Sample records for sun-synchronous polar orbit

  1. Sun-synchronous satellite orbit determination (United States)

    Ma, Der-Ming; Zhai, Shen-You


    The linearized dynamic equations used for on-board orbit determination of Sun-synchronous satellite are derived. Sun-synchronous orbits are orbits with the secular rate of the right ascension of the ascending node equal to the right ascension rate of the mean sun. Therefore the orbit is no more a closed circle but a tight helix about the Earth. In the paper, instead of treating the orbit as a closed circle, the actual helix orbit is taken as nominal trajectory. The details of the linearized equations of motion for the satellite in the Sun-synchronous orbit are derived. The linearized equations are obtained by perturbing the Keplerian motion with the J2 correction and the effect of sun's attraction being neglected. Combined with the GPS navigation equations, the Kalman filter formulation is given. The particular application considered is the circular Sun-synchronous orbit with the altitude of 800 km and inclination of 98.6°. The numerical example simulated by MATLAB® shows that only the pseudo-range data used in the algorithm still gives acceptable results. Based on the simulation results, we can use the on-board GPS receivers' signal only as an alternative to determine the orbit of Sun-Synchronous satellite and therefore circumvents the need for extensive ground support.

  2. The Apsidal Precession for Low Earth Sun Synchronized Orbits

    Directory of Open Access Journals (Sweden)

    Shkelzen Cakaj


    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.

  3. Artificial Sun synchronous frozen orbit control scheme design based on J2 perturbation

    Institute of Scientific and Technical Information of China (English)

    Gong-Bo Wang; Yun-He Meng; Wei Zheng; Guo-Jian Tang


    Sun synchronous orbit and frozen orbit formed due to J2 perturbation have very strict constraints on orbital parameters,which have restricted the application a lot.In this paper,several control strategies were illustrated to realize Sun synchronous frozen orbit with arbitrary orbital elements using continuous low-thrust.Firstly,according to mean element method,the averaged rate of change of the orbital elements,originating from disturbing constant accelerations over one orbital period,was derived from Gauss' variation of parameters equations.Then,we proposed that binormal acceleration could be used to realize Sun synchronous orbit,and radial or transverse acceleration could be adopted to eliminate the rotation of the argument of the perigee.Finally,amending methods on the control strategies mentioned above were presented to eliminate the residual secular growth.Simulation results showed that the control strategies illustrated in this paper could realize Sun synchronous frozen orbit with arbitrary orbital elements,and can save much more energy than the schemes presented in previous studies,and have no side effect on other orbital parameters' secular motion.

  4. Thermal and orbital analysis of Earth monitoring Sun-synchronous space experiments (United States)

    Killough, Brian D.


    The fundamentals of an Earth monitoring Sun-synchronous orbit are presented. A Sun-synchronous Orbit Analysis Program (SOAP) was developed to calculate orbital parameters for an entire year. The output from this program provides the required input data for the TRASYS thermal radiation computer code, which in turn computes the infrared, solar and Earth albedo heat fluxes incident on a space experiment. Direct incident heat fluxes can be used as input to a generalized thermal analyzer program to size radiators and predict instrument operating temperatures. The SOAP computer code and its application to the thermal analysis methodology presented, should prove useful to the thermal engineer during the design phases of Earth monitoring Sun-synchronous space experiments.

  5. Drift-free solar sail formations in elliptical Sun-synchronous orbits (United States)

    Parsay, Khashayar; Schaub, Hanspeter


    To study the spatial and temporal variations of plasma in the highly dynamic environment of the magnetosphere, multiple spacecraft must fly in a formation. The objective for this study is to investigate the feasibility of solar sail formation flying in the Earth-centered, Sun-synchronous orbit regime. The focus of this effort is to enable formation flying for a group of solar sails that maintain a nominally fixed Sun-pointing attitude during formation flight, solely for the purpose of precessing their orbit apse lines Sun-synchronously. A fixed-attitude solar sail formation is motivated by the difficulties in the simultaneous control of orbit and attitude in flying solar sails. First, the secular rates of the orbital elements resulting from the effects of solar radiation pressure (SRP) are determined using averaging theory for a Sun-pointing attitude sail. These averaged rates are used to analytically derive the first-order necessary conditions for a drift-free solar sail formation in Sun-synchronous orbits, assuming a fixed Sun-pointing orientation for each sail in formation. The validity of the first-order necessary conditions are illustrated by designing quasi-periodic relative motions. Next, nonlinear programming is applied to design truly drift-free two-craft solar sail formations. Lastly, analytic expressions are derived to determine the long-term dynamics and sensitivity of the formation with respect to constant attitude errors, uncertainty in orbital elements, and uncertainty in a sail's characteristic acceleration.

  6. Solution of the flyby problem for large space debris at sun-synchronous orbits (United States)

    Baranov, A. A.; Grishko, D. A.; Medvedevskikh, V. V.; Lapshin, V. V.


    the paper considers the flyby problem related to large space debris (LSD) objects at low earth orbits. The data on the overall dimensions of known last and upper stages of launch vehicles makes it possible to single out five compact groups of such objects from the NORAD catalog in the 500-2000 km altitude interval. The orbits of objects of each group have approximately the same inclinations. The features of the mutual distribution of the orbital planes of LSD objects in the group are shown in a portrait of the evolution of deviations of the right ascension of ascending nodes (RAAN). In the case of the first three groups (inclinations of 71°, 74°, and 81°), the straight lines of relative RAAN deviations of object orbits barely intersect each other. The fourth (83°) and fifth (97°-100°) LSD groups include a considerable number of objects whose orbits are described by straight lines (diagonals), which intersect other lines many times. The use of diagonals makes it possible to significantly reduce the temporal and total characteristic velocity expenditures required for object flybys, but it complicates determination of the flyby sequence. Diagonal solutions can be obtained using elements of graph theory. A solution to the flyby problem is presented for the case of group 5, formed of LSD objects at sun-synchronous orbits.

  7. Shift control method for the local time at descending node based on sun-synchronous orbit satellite

    Institute of Scientific and Technical Information of China (English)

    Yang Yong'an; Feng Zuren; Sun Linyan; Tan Wei


    This article analyzes the shift factors of the descending node local time for sun-synchronous satellites and proposes a shift control method to keep the local time shift within an allowance range. It is found that the satellite orbit design and the orbit injection deviation are the causes for the initial shift velocity, whereas the atmospheric drag and the sun gravitational perturbation produce the shift acceleration. To deal with these shift factors, a shift control method is put forward, through such methods as orbit variation design, orbit altitude, and inclination keeping control. The simulation experiment and practical application have proved the effectiveness of this control method.

  8. 太阳同步圆轨道空间相机瞬态外热流计算%Calculation of transient space heat fluxes for space cameras working in sun-synchronous circle orbit

    Institute of Scientific and Technical Information of China (English)



    In order to obtain accurate,reliable thermal boundary conditions for the thermal design,thermal analysis and thermal tests of space cameras,the transient space heat fluxes of space cameras working in sun-synchronous circle orbits are calculated.The relations of six orbit elements in space orientation of satellites are summarized,and the necessary parameters for the sun-synchronous circle orbit are given.The relative positions between sun vector and orbit,β angles are calculated with STK program for the given sun-synchronous circle orbit,thus the upper temperature orbit and lower temperature orbit are oriented.Based on the theory calculation of space heat fluxes and taking some space cameras working in the given orbit as examples,a Finite Element(FE) calculation model for the space fluxes is constructed.Using IDEAS/TMG module,the transient space heat fluxes of upper temperature orbit and lower temperature orbit are calculated particularly.The transient change curves of solar radiation heat fluxes,earth and solar reflection heat fluxes and the earth and infrared radiation heat fluxes in an orbit period are obtained.The calculation results could be taken as input data of space cameras for thermal analysis and the simulation of space heat fluxes in space environment thermal tests.%为了使空间相机热设计、热分析、热试验具备准确、可靠的热边界条件,对太阳同步圆轨道空间相机的瞬态外热流进行了计算。总结了卫星空间定位的6个轨道根数之间的关系,给出了太阳同步圆轨道空间定位的必要参数。针对某给定太阳同步圆轨道,采用STK软件进行了轨道面与太阳光矢量相对位置关系(β角)的计算,确定了该轨道的高、低温工况位置。归纳了空间外热流的理论计算方法,以外接于卫星平台的空间相机为例,建立了外热流计算模型,采用IDEAS/TMG模块对给定太阳同步圆轨道的高、低温工况轨道周期内瞬态外热流变化

  9. Simulation of Sun Synchronous Orbit Satellite Solar Panel Control%太阳同步轨道卫星帆板对日定向控制与仿真

    Institute of Scientific and Technical Information of China (English)



    航天器所需能源南太阳能帆板提供.针对单翼、单自由度、匀速驱动的太阳同步轨道卫星帆板的对日定向控制问题,研究了轨道偏心率、地球非球形摄动、日月引力、大气阻力、太阳光乐等因素对卫星帆板对日定向精度的影响作用规律,为了提高对日帆板的定位控制精度,提出了在摄动影响下,采用线性拟合的方法,通过合理设置卫星帆板的驱动速度,延长卫星对日定向姿态的稳定时间.仿真结果表明,提出的方法简单易行,能够确保卫星帆板对日定向精度较长时间保持在允许范围内,在提高卫星帆板受晒效率的同时,减少了卫星帆板调整的次数.%Solar panel control problem for a sun synchronous orbit satellite, which has one degree freedom single solar panel droved by a constant velocity to point to the sun, is investigated in this paper. First of all, the rules are found out by simulation to express how the perturbations of orbit eccentricity, nonspherical acceleration, sun and lunar gravity, air drag and sun radiation pressure affect the solar panel attitude. Then, the changing rule of solar panel attitude angle is analyzed with integrated conditions considering all perturbations, and a linear fitting method is obtained. Then, the solar panel theoretic driving velocity is compensated with this method in order to keep solar panel in the optimal position for solarization. Simulation results indicate that the proposed method can keep the panel pointing to the sun for a relative long time, and reduce times to adjust the solar panel attitude.

  10. 太阳同步轨道星敏感器热设计典型工况确定%Typical work states analysis on thermal design of the sun-synchronous orbit star sensors

    Institute of Scientific and Technical Information of China (English)



    以某太阳同步轨道卫星星敏感器为例,阐述了热环境分析、外热流计算、典型工况条件确定以及热试验模拟的全过程。首先,分析了星敏感器所处的内、外部热环境,确定了其温度水平的主要影响因素。其次,进行了星敏感器通光孔到达外热流的计算,确定了典型工况的工况条件。然后,制定了星敏感器热平衡试验外热流的模拟方案,利用闭环程控系统进行外热流加载。最后,依据星敏感器自身特点,提出了热试验外热流的加载策略。典型工况条件的确定合理可行。%The whole process of thermal environment analysis,space heat flux calculation,typical work states analysis and heat flux simulation for thermal test is expatiated for a given star sensors working on sun-synchronous orbit.Firstly,the inner and outer thermal environments of the star sensors were analyzed,and the main influential fac-tors on temperature level were determined.Secondly,heat fluxes that reach the given star sensors were calculated,and the typical work state conditions were obtained.Thirdly,the space heat flux simulation scheme of heat balance test was determined,and closed loop programmable system was applied to load heat flux.Finally,the space heat flux simulation method and tactic of thermal test is proposed according to the characteristics of the star sensors.It proves that the typi-cal work states are rational and feasible.

  11. Estimation of surface insolation using sun-synchronous satellite data (United States)

    Darnell, Wayne L.; Staylor, W. Frank; Gupta, Shashi K.; Denn, Fred M.


    A technique is presented for estimating insolation at the earth's surface using only sun-synchronous satellite data. The technique was tested by comparing the insolation results from year-long satellite data sets with simultaneous ground-measured insolation taken at five continental United States sites. Monthly average insolation values derived from the satellite data showed a standard error of 4.2 W/sq m, or 2.7 percent of the average ground insolation value.

  12. The small satellite NINA-MITA to study galactic and solar cosmic rays in low-altitude polar orbit (United States)

    Furano, G.; Bidoli, V.; Casolino, M.; de Pascale, M. P.; Iannucci, A.; Morselli, A.; Picozza, P.; Reali, E.; Sparvoli, R.; Bakaldin, A.; Galper, A.; Koldashov, M.; Korotkov, M.; Leonov, A.; Mikhailov, V.; Murashov, A.; Voronov, S.; Mazzenga, G.; Ricci, M.; Castellini, G.; Barbiellini, M.; Boezio, M.; Bonvicini, V.; Cirami, R.; Vacchi, A.; Zampa, N.; Ambriola, M.; Bellotti, R.; Cafagna, F.; Ciacio, F.; Circella, M.; de Marzo, C.; Adriani, O.; Papini, P.; Piccardi, S.; Spillantini, P.

    The satellite MITA, carrying on board the scientific payload NINA-2, was launched on July the 15th, 2000 from the cosmodrome of Plesetsk (Russia) with a Cosmos-3M rocket. The satellite and the payload are currently operating within nominal parameters. NINA-2 is the first scientific payload for the technological flight of the Italian small satellite MITA. The detector used in this mission is identical to the one already flying on the Russian satellite Resurs-O1 n.4 in a 840-km sun-synchronous orbit, but makes use of the extensive computer and telemetry capabilities of MITA bus to improve the active data acquisition time. NINA physics objectives are to study cosmic nuclei from hydrogen to iron in the energy range between 10 MeV/n and 1 GeV/n during the years 2000-2003, that is the solar maximum period. The device is capable of charge identification up to iron with isotope sensitivity up to oxigen. The 87.3 degrees, 460 km altitude polar orbit allows investigations of cosmic rays of solar and galactic origin, so to study long and short term solar transient phenomena, and the study of the trapped radiation at higher geomagnetic cutoff.

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

  14. Representativeness of total column water vapour retrievals from instruments on polar orbiting satellites (United States)

    Diedrich, Hannes; Wittchen, Falco; Preusker, René; Fischer, Jürgen


    The remote sensing of total column water vapour (TCWV) from polar orbiting, sun-synchronous satellite spectrometers such as the Medium Resolution Imaging Spectrometer (MERIS) on board of ENVISAT and the Moderate Imaging Spectroradiometer (MODIS) on board of Aqua and Terra enables observations on a high spatial resolution and a high accuracy over land surfaces. The observations serve studies about small-scale variations of water vapour as well as the detection of local and global trends. However, depending on the swath width of the sensor, the temporal sampling is low and the observations of TCWV are limited to cloud-free land scenes. This study quantifies the representativeness of a single TCWV observation at the time of the satellite overpass under cloud-free conditions by investigating the diurnal cycle of TCWV using 9 years of a 2-hourly TCWV data set from global GNSS (Global Navigation Satellite Systems) stations. It turns out that the TCWV observed at 10:30 local time (LT) is generally lower than the daily mean TCWV by 0.65 mm (4 %) on average for cloud-free cases. Averaging over all GNSS stations, the monthly mean TCWV at 10:30 LT, constrained to cases that are cloud-free, is 5 mm (25 %) lower than the monthly mean TCWV at 10:30 LT of all cases. Additionally, the diurnal variability of TCWV is assessed. For the majority of GNSS stations, the amplitude of the averaged diurnal cycle ranges between 1 and 5 % of the daily mean with a minimum between 06:00 and 10:00 LT and maximum between 16:00 and 20:00 LT. However, a high variability of TCWV on an individual day is detected. On average, the TCWV standard deviation is about 15 % regarding the daily mean.

  15. Polar antiferromagnets produced with orbital order. (United States)

    Ogawa, Naoki; Ogimoto, Yasushi; Ida, Yoshiaki; Nomura, Yusuke; Arita, Ryotaro; Miyano, Kenjiro


    Polar states are realized in pseudocubic manganite films fabricated on high-index substrates, in which a Jahn-Teller (JT) distortion remains an active variable. Several types of orbital orders (OOs) were found to develop large optical second harmonics, signaling broken-inversion symmetry distinct from their bulk forms and films on (100) substrates. The observed symmetry lifting and first-principles calculation both indicate that the modified JT q2 mode drives Mn-site off centering, which can be controlled by a magnetic-field-induced phase transition via a coupling of OO and spin orders.

  16. Experimental effects of orbit on polarization loss in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Ranjbar V.; Bai, M.; Huang, H.; Marusic, A.; Ptitsyn, V.; Minty, M.


    We are performing several experiments during the RHIC ramp to better understand the impact of orbit errors on the polarization at our current working point. These will be conducted by exciting specified orbit harmonics during the final two large intrinsic resonance crossing in RHIC during the 250 GeV polarized proton ramp. The resultant polarization response will then be measured.

  17. 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


    @@ 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.

  18. Land Surface Temperature- Comparing Data from Polar Orbiting and Geostationary Satellites (United States)

    Comyn-Platt, E.; Remedios, J. J.; Good, E. J.; Ghent, D.; Saunders, R.


    Land Surface Temperature (LST) is a vital parameter in Earth climate science, driving long-wave radiation exchanges that control the surface energy budget and carbon fluxes, which are important factors in Numerical Weather Prediction (NWP) and the monitoring of climate change. Satellites offer a convenient way to observe LST consistently and regularly over large areas. A comparison between LST retrieved from a Geostationary Instrument, the Spinning Enhanced Visible and InfraRed Imager (SEVIRI), and a Polar Orbiting Instrument, the Advanced Along Track Scanning Radiometer (AATSR) is presented. Both sensors offer differing benefits. AATSR offers superior precision and spatial resolution with global coverage but given its sun-synchronous platform only observes at two local times, ~10am and ~10pm. SEVIRI provides the high-temporal resolution (every 15 minutes) required for observing diurnal variability of surface temperatures but given its geostationary platform has a poorer resolution, 3km at nadir, which declines at higher latitudes. A number of retrieval methods are applied to the raw satellite data: First order coefficient based algorithms provided on an operational basis by the LandSAF (for SEVIRI) and the University of Leicester (for AATSR); Second order coefficient based algorithms put forward by the University of Valencia; and an optimal estimation method using the 1DVar software provided by the NWP SAF. Optimal estimation is an iterative technique based upon inverse theory, thus is very useful for expanding into data assimilation systems. The retrievals are assessed and compared on both a fine scale using in-situ data from recognised validation sites and on a broad scale using two 100x100 regions such that biases can be better understood. Overall, the importance of LST lies in monitoring daily temperature extremes, e.g. for estimating permafrost thawing depth or risk of crop damage due to frost, hence the ideal dataset would use a combination of observations

  19. Estuarine suspended particulate matter concentrations from sun-synchronous satellite remote sensing: tidal and meteorological effects and biases

    NARCIS (Netherlands)

    Eleveld, M.A.; van der Wal, D.; van Kessel, T.


    Optical data from a sun-synchronous satellite were used to investigate how large-scale estuarine suspended particulate matter (SPM) concentrations were affected by tidal and bulk meteorological drivers, and how retrieved SPM is biased by tidal aliasing and sampling under clear sky conditions. Local

  20. Polar-Orbiting Satellite (POES) Images (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...

  1. Hierarchical spin-orbital polarization of a giant Rashba system. (United States)

    Bawden, Lewis; Riley, Jonathan M; Kim, Choong H; Sankar, Raman; Monkman, Eric J; Shai, Daniel E; Wei, Haofei I; Lochocki, Edward B; Wells, Justin W; Meevasana, Worawat; Kim, Timur K; Hoesch, Moritz; Ohtsubo, Yoshiyuki; Le Fèvre, Patrick; Fennie, Craig J; Shen, Kyle M; Chou, Fangcheng; King, Phil D C


    The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of a single initially spin-degenerate band into two branches with opposite spin polarization. Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration. This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

  2. Orbital engineering in symmetry-breaking polar heterostructures. (United States)

    Disa, Ankit S; Kumah, Divine P; Malashevich, Andrei; Chen, Hanghui; Arena, Dario A; Specht, Eliot D; Ismail-Beigi, Sohrab; Walker, F J; Ahn, Charles H


    We experimentally demonstrate a novel approach to substantially modify orbital occupations and symmetries in electronically correlated oxides. In contrast to methods using strain or confinement, this orbital tuning is achieved by exploiting charge transfer and inversion symmetry breaking using atomically layered heterostructures. We illustrate the technique in the LaTiO_{3}-LaNiO_{3}-LaAlO_{3} system; a combination of x-ray absorption spectroscopy and ab initio theory reveals electron transfer and concomitant polar fields, resulting in a ∼50% change in the occupation of Ni d orbitals. This change is sufficiently large to remove the orbital degeneracy of bulk LaNiO_{3} and creates an electronic configuration approaching a single-band Fermi surface. Furthermore, we theoretically show that such three-component heterostructuring is robust and tunable by choice of insulator in the heterostructure, providing a general method for engineering orbital configurations and designing novel electronic systems.

  3. State Geography Using NOAA Polar-Orbiting Satellites. (United States)

    Stadler, Stephen J.


    NOAA polar-orbiting satellites have the capability of providing views of entire states. This article describes the characteristics of data from these satellites, indicates their advantages and disadvantages, and shows how the satellite data can be used in a statewide representation of physical geography for students at the introductory level. (RM)

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

    DEFF Research Database (Denmark)

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


    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...

  5. Imaging Interplanetary CMEs at Radio Frequency From Solar Polar Orbit (United States)

    Wu, Ji; Sun, Weiying; Zheng, Jianhua; Zhang, Cheng; Wang, Chi; Wang, C. B.; Wang, S.

    Coronal mass ejections (CMEs) are violent discharges of plasma and magnetic fields from the Sun's corona. They have come to be recognized as the major driver of physical conditions in the Sun-Earth system. Consequently, the detection of CMEs is important for un-derstanding and ultimately predicting space weather conditions. The Solar Polar Orbit Radio Telescope (SPORT) is a proposed mission to observe the propagation of interplanetary CMEs from solar polar orbit. The main payload (radio telescope) on board SPORT will be an in-terferometric imaging radiometer working at the meter wavelength band, which will follow the propagation of interplanetary CMEs from a distance of a few solar radii to near 1 AU from solar polar orbit. The SPORT spacecraft will also be equipped with a set of optical and in situ measurement instruments such as a EUV solar telescope, a solar wind plasma experiment, a solar wind ion composition instrument, an energetic particle detector, a wave detector, a mag-netometer and an interplanetary radio burst tracker. In this paper, we first describe the current shortage of interplanetary CME observations. Next, the scientific motivation and objectives of SPORT are introduced. We discuss the basic specifications of the main radio telescope of SPORT with reference to the radio emission mechanisms and the radio frequency band to be observed. Finally, we discuss the key technologies of the SPORT mission, including the con-ceptual design of the main telescope, the image retrieval algorithm and the solar polar orbit injection. Other payloads and their respective observation objectives are also briefly discussed. Key words: Interplanetary CMEs; Interferometric imaging; Solar polar orbit; Radiometer.

  6. Polar Air Quality and Climate from a Molniya Orbit (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.


    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

  7. Polarization control of single photon quantum orbital angular momentum states. (United States)

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


    The orbital angular momentum of photons, being defined in an infinite-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 orbital angular momentum of single photons and vice versa. All our schemes exploit a newly developed optical device, the so-called "q-plate", which enables the manipulation of the photon orbital angular momentum driven by the polarization degree of freedom. By stacking several q-plates in a suitable sequence, one can also have access to higher-order angular momentum subspaces. In particular, we demonstrate the control of the orbital angular momentum m degree of freedom within the subspaces of |m| = 2h and |m| = 4h per photon.

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

    CERN Document Server

    Schulz-Baldes, Hermann


    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.

  9. Spin-orbit controlled capacitance of a polar heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Steffen, Kevin; Kopp, Thilo [Center for Electronic Correlations and Magnetism, EP VI, Institute of Physics, University of Augsburg, 86135 Augsburg (Germany); Loder, Florian [Center for Electronic Correlations and Magnetism, EP VI and TP III, Institute of Physics, University of Augsburg, 86135 Augsburg (Germany)


    Oxide heterostructures with polar films display special electronic properties, such as the electronic reconstruction at their internal interfaces with the formation of two-dimensional metallic states. Moreover, the electrical field from the polar layers is inversion-symmetry breaking and may generate a strong Rashba spin-orbit coupling (RSOC) in the interfacial electronic system. We investigate the capacitance of a heterostructure in which a strong RSOC at a metallic interface is controlled by the electric field of a surface electrode. Such a structure is for example given by a LaAlO{sub 3} film on a SrTiO{sub 3} substrate which is gated by a top electrode. We find that due to a strong RSOC the capacitance can be larger than the classical geometric value.

  10. Operational high latitude surface irradiance products from polar orbiting satellites (United States)

    Godøy, Øystein


    It remains a challenge to find an adequate approach for operational estimation of surface incoming short- and longwave irradiance at high latitudes using polar orbiting meteorological satellite data. In this presentation validation results at a number of North Atlantic and Arctic Ocean high latitude stations are presented and discussed. The validation results have revealed that although the method works well and normally fulfil the operational requirements, there is room for improvement. A number of issues that can improve the estimates at high latitudes have been identified. These improvements are partly related to improved cloud classification using satellite data and partly related to improved handling of multiple reflections over bright surfaces (snow and sea ice), especially in broken cloud conditions. Furthermore, the availability of validation sites over open ocean and sea ice is a challenge.

  11. 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


    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...

  12. The National Polar-orbiting Operational Environmental Satellite System (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

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

    DEFF Research Database (Denmark)

    Abu-Samha, Mahmoud; Madsen, Lars Bojer


    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....

  14. Orbital mapping of energy bands and the truncated spin polarization in three-dimensional Rashba semiconductors (United States)

    Liu, Qihang; Zhang, Xiuwen; Waugh, J. A.; Dessau, D. S.; Zunger, Alex


    Associated with spin-orbit coupling (SOC) and inversion symmetry breaking, Rashba spin polarization opens an 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 density functional theory and a multiorbital k .p model a three-dimensional bulk Rashba system (free of complications by surface effects), BiTeI, 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 the 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 textures. This finding suggests a route for designing high-spin-polarization materials by considering the atomic-orbital content.

  15. 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


    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.

  16. Mapping the Space Radiation Environment in LEO Orbit by the SATRAM Timepix Payload On Board the Proba-V Satellite (United States)

    Granja, Carlos; Polansky, Stepan; Sospisil, Stanislav; Owens, Alan; Mellab, Karim


    The compact spacecraft payload SATRAM is operating in LEO orbit since 2013 on board the Proba-V satellite from ESA and provides high-resolution wide-range radiation monitoring of the satellite environment. Equipped with the pixel detector Timepix, the technology demonstration payload determines the composition (particle types) and spectral characterization (stopping power) of the mixed radiation field with quantum imaging sensitivity, charged particle tracking, energy loss and directionality capability. With a polar orbit (sun synchronous, 98° inclination) and altitude of 820 km the space radiation field is continuously sampled over the entire planet every few days. Results are given in the form of spatial- and time- correlated maps of dose rate and particle flux. Comparison is made between quiescent and geomagnetic storm activity periods.

  17. Spin-orbit and tensor mean-field effects on spin-orbit splitting including self-consistent core polarizations

    CERN Document Server

    Zalewski, M; Satula, W; Werner, T R


    A new strategy of fitting the coupling constants of the nuclear energy density functional is proposed, which shifts attention from ground-state bulk to single-particle properties. The latter are analyzed in terms of the bare single-particle energies and mass, shape, and spin core-polarization effects. Fit of the isoscalar spin-orbit and both isoscalar and isovector tensor coupling constants directly to the f5/2-f7/2 spin-orbit splittings in 40Ca, 56Ni, and 48Ca is proposed as a practical realization of this new programme. It is shown that this fit requires drastic changes in the isoscalar spin-orbit strength and the tensor coupling constants as compared to the commonly accepted values but it considerably and systematically improves basic single-particle properties including spin-orbit splittings and magic-gap energies. Impact of these changes on nuclear binding energies is also discussed.


    Institute of Scientific and Technical Information of China (English)



    This paper reports the theoretical calculation of Breit, self-energy, and vacuum polarization corrections in the Ne like system using multi-configuration Dirac-Fock method with the orbital polarization. The relations of these corrections with the atomic number and the orbital symmetries are shown and the calculated correction energies are compared with other calculated results. Our Breit correction energies are all smaller by leV as maximum than the other theoretical Breit correction energies and the differences reveal systematical relation with atomic number. It is found that the configuration interactions have great effect on Breit corrections while the orbital polarization has much smaller effect on Breit corrections. The self-energy and vacuum polarization obtained by our calculation are much different from that in previous literatures for some transitions.

  19. Polarized Molecular Orbital Model Chemistry. II. The PMO Method. (United States)

    Zhang, Peng; Fiedler, Luke; Leverentz, Hannah R; Truhlar, Donald G; Gao, Jiali


    We present a new semiempirical molecular orbital method based on neglect of diatomic differential overlap. This method differs from previous NDDO-based methods in that we include p orbitals on hydrogen atoms to provide a more realistic modeling of polarizability. As in AM1-D and PM3-D, we also include damped dispersion. The formalism is based on the original MNDO one, but in the process of parameterization we make some specific changes to some of the functional forms. The present article is a demonstration of the capability of the new approach, and it presents a successful parametrization for compounds composed only of hydrogen and oxygen atoms, including the important case of water clusters.

  20. Determining the spin-orbit coupling via spin-polarized spectroscopy of magnetic impurities (United States)

    Kaladzhyan, V.; Simon, P.; Bena, C.


    We study the spin-resolved spectral properties of the impurity states associated to the presence of magnetic impurities in two-dimensional as well as one-dimensional systems with Rashba spin-orbit coupling. We focus on Shiba bound states in superconducting materials, as well as on impurity states in metallic systems. Using a combination of a numerical T -matrix approximation and a direct analytical calculation of the bound-state wave function, we compute the local density of states (LDOS) together with its Fourier transform (FT). We find that the FT of the spin-polarized LDOS, a quantity accessible via spin-polarized scanning tunneling microscopy, allows to accurately extract the strength of the spin-orbit coupling. Also, we confirm that the presence of magnetic impurities is strictly necessary for such measurement, and that non-spin-polarized experiments cannot have access to the value of the spin-orbit coupling.

  1. Strong Linear Dichroism in Spin-Polarized Photoemission from Spin-Orbit-Coupled Surface States (United States)

    Bentmann, H.; Maaß, H.; Krasovskii, E. E.; Peixoto, T. R. F.; Seibel, C.; Leandersson, M.; Balasubramanian, T.; Reinert, F.


    A comprehensive understanding of spin-polarized photoemission is crucial for accessing the electronic structure of spin-orbit coupled materials. Yet, the impact of the final state in the photoemission process on the photoelectron spin has been difficult to assess in these systems. We present experiments for the spin-orbit split states in a Bi-Ag surface alloy showing that the alteration of the final state with energy may cause a complete reversal of the photoelectron spin polarization. We explain the effect on the basis of ab initio one-step photoemission theory and describe how it originates from linear dichroism in the angular distribution of photoelectrons. Our analysis shows that the modulated photoelectron spin polarization reflects the intrinsic spin density of the surface state being sampled differently depending on the final state, and it indicates linear dichroism as a natural probe of spin-orbit coupling at surfaces.

  2. 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)


    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.

  3. GPS-derived orbits for the GOCE satellite

    NARCIS (Netherlands)

    Bock, H.; Jäggi, A.; Meyer, U.; Visser, P.N.A.M.; Van den IJssel, J.A.A.; Van Helleputte, T.; Heinze, M.; Hugentobler, U.


    The first ESA (European Space Agency) Earth explorer core mission GOCE (Gravity field and steady-state Ocean Circulation Explorer) was launched on 17 March 2009 into a sun-synchronous dusk–dawn orbit with an exceptionally low initial altitude of about 280 km. The onboard 12-channel dual-frequency GP

  4. Spin-orbit interaction of light and diffraction of polarized beams (United States)

    Bekshaev, Aleksandr Ya


    The edge diffraction of a homogeneously polarized light beam is studied theoretically based on the paraxial optics and Fresnel-Kirchhoff approximation, and the dependence of the diffracted beam pattern of the incident beam polarization is predicted. If the incident beam is circularly polarized, the trajectory of the diffracted beam center of gravity exhibits a small angular deviation from the geometrically expected direction. The deviation is parallel to the screen edge and reverses the sign with the polarization handedness; it is explicitly calculated for the case of a Gaussian incident beam with a plane wavefront. This effect is a manifestation of the spin-orbit interaction of light and can be interpreted as a revelation of the internal spin energy flow immanent in circularly polarized beams. It also exposes the vortex character of the weak longitudinal field component associated with the circularly polarized incident beam.

  5. Spin-to-Orbital Angular Momentum Conversion and Spin-Polarization Filtering in Electron Beams

    CERN Document Server

    Karimi, Ebrahim; Grillo, Vincenzo; Santamato, Enrico; 10.1103/PhysRevLett.108.044801


    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 device, in combination with a suitable diffraction element, can act as a very effective spin-polarization filter. The same approach can also be applied to neutron or atom beams.

  6. Lesions to polar/orbital prefrontal cortex selectively impair reasoning about emotional material. (United States)

    Goel, Vinod; Lam, Elaine; Smith, Kathleen W; Goel, Amit; Raymont, Vanessa; Krueger, Frank; Grafman, Jordan


    While it is widely accepted that lesions to orbital prefrontal cortex lead to emotion related disruptions and poor decision-making, there is very little patient data on this issue involving actual logical reasoning tasks. We tested patients with circumscribed, focal lesions largely confined to polar/orbital prefrontal cortex (BA 10 & 11) (N=17) on logical reasoning tasks involving neutral and emotional content, and compared their performance to that of an age and education-matched normal control group (N=22) and a posterior lesion control group (N=24). Our results revealed a significant group by content interaction driven by a selective impairment in the polar/orbital prefrontal cortex group compared to healthy normal controls and to the parietal patient group, in the emotional content reasoning trials. Subsequent analyses of congruent and incongruent reasoning trials indicated that this impairment was driven by the poor performance of patients with polar/orbital lesions in the incongruent trials. We conclude that the polar/orbital prefrontal cortex plays a critical role in filtering emotionally charged content from the material before it is passed on to the reasoning system in lateral/dorsal regions of prefrontal cortex. Where unfiltered content is passed to the reasoning engine, either as a result of pathology (as in the case of our patients) or as a result of individual differences, reasoning performance suffers.

  7. Designing nonuniform satellite systems for continuous global coverage using equatorial and polar circular orbits (United States)

    Ulybyshev, S. Yu.


    We present a method for designing nonuniform satellite systems for continuous global coverage using a combination of equatorial and near-polar satellite segments in circular orbits. Equations are derived to determine the basic design parameters of the satellite system itself and the conditions of its closure at the joint of near-polar and equatorial segments. We analyze specific features of near-polar and equatorial satellite systems and their advantages and disadvantages compared with existing classes of near-polar phased and kinematically correct satellite systems. We estimate the minimum required number of spacecrafts in satellite systems for a given fold of coverage and present calculated dependences for classes of near-polar phased and equatorial satellite systems with different types of closure. For the class of kinematically correct satellite systems, we analyze the characteristics of systems with a minimum spacecraft flight height and reveal that the number of satellites in the orbital plane depends on the flight height for different folds of coverage. We bring examples of the best near-polar equatorial satellite systems of global coverage for different folds and a class of satellite systems with a fixed number of spacecrafts and orbital planes in them.

  8. Packet routing algorithm for polar orbit LEO satellite constellation network

    Institute of Scientific and Technical Information of China (English)


    Broadband satellite networks are capable of providing global coverage and support various services. The networks constructed by Low Earth Orbit (LEO) satellite constellations have attracted great interests because of their short round-trip delays and wide bandwidths. A challenging problem is to develop a simple and efficient packet routing algorithm for the LEO satellite constellation network. This paper presents a SpiderWeb Topological Network (SWTN) and a distributed packet routing algorithm for the LEO satellite constellation network based on the SWTN. The algorithm gives the minimum propagation delay paths with low computational complexity and requires no routing tables, which is practical for on-board processing. The performance of the algorithm is demonstrated through simulations.


    Energy Technology Data Exchange (ETDEWEB)

    Addison, B. C.; Tinney, C. G.; Wright, D. J. [Exoplanetary Science Group, School of Physics, University of New South Wales, NSW 2052 (Australia); Bayliss, D.; Zhou, G.; Schmidt, B. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Hartman, J. D.; Bakos, G. A., E-mail: [Department of Astrophysical Sciences, Princeton University, NJ 08544 (United States)


    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 {lambda}= -106{sup +19}{sub -13} {sup o}. 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 T{sub eff} > 6250 K and host hot Jupiters in spin-orbit misalignment.

  10. Dynamical Piezoelectric and Magnetopiezoelectric Effects in Polar Metals from Berry Phases and Orbital Moments (United States)

    Varjas, Dániel; Grushin, Adolfo G.; Ilan, Roni; Moore, Joel E.


    The polarization of a material and its response to applied electric and magnetic fields are key solid-state properties with a long history in insulators, although a satisfactory theory required new concepts such as Berry-phase gauge fields. In metals, quantities such as static polarization and the magnetoelectric θ term cease to be well defined. In polar metals, there can be analogous dynamical current responses, which we study in a common theoretical framework. We find that current responses to dynamical strain in polar metals depend on both the first and second Chern forms, related to polarization and magnetoelectricity in insulators as well as the orbital magnetization on the Fermi surface. We provide realistic estimates that predict that the latter contribution will dominate, and we investigate the feasibility of experimental detection of this effect.

  11. Positron-impact ionization of helium in the distorted-wave polarized-orbital method

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, K.K.; Mazumdar, P.S.; Brajamani, S.


    The total cross sections for positron-impact ionization of helium are evaluated by using the distorted-wave polarized-orbital method taking into account the effects of screening and final-channel distortion. The present results are in fair agreement with other elaborate theoretical calculations and experimental results.

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

    DEFF Research Database (Denmark)

    Olsen, Jørgen Lundegaard

    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...

  13. Orbit and Attitude Control of Asymmetric Satellites in Polar Near-Circular Orbit

    Directory of Open Access Journals (Sweden)

    Wei Zhao


    Full Text Available In this paper, the general problem about the orbit and attitude dynamic model is discussed. A feedback linearization control method is introduced for this model. Due to the asymmetric structure, the orbital properties of such satellites are the same as traditional symmetric ones, but the attitude properties are greatly different from the symmetric counterparts. With perturbations accumulate with time, the attitude angles increase periodically with time, but the orbital elements change much slower than the attitude angles. In the attitude dynamic model, chaos could appear. Traditional linear controllers can not compensate enough for asymmetric satellite when the mission is complex, especially in maneuver missions. Thus nonlinear control method is required to solve such problem in large scale. A feedback linearization method, one robust nonlinear control method, is introduced and applied to the asymmetric satellite in this paper. Some simulations are also given and the results show that feedback linearization controller not only stabilizes the system, but also exempt the chaos in the system.

  14. Martian Polar Region Impact Craters: Geometric Properties From Mars Orbiter Laser Altimeter (MOLA) Observations (United States)

    Garvin, J. B.; Sakimoto, S. E. H.; Frawley, J. J.; Matias, A.


    The Mars Orbiter Laser Altimeter (MOLA) instrument onboard the Mars Global Surveyor (MGS) spacecraft has so far observed approximately 100 impact landforms in the north polar latitudes (>60 degrees N) of Mars. Correlation of the topography with Viking Orbiter images indicate that many of these are near-center profiles, and for some of the most northern craters, multiple data passes have been acquired. The northern high latitudes of Mars may contain substantial ground ice and be topped with seasonal frost (largely CO2 with some water), forming each winter. We have analyzed various diagnostic crater topologic parameters for this high-latitude crater population with the objective of characterizing impact features in north polar terrains, and we explore whether there is evidence of interaction with ground ice, frost, dune movement, or other polar processes. We find that there are substantial topographic variations from the characteristics of midlatitude craters in the polar craters that are not readily apparent from prior images. The transition from small simple craters to large complex craters is not well defined, as was observed in the midlatitude MOLA data (transition at 7-8 km). Additionally, there appear to be additional topographic complexities such as anomalously large central structures in many polar latitude impact features. It is not yet clear if these are due to target-induced differences in the formation of the crater or post-formation modifications from polar processes.

  15. Polarized Molecular Orbital Model Chemistry 3. The PMO Method Extended to Organic Chemistry. (United States)

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


    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 results obtained by previous NDDO semiempirical molecular orbital methods, both including and excluding dispersion terms. We also compare the PMO2 properties to SCC-DFTB calculations. Within the class of semiempirical molecular orbital methods, the PMO2 method is found to be especially accurate for polarizabilities, atomization energies, proton transfer energies, noncovalent complexation energies, and chemical reaction barrier heights and to have good across-the-board accuracy for a range of other properties, including dipole moments, partial atomic charges, and molecular geometries.

  16. Polarized Molecular Orbital Model Chemistry 3. The PMO Method Extended to Organic Chemistry (United States)

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


    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 results obtained by previous NDDO semiempirical molecular orbital methods, both including and excluding dispersion terms. We also compare the PMO2 properties to SCC-DFTB calculations. Within the class of semiempirical molecular orbital methods, the PMO2 method is found to be especially accurate for polarizabilities, atomization energies, proton transfer energies, noncovalent complexation energies, and chemical reaction barrier heights and to have good across-the-board accuracy for a range of other properties, including dipole moments, partial atomic charges, and molecular geometries. PMID:23704835

  17. Spinning and orbiting motion of particles in vortex beams with circular or radial polarizations. (United States)

    Li, Manman; Yan, Shaohui; Yao, Baoli; Liang, Yansheng; Zhang, Peng


    Focusing fields of optical vortex (OV) beams with circular or radial polarizations carry both spin angular momentum (SAM) and orbital angular momentum (OAM), and can realize non-axial spinning and orbiting motion of absorptive particles. Using the T-matrix method, we evaluate the optical forces and torques exerted on micro-sized particles induced by the OV beams. Numerical results demonstrate that the particle is trapped on the circle of intensity maxima, and experiences a transverse spin torque along azimuthal direction, a longitudinal spin torque, and an orbital torque, respectively. The direction of spinning motion is not only related to the sign of topological charge of the OV beam, but also to the polarization state. However, the topological charge controls the direction of orbiting motion individually. Optically induced rotations of particles with varying sizes and absorptivity are investigated in OV beams with different topological charges and polarization states. These results may be exploited in practical optical manipulation, especially for optically induced rotations of micro-particles.

  18. Joint Polar Satellite System (JPSS) Micrometeoroid and Orbital Debris (MMOD) Assessment (United States)

    Squire, Michael D.; Cooke, William J.; Williamsen, Joel; Kessler, Donald; Vesely, William E.; Hull, Scott H.; Schonberg, William; Peterson, Glenn E.; Jenkin, Alan B.; Cornford, Steven L.


    The Joint Polar Satellite System (JPSS) Project requested the NASA Engineering and Safety Center (NESC) conduct an independent evaluation of the Micrometeoroid and Orbital Debris (MMOD) models used in the latest JPSS MMOD risk assessment. The principal focus of the assessment was to compare Orbital Debris Engineering Model version 3 (ORDEM 3.0) with the Meteoroid and Space Debris Terrestrial Environment Reference version 2009 (MASTER-2009) and Aerospace Debris Environment Projection Tool (ADEPT) and provide recommendations to the JPSS Project regarding MMOD protection. The outcome of the NESC assessment is contained in this report.

  19. Demonstration on the indexes design of gravity satellite orbit parameters in the low-low satellite-to-satellite tracking mode

    Directory of Open Access Journals (Sweden)

    Liu Xiaogang


    Full Text Available Combining with the exigent demand of the development of satellite gravimetry system in China, aiming at the determination of technical indexes of gravity satellite orbit parameters, on the basis of the numerical experiments and results analysis, the design indexes of gravity satellite orbit height, inter-satellite range and the orbit inclination are analyzed and calculated, and the issues towards twin gravity satellites such as coherence requirement of the orbit semi-major axes, control requirement of the pitch angle and time interval requirement to keep twin satellites formation in mobility are discussed. Results show that the satellite orbit height is 400 km to 500 km, the inter-satellite range is about 220 km, the satellite orbit inclination is between polar orbit and sun-synchronous orbit, the semi-major axes difference of twin satellites orbit is within ±70. 146 m, the pitch angle of twin satellites is about 0.9 degree, and the time interval to keep twin satellites formation in mobility is 7 days to 15 days.

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

    KAUST Repository

    Cheng, Yingchun


    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.

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


    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.

  2. Polarization singularities and orbital angular momentum sidebands from rotational symmetry broken by the Pockels effect. (United States)

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


    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.

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

    Directory of Open Access Journals (Sweden)

    Guenther E.W.


    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.

  4. Application of polar orbiter products in weather forecasting using open source tools and open standards (United States)

    Plieger, Maarten; de Vreede, Ernst


    EUMETSAT disseminates data for a number of polar satellites. At KNMI these data are not fully used for operational weather forecasting mainly because of the irregular coverage and lack of tools for handling these different types of data and products. For weather forecasting there is a lot of interest in the application of products from these polar orbiters. One of the key aspects is the high-resolution of these products, which can complement the information provided by numerical weather forecasts. Another advantage over geostationary satellites is the high coverage at higher latitudes and lack of parallax. Products like the VIIRS day-night band offer many possibilities for this application. This presentation will describe a project that aims to make available a number of products from polar satellites to the forecasting operation. The goal of the project is to enable easy and timely access to polar orbiter products and enable combined presentations of satellite imagery with model data. The system will be able to generate RGB composites (“false colour images”) for operational use. The system will be built using open source components and open standards. Pytroll components are used for data handling, reprojection and derived product generation. For interactive presentation of imagery the browser based ADAGUC WMS viewer component is used. Image generation is done by ADAGUC server components, which provide OGC WMS services. Polar satellite products are stored as true color RGBA data in the NetCDF file format, the satellite swaths are stored as regular grids with their own custom geographical projection. The ADAGUC WMS system is able to reproject, render and combine these data in a webbrowser interactively. Results and lessons learned will be presented at the conference.

  5. Persistent observations of the Arctic from highly elliptical orbits using multispectral, wide field of view day-night imagers (United States)

    Puschell, Jeffery J.; Johnson, David; Miller, Steven


    Persistent satellite observations are essential for monitoring and understanding Earth's environmentally sensitive and rapidly changing Arctic region. Compact wide-field-of-view imagers aboard satellites in Highly Elliptical Orbit (HEO) could stare at the Arctic and collect multispectral, high dynamic range visible and near-infrared imagery with sensitivity similar to that of the Joint Polar Satellite System (JPSS) Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) in sun synchronous polar orbit. These HEO Day/Night Imagers (HDNIs) provide high contrast visible wavelength imagery through the long polar night. Their dynamic range -- extending from the brightest sunlit clouds, ice and snow to reflected moonlight from open water -- enables cloud, ice and sea surface discrimination even under very low light and low thermal contrast conditions. Rapidly refreshed HDNI data results in frequent updates to key environmental products such as cloud imagery and microphysical properties, ice and open water distribution (including real-time maps of where leads are opening and new ice is forming), vector ice motion and vector polar winds from cloud motion. The relatively small size of HDNIs makes them ideal for deployment as a hosted payload or as the primary payload onboard a small satellite.

  6. Anisotropic tunneling between spin-polarized tips and substrate with strong spin-orbit coupling (United States)

    Xie, Yonglong; Jeon, Sangjun; Drozdov, Ilya; Li, Jian; Bernevig, Andrei; Yazdani, Ali


    The ability to measure spin structure on the nanometer scale has attracted substantial interest for a long time. Spin-polarized scanning tunneling microscopy (SP-STM) is an excellent tool for studying fundamental aspect of magnetism at atomic scale. We combine a low temperature STM equipped with a vector magnet and a spin-polarizable tip, to probe superconductors with strong spin-orbit coupling such as Pb, which is emerging as a platform for engineering topological superconductivity. We observe anisotropic tunneling conductance between tip and substrate as a function of the angle of applied in-plane magnetic field. This finding suggests that SP-STM may provide a tool to locally measure spin-orbit coupling, even in non-magnetic substrates.

  7. 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


    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...

  8. Density functional perturbational orbital theory of spin polarization in electronic systems. II. Transition metal dimer complexes. (United States)

    Seo, Dong-Kyun


    We present a theoretical scheme for a semiquantitative analysis of electronic structures of magnetic transition metal dimer complexes within spin density functional theory (DFT). Based on the spin polarization perturbational orbital theory [D.-K. Seo, J. Chem. Phys. 125, 154105 (2006)], explicit spin-dependent expressions of the spin orbital energies and coefficients are derived, which allows to understand how spin orbitals form and change their energies and shapes when two magnetic sites are coupled either ferromagnetically or antiferromagnetically. Upon employment of the concept of magnetic orbitals in the active-electron approximation, a general mathematical formula is obtained for the magnetic coupling constant J from the analytical expression for the electronic energy difference between low-spin broken-symmetry and high-spin states. The origin of the potential exchange and kinetic exchange terms based on the one-electron picture is also elucidated. In addition, we provide a general account of the DFT analysis of the magnetic exchange interactions in compounds for which the active-electron approximation is not appropriate.

  9. Guidance and adaptive-robust attitude & orbit control of a small information satellite (United States)

    Somov, Ye.; Butyrin, S.; Somov, S.; Somova, T.; Testoyedov, N.; Rayevsky, V.; Titov, G.; Yakimov, Ye.; Ovchinnikov, A.; Mathylenko, M.


    We consider a small information satellite which may be placed on an orbit with altitude from 600 up to 1000 km. The satellite attitude and orbit control system contains a strap-down inertial navigation system, cluster of four reaction wheels, magnetic driver and a correcting engine unit with eight electro-reaction engines. We study problems on design of algorithms for spatial guidance, in-flight identification and adaptive-robust control of the satellite motion on sun-synchronous orbit.

  10. Revisiting the proposed planetary system orbiting the eclipsing polar HU Aquarii

    CERN Document Server

    Wittenmyer, Robert A; Marshall, J P; Butters, O W; Tinney, C G


    It has recently been proposed, on the basis of eclipse-timing data, that the eclipsing polar cataclysmic variable HU Aquarii is host to at least two giant planets. However, that result has been called into question based upon the dynamical stability of the proposed planets. In this work, we present a detailed re-analysis of all eclipse timing data available for the HU Aquarii system, making use of standard techniques used to fit orbits to radial-velocity data. We find that the eclipse timings can be used to obtain a two-planet solution that does not require the presence of additional bodies within the system. We then perform a highly detailed dynamical analysis of the proposed planetary system. We show that the improved orbital parameters we have derived correspond to planets that are dynamically unstable on unfeasibly short timescales (of order 10^4 years or less). Given these results, we discuss briefly how the observed signal might in fact be the result of the intrinsic properties of the eclipsing polar, r...

  11. Earth Orbiting Support Systems for commercial low Earth orbit data relay: Assessing architectures through tradespace exploration (United States)

    Palermo, Gianluca; Golkar, Alessandro; Gaudenzi, Paolo


    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.

  12. The ESA Polar Platform: A work-horse for future Earth Observation Missions (United States)

    Reibaldi, G. G.; Cendral, J. L.


    In the frame of the European Space Agency (ESA) Long Term Plan, the Earth Observation Missions play a very important role in contributing to a better knowledge and monitoring of the Earth Environment. Within the range of future Earth Observation missions, the low altitude sun synchronous polar orbit is of special interest because it offers a repeated coverage of the complete surface of the Earth. For this type of mission, a large number of instruments having different technology and application objectives have been developed or are under development in Europe. To cope with those needs, ESA has initiated the development of the Polar Platform as part of its infrastructure to become the work-horse of future Earth Observation Missions in the Polar orbits. This spacecraft bus, through its design modularity, can cope with a wide range of payload complements and instrument requirements so that the future development emphasis in Europe can be placed on payload and observations rather than repeated satellite developments. The Polar Platform design makes maximum use of the SPOT and ERS programmes experience and design in order to reduce development risk and minimize costs. The modular design can cope with different payload accommodation, power and mass requirements as well as different orbit altitudes. The development is well advanced and is now well into the detailed design and development programme, with components and long lead hardware procurement already initiated. The development of the payload complement for the first mission has been initiated in parallel via the POEM-1 Programme. The Polar Platform will also make use of the other ESA's future infrastructure, such as the Ariane 5 Launcher as well as the Data Relay Satellite System in order to ensure global coverage of observations. The launch of the first ESA Polar Platform Mission carrying the POEM-1 Mission is planned for mid-1988. The performance requirements, design and status of development of the Polar Platform

  13. Spin inverter and polarizer curved nanowire driven by Rashba and Dresselhaus spin-orbit interactions (United States)

    Baldo, C.; Villagonzalo, C.


    We propose in theory a curved nanowire structure that can both serve as a spin inverter and a spin polarizer driven by a periodic Rashba spin-orbit coupling (SOC) and a uniform Dresselhaus SOC. The curved section of the U-shaped quasi-one dimensional nanowire with an arc of radius R and circumferential length πR is divided into segments of equal length initially having only its inherent homogeneous Dresselhaus SOC. Then a Rashba-type SOC is applied at every alternating segment. By tuning the Rashba SOC strength and the incident electron energy, this device can flip the spin at the output of an incoming spin-polarized electron. On the other hand, this same device acts as a spin filter for an unpolarized input for which an outgoing electron with a non-zero polarization can be achieved without the application of an external magnetic field. Moreover, the potential modulation caused by the periodic Rashba SOC enables this device to function as an attenuator for a certain range of incident electron energies that can make the probability current density drop to 10-4 of its otherwise magnitude in other regimes.

  14. Detection of a planetary system orbiting the eclipsing polar HU Aqr

    CERN Document Server

    Qian, S -B; Liao, W -P; Li, L -J; Zhu, L -Y; Dai, Z -B; He, J -J; Zhao, E -G; Zhang, J; Li, K


    Using the precise times of mid-egress of the eclipsing polar HU Aqr, we discovered that this polar is orbited by two or more giant planets. The two planets detected so far have masses of at least 5.9 and 4.5\\,M_{Jup}. Their respective distances from the polar are 3.6 AU and 5.4 AU with periods of 6.54 and 11.96 years, respectively. The observed rate of period decrease derived from the downward parabolic change in O-C curve is a factor 15 larger than the value expected for gravitational radiation. This indicates that it may be only a part of a long-period cyclic variation, revealing the presence of one more planet. It is interesting to note that the two detected circumbinary planets follow the Titus-Bode law of solar planets with n=5 and 6. We estimate that another 10 years of observations will reveal the presence of the predicted third planet.

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


    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.

  16. Yaogan 8 And Hope 1 Have Been Put Into Orbit

    Institute of Scientific and Technical Information of China (English)

    Zong He


    @@ ALM-4C launch vehicle lifted off from Taiyuan Satellite Launch Center at 10:31 on December 15, sending the Yaogan 8 satellite and a piggybacked small satellite, Hope 1, into their predetermined sun-synchronous orbit.This is the 121st flight of LM series launch vehicle and the last one of China's space launch missions in 2009. Hope 1 will be used for the country's young people to experience aerospace science and technology.

  17. Spin-orbit-induced longitudinal spin-polarized currents in nonmagnetic solids (United States)

    Wimmer, S.; Seemann, M.; Chadova, K.; Ködderitzsch, D.; Ebert, H.


    For certain nonmagnetic solids with low symmetry the occurrence of spin-polarized longitudinal currents is predicted. These arise due to an interplay of spin-orbit interaction and the particular crystal symmetry. This result is derived using a group-theoretical scheme that allows investigating the symmetry properties of any linear response tensor relevant to the field of spintronics. For the spin conductivity tensor it is shown that only the magnetic Laue group has to be considered in this context. Within the introduced general scheme also the spin Hall and additional related transverse effects emerge without making reference to the two-current model. Numerical studies confirm these findings and demonstrate for (Au1-xPtx)4Sc that the longitudinal spin conductivity may be on the same order of magnitude as the conventional transverse one. The presented formalism only relies on the magnetic space group and therefore is universally applicable to any type of magnetic order.

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

    CERN Document Server

    Laundal, Karl M; Olsen, Nils


    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 $\\textit{Swarm}$ 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 ...

  19. 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;


    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 ca......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...

  20. Orbits

    CERN Document Server

    Xu, Guochang


    This is the first book of the satellite era which describes orbit theory with analytical solutions of the second order with respect to all possible disturbances. Based on such theory, the algorithms of orbits determination are completely revolutionized.

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

    Directory of Open Access Journals (Sweden)

    O. C. Winter


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, T.T., E-mail: [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)


    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.

  3. Orbital angular momentum generation and mode transformation with high efficiency using forked polarization gratings. (United States)

    Li, Yanming; Kim, Jihwan; Escuti, Michael J


    We present a novel optical element that efficiently generates orbital angular momentum (OAM) of light and transforms light between OAM modes based on a polarization grating with a fork-shaped singularity. This forked polarization grating (FPG) is composed of liquid crystalline materials, and can be made either static or switchable with high diffraction efficiency (i.e., 100% theoretically) into a single order. By spatially varying the Pancharatnam-Berry phase, FPGs shape the wavefront and thus control the OAM mode. We demonstrate theoretically and empirically that a charge l(g) FPG creates helical modes with OAM charge ±l(g) when a gaussian beam is input, and more generally, transforms the incident helical mode with OAM charge l(in) into output modes with OAM charge l(in)±l(g). We also show for the first time that this conversion into a single mode can be very efficient (i.e., ∼95% experimentally) at visible wavelengths, and the relative power between the two possible output modes is polarization-controllable from 0% to ∼100%. We developed a fabrication method that substantially improves FPG quality and efficiency over prior work. We also successfully fabricated switchable FPGs, which can be electrically switched between an OAM generating/transforming state and a transmissive state. Our experimental results showed >92% conversion efficiency for both configurations at 633 nm. These holographically fabricated elements are compact (i.e., thin glass plates), lightweight, and easily optimized for nearly any wavelength from ultraviolet to infrared, for a wide range of OAM charge, and for large or small clear apertures. They are ideal elements for enhanced control of OAM, e.g., in optical trapping and high-capacity information.

  4. Deterministic Spin-Orbit Torque Switching of a Perpendicularly Polarized Magnet Using Wedge Shape of the Magnet (United States)

    Bhowmik, Debanjan; Salahuddin, Sayeef


    Spin-orbit torque provides an efficient way to switch magnets for low power memory applications by reducing the current density needed to switch the magnetization. Perpendicularly polarized magnets are preferred for high density data storage applications because of their high thermal stability in scaled dimensions. However, spin-orbit torque cannot switch a perpendicularly polarized magnet deterministically from up to down and down to up in the absence of an external magnetic field because spin-orbit torque alone cannot break the symmetry of the system. This poses a severe challenge to the applicability of spin-orbit torque for memory devices. In this paper, we show through micromagnetic simulations that when spin-orbit torque is applied on a magnet with a wedge shape, the moments of the magnet are aligned in-plane. On removal of the spin-orbit torque the moments deterministically evolve to vertically upward or downward direction because the anisotropy axis of the magnet is tilted away from the vertical direction owing to the wedge shape of the magnet. Thus, spin-orbit torque driven deterministic switching of the magnet in the absence of an external magnetic field is possible.

  5. Suomi National Polar-orbiting Partnership Environmental Data Records: Algorithm Status and Product Maturity (United States)

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


    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.

  6. Monitoring Polar Environmental Change Using FORMOSAT-2 Satellite (United States)

    Huang, C.; Liu, C.; Chang, L.; Wang, S.; Yan, K.; Wu, F.; Wu, A.


    Polar ice loss to the sea currently account for virtually all of the sea-level rise that is not attributable to ocean warming. Huge section of the Ayles Ice Shelf broke off into the Arctic Ocean. Permafrost soil is losing its permanence across the Northern Hemisphere, altering ecosystems and damaging roads and buildings across Alaska, Canada, and Russia. Global warming change the polar environment significantly, especially in recent year. The National Space Organization (NSPO) of Taiwan successfully launched FORMOSAT-2 on 20 May 2004. The orbit is designed to be high-altitude,. Sun-synchronous, and daily-revisit. With high agility in attitude control, FORMOSAT-2 can cover the polar areas up to +/- 90 deg latitude. More than 72 Area of interests in Alaska, Canada, Greenland area and Ice land have imaged periodically in 2006 and 2007. The images have 2m resolution in panchromatic band and 8m in multispectral bands, with size of about 24 x 100 km or large. The ability of FORMOSAT-2 daily revisit has been extended to monitor the change of topography for the glacier and ice shelf daily, weekly and monthly. By using the FORMOSAT-2 stereo pair, we can determine the elevation profile (DEM) across the glacier surface. In this paper, we will present the mapping and topography of Greenland glaciers and ice land including Kangerdlugssuaq Glacier, Greenland, Belcher Glacier, Canada and Ayles ice island. We will demonstrate the DEM extract ability from FORMOSAT-2 polar stereo images( up to 82 deg latitude), and compared with the DEM of the popular SRTM, ASTER which can be acquired to 79 deg latitude. It is expected that FORMOSAT-2 polar images will be continuously collected for years and contribute to the research of global environmental change.

  7. Nonadiabatic tunnel ionization of current-carrying orbitals of prealigned linear molecules in strong circularly polarized laser fields (United States)

    Liu, Kunlong; Barth, Ingo


    We derive the analytical formula of the ratio of the ionization rates of degenerate valence π± orbitals of prealigned linear molecules in strong circularly polarized (CP) laser fields. Interestingly, our theory shows that the ionization ratio for molecular orbitals with opposite azimuthal quantum numbers ±|m | (e.g., π±) is identical to that for atomic orbitals with the same ±|m | (e.g., p±). In general, the electron counter-rotating to the CP laser field tunnels more easily, not only for atoms but also for linear molecules. Our theoretical predictions are then verified by numerically solving the three-dimensional time-dependent Schrödinger equation for the ionization of the prealigned nitric oxide (NO) molecule in strong CP laser fields. Due to the spin-orbital coupling in the electronic ground state of NO and the sensitivity of ionization to the sense of electron rotation, the ionization of NO in CP fields can produce spin-polarized photoelectrons with high controllability of spin polarization up to 100 % .

  8. Long-Term Cryogenic Propellant Storage for the Titan Orbiter Polar Surveyor (TOPS) Mission (United States)

    Mustafi, Shuvo; Francis, John; Li, Xiaoyi; DeLee, Hudson; Purves, Lloyd; Willis, Dewey; Nixon, Conor; Mcguinness, Dan; Riall, Sara; Devine, Matt; hide


    Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LOX) can dramatically enhance NASAs ability to explore the solar system because of 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 technically 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. Employing cryogenic propellants will allow NASA to perform missions to planetary destinations that would not be possible with the use of traditional hypergolic propellants. These new cryogenic storage technologies were implemented in a design study for the Titan Orbiter Polar Surveyor (TOPS) mission, with LH2 and LOX as propellants, and the resulting spacecraft design was able to achieve a 43 launch mass reduction over a TOPS mission, that utilized a conventional 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.

  9. $\\beta$ 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


    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...

  10. Beyond frontier molecular orbital theory: a systematic electron transfer model (ETM) for polar bimolecular organic reactions. (United States)

    Cahill, Katharine J; Johnson, Richard P


    Polar bimolecular reactions often begin as charge-transfer complexes and may proceed with a high degree of electron transfer character. Frontier molecular orbital (FMO) theory is predicated in part on this concept. We have developed an electron transfer model (ETM) in which we systematically transfer one electron between reactants and then use density functional methods to model the resultant radical or radical ion intermediates. Sites of higher reactivity are revealed by a composite spin density map (SDM) of odd electron character on the electron density surface, assuming that a new two-electron bond would occur preferentially at these sites. ETM correctly predicts regio- and stereoselectivity for a broad array of reactions, including Diels-Alder, dipolar and ketene cycloadditions, Birch reduction, many types of nucleophilic additions, and electrophilic addition to aromatic rings and polyenes. Conformational analysis of radical ions is often necessary to predict reaction stereochemistry. The electronic and geometric changes due to one-electron oxidation or reduction parallel the reaction coordinate for electrophilic or nucleophilic addition, respectively. The effect is more dramatic for one-electron reduction.

  11. The Suomi National Polar-Orbiting Partnership (SNPP): Continuing NASA Research and Applications (United States)

    Butler, James; Gleason, James; Jedlovec, Gary; Coronado, Patrick


    The Suomi National Polar-orbiting Partnership (SNPP) satellite was successfully launched into a polar orbit on October 28, 2011 carrying 5 remote sensing instruments designed to provide data to improve weather forecasts and to increase understanding of long-term climate change. SNPP provides operational continuity of satellite-based observations for NOAA's Polar-orbiting Operational Environmental Satellites (POES) and continues the long-term record of climate quality observations established by NASA's Earth Observing System (EOS) satellites. In the 2003 to 2011 pre-launch timeframe, NASA's SNPP Science Team assessed the adequacy of the operational Raw Data Records (RDRs), Sensor Data Records (SDRs), and Environmental Data Records (EDRs) from the SNPP instruments for use in NASA Earth Science research, examined the operational algorithms used to produce those data records, and proposed a path forward for the production of climate quality products from SNPP. In order to perform these tasks, a distributed data system, the NASA Science Data Segment (SDS), ingested RDRs, SDRs, and EDRs from the NOAA Archive and Distribution and Interface Data Processing Segments, ADS and IDPS, respectively. The SDS also obtained operational algorithms for evaluation purposes from the NOAA Government Resource for Algorithm Verification, Independent Testing and Evaluation (GRAVITE). Within the NASA SDS, five Product Evaluation and Test Elements (PEATEs) received, ingested, and stored data and performed NASA's data processing, evaluation, and analysis activities. The distributed nature of this data distribution system was established by physically housing each PEATE within one of five Climate Analysis Research Systems (CARS) located at either at a NASA or a university institution. The CARS were organized around 5 key EDRs directly in support of the following NASA Earth Science focus areas: atmospheric sounding, ocean, land, ozone, and atmospheric composition products. The PEATES provided

  12. 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


    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.

  13. Dual-polarization and dual-mode orbital angular momentum radio vortex beam generated by using reflective metasurface (United States)

    Yu, Shixing; Li, Long; Shi, Guangming


    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.

  14. Toward a Unified View of the Moon's Polar Volatiles from the Lunar Reconnaissance Orbiter (United States)

    Hayne, Paul


    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

  15. Vector Laguerre-Gauss beams with polarization-orbital angular momentum entanglement in a graded-index medium. (United States)

    Petrov, Nikolai I


    It is shown that the vector-vortex Laguerre-Gauss modes with polarization-orbital angular momentum (OAM) entanglement are the vector solutions of the Maxwell equations in a graded-index medium. Focusing of linearly and circularly polarized vortex light beams with nonzero azimuthal and radial indices in a cylindrical graded-index waveguide is investigated. The wave shape variation with distance taking into account the spin-orbit and nonparaxial effects is analyzed. The effect of long-term periodic revival of wave packets due to mode interference in a graded-index cylindrical optical waveguide is demonstrated. High efficiency transfer of a strongly focused spot through an optical waveguide over large distances takes place with a period of revival.

  16. Out-of-plane spin polarization of edge currents in Chern insulator with Rashba spin-orbit interaction (United States)

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


    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.

  17. Seasonal Variation of the Quasi 5 Day Planetary Wave: Causes and Consequences for Polar Mesospheric Cloud Variability in 2007 (United States)


    oscillations. [5] The NASA Aeronomy of Ice in the Mesosphere (AIM) satellite is dedicated to the study of PMCs. AIM was launched into a sun synchronous orbit imaging and particle size experiment on the Aeronomy of Ice in the Mesosphere mission: Instrument concept, design, calibration, and on‐orbit...A.W.Merkel, S.M. Bailey, J. M. Russell III, C. E. Randall, C. Jeppesen, and M. Callan (2009), The cloud imaging and particle size experiment on the Aeronomy of

  18. Spin polarized bound states in the continuum in open Aharonov-Bohm rings with the Rashba spin-orbit interaction (United States)

    Bulgakov, Evgeny N.; Sadreev, Almas F.


    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.

  19. Formation of the Martian Polar Layered Terrains: Quantifying Polar Water Ice and Dust Surface Deposition during Current and Past Orbital Epochs with the NASA Ames GCM (United States)

    Emmett, Jeremy; Murphy, Jim


    Structural and compositional variability in the layering sequences comprising Mars' polar layered terrains (PLT's) is likely explained by orbital-forced climatic variations in the sedimentary cycles of water ice and dust from which they formed [1]. The PLT's therefore contain a direct, extensive record of the recent climate history of Mars encoded in their structure and stratigraphy, but deciphering this record requires understanding the depositional history of their dust and water ice constituents. 3D Mars atmosphere modeling enables direct simulation of atmospheric dynamics, aerosol transport and quantification of surface accumulation for a range of past and present orbital configurations. By quantifying the net yearly polar deposition rates of water ice and dust under Mars' current and past orbital configurations characteristic of the last several millions of years, and integrating these into the present with a time-stepping model, the formation history of the north and south PLT's will be investigated, further constraining their age and composition, and, if reproducible, revealing the processes responsible for prominent features and stratigraphy observed within the deposits. Simulating the formation of the deposits by quantifying net deposition rates during past orbital epochs and integrating these into the present, effectively 'rebuilding' the terrains, could aid in understanding deeper stratigraphic trends, correlating between geographically-separated deposits, explaining the presence and shapes of large-scale polar features, and correlating stratigraphy with geological time. Quantification of the magnitude and geographical distribution of surface aerosol accumulation will build on the work of previous GCM-based investigations [3]. Construction and analysis of hypothetical stratigraphic sequences in the PLT's will draw from previous climate-controlled stratigraphy methodologies [2,4], but will utilize GCM-derived net deposition rates to model orbital

  20. Defense Meteorological Satellite Program (DMSP) - Space Weather Sensors (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Defense Meteorological Satellite Program (DMSP) maintains a constellation of sun-synchronous, near-polar orbiting satellites. The orbital period is 101 minutes...

  1. Asynchronous Polar BY Cam: the Spin-orbital Synchronization and Variation of Accretion Geometry on the 8-year Time Scale (United States)

    Pavlenko, E.; Andreev, M.; Babina, Y.; Malanushenko, V.


    Attempts to estimate the time of a spin-orbital synchronization for asynchronous polar BY Cam have been made many times since 1994 year. However the estimates obtained did not coincide in a wide region, varying from 150 years (Piirola et al. 1994) up to >3500 years (Kafka et al. 2005). We have undertaken photometric observations of BY Cam over 8.1 years (2004 - 2012) and collected an array of data covering 998 hours during 178 nights. Analyzing the data, we have obtained the most reliable estimate of the spin-orbital time synchronization, Ts = 250±20 years, which agrees very well with both Ts = 150- 290 yrs for asynchronous polar V1500 Cyg (Pavlenko & Pelt 1991); (Stockman et al. 1988) and the theoretically predicted Ts < 1000 yr for asynchronous polars as a whole (Andronov 1987). We also found that the accretion stream switches between two dipole magnetic poles and the equatorial magnetic poles during a synodic ˜ 15-d cycle; the number of switching and their phases can be kept during neighbor cycles but varies on a scale of years. Probably this may depend on the phase of the long-term ˜ 1500 day periodicity (Andreev et al. 2012).

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

    Energy Technology Data Exchange (ETDEWEB)

    Disa, Ankit S., E-mail:; 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)


    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.

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

    Institute of Scientific and Technical Information of China (English)

    Ding Xiu-Huan; Zhang Cun-Xi; Wang Rui; Zhou Yun-Qing; Kong Ling-Min


    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.

  4. Kepler-63b: A Giant Planet in a Polar Orbit around a Young Sun-like Star

    CERN Document Server

    Sanchis-Ojeda, Roberto; 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; Everett, Mark E; Fischer, Debra A; Geary, John C; Gilliland, Ronald L; Horch, Elliott P; Howell, Steve B; Latham, David W


    We present the discovery and characterization of a giant planet orbiting the young Sun-like star Kepler-63 (KOI-63, $m_{\\rm Kp} = 11.6$, $T_{\\rm eff} = 5576$ K, $M_\\star = 0.98\\, M_\\odot$). The planet transits every 9.43 days, with apparent depth variations and brightening anomalies caused by large starspots. The planet's radius is $6.1 \\pm 0.2 R_{\\earth}$, 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 we can place a rough upper bound of $120 M_{\\earth}$ (3$\\sigma$). The host star has a high obliquity ($\\psi$ = $104^{\\circ}$), 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-cross...

  5. Jupiter's magnetosphere and aurorae observed by the Juno spacecraft during its first polar orbits

    DEFF Research Database (Denmark)

    Connerney, J. E. P.; Adriani, Alberto; Allegrini, F.


    for Juno's passage over the poles and traverse of Jupiter's hazardous inner radiation belts. Juno's energetic particle and plasma detectors measured electrons precipitating in the polar regions, exciting intense aurorae, observed simultaneously by the ultraviolet and infrared imaging spectrographs. Juno...

  6. Effect of Rashba and Dresselhaus Spin-Orbit Couplings on Electron Spin Polarization in a Hybrid Magnetic-Electric Barrier Nanostructure (United States)

    Yang, Shi-Peng; Lu, Mao-Wang; Huang, Xin-Hong; Tang, Qiang; Zhou, Yong-Long


    A theoretical study has been carried out on the spin-dependent electron transport in a hybrid magnetic-electric barrier nanostructure with both Rashba and Dresselhaus spin-orbit couplings, which can be experimentally realized by depositing a ferromagnetic strip and a Schottky metal strip on top of a semiconductor heterostructure. The spin-orbit coupling-dependent transmission coefficient, conductance, and spin polarization are calculated by solving the Schrödinger equation exactly with the help of the transfer-matrix method. We find that both the magnitude and sign of the electron spin polarization vary strongly with the spin-orbit coupling strength. Thus, the degree of electron spin polarization can be manipulated by properly adjusting the spin-orbit coupling strength, and such a nanosystem can be employed as a controllable spin filter for spintronics applications.

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

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


    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.

  8. HAT-P-7: A Retrograde or Polar Orbit, and a Second Planet

    CERN Document Server

    Winn, Joshua N; Albrecht, Simon; Howard, Andrew W; Marcy, Geoffrey W; Crossfield, Ian J; Holman, Matthew J


    We show that the exoplanet HAT-P-7b has an extremely tilted orbit, with a true angle of at least 86 degrees with respect to its parent star's equatorial plane, and a strong possibility of retrograde motion. We also report evidence for a second planet in a more distant orbit. The evidence for the unparalleled orbit and the additional planet is based on precise observations of the star's apparent radial velocity. The anomalous radial velocity due to rotation (the Rossiter-McLaughlin effect) was found to be a blueshift during the first half of the transit and a redshift during the second half, an inversion of the usual effect, implying that the angle between the sky-projected orbital and stellar angular momentum vectors is 182.5 +/- 9.4 deg. The second planet is implicated by excess radial-velocity variation of the host star over 2 yr. Possibly, the second planet tilted the orbit of the inner planet through a close encounter or the Kozai effect.

  9. HAT-P-7: A Retrograde or Polar Orbit, and a Third Body (United States)

    Winn, Joshua N.; Johnson, John Asher; Albrecht, Simon; Howard, Andrew W.; Marcy, Geoffrey W.; Crossfield, Ian J.; Holman, Matthew J.


    We showed that the exoplanet HAT-P-7b has an extremely tilted orbit, with a true angle of at least 86 degrees with respect to its parent star's equatorial plane, and a strong possibility of retrograde motion. We also report evidence for an additional planet or companion star. The Rossiter-McLaughlin effect was found to be a blueshift during the first half of the transit and a redshift during the second half, an inversion of the usual pattern, implying that the angle between the sky-projected orbital and stellar angular momentum vectors is 182.5 plus or minus 9.4 degrees. The third body is implicated by excess RV variation of the host star over 2 yr. Some possible explanations for the tilted orbit of HAT-P-7b are a close encounter with another planet, the Kozai effect, and resonant capture by an inward-migrating outer planet.

  10. Spin current and polarization in impure two-dimensional electron systems with spin-orbit coupling. (United States)

    Mishchenko, E G; Shytov, A V; Halperin, B I


    We derive the transport equations for two-dimensional electron systems with Rashba spin-orbit interaction and short-range spin-independent disorder. In the limit of slow spatial variations, we obtain coupled diffusion equations for the electron density and spin. Using these equations we calculate electric-field induced spin accumulation and spin current in a finite-size sample for an arbitrary ratio between spin-orbit energy splitting Delta and elastic scattering rate tau(-1). We demonstrate that the spin-Hall conductivity vanishes in an infinite system independent of this ratio.

  11. Benefits of a Geosynchronous Orbit (GEO) Observation Point for Orbit Determination (United States)

    Byrne, R.; Griesmeyer, M.; Schmidt, R.; Shaddix, J.; Bodette, D.


    Determining orbits of unknown objects is a fundamental space situational awareness activity. The U.S. Space Surveillance Network (SSN) currently relies on ground-based radars, optical telescopes, and the Space Based Space Surveillance (SBSS) System. The SBSS system overcomes many of the pitfalls of optical ground-based systems like limited observation times (e.g. weather and time of day) and measurement uncertainty from atmospheric effects. However, the SBSS satellite is in a low earth orbit (630 km, sun synchronous), and must look “up” for GEO objects. This paper analyzes the potential benefits of a GEO observation point for performing metric observations that are combined with ground-based data. Several different scenarios are considered to quantify the reduction in orbit uncertainty from these types of observations. All results are derived using an Extended Kalman filter (EKF) to process the observations. Orbital uncertainties are expressed in terms of the error covariance.

  12. Linear response of heat conductivity of normal-superfluid interface of a polarized Fermi gas to orbital magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahimian, N., E-mail: [Physics Department, Amirkabir University of Technology, Tehran 15914 (Iran, Islamic Republic of); Mehrafarin, M., E-mail: [Physics Department, Amirkabir University of Technology, Tehran 15914 (Iran, Islamic Republic of); Afzali, R., E-mail: [Physics Department, K.N. Toosi University of Technology, Tehran 15418 (Iran, Islamic Republic of)


    Using perturbed Bogoliubov equations, we study the linear response to a weak orbital magnetic field of the heat conductivity of the normal-superfluid interface of a polarized Fermi gas at sufficiently low temperature. We consider the various scattering regions of the BCS regime and analytically obtain the transmission coefficients and the heat conductivity across the interface in an arbitrary weak orbital field. For a definite choice of the field, we consider various values of the scattering length in the BCS range and numerically obtain the allowed values of the average and species-imbalance chemical potentials. Thus, taking Andreev reflection into account, we describe how the heat conductivity is affected by the field and the species imbalance. In particular, we show that the additional heat conductivity due to the orbital field increases with the species imbalance, which is more noticeable at higher temperatures. Our results indicate how the heat conductivity may be controlled, which is relevant to sensitive magnetic field sensors/regulators at the interface.

  13. POLAR-ORBITING ENVIRONMENTAL SATELLITES: Status, Plans, and Future Data Management Challenges (United States)


    tropical storms, volcanic ash,3 and icebergs), and to provide quality assurance for weather prediction models. The following figures present some polar...Source: NOAA. Page 9 GAO-02-684T Figure 6: POES Image of Volcanic Ash Cloud from Mt. Etna, Sicily , in 2001 Source: NOAA. Page 10 GAO-02-684T Figure 7

  14. The case for a modern multiwavelength, polarization-sensitive LIDAR in orbit around Mars (United States)

    Brown, Adrian J.; Michaels, Timothy I.; Byrne, Shane; Sun, Wenbo; Titus, Timothy N.; Colaprete, Anthony; Wolff, Michael J.; Videen, Gorden; Grund, Christian J.


    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. Towards More Consistent Retrievals of Ice Cloud Optical and Microphysical Properties from Polar Orbiting Sensors (United States)

    Baum, B. A.; Heymsfield, A.; Yang, P.


    Differences exist in the ice cloud optical thickness and effective particle size products provided by teams working with data from AVHRR (Advanced Very High Resolution Radiometer), MODIS (MODerate resolution Imaging Spectroradiometer), POLDER (Polarization and Directionality of the Earth Reflectance), Imaging Infrared Radiometer (IIR), and CALIOP (Cloud Aerosol LIdar with Orthogonal Polarization). The issue is in large part due to the assumed ice cloud single-scattering properties that each team uses in their retrievals. To gain insight into this problem, we are developing ice cloud single-scattering properties consistently from solar through far-infrared wavelengths by merging ice cloud microphysical data from in situ measurements with the very latest light scattering calculations for ice habits that include droxtals, solid/hollow columns, plates, solid/hollow bullet rosettes, aggregates of columns, and small/large aggregates of plates. The in-situ measurements are from a variety of field campaigns, including ARM-IOP, CRYSTAL-FACE, ACTIVE, SCOUT, MidCiX, pre-AVE, TC-4, and MACPEX. Among other advances, the light scattering calculations include the full phase matrix (i.e., polarization), incorporate a new treatment of forward scattering, and three levels of surface roughness from smooth to severely roughened. This talk will focus on improvements to our methodology for building both spectral and narrowband bulk scattering optical models appropriate for satellite imagers and hyperspectral infrared sensors. The new models provide a basis for investigating retrieval differences in the products from the sensor teams. We will discuss recent work towards improving the consistency of ice cloud microphysical/optical property retrievals between solar, polarimetric, and infrared retrieval approaches. It will be demonstrated that severely roughened ice particles correspond best in comparisons to polarization measurements. Further discussion will provide insight as to the

  16. 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


    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...... 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...

  17. Spin Polarization Oscillations without Spin Precession: Spin-Orbit Entangled Resonances in Quasi-One-Dimensional Spin Transport

    Directory of Open Access Journals (Sweden)

    D. H. Berman


    Full Text Available Resonant behavior involving spin-orbit entangled states occurs for spin transport along a narrow channel defined in a two-dimensional electron gas, including an apparent rapid relaxation of the spin polarization for special values of the channel width and applied magnetic field (so-called ballistic spin resonance. A fully quantum-mechanical theory for transport using multiple subbands of the one-dimensional system provides the dependence of the spin density on the applied magnetic field and channel width and position along the channel. We show how the spatially nonoscillating part of the spin density vanishes when the Zeeman energy matches the subband energy splittings. The resonance phenomenon persists in the presence of disorder.

  18. Improved orbit predictions using two-line elements

    CERN Document Server

    Levit, Creon


    The density of orbital space debris constitutes an increasing environmental challenge. There are three ways to alleviate the problem: debris mitigation, debris removal and collision avoidance. This paper addresses collision avoidance, by describing a method that contributes to achieving a requisite increase in orbit prediction accuracy. Batch least-squares differential correction is applied to the publicly available two-line element (TLE) catalog of space objects. Using a high-precision numerical propagator, we fit an orbit to state vectors derived from successive TLEs. We then propagate the fitted orbit further forward in time. These predictions are compared to precision ephemeris data derived from the International Laser Ranging Service (ILRS) for several satellites, including objects in the congested sun-synchronous orbital region. The method leads to a predicted range error that increases at a typical rate of 100 meters per day, approximately a 10-fold improvement over TLE's propagated with their associat...

  19. Effects of geometry and linearly polarized cavity photons on charge and spin currents in a quantum ring with spin-orbit interactions (United States)

    Arnold, Thorsten; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar


    We calculate the persistent charge and spin polarization current inside a finite-width quantum ring of realistic geometry as a function of the strength of the Rashba or Dresselhaus spin-orbit interaction. The time evolution in the transient regime of the two-dimensional (2D) quantum ring connected to electrically biased semi-infinite leads is governed by a time-convolutionless non-Markovian generalized master equation. The electrons are correlated via Coulomb interaction. In addition, the ring is embedded in a photon cavity with a single mode of linearly polarized photon field, which is polarized either perpendicular or parallel to the charge transport direction. To analyze carefully the physical effects, we compare to the analytical results of the toy model of a one-dimensional (1D) ring of non-interacting electrons with spin-orbit coupling. We find a pronounced charge current dip associated with many-electron level crossings at the Aharonov-Casher phase ΔΦ = π, which can be disguised by linearly polarized light. Qualitative agreement is found for the spin polarization currents of the 1D and 2D ring. Quantitatively, however, the spin polarization currents are weaker in the more realistic 2D ring, especially for weak spin-orbit interaction, but can be considerably enhanced with the aid of a linearly polarized electromagnetic field. Specific spin polarization current symmetries relating the Dresselhaus spin-orbit interaction case to the Rashba one are found to hold for the 2D ring, which is embedded in the photon cavity.

  20. Multi-angle Imaging SpectroRadiometer (MISR) (United States)

    National Aeronautics and Space Administration — The Multi-angle Imaging SpectroRadiometer (MISR) was successfully launched into sun-synchronous polar orbit aboard Terra, NASA's first Earth Observing System (EOS)...

  1. A Dual Polarization, Active, Microstrip Antenna for an Orbital Imaging Radar System Operating at L-Band (United States)

    Kelly, Kenneth C.; Huang, John


    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.

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

    KAUST Repository

    Wang, Hao


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kortright, Jeffrey B; Kortright, Jeffrey B; Lincoln, Derek M; Edelstein, Ruth Shima; Epstein, Arthur J


    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 molecular orbitals in V[TCNE]x~;;2 associated with backbonding interactions that yield its novel properties.

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


    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.

  5. Charge transfer and polarization for chloride ions bound in ClC transport proteins: natural bond orbital and energy decomposition analyses. (United States)

    Church, Jonathan; Pezeshki, Soroosh; Davis, Christal; Lin, Hai


    ClC transport proteins show a distinct "broken-helix" architecture, in which certain α-helices are oriented with their N-terminal ends pointed toward the binding sites where the chloride ions are held extensively by the backbone amide nitrogen atoms from the helices. To understand the effectiveness of such binding structures, we carried out natural bond orbital analysis and energy decomposition analysis employing truncated active-site model systems for the bound chloride ions along the translocation pore of the EcClC proteins. Our results indicated that the chloride ions are stabilized in such a binding environment by electrostatic, polarization, and charge-transfer interactions with the backbone and a few side chains. Up to ~25% of the formal charges of the chloride ions were found smeared out to the surroundings primarily via charge transfer from the chloride's lone pair n(Cl) orbitals to the protein's antibonding σ*(N-H) or σ*(O-H) orbitals; those σ* orbitals are localized at the polar N-H and O-H bonds in the chloride's first solvation shells formed by the backbone amide groups and the side chains of residues Ser107, Arg147, Glu148, and Tyr445. Polarizations by the chloride ions were dominated by the redistribution of charge densities among the π orbitals and lone pair orbitals of the protein atoms, in particular the atoms of the backbone peptide links and of the side chains of Arg147, Glu148, and Tyr445. The substantial amounts of electron density involved in charge transfer and in polarization were consistent with the large energetic contributions by the two processes revealed by the energy decomposition analysis. The significant polarization and charge-transfer effects may have impacts on the mechanisms and dynamics of the chloride transport by the ClC proteins.

  6. TWINKLE - A Low Earth Orbit Visible and Infrared Exoplanet Spectroscopy Observatory (United States)

    Tessenyi, Marcell; Savini, Giorgio; Tinetti, Giovanna; Tennyson, Jonathan; Dhesi, Mekhi; Joshua, Max


    Twinkle is a space mission designed for visible and near-IR spectroscopic observations of extrasolar planets. Twinkle's highly stable instrument will allow the photometric and spectroscopic observation of a wide range of planetary classes around different types of stars, with a focus on bright sources close to the ecliptic. The planets will be observed through transit and eclipse photometry and spectroscopy, as well as phase curves, eclipse mapping and multiple narrow-band time-series. The targets observed by Twinkle will be composed of known exoplanets mainly discovered by existing and upcoming ground surveys in our galaxy and will also feature new discoveries by space observatories (K2, GAIA, Cheops, TESS).Twinkle is a small satellite with a payload designed to perform high-quality astrophysical observations while adapting to the design of an existing Low Earth Orbit commercial satellite platform. The SSTL-300 bus, to be launched into a low-Earth sun-synchronous polar orbit by 2019, will carry a half-meter class telescope with two instruments (visible and near-IR spectrographs - between 0.4 and 4.5µm - with resolving power R~300 at the lower end of the wavelength scale) using mostly flight proven spacecraft systems designed by Surrey Satellite Technology Ltd and a combination of high TRL instrumentation and a few lower TRL elements built by a consortium of UK institutes.The Twinkle design will enable the observation of the chemical composition and weather of at least 100 exoplanets in the Milky Way, including super-Earths (rocky planets 1-10 times the mass of Earth), Neptunes, sub-Neptunes and gas giants like Jupiter. It will also allow the follow-up photometric observations of 1000+ exoplanets in the visible and infrared, as well as observations of Solar system objects, bright stars and disks.

  7. TWINKLE - A Low Earth Orbit Visible and Infrared Exoplanet Spectroscopy Observatory (United States)

    Tessenyi, M.; Savini, G.; Tinetti, G.; Tennyson, J.; Dhesi, M.; Joshua, M.


    Twinkle is a space mission designed for visible and near-IR spectroscopic observations of extrasolar planets. Twinkle's highly stable instrument will allow the photometric and spectroscopic observation of a wide range of planetary classes around different types of stars, with a focus on bright sources close to the ecliptic. The planets will be observed through transit and eclipse photometry and spectroscopy, as well as phase curves, eclipse mapping and multiple narrow-band time-series. The targets observed by Twinkle will be composed of known exoplanets mainly discovered by existing and upcoming ground surveys in our galaxy and will also feature new discoveries by space observatories (K2, GAIA, Cheops, TESS). Twinkle is a small satellite with a payload designed to perform high-quality astrophysical observations while adapting to the design of an existing Low Earth Orbit commercial satellite platform. The SSTL-300 bus, to be launched into a low-Earth sun-synchronous polar orbit by 2019, will carry a half-meter class telescope with two instruments (visible and near-IR spectrographs - between 0.4 and 4.5μm - with resolving power R˜300 at the lower end of the wavelength scale) using mostly flight proven spacecraft systems designed by Surrey Satellite Technology Ltd and a combination of high TRL instrumentation and a few lower TRL elements built by a consortium of UK institutes. The Twinkle design will enable the observation of the chemical composition and weather of at least 100 exoplanets in the Milky Way, including super-Earths (rocky planets 1-10 times the mass of Earth), Neptunes, sub-Neptunes and gas giants like Jupiter. It will also allow the follow-up photometric observations of 1000+ exoplanets in the visible and infrared, as well as observations of Solar system objects, bright stars and disks.

  8. 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


    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,...

  9. Transfer efficiency of angular momentum in sum-frequency generation and control of its spin and orbital parts by varying polarization and frequency of fundamental beams (United States)

    Perezhogin, I. A.; Grigoriev, K. S.; Potravkin, N. N.; Cherepetskaya, E. B.; Makarov, V. A.


    Considering sum-frequency generation in an isotropic chiral nonlinear medium, we analyze the transfer of the spin angular momentum of fundamental elliptically polarized Gaussian light beams to the signal beam, which appears as the superposition of two Laguerre-Gaussian modes with both spin and orbital angular momentum. Only for the circular polarization of the fundamental radiation is its angular momentum fully transferred to the sum-frequency beam; otherwise, part of it can be transferred to the medium. Its value, as well as the ratio of spin and orbital contributions in the signal beam, depends on the fundamental frequency ratio and the polarization of the incident beams. Higher energy conversion efficiency in sum-frequency generation does not always correspond to higher angular momentum conversion efficiency.

  10. 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


    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 ...

  11. Handbook of satellite orbits from Kepler to GPS

    CERN Document Server

    Capderou, Michel


    Fifty years after Sputnik, artificial satellites have become indispensable monitors in many areas, such as economics, meteorology, telecommunications, navigation and remote sensing. The specific orbits are important for the proper functioning of the satellites. This book discusses the great variety of satellite orbits, both in shape (circular to highly elliptical) and properties (geostationary, Sun-synchronous, etc.). This volume starts with an introduction into geodesy. This is followed by a presentation of the fundamental equations of mechanics to explain and demonstrate the properties for all types of orbits. Numerous examples are included, obtained through IXION software developed by the author. The book also includes an exposition of the historical background that is necessary to help the reader understand the main stages of scientific thought from Kepler to GPS. This book is intended for researchers, teachers and students working in the field of satellite technology. Engineers, geographers and all those...

  12. 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.


    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).

  13. 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


    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.

  14. Maintaining Aura's Orbit Requirements While Performing Orbit Maintenance Maneuvers Containing an Orbit Normal Delta-V Component (United States)

    Johnson, Megan R.; Petersen, Jeremy D.


    The Earth Observing System (EOS) Afternoon Constellation consists of five member missions (GCOM-W1, Aqua, CALIPSO, CloudSat, and Aura), each of which maintain a frozen, sun-synchronous orbit with a 16-day repeating ground track that follows the Worldwide Reference System-2 (WRS-2). Under nominal science operations for Aura, the propulsion system is oriented such that the resultant thrust vector is aligned 13.493 degrees away from the velocity vector along the yaw axis. When performing orbit maintenance maneuvers, the spacecraft performs a yaw slew to align the thrust vector in the appropriate direction. A new Drag Make Up (DMU) maneuver operations scheme has been implemented for Aura alleviating the need for the 13.493 degree yaw slew. The focus of this investigation is to assess the impact that no-slew DMU maneuver operations will have on Aura's Mean Local Time (MLT) which drives the required along track separation between Aura and the constellation members, as well as Aura's frozen orbit properties, eccentricity and argument of perigee. Seven maneuver strategies were analyzed to determine the best operational approach. A mirror pole strategy, with maneuvers alternating at the North and South poles, was implemented operationally to minimize impact to the MLT. Additional analysis determined that the mirror pole strategy could be further modified to include frozen orbit maneuvers and thus maintain both MLT and the frozen orbit properties under noslew operations.

  15. Effects of the Electronic Spin-Orbit Interaction on the Anomalous Asymmetric Scattering of the Spin-Polarized 4He+ Beam with Paramagnetic Target Materials (United States)

    Sakai, Osamu; Suzuki, Taku T.


    The scattering of the electron-spin-polarized 4He+ beam on paramagnetic materials has an anomalously large asymmetric scattering component (ASC) around 5%, which is 104 of that expected from the spin-orbit coupling (SOC) for the potential of the target nucleus. In addition, the ASC of some materials (for example, Au and Pt) changes sign near the scattering angle (θ) of 90° unlike the result predicted by using the potential scattering theory. When the 4He+ approaches the target, virtual electron-transfer (ET) excitations between them occur. The effects of the SOC of electrons (SOEs) on the target atom in the ET intermediate state are studied within the frame of the lowest-order perturbation theory about the ET process. The ASC is caused through the combination of the quantum development of electron orbital states under the SOEs and the He nucleus motion in the intermediate state because the preferred orbital states for the ET depend on the position of the He nucleus. It is shown by a numerical calculation that the present process has the possibility of producing the ASC with a magnitude of around 0.1. In the present process, the ASC shows a θ dependence of cos θ sin θ, which changes sign at θ = 90° when the excited orbital in the ET state has the d-character like the Au and Pt cases.

  16. Comparison of the Defense Meteorological Satellite Program (DMSP) and the NOAA Polar-Orbiting Operational Environmental Satellite (POES) Program, (United States)


    Space Segment..... ..... o. . . . .... . . .. . .. VI-53 VII. ANALYSES OF ORBITAL REQUIREMENTS ........ .o.... VII-l A. Timeliness and Geographic situ platforms, and deter- mination of geographic location of those platforms, such as oceanic buoys, ships automatic stations, aircraft, and...Readout Stations (CRSs). The maximum access period is approximately 15 minutes of each orbit. During this contact time, the C segement must: " Command the

  17. 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


    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.

  18. 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


    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.

  19. 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


    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.

  20. Multi-agent Orbit Design for Visual Perception Enhancement Purpose

    Directory of Open Access Journals (Sweden)

    Hamidreza Nourzadeh


    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.

  1. Orbit determination and orbit control for the Earth Observing System (EOS) AM spacecraft (United States)

    Herberg, Joseph R.; Folta, David C.


    Future NASA Earth Observing System (EOS) Spacecraft will make measurements of the earth's clouds, oceans, atmosphere, land and radiation balance. These EOS Spacecraft will be part of the NASA Mission to Planet Earth. This paper specifically addresses the EOS AM Spacecraft, referred to as 'AM' because it has a sun-synchronous orbit with a 10:30 AM descending node. This paper describes the EOS AM Spacecraft mission orbit requirements, orbit determination, orbit control, and navigation system impact on earth based pointing. The EOS AM Spacecraft will be the first spacecraft to use the TDRSS Onboard Navigation System (TONS) as the primary means of navigation. TONS flight software will process one-way forward Doppler measurements taken during scheduled TDRSS contacts. An extended Kalman filter will estimate spacecraft position, velocity, drag coefficient correction, and ultrastable master oscillator frequency bias and drift. The TONS baseline algorithms, software, and hardware implementation are described in this paper. TONS integration into the EOS AM Spacecraft Guidance, Navigation, and Control (GN&C) System; TONS assisted onboard time maintenance; and the TONS Ground Support System (TGSS) are also addressed.

  2. A mission-oriented orbit design method of remote sensing satellite for region monitoring mission based on evolutionary algorithm (United States)

    Shen, Xin; Zhang, Jing; Yao, Huang


    Remote sensing satellites play an increasingly prominent role in environmental monitoring and disaster rescue. Taking advantage of almost the same sunshine condition to same place and global coverage, most of these satellites are operated on the sun-synchronous orbit. However, it brings some problems inevitably, the most significant one is that the temporal resolution of sun-synchronous orbit satellite can't satisfy the demand of specific region monitoring mission. To overcome the disadvantages, two methods are exploited: the first one is to build satellite constellation which contains multiple sunsynchronous satellites, just like the CHARTER mechanism has done; the second is to design non-predetermined orbit based on the concrete mission demand. An effective method for remote sensing satellite orbit design based on multiobjective evolution algorithm is presented in this paper. Orbit design problem is converted into a multi-objective optimization problem, and a fast and elitist multi-objective genetic algorithm is utilized to solve this problem. Firstly, the demand of the mission is transformed into multiple objective functions, and the six orbit elements of the satellite are taken as genes in design space, then a simulate evolution process is performed. An optimal resolution can be obtained after specified generation via evolution operation (selection, crossover, and mutation). To examine validity of the proposed method, a case study is introduced: Orbit design of an optical satellite for regional disaster monitoring, the mission demand include both minimizing the average revisit time internal of two objectives. The simulation result shows that the solution for this mission obtained by our method meet the demand the users' demand. We can draw a conclusion that the method presented in this paper is efficient for remote sensing orbit design.

  3. Satellite de-orbiting via controlled solar radiation pressure (United States)

    Deienno, Rogerio; Sanchez, Diogo Merguizo; de Almeida Prado, Antonio Fernando Bertachini; Smirnov, Georgi


    The goal of the present research was to study the use of solar radiation pressure to place a satellite in an orbit that makes it to re-enter the atmosphere of the Earth. This phase of the mission is usual, since the orbital space around the Earth is crowded and all satellites have to be discarded after the end of their lifetimes. The technique proposed here is based on a device that can increase and decrease the area-to-mass ratio of the satellite when it is intended to reduce its altitude until a re-entry point is reached. Equations that predict the evolution of the eccentricity and semi-major axis of the orbit of the satellite are derived and can be used to allow the evaluation of the time required for the decay of the satellite. Numerical simulations are made, and they show the time required for the decay as a function of the area-to-mass ratio and the evolution of the most important orbital elements. The results show maps that indicate regions of fast decays as a function of the area-to-mass ratio and the initial inclination of the orbit of the satellite. They also confirmed the applicability of the equations derived here. The numerical results showed the role played by the evection and the Sun-synchronous resonances in the de-orbiting time.

  4. Reliable retrieval of atmospheric and aquatic parameters in coastal and inland environments from polar-orbiting and geostationary platforms: challenges and opportunities (United States)

    Stamnes, Knut; Li, Wei; Lin, Zhenyi; Fan, Yongzhen; Chen, Nan; Gatebe, Charles; Ahn, Jae-Hyun; Kim, Wonkook; Stamnes, Jakob J.


    Simultaneous retrieval of aerosol and surface properties by means of inverse techniques based on a coupled atmosphere-surface radiative transfer model, neural networks, and optimal estimation can yield considerable improvements in retrieval accuracy in complex aquatic environments compared with traditional methods. Remote sensing of such environments represent specific challenges due (i) the complexity of the atmosphere and water inherent optical properties, (ii) unique bidirectional dependencies of the water-leaving radiance, and (iii) the desire to do retrievals for large solar zenith and viewing angles. We will discuss (a) how challenges related to atmospheric gaseous absorption, absorbing aerosols, and turbid waters can be addressed by using a coupled atmosphere-surface radiative transfer (forward) model in the retrieval process, (b) how the need to correct for bidirectional effects can be accommodated in a systematic and reliable manner, (c) how polarization information can be utilized, (d) how the curvature of the atmosphere can be taken into account, and (e) how neural networks and optimal estimation can be used to obtain fast yet accurate retrievals. Special emphasis will be placed on how information from existing and future sensors deployed on polar-orbiting and geostationary platforms can be obtained in a reliable and accurate manner. The need to provide uncertainty assessments and error budgets will also be discussed.

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


    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].

  6. Maintaining Aura's Orbit Requirements Under New Maneuver Operations (United States)

    Johnson, Megan; Petersen, Jeremy D.


    The Earth Observing System (EOS) Afternoon Constellation consists of five member missions (GCOM-W1, Aqua, CALIPSO, CloudSat, and Aura), each of which maintain a frozen, sun-synchronous orbit with a 16-day repeating ground track that follows the Worldwide Reference System-2 (WRS-2). Under nominal science operations for Aura, the propulsion system is oriented such that the resultant thrust vector is aligned 13.493 degrees away from the velocity vector along the yaw axis. When performing orbit maintenance maneuvers, the spacecraft performs a yaw slew to align the thrust vector in the appropriate direction. A new Drag Make Up (DMU) maneuver operations scheme has been implemented for Aura alleviating the need for the 13.493 degree yaw slew. The focus of this investigation is to assess the impact that no-slew DMU maneuver operations will have on Auras Mean Local Time (MLT) which drives the required along track separation between Aura and the constellation members, as well as Auras frozen orbit properties, eccentricity and argument of perigee. Seven maneuver strategies were analyzed to determine the best operational approach. A mirror pole strategy, with maneuvers alternating at the North and South poles, was implemented operationally to minimize impact to the MLT. Additional analysis determined that the mirror pole strategy could be further modified to include frozen orbit maneuvers and thus maintain both MLT and the frozen orbit properties under no-slew operations

  7. Spin-helical Dirac states in graphene induced by polar-substrate surfaces with giant spin-orbit interaction: a new platform for spintronics. (United States)

    Eremeev, S V; Nechaev, I A; Echenique, P M; Chulkov, E V


    Spintronics, or spin electronics, is aimed at efficient control and manipulation of spin degrees of freedom in electron systems. To comply with demands of nowaday spintronics, the studies of electron systems hosting giant spin-orbit-split electron states have become one of the most important problems providing us with a basis for desirable spintronics devices. In construction of such devices, it is also tempting to involve graphene, which has attracted great attention because of its unique and remarkable electronic properties and was recognized as a viable replacement for silicon in electronics. In this case, a challenging goal is to lift spin degeneracy of graphene Dirac states. Here, we propose a novel pathway to achieve this goal by means of coupling of graphene and polar-substrate surface states with giant Rashba-type spin-splitting. We theoretically demonstrate it by constructing the graphene@BiTeCl system, which appears to possess spin-helical graphene Dirac states caused by the strong interaction of Dirac and Rashba electrons. We anticipate that our findings will stimulate rapid growth in theoretical and experimental investigations of graphene Dirac states with real spin-momentum locking, which can revolutionize the graphene spintronics and become a reliable base for prospective spintronics applications.

  8. 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


    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.

  9. Improving satellite vulnerability assessment to untrackable orbital debris (United States)

    Welty, Nathan; Schaefer, Frank; Rudolph, Martin; Destefanis, Roberto; Grassi, Lilith


    The projected growth in the untrackable orbital debris population will place an increased emphasis on satellite vulnerability assessments during both design and mission operations. This study presents an enhanced method for assessing satellite vulnerability to untrackable orbital debris that expands on traditional practices. By looking beyond structural penetration of the spacecraft, the method predicts the survivability of individual components and the associated degradation of system functionality resulting from untrackable debris impacts. A new risk assessment tool, the Particle Impact Risk and Vulnerability Assessment Tool (PIRAT), has been developed based on this method and is also presented here. It interfaces with both the NASA ORDEM2000 and ESA MASTER-2009 debris models and has been validated against the benchmark test cases from the Inter-Agency Space Debris Coordination Committee (IADC). This study concludes with an example vulnerability assessment using PIRAT for a generic Earth observation satellite in a Sun-synchronous low-Earth orbit. The results illustrate the additional insight provided by this method that can be used to improve the robustness of future satellite designs and mitigate the overall mission risk posed by untrackable orbital debris.

  10. PoPSat: The Polar Precipitation Satellite Mission (United States)

    Binder, Matthias J.; Agten, Dries; Arago-Higueras, Nadia; Borderies, Mary; Diaz-Schümmer, Carlos; Jamali, Maryam; Jimenez-Lluva, David; Kiefer, Joshua; Larsson, Anna; Lopez-Gilabert, Lola; Mione, Michele; Mould, Toby JD; Pavesi, Sara; Roth, Georg; Tomicic, Maja


    The terrestrial water cycle is one of many unique regulatory systems on planet Earth. It is directly responsible for sustaining biological life on land and human populations by ensuring sustained crop yields. However, this delicate balanced system continues to be influenced significantly by a changing climate, which has had drastic impacts particularly on the polar regions. Precipitation is a key process in the weather and climate system, due to its storage, transport and release of latent heat in the atmosphere. It has been extensively investigated in low latitudes, in which detailed models have been established for weather prediction. However, a gap has been left in higher latitudes above 65°, which show the strongest response to climate changes and where increasing precipitations have been foreseen in the future. In order to establish a global perspective of atmospheric processes, space observation of high-latitude areas is crucial to produce globally consistent data. The increasing demand for those data has driven a critical need to devise a mission which fills the gaps in current climate models. The authors propose the Polar Precipitation Satellite (PoPSat), an innovative satellite mission to provide enhanced observation of light and medium precipitation, focusing on snowfall and light rain in high latitudes. PoPSat is the first mission aimed to provide high resolution 3D structural information about snow and light precipitation systems and cloud structure in the covered areas. The satellite is equipped with a dual band (Ka and W band) phased-array radar. These antennas provide a horizontal resolution of 2 km and 4 km respectively which will exceed all other observations made to date at high-latitudes, while providing the additional capability to monitor snowfall. The data gathered will be compatible and complementary with measurements made during previous missions. PoPSat has been designed to fly on a sun-synchronous, dawn-dusk orbit at 460 km. This orbit

  11. Towards high temporal and moderate spatial resolutions in the remote sensing retrieval of evapotranspiration by combining geostationary and polar orbit satellite data (United States)

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


    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) ( 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

  12. Cloud-based opportunities in scientific computing: insights from processing Suomi National Polar-Orbiting Partnership (S-NPP) Direct Broadcast data (United States)

    Evans, J. D.; Hao, W.; Chettri, S.


    The cloud is proving to be a uniquely promising platform for scientific computing. Our experience with processing satellite data using Amazon Web Services highlights several opportunities for enhanced performance, flexibility, and cost effectiveness in the cloud relative to traditional computing -- for example: - Direct readout from a polar-orbiting satellite such as the Suomi National Polar-Orbiting Partnership (S-NPP) requires bursts of processing a few times a day, separated by quiet periods when the satellite is out of receiving range. In the cloud, by starting and stopping virtual machines in minutes, we can marshal significant computing resources quickly when needed, but not pay for them when not needed. To take advantage of this capability, we are automating a data-driven approach to the management of cloud computing resources, in which new data availability triggers the creation of new virtual machines (of variable size and processing power) which last only until the processing workflow is complete. - 'Spot instances' are virtual machines that run as long as one's asking price is higher than the provider's variable spot price. Spot instances can greatly reduce the cost of computing -- for software systems that are engineered to withstand unpredictable interruptions in service (as occurs when a spot price exceeds the asking price). We are implementing an approach to workflow management that allows data processing workflows to resume with minimal delays after temporary spot price spikes. This will allow systems to take full advantage of variably-priced 'utility computing.' - Thanks to virtual machine images, we can easily launch multiple, identical machines differentiated only by 'user data' containing individualized instructions (e.g., to fetch particular datasets or to perform certain workflows or algorithms) This is particularly useful when (as is the case with S-NPP data) we need to launch many very similar machines to process an unpredictable number of

  13. High-precision repeat-groundtrack orbit design and maintenance for Earth observation missions (United States)

    He, Yanchao; Xu, Ming; Jia, Xianghua; Armellin, Roberto


    The focus of this paper is the design and station keeping of repeat-groundtrack orbits for Sun-synchronous satellites. A method to compute the semimajor axis of the orbit is presented together with a station-keeping strategy to compensate for the perturbation due to the atmospheric drag. The results show that the nodal period converges gradually with the increase of the order used in the zonal perturbations up to J_{15} . A differential correction algorithm is performed to obtain the nominal semimajor axis of the reference orbit from the inputs of the desired nodal period, eccentricity, inclination and argument of perigee. To keep the satellite in the proximity of the repeat-groundtrack condition, a practical orbit maintenance strategy is proposed in the presence of errors in the orbital measurements and control, as well as in the estimation of the semimajor axis decay rate. The performance of the maintenance strategy is assessed via the Monte Carlo simulation and the validation in a high fidelity model. Numerical simulations substantiate the validity of proposed mean-elements-based orbit maintenance strategy for repeat-groundtrack orbits.

  14. High-precision repeat-groundtrack orbit design and maintenance for Earth observation missions (United States)

    He, Yanchao; Xu, Ming; Jia, Xianghua; Armellin, Roberto


    The focus of this paper is the design and station keeping of repeat-groundtrack orbits for Sun-synchronous satellites. A method to compute the semimajor axis of the orbit is presented together with a station-keeping strategy to compensate for the perturbation due to the atmospheric drag. The results show that the nodal period converges gradually with the increase of the order used in the zonal perturbations up to J_{15}. A differential correction algorithm is performed to obtain the nominal semimajor axis of the reference orbit from the inputs of the desired nodal period, eccentricity, inclination and argument of perigee. To keep the satellite in the proximity of the repeat-groundtrack condition, a practical orbit maintenance strategy is proposed in the presence of errors in the orbital measurements and control, as well as in the estimation of the semimajor axis decay rate. The performance of the maintenance strategy is assessed via the Monte Carlo simulation and the validation in a high fidelity model. Numerical simulations substantiate the validity of proposed mean-elements-based orbit maintenance strategy for repeat-groundtrack orbits.

  15. 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


    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.

  16. Effect of perturbations on debris-to-debris orbital transfers: A quantitative analysis (United States)

    Kumar, Kartik; Hekma, Enne; Agrawal, Abhishek; Topputo, Francesco


    We investigated the applicability of the Lambert solver (Izzo, 2014) for preliminary design of Multi-Target Active Debris Removal missions. Firstly, we computed ≈25 million debris-to-debris transfers using the Lambert solver for selected sets of debris objects in Low Earth Orbit, Geostationary Transfer Orbit, and Geosynchronous Orbit. Subsequently, we propagated the departure states of the Lambert transfers below selected ΔV cut-offs using the SGP4/SDP4 propagator (Vallado et al., 2006). We recorded the arrival position and velocity error vectors incurred by neglecting perturbations and analyzed the results for each orbital regime. Our results indicate that perturbations can play a significant role in determining the feasibility of debris-to-debris transfers. By using the Lambert solver and neglecting perturbations, the errors in the arrival position and velocity for individual legs can be large. The largest errors were obtained for transfers between debris objects in Sun-Synchronous Orbit (O (100) km error in magnitude of position vector and O (0.1) km/s error in magnitude of velocity vector). Hence, solely employing the Lambert solver to rank transfer legs could lead to incorrect choices for sequencing of multi-target trajectories. This is particularly relevant for transfers in Low Earth Orbit, where the effects of perturbations are the strongest.

  17. Family of Orbiters (United States)


    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.

  18. WFPC2 Polarization Calibration (United States)

    Biretta, J.; McMaster, M.


    We derive a detailed calibration for WFPC2 polarization data which is accurate to about 1.5%. We begin by computing polarizer flats, and show how they are applied to data. A physical model for the polarization effects of the WFPC2 optics is then created using Mueller matricies. This model includes corrections for the instrumental polarization (diattenuation and phase retardance) of the pick-off mirror, as well as the high cross-polarization transmission of the polarizer filter. We compare this model against the on-orbit observations of polarization calibrators, and show it predicts relative counts in the different polarizer/aperture settings to 1.5% RMS accuracy. We then show how this model can be used to calibrate GO data, and present two WWW tools which allow observers to easily calibrate their data. Detailed examples are given illustrationg the calibration and display of WFPC2 polarization data. In closing we describe future plans and possible improvements.

  19. 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


    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 o...

  20. Spin-helical Dirac states in graphene induced by polar-substrate surfaces with giant spin-orbit interaction: a new platform for spintronics


    Eremeev, S. V.; I. A. Nechaev; Echenique, P. M.; Chulkov, E.V.


    Spintronics, or spin electronics, is aimed at efficient control and manipulation of spin degrees of freedom in electron systems. To comply with demands of nowaday spintronics, the studies of electron systems hosting giant spin-orbit-split electron states have become one of the most important problems providing us with a basis for desirable spintronics devices. In construction of such devices, it is also tempting to involve graphene, which has attracted great attention because of its unique an...

  1. Polar Diving (United States)


    3 July 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers exposed by erosion in a trough within the north polar residual cap of Mars, diving beneath a younger covering of polar materials. The layers have, since the Mariner 9 mission in 1972, been interpreted to be composed of a combination of dust and ice in unknown proportions. In this scene, a layer of solid carbon dioxide, which was deposited during the previous autumn and winter, blankets the trough as well as the adjacent terrain. Throughout northern spring, the carbon dioxide will be removed; by summer, the layers will be frost-free. Location near: 81.4oN, 352.2oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Spring

  2. Orbital cellulitis (United States)

    ... hemolytic streptococci may also cause orbital cellulitis. Orbital cellulitis infections in children may get worse very quickly and ... in the space around the eye. An orbital cellulitis infection can get worse very quickly. A person with ...

  3. Overview of calibration and validation activities for the EUMETSAT polar system: second generation (EPS-SG) visible/infrared imager (METimage) (United States)

    Phillips, P.; Bonsignori, R.; Schlüssel, P.; Schmülling, F.; Spezzi, L.; Watts, P.; Zerfowski, I.


    The EPS-SG Visible/Infrared Imaging (VII) mission is dedicated to supporting the optical imagery user needs for Numerical Weather Prediction (NWP), Nowcasting (NWC) and climate in the timeframe beyond 2020. The VII mission is fulfilled by the METimage instrument, developed by the German Space Agency (DLR) and funded by the German government and EUMETSAT. Following on from an important list of predecessors such as the Advanced Very High Resolution Radiometer (AVHRR) and the Moderate resolution Imaging Spectro-radiometer (MODIS), METimage will fly in the mid-morning orbit of the Joint Polar System, whilst the early-afternoon orbits are served by the JPSS (U.S. Joint Polar Satellite System) Visible Infrared Imager Radiometer Suite (VIIRS). METimage itself is a cross-purpose medium resolution, multi-spectral optical imager, measuring the optical spectrum of radiation emitted and reflected by the Earth from a low-altitude sun synchronous orbit over a minimum swath width of 2700 km. The top of the atmosphere outgoing radiance will be sampled every 500 m (at nadir) with measurements made in 20 spectral channels ranging from 443 nm in the visible up to 13.345 μm in the thermal infrared. The three major objectives of the EPS-SG METimage calibration and validation activities are: • Verification of the instrument performances through continuous in-flight calibration and characterisation, including monitoring of long term stability. • Provision of validated level 1 and level 2 METimage products. • Revision of product processing facilities, i.e. algorithms and auxiliary data sets, to assure that products conform with user requirements, and then, if possible, exceed user expectations. This paper will describe the overall Calibration and Validation (Cal/Val) logic and the methods adopted to ensure that the METimage data products meet performance specifications for the lifetime of the mission. Such methods include inter-comparisons with other missions through simultaneous

  4. 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.


    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

  5. Measurement of particle directions in low earth orbit with a Timepix (United States)

    Gohl, St.; Bergmann, B.; Granja, C.; Owens, A.; Pichotka, M.; Polansky, S.; Pospisil, S.


    In Low Earth Orbit (LEO) in space electronic equipment aboard satellites and space crews are exposed to high ionizing radiation levels. To reduce radiation damage and the exposure of astronauts, to improve shielding and to assess dose levels, it is valuable to know the composition of the radiation fields and particle directions. The presented measurements are carried out with the Space Application of Timepix Radiation Monitor (SATRAM). There, a Timepix detector (300 μm thick silicon sensor, pixel pitch 55 μm, 256 × 256 pixels) is attached to the Proba-V, an earth observing satellite of the European Space Agency (ESA). The Timepix detector's capability was used to determine the directions of energetic charged particles and their corresponding stopping powers. Data are continuously taken at an altitude of 820 km on a sun-synchronous orbit. The particles pitch angles with respect to the sensor layer were measured and converted to an Earth Centred Earth Fixed (ECEF) coordinate system. Deviations from an isotropic field are extracted by normalization of the observed angular distributions by a Geant4 Monte Carlo simulation —taking the systematics of the reconstruction algorithm and the pixelation into account.

  6. 极轨道LEO卫星通信系统区分服务路由机制%Differentiated service-oriented routing mechanisms for polar-orbit LEO satellite communication systems

    Institute of Scientific and Technical Information of China (English)

    饶元; 元昌安; 朱军; 傅雷扬; 邵星; 王汝传


    针对极轨道星座低轨(LEO,Low Earth Orbit)卫星通信系统路由存在的切换处理和差异化服务能力不足问题,提出了一种分布式与源路由相结合的区分服务路由机制.利用网络拓扑变化特征、地面热点区域模型与星际链路拥塞状态等局部信息分布式转发尽力交付业务,在此基础上综合星地、星际链路可用时长和业务特点设计源路由算法转发时延、带宽敏感业务.仿真结果表明,该机制的切换处理与区分服务能力有明显提升,信令开销、端到端时延、丢包率和时延抖动优于传统方法.%Exiting routing schemes for Polar-orbit LEO ( Low Earth Orbit) satellite communication systems have some drawbacks in handover handling and differentiated service. Novel differentiated service-oriented routing mechanisms are proposed combining distributed routing with source routing method. Best-effort delivery traffic is distributedly forwarded considering topological change characteristic, hot spot model on the earth's surface and inter-satellite-link congestion. Moreover, delay-and bandwidth-sensitivity traffic are transmitted employing source routing based on traffic characteristic and the duration of user-data-link and inter-satellite-link. Simulation results demonstrate that the proposed mechanisms perform better in terms of handling handover and providing differentiated service, and have lower signaling overhead, end-to-end delay, packet loss ratio and delay jitter when compared to other routing schemes.

  7. The Eccentric Behavior of Nearly Frozen Orbits (United States)

    Sweetser, Theodore H.; Vincent, Mark A.


    Frozen orbits are orbits which have only short-period changes in their mean eccentricity and argument of periapse, so that they basically keep a fixed orientation within their plane of motion. Nearly frozen orbits are those whose eccentricity and argument of periapse have values close to those of a frozen orbit. We call them "nearly" frozen because their eccentricity vector (a vector whose polar coordinates are eccentricity and argument of periapse) will stay within a bounded distance from the frozen orbit eccentricity vector, circulating around it over time. For highly inclined orbits around the Earth, this distance is effectively constant over time. Furthermore, frozen orbit eccentricity values are low enough that these orbits are essentially eccentric (i.e., off center) circles, so that nearly frozen orbits around Earth are bounded above and below by frozen orbits.

  8. Model improvements and validation of TerraSAR-X precise orbit determination (United States)

    Hackel, S.; Montenbruck, O.; Steigenberger, P.; Balss, U.; Gisinger, C.; Eineder, M.


    The radar imaging satellite mission TerraSAR-X requires precisely determined satellite orbits for validating geodetic remote sensing techniques. Since the achieved quality of the operationally derived, reduced-dynamic (RD) orbit solutions limits the capabilities of the synthetic aperture radar (SAR) validation, an effort is made to improve the estimated orbit solutions. This paper discusses the benefits of refined dynamical models on orbit accuracy as well as estimated empirical accelerations and compares different dynamic models in a RD orbit determination. Modeling aspects discussed in the paper include the use of a macro-model for drag and radiation pressure computation, the use of high-quality atmospheric density and wind models as well as the benefit of high-fidelity gravity and ocean tide models. The Sun-synchronous dusk-dawn orbit geometry of TerraSAR-X results in a particular high correlation of solar radiation pressure modeling and estimated normal-direction positions. Furthermore, this mission offers a unique suite of independent sensors for orbit validation. Several parameters serve as quality indicators for the estimated satellite orbit solutions. These include the magnitude of the estimated empirical accelerations, satellite laser ranging (SLR) residuals, and SLR-based orbit corrections. Moreover, the radargrammetric distance measurements of the SAR instrument are selected for assessing the quality of the orbit solutions and compared to the SLR analysis. The use of high-fidelity satellite dynamics models in the RD approach is shown to clearly improve the orbit quality compared to simplified models and loosely constrained empirical accelerations. The estimated empirical accelerations are substantially reduced by 30% in tangential direction when working with the refined dynamical models. Likewise the SLR residuals are reduced from -3 ± 17 to 2 ± 13 mm, and the SLR-derived normal-direction position corrections are reduced from 15 to 6 mm, obtained from

  9. Improved Space Object Orbit Determination Using CMOS Detectors (United States)

    Schildknecht, T.; Peltonen, J.; Sännti, T.; Silha, J.; Flohrer, T.


    a sensor in a sun-synchronous LEO orbit, always pointing in the anti-sun direction to achieve optimum illumination conditions for small LEO debris, was simulated. For the space-based scenario the simulations showed a 20 130 % improvement of the accuracy of all orbital parameters when varying the frame rate from 1/3 fps, which is the fastest rate for a typical CCD detector, to 50 fps, which represents the highest rate of scientific CMOS cameras. Changing the epoch registration accuracy from a typical 20.0 ms for a mechanical shutter to 0.025 ms, the theoretical value for the electronic shutter of a CMOS camera, improved the orbit accuracy by 4 to 190 %. The ground-based scenario also benefit from the specific CMOS characteristics, but to a lesser extent.

  10. 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


    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...

  11. Orbital pseudotumor (United States)

    ... Goodlick TA, Kay MD, Glaser JS, Tse DT, Chang WJ. Orbital disease and neuro-ophthalmology. In: Tasman ... 423. Review Date 8/20/2016 Updated by: Franklin W. Lusby, MD, ophthalmologist, Lusby Vision Institute, La ...

  12. Foreign body orbital cyst

    DEFF Research Database (Denmark)

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


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

  13. Linear Magnetoelectric Effect by Orbital Magnetism

    NARCIS (Netherlands)

    Scaramucci, A.; Bousquet, E.; Fechner, M.; Mostovoy, M.; Spaldin, N. A.


    We use symmetry analysis and first-principles calculations to show that the linear magnetoelectric effect can originate from the response of orbital magnetic moments to the polar distortions induced by an applied electric field. Using LiFePO4 as a model compound we show that spin-orbit coupling part


    Energy Technology Data Exchange (ETDEWEB)



    There does not appear to be any obvious way to accelerate neutrons, polarized or otherwise, to high energies by themselves. To investigate the behavior of polarized neutrons the authors therefore have to obtain them by accelerating them as components of heavier nuclei, and then sorting out the contribution of the neutrons in the analysis of the reactions produced by the heavy ion beams. The best neutron carriers for this purpose are probably {sup 3}He nuclei and deuterons. A polarized deuteron is primarily a combination of a proton and a neutron with their spins pointing in the same direction; in the {sup 3}He nucleus the spins of the two protons are opposite and the net spin (and magnetic moment) is almost the same as that of a free neutron. Polarized ions other than protons may be accelerated, stored and collided in a ring such as RHIC provided the techniques proposed for polarized proton operation can be adapted (or replaced by other strategies) for these ions. To accelerate polarized particles in a ring, one must make provisions for overcoming the depolarizing resonances that occur at certain energies. These resonances arise when the spin tune (ratio of spin precession frequency to orbit frequency) resonates with a component present in the horizontal field. The horizontal field oscillates with the vertical motion of the particles (due to vertical focusing); its frequency spectrum is dominated by the vertical oscillation frequency and its modulation by the periodic structure of the accelerator ring. In addition, the magnet imperfections that distort the closed orbit vertically contain all integral Fourier harmonics of the orbit frequency.

  15. Orbital angular momentum microlaser (United States)

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


    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.

  16. LEO卫星星下点轨迹保持策略优化研究%Optimal research on satellite track keeping strategy for low earth orbit satellite

    Institute of Scientific and Technical Information of China (English)

    崔鹏; 傅忠谦


    The most LEO(low earth orbit) satellites run in the sun-synchronous orbit.In order to keep their orbit character and achieve the work condition of satellite equipment,satellite track must be kept by orbit control.This paper analyses the local time of descending node is kept by inclination biased and effect for satellite track of inclination biased and decrease of major semi-axis and chronic change of inclination.It gives the keeping method and compute model of adding major semi-axis biased.The simulation results show that the method achieves the demand of track keeping,and the frequency of orbit control is decreased.There is important meaning in practice application.%在轨运行的LEO(low earth orbit)卫星绝大多数是太阳同步回归轨道,为了保持其轨道特性并满足星上载荷工作条件,必须进行星下点轨迹保持.分析了倾角偏置实现降交点地方时保持的同时对星下点轨迹漂移的影响,以及半长轴衰减和倾角长期变化引起的星下点轨迹漂移,给出了增大半长轴偏置量的星下点轨迹保持方法和计算模型.仿真结果显示,此方法不但满足轨迹保持要求,而且减小了轨道维持频度,在工程应用中有重要的意义.

  17. Geometric orbit datum and orbit covers

    Institute of Scientific and Technical Information of China (English)

    梁科; 侯自新


    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.

  18. Characterization of the Uncertainties of CO2 retrievals from OCO (Orbiting Carbon Observatory) Observations (United States)

    Boesch, Hartmut; Crisp, David; Connor, Brian; Obrien, Denis; Baker, David; Miller, Charles

    The Orbiting Carbon Observatory (OCO) mission will make global, space-based measurements of atmospheric carbon dioxide (CO2) with the precision, resolution, and coverage needed to characterize CO2 sources and sinks on regional scales. During its 2-year mission, OCO will fly in a 1:26 PM sun-synchronous orbit with a 16-day ground-track repeat time, just ahead of the EOS Aqua platform. It will carry a single instrument that incorporates three boresighted high-resolution spectrometers designed to measure reflected sunlight in the 0.76-micron O2 A-band and in the CO2 bands at 1.61 and 2.06 microns. OCO is specially designed to be sensitive to near-surface CO2 concentrations and, due to its nadir and sunglint modes, will provide soundings over land and ocean. Here we will discuss the characteristics of OCO soundings and their measurement uncertainties, given by an analysis of the OCO forward model for different surface types, aerosol loadings, and solar zenith angle and we will assess merits of OCO's nadirand glint-viewing modes. We will examine aerosol and cloud statistics derived from MODIS and other satellites to determine the spatio-temporal distribution of the OCO measurement errors and to obtained the expected number of cloud-free OCO soundings from which multi-shot measurement errors are calculated. Finally, we will discuss how well we expect OCO's column-CO2 measurements can constrain the surface sources and sinks. These investigations will provide important feedback to help isolate areas where the retrieval must be improved and give guidance on the optimal observation and sounding selection strategy for OCO.

  19. Lunar Reconnaissance Orbiter (United States)

    Morgan, T.; Chin, G.


    NASA's Lunar Reconnaissance Orbiter (LRO) plans to launch in October 2008 with a companion secondary impactor mission, LCROSS, as the inaugural missions for the Exploration System Mission Directorate. LRO is a pathfinder whose objective is to obtain the needed information to prepare for eventual human return to the Moon. LRO will undertake at least one baseline year of operation with additional extended mission phase sponsored by NASA's Science Mission Directorate. LRO will employ six individual instruments to produce accurate maps and high-resolution images of future landing sites, to assess potential lunar resources, and to characterize the radiation environment. LRO will also test the feasibility of one advanced technology demonstration package. The LRO payload includes: Lunar Orbiter Laser Altimeter (LOLA) which will determine the global topography of the lunar surface at high resolution, measure landing site slopes, surface roughness, and search for possible polar surface ice in shadowed regions; Lunar Reconnaissance Orbiter Camera (LROC) which will acquire targeted narrow angle images of the lunar surface capable of resolving meter-scale features to support landing site selection, as well as wide-angle images to characterize polar illumination conditions and to identify potential resources; Lunar Exploration Neutron Detector (LEND) which will map the flux of neutrons from the lunar surface to search for evidence of water ice, and will provide space radiation environment measurements that may be useful for future human exploration; Diviner Lunar Radiometer Experiment (DLRE) which will chart the temperature of the entire lunar surface at approximately 300 meter horizontal resolution to identify cold-traps and potential ice deposits; Lyman-Alpha Mapping Project (LAMP) which will map the entire lunar surface in the far ultraviolet. LAMP will search for surface ice and frost in the polar regions and provide images of permanently shadowed regions illuminated only

  20. Orbit analysis

    Energy Technology Data Exchange (ETDEWEB)

    Michelotti, L.


    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.

  1. Ion Polarization Scheme for MEIC

    CERN Document Server

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


    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...

  2. Inflammation of the Orbit (United States)

    ... Eye Exams, Study Finds 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 ...

  3. Polar Views of Planet Earth. (United States)

    Brochu, Michel


    In August, 1981, National Aeronautics and Space Administration launched Dynamics Explorer 1 into polar orbit equipped with three cameras built to view the Northern Lights. The cameras can photograph aurora borealis' faint light without being blinded by the earth's bright dayside. Photographs taken by the satellite are provided. (JN)

  4. Ellipsometry with an undetermined polarization state

    NARCIS (Netherlands)

    Lui, F.; Lee, Christopher James; Chen, J.; Chen, Juequan; Louis, Eric; van der Slot, Petrus J.M.; Boller, Klaus J.; Bijkerk, Frederik


    We show that, under the right conditions, one can make highly accurate polarization-based measurements without knowing the absolute polarization state of the probing light field. It is shown that light, passed through a randomly varying birefringent material has a well-defined orbit on the Poincare

  5. Ellipsometry with randomly varying polarization states

    NARCIS (Netherlands)

    Liu, F.; Lee, C. J.; Chen, J. Q.; E. Louis,; van der Slot, P. J. M.; Boller, K. J.; F. Bijkerk,


    We show that, under the right conditions, one can make highly accurate polarization-based measurements without knowing the absolute polarization state of the probing light field. It is shown that light, passed through a randomly varying birefringent material has a well-defined orbit on the Poincar s

  6. Imaging of Orbital Infections


    Seyed Hassan Mostafavi


    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...

  7. Polarization developments

    Energy Technology Data Exchange (ETDEWEB)

    Prescott, C.Y.


    Recent developments in laser-driven photoemission sources of polarized electrons have made prospects for highly polarized electron beams in a future linear collider very promising. This talk discusses the experiences with the SLC polarized electron source, the recent progress with research into gallium arsenide and strained gallium arsenide as a photocathode material, and the suitability of these cathode materials for a future linear collider based on the parameters of the several linear collider designs that exist.

  8. Orbital liposarcoma. (United States)

    Borbolla-Pertierra, A M; Morales-Baños, D R; Martínez-Nava, L R; Garrido-Sánchez, G A; López-Hernández, C M; Velasco-Ramos, P


    The case is presented of a 46-year-old male with right eye proptosis and conjunctival hyperaemia, of 18 months onset. A well-defined intraconal mass was found in the computed tomography. In magnetic resonance this was hypo-intense on T1, enhanced with gadolinium and hyperintense on T2. Excisional biopsy was performed, which was reported as a well-differentiated liposarcoma in the histopathology study. Liposarcoma is a malignant adipose tissue tumour. It is very rare in the orbit, with 5 histological types, the most common being myxoid. The treatment of choice is wide surgical excision and may be accompanied with radiotherapy. As it is an infiltrative tumour, It has a high rate of recurrence. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

  9. Polarization, political

    NARCIS (Netherlands)

    M. Wojcieszak


    Polarization has been studied in three different forms: on a social, group, and individual level. This entry first focuses on the undisputed phenomenon of elite polarization (i.e., increasing adherence of policy positions among the elites) and also outlines different approaches to assessing mass pol

  10. Polar Codes (United States)


    QPSK Gaussian channels . .......................................................................... 39 vi 1. INTRODUCTION Forward error correction (FEC...Capacity of BSC. 7 Figure 5. Capacity of AWGN channel . 8 4. INTRODUCTION TO POLAR CODES Polar codes were introduced by E. Arikan in [1]. This paper...Under authority of C. A. Wilgenbusch, Head ISR Division EXECUTIVE SUMMARY This report describes the results of the project “More reliable wireless

  11. 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...

  12. Polarization holography

    DEFF Research Database (Denmark)

    Nikolova, L.; Ramanujam, P.S.

    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......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...... 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...

  13. Polar Cap Retreat (United States)


    13 August 2004 This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a view of the retreating seasonal south polar cap in the most recent spring in late 2003. Bright areas are covered with frost, dark areas are those from which the solid carbon dioxide has sublimed away. The center of this image is located near 76.5oS, 28.2oW. The scene is large; it covers an area about 250 km (155 mi) across. The scene is illuminated by sunlight from the upper left.

  14. Saturn's Polar Atmosphere

    CERN Document Server

    Sayanagi, Kunio M; Dyudina, Ulyana A; Fletcher, Leigh N; Sánchez-Lavega, Agustin; West, Robert A


    This book chapter, Saturn's Polar Atmosphere, is to be published by Cambridge University Press as part of a multi-volume work edited by Kevin Baines, Michael Flasar, Norbert Krupp, and Thomas Stallard, entitled "Saturn in the 21st Century." This chapter reviews the state of our knowledge about Saturn's polar atmosphere that has been revealed through Earth- and space-based observation as well as theoretical and numerical modeling. In particular, the Cassini mission to Saturn, which has been in orbit around the ringed planet since 2004, has revolutionized our understanding of the planet. The current review updates a previous review by Del Genio et al (2009; Saturn Atmospheric Structure and Dynamics, Chapter 7 of "Saturn from Cassini-Huygens"), written after Cassini's primary mission phase that ended in 2008, by focusing on the north polar region of Saturn and comparing it to the southern high latitudes. Two prominent features in the northern high latitudes are the northern hexagon and the north polar vortex; we...

  15. Small Orbits

    CERN Document Server

    Borsten, L; Ferrara, S; Marrani, A; Rubens, W


    We study both the "large" and "small" U-duality charge orbits of extremal black holes appearing in D = 5 and D = 4 Maxwell-Einstein supergravity theories with symmetric scalar manifolds. We exploit a formalism based on cubic Jordan algebras and their associated Freudenthal triple systems, in order to derive the minimal charge representatives, their stabilizers and the associated "moduli spaces". After recalling N = 8 maximal supergravity, we consider N = 2 and N = 4 theories coupled to an arbitrary number of vector multiplets, as well as N = 2 magic, STU, ST^2 and T^3 models. While the STU model may be considered as part of the general N = 2 sequence, albeit with an additional triality symmetry, the ST^2 and T^3 models demand a separate treatment, since their representative Jordan algebras are Euclidean or only admit non-zero elements of rank 3, respectively. Finally, we also consider minimally coupled N = 2, matter coupled N = 3, and "pure" N = 5 theories.

  16. Recolliding orbits in an intense laser field

    CERN Document Server

    Kamor, Adam; Chandre, Cristel; UZer, Turgay


    We show that a family of key periodic orbits drive the recollision process in a strong circulary polarized laser field. These orbits, coined recolliding periodic orbits, exist for a wide range of parameters and their relative influence changes as the laser and atomic parameters are varied. We find the necessary conditions for recollision-driven nonsequential double ionization to occur. The outlined mechanism is universal in that it applies equally well beyond atoms: The internal structure of the target species plays a minor role in the recollision process.

  17. Updates in Orbital Tumors

    Institute of Scientific and Technical Information of China (English)

    Nila; F.Moeloek


    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.

  18. Polarizing cues. (United States)

    Nicholson, Stephen P


    People categorize themselves and others, creating ingroup and outgroup distinctions. In American politics, parties constitute the in- and outgroups, and party leaders hold sway in articulating party positions. A party leader's endorsement of a policy can be persuasive, inducing co-partisans to take the same position. In contrast, a party leader's endorsement may polarize opinion, inducing out-party identifiers to take a contrary position. Using survey experiments from the 2008 presidential election, I examine whether in- and out-party candidate cues—John McCain and Barack Obama—affected partisan opinion. The results indicate that in-party leader cues do not persuade but that out-party leader cues polarize. This finding holds in an experiment featuring President Bush in which his endorsement did not persuade Republicans but it polarized Democrats. Lastly, I compare the effect of party leader cues to party label cues. The results suggest that politicians, not parties, function as polarizing cues.

  19. Imaging of Orbital Infections

    Directory of Open Access Journals (Sweden)

    Seyed Hassan Mostafavi


    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.

  20. Preseptal Cellulitis, Orbital Cellulitis, Orbital Abscess


    Rana Altan Yaycıoğlu


    Patients with orbital infections present to our clinic usually with unilateral pain, hyperemia, and edema of the eyelids. The differentiation between preseptal and orbital cellulitis is utmost important in that the second requires hospitalization. Since in orbital cellulitis, the tissues posterior to the orbital septum are involved, signs such as conjunctival chemosis, limited eye movement, decreased vision, as well as afferent pupil defect secondary to optic nerve involvement may al...

  1. Bilateral orbital cavernous haemangiomas.


    Fries, P D; Char, D. H.


    Simultaneous bilateral orbital lesions are rare. The differential diagnosis includes orbital pseudotumour, metastasis, leukaemia, lymphoma, Wegener's granulomatosis, and neurofibromatosis. We report what we believe to be the first case of bilateral orbital cavernous haemangiomas.

  2. Mesoscopic Rings with Spin-Orbit Interactions (United States)

    Berche, Bertrand; Chatelain, Christophe; Medina, Ernesto


    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…

  3. Mars orbiter redirected in bid to find Beagle

    CERN Multimedia


    "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).

  4. Orbit Determination Toolbox (United States)

    Carpenter, James R.; Berry, Kevin; Gregpru. Late; Speckman, Keith; Hur-Diaz, Sun; Surka, Derek; Gaylor, Dave


    The Orbit Determination Toolbox is an orbit determination (OD) analysis tool based on MATLAB and Java that provides a flexible way to do early mission analysis. The toolbox is primarily intended for advanced mission analysis such as might be performed in concept exploration, proposal, early design phase, or rapid design center environments. The emphasis is on flexibility, but it has enough fidelity to produce credible results. Insight into all flight dynamics source code is provided. MATLAB is the primary user interface and is used for piecing together measurement and dynamic models. The Java Astrodynamics Toolbox is used as an engine for things that might be slow or inefficient in MATLAB, such as high-fidelity trajectory propagation, lunar and planetary ephemeris look-ups, precession, nutation, polar motion calculations, ephemeris file parsing, and the like. The primary analysis functions are sequential filter/smoother and batch least-squares commands that incorporate Monte-Carlo data simulation, linear covariance analysis, measurement processing, and plotting capabilities at the generic level. These functions have a user interface that is based on that of the MATLAB ODE suite. To perform a specific analysis, users write MATLAB functions that implement truth and design system models. The user provides his or her models as inputs to the filter commands. The software provides a capability to publish and subscribe to a software bus that is compliant with the NASA Goddard Mission Services Evolution Center (GMSEC) standards, to exchange data with other flight dynamics tools to simplify the flight dynamics design cycle. Using the publish and subscribe approach allows for analysts in a rapid design center environment to seamlessly incorporate changes in spacecraft and mission design into navigation analysis and vice versa.

  5. Direct mapping of spin and orbital entangled wave functions under interband spin-orbit coupling of giant Rashba spin-split surface states (United States)

    Noguchi, Ryo; Kuroda, Kenta; Yaji, K.; Kobayashi, K.; Sakano, M.; Harasawa, A.; Kondo, Takeshi; Komori, F.; Shin, S.


    We use spin- and angle-resolved photoemission spectroscopy (SARPES) combined with a polarization-variable laser and investigate the spin-orbit coupling effect under interband hybridization of Rashba spin-split states for the surface alloys Bi/Ag(111) and Bi/Cu(111). In addition to the conventional band mapping of photoemission for Rashba spin splitting, the different orbital and spin parts of the surface wave function are directly imaged into energy-momentum space. It is unambiguously revealed that the interband spin-orbit coupling modifies the spin and orbital character of the Rashba surface states leading to the enriched spin-orbital entanglement and the pronounced momentum dependence of the spin polarization. The hybridization thus strongly deviates the spin and orbital characters from the standard Rashba model. The complex spin texture under interband spin-orbit hybridization proposed by first-principles calculation is experimentally unraveled by SARPES with a combination of p - and s -polarized light.

  6. Study of the transfer between libration point orbits and lunar orbits in Earth-Moon system (United States)

    Cheng, Yu; Gómez, Gerard; Masdemont, Josep J.; Yuan, Jianping


    This paper is devoted to the study of the transfer problem from a libration point orbit of the Earth-Moon system to an orbit around the Moon. The transfer procedure analysed has two legs: the first one is an orbit of the unstable manifold of the libration orbit and the second one is a transfer orbit between a certain point on the manifold and the final lunar orbit. There are only two manoeuvres involved in the method and they are applied at the beginning and at the end of the second leg. Although the numerical results given in this paper correspond to transfers between halo orbits around the L_1 point (of several amplitudes) and lunar polar orbits with altitudes varying between 100 and 500 km, the procedure we develop can be applied to any kind of lunar orbits, libration orbits around the L_1 or L_2 points of the Earth-Moon system, or to other similar cases with different values of the mass ratio.

  7. Lunar true polar wander inferred from polar hydrogen. (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


    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

  8. Orbital dystopia due to orbital roof defect. (United States)

    Rha, Eun Young; Joo, Hong Sil; Byeon, Jun Hee


    We performed a retrospective review of patients who presented with delayed dystopia as a consequence of an orbital roof defect due to fractures and nontraumatic causes to search for a correlation between orbital roof defect size and surgical indications for the treatment thereof. Retrospective analyses were performed in 7 patients, all of whom presented with delayed dystopia due to orbital roof defects, between January 2001 and June 2011. The causes of orbital roof defects were displaced orbital roof fractures (5 cases), tumor (1 case), and congenital sphenoid dysplasia (1 case). All 7 patients had initially been treated conservatively and later presented with significant dystopia. The sizes of the defects were calculated on computed tomographic scans. Among the 7 patients, aspiration of cerebrospinal fluid, which caused ocular symptoms, in 1 patient with minimal displaced orbital roof and reconstruction with calvarial bone, titanium micromesh, or Medpor in 6 other patients were performed. The minimal size of the orbital roof in patients who underwent orbital roof reconstruction was 1.2 cm (defect height) x 1.0 cm (defect length), 0.94 cm(2). For all patients with orbital dystopia, displacement of the globe was corrected without any complications, regardless of whether the patient was evaluated grossly or by radiology. In this retrospective study, continuous monitoring of clinical signs and active surgical management should be considered for cases in which an orbital roof defect is detected, even if no definite symptoms are noted, to prevent delayed sequelae.

  9. 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


    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...

  10. Polarized Campuses. (United States)

    Parr, Susan Resneck


    On college campuses, the climate is polarized because of intolerance and discrimination, censorship, factionalism, and anger among students and faculty. As a result, the campus is in danger of becoming dominated by political issues and discouraging the exchange of ideas characteristic of a true liberal arts education. (MSE)

  11. Generation and detection of orbital angular momentum via metasurface. (United States)

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


    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


    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. Inclusive quasielastic scattering of polarized electrons from polarized nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Amaro, J.E. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Center for Theoretical Physics]|[Universidad de Granada (Spain). Dept. de Fisica Moderna]|[Massachusetts Inst. of Tech., Cambridge, MA (United States). Lab. for Nuclear Science]|[Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics; Caballero, J.A. [Consejo Superior de Investigaciones Cientificas (CSIC), Madrid (Spain). Inst. de Estructura de la Materia]|[Sevilla Univ. (Spain). Dept. de Fisica Atomica, Molecular y Nuclear; Donnelly, T.W. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Center for Theoretical Physics]|[Massachusetts Inst. of Tech., Cambridge, MA (United States). Lab. for Nuclear Science]|[Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Physics; Moya de Guerra, E. [Consejo Superior de Investigaciones Cientificas (CSIC), Madrid (Spain). Inst. de Estructura de la Materia


    The inclusive quasielastic response functions that appear in the scattering of polarized electrons from polarized nuclei are computed and analyzed for several closed-shell-minus-one nuclei with special attention paid to {sup 39}K. Results are presented using two models for the ejected nucleon - when described by a distorted wave in the continuum shell model or by a plane wave in PWIA with on- and off-shell nucleons. Relativistic effects in kinematics and in the electromagnetic current have been incorporated throughout. Specifically, the recently obtained expansion of the electromagnetic current in powers only of the struck nucleon`s momentum is employed for the on-shell current and the effects of the first-order terms (spin-orbit and convection) are compared with the zeroth-order (charge and magnetization) contributions. The use of polarized inclusive quasielastic electron scattering as a tool for determining near-valence nucleon momentum distributions is discussed. (orig.).

  14. Polarization in free electron lasers

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  15. Spin-orbit interactions of light

    CERN Document Server

    Bliokh, K Y; Nori, F; Zayats, A V


    Light carries spin and orbital angular momentum. These dynamical properties are determined by the polarization and spatial degrees of freedom of light. Modern nano-optics, photonics, and plasmonics, tend to explore subwavelength scales and additional degrees of freedom of structured, i.e., spatially-inhomogeneous, optical fields. In such fields, spin and orbital properties become strongly coupled with each other. We overview the fundamental origins and important applications of the main spin-orbit interaction phenomena in optics. These include: spin-Hall effects in inhomogeneous media and at optical interfaces, spin-dependent effects in nonparaxial (focused or scattered) fields, spin-controlled shaping of light using anisotropic structured interfaces (metasurfaces), as well as robust spin-directional coupling via evanescent near fields. We show that spin-orbit interactions are inherent in all basic optical processes, and they play a crucial role at subwavelength scales and structures in modern optics.

  16. Polarized Spinoptics and Symplectic Physics

    CERN Document Server

    Duval, Christian


    We recall the groundwork of spinoptics based on the coadjoint orbits, of given color and spin, of the group of isometries of Euclidean three-space; this model has originally been put forward by Souriau in his treatise "Structure des Syst\\'emes Dynamiques", whose manuscript was initially entitled "Physique symplectique". We then set up a model of polarized spinoptics, namely an extension of geometrical optics accounting for elliptically polarized light rays in terms of a certain fibre bundle associated with the bundle of Euclidean frames of a given Riemannian three-manifold. The characteristic foliation of a natural presymplectic two-form introduced on this bundle via the Ansatz of minimal coupling is determined, yielding a set of differential equations governing the trajectory of light, as well as the evolution of polarization in this Riemannian manifold. Those equations, when specialized to the Fermat metric (for a slowly varying refractive index), enable us to recover, and justify, a set of differential equ...

  17. North Polar Cap (United States)


    [figure removed for brevity, see original site] This week we will be looking at five examples of laminar wind flow on the north polar cap. On Earth, gravity-driven south polar cap winds are termed 'catabatic' winds. Catabatic winds begin over the smooth expanse of the cap interior due to temperature differences between the atmosphere and the surface. Once begun, the winds sweep outward along the surface of the polar cap toward the sea. As the polar surface slopes down toward sealevel, the wind speeds increase. Catabatic wind speeds in the Antartic can reach several hundreds of miles per hour. In the images of the Martian north polar cap we can see these same type of winds. Notice the streamers of dust moving downslope over the darker trough sides, these streamers show the laminar flow regime coming off the cap. Within the trough we see turbulent clouds of dust, kicked up at the trough base as the winds slow down and enter a chaotic flow regime. The horizontal lines in these images are due to framelet overlap and lighting conditions over the bright polar cap. Image information: VIS instrument. Latitude 86.5, Longitude 64.5 East (295.5 West). 40 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen

  18. 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


    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...

  19. Preseptal Cellulitis, Orbital Cellulitis, Orbital Abscess

    Directory of Open Access Journals (Sweden)

    Rana Altan Yaycıoğlu


    Full Text Available Patients with orbital infections present to our clinic usually with unilateral pain, hyperemia, and edema of the eyelids. The differentiation between preseptal and orbital cellulitis is utmost important in that the second requires hospitalization. Since in orbital cellulitis, the tissues posterior to the orbital septum are involved, signs such as conjunctival chemosis, limited eye movement, decreased vision, as well as afferent pupil defect secondary to optic nerve involvement may also be observed. Prompt intravenous antibiotic treatment should be started, and surgical drainage may be performed if patient shows failure to improve in 48 hours despite optimal management. Without treatment, the clinical course may progress to subperiosteal or orbital abscess, and even to cavernous sinus thrombosis. (Turk J Ophthalmol 2012; 42: Supplement 52-6

  20. Local orbitals in electron scattering calculations* (United States)

    Winstead, Carl L.; McKoy, Vincent


    We examine the use of local orbitals to improve the scaling of calculations that incorporate target polarization in a description of low-energy electron-molecule scattering. After discussing the improved scaling that results, we consider the results of a test calculation that treats scattering from a two-molecule system using both local and delocalized orbitals. Initial results are promising. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  1. Impact on Spin Tune From Horizontal Orbital Angle Between Snakes and Orbital Angle Between Spin Rotators

    Energy Technology Data Exchange (ETDEWEB)

    Bai,M.; Ptitsyn, V.; Roser, T.


    To keep the spin tune in the spin depolarizing resonance free region is required for accelerating polarized protons to high energy. In RHIC, two snakes are located at the opposite side of each accelerator. They are configured to yield a spin tune of 1/2. Two pairs of spin rotators are located at either side of two detectors in each ring in RHIC to provide longitudinal polarization for the experiments. Since the spin rotation from vertical to longitudinal is localized between the two rotators, the spin rotators do not change the spin tune. However, due to the imperfection of the orbits around the snakes and rotators, the spin tune can be shifted. This note presents the impact of the horizontal orbital angle between the two snakes on the spin tune, as well as the effect of the vertical orbital angle between two rotators at either side of the collision point on the spin tune.

  2. Lunar Orbiter Photo Gallery (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...

  3. ASC Champ Orbit Model

    DEFF Research Database (Denmark)

    Riis, Troels; Jørgensen, John Leif


    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....

  4. Polygons in billiard orbits

    CERN Document Server

    Don, Henk


    We study the geometry of billiard orbits on rectangular billiards. A truncated billiard orbit induces a partition of the rectangle into polygons. We prove that thirteen is a sharp upper bound for the number of different areas of these polygons.

  5. The ESA earth observation polar platform programme (United States)

    Rast, M.; Readings, C. J.


    The overall scenario of ESA earth observation polar platform program is reviewed with particular attention given to instruments currently being considered for flight on the first European polar platforms. The major objectives of the mission include monitoring the earth's environment on various scales; management and monitoring of the earth's resources; improvement of the service provided to the worldwide operational meteorological community, investigation of the structure and dynamics of the earth's crust and interior. The program encompasses four main elements: an ERS-1 follow-on mission (ERS-2), a solid earth gravity mission (Aristoteles), a Meteosat Second Generation, and a series of polar orbit earth observation missions.

  6. Traumatic transconjunctival orbital emphysema.


    Stroh, E M; Finger, P T


    Orbital emphysema can be produced by trans-conjunctival migration of air from a high pressure airgun. In an industrial accident an 8 mm conjunctival laceration was produced in the superior fornix which acted as a portal of entry for air into the subconjunctival, subcutaneous, and retrobulbar spaces. Computed tomography revealed no evidence of orbital fracture and showed that traumatic orbital emphysema occurred without a broken orbital bone.

  7. Introducing Earth's Orbital Eccentricity (United States)

    Oostra, Benjamin


    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  8. PALOMA: A Magnetic CV between Polars and Intermediate Polars (United States)

    Joshi, Arti; Pandey, J. C.; Singh, K. P.; Agrawal, P. C.


    We present analyses of archival X-ray data obtained from the XMM-Newton satellite and optical photometric data obtained from 1 m class telescopes of ARIES, Nainital of a magnetic cataclysmic variable (MCV) Paloma. Two persistent periods at 156 ± 1 minutes and 130 ± 1 minutes are present in the X-ray data, which we interpret as the orbital and spin periods, respectively. These periods are similar to those obtained from the previous as well as new optical photometric observations. The soft-X-ray excess seen in the X-ray spectrum of Paloma and the averaged X-ray spectra are well fitted by two-temperature plasma models with temperatures of {0.10}-0.01+0.02 and {13.0}-0.5+0.5 keV with an Fe Kα line and an absorbing column density of 4.6 × 1022 cm‑2. This material partially covers 60 ± 2% of the X-ray source. We also present the orbital and spin-phase-resolved spectroscopy of Paloma in the 0.3{--}10.0 {keV} energy band and find that the X-ray spectral parameters show orbital and spin-phase dependencies. New results obtained from optical and X-ray studies of Paloma indicate that it belongs to a class of a few magnetic CVs that seem to have the characteristics of both the polars and the intermediate polars.

  9. Polar Ring Galaxies and Warps (United States)

    Combes, F.

    Polar ring galaxies, where matter is in equilibrium in perpendicular orbits around spiral galaxies, are ideal objects to probe the 3D shapes of dark matter halos. The conditions to constrain the halos are that the perpendicular system does not strongly perturb the host galaxy, or that it is possible to derive back its initial shape, knowing the formation scenario of the polar ring. The formation mechanisms are reviewed: mergers, tidal accretion, or gas accretion from cosmic filaments. The Tully-Fisher diagram for polar rings reveals that the velocity in the polar plane is higher than in the host plane, which can only be explained if the dark matter is oblate and flattened along the polar plane. Only a few individual systems have been studied in details, and 3D shapes of their haloes determined by several methods. The high frequency of warps could be explained by spontaneous bending instability, if the disks are sufficiently self-gravitating, which can put constraints on the dark matter flattening.

  10. Polar ring galaxies and warps

    CERN Document Server

    Combes, F


    Polar ring galaxies, where matter is in equilibrium in perpendicular orbits around spiral galaxies, are ideal objects to probe the 3D shapes of dark matter halos. The conditions to constrain the halos are that the perpendicular system does not strongly perturb the host galaxy, or that it is possible to derive back its initial shape, knowing the formation scenario of the polar ring. The formation mechanisms are reviewed: mergers, tidal accretion, or gas accretion from cosmic filaments. The Tully-Fisher diagram for polar rings reveals that the velocity in the polar plane is higher than in the host plane, which can only be explained if the dark matter is oblate and flattened along the polar plane. Only a few individual systems have been studied in details, and 3D shapes of their haloes determined by several methods. The high frequency of warps could be explained by spontaneous bending instability, if the disks are sufficiently self-gravitating, which can put constraints on the dark matter flattening.

  11. International Solar Terrestrial Physics (ISTP) program polar mission (United States)

    Sanford, R.; Sizemore, K. O.


    The polar spacecraft will be launched from Western Test Ranges (WTR) into a 2 earth radii by 9 earth radii polar orbit, with apogee near the North Pole. Information is presented on the following topics: Deep Space Network support, frequency assignments, telemetry, command, and ranging.

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

    Institute of Scientific and Technical Information of China (English)

    HU Xiao-Ying; ZHOU Ya-Jun


    @@ 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.

  13. Polarized Proton Collisions at 205GeV at RHIC (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.


    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.

  14. Painless orbital myositis

    Directory of Open Access Journals (Sweden)

    Rahul T Chakor


    Full Text Available Idiopathic orbital inflammation is the third most common orbital disease, following Graves orbitopathy and lymphoproliferative diseases. We present a 11 year old girl with 15 days history of painless diplopia. There was no history of fluctuation of symptoms, drooping of eye lids or diminished vision. She had near total restricted extra-ocular movements and mild proptosis of the right eye. There was no conjunctival injection, chemosis, or bulb pain. There was no eyelid retraction or lid lag. Rest of the neurological examination was unremarkable.Erythrocyte sedimentation rate was raised with eosinophilia. Antinuclear antibodies were positive. Liver, renal and thyroid functions were normal. Antithyroid, double stranded deoxyribonucleic acid and acetylcholine receptor antibodies were negative. Repetitive nerve stimulation was negative. Magnetic resonance imaging (MRI of the orbit was typical of orbital myositis. The patient responded to oral steroids. Orbital myositis can present as painless diplopia. MRI of orbit is diagnostic in orbital myositis.

  15. Orbital fractures: a review

    Directory of Open Access Journals (Sweden)

    Jeffrey M Joseph


    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 

  16. Exomars orbiter science and data-relay mission / looking for trace gases on Mars (United States)

    Fratacci, Olivier

    spectrometers, mapper and imagers will be embarked, providing an enhanced science return compared to already flying instruments on previous Mars missions like MGS, MEX and MRO. In particular trace gases detection by sun occultation is promoted as first priority followed by quasi continuous limb to limb atmosphere scan and strategic surface high resolution imaging. The multiple instrument pointing requirements combined with a non-Sun-synchronous orbit, led to selection of a "Sun-nadir yaw steering" pointing strategy. A designated axis is pointed to nadir, while the yaw orientation about nadir is controlled to keep the long axis of the solar arrays normal to the Sun vector. This pointing strategy keeps a spacecraft face always pointed away from both the Sun and Mars allowing implementation of the radiators of cryogenic instruments. After the 2 years science phase the OM will also provide a data-relay function with a UHF proximity link for about four years to all future Mars surface assets including the Exomars Rover planned for launch in 2018. Thales Alenia Space will build the CRSM on the basis of the existing Spacebus telecommunication platform to reduce costs and meet the Exomars challenging performance and schedule. The OHB company in Bremen will procure and assemble the Mechanical, Thermal and Propulsion subsystems. The system PDR is planned end of 2010 and the announcement of opportunities for science payloads was issued in January 2010.

  17. Valley precession and valley polarization in graphene with inter-valley coupling (United States)

    Wu, Qing-Ping; Liu, Zheng-Fang; Chen, Ai-Xi; Xiao, Xian-Bo; Zhang, Heng; Miao, Guo-Xing


    We theoretically investigate the valley precession and valley polarization in graphene under inter-valley coupling. Our results show that the inter-valley coupling can induce valley polarization in graphene and also precess valleys in real space in a manner similar to the Rashba spin-orbit interaction rotating spins. Moreover, using strain modulation, we can achieve high valley polarization with large valley-polarized currents. These findings provide a new way to create and manipulate valley polarization in graphene.

  18. Polar Shapelets

    CERN Document Server

    Massey, R; Massey, Richard; Refregier, Alexandre


    The shapelets method for astronomical image analysis is based around the decomposition of localised objects into a series of orthogonal components with particularly convenient mathematical properties. We extend the "Cartesian shapelet" formalism from earlier work, and construct "polar shapelet" basis functions that separate an image into components with explicit rotational symmetries. This provides a more compact representation of typical galaxy shapes, and its physical interpretation is frequently more intuitive. Linear coordinate transformations can be simply expressed using this basis set, and shape measures (including object photometry, astrometry and galaxy morphology estimators) take a naturally elegant form. Particular attention is paid to the analysis of astronomical survey images, and we test shapelet techniques with real data from the Hubble Space Telescope. We present a practical method to automatically optimise the quality of an arbitrary shapelet decomposition in the presence of noise, pixellisat...

  19. Europa Planetary Protection for Juno Jupiter Orbiter (United States)

    Bernard, Douglas E.; Abelson, Robert D.; Johannesen, Jennie R.; Lam, Try; McAlpine, William J.; Newlin, Laura E.


    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.

  20. The Exoplanet Orbit Database

    CERN Document Server

    Wright, Jason T; Marcy, Geoffrey W; Han, Eunkyu; Feng, Ying; Johnson, John Asher; Howard, Andrew W; Valenti, Jeff A; Anderson, Jay; Piskunov, Nikolai


    We present a database of well determined orbital parameters of exoplanets. This database comprises spectroscopic orbital elements measured for 421 planets orbiting 357 stars from radial velocity and transit measurements as reported in the literature. We have also compiled fundamental transit parameters, stellar parameters, and the method used for the planets discovery. This Exoplanet Orbit Database includes all planets with robust, well measured orbital parameters reported in peer-reviewed articles. The database is available in a searchable, filterable, and sortable form on the Web at through the Exoplanets Data Explorer Table, and the data can be plotted and explored through the Exoplanets Data Explorer Plotter. We use the Data Explorer to generate publication-ready plots giving three examples of the signatures of exoplanet migration and dynamical evolution: We illustrate the character of the apparent correlation between mass and period in exoplanet orbits, the selection different biase...

  1. 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)


    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.

  2. Preseptal and orbital cellulitis


    Emine Akçay; Gamze Dereli Can; Nurullah Çağıl


    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...

  3. Orbital inflammation: Corticosteroids first. (United States)

    Dagi Glass, Lora R; Freitag, Suzanne K


    Orbital inflammation is common, and may affect all ages and both genders. By combining a thorough history and physical examination, targeted ancillary laboratory testing and imaging, a presumptive diagnosis can often be made. Nearly all orbital inflammatory pathology can be empirically treated with corticosteroids, thus obviating the need for histopathologic diagnosis prior to initiation of therapy. In addition, corticosteroids may be effective in treating concurrent systemic disease. Unless orbital inflammation responds atypically or incompletely, patients can be spared biopsy.

  4. Geometric orbit datum and orbit covers

    Institute of Scientific and Technical Information of China (English)

    LIANG; Ke(


    [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.

  5. Globally Polarized Quark-gluon Plasma in Non-central A+ACollisions

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Zuo-tang; Wang, Xin-Nian


    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.

  6. 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


    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.

  7. Spin-orbit scattering visualized in quasiparticle interference (United States)

    Kohsaka, Y.; Machida, T.; Iwaya, K.; Kanou, M.; Hanaguri, T.; Sasagawa, T.


    In the presence of spin-orbit coupling, electron scattering off impurities depends on both spin and orbital angular momentum of electrons—spin-orbit scattering. Although some transport properties are subject to spin-orbit scattering, experimental techniques directly accessible to this effect are limited. Here we show that a signature of spin-orbit scattering manifests itself in quasiparticle interference (QPI) imaged by spectroscopic-imaging scanning tunneling microscopy. The experimental data of a polar semiconductor BiTeI are well reproduced by numerical simulations with the T -matrix formalism that include not only scalar scattering normally adopted but also spin-orbit scattering stronger than scalar scattering. To accelerate the simulations, we extend the standard efficient method of QPI calculation for momentum-independent scattering to be applicable even for spin-orbit scattering. We further identify a selection rule that makes spin-orbit scattering visible in the QPI pattern. These results demonstrate that spin-orbit scattering can exert predominant influence on QPI patterns and thus suggest that QPI measurement is available to detect spin-orbit scattering.

  8. Reconfigurable thz polarizer

    DEFF Research Database (Denmark)


    The present invention provides a polarizer. The polarizer comprises a first membrane having a first polarization region comprising a first plurality of membrane perforations; a second membrane having a second polarization region comprising a second plurality of membrane perforations; and a support...... with one or more membrane perforations in the second plurality of perforations in a direction normal to the first polarization region or normal to the second polarization region, resulting in corresponding one or more openings in said direction....

  9. Congenital orbital encephalocele, orbital dystopia, and exophthalmos. (United States)

    Hwang, Kun; Kim, Han Joon


    We present here an exceedingly rare variant of a nonmidline basal encephalocele of the spheno-orbital type, and this was accompanied with orbital dystopia in a 56-year-old man. On examination, his left eye was located more inferolaterally than his right eye, and the patient said this had been this way since his birth. The protrusion of his left eye was aggravated when he is tired. His naked visual acuity was 0.7/0.3, and the ocular pressure was 14/12 mm Hg. The exophthalmometry was 10/14 to 16 mm. His eyeball motion was not restricted, yet diplopia was present in all directions. The distance from the midline to the medial canthus was 20/15 mm. The distance from the midline to the midpupillary line was 35/22 mm. The vertical dimension of the palpebral fissure was 12/9 mm. The height difference of the upper eyelid margin was 11 mm, and the height difference of the lower eyelid margin was 8 mm. Facial computed tomography and magnetic resonance imaging showed left sphenoid wing hypoplasia and herniation of the left anterior temporal pole and dura mater into the orbit, and this resulted into left exophthalmos and encephalomalacia in the left anterior temporal pole. To the best of our knowledge, our case is the second case of basal encephalocele and orbital dystopia.

  10. Patterns of orbital disorders

    Directory of Open Access Journals (Sweden)

    Balasubramanian Thiagarajan


    Full Text Available This article discusses various patterns of presentations of orbital lesions. Since this article has been authored by an otolaryngologist, the entire concept has been viewed from otolaryngologist's angle. With the advent of nasal endoscope trans nasal access to orbit is becoming the order of the day. Major advantage being that external skin incision is avoided.



    Walid Ali Rahoma


    The present study deal with constructing an analytical model within Hamiltonian formulation to design invariant relative orbits due to the perturbation of J2 and the lunisolar attraction. To fade the secular drift separation over the time between two neighboring orbits, two second order conditions that guarantee that drift are derived and enforced to be equal.

  12. Reticulohistiocytoma of the Orbit (United States)

    Weissman, Heather M.; Hayek, Brent R.; Grossniklaus, Hans E.


    Reticulohistiocytoma is a rare, benign histiocytic proliferation of the skin or soft tissue. While ocular involvement has been documented in the past, there have been no previously reported cases of reticulohistiocytoma of the orbit. In this report, the authors describe a reticulohistiocytoma of the orbit in a middle-aged woman. PMID:24807799

  13. Orbital Plots Using Gnuplot (United States)

    Moore, Brian G.


    The plotting program Gnuplot is freely available, general purpose, easy to use, and available on a variety of platforms. Complex three-dimensional surfaces, including the familiar angular parts of the hydrogen atom orbitals, are easily represented using Gnuplot. Contour plots allow viewing the radial and angular variation of the probability density in an orbital. Examples are given of how Gnuplot is used in an undergraduate physical chemistry class to view familiar atomic orbitals in new ways or to generate views of orbital functions that the student may have not seen before. Gnuplot may also be easily integrated into the environment of a Web page; an example of this is discussed (and is available at The plotting commands are entered with a form and a CGI script is used to run Gnuplot and display the result back to the browser.

  14. Aerosol Scattering Phase Function Retrieval From Polar Orbiting Satellites (United States)


    instrument of the AERONET is the CIMEL Electronique 318A spectral radiometer (Figure 6) is a solar powered weather hardy robotically pointed sun and sky... CIMEL Spectral Radiometer (from Holbren, 2004) 12 1Noldova , N 47 00󈧄", E 28 48,57"% Alt 205 Yn, PI : Brent_Holben. brenttý Level

  15. Plan for Space Station Polar-Orbiting Platform. (United States)


    precipitation , sea surface temperature, sea ice, ocean chlorophyll, surface winds, wave height, ocean circulation, snow cover, land use, vegetation, crops...alng detviercale the hasltspectra Line Array (andva orfh ftreiagn dvies Thhoerfexile tydperfiagin Inhestmen thatin wol eneftrmolih on a polarin... Precipitation estimation y.F o Global radiation balance studies e Ice, snow, and frost mapping * Sea surface temperature and ocean current boundary mapping

  16. Orbital and spin variability of the Intermediate Polar BG CMi

    CERN Document Server

    Kim, Y G; Park, S S; Jeon, Y B


    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...

  17. 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.


    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...... particles within a field where the transverse energy circulation is associated exclusively with the spin flow. This result can be treated as the first demonstration of mechanical action of the spin flow of a light field....

  18. 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)


    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.

  19. Orbit Stabilization of Nanosat

    Energy Technology Data Exchange (ETDEWEB)



    An algorithm is developed to control a pulsed {Delta}V thruster on a small satellite to allow it to fly in formation with a host satellite undergoing time dependent atmospheric drag deceleration. The algorithm uses four short thrusts per orbit to correct for differences in the average radii of the satellites due to differences in drag and one thrust to symmetrize the orbits. The radial difference between the orbits is the only input to the algorithm. The algorithm automatically stabilizes the orbits after ejection and includes provisions to allow azimuthal positional changes by modifying the drag compensation pulses. The algorithm gives radial and azimuthal deadbands of 50 cm and 3 m for a radial measurement accuracy of {+-} 5 cm and {+-} 60% period variation in the drag coefficient of the host. Approaches to further reduce the deadbands are described. The methodology of establishing a stable orbit after ejection is illustrated in an appendix. The results show the optimum ejection angle to minimize stabilization thrust is upward at 86{sup o} from the orbital velocity. At this angle the stabilization velocity that must be supplied by the thruster is half the ejection velocity. An ejection velocity of 0.02 m/sat 86{sup o} gives an azimuthal separation after ejection and orbit stabilization of 187 m. A description of liquid based gas thrusters suitable for the satellite control is included in an appendix.

  20. Spin Orbit Torque in Ferromagnetic Semiconductors

    KAUST Repository

    Li, Hang


    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

  1. Polarized Light in Astronomy. (United States)

    King, D. J.


    The application of very sensitive electronic detecting devices during the last decade has revolutionized and revitalized the study of polarization in celestial objects. The nature of polarization, how polaroids work, interstellar polarization, dichroic filters, polarization by scattering, and modern polarimetry are among the topics discussed. (JN)

  2. Relativistic Static Thin Disks of Polarized Matter (United States)

    Navarro, Anamaria; Lora-Clavijo, F. D.; González, Guillermo A.


    An infinite family of exact solutions of the electrovacuum Einstein-Maxwell equations is presented. The family is static, axially symmetric and describe thin disks composed by electrically polarized material in a conformastatic spacetime. The form of the conformastatic metric allows us to write down the metric functions and the electromagnetic potentials in terms of a solution of the Laplace equation. We find a general expression for the surface energy density of the disk, the pressure, the polarization vector, the electromagnetic fields and the velocity rotation for circular orbits. As an example, we present the first model of the family and show the behavior of the different physical variables.

  3. Classifying spaces of degenerating polarized Hodge structures

    CERN Document Server

    Kato, Kazuya


    In 1970, Phillip Griffiths envisioned that points at infinity could be added to the classifying space D of polarized Hodge structures. In this book, Kazuya Kato and Sampei Usui realize this dream by creating a logarithmic Hodge theory. They use the logarithmic structures begun by Fontaine-Illusie to revive nilpotent orbits as a logarithmic Hodge structure. The book focuses on two principal topics. First, Kato and Usui construct the fine moduli space of polarized logarithmic Hodge structures with additional structures. Even for a Hermitian symmetric domain D, the present theory is a refinem

  4. Quark Orbital Angular Momentum

    Directory of Open Access Journals (Sweden)

    Burkardt Matthias


    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.

  5. Prototyping LHC Orbit Control

    CERN Document Server

    Wijnands, Thijs; Srinivasan, B


    Orbit correction consists in adjusting the strengths of the corrector magnets to make the measured beam position match a predefined reference. In the LHC, this involves around 2000 sensors and more than 1000 actuators that are distributed along both rings. The orbit correction scheme should be able to compensate for very slow orbit drifts in the range of a 10-2 Hz but also for fast motions (vibrations) up to 1 Hz. In this paper we investigate correction schemes that could be used in either case. The choice of design formalisms is based on the experience we gained with the SPS and the LEP.

  6. Bell's measure and implementing quantum Fourier transform with orbital angular momentum of classical light. (United States)

    Song, Xinbing; Sun, Yifan; Li, Pengyun; Qin, Hongwei; Zhang, Xiangdong


    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.

  7. Final-state interaction and recoil polarization in (e,e'p) reactions: comparison with the polarized target case

    Energy Technology Data Exchange (ETDEWEB)

    Amaro, J.E. [Departamento de Fisica Moderna, Universidad de Granada, Granada 18071 (Spain)]. E-mail:; Caballero, J.A. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, Apdo. 1065, Sevilla 41080 (Spain); Donnelly, T.W. [Center for Theoretical Physics, Laboratory for Nuclear Science and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Kazemi Tabatabaei, F. [Departamento de Fisica Moderna, Universidad de Granada, Granada 18071 (Spain)


    A study of the total cross section for polarized proton knockout in (e,e'p->) reactions is carried out for the closed-shell nucleus {sup 40}Ca. The dependence of FSI effects on polarization observables viewed as functions of the nucleon polarization angles is analyzed and interpreted within the basis of a semi-classical model for the orbit of the struck nucleon and trajectory of the ejected nucleon. A comparison with the case of a {sup 39}K polarized target and unpolarized protons is performed.

  8. Suppression of spin-orbit effects in 1D system


    Entin, M. V.; Magarill, L. I.


    We report the absence of spin effects such as spin-galvanic effect, spin polarization and spin current under static electric field and inter-spin-subband absorption in 1D system with spin-orbit interaction of arbitrary form. It was also shown that the accounting for the direct interaction of electron spin with magnetic field violates this statement.

  9. Mapping enzymatic catalysis using the effective fragment molecular orbital method

    DEFF Research Database (Denmark)

    Svendsen, Casper Steinmann; Fedorov, Dmitri G.; Jensen, Jan Halborg


    We extend the Effective Fragment Molecular Orbital (EFMO) method to the frozen domain approach where only the geometry of an active part is optimized, while the many-body polarization effects are considered for the whole system. The new approach efficiently mapped out the entire reaction path of ...

  10. Congenital orbital teratoma

    Directory of Open Access Journals (Sweden)

    Shereen Aiyub


    Full Text Available We present a case of mature congenital orbital teratoma managed with lid-sparing exenteration and dermis fat graft. This is a case report on the management of congenital orbital teratoma. A full-term baby was born in Fiji with prolapsed right globe which was surrounded by a nonpulsatile, cystic mass. Clinical and imaging features were consistent with congenital orbital teratoma. Due to limited surgical expertise, the patient was transferred to Adelaide, Australia for further management. The patient underwent a lid-sparing exenteration with frozen section control of the apical margin. A dermis fat graft from the groin was placed beneath the lid skin to provide volume. Histopathology revealed mature tissues from each of the three germ cell layers which confirmed the diagnosis of mature teratoma. We describe the successful use of demis fat graft in socket reconstruction following lid-sparing exenteration for congenital orbital teratoma.

  11. Envelopes of Cometary Orbits

    Directory of Open Access Journals (Sweden)

    Mijajlović, Ž.


    Full Text Available We discuss cometary orbits from the standpoint of Nonstandard (Leibnitz analysis, a relatively new branch of mathematics. In particular, we consider parabolic cometary paths. It appears that, in a sense, every parabola is an ellipse.

  12. The design of a kerosene turbopump for a South African commercial launch vehicle

    CSIR Research Space (South Africa)

    Snedden, Glen C


    Full Text Available hypothetical commercial launch vehicle capable of inserting 50-500kg payloads into 500km sun synchronous orbit. A preliminary design is presented with the focus on the turbopump impeller geometry and its predicted performance....

  13. Orbital interactions in chemistry

    CERN Document Server

    Albright, Thomas A; Whangbo, Myung-Hwan


    Explains the underlying structure that unites all disciplines in chemistry Now in its second edition, this book explores organic, organometallic, inorganic, solid state, and materials chemistry, demonstrating how common molecular orbital situations arise throughout the whole chemical spectrum. The authors explore the relationships that enable readers to grasp the theory that underlies and connects traditional fields of study within chemistry, thereby providing a conceptual framework with which to think about chemical structure and reactivity problems. Orbital Interactions

  14. Is TW Pictoris really an intermediate polar?

    CERN Document Server

    Norton, A J


    We present the results of a long ROSAT HRI observation of the candidate intermediate polar TW Pic. The power spectrum shows no sign of either the previously proposed white dwarf spin period or the proposed binary orbital period (1.996 hr and 6.06 hr respectively). The limits to the X-ray modulation are less than 0.3% in each case. In the absence of a coherent X-ray pulsation, the credentials of TW Pic for membership of the intermediate polar subclass must be suspect. We further suggest that the true orbital period of the binary may be the shorter of the two previously suggested, and that the longer period may represent a quasi-periodic phenomenon associated with the accretion disc.

  15. Antisymmetric Orbit Functions

    Directory of Open Access Journals (Sweden)

    Anatoliy Klimyk


    Full Text Available In the paper, properties of antisymmetric orbit functions are reviewed and further developed. Antisymmetric orbit functions on the Euclidean space $E_n$ are antisymmetrized exponential functions. Antisymmetrization is fulfilled by a Weyl group, corresponding to a Coxeter-Dynkin diagram. Properties of such functions are described. These functions are closely related to irreducible characters of a compact semisimple Lie group $G$ of rank $n$. Up to a sign, values of antisymmetric orbit functions are repeated on copies of the fundamental domain $F$ of the affine Weyl group (determined by the initial Weyl group in the entire Euclidean space $E_n$. Antisymmetric orbit functions are solutions of the corresponding Laplace equation in $E_n$, vanishing on the boundary of the fundamental domain $F$. Antisymmetric orbit functions determine a so-called antisymmetrized Fourier transform which is closely related to expansions of central functions in characters of irreducible representations of the group $G$. They also determine a transform on a finite set of points of $F$ (the discrete antisymmetric orbit function transform. Symmetric and antisymmetric multivariate exponential, sine and cosine discrete transforms are given.

  16. Mesoscopic rings with spin-orbit interactions

    Energy Technology Data Exchange (ETDEWEB)

    Berche, Bertrand; Chatelain, Christophe; Medina, Ernesto, E-mail: berche@lpm.u-nancy.f [Statistical Physics Group, Institut Jean Lamour, UMR CNRS No 7198, Universite Henri Poincare, Nancy 1, B.P. 70239, F-54506 Vandoeuvre les Nancy (France)


    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 currents are derived following an intuitive definition, and then a more thorough derivation is built upon the canonical Lagrangian formulation that emphasizes the SU(2) gauge structure of the transport problem of spin-1/2 fermions in spin-orbit active media. The quantization conditions that follow from the constraint of single-valued Pauli spinors are also discussed. The targeted students are those of a graduate condensed matter physics course.

  17. Metasurface polarization splitter

    CERN Document Server

    Slovick, Brian A; Yu, Zhi Gang; Kravchenckou, Ivan I; Briggs, Dayrl P; Moitra, Parikshit; Krishnamurthy, Srini; Valentine, Jason


    Polarization beam splitters, devices that separate the two orthogonal polarizations of light into different propagation directions, are one of the most ubiquitous optical elements. However, traditionally polarization splitters rely on bulky optical materials, while emerging optoelectronic and photonic circuits require compact, chip-scale polarization splitters. Here we show that a subwavelength rectangular lattice of cylindrical silicon Mie resonators functions as a polarization splitter, efficiently reflecting one polarization while transmitting the other. We show that the polarization splitting arises from the anisotropic permittivity and permeability of the metasurface due to the two-fold rotational symmetry of the rectangular unit cell. The high polarization efficiency, low loss, and low profile make these metasurface polarization splitters ideally suited for monolithic integration with optoelectronic and photonic circuits.

  18. [Orbital complications of sinusitis]. (United States)

    Šuchaň, M; Horňák, M; Kaliarik, L; Krempaská, S; Koštialová, T; Kovaľ, J


    Orbital complications categorised by Chandler are emergency. They need early diagnosis and agresive treatment. Stage and origin of orbital complications are identified by rhinoendoscopy, ophtalmologic examination and CT of orbite and paranasal sinuses. Periorbital cellulitis and early stage of orbital cellulitis can be treated conservatively with i. v. antibiotics. Monitoring of laboratory parameters and ophtalmologic symptoms is mandatory. Lack of improvement or worsening of symptoms within 24-48 hours and advanced stages of orbital complications are indicated for surgery. The purpose of the study is to evaluate epidemiology, clinical features and management of sinogenic orbital complications. Retrospective data of 8 patients with suspicion of orbital complication admited to hospital from 2008 to 2013 were evaluated. Patients were analyzed in terms of gender, age, CT findings, microbiology, clinical features, stage and treatment. Male and female were afected in rate 1,66:1. Most of patients were young adult in 3rd. and 4th. decade of life (62,5 %). Acute and chronic sinusitis were cause of orbital complication in the same rate. The most common origin of orbital complication was ethmoiditis (62,5 %), than maxillary (25 %) and frontal (12,5 %) sinusitis. Polysinusitis with affection of ethmoidal, maxillary and frontal sinuses (75 %) was usual CT finding. Staphylococcus epidermidis and Staphylococcus aureus were etiological agens in half of cases. Periorbital oedema (100 %), proptosis, chemosis (50 %), diplopia and glaucoma (12,5 %) were observed. Based on examinations, diagnosis of periorbital oedema/preseptal cellulitis was made in 3 (37,5 %), orbital cellulitis in 3 (37,5 %) and subperiosteal abscess in 2 cases (25 %). All patients underwent combined therapy - i. v. antibiotics and surgery within 24 hours. Eradication of disease from ostiomeatal complex (OMC), drainage of affected sinuses and drainage of subperiosteal abscess were done via fuctional endonasal

  19. NASA 3D Models: Aquarius (United States)

    National Aeronautics and Space Administration — Aquarius is making NASA's first space-based global observations of ocean surface salinity, flying 657 kilometers (408 miles) above Earth in a sun-synchronous polar...

  20. NMS Flows on Three-Dimensional Manifolds with One Saddle Periodic Orbit

    Institute of Scientific and Technical Information of China (English)



    The simplest NMS flow is a polar flow formed by an attractive periodic orbit and a repulsive periodic orbit as limit sets. In this paper we show that the only orientable, simple, compact,3-dimensional manifolds without boundary that admit an NMS flow with none or one saddle periodic orbit are lens spaces.We also see that when a fattened round handle is a connected sum of tori, the corresponding flow is also a trivial connected sum of flows.

  1. Image Stacking Method Application for Low Earth Orbit Faint Objects (United States)

    Tagawa, M.; Matsumoto, H.; Yanagisawa, T.; Kurosaki, H.; Oda, H.; Kitazawa, Y.; Hanada, T.


    telescopes conduct chasing observation for the estimated apparent trajectory and stack the images based on the relative apparent motion search for true object. Therefore accuracy evaluation for initial orbit estimation result means to verify that apparent motions of true object are able to being searched. The current image stacking method applied for geostationary orbit based on assumptions that apparent motion can be treated as straight lines. Thus the linearity and uniformity assessment of the apparent motion in ground-based tracking observation using initial orbit estimation result is required. This paper introduces the apparent motion prediction result with reasonably assumed orbit estimation errors. The ground observatories are assumed to be located around the polar regions. Then this paper discusses image stacking feasibility for the apparent motion based on space-based orbit estimation result.

  2. Polarized Electron Source Developments

    Energy Technology Data Exchange (ETDEWEB)

    Charles K. Sinclair


    Presently, only two methods of producing beams of polarized electrons for injection into linear accelerators are in use. Each of these methods uses optical pumping by circularly polarized light to produce electron polarization. In one case, electron polarization is established in metastable helium atoms, while in the other case, the polarized electrons are produced in the conduction band of appropriate semiconductors. The polarized electrons are liberated from the helium metastable by chemi-ionization, and from the semiconductors by lowering the work function at the surface of the material. Developments with each of these sources since the 1988 Spin Physics Conference are reviewed, and the prospects for further improvements discussed.

  3. Geographical Income Polarization

    DEFF Research Database (Denmark)

    Azhar, Hussain; Jonassen, Anders Bruun

    In this paper we estimate the degree, composition and development of geographical income polarization based on data at the individual and municipal level in Denmark from 1984 to 2002. Rising income polarization is reconfirmed when applying new polarization measures, the driving force being greater...... inter municipal income inequality. Counter factual simulations show that rising property prices to a large part explain the rise in polarization. One side-effect of polarization is tendencies towards a parallel polarization of residence location patterns, where low skilled individuals tend to live...

  4. Polarization in exoplanetary systems caused by transits, grazing transits, and starspots

    CERN Document Server

    Kostogryz, N M; Berdyugina, S V


    We present results of numerical simulations of flux and linear polarization variations in transiting exoplanetary systems, caused by the host star disk symmetry breaking. We consider different configurations of planetary transits depending on orbital parameters. Starspot contribution to the polarized signal is also estimated. Applying the method to known systems and simulating observational conditions, a number of targets is selected where transit polarization effects could be detected. We investigate several principal benefits of the transit polarimetry, particularly, for determining orbital spatial orientation and distinguishing between grazing and near-grazing planets. Simulations show that polarization parameters are also sensitive to starspots, and they can be used to determine spot positions and sizes.

  5. Electron correlation by polarization of interacting densities

    CERN Document Server

    Whitten, Jerry L


    Coulomb interactions that occur in electronic structure calculations are correlated by allowing basis function components of the interacting densities to polarize, thereby reducing the magnitude of the interaction. Exchange integrals of molecular orbitals are not correlated. The modified Coulomb interactions are used in single-determinant or configuration interaction calculations. The objective is to account for dynamical correlation effects without explicitly introducing higher spherical harmonic functions into the molecular orbital basis. Molecular orbital densities are decomposed into a distribution of spherical components that conserve the charge and each of the interacting components is considered as a two-electron wavefunction embedded in the system acted on by an average field Hamiltonian plus . A method of avoiding redundancy is described. Applications to atoms, negative ions and molecules representing different types of bonding and spin states are discussed.

  6. Orbit Propagation and Determination of Low Earth Orbit Satellites


    Ho-Nien Shou


    This paper represents orbit propagation and determination of low Earth orbit (LEO) satellites. Satellite global positioning system (GPS) configured receiver provides position and velocity measures by navigating filter to get the coordinates of the orbit propagation (OP). The main contradictions in real-time orbit which is determined by the problem are orbit positioning accuracy and the amount of calculating two indicators. This paper is dedicated to solving the problem of tradeoffs. To plan t...

  7. Orbits for sixteen binaries

    Directory of Open Access Journals (Sweden)

    Cvetković Z.


    Full Text Available In this paper orbits for 13 binaries are recalculated and presented. The reason is that recent observations show higher residuals than the corresponding ephemerides calculated by using the orbital elements given in the Sixth Catalog of Orbits of Visual Binary Stars. The binaries studied were: WDS 00182+7257 = A 803, WDS 00335+4006 = HO 3, WDS 00583+2124 = BU 302, WDS 01011+6022 = A 926, WDS 01014+1155 = BU 867, WDS 01112+4113 = A 655, WDS 01361−2954 + HJ 3447, WDS 02333+5219 = STT 42 AB,WDS 04362+0814 = A 1840 AB,WDS 08017−0836 = A 1580, WDS 08277−0425 = A 550, WDS 17471+1742 = STF 2215 and WDS 18025+4414 = BU 1127 Aa-B. In addition, for three binaries - WDS 01532+1526 = BU 260, WDS 02563+7253 = STF 312 AB and WDS 05003+3924 = STT 92 AB - the orbital elements are calculated for the first time. In this paper the authors present not only the orbital elements, but the masses dynamical parallaxes, absolute magnitudes and ephemerides for the next five years, as well.

  8. Orbital Fluid Resupply Assessment (United States)

    Eberhardt, Ralph N.


    Orbital fluid resupply can significantly increase the cost-effectiveness and operational flexibility of spacecraft, satellites, and orbiting platforms and observatories. Reusable tankers are currently being designed for transporting fluids to space. A number of options exist for transporting the fluids and propellant to the space-based user systems. The fluids can be transported to space either in the Shuttle cargo bay or using expendable launch vehicles (ELVs). Resupply can thus be accomplished either from the Shuttle bay, or the tanker can be removed from the Shuttle bay or launched on an ELV and attached to a carrier such as the Orbital Maneuvering Vehicle (OMV) or Orbital Transfer Vehicle (OTV) for transport to the user to be serviced. A third option involves locating the tanker at the space station or an unmanned platform as a quasi-permanent servicing facility or depot which returns to the ground for recycling once its tanks are depleted. Current modular tanker designs for monopropellants, bipropellants, and water for space station propulsion are discussed. Superfluid helium tankers are addressed, including trade-offs in tanker sizes, shapes to fit the range of ELVs currently available, and boil-off losses associated with longer-term (greater than 6-month) space-basing. It is concluded that the mixed fleet approach to on-orbit consumables resupply offers significant advantages to the overall logistics requirements.

  9. Polarized Raman optical activity of menthol and related molecules (United States)

    Barron, L. D.; Hecht, L.; Blyth, S. M.


    Polarized and depolarized Raman optical activity spectra of menthol, menthyl chloride, neomenthol and neothiomenthol from 800 to 1500 cm -1 are reported. Despite axial symmetry in all the bonds, the presence of the heteroatoms O or S seems to induce large deviations from the expected ratio of 2:1 between the polarized and depolarized Raman optical activity intensities, but Cl does not. These deviations might originate in large electric quadrupole contributions induced by excited state interactions involving O or S Rydberg p orbitals and valence orbitals on other parts of the molecule. Such interactions appear to undermine the bond polarizability theory of Raman intensities.

  10. Do observations reveal accretion discs in intermediate polars

    Energy Technology Data Exchange (ETDEWEB)

    Hellier, C. (University Coll., London (UK). Mullard Space Science Lab.)


    It has been proposed that intermediate polars do not accrete through discs and that they may not possess discs. Observations of eclipses and emission lines provide strong evidence that discs are present in many intermediate polars, although it is less clear whether the accretion flows through these discs. An analysis of the EXOSAT database shows that many systems have orbital and beat period modulations which are small compared to the spin-pulses, suggesting disc accretion. There are, though, exceptions, notably TX Col where dominant orbital and beat period modulations indicate discless accretion. (author).

  11. How Thick is the North Polar Ice Cap on Mars? (United States)


    This map shows the thickness of the north polar layered deposits on Mars as measured by the Shallow Radar instrument on NASA's Mars Reconnaissance Orbiter. The Shallow Radar instrument was provided by the Italian Space Agency. Its operations are led by the University of Rome and its data are analyzed by a joint U.S.-Italian science team. JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter for the NASA Science Mission Directorate, Washington

  12. How Thick is the North Polar Ice Cap on Mars? (United States)


    This map shows the thickness of the north polar layered deposits on Mars as measured by the Shallow Radar instrument on NASA's Mars Reconnaissance Orbiter. The Shallow Radar instrument was provided by the Italian Space Agency. Its operations are led by the University of Rome and its data are analyzed by a joint U.S.-Italian science team. JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter for the NASA Science Mission Directorate, Washington

  13. Extended duration orbiter (EDO) insignia (United States)


    Extended duration orbiter (EDO) insignia incorporates a space shuttle orbiter with payload bay doors (PLBDs) open and a spacelab module inside. Trailing the orbiter are the initials EDO. The EDO-modified Columbia, Orbiter Vehicle (OV) 102, will be flown for the first EDO mission, STS-50.

  14. Spin polarization of electrons with Rashba double-refraction

    Energy Technology Data Exchange (ETDEWEB)

    Ramaglia, V Marigliano; Bercioux, D; Cataudella, V; De Filippis, G; Perroni, C A [Coherentia-INFM and Dipartimento di Scienze Fisiche Universita degli Studi Federico II, Naples, I-80126 (Italy)


    We demonstrate how the Rashba spin-orbit coupling in semiconductor heterostructures can produce and control a spin-polarized current without ferromagnetic leads. The key idea is to use spin-double refraction of an electronic beam with a nonzero incidence angle. A region where the spin-orbit coupling is present separates the source and the drain without spin-orbit coupling. We show how the transmission and the beam spin polarization critically depend on the incidence angle. The transmission halves when the incidence angle is greater than a limit angle and a significant spin polarization appears. On increasing the spin-orbit coupling one can obtain the modulation of the intensity and of the spin polarization of the output electronic current when the input current is unpolarized. Our analysis shows the possibility of realizing a spin-field-effect transistor based on the propagation of only one mode with the region with spin-orbit coupling, whereas the original Datta and Das device (1990 Appl. Phys. Lett. 56 665) uses the spin precession that originates from the interference between two modes with orthogonal spin.

  15. LROC - Lunar Reconnaissance Orbiter Camera (United States)

    Robinson, M. S.; Eliason, E.; Hiesinger, H.; Jolliff, B. L.; McEwen, A.; Malin, M. C.; Ravine, M. A.; Thomas, P. C.; Turtle, E. P.


    The Lunar Reconnaissance Orbiter (LRO) went into lunar orbit on 23 June 2009. The LRO Camera (LROC) acquired its first lunar images on June 30 and commenced full scale testing and commissioning on July 10. The LROC consists of two narrow-angle cameras (NACs) that provide 0.5 m scale panchromatic images over a combined 5 km swath, and a wide-angle camera (WAC) to provide images at a scale of 100 m per pixel in five visible wavelength bands (415, 566, 604, 643, and 689 nm) and 400 m per pixel in two ultraviolet bands (321 nm and 360 nm) from the nominal 50 km orbit. Early operations were designed to test the performance of the cameras under all nominal operating conditions and provided a baseline for future calibrations. Test sequences included off-nadir slews to image stars and the Earth, 90° yaw sequences to collect flat field calibration data, night imaging for background characterization, and systematic mapping to test performance. LRO initially was placed into a terminator orbit resulting in images acquired under low signal conditions. Over the next three months the incidence angle at the spacecraft’s equator crossing gradually decreased towards high noon, providing a range of illumination conditions. Several hundred south polar images were collected in support of impact site selection for the LCROSS mission; details can be seen in many of the shadows. Commissioning phase images not only proved the instruments’ overall performance was nominal, but also that many geologic features of the lunar surface are well preserved at the meter-scale. Of particular note is the variety of impact-induced morphologies preserved in a near pristine state in and around kilometer-scale and larger young Copernican age impact craters that include: abundant evidence of impact melt of a variety of rheological properties, including coherent flows with surface textures and planimetric properties reflecting supersolidus (e.g., liquid melt) emplacement, blocks delicately perched on

  16. Climatic changes on orbital and sub-orbital time scale recorded by the Guliya ice core in Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    姚檀栋; 徐柏青; 蒲健辰


    Based on ice core records in the Tibetan Plateau and Greenland, the features and possible causes of climatic changes on orbital and sub-orbital time scale were discussed. Orbital time scale climatic change recorded in ice core from the Tibetan Plateau is typically ahead of that from polar regions, which indicates that climatic change in the Tibetan Plateau might be earlier than polar regions. The solar radiation change is a major factor that dominates the climatic change on orbital time scale. However, climatic events on sub-orbital time scale occurred later in the Tibetan Plateau than in the Arctic Region, indicating a different mechanism. For example, the Younger Dryas and Heinrich events took place earlier in Greenland ice core record than in Guliya ice core record. It is reasonable to propose the hypothesis that these climatic events were affected possibly by the Laurentide Ice Sheet. Therefore, ice sheet is critically important to climatic change on sub-orbital time scale in some ice ages.

  17. Polarization phenomena in hyperon-nucleon scattering

    CERN Document Server

    Ishikawa, S; Iseri, Y; Yamamoto, Y


    We investigate polarization observables in hyperon-nucleon scattering by decomposing scattering amplitudes into spin-space tensors, where each component describes scattering by corresponding spin-dependent interactions, so that contributions of the interactions in the observables are individually identified. In this way, for elastic scattering we find some linear combinations of the observables sensitive to particular spin-dependent interactions such as symmetric spin-orbit (LS) interactions and antisymmetric LS ones. These will be useful to criticize theoretical predictions of the interactions when the relevant observables are measured. We treat vector analyzing powers, depolarizations, and coefficients of polarization transfers and spin correlations, a part of which is numerically examined in $\\Sigma^{+} p$ scattering as an example. Total cross sections are studied for polarized beams and targets as well as for unpolarized ones to investigate spin dependence of imaginary parts of forward scattering amplitud...

  18. A Translational Polarization Rotator

    CERN Document Server

    Chuss, David T; Pisano, Giampaolo; Ackiss, Sheridan; U-Yen, Kongpop; Ng, Ming wah


    We explore a free-space polarization modulator in which a variable phase introduction between right- and left-handed circular polarization components is used to rotate the linear polarization of the outgoing beam relative to that of the incoming beam. In this device, the polarization states are separated by a circular polarizer that consists of a quarter-wave plate in combination with a wire grid. A movable mirror is positioned behind and parallel to the circular polarizer. As the polarizer-mirror distance is separated, an incident linear polarization will be rotated through an angle that is proportional to the introduced phase delay. We demonstrate a prototype device that modulates Stokes Q and U over a 20% bandwidth.

  19. Polarized Light Corridor Demonstrations. (United States)

    Davies, G. R.


    Eleven demonstrations of light polarization are presented. Each includes a brief description of the apparatus and the effect demonstrated. Illustrated are strain patterns, reflection, scattering, the Faraday Effect, interference, double refraction, the polarizing microscope, and optical activity. (CW)

  20. NESDIS VIIRS Polar Winds (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains the Level 3 Polar Winds Northern and Southern Hemisphere datasets. The Level 3 Polar Winds data from VIIRS for the Arctic and Antarctic from 65...

  1. Vertical orbital dystopia. (United States)

    Tan, S T; Ashworth, G; Czypionka, S; Poole, M D; Briggs, M


    Many pathologic processes may lead to vertical orbital dystopia. We reviewed 47 consecutive cases seen over a 13-year period. Twenty-nine patients underwent eye leveling procedures to improve cosmesis, 2 of these by camouflage procedures and 27 by orbital translocation. Ten patients had 16 secondary operations. There was one death, serious complications occurred in 3 patients, and nuisance complications occurred in 20 others. Seven patients developed diplopia postoperatively, and in 6 patients it was troublesome. In these, it resolved fully in 2 patients, improved to be of no consequence in 2, and in the remaining 2 troublesome symptoms persisted requiring inferior oblique muscle recession in 1. Binocular vision was never restored when not present preoperatively, and in 3 patients temporary loss occurred. There was an overall modest but significant improvement in appearance after surgery. It is concluded that vertical orbital translocation is rewarding and worthwhile.

  2. Deceleration Orbit Improvements

    Energy Technology Data Exchange (ETDEWEB)

    Church, M.


    During the accelerator studies period of 12/90-1/91 much study time was dedicated to improving the E760 deceleration ramps. 4 general goals were in mind: (1) Reduce the relative orbit deviations from the nominal reference orbit as much as possible. This reduces the potential error in the orbit length calculation - which is the primary source of error in the beam energy calculation. (2) Maximize the transverse apertures. This minimizes beam loss during deceleration and during accidental beam blow-ups. (3) Measure and correct lattice parameters. Knowledge of {gamma}{sub T}, {eta}, Q{sub h}, Q{sub v}, and the dispersion in the straight sections allows for a more accurate energy calculation and reliable SYNCH calculations. (4) Minimize the coupling. This allows one to discern between horizontal and vertical tunes.

  3. [Secondary orbital lymphoma]. (United States)

    Basanta, I; Sevillano, C; Álvarez, M D


    A case is presented of an 85 year-old Caucasian female with lymphoma that recurred in the orbit (secondary ocular adnexal lymphoma). The orbital tumour was a diffuse large B-cell lymphoma according to the REAL classification (Revised European-American Lymphoma Classification). Orbital lymphomas are predominantly B-cell proliferations of a variety of histological types, and most are low-grade tumours. Patients are usually middle-aged or elderly, and it is slightly more common in women. A palpable mass, proptosis and blepharoptosis are the most common signs of presentation. Copyright © 2011 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  4. Experimental observation of polarization-dependent optical vortex beams

    CERN Document Server

    Srisuphaphon, S; Photia, T; Temnuch, W; Chiangga, S; Deachapunya, S


    We report the experimental demonstration of the induced polarization-dependent optical vortex beams. We use the Talbot configuration as a method to probe this effect. In particular, our simple experiment shows the direct measurement of this observation. Our experiment can exhibit clearly the combination between the polarization and orbital angular momentum (OAM) states of light. This implementation might be useful for further studies in the quantum system or quantum information.

  5. SELENE: The Moon-Orbiting Observatory Mission (United States)

    Mizutani, H.; Kato, M.; Sasaki, S.; Iijima, Y.; Tanaka, K.; Takizawa, Y.

    The Moon-orbiting SELENE (Selenological and Engineering Explorer) mission is prepared in Japan for lunar science and technology development. The launch target has been changed from 2005 to 2006 because of the launch failure of H2A rocket in 2003. The spacecraft consists of a main orbiting satellite at about 100 km altitude in the polar orbit and two sub-satellites in the elliptical orbits. The scientific objectives of the mission are; 1) study of the origin and evolution of the Moon, 2) in-situ measurement of the lunar environment, and 3) observation of the solar-terrestrial plasma environment. SELENE carries the instruments for scientific investigation, including mapping of lunar topography and surface composition, measurement of the gravity and magnetic fields, and observation of lunar and solar-terrestrial plasma environment. The total mass of scientific payload is about 300 kg. The mission period will be 1 year. If extra fuel is available, the mission will be extended in a lower orbit around 50 km. The elemental abundances are measured by x-ray and gamma-ray spectrometers. Alpha particles from the radon gas and polonium are detected by an alpha particle spectrometer. The mineralogical abundance is characterized by a multi-band imager. The mineralogical composition is identified by a spectral profiler which is a continuous spectral analyzer. The surface topographic data are obtained by a high resolution terrain camera and a laser altimeter. The inside structure up to 5 km below the lunar surface is observed by the radar sounder experiment using a 5 MHz radio wave. A magnetometer and an electron reflectometer provides data on the lunar surface magnetic field. Doppler tracking of the orbiter via the sub-satellite when the orbiter is in the far side is used to determine the gravity field of the far side. Radio sources on the two sub-satellites are used to conduct differential VLBI observation from the ground stations. The lunar environment of high energy particles

  6. Optical orbital angular momentum (United States)

    Barnett, Stephen M.; Babiker, Mohamed; Padgett, Miles J.


    We present a brief introduction to the orbital angular momentum of light, the subject of our theme issue and, in particular, to the developments in the 13 years following the founding paper by Allen et al. (Allen et al. 1992 Phys. Rev. A 45, 8185 (doi:10.1103/PhysRevA.45.8185)). The papers by our invited authors serve to bring the field up to date and suggest where developments may take us next. This article is part of the themed issue ‘Optical orbital angular momentum’. PMID:28069775

  7. Optical orbital angular momentum (United States)

    Barnett, Stephen M.; Babiker, Mohamed; Padgett, Miles J.


    We present a brief introduction to the orbital angular momentum of light, the subject of our theme issue and, in particular, to the developments in the 13 years following the founding paper by Allen et al. (Allen et al. 1992 Phys. Rev. A 45, 8185 (doi:10.1103/PhysRevA.45.8185)). The papers by our invited authors serve to bring the field up to date and suggest where developments may take us next. This article is part of the themed issue 'Optical orbital angular momentum'.

  8. Plasma polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Takashi [Department of Engineering Physics and Mechanics, Graduate School of Engineering, Kyoto University, Kyoto (Japan)


    Polarization of radiation emitted from a plasma reflects the anisotropic properties of the plasma, especially the angular anisotropic distribution of electron velocities. Polarization has been observed on impurity ion lines from the WT-3 tokamak and the GAMMA-10 tandem mirror machines. The soft x-ray laser line from the neonlike germanium was also found polarized. (author)

  9. Polarity at Many Levels (United States)

    Flannery, Maura C.


    An attempt is made to find how polarity arises and is maintained, which is a central issue in development. It is a fundamental attribute of living things and cellular polarity is also important in the development of multicellular organisms and controversial new work indicates that polarization in mammals may occur much earlier than previously…

  10. Geographical Income Polarization

    DEFF Research Database (Denmark)

    Azhar, Hussain; Jonassen, Anders Bruun

    In this paper we estimate the degree, composition and development of geographical income polarization based on data at the individual and municipal level in Denmark from 1984 to 2002. Rising income polarization is reconfirmed when applying new polarization measures, the driving force being greater...

  11. Graphing Polar Curves (United States)

    Lawes, Jonathan F.


    Graphing polar curves typically involves a combination of three traditional techniques, all of which can be time-consuming and tedious. However, an alternative method--graphing the polar function on a rectangular plane--simplifies graphing, increases student understanding of the polar coordinate system, and reinforces graphing techniques learned…

  12. Stability of orbits around planetary satellites considering a disturbing body in an elliptical orbit: Applications to Europa and Ganymede (United States)

    Cardoso dos Santos, Josué; Carvalho, Jean Paulo; Vilhena de Moraes, Rodolpho

    Europa and Ganymede are two of the four Jupiter’s moons which compose the Galilean satellite. These ones are planetary satellites of greater interest at the present moment among the scientific community. There are some missions being planned to visit them and and the Jovian system. One of them is the cooperation between NASA and ESA for the Europa Jupiter System Mission (EJSM). In this mission are planned the insertion of the spacecrafts JEO (Jupiter Europa Orbiter) and JGO (Jupiter Ganymede Orbiter) into Europa and Ganymede’s orbit. Thus, there is a great necessity for having a better comprehension of the dynamics of the orbits around this planetary satellite. This comprehension is essential for the success of this type of mission. In this context, this work aims to perform a search for low-altitude orbits around these planetary satellites. An emphasis is given in polar orbits. These orbits can be useful in the planning of aerospace activities to be conducted around this planetary satellite, with respect to the stability of orbits of artificial satellites. The study considers orbits of an artificial satellite around Europa and Ganymede under the influence of the third-body perturbation (the gravitational attraction of Jupiter) and the polygenic perturbations. These last ones occur due to forces such as the non-uniform distribution of mass (J2 and J3) of the main (central) body. A simplified dynamic model for polygenic perturbations is used. A new model for the third-body disturbance is presented considering it in an elliptical orbit. The Lagrange planetary equations, which compose a system of nonlinear differential equations, are used to describe the orbital motion of the artificial satellite around Ganymede. The equations showed here are developed in closed form to avoid expansions in inclination and eccentricity.

  13. Local orbitals by minimizing powers of the orbital variance

    DEFF Research Database (Denmark)

    Jansik, Branislav; Høst, Stinne; Kristensen, Kasper;


    It is demonstrated that a set of local orthonormal Hartree–Fock (HF) molecular orbitals can be obtained for both the occupied and virtual orbital spaces by minimizing powers of the orbital variance using the trust-region algorithm. For a power exponent equal to one, the Boys localization function...... is obtained. For increasing power exponents, the penalty for delocalized orbitals is increased and smaller maximum orbital spreads are encountered. Calculations on superbenzene, C60, and a fragment of the titin protein show that for a power exponent equal to one, delocalized outlier orbitals may...

  14. The impact of orbital sampling, monthly averaging and vertical resolution on climate chemistry model evaluation with satellite observations

    Directory of Open Access Journals (Sweden)

    A. M. Aghedo


    Full Text Available Ensemble climate model simulations used for the Intergovernmental Panel on Climate Change (IPCC assessments have become important tools for exploring the response of the Earth System to changes in anthropogenic and natural forcings. The systematic evaluation of these models through global satellite observations is a critical step in assessing the uncertainty of climate change projections. This paper presents the technical steps required for using nadir sun-synchronous infrared satellite observations for multi-model evaluation and the uncertainties associated with each step. This is motivated by need to use satellite observations to evaluate climate models. We quantified the implications of the effect of satellite orbit and spatial coverage, the effect of variations in vertical sensitivity as quantified by the observation operator and the impact of averaging the operators for use with monthly-mean model output. We calculated these biases in ozone, carbon monoxide, atmospheric temperature and water vapour by using the output from two global chemistry climate models (ECHAM5-MOZ and GISS-PUCCINI and the observations from the Tropospheric Emission Spectrometer (TES instrument on board the NASA-Aura satellite from January 2005 to December 2008.

    The results show that sampling and monthly averaging of the observation operators produce zonal-mean biases of less than ±3 % for ozone and carbon monoxide throughout the entire troposphere in both models. Water vapour sampling zonal-mean biases were also within the insignificant range of ±3 % (that is ±0.14 g kg−1 in both models. Sampling led to a temperature zonal-mean bias of ±0.3 K over the tropical and mid-latitudes in both models, and up to −1.4 K over the boundary layer in the higher latitudes. Using the monthly average of temperature and water vapour operators lead to large biases over the boundary layer in the southern-hemispheric higher latitudes and in the upper

  15. The impact of orbital sampling, monthly averaging and vertical resolution on climate chemistry model evaluation with satellite observations

    Directory of Open Access Journals (Sweden)

    A. M. Aghedo


    Full Text Available Ensemble climate model simulations used for the Intergovernmental Panel on Climate Change (IPCC assessments have become important tools for exploring the response of the Earth System to changes in anthropogenic and natural forcings. The systematic evaluation of these models through global satellite observations is a critical step in assessing the uncertainty of climate change projections. This paper presents the technical steps required for using nadir sun-synchronous infrared satellite observations for multi-model evaluation and the uncertainties associated with each step. This is motivated by need to use satellite observations to evaluate climate models. We quantified the implications of the effect of satellite orbit and spatial coverage, the effect of variations in vertical sensitivity as quantified by the observation operator and the impact of averaging the operators for use with monthly-mean model output. We calculated these biases in ozone, carbon monoxide, atmospheric temperature and water vapour by using the output from two global chemistry climate models (ECHAM5-MOZ and GISS-PUCCINI and the observations from the Tropospheric Emission Spectrometer (TES satellite from January 2005 to December 2008.

    The results show that sampling and monthly averaging of the observation operators produce biases of less than ±3% for ozone and carbon monoxide throughout the entire troposphere in both models. Water vapour sampling biases were also within the insignificant range of ±3% (that is ±0.14 g kg−1 in both models. Sampling led to a temperature bias of ±0.3 K over the tropical and mid-latitudes in both models, and up to −1.4 K over the boundary layer in the higher latitudes. Using the monthly average of temperature and water vapour operators lead to large biases over the boundary layer in the southern-hemispheric higher latitudes and in the upper troposphere, respectively. Up to 8% bias was calculated in the upper

  16. Summary of the results from the lunar orbiter laser altimeter after seven years in lunar orbit (United States)

    Smith, David E.; Zuber, Maria T.; Neumann, Gregory A.; Mazarico, Erwan; Lemoine, Frank G.; Head, James W., III; Lucey, Paul G.; Aharonson, Oded; Robinson, Mark S.; Sun, Xiaoli; Torrence, Mark H.; Barker, Michael K.; Oberst, Juergen; Duxbury, Thomas C.; Mao, Dandan; Barnouin, Olivier S.; Jha, Kopal; Rowlands, David D.; Goossens, Sander; Baker, David; Bauer, Sven; Gläser, Philipp; Lemelin, Myriam; Rosenburg, Margaret; Sori, Michael M.; Whitten, Jennifer; Mcclanahan, Timothy


    In June 2009 the Lunar Reconnaissance Orbiter (LRO) spacecraft was launched to the Moon. The payload consists of 7 science instruments selected to characterize sites for future robotic and human missions. Among them, the Lunar Orbiter Laser Altimeter (LOLA) was designed to obtain altimetry, surface roughness, and reflectance measurements. The primary phase of lunar exploration lasted one year, following a 3-month commissioning phase. On completion of its exploration objectives, the LRO mission transitioned to a science mission. After 7 years in lunar orbit, the LOLA instrument continues to map the lunar surface. The LOLA dataset is one of the foundational datasets acquired by the various LRO instruments. LOLA provided a high-accuracy global geodetic reference frame to which past, present and future lunar observations can be referenced. It also obtained high-resolution and accurate global topography that were used to determine regions in permanent shadow at the lunar poles. LOLA further contributed to the study of polar volatiles through its unique measurement of surface brightness at zero phase, which revealed anomalies in several polar craters that may indicate the presence of water ice. In this paper, we describe the many LOLA accomplishments to date and its contribution to lunar and planetary science.

  17. Tunable all electric spin polarizer (United States)

    Bhandari, Nikhil K.

    To realize the full potential of spin-based devices, ways must be found to inject, manipulate, and detect the spin of the electron by purely electrical means. Previously, our group has shown that a quantum point contact (QPC) with lateral spin orbit coupling (LSOC) can be used to create a strongly spin-polarized current by purely electrical means. The LSOC results from the lateral in-plane electric field created by the confining potential in QPCs with in-plane side gates (SGs). Strongly spin-polarized currents can be generated by tuning the asymmetric bias voltages on the side gates. A conductance anomaly in the form of a plateau at conductance G ≅ 0.5G0 (where G 0 = 2e2/h) was observed in the ballistic conductance of a QPC based in the absence of magnetic field - which was established to be a signature of complete spin polarization. A Non-Equilibrium Green's Function (NEGF) analysis was used to model a small QPC and three ingredients were found to be essential to generate a strong spin polarization: (1) LSOC, (2) an asymmetric lateral confinement, and (3) a strong electron-electron (e-e) interaction. We have also shown that all-electric control of spin polarization can be achieved for different materials, electron mobility, heterostructure design, QPC dimensions and strength of LSOC. Our previous experimental and theoretical results have also found the presence of other conductance anomalies (i.e., at values different from 0.5 G0 ) and the main reason for these occurrences was shown to be due to the influence of surface roughness scattering. In this thesis, we address the important technological challenge to better control the location of the conductance anomalies in QPCs and create a tunable all-electric spin polarizer based on a QPC with four gates, i.e., with two in-plane SGs in series. Here, the first pair of SGs, near the source, is asymmetrically biased to create spin polarization in the QPC channel. The second set of gates, near the drain, is

  18. Solar Orbiter Status Report (United States)

    Gilbert, Holly; St. Cyr, Orville Chris; Mueller, Daniel; Zouganelis, Yannis; Velli, Marco


    With the delivery of the instruments to the spacecraft builder, the Solar Orbiter mission is in the midst of Integration & Testing phase at Airbus in Stevenage, U.K. This mission to “Explore the Sun-Heliosphere Connection” is the first medium-class mission of ESA’s Cosmic Vision 2015-2025 program and is being jointly implemented with NASA. The dedicated payload of 10 remote-sensing and in-situ instruments will orbit the Sun as close as 0.3 A.U. and will provide measurments from the photosphere into the solar wind. The three-axis stabilized spacecraft will use Venus gravity assists to increase the orbital inclination out of the ecliptic to solar latitudes as high as 34 degrees in the extended mission. The science team of Solar Orbiter has been working closely with the Solar Probe Plus scientists to coordinate observations between these two highly-complementary missions. This will be a status report on the mission development; the interested reader is referred to the recent summary by Müller et al., Solar Physics 285 (2013).

  19. Sedna Orbit Animation (United States)


    This animation shows the location of the newly discovered planet-like object, dubbed 'Sedna,' in relation to the rest of the solar system. Starting at the inner solar system, which includes the orbits of Mercury, Venus, Earth, and Mars (all in yellow), the view pulls away through the asteroid belt and the orbits of the outer planets beyond (green). Pluto and the distant Kuiper Belt objects are seen next until finally Sedna comes into view. As the field widens the full orbit of Sedna can be seen along with its current location. Sedna is nearing its closest approach to the Sun; its 10,000 year orbit typically takes it to far greater distances. Moving past Sedna, what was previously thought to be the inner edge of the Oort cloud appears. The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than scientists believed.

  20. Myxoma of the orbit.

    Directory of Open Access Journals (Sweden)

    Rambhatla Saptagirish


    Full Text Available Myxomas are rare, benign neoplasms of mesenchymal origin that usually develop in soft tissues. As the clinical manifestations are non-specific, it is difficult to diagnose the tumour without biopsy and histopathological examination. We report a case of orbital myxoma with histopathological correlation.

  1. Sedna Orbit Animation (United States)


    This animation shows the location of the newly discovered planet-like object, dubbed 'Sedna,' in relation to the rest of the solar system. Starting at the inner solar system, which includes the orbits of Mercury, Venus, Earth, and Mars (all in yellow), the view pulls away through the asteroid belt and the orbits of the outer planets beyond (green). Pluto and the distant Kuiper Belt objects are seen next until finally Sedna comes into view. As the field widens the full orbit of Sedna can be seen along with its current location. Sedna is nearing its closest approach to the Sun; its 10,000 year orbit typically takes it to far greater distances. Moving past Sedna, what was previously thought to be the inner edge of the Oort cloud appears. The Oort cloud is a spherical distribution of cold, icy bodies lying at the limits of the Sun's gravitational pull. Sedna's presence suggests that this Oort cloud is much closer than scientists believed.

  2. Inertial effect on spin–orbit coupling and spin transport

    Energy Technology Data Exchange (ETDEWEB)

    Basu, B., E-mail:; Chowdhury, Debashree, E-mail:


    We theoretically study the renormalization of inertial effects on the spin dependent transport of conduction electrons in a semiconductor by taking into account the interband mixing on the basis of k{sup →}⋅p{sup →} perturbation theory. In our analysis, for the generation of spin current we have used the extended Drude model where the spin–orbit coupling plays an important role. We predict enhancement of the spin current resulting from the renormalized spin–orbit coupling effective in our model in cubic and non-cubic crystals. Attention has been paid to clarify the importance of gauge fields in the spin transport of this inertial system. A theoretical proposition of a perfect spin filter has been done through the Aharonov–Casher like phase corresponding to this inertial system. For a time dependent acceleration, effect of k{sup →}⋅p{sup →} perturbation on the spin current and spin polarization has also been addressed. Furthermore, achievement of a tunable source of polarized spin current through the non uniformity of the inertial spin–orbit coupling strength has also been discussed. -- Highlights: •Study of the renormalization of inertial spin dependent transport of electrons. •Enhancement of the spin current due to the renormalized spin–orbit coupling. •A theoretical proposition of a perfect spin filter. •For a time dependent acceleration, spin current, spin polarization is addressed.

  3. The effect of gravitational spin-orbit coupling on the circular photon orbit in the Schwarzschild geometry

    CERN Document Server

    Wang, Zhi-Yong; Qiu, Qi; Wang, Yun-Xiang; Shi, Shuang-Jin


    The (1, 0)+(0, 1) representation of the group SL(2, C) provides a six-component spinor equivalent to the electromagnetic field tensor. By means of the (1, 0)+(0, 1) description, one can treat the photon field in curved spacetime via spin connection and the tetrad formalism, which is of great advantage to study the gravitational spin-orbit coupling of photons. Once the gravitational spin-orbit coupling is taken into account, the traditional radius of the circular photon orbit in the Schwarzschild geometry should be replaced with two different radiuses corresponding to the photons with the helicities of +1 and -1, respectively. Owing to the splitting of energy levels induced by the spin-orbit coupling, photons (from Hawking radiations, say) escaping from a Schwarzschild black hole are partially polarized, provided that their initial velocities possess nonzero tangential components.

  4. The Physics of Polarization (United States)

    Landi Degl'Innocenti, Egidio


    The introductory lecture that has been delivered at this Symposium is a condensed version of an extended course held by the author at the XII Canary Island Winter School from November 13 to November 21, 2000. The full series of lectures can be found in Landi Degl'Innocenti (2002). The original reference is organized in 20 Sections that are here itemized: 1. Introduction, 2. Description of polarized radiation, 3. Polarization and optical devices: Jones calculus and Muller matrices, 4. The Fresnel equations, 5. Dichroism and anomalous dispersion, 6. Polarization in everyday life, 7. Polarization due to radiating charges, 8. The linear antenna, 9. Thomson scattering, 10. Rayleigh scattering, 11. A digression on Mie scattering, 12. Bremsstrahlung radiation, 13. Cyclotron radiation, 14. Synchrotron radiation, 15. Polarization in spectral lines, 16. Density matrix and atomic polarization, 17. Radiative transfer and statistical equilibrium equations, 18. The amplification condition in polarized radiative transfer, and 19. Coupling radiative transfer and statistical equilibrium equations.

  5. Polarization effects. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Courant, E.


    The use of polarized proton beams in ISABELLE is important for several general reasons: (1) With a single longitudinally polarized proton beam, effects involving parity violation can be identified and hence processes involving weak interactions can be separated from those involving strong and electromagnetic interactions. (2) Spin effects are important in the strong interactions and can be useful for testing QCD. The technique for obtaining polarized proton beams in ISABELLE appears promising, particularly in view of the present development of a polarized proton beam for the AGS. Projections for the luminosity in ISABELLE for collisions of polarized protons - one or both beams polarized with longitudinal or transverse polarization - range from 1/100 to 1 times the luminosity for unpolarized protons.

  6. Polarity inversion in polar-nonpolar-polar heterostructures. (United States)

    Cho, S; Youn, S J; Kim, Y; DiVenere, A; Wong, G K; Freeman, A J; Ketterson, J B


    We have observed an epilayer-thickness-dependent polarity inversion for the growth of CdTe on Sb(Bi)/CdTe(111)B. For films with Sb(Bi) thicknesses of less than 40 A (15 A), the CdTe layer shows a B (Te-terminated) face, but it switches to an A (Cd-terminated) face for thicker layers. On the other hand, a CdTe layer grown on Bi(Sb)/CdTe(111)A always shows the A face regardless of Sb or Bi layer thicknesses. In order to address the observations we have performed ab initio calculations, which suggest that the polarity of a polar material on a nonpolar one results from the binding energy difference between the two possible surface configurations.

  7. Polarized QPOs from the INTEGRAL polar IGRJ14536-5522 (=Swift J1453.4-5524)

    CERN Document Server

    Potter, Stephen B; O'Donoghue, Darragh; Romero-Colmenero, Encarni; O'Connor, James; Fourie, Piet; Evans, Geoff; Sass, Craig; Crause, Lisa; Still, Martin; Butters, O W; Norton, A J; Mukai, Koji


    We report optical spectroscopy and high speed photometry and polarimetry of the INTEGRAL source IGRJ14536-5522 (=Swift J1453.4-5524). The photometry, polarimetry and spectroscopy are modulated on an orbital period of 3.1564(1) hours. Orbital circularly polarized modulations are seen from 0 to -18 per cent, unambiguously identifying IGRJ14536-5522 as a polar. Some of the high speed photometric data show modulations that are consistent with quasi-periodic oscillations (QPOs) on the order of 5-6 minutes. Furthermore, for the first time, we detect the (5-6) minute QPOs in the circular polarimetry. We discuss the possible origins of these QPOs. We also include details of HIPPO, a new high-speed photo-polarimeter used for some of our observations.

  8. Unusual Sclerosing Orbital Pseudotumor Infiltrating Orbits and Maxillofacial Regions

    Directory of Open Access Journals (Sweden)

    Huseyin Toprak


    Full Text Available Idiopathic orbital pseudotumor (IOP is a benign inflammatory condition of the orbit without identifiable local or systemic causes. Bilateral massive orbital involvement and extraorbital extension of the IOP is very rare. We present an unusual case of IOP with bilateral massive orbital infiltration extending into maxillofacial regions and discuss its distinctive magnetic resonance imaging (MRI features that help to exclude other entities during differential diagnoses.

  9. Orbit correction algorithm for SSRF fast orbit feedback system

    Institute of Scientific and Technical Information of China (English)

    LIU Ming; YIN Chongxian; LIU Dekang


    A fast orbit feedback system is designed at SSRF to suppress beam orbit disturbance within sub-micron in the bandwidth up to 100 Hz.The SVD (Singular value decomposition) algorithm is applied to calculate the inverse response matrix in global orbit correction.The number of singular eigenvalues will influence orbit noise suppression and corrector strengths.The method to choose singular eigenvalue rejection threshold is studied in this paper,and the simulation and experiment results are also presented.

  10. Comparison of Low Earth Orbit and Geosynchronous Earth Orbits (United States)

    Drummond, J. E.


    The technological, environmental, social, and political ramifications of low Earth orbits as compared to geosynchronous Earth orbits for the solar power satellite (SPS) are assessed. The capital cost of the transmitting facilities is dependent on the areas of the antenna and rectenna relative to the requirement of high efficiency power transmission. The salient features of a low orbit Earth orbits are discussed in terms of cost reduction efforts.

  11. Device For Viewing Polarized Light (United States)

    Noever, David A.


    Technique for detection of polarized light based on observation of scene through two stacked polarizing disks. No need to rotate polarizers to create flicker indicative of polarization. Implemented by relatively simple, lightweight apparatus. Polarization seen as bow-tie rainbow pattern. Advantageous for detecting polarization in variety of meteorological, geological, astronomical, and related applications.

  12. Plasma Flowfields Around Low Earth Orbit Objects: Aerodynamics to Underpin Orbit Predictions (United States)

    Capon, Christopher; Boyce, Russell; Brown, Melrose


    Interactions between orbiting bodies and the charged space environment are complex. The large variation in passive body parameters e.g. size, geometry and materials, makes the plasma-body interaction in Low Earth Orbit (LEO) a region rich in fundamental physical phenomena. The aerodynamic interaction of LEO orbiting bodies with the neutral environment constitutes the largest non-conservative force on the body. However in general, study of the LEO plasma-body interaction has not been concerned with external flow physics, but rather with the effects on surface charging. The impact of ionospheric flow physics on the forces on space debris (and active objects) is not well understood. The work presented here investigates the contribution that plasma-body interactions have on the flow structure and hence on the total atmospheric force vector experienced by a polar orbiting LEO body. This work applies a hybrid Particle-in-Cell (PIC) - Direct Simulation Monte Carlo (DSMC) code, pdFoam, to self-consistently model the electrostatic flowfield about a cylinder with a uniform, fixed surface potential. Flow conditions are representative of the mean conditions experienced by the Earth Observing Satellite (EOS) based on the International Reference Ionosphere model (IRI-86). The electron distribution function is represented by a non-linear Boltzmann electron fluid and ion gas-surface interactions are assumed to be that of a neutralising, conducting, thermally accommodating solid wall with diffuse reflections. The variation in flowfield and aerodynamic properties with surface potential at a fixed flow condition is investigated, and insight into the relative contributions of charged and neutral species to the flow physics experienced by a LEO orbiting body is provided. This in turn is intended to help improve the fidelity of physics-based orbit predictions for space debris and other near-Earth space objects.

  13. Spin-sensitive atom mirror via spin-orbit interaction (United States)

    Zhou, Lu; Zheng, Ren-Fei; Zhang, Weiping


    Based on the spin-orbit coupling recently implemented in a neutral cold-atom gas, we propose a scheme to realize spin-dependent scattering of cold atoms. In particular we consider a matter wave packet of cold-atom gas impinging upon a step potential created by the optical light field, inside of which the atoms are subject to spin-orbit interaction. We show that the proposed system can act as a spin polarizer or spin-selective atom mirror for the incident atomic beam. The principle and the operating parameter regime of the system are carefully discussed.

  14. Spin-Orbit Splitting in Semiconductor Quantum Dots with a Two-Dimensional Ring Model

    Institute of Scientific and Technical Information of China (English)

    FENG Jun-Sheng; LIU Zheng


    We present a theoretical study of the energy levels with two-dimensional ring confining potential in the presence of the Rashba spin-orbit interaction.The features of some low-lying states in various strengths of the Rashba spin-orbit interaction are investigated.The Rashba spin-orbit splitting can also be influenced by the width of the potential barrier.The computed results show that the spin-polarized electronic states can be more easily achieved in a weakly confined dot when the confinement strength for the Rashba spin-orbit interaction is larger than a critical value.

  15. Earth scenes in polarized light observed from the Space Shuttle (United States)

    Whitehead, Victor S.; Coulson, Kinsell L.


    By means of a pair of boresighted and synchronized cameras fitted with orthogonally oriented polarizing filters and carried aboard the Space Shuttle, a large number of polarized images of the earth's surface have been obtained from orbital altitude. Selected pairs of images, both in color and in black and white, have been digitized and computer-processed to yield analogous images in each of the three Stokes parameters necessary for characterizing the state of linear polarization of the emergent light. Many of the images show surface properties more distinctly in degree and plane of polarization than in simple intensity alone. It is believed that these are the first, and certainly the most extensive, set of polarized images of the earth ever obtained from space. Selected pairs of the images are presented here along with some early results of analysis.

  16. Diffraction and polarization effects in Earth radiation budget measurements. (United States)

    Mahan, J R; Barki, A R; Priestley, K J


    Thermal radiation emitted and reflected from the Earth and viewed from near-Earth orbit may be characterized by its spectral distribution, its degree of coherence, and its state of polarization. The current generation of broadband Earth radiation budget instruments has been designed to minimize the effect of diffraction and polarization on science products. We used Monte Carlo ray-trace (MCRT) models that treat individual rays as quasi-monochromatic, polarized entities to explore the possibility of improving the performance of such instruments by including measures of diffraction and polarization during calibration and operation. We have demonstrated that diffraction and polarization sensitivity associated with typical Earth radiation budget instrument design features has a negligible effect on measurements.

  17. Diplopia secondary to orbital surgery. (United States)

    Silbert, David I; Matta, Noelle S; Singman, Eric L


    Diplopia may occur following any type of ocular or pericocular surgery. The surgeries most frequently associated with postoperative diplopia include: repair of orbital fracture, endoscopic sinus surgery (from inadvertent orbital penetration), and orbital decompression for thyroid-related immune orbitopathy (TRIO). Postoperative diplopia after orbital tumor resection has been reported--e.g., after excision of fibrous dysplasia and osteoma. However, a recent case series suggests diplopia after orbital tumor resection is uncommon and transient. Surgical intervention for orbital trauma carries the highest risk of postoperative diplopia and will be the focus of this review. We will also present a case report of worsening diplopia following repair of orbital floor fracture to highlight potential motility issues that can arise when implants are employed to treat orbital floor fractures.

  18. Topics in orbit equivalence

    CERN Document Server

    Kechris, Alexander S


    This volume provides a self-contained introduction to some topics in orbit equivalence theory, a branch of ergodic theory. The first two chapters focus on hyperfiniteness and amenability. Included here are proofs of Dye's theorem that probability measure-preserving, ergodic actions of the integers are orbit equivalent and of the theorem of Connes-Feldman-Weiss identifying amenability and hyperfiniteness for non-singular equivalence relations. The presentation here is often influenced by descriptive set theory, and Borel and generic analogs of various results are discussed. The final chapter is a detailed account of Gaboriau's recent results on the theory of costs for equivalence relations and groups and its applications to proving rigidity theorems for actions of free groups.

  19. Simple compactifications and polar decomposition of homogeneous real spherical spaces

    DEFF Research Database (Denmark)

    Knop, Friedrich; Krötz, Bernhard; Sayag, Eitan


    Let Z be an algebraic homogeneous space Z = G/H attached to real reductive Lie group G. We assume that Z is real spherical, i.e., minimal parabolic subgroups have open orbits on Z. For such spaces, we investigate their large scale geometry and provide a polar decomposition. This is obtained from...

  20. Light-induced spin polarizations in quantum rings

    NARCIS (Netherlands)

    Joibari, F.K.; Blanter, Y.M.; Bauer, G.E.W.


    Nonresonant circularly polarized electromagnetic radiation can exert torques on magnetizations by the inverse Faraday effect (IFE). Here, we discuss the enhancement of IFE by spin-orbit interactions. We illustrate the principle by studying a simple generic model system, i.e., the quasi-one-dimension

  1. Sciamachy in orbit: an overview of its objectives, the first year and some results (United States)

    Burrows, J.


    SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric ChartographY) was selected to be part of the ESA ENVISAT mission through an announcement of opportunity and its development is a national contribution to this mission, supported by Germany, The Netherlands and Belgium. ENVISAT was launched aboard the ESA ENVISAT at the end of February 2002. SCIAMACHY is a passive remote sensing instrument, which measures the extra terrestrial solar radiation and light scattered, reflected and emitted from the atmosphere at different viewing geometries. It has eight spectral channels, which observe contiguously from 220 to 1750 nm, as well as in the bands 1940-2040 nm and 2265-2380 nm. These measurements are made at channel dependent spectral resolutions between 0.2 and 1.4 nm. It also has seven polarisation monitoring devices, which measure the up-welling radiation at selected wavelengths and instrument defined planes of polarisation. The combination of the PMD and channel measurements enable the instrument polarisation characteristics to be accounted for and provides some information at higher spatial resolution, which is used for the interpretation of the cloud and aerosol in the field of view. The orbit of ENVISAT is sun synchronous, having an equator at 10.00 a.m. in a descending node. The measurement modes of SCIAMACHY comprise alternate limb and nadir measurements with solar and lunar occultation being, performed at the terminator in the northern and southern hemisphere respectively. The occultation and limb measurements extend from 0 to around 100 km, having vertical sampling at ~1.5 or ~3 km. The horizontal resolution of the limb and occultation measurements is approximately 240kmx400km and 30kmx400km respectively. The spatial resolution of the nadir measurements is between 30kmx30km and 30kmx240km dependent on the spectral region. The measurements of SCIAMACHY yield directly the extra terrestrial solar irradiance and the earth shine radiance. The targets

  2. Study on Radiation Condition in DAMPE Orbit by Analyzing the Engineering Data of BGO Calorimeter (United States)

    Feng, Changqing; Liu, Shubin; Zhang, Yunlong; Ma, Siyuan


    The DAMPE (DArk Matter Particle Explorer) is a scientific satellite which was successfully launched into a 500 Km sun-synchronous orbit, on December 17th, 2015, from the Jiuquan Satellite Launch Center of China. The major scientific objectives of the DAMPE mission are primary cosmic ray, gamma ray astronomy and dark matter particles, by observing high energy primary cosmic rays, especially positrons/electrons and gamma rays with an energy range from 5 GeV to 10 TeV. The BGO calorimeter is a critical sub-detector of DAMPE payload, for measuring the energy of cosmic particles, distinguishing positrons/electrons and gamma rays from hadron background, and providing trigger information. It utilizes 308 BGO (Bismuth Germanate Oxide) crystal logs with the size of 2.5cm*2.5cm*60cm for each log, to form a total absorption electromagnetic calorimeter. All the BGO logs are stacked in 14 layers, with each layer consisting of 22 BGO crystal logs and each log is viewed by two Hamamatsu R5610A PMTs (photomultiplier tubes), from both sides respectively. In order to achieve a large dynamic range, each PMT base incorporates a three dynode (2, 5, 8) pick off, which results in 616 PMTs and 1848 signal channels. The readout electronics system, which consists of 16 FEE (Front End Electronics) modules, was developed. Its main functions are based on the Flash-based FPGA (Field Programmable Gate Array) chip and low power, 32-channel VA160 and VATA160 ASICs (Application Specific Integrated Circuits) for precisely measuring the charge of PMT signals and providing "hit" signals as well. The hit signals are sent to the trigger module of PDPU (Payload Data Process Unit) and the hit rates of each layer is real-timely recorded by counters and packed into the engineering data, which directly reflect the flux of particles which fly into or pass through the detectors. In order to mitigate the SEU (Single Event Upset) effect in radioactive space environment, certain protecting methods, such as TMR

  3. Small Mercury Relativity Orbiter (United States)

    Bender, Peter L.; Vincent, Mark A.


    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.

  4. Martian clouds observed by Mars Global Surveyor Mars Orbiter Camera


    Wang, Huiqun; Ingersoll, Andrew P.


    We have made daily global maps that cover both polar and equatorial regions of Mars for Ls 135°–360° and 0°–111° using the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red and blue wide-angle swaths taken from May 1999 to January 2001. We study the seasonal distribution of condensate clouds and dust clouds during roughly 1 Martian year using these daily global maps. We present the development and decay of the tropical cloud belt and the polar hoods, the spatial and temporal distributi...

  5. Preseptal and orbital cellulitis

    Directory of Open Access Journals (Sweden)

    Emine Akçay


    Full Text Available 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. epidermidis, Haempphilus influenzae, Moraxella catarrhalis and S. pyogenes. The method for the diagnosis of OS and PS is computed tomography. Using effective antibiotics is a mainstay for the treatment of PC and OC. There is an agreement that surgical drainage should be performed in cases of complete ophthalmoplegia or significant visual impairment or large abscesses formation. This infections are also at a greater risk of acute visual loss, cavernous sinus thrombosis, meningitis, cerebritis, endophthalmitis, and brain abscess in children. Early diagnosis and appropriate treatment are crucial to control the infection. Diagnosis, treatment, management and complications of PC and OC are summarized in this manuscript. J MicrobiolInfect Dis 2014; 4(3: 123-127

  6. The Changing Polar Moon (United States)

    Lucey, P. G.; Hurley, D.


    The Lunar Reconnaissance Orbiter (LRO) and LCROSS have provided an avalanche of new data regarding the lunar poles: LCROSS directly detected water vapor and other volatiles in its impact plume; LRO LAMP has detected surface frost using UV ratios; LEND has refined understanding of the distribution of hydrogen; LOLA and LAMP have showed that the spectral properties of permanently shadowed regions (PSR) are anomalous and may be due to unusual surface texture or altered space weathering; Diviner shows both where the coldest portions of the poles exist, and its quantitative results show where temperatures are low enough to preserve water ice at depth, well outside the PSRs. Yet while we are data rich, our understanding of the lunar poles is maddeningly poor. Our poverty of understanding is made even more baffling by the MESSENGER results from Mercury. At Mercury's poles the distribution of volatiles is dictated by temperature: where subsurface temperatures inferred from topography are consistent with long term preservation of water ice, radar anomalies indicating thick ice are present; where surface temperatures are consistent with preservation of surface frost, high reflectance anomalies indicating surface frost are revealed by laser reflectance. The distribution of water ice on Mercury is well understood. In contrast, temperature is only a weak indicator of the presence of volatiles at the lunar poles; there is little ability to predict the location and abundance of hydrogen or water. The difference may in the age of the volatile deposits on the two planets. Turn the clock forward a few billion years on Mercury and the deposits may appear more lunar. Surface lag deposits may have long ago succumbed to impact gardening, as has much of the shallow buried ice. Ice retained could be patchy, and confined to the coldest places that may tend to preserve it more effectively, even when finely comminuted. Lunar polar volatiles, a possible relic of an ancient, Mercury

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

    DEFF Research Database (Denmark)

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


    [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...

  8. Synthesizing radar maps of polar regions with a Doppler-only method. (United States)

    Roulston, M S; Muhleman, D O


    A method for producing a radar-reflectivity map of the polar regions of the Moon or a planet from polar orbit with only the frequency shift of the reflected signals is described and simulated. A Radon transform of the reflectivity is obtained during multiple passes over the pole. Inversion of this Radon transform enables a map of radar reflectivity to be synthesized.

  9. Chaos Behaviour of Molecular Orbit

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-Tang; SUN Fu-Yan; SHEN Shu-Lan


    Based on H(u)ckel's molecular orbit theory,the chaos and;bifurcation behaviour of a molecular orbit modelled by a nonlinear dynamic system is studied.The relationship between molecular orbit and its energy level in the nonlinear dynamic system is obtained.

  10. Orbiter OMS and RCS technology (United States)

    Boudreaux, R. A.


    Orbiter Orbital Maneuver Subsystem (OMS) and Reaction Control Subsystem (RCS) tankage has proved to be highly successful in shuttle flights on-orbit propellant transfer tests were done. Tank qualification tests along with flight demonstrations were carried out future uses of storable propellants are cited.

  11. Interaction between subdaily Earth rotation parameters and GPS orbits (United States)

    Panafidina, Natalia; Seitz, Manuela; Hugentobler, Urs


    In processing GPS observations the geodetic parameters like station coordinates and ERPs (Earth rotation parameters) are estimated w.r.t. the celestial reference system realized by the satellite orbits. The interactions/correlations between estimated GPS orbis and other parameters may lead to numerical problems with the solution and introduce systematic errors in the computed values: the well known correlations comprise 1) the correlation between the orbital parameters determining the orientation of the orbital plane in inertial space and the nutation and 2) in the case of estimating ERPs with subdaily resolution the correlation between retrograde diurnal polar motion and nutation (and so the respective orbital elements). In this contribution we study the interaction between the GPS orbits and subdaily model for the ERPs. Existing subdaily ERP model recommended by the IERS comprises ~100 terms in polar motion and ~70 terms in Universal Time at diurnal and semidiurnal tidal periods. We use a long time series of daily normal equation systems (NEQ) obtaine from GPS observations from 1994 till 2007 where the ERPs with 1-hour resolution are transformed into tidal terms and the influence of the tidal terms with different frequencies on the estimated orbital parameters is considered. We found that although there is no algebraic correlation in the NEQ between the individual orbital parameters and the tidal terms, the changes in the amplitudes of tidal terms with periods close to 24 hours can be better accmodated by systematic changes in the orbital parameters than for tidal terms with other periods. Since the variation in Earth rotation with the period of siderial day (23.93h, tide K1) in terrestrial frame has in inertial space the same period as the period of revolution of GPS satellites, the K1 tidal term in polar motion is seen by the satellites as a permanent shift. The tidal terms with close periods (from ~24.13h to ~23.80h) are seen as a slow rotation of the

  12. Polar varieties revisited


    Piene, Ragni


    We recall the definition of classical polar varieties, as well as those of affine and projective reciprocal polar varieties. The latter are defined with respect to a non-degenerate quadric, which gives us a notion of orthogonality. In particular we relate the reciprocal polar varieties to the "Euclidean geometry" in projective space. The Euclidean distance degree and the degree of the focal loci can be expressed in terms of the ranks, i.e., the degrees of the classical polar varieties, and he...

  13. Polarization at SLC

    Energy Technology Data Exchange (ETDEWEB)

    Swartz, M.L.


    The SLAC Linear Collider has been designed to readily accommodate polarized electron beams. Considerable effort has been made to implement a polarized source, a spin rotation system, and a system to monitor the beam polarization. Nearly all major components have been fabricated. At the current time, several source and polarimeter components have been installed. The installation and commissioning of the entire system will take place during available machine shutdown periods as the commissioning of SLC progresses. It is expected that a beam polarization of 45% will be achieved with no loss in luminosity. 13 refs., 15 figs.

  14. Polarized negative ions

    Energy Technology Data Exchange (ETDEWEB)

    Haeberli, W.


    This paper presents a survey of methods, commonly in use or under development, to produce beams of polarized negative ions for injection into accelerators. A short summary recalls how the hyperfine interaction is used to obtain nuclear polarization in beams of atoms. Atomic-beam sources for light ions are discussed. If the best presently known techniques are incorporated in all stages of the source, polarized H/sup -/ and D/sup -/ beams in excess of 10 can probably be achieved. Production of polarized ions from fast (keV) beams of polarized atoms is treated separately for atoms in the H(25) excited state (Lamb-Shift source) and atoms in the H(1S) ground state. The negative ion beam from Lamb-Shift sources has reached a plateau just above 1, but this beam current is adequate for many applications and the somewhat lower beam current is compensated by other desirable characteristics. Sources using fast polarized ground state atoms are in a stage of intense development. The next sections summarize production of polarized heavy ions by the atomic beam method, which is well established, and by optical pumping, which has recently been demonstrated to yield very large nuclear polarization. A short discussion of proposed ion sources for polarized /sup 3/He/sup -/ ions is followed by some concluding remarks.

  15. Telemachus: a mission for a polar view of solar activity (United States)

    Roelof, E. C.; Andrews, G. B.; Liewer, P. C.; Moses, D.


    Telemachus is a polar solar-heliospheric mission described in the current NASA Sun-Earth Connections Roadmap (2003-2028). To continue the quest begun by Ulysses, Telemachus will be injected into a 0.2 AU × 2.5 AU solar polar orbit after gravitational encounters with Venus, Earth (twice) and Jupiter, followed by a maneuver at first perihelion. With an orbital period of 1.5 years, it will pass over the solar poles at a radial distance of 0.37 AU. The behavior of solar polar flows (heretofore unobservable) will provide critical boundary conditions on the transport of solar magnetic fields. Manifestations of the global flows and fields are the solar dynamo, formation of active regions, emission of the solar wind and the heliospheric magnetic field, launching of coronal mass ejections, eruption of solar flares, acceleration of solar energetic particles, and ultimately the dynamics of the entire heliosphere.

  16. Laser induced electron diffraction: a tool for molecular orbital imaging

    CERN Document Server

    Peters, Michel; Charron, Eric; Keller, Arne; Atabek, Osman


    We explore the laser-induced ionization dynamics of N2 and CO2 molecules subjected to a few-cycle, linearly polarized, 800\\,nm laser pulse using effective two-dimensional single active electron time-dependent quantum simulations. We show that the electron recollision process taking place after an initial tunnel ionization stage results in quantum interference patterns in the energy resolved photo-electron signals. If the molecule is initially aligned perpendicular to the field polarization, the position and relative heights of the associated fringes can be related to the molecular geometrical and orbital structure, using a simple inversion algorithm which takes into account the symmetry of the initial molecular orbital from which the ionized electron is produced. We show that it is possible to extract inter-atomic distances in the molecule from an averaged photon-electron signal with an accuracy of a few percents.

  17. Optical Nanoprobing via Spin-Orbit Interaction of Light (United States)

    Rodríguez-Herrera, Oscar G.; Lara, David; Bliokh, Konstantin Y.; Ostrovskaya, Elena A.; Dainty, Chris


    We show, both theoretically and experimentally, that high-numerical-aperture (NA) optical microscopy is accompanied by strong spin-orbit interaction of light, which translates fine information about the specimen to the polarization degrees of freedom of light. An 80 nm gold nanoparticle scattering the light in the focus of a high-NA objective generates angular momentum conversion, which is seen as a nonuniform polarization distribution at the exit pupil. We demonstrate remarkable sensitivity of the effect to the position of the nanoparticle: Its subwavelength displacement produces the giant spin-Hall effect, i.e., macroseparation of spins in the outgoing light. This brings forth a far-field optical nanoprobing technique based on the spin-orbit interaction of light.

  18. Improving Tidal Measurements about Europa Using the Properties of Unstable Periodic Orbits (United States)

    Boone, Dylan; Scheeres, D. J.


    The NASA Jupiter Europa Orbiter mission requires a circular, near-polar orbit to measure Europa's Love numbers, geophysical coefficients which give insight into whether a liquid ocean exists. This type of orbit about planetary satellites is known to be unstable. The effects of Jupiter's tidal gravity are seen in changes in Europa's gravity field and surface deformation, which are sensed through doppler tracking over time and altimetry measurements respectively. These two measurement types separately determine the h and k Love numbers, a combination of which bounds how thick the ice shell of Europa is and whether liquid water is present. This work shows how the properties of an unstable periodic orbit about Europa generate preferred measurement directions in the orbit determination process for estimating science parameters. We generate an error covariance over seven days for the orbiter state and science parameters and then disperse the orbit initial conditions in a Monte Carlo simulation according to this covariance. The dispersed orbits are shown to have a bias toward longer lifetimes and we discuss this as an effect of the stable and unstable manifolds of the periodic orbit. The stable manifold represents contraction forward in time and the unstable manifold represents expansion forward in time. However, using an epoch formulation of a square-root information filter, measurements aligned with the unstable manifold mapped back in time add more information to the orbit determination process than measurements aligned with the stable manifold. This corresponds to a contraction in the uncertainty of the estimate of the desired parameters, including the Love numbers. Low altitude, near-polar periodic orbits with these characteristics are discussed along with the estimation results for the Love numbers, orbiter state, and orbit lifetime. These results are applicable to other measurements and planetary satellites since the mathematical model is the same.

  19. Valley polarization in magnetically doped single-layer transition-metal dichalcogenides

    KAUST Repository

    Cheng, Yingchun


    We demonstrate that valley polarization can be induced and controlled in semiconducting single-layer transition-metal dichalcogenides by magnetic doping, which is important for spintronics, valleytronics, and photonics devices. As an example, we investigate Mn-doped MoS2 by first-principles calculations. We study how the valley polarization depends on the strength of the spin orbit coupling and the exchange interaction and discuss how it can be controlled by magnetic doping. Valley polarization by magnetic doping is also expected for other honeycomb materials with strong spin orbit coupling and the absence of inversion symmetry.

  20. Orbit Propagation and Determination of Low Earth Orbit Satellites

    Directory of Open Access Journals (Sweden)

    Ho-Nien Shou


    Full Text Available This paper represents orbit propagation and determination of low Earth orbit (LEO satellites. Satellite global positioning system (GPS configured receiver provides position and velocity measures by navigating filter to get the coordinates of the orbit propagation (OP. The main contradictions in real-time orbit which is determined by the problem are orbit positioning accuracy and the amount of calculating two indicators. This paper is dedicated to solving the problem of tradeoffs. To plan to use a nonlinear filtering method for immediate orbit tasks requires more precise satellite orbit state parameters in a short time. Although the traditional extended Kalman filter (EKF method is widely used, its linear approximation of the drawbacks in dealing with nonlinear problems was especially evident, without compromising Kalman filter (unscented Kalman Filter, UKF. As a new nonlinear estimation method, it is measured at the estimated measurements on more and more applications. This paper will be the first study on UKF microsatellites in LEO orbit in real time, trying to explore the real-time precision orbit determination techniques. Through the preliminary simulation results, they show that, based on orbit mission requirements and conditions using UKF, they can satisfy the positioning accuracy and compute two indicators.

  1. Galactic Habitable Orbits (United States)

    Rahimi, A.; Mao, S.; Kawata, D.


    The fossil record shows that the Earth has experienced several mass extinctions over the past 500 million years1, and it has been suggested that there is a periodicity in extinction events on timescales of tens1 and/or hundreds of millions of years. Various hypotheses have been proposed to explain the cause of the mass extinctions, including the suggestion that the Earth's ozone layer may have been destroyed by intense radiation from a nearby supernovae2- 3, exposing the Earth's surface to damaging UV radiation. Recent observations of cores taken from the ocean floor revealed atoms of a very rare isotope of iron (60Fe) believed to have arrived on Earth around 2 million years ago as fallout from a nearby supernovae4. Astronomical evidence for that past supernovae was recently found in the debris of a young cluster of massive stars5, by tracing its past orbit, putting it at the right place at the right time to explain the mild extinction event. Here we report new high-resolution (both in space and time) N-body chemodynamical simulations (carried out with our novel code GCD+6) of the evolution of a model Milky Way Galaxy, tracing the orbit of èsun-like' stars over a 500 million year period, checking the proximity to supernovae throughout the history of the orbit and comparing the times when this occurs with past mass extinctions on Earth. We additionally explain the important effects of the spiral arm pattern, radial migration of stars and Galactic chemistry on habitability.

  2. Fourier Series Approximations to J2-Bounded Equatorial Orbits

    Directory of Open Access Journals (Sweden)

    Wei Wang


    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.

  3. On-Orbit Noise Characterization of MODIS Reflective Solar Bands (United States)

    Angal, Amit; Xiong, Xiaoxiong; Sun, Junqiang; Geng, Xu


    The Moderate Resolution Imaging Spectroradiometer (MODIS), launched on the Terra and Aqua spacecrafts, was designed to collect complementary and comprehensive measurements of the Earth's properties on a global scale. The 20 reflective solar bands (RSBs), covering a wavelength range from 0.41 to 2.1 micrometers, are calibrated on-orbit using regularly scheduled solar diffuser (SD) observations. Although primarily used for on-orbit gain derivation, the SD observations also facilitate the characterization of the detector signal-to-noise ratio (SNR). In addition to the calibration requirement of 2% for the reflectance factors and 5% for the radiances, the required SNRs are also specified for all RSB at their typical scene radiances. A methodology to characterize the on-orbit SNR for the MODIS RSB is presented. Overall performance shows that a majority of the RSB continue to meet the specification, therefore performing well. A temporal decrease in the SNR, observed in the short-wavelength bands, is attributed primarily to the decrease in their detector responses. With the exception of the inoperable and noisy detectors in band 6 identified prelaunch, the detectors of AquaMODIS RSB perform better than TerraMODIS. The approach formulated for on-orbit SNR characterization can also be used by other sensors that use on-board SDs for their on-orbit calibration (e.g., Suomi National Polar-Orbiting Partnership [SNPP]-Visible Infrared Imaging Radiometer Suite).

  4. Review of orbital imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goh, P.S. [Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074 (Singapore)], E-mail:; Gi, M.T. [Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074 (Singapore); Charlton, A. [Department of Pathology, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074 (Singapore); Tan, C.; Gangadhara Sundar, J.K.; Amrith, S. [Department of Ophthalmology, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074 (Singapore)


    CT and MRI are commonly used in the evaluation of patients with suspected orbital disease. Many different diseases may present within this small anatomical space. The purpose of this article is to present a diagnostic strategy based on a compartment model. Localizing pathology to sinus, bone, extraconal space, muscle cone, intraconal space, optic nerve, globe or lacrimal fossa allows significant reduction in the number of differential diagnoses as these compartments contain different tissues which disease may involve or arise from. Certain diseases may also present in multiple compartments. Common diseases which might present in one or multiple compartments will be discussed.

  5. Lunar Exploration Orbiter (LEO) (United States)

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


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

  6. Plasma polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Iwamae, Atsushi; Inoue, Takeru; Tanaka, Akihiro; Kawakami, Kazuki; Fujimoto, Takashi [Kyoto Univ., Dept. of Engineering Physics, Kyoto (Japan)


    Polarization of radiation emitted from plasma reflects the anisotropic properties of the plasma, especially the angular isotropic distribution of electron velocities. Polarization has been observed on impurity ion lines from the WT-3 tokamak and GAMMA 10 tandem mirror device. (author)

  7. Planetary polarization nephelometer

    NARCIS (Netherlands)

    Banfield, D.; Dissly, R.; Mishchenko, M.; Muñoz, O.; Roos-Serote, M.; Stam, D.M.; Volten, H.; Wilson, A.


    We have proposed to develop a polarization nephelometer for use on future planetary descent probes. It will measure both the scattered intensity and polarization phase functions of the aerosols it encounters descending through an atmosphere. These measurements will be taken at two wavelengths

  8. Polar Cap Patch Dynamics (United States)


    cap arcs Citation: Hosokawa, K., J. I. Moen, K. Shiokawa, and Y. Otsuka ( 2011 ), Motion of polar cap arcs , J. Geophys. Res. , 116 , A01305, doi...K., J. I. Moen, K. Shiokawa, and Y. Otsuka , (2011), Decay of polar cap patch, J. Geophys. Res., 116, A05308, doi:10.1029/2010JA016287, Abstract. We

  9. Polar Code Validation (United States)


    SUMMARY OF POLAR ACHIEVEMENTS ..... .......... 3 3. POLAR CODE PHYSICAL MODELS ..... ............. 5 3.1 PL- ASMA Su ^"ru5 I1LS SH A...of this problem. 1.1. The Charge-2 Rocket The Charge-2 payload was launched on a Black Brant VB from White Sands Mis- sile Range in New Mexico in

  10. Polarization modulators for CMBPol

    Energy Technology Data Exchange (ETDEWEB)

    Ade, P A R; Savini, G [Cardiff University, School of Physics and Astronomy, Queens Buildings, The Parade, Cardiff, CF24 3AA (United Kingdom); Chuss, D T [NASA Goddard Space Flight Center, Code 665, Greenbelt, MD, 20771 (United States); Hanany, S [School of Physics and Astronomy, University of Minnesota/Twin Cities, Minneapolis, MN, 55455 (United States); Haynes, V; Pisano, G [University of Manchester, School of Physics and Astronomy - Alan Turing Building, Upper Brooke street, Manchester, M13 4PL (United Kingdom); Keating, B G [Department of Physics, University of California, San Diego, La Jolla, CA 92093-0424 (United States); Kogut, A [Code 665 Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ruhl, J E [Physics Department, Case Western Reserve University, Cleveland, OH, 44106 (United States); Wollack, E J [Observational Cosmology Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)


    We review a number of technologies that are candidates for active polarization modulators for CMBPol. The technologies are appropriate for instruments that use bolometric detectors and include birefringent crystal-based and metal-mesh-based half-wave plates, variable phase polarization modulator, Faraday rotator, and photolithographed modulators. We also give a current account of the status of millimeter-wave orthomode transducers.

  11. Polarized Light: Three Demonstrations. (United States)

    Goehmann, Ruth; Welty, Scott


    Describes three demonstrations used in the Chicago Museum of Science and Industry polarized light show. The procedures employed are suitable for the classroom by using smaller polarizers and an overhead projector. Topic areas include properties of cellophane tape, nondisappearing arrows, and rope through a picket fence. (JN)

  12. Planetary polarization nephelometer

    NARCIS (Netherlands)

    Banfield, D.; Dissly, R.; Mishchenko, M.; Muñoz, O.; Roos-Serote, M.; Stam, D.M.; Volten, H.; Wilson, A.


    We have proposed to develop a polarization nephelometer for use on future planetary descent probes. It will measure both the scattered intensity and polarization phase functions of the aerosols it encounters descending through an atmosphere. These measurements will be taken at two wavelengths separa

  13. Our Polar Past (United States)

    Clary, Renee; Wandersee, James


    The study of polar exploration is fascinating and offers students insights into the history, culture, and politics that affect the developing sciences at the farthest ends of Earth. Therefore, the authors think there is value in incorporating polar exploration accounts within modern science classrooms, and so they conducted research to test their…

  14. Polarized Light: Three Demonstrations. (United States)

    Goehmann, Ruth; Welty, Scott


    Describes three demonstrations used in the Chicago Museum of Science and Industry polarized light show. The procedures employed are suitable for the classroom by using smaller polarizers and an overhead projector. Topic areas include properties of cellophane tape, nondisappearing arrows, and rope through a picket fence. (JN)

  15. Nomenclature of polarized light - Elliptical polarization (United States)

    Clarke, D.


    Alternative handedness and sign conventions for relating the orientation of elliptical polarization are discussed. The discussion proceeds under two headings: (1) snapshot picture, where the emphasis for the convention is contained in the concept of handedness; and (2) angular momentum consideration, where the emphasis for the convention is strongly associated with mathematical convention and the sign of the fourth Stokes parameter.

  16. A comprehensive mission to planet Earth: Woods Hole Space Science and Applications Advisory Committee Planning Workshop (United States)


    The NASA program Mission to Planet Earth (MTPE) is described in this set of visuals presented in Massachusetts on July 29, 1991. The problem presented in this document is that the earth system is changing and that human activity accelerates the rate of change resulting in increased greenhouse gases, decreasing levels of stratospheric ozone, acid rain, deforestation, decreasing biodiversity, and overpopulation. Various national and international organizations are coordinating global change research. The complementary space observations for this activity are sun-synchronous polar orbits, low-inclination, low altitude orbits, geostationary orbits, and ground measurements. The Geostationary Earth Observatory is the major proposed mission of MTPE. Other proposed missions are EOS Synthetic Aperture Radar, ARISTOTELES Magnetic Field Experiment, and the Global Topography Mission. Use of the NASA DC-8 aircraft is outlined as carrying out the Airborne Science and Applications Program. Approved Earth Probes Program include the Total Ozone Mapping Spectrometer (TOMS). Other packages for earth observation are described.

  17. Unique Offerings of the ISS as an Earth Observing Platform (United States)

    Cooley, Victor M.


    The International Space Station offers unique capabilities for earth remote sensing. An established Earth orbiting platform with abundant power, data and commanding infrastructure, the ISS has been in operation for twelve years as a crew occupied science laboratory and offers low cost and expedited concept-to-operation paths for new sensing technologies. Plug in modularity on external platforms equipped with structural, power and data interfaces standardizes and streamlines integration and minimizes risk and start up difficulties. Data dissemination is also standardized. Emerging sensor technologies and instruments tailored for sensing of regional dynamics may not be worthy of dedicated platforms and launch vehicles, but may well be worthy of ISS deployment, hitching a ride on one of a variety of government or commercial visiting vehicles. As global acceptance of the urgent need for understanding Climate Change continues to grow, the value of ISS, orbiting in Low Earth Orbit, in complementing airborne, sun synchronous polar, geosynchronous and other platform remote sensing will also grow.

  18. Parallel Polarization State Generation (United States)

    She, Alan; Capasso, Federico


    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristics with applications in spectroscopic ellipsometry, spectropolarimetry, communications, imaging, and security.

  19. Parallel Polarization State Generation

    CERN Document Server

    She, Alan


    The control of polarization, an essential property of light, is of wide scientific and technological interest. The general problem of generating arbitrary time-varying states of polarization (SOP) has always been mathematically formulated by a series of linear transformations, i.e. a product of matrices, imposing a serial architecture. Here we show a parallel architecture described by a sum of matrices. The theory is experimentally demonstrated by modulating spatially-separated polarization components of a laser using a digital micromirror device that are subsequently beam combined. This method greatly expands the parameter space for engineering devices that control polarization. Consequently, performance characteristics, such as speed, stability, and spectral range, are entirely dictated by the technologies of optical intensity modulation, including absorption, reflection, emission, and scattering. This opens up important prospects for polarization state generation (PSG) with unique performance characteristi...

  20. Spin motion at and near orbital resonance in storage rings with Siberian snakes I. At orbital resonance

    Energy Technology Data Exchange (ETDEWEB)

    Barber, D.P.; Vogt, M.


    Here, and in a sequel, we invoke the invariant spin field to provide an in-depth study of spin motion at and near low order orbital resonances in a simple model for the effects of vertical betatron motion in a storage ring with Siberian Snakes. This leads to a clear understanding, within the model, of the behaviour of the beam polarization at and near so-called snake resonances in proton storage rings. (orig.)

  1. High Power Microwave Emission of Large and Small Orbit Gyrotron Devices in Rectangular Interaction Structures (United States)

    Hochman, J. M.; Gilgenbach, R. M.; Jaynes, R. L.; Rintamaki, J. I.; Luginsland, J. W.; Lau, Y. Y.; Spencer, T. A.


    Experiments utilize large and small orbit e-beam gyrotron devices in a rectangular-cross-section (RCS) gyrotron. This device is being explored to examine polarization control. Other research issues include pulse shortening, and mode competition. MELBA generates electron beams with parameters of: -800kV, 1-10kA diode current, and 0.5-1.0 μ sec pulselengths. The small orbit gyrotron device is converted to a large orbit experiment by running MELBA's annular electron beam through a magnetic cusp. Initial experiments showed an increase in beam alpha (V_perp/V_par) of a factor of ~ 4 between small and large orbit devices. Experimental results from the RCS gyrotron will be compared for large-orbit and small-orbit electron beams. Beam transport data and frequency measurements will be presented. Computer modeling utilizing the MAGIC and E-gun codes will be shown.

  2. Optimized traverse planning for future polar prospectors based on lunar topography (United States)

    Speyerer, E. J.; Lawrence, S. J.; Stopar, J. D.; Gläser, P.; Robinson, M. S.; Jolliff, B. L.


    To fully understand the extensive collection of remotely sensed polar observations by the Lunar Reconnaissance Orbiter and other recent lunar missions, we must acquire an array of ground-truth measurements. A polar rover can sample and assay potential polar resources both laterally and at shallow depths. To identify ideal, least-energy traverses for such a polar prospecting mission, we developed a traverse planning tool, called R-Traverse, using a fundamental wheel-regolith interaction model and datasets from the Lunar Reconnaissance Orbiter Camera, Lunar Orbiter Laser Altimeter, and Diviner Lunar Radiometer Experiment. Using the terramechanics model, we identified least-energy traverses at the 20 m scale around Shackleton crater and located one traverse plan that enables the rover to remain illuminated for 94.4% of the lunar year. By incorporating this path planning tool during mission planning, the feasibility of such a mission can be quantified.

  3. Periodic orbits for three and four co-orbital bodies (United States)

    Verrier, P. E.; McInnes, C. R.


    We investigate the natural families of periodic orbits associated with the equilibrium configurations of the planar-restricted 1 + n-body problem for the case 2 ≤ n ≤ 4 equal-mass satellites. Such periodic orbits can be used to model both trojan exoplanetary systems and parking orbits for captured asteroids within the Solar system. For n = 2, there are two families of periodic orbits associated with the equilibria of the system: the well-known horseshoe and tadpole orbits. For n = 3, there are three families that emanate from the equilibrium configurations of the satellites, while for n = 4, there are six such families as well as numerous additional connecting families. The families of periodic orbits are all of the horseshoe or tadpole type, and several have regions of neutral linear stability.

  4. Periodic orbits for 3 and 4 co-orbital bodies

    CERN Document Server

    Verrier, Patricia


    We investigate the natural families of periodic orbits associated with the equilibrium configurations of the the planar restricted $1+n$ body problem for the case $2\\leq n \\leq 4$ equal mass satellites. Such periodic orbits can be used to model both trojan exoplanetary systems and parking orbits for captured asteroids within the solar system. For $n=2$ there are two families of periodic orbits associated with the equilibria of the system: the well known horseshoe and tadpole orbits. For $n=3$ there are three families that emanate from the equilibrium configurations of the satellites, while for $n=4$ there are six such families as well as numerous additional connecting families. The families of periodic orbits are all of the horseshoe or tadpole type, and several have regions of neutral linear stability.

  5. Orbital debris issues (United States)

    Kessler, D. J.

    Orbital debris issues fall into three major topics: Environment Definition, Spacecraft Hazard, and Space Object Management. The major issue under Environment Definition is defining the debris flux for sizes smaller (10 cm in diameter) than those tracked by the North American Aerospace Defense Command (NORAD). Sources for this size debris are fragmentation of larger objects, either by explosion or collision, and solid rocket motor products. Modeling of these sources can predict fluxes in low Earth orbit which are greater than the meteoroid environment. Techniques to measure the environment in the size interval between 1 mm and 10 cm are being developed, including the use of telescopes and radar both on the ground and in space. Some impact sensors designed to detect meteoroids may have detected solid rocket motor products. Once the environment is defined, it can be combined with hypervelocity impact data and damage criteria to evaluate the Spacecraft Hazard. Shielding may be required to obtain an acceptable damage level. Space Object Management includes techniques to control the environment and the desired policy to effectively minimize the hazard to spacecraft. One control technique - reducing the likelihood of future explosions in space - has already been implemented by NASA. The effectiveness of other techniques has yet to be evaluated.

  6. [Endoscopic approaches to the orbit]. (United States)

    Cebula, H; Lahlou, A; De Battista, J C; Debry, C; Froelich, S


    During the last decade, the use of endoscopic endonasal approaches to the pituitary has increased considerably. The endoscopic endonasal and transantral approaches offer a minimally invasive alternative to the classic transcranial or transconjunctival approaches to the medial aspect of the orbit. The medial wall of the orbit, the orbital apex, and the optic canal can be exposed through a middle meatal antrostomy, an anterior and posterior ethmoidectomy, and a sphenoidotomy. The inferomedial wall of the orbit can be also perfectly visualized through a sublabial antrostomy or an inferior meatal antrostomy. Several reports have described the use of an endoscopic approach for the resection or the biopsy of lesions located on the medial extraconal aspect of the orbit and orbital apex. However, the resection of intraconal lesions is still limited by inadequate instrumentation. Other indications for the endoscopic approach to the orbit are the decompression of the orbit for Graves' ophthalmopathy and traumatic optic neuropathy. However, the optimal management of traumatic optic neuropathy remains very controversial. Endoscopic endonasal decompression of the optic nerve in case of tumor compression could be a more valid indication in combination with radiation therapy. Finally, the endoscopic transantral treatment of blowout fracture of the floor of the orbit is an interesting option that avoids the eyelid or conjunctive incision of traditional approaches. The collaboration between the neurosurgeon and the ENT surgeon is mandatory and reduces the morbidity of the approach. Progress in instrumentation and optical devices will certainly make this approach promising for intraconal tumor of the orbit.

  7. Polarization Ratio Determination with Two Identical Linearly Polarized Antennas (United States)


    Polarization Ratio Determination with Two Identical Linearly Polarized Antennas Herbert M. Aumann1, Francis G. Willwerth2 and Kristan A. Abstract— This paper describes a method for determining the complex polarization ratio using two identical, linearly polarized antennas. By...present paper it will be shown that the later technique can also be used to determine the polarization ratio of a linearly polarized antenna. II

  8. The polarized electron beam at ELSA (United States)

    Hoffmann, M.; Drachenfels, W. V.; Frommberger, F.; Gowin, M.; Helbing, K.; Hillert, W.; Husmann, D.; Keil, J.; Michel, T.; Naumann, J.; Speckner, T.; Zeitler, G.


    The future medium energy physics program at the electron stretcher accelerator ELSA of Bonn University mainly relies on experiments using polarized electrons in the energy range from 1 to 3.2 GeV. To provide a polarized beam with high polarization and sufficient intensity a dedicated source has been developed and set into operation. To prevent depolarization during acceleration in the circular accelerators several depolarizing resonances have to be corrected for. Intrinsic resonances are compensated using two pulsed betatron tune jump quadrupoles. The influence of imperfection resonances is successfully reduced applying a dynamic closed orbit correction in combination with an empirical harmonic correction on the energy ramp. In order to minimize beam depolarization, both types of resonances and the correction techniques have been studied in detail. It turned out that the polarization in ELSA can be conserved up to 2.5 GeV and partially up to 3.2 GeV which is demonstrated by measurements using a Møller polarimeter installed in the external GDH1-beamline. .

  9. Polar constellations design for discontinuous coverage (United States)

    Sarno, Salvatore; Graziano, Maria Daniela; D'Errico, Marco


    A novel constellation design method is developed for discontinuous coverage of the globe and polar caps. It integrates and extends the applicability of the coverage regions and mitigates the limitations of the existing techniques based on streets-of-coverage (SOC) theory. In particular, the visibility conditions of the targets are mapped in the (Ω, u)-domain to identify the number of satellites per plane and the distance between successive orbits, whereas the planes are arranged around the equator exploiting satellites both in ascending and descending phase. The proposed approach is applied to design potential space segments in polar LEO supporting the existing maritime surveillance services over the globe and on the future polar routes. Results show they require a smaller total number of satellites with respect to the SOC-based configurations for revisit times less than one hour and wide range of swaths. In details, it is observed a reduction between 6% and 22% for global coverage and between 24% and 33% for the coverage of polar caps.

  10. A Typical Presentation of Orbital Pseudotumor Mimicking Orbital Cellulitis

    Directory of Open Access Journals (Sweden)

    J. Ayatollahi


    Full Text Available Introduction: Orbital pseudotumor, also known as idiopathic orbital inflammatory syndrome (IOIS, is a benign, non- infective inflammatory condition of the orbit without identifiable local or systemic causes. The disease may mimics a variety of pathologic conditions. We pre-sent a case of pseudotumor observed in a patient admitted under the name of orbital celluli-ties. Case Report: A 26-year-old woman reffered to our hospital with the history of left ocular pain and headache 2 days before her visit.. Ophthalmological examination of the patient was normal except for the redness and lid edema, mild chemosis and conjunctival injection. Gen-eral assessment was normal but a low grade fever was observed. She was hospitalized as an orbital cellulitis patient. She was treated with intravenous antibiotics. On the third day , sud-denly diplopia, proptosis in her left eye and ocular pain in her right side appeared. MRI re-vealed bilateral enlargement of extraocular muscles. Diagnosis of orbital pseudotumor was made and the patient was treated with oral steroid.She responded promptly to the treatment. Antibiotics were discontinued and steroid was tapered in one month period under close fol-low up. Conclusion: The clinical features of orbital pseudotumor vary widely . Orbital pseudotumor and orbital cellulitis can occasionally demonstrate overlapping features.. Despite complete physical examination and appropriate imaging, sometimes correct diagnosis of the disease would be difficult (Sci J Hamadan Univ Med Sci 2013; 20 (3:256-259

  11. Arbitrary orbital angular momentum of photons

    CERN Document Server

    Pan, Yue; Ren, Zhi-Cheng; Wang, Xi-Lin; Tu, Chenghou; Li, Yongnan; Wang, Hui-Tian


    Orbital angular momentum (OAM) of photons, as a new fundamental degree of freedom, has excited a great diversity of interest, because of a variety of emerging applications. Arbitrarily tunable OAM has gained much attention, but its creation remains still a tremendous challenge. We demonstrate the realization of well-controlled arbitrary OAM in both theory and experiment. We present the concept of general OAM, which extends the OAM carried by the scalar vortex field to the OAM carried by the azimuthally varying polarized vector field. The arbitrary OAM has the same characteristics as the well-defined integer OAM: intrinsic OAM, uniform local OAM and intensity ring, and propagation stability. The arbitrary OAM has unique natures: it is allowed to be flexibly tailored and the radius of the focusing ring can have various choices for a desired OAM, which are of great significance to the benefit of surprising applications of the arbitrary OAM.

  12. Influence of polarization extinction ratio on distributed polarization coupling detection

    Institute of Scientific and Technical Information of China (English)

    XU Tian-hua; TANG Feng; JING Wen-cai; ZHANG Hong-xia; JIA Da-gong; YU Chang-song; ZHOU Ge; ZHANG Yi-mo


    Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelsonin terferorneter. This technique usually requires that only one polarization mode is excited. However, in practical measurement,the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of theincident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.

  13. The Gravity Field of Mars From MGS, Mars Odyssey, and MRO Radio Science (United States)

    Genova, Antonio; Goossens, Sander; Lemoine, Frank G.; Mazarico, Erwan; Smith, David E.; Zuber, Maria T.


    The Mars Global Surveyor (MGS), Mars Odyssey (ODY), and Mars Reconnaissance Orbiter (MRO) missions have enabled NASA to conduct reconnaissance and exploration of Mars from orbit for sixteen consecutive years. These radio systems on these spacecraft enabled radio science in orbit around Mars to improve the knowledge of the static structure of the Martian gravitational field. The continuity of the radio tracking data, which cover more than a solar cycle, also provides useful information to characterize the temporal variability of the gravity field, relevant to the planet's internal dynamics and the structure and dynamics of the atmosphere [1]. MGS operated for more than 7 years, between 1999 and 2006, in a frozen sun-synchronous, near-circular, polar orbit with the periapsis at approximately 370 km altitude. ODY and MRO have been orbiting Mars in two separate sun-synchronous orbits at different local times and altitudes. ODY began its mapping phase in 2002 with the periapis at approximately 390 km altitude and 4-5pm Local Solar Time (LST), whereas the MRO science mission started in November 2006 with the periapis at approximately 255 km altitude and 3pm LST. The 16 years of radio tracking data provide useful information on the atmospheric density in the Martian upper atmosphere. We used ODY and MRO radio data to recover the long-term periodicity of the major atmospheric constituents -- CO2, O, and He -- at the orbit altitudes of these two spacecraft [2]. The improved atmospheric model provides a better prediction of the annual and semi-annual variability of the dominant species. Therefore, the inclusion of the recovered model leads to improved orbit determination and an improved gravity field model of Mars with MGS, ODY, and MRO radio tracking data.

  14. Orbital State Uncertainty Realism (United States)

    Horwood, J.; Poore, A. B.


    Fundamental to the success of the space situational awareness (SSA) mission is the rigorous inclusion of uncertainty in the space surveillance network. The *proper characterization of uncertainty* in the orbital state of a space object is a common requirement to many SSA functions including tracking and data association, resolution of uncorrelated tracks (UCTs), conjunction analysis and probability of collision, sensor resource management, and anomaly detection. While tracking environments, such as air and missile defense, make extensive use of Gaussian and local linearity assumptions within algorithms for uncertainty management, space surveillance is inherently different due to long time gaps between updates, high misdetection rates, nonlinear and non-conservative dynamics, and non-Gaussian phenomena. The latter implies that "covariance realism" is not always sufficient. SSA also requires "uncertainty realism"; the proper characterization of both the state and covariance and all non-zero higher-order cumulants. In other words, a proper characterization of a space object's full state *probability density function (PDF)* is required. In order to provide a more statistically rigorous treatment of uncertainty in the space surveillance tracking environment and to better support the aforementioned SSA functions, a new class of multivariate PDFs are formulated which more accurately characterize the uncertainty of a space object's state or orbit. The new distribution contains a parameter set controlling the higher-order cumulants which gives the level sets a distinctive "banana" or "boomerang" shape and degenerates to a Gaussian in a suitable limit. Using the new class of PDFs within the general Bayesian nonlinear filter, the resulting filter prediction step (i.e., uncertainty propagation) is shown to have the *same computational cost as the traditional unscented Kalman filter* with the former able to maintain a proper characterization of the uncertainty for up to *ten

  15. Precise Orbit Determination for ALOS (United States)

    Nakamura, Ryo; Nakamura, Shinichi; Kudo, Nobuo; Katagiri, Seiji


    The Advanced Land Observing Satellite (ALOS) has been developed to contribute to the fields of mapping, precise regional land coverage observation, disaster monitoring, and resource surveying. Because the mounted sensors need high geometrical accuracy, precise orbit determination for ALOS is essential for satisfying the mission objectives. So ALOS mounts a GPS receiver and a Laser Reflector (LR) for Satellite Laser Ranging (SLR). This paper deals with the precise orbit determination experiments for ALOS using Global and High Accuracy Trajectory determination System (GUTS) and the evaluation of the orbit determination accuracy by SLR data. The results show that, even though the GPS receiver loses lock of GPS signals more frequently than expected, GPS-based orbit is consistent with SLR-based orbit. And considering the 1 sigma error, orbit determination accuracy of a few decimeters (peak-to-peak) was achieved.

  16. High-capacity millimetre-wave communications with orbital angular momentum multiplexing. (United States)

    Yan, Yan; Xie, Guodong; Lavery, Martin P J; Huang, Hao; Ahmed, Nisar; Bao, Changjing; Ren, Yongxiong; Cao, Yinwen; Li, Long; Zhao, Zhe; Molisch, Andreas F; Tur, Moshe; Padgett, Miles J; Willner, Alan E


    One property of electromagnetic waves that has been recently explored is the ability to multiplex multiple beams, such that each beam has a unique helical phase front. The amount of phase front 'twisting' indicates the orbital angular momentum state number, and beams with different orbital angular momentum are orthogonal. Such orbital angular momentum based multiplexing can potentially increase the system capacity and spectral efficiency of millimetre-wave wireless communication links with a single aperture pair by transmitting multiple coaxial data streams. Here we demonstrate a 32-Gbit s(-1) millimetre-wave link over 2.5 metres with a spectral efficiency of ~16 bit s(-1) Hz(-1) using four independent orbital-angular momentum beams on each of two polarizations. All eight orbital angular momentum channels are recovered with bit-error rates below 3.8 × 10(-3). In addition, we demonstrate a millimetre-wave orbital angular momentum mode demultiplexer to demultiplex four orbital angular momentum channels with crosstalk less than -12.5 dB and show an 8-Gbit s(-1) link containing two orbital angular momentum beams on each of two polarizations.

  17. Decomposition of nuclear magnetic resonance spin-spin coupling constants into active and passive orbital contributions. (United States)

    Gräfenstein, Jürgen; Tuttle, Tell; Cremer, Dieter


    The theory of the J-OC-PSP (decomposition of J into orbital contributions using orbital currents and partial spin polarization) method is derived to distinguish between the role of active, passive, and frozen orbitals on the nuclear magnetic resonance (NMR) spin-spin coupling mechanism. Application of J-OC-PSP to the NMR spin-spin coupling constants of ethylene, which are calculated using coupled perturbed density functional theory in connection with the B3LYP hybrid functional and a [7s,6p,2d/4s,2p] basis set, reveal that the well-known pi mechanism for Fermi contact (FC) spin coupling is based on passive pi orbital contributions. The pi orbitals contribute to the spin polarization of the sigma orbitals at the coupling nuclei by mediating spin information between sigma orbitals (spin-transport mechanism) or by increasing the spin information of a sigma orbital by an echo effect. The calculated FC(pi) value of the SSCC (1)J(CC) of ethylene is 4.5 Hz and by this clearly smaller than previously assumed.

  18. Polarization measurement in the COMPASS polarized target

    CERN Document Server

    Kondo, K; Baum, G; Berglund, P; Doshita, N; Gautheron, F; Görtz, S; Hasegawa, T; Horikawa, N; Ishimoto, S; Iwata, T; Kisselev, Yu V; Koivuniemi, J H; Le Goff, J M; Magnon, A; Meyer, W; Reicherz, G; Matsuda, T


    Continuous wave nuclear magnetic resonance (NMR) is used to determine the target polarization in the COMPASS experiment. The system is made of the so-called Liverpool Q-meters, Yale-cards, and VME modules for data taking and system controlling. In 2001 the NMR coils were embedded in the target material, while in 2002 and 2003 the coils were mounted on the outer surface of the target cells to increase the packing factor of the material. Though the error of the measurement became larger with the outer coils than with the inner coils, we have performed stable measurements throughout the COMPASS run time for 3 years. The maximum polarization was +57% and -53% as the average in the target cells.

  19. Electron transport for a laser-irradiated quantum channel with Rashba spin-orbit coupling

    Institute of Scientific and Technical Information of China (English)

    Zhao Hua; Liao Wen-Hu; Zhou Guang-Hui


    We investigate theoretically the electron transport for a two-level quantum channel (wire) with Rashba spinorbit coupling under the irradiation of a longitudinally-polarized external laser field at low temperatures. Using the method of equation of motion for Keldysh nonequilibrium Green function, we examine the time-averaged spin polarized conductance for the system with photon polarization parallel to the wire direction. By analytical analysis and a few numerical examples, the interplay effects of the external laser field and the Rashba spin-orbit coupling on the spin-polarized conductance for the system are demonstrated and discussed. It is found that the longitudinally-polarized laser field can adjust the spin polarization rate and produce some photon sideband resonances of the conductance for the system.

  20. Orbital Eccrine Hidrocystoma

    Directory of Open Access Journals (Sweden)

    Deniz Marangoz


    Full Text Available A 29-year-old female patient presented with a painless mass on her upper eyelid medially. She noticed the mass 4 years earlier and it had increased in size over time. She had no diplopia, eyelid swelling, skin lesion overlying the mass, or visual disturbances. On ocular examination, eye movements and funduscopy were normal. The mass was movable and painless with palpation. Magnetic resonance imaging with contrast showed a 12x8x7 mm well-circumscribed cystic lesion with no contrast dye appearance. Surgical removal was performed delicately and no capsular rupture occured. Pathological examination revealed an eccrine hidrocystoma. Our aim is to underline that eccrine hidrocystoma should be included in differential diagnosis of orbital masses.

  1. Exploratory orbit analysis

    Energy Technology Data Exchange (ETDEWEB)

    Michelotti, L.


    Unlike the other documents in these proceedings, this paper is neither a scientific nor a technical report. It is, rather, a short personal essay which attempts to describe an Exploratory Orbit Analysis (EOA) environment. Analyzing the behavior of a four or six dimensional nonlinear dynamical system is at least as difficult as analyzing events in high-energy collisions; the consequences of doing it badly, or slowly, would be at least as devastating; and yet the level of effort and expenditure invested in the latter, the very attention paid to it by physicists at large, must be two orders of magnitude greater than that given to the former. It is difficult to choose the model which best explains the behavior of a physical device if one does not first understand the behavior of the available models. The time is ripe for the development of a functioning EOA environment, which I will try to describe in this paper to help us achieve this goal.

  2. Orbital science's 'Bermuda Triangle' (United States)

    Sherrill, Thomas J.


    The effects of a part of the inner Van Allen belt lying closest to the earth, known as the South Atlantic Anomaly (SAA) upon spacecraft including the Hubble Space Telescope (HST), are discussed. The area consists of positively charged ions and electrons from the Van Allen Belt which become trapped in the earth's dipole field. Contor maps representing the number of protons per square centimeter per second having energies greater than 10 million electron volts are presented. It is noted that the HST orbit causes it to spend about 15 percent of its time in the SAA, but that, unlike the experience with earlier spacecraft, the satellite's skin, internal structure, and normal electronic's packaging provides sufficient protection against eletrons, although some higher energy protons still get through. Various charged particle effects which can arise within scientific instruments including fluorescence, Cerenkov radiation, and induced radioactivity are described.

  3. Geology orbiter comparison study (United States)

    Cutts, J. A. J.; Blasius, K. R.; Davis, D. R.; Pang, K. D.; Shreve, D. C.


    Instrument requirements of planetary geology orbiters were examined with the objective of determining the feasibility of applying standard instrument designs to a host of terrestrial targets. Within the basic discipline area of geochemistry, gamma-ray, X-ray fluorescence, and atomic spectroscopy remote sensing techniques were considered. Within the discipline area of geophysics, the complementary techniques of gravimetry and radar were studied. Experiments using these techniques were analyzed for comparison at the Moon, Mercury, Mars and the Galilean satellites. On the basis of these comparative assessments, the adaptability of each sensing technique was judged as a basic technique for many targets, as a single instrument applied to many targets, as a single instrument used in different mission modes, and as an instrument capability for nongeoscience objectives.

  4. The conservation of orbital symmetry

    CERN Document Server

    Woodward, R B


    The Conservation of Orbital Symmetry examines the principle of conservation of orbital symmetry and its use. The central content of the principle was that reactions occur readily when there is congruence between orbital symmetry characteristics of reactants and products, and only with difficulty when that congruence does not obtain-or to put it more succinctly, orbital symmetry is conserved in concerted reaction. This principle is expected to endure, whatever the language in which it may be couched, or whatever greater precision may be developed in its application and extension. The book ope

  5. Homogeneous orbit closures and applications

    CERN Document Server

    Lindenstrauss, Elon


    We give new classes of examples of orbits of the diagonal group in the space of unit volume lattices in R^d for d > 2 with nice (homogeneous) orbit closures, as well as examples of orbits with explicitly computable but irregular orbit closures. We give Diophantine applications to the former, for instance we show that if x is the cubic root of 2 then for any y,z in R liminf |n|=0 (as |n| goes to infinity), where denotes the distance of a real number c to the integers.

  6. Orbit Alignment in Triple Stars (United States)

    Tokovinin, Andrei


    The statistics of the angle Φ between orbital angular momenta in hierarchical triple systems with known inner visual or astrometric orbits are studied. A correlation between apparent revolution directions proves the partial orbit alignment known from earlier works. The alignment is strong in triples with outer projected separation less than ∼50 au, where the average Φ is about 20^\\circ . In contrast, outer orbits wider than 1000 au are not aligned with the inner orbits. It is established that the orbit alignment decreases with the increasing mass of the primary component. The average eccentricity of inner orbits in well-aligned triples is smaller than in randomly aligned ones. These findings highlight the role of dissipative interactions with gas in defining the orbital architecture of low-mass triple systems. On the other hand, chaotic dynamics apparently played a role in shaping more massive hierarchies. The analysis of projected configurations and triples with known inner and outer orbits indicates that the distribution of Φ is likely bimodal, where 80% of triples have {{Φ }}< 70^\\circ and the remaining ones are randomly aligned.

  7. Observation of Interaction of Spin and Intrinsic Orbital Angular Momentum of Light

    CERN Document Server

    Vitullo, Dashiell L P; Gregg, Patrick; Smith, Roger A; Reddy, Dileep V; Ramachandran, Siddharth; Raymer, Michael G


    Spin and intrinsic orbital angular momentum interaction of light is observed, as evidenced by length-dependent rotations of both spatial patterns and optical polarization in an isotropic optical fiber. The distinction between intrinsic and extrinsic orbital angular momentum (as seen in helically coiled fiber) is made clear by controllable excitation of a small number of optical modes in a straight, few-mode fiber.

  8. Subwave spikes of the orbital angular momentum of the vortex-beams in a uniaxial crystal

    CERN Document Server

    Fadeyeva, T; Rubass, A; Zinov'ev, A; Konovalenko, V; Volyar, A


    We have theoretically predicted the gigantic spikes of the orbital angular momentum caused by the conversion processes of the centered optical vortex in the circularly polarized components of the elliptic vortex beam propagating perpendicular to the crystal optical axis. We have experimentally observed the conversion process inside the subwave deviations of the crystal length. We have found that the total orbital angular momentum of the wave beam is conserved.

  9. Study of the propagation and detection of the orbital angular momentum of light for astrophysical applications


    Sponselli, Anna


    The aim of this work is to study the propagation of orbital angular momentum (OAM) of light for astrophysical applications and a method for OAM detection with optical telescopes. The thesis deals with the study of the orbital angular momentum (OAM) as a new observable for astronomers, which could give additional information with respect to those already inferred from the analysis of the intensity, frequency and polarization of light. Indeed, the main purpose of this work is to highlight th...

  10. The role of Rashba spin-orbit coupling in valley-dependent transport of Dirac fermions (United States)

    Hasanirok, Kobra; Mohammadpour, Hakimeh


    At this work, spin- and valley-dependent electron transport through graphene and silicene layers are studied in the presence of Rashba spin- orbit coupling. We find that the transport properties of the related ferromagnetic/normal/ferromagnetic structure depend on the relevant parameters. A fully valley- and spin- polarized current is obtained. As another result, Rashba spin-orbit interaction plays important role in controlling the transmission characteristics.

  11. Subwave spikes of the orbital angular momentum of the vortex beams in a uniaxial crystal (United States)

    Fadeyeva, T.; Alexeyev, C.; Rubass, A.; Zinov'Ev, A.; Konovalenko, V.; Volyar, A.


    We have theoretically predicted the gigantic spikes of the orbital angular momentum caused by the conversion processes of the centered optical vortex in the circularly polarized components of the elliptic vortex beam propagating perpendicular to the crystal optical axis. We have experimentally observed the conversion process inside the subwave deviations of the crystal length. We have found that the total orbital angular momentum of the wave beam is conserved.

  12. Diels−Alder Reactions of Acyclic 2-Azadienes: A Semiempirical Molecular Orbital Study


    Teresa M. V. D. Pinho e Melo; Fausto, Rui; Gonsalves, António M. d'A. Rocha


    Molecular orbital calculations (AM1) have been performed to obtain the frontier orbitals' (HOMO and LUMO) energies and polarization of a series of acyclic 2-azadienes. The results are used to rationalize the reactivity of the compounds studied with both electron-rich and electron-deficient dienophiles as well as the observed regioselectivity of the corresponding Diels−Alder reactions.

  13. Exoplanet's Atmospheres Characteristics vs. Exoplanet's Orbital Elements (United States)

    Molaverdikhani, Karan


    400 years after Galileo Galilei was detected Jovian system, we know about 400 exoplanets in other stellar systems. But we identify just about their major properties like some of orbital elements, planet's radii or density. Also, there are many scientists who interested in searching for life or habitability on these planets. They are working in different ways such as planetary formation, planetary orbital stability or immigration, HabStars, composition of atmospheres, most probable zone in sky for exoplanets detection, etc. In this research we distinct and defined some main characteristics of terrestrial planet's atmospheres with surveying on solar system's planets and matching with current theorems on atmosphere formation. On the other hand, we were modeled Mars, Venus, Titan, single Hadley Earth and virtual Venus with different tilt angel (applying Global Circulation Modeling) to finding a critical limit on Polar Vortex formation in our last research. With extension this method on hypothetical terrestrial planets in constraint mass between 0.7 to 2.5 Earth's mass on Green Belt and applying host stars from 0.5 to 1.5 Sun's mass, we found some limitations on planet's atmosphere formation and estimation values of atmosphere's main characteristics.

  14. Time Domain Induced Polarization

    DEFF Research Database (Denmark)

    Fiandaca, Gianluca; Auken, Esben; Christiansen, Anders Vest


    Time-domain-induced polarization has significantly broadened its field of reference during the last decade, from mineral exploration to environmental geophysics, e.g., for clay and peat identification and landfill characterization. Though, insufficient modeling tools have hitherto limited the use...... of time-domaininduced polarization for wider purposes. For these reasons, a new forward code and inversion algorithm have been developed using the full-time decay of the induced polarization response, together with an accurate description of the transmitter waveform and of the receiver transfer function......%. Furthermore, the presence of low-pass filters in time-domain-induced polarization instruments affects the early times of the acquired decays (typically up to 100 ms) and has to be modeled in the forward response to avoid significant loss of resolution. The developed forward code has been implemented in a 1D...

  15. Dynamic nuclear spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H.B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany)


    Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

  16. Invariants of polarization transformations. (United States)

    Sadjadi, Firooz A


    The use of polarization-sensitive sensors is being explored in a variety of applications. Polarization diversity has been shown to improve the performance of the automatic target detection and recognition in a significant way. However, it also brings out the problems associated with processing and storing more data and the problem of polarization distortion during transmission. We present a technique for extracting attributes that are invariant under polarization transformations. The polarimetric signatures are represented in terms of the components of the Stokes vectors. Invariant algebra is then used to extract a set of signature-related attributes that are invariant under linear transformation of the Stokes vectors. Experimental results using polarimetric infrared signatures of a number of manmade and natural objects undergoing systematic linear transformations support the invariancy of these attributes.


    National Research Council Canada - National Science Library

    L. D. Tondiy; O. L. Tondiy; I. V. Kas; O. V. Zemlyana; O. L. Zakrevska; V. O. Zhuravliev


    The data on polarized light (PS) - a new promising treatment, rehabilitation and prevention, which took its deserved place among the known therapeutic physical factors and may even compete with laser radiation of low and LED therapy...

  18. Cell Polarity in Yeast. (United States)

    Chiou, Jian-Geng; Balasubramanian, Mohan K; Lew, Daniel J


    A conserved molecular machinery centered on the Cdc42 GTPase regulates cell polarity in diverse organisms. Here we review findings from budding and fission yeasts that reveal both a conserved core polarity circuit and several adaptations that each organism exploits to fulfill the needs of its lifestyle. The core circuit involves positive feedback by local activation of Cdc42 to generate a cluster of concentrated GTP-Cdc42 at the membrane. Speciesspecific pathways regulate the timing of polarization during the cell cycle, as well as the location and number of polarity sites. Expected final online publication date for the Annual Review of Cell and Developmental Biology Volume 33 is October 6, 2017. Please see for revised estimates.

  19. Coordenadas polares: curvas maravillosas


    Norberto Jaime Chau Pérez; Roy Wil Sánchez Gutiérrez


    Se presenta una actividad colaborativa en la que se trabaja el tema coordenadas polares. Se presentan los objetivos de aprendizaje, el desarrollo de la actividad, los conocimientos previos necesarios y recomendaciones para una aplicación posterior.

  20. Political Competition and Polarization

    DEFF Research Database (Denmark)

    Schultz, Christian

    This paper considers political competition and the consequences of political polarization when parties are better informed about how the economy functions than voters are. Specifically, parties know the cost producing a public good, voters do not. An incumbent's choice of policy acts like a signal...... for costs before an upcoming election. It is shown that the more polarized the political parties the more distorted the incumbent's policy choice....

  1. New orbit correction method uniting global and local orbit corrections (United States)

    Nakamura, N.; Takaki, H.; Sakai, H.; Satoh, M.; Harada, K.; Kamiya, Y.


    A new orbit correction method, called the eigenvector method with constraints (EVC), is proposed and formulated to unite global and local orbit corrections for ring accelerators, especially synchrotron radiation(SR) sources. The EVC can exactly correct the beam positions at arbitrarily selected ring positions such as light source points, simultaneously reducing closed orbit distortion (COD) around the whole ring. Computer simulations clearly demonstrate these features of the EVC for both cases of the Super-SOR light source and the Advanced Light Source (ALS) that have typical structures of high-brilliance SR sources. In addition, the effects of errors in beam position monitor (BPM) reading and steering magnet setting on the orbit correction are analytically expressed and also compared with the computer simulations. Simulation results show that the EVC is very effective and useful for orbit correction and beam position stabilization in SR sources.

  2. PyORBIT: A Python Shell For ORBIT

    Energy Technology Data Exchange (ETDEWEB)

    Jean-Francois Ostiguy; Jeffrey Holmes


    ORBIT is code developed at SNS to simulate beam dynamics in accumulation rings and synchrotrons. The code is structured as a collection of external C++ modules for SuperCode, a high level interpreter shell developed at LLNL in the early 1990s. SuperCode is no longer actively supported and there has for some time been interest in replacing it by a modern scripting language, while preserving the feel of the original ORBIT program. In this paper, we describe a new version of ORBIT where the role of SuperCode is assumed by Python, a free, well-documented and widely supported object-oriented scripting language. We also compare PyORBIT to ORBIT from the standpoint of features, performance and future expandability.

  3. Orbital Chondroma: A rare mesenchymal tumor of orbit

    Directory of Open Access Journals (Sweden)

    Ruchi S Kabra


    Full Text Available While relatively common in the skeletal system, cartilaginous tumors are rarely seen originating from the orbit. Here, we report a rare case of an orbital chondroma. A 27-year-old male patient presented with a painless hard mass in the superonasal quadrant (SNQ of left orbit since 3 months. On examination, best-corrected visual acuity of both eyes was 20/20, with normal anterior and posterior segment with full movements of eyeballs and normal intraocular pressure. Computerized tomography scan revealed well defined soft tissue density lesion in SNQ of left orbit. Patient was operated for anteromedial orbitotomy under general anesthesia. Mass was excised intact and sent for histopathological examination (HPE. HPE report showed lobular aggregates of benign cartilaginous cells with mild atypia suggesting of benign cartilaginous tumor - chondroma. Very few cases of orbital chondroma have been reported in literature so far.

  4. Quantum teleportation in the spin-orbit variables of photon pairs

    CERN Document Server

    Khoury, A Z


    We propose a polarization to orbital angular momentum teleportation scheme using entangled photon pairs generated by spontaneous parametric down conversion. By making a joint detection of the polarization and angular momentum parity of a single photon, we are able to detect all the Bell-states and perform, in principle, perfect teleportation from a discrete to a continuous system using minimal resources. The proposed protocol implementation demands experimental resources that are currently available in quantum optics laboratories.

  5. Spin Interference in Rectangle Loop Based on Rashba and Dresselhaus Spin-Orbit Interactions

    Institute of Scientific and Technical Information of China (English)

    NI Jia-Ting; LIANG Xiao-Wan; CHEN Bin; T.Koga


    We demonstrate the amplitude and spin polarization of AAS oscillation changing with Rashba spin-orbit interaction(SOI)and Dresselhaus SOI.The amplitude and spin polarization of AB oscillation changing with Rashba SOI and Dresselhaus SOI are demonstrated as well.The ideal quasi-one-dimensional square loop does not exist in reality,therefore to match the experiment better we should consider the shape of the rectangle loop in theory.

  6. Spin-Orbit Interaction of a Photon in AN Inhomogeneous Medium (United States)

    Liberman, V. S.; Zel'Dovich, B. Ya.

    The following sections are included: * Introduction * Transverse Shift of the Circularly Polarized Beam (CPB) due to Refraction * Differential Equations for a Trajectory and Polarization of the Ray. Hamilton's Form of the Equations * Optical Magnus Effect in a Graded-Index Waveguide * Optical Ping-Pong Effect in a Step-Like Index Waveguide * Paraxial Approximation for Maxwell's Equations * Spin-Orbit Corrections to the Paraxial Approximation: Hermitian Interaction Hamiltonian * The Wave Description of the Optical Magnus Effect * Conclusion * Acknowledgement * References

  7. Valence Virtual Orbitals: An Unambiguous ab Initio Quantification of the LUMO Concept. (United States)

    Schmidt, Michael W; Hull, Emily A; Windus, Theresa L


    Many chemical concepts hinge on the notion of an orbital called the lowest unoccupied molecular orbital, or LUMO. This hypothetical orbital and the much more concrete highest occupied molecular orbital (HOMO) constitute the two "frontier orbitals", which rationalize a great deal of chemistry. A viable LUMO candidate should have a sensible energy value, a realistic shape with amplitude on those atoms where electron attachment or reduction or excitation processes occur, and often an antibonding correspondence to one of the highest occupied MOs. Unfortunately, today's quantum chemistry calculations do not yield useful empty orbitals. Instead, the empty canonical orbitals form a large sea of orbitals, where the interesting valence antibonds are scrambled with the basis set's polarization and diffuse augmentations. The LUMO is thus lost within a continuum associated with a detached electron, as well as many Rydberg excited states. A suitable alternative to the canonical orbitals is proposed, namely, the valence virtual orbitals. VVOs are found by a simple algorithm based on singular value decomposition, which allows for the extraction of all valence-like orbitals from the large empty canonical orbital space. VVOs are found to be nearly independent of the working basis set. The utility of VVOs is demonstrated for construction of qualitative MO diagrams, for prediction of valence excited states, and as starting orbitals for more sophisticated calculations. This suggests that VVOs are a suitable realization of the LUMO, LUMO + 1, ... VVO generation requires no expert knowledge, as the number of VVOs sought is found by counting s-block atoms as having only a valence s orbital, transition metals as having valence s and d, and main group atoms as being valence s and p elements. Closed shell, open shell, or multireference wave functions and elements up to xenon may be used in the present program.

  8. Polar Warming Drivers (United States)

    McDunn, T. L.; Bougher, S. W.; Mischna, M. A.; Murphy, J. R.


    Polar warming is a dynamically induced temperature enhancement over mid-to-high latitudes that results in a reversed (poleward) meridional temperature gradient. This phenomenon was recently characterized over the 40-90 km altitude region [1] based on nearly three martian years of Mars Climate Sounder observations [2, 3]. Here we investigate which forcing mechanisms affect the magnitude and distribution of the observed polar warming by conducting simulations with the Mars Weather Research and Forecasting General Circulation Model [4, 5]. We present simulations confirming the influence topography [6] and dust loading [e.g., 7] have upon polar warming. We then present simulations illustrating the modulating influence gravity wave momentum deposition exerts upon polar warming, consistent with previous modeling studies [e.g., 8]. The results of this investigation suggest the magnitude and distribution of polar warming in the martian middle atmosphere is modified by gravity wave activity and that the characteristics of the gravity waves that most significantly affect polar warming vary with season. References: [1] McDunn, et al., 2012 (JGR), [2]Kleinböhl, et al., 2009 (JGR), [3] Kleinböhl, et al., 2011 (JQSRT), [4] Richardson, et al., 2007 (JGR), [5] Mischna, et al., 2011 (Planet. Space Sci.), [6] Richardson and Wilson, 2002 (Nature), [7] Haberle, et al., 1982 (Icarus), [8] Barnes, 1990 (JGR).

  9. Polarization properties of linearly polarized parabolic scaling Bessel beams (United States)

    Guo, Mengwen; Zhao, Daomu


    The intensity profiles for the dominant polarization, cross polarization, and longitudinal components of modified parabolic scaling Bessel beams with linear polarization are investigated theoretically. The transverse intensity distributions of the three electric components are intimately connected to the topological charge. In particular, the intensity patterns of the cross polarization and longitudinal components near the apodization plane reflect the sign of the topological charge.

  10. The polar Kerr effect in superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Robbins, Joshua; Annett, James F.; Gradhand, Martin [University of Bristol (United Kingdom)


    The polar Kerr effect is an optical phenomenon which arises in states with broken time-reversal symmetry. This effect has recently been observed in a series of unconventional superconductors, including the layered perovskite compound Sr{sub 2}RuO{sub 4}. Confirmation of a Kerr signal below T{sub c} supports the hypothesis of chiral p-wave superconductivity in this material. However, the nature of the unconventional superconducting state remains a source of controversy. Here, we present calculations for the chiral superconducting state including spin-orbit coupling (SOC) by extending the three dimensional, multiband model considered previously. SOC was found to induce strong mixing of the orbital characters within the bandstructure. This mixing is essential for the existence of the polar Kerr effect and the large increase due to SOC has a significant influence on the frequency dependence of the predicted Kerr signal. We will extend and apply the model to other unconventional superconductors which have displayed the Kerr effect in recent years. This will allow a detailed study of the symmetry properties of these systems and will provide valuable insight into the pairing mechanism of superconductors.

  11. Diplopia and orbital wall fractures

    NARCIS (Netherlands)

    Boffano, P.; Roccia, F.; Gallesio, C.; Karagozoglu, K.H.; Forouzanfar, T.


    Diplopia is a symptom that is frequently associated with orbital wall fractures. The aim of this article was to present the incidence and patterns of diplopia after orbital wall blow-out fractures in 2 European centers, Turin and Amsterdam, and to identify any correlation between this symptom and su

  12. [Enophthalmos in an orbital tumor]. (United States)

    Szabo, Bianca; Szabo, I; Nicula, Cristina; Popescu, Livia Adriana


    Enophtalmus is an unusual sign of the orbital tumors often represented by proptosis. One patient with enophtalmus and intraorbital tumor and aplasy is presented. The treatment of choice of orbital tumor is complete surgical excision and careful follow-up. Considering the more aggressive course followed by recurrent tumor, correct diagnosis and management is essential.

  13. Diffractive molecular-orbital tomography (United States)

    Zhai, Chunyang; Zhu, Xiaosong; Lan, Pengfei; Wang, Feng; He, Lixin; Shi, Wenjing; Li, Yang; Li, Min; Zhang, Qingbin; Lu, Peixiang


    High-order-harmonic generation in the interaction of femtosecond lasers with atoms and molecules opens the path to molecular-orbital tomography and to probe the electronic dynamics with attosecond-Ångström resolutions. Molecular-orbital tomography requires both the amplitude and phase of the high-order harmonics. Yet the measurement of phases requires sophisticated techniques and represents formidable challenges at present. Here we report a scheme, called diffractive molecular-orbital tomography, to retrieve the molecular orbital solely from the amplitude of high-order harmonics without measuring any phase information. We have applied this method to image the molecular orbitals of N2, CO2, and C2H2 . The retrieved orbital is further improved by taking account the correction of Coulomb potential. The diffractive molecular-orbital tomography scheme, removing the roadblock of phase measurement, significantly simplifies the molecular-orbital tomography procedure and paves an efficient and robust way to the imaging of more complex molecules.

  14. GridOrbit public display

    DEFF Research Database (Denmark)

    Ramos, Juan David Hincapie; Tabard, Aurélien; Bardram, Jakob


    We introduce GridOrbit, a public awareness display that visualizes the activity of a community grid used in a biology laboratory. This community grid executes bioin-formatics algorithms and relies on users to donate CPU cycles to the grid. The goal of GridOrbit is to create a shared awareness about...

  15. Diplopia and orbital wall fractures

    NARCIS (Netherlands)

    Boffano, P.; Roccia, F.; Gallesio, C.; Karagozoglu, K.H.; Forouzanfar, T.


    Diplopia is a symptom that is frequently associated with orbital wall fractures. The aim of this article was to present the incidence and patterns of diplopia after orbital wall blow-out fractures in 2 European centers, Turin and Amsterdam, and to identify any correlation between this symptom and

  16. Low Earth Orbiter: Terminal (United States)

    Kremer, Steven E.; Bundick, Steven N.


    In response to the current government budgetary environment that requires the National Aeronautics and Space Administration (NASA) to do more with less, NASA/Goddard Space Flight Center's Wallops Flight Facility has developed and implemented a class of ground stations known as a Low Earth Orbiter-Terminal (LEO-T). This development thus provides a low-cost autonomous ground tracking service for NASA's customers. More importantly, this accomplishment provides a commercial source to spacecraft customers around the world to purchase directly from the company awarded the NASA contract to build these systems. A few years ago, NASA was driven to provide more ground station capacity for spacecraft telemetry, tracking, and command (TT&C) services with a decreasing budget. NASA also made a decision to develop many smaller, cheaper satellites rather than a few large spacecraft as done in the past. In addition, university class missions were being driven to provide their own TT&C services due to the increasing load on the NASA ground-tracking network. NASA's solution for this ever increasing load was to use the existing large aperture systems to support those missions requiring that level of performance and to support the remainder of the missions with the autonomous LEO-T systems. The LEO-T antenna system is a smaller, cheaper, and fully autonomous unstaffed system that can operate without the existing NASA support infrastructure. The LEO-T provides a low-cost, reliable space communications service to the expanding number of low-earth orbiting missions around the world. The system is also fostering developments that improve cost-effectiveness of autonomous-class capabilities for NASA and commercial space use. NASA has installed three LEO-T systems. One station is at the University of Puerto Rico, the second system is installed at the Poker Flat Research Range near Fairbanks, Alaska, and the third system is installed at NASA's Wallops Flight Facility in Virginia. This paper

  17. Polarized Light Microscopy (United States)

    Frandsen, Athela F.


    Polarized light microscopy (PLM) is a technique which employs the use of polarizing filters to obtain substantial optical property information about the material which is being observed. This information can be combined with other microscopy techniques to confirm or elucidate the identity of an unknown material, determine whether a particular contaminant is present (as with asbestos analysis), or to provide important information that can be used to refine a manufacturing or chemical process. PLM was the major microscopy technique in use for identification of materials for nearly a century since its introduction in 1834 by William Fox Talbot, as other techniques such as SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared spectroscopy), XPD (X-ray Powder Diffraction), and TEM (Transmission Electron Microscopy) had not yet been developed. Today, it is still the only technique approved by the Environmental Protection Agency (EPA) for asbestos analysis, and is often the technique first applied for identification of unknown materials. PLM uses different configurations in order to determine different material properties. With each configuration additional clues can be gathered, leading to a conclusion of material identity. With no polarizing filter, the microscope can be used just as a stereo optical microscope, and view qualities such as morphology, size, and number of phases. With a single polarizing filter (single polars), additional properties can be established, such as pleochroism, individual refractive indices, and dispersion staining. With two polarizing filters (crossed polars), even more can be deduced: isotropy vs. anisotropy, extinction angle, birefringence/degree of birefringence, sign of elongation, and anomalous polarization colors, among others. With the use of PLM many of these properties can be determined in a matter of seconds, even for those who are not highly trained. McCrone, a leader in the field of polarized light microscopy, often

  18. Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

    KAUST Repository

    Zhang, Qian


    We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom.

  19. Video Orbits of the Geminids (United States)

    Hajdukova, M.


    Geminid meteoroids, observed by the video technique, were analysed with the aim of determining the actual dispersion of their reciprocal semimajor axes 1/a within the stream. Orbits were selected from the European Video Meteor Network Database, EDMOND, (Kornos et al., 2013), from the SonotaCo Shower Catalogue (SonotaCo, 2009), and from the Czech Catalogue of Video Meteor Orbits (Koten et al., 2003). The observed orbital dispersion, including the measurement errors, was compared with that obtained from the precisely-reduced photographic orbits of Geminids from the IAU Meteor Data Center (Lindblad et al., 2003). In this paper, we concentrate on the influence of errors on the orbital dispersion. The size and distribution of observational errors determined from the long-period meteoroid streams (Hajdukova 2013), were applied to determine the real dispersion within this short-period meteoroid stream. The observed dispersions, described by the median absolute deviation in terms of 1/a, range from 0.041 to 0.050 1/au. The deviation of the median reciprocal semimajor axis from the parent (3200) Phaethon, obtained from Japanese video orbits, is 0.009 1/au, and that from the EDMOND data 0.01 1/au. This deviation obtained from the photographic orbits of the IAU Meteor Data Center was significantly greater (Hajdukova 2009). Similar results were obtained from the Czech Video Orbits Catalogue, where the value is 0.05 1/au. The investigation showed that semimajor axes of meteor orbits in both the SonotaCo and EDMOND datasets are systematically biased as a consequence of the method used for the video orbit determination, probably because corrections for atmospheric deceleration were either incorrectly made or were not done at all. Thus, the determined heliocentric velocities are underestimated, and the semimajor axes medians shifted towards smaller values. The observed distributions in 1/a from these video data become biased towards higher values of 1/a. The orbits of the Geminid

  20. [Polar and non polar notations of refraction]. (United States)

    Touzeau, O; Gaujoux, T; Costantini, E; Borderie, V; Laroche, L


    Refraction can be expressed by four polar notations which correspond to four different combinations of spherical or cylindrical lenses. Conventional expressions of refraction (plus and minus cylinder notation) are described by sphere, cylinder, and axis. In the plus cylinder notation, the axis visualizes the most powerful meridian. The axis usually corresponds to the bow tie axis in curvature maps. Plus cylinder notation is also valuable for all relaxing procedures (i.e., selective suture ablation, arcuate keratotomy, etc.). In the cross-cylinder notation, two orthogonal cylinders can describe (without the sphere component) the actual refraction of both the principal meridians. This notation must be made before performing the vertex calculation. Using an association of a Jackson cross-cylinder and a spherical equivalent, refraction can be broken down into two pure components: astigmatism and sphere. All polar notations of refraction may perfectly characterize a single refraction but are not suitable for statistical analysis, which requires nonpolar expression. After doubling the axis, a rectangular projection breaks down the Jackson cross-cylinder, which has a polar axis, into two Jackson cross-cylinders on the 0 degrees /90 degrees and 45 degrees /135 degrees axis. This procedure results in the loss of the directional nature of the data. Refraction can be written in a nonpolar notation by three rectangular coordinates (x,y,z), which can also represent the spherocylinder by one point in a dioptric space. These three independent (orthogonal) variables have a concrete optical significance: a spherical component, a direct/inverse (WTR/ATR) component, and an oblique component of the astigmatism. Finally, nonpolar notations are useful for statistical analysis and graphical representation of refraction.

  1. Measuring Scars of Periodic Orbits

    CERN Document Server

    Kaplan, L


    The phenomenon of periodic orbit scarring of eigenstates of classically chaotic systems is attracting increasing attention. Scarring is one of the most important ``corrections'' to the ideal random eigenstates suggested by random matrix theory. This paper discusses measures of scars and in so doing also tries to clarify the concepts and effects of eigenfunction scarring. We propose a new, universal scar measure which takes into account an entire periodic orbit and the linearized dynamics in its vicinity. This measure is tuned to pick out those structures which are induced in quantum eigenstates by unstable periodic orbits and their manifolds. It gives enhanced scarring strength as measured by eigenstate overlaps and inverse participation ratios, especially for longer orbits. We also discuss off-resonance scars which appear naturally on either side of an unstable periodic orbit.

  2. The 2009 Mars Telecommunications Orbiter (United States)

    Wilson, G. R.; Depaula, R.; Diehl, R. E.; Edwards, C. D.; Fitzgerald, R. J.; Franklin, S. F.; Gibbs, R. G.; Kerridge, S. A.; Komarek, T. A.; Noreen, G. K.

    The first spacecraft with a primary function of providing communication links while orbiting a foreign planet has begun development for a launch in 2009. NASA's Mars Telecommunications Orbiter would use three radio bands to magnify the benefits of other future Mars missions and enable some types of missions otherwise impractical. It would serve as the Mars hub for a growing interplanetary Internet. And it would pioneer the use of planet-to-planet laser communications to demonstrate the possibility for even great networking capabilities in the future. During its nearly 10-year mission in orbit, Mars Telecommunications Orbiter would aid navigation of arriving spacecraft to their martian landing sites and monitor critical events during landings and orbit insertions. In addition, it would enable data-transmission volumes great enough to bring a virtual Mars presence to the public through a range of Internet and video features.

  3. When measured spin polarization is not spin polarization (United States)

    Dowben, P. A.; Wu, Ning; Binek, Christian


    Spin polarization is an unusually ambiguous scientific idiom and, as such, is rarely well defined. A given experimental methodology may allow one to quantify a spin polarization but only in its particular context. As one might expect, these ambiguities sometimes give rise to inappropriate interpretations when comparing the spin polarizations determined through different methods. The spin polarization of CrO2 and Cr2O3 illustrate some of the complications which hinders comparisons of spin polarization values.

  4. Polarized nuclear target based on parahydrogen induced polarization

    Energy Technology Data Exchange (ETDEWEB)

    D. Budker, M.P. Ledbetter, S. Appelt, L.S. Bouchard, B. Wojtsekhowski


    We discuss a novel concept of a polarized nuclear target for accelerator fixed-target scattering experiments, which is based on parahydrogen induced polarization (PHIP). One may be able to reach a 33% free-proton polarization in the ethane molecule. The potential advantages of such a target include operation at zero magnetic field, fast ({approx}100 HZ) polarization oscillation (akin to polarization reversal), and operation with large intensity of an electron beam.

  5. Halo orbit to science orbit captures at planetary moons (United States)

    Bokelmann, Kevin A.; Russell, Ryan P.


    Ballisticly connecting halo orbits to science orbits in the circular-restricted three-body problem is investigated. Two classes of terminal science orbits are considered: low-altitude, tight orbits that are deep in the gravity well of the secondary body, and high-altitude, loose orbits that are strongly perturbed by the gravity of the primary body. General analytic expressions are developed to provide a minimum bound on impulse cost in both the circular restricted and the Hill's approximations. The equations are applied to a broad range of planetary moons, providing a mission design reference. Systematic grid search methods are developed to numerically find feasible transfers from halo orbits at Europa, confirming the analytical lower bound formulas. The two-impulse capture options in the case of Europa reveal a diverse set of potential solutions. Tight captures result in maneuver costs of 425-550 m/s while loose captures are found with costs as low as 30 m/s. The terminal orbits are verified to avoid escape or impact for at least 45 days.

  6. VSOP-2 Orbit Determination (United States)

    Takeuchi, H.; VSOP-2 Orbit Determination Sub-Working Group


    Precise orbit determination (POD) is a key factor to enable phase referencing observations with Astro-G. A POD accuracy of 30 cm is required for efficient X-band phase referencing observations, accuracy of 6 cm for K-band observations, and accuracy of 3 cm for Q-band observations. For the POD, Astro-G will be equipped with a GPS/Galileo receiver and a SLR (Satellite Laser Ranging) retroreflector array. Four POD antennas will be equipped on four sides of the satellite body, to cover all directions. The SLR will be used as a complement to the GPS at middle-to-high altitude. Because the refroreflector array should always face to the Earth direction, it will be set up on the Ka-link antenna gimbal. The most significant perturbing force for the Astro-G is solar radiation pressure (SRP). The reflectivity of each surface component should be preliminary measured in detail to model the SRP. The estimated achievable POD accuracy at apogee is 10 ˜ 30 cm in nominal case. Phase referencing observations in K- or Q-band can be performed if the enough amount of SLR tracking data can be obtained at high altitudes.

  7. Cylindrically Polarized Nondiffracting Optical Pulses

    CERN Document Server

    Ornigotti, Marco; Szameit, Alexander


    We extend the concept of radially and azimuthally polarized optical beams to the polychromatic domain by introducing cylindrically polarized nondiffracting optical pulses. In particular, we discuss in detail the case of cylindrically polarized X-waves, both in the paraxial and nonparaxial regime. The explicit expressions for the electric and magnetic fields of cylindrically polarized X-waves is also reported.

  8. Sequential Polarity-Reversing Circuit (United States)

    Labaw, Clayton C.


    Proposed circuit reverses polarity of electric power supplied to bidirectional dc motor, reversible electro-mechanical actuator, or other device operating in direction depending on polarity. Circuit reverses polarity each time power turned on, without need for additional polarity-reversing or direction signals and circuitry to process them.

  9. Spin-polarized photoemission from SiGe heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, A.; Bottegoni, F.; Isella, G.; Cecchi, S.; Chrastina, D.; Finazzi, M.; Ciccacci, F. [LNESS-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy)


    We apply the principles of Optical Orientation to measure by Mott polarimetry the spin polarization of electrons photoemitted from different group-IV heterostructures. The maximum measured spin polarization, obtained from a Ge/Si{sub 0.31}Ge{sub 0.69} strained film, undoubtedly exceeds the maximum value of 50% attainable in bulk structures. The explanation we give for this result lies in the enhanced band orbital mixing between light hole and split-off valence bands as a consequence of the compressive strain experienced by the thin Ge layer.

  10. Generation and dynamics of optical beams with polarization singularities

    CERN Document Server

    Cardano, Filippo; Marrucci, Lorenzo; de Lisio, Corrado; Santamato, Enrico


    We present a convenient method to generate vector beams of light having polarization singularities on their axis, via partial spin-to-orbital angular momentum conversion in a suitably patterned liquid crystal cell. The resulting polarization patterns exhibit a C-point on the beam axis and an L-line loop around it, and may have different geometrical structures such as \\qo{lemon}, \\qo{star}, and \\qo{vortex}. Our generation method allows us to control the radius of L-line loop around the central C-point. Moreover, we investigate the free-air propagation of these fields across a Rayleigh range.

  11. Generation and dynamics of optical beams with polarization singularities. (United States)

    Cardano, Filippo; Karimi, Ebrahim; Marrucci, Lorenzo; de Lisio, Corrado; Santamato, Enrico


    We present a convenient method to generate vector beams of light having polarization singularities on their axis, via partial spin-to-orbital angular momentum conversion in a suitably patterned liquid crystal cell. The resulting polarization patterns exhibit a C-point on the beam axis and an L-line loop around it, and may have different geometrical structures such as "lemon", "star", and "spiral". Our generation method allows us to control the radius of L-line loop around the central C-point. Moreover, we investigate the free-air propagation of these fields across a Rayleigh range.

  12. Numerical simulation study on spin resonant depolarization due to spin-orbit coupling

    Institute of Scientific and Technical Information of China (English)

    Lan Jie-Qin; Xu Hong-Liang


    The spin polarization phenomenon in lepton circular accelerators had been known for many years.It provides a new approach for physicists to study the spin feature of fundamental particles and the dynamics of spin-orbit coupling,such as spin resonances.We use numerical simulation to study the features of spin under the modulation of orbital motion in an electron storage ring.The various cases of depolarization due to spin-orbit coupling through an emitting photon and misalignment of magnets in the ring are discussed.

  13. Measurement of Gravitational Spin-Orbit Coupling in a Binary Pulsar System (United States)

    Stairs, I. H.; Thorsett. S. E.; Arzoumanian, Z.


    In relativistic gravity, a spinning pulsar will precess as it orbits a compact companion star. We have measured the effect of such precession on the average shape and polarization of the radiation from PSR B1534+12. We have also detected, with limited precision, special-relativistic aberration of the revolving pulsar beam due to orbital motion. Our observations fix the system geometry, including the misalignment between the spin and orbital angular momenta, and yield a measurement of the precession timescale consistent with the predictions of General Relativity.

  14. Hydrogenoid orbitals revisited: From Slater orbitals to Coulomb Sturmians

    Indian Academy of Sciences (India)

    Danilo Calderini; Simonetta Cavalli; Cecilia Coletti; Gaia Grossi; Vincenzo Qquilanti


    The simple connection between the Slater orbitals, venerable in quantum chemistry, and the Coulomb Sturmian orbitals, more recently employed in atomic and molecular physics, is pointed out explicitly in view of the renewed interest in both as basis sets in applied quantum mechanics. Research in Slater orbitals mainly concerns multicentre, many-body integrals, whereas that on Sturmians exploits their orthonormality and completeness with no need of continuum states. An account of recent progress is outlined, also with reference to relationships between the two basis sets, and with the momentum space and hyperspherical harmonics representations.

  15. Polarization twist in perovskite ferrielectrics. (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro


    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of 'polarization twist', which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms.

  16. Polarization twist in perovskite ferrielectrics (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro


    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of ‘polarization twist’, which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms. PMID:27586824

  17. Polarization twist in perovskite ferrielectrics (United States)

    Kitanaka, Yuuki; Hirano, Kiyotaka; Ogino, Motohiro; Noguchi, Yuji; Miyayama, Masaru; Moriyoshi, Chikako; Kuroiwa, Yoshihiro


    Because the functions of polar materials are governed primarily by their polarization response to external stimuli, the majority of studies have focused on controlling polar lattice distortions. In some perovskite oxides, polar distortions coexist with nonpolar tilts and rotations of oxygen octahedra. The interplay between nonpolar and polar instabilities appears to play a crucial role, raising the question of how to design materials by exploiting their coupling. Here, we introduce the concept of ‘polarization twist’, which offers enhanced control over piezoelectric responses in polar materials. Our experimental and theoretical studies provide direct evidence that a ferrielectric perovskite exhibits a large piezoelectric response because of extended polar distortion, accompanied by nonpolar octahedral rotations, as if twisted polarization relaxes under electric fields. The concept underlying the polarization twist opens new possibilities for developing alternative materials in bulk and thin-film forms.

  18. Polar low monitoring (United States)

    Bobylev, Leonid; Zabolotskikh, Elizaveta; Mitnik, Leonid


    Polar lows are intense mesoscale atmospheric low pressure weather systems, developing poleward of the main baroclinic zone and associated with high surface wind speeds. Small size and short lifetime, sparse in-situ observations in the regions of their development complicate polar low study. Our knowledge of polar lows and mesocyclones has come almost entirely during the period of satellite remote sensing since, by virtue of their small horizontal scale, it was rarely possible to analyse these lows on conventional weather charts using only the data from the synoptic observing network. However, the effects of intense polar lows have been felt by coastal communities and seafarers since the earliest times. These weather systems are thought to be responsible for the loss of many small vessels over the centuries, although the nature of the storms was not understood and their arrival could not be predicted. The actuality of the polar low research is stipulated by their high destructive power: they are a threat to such businesses as oil and gas exploration, fisheries and shipping. They could worsen because of global warming: a shrinking of sea ice around the North Pole, which thawed to its record minimum in the summer of 2007, is likely to give rise to more powerful storms that form only over open water and can cause hurricane-strength winds. Therefore, study of polar lows, their timely detection, tracking and forecasting represents a challenge for today meteorology. Satellite passive microwave data, starting from Special Sensor Microwave Imager (SSM/I) onboard Defense Meteorological Satellite Program (DMSP) satellite, remain invaluable source of regularly available remotely sensed data to study polar lows. The sounding in this spectral range has several advantages in comparison with observations in visible and infrared ranges and Synthetic Aperture Radar (SAR) data: independence on day time and clouds, regularity and high temporal resolution in Polar Regions. Satellite

  19. Polarization swings in blazars (United States)

    Lyutikov, Maxim; Kravchenko, Evgeniya V.


    We present a model of blazar variability that can both reproduce smooth large polarization angle swings and at the same time allow for the seemingly random behaviour of synchrotron fluxes, polarization fraction and, occasionally, π/2 polarization jumps. We associate the blazar flaring activity with a jet carrying helical magnetic fields and propagating along a variable direction (and possibly with a changing bulk Lorentz factor). The model predicts that for various jet trajectories (i) electric vector position angle (EVPA) can experience large smooth temporal variations, while at the same time polarization fraction (Π) can be highly variable; (ii) Π ∼ 0 near sudden EVPA jumps of 90°, but can also remain constant for large, smoother EVPA swings; (iii) the total angle of EVPA rotation can be arbitrarily large; and (iv) intensity I is usually maximal at points of fastest EVPA changes, but can have a minimum. Thus, even for a regular, deterministic motion of a steadily emitting jet, the observed properties can vary in a non-monotonic and/or seemingly stochastic way. Intrinsic fluctuations of the emissivity will further complicate the intensity profiles, but are expected to preserve the polarization structure.

  20. The METOP-A Orbit Acquisition Strategy and its LEOP Operational Experience (United States)

    Merz, K.; Serrano, M. A. Martin; Kuijper, D.; Matatoros, M. A. Garcia


    Europe's first polar-orbiting weather satellite, METOPA, was launched by a Soyuz launcher from Baikonur Cosmodrome on the 19th of October of 2006. The routine operations of METOP-A are conducted by EUMETSAT (European Organization for Exploitation of Meteorological Satellites) in the frame of the European Polar System mission (EPS). The METOP-A Launch and Early Orbit Phase (LEOP) operations have been performed by ESA/ESOC. The Flight Dynamics Orbit Determination and Control team (OD&C) at ESOC was in charge of correcting the S/C orbit as delivered by the launcher in such a way that EUMETSAT would be able to acquire the reference orbit with a drift-stop manoeuvre approximately two weeks after a LEOP of 3 days and Hand-Over to the EUMETSAT Control Centre (EUMETSAT-CC) in Darmstadt, Germany. The various strict constraints and the short amount of time available for ESOC operations made this task challenging. Several strategies were prepared before launch and analysed during LEOP based on the achieved injection orbit. This paper presents the different manoeuvre strategies investigated and finally applied to acquire the operational orbit, reporting as well the details of its execution and final achieved state.

  1. Numerical Solution of the Evolution Equation for Orbital Angular Momentum of Partons in the Nucleon

    CERN Document Server

    Martin, O; Schäfer, A


    The evolution of orbital angular momentum distributions within the radiative parton model is studied. We use different scenarios for the helicity weighted parton distributions and consider a broad range of input distributions for orbital angular momentum. In all cases we are lead to the conclusion that the absolute value of the average angular momentum per parton peaks at relatively large $x\\approx 0.1$ for perturbatively accessible scales. Furthermore, in all scenarios considered here the average orbital angular momentum per parton is several times larger for gluons than for quarks which favours gluon initiated reactions to measure orbital angular momentum. The large gluon polarization typically obtained in NLO-fits to DIS data is primarily canceled by the gluon orbital angular momentum.

  2. Orbits of the visual binaries ADS 8814 and ADS 8065 from observations along a short arc (United States)

    Kiselev, A. A.; Kiyaeva, O. V.; Romanenko, L. G.; Gorynya, N. A.


    The orbits of the visual binaries ADS 8814 and ADS 8065 are determined for the first time. The orbits were calculated using the parameters of the apparent motion, based on position observations along short arcs obtained on the 26-inch refrector of the Pulkovo Observatory, supplemented with radial-velocity observations for the stellar components in both pairs obtained on the 1-m telescope of the Simeiz Section of the Crimean Astrophysical Observatory. All previous visual and photographic observations of these stars after 1832 were also taken into account. The orbit of ADS 8814 was refined using the differential-correction method. The orbital periods of these two stars are about 800 and 6000 years, respectively. The mass estimates derived for the known parallaxes from the Hipparcos catalog correspond to the spectral types of these stars. The polar vectors of the obtained orbits in Galactic coordinates are also given.

  3. The orbit structure of the Gelfand-Zeitlin group on n x n matrices

    CERN Document Server

    Colarusso, Mark


    In recent work ([KW1],[KW2]), Kostant and Wallach construct an action of a simply connected Lie group $A$ isomorphic to \\mathbb{C}^{{n\\choose 2}} on gl(n) using a completely integrable system derived from the Poisson analogue of the Gelfand-Zeitlin subalgebra of the enveloping algebra. In [KW1], the authors show that $A$-orbits of dimension {n\\choose 2} form Lagrangian submanifolds of regular adjoint orbits in gl(n). They describe the orbit structure of $A$ on a certain Zariski open subset of regular semisimple elements. In this paper, we describe all $A$-orbits of dimension {n\\choose 2} and thus all polarizations of regular adjoint orbits obtained using Gelfand-Zeitlin theory.

  4. The Submillimeter Polarization of Sgr A*

    CERN Document Server

    Marrone, D P; Zhao, J H; Rao, R; Marrone, Daniel P.; Moran, James M.; Zhao, Jun-Hui; Rao, Ramprasad


    We report on the submillimeter properties of Sagittarius A* derived from observations with the Submillimeter Array and its polarimeter. We find that the spectrum of Sgr A* between 230 and 690 GHz is slightly decreasing when measured simultaneously, indicating a transition to optically thin emission around 300-400 GHz. We also present very sensitive and well calibrated measurements of the polarization of Sgr A* at 230 and 345 GHz. With these data we are able to show for the first time that the polarization of Sgr A* varies on hour timescales, as has been observed for the total intensity. On one night we find variability that may arise from a polarized "blob" orbiting the black hole. Finally, we use the ensemble of observations to determine the rotation measure. This represents the first statistically significant rotation measure determination and the only one made without resorting to comparing position angles measured at separate epochs. We find a rotation measure of (-5.6+/-0.7)x10^5 rad/m^2, with no evidenc...

  5. On polarization in biomembranes

    DEFF Research Database (Denmark)

    Zecchi, Karis Amata

    close to physiological conditions, making these effects biologically relevant. In this work, we consider the case of asymmetric membranes which can display spontaneous polarization in the absence of a field. Close to the phase transition, we find that the membrane displays piezoelectric, flexoelectric...... and thermoelectric behaviour. In particular, the membrane capacitance is a nonlinear function of the applied voltage. Furthermore, in the presence of spontaneous polarization, our thermodynamical description is able to explain the outward rectified current-voltage relationship measured on synthetic lipid bilayers....... Due to the nonlinear dependence of the membrane capacitance and conductance on voltage and the presence of spontaneous polarization, the traditional equivalent circuit of the membrane is not an accurate description in physiological conditions. An updated equivalent circuit of the lipid bilayer is here...

  6. A lunar polar expedition (United States)

    Dowling, Richard; Staehle, Robert L.; Svitek, Tomas


    Advanced exploration and development in harsh environments require mastery of basic human survival skill. Expeditions into the lethal climates of Earth's polar regions offer useful lessons for tommorrow's lunar pioneers. In Arctic and Antarctic exploration, 'wintering over' was a crucial milestone. The ability to establish a supply base and survive months of polar cold and darkness made extensive travel and exploration possible. Because of the possibility of near-constant solar illumination, the lunar polar regions, unlike Earth's may offer the most hospitable site for habitation. The World Space Foundation is examining a scenario for establishing a five-person expeditionary team on the lunar north pole for one year. This paper is a status report on a point design addressing site selection, transportation, power, and life support requirements.

  7. Polarized Light from Jupiter (United States)


    These images taken through the wide angle camera near closest approach in the deep near-infrared methane band, combined with filters which sense electromagnetic radiation of orthogonal polarization, show that the light from the poles is polarized. That is, the poles appear bright in one image, and dark in the other. Polarized light is most readily scattered by aerosols. These images indicate that the aerosol particles at Jupiter's poles are small and likely consist of aggregates of even smaller particles, whereas the particles at the equator and covering the Great Red Spot are larger. Images like these will allow scientists to ascertain the distribution, size and shape of aerosols, and consequently, the distribution of heat, in Jupiter's atmosphere.

  8. No More Polarization, Please!

    DEFF Research Database (Denmark)

    Hansen, Mia Reinholt

    The organizational science literature on motivation has for long been polarized into two main positions; the organizational economic position focusing on extrinsic motivation and the organizational behavior position emphasizing intrinsic motivation. With the rise of the knowledge economy...... and the increasing levels of complexities it entails, such polarization is not fruitful in the attempt to explain motivation of organizational members. This paper claims that a more nuanced perspective on motivation, acknowledging the co-existence of intrinsic and extrinsic motivation, the possible interaction...... between the two as well as different types of motivations filling in the gap between the two polar types, is urgently needed in the organizational science literature. By drawing on the research on intrinsic and extrinsic motivation conducted in social psychology and combining this with contributions from...

  9. [Polar body diagnosis]. (United States)

    Montag, M; van der Ven, K; van der Ven, H


    Polar body diagnosis (PBD) is a diagnostic method for the indirect genetic analysis of oocytes. Polar bodies are by-products of the meiotic cell cycle which have no influence on further embryo development. The biopsy of polar bodies can be accomplished either by zona drilling or laser drilling within a very short time period. The paternal contribution to the genetic constitution of the developing embryo cannot be diagnosed by PBD. The major application of PBD is the detection of maternally derived chromosomal aneuploidies and translocations in oocytes. For these indications, PBD may offer a viable alternative to blastomere biopsy as the embryo's integrity remains unaffected in contrast to preimplantation genetic diagnosis by blastomere biopsy. The fast development in the field of molecular diagnostics will also influence PBD and probably allow a more general diagnosis in the future.

  10. SPHERES Mars Orbiting Sample Return External Orbiting Capture Project (United States)

    National Aeronautics and Space Administration — NASA's Mars Sample Return (MSR) mission scenario utilizes a small Orbiting Sample (OS) satellite, launched from the surface of Mars, which will rendezvous with an...

  11. Orbital Infarction due to Sickle Cell Disease without Orbital Pain

    Directory of Open Access Journals (Sweden)

    Cameron L. McBride


    Full Text Available Sickle cell disease is a hemoglobinopathy that results in paroxysmal arteriolar occlusion and tissue infarction that can manifest in a plurality of tissues. Rarely, these infarcted crises manifest in the bony orbit. Orbital infarction usually presents with acute onset of periorbital tenderness, swelling, erythema, and pain. Soft tissue swelling can result in proptosis and attenuation of extraocular movements. Expedient diagnosis of sickle cell orbital infarction is crucial because this is a potentially sight-threatening entity. Diagnosis can be delayed since the presentation has physical and radiographic findings mimicking various infectious and traumatic processes. We describe a patient who presented with sickle cell orbital crisis without pain. This case highlights the importance of maintaining a high index of suspicion in patients with known sickle cell disease or of African descent born outside the United States in a region where screening for hemoglobinopathy is not routine, even when the presentation is not classic.

  12. [Orbital tumor emergencies in childhood]. (United States)

    Morax, S; Desjardins, L


    Emergencies in childhood orbital tumorals are rare. The absolute emergency involves malignant primary orbital tumors, such as rhabdomyosarcoma or secondary malignant tumors (metastatic neuroblastoma, leukemia), involving a vital prognosis requiring prompt diagnosis. Delayed emergencies are usually vascular lesions. Among these lesions, immature orbital hemangioma, with a good prognosis, must be distinguished from orbital adnexal lymphangiomas, which are less frequent but can lead to dramatic cosmetic and functional disorders. In rare cases, they can be responsible for sudden, painful proptosis, due to orbital hemorrhage, with a risk of optic nerve compression, requiring emergency surgical treatment. Neurogenous lesions, either isolated, such as in gliomas, or associated with a systemic disease, such as Recklinghausen neurofibromatosis, threaten the functional prognosis. Diagnosis of pediatric orbital tumors is based on a good clinical examination, precise imaging investigations, and evaluation of the locoregional extension of the tumor. Biopsy is required in emergency situations, when rhabdomyosarcoma is suspected, in order to start the chemotherapy. However, the biopsy can be superfluous, and even useless or dangerous, when clinical and imaging investigations are sufficient to provide a diagnosis of capillary hemangioma, lymphangioma, or metastatic tumor from an abdominal malignancy. Treatment is closely related to the etiopathogenesis of the tumor. The outcomes are vital, functional and cosmetic. They may require orbital surgery (biopsy, tumoral resection, orbital decompression in case of a compressive hemorrhage), systemic corticotherapy (as in immature adnexal hemangioma), radiation, and chemotherapy (rhabdomyosarcoma, secondary malignant tumor). These diseases require a pediatric ophthalmological medical center specializing in orbital surgery, with close collaboration of multiple specialists such as onco-pediatricians and neurosurgeons.

  13. Inertial effect on spin-orbit coupling and spin transport (United States)

    Basu, B.; Chowdhury, Debashree


    We theoretically study the renormalization of inertial effects on the spin dependent transport of conduction electrons in a semiconductor by taking into account the interband mixing on the basis of k→ṡp→ perturbation theory. In our analysis, for the generation of spin current we have used the extended Drude model where the spin-orbit coupling plays an important role. We predict enhancement of the spin current resulting from the renormalized spin-orbit coupling effective in our model in cubic and non-cubic crystals. Attention has been paid to clarify the importance of gauge fields in the spin transport of this inertial system. A theoretical proposition of a perfect spin filter has been done through the Aharonov-Casher like phase corresponding to this inertial system. For a time dependent acceleration, effect of k→ ṡp→ perturbation on the spin current and spin polarization has also been addressed. Furthermore, achievement of a tunable source of polarized spin current through the non uniformity of the inertial spin-orbit coupling strength has also been discussed.

  14. Ocular complications of orbital venography. (United States)

    Safer, J N; Guibor, P


    Three ocular complications directly related to orbital venography are described, one resulting in permanent loss of vision,. The patient had lymphangioma of the orbit which evidently had bled secondary to increased venous pressure and injection of contrast bolus. Both of the 2 patients with transient visual disturbances had diabetic retinopathy. The common factor is felt to be an imparied vascular bed which cannot meet the stress of increased venous pressure and contrast medium injection. Conditions which predispose to ocular-orbital stasis and/or hemorrhage are discussed.

  15. Surface properties of Mars' polar layered deposits and polar landing sites (United States)

    Vasavada, Ashwin R.; Williams, Jean-Pierre; Paige, David A.; Herkenhoff, Ken E.; Bridges, Nathan T.; Greeley, Ronald; Murray, Bruce C.; Bass, Deborah S.; McBride, Karen S.


    On December 3, 1999, the Mars Polar Lander and Mars Microprobes will land on the planet's south polar layered deposits near (76°S, 195°W) and conduct the first in situ studies of the planet's polar regions. The scientific goals of these missions address several poorly understood and globally significant issues, such as polar meteorology, the composition and volatile content of the layered deposits, the erosional state and mass balance of their surface, their possible relationship to climate cycles, and the nature of bright and dark aeolian material. Derived thermal inertias of the southern layered deposits are very low (50-100 Jm-2s-1/2K-1), suggesting that the surface down to a depth of a few centimeters is generally fine grained or porous and free of an appreciable amount of rock or ice. The landing site region is smoother than typical cratered terrain on ~1 kmpixel-1 Viking Orbiter images but contains low-relief texture on ~5 to 100 mpixel-1 Mariner 9 and Mars Global Surveyor images. The surface of the southern deposits is older than that of the northern deposits and appears to be modified by aeolian erosion or ablation of ground ice.

  16. Microwave Frequency Polarizers (United States)

    Ha, Vien The; Mirel, Paul; Kogut, Alan J.


    This article describes the fabrication and analysis of microwave frequency polarizing grids. The grids are designed to measure polarization from the cosmic microwave background. It is effective in the range of 500 to 1500 micron wavelength. It is cryogenic compatible and highly robust to high load impacts. Each grid is fabricated using an array of different assembly processes which vary in the types of tension mechanisms to the shape and size of the grids. We provide a comprehensive study on the analysis of the grids' wire heights, diameters, and spacing.

  17. Internal polarized targets

    Energy Technology Data Exchange (ETDEWEB)

    Kinney, E.R.; Coulter, K.; Gilman, R.; Holt, R.J.; Kowalczyk, R.S.; Napolitano, J.; Potterveld, D.H.; Young, L. (Argonne National Lab., IL (USA)); Mishnev, S.I.; Nikolenko, D.M.; Popov, S.G.; Rachek, I.A.; Temnykh, A.B.; Toporkov, D.K.; Tsentalovich, E.P.; Wojtsekhowski, B.B. (AN SSSR, Novosibirsk (USSR). Inst. Yadernoj Fiziki)


    Internal polarized targets offer a number of advantages over external targets. After a brief review of the basic motivation and principles behind internal polarized targets, the technical aspects of the atomic storage cell will be discussed in particular. Sources of depolarization and the means by which their effects can be ameliorated will be described, especially depolarization by the intense magnetic fields arising from the circulating particle beam. The experience of the Argonne Novosibirsk collaboration with the use of a storage cell in a 2 GeV electron storage ring will be the focus of this technical discussion. 17 refs., 11 figs.

  18. New compact neutron polarizer (United States)

    Krist, Th; Kennedy, S. J.; Hicks, T. J.; Mezei, F.

    A new type of a neutron polarizing bender was developed in co-operation with BENSC and ANSTO. It is based upon bent thin silicon wafers coated on one side with SiFeCo polarizing supermirrors and on the other side with Gd. Initial tests at BENSC in a 300 Oe magnetic field yielded a transmission of spin-up neutrons of about 55% over an angle range of 0.75° and flipping ratios > 30. Subsequent tests at ANSTO at 1200 Oe yielded a transmission of 48% with a flipping ratio > 45.

  19. Deriving polarization properties of desert-reflected solar spectra with PARASOL data (United States)

    Sun, W.; Baize, R. R.; Lukashin, C.; Hu, Y.


    One of the major objectives of the Climate Absolute Radiance and Refractivity Observatory (CLARREO) is to conduct highly accurate spectral observations to provide an on-orbit inter-calibration standard for relevant Earth-observing sensors with various channels. To calibrate an Earth-observing sensor's measurements with the highly accurate data from the CLARREO, errors in the measurements caused by the sensor's sensitivity to the polarization state of light must be corrected. For correction of the measurement errors due to the light's polarization, both the instrument's dependence on the incident polarization state and the on-orbit knowledge of the polarization state of light as a function of observed scene type, viewing geometry, and solar wavelength are required. In this study, an algorithm for deriving the spectral polarization state of solar light from the desert is reported. The desert/bare land surface is assumed to be composed of two types of areas: fine sand grains with diffuse reflection (Lambertian non-polarizer) and quartz-rich sand particles with facets of various orientations (specular-reflection polarizer). The Adding-Doubling Radiative Transfer Model (ADRTM) is applied to integrate the atmospheric absorption and scattering in the system. Empirical models are adopted in obtaining the diffuse spectral reflectance of sands and the optical depth of the dust aerosols over the desert. The ratio of non-polarizer area to polarizer area and the angular distribution of the facet orientations are determined by fitting the modeled polarization states of light to the measurements at three polarized channels (490, 670, and 865 nm) by the Polarization and Anisotropy of Reflectances for Atmospheric Science instrument coupled with Observations from a Lidar (PARASOL). Based on this physical model of the surface, the desert-reflected solar light's polarization state at any wavelength in the whole solar spectra can be calculated with the ADRTM.


    Institute of Scientific and Technical Information of China (English)



    The homoclinic bifurcations in four dimensional vector fields are investigated by setting up a local coordinates near the homoclinic orbit. This homoclinic orbit is nonprincipal in the meanings that its positive semi-orbit takes orbit flip and its unstable foliation takes inclination flip. The existence, nonexistence, uniqueness and coexistence of the 1-homoclinic orbit and the 1-periodic orbit are studied. The existence of the twofold periodic orbit and three-fold periodic orbit are also obtained.

  1. The physics of polarization (United States)

    Landi Degl'Innocenti, Egidio

    This course is intended to give a description of the basic physical concepts which underlie the study and the interpretation of polarization phenomena. Apart from a brief historical introduction (Sect. 1), the course is organized in three parts. A first part (Sects. 2 - 6) covers the most relevant facts about the polarization phenomena that are typically encountered in laboratory applications and in everyday life. In Sect. 2, the modern description of polarization in terms of the Stokes parameters is recalled, whereas Sect. 3 is devoted to introduce the basic tools of laboratory polarimetry, such as the Jones calculus and the Mueller matrices. The polarization phenomena which are met in the reflection and refraction of a beam of radiation at the separation surface between two dielectrics, or between a dielectric and a metal, are recalled in Sect. 4. Finally, Sect. 5 gives an introduction to the phenomena of dichroism and of anomalous dispersion and Sect. 6 summarizes the polarization phenomena that are commonly encountered in everyday life. The second part of this course (Sects. 7-14) deals with the description, within the formalism of classical physics, of the spectro-polarimetric properties of the radiation emitted by accelerated charges. Such properties are derived by taking as starting point the Liénard and Wiechert equations that are recalled and discussed in Sect. 7 both in the general case and in the non-relativistic approximation. The results are developed to find the percentage polarization, the radiation diagram, the cross-section and the spectral characteristics of the radiation emitted in different phenomena particularly relevant from the astrophysical point of view. The emission of a linear antenna is derived in Sect. 8. The other Sections are devoted to Thomson scattering (Sect. 9), Rayleigh scattering (Sect. 10), Mie scattering (Sect. 11), bremsstrahlung radiation (Sect. 12), cyclotron radiation (Sect. 13), and synchrotron radiation (Sect. 14

  2. Quantifying the importance of orbital over spin correlations in delta-Pu within density-functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Soderlind, P; Wolfer, W


    Spin and orbital and electron correlations are known to be important when treating the high-temperature {delta} phase of plutonium within the framework of density-functional theory (DFT). One of the more successful attempts to model {delta}-Pu within this approach has included condensed-matter generalizations of Hund's three rules for atoms, i.e., spin polarization, orbital polarization, and spin-orbit coupling. Here they perform a quantitative analysis of these interactions relative rank for the bonding and electronic structure in {delta}-Pu within the DFT model. The result is somewhat surprising in that spin-orbit coupling and orbital polarization are far more important than spin polarization for a realistic description of {delta}-Pu. They show that these orbital correlations on their own, without any formation of magnetic spin moments, can account for the low atomic density of the {delta} phase with a reasonable equation-of-state. In addition, this unambiguously non-magnetic (NM) treatment produces a one-electron spectra with resonances close to the Fermi level consistent with experimental valence band photoemission spectra.

  3. Polarized Proton Collisions at RHIC

    CERN Document Server

    Bai, Mei; Alekseev, Igor G; Alessi, James; Beebe-Wang, Joanne; Blaskiewicz, Michael; Bravar, Alessandro; Brennan, Joseph M; Bruno, Donald; Bunce, Gerry; Butler, John J; Cameron, Peter; Connolly, Roger; De Long, Joseph; Drees, Angelika; Fischer, Wolfram; Ganetis, George; Gardner, Chris J; Glenn, Joseph; Hayes, Thomas; Hseuh Hsiao Chaun; Huang, Haixin; Ingrassia, Peter; Iriso, Ubaldo; Laster, Jonathan S; Lee, Roger C; Luccio, Alfredo U; Luo, Yun; MacKay, William W; Makdisi, Yousef; Marr, Gregory J; Marusic, Al; McIntyre, Gary; Michnoff, Robert; Montag, Christoph; Morris, John; Nicoletti, Tony; Oddo, Peter; Oerter, Brian; Osamu, Jinnouchi; Pilat, Fulvia Caterina; Ptitsyn, Vadim; Roser, Thomas; Satogata, Todd; Smith, Kevin T; Svirida, Dima; Tepikian, Steven; Tomas, Rogelio; Trbojevic, Dejan; Tsoupas, Nicholaos; Tuozzolo, Joseph; Vetter, Kurt; Wilinski, Michelle; Zaltsman, Alex; Zelenski, Anatoli; Zeno, Keith; Zhang, S Y


    The Relativistic Heavy Ion Collider~(RHIC) provides not only collisions of ions but also collisions of polarized protons. In a circular accelerator, the polarization of polarized proton beam can be partially or fully lost when a spin depolarizing resonance is encountered. To preserve the beam polarization during acceleration, two full Siberian snakes were employed in RHIC to avoid depolarizing resonances. In 2003, polarized proton beams were accelerated to 100~GeV and collided in RHIC. Beams were brought into collisions with longitudinal polarization at the experiments STAR and PHENIX by using spin rotators. RHIC polarized proton run experience demonstrates that optimizing polarization transmission efficiency and improving luminosity performance are significant challenges. Currently, the luminosity lifetime in RHIC is limited by the beam-beam effect. The current state of RHIC polarized proton program, including its dedicated physics run in 2005 and efforts to optimize luminosity production in beam-beam limite...

  4. Spin Filtering in a Nanowire Superlattice by Dresselhause Spin-Orbit Coupling

    Institute of Scientific and Technical Information of China (English)

    Samad Javidan


    @@ An InAs/GaSb nanowire Superlattice using GaAs for the impure layers is proposed.Dresselhaus spin-orbit coupling eliminates spin degeneracy, induces one miniband in the superlattices to split into two minibands and leads to complete spin polarization and excellent filtering by optimizing the well and barrier widths and GaAs layer distances.

  5. Real and Hybrid Atomic Orbitals. (United States)

    Cook, D. B.; Fowler, P. W.


    Demonstrates that the Schrodinger equation for the hydrogenlike atom separates in both spheroconal and prolate spheroidal coordinates and that these separations provide a sound theoretical basis for the real and hybrid atomic orbitals. (Author/SK)

  6. [Orbital metastasis in malignant melanoma]. (United States)

    Pedroli, G L; Hamedani, M; Barraco, P; Oubaaz, A; Morax, S


    We report the case of a 60-year-old man presenting bilateral progressive proptosis with diplopia, weight loss, tachycardia, nervosity, and stomach pain. These signs seemed at first to favor a diagnosis of Graves'ophthalmopathy. Thyroid tests were negative and the initial orbital CT scan was considered normal. A new radiological investigation 4 months later in our hospital revealed typical hypertrophy of the extraocular muscles compatible with orbital metastasis. The systemic investigations demonstrated a pulmonary tumor, multiple hepatic lesions, and several pigmented nodules of gastric mucosa. The pathology of pulmonary and gastric specimens confirmed the diagnosis of malignant melanoma. The primary lesion remains unknown. The authors discuss the differential diagnoses of orbital metastasis and the radiological characteristics of orbital metastasis in malignant melanoma.

  7. NASA Orbital Debris Baseline Populations (United States)

    Krisko, Paula H.; Vavrin, A. B.


    The NASA Orbital Debris Program Office has created high fidelity populations of the debris environment. The populations include objects of 1 cm and larger in Low Earth Orbit through Geosynchronous Transfer Orbit. They were designed for the purpose of assisting debris researchers and sensor developers in planning and testing. This environment is derived directly from the newest ORDEM model populations which include a background derived from LEGEND, as well as specific events such as the Chinese ASAT test, the Iridium 33/Cosmos 2251 accidental collision, the RORSAT sodium-potassium droplet releases, and other miscellaneous events. It is the most realistic ODPO debris population to date. In this paper we present the populations in chart form. We describe derivations of the background population and the specific populations added on. We validate our 1 cm and larger Low Earth Orbit population against SSN, Haystack, and HAX radar measurements.

  8. Quark spin-orbit correlations

    CERN Document Server

    Lorcé, Cédric


    The proton spin puzzle issue focused the attention on the parton spin and orbital angular momentum contributions to the proton spin. However, a complete characterization of the proton spin structure requires also the knowledge of the parton spin-orbit correlation. We showed that this quantity can be expressed in terms of moments of measurable parton distributions. Using the available phenomenological information about the valence quarks, we concluded that this correlation is negative, meaning that the valence quark spin and kinetic orbital angular momentum are, in average, opposite. The quark spin-orbit correlation can also be expressed more intuitively in terms of relativistic phase-space distributions, which can be seen as the mother distributions of the standard generalized and transverse-momentum dependent parton distributions. We present here for the first time some examples of the general multipole decomposition of these phase-space distributions.


    Directory of Open Access Journals (Sweden)



    Full Text Available AIM : To study the orbital manifestations in patients with sinus disease. METHODS : Patients wit h paranasal sinus disease presenting to OPD at Government ENT Hospital, AMC, Visakhapatnam from January 2012 to June 2014 were screened for orbital manifestations. Out of these, thirteen patients with orbital disease were referred to GREH, AMC, Visakhapatn am and were thoroughly investigated and managed appropriately. RESULTS : Out of the 14 patients 4 were female and 10 were male. Age ranged from 19 years to 70 years. 5 had maxillary sinus disease (4 - carcinoma and 1 case of mucormycosis. Frontal sinus dis ease was seen in two patients, one fibrous dysplasia and one malignancy. Five patients had ethmoidal sinus disease of which three patients were found to have ethmoidal sinus tumour (Malignant melanoma, Squamous cell Carcinoma. More than two sinuses were i nvolved in 2 patients. CONCLUSIONS : Early screening of patients with sinus disease by an Ophthalmologist can help in preventing severe vision threatening orbital complications.

  10. Closed Orbits in Phase Space (United States)

    Murphy, Andrew; Haestad, Jace; Morgan, Thomas


    We report characteristics of closed classical orbits in an electric field in phase space produced in photoabsorption. Rydberg states of atomic and molecular hydrogen and helium are considered. The core potential used for the hydrogen molecule is an effective one electron one center core potential evaluated at the internuclear equilibrium distance. Poincare surfaces of section in phase space are generated by integrating the equations of motion in semiparabolic coordinates u = (r + z) 1 / 2 and v = (r - z) 1 / 2, and plotting the location in phase space (pv versus v) whenever u = 0, with the electric field in the z direction. Combination orbits produced by Rydberg electron core scattering are studied and the evolution in phase space of these combination orbits due to scattering from one closed orbit into another is investigated. Connections are made to measured laser photoabsorption experiments that excite Rydberg states (20 recurrence spectra. The phase space structures responsible for the spectra are identified.

  11. A Case of Orbital Histoplasmosis. (United States)

    Krakauer, Mark; Prendes, Mark Armando; Wilkes, Byron; Lee, Hui Bae Harold; Fraig, Mostafa; Nunery, William R


    Histoplasma capsulatum var capsulatum is a dimorphic fungus endemic to the Ohio and Mississippi River Valleys of the United States. In this case report, a 33-year-old woman who presented with a right orbital mass causing progressive vision loss, diplopia, and facial swelling is described. Lateral orbitotomy with lateral orbital wall bone flap was performed for excisional biopsy of the lesion. The 1.5 × 1.8 × 2.3 cm cicatricial mass demonstrated a granulomatous lesion with necrosis and positive staining consistent with Histoplasma capsulatum var capsulatum infection. To the authors' knowledge, this is the first case of orbital histoplasmosis to be reported in the United States and the first case worldwide of orbital histoplasmosis due to Histoplasma capsulatum var capsulatum.

  12. Formation around planetary displaced orbit

    Institute of Scientific and Technical Information of China (English)

    GONG Sheng-ping; LI Jun-feng; BAOYIN He-xi


    The paper investigates the relative motion around the planetary displaced orbit. Several kinds of displaced orbits for geocentric and martian cases were discussed. First, the relative motion was linearized around the displaced orbits. Then, two seminatural control laws were investigated for each kind of orbit and the stable regions were obtained for each case. One of the two control laws is the passive control law that is very attractive for engineering practice. However, the two control laws are not very suitable for the Martian mission. Another special semi-natural control law is designed based on the requirement of the Martian mission. The results show that large stable regions exist for the control law.

  13. Orbital entanglement in quantum chemistry

    CERN Document Server

    Boguslawski, Katharina


    The basic concepts of orbital entanglement and its application to chemistry are briefly reviewed. The calculation of orbital entanglement measures from correlated wavefunctions is discussed in terms of reduced $n$-particle density matrices. Possible simplifications in their evaluation are highlighted in case of seniority-zero wavefunctions. Specifically, orbital entanglement allows us to dissect electron correlation effects in its strong and weak contributions, to determine bond orders, to assess the quality and stability of active space calculations, to monitor chemical reactions, and to identify points along the reaction coordinate where electronic wavefunctions change drastically. Thus, orbital entanglement represents a useful and intuitive tool to interpret complex electronic wavefunctions and to facilitate a qualitative understanding of electronic structure and how it changes in chemical processes.

  14. How to Orbit the Earth. (United States)

    Quimby, Donald J.


    Discusses the geometry, algebra, and logic involved in the solution of a "Mindbenders" problem in "Discover" magazine and applies it to calculations of satellite orbital velocity. Extends the solution of this probe to other applications of falling objects. (JM)

  15. Orbital mechanics near Lagrange's points


    Utashima, Masayoshi; 歌島 昌由


    The first libration-point satellite ISEE-3 (International Sun-Earth Explorer-3) was launched in 1978. Though, no libration-point satellites were realized after the launch of the ISEE-3, NASA launched the ESA's Solar and Heliospheric Observatory (SOHO) spacecraft into the halo orbit in the sun-earth system in late 1995. The halo orbit in the sun-earth system is adequate for missions such as solar observation, astronomical observation, NEO (Near Earth Objects) observation, communications with t...

  16. Orbit Determination Analysis for SSAPurposes



    Space Situational Awareness (SSA) is the characterization of the space environmentand of space activities. The fundament of SSA is the access to information about theorbit of space objects. There exist several techniques to determine the orbit of objects inspace, both from space-based and from ground-based observations. This Master's Thesisproject aims at investigating orbit determinations from ground-based radar observations.In particular, the use of the EISCAT Ultra-High-Frequency (UHF) inc...

  17. Orbits in a logarithmic potential

    Energy Technology Data Exchange (ETDEWEB)

    Hooverman, R. H.


    The characteristics of charged particle orbits in the logarithmic electrostatic potential field surrounding a straight conducting wire at a fixed potential are investigated. The equations of motion of an electron in a logarithmic potential are derived, the limiting cases are considered, and the results of numerical integration of the equations of motion are presented along with sketches of a few representative orbits. (C.E.S.)

  18. Variable polarity arc welding (United States)

    Bayless, E. O., Jr.


    Technological advances generate within themselves dissatisfactions that lead to further advances in a process. A series of advances in welding technology which culminated in the Variable Polarity Plasma Arc (VPPA) Welding Process and an advance instituted to overcome the latest dissatisfactions with the process: automated VPPA welding are described briefly.

  19. Titan Polar Landscape Evolution (United States)

    Moore, Jeffrey M.


    With the ongoing Cassini-era observations and studies of Titan it is clear that the intensity and distribution of surface processes (particularly fluvial erosion by methane and Aeolian transport) has changed through time. Currently however, alternate hypotheses substantially differ among specific scenarios with respect to the effects of atmospheric evolution, seasonal changes, and endogenic processes. We have studied the evolution of Titan's polar region through a combination of analysis of imaging, elevation data, and geomorphic mapping, spatially explicit simulations of landform evolution, and quantitative comparison of the simulated landscapes with corresponding Titan morphology. We have quantitatively evaluated alternate scenarios for the landform evolution of Titan's polar terrain. The investigations have been guided by recent geomorphic mapping and topographic characterization of the polar regions that are used to frame hypotheses of process interactions, which have been evaluated using simulation modeling. Topographic information about Titan's polar region is be based on SAR-Topography and altimetry archived on PDS, SAR-based stereo radar-grammetry, radar-sounding lake depth measurements, and superposition relationships between geomorphologic map units, which we will use to create a generalized topographic map.

  20. Polarized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    de Florian, D.; Epele, L.N.; Fanchiotti, H.; Garcia Canal, C.A.; Sassot, R. (Laboratorio de Fisica Teorica, Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67-1900 La Plata (Argentina))


    We analyze spin-dependent parton distributions consistent with the most recent measurements of the spin-dependent deep inelastic scattering structure functions and obtained in the framework of the spin dilution model. Predictions for the doubly polarized proton-proton Drell-Yan asymmetry, for the high [ital p][sub [ital T