices consisting of four layers of nominally metallic NiO2 and four layers of insulating AlO2 separated by LaO layers. The layer-resolved orbital polarization is calculated as a function of strain and analyzed in terms of structural, quantum confinement, and correlation effects. The effect of strain is determined from the dependence of the results on the Ni-O bond-length ratio and the octahedral rotation angles, quantum confinement is studied by comparison to bulk calculations with similar degrees of strain, and correlation effects are inferred by varying interaction parameters within our DFT+DMFT calculations. The calculated dependence of orbital polarization on strain in superlattices is qualitatively consistent with recent x-ray-absorption spectroscopy and resonant reflectometry data. However, interesting differences of detail are found between theory and experiment. Under tensile strain, the two inequivalent Ni ions display orbital polarization similar to that calculated for strained bulk LaNiO3 and observed in experiment. Compressive strain produces a larger dependence of orbital polarization on Ni position, and even the inner Ni layer exhibits orbital polarization different from that calculated for strained bulk LaNiO3.

  10. Spin-orbit-coupling-induced Fulde-Ferrell-Larkin-Ovchinnikov-like Cooper pairing and skyrmion-like polarization textures in optical lattices

    OpenAIRE

    Işkın, Menderes

    2013-01-01

    PHYSICAL REVIEW A 88, 013631 (2013) Spin-orbit-coupling-induced Fulde-Ferrell-Larkin-Ovchinnikov-like Cooper pairing and skyrmion-like polarization textures in optical lattices M. Iskin Department of Physics, Koc¸ University, Rumelifeneri Yolu, 34450 Sarıyer, Istanbul, Turkey (Received 8 April 2013; published 25 July 2013) We study the interplay between the Zeeman field and spin-orbit coupling (SOC) in harmonically trapped Fermi gases loaded into a two-dimensional single-...

  11. Review of a relativity and geodesy mission with counter-orbiting polar satellites

    International Nuclear Information System (INIS)

    A new test of general relativity, capable of measuring the Lense-Thirring precession on a satellite orbit was proposed in 1974. We have recently realized that the remarkable geophysical output of this experiment can be enriched by allowing the point of encounter between the two satellites to progress from the poles to the equator during the course of the mission. There is reason to believe that by performing the experiment in this mode, all tesseral harmonics up to about 60th order could be separated and determined to accuracies up to three orders of magnitude better than current knowledge, and still obtain a 1% Lense-Thirring measurement. (orig.)

  12. Sunlight effects on the 3D polar current system determined from low Earth orbit measurements

    DEFF Research Database (Denmark)

    Laundal, Karl M.; Finlay, Chris; Olsen, Nils

    2016-01-01

    Interaction between the solar wind and the Earth’s magnetosphere is associated with large-scale currents in the ionosphere at polar latitudes that flow along magnetic field lines (Birkeland currents) and horizontally. These current systems are tightly linked, but their global behaviors are rarely...... show that the Birkeland currents vary with the conductivity, which depends most strongly on solar EUV emissions on the dayside and on particle precipitation at pre-midnight magnetic local times. In sunlight, the horizontal equivalent current flows in two cells, resembling an opposite ionospheric...

  13. Two-Dimensional Pnictogen Honeycomb Lattice: Structure, On-Site Spin-Orbit Coupling and Spin Polarization.

    Science.gov (United States)

    Lee, Jason; Tian, Wen-Chuan; Wang, Wei-Liang; Yao, Dao-Xin

    2015-01-01

    Because of its novel physical properties, two-dimensional materials have attracted great attention. From first-principle calculations and vibration frequencies analysis, we predict a new family of two-dimensional materials based on the idea of octet stability: honeycomb lattices of pnictogens (N, P, As, Sb, Bi). The buckled structures of materials come from the sp(3) hybridization. These materials have indirect band gap ranging from 0.43 eV to 3.7 eV. From the analysis of projected density of states, we argue that the s and p orbitals together are sufficient to describe the electronic structure under tight-binding model, and the tight-binding parameters are obtained by fitting the band structures to first-principle results. Surprisingly large on-site spin-orbit coupling is found for all the pnictogen lattices except nitrogen. Investigation on the electronic structures of both zigzag and armchair nanoribbons reveals the possible existence of spin-polarized ferromagnetic edge states in some cases, which are rare in one-dimensional systems. These edge states and magnetism may exist under the condition of high vacuum and low temperature. This new family of materials would have promising applications in electronics, optics, sensors, and solar cells. PMID:26122870

  14. A Dual Polarization, Active, Microstrip Antenna for an Orbital Imaging Radar System Operating at L-Band

    Science.gov (United States)

    Kelly, Kenneth C.; Huang, John

    2000-01-01

    A highly successful Earth orbiting synthetic antenna aperture radar (SAR) system, known as the SIR-C mission, was carried into orbit in 1994 on a U.S. Shuttle (Space Transportation System) mission. The radar system was mounted in the cargo bay with no need to fold, or in any other way reduce the size of the antennas for launch. Weight and size were not limited for the L-Band, C-Band, and X-Band radar systems of the SIR-C radar imaging mission; the set of antennas weighed 10,500 kg, the L-Band antenna having the major share of the weight. This paper treats designing an L-Band antenna functionally similar to that used for SIR-C, but at a fraction of the cost and at a weight in the order of 250 kg. Further, the antenna must be folded to fit into the small payload shroud of low cost booster rocket systems. Over 31 square meters of antenna area is required. This low weight, foldable, electronic scanning antenna is for the proposed LightSAR radar system which is to be placed in Earth orbit on a small, dedicated space craft at the lowest possible cost for an efficient L- Band radar imaging system. This LightSAR spacecraft radar is to be continuously available for at least five operational years, and have the ability to map or repeat-map any area on earth within a few days of any request. A microstrip patch array, with microstrip transmission lines heavily employed in the aperture and in the corporate feed network, was chosen as the low cost approach for this active dual-polarization, 80 MHz (6.4%) bandwidth antenna design.

  15. Transition of Suomi National Polar-Orbiting Partnership (S-NPP) Data Products for Operational Weather Forecasting Applications

    Science.gov (United States)

    Smith, M. R.; Fuell, K.; Molthan, A.; Jedlovec, G.

    2012-12-01

    The launch of the Suomi National Polar-Orbiting Partnership (S-NPP) satellite provides new and exciting opportunities for the application of remotely sensed data products in operational weather forecasting environments. The NASA Short-term Prediction Research and Transition (SPoRT) Center in Huntsville, Alabama is a NASA and NOAA-funded project to assist with the transition of experimental and research products to the operational weather community through partnership with NOAA/National Weather Service Weather Forecast Offices (NWS WFOs) throughout the United States. This presentation will provide the S-NPP community with an update on current and future SPoRT projects related to the dissemination of S-NPP derived data to NWS WFOs and highlight unique applications and value of data from the Visible Infrared Imaging Radiometer Suite (VIIRS), specifically applications of high resolution visible and infrared data, uses of the day-night (or near constant contrast) band, and multispectral composites. Other applications are envisioned through use of selected channels of the Cross-track Infrared Sounder (CrIS), the Advanced Technology Microwave Sounder (ATMS), and the Ozone Mapper Profiler Suite (OMPS). This presentation will also highlight opportunities for future collaboration with SPoRT and activities planned for participation in the NOAA Joint Polar Satellite Program (JPSS) Proving Ground.

  16. Spin polarization, orbital occupation and band gap opening in vanadium dioxide: The effect of screened Hartree-Fock exchange

    KAUST Repository

    Wang, Hao

    2014-07-01

    The metal-insulator transition of VO2 so far has evaded an accurate description by density functional theory. The screened hybrid functional of Heyd, Scuseria and Ernzerhof leads to reasonable solutions for both the low-temperature monoclinic and high-temperature rutile phases only if spin polarization is excluded from the calculations. We explore whether a satisfactory agreement with experiment can be achieved by tuning the fraction of Hartree Fock exchange (α) in the density functional. It is found that two branches of locally stable solutions exist for the rutile phase for 12.5%≤α≤20%. One is metallic and has the correct stability as compared to the monoclinic phase, the other is insulating with lower energy than the metallic branch. We discuss these observations based on the V 3d orbital occupations and conclude that α=10% is the best possible choice for spin-polarized VO2 calculations. © 2014 Elsevier B.V. All rights reserved.

  17. Giant Optical Polarization Rotation Induced by Spin-Orbit Coupling in Polarons

    Science.gov (United States)

    Casals, Blai; Cichelero, Rafael; García Fernández, Pablo; Junquera, Javier; Pesquera, David; Campoy-Quiles, Mariano; Infante, Ingrid C.; Sánchez, Florencio; Fontcuberta, Josep; Herranz, Gervasi

    2016-07-01

    We have uncovered a giant gyrotropic magneto-optical response for doped ferromagnetic manganite La2 /3Ca1 /3MnO3 around the near room-temperature paramagnetic-to-ferromagnetic transition. At odds with current wisdom, where this response is usually assumed to be fundamentally fixed by the electronic band structure, we point to the presence of small polarons as the driving force for this unexpected phenomenon. We explain the observed properties by the intricate interplay of mobility, Jahn-Teller effect, and spin-orbit coupling of small polarons. As magnetic polarons are ubiquitously inherent to many strongly correlated systems, our results provide an original, general pathway towards the generation of magnetic-responsive gigantic gyrotropic responses that may open novel avenues for magnetoelectric coupling beyond the conventional modulation of magnetization.

  18. WASP-121 b: a hot Jupiter in a polar orbit and close to tidal disruption

    CERN Document Server

    Delrez, L; Almenara, J -M; Anderson, D R; Collier-Cameron, A; Díaz, R F; Gillon, M; Hellier, C; Jehin, E; Lendl, M; Maxted, P F L; Neveu-VanMalle, M; Pepe, F; Pollacco, D; Queloz, D; Ségransan, D; Smalley, B; Smith, A M S; Triaud, A H M J; Udry, S; Van Grootel, V; West, R G

    2015-01-01

    We present the discovery by the WASP-South survey, in close collaboration with the Euler and TRAPPIST telescopes, of WASP-121 b, a new remarkable short-period transiting hot Jupiter, whose planetary nature has been statistically validated by the PASTIS software. The planet has a mass of $1.183_{-0.062}^{+0.064}$ $M_{\\mathrm{Jup}}$, a radius of 1.865 $\\pm$ 0.044 $R_{\\mathrm{Jup}}$, and transits every $1.2749255_{-0.0000025}^{+0.0000020}$ days an active F6-type main-sequence star ($V$=10.4, $1.353_{-0.079}^{+0.080}$ $M_{\\odot}$, 1.458 $\\pm$ 0.030 $R_{\\odot}$, $T_{\\mathrm{eff}}$ = 6460 $\\pm$ 140 K). A notable property of WASP-121 b is that its orbital semi-major axis is only $\\sim$1.15 times larger than its Roche limit, which suggests that the planet might be close to tidal disruption. Furthermore, its large size and extreme irradiation ($\\sim$$7.1\\:10^{9}$ erg $\\mathrm{s}^{-1} \\mathrm{cm}^{-2}$) make it an excellent target for atmospheric studies via secondary eclipse observations. Using the TRAPPIST telescope,...

  19. Energetic particle environment in near-Earth orbit.

    Science.gov (United States)

    Klecker, B

    1996-01-01

    The hazard of exposure to high doses of ionizing radiation is one of the primary concerns of extended manned space missions and a continuous threat for the numerous spacecraft in operation today. In the near-Earth environment the main sources of radiation are solar energetic particles (SEP), galactic cosmic rays (GCR), and geomagnetically trapped particles, predominantly protons and electrons. The intensity of the SEP and GCR source depends primarily on the phase of the solar cycle. Due to the shielding effect of the Earth's magnetic field, the observed intensity of SEP and GCR particles in a near-Earth orbit will also depend on the orbital parameters altitude and inclination. The magnetospheric source strength depends also on these orbital parameters because they determine the frequency and location of radiation belt passes. In this paper an overview of the various sources of radiation in the near-Earth orbit will be given and first results obtained with the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) will be discussed. SAMPEX was launched on 3 July 1992 into a near polar (inclination 82 degrees) low altitude (510 x 675 km) orbit. The SAMPEX payload contains four separate instruments of high sensitivity covering the energy range 0.5 to several hundred MeV/nucleon for ions and 0.4 to 30 MeV for electrons. This low altitude polar orbit with zenith-oriented instrumentation provides a new opportunity for a systematic study of the near-Earth energetic particle environment. PMID:11540369

  20. Long orbital period pre-polars containing an early K-type donor stars. Bottleneck accretion mechanism in action

    CERN Document Server

    Tovmassian, G; Zharikov, S; Reichart, D E; Haislip, J B; Ivarsen, K M; LaCluyze, A P; Moore, J P; Miroshnichenko, A S

    2016-01-01

    We studied two objects identified as a Cataclysmic Variables (CVs) with periods exceeding the natural boundary for Roche lobe filling ZAMS secondary stars. We present observational results for V1082 Sgr with 20.82 h orbital period, an object that shows low luminosity state, when its flux is totally dominated by a chromospherically active K- star with no signs of ongoing accretion. Frequent accretion shut-offs, together with characteristics of emission lines in a high state, indicate that this binary system is probably detached and the accretion of matter on the magnetic white dwarf takes place through stellar wind from the active donor star via coupled magnetic fields. Its observational characteristics are surprisingly similar to V479 And, a 14.5 h binary system. They both have early K-type stars as a donor star. We argue, that similar to the shorter period pre-polars containing M-dwarfs, these are detached binaries with strong magnetic components. Their magnetic fields are coupled, allowing enhanced stellar ...

  1. Impact of interfacial scattering on the spin polarization of a metal/semiconductor/metal with Rashba spin–orbit coupling junction

    International Nuclear Information System (INIS)

    The conductance spectrum and the normalized spin polarization due to the spin-dependent conductance of a metal/semiconductor/metal with Rashba spin–orbit coupling junction are theoretically studied within a free electron approximation and a scattering method. The effect of the first and the second interfacial scattering potentials on the two quantities are considered, especially when both of the potential strengths are not equal. While the conductance is determined by the higher interfacial scattering potential, the spin polarization is determined by the second interfacial barrier potential of the junction

  2. Ionization of oriented targets by intense circularly polarized laser pulses: Imprints of orbital angular nodes in the two-dimensional momentum distribution

    DEFF Research Database (Denmark)

    Martiny, Christian; Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2010-01-01

    We solve the three-dimensional time-dependent Schrödinger equation for a few-cycle circularly polarized femtosecond laser pulse that interacts with an oriented target exemplified by an argon atom, initially in a 3px or 3py state. The photoelectron momentum distributions show distinct signatures of....... Furthermore, we show that ionization by a circularly polarized pulse completely maps out the angular nodal structure of the initial state, thus providing a potential tool for studying orbital symmetry in individual systems or during chemical reactions....

  3. Perfect tuning of spin-polarization in a ring-shaped multiple-quantum-dot nanostructure in the presence of Rashba spin–orbit coupling

    Energy Technology Data Exchange (ETDEWEB)

    Eslami, L., E-mail: Leslami@iust.ac.ir; Chaghari, Z.; Faizabadi, E.

    2013-09-02

    Spin-dependent electronic transport through an open multiple-quantum-dot ring threaded by a magnetic flux is theoretically investigated by using the single particle Green's function method. By introducing local Rashba spin–orbit interaction on an individual quantum dot and local magnetic moments on two of other quantum dots, we calculate the spin-polarization in the output lead. We find the spin-polarization can be tuned by manipulating magnetic moments, adjusting magnetic flux and setting the Rashba spin–orbit strength. It is also shown the system can operate as an efficient spin-inverter when the structure is adjusted properly. The analysis can be utilized in designing optimized nanodevices.

  4. Subband Structure of a Two-Dimensional Electron Gas Formed at the Polar Surface of the Strong Spin-Orbit Perovskite KTaO3

    Energy Technology Data Exchange (ETDEWEB)

    King, P.D.C.

    2012-03-01

    We demonstrate the formation of a two-dimensional electron gas (2DEG) at the (100) surface of the 5d transition-metal oxide KTaO{sub 3}. From angle-resolved photoemission, we find that quantum confinement lifts the orbital degeneracy of the bulk band structure and leads to a 2DEG composed of ladders of subband states of both light and heavy carriers. Despite the strong spin-orbit coupling, we find no experimental signatures of a Rashba spin splitting, which has important implications for the interpretation of transport measurements in both KTaO{sub 3}- and SrTiO{sub 3}-based 2DEGs. The polar nature of the KTaO{sub 3}(100) surface appears to help mediate formation of the 2DEG as compared to non-polar SrTiO{sub 3}(100).

  5. Estimation and Validation of Land Surface Temperatures from Chinese Second-Generation Polar-Orbit FY-3A VIRR Data

    Directory of Open Access Journals (Sweden)

    Bo-Hui Tang

    2015-03-01

    Full Text Available This work estimated and validated the land surface temperature (LST from thermal-infrared Channels 4 (10.8 µm and 5 (12.0 µm of the Visible and Infrared Radiometer (VIRR onboard the second-generation Chinese polar-orbiting FengYun-3A (FY-3A meteorological satellite. The LST, mean emissivity and atmospheric water vapor content (WVC were divided into several tractable sub-ranges with little overlap to improve the fitting accuracy. The experimental results showed that the root mean square errors (RMSEs were proportional to the viewing zenith angles (VZAs and WVC. The RMSEs were below 1.0 K for VZA sub-ranges less than 30° or for VZA sub-ranges less than 60° and WVC less than 3.5 g/cm2, provided that the land surface emissivities were known. A preliminary validation using independently simulated data showed that the estimated LSTs were quite consistent with the actual inputs, with a maximum RMSE below 1 K for all VZAs. An inter-comparison using the Moderate Resolution Imaging Spectroradiometer (MODIS-derived LST product MOD11_L2 showed that the minimum RMSE was 1.68 K for grass, and the maximum RMSE was 3.59 K for barren or sparsely vegetated surfaces. In situ measurements at the Hailar field site in northeastern China from October, 2013, to September, 2014, were used to validate the proposed method. The result showed that the RMSE between the LSTs calculated from the ground measurements and derived from the VIRR data was 1.82 K.

  6. Precision Orbit Determination for the Lunar Reconnaissance Orbiter

    Science.gov (United States)

    Lemoine, F. G.; Mazarico, E.; Rowlands, D. D.; Torrence, M. H.; McGarry, J. F.; Neumann, G. A.; Mao, D.; Smith, D. E.; Zuber, M. T.

    2010-05-01

    The Lunar Reconnaissance Orbiter (LRO) spacecraft was launched on June 18, 2009. In mid-September 2009, the spacecraft orbit was changed from its commissioning orbit (30 x 216 km polar) to a quasi-frozen polar orbit with an average altitude of 50km (+-15km). One of the goals of the LRO mission is to develop a new lunar reference frame to facilitate future exploration. Precision Orbit Determination is used to achieve the accuracy requirements, and to precisely geolocate the high-resolution datasets obtained by the LRO instruments. In addition to the tracking data most commonly used to determine spacecraft orbits in planetary missions (radiometric Range and Doppler), LRO benefits from two other types of orbital constraints, both enabled by the Lunar Orbiter Laser Altimeter (LOLA) instrument. The altimetric data collected as the instrument's primary purpose can be used to derive constraints on the orbit geometry at the times of laser groundtrack intersections (crossovers). The multi-beam configuration and high firing-rate of LOLA further improves the strength of these crossovers, compared to what was possible with the MOLA instrument onboard Mars Global Surveyor (MGS). Furthermore, one-way laser ranges (LR) between Earth International Laser Ranging Service (ILRS) stations and the spacecraft are made possible by the addition of a small telescope mounted on the spacecraft high-gain antenna. The photons received from Earth are transmitted to one LOLA detector by a fiber optics bundle. Thanks to the accuracy of the LOLA timing system, the precision of 5-s LR normal points is below 10cm. We present the first results of the Precision Orbit Determination (POD) of LRO through the commissioning and nominal phases of the mission. Orbit quality is discussed, and various gravity fields are evaluated with the new (independent) LRO radio tracking data. The altimetric crossovers are used as an independent data type to evaluate the quality of the orbits. The contribution of the LR

  7. Remotely sensed soil temperatures beneath snow-free skin-surface using thermal observations from tandem polar-orbiting satellites: An analytical three-time-scale model

    DEFF Research Database (Denmark)

    Zhan, Wenfeng; Zhou, Ji; Ju, Weimin;

    2014-01-01

    and soil temperatures. Polar-orbiting satellite data from MODIS are used to show the model's capability. The results demonstrate that soil temperatures with a spatial resolution of 1km under snow-free conditions can be generated at any time of a clear-sky day. Validation is performed by using a......Subsurface soil temperature is a key variable of land surface processes and not only responds to but also modulates the interactions of energy fluxes at the Earth's surface. Thermal remote sensing has traditionally been regarded as incapable of detecting the soil temperature beneath the skin...

  8. Spin-resolved polarized transport through a quasi one-dimensional mesoscopic quantum ring-shaped conductor with local Rashba spin-orbit interaction

    Energy Technology Data Exchange (ETDEWEB)

    Liu, P., E-mail: pliu@jit.edu.cn [Basic Department, Jinling Institute of Technology, Nanjing 211169 (China); Liu, Y. [Physics Department, Lehigh University, Bethlehem, PA 18015 (United States); Jiang, H.L.; Yang, Z.H. [Basic Department, Jinling Institute of Technology, Nanjing 211169 (China)

    2012-02-15

    We propose a quasi one-dimensional quantum ring-shaped model associated with Rashba spin-orbit (SO) interaction and Aharomov-Bohm flux to study a spin-dependent quantum transport. It is a possible candidate for spintronic current modulators. By tuning SO coupling strength and Fermi energy, we find there is a broad energy range of small vanishing spin transmission in the resonance and antiresonance interferences. More interestingly, the large on/off spin-resolved polarized conductance ratios are robust even in the presence of strong random on-site Anderson-type disorder in devices, which suggests a potential application in the real system.

  9. Utilization of the Suomi National Polar-Orbiting Partnership (NPP Visible Infrared Imaging Radiometer Suite (VIIRS Day/Night Band for Arctic Ship Tracking and Fisheries Management

    Directory of Open Access Journals (Sweden)

    William C. Straka

    2015-01-01

    Full Text Available Maritime ships operating on-board illumination at night appear as point sources of light to highly sensitive low-light imagers on-board environmental satellites. Unlike city lights or lights from offshore gas platforms, whose locations remain stationary from one night to the next, lights from ships typically are ephemeral. Fishing boat lights are most prevalent near coastal cities and along the thermal gradients in the open ocean. Maritime commercial ships also operate lights that can be detected from space. Such observations have been made in a limited way via U.S. Department of Defense satellites since the late 1960s. However, the Suomi National Polar-orbiting Partnership (S-NPP satellite, which carries a new Day/Night Band (DNB radiometer, offers a vastly improved ability for users to observe commercial shipping in remote areas such as the Arctic. Owing to S-NPP’s polar orbit and the DNB’s wide swath (~3040 km, the same location in Polar Regions can be observed for several successive passes via overlapping swaths—offering a limited ability to track ship motion. Here, we demonstrate the DNB’s improved ability to monitor ships from space. Imagery from the DNB is compared with the heritage low-light sensor, the Operational Linescan System (OLS on board the Defense Meteorological Support Program (DMSP satellites, and is evaluated in the context of tracking individual ships in the Polar Regions under both moonlit and moonless conditions. In a statistical sense, we show how DNB observations of ship lights in the East China Sea can be correlated with seasonal fishing activity, while also revealing compelling structures related to regional fishery agreements established between various nations.

  10. Pure spin polarized transport based on Rashba spin—orbit interaction through the Aharonov—Bohm interferometer embodied four-quantum-dot ring

    International Nuclear Information System (INIS)

    rThe spin-polarized linear conductance spectrum and current—voltage characteristics in a four-quantum-dot ring embodied into Aharonov—Bohm (AB) interferometer are investigated theoretically by considering a local Rashba spin—orbit interaction. It shows that the spin-polarized linear conductance and the corresponding spin polarization are each a function of magnetic flux phase at zero bias voltage with a period of 2π, and that Hubbard U cannot influence the electron transport properties in this case. When adjusting appropriately the structural parameter of inter-dot coupling and dot-lead coupling strength, the electronic spin polarization can reach a maximum value. Furthermore, by adjusting the bias voltages applied to the leads, the spin-up and spin-down currents move in opposite directions and pure spin current exists in the configuration space in appropriate situations. Based on the numerical results, such a model can be applied to the design of a spin filter device. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  11. Pure spin polarized transport based on Rashba spin-orbit interaction through the Aharonov-Bohm interferometer embodied four-quantum-dot ring

    Institute of Scientific and Technical Information of China (English)

    Wu Li-Jun; Han Yu

    2013-01-01

    The spin-polarized linear conductance spectrum and current-voltage characteristics in a four-quantum-dot ring embodied into Aharonov-Bohm (AB) interferometer are investigated theoretically by considering a local Rashba spin-orbit interaction.It shows that the spin-polarized linear conductance and the corresponding spin polarization are each a function of magnetic flux phase at zero bias voltage with a period of 2π,and that Hubbard U cannot influence the electron transport properties in this case.When adjusting appropriately the structural parameter of inter-dot coupling and dot-lead coupling strength,the electronic spin polarization can reach a maximum value.Furthermore,by adjusting the bias voltages applied to the leads,the spin-up and spin-down currents move in opposite directions and pure spin current exists in the configuration space in appropriate situations.Based on the numerical results,such a model can be applied to the design of a spin filter device.

  12. The National Polar-orbiting Operational Environmental Satellite System: Capabilities for Atmospheric Remote Sensing for NWP and Climate -- Moving Towards a Global Earth Observation System of Systems

    Science.gov (United States)

    Mango, S. A.; Hinnant, F.; Hoffman, C. W.; Smehil, D. L.; Schneider, S. R.; Simione, S.; Needham, B.; Stockton, D.

    2005-12-01

    Over the last decade, the tri-agency Integrated Program Office (IPO), comprised of the National Oceanic and Atmospheric Administration (NOAA), the Department of Defense (DoD), and the National Aeronautics and Space Administration (NASA), has been managing the development of the National Polar-orbiting Operational Environmental Satellite System (NPOESS). Once operational later this decade, NPOESS will replace NOAA's Polar-orbiting Operational Environmental Satellites (POES) and DoD's Defense Meteorological Satellite Program (DMSP) systems. The IPO, through its Acquisition and Operations contractor, Northrop Grumman, will launch NPOESS spacecraft into three orbital planes to provide a single, national system capable of satisfying both civil and national security requirements for space-based, remotely sensed environmental data. With the development of NPOESS, we are evolving the existing "weather" satellites into integrated environmental observing systems by expanding our capabilities to observe, assess, and predict the total Earth system - ocean, atmosphere, land, and the space environment. The NPOESS will enable more accurate short-term weather forecasts and severe storm warnings and improved monitoring of atmospheric phenomena. NPOESS will also provide continuity of critical data for monitoring, understanding, and predicting climate change and assessing the impacts of climate change on seasonal and longer time scales. For these purposes, the NPOESS Integrated Program Office [IPO] is developing a suite of advanced, atmospheric sounding/probing instruments as a major part of the next generation meteorological, environmental and climate operational satellite system in polar, low earth orbit [LEO]. The IPO is developing the CrIS, Cross-track Infrared Sounder, an Ozone Mapping & Profiler Suite [OMPS]and a Visible and Infrared Imager and Radiometer Suite [VIIRS] and NASA is developing an Advanced Technology Microwave Sounder [ATMS]. These four instruments will be key

  13. Turbulence compensation of an orbital angular momentum and polarization-multiplexed link using a data-carrying beacon on a separate wavelength.

    Science.gov (United States)

    Ren, Yongxiong; Xie, Guodong; Huang, Hao; Li, Long; Ahmed, Nisar; Yan, Yan; Lavery, Martin P J; Bock, Robert; Tur, Moshe; Neifeld, Mark A; Boyd, Robert W; Shapiro, Jeffrey H; Willner, Alan E

    2015-05-15

    We investigate the sensing of a data-carrying Gaussian beacon on a separate wavelength as a means to provide the information necessary to compensate for the effects of atmospheric turbulence on orbital angular momentum (OAM) and polarization-multiplexed beams in a free-space optical link. The influence of the Gaussian beacon's wavelength on the compensation of the OAM beams at 1560 nm is experimentally studied. It is found that the compensation performance degrades slowly with the increase in the beacon's wavelength offset, in the 1520-1590 nm band, from the OAM beams. Using this scheme, we experimentally demonstrate a 1 Tbit/s OAM and polarization-multiplexed link through emulated dynamic turbulence with a data-carrying beacon at 1550 nm. The experimental results show that the turbulence effects on all 10 data channels, each carrying a 100 Gbit/s signal, are mitigated efficiently, and the power penalties after compensation are below 5.9 dB for all channels. The results of our work might be helpful for the future implementation of a high-capacity OAM, polarization and wavelength-multiplexed free-space optical link that is affected by atmospheric turbulence. PMID:26393711

  14. The science case for a modern, multi-wavelength, polarization-sensitive LIDAR in orbit around Mars

    CERN Document Server

    Brown, Adrian J; Byrne, Shane; Sun, Wenbo; Titus, Timothy N; Colaprete, Anthony; Wolff, Michael J; Videen, Gorden

    2014-01-01

    We present the scientific case to build a multiple-wavelength, active, near-infrared (NIR) instrument to measure the reflected intensity and polarization characteristics of backscattered radiation from planetary surfaces and atmospheres. We focus on the ability of such an instrument to enhance, perhaps revolutionize, our understanding of climate, volatiles and astrobiological potential of modern-day Mars.

  15. High altitude subhyaloid hemorrhage

    OpenAIRE

    Abdul Hanifudin; Lik Thai Lim; Elliott Yann Ah-Kee; Tarek El-Khashab

    2015-01-01

    Subhyaloid hemorrhages can occur as a result of exposure to high altitude. We hereby report a clinical picture of subhyaloid hemorrhage associated with high altitude. The case demonstrates optical coherence tomography findings that aid diagnosis of subhyaloid hemorrhage.

  16. Fulminant high altitude blindness.

    Science.gov (United States)

    Mashkovskiy, Evgeny; Szawarski, Piotr; Ryzhkov, Pavel; Goslar, Tomaz; Mrak, Irena

    2016-06-01

    Prolonged altitude exposure even with acclimatization continues to present a physiological challenge to all organ systems including the central nervous system. We describe a case of a 41-year-old Caucasian female climber who suffered severe visual loss that was due to possible optic nerve pathology occurring during a high altitude expedition in the Himalayas. This case is atypical of classic high altitude cerebral oedema and highlights yet another danger of prolonged sojourn at extreme altitudes. PMID:27601532

  17. Dynamics of the ring current and ion fluxes at low altitudes during the February 27-28, 2014 magnetic storm

    Science.gov (United States)

    Kalegaev, V. V.; Vlasova, N. A.; Nazarkov, I. S.

    2015-11-01

    A comparative analysis has been performed for the dynamics of the ring current and ion fluxes at low altitudes during the February 27, 2014 geomagnetic storm. We use concurrent experimental data on ion fluxes with an energy of ~30 to 250 keV in the near-equatorial magnetospheric region at altitudes up to 30000 km from the Van Allen Probes satellite and at a polar orbit up to 1000 km from the Polar Orbiting Environmental Satellite (POES). The main phase of the storm was characterized by increased ion fluxes with E 100 keV, both near the ring current and in the low-orbit equatorial region, reflecting the fact that the particle spectrum of the ring current in the main phase of the storm becomes softed. The observed phenomenon may originate from the precipitation of ring-current particles registered by POES below the isotropization boundary. It was shown that the variations in ion fluxes at low orbit during the geomagnetic storm generally reflect the ring current dynamics, although each region under consideration has its own specific features complementing the general pattern of the Earth's magnetosphere dynamics.

  18. Theoretical description of atomic photoionization by an attosecond XUV pulse in a strong laser field: effects of rescattering and orbital polarization

    International Nuclear Information System (INIS)

    A theoretical description of atomic photoionization by attosecond pulses in the presence of an intense laser pulse is presented. It is based on the numerical solving of the non-stationary Schroedinger equation which includes on an equal footing the realistic atomic potential and the electric fields of both pulses. The calculated energy spectra and angular distributions of photoelectrons are compared with those obtained using a simple approximate model based on the strong-field approximation. The agreement is excellent for large energy of photoelectrons. When the energy is small, the rescattering of electrons by the ionic core affects the cross section considerably making the strong-field approximation inadequate. Influence of the electron orbital polarization on the ionization cross section is investigated

  19. KEPLER-63b: A GIANT PLANET IN A POLAR ORBIT AROUND A YOUNG SUN-LIKE STAR

    OpenAIRE

    Sanchis-Ojeda, Roberto; Winn, Joshua N.; Marcy, Geoffrey W.; Howard, Andrew W.; Isaacson, Howard; Johnson, John Asher; Torres, Guillermo; Albrecht, Simon; Campante, Tiago L.; Chaplin, William J.; Davies, Guy R.; Lund, Mikkel L.; Carter, Joshua A.; Dawson, Rebekah I.; Buchhave, Lars A.

    2013-01-01

    We present the discovery and characterization of a giant planet orbiting the young Sun-like star Kepler-63 (KOI-63, m [subscript Kp] = 11.6, T [subscript eff] = 5576 K, M [star] = 0.98 M [subscript ☉]). The planet transits every 9.43 days, with apparent depth variations and brightening anomalies caused by large starspots. The planet's radius is 6.1 ± 0.2 R [subscript ⊕], based on the transit light curve and the estimated stellar parameters. The planet's mass could not be measured with the exi...

  20. Sextant measures spacecraft altitude without gravitational reference

    Science.gov (United States)

    1966-01-01

    Horizon-sensing sextant measures the altitude of an orbiting spacecraft without gravitational reference by optically measuring the dip angle to the horizon along a line of sight in each of two planes. The sextant scans over a relatively limited field of view.

  1. Data catalog series for space science and applications flight missions. Volume 2A: Descriptions of geostationary and high-altitude scientific spacecraft and investigations

    Science.gov (United States)

    Hills, H. K. (Editor); Littlefield, R. G. (Editor); Schofield, N. J. (Editor); Vetts, J. I. (Editor)

    1982-01-01

    Data from Earth-orbiting spacecraft at geostationary and higher altitudes was cataloged. Three lunar-orbiting spacecraft and some others whose apogees did not attain the geostationary altitude are included.

  2. Adaptation to High Altitude

    Directory of Open Access Journals (Sweden)

    H. S. Nayar

    1984-10-01

    Full Text Available Hypoxia is inconsequential for physiologically fit persons below an effective altitude of 2640 metres. At higher altitudes, the adaptation is brought about by four main factors, viz., hyperventilation, increased diffusion of oxygen across alveolar membrane, erythrocythemia and maintenance of body hydration. Carbon dioxide sensitivity is markedly elevated at high altitude, both in sojourners and acclimatized low-landers. The greater pulmonary diffusing capacity observed in high altitude natives is well documented. RBC count, haemoglobin and haematocrit increase whereas arterial oxyhaemoglobin saturation percentage decreases at high altitude. Diuretics (Furosemide have no role in adaptation to high altitude and adequate body hydration must be maintained.The ultimate adaptive mechanisms occur at tissue level which facilitate the diffusion of oxygen from blood to tissue and its utilization. The work capacity decreases at high altitude and a relationship between load carried and speed of marching has been determined at various altitudes. Although altitude has an adverse effect on process of cold acclimatization, yet it is possible to induce cold acclimatization by exposing subjects to a temperature of 0° to -5°C for a period of three hours daily for three weeks. The caloric requirements increase at high altitudes and are 4,286 K Cal and 4,380 K Cal at 13000 feet (3950 m and 17000 feet (5170 m, respectively.

  3. Lunar Reconnaissance Orbiter (LRO) Observations with the Lunar Exploration Neutron Detector (LEND): Neutron Suppression Regions (NSR) and Polar Hydrogen

    Science.gov (United States)

    Chin, G.; Mitrofanov, I. G.; Boynton, W. V.; Golovin, D. V.; Evans, L. G.; Harshman, K.; Kozyrev, A. S.; Litvak, M. L.; McClanahan, T.; Milikh, G. M.; Sagdeev, R.; Sanin, A. B.; Shevchenko, V.; Shvetsov, V.; Smith, D.; Starr, R.; Trombka, J.; Zuber, M.

    2011-01-01

    Orbital detection of neutrons has become the dominant remote sensing technique for detecting and inferring H concentrations and its spatial distribution beneath planetary surfaces [Lawrence et al, (2010) Icarus, 205, pp. 195-209, Mitrofanov et al (2007) Science 297(5578), 78-81]. Indications for the presence of localized and relatively high water content was provided by LRO and LCROSS. LEND identified Cabeus, as the most promising LCROSS impact site [Mitrofanov I. et al. (2010) Science, 330, 483], and instruments onboard LRO and LCROSS have measured signatures of water, H2 and other volatiles in the impact plume [Colaprete A. et al. (2010) Science, 339,463, Gladstone R. et al. (2010) Science, 330, 472].

  4. Spontaneous emergence of non-planar electron orbits during direct laser acceleration by a linearly polarized laser pulse

    Science.gov (United States)

    Arefiev, A. V.; Khudik, V. N.; Robinson, A. P. L.; Shvets, G.; Willingale, L.

    2016-02-01

    An electron irradiated by a linearly polarized relativistic intensity laser pulse in a cylindrical plasma channel can gain significant energy from the pulse. The laser electric and magnetic fields drive electron oscillations in a plane making it natural to expect the electron trajectory to be flat. We show that strong modulations of the relativistic γ-factor associated with the energy enhancement cause the free oscillations perpendicular to the plane of the driven motion to become unstable. As a consequence, out of plane displacements grow to become comparable to the amplitude of the driven oscillations and the electron trajectory becomes essentially three-dimensional, even if at an early stage of the acceleration it was flat. The development of the instability profoundly affects the x-ray emission, causing considerable divergence of the radiation perpendicular to the plane of the driven oscillations, while also reducing the overall emitted energy.

  5. Spontaneous emergence of non-planar electron orbits during direct laser acceleration by a linearly polarized laser pulse

    CERN Document Server

    Arefiev, A V; Robinson, A P L; Shvets, G; Willingale, L

    2015-01-01

    An electron irradiated by a linearly polarized relativistic intensity laser pulse in a cylindrical plasma channel can gain significant energy from the pulse. The laser electric and magnetic fields drive electron oscillations in a plane making it natural to expect the electron trajectory to be flat. We show that strong modulations of the relativistic $\\gamma$-factor associated with the energy enhancement cause the free oscillations perpendicular to the plane of the driven motion to become unstable. As a consequence, out of plane displacements grow to become comparable to the amplitude of the driven oscillations and the electron trajectory becomes essentially three-dimensional, even if at an early stage of the acceleration it was flat. The development of the instability profoundly affects the x-ray emission, causing considerable divergence of the radiation perpendicular to the plane of the driven oscillations, while also reducing the overall emitted energy.

  6. HIGH-ALTITUDE ILLNESS

    Directory of Open Access Journals (Sweden)

    Dwitya Elvira

    2015-05-01

    Full Text Available AbstrakHigh-altitude illness (HAI merupakan sekumpulan gejala paru dan otak yang terjadi pada orang yang baru pertama kali mendaki ke ketinggian. HAI terdiri dari acute mountain sickness (AMS, high-altitude cerebral edema (HACE dan high-altitude pulmonary edema (HAPE. Tujuan tinjauan pustaka ini adalah agar dokter dan wisatawan memahami risiko, tanda, gejala, dan pengobatan high-altitude illness. Perhatian banyak diberikan terhadap penyakit ini seiring dengan meningkatnya popularitas olahraga ekstrim (mendaki gunung tinggi, ski dan snowboarding dan adanya kemudahan serta ketersediaan perjalanan sehingga jutaan orang dapat terpapar bahaya HAI. Di Pherice, Nepal (ketinggian 4343 m, 43% pendaki mengalami gejala AMS. Pada studi yang dilakukan pada tempat wisata di resort ski Colorado, Honigman menggambarkan kejadian AMS 22% pada ketinggian 1850 m sampai 2750 m, sementara Dean menunjukkan 42% memiliki gejala pada ketinggian 3000 m. Aklimatisasi merupakan salah satu tindakan pencegahan yang dapat dilakukan sebelum pendakian, selain beberapa pengobatan seperti asetazolamid, dexamethasone, phosopodiestrase inhibitor, dan ginko biloba.Kata kunci: high-altitude illness, acute mountain sickness, edema cerebral, pulmonary edema AbstractHigh-altitude illness (HAI is symptoms of lung and brain that occurs in people who first climb to altitude. HAI includes acute mountain sickness (AMS, high-altitude cerebral edema (HACE and high altitude pulmonary edema (HAPE. The objective of this review was to understand the risks, signs, symptoms, and treatment of high-altitude illness. The attention was given to this disease due to the rising popularity of extreme sports (high mountain climbing, skiing and snowboarding and the ease and availability of the current travelling, almost each year, millions of people could be exposed to the danger of HAI. In Pherice, Nepal (altitude 4343 m, 43% of climbers have symptoms of AMS. Furthermore, in a study conducted at sites in

  7. Analysis of fine ELF wave structures observed poleward from the ionospheric trough by the low-altitude satellite DEMETER

    OpenAIRE

    Parrot, Michel; Nĕmec, František; Santolík, Ondřej

    2014-01-01

    International audience DEMETER was a three-axis stabilized Earth-pointing spacecraft launched on 29 June 2004 into a low-altitude (710 km) polar and circular orbit that was subsequently lowered to 650 km until the end of the mission in December 2010. DEMETER measured electromagnetic waves all around the Earth except at magnetic invariant latitudes >65°. The frequency range for the electric field was from DC up to 3.5 MHz and for the magnetic field from a few hertz up to 20 kHz. Electromagn...

  8. [Mountaineering and altitude sickness].

    Science.gov (United States)

    Maggiorini, M

    2001-06-01

    Almost every second trekker or climber develops two to three symptoms of the high altitude illness after a rapid ascent (> 300 m/day) to an altitude above 4000 m. We distinguish two forms of high altitude illness, a cerebral form called acute mountain sickness and a pulmonary form called high altitude pulmonary edema. Essentially, acute mountain sickness is self-limiting and benign. Its symptoms are mild to moderate headache, loss of appetite, nausea, dizziness and insomnia. Nausea rarely progresses to vomiting, but if it does, this may anticipate a progression of the disease into the severe form of acute mountain sickness, called high altitude cerebral edema. Symptoms and signs of high altitude cerebral edema are severe headache, which is not relieved by acetaminophen, loss of movement coordination, ataxia and mental deterioration ending in coma. The mechanisms leading to acute mountain sickness are not very well understood; the loss of cerebral autoregulation and a vasogenic type of cerebral edema are being discussed. High altitude pulmonary edema presents in roughly twenty percent of the cases with mild symptoms of acute mountain sickness or even without any symptoms at all. Symptoms associated with high altitude pulmonary edema are incapacitating fatigue, chest tightness, dyspnoe at the minimal effort that advances to dyspnoe at rest and orthopnoe, and a dry non-productive cough that progresses to cough with pink frothy sputum due to hemoptysis. The hallmark of high altitude pulmonary edema is an exaggerated hypoxic pulmonary vasoconstriction. Successful prophylaxis and treatment of high altitude pulmonary edema using nifedipine, a pulmonary vasodilator, indicates that pulmonary hypertension is crucial for the development of high altitude pulmonary edema. The primary treatment of high altitude illness consists in improving hypoxemia and acclimatization. For prophylaxis a slow ascent at a rate of 300 m/day is recommended, if symptoms persist, acetazolamide at a

  9. High altitude aircraft flight tests

    Science.gov (United States)

    Helmken, Henry; Emmons, Peter; Homeyer, David

    1996-03-01

    In order to make low earth orbit L-band propagation measurements and test new voice communication concepts, a payload was proposed and accepted for flight aboard the COMET (now METEOR) spacecraft. This Low Earth Orbiting EXperiment payload (LEOEX) was designed and developed by Motorola Inc. and sponsored by the Space Communications Technology Center (SCTC), a NASA Center for the Commercial Development of Space (CCDS) located at Florida Atlantic University. In order to verify the LEOEX payload for satellite operation and obtain some preliminary propagation data, a series of 9 high altitude aircraft (SR-71 and ER-2) flight tests were conducted. These flights took place during a period of 7 months, from October 1993 to April 1994. This paper will summarize the operation of the LEOEX payload and the particular configuration used for these flights. The series of flyby tests were very successful and demonstrated how bi-directional, Time Division Multiple Access (TDMA) voice communication will work in space-to-ground L-band channels. The flight tests also acquired propagation data which will be representative of L-band Low Earth Orbiting (LEO) communication systems. In addition to verifying the LEOEX system operation, it also uncovered and ultimately aided the resolution of several key technical issues associated with the payload.

  10. Illuminating the Capabilities of the Suomi National Polar-Orbiting Partnership (NPP Visible Infrared Imaging Radiometer Suite (VIIRS Day/Night Band

    Directory of Open Access Journals (Sweden)

    Steven D. Miller

    2013-12-01

    Full Text Available Daytime measurements of reflected sunlight in the visible spectrum have been a staple of Earth-viewing radiometers since the advent of the environmental satellite platform. At night, these same optical-spectrum sensors have traditionally been limited to thermal infrared emission, which contains relatively poor information content for many important weather and climate parameters. These deficiencies have limited our ability to characterize the full diurnal behavior and processes of parameters relevant to improved monitoring, understanding and modeling of weather and climate processes. Visible-spectrum light information does exist during the nighttime hours, originating from a wide variety of sources, but its detection requires specialized technology. Such measurements have existed, in a limited way, on USA Department of Defense satellites, but the Suomi National Polar-orbiting Partnership (NPP satellite, which carries a new Day/Night Band (DNB radiometer, offers the first quantitative measurements of nocturnal visible and near-infrared light. Here, we demonstrate the expanded potential for nocturnal low-light visible applications enabled by the DNB. Via a combination of terrestrial and extraterrestrial light sources, such observations are always available—expanding many current existing applications while enabling entirely new capabilities. These novel low-light measurements open doors to a wealth of new interdisciplinary research topics while lighting a pathway toward the optimized design of follow-on satellite based low light visible sensors.

  11. Ear - blocked at high altitudes

    Science.gov (United States)

    High altitudes and blocked ears; Flying and blocked ears; Eustachian tube dysfunction - high altitude ... you are going up or coming down from high altitudes. Chewing gum the entire time you are changing ...

  12. Estimation of high altitude Martian dust parameters

    Science.gov (United States)

    Pabari, Jayesh; Bhalodi, Pinali

    2016-07-01

    Dust devils are known to occur near the Martian surface mostly during the mid of Southern hemisphere summer and they play vital role in deciding background dust opacity in the atmosphere. The second source of high altitude Martian dust could be due to the secondary ejecta caused by impacts on Martian Moons, Phobos and Deimos. Also, the surfaces of the Moons are charged positively due to ultraviolet rays from the Sun and negatively due to space plasma currents. Such surface charging may cause fine grains to be levitated, which can easily escape the Moons. It is expected that the escaping dust form dust rings within the orbits of the Moons and therefore also around the Mars. One more possible source of high altitude Martian dust is interplanetary in nature. Due to continuous supply of the dust from various sources and also due to a kind of feedback mechanism existing between the ring or tori and the sources, the dust rings or tori can sustain over a period of time. Recently, very high altitude dust at about 1000 km has been found by MAVEN mission and it is expected that the dust may be concentrated at about 150 to 500 km. However, it is mystery how dust has reached to such high altitudes. Estimation of dust parameters before-hand is necessary to design an instrument for the detection of high altitude Martian dust from a future orbiter. In this work, we have studied the dust supply rate responsible primarily for the formation of dust ring or tori, the life time of dust particles around the Mars, the dust number density as well as the effect of solar radiation pressure and Martian oblateness on dust dynamics. The results presented in this paper may be useful to space scientists for understanding the scenario and designing an orbiter based instrument to measure the dust surrounding the Mars for solving the mystery. The further work is underway.

  13. High Altitude and Heart

    OpenAIRE

    Murat Yalcin; Ejder Kardesoglu; Zafer Isilak

    2011-01-01

    Nowadays, situations associated with high altitude such as mountaineering, aviation increasingly draw the attention of people. Gas pressure decreases and hypoxia is encountered when climbing higher. Physiological and pathological responses of human body to different heights are different. Therefore, physiological and pathological changes that may occur together with height and to know the clinical outcomes of these are important . Acute mountain sickness caused by high altitude and high altit...

  14. Endurance training at altitude.

    Science.gov (United States)

    Saunders, Philo U; Pyne, David B; Gore, Christopher J

    2009-01-01

    Since the 1968 Olympic Games when the effects of altitude on endurance performance became evident, moderate altitude training ( approximately 2000 to 3000 m) has become popular to improve competition performance both at altitude and sea level. When endurance athletes are exposed acutely to moderate altitude, a number of physiological responses occur that can comprise performance at altitude; these include increased ventilation, increased heart rate, decreased stroke volume, reduced plasma volume, and lower maximal aerobic power ((.)Vo(2max)) by approximately 15% to 20%. Over a period of several weeks, one primary acclimatization response is an increase in the volume of red blood cells and consequently of (.)Vo(2max). Altitudes > approximately 2000 m for >3 weeks and adequate iron stores are required to elicit these responses. However, the primacy of more red blood cells for superior sea-level performance is not clear-cut since the best endurance athletes in the world, from Ethiopia (approximately 2000 to 3000 m), have only marginally elevated hemoglobin concentrations. The substantial reduction in (.)Vo(2max) of athletes at moderate altitude implies that their training should include adequate short-duration (approximately 1 to 2 min), high-intensity efforts with long recoveries to avoid a reduction in race-specific fitness. At the elite level, athlete performance is not dependent solely on (.)Vo(2max), and the "smallest worthwhile change" in performance for improving race results is as little as 0.5%. Consequently, contemporary statistical approaches that utilize the concept of the smallest worthwhile change are likely to be more appropriate than conventional statistical methods when attempting to understand the potential benefits and mechanisms of altitude training. PMID:19519223

  15. Altitude Modulates Concussion Incidence

    OpenAIRE

    Smith, David W.; Myer, Gregory D; Currie, Dustin W.; Comstock, R Dawn; Clark, Joseph F.; Bailes, Julian E.

    2013-01-01

    Background: Recent research indicates that the volume and/or pressure of intracranial fluid, a physiology affected by one’s altitude (ie, elevation above sea level), may be associated with the likelihood and/or severity of a concussion. The objective was to employ an epidemiological field investigation to evaluate the relationship between altitude and concussion rate in high school sports. Hypothesis: Because of the physiologies that occur during acclimatization, including a decline in intrac...

  16. Polar Stratigraphy

    Science.gov (United States)

    1999-01-01

    These three images were taken on three different orbits over the north polar cap in April 1999. Each shows a different part of the same ice-free trough. The left and right images are separated by a distance of more than 100 kilometers (62 miles). Note the similar layers in each image.

  17. Towards high temporal and moderate spatial resolutions in the remote sensing retrieval of evapotranspiration by combining geostationary and polar orbit satellite data

    Science.gov (United States)

    Barrios, José Miguel; Ghilain, Nicolas; Arboleda, Alirio; Gellens-Meulenberghs, Françoise

    2014-05-01

    Evapotranspiration (ET) is the water flux going from the surface into the atmosphere as result of soil and surface water evaporation and plant transpiration. It constitutes a key component of the water cycle and its quantification is of crucial importance for a number of applications like water management, climatic modelling, agriculture monitoring and planning, etc. Estimating ET is not an easy task; specially if large areas are envisaged and various spatio-temporal patterns of ET are present as result of heterogeneity in land cover, land use and climatic conditions. In this respect, spaceborne remote sensing (RS) provides the only alternative to continuously measure surface parameters related to ET over large areas. The Royal Meteorological Institute (RMI) of Belgium, in the framework of EUMETSAT's "Land Surface Analysis-Satellite Application Facility" (LSA-SAF), has developed a model for the estimation of ET. The model is forced by RS data, numerical weather predictions and land cover information. The RS forcing is derived from measurements by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard the Meteosat Second Generation (MSG) satellite. This ET model is operational and delivers ET estimations over the whole field of view of the MSG satellite (Europe, Africa and Eastern South America) (http://landsaf.meteo.pt) every 30 minutes. The spatial resolution of MSG is 3 x 3 km at subsatellite point and about 4 x 5 km in continental Europe. The spatial resolution of this product may constrain its full exploitation as the interest of potential users (farmers and natural resources scientists) may lie on smaller spatial units. This study aimed at testing methodological alternatives to combine RS imagery (geostationary and polar orbit satellites) for the estimation of ET such that the spatial resolution of the final product is improved. In particular, the study consisted in the implementation of two approaches for combining the current ET estimations with

  18. Coupling between the charge carriers and lattice distortions via modulation of the orbital angular momentum m sub l =0 of the 3d holes by polarized XAS spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pompa, M.; Turtu, S.; Campanella, F.; Pettiti, I.; Udron, D. (INFM, Dipt. di Fisica, Rome-1 Univ. (Italy)); Bianconi, A. (INFM, Dipt. di Fisica, Rome-1 Univ. (Italy) Univ. of L' Aquila (Italy)); Flank, A.M.; Lagarde, P. (LURE, 91 - Orsay (France)); Li, C. (Inst. of Physics, Academia Sinica, Beijing (China))

    1991-12-01

    The change of the orbital angular momentum m{sub l} of the Cu 3d holes going from the insulating to the metallic phase has been studied in several families of high Tc superconductors. The symmetry of the 3d{sup 9}L states in the metallic phase has been studied by quantitative analysis of the variation of polarized Cu L{sub 3} X-ray absorption spectra. At a doping level n{sub h} {approx equal} 15% we have found 10% of Zhang-Rice singlets 3d{sub x}2{sub -y}2 L(b{sub 1}) and 5% of 3d{sub 3z}2{sub -r}2L(a{sub 1}) states. Therefore the percentage of the 3d{sub 3z}2{sub -r}2L states on the total number of the 3d{sup 9}L states is about 30% i.e. much larger than the probability of single hole states 3d{sub 3z}2{sub -r}2 in the insulating phase. The EXAFS and XANES studies of the Cu site structure and dynamics in Bi{sub 2}Sr{sub 2}Ca{sub 1-x}Y{sub x}Cu{sub 2}O{sub {proportional to}} {sub 8} system point toward the coupling of the charge carriers with distortions of the Cu sites driven by the m{sub l}=0 character of the Cu 3d holes that can be called a 3d{sub z}2{sub -r}2 polaron. (orig.).

  19. Feasibility demonstration for calibrating Suomi-National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite day/night band using Dome C and Greenland under moon light

    Science.gov (United States)

    Qiu, Shi; Shao, Xi; Cao, Changyong; Uprety, Sirish

    2016-01-01

    The day/night band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi National Polar-orbiting Partnership (Suomi-NPP) represents a major advancement in night time imaging capabilities. DNB covers almost seven orders of magnitude in its dynamic range from full sunlight to half-moon. To achieve this large dynamic range, it uses four charge-coupled device arrays in three gain stages. The low gain stage (LGS) gain is calibrated using the solar diffuser. In operations, the medium and high gain stage values are determined by multiplying the gain ratios between the medium gain stage, and LGS, and high gain stage (HGS) and LGS, respectively. This paper focuses on independently verifying the radiometric accuracy and stability of DNB HGS using DNB observations of ground vicarious calibration sites under lunar illumination at night. Dome C in Antarctica in the southern hemisphere and Greenland in the northern hemisphere are chosen as the vicarious calibration sites. Nadir observations of these high latitude regions by VIIRS are selected during perpetual night season, i.e., from April to August for Dome C and from November to January for Greenland over the years 2012 to 2013. Additional selection criteria, such as lunar phase being more than half-moon and no influence of straylight effects, are also applied in data selection. The lunar spectral irradiance model, as a function of Sun-Earth-Moon distances and lunar phase, is used to determine the top-of-atmosphere reflectance at the vicarious site. The vicariously derived long-term reflectance from DNB observations agrees with the reflectance derived from Hyperion observations. The vicarious trending of DNB radiometric performance using DOME-C and Greenland under moon light shows that the DNB HGS radiometric variability (relative accuracy to lunar irradiance model and Hyperion observation) is within 8%. Residual variability is also discussed.

  20. Characteristics of anomalous Hall effect in spin-polarized two-dimensional electron gases in the presence of both intrinsic, extrinsic, and external electric-field induced spin-orbit couplings

    Institute of Scientific and Technical Information of China (English)

    Liu Song; Yan Yu-Zhen; Hu Liang-Bin

    2012-01-01

    The various competing contributions to the anomalous Hall effect in spin-polarized two-dimensional electron gases in the presence of both intrinsic,extrinsic and external electric-field induced spin-orbit coupling were investigated theoretically.Based on a unified semiclassical theoretical approach,it is shown that the total anomalous Hall conductivity can be expressed as the sum of three distinct contributions in the presence of these competing spin-orbit interactions,namely an intrinsic contribution determined by the Berry curvature in the momentum space,an extrinsic contribution determined by the modified Bloch band group velocity and an extrinsic contribution determined by spin-orbit-dependent impurity scattering.The characteristics of these competing contributions are discussed in detail in the paper.

  1. A statistical study of the low-altitude ionospheric magnetic fields over the north pole of Venus

    Science.gov (United States)

    Zhang, T. L.; Baumjohann, W.; Russell, C. T.; Villarreal, M. N.; Luhmann, J. G.; Teh, W. L.

    2015-08-01

    Examination of Venus Express (VEX) low-altitude ionospheric magnetic field measurements during solar minimum has revealed the presence of strong magnetic fields at low altitudes over the north pole of Venus. A total of 77 events with strong magnetic fields as VEX crossed the northern polar region were identified between July 2008 and October 2009. These events all have strong horizontal fields, slowly varying with position. Using the superposed epoch method, we find that the averaged peak field is about 45 nT, which is well above the average ambient ionospheric field of 20 nT, with a full width at half maximum duration of 32 s, equivalent to a width of about 300 km. Considering the field orientation preference and spacecraft trajectory geometry, we conclude that these strong fields are found over the northern hemisphere with an occurrence frequency of more than 33% during solar minimum. They do not show a preference for any particular interplanetary magnetic field (IMF) orientation. However, they are found over the geographic pole more often when the interplanetary field is in the Venus orbital plane than when it is perpendicular to the orbital plane of Venus. The structures were found most frequently in the -E hemisphere, determined from the IMF orientation. The enhanced magnetic field is mainly quasi perpendicular to solar wind flow direction, and it is suggested that these structures form in the low-altitude collisional ionosphere where the diffusion and convection times are long.

  2. High Altitude and Heart

    Directory of Open Access Journals (Sweden)

    Murat Yalcin

    2011-04-01

    Full Text Available Nowadays, situations associated with high altitude such as mountaineering, aviation increasingly draw the attention of people. Gas pressure decreases and hypoxia is encountered when climbing higher. Physiological and pathological responses of human body to different heights are different. Therefore, physiological and pathological changes that may occur together with height and to know the clinical outcomes of these are important . Acute mountain sickness caused by high altitude and high altitude cerebral edema are preventable diseases with appropriate precautions. Atmospheric oxygen decreasing with height, initiates many adaptive mechanisms. These adaptation mechanisms and acclimatization vary widely among individuals because of reasons such as environmental factors, exercise and cold. High altitude causes different changes in the cardiovascular system with various mechanisms. Although normal individuals easily adapt to these changes, this situation can lead to undesirable results in people with heart disease. For this reason, it should be known the effective evaluation of the people with known heart disease before traveling to high altitude and the complications due to the changes with height and the recommendations can be made to these patients. [TAF Prev Med Bull 2011; 10(2.000: 211-222

  3. High-altitude medicine

    Directory of Open Access Journals (Sweden)

    Paralikar Swapnil

    2010-01-01

    Full Text Available Sojourns to high altitude have become common for recreation and adventure purposes. In most individuals, gradual ascent to a high altitude leads to a series of adaptive changes in the body, termed as acclimatization. These include changes in the respiratory, cardiovascular, hematologic systems and cellular adaptations that enhance oxygen delivery to the tissues and augment oxygen uptake. Thus there is an increase in pulmonary ventilation, increase in diffusing capacity in the lung, an increase in the cardiac output and increase in the red blood cell count due to an increase in erythropoietin secretion by the kidney, all of which enhance oxygen delivery to the cells. Cellular changes like increase in the number of mitochondria and augmentation of cytochrome oxidase systems take months or years to develop. Too rapid an ascent or inability to acclimatize leads to high-altitude illnesses. These include acute mountain sickness (AMS, high-altitude cerebral edema (HACE and high-altitude pulmonary edema (HAPE. Acute mountain sickness is self limiting if recognized early. Both HACE and HAPE are life threatening and need to be treated aggressively. The key to treatment of these illnesses is early recognition; administration of supplemental oxygen; and descent if required. Drugs like acetazolamide, dexamethasone, nifedipine may be administered as recommended.

  4. Fourier Series Approximations to J2-Bounded Equatorial Orbits

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2014-01-01

    Full Text Available The current paper offers a comprehensive dynamical analysis and Fourier series approximations of J2-bounded equatorial orbits. The initial conditions of heterogeneous families of J2-perturbed equatorial orbits are determined first. Then the characteristics of two types of J2-bounded orbits, namely, pseudo-elliptic orbit and critical circular orbit, are studied. Due to the ambiguity of the closed-form solutions which comprise the elliptic integrals and Jacobian elliptic functions, showing little physical insight into the problem, a new scheme, termed Fourier series expansion, is adopted for approximation herein. Based on least-squares fitting to the coefficients, the solutions are expressed with arbitrary high-order Fourier series, since the radius and the flight time vary periodically as a function of the polar angle. As a consequence, the solutions can be written in terms of elementary functions such as cosines, rather than complex mathematical functions. Simulations enhance the proposed approximation method, showing bounded and negligible deviations. The approximation results show a promising prospect in preliminary orbits design, determination, and transfers for low-altitude spacecrafts.

  5. The CAMEO barium release - E/parallel/ fields over the polar cap

    Science.gov (United States)

    Heppner, J. P.; Miller, M. L.; Pongratz, M. B.; Smith, G. M.; Smith, L. L.; Mende, S. B.; Nath, N. R.

    1981-01-01

    Four successive thermite barium releases at an altitude of 965 km over polar cap invariant latitudes 84 to 76 deg near magnetic midnight were conducted from the orbiting second stage of the vehicle that launched Nimbus 7; the releases were made as part of the CAMEO (Chemically Active Material Ejected in Orbit) program. This was the first opportunity to observe the behavior of conventional barium release when conducted at orbital velocity in the near-earth magnetic field. The principal unexpected characteristic in the release dynamics was the high, 1.4 to 2.6 km/s, initial Ba(+) expansion velocity relative to an expected velocity of 0.9 km/s. Attention is also given to neutral cloud expansion, initial ion cloud expansion, convective motion, and the characteristics of field-aligned motion. The possibility of measuring parallel electric fields over the polar cap by observing perturbations in the motion of the visible ions is assessed.

  6. Orbit determination and gravity field recovery from tracking data to the Lunar Reconnaissance Orbiter

    Science.gov (United States)

    Maier, Andrea; Baur, Oliver

    2015-04-01

    The Lunar Reconnaissance Orbiter (LRO), launched in 2009, is well suited for the estimation of the long wavelengths of the lunar gravity field due to its low altitude of 50 km. Further, the orbit of LRO was polar for two years providing global coverage. The satellite has been primarily tracked via S-band (mainly two-way Doppler range-rates and two-way radiometric ranges) from the dedicated station in White Sands and from the Universal Space Network (USN). Due to the onboard altimeter the orbital precision requirement in the radial direction was rigorously defined as 1m. Because simulation studies before LRO's launch showed that this precision could not be reached with S-band observations alone, it was decided to additionally track LRO via optical laser ranges. It is worthwhile to point out that LRO is the first spacecraft in interplanetary space routinely tracked with optical one-way laser ranges. Gravity field recovery from orbit perturbations is intrinsically related to precise orbit determination. This is why considerable effort was made to find the optimum settings for orbit modeling. For a time span of three months we conducted a series of orbit overlapping tests based on Doppler observations to find the optimum arc length and the optimum set of empirical parameters. The analysis of observation residuals and orbit overlap differences showed that the estimated orbits are most precise when subdividing the time span into 2.5 days and estimating one constant empirical acceleration in along track direction. These settings were then used to analyze 13 months of Doppler data to LRO. The processing of the optical one-way laser was difficult due to the involvement of two non-synchronous clocks in one measurement (one clock at the ground station and one clock onboard LRO). The NASA software GEODYN, which was used for orbit determination and parameter estimation, models the LRO clock using a drift rate (first-order term) and an aging rate (second-order term). It seems

  7. Jupiter's High-Altitude Clouds

    Science.gov (United States)

    2007-01-01

    The New Horizons Multispectral Visible Imaging Camera (MVIC) snapped this incredibly detailed picture of Jupiter's high-altitude clouds starting at 06:00 Universal Time on February 28, 2007, when the spacecraft was only 2.3 million kilometers (1.4 million miles) from the solar system's largest planet. Features as small as 50 kilometers (30 miles) are visible. The image was taken through a narrow filter centered on a methane absorption band near 890 nanometers, a considerably redder wavelength than what the eye can see. Images taken through this filter preferentially pick out clouds that are relatively high in the sky of this gas giant planet because sunlight at the wavelengths transmitted by the filter is completely absorbed by the methane gas that permeates Jupiter's atmosphere before it can reach the lower clouds. The image reveals a range of diverse features. The south pole is capped with a haze of small particles probably created by the precipitation of charged particles into the polar regions during auroral activity. Just north of the cap is a well-formed anticyclonic vortex with rising white thunderheads at its core. Slightly north of the vortex are the tendrils of some rather disorganized storms and more pinpoint-like thunderheads. The dark 'measles' that appear a bit farther north are actually cloud-free regions where light is completely absorbed by the methane gas and essentially disappears from view. The wind action considerably picks up in the equatorial regions where giant plumes are stretched into a long wave pattern. Proceeding north of the equator, cirrus-like clouds are shredded by winds reaching speeds of up to 400 miles per hour, and more pinpoint-like thunderheads are visible. Although some of the famous belt and zone structure of Jupiter's atmosphere is washed out when viewed at this wavelength, the relatively thin North Temperate Belt shows up quite nicely, as does a series of waves just north of the belt. The north polar region of Jupiter in

  8. The First Russian Orbit-Borne Scatterometer: Numerical Simulation

    Science.gov (United States)

    Karaev, V. Yu.; Panfilova, M. A.; Titchenko, Yu. A.; Meshkov, E. M.; Balandina, G. N.; Kuznetsov, Yu. V.; Shlaferov, A. L.

    2016-04-01

    We have chosen a "SeaWinds" scatterometer with an orbital altitude of about 800 km as a prototype of the first Russian orbital scatterometer. An involuntary decrease in the orbit altitude to 650 km made us choose between conservation of the initial swath width 1800 km or the incidence angles with the swath-width decrease to 1500 km. A wider swath width has the advantage of a better coverage of the world-ocean surface. However, it leads to an increase in the local incidence angles and, hence, a decrease in the reflected-signal power. As a result, the signalto-noise ratio decreases and an error in the wind velocity and direction reconstruction because of the equipment noise increases. The error of the wind-velocity vector reconstruction for the same drive and antenna is the choice criterion. During the study, the mathematical model of the scatterometer is developed, the numerical simulation for both swath widths is performed, the data are processed, and the reconstruction accuracies of the wind velocity and direction are compared. It is shown that the reconstruction accuracy can significantly be improved if the measurement for two polarizations is used. The results obtained also show that the wind velocity is sufficiently well reconstructed for both swaths, while the wind-direction reconstruction accuracy in the case of a wider swath is worse than that required by the technical specifications for the scatterometer. Therefore, the swath width of the new scatterometer should be 1500 km.

  9. Family of Orbiters

    Science.gov (United States)

    2008-01-01

    This image shows the paths of three spacecraft currently in orbit around Mars, as well as the path by which NASA's Phoenix Mars Lander will approach and land on the planet. The t-shaped crosses show where the orbiters will be when Phoenix enters the atmosphere, while the x-shaped crosses show their location at landing time. All three orbiters, NASA's Mars Reconnaissance Orbiter, NASA's Mars Odyssey and the European Space Agency's Mars Express, will be monitoring Phoenix during the final steps of its journey to the Red Planet. Phoenix will land just south of Mars's north polar ice cap.

  10. Global Geospace Science/Polar Plasma Laboratory: POLAR

    Science.gov (United States)

    1996-01-01

    The Global Geospace Science (GGS) Project is discussed as part of the International Solar-Terrestrial Physics (ISTP) Science Initiative. The objectives of Polar Plasma Laboratory (POLAR), one of the two spacecraft to be used by the Project to fill critical gaps in the scientific understanding of solar and plasma physics, are outlined. POLAR Laboratory is described, along with POLAR instrumentation, support subsystems, and orbits. Launch vehicle and injection into orbit are also addressed.

  11. LLOFX earth orbit to lunar orbit delta V estimation program user and technical documentation

    Science.gov (United States)

    1988-01-01

    The LLOFX computer program calculates in-plane trajectories from an Earth-orbiting space station to Lunar orbit in such a way that the journey requires only two delta V burns (one to leave Earth circular orbit and one to circularize into Lunar orbit). The program requires the user to supply the Space Station altitude and Lunar orbit altitude (in km above the surface), and the desired time of flight for the transfer (in hours). It then determines and displays the trans-Lunar injection (TLI) delta V required to achieve the transfer, the Lunar orbit insertion (LOI) delta V required to circularize the orbit around the Moon, the actual time of flight, and whether the transfer orbit is elliptical or hyperbolic. Return information is also displayed. Finally, a plot of the transfer orbit is displayed.

  12. The Apsidal Precession for Low Earth Sun Synchronized Orbits

    Directory of Open Access Journals (Sweden)

    Shkelzen Cakaj

    2015-09-01

    Full Text Available By nodal regression and apsidal precession, the Earth flattering at satellite low Earth orbits (LEO is manifested. Nodal regression refers to the shift of the orbit’s line of nodes over time as Earth revolves around the Sun. Nodal regression is orbit feature utilized for circular orbits to be Sun synchronized. A sun¬-synchronized orbit lies in a plane that maintains a fixed angle with respect to the Earth-Sun direction. In the low Earth Sun synchronized circular orbits are suited the satellites that accomplish their photo imagery missions. Nodal regression depends on orbital altitude and orbital inclination angle. For the respective orbital altitudes the inclination window for the Sun synchronization to be attained is determined. The apsidal precession represents major axis shift, respectively the argument of perigee deviation. The apsidal precession simulation, for inclination window of sun synchronized orbital altitudes, is provided through this paper.

  13. 含Rashba自旋轨道耦合效应的非均匀量子线的极化输运性质%Spin-polarized transport in a nonuniform quantum wire with Rashba spin-orbit coupling

    Institute of Scientific and Technical Information of China (English)

    徐中辉; 肖贤波

    2012-01-01

    The spin-polarized electron transport for a narrow-wide- narrow (NWN) quantum wire under the modulation of Rashba spin-orbit coupling (SOC) is investigated via the spin-resolved lattice Green function method. The influence of both the structure of the quantum wire and the interference between different pairs of subbands on the spin polarized electron transport is taken into account simultaneously. It is found that a very large vertical spin-polarized current can be generated by the SOC-induced effective magnetic field at the structure-induced Fano resonance. Furthermore, the magnitude of the spin polarization can be tuned by the Rashba SOC strength and structural parameters. Those results may provide an effective way to design a spin filter device without containing any magnetic materials or applying a magnetic field.%采用递归格林函数法研究了含Rashba自旋轨道耦合(spin-orbit coupling,SOC)的窄-宽-窄形量子线的自旋极化输运性质.同时考虑了体系的结构和不同Rashba子带的混合对电子输运性质的影响,结果表明当电子的入射能量处在结构引起的Fano共振点时,能在出射端电极得到极化率较大的自旋极化电流,而且其大小可由自旋轨道耦合强度及系统的结构参数共同调节.这些效应说明所研究的体系也许能用来设计自旋过滤器件.

  14. Cerebrovascular stroke at high altitude

    International Nuclear Information System (INIS)

    Objective: To asses the high altitude as a risk factor for cerebrovascular stroke in people residing at a height greater than 15,000 feet above sea level. Results: Ten patients suffered from stroke at high altitude while just one case had stroke in indexed age group at lower heights (p-value<0.05). Relative risk was 10 times greater at high altitude. Conclusion: High altitude is a risk factor for stroke in persons residing at altitudes of over 15, 000 ft. (author)

  15. Dynamic Mission Modeling and Simulation: Application of Micro-Vacuum Arc Thrusters and Frozen Orbits

    Science.gov (United States)

    Suaris, Therese

    The dynamic mission modeling and simulation of scenarios around the Earth, Moon, and libration points are used to explore the application of the Vacuum Arc Thruster and frozen orbits for future space exploration missions. The Micro-Vacuum Arc Thruster (microVAT) is a propulsion system that uses an arc to evaporate solid cathode material. The propulsion system is compatible for nano-satellite applications due to its low operating voltage, low mass, and its simplicity to be integrated into the spacecraft operating system. The microVAT experimental performance values were used to baseline the numerical thruster model for the space mission operational scenarios. The simulation results were used analyze and make recommendations on the performance parameters that are required for maneuvers and interplanetary trajectories for space exploration missions. In addition, the analytical derivation and numerical analysis of Earth-based frozen orbits are used to baseline the low-altitude, frozen orbits. A high resolution in order and degree lunar gravity model and third-body perturbations due to the Earth and Sun are included in the detailed simulation. The time evolution of the classical frozen orbital conditions is calculated by numerically propagating the orbits in an environment where all the perturbations are included. The behaviour and evolution pattern of the orbital elements are used to baseline a set of numerical quasi-frozen conditions for a series of low-altitude, polar orbits. The numerically integrated results for a family of polar frozen orbits provide insight into the predictive behaviour pattern and evolution of the orbital elements that can be extended to any given set of initial conditions and requirements. It is shown that these results are not a fixed point solution that is calculated for a selective set of perturbations, but rather the numerical model can be used to determine a set of conditions and orbital elements to satisfy a given set of mission

  16. Cloud Altitude Determination of Overshooting Tops in Severe Thunderstorms

    Science.gov (United States)

    Goldberg, R.; Magee, N. B.

    2011-12-01

    The maximum heights of deep convective clouds and overshooting tops have been analyzed and compared using a combination of space and ground-based measurement systems. Deeply convective cumulonimbus clouds are capable of reaching and penetrating the tropopause. The portions of convective clouds that extend into the stratosphere are known as overshooting tops. Instances of tornado onset have been observed to match or slightly lag the timing of maximum cloud-top altitudes. In addition, precise forecasting and measurement of convective cloud-top heights are of critical importance to the safety and efficiency of commercial aviation flight routings. This study included the use of data from three NASA A-Train satellites, 88-D and TDWR Doppler radar, NAM modeling output, and direct visual sightings. The three polar-orbiting satellites included Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, and Aqua. CALIPSO and CloudSat return a vertical profile of microphysical parameters as their near-nadir beams intersect clouds. CALIPSO uses a lidar instrument (CALIOP), operating at 532 and 1064 nm, that is capable of detecting aerosol and small cloud particles. CloudSat uses a radar system called Cloud Profiling Radar (CPR), operating at 94 GHz (3.2 mm), that can penetrate thicker clouds, including those with precipitation. The Moderate Resolution Imaging Spectroradiometer (MODIS) on board Aqua provided a 250m resolution map view that permitted identification of the unique texture of overshooting tops. Satellite data and ground-based Doppler radar were co-located and used to compare cloud-top and echo-top measurements and products. In addition to co-located observational data, North American Mesoscale (NAM) model output with maximum 6-hour lead time was analyzed for convective cloud top forecasts. Finally, direct sightings of cloud tops were made at the time of CALIPSO overpasses of New Jersey. Using a surveyor's transit, the angle from the

  17. Polar Satcom System and Related Method

    Science.gov (United States)

    Mitchell, James P. (Inventor)

    2016-01-01

    A system and method for communication relay via a repeater platform satellite vehicle to a near surface station in the Polar Region is disclosed. A preferred embodiment receives a plurality of positioning and content data from a plurality of constellations of Geosynchronous Equatorial Orbit (GEO) Satellite Vehicles (SAT). Additionally, the system receives a plurality of position, time and altitude data from constellations of available repeater platform (RP) SATs. The system receives a request for content from a near surface station located in an area lacking adequate line-of-sight to the GEO based signal. The system aligns antenna elements onboard the desired RP SATs to amplify and relay the GEO based signal toward the near surface station and vice versa. Additionally, the system commands directional antenna elements onboard the station to send and receive the relayed signal making the GEO based content available to the near surface station.

  18. High Altitude Emissions

    Science.gov (United States)

    Bulzan, Dan

    2007-01-01

    An overview of emissions related research being conducted as part of the Fundamental Aeronautics Supersonics Project is presented. The overview includes project objectives, milestones, and descriptions of major research areas. The overview also includes information on the emissions research being conducted under NASA Research Announcements. Technical challenges include: 1) Environmental impact of supersonic cruise emissions is greater due to higher flight altitudes which makes emissions reduction increasingly important. 2) Accurate prediction tools to enable combustor designs that reduce emissions at supersonic cruise are needed as well as intelligent systems to minimize emissions. 3) Combustor operating conditions at supersonic cruise are different than at subsonic cruise since inlet fuel and air temperatures are considerably increased.

  19. Objects orbiting the Earth in deep resonance

    OpenAIRE

    J. C. Sampaio; Wnuk, E.; de Moraes, R. Vilhena; S. S. Fernandes

    2012-01-01

    The increasing number of objects orbiting the Earth justifies the great attention and interest in the observation, spacecraft protection and collision avoidance. These studies involve different disturbances and resonances in the orbital motions of these objects distributed by the distinct altitudes. In this work, the TLE (Two-Line Elements) of the NORAD are studied observing the resonant period of the objects orbiting the Earth and the main resonance in the LEO region. The time behavior of th...

  20. Time-variability of Polar Winter Snow Clouds on Mars

    Science.gov (United States)

    Hayne, P. O.; Kass, D. M.; Kleinboehl, A.; Schofield, J. T.; McCleese, D. J.

    2015-12-01

    Carbon dioxide snow clouds are known to occur in the polar regions on Mars during the long polar night. Earlier studies have shown that a substantial fraction (up to ~20%) of the seasonal ice caps of Mars can be deposited as CO2 snowfall. The presence of optically thick clouds can also strongly influence the polar energy balance, by scattering thermal radiation emitted by the surface and lower atmosphere. Furthermore, snow deposition is likely to affect the surface morphology and subsequent evolution of the seasonal caps. Therefore, both the spatial distribution and time variability of polar snow clouds are important for understanding their influence on the Martian CO2cycle and climate. However, previous investigations have suffered from relatively coarse time resolution (typically days), coarse or incomplete spatial coverage, or both. Here we report results of a dedicated campaign by the Mars Climate Sounder (MCS) onboard the Mars Reconnaissance Orbiter, to observe polar CO2 clouds with an unprecedented time-resolution within the same spatial region. By scanning the MCS field of view, we acquired observations directly over the north pole for every ~2hr orbit over the course of several days. This was repeated during two separate periods in northern winter. The 2 hr sampling frequency enables the detailed study of cloud evolution. These observations were also compared to a cloud-free, control region just off the pole, which was sampled in the same way. Results from this experiment show that the north polar CO2 clouds are dynamic, and appear to follow a consistent pattern: Beginning with a relatively clear atmosphere, the cloud rapidly grows to ~25 - 30 km altitude in future research, enabled by these unique observations. Part of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  1. HAMP – the microwave package on the High Altitude and LOng range research aircraft HALO

    Directory of Open Access Journals (Sweden)

    M. Mech

    2014-05-01

    Full Text Available An advanced package of microwave remote sensing instrumentation has been developed for the operation on the new German High Altitude LOng range research aircraft (HALO. The HALO Microwave Package, HAMP, consists of two nadir looking instruments: a cloud radar at 36 GHz and a suite of passive microwave radiometers with 26 frequencies in different bands between 22.24 and 183.31 ± 12.5 GHz. We present a description of HAMP's instrumentation together with an illustration of its potential. To demonstrate this potential synthetic measurements for the implemented passive microwave frequencies and the cloud radar based on cloud resolving and radiative transfer model calculations were performed. These illustrate the advantage of HAMP's chosen frequency coverage, which allows for improved detection of hydrometeors both via the emission and scattering of radiation. Regression algorithms compare HAMP retrieval with standard satellite instruments from polar orbiters and show its advantages particularly for the lower atmosphere with a reduced root mean square error by 5 and 15% for temperature and humidity, respectively. HAMP's main advantage is the high spatial resolution of about 1 km which is illustrated by first measurements from test flights. Together these qualities make it an exciting tool for gaining better understanding of cloud processes, testing retrieval algorithms, defining future satellite instrument specifications, and validating platforms after they have been placed in orbit.

  2. HAMP – the microwave package on the High Altitude and LOng range research aircraft (HALO

    Directory of Open Access Journals (Sweden)

    M. Mech

    2014-12-01

    Full Text Available An advanced package of microwave remote sensing instrumentation has been developed for the operation on the new German High Altitude LOng range research aircraft (HALO. The HALO Microwave Package, HAMP, consists of two nadir-looking instruments: a cloud radar at 36 GHz and a suite of passive microwave radiometers with 26 frequencies in different bands between 22.24 and 183.31 ± 12.5 GHz. We present a description of HAMP's instrumentation together with an illustration of its potential. To demonstrate this potential, synthetic measurements for the implemented passive microwave frequencies and the cloud radar based on cloud-resolving and radiative transfer model calculations were performed. These illustrate the advantage of HAMP's chosen frequency coverage, which allows for improved detection of hydrometeors both via the emission and scattering of radiation. Regression algorithms compare HAMP retrieval with standard satellite instruments from polar orbiters and show its advantages particularly for the lower atmosphere with a root-mean-square error reduced by 5 and 15% for temperature and humidity, respectively. HAMP's main advantage is the high spatial resolution of about 1 km, which is illustrated by first measurements from test flights. Together these qualities make it an exciting tool for gaining a better understanding of cloud processes, testing retrieval algorithms, defining future satellite instrument specifications, and validating platforms after they have been placed in orbit.

  3. Induced spin-accumulation and spin-polarization in a quantum-dot ring by using magnetic quantum dots and Rashba spin-orbit effect

    Energy Technology Data Exchange (ETDEWEB)

    Eslami, L., E-mail: Leslami@iust.ac.ir; Faizabadi, E. [School of Physics, Iran University of Science and Technology, Tehran 16846 (Iran, Islamic Republic of)

    2014-05-28

    The effect of magnetic contacts on spin-dependent electron transport and spin-accumulation in a quantum ring, which is threaded by a magnetic flux, is studied. The quantum ring is made up of four quantum dots, where two of them possess magnetic structure and other ones are subjected to the Rashba spin-orbit coupling. The magnetic quantum dots, referred to as magnetic quantum contacts, are connected to two external leads. Two different configurations of magnetic moments of the quantum contacts are considered; the parallel and the anti-parallel ones. When the magnetic moments are parallel, the degeneracy between the transmission coefficients of spin-up and spin-down electrons is lifted and the system can be adjusted to operate as a spin-filter. In addition, the accumulation of spin-up and spin-down electrons in non-magnetic quantum dots are different in the case of parallel magnetic moments. When the intra-dot Coulomb interaction is taken into account, we find that the electron interactions participate in separation between the accumulations of electrons with different spin directions in non-magnetic quantum dots. Furthermore, the spin-accumulation in non-magnetic quantum dots can be tuned in the both parallel and anti-parallel magnetic moments by adjusting the Rashba spin-orbit strength and the magnetic flux. Thus, the quantum ring with magnetic quantum contacts could be utilized to create tunable local magnetic moments which can be used in designing optimized nanodevices.

  4. Earth Orbiting Support Systems for commercial low Earth orbit data relay: Assessing architectures through tradespace exploration

    Science.gov (United States)

    Palermo, Gianluca; Golkar, Alessandro; Gaudenzi, Paolo

    2015-06-01

    As small satellites and Sun Synchronous Earth Observation systems are assuming an increased role in nowadays space activities, including commercial investments, it is of interest to assess how infrastructures could be developed to support the development of such systems and other spacecraft that could benefit from having a data relay service in Low Earth Orbit (LEO), as opposed to traditional Geostationary relays. This paper presents a tradespace exploration study of the architecture of such LEO commercial satellite data relay systems, here defined as Earth Orbiting Support Systems (EOSS). The paper proposes a methodology to formulate architectural decisions for EOSS constellations, and enumerate the corresponding tradespace of feasible architectures. Evaluation metrics are proposed to measure benefits and costs of architectures; lastly, a multicriteria Pareto criterion is used to downselect optimal architectures for subsequent analysis. The methodology is applied to two case studies for a set of 30 and 100 customer-spacecraft respectively, representing potential markets for LEO services in Exploration, Earth Observation, Science, and CubeSats. Pareto analysis shows how increased performance of the constellation is always achieved by an increased node size, as measured by the gain of the communications antenna mounted on EOSS spacecraft. On the other hand, nonlinear trends in optimal orbital altitude, number of satellites per plane, and number of orbital planes, are found in both cases. An upward trend in individual node memory capacity is found, although never exceeding 256 Gbits of onboard memory for both cases that have been considered, assuming the availability of a polar ground station for EOSS data downlink. System architects can use the proposed methodology to identify optimal EOSS constellations for a given service pricing strategy and customer target, thus identifying alternatives for selection by decision makers.

  5. RHIC Polarized proton operation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D' Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R,; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; J.; Severino, F.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J. Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.

    2011-03-28

    The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above

  6. RHIC Polarized proton operation

    International Nuclear Information System (INIS)

    The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP4. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above injection

  7. Venus Altitude Cycling Balloon Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The ISTAR Group ( IG) and team mate Thin Red Line Aerospace (TRLA) propose a Venus altitude cycling balloon (Venus ACB), an innovative superpressure balloon...

  8. Coronary heart disease at altitude.

    OpenAIRE

    Alexander, J K

    1994-01-01

    In the past, it has been assumed that some basic physiologic responses to altitude, exposure in coronary patients are comparable to those in normal young subjects. In fact there are similar changes in sympathetic activation, heart rate, and blood pressure early after ascent, with decrements in plasma volume, cardiac output, and stroke volume as acclimatization proceeds. These responses are described, and experience with coronary patients is reviewed. During the 1st 2 to 3 days at altitude, co...

  9. High-altitude pulmonary hypertension

    OpenAIRE

    X-Q. Xu; Z-C. Jing

    2009-01-01

    High-altitude pulmonary hypertension (HAPH) is a specific disease affecting populations that live at high elevations. The prevalence of HAPH among those residing at high altitudes needs to be further defined. Whereas reduction in nitric oxide production may be one mechanism for the development of HAPH, the roles of endothelin-1 and prostaglandin I2 pathways in the pathogenesis of HAPH deserve further study. Although some studies have suggested that genetic factors contribute to the pathogenes...

  10. Orbital pseudotumor

    Science.gov (United States)

    ... Names Idiopathic orbital inflammatory syndrome (IOIS) Images Skull anatomy References Goodlick TA, Kay MD, Glaser JS, Tse DT, Chang WJ. Orbital disease and neuro-ophthalmology. In: Tasman W, Jaeger EA, eds. Duane’s ...

  11. Quark Orbital Angular Momentum

    Science.gov (United States)

    Burkardt, Matthias

    2016-06-01

    Generalized parton distributions provide information on the distribution of quarks in impact parameter space. For transversely polarized nucleons, these impact parameter distributions are transversely distorted and this deviation from axial symmetry leads on average to a net transverse force from the spectators on the active quark in a DIS experiment. This force when acting along the whole trajectory of the active quark leads to transverse single-spin asymmetries. For a longitudinally polarized nucleon target, the transverse force implies a torque acting on the quark orbital angular momentum (OAM). The resulting change in OAM as the quark leaves the target equals the difference between the Jaffe-Manohar and Ji OAMs.

  12. Quark Orbital Angular Momentum

    Science.gov (United States)

    Burkardt, Matthias

    2016-03-01

    Generalized parton distributions provide information on the distribution of quarks in impact parameter space. For transversely polarized nucleons, these impact parameter distributions are transversely distorted and this deviation from axial symmetry leads on average to a net transverse force from the spectators on the active quark in a DIS experiment. This force when acting along the whole trajectory of the active quark leads to transverse single-spin asymmetries. For a longitudinally polarized nucleon target, the transverse force implies a torque acting on the quark orbital angular momentum (OAM). The resulting change in OAM as the quark leaves the target equals the difference between the Jaffe-Manohar and Ji OAMs.

  13. Determining polar ionospheric electrojet currents from Swarm satellite constellation magnetic data

    Science.gov (United States)

    Aakjær, Cecilie Drost; Olsen, Nils; Finlay, Christopher C.

    2016-08-01

    We determine the strength and location of the ionospheric currents responsible for the polar electrojets from magnetic data collected by the Swarm satellite constellation on an orbit-by-orbit basis. The ionospheric currents are modelled using a simple, yet robust, method by a series of line currents at 110 km altitude (corresponding to the ionospheric E-layer) perpendicular to the satellite orbit, separated by 1° (about 113 km). We assess the reliability of our method, with the aim of a possible near-real-time application. A study of the effect of different regularization methods is therefore carried out. An L_1 model regularization of the second-order spatial differences, and robust treatment of the data (to account for non-Gaussian error distributions), yields the most encouraging results. We apply our approach to two three-weekly data periods in March 2014 (geomagnetic quiet conditions) and March 2015 (more disturbed conditions), respectively. Our orbit-by-orbit approach also allows the temporal evolution of the polar electrojets to be investigated. We find remarkable agreement of the ionospheric activity in Northern and Southern polar regions, with correlation exceeding 0.9 for periods longer than two days. Reliability of the approach is shown by three key results: (1) a common regularization parameter for all orbits with enough data coverage, (2) 0.95 squared coherence with the Auroral Electrojet index, and (3) 0.97 squared coherence is found between the side-by-side flying satellites, Alpha and Charlie, indicating a method invariant to small changes in data input. All these results indicate a possible automated near-real-time application.

  14. Resonant Orbital Dynamics in LEO Region: Space Debris in Focus

    OpenAIRE

    J. C. Sampaio; E. Wnuk; R. Vilhena de Moraes; S. S. Fernandes

    2014-01-01

    The increasing number of objects orbiting the earth justifies the great attention and interest in the observation, spacecraft protection, and collision avoidance. These studies involve different disturbances and resonances in the orbital motions of these objects distributed by the distinct altitudes. In this work, objects in resonant orbital motions are studied in low earth orbits. Using the two-line elements (TLE) of the NORAD, resonant angles and resonant periods associated with real motion...

  15. High-altitude pulmonary hypertension

    Directory of Open Access Journals (Sweden)

    X-Q. Xu

    2009-03-01

    Full Text Available High-altitude pulmonary hypertension (HAPH is a specific disease affecting populations that live at high elevations. The prevalence of HAPH among those residing at high altitudes needs to be further defined. Whereas reduction in nitric oxide production may be one mechanism for the development of HAPH, the roles of endothelin-1 and prostaglandin I2 pathways in the pathogenesis of HAPH deserve further study. Although some studies have suggested that genetic factors contribute to the pathogenesis of HAPH, data published to date are insufficient for the identification of a significant number of gene polymorphims in HAPH. The clinical presentation of HAPH is nonspecific. Exertional dyspnoea is the most common symptom and signs related to right heart failure are common in late stages of HAPH. Echocardiography is the most useful screening tool and right heart catheterisation is the gold standard for the diagnosis of HAPH. The ideal management for HAPH is migration to lower altitudes. Phosphodiesterase 5 is an attractive drug target for the treatment of HAPH. In addition, acetazolamide is a promising therapeutic agent for high-altitude pulmonary hypertension. To date, no evidence has confirmed whether endothelin-receptor antagonists have efficacy in the treatment of high-altitude pulmonary hypertension.

  16. SPECS: Orbital debris removal

    Science.gov (United States)

    1991-01-01

    The debris problem has reached a stage at which the risk to satellites and spacecraft has become substantial in low Earth orbit (LEO). This research discovered that small particles posed little threat to spacecraft because shielding can effectively prevent these particles from damaging the spacecraft. The research also showed that, even though collision with a large piece of debris could destroy the spacecraft, the large pieces of debris pose little danger because they can be tracked and the spacecraft can be maneuvered away from these pieces. Additionally, there are many current designs to capture and remove large debris particles from the space environment. From this analysis, it was decided to concentrate on the removal of medium-sized orbital debris, that is, those pieces ranging from 1 cm to 50 cm in size. The current design incorporates a transfer vehicle and a netting vehicle to capture the medium-sized debris. The system is based near an operational space station located at 28.5 deg inclination and 400 km altitude. The system uses ground-based tracking to determine the location of a satellite breakup or debris cloud. These data are uploaded to the transfer vehicle, which proceeds to rendezvous with the debris at a lower altitude parking orbit. Next, the netting vehicle is deployed, tracks the targeted debris, and captures it. After expending the available nets, the netting vehicle returns to the transfer vehicle for a new netting module and continues to capture more debris in the target area. Once all the netting modules are expended, the transfer vehicle returns to the space station's orbit where it is resupplied with new netting modules from a space shuttle load. The new modules are launched by the shuttle from the ground and the expended modules are taken back to Earth for removal of the captured debris, refueling, and repacking of the nets. Once the netting modules are refurbished, they are taken back into orbit for reuse. In a typical mission, the

  17. Hormonal Changes Under Altitude Stress

    Directory of Open Access Journals (Sweden)

    H.D Brahmachari

    1977-04-01

    Full Text Available The separate effects of exposure for six hours to cold (8 degree Celsius, hypoxia (4267 m. and simulated altitude (8 degree Celsius at 4267 m.have been studied on ten human subjects in a decompression chamber, with respect to the changes in blood cortisol, ADH and urinary catecholamines. Changes in blood cortisol, PBI, ADH urinary excretion of 17-keto steroids and urine volume have been recorded on another ten subjects on acute exposure to high altitude (3505 m.. Changes in the same parameters alongwith urinary testosterone level, have been recorded on another 20 subjects on prolonged exposure for two years to high altitude (3505 m.. The results have been discussed.

  18. Altitude precipitation gradient in Serbia

    Directory of Open Access Journals (Sweden)

    Živković Nenad M.

    2004-01-01

    Full Text Available Using average annual precipitations data for period 1961-90. from all rain gauges in Serbia, southern of Sava and Danube rivers, the map of altitude precipitations gradient is constructed. 59 regions homogeneous for relation X=f(H are obtained by regression analysis method (two-dimensional type, X precipitation height and H - altitude. Some new method are applied, some limitations are shown, some regularities are found in disposition of precipitation growth and it is indicated on practical application of this method in physico-geographical research.

  19. ORION: A Supersynchronous Transfer Orbit mission

    Science.gov (United States)

    Walters, I. M.; Baker, J. F.; Shurmer, I. M.

    1995-01-01

    ORION F1 was launched on 29th November 1994 on an Atlas IIA launch vehicle. It was designed, built and delivered in-orbit by Matra Marconi Space Systems Plc and was handed over to ORION Satellite Corporation on 20th January 1995 at its on-station longitude of 37.5 deg W. The mission differed significantly from that of any other geostationary communications satellite in that the Transfer Orbit apogee altitude of 123,507 km was over three times geosynchronous (GEO) altitude and one third of the way to the moon. The SuperSynchronous Transfer Orbit (SSTO) mission is significantly different from the standard Geostationary Transfer Orbit (GTO)mission in a number of ways. This paper discusses the essential features of the mission design through its evolution since 1987 and the details of the highly successful mission itself including a detailed account of the attitude determination achieved using the Galileo Earth and Sun Sensor (ESS).

  20. ORION: A Supersynchronous Transfer Orbit mission

    Science.gov (United States)

    Walters, I. M.; Baker, J. F.; Shurmer, I. M.

    1995-05-01

    ORION F1 was launched on 29th November 1994 on an Atlas IIA launch vehicle. It was designed, built and delivered in-orbit by Matra Marconi Space Systems Plc and was handed over to ORION Satellite Corporation on 20th January 1995 at its on-station longitude of 37.5 deg W. The mission differed significantly from that of any other geostationary communications satellite in that the Transfer Orbit apogee altitude of 123,507 km was over three times geosynchronous (GEO) altitude and one third of the way to the moon. The SuperSynchronous Transfer Orbit (SSTO) mission is significantly different from the standard Geostationary Transfer Orbit (GTO)mission in a number of ways. This paper discusses the essential features of the mission design through its evolution since 1987 and the details of the highly successful mission itself including a detailed account of the attitude determination achieved using the Galileo Earth and Sun Sensor (ESS).

  1. SHARP: Subsonic High Altitude Research Platform

    Science.gov (United States)

    Beals, Todd; Burton, Craig; Cabatan, Aileen; Hermano, Christine; Jones, Tom; Lee, Susan; Radloff, Brian

    1991-01-01

    The Universities Space Research Association is sponsoring an undergraduate program which is geared to designing an aircraft that can study the ozone layer at the equator. This aircraft must be able to satisfy four mission profiles. Mission one is a polar mission that ranges from Chile to the South Pole and back to Chile, a total range of 6000 n.mi. at 100,000 ft with a 2500 lb payload. The second mission is also a polar mission, with an altitude of 70,000 ft and an increased payload of 4000 lbs. For the third mission, the aircraft will takeoff at NASA Ames, cruise at 100,000 ft carrying a 2500 lb payload, and land at Puerto Montt, Chile. The final mission requires the aircraft to take off at NASA Ames, cruise at 100,000 ft with a 1000 lb payload, make an excursion to 120,000 ft, and land at Howard AFB, Panama. Three missions require that a subsonic Mach number be maintained due to constraints imposed by the air sampling equipment. The aircraft need not be manned for all four missions. Three aircraft configurations have been determined to be the most suitable for meeting the above requirements. In the event that a requirement cannot be obtained within the given constraints, recommendations for proposal modifications are given.

  2. A Wide Field Auroral Imager (WFAI for low Earth orbit missions

    Directory of Open Access Journals (Sweden)

    N. P. Bannister

    2007-03-01

    Full Text Available A comprehensive understanding of the solar wind interaction with Earth's coupled magnetosphere-ionosphere system requires an ability to observe the charged particle environment and auroral activity from the same platform, generating particle and photon image data which are matched in time and location. While unambiguous identification of the particles giving rise to the aurora requires a Low Earth Orbit satellite, obtaining adequate spatial coverage of aurorae with the relatively limited field of view of current space bourne auroral imaging systems requires much higher orbits. A goal for future satellite missions, therefore, is the development of compact, wide field-of-view optics permitting high spatial and temporal resolution ultraviolet imaging of the aurora from small spacecraft in low polar orbit. Microchannel plate optics offer a method of achieving the required performance. We describe a new, compact instrument design which can observe a wide field-of-view with the required spatial resolution. We report the focusing of 121.6 nm radiation using a spherically-slumped, square-pore microchannel plate with a focal length of 32 mm and an F number of 0.7. Measurements are compared with detailed ray-trace simulations of imaging performance. The angular resolution is 2.7±0.2° for the prototype, corresponding to a footprint ~33 km in diameter for an aurora altitude of 110 km and a spacecraft altitude of 800 km. In preliminary analysis, a more recent optic has demonstrated a full width at half maximum of 5.0±0.3 arcminutes, corresponding to a footprint of ~1 km from the same spacecraft altitude. We further report the imaging properties of a convex microchannel plate detector with planar resistive anode readout; this detector, whose active surface has a radius of curvature of only 100 mm, is shown to meet the spatial resolution and sensitivity requirements of the new wide field auroral imager (WFAI.

  3. Helioseismology with Solar Orbiter

    CERN Document Server

    Löptien, Björn; Gizon, Laurent; Schou, Jesper; Appourchaux, Thierry; Rodríguez, Julián Blanco; Cally, Paul S; Dominguez-Tagle, Carlos; Gandorfer, Achim; Hill, Frank; Hirzberger, Johann; Scherrer, Philip H; Solanki, Sami K

    2014-01-01

    The Solar Orbiter mission, to be launched in July 2017, will carry a suite of remote sensing and in-situ instruments, including the Polarimetric and Helioseismic Imager (PHI). PHI will deliver high-cadence images of the Sun in intensity and Doppler velocity suitable for carrying out novel helioseismic studies. The orbit of the Solar Orbiter spacecraft will reach a solar latitude of up to 21 deg (up to 34 deg by the end of the extended mission) and thus will enable the first local helioseismology studies of the polar regions. Here we consider an array of science objectives to be addressed by helioseismology within the baseline telemetry allocation (51 Gbit per orbit, current baseline) and within the science observing windows (baseline 3 x 10 days per orbit). A particularly important objective is the measurement of large-scale flows at high latitudes (rotation and meridional flow), which are largely unknown but play an important role in flux transport dynamos. The full range of Earth-Sun-spacecraft angles provi...

  4. Orbital velocity

    CERN Document Server

    Modestino, Giuseppina

    2016-01-01

    The trajectory and the orbital velocity are determined for an object moving in a gravitational system, in terms of fundamental and independent variables. In particular, considering a path on equipotential line, the elliptical orbit is naturally traced, verifying evidently the keplerian laws. The case of the planets of the solar system is presented.

  5. Gamma rays in L-B coordinates at CORONAS-I altitude

    Directory of Open Access Journals (Sweden)

    I. N. Myagkova

    2005-09-01

    Full Text Available We present here observations of gamma rays in the energy range between 3.0 and 8.3 MeV gathered by the SONG instrument aboard low-altitude polar-orbiting satellite CORONAS-I throughout the period March-June 1994. We concentrate on the emissions related to the trapped particles and organize CORONAS-I measurements in the magnetic L–B coordinate system. The spatial distribution of the average gamma-ray counts reveals that the most intense fluxes were observed under the inner radiation belt, at L<2, and that they are exclusively confined into the region of stably trapped particles, where daughter gamma rays could result from the interactions within the spacecraft and instrumental matter. In the outer radiation zone (L~4, the enhanced gamma radiation, also detected outside the stably trapping region, shows pronounced longitudinal variations. The observed eastward increase in the gamma-ray count rate suggests quasi-traped energetic (megavolt electrons as a source of the gamma rays both in the upper atmosphere and in the satellite matter, most likely, through the bremsstrahlung process in the studied energy domain. Keywords. Magnetospheric physics (Energetic particles, precipitating; Energetic particles, trapped; Magnetosphereionosphere interactions

  6. Testing the magnetotail configuration based on observations of low-altitude isotropic boundaries during quiet times

    Science.gov (United States)

    Ilie, R.; Ganushkina, N.; Toth, G.; Dubyagin, S.; Liemohn, M. W.

    2015-12-01

    We investigate the configuration of the geomagnetic field on the nightside magnetosphere during a quiet time interval based on National Oceanic and Atmospheric Administration Polar Orbiting Environment Satellites Medium Energy Proton and Electron Detector (NOAA/POES MEPED) measurements in combination with numerical simulations of the global terrestrial magnetosphere using the Space Weather Modeling Framework. Measurements from the NOAA/POES MEPED low-altitude data sets provide the locations of isotropic boundaries; those are used to extract information regarding the field structure in the source regions in the magnetosphere. In order to evaluate adiabaticity and mapping accuracy, which is mainly controlled by the ratio between the radius of curvature and the particle's Larmor radius, we tested the threshold condition for strong pitch angle scattering based on the MHD magnetic field solution. The magnetic field configuration is represented by the model with high accuracy, as suggested by the high correlation coefficients and very low normalized root-mean-square errors between the observed and the modeled magnetic field. The scattering criterion, based on the values of k=Rcρ ratio at the crossings of magnetic field lines, associated with isotropic boundaries, with the minimum B surface, predicts a critical value of kCR˜33. This means that, in the absence of other scattering mechanisms, the strong pitch angle scattering takes place whenever the Larmor radius is ˜33 times smaller than the radius of curvature of the magnetic field, as predicted by the Space Weather Modeling Framework.

  7. Sleep and Breathing at High Altitude.

    Science.gov (United States)

    Wickramasinghe, Himanshu; Anholm, James D.

    1999-01-01

    Sleep at high altitude is characterized by poor subjective quality, increased awakenings, frequent brief arousals, marked nocturnal hypoxemia, and periodic breathing. A change in sleep architecture with an increase in light sleep and decreasing slow-wave and REM sleep have been demonstrated. Periodic breathing with central apnea is almost universally seen amongst sojourners to high altitude, although it is far less common in long-standing high altitude dwellers. Hypobaric hypoxia in concert with periodic breathing appears to be the principal cause of sleep disruption at altitude. Increased sleep fragmentation accounts for the poor sleep quality and may account for some of the worsened daytime performance at high altitude. Hypoxic sleep disruption contributes to the symptoms of acute mountain sickness. Hypoxemia at high altitude is most severe during sleep. Acetazolamide improves sleep, AMS symptoms, and hypoxemia at high altitude. Low doses of a short acting benzodiazepine (temazepam) may also be useful in improving sleep in high altitude. PMID:11898114

  8. Altitude, Acute Mountain Sickness and Headache

    Science.gov (United States)

    ... Follow us on Instagram DONATE TODAY Altitude, Acute Mountain Sickness and Headache Abuse, Maltreatment, and PTSD and Their Relationship to Migraine Altitude, Acute Mountain Sickness and Headache Alcohol and Migraine Anxiety and ...

  9. Nonlinear filtering for autonomous navigation of spacecraft in highly elliptical orbit

    Science.gov (United States)

    Vigneron, Adam C.; de Ruiter, Anton H. J.; Burlton, Bruce V.; Soh, Warren K. H.

    2016-05-01

    In support of Canada's proposed Polar Communication and Weather mission, this study examined the accuracy to which GPS-based autonomous navigation might be realized for spacecraft in a Molniya orbit. A navigation algorithm based on the Extended Kalman Filter was demonstrated to achieve a three-dimensional root-mean-square accuracy of 58.9 m over a Molniya orbit with 500 km and 40,000 km perigee and apogee altitudes, respectively. Despite the inclusion of biased and non-white error models in the generated GPS pseudorange measurements - a first for navigation studies in this orbital regime - algorithms based on the Unscented Kalman Filter and the Cubature Kalman Filter were not found to improve this result; their benefits were eclipsed due to the accurate pseudorange measurements which were available during periods of highly nonlinear dynamics. This study revealed receiver clock bias error to be a significant source of navigation solution error. For reasons of geometry, the navigation algorithm is not able to differentiate between this error and a radial position error. A novel dual-mode dynamic clock model was proposed and implemented as a means to minimize receiver clock bias error over the entire orbital regime.

  10. Observing Mode Attitude Controller for the Lunar Reconnaissance Orbiter

    Science.gov (United States)

    Calhoun, Philip C.; Garrick, Joseph C.

    2007-01-01

    The Lunar Reconnaissance Orbiter (LRO) mission is the first of a series of lunar robotic spacecraft scheduled for launch in Fall 2008. LRO will spend at least one year in a low altitude polar orbit around the Moon, collecting lunar environment science and mapping data to enable future human exploration. The LRO employs a 3-axis stabilized attitude control system (ACS) whose primary control mode, the "Observing mode", provides Lunar Nadir, off-Nadir, and Inertial fine pointing for the science data collection and instrument calibration. The controller combines the capability of fine pointing with that of on-demand large angle full-sky attitude reorientation into a single ACS mode, providing simplicity of spacecraft operation as well as maximum flexibility for science data collection. A conventional suite of ACS components is employed in this mode to meet the pointing and control objectives. This paper describes the design and analysis of the primary LRO fine pointing and attitude re-orientation controller function, known as the "Observing mode" of the ACS subsystem. The control design utilizes quaternion feedback, augmented with a unique algorithm that ensures accurate Nadir tracking during large angle yaw maneuvers in the presence of high system momentum and/or maneuver rates. Results of system stability analysis and Monte Carlo simulations demonstrate that the observing mode controller can meet fine pointing and maneuver performance requirements.

  11. Cold Stress at High Altitudes

    Directory of Open Access Journals (Sweden)

    N. C. Majumdar

    1983-04-01

    Full Text Available The problem of cold at high altitudes has been analysed from a purely physical standpoint. It has been shown that Siple's Wind-Chill Index is not reliable because (i it does not make use of the well established principles governing the physical processes of heat transfer by convection and radiation, and (ii it assumes that the mean radiant temperature of the surroundings is the same as the ambient dry bulb temperature. A Cold Stress Index has been proposed which is likely to be a more reliable guide for assessing the climatic hazards of high altitude environments. The Index can be quickly estimated with the help of two nomograms devised for the purpose.

  12. Altitude Control Feasibility for a Seaweed Harvester

    OpenAIRE

    Gallieri, Marco; Ringwood, John

    2010-01-01

    In this paper, the feasibility of the altitude control of a seaweed harvester is examined. The harvesting system consists of a vessel and a suspended harvester device, the altitude of which is controlled by a winch. The goal of the control action is to maintain the harvester at a constant altitude with respect to the seabed profile. A control strategy is proposed, including a vessel motion feed-forward action, using a motion reference unit (MRU), and an altitude feedback ...

  13. Foreign body orbital cyst

    DEFF Research Database (Denmark)

    Yazdanfard, Younes; Heegard, Steffen; Fledelius, Hans C.;

    2001-01-01

    Ophthalmology, penetrating orbital injury, orbital foreign body, ultrasound, computed tomography (CT), histology......Ophthalmology, penetrating orbital injury, orbital foreign body, ultrasound, computed tomography (CT), histology...

  14. Small Mercury Relativity Orbiter

    Science.gov (United States)

    Bender, Peter L.; Vincent, Mark A.

    1989-01-01

    The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.

  15. Iridium: Global OTH data communications for high altitude scientific ballooning

    Science.gov (United States)

    Denney, A.

    beneficial points provided by the Iridium platform include pure global accessibility (as well as polar), cost effectiveness because it is available as a COTS (Commercially Off The Shelf) technology, reliability in that the equipment must operate in extreme conditions (near space), integration and development time into current systems must be minimized. As a bonus Motorola and NAL Research Corporation are developing SBD (Short Burst Data) into the Iridium network. This may lead the way to a global IP (Internet Protocol) node based ballooning platform. The Iridium satellite data modems employ the Iridium Low-Earth Orbit (LEO) satellite network. The scope of this paper is to introduce an OTH communications alternative, albeit not necessarily a primary one, to existing ballooning platforms using COTS based emerging technologies. Design aspects, characteristics, actual flight testing statistics, principles of the Iridium modems and communication paths are described including payload and support instrumentation interfacing. Not limited to high altitude ballooning, the Iridium communications platform opens a new era in remote commanding and data retrieval.

  16. Image Positioning Accuracy Analysis for the Super Low Altitude Remote Sensing Satellite

    Directory of Open Access Journals (Sweden)

    Ming Xu

    2012-10-01

    Full Text Available Super low altitude remote sensing satellites maintain lower flight altitudes by means of ion propulsion in order to improve image resolution and positioning accuracy. The use of engineering data in design for achieving image positioning accuracy is discussed in this paper based on the principles of the photogrammetry theory. The exact line‐of‐sight rebuilding of each detection element and this direction precisely intersecting with the Earth’s elliptical when the camera on the satellite is imaging are both ensured by the combined design of key parameters. These parameters include: orbit determination accuracy, attitude determination accuracy, camera exposure time, accurately synchronizing the reception of ephemeris with attitude data, geometric calibration and precise orbit verification. Precise simulation calculations show that image positioning accuracy of super low altitude remote sensing satellites is not obviously improved. The attitude determination error of a satellite still restricts its positioning accuracy.

  17. Computational mission analysis and conceptual system design for super low altitude satellite

    Institute of Scientific and Technical Information of China (English)

    Ming Xu; Jinlong Wang; Nan Zhou

    2014-01-01

    This paper deals with system engineering and design methodology for super low altitude satel ites in the view of the com-putational mission analysis. Due to the slight advance of imaging instruments, such as the focus of camera and the image element of charge coupled device (CCD), it is an innovative and economical way to improve the camera’s resolution to enforce the satel ite to fly on the lower altitude orbit. DFH-3, the mature satel ite bus de-veloped by Chinese Academy of Space Technology, is employed to define the mass and power budgets for the computational mis-sion analysis and the detailed engineering design for super low altitude satel ites. An effective iterative algorithm is proposed to solve the ergodic representation of feasible mass and power bud-gets at the flight altitude under constraints. Besides, boundaries of mass or power exist for every altitude, where the upper boundary is derived from the maximum power, while the minimum thrust force holds the lower boundary before the power reaching the initial value. What’s more, an analytical algorithm is employed to numerical y investigate the coverage percentage over the altitude, so that the nominal altitude could be selected from al the feasi-ble altitudes based on both the mass and power budgets and the repetitive ground traces. The local time at the descending node is chosen for the nominal sun-synchronous orbit based on the average evaluation function. After determining the key orbital ele-ments based on the computational mission analysis, the detailed engineering design on the configuration and other subsystems, like power, telemetry telecontrol and communication (TT&C), and attitude determination and control system (ADCS), is performed based on the benchmark bus, besides, some improvements to the bus are also implemented to accommodate the flight at a super low altitude. Two operation strategies, drag-free closed-loop mode and on/off open-loop mode, are presented to maintain the satel

  18. A concept of the energy storable orbital power station (ESOPS)

    Science.gov (United States)

    Akiba, Ryojiro; Takano, Tadashi; Yokota, Hiroki

    To save foreseeable difficulties and risks associated with large scale development of the Space Power Station on GEO at a remote distance, the Energy Storable Orbital Power Station (ESOPS) placed in a near earth orbit is proposed. Most promising orbit for ESOPS is a fixed periapsis pseudo sun synchronous orbit. A thermodynamical power generation is preferable owing to its inherent insensitive nature against radiation suffered on the medium altitude orbit. Thermal energy storage using latent heat of fusion seems the best choice for this system. The power transmission from ESOPS to ground station presents most critical problems due to non-stationary characteristics.

  19. Orbital angular momentum microlaser

    Science.gov (United States)

    Miao, Pei; Zhang, Zhifeng; Sun, Jingbo; Walasik, Wiktor; Longhi, Stefano; Litchinitser, Natalia M.; Feng, Liang

    2016-07-01

    Structured light provides an additional degree of freedom for modern optics and practical applications. The effective generation of orbital angular momentum (OAM) lasing, especially at a micro- and nanoscale, could address the growing demand for information capacity. By exploiting the emerging non-Hermitian photonics design at an exceptional point, we demonstrate a microring laser producing a single-mode OAM vortex lasing with the ability to precisely define the topological charge of the OAM mode. The polarization associated with OAM lasing can be further manipulated on demand, creating a radially polarized vortex emission. Our OAM microlaser could find applications in the next generation of integrated optoelectronic devices for optical communications in both quantum and classical regimes.

  20. Orbital angular momentum microlaser.

    Science.gov (United States)

    Miao, Pei; Zhang, Zhifeng; Sun, Jingbo; Walasik, Wiktor; Longhi, Stefano; Litchinitser, Natalia M; Feng, Liang

    2016-07-29

    Structured light provides an additional degree of freedom for modern optics and practical applications. The effective generation of orbital angular momentum (OAM) lasing, especially at a micro- and nanoscale, could address the growing demand for information capacity. By exploiting the emerging non-Hermitian photonics design at an exceptional point, we demonstrate a microring laser producing a single-mode OAM vortex lasing with the ability to precisely define the topological charge of the OAM mode. The polarization associated with OAM lasing can be further manipulated on demand, creating a radially polarized vortex emission. Our OAM microlaser could find applications in the next generation of integrated optoelectronic devices for optical communications in both quantum and classical regimes. PMID:27471299

  1. Polarization versus photon spin

    OpenAIRE

    Luis Aina, Alfredo; Rodil, Alfonso

    2014-01-01

    We examine whether the Stokes parameters of a two-mode electromagnetic field results from the superposition of the spins of the photons it contains. To this end we express any n-photon state as the result of the action on the vacuum of n creation operators generating photons which can have may different polarization states in general. We find that the macroscopic polarization holds as sum of the single-photon Stokes parameters only for the SU(2) orbits of photon-number states. The states that...

  2. A Mars' Year of Topographic Mapping With The Mars Orbiter Laser Altimeter

    Science.gov (United States)

    Smith, David E.; Zuber, Maria T.

    2001-01-01

    Since the end of February 1999 the Mars Orbiter Laser Altimeter (MOLA) has been mapping the planet continuously except for a 2 month period around solar conjunction in June 2000. At the end of January 2001 the Mars Global Surveyor Spacecraft (MGS) had completed its prime Mission, one Mars year of observing the planet, and begun the Extended Mission of slightly more than 14 months. MOLA will had acquired over 530 million altimetric measurements by early 2001, and continued to work perfectly. During the Extended Mission the main objective for MOLA will be observations of the seasonal variations in the locations and altitudes of clouds, the changes in the elevations of the polar icecaps due to the deposition and sublimation Of CO2, as well as supporting NASA's search for suitable future landing sites.

  3. Rocket Engine Altitude Simulation Technologies

    Science.gov (United States)

    Woods, Jody L.; Lansaw, John

    2010-01-01

    John C. Stennis Space Center is embarking on a very ambitious era in its rocket engine propulsion test history. The first new large rocket engine test stand to be built at Stennis Space Center in over 40 years is under construction. The new A3 Test Stand is designed to test very large (294,000 Ibf thrust) cryogenic propellant rocket engines at a simulated altitude of 100,000 feet. A3 Test Stand will have an engine testing chamber where the engine will be fired after the air in the chamber has been evacuated to a pressure at the simulated altitude of less than 0.16 PSIA. This will result in a very unique environment with extremely low pressures inside a very large chamber and ambient pressures outside this chamber. The test chamber is evacuated of air using a 2-stage diffuser / ejector system powered by 5000 lb/sec of steam produced by 27 chemical steam generators. This large amount of power and flow during an engine test will result in a significant acoustic and vibrational environment in and around A3 Test Stand.

  4. Stochastic Analysis of Orbital Lifetimes of Spacecraft

    Science.gov (United States)

    Sasamoto, Washito; Goodliff, Kandyce; Cornelius, David

    2008-01-01

    A document discusses (1) a Monte-Carlo-based methodology for probabilistic prediction and analysis of orbital lifetimes of spacecraft and (2) Orbital Lifetime Monte Carlo (OLMC)--a Fortran computer program, consisting of a previously developed long-term orbit-propagator integrated with a Monte Carlo engine. OLMC enables modeling of variances of key physical parameters that affect orbital lifetimes through the use of probability distributions. These parameters include altitude, speed, and flight-path angle at insertion into orbit; solar flux; and launch delays. The products of OLMC are predicted lifetimes (durations above specified minimum altitudes) for the number of user-specified cases. Histograms generated from such predictions can be used to determine the probabilities that spacecraft will satisfy lifetime requirements. The document discusses uncertainties that affect modeling of orbital lifetimes. Issues of repeatability, smoothness of distributions, and code run time are considered for the purpose of establishing values of code-specific parameters and number of Monte Carlo runs. Results from test cases are interpreted as demonstrating that solar-flux predictions are primary sources of variations in predicted lifetimes. Therefore, it is concluded, multiple sets of predictions should be utilized to fully characterize the lifetime range of a spacecraft.

  5. A novel technique to construct the global distribution of whistler mode chorus wave intensity using low-altitude POES electron data

    Science.gov (United States)

    Ni, Binbin; Li, Wen; Thorne, Richard M.; Bortnik, Jacob; Green, Janet C.; Kletzing, Craig A.; Kurth, William S.; Hospodarsky, George B.; Soria-Santacruz Pich, Maria

    2014-07-01

    Although magnetospheric chorus plays a significant role in the acceleration and loss of radiation belt electrons, its global evolution during any specific time period cannot be directly obtained by spacecraft measurements. Using the low-altitude NOAA Polar-orbiting Operational Environmental Satellite (POES) electron data, we develop a novel physics-based methodology to infer the chorus wave intensity and construct its global distribution with a time resolution of less than an hour. We describe in detail how to apply the technique to satellite data by performing two representative analyses, i.e., (i) for one specific time point to visualize the estimation procedure and (ii) for a particular time period to validate the method and construct an illustrative global chorus wave model. We demonstrate that the spatiotemporal evolution of chorus intensity in the equatorial magnetosphere can be reasonably estimated from electron flux measurements made by multiple low-altitude POES satellites with a broad coverage of L shell and magnetic local time. Such a data-based, dynamic model of chorus waves can provide near-real-time wave information on a global scale for any time period where POES electron data are available. A combination of the chorus wave spatiotemporal distribution acquired using this methodology and the direct spaceborne wave measurements can be used to evaluate the quantitative scattering caused by resonant wave-particle interactions and thus model radiation belt electron variability.

  6. Rings of earth. [orbiting bands of space debris

    Science.gov (United States)

    Goldstein, Richard M.; Randolph, L. W.

    1992-01-01

    Small particles moving at an orbital velocity of 7.6 kilometers per second can present a considerable hazard to human activity in space. For astronauts outside of the protective shielding of their space vehicles, such particles can be lethal. The powerful radar at NASA's Goldstone Deep Communications Complex was used to monitor such orbital debris. This radar can detect metallic objects as small as 1.8 mm in diameter at 600 km altitude. The results of the preliminary survey show a flux (at 600 km altitude) of 6.4 objects per square kilometer per day of equivalent size of 1.8 mm or larger. Forty percent of the observed particles appear to be concentrated into two orbits. An orbital ring with the same inclination as the radar (35.1 degrees) is suggested. However, an orbital band with a much higher inclination (66 degrees) is also a possibility.

  7. High-altitude cerebral oedema mimicking stroke

    OpenAIRE

    Yanamandra, Uday; Gupta, Amul; Patyal, Sagarika; Varma, Prem Prakash

    2014-01-01

    High-altitude cerebral oedema (HACO) is the most fatal high-altitude illness seen by rural physicians practising in high-altitude areas. HACO presents clinically with cerebellar ataxia, features of raised intracranial pressure (ICP) and coma. Early identification is important as delay in diagnosis can be fatal. We present two cases of HACO presenting with focal deficits mimicking stroke. The first patient presented with left-sided hemiplegia associated with the rapid deterioration in the sens...

  8. Atmospheric Drag Perturbation in an Autonomous Orbit Determination for Satellite

    Institute of Scientific and Technical Information of China (English)

    XUE shen-fang; JIN Sheng-zhen; NING Shu-nian; SUN Cai-hong

    2005-01-01

    In this paper, an autonomous orbit determination method for satellite using a large field of view star sensor is presented. The simulation of orbit under atmospheric drag perturbation are given with expanded Kalman filtering.The large field of view star sensor has the same precision as star sensor and a sufficient filed of view. Therefore ,the refraction stars can be observed more accurately in real time. The geometric relation between the refracted starlight and the earth can be determined by tangent altitude of the refraction starlight. And then the earth enter can be determined in satellite body frame. The simulation shows that the precision of the mean square deviation of satellite's position and velocity is 5m and 0.01m/s respectively. The calculated decrement of the semi-major axis in one day is close to the theoretical result, and the absolute error is in the range of decimeter when the altitude of orbit is 750 km. The simulateion of orbit of different initial semi-major axis shows that the higher the altitude of orbit is, the smaller the decrement of the semi-major axis is, and when the altitude of orbit is 1700 km the decimeter of the semi-major axis is 10-7km.

  9. GEODYN Orbit Determination of Dawn at Vesta using Image Constraints

    Science.gov (United States)

    Centinello, F. J., III; Mazarico, E.; Zuber, M. T.

    2012-12-01

    The Dawn spacecraft has completed the orbital phase of its mapping mission of the asteroid 4 Vesta. We utilized radiometric measurements and image constraints to compute the spacecraft orbit using the GEODYN II orbit determination software. Image constraints are computed control point vectors which point from the spacecraft to landmarks observed in two images of the same region of Vesta, and are a newly developed measurement type for GEODYN. This capability was added because image constraints can provide supplemental information on the spacecraft trajectory especially in a weak gravity environment. Due to the geometric nature of image constraints, they can reduce the orbital errors in the along- and cross-track directions, which have typically carried higher uncertainty in previous interplanetary missions. Image constraints are also useful during times of absence of radiometric tracking data. Improvements to orbit determination can provide improved gravity field estimation and knowledge of the interior structure of Vesta. The NASA Deep Space Network (DSN) provides X-band tracking measurements for Dawn. Radiometric and image constraints were processed for the High Altitude Mapping Orbit (HAMO) I and II, and the Low Altitude Mapping Orbit (LAMO), from 23 Sept 2011 to 26 July 2012. The spacecraft altitude was roughly 685 km during HAMO and 200 km during LAMO. Doppler and range residual RMS were under 1 mm/s and 10 m, respectively. Improvement in orbital knowledge from image constraints is typically greatest in the cross-track direction and in our analysis these residuals were typically better than 500 m.

  10. Aspirated Compressors for High Altitude Engines Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Aurora Flight Sciences proposes to incorporate aspirated compressor technology into a high altitude, long endurance (HALE) concept engine. Aspiration has been...

  11. Fire Fighting from High Altitude

    Science.gov (United States)

    Cobleigh, Brent; Ambrosia, Vince

    2007-01-01

    A viewgraph presentation on high altitude fire fighting is shown. The topics include: 1) Yellowstone Fire - 1988; 2) 2006 Western States Fire Mission Over-View; 3) AMS-Wildfire Scanner; 4) October 24-25 Mission: Yosemite NP and NF; 5) October 24-25 Mission MODIS Overpass; 6) October 24-25 Mission Highlights; 7) October 28-29 Mission Esperanza Fire, California; 8) Response to the Esperanza Fire in Southern California -- Timeline Oct 27-29 2006; 9) October 28-29 Mission Esperanza Fire Altair Flight Routing; 10) October 28-29 Mission Esperanza Fire Altair Over-Flights; 11) October 28-29 Mission Highlights; 12) Results from the Esperanza Fire Response; 13) 2007 Western States Fire Mission; and 14) Western States UAS Fire Mission 2007

  12. Orbital rotation without orbital angular momentum: mechanical action of the spin part of the internal energy flow in light beams

    DEFF Research Database (Denmark)

    Angelsky, O. V.; Bekshaev, A. Ya; Maksimyak, P. P.;

    2012-01-01

    The internal energy flow in a light beam can be divided into the "orbital" and "spin" parts, associated with the spatial and polarization degrees of freedom of light. In contrast to the orbital one, experimental observation of the spin flow seems problematic because it is converted into an orbital...

  13. Certification and safety aspects relating to the transport of passengers on high altitude balloons in Europe

    Science.gov (United States)

    Schoenmaker, Annelie

    2014-07-01

    High-altitude balloons typically fly between 25 and 50 km in altitude, which, while below the Karman line of 100 km, is yet far above the altitudes typically flown by aircraft. For example, the highest-flying commercial aircraft - the Concorde - had a maximum cruising altitude of only 18 km. zero2infinity, a Spanish company, is currently developing a pressurized pod named “bloon” which will be capable of lifting six people, including two pilot crew members and four paying passengers, to an altitude of 36 km through the use of high-altitude balloons. The boundary between Airspace and Outer Space has never been legally defined, mostly because of the lack of activities taking place between the altitude where airplanes fly and the lowest orbiting spacecraft. High-altitude balloons do fly at these in-between altitudes and the prospect of commercializing access to these parts of the stratosphere poses some questions in a new light. Given the relatively low altitude at which they fly, it may well be that these types of balloons would be considered to operate exclusively within air space. However, given the technology involved in crewed high altitude balloon flights, which is more similar to spacecraft engineering than to traditional hot-air or gas ballooning, it is necessary to evaluate the various legal regimes, codes, and regulations that would apply to such flights, especially regarding licenses and liabilities. For high altitude balloon flights commencing in Europe, the European Aviation Safety Agency (EASA) would very likely be the competent certification or licensing agency for these flights, although there would likely be input from various national aviation authorities as well. However, because the European Commission (EC) has not yet issued regulations regarding commercial spaceflight, particularly the use of high altitude balloons, new rules and regulations governing such flights may still need to be drafted and promulgated. With the development of

  14. Geometric orbit datum and orbit covers

    Institute of Scientific and Technical Information of China (English)

    梁科; 侯自新

    2001-01-01

    Vogan conjectured that the parabolic induction of orbit data is independent of the choice of the parabolic subgroup. In this paper we first give the parabolic induction of orbit covers, whose relationship with geometric orbit datum is also induced. Hence we show a geometric interpretation of orbit data and finally prove the conjugation for geometric orbit datum using geometric method.

  15. Auroral and magnetic variations in the polar cusp and cleft. Signatures of magnetopause boundary layer dynamics

    International Nuclear Information System (INIS)

    By combining continous ground-based observations of polar cleft/cusp auroras and local magnetic variations with electromagnetic parameters obtained from satellites in polar orbit (low-altitude cleft/cusp) and in the magnetosheath/interplanetary space, different electrodynamic processes in the polar cleft/cusp have been investigated. One of the more controversial questions in this field is related to the observed shifts in latitude of cleft/cusp auroras and the relationships with the interplanetary magnetic field (IMF) orientation, local magnetic disturbances (DP2 and DPY modes) and magnetospheric substorms. A new approach which may contribute to clarifying these complicated relationships, simultaneous groundbased observations of the midday and evening-midnight sectors of the auroral oval, is illustrated. A related topic is the spatial relationship between the cleft/cusp auroras and the ionospheric convection currents. A characteristic feature of the polar cusp and cleft regions during negative IMF Bz is repeated occurrence of certain short-lived auroral structures moving in accordance with the local convection pattern. Satellite measurements of particle precipitation, magnetic field and ion drift components permit detailed investigations of the electrodynamics of these cusp/cleft structures. Information on electric field components, Birkeland currents, Poynting flux, height-integrated Pedersen conductivity and Joule heat dissipation rate has been derived. These observations are discussed in relation to existing models of temporal plasma injections from the magnetosheath

  16. Physiological aspects of altitude training and the use of altitude simulators

    OpenAIRE

    Ranković Goran; Radovanović Dragan

    2005-01-01

    Altitude training in various forms is widely practiced by athletes and coaches in an attempt to improve sea level endurance. Training at high altitude may improve performance at sea level through altitude acclimatization, which improves oxygen transport and/or utilization, or through hypoxia, which intensifies the training stimulus. This basic physiological aspect allows three training modalities: live high and train high (classic high-altitude training), live low and train high (training thr...

  17. Altitude as handicap in rank-order football tournaments

    OpenAIRE

    Fawaz, Yarine; Casas, Agustin

    2013-01-01

    In 2007, based on medical reports, FIFA ruled that no international football competition could be played in stadiums with an altitude higher than 2500 meters. We provide stark evidence which supports the claim that playing in high altitude benefits the home team through two channels. First, in these scenarios, high altitude teams (HAT) do better against low altitude teams than against other high altitude teams. Second, every time that low altitude teams visit other high altitude teams they ge...

  18. Eye and orbit ultrasound

    Science.gov (United States)

    Echography - eye orbit; Ultrasound - eye orbit; Ocular ultrasonography; Orbital ultrasonography ... ophthalmology department of a hospital or clinic. Your eye is numbed with medicine (anesthetic drops). The ultrasound ...

  19. Objects orbiting the Earth in deep resonance

    CERN Document Server

    Sampaio, J C; de Moraes, R Vilhena; Fernandes, S S

    2012-01-01

    The increasing number of objects orbiting the Earth justifies the great attention and interest in the observation, spacecraft protection and collision avoidance. These studies involve different disturbances and resonances in the orbital motions of these objects distributed by the distinct altitudes. In this work, the TLE (Two-Line Elements) of the NORAD are studied observing the resonant period of the objects orbiting the Earth and the main resonance in the LEO region. The time behavior of the semi-major axis, eccentricity and inclination of some space debris are studied. Possible irregular motions are observed by the frequency analysis and by the presence of different resonant angles describing the orbital dynamics of these objects.

  20. Delayed appearance of high altitude retinal hemorrhages.

    Directory of Open Access Journals (Sweden)

    Daniel Barthelmes

    Full Text Available BACKGROUND: Retinal hemorrhages have been described as a component of high altitude retinopathy (HAR in association with altitude illness. In this prospective high altitude study, we aimed to gain new insights into the pathophysiology of HAR and explored whether HAR could be a valid early indicator of altitude illness. METHODOLOGY/PRINCIPAL FINDINGS: 28 mountaineers were randomly assigned to two ascent profiles during a research expedition to Mt. Muztagh Ata (7546 m/24,751 ft. Digital fundus photographs were taken prior to expedition at 490 m (1,607 ft, during expedition at 4497 m (14,750 ft = base camp, 5533 m (18,148 ft, 6265 m (20,549 ft, 6865 m (22,517 ft and 4.5 months thereafter at 490 m. Number, size and time of occurrence of hemorrhages were recorded. Oxygen saturation (SpO₂ and hematocrit were also assessed. 79% of all climbers exhibited retinal hemorrhages during the expedition. Number and area of retinal bleeding increased moderately to medium altitudes (6265 m. Most retinal hemorrhages were detected after return to base camp from a high altitude. No post-expeditional ophthalmic sequelae were detected. Significant negative (SpO₂ Beta: -0.4, p<0.001 and positive (hematocrit Beta: 0.2, p = 0.002, time at altitude Beta: 0.33, p = 0.003 correlations with hemorrhages were found. CONCLUSIONS/SIGNIFICANCE: When closely examined, a very large amount of climbers exhibit retinal hemorrhages during exposure to high altitudes. The incidence of retinal hemorrhages may be greater than previously appreciated as a definite time lag was observed between highest altitude reached and development of retinal bleeding. Retinal hemorrhages should not be considered warning signs of impending severe altitude illness due to their delayed appearance.

  1. Prospective Ukrainian lunar orbiter mission

    Science.gov (United States)

    Shkuratov, Y.; Litvinenko, L.; Shulga, V.; Yatskiv, Y.; Kislyuk, V.

    Ukraine has launch vehicles that are able to deliver about 300 kg to the lunar orbit. Future Ukrainian lunar program may propose a polar orbiter. This orbiter should fill principal information gaps in our knowledge about the Moon after Clementine and Lunar Prospector missions and the future missions, like Smart-1, Lunar-A, and Selene. We consider that this can be provided by radar studies of the Moon with supporting optical polarimetric observations from lunar polar orbit. These experiments allow one to better understand global structure of the lunar surface in a wide range of scales, from microns to kilometers. We propose three instruments for the prospective lunar orbiter. They are: a synthetic aperture imaging radar (SAR), ground-penetrating radar (GPR), and imaging polarimeter (IP). The main purpose of SAR is to study with high resolution (50 m) the permanently shadowed sites in the lunar polar regions. These sites are cold traps for volatiles, and have a potential of resource utilization. Possible presence of water ice in the regolith in the sites makes them interesting for permanent manned bases on the Moon. Radar imaging and mapping of other interesting regions could be also planned. Multi-frequencies multi-polarization soun d ing of the lunar surface with GPR can provide information about internal structure of the lunar surface from meters to several hundred meters deep. GPR can be used for measuring the megaregolith layer properties, detection of cryptomaria, and studies of internal structure of the largest craters. IP will be a CCD camera with an additional suite of polarizers. Modest spatial resolution (100 m) should provide a total coverage or a large portion of the lunar surface in oblique viewing basically at large phase angles. Polarization degree at large (>90°) phase angles bears information about characteristic size of the regolith particles. Additional radiophysical experiments are considered with the use of the SAR system, e.g., bistatic radar

  2. Proton isotropy boundaries as measured on mid- and low-altitude satellites

    Directory of Open Access Journals (Sweden)

    N. Yu. Ganushkina

    2005-07-01

    Full Text Available Polar CAMMICE MICS proton pitch angle distributions with energies of 31-80 keV were analyzed to determine the locations where anisotropic pitch angle distributions (perpendicular flux dominating change to isotropic distributions. We compared the positions of these mid-altitude isotropic distribution boundaries (IDB for different activity conditions with low-altitude isotropic boundaries (IB observed by NOAA 12. Although the obtained statistical properties of IDBs were quite similar to those of IBs, a small difference in latitudes, most pronounced on the nightside and dayside, was found. We selected several events during which simultaneous observations in the same local time sector were available from Polar at mid-altitudes, and NOAA or DMSP at low-altitudes. Magnetic field mapping using the Tsyganenko T01 model with the observed solar wind input parameters showed that the low- and mid-altitude isotropization boundaries were closely located, which leads us to suggest that the Polar IDB and low-altitude IBs are related. Furthermore, we introduced a procedure to control the difference between the observed and model magnetic field to reduce the large scatter in the mapping. We showed that the isotropic distribution boundary (IDB lies in the region where Rc/ρ~6, that is at the boundary of the region where the non-adiabatic pitch angle scattering is strong enough. We therefore conclude that the scattering in the large field line curvature regions in the nightside current sheet is the main mechanism producing isotropization for the main portion of proton population in the tail current sheet. This mechanism controls the observed positions of both IB and IDB boundaries. Thus, this tail region can be probed, in its turn, with observations of these isotropy boundaries.

    Keywords. Magnetospheric physics (Energetic particles, Precipitating; Magnetospheric configuration and dynamics; Magnetotail

  3. Precision orbit determination software validation experiment

    Science.gov (United States)

    Schutz, B. E.; Tapley, B. D.; Eanes, R. J.; Marsh, J. G.; Williamson, R. G.; Martin, T. V.

    1980-01-01

    This paper presents the results of an experiment which was designed to ascertain the level of agreement between GEODYN and UTOPIA, two completely independent computer programs used for precision orbit determination, and to identify the sources which limit the agreement. For a limited set of models and a seven-day data set arc length, the altitude components of the ephemeris obtained by the two programs agree at the sub-centimeter level throughout the arc.

  4. Inflammation of the Orbit

    Science.gov (United States)

    ... Diagnosis Treatment Medical Dictionary Additional Content Medical News Inflammation of the Orbit (Inflammatory Orbital Pseudotumor) By James ... Introduction to Eye Socket Disorders Cavernous Sinus Thrombosis Inflammation of the Orbit Orbital Cellulitis Preseptal Cellulitis Tumors ...

  5. Intercomparison of polar ozone profiles by IASI/MetOp sounder with 2010 Concordiasi ozonesonde observations

    Directory of Open Access Journals (Sweden)

    J. Gazeaux

    2012-10-01

    Full Text Available Validation of ozone profiles measured from a nadir looking satellite instrument over Antarctica is a challenging task due to differences in their height sensitivity with ozonesonde measurements. In this paper we compare the ozone observations provided by the Infrared Atmospheric Sounding Interferometer (IASI instrument onboard the polar-orbiting satellite MetOp with ozone profiles collected between August and October 2010 at McMurdo Station, Antarctica, during the Concordiasi campaign. This campaign was aimed at satellite data validation and up to 20 zero-pressure sounding balloons carrying ozonesondes were launched during this period when the MetOp satellite was passing above McMurdo. This makes the dataset relevant for comparison, especially because those balloons covered the entire altitude range of IASI profiles. The validation methodology and the collocation criteria differ according to the availability of Global Positioning System auxiliary data with each Electro-Chemical Cell ozonesonde observation. We show that the relative mean difference depends on the altitude range investigated. The analysis shows a good agreement in the troposphere (below 10 km and middle stratosphere (25–40 km, where the differences are lower than 10%. However a significant positive bias of about 10–26% is estimated in the lower stratosphere at 10–25 km, depending on altitude. The positive bias in the 10–25 km range is consistent with previously reported studies comparing in-situ data with thermal infrared satellite measurements. This study allows a better characterization of the IASI products over the polar region when ozone depletion/recovery is occurring.

  6. Orbit Design and Simulation for Kufasat Nanosatellite

    Science.gov (United States)

    Mahdi, Mohammed Chessab

    2015-12-01

    Orbit design for KufaSat Nano-satellites is presented. Polar orbit is selected for the KufaSat mission. The orbit was designed with an Inclination which enables the satellite to see every part of the earth. KufaSat has a payload for imaging purposes which require a large amount of power, so the orbit is determined to be sun synchronous in order to provide the power through solar panels. The KufaSat mission is designed for the low earth orbit. The six initial Keplerian Elements of KufaSat are calculated. The orbit design of KufaSat according to the calculated Keplerian elements has been simulated and analyzed by using MATLAB first and then by using General Mission Analysis Tool.

  7. Orbit analysis

    International Nuclear Information System (INIS)

    The past fifteen years have witnessed a remarkable development of methods for analyzing single particle orbit dynamics in accelerators. Unlike their more classic counterparts, which act upon differential equations, these methods proceed by manipulating Poincare maps directly. This attribute makes them well matched for studying accelerators whose physics is most naturally modelled in terms of maps, an observation that has been championed most vigorously by Forest. In the following sections the author sketchs a little background, explains some of the physics underlying these techniques, and discusses the best computing strategy for implementing them in conjunction with modeling accelerators

  8. Orbit analysis

    Energy Technology Data Exchange (ETDEWEB)

    Michelotti, L.

    1995-01-01

    The past fifteen years have witnessed a remarkable development of methods for analyzing single particle orbit dynamics in accelerators. Unlike their more classic counterparts, which act upon differential equations, these methods proceed by manipulating Poincare maps directly. This attribute makes them well matched for studying accelerators whose physics is most naturally modelled in terms of maps, an observation that has been championed most vigorously by Forest. In the following sections the author sketchs a little background, explains some of the physics underlying these techniques, and discusses the best computing strategy for implementing them in conjunction with modeling accelerators.

  9. Brane orbits

    Energy Technology Data Exchange (ETDEWEB)

    Bergshoeff, Eric A., E-mail: E.A.Bergshoeff@rug.nl [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Marrani, Alessio, E-mail: Alessio.Marrani@cern.ch [Physics Department, Theory Unit, CERN, CH-1211, Geneva 23 (Switzerland); Riccioni, Fabio, E-mail: Fabio.Riccioni@roma1.infn.it [INFN Sezione di Roma, Dipartimento di Fisica, Universita di Roma ' La Sapienza' , Piazzale Aldo Moro 2, 00185 Roma (Italy)

    2012-08-01

    We complete the classification of half-supersymmetric branes in toroidally compactified IIA/IIB string theory in terms of representations of the T-duality group. As a by-product we derive a last wrapping rule for the space-filling branes. We find examples of T-duality representations of branes in lower dimensions, suggested by supergravity, of which none of the component branes follow from the reduction of any brane in ten-dimensional IIA/IIB string theory. We discuss the constraints on the charges of half-supersymmetric branes, determining the corresponding T-duality and U-duality orbits.

  10. Haematological Studies in High Altitude Natives at Plains and on Return to High Altitude

    Directory of Open Access Journals (Sweden)

    S. C. Jain

    1988-04-01

    Full Text Available Haematologic studies were carried out in 20 high altitude natives during two months stay at plains (200 m and on their return to an altitude of 3,500 m. Haemoglobin, erythrocyte count, haematocrit and reticulocyte count decreased rapidly on arrival to plains and attained minimum level by the end of fourth week. All these parameters increased rapidly on return to high altitude and were found to attain maximum values by 23rd day on return to high altitude. Mean cell volume and mean cell haemoglobin showed significant increase at altitude. Blood volume and red cell mass increased significantly at altitude. It is concluded that the high altitude natives of Ladakh were well adapted to hypoxic environment due to normocythaemic hypervolemia.

  11. Analysis of fine ELF wave structures observed poleward from the ionospheric trough by the low-altitude satellite DEMETER

    Science.gov (United States)

    Parrot, Michel; Nęmec, František; Santolík, Ondřej

    2014-03-01

    DEMETER was a three-axis stabilized Earth-pointing spacecraft launched on 29 June 2004 into a low-altitude (710 km) polar and circular orbit that was subsequently lowered to 650 km until the end of the mission in December 2010. DEMETER measured electromagnetic waves all around the Earth except at magnetic invariant latitudes >65°. The frequency range for the electric field was from DC up to 3.5 MHz and for the magnetic field from a few hertz up to 20 kHz. Electromagnetic ion cyclotron (EMIC) waves have been previously observed by DEMETER close to the ionospheric trough during high magnetic activity, and this paper describes another type of EMIC waves. These waves are also observed close to the trough, but they extend poleward, with the trough acting as a boundary. They are observed exclusively during the night and preferentially during geomagnetic substorms. The analysis of wave propagation shows that they propagate nearly along the ambient magnetic field and that they come from larger radial distances.

  12. Low-Altitude Magnetic Topology with MAVEN SWEA and MAG

    Science.gov (United States)

    Mitchell, David; Xu, Shaosui; Mazelle, Christian; Luhmann, Janet; McFadden, James; Connerney, John; Liemohn, Michael; Dong, Chuanfei; Bougher, Stephen; Fillingim, Matthew

    2016-04-01

    The Solar Wind Electron Analyzer (SWEA) and Magnetometer (MAG) onboard the MAVEN spacecraft measure electron pitch angle and energy distributions at 2-second resolution (~8 km along the orbit track) to determine the topology of magnetic fields from both external and crustal sources. Electrons from different regions of the Mars environment can be distinguished by their energy distributions. Thus, pitch angle resolved energy spectra can be used to determine the plasma source regions sampled by a field line at large distances from the spacecraft. From 12/1/2014 to 2/15/2015, when periapsis was at high northern latitudes, SWEA observed ionospheric photoelectrons at low altitudes (140-200 km) and high solar zenith angles (120-145 degrees) on ~35% of the orbits. Since this electron population is unambiguously produced in the dayside ionosphere, these observations demonstrate that the deep Martian nightside is at times magnetically connected to the sunlit hemisphere. The BATS-R-US Mars multi-fluid MHD model suggests the presence of closed crustal magnetic field lines over the northern hemisphere that straddle the terminator and extend to high SZA. Simulations with the SuperThermal Electron Transport (STET) model show that photoelectron transport along such field lines can take place without significant attenuation. Precipitation of photoelectrons onto the night-side atmosphere should cause ionization and possibly auroral emissions in localized regions. On one orbit, the O2+ energy flux measured by STATIC correlates well with precipitating photoelectron fluxes.

  13. [Sildenafil and exercise performance at altitude].

    Science.gov (United States)

    Peidro, Roberto M

    2015-01-01

    Barometric pressure and partial oxygen pressure decrease with increasing altitude. Hypobaric hypoxia produced is responsible for altitude-related diseases and it can cause severe decrements in exercise performance. The physiological adaptations to the altitude are multiple and they contribute to alter different athletic qualities. The VO2 worsening could be associated to increased pulmonary vascular resistance and nitric oxide diffusion alteration. Performance impairments at altitude can also be accentuated by hypoxia-induced elevations in pulmonary arterial pressure. Clinical studies have demonstrated the beneficial effects of sildenafil on the treatment of pulmonary hypertension. These effects have led to suggest that its indication for competitions at altitude might improve athletic performance. The investigations demonstrate different results depending on the altitude level and times and intensities of exercise. Some studies show performance improvements, although not in all participants. Individual responses vary widely between different athletes. This presentation examines the effects of altitude on exercise capacity and shows studies about the use of sildenafil to improve sport performance. This text also discusses the possible side effects and implications for the use of sildenafil in athletes, indication that is not the basic one of the drug. The physicians must know in each athlete the individual sildenafil side effects that could arise and that would influence negatively on health and performance. PMID:26339884

  14. Ion Polarization Scheme for MEIC

    CERN Document Server

    Kondratenko, A M; Filatov, Yu N; Derbenev, Ya S; Lin, F; Morozov, V S; Zhang, Y

    2016-01-01

    The choice of a figure 8 shape for the booster and collider rings of MEIC opens wide possibilities for preservation of the ion polarization during beam acceleration as well as for control of the polarization at the collider's interaction points. As in the case of accelerators with Siberian snakes, the spin tune is energy independent but is equal to zero instead of one half. The figure-8 topology eliminates the effect of arcs on the spin motion. There appears a unique opportunity to control the polarization of any particle species including deuterons, using longitudinal fields of small integrated strength (weak solenoids). Contrary to existing schemes, using weak solenoids in figure-8 colliders, one can control the polarization at the interaction points without essentially any effect on the beam's orbital characteristics. A universal scheme for control of the polarization using weak solenoids provides an elegant solution to the problem of ion acceleration completely eliminating resonant beam depolarization. It...

  15. Hyperon polarization in the constituent quark model

    International Nuclear Information System (INIS)

    A mechanism for hyperon polarization in the inclusive production is considered. The main role belongs to the orbital angular momentum and polarization of strange quark-antiquark pairs in the internal structure of constituent quarks. The nonperturbative hadron structure is based on the results of chiral quark models

  16. High-Altitude Hydration System

    Science.gov (United States)

    Parazynski, Scott E.; Orndoff, Evelyne; Bue, Grant C.; Schaefbauer, Mark E.; Urban, Kase

    2010-01-01

    Three methods are being developed for keeping water from freezing during high-altitude climbs so that mountaineers can remain hydrated. Three strategies have been developed. At the time of this reporting two needed to be tested in the field and one was conceptual. The first method is Passive Thermal Control Using Aerogels. This involves mounting the fluid reservoir of the climber s canteen to an inner layer of clothing for better heat retention. For the field test, bottles were mounted to the inner fleece layer of clothing, and then aerogel insulation was placed on the outside of the bottle, and circumferentially around the drink straw. When climbers need to drink, they can pull up the insulated straw from underneath the down suit, take a sip, and then put it back into the relative warmth of the suit. For the field test, a data logger assessed the temperatures of the water reservoir, as well as near the tip of the drink straw. The second method is Passive Thermal Control with Copper-Shielded Drink Straw and Aerogels, also mounted to inner layers of clothing for better heat retention. Braided wire emanates from the inside of the fleece jacket layer, and continues up and around the drink straw in order to use body heat to keep the system-critical drink straw warm enough to keep water in the liquid state. For the field test, a data logger will be used to compare this with the above concept. The third, and still conceptual, method is Active Thermal Control with Microcontroller. If the above methods do not work, microcontrollers and tape heaters have been identified that could keep the drink straw warm even under extremely cold conditions. Power requirements are not yet determined because the thermal environment inside the down suit relative to the external environment has not been established. A data logger will be used to track both the external and internal temperatures of the suit on a summit day.

  17. Radar Observations of Convective Systems from a High-Altitude Aircraft

    Science.gov (United States)

    Heymsfield, G.; Geerts, B.; Tian, L.

    1999-01-01

    Reflectivity data collected by the precipitation radar on board the tropical Rainfall Measuring Mission (TRMM) satellite, orbiting at 350 km altitude, are compared to reflectivity data collected nearly simultaneously by a doppler radar aboard the NASA ER-2 flying at 19-20 km altitude, i.e. above even the deepest convection. The TRMM precipitation radar is a scanning device with a ground swath width of 215 km, and has a resolution of about a4.4 km in the horizontal and 250 m in the vertical (125 m in the core swath 48 km wide). The TRMM radar has a wavelength of 217 cm (13.8 GHz) and the Nadir mirror echo below the surface is used to correct reflectivity for loss by attenuation. The ER-2 Doppler radar (EDOP) has two antennas, one pointing to the nadir, 34 degrees forward. The forward pointing beam receives both the normal and the cross-polarized echos, so the linear polarization ratio field can be monitored. EDOP has a wavelength of 3.12 cm (9.6 GHz), a vertical resolution of 37.5 m and a horizontal along-track resolution of about 100 m. The 2-D along track airflow field can be synthesized from the radial velocities of both beams, if a reflectivity-based hydrometer fall speed relation can be assumed. It is primarily the superb vertical resolution that distinguishes EDOP from other ground-based or airborne radars. Two experiments were conducted during 1998 into validate TRMM reflectivity data over convection and convectively-generated stratiform precipitation regions. The Teflun-A (TEXAS-Florida Underflight) experiment, was conducted in April and May and focused on mesoscale convective systems mainly in southeast Texas. TEFLUN-B was conducted in August-September in central Florida, in coordination with CAMEX-3 (Convection and Moisture Experiment). The latter was focused on hurricanes, especially during landfall, whereas TEFLUN-B concentrated on central; Florida convection, which is largely driven and organized by surface heating and ensuing sea breeze circulations

  18. A tow concept for the space shuttle orbiter approach and landing test

    Science.gov (United States)

    Bonner, T. F., Jr.; Pride, J. D., Jr.

    1976-01-01

    The tow concept provides the means for evaluating the orbiter aerodynamic performance and handling qualities in the same configuration as expected in actual space shuttle flight operation. A Boeing 747-100 aircraft has engine-out capability to tow the orbiter to an altitude that permits a safe orbiter approach and landing. The tow concept also provides a means for conducting a comprehensive ground test program before proceeding into the actual ALT flight operations. The implementation of the tow concept requires only a minor structural modification in the nose section of the orbiter vehicle; requires minor modifications in the 747 cargo bay; and makes use of those orbiter onboard systems installed in the ALT orbiter vehicle. The 747 wake turbulence does not constitute a problem for the orbiter during take-off or climb to altitude. The impact that the tow concept would have on the cost and schedule of the space shuttle program was not evaluated in this study.

  19. Acute high-altitude illness: a clinically orientated review

    OpenAIRE

    Smedley, Tom; Grocott, Michael PW

    2013-01-01

    Acute high-altitude illness is an encompassing term for the range of pathology that the unacclimatised individual can develop at increased altitude. This includes acute mountain sickness, high-altitude cerebral oedema and high-altitude pulmonary oedema. These conditions represent an increasing clinical problem as more individuals are exposed to the hypobaric hypoxic environment of high altitude for both work and leisure. In this review of acute high-altitude illness, the epidemiology, risk fa...

  20. High Altitude Clear Air Turbulence Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Air Force Flight Dynamics Laboratory conducted the High Altitude Clear Air Turbulence Project in the mid 1960s with the intention of better understanding air...

  1. Cosmic rays and dosimetry at aviation altitudes

    International Nuclear Information System (INIS)

    Recent concerns regarding the effects of the cosmic radiation field at aircraft altitudes on aircrew have resulted in a renewed interest in detailed measurements of the neutral and charged particle components in the atmosphere. CR-39 nuclear track detectors have been employed on a number of subsonic and supersonic aircraft to measure charge spectra and LET spectra at aircraft altitudes. These detectors are ideal for long term exposures required for these studies and their passive nature makes them suitable for an environment where interference with flight instrumentation could be a problem. We report here on measurements and analysis of short range tracks which were produced by high LET particles generated mainly by neutron interactions at aviation altitudes. In order to test the overall validity of the technique measurements were also carried out at the CERN-CEC field which simulates the radiation field at aviation altitudes and good agreement was found with dose values obtained using mainly heavy ion calibration

  2. High-altitude cerebral oedema mimicking stroke.

    Science.gov (United States)

    Yanamandra, Uday; Gupta, Amul; Patyal, Sagarika; Varma, Prem Prakash

    2014-01-01

    High-altitude cerebral oedema (HACO) is the most fatal high-altitude illness seen by rural physicians practising in high-altitude areas. HACO presents clinically with cerebellar ataxia, features of raised intracranial pressure (ICP) and coma. Early identification is important as delay in diagnosis can be fatal. We present two cases of HACO presenting with focal deficits mimicking stroke. The first patient presented with left-sided hemiplegia associated with the rapid deterioration in the sensorium. Neuroimaging revealed features suggestive of vasogenic oedema. The second patient presented with monoplegia of the lower limb. Neuroimaging revealed perfusion deficit in anterior cerebral artery territory. Both patients were managed with dexamethasone and they improved dramatically. Clinical picture and neuroimaging closely resembled acute ischaemic stroke in both cases. Thrombolysis in these patients would have been disastrous. Recent travel to high altitude, young age, absence of atherosclerotic risk factors and features of raised ICP concomitantly directed the diagnosis to HACO. PMID:24671373

  3. Blood Coagulation Changes at High Altitude

    Directory of Open Access Journals (Sweden)

    I. S. Chohan

    1984-10-01

    Full Text Available The current concepts of blood coagulation changes in the pathogenesis of acute mountain sickness (AMS, high altitude pulmonary oedema (HAPO, high altitude pulmonary hypertension (HAPH and chronic mountain sickness(CMS which afflict the inductees and residents at high altitude have been reviewed. Hypercoagulable state which is more marked during the first few days of exposure is countered by enhanced fibrinolytic activity and accelerated cell mediated immunity. Magnesium levels are increased in normal residents at high altitudes and may be responsible for enhancing fibrinolytic activity and accelerating immune responses. Magnesium levels are significantly reduced in HAPO patients. Judicious use of furosemide in lower dosage is still the mainstay of treatment of HAPO and AMS.

  4. Radiation doses at high altitudes and during space flights

    International Nuclear Information System (INIS)

    There are three main sources of radiation exposure during space flights and at high altitudes--galactic cosmic radiation, solar cosmic radiation and radiation of the earth's radiation belt. Their basic characteristics are presented in the first part of this paper.Man's exposure during space flights is discussed in the second part of the paper. Particular attention is devoted to the quantitative and qualitative characteristics of the radiation exposure on near-earth orbits: both theoretical estimation as well as experimental data are presented. Some remarks on radiation protection rules on-board space vehicles are also given.The problems connected with the radiation protection of air crew and passengers of subsonic and supersonic air transport are discussed in the last part of the paper. General characteristics of on-board radiation fields and their variations with flight altitude, geomagnetic parameters of a flight and the solar activity are presented, both based on theoretical estimates and experimental studies. The questions concerning air crew and passenger radiation protection arising after the publication of ICRP 60 recommendation are also discussed. Activities of different institutions relevant to the topic are mentioned; strategies to manage and check this type of radiation exposure are presented and discussed. Examples of results based on the author's personal experience are given, analyzed and discussed. (author)

  5. Python Engine Installed in Altitude Wind Tunnel

    Science.gov (United States)

    1949-01-01

    An engine mechanic checks instrumentation prior to an investigation of engine operating characteristics and thrust control of a large turboprop engine with counter-rotating propellers under high-altitude flight conditions in the 20-foot-dianieter test section of the Altitude Wind Tunnel at the Lewis Flight Propulsion Laboratory of the National Advisory Committee for Aeronautics, Cleveland, Ohio, now known as the John H. Glenn Research Center at Lewis Field.

  6. Pupillary Light Reaction during High Altitude Exposure

    OpenAIRE

    Schultheiss, Maximilian; Schommer, Kai; Schatz, Andreas; Wilhelm, Barbara; Peters, Tobias; Fischer, M. Dominik; Zrenner, Eberhart; Bartz-Schmidt, Karl U.; Gekeler, Florian; Willmann, Gabriel, 1977-

    2014-01-01

    Purpose This study aimed to quantify the pupillary light reaction during high altitude exposure using the state of the art Compact Integrated Pupillograph (CIP) and to investigate a potential correlation of altered pupil reaction with severity of acute mountain sickness (AMS). This work is related to the Tübingen High Altitude Ophthalmology (THAO) study. Methods Parameters of pupil dynamics (initial diameter, amplitude, relative amplitude, latency, constriction velocity) were quantified in 14...

  7. ACCELERATING POLARIZED PROTONS TO 250 GEV

    Energy Technology Data Exchange (ETDEWEB)

    BAI,M.; AHRENS, L.; ALEKSEEV, I.G.; ALESSI, J.; BEEBE-WANG, J.; ET AL.

    2007-06-25

    The Relativistic Heavy Ion Collider (RHIC) as the first high energy polarized proton collider was designed t o provide polarized proton collisions a t a maximum beam energy of 250 GeV. I t has been providing collisions a t a beam energy of 100 Gel' since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during the acceleration from injection to 100 GeV with careful control of the betatron tunes and the vertical orbit distortions. However, the intrinsic spin resonances beyond 100 GeV are about a factor of two stronger than those below 100 GeV? making it important t o examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were accelerated t o the record energy of 250 GeV in RHIC with a polarization of 46% measured a t top energy in 2006. The polarization measurement as a function of beam energy also shows some polarization loss around 136 GeV, the first strong intrinsic resonance above 100 GeV. This paper presents the results and discusses the sensitivity of the polarization survival t o orbit distortions.

  8. A gloss of Chronic Hypoxia in normal and diseased individuals at high altitude

    Institute of Scientific and Technical Information of China (English)

    Zubieta-Castillo,G.; Zubieta-Calleja,G.R.; Zubieta-Calleja L.

    2004-01-01

    @@ Introduction Millenary populations that live at high altitude in different continents like Asia (1) and South America (8), have endured biological adaptation in very adverse environmental conditions, of which to our understanding, paradoxically, chronic hypoxia is the most tolerable. Patients with pulmonary diseases at high altitude tolerate tissue hypoxia with an arterial tension (PaO2) even as low as 30 mmHg. Current scientific knowledge has made progress in many areas, clarifying many doubts, however due to preconception and lack of broad social studies chronic hypoxia is still not fully understood. Beings that inhabit different areas of the planet earth have lived under a variety of different hostile conditions: intense cold in the polar regions,intense heat in Africa and in the Middle East desserts,great pressure in the depth of the oceans, intense darkness of the caves and naturally the hypoxia of extreme altitudes.

  9. Characteristics of trapped proton anisotropy at Space Station Freedom altitudes

    Science.gov (United States)

    Armstrong, T. W.; Colborn, B. L.; Watts, J. W.

    1990-01-01

    The ionizing radiation dose for spacecraft in low-Earth orbit (LEO) is produced mainly by protons trapped in the Earth's magnetic field. Current data bases describing this trapped radiation environment assume the protons to have an isotropic angular distribution, although the fluxes are actually highly anisotropic in LEO. The general nature of this directionality is understood theoretically and has been observed by several satellites. The anisotropy of the trapped proton exposure has not been an important practical consideration for most previous LEO missions because the random spacecraft orientation during passage through the radiation belt 'averages out' the anisotropy. Thus, in spite of the actual exposure anisotropy, cumulative radiation effects over many orbits can be predicted as if the environment were isotropic when the spacecraft orientation is variable during exposure. However, Space Station Freedom will be gravity gradient stabilized to reduce drag, and, due to this fixed orientation, the cumulative incident proton flux will remain anisotropic. The anisotropy could potentially influence several aspects of Space Station design and operation, such as the appropriate location for radiation sensitive components and experiments, location of workstations and sleeping quarters, and the design and placement of radiation monitors. Also, on-board mass could possible be utilized to counteract the anisotropy effects and reduce the dose exposure. Until recently only omnidirectional data bases for the trapped proton environment were available. However, a method to predict orbit-average, angular dependent ('vector') trapped proton flux spectra has been developed from the standard omnidirectional trapped proton data bases. This method was used to characterize the trapped proton anisotropy for the Space Station orbit (28.5 degree inclination, circular) in terms of its dependence on altitude, solar cycle modulation (solar minimum vs. solar maximum), shielding thickness

  10. BLOCKING SUN WITH ORBITING BALLOONS

    Energy Technology Data Exchange (ETDEWEB)

    Chul Park [Department of Aerospace Engineering, Kor ea Advanced Institute of Science and Technology, Daejeon (Korea)

    2008-09-30

    Sun's radiation power reaching Earth's surface can be reduced by letting large balloons circle the Earth in orbits at approximately 1000 km altitude. These balloons, made of plastic films 1 mm in thickness, of a diameter of approximately 46 km, will weigh about 10,000 tons each. A balloon will consist of one hundred of 100 ton pieces. They are transported to the orbit piece by piece, and are assembled there into the spherical shape. They are kept inflated with the vapor pressure of potassium and the electrostatic forces. The inclination angles of these balloons with respect to the solar ecliptic plane can be varied from zero to 90 degrees, although efficiency is highest with the zero degree inclination. If zero degree inclination is chosen, twenty-three of these will reduce the average sun's radiation by 0.01%. In the 1000 km orbits, which are stable and are populated only by space debris, these balloons will serve also to remove the debris.

  11. Child health and living at high altitude.

    Science.gov (United States)

    Niermeyer, S; Andrade Mollinedo, P; Huicho, L

    2009-10-01

    The health of children born and living at high altitude is shaped not only by the low-oxygen environment, but also by population ancestry and sociocultural determinants. High altitude and the corresponding reduction in oxygen delivery during pregnancy result in lower birth weight with higher elevation. Children living at high elevations are at special risk for hypoxaemia during infancy and during acute lower respiratory infection, symptomatic high-altitude pulmonary hypertension, persistence of fetal vascular connections, and re-entry high-altitude pulmonary oedema. However, child health varies from one population group to another due to genetic adaptation as well as factors such as nutrition, intercurrent infection, exposure to pollutants and toxins, socioeconomic status, and access to medical care. Awareness of the risks uniquely associated with living at high altitude and monitoring of key health indicators can help protect the health of children at high altitude. These considerations should be incorporated into the scaling-up of effective interventions for improving global child health and survival. PMID:19066173

  12. Field-aligned currents in the dayside cusp and polar cap region during northward IMF

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Moretto, T.; Olsen, Nils;

    2002-01-01

    [1] The field-aligned currents in the dayside cusp and polar cap region are examined using magnetic data from the low-altitude polar-orbiting satellite Orsted. The study is confined to cases where the interplanetary magnetic field (IMF) has a steady northward component and to a rather narrow region...... spanning similar to 4 hours around magnetic noon. We examine individual passes using a maximum variance analysis method, and we complement, for a single event, with ground-based data from the Greenland meridian chain of magnetometers. We suggest that when an east-west component B-y of the IMF exists...... for positive IMF B-z, the two NBZ (northward B-z) field-aligned currents that prevail over the polar region rotate to form the two field-aligned currents equatorward and poleward of the east-west flowing ionospheric DPY current in the dayside. The high accuracy of the Orsted data makes it possible to uncover...

  13. Physiological aspects of altitude training and the use of altitude simulators

    Directory of Open Access Journals (Sweden)

    Ranković Goran

    2005-01-01

    Full Text Available Altitude training in various forms is widely practiced by athletes and coaches in an attempt to improve sea level endurance. Training at high altitude may improve performance at sea level through altitude acclimatization, which improves oxygen transport and/or utilization, or through hypoxia, which intensifies the training stimulus. This basic physiological aspect allows three training modalities: live high and train high (classic high-altitude training, live low and train high (training through hypoxia, and live high and train low (the new trend. In an effort to reduce the financial and logistical challenges of traveling to high-altitude training sites, scientists and manufactures have developed artificial high-altitude environments, which simulate the hypoxic conditions of moderate altitude (2000-3000 meters. Endurance athletes from many sports have recently started using nitrogen environments, or hypoxic rooms and tents as part of their altitude training programmes. The results of controlled studies on these modalities of high-altitude training, their practical approach, and ethics are summarized.

  14. Haematological Studies in High Altitude Natives at Plains and on Return to High Altitude

    OpenAIRE

    Jain, S C; H. M. Divekar; Jaya Bardhan; R S Sharma; Swamy, Y. V.

    1988-01-01

    Haematologic studies were carried out in 20 high altitude natives during two months stay at plains (200 m) and on their return to an altitude of 3,500 m. Haemoglobin, erythrocyte count, haematocrit and reticulocyte count decreased rapidly on arrival to plains and attained minimum level by the end of fourth week. All these parameters increased rapidly on return to high altitude and were found to attain maximum values by 23rd day on return to high altitude. Mean cell volume and mean cell haemog...

  15. Interpretation of CHAMP magnetic anomaly data over the Pannonian Basin region using lower altitude and gradient data

    International Nuclear Information System (INIS)

    Complete text of publication follows. In 2005 (Taylor et al., 2005-Earth Observation with CHAMP Results from Three Years in Orbit) computed and interpreted a CHAMP satellite magnetic anomaly map, at 400 km altitude, over the Pannonian Basin and surrounding region using the method of Alsdorf et al. (1994). This area was chosen since it has one of the thinnest continental crusts in Europe and is the region of complex tectonic structures. The future SWARM satellite constellation of three spacecraft, with one at a high altitude and the other two lower, will initially be at the same altitude as CHAMP but eventually they will descent to a lower altitude. We recomputed our most recent satellite magnetic anomaly map, using the spherical-cap method of Haines (1985), the technique of Alsdorf et al. (1994) and from spherical harmonic coefficients of MF6 (Maus et al., 2008) employing the latest and lowest altitude CHAMP data, in order to evaluate and reinterpret these newer data to determine the advantage of lower altitude satellite data. The SWARM constellation will have the two lowest altitude satellites flying abreast, with a separation of between ca. 150 to 200 km. to record the horizontal magnetic gradient. Since the CHAMP satellite has been in orbit for eight years and has obtained an extensive range of data, both vertically and horizontally there is a large enough data base to compute the magnetic gradients over the Pannonian Basin region using the many orbits. We computed the magnetic anomaly gradients in order to determine how these component data will improve our interpretation and to preview what the SWARM mission will reveal with reference to the horizontal gradient anomalies.

  16. Solar Cell Short Circuit Current Errors and Uncertainties During High Altitude Calibrations

    Science.gov (United States)

    Snyder, David D.

    2012-01-01

    High altitude balloon based facilities can make solar cell calibration measurements above 99.5% of the atmosphere to use for adjusting laboratory solar simulators. While close to on-orbit illumination, the small attenuation to the spectra may result in under measurements of solar cell parameters. Variations of stratospheric weather, may produce flight-to-flight measurement variations. To support the NSCAP effort, this work quantifies some of the effects on solar cell short circuit current (Isc) measurements on triple junction sub-cells. This work looks at several types of high altitude methods, direct high altitude meas urements near 120 kft, and lower stratospheric Langley plots from aircraft. It also looks at Langley extrapolation from altitudes above most of the ozone, for potential small balloon payloads. A convolution of the sub-cell spectral response with the standard solar spectrum modified by several absorption processes is used to determine the relative change from AMO, lscllsc(AMO). Rayleigh scattering, molecular scatterin g from uniformly mixed gases, Ozone, and water vapor, are included in this analysis. A range of atmosph eric pressures are examined, from 0. 05 to 0.25 Atm to cover the range of atmospheric altitudes where solar cell calibrations a reperformed. Generally these errors and uncertainties are less than 0.2%

  17. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

    Current research into holography is concerned with applications in optically storing, retrieving, and processing information. Polarization holography has many unique properties compared to conventional holography. It gives results in high efficiency, achromaticity, and special polarization...... properties. This books reviews the research carried out in this field over the last 15 years. The authors provide basic concepts in polarization and the propagation of light through anisotropic materials, before presenting a sound theoretical basis for polarization holography. The fabrication and...... characterization of azobenzene based materials, which remain the most efficient for the purpose, is described in detail. This is followed by a description of other materials that are used in polarization holography. An in-depth description of various applications, including display holography and optical storage...

  18. Updates in Orbital Tumors

    Institute of Scientific and Technical Information of China (English)

    Nila; F.Moeloek

    1993-01-01

    Orbital anatomy, the clinical features of orbital tumors, the recent development of the diagnosis and management of orbital tumors were described. The incidence of orbital tumors in Dr. Cipto Mangunkusumo Hospital in the past years were introduced. The principle of management of orbital tumors and their prognosis were discussed.

  19. Neutral Wind Observations below 200 km altitudes

    Science.gov (United States)

    Watanabe, S.; Abe, T.; Habu, H.; Kakinami, Y.; Larsen, M. F.; Pfaff, R. F., Jr.; Yamamoto, M.

    2015-12-01

    Neutral Wind Observations below 200 km altitudesS. Watanabe1, T. Abe2, H. Habu2, Y. Kakinami3, M. Larsen4, R. Pfaff5, M. Yamamoto6, M-Y. Yamamoto31Hokkaido University/Hokkaido Information University, 2JAXA/ISAS, 3Kochi University of Technology, 4Clemson University, 5NASA/Goddard Space Flight Center, 6Kyoto University, Neutral wind in the thermosphere is one of the key parameters to understand the ionosphere-thermosphere coupling process. JAXA/ISAS successfully launched sounding rockets from Uchinoura Space Center (USC) on September 2, 2007, January 12, 2012, and July 20, 2013, and NASA launched sounding rockets from Kwajalein on May 7, 2013 and from Wallops on July 4, 2013. The rockets installed Lithium and/or TMA canisters as well as instruments for plasma and electric and magnetic fields. The atomic Lithium gases were released at altitudes between 150 km and 300 km in the evening on September 2, 2007, at altitude of ~100 km in the morning on January 12, 2012, at altitude of ~120km in the midnight on July 20, 2013, at altitude between 150 km and 300 km in the evening on May 7, 2013 and at altitude of ~150 km in the noon on July 4, 2013. The Lithium atoms were scattering sunlight by resonance scattering with wavelength of 670nm. However, the Lithium atoms scattered moon light on July 20, 2013. The moon light scattering is the first time to use for thermospheric wind measurement in the midnight. The Lithium clouds/trails and TMA trails showed clearly the neutral wind shears and atmospheric waves at ~150 km altitude in the lower thermosphere for all local time.

  20. Imaging of Orbital Infections

    Directory of Open Access Journals (Sweden)

    Seyed Hassan Mostafavi

    2010-05-01

    Full Text Available Preseptal and orbital cellulitis occur more commonly in children than adults. The history and physical examination are crucial in distinguishing between preseptal and orbital cellulitis. The orbital septum delineates the anterior eyelid soft tissues from the orbital soft tissue. Infections anterior to the orbital septum are classified as preseptal cellulitis and those posterior to the orbital septum are termed orbital cellulitis. "nRecognition of orbital involvement is important not only because of the threatened vision loss associated with orbital cellulitis but also because of the potential for central nervous system complications including cavernous sinus thrombosis, meningitis, and death. "nOrbital imaging should be obtained in all patients suspected of having orbital cellulitis. CT is preferred to MR imaging, as the orbital tissues have high con-trast and the bone can be well visualized. Orbital CT scanning allows localization of the disease process to the preseptal area, the extraconal or intraconal fat, or the subperiosteal space. Axial CT views allow evaluation of the medial orbit and ethmoid sinuses, whereas coronal scans image the orbital roof and floor and the frontal and maxillary sinuses. If direct coronal imaging is not possible, reconstruction of thin axial cuts may help the assessment of the orbital roof and floor. Potential sources of orbital cellulitis such as sinusitis, dental infection, and facial cellulitis are often detectable on CT imaging. "nIn this presentation, the imaging considerations of the orbital infections; including imaging differentiation criteria of all types of orbital infections are reviewed.

  1. Generation and detection of orbital angular momentum via metasurface

    OpenAIRE

    Jin, Jinjin; Luo, Jun; Zhang, Xiaohu; Gao, Hui; Li, Xiong; Pu, Mingbo; Gao, Ping; Zhao, Zeyu; Luo, Xiangang

    2016-01-01

    Beams carrying orbital angular momentum possess a significant potential for modern optical technologies ranging from classical and quantum communication to optical manipulation. In this paper, we theoretically design and experimentally demonstrate an ultracompact array of elliptical nanoholes, which could convert the circularly polarized light into the cross-polarized vortex beam. To measure the topological charges of orbital angular momentum in a simple manner, another elliptical nanoholes a...

  2. Spin-to-Orbital Angular Momentum Conversion in Semiconductor Microcavities

    OpenAIRE

    Manni, Francesco; Lagoudakis, Konstantinos G.; Paraïso, Taofiq; Cerna, Roland; Léger, Yoan; Liew, Timothy Chi Hin; Shelykh, Ivan; Kavokin, Alexey V.; Morier-Genoud, François; Deveaud-Plédran, Benoît

    2011-01-01

    We experimentally demonstrate a technique for the generation of optical beams carrying orbital angular momentum using a planar semiconductor microcavity. Despite being isotropic systems with no structural gyrotropy, semiconductor microcavities, because of the transverse-electric–transverse-magnetic polarization splitting that they feature, allow for the conversion of the circular polarization of an incoming laser beam into the orbital angular momentum of the transmitted light field. The proce...

  3. Polarized electroproduction

    International Nuclear Information System (INIS)

    A new type of information on proton structure, its internal spin structure, has recently become available from a new type of experiment, polarized electroproduction. The scattering of longitudinally polarized electrons was measured by longitudinally polarized protons. The quantity measured was the asymmetry A, the normalized difference between the differential scattering cross sections for the antiparallel and parallel spin configurations. Data have been obtained for elastic, deep inelastic, and reasonance region scattering. Polarized electrons were obtained by the photoionization of polarized Li atomic beam with pulsed UV light. The important characteristics of the polarized electron beam are the intensity of 109 e-/1.5 μs pulse at repetition rate of 120 pps, and polarization of 0.85 +- 0.08. A number of data on deep inelastic scattering, preliminary asymmetry in the resonance region and others are described and illustrated in several graphs. There are several implications in these data; 1) test of Bjorken sum rule, 2) scaling, and 3) models of proton structure, which are mentioned hereinafter. The Bjorken sum rule predicts equality in the scaling limit between an integral over ω of the product of spin-averaged nucleon structure function W2 and spin dependent function A, and the ratio of axial vector to vector weak coupling constants of beta decay. Data on the asymmetries in deep inelastic and resonance region scattering will make possible the evaluation of a famous old problem -- the effect of proton polarizability on the hyperfine structure interval in hydrogen. (Wakatsuki, Y.)

  4. Achromatic orbital angular momentum generator

    International Nuclear Information System (INIS)

    We describe a novel approach for generating light beams that carry orbital angular momentum (OAM) by means of total internal reflection in an isotropic medium. A continuous space-varying cylindrically symmetric reflector, in the form of two glued hollow axicons, is used to introduce a nonuniform rotation of polarization into a linearly polarized input beam. This device acts as a full spin-to-orbital angular momentum convertor. It functions by switching the helicity of the incoming beam's polarization, and by conservation of total angular momentum thereby generates a well-defined value of OAM. Our device is broadband, since the phase shift due to total internal reflection is nearly independent of wavelength. We verify the broad-band behaviour by measuring the conversion efficiency of the device for three different wavelengths corresponding to the RGB colours, red, green and blue. An average conversion efficiency of 95% for these three different wavelengths is observed. This device may find applications in imaging from micro- to astronomical systems where a white vortex beam is needed. (paper)

  5. The Impact of Altitude on Infant Health in South America

    OpenAIRE

    Wehby, George L; Eduardo E. Castilla; Lopez-Camelo, Jorge

    2010-01-01

    Previous Studies have reported that altitude reduces birth weight in South America. However, much remains unknown about the heterogeneities in altitude effects by fetal health endowments and about the effects in various ranges of altitude. This study estimates the effects of altitude on the means and quantiles of birth weight and gestational age separately for two large samples o...

  6. HIGH ALTITUDE TESTING OF RESIDENTIAL WOOD-FIRED COMBUSTION EQUIPMENT

    Science.gov (United States)

    To determine whether emissions from operating a wood stove at high altitude differ from those at low altitude, a high altitude sampling program was conducted which was compared to previously collected low altitude data. Emission tests were conducted in the identical model stove u...

  7. Targeting Low-Energy Transfers to Low Lunar Orbit

    Science.gov (United States)

    Parker, Jeffrey S.; Anderson, Rodney L.

    2011-01-01

    A targeting scheme is presented to build trajectories from a specified Earth parking orbit to a specified low lunar orbit via a low-energy transfer and up to two maneuvers. The total transfer delta V (velocity) is characterized as a function of the Earth parking orbit inclination and the departure date for transfers to each given low lunar orbit. The transfer delta V (velocity) cost is characterized for transfers constructed to low lunar polar orbits with any longitude of ascending node and for transfers that arrive at the Moon at any given time during a month.

  8. High altitude pulmonary edema in mountain climbers.

    Science.gov (United States)

    Korzeniewski, Krzysztof; Nitsch-Osuch, Aneta; Guzek, Aneta; Juszczak, Dariusz

    2015-04-01

    Every year thousands of ski, trekking or climbing fans travel to the mountains where they stay at the altitude of more than 2500-3000m above sea level or climb mountain peaks, often exceeding 7000-8000m. High mountain climbers are at a serious risk from the effects of adverse environmental conditions prevailing at higher elevations. They may experience health problems resulting from hypotension, hypoxia or exposure to low temperatures; the severity of those conditions is largely dependent on elevation, time of exposure as well as the rate of ascent and descent. A disease which poses a direct threat to the lives of mountain climbers is high altitude pulmonary edema (HAPE). It is a non-cardiogenic pulmonary edema which typically occurs in rapidly climbing unacclimatized lowlanders usually within 2-4 days of ascent above 2500-3000m. It is the most common cause of death resulting from the exposure to high altitude. The risk of HAPE rises with increased altitude and faster ascent. HAPE incidence ranges from an estimated 0.01% to 15.5%. Climbers with a previous history of HAPE, who ascent rapidly above 4500m have a 60% chance of illness recurrence. The aim of this article was to present the relevant details concerning epidemiology, pathophysiology, clinical symptoms, prevention, and treatment of high altitude pulmonary edema among climbers in the mountain environment. PMID:25291181

  9. Patients with Obstructive Sleep Apnea at Altitude.

    Science.gov (United States)

    Bloch, Konrad E; Latshang, Tsogyal D; Ulrich, Silvia

    2015-06-01

    Bloch, Konrad E., Tsogyal D. Latshang, and Silvia Ulrich. Patients with obstructive sleep apnea at altitude. High Alt Med Biol 16:110-116, 2015.--Obstructive sleep apnea (OSA) is highly prevalent in the general population, in particular in men and women of older age. In OSA patients sleeping near sea level, the apneas/hypopneas associated with intermittent hypoxemia are predominantly due to upper airway collapse. When OSA patients stay at altitudes above 1600 m, corresponding to that of many tourist destinations, hypobaric hypoxia promotes frequent central apneas in addition to obstructive events, resulting in combined intermittent and sustained hypoxia. This induces strong sympathetic activation with elevated heart rate, cardiac arrhythmia, and systemic hypertension. There are concerns that these changes expose susceptible OSA patients, in particular those with advanced age and co-morbidities, to an excessive risk of cardiovascular and other adverse events during a stay at altitude. Based on data from randomized trials, it seems advisable for OSA patients to use continuous positive airway pressure treatment with computer controlled mask pressure adjustment (autoCPAP) in combination with acetazolamide during an altitude sojourn. If CPAP therapy is not feasible, acetazolamide alone is better than no treatment at all, as it improves oxygenation and sleep apnea and prevents excessive blood pressure rises of OSA patients at altitude. PMID:25973669

  10. Responses of the autonomic nervous system in altitude adapted and high altitude pulmonary oedema subjects

    Science.gov (United States)

    Mathew, Lazar; Purkayastha, S. S.; Jayashankar, A.; Radhakrishnan, U.; Sen Gupta, J.; Nayar, H. S.

    1985-06-01

    Studies were carried out to ascertain the role of sympatho-parasympathetic responses in the process of adaptation to altitude. The assessment of status of autonomic balance was carried out in a group of 20 young male subjects by recording their resting heart rate, blood pressure, oral temperature, mean skin temperature, extremity temperatures, pupillary diameter, cold pressor response, oxygen consumption, cardioacceleration during orthostasis and urinary excretion of catecholamines; in a thermoneutral laboratory. The same parameters were repeated on day 3 and at weekly intervals for a period of 3 weeks, after exposing them to 3,500 m; and also after return to sea level. At altitude, similar studies were carried out in a group of 10 acclimatized lowlanders, 10 high altitude natives and 6 patients who had recently recovered from high altitude pulmonary oedema. In another phase, similar studies were done in two groups of subjects, one representing 15 subjects who had stayed at altitude (3,500 4,000 m) without any ill effects and the other comprising of 10 subjects who had either suffered from high altitude pulmonary oedema (HAPO) or acute mountain sickness (AMS). The results revealed sympathetic overactivity on acute induction to altitude which showed gradual recovery on prolonged stay, the high altitude natives had preponderance to parasympathetic system. Sympathetic preponderance may not be an essential etiological factor for the causation of maladaptation syndromes.

  11. Contribution of the Argos System for the study of the polar regions

    International Nuclear Information System (INIS)

    The Argos data collection and location system, aboard the NOAA polar orbiters, has been used by many scientists studying the polar regions. This paper will describe the latest improvements in this, the first worldwide operational location system, and summarize some applications of the Argos System developed by North American users in the polar regions. Arctic applications include drifting buoy collection of meteorological and/or oceanographic data to support operational programs using the ice as a research platform. Antarctic applications include environmental research for a better understanding of microbial ecosystems; winter data acquisition on ice motion using parachute-dropped buoys; oceanographic drifters to support operational and research programs; automatic weather and geophysical stations; high-altitude balloon experiments to observe supernovas; long-duration balloon experiments to collect data on stratospheric winds; tracking movements of fur and Weddell seals, and penguins. The applications described above were made possible by specific characteristics and capabilities of the Argos System: systematic polar coverage; two operational satellites since 1979 and probably continuing after the year 2000; near-realtime data availability for platforms within the footprint of the NOAA Fairbanks ground station during every satellite pass; data provided directly to the user's own PC upon request or available in the two redundant data processing centers (Toulouse, France and Landover, Maryland, US) 24 hours a day through data transmission networks; location accuracy of 150 m. Argos-compatible instruments have been designed by numerous governmental and private organizations to operate in the harsh polar environment and to take advantage of the unique platform provided by the ice. The Argos System will continue to provide operational and reliable environmental location and data

  12. Parton Distributions and Spin-Orbital Correlations

    International Nuclear Information System (INIS)

    In this talk, I summarize a recent study showing that the large-x parton distributions contain important information on the quark orbital angular momentum of nucleon. This contribution could explain the conflict between the experimental data and the theory predictions for the polarized quark distributions. Future experiments at JLab shall provide further test for our predictions

  13. Anomalous Hall conductivity: Local orbitals approach

    Czech Academy of Sciences Publication Activity Database

    Středa, Pavel

    2010-01-01

    Roč. 82, č. 4 (2010), 045115/1-045115/9. ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100521 Keywords : anomalous Hall effect * Berry phase correction * orbital polarization momentum Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.772, year: 2010

  14. Mesoscopic Rings with Spin-Orbit Interactions

    Science.gov (United States)

    Berche, Bertrand; Chatelain, Christophe; Medina, Ernesto

    2010-01-01

    A didactic description of charge and spin equilibrium currents on mesoscopic rings in the presence of spin-orbit interaction is presented. Emphasis is made on the non-trivial construction of the correct Hamiltonian in polar coordinates, the calculation of eigenvalues and eigenfunctions and the symmetries of the ground-state properties. Spin…

  15. Correlation of Lunar South Polar Epithermal Neutron Maps: Lunar Exploration Neutron Detector and Lunar Prospector Neutron Detector

    Science.gov (United States)

    McClanahan, Timothy P.; Mitrofanov, I. G.; Boynton, W. V.; Sagdeev, R.; Trombka, J. I.; Starr, R. D.; Evans, L. G.; Litvak, M. L.; Chin, G.; Garvin, J.; Sanin, A. B.; Malakhov, A.; Milikh, G. M.; Harshman, K.; Finch, M. J.; Nandikotkur, G.

    2010-01-01

    The Lunar Reconnaissance Orbiter's (LRO), Lunar Exploration Neutron Detector (LEND) was developed to refine the lunar surface hydrogen (H) measurements generated by the Lunar Prospector Neutron Spectrometer. LPNS measurements indicated a approx.4,6% decrease in polar epithermal fluxes equivalent to (1.5+/-0,8)% H concentration and are direct geochemical evidence indicating water /high H at the poles. Given the similar operational and instrumental objectives of the LEND and LPNS systems, an important science analysis step for LEND is to test correlation with existing research including LPNS measurements. In this analysis, we compare corrected low altitude epithermal rate data from LPNS available via NASA's Planetary Data System (PDS) with calibrated LEND epithermal maps using a cross-correlation technique

  16. GPS/Galileo navigation in GTO/GEO orbit

    Science.gov (United States)

    Marmet, François-Xavier; Maureau, Jerome; Calaprice, Massimiliano; Aguttes, Jean Paul

    2015-12-01

    The development of electrically propelled geostationary platforms, together with alternative strategies to reach geostationary orbit, increase the interest for autonomous satellite localization and particularly GNSS navigation for high altitude orbits. It is known that GNSS navigation in GTO/GEO is much more difficult than in LEO since the GNSS receiver is often or permanently at an altitude greater than the altitude of the GNSS constellations, making the GNSS signals drastically less available and weaker. This work is about GPS and Galileo navigation on GEO and GTO orbits, with revised hypotheses compared to studies sometimes more than 15 years old. Moreover, the study goes beyond GNSS geometrical visibility by dealing with operating thresholds and showing the sensitivity to key GNSS receiver thresholds and simulation hypotheses. Comprehensive simulation results and analyses come along with a discussion of the operational benefits of using GPS and Galileo navigation. These data eventually set the ground for a discussion of the key technical options (number and antenna types, GNSS function architecture, signal processing algorithms, orbital filter…). It is shown that using GNSS for GTOGEO orbits is feasible, even considering current spaceborne receivers state-of-the-art, and provides most of the acclaimed benefits of GNSS in LEO, among them more accurate spacecraft localization, precise onboard absolute time and increased autonomy.

  17. DKIST Polarization Modeling and Performance Predictions

    Science.gov (United States)

    Harrington, David

    2016-05-01

    Calibrating the Mueller matrices of large aperture telescopes and associated coude instrumentation requires astronomical sources and several modeling assumptions to predict the behavior of the system polarization with field of view, altitude, azimuth and wavelength. The Daniel K Inouye Solar Telescope (DKIST) polarimetric instrumentation requires very high accuracy calibration of a complex coude path with an off-axis f/2 primary mirror, time dependent optical configurations and substantial field of view. Polarization predictions across a diversity of optical configurations, tracking scenarios, slit geometries and vendor coating formulations are critical to both construction and contined operations efforts. Recent daytime sky based polarization calibrations of the 4m AEOS telescope and HiVIS spectropolarimeter on Haleakala have provided system Mueller matrices over full telescope articulation for a 15-reflection coude system. AEOS and HiVIS are a DKIST analog with a many-fold coude optical feed and similar mirror coatings creating 100% polarization cross-talk with altitude, azimuth and wavelength. Polarization modeling predictions using Zemax have successfully matched the altitude-azimuth-wavelength dependence on HiVIS with the few percent amplitude limitations of several instrument artifacts. Polarization predictions for coude beam paths depend greatly on modeling the angle-of-incidence dependences in powered optics and the mirror coating formulations. A 6 month HiVIS daytime sky calibration plan has been analyzed for accuracy under a wide range of sky conditions and data analysis algorithms. Predictions of polarimetric performance for the DKIST first-light instrumentation suite have been created under a range of configurations. These new modeling tools and polarization predictions have substantial impact for the design, fabrication and calibration process in the presence of manufacturing issues, science use-case requirements and ultimate system calibration

  18. Effects of Ascent to High Altitude on Human Antimycobacterial Immunity

    OpenAIRE

    Eisen, S; Pealing, L.; Aldridge, RW; Siedner, MJ; Necochea, A.; Leybell, I.; Valencia, T; Herrera, B.; Wiles, S; Friedland, JS; Gilman, RH; Evans, CA

    2013-01-01

    BACKGROUND: Tuberculosis infection, disease and mortality are all less common at high than low altitude and ascent to high altitude was historically recommended for treatment. The immunological and mycobacterial mechanisms underlying the association between altitude and tuberculosis are unclear. We studied the effects of altitude on mycobacteria and antimycobacterial immunity. METHODS: Antimycobacterial immunity was assayed in 15 healthy adults residing at low altitude before and after they a...

  19. Sonic Thermometer for High-Altitude Balloons

    Science.gov (United States)

    Bognar, John

    2012-01-01

    The sonic thermometer is a specialized application of well-known sonic anemometer technology. Adaptations have been made to the circuit, including the addition of supporting sensors, which enable its use in the high-altitude environment and in non-air gas mixtures. There is a need to measure gas temperatures inside and outside of superpressure balloons that are flown at high altitudes. These measurements will allow the performance of the balloon to be modeled more accurately, leading to better flight performance. Small thermistors (solid-state temperature sensors) have been used for this general purpose, and for temperature measurements on radiosondes. A disadvantage to thermistors and other physical (as distinct from sonic) temperature sensors is that they are subject to solar heating errors when they are exposed to the Sun, and this leads to issues with their use in a very high-altitude environment

  20. Hermes Global Orbiter: A Discovery Mission in Gestation

    Science.gov (United States)

    Nelson, R. M.; Horn, L. J.; Weiss, J. R.; Smythe, W. D.

    1994-01-01

    The hermes Global Orbiter (HGO) is a Discovery class mission under study, which is investigating the possibility of placing a small spacecraft in highly elliptical polar orbit about mercury. The purpose of the mission is to conduct observations of the planet's surface, atmosphere and magnetosphere.

  1. Mars orbiter redirected in bid to find Beagle

    CERN Multimedia

    2003-01-01

    "Mission controllers in Darmstadt, Germany, have successfully redirected Europe's Mars Express orbiter into a polar orbit, putting it on course for a last-ditch attempt to contact Beagle 2, the lander that has been missing since Christmas day when it should have touched down on the red planet" (1/2 page).

  2. Cosmic Background Explorer (COBE) transfer orbit attitude control system

    Science.gov (United States)

    Placanica, Samuel J.; Flatley, Thomas W.

    1986-01-01

    The Cosmic Background Explorer (COBE) spacecraft will be launched by the Shuttle from Vandenberg AFB into a 300 km altitude, 99 deg inclination, 6 a.m. or 6 p.m. ascending node orbit. After release from the Remote Manipulator System (RMS) arm, an on-board monopropellant hydrazine propulsion system will raise the orbit altitude to 900 km. The spacecraft continuously spins during transfer orbit operations with the spin axis nominally horizontal and in or near the orbit plane. The blowdown propulsion system consists of twelve 5 lb thrusters (3 'spin', 3 'despin', and 6 'axial') with the latter providing initially 30 lb of force parallel to the spin axis for orbit raising. The spin/despin jets provide a constant roll rate during the transfer orbit phase of the mission and the axials control pitch and yaw. The axial thrusters are pulsed on for attitude control during coast periods and are normally on- and off-modulated for control during orbit raising. Attitude sensors employed in the control loops include an array of two-axis digital sun sensors and three planar earth scanners for position measurements, as well as six gyroscopes for rate information. System redundancy is achieved by means of unique three-axes-in-a-plane geometry. This triaxial concept results in a fail-safe operational system with no performance degradation for many different component failure modes.

  3. Atmospheric electron flux at airplane altitude

    International Nuclear Information System (INIS)

    We have developed a new detector to systematically measure the cosmic-ray electron flux at airplane altitudes. We loaded a lead-glass-based electron telescope onto a commercial cargo airplane. The first experiment was carried out using the air route between Narita (Japan) and Sydney (Australia); during this flight we measured the electron flux at various altitudes and latitudes. The thresholds of the electron energies were 1, 2, and 4 GeV. The results agree with a simple estimation using one-dimensional shower theory. A comparison with a Monte Carlo calculation was made

  4. Solar Array Disturbances to Spacecraft Pointing During the Lunar Reconnaissance Orbiter (LRO) Mission

    Science.gov (United States)

    Calhoun, Philip

    2010-01-01

    The Lunar Reconnaissance Orbiter (LRO), the first spacecraft to support NASA s return to the Moon, launched on June 18, 2009 from the Cape Canaveral Air Force Station aboard an Atlas V launch vehicle. It was initially inserted into a direct trans-lunar trajectory to the Moon. After a five day transit to the Moon, LRO was inserted into the Lunar orbit and successfully lowered to a low altitude elliptical polar orbit for spacecraft commissioning. Successful commissioning was completed in October 2009 when LRO was placed in its near circular mission orbit with an approximate altitude of 50km. LRO will spend at least one year orbiting the Moon, collecting lunar environment science and mapping data, utilizing a suite of seven instruments to enable future human exploration. The objective is to provide key science data necessary to facilitate human return to the Moon as well as identification of opportunities for future science missions. LRO's instrument suite will provide the high resolution imaging data with sub-meter accuracy, highly accurate lunar cartographic maps, mineralogy mapping, amongst other science data of interest. LRO employs a 3-axis stabilized attitude control system (ACS) whose primary control mode, the "Observing Mode", provides Lunar nadir, off-nadir, and inertial fine pointing for the science data collection and instrument calibration. This controller combines the capability of fine pointing with on-demand large angle full-sky attitude reorientation. It provides simplicity of spacecraft operation as well as additional flexibility for science data collection. A conventional suite of ACS components is employed in the Observing Mode to meet the pointing and control objectives. Actuation is provided by a set of four reaction wheels developed in-house at NASA Goddard Space Flight Center (GSFC). Attitude feedback is provided by a six state Kalman filter which utilizes two SELEX Galileo Star Trackers for attitude updates, and a single Honeywell Miniature

  5. High spin polarization at the HERA electron storage ring

    International Nuclear Information System (INIS)

    This paper describes the progress made in 1992 towards increasing the vertical electron beam polarization at HERA. Utilizing harmonic spin-orbit corrections and beam tuning, the vertical polarization has been increased from 15% to nearly 60% at a beam energy of 26.7 GeV. The long-term reproducibility of the polarization is excellent. Measurements of the build-up time and the energy dependence of the polarization are also described. (orig.)

  6. A user's guide to locating flux transfer events in low-altitude satellite measurements: An S3-2 case study

    International Nuclear Information System (INIS)

    Although flux transfer events (FTEs) have been observed frequently at high altitudes near the magnetopause their ionospheric signatures remain elusive. Vestiges of FTEs and other magnetopause phenomena have possibly been detected in transient magnetic field perturbations measured on the ground at cusp latitudes. The authors have developed a methodology for use by investigators based on expected, simultaneous measurements of plasma drifts (electric fields), field-aligned currents (magnetic fields) and precipitating particle fluxes. To test and illustrate this methodology they present the results of a search through the available S3-2 data for electric and magnetic field signatures from the mid-day sector displaying irregular structures of scales 100 to 200 km, consistent with ionospheric mapping of FTEs. Out of 36 orbits between December 1975 and April 1976 they found five possible events. An event selected for detailed analysis was observed approximately at 2,219 UT on January 5, 1976 during an equatorward crossing of the northern dayside auroral region at about 1,030 MLT. The qualitative electric and magnetic field fluctuations expected during a satellite encounter with an FTE at ionospheric altitudes are compared with single component measurements for S3-2. Although an encounter with a fast stream in the plasma flow poleward of the cusp cannot be excluded, the data are consistent with expectations for the S3-2 spacecraft having made a near center crossing of an ionospheric footprint of an FTE with a diameter of about 150 km moving eastward along the polar cap boundary with a velocity of 1.3 km/s

  7. Resonant Orbital Dynamics in LEO Region: Space Debris in Focus

    Directory of Open Access Journals (Sweden)

    J. C. Sampaio

    2014-01-01

    Full Text Available The increasing number of objects orbiting the earth justifies the great attention and interest in the observation, spacecraft protection, and collision avoidance. These studies involve different disturbances and resonances in the orbital motions of these objects distributed by the distinct altitudes. In this work, objects in resonant orbital motions are studied in low earth orbits. Using the two-line elements (TLE of the NORAD, resonant angles and resonant periods associated with real motions are described, providing more accurate information to develop an analytical model that describes a certain resonance. The time behaviors of the semimajor axis, eccentricity, and inclination of some space debris are studied. Possible irregular motions are observed by the frequency analysis and by the presence of different resonant angles describing the orbital dynamics of these objects.

  8. High-altitude physiology: lessons from Tibet

    Science.gov (United States)

    Wagner, Peter D.; Simonson, Tatum S.; Wei, Guan; Wagner, Harrieth; Wuren, Tanna; Yan, Ma; Qin, Ga; Ge, Rili

    2013-05-01

    Polycythemia is a universal lowlander response to altitude; healthy Andean high-altitude natives also have elevated [Hb]. While this may enhance O2 transport to tissues, studies have shown that acute isovolumic changes in [Hb] do not affect exercise capacity. Many high-altitude Tibetans have evolved sea-level values of [Hb], providing a natural opportunity to study this issue. In 21 young healthy male Tibetans with [Hb] between 15 and 23 g/dl, we measured VO2MAX and O2 transport capacity at 4200m. VO2MAX was higher when [Hb] was lower (Phigh altitude natives remain polycythemic with larger lungs and higher lung diffusing capacity, a smaller exercising AaPO2, and lower ventilation. The challenges now are (1) to understand the different adaptive pathways used by Andeans and Tibetans, and (2) to determine in Tibetans whether, during evolution, reduced [Hb] appeared first, causing compensatory cardiac and muscle adaptations, or if enhanced cardiac function and muscle O2 transport capacity appeared first, permitting secondary reduction in [Hb]. For (2), further research is necessary to determine the basis of enhanced cardiac function and muscle O2 transport, and identify molecular targets of evolution in heart and muscle. Putative mutations can then be timed and compared to appearance of those affecting [Hb].

  9. Dietary Recommendations for Cyclists during Altitude Training

    Directory of Open Access Journals (Sweden)

    Małgorzata Michalczyk

    2016-06-01

    Full Text Available The concept of altitude or hypoxic training is a common practice in cycling. However, several strategies for training regimens have been proposed, like “live high, train high” (LH-TH, “live high, train low” (LH-TL or “intermittent hypoxic training” (IHT. Each of them combines the effect of acclimatization and different training protocols that require specific nutrition. An appropriate nutrition strategy and adequate hydration can help athletes achieve their fitness and performance goals in this unfriendly environment. In this review, the physiological stress of altitude exposure and training will be discussed, with specific nutrition recommendations for athletes training under such conditions. However, there is little research about the nutrition demands of athletes who train at moderate altitude. Our review considers energetic demands and body mass or body composition changes due to altitude training, including respiratory and urinary water loss under these conditions. Carbohydrate intake recommendations and hydration status are discussed in detail, while iron storage and metabolism is also considered. Last, but not least the risk of increased oxidative stress under hypoxic conditions and antioxidant supplementation suggestions are presented.

  10. Dietary Recommendations for Cyclists during Altitude Training.

    Science.gov (United States)

    Michalczyk, Małgorzata; Czuba, Miłosz; Zydek, Grzegorz; Zając, Adam; Langfort, Józef

    2016-01-01

    The concept of altitude or hypoxic training is a common practice in cycling. However, several strategies for training regimens have been proposed, like "live high, train high" (LH-TH), "live high, train low" (LH-TL) or "intermittent hypoxic training" (IHT). Each of them combines the effect of acclimatization and different training protocols that require specific nutrition. An appropriate nutrition strategy and adequate hydration can help athletes achieve their fitness and performance goals in this unfriendly environment. In this review, the physiological stress of altitude exposure and training will be discussed, with specific nutrition recommendations for athletes training under such conditions. However, there is little research about the nutrition demands of athletes who train at moderate altitude. Our review considers energetic demands and body mass or body composition changes due to altitude training, including respiratory and urinary water loss under these conditions. Carbohydrate intake recommendations and hydration status are discussed in detail, while iron storage and metabolism is also considered. Last, but not least the risk of increased oxidative stress under hypoxic conditions and antioxidant supplementation suggestions are presented. PMID:27322318

  11. Generation and detection of orbital angular momentum via metasurface

    Science.gov (United States)

    Jin, Jinjin; Luo, Jun; Zhang, Xiaohu; Gao, Hui; Li, Xiong; Pu, Mingbo; Gao, Ping; Zhao, Zeyu; Luo, Xiangang

    2016-04-01

    Beams carrying orbital angular momentum possess a significant potential for modern optical technologies ranging from classical and quantum communication to optical manipulation. In this paper, we theoretically design and experimentally demonstrate an ultracompact array of elliptical nanoholes, which could convert the circularly polarized light into the cross-polarized vortex beam. To measure the topological charges of orbital angular momentum in a simple manner, another elliptical nanoholes array is designed to generate reference beam as a reference light. This approach may provide a new way for the generation and detection of orbital angular momentum in a compact device.

  12. Arbitrary optical wavefront shaping via spin-to-orbit coupling

    CERN Document Server

    Larocque, Hugo; Bouchard, Frédéric; Fickler, Robert; Upham, Jeremy; Boyd, Robert W; Karimi, Ebrahim

    2016-01-01

    Converting spin angular momentum to orbital angular momentum has been shown to be a practical and efficient method for generating optical beams carrying orbital angular momentum and possessing a space-varying polarized field. Here, we present novel liquid crystal devices for tailoring the wavefront of optical beams through the Pancharatnam-Berry phase concept. We demonstrate the versatility of these devices by generating an extensive range of optical beams such as beams carrying $\\pm200$ units of orbital angular momentum along with Bessel, Airy and Ince-Gauss beams. We characterize both the phase and the polarization properties of the generated beams, confirming our devices' performance.

  13. Estimation of Orbital Neutron Detector Spatial Resolution by Systematic Shifting of Differential Topographic Masks

    Science.gov (United States)

    McClanahan, T. P.; Mitrofanov, I. G.; Boynton, W. V.; Chin, G.; Livengood, T.; Starr, R. D.; Evans, L. G.; Mazarico, E.; Smith, D. E.

    2012-01-01

    We present a method and preliminary results related to determining the spatial resolution of orbital neutron detectors using epithermal maps and differential topographic masks. Our technique is similar to coded aperture imaging methods for optimizing photonic signals in telescopes [I]. In that approach photon masks with known spatial patterns in a telescope aperature are used to systematically restrict incoming photons which minimizes interference and enhances photon signal to noise. Three orbital neutron detector systems with different stated spatial resolutions are evaluated. The differing spatial resolutions arise due different orbital altitudes and the use of neutron collimation techniques. 1) The uncollimated Lunar Prospector Neutron Spectrometer (LPNS) system has spatial resolution of 45km FWHM from approx. 30km altitude mission phase [2]. The Lunar Rennaissance Orbiter (LRO) Lunar Exploration Neutron Detector (LEND) with two detectors at 50km altitude evaluated here: 2) the collimated 10km FWHM spatial resolution detector CSETN and 3) LEND's collimated Sensor for Epithermal Neutrons (SETN). Thus providing two orbital altitudes to study factors of: uncollimated vs collimated and two average altitudes for their effect on fields-of-view.

  14. Lunar true polar wander inferred from polar hydrogen.

    Science.gov (United States)

    Siegler, M A; Miller, R S; Keane, J T; Laneuville, M; Paige, D A; Matsuyama, I; Lawrence, D J; Crotts, A; Poston, M J

    2016-03-24

    The earliest dynamic and thermal history of the Moon is not well understood. The hydrogen content of deposits near the lunar poles may yield insight into this history, because these deposits (which are probably composed of water ice) survive only if they remain in permanent shadow. If the orientation of the Moon has changed, then the locations of the shadowed regions will also have changed. The polar hydrogen deposits have been mapped by orbiting neutron spectrometers, and their observed spatial distribution does not match the expected distribution of water ice inferred from present-day lunar temperatures. This finding is in contrast to the distribution of volatiles observed in similar thermal environments at Mercury's poles. Here we show that polar hydrogen preserves evidence that the spin axis of the Moon has shifted: the hydrogen deposits are antipodal and displaced equally from each pole along opposite longitudes. From the direction and magnitude of the inferred reorientation, and from analysis of the moments of inertia of the Moon, we hypothesize that this change in the spin axis, known as true polar wander, was caused by a low-density thermal anomaly beneath the Procellarum region. Radiogenic heating within this region resulted in the bulk of lunar mare volcanism and altered the density structure of the Moon, changing its moments of inertia. This resulted in true polar wander consistent with the observed remnant polar hydrogen. This thermal anomaly still exists and, in part, controls the current orientation of the Moon. The Procellarum region was most geologically active early in lunar history, which implies that polar wander initiated billions of years ago and that a large portion of the measured polar hydrogen is ancient, recording early delivery of water to the inner Solar System. Our hypothesis provides an explanation for the antipodal distribution of lunar polar hydrogen, and connects polar volatiles to the geologic and geophysical evolution of the Moon

  15. A multi-satellite study of accelerated ionospheric ion beams above the polar cap

    Directory of Open Access Journals (Sweden)

    R. Maggiolo

    2006-07-01

    Full Text Available This paper presents a study of nearly field-aligned outflowing ion beams observed on the Cluster satellites over the polar cap. Data are taken at geocentric radial distances of the order of 5–9 RE. The distinction is made between ion beams originating from the polar cusp/cleft and beams accelerated almost along the magnetic field line passing by the spacecraft. Polar cusp beams are characterized by nearly field-aligned proton and oxygen ions with an energy ratio EO+ / EH+, of the order of 3 to 4, due to the ion energy repartition inside the source and to the latitudinal extension of the source. Rapid variations in the outflowing ion energy are linked with pulses/modifications of the convection electric field. Cluster data allow one to show that these perturbations of the convection velocity and the associated ion structures propagate at the convection velocity.

    In contrast, polar cap local ion beams are characterized by field-aligned proton and oxygen ions with similar energies. These beams show the typical inverted V structures usually observed in the auroral zone and are associated with a quasi-static converging electric field indicative of a field-aligned electric field. The field-aligned potential drop fits well the ion energy profile. The simultaneous observation of precipitating electrons and upflowing ions of similar energies at the Cluster orbit indicates that the spacecraft are crossing the mid-altitude part of the acceleration region. In the polar cap, the parallel electric field can thus extend to altitudes higher than 5 Earth radii. A detailed analysis of the distribution functions shows that the ions are heated during their parallel acceleration and that energy is exchanged between H+ and O+. Furthermore, intense electrostatic waves are observed simultaneously. These observations could be due to an ion-ion two-stream instability.

  16. Pathology of high altitude pulmonary oedema

    International Nuclear Information System (INIS)

    Objective: To describe autopsy findings in fatal cases of high altitude pulmonary oedema. Study Design: Descriptive study. Place and Duration of Study: The study was carried out between 1999 and 2002 at an army field medical unit in Baltistan, Armed Forces Institute of Pathology, Rawalpindi and Army Medical College, Rawalpindi, Pakistan. Patients and Methods:Autopsies were performed in 17 fatal cases of High Altitude Pulmonary Edema (HAPE) occurring among soldiers serving in Siachen. Results:All cases were males with a mean age of 26.8 years (19-35). The mean altitude at which HAPE occurred was 5192 meters (2895-6492), and the mean duration of stay at these altitudes was 15.3 days (1-30). Eleven individuals had undergone proper acclimatization. The commonest clinical findings were cough (70%), dyspnoea (53%), nausea (47%), headache (41%), vomiting (35%), chest pain (35%) and tightness in chest (24%). Cyanosis and frothy secretions in the nostrils and mouth were present in all but one case. Mean combined weight of lungs was 1470 grams (1070-1810). There was marked congestion of outer and cut surfaces. Interstitial oedema was present in all cases. RBCs and leukocyte infiltrates were seen in 13 and alveolar hyaline membranes in 9 cases. Thrombi were seen in 2 cases. Cerebral oedema was present in 9 cases. Conclusion:HAPE can occur after more than two weeks of stay at high altitudes despite proper acclimatization. Concomitant cerebral oedema is frequently present. Our autopsy findings are consistent with what has been reported previously. (author)

  17. High altitude pulmonary edema among "Amarnath Yatris"

    Directory of Open Access Journals (Sweden)

    Parvaiz A Koul

    2013-01-01

    Full Text Available Background: Annual pilgrimage (Yatra to the cave shrine of Shri Amarnath Ji′ is a holy ritual among the Hindu devotees of Lord Shiva. Located in the Himalayan Mountain Range (altitude 13,000 ft in south Kashmir, the shrine is visited by thousands of devotees and altitude sickness is reportedly common. Materials and Methods: More than 600,000 pilgrims visited the cave shrine in 2011 and 2012 with 239 recorded deaths. Thirty one patients with suspected altitude sickness were referred from medical centers en-route the cave to Sher-i-Kashmir Institute of Medical Sciences, a tertiary-care center in capital Srinagar (5,000 ft. The clinical features and the response to treatment were recorded. Results: Thirty-one patients (all lowlanders, 19 male; age 18-60 years, median 41 had presented with acute onset breathlessness of 1-4 days (median 1.9 d starting within 12-24 h of a rapid ascent; accompanied by cough (68%, headache (8%, dizziness and nausea (65%. Sixteen patients had associated encephalopathy. Clinical features on admission included tachypnea ( n = 31, tachycardia ( n = 23, bilateral chest rales ( n = 29, cyanosis ( n = 22 and grade 2-4 encephalopathy. Hypoxemia was demonstrable in 24 cases and bilateral infiltrates on radiologic imaging in 29. Ten patients had evidence of high-altitude cerebral edema. All patients were managed with oxygen, steroids, nifedipine, sildenafil and other supportive measures including invasive ventilation ( n = 3. Three patients died due to multiorgan dysfunction. Conclusions: Altitude sickness is common among Amaranath Yatris from the plains and appropriate educational strategies should be invoked for prevention and prompt treatment.

  18. Radiation doses at high altitudes and during space flights

    International Nuclear Information System (INIS)

    There are three main sources of the radiation exposure during space flight and at high altitudes: galactic cosmic radiation; solar cosmic radiation; and the radiation of Earth's radiation belts. The first is coming to the Earth's surroundings from the deep cosmos, the second from the Sun. Two radiation belts are centered at thousands of km from the Earth's surface. All the three sources are briefly characterized to give a general idea on their composition, their variations over time and the level of exposure due to them. Radiation doses during space flights will be discussed in the second part of the invited paper, including the possible radiation barriers of long time space exploration missions. Particular attention will be devoted to the quantitative and qualitative characterization of radiation exposure on near-Earth orbits, both theoretical estimation as well as experimental data will be presented. Some remarks on radiation protection philosophy on the board of space vehicles will be also given. The problems concerning the radiation protection of air crew and passengers of subsonic and supersonic air transport will be discussed in the last part of the lecture. General characteristics of on-board radiation fields and their variations with the flight altitude, geomagnetic parameters of a flight and the solar activity will be presented, both based on the theoretical estimation and experimental studies. The questions concerning of aircrew and passengers radiation protection arising after the publication of ICRP 60 recommendations will be also arisen. Activities of different international bodies in this field will be mentioned, the approaches how to manage and check this type of radiation exposure will be presented and discussed. Some examples based on the author's personal experience will be given. (author)

  19. Entanglement of Vector-Polarization States of Photons

    CERN Document Server

    Kong, Ling-Jun; Si, Yu; Liu, Rui; Wang, Zhou-Xiang; Tu, Chenghou; Wang, Hui-Tian

    2015-01-01

    Photons may have homogeneous polarization and may carry quantized orbital angular momentum (OAM). Photon entanglement has been realized in various degrees of freedom such as polarization and OAM. Using a pair of orthogonally polarized states carrying opposite-handedness quantized OAMs could create "quantized" vector polarization states with space-variant polarization structures. It is thus possible to extend the polarization degree of freedom from two dimensional space to indefinite dimensional discrete Hilbert space. We present a class of vector-polarization entangled Bell states, which use the spatial modes of the vector fields with space-variant polarization structure. We propose a scheme of creating the vector-polarization entangled Bell states using a Sagnac interferometer. We also design an analyzer for identifying the vector-polarization entangled Bell states. Such a class of entanglement is important for quantum information science and technology, and fundamental issues of quantum theory, due to its a...

  20. EMIC waves observed by the low-altitude satellite DEMETER during the November 2004 magnetic storm

    Science.gov (United States)

    Píša, D.; Parrot, M.; Santolík, O.; Menietti, J. D.

    2015-07-01

    This paper presents an analysis of ULF (0-20 Hz) waves observed by the low-altitude satellite Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) during the magnetic storm of November 2004. Since these ULF waves are measured by both electric and magnetic antennas, they may be identified as electromagnetic ion cyclotron (EMIC) waves. While EMIC waves have been previously observed in the low-altitude ionosphere, this is the first time that they are observed for such extensive time periods and at such high frequencies. A common feature of these emissions is that their observation region in the low-altitude ionosphere extends continuously from the high-latitude southern trough in one side up to the high-latitude northern trough. The analysis of wave propagation points to the possible source region placed in the inner magnetosphere (L ˜ 2-3). Observed wave frequencies indicate that waves must be generated much farther from the Earth compared to the satellite orbit. Exceptionally high frequencies of about 10 Hz can be explained by the source region placed in the deep inner magnetosphere at L ˜ 2.5. We hypothesize that these waves are generated below the local helium gyrofrequency and propagate over a large range of wave normal angles to reach low altitudes at L ˜ 1.11. In order to investigate this scenario, a future study based on ray tracing simulations will be necessary.

  1. Preliminary Analysis of Delta-V Requirements for a Lunar CubeSat Impactor with Deployment Altitude Variations

    Science.gov (United States)

    Song, Young-Joo; Ho, Jin; Kim, Bang-Yeop

    2015-09-01

    Characteristics of delta-V requirements for deploying an impactor from a mother-ship at different orbital altitudes are analyzed in order to prepare for a future lunar CubeSat impactor mission. A mother-ship is assumed to be orbiting the moon with a circular orbit at a 90 deg inclination and having 50, 100, 150, 200 km altitudes. Critical design parameters that are directly related to the success of the impactor mission are also analyzed including deploy directions, CubeSat flight time, impact velocity, and associated impact angles. Based on derived delta-V requirements, required thruster burn time and fuel mass are analyzed by adapting four different miniaturized commercial onboard thrusters currently developed for CubeSat applications. As a result, CubeSat impact trajectories as well as thruster burn characteristics deployed at different orbital altitudes are found to satisfy the mission objectives. It is concluded that thrust burn time should considered as the more critical design parameter than the required fuel mass when deducing the onboard propulsion system requirements. Results provided through this work will be helpful in further detailed system definition and design activities for future lunar missions with a CubeSat-based payload.

  2. Radiovolumetry of the orbit

    International Nuclear Information System (INIS)

    The authors present a method called ''Radiovolumetry of the orbit'' that permits the evaluation of the orbital volume from anteroposterior skull X-Rays (CALDWELL 300 position). The research was based in the determination of the orbital volume with lead spheres, in 1010 orbits of 505 dry skulls of Anatomy Museums. After the dry skulls was X-rayed six frontal orbital diameters were made, with care to correct the radiographic amplification. PEARSON correlation coeficient test was applied between the mean orbital diameter and the orbital volume. The result was r = 0,8 with P < 0,001. A table was made that permit the determination of the approximate orbital volume from the frontal orbital radiographic diameters. (author)

  3. Why Are High-Altitude Natives So Strong at Altitude? Maximal Oxygen Transport to the Muscle Cell in Altitude Natives.

    Science.gov (United States)

    Lundby, Carsten; Calbet, Jose A L

    2016-01-01

    In hypoxia aerobic exercise performance of high-altitude natives is suggested to be superior to that of lowlanders; i.e., for a given altitude natives are reported to have higher maximal oxygen uptake (VO2max). The likely basis for this is a higher pulmonary diffusion capacity, which in turn ensures higher arterial O2 saturation (SaO2) and therefore also potentially a higher delivery of O2 to the exercising muscles. This review focuses on O2 transport in high-altitude Aymara. We have quantified femoral artery O2 delivery, arterial O2 extraction and calculated leg VO2 in Aymara, and compared their values with that of acclimatizing Danish lowlanders. All subjects were studied at 4100 m. At maximal exercise SaO2 dropped tremendously in the lowlanders, but did not change in the Aymara. Therefore arterial O2 content was also higher in the Aymara. At maximal exercise however, fractional O2 extraction was lower in the Aymara, and the a-vO2 difference was similar in both populations. The lower extraction levels in the Aymara were associated with lower muscle O2 conductance (a measure of muscle diffusion capacity). At any given submaximal exercise intensity, leg VO2 was always of similar magnitude in both groups, but at maximal exercise the lowlanders had higher leg blood flow, and hence also higher maximum leg VO2. With the induction of acute normoxia fractional arterial O2 extraction fell in the highlanders, but remained unchanged in the lowlanders. Hence high-altitude natives seem to be more diffusion limited at the muscle level as compared to lowlanders. In conclusion Aymara preserve very high SaO2 during hypoxic exercise (likely due to a higher lung diffusion capacity), but the effect on VO2max is reduced by a lower ability to extract O2 at the muscle level. PMID:27343089

  4. Correlation effects and orbital magnetism of Co clusters

    CERN Document Server

    Di Marco, L Peters I; Şaşıoğlu, E; Altun, A; Rossen, S; Friedrich, C; Blügel, S; Katsnelson, M I; Kirilyuk, A; Eriksson, O

    2016-01-01

    Recent experiments on isolated Co clusters have shown huge orbital magnetic moments in comparison with their bulk and surface counterparts. These clusters hence provide the unique possibility to study the evolution of the orbital magnetic moment with respect to the cluster size and how competing interactions contribute to the quenching of orbital magnetism. We investigate here different theoretical methods to calculate the spin and orbital moments of Co clusters, and assess the performances of the methods in comparison with experiments. It is shown that density functional theory in conventional local density or generalized gradient approximations, or even with a hybrid functional, severely underestimates the orbital moment. As natural extensions/corrections we considered the orbital polarization correction, the LDA+U approximation as well as the LDA+DMFT method. Our theory shows that of the considered methods, only the LDA+DMFT method provides orbital moments in agreement with experiment, thus emphasizing the...

  5. Quark Wigner distributions and orbital angular momentum

    International Nuclear Information System (INIS)

    We study the Wigner functions of the nucleon which provide multidimensional images of the quark distributions in phase space. These functions can be obtained through a Fourier transform in the transverse space of the generalized transverse-momentum dependent parton distributions. They depend on both the transverse position and the three-momentum of the quark relative to the nucleon, and therefore combine in a single picture all the information contained in the generalized parton distributions and the transverse-momentum dependent parton distributions. We focus the discussion on the distributions of unpolarized/longitudinally polarized quark in an unpolarized/longitudinally polarized nucleon. In this way, we can study the role of the orbital angular momentum of the quark in shaping the nucleon and its correlations with the quark and nucleon polarizations. The quark orbital angular momentum is also calculated from its phase-space average weighted with the Wigner distribution of unpolarized quarks in a longitudinally polarized nucleon. The corresponding results obtained within different light-cone quark models are compared with alternative definitions of the quark orbital angular momentum, as given in terms of generalized parton distributions and transverse-momentum dependent parton distributions.

  6. Polarization in free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

    Papadichev, V.A. [Lebedev Physical Institute, Moscow (Russian Federation)

    1995-12-31

    Polarization of electromagnetic radiation is required very often in numerous scientific and industrial applications: studying of crystals, molecules and intermolecular interaction high-temperature superconductivity, semiconductors and their transitions, polymers and liquid crystals. Using polarized radiation allows to obtain important data (otherwise inaccessible) in astrophysics, meteorology and oceanology. It is promising in chemistry and biology for selective influence on definite parts of molecules in chain synthesis reactions, precise control of various processes at cell and subcell levels, genetic engineering etc. Though polarization methods are well elaborated in optics, they can fail in far-infrared, vacuum-ultraviolet and X-ray regions because of lack of suitable non-absorbing materials and damaging of optical elements at high specific power levels. Therefore, it is of some interest to analyse polarization of untreated FEL radiation obtained with various types of undulators, with and without axial magnetic field. The polarization is studied using solutions for electron orbits in various cases: plane or helical undulator with or without axial magnetic field, two plane undulators, a combination of right- and left-handed helical undulators with equal periods, but different field amplitudes. Some examples of how a desired polarization (elliptical circular or linear) can be obtained or changed quickly, which is necessary in many experiments, are given.

  7. Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Validation with conjunctive Van Allen Probes observations

    Science.gov (United States)

    Soria-Santacruz, M.; Li, W.; Thorne, R. M.; Ma, Q.; Bortnik, J.; Ni, B.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.

    2015-10-01

    Plasmaspheric hiss plays an important role in controlling the overall structure and dynamics of the Earth's radiation belts. The interaction of plasmaspheric hiss with radiation belt electrons is commonly evaluated using diffusion codes, which rely on statistical models of wave observations that may not accurately reproduce the instantaneous global wave distribution or the limited in situ satellite wave measurements. This paper evaluates the performance and limitations of a novel technique capable of inferring wave amplitudes from low-altitude electron flux observations from the Polar Orbiting Environmental Satellites (POES), which provide extensive coverage in shell and magnetic local time (MLT). We found that, within its limitations, this technique could potentially be used to build a dynamic global model of the plasmaspheric hiss wave intensity. The technique is validated by analyzing the conjunctions between the POES spacecraft and the Van Allen Probes from September 2012 to June 2014. The technique performs well for moderate-to-strong hiss activity (≥30 pT) with sufficiently high electron fluxes. The main source of these limitations is the number of counts of energetic electrons measured by the POES spacecraft capable of resonating with hiss waves. For moderate-to-strong hiss events, the results show that the wave amplitudes from the EMFISIS instruments on board the Van Allen Probes are well reproduced by the POES technique, which provides more consistent estimates than the parameterized statistical hiss wave model based on CRRES data.

  8. Alternative Paths for Insertion of Probes in High Inclination Lunar Orbits

    Science.gov (United States)

    de Melo, C. F.; Winter, O. C.

    The dynamics of the circular planar restricted three-body Earth-Moon-particle problem predicts the existence of direct periodic orbits around the Lagrangian equilibrium point L1 From these orbits derive a group of paths that form links between the Earth and the Moon Moreover they are capable of carrying out transfers between terrestrial and lunar orbits of low altitudes When we considered more complex dynamical systems such as the three-dimensional full four-body Sun-Earth-Moon-probe problem which takes into account besides other factors the inclination of the orbit of the Moon these paths leaving terrestrial orbits of low altitudes LEO gain inclination when they penetrate in the sphere of lunar influence allowing the insertion of probes in lunar orbits of high inclinations and low altitudes We studied this property giving emphasis to two types of transfer maneuvers Firstly we investigated direct transfers by inserting probes in lunar orbits with inclinations varying between 29 o and 42 o Next we investigated directed transfers with the application of a Delta V along of the trajectory in order to lead the probe into lunar orbits with inclinations between 0 o and 180 o The results allowed the definition of a group of paths capable of carrying out Earth-moon transfers with flight time between 13 and 16 days with relatively low costs

  9. Reaching High Altitudes on Mars with an Inflatable Hypersonic Drag Balloon (Ballute)

    CERN Document Server

    Griebel, Hannes

    2010-01-01

    The concept of probing the atmosphere of planet Mars by means of a hypersonic drag balloon, a device known as a “ballute”, is a novel approach to planetary science. In this concept, the probe deploys an inflatable drag body out in space and may then enter the atmosphere either once or several times until it slowly descends towards the ground, taking continuous atmospheric and other readings across a large altitude and ground range. Hannes Griebel discusses the theory behind such a mission along with experience gained during its practical implementation, such as mission design, manufacturing, packing and deployment techniques as well as ground and flight tests. The author also studies other ballute applications, specifically emergency low Earth orbit recovery and delivering payloads to high altitude landing sites on Mars.

  10. Pulmonary Function Parameters Changes at Different Altitudes in Healthy Athletes

    Directory of Open Access Journals (Sweden)

    Vahid Ziaee

    2008-06-01

    It could be concluded that changes in some pulmonary ventilatory parameters were proportional to the magnitude of change in altitude during a high-altitude trek. These changes are significant at the beginning of ascending.

  11. The visual control of simulated altitude

    Science.gov (United States)

    Johnson, Walter W.; Bennett, C. Thomas; Tsang, Pamela S.; Phatak, Anil V.

    1987-01-01

    The ability of a subject flying an experimental flight to use the different sources of visual information by looking at the vertical tracking error was investigated using a 3 (altitude) x 3 (texture) x 2 (replication) factorial design. Each subject flew these 18 flights in the same partially counterbalanced order, constructed such that there was one flight at each of the three altitudes, and over each of the three surface textures within each successive set of three flights. The three ground-surface textures used consisted of meridian, latitudinal, and square textures described by Wolpert et al. (1983). The results showed that, in displays where only splay information was available, the subjects tended to confuse lateral motion with vertical.

  12. CT diagnosis of high altitude pulmonary edema

    International Nuclear Information System (INIS)

    Objective: To explore the value of CT diagnosis of high altitude pulmonary edema (HAPE). Methods: The CT findings in 16 patients unfit to high altitude were analyzed. Results: The findings on CT were as follows: (1) The early stage of HAPE showed ground glass opacity, most of which located at the superior segment and posterior basis segment of inferior lobes, with the right lung to occur earlier than that of the left lung. (2) The advanced stage showed shaggy opacity. (3) The late stage lesions developed to posterior and apical segment of the superior lobes, air bronchus sign could be seen on involved segments. (4) Right lung was more serious than left lung. Conclusion: CT was an ideal method to find HAPE. The accuracy of CT diagnosis in HAPE was 100%

  13. HAWC - The High Altitude Water Cherenkov Detector

    Science.gov (United States)

    Tepe, Andreas; HAWC Collaboration

    2012-07-01

    The high altitude water Cherenkov observatory (HAWC) is an instrument for the detection of high energy cosmic gamma-rays. Its predecessor Milagro has successfully proven that the water Cherenkov technology for gamma-ray astronomy is a useful technique. HAWC is currently under construction at Sierra Negra in Mexico at an altitude of 4100 m and will include several improvements compared to Milagro. Two complementary DAQ systems of the HAWC detector allow for the observation of a large fraction of the sky with a very high duty cycle and independent of environmental conditions. HAWC will observe the gamma-ray sky from about 100 GeV up to 100 TeV. Also the cosmic ray flux anisotropy on different angular length scales is object of HAWC science. Because of HAWC's large effective area and field of view, we describe its prospects to observe gamma-ray bursts (GRBs) as an example for transient sources.

  14. POLARBEAR-2: an instrument for CMB polarization measurements

    CERN Document Server

    Inoue, Y; Akiba, Y; Aleman, C; Arnold, K; Baccigalupi, C; Barch, B; Barron, D; Bender, A; Boettger, D; Borrill, J; Chapman, S; Chinone, Y; Cukierman, A; de Haan, T; Dobbs, M A; Ducout, A; Dunner, R; Elleflot, T; Errard, J; Fabbian, G; Feeney, S; Feng, C; Fuller, G; Gilbert, A J; Goeckner-Wald, N; Groh, J; Hall, G; Halverson, N; Hamada, T; Hasegawa, M; Hattori, K; Hazumi, M; Hill, C; Holzapfel, W L; Hori, Y; Howe, L; Irie, F; Jaehnig, G; Jaffe, A; Jeongh, O; Katayama, N; Kaufman, J P; Kazemzadeh, K; Keating, B G; Kermish, Z; Keskital, R; Kisner, T; Kusaka, A; Jeune, M Le; Lee, A T; Leon, D; Linder, E V; Lowry, L; Matsuda, F; Matsumura, T; Miller, N; Mizukami, K; Montgomery, J; Navaroli, M; Nishino, H; Paar, H; Peloton, J; Poletti, D; Puglisi, G; Raum, C R; Rebeiz, G M; Reichardt, C L; Richards, P L; Ross, C; Rotermund, K M; Segaw, Y; Sherwin, B D; Shirley, I; Siritanasak, P; Stebor, N; Suzuki, R Stompor A; Tajima, O; Takada, S; Takatori, S; Teply, G P; Tikhomirol, A; Tomaru, T; Whitehorn, N; Zahn, A; Zahn, O

    2016-01-01

    POLARBEAR-2 (PB-2) is a cosmic microwave background (CMB) polarization experiment that will be located in the Atacama highland in Chile at an altitude of 5200 m. Its science goals are to measure the CMB polarization signals originating from both primordial gravitational waves and weak lensing. PB-2 is designed to measure the tensor to scalar ratio, r, with precision {\\sigma}(r) < 0.01, and the sum of neutrino masses, {\\Sigma}m{\

  15. Predator foraging altitudes reveal the structure of aerial insect communities

    OpenAIRE

    Helms, Jackson A.; Aaron P. Godfrey; Tayna Ames; Bridge, Eli S.

    2016-01-01

    The atmosphere is populated by a diverse array of dispersing insects and their predators. We studied aerial insect communities by tracking the foraging altitudes of an avian insectivore, the Purple Martin (Progne subis). By attaching altitude loggers to nesting Purple Martins and collecting prey delivered to their nestlings, we determined the flight altitudes of ants and other insects. We then tested hypotheses relating ant body size and reproductive ecology to flight altitude. Purple Martins...

  16. The yak genome and adaptation to life at high altitude

    DEFF Research Database (Denmark)

    Qiu, Qiang; Zhang, Guojie; Ma, Tao; Qian, Wubin; Wang, Junyi; Ye, Zhiqiang; Cao, Changchang; Hu, Quanjun; Kim, Jaebum; Larkin, Denis M; Auvil, Loretta; Capitanu, Boris; Ma, Jian; Lewin, Harris A; Qian, Xiaoju; Lang, Yongshan; Zhou, Ran; Wang, Lizhong; Wang, Kun; Xia, Jinquan; Liao, Shengguang; Pan, Shengkai; Lu, Xu; Hou, Haolong; Wang, Yan; Zang, Xuetao; Yin, Ye; Ma, Hui; Zhang, Jian; Wang, Zhaofeng; Zhang, Yingmei; Zhang, Dawei; Yonezawa, Takahiro; Hasegawa, Masami; Zhong, Yang; Liu, Wenbin; Zhang, Yan; Huang, Zhiyong; Zhang, Shengxiang; Long, Ruijun; Yang, Huanming; Lenstra, Johannes A; Cooper, David N; Wu, Yi; Wang, Jun; Shi, Peng; Wang, Jian; Liu, Jianquan

    2012-01-01

    Domestic yaks (Bos grunniens) provide meat and other necessities for Tibetans living at high altitude on the Qinghai-Tibetan Plateau and in adjacent regions. Comparison between yak and the closely related low-altitude cattle (Bos taurus) is informative in studying animal adaptation to high altitude...... important implications for understanding adaptation to high altitude in other animal species and for hypoxia-related diseases in humans....

  17. Is High Altitude Pulmonary Edema Relevant to Hawai‘i?

    OpenAIRE

    Cornell, Seth Lewis

    2014-01-01

    High altitude clinical syndromes have been described in the medical literature but may be under recognized in the state of Hawai‘i. As tourism increases, high altitude injuries may follow given the easy access to high altitude attractions. Visitors and clinicians should be aware of the dangers associated with the rapid ascent to high altitudes in the perceived comfort of a vehicle. This paper will review the basic pathophysiology, prevention, and treatment of the most serious of the high alti...

  18. Pulmonary embolism in young natives of high altitude

    Directory of Open Access Journals (Sweden)

    Sanjay Singhal

    2016-01-01

    Full Text Available Thrombotic events are relatively common in high altitude areas and known to occur in young soldiers working at high altitude without usual risk factors associated with thrombosis at sea-level. However, till now, cases with thrombotic events were reported only in lowlanders staying at high altitude. These two cases of pulmonary embolism demonstrate that thrombotic events can occur in highlanders after a prolonged stay at the extreme altitude.

  19. Pulse oximetry reference values at high altitude.

    OpenAIRE

    Lozano, J.M.; Duque, O R; Buitrago, T; Behaine, S

    1992-01-01

    Pulse oximetry is becoming popular for measuring oxygen saturation of haemoglobin in paediatric patients. There are no reference values for children living at high altitudes, and the aim of this study was to determine the values of oxygen saturation of haemoglobin in healthy children in Bogota (2640 m above sea level). The saturation was determined in 189 children aged 5 days to 24 months with a Nellcor N10 oximeter. Mean values and 95% confidence intervals (CI) were calculated. Analysis of v...

  20. Cardiovascular Response to High Altitude Hypoxia

    OpenAIRE

    Manchanda, S C

    1984-01-01

    Normal and abnormal cardiovascular response to high altitude (HA) hypoxia were studied in 98 healthy subjects and in 15 patients with HA pulmonary oedema (HAPO) and acute mountain sickness (AMS) at an altitudeof 3,658 m. The healthy sea level (SL) residents showed marked blood volume changes during the first week with pulmonary hypotension and depression of left ventricular (LV) performance and physical work capacity (PWC). The HA natives, however, had better LV performance and PWC indicating...

  1. Magion-4 High-Altitude Cusp Study

    Czech Academy of Sciences Publication Activity Database

    Merka, J.; Šafránková, J.; Němeček, Z.; Šimůnek, Jiří

    2005-01-01

    Roč. 26, č. 1-3 (2005), s. 57-69. ISSN 0169-3298 R&D Projects: GA ČR(CZ) GA205/02/0947 Institutional research plan: CEZ:AV0Z30420517 Keywords : cusp-like plasma * dipole tilt angle * high - altitude cusp * magnetopause * magnetopause * reconnection Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.975, year: 2005

  2. Is high-altitude mountaineering Russian roulette?

    OpenAIRE

    Cheng Edward K.

    2013-01-01

    Whether the nature of the risks associated with climbing high-altitude (8000 m) peaks is in some sense “controllable” is a longstanding debate in the mountaineering community. Well-known mountaineers David Roberts and Ed Viesturs explore this issue in their recent memoirs. Roberts views the primary risks as “objective” or uncontrollable, whereas Viesturs maintains that experience and attention to safety can make a significant difference. This study sheds light on the Roberts-Viesturs debate u...

  3. Phase-space rotations and orbital Stokes parameters.

    Science.gov (United States)

    Alieva, Tatiana; Bastiaans, Martin J

    2009-02-15

    We introduce the orbital Stokes parameters as a linear combination of a beam's second-order moments. Similar to the ones describing the field polarization and associated with beam energy and its spin angular momentum, the orbital Stokes parameters are related to the total beam width and its orbital angular momentum. We derive the transformation laws for these parameters during beam propagation through first-order optical systems associated with phase-space rotations. The values of the orbital Stokes parameters for Gaussian modes and arbitrary fields expressed as their linear superposition are obtained. PMID:19373324

  4. Time-domain inspiral templates for spinning compact binaries in quasi-circular orbits described by their orbital angular momenta

    International Nuclear Information System (INIS)

    We present a prescription to compute the time-domain gravitational wave (GW) polarization states associated with spinning compact binaries inspiraling along quasi-circular orbits. We invoke the orbital angular momentum L rather than its Newtonian counterpart LN to describe the binary orbits while the two spin vectors are freely specified in an inertial frame associated with the initial direction of the total angular momentum. We show that the use of L to describe the orbits leads to additional 1.5PN order amplitude contributions to the two GW polarization states compared to the LN-based approach and discuss few implications of our approach. Furthermore, we provide a plausible prescription for GW phasing based on certain theoretical considerations and which may be treated as the natural circular limit to GW phasing for spinning compact binaries in inspiraling eccentric orbits (Gopakumar A and Schäfer G 2011 Phys. Rev. D 84 124007). (paper)

  5. The Italian Spacegate: Study and innovative approaches to future generation transportation based on High Altitude Flight

    Science.gov (United States)

    Santoro, Francesco; Bellomo, Alessandro; Bolle, Andrea; Vittori, Roberto

    2014-08-01

    This paper summarizes the results of the pre-feasibility studies carried out in 2012 on the concept of sub orbital and hypersonic, high altitude flight in support of future generation transportation. Currently, while the High Altitude Flight is mostly instrumental to touristic purposes and emphasizes the so called Spaceports as futuristic, customers-luring airports featured with all the support services, the “Spacegate” concept deals with scheduled traveling in the upper part of the atmosphere between two points over the Earth surface, with significant reduction of the transfer time. The first part of the paper provides a theoretical approach to the matter, by proposing an “operational” mapping of the atmosphere as well as of the different kinds of flight occurring at High Altitude. The second part of the paper addresses the problem of the limited human capability of maintaining an active control of the vehicle during the re-entry phase and introduces the “Spacegate” concept as the conical portion of the atmosphere above the landing site, whose surface delimits the spiral-descending trajectories that the pilot can travel for a safe re-entry. This paper further outlines the results of the preliminary definition of top level operational requirements and derived architecture functional modules in support to the “Spacegate” implementation. Special attention was given to the favorable geographic and climatic conditions of Italy that make this Country suitable enough for future experimental sub orbital flights and related operations. An initial analysis was performed on the regulatory backbone that has to be built to properly operate High Altitude Flight vehicles in Italy according to the concept of an Italian “Spacegate”. A Preliminary Master Plan/Road Map for the “Spacegate” has been laid out, with special emphasis to selected near term activities and support infrastructures necessary to be carried out to better refine the study in preparation

  6. The High Altitude Water Cherenkov Observatory

    Science.gov (United States)

    Mostafa, Miguel; HAWC Collaboration

    2016-03-01

    The High Altitude Water Cherenkov (HAWC) Observatory is a continuously operated, wide field of view experiment comprised of an array of 300 water Cherenkov detectors (WCDs) to study transient and steady emission of TeV gamma and cosmic rays. Each 200000 l WCD is instrumented with 4 PMTs providing charge and timing information. The array covers ~22000 m2 at an altitude of 4100 m a.s.l. inside the Pico de Orizaba national park in Mexico. The high altitude, large active area, and optical isolation of the PMTs allows us to reliably estimate the energy and determine the arrival direction of gamma and cosmic rays with significant sensitivity over energies from several hundred GeV to a hundred TeV. Continuously observing 2 / 3 of the sky every 24 h, HAWC plays a significant role as a survey instrument for multi-wavelength studies. The performance of HAWC makes possible the detection of both transient and steady emissions, the study of diffuse emission and the measurement of the spectra of gamma-ray sources at TeV energies. HAWC is also sensitive to the emission from GRBs above 100 GeV. I will highlight the results from the first year of operation of the full HAWC array, and describe the ongoing site work to expand the array by a factor of 4 to explore the high energy range.

  7. Lunar Orbiter Photo Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Lunar Orbiter Photo Gallery is an extensive collection of over 2,600 high- and moderate-resolution photographs produced by all five of the Lunar Orbiter...

  8. ASC Champ Orbit Model

    DEFF Research Database (Denmark)

    Riis, Troels; Jørgensen, John Leif

    1999-01-01

    This documents describes a test of the implementation of the ASC orbit model for the Champ satellite.......This documents describes a test of the implementation of the ASC orbit model for the Champ satellite....

  9. The effect of altitude hypoxia on glucose homeostasis in men

    DEFF Research Database (Denmark)

    Larsen, J J; Hansen, J M; Olsen, Niels Vidiendal;

    1997-01-01

    1. Exposure to altitude hypoxia elicits changes in glucose homeostasis with increases in glucose and insulin concentrations within the first few days at altitude. Both increased and unchanged hepatic glucose production (HGP) have previously been reported in response to acute altitude hypoxia...

  10. Nutritional Aspects of High Altitude and Snow Bound Areas

    OpenAIRE

    K. Sridharan; R. M. Rai

    1984-01-01

    The precise nutritional requirement of humans at high altitude area is not well defined. Further there are many conflicting reports on the effects of hypoxia on digestion, absorption and utilization of food at high altitude. In this review the nutritional requirements at high altitude and the effects of hypoxia on humans in relation to nutrition have been discussed.

  11. Nutritional Aspects of High Altitude and Snow Bound Areas

    Directory of Open Access Journals (Sweden)

    K. Sridharan

    1984-10-01

    Full Text Available The precise nutritional requirement of humans at high altitude area is not well defined. Further there are many conflicting reports on the effects of hypoxia on digestion, absorption and utilization of food at high altitude. In this review the nutritional requirements at high altitude and the effects of hypoxia on humans in relation to nutrition have been discussed.

  12. Drift-parallax determination of the altitude of traveling ionospheric disturbances observed with the Los Alamos radio-beacon interferometer

    International Nuclear Information System (INIS)

    From 1993 to 1997, the Los Alamos very long baseline interferometer was routinely employed to detect traveling ionospheric disturbances (TID) and inner plasmaspheric irregularities by measuring the change in the electrical phase of several satellite beacon signals that backlit the inner plasmasphere and ionosphere from geosynchronous orbit. The fortuitous placement of two satellite beacons nearly in the Los Alamos geographic meridian, in late 1995, permits us to infer the nominal altitude of each TID event by employing a novel parallax ranging technique. In the context of this paper, the nominal altitude of a TID refers to the altitude at which the slant-path averaged, amplitude-weighted phase perturbation existed along the lines of sight from the interferometer to the satellite. In this paper, we outline the method and present validation results. copyright 1998 American Geophysical Union

  13. Orbital Tumors and Pseudotumors

    OpenAIRE

    Talan-Hranilović, Jasna; Tomas, Davor

    2004-01-01

    Twenty-four orbital tumors and 4 pseudotumors diagnosed in biopsy material among 596 ophthalmic tumors examined during the 1998-2003 period are presented according to patient age and sex, tumor histology and immunohistochemistry. The most common orbital tumors were lipomas, meningiomas and lymphomas, with a peak incidence in the seventh decade of life. Most orbital tumors of childhood are distinguished from those occurring in adults. Most pediatric orbital tumors are benign (developmental cys...

  14. Endoscopic orbital decompression

    OpenAIRE

    Balasubramanian Thiagarajan

    2014-01-01

    Orbital decompression surgery has been indicated in patients with compressive optic neuropathy, severe corneal exposure, cosmetic deformity due to proptosis. Traditional orbital decompression approaches were fraught with complications. With the advent of nasal endoscopes decompression is being carried out transnasally under endoscopic guidance. The entire medial wall of orbit can be taken down transnasally using nasal endoscope, and the inferior wall of orbit can be removed using the...

  15. Comparison of interball-2 spacecraft potential from IESP and KM-7 experiments in high-latitude regions of the magnetosphere at altitudes of 2-3 RE

    Science.gov (United States)

    Smirnova, N.; Afonin, V.; Smilauer, Ja.; Stanev, G.

    Measurements of Interball-2 spacecraft potential by two instruments, IESP and KM-7, are reviewed and simultaneous measurements are compared. Unacceptable discrepancy between results of spacecraft potential measurements, including opposite signs, was found. Actually, both experiments are methodically identical: they used the same type of sensor - spherical Langmuir probes operating in the ``floating'' mode, and they have measured the same parameter - the voltage difference between the probe and the satellite structure. The IESP instrument measured one value of this parameter at fixed bias current to the probe. The KM-7 measured the whole current-voltage characteristic (the probe current as a function of the probe potential), which consists of 11 IESP-type measurements at different values of bias current. The difference lies only in the way of technical implementation, as the probes were operating in different ambient conditions. The IESP probes were mounted at the ends of long booms and thus were affected by the solar UV emission, while the KM-7 probe was rather well protected against UV emission by proper mounting and screening the head of the sensor from both direct UV emission and those reflected from spacecraft elements. The comparison of two data sets and variations along the orbit has shown, that KM-7 correctly measures the spacecraft potential. In high-latitude inner magnetosphere (in auroral region and polar cap) at altitudes 2-3 RE the spacecraft potential was predominantly negative down to -10 V, increasing up to about +5 V in some locations at rather extended parts of the satellite orbit. Reasonably good agreement between two experiments was obtained only at spacecraft potential wrong and misleading results.

  16. Aerodynamic Stability of Satellites in Elliptic Low Earth Orbits

    CERN Document Server

    Bailey, Matthew; Mancas, Stefan C; Udrea, Bogdan; Umeadi, Uchenna

    2013-01-01

    Topical observations of the thermosphere at altitudes below $200 \\, km$ are of great benefit in advancing the understanding of the global distribution of mass, composition, and dynamical responses to geomagnetic forcing, and momentum transfer via waves. The perceived risks associated with such low altitude and short duration orbits has prohibited the launch of Discovery-class missions. Miniaturization of instruments such as mass spectrometers and advances in the nano-satellite technology, associated with relatively low cost of nano-satellite manufacturing and operation, open an avenue for performing low altitude missions. The time dependent coefficients of a second order non-homogeneous ODE which describes the motion have a double periodic shape. Hence, they will be approximated using Jacobi elliptic functions. Through a change of variables the original ODE will be converted into Hill's ODE for stability analysis using Floquet theory. We are interested in how changes in the coefficients of the ODE affect the ...

  17. Eye and orbital cavity

    International Nuclear Information System (INIS)

    Radioanatomy of eyes and orbit is described. Diseases of the orbit (developmental anomalies, inflammatory diseases, lacrimal apparatus deseases, toxoplasmosis, tumors and cysts et al.), methods of foreign body localization in the eye are considered. Roentgenograms of the orbit and calculation table for foreign body localization in spherical eyes of dissimilar diameter are presented

  18. On the Accuracy of Stratospheric Meteorological Reanalyses Using Wind Measurements at High Altitude in the Stratosphere

    Science.gov (United States)

    Huret, N.; Duruisseau, F.; Andral, A.

    2015-09-01

    This study is motivated by the improvement of the knowledge of stratospheric dynamics and the evaluation of the ability of models to represent wind variability in the stratosphere. We deduce from the Zero Pressure Balloons trajectories, operated by CNES during the last decade, zonal and meridional wind to provide a unique database in the altitude range [25-40] km. The collected data are associated with ZBP flights launch during winter and summer in polar region above the Esrange (Sweden) launch base and in equatorial region above the Teresina (Brazil) during easterly and westerly Quasibiennal Oscillation phase. We performed systematic comparisons between wind measurements and ERA—interim reanalysis from ECMWF (European Centre for Medium-Range Weather Forecasts) and present the vertical profile of biases for both wind component in winter at high latitude. The biases and the standard deviation obtained increase with altitude.

  19. Analytical investigation of a nanosatellite panel surface temperatures for different altitudes and panel combinations

    International Nuclear Information System (INIS)

    The thermal control of future nanosatellite will be challenging due to dedicated panel surface area for radiation. The thermal control concept is to keep the payload within allowable temperature ranges. In order to predict the temperature for a nanosatellite in orbit, a basic thermal model of the nanosatellite was designed and analyzed. A thermal control system of the nanosatellite at an altitude 600 km with an inclination of 98° is presented. A thermal analysis of the nanosatellite was also performed with different altitudes from 500 km to 2000 km. A thermal control analysis of CubeSat's passive thermal control system was conducted. A temperature distribution of the solutions was computed. All electronic equipment and structural parts were within allowable temperatures, except the batteries. The batteries were out of their allowed range of temperatures in the cold case condition. The results of the study showed that the panel surface temperature results for different altitudes and panel combination are highly sensitive by the chosen surface coating of the nanosatellite. - Highlights: • Dimensions of 10 cm × 10 cm × 10 cm and a weight of 1 kg of CubeSat were used. • Initial and detailed thermal analysis were performed. • Initial thermal analysis with different altitude from 500 km to 2000 km was performed. • The surface temperatures of nanosatellite were not affected by the altitude of the nanosatellite. • All electronic equipment and structural part were within allowable temperature range except the batteries

  20. Electromagnetic effects on the orbital motion of a charged spacecraft

    Science.gov (United States)

    Abdel-Aziz, Yehia Ahmed; Khalil, Khalil Ibrahim

    2014-05-01

    This paper deals with the effects of electromagnetic forces on the orbital motion of a spacecraft. The electrostatic charge which a spacecraft generates on its surface in the Earth's magnetic field will be subject to a perturbative Lorentz force. A model incorporating all Lorentz forces as a function of orbital elements has been developed on the basis of magnetic and electric fields. This Lorentz force can be used to modify or perturb the spacecraft's orbits. Lagrange's planetary equations in the Gauss variational form are derived using the Lorentz force as a perturbation to a Keplerian orbit. Our approach incorporates orbital inclination and the true anomaly. The numerical results of Lagrange's planetary equations for some operational satellites show that the perturbation in the orbital elements of the spacecraft is a second order perturbation for a certain value of charge. The effect of the Lorentz force due to its magnetic component is three times that of the Lorentz force due to its electric component. In addition, the numerical results confirm that the strong effects are due to the Lorentz force in a polar orbit, which is consistent with realistic physical phenomena that occur in polar orbits. The results confirm that the magnitude of the Lorentz force depends on the amount of charge. This means that we can use artificial charging to create a force to control the attitude and orbital motion of a spacecraft.

  1. Electromagnetic effects on the orbital motion of a charged spacecraft

    International Nuclear Information System (INIS)

    This paper deals with the effects of electromagnetic forces on the orbital motion of a spacecraft. The electrostatic charge which a spacecraft generates on its surface in the Earth's magnetic field will be subject to a perturbative Lorentz force. A model incorporating all Lorentz forces as a function of orbital elements has been developed on the basis of magnetic and electric fields. This Lorentz force can be used to modify or perturb the spacecraft's orbits. Lagrange's planetary equations in the Gauss variational form are derived using the Lorentz force as a perturbation to a Keplerian orbit. Our approach incorporates orbital inclination and the true anomaly. The numerical results of Lagrange's planetary equations for some operational satellites show that the perturbation in the orbital elements of the spacecraft is a second order perturbation for a certain value of charge. The effect of the Lorentz force due to its magnetic component is three times that of the Lorentz force due to its electric component. In addition, the numerical results confirm that the strong effects are due to the Lorentz force in a polar orbit, which is consistent with realistic physical phenomena that occur in polar orbits. The results confirm that the magnitude of the Lorentz force depends on the amount of charge. This means that we can use artificial charging to create a force to control the attitude and orbital motion of a spacecraft

  2. Mercury's Seasonal Sodium Exosphere: MESSENGER Orbital Observations

    Science.gov (United States)

    Cassidy, Timothy A.; Merkel, Aimee W.; Burger, Matthew H.; Killen, Rosemary M.; McClintock, William E.; Vervack, Ronald J., Jr.; Sarantos, Menelaos

    2014-01-01

    The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Ultraviolet and Visible Spectrometer (UVVS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft now orbiting Mercury provides the first close-up look at the planet's sodium exosphere. UVVS has observed the exosphere from orbit almost daily for over 10 Mercury years. In this paper we describe and analyze a subset of these data: altitude profiles taken above the low-latitude dayside and south pole. The observations show spatial and temporal variations, but there are no obvious year-to-year variations in most of the observations. We do not see the episodic variability reported by some ground-based observers. We used these altitude profiles to make estimates of sodium density and temperature. The bulk of the exosphere, at about 1200 K, is much warmer than Mercury's surface. This value is consistent with some ground-based measurements and suggests that photon-stimulated desorption is the primary ejection process. We also observe a tenuous energetic component but do not see evidence of the predicted thermalized (or partially thermalized) sodium near Mercury's surface temperature. Overall we do not see the variable mixture of temperatures predicted by most Monte Carlo models of the exosphere.

  3. Orbit Determination of Chang'e-3 and Positioning of the Lander and the Rover

    Science.gov (United States)

    Huang, Y.; Chang, S.; Li, P.; Hu, X.

    2014-12-01

    The Chang'E-3 (CE-3) lunar probe of China was launched on 2 December 2013. After about 112 h of flight, it was captured by the Moon on 6 December, and entered a polar, near circular lunar orbit with an altitude of approximately 100 km. The probe's flight on 100 km*100 km and 100 km*15 km orbit lasted about 4 days respectively, then the probe soft landed on the east of Sinus Iridum area at 13:11 UTC on 14 December successfully. Results on precision orbit determination and positioning of the lander and the rover are presented here. We describe the data, modeling and methods used to achieve position knowledge. In addition to the radiometric X-band range and Doppler tracking data, Delta Differential One-way Ranging (ΔDOR) data are also used in the calculation, which shows that they can improve the accuracy of the orbit reconstruction. Total position overlap differences are about 20 m and 30 m for the 100 km*100 km and 100 km*15 km lunar orbit respectively, increased by ~50 % with respect to CE-2. A kinematic statistical method is applied to determine the position of the lander and relative position of the rover with respect to the lander. The location of the lander is computed as: 44.1216º N, 19.5124º W and -2632.0 m in the lunar Mean Axes coordinate system. The position difference of the lander is better than 50 m compared to the result of the LRO photograph. From 15 to 21 December, the rover walked around the lander, and took photos of each other at the parking point A, B, C, D, E (max distance from the lander is about 25 m). The delta VLBI phase delay data are used to compute the relative position of the rover at the parking points, and the accuracy of the relative position can reach to 1-2 m comparing with the results of visual method.

  4. Nickel hydrogen low earth orbit life testing

    Science.gov (United States)

    Badcock, Charles C.; Haag, R. L.

    1988-02-01

    A program to demonstrate the long-term reliability of nickel hydrogen (NiH2) cells in low earth orbit (LEO) and support use in mid-altitude orbit (MAO) has been initiated. Both 3.5 and 4.5 in. diameter NiH2 cells are included in the test plan. Cells from all U.S. vendors are to be tested. The tests will be performed at -5 and 10 C at 40 and 60 percent depth of discharge (DOD) for LEO orbit and 10 C and 80 percent DOD for MAO orbit simulations. The goals of the testing are 20,000 cycles at 60 percent DOD and 30,000 cycles at 40 percent DOD. Cells are presently undergoing acceptance and characterization testing at Naval Weapons Support Center (NWSC), Crane, Indiana. Funding has been provided by the Air Force Space Technology Center (AFSTC) and two AF System Program Offices (SPO's) to initiate the testing, but additional funding must be acquired to complete the purchase of cells and to assure completion of the testing.

  5. Orbit Software Suite

    Science.gov (United States)

    Osgood, Cathy; Williams, Kevin; Gentry, Philip; Brownfield, Dana; Hallstrom, John; Stuit, Tim

    2012-01-01

    Orbit Software Suite is used to support a variety of NASA/DM (Dependable Multiprocessor) mission planning and analysis activities on the IPS (Intrusion Prevention System) platform. The suite of Orbit software tools (Orbit Design and Orbit Dynamics) resides on IPS/Linux workstations, and is used to perform mission design and analysis tasks corresponding to trajectory/ launch window, rendezvous, and proximity operations flight segments. A list of tools in Orbit Software Suite represents tool versions established during/after the Equipment Rehost-3 Project.

  6. Lunar Reconnaissance Orbiter Camera (LROC) instrument overview

    Science.gov (United States)

    Robinson, M.S.; Brylow, S.M.; Tschimmel, M.; Humm, D.; Lawrence, S.J.; Thomas, P.C.; Denevi, B.W.; Bowman-Cisneros, E.; Zerr, J.; Ravine, M.A.; Caplinger, M.A.; Ghaemi, F.T.; Schaffner, J.A.; Malin, M.C.; Mahanti, P.; Bartels, A.; Anderson, J.; Tran, T.N.; Eliason, E.M.; McEwen, A.S.; Turtle, E.; Jolliff, B.L.; Hiesinger, H.

    2010-01-01

    The Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) and Narrow Angle Cameras (NACs) are on the NASA Lunar Reconnaissance Orbiter (LRO). The WAC is a 7-color push-frame camera (100 and 400 m/pixel visible and UV, respectively), while the two NACs are monochrome narrow-angle linescan imagers (0.5 m/pixel). The primary mission of LRO is to obtain measurements of the Moon that will enable future lunar human exploration. The overarching goals of the LROC investigation include landing site identification and certification, mapping of permanently polar shadowed and sunlit regions, meter-scale mapping of polar regions, global multispectral imaging, a global morphology base map, characterization of regolith properties, and determination of current impact hazards.

  7. Optical coronal polarization and solar dust ring

    International Nuclear Information System (INIS)

    Observations of the outer solar corona on the Java island were carried out on June 11, 1983, at a 30-km altitude using a B-15 balloon. At 5325, 5965, 7200, and 8015 A, data on polarizations in a field of 5 deg x 5 deg centered nearly on the sun were obtained. Our contour maps of polarization are the first of the two-dimensional polarization distribution covering wide area. An excess of polarization at the four wavelengths was found in the ecliptic plane and at the location of a coronal streamer. High polarization at the coronal streamer is caused mainly by coronal electrons, but dust grains in the region out of the ecliptic plane contribute also in a few percent to the high polarization degree in this streamer. It is confirmed by additional data that there is a peak in the polarization excess in the ecliptic between 4(R solar) and 5(R solar) as already reported by Isobe et al. (1985; AAA 40.074.053). This excess is considered to be due to an enhanced distribution of dust in a ring or a thick wide band around the sun. (author)

  8. Application of circular polarized synchrotron radiation

    International Nuclear Information System (INIS)

    The idea of using the polarizing property of light for physical experiment by controlling it variously has been known from old time, and the Faraday effect and the research by polarizing microscopy are its examples. The light emitted from the electron orbit of an accelerator has the different polarizing characteristics from those of the light of a laboratory light source, and as far as observing it within the electron orbit plane, it becomes linearly polarized light. By utilizing this property well, research is carried out at present in synchrotron experimental facilities. Recently, the technology related to the insert type light cources using permanent magnets has advanced remarkably, and circular polarized light has become to be producible. If the light like this can be obtained with the energy not only in far ultraviolet region but also to x-ray region at high luminance, new possibility should open. At the stage that the design of an insert type light source was finished, and its manufacture was started, the research on the method of evaluating the degree of circular polarization and the research on the utilization of circular polarized synchrotron radiation are earnestly carried out. In this report, the results of researches presented at the study meeting are summarized. Moreover, the design and manufacture of the beam lines for exclusive use will be carried out. (Kako, I.)

  9. Improved Maneuver Reconstructions for the GRAIL Orbiters

    Science.gov (United States)

    Keck, Mason; You, Tung-Han; Antreasian, Peter

    2012-01-01

    Maneuver reconstructions for the Gravity Recovery and Interior Laboratory (GRAIL) A and B lunar orbiters were improved through updates to the orbit determination filter and dynamic models. Consistent reconstructions of the 27 GRAIL A and B maneuvers from the Trans-Lunar Cruise phase in the fall of 2011 through the Transition to Science Formation phase in February 2012 were performed. Standard methods of orbit determination were applied incorporating the latest dynamic models and filter strategies developed by the GRAIL Navigation and Science Teams, including a high resolution, 420 x 420 degree and order lunar spherical harmonic gravity field model. For Trans-Lunar Cruise for GRAIL-A (TLC-A), all maneuvers executed with delta V errors below 5.50 +/- 0.50 mm/s and pointing errors below 0.25 degrees. GRAIL-A lunar orbit maneuvers had delta V errors below 30.0 mm/s and pointing errors below 0.51 degrees. For TLC-B, all maneuvers executed with delta V errors below 8.60 +/- 1.41 mm/s and pointing errors below 0.300 degrees. GRAIL-B maneuvers in lunar orbit executed with maximum delta V errors of 25.0 mm/s and pointing error of 0.43 degrees. These maneuver reconstructions will enable the GRAIL Navigation Team to better characterize the main engine performance of each spacecraft. This will help the Navigation Team to navigate low (greater than 8 km) altitude orbits during the extended mission phase in the fall of 2012.

  10. Orbital fractures: a review

    Directory of Open Access Journals (Sweden)

    Jeffrey M Joseph

    2011-01-01

    Full Text Available Jeffrey M Joseph, Ioannis P GlavasDivision of Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, School of Medicine, New York University, New York, NY, USA; Manhattan Eye, Ear, and Throat Hospital, New York, NY, USAAbstract: This review of orbital fractures has three goals: 1 to understand the clinically relevant orbital anatomy with regard to periorbital trauma and orbital fractures, 2 to explain how to assess and examine a patient after periorbital trauma, and 3 to understand the medical and surgical management of orbital fractures. The article aims to summarize the evaluation and management of commonly encountered orbital fractures from the ophthalmologic perspective and to provide an overview for all practicing ophthalmologists and ophthalmologists in training.Keywords: orbit, trauma, fracture, orbital floor, medial wall, zygomatic, zygomatic complex, zmc fracture, zygomaticomaxillary complex fractures 

  11. Solar regenerative fuel cell system for high altitude airships

    International Nuclear Information System (INIS)

    'Full text': A closed-loop regenerative fuel cell (RFC) system that serves as an energy storage device for space activities is studied through dynamic simulations. The unique nature of the closed-loop RFC makes it an ideal power system for key applications in homeland defense and earth observatory systems such as high altitude aircrafts /airships, unmanned aerial vehicles, and in planetary exploration for flyer or for surface power. The RFC considered using the photovoltaic cells to produce electric power during the day, part of which is used to produce hydrogen and oxygen through electrolysis. The stored hydrogen and oxygen is used through a fuel cell to produce electric power during night hours. A MATLAB/SIMULINK model was developed for the components of the RFC that include a fuel cell, electrolyzer, photovoltaic solar array, power bus, humidifiers, compressor/motor assembly, expander, pumps, phase separators, storage tanks for hydrogen, oxygen and water, control valves and piping, electric grid system and controls. A proton exchange membrane (PEM) fuel cell and PEM electrolyzer were modeled in detail that included the mass momentum, energy, chemical reaction rates at cathode and anode. The PEM fuel cell voltage was modeled accounting cell activation and ohmic polarizations. A modular approach was used to develop models for each component. Component models were based on fundamental physics to the extent practical. Steady state and dynamic response of the RFC for different operational conditions including start-up, shut down, load changes and (accidental) transients was studied. (author)

  12. Dose-response of altitude training: how much altitude is enough?

    Science.gov (United States)

    Levine, Benjamin D; Stray-Gundersen, James

    2006-01-01

    Altitude training continues to be a key adjunctive aid for the training of competitive athletes throughout the world. Over the past decade, evidence has accumulated from many groups of investigators that the "living high--training low" approach to altitude training provides the most robust and reliable performance enhancements. The success of this strategy depends on two key features: 1) living high enough, for enough hours per day, for a long enough period of time, to initiate and sustain an erythropoietic effect of high altitude; and 2) training low enough to allow maximal quality of high intensity workouts, requiring high rates of sustained oxidative flux. Because of the relatively limited access to environments where such a strategy can be practically applied, numerous devices have been developed to "bring the mountain to the athlete," which has raised the key issue of the appropriate "dose" of altitude required to stimulate an acclimatization response and performance enhancement. These include devices using molecular sieve technology to provide a normobaric hypoxic living or sleeping environment, approaches using very high altitudes (5,500m) for shorter periods of time during the day, and "intermittent hypoxic training" involving breathing very hypoxic gas mixtures for alternating 5 minutes periods over the course of 60-90 minutes. Unfortunately, objective testing of the strategies employing short term (less than 4 hours) normobaric or hypobaric hypoxia has failed to demonstrate an advantage of these techniques. Moreover individual variability of the response to even the best of living high--training low strategies has been great, and the mechanisms behind this variability remain obscure. Future research efforts will need to focus on defining the optimal dosing strategy for these devices, and determining the underlying mechanisms of the individual variability so as to enable the individualized "prescription" of altitude exposure to optimize the performance of

  13. Earth orbiting technologies for understanding global change

    Science.gov (United States)

    Harris, Leonard A.; Johnston, Gordon I.; Hudson, Wayne R.; Couch, Lana M.

    1989-01-01

    This paper considers the technology requirements needed to support the Mission to Planet Earth concept, which will consist of several sun synchronous polar platforms; a series of low-earth orbit equatorial missions, such as Space Shuttle payloads, Space-Station-attached payloads, and the Explorer-class Earth Probes; and five geostationary platforms. In particular, the technology requirements in the areas of space-based observation, data/information, and spacecraft operation are examined.

  14. Wigner distributions and quark orbital angular momentum

    OpenAIRE

    Cedric LorceOrsay, IPN and Orsay, LPT; Barbara Pasquini(Pavia U. and INFN, Pavia)

    2015-01-01

    We discuss the quark phase-space or Wigner distributions of the nucleon which combine in a single picture all the information contained in the generalized parton distributions and the transverse-momentum dependent parton distributions. In particular, we present results for the distribution of unpolarized quarks in a longitudinally polarized nucleon obtained in a light-front constituent quark model. We show how the quark orbital angular momentum can be extracted from the Wigner distributions a...

  15. Effect of Polarization in (e, 2e) Ionization of Argon

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-Ying; ZHOU Ya-Jun

    2004-01-01

    @@ The triple differential cross section of the Ar 2p orbital in a highly asymmetric geometry is calculated by using a modified distorted wave Born approximation method. A short-range polarization potential via density-functional theory is included in our calculations. It is shown that polarization potential is particularly important for calculations of the triple differential cross section.

  16. The potential for ozone depletion in the Arctic polar stratosphere

    Science.gov (United States)

    Brune, W. H.; Anderson, J. G.; Toohey, D. W.; Fahey, D. W.; Kawa, S. R.; Poole, L. R.

    1991-01-01

    The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. Most of the available chlorine (CHl and ClONO2) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl2O2 thoroughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO3, and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15 percent at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8 percent losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50 percent over the next two decades, ozone losses recognizable as an ozone hole may well appear.

  17. Dual Polarization Stacked Microstrip Patch Antenna Array With Very Low Cross-Polarization

    DEFF Research Database (Denmark)

    Granholm, Johan; Woelders, Kim

    2001-01-01

    This paper describes the development and performance of a wideband dual linear polarization microstrip antenna array used in the Danish high-resolution airborne multifrequency polarimetric synthetic aperture radar, EMISAR. The antenna was designed for an operating frequency of 1.25 GHz±50 MHz and...... was built as an array of 8×2 probe-fed stacked microstrip patches. The feeding network is constructed in microstrip and is capable of handling 6 kW of peak input-power at an altitude of 45000 ft (unpressurized). The impedance bandwidth (return loss better than -14 dB) of the antenna is 10%, the...... isolation between the horizontal and the vertical ports of the array is 50 dB and the cross-polarization suppression is 40 dB. A new design principle for simultaneously achieving very low cross-polarization and low side lobes in dual linear polarization antenna arrays has been applied...

  18. Spin structure of constituent quark and polarized structure of hadrons

    International Nuclear Information System (INIS)

    Polarized parton distribution inside a constituent quark is calculated. This structure is universal for all hadrons and the polarized structure of any hadron is a convolution of polarized constituent quark distribution in the hadron with the polarized structure function of the constituent quark. This approach gives very good agreement with the experimental data on polarized proton, neutron, and deuteron. However, in order to assemble the components to build the spin the constituent quark we are forced to include a sizeable orbital angular momentum. (author)

  19. High-altitude adaptations in vertebrate hemoglobins

    DEFF Research Database (Denmark)

    Weber, Roy E.

    2007-01-01

    ’s intrinsic O2-affinity and its allosteric interaction with cellular effectors (organic phosphates, protons and chloride). Whereas short-term altitudinal adaptations predominantly involve adjustments in allosteric interactions, long-term, genetically-coded adaptations typically involve changes in the....... Molecular heterogeneity (multiple isoHbs with differentiated oxygenation properties) can further broaden the range of physico-chemical conditions where Hb functions under altitudinal hypoxia. This treatise reviews the molecular and cellular mechanisms that adapt haemoglobin-oxygen affinities in mammals......, birds and ectothermic vertebrates at high altitude....

  20. Regression of altitude-produced cardiac hypertrophy.

    Science.gov (United States)

    Sizemore, D. A.; Mcintyre, T. W.; Van Liere, E. J.; Wilson , M. F.

    1973-01-01

    The rate of regression of cardiac hypertrophy with time has been determined in adult male albino rats. The hypertrophy was induced by intermittent exposure to simulated high altitude. The percentage hypertrophy was much greater (46%) in the right ventricle than in the left (16%). The regression could be adequately fitted to a single exponential function with a half-time of 6.73 plus or minus 0.71 days (90% CI). There was no significant difference in the rates of regression for the two ventricles.

  1. High altitude balloon experiments at IIA

    Science.gov (United States)

    Nayak, Akshata; Sreejith, A. G.; Safonova, Margarita; Murthy, Jayant

    Recent advances in balloon experiments as well as in electronics have made it possible to fly scientific payloads at costs accessible to university departments. We have begun a program of high altitude ballooning at the Indian Institute of Astrophysics, Bengaluru. The primary purpose of this activity is to test low-cost ultraviolet (UV) payloads for eventual space flight, but we will also try scientific exploration of the phenomena occurring in the upper atmosphere, including sprites and meteorite impacts. We present the results of the initial experiments carried out at the CREST campus of IIA, Hosakote, and describe our plans for the future.

  2. Ion gun operations at high altitudes

    OpenAIRE

    Werner, Paul W.

    1988-01-01

    Experiments in charge control were conducted on the P78-2 (SCATHA) satellite as part of a program on spacecraft charging at high altitudes. Experiments with the SCATHA ion gun were monitored by charged particle detectors and the electric field experiment. It was found that the electric field experiment could be used to measure satellite potential during ion beam emission in sunlight and eclipse. Unneutralized ion beam emission in high energy (1-2 KeV) and high current (1-2 mA) modes resulted ...

  3. Polarized proton collisions at 205 GeV at RHIC.

    Science.gov (United States)

    Bai, M; Roser, T; Ahrens, L; Alekseev, I G; Alessi, J; Beebe-Wang, J; Blaskiewicz, M; Bravar, A; Brennan, J M; Bruno, D; Bunce, G; Courant, E; Drees, A; Fischer, W; Gardner, C; Gill, R; Glenn, J; Haeberli, W; Huang, H; Jinnouchi, O; Kewisch, J; Luccio, A; Luo, Y; Nakagawa, I; Okada, H; Pilat, F; Mackay, W W; Makdisi, Y; Montag, C; Ptitsyn, V; Satogata, T; Stephenson, E; Svirida, D; Tepikian, S; Trbojevic, D; Tsoupas, N; Wise, T; Zelenski, A; Zeno, K; Zhang, S Y

    2006-05-01

    The Brookhaven Relativistic Heavy Ion Collider (RHIC) has been providing collisions of polarized protons at a beam energy of 100 GeV since 2001. Equipped with two full Siberian snakes in each ring, polarization is preserved during acceleration from injection to 100 GeV. However, the intrinsic spin resonances beyond 100 GeV are about a factor of 2 stronger than those below 100 GeV making it important to examine the impact of these strong intrinsic spin resonances on polarization survival and the tolerance for vertical orbit distortions. Polarized protons were first accelerated to the record energy of 205 GeV in RHIC with a significant polarization measured at top energy in 2005. This Letter presents the results and discusses the sensitivity of the polarization survival to orbit distortions. PMID:16712305

  4. Ascent schedules, acute altitude illness, and altitude acclimatization: Observations on the Yushu Earthquake

    Institute of Scientific and Technical Information of China (English)

    Wu Tianyi; Hou Shike; Li Shuzhi; Li Wenxiang; Gen Deng

    2013-01-01

    During the Yushu Earthquake on April 14,2010,a large number of rescuers from sea level or lowlands ascended to the quake areas very rapidly or rapidly less than 24 h.However,Yushu Earthquake is the highest quake in the world at altitudes between 3750 m and 4878 m where is a serious hypoxic environment.A high incidence of acute altitude illness was found in the unacclimatized rescuers; the mountain rescue operation changed as "rescue the rescuers".Lesson from the Yushu Earthquake is that the occurrence of acute altitude illness may be closely related to the ascent schedules.This prompted us to study the relationship between ascent rate and the incidence and severity of acute altitude illness; five different groups were compared.The first group was 42 sea level male young soldiers who ascended to quake area very rapidly within 8 h at 4000 m; the second group was 48 sea level male young soldiers who ascended to 4000 m rapidly less than 18 h; the third group was 66 acclimatized medical workers from 2261 m who ascended to 4000 m rapidly within 12 h; the fourth group was 56 Tibetan medical workers from 2800 m who ascended to 4000 m rapidly within 8 h; the fifth group was 50 male sea level workers who ascended to 4000 m gradually over a period of 4 d.The results showed that the sea level rescuers ascended to 4000 m very rapidly or rapidly had the highest incidence of acute mountain sickness (AMS) with the greatest AMS scores and the lowest arterial oxygen saturation (SaO2) ; the sea level workers ascended to 4000 m gradually had moderate incidence of AMS with moderate AMS scores and SaO2 values; whereas the acclimatized and adapted rescuers had the lowest incidence of AMS,lowest AMS scores and higher SaO2; especially none AMS occurred in Tibetan rescuers.AMS score is inversely related to the ascent rate (r=-0.24,p<0.001).Additionally,acute altitude illness is significantly influenced by altitude acclimatization.The ascent rate is inversely related to

  5. Europa Planetary Protection for Juno Jupiter Orbiter

    Science.gov (United States)

    Bernard, Douglas E.; Abelson, Robert D.; Johannesen, Jennie R.; Lam, Try; McAlpine, William J.; Newlin, Laura E.

    2010-01-01

    NASA's Juno mission launched in 2011 and will explore the Jupiter system starting in 2016. Juno's suite of instruments is designed to investigate the atmosphere, gravitational fields, magnetic fields, and auroral regions. Its low perijove polar orbit will allow it to explore portions of the Jovian environment never before visited. While the Juno mission is not orbiting or flying close to Europa or the other Galilean satellites, planetary protection requirements for avoiding the contamination of Europa have been taken into account in the Juno mission design.The science mission is designed to conclude with a deorbit burn that disposes of the spacecraft in Jupiter's atmosphere. Compliance with planetary protection requirements is verified through a set of analyses including analysis of initial bioburden, analysis of the effect of bioburden reduction due to the space and Jovian radiation environments, probabilistic risk assessment of successful deorbit, Monte-Carlo orbit propagation, and bioburden reduction in the event of impact with an icy body.

  6. DAWN Framing Camera results from Ceres orbit

    Science.gov (United States)

    Nathues, A.; Hoffmann, M.; Schäfer, M.; Le Corre, L.; Reddy, V.; Platz, T.; Russel, C. T.; Li, J.-Y.; Ammanito, E.; Buettner, I.; Christensen, U.; Hall, I.; Kelley, M.; Gutiérrez Marqués, P.; McCord, T. B.; McFadden, L. A.; Mengel, K.; Mottola, S.; O'Brien, D.; Pieters, C.

    2015-10-01

    Having completed its investigation of Vesta in late 2012, the NASA Dawn mission [1] reached its second target, the dwarf planet Ceres on March 6, 2015. During its operational phase, Dawn is scheduled to fly four polar orbits, each with a different distance to the target. The Framing Cameras (FCs) onboard the Dawn spacecraft are mapping the dwarf planet Ceres in seven colors and a clear filter [2], covering the wavelength range between 0.4 and 1.0 μm. The FCs also conduct a number of sequences for purposes of navigation, instrument calibration, and have already performed satellite searches and three early rotational characterizations (RCs) of Ceres in February and May 2015. During the EPSC conference we intend to present the most intriguing results obtained from the Survey orbit (resolution ~400 m/pixel) as well as the first results from HAMO orbit (~140 m/pixel) focusing on the analysis of FC color data.

  7. Spin transport in graphene spin–orbit barrier structure

    International Nuclear Information System (INIS)

    We studied spin-dependent transport in monolayer graphene with a spin–orbit barrier, a narrow strip in which the spin–orbit interaction is not zero. When the Fermi energy is between the two spin-split bands, the structure can be used to generate spin-polarized current. For a strong enough Rashba strength, a thick enough barrier or a low enough Fermi energy, highly spin-polarized current is generated (polarization ∼0.7–0.85). Under these conditions, the spin direction of the transmitted electron is approximately perpendicular to the direction of motion. This shows that graphene spin–orbit nanostructures are useful for the development of graphene spintronic devices.

  8. Generation of Orbital Angular Momentum Carrying Beams in Semiconductor Microcavities

    International Nuclear Information System (INIS)

    Full text: It is notable that all techniques for the creation of beams with orbital angular momentum, to the best of our knowledge, require an optically inhomogeneous and/or anisotropic material or strong focusing. In this work, we demonstrate that the spin-to-orbital angular momentum (SOAM) conversion can also be achieved in a planar semiconductor microcavity. Despite being an isotropic system, microcavities exhibit a polarization splitting between transverse electric - transverse magnetic (TE-TM) modes, which induces the appearance of an L = +2 orbital angular momentum in one of the circular polarizations, under excitation in the cross-circular polarization [1]. The vertical entities resulting from this conversion process can be regarded as the optical equivalent of a pair of half-quantum vortices. We provide a theoretical model which rigorously derives the principle of the SOAM conversion and quantitatively reproduces the experimental observations. (author)

  9. Long-period polar rain variations, solar wind and hemispherically symmetric polar rain

    International Nuclear Information System (INIS)

    On the basic of electron data obtained by the Defense Meteorological Satellite Program (DMSP) F2 satellite the long-period variations of the polar rain flux are examined for four consecutive solar rotations. It is clearly demonstrated that the asymmetric enhancement of the polar rain flux is strongly controlled by the sector structure of the interplanetary magnetic field (IMF). However, the orbit-to-orbit and day-to-day variations of the polar rain flux are detected even during a very stable sector period, and the polar rain flux does not have any clear relationship to the magnitude of the IMF B/sub x/ or B/sub y/. Thus the polarity of B/sub x/ controls only the accessibility of a polar region. It is also noticed that the intensity of polar rain fluxes does not show any relationship to the density of the solar wind, suggesting that the origin of the polar rain electrons is different from the commonly observed part of the solar wind electron distribution function. In addition to the asymmetric polar rain distribution, increasing polar rain fluxes of similar high intensity are sometimes detected over both polar caps. An examination of more than 1 year's data from the DMSP F2 and F4 satellites shows that simultaneous intense uniform precipitations (>107 electrons/cm2 s sr) over both polar caps are not coincidental; it also shows that the spectra are similar. The occurrence of hemispherically symmetric events is not common. They generally are observed after an IMF sector transition period, during unstable periods in the sector structure, and while the solar wind density is high. copyright American Geophysical Union 1987

  10. Full simulation of the LUCID experiment in the Low Earth Orbit radiation environment

    International Nuclear Information System (INIS)

    The Langton Ultimate Cosmic ray Intensity Detector (LUCID) experiment is a satellite-based device that uses five Timepix hybrid silicon pixel detectors to make measurements of the radiation environment at an altitude of approximately 630 km, i.e. in Low Earth Orbit (LEO) . The experiment launched aboard Surrey Satellite Technology Limited's (SSTL's) TechDemoSat-1 on Tuesday the 8th of July 2014. The Timepix detectors, developed by the Medipix2 Collaboration, are arranged to form the five sides of a cube enclosed by a 0.7 mm thick aluminium covering, and are operated in Time-over-Threshold (ToT) mode to allow the flux, energy and directionality of incident ionising radiation to be measured. To understand the expected detector performance with respect to these measurements, the LUCID experiment has been modelled using the Allpix software package, a generic simulation toolkit for silicon pixel detectors built upon the GEANT4 framework. The work presented here summarises studies completed using the GridPP Collaboration's computing grid infrastructure to perform the simulations, store the resultant datasets, and share that data with the LUCID Collaboration. The analysis of these datasets has given an indication of the expected performance in differing space radiation environments (for example, during passes of the polar regions or the South Atlantic Anomaly), and has allowed the LUCID Collaboration to prepare for when data is transmitted back to Earth in late 2014

  11. Exploration for fossil and nuclear fuels from orbital altitudes. [results of ERTS program for oil exploration

    Science.gov (United States)

    Short, N. M.

    1974-01-01

    Results from the ERTS program pertinent to exploration for oil, gas, and uranium are discussed. A review of achievements in relevant geological studies from ERTS, and a survey of accomplishments oriented towards exploration for energy sources are presented along with an evaluation of the prospects and limitations of the space platform approach to fuel exploration, and an examination of continuing programs designed to prove out the use of ERTS and other space system in exploring for fuel resources.

  12. Neonatal orbital abscess

    Directory of Open Access Journals (Sweden)

    Khalil M Al-Salem

    2014-01-01

    Full Text Available Orbital complications due to ethmoiditis are rare in neonates. A case of orbital abscess due to acute ethmoiditis in a 28-day-old girl is presented. A Successful outcome was achieved following antimicrobial therapy alone; spontaneous drainage of the abscess occurred from the lower lid without the need for surgery. From this case report, we intend to emphasize on eyelid retraction as a sign of neonatal orbital abscess, and to review all the available literature of similar cases.

  13. Quark Orbital Angular Momentum

    OpenAIRE

    Burkardt Matthias

    2015-01-01

    Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asy...

  14. Pictorial essay: Orbital tuberculosis

    International Nuclear Information System (INIS)

    Tuberculosis of the orbit is rare, even in places where tuberculosis is endemic. The disease may involve soft tissue, the lacrimal gland, or the periosteum or bones of the orbital wall. Intracranial extension, in the form of extradural abscess, and infratemporal fossa extension has been described. This pictorial essay illustrates the imaging findings of nine histopathologically confirmed cases of orbital tuberculosis. All these patients responded to antituberculous treatment

  15. Preseptal and Orbital Cellulitis

    OpenAIRE

    Emine Akçay; Gamze Dereli Can; Nurullah Çağıl

    2014-01-01

    Preseptal cellulitis (PC) is defined as an inflammation of the eyelid and surrounding skin, whereas orbital cellulitis (OC) is an inflammation of the posterior septum of the eyelid affecting the orbit and its contents. Periorbital tissues may become infected as a result of trauma (including insect bites) or primary bacteremia. Orbital cellulitis generally occurs as a complication of sinusitis. The most commonly isolated organisms are Staphylococcus aureus, Streptococcus pneumoniae, S. epid...

  16. Average thermospheric wind patterns over the polar regions, as observed by CHAMP

    Directory of Open Access Journals (Sweden)

    H. Lühr

    2007-06-01

    Full Text Available Measurements of the CHAMP accelerometer are utilized to investigate the average thermospheric wind distribution in the polar regions at altitudes around 400 km. This study puts special emphasis on the seasonal differences in the wind patterns. For this purpose 131 days centered on the June solstice of 2003 are considered. Within that period CHAMP's orbit is precessing once through all local times. The cross-track wind estimates of all 2030 passes are used to construct mean wind vectors for 918 equal-area cells. These bin averages are presented in corrected geomagnetic coordinates. Both hemispheres are considered simultaneously providing summer and winter responses for the same prevailing geophysical conditions. The period under study is characterized by high magnetic activity (Kp=4− but moderate solar flux level (F10.7=124. Our analysis reveals clear wind features in the summer (Northern Hemisphere. Over the polar cap there is a fast day-to-night flow with mean speeds surpassing 600 m/s in the dawn sector. At auroral latitudes we find strong westward zonal winds on the dawn side. On the dusk side, however, an anti-cyclonic vortex is forming. The dawn/dusk asymmetry is attributed to the combined action of Coriolis and centrifugal forces. Along the auroral oval the sunward streaming plasma causes a stagnation of the day-to-night wind. This effect is particularly clear on the dusk side. On the dawn side it is evident only from midnight to 06:00 MLT. The winter (Southern Hemisphere reveals similar wind features, but they are less well ordered. The mean day-to-night wind over the polar cap is weaker by about 35%. Otherwise, the seasonal differences are mainly confined to the dayside (06:00–18:00 MLT. In addition, the larger offset between geographic and geomagnetic pole in the south also causes hemispheric differences of the thermospheric wind distribution.

  17. First climatology of polar mesospheric clouds from GOMOS/ENVISAT stellar occultation instrument

    Directory of Open Access Journals (Sweden)

    D. Fussen

    2009-11-01

    Full Text Available GOMOS (Global Ozone Monitoring by Occultation of Stars, on board the European platform ENVISAT launched in 2002, is a stellar occultation instrument combining four spectrometers and two fast photometers which measure light at 1 kHz sampling rate in the two visible channels 470–520 nm and 650–700 nm. On the day side, GOMOS does not measure only the light from the star, but also the solar light scattered by the atmospheric molecules. In the summer polar days, Polar Mesospheric Clouds (PMC are clearly detected using the photometers signals, as the solar light scattered by the cloud particles in the instrument field of view. The sun-synchronous orbit of ENVISAT allows observing PMC in both hemispheres and the stellar occultation technique ensures a very good geometrical registration. Four years of data, from 2002 to 2006, are analyzed up to now. GOMOS data set consists of approximately 10 000 cloud observations all over the eight PMC seasons studied. The first climatology obtained by the analysis of this data set is presented, focusing on the seasonal and latitudinal coverage, represented by global maps. GOMOS photometers allow a very sensitive PMC detection, showing a frequency of occurrence of 100% in polar regions during the middle of the PMC season. According to this work mesospheric clouds seem to be more frequent in the Northern Hemisphere than in the Southern Hemisphere. The PMC altitude distribution was also calculated. The obtained median values are 82.7 km in the North and 83.2 km in the South.

  18. Average thermospheric wind patterns over the polar regions, as observed by CHAMP

    Science.gov (United States)

    Lühr, H.; Rentz, S.; Ritter, P.; Liu, H.; Häusler, K.

    2007-06-01

    Measurements of the CHAMP accelerometer are utilized to investigate the average thermospheric wind distribution in the polar regions at altitudes around 400 km. This study puts special emphasis on the seasonal differences in the wind patterns. For this purpose 131 days centered on the June solstice of 2003 are considered. Within that period CHAMP's orbit is precessing once through all local times. The cross-track wind estimates of all 2030 passes are used to construct mean wind vectors for 918 equal-area cells. These bin averages are presented in corrected geomagnetic coordinates. Both hemispheres are considered simultaneously providing summer and winter responses for the same prevailing geophysical conditions. The period under study is characterized by high magnetic activity (Kp=4-) but moderate solar flux level (F10.7=124). Our analysis reveals clear wind features in the summer (Northern) Hemisphere. Over the polar cap there is a fast day-to-night flow with mean speeds surpassing 600 m/s in the dawn sector. At auroral latitudes we find strong westward zonal winds on the dawn side. On the dusk side, however, an anti-cyclonic vortex is forming. The dawn/dusk asymmetry is attributed to the combined action of Coriolis and centrifugal forces. Along the auroral oval the sunward streaming plasma causes a stagnation of the day-to-night wind. This effect is particularly clear on the dusk side. On the dawn side it is evident only from midnight to 06:00 MLT. The winter (Southern) Hemisphere reveals similar wind features, but they are less well ordered. The mean day-to-night wind over the polar cap is weaker by about 35%. Otherwise, the seasonal differences are mainly confined to the dayside (06:00-18:00 MLT). In addition, the larger offset between geographic and geomagnetic pole in the south also causes hemispheric differences of the thermospheric wind distribution.

  19. First climatology of polar mesospheric clouds from GOMOS/ENVISAT stellar occultation instrument

    Directory of Open Access Journals (Sweden)

    K. Pérot

    2010-03-01

    Full Text Available GOMOS (Global Ozone Monitoring by Occultation of Stars, on board the European platform ENVISAT launched in 2002, is a stellar occultation instrument combining four spectrometers and two fast photometers which measure light at 1 kHz sampling rate in the two visible channels 470–520 nm and 650–700 nm. On the day side, GOMOS does not measure only the light from the star, but also the solar light scattered by the atmospheric molecules. In the summer polar days, Polar Mesospheric Clouds (PMC are clearly detected using the photometers signals, as the solar light scattered by the cloud particles in the instrument field of view. The sun-synchronous orbit of ENVISAT allows observing PMC in both hemispheres and the stellar occultation technique ensures a very good geometrical registration. Four years of data, from 2002 to 2006, are analyzed up to now. GOMOS data set consists of approximately 10 000 cloud observations all over the eight PMC seasons studied. The first climatology obtained by the analysis of this data set is presented, focusing on the seasonal and latitudinal coverage, represented by global maps. GOMOS photometers allow a very sensitive PMC detection, showing a frequency of occurrence of 100% in polar regions during the middle of the PMC season. According to this work mesospheric clouds seem to be more frequent in the Northern Hemisphere than in the Southern Hemisphere. The PMC altitude distribution was also calculated. The obtained median values are 82.7 km in the North and 83.2 km in the South.

  20. UoGAS - A Get Away Special Satellite with Orbit-Raising Capability

    OpenAIRE

    Lorenz, Ralph

    1988-01-01

    The low cost of satellite deployment from Shuttle GAS canister makes it an attractive launch option. However, the low deployment altitude severely constrains lifetime so the UoGAS (University of Surrey Get Away Special) spacecraft will incorporate a propulsion system. Lifetime extension methods are considered and a start-of-mission orbit-raising manoeuvre is selected. An orbit dynamics simulation method (taking into account the atmospheric drag) is discussed and results presented. Mission pro...

  1. Geometric orbit datum and orbit covers

    Institute of Scientific and Technical Information of China (English)

    LIANG; Ke(

    2001-01-01

    [1]Vogan, D. , Dixmier algebras, sheets and representation theory (in Actes du colloque en I' honneur de Jacques Dixmier),Progress in Math. 92, Boston: Birkhauser Verlag, 1990, 333-397.[2]McGovern, W., Dixmier Algebras and Orbit Method, Operator Algebras, Unitary Representations and Invariant Theory,Boston: Birkhauser, 1990, 397-416.[3]Liang, K. , Parabolic inductions of nilpotent geometric orbit datum, Chinese Science Bulletin (in Chinese) , 1996, 41 (23):2116-2118.[4]Vogan, D., Representations of Real Reductive Lie Groups, Boston-Basel-Stuttgart: Birkhauser, 1981.[5]Lustig, G., Spaltenstein, N., Induced unipotent class, J. London Math. Soc., 1997, 19. 41-52.[6]Collingwood, D. H. , McGovern, W. M. , Nilpotent Orbits in Semisimple Lie Algebras, New York: Van Nostremt Reinhold,1993.

  2. Kursk Magnetic Anomaly at Satellite Altitude: Revisited with the Orsted Satellite

    Science.gov (United States)

    Taylor, Patrick T.; VonFrese, Ralph R. B.; Kim, Hyung Rae

    2000-01-01

    The Kursk Magnetic Anomaly (KMA) of Russia (51 deg north, 37 deg east) has long been recognized as one of the largest magnetic anomalies on Earth. It is associated with the massive iron-ore formations of this region, however, model studies have revealed that the relationship between the two is not obvious. In an early effort to demonstrate the validity of Magsat data for crustal research a detailed study of the KMA, at an average altitude of 350 km and the surrounding region was made. They recorded a 27 nT high and a -9 nT low giving a 37 nT peak-to-trough anomaly over the immediate area of the KMA. Despite the much higher altitude of Orsted (620 to 850 km) we revisited the KMA to determine if this mission would also be able to record an associated anomalous crustal signature. The Orsted profiles we selected were from April to August 1999. From these data we chose those with an altitude range of 644 to 700 km and they were subsequently gridded, by least-squares collocation, to a mean elevation of 660 km. Both ascending and descending data were examined and signals common to both were extracted and averaged. A correlation coefficient between these two orbit orientations of 0.82 was computed. The quadrant-swapping method of Kim et al. was applied. Removal of the main geomagnetic field was accomplished with a polynomial fitting procedure. A positive anomaly of >2.5 nT with ari associated negative of 3 nT peak-to-trough range were computed. These Magsat and Orsted results are consistent with the decay of a dipole field over the studied altitude range. Significant differences between these two anomaly fields are due to the greater number of orbit profiles and therefore greater number of intersecting orbits (ascending and descending) available in the Orsted compilation. Of the four largest amplitude anomalies in the Orsted field three are present in the Magsat map. The fourth (>2.5 nT), however, is associated with the Belorussian-Lithuanian anteclise. This sugaests that

  3. Undulator radiation carrying spin and orbital angular momentum

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Shigemi [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)], E-mail: sasaki@aps.anl.gov; McNulty, Ian; Dejus, Roger [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2007-11-11

    We show that the radiation from a helical undulator not only carries spin angular momentum (circular polarization) but also orbital angular momentum. This exotic property of the undulator radiation may be useful in coherent X-ray imaging and scattering experiments and to probe electronic transitions in matter by orbital dichroism spectroscopy. Also, we present that a new magnet configuration, similar to the structure of Figure-8 undulator or the PERA undulator, may generate right- and left-hand circularly polarized off-axis radiation simultaneously.

  4. Undulator radiation carrying spin and orbital angular momentum.

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, S.; McNulty, I.; Dejus, R.; X-Ray Science Division

    2007-11-11

    We show that the radiation from a helical undulator not only carries spin angular momentum (circular polarization) but also orbital angular momentum. This exotic property of the undulator radiation may be useful in coherent X-ray imaging and scattering experiments and to probe electronic transitions in matter by orbital dichroism spectroscopy. Also, we present that a new magnet configuration, similar to the structure of Figure-8 undulator or the PERA undulator, may generate right- and left-hand circularly polarized off-axis radiation simultaneously.

  5. A Future Polarized Drell-Yan Experiment at Fermilab

    International Nuclear Information System (INIS)

    The topic is treated in a series of slides under the following headings: Motivation (Nucleon Spin Puzzle, Quark Orbital Momentum and the Sivers Function, Accessing Sivers via Polarized Drell-Yan (p+p↑ → μ+μ-)); Transition of Seaquest (E906 → E1039) (Building a Polarized proton Target, Status of Polarized Target); and Outlook. The nucleon spin puzzle: when the quark and gluon contributions to the proton spin are evaluated, nearly 50% of the measured spin is missing; lattice QCD calculations indicate as much as 50% may come from quark orbital angular momentum. Sea quarks should carry orbital angular momentum (O.A.M.). The E1039 Polarized Target Drell-Yan Experiment provides opportunity to study possible Sea Quark O.A.M. Data taking is expected to begin in the spring of 2017.

  6. A Future Polarized Drell-Yan Experiment at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Kleinjan, David William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-06-04

    The topic is treated in a series of slides under the following headings: Motivation (Nucleon Spin Puzzle, Quark Orbital Momentum and the Sivers Function, Accessing Sivers via Polarized Drell-Yan (p+p↑ → μ+μ-)); Transition of Seaquest (E906 → E1039) (Building a Polarized proton Target, Status of Polarized Target); and Outlook. The nucleon spin puzzle: when the quark and gluon contributions to the proton spin are evaluated, nearly 50% of the measured spin is missing; lattice QCD calculations indicate as much as 50% may come from quark orbital angular momentum. Sea quarks should carry orbital angular momentum (O.A.M.). The E1039 Polarized Target Drell-Yan Experiment provides opportunity to study possible Sea Quark O.A.M. Data taking is expected to begin in the spring of 2017.

  7. Characterizing Longitude-Dependent Orbital Debris Congestion in the Geosynchronous Orbit Regime

    Science.gov (United States)

    Anderson, Paul V.

    The geosynchronous orbit (GEO) is a unique commodity of the satellite industry that is becoming increasingly contaminated with orbital debris, but is heavily populated with high-value assets from the civil, commercial, and defense sectors. The GEO arena is home to hundreds of communications, data transmission, and intelligence satellites collectively insured for an estimated 18.3 billion USD. As the lack of natural cleansing mechanisms at the GEO altitude renders the lifetimes of GEO debris essentially infinite, conjunction and risk assessment must be performed to safeguard operational assets from debris collisions. In this thesis, longitude-dependent debris congestion is characterized by predicting the number of near-miss events per day for every longitude slot at GEO, using custom debris propagation tools and a torus intersection metric. Near-miss events with the present-day debris population are assigned risk levels based on GEO-relative position and speed, and this risk information is used to prioritize the population for debris removal target selection. Long-term projections of debris growth under nominal launch traffic, mitigation practices, and fragmentation events are also discussed, and latitudinal synchronization of the GEO debris population is explained via node variations arising from luni-solar gravity. In addition to characterizing localized debris congestion in the GEO ring, this thesis further investigates the conjunction risk to operational satellites or debris removal systems applying low-thrust propulsion to raise orbit altitude at end-of-life to a super-synchronous disposal orbit. Conjunction risks as a function of thrust level, miss distance, longitude, and semi-major axis are evaluated, and a guidance method for evading conjuncting debris with continuous thrust by means of a thrust heading change via single-shooting is developed.

  8. Bronchial asthma: advice for patients traveling to high altitude.

    Science.gov (United States)

    Cogo, Annalisa; Fiorenzano, Giuseppe

    2009-01-01

    This article examines the possibility of traveling to altitude for patients suffering from bronchial asthma. The mountain environment, the adaptations of the respiratory system to high altitude, the underlying patho-physiologies of asthma, and the recommendations for patients, according to altitude, are discussed. In summary, staying at low altitude has a significant beneficial effect for asthmatic patients, due to the reduction of airway inflammation and the lower response to bronchoconstrictor stimuli; for staying at moderate altitude, there is conflicting information and no clinical data; at high altitude, the environment seems beneficial for well-controlled asthmatics, but intense exercise and upper airway infections (frequent during trekking) can be additional risks and should be avoided. Further, in remote areas health facilities are often difficult to reach. PMID:19519226

  9. Multi-agent Orbit Design for Visual Perception Enhancement Purpose

    Directory of Open Access Journals (Sweden)

    Hamidreza Nourzadeh

    2014-10-01

    Full Text Available This paper develops a robust optimization-based method to design orbits on which the sensory perception of the desired physical quantities are maximized. It also demonstrates how to incorporate various constraints imposed by many spacecraft missions, such as collision avoidance, co-orbital configuration, altitude and frozen orbit constraints along with Sun-synchronous orbit constraints. The paper specifically investigates designing orbits for constrained visual sensor planning applications as its case study. For this purpose, the key elements to form an image in such vision systems are considered and effective factors are taken into account to define a metric for perception quality. The method employs a max-min model to ensure robustness against possible perturbations and model uncertainties. While fulfilling the mission requirements, the algorithm devises orbits on which a higher level collective observation quality for the desired sides of the targets is available. The simulation results confirm the effectiveness of the proposed method for several scenarios involving low and medium Earth orbits as well as a challenging space-based space surveillance program application.

  10. Tether de-orbiting of satellites at end of mission

    Science.gov (United States)

    Sanmartin, Juan R.; Sánchez-Torres, Antonio

    2012-07-01

    The accumulation of space debris around the Earth has become critical for Space security. The BETs project, financed by the European Commission through its FP7-Space program, is focusing on preventing generation of new debris by de-orbiting satellites at end of mission. The de-orbiting system considered, involving an electrodynamic bare tape-tether, uses no propellant and no power supply, while generating power for on-board use during de-orbiting. As an example, preliminary results are here presented on a specific orbit/satellite case: 1300 km altitude and 65 degrees inclination, and 500 kg mass. Design tether dimensions are 8 km length, 1.5 cm width, and 0.05 mm thickness; subsystem masses are limited to twice tether mass. Simple calculations, using orbit-averaging, solar mid-cycle phase, and ionospheric and geomagnetic field models, yield 2.6 months time for de-orbiting down to 200 km, with a probability of about 1 percent of debris cutting the tape. References: Sanmartin, J.R., Lorenzini, E.C., and Martinez-Sanchez, M., Electrodynamic Tether Applications and Constraints, J. Space. Rockets 47, 442-456, 2010. Sanmartin, J.R. et al., A universal system to de-orbit satellites at end of life, Journal of Space Technology and Science, to appear.

  11. Semicircular Rashba arc spin polarizer

    International Nuclear Information System (INIS)

    In this work, we study the generation of spin polarized currents using curved arcs of finite widths, in which the Rashba spin orbit interaction (RSOI) is present. Compared to the 1-dimensional RSOI arcs with zero widths studied previously, the finite width presents charge carriers with another degree of freedom along the transverse width of the arc, in addition to the longitudinal degree of freedom along the circumference of the arc. The asymmetry in the transverse direction due to the difference in the inner and outer radii of the arc breaks the antisymmetry of the longitudinal spin z current in a straight RSOI segment. This property can be exploited to generate spin z polarized current output from the RSOI arc by a spin unpolarized current input. The sign of the spin current can be manipulated by varying the arc dimensions

  12. Semicircular Rashba arc spin polarizer

    Energy Technology Data Exchange (ETDEWEB)

    Bin Siu, Zhuo, E-mail: a0018876@nus.edu.sg [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore); Advanced Concepts and Nanotechnology, Data Storage Institute, DSI Building, 5 Engineering Drive 1 (Off Kent Ridge Crescent, NUS), Singapore 117608 (Singapore); Jalil, Mansoor B. A. [NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 (Singapore); Ghee Tan, Seng [Advanced Concepts and Nanotechnology, Data Storage Institute, DSI Building, 5 Engineering Drive 1 (Off Kent Ridge Crescent, NUS), Singapore 117608 (Singapore)

    2014-05-07

    In this work, we study the generation of spin polarized currents using curved arcs of finite widths, in which the Rashba spin orbit interaction (RSOI) is present. Compared to the 1-dimensional RSOI arcs with zero widths studied previously, the finite width presents charge carriers with another degree of freedom along the transverse width of the arc, in addition to the longitudinal degree of freedom along the circumference of the arc. The asymmetry in the transverse direction due to the difference in the inner and outer radii of the arc breaks the antisymmetry of the longitudinal spin z current in a straight RSOI segment. This property can be exploited to generate spin z polarized current output from the RSOI arc by a spin unpolarized current input. The sign of the spin current can be manipulated by varying the arc dimensions.

  13. Features of ion trajectories in the polar magnetosphere

    International Nuclear Information System (INIS)

    The trajectories of mainly low-energy ionosphere ions injected near the polar cusp into the polar magnetosphere are presented for a model polar magnetosphere including the effects of convection electric fields and gravitation. The trajectories display the ion mass and energy differentiation which has been seen in recent satellite observations of low-energy ionospheric ions injected into the polar magnetosphere, and indicate that for reasonable ranges of injectrion energy, pitch angle and convection electric field: 1. Transport of low-energy 'polar cusp' 0+ to the approx.1 Re altitude nightside auroral acceleration region is feasible; and 2. Preferential trapping of energetic 0+ relative to H+ and He+ energetic ions occur in the closed field line region of the magnetotail plasma sheet. Two interesting classes of polar region very low-energy heavy ion trajectories are noted: 1. 'Parabolic' trajectories, in which heavy ions injected at the polar cusp at small pitch angle rise then fall into the polar cap atmosphere, and 2. 'Hopping' trajectories, in which heavy ions injected at large pitch angles at the polar cusp mirror beteen the gravitational stopping location and magnetic mirror point as they convect at low to intermediate altitudes across the polar cap. It was also illustrated how during conditions of sunward convection in the central polar cap, a pronounced 'spray' of ions injected on the nightside may occur, in which such ions may appear in the nightside or dayside magnetosphere depending upon injection characteristics and dusk-to-dawn convection electric field magnitude; such ion dynamics may be of interest in connection with thse auroras

  14. The physiology and biomechanics of avian flight at high altitude

    OpenAIRE

    Altshuler, Douglas L.; Dudley, Robert

    2006-01-01

    Many birds fly at high altitude, either during long-distance flights or by virtue of residence in high-elevation habitats. Among the many environmental features that vary systematically with altitude, five have significant consequences for avian flight performance: ambient wind speeds, air temperature, humidity, oxygen availability, and air density. During migratory flights, birds select flight altitudes that minimize energy expenditure via selection of advantageous tail- and cross-winds. Oxy...

  15. Work at high altitude and oxidative stress: antioxidant nutrients.

    Science.gov (United States)

    Askew, E W

    2002-11-15

    A significant portion of the world's geography lies above 10,000 feet elevation, an arbitrary designation that separates moderate and high altitude. Although the number of indigenous people living at these elevations is relatively small, many people travel to high altitude for work or recreation, exposing themselves to chronic or intermittent hypoxia and the associated risk of acute mountain sickness (AMS) and less frequently, high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). The symptoms of AMS (headache, nausea, anorexia, fatigue, lassitude) occur in those who travel too high, too fast. Some investigators have linked the development of these symptoms with the condition of altered blood-brain barrier permeability, possibly related to hypoxia induced free radical formation. The burden of oxidative stress increases during the time spent at altitude and may even persist for some time upon return to sea level. The physiological and medical consequences of increased oxidative stress engendered by altitude is unclear; indeed, hypoxia is believed to be the trigger for the cascade of signaling events that ultimately leads to adaptation to altitude. These signaling events include the generation of reactive oxygen species (ROS) that may elicit important adaptive responses. If produced in excess, however, these ROS may contribute to impaired muscle function and reduced capillary perfusion at altitude or may even play a role in precipitating more serious neurological and pulmonary crisis. Oxidative stress can be observed at altitude without strenuous physical exertion; however, environmental factors other than hypoxia, such as exercise, UV light exposure and cold exposure, can also contribute to the burden. Providing antioxidant nutrients via the diet or supplements to the diet can reduce oxidative stress secondary to altitude exposure. In summary, the significant unanswered question concerning altitude exposure and antioxidant supplementation is

  16. Altitude, Immigration and Suicide Rates: A Study from Turkey

    OpenAIRE

    Selek, Salih

    2013-01-01

    Objective To investigate the altitude, immigration and suicide rates association in Turkey. Methods Suicide and immigration rates of 81 provinces and their elevation data were obtained. Results There were not significant correlations between country elevation, immigration and mean suicide rate. Conclusion The findings of this study points out that altitude related hypoxia and suicide association may not be generalized and further research will be needed to clarify the effects of altitude on s...

  17. Genomic insights into adaptation to high-altitude environments

    OpenAIRE

    Cheviron, Z A; Brumfield, R. T.

    2011-01-01

    Elucidating the molecular genetic basis of adaptive traits is a central goal of evolutionary genetics. The cold, hypoxic conditions of high-altitude habitats impose severe metabolic demands on endothermic vertebrates, and understanding how high-altitude endotherms cope with the combined effects of hypoxia and cold can provide important insights into the process of adaptive evolution. The physiological responses to high-altitude stress have been the subject of over a century of research, and r...

  18. The effect of acetazolamide on breath holding at high altitude.

    OpenAIRE

    Morrissey, S. C.; Keohane, K.; Coote, J.H.

    1987-01-01

    The effect of altitude and acetazolamide on breath holding was studied in 20 individuals. Breath holding time was reduced progressively during ascent. There was an additional reduction in the acetazolamide group at low but not at high altitude. The initial difference between the two groups may have been related to a lower CSF pH when on acetazolamide. At high altitude the finding of similar breath holding times in the two groups may have been due to acclimatization in the placebo group.

  19. High-Altitude Illnesses: Physiology, Risk Factors, Prevention, and Treatment

    OpenAIRE

    Taylor, Andrew T.

    2011-01-01

    High-altitude illnesses encompass the pulmonary and cerebral syndromes that occur in non-acclimatized individuals after rapid ascent to high altitude. The most common syndrome is acute mountain sickness (AMS) which usually begins within a few hours of ascent and typically consists of headache variably accompanied by loss of appetite, nausea, vomiting, disturbed sleep, fatigue, and dizziness. With millions of travelers journeying to high altitudes every year and sleeping above 2,500 m, acute m...

  20. Plasticity of the muscle proteome to exercise at altitude

    OpenAIRE

    Flueck, Martin

    2009-01-01

    The ascent of humans to the summits of the highest peaks on Earth initiated a spurt of explorations into the physiological consequences of physical activity at altitude. The past three decades have demonstrated that the resetting of respiratory and cardiovascular control with chronic exposure to altitudes above 4000 m is accompanied by important structural-functional adjustments of skeletal muscle. The fully altitude-adapted phenotype preserves energy charge at reduced aerobic capacity throug...

  1. An oxygen enrichment device for lowlanders ascending to high altitude

    OpenAIRE

    Shen, Guanghao; Wu, Xiaoming; Tang, Chi; Yan, Yili; LIU, JUAN; Guo, Wei; Jing, Da; Lei, Tao; Tian, Yue; Xie, Kangning; Luo, Erping; Zhang, Jianbao

    2013-01-01

    Background When ascending to the high altitude, people living in low altitude areas will suffer from acute mountain sickness. The aim of this study is to test the hypothesis that whether an oxygen concentration membrane can be made and used to construct a new portable oxygen enrichment device for individuals in acute exposure to the high altitude. Methods The membrane was fabricated using vinylsiloxane rubber, polyphenylene oxide hydrogen silicone polymers, chloroplatinic acid and isopropyl a...

  2. Respiratory Function of University Students Living at High Altitude

    OpenAIRE

    Roh, HyoLyun; Lee, Daehee

    2014-01-01

    [Purpose] This study compared the respiratory function and oxygen saturation levels of university students living at high altitude, to present a new approach for improving respiratory function using high altitudes above sea level. [Subjects and Methods] The subjects were 100 female students attending a university located approximately 850 m above sea level and 104 female students attending a university located at low altitude. Oxygen saturation, heart rate (HR), and respiratory function level...

  3. Genetic and phenotypic differentiation of an Andean intermediate altitude population

    OpenAIRE

    Eichstaedt, Christina A; Antão, Tiago; Cardona, Alexia; Pagani, Luca; Kivisild, Toomas; Mormina, Maru

    2015-01-01

    Highland populations living permanently under hypobaric hypoxia have been subject of extensive research because of the relevance of their physiological adaptations for the understanding of human health and disease. In this context, what is considered high altitude is a matter of interpretation and while the adaptive processes at high altitude (above 3000 m) are well documented, the effects of moderate altitude (below 3000 m) on the phenotype are less well established. In this study, we compar...

  4. Common High Altitudes Illnesses a Primer for Healthcare Provider

    OpenAIRE

    Mohsenin, Vahid

    2015-01-01

    Exposure to high altitude imposes significant strain on cardiopulmonary system and the brain. As a consequence, sojourners to high altitude frequently experience sleep disturbances, often reporting restless and sleepless nights. At altitudes above 3,000 meters (9,800 ft) almost all healthy subjects develop periodic breathing especially during NREM sleep. Sleep architecture gradually improves with increased NREM and REM sleep despite persistence of periodic breathing. The primary reason for pe...

  5. Parameterization of middle atmospheric water vapor photochemistry for high-altitude NWP and data assimilation

    Directory of Open Access Journals (Sweden)

    J. P. McCormack

    2008-12-01

    Full Text Available This paper describes CHEM2D-H2O, a new parameterization of H2O photochemical production and loss based on the CHEM2D photochemical-transport model of the middle atmosphere. This parameterization accounts for the altitude, latitude, and seasonal variations in the photochemical sources and sinks of water vapor over the pressure region from 100–0.001 hPa (~16–90 km altitude. A series of free-running NOGAPS-ALPHA forecast model simulations offers a preliminary assessment of CHEM2D-H2O performance over the June 2007 period. Results indicate that the CHEM2D-H2O parameterization improves global 10-day forecasts of upper mesospheric water vapor compared to forecasts using an existing one-dimensional (altitude only parameterization. Most of the improvement is seen at high winter latitudes where the one-dimensional parameterization specifies photolytic H2O loss year round despite the lack of sunlight in winter. The new CHEM2D-H2O parameterization should provide a better representation of the downwelling of dry mesospheric air into the stratospheric polar vortex in operational analyses that do not assimilate middle atmospheric H2O measurements.

  6. Parameterization of middle atmospheric water vapor photochemistry for high-altitude NWP and data assimilation

    Directory of Open Access Journals (Sweden)

    J. P. McCormack

    2008-07-01

    Full Text Available This report describes CHEM2D-H2O, a new parameterization of H2O photochemical production and loss based on the CHEM2D photochemical-transport model of the middle atmosphere. This parameterization accounts for the altitude, latitude, and seasonal variations in the photochemical sources and sinks of water vapor over the pressure region from 100–0.001 hPa (~16–90 km altitude. A series of free-running NOGAPS-ALPHA forecast model simulations offers a preliminary assessment of CHEM2D-H2O performance over the June 2007 period. Results indicate that the CHEM2D-H2O parameterization improves global 10-day forecasts of upper mesospheric water vapor compared to forecasts using an existing one-dimensional (altitude only parameterization. Most of the improvement is seen at high winter latitudes where the one-dimensional parameterization specifies photolytic H2O loss year round despite the lack of sunlight in winter. The new CHEM2D-H2O parameterization should provide a better representation of the downwelling of dry mesospheric air into the stratospheric polar vortex in operational analyses that do not assimilate middle atmospheric H2O measurements.

  7. Globally Polarized Quark-gluon Plasma in Non-central A+ACollisions

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Zuo-tang; Wang, Xin-Nian

    2004-10-01

    Produced partons have large local relative orbital angular momentum along the direction opposite to the reaction plane in the early stage of non-central heavy-ion collisions. Parton scattering is shown to polarize quarks along the same direction due to spin-orbital coupling.Such global quark polarization will lead to many observable consequences,such as left-right asymmetry of hadron spectra, global transverse polarization of thermal photons, dileptons and hadrons. Hadrons from the decay of polarized resonances will have azimuthal asymmetry similar to the elliptic flow. Global hyperon polarization is predicted with indifferent hadronization scenarios and can be easily tested.

  8. Tunnelling of orbital angular momentum in parallel optical waveguides

    International Nuclear Information System (INIS)

    We study the evolution of circularly polarized optical vortices (OVs) in the system of two coupled few-mode optical fibres. We demonstrate that upon propagation OVs tunnel into the adjacent fibre as a complex superposition of OVs that comprise also OVs of opposite polarization and topological charge. The initial OV may tunnel into the other fibre as the same vortex state of lesser energy. The evolution of the orbital angular momentum in coupled fibres is studied

  9. Preliminary Planning for NEAR's Low-Altitude Operations at 433 Eros

    Science.gov (United States)

    Antreasian, P. G.; Helfrich, C. L.; Miller, J. K.; Owen, W. M.; Williams, B. G.; Yeomans, D. K.; Scheeres, D. J.; Dunham, D. W.; Farquhar, R. W.; McAdams, J. V.

    1999-01-01

    On February 14, 2000, an orbit insertion burn will place NASA's Near Earth Asteroid Rendezvous (NEAR) spacecraft (S/C) into orbit around asteroid 433 Eros. NEAR will initially orbit Eros with distances ranging from 500 to 100 km in order to characterize the shape, gravity and spin of Eros. Once the physical parameters of Eros are determined reasonably well, the plan is to establish an orbit of the NEAR S/C with increasingly lower altitudes as the one year orbital mission progresses while further characterizing the gravity and shape of Eros. Towards the end of the NEAR mission, after the shape, gravity and spin of Eros have been well characterized, the scientific interest of obtaining very close observations (Eros, and onboard optical imaging of landmarks on Eros. This paper will provide preliminary plans for mission design and navigation during the last two months of the orbit phase, where several close passes to the surface will be incorporated to enhance the science return. The culmination of these close passes will result in the eventual landing of the S/C on the surface of Eros. Several considerations for these plans are given by Antreasian, et at. [1998]. The objective for the end of the mission will be to land the S/C autonomously using the surface relative information obtained from the onboard LIDAR instrument. The goal will be to soft land the S/C in such a way as to keep it operational. With the use of an onboard LIDAR landing algorithm as discussed by Antreasian et at. [1998], it is believed that the S/C impact velocity can be kept well under 7 m/s which is a requirement for allowing the S/C to remain operational.

  10. Neurophysiological Problems in Snow Bound High Altitude Areas

    Directory of Open Access Journals (Sweden)

    W. Selvamurthy

    1984-10-01

    Full Text Available A series of studies have been conducted to evaluate the neurophysiological responses in young healthy soldiers during acclimatization at 3,500m altitude in Western Himalayas. The responses of autonomic nervous system, electroencephalogram hypothalamic thermoregulatory efficiency, orthostatic tolerance, sleep profile and effects of sleep deprivation have been studied in fresh inductees during three to five weeks of acclimatization at high altitude and compared with those of one year acclimatized lowlanders and high altitude natives. Physiological significance of these neurophysiological responses in the process of altitude adaptation is discussed in the light of current knowledge in the field.

  11. Aviation fuel property effects on altitude relight

    Science.gov (United States)

    Venkataramani, K.

    1987-01-01

    The major objective of this experimental program was to investigate the effects of fuel property variation on altitude relight characteristics. Four fuels with widely varying volatility properties (JP-4, Jet A, a blend of Jet A and 2040 Solvent, and Diesel 2) were tested in a five-swirl-cup-sector combustor at inlet temperatures and flows representative of windmilling conditions of turbofan engines. The effects of fuel physical properties on atomization were eliminated by using four sets of pressure-atomizing nozzles designed to give the same spray Sauter mean diameter (50 + or - 10 micron) for each fuel at the same design fuel flow. A second series of tests was run with a set of air-blast nozzles. With comparable atomization levels, fuel volatility assumes only a secondary role for first-swirl-cup lightoff and complete blowout. Full propagation first-cup blowout were independent of fuel volatility and depended only on the combustor operating conditions.

  12. Cardiovascular Response to High Altitude Hypoxia

    Directory of Open Access Journals (Sweden)

    S. C. Manchanda

    1984-10-01

    Full Text Available Normal and abnormal cardiovascular response to high altitude (HA hypoxia were studied in 98 healthy subjects and in 15 patients with HA pulmonary oedema (HAPO and acute mountain sickness (AMS at an altitudeof 3,658 m. The healthy sea level (SL residents showed marked blood volume changes during the first week with pulmonary hypotension and depression of left ventricular (LV performance and physical work capacity (PWC. The HA natives, however, had better LV performance and PWC indicating a better adaptation to HA hypoxia. HAPO subjects showed evidence of severe pulmonary hypertension with normal left atrial pressures but the exact mechanism of this condition is still not clear. AMS subjects showed no circulatory abnormalities 'but had relative hypercapnia and severe hypoxemia suggesting that AMS may be causcd by relative hyposensitiveness of the respiratory centre to hypoxia or hypercapnia.

  13. Anticoagulation Considerations for Travel to High Altitude.

    Science.gov (United States)

    DeLoughery, Thomas G

    2015-09-01

    DeLoughery, Thomas G. Anticoagulation considerations for travel to high altitude. High Alt Med Biol 16:181-185, 2015.-An increasing percentage of the population are on anticoagulation medicine for clinical reasons ranging from stroke prevention in atrial fibrillation to long term prevention of deep venous thrombosis. In recent years, several new direct oral anticoagulants have entered the market. The key questions that should be kept in mind when approaching a potential traveler on anticoagulation are: 1) why is the patient on anticoagulation? 2) do they need to stay on anticoagulation? 3) what are the choices for their anticoagulation? 4) will there be any drug interactions with medications needed for travel? and 5) how will they monitor their anticoagulation while traveling? Knowing the answers to these questions then can allow for proper counseling and planning for the anticoagulated traveler's trip. PMID:26186419

  14. Polarization measurement and vertical aperture optimization for obtaining circularly polarized bend-magnet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kortright, J.B.; Rice, M.; Hussain, Z. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Growing interest in utilizing circular polarization prompted the design of bend-magnet beamline 9.3.2 at the Advanced Light Source, covering the 30-1500 eV spectral region, to include vertical aperturing capabilities for optimizing the collection of circular polarization above and below the orbit plane. After commissioning and early use of the beamline, a multilayer polarimeter was used to characterize the polarization state of the beam as a function of vertical aperture position. This report partially summarizes the polarimetry measurements and compares results with theoretical calculations intended to simulate experimental conditions.

  15. Bremsstrahlung polarization correlations and their application for polarimetry of electron beams

    International Nuclear Information System (INIS)

    The correlation between electron spin and photon linear polarization in atomic-field bremsstrahlung was measured with a polarized electron beam. The angle of photon polarization and the photon emission intensity were found to be correlated with the spin orientation. These effects are interpreted in terms of spin-orbit interaction. They lead to a new technique of electron beam polarimetry.

  16. High Altitude Supersonic Decelerator Test Vehicle

    Science.gov (United States)

    Cook, Brant T.; Blando, Guillermo; Kennett, Andrew; Von Der Heydt, Max; Wolff, John Luke; Yerdon, Mark

    2013-01-01

    The Low Density Supersonic Decelerator (LDSD) project is tasked by NASA's Office of the Chief Technologist (OCT) to advance the state of the art in Mars entry and descent technology in order to allow for larger payloads to be delivered to Mars at higher altitudes with better accuracy. The project will develop a 33.5 m Do Supersonic Ringsail (SSRS) parachute, 6m attached torus, robotic class Supersonic Inflatable Aerodynamic Decelerator (SIAD-R), and an 8 m attached isotensoid, exploration class Supersonic Inflatable Aerodynamic Decelerator (SIAD-E). The SSRS and SIAD-R should be brought to TRL-6, while the SIAD-E should be brought to TRL-5. As part of the qualification and development program, LDSD must perform a Mach-scaled Supersonic Flight Dynamics Test (SFDT) in order to demonstrate successful free flight dynamic deployments at Mars equivalent altitude, of all three technologies. In order to perform these tests, LDSD must design and build a test vehicle to deliver all technologies to approximately 180,000 ft and Mach 4, deploy a SIAD, free fly to approximately Mach 2, deploy the SSRS, record high-speed and high-resolution imagery of both deployments, as well as record data from an instrumentation suite capable of characterizing the technology induced vehicle dynamics. The vehicle must also be recoverable after splashdown into the ocean under a nominal flight, while guaranteeing forensic data protection in an off nominal catastrophic failure of a test article that could result in a terminal velocity, tumbling water impact.

  17. Mercury's Crustal Magnetic Field from Low-Altitude Measurements by MESSENGER.

    Science.gov (United States)

    Johnson, C. L.; Phillips, R. J.; Purucker, M. E.; Anderson, B. J.; Byrne, P. K.; Denevi, B. W.; Fan, K. A.; Feinberg, J. M.; Hauck, S. A., II; Head, J. W., III; Korth, H.; James, P. B.; Mazarico, E.; Neumann, G. A.; Philpott, L. C.; Siegler, M. A.; Strauss, B. E.; Tsyganenko, N. A.; Solomon, S. C.

    2015-12-01

    Magnetized rocks can record the history of a planet's magnetic field, a key constraint for understanding interior evolution. From orbital vector magnetic field measurements of Mercury taken by the MESSENGER spacecraft at altitudes below 150 km, we have detected fields indicative of crustal magnetization. Fields from non-crustal sources, which dominate the observations even at low altitudes, were estimated and subtracted from the observations using both magnetospheric models and signal filtering. The resulting high-pass filtered fields have amplitudes of a few to 20 nT. The first low-altitude signals were detected over the Suisei Planitia region and were confirmed by upward continuation to be of crustal origin. At least some contribution from thermoremanent magnetization is required to account for these signals, and we infer a lower bound on the average age of magnetization of 3.7-3.9 Ga on the basis of correlation of crustal magnetic fields with volcanic units of that age range. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust derived from MESSENGER elemental composition data. Here, we extend these initial results with observations obtained at spacecraft altitudes below 60 km at all body-fixed longitudes from ~40°N to ~75°N. The strongest crustal fields occur in the region 120°E to 210°E, and weaker signals characterize the northern volcanic plains. We test the hypothesis that the longest-wavelength crustal field signals in this region reflect magnetization contrasts between the Caloris basin and the surrounding intercrater plains and circum-Caloris plains. We report the spatial distribution of observed crustal fields, together with magnetization models derived from them and the implications of these models, particularly for the depth distribution of sources compatible with the observations.

  18. PLANECHG: Earth orbit to lunar orbit delta V estimation program. User and technical documentation

    Science.gov (United States)

    1988-01-01

    The PLANECNG computer program calculates velocities for Earth-to-Mooon and Moon-to-Earth trajectories. The flight to be analyzed originates in a circular orbit of any inclination and altitude about one of the bodies, and culminates in a circular orbit of any inclination and altitude about the other body. An intermedate delta V and plane change occurs at the Lunar Sphere of Influence (SOI), the region where the vehicle is near its lowest velocity in the trajectory, and therefore where it is able to make the plane change with the lowest delta V. A given flight may penetrate the SOI at a number of points. Each point has associated with it a unique set of delta V's and total velocity. The program displays the velocities, in matrix form, for a representative set of SOI penetration points. An SOI point is identified by projecting Lunar latitude and longitude onto the SOI. The points recorded for a given flight are defined by the user, who provides a starting longitude and latitude, and an increment for each. A matrix is built with 10 longitudes forming the columns and 19 latitudes forming the rows. This matrix is presented in six reports, each containing different velocity or node information in the body of the matrix.

  19. GPS Satellites Orbits: Resonance

    Directory of Open Access Journals (Sweden)

    Luiz Danilo Damasceno Ferreira

    2009-01-01

    Full Text Available The effects of perturbations due to resonant geopotential harmonics on the semimajor axis of GPS satellites are analyzed. For some GPS satellites, secular perturbations of about 4 m/day can be obtained by numerical integration of the Lagrange planetary equations considering in the disturbing potential the main secular resonant coefficients. Amplitudes for long-period terms due to resonant coefficients are also exhibited for some hypothetical satellites orbiting in the neighborhood of the GPS satellites orbits. The results are important to perform orbital maneuvers of GPS satellites such that they stay in their nominal orbits. Also, for the GPS satellites that are not active, the long-period effects due to the resonance must be taken into account in the surveillance of the orbital evolutions of such debris.

  20. Mechanisms of Altitude-Related Cough/Mécanismes de la Toux Liée à l’Altitude

    OpenAIRE

    Mason, Nicholas

    2012-01-01

    The original work presented in this thesis investigates some of the mechanisms that may be responsible for the aetiology of altitude-related cough. Particular attention is paid to its relationship to the long recognised, but poorly understood, changes in lung volumes that occur on ascent to altitude. The literature relevant to this thesis is reviewed in Chapter 1. Widespread reports have long existed of a debilitating cough affecting visitors to high altitude that can incapacitate the suff...

  1. On the evening time exosphere of Mars: Result from MENCA aboard Mars Orbiter Mission

    Science.gov (United States)

    Bhardwaj, Anil; Thampi, Smitha V.; Das, Tirtha Pratim; Dhanya, M. B.; Naik, Neha; Vajja, Dinakar Prasad; Pradeepkumar, P.; Sreelatha, P.; Supriya, G.; Abhishek J., K.; Mohankumar, S. V.; Thampi, R. Satheesh; Yadav, Vipin K.; Sundar, B.; Nandi, Amarnath; Padmanabhan, G. Padma; Aliyas, A. V.

    2016-03-01

    The Mars Exospheric Neutral Composition Analyser (MENCA) aboard the Indian Mars Orbiter Mission (MOM) is a quadrupole mass spectrometer which provides in situ measurement of the composition of the low-latitude Martian neutral exosphere. The altitude profiles of the three major constituents, i.e., amu 44 (CO2), amu 28 (N2 + CO), and amu 16 (O) in the Martian exosphere during evening (close to sunset terminator) hours are reported using MENCA observations from four orbits of MOM during late December 2014, when MOM's periapsis altitude was the lowest. The altitude range of the observation encompasses the diffusively separated region much above the well-mixed atmosphere. The transition from CO2 to O-dominated region is observed near 270 km. The mean exospheric temperature derived using these three mass numbers is 271 ± 5 K. These first observations corresponding to the Martian evening hours would help to provide constraints to the thermal escape models.

  2. Polarization measurement and vertical aperture optimization for obtaining circularly polarized bend-magnet radiation

    International Nuclear Information System (INIS)

    Using multilayer linear polarizers, we have characterized the polarization state of radiation from bend-magnet beamline 9.3.2 at the Advanced Light Source as a function of vertical opening angle at photon energies of 367 and 722 eV. Both a fine slit and a coarse semi-aperture were stepped across the beam to accept different portions of the vertical radiation fan. Polarimetry yields the degree of linear polarization directly and the degree of circular polarization indirectly assuming an immeasurably small amount of unpolarized radiation based on the close agreement of the theoretical and experimental results for linear polarization. The results are in good agreement with theoretical calculations, with departures from theory resulting from uncertainty in the effective aperture of the measured beam. The narrow 0.037-mrad aperture on the orbit plane transmits a beam whose degree of linear polarization exceeds 0.99 at these energies. The wide semi-aperture blocking the beam from above and below transmits a beam with a maximum figure of merit, given by the square root of flux times the degree of circular polarization, when the aperture edge is on the orbit plane thus blocking only half of the total available flux. copyright 1996 American Institute of Physics

  3. Polarization measurement and vertical aperture optimization for obtaining circularly polarized bend-magnet radiation

    International Nuclear Information System (INIS)

    Using multilayer linear polarizers, we have studied the polarization state of radiation from bend magnet beamline 9.3.2 at Advanced Light Source as function of vertical oping angle at photon energies 367 and 722 eV. Both a fine slit and a coarse semi-aperture were stepped across the beam to accept different parts of the vertical radiation fan. Polarimetry yields the degree of linear polarization directly and the degree of circular polarization indirectly assuming an immeasurably small amount of unpolarized radiation based on close agreement of theory and experiment for linear polarization. Results are in good agreement with theoretical calculations, with departures from theory owing to uncertainty in effective aperture of the measured beam. The narrow 0.037 mrad aperture on the orbit plane transmits a beam whose degree of linear polarization exceeds 0.99 at these energies. The wide semi-aperture blocking the beam from above and below transmits a beam with a max figure of merit, given by the square root of flux times degree of circular polarization, when the aperture edge is on the orbit plane thus blocking only half of the total available flux

  4. Experimental Evidence for Partonic Orbital Angular Momentum at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Fields, Douglas E. [University of New Mexico, Department of Physics and Astronomy, Albuquerque, NM 871331 (United States)

    2011-12-14

    Although one might naively anticipate that the proton, being the lowest baryonic energy state, would be in a L = 0 state, the current theoretical understanding is that it must carry orbital angular momentum in order, for example, to have a non-zero anomalous magnetic moment. I will review the experimental evidence linked theoretically to orbital angular momentum of the proton's constituents from the RHIC experiments and summarize by presenting a challenge to the theory community--to develop a consistent framework which can explain the spin polarization asymmetries seen at RHIC and elsewhere, and give insight to the partonic wave-functions including orbital angular momentum.

  5. Experimental Evidence for Partonic Orbital Angular Momentum at RHIC

    International Nuclear Information System (INIS)

    Although one might naively anticipate that the proton, being the lowest baryonic energy state, would be in a L = 0 state, the current theoretical understanding is that it must carry orbital angular momentum in order, for example, to have a non-zero anomalous magnetic moment. I will review the experimental evidence linked theoretically to orbital angular momentum of the proton's constituents from the RHIC experiments and summarize by presenting a challenge to the theory community--to develop a consistent framework which can explain the spin polarization asymmetries seen at RHIC and elsewhere, and give insight to the partonic wave-functions including orbital angular momentum.

  6. Modeling the Exo-Brake and the Development of Strategies for De-Orbit Drag Modulation

    Science.gov (United States)

    Murbach, M. S.; Papadopoulos, P.; Glass, C.; Dwyer-Cianciolo, A.; Powell, R. W.; Dutta, S.; Guarneros-Luna, A.; Tanner, F. A.; Dono, A.

    2016-01-01

    The Exo-Brake is a simple, non-propulsive means of de-orbiting small payloads from orbital platforms such as the International Space Station (ISS). Two de-orbiting experiments with fixed surface area Exo-Brakes have been successfully conducted in the last two years on the TechEdSat-3 and -4 nano-satellite missions. The development of the free molecular flow aerodynamic data-base is presented in terms of angle of attack, projected front surface area variation, and altitude. Altitudes are considered ranging from the 400km ISS jettison altitude to 90km. Trajectory tools are then used to predict de-orbit/entry corridors with the inclusion of the key atmospheric and geomagnetic uncertainties. Control system strategies are discussed which will be applied to the next two planned TechEdSat-5 and -6 nano-satellite missions - thus increasing the targeting accuracy at the Von Karman altitude through the proposed drag modulation technique.

  7. Effects of Geopotential and Atmospheric Drag Effects on Frozen Orbits Using Nonsingular Variables

    Directory of Open Access Journals (Sweden)

    Paula Cristiane Pinto Mesquita Pardal

    2014-01-01

    Full Text Available The concept of frozen orbit has been applied in space missions mainly for orbital tracking and control purposes. This type of orbit is important for orbit design because it is characterized by keeping the argument of perigee and eccentricity constant on average, so that, for a given latitude, the satellite always passes at the same altitude, benefiting the users through this regularity. Here, the system of nonlinear differential equations describing the motion is studied, and the effects of geopotential and atmospheric drag perturbations on frozen orbits are taken into account. Explicit analytical expressions for secular and long period perturbations terms are obtained for the eccentricity and the argument of perigee. The classical equations of Brouwer and Brouwer and Hori theories are used. Nonsingular variables approach is used, which allows obtaining more precise previsions for CBERS (China Brazil Earth Resources Satellite satellites family and similar satellites (SPOT, Landsat, ERS, and IRS orbital evolution.

  8. Observation of polar vortices in oxide superlattices.

    Science.gov (United States)

    Yadav, A K; Nelson, C T; Hsu, S L; Hong, Z; Clarkson, J D; Schlepütz, C M; Schlepüetz, C M; Damodaran, A R; Shafer, P; Arenholz, E; Dedon, L R; Chen, D; Vishwanath, A; Minor, A M; Chen, L Q; Scott, J F; Martin, L W; Ramesh, R

    2016-02-11

    The complex interplay of spin, charge, orbital and lattice degrees of freedom provides a plethora of exotic phases and physical phenomena. In recent years, complex spin topologies have emerged as a consequence of the electronic band structure and the interplay between spin and spin-orbit coupling in materials. Here we produce complex topologies of electrical polarization--namely, nanometre-scale vortex-antivortex (that is, clockwise-anticlockwise) arrays that are reminiscent of rotational spin topologies--by making use of the competition between charge, orbital and lattice degrees of freedom in superlattices of alternating lead titanate and strontium titanate layers. Atomic-scale mapping of the polar atomic displacements by scanning transmission electron microscopy reveals the presence of long-range ordered vortex-antivortex arrays that exhibit nearly continuous polarization rotation. Phase-field modelling confirms that the vortex array is the low-energy state for a range of superlattice periods. Within this range, the large gradient energy from the vortex structure is counterbalanced by the corresponding large reduction in overall electrostatic energy (which would otherwise arise from polar discontinuities at the lead titanate/strontium titanate interfaces) and the elastic energy associated with epitaxial constraints and domain formation. These observations have implications for the creation of new states of matter (such as dipolar skyrmions, hedgehog states) and associated phenomena in ferroic materials, such as electrically controllable chirality. PMID:26814971

  9. Effects of ascent to high altitude on human antimycobacterial immunity.

    Directory of Open Access Journals (Sweden)

    Sarah Eisen

    Full Text Available Tuberculosis infection, disease and mortality are all less common at high than low altitude and ascent to high altitude was historically recommended for treatment. The immunological and mycobacterial mechanisms underlying the association between altitude and tuberculosis are unclear. We studied the effects of altitude on mycobacteria and antimycobacterial immunity.Antimycobacterial immunity was assayed in 15 healthy adults residing at low altitude before and after they ascended to 3400 meters; and in 47 long-term high-altitude residents. Antimycobacterial immunity was assessed as the extent to which participants' whole blood supported or restricted growth of genetically modified luminescent Bacille Calmette-Guérin (BCG mycobacteria during 96 hours incubation. We developed a simplified whole blood assay that could be used by a technician in a low-technology setting. We used this to compare mycobacterial growth in participants' whole blood versus positive-control culture broth and versus negative-control plasma.Measurements of mycobacterial luminescence predicted the number of mycobacterial colonies cultured six weeks later. At low altitude, mycobacteria grew in blood at similar rates to positive-control culture broth whereas ascent to high altitude was associated with restriction (p ≤ 0.002 of mycobacterial growth to be 4-times less than in culture broth. At low altitude, mycobacteria grew in blood 25-times more than negative-control plasma whereas ascent to high altitude was associated with restriction (p ≤ 0.01 of mycobacterial growth to be only 6-times more than in plasma. There was no evidence of differences in antimycobacterial immunity at high altitude between people who had recently ascended to high altitude versus long-term high-altitude residents.An assay of luminescent mycobacterial growth in whole blood was adapted and found to be feasible in low-resource settings. This demonstrated that ascent to or residence at high altitude was

  10. Cassini observations of Saturn's southern polar cusp

    CERN Document Server

    Arridge, C S; Achilleos, N; Bogdanova, Y V; Bunce, E J; Cowley, S W H; Fazakerley, A N; Khurana, K K; Lamy, L; Leisner, J S; Roussos, E; Russell, C T; Zarka, P; Coates, A J; Dougherty, M K; Jones, G H; Krimigis, S M; Krupp, N

    2016-01-01

    The magnetospheric cusps are important sites of the coupling of a magnetosphere with the solar wind. The combination of both ground- and space-based observations at Earth have enabled considerable progress to be made in understanding the terrestrial cusp and its role in the coupling of the magnetosphere to the solar wind via the polar magnetosphere. Voyager 2 fully explored Neptune's cusp in 1989 but highly inclined orbits of the Cassini spacecraft at Saturn present the most recent opportunity to repeatedly studying the polar magnetosphere of a rapidly rotating planet. In this paper we discuss observations made by Cassini during two passes through Saturn's southern polar magnetosphere. Our main findings are that i) Cassini directly encounters the southern polar cusp with evidence for the entry of magnetosheath plasma into the cusp via magnetopause reconnection, ii) magnetopause reconnection and entry of plasma into the cusp can occur over a range of solar wind conditions, and iii) double cusp morphologies are...

  11. Diabatic Descent In The Stratospheric Polar Vortex

    Science.gov (United States)

    Rosenfield, J.; Schoeberl, M.

    Polar regions experience diabatic cooling during the fall and winter months, resulting in a downward mass flux. An accurate measure of this fall and winter diabatic descent, as well as an understanding of the transport of air into and out of the winter polar vor- tices, is required for estimates of polar ozone depletion. We have calculated diabatic cooling rates using a radiative transfer code and U.K. Met Office (UKMO) tempera- tures for the years 1992-2000. These cooling rates, together with UKMO horizontal winds, have been used to compute three-dimensional forward and backward diabatic trajectories for the seven month fall to spring period in both the NH and the SH. The forward calculations estimate the maximum amount of descent that can occur. How- ever, they are not necessarily a good indicator of the origin of the springtime vortex air because more equatorward air from lower altitudes can be entrained within the vortex during its formation. The back trajectories, starting in the springtime lower middle stratosphere, show a complex final distribution of parcels. One population originates in the fall in the upper stratosphere and mesosphere and experiences considerable de- scent, while the remaining parcels originate at lower altitudes in the midlatitudes and are mixed into the polar regions during vortex formation. The amount of descent ex- perienced by the first population shows little variability from year to year, while the computed descent and mixing of the remaining parcels show considerable interannual variability due to the varying polar meteorology. Because of this complex parcel dis- tribution it is not meaningful to speak of a net amount of descent experienced over the entire winter period. We have also compared diabatic trajectories with kinematic tra- jectories, in which the vertical motion is given by the UKMO analysed omega fields. These show that the kinematic trajectory descent is much less than the diabatic tra- jectory descent and exhibits

  12. Strong-gravity effects acting on polarization from orbiting spots

    Czech Academy of Sciences Publication Activity Database

    Karas, Vladimír

    Cambridge : Cambridge University Press, 2010 - (Bellazzini, R.; Costa, E.; Matt, G.; Tagliaferi, G.), s. 109-116 ISBN 978-0-521-19184-5. - (Cambridge Contemporary Astrophysics). [Coming age of X-ray polarimetry. Rome (IT), 27.04.2009-30.04.2009] R&D Projects: GA ČR GA202/09/0772; GA MŠk(CZ) LC06014 Institutional research plan: CEZ:AV0Z10030501 Keywords : astrophysics * polarimetry * X-rays Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  13. Orbital and spin variability of the Intermediate Polar BG CMi

    CERN Document Server

    Kim, Y G; Park, S S; Jeon, Y B

    2005-01-01

    Results of a CCD study of the variability of the cataclysmic variable BG CMi obtained at the Korean 1.8m telescope in 2002-2005 are presented. The "multi-comparison star" method had been applied for better accuracy estimates. The linear ephemeris based on 19 mean maxima for 2002--2005 is HJD 2453105.31448(6)+0.01057257716(198)(E-764707). The period differs from that predicted by the quadratic ephemeris by Pych et al. (1996) leading to a possible cycle miscount. The statistically optimal ephemeris is a fourth-order polynomial, as a quadratic or even a cubic ephemeris leads to unaceptably large residuals: Min.HJD=$ 2445020.28095(28)+0.0105729609(57)E -1.58(32)\\cdot10^{-13}E^2-5.81(64)\\cdot10^{-19}E^3+4.92(41)\\cdot10^{-25}E^4.$ Thus the rate of the spin-up of the white dwarf is decreasing. An alternative explanation is that the spin-up has been stopped during recent years. The deviations between the amplutudes of the spin variability in V and R, as well as between phases are not statistically significant. Howeve...

  14. Spin rectification by orbital polarization in Bi-bilayer nanoribbons.

    Science.gov (United States)

    Jin, Kyung-Hwan; Jhi, Seung-Hoon

    2016-03-16

    We investigate the edge states of quantum spin-Hall phase Bi(111) bilayer nano-ribbons (BNRs) and their spin-rectifying effect using first-principles calculations and a non-equilibrium transport method. As low-dimensional materials, BNRs have tunable electronic properties, which are not only dependent on the edge shape, chemical passivation, or external electric fields but also governed by geometrical deformation. Depending on the passivation types, the interaction of the helical edge states in BNRs exhibits various patterns, enabling the valley engineering of the Dirac cones. In addition, the spin texture of the Dirac state is significantly tuned by edge passivation, external electric fields and geometric deformations. We demonstrate that curved BNRs can be used as the spin valves to rectify the electric currents via the edge states. Our results provide a practical way of utilizing two-dimensional topological insulator Bi bilayers for spintronic devices. PMID:26947010

  15. Harmonically excited orbital variations

    International Nuclear Information System (INIS)

    Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs

  16. Imaging of orbital disorders.

    Science.gov (United States)

    Cunnane, Mary Beth; Curtin, Hugh David

    2016-01-01

    Diseases of the orbit can be categorized in many ways, but in this chapter we shall group them according to etiology. Inflammatory diseases of the orbits may be infectious or noninfectious. Of the infections, orbital cellulitis is the most common and typically arises as a complication of acute sinusitis. Of the noninfectious, inflammatory conditions, thyroid orbitopathy is the most common and results in enlargement of the extraocular muscles and proliferation of the orbital fat. Idiopathic orbital inflammatory syndrome is another cause of inflammation in the orbit, which may mimic thyroid orbitopathy or even neoplasm, but typically presents with pain. Masses in the orbit may be benign or malignant and the differential diagnosis primarily depends on the location of the mass lesion, and on the age of the patient. Lacrimal gland tumors may be lymphomas or epithelial lesions of salivary origin. Extraocular muscle tumors may represent lymphoma or metastases. Tumors of the intraconal fat are often benign, typically hemangiomas or schwannomas. Finally, globe tumors may be retinoblastomas (in children), or choroidal melanomas or metastases in adults. PMID:27432687

  17. Visual-Motion Cueing in Altitude and Yaw Control

    Science.gov (United States)

    Johnson, Walter W.; Schroeder, Jeffery; Statler, Irving C. (Technical Monitor)

    1994-01-01

    Research conducted using the Vertical Motion Simulator at the NASA Ames Research Center examined the contributions of platform motion and visual level-of-detail (LOD) cueing to tasks that required altitude and/or yaw control in a simulated AH-64 Apache helicopter. Within the altitude control tasks the LOD manipulation caused optical density to change across altitudes by a small, moderate, or large amount; while platform motion was either present or absent. The results from these tasks showed that both constant optical density and platform motion improved altitude awareness in an altitude repositioning task, while the presence of platform motion also led to improved performance in a vertical rate control task. The yaw control tasks had pilots'sit 4.5 ft in front of the center of rotation, thus subjecting them to both rotational and lateral motions during a yaw. The pilots were required to regulate their yaw, while the platform motion was manipulated in order to present all combinations of the resulting rotational and lateral motion components. Ratings of simulation fidelity and sensed platform motion showed that the pilots were relatively insensitive to the rotational component, but highly aware of the lateral component. Together these findings show that: 1) platform motion cues are important when speed regulation is required during altitude change; 2) platform motion contributes to the perception of movement amplitude; 3) lateral, but not rotational, motion cues are essential to the perception of vehicle yaw; and 4) LOD management yielding constant optical density across altitudes improves altitude awareness.

  18. 14 CFR 121.661 - Initial approach altitude: Flag operations.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Initial approach altitude: Flag operations... OPERATING REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Dispatching and Flight Release Rules § 121.661 Initial approach altitude: Flag operations. When making an initial approach to a...

  19. 14 CFR 91.177 - Minimum altitudes for IFR operations.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Minimum altitudes for IFR operations. 91.177 Section 91.177 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Instrument Flight Rules § 91.177 Minimum altitudes for IFR operations. (a) Operation of aircraft at...

  20. Sequencing of 50 human exomes reveals adaptation to high altitude

    DEFF Research Database (Denmark)

    Yi, Xin; Liang, Yu; Huerta-Sanchez, Emilia;

    2010-01-01

    Residents of the Tibetan Plateau show heritable adaptations to extreme altitude. We sequenced 50 exomes of ethnic Tibetans, encompassing coding sequences of 92% of human genes, with an average coverage of 18x per individual. Genes showing population-specific allele frequency changes, which repres...... in genetic adaptation to high altitude....

  1. Altitude acclimatization. Citations from the International Aerospace Abstracts data base

    Science.gov (United States)

    Mauk, S. C.

    1980-01-01

    This bibliography of citations to the international literature covers aspects of altitude acclimatization. Included are articles concerning high altitude environments, hypoxia, heart function and hemodynamic responses, physical exercise, human tolerances and reactions, physiological responses, and oxygen consumption. This updated bibliography contains 164 citations, 35 of which are new entries to the previous edition.

  2. Exercise and Training at Altitudes: Physiological Effects and Protocols

    Directory of Open Access Journals (Sweden)

    Olga Cecilia Vargas Pinilla

    2014-01-01

    Full Text Available An increase in altitude leads to a proportional fall in the barometric pressure, and a decrease in atmospheric oxygen pressure, producing hypobaric hypoxia that affects, in different degrees, all body organs, systems and functions. The chronically reduced partial pressure of oxygen causes that individuals adapt and adjust to physiological stress. These adaptations are modulated by many factors, including the degree of hypoxia related to altitude, time of exposure, exercise intensity and individual conditions. It has been established that exposure to high altitude is an environmental stressor that elicits a response that contributes to many adjustments and adaptations that influence exercise capacity and endurance performance. These adaptations include in crease in hemoglobin concentration, ventilation, capillary density and tissue myoglobin concentration. However, a negative effect in strength and power is related to a decrease in muscle fiber size and body mass due to the decrease in the training intensity. Many researches aim at establishing how training or living at high altitudes affects performance in athletes. Training methods, such as living in high altitudes training low, and training high-living in low altitudes have been used to research the changes in the physical condition in athletes and how the physiological adaptations to hypoxia can enhanceperformance at sea level. This review analyzes the literature related to altitude training focused on how physiological adaptations to hypoxic environments influence performance, and which protocols are most frequently used to train in high altitudes.

  3. Increased resting bronchial tone in normal subjects acclimatised to altitude

    OpenAIRE

    Wilson, C.; Bakewell, S; M. Miller; Hart, N; McMorrow, R; BARRY, P.; Collier, D; Watt, S; Pollard, A.

    2002-01-01

    Background: Normal subjects frequently experience troublesome respiratory symptoms when acclimatised to altitude. Bronchial hyperresponsiveness (BHR) and full and partial flow-volume loops were measured before and after ascent to 5000 m altitude to determine if there are changes in resting bronchial tone and BHR that might explain the symptoms.

  4. Spin Orbit Torque in Ferromagnetic Semiconductors

    KAUST Repository

    Li, Hang

    2016-06-21

    Electrons not only have charges but also have spin. By utilizing the electron spin, the energy consumption of electronic devices can be reduced, their size can be scaled down and the efficiency of `read\\' and `write\\' in memory devices can be significantly improved. Hence, the manipulation of electron spin in electronic devices becomes more and more appealing for the advancement of microelectronics. In spin-based devices, the manipulation of ferromagnetic order parameter using electrical currents is a very useful means for current-driven operation. Nowadays, most of magnetic memory devices are based on the so-called spin transfer torque, which stems from the spin angular momentum transfer between a spin-polarized current and the magnetic order parameter. Recently, a novel spin torque effect, exploiting spin-orbit coupling in non-centrosymmetric magnets, has attracted a massive amount of attention. This thesis addresses the nature of spin-orbit coupled transport and torques in non-centrosymmetric magnetic semiconductors. We start with the theoretical study of spin orbit torque in three dimensional ferromagnetic GaMnAs. Using the Kubo formula, we calculate both the current-driven field-like torque and anti-damping-like torque. We compare the numerical results with the analytical expressions in the model case of a magnetic Rashba two-dimensional electron gas. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described. Subsequently we study spin-orbit torques in two dimensional hexagonal crystals such as graphene, silicene, germanene and stanene. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. This thesis then addresses the influence of the quantum spin Hall

  5. The use of vertical cut-off rigidities in computations of cosmic ray spectra on the Earth's orbits

    International Nuclear Information System (INIS)

    Simplified assumptions for computing spectral probabilities of cosmic rays transmission into the geomagnetic field are used to estimate their flux and energy spectra on low altitude orbits. For this purpose, three types of planetary tables of vertical cut-off rigidities and two approaches are used for their extrapolations from the Earth's surface to the altitude of satellite. A comparison of the results leads to errors insignificant in estimation of the radiation exposure by cosmic rays influenced by the geomagnetic field at low altitudes. (author)

  6. Bell's measure and implementing quantum Fourier transform with orbital angular momentum of classical light.

    Science.gov (United States)

    Song, Xinbing; Sun, Yifan; Li, Pengyun; Qin, Hongwei; Zhang, Xiangdong

    2015-01-01

    We perform Bell's measurement for the non-separable correlation between polarization and orbital angular momentum from the same classical vortex beam. The violation of Bell's inequality for such a non-separable classical correlation has been demonstrated experimentally. Based on the classical vortex beam and non-quantum entanglement between the polarization and the orbital angular momentum, the Hadamard gates and conditional phase gates have been designed. Furthermore, a quantum Fourier transform has been implemented experimentally. PMID:26369424

  7. Microgravity combustion experiment using high altitude balloon.

    Science.gov (United States)

    Kan, Yuji

    In JAXA, microgravity experiment system using a high altitude balloon was developed , for good microgravity environment and short turn-around time. In this publication, I give an account of themicrogravity experiment system and a combustion experiment to utilize the system. The balloon operated vehicle (BOV) as a microgravity experiment system was developed from 2004 to 2009. Features of the BOV are (1) BOV has double capsule structure. Outside-capsule and inside-capsule are kept the non-contact state by 3-axis drag-free control. (2) The payload is spherical shape and itsdiameter is about 300 mm. (3) Keep 10-4 G level microgravity environment for about 30 seconds However, BOV’s payload was small, and could not mount large experiment module. In this study, inherits the results of past, we established a new experimental system called “iBOV” in order toaccommodate larger payload. Features of the iBOV are (1) Drag-free control use for only vertical direction. (2) The payload is a cylindrical shape and its size is about 300 mm in diameter and 700 mm in height. (3) Keep 10-3-10-4 G level microgravity environment for about 30 seconds We have "Observation experiment of flame propagation behavior of the droplets column" as experiment using iBOV. This experiment is a theme that was selected first for technical demonstration of iBOV. We are conducting the flame propagation mechanism elucidation study of fuel droplets array was placed at regular intervals. We conducted a microgravity experiments using TEXUS rocket ESA and drop tower. For this microgravity combustion experiment using high altitude balloon, we use the Engineering Model (EM) for TEXUS rocket experiment. The EM (This payload) consists of combustion vessel, droplets supporter, droplets generator, fuel syringe, igniter, digital camera, high-speed camera. And, This payload was improved from the EM as follows. (1) Add a control unit. (2) Add inside batteries for control unit and heater of combustion

  8. Are Orbitals Observable?

    Directory of Open Access Journals (Sweden)

    Peter Mulder

    2011-07-01

    Full Text Available In this paper I discuss the question whether orbitals can be observed or not. I argue that the answer depends on how the terms 'orbitals' and 'observed' are understood. The fact that different authors take radically different stances on the issue is caused by their employing different uses of either of the two terms. I furthermore discuss a recent argument by Labarca and Lombardi to the effect that the orbital concept in chemistry is discontinuous with that in quantum mechanics. I argue that, quite to the contrary, there is continuity between the two.

  9. Satellites orbits and missions

    CERN Document Server

    Capderou, Michel

    2006-01-01

    Introduction Keplerian motion 1.1 Preamble 1.2 Acceleration 1.3 Central acceleration 1.4 Newtonian acceleration 1.5 Keplerian motion : trajectory and period 1.6 The three anomalies 1.7 Representation of the anomalies 1.8 Integrals of motion 1.9 Historical note on universal attraction 1.10 Annex : Ellipses Satellites on keplerian orbit 2.1 Gravitational field 2.2 The N-body and the two-body problem 2.3 Orbital parameters 2.4 Case of quasi-circular orbits 2.5 Keplerian period Satellites on real o

  10. Quark Orbital Angular Momentum

    Directory of Open Access Journals (Sweden)

    Burkardt Matthias

    2015-01-01

    Full Text Available Definitions of orbital angular momentum based on Wigner distributions are used as a framework to discuss the connection between the Ji definition of the quark orbital angular momentum and that of Jaffe and Manohar. We find that the difference between these two definitions can be interpreted as the change in the quark orbital angular momentum as it leaves the target in a DIS experiment. The mechanism responsible for that change is similar to the mechanism that causes transverse single-spin asymmetries in semi-inclusive deep-inelastic scattering.

  11. Helioseismology with Solar Orbiter

    OpenAIRE

    Löptien, Björn; Birch, Aaron C.; Gizon, Laurent; Schou, Jesper; Appourchaux, Thierry; Rodríguez, Julián Blanco; Cally, Paul S.; Dominguez-Tagle, Carlos; Gandorfer, Achim; Hill, Frank; Hirzberger, Johann; Scherrer, Philip H.; Solanki, Sami K.

    2014-01-01

    The Solar Orbiter mission, to be launched in July 2017, will carry a suite of remote sensing and in-situ instruments, including the Polarimetric and Helioseismic Imager (PHI). PHI will deliver high-cadence images of the Sun in intensity and Doppler velocity suitable for carrying out novel helioseismic studies. The orbit of the Solar Orbiter spacecraft will reach a solar latitude of up to 21 deg (up to 34 deg by the end of the extended mission) and thus will enable the first local helioseismol...

  12. General introduction to altitude adaptation and mountain sickness

    DEFF Research Database (Denmark)

    Bartsch, P.; Saltin, B.

    2008-01-01

    over 24-48 h to improve the oxygen-carrying capacity of the blood, and is further improved during a prolonged sojourn at altitude through an enhanced erythropoiesis and larger Hb mass, allowing for a partial or full restoration of the blood volume and arterial oxygen content. Most of these adaptations......-30% of subjects at altitudes between 2500 and 3000 m a.s.l. Pulmonary edema is rarely seen below 3000 m a.s.l. and brain edema is not seen below 4000 m a.s.l. It is possible to travel to altitudes of 2500-3000 m a.s.l., wait for 2 days, and then gradually start to train. At higher altitudes, one should...... modalities using hypoxia and altitude for improvement of performance Udgivelsesdato: 2008/8...

  13. Penta prism laser polarizer.

    Science.gov (United States)

    Lotem, H; Rabinovitch, K

    1993-04-20

    A novel type of laser prism polarizer is proposed. The polarizer is characterized by a high transmission efficiency, a high optical damage threshold, and a high extinction ratio. The polarizer is shaped like a regular penta prism and, thus, it is a constant deviation angle device. Polarization effects occur upon the two internal cascade reflections in the prism. Anisotropic and Isotropic types of the polarizer are discussed. The isotropic polarizer is a prism made of a high refractive-index glass coated by multilayer polarization-type dielectric coatings. Efficient s-state polarization is obtained because of p-state leakage upon the two internal cascade reflections. The anisotropic polarizer is made of a birefringent crystal in which angular polarization splitting is obtained by the bireflectance (double-reflection) effect. Fanning of a laser beam into up to eight polarized beams is possible in a prism made of a biaxial crystal. PMID:20820335

  14. Orbital angular momentum of general astigmatic modes

    International Nuclear Information System (INIS)

    We present an operator method to obtain complete sets of astigmatic Gaussian solutions of the paraxial wave equation. In case of general astigmatism, the astigmatic intensity and phase distribution of the fundamental mode differ in orientation. As a consequence, the fundamental mode has a nonzero orbital angular momentum, which is not due to phase singularities. Analogous to the operator method for the quantum harmonic oscillator, the corresponding astigmatic higher-order modes are obtained by repeated application of raising operators on the fundamental mode. The nature of the higher-order modes is characterized by a point on a sphere, in analogy with the representation of polarization on the Poincare sphere. The north and south poles represent astigmatic Laguerre-Gaussian modes, similar to circular polarization on the Poincare sphere, while astigmatic Hermite-Gaussian modes are associated with points on the equator, analogous to linear polarization. We discuss the propagation properties of the modes and their orbital angular momentum, which depends on the degree of astigmatism and on the location of the point on the sphere

  15. Shielding distribution for anisotropic radiation in low earth orbit

    International Nuclear Information System (INIS)

    The highly directional nature of radiation encountered in low earth orbit (LEO) can be a basis for distributing mass for spacecraft radiation shielding. Trapped (Van Allen) radiation at low altitudes is concentrated within a plane perpendicular to the local geometric field lines. Trapped high-energy protons (which penetrate the relatively thin shielding required for electrons) have a pronounced east-west asymmetry at low altitudes, with the flux from the west much higher than that from the east. By distributing radition shielding mass in response to these anisotropies, spacecraft mass can be reduced, the altitude limits of LEO extended, and the exposure of men and sensitive materials decreased. Geophysical behavior of trapped radiation is reviewed with particular emphasis on the factors responsible for radiation anisotropy. Shielding distribution in response to anisotropic radiation is then explored for consistently oriented spherical and cylindrical spacecraft. The 28.5-deg orbital inclination is considered in detail, with a brief extension of the concepts to other inclinations. These radiation shielding concepts may find near-term application in Space Station design. 21 references

  16. Polarized proton beam for eRHIC

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States); Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Ptitsyn, V. [Brookhaven National Lab. (BNL), Upton, NY (United States); Roser, T. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    RHIC has provided polarized proton collisions from 31 GeV to 255 GeV in the past decade. To preserve polarization through numerous depolarizing resonances through the whole accelerator chain, harmonic orbit correction, partial snakes, horizontal tune jump system and full snakes have been used. In addition, close attentions have been paid to betatron tune control, orbit control and beam line alignment. The polarization of 60% at 255 GeV has been delivered to experiments with 1.8×1011 bunch intensity. For the eRHIC era, the beam brightness has to be maintained to reach the desired luminosity. Since we only have one hadron ring in the eRHIC era, existing spin rotator and snakes can be converted to six snake configuration for one hadron ring. With properly arranged six snakes, the polarization can be maintained at 70% at 250 GeV. This paper summarizes the effort and plan to reach high polarization with small emittance for eRHIC.

  17. Polarized proton beam for eRHIC

    International Nuclear Information System (INIS)

    RHIC has provided polarized proton collisions from 31 GeV to 255 GeV in the past decade. To preserve polarization through numerous depolarizing resonances through the whole accelerator chain, harmonic orbit correction, partial snakes, horizontal tune jump system and full snakes have been used. In addition, close attentions have been paid to betatron tune control, orbit control and beam line alignment. The polarization of 60% at 255 GeV has been delivered to experiments with 1.8@@1011 bunch intensity. For the eRHIC era, the beam brightness has to be maintained to reach the desired luminosity. Since we only have one hadron ring in the eRHIC era, existing spin rotator and snakes can be converted to six snake configuration for one hadron ring. With properly arranged six snakes, the polarization can be maintained at 70% at 250 GeV. This paper summarizes the effort and plan to reach high polarization with small emittance for eRHIC.

  18. Chirality dependent spin polarization of carbon nanotubes

    Science.gov (United States)

    Wang, Jia; Jiang, Wanrun; Wang, Bo; Gao, Yang; Wang, Zhigang; Zhang, Rui-Qin

    2016-02-01

    The spin polarization of carbon nanotubes (CNTs) offers a tunable building block for spintronic devices and is also crucial for realizing carbon-based electronics. However, the effect of chiral CNTs is still unclear. In this paper, we use the density functional theory (DFT) method to investigate the spin polarization of a series of typical finite-length chiral CNTs (9, m). The results show that the spin density of chiral CNTs (9, m) decreases gradually with the increase in m and vanishes altogether when m is larger than or equal to 6. The armchair edge units on both ends of the (9, m) CNTs exhibit a clear inhibition of spin polarization, allowing control of the spin density of (9, m) CNTs by adjusting the number of armchair edge units on the tube end. Furthermore, analysis of the orbitals shows that the spin of the ground state for (9, m) CNTs mainly comes from the contributions of the frontier molecular orbitals (MOs), and the energy gap decreases gradually with the spin density for chiral CNTs. Our work further develops the study of the spin polarization of CNTs and provides a strategy for controlling the spin polarization of functional molecular devices through chiral vector adjustment.

  19. Debris in the geostationary orbit ring, the endless shooting gallery: The necessity for a disposal policy

    Science.gov (United States)

    Suddeth, D. H.

    1985-03-01

    NASA is considering establishing a policy for the limitation of the physical crowding of the geostationary orbit. The proposed policy is intended to address the following issues: (1) deal only with geostationary altitudes; (2) illustrate the unique value and usefulness of the geostationary orbit ring; (3) describe the orbital dynamics as simply as possible; (4) describe the current spacecraft and debris situation; (5) briefly review current industry and agency policies; (6) project future trends of physical crowding with the present nonpolicy; (7) propose solutions that can be implemented in the near future; and (8) use previous work as much as desirable.

  20. Impact of Altitude on Power Output during Cycling Stage Racing.

    Directory of Open Access Journals (Sweden)

    Laura A Garvican-Lewis

    Full Text Available The purpose of this study was to quantify the effects of moderate-high altitude on power output, cadence, speed and heart rate during a multi-day cycling tour.Power output, heart rate, speed and cadence were collected from elite male road cyclists during maximal efforts of 5, 15, 30, 60, 240 and 600 s. The efforts were completed in a laboratory power-profile assessment, and spontaneously during a cycling race simulation near sea-level and an international cycling race at moderate-high altitude. Matched data from the laboratory power-profile and the highest maximal mean power output (MMP and corresponding speed and heart rate recorded during the cycling race simulation and cycling race at moderate-high altitude were compared using paired t-tests. Additionally, all MMP and corresponding speeds and heart rates were binned per 1000 m (3000 m according to the average altitude of each ride. Mixed linear modelling was used to compare cycling performance data from each altitude bin.Power output was similar between the laboratory power-profile and the race simulation, however MMPs for 5-600 s and 15, 60, 240 and 600 s were lower (p ≤ 0.005 during the race at altitude compared with the laboratory power-profile and race simulation, respectively. Furthermore, peak power output and all MMPs were lower (≥ 11.7%, p ≤ 0.001 while racing >3000 m compared with rides completed near sea-level. However, speed associated with MMP 60 and 240 s was greater (p < 0.001 during racing at moderate-high altitude compared with the race simulation near sea-level.A reduction in oxygen availability as altitude increases leads to attenuation of cycling power output during competition. Decrement in cycling power output at altitude does not seem to affect speed which tended to be greater at higher altitudes.