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Sample records for proper motion magnetic

  1. ESO 439-162/163 - a common proper motion binary formed by a magnetic DQ and a DC type white dwarf

    International Nuclear Information System (INIS)

    Ruiz, M.T.; Maza, J.

    1988-01-01

    In the course of a search for faint large proper motion stars, a common proper motion pair was identified having a mu = 0.38 + or - 0.03 arcsec/yr in the direction theta = 233 deg. The stars are separated by 23 arcsec and have apparent visual magnitudes 18.77 and 19.84, respectively. Spectrophotometry of the stars established that the fainter component is a cold DC white dwarf, while the brighter one is a magnetic white dwarf with strong Swan bands of C2 shifted and broadened by an about 10 to the 8th G magnetic field. 6 references

  2. Magnetic fields and proper motions of sunspots. 1

    International Nuclear Information System (INIS)

    Kalman, B.

    1976-01-01

    Determining relation between magnetic fields and intrinsic motions of the Sun spots is considered. Based on daily maps of the longitudinal H 1 and transverse H 2 constituents of the magnetic field and a series of photographs of the Sun a comparison was made of motion of shadow nuclei and semishadow fibres with the structure of the magnetic field in the Sun spot group from 7 till 14 of June, 1969. It was found that the spots moved both along and across the direction of the transverse magnetic field. During the movement of spots changes in the structure of H 2 occurred which in the most cases corresponded to reorientation of lines of force along the trajectory behind the moving spot. However, in some cases the structure of the transverse field behind the moving spot became close to the perpendicular one to the trajectory of the past spot, although it could be almost parallel to the trajectory in front of the spot. The best coincidence of orientations of the spot trajectories with the H 2 structure was obtained near the zero line of the longitudinal field. The orientation of fibres of semishadows along H 2 was observed when the group was near the central meridian

  3. Proper motions and distances of quasars

    International Nuclear Information System (INIS)

    Varshni, Y.P.

    1982-01-01

    The author's theory that quasars are stars raises the question of their proper motions. From the evidence presented in a previous paper, it is hypothesised that planetary nuclei and quasars are related objects and that their distributions in the galaxy are not very different. Proper motions of 30 quasars, calculated from existing measurements, are discussed. It is shown that three of these, namely PHL 1033, LB 8956 and LB 8991, have proper motions comparable to the largest proper motion known amongst the planetary nuclei. From this it is estimated that these three quasars lie within a few hundred parsecs from the sun. The evidence presented in a previous paper and the present one clearly supports the theory that quasars are stars. The possibility of using the interstellar K and H lines as distance indicators of quasars is discussed and the available evidence summarised. The desirability of determining more accurate values of the proper motions of quasars is emphasised. (Auth.)

  4. Determination of proper motions in the Pleiades cluster

    Science.gov (United States)

    Schilbach, E.

    1991-04-01

    For 458 stars in the Pleiades field from the catalog of Eichhorn et al. (1970) proper motions were derived on Tautenburg and CERGA Schmidt telescope plates measured with the automated measuring machine MAMA in Paris. The catalog positions were considered as first epoch coordinates with an epoch difference of ca. 33 years to the observations. The results show good coincidence of proper motions derived with both Schmidt telescopes within the error bars. Comparison with proper motions determined by Vasilevskis et al. (1979) displays some significant differences but no systematic effects depending on plate coordinates or magnitudes could be found. An accuracy of 0.3 arcsec/100a for one proper motion component was estimated. According to the criterion of common proper motion 34 new cluster members were identified.

  5. Large proper motions in the Orion nebula

    International Nuclear Information System (INIS)

    Cudworth, K.M.; Stone, R.C.

    1977-01-01

    Several nebular features, as well as one faint star, with large proper motions were identified within the Orion nebula. The measured proper motions correspond to tangential velocities of up to approximately 70 km sec -1 . One new probable variable star was also found

  6. Cataclysmic variables in the SUPERBLINK proper motion survey

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Julie N.; Thorstensen, John R. [Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755-3528 (United States); Lépine, Sébastien, E-mail: jns@dartmouth.edu [Department of Physics and Astronomy, Georgia State University, 25 Park Place NE, Atlanta, GA 30303 (United States)

    2014-12-01

    We have discovered a new high proper motion cataclysmic variable (CV) in the SUPERBLINK proper motion survey, which is sensitive to stars with proper motions greater than 40 mas yr{sup −1}. This CV was selected for follow-up observations as part of a larger search for CVs selected based on proper motions and their near-UV−V and V−K{sub s} colors. We present spectroscopic observations from the 2.4 m Hiltner Telescope at MDM Observatory. The new CV's orbital period is near 96 minutes, its spectrum shows the double-peaked Balmer emission lines characteristic of quiescent dwarf novae, and its V magnitude is near 18.2. Additionally, we present a full list of known CVs in the SUPERBLINK catalog.

  7. INTERNAL PROPER MOTIONS IN THE ESKIMO NEBULA

    International Nuclear Information System (INIS)

    García-Díaz, Ma. T.; Gutiérrez, L.; Steffen, W.; López, J. A.; Beckman, J.

    2015-01-01

    We present measurements of internal proper motions at more than 500 positions of NGC 2392, the Eskimo Nebula, based on images acquired with WFPC2 on board the Hubble Space Telescope at two epochs separated by 7.695 yr. Comparisons of the two observations clearly show the expansion of the nebula. We measured the amplitude and direction of the motion of local structures in the nebula by determining their relative shift during that interval. In order to assess the potential uncertainties in the determination of proper motions in this object, in general, the measurements were performed using two different methods, used previously in the literature. We compare the results from the two methods, and to perform the scientific analysis of the results we choose one, the cross-correlation method, because it is more reliable. We go on to perform a ''criss-cross'' mapping analysis on the proper motion vectors, which helps in the interpretation of the velocity pattern. By combining our results of the proper motions with radial velocity measurements obtained from high resolution spectroscopic observations, and employing an existing 3D model, we estimate the distance to the nebula to be 1.3 kpc

  8. INTERNAL PROPER MOTIONS IN THE ESKIMO NEBULA

    Energy Technology Data Exchange (ETDEWEB)

    García-Díaz, Ma. T.; Gutiérrez, L.; Steffen, W.; López, J. A. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Km 103 Carretera Tijuana-Ensenada, 22860 Ensenada, B.C. (Mexico); Beckman, J., E-mail: tere@astro.unam.mx, E-mail: leonel@astro.unam.mx, E-mail: wsteffen@astro.unam.mx, E-mail: jal@astro.unam.mx, E-mail: jeb@iac.es [Instituto de Astrofísica de Canarias, La Laguna, Tenerife (Spain)

    2015-01-10

    We present measurements of internal proper motions at more than 500 positions of NGC 2392, the Eskimo Nebula, based on images acquired with WFPC2 on board the Hubble Space Telescope at two epochs separated by 7.695 yr. Comparisons of the two observations clearly show the expansion of the nebula. We measured the amplitude and direction of the motion of local structures in the nebula by determining their relative shift during that interval. In order to assess the potential uncertainties in the determination of proper motions in this object, in general, the measurements were performed using two different methods, used previously in the literature. We compare the results from the two methods, and to perform the scientific analysis of the results we choose one, the cross-correlation method, because it is more reliable. We go on to perform a ''criss-cross'' mapping analysis on the proper motion vectors, which helps in the interpretation of the velocity pattern. By combining our results of the proper motions with radial velocity measurements obtained from high resolution spectroscopic observations, and employing an existing 3D model, we estimate the distance to the nebula to be 1.3 kpc.

  9. The Southern Proper Motion Program. IV. The SPM4 Catalog

    Science.gov (United States)

    Girard, Terrence M.; van Altena, William F.; Zacharias, Norbert; Vieira, Katherine; Casetti-Dinescu, Dana I.; Castillo, Danilo; Herrera, David; Lee, Young Sun; Beers, Timothy C.; Monet, David G.; López, Carlos E.

    2011-07-01

    We present the fourth installment of the Yale/San Juan Southern Proper Motion Catalog, SPM4. The SPM4 contains absolute proper motions, celestial coordinates, and B, V photometry for over 103 million stars and galaxies between the south celestial pole and -20° declination. The catalog is roughly complete to V = 17.5 and is based on photographic and CCD observations taken with the Yale Southern Observatory's double astrograph at Cesco Observatory in El Leoncito, Argentina. The proper-motion precision, for well-measured stars, is estimated to be 2-3 mas yr-1, depending on the type of second-epoch material. At the bright end, proper motions are on the International Celestial Reference System by way of Hipparcos Catalog stars, while the faint end is anchored to the inertial system using external galaxies. Systematic uncertainties in the absolute proper motions are on the order of 1 mas yr-1.

  10. What can Gaia proper motions tell us about Milky Way dwarf galaxies?

    NARCIS (Netherlands)

    Jin, S.; Helmi, A.; Breddels, M.

    We present a proper-motion study on models of the dwarf spheroidal galaxy Sculptor, based on the predicted proper-motion accuracy of Gaia measurements. Gaia will measure proper motions of several hundreds of stars for a Sculptor-like system. Even with an uncertainty on the proper motion of order 1.5

  11. Secular Extragalactic Parallax and Geometric Distances with Gaia Proper Motions

    Science.gov (United States)

    Paine, Jennie; Darling, Jeremiah K.

    2018-06-01

    The motion of the Solar System with respect to the cosmic microwave background (CMB) rest frame creates a well measured dipole in the CMB, which corresponds to a linear solar velocity of about 78 AU/yr. This motion causes relatively nearby extragalactic objects to appear to move compared to more distant objects, an effect that can be measured in the proper motions of nearby galaxies. An object at 1 Mpc and perpendicular to the CMB apex will exhibit a secular parallax, observed as a proper motion, of 78 µas/yr. The relatively large peculiar motions of galaxies make the detection of secular parallax challenging for individual objects. Instead, a statistical parallax measurement can be made for a sample of objects with proper motions, where the global parallax signal is modeled as an E-mode dipole that diminishes linearly with distance. We present preliminary results of applying this model to a sample of nearby galaxies with Gaia proper motions to detect the statistical secular parallax signal. The statistical measurement can be used to calibrate the canonical cosmological “distance ladder.”

  12. Globular Clusters: Absolute Proper Motions and Galactic Orbits

    Science.gov (United States)

    Chemel, A. A.; Glushkova, E. V.; Dambis, A. K.; Rastorguev, A. S.; Yalyalieva, L. N.; Klinichev, A. D.

    2018-04-01

    We cross-match objects from several different astronomical catalogs to determine the absolute proper motions of stars within the 30-arcmin radius fields of 115 Milky-Way globular clusters with the accuracy of 1-2 mas yr-1. The proper motions are based on positional data recovered from the USNO-B1, 2MASS, URAT1, ALLWISE, UCAC5, and Gaia DR1 surveys with up to ten positions spanning an epoch difference of up to about 65 years, and reduced to Gaia DR1 TGAS frame using UCAC5 as the reference catalog. Cluster members are photometrically identified by selecting horizontal- and red-giant branch stars on color-magnitude diagrams, and the mean absolute proper motions of the clusters with a typical formal error of about 0.4 mas yr-1 are computed by averaging the proper motions of selected members. The inferred absolute proper motions of clusters are combined with available radial-velocity data and heliocentric distance estimates to compute the cluster orbits in terms of the Galactic potential models based on Miyamoto and Nagai disk, Hernquist spheroid, and modified isothermal dark-matter halo (axisymmetric model without a bar) and the same model + rotating Ferre's bar (non-axisymmetric). Five distant clusters have higher-than-escape velocities, most likely due to large errors of computed transversal velocities, whereas the computed orbits of all other clusters remain bound to the Galaxy. Unlike previously published results, we find the bar to affect substantially the orbits of most of the clusters, even those at large Galactocentric distances, bringing appreciable chaotization, especially in the portions of the orbits close to the Galactic center, and stretching out the orbits of some of the thick-disk clusters.

  13. THE PROPER MOTION OF PALOMAR 5

    Energy Technology Data Exchange (ETDEWEB)

    Fritz, T. K.; Kallivayalil, N., E-mail: tkf4w@astro.virginia.edu [Department of Astronomy, University of Virginia, Charlottesville, 3530 McCormick Road, VA 22904-4325 (United States)

    2015-10-01

    Palomar 5 (Pal 5) is a faint halo globular cluster associated with narrow tidal tails. It is a useful system to understand the process of tidal dissolution, as well as to constrain the potential of the Milky Way. A well-determined orbit for Pal 5 would enable detailed study of these open questions. We present here the first CCD-based proper motion measurement of Pal 5 obtained using SDSS as a first epoch and new Large Binocular Telescope/Large Binocular Camera (LBC) images as a second, giving a baseline of 15 years. We perform relative astrometry, using SDSS as a distortion-free reference, and images of the cluster and also of the Pal 5 stream for the derivation of the distortion correction for LBC. The reference frame is made up of background galaxies. We correct for differential chromatic refraction using relations obtained from SDSS colors as well as from flux-calibrated spectra, finding that the correction relations for stars and for galaxies are different. We obtain μ{sub α} = −2.296 ± 0.186 mas yr{sup −1} and μ{sub δ} = −2.257 ± 0.181 mas yr{sup −1} for the proper motion of Pal 5. We use this motion, and the publicly available code galpy, to model the disruption of Pal 5 in different Milky Way models consisting of a bulge, a disk, and a spherical dark matter halo. Our fits to the observed stream properties (streak and radial velocity gradient) result in a preference for a relatively large Pal 5 distance of around 24 kpc. A slightly larger absolute proper motion than what we measure also results in better matches but the best solutions need a change in distance. We find that a spherical Milky Way model, with V{sub 0} = 220 km s{sup −1} and V{sub 20} {sub kpc}, i.e., approximately at the apocenter of Pal 5, of 218 km s{sup −1}, can match the data well, at least for our choice of disk and bulge parametrization.

  14. Proper motion survey for solar nearby stars

    International Nuclear Information System (INIS)

    Goldman, Bertrand

    2001-01-01

    For its microlensing observations EROS 2 built one of the largest CCD mosaic opera ting since 1996. This instrument allowed us to survey a large area of the sky, to look for faint, cool compact objects in the Solar neighborhood that may contribute to the Dark Matter revealed by flat rotation curves of spiral galaxies and the Milky Way. We imaged over 400 square degrees, at least three times over four years, with a single, stable instrument. The aim of this work is the reduction, the analysis and the detection of high proper motion objects that would look like those expected in a dark halo. We selected and analyzed thousands of images taken in two bands, visible and near-infrared, and obtained a catalogue of several thousand stars with proper motion typically higher than 80 milli-arc-seconds per year. None of these candidates displays the expected properties of the halo objects: very high proper motion and faintness. The second part of our work was to put constraints on the contributions of white dwarfs and brown dwarfs ta the halo. To do that, we simulated our data set and estimated our sensitivity to halo objects. We compared our results about moderately high proper motion stars with existing Galactic models, and confirmed the robustness of these models. We deduced a upper limit ta the contribution of M_v = 17.5 white dwarfs to the standard halo of 10% (at the 95% confidence level), or 5% of a 14 Gyr old halo, and to the contribution of brown dwarfs of 7% (95% C.L.). Finally, among our candidates, several interesting objects, that do not belong to the halo but are among the coolest and faintest known, have been discovered. Systematic search for faint, nearby objects thus lead us to study disk L dwarfs, as well as old white dwarfs of the disk. (author) [fr

  15. Proper Motion and Secular Variations of Keplerian Orbital Elements

    Directory of Open Access Journals (Sweden)

    Alexey G. Butkevich

    2018-05-01

    Full Text Available High-precision observations require accurate modeling of secular changes in the orbital elements in order to extrapolate measurements over long time intervals, and to detect deviation from pure Keplerian motion caused, for example, by other bodies or relativistic effects. We consider the evolution of the Keplerian elements resulting from the gradual change of the apparent orbit orientation due to proper motion. We present rigorous formulae for the transformation of the orbit inclination, longitude of the ascending node and argument of the pericenter from one epoch to another, assuming uniform stellar motion and taking radial velocity into account. An approximate treatment, accurate to the second-order terms in time, is also given. The proper motion effects may be significant for long-period transiting planets. These theoretical results are applicable to the modeling of planetary transits and precise Doppler measurements as well as analysis of pulsar and eclipsing binary timing observations.

  16. MERLIN observations of water maser proper motions in VY Canis Majoris

    Science.gov (United States)

    Richards, A. M. S.; Yates, J. A.; Cohen, R. J.

    1998-09-01

    MERLIN observations of the 22-GHz water masers in the circumstellar envelope of the supergiant VY CMa show an ellipsoidal distribution with a maximum extent of 700 mas east-west and 400 mas north-south. Comparison with observations made nine years earlier shows that the majority of maser features have survived and show proper motions throughout the region. The mean change in position is 28 mas and the proper motions are generally directed away from the assumed stellar position, and tend to be larger for features at greater projected distances. If the H_2O maser region is modelled as a partially filled thick spherical shell, and VY CMa is at a distance of 1.5 kpc, then the proper motion velocities in the direction of expansion are between 8kms^-1 at a distance of 75 mas from the assumed stellar position and 32kms^-1 at 360 mas. These velocities are consistent with the H_2O maser spectral line velocities which correspond to a maximum expansion velocity of 36kms^-1 at 400 mas from the assumed stellar position. These observations are consistent with radiation pressure on dust providing the force to accelerate the stellar wind as it passes through the H_2O maser shell. The H_2O maser region is elongated in the same direction as the dusty nebula around VY CMa. The water masers illuminate the small-scale dynamics and clumpiness which show the role of dust in driving the outflow. The overall ellipsoidal shape may be due to properties of the dust, such as its behaviour in the stellar magnetic field, or to interaction between the wind and circumstellar material. Maser monitoring also shows the difference between changes on the time-scale of stellar variability (a few years) and possible stages in the evolution of VY CMa to its likely fate as a supernova.

  17. Statistical HR diagrams for one hundred and fifteen thousand proper-motion stars

    International Nuclear Information System (INIS)

    Luyten, W.J.

    1978-01-01

    Since regular HR diagrams require apparent magnitudes, colors or spectra, and parallaxes, and such complete data are available for relatively few stars, there may be some advantage in making up diagrams which utilize proper motions instead of parallaxes, and are thus statistically similar to an HR diagram. The reduced proper motion, first used by Hertzsprung, is defined as H=m+5+5log μ, but may also be written as H=M+5log T, where T is the tangential velocity, and is expressed in astronomical units per year. A diagram plotting H against color will thus contain the considerable dispersion in tangential velocity which is a serious disadvantage. However, this is outweighed by two practical advantages. First, the one and the same person who does the proper motion survey can, and does also determine the other two quantities needed. Second, when using data obtained from such a proper motion survey one deals, statistically, with all the stars within a given distance and the results, therefore, are much more representative of the real situation in space than many HR diagrams which often contain an unrealistic preponderance of giants. (Auth.)

  18. Positions and proper motions of dwarf carbon stars

    Science.gov (United States)

    Deutsch, Eric W.

    1994-01-01

    Recent-epochs positions and proper motions of nine dwarf carbon star candidates are presented along with finding charts for each object. Measurements are obtained from digitized Palomar Observatory Sky Survey (POSS) and Quik V plate archives at the Space Telescope Science Institute, and from recent CCD images.

  19. UCAC3 PROPER MOTION SURVEY. II. DISCOVERY OF NEW PROPER MOTION STARS IN UCAC3 WITH 0.''40 yr–1 > μ ≥ 0.''18 yr–1 BETWEEN DECLINATIONS –47° and 00°

    International Nuclear Information System (INIS)

    Finch, Charlie T.; Zacharias, Norbert; Boyd, Mark R.; Henry, Todd J.; Hambly, Nigel C.

    2012-01-01

    We present 474 new proper motion stellar systems in the southern sky having no previously known components, with 0.''40 yr –1 >μ ≥ 0.''18 yr –1 between declinations –47° and 0°. In this second paper utilizing the U.S. Naval Observatory third CCD Astrograph Catalog (UCAC3) we complete our sweep of the southern sky for objects in the proper motion range targeted by this survey with R magnitudes ranging from 9.80 to 19.61. The new systems contribute a ∼16% increase in the number of new stellar systems for the same region of sky reported in previous SuperCOSMOS Research Consortium On Nearby Stars (RECONS) surveys. Among the newly discovered stellar systems are 16 multiples, plus an additional ten components that are new common proper motion companions to previously known objects. A comparison of UCAC3 proper motions to those from Hipparcos, Tycho-2, Southern Proper Motion, and SuperCOSMOS indicates that all proper motions are consistent to ∼10 mas yr –1 , with the exception of SuperCOSMOS. Distance estimates are derived for all stellar systems having SuperCOSMOS Sky Survey B J , R 59F , and I IVN plate magnitudes and Two Micron All Sky Survey (2MASS) infrared photometry. We find five new red dwarf systems estimated to be within 25 pc. These discoveries support results from previous proper motion surveys suggesting that more nearby stellar systems are to be found, particularly in the fainter, slower moving samples. In this second paper utilizing the UCAC3 we complete our sweep of the southern sky for objects in the proper motion range targeted by this survey with R magnitudes ranging from 9.80 to 19.61.

  20. MOTION VERIFIED RED STARS (MoVeRS): A CATALOG OF PROPER MOTION SELECTED LOW-MASS STARS FROM WISE, SDSS, AND 2MASS

    Energy Technology Data Exchange (ETDEWEB)

    Theissen, Christopher A.; West, Andrew A. [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Dhital, Saurav, E-mail: ctheisse@bu.edu [Department of Physical Sciences, Embry-Riddle Aeronautical University, 600 South Clyde Morris Blvd., Daytona Beach, FL 32114 (United States)

    2016-02-15

    We present a photometric catalog of 8,735,004 proper motion selected low-mass stars (KML-spectral types) within the Sloan Digital Sky Survey (SDSS) footprint, from the combined SDSS Data Release 10 (DR10), Two Micron All-Sky Survey (2MASS) point-source catalog (PSC), and Wide-field Infrared Survey Explorer (WISE) AllWISE catalog. Stars were selected using r − i, i − z, r − z, z − J, and z − W1 colors, and SDSS, WISE, and 2MASS astrometry was combined to compute proper motions. The resulting 3,518,150 stars were augmented with proper motions for 5,216,854 earlier type stars from the combined SDSS and United States Naval Observatory B1.0 catalog (USNO-B). We used SDSS+USNO-B proper motions to determine the best criteria for selecting a clean sample of stars. Only stars whose proper motions were greater than their 2σ uncertainty were included. Our Motion Verified Red Stars catalog is available through SDSS CasJobs and VizieR.

  1. Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey

    International Nuclear Information System (INIS)

    Skinner, Julie N.; Morgan, Dylan P.; West, Andrew A.; Lépine, Sébastien; Thorstensen, John R.

    2017-01-01

    We present an activity and kinematic analysis of high proper motion white dwarf-M dwarf binaries (WD+dMs) found in the SUPERBLINK survey, 178 of which are new identifications. To identify WD+dMs, we developed a UV–optical–IR color criterion and conducted a spectroscopic survey to confirm each candidate binary. For the newly identified systems, we fit the two components using model white dwarf spectra and M dwarf template spectra to determine physical parameters. We use H α chromospheric emission to examine the magnetic activity of the M dwarf in each system, and investigate how its activity is affected by the presence of a white dwarf companion. We find that the fraction of WD+dM binaries with active M dwarfs is significantly higher than their single M dwarf counterparts at early and mid-spectral types. We corroborate previous studies that find high activity fractions at both close and intermediate separations. At more distant separations, the binary fraction appears to approach the activity fraction for single M dwarfs. Using derived radial velocities and the proper motions, we calculate 3D space velocities for the WD+dMs in SUPERBLINK. For the entire SUPERBLINK WD+dMs, we find a large vertical velocity dispersion, indicating a dynamically hotter population compared to high proper motion samples of single M dwarfs. We compare the kinematics for systems with active M dwarfs and those with inactive M dwarfs, and find signatures of asymmetric drift in the inactive sample, indicating that they are drawn from an older population.

  2. Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Julie N. [Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Morgan, Dylan P.; West, Andrew A. [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Lépine, Sébastien [Department of Physics and Astronomy, Georgia State University, 25 Park Place NE, Atlanta, GA, 30303 (United States); Thorstensen, John R., E-mail: jskinner@bu.edu [Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755 (United States)

    2017-09-01

    We present an activity and kinematic analysis of high proper motion white dwarf-M dwarf binaries (WD+dMs) found in the SUPERBLINK survey, 178 of which are new identifications. To identify WD+dMs, we developed a UV–optical–IR color criterion and conducted a spectroscopic survey to confirm each candidate binary. For the newly identified systems, we fit the two components using model white dwarf spectra and M dwarf template spectra to determine physical parameters. We use H α chromospheric emission to examine the magnetic activity of the M dwarf in each system, and investigate how its activity is affected by the presence of a white dwarf companion. We find that the fraction of WD+dM binaries with active M dwarfs is significantly higher than their single M dwarf counterparts at early and mid-spectral types. We corroborate previous studies that find high activity fractions at both close and intermediate separations. At more distant separations, the binary fraction appears to approach the activity fraction for single M dwarfs. Using derived radial velocities and the proper motions, we calculate 3D space velocities for the WD+dMs in SUPERBLINK. For the entire SUPERBLINK WD+dMs, we find a large vertical velocity dispersion, indicating a dynamically hotter population compared to high proper motion samples of single M dwarfs. We compare the kinematics for systems with active M dwarfs and those with inactive M dwarfs, and find signatures of asymmetric drift in the inactive sample, indicating that they are drawn from an older population.

  3. Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project

    Science.gov (United States)

    de Bruijne, J. H. J.; Eilers, A.-C.

    2012-10-01

    Context. The Hundred-Thousand-Proper-Motion (HTPM) project will determine the proper motions of ~113 500 stars using a ~23-year baseline. The proper motions will be based on space-based measurements exclusively, with the Hipparcos data, with epoch 1991.25, as first epoch and with the first intermediate-release Gaia astrometry, with epoch ~2014.5, as second epoch. The expected HTPM proper-motion standard errors are 30-190 μas yr-1, depending on stellar magnitude. Aims: Depending on the astrometric characteristics of an object, in particular its distance and velocity, its radial velocity can have a significant impact on the determination of its proper motion. The impact of this perspective acceleration is largest for fast-moving, nearby stars. Our goal is to determine, for each star in the Hipparcos catalogue, the radial-velocity standard error that is required to guarantee a negligible contribution of perspective acceleration to the HTPM proper-motion precision. Methods: We employ two evaluation criteria, both based on Monte-Carlo simulations, with which we determine which stars need to be spectroscopically (re-)measured. Both criteria take the Hipparcos measurement errors into account. The first criterion, the Gaussian criterion, is applicable to nearby stars. For distant stars, this criterion works but returns overly pessimistic results. We therefore use a second criterion, the robust criterion, which is equivalent to the Gaussian criterion for nearby stars but avoids biases for distant stars and/or objects without literature radial velocity. The robust criterion is hence our prefered choice for all stars, regardless of distance. Results: For each star in the Hipparcos catalogue, we determine the confidence level with which the available radial velocity and its standard error, taken from the XHIP compilation catalogue, are acceptable. We find that for 97 stars, the radial velocities available in the literature are insufficiently precise for a 68.27% confidence

  4. Evidence of small-scale magnetic concentrations dragged by vortex motion of solar photospheric plasma

    Science.gov (United States)

    Balmaceda, L.; Vargas Domínguez, S.; Palacios, J.; Cabello, I.; Domingo, V.

    2010-04-01

    Vortex-type motions have been measured by tracking bright points in high-resolution observations of the solar photosphere. These small-scale motions are thought to be determinant in the evolution of magnetic footpoints and their interaction with plasma and therefore likely to play a role in heating the upper solar atmosphere by twisting magnetic flux tubes. We report the observation of magnetic concentrations being dragged towards the center of a convective vortex motion in the solar photosphere from high-resolution ground-based and space-borne data. We describe this event by analyzing a series of images at different solar atmospheric layers. By computing horizontal proper motions, we detect a vortex whose center appears to be the draining point for the magnetic concentrations detected in magnetograms and well-correlated with the locations of bright points seen in G-band and CN images.

  5. Corrections to the Hipparcos proper motions in declination for 807 stars

    Directory of Open Access Journals (Sweden)

    Damljanović G.

    2008-01-01

    Full Text Available We used the data on latitude variations obtained from observations with 10 classical photographic zenith tubes (PZT in order to improve the Hipparcos proper motions in declinations µδ for 807 stars. Part of observing programmes, carried out during the last century for the purpose of studying the Earth's rotation, were realized by using PZT instruments. These observations were performed within in the intervals (tens of years much longer than that of the Hipparcos mission (less than 4 years. In addition, the annual number of observations for every PZT programme star is several hundreds on the average. Though the accuracy of the star coordinates in the Hipparcos Catalogue is by two orders of magnitude better than that of the star coordinates from the PZT observations, the large number of observations performed a much longer time interval makes it possible to correct the Hipparcos proper motions and to improve their accuracy with respect to the accuracy given in the Hipparcos Catalogue. Long term examinations of latitude and time variations were used to form the Earth Orientation Catalogue (EOC-2, aimed at a more accurate determination of positions and proper motions for the stars included. Our method of calculating the corrections of the proper motions in declination from the latitude variations is different from the method used in obtaining the EOC-2 Catalogue. Comparing the results we have established a good agreement between our µδ and the EOC-2 ones for the star sample used in the present paper.

  6. Corrections to the Hipparcos Proper Motions in Declination for 807 Stars

    Directory of Open Access Journals (Sweden)

    Damljanović, G.

    2008-12-01

    Full Text Available We used the data on latitude variations obtained from observations with 10 classical photographic zenith tubes (PZT in order to improve the Hipparcos proper motions in declinations $mu_{delta} $ for 807 stars. Part of observing programmes, carried out during the last century for the purpose of studying the Earth's rotation, were realized by using PZT instruments. These observations were performed within in the intervals (tens of years much longer than that of the Hipparcos mission (less than 4 years. In addition, the annual number of observations for every PZT-programme star is several hundreds on the average. Though the accuracy of the star coordinates in the Hipparcos Catalogue is by two orders of magnitude better than that of the star coordinates from the PZT observations, the large number of observations performed a much longer time interval makes it possible to correct the Hipparcos proper motions and to improve their accuracy with respect to the accuracy given in the Hipparcos Catalogue. Long term examinations of latitude and time variations were used to form the Earth Orientation Catalogue (EOC-2, aimed at a more accurate determination of positions and proper motions for the stars included. Our method of calculating the corrections of the proper motions in declination from the latitude variations is different from the method used in obtaining the EOC-2 Catalogue. Comparing the results we have established a good agreement between our $mu_ {delta} $ and the EOC-2 ones for the star sample used in the present paper.

  7. MEASURING THE UNDETECTABLE: PROPER MOTIONS AND PARALLAXES OF VERY FAINT SOURCES

    International Nuclear Information System (INIS)

    Lang, Dustin; Hogg, David W.; Jester, Sebastian; Rix, Hans-Walter

    2009-01-01

    The near future of astrophysics involves many large solid-angle, multi-epoch, multiband imaging surveys. These surveys will, at their faint limits, have data on a large number of sources that are too faint to be detected at any individual epoch. Here, we show that it is possible to measure in multi-epoch data not only the fluxes and positions, but also the parallaxes and proper motions of sources that are too faint to be detected at any individual epoch. The method involves fitting a model of a moving point source simultaneously to all imaging, taking account of the noise and point-spread function (PSF) in each image. By this method it is possible to measure the proper motion of a point source with an uncertainty close to the minimum possible uncertainty given the information in the data, which is limited by the PSF, the distribution of observation times (epochs), and the total signal-to-noise in the combined data. We demonstrate our technique on multi-epoch Sloan Digital Sky Survey (SDSS) imaging of the SDSS Southern Stripe (SDSSSS). We show that with our new technique we can use proper motions to distinguish very red brown dwarfs from very high-redshift quasars in these SDSS data, for objects that are inaccessible to traditional techniques, and with better fidelity than by multiband imaging alone. We rediscover all 10 known brown dwarfs in our sample and present nine new candidate brown dwarfs, identified on the basis of significant proper motion.

  8. PROPER MOTIONS OF YOUNG STELLAR OUTFLOWS IN THE MID-INFRARED WITH SPITZER (IRAC). I. THE NGC 1333 REGION

    International Nuclear Information System (INIS)

    Raga, A. C.; Noriega-Crespo, A.; Carey, S. J.; Arce, H. G.

    2013-01-01

    We use two 4.5 μm Spitzer (IRAC) maps of the NGC 1333 region taken over a ∼7 yr interval to determine proper motions of its associated outflows. This is a first successful attempt at obtaining proper motions of stellars' outflow from Spitzer observations. For the outflow formed by the Herbig-Haro objects HH7, 8, and 10, we find proper motions of ∼9-13 km s –1 , which are consistent with previously determined optical proper motions of these objects. We determine proper motions for a total of eight outflows, ranging from ∼10 to 100 km s –1 . The derived proper motions show that out of these eight outflows, three have tangential velocities ≤20 km s –1 . This result shows that a large fraction of the observed outflows have low intrinsic velocities and that the low proper motions are not merely a projection effect.

  9. Possible Relativistic Definitions of Parallax, Proper Motion and Radial Velocity

    National Research Council Canada - National Science Library

    Klioner, S

    2000-01-01

    .... In this paper, the authors briefly describe a relativistic model of space-based optical positional observations valid at a high level of accuracy, and suggest definitions of parallax, proper motion...

  10. Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey

    Science.gov (United States)

    Skinner, Julie N.; Morgan, Dylan P.; West, Andrew A.; Lépine, Sébastien; Thorstensen, John R.

    2017-09-01

    We present an activity and kinematic analysis of high proper motion white dwarf-M dwarf binaries (WD+dMs) found in the SUPERBLINK survey, 178 of which are new identifications. To identify WD+dMs, we developed a UV-optical-IR color criterion and conducted a spectroscopic survey to confirm each candidate binary. For the newly identified systems, we fit the two components using model white dwarf spectra and M dwarf template spectra to determine physical parameters. We use Hα chromospheric emission to examine the magnetic activity of the M dwarf in each system, and investigate how its activity is affected by the presence of a white dwarf companion. We find that the fraction of WD+dM binaries with active M dwarfs is significantly higher than their single M dwarf counterparts at early and mid-spectral types. We corroborate previous studies that find high activity fractions at both close and intermediate separations. At more distant separations, the binary fraction appears to approach the activity fraction for single M dwarfs. Using derived radial velocities and the proper motions, we calculate 3D space velocities for the WD+dMs in SUPERBLINK. For the entire SUPERBLINK WD+dMs, we find a large vertical velocity dispersion, indicating a dynamically hotter population compared to high proper motion samples of single M dwarfs. We compare the kinematics for systems with active M dwarfs and those with inactive M dwarfs, and find signatures of asymmetric drift in the inactive sample, indicating that they are drawn from an older population. Based on observations obtained at the MDM Observatory operated by Dartmouth College, Columbia University, The Ohio State University, and the University of Michigan.

  11. UCAC3 Proper Motion Survey. I. Discovery of New Proper Motion Stars in UCAC3 With 0.40/yr mu 0.18/yr Between Declinations -90 deg and -47 deg

    Science.gov (United States)

    2010-09-01

    overlooked during previous SCR and other searches. The Two-Micron All Sky Survey ( 2MASS ) was used to probe for and reduce systematic errors in UCAC CCD...of 50–200 mas, when compared to 2MASS data. For a detailed description of the derived UCAC3 proper motions see Zacharias et al. (2010). An effort was...meeting the declination and proper motion survey limits, all stars (1) must be in the 2MASS catalog with an e2mpho ( 2MASS photometry error) less than

  12. PROPER MOTIONS OF THE HH 110/270 SYSTEM

    International Nuclear Information System (INIS)

    Kajdič, P.; Reipurth, B.; Walawender, J.; Raga, A. C.; Bally, J.

    2012-01-01

    We present a study of the HH 110/270 system based on three sets of optical images obtained with the ESO New Technology Telescope, the Subaru Telescope, and the Hubble Space Telescope (HST). The ground-based observations are made in the Hα and [S II] emission lines and the HST observations are made in the Hα line only. Ground-based observations reveal the existence of nine knots, which have not been previously discussed and offer some important insight into the HH 110/270 history. We perform a kinematic study of the HH 110/270 system and an analysis of its emission properties. We measure proper motions of all the knots in the system. Four of the newly identified knots belong to the HH 270 jet. Their positions indicate that the jet's axis changed its direction in the past. We speculate that similar changes may have occurred many times in the past and this could be part of the reason for the unusual structure of the HH 110 jet. The HST observations allow us to resolve individual knots into their substructures and to measure their proper motions. These measurements show that the knots are highly turbulent structures. Finally, we report the discovery of four new Herbig-Haro (HH) objects located near the HH 110/270 system.

  13. Mass estimates from stellar proper motions: the mass of ω Centauri

    Science.gov (United States)

    D'Souza, Richard; Rix, Hans-Walter

    2013-03-01

    We lay out and apply methods to use proper motions of individual kinematic tracers for estimating the dynamical mass of star clusters. We first describe a simple projected mass estimator and then develop an approach that evaluates directly the likelihood of the discrete kinematic data given the model predictions. Those predictions may come from any dynamical modelling approach, and we implement an analytic King model, a spherical isotropic Jeans equation model and an axisymmetric, anisotropic Jeans equation model. This maximum likelihood modelling (MLM) provides a framework for a model-data comparison, and a resulting mass estimate, which accounts explicitly for the discrete nature of the data for individual stars, the varying error bars for proper motions of differing signal-to-noise ratio, and for data incompleteness. Both of these two methods are evaluated for their practicality and are shown to provide an unbiased and robust estimate of the cluster mass. We apply these approaches to the enigmatic globular cluster ω Centauri, combining the proper motion from van Leeuwen et al. with improved photometric cluster membership probabilities. We show that all mass estimates based on spherical isotropic models yield (4.55 ± 0.1) × 106 M⊙[D/5.5 ± 0.2 kpc]3, where our modelling allows us to show how the statistical precision of this estimate improves as more proper motion data of lower signal-to-noise ratio are included. MLM predictions, based on an anisotropic axisymmetric Jeans model, indicate for ω Cen that the inclusion of anisotropies is not important for the mass estimates, but that accounting for the flattening is: flattened models imply (4.05 ± 0.1) × 106 M⊙[D/5.5 ± 0.2 kpc]3, 10 per cent lower than when restricting the analysis to a spherical model. The best current distance estimates imply an additional uncertainty in the mass estimate of 12 per cent.

  14. Impact of quasar proper motions on the alignment between the International Celestial Reference Frame and the Gaia reference frame

    Science.gov (United States)

    Liu, J.-C.; Malkin, Z.; Zhu, Z.

    2018-03-01

    The International Celestial Reference Frame (ICRF) is currently realized by the very long baseline interferometry (VLBI) observations of extragalactic sources with the zero proper motion assumption, while Gaia will observe proper motions of these distant and faint objects to an accuracy of tens of microarcseconds per year. This paper investigates the difference between VLBI and Gaia quasar proper motions and it aims to understand the impact of quasar proper motions on the alignment of the ICRF and Gaia reference frame. We use the latest time series data of source coordinates from the International VLBI Service analysis centres operated at Goddard Space Flight Center (GSF2017) and Paris observatory (OPA2017), as well as the Gaia auxiliary quasar solution containing 2191 high-probability optical counterparts of the ICRF2 sources. The linear proper motions in right ascension and declination of VLBI sources are derived by least-squares fits while the proper motions for Gaia sources are simulated taking into account the acceleration of the Solar system barycentre and realistic uncertainties depending on the source brightness. The individual and global features of source proper motions in GSF2017 and OPA2017 VLBI data are found to be inconsistent, which may result from differences in VLBI observations, data reduction and analysis. A comparison of the VLBI and Gaia proper motions shows that the accuracies of the components of rotation and glide between the two systems are 2-4 μas yr- 1 based on about 600 common sources. For the future alignment of the ICRF and Gaia reference frames at different wavelengths, the proper motions of quasars must necessarily be considered.

  15. When Things Don’t Look Right: What Appear to be Proper Motion Discrepancies in the WDS

    Science.gov (United States)

    Harshaw, Richard

    2017-10-01

    Proper motion data for double stars are included for most of the records in the Washington Double Star Catalog (WDS). In many cases, the proper motion data agree well with the observed changes in the system over time. But in other cases, the proper motion data do not align well with the observations. It is therefore incumbent on the double star researcher to treat any research based on proper motions with caution to be sure that wrong conclusions are not drawn. Possible reasons for such discrepancies are explored.

  16. PROPER MOTIONS OF THE HH 110/270 SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Kajdic, P. [Instituto de Astronomia, UNAM, Mexico D.F. (Mexico); Reipurth, B.; Walawender, J. [Institute for Astronomy, University of Hawaii at Manoa, 640 N. A' ohoku Place, Hilo, HI 96720 (United States); Raga, A. C. [Instituto de Ciencias Nucleares, UNAM, Mexico D.F. (Mexico); Bally, J., E-mail: primoz@geofisica.unam.mx, E-mail: reipurth@IfA.Hawaii.Edu, E-mail: raga@nucleares.unam.mx, E-mail: John.Bally@casa.colorado.edu, E-mail: joshw@ifa.hawaii.edu [CASA, University of Colorado, 389 UCB, Boulder, CO 80309-0389 (United States)

    2012-05-15

    We present a study of the HH 110/270 system based on three sets of optical images obtained with the ESO New Technology Telescope, the Subaru Telescope, and the Hubble Space Telescope (HST). The ground-based observations are made in the H{alpha} and [S II] emission lines and the HST observations are made in the H{alpha} line only. Ground-based observations reveal the existence of nine knots, which have not been previously discussed and offer some important insight into the HH 110/270 history. We perform a kinematic study of the HH 110/270 system and an analysis of its emission properties. We measure proper motions of all the knots in the system. Four of the newly identified knots belong to the HH 270 jet. Their positions indicate that the jet's axis changed its direction in the past. We speculate that similar changes may have occurred many times in the past and this could be part of the reason for the unusual structure of the HH 110 jet. The HST observations allow us to resolve individual knots into their substructures and to measure their proper motions. These measurements show that the knots are highly turbulent structures. Finally, we report the discovery of four new Herbig-Haro (HH) objects located near the HH 110/270 system.

  17. VizieR Online Data Catalog: Proper motions in M 11 (Su+ 1998)

    Science.gov (United States)

    Su, C.-G.; Zhao, J.-L.; Tian, K.-P.

    1997-07-01

    Relative proper motions of 872 stars in the open cluster M 11 region are reduced using 10 plate pairs taken over time baselines of 16~70 years with the double astrograph telescope of Shanghai Observatory. The scale is 30"/mm. The plates were measured with the PDS machines in the Purple Mountain Observatory in Nanjing and the Institute of Technology and Communication in Luoyang, China. The average proper motion accuracy is about 1.1mas/yr with 85% of the data better than 1mas/yr. Membership probabilities of 785 stars within 25' centred on M 11 are determined based on their proper motions. The method used is suggested by Su et al. (1995AcApS..15..217S) with some improvements of Zhao & He (1990A&A...237...54Z), in which the space distribution and magnitude dependencies for cluster stars are taken into account. The results are significantly good. The total integrated membership probabilities for all these stars is 547 and the number of stars with probabilities higher than 0.7 is 541. It can be found after the membership determination that there exists mass segregation in M 11. Some comparisons and discussion are also given. (1 data file).

  18. The VMC survey. XXX. Stellar proper motions in the central parts of the Small Magellanic Cloud

    Science.gov (United States)

    Niederhofer, F.; Cioni, M.-R. L.; Rubele, S.; Schmidt, T.; Bekki, K.; Grijs, R. de; Emerson, J.; Ivanov, V. D.; Marconi, M.; Oliveira, J. M.; Petr-Gotzens, M. G.; Ripepi, V.; van Loon, J. Th.; Zaggia, S.

    2018-05-01

    We present the first spatially resolved map of stellar proper motions within the central ( 3.1 × 2.4 kpc) regions of the Small Magellanic Cloud (SMC). The data used for this study encompasses four tiles from the ongoing near-infrared VISTA survey of the Magellanic Clouds system and covers a total contiguous area on the sky of 6.81 deg2. Proper motions have been calculated independently in two dimensions from the spatial offsets in the Ks filter over time baselines between 22 and 27 months. The reflex motions of approximately 33 000 background galaxies are used to calibrate the stellar motions to an absolute scale. The resulting catalog is composed of more than 690 000 stars which have been selected based on their position in the (J - Ks, Ks) color-magnitude diagram. For the median absolute proper motion of the SMC, we find (μαcos(δ), μδ) = (1.087 ± 0.192 (sys.) ± 0.003 (stat.), -1.187 ± 0.008 (sys.) ± 0.003 (stat.)) mas yr-1, consistent with previous studies. Mapping the proper motions as a function of position within the SMC reveals a nonuniform velocity pattern indicative of a tidal feature behind the main body of the SMC and a flow of stars in the south-east moving predominantly along the line-of-sight. Based on observations made with VISTA at the Paranal Observatory under program ID 179.B-2003.

  19. Chemically Dissected Rotation Curves of the Galactic Bulge from Main-sequence Proper Motions

    Science.gov (United States)

    Clarkson, William I.; Calamida, Annalisa; Sahu, Kailash C.; Brown, Thomas M.; Gennaro, Mario; Avila, Roberto J.; Valenti, Jeff; Debattista, Victor P.; Rich, R. Michael; Minniti, Dante; Zoccali, Manuela; Aufdemberge, Emily R.

    2018-05-01

    We report results from an exploratory study implementing a new probe of Galactic evolution using archival Hubble Space Telescope imaging observations. Precise proper motions are combined with photometric relative metallicity and temperature indices, to produce the proper-motion rotation curves of the Galactic bulge separately for metal-poor and metal-rich main-sequence samples. This provides a “pencil-beam” complement to large-scale wide-field surveys, which to date have focused on the more traditional bright giant branch tracers. We find strong evidence that the Galactic bulge rotation curves drawn from “metal-rich” and “metal-poor” samples are indeed discrepant. The “metal-rich” sample shows greater rotation amplitude and a steeper gradient against line-of-sight distance, as well as possibly a stronger central concentration along the line of sight. This may represent a new detection of differing orbital anisotropy between metal-rich and metal-poor bulge objects. We also investigate selection effects that would be implied for the longitudinal proper-motion cut often used to isolate a “pure-bulge” sample. Extensive investigation of synthetic stellar populations suggests that instrumental and observational artifacts are unlikely to account for the observed rotation curve differences. Thus, proper-motion-based rotation curves can be used to probe chemodynamical correlations for main-sequence tracer stars, which are orders of magnitude more numerous in the Galactic bulge than the bright giant branch tracers. We discuss briefly the prospect of using this new tool to constrain detailed models of Galactic formation and evolution. Based on observations made with the NASA/ESA Hubble Space Telescope and obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  20. FIRST RESULTS FROM Pan-STARRS1: FAINT, HIGH PROPER MOTION WHITE DWARFS IN THE MEDIUM-DEEP FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    Tonry, J. L.; Flewelling, H. A.; Deacon, N. R.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Kudritzki, R.-P.; Hodapp, K. W.; Magnier, E. A.; Morgan, J. S.; Wainscoat, R. J. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Stubbs, C. W.; Kilic, M.; Chornock, R.; Berger, E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Price, P. A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

    2012-01-20

    The Pan-STARRS1 survey has obtained multi-epoch imaging in five bands (Pan-STARRS1 g{sub P1}, r{sub P1}, i{sub P1}, z{sub P1}, and y{sub P1}) on 12 'Medium-Deep fields', each of which spans a 3.{sup 0}3 circle. For the period between 2009 April and 2011 April these fields were observed 50-200 times. Using a reduced proper motion diagram, we have extracted a list of 47 white dwarf (WD) candidates whose Pan-STARRS1 astrometry indicates a non-zero proper motion at the 6{sigma} level, with a typical 1{sigma} proper motion uncertainty of 10 mas yr{sup -1}. We also used astrometry from the Sloan Digital Sky Survey (when available) and USNO-B to assess our proper motion fits. None of the WD candidates exhibits evidence of statistically significant parallaxes, with a typical 1{sigma} uncertainty of 8 mas. Twelve of these candidates are known WDs, including the high proper motion (1.''7 yr{sup -1}) WD LHS 291. We confirm seven more objects as WDs through optical spectroscopy. Based on the Pan-STARRS1 colors, ten of the stars are likely to be cool WDs with 4170 K proper motion WDs that are part of the old thick disk and halo.

  1. THE PROPER MOTIONS OF THE DOUBLE RADIO SOURCE n IN THE ORION BN/KL REGION

    International Nuclear Information System (INIS)

    Rodríguez, Luis F.; Loinard, Laurent; Zapata, Luis; Lizano, Susana; Dzib, Sergio A.; Menten, Karl M.; Gómez, Laura

    2017-01-01

    We have extended the time baseline for observations of the proper motions of radio sources in the Orion BN/KL region from 14.7 to 22.5 years. We present improved determinations for the sources BN and I. In addition, we address the proper motions of the double radio source n, that have been questioned in the literature. We confirm that all three sources are moving away at transverse velocities of tens of kilometers per second from a region in-between them, where they were located about 500 years ago. Source n exhibits a new component that we interpret as due to a one-sided ejection of free–free emitting plasma that took place after 2006.36. We used the highly accurate relative proper motions between sources BN and I to determine that their closest separation took place in the year 1475 ± 6, when they were within ∼100 au or less from each other in the plane of the sky.

  2. THE PROPER MOTIONS OF THE DOUBLE RADIO SOURCE n IN THE ORION BN/KL REGION

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez, Luis F.; Loinard, Laurent; Zapata, Luis; Lizano, Susana [Instituto de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72 (Xangari), 58089 Morelia, Michoacán, México (Mexico); Dzib, Sergio A.; Menten, Karl M. [Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Gómez, Laura, E-mail: l.rodriguez@crya.unam.mx [Joint ALMA Observatory, Alonso de Córdoba 3107, Vitacura, Santiago (Chile)

    2017-01-10

    We have extended the time baseline for observations of the proper motions of radio sources in the Orion BN/KL region from 14.7 to 22.5 years. We present improved determinations for the sources BN and I. In addition, we address the proper motions of the double radio source n, that have been questioned in the literature. We confirm that all three sources are moving away at transverse velocities of tens of kilometers per second from a region in-between them, where they were located about 500 years ago. Source n exhibits a new component that we interpret as due to a one-sided ejection of free–free emitting plasma that took place after 2006.36. We used the highly accurate relative proper motions between sources BN and I to determine that their closest separation took place in the year 1475 ± 6, when they were within ∼100 au or less from each other in the plane of the sky.

  3. Parallaxes and Proper Motions From the MCCormick Observatory: List 47

    Science.gov (United States)

    Ianna, Philip A.; Patterson, Richard J.; Swain, Melanie A.

    1996-01-01

    Trigonometric parallaxes and proper motions are presented for 32 late-type stars observed photographically with the Leander McCormick 67 cm refractor. Eighteen of the stars have no previously published parallaxes. Twenty one of the stars are K and M dwarfs identified by Vyssotsky and his collaborators. The list includes several x-ray luminous M dwarfs, a rapidly rotating spotted flare star, and two astrometric binaries.

  4. uvby photometry in McCormick proper motion fields

    Science.gov (United States)

    Degewij, J.

    1982-01-01

    The Danish 50 cm telescope at the European Southern Observatory was used to obtain high-precision uvby photometry for 50 F2 to G2 stars, with V values in the 9.4-12.3 mag range, which were selected in the southern galactic polar regions of the McCormick proper motion fields and measured on six different nights. The brighter stars are found to systematically exhibit smaller m(1) indices, of about 0.02 mag, upon comparison with the earlier data of Blaauw et al (1976). Single measurements are given for 98 stars in eight McCormick fields at intermediate southern galactic latitudes.

  5. Determination of Proper Motions of Circumpolar Stars by Using Images from Ukrvo Plate Archives

    Science.gov (United States)

    Protsyuk, Yu.; Andruk, V.; Mazhaev, A.; Kovylianska, O.; Protsyuk, S.; Golovnya, V.

    UkrVO plate archives contain informationobtained at different time periods and in different observatories for the same regions of the sky [3, 5, 6, 7, 8]. It allows us to carry out joint processing of plates and to receive new results for interesting objects. To obtain proper motions of stars in circumpolar areas, we selected 34 photographic plates from the RI NAO archive and 161 plates from the archive of the MAO NAS. A mean epoch difference between the plates from these archives is 55 years. Scanning of the plates and data processing were independently carried out by both observatories. A catalog of equatorial positions for 195 thousand stars up to 15m was compiled in the RI NAO (black dots in Fig. 1). A catalog of equatorial positions for 1050 thousand stars up to 16.5m was compiled in MAO (gray dots in Fig. 1). A comparison of positions for common stars contained in these catalogs was conducted. A catalog of proper motions for 30 thousand common stars up to 15m was compiled using these two input catalogs. The obtained result suggests the advisability of processing of all observations to receive proper motions of stars up to 14-15m in the declination zone of 65° to 90°.

  6. Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. IV. Measurement for Sculptor

    Science.gov (United States)

    Piatek, Slawomir; Pryor, Carlton; Bristow, Paul; Olszewski, Edward W.; Harris, Hugh C.; Mateo, Mario; Minniti, Dante; Tinney, Christopher G.

    2006-03-01

    This article presents a measurement of the proper motion of the Sculptor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope using the Space Telescope Imaging Spectrograph in the imaging mode. Each of two distinct fields contains a quasi-stellar object that serves as the ``reference point.'' The measured proper motion of Sculptor, expressed in the equatorial coordinate system, is (μα, μδ)=(9+/-13, 2+/-13) mas century-1. Removing the contributions from the motion of the Sun and the motion of the local standard of rest produces the proper motion in the Galactic rest frame: (μGrfα, μGrfδ)=(-23+/-13, 45+/-13) mas century-1. The implied space velocity with respect to the Galactic center has a radial component of Vr=79+/-6 km s-1 and a tangential component of Vt=198+/-50 km s-1. Integrating the motion of Sculptor in a realistic potential for the Milky Way produces orbital elements. The perigalacticon and apogalacticon are 68 (31, 83) and 122 (97, 313) kpc, respectively, where the values in the parentheses represent the 95% confidence interval derived from Monte Carlo experiments. The eccentricity of the orbit is 0.29 (0.26, 0.60), and the orbital period is 2.2 (1.5, 4.9) Gyr. Sculptor is on a polar orbit around the Milky Way: the angle of inclination is 86° (83°, 90°). Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  7. VizieR Online Data Catalog: The VLBA Extragalactic Proper Motion Catalog (Truebenbach+, 2017)

    Science.gov (United States)

    Truebenbach, A. E.; Darling, J.

    2017-11-01

    We created our catalog of extragalactic radio proper motions using the 2017a Goddard VLBI global solution. The 2017a solution is computed from more than 30 years of dual-band VLBI observations --1979 August 3 to 2017 March 27. We also observed 28 objects with either no redshift or a "questionable" Optical Characteristic of Astrometric Radio Sources (OCARS; Malkin 2016ARep...60..996M) redshift at the Apache Point Observatory (APO) 3.5m telescope and/or at Gemini North. We conducted observations on the 3.5m telescope at Apache Point Observatory with the Dual Imaging Spectrograph (DIS) from 2015 April 18 to 2016 June 30. We chose two objects for additional observations with the Gemini Multi-Object Spectrograph-North (GMOS-N) at Gemini North Observatory. 2021+317 was observed on 2016 June 26 and 28, while 0420+417 was observed on 2016 November 8 and 26. We also observed 42 radio sources with the Very Long Baseline Array (VLBA) in the X-band (3.6cm/8.3GHz). Our targets had all been previously observed by VLBI. Our VLBA observations were conducted in two campaigns from 2015 September to 2016 January and 2016 October to November. The final extragalactic proper motion catalog (created primarily from archival Goddard VLBI data, with redshifts obtained from OCARS) contains 713 proper motions with average uncertainties of 24μas/yr. (5 data files).

  8. Proper motion separation of Be stars in the Milky Way and the Magellanic Clouds

    Science.gov (United States)

    Vieira, K.; García, A.; Sabogal, B.

    2018-01-01

    We present a proper motion investigation of a sample of Be stars candidates towards the Large Magellanic Cloud (LMC), which has resulted in the identification of two separate populations, in the Galactic foreground and in the Magellanic background. OGLE BVI and 2MASS JHK photometry were used with the SPM4 proper motions to discriminate the different populations located towards the LMC. Two populations with distinctive infrared colours and noticeable different kinematics were found, the bluer sample is consistent with being in the LMC and the redder one with belonging to the Milky Way (MW) disk. This settles the nature of the redder sample which had been described in previous publications as a possible unknown subclass of stars among the Be candidates in the LMC.

  9. Kinematics of Local, High-Velocity K dwarfs in the SUPERBLINK Proper Motion Catalog

    Science.gov (United States)

    Kim, Bokyoung; Lepine, Sebastien

    2018-01-01

    We present a study of the kinematics of 345,480 K stars within 2 kpc of the Sun, based on data from the SUPERBLINK catalog of stars with high proper motions (> 40 mas/yr), combined with data from the 2MASS survey and from the first GAIA release, which together yields proper motions accurate to ~2 mas/yr. All K dwarfs were selected based on their G-K colors, and photometric distances were estimated from a re-calibrated color-magnitude relationship for K dwarfs. We plot transverse velocities VT in various directions on the sky, to examine the local distribution of K dwarfs in velocity space. We have also obtained radial velocity information for a subsample of 10,128 stars, from RAVE and SDSS DR12, which we use to construct spatial velocity (U, V, W) plots. About a third (123,350) of the stars are high-velocity K dwarfs, with motions consistent with the local Galactic halo population. Our kinematic analysis suggests that their velocity-space distribution is very uniform, and we find no evidence of substructure that might arise, e.g., from local streams or moving groups.

  10. PROPER MOTIONS OF THE OUTER KNOTS OF THE HH 80/81/80N RADIO-JET

    Energy Technology Data Exchange (ETDEWEB)

    Masqué, Josep M.; Rodriguez, Luis F.; Carrasco-González, Carlos [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Morelia 58089, México (Mexico); Araudo, Anabella [University of Oxford, Astrophysics, Keble Road, Oxford OX1 3RH (United Kingdom); Estalella, Robert [Departament d’Astronomia i Meteorologia and Institut de Ciències del Cosmos (IEEC-UB), Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona, Catalunya (Spain); Anglada, Guillem; Osorio, Mayra [Instituto de Astrofísica de Andalucía (CSIC), Apartado 3004, E-18080 Granada (Spain); Girart, Josep M. [Institut de Ciències de l’Espai (CSIC-IEEC), Campus UAB, Carrer de Can Magrans, S/N, E-08193 Cerdanyola del Vallès, Catalunya (Spain)

    2015-11-20

    The radio-knots of the Herbig–Haro (HH) 80/81/80N jet extend from the HH 80 object to the recently discovered Source 34 and has a total projected jet size of 10.3 pc, constituting the largest collimated radio-jet system known so far. It is powered by the bright infrared source IRAS 18162−2048 associated with a massive young stellar object. We report 6 cm JVLA observations that, compared with previous 6 cm VLA observations carried out in 1989, allow us to derive proper motions of the HH 80, HH 81, and HH 80N radio knots located about 2.5 pc away in projection from the powering source. For the first time, we measure proper motions of the optically obscured HH 80N object providing evidence that this knot, along with HH 81 and HH 80 are associated with the same radio-jet. We also confirm the presence of Source 34, located further north of HH 80N, previously proposed to belong to the jet.We derived that the tangential velocity of HH 80N is 260 km s{sup −1} and has a direction in agreement with the expected direction of a ballistic precessing jet. The HH 80 and HH 81 objects have tangential velocities of 350 and 220 km s{sup −1}, respectively, but their directions are somewhat deviated from the expected jet path. The velocities of the HH objects studied in this work are significantly lower than those derived for the radio knots of the jet close to the powering source (600–1400 km s{sup −1}) suggesting that the jet is slowing down due to a strong interaction with the ambient medium. As a result, since HH 80 and HH 81 are located near the edge of the cloud, the inhomogeneous and low density medium may contribute to skew the direction of their determined proper motions. The HH 80 and HH 80N emission at 6 cm is, at least in part, probably synchrotron radiation produced by relativistic electrons in a magnetic field of 1 mG. If these electrons are accelerated in a reverse adiabatic shock, we estimate a jet total density of ≲1000 cm{sup −3}. All of these

  11. A deep proper motion catalog within the Sloan digital sky survey footprint

    International Nuclear Information System (INIS)

    Munn, Jeffrey A.; Harris, Hugh C.; Tilleman, Trudy M.; Hippel, Ted von; Kilic, Mukremin; Liebert, James W.; Williams, Kurtis A.; DeGenarro, Steven; Jeffery, Elizabeth

    2014-01-01

    A new proper motion catalog is presented, combining the Sloan Digital Sky Survey (SDSS) with second epoch observations in the r band within a portion of the SDSS imaging footprint. The new observations were obtained with the 90prime camera on the Steward Observatory Bok 90 inch telescope, and the Array Camera on the U.S. Naval Observatory, Flagstaff Station, 1.3 m telescope. The catalog covers 1098 square degrees to r = 22.0, an additional 1521 square degrees to r = 20.9, plus a further 488 square degrees of lesser quality data. Statistical errors in the proper motions range from 5 mas year −1 at the bright end to 15 mas year −1 at the faint end, for a typical epoch difference of six years. Systematic errors are estimated to be roughly 1 mas year −1 for the Array Camera data, and as much as 2–4 mas year −1 for the 90prime data (though typically less). The catalog also includes a second epoch of r band photometry.

  12. A deep proper motion catalog within the Sloan digital sky survey footprint

    Energy Technology Data Exchange (ETDEWEB)

    Munn, Jeffrey A.; Harris, Hugh C.; Tilleman, Trudy M. [US Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86005-8521 (United States); Hippel, Ted von [Embry-Riddle Aeronautical University, Physical Sciences, 600 South Clyde Morris Boulevard Daytona Beach, FL 32114-3900 (United States); Kilic, Mukremin [University of Oklahoma, Homer L. Dodge Department of Physics and Astronomy, 440 West Brooks Street, Norman, OK 73019 (United States); Liebert, James W. [University of Arizona, Steward Observatory, Tucson, AZ 85721 (United States); Williams, Kurtis A. [Department of Physics and Astronomy, Texas A and M University-Commerce, P.O. Box 3011, Commerce, TX 75429 (United States); DeGenarro, Steven [Department of Astronomy, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712-0259 (United States); Jeffery, Elizabeth, E-mail: jam@nofs.navy.mil, E-mail: hch@nofs.navy.mil, E-mail: trudy@nofs.navy.mil, E-mail: ted.vonhippel@erau.edu, E-mail: kilic@ou.edu, E-mail: jamesliebert@gmail.com, E-mail: kurtis.williams@tamuc.edu, E-mail: studiofortytwo@yahoo.com, E-mail: ejeffery@byu.edu [BYU Department of Physics and Astronomy, N283 ESC, Provo, UT 84602 (United States)

    2014-12-01

    A new proper motion catalog is presented, combining the Sloan Digital Sky Survey (SDSS) with second epoch observations in the r band within a portion of the SDSS imaging footprint. The new observations were obtained with the 90prime camera on the Steward Observatory Bok 90 inch telescope, and the Array Camera on the U.S. Naval Observatory, Flagstaff Station, 1.3 m telescope. The catalog covers 1098 square degrees to r = 22.0, an additional 1521 square degrees to r = 20.9, plus a further 488 square degrees of lesser quality data. Statistical errors in the proper motions range from 5 mas year{sup −1} at the bright end to 15 mas year{sup −1} at the faint end, for a typical epoch difference of six years. Systematic errors are estimated to be roughly 1 mas year{sup −1} for the Array Camera data, and as much as 2–4 mas year{sup −1} for the 90prime data (though typically less). The catalog also includes a second epoch of r band photometry.

  13. Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. V. Final Measurement for Fornax

    Science.gov (United States)

    Piatek, Slawomir; Pryor, Carlton; Bristow, Paul; Olszewski, Edward W.; Harris, Hugh C.; Mateo, Mario; Minniti, Dante; Tinney, Christopher G.

    2007-03-01

    The measured proper motion of Fornax, expressed in the equatorial coordinate system, is (μα,μδ)=(47.6+/-4.6,-36.0+/-4.1) mas century-1. This proper motion is a weighted mean of four independent measurements for three distinct fields. Each measurement uses a quasi-stellar object as a reference point. Removing the contribution of the motion of the Sun and of the local standard of rest to the measured proper motion produces a Galactic rest-frame proper motion of (μGrfα,μGrfδ)=(24.4+/-4.6,-14.3+/-4.1) mas century-1. The implied space velocity with respect to the Galactic center has a radial component of Vr=-31.8+/-1.7 km s-1 and a tangential component of Vt=196+/-29 km s-1. Integrating the motion of Fornax in a realistic potential for the Milky Way produces orbital elements. The perigalacticon and apogalacticon are 118 (66, 137) and 152 (144, 242) kpc, respectively, where the values in the parentheses represent the 95% confidence intervals derived from Monte Carlo experiments. The eccentricity of the orbit is 0.13 (0.11, 0.38), and the orbital period is 3.2 (2.5, 4.6) Gyr. The orbit is retrograde and inclined by 101° (94°, 107°) to the Galactic plane. Fornax could be a member of a proposed ``stream'' of galaxies and globular clusters; however, the membership of another proposed galaxy in the stream, Sculptor, has been previously ruled out. Fornax is in the Kroupa-Theis-Boily plane, which contains 11 of the Galactic satellite galaxies, but its orbit will take it out of that plane. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  14. Constraining the radio jet proper motion of the high-redshift quasar J2134-0419 at z = 4.3

    Science.gov (United States)

    Perger, Krisztina; Frey, Sándor; Gabányi, Krisztina É.; An, Tao; Britzen, Silke; Cao, Hong-Min; Cseh, Dávid; Dennett-Thorpe, Jane; Gurvits, Leonid I.; Hong, Xiao-Yu; Hook, Isobel M.; Paragi, Zsolt; Schilizzi, Richard T.; Yang, Jun; Zhang, Yingkang

    2018-06-01

    To date, PMN J2134-0419 (at a redshift z = 4.33) is the second most distant quasar known with a milliarcsecond-scale morphology permitting direct estimates of the jet proper motion. Based on two-epoch observations, we constrained its radio jet proper motion using the very long baseline interferometry (VLBI) technique. The observations were conducted with the European VLBI Network (EVN) at 5 GHz on 1999 November 26 and 2015 October 6. We imaged the central 10-pc scale radio jet emission and modelled its brightness distribution. By identifying a jet component at both epochs separated by 15.86 yr, a proper motion of μ = 0.035 ± 0.023 mas yr-1 is found. It corresponds to an apparent superluminal speed of βa = 4.1 ± 2.7 c. Relativistic beaming at both epochs suggests that the jet viewing angle with respect to the line of sight is smaller than 20°, with a minimum bulk Lorentz factor Γ = 4.3. The small value of the proper motion is in good agreement with the expectations from the cosmological interpretation of the redshift and the current cosmological model. Additionally we analysed archival Very Large Array observations of J2143-0419 and found indication of a bent jet extending to ˜30 kpc.

  15. The VMC survey. XXVIII. Improved measurements of the proper motion of the Galactic globular cluster 47 Tucanae

    Science.gov (United States)

    Niederhofer, Florian; Cioni, Maria-Rosa L.; Rubele, Stefano; Schmidt, Thomas; Bekki, Kenji; de Grijs, Richard; Emerson, Jim; Ivanov, Valentin D.; Oliveira, Joana M.; Petr-Gotzens, Monika G.; Ripepi, Vincenzo; Sun, Ning-Chen; van Loon, Jacco Th.

    2018-05-01

    We use deep multi-epoch point-spread function (PSF) photometry taken with the Visible and Infrared Survey Telescope for Astronomy (VISTA) to measure and analyze the proper motions of stars within the Galactic globular cluster 47 Tucanae (47 Tuc, NGC 104). The observations are part of the ongoing near-infrared VISTA survey of the Magellanic Cloud system (VMC). The data analyzed in this study correspond to one VMC tile, which covers a total sky area of 1.77 deg2. Absolute proper motions with respect to 9070 background galaxies are calculated from a linear regression model applied to the positions of stars in 11 epochs in the Ks filter. The data extend over a total time baseline of about 17 months. We found an overall median proper motion of the stars within 47 Tuc of (μαcos(δ), μδ) = (+5.89 ± 0.02 (statistical) ± 0.13 (systematic), -2.14 ± 0.02 (statistical) ± 0.08 (systematic)) mas yr-1, based on the measurements of 35 000 individual sources between 5' and 42' from the cluster center. We compared our result to the proper motions from the newest US Naval Observatory CCD Astrograph Catalog (UCAC5), which includes data from the Gaia data release 1. Selecting cluster members ( 2700 stars), we found a median proper motion of (μαcos(δ), μδ) = (+5.30 ± 0.03 (statistical) ± 0.70 (systematic), -2.70 ± 0.03 (statistical) ± 0.70 (systematic)) mas yr-1. Comparing the results with measurements in the literature, we found that the values derived from the VMC data are consistent with the UCAC5 result, and are close to measurements obtained using the Hubble Space Telescope. We combined our proper motion results with radial velocity measurements from the literature and reconstructed the orbit of 47 Tuc, finding that the cluster is on an orbit with a low ellipticity and is confined within the inner 7.5 kpc of the Galaxy. We show that the use of an increased time baseline in combination with PSF-determined stellar centroids in crowded regions significantly improves

  16. VizieR Online Data Catalog: Velocity and proper motion of OB associations (Melnik+, 2009)

    Science.gov (United States)

    Melnik, A. M.; Dambis, A. K.

    2009-11-01

    For every OB-association from the list by Blaha and Humphreys (1989AJ.....98.1598B) we give the mean galactic coordinates l and b, the mean heliocentric distance r, median line-of-sight velocity Vr, the dispersion of line-of-sight velocities dvr, and number of stars with known line-of-sight velocity nvr. The line-of-sight velocities were taken from the catalog by Barbier-Brossat and Figon (1999, Cat. ). We used only the velocities measured with errors of less than 10km/s which corresponds to the quality estimations A, B, and C. We also present median proper motions of OB-associations along l- and b- coordinates, mul and mub. The data obtained for the old reduction (1997, Cat. ) are denoted by the subscript 1, whereas those based on the reduction by van Leewen (2008, Cat. ) are marked by the subscript 2. For each OB association we represent the dispersions of proper motions, dml and dmb, as well as a number of stars nmu with known proper motion. The last column shows the total number of stars with known photometric measurements, Nt, used for determination of the distances for OB-associations. The distances r correspond to the short distance scale for classical Cepheids. They are equal to the distances from the catalog by Blaha and Humphreys (1989AJ.....98.1598B), rBH, multiplied by a factor of 0.8, r=0.8*rBH. (1 data file).

  17. A SUBSTELLAR COMMON PROPER-MOTION COMPANION TO THE PLEIAD H II 1348

    International Nuclear Information System (INIS)

    Geißler, Kerstin; Metchev, Stanimir A.; Pham, Alfonse; Larkin, James E.; McElwain, Michael; Hillenbrand, Lynne A.

    2012-01-01

    We announce the identification of a proper-motion companion to the star H II 1348, a K5 V member of the Pleiades open cluster. The existence of a faint point source 1.''1 away from H II 1348 was previously known from adaptive optics imaging by Bouvier et al. However, because of a high likelihood of background star contamination and in the absence of follow-up astrometry, Bouvier et al. tentatively concluded that the candidate companion was not physically associated with H II 1348. We establish the proper-motion association of the pair from adaptive optics imaging with the Palomar 5 m telescope. Adaptive optics spectroscopy with the integral field spectrograph OSIRIS on the Keck 10 m telescope reveals that the companion has a spectral type of M8 ± 1. According to substellar evolution models, the M8 spectral type resides within the substellar mass regime at the age of the Pleiades. The primary itself is a known double-lined spectroscopic binary, which makes the resolved companion, H II 1348B, the least massive and widest component of this hierarchical triple system and the first substellar companion to a stellar primary in the Pleiades.

  18. A method for determining the radius of an open cluster from stellar proper motions

    Science.gov (United States)

    Sánchez, Néstor; Alfaro, Emilio J.; López-Martínez, Fátima

    2018-04-01

    We propose a method for calculating the radius of an open cluster in an objective way from an astrometric catalogue containing, at least, positions and proper motions. It uses the minimum spanning tree in the proper motion space to discriminate cluster stars from field stars and it quantifies the strength of the cluster-field separation by means of a statistical parameter defined for the first time in this paper. This is done for a range of different sampling radii from where the cluster radius is obtained as the size at which the best cluster-field separation is achieved. The novelty of this strategy is that the cluster radius is obtained independently of how its stars are spatially distributed. We test the reliability and robustness of the method with both simulated and real data from a well-studied open cluster (NGC 188), and apply it to UCAC4 data for five other open clusters with different catalogued radius values. NGC 188, NGC 1647, NGC 6603, and Ruprecht 155 yielded unambiguous radius values of 15.2 ± 1.8, 29.4 ± 3.4, 4.2 ± 1.7, and 7.0 ± 0.3 arcmin, respectively. ASCC 19 and Collinder 471 showed more than one possible solution, but it is not possible to know whether this is due to the involved uncertainties or due to the presence of complex patterns in their proper motion distributions, something that could be inherent to the physical object or due to the way in which the catalogue was sampled.

  19. The SUPERBLINK catalog of stars with large proper motions, with enhancements from the first GAIA release.

    Science.gov (United States)

    Lepine, Sebastien

    2018-01-01

    The SUPERBLINK survey of stars with proper motion larger than 40 mas/yr is now complete for the entire sky down to magnitude V=20. The SUPERBLINK catalog provides astrometric and photometric data for a little over 2.7 million individual stars, and identifies their counterparts in a variety of large catalogs including ROSAT in the X-ray, GALEX in the ultraviolet, GAIA and SDSS in the optical, and 2MASS and WISE in the infrared. The addition of GAIA data notably yields proper motions to an accuracy of ~2mas/yr for 94% of the entries. Parallaxes with accuracies better than 10% are also now available for about 155,000 of these stars. Besides from identifying local populations of low-mass stars and white dwarfs, the catalog nows begins to map out with some detail the distribution in velocity space of various local stellar populations, including young M dwarfs and old metal-poor M subdwarfs. The catalog also allows one to search for common proper motion pairs, and other kinematic groups like nearby cluster members, moving group members, and local streams. This demonstrates the potential for nearby star research as more complete data becomes available from the GAIA mission.

  20. Motion of Charged Particles near Magnetic Field Discontinuities

    International Nuclear Information System (INIS)

    Dodin, I.Y.; Fisch, N.J.

    2000-01-01

    The motion of charged particles in slowly changing magnetic fields exhibits adiabatic invariance even in the presence of abrupt magnetic discontinuities. Particles near discontinuities in magnetic fields, what we call ''boundary particles'', are constrained to remain near an arbitrarily fractured boundary even as the particle drifts along the discontinuity. A new adiabatic invariant applies to the motion of these particles

  1. Catalogue of Positions and Proper Motions of Stars in the Vicinity of Open Clusters

    Directory of Open Access Journals (Sweden)

    Protsyuk, Yu.I.

    2017-01-01

    Full Text Available In the Research Institute Mykolaiv Astronomical Observatory (MAO the catalogue of position and proper motions of stars in the 544 square areas of nearly (1×1°around the Galactic open clusters was created using photographic and CCD observations. 293 plates of (5×5°obtained with the MAO Zonal Astrograph (D=116 mm, F=2040 mm in 1962-1993 and more than 20 thousands CCD frames (0.7×0.7° obtained with KT-50 telescope (D=500 mm, F=3000 mm in 2011-2015 were used. Almost 270 thousands FITS files from the IVOA image archives with observational epoch from 1953 to 2010 were downloaded and processed. The created catalogue contains more than 2.3 million stars (7.5-18.5m in the ICRS system with the accuracy of positions on both coordinates ranged from 0.02" to 0.05". Inner accuracy of proper motions is ~0.004"/year.

  2. Catalogue of positions and proper motions of stars in the vicinity of open clusters

    Science.gov (United States)

    Protsyuk, Yu. I.; Kovalchuk, O. M.; Mazhaev, O. E.

    2017-02-01

    A catalog of positions and proper motions of stars in 544 square areas of nearly (1 × 1)° around the Galactic open clusters has been created using photographic and CCD observations, at Research Institute "Mykolaiv Astronomical Observatory" (RI "MAO"). To this end, 293 plates of (5 × 5)° obtained with the MAO Zonal Astrograph (D=116 mm, F=2040 mm) in 1962-1993 and more than 20 thousand CCD frames (0.7 × 0.7)° obtained with KT-50 telescope (D=500 mm, F=3000 mm) in 2011-2015 have been used. Almost 270 thousand FITS files from the IVOA image archives with observational epoch from 1953 to 2010 have been downloaded and processed. The created catalogue contains more than 2.3 million stars having a magnitude of (7.5-18.5)m in the ICRS system, with accuracy of positions for both coordinates ranging from 0.02" to 0.05". Internal accuracy of proper motions is estimated as ~0.004"/year.

  3. EROS 2 proper motion survey a field brown dwarf and an L dwarf companion to LHS 102

    CERN Document Server

    Goldman, B; Forveille, T; Afonso, C; Alard, C; Albert, J N; Andersen, J; Ansari, R; Aubourg, E; Bareyre, P; Bauer, F; Beaulieu, J P; Borsenberger, J; Bouquet, A; Char, S; Charlot, X; Couchot, F; Coutures, C; Derue, F; Ferlet, R; Fouqué, P; Glicenstein, J F; Gould, A; Graff, D S; Gros, M H; Haïssinski, J; Hamilton, J C; Hardin, D P; De Kat, J; Kim, A; Lasserre, T; Lesquoy, E; Loup, C; Magneville, C; Mansoux, B; Marquette, J B; Martín, E L; Maurice, E; Milshtein, A I; Moniez, M; Palanque-Delabrouille, Nathalie; Perdereau, O; Prévôt, L; Regnault, N; Rich, J; Spiro, Michel; Vidal-Madjar, A; Virgoux, L; Zylberajch, S

    1999-01-01

    We report the discovery of two L dwarfs (the new spectral class defined for dwarfs cooler than the M type) in a two-epoch CCD proper motion survey of 413 square degrees, complemented by infrared photometry from DENIS. One of them has a strong lithium line and is therefore a brown dwarf. The other is a common proper motion companion to the mid-M dwarf LHS 102 (GJ 1001), which has a well determined trigonometric parallax. LHS 102B is thus the coolest L dwarf of known distance and luminosity. Its infrared absolute photometry are very well reproduced by the Allard et al DUSTY models.

  4. Predicted space motions for hypervelocity and runaway stars: proper motions and radial velocities for the Gaia Era

    Energy Technology Data Exchange (ETDEWEB)

    Kenyon, Scott J.; Brown, Warren R.; Geller, Margaret J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Bromley, Benjamin C., E-mail: skenyon@cfa.harvard.edu, E-mail: wbrown@cfa.harvard.edu, E-mail: mgeller@cfa.harvard.edu, E-mail: bromley@physics.utah.edu [Department of Physics, University of Utah, 115 S 1400 E, Rm 201, Salt Lake City, UT 84112 (United States)

    2014-10-01

    We predict the distinctive three-dimensional space motions of hypervelocity stars (HVSs) and runaway stars moving in a realistic Galactic potential. For nearby stars with distances less than 10 kpc, unbound stars are rare; proper motions alone rarely isolate bound HVSs and runaways from indigenous halo stars. At large distances of 20-100 kpc, unbound HVSs are much more common than runaways; radial velocities easily distinguish both from indigenous halo stars. Comparisons of the predictions with existing observations are encouraging. Although the models fail to match observations of solar-type HVS candidates from SEGUE, they agree well with data for B-type HVS and runaways from other surveys. Complete samples of g ≲ 20 stars with Gaia should provide clear tests of formation models for HVSs and runaways and will enable accurate probes of the shape of the Galactic potential.

  5. VizieR Online Data Catalog: Velocities and proper motions of Galactic Cepheids (Mel'nik+, 2015)

    Science.gov (United States)

    Mel'Nik, A. M.; Rautiainen, P.; Berdnikov, L. N.; Dambis, A. K.; Rastorguev, A. S.

    2015-01-01

    For every classical Cepheid we give its designation in the General Catalog of Variable Stars (GCVS) (Samus at al., 2007, Cat. B/gcvs) or in the All Sky Automated Survey (ASAS) (Pojmanski 2002, II/264), its type (see GCVS description), fundamental period PF, intensity-mean V-band magnitude , J2000 equatorial coordinates, Galactic coordinates l and b, and heliocentric distance r. Table 1 also gives the Cepheid line-of-sight velocities Vr (the so-called γ-velocities), their uncertainties e_Vr and the references (1-6) to the sources from which they are taken. The proper motions of Cepheids were adopted from the new reduction of Hipparcos data (ESA 1997, Cat. I/239) by van Leeuwen (2007, Cat. I/311). Table 1 presents proper motions pml and pmb, their uncertainties e_pml and e_pmb and the corresponding Hipparcos catalog number HIP. (1 data file).

  6. Molecular structure and motion in zero field magnetic resonance

    International Nuclear Information System (INIS)

    Jarvie, T.P.

    1989-10-01

    Zero field magnetic resonance is well suited for the determination of molecular structure and the study of motion in disordered materials. Experiments performed in zero applied magnetic field avoid the anisotropic broadening in high field nuclear magnetic resonance (NMR) experiments. As a result, molecular structure and subtle effects of motion are more readily observed

  7. Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. III. Measurement for Ursa Minor

    Science.gov (United States)

    Piatek, Slawomir; Pryor, Carlton; Bristow, Paul; Olszewski, Edward W.; Harris, Hugh C.; Mateo, Mario; Minniti, Dante; Tinney, Christopher G.

    2005-07-01

    This article presents a measurement of the proper motion of the Ursa Minor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope in two distinct fields. Each field contains a quasi-stellar object that serves as the ``reference point.'' The measured proper motion for Ursa Minor, expressed in the equatorial coordinate system, is (μα,μδ)=(-50+/-17,22+/-16) mas century-1. Removing the contributions of the solar motion and the motion of the local standard of rest yields the proper motion in the Galactic rest frame: (μGrfα,μGrfδ)=(-8+/-17,38+/-16) mas century-1. The implied space velocity with respect to the Galactic center has a radial component of Vr=-75+/-44 km s-1 and a tangential component of Vt=144+/-50 km s-1. Integrating the motion of Ursa Minor in a realistic potential for the Milky Way produces orbital elements. The perigalacticon and apogalacticon are 40 (10, 76) and 89 (78, 160) kpc, respectively, where the values in the parentheses represent the 95% confidence intervals derived from Monte Carlo experiments. The eccentricity of the orbit is 0.39 (0.09, 0.79), and the orbital period is 1.5 (1.1, 2.7) Gyr. The orbit is retrograde and inclined by 124° (94°, 136°) to the Galactic plane. Ursa Minor is not a likely member of a proposed stream of galaxies on similar orbits around the Milky Way, nor is the plane of its orbit coincident with a recently proposed planar alignment of galaxies around the Milky Way. Comparing the orbits of Ursa Minor and Carina shows no reason for the different star formation histories of these two galaxies. Ursa Minor must contain dark matter to have a high probability of having survived disruption by the Galactic tidal force until the present. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  8. Investigation of wire motion in superconducting magnets

    International Nuclear Information System (INIS)

    Ogitsu, T.; Tsuchiya, K.; Devred, A.

    1990-09-01

    The large Lorentz forces occuring during the excitation of superconducting magnets can provoke sudden motions of wire, which eventually release enough energy to trigger a quench. These wire motions are accompanied by two electromagnetic effects: an induced emf along the moved wire, and a local change in flux caused by the minute dislocation of current. Both effects cause spikes in the coil voltage. Voltage data recorded during the excitation of a superconducting quadrupole magnet which early exhibit such events are here reported. Interpretations of the voltage spikes in terms of energy release are also presented, leading to insights on the spectrum of the disturbances which occur in real magnets. 15 refs

  9. Hybrid magnetic mechanism for active locomotion based on inchworm motion

    International Nuclear Information System (INIS)

    Kim, Sung Hoon; Hashi, Shuichiro; Ishiyama, Kazushi

    2013-01-01

    Magnetic robots have been studied in the past. Insect-type micro-robots are used in various biomedical applications; researchers have developed inchworm micro-robots for endoscopic use. A biological inchworm has a looping locomotion gait. However, most inchworm micro-robots depend on a general bending, or bellows, motion. In this paper, we introduce a new robotic mechanism using magnetic force and torque control in a rotating magnetic field for a looping gait. The proposed robot is controlled by the magnetic torque, attractive force, and body mechanisms (two stoppers, flexible body, and different frictional legs). The magnetic torque generates a general bending motion. In addition, the attractive force and body mechanisms produce the robot’s looping motion within a rotating magnetic field and without the use of an algorithm for field control. We verified the device’s performance and analyzed the motion through simulations and various experiments. The robot mechanism can be applied to active locomotion for various medical robots, such as wireless endoscopes. (technical note)

  10. AN HST PROPER-MOTION STUDY OF THE LARGE-SCALE JET OF 3C273

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Eileen T.; Georganopoulos, Markos [University of Maryland Baltimore County, Baltimore, MD 21250 (United States); Sparks, William B. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Anderson, Jay; Marel, Roeland van der; Biretta, John; Chiaberge, Marco; Norman, Colin [Space Telescope Science Institute, Baltimore, MD 21210 (United States); Tony Sohn, Sangmo [Johns Hopkins University, Baltimore, MD 21210 (United States); Perlman, Eric, E-mail: meyer@stsci.edu [Florida Institute of Technology, Melbourne, FL 32901 (United States)

    2016-02-20

    The radio galaxy 3C 273 hosts one of the nearest and best-studied powerful quasar jets. Having been imaged repeatedly by the Hubble Space Telescope (HST) over the past twenty years, it was chosen for an HST program to measure proper motions in the kiloparsec-scale resolved jets of nearby radio-loud active galaxies. The jet in 3C 273 is highly relativistic on sub-parsec scales, with apparent proper motions up to 15c observed by very long baseline interferometry. In contrast, we find that the kiloparsec-scale knots are compatible with being stationary, with a mean speed of −0.2 ± 0.5c over the whole jet. Assuming the knots are packets of moving plasma, an upper limit of 1c implies a bulk Lorentz factor Γ < 2.9. This suggests that the jet has either decelerated significantly by the time it reaches the kiloparsec scale, or that the knots in the jet are standing shock features. The second scenario is incompatible with the inverse Compton off the Cosmic Microwave Background (IC/CMB) model for the X-ray emission of these knots, which requires the knots to be in motion, but IC/CMB is also disfavored in the first scenario due to energetic considerations, in agreement with the recent finding of Meyer and Georganopoulos which ruled out the IC/CMB model for the X-ray emission of 3C 273 via gamma-ray upper limits.

  11. COMMON PROPER-MOTION WIDE WHITE DWARF BINARIES SELECTED FROM THE SLOAN DIGITAL SKY SURVEY

    International Nuclear Information System (INIS)

    Andrews, Jeff J.; Agüeros, Marcel A.; Belczynski, Krzysztof; Dhital, Saurav; Kleinman, S. J.; West, Andrew A.

    2012-01-01

    Wide binaries made up of two white dwarfs (WDs) receive far less attention than their tight counterparts. However, our tests using the binary population synthesis code StarTrack indicate that, for any set of reasonable initial conditions, there exists a significant observable population of double white dwarfs (WDWDs) with orbital separations of 10 2 -10 5 AU. We adapt the technique of Dhital et al. to search for candidate common proper-motion WD companions separated by 12,000 spectroscopically confirmed hydrogen-atmosphere WDs recently identified in the Sloan Digital Sky Survey. Using two techniques to separate random alignments from high-confidence pairs, we find nine new high-probability wide WDWDs and confirm three previously identified candidate wide WDWDs. This brings the number of known wide WDWDs to 45; our new pairs are a significant addition to the sample, especially at small proper motions ( –1 ) and large angular separations (>10''). Spectroscopic follow-up and an extension of this method to a larger, photometrically selected set of SDSS WDs may eventually produce a large enough dataset for WDWDs to realize their full potential as testbeds for theories of stellar evolution.

  12. Mapping stellar kinematics across the Galactic bar : HST measurements of proper motions in 35 fields

    NARCIS (Netherlands)

    Kozlowski, S.; Wozniak, P. R.; Mao, S.; Smith, M. C.; Sumi, T.; Vestrand, W. T.; Wyrzykowski, L.

    2006-01-01

    We present a proper motion mini-survey of 35 fields in the vicinity of Baade window, (l, b) = (1 degrees, -4 degrees), sampling roughly a 5 x 2.5-deg(2) region of the Galactic bar. Our second epoch observations collected with the Advanced Camera for Surveys/High Resolution Channel instrument onboard

  13. A SEARCH FOR HIGH PROPER MOTION T DWARFS WITH Pan-STARRS1 + 2MASS + WISE

    International Nuclear Information System (INIS)

    Liu, Michael C.; Deacon, Niall R.; Magnier, Eugene A.; Aller, Kimberly M.; Bowler, Brendan P.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Morgan, J. S.; Tonry, J. L.; Wainscoat, R. J.; Dupuy, Trent J.; Redstone, Joshua; Goldman, Bertrand; Price, P. A.

    2011-01-01

    We have searched ∼8200 deg 2 for high proper motion (∼0.''5-2.''7 year -1 ) T dwarfs by combining first-epoch data from the Pan-STARRS1 (PS1) 3π Survey, the Two Micron All Sky Survey (2MASS) All-Sky Point Source Catalog, and the WISE Preliminary Data Release. We identified two high proper motion objects with the very red (W1 - W2) colors characteristic of T dwarfs, one being the known T7.5 dwarf GJ 570D. Near-IR spectroscopy of the other object (PSO J043.5395+02.3995 ≡ WISEP J025409.45+022359.1) reveals a spectral type of T8, leading to a photometric distance of 7.2 ± 0.7 pc. The 2.''56 year -1 proper motion of PSO J043.5+02 is the second highest among field T dwarfs, corresponding to a tangential velocity of 87 ± 8 km s -1 . According to the Besancon galaxy model, this velocity indicates that its galactic membership is probably in the thin disk, with the thick disk an unlikely possibility. Such membership is in accord with the near-IR spectrum, which points to a surface gravity (age) and metallicity typical of the field population. We combine 2MASS, Sloan Digital Sky Survey, WISE, and PS1 astrometry to derive a preliminary parallax of 171 ± 45 mas (5.8 +2.0 -1.2 pc), the first such measurement using PS1 data. The proximity and brightness of PSO J043.5+02 will facilitate future characterization of its atmosphere, variability, multiplicity, distance, and kinematics. The modest number of candidates from our search suggests that the immediate (∼10 pc) solar neighborhood does not contain a large reservoir of undiscovered T dwarfs earlier than about T8.

  14. Sunspot proper motions in active region NOAA 2372 and its flare activity during SMY period of 1980 April 4-13

    International Nuclear Information System (INIS)

    Ambastha, A.; Bhatnagar, A.

    1988-01-01

    Solar Active Region NOAA 2372 was observed extensively by the Solar Maximum Mission (SMM) satellite and several ground-based observatories during 1980 April 4-13 in the Solar Maximum Year. After its birth around April 4, it underwent a rapid growth and produced a reported 84 flares in the course of its disc passage. In this paper, photospheric and chromospheric observations of this active region have been studied together with Marshall Space Flight Center magnetograms and X-ray data from HXIS aboard the SMM satellite. In particular, the relationship of the flare-productivity with sunspot proper motions and emergence of new regions of magnetic flux in the active region from its birth to its disappearance at the W-limb has been discussed. (author). 7 figures, 2 tables, 29 refs

  15. THE PPMXL CATALOG OF POSITIONS AND PROPER MOTIONS ON THE ICRS. COMBINING USNO-B1.0 AND THE TWO MICRON ALL SKY SURVEY (2MASS)

    International Nuclear Information System (INIS)

    Roeser, S.; Demleitner, M.; Schilbach, E.

    2010-01-01

    USNO-B1.0 and the Two Micron All Sky Survey (2MASS) are the most widely used all-sky surveys. However, 2MASS has no proper motions at all, and USNO-B1.0 published only relative, not absolute (i.e., on the International Celestial Reference Frame (ICRS), proper motions. We performed a new determination of mean positions and proper motions on the ICRS system by combining USNO-B1.0 and 2MASS astrometry. This catalog is called PPMXL (VO access to the catalog is possible via http://vo.uni-hd.de/ppmxl), and it aims to be completed from the brightest stars down to about V ∼ 20 all sky. PPMXL contains about 900 million objects, some 410 million with 2MASS photometry, and is the largest collection of ICRS proper motions at present. As representative for the ICRS, we chose PPMX. The recently released UCAC3 could not be used because we found plate-dependent distortions in its proper motion system north of -20 0 declination. UCAC3 served as an intermediate system for δ ≤ -20 0 . The resulting typical individual mean errors of the proper motions range from 4 mas yr -1 to more than 10 mas yr -1 depending on observational history. The mean errors of positions at epoch 2000.0 are 80-120 mas, if 2MASS astrometry could be used, 150-300 mas else. We also give correction tables to convert USNO-B1.0 observations of, e.g., minor planets to the ICRS system.

  16. Approximate Integrals of rf-driven Particle Motion in Magnetic Field

    International Nuclear Information System (INIS)

    Dodin, I.Y.; Fisch, N.J.

    2004-01-01

    For a particle moving in nonuniform magnetic field under the action of an rf wave, ponderomotive effects result from rf-driven oscillations nonlinearly coupled with Larmor rotation. Using Lagrangian and Hamiltonian formalism, we show how, despite this coupling, two independent integrals of the particle motion are approximately conserved. Those are the magnetic moment of free Larmor rotation and the quasi-energy of the guiding center motion parallel to the magnetic field. Under the assumption of non-resonant interaction of the particle with the rf field, these integrals represent adiabatic invariants of the particle motion

  17. The Ultimate Catalog of Omega Centauri: 15-BAND Photometry and Proper Motions

    Science.gov (United States)

    Anderson, Jay

    2011-10-01

    We propose to construct the most comprehensive catalog of photometry and proper motions ever assembled for a globular cluster {GC}. The core of Omega Centauri has been imaged nearly 500 times through WFC3's UVIS and IR channels for the purposes of detector calibration. There exist 30 exposures through each of 15 filters, stretching uniformly from F225W in the UV to F160W in the infrared. Furthermore, the 8-year baseline between this data and a 2002 ACS survey will more than double the accuracy and triple the number of well-measured stars compared to our previous groundbreaking effort. This totally unprecedented complete spectral coverage for over 300,000 stars, from the red-giant branch {RGB} down to the white dwarfs {WDs}, provides the best chance yet to understand the multiple-population phenomenon in any GC. A preliminary analysis of the color-magnitude diagrams in different bands already allows us to identify more than 10 distinct sequences.We will make the full catalog of 15-band photometry and proper motions available to the community within 6 months of starting this project. We will then be the first to exploit this tremendous resource. The science we will address includes: {1} identifying all the sequences and tying them together, from the main sequence up to the RGB;{2} continuing the search for a central massive object; {3} examination of the WD sequence for any manifestations of multiple-populations; and{4} searching for cataclysmic variables and He WDs.

  18. Magnetic distortion in motion labs, implications for validating inertial magnetic sensors

    NARCIS (Netherlands)

    de Vries, W.H.; Veeger, H.E.J.; Baten, C.T.M.; Helm, F.C.

    2009-01-01

    Background: Ambulatory 3D orientation estimation with Inertial Magnetic Sensor Units (IMU's) use the earth magnetic field. The magnitude of distortion in orientation in a standard equipped motion lab and its effect on the accuracy of the orientation estimation with IMU's is addressed. Methods:

  19. Magnetic distortion in motion labs, implications for validating inertial magnetic sensors.

    NARCIS (Netherlands)

    Vries, W.H. de; Veeger, H.E.; Baten, C.T.; Helm, F.C.T. van der

    2009-01-01

    BACKGROUND: Ambulatory 3D orientation estimation with Inertial Magnetic Sensor Units (IMU's) use the earth magnetic field. The magnitude of distortion in orientation in a standard equipped motion lab and its effect on the accuracy of the orientation estimation with IMU's is addressed. METHODS:

  20. COMMON PROPER-MOTION WIDE WHITE DWARF BINARIES SELECTED FROM THE SLOAN DIGITAL SKY SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Jeff J.; Agueeros, Marcel A. [Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Belczynski, Krzysztof [Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warsaw (Poland); Dhital, Saurav [Department of Physics and Astronomy, Vanderbilt University, 6301 Stevenson Center, Nashville, TN 37235 (United States); Kleinman, S. J. [Gemini Observatory, Northern Operations Center, Hilo, HI 96720 (United States); West, Andrew A. [Department of Astronomy, Boston University, 725 Commonwealth Ave, Boston, MA 02215 (United States)

    2012-10-01

    Wide binaries made up of two white dwarfs (WDs) receive far less attention than their tight counterparts. However, our tests using the binary population synthesis code StarTrack indicate that, for any set of reasonable initial conditions, there exists a significant observable population of double white dwarfs (WDWDs) with orbital separations of 10{sup 2}-10{sup 5} AU. We adapt the technique of Dhital et al. to search for candidate common proper-motion WD companions separated by <10' around the >12,000 spectroscopically confirmed hydrogen-atmosphere WDs recently identified in the Sloan Digital Sky Survey. Using two techniques to separate random alignments from high-confidence pairs, we find nine new high-probability wide WDWDs and confirm three previously identified candidate wide WDWDs. This brings the number of known wide WDWDs to 45; our new pairs are a significant addition to the sample, especially at small proper motions (<200 mas yr{sup -1}) and large angular separations (>10''). Spectroscopic follow-up and an extension of this method to a larger, photometrically selected set of SDSS WDs may eventually produce a large enough dataset for WDWDs to realize their full potential as testbeds for theories of stellar evolution.

  1. VizieR Online Data Catalog: WD+dMs from the SUPERBLINK proper motion survey (Skinner+, 2017)

    Science.gov (United States)

    Skinner, J. N.; Morgan, D. P.; West, A. A.; Lepine, S.; Thorstensen, J. R.

    2018-06-01

    To select for nearby WD+dMs, we used the SUPERBLINK proper motion survey (Lepine et al. 2002, J/AJ/124/1190; Lepine & Shara 2005, Cat. I/298), an ongoing all-sky survey that identifies and characterizes stars with proper motions μ>40 mas/yr. For this study, we used the 2011 July version of SUPERBLINK, which listed 2270481 stars, and was estimated to be >90% complete to V=19.0. We selected WD+dMs based on a combination of V magnitudes derived from the DSS plates (see Lepine & Shara 2005, Cat. I/298), near-UV magnitudes from GALEX, and Ks magnitudes from 2MASS. Using the UV-optical-IR color selection outlined in Skinner et al. (2014AJ....148..115S), we selected targets for spectroscopic follow-up (see bottom panel of Figure 1). We acquired optical spectroscopy of 178 newly identified WD+dM candidates, with the Boller and Chivens CCD spectrograph (CCDS), using both the Hiltner 2.4 m and McGraw-Hill 1.3 m telescopes located at the MDM Observatory. (3 data files).

  2. Small-polaron formation and motion in magnetic semiconductors

    International Nuclear Information System (INIS)

    Emin, D.

    1979-01-01

    The fundamental physical processes associated with small-polaron formation are described with various magnetic semi-conductors being cited as examples. Attention is then directed toward the mechanisms of charge transfer and small-polaron hopping motion in magnetic semiconductors

  3. Arc Motion in an Obliquely Imposed Alternating Magnetic Field

    International Nuclear Information System (INIS)

    Akiho, R; Takeda, K; Sugimoto, M

    2012-01-01

    The arc motion is theoretically investigated under an alternating magnetic field imposed obliquely to the arc. The arc is known to oscillate on a 2-D plane when the alternating magnetic field is imposed perpendicularly to the arc. If the alternating magnetic field is imposed obliquely to the arc, then it is expected that the arc oscillates not on the 2-D plane but in a 3-D space. For this study, 3-D simulation was performed on the motion of the plasma gas under an alternating magnetic field crossing obliquely to the arc. It was also assumed that a stream line of the plasma gas represented the arc profile. The momentum equation for the plasma gas was solved together with the continuity equation. Governing parameters for the gas motion are θ (crossing angle), v 0 (initial velocity of the plasma gas), and λ. Parameter λ is defined as λ = (I a B 0 )/Q 0 . Numerical results are reported under different operating conditions such as magnetic flux densities and the angles between the arc and the magnetic flux. If the crossing angle is larger than 4/π, the arc might be extinguished because of the drastic increase of the arc length.

  4. The first allwise proper motion discovery: Wisea J070720.50+170532.7

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Edward L.; Mace, Gregory; McLean, Ian S. [UCLA Astronomy, P.O. Box 951547, Los Angeles, CA 90095-1547 (United States); Kirkpatrick, J. Davy; Gelino, Christopher R.; Fajardo-Acosta, Sergio [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Eisenhardt, Peter R.; Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Skrutskie, M. F.; Oza, Apurva; Nelson, M. J. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Cushing, Michael C. [Department of Physics and Astronomy, University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606-3328 (United States); Reid, I. Neill [STScI, Baltimore, MD 21218 (United States); Fumagalli, Michele [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); Burgasser, Adam J., E-mail: wright@astro.ucla.edu [University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States)

    2014-03-01

    While quality checking a new motion-aware co-addition of all 12.5 months of Wide-field Infrared Survey Explorer (WISE) data, we found that the source WISE J070720.48+170533.0 moved 0.''9 in six months. Backtracking this motion allowed us to identify this source as 2MASS J07071961+1705464, with several entries in the USNO B catalog. An astrometric fit to these archival data gives a proper motion of μ = 1793 ± 2 mas yr{sup –1} and a parallax of piv = 35 ± 42 mas. Photometry from WISE, 2MASS, and the POSS can be fit reasonably well by a blackbody with T = 3658 K and an angular radius of 4.36 × 10{sup –11} radians. No clear evidence of H{sub 2} collision-induced absorption is seen in the near-infrared. An optical spectrum shows broad deep CaH bands at 638 and 690 nm, broad deep Na D at 598.2 nm, and weak or absent TiO, indicating that this source is an ultra-subdwarf M star with a radial velocity v {sub rad} ≈ –21 ± 18 km s{sup –1} relative to the Sun. Given its apparent magnitude, the distance is about 39 ± 9 pc and the tangential velocity is probably ≈330 km s{sup –1}, but a more precise parallax is needed to be certain.

  5. Effect of Dimension and Shape of Magnet on the Performance AC Generator with Translation Motion

    Science.gov (United States)

    Indriani, A.; Dimas, S.; Hendra

    2018-02-01

    The development of power plants using the renewable energy sources is very rapid. Renewable energy sources used solar energy, wind energy, ocean wave energy and other energy. All of these renewable energy sources require a processing device or a change of motion system to become electrical energy. One processing device is a generator which have work principle of converting motion (mechanical) energy into electrical energy with rotary shaft, blade and other motion components. Generator consists of several types of rotation motion and linear motion (translational). The generator have components such as rotor, stator and anchor. In the rotor and stator having magnet and winding coil as an electric generating part of the electric motion force. Working principle of AC generator with linear motion (translation) also apply the principle of Faraday that is using magnetic induction which change iron magnet to produce magnetic flux. Magnetic flux is captured by the stator to be converted into electrical energy. Linear motion generators consist of linear induction machine, wound synchronous machine field, and permanent magnet synchronous [1]. Performance of synchronous generator of translation motion is influenced by magnet type, magnetic shape, coil winding, magnetic and coil spacing and others. In this paper focus on the neodymium magnet with varying shapes, number of coil windings and gap of magnetic distances. This generator work by using pneumatic mechanism (PLTGL) for power plants system. Result testing of performance AC generator translation motion obtained that maximum voltage, current and power are 63 Volt for diameter winding coil 0.15 mm, number of winding coil 13000 and distance of magnet 20 mm. For effect shape of magnet, maximum voltage happen on rectangle magnet 30x20x5 mm with 4.64 Volt. Voltage and power on effect of diameter winding coil is 14.63 V and 17.82 W at the diameter winding coil 0.7 and number of winding coil is 1260 with the distance of magnet 25

  6. On the Unsteady-Motion Theory of Magnetic Forces for Maglev

    Science.gov (United States)

    1993-11-01

    DivisionEnergy Technology Division Forces for Maglev Energy Technology DivisionEnergy Technology Division by S. S. Chen, S. Zhu, and Y. Cai APQ 4 袲...On the Unsteady-Motion Theory of Magnetic Forces for Maglev by S. S. Chen, S. Zhu, and Y. Cai Energy Technology Division November 1993 Work supported...vi On The Unsteady-Motion Theory of Magnetic Forces for Maglev by S. S

  7. Insolubility of trapped particle motion in a magnetic dipole field

    International Nuclear Information System (INIS)

    Dragt, A.J.; Finn, J.M.

    1976-01-01

    Topological and numerical techniques are used to show that the problem of trapped charged particle motion in a magnetic dipole field is insoluble. Similar results hold for motion in the earth's magnetic field and are of interest for radiation belt phenomena. Pedagogical discussion is devoted to the subject of how it can happen that a classical mechanics problem is insoluble and in what sense. It is shown that the complete adiabatic magnetic moment series is divergent and that due to the existence of homoclinic points the solutions to the equations of motion are too complicated to be written in closed form. As a consequence, there is currently no rigorous theoretical explanation for the empirical success of adiabatic orbit theory, and a completely satisfactory mathematical justification will be far from easy

  8. HST Proper Motions of Distant Globular Clusters: Constraining the Formation & Mass of the Milky Way

    Science.gov (United States)

    Sohn, S. Tony; van der Marel, Roeland P.; Deason, Alis; Bellini, Andrea; Besla, Gurtina; Watkins, Laura

    2018-04-01

    Proper motions (PMs) are required to calculate accurate orbits of globular clusters (GCs) in the Milky Way (MW) halo. We present our HST program to create a PM database for 20 GCs at distances of R GC = 10-100 kpc. Targets are discussed along with PM measurement methods. We also describe how our PM results can be used for Gaia as an external check, and discuss the synergy between HST and Gaia as astrometric instruments in the coming years.

  9. Localized and Delocalized Motion of Colloidal Particles on a Magnetic Bubble Lattice

    International Nuclear Information System (INIS)

    Tierno, Pietro; Fischer, Thomas M.; Johansen, Tom H.

    2007-01-01

    We study the motion of paramagnetic colloidal particles placed above magnetic bubble domains of a uniaxial garnet film and driven through the lattice by external magnetic field modulation. An external tunable precessing field propels the particles either in localized orbits around the bubbles or in superdiffusive or ballistic motion through the bubble array. This motion results from the interplay between the driving rotating signal, the viscous drag force and the periodic magnetic energy landscape. We explain the transition in terms of the incommensurability between the transit frequency of the particle through a unit cell and the modulation frequency. Ballistic motion dynamically breaks the symmetry of the array and the phase locked particles follow one of the six crystal directions

  10. Quantifying the motion of magnetic particles in excised tissue: Effect of particle properties and applied magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, Sandip, E-mail: sandip.d.kulkarni@gmail.com [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); Ramaswamy, Bharath; Horton, Emily; Gangapuram, Sruthi [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); Nacev, Alek [Weinberg Medical Physics, LLC (United States); Depireux, Didier [The Institute for Systems Research, University of Maryland at College Park, MD 20742 (United States); Otomagnetics, LLC (United States); Shimoji, Mika [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); Otomagnetics, LLC (United States); Shapiro, Benjamin [Fischell Department of Bioengineering, University of Maryland at College Park, MD 20742 (United States); The Institute for Systems Research, University of Maryland at College Park, MD 20742 (United States); Otomagnetics, LLC (United States)

    2015-11-01

    This article presents a method to investigate how magnetic particle characteristics affect their motion inside tissues under the influence of an applied magnetic field. Particles are placed on top of freshly excised tissue samples, a calibrated magnetic field is applied by a magnet underneath each tissue sample, and we image and quantify particle penetration depth by quantitative metrics to assess how particle sizes, their surface coatings, and tissue resistance affect particle motion. Using this method, we tested available fluorescent particles from Chemicell of four sizes (100 nm, 300 nm, 500 nm, and 1 μm diameter) with four different coatings (starch, chitosan, lipid, and PEG/P) and quantified their motion through freshly excised rat liver, kidney, and brain tissues. In broad terms, we found that the applied magnetic field moved chitosan particles most effectively through all three tissue types (as compared to starch, lipid, and PEG/P coated particles). However, the relationship between particle properties and their resulting motion was found to be complex. Hence, it will likely require substantial further study to elucidate the nuances of transport mechanisms and to select and engineer optimal particle properties to enable the most effective transport through various tissue types under applied magnetic fields.

  11. THE SOLAR NEIGHBORHOOD. XXV. DISCOVERY OF NEW PROPER MOTION STARS WITH 0.''40 yr-1 > μ ≥ 0.''18 yr-1 BETWEEN DECLINATIONS -470 AND 000

    International Nuclear Information System (INIS)

    Boyd, Mark R.; Winters, Jennifer G.; Henry, Todd J.; Jao, Wei-Chun; Finch, Charlie T.; Subasavage, John P.; Hambly, Nigel C.

    2011-01-01

    We present 2817 new southern proper motion systems with 0.''40 yr -1 > μ ≥ 0.''18 yr -1 and declination between -47 0 and 00 0 . This is a continuation of the SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky. We use the same photometric relations as previous searches to provide distance estimates based on the assumption that the objects are single main-sequence stars. We find 79 new red dwarf systems predicted to be within 25 pc, including a few new components of previously known systems. Two systems-SCR 1731-2452 at 9.5 pc and SCR 1746-3214 at 9.9 pc-are anticipated to be within 10 pc. We also find 23 new white dwarf (WD) candidates with distance estimates of 15-66 pc, as well as 360 new red subdwarf candidates. With this search, we complete the SCR sweep of the southern sky for stars with μ ≥ 0.''18 yr -1 and R 59F ≤ 16.5, resulting in a total of 5042 objects in 4724 previously unreported proper motion systems. Here we provide selected comprehensive lists from our SCR proper motion search to date, including 152 red dwarf systems estimated to be within 25 pc (9 within 10 pc), 46 WDs (10 within 25 pc), and 598 subdwarf candidates. The results of this search suggest that there are more nearby systems to be found at fainter magnitudes and lower proper motion limits than those probed so far.

  12. Nuclear magnetic resonance method and apparatus for reducing motion artifacts

    International Nuclear Information System (INIS)

    Bailes, D.R.

    1988-01-01

    A nuclear magnetic resonance apparatus for imaging a region of a body in which part of the region is moving with a motion such that its displacement with respect to time is a nonmonotonic function during a time period over which a plurality of NMR data signals, which together define an image, are collected. The apparatus is described comprising: excitation means arranged to excite nuclear magnetic spins preferentially in the region; encoding means arranged to encode the magnetic spins; data collection means arranged to collect data signals representative of encoded magnetic spins; display means responsive to collected data signals to display an image of the region; measuring means arranged to produce an output indicative of the displacement of the moving part of the region; and control means for controlling the encoding means during the time period in dependence on the output of the measuring means so that data signals collected during the time period are collected in an order dependent on the motion such that motion artifacts are reduced

  13. VizieR Online Data Catalog: Gaia-PS1-SDSS (GPS1) proper motion catalog (Tian+, 2017)

    Science.gov (United States)

    Tian, H.-J.; Gupta, P.; Sesar, B.; Rix, H.-W.; Martin, N. F.; Liu, C.; Goldman, B.; Platais, I.; Kudritzki, R.-P.; Waters, C. Z.

    2018-02-01

    In order to construct proper motions, we analyze and model catalog positions from four different imaging surveys, as discussed below. Gaia DR1 is based on observations collected between 2014 July 25 and 2015 September 16. PS1 observations were collected between 2010 and 2014. The SDSS DR9 data used here were obtained in the years between 2000 and 2008. The images from 2MASS were taken between 1997 and 2001. (1 data file).

  14. Knowing Our Neighbors: Four New Nearby High Proper Motion Systems

    Science.gov (United States)

    Bartlett, Jennifer L.; Lurie, John C.; Ianna, Philip A.; Riedel, Adric R.; Finch, Charlie T.; Winters, Jennifer G.; Jao, Wei-Chun; Subasavage, John P.; Henry, Todd J.

    2017-01-01

    Obtaining a well-understood, volume-limited (and ultimately volume-complete) sample of stellar systems within 25 pc is essential for determining the stellar luminosity function, the mass-luminosity relationship, the stellar velocity distribution, and the stellar multiplicity fraction. Such a sample also provides insight into the local star formation history. Towards that end, the Research Consortium On Nearby Stars (RECONS) team measures trigonometric parallaxes to establish which systems truly lie within the 25-pc radius of the Solar Neighborhood. Recent astrometric measurements with the CTIO/SMARTS 0.9-m telescope establish three high proper motion systems as members (2MASS J02511490-0352459, 2MASS J15345704-1418486, and 2MASS J09211410-2104446) and confirm a fourth (2MASS J23062928-0502285). All four proper motions exceed 0.9”/yr. 2MA0251 travels 2.1497±0.0009”/yr in 149.20±0.05° at a distance of 11.0±0.4 pc. 2M2306 moves 1.0344±0.0007”/yr in 118.50±0.08° at a distance of 12.7±0.2 pc. 2MA1534 goes 0.9726±0.0004”/yr in 251.50 ±0.05° at a distance of 10.93±0.10 pc. 2MA0921 shifts 0.9489±0.0003”/yr in 164.70±0.04° at a distance of 12.3±0.2 pc. The corresponding tangential velocities are 112.4, 62.4, 50.4, and 55.5 km/s whereas the median for parallaxes previously published by RECONS is 53 km/s. With radial velocities in the literature of -75.5 to 80.53 km/s, none of these is a candidate member of any young moving groups.To characterize these late M-early L systems more fully, RECONS obtained VRI photometry; their I -band magnitudes range from 14.10 to 16.55. Over their astrometric baselines of 7.75 to 8.99 years, these demonstrated long-term I-band variability of 0.0135 mag. or less, indicating they may be older systems.With each new confirmation, we come closer to completing the census of the Solar Neighborhood.NSF grants AST 05-07711 and AST 09-08402, NASA-SIM, Georgia State University, the University of Virginia, Hampden-Sydney College

  15. HIGH-PRECISION RADIO AND INFRARED ASTROMETRY OF LSPM J1314+1320AB. I. PARALLAX, PROPER MOTIONS, AND LIMITS ON PLANETS

    Energy Technology Data Exchange (ETDEWEB)

    Forbrich, Jan [University of Vienna, Department of Astrophysics, Türkenschanzstr. 17, A-1180 Vienna (Austria); Dupuy, Trent J.; Rizzuto, Aaron; Mann, Andrew W.; Kraus, Adam L. [The University of Texas at Austin, Department of Astronomy, 2515 Speedway C1400, Austin, TX 78712 (United States); Reid, Mark J.; Berger, Edo [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Liu, Michael C.; Aller, Kimberly [Institute for Astronomy, University of Hawai’i, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

    2016-08-10

    We present multi-epoch astrometric radio observations with the Very Long Baseline Array (VLBA) of the young ultracool-dwarf binary LSPM J1314+1320AB. The radio emission comes from the secondary star. Combining the VLBA data with Keck near-infrared adaptive-optics observations of both components, a full astrometric fit of parallax (π {sub abs} = 57.975 ± 0.045 mas, corresponding to a distance of d = 17.249 ± 0.013 pc), proper motion (μ {sub α} {sub cos} {sub δ} = −247.99 ± 0.10 mas yr{sup −1}, μ {sub δ} = −183.58 ± 0.22 mas yr{sup −1}), and orbital motion is obtained. Despite the fact that the two components have nearly identical masses to within ±2%, the secondary’s radio emission exceeds that of the primary by a factor of ≳30, suggesting a difference in stellar rotation history, which could result in different magnetic field configurations. Alternatively, the emission could be anisotropic and beamed toward us for the secondary but not for the primary. Using only reflex motion, we exclude planets of mass 0.7–10 M {sub jup} with orbital periods of 600–10 days, respectively. Additionally, we use the full orbital solution of the binary to derive an upper limit for the semimajor axis of 0.23 au for stable planetary orbits within this system. These limits cover a parameter space that is inaccessible with, and complementary to, near-infrared radial velocity surveys of ultracool dwarfs. Our absolute astrometry will constitute an important test for the astrometric calibration of Gaia .

  16. The imprint of proper motion of nonlinear structures on the cosmic microwave background

    Science.gov (United States)

    Tuluie, Robin; Laguna, Pablo

    1995-01-01

    We investigate the imprint of nonlinear matter condensations on the cosmic microwave background (CMB) in an Omega = 1, cold dark matter (CDM) model universe. Temperature anisotropies are obtained by numerically evolving matter inhomogeneities and CMB photons from the beginning of decoupling until the present epoch. The underlying density field produced by the inhomogeneities is followed from the linear, through the weakly clustered, into the fully nonlinear regime. We concentrate on CMB temperature distortions arising from variations in the gravitational potentials of nonlinear structures. We find two sources of temperature fluctuations produced by time-varying potentials: (1) anisotropies due to intrinsic changes in the gravitational potentials of the inhomogeneities and (2) anisotropies generated by the peculiar, bulk motion of the structures across the microwave sky. Both effects generate CMB anisotropies in the range of 10(exp -7) approximately less than or equal to (Delta T/T) approximately less than or equal to 10(exp -6) on scales of approximately 1 deg. For isolated structures, anisotropies due to proper motion exhibit a dipole-like signature in the CMB sky that in principle could yield information on the transverse velocity of the structures.

  17. Domain wall motion in ferromagnetic systems with perpendicular magnetization

    International Nuclear Information System (INIS)

    Szambolics, H.; Toussaint, J.-Ch.; Marty, A.; Miron, I.M.; Buda-Prejbeanu, L.D.

    2009-01-01

    Although we lack clear experimental evidence, apparently out-of-plane magnetized systems are better suited for spintronic applications than the in-plane magnetized ones, mainly due to the smaller current densities required for achieving domain wall motion. [Co/Pt] multilayers belong to the first category of materials, the out-of-plane magnetization orientation arising from the strong perpendicular magnetocrystalline anisotropy. If the magnetization arranges itself out-of-plane narrow Bloch walls occur. In the present paper, both field and current-driven domain wall motion have been investigated for this system, using micromagnetic simulations. Three types of geometries have been taken into account: bulk, thin film and wire, and for all of them a full comparison is done between the effect of the applied field and injected current. The reduction of the system's dimension induces the decrease of the critical field and the critical current, but it does not influence the domain wall displacement mechanism.

  18. Towards Motion-Insensitive Magnetic Resonance Imaging Using Dynamic Field Measurements

    DEFF Research Database (Denmark)

    Andersen, Mads

    motion during scanning and update the MRI scanner in real-time such that the imaging volume follows the head motion (prospective motion correction). In this thesis, prospective motion correction is presented where head motion is determined from signals measured with an electroencephalography (EEG) cap......Magnetic resonance imaging (MRI) of the brain is frequently used for both clinical diagnosis and brain research. This is due to the great versatility of the technique and the excellent ability to distinguish different types of soft tissue. The image quality is, however, heavily degraded when...

  19. Motion estimation of tagged cardiac magnetic resonance images using variational techniques

    Czech Academy of Sciences Publication Activity Database

    Carranza-Herrezuelo, N.; Bajo, A.; Šroubek, Filip; Santamarta, C.; Cristóbal, G.; Santos, A.; Ledesma-Carbayo, M.J.

    2010-01-01

    Roč. 34, č. 6 (2010), s. 514-522 ISSN 0895-6111 Institutional research plan: CEZ:AV0Z10750506 Keywords : medical imaging processing * motion estimation * variational techniques * tagged cardiac magnetic resonance images * optical flow Subject RIV: JD - Computer Applications, Robotics Impact factor: 1.110, year: 2010 http://library.utia.cas.cz/separaty/2010/ZOI/sroubek- motion estimation of tagged cardiac magnetic resonance images using variational techniques.pdf

  20. Geometric Control Over the Motion of Magnetic Domain Walls

    International Nuclear Information System (INIS)

    N.A. Sinitsyn; V.V. Dobrovitski; S. urazhdin; Avadh Saxena

    2008-01-01

    We propose a method that enables a precise control of magnetic patterns and relies only on the fundamental properties of the wire as well as on the choice of the path in the controlled parameter space but not on the rate of motion along this path. Possible experimental realizations of this mechanism are discussed. In particular, we show that the domain walls in magnetic nanowires can be translated by rotation of the magnetic easy axis or by applying pulses of magnetic field directed transverse to the magnetic easy axis

  1. Solar Magnetized Tornadoes: Rotational Motion in a Tornado-like Prominence

    Science.gov (United States)

    Su, Yang; Gömöry, Peter; Veronig, Astrid; Temmer, Manuela; Wang, Tongjiang; Vanninathan, Kamalam; Gan, Weiqun; Li, YouPing

    2014-04-01

    Su et al. proposed a new explanation for filament formation and eruption, where filament barbs are rotating magnetic structures driven by underlying vortices on the surface. Such structures have been noticed as tornado-like prominences when they appear above the limb. They may play a key role as the source of plasma and twist in filaments. However, no observations have successfully distinguished rotational motion of the magnetic structures in tornado-like prominences from other motions such as oscillation and counter-streaming plasma flows. Here we report evidence of rotational motions in a tornado-like prominence. The spectroscopic observations in two coronal lines were obtained from a specifically designed Hinode/EIS observing program. The data revealed the existence of both cold and million-degree-hot plasma in the prominence leg, supporting the so-called prominence-corona transition region. The opposite velocities at the two sides of the prominence and their persistent time evolution, together with the periodic motions evident in SDO/AIA dark structures, indicate a rotational motion of both cold and hot plasma with a speed of ~5 km s-1.

  2. The Solar Neighborhood. XXV. Discovery of New Proper Motion Stars with 0.40 sec/yr > mu > or = 0.18 sec/yr Between Declinations -47 deg and 00 deg

    Science.gov (United States)

    Boyd, Mark R.; Winters, Jennifer G.; Henry, Todd J.; Jao, Wei-Chun; Finch, Charlie T.; Subasavage, John P.; Hambly, Nigel C.

    2011-01-01

    We present 2817 new southern proper motion systems with 0.40 sec/yr > mu > or = 0.18 sec/yr and declination between 47 deg and 00 deg. This is a continuation of the SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky. We use the same photometric relations as previous searches to provide distance estimates based on the assumption that the objects are single main-sequence stars. We find 79 new red dwarf systems predicted to be within 25 pc, including a few new components of previously known systems. Two systems--SCR 1731-2452 at 9.5 pc and SCR 1746-3214 at 9.9 pc--are anticipated to be within 10 pc. We also find 23 new white dwarf (WD) candidates with distance estimates of 15-66 pc, as well as 360 new red subdwarf candidates. With this search, we complete the SCR sweep of the southern sky for stars with mu > or = 0.18 sec/yr and R(sub 59F) < or = 16.5, resulting in a total of 5042 objects in 4724 previously unreported proper motion systems. Here we provide selected comprehensive lists from our SCR proper motion search to date, including 152 red dwarf systems estimated to be within 25 pc (9 within 10 pc), 46 WDs (10 within 25 pc), and 598 subdwarf candidates. The results of this search suggest that there are more nearby systems to be found at fainter magnitudes and lower proper motion limits than those probed so far.

  3. Self-consistent solution for a collisionless plasma slab in motion across a magnetic field

    International Nuclear Information System (INIS)

    Echim, Marius M.; Lemaire, Joseph F.; Roth, Michel

    2005-01-01

    The problem of the dynamics of a plasma slab moving across a magnetic field is treated in the framework of the kinetic theory. A velocity distribution function (VDF) is found for each plasma species, electrons and protons, in terms of the constants of motion defined by the geometry of the problem. The zero- and first-order moments of the VDF are introduced into the right-hand side term of Maxwell's equations to compute the electric and magnetic vector potentials and corresponding fields. The solutions are found numerically. We obtain a region of plasma convection--the slab proper--where the plasma moves with a uniform velocity, V x =V 0 =(ExB/B 2 ) x . At the core margins two plasma 'wings' are formed, each being the result of a pair of interpenetrated boundary layers with different transition lengths. Inside these wings, the plasma velocity is not uniform, V x ≠(ExB/B 2 ) x . It decreases from the maximum value obtained in the core to a minimum value in the central region of the wings where a flow reversal is found with the plasma convecting in the opposite direction to the core motion. There is also an asymmetry of the velocity gradient at the borders of the core, which results in a corresponding asymmetry in the thickness of the wings. Furthermore, it is found that the reversed plasma flow in the thinner wing is larger than that in the broader wing. For a fixed direction of the magnetic field the two plasma wings interchange position with respect to the center of the slab when the plasma bulk velocity reverses sign

  4. Measurements of ground motion and magnet vibrations at the APS

    International Nuclear Information System (INIS)

    Shiltsev, V.

    1996-01-01

    This article presents results of ground motion and magnet vibrations measurements at the Advanced Photon Source. The experiments were done over a wide, frequency range (0-05-100 Hz) with the use of SM-3KV-type seismic probes from the Budker Institute of Nuclear Physics (Russia). Spectral power densities of vertical and horizontal motions of the APS hall floor and quadrupoles on regular supports were obtained. Also investigated were magnet vibrations induced by designed cooling water flow and spectral characteristics of spatial correlation of the quadrupole vibrations at different sectors of the ring. The influence of personnel activity in the hall and traffic under the ring on the slow motion of storage ring elements were observed. Amplitudes of vibrations at the APS are compared with results of seismic measurements at some other accelerators

  5. Magnetization reversal in ferromagnetic spirals via domain wall motion

    Science.gov (United States)

    Schumm, Ryan D.; Kunz, Andrew

    2016-11-01

    Domain wall dynamics have been investigated in a variety of ferromagnetic nanostructures for potential applications in logic, sensing, and recording. We present a combination of analytic and simulated results describing the reliable field driven motion of a domain wall through the arms of a ferromagnetic spiral nanowire. The spiral geometry is capable of taking advantage of the benefits of both straight and circular wires. Measurements of the in-plane components of the spirals' magnetization can be used to determine the angular location of the domain wall, impacting the magnetoresistive applications dependent on the domain wall location. The spirals' magnetization components are found to depend on the spiral parameters: the initial radius and spacing between spiral arms, along with the domain wall location. The magnetization is independent of the parameters of the rotating field used to move the domain wall, and therefore the model is valid for current induced domain wall motion as well. The speed of the domain wall is found to depend on the frequency of the rotating driving field, and the domain wall speeds can be reliably varied over several orders of magnitude. We further demonstrate a technique capable of injecting multiple domain walls and show the reliable and unidirectional motion of domain walls through the arms of the spiral.

  6. SOLAR MAGNETIZED TORNADOES: ROTATIONAL MOTION IN A TORNADO-LIKE PROMINENCE

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yang; Veronig, Astrid; Temmer, Manuela; Vanninathan, Kamalam [IGAM-Kanzelhöhe Observatory, Institute of Physics, University of Graz, Universitätsplatz 5, A-8010 Graz (Austria); Gömöry, Peter [Astronomical Institute of the Slovak Academy of Sciences, SK-05960 Tatranská Lomnica (Slovakia); Wang, Tongjiang [Department of Physics, the Catholic University of America, Washington, DC 20064 (United States); Gan, Weiqun; Li, YouPing, E-mail: yang.su@uni-graz.at [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2014-04-10

    Su et al. proposed a new explanation for filament formation and eruption, where filament barbs are rotating magnetic structures driven by underlying vortices on the surface. Such structures have been noticed as tornado-like prominences when they appear above the limb. They may play a key role as the source of plasma and twist in filaments. However, no observations have successfully distinguished rotational motion of the magnetic structures in tornado-like prominences from other motions such as oscillation and counter-streaming plasma flows. Here we report evidence of rotational motions in a tornado-like prominence. The spectroscopic observations in two coronal lines were obtained from a specifically designed Hinode/EIS observing program. The data revealed the existence of both cold and million-degree-hot plasma in the prominence leg, supporting the so-called prominence-corona transition region. The opposite velocities at the two sides of the prominence and their persistent time evolution, together with the periodic motions evident in SDO/AIA dark structures, indicate a rotational motion of both cold and hot plasma with a speed of ∼5 km s{sup –1}.

  7. SOLAR MAGNETIZED TORNADOES: ROTATIONAL MOTION IN A TORNADO-LIKE PROMINENCE

    International Nuclear Information System (INIS)

    Su, Yang; Veronig, Astrid; Temmer, Manuela; Vanninathan, Kamalam; Gömöry, Peter; Wang, Tongjiang; Gan, Weiqun; Li, YouPing

    2014-01-01

    Su et al. proposed a new explanation for filament formation and eruption, where filament barbs are rotating magnetic structures driven by underlying vortices on the surface. Such structures have been noticed as tornado-like prominences when they appear above the limb. They may play a key role as the source of plasma and twist in filaments. However, no observations have successfully distinguished rotational motion of the magnetic structures in tornado-like prominences from other motions such as oscillation and counter-streaming plasma flows. Here we report evidence of rotational motions in a tornado-like prominence. The spectroscopic observations in two coronal lines were obtained from a specifically designed Hinode/EIS observing program. The data revealed the existence of both cold and million-degree-hot plasma in the prominence leg, supporting the so-called prominence-corona transition region. The opposite velocities at the two sides of the prominence and their persistent time evolution, together with the periodic motions evident in SDO/AIA dark structures, indicate a rotational motion of both cold and hot plasma with a speed of ∼5 km s –1

  8. Magnetic motion capture system using LC resonant magnetic marker composed of Ni-Zn ferrite core

    International Nuclear Information System (INIS)

    Hashi, S.; Toyoda, M.; Ohya, M.; Okazaki, Y.; Yabukami, S.; Ishiyama, K.; Arai, K. I.

    2006-01-01

    We have proposed a magnetic motion capture system using an LC resonant magnetic marker. The proposed system is composed of an exciting coil, an LC marker, and a 5x5-matrix search coil array (25 search coils). The LC marker is small and has a minimal circuit with no battery and can be driven wirelessly by the action of electromagnetic induction. It consists of a Ni-Zn ferrite core (3 mmφx10 mm) with a wound coil and a chip capacitor, forming an LC series circuit with a resonant frequency of 186 kHz. The relative position accuracy of the system is less than 1 mm within the area of 100 mm 3 up to 150 mm from the search coil array. Compared with dc magnetic systems, the proposed system is applicable for precision motion capture in optically isolated spaces without magnetic shielding because the system is not greatly influenced by earth field noise

  9. Measurements of ground motion and magnets vibrations at the APS

    International Nuclear Information System (INIS)

    Shil'tsev, V.D.

    1994-01-01

    This article presents results of ground motion and magnets vibrations measurements at the Advanced Photon Source. The experiments were done over wide frequency range 0.05-100 Hz with use of SM-3KV type seismic probes from Budker Institute of Nuclear Physics (Russia). Spectral power densities of vertical and horizontal motions of the APS hall floor and quadrupoles on regular supports were obtained. There were also investigated magnets vibrations induced by designed cooling water flow and spectral characteristics of spatial correlation of the quads vibration at different sectors of the ring. Influence of personnel activity in the hall and traffic under the ring on slow motion of storage ring elements were observed. Amplitudes of vibrations at the APS are compared with results of seismic measurements at some other accelerators. 9 refs.; 10 figs.; 1 tab

  10. Brownian motion of massive skyrmions in magnetic thin films

    International Nuclear Information System (INIS)

    Troncoso, Roberto E.; Núñez, Álvaro S.

    2014-01-01

    We report on the thermal effects on the motion of current-driven massive magnetic skyrmions. The reduced equation for the motion of skyrmion has the form of a stochastic generalized Thiele’s equation. We propose an ansatz for the magnetization texture of a non-rigid single skyrmion that depends linearly with the velocity. By using this ansatz it is found that the skyrmion mass tensor is closely related to intrinsic skyrmion parameters, such as Gilbert damping, skyrmion-charge and dissipative force. We have found an exact expression for the average drift velocity as well as the mean-square velocity of the skyrmion. The longitudinal and transverse mobility of skyrmions for small spin-velocity of electrons is also determined and found to be independent of the skyrmion mass

  11. Brownian motion of massive skyrmions in magnetic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Troncoso, Roberto E., E-mail: r.troncoso.c@gmail.com [Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Avda. Ecuador 3493, Santiago 9170124 (Chile); Núñez, Álvaro S., E-mail: alnunez@dfi.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago (Chile)

    2014-12-15

    We report on the thermal effects on the motion of current-driven massive magnetic skyrmions. The reduced equation for the motion of skyrmion has the form of a stochastic generalized Thiele’s equation. We propose an ansatz for the magnetization texture of a non-rigid single skyrmion that depends linearly with the velocity. By using this ansatz it is found that the skyrmion mass tensor is closely related to intrinsic skyrmion parameters, such as Gilbert damping, skyrmion-charge and dissipative force. We have found an exact expression for the average drift velocity as well as the mean-square velocity of the skyrmion. The longitudinal and transverse mobility of skyrmions for small spin-velocity of electrons is also determined and found to be independent of the skyrmion mass.

  12. Dynamics of solar magnetic fields. VI. Force-free magnetic fields and motions of magnetic foot-points

    International Nuclear Information System (INIS)

    Low, B.C.; Nakagawa, Y.

    1975-01-01

    A mathematical model is developed to consider the evolution of force-free magnetic fields in relation to the displacements of their foot-points. For a magnetic field depending on only two Cartesian coordinates and time, the problem reduces to solving a nonlinear elliptic partial differential equation. As illustration of the physical process, two specific examples of evolving force-free magnetic fields are examined in detail, one evolving with rising and the other with descending field lines. It is shown that these two contrasting behaviors of the field lines correspond to sheared motions of their foot-points of quite different characters. The physical implications of these two examples of evolving force-free magnetic fields are discussed. (auth)

  13. Photometry and Proper Motions of M, L, and T Dwarfs from the Pan-STARRS1 3π Survey

    Science.gov (United States)

    Best, William M. J.; Magnier, Eugene A.; Liu, Michael C.; Aller, Kimberly M.; Zhang, Zhoujian; Burgett, W. S.; Chambers, K. C.; Draper, P.; Flewelling, H.; Kaiser, N.; Kudritzki, R.-P.; Metcalfe, N.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

    2018-01-01

    We present a catalog of 9888 M, L and T dwarfs detected in the Pan-STARRS1 3π Survey (PS1), covering three-quarters of the sky. Our catalog contains nearly all known objects of spectral types L0–T2 in the PS1 field, with objects as early as M0 and as late as T9, and includes PS1, 2MASS, AllWISE, and Gaia DR1 photometry. We analyze the different types of photometry reported by PS1 and use two types in our catalog in order to maximize both depth and accuracy. Using parallaxes from the literature, we construct empirical SEDs for field ultracool dwarfs spanning 0.5–12 μm. We determine typical colors of M0–T9 dwarfs and highlight the distinctive colors of subdwarfs and young objects. We combine astrometry from PS1, 2MASS, and Gaia DR1 to calculate new proper motions for our catalog. We achieve a median precision of 2.9 mas yr‑1, a factor of ≈3‑10 improvement over previous large catalogs. Our catalog contains proper motions for 2405 M6–T9 dwarfs and includes the largest set of homogeneous proper motions for L and T dwarfs published to date, 406 objects for which there were no previous measurements, and 1176 objects for which we improve upon previous literature values. We analyze the kinematics of ultracool dwarfs in our catalog and find evidence that bluer but otherwise generic late-M and L field dwarfs (i.e., not subdwarfs) tend to have tangential velocities higher than those of typical field objects. With the public release of the PS1 data, this survey will continue to be an essential tool for characterizing the ultracool dwarf population.

  14. Constants of motion for the planar orbit of a charged particle in a static and uniform magnetic field: the magnetic Laplace–Runge–Lenz vector

    International Nuclear Information System (INIS)

    Velasco-Martínez, D; Kunold, A; Cardoso, J L; Ibarra-Sierra, V G; Sandoval-Santana, J C

    2014-01-01

    In this paper we introduce an alternative approach to studying the motion of a planar charged particle subject to a static uniform magnetic field. It is well known that an electric charge under a uniform magnetic field has a planar motion if its initial velocity is perpendicular to the magnetic field. Although some constants of motion (CsM), as the energy and the angular momentum, have been widely discussed for this system, others have been neglected. We find that the angular momentum, the generator of the magnetic translations and the magnetic Laplace–Runge–Lenz vector are CsM for this particular system. We show also that these three quantities form an orthogonal basis of vectors. The present work addresses many aspects of the motion of a charged particle in a magnetic field that should be useful for students and tutors of the classical mechanics courses at the senior undergraduate level. (paper)

  15. A canonical perturbation method for computing the guiding-center motion in magnetized axisymmetric plasma columns

    International Nuclear Information System (INIS)

    Gratreau, P.

    1987-01-01

    The motion of charged particles in a magnetized plasma column, such as that of a magnetic mirror trap or a tokamak, is determined in the framework of the canonical perturbation theory through a method of variation of constants which preserves the energy conservation and the symmetry invariance. The choice of a frame of coordinates close to that of the magnetic coordinates allows a relatively precise determination of the guiding-center motion with a low-ordered approximation in the adiabatic parameter. A Hamiltonian formulation of the motion equations is obtained

  16. Magnetic fish-robot based on multi-motion control of a flexible magnetic actuator.

    Science.gov (United States)

    Kim, Sung Hoon; Shin, Kyoosik; Hashi, Shuichiro; Ishiyama, Kazushi

    2012-09-01

    This paper presents a biologically inspired fish-robot driven by a single flexible magnetic actuator with a rotating magnetic field in a three-axis Helmholtz coil. Generally, magnetic fish-robots are powered by alternating and gradient magnetic fields, which provide a single motion such as bending the fish-robot's fins. On the other hand, a flexible magnetic actuator driven by an external rotating magnetic field can create several gaits such as the bending vibration, the twisting vibration, and their combination. Most magnetic fish-like micro-robots do not have pectoral fins on the side and are simply propelled by the tail fin. The proposed robot can swim and perform a variety of maneuvers with the addition of pectoral fins and control of the magnetic torque direction. In this paper, we find that the robot's dynamic actuation correlates with the magnetic actuator and the rotating magnetic field. The proposed robot is also equipped with new features, such as a total of six degrees of freedom, a new control method that stabilizes posture, three-dimensional swimming, a new velocity control, and new turning abilities.

  17. Magnetic fish-robot based on multi-motion control of a flexible magnetic actuator

    International Nuclear Information System (INIS)

    Kim, Sung Hoon; Hashi, Shuichiro; Ishiyama, Kazushi; Shin, Kyoosik

    2012-01-01

    This paper presents a biologically inspired fish-robot driven by a single flexible magnetic actuator with a rotating magnetic field in a three-axis Helmholtz coil. Generally, magnetic fish-robots are powered by alternating and gradient magnetic fields, which provide a single motion such as bending the fish-robot's fins. On the other hand, a flexible magnetic actuator driven by an external rotating magnetic field can create several gaits such as the bending vibration, the twisting vibration, and their combination. Most magnetic fish-like micro-robots do not have pectoral fins on the side and are simply propelled by the tail fin. The proposed robot can swim and perform a variety of maneuvers with the addition of pectoral fins and control of the magnetic torque direction. In this paper, we find that the robot's dynamic actuation correlates with the magnetic actuator and the rotating magnetic field. The proposed robot is also equipped with new features, such as a total of six degrees of freedom, a new control method that stabilizes posture, three-dimensional swimming, a new velocity control, and new turning abilities. (paper)

  18. Large-scale fluid motion in the earth's outer core estimated from non-dipole magnetic field data

    International Nuclear Information System (INIS)

    Matsushima, Masaki; Honkura, Yoshimori

    1989-01-01

    Fluid motions in the Earth's outer core can be estimated from magnetic field data at the Earth's surface based on some assumptions. The basic standpoint here is that the non-dipole magnetic field is generated by the interaction between a strong toroidal magnetic field, created by differential rotation, and the convective motion in the outer core. Large-scale convective motions are studied to express them in terms of the poloidal velocity field expanded into a series of spherical harmonics. The radial distribution of differential rotation is estimated from the balance between the effective couple due to angular momentum transfer and the electromagnetic couple. Then the radial dependence of the toroidal magnetic field is derived from the interaction between the differential rotation thus estimated and the dipole magnetic field within the outer core. Magnetic field data are applied to a secular variation model which takes into account the fluctuations of the standing and drifting parts of the non-zonal magnetic field. The velocity field in the outer core is estimated for two cases. It is revealed that the pattern of convective motions is generally characterized by large-scale motions in the quasi-steady case. In the non-steady case, the magnitude of the velocity field is much larger, indicating a more dynamic feature. (N.K.)

  19. A PROPER MOTION STUDY OF THE HARO 6-10 OUTFLOW: EVIDENCE FOR A SUBARCSECOND BINARY

    International Nuclear Information System (INIS)

    Wilking, Bruce A.; Gerling, Bradley M.; Gibb, Erika; Marvel, Kevin B.; Claussen, Mark J.; Wootten, Alwyn

    2012-01-01

    We present single-dish and very long baseline interferometry observations of an outburst of water maser emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus molecular cloud and contains a visible T Tauri star with an infrared companion 1.''3 north. Using the Very Long Baseline Array, we obtained five observations spanning three months and derived absolute positions for 20 distinct maser spots. Three of the masers can be traced over three or more epochs, enabling us to extract absolute proper motions and tangential velocities. We deduce that the masers represent one side of a bipolar outflow that lies nearly in the plane of the sky with an opening angle of ∼45°. They are located within 50 mas of the southern component of the binary, the visible T Tauri star Haro 6-10S. The mean position angle on the sky of the maser proper motions (∼220°) suggests they are related to the previously observed giant Herbig-Haro (HH) flow which includes HH 410, HH 411, HH 412, and HH 184A-E. A previously observed HH jet and extended radio continuum emission (mean position angle of ∼190°) must also originate in the vicinity of Haro 6-10S and represent a second, distinct outflow in this region. We propose that a yet unobserved companion within 150 mas of Haro 6-10S is responsible for the giant HH/maser outflow while the visible star is associated with the HH jet. Despite the presence of H 2 emission in the spectrum of the northern component of the binary, Haro 6-10N, none of outflows/jets can be tied directly to this young stellar object.

  20. A PROPER MOTION STUDY OF THE HARO 6-10 OUTFLOW: EVIDENCE FOR A SUBARCSECOND BINARY

    Energy Technology Data Exchange (ETDEWEB)

    Wilking, Bruce A.; Gerling, Bradley M.; Gibb, Erika [Department of Physics and Astronomy, University of Missouri-St. Louis, 1 University Boulevard, St. Louis, MO 63121 (United States); Marvel, Kevin B. [American Astronomical Society, 2000 Florida Avenue, NW, Suite 400, Washington, DC 20009 (United States); Claussen, Mark J. [National Radio Astronomy Observatory (NRAO), Array Operations Center, P.O. Box 0, 1003 Lopezville Road, Socorro, NM 87801 (United States); Wootten, Alwyn, E-mail: bwilking@umsl.edu, E-mail: bmg5333@truman.edu, E-mail: gibbe@umsl.edu, E-mail: marvel@aas.org, E-mail: mclausse@nrao.edu, E-mail: awootten@nrao.edu [NRAO, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States)

    2012-07-10

    We present single-dish and very long baseline interferometry observations of an outburst of water maser emission from the young binary system Haro 6-10. Haro 6-10 lies in the Taurus molecular cloud and contains a visible T Tauri star with an infrared companion 1.''3 north. Using the Very Long Baseline Array, we obtained five observations spanning three months and derived absolute positions for 20 distinct maser spots. Three of the masers can be traced over three or more epochs, enabling us to extract absolute proper motions and tangential velocities. We deduce that the masers represent one side of a bipolar outflow that lies nearly in the plane of the sky with an opening angle of {approx}45 Degree-Sign . They are located within 50 mas of the southern component of the binary, the visible T Tauri star Haro 6-10S. The mean position angle on the sky of the maser proper motions ({approx}220 Degree-Sign ) suggests they are related to the previously observed giant Herbig-Haro (HH) flow which includes HH 410, HH 411, HH 412, and HH 184A-E. A previously observed HH jet and extended radio continuum emission (mean position angle of {approx}190 Degree-Sign ) must also originate in the vicinity of Haro 6-10S and represent a second, distinct outflow in this region. We propose that a yet unobserved companion within 150 mas of Haro 6-10S is responsible for the giant HH/maser outflow while the visible star is associated with the HH jet. Despite the presence of H{sub 2} emission in the spectrum of the northern component of the binary, Haro 6-10N, none of outflows/jets can be tied directly to this young stellar object.

  1. Quantum revivals in the motion of electron in magnetic field

    International Nuclear Information System (INIS)

    Filipowicz, P.; Mostowski, J.

    1981-01-01

    We show that the motion of a relativistic electron in constant homogeneous magnetic field exhibits quasiperiodic behaviour (quantum revivals) and discuss the possibility of their observation. (author)

  2. Test-particle motion in Einstein's unified field theory. III. Magnetic monopoles and charged particles

    International Nuclear Information System (INIS)

    Johnson, C.R.

    1986-01-01

    In a previous paper (paper I), we developed a method for finding the exact equations of structure and motion of multipole test particles in Einstein's unified field theory: the theory of the nonsymmetric field. In that paper we also applied the method and found in Einstein's unified field theory the equations of structure and motion of neutral pole-dipole test particles possessing no electromagnetic multipole moments. In a second paper (paper II), we applied the method and found in Einstein's unified field theory the exact equations of structure and motion of charged test particles possessing no magnetic monopole moments. In the present paper (paper III), we apply the method and find in Einstein's unified field theory the exact equations of structure and motion of charged test particles possessing magnetic monopole moments. It follows from the form of these equations of structure and motion that in general in Einstein's unified field theory a test particle possessing a magnetic monopole moment in a background electromagnetic field must also possess spin

  3. Quasi-adiabatic motion of energetic particles in a dipole magnetic field

    International Nuclear Information System (INIS)

    Il'in, V.D.; Kuznetsov, S.N.; Yushkov, B.Yu.

    1992-01-01

    A moving coordinate system for a dipole magnetic field, in which reversible variations of magnetic moment for the range of obvious violations of adiabatic conditions are absent, and the description of magnetic moment violations is relatively simple, is considered. Constructing of a coordinate system, features of the central trajectory, determining its motion, the application range, the main application field and consequences are discussed. 11 refs.; 3 figs

  4. Magnetowetting and sliding motion of a sessile ferrofluid droplet in the presence of a permanent magnet.

    Science.gov (United States)

    Nguyen, Nam-Trung; Zhu, Guiping; Chua, Yong-Chin; Phan, Vinh-Nguyen; Tan, Say-Hwa

    2010-08-03

    Motion of a droplet on a planar surface has applications in droplet-based lab on a chip technology. This paper reports the experimental results of the shape, contact angles, and motion of ferrofluid droplets driven by a permanent magnet on a planar homogeneous surface. The water-based ferrofluid in use is a colloidal suspension of single-domain magnetic nanoparticles. The effect of the magnetic field on the apparent contact angle of the ferrofluid droplet was first investigated. The results show that an increasing magnetic flux decreases the apparent contact angle of a sessile ferrofluid droplet. Next, the dynamic contact angle was investigated by observing the shape and the motion of a sessile ferrofluid droplet. The advancing and receding contact angles of the moving ferrofluid were measured at different moving speeds and magnetic field strengths. The measured contact angles were used to estimate the magnitude of the forces involved in the sliding motion. Scaling analysis was carried out to derive the critical velocity, beyond which the droplet is not able to catch up with the moving magnet.

  5. Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue

    2012-01-01

    In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...... current analysis. The model takes the eddy current effect of PMs into account in determination of the magnetic field in the air-gap and in the magnet regions. The eddy current losses generated in the magnets are properly interpreted. Design improvements for reducing the eddy current losses are suggested...

  6. Understanding motion of twin boundary - a key to magnetic shape memory effect

    Czech Academy of Sciences Publication Activity Database

    Heczko, Oleg

    2014-01-01

    Roč. 50, č. 11 (2014), s. 2505807 ISSN 0018-9464 R&D Projects: GA ČR(CZ) GAP107/11/0391 Institutional support: RVO:68378271 Keywords : magnetic field-induced strain * magnetic field-induced twin boundary motion * magnetoelasticity * magnetomechanical effects * martensitic transformation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.386, year: 2014

  7. Vacuum arc cathode spot motion in oblique magnetic fields: An interpretation of the Robson experiment

    Energy Technology Data Exchange (ETDEWEB)

    Beilis, I. I. [Electrical Discharge and Plasma Laboratory, School of Electrical Engineering, Fleischman Faculty of Engineering, Tel Aviv University, P.O.B. 39040, Tel Aviv 69978 (Israel)

    2016-09-15

    A model was developed of vacuum arc cathode spot motion in a magnetic field that obliquely intercepts the cathode surface. The model takes into account a force under an electric field caused by retrograde spot motion across the normal component of the magnetic field, producing a drift velocity component in the direction of the acute angle between the magnetic field and the cathode surface. The relationship between velocity of the retrograde direction and drift velocity of the cathode spot motion to the acute angle was developed. The dependencies of the drift angle θ on the acute angle φ, magnetic field strength B, and arc current I were calculated. It was found that the calculated θ increased with φ, B, and I in accordance with Robson's measurements.

  8. Measurement of the X-Ray Proper Motion in the South-East Rim of RXJ1713.7-3946

    Science.gov (United States)

    Acero, Fabio; Katsuda, Saturo; Ballet, Jean; Petre, Robert

    2017-01-01

    We report on the first proper motion measurement in the supernova remnant RX J1713.73946 using the XMM-Newton X-ray telescope on a 13 yr time interval. This expansion measurement is carried out in the south-east region of the remnant, where two sharp filament structures are observed. For the outermost filament, the proper motion is 0.75(+0.05-0.06) +/- 0.069 syst arcsec/ yr which is equivalent to a shock speed of approx. 3500 km/s at a distance of 1 kpc. In contrast with the bright north-west region, where the shock is interacting with the border of the cavity, the shock in the south-east region is probably expanding in the original ambient medium carved by the progenitor and can be used to derive the current density at the shock and the age of the remnant. In the case where the shock is evolving in a wind profile (p varies as r(sup -s), s = 2) or in a uniform medium (s = 0), we estimate an age of approx. 2300 yr and approx.1800 yr respectively for an ejecta power-law index of n = 9. The specific case of an ejecta power-law index of n = 7, and s = 0, yields an age of approx. 1500 yr, which would reconcile RX J1713.73946 with the historical records of SN 393. In all scenarios, we derive similar upstream densities of the order of 0.01/cu cm, compatible with the lack of thermal X-rays from the shocked ambient medium.

  9. TEACHING AND TRAINING WITH MOTION PICTURES (MAGNETIC SOUND).

    Science.gov (United States)

    Bell and Howell Co., Lincolnwood, IL.

    THE PREPARATION OF A MAGNETIC-SOUND TRACK FOR 16 MM. MOTION PICTURE FILMS IS DESCRIBED. IN SCRIPT PREPARATION, THE SCRIPT SHOULD BE WRITTEN IN NARRATIVE FORM TO INCLUDE ALL SHOTS NEEDED AND TO SUPPLEMENT AND GIVE INFORMATION NOT IN THE FILM. LANGUAGE SHOULD BE KEPT SIMPLE, AND UNAVOIDABLE TECHNICAL TERMS SHOULD BE EXPLAINED. IN REWRITING THE…

  10. Characterization of the Praesepe Star Cluster by Photometry and Proper Motions With 2MASS, PPMXL, and Pan-STARRS

    Science.gov (United States)

    2014-03-20

    reserved. Printed in the U.S.A. CHARACTERIZATION OF THE PRAESEPE STAR CLUSTER BY PHOTOMETRY AND PROPER MOTIONS WITH 2MASS , PPMXL, AND Pan-STARRS P. F. Wang1... 2MASS ) and the Sloan Digital Sky Survey (SDSS) data, covering a sky area of 100 deg2, Adams et al. (2002) extended the lower main sequence to 0.1M, and...incompleteness is caused by the detection limits of USNO-B1 and 2MASS . Recently, Khalaj & Baumgardt (2013) used SDSS and PPMXL data to characterize

  11. Spin Hall driven domain wall motion in magnetic bilayers coupled by a magnetic oxide interlayer

    Science.gov (United States)

    Liu, Yang; Furuta, Masaki; Zhu, Jian-Gang Jimmy

    2018-05-01

    mCell, previously proposed by our group, is a four-terminal magnetoresistive device with isolated write- and read-paths for all-spin logic and memory applications. A mCell requires an electric-insulating magnetic layer to couple the spin Hall driven write-path to the magnetic free layer of the read-path. Both paths are magnetic layers with perpendicular anisotropy and their perpendicularly oriented magnetization needs to be maintained with this insertion layer. We have developed a magnetic oxide (FeOx) insertion layer to serve for these purposes. We show that the FeOx insertion layer provides sufficient magnetic coupling between adjacent perpendicular magnetic layers. Resistance measurement shows that this magnetic oxide layer can act as an electric-insulating layer. In addition, spin Hall driven domain wall motion in magnetic bi-layers coupled by the FeOx insertion layer is significantly enhanced compared to that in magnetic single layer; it also requires low voltage threshold that poses possibility for power-efficient device applications.

  12. Current-induced domain wall motion in magnetic nanowires with spatial variation

    International Nuclear Information System (INIS)

    Ieda, Jun'ichi; Sugishita, Hiroki; Maekawa, Sadamichi

    2010-01-01

    We model current-induced domain wall motion in magnetic nanowires with the variable width. Employing the collective coordinate method we trace the wall dynamics. The effect of the width modulation is implemented by spatial dependence of an effective magnetic field. The wall destination in the potential energy landscape due to the magnetic anisotropy and the spatial nonuniformity is obtained as a function of the current density. For a nanowire of a periodically modulated width, we identify three (pinned, nonlinear, and linear) current density regimes for current-induced wall motion. The threshold current densities depend on the pulse duration as well as the magnitude of wire modulation. In the nonlinear regime, application of ns order current pulses results in wall displacement which opposes or exceeds the prediction of the spin transfer mechanism. The finding explains stochastic nature of the domain wall displacement observed in recent experiments.

  13. Measurement of the X-ray proper motion in the south-east rim of RX J1713.7-3946

    Science.gov (United States)

    Acero, Fabio; Katsuda, Satoru; Ballet, Jean; Petre, Robert

    2017-01-01

    We report on the first proper motion measurement in the supernova remnant RX J1713.7-3946 using the XMM-Newton X-ray telescope on a 13 yr time interval. This expansion measurement is carried out in the south-east region of the remnant, where two sharp filament structures are observed. For the outermost filament, the proper motion is arcsec yr-1 which is equivalent to a shock speed of 3500 km s-1 at a distance of 1 kpc. In contrast with the bright north-west region, where the shock is interacting with the border of the cavity, the shock in the south-east region is probably expanding in the original ambient medium carved by the progenitor and can be used to derive the current density at the shock and the age of the remnant. In the case where the shock is evolving in a wind profile (ρ ∝ r- s, s = 2) or in a uniform medium (s = 0), we estimate an age of 2300 yr and 1800 yr respectively for an ejecta power-law index of n = 9. The specific case of an ejecta power-law index of n = 7, and s = 0, yields an age of 1500 yr, which would reconcile RX J1713.7-3946 with the historical records of SN 393. In all scenarios, we derive similar upstream densities of the order of 0.01 cm-3, compatible with the lack of thermal X-rays from the shocked ambient medium.

  14. Vertical motions in an intense magnetic flux tube

    International Nuclear Information System (INIS)

    Roberts, B.; Webb, A.R.

    1978-01-01

    The recent discovery of localised intense magnetic fields in the solar photosphere is one of the major surprises of the past few years. Here the theoretical nature of small amplitude motions in such an intense magnetic flux tube, within which the field strength may reach 2 kG is considered. A systematic derivation of the governing 'expansion' equations is given for a vertical slender tube, taking into account the dependence upon height of the buoyancy, compressibility and magnetic forces. Several special cases (e.g. the isothermal atmosphere) are considered as well as a more realistic, non-isothermal, solar atmosphere. The expansion procedure is shown to give good results in the special case of a uniform basic-state (in which gravity is negligible) and for which a more exact treatment is possible. (Auth.)

  15. Proper Motions and Structural Parameters of the Galactic Globular Cluster M71

    Energy Technology Data Exchange (ETDEWEB)

    Cadelano, M.; Dalessandro, E.; Ferraro, F. R.; Miocchi, P.; Lanzoni, B.; Pallanca, C. [Dipartimento di Fisica e Astronomia, Università di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy); Massari, D. [INAF—Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy)

    2017-02-20

    By exploiting two ACS/ HST data sets separated by a temporal baseline of ∼7 years, we have determined the relative stellar proper motions (PMs; providing membership) and the absolute PM of the Galactic globular cluster M71. The absolute PM has been used to reconstruct the cluster orbit within a Galactic, three-component, axisymmetric potential. M71 turns out to be in a low-latitude disk-like orbit inside the Galactic disk, further supporting the scenario in which it lost a significant fraction of its initial mass. Since large differential reddening is known to affect this system, we took advantage of near-infrared, ground-based observations to re-determine the cluster center and density profile from direct star counts. The new structural parameters turn out to be significantly different from the ones quoted in the literature. In particular, M71 has a core and a half-mass radii almost 50% larger than previously thought. Finally, we estimate that the initial mass of M71 was likely one order of magnitude larger than its current value, thus helping to solve the discrepancy with the observed number of X-ray sources.

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

    Energy Technology Data Exchange (ETDEWEB)

    Inarrea, Manuel [Universidad de La Rioja, Area de Fisica Aplicada, 26006 Logrono (Spain)], E-mail: manuel.inarrea@unirioja.es

    2009-05-30

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

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

    International Nuclear Information System (INIS)

    Inarrea, Manuel

    2009-01-01

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

  18. Ion motion in the current sheet with sheared magnetic field – Part 2: Non-adiabatic effects

    Directory of Open Access Journals (Sweden)

    A. V. Artemyev

    2013-10-01

    Full Text Available We investigate dynamics of charged particles in current sheets with the sheared magnetic field. In our previouspaper (Artemyev et al., 2013 we studied the particle motion in such magnetic field configurations on the basis of the quasi-adiabatic theory and conservation of the quasi-adiabatic invariant. In this paper we concentrate on violation of the adiabaticity due to jumps of this invariant and the corresponding effects of stochastization of a particle motion. We compare effects of geometrical and dynamical jumps, which occur due to the presence of the separatrix in the phase plane of charged particle motion. We show that due to the presence of the magnetic field shear, the average value of dynamical jumps is not equal to zero. This effect results in the decrease of the time interval necessary for stochastization of trapped particle motion. We investigate also the effect of the magnetic field shear on transient trajectories, which cross the current sheet boundaries. Presence of the magnetic field shear leads to the asymmetry of reflection and transition of particles in the current sheet. We discuss the possible influence of single-particle effects revealed in this paper on the current sheet structure and dynamics.

  19. Reversible rectification of vortex motion in magnetic and non-magnetic asymmetric pinning potentials

    International Nuclear Information System (INIS)

    Gonzalez, E.M.; Gonzalez, M.P.; Nunez, N.O.; Villegas, J.E.; Anguita, J.V.; Jaafa, M.; Asenjo, A.; Vicent, J.L.

    2006-01-01

    Nb films have been grown on arrays of asymmetric pinning centers. The lattice vortex dynamics could be modified, almost at will, by periodic pinning potentials. In the case of asymmetric pinning potentials a vortex ratchet effect occurs: the vortex lattice motion is rectified. That is, an injected ac current yields an output dc voltage, which polarity could be tuned. The output signal polarity could be switched with the applied magnetic field and the ac current strength. Ratchet effect occurs when asymmetric potentials induce outward particles flow under external fluctuations in the lack of driven direct outward forces. The output signal is similar using magnetic or non-magnetic submicrometric array of pinning centers. This device works as an adiabatic rocking ratchet. This superconducting ratchet could be a model to study biological motors

  20. Tycho- Gaia Astrometric Solution Parallaxes and Proper Motions for Five Galactic Globular Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, Laura L.; Van der Marel, Roeland P., E-mail: lwatkins@stsci.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore MD 21218 (United States)

    2017-04-20

    We present a pilot study of Galactic globular cluster (GC) proper motion (PM) determinations using Gaia data. We search for GC stars in the Tycho- Gaia Astrometric Solution (TGAS) catalog from Gaia Data Release 1 (DR1), and identify five members of NGC 104 (47 Tucanae), one member of NGC 5272 (M3), five members of NGC 6121 (M4), seven members of NGC 6397, and two members of NGC 6656 (M22). By taking a weighted average of member stars, fully accounting for the correlations between parameters, we estimate the parallax (and, hence, distance) and PM of the GCs. This provides a homogeneous PM study of multiple GCs based on an astrometric catalog with small and well-controlled systematic errors and yields random PM errors similar to existing measurements. Detailed comparison to the available Hubble Space Telescope ( HST ) measurements generally shows excellent agreement, validating the astrometric quality of both TGAS and HST . By contrast, comparison to ground-based measurements shows that some of those must have systematic errors exceeding the random errors. Our parallax estimates have uncertainties an order of magnitude larger than previous studies, but nevertheless imply distances consistent with previous estimates. By combining our PM measurements with literature positions, distances, and radial velocities, we measure Galactocentric space motions for the clusters and find that these also agree well with previous analyses. Our analysis provides a framework for determining more accurate distances and PMs of Galactic GCs using future Gaia data releases. This will provide crucial constraints on the near end of the cosmic distance ladder and provide accurate GC orbital histories.

  1. Damping of the domain walls motion in Co-based amorphous ribbons with helical magnetic anisotropy: Part III

    International Nuclear Information System (INIS)

    Zhmetko, D.N.; Zhmetko, S.D.

    2009-01-01

    The damping of the motion of domain walls of a sandwich domain structure by the eddy currents magnetic fields, the stray fields and the hysteresis friction fields is investigated. The blocking of the motion of domain walls by the eddy currents magnetic fields is discovered.

  2. Statistical Analysis of Conductor Motion in LHC Superconducting Dipole Magnets

    CERN Document Server

    Calvi, M; Pugnat, P; Siemko, A

    2004-01-01

    Premature training quenches are usually caused by the transient energy release within the magnet coil as it is energised. The dominant disturbances originate in cable motion and produce observable rapid variation in voltage signals called spikes. The experimental set up and the raw data treatment to detect these phenomena are briefly recalled. The statistical properties of different features of spikes are presented like for instance the maximal amplitude, the energy, the duration and the time correlation between events. The parameterisation of the mechanical activity of magnets is addressed. The mechanical activity of full-scale prototype and first preseries LHC dipole magnets is analysed and correlations with magnet manufacturing procedures and quench performance are established. The predictability of the quench occurrence is discussed and examples presented.

  3. Mass of the Local Group from Proper Motions of Distant Dwarf Galaxies

    Science.gov (United States)

    van der Marel, Roeland

    2010-09-01

    The Local Group and its two dominant spirals, the Milky Way and M31, have become the benchmark for testing many aspects of cosmological and galaxy formation theories, due to many exciting new discoveries in the past decade. However, it is difficult to put results in a proper cosmological context, because our knowledge of the mass M of the Local Group remains uncertain by a factor 4. In units of 10^{12} solar masses, a spherical infall model for the zero-velocity surface gives M 1.3; the sum of estimates for the Milky Way and M31 masses gives M 2.6; and the Local Group Timing argument for the M31 orbit gives M 5.6. It is possible to discriminate between the proposed masses by calculating the orbits of galaxies at the edge of the Local Group, which requires knowledge of transverse velocity components. We therefore propose to use ACS/WFC to determine the proper motions of the 4 dwarf galaxies near the edge of the Local Group {Cetus, Leo A, Tucana, Sag DIG} for which deep first epoch data {with 5-7 year time baselines} already exist in the HST Archive. Our team has extensive expertise with HST astrometric science, and our past/ongoing work for, e.g., Omega Cen, LMC/SMC and M31 show that the necessary astrometric accuracy is within the reach of HST's demonstrated capabilities. We have developed, tested, and published a new technique that uses compact background galaxies as astrometric reference sources, and we have already reduced the first epoch data. The final predicted transverse velocity accuracy, 36 km/s when averaged over the sample, will be sufficient to discriminate between each of the proposed Local Group masses at 2-sigma significance {4-sigma between the most extreme values}. Our project will yield the most accurate Local Group mass determination to date, and only HST can achieve the required accuracy.

  4. DIFFERENTIAL PROPER-MOTION MEASUREMENTS OF THE CYGNUS EGG NEBULA: THE PRESENCE OF EQUATORIAL OUTFLOWS

    Energy Technology Data Exchange (ETDEWEB)

    Ueta, Toshiya; Tomasino, Rachael L. [Department of Physics and Astronomy, MS 6900, University of Denver, Denver, CO 80208 (United States); Ferguson, Brian A. [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

    2013-08-01

    We present the results of differential proper-motion analyses of the Egg Nebula (RAFGL 2688, V1610 Cyg) based on the archived two-epoch optical data taken with the Hubble Space Telescope. First, we determined that the polarization characteristics of the Egg Nebula are influenced by the higher optical depth of the central regions of the nebula (i.e., the 'dustsphere' of {approx}10{sup 3} AU radius), causing the nebula to illuminate in two steps-the direct starlight is first channeled into bipolar cavities and then scattered off to the rest of the nebula. We then measured the amount of motion of local structures and the signature concentric arcs by determining their relative shifts over the 7.25 yr interval. Based on our analysis, which does not rely on the single-scattering assumption, we concluded that the lobes have been excavated by a linear expansion along the bipolar axis for the past {approx}400 yr, while the concentric arcs have been generated continuously and moving out radially at about 10 km s{sup -1} for the past {approx}5500 yr, and there appears to be a colatitudinally increasing trend in the radial expansion velocity field of the concentric arcs. Numerical investigations into the mass-loss modulation by the central binary system exist, which predict such a colatitudinally increasing expansion velocity field in the spiral-shock trails of the mass-loss ejecta. Therefore, the Egg Nebula may represent a rare edge-on case of the binary-modulated circumstellar environs, corroborating the previous theoretical predictions.

  5. The measurement of solar magnetic fields

    International Nuclear Information System (INIS)

    Stenflo, J.O.

    1978-01-01

    Solar activity is basically caused by the interaction between magnetic fields, solar rotation and convective motions. Detailed mapping of the Sun's rapidly varying magnetic field helps in the understanding of the mechanisms of solar activity. Observations in recent years have revealed unexpected and intriguing properties of solar magnetic fields, the explanation of which has become a challenge to plasma physicists. This review deals primarily with how the Sun's magnetic field is measured, but it also includes a brief review of the present observational picture of the magnetic field, which is needed to understand the problems of how to properly interpret the observations. 215 references. (author)

  6. Measurement of intrafractional prostate motion using magnetic resonance imaging

    International Nuclear Information System (INIS)

    Mah, Dennis; Freedman, Gary; Milestone, Bart; Hanlon, Alexandra; Palacio, Elizabeth; Richardson, Theresa; Movsas, Benjamin; Mitra, Raj; Horwitz, Eric; Hanks, Gerald E.

    2002-01-01

    Purpose: To quantify the three-dimensional intrafractional prostate motion over typical treatment time intervals with cine-magnetic resonance imaging (cine MRI) studies. Methods and Materials: Forty-two patients with prostate cancer were scanned supine in an alpha cradle cast using cine MRI. Twenty sequential slices were acquired in the sagittal and axial planes through the center of the prostate. Each scan took ∼9 min. The posterior, lateral, and superior edges of the prostate were tracked on each frame relative to the initial prostate position, and the size and duration of each displacement was recorded. Results: The prostate displacements were (mean ± SD): 0.2 ± 2.9 mm, 0.0 ± 3.4 mm, and 0.0 ± 1.5 mm in the anterior-posterior, superior-inferior, and medial-lateral dimensions respectively. The prostate motion appeared to have been driven by peristalsis in the rectum. Large displacements of the prostate (up to 1.2 cm) moved the prostate both anteriorly and superiorly and in some cases compressed the organ. For such motions, the prostate did not stay displaced, but moved back to its original position. To account for the dosimetric consequences of the motion, we also calculated the time-averaged displacement to be ∼1 mm. Conclusions: Cine MRI can be used to measure intrafractional prostate motion. Although intrafractional prostate motions occur, their effects are negligible compared to interfractional motion and setup error. No adjustment in margin is necessary for three-dimensional conformal or intensity-modulated radiation therapy

  7. Magnetized particle motion and acceleration around a Schwarzschild black hole in a magnetic field

    International Nuclear Information System (INIS)

    Abdujabbarov, Ahmadjon; Bobomurat Ahmedov; Rahimov, Ozodbek; Salikhbaev, Umar

    2014-01-01

    The capture cross section of magnetized particles with nonvanishing magnetic moment by a Schwarzschild black hole immersed in an asymptotically uniform magnetic field has been studied as an extension of the approach developed in Zakharov (1994 Class. Quantum Grav. 11 1027) for neutral unmagnetized particles in the Reissner–Nordström spacetime. The magnetic moment of the particle is chosen as in de Felice and Sorge (2003 Class. Quantum Grav. 20 469). It is shown that the spin of the particle sustains the stability of particles circularly orbiting around the black hole immersed in a magnetic field, i.e., a spinning particle's motion near the Schwarzschild black hole horizon is more stable than that of a particle with zero spin. It is shown that the magnetic parameter essentially changes the value of the critical angular momentum and affects the process of capture of the particles by the central black hole. Furthermore, the interaction between the magnetic moment of the particle and the magnetic field forces stable circular orbits to shift to the central object, and this effect should be taken into account in astrophysical scenarios related to the accretion discs and in measuring the spin of the black holes. The magnetized particle's acceleration mechanism near the black hole in an external magnetic field is studied. It is shown that due to the presence of a magnetic field, magnetized particles can accelerate to unlimited high energies. (paper)

  8. Drift Reduction in Pedestrian Navigation System by Exploiting Motion Constraints and Magnetic Field

    Directory of Open Access Journals (Sweden)

    Muhammad Ilyas

    2016-09-01

    Full Text Available Pedestrian navigation systems (PNS using foot-mounted MEMS inertial sensors use zero-velocity updates (ZUPTs to reduce drift in navigation solutions and estimate inertial sensor errors. However, it is well known that ZUPTs cannot reduce all errors, especially as heading error is not observable. Hence, the position estimates tend to drift and even cyclic ZUPTs are applied in updated steps of the Extended Kalman Filter (EKF. This urges the use of other motion constraints for pedestrian gait and any other valuable heading reduction information that is available. In this paper, we exploit two more motion constraints scenarios of pedestrian gait: (1 walking along straight paths; (2 standing still for a long time. It is observed that these motion constraints (called “virtual sensor”, though considerably reducing drift in PNS, still need an absolute heading reference. One common absolute heading estimation sensor is the magnetometer, which senses the Earth’s magnetic field and, hence, the true heading angle can be calculated. However, magnetometers are susceptible to magnetic distortions, especially in indoor environments. In this work, an algorithm, called magnetic anomaly detection (MAD and compensation is designed by incorporating only healthy magnetometer data in the EKF updating step, to reduce drift in zero-velocity updated INS. Experiments are conducted in GPS-denied and magnetically distorted environments to validate the proposed algorithms.

  9. 6% magnetic-field-induced strain by twin-boundary motion in ferromagnetic Ni-Mn-Ga

    International Nuclear Information System (INIS)

    Murray, S. J.; Marioni, M.; Allen, S. M.; O'Handley, R. C.; Lograsso, T. A.

    2000-01-01

    Field-induced strains of 6% are reported in ferromagnetic Ni-Mn-Ga martensites at room temperature. The strains are the result of twin boundary motion driven largely by the Zeeman energy difference across the twin boundary. The strain measured parallel to the applied magnetic field is negative in the sample/field geometry used here. The strain saturates in fields of order 400 kA/m and is blocked by a compressive stress of order 2 MPa applied orthogonal to the magnetic field. The strain versus field curves exhibit appreciable hysteresis associated with the motion of the twin boundaries. A simple model accounts quantitatively for the dependence of strain on magnetic field and external stress using as input parameters only measured quantities. (c) 2000 American Institute of Physics

  10. PARALLAXES AND PROPER MOTIONS OF ULTRACOOL BROWN DWARFS OF SPECTRAL TYPES Y AND LATE T

    International Nuclear Information System (INIS)

    Marsh, Kenneth A.; Kirkpatrick, J. Davy; Gelino, Christopher R.; Griffith, Roger L.; Wright, Edward L.; Cushing, Michael C.; Skrutskie, Michael F.; Eisenhardt, Peter R.

    2013-01-01

    We present astrometric measurements of 11 nearby ultracool brown dwarfs of spectral types Y and late-T, based on imaging observations from a variety of space-based and ground-based telescopes. These measurements have been used to estimate relative parallaxes and proper motions via maximum likelihood fitting of geometric model curves. To compensate for the modest statistical significance (∼ tan , assumed similar to that implied by previous observations of T dwarfs. Our estimated distances are therefore somewhat dependent on that assumption. Nevertheless, the results have yielded distances for five of our eight Y dwarfs and all three T dwarfs. Estimated distances in all cases are ∼> 3 pc. In addition, we have obtained significant estimates of V tan for two of the Y dwarfs; both are –1 , consistent with membership in the thin disk population. Comparison of absolute magnitudes with model predictions as a function of color shows that the Y dwarfs are significantly redder in J – H than predicted by a cloud-free model.

  11. The vacuum-arc plasma motion in a toroidal magnetic field

    International Nuclear Information System (INIS)

    Timoshenko, A.I.; Gnybida, M.V.; Taran, V.S.; Tereshin, V.I.; Chechelnitskij, O.G.

    2005-01-01

    The separation of the vacuum-arc plasma from macro-particles in the curvilinear plasma filters allows obtaining coatings with especially high characteristics. However, inside such filters the significant plasma losses also have been occurred. At the same time, increasing in the filter's efficiency is a difficult task without an effective mathematical model that really would describe the vacuum-arc plasma motion in a toroidal magnetic field. The description based on the flax-tube model was in fact only the first approximation in the decision of this problem. According to detailed flax-tube analysis of ions passage through the quarter torus plasma guide, the efficiency of the filter should grow up to 85% as the positive potential U, applied to the body of the plasma guide, is on the increase. However, the experiment showed that maximum of transparency reach up to ∼ 12%, at potential about of +18 Volts, and comes down under the further increase in potential. Such big digression from experiment does not justify the use of flux-tube model for designing of curvilinear plasma filters. We offer the new approach to the description of the vacuum-arc plasma motion in a toroidal magnetic field based on the solutions of steady-state (∂/∂t=0) Vlasov-Maxwell equations for the long plasma column aligned parallel to a constant axial magnetic field. The relations for the self-consistent electric polarization fields, which appear due to displacement of the electron component from ionic one on the curvilinear part of motion, were derived within a framework of the drift approximation. The dynamics of the central part of the plasma flow in the electric polarization fields was considered in detail. The displacement of the plasma flow at the output of the plasma guide was calculated for the carbon and titanium plasmas. The good agreement with the experimental data was obtained. (author)

  12. Universal current-velocity relation of skyrmion motion in chiral magnets

    Science.gov (United States)

    Iwasaki, Junichi; Mochizuki, Masahito; Nagaosa, Naoto

    2013-03-01

    Current-driven motion of the magnetic domain wall requires large critical current density jc ~109 -1012 A/m2, at which the joule heating is a serious problem. The skyrmions recently discovered in chiral magnets, on the other hand, have much smaller critical current of jc ~105 -106 A/m2. We present a numerical simulation of the Landau-Lifshitz-Gilbert equation, which reveals a remarkably robust and universal current-velocity relation of the slyrmion motion driven by the spin transfer torque unaffected by either impurities or nonadiabatic effect in sharp contrast to the case of domain wall or spin helix (HL). Simulation results are analyzed using a theory based on Thiele's equation, and it is concluded that this surprising behavior is due to the Magnus force and flexible shape-deformation of individual skyrmions and skyrmion crystal (SkX), which enable them to avoid pinning centers and then weaken the net pinning force. Dynamical deformation of SkX leads to the fluctuation of Bragg peak with large amplitude, which can be detected by the recent neutron-scattering experiment.

  13. Magnetic interactions, bonding, and motion of positive muons in magnetite

    International Nuclear Information System (INIS)

    Boekema, C.; Lichti, R.L.; Brabers, V.A.M.; Denison, A.B.; Cooke, D.W.; Heffner, R.H.; Hutson, R.L.; Leon, M.; Schillaci, M.E.

    1985-01-01

    Positive-muon behavior in magnetite is investigated by the muon-spin-rotation technique. The observed muon relaxation rate in zero applied field, in conjunction with the measured local field, allows us to separate muon-motion effects from phase transitions associated with magnetite. The local magnetic field is observed to be 4.02 kOe directed along the axis, the easy axis of magnetization. Possible origins of this field are discussed in terms which include local muon diffusion and a supertransfer hyperfine interaction resulting from muon-oxygen bonding. An anomaly in the muon hyperfine interactions is observed at 247 K

  14. Characterizing the Motion of Solar Magnetic Bright Points at High Resolution

    Science.gov (United States)

    Van Kooten, Samuel J.; Cranmer, Steven R.

    2017-11-01

    Magnetic bright points in the solar photosphere, visible in both continuum and G-band images, indicate footpoints of kilogauss magnetic flux tubes extending to the corona. The power spectrum of bright-point motion is thus also the power spectrum of Alfvén wave excitation, transporting energy up flux tubes into the corona. This spectrum is a key input in coronal and heliospheric models. We produce a power spectrum of bright-point motion using radiative magnetohydrodynamic simulations, exploiting spatial resolution higher than can be obtained in present-day observations, while using automated tracking to produce large data quantities. We find slightly higher amounts of power at all frequencies compared to observation-based spectra, while confirming the spectrum shape of recent observations. This also provides a prediction for observations of bright points with DKIST, which will achieve similar resolution and high sensitivity. We also find a granule size distribution in support of an observed two-population distribution, and we present results from tracking passive tracers, which show a similar power spectrum to that of bright points. Finally, we introduce a simplified, laminar model of granulation, with which we explore the roles of turbulence and of the properties of the granulation pattern in determining bright-point motion.

  15. A second-order approximation of particle motion in the fringing field of a dipole magnet

    International Nuclear Information System (INIS)

    Tarantin, N.I.

    1980-01-01

    The radial and axial motion of charged particles in the fringing field of an arbitrary dipole magnet has been considered with accuracy to the second-order of small quantities. The dipole magnet has an inhomogeneous field and oblique entrance and exit boundaries in the form of second-order curves. The region of the fringing field has a variable extension. A new definition of the effective boundary of the real fringing field has a variable extension. A new definition of the effective boundary of the real fringing field of the dipole magnet is used. A better understanding of the influence of the fringing magnetic field on the motion of charged particles in the pole gap of the dipole magnet has been obtained. In particular, it is shown that it is important to take into account, in the second approximation, some terms related formally to the next approximations. The results are presented in a form convenient for practical calculations. (orig.)

  16. Reduction of angular spread at nonadiabatic electron motion in magnetically insulated diode

    Energy Technology Data Exchange (ETDEWEB)

    Arzhannikov, A V; Sinitskij, S L [Institute of Nuclear Physics, Novosibirsk (Russian Federation)

    1997-12-31

    The behavior of the electron pitch-angle was investigated by analytical and numerical methods for the case of a magnetically insulated diode with a ribbon geometry. It is shown that at the boundary of the adiabaticity of the electron motion the angle can be multiply reduced by choice of a special inhomogeneity of the magnetic field. Analytic expressions for the final pitch-angle of the beam electrons are given. (author). 2 figs., 3 refs.

  17. An X-ray Expansion and Proper Motion Study of the Magellanic Cloud Supernova Remnant J0509-6731 with the Chandra X-ray Observatory

    Science.gov (United States)

    Roper, Quentin; Filipovi, Miroslav; Allen, Glenn E.; Sano, Hidetoshi; Park, Laurence; Pannuti, Thomas G.; Sasaki, Manami; Haberl, Frank; Kavanagh, Patrick J.; Yamane, Yumiko; Yoshiike, Satoshi; Fujii, Kosuke; Fukui, Yasuo; Seitenzahl, Ivo R.

    2018-05-01

    Using archival Chandra data consisting of a total of 78.46 ksec over two epochs seven years apart, we have measured the expansion of the young (˜400 years old) type Ia Large Magellanic Cloud supernova remnant (SNR) J0509-6731. In addition, we use radial brightness profile matching to detect proper-motion expansion of this SNR, and estimate an speed of 7 500±1 700 km s-1. This is one of the only proper motion studies of extragalactic SNRs expansion that is able to derive an expansion velocity, and one of only two such studies of an extragalactic SNR to yield positive results in the X-rays. We find that this expansion velocity is consistent with an optical expansion study on this object. In addition, we examine the medium into which the SNR is expanding by examining the CO and neutral H I gas using radio data obtained from Mopra, the Australia Telescope Compact Array and Parkes radio telescopes. We also briefly compare this result with a recent radio survey, and find that our results predict a radio spectral index α of -0.67±0.07. This value is consistent with high frequency radio observations of MCSNR J0509-6731.

  18. Evaluation of cardiac motion and function by cine magnetic resonance imaging

    International Nuclear Information System (INIS)

    Kondo, Takeshi; Kurokawa, Hiroshi; Anno, Hirofumi

    1992-01-01

    Cardiac cine magnetic resonance imaging (MRI) was studied to evaluate the cardiac motion and function, and a water-stream phantom study was performed to clarify whether it was possible to quantitatively assess the valvular regurgitation flow by the size of the flow void. In normal subjects, the left ventricular (LV) epicardial apex swung up to the base only a few millimeters, and the mitral annulus ring moved about 14 mm as mean value toward the apex during systole. Those motions of mitral annulus ring may contribute to the left atrial filling. The LV longitudinal shortening and torsions were shown by the tagging method. This tagging method was the best method for estimating cardiac motions. Cardiac cine MRI using software including a modified Simpson's method program and a wall motion analysis program was useful for routine LV volumetry and wall motion analysis because it was a simple and reliable method. Our water-stream phantom studies demonstrated that it might be difficult to perform quantitative evaluation of valvular regurgitation flow by using only the size of the flow void without acquiring information relating to the orifice area. (author)

  19. Adaptive bulk motion exclusion for improved robustness of abdominal magnetic resonance imaging

    NARCIS (Netherlands)

    Stemkens, Bjorn; Benkert, Thomas; Chandarana, Hersh; Bittman, Mark E.; Van den Berg, Cornelis A.T.; Lagendijk, Jan J.W.; Sodickson, Daniel K.; Tijssen, Rob H.N.; Block, Kai Tobias

    2017-01-01

    Non-Cartesian magnetic resonance imaging (MRI) sequences have shown great promise for abdominal examination during free breathing, but break down in the presence of bulk patient motion (i.e. voluntary or involuntary patient movement resulting in translation, rotation or elastic deformations of the

  20. Specific features of the motion of neutrons in a medium with a helical magnetic structure

    International Nuclear Information System (INIS)

    Fraerman, A. A.; Udalov, O. G.

    2007-01-01

    The specific features of the motion of neutrons in a noncoplanar magnetic field are considered by an example of the magnetization distribution in the form of a conical helix. The reflection coefficients of neutrons from holmium crystals are calculated. It is shown that, for a noncoplanar distribution of a magnetic field in a crystal, the reflection coefficient of neutrons with spin flip exhibits an additional feature

  1. Proper time axis of a closed relativistic system

    International Nuclear Information System (INIS)

    Chernikov, N.A.; Fadeev, N.G.; Shavokhina, N.S.

    1997-01-01

    The definition of a proper time axis of a closed relativistic system of colliding particles is given. The solution of the proper time axis problem is presented. If the light velocity c equals the imaginary unit i, then in the case of a plane motion of the system the problem about the proper time axis turns out to be equivalent to the known in engineering mechanics problem about the reduction of any system of forces, applied to a rigid body, to the dynamic screw. In the general case, when c=i, the problem about the proper time axis turns out to be equivalent to the problem about the reduction to the dynamic screw of a system of forces, applied to a rigid body in a four-dimensional Euclidean space

  2. Chaotic motion of a harmonically bound charged particle in a magnetic field, in the presence of a half-plane barrier

    NARCIS (Netherlands)

    Geurts, Bernardus J.; Wiegel, F.W.; Creswick, Richard J.

    1991-01-01

    The motion in the plane of an harmonically bound charged particle interacting with a magnetic field and a half-plane barrier along the positive x-axis is studied. The magnetic field is perpendicular to the plane in which the particle moves. This motion is integrable in between collisions of the

  3. Modelling of charged satellite motion in Earth's gravitational and magnetic fields

    Science.gov (United States)

    Abd El-Bar, S. E.; Abd El-Salam, F. A.

    2018-05-01

    In this work Lagrange's planetary equations for a charged satellite subjected to the Earth's gravitational and magnetic force fields are solved. The Earth's gravity, and magnetic and electric force components are obtained and expressed in terms of orbital elements. The variational equations of orbit with the considered model in Keplerian elements are derived. The solution of the problem in a fully analytical way is obtained. The temporal rate of changes of the orbital elements of the spacecraft are integrated via Lagrange's planetary equations and integrals of the normalized Keplerian motion obtained by Ahmed (Astron. J. 107(5):1900, 1994).

  4. Revised magnetic polarity time scale for the Paleocene and early Eocene and implications for Pacific plate motion

    International Nuclear Information System (INIS)

    Butler, R.F.; Coney, P.J.

    1981-01-01

    Magnetostratiographic studies of a continental sedimentary sequence in the Clark's Fork Basin, Wyoming and a marine sedimentary sequence at Gubbio, Italy indicate that the Paleocene--Eocene boundary occurs just stratigraphically above normal polarity zones correlative with magnetic anomaly 25 chron. These data indicate that the older boundary of anomaly 24 chron is 52.5 Ma. This age is younger than the late Paleocene age assigned by LaBrecque et al. [1977] and also younger than the basal Eocene age assigned by Ness et al. [1980]. A revised magnetic polarity time scale for the Paleocene and early Eocene is presented in this paper. Several changes in the relative motion system between the Pacific plate and neighboring plates occurred in the interval between anomaly 24 and anomaly 21. A major change in absolute motion of the Pacific plate is indicated by the bend in the Hawaiian--Emperor Seamount chain at approx.43 Ma. The revised magnetic polarity time scale indicates that the absolute motion change lags the relative motion changes by only approx.3--5 m.y. rather than by >10 m.y. as indicated by previous polarity time scales

  5. Variational Symplectic Integrator for Long-Time Simulations of the Guiding-Center Motion of Charged Particles in General Magnetic Fields

    International Nuclear Information System (INIS)

    Qin Hong; Guan Xiaoyin

    2008-01-01

    A variational symplectic integrator for the guiding-center motion of charged particles in general magnetic fields is developed for long-time simulation studies of magnetized plasmas. Instead of discretizing the differential equations of the guiding-center motion, the action of the guiding-center motion is discretized and minimized to obtain the iteration rules for advancing the dynamics. The variational symplectic integrator conserves exactly a discrete Lagrangian symplectic structure, and has better numerical properties over long integration time, compared with standard integrators, such as the standard and variable time-step fourth order Runge-Kutta methods

  6. Variational Symplectic Integrator for Long-Time Simulations of the Guiding-Center Motion of Charged Particles in General Magnetic Fields

    International Nuclear Information System (INIS)

    Qin, H.; Guan, X.

    2008-01-01

    A variational symplectic integrator for the guiding-center motion of charged particles in general magnetic fields is developed for long-time simulation studies of magnetized plasmas. Instead of discretizing the differential equations of the guiding-center motion, the action of the guiding-center motion is discretized and minimized to obtain the iteration rules for advancing the dynamics. The variational symplectic integrator conserves exactly a discrete Lagrangian symplectic structure, and has better numerical properties over long integration time, compared with standard integrators, such as the standard and variable time-step fourth order Runge-Kutta methods.

  7. Magnet fall inside a conductive pipe: motion and the role of the pipe wall thickness

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, G; Ladera, C L; Martin, P [Departamento de Fisica, Universidad Simon BolIvar, Apdo. 89000, Caracas 1080 (Venezuela, Bolivarian Republic of)], E-mail: clladera@usb.ve, E-mail: pmartin@usb.ve

    2009-07-15

    Theoretical models and experimental results are presented for the retarded fall of a strong magnet inside a vertical conductive non-magnetic tube. Predictions and experimental results are in good agreement modelling the magnet as a simple magnetic dipole. The effect of varying the pipe wall thickness on the retarding magnetic drag is studied for pipes of different materials. Conductive pipes of thinner walls produce less dragging force and the retarded fall of the magnet is seen to consist of an initial transient accelerated regime followed by a stage of uniform motion. Alternative models of the magnet field are also presented that improve the agreement between theory and experiments.

  8. Adiabatic, chaotic and quasi-adiabatic charged particle motion in two-dimensional magnetic field reversals

    International Nuclear Information System (INIS)

    Buechner, J.M.

    1989-01-01

    For a number of problems in the Plasma Astrophysics it is necessary to know the laws, which govern the non adiabatic charged particle dynamics in strongly curves magnetic field reversals. These are, e.q., the kinetic theory of the microscopic and macroscopicstability of current sheets in collionless plasma, of microturbulence, causing anomalous resistivity and dissipating currents, the problem of spontaneous reconnection, the formation of non Maxwellian distribution functions, particle acceleration and the use of particles as a diagnostic tool ('tracers'). To find such laws we derived from the differential equations of motion discrete mappings. These mappings allow an investigation of the motion after the break down of the adiabaticity of the magnetic moment. (author). 32 refs.; 5 figs.; 1 tab

  9. Statistical improvements in functional magnetic resonance imaging analyses produced by censoring high-motion data points.

    Science.gov (United States)

    Siegel, Joshua S; Power, Jonathan D; Dubis, Joseph W; Vogel, Alecia C; Church, Jessica A; Schlaggar, Bradley L; Petersen, Steven E

    2014-05-01

    Subject motion degrades the quality of task functional magnetic resonance imaging (fMRI) data. Here, we test two classes of methods to counteract the effects of motion in task fMRI data: (1) a variety of motion regressions and (2) motion censoring ("motion scrubbing"). In motion regression, various regressors based on realignment estimates were included as nuisance regressors in general linear model (GLM) estimation. In motion censoring, volumes in which head motion exceeded a threshold were withheld from GLM estimation. The effects of each method were explored in several task fMRI data sets and compared using indicators of data quality and signal-to-noise ratio. Motion censoring decreased variance in parameter estimates within- and across-subjects, reduced residual error in GLM estimation, and increased the magnitude of statistical effects. Motion censoring performed better than all forms of motion regression and also performed well across a variety of parameter spaces, in GLMs with assumed or unassumed response shapes. We conclude that motion censoring improves the quality of task fMRI data and can be a valuable processing step in studies involving populations with even mild amounts of head movement. Copyright © 2013 Wiley Periodicals, Inc.

  10. Motion and magnetic field structure of the Earth's magnetic tail near 30 R/sub E/

    International Nuclear Information System (INIS)

    Bowling, S.B.

    1975-01-01

    The analysis of data taken by the NASA-GSFC magnetometer experiment on the Explorer 34 spacecraft has shown that the diurnal wobble of the geomagnetic dipole axis measurably influences the position of the magnetotail near 30 R/sub E/ (earth radii). Viewed in the solar-ecliptic coordinate system, the dipole wobble resolves into components of motion perpendicular and parallel to the earth-sun line. The perpendicular component exerts a torque on the magnetotail and causes the neutral sheet (the midplane of the magnetotail) to pivot about an axis approximately parallel to the solar-wind flow direction. The parallel component encourages the neutral sheet to move above and below the solar-magnetospheric equatorial plane with an amplitude of 1 R/sub E/, as if the neutral sheet were hinged at a geocentric distance of 5.25 R/sub E/. The motion of the neutral sheet is also characterized by a random flapping in the solar-ecliptic Z-direction at a velocity of 100 km/sec and an amplitude of +- 2 R/sub E/. Results suggest the existence of a layer of nearly uniform cross-tail electric current that is about 2.3 R/sub E/ thick and envelops the neutral sheet. The magnetic field, whose average geometry resembles a flattened and extended dipole, gradually reverses direction within this current layer. The field is perpendicular to the neutral sheet where it has a value of 2 γ (1γ = 10 -5 Gauss). The analysis does not suggest a strong dependence of the magnetic-field configuration on the geomagnetic index Kp, although the field may intermittently disrupt into localized and short-lived magnetic loops during periods of enhanced geomagnetic activity

  11. Audiovisual Biofeedback Improves Cine–Magnetic Resonance Imaging Measured Lung Tumor Motion Consistency

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Danny [Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, Sidney, NSW (Australia); Greer, Peter B. [School of Mathematical and Physical Sciences, The University of Newcastle, Newcastle, NSW (Australia); Department of Radiation Oncology, Calvary Mater Newcastle, Newcastle, NSW (Australia); Ludbrook, Joanna; Arm, Jameen; Hunter, Perry [Department of Radiation Oncology, Calvary Mater Newcastle, Newcastle, NSW (Australia); Pollock, Sean; Makhija, Kuldeep; O' brien, Ricky T. [Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, Sidney, NSW (Australia); Kim, Taeho [Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, Sidney, NSW (Australia); Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia (United States); Keall, Paul, E-mail: paul.keall@sydney.edu.au [Radiation Physics Laboratory, Sydney Medical School, The University of Sydney, Sidney, NSW (Australia)

    2016-03-01

    Purpose: To assess the impact of an audiovisual (AV) biofeedback on intra- and interfraction tumor motion for lung cancer patients. Methods and Materials: Lung tumor motion was investigated in 9 lung cancer patients who underwent a breathing training session with AV biofeedback before 2 3T magnetic resonance imaging (MRI) sessions. The breathing training session was performed to allow patients to become familiar with AV biofeedback, which uses a guiding wave customized for each patient according to a reference breathing pattern. In the first MRI session (pretreatment), 2-dimensional cine-MR images with (1) free breathing (FB) and (2) AV biofeedback were obtained, and the second MRI session was repeated within 3-6 weeks (mid-treatment). Lung tumors were directly measured from cine-MR images using an auto-segmentation technique; the centroid and outlier motions of the lung tumors were measured from the segmented tumors. Free breathing and AV biofeedback were compared using several metrics: intra- and interfraction tumor motion consistency in displacement and period, and the outlier motion ratio. Results: Compared with FB, AV biofeedback improved intrafraction tumor motion consistency by 34% in displacement (P=.019) and by 73% in period (P<.001). Compared with FB, AV biofeedback improved interfraction tumor motion consistency by 42% in displacement (P<.046) and by 74% in period (P=.005). Compared with FB, AV biofeedback reduced the outlier motion ratio by 21% (P<.001). Conclusions: These results demonstrated that AV biofeedback significantly improved intra- and interfraction lung tumor motion consistency for lung cancer patients. These results demonstrate that AV biofeedback can facilitate consistent tumor motion, which is advantageous toward achieving more accurate medical imaging and radiation therapy procedures.

  12. Audiovisual Biofeedback Improves Cine–Magnetic Resonance Imaging Measured Lung Tumor Motion Consistency

    International Nuclear Information System (INIS)

    Lee, Danny; Greer, Peter B.; Ludbrook, Joanna; Arm, Jameen; Hunter, Perry; Pollock, Sean; Makhija, Kuldeep; O'brien, Ricky T.; Kim, Taeho; Keall, Paul

    2016-01-01

    Purpose: To assess the impact of an audiovisual (AV) biofeedback on intra- and interfraction tumor motion for lung cancer patients. Methods and Materials: Lung tumor motion was investigated in 9 lung cancer patients who underwent a breathing training session with AV biofeedback before 2 3T magnetic resonance imaging (MRI) sessions. The breathing training session was performed to allow patients to become familiar with AV biofeedback, which uses a guiding wave customized for each patient according to a reference breathing pattern. In the first MRI session (pretreatment), 2-dimensional cine-MR images with (1) free breathing (FB) and (2) AV biofeedback were obtained, and the second MRI session was repeated within 3-6 weeks (mid-treatment). Lung tumors were directly measured from cine-MR images using an auto-segmentation technique; the centroid and outlier motions of the lung tumors were measured from the segmented tumors. Free breathing and AV biofeedback were compared using several metrics: intra- and interfraction tumor motion consistency in displacement and period, and the outlier motion ratio. Results: Compared with FB, AV biofeedback improved intrafraction tumor motion consistency by 34% in displacement (P=.019) and by 73% in period (P<.001). Compared with FB, AV biofeedback improved interfraction tumor motion consistency by 42% in displacement (P<.046) and by 74% in period (P=.005). Compared with FB, AV biofeedback reduced the outlier motion ratio by 21% (P<.001). Conclusions: These results demonstrated that AV biofeedback significantly improved intra- and interfraction lung tumor motion consistency for lung cancer patients. These results demonstrate that AV biofeedback can facilitate consistent tumor motion, which is advantageous toward achieving more accurate medical imaging and radiation therapy procedures.

  13. Dealing with Magnetic Disturbances in Human Motion Capture: A Survey of Techniques

    Directory of Open Access Journals (Sweden)

    Gabriele Ligorio

    2016-03-01

    Full Text Available Magnetic-Inertial Measurement Units (MIMUs based on microelectromechanical (MEMS technologies are widespread in contexts such as human motion tracking. Although they present several advantages (lightweight, size, cost, their orientation estimation accuracy might be poor. Indoor magnetic disturbances represent one of the limiting factors for their accuracy, and, therefore, a variety of work was done to characterize and compensate them. In this paper, the main compensation strategies included within Kalman-based orientation estimators are surveyed and classified according to which degrees of freedom are affected by the magnetic data and to the magnetic disturbance rejection methods implemented. By selecting a representative method from each category, four algorithms were obtained and compared in two different magnetic environments: (1 small workspace with an active magnetic source; (2 large workspace without active magnetic sources. A wrist-worn MIMU was used to acquire data from a healthy subject, whereas a stereophotogrammetric system was adopted to obtain ground-truth data. The results suggested that the model-based approaches represent the best compromise between the two testbeds. This is particularly true when the magnetic data are prevented to affect the estimation of the angles with respect to the vertical direction.

  14. Stochastic electron dynamics due to drift waves in a sheared magnetic field and other drift motion problems

    International Nuclear Information System (INIS)

    Robertson, J.A.

    1986-12-01

    Electron motion in a single electrostatic wave in a sheared magnetic field is shown to become stochastic in the presence of a second wave at an amplitude well below that obtained from the overlapping pendulum resonance approximation. The enhanced stochasticity occurs for low parallel velocity electrons for which the parallel trapping motion from eE/sub parallel//m interacts strongly with the E x B trapping motion due to the presence of magnetic shear. The guiding-center equations for single particle electron orbits in given fields are investigated using both analytical and numerical techniques. The model assumes a slab magnetic field geometry with shear and two electrostatic plane waves propagating at an angle with respect to each other. Collisions and the self-consistent effect of the electron motion upon the fields are ignored. The guiding-center motion in an inertial reference frame moving in phase with the two waves is given by a two degree-of-freedom, autonomous Hamiltonian system. The single wave particle motion may be reduced to a two parameter family of one degree-of-freedom Hamiltonians which bifurcate from a pendulum phase space to a topology with three chains of elliptic and hyperbolic fixed points separated in radius about the mode-rational surface. In the presence of a perturbing wave with a different helicity, electrons in the small parallel velocity regime become stochastic at an amplitude scaling as the fourth root of the wave potential. The results obtained for stochastic motion apply directly to the problem of electron diffusion in drift waves occurring in toroidal fusion confinement devices. The effect of an adiabatically changing radial electric field upon guiding-center orbits in tokamaks is also investigated. This perturbation causes a radial polarization drift of trapped particle tokamak orbits

  15. OB Stars and Cepheids From the Gaia TGAS Catalogue: Test of their Distances and Proper Motions

    Directory of Open Access Journals (Sweden)

    Bobylev Vadim V.

    2017-12-01

    Full Text Available We consider young distant stars from the Gaia TGAS catalog. These are 250 classical Cepheids and 244 OB stars located at distances up to 4 kpc from the Sun. These stars are used to determine the Galactic rotation parameters using both trigonometric parallaxes and proper motions of the TGAS stars. In this case the considered stars have relative parallax errors less than 200%. Following the well-known statistical approach, we assume that the kinematic parameters found from the line-of-sight velocities Vr are less dependent on errors of distances than the found from the velocity components Vl. From values of the first derivative of the Galactic rotation angular velocity ′0, found from the analysis of velocities Vr and Vl separately, the scale factor of distances is determined.We found that from the sample of Cepheids the scale of distances of the TGAS should be reduced by 3%, and from the sample of OB stars, on the contrary, the scale should be increased by 9%.

  16. Spherical, rolling magnet generators for passive energy harvesting from human motion

    Science.gov (United States)

    Bowers, Benjamin J.; Arnold, David P.

    2009-09-01

    In this work, non-resonant, vibrational energy harvester architectures intended for human-motion energy scavenging are researched. The basic design employs a spherical, unidirectionally magnetized permanent magnet (NdFeB) ball that is allowed to move arbitrarily in a spherical cavity wrapped with copper coil windings. As the ball rotates and translates within the cage, the time-varying magnetic flux induces a voltage in the coil according to Faraday's Law. Devices ranging from 1.5 cm3 to 4 cm3 in size were tested under human activity scenarios—held in the user's hand or placed in the user's pocket while walking (4 km h-1) and running (14.5 km h-1). These harvesters have demonstrated rms voltages ranging from ~80 mV to 700 mV and time-averaged power densities up to 0.5 mW cm-3.

  17. GAIA: A WINDOW TO LARGE-SCALE MOTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Nusser, Adi [Physics Department and the Asher Space Science Institute-Technion, Haifa 32000 (Israel); Branchini, Enzo [Department of Physics, Universita Roma Tre, Via della Vasca Navale 84, 00146 Rome (Italy); Davis, Marc, E-mail: adi@physics.technion.ac.il, E-mail: branchin@fis.uniroma3.it, E-mail: mdavis@berkeley.edu [Departments of Astronomy and Physics, University of California, Berkeley, CA 94720 (United States)

    2012-08-10

    Using redshifts as a proxy for galaxy distances, estimates of the two-dimensional (2D) transverse peculiar velocities of distant galaxies could be obtained from future measurements of proper motions. We provide the mathematical framework for analyzing 2D transverse motions and show that they offer several advantages over traditional probes of large-scale motions. They are completely independent of any intrinsic relations between galaxy properties; hence, they are essentially free of selection biases. They are free from homogeneous and inhomogeneous Malmquist biases that typically plague distance indicator catalogs. They provide additional information to traditional probes that yield line-of-sight peculiar velocities only. Further, because of their 2D nature, fundamental questions regarding vorticity of large-scale flows can be addressed. Gaia, for example, is expected to provide proper motions of at least bright galaxies with high central surface brightness, making proper motions a likely contender for traditional probes based on current and future distance indicator measurements.

  18. Airfoil-based electromagnetic energy harvester containing parallel array motion between moving coil and multi-pole magnets towards enhanced power density.

    Science.gov (United States)

    Leung, Chung Ming; Wang, Ya; Chen, Wusi

    2016-11-01

    In this letter, the airfoil-based electromagnetic energy harvester containing parallel array motion between moving coil and trajectory matching multi-pole magnets was investigated. The magnets were aligned in an alternatively magnetized formation of 6 magnets to explore enhanced power density. In particular, the magnet array was positioned in parallel to the trajectory of the tip coil within its tip deflection span. The finite element simulations of the magnetic flux density and induced voltages at an open circuit condition were studied to find the maximum number of alternatively magnetized magnets that was required for the proposed energy harvester. Experimental results showed that the energy harvester with a pair of 6 alternatively magnetized linear magnet arrays was able to generate an induced voltage (V o ) of 20 V, with an open circuit condition, and 475 mW, under a 30 Ω optimal resistance load operating with the wind speed (U) at 7 m/s and a natural bending frequency of 3.54 Hz. Compared to the traditional electromagnetic energy harvester with a single magnet moving through a coil, the proposed energy harvester, containing multi-pole magnets and parallel array motion, enables the moving coil to accumulate a stronger magnetic flux in each period of the swinging motion. In addition to the comparison made with the airfoil-based piezoelectric energy harvester of the same size, our proposed electromagnetic energy harvester generates 11 times more power output, which is more suitable for high-power-density energy harvesting applications at regions with low environmental frequency.

  19. Identifications and limited spectroscopy for Luyten common proper motion stars with probable white dwarf components. I - Pair brighter than 17th magnitude

    Science.gov (United States)

    Oswalt, Terry D.; Hintzen, Paul M.; Luyten, Willem J.

    1988-01-01

    Identifications are provided for 103 bright Luyten common proper motion (CPM) stellar systems with m(pg) less than 17.0 mag containing likely white dwarf (WD) components. New spectral types are presented for 55 components, and spectral types for 51 more are available in the literature. With the CPM systems previously published by Giclas et al. (1978), the Luyten stars provide a uniform sample of nearly 200 pairs or multiples brighter than 17h magnitude. Selection effects biasing the combined samples are discussed; in particular, evidence is presented that fewer than 1 percent of wide WD binaries have been detected.

  20. Finger-tapping motion analysis in cervical myelopathy by magnetic-sensor tapping device.

    Science.gov (United States)

    Miwa, Toshitada; Hosono, Noboru; Mukai, Yoshihiro; Makino, Takahiro; Kandori, Akihiko; Fuji, Takeshi

    2013-08-01

    Case-control study. The purpose of this study is to determine finger motion of patients with cervical myelopathy during finger-tapping cycles. A major symptom of patients with compressive cervical myelopathy is finger clumsiness. Therefore, understanding finger motion is prerequisite in assessing the severity of myelopathy. The popular grip-and-release test evaluates only the number of motion cycles, which is insufficient to fully describe complex finger motion. Forty-three patients with cervical myelopathy and 41 healthy controls tapped their index fingers against their thumbs as rapidly as possible for 30 seconds and the motion was recorded by a magnetic-sensor coil attached to the nail surface. Output signals were stored in a computer, which automatically calculated tapping frequency, distance moved, ratio of opening/closing velocity and the SD of the tapping interval. The SD of the tapping interval was significantly greater and all other measures were significantly smaller in patients with cervical myelopathy, than in healthy controls. All indices significantly improved after surgical decompression of the cervical spine. Distance moved (Pearson correlation coefficient: r=0.590, Ptapping interval (r=-0.451; P=0.002) were significantly correlated with the Japanese Orthopedic Association score (neurological scale). The quantitative evaluation of finger paralysis was performed by this tapping device. Speed and regularity in repetitive motion of fingers were correlated with the severity of cervical myelopathy.

  1. N-body modeling of globular clusters: detecting intermediate-mass black holes by non-equipartition in HST proper motions

    Science.gov (United States)

    Trenti, Michele

    2010-09-01

    Intermediate Mass Black Holes {IMBHs} are objects of considerable astrophysical significance. They have been invoked as possible remnants of Population III stars, precursors of supermassive black holes, sources of ultra-luminous X-ray emission, and emitters of gravitational waves. The centers of globular clusters, where they may have formed through runaway collapse of massive stars, may be our best chance of detecting them. HST studies of velocity dispersions have provided tentative evidence, but the measurements are difficult and the results have been disputed. It is thus important to explore and develop additional indicators of the presence of an IMBH in these systems. In a Cycle 16 theory project we focused on the fingerprints of an IMBH derived from HST photometry. We showed that an IMBH leads to a detectable quenching of mass segregation. Analysis of HST-ACS data for NGC 2298 validated the method, and ruled out an IMBH of more than 300 solar masses. We propose here to extend the search for IMBH signatures from photometry to kinematics. The velocity dispersion of stars in collisionally relaxed stellar systems such as globular clusters scales with main sequence mass as sigma m^alpha. A value alpha = -0.5 corresponds to equipartition. Mass-dependent kinematics can now be measured from HST proper motion studies {e.g., alpha = -0.21 for Omega Cen}. Preliminary analysis shows that the value of alpha can be used as indicator of the presence of an IMBH. In fact, the quenching of mass segregation is a result of the degree of equipartition that the system attains. However, detailed numerical simulations are required to quantify this. Therefore we propose {a} to carry out a new, larger set of realistic N-body simulations of star clusters with IMBHs, primordial binaries and stellar evolution to predict in detail the expected kinematic signatures and {b} to compare these predictions to datasets that are {becoming} available. Considerable HST resources have been invested in

  2. Field driven magnetic racetrack memory accompanied with the interfacial Dzyaloshinskii-Moriya interaction

    Science.gov (United States)

    Kim, June-Seo; Lee, Hyeon-Jun; Hong, Jung-Il; You, Chun-Yeol

    2018-06-01

    The in-plane magnetic field pulse driven domain wall motion on a perpendicularly magnetized nanowire is numerically investigated by performing micromagnetic simulations and magnetic domain wall dynamics are evaluated analytically with one-dimensional collective coordinate models including the interfacial Dzyaloshinskii-Moriya interaction. With the action of the precession torque, the chirality and the magnetic field direction dependent displacements of the magnetic domain walls are clearly observed. In order to move Bloch type and Neel type domain walls, a longitudinal and a transverse in-plane magnetic field pulse are required, respectively. The domain wall type (Bloch or Neel) can easily be determined by the dynamic motion of the domain walls under the applied pulse fields. By applying a temporally asymmetric in-plane field pulse and successive notches in the perpendicularly magnetized nanowire strip line with a proper interval, the concept of racetrack memory based on the synchronous displacements of the chirality dependent multiple domain walls is verified to be feasible. Requirement of multiple domain walls with homogeneous chirality is achieved with the help of Dzyaloshinskii-Moriya interaction.

  3. Assessment of Bladder Motion for Clinical Radiotherapy Practice Using Cine-Magnetic Resonance Imaging

    International Nuclear Information System (INIS)

    McBain, Catherine A.; Khoo, Vincent S.; Buckley, David L.; Sykes, Jonathan S.; Green, Melanie M.; Cowan, Richard A.; Hutchinson, Charles E.; Moore, Christopher J.; Price, Patricia M.

    2009-01-01

    Purpose: Organ motion is recognized as the principal source of inaccuracy in bladder radiotherapy (RT), but there is currently little information on intrafraction bladder motion. Methods and Materials: We used cine-magnetic resonance imaging (cine-MRI) to study bladder motion relevant to intrafraction RT delivery. On two occasions, a 28 minute cine-MRI sequence was acquired from 10 bladder cancer patients and 5 control participants immediately after bladder emptying, after abstinence from drinking for the preceding hour. From the resulting cine sequences, bladder motion was subjectively assessed. To quantify bladder motion, the bladder was contoured in imaging volume sets at 0, 14, and 28 min to measure changes to bladder volumes, wall displacements, and center of gravity (COG) over time. Results: The dominant source of bladder motion during imaging was bladder filling (up to 101% volume increase); rectal and small bowel movements were transient, with minimal impact. Bladder volume changes were similar for all participants. However for bladder cancer patients, wall displacements were larger (up to 58 mm), less symmetrical, and more variable compared with nondiseased control bladders. Conclusions: Significant and individualized intrafraction bladder wall displacements may occur during bladder RT delivery. This important source of inaccuracy should be incorporated into treatment planning and verification.

  4. Fractional Langevin Equation Model for Characterization of Anomalous Brownian Motion from NMR Signals

    Science.gov (United States)

    Lisý, Vladimír; Tóthová, Jana

    2018-02-01

    Nuclear magnetic resonance is often used to study random motion of spins in different systems. In the long-time limit the current mathematical description of the experiments allows proper interpretation of measurements of normal and anomalous diffusion. The shorter-time dynamics is however correctly considered only in a few works that do not go beyond the standard Langevin theory of the Brownian motion (BM). In the present work, the attenuation function S (t) for an ensemble of spins in a magnetic-field gradient, expressed in a form applicable for any kind of stationary stochastic dynamics of spins with or without a memory, is calculated in the frame of the model of fractional BM. The solution of the model for particles trapped in a harmonic potential is obtained in a simple way and used for the calculation of S (t). In the limit of free particles coupled to a fractal heat bath, the results compare favorably with experiments acquired in human neuronal tissues.

  5. Analysis of 3-D Tongue Motion from Tagged and Cine Magnetic Resonance Images

    Science.gov (United States)

    Xing, Fangxu; Woo, Jonghye; Lee, Junghoon; Murano, Emi Z.; Stone, Maureen; Prince, Jerry L.

    2016-01-01

    Purpose: Measuring tongue deformation and internal muscle motion during speech has been a challenging task because the tongue deforms in 3 dimensions, contains interdigitated muscles, and is largely hidden within the vocal tract. In this article, a new method is proposed to analyze tagged and cine magnetic resonance images of the tongue during…

  6. Collective coordinate models of domain wall motion in perpendicularly magnetized systems under the spin hall effect and longitudinal fields

    Energy Technology Data Exchange (ETDEWEB)

    Nasseri, S. Ali, E-mail: ali.nasseri@isi.it [ISI Foundation - Via Alassio 11/c –10126 Torino (Italy); Politecnico di Torino - Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Moretti, Simone; Martinez, Eduardo [University of Salamanca - Cardenal Plá y Deniel, 22, 37008 Salamanca (Spain); Serpico, Claudio [ISI Foundation - Via Alassio 11/c –10126 Torino (Italy); University of Naples Federico II - Via Claudio 21, 80125 Napoli (Italy); Durin, Gianfranco [ISI Foundation - Via Alassio 11/c –10126 Torino (Italy); Istituto Nazionale di Ricerca Metrologica (INRIM) - Strada delle Cacce 91, 10135 Torino (Italy)

    2017-03-15

    Recent studies on heterostructures of ultrathin ferromagnets sandwiched between a heavy metal layer and an oxide have highlighted the importance of spin-orbit coupling (SOC) and broken inversion symmetry in domain wall (DW) motion. Specifically, chiral DWs are stabilized in these systems due to the Dzyaloshinskii-Moriya interaction (DMI). SOC can also lead to enhanced current induced DW motion, with the Spin Hall effect (SHE) suggested as the dominant mechanism for this observation. The efficiency of SHE driven DW motion depends on the internal magnetic structure of the DW, which could be controlled using externally applied longitudinal in-plane fields. In this work, micromagnetic simulations and collective coordinate models are used to study current-driven DW motion under longitudinal in-plane fields in perpendicularly magnetized samples with strong DMI. Several extended collective coordinate models are developed to reproduce the micromagnetic results. While these extended models show improvements over traditional models of this kind, there are still discrepancies between them and micromagnetic simulations which require further work. - Highlights: • Moving DWs in PMA material maintain their structure under longitudinal in-plane fields. • As a result of longitudinal fields, magnetization in the domains becomes canted. • A critical longitudinal field was identified and correlated with the DMI strength. • A canted collective coordinate model was developed for DW motion under in-plane fields.

  7. On a magnetic source of southward motion of the AMPTE solar wind barium release of 27 December 1984

    International Nuclear Information System (INIS)

    Dunlop, M.W.; Southwood, D.J.; Mier-Jedrzejowicz, W.A.C.

    1987-01-01

    We re-examine the magnetic field measurements from the Ba + ion release, made as part of the international AMPTE space programme on 27 December 1984. Observations from the Earth showed that the initial motion of the ion cloud was southward (-ZETAsub(GSE)). Examination of the magnetic field structure at the two spacecraft in the vicinity of the release indicates that there was a net southward force acting during the period immediately preceding the motion. We show that the force was adequate to accelerate the cloud in the southward direction. We demonstrate that the operation of a magnetic stress in such a way is consistent with some other features of the interaction. It is proposed that the momentum acquired by the core of the cloud in this process is balanced by ions accelerated northward by opposite magnetic stresses which are on the flanks (in Y sub(GSE))

  8. Biocompatible KMnF3 nanoparticular contrast agent with proper plasma retention time for in vivo magnetic resonance imaging.

    Science.gov (United States)

    Liu, Zhi-jun; Song, Xiao-xia; Xu, Xian-zhu; Tang, Qun

    2014-04-18

    Nanoparticular MRI contrast agents are rapidly becoming suitable for use in clinical diagnosis. An ideal nanoparticular contrast agent should be endowed with high relaxivity, biocompatibility, proper plasma retention time, and tissue-specific or tumor-targeting imaging. Herein we introduce PEGylated KMnF3 nanoparticles as a new type of T1 contrast agent. Studies showed that the nanoparticular contrast agent revealed high bio-stability with bovine serum albumin in PBS buffer solution, and presented excellent biocompatibility (low cytotoxicity, undetectable hemolysis and hemagglutination). Meanwhile the new contrast agent possessed proper plasma retention time (circulation half-life t1/2 is approximately 2 h) in the body of the administrated mice. It can be delivered into brain vessels and maintained there for hours, and is mostly cleared from the body within 48 h, as demonstrated by time-resolved MRI and Mn-biodistribution analysis. Those distinguishing features make it suitable to obtain contrast-enhanced brain magnetic resonance angiography. Moreover, through the process of passive targeting delivery, the T1 contrast agent clearly illuminates a brain tumor (glioma) with high contrast image and defined shape. This study demonstrates that PEGylated KMnF3 nanoparticles represent a promising biocompatible vascular contrast agent for magnetic resonance angiography and can potentially be further developed into an active targeted tumor MRI contrast agent.

  9. Diagnostics of vector magnetic fields

    Science.gov (United States)

    Stenflo, J. O.

    1985-01-01

    It is shown that the vector magnetic fields derived from observations with a filter magnetograph will be severely distorted if the spatially unresolved magnetic structure is not properly accounted for. Thus the apparent vector field will appear much more horizontal than it really is, but this distortion is strongly dependent on the area factor and the temperature line weakenings. As the available fluxtube models are not sufficiently well determined, it is not possible to correct the filter magnetograph observations for these effects in a reliable way, although a crude correction is of course much better than no correction at all. The solution to this diagnostic problem is to observe simultaneously in suitable combinations of spectral lines, and/or use Stokes line profiles recorded with very high spectral resolution. The diagnostic power of using a Fourier transform spectrometer for polarimetry is shown and some results from I and V spectra are illustrated. The line asymmetries caused by mass motions inside the fluxtubes adds an extra complication to the diagnostic problem, in particular as there are indications that the motions are nonstationary in nature. The temperature structure appears to be a function of fluxtube diameter, as a clear difference between plage and network fluxtubes was revealed. The divergence of the magnetic field with height plays an essential role in the explanation of the Stokes V asymmetries (in combination with the mass motions). A self consistent treatment of the subarcsec field geometry may be required to allow an accurate derivation of the spatially averaged vector magnetic field from spectrally resolved data.

  10. Simple motion correction strategy reduces respiratory-induced motion artifacts for k-t accelerated and compressed-sensing cardiovascular magnetic resonance perfusion imaging.

    Science.gov (United States)

    Zhou, Ruixi; Huang, Wei; Yang, Yang; Chen, Xiao; Weller, Daniel S; Kramer, Christopher M; Kozerke, Sebastian; Salerno, Michael

    2018-02-01

    Cardiovascular magnetic resonance (CMR) stress perfusion imaging provides important diagnostic and prognostic information in coronary artery disease (CAD). Current clinical sequences have limited temporal and/or spatial resolution, and incomplete heart coverage. Techniques such as k-t principal component analysis (PCA) or k-t sparcity and low rank structure (SLR), which rely on the high degree of spatiotemporal correlation in first-pass perfusion data, can significantly accelerate image acquisition mitigating these problems. However, in the presence of respiratory motion, these techniques can suffer from significant degradation of image quality. A number of techniques based on non-rigid registration have been developed. However, to first approximation, breathing motion predominantly results in rigid motion of the heart. To this end, a simple robust motion correction strategy is proposed for k-t accelerated and compressed sensing (CS) perfusion imaging. A simple respiratory motion compensation (MC) strategy for k-t accelerated and compressed-sensing CMR perfusion imaging to selectively correct respiratory motion of the heart was implemented based on linear k-space phase shifts derived from rigid motion registration of a region-of-interest (ROI) encompassing the heart. A variable density Poisson disk acquisition strategy was used to minimize coherent aliasing in the presence of respiratory motion, and images were reconstructed using k-t PCA and k-t SLR with or without motion correction. The strategy was evaluated in a CMR-extended cardiac torso digital (XCAT) phantom and in prospectively acquired first-pass perfusion studies in 12 subjects undergoing clinically ordered CMR studies. Phantom studies were assessed using the Structural Similarity Index (SSIM) and Root Mean Square Error (RMSE). In patient studies, image quality was scored in a blinded fashion by two experienced cardiologists. In the phantom experiments, images reconstructed with the MC strategy had higher

  11. Semi-automated vectorial analysis of anorectal motion by magnetic resonance defecography in healthy subjects and fecal incontinence.

    Science.gov (United States)

    Noelting, J; Bharucha, A E; Lake, D S; Manduca, A; Fletcher, J G; Riederer, S J; Joseph Melton, L; Zinsmeister, A R

    2012-10-01

    Inter-observer variability limits the reproducibility of pelvic floor motion measured by magnetic resonance imaging (MRI). Our aim was to develop a semi-automated program measuring pelvic floor motion in a reproducible and refined manner. Pelvic floor anatomy and motion during voluntary contraction (squeeze) and rectal evacuation were assessed by MRI in 64 women with fecal incontinence (FI) and 64 age-matched controls. A radiologist measured anorectal angles and anorectal junction motion. A semi-automated program did the same and also dissected anorectal motion into perpendicular vectors representing the puborectalis and other pelvic floor muscles, assessed the pubococcygeal angle, and evaluated pelvic rotation. Manual and semi-automated measurements of anorectal junction motion (r = 0.70; P controls. This semi-automated program provides a reproducible, efficient, and refined analysis of pelvic floor motion by MRI. Puborectalis injury is independently associated with impaired motion of puborectalis, not other pelvic floor muscles in controls and women with FI. © 2012 Blackwell Publishing Ltd.

  12. Magnetic field pitch angle diagnostic using the motional Stark effect (invited)

    International Nuclear Information System (INIS)

    Levinton, F.M.; Gammel, G.M.; Kaita, R.; Kugel, H.W.; Roberts, D.W.

    1990-01-01

    The Stark effect has been employed in a novel technique for obtaining the pitch angle profile and q(r) using polarimetry measurements of the Doppler shifted H α emission from a hydrogen diagnostic neutral beam. As a neutral beam propagates through a plasma, collisions of the beam particles with the background ions and electrons will excite beam atoms, leading to emission of radiation. The motional Stark effect, which arises from the electric field induced in the atom's rest frame due to the beam motion across the magnetic field (E=V beam xB), causes a wavelength splitting of several angstroms and polarization of the emitted radiation. The Δm=±1 transitions, or σ components, from the beam fluorescence are linearly polarized parallel to the direction of the local magnetic field when viewed transverse to the fields. Since the hydrogen beam provides good spatial localization and penetration, the pitch angle can be obtained anywhere in the plasma. A photoelastic modulator (PEM) is used to modulate the linearly polarized light. Depending on the orientation of the PEM, it can measure the sine or cosine of the angle of polarization. Two PEM's are used to measure both components simultaneously. Results of q(r) for both Ohmic and NBI heated discharges have been obtained in the Princeton Beta Experiment (PBX-M) tokamak, with an uncertainty of ∼6% for q(0)

  13. Enhancement of spin Hall effect induced torques for current-driven magnetic domain wall motion: Inner interface effect

    KAUST Repository

    Bang, Do; Yu, Jiawei; Qiu, Xuepeng; Wang, Yi; Awano, Hiroyuki; Manchon, Aurelien; Yang, Hyunsoo

    2016-01-01

    We investigate the current-induced domain wall motion in perpendicular magnetized Tb/Co wires with structure inversion asymmetry and different layered structures. We find that the critical current density to drive domain wall motion strongly depends on the layered structure. The lowest critical current density ∼15MA/cm2 and the highest slope of domain wall velocity curve are obtained for the wire having thin Co sublayers and more inner Tb/Co interfaces, while the largest critical current density ∼26MA/cm2 required to drive domain walls is observed in the Tb-Co alloy magnetic wire. It is found that the Co/Tb interface contributes negligibly to Dzyaloshinskii-Moriya interaction, while the effective spin-orbit torque strongly depends on the number of Tb/Co inner interfaces (n). An enhancement of the antidamping torques by extrinsic spin Hall effect due to Tb rare-earth impurity-induced skew scattering is suggested to explain the high efficiency of current-induced domain wall motion.

  14. Enhancement of spin Hall effect induced torques for current-driven magnetic domain wall motion: Inner interface effect

    KAUST Repository

    Bang, Do

    2016-05-23

    We investigate the current-induced domain wall motion in perpendicular magnetized Tb/Co wires with structure inversion asymmetry and different layered structures. We find that the critical current density to drive domain wall motion strongly depends on the layered structure. The lowest critical current density ∼15MA/cm2 and the highest slope of domain wall velocity curve are obtained for the wire having thin Co sublayers and more inner Tb/Co interfaces, while the largest critical current density ∼26MA/cm2 required to drive domain walls is observed in the Tb-Co alloy magnetic wire. It is found that the Co/Tb interface contributes negligibly to Dzyaloshinskii-Moriya interaction, while the effective spin-orbit torque strongly depends on the number of Tb/Co inner interfaces (n). An enhancement of the antidamping torques by extrinsic spin Hall effect due to Tb rare-earth impurity-induced skew scattering is suggested to explain the high efficiency of current-induced domain wall motion.

  15. Measures and Relative Motions of Some Mostly F. G. W. Struve Doubles

    Science.gov (United States)

    Wiley, E. O.

    2012-04-01

    Measures of 59 pairs of double stars with long observational histories using "lucky imaging" techniques are reported. Relative motions of 59 pairs are investigated using histories of observation, scatter plots of relative motion, ordinary least-squares (OLS) and total proper motion analyses performed in "R," an open source programming language. A scatter plot of the coefficient of determinations derived from the OLS y|epoch and OLS x|epoch clearly separates common proper motion pairs from optical pairs and what are termed "long-period binary candidates." Differences in proper motion separate optical pairs from long-term binary candidates. An Appendix is provided that details how to use known rectilinear pairs as calibration pairs for the program REDUC.

  16. Magnetic navigation system for the precise helical and translational motions of a microrobot in human blood vessels

    Science.gov (United States)

    Jeon, S. M.; Jang, G. H.; Choi, H. C.; Park, S. H.; Park, J. O.

    2012-04-01

    Different magnetic navigation systems (MNSs) have been investigated for the wireless manipulation of microrobots in human blood vessels. Here we propose a MNS and methodology for generation of both the precise helical and translational motions of a microrobot to improve its maneuverability in complex human blood vessel. We then present experiments demonstrating the helical and translational motions of a spiral-type microrobot to verify the proposed MNS.

  17. Flux motion in Y-Ba-Cu-O bulk superconductors during pulse field magnetization

    International Nuclear Information System (INIS)

    Yoshizawa, K; Nariki, S; Sakai, N; Murakami, M; Hirabayasi, I; Takizawa, T

    2004-01-01

    We have studied the relationship between the magnetization and temperature change in Y-Ba-Cu-O bulk superconductor during pulse field magnetization (PFM). The flux motion was monitored using both Hall sensors and pick-up coils that are placed on a surface of a Y-Ba-Cu-O disc having dimensions of 15 mm in diameter and 0.95 mm in thickness. The peak value of the field was varied from 0.2 to 0.8 T. The effect of the static bias field was also studied in the range of 0-3 T. The temperature of the sample surface was measured using a resistance temperature sensor. The temperature increased with the magnitude of the applied pulsed magnetic field, and the amount of temperature rise decreased with increasing static bias field

  18. A Review of Point-Wise Motion Tracking Algorithms for Fetal Magnetic Resonance Imaging.

    Science.gov (United States)

    Chikop, Shivaprasad; Koulagi, Girish; Kumbara, Ankita; Geethanath, Sairam

    2016-01-01

    We review recent feature-based tracking algorithms as applied to fetal magnetic resonance imaging (MRI). Motion in fetal MRI is an active and challenging area of research, but the challenge can be mitigated by strategies related to patient setup, acquisition, reconstruction, and image processing. We focus on fetal motion correction through methods based on tracking algorithms for registration of slices with similar anatomy in multiple volumes. We describe five motion detection algorithms based on corner detection and region-based methods through pseudocodes, illustrating the results of their application to fetal MRI. We compare the performance of these methods on the basis of error in registration and minimum number of feature points required for registration. Harris, a corner detection method, provides similar error when compared to the other methods and has the lowest number of feature points required at that error level. We do not discuss group-wise methods here. Finally, we attempt to communicate the application of available feature extraction methods to fetal MRI.

  19. The precise adjustment of coil location for transcranial magnetic stimulation during dynamic motion.

    Science.gov (United States)

    Kitamura, Taku; Yaeshima, Katsutoshi; Yamamoto, Shin-Ichiro; Kawashima, Noritaka

    2013-01-01

    Transcranial magnetic stimulation (TMS) to the cerebral cortex is a major in vitro technique that is used in the field of neurophysiology. The magnitude of the motor-evoked potentials (MEP) that are elicited by TMS to the primary motor cortex reflect the excitability of the corticospinal pathway. MEPs are very sensitive to the scalp location of the stimulus coil, especially when corticospinal excitability is recorded during walking or other dynamic motions. In this study, we created a coil navigational system that consisted of three-dimensional motion analysis cameras, rigid bodies on the head and coil, and programming software. In order to evaluate the feasibility of the use of our system, pseudo TMS was applied during treadmill walking with or without the navigational system. As a result, we found that the variances due to coil location and/or distance from the target site were reduced with our system. This technique enabled us to realize high precision and accuracy in coil placement, even during dynamic motion.

  20. Investigation of domain wall motion in RE-TM magnetic wire towards a current driven memory and logic

    Energy Technology Data Exchange (ETDEWEB)

    Awano, Hiroyuki

    2015-06-01

    Current driven magnetic domain wall (DW) motions of ferri-magnetic TbFeCo wires have been investigated. In the case of a Si substrate, the critical current density (Jc) of DW motion was successfully reduced to 3×10{sup 6} A/cm{sup 2}. Moreover, by using a polycarbonate (PC) substrate with a molding groove of 600 nm width, the Jc was decreased to 6×10{sup 5} A/cm{sup 2}. In order to fabricate a logic in memory, a current driven spin logics (AND, OR, NOT) have been proposed and successfully demonstrated under the condition of low Jc. These results indicate that TbFeCo nanowire is an excellent candidate for next generation power saving memory and logic.

  1. Individual particle motion and the effect of scattering in an axially symmetric magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Garren, A; Riddell, R J; Smith, L; Henrich, L R [Radiation Laboratory, University of California, Berkeley, CA (United States); Bing, G; Northrop, T G; Roberts, J E [Radiation Laboratory, University of California, Livermore, CA (United States)

    1958-07-01

    The possibility of confining charged particles with magnetic mirrors has long been recognized. A mirror field has axial symmetry and a magnitude that increases along the axis away from a central region in which the particles are to be contained. Heretofore, the likelihood of confinement has been based on the approximate invariance of the magnetic moment as described by Alfven. If the magnetic moment of a particle with given energy is too small the particle escapes axially through the mirror. The moment can become small because it is not a rigorous constant of the motion or because of Coulomb scattering of the particle. Both these effects have been studied; the first by analytic and numerical methods and the second by numerical solution of the Fokker- Planck equation.

  2. Orbit-averaged quantities, the classical Hellmann-Feynman theorem, and the magnetic flux enclosed by gyro-motion

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, R. J., E-mail: rperkins@pppl.gov; Bellan, P. M. [Applied Physics and Materials Science, California Institute of Technology, Pasadena, California 91125 (United States)

    2015-02-15

    Action integrals are often used to average a system over fast oscillations and obtain reduced dynamics. It is not surprising, then, that action integrals play a central role in the Hellmann-Feynman theorem of classical mechanics, which furnishes the values of certain quantities averaged over one period of rapid oscillation. This paper revisits the classical Hellmann-Feynman theorem, rederiving it in connection to an analogous theorem involving the time-averaged evolution of canonical coordinates. We then apply a modified version of the Hellmann-Feynman theorem to obtain a new result: the magnetic flux enclosed by one period of gyro-motion of a charged particle in a non-uniform magnetic field. These results further demonstrate the utility of the action integral in regards to obtaining orbit-averaged quantities and the usefulness of this formalism in characterizing charged particle motion.

  3. On the dynamics aspects for the plane motion of a particle under the action of potential forces in the presence of a magnetic field

    Science.gov (United States)

    Mnasri, C.; Elmandouh, A. A.

    2018-06-01

    This article deals with the general motion of a particle moving in the Euclidean plane under the influence of a conservative potential force in the presence of a magnetic field perpendicular to the plane of the motion. We introduce the conditions for which this motion is not algebraically integrable by using Kowalevski's exponents. We present the equilibrium positions and study their stability and moreover, we clarify that the existence of the magnetic field acts as a stabilizer for maximum unstable equilibrium points for the effective potential. We employ Lyapunov theorem to construct the periodic solutions near the equilibrium points. The allowed regions of motion are specified and illustrated graphically.

  4. CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS

    International Nuclear Information System (INIS)

    Muirhead, Philip S.; Johnson, John Asher; Morton, Timothy D.; Pineda, John Sebastian; Bottom, Michael; Crepp, Justin R.; Kirby, Evan N.; Apps, Kevin; Carter, Joshua A.; Fabrycky, Daniel C.; Hamren, Katherine; Rojas-Ayala, Bárbara; Schlawin, Everett; Covey, Kevin R.; Stassun, Keivan G.; Pepper, Joshua; Hebb, Leslie; Howard, Andrew W.; Isaacson, Howard T.; Marcy, Geoffrey W.

    2012-01-01

    We characterize the star KOI 961, an M dwarf with transit signals indicative of three short-period exoplanets discovered by the Kepler mission. We proceed by comparing KOI 961 to Barnard's Star, a nearby, well-characterized mid-M dwarf. We compare colors, optical and near-infrared spectra, and find remarkable agreement between the two, implying similar effective temperatures and metallicities. Both are metal-poor compared to the Solar neighborhood, have low projected rotational velocity, high absolute radial velocity, large proper motion, and no quiescent Hα emission—all of which are consistent with being old M dwarfs. We combine empirical measurements of Barnard's Star and expectations from evolutionary isochrones to estimate KOI 961's mass (0.13 ± 0.05 M ☉ ), radius (0.17 ± 0.04 R ☉ ), and luminosity (2.40 × 10 –3.0±0.3 L ☉ ). We calculate KOI 961's distance (38.7 ± 6.3 pc) and space motions, which, like Barnard's Star, are consistent with a high scale-height population in the Milky Way. We perform an independent multi-transit fit to the public Kepler light curve and significantly revise the transit parameters for the three planets. We calculate the false-positive probability for each planet candidate, and find a less than 1% chance that any one of the transiting signals is due to a background or hierarchical eclipsing binary, validating the planetary nature of the transits. The best-fitting radii for all three planets are less than 1 R ⊕ , with KOI 961.03 being Mars-sized (R P = 0.57 ± 0.18 R ⊕ ), and they represent some of the smallest exoplanets detected to date.

  5. Two-dimensional convection and interchange motions in fluids and magnetized plasmas

    DEFF Research Database (Denmark)

    Garcia, O.E.; Bian, N.H.; Naulin, V.

    2006-01-01

    fluids, emphasizing its relation to interchange motions of non- uniformly magnetized plasmas. This is followed by a review of the theories for the onset of convection and quasi-linear saturation in driven-dissipative systems. Non-linear numerical simulations which result in stationary convective states...... behaviour of the fluctuation level which is associated with relaxation oscillations in the kinetic energy of the azimuthally mean flows. This leads to a state of large-scale intermittency manifested by exponential tails in the single-point probability distribution function of the dependent variables...

  6. Measurement of the poloidal magnetic field in the PBX-M tokamak using the motional Stark effect

    International Nuclear Information System (INIS)

    Levinton, F.M.; Fonck, R.J.; Gammel, G.M.; Kaita, R.; Kugel, H.W.; Powell, E.T.; Roberts, D.W.

    1989-05-01

    Polarimetry measurements of the Doppler-shifted H/sub α/ emission from a hydrogen neutral beam on the PBX-M tokamak have been employed in a novel technique for obtaining q(0) and poloidal magnetic field profiles. The electric field from the beam particle motion across the magnetic field (E = V/sub beam/ /times/ B) causes a wavelength splitting of several angstroms, and polarization of the emitted radiation (Stark effect). Viewed transverse to the fields, the emission is linearly polarized with the angle of polarization related to the direction of the magnetic field. 14 refs., 5 figs

  7. Motion-Corrected Real-Time Cine Magnetic Resonance Imaging of the Heart: Initial Clinical Experience.

    Science.gov (United States)

    Rahsepar, Amir Ali; Saybasili, Haris; Ghasemiesfe, Ahmadreza; Dolan, Ryan S; Shehata, Monda L; Botelho, Marcos P; Markl, Michael; Spottiswoode, Bruce; Collins, Jeremy D; Carr, James C

    2018-01-01

    Free-breathing real-time (RT) imaging can be used in patients with difficulty in breath-holding; however, RT cine imaging typically experiences poor image quality compared with segmented cine imaging because of low resolution. Here, we validate a novel unsupervised motion-corrected (MOCO) reconstruction technique for free-breathing RT cardiac images, called MOCO-RT. Motion-corrected RT uses elastic image registration to generate a single heartbeat of high-quality data from a free-breathing RT acquisition. Segmented balanced steady-state free precession (bSSFP) cine images and free-breathing RT images (Cartesian, TGRAPPA factor 4) were acquired with the same spatial/temporal resolution in 40 patients using clinical 1.5 T magnetic resonance scanners. The respiratory cycle was estimated using the reconstructed RT images, and nonrigid unsupervised motion correction was applied to eliminate breathing motion. Conventional segmented RT and MOCO-RT single-heartbeat cine images were analyzed to evaluate left ventricular (LV) function and volume measurements. Two radiologists scored images for overall image quality, artifact, noise, and wall motion abnormalities. Intraclass correlation coefficient was used to assess the reliability of MOCO-RT measurement. Intraclass correlation coefficient showed excellent reliability (intraclass correlation coefficient ≥ 0.95) of MOCO-RT with segmented cine in measuring LV function, mass, and volume. Comparison of the qualitative ratings indicated comparable image quality for MOCO-RT (4.80 ± 0.35) with segmented cine (4.45 ± 0.88, P = 0.215) and significantly higher than conventional RT techniques (3.51 ± 0.41, P cine (1.51 ± 0.90, P = 0.088 and 1.23 ± 0.45, P = 0.182) were not different. Wall motion abnormality ratings were comparable among different techniques (P = 0.96). The MOCO-RT technique can be used to process conventional free-breathing RT cine images and provides comparable quantitative assessment of LV function and volume

  8. Localized Models of Charged Particle Motion in Martian Crustal Magnetic Cusps

    Science.gov (United States)

    Brain, D. A.; Poppe, A. R.; Jarvinen, R.; Dong, Y.; Egan, H. L.; Fang, X.

    2017-12-01

    The induced magnetosphere of Mars is punctuated by localized but strong crustal magnetic fields that are observed to play host to a variety of phenomena typically associated with global magnetic fields, such as auroral processes and particle precipitation, field-aligned current systems, and ion outflow. Each of these phenomena occur on the night side, in small-scale magnetic `cusp' regions of vertically aligned field. Cusp regions are not yet capable of being spatially resolved in global scale models that include the ion kinetics necessary for simulating charged particle transport along cusps. Local models are therefore necessary if we are to understand how cusp processes operate at Mars. Here we present the first results of an effort to model the kinetic particle motion and electric fields in Martian cusps. We are adapting both a 1.5D Particle-in-Cell (PIC) model for lunar magnetic cusps regions to the Martian case and a hybrid model framework (used previously for the global Martian plasma interaction and for lunar magnetic anomaly regions) to cusps in 2D. By comparing the models we can asses the importance of electron kinetics in particle transport along cusp field lines. In this first stage of our study we model a moderately strong nightside cusp, with incident hot hydrogen plasma from above, and cold planetary (oxygen) plasma entering the simulation from below. We report on the spatial and temporal distribution of plasma along cusp field lines for this initial case.

  9. Percussive drilling application of translational motion permanent magnet machine

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shujun

    2012-07-01

    It is clear that percussive drills are very promising since they can increase the rate of penetration in hard rock formations. Any small improvements on the percussive drills can make a big contribution to lowering the drilling costs since drilling a well for the oil and gas industry is very costly. This thesis presents a percussive drilling system mainly driven by a tubular reciprocating translational motion permanent magnet synchronous motor (RTPMSM), which efficiently converts electric energy to kinetic energy for crushing the hard rock since there is no mechanical media. The thesis starts from state-of-the-art of percussive drilling techniques, reciprocating translational motion motors, and self-sensing control of electric motors and its implementation issues. The following chapters present modeling the hard rock, modeling the drill, the design issues of the drill, the RTPMSM and its control. A single-phase RTPMSM prototype is tested for the hard rock drilling. The presented variable voltage variable frequency control is also validated on it. The space vector control and self-sensing control are also explored on a three-phase RTPMSM prototype. The results show that the percussive drill can be implemented to the hard rock drilling applications. A detailed summarisation of contributions and future work is presented at the end of the thesis.(Author)

  10. Asteroid proper elements from an analytical second order theory

    International Nuclear Information System (INIS)

    Knezevic, Z.; Milani, A.

    1989-01-01

    The authors have computed by a fully analytical method a new set of proper elements for 3322 numbered main-belt asteroids. They are presented in the following format: asteroid number, proper semimajor axis (AU), proper eccentricity, sine of proper inclination and quality code (see below). This new set is significantly more accurate than all the previous ones at low to moderate eccentricities and inclinations, and especially near the main mean-motion resonances (e.g., the Themis region). This is because the short periodic perturbations are rigorously removed, and the main effects of the second-order (containing the square of the ratio [the mass of Jupiter/mass of the Sun]) are accounted for. Effects arising from the terms in the Hamiltonian of degree up to four in the eccentricity and inclination of both the asteroid and Jupiter are taken into account, and the fundamental frequencies g (for the perihelion) and s(for the node) of the asteroid are computed with a interative algorithm consistent with the basic results of modern dynamics (e.g., Kolmogorov-Arnold-Moser theory)

  11. New High Proper Motion Stars from the Digitized Sky Survey. II. Northern Stars with 0.5" yr-1 < μ < 2.0" yr-1 at High Galactic Latitudes

    Science.gov (United States)

    Lépine, Sébastien; Shara, Michael M.; Rich, R. Michael

    2003-08-01

    In a continuation of our systematic search for high proper motion stars in the Digitized Sky Survey, we have completed the analysis of northern sky fields at Galactic latitudes above 25°. With the help of our SUPERBLINK software, a powerful automated blink comparator developed by us, we have identified 1146 stars in the magnitude range 8data mining of the Digitized Sky Survey, developed and operated by the Catalogs and Surveys Branch of the Space Telescope Science Institute, Baltimore.

  12. NMR signals within the generalized Langevin model for fractional Brownian motion

    Science.gov (United States)

    Lisý, Vladimír; Tóthová, Jana

    2018-03-01

    The methods of Nuclear Magnetic Resonance belong to the best developed and often used tools for studying random motion of particles in different systems, including soft biological tissues. In the long-time limit the current mathematical description of the experiments allows proper interpretation of measurements of normal and anomalous diffusion. The shorter-time dynamics is however correctly considered only in a few works that do not go beyond the standard memoryless Langevin description of the Brownian motion (BM). In the present work, the attenuation function S (t) for an ensemble of spin-bearing particles in a magnetic-field gradient, expressed in a form applicable for any kind of stationary stochastic dynamics of spins with or without a memory, is calculated in the frame of the model of fractional BM. The solution of the model for particles trapped in a harmonic potential is obtained in an exceedingly simple way and used for the calculation of S (t). In the limit of free particles coupled to a fractal heat bath, the results compare favorably with experiments acquired in human neuronal tissues. The effect of the trap is demonstrated by introducing a simple model for the generalized diffusion coefficient of the particle.

  13. Regular and chaotic motion of two dimensional electrons in a strong magnetic field

    International Nuclear Information System (INIS)

    Bar-Lev, Oded; Levit, Shimon.

    1992-05-01

    For two dimensional system of electrons in a strong magnetic field a standard approximation is the projection on a single Landau level. The resulting Hamiltonian is commonly treated semiclassically. An important element in applying the semiclassical approximation is the integrability of the corresponding classical system. We discuss the relevant integrability conditions and give a simple example of a non-integrable system-two interacting electrons in the presence of two impurities-which exhibits a coexistence of regular and chaotic classical motions. Since the inverse of the magnetic field plays the role of the Planck constant in these problems, one has the opportunity to control the 'closeness' of chaotic physical systems to the classical limit. (author)

  14. Magnetic guns with cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, David; Beleggia, Marco; Heller, Luděk

    2012-01-01

    The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...... of the magnetostatic interaction energy. For comparison, the forces involved are also calculated numerically using finite elements methods. Based on the conservation of the magnetostatic and kinetic energies, the exit and asymptotic velocities are determined. The derived formulas can be used to optimize the generated...... forces and motion of the inner cylindrical magnet....

  15. Real-Time Cosmology with Gaia: Developing the Theory to Use Extragalactic Proper Motions to Make Dynamical Cosmological Tests, to Measure Geometric Distances, and to Detect Primordial Gravitational Waves

    Science.gov (United States)

    Darling, Jeremy

    A new field of study, "real-time cosmology," is now possible. This involves observing a dynamic universe that can be seen to change over human timescales. Most cosmological observations are geometrical, using standard candles or rulers to measure the expansion history and curvature as light propagates through the universe. Real-time cosmological measurements are dynamical, revealing the changing geometry of the universe - thus often providing geometrical distances independent of the canonical cosmological distance ladder - and are typically orthogonal to customary cosmological tests. This field of inquiry is no longer far-fetched, and this proposal demonstrates using extant data that many types of measurement are now within a factor of a few of being detectable, but the theory will very soon lag the observational capabilities. The Gaia mission will provide astrometry and proper motions of roughly 100 microarcseconds per year for half a million quasars by the end of its 5-year mission, but the theory for how to employ these data for cosmological tests has not been established. This project will develop the theory, models, and methods needed to make optimal use of the Gaia extragalactic proper motion measurements and to make significant new cosmological tests, distance measurements, and mass measurements. Gaia data can provide rich cosmological tests that are nearly model-independent. This work will build the theoretical framework enabling Gaia to measure or constrain: (1) The real-time growth and recession of structures, providing mass and distance measurements, (2) Extragalactic parallax for a statistical sample and individual galaxies, thus providing geometric distances, (3) The primordial stochastic long-period gravitational wave background, which deflects quasar light in a quadrupolar proper motion pattern, and (4) Cosmic shear, rotation, bulk motion, and local voids that may manifest as an apparent acceleration attributed to dark energy. One can also test the

  16. X-Ray Analysis of the Proper Motion and Pulsar Wind Nebula for PSR J1741-2054

    Science.gov (United States)

    Auchettl, Katie; Slane, Patrick; Romani, Roger W.; Posselt, Bettina; Pavlov, George G.; Kargaltsev, Oleg; Ng, C-Y.; Temim, Tea; Weisskopf, Martin C.; Bykov, Andrei; hide

    2015-01-01

    We obtained six observations of PSR J1741-2054 using the Chandra ACIS-S detector totaling approx.300 ks. By registering this new epoch of observations to an archival observation taken 3.2 yr earlier using X-ray point sources in the field of view, we have measured the pulsar proper motion at micron = 109 +/- 10 mas yr(exp. -1) in a direction consistent with the symmetry axis of the observed H(alpha) nebula. We investigated the inferred past trajectory of the pulsar but find no compelling association with OB associations in which the progenitor may have originated. We confirm previous measurements of the pulsar spectrum as an absorbed power law with photon index gamma = 2.68 +/- 0.04, plus a blackbody with an emission radius of (4.5(+3.2/-2.5))d(0.38) km, for a DM-estimated distance of 0.38d(0.38) kpc and a temperature of 61.7 +/- 3.0 eV. Emission from the compact nebula is well described by an absorbed power law model with a photon index of gamma = 1.67 +/- 0.06, while the diffuse emission seen as a trail extending northeast of the pulsar shows no evidence of synchrotron cooling. We also applied image deconvolution techniques to search for small-scale structures in the immediate vicinity of the pulsar, but found no conclusive evidence for such structures.

  17. What motion is: William Neile and the laws of motion.

    Science.gov (United States)

    Kemeny, Max

    2017-07-01

    In 1668-1669 William Neile and John Wallis engaged in a protracted correspondence regarding the nature of motion. Neile was unhappy with the laws of motion that had been established by the Royal Society in three papers published in 1668, deeming them not explanations of motion at all, but mere descriptions. Neile insisted that science could not be informative without a discussion of causes, meaning that Wallis's purely kinematic account of collision could not be complete. Wallis, however, did not consider Neile's objections to his work to be serious. Rather than engage in a discussion of the proper place of natural philosophy in science, Wallis decided to show how Neile's preferred treatment of motion lead to absurd conclusions. This dispute is offered as a case study of dispute resolution within the early Royal Society.

  18. The Role of Viscosity in Causing the Plasma Poloidal Motion in Magnetic Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Ake; Wang, Yuming; Liu, Jiajia; Zhou, Zhenjun; Shen, Chenglong; Liu, Rui; Zhuang, Bin; Zhang, Quanhao, E-mail: ymwang@ustc.edu.cn [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2017-08-20

    An interesting phenomenon, plasma poloidal motion, has been found in many magnetic clouds (MCs), and viscosity has been proposed as a possible mechanism. However, it is not clear how significant the role of viscosity is in generating such motion. In this paper, we conduct a statistical study of the MCs detected by the Wind spacecraft during 1995–2012. It is found that, for 19% of all the studied MCs (186), the poloidal velocities of the MC plasma near the MC boundaries are well correlated with those of the corresponding ambient solar wind plasma. A non-monotonic increase from inner to outer MCs suggests that the viscosity does play a role, albeit weak, on the poloidal motion in the MC statistically. The possible dependence on the solar wind parameters is then studied in detail for the nine selected crossings, which represent the viscosity characteristic. There is an evident negative correlation between the viscosity and the density, a weak negative correlation between the viscosity and the turbulence strength, and no clear correlation between the viscosity and the temperature.

  19. Geometric size effect on the extrinsic Gilbert damping in laterally confined magnetic structures

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hyon-Seok [Department of Emerging Materials Science, DGIST, Daegu 42988 (Korea, Republic of); Lee, Kyeong-Dong [Department of Materials Science and Engineering, KAIST, Daejeon 34141 (Korea, Republic of); You, Chun-Yeol [Department of Physics, Inha University, Incheon 22212 (Korea, Republic of); Park, Byong-Guk [Department of Materials Science and Engineering, KAIST, Daejeon 34141 (Korea, Republic of); Hong, Jung-Il, E-mail: jihong@dgist.ac.kr [Department of Emerging Materials Science, DGIST, Daegu 42988 (Korea, Republic of); Research Centre for Emerging Materials, DGIST, Daegu 42988 (Korea, Republic of)

    2016-05-15

    We investigated spin dynamics in micron-length scale patterned thin films using the GPU-based micromagnetic simulation program. Spin precessional motion was induced by a Gaussian-pulse magnetic field. The effective Gilbert damping was examined by tracking the precessional motion of the spins, and we found that the damping constant depends on the size and shape of the pattern as well as the externally applied magnetic field. Additional extrinsic damping generated around the edge region was attributed to the dephasing effect between the fundamental spin wave and other spin wave modes. We find that the effect of extrinsic damping could be eliminated by proper adjustments of sample size, external bias field, position, and area of observation. - Highlights: • GPU based micromagnetic simulation of spin dynamics in the micropatterned ferromagnetic films. • Effect of edge regions of the pattern on the Gilbert damping behaviors. • Guide for the analyses of intrinsic magnetic damping in the micron scale patterned films.

  20. Energy-imbalance mechanism of domain wall motion induced by propagation spin waves in finite magnetic nanostripe

    International Nuclear Information System (INIS)

    Zhu, Jinrong; Han, Zhaoyan; Su, Yuanchang; Hu, Jingguo

    2014-01-01

    The mechanism of the domain wall (DW) motions induced by spin wave in finite magnetic nanostripe is studied by micromagnetic simulations. We find that the spin-wave induced DM motions are always accompanied by an energy imbalance between two sides of the DW. The DW motion can be attributed to the expansion of the low-energy-density area and the contraction of the high-energy-density area. The energy imbalance strongly depends on whether the spin wave passes through the DW or is reflected by the DW. In the area of the spin wave propagation, the energy density increases with the time. However, in the superposition area of the incident spin wave and the reflected spin wave, the energy density decreases with the increasing of the time. It shows that this energy imbalance can be controlled by tuning the frequency of the spin wave. Finally, the effect of the damping parameter value is discussed. - Highlights: • The mechanism of the spin-wave induced DW motions is studied. • The spin-wave induced DW motions and the energy imbalance mechanism are given. • The DW motion with the same direction to that of SW is explained. • The DW motion with the opposite direction to that of SW is explained

  1. A four-dimensional motion field atlas of the tongue from tagged and cine magnetic resonance imaging

    Science.gov (United States)

    Xing, Fangxu; Prince, Jerry L.; Stone, Maureen; Wedeen, Van J.; El Fakhri, Georges; Woo, Jonghye

    2017-02-01

    Representation of human tongue motion using three-dimensional vector fields over time can be used to better understand tongue function during speech, swallowing, and other lingual behaviors. To characterize the inter-subject variability of the tongue's shape and motion of a population carrying out one of these functions it is desirable to build a statistical model of the four-dimensional (4D) tongue. In this paper, we propose a method to construct a spatio-temporal atlas of tongue motion using magnetic resonance (MR) images acquired from fourteen healthy human subjects. First, cine MR images revealing the anatomical features of the tongue are used to construct a 4D intensity image atlas. Second, tagged MR images acquired to capture internal motion are used to compute a dense motion field at each time frame using a phase-based motion tracking method. Third, motion fields from each subject are pulled back to the cine atlas space using the deformation fields computed during the cine atlas construction. Finally, a spatio-temporal motion field atlas is created to show a sequence of mean motion fields and their inter-subject variation. The quality of the atlas was evaluated by deforming cine images in the atlas space. Comparison between deformed and original cine images showed high correspondence. The proposed method provides a quantitative representation to observe the commonality and variability of the tongue motion field for the first time, and shows potential in evaluation of common properties such as strains and other tensors based on motion fields.

  2. Cluster magnetic field observations of the bowshock: Orientation, motion and structure

    Directory of Open Access Journals (Sweden)

    T. S. Horbury

    Full Text Available Four spacecraft Cluster magnetic field observations of the low quasi-perpendicular terrestrial bowshock are presented for the first time. Multiple quasi-perpendicular crossings on 25 December 2000 are analysed. By combining data from the four spacecraft, bowshock orientations and velocities can be calculated. It is shown that, even while in rapid motion, the bowshock normal direction remains remarkably constant, and that coplanarity estimates are accurate to, typically, around 20°. Magnetic field magnitude profiles are shown to be very well correlated between spacecraft although downstream waves with fluctuations perpendicular to the local field, while statistically similar at all four spacecraft, are poorly correlated on separation scales of several hundred km. Examples are shown of a number of bowshock phenomena, including non-standing fluctuations in the shock foot and the shock interacting with changing solar wind conditions.

    Key words. Interplanetary physics (planetary bow shocks Space plasma physics (shock waves; waves and instabilities

  3. Cluster magnetic field observations of the bowshock: Orientation, motion and structure

    Directory of Open Access Journals (Sweden)

    T. S. Horbury

    2001-09-01

    Full Text Available Four spacecraft Cluster magnetic field observations of the low quasi-perpendicular terrestrial bowshock are presented for the first time. Multiple quasi-perpendicular crossings on 25 December 2000 are analysed. By combining data from the four spacecraft, bowshock orientations and velocities can be calculated. It is shown that, even while in rapid motion, the bowshock normal direction remains remarkably constant, and that coplanarity estimates are accurate to, typically, around 20°. Magnetic field magnitude profiles are shown to be very well correlated between spacecraft although downstream waves with fluctuations perpendicular to the local field, while statistically similar at all four spacecraft, are poorly correlated on separation scales of several hundred km. Examples are shown of a number of bowshock phenomena, including non-standing fluctuations in the shock foot and the shock interacting with changing solar wind conditions.Key words. Interplanetary physics (planetary bow shocks Space plasma physics (shock waves; waves and instabilities

  4. Design Optimization of a Magnetically Levitated Electromagnetic Vibration Energy Harvester for Body Motion

    Science.gov (United States)

    Pancharoen, K.; Zhu, D.; Beeby, S. P.

    2016-11-01

    This paper presents a magnetically levitated electromagnetic vibration energy harvester based on magnet arrays. It has a nonlinear response that extends the operating bandwidth and enhances the power output of the harvesting device. The harvester is designed to be embedded in a hip prosthesis and harvest energy from low frequency movements (< 5 Hz) associated with human motion. The design optimization is performed using Comsol simulation considering the constraints on size of the harvester and low operating frequency. The output voltage across the optimal load 3.5kΩ generated from hip movement is 0.137 Volts during walking and 0.38 Volts during running. The power output harvested from hip movement during walking and running is 5.35 μW and 41.36 μW respectively..

  5. A nuclear magnetic relaxation study on internal motion of polyelectrolytes in solution

    International Nuclear Information System (INIS)

    Schriever, J.

    1977-01-01

    The aim of this thesis is to investigate the significance and the amount of information which can be extracted from the study of frequency dependence of magnetic relaxation rates in solutions of a synthetic macromolecule. Solutions of poly(methacrylic acid), PMA, in water were chosen as the object of the present work. A short survey of nuclear magnetic relaxation in solutions of simple macromolecules is presented. Results obtained by continuous wave experiments on PMA solutions are shown (viz. the information about the transverse relaxation from line width analysis of 60 MHz proton spectra). Water enriched in 17 O is used in magnetic relaxation studies; the results of the determination of hydrogen lifetimes in aqueous solutions of acetic acid and poly(methacrylic acid) are given. The possibility of obtaining information about the dynamics of deuterons in the acid side groups of weak polyacids by measuring deuteron relaxation in heavy water solutions of those acids is considered. The use of deuteron relaxation rate experiments on solutions of selectively methylene deuterated poly(methacrylic acid), [-CD 2 -CCH 3 COOH-]n, is demonstrated and the backbone methylene C-atom motion is charachterized. The magne-tic relaxation of nuclei in the side groups of methylene deuterated PMA, viz. protons in the methyland deuterons in the acid side groups is presented

  6. SLoWPoKES-II: 100,000 WIDE BINARIES IDENTIFIED IN SDSS WITHOUT PROPER MOTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Dhital, Saurav [Department of Physical Sciences, Embry-Riddle Aeronautical University, 600 South Clyde Morris Blvd., Daytona Beach, FL 32114 (United States); West, Andrew A.; Schluns, Kyle J.; Massey, Angela P. [Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215 (United States); Stassun, Keivan G., E-mail: dhitals@erau.edu [Department of Physics and Astronomy, Vanderbilt University, 6301 Stevenson Center, Nashville, TN, 37235 (United States)

    2015-08-15

    We present the Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES)-II catalog of low-mass visual binaries identified from the Sloan Digital Sky Survey (SDSS) by matching photometric distances. The candidate pairs are vetted by comparing the stellar information. The candidate pairs are vetted by comparing the stellar density at their respective Galactic positions to Monte Carlo realizations of a simulated Milky Way. In this way, we are able to identify large numbers of bona fide wide binaries without the need for proper motions. Here, 105,537 visual binaries with angular separations of ∼1–20″ were identified, each with a probability of chance alignment of ≤5%. This is the largest catalog of bona fide wide binaries to date, and it contains a diversity of systems—in mass, mass ratios, binary separations, metallicity, and evolutionary states—that should facilitate follow-up studies to characterize the properties of M dwarfs and white dwarfs. There is a subtle but definitive suggestion of multiple populations in the physical separation distribution, supporting earlier findings. We suggest that wide binaries are composed of multiple populations, most likely representing different formation modes. There are 141 M7 or later wide binary candidates, representing a seven-fold increase over the number currently known. These binaries are too wide to have been formed via the ejection mechanism. Finally, we found that 6% of spectroscopically confirmed M dwarfs are not included in the SDSS STAR catalog; they are misclassified as extended sources due to the presence of a nearby or partially resolved companion. The SLoWPoKES-II catalog is publicly available to the entire community on the World Wide Web via the Filtergraph data visualization portal.

  7. Domain Wall Motion in Magnetic Nanostrips under the Influence of Rashba Field

    Directory of Open Access Journals (Sweden)

    Vito Puliafito

    2012-01-01

    Full Text Available Spin-orbit Rashba effect applies a torque on the magnetization of a ferromagnetic nanostrip in the case of structural inversion asymmetry, also affecting the steady domain wall motion induced by a spin-polarized current. This influence is here analytically studied in the framework of the extended Landau-Lifshitz-Gilbert equation, including the Rashba effect as an additive term of the effective field. Results of previous micromagnetic simulations and experiments have shown that this field yields an increased value of the Walker breakdown current together with an enlargement of the domain wall width. In order to analytically describe these results, the standard travelling wave ansatz for the steady domain wall motion is here adopted. Results of our investigations reveal the impossibility to reproduce, at the same time, the previous features and suggest the need of a more sophisticated model whose development requires, in turn, additional information to be extracted from ad hoc micromagnetic simulations.

  8. Stud arc welding in a magnetic field – Investigation of the influences on the arc motion

    International Nuclear Information System (INIS)

    Hartz-Behrend, K; Forster, G; Schein, J; Marqués, J L; Jenicek, A; Müller, M; Cramer, H; Jilg, A; Soyer, H

    2014-01-01

    Stud arc welding is widely used in the construction industry. For welding of studs with a diameter larger than 14 mm a ceramic ferrule is usually necessary in order to protect the weld pool. Disadvantages of using such a ferrule are that more metal is molten than necessary for a high quality welded joint and that the ferrule is a consumable generally thrown away after the welding operation. Investigations show that the ferrule can be omitted when the welding is carried out in a radially symmetric magnetic field within a shielding gas atmosphere. Due to the Lorentz force the arc is laterally shifted so that a very uniform and controlled melting of the stud contact surface as well as of the work piece can be achieved. In this paper a simplified physical model is presented describing how the parameters welding current, flux density of the magnetic field, radius of the arc and mass density of the shielding gas influence the velocity of the arc motion. The resulting equation is subsequently verified by comparing it to optical measurements of the arc motion. The proposed model can be used to optimize the required field distribution for the magnetic field stud welding process

  9. Motion of the MMS Spacecraft Relative to the Magnetic Reconnection Structure Observed on 16 October 2015 at 1307 UT

    Science.gov (United States)

    Denton, R. E.; Sonnerup, B. U. O.; Hasegawa, H.; Phan, T. D.; Russell, C. T.; Strangeway, R.; Giles, B. L.; Gershman, D.; Torbert, R. B.

    2016-01-01

    We analyze a magnetopause crossing by the Magnetospheric Multiscale (MMS) spacecraft at 1307 UT on 16 October 2016 that showed features of electron-scale reconnection. For this event, we find orthonormal LMN coordinates from the magnetic field, with N and L varying respectively along the maximum gradient and maximum variance directions. We find the motion along N from the Spatio-Temporal Difference analysis and motion along L from measured particle velocities. We locate the position of the magnetic X point, finding that MMS-4 passed within about 1A km from the X point and that MMS-3 and MMS-2 passed within about 1.7 km and 2.4 km, respectively, from the position of maximum out of plane current.

  10. Two-dimensional analysis of motion artifacts, including flow effects

    International Nuclear Information System (INIS)

    Litt, A.M.; Brody, A.S.; Spangler, R.A.; Scott, P.D.

    1990-01-01

    The effects of motion on magnetic resonance images have been theoretically analyzed for the case of a point-like object in simple harmonic motion and for other one-dimensional trajectories. The authors of this paper extend this analysis to a generalized two-dimensional magnetization with an arbitrary motion trajectory. The authors provide specific solutions for the clinically relevant cases of the cross-sections of cylindrical objects in the body, such as the aorta, which has a roughly one-dimensional, simple harmonic motion during respiration. By extending the solution to include inhomogeneous magnetizations, the authors present a model which allows the effects of motion artifacts and flow artifacts to be analyzed simultaneously

  11. Statistical Diagnosis Method of Conductor Motions in Superconducting Magnets to Predict their Quench Performance

    CERN Document Server

    Khomenko, B A; Rijllart, A; Sanfilippo, S; Siemko, A

    2001-01-01

    Premature training quenches are usually caused by the transient energy released within the magnet coil as it is energised. Two distinct varieties of disturbances exist. They are thought to be electrical and mechanical in origin. The first type of disturbance comes from non-uniform current distribution in superconducting cables whereas the second one usually originates from conductor motions or micro-fractures of insulating materials under the action of Lorentz forces. All of these mechanical events produce in general a rapid variation of the voltages in the so-called quench antennas and across the magnet coil, called spikes. A statistical method to treat the spatial localisation and the time occurrence of spikes will be presented. It allows identification of the mechanical weak points in the magnet without need to increase the current to provoke a quench. The prediction of the quench level from detailed analysis of the spike statistics can be expected.

  12. Motions of CMS detector structures due to the magnetic field forces as observed by the Link alignment system during the test of the 4 T magnet solenoid

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Moral, L.A.; Gomez, G.; Gonzalez-Sanchez, F.J.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Martinez, P.; Scodellaro, L.; Vila, I.; Virto, A.L. [Instituto de Fisica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander (Spain); Sobron, M. [Instituto de Fisica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander (Spain)], E-mail: sobron@ifca.unican.es; Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Molinero, A.; Navarrete, J.; Oller, J.C. [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain)] (and others)

    2009-07-21

    This document describes results obtained from the Link alignment system data recorded during the Compact Muon Solenoid (CMS) Magnet Test. A brief description of the system is followed by a discussion of the detected relative displacements (from micrometres to centimetres) between detector elements and rotations of detector structures (from microradians to milliradians). Observed displacements are studied as functions of the magnetic field intensity. In addition, the reconstructed positions of active element sensors are compared to their positions as measured by photogrammetry and the reconstructed motions due to the magnetic field strength are described.

  13. Motions of CMS Detector structures due to the magnetic field forces as observed by the Link Alignment System during the Test of the 4 Tesla Magnet Solenoid

    CERN Document Server

    Calderón, Alicia; González-Sánchez, F J; Martínez-Rivero, C; Matorras, Francisco; Rodrigo, Teresa; Martínez, P; Scodellaro, Luca; Sobrón, M; Vila, Ivan; Virto, A L; Alberdi, Javier; Arce, Pedro; Barcala, Jose Miguel; Calvo, Enrique; Ferrando, Antonio; Josa-Mutuberria, I; Molinero, Antonio; Navarrete, Jose Javier; Oller, Juan Carlos; Yuste, Ceferino

    2008-01-01

    This document describes results obtained from the Link Alignment System data recorded during the CMS Magnet Test. A brief description of the system is followed by the discussion of the detected relative displacements (from micrometres to centimetres) between detector elements and rotations of detector structures (from microradians to milliradians). Observed displacements are studied as functions of the magnetic field intensity. In addition, the reconstructed positions of active element sensors are compared to their positions as measured by photogrammetry and the reconstructed motions due to the magnetic field strength are described.

  14. Motions of CMS detector structures due to the magnetic field forces as observed by the Link alignment system during the test of the 4 T magnet solenoid

    International Nuclear Information System (INIS)

    Garcia-Moral, L.A.; Gomez, G.; Gonzalez-Sanchez, F.J.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Martinez, P.; Scodellaro, L.; Vila, I.; Virto, A.L.; Sobron, M.; Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Molinero, A.; Navarrete, J.; Oller, J.C.

    2009-01-01

    This document describes results obtained from the Link alignment system data recorded during the Compact Muon Solenoid (CMS) Magnet Test. A brief description of the system is followed by a discussion of the detected relative displacements (from micrometres to centimetres) between detector elements and rotations of detector structures (from microradians to milliradians). Observed displacements are studied as functions of the magnetic field intensity. In addition, the reconstructed positions of active element sensors are compared to their positions as measured by photogrammetry and the reconstructed motions due to the magnetic field strength are described.

  15. Motion of guiding center drift atoms in the electric and magnetic field of a Penning trap

    International Nuclear Information System (INIS)

    Kuzmin, S.G.; O'Neil, T.M.

    2005-01-01

    The ApparaTus for High precision Experiment on Neutral Antimatter and antihydrogen TRAP collaborations have produced antihydrogen atoms by recombination in a cryogenic antiproton-positron plasma. This paper discusses the motion of the weakly bound atoms in the electric and magnetic field of the plasma and trap. The effective electric field in the moving frame of the atom polarizes the atom, and then gradients in the field exert a force on the atom. An approximate equation of motion for the atom center of mass is obtained by averaging over the rapid internal dynamics of the atom. The only remnant of the atom internal dynamics that enters this equation is the polarizability for the atom. This coefficient is evaluated for the weakly bound and strongly magnetized (guiding center drift) atoms understood to be produced in the antihydrogen experiments. Application of the approximate equation of motion shows that the atoms can be trapped radially in the large space charge field near the edge of the positron column. Also, an example is presented for which there is full three-dimensional trapping, not just radial trapping. Even untrapped atoms follow curved trajectories, and such trajectories are discussed for the important class of atoms that reach a field ionization diagnostic. Finally, the critical field for ionization is determined as an upper bound on the range of applicability of the theory

  16. The classical equations of motion for a spinning point particle with charge and magnetic moment

    International Nuclear Information System (INIS)

    Rowe, E.G.P.; Rowe, G.T.

    1987-01-01

    The classical, special relativistic equations of motion are derived for a spinning point particle interacting with the electromagnetic field through its charge and magnetic moment. Radiation reaction is included. The energy tensors for the particle and for the field are developed as well-defined distributions; consequently no infinities appear. The magnitude of spin and the rest mass are conserved. (orig.)

  17. Estafette of drift resonances, stochasticity and control of particle motion in a toroidal magnetic trap

    International Nuclear Information System (INIS)

    Shishkin, Alexander A.

    2001-02-01

    A new method of particle motion control in toroidal magnetic traps with rotational transform using the estafette of drift resonances and stochasticity of particle trajectories is proposed. The use of the word estafette' here means that the particle passes through a set of resonances in consecutive order from one to another during its motion. The overlapping of adjacent resonances can be moved radially from the center to the edge of the plasma by switching on the corresponding perturbations in accordance with a particular rule in time. In this way particles (e.g. cold alpha-particle) can be removed from the center of the confinement volume to the plasma periphery. For the analytical treatment of the stochastic behaviour of particle motion the stochastic diffusion coefficients D r, r, D r,θ , D θ,θ are introduced. The new approach is demonstrated by numerical computations of the test helium particle trajectories in the toroidal trap Large Helical Device. (author)

  18. Modulated Magnetic Nanowires for Controlling Domain Wall Motion: Toward 3D Magnetic Memories

    KAUST Repository

    Ivanov, Yurii P.; Chuvilin, Andrey; Lopatin, Sergei; Kosel, Jü rgen

    2016-01-01

    Cylindrical magnetic nanowires are attractive materials for next generation data storage devices owing to the theoretically achievable high domain wall velocity and their efficient fabrication in highly dense arrays. In order to obtain control over domain wall motion, reliable and well-defined pinning sites are required. Here, we show that modulated nanowires consisting of alternating nickel and cobalt sections facilitate efficient domain wall pinning at the interfaces of those sections. By combining electron holography with micromagnetic simulations, the pinning effect can be explained by the interaction of the stray fields generated at the interface and the domain wall. Utilizing a modified differential phase contrast imaging, we visualized the pinned domain wall with a high resolution, revealing its three-dimensional vortex structure with the previously predicted Bloch point at its center. These findings suggest the potential of modulated nanowires for the development of high-density, three-dimensional data storage devices. © 2016 American Chemical Society.

  19. Modulated Magnetic Nanowires for Controlling Domain Wall Motion: Toward 3D Magnetic Memories

    KAUST Repository

    Ivanov, Yurii P.

    2016-05-03

    Cylindrical magnetic nanowires are attractive materials for next generation data storage devices owing to the theoretically achievable high domain wall velocity and their efficient fabrication in highly dense arrays. In order to obtain control over domain wall motion, reliable and well-defined pinning sites are required. Here, we show that modulated nanowires consisting of alternating nickel and cobalt sections facilitate efficient domain wall pinning at the interfaces of those sections. By combining electron holography with micromagnetic simulations, the pinning effect can be explained by the interaction of the stray fields generated at the interface and the domain wall. Utilizing a modified differential phase contrast imaging, we visualized the pinned domain wall with a high resolution, revealing its three-dimensional vortex structure with the previously predicted Bloch point at its center. These findings suggest the potential of modulated nanowires for the development of high-density, three-dimensional data storage devices. © 2016 American Chemical Society.

  20. The dust motion inside the magnetized sheath - The effect of drag forces

    International Nuclear Information System (INIS)

    Pandey, B. P.; Samarian, A.; Vladimirov, S. V.

    2010-01-01

    The isolated charged dust inside the magnetized plasma sheath moves under the influence of the electron and ion drag force and the sheath electrostatic field. The charge on the dust is a function of its radius as well as the value of the ambient sheath potential. It is shown that the charge on the dust determines its trajectory and dust performs the spiraling motion inside the sheath. The location of the turning spiral is determined by the number of negative charge on the dust, which in turn is a function of the dust radius. The back and forth spiraling motion finally causes the dust to move in a small, narrow region of the sheath. For a bigger dust particle, the dust moves closer to the sheath presheath boundary suggesting that the bigger grains, owing to the strong repulsion between the wall and dust, will be unable to travel inside the sheath. Only small, micron-sized grains can travel closer to the wall before repulsion pushes it back toward the plasma-sheath boundary. The temporal behavior of the spiraling dust motion appears like a damped harmonic oscillation, suggesting that the plasma drag force causes dissipation of the electrostatic energy. However, after initial damping, the grain keeps oscillating although with much smaller amplitude. The possible application of the present results to the ongoing sheath experiments is discussed.

  1. Magnetic conditioning in superfluid

    International Nuclear Information System (INIS)

    Caspi, S.

    1988-08-01

    Improvements in superconducting magnet technology have reduced to a handful the number of training quenches typical of dipole magnets. The number of training quenches in long (17 m) and short (1--2 m) SSC magnets are now about the same (operating at 6.6 tesla and 4.4 K). Yet the steps necessary to totally eliminate training are in the future RandD plans for magnet construction and conductor motion prevention. The accepted hypothesis is that Lorentz forces and poor mechanical properties of superconducting cables are the cause of conductor motion. Conductor motion reduces the stored energy in the cable by converting it into heat. The small amount of heat generated (millijoules) during motion is usually enough to quench the magnet when it is close to short sample. During training, the magnet performance normally improves with the number of quenches. It is not the quench itself that improves magnet performance but rather the fact that once conductor motion has occurred it will probably not repeat itself unless subjected to higher forces. Conditioning is a process that enables the magnet to reduce its stored energy without causing a premature quench. During the conditioning process the magnet is further cooled from its operating temperature of 4.4 K to 1.8 K by converting He I into He II. As a result the magnet is placed in a state where it has excess stability as well as excellent heat transfer capabilities. Although this does not eliminate motion, if the magnet is now cycled to /approximately/10% above its operating field at 4.4 K (which is above short sample) the excess stability should be enough to prevent quenching and reduce the probability of conductor motion and training once the magnet has been warmed back up to its operating temperature of 4.4 K. 3 refs., 5 figs

  2. Magnetic conditioning in superfluid

    Energy Technology Data Exchange (ETDEWEB)

    Caspi, S.

    1988-08-01

    Improvements in superconducting magnet technology have reduced to a handful the number of training quenches typical of dipole magnets. The number of training quenches in long (17 m) and short (1--2 m) SSC magnets are now about the same (operating at 6.6 tesla and 4.4 K). Yet the steps necessary to totally eliminate training are in the future RandD plans for magnet construction and conductor motion prevention. The accepted hypothesis is that Lorentz forces and poor mechanical properties of superconducting cables are the cause of conductor motion. Conductor motion reduces the stored energy in the cable by converting it into heat. The small amount of heat generated (millijoules) during motion is usually enough to quench the magnet when it is close to short sample. During training, the magnet performance normally improves with the number of quenches. It is not the quench itself that improves magnet performance but rather the fact that once conductor motion has occurred it will probably not repeat itself unless subjected to higher forces. Conditioning is a process that enables the magnet to reduce its stored energy without causing a premature quench. During the conditioning process the magnet is further cooled from its operating temperature of 4.4 K to 1.8 K by converting He I into He II. As a result the magnet is placed in a state where it has excess stability as well as excellent heat transfer capabilities. Although this does not eliminate motion, if the magnet is now cycled to /approximately/10% above its operating field at 4.4 K (which is above short sample) the excess stability should be enough to prevent quenching and reduce the probability of conductor motion and training once the magnet has been warmed back up to its operating temperature of 4.4 K. 3 refs., 5 figs.

  3. Dynamic motion analysis of fetuses with central nervous system disorders by cine magnetic resonance imaging using fast imaging employing steady-state acquisition and parallel imaging: a preliminary result.

    Science.gov (United States)

    Guo, Wan-Yuo; Ono, Shigeki; Oi, Shizuo; Shen, Shu-Huei; Wong, Tai-Tong; Chung, Hsiao-Wen; Hung, Jeng-Hsiu

    2006-08-01

    The authors present a novel cine magnetic resonance (MR) imaging, two-dimensional (2D) fast imaging employing steady-state acquisition (FIESTA) technique with parallel imaging. It achieves temporal resolution at less than half a second as well as high spatial resolution cine imaging free of motion artifacts for evaluating the dynamic motion of fetuses in utero. The information obtained is used to predict postnatal outcome. Twenty-five fetuses with anomalies were studied. Ultrasonography demonstrated severe abnormalities in five of the fetuses; the other 20 fetuses constituted a control group. The cine fetal MR imaging demonstrated fetal head, neck, trunk, extremity, and finger as well as swallowing motions. Imaging findings were evaluated and compared in fetuses with major central nervous system (CNS) anomalies in five cases and minor CNS, non-CNS, or no anomalies in 20 cases. Normal motility was observed in the latter group. For fetuses in the former group, those with abnormal motility failed to survive after delivery, whereas those with normal motility survived with functioning preserved. The power deposition of radiofrequency, presented as specific absorption rate (SAR), was calculated. The SAR of FIESTA was approximately 13 times lower than that of conventional MR imaging of fetuses obtained using single-shot fast spin echo sequences. The following conclusions are drawn: 1) Fetal motion is no longer a limitation for prenatal imaging after the implementation of parallel imaging with 2D FIESTA, 2) Cine MR imaging illustrates fetal motion in utero with high clinical reliability, 3) For cases involving major CNS anomalies, cine MR imaging provides information on extremity motility in fetuses and serves as a prognostic indicator of postnatal outcome, and 4) The cine MR used to observe fetal activity is technically 2D and conceptually three-dimensional. It provides four-dimensional information for making proper and timely obstetrical and/or postnatal management

  4. Exoskeleton Motion Control for Children Walking Rehabilitation

    Directory of Open Access Journals (Sweden)

    Cristina Ploscaru

    2016-06-01

    Full Text Available This paper introduces a quick method for motion control of an exoskeleton used on children walking rehabilitation with ages between four to seven years old. The exoskeleton used on this purpose has six servomotors which work independently and actuates each human lower limb joints (hips, knees and ankles. For obtaining the desired motion laws, a high-speed motion analysis equipment was used. The experimental rough data were mathematically modeled in order to obtain the proper motion equations for controlling the exoskeleton servomotors.

  5. Motional Stark Effect measurements of the local magnetic field in high temperature fusion plasmas

    Science.gov (United States)

    Wolf, R. C.; Bock, A.; Ford, O. P.; Reimer, R.; Burckhart, A.; Dinklage, A.; Hobirk, J.; Howard, J.; Reich, M.; Stober, J.

    2015-10-01

    The utilization of the Motional Stark Effect (MSE) experienced by the neutral hydrogen or deuterium injected into magnetically confined high temperature plasmas is a well established technique to infer the internal magnetic field distribution of fusion experiments. In their rest frame, the neutral atoms experience a Lorentz electric field, EL = v × B, which results in a characteristic line splitting and polarized line emission. The different properties of the Stark multiplet allow inferring, both the magnetic field strength and the orientation of the magnetic field vector. Besides recording the full MSE spectrum, several types of polarimeters have been developed to measure the polarization direction of the Stark line emission. To test physics models of the magnetic field distribution and dynamics, the accuracy requirements are quite demanding. In view of these requirements, the capabilities and issues of the different techniques are discussed, including the influence of the Zeeman Effect and the sensitivity to radial electric fields. A newly developed Imaging MSE system, which has been tested on the ASDEX Upgrade tokamak, is presented. The sensitivity allows to resolve sawtooth oscillations. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

  6. Prostate gland motion assessed with cine-magnetic resonance imaging (cine-MRI)

    International Nuclear Information System (INIS)

    Ghilezan, Michel J.; Jaffray, David A.; Siewerdsen, Jeffrey H.; Herk, Marcel van; Shetty, Anil; Sharpe, Michael B.; Zafar Jafri, Syed; Vicini, Frank A.; Matter, Richard C.; Brabbins, Donald S.; Martinez, Alvaro A.

    2005-01-01

    Purpose: To quantify prostate motion during a radiation therapy treatment using cine-magnetic resonance imaging (cine-MRI) for time frames comparable to that expected in an image-guided radiation therapy treatment session (20-30 min). Materials and Methods: Six patients undergoing radiation therapy for prostate cancer were imaged on 3 days, over the course of therapy (Weeks 1, 3, and 5). Four hundred images were acquired during the 1-h MRI session in 3 sagittal planes through the prostate at 6-s intervals. Eleven anatomic points of interest (POIs) have been used to characterize prostate/bony pelvis/abdominal wall displacement. Motion traces and standard deviation for each of the 11 POIs have been determined. The probability of displacement over time has also been calculated. Results: Patients were divided into 2 groups according to rectal filling status: full vs. empty rectum. The displacement of POIs (standard deviation) ranged from 0.98 to 1.72 mm for the full-rectum group and from 0.68 to 1.04 mm for the empty-rectum group. The low standard deviations in position (2 mm or less) would suggest that these excursions have a low frequency of occurrence. The most sensitive prostate POI to rectal wall motion was the midposterior with a standard deviation of 1.72 mm in the full-rectum group vs. 0.79 mm in the empty-rectum group (p 0.0001). This POI has a 10% probability of moving more than 3 mm in a time frame of ∼1 min if the rectum is full vs. ∼20 min if the rectum is empty. Conclusion: Motion of the prostate and seminal vesicles during a time frame similar to a standard treatment session is reduced compared to that reported in interfraction studies. The most significant predictor for intrafraction prostate motion is the status of rectal filling. A prostate displacement of <3 mm (90%) can be expected for the 20 min after the moment of initial imaging for patients with an empty rectum. This is not the case for patients presenting with full rectum. The determination

  7. Terahertz Generation & Vortex Motion Control in Superconductors

    Science.gov (United States)

    Nori, Franco

    2005-03-01

    A grand challenge is to controllably generate electromagnetic waves in layered superconducting compounds because of its Terahertz frequency range. We propose [1] four experimentally realizable devices for generating continuous and pulsed THz radiation in a controllable frequency range. We also describe [2-4] several novel devices for controlling the motion of vortices in superconductors, including a reversible rectifier made of a magnetic-superconducting hybrid structure [4]. Finally, we summarize a study [5] of the friction force felt by moving vortices. 1) S. Savel'ev, V. Yampol'skii, A. Rakhmanov, F. Nori, Tunable Terahertz radiation from Josephson vortices, preprint 2) S. Savel'ev and F. Nori, Experimentally realizable devices for controlling the motion of magnetic flux quanta, Nature Mat. 1, 179 (2002) 3) S. Savel'ev, F. Marchesoni, F. Nori, Manipulating small particles, PRL 92, 160602 (2004); B. Zhu, F. Marchesoni, F. Nori, Controlling the motion of magnetic flux quanta, PRL 92, 180602 (2004) 4) J.E. Villegas, et al., Reversible Rectifier that Controls the Motion of Magnetic Flux Quanta, Science 302, 1188 (2003) 5) A. Maeda, et al., Nano-scale friction: kinetic friction of magnetic flux quanta and charge density waves, preprint

  8. 'Magnetic Resonance Motion Imaging' for functional diagnosis of the musculo-skeletal system

    International Nuclear Information System (INIS)

    Friedrich, K.M.

    2002-06-01

    Purpose: radiological studies of joint and spine function are an important part of the diagnosis and therapy management for musculo-skeletal diseases affecting range-of-motion. The objective of this study was to investigate the integration and developement of the clinical application of currently available MR-tomographic techniques, which can be summarized as 'Magnetic Resonance Motion Imaging (MRMI)'. Material and methods: five healthy volunteers (three women and two men; mean age 21.8?4.4) and ten patients (eight women and two men; mean age 31.4?12.6) took part in the study. A total of 21 examinations with real-time motion-MRI were performed on selected peripheric joints (seven patellofemoral joints, six femorotibial joints, one cervical spine, two wrists, three ankles and two temporomandibular joints) with a 1.0T unit (Philips Intera T10) using T1-weighted gradient-echo and opposed-phase imaging sequences. For the examination of the patellofemoral joint, the femorotibial joint, the wrist and the tmj a dedicated positioning-device was used. Results were correlated with static MR-Images. Results: the quickly parcticable sequence of the examinations was not straining for the patients. The quality of imaging was only insignificantly lower as compared with static gradient-echo sequences. No artifacts were seen which could influence the evaluation. The visualisation of motions was very good. The quantification of the maximum extent of dysfunctions could be judged better with a higher sensitivity in real-time-mode than in static images. Conclusion: from the results of this study a three-step-plan for the radiodiagnostic procedure in cases of functional disorders of selected joints and the spine can be deduced, which uses static MR-imaging as first step. In case of unsolved questions MRMI is done (step 2). To obtain measurements, static MR-Images at different points of the motion range(kinematic MR-Imaging) should be done (step 3). This plan of 'motion-MRI' is well

  9. SPATIAL MOTION OF THE MAGELLANIC CLOUDS: TIDAL MODELS RULED OUT?

    International Nuclear Information System (INIS)

    Ruzicka, Adam; Palous, Jan; Theis, Christian

    2009-01-01

    Recently, Kallivayalil et al. derived new values of the proper motion for the Large and Small Magellanic Clouds (LMC and SMC, respectively). The spatial velocities of both Clouds are unexpectedly higher than their previous values resulting from agreement between the available theoretical models of the Magellanic System and the observations of neutral hydrogen (H I) associated with the LMC and the SMC. Such proper motion estimates are likely to be at odds with the scenarios for creation of the large-scale structures in the Magellanic System suggested so far. We investigated this hypothesis for the pure tidal models, as they were the first ones devised to explain the evolution of the Magellanic System, and the tidal stripping is intrinsically involved in every model assuming the gravitational interaction. The parameter space for the Milky Way (MW)-LMC-SMC interaction was analyzed by a robust search algorithm (genetic algorithm) combined with a fast, restricted N-body model of the interaction. Our method extended the known variety of evolutionary scenarios satisfying the observed kinematics and morphology of the Magellanic large-scale structures. Nevertheless, assuming the tidal interaction, no satisfactory reproduction of the H I data available for the Magellanic Clouds was achieved with the new proper motions. We conclude that for the proper motion data by Kallivayalil et al., within their 1σ errors, the dynamical evolution of the Magellanic System with the currently accepted total mass of the MW cannot be explained in the framework of pure tidal models. The optimal value for the western component of the LMC proper motion was found to be μ W lmc ∼> -1.3 mas yr -1 in case of tidal models. It corresponds to the reduction of the Kallivayalil et al. value for μ W lmc by ∼ 40% in its magnitude.

  10. Fokker-Planck equation for the non-Markovian Brownian motion in the presence of a magnetic field

    Science.gov (United States)

    Das, Joydip; Mondal, Shrabani; Bag, Bidhan Chandra

    2017-10-01

    In the present study, we have proposed the Fokker-Planck equation in a simple way for a Langevin equation of motion having ordinary derivative (OD), the Gaussian random force and a generalized frictional memory kernel. The equation may be associated with or without conservative force field from harmonic potential. We extend this method for a charged Brownian particle in the presence of a magnetic field. Thus, the present method is applicable for a Langevin equation of motion with OD, the Gaussian colored thermal noise and any kind of linear force field that may be conservative or not. It is also simple to apply this method for the colored Gaussian noise that is not related to the damping strength.

  11. Prognostic value of high-dose dobutamine stress magnetic resonance imaging in 1,493 consecutive patients: assessment of myocardial wall motion and perfusion.

    Science.gov (United States)

    Korosoglou, Grigorios; Elhmidi, Yacine; Steen, Henning; Schellberg, Dieter; Riedle, Nina; Ahrens, Johannes; Lehrke, Stephanie; Merten, Constanze; Lossnitzer, Dirk; Radeleff, Jannis; Zugck, Christian; Giannitsis, Evangelos; Katus, Hugo A

    2010-10-05

    This study sought to determine the prognostic value of wall motion and perfusion assessment during high-dose dobutamine stress (DS) cardiac magnetic resonance imaging (MRI) in a large patient cohort. DS-MRI offers the possibility to integrate myocardial perfusion and wall motion analysis in a single examination for the detection of coronary artery disease (CAD). A total of 1,493 consecutive patients with suspected or known CAD underwent DS-MRI, using a standard protocol in a 1.5-T magnetic resonance scanner. Wall motion and perfusion were assessed at baseline and during stress, and outcome data including cardiac death, nonfatal myocardial infarction ("hard events"), and "late" revascularization performed >90 days after the MR scans were collected during a 2 ± 1 year follow-up period. Fifty-three hard events, including 14 cardiac deaths and 39 nonfatal infarctions, occurred during the follow-up period, whereas 85 patients underwent "late" revascularization. Using multivariable regression analysis, an abnormal result for wall motion or perfusion during stress yielded the strongest independent prognostic value for both hard events and late revascularization, clearly surpassing that of clinical and baseline magnetic resonance parameters (for wall motion: adjusted hazard ratio [HR] of 5.9 [95% confidence interval (CI): 2.5 to 13.6] for hard events and of 3.1 [95% CI: 1.7 to 5.6] for late revascularization, and for perfusion: adjusted HR of 5.4 [95% CI: 2.3 to 12.9] for hard events and of 6.2 [95% CI: 3.3 to 11.3] for late revascularization, p < 0.001 for all). DS-MRI can accurately identify patients who are at increased risk for cardiac death and myocardial infarction, separating them from those with normal findings, who have very low risk for future cardiac events. (Prognostic Value of High Dose Dobutamine Stress Magnetic Resonance Imaging; NCT00837005). Copyright © 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  12. A Pan-STARRS1 Proper-Motion Survey for Young Brown Dwarfs in the Nearest Star-Forming Regions and a Reddening-Free Classification Method for Ultracool Dwarfs

    Science.gov (United States)

    Zhang, Zhoujian; Liu, Michael C.; Best, William M. J.; Magnier, Eugene; Aller, Kimberly

    2018-01-01

    Young brown dwarfs are of prime importance to investigate the universality of the initial mass function (IMF). Based on photometry and proper motions from the Pan-STARRS1 (PS1) 3π survey, we are conducting the widest and deepest brown dwarf survey in the nearby star-forming regions, Taurus–Auriga (Taurus) and Upper Scorpius (USco). Our work is the first to measure proper motions, a robust proxy of membership, for brown dwarf candidates in Taurus and USco over such a large area and long time baseline (≈ 15 year) with such high precision (≈ 4 mas yr-1). Since extinction complicates spectral classification, we have developed a new approach to quantitatively determine reddening-free spectral types, extinctions, and gravity classifications for mid-M to late-L ultracool dwarfs (≈ 100–5 MJup), using low-resolution near-infrared spectra. So far, our IRTF/SpeX spectroscopic follow-up has increased the substellar and planetary-mass census of Taurus by ≈ 50% and almost doubled the substellar census of USco, constituting the largest single increases of brown dwarfs and free-floating planets found in both regions to date. Most notably, our new discoveries reveal an older (> 10 Myr) low-mass population in Taurus, in accord with recent studies of the higher-mass stellar members. In addition, the mass function appears to differ between the younger and older Taurus populations, possibly due to incompleteness of the older stellar members or different star formation processes. Upon completion, our survey will establish the most complete substellar and planetary-mass census in both Taurus and USco associations, make a significant addition to the low-mass IMF in both regions, and deliver more comprehensive pictures of star formation histories.

  13. Modeling the angular motion dynamics of spacecraft with a magnetic attitude control system based on experimental studies and dynamic similarity

    Science.gov (United States)

    Kulkov, V. M.; Medvedskii, A. L.; Terentyev, V. V.; Firsyuk, S. O.; Shemyakov, A. O.

    2017-12-01

    The problem of spacecraft attitude control using electromagnetic systems interacting with the Earth's magnetic field is considered. A set of dimensionless parameters has been formed to investigate the spacecraft orientation regimes based on dynamically similar models. The results of experimental studies of small spacecraft with a magnetic attitude control system can be extrapolated to the in-orbit spacecraft motion control regimes by using the methods of the dimensional and similarity theory.

  14. Characterization of the Praesepe star cluster by photometry and proper motions with 2MASS, PPMXL, and Pan-STARRS

    Energy Technology Data Exchange (ETDEWEB)

    Wang, P. F.; Chen, W. P. [Department of Physics, National Central University, 300 Jhongda Road, Jhongli 32001, Taiwan (China); Lin, C. C.; Huang, C. K.; Panwar, N.; Lee, C. H. [Graduate Institute of Astronomy, National Central University, 300 Jhongda Road, Jhongli 32001, Taiwan (China); Pandey, A. K. [Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263129 (India); Tsai, M. F.; Tang, C.-H. [Department of Computer Science and Information Engineering, National Central University, 300 Jhongda Road, Jhongli 32001, Taiwan (China); Goldman, B. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Burgett, W. S.; Chambers, K. C.; Flewelling, H.; Heasley, J. N.; Hodapp, K. W.; Huber, M. E.; Jedicke, R.; Kaiser, N. [Institute for Astronomy, University of Hawai' i, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Draper, P. W. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Grav, T. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); and others

    2014-03-20

    Membership identification is the first step in determining the properties of a star cluster. Low-mass members in particular could be used to trace the dynamical history, such as mass segregation, stellar evaporation, or tidal stripping, of a star cluster in its Galactic environment. We identified member candidates of the intermediate-age Praesepe cluster (M44) with stellar masses ∼0.11-2.4 M {sub ☉}, using Panoramic Survey Telescope And Rapid Response System and Two Micron All Sky Survey photometry, and PPMXL proper motions. Within a sky area of 3° radius, 1040 candidates are identified, of which 96 are new inclusions. Using the same set of selection criteria on field stars, an estimated false positive rate of 16% was determined, suggesting that 872 of the candidates are true members. This most complete and reliable membership list allows us to favor the BT-Settl model over other stellar models. The cluster shows a distinct binary track above the main sequence, with a binary frequency of 20%-40%, and a high occurrence rate of similar mass pairs. The mass function is consistent with that of the disk population but shows a deficit of members below 0.3 solar masses. A clear mass segregation is evidenced, with the lowest-mass members in our sample being evaporated from this disintegrating cluster.

  15. An Integrated Approach to Motion and Sound

    National Research Council Canada - National Science Library

    Hahn, James K; Geigel, Joe; Lee, Jong W; Gritz, Larry; Takala, Tapio; Mishra, Suneil

    1995-01-01

    Until recently, sound has been given little attention in computer graphics and related domains of computer animation and virtual environments, although sounds which are properly synchronized to motion...

  16. Controlling magnetic domain wall motion in the creep regime in He+-irradiated CoFeB/MgO films with perpendicular anisotropy

    International Nuclear Information System (INIS)

    Herrera Diez, L.; García-Sánchez, F.; Adam, J.-P.; Devolder, T.; Eimer, S.; El Hadri, M. S.; Ravelosona, D.; Lamperti, A.; Mantovan, R.; Ocker, B.

    2015-01-01

    This study presents the effective tuning of perpendicular magnetic anisotropy in CoFeB/MgO thin films by He + ion irradiation and its effect on domain wall motion in a low field regime. Magnetic anisotropy and saturation magnetisation are found to decrease as a function of the irradiation dose which can be related to the observed irradiation-induced changes in stoichiometry at the CoFeB/MgO interface. These changes in the magnetic intrinsic properties of the film are reflected in the domain wall dynamics at low magnetic fields (H) where irradiation is found to induce a significant decrease in domain wall velocity (v). For all irradiation doses, domain wall velocities at low fields are well described by a creep law, where Ln(v) vs. H −1∕4 behaves linearly, up to a maximum field H*, which has been considered as an approximation to the value of the depinning field H dep . In turn, H* ≈ H dep is seen to increase as a function of the irradiation dose, indicating an irradiation-induced extension of the creep regime of domain wall motion

  17. Symplectic tracking using point magnets in the presence of a longitudinal magnetic field

    International Nuclear Information System (INIS)

    Parzen, G.

    1993-09-01

    In the absence of a longitudinal magnetic field, symplectic tracking can be achieved by replacing the magnets by a series of point magnets and drift spaces. To treat the case when a longitudinal magnetic field is also present, this procedure is modified in this paper by replacing the drift space by a solenoidal drift, which is defined as the motion of a particle in a uniform longitudinal magnetic field. A symplectic integrator can be obtained by subdividing each magnet into pieces and replacing each magnet piece by point magnets, with only transverse fields, and solenoidal drift spaces. The reference orbit used here is made up of arcs of circles and straight lines which join smoothly with each other. For this choice of reference orbit, the required results are obtained to track particles, which are the transfer functions, and the transfer time for the different elements. It is shown that these results provide a symplectic integrator, and they are exact in the sense that as the number of magnet pieces is increased, the particle motion will converge to the particle motion of the exact equations of motion

  18. Cinematic study of temporomandibular joint motion using ultra-fast magnetic resonance imaging.

    Science.gov (United States)

    Manière-Ezvan, A; Havet, T; Franconi, J M; Quémar, J C; de Certaines, J D

    1999-10-01

    Magnetic Resonance Images (MRI) of the temporomandibular joint (TMJ) are usually performed to study the opening/closing movements of the mandible and have up to now been pseudodynamic step-by-step images simulating condylar motion by post-processing reconstruction. The aim of this study was: 1. to optimize a TMJ cine-imaging method to give a better clinical result than the step-by-step methods; 2. to develop an ultra-fast MRI Gradient Echo (GE) sequence for this purpose; and 3. to analyze condylar movements in the sagittal, coronal and para-axial planes during border mandibular displacements and chewing. Both TM joints were studied in six asymptomatic volunteers. The method involved a compromise between in-plane resolution, slice thickness, signal-to-noise ratio and time resolution. Routine clinical use was found to be a GE pulse sequence providing three images per second with an isometric voxel resolution of approximately two millimeters in ridge. This did not allow visualization of the disk. Using this sequence enabled real and simultaneous condylar displacement observation in the three planes of space and therefore contributed to a better functional diagnosis of pathologic TMJ motions.

  19. Early Improper Motion Detection in Golf Swings Using Wearable Motion Sensors: The First Approach

    Science.gov (United States)

    Stančin, Sara; Tomažič, Sašo

    2013-01-01

    This paper presents an analysis of a golf swing to detect improper motion in the early phase of the swing. Led by the desire to achieve a consistent shot outcome, a particular golfer would (in multiple trials) prefer to perform completely identical golf swings. In reality, some deviations from the desired motion are always present due to the comprehensive nature of the swing motion. Swing motion deviations that are not detrimental to performance are acceptable. This analysis is conducted using a golfer's leading arm kinematic data, which are obtained from a golfer wearing a motion sensor that is comprised of gyroscopes and accelerometers. Applying the principal component analysis (PCA) to the reference observations of properly performed swings, the PCA components of acceptable swing motion deviations are established. Using these components, the motion deviations in the observations of other swings are examined. Any unacceptable deviations that are detected indicate an improper swing motion. Arbitrarily long observations of an individual player's swing sequences can be included in the analysis. The results obtained for the considered example show an improper swing motion in early phase of the swing, i.e., the first part of the backswing. An early detection method for improper swing motions that is conducted on an individual basis provides assistance for performance improvement. PMID:23752563

  20. Fetal cardiac cine imaging using highly accelerated dynamic MRI with retrospective motion correction and outlier rejection.

    Science.gov (United States)

    van Amerom, Joshua F P; Lloyd, David F A; Price, Anthony N; Kuklisova Murgasova, Maria; Aljabar, Paul; Malik, Shaihan J; Lohezic, Maelene; Rutherford, Mary A; Pushparajah, Kuberan; Razavi, Reza; Hajnal, Joseph V

    2018-01-01

    Development of a MRI acquisition and reconstruction strategy to depict fetal cardiac anatomy in the presence of maternal and fetal motion. The proposed strategy involves i) acquisition and reconstruction of highly accelerated dynamic MRI, followed by image-based ii) cardiac synchronization, iii) motion correction, iv) outlier rejection, and finally v) cardiac cine reconstruction. Postprocessing entirely was automated, aside from a user-defined region of interest delineating the fetal heart. The method was evaluated in 30 mid- to late gestational age singleton pregnancies scanned without maternal breath-hold. The combination of complementary acquisition/reconstruction and correction/rejection steps in the pipeline served to improve the quality of the reconstructed 2D cine images, resulting in increased visibility of small, dynamic anatomical features. Artifact-free cine images successfully were produced in 36 of 39 acquired data sets; prolonged general fetal movements precluded processing of the remaining three data sets. The proposed method shows promise as a motion-tolerant framework to enable further detail in MRI studies of the fetal heart and great vessels. Processing data in image-space allowed for spatial and temporal operations to be applied to the fetal heart in isolation, separate from extraneous changes elsewhere in the field of view. Magn Reson Med 79:327-338, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

  1. Motion behaviour of magneto-sensitive elastomers controlled by an external magnetic field for sensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Volkova, T.I., E-mail: tatiana.volkova@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany); Böhm, V., E-mail: valter.boehm@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany); Kaufhold, T., E-mail: tobias.kaufhold@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany); Popp, J., E-mail: jana.popp@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany); Becker, F., E-mail: felix.becker@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany); Borin, D.Yu., E-mail: dmitry.borin@tu-dresden.de [Technische Universität Dresden, Magnetofluiddynamics, Measuring and Automation Technology, D-01062 Dresden (Germany); Stepanov, G.V., E-mail: gstepanov@mail.ru [State Institute of Chemistry and Technology of Organoelement Compounds, 105118 Moscow (Russian Federation); Zimmermann, K., E-mail: klaus.zimmermann@tu-ilmenau.de [Technische Universität Ilmenau, Faculty of Mechanical Engineering, Technical Mechanics Group, D-98693 Ilmenau (Germany)

    2017-06-01

    The development of sensor systems with a complex adaptive regulation of the operating sensitivity and behaviour is an actual scientific and technical challenge. Smart materials like magneto-sensitive elastomers (MSE) are seen as one potential solution for this problem, since their mechanical properties may be controlled by external magnetic fields. The present paper deals with the investigation of elastic and damping properties of MSE containing magnetically soft particles under the influence of a uniform magnetic field. Based on the measurement of the first eigenfrequency of free bending vibrations of a fixed beam, the effective Young's modulus is evaluated theoretically and also numerically using Finite Element Method. It is shown that this parameter, as well as the first eigenfrequency of the beam, increases monotonically with the magnitude of the applied magnetic field. The results are aimed to develop an acceleration sensor with adaptive magnetically controllable sensitivity range for the detection of external mechanical stimuli of the environment. - Highlights: • The motion behaviour of magneto-sensitive elastomers (MSE) with magnetically soft particles is investigated. • The first eigenfrequency of free bending vibrations of an MSE beam can be controlled by a uniform magnetic field. • Based on the experimental results, the effective Young's modulus of the system is evaluated theoretically and numerically. • The Young's modulus increases monotonically with the magnitude of the applied magnetic field. • The controlled mechanical compliance of MSE may be used for development of sensor systems with adaptive sensitivity range.

  2. Coupled transverse motion

    International Nuclear Information System (INIS)

    Teng, L.C.

    1989-01-01

    The magnetic field in an accelerator or a storage ring is usually so designed that the horizontal (x) and the vertical (y) motions of an ion are uncoupled. However, because of imperfections in construction and alignment, some small coupling is unavoidable. In this lecture, we discuss in a general way what is known about the behaviors of coupled motions in two degrees-of-freedom. 11 refs., 6 figs

  3. In-vivo quantification of wall motion in cerebral aneurysms from 2D cine phase contrast magnetic resonance images

    Energy Technology Data Exchange (ETDEWEB)

    Karmonik, C. [The Methodist Hospital Research Inst., Houston (United States); Diaz, O.; Klucznik, R. [The Methodist Hospital, Houston (United States); Grossman, R. [The Methodist Hospital, Houston (United States). Neurosurgery

    2010-02-15

    Purpose: The quantification of wall motion in cerebral aneurysms is of interest for the assessment of aneurysmal rupture risk, for providing boundary conditions for computational simulations and as a validation tool for theoretical models. Materials and Methods: 2D cine phase contrast magnetic resonance imaging (2D pcMRI) in combination with quantitative magnetic resonance angiography (QMRA) was evaluated for measuring wall motion in 7 intracranial aneurysms. In each aneurysm, 2 (in one case 3) cross sections, oriented approximately perpendicular to each other, were measured. Results: The maximum aneurysmal wall distention ranged from 0.16 mm to 1.6 mm (mean 0.67 mm), the maximum aneurysmal wall contraction was -1.91 mm to -0.34 mm (mean 0.94 mm), and the average wall displacement ranged from 0.04 mm to 0.31 mm (mean 0.15 mm). Statistically significant correlations between average wall displacement and the shape of inflow curves (p-value < 0.05) were found in 7 of 15 cross sections; statistically significant correlations between the displacement of the luminal boundary center point and the shape of inflow curves (p-value < 0.05) were found in 6 of 15 cross sections. Conclusion: 2D pcMRI in combination with QMRA is capable of visualizing and quantifying wall motion in cerebral aneurysms. However, application of this technique is currently restricted by its limited spatial resolution. (orig.)

  4. The eigenmode analysis of human motion

    International Nuclear Information System (INIS)

    Park, Juyong; Lee, Deok-Sun; González, Marta C

    2010-01-01

    Rapid advances in modern communication technology are enabling the accumulation of large-scale, high-resolution observational data of the spatiotemporal movements of humans. Classification and prediction of human mobility based on the analysis of such data has great potential in applications such as urban planning in addition to being a subject of theoretical interest. A robust theoretical framework is therefore required to study and properly understand human motion. Here we perform the eigenmode analysis of human motion data gathered from mobile communication records, which allows us to explore the scaling properties and characteristics of human motion

  5. [Comparison of the effect of laser and magnetic therapy for pain level and the range of motion of the spine of people with osteoarthritis lower back].

    Science.gov (United States)

    Zdrodowska, Beata; Leszczyńska-Filus, Magdalena; Leszczyński, Ryszard; Błaszczyk, Jan

    2015-01-01

    Increased expression of degenerative disease of the lumbar spine is an onerous task, which reduces the efficiency of the activity and life of many populations. It is the most common cause of medical visits. In 95% of cases the cause of complaints is a destructive process in the course of degenerative intervertebral disc called a lumbar disc herniation. Protrusion of the nucleus pulposus causes severe pain and impaired muscle tone, often more chronic and difficult to master. Successful treatment of lumbar disc herniation constitutes a serious interdisciplinary problem. It is important to properly planned and carried out physiotherapy. Based on the number of non-invasive methods, to reduce muscle tension, mute pain and alleviation of inflammation. It is the treatment safe, effective, and at the same time, which is their big advantage, readily available and cheap. It is worth noting that not every method has the same efficiency. The question that the methods are effective in relieving pain and helping to effectively increase the range of motion led to a comparison of two methods - Low Level Laser Therapy (LLLT) and pulsating magnetic field therapy. The aim of the study was to compare the efficacy of LLLT and pulsating magnetic field therapy in combating pain and increase range of motion of the spine of people with degenerative spine disease of the lower back. 120 patients with diagnose lumbar disc herniation whit no nerve roots symptoms. Patients were divided into two Groups: A and B. Group A of 60 patients were subjected to laser therapy (λ=820nm, P=400mW, Ed=6-12 J/cm²) and the second Group B of 60 patients too, to pulsating magnetic fields procedures (5mT, 30 Hz, 15 minutes). Every patient before rehabilitation started and right after it has finished has undergone examination. Subjective pain assessment was carried out using a modified Laitinen questionnaire and Visual Analogue Scale of Pain intensity. Spine mobility was evaluated whit the Schober test and the

  6. On the origin of the Monoceros Ring - I. Kinematics, proper motions, and the nature of the progenitor

    Science.gov (United States)

    Guglielmo, Magda; Lane, Richard R.; Conn, Blair C.; Ho, Anna Y. Q.; Ibata, Rodrigo A.; Lewis, Geraint F.

    2018-03-01

    The Monoceros Ring (MRi) structure is an apparent stellar overdensity that has been postulated to entirely encircle the Galactic plane and has been variously described as being due to line-of-sight effects of the Galactic warp and flare or of extragalactic origin (via accretion). Despite being intensely scrutinized in the literature for more than a decade, no studies to date have been able to definitively uncover its origins. Here we use N-body simulations and a genetic algorithm to explore the parameter space for the initial position, orbital parameters, and, for the first time, the final location of a satellite progenitor. We fit our models to the latest Pan-STARRS data to determine whether an accretion scenario is capable of producing an in-plane ring-like structure matching the known parameters of the MRi. Our simulations produce streams that closely match the location, proper motion, and kinematics of the MRi structure. However, we are not able to reproduce the mass estimates from earlier studies based on Pan-STARRS data. Furthermore, in contrast to earlier studies, our best-fitting models are those for progenitors on retrograde orbits. If the MRi was produced by satellite accretion, we find that its progenitor has an initial mass upper limit of ˜1010 M⊙ and the remnant is likely located behind the Galactic bulge, making it difficult to locate observationally. While our models produce realistic MRi-like structures, we cannot definitively conclude that the MRi was produced by the accretion of a satellite galaxy.

  7. On the motion of a charged particle in the field of a magnetic monopole

    International Nuclear Information System (INIS)

    Bollini, C.G.; Ferreira, P.L.

    1977-01-01

    A quantum mechanical treatment of the motion of a charged particle in the field of fixed magnetic monopole is given based on a representation of the corresponding vector potential. The results are closely similar to those obtained in the work of T.S. Wu and C.N. Yang which stems from ideas borrowed from the mathematical fiber bundle theory. Although the present paper deals with the non-relativistic problems, it is clear that the extension to the case of a Pauli or Dirac particle can be easily done using the spinor monopole harmonics [pt

  8. The damping of spin motions in ultrathin films: Is the Landau-Lifschitz-Gilbert phenomenology applicable?

    International Nuclear Information System (INIS)

    Mills, D.L.; Arias, Rodrigo

    2006-01-01

    The Landau-Lifschitz-Gilbert (LLG) equation is used widely in device design to describe spin motions in magnetic nanoscale structures. The damping term in this equation plays an essential role in the description of the magnetization dynamics. The form of this term is simple and appealing, but it is derived through use of elementary phenomenological considerations. An important question is whether or not it provides a proper description of the damping of the magnetization in real materials. Recently, it was predicted that a mechanism called two magnon damping should contribute importantly to linewidths and consequently spin damping in ultrathin ferromagnetic films. This process yields ferromagnetic resonance (FMR) linewidths whose frequency dependence is incompatible with the linear variation expected from the Landau-Lifschitz equation. This prediction has now been confirmed experimentally. Furthermore, subsequent experimental and theoretical studies have demonstrated that the damping rate depends strongly on wave vector as well. It is thus clear that for many samples, the LLG equation fails to account for the systematics of the damping of the magnetization in ultrathin ferromagnets, at the linear response level. The paper will review the recent literature on this topic relevant to this issue. One must then inquire into the nature of a proper phenomenology to describe these materials. At the linear response level, the theory of the two magnon mechanism is sufficiently complete that one can describe the response of these systems without resort to LLG phenomenology. However, currently there is very great interest in the large amplitude response of the magnetization in magnetic nanostructures. In the view of the authors, it is difficult to envision a generally applicable extension of linear response theory into the large amplitude regime

  9. Motions and solar magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Krat, V A [AN SSSR, Leningrad. Glavnaya Astronomicheskaya Observatoriya

    1977-02-01

    Fine structure of magnetic fields in the Sun has been investigated. The data of the Soviet solar stratospheric observatory (SSO) with the telescope with a mirror first of 50 and then 100 cm in diameter obtained for the period of 1970-1973 served as material for research. The experiments give evidence of the presence of photospheric granulation with the characteristic dimension of granules below 150 km. The angular resolution of instruments does not make it possible to realize direct measurements of magnetic fields of such sizes. The indirect estimates indicate the fact that the magnetic fields of photosphere cannot be less than 10/sup 2/ Oe. A comparison of Hsub(..cap alpha..) lines with lines of metals and with the continuous spectrum shows that the least dimensions of chromosphere elements account for 500 km. Since in chromosphere density decreases drastically, than in order to suppress hydrodynamic flows fields should be of the order of 10/sup 3/ Oe. It has been concluded that the problem of the origin and evolution of the magnetic field of the Sun should be also solved by applying data on other stars.

  10. Controlling magnetic domain wall motion in the creep regime in He{sup +}-irradiated CoFeB/MgO films with perpendicular anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Herrera Diez, L., E-mail: liza.herrera-diez@ief.u-psud.fr; García-Sánchez, F.; Adam, J.-P.; Devolder, T.; Eimer, S.; El Hadri, M. S.; Ravelosona, D. [Institut d' Electronique Fondamentale, Université Paris-Sud, UMR CNRS 8622, 91405 Orsay (France); Lamperti, A.; Mantovan, R. [Laboratorio MDM, IMM-CNR, Via C. Olivetti 2, 20864 Agrate (MB) (Italy); Ocker, B. [Singulus Technology AG, Hanauer Landstrasse 103, 63796 Kahl am Main (Germany)

    2015-07-20

    This study presents the effective tuning of perpendicular magnetic anisotropy in CoFeB/MgO thin films by He{sup +} ion irradiation and its effect on domain wall motion in a low field regime. Magnetic anisotropy and saturation magnetisation are found to decrease as a function of the irradiation dose which can be related to the observed irradiation-induced changes in stoichiometry at the CoFeB/MgO interface. These changes in the magnetic intrinsic properties of the film are reflected in the domain wall dynamics at low magnetic fields (H) where irradiation is found to induce a significant decrease in domain wall velocity (v). For all irradiation doses, domain wall velocities at low fields are well described by a creep law, where Ln(v) vs. H{sup −1∕4} behaves linearly, up to a maximum field H*, which has been considered as an approximation to the value of the depinning field H{sub dep}. In turn, H* ≈ H{sub dep} is seen to increase as a function of the irradiation dose, indicating an irradiation-induced extension of the creep regime of domain wall motion.

  11. Is the Milky Way still breathing? RAVE-Gaia streaming motions

    Science.gov (United States)

    Carrillo, I.; Minchev, I.; Kordopatis, G.; Steinmetz, M.; Binney, J.; Anders, F.; Bienaymé, O.; Bland-Hawthorn, J.; Famaey, B.; Freeman, K. C.; Gilmore, G.; Gibson, B. K.; Grebel, E. K.; Helmi, A.; Just, A.; Kunder, A.; McMillan, P.; Monari, G.; Munari, U.; Navarro, J.; Parker, Q. A.; Reid, W.; Seabroke, G.; Sharma, S.; Siebert, A.; Watson, F.; Wojno, J.; Wyse, R. F. G.; Zwitter, T.

    2018-04-01

    We use data from the Radial Velocity Experiment (RAVE) and the Tycho-Gaia astrometric solution (TGAS) catalogue to compute the velocity fields yielded by the radial (VR), azimuthal (Vϕ),and vertical (Vz) components of associated Galactocentric velocity. We search in particular for variation in all three velocity components with distance above and below the disc mid-plane, as well as how each component of Vz (line-of-sight and tangential velocity projections) modifies the obtained vertical structure. To study the dependence of velocity on proper motion and distance, we use two main samples: a RAVE sample including proper motions from the Tycho-2, PPMXL, and UCAC4 catalogues, and a RAVE-TGAS sample with inferred distances and proper motions from the TGAS and UCAC5 catalogues. In both samples, we identify asymmetries in VR and Vz. Below the plane, we find the largest radial gradient to be ∂VR/∂R = -7.01 ± 0.61 km s-1 kpc-1, in agreement with recent studies. Above the plane, we find a similar gradient with ∂VR/∂R = -9.42 ± 1.77 km s-1 kpc-1. By comparing our results with previous studies, we find that the structure in Vz is strongly dependent on the adopted proper motions. Using the Galaxia Milky Way model, we demonstrate that distance uncertainties can create artificial wave-like patterns. In contrast to previous suggestions of a breathing mode seen in RAVE data, our results support a combination of bending and breathing modes, likely generated by a combination of external or internal and external mechanisms.

  12. Transverse Motion of a Particle with an Oscillating Charge and Variable Mass in a Magnetic Field

    Science.gov (United States)

    Alisultanov, Z. Z.; Ragimkhanov, G. B.

    2018-03-01

    The problem of motion of a particle with an oscillating electric charge and variable mass in an uniform magnetic field has been solved. Three laws of mass variation have been considered: linear growth, oscillations, and stepwise growth. Analytical expressions for the particle velocity at different time dependences of the particle mass are obtained. It is established that simultaneous consideration of changes in the mass and charge leads to a significant change in the particle trajectory.

  13. Multi-pulse chaotic motions of a rotor-active magnetic bearing system with time-varying stiffness

    International Nuclear Information System (INIS)

    Zhang, W.; Yao, M.H.; Zhan, X.P.

    2006-01-01

    In this paper, we investigate the Shilnikov type multi-pulse chaotic dynamics for a rotor-active magnetic bearings (AMB) system with 8-pole legs and the time-varying stiffness. The stiffness in the AMB is considered as the time-varying in a periodic form. The dimensionless equation of motion for the rotor-AMB system with the time-varying stiffness in the horizontal and vertical directions is a two-degree-of-freedom nonlinear system with quadratic and cubic nonlinearities and parametric excitation. The asymptotic perturbation method is used to obtain the averaged equations in the case of primary parametric resonance and 1/2 subharmonic resonance. It is found from the numerical results that there are the phenomena of the Shilnikov type multi-pulse chaotic motions for the rotor-AMB system. A new jumping phenomenon is discovered in the rotor-AMB system with the time-varying stiffness

  14. Magnetic Resonance Imaging–Guided versus Surrogate-Based Motion Tracking in Liver Radiation Therapy: A Prospective Comparative Study

    Energy Technology Data Exchange (ETDEWEB)

    Paganelli, Chiara, E-mail: chiara.paganelli@polimi.it [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano (Italy); Seregni, Matteo; Fattori, Giovanni [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano (Italy); Summers, Paul [Division of Radiology, Istituto Europeo di Oncologia, Milano (Italy); Bellomi, Massimo [Division of Radiology, Istituto Europeo di Oncologia, Milano (Italy); Department of Health Sciences, Università degli Studi di Milano, Milano (Italy); Baroni, Guido; Riboldi, Marco [Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano (Italy); Bioengineering Unit, CNAO Foundation, Pavia (Italy)

    2015-03-15

    Purpose: This study applied automatic feature detection on cine–magnetic resonance imaging (MRI) liver images in order to provide a prospective comparison between MRI-guided and surrogate-based tracking methods for motion-compensated liver radiation therapy. Methods and Materials: In a population of 30 subjects (5 volunteers plus 25 patients), 2 oblique sagittal slices were acquired across the liver at high temporal resolution. An algorithm based on scale invariant feature transform (SIFT) was used to extract and track multiple features throughout the image sequence. The position of abdominal markers was also measured directly from the image series, and the internal motion of each feature was quantified through multiparametric analysis. Surrogate-based tumor tracking with a state-of-the-art external/internal correlation model was simulated. The geometrical tracking error was measured, and its correlation with external motion parameters was also investigated. Finally, the potential gain in tracking accuracy relying on MRI guidance was quantified as a function of the maximum allowed tracking error. Results: An average of 45 features was extracted for each subject across the whole liver. The multi-parametric motion analysis reported relevant inter- and intrasubject variability, highlighting the value of patient-specific and spatially-distributed measurements. Surrogate-based tracking errors (relative to the motion amplitude) were were in the range 7% to 23% (1.02-3.57mm) and were significantly influenced by external motion parameters. The gain of MRI guidance compared to surrogate-based motion tracking was larger than 30% in 50% of the subjects when considering a 1.5-mm tracking error tolerance. Conclusions: Automatic feature detection applied to cine-MRI allows detailed liver motion description to be obtained. Such information was used to quantify the performance of surrogate-based tracking methods and to provide a prospective comparison with respect to MRI

  15. Dynamics of magnetic clouds in interplanetary space

    International Nuclear Information System (INIS)

    Yeh, T.

    1987-01-01

    Magnetic clouds observed in interplanetary space may be regarded as extraneous bodies immersed in the magnetized medium of the solar wind. The interface between a magnetic cloud and its surrounding medium separates the internal and external magnetic fields. Polarization currents are induced in the peripheral layer to make the ambient magnetic field tangential. The motion of a magnetic cloud through the interplanetary medium may be partitioned into a translational motion of the magnetic cloud as a whole and an expansive motion of the volume relative to the axis of the magnetic cloud. The translational motion is determined by two kinds of forces, i.e., the gravitational force exerted by the Sun, and the hydromagnetic buoyancy force exerted by the surrounding medium. On the other hand, the expansive motion is determined by the pressure gradient sustaining the gross difference between the internal and external pressures and by the self-induced magnetic force that results from the interaction among the internal currents. The force resulting from the internal and external currents is a part of the hydromagnetic buoyancy force, manifested by a thermal stress caused by the inhomogeneity of the ambient magnetic pressure

  16. Dynamics of magnetic clouds in interplanetary space

    Science.gov (United States)

    Yeh, Tyan

    1987-09-01

    Magnetic clouds observed in interplanetary space may be regarded as extraneous bodies immersed in the magnetized medium of the solar wind. The interface between a magnetic cloud and its surrounding medium separates the internal and external magnetic fields. Polarization currents are induced in the peripheral layer to make the ambient magnetic field tangential. The motion of a magnetic cloud through the interplanetary medium may be partitioned into a translational motion of the magnetic cloud as a whole and an expansive motion of the volume relative to the axis of the magnetic cloud. The translational motion is determined by two kinds of forces, i.e., the gravitational force exerted by the Sun, and the hydromagnetic buoyancy force exerted by the surrounding medium. On the other hand, the expansive motion is determined by the pressure gradient sustaining the gross difference between the internal and external pressures and by the self-induced magnetic force that results from the interaction among the internal currents. The force resulting from the internal and external currents is a part of the hydromagnetic buoyancy force, manifested by a thermal stress caused by the inhomogeneity of the ambient magnetic pressure.

  17. Topological currents in neutron stars: kicks, precession, toroidal fields, and magnetic helicity

    International Nuclear Information System (INIS)

    Charbonneau, James; Zhitnitsky, Ariel

    2010-01-01

    The effects of anomalies in high density QCD are striking. We consider a direct application of one of these effects, namely topological currents, on the physics of neutron stars. All the elements required for topological currents are present in neutron stars: degenerate matter, large magnetic fields, and parity violating processes. These conditions lead to the creation of vector currents capable of carrying momentum and inducing magnetic fields. We estimate the size of these currents for many representative states of dense matter in the neutron star and argue that they could be responsible for the large proper motion of neutron stars (kicks), the toroidal magnetic field and finite magnetic helicity needed for stability of the poloidal field, and the resolution of the conflict between type-II superconductivity and precession. Though these observational effects appear unrelated, they likely originate from the same physics — they are all P-odd phenomena that stem from a topological current generated by parity violation

  18. Motions of CMS Detector Structures as Observed by the Link Alignment System during the Test of the 4 Tesla Magnet Solenoid

    International Nuclear Information System (INIS)

    Alberdi, J.; Arce, P.; Barcala, J. M.; Calvo, E.; Ferrando, A.; Josa, M. I.; Molinero, A.; Navarrete, J.; Oller, J. C.; Yuste, C.; Calderon, A.; Gomez, G.; Gonzalez-Sanchez, F. J.; Martin-Rivero, C.; Matorras, F.; Rodrigo, T.; Ruiz-Arbol, P.; Scodellaro, L.; Sobron, M.; Vila, I.; Virto, A. L.

    2008-01-01

    This document describes results obtained from the Link Alignment System data recorded during the CMS Magnet Test. A brief description of the system is followed by the discussion of the detected relative displacements (from micro metres to centimetres) between detector elements and rotation of detector structures (from microradiants to milliradiants). Observed displacements are studied as functions of the magnetic fi eld intensity. In addition, a comparison of the reconstructed position of active element sensors with respect to their position as measured by photogrammetry is made and the reconstructed motions due to the magnetic field strength are described. (Author) 19 refs

  19. Motions of CMS Detector Structures as Observed by the Link Alignment System during the Test of the 4 Tesla Magnet Solenoid

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, J.; Arce, P.; Barcala, J. M.; Calvo, E.; Ferramdp, A.; Josa, M. I.; Molinero, A.; Navarrete, J.; Oller, J. C.; Yuste, C.; Calderon, A.; Gomez, G.; Gonzalez-Sanchez, F. J.; Martin-Rivero, C.; Matorras, F.; Rodrigo, T.; Ruiz-Arbol, P.; Scodellaro, L.; Sobron, M.; Vila, I.; Virto, A. L.

    2008-07-01

    This document describes results obtained from the Link Alignment System data recorded during the CMS Magnet Test. A brief description of the system is followed by the discussion of the detected relative displacements (from micro metres to centimetres) between detector elements and rotation of detector structures (from microradiants to milliradiants). Observed displacements are studied as functions of the magnetic fi eld intensity. In addition, a comparison of the reconstructed position of active element sensors with respect to their position as measured by photogrammetry is made and the reconstructed motions due to the magnetic field strength are described. (Author) 19 refs.

  20. Generalized quantal equation of motion

    International Nuclear Information System (INIS)

    Morsy, M.W.; Embaby, M.

    1986-07-01

    In the present paper, an attempt is made for establishing a generalized equation of motion for quantal objects, in which intrinsic self adjointness is naturally built in, independently of any prescribed representation. This is accomplished by adopting Hamilton's principle of least action, after incorporating, properly, the quantal features and employing the generalized calculus of variations, without being restricted to fixed end points representation. It turns out that our proposed equation of motion is an intrinsically self-adjoint Euler-Lagrange's differential equation that ensures extremization of the quantal action as required by Hamilton's principle. Time dependence is introduced and the corresponding equation of motion is derived, in which intrinsic self adjointness is also achieved. Reducibility of the proposed equation of motion to the conventional Schroedinger equation is examined. The corresponding continuity equation is established, and both of the probability density and the probability current density are identified. (author)

  1. Motion and twisting of magnetic particles ingested by alveolar macrophages in non-smokers and smokers: Implementation of viscoelasticity

    International Nuclear Information System (INIS)

    Moeller, Winfried; Felten, Kathrin; Kohlhaeufl, Martin; Haeussinger, Karl; Kreyling, Wolfgang G.

    2007-01-01

    Ferrimagnetic iron oxide particles were inhaled by 17 healthy volunteers (9 non-smokers, 8 smokers), and the retained particles were magnetized and detected by a SQUID. Stochastic particle transport due to cytoskeletal reorganizations within macrophages (relaxation) and directed particle motion in a weak magnetic twisting field were investigated with respect to viscous and elastic properties of the cytoskeleton. Relaxation and cytoskeletal stiffness were not influenced by cigarette smoking. Relaxation and particle twisting revealed a non-Newtonian viscosity with a pure viscous and a viscoelastic compartment. Viscous and elastic data obtained from relaxation correlated with particle twisting, indicating that the proposed simple model is a reasonable approximation of cytoskeletal mechanical properties

  2. Trapped magnetic field measurements on HTS bulk by peak controlled pulsed field magnetization

    International Nuclear Information System (INIS)

    Ida, Tetsuya; Watasaki, Masahiro; Kimura, Yosuke; Miki, Motohiro; Izumi, Mitsuru

    2010-01-01

    For the past several years, we have studied the high-temperature superconducting (HTS) synchronous motor assembled with melt-textured Gd-Ba-Cu-O bulk magnets. If the single pulse field magnetizes a bulk effectively, size of electrical motor will become small for the strong magnetic field of the HTS magnets without reducing output power of motor. In the previous study, we showed that the HTS bulk was magnetized to excellent cone-shape magnetic field distribution by using the waveform control pulse magnetization (WCPM) method. The WCPM technique made possible the active control of the waveform on which magnetic flux motion depended. We generated the pulse waveform with controlled risetime for HTS bulk magnetization to suppress the magnetic flux motion which decreases magnetization efficiency. The pulsed maximum magnetic flux density with slow risetime is not beyond the maximum magnetic flux density which is trapped by the static field magnetization. But, as for applying the pulse which has fast risetime, the magnetic flux which exceed greatly the threshold penetrates the bulk and causes the disorder of the trapped magnetic distribution. This fact suggests the possibility that the threshold at pulsed magnetization influences the dynamic magnetic flux motion. In this study, Gd-Ba-Cu-O bulk is magnetized by the controlled arbitrary trapezoidal shape pulse, of which the maximum magnetic flux density is controlled not to exceed the threshold. We will present the trapped magnetic characteristics and the technique to generate the controlled pulsed field.

  3. Measurements with magnetic field in the National Spherical Torus Experiment using the motional Stark effect with laser induced fluorescence diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Foley, E. L.; Levinton, F. M. [Nova Photonics, Inc., Princeton, New Jersey 08540 (United States)

    2013-04-15

    The motional Stark effect with laser-induced fluorescence diagnostic (MSE-LIF) has been installed and tested on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Lab. The MSE-LIF diagnostic will be capable of measuring radially resolved profiles of magnetic field magnitude or pitch angle in NSTX plasmas. The system includes a diagnostic neutral hydrogen beam and a laser which excites the n = 2 to n = 3 transition. A viewing system has been implemented which will support up to 38 channels from the plasma edge to past the magnetic axis. First measurements of MSE-LIF signals in the presence of small applied magnetic fields in neutral gas are reported.

  4. Measurements with magnetic field in the National Spherical Torus Experiment using the motional Stark effect with laser induced fluorescence diagnostic

    Science.gov (United States)

    Foley, E. L.; Levinton, F. M.

    2013-04-01

    The motional Stark effect with laser-induced fluorescence diagnostic (MSE-LIF) has been installed and tested on the National Spherical Torus Experiment (NSTX) at the Princeton Plasma Physics Lab. The MSE-LIF diagnostic will be capable of measuring radially resolved profiles of magnetic field magnitude or pitch angle in NSTX plasmas. The system includes a diagnostic neutral hydrogen beam and a laser which excites the n = 2 to n = 3 transition. A viewing system has been implemented which will support up to 38 channels from the plasma edge to past the magnetic axis. First measurements of MSE-LIF signals in the presence of small applied magnetic fields in neutral gas are reported.

  5. Dosimetric Impact of Intrafractional Patient Motion in Pediatric Brain Tumor Patients

    International Nuclear Information System (INIS)

    Beltran, Chris; Trussell, John; Merchant, Thomas E.

    2010-01-01

    The purpose of this study was to determine the dosimetric consequences of intrafractional patient motion on the clinical target volume (CTV), spinal cord, and optic nerves for non-sedated pediatric brain tumor patients. The patients were immobilized for treatment using a customized thermoplastic full-face mask and bite-block attached to an array of reflectors. The array was optically tracked by infra-red cameras at a frequency of 10 Hz. Patients were localized based on skin/mask marks and weekly films were taken to ensure proper setup. Before each noncoplanar field was delivered, the deviation from baseline of the array was recorded. The systematic error (SE) and random error (RE) were calculated. Direct simulation of the intrafractional motion was used to quantify the dosimetric changes to the targets and critical structures. Nine patients utilizing the optical tracking system were evaluated. The patient cohort had a mean of 31 ± 1.5 treatment fractions; motion data were acquired for a mean of 26 ± 6.2 fractions. The mean age was 15.6 ± 4.1 years. The SE and RE were 0.4 and 1.1 mm in the posterior-anterior, 0.5 and 1.0 mm in left-right, and 0.6 and 1.3 mm in superior-inferior directions, respectively. The dosimetric effects of the motion on the CTV were negligible; however, the dose to the critical structures was increased. Patient motion during treatment does affect the dose to critical structures, therefore, planning risk volumes are needed to properly assess the dose to normal tissues. Because the motion did not affect the dose to the CTV, the 3-mm PTV margin used is sufficient to account for intrafractional motion, given the patient is properly localized at the start of treatment.

  6. Synchronous motion of a relativistic particles in the wave propagating at the angle to a magnetic field

    International Nuclear Information System (INIS)

    Milant'ev, V.P.

    1996-01-01

    It is shown that within the transverse or the longitudinal wave propagating at the angle to the magnetic field there is a specific mode of motion of relativistic particle called as a synchronous one where the condition of a particle resonance with the wave is realized with increasing accuracy with increase of particle energy. A trend to the unlimited acceleration is detected in a synchronous mode of the Cherenkov resonance. 21 refs

  7. Theoretical study of ferromagnetic resonance in exchange - coupled magnetic / nonmagnetic / magnetic multilayer structure

    International Nuclear Information System (INIS)

    Oezdogan, K.; Oezdemir, M.; Yalcin, O.; Aktas, B.

    2002-01-01

    The dispersion relation on ferromagnetic films was calculation by using torque equation of motion with a damping term. The total energy including zeeman, demagnetizing and anisotropy energy terms was used to get ferromagnetic resonance frequency for both uniform and higher order spin wave modes. In antiferromagnetic films, the torque equation of motion for each sub-lattice were written to derive an expression for the dispersion relation. The magnetic trilayer system under investigation consist of two ferromagnetic layers separated by a nonmagnetic layer. The dispersion relation of magnetic/nonmagnetic/magnetic three layers is calculated by using Landau-Lifshitz dynamic equation of motion for the magnetization with interlayer exchange energy. As for the exchange-coupled resonance of ferromagnetic resonance (FMR), the theoretical study has been calculated for both symmetrical and asymmetrical structures. In this systems, the exchange-coupling parameter A 12 between neighboring layers was used to get resonance fields as a function of the angle between the magnetization vectors of each magnetic layers

  8. Induced motion of domain walls in multiferroics with quadratic interaction

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimchuk, Victor S., E-mail: viktor.gera@gmail.com [National Technical University of Ukraine “Kyiv Polytechnic Institute”, Peremohy Avenue 37, 03056 Kiev (Ukraine); Shitov, Anatoliy A., E-mail: shitov@mail.ru [Donbass National Academy of Civil Engineering, Derzhavina Street 2, 86123 Makeevka, Donetsk Region (Ukraine)

    2013-10-15

    We theoretically study the dynamics of 180-degree domain wall of the ab-type in magnetic materials with quadratic magnetoelectric interaction in external alternating magnetic and electric fields. The features of the oscillatory and translational motions of the domain walls and stripe structures depending on the parameters of external fields and characteristics of the multiferroics are discussed. The possibility of the domain walls drift in a purely electric field is established. - Highlights: • We study DW and stripe DS in multiferroics with quadratic magnetoelectric interaction. • We build up the theory of oscillatory and translational (drift) DW and DS motion. • DW motion can be caused by crossed alternating electric and magnetic fields. • DW motion can be caused by alternating “pure” electric field. • DW drift velocity is formed by the AFM and Dzyaloshinskii interaction terms.

  9. Facial motion parameter estimation and error criteria in model-based image coding

    Science.gov (United States)

    Liu, Yunhai; Yu, Lu; Yao, Qingdong

    2000-04-01

    Model-based image coding has been given extensive attention due to its high subject image quality and low bit-rates. But the estimation of object motion parameter is still a difficult problem, and there is not a proper error criteria for the quality assessment that are consistent with visual properties. This paper presents an algorithm of the facial motion parameter estimation based on feature point correspondence and gives the motion parameter error criteria. The facial motion model comprises of three parts. The first part is the global 3-D rigid motion of the head, the second part is non-rigid translation motion in jaw area, and the third part consists of local non-rigid expression motion in eyes and mouth areas. The feature points are automatically selected by a function of edges, brightness and end-node outside the blocks of eyes and mouth. The numbers of feature point are adjusted adaptively. The jaw translation motion is tracked by the changes of the feature point position of jaw. The areas of non-rigid expression motion can be rebuilt by using block-pasting method. The estimation approach of motion parameter error based on the quality of reconstructed image is suggested, and area error function and the error function of contour transition-turn rate are used to be quality criteria. The criteria reflect the image geometric distortion caused by the error of estimated motion parameters properly.

  10. KINERJA PENGELOLAAN LIMBAH HOTEL PESERTA PROPER DAN NON PROPER DI KABUPATEN BADUNG, PROVINSI BALI

    Directory of Open Access Journals (Sweden)

    Putri Nilakandi Perdanawati Pitoyo

    2016-07-01

    Full Text Available Bali tourism development can lead to positive and negative impacts that threatening environmental sustainability. This research evaluates the hotel performance of the waste management that includes management of waste water, emission, hazardous, and solid waste by hotel that participate at PROPER and non PROPER. Research using qualitative descriptive method. Not all of non PROPER doing test on waste water quality, chimney emissions quality, an inventory of hazardous waste and solid waste sorting. Wastewater discharge of PROPER hotels ranged from 290.9 to 571.8 m3/day and non PROPER ranged from 8.4 to 98.1 m3/day with NH3 parameter values that exceed the quality standards. The quality of chimney emissions were still below the quality standard. The volume of the hazardous waste of PROPER hotels ranged from 66.1 to 181.9 kg/month and non PROPER ranged from 5.003 to 103.42 kg/month. Hazardous waste from the PROPER hotel which has been stored in the TPS hazardous waste. The volume of the solid waste of PROPER hotel ranged from 342.34 to 684.54 kg/day and non PROPER ranged from 4.83 to 181.51 kg/day. The PROPER and non PROPER hotel not sort the solid waste. The hotel performance in term of wastewater management, emission, hazardous, and solid waste is better at the PROPER hotel compared to non PROPER participants.

  11. Drift motion of a charged particle in the crossed axial magnetic and radial electric fields, and the electric field of a rotating potential wave

    International Nuclear Information System (INIS)

    Eliseev, Yu.N.; Stepanov, K.N.

    1983-01-01

    In the drift motion approximation solution of the problem is obtained on the motion of a nonrelativistic charged particle in the crossed axial magnetic and radial electric fields, and the electric field of a rotating potential wave under cherenkov and modified cyclotron resonances. The static radial electric field potential is supposed to be close to the parabolic one. The drift motion equations and their integrals are preseOted. The experimentally obtained effect of plasma ionic component division in the crossed fields under the excitation of ion cyclotron oscillations is explained with the help of the theory developed in the paper

  12. Designing a compact MRI motion phantom

    Directory of Open Access Journals (Sweden)

    Schmiedel Max

    2016-09-01

    Full Text Available Even today, dealing with motion artifacts in magnetic resonance imaging (MRI is a challenging task. Image corruption due to spontaneous body motion complicates diagnosis. In this work, an MRI phantom for rigid motion is presented. It is used to generate motion-corrupted data, which can serve for evaluation of blind motion compensation algorithms. In contrast to commercially available MRI motion phantoms, the presented setup works on small animal MRI systems. Furthermore, retrospective gating is performed on the data, which can be used as a reference for novel motion compensation approaches. The motion of the signal source can be reconstructed using motor trigger signals and be utilized as the ground truth for motion estimation. The proposed setup results in motion corrected images. Moreover, the importance of preprocessing the MRI raw data, e.g. phase-drift correction, is demonstrated. The gained knowledge can be used to design an MRI phantom for elastic motion.

  13. Free-breathing whole-heart 3D cine magnetic resonance imaging with prospective respiratory motion compensation.

    Science.gov (United States)

    Moghari, Mehdi H; Barthur, Ashita; Amaral, Maria E; Geva, Tal; Powell, Andrew J

    2018-07-01

    To develop and validate a new prospective respiratory motion compensation algorithm for free-breathing whole-heart 3D cine steady-state free precession (SSFP) imaging. In a 3D cine SSFP sequence, 4 excitations per cardiac cycle are re-purposed to prospectively track heart position. Specifically, their 1D image is reconstructed and routed into the scanner's standard diaphragmatic navigator processing system. If all 4 signals are in end-expiration, cine image data from the entire cardiac cycle is accepted for image reconstruction. Prospective validation was carried out in patients (N = 17) by comparing in each a conventional breath-hold 2D cine ventricular short-axis stack and a free-breathing whole-heart 3D cine data set. All 3D cine SSFP acquisitions were successful and the mean scan time was 5.9 ± 2.7 min. Left and right ventricular end-diastolic, end-systolic, and stroke volumes by 3D cine SSFP were all larger than those from 2D cine SSFP. This bias was 3D cine images had a lower ventricular blood-to-myocardium contrast ratio, contrast-to-noise ratio, mass, and subjective quality score. The novel prospective respiratory motion compensation method for 3D cine SSFP imaging was robust and efficient and yielded slightly larger ventricular volumes and lower mass compared to breath-hold 2D cine imaging. Magn Reson Med 80:181-189, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  14. Tracking the Magnetic Flux in and Around Sunspots

    Energy Technology Data Exchange (ETDEWEB)

    Sheeley, N. R. Jr.; Stauffer, J. R.; Thomassie, J. C.; Warren, H. P., E-mail: solsheeley@verizon.net, E-mail: harry.warren@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)

    2017-02-10

    We have developed a procedure for tracking sunspots observed by the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory and for making curvature-corrected space/time maps of the associated line-of-sight magnetic field and continuum intensity. We apply this procedure to 36 sunspots, each observed continuously for nine days around its central meridian passage time, and find that the proper motions separate into two distinct components depending on their speeds. Fast (∼3–5 km s{sup −1}) motions, comparable to Evershed flows, are produced by weak vertical fluctuations of the horizontal canopy field and recur on a timescale of 12–20 min. Slow (∼0.3–0.5 km s{sup −1}) motions diverge from a sunspot-centered ring whose location depends on the size of the sunspot, occurring in the mid-penumbra for large sunspots and at the outer edge of the penumbra for small sunspots. The slow ingoing features are contracting spokes of a quasi-vertical field of umbral polarity. These inflows disappear when the sunspot loses its penumbra, and may be related to inward-moving penumbral grain. The slow outgoing features may have either polarity depending on whether they originate from quasi-vertical fields of umbral polarity or from the outer edge of the canopy. When a sunspot decays, the penumbra and canopy disappear, and the moat becomes filled with slow outflows of umbral polarity. We apply our procedure to decaying sunspots, to long-lived sunspots, and to numerical simulations of a long-lived sunspot by Rempel.

  15. Motion-induced eddy current thermography for high-speed inspection

    Directory of Open Access Journals (Sweden)

    Jianbo Wu

    2017-08-01

    Full Text Available This letter proposes a novel motion-induced eddy current based thermography (MIECT for high-speed inspection. In contrast to conventional eddy current thermography (ECT based on a time-varying magnetic field created by an AC coil, the motion-induced eddy current is induced by the relative motion between magnetic field and inspected objects. A rotating magnetic field created by three-phase windings is used to investigate the heating principle and feasibility of the proposed method. Firstly, based on Faraday’s law the distribution of MIEC is investigated, which is then validated by numerical simulation. Further, experimental studies are conducted to validate the proposed method by creating rotating magnetic fields at different speeds from 600 rpm to 6000 rpm, and it is verified that rotating speed will increase MIEC intensity and thereafter improve the heating efficiency. The conclusion can be preliminarily drawn that the proposed MIECT is a platform suitable for high-speed inspection.

  16. Quasi-discrete particle motion in an externally imposed, ordered structure in a dusty plasma at high magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Edward, E-mail: etjr@auburn.edu; Konopka, Uwe; Lynch, Brian; Adams, Stephen; LeBlanc, Spencer [Physics Department, Auburn University, Auburn, Alabama 36849 (United States); Merlino, Robert L. [Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242 (United States); Rosenberg, Marlene [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

    2015-11-15

    Dusty plasmas have been studied in argon, radio frequency (rf) glow discharge plasmas at magnetic fields up to 2.5 T where the electrons and ions are strongly magnetized. Plasmas are generated between two parallel plate electrodes where the lower, powered electrode is solid and the upper electrode supports a dual mesh consisting of #24 brass and #30 aluminum wire cloth. In this experiment, we study the formation of imposed ordered structures and particle dynamics as a function of magnetic field. Through observations of trapped particles and the quasi-discrete (i.e., “hopping”) motion of particles between the trapping locations, it is possible to make a preliminary estimate of the potential structure that confines the particles to a grid structure in the plasma. This information is used to gain insight into the formation of the imposed grid pattern of the dust particles in the plasma.

  17. Quantification of Esophageal Tumor Motion on Cine-Magnetic Resonance Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Lever, Frederiek M.; Lips, Irene M.; Crijns, Sjoerd P.M.; Reerink, Onne; Lier, Astrid L.H.M.W. van; Moerland, Marinus A.; Vulpen, Marco van; Meijer, Gert J., E-mail: g.j.meijer@umcutrecht.nl

    2014-02-01

    Purpose: To quantify the movement of esophageal tumors noninvasively on cine-magnetic resonance imaging (MRI) by use of a semiautomatic method to visualize tumor movement directly throughout multiple breathing cycles. Methods and Materials: Thirty-six patients with esophageal tumors underwent MRI. Tumors were located in the upper (8), middle (7), and lower (21) esophagus. Cine-MR images were collected in the coronal and sagittal plane during 60 seconds at a rate of 2 Hz. An adaptive correlation filter was used to automatically track a previously marked reference point. Tumor movement was measured in the craniocaudal (CC), left–right (LR), and anteroposterior (AP) directions and its relationship along the longitudinal axis of the esophagus was investigated. Results: Tumor registration within the individual images was typically done at a millisecond time scale. The mean (SD) peak-to-peak displacements in the CC, AP, and LR directions were 13.3 (5.2) mm, 4.9 (2.5) mm, and 2.7 (1.2) mm, respectively. The bandwidth to cover 95% of excursions from the mean position (c95) was also calculated to exclude outliers caused by sporadic movements. The mean (SD) c95 values were 10.1 (3.8) mm, 3.7 (1.9) mm, and 2.0 (0.9) mm in the CC, AP, and LR dimensions. The end-exhale phase provided a stable position in the respiratory cycle, compared with more variety in the end-inhale phase. Furthermore, lower tumors showed more movement than did higher tumors in the CC and AP directions. Conclusions: Intrafraction tumor movement was highly variable between patients. Tumor position proved the most stable during the respiratory cycle in the end-exhale phase. A better understanding of tumor motion makes it possible to individualize radiation delivery strategies accordingly. Cine-MRI is a successful noninvasive modality to analyze motion for this purpose in the future.

  18. Quantification of Esophageal Tumor Motion on Cine-Magnetic Resonance Imaging

    International Nuclear Information System (INIS)

    Lever, Frederiek M.; Lips, Irene M.; Crijns, Sjoerd P.M.; Reerink, Onne; Lier, Astrid L.H.M.W. van; Moerland, Marinus A.; Vulpen, Marco van; Meijer, Gert J.

    2014-01-01

    Purpose: To quantify the movement of esophageal tumors noninvasively on cine-magnetic resonance imaging (MRI) by use of a semiautomatic method to visualize tumor movement directly throughout multiple breathing cycles. Methods and Materials: Thirty-six patients with esophageal tumors underwent MRI. Tumors were located in the upper (8), middle (7), and lower (21) esophagus. Cine-MR images were collected in the coronal and sagittal plane during 60 seconds at a rate of 2 Hz. An adaptive correlation filter was used to automatically track a previously marked reference point. Tumor movement was measured in the craniocaudal (CC), left–right (LR), and anteroposterior (AP) directions and its relationship along the longitudinal axis of the esophagus was investigated. Results: Tumor registration within the individual images was typically done at a millisecond time scale. The mean (SD) peak-to-peak displacements in the CC, AP, and LR directions were 13.3 (5.2) mm, 4.9 (2.5) mm, and 2.7 (1.2) mm, respectively. The bandwidth to cover 95% of excursions from the mean position (c95) was also calculated to exclude outliers caused by sporadic movements. The mean (SD) c95 values were 10.1 (3.8) mm, 3.7 (1.9) mm, and 2.0 (0.9) mm in the CC, AP, and LR dimensions. The end-exhale phase provided a stable position in the respiratory cycle, compared with more variety in the end-inhale phase. Furthermore, lower tumors showed more movement than did higher tumors in the CC and AP directions. Conclusions: Intrafraction tumor movement was highly variable between patients. Tumor position proved the most stable during the respiratory cycle in the end-exhale phase. A better understanding of tumor motion makes it possible to individualize radiation delivery strategies accordingly. Cine-MRI is a successful noninvasive modality to analyze motion for this purpose in the future

  19. Magnetic translator bearings

    Science.gov (United States)

    Hockney, Richard L. (Inventor); Downer, James R. (Inventor); Eisenhaure, David B. (Inventor); Hawkey, Timothy J. (Inventor); Johnson, Bruce G. (Inventor)

    1990-01-01

    A magnetic bearing system for enabling translational motion includes a carriage and a shaft for movably supporting the carriage; a first magnetic bearing fixed to one of the carriage and shaft and slidably received in a first channel of the other of the carriage and shaft. The first channel is generally U shaped with two side walls and a back wall. The magnetic bearing includes a pair of spaced magnetic pole pieces, each pole piece having a pair of electromagnetic coils mounted on poles on opposite ends of the pole piece proximate the side walls, and a third electromagnetic coil mounted on a pole of the pole piece proximate the backwall; a motion sensor for sensing translational motion along two axes and rotationally about three axes of the carriage and shaft relative to each other; and a correction circuit responsive to the sensor for generating a correction signal to drive the coils to compensate for any misalignment sensed between the carriage and the shaft.

  20. Relation of twist of magnetic force tube and flare magnetic field

    International Nuclear Information System (INIS)

    Tanaka, H.

    1978-01-01

    The configuration of magnetic field and its development in the regions of big flare were investigated to study the features of magnetic force tubes. The photographs of delta type solar spots taken at Mt. Wilson Observatory were selected. 94 percent of the delta type spots belong to the class B activity or more active class. The features of delta type spots are the reverse configuration and the shear motion. The reverse configuration is divided into the p/f configuration and the f/p configuration. The shear motion is divided into the normal motion, the reverse motion, and the indefinite motion. Vortex structures appeared around the solar spots of reverse configuration showing normal motion. The relation among the direction of twist, reverse configuration and the direction of shear motion was deduced. In the region of normal motion, the p/f configuration corresponds to the reverse S type vortices and the f/p configuration to S type. In the region of reverse motion, the p/f configuration corresponds to the S type vortices and the f/p corresponds to the reverse S type vortices. The mechanism of development of delta type solar spots is discussed. (Kato, T.)

  1. Compensation for incoherent ground motion

    International Nuclear Information System (INIS)

    Shigeru, Takeda; Hiroshi, Matsumoto; Masakazu, Yoshioka; Yasunori, Takeuchi; Kikuo, Kudo; Tsuneya, Tsubokawa; Mitsuaki, Nozaki; Kiyotomo, Kawagoe

    1999-01-01

    The power spectrum density and coherence function for ground motions are studied for the construction of the next generation electron-positron linear collider. It should provide a center of mass energy between 500 GeV-1 TeV with luminosity as high as 10 33 to 10 34 cm -2 sec -1 . Since the linear collider has a relatively slow repetition rate, large number of particles and small sizes of the beam should be generated and preserved in the machine to obtain the required high luminosity. One of the most critical parameters is the extremely small vertical beam size at the interaction point, thus a proper alignment system for the focusing and accelerating elements of the machine is necessary to achieve the luminosity. We describe recent observed incoherent ground motions and an alignment system to compensate the distortion by the ground motions. (authors)

  2. An effect of the fringing field in sector bending magnets: the coupling of the transverse planes in the solutions of the equation of motion at second-order

    International Nuclear Information System (INIS)

    Roy, G.

    1988-11-01

    Second order coupling terms for sector bending magnets due to edge effects at high energy are reviewed. Motion in the horizontal plane (bending plane) and in the vertical (nonbending) plane is considered. The model of Heaviside's function is outlined. The case of the complete bending magnet is treated. Three second order coupling terms between the vertical and horizontal planes in a complete bending magnet are found. Their origin is the fringing field, i.e., the intensity difference of the magnetic field between the outside and the inside of the magnet

  3. Estimation of fetal volume by magnetic resonance imaging and stereology.

    Science.gov (United States)

    Roberts, N; Garden, A S; Cruz-Orive, L M; Whitehouse, G H; Edwards, R H

    1994-11-01

    The current methods to monitor fetal growth in utero are based on ultrasound image measurements which, lacking a proper sampling methodology, may be biased to unknown degrees. The Cavalieri method of stereology guarantees the accurate estimation of the volume of an arbitrary object from a few systematic sections. Non-invasive scanning methods, and magnetic resonance imaging (MRI) in particular, are valuable tools to provide the necessary sections, and therefore offer interesting possibilities for unbiased quantification. This paper describes how to estimate fetal volume in utero with a coefficient of error of less than 5% in less than 5 min, from three or four properly sampled MRI scans. MRI was chosen because it does not use ionizing radiations on the one hand, and it offers a good image quality on the other. The impact of potential sources of bias such as fetal motion, chemical shift and partial voluming artefacts is discussed. The methods are illustrated on four subjects monitored between weeks 28 and 40 of gestation.

  4. Electromagnetic radiation of charged particles in stochastic motion

    Energy Technology Data Exchange (ETDEWEB)

    Harko, Tiberiu [Babes-Bolyai University, Department of Physics, Cluj-Napoca (Romania); University College London, Department of Mathematics, London (United Kingdom); Mocanu, Gabriela [Astronomical Institute of the Romanian Academy, Cluj-Napoca (Romania)

    2016-03-15

    The study of the Brownian motion of a charged particle in electric and magnetic fields has many important applications in plasma and heavy ions physics, as well as in astrophysics. In the present paper we consider the electromagnetic radiation properties of a charged non-relativistic particle in the presence of electric and magnetic fields, of an exterior non-electromagnetic potential, and of a friction and stochastic force, respectively. We describe the motion of the charged particle by a Langevin and generalized Langevin type stochastic differential equation. We investigate in detail the cases of the Brownian motion with or without memory in a constant electric field, in the presence of an external harmonic potential, and of a constant magnetic field. In all cases the corresponding Langevin equations are solved numerically, and a full description of the spectrum of the emitted radiation and of the physical properties of the motion is obtained. The power spectral density of the emitted power is also obtained for each case, and, for all considered oscillating systems, it shows the presence of peaks, corresponding to certain intervals of the frequency. (orig.)

  5. Inference of core barrel motion from neutron noise spectral density. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, J.C.; Shahrokhi, F.; Kryter, R.C.

    1977-03-15

    A method was developed for inference of core barrel motion from the following statistical descriptors: cross-power spectral density, autopower spectral density, and amplitude probability density. To quantify the core barrel motion in a typical pressurized water reactor (PWR), a scale factor was calculated in both one- and two-dimensional geometries using forward, variational, and perturbation methods of discrete ordinates neutron transport. A procedure for selection of the proper frequency band limits for the statistical descriptors was developed. It was found that although perturbation theory is adequate for the calculation of the scale factor, two-dimensional geometric effects are important enough to rule out the use of a one-dimensional approximation for all but the crudest calculations. It was also found that contributions of gamma rays can be ignored and that the results are relatively insensitive to the cross-section set employed. The proper frequency band for the statistical descriptors is conveniently determined from the coherence and phase information from two ex-core power range neutron monitors positioned diametrically across the reactor vessel. Core barrel motion can then be quantified from the integral of the band-limited cross-power spectral density of two diametrically opposed ex-core monitors or, if the coherence between the pair is greater than or equal to 0.7, from a properly band-limited amplitude probability density function. Wide-band amplitude probability density functions were demonstrated to yield erroneous estimates for the magnitude of core barrel motion.

  6. Lagrangian Description of Nonadiabatic Particle Motion in Spherical Tori

    Energy Technology Data Exchange (ETDEWEB)

    R.B. White; Yu.V. Yakovenko; Ya.I. Kolesnichenko

    2002-06-21

    The ability of a device to provide adiabatic motion of charged particles is crucial for magnetic confinement. As the magnetic field in the present-day spherical tori, e.g., MAST and NSTX, is much lower than in the conventional tokamaks, effects of the finite Larmor radius (FLR) on the motion of fast ions are of importance in these devices, affecting the stochasticity threshold for the interaction of the ions with electromagnetic perturbations. In addition, FLR by itself may result in non-conservation (jumps) of the magnetic moment of particles [4]. In this work we propose a Lagrangian approach to description of the resonant collisionless motion of charged particles under a perturbation, allowing for FLR. The work generalizes results of Ref. [1], where only time-independent perturbations were considered. The approach is used to find the stochasticity thresholds for the Goldston-White-Boozer (GWB) diffusion [2] and the cyclotron-resonance-induced (CRI) diffusion (for the case of the firs t cyclotron resonance, the latter was discovered in Ref. [3]). In addition, a new expression for the magnetic moment variation caused by FLR is found.

  7. Lagrangian Description of Nonadiabatic Particle Motion in Spherical Tori

    International Nuclear Information System (INIS)

    White, R.B.; Yakovenko, Yu.V.; Kolesnichenko, Ya.I.

    2002-01-01

    The ability of a device to provide adiabatic motion of charged particles is crucial for magnetic confinement. As the magnetic field in the present-day spherical tori, e.g., MAST and NSTX, is much lower than in the conventional tokamaks, effects of the finite Larmor radius (FLR) on the motion of fast ions are of importance in these devices, affecting the stochasticity threshold for the interaction of the ions with electromagnetic perturbations. In addition, FLR by itself may result in non-conservation (jumps) of the magnetic moment of particles [4]. In this work we propose a Lagrangian approach to description of the resonant collisionless motion of charged particles under a perturbation, allowing for FLR. The work generalizes results of Ref. [1], where only time-independent perturbations were considered. The approach is used to find the stochasticity thresholds for the Goldston-White-Boozer (GWB) diffusion [2] and the cyclotron-resonance-induced (CRI) diffusion (for the case of the first cyclotron resonance, the latter was discovered in Ref. [3]). In addition, a new expression for the magnetic moment variation caused by FLR is found

  8. Comparison of transient severe motion in gadoxetate disodium and gadopentetate dimeglumine-enhanced MRI. Effect of modified breath-holding method

    International Nuclear Information System (INIS)

    Song, Ji Soo; Choi, Eun Jung; Park, Eun Hae; Lee, Ju-Hyung

    2018-01-01

    To compare the occurrence of transient severe motion (TSM) between gadoxetate disodium- and gadopentetate dimeglumine-enhanced MRI and between gadoxetate disodium-enhanced MRI scans obtained with and without the application of a modified breath-holding technique. We reviewed 80 patients who underwent two magnetic resonance examinations (gadoxetate disodium-enhanced MRI and gadopentetate dimeglumine-enhanced MRI) with the application of a modified breath-holding technique (dual group). This group was compared with 100 patients who underwent gadoxetate disodium-enhanced MRI without the application of the modified breath-holding technique (single group). Patient risk factors and motion scores (1 [none] to 5 [non-diagnostic]) for each dynamic-phase imaging were analysed. In the dual group, mean motion scores did not differ significantly between gadoxetate disodium- and gadopentetate dimeglumine-enhanced MRI (p=0.096-0.807) in any phase. However, in all phases except the late dynamic phase, mean motion scores of the dual group were significantly lower than those in the single group. TSM incidence did not differ significantly between gadoxetate disodium- and gadopentetate dimeglumine-enhanced MRI in the dual group (3.8% vs. 1.3%, p=0.620). With proper application of the modified breath-holding technique, TSM occurrence with gadoxetate disodium-enhanced MRI was comparable to that associated with gadopentetate dimeglumine-enhanced MRI. (orig.)

  9. Comparison of transient severe motion in gadoxetate disodium and gadopentetate dimeglumine-enhanced MRI. Effect of modified breath-holding method

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ji Soo; Choi, Eun Jung; Park, Eun Hae [Chonbuk National University Medical School and Hospital, Department of Radiology, Jeonju (Korea, Republic of); Research Institute of Clinical Medicine of Chonbuk National University, Jeonju (Korea, Republic of); Biomedical Research Institute of Chonbuk National University Hospital, Jeonju (Korea, Republic of); Lee, Ju-Hyung [Chonbuk National University Medical School, Department of Preventive Medicine, Jeonju (Korea, Republic of)

    2018-03-15

    To compare the occurrence of transient severe motion (TSM) between gadoxetate disodium- and gadopentetate dimeglumine-enhanced MRI and between gadoxetate disodium-enhanced MRI scans obtained with and without the application of a modified breath-holding technique. We reviewed 80 patients who underwent two magnetic resonance examinations (gadoxetate disodium-enhanced MRI and gadopentetate dimeglumine-enhanced MRI) with the application of a modified breath-holding technique (dual group). This group was compared with 100 patients who underwent gadoxetate disodium-enhanced MRI without the application of the modified breath-holding technique (single group). Patient risk factors and motion scores (1 [none] to 5 [non-diagnostic]) for each dynamic-phase imaging were analysed. In the dual group, mean motion scores did not differ significantly between gadoxetate disodium- and gadopentetate dimeglumine-enhanced MRI (p=0.096-0.807) in any phase. However, in all phases except the late dynamic phase, mean motion scores of the dual group were significantly lower than those in the single group. TSM incidence did not differ significantly between gadoxetate disodium- and gadopentetate dimeglumine-enhanced MRI in the dual group (3.8% vs. 1.3%, p=0.620). With proper application of the modified breath-holding technique, TSM occurrence with gadoxetate disodium-enhanced MRI was comparable to that associated with gadopentetate dimeglumine-enhanced MRI. (orig.)

  10. An efficient sequence for fetal brain imaging at 3T with enhanced T1 contrast and motion robustness.

    Science.gov (United States)

    Ferrazzi, Giulio; Price, Anthony N; Teixeira, Rui Pedro A G; Cordero-Grande, Lucilio; Hutter, Jana; Gomes, Ana; Padormo, Francesco; Hughes, Emer; Schneider, Torben; Rutherford, Mary; Kuklisova Murgasova, Maria; Hajnal, Joseph V

    2018-07-01

    Ultrafast single-shot T 2 -weighted images are common practice in fetal MR exams. However, there is limited experience with fetal T 1 -weighted acquisitions. This study aims at establishing a robust framework that allows fetal T 1 -weighted scans to be routinely acquired in utero at 3T. A 2D gradient echo sequence with an adiabatic inversion was optimized to be robust to fetal motion and maternal breathing optimizing grey/white matter contrast at the same time. This was combined with slice to volume registration and super resolution methods to produce volumetric reconstructions. The sequence was tested on 22 fetuses. Optimized grey/white matter contrast and robustness to fetal motion and maternal breathing were achieved. Signal from cerebrospinal fluid (CSF) and amniotic fluid was nulled and 0.75 mm isotropic anatomical reconstructions of the fetal brain were obtained using slice-to-volume registration and super resolution techniques. Total acquisition time for a single stack was 56 s, all acquired during free breathing. Enhanced sensitivity to normal anatomy and pathology with respect to established methods is demonstrated. A direct comparison with a 3D spoiled gradient echo sequence and a controlled motion experiment run on an adult volunteer are also shown. This paper describes a robust framework to perform T 1 -weighted acquisitions and reconstructions of the fetal brain in utero. Magn Reson Med 80:137-146, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic

  11. Two- and three-dimensional magnetoinductive particle codes with guiding center electron motion

    International Nuclear Information System (INIS)

    Geary, J.L.; Tajima, T.; Leboeuf, J.N.; Zaidman, E.G.; Han, J.H.

    1986-07-01

    A magnetoinductive (Darwin) particle simulation model developed for examining low frequency plasma behavior with large time steps is presented. Electron motion perpendicular to the magnetic field is treated as massless keeping only the guiding center motion. Electron motion parallel to the magnetic field retains full inertial effects as does the ion motion. This model has been implemented in two and three dimensions. Computational tests of the equilibrium properties of the code are compared with linear theory and the fluctuation dissipation theorem. This code has been applied to the problems of Alfven wave resonance heating and twist-kink modes

  12. Motion of particles and spin in polarized media

    International Nuclear Information System (INIS)

    Silenko, A.Ya.

    2003-01-01

    The equations of the particle and spin motion in media with polarized electrons placed in external fields are found. The exchange interaction affects the motion of electrons and their spin, and the annihilation interaction affects the motion of positrons and their spin. The second-order terms in spin are taken into account for particles with spin S ≥ 1. The found equations can be used for the description of the particle and spin motion in both magnetic and nonmagnetic media [ru

  13. Domain-walls motion in glass-coated CoFeSiB amorphous microwires

    Energy Technology Data Exchange (ETDEWEB)

    Antonov, A.S. E-mail: as.antonov@mtu-net.ru; Buznikov, N.A.; Granovsky, A.B.; Joura, A.V.; Rakhmanov, A.L.; Yakunin, A.M

    2002-08-01

    A method for observation of domain-walls motion in amorphous microwires with circular magnetic anisotropy is proposed. Using the method, the magnetization reversal of glass-coated Co-based microwires induced by current pulses of high amplitude is studied. The magnetization reversal is shown to occur due to the nucleation of the domain walls at the sample ends and their subsequent motion along the microwire. The dependencies of the domain-wall velocity on the current pulse amplitude and a longitudinal DC magnetic field are measured. A model describing main features of experimental data is presented.

  14. Domain-walls motion in glass-coated CoFeSiB amorphous microwires

    International Nuclear Information System (INIS)

    Antonov, A.S.; Buznikov, N.A.; Granovsky, A.B.; Joura, A.V.; Rakhmanov, A.L.; Yakunin, A.M.

    2002-01-01

    A method for observation of domain-walls motion in amorphous microwires with circular magnetic anisotropy is proposed. Using the method, the magnetization reversal of glass-coated Co-based microwires induced by current pulses of high amplitude is studied. The magnetization reversal is shown to occur due to the nucleation of the domain walls at the sample ends and their subsequent motion along the microwire. The dependencies of the domain-wall velocity on the current pulse amplitude and a longitudinal DC magnetic field are measured. A model describing main features of experimental data is presented

  15. Design and experimental investigation of a magnetically coupled vibration energy harvester using two inverted piezoelectric cantilever beams for rotational motion

    International Nuclear Information System (INIS)

    Zou, Hong-Xiang; Zhang, Wen-ming; Li, Wen-Bo; Wei, Ke-Xiang; Gao, Qiu-Hua; Peng, Zhi-Ke; Meng, Guang

    2017-01-01

    Highlights: • A magnetically coupled two-degree-of-freedom harvester for rotation is proposed. • The electromechanical coupling model is developed and validated experimentally. • The harvester can generate high voltage at low rotating speeds. • The harvester can harvest vibration energy in multiple frequency bands. - Abstract: Energy can be harvested from rotational motion for powering wireless autonomous electronic devices. The paper presents a magnetically coupled two-degree-of-freedom vibration energy harvester for rotary motion applications. The design consists of two inverted piezoelectric cantilever beams whose free ends point to the rotating shaft. The centrifugal force of the inverted cantilever beam is beneficial to producing large amplitude in a low speed range. The electromechanical coupling dynamical model is developed by the energy method from Hamilton’s principle and validated experimentally. The experimental results indicate that the presented harvester is suitable for low speed rotation and can harvest vibration energy in multiple frequency bands. The first and second resonant behaviors of voltage can be obtained at 420 r/min and 550 r/min, and the average output powers are 564 μW and 535.3 μW, respectively.

  16. A sphericon-shaped magnetic millirobot rolling on a surface actuated by an external wobbling magnetic field

    Directory of Open Access Journals (Sweden)

    Seungmun Jeon

    2017-05-01

    Full Text Available This paper proposes a novel sphericon-shaped magnetic millirobot (SSMM that can roll on a variety of surfaces. The SSMM comprises four identical half cones with a cylindrical magnet inserted into the geometric center. It can roll forward or backward on a surface with repeated rolling cone motions (wobbling motions. Since a rolling SSMM develops its entire surface by means of line contact, a relatively large maximum static friction force can make the SSMM move on a surface steadily and effectively. In this work, a new type of external wobbling magnetic field (EWMF was also derived to manipulate the SSMM’s rolling motions precisely. Then, the controlled rolling motions of prototype SSMMs under various surface conditions were demonstrated to examine the rolling ability of the proposed SSMM.

  17. A simple 5-DoF MR-compatible motion signal measurement system.

    Science.gov (United States)

    Chung, Soon-Cheol; Kim, Hyung-Sik; Yang, Jae-Woong; Lee, Su-Jeong; Choi, Mi-Hyun; Kim, Ji-Hye; Yeon, Hong-Won; Park, Jang-Yeon; Yi, Jeong-Han; Tack, Gye-Rae

    2011-09-01

    The purpose of this study was to develop a simple motion measurement system with magnetic resonance (MR) compatibility and safety. The motion measurement system proposed here can measure 5-DoF motion signals without deteriorating the MR images, and it has no effect on the intense and homogeneous main magnetic field, the temporal-gradient magnetic field (which varies rapidly with time), the transceiver radio frequency (RF) coil, and the RF pulse during MR data acquisition. A three-axis accelerometer and a two-axis gyroscope were used to measure 5-DoF motion signals, and Velcro was used to attach a sensor module to a finger or wrist. To minimize the interference between the MR imaging system and the motion measurement system, nonmagnetic materials were used for all electric circuit components in an MR shield room. To remove the effect of RF pulse, an amplifier, modulation circuit, and power supply were located in a shielded case, which was made of copper and aluminum. The motion signal was modulated to an optic signal using pulse width modulation, and the modulated optic signal was transmitted outside the MR shield room using a high-intensity light-emitting diode and an optic cable. The motion signal was recorded on a PC by demodulating the transmitted optic signal into an electric signal. Various kinematic variables, such as angle, acceleration, velocity, and jerk, can be measured or calculated by using the motion measurement system developed here. This system also enables motion tracking by extracting the position information from the motion signals. It was verified that MR images and motion signals could reliably be measured simultaneously.

  18. Proper motions in the VVV Survey: Results for more than 15 million stars across NGC 6544

    Science.gov (United States)

    Contreras Ramos, R.; Zoccali, M.; Rojas, F.; Rojas-Arriagada, A.; Gárate, M.; Huijse, P.; Gran, F.; Soto, M.; Valcarce, A. A. R.; Estévez, P. A.; Minniti, D.

    2017-12-01

    Context. In the last six years, the VISTA Variable in the Vía Láctea (VVV) survey mapped 562 sq. deg. across the bulge and southern disk of the Galaxy. However, a detailed study of these regions, which includes 36 globular clusters (GCs) and thousands of open clusters is by no means an easy challenge. High differential reddening and severe crowding along the line of sight makes highly hamper to reliably distinguish stars belonging to different populations and/or systems. Aims: The aim of this study is to separate stars that likely belong to the Galactic GC NGC 6544 from its surrounding field by means of proper motion (PM) techniques. Methods: This work was based upon a new astrometric reduction method optimized for images of the VVV survey. Results: PSF-fitting photometry over the six years baseline of the survey allowed us to obtain a mean precision of 0.51 mas yr-1, in each PM coordinate, for stars with Ks< 15 mag. In the area studied here, cluster stars separate very well from field stars, down to the main sequence turnoff and below, allowing us to derive for the first time the absolute PM of NGC 6544. Isochrone fitting on the clean and differential reddening corrected cluster color magnitude diagram yields an age of 11-13 Gyr, and metallicity [Fe/H] =-1.5 dex, in agreement with previous studies restricted to the cluster core. We were able to derive the cluster orbit assuming an axisymmetric model of the Galaxy and conclude that NGC 6544 is likely a halo GC. We have not detected tidal tail signatures associated to the cluster, but a remarkable elongation in the galactic center direction has been found. The precision achieved in the PM determination also allows us to separate bulge stars from foreground disk stars, enabling the kinematical selection of bona fide bulge stars across the whole survey area. Conclusions: Kinematical techniques are a fundamental step toward disentangling different stellar populations that overlap in a studied field. Our results show

  19. Reconstructing the past outburst history of Eta Carinae from WFPC2 proper motions

    Science.gov (United States)

    Smith, Nathan

    2016-10-01

    The HST archive contains multiple epochs of WFPC2 images of the nebula around Eta Carinae taken over a 15-year timespan, although only the earliest few years of data have been analyzed and published. The fact that all these images were taken with the same instrument, with the same pixel sampling and field distortion, makes them an invaluable resource for accurately measuring the expanding ejecta. The goal of a previously accepted AR proposal was to analyze the full set of appropriate continuum-filter HST images to place precise constraints on the avereage ejection date of the Homunculus Nebula; this analysis is now complete (Smith et al 2016) and the nebula appears to have been ejected in the second half of 1847. Here we propose to continue this project by constraining the motion of the more extended and much older Outer Ejecta around Eta Carinae. Older material outside the main bipolar nebula traces previous major outbursts of the star with no recorded historical observations. We propose an ambitious reduction and analysis of the complete WFPC2 imaging dataset of Eta Car. These data can reconstruct its violent mass-loss history over the past thousand years. We have already started this by analyzing two epochs of ACS F658N images, and astonishingly, these data suggested two previous eruptions in the 13th and 15th centuries assuming ballistic motion. WFPC2 images will extend the baseline by 10 yr, and critically, more than 2 epochs allow us to measure any deceleration in the ejecta. We will also analyze Doppler shifts in ground-based spectra in order to reconstruct the 3D geometry of past mass ejection. This AR proposal will fund the final year of a PhD thesis.

  20. Moving magnets in a micromagnetic finite-difference framework

    Science.gov (United States)

    Rissanen, Ilari; Laurson, Lasse

    2018-05-01

    We present a method and an implementation for smooth linear motion in a finite-difference-based micromagnetic simulation code, to be used in simulating magnetic friction and other phenomena involving moving microscale magnets. Our aim is to accurately simulate the magnetization dynamics and relative motion of magnets while retaining high computational speed. To this end, we combine techniques for fast scalar potential calculation and cubic b-spline interpolation, parallelizing them on a graphics processing unit (GPU). The implementation also includes the possibility of explicitly simulating eddy currents in the case of conducting magnets. We test our implementation by providing numerical examples of stick-slip motion of thin films pulled by a spring and the effect of eddy currents on the switching time of magnetic nanocubes.

  1. Study of coupling between neutral-air motion and the ionosphere

    International Nuclear Information System (INIS)

    Bernhardt, P.A.

    1982-06-01

    The coupling between (1) an acoustic wave originating at or below the earth's surface and (2) the ionosphere is described by equations of continuity and motion. The plasma concentration is influenced by collisional and electrostatic forces. Above 130 km altitude, ion-neutral collisions are rare and the plasma tends to be tied to the magnetic field lines. In this region only the magnetic field aligned components of the acoustic disturbance influences the plasma concentration. Below 120 km altitude, ion-neutral collisions dominate over the magnetic field and the plasma responds isotropically to the disturbance. In this lower region, motion of plasma across magnetic field lines produces electric fields and currents. The acoustic wave in the ionosphere may be detected by observations of changes in electron concentration and magnetic field intensity

  2. Classification of particle orbits near the magnetic axis in a tokamak by using constants of motion

    International Nuclear Information System (INIS)

    Satake, Shinsuke; Sugama, Hideo; Okamoto, Masao; Wakatani, Masahiro

    2001-01-01

    A classification of particle orbits near the magnetic axis in a tokamak is presented in a space of constants of motion (COM), which is important to apply Lagrangian formulation of neoclassical transport theory to the region near the axis. Orbit types are distinguished by the number of the turning points of σsub(parallel)=υsub(parallel)/|υsub(parallel)| and σ θ =θ-bar/|θ-bar| on each orbit, where υsub(parallel) is the velocity parallel to the magnetic field, and θ-bar(≡v·∇θ) is the poloidal angular velocity. As a set of COM, (ε, μ, ) is taken, where ε is the energy of a particle, μ is the magnetic moment, and is the bounce-averaged minor radius position of a particle orbit. Compared with a familiar set of COM (υ, ξ s , r s ), where υ is the particle velocity, r s is the minor radius at which an orbit crosses the mid-plane, and ξ s =υsub(parallel)/υ evaluated at the crossing point, the set of COM (ε, μ, ) is more suitable in practice for Lagrangian formulation of neoclassical transport theory, in which the particle diffusion is described by the change of average position of particles by collisions. Near the magnetic axis, it is found that there are overlaps in regions of orbit types in the (ε, μ, ) space and that has a minimum value for a given ε. (author)

  3. Motion-insensitive rapid configuration relaxometry.

    Science.gov (United States)

    Nguyen, Damien; Bieri, Oliver

    2017-08-01

    Triple echo steady state (TESS) uses the lowest steady state configuration modes for rapid relaxometry. Due to its unbalanced gradient scheme, however, TESS is inherently motion-sensitive. The purpose of this work is to merge TESS with a balanced acquisition scheme for motion-insensitive rapid configuration relaxometry, termed MIRACLE. The lowest order steady state free precession (SSFP) configurations are retrieved by Fourier transformation of the frequency response of N frequency-shifted balanced SSFP (bSSFP) scans and subsequently processed for relaxometry, as proposed with TESS. Accuracy of MIRACLE is evaluated from simulations, phantom studies as well as in vivo brain and cartilage imaging at 3T. Simulations and phantom results revealed no conceptual flaw, and artifact-free configuration imaging was achieved in vivo. Overall, relaxometry results were accurate in phantoms and in good agreement for cartilage and for T2 in the brain, but apparent low T1 values were observed for brain white matter; reflecting asymmetries in the bSSFP profile. Rapid T1 and T2 mapping with MIRACLE offers analogous properties as TESS while successfully mitigating its motion-sensitivity. As a result of the Fourier transformation, relaxometry becomes sensitive to the voxel frequency distribution, which may contain useful physiologic information, such as structural brain integrity. © 2016 International Society for Magnetic Resonance in Medicine. Magn Reson Med 78:518-526, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  4. Evaluation of Transient Motion During Gadoxetic Acid-Enhanced Multiphasic Liver Magnetic Resonance Imaging Using Free-Breathing Golden-Angle Radial Sparse Parallel Magnetic Resonance Imaging.

    Science.gov (United States)

    Yoon, Jeong Hee; Lee, Jeong Min; Yu, Mi Hye; Hur, Bo Yun; Grimm, Robert; Block, Kai Tobias; Chandarana, Hersh; Kiefer, Berthold; Son, Yohan

    2018-01-01

    The aims of this study were to observe the pattern of transient motion after gadoxetic acid administration including incidence, onset, and duration, and to evaluate the clinical feasibility of free-breathing gadoxetic acid-enhanced liver magnetic resonance imaging using golden-angle radial sparse parallel (GRASP) imaging with respiratory gating. In this institutional review board-approved prospective study, 59 patients who provided informed consents were analyzed. Free-breathing dynamic T1-weighted images (T1WIs) were obtained using GRASP at 3 T after a standard dose of gadoxetic acid (0.025 mmol/kg) administration at a rate of 1 mL/s, and development of transient motion was monitored, which is defined as a distinctive respiratory frequency alteration of the self-gating MR signals. Early arterial, late arterial, and portal venous phases retrospectively reconstructed with and without respiratory gating and with different temporal resolutions (nongated 13.3-second, gated 13.3-second, gated 6-second T1WI) were evaluated for image quality and motion artifacts. Diagnostic performance in detecting focal liver lesions was compared among the 3 data sets. Transient motion (mean duration, 21.5 ± 13.0 seconds) was observed in 40.0% (23/59) of patients, 73.9% (17/23) of which developed within 15 seconds after gadoxetic acid administration. On late arterial phase, motion artifacts were significantly reduced on gated 13.3-second and 6-second T1WI (3.64 ± 0.34, 3.61 ± 0.36, respectively), compared with nongated 13.3-second T1WI (3.12 ± 0.51, P < 0.0001). Overall, image quality was the highest on gated 13.3-second T1WI (3.76 ± 0.39) followed by gated 6-second and nongated 13.3-second T1WI (3.39 ± 0.55, 2.57 ± 0.57, P < 0.0001). Only gated 6-second T1WI showed significantly higher detection performance than nongated 13.3-second T1WI (figure of merit, 0.69 [0.63-0.76]) vs 0.60 [0.56-0.65], P = 0.004). Transient motion developed in 40% (23/59) of patients shortly after

  5. Magnetosheath density fluctuations and magnetopause motion

    Energy Technology Data Exchange (ETDEWEB)

    Sibeck, D.G. [Johns Hopkins Univ. Applied Physics Lab., Laurel, MD (United States); Gosling, J.T. [Los Alamos National Lab., NM (United States)

    1996-01-01

    The interplanetary magnetic field (IMF) orientation controls foreshock densities and modulates the fraction of the solar wind dynamic pressure applied to the magnetosphere. Such pressure variations produce bow shock and magnetopause motion and cause the radial profiles for various magnetosheath parameters to sweep inward and outward past nearly stationary satellites. The authors report ISEE 2 observations of correlated density and speed fluctuations, and anticorrelated density and temperature fluctuations, on an outbound pass through the northern dawnside magnetosheath. Densities decreased when the magnetic field rotated southward and draped about the magnetopause. In the absence of any significant solar wind density or dynamic pressure variations, they interpret the magnetosheath fluctuations as evidence for radial magnetosheath motion induced by variations in the IMF orientation. 41 refs., 8 figs.

  6. How much motion is too much motion? Determining motion thresholds by sample size for reproducibility in developmental resting-state MRI

    Directory of Open Access Journals (Sweden)

    Julia Leonard

    2017-03-01

    Full Text Available A constant problem developmental neuroimagers face is in-scanner head motion. Children move more than adults and this has led to concerns that developmental changes in resting-state connectivity measures may be artefactual. Furthermore, children are challenging to recruit into studies and therefore researchers have tended to take a permissive stance when setting exclusion criteria on head motion. The literature is not clear regarding our central question: How much motion is too much? Here, we systematically examine the effects of multiple motion exclusion criteria at different sample sizes and age ranges in a large openly available developmental cohort (ABIDE; http://preprocessed-connectomes-project.org/abide. We checked 1 the reliability of resting-state functional magnetic resonance imaging (rs-fMRI pairwise connectivity measures across the brain and 2 the accuracy with which we can separate participants with autism spectrum disorder from typically developing controls based on their rs-fMRI scans using machine learning. We find that reliability on average is primarily sensitive to the number of participants considered, but that increasingly permissive motion thresholds lower case-control prediction accuracy for all sample sizes.

  7. HUBBLE SPACE TELESCOPE PROPER MOTION (HSTPROMO) CATALOGS OF GALACTIC GLOBULAR CLUSTERS. I. SAMPLE SELECTION, DATA REDUCTION, AND NGC 7078 RESULTS

    Energy Technology Data Exchange (ETDEWEB)

    Bellini, A.; Anderson, J.; Van der Marel, R. P.; Watkins, L. L. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); King, I. R. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Bianchini, P. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Chanamé, J. [Instituto de Astrofísica, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Macul 782-0436, Santiago (Chile); Chandar, R. [Department of Physics and Astronomy, The University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606 (United States); Cool, A. M. [Department of Physics and Astronomy, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132 (United States); Ferraro, F. R.; Massari, D. [Dipartimento di Fisica e Astronomia, Università di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Ford, H., E-mail: bellini@stsci.edu [Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)

    2014-12-20

    We present the first study of high-precision internal proper motions (PMs) in a large sample of globular clusters, based on Hubble Space Telescope (HST) data obtained over the past decade with the ACS/WFC, ACS/HRC, and WFC3/UVIS instruments. We determine PMs for over 1.3 million stars in the central regions of 22 clusters, with a median number of ∼60,000 stars per cluster. These PMs have the potential to significantly advance our understanding of the internal kinematics of globular clusters by extending past line-of-sight (LOS) velocity measurements to two- or three-dimensional velocities, lower stellar masses, and larger sample sizes. We describe the reduction pipeline that we developed to derive homogeneous PMs from the very heterogeneous archival data. We demonstrate the quality of the measurements through extensive Monte Carlo simulations. We also discuss the PM errors introduced by various systematic effects and the techniques that we have developed to correct or remove them to the extent possible. We provide in electronic form the catalog for NGC 7078 (M 15), which consists of 77,837 stars in the central 2.'4. We validate the catalog by comparison with existing PM measurements and LOS velocities and use it to study the dependence of the velocity dispersion on radius, stellar magnitude (or mass) along the main sequence, and direction in the plane of the sky (radial or tangential). Subsequent papers in this series will explore a range of applications in globular-cluster science and will also present the PM catalogs for the other sample clusters.

  8. Adiabatic motion of charged dust grains in rotating magnetospheres

    International Nuclear Information System (INIS)

    Northrop, T.G.; Hill, J.R.

    1983-01-01

    Dust grains in the ring systems and rapidly rotating magnetospheres of the outer planets such as Jupiter and Saturn may be sufficiently charged that the magnetic and electric forces on them are comparable with the gravitational force. The adiabatic theory of charged particle motion has previously been applied to electrons and atomic size particles. But it is also applicable to these charged dust grains in the micrometer and smaller size range. We derive here the guiding center equation of motion, drift velocity, and parallel equation of motion for these grains in a rotating magnetosphere. The effects of periodic grain charge-discharge have not been treated previously and have been included in this analysis. Grain charge is affected by the surrounding plasma properties and by the grain plasma velocity (among other factors), both of which may vary over the gyrocircle. The resulting charge-discharge process at the gyrofrequency destroys the invariance of the magnetic moment and causes a grain to move radially. The magnetic moment may increase or decrease, depending on the gyrophase of the charge variation. If it decreases, the motion is always toward synchronous radius for an equatorial grain. But the orbit becomes circular before the grain reaches synchronous radius, a conclusion that follows from an exact constant of the motion. This circularization can be viewed as a consequence of the gradual reduction in the magnetic moment. This circularization also suggests that dust grains leaving Io could not reach the region of the Jovian ring, but several effects could change that conclusion. Excellent qualitative and quantitative agreement is obtained between adiabatic theory and detailed numerical orbit integrations

  9. Helicopter flight simulation motion platform requirements

    Science.gov (United States)

    Schroeder, Jeffery Allyn

    Flight simulators attempt to reproduce in-flight pilot-vehicle behavior on the ground. This reproduction is challenging for helicopter simulators, as the pilot is often inextricably dependent on external cues for pilot-vehicle stabilization. One important simulator cue is platform motion; however, its required fidelity is unknown. To determine the required motion fidelity, several unique experiments were performed. A large displacement motion platform was used that allowed pilots to fly tasks with matched motion and visual cues. Then, the platform motion was modified to give cues varying from full motion to no motion. Several key results were found. First, lateral and vertical translational platform cues had significant effects on fidelity. Their presence improved performance and reduced pilot workload. Second, yaw and roll rotational platform cues were not as important as the translational platform cues. In particular, the yaw rotational motion platform cue did not appear at all useful in improving performance or reducing workload. Third, when the lateral translational platform cue was combined with visual yaw rotational cues, pilots believed the platform was rotating when it was not. Thus, simulator systems can be made more efficient by proper combination of platform and visual cues. Fourth, motion fidelity specifications were revised that now provide simulator users with a better prediction of motion fidelity based upon the frequency responses of their motion control laws. Fifth, vertical platform motion affected pilot estimates of steady-state altitude during altitude repositionings. This refutes the view that pilots estimate altitude and altitude rate in simulation solely from visual cues. Finally, the combined results led to a general method for configuring helicopter motion systems and for developing simulator tasks that more likely represent actual flight. The overall results can serve as a guide to future simulator designers and to today's operators.

  10. Zero-point field in a circular-motion frame

    International Nuclear Information System (INIS)

    Kim, S.K.; Soh, K.S.; Yee, J.H.

    1987-01-01

    The energy spectrum of zero-point fields of a massless scalar field observed by a detector in circular motion is studied by analyzing the Wightman function. It is shown to be quite different from the Planck spectrum which would have been expected from the result of a uniformly accelerated detector. In a nonrelativistic limit zero-point fields with frequencies only up to the first harmonics of the circular-motion frequency contribute dominantly. In an extremely relativistic case the energy spectrum is dominated by a particular pole in the complex proper-time plane

  11. AIRGAP MAGNETIC INDUCTION DISTRIBUTION IN A COAXIALLY-LINEAR SYNCHRONOUS MOTOR WITH AXIAL AND RADIAL DIRECTION OF THE RUNNER PERMANENT MAGNETS MAGNETIZATION

    Directory of Open Access Journals (Sweden)

    Abbasian Mohsen

    2013-02-01

    Full Text Available Results of theoretical and experimental research on magnetic induction distribution in the air gap of a coaxially-linear synchronous motor with reciprocal motion within the pole pitch and axial and radial direction of the permanent magnets magnetization are presented.

  12. Test-electron analysis of the magnetic reconnection topology

    Science.gov (United States)

    Borgogno, D.; Perona, A.; Grasso, D.

    2017-12-01

    Three-dimensional (3D) investigations of the magnetic reconnection field topology in space and laboratory plasmas have identified the abidance of magnetic coherent structures in the stochastic region, which develop during the nonlinear stage of the reconnection process. Further analytical and numerical analyses highlighted the efficacy of some of these structures in limiting the magnetic transport. The question then arises as to what is the possible role played by these patterns in the dynamics of the plasma particles populating the chaotic region. In order to explore this aspect, we provide a detailed description of the nonlinear 3D magnetic field topology in a collisionless magnetic reconnection event with a strong guide field. In parallel, we study the evolution of a population of test electrons in the guiding-center approximation all along the reconnection process. In particular, we focus on the nonlinear spatial redistribution of the initially thermal electrons and show how the electron dynamics in the stochastic region depends on the sign and on the value of their velocities. While the particles with the highest positive speed populate the coherent current structures that survive in the chaotic sea, the presence of the manifolds calculated in the stochastic region defines the confinement area for the electrons with the largest negative velocity. These results stress the link between the magnetic topology and the electron motion and contribute to the overall picture of a non-stationary fluid magnetic reconnection description in a geometry proper to physical systems where the effects of the curvature can be neglected.

  13. Rashba spin–orbit coupling effects on a current-induced domain wall motion

    International Nuclear Information System (INIS)

    Ryu, Jisu; Seo, Soo-Man; Lee, Kyung-Jin; Lee, Hyun-Woo

    2012-01-01

    A current-induced domain wall motion in magnetic nanowires with a strong structural inversion asymmetry [I.M. Miron, T. Moore, H. Szambolics, L.D. Buda-Prejbeanu, S. Auffret, B. Rodmacq, S. Pizzini, J. Vogel, M. Bonfim, A. Schuhl, G. Gaudin, Nat. Mat. 10 (2011) 419] seems to have novel features such as the domain wall motion along the current direction or the delay of the onset of the Walker breakdown. In such a highly asymmetric system, the Rashba spin–orbit coupling (RSOC) may affect a domain wall motion. We studied theoretically the RSOC effects on a domain wall motion and found that the RSOC, indeed, can induce the domain wall motion along the current direction in certain situations. It also delays the Walker breakdown and for a strong RSOC, the Walker breakdown does not occur at all. The RSOC effects are sensitive to the magnetic anisotropy of nanowires and also to the ratio between the Gilbert damping parameter α and the non-adiabaticity parameter β. - Highlights: ► Effects of Rashba spin–orbit coupling on a domain wall motion is calculated. ► The effects depend highly on the anisotropy of a magnetic system. ► It modifies the wall velocity for the system with a perpendicular magnetic anisotropy. ► The modified velocity can be along the current direction in certain situations. ► Rashba spin–orbit coupling also hinders the onset of the Walker breakdown.

  14. Digital anthropomorphic phantoms of non-rigid human respiratory and voluntary body motion for investigating motion correction in emission imaging

    International Nuclear Information System (INIS)

    Könik, Arda; Johnson, Karen L; Dasari, Paul; Pretorius, P H; Dey, Joyoni; King, Michael A; Connolly, Caitlin M; Segars, Paul W; Lindsay, Clifford

    2014-01-01

    The development of methods for correcting patient motion in emission tomography has been receiving increased attention. Often the performance of these methods is evaluated through simulations using digital anthropomorphic phantoms, such as the commonly used extended cardiac torso (XCAT) phantom, which models both respiratory and cardiac motion based on human studies. However, non-rigid body motion, which is frequently seen in clinical studies, is not present in the standard XCAT phantom. In addition, respiratory motion in the standard phantom is limited to a single generic trend. In this work, to obtain a more realistic representation of motion, we developed a series of individual-specific XCAT phantoms, modeling non-rigid respiratory and non-rigid body motions derived from the magnetic resonance imaging (MRI) acquisitions of volunteers. Acquisitions were performed in the sagittal orientation using the Navigator methodology. Baseline (no motion) acquisitions at end-expiration were obtained at the beginning of each imaging session for each volunteer. For the body motion studies, MRI was again acquired only at end-expiration for five body motion poses (shoulder stretch, shoulder twist, lateral bend, side roll, and axial slide). For the respiratory motion studies, an MRI was acquired during free/regular breathing. The magnetic resonance slices were then retrospectively sorted into 14 amplitude-binned respiratory states, end-expiration, end-inspiration, six intermediary states during inspiration, and six during expiration using the recorded Navigator signal. XCAT phantoms were then generated based on these MRI data by interactive alignment of the organ contours of the XCAT with the MRI slices using a graphical user interface. Thus far we have created five body motion and five respiratory motion XCAT phantoms from the MRI acquisitions of six healthy volunteers (three males and three females). Non-rigid motion exhibited by the volunteers was reflected in both respiratory

  15. Digital anthropomorphic phantoms of non-rigid human respiratory and voluntary body motion for investigating motion correction in emission imaging

    Science.gov (United States)

    Könik, Arda; Connolly, Caitlin M.; Johnson, Karen L.; Dasari, Paul; Segars, Paul W.; Pretorius, P. H.; Lindsay, Clifford; Dey, Joyoni; King, Michael A.

    2014-07-01

    The development of methods for correcting patient motion in emission tomography has been receiving increased attention. Often the performance of these methods is evaluated through simulations using digital anthropomorphic phantoms, such as the commonly used extended cardiac torso (XCAT) phantom, which models both respiratory and cardiac motion based on human studies. However, non-rigid body motion, which is frequently seen in clinical studies, is not present in the standard XCAT phantom. In addition, respiratory motion in the standard phantom is limited to a single generic trend. In this work, to obtain a more realistic representation of motion, we developed a series of individual-specific XCAT phantoms, modeling non-rigid respiratory and non-rigid body motions derived from the magnetic resonance imaging (MRI) acquisitions of volunteers. Acquisitions were performed in the sagittal orientation using the Navigator methodology. Baseline (no motion) acquisitions at end-expiration were obtained at the beginning of each imaging session for each volunteer. For the body motion studies, MRI was again acquired only at end-expiration for five body motion poses (shoulder stretch, shoulder twist, lateral bend, side roll, and axial slide). For the respiratory motion studies, an MRI was acquired during free/regular breathing. The magnetic resonance slices were then retrospectively sorted into 14 amplitude-binned respiratory states, end-expiration, end-inspiration, six intermediary states during inspiration, and six during expiration using the recorded Navigator signal. XCAT phantoms were then generated based on these MRI data by interactive alignment of the organ contours of the XCAT with the MRI slices using a graphical user interface. Thus far we have created five body motion and five respiratory motion XCAT phantoms from the MRI acquisitions of six healthy volunteers (three males and three females). Non-rigid motion exhibited by the volunteers was reflected in both respiratory

  16. Motion Artifact in the MR imaging of temporomandibular disorders

    International Nuclear Information System (INIS)

    Tamamura, Kiyoharu; Miyajima, Hisashi; Nihei, Yoshinobu; Nemoto, Ryuichi; Ohno, Tomoya

    1997-01-01

    Recently, magnetic resonance imaging (MRI) is indispensable for the diagnosis of temporomandibular disorders (TMD). Motion Artifacts of MRI occur more frequently than in other conventional methods, because it takes a long time to obtain the images. This paper reported on Motion Artifacts on MRI. MRI studies of 232 temporomandibular joints were performed in 116 patients with TMD by using a 0.5-T magnetic resonance (MR) scanner, with spin echo sequence: protondensity-weighted. And we took MRI slices at opening phase and closing phase. So 232 slices were gathered and we evaluated clinically the incidence of Motion Artifacts, that is to say, double and multiple images and other factors. The 103 slices in 56 patients showed Motion Artifacts. There is no significant difference between sexes. By age group, those in their teens were most frequent, followed by those in their fifties, forties, thirties and twenties. Also the same results were obtained for double image and multiple image. Incidence of Motion Artifact was most frequent at the opening phase. There is no significant difference between double and multiple image. (author)

  17. Is Diaphragm Motion a Good Surrogate for Liver Tumor Motion?

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Juan [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); School of Information Science and Engineering, Shandong University, Jinan, Shandong (China); Cai, Jing [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Wang, Hongjun [School of Information Science and Engineering, Shandong University, Jinan, Shandong (China); Chang, Zheng; Czito, Brian G. [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Bashir, Mustafa R. [Department of Radiology, Duke University Medical Center, Durham, North Carolina (United States); Palta, Manisha [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States); Yin, Fang-Fang, E-mail: fangfang.yin@duke.edu [Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina (United States)

    2014-11-15

    Purpose: To evaluate the relationship between liver tumor motion and diaphragm motion. Methods and Materials: Fourteen patients with hepatocellular carcinoma (10 of 14) or liver metastases (4 of 14) undergoing radiation therapy were included in this study. All patients underwent single-slice cine–magnetic resonance imaging simulations across the center of the tumor in 3 orthogonal planes. Tumor and diaphragm motion trajectories in the superior–inferior (SI), anterior–posterior (AP), and medial–lateral (ML) directions were obtained using an in-house-developed normalized cross-correlation–based tracking technique. Agreement between the tumor and diaphragm motion was assessed by calculating phase difference percentage, intraclass correlation coefficient, and Bland-Altman analysis (Diff). The distance between the tumor and tracked diaphragm area was analyzed to understand its impact on the correlation between the 2 motions. Results: Of all patients, the mean (±standard deviation) phase difference percentage values were 7.1% ± 1.1%, 4.5% ± 0.5%, and 17.5% ± 4.5% in the SI, AP, and ML directions, respectively. The mean intraclass correlation coefficient values were 0.98 ± 0.02, 0.97 ± 0.02, and 0.08 ± 0.06 in the SI, AP, and ML directions, respectively. The mean Diff values were 2.8 ± 1.4 mm, 2.4 ± 1.1 mm, and 2.2 ± 0.5 mm in the SI, AP, and ML directions, respectively. Tumor and diaphragm motions had high concordance when the distance between the tumor and tracked diaphragm area was small. Conclusions: This study showed that liver tumor motion had good correlation with diaphragm motion in the SI and AP directions, indicating diaphragm motion in the SI and AP directions could potentially be used as a reliable surrogate for liver tumor motion.

  18. Magnetic levitation in orbitron system

    International Nuclear Information System (INIS)

    Zub, S.S.

    2014-01-01

    This paper devoted to proof the existence of stable quasi-periodic motions of the magnetic dipole that is under the action of the external magnetic field and homogeneous field of gravity. For proof we used energy-momentum method that is the group-theoretic method of Hamiltonian mechanics. Numerical simulation shows the possibility of realization of stable motions with physically reasonable parameters of the system.

  19. Homothetic and conformal motions in spacelike slices of solutions of Einstein's equations

    International Nuclear Information System (INIS)

    Berger, B.K.

    1976-01-01

    Components of Killing's equation are used to obtain constraints satisfied in a spacelike hypersurface by the intrinsic metric and extrinsic curvature in the presence of a spacetime conformal motion for a solution of Einstein's equations. If the conformal motion is either a homothetic motion or a motion, it is shown that these Killing constraints are preserved by the Einstein evolution equations. It is then shown that the generator of the homothetic motion (homothetic Killing vector) can be constructed if the Killing constraints are satisfied by a set of initial data. It is shown that a homothetic motion in the intrinsic metric is a spacetime homothetic motion if the extrinsic curvature is transformed correctly under the spatial homothetic motion. Further restrictions on a proper conformal motion due to the fact that it is not identically a curvature collineation are obtained. Restrictions on the matter--stress--energy tensor are discussed. Examples are presented

  20. Soliton solutions and chaotic motion of the extended Zakharov-Kuznetsov equations in a magnetized two-ion-temperature dusty plasma

    Energy Technology Data Exchange (ETDEWEB)

    Zhen, Hui-Ling; Tian, Bo, E-mail: tian-bupt@163.com; Wang, Yu-Feng; Sun, Wen-Rong; Liu, Li-Cai [State Key Laboratory of Information Photonics and Optical Communications, and School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China)

    2014-07-15

    The extended Zakharov-Kuznetsov (eZK) equation for the magnetized two-ion-temperature dusty plasma is studied in this paper. With the help of Hirota method, bilinear forms and N-soliton solutions are given, and soliton propagation is graphically analyzed. We find that the soliton amplitude is positively related to the nonlinear coefficient A, while inversely related to the dispersion coefficients B and C. We obtain that the soliton amplitude will increase with the mass of the jth dust grain and the average charge number residing on the dust grain decreased, but the soliton amplitude will increase with the equilibrium number density of the jth dust grain increased. Upon the introduction of the periodic external forcing term, both the weak and developed chaotic motions can occur. Difference between the two chaotic motions roots in the inequality between the nonlinear coefficient l{sub 2} and perturbed term h{sub 1}. The developed chaos can be weakened with B or C decreased and A increased. Periodic motion of the perturbed eZK equation can be observed when there is a balance between l{sub 2} and h{sub 1}.

  1. Motional spin relaxation in photoexcited triplet states

    International Nuclear Information System (INIS)

    Harryvan, D.; Faassen, E. van

    1997-01-01

    Transient EPR experiments were performed on photoexcited spin triplet states of the luminescent dye EOSIN-Y in diluted (order of 1 nMol) frozen propane-1-ol solutions at various temperatures. Photoexcitation was achieved by irradiation with intense, short laser pulses. The details of the spin relaxation, in particular the dependence on time, magnetic field and microwave field strength are all reproduced by a model which computes the total magnetization in a population of photoexcited triplet states undergoing random reorientational motion. Using this model, we estimated the motional correlation times to be around a microsecond. This timescale is two orders of magnitude slower than the phase memory time of the triplets. (author)

  2. Analysing Harmonic Motions with an iPhone's Magnetometer

    Science.gov (United States)

    Yavuz, Ahmet; Temiz, Burak Kagan

    2016-01-01

    In this paper, we propose an experiment for analysing harmonic motion using an iPhone's (or iPad's) magnetometer. This experiment consists of the detection of magnetic field variations obtained from an iPhone's magnetometer sensor. A graph of harmonic motion is directly displayed on the iPhone's screen using the "Sensor Kinetics"…

  3. Streaming flows produced by oscillating interface of magnetic fluid adsorbed on a permanent magnet in alternating magnetic field

    Science.gov (United States)

    Sudo, S.; Ito, M.; Ishimoto, Y.; Nix, S.

    2017-04-01

    This paper describes microstreaming flows generated by oscillating interface of magnetic fluid adsorbed on a circular cylindrical permanent magnet in alternating magnetic field. The interface of magnetic fluid adsorbed on the NdFeB magnet responds to the external alternating magnetic flied as harmonic oscillation. The directions of alternating magnetic field are parallel and antiparallel to the magnetic field of permanent magnet. The oscillation of magnetic fluid interface generates streaming flow around the magnet-magnetic fluid element in water. Microstreaming flows are observed with a high-speed video camera analysis system. The flow pattern generated by magnetic fluid motion depends on the Keulegan-Carpenter number and the Reynolds number.

  4. Nonadiabatic particle motion in magnetic mirror traps

    International Nuclear Information System (INIS)

    Irie, H.; Otsuka, S.; Varma, R.K.; Watanabe, T.; Nishikawa, Kyoji.

    1982-01-01

    By numerical integration of the equation of single particle motion, the basic features of the actual nonadiabatic escape of particles are studied. The results are compared with the predictions of two existing theoretical models: ''diffusion'' model derived by B. V. Chirikov and ''tunneling'' model introduced by R. K. Varma. (author)

  5. Motions and magnetic fields in the solar atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Krat, V A [AN SSSR, Leningrad. Glavnaya Astronomicheskaya Observatoriya

    1977-09-01

    The measured magnetic fields generally cannot be regarded as ''mean'' values of the magnetic field intensity H due to depolarization effects in the sum of the Zeeman components of small elements. A picture of smallest magnetic elements in the photosphere can be identified with the photospheric network of the granulation. A relatively long lifetime of the elements of this network and characteristics of its evolution show that a magnetic field of H > or approximately = 10/sup 2/ Oe is concentrated in the dark network between granules near to the solar disc center. Direct measurements of H in solar prominences give values of H ranging from 10 to 10/sup 2/ Oe. At their boundary they cannot be smaller than 10/sup 2/ Oe. The chromospheric elements seen in the center of H/sub a/ (spectrograms obtained on the solar stratospheric observatory (SSO) in 1970-1973) are about four times wider than photospheric elements. The growth in size of the structure elements from the photosphere to the chromosphere results from the magnetic expansion of elements floating up in the atmosphere. On the basis of the stratospheric and best filter observations it is shown that typical configurations of the field are magnetic arcs. Sunspots are considered as stationary processes dissipating due to magnetohydrodynamic instabilities. They have (observations on the SSO) considerable regions of a homogeneous magnetic field inside the umbra. The complicated system of twisted magnetic ropes in outer parts of the umbra and penumbra results from the dissipation of the main configuration. The most plausible model of a sunspot seems to be a twisted toroid with a steady magnetic field directed along the axis of symmetry inside the toroid. This model explains the fact of appearance of a secondary sunspot group inside the primary main group. The axis of the sunspot toroid always remains in the photosphere. Some properties of ''super-granules'' and ''giant granules'' are discussed.

  6. Stochastic diffusion of dust grains by the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Hassan, M.H.A.; Wallis, M.K.

    1983-10-01

    The effects of the sectored Interplanetary Magnetic Field on charged dust grains orbiting around the sun under radiation pressure and Poynting-Robertson drag forces are examined for initially circular and non-inclined orbits. The distribution function of the charged grains satisfies a Fokker-Planck equation in which the sectored field is taken as a source of stochastic impulses. By adopting the integrals of the impulse-free motion as variable parameters, the Fokker-Planck equation can be properly treated as a diffusion equation. Analytic solutions of the resulting diffusion equation show that dust grains injected near the ecliptic plane are scattered strongly to high helio-latitudes. The scattering is more pronounced for small grains injected at large distances from the Sun. (author)

  7. Electronic motion in the pre-oscillation phase of a smooth bore magnetron

    International Nuclear Information System (INIS)

    Garelis, E.; Hickman, R.B.

    1979-01-01

    The calculation of the electronic motion in the pre-oscillation phase of a smooth bore magnetron is the problem of calculating the electronic motion in the region between two concentric cylinders with an applied radial electric field and a constant axial B/sub z/ magnetic field. The inner cylinder represents the electron emitting cathode and the outer cylinder represents the anode. The emission is assumed to be space charge limited. This results in an electronic cloud surrounding the cathode. The radial velocity of the electrons is limited by the space charge and in addition the axial magnetic field tends to curve the path of the electrons so that they return to the cathode. Consequently, the electronic orbit extends to some distance r 0 from the cathode and for values of the radius r > r 0 exists a charge free region. The model assumes relativistic electronic motion with self-consistent magnetic fields. The magnetic flux is assumed to be conserved; i.e., conducting cylindrical walls

  8. Correlation of photon beam motion with vacuum chamber cooling on the NSLS x-ray ring

    International Nuclear Information System (INIS)

    Johnson, E.D.; Fauchet, A.M.; Zhang, Xiaohao.

    1991-01-01

    The NSLS X-ray ring exhibits a direct correlation between photon beam motion, and distortion of the ring vacuum chamber induced by fluctuations in the cooling system. We have made long term measurements of photon beam vertical position, accelerator vacuum chamber motion, process water temperatures, and angular motions of the magnets around one superperiod of the NSLS x-ray ring. Short term transients in water temperature cause deflection of the ring vacuum chamber which have in turn been shown to induce very small angular rotations of the magnets, on the order of 10 micro-radians. A larger and more difficult to correct effect is the drift in beam position over the course of a fill. This problem has been shown to be related to the thermal gradients that develop across the vacuum chamber which, as a consequence of the configuration of the chamber cooling, depend upon stored current. Orbit simulations based upon the measured rotations are in agreement with the observed beam motions, and reveal that certain patterns of correlated motions of the magnets can produce much larger errors than random motion or concerted motion of all the magnets. During the course of these measurements global orbit feedback was installed, and found to significantly reduce the orbit errors which could not be corrected at their source

  9. Feeling-of-knowing for proper names.

    Science.gov (United States)

    Izaute, Marie; Chambres, Patrick; Larochelle, Serge

    2002-12-01

    The main objective of the presented study was to study feeling-of-knowing (FOK) in proper name retrieval. Many studies show that FOK can predict performance on a subsequent criterion test. Although feeling-of-knowing studies involve questions about proper names, none make this distinction between proper names and common names. Nevertheless, the specific character of proper names as a unique label referring to a person should allow participants to target precisely the desired verbal label. Our idea here was that the unique character of proper name information should result in more accurate FOK evaluations. In the experiment, participants evaluated feeling-of-knowing for proper and common name descriptions. The study demonstrates that FOK judgments are more accurate for proper names than for common names. The implications of the findings for proper names are briefly discussed in terms of feeling-of-knowing hypotheses.

  10. Impact of nucleic acid self-alignment in a strong magnetic field on the interpretation of indirect spin–spin interactions

    International Nuclear Information System (INIS)

    Vavřinská, Andrea; Zelinka, Jiří; Šebera, Jakub; Sychrovský, Vladimír; Fiala, Radovan; Boelens, Rolf; Sklenář, Vladimír; Trantírek, Lukáš

    2016-01-01

    Heteronuclear and homonuclear direct (D) and indirect (J) spin–spin interactions are important sources of structural information about nucleic acids (NAs). The Hamiltonians for the D and J interactions have the same functional form; thus, the experimentally measured apparent spin–spin coupling constant corresponds to a sum of J and D. In biomolecular NMR studies, it is commonly presumed that the dipolar contributions to Js are effectively canceled due to random molecular tumbling. However, in strong magnetic fields, such as those employed for NMR analysis, the tumbling of NA fragments is anisotropic because the inherent magnetic susceptibility of NAs causes an interaction with the external magnetic field. This motional anisotropy is responsible for non-zero D contributions to Js. Here, we calculated the field-induced D contributions to 33 structurally relevant scalar coupling constants as a function of magnetic field strength, temperature and NA fragment size. We identified two classes of Js, namely 1 J CH and 3 J HH couplings, whose quantitative interpretation is notably biased by NA motional anisotropy. For these couplings, the magnetic field-induced dipolar contributions were found to exceed the typical experimental error in J-coupling determinations by a factor of two or more and to produce considerable over- or under-estimations of the J coupling-related torsion angles, especially at magnetic field strengths >12 T and for NA fragments longer than 12 bp. We show that if the non-zero D contributions to J are not properly accounted for, they might cause structural artifacts/bias in NA studies that use solution NMR spectroscopy

  11. Metachronal Motion of Artificial Magnetic Cilia

    Science.gov (United States)

    Hanasoge, Srinivas; Hesketh, Peter; Alexeev, Alexander

    2017-11-01

    Most microorganisms use asymmetrically oscillating hair like cilia on their surface to achieve fluid transport. These cilia are often seen to beat in a metachronal fashion with a constant phase difference with the neighbors which generates a travelling wave. Although the origin of metachronal waves in such cilia is not well understood, mimicking such behavior in synthetic systems could prove useful in achieving similar advantages. In this work, we demonstrate metachronal waves in synthetic magnetic ciliary systems. The soft magnetic cilia are forced by a uniform rotating magnetic field. The cilia bend as the field rotates and tend to align along the direction of field to minimize the potential energy. Longer cilia bend to a larger degree, while the shorter cilia show less bending. This difference in the bending of cilia based on their length leads to a phase difference in their oscillation cycle. We exploit this phase differences to metachronally oscillate the synthetic cilia. We fabricate an array consisting of cilia with increasing lengths, in which the cilia beat with a constant phase difference with the neighboring cilia, producing a travelling wave. Such behavior could potentially be useful in enhanced fluid and particle transport as seen in natural systems. USDA.

  12. Mechanism of magnetic liquid flowing in the magnetic liquid seal gap of reciprocating shaft

    Science.gov (United States)

    Li, Decai; Xu, Haiping; He, Xinzhi; Lan, Huiqing

    2005-03-01

    In order to solve the problems that exist in the magnetic liquid seal of reciprocating shaft, we have set up an experimental facility, which composes a camera, microscope, step-by-step motor, pin roller screw, reciprocating motion shaft, pole pieces, permanent magnet and the magnetic liquid in the seal gap. Through the optical technology and image process of the experimental facility, we have studied the magnetic liquid flow in the seal gap when the reciprocating shaft moves with different velocities and strokes. This study specially concentrates on: (1) the regular pattern of such flow; (2) the loss quantity of magnetic liquid caused by the reciprocating motion shaft; (3) the failure reasons of this magnetic liquid seal; and (4) the design of a new structure for the magnetic liquid seal of reciprocating shaft. The application indicates that the new structure is very effective in some occasions. The new structure was accepted as the state patent in 2001 and authenticated as the achievement in the scientific research in 2002.

  13. Mechanism of magnetic liquid flowing in the magnetic liquid seal gap of reciprocating shaft

    International Nuclear Information System (INIS)

    Li Decai; Xu Haiping; He Xinzhi; Lan Huiqing

    2005-01-01

    In order to solve the problems that exist in the magnetic liquid seal of reciprocating shaft, we have set up an experimental facility, which composes a camera, microscope, step-by-step motor, pin roller screw, reciprocating motion shaft, pole pieces, permanent magnet and the magnetic liquid in the seal gap. Through the optical technology and image process of the experimental facility, we have studied the magnetic liquid flow in the seal gap when the reciprocating shaft moves with different velocities and strokes. This study specially concentrates on: (1) the regular pattern of such flow; (2) the loss quantity of magnetic liquid caused by the reciprocating motion shaft; (3) the failure reasons of this magnetic liquid seal; and (4) the design of a new structure for the magnetic liquid seal of reciprocating shaft. The application indicates that the new structure is very effective in some occasions. The new structure was accepted as the state patent in 2001 and authenticated as the achievement in the scientific research in 2002

  14. Comparison of Nonlinear Model Results Using Modified Recorded and Synthetic Ground Motions

    International Nuclear Information System (INIS)

    Spears, Robert E.; Wilkins, J. Kevin

    2011-01-01

    A study has been performed that compares results of nonlinear model runs using two sets of earthquake ground motion time histories that have been modified to fit the same design response spectra. The time histories include applicable modified recorded earthquake ground motion time histories and synthetic ground motion time histories. The modified recorded earthquake ground motion time histories are modified from time history records that are selected based on consistent magnitude and distance. The synthetic ground motion time histories are generated using appropriate Fourier amplitude spectrums, Arias intensity, and drift correction. All of the time history modification is performed using the same algorithm to fit the design response spectra. The study provides data to demonstrate that properly managed synthetic ground motion time histories are reasonable for use in nonlinear seismic analysis.

  15. An analogy of a magnetic mirror in mechanics

    International Nuclear Information System (INIS)

    Lal, Amit; Badiger, Shrikrishna M

    2005-01-01

    The motion of a charged particle in a magnetic mirror device is compared to the motion of a bead spiralling into a smooth hollow cone. The complete solution of the motion of the bead is derived and physical aspects of the solution obtained are discussed. Similarities between the motion of the bead and that of a charged particle in a magnetic mirror device are pointed out. The effort is primarily aimed at enhancing the physical understanding of the mechanics of a charged particle in a magnetic mirror device and secondarily at proposing an equivalent mechanics problem, devoid of any electro-dynamical aspect but still possessing all the interesting features of the original problem. The proposed problem can be taught at upper-division undergraduate level

  16. The CMS Experiment: on and under Ground Motions of Structures Due to the Magnetic Field Forces as Observed by the Link Alignment System

    International Nuclear Information System (INIS)

    Alberdi, J.; Arce, J.; Barcala, J. M.; Calvo, E.; Ferrando, A.; Josa, M. I.; Molinero, A.; Navarrete, J.; Oller, J. C.; Yuste, C.; Brochero, J.; Calderon, A.; Fernandez, M. G.; Gomez, G.; Gonzalez-Sanchez, F. J.; Martinez-Ribero, C.; Matorras, F.; Rodrigo, T.; Rui-Arbol, P.; Scodellaro, L.; Sobron, M.; Vila, I.; Virto, A. L.; Fernandez, J.

    2010-01-01

    This document describes results obtained from the Link Alignment System data recorded during the CMS Magnet Test (at SX5 on ground Hall) and the CRAFT08 and 09 periods data taking in the point P5 (UX5), 100 m underground. A brief description of the system is followed by the discussion of the detected relative displacements (from micrometres to centimetres) between detector elements and rotation of detector structures (from microradiants to milliradiants). Observed motions are studied as functions of the magnetic fi eld intensity. Comparisons between recorded data on and under ground are made. (Author) 23 refs.

  17. The CMS Experiment: on and under Ground Motions of Structures Due to the Magnetic Field Forces as Observed by the Link Alignment System

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, J.; Arce, J.; Barcala, J. M.; Calvo, E.; Ferrando, A.; Josa, M. I.; Molinero, A.; Navarrete, J.; Oller, J. C.; Yuste, C.; Brochero, J.; Calderon, A.; Fernandez, M. G.; Gomez, G.; Gonzalez-Sanchez, F. J.; Martinez-Ribero, C.; Matorras, F.; Rodrigo, T.; Rui-Arbol, P.; Scodellaro, L.; Sobron, M.; Vila, I.; Virto, A. L.; Fernandez, J.

    2010-05-01

    This document describes results obtained from the Link Alignment System data recorded during the CMS Magnet Test (at SX5 on ground Hall) and the CRAFT08 and 09 periods data taking in the point P5 (UX5), 100 m underground. A brief description of the system is followed by the discussion of the detected relative displacements (from micrometres to centimetres) between detector elements and rotation of detector structures (from microradiants to milliradiants). Observed motions are studied as functions of the magnetic fi eld intensity. Comparisons between recorded data on and under ground are made. (Author) 23 refs.

  18. Self-assembly of robotic micro- and nanoswimmers using magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Cheang, U. Kei; Kim, Min Jun, E-mail: mkim@coe.drexel.edu [Drexel University, Department of Mechanical Engineering & Mechanics (United States)

    2015-03-15

    Micro- and nanoscale robotic swimmers are very promising to significantly enhance the performance of particulate drug delivery by providing high accuracy at extremely small scales. Here, we introduce micro- and nanoswimmers fabricated using self-assembly of nanoparticles and control via magnetic fields. Nanoparticles self-align into parallel chains under magnetization. The swimmers exhibit flexibility under a rotating magnetic field resulting in chiral structures upon deformation, thereby having the prerequisite for non-reciprocal motion to move about at low Reynolds number. The swimmers are actuated wirelessly using an external rotating magnetic field supplied by approximate Helmholtz coils. By controlling the concentration of the suspended magnetic nanoparticles, the swimmers can be modulated into different sizes. Nanoscale swimmers are largely influenced by Brownian motion, as observed from their jerky trajectories. The microswimmers, which are roughly three times larger, are less vulnerable to the effects from Brownian motion. In this paper, we demonstrate responsive directional control of micro- and nanoswimmers and compare their respective diffusivities and trajectories to characterize the implications of Brownian disturbance on the motions of small and large swimmers. We then performed a simulation using a kinematic model for the magnetic swimmers including the stochastic nature of Brownian motion.

  19. Self-assembly of robotic micro- and nanoswimmers using magnetic nanoparticles

    Science.gov (United States)

    Cheang, U. Kei; Kim, Min Jun

    2015-03-01

    Micro- and nanoscale robotic swimmers are very promising to significantly enhance the performance of particulate drug delivery by providing high accuracy at extremely small scales. Here, we introduce micro- and nanoswimmers fabricated using self-assembly of nanoparticles and control via magnetic fields. Nanoparticles self-align into parallel chains under magnetization. The swimmers exhibit flexibility under a rotating magnetic field resulting in chiral structures upon deformation, thereby having the prerequisite for non-reciprocal motion to move about at low Reynolds number. The swimmers are actuated wirelessly using an external rotating magnetic field supplied by approximate Helmholtz coils. By controlling the concentration of the suspended magnetic nanoparticles, the swimmers can be modulated into different sizes. Nanoscale swimmers are largely influenced by Brownian motion, as observed from their jerky trajectories. The microswimmers, which are roughly three times larger, are less vulnerable to the effects from Brownian motion. In this paper, we demonstrate responsive directional control of micro- and nanoswimmers and compare their respective diffusivities and trajectories to characterize the implications of Brownian disturbance on the motions of small and large swimmers. We then performed a simulation using a kinematic model for the magnetic swimmers including the stochastic nature of Brownian motion.

  20. Self-assembly of robotic micro- and nanoswimmers using magnetic nanoparticles

    International Nuclear Information System (INIS)

    Cheang, U. Kei; Kim, Min Jun

    2015-01-01

    Micro- and nanoscale robotic swimmers are very promising to significantly enhance the performance of particulate drug delivery by providing high accuracy at extremely small scales. Here, we introduce micro- and nanoswimmers fabricated using self-assembly of nanoparticles and control via magnetic fields. Nanoparticles self-align into parallel chains under magnetization. The swimmers exhibit flexibility under a rotating magnetic field resulting in chiral structures upon deformation, thereby having the prerequisite for non-reciprocal motion to move about at low Reynolds number. The swimmers are actuated wirelessly using an external rotating magnetic field supplied by approximate Helmholtz coils. By controlling the concentration of the suspended magnetic nanoparticles, the swimmers can be modulated into different sizes. Nanoscale swimmers are largely influenced by Brownian motion, as observed from their jerky trajectories. The microswimmers, which are roughly three times larger, are less vulnerable to the effects from Brownian motion. In this paper, we demonstrate responsive directional control of micro- and nanoswimmers and compare their respective diffusivities and trajectories to characterize the implications of Brownian disturbance on the motions of small and large swimmers. We then performed a simulation using a kinematic model for the magnetic swimmers including the stochastic nature of Brownian motion

  1. Nuclear magnetic resonance and relaxation studies of the structure and segmental motions of 4-vinyl-pyridinic polymers in solution

    International Nuclear Information System (INIS)

    Ghesquiere, Denis

    1978-01-01

    The poly 4-vinylpyridine, its quaternized products from HBr and n-alkyl-bromides, and its N-oxide form have been investigated by nuclear magnetic resonance of proton at 100 and 250 MHz and carbon-13 at 25.15 MHz, The 1 H and 13 C relaxation data of poly-vinylpyridine and its ionized form have been correlated with conformational calculations. They have been interpreted in terms of an isotropic motion of the macromolecular segments introducing a correlation times distribution and of an oscillation motion of the pyridyl groups. The same treatment have been used for the 13 C relaxation data of the poly 4- vinyl-pyridines quaternized at various rates by n-alkyl-bromides. The 13 C relaxation times in the side-chains have been interpreted first by semi-empirical equations assuming an exponential gradient of the diffusion coefficients along them, and also by a Monte Carlo simulation of the motions. The results have shown that the quaternization induces a strong rigidity of the macromolecular backbone and that the dominant effect is the electrostatic interactions. On the other hand it seems that the motion of pyridyl rings is not affected. Moreover we have found a range of oscillation amplitudes in agreement with conformational energy calculations and the results obtained from a conformational study of the poly 4-vinylpyridine N-oxide by 1 H and 13 C NMR contact shifts induced by Ni II paramagnetic ions. (author) [fr

  2. Nonlinear dynamic behaviour of a rotor-foundation system coupled through passive magnetic bearings with magnetic anisotropy - Theory and experiment

    DEFF Research Database (Denmark)

    Enemark, Søren; Santos, Ilmar F.

    2016-01-01

    In this work, the nonlinear dynamic behaviour of a vertical rigid rotor interacting with a flexible foundation by means of two passive magnetic bearings is quantified and evaluated. The quantification is based on theoretical and experimental investigation of the non-uniformity (anisotropy......) of the magnetic field and the weak nonlinearity of the magnetic forces. Through mathematical modelling the nonlinear equations of motion are established for describing the shaft and bearing housing lateral dynamics coupled via the nonlinear and non-uniform magnetic forces. The equations of motion are solved...

  3. Analytical solutions for the motion of a charged particle in electric and magnetic fields via non-singular fractional derivatives

    Science.gov (United States)

    Morales-Delgado, V. F.; Gómez-Aguilar, J. F.; Taneco-Hernandez, M. A.

    2017-12-01

    In this work we propose fractional differential equations for the motion of a charged particle in electric, magnetic and electromagnetic fields. Exact solutions are obtained for the fractional differential equations by employing the Laplace transform method. The temporal fractional differential equations are considered in the Caputo-Fabrizio-Caputo and Atangana-Baleanu-Caputo sense. Application examples consider constant, ramp and harmonic fields. In addition, we present numerical results for different values of the fractional order. In all cases, when α = 1, we recover the standard electrodynamics.

  4. Noncontrast magnetic resonance angiography of the hand: improved arterial conspicuity by multidirectional flow-sensitive dephasing magnetization preparation in 3D balanced steady-state free precession imaging.

    Science.gov (United States)

    Fan, Zhaoyang; Hodnett, Philip A; Davarpanah, Amir H; Scanlon, Timothy G; Sheehan, John J; Varga, John; Carr, James C; Li, Debiao

    2011-08-01

    : To develop a flow-sensitive dephasing (FSD) preparative scheme to facilitate multidirectional flow-signal suppression in 3-dimensional balanced steady-state free precession imaging and to validate the feasibility of the refined sequence for noncontrast magnetic resonance angiography (NC-MRA) of the hand. : A new FSD preparative scheme was developed that combines 2 conventional FSD modules. Studies using a flow phantom (gadolinium-doped water 15 cm/s) and the hands of 11 healthy volunteers (6 males and 5 females) were performed to compare the proposed FSD scheme with its conventional counterpart with respect to the signal suppression of multidirectional flow. In 9 of the 11 healthy subjects and 2 patients with suspected vasculitis and documented Raynaud phenomenon, respectively, 3-dimensional balanced steady-state free precession imaging coupled with the new FSD scheme was compared with spatial-resolution-matched (0.94 × 0.94 × 0.94 mm) contrast-enhanced magnetic resonance angiography (0.15 mmol/kg gadopentetate dimeglumine) in terms of overall image quality, venous contamination, motion degradation, and arterial conspicuity. : The proposed FSD scheme was able to suppress 2-dimensional flow signal in the flow phantom and hands and yielded significantly higher arterial conspicuity scores than the conventional scheme did on NC-MRA at the regions of common digitals and proper digitals. Compared with contrast-enhanced magnetic resonance angiography, the refined NC-MRA technique yielded comparable overall image quality and motion degradation, significantly less venous contamination, and significantly higher arterial conspicuity score at digital arteries. : The FSD-based NC-MRA technique is improved in the depiction of multidirectional flow by applying a 2-module FSD preparation, which enhances its potential to serve as an alternative magnetic resonance angiography technique for the assessment of hand vascular abnormalities.

  5. Simultaneous PET-MR acquisition and MR-derived motion fields for correction of non-rigid motion in PET

    International Nuclear Information System (INIS)

    Tsoumpas, C.; Mackewn, J.E.; Halsted, P.; King, A.P.; Buerger, C.; Totman, J.J.; Schaeffter, T.; Marsden, P.K.

    2010-01-01

    Positron emission tomography (PET) provides an accurate measurement of radiotracer concentration in vivo, but performance can be limited by subject motion which degrades spatial resolution and quantitative accuracy. This effect may become a limiting factor for PET studies in the body as PET scanner technology improves. In this work, we propose a new approach to address this problem by employing motion information from images measured simultaneously using a magnetic resonance (MR) scanner. The approach is demonstrated using an MR-compatible PET scanner and PET-MR acquisition with a purpose-designed phantom capable of non-rigid deformations. Measured, simultaneously acquired MR data were used to correct for motion in PET, and results were compared with those obtained using motion information from PET images alone. Motion artefacts were significantly reduced and the PET image quality and quantification was significantly improved by the use of MR motion fields, whilst the use of PET-only motion information was less successful. Combined PET-MR acquisitions potentially allow PET motion compensation in whole-body acquisitions without prolonging PET acquisition time or increasing radiation dose. This, to the best of our knowledge, is the first study to demonstrate that simultaneously acquired MR data can be used to estimate and correct for the effects of non-rigid motion in PET. (author)

  6. Direct excitation of resonant torsional Alfven waves by footpoint motions

    NARCIS (Netherlands)

    Ruderman, M. S.; Berghmans, D.; Goossens, M.; Poedts, S.

    1997-01-01

    The present paper studies the heating of coronal loops by linear resonant Alfven waves that are excited by the motions of the photospheric footpoints of the magnetic field lines. The analysis is restricted to torsionally polarised footpoint motions in an axially symmetric system so that only

  7. Magnetic Nano- and Micro- Particles in Living Cells: Kinetics and Fluctuations

    Science.gov (United States)

    Pease, C.; Chiang, N.; Pierce, C.; Muthusamy, N.; Sooryakumar, R.

    2015-03-01

    Functional nano and micro materials have recently been used not only as diagnostic tools for extracellular studies but also as intracellular drug delivery vehicles and as internal probes of the cell. To realize proper cellular applications, it is important not only to achieve efficient delivery of these materials to targeted cells, but also to control their movement and activity within the confines of the cell. In this presentation, superparamagnetic nano and micro particles are utilized as probes, with their responses to weak external magnetic fields enabling them to be maneuvered within a cell. In order to generate the required local magnetic fields needed for manipulation, the fields emanating from microscopic domain walls stabilized on patterned surface profiles are used in conjunction with weak external magnetic fields to create mobile traps that can localize and transport the internalized particle. Preliminary findings on creating the mobile traps suitable for applications to probe the interior of cells, and the responses, both Brownian fluctuations and directed motion, of particles ranging in size from 200 nm to 1 micron within HS-5 cells will be presented. Future applications to probe cellular behavior within the framework of emerging biomaterials will be discussed.

  8. Flow-synchronous field motion refrigeration

    Science.gov (United States)

    Hassen, Charles N.

    2017-08-22

    An improved method to manage the flow of heat in an active regenerator in a magnetocaloric or an electrocaloric heat-pump refrigeration system, in which heat exchange fluid moves synchronously with the motion of a magnetic or electric field. Only a portion of the length of the active regenerator bed is introduced to or removed from the field at one time, and the heat exchange fluid flows from the cold side toward the hot side while the magnetic or electric field moves along the active regenerator bed.

  9. Passive magnetic bearing systems stabilizer/bearing utilizing time-averaging of a periodic magnetic field

    Science.gov (United States)

    Post, Richard F.

    2017-10-03

    A high-stiffness stabilizer/bearings for passive magnetic bearing systems is provide where the key to its operation resides in the fact that when the frequency of variation of the repelling forces of the periodic magnet array is large compared to the reciprocal of the growth time of the unstable motion, the rotating system will feel only the time-averaged value of the force. When the time-averaged value of the force is radially repelling by the choice of the geometry of the periodic magnet array, the Earnshaw-related unstable hit motion that would occur at zero rotational speed is suppressed when the system is rotating at operating speeds.

  10. Magneto-optical study of domain wall dynamics and giant Barkhausen jump in magnetic microwires

    International Nuclear Information System (INIS)

    Chizhik, A.; Zhukov, A.; Blanco, J.M.; Gonzalez, J.

    2012-01-01

    Investigation of surface domain walls motion in Co-rich magnetic microwires has been performed in circular and axial magnetic fields. The dc axial magnetic field acceleration of the domain wall motion related to the influence of the axial field on the structure of the moving domain wall has been discovered. Pulsed axial magnetic field induced unidirectional motion of surface domain wall also has been found.

  11. Analytical guide wire motion algorithm for simulation of endovascular interventions

    NARCIS (Netherlands)

    Konings, M. K.; van de Kraats, E. B.; Alderliesten, T.; Niessen, W. J.

    2003-01-01

    Performing minimally invasive vascular interventions requires proper training, as a guide wire needs to be manipulated, by the tail, under fluoroscopic guidance. To provide a training environment, the motion of the guide wire inside the human vasculature can be simulated by computer. Such a

  12. Extensions of guiding center motion to higher order

    International Nuclear Information System (INIS)

    Northrop, T.G.; Rome, J.A.

    1978-01-01

    In a static magnetic field, some well-known guiding center equations maintain their form when extended to next order in gyroradius. In these cases, it is only necessary to include the next order term in the magnetic moment series. The differential equation for guiding center motion which describes both the parallel and perpendicular velocities correctly through first order in gyroradius is given. The question of how to define the guiding center position through second order arises and is discussed, and second order drifts are derived for one usual definition. The toroidal canonical angular momentum, P/sub phi/, of the guiding center in an axisymmetric field is shown to be conserved using the guiding center velocity correct through first order. When second-order motion is included, P/sub phi/ is no longer a constant. The above extensions of guiding center theory help to resolve the different tokamak orbits obtained either by using the guiding center equations of motion or by using conservation of P/sub phi/

  13. Extensions of guiding center motion to higher order

    International Nuclear Information System (INIS)

    Northrop, T.G.; Rome, J.A.

    1977-07-01

    In a static magnetic field, some well-known guiding center equations maintain their form when extended to next order in gyroradius. In these cases, it is only necessary to include the next order term in the magnetic moment series. The differential equation for guiding center motion which describes both the parallel and perpendicular velocities correctly through first order in gyroradius is given. The question of how to define the guiding center position through second order arises and is discussed, and second order drifts are derived for one usual definition. The toroidal canonical angular momentum, P/sub phi/, of the guiding center in an axisymmetric field is shown to be conserved using the guiding center velocity correct through first order. When second order motion is included, P/sub phi/ is no longer a constant. The above extensions of guiding center theory help to resolve the different tokamak orbits obtained either by using the guiding center equations of motion or by using conservation of P/sub phi/

  14. Magnetic field line random walk in non-axisymmetric turbulence

    International Nuclear Information System (INIS)

    Tautz, R.C.; Lerche, I.

    2011-01-01

    Including a random component of a magnetic field parallel to an ambient field introduces a mean perpendicular motion to the average field line. This effect is normally not discussed because one customarily chooses at the outset to ignore such a field component in discussing random walk and diffusion of field lines. A discussion of the basic effect is given, indicating that any random magnetic field with a non-zero helicity will lead to such a non-zero perpendicular mean motion. Several exact analytic illustrations are given of the effect as well as a simple numerical illustration. -- Highlights: → For magnetic field line random walk all magnetic field components are important. → Non-vanishing magnetic helicity leads to mean perpendicular motion. → Analytically exact stream functions illustrate that the novel transverse effect exists.

  15. Power Take-Off with Integrated Resonator for Energy Extraction from Linear Motions

    DEFF Research Database (Denmark)

    2014-01-01

    The invention relates to a magnetic gear for converting linear motion into rotational motion and vice versa. The present invention converts slow linear irregular oscillating motion of wave energy devices into torque on a high speed shaft for powering a generator while making the wave energy device...... of sea or ocean waves into useful energy, such as electricity. The invention relates to the control and operation of a magnetic gear based motor/generator system. The invention provides a high force density electric powered linear actuator....... resonate with the waves. The invention relates to the field of energy-harvesting from energy sources, where the energy-harvesting requires the extraction of energy from slow and often irregular reciprocating motion of bodies. The present invention relates to a wave power apparatus for converting power...

  16. Determination of 3D magnetic reluctivity tensor of soft magnetic composite material

    International Nuclear Information System (INIS)

    Guo Youguang; Zhu Jianguo; Lin Zhiwei; Zhong Jinjiang; Lu Haiyan; Wang Shuhong

    2007-01-01

    Soft magnetic composite (SMC) materials are especially suitable for construction of electrical machines with complex structures and three-dimensional (3D) magnetic fluxes. In the design and optimization of such 3D flux machines, the 3D vector magnetic properties of magnetic materials should be properly determined, modeled, and applied for accurate calculation of the magnetic field distribution, parameters, and performance. This paper presents the measurement of 3D vector magnetic properties and determination of 3D reluctivity tensor of SMC. The reluctivity tensor is a key factor for accurate numerical analysis of magnetic field in a 3D flux SMC motor

  17. Discrete allowed and forbidden states in the classical mechanical domain in the charged particle motion in a magnetic field

    International Nuclear Information System (INIS)

    Varma, R.K.; Punithavelu, A.M.; Banerjee, S.B.

    1994-01-01

    The properties of the motion of charged particles injected almost parallel to the magnetic field are studied by measuring the electron current as a function of the cathode voltage (electron energy), as electrons from the gun traverse a distance L to the detector. The plate current is found to exhibit oscillatory behaviour in contradistinction with the behaviour expected according to the standard classical mechanical paradigm, with the peaks fitting a relation obtained from a quantum like theory predicting such a behaviour. (author). 4 refs, 1 fig, 1 tab

  18. Optimized respiratory-resolved motion-compensated 3D Cartesian coronary MR angiography.

    Science.gov (United States)

    Correia, Teresa; Ginami, Giulia; Cruz, Gastão; Neji, Radhouene; Rashid, Imran; Botnar, René M; Prieto, Claudia

    2018-04-22

    To develop a robust and efficient reconstruction framework that provides high-quality motion-compensated respiratory-resolved images from free-breathing 3D whole-heart Cartesian coronary magnetic resonance angiography (CMRA) acquisitions. Recently, XD-GRASP (eXtra-Dimensional Golden-angle RAdial Sparse Parallel MRI) was proposed to achieve 100% scan efficiency and provide respiratory-resolved 3D radial CMRA images by exploiting sparsity in the respiratory dimension. Here, a reconstruction framework for Cartesian CMRA imaging is proposed, which provides respiratory-resolved motion-compensated images by incorporating 2D beat-to-beat translational motion information to increase sparsity in the respiratory dimension. The motion information is extracted from interleaved image navigators and is also used to compensate for 2D translational motion within each respiratory phase. The proposed Optimized Respiratory-resolved Cartesian Coronary MR Angiography (XD-ORCCA) method was tested on 10 healthy subjects and 2 patients with cardiovascular disease, and compared against XD-GRASP. The proposed XD-ORCCA provides high-quality respiratory-resolved images, allowing clear visualization of the right and left coronary arteries, even for irregular breathing patterns. Compared with XD-GRASP, the proposed method improves the visibility and sharpness of both coronaries. Significant differences (p respiratory phases with larger motion amplitudes and subjects with irregular breathing patterns. A robust respiratory-resolved motion-compensated framework for Cartesian CMRA has been proposed and tested in healthy subjects and patients. The proposed XD-ORCCA provides high-quality images for all respiratory phases, independently of the regularity of the breathing pattern. © 2018 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

  19. Stochastic motion due to a single wave in a magnetoplasma

    International Nuclear Information System (INIS)

    Smith, G.R.

    1979-01-01

    A single electrostatic wave in a magnetoplasma causes stochastic ion motion in several physically different situations. Various magnetic fields (uniform, tokamak, and mirror) and various propagation angles with respect to the field have been studied. A brief review of this work shows that all situations can be understood using the concept of overlapping resonances. Analytical calculations of the wave amplitude necessary for stochasticity have been carried out in some cases and compared with computer and laboratory experiments. In the case of an axisymmetric mirror field the calculations predict stochastic motion of ions with energy below a threshold that depends weakly on the wave amplitude and on the scale lengths of the magnetic field. Studies with an azimuthally asymmetric field show that the asymmetry causes substantial changes in the motion of some ions

  20. Development of rapid methods for relaxation time mapping and motion estimation using magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Gilani, Syed Irtiza Ali

    2008-09-15

    Recent technological developments in the field of magnetic resonance imaging have resulted in advanced techniques that can reduce the total time to acquire images. For applications such as relaxation time mapping, which enables improved visualisation of in vivo structures, rapid imaging techniques are highly desirable. TAPIR is a Look- Locker-based sequence for high-resolution, multislice T{sub 1} relaxation time mapping. Despite the high accuracy and precision of TAPIR, an improvement in the k-space sampling trajectory is desired to acquire data in clinically acceptable times. In this thesis, a new trajectory, termed line-sharing, is introduced for TAPIR that can potentially reduce the acquisition time by 40 %. Additionally, the line-sharing method was compared with the GRAPPA parallel imaging method. These methods were employed to reconstruct time-point images from the data acquired on a 4T high-field MR research scanner. Multislice, multipoint in vivo results obtained using these methods are presented. Despite improvement in acquisition speed, through line-sharing, for example, motion remains a problem and artefact-free data cannot always be obtained. Therefore, in this thesis, a rapid technique is introduced to estimate in-plane motion. The presented technique is based on calculating the in-plane motion parameters, i.e., translation and rotation, by registering the low-resolution MR images. The rotation estimation method is based on the pseudo-polar FFT, where the Fourier domain is composed of frequencies that reside in an oversampled set of non-angularly, equispaced points. The essence of the method is that unlike other Fourier-based registration schemes, the employed approach does not require any interpolation to calculate the pseudo-polar FFT grid coordinates. Translation parameters are estimated by the phase correlation method. However, instead of two-dimensional analysis of the phase correlation matrix, a low complexity subspace identification of the phase

  1. Development of rapid methods for relaxation time mapping and motion estimation using magnetic resonance imaging

    International Nuclear Information System (INIS)

    Gilani, Syed Irtiza Ali

    2008-09-01

    Recent technological developments in the field of magnetic resonance imaging have resulted in advanced techniques that can reduce the total time to acquire images. For applications such as relaxation time mapping, which enables improved visualisation of in vivo structures, rapid imaging techniques are highly desirable. TAPIR is a Look- Locker-based sequence for high-resolution, multislice T 1 relaxation time mapping. Despite the high accuracy and precision of TAPIR, an improvement in the k-space sampling trajectory is desired to acquire data in clinically acceptable times. In this thesis, a new trajectory, termed line-sharing, is introduced for TAPIR that can potentially reduce the acquisition time by 40 %. Additionally, the line-sharing method was compared with the GRAPPA parallel imaging method. These methods were employed to reconstruct time-point images from the data acquired on a 4T high-field MR research scanner. Multislice, multipoint in vivo results obtained using these methods are presented. Despite improvement in acquisition speed, through line-sharing, for example, motion remains a problem and artefact-free data cannot always be obtained. Therefore, in this thesis, a rapid technique is introduced to estimate in-plane motion. The presented technique is based on calculating the in-plane motion parameters, i.e., translation and rotation, by registering the low-resolution MR images. The rotation estimation method is based on the pseudo-polar FFT, where the Fourier domain is composed of frequencies that reside in an oversampled set of non-angularly, equispaced points. The essence of the method is that unlike other Fourier-based registration schemes, the employed approach does not require any interpolation to calculate the pseudo-polar FFT grid coordinates. Translation parameters are estimated by the phase correlation method. However, instead of two-dimensional analysis of the phase correlation matrix, a low complexity subspace identification of the phase

  2. Results of stretched wire field integral measurements on the mini-undulator magnet - comparison of results obtained from circular and translational motion of the integrating wire

    International Nuclear Information System (INIS)

    Solomon, L.

    1998-05-01

    Measurements of the multipole content of the Mini-Undulator magnet have been made with two different integrating wire techniques. Both measurements used 43 strand Litz wire stretched along the length of the magnet within the magnet gap. In the first technique, the wire motion was purely translational, while in the second technique the wire was moved along a circular path. The induced voltage in the Litz wire was input into a Walker integrator, and the integrator output was analyzed as a function of wire position for determination of the multipole content of the magnetic field. The mini-undulator magnet is a 10 period, 80 mm per period hybrid insertion device. For all the data contained herein the magnet gap was set at 49 mm. In the mini-undulator magnet, the iron poles are 18mm x 32mm x 86 mm, and the Samarium Cobalt permanent magnet blocks are 22mm x 21mm x 110mm. For this magnet, which is a shortened prototype for the NSLS Soft X-Ray Undulator Magnet, the undulator parameter K = 0.934 B (Tesla)λ(cm), and B(tesla) = 0.534/sinh(πGap/λ). At a gap of 49 mm, the magnetic field is 1590 Gauss

  3. A navigator-based rigid body motion correction for magnetic resonance imaging

    International Nuclear Information System (INIS)

    Ullisch, Marcus Goerge

    2012-01-01

    A novel three-dimensional navigator k-space trajectory for rigid body motion detection for Magnetic Resonance Imaging (MRI) - the Lissajous navigator - was developed and quantitatively compared to the existing spherical navigator trajectory [1]. The spherical navigator cannot sample the complete spherical surface due to slew rate limitations of the scanner hardware. By utilizing a two dimensional Lissajous figure which is projected onto the spherical surface, the Lissajous navigator overcomes this limitation. The complete sampling of the sphere consequently leads to rotation estimates with higher and more isotropic accuracy. Simulations and phantom measurements were performed for both navigators. Both simulations and measurements show a significantly higher overall accuracy of the Lissajous navigator and a higher isotropy of the rotation estimates. Measured under identical conditions with identical postprocessing, the measured mean absolute error of the rotation estimates for the Lissajous navigator was 38% lower (0.3 ) than for the spherical navigator (0.5 ). The maximum error of the Lissajous navigator was reduced by 48% relative to the spherical navigator. The Lissajous navigator delivers higher accuracy of rotation estimation and a higher degree of isotropy than the spherical navigator with no evident drawbacks; these are two decisive advantages, especially for high-resolution anatomical imaging.

  4. A navigator-based rigid body motion correction for magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ullisch, Marcus Goerge

    2012-01-24

    A novel three-dimensional navigator k-space trajectory for rigid body motion detection for Magnetic Resonance Imaging (MRI) - the Lissajous navigator - was developed and quantitatively compared to the existing spherical navigator trajectory [1]. The spherical navigator cannot sample the complete spherical surface due to slew rate limitations of the scanner hardware. By utilizing a two dimensional Lissajous figure which is projected onto the spherical surface, the Lissajous navigator overcomes this limitation. The complete sampling of the sphere consequently leads to rotation estimates with higher and more isotropic accuracy. Simulations and phantom measurements were performed for both navigators. Both simulations and measurements show a significantly higher overall accuracy of the Lissajous navigator and a higher isotropy of the rotation estimates. Measured under identical conditions with identical postprocessing, the measured mean absolute error of the rotation estimates for the Lissajous navigator was 38% lower (0.3 ) than for the spherical navigator (0.5 ). The maximum error of the Lissajous navigator was reduced by 48% relative to the spherical navigator. The Lissajous navigator delivers higher accuracy of rotation estimation and a higher degree of isotropy than the spherical navigator with no evident drawbacks; these are two decisive advantages, especially for high-resolution anatomical imaging.

  5. Single-molecule magnets on a polymeric thin film as magnetic quantum bits

    Science.gov (United States)

    Ruiz-Molina, Daniel; Gomez, Jordi; Mas-Torrent, Marta; Balana, Ana Isabel; Domingo, Nues; Tejada, Javier; Martinez, Maria Teresa; Rovira, Concepcio; Veciana, Jaume

    2003-04-01

    Single-molecule magnets (SMM) have a large-spin ground state with appreciable magnetic anisotropy, resulting in a barrier for the spin reversal As a consequence, interesting magnetic properties such as out-of-phase ac magnetic susceptibility signals and stepwise magnetization hysteresis loops are observed. In addition to resonant magnetization tunnelling, during the last few years several other interesting phenomena have also been reported. The origin of the slow magnetization relaxation rates as well as of other phenomena are due to individual molecules rather than to long-range ordering; as confirmed by magnetization relaxation and heat capacity studies. Therefore, SMM represent nanoscale magnetic particles of a sharply defined size that offer the potential access to the ultimate high-density information storage devices as well as for quantum computing applications. However, if a truly molecular computational device based on SMM is to be achieved, new systematic studies that allow us to find a proper way to address properly oriented individual molecules or molecular aggregates onto the surface of a thin film, where each molecule or molecular aggregate can be used as a bit of information, are highly required. Here we report a new soft, reliable and simple methodology to address individual Mn12 molecules onto a film surface, as revealed by Atomic Force Microscopy (AFM) and Magnetic Force Microscopy (MFM) images. Moreover, the advantageous properties of polymeric matrices, such as flexibility, transparency and low density, make this type of materials very interesting for potential applications.

  6. A novel automated device for rapid nucleic acid extraction utilizing a zigzag motion of magnetic silica beads

    International Nuclear Information System (INIS)

    Yamaguchi, Akemi; Matsuda, Kazuyuki; Uehara, Masayuki; Honda, Takayuki; Saito, Yasunori

    2016-01-01

    We report a novel automated device for nucleic acid extraction, which consists of a mechanical control system and a disposable cassette. The cassette is composed of a bottle, a capillary tube, and a chamber. After sample injection in the bottle, the sample is lysed, and nucleic acids are adsorbed on the surface of magnetic silica beads. These magnetic beads are transported and are vibrated through the washing reagents in the capillary tube under the control of the mechanical control system, and thus, the nucleic acid is purified without centrifugation. The purified nucleic acid is automatically extracted in 3 min for the polymerase chain reaction (PCR). The nucleic acid extraction is dependent on the transport speed and the vibration frequency of the magnetic beads, and optimizing these two parameters provided better PCR efficiency than the conventional manual procedure. There was no difference between the detection limits of our novel device and that of the conventional manual procedure. We have already developed the droplet-PCR machine, which can amplify and detect specific nucleic acids rapidly and automatically. Connecting the droplet-PCR machine to our novel automated extraction device enables PCR analysis within 15 min, and this system can be made available as a point-of-care testing in clinics as well as general hospitals. - Highlights: • Automatic nucleic acid extraction is performed in 3 min. • Zigzag motion of magnetic silica beads yields rapid and efficient extraction. • The present our device provides better performance than the conventional procedure.

  7. Dynamics of magnetic particles in cylindrical Halbach array: implications for magnetic cell separation and drug targeting.

    Science.gov (United States)

    Babinec, Peter; Krafcík, Andrej; Babincová, Melánia; Rosenecker, Joseph

    2010-08-01

    Magnetic nanoparticles for therapy and diagnosis are at the leading edge of the rapidly developing field of bionanotechnology. In this study, we have theoretically studied motion of magnetic nano- as well as micro-particles in the field of cylindrical Halbach array of permanent magnets. Magnetic flux density was modeled as magnetostatic problem by finite element method and particle motion was described using system of ordinary differential equations--Newton law. Computations were done for nanoparticles Nanomag-D with radius 65 nm, which are often used in magnetic drug targeting, as well as microparticles DynaBeads-M280 with radius 1.4 microm, which can be used for magnetic separation. Analyzing snapshots of trajectories of hundred magnetite particles of each size in the water as well as in the air, we have found that optimally designed magnetic circuits of permanent magnets in quadrupolar Halbach array have substantially shorter capture time than simple blocks of permanent magnets commonly used in experiments, therefore, such a Halbach array may be useful as a potential source of magnetic field for magnetic separation and targeting of magnetic nanoparticles as well as microparticles for delivery of drugs, genes, and cells in various biomedical applications.

  8. Current-induced magnetic switching of a single molecule magnet on a spin valve

    International Nuclear Information System (INIS)

    Zhang, Xiao; Wang, Zheng-Chuan; Zheng, Qing-Rong; Zhu, Zheng-Gang; Su, Gang

    2015-01-01

    The current-induced magnetic switching of a single-molecule magnet (SMM) attached on the central region of a spin valve is explored, and the condition for the switching current is derived. Electrons flowing through the spin valve will interact with the SMM via the s–d exchange interaction, producing the spin accumulation that satisfies the spin diffusion equation. We further describe the spin motion of the SMM by a Heisenberg-like equation. Based on the linear stability analysis, we obtain the critical current from two coupled equations. The results of the critical current versus the external magnetic field indicate that one can manipulate the magnetic state of the SMM by an external magnetic field. - Highlights: • We theoretically study the current-induced magnetic switching of the SMM. • We describe the spin motion of the SMM by a Heisenberg-like equation. • We describe the spin accumulation by the spin diffusion equation. • We obtain the critical current by the linear stability analysis. • Our approach can be easily extended to other SMMs

  9. Current-induced magnetic switching of a single molecule magnet on a spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiao [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Zheng-Chuan, E-mail: wangzc@ucas.ac.cn [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Zheng, Qing-Rong [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Zhu, Zheng-Gang [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); School of Electronics, Electric and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049 (China); Su, Gang, E-mail: gsu@ucas.ac.cn [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China)

    2015-04-17

    The current-induced magnetic switching of a single-molecule magnet (SMM) attached on the central region of a spin valve is explored, and the condition for the switching current is derived. Electrons flowing through the spin valve will interact with the SMM via the s–d exchange interaction, producing the spin accumulation that satisfies the spin diffusion equation. We further describe the spin motion of the SMM by a Heisenberg-like equation. Based on the linear stability analysis, we obtain the critical current from two coupled equations. The results of the critical current versus the external magnetic field indicate that one can manipulate the magnetic state of the SMM by an external magnetic field. - Highlights: • We theoretically study the current-induced magnetic switching of the SMM. • We describe the spin motion of the SMM by a Heisenberg-like equation. • We describe the spin accumulation by the spin diffusion equation. • We obtain the critical current by the linear stability analysis. • Our approach can be easily extended to other SMMs.

  10. Auditory motion-specific mechanisms in the primate brain.

    Directory of Open Access Journals (Sweden)

    Colline Poirier

    2017-05-01

    Full Text Available This work examined the mechanisms underlying auditory motion processing in the auditory cortex of awake monkeys using functional magnetic resonance imaging (fMRI. We tested to what extent auditory motion analysis can be explained by the linear combination of static spatial mechanisms, spectrotemporal processes, and their interaction. We found that the posterior auditory cortex, including A1 and the surrounding caudal belt and parabelt, is involved in auditory motion analysis. Static spatial and spectrotemporal processes were able to fully explain motion-induced activation in most parts of the auditory cortex, including A1, but not in circumscribed regions of the posterior belt and parabelt cortex. We show that in these regions motion-specific processes contribute to the activation, providing the first demonstration that auditory motion is not simply deduced from changes in static spatial location. These results demonstrate that parallel mechanisms for motion and static spatial analysis coexist within the auditory dorsal stream.

  11. Motion of magnetotactic microorganisms

    International Nuclear Information System (INIS)

    Esquivel, D.M.S.; Barros, H.G. de P.L. de.

    1985-01-01

    Magnetic moments for different magnetotactic microorganisms are obtained by electron microscopy analyses and studies of motion by optical microscopy. The results are analysed in terms of a model due to C.Bean. The considerations presented suggest that magnetotaxy is an efficient mechanism for orientation only if the time for reorientation is smaller than the cycles of environmental perturbations. (Author) [pt

  12. Magnetic Thermometer: Thermal effect on the Agglomeration of Magnetic Nanoparticles by Magnetic field

    Science.gov (United States)

    Jin, Daeseong; Kim, Hackjin

    2018-03-01

    We have investigated the agglomeration of magnetite nanoparticles in the aqueous solution under magnetic field by measuring temporal change of magnetic weight. The magnetic weight corresponds to the force due to the magnetization of magnetic materials. Superparamagnetic magnetite nanoparticles are synthesized and used in this work. When the aqueous solution of magnetite nanoparticle is placed under magnetic field, the magnetic weight of the sample jumps instantaneously by Neel and Brown mechanisms and thereafter increases steadily following a stretched exponential function as the nanoparticles agglomerate, which results from the distribution of energy barriers involved in the dynamics. Thermal motions of nanoparticles in the agglomerate perturb the ordered structure of the agglomerate to reduce the magnetic weight. Fluctuation of the structural order of the agglomerate by temperature change is much faster than the formation of agglomerate and explained well with the Boltzmann distribution, which suggests that the magnetic weight of the agglomerate works as a magnetic thermometer.

  13. Application of inertial sensors for motion analysis

    Directory of Open Access Journals (Sweden)

    Ferenc Soha

    2012-06-01

    Full Text Available This paper presents our results on the application of various inertial sensors for motion analysis. After the introduction of different sensor types (accelerometer, gyroscope, magnetic field sensor, we discuss the possible data collection and transfer techniques using embedded signal processing and wireless data communication methods [1,2]. Special consideration is given to the interpretation of accelerometer readings, which contains both the static and dynamic components, and is affected by the orientation and rotation of the sensor. We will demonstrate the possibility to decompose these components for quasiperiodic motions. Finally we will demonstrate the application of commercially available devices (Wii sensor, Kinect sensor, mobile phone for motion analysis applications.

  14. Repulsion analysis of permanent magnets for the Hoop energy storage system

    International Nuclear Information System (INIS)

    O, B. H.; Cho, S. B.; Kim, D. I.

    1996-01-01

    The repulsion force of permanent magnets is studied in order to analyze the instability problem of the rotational motion of a hoop levitated by permanent magnets in the Hoop Energy Storage System (HESS). The hoop of permanent magnets is levitated to remove the mechanical complexities caused by the rotational axis. It is important to maintain stable rotational motion at any speed for the efficiency as well as the safety of the system. To set up the equations of motion, the force of levitation and the source of perturbation are represented in terms of real parameters of the permanent magnets. The instability conditions and various geometric effects of the permanent magnets are analyzed. (author)

  15. The dynamic behavior of magnetic fluid adsorbed to small permanent magnet in alternating magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sudo, Seiichi, E-mail: sudo@akita-pu.ac.j [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Asano, Daisaku [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Takana, Hidemasa; Nishiyama, Hideya [Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aobaku, Sendai 980-8577 (Japan)

    2011-05-15

    The dynamic behavior of a magnetic fluid adsorbed to a small NdFeB permanent magnet subjected to an alternating magnetic field was studied with a high speed video camera system. The directions of alternating magnetic field are parallel and opposite to that of the permanent magnet. It was found that the surface of magnetic fluid responds to the external alternating magnetic field in elongation and contraction with a lot of spikes. Generation of a capillary magnetic fluid jet was observed in the neighbourhood of a specific frequency of alternating field. The effect of gravitational force on surface phenomena of magnetic fluid adsorbed to the permanent magnet was revealed. - Research Highlights: Magnetic fluid of the system responds to alternating magnetic field with higher frequencies. Large-amplitude surface motions of magnetic fluid occur at the specific frequencies of the external field. Capillary jets of magnetic fluid are generated at the natural frequency of the system.

  16. Evaluation of motion and its effect on brain magnetic resonance image quality in children

    Energy Technology Data Exchange (ETDEWEB)

    Afacan, Onur; Erem, Burak; Roby, Diona P.; Prabhu, Sanjay P.; Warfield, Simon K. [Boston Children' s Hospital and Harvard Medical School, Department of Radiology, Boston, MA (United States); Roth, Noam; Roth, Amir [Robin Medical Inc., Baltimore, MD (United States)

    2016-11-15

    Motion artifacts pose significant problems for the acquisition of MR images in pediatric populations. To evaluate temporal motion metrics in MRI scanners and their effect on image quality in pediatric populations in neuroimaging studies. We report results from a large pediatric brain imaging study that shows the effect of motion on MRI quality. We measured motion metrics in 82 pediatric patients, mean age 13.4 years, in a T1-weighted brain MRI scan. As a result of technical difficulties, 5 scans were not included in the subsequent analyses. A radiologist graded the images using a 4-point scale ranging from clinically non-diagnostic because of motion artifacts to no motion artifacts. We used these grades to correlate motion parameters such as maximum motion, mean displacement from a reference point, and motion-free time with image quality. Our results show that both motion-free time (as a ratio of total scan time) and average displacement from a position at a fixed time (when the center of k-space was acquired) were highly correlated with image quality, whereas maximum displacement was not as good a predictor. Among the 77 patients whose motion was measured successfully, 17 had average displacements of greater than 0.5 mm, and 11 of those (14.3%) resulted in non-diagnostic images. Similarly, 14 patients (18.2%) had less than 90% motion-free time, which also resulted in non-diagnostic images. We report results from a large pediatric study to show how children and young adults move in the MRI scanner and the effect that this motion has on image quality. The results will help the motion-correction community in better understanding motion patterns in pediatric populations and how these patterns affect MR image quality. (orig.)

  17. Evaluation of motion and its effect on brain magnetic resonance image quality in children

    International Nuclear Information System (INIS)

    Afacan, Onur; Erem, Burak; Roby, Diona P.; Prabhu, Sanjay P.; Warfield, Simon K.; Roth, Noam; Roth, Amir

    2016-01-01

    Motion artifacts pose significant problems for the acquisition of MR images in pediatric populations. To evaluate temporal motion metrics in MRI scanners and their effect on image quality in pediatric populations in neuroimaging studies. We report results from a large pediatric brain imaging study that shows the effect of motion on MRI quality. We measured motion metrics in 82 pediatric patients, mean age 13.4 years, in a T1-weighted brain MRI scan. As a result of technical difficulties, 5 scans were not included in the subsequent analyses. A radiologist graded the images using a 4-point scale ranging from clinically non-diagnostic because of motion artifacts to no motion artifacts. We used these grades to correlate motion parameters such as maximum motion, mean displacement from a reference point, and motion-free time with image quality. Our results show that both motion-free time (as a ratio of total scan time) and average displacement from a position at a fixed time (when the center of k-space was acquired) were highly correlated with image quality, whereas maximum displacement was not as good a predictor. Among the 77 patients whose motion was measured successfully, 17 had average displacements of greater than 0.5 mm, and 11 of those (14.3%) resulted in non-diagnostic images. Similarly, 14 patients (18.2%) had less than 90% motion-free time, which also resulted in non-diagnostic images. We report results from a large pediatric study to show how children and young adults move in the MRI scanner and the effect that this motion has on image quality. The results will help the motion-correction community in better understanding motion patterns in pediatric populations and how these patterns affect MR image quality. (orig.)

  18. Optical motion control of maglev graphite.

    Science.gov (United States)

    Kobayashi, Masayuki; Abe, Jiro

    2012-12-26

    Graphite has been known as a typical diamagnetic material and can be levitated in the strong magnetic field. Here we show that the magnetically levitating pyrolytic graphite can be moved in the arbitrary place by simple photoirradiation. It is notable that the optical motion control system described in this paper requires only NdFeB permanent magnets and light source. The optical movement is driven by photothermally induced changes in the magnetic susceptibility of the graphite. Moreover, we demonstrate that light energy can be converted into rotational kinetic energy by means of the photothermal property. We find that the levitating graphite disk rotates at over 200 rpm under the sunlight, making it possible to develop a new class of light energy conversion system.

  19. Study of magnetization reversal processes in a thin Co film

    International Nuclear Information System (INIS)

    Chowdhury, N.; Bedanta, S.; Babu, G.S.

    2013-01-01

    The magnetization reversal has been studied both along the easy- and hard- axes for an in plane magnetized thin Cobalt film using magneto-optical Kerr effect (MOKE) microscope. We observe that magnetization reversal is governed by domain wall motion accompanied by nucleation when measured along the easy axis. However coherent rotation is observed during magnetization reversal when measured along the hard axis. The relaxation of magnetization in constant dc magnetic field measured along the easy axis shows exponential behaviour which according to Fatuzzo–Labrune model indicates domain nucleated dominant process. Domain wall velocity plotted as a function of constant dc magnetic field shows creep and slide regime from which the depinning transition was extracted. - Highlights: ► Kerr microscopy was performed for different field orientation to the easy axis. ► Here we have measured domain wall velocity in constant dc fields. ► Creep, depinning and slide modes of domain wall motion have been observed. ► Magnetic relaxation data can be very well fitted to Fatuzzo–Labrune model. ► Magnetization reversal occurs via domain nucleation and wall motion

  20. Some analyses on the plasma motion in the space active region of the axial symmetry

    International Nuclear Information System (INIS)

    Li Zhongyuan; Hu Wenrui.

    1986-04-01

    In general, the potential magnetic field may gradually be twisted into the force-free magnetic field with the current produced by plasma rotation. In this paper, it is pointed out that if the magnetic field has no singularity on the symmetric axis, then the potential magnetic field cannot be twisted into the force-free magnetic field. Namely, it is not a perfect approach that the energy storage is only caused by the pure azimuthal motion in the active region. Besides the pure spiral motion, the unsteady coupling process between the magnetic field and both the toroidal and the poloidal velocity components should be analyzed. Finally, in the present note, some features of the kinematical force-free magnetic field of the axial symmetry are presented by the authors. (author)

  1. Magnetic Resonance-based Motion Correction for Quantitative PET in Simultaneous PET-MR Imaging.

    Science.gov (United States)

    Rakvongthai, Yothin; El Fakhri, Georges

    2017-07-01

    Motion degrades image quality and quantitation of PET images, and is an obstacle to quantitative PET imaging. Simultaneous PET-MR offers a tool that can be used for correcting the motion in PET images by using anatomic information from MR imaging acquired concurrently. Motion correction can be performed by transforming a set of reconstructed PET images into the same frame or by incorporating the transformation into the system model and reconstructing the motion-corrected image. Several phantom and patient studies have validated that MR-based motion correction strategies have great promise for quantitative PET imaging in simultaneous PET-MR. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Stochastic acceleration by a single wave in a magnetized plasma

    International Nuclear Information System (INIS)

    Smith, R.

    1977-01-01

    A particularly simple problem exhibiting stochasticity is the motion of a charged particle in a uniform magnetic field and a single wave. Detailed studies of this wave-particle interaction show the following features. An electrostatic wave propagating obliquely to the magnetic field causes stochastic motion if the wave amplitude exceeds a certain threshold. The overlap of cyclotron resonances then destroys a constant of the motion, allowing strong particle acceleration. A wave of large enough amplitude would thus suffer severe damping and lead to rapid heating of a particle distribution. The stochastic motion resembles a diffusion process even though the wave spectrum contains only a single wave. The motion of ions in a nonuniform magnetic field and a single electrostatic wave is treated in our study of a possible saturation mechanism of the dissipative trapped-ion instability in a tokamak. A theory involving the overlap of bounce resonances predicts the main features found in the numerical integration of the equations of motion. Ions in a layer near the trapped-circulating boundary move stochastically. This motion leads to nonlinear stabilization mechanisms which are described qualitatively

  3. The apparent motion of the Sun revisited

    Science.gov (United States)

    Probst, Oliver

    2002-05-01

    The knowledge of the apparent motion of the Sun - due to the combined effects of the rotation of the Earth around its proper axis and the translation around the Sun - is important both in natural and man-made systems. In particular, a proper explanation of the seasons requires an understanding of this solar geometry. In this paper we present a simple derivation of the relevant formulae based on vector algebra. The possible trajectories are discussed in detail. An approximate explicit formula for the seasonal variations of solar radiation is derived and discussed. The calculations give useful insights into the geometry of the problem and are thought to be helpful for the undergraduate teaching of solar energy engineering, classical mechanics and astronomy.

  4. On the propagation and stability of wave motions in rapidly rotating spherical shells. 2. Hydromagnetic two-dimensional motions

    International Nuclear Information System (INIS)

    Eltayeb, I.A.

    1983-07-01

    The linear progation properties and stability of wave motions in spherical shells examined in paper I (Geophys. Astr. Fluid Dyn., 16, 129) are here extended to the case of a toroidal magnetic field together with an associated shear flow. The analysis is restricted to moderate values of the magnetic field amplitude, in which case the ensuing motions are two-dimensional. They occur in thin cylindrical cells coaxial with the axis of rotation. For every set of the relevant parameters an infinity of modes exists and is divided into two uncoupled categories. One category is associated with a temperature perturbation even in the axial coordinate z and the other category odd in z. In the presence of an inner solid core the even set persists only outside the cylindrical surface, Csub(c), whose generators touch the inner core at its equator while the odd set persists everywhere. The direction of propagation of these waves depends on the ratio, q, of thermal to magnetic diffusivities and on the modified Chandrasekhar number Q (which is the ratio of Lorentz to Coriolis forces). For small values of q relevant to geophysical applications both eastward and westward propagation is possible if Q is small; but as Q increases beyond a certain value, only eastward propagation is possible. For the case of large q applicable to astrophysical situations both eastward and westward propagation is possible. All these results apply for a variety of temperature gradients in which both internal and differential forms of heating are invoked, and various forms of toroidal magnetic fields. The stability of these wave motions is examined and the most preferred mode of convection is identified in each case. The unstable cell always lies on Csub(c) or outside it. Its precise location depends on the types of magnetic field and temperature gradient. The sloping boundary of the spherical shell tends to stabilize westward propagating waves

  5. Magnetic flux motion in (PrxY1−xBa2Cu3O7−δ polycrystal samples sintered in Ar and O2 atmospheres

    Directory of Open Access Journals (Sweden)

    S. Favre

    2016-09-01

    Full Text Available We present a comparative study of the magnetic flux motion in ceramic pellets made of (PrxY1−xBa2Cu3O7−δ as a function of their composition and morphology. Samples produced in Ar or O2 atmosphere present noticeable differences in their magnetic response that we explain in terms of their structural parameters. The material’s parameters that most influence the flux dynamics are morphology and oxygen content, that change dramatically with the sintering atmosphere. Moderate changes are also observed as a function of the Pr content. Magnetic pinning efficiency is discussed in terms of intergranular couplings and effective activation energies, estimated from AC-susceptibility and magnetoresistance measurements.

  6. Micromagnetic simulation for the magnetization reversal process of Nd-Fe-B hot-deformed nanocrystalline permanent magnets

    Directory of Open Access Journals (Sweden)

    Hiroshi Tsukahara

    2017-05-01

    Full Text Available We numerically demonstrated the magnetization reversal process inside a hot-deformed nanocrystalline permanent magnet. We performed large-scale micromagnetics simulation based on the Landau–Lifshitz–Gilbert equation with 0.1 billion calculation cells. The simulation model for the hot-deformed nanocrystalline permanent magnet consists of 2622 tabular grains that interact with each other by inter-grain exchange and dipole interactions. When the strength of the external field approached a coercive force, nucleation cores were created at the grain surface. The magnetization reversal was propagated by the inter-grain and dipole interactions. When the grains had overlapping regions parallel to the external field, the magnetization reversal propagated quickly between the grains due to the dipole interaction. In contrast, the motion of the magnetic domain wall was inhibited at interfaces between the grains perpendicular to the external field. Reversal magnetic domains had a pillar-shaped structure that is parallel to the external field. In the perpendicular direction, the reversal magnetic domain expanded gradually because of the inhibition of the domain wall motion.

  7. Analysing harmonic motions with an iPhone’s magnetometer

    Science.gov (United States)

    Yavuz, Ahmet; Kağan Temiz, Burak

    2016-05-01

    In this paper, we propose an experiment for analysing harmonic motion using an iPhone’s (or iPad’s) magnetometer. This experiment consists of the detection of magnetic field variations obtained from an iPhone’s magnetometer sensor. A graph of harmonic motion is directly displayed on the iPhone’s screen using the Sensor Kinetics application. Data from this application was analysed with Eureqa software to establish the equation of the harmonic motion. Analyses show that the use of an iPhone’s magnetometer to analyse harmonic motion is a practical and effective method for small oscillations and frequencies less than 15-20 Hz.

  8. VERY SLOW SPEED AXIAL MOTION RELUCTANCE MOTOR

    African Journals Online (AJOL)

    Dr Obe

    1984-09-01

    Sep 1, 1984 ... VERY SLOW SPEED AXIAL MOTION RELUCTANCE MOTOR by. L. A. Agu ... order as that of the screw-thread motor can be obtained. LIST OF .... The n stator have equal non- magnetic spacers .... induction motor. An.

  9. The direct, not V1-mediated, functional influence between the thalamus and middle temporal complex in the human brain is modulated by the speed of visual motion.

    Science.gov (United States)

    Gaglianese, A; Costagli, M; Ueno, K; Ricciardi, E; Bernardi, G; Pietrini, P; Cheng, K

    2015-01-22

    The main visual pathway that conveys motion information to the middle temporal complex (hMT+) originates from the primary visual cortex (V1), which, in turn, receives spatial and temporal features of the perceived stimuli from the lateral geniculate nucleus (LGN). In addition, visual motion information reaches hMT+ directly from the thalamus, bypassing the V1, through a direct pathway. We aimed at elucidating whether this direct route between LGN and hMT+ represents a 'fast lane' reserved to high-speed motion, as proposed previously, or it is merely involved in processing motion information irrespective of speeds. We evaluated functional magnetic resonance imaging (fMRI) responses elicited by moving visual stimuli and applied connectivity analyses to investigate the effect of motion speed on the causal influence between LGN and hMT+, independent of V1, using the Conditional Granger Causality (CGC) in the presence of slow and fast visual stimuli. Our results showed that at least part of the visual motion information from LGN reaches hMT+, bypassing V1, in response to both slow and fast motion speeds of the perceived stimuli. We also investigated whether motion speeds have different effects on the connections between LGN and functional subdivisions within hMT+: direct connections between LGN and MT-proper carry mainly slow motion information, while connections between LGN and MST carry mainly fast motion information. The existence of a parallel pathway that connects the LGN directly to hMT+ in response to both slow and fast speeds may explain why MT and MST can still respond in the presence of V1 lesions. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  10. Image-based synchronization of force and bead motion in active electromagnetic microrheometry

    International Nuclear Information System (INIS)

    Park, Chang-Young; Saleh, Omar A

    2014-01-01

    In the past, electromagnetic tweezers have been used to make active microrheometers. An active microrheometer measures the dynamic mechanical properties of a material from the motion of embedded particles under external force, e.g. a sinusoidal magnetic force generated by a sinusoidal current on a coil. The oscillating amplitude and the phase lag of the motion are then used to estimate the material’s dynamic mechanical properties. The phase lag, in particular, requires precise synchronization of the particle motion with the external force. In previous works, synchronization difficulties have arisen from measuring two parameters with two instruments, one of them being a camera. We solved the synchronization issue by measuring two parameters with a single instrument, the camera alone. From captured images, particles can be tracked in three dimensions through an image-analysis algorithm while the current on the coil can be measured from the brightness of the image; this enables simultaneous synchronization of the phases of the driving current on the electromagnet coil and the motion of the magnetic probe particle. We calibrate the phase delay between the magnetic force and the particle’s motion in glycerol and confirm the calibration with a Hall probe. The technique is further tested by measuring the shear modulus of a polyacrylamide gel, and comparing the results to those obtained using a conventional rheometer. (paper)

  11. Quantum mechanical equations of particle and spin motion in polarised medium

    International Nuclear Information System (INIS)

    Silenko, A.Ya.

    2003-01-01

    The quantum mechanical equations for the particles and spin motion in the media with polarized electrons by presence of the external fields are determined. The motion of the electrons and their spin are influenced by the exchange interaction whereas the motion of the positrons is the annihilation one. The second order summands by spin are accounted for the particles with the S≥1 spin. The obtained equations may applied for describing the particles and spin motion both in the magnetic and nonmagnetic media [ru

  12. High efficiency of the spin-orbit torques induced domain wall motion in asymmetric interfacial multilayered Tb/Co wires

    International Nuclear Information System (INIS)

    Bang, Do; Awano, Hiroyuki

    2015-01-01

    We investigated current-induced DW motion in asymmetric interfacial multilayered Tb/Co wires for various thicknesses of magnetic and Pt-capping layers. It is found that the driving mechanism for the DW motion changes from interfacial to bulk effects at much thick magnetic layer (up to 19.8 nm). In thin wires, linearly depinning field dependence of critical current density and in-plane field dependence of DW velocity suggest that the extrinsic pinning governs field-induced DW motion and injecting current can be regarded as an effective field. It is expected that the high efficiency of spin-orbit torques in thick magnetic multilayers would have important implication for future spintronic devices based on in-plane current induced-DW motion or switching

  13. High efficiency of the spin-orbit torques induced domain wall motion in asymmetric interfacial multilayered Tb/Co wires

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Do, E-mail: bang@spin.mp.es.osaka-u.ac.jp [Toyota Technological Institute, Tempaku, Nagoya 468-8511 (Japan); Institute of Materials Science, VAST, 18 Hoang Quoc Viet, Hanoi (Viet Nam); Awano, Hiroyuki [Toyota Technological Institute, Tempaku, Nagoya 468-8511 (Japan)

    2015-05-07

    We investigated current-induced DW motion in asymmetric interfacial multilayered Tb/Co wires for various thicknesses of magnetic and Pt-capping layers. It is found that the driving mechanism for the DW motion changes from interfacial to bulk effects at much thick magnetic layer (up to 19.8 nm). In thin wires, linearly depinning field dependence of critical current density and in-plane field dependence of DW velocity suggest that the extrinsic pinning governs field-induced DW motion and injecting current can be regarded as an effective field. It is expected that the high efficiency of spin-orbit torques in thick magnetic multilayers would have important implication for future spintronic devices based on in-plane current induced-DW motion or switching.

  14. Domain wall manipulation in magnetic nanotubes induced by electric current pulses

    International Nuclear Information System (INIS)

    Otálora, J A; López-López, J A; Landeros, P; Núñez, A S

    2012-01-01

    We propose that the injection of electric currents can be used to independently manipulate the position and chirality of vortex-like domain walls in metallic ferromagnetic nanotubes. We support this proposal upon theoretical and numerical assessment of the magnetization dynamics driven by such currents. We show that proper interplay between the tube geometry, magnitude of the electric current and the duration of a current pulse, can be used to manipulate the position, velocity and chirality of a vortex domain wall. Our calculations suggest that domain wall velocities greater than 1 km s -1 can be achieved for tube diameters of the order of 30 nm and increasing with it. We also find that the transition from steady to precessional domain wall motion occurs for very high electric current densities, of the order of 10 13 A m -2 . Furthermore, the great stability displayed by such chiral magnetic configurations, and the reduced Ohmic loses provided by the current pulses, lead to highly reproducible and efficient domain wall reversal mechanisms.

  15. Levitation of a magnet by an alternating magnetic field

    International Nuclear Information System (INIS)

    Gough, W; Hunt, M O; Summerskill, W S H

    2013-01-01

    An experiment is described in which a small strong cylindrical magnet is levitated by a vertical non-uniform alternating magnetic field. Surprisingly, no superimposed constant field is necessary, but the levitation can be explained when the vertical motion of the magnet is taken into account. The theoretical mean levitation force is (0.26 ± 0.06) N, which is in good agreement with the levitated weight of (0.239 ± 0.001) N. This experiment is suitable for an undergraduate laboratory, particularly as a final year project. Students have found it interesting, and it sharpens up knowledge of basic magnetism. (paper)

  16. The fall of the Northern Unicorn: Tangential motions in the Galactic Anti-centre with SDSS and Gaia

    OpenAIRE

    de Boer, T. J. L.; Belokurov, V.; Koposov, S. E.

    2017-01-01

    We present the first detailed study of the behaviour of the stellar proper motion across the entire Galactic Anti-centre area visible in the Sloan Digital Sky Survey data. We use recalibrated SDSS astrometry in combination with positions from {\\it Gaia} DR1 to provide tangential motion measurements with a systematic uncertainty $

  17. Ion Motion in a Plasma Interacting with Strong Magnetic Fields

    International Nuclear Information System (INIS)

    Weingarten, A.; Grabowski, C.; Chakrabarti, N.; Maron, Y.; Fruchtmant, A.

    1999-01-01

    The interaction of a plasma with strong magnetic fields takes place in many laboratory experiments and astrophysical plasmas. Applying a strong magnetic field to the plasma may result in plasma displacement, magnetization, or the formation of instabilities. Important phenomena in plasma, such as the energy transport and the momentum balance, take a different form in each case. We study this interaction in a plasma that carries a short-duration (80-ns) current pulse, generating a magnetic field of up to 17 kG. The evolution of the magnetic field, plasma density, ion velocities, and electric fields are determined before and during the current pulse. The dependence of the plasma limiting current on the plasma density and composition are studied and compared to theoretical models based on the different phenomena. When the plasma collisionality is low, three typical velocities should be taken into consideration: the proton and heavier-ion Alfven velocities (v A p and v A h , respectively) and the EMHD magnetic-field penetration velocity into the plasma (v EMHD ). If both Alfven velocities are larger than v EMHD the plasma is pushed ahead of the magnetic piston and the magnetic field energy is dissipated into ion kinetic energy. If v EMHD is the largest of three velocities, the plasma become magnetized and the ions acquire a small axial momentum only. Different ion species may drift in different directions along the current lines. In this case, the magnetic field energy is probably dissipated into electron thermal energy. When vs > V EMHD > vi, as in the case of one of our experiments, ion mass separation occurs. The protons are pushed ahead of the piston while the heavier-ions become magnetized. Since the plasma electrons are unmagnetized they cannot cross the piston, and the heavy ions are probably charge-neutralized by electrons originating from the cathode that are 'born' magnetized

  18. Larmor time and proper time

    Energy Technology Data Exchange (ETDEWEB)

    Kudaka, Shoju [Department of Physics, University of the Ryukyus, Okinawa 903-0129 (Japan); Matsumoto, Shuichi, E-mail: shuichi@edu.u-ryukyu.ac.jp [Department of Mathematics, University of the Ryukyus, Okinawa 903-0129 (Japan)

    2012-10-01

    The idea of a Larmor clock is reexamined in the relativistic regime. We propose a concept of proper time for quantum theoretical particles. The Larmor clock can measure, under some relevant conditions, the proper time that passes while the particle stays in a space region. Our approach to Larmor clock is different than those of other researchers in the following two aspects: our concept of Larmor clock does not distinguish whether the particle is transmitted or reflected at the end of its stay, and pointer of our Larmor clock is not the spin but the total angular momentum. -- Highlights: ► The idea of a Larmor clock is reexamined in the relativistic regime. ► We propose a concept of proper time for quantum theoretical particles. ► The Larmor clock measures the passage of this quantum theoretical proper time.

  19. Extending Counter-streaming Motion from an Active Region Filament to a Sunspot Light Bridge

    Science.gov (United States)

    Wang, Haimin; Liu, Rui; Li, Qin; Liu, Chang; Deng, Na; Xu, Yan; Jing, Ju; Wang, Yuming; Cao, Wenda

    2018-01-01

    We analyze high-resolution observations from the 1.6 m telescope at Big Bear Solar Observatory that cover an active region filament. Counter-streaming motions are clearly observed in the filament. The northern end of the counter-streaming motions extends to a light bridge, forming a spectacular circulation pattern around a sunspot, with clockwise motion in the blue wing and counterclockwise motion in the red wing, as observed in the Hα off-bands. The apparent speed of the flow is around 10–60 km s‑1 in the filament, decreasing to 5–20 km s‑1 in the light bridge. The most intriguing results are the magnetic structure and the counter-streaming motions in the light bridge. Similar to those in the filament, the magnetic fields show a dominant transverse component in the light bridge. However, the filament is located between opposed magnetic polarities, while the light bridge is between strong fields of the same polarity. We analyze the power of oscillations with the image sequences of constructed Dopplergrams, and find that the filament’s counter-streaming motion is due to physical mass motion along fibrils, while the light bridge’s counter-streaming motion is due to oscillation in the direction along the line-of-sight. The oscillation power peaks around 4 minutes. However, the section of the light bridge next to the filament also contains a component of the extension of the filament in combination with the oscillation, indicating that some strands of the filament are extended to and rooted in that part of the light bridge.

  20. The motion of a classical particle with spin

    International Nuclear Information System (INIS)

    Amorim, R.

    1983-01-01

    A set equations of motion for a classical charged point particle with magnetic moment is proposed. These equations are obtained from a self-consistent variational principle and avoid the unphysical helicoidal motions characteristic of the theories that satisfy the condition S sup(μν) u sub(ν) = 0. The theories that satisfy the condiction S sup(μν) p sub(ν) = 0 are unified with the present theory in a trivial way. (Author) [pt

  1. Magnetic Resonance Imaging Assessment of Spinal Cord and Cauda Equina Motion in Supine Patients With Spinal Metastases Planned for Spine Stereotactic Body Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Chia-Lin [Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario (Canada); Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario (Canada); Sussman, Marshall S. [Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario (Canada); Atenafu, Eshetu G. [Department of Biostatistics, University Health Network, University of Toronto, Toronto, Ontario (Canada); Letourneau, Daniel [Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario (Canada); Ma, Lijun [Department of Radiation Oncology, University of California San Francisco, San Francisco, California (United States); Soliman, Hany; Thibault, Isabelle [Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario (Canada); Cho, B. C. John; Simeonov, Anna [Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario (Canada); Yu, Eugene [Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario (Canada); Fehlings, Michael G. [Department of Neurosurgery and Spine Program, Toronto Western Hospital, University of Toronto, Toronto, Ontario (Canada); Sahgal, Arjun, E-mail: arjun.sahgal@sunnybrook.ca [Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario (Canada); Department of Radiation Oncology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Ontario (Canada)

    2015-04-01

    Purpose: To assess motion of the spinal cord and cauda equina, which are critical neural tissues (CNT), which is important when evaluating the planning organ-at-risk margin required for stereotactic body radiation therapy. Methods and Materials: We analyzed CNT motion in 65 patients with spinal metastases (11 cervical, 39 thoracic, and 24 lumbar spinal segments) in the supine position using dynamic axial and sagittal magnetic resonance imaging (dMRI, 3T Verio, Siemens) over a 137-second interval. Motion was segregated according to physiologic cardiorespiratory oscillatory motion (characterized by the average root mean square deviation) and random bulk shifts associated with gross patient motion (characterized by the range). Displacement was evaluated in the anteroposterior (AP), lateral (LR), and superior-inferior (SI) directions by use of a correlation coefficient template matching algorithm, with quantification of random motion measure error over 3 separate trials. Statistical significance was defined according to P<.05. Results: In the AP, LR, and SI directions, significant oscillatory motion was observed in 39.2%, 35.1%, and 10.8% of spinal segments, respectively, and significant bulk motions in all cases. The median oscillatory CNT motions in the AP, LR, and SI directions were 0.16 mm, 0.17 mm, and 0.44 mm, respectively, and the maximal statistically significant oscillatory motions were 0.39 mm, 0.41 mm, and 0.77 mm, respectively. The median bulk displacements in the AP, LR, and SI directions were 0.51 mm, 0.59 mm, and 0.66 mm, and the maximal statistically significant displacements were 2.21 mm, 2.87 mm, and 3.90 mm, respectively. In the AP, LR, and SI directions, bulk displacements were greater than 1.5 mm in 5.4%, 9.0%, and 14.9% of spinal segments, respectively. No significant differences in axial motion were observed according to cord level or cauda equina. Conclusions: Oscillatory CNT motion was observed to be relatively minor. Our results

  2. Kinematic model of some types of motion of matter in active regions

    International Nuclear Information System (INIS)

    Platov, Yu.V.

    1983-01-01

    The kinematics of matter motion in variable magnetic fields of active regions on the Sun in the MHD approximation of a strong field and cold plasma is investigated. It is shown that the variation of sunspot magnetic moments lead to the development of different active phenomena in the solar atmosphere. The development of such phenomena at first can occur at the phase of active region growth, when new sunspots together with developed sunspots emerge in an active region or relative motions take place in a sunspot group

  3. Earthquake Ground Motion Measures for Seismic Response Evaluation of Structures

    Energy Technology Data Exchange (ETDEWEB)

    Cho, In-Kil; Ahn, Seong-Moon; Choun, Young-Sun; Seo, Jeong-Moon

    2007-03-15

    This study used the assessment results of failure criteria - base shear, story drift, top acceleration and top displacement - for a PSC containment building subjected to 30 sets of near-fault ground motions to evaluate the earthquake ground motion intensity measures. Seven intensity measures, peak ground acceleration(PGA), peak ground velocity(PGV), spectral acceleration(Sa), velocity(Sv), spectrum intensity for acceleration(SIa), velocity(SIv) and displacement(SId), were used to represent alternative ground motion. The regression analyses of the failure criteria for a PSC containment building were carried out to evaluate a proper intensity measure by using two regression models and seven ground motion parameters. The regression analysis results demonstrate the correlation coefficients of the failure criteria in terms of the candidate IM. From the results, spectral acceleration(Sa) is estimated as the best parameter for a evaluation of the structural safety for a seismic PSA.

  4. 7 CFR 29.112 - Proper light.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for correct...

  5. Study on optimization design of superconducting magnet for magnetic force assisted drug delivery system

    International Nuclear Information System (INIS)

    Fukui, S.; Abe, R.; Ogawa, J.; Oka, T.; Yamaguchi, M.; Sato, T.; Imaizumi, H.

    2007-01-01

    Analytical study on the design of the superconducting magnet for the magnetic force assisted drug delivery system is presented in this paper. The necessary magnetic field condition to reside the magnetic drug particle in the blood vessels is determined by analyzing the particle motion in the blood vessel. The design procedure of the superconducting magnet for the M-DDS is presented and some case studies are conducted. The analytical results show that the superconducting magnet to satisfy the magnetic field conduction for the M-DDS is practically feasible

  6. Numerical analysis of the motion of a suspended charged particle in multi-phase flow. Vol. 2

    Energy Technology Data Exchange (ETDEWEB)

    El-khalek, M M [Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt)

    1996-03-01

    The motion of a suspended charged particle in a two component viscous fluid through two infinite parallel plates was studied. The motion takes place under constant magnetic field normal to the plane of the motion. The effect of some parameters as particle volume, fluid density, viscosity of the fluid, and the magnetic force used on the motion were investigated. The particle is assumed moving initially from the midpoint of the channel with a velocity equal to the velocity of the fluid. The trajectory of solid spherical suspended charged particle is calculated by integrating the equations of motion of a single particle. The present simulation requires some empirical parameters concerning the collision of the particles with the wall. The differential equations of motion were numerically solved by Runge-Kutta method. Some conclusions about the path lines were deduced. 5 figs.

  7. Behaviour of a neutral particle with spin in an axial magnetic field

    International Nuclear Information System (INIS)

    Sorokin, S.V.; Ehpp, V.Ya.

    1982-01-01

    Proceeding from the Tamm-Good equation taking into account the spin influence on motion trajectory, the neutral particle motion tracjectory and vector turn of spin polarizition in axial magnetic field have been found. The behaviour of a neutral particle possessing its own magnetic moment in an axially-symmetric stationary magnetic field is considered

  8. Nonlinear dynamics of a magnetically driven Duffing-type spring–magnet oscillator in the static magnetic field of a coil

    International Nuclear Information System (INIS)

    Donoso, Guillermo; Ladera, Celso L

    2012-01-01

    We study the nonlinear oscillations of a forced and weakly dissipative spring–magnet system moving in the magnetic fields of two fixed coaxial, hollow induction coils. As the first coil is excited with a dc current, both a linear and a cubic magnet-position dependent force appear on the magnet–spring system. The second coil, located below the first, excited with an ac current, provides the oscillating magnetic driving force on the system. From the magnet–coil interactions, we obtain, analytically, the nonlinear motion equation of the system, found to be a forced and damped cubic Duffing oscillator moving in a quartic potential. The relative strengths of the coefficients of the motion equation can be easily set by varying the coils’ dc and ac currents. We demonstrate, theoretically and experimentally, the nonlinear behaviour of this oscillator, including its oscillation modes and nonlinear resonances, the fold-over effect, the hysteresis and amplitude jumps, and its chaotic behaviour. It is an oscillating system suitable for teaching an advanced experiment in nonlinear dynamics both at senior undergraduate and graduate levels. (paper)

  9. Using Simulated Ground Motions to Constrain Near-Source Ground Motion Prediction Equations in Areas Experiencing Induced Seismicity

    Science.gov (United States)

    Bydlon, S. A.; Dunham, E. M.

    2016-12-01

    Recent increases in seismic activity in historically quiescent areas such as Oklahoma, Texas, and Arkansas, including large, potentially induced events such as the 2011 Mw 5.6 Prague, OK, earthquake, have spurred the need for investigation into expected ground motions associated with these seismic sources. The neoteric nature of this seismicity increase corresponds to a scarcity of ground motion recordings within 50 km of earthquakes Mw 3.0 and greater, with increasing scarcity at larger magnitudes. Gathering additional near-source ground motion data will help better constraints on regional ground motion prediction equations (GMPEs) and will happen over time, but this leaves open the possibility of damaging earthquakes occurring before potential ground shaking and seismic hazard in these areas are properly understood. To aid the effort of constraining near-source GMPEs associated with induced seismicity, we integrate synthetic ground motion data from simulated earthquakes into the process. Using the dynamic rupture and seismic wave propagation code waveqlab3d, we perform verification and validation exercises intended to establish confidence in simulated ground motions for use in constraining GMPEs. We verify the accuracy of our ground motion simulator by performing the PEER/SCEC layer-over-halfspace comparison problem LOH.1 Validation exercises to ensure that we are synthesizing realistic ground motion data include comparisons to recorded ground motions for specific earthquakes in target areas of Oklahoma between Mw 3.0 and 4.0. Using a 3D velocity structure that includes a 1D structure with additional small-scale heterogeneity, the properties of which are based on well-log data from Oklahoma, we perform ground motion simulations of small (Mw 3.0 - 4.0) earthquakes using point moment tensor sources. We use the resulting synthetic ground motion data to develop GMPEs for small earthquakes in Oklahoma. Preliminary results indicate that ground motions can be amplified

  10. Criteria for saturated magnetization loop

    International Nuclear Information System (INIS)

    Harres, A.; Mikhov, M.; Skumryev, V.; Andrade, A.M.H. de; Schmidt, J.E.; Geshev, J.

    2016-01-01

    Proper estimation of magnetization curve parameters is vital in studying magnetic systems. In the present article, criteria for discrimination non-saturated (minor) from saturated (major) hysteresis loops are proposed. These employ the analysis of (i) derivatives of both ascending and descending branches of the loop, (ii) remanent magnetization curves, and (iii) thermomagnetic curves. Computational simulations are used in order to demonstrate their validity. Examples illustrating the applicability of these criteria to well-known real systems, namely Fe_3O_4 and Ni fine particles, are provided. We demonstrate that the anisotropy-field value estimated from a visual examination of an only apparently major hysteresis loop could be more than two times lower than the real one. - Highlights: • Proper estimation of hysteresis-loop parameters is vital in magnetic studies. • We propose criteria for discrimination minor from major hysteresis loops. • The criteria analyze magnetization, remanence and ZFC/FC curves and/or their derivatives. • Examples of their application on real nanoparticles systems are given. • Using the criteria could avoid twofold or bigger saturation-field underestimation errors.

  11. Criteria for saturated magnetization loop

    Energy Technology Data Exchange (ETDEWEB)

    Harres, A. [Departamento de Física, UFSM, Santa Maria, 97105-900 Rio Grande do Sul (Brazil); Mikhov, M. [Faculty of Physics, University of Sofia, 1164 Sofia (Bulgaria); Skumryev, V. [Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona (Spain); Departament de Física, Universitat Autònoma de Barcelona, 08193 Barcelona (Spain); Andrade, A.M.H. de; Schmidt, J.E. [Instituto de Física, UFRGS, Porto Alegre, 91501-970 Rio Grande do Sul (Brazil); Geshev, J., E-mail: julian@if.ufrgs.br [Departament de Física, Universitat Autònoma de Barcelona, 08193 Barcelona (Spain); Instituto de Física, UFRGS, Porto Alegre, 91501-970 Rio Grande do Sul (Brazil)

    2016-03-15

    Proper estimation of magnetization curve parameters is vital in studying magnetic systems. In the present article, criteria for discrimination non-saturated (minor) from saturated (major) hysteresis loops are proposed. These employ the analysis of (i) derivatives of both ascending and descending branches of the loop, (ii) remanent magnetization curves, and (iii) thermomagnetic curves. Computational simulations are used in order to demonstrate their validity. Examples illustrating the applicability of these criteria to well-known real systems, namely Fe{sub 3}O{sub 4} and Ni fine particles, are provided. We demonstrate that the anisotropy-field value estimated from a visual examination of an only apparently major hysteresis loop could be more than two times lower than the real one. - Highlights: • Proper estimation of hysteresis-loop parameters is vital in magnetic studies. • We propose criteria for discrimination minor from major hysteresis loops. • The criteria analyze magnetization, remanence and ZFC/FC curves and/or their derivatives. • Examples of their application on real nanoparticles systems are given. • Using the criteria could avoid twofold or bigger saturation-field underestimation errors.

  12. Turbulence, transport and confinement: from tokamaks to star magnetism

    International Nuclear Information System (INIS)

    Strugarek, Antoine

    2012-01-01

    This thesis is part of the general study of self-organization in hot and magnetized plasmas. We focus our work on two specific objects: stars and tokamaks. We use first principle numerical simulations to study turbulence, transport and confinement in these plasmas. The first part of this thesis introduces the main characteristics of stellar and tokamak plasmas. The reasons for studying them together are properly detailed. The second part is focused on stellar aspects. We study the interactions between the 3D turbulent motions in the solar convection zone with an internal magnetic field in the tachocline (the transition region between the instable and stable zones in the Sun). The tachocline is a very thin layer (less than five percent of the solar radius) that acts as a transport barrier of angular momentum. We show that such an internal magnetic field is not likely to explain the observed thickness of the tachocline and we give some insights on how to find alternative mechanisms to constrain it. We also explore the effect of the environment of star on its structure. We develop a methodology to study the influence of stellar wind and of the magnetic coupling of a star with its orbiting planets. We use the same methodology to analyse the magnetic interaction between a stellar wind and a planetary magnetosphere that acts as a transport barrier of matter. Then, the third part is dedicated to fusion oriented research. We present a numerical investigation on the experimental mechanisms that lead to the development of transport barriers in the plasma. These barriers are particularly important for the design of high performance fusion devices. The creation of transport barriers is obtained in turbulent first principle simulations for the very first time. The collaboration between the two scientific teams lead to the results presented in the fourth part of this thesis. An original spectral method is developed to analyse the saturation of stellar convective dynamos and of

  13. Pitch Motion Stabilization by Propeller Speed Control Using Statistical Controller Design

    DEFF Research Database (Denmark)

    Nakatani, Toshihiko; Blanke, Mogens; Galeazzi, Roberto

    2006-01-01

    This paper describes dynamics analysis of a small training boat and a possibility of ship pitch stabilization by control of propeller speed. After upgrading the navigational system of an actual small training boat, in order to identify the model of the ship, the real data collected by sea trials...... were used for statistical analysis and system identification. This analysis shows that the pitching motion is indeed influenced by engine speed and it is suggested that there exists a possibility of reducing the pitching motion by properly controlling the engine throttle. Based on this observation...

  14. Magnetic study of iron-containing carbon nanotubes: Feasibility for magnetic hyperthermia

    Energy Technology Data Exchange (ETDEWEB)

    Krupskaya, Y. [Leibniz-Institute for Solid State and Materials Research IFW Dresden, 01171 Dresden (Germany)], E-mail: y.krupskaya@ifw-dresden.de; Mahn, C.; Parameswaran, A. [Leibniz-Institute for Solid State and Materials Research IFW Dresden, 01171 Dresden (Germany); Taylor, A.; Kraemer, K. [Department of Urology, Dresden University of Technology, 01307 Dresden (Germany); Hampel, S.; Leonhardt, A.; Ritschel, M.; Buechner, B.; Klingeler, R. [Leibniz-Institute for Solid State and Materials Research IFW Dresden, 01171 Dresden (Germany)

    2009-12-15

    We present a detailed magnetic study of iron containing carbon nanotubes (Fe-CNT), which highlights their potential for contactless magnetic heating in hyperthermia cancer treatment. Magnetic field dependent AC inductive heating experiments on Fe-CNT dispersions show a substantial temperature increase of Fe-CNT dispersions in applied AC magnetic fields. DC and AC magnetization studies have been done in order to elucidate the heating mechanism. We observe a different magnetic response of Fe-CNT powder compared to Fe-CNT dispersed in aqueous solution, e.g., ferromagnetic Fe-CNT in powder do not show any hysteresis when being dispersed in liquid. Our data indicate the motion of Fe-CNT in liquid in applied magnetic fields.

  15. Markerless 3D Head Tracking for Motion Correction in High Resolution PET Brain Imaging

    DEFF Research Database (Denmark)

    Olesen, Oline Vinter

    relying on markers. Data-driven motion correction is problematic due to the physiological dynamics. Marker-based tracking is potentially unreliable, and it is extremely hard to validate when the tracking information is correct. The motion estimation is essential for proper motion correction of the PET......This thesis concerns application specific 3D head tracking. The purpose is to improve motion correction in position emission tomography (PET) brain imaging through development of markerless tracking. Currently, motion correction strategies are based on either the PET data itself or tracking devices...... images. Incorrect motion correction can in the worst cases result in wrong diagnosis or treatment. The evolution of a markerless custom-made structured light 3D surface tracking system is presented. The system is targeted at state-of-the-art high resolution dedicated brain PET scanners with a resolution...

  16. Ages of the Bulge Globular Clusters NGC 6522 and NGC 6626 (M28) from HST Proper-motion-cleaned Color–Magnitude Diagrams

    Science.gov (United States)

    Kerber, L. O.; Nardiello, D.; Ortolani, S.; Barbuy, B.; Bica, E.; Cassisi, S.; Libralato, M.; Vieira, R. G.

    2018-01-01

    Bulge globular clusters (GCs) with metallicities [Fe/H] ≲ ‑1.0 and blue horizontal branches are candidates to harbor the oldest populations in the Galaxy. Based on the analysis of HST proper-motion-cleaned color–magnitude diagrams in filters F435W and F625W, we determine physical parameters for the old bulge GCs NGC 6522 and NGC 6626 (M28), both with well-defined blue horizontal branches. We compare these results with similar data for the inner halo cluster NGC 6362. These clusters have similar metallicities (‑1.3 ≤ [Fe/H] ≤ ‑1.0) obtained from high-resolution spectroscopy. We derive ages, distance moduli, and reddening values by means of statistical comparisons between observed and synthetic fiducial lines employing likelihood statistics and the Markov chain Monte Carlo method. The synthetic fiducial lines were generated using α-enhanced BaSTI and Dartmouth stellar evolutionary models, adopting both canonical (Y ∼ 0.25) and enhanced (Y ∼ 0.30–0.33) helium abundances. RR Lyrae stars were employed to determine the HB magnitude level, providing an independent indicator to constrain the apparent distance modulus and the helium enhancement. The shape of the observed fiducial line could be compatible with some helium enhancement for NGC 6522 and NGC 6626, but the average magnitudes of RR Lyrae stars tend to rule out this hypothesis. Assuming canonical helium abundances, BaSTI and Dartmouth models indicate that all three clusters are coeval, with ages between ∼12.5 and 13.0 Gyr. The present study also reveals that NGC 6522 has at least two stellar populations, since its CMD shows a significantly wide subgiant branch compatible with 14% ± 2% and 86% ± 5% for first and second generations, respectively. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute.

  17. Proper Acknowledgment?

    Science.gov (United States)

    East, Julianne

    2005-01-01

    The concern in Australian universities about the prevalence of plagiarism has led to the development of policies about academic integrity and in turn focused attention on the need to inform students about how to avoid plagiarism and how to properly acknowledge. Teaching students how to avoid plagiarism can appear to be straightforward if based on…

  18. Electromechanical motion devices

    CERN Document Server

    Krause, Paul C; Pekarek, Steven D

    2012-01-01

    This text provides a basic treatment of modern electric machine analysis that gives readers the necessary background for comprehending the traditional applications and operating characteristics of electric machines-as well as their emerging applications in modern power systems and electric drives, such as those used in hybrid and electric vehicles. Through the appropriate use of reference frame theory, Electromagnetic Motion Devices, Second Edition introduces readers to field-oriented control of induction machines, constant-torque, and constant-power control of dc, permanent-magnet ac

  19. Domain wall motions in perpendicularly magnetized CoFe/Pd multilayer nanowire

    DEFF Research Database (Denmark)

    Meng, Zhaoliang; Kumar, Manoj; Qiu, Jinjun

    2014-01-01

    Current-induced domain wall (DW) motion is investigated in a 600nm wide nanowire using multilayer film with a structure of Ta(5nm)/Pd(5nm)/[CoFe(0.4nm)/Pd(1.2nm)]15/Ta(5nm) in terms of anomalous Hall effect measurements. It is found that motion of DWs can be driven by a current density as low as 1...

  20. Gamma-stability and vortex motion in type II superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kurzke, Matthias; Spirn, Daniel

    2009-07-15

    We consider a time-dependent Ginzburg-Landau equation for superconductors with a strictly complex relaxation parameter, and derive motion laws for the vortices in the case of a finite number of vortices in a bounded magnetic field. The motion laws correspond to the flux-flow Hall effect. As our main tool, we develop a quantitative {gamma}-stability result relating the Ginzburg-Landau energy to the renormalized energy. (orig.)

  1. Gamma-stability and vortex motion in type II superconductors

    International Nuclear Information System (INIS)

    Kurzke, Matthias; Spirn, Daniel

    2009-01-01

    We consider a time-dependent Ginzburg-Landau equation for superconductors with a strictly complex relaxation parameter, and derive motion laws for the vortices in the case of a finite number of vortices in a bounded magnetic field. The motion laws correspond to the flux-flow Hall effect. As our main tool, we develop a quantitative Γ-stability result relating the Ginzburg-Landau energy to the renormalized energy. (orig.)

  2. The magnetic universe geophysical and astrophysical dynamo theory

    CERN Document Server

    Rüdiger, Günther

    2004-01-01

    Magnetism is one of the most pervasive features of the Universe, with planets, stars and entire galaxies all having associated magnetic fields. All of these fields are generated by the motion of electrically conducting fluids, the so-called dynamo effect. The precise details of what drives the motion, and indeed what the fluid consists of, differ widely though. In this work the authors draw upon their expertise in geophysical and astrophysical MHD to explore some of these phenomena, and describe the similarities and differences between different magnetized objects. They also explain why magn

  3. Macroscopic spin-orbit coupling in non-uniform magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Tabat, N.; Edelman, H. S.; Song, D. [Semaphore Scientific, Inc., St. Cloud, Minnesota 56301 (United States); Vogt, T. [Department of Electrical and Computer Engineering, St. Cloud State University, St. Cloud, Minnesota 56301 (United States)

    2015-03-02

    Translational dynamics of aggregated magnetic nano-particles placed in a rotating external magnetic field is described. It is observed and explained that aggregates that spin within a radially decreasing field strength must execute an orbital motion of their center of mass in a sense that counters their spin rotation. This orbital motion is tightly coupled to the spin dynamics of the aggregates. An analytical model for the canonical variables describing the orbital motion is derived and shown to be in good agreement with the measured values.

  4. Macroscopic spin-orbit coupling in non-uniform magnetic fields

    International Nuclear Information System (INIS)

    Tabat, N.; Edelman, H. S.; Song, D.; Vogt, T.

    2015-01-01

    Translational dynamics of aggregated magnetic nano-particles placed in a rotating external magnetic field is described. It is observed and explained that aggregates that spin within a radially decreasing field strength must execute an orbital motion of their center of mass in a sense that counters their spin rotation. This orbital motion is tightly coupled to the spin dynamics of the aggregates. An analytical model for the canonical variables describing the orbital motion is derived and shown to be in good agreement with the measured values

  5. Dynamics of a rarefied plasma in a magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sagdeyev, R S; Kadomtsev, B B; Rudakov, L I; Vedyonov, A A

    1958-07-01

    The nature of the motion and properties of high temperature plasma in a magnetic field is of particular interest for the problem of producing controlled thermonuclear reactions. The most general theoretical approach to such problems lies in the description of the plasma by the Boltzmann and Maxwell equations that connect the self-consistent electric and magnetic fields with the ion and electron distribution functions. The exact equations for the motion of plasma in an electromagnetic field can only be solved in certain simple cases especially because the fields are influenced by the collective motion of all the particles. For a certain class of problems it is possible to work out a procedure for decreasing the number of variables and thus simplify the characteristic equations. In this work the following cases are considered and equations derived: equations for the macroscopic motion of the plasma; hydrodynamics of a low pressure plasma; instability of plasma in a magnetic field with an anisotropic ion velocity distribution; stability of a pinched cylindrical plasma using the kinetic equation; non-linear one-dimensional motion of a rarefied plasma.

  6. Self-motion perception: assessment by real-time computer-generated animations

    Science.gov (United States)

    Parker, D. E.; Phillips, J. O.

    2001-01-01

    We report a new procedure for assessing complex self-motion perception. In three experiments, subjects manipulated a 6 degree-of-freedom magnetic-field tracker which controlled the motion of a virtual avatar so that its motion corresponded to the subjects' perceived self-motion. The real-time animation created by this procedure was stored using a virtual video recorder for subsequent analysis. Combined real and illusory self-motion and vestibulo-ocular reflex eye movements were evoked by cross-coupled angular accelerations produced by roll and pitch head movements during passive yaw rotation in a chair. Contrary to previous reports, illusory self-motion did not correspond to expectations based on semicircular canal stimulation. Illusory pitch head-motion directions were as predicted for only 37% of trials; whereas, slow-phase eye movements were in the predicted direction for 98% of the trials. The real-time computer-generated animations procedure permits use of naive, untrained subjects who lack a vocabulary for reporting motion perception and is applicable to basic self-motion perception studies, evaluation of motion simulators, assessment of balance disorders and so on.

  7. On the swimming motion of spheroidal magnetotactic bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Cui Zhen; Kong Dali; Zhang Keke [Department of Mathematical Sciences, University of Exeter, Exeter EX4 4QF (United Kingdom); Pan Yongxin, E-mail: kzhang@ex.ac.uk [Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing (China)

    2012-10-15

    We investigate, via both theoretical and experimental methods, the swimming motion of magnetotactic bacteria having the shape of an elongated prolate spheroid in a viscous liquid under the influence of an imposed magnetic field. A fully three-dimensional Stokes flow, driven by the translation and rotation of a swimming bacterium, exerts a complicated viscous drag/torque on the motion of a non-spherical bacterium. By assuming that the body of the bacterium is non-deformable and that the interaction between different bacteria is weak and hence negligible, we have derived a system of 12 coupled nonlinear ordinary differential equations that govern both the motion and the orientation of a swimming spheroidal magnetotactic bacterium. The focus of the study is on how the shape of a non-spherical magnetotactic bacterium, marked by the size of its eccentricity, affects the pattern of its swimming motion. It is revealed that the pattern/speed of a swimming spheroidal magnetotactic bacterium is highly sensitive not only to the direction of its magnetic moment but also to its shape. We also compare the theoretical pattern obtained from the solutions of the 12 coupled differential equations with that observed in the laboratory experiments using the magnetotactic bacteria found in Lake Miyun near Beijing, China, showing that the observed pattern can be largely reproduced with an appropriate set of parameters in our theoretical model. (paper)

  8. On the swimming motion of spheroidal magnetotactic bacteria

    International Nuclear Information System (INIS)

    Cui Zhen; Kong Dali; Zhang Keke; Pan Yongxin

    2012-01-01

    We investigate, via both theoretical and experimental methods, the swimming motion of magnetotactic bacteria having the shape of an elongated prolate spheroid in a viscous liquid under the influence of an imposed magnetic field. A fully three-dimensional Stokes flow, driven by the translation and rotation of a swimming bacterium, exerts a complicated viscous drag/torque on the motion of a non-spherical bacterium. By assuming that the body of the bacterium is non-deformable and that the interaction between different bacteria is weak and hence negligible, we have derived a system of 12 coupled nonlinear ordinary differential equations that govern both the motion and the orientation of a swimming spheroidal magnetotactic bacterium. The focus of the study is on how the shape of a non-spherical magnetotactic bacterium, marked by the size of its eccentricity, affects the pattern of its swimming motion. It is revealed that the pattern/speed of a swimming spheroidal magnetotactic bacterium is highly sensitive not only to the direction of its magnetic moment but also to its shape. We also compare the theoretical pattern obtained from the solutions of the 12 coupled differential equations with that observed in the laboratory experiments using the magnetotactic bacteria found in Lake Miyun near Beijing, China, showing that the observed pattern can be largely reproduced with an appropriate set of parameters in our theoretical model. (paper)

  9. Implied motion because of instability in Hokusai Manga activates the human motion-sensitive extrastriate visual cortex: an fMRI study of the impact of visual art.

    Science.gov (United States)

    Osaka, Naoyuki; Matsuyoshi, Daisuke; Ikeda, Takashi; Osaka, Mariko

    2010-03-10

    The recent development of cognitive neuroscience has invited inference about the neurosensory events underlying the experience of visual arts involving implied motion. We report functional magnetic resonance imaging study demonstrating activation of the human extrastriate motion-sensitive cortex by static images showing implied motion because of instability. We used static line-drawing cartoons of humans by Hokusai Katsushika (called 'Hokusai Manga'), an outstanding Japanese cartoonist as well as famous Ukiyoe artist. We found 'Hokusai Manga' with implied motion by depicting human bodies that are engaged in challenging tonic posture significantly activated the motion-sensitive visual cortex including MT+ in the human extrastriate cortex, while an illustration that does not imply motion, for either humans or objects, did not activate these areas under the same tasks. We conclude that motion-sensitive extrastriate cortex would be a critical region for perception of implied motion in instability.

  10. Electric-magnetic duality as a secondary symmetry

    International Nuclear Information System (INIS)

    Brandt, R.A.; Young, K.

    1980-01-01

    In both the abelian and non-abelian classical point magnetic monopole theories, electric current conservation is a consequence of gauge invariance, but, since there is no magnetic gauge group, magnetic current conservation is not a Noether-type conservation law. In the abelian models, the equations of motion (but not the lagrangian) are invariant to the duality rotations in electric-magnetic charge space, but this is not the case in the non-abelian models. In an attempt to understand these and related points, we introduce a generalization of Noether's theorem. Consider a physical system described by a set of variables THETA and characterized by a lagrangian density L(THETA). A transormation law THETA → G THETA which leaves L invariant leads to a conserved current Jsub(μ)(THETA). We then call G a primary symmetry. A second transformation law THETA → D THETA which leaves the equations of motion, but not L, invariant then leads to another conserved current Jsub(μ)(D THETA). We then call D a secondary symmetra. Our main point is that Jsub(μ) (D THETA) may be conserved even if the equations of motion are not invariant under D. All that is required is that the change of the equations of motion under D is perpendicular (in the field space) to the change of the fields under G. Then we call D an incomplete secondary symmetry. We show that in both the abelian and non-abelian monopole theories, duality is an incomplete secondary symmetry whose associated conservation law is magnetic current conservation. Thus it is the interpretation of duality as a secondary symmetry which explains magnetic current conservation and which generalizes from the abelian theories to the non-abelian ones. This suggests that magnetic current conservation may remain valid in quantum field theory. (orig.)

  11. Large amplitude oscillatory motion along a solar filament

    Science.gov (United States)

    Vršnak, B.; Veronig, A. M.; Thalmann, J. K.; Žic, T.

    2007-08-01

    Context: Large amplitude oscillations of solar filaments is a phenomenon that has been known for more than half a century. Recently, a new mode of oscillations, characterized by periodical plasma motions along the filament axis, was discovered. Aims: We analyze such an event, recorded on 23 January 2002 in Big Bear Solar Observatory Hα filtergrams, to infer the triggering mechanism and the nature of the restoring force. Methods: Motion along the filament axis of a distinct buldge-like feature was traced, to quantify the kinematics of the oscillatory motion. The data were fitted by a damped sine function to estimate the basic parameters of the oscillations. To identify the triggering mechanism, morphological changes in the vicinity of the filament were analyzed. Results: The observed oscillations of the plasma along the filament were characterized by an initial displacement of 24 Mm, an initial velocity amplitude of 51 km s-1, a period of 50 min, and a damping time of 115 min. We interpret the trigger in terms of poloidal magnetic flux injection by magnetic reconnection at one of the filament legs. The restoring force is caused by the magnetic pressure gradient along the filament axis. The period of oscillations, derived from the linearized equation of motion (harmonic oscillator) can be expressed as P=π√{2}L/v_Aϕ≈4.4L/v_Aϕ, where v_Aϕ =Bϕ0/√μ_0ρ represents the Alfvén speed based on the equilibrium poloidal field Bϕ0. Conclusions: Combination of our measurements with some previous observations of the same kind of oscillations shows good agreement with the proposed interpretation. Movie to Fig. 1 is only available in electronic form at http://www.aanda.org

  12. Domain wall motion in magnetically frustrated nanorings

    Science.gov (United States)

    Lubarda, M. V.; Escobar, M. A.; Li, S.; Chang, R.; Fullerton, E. E.; Lomakin, V.

    2012-06-01

    We describe a magnetically frustrated nanoring (MFNR) configuration which is formed by introducing antiferromagnetic coupling across an interface orthogonal to the ring's circumferential direction. Such structures have the unique characteristic that only one itinerant domain wall (DW) can exist in the ring, which does not need to be nucleated or injected into the structure and can never escape making it analogous to a magnetic Möbius strip. Numerical simulations show that the DW in a MFNR can be driven consecutively around the ring with a prescribed cyclicity, and that the frequency of revolutions can be controlled by the applied field. The energy landscapes can be controlled to be flat allowing for low fields of operation or to have a barrier for thermal stability. Potential logic and memory applications of MFNRs are considered and discussed.

  13. Apparent diffusion coefficient measurement in a moving phantom simulating linear respiratory motion.

    Science.gov (United States)

    Kwee, Thomas C; Takahara, Taro; Muro, Isao; Van Cauteren, Marc; Imai, Yutaka; Nievelstein, Rutger A J; Mali, Willem P T M; Luijten, Peter R

    2010-10-01

    The aim of this study was to examine the effect of simulated linear respiratory motion on apparent diffusion coefficient (ADC) measurements. Six rectangular test tubes (14 × 92 mm) filled with either water, tomato ketchup, or mayonnaise were positioned in a box containing agarose gel. This box was connected to a double-acting pneumatic cylinder, capable of inducing periodic linear motion in the long-axis direction of the magnetic bore (23-mm stroke). Diffusion-weighted magnetic resonance imaging was performed for both the static and moving phantoms, and ADC measurements were made in the six test tubes in both situations. In the three test tubes whose long axes were parallel to the direction of motion, ADCs agreed well between the moving and static phantom situations. However, in two test tubes that were filled with fluids that had a considerably lower diffusion coefficient than the surrounding agarose gel, and whose long axes were perpendicular to the direction of motion, the ADCs agreed poorly between the moving and static phantom situations. ADC measurements of large homogeneous structures are not affected by linear respiratory motion. However, ADC measurements of inhomogeneous or small structures are affected by linear respiratory motion due to partial volume effects.

  14. Apparent diffusion coefficient measurement in a moving phantom simulating linear respiratory motion

    International Nuclear Information System (INIS)

    Kwee, T.C.; Takahara, Taro; Nievelstein, R.A.J.; Mali, W.P.T.M.; Luijten, P.R.; Muro, Isao; Imai, Yutaka; Cauteren, M. Van

    2010-01-01

    The aim of this study was to examine the effect of simulated linear respiratory motion on apparent diffusion coefficient (ADC) measurements. Six rectangular test tubes (14 x 92 mm) filled with either water, tomato ketchup, or mayonnaise were positioned in a box containing agarose gel. This box was connected to a double-acting pneumatic cylinder, capable of inducing periodic linear motion in the long-axis direction of the magnetic bore (23-mm stroke). Diffusion-weighted magnetic resonance imaging was performed for both the static and moving phantoms, and ADC measurements were made in the six test tubes in both situations. In the three test tubes whose long axes were parallel to the direction of motion, ADCs agreed well between the moving and static phantom situations. However, in two test tubes that were filled with fluids that had a considerably lower diffusion coefficient than the surrounding agarose gel, and whose long axes were perpendicular to the direction of motion, the ADCs agreed poorly between the moving and static phantom situations. ADC measurements of large homogeneous structures are not affected by linear respiratory motion. However, ADC measurements of inhomogeneous or small structures are affected by linear respiratory motion due to partial volume effects. (author)

  15. Motion Control of Urea-Powered Biocompatible Hollow Microcapsules.

    Science.gov (United States)

    Ma, Xing; Wang, Xu; Hahn, Kersten; Sánchez, Samuel

    2016-03-22

    The quest for biocompatible microswimmers powered by compatible fuel and with full motion control over their self-propulsion is a long-standing challenge in the field of active matter and microrobotics. Here, we present an active hybrid microcapsule motor based on Janus hollow mesoporous silica microparticles powered by the biocatalytic decomposition of urea at physiological concentrations. The directional self-propelled motion lasts longer than 10 min with an average velocity of up to 5 body lengths per second. Additionally, we control the velocity of the micromotor by chemically inhibiting and reactivating the enzymatic activity of urease. The incorporation of magnetic material within the Janus structure provides remote magnetic control on the movement direction. Furthermore, the mesoporous/hollow structure can load both small molecules and larger particles up to hundreds of nanometers, making the hybrid micromotor an active and controllable drug delivery microsystem.

  16. An embedded optical tracking system for motion-corrected magnetic resonance imaging at 7T.

    Science.gov (United States)

    Schulz, Jessica; Siegert, Thomas; Reimer, Enrico; Labadie, Christian; Maclaren, Julian; Herbst, Michael; Zaitsev, Maxim; Turner, Robert

    2012-12-01

    Prospective motion correction using data from optical tracking systems has been previously shown to reduce motion artifacts in MR imaging of the head. We evaluate a novel optical embedded tracking system. The home-built optical embedded tracking system performs image processing within a 7 T scanner bore, enabling high speed tracking. Corrected and uncorrected in vivo MR volumes are acquired interleaved using a modified 3D FLASH sequence, and their image quality is assessed and compared. The latency between motion and correction of the slice position was measured to be (19 ± 5) ms, and the tracking noise has a standard deviation no greater than 10 μm/0.005° during conventional MR scanning. Prospective motion correction improved the edge strength by 16 % on average, even though the volunteers were asked to remain motionless during the acquisitions. Using a novel method for validating the effectiveness of in vivo prospective motion correction, we have demonstrated that prospective motion correction using motion data from the embedded tracking system considerably improved image quality.

  17. Magnetohydrodynamic interpretation of the motion of prominences

    International Nuclear Information System (INIS)

    Sakurai, Takashi

    1976-01-01

    We study three types of prominence eruptions, which we will call the arch type, the loop type, and the gigantic arch type, respectively, from their shapes. If we regard the prominence as a magnetic flux tube, the onset of its ascending motion can be interpreted as the motion due to the screw-mode instability, which is the most unstable mode of instabilities of a magnetofluid column (pinch). The growth rate of this mode is evaluated and is shown to be consistent with the time scale of the initial stage of the eruption. In order to study the nonlinear stage of the instability, we propose a method of numerical calculation based on a variational technique known as Ritz's method. The result shows that the characteristic motion of the arch-, loop-, and gigantic arch-type eruptions may be reproduced by perturbing a model sequence with decreasing pitch angles of the unperturbed helical magnetic field lines. This conclusion seems to be supported by the pitch angles of observed threads in each type of prominence and also by the fact that the observed time profiles of the rising velocity of the prominences of each type agree well with those predicted from model calculations. (auth.)

  18. Spinal cord motion. Influence of respiration and cardiac cycle

    Energy Technology Data Exchange (ETDEWEB)

    Winklhofer, S. [RWTH Aachen University Hospital (Germany). Dept. of Neuroradiology; University Hospital Zurich (Switzerland). Inst. of Diagnostic and Interventional Radiology; Schoth, F. [RWTH Aachen University Hospital (Germany). Dept. of Diagnostic Radiology; Stolzmann, P. [University Hospital Zurich (Switzerland). Inst. of Diagnostic and Interventional Radiology; Krings, T. [Toronto Western Hospital, ON (Canada). Div. of Neuroradiology; Mull, M.; Wiesmann, M. [RWTH Aachen University Hospital (Germany). Dept. of Neuroradiology; Stracke, C.P. [RWTH Aachen University Hospital (Germany). Dept. of Neuroradiology; Alfried-Krupp-Hospital, Essen (Germany). Dept. of Neuroradiology

    2014-11-15

    To assess physiological spinal cord motion during the cardiac cycle compared with the influence of respiration based on magnetic resonance imaging (MRI) measurements. Anterior-posterior spinal cord motion within the spinal canal was assessed in 16 healthy volunteers (median age, 25 years) by cardiac-triggered and cardiac-gated gradient echo pulse sequence MRI. Image acquisition was performed during breath-holding, normal breathing, and forced breathing. Normal spinal cord motion values were computed using descriptive statistics. Breathing-dependent differences were assessed using the Wilcoxon signed-rank test and compared with the cardiac-based cord motion. A normal value table was set up for the spinal cord motion of each vertebral cervico-thoracic-lumbar segment. Significant differences in cord motion were found between cardiac-based motion while breath-holding and the two breathing modalities (P < 0.01 each). Spinal cord motion was found to be highest during forced breathing, with a maximum in the lower cervical spinal segments (C5; mean, 2.1 mm ± 1.17). Image acquisition during breath-holding revealed the lowest motion. MRI permits the demonstration and evaluation of cardiac and respiration-dependent spinal cord motion within the spinal canal from the cervical to lumbar segments. Breathing conditions have a considerably greater impact than cardiac activity on spinal cord motion.

  19. Spinal cord motion. Influence of respiration and cardiac cycle

    International Nuclear Information System (INIS)

    Winklhofer, S.; University Hospital Zurich; Schoth, F.; Stolzmann, P.; Krings, T.; Mull, M.; Wiesmann, M.; Stracke, C.P.; Alfried-Krupp-Hospital, Essen

    2014-01-01

    To assess physiological spinal cord motion during the cardiac cycle compared with the influence of respiration based on magnetic resonance imaging (MRI) measurements. Anterior-posterior spinal cord motion within the spinal canal was assessed in 16 healthy volunteers (median age, 25 years) by cardiac-triggered and cardiac-gated gradient echo pulse sequence MRI. Image acquisition was performed during breath-holding, normal breathing, and forced breathing. Normal spinal cord motion values were computed using descriptive statistics. Breathing-dependent differences were assessed using the Wilcoxon signed-rank test and compared with the cardiac-based cord motion. A normal value table was set up for the spinal cord motion of each vertebral cervico-thoracic-lumbar segment. Significant differences in cord motion were found between cardiac-based motion while breath-holding and the two breathing modalities (P < 0.01 each). Spinal cord motion was found to be highest during forced breathing, with a maximum in the lower cervical spinal segments (C5; mean, 2.1 mm ± 1.17). Image acquisition during breath-holding revealed the lowest motion. MRI permits the demonstration and evaluation of cardiac and respiration-dependent spinal cord motion within the spinal canal from the cervical to lumbar segments. Breathing conditions have a considerably greater impact than cardiac activity on spinal cord motion.

  20. On the motion of the field of a permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Leus, Vladimir [Sobolev Institute of Mathematics, Novosibirsk (Russian Federation); Taylor, Stephen, E-mail: s.taylor@liv.ac.uk [Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool L69 3GJ (United Kingdom)

    2011-09-15

    A description is given of a series of recent experiments using a rotating magnetic circuit comprising a permanent magnet ring and yoke, and a stationary conductor in the air gap between the ring and yoke. The EMF induced in this case cannot be described by a simple application of Faraday's flux law. This is because the magnetic flux in the air gap and the area of the gap both remain constant. The experimental results are best explained by the fact that the magnetic field itself rotates with the rotating magnet. This is controversial in the scientific and educational literature, as shown by citations from various authors (e.g. Feynman, Tamm and Landau all disagree, and with each other). However, these experiments, which may be readily reproduced, do in fact settle the question.

  1. Oil Motion Control by an Extra Pinning Structure in Electro-Fluidic Display.

    Science.gov (United States)

    Dou, Yingying; Tang, Biao; Groenewold, Jan; Li, Fahong; Yue, Qiao; Zhou, Rui; Li, Hui; Shui, Lingling; Henzen, Alex; Zhou, Guofu

    2018-04-06

    Oil motion control is the key for the optical performance of electro-fluidic displays (EFD). In this paper, we introduced an extra pinning structure (EPS) into the EFD pixel to control the oil motion inside for the first time. The pinning structure canbe fabricated together with the pixel wall by a one-step lithography process. The effect of the relative location of the EPS in pixels on the oil motion was studied by a series of optoelectronic measurements. EPS showed good control of oil rupture position. The properly located EPS effectively guided the oil contraction direction, significantly accelerated switching on process, and suppressed oil overflow, without declining in aperture ratio. An asymmetrically designed EPS off the diagonal is recommended. This study provides a novel and facile way for oil motion control within an EFD pixel in both direction and timescale.

  2. Particles trajectories in magnetic filaments

    Energy Technology Data Exchange (ETDEWEB)

    Bret, A. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain); Instituto de Investigaciones Energéticas y Aplicaciones Industriales, Campus Universitario de Ciudad Real, 13071 Ciudad Real (Spain)

    2015-07-15

    The motion of a particle in a spatially harmonic magnetic field is a basic problem involved, for example, in the mechanism of formation of a collisionless shock. In such settings, it is generally reasoned that particles entering a Weibel generated turbulence are trapped inside it, provided their Larmor radius in the peak field is smaller than the field coherence length. The goal of this work is to put this heuristic conclusion on firm ground by studying, both analytically and numerically, such motion. A toy model is analyzed, consisting of a relativistic particle entering a region of space occupied by a spatially harmonic field. The particle penetrates the magnetic structure in a direction aligned with the magnetic filaments. Although the conclusions are not trivial, the main result is confirmed.

  3. Particles trajectories in magnetic filaments

    International Nuclear Information System (INIS)

    Bret, A.

    2015-01-01

    The motion of a particle in a spatially harmonic magnetic field is a basic problem involved, for example, in the mechanism of formation of a collisionless shock. In such settings, it is generally reasoned that particles entering a Weibel generated turbulence are trapped inside it, provided their Larmor radius in the peak field is smaller than the field coherence length. The goal of this work is to put this heuristic conclusion on firm ground by studying, both analytically and numerically, such motion. A toy model is analyzed, consisting of a relativistic particle entering a region of space occupied by a spatially harmonic field. The particle penetrates the magnetic structure in a direction aligned with the magnetic filaments. Although the conclusions are not trivial, the main result is confirmed

  4. Particles trajectories in magnetic filaments

    Science.gov (United States)

    Bret, A.

    2015-07-01

    The motion of a particle in a spatially harmonic magnetic field is a basic problem involved, for example, in the mechanism of formation of a collisionless shock. In such settings, it is generally reasoned that particles entering a Weibel generated turbulence are trapped inside it, provided their Larmor radius in the peak field is smaller than the field coherence length. The goal of this work is to put this heuristic conclusion on firm ground by studying, both analytically and numerically, such motion. A toy model is analyzed, consisting of a relativistic particle entering a region of space occupied by a spatially harmonic field. The particle penetrates the magnetic structure in a direction aligned with the magnetic filaments. Although the conclusions are not trivial, the main result is confirmed.

  5. Wireless Magnetic-Based Closed-Loop Control of Self-Propelled Microjets

    Science.gov (United States)

    Khalil, Islam S. M.; Magdanz, Veronika; Sanchez, Samuel; Schmidt, Oliver G.; Misra, Sarthak

    2014-01-01

    In this study, we demonstrate closed-loop motion control of self-propelled microjets under the influence of external magnetic fields. We control the orientation of the microjets using external magnetic torque, whereas the linear motion towards a reference position is accomplished by the thrust and pulling magnetic forces generated by the ejecting oxygen bubbles and field gradients, respectively. The magnetic dipole moment of the microjets is characterized using the U-turn technique, and its average is calculated to be 1.310−10 A.m2 at magnetic field and linear velocity of 2 mT and 100 µm/s, respectively. The characterized magnetic dipole moment is used in the realization of the magnetic force-current map of the microjets. This map in turn is used for the design of a closed-loop control system that does not depend on the exact dynamical model of the microjets and the accurate knowledge of the parameters of the magnetic system. The motion control characteristics in the transient- and steady-states depend on the concentration of the surrounding fluid (hydrogen peroxide solution) and the strength of the applied magnetic field. Our control system allows us to position microjets at an average velocity of 115 m/s, and within an average region-of-convergence of 365 m. PMID:24505244

  6. Triode for magnetic flux quanta.

    Science.gov (United States)

    Vlasko-Vlasov, Vitalii; Colauto, Fabiano; Benseman, Timothy; Rosenmann, Daniel; Kwok, Wai-Kwong

    We designed a magnetic vortex triode using an array of closely spaced soft magnetic Py strips on top of a Nb superconducting film. The strips act similar to the grid electrode in an electronic triode, where the electron flow is regulated by the grid potential. In our case, we tune the vortex motion by the magnetic charge potential of the strip edges, using a small magnetic field rotating in the film plane. The magnetic charges emerging at the stripe edges and proportional to the magnetization component perpendicular to the edge direction, form linear potential barriers or valleys for vortex motion in the superconducting layer. We directly imaged the normal flux penetration into the Py/Nb films and observed retarded or accelerated entry of the normal vortices depending on the in-plane magnetization direction in the stripes. The observed flux behavior is explained by interactions between magnetically charged lines and magnetic monopoles of vortices similar to those between electrically charged strings and point charges. We discuss the possibility of using our design for manipulation of individual vortices in high-speed, low-power superconducting electronic circuits. This work was supported by the U.S. DOE, Office of Science, Materials Sciences and Engineering Division, and Office of BES (contract DE-AC02-06CH11357). F. Colauto thanks the Sao Paulo Research Foundation FAPESP (Grant No. 2015/06.085-3).

  7. CHAOTIC MOTION OF CHARGED PARTICLES IN AN ELECTROMAGNETIC FIELD SURROUNDING A ROTATING BLACK HOLE

    International Nuclear Information System (INIS)

    Takahashi, Masaaki; Koyama, Hiroko

    2009-01-01

    The observational data from some black hole candidates suggest the importance of electromagnetic fields in the vicinity of a black hole. Highly magnetized disk accretion may play an importance rule, and large-scale magnetic field may be formed above the disk surface. Then, we expect that the nature of the black hole spacetime would be revealed by magnetic phenomena near the black hole. We will start investigating the motion of a charged test particle which depends on the initial parameter setting in the black hole dipole magnetic field, which is a test field on the Kerr spacetime. Particularly, we study the spin effects of a rotating black hole on the motion of the charged test particle trapped in magnetic field lines. We make detailed analysis for the particle's trajectories by using the Poincare map method, and show the chaotic properties that depend on the black hole spin. We find that the dragging effects of the spacetime by a rotating black hole weaken the chaotic properties and generate regular trajectories for some sets of initial parameters, while the chaotic properties dominate on the trajectories for slowly rotating black hole cases. The dragging effects can generate the fourth adiabatic invariant on the particle motion approximately.

  8. A One-Axis-Controlled Magnetic Bearing and Its Performance

    Science.gov (United States)

    Li, Lichuan; Shinshi, Tadahiko; Kuroki, Jiro; Shimokohbe, Akira

    Magnetic bearings (MBs) are complex machines in which sensors and controllers must be used to stabilize the rotor. A standard MB requires active control of five motion axes, imposing significant complexity and high cost. In this paper we report a very simple MB and its experimental testing. In this MB, the rotor is stabilized by active control of only one motion axis. The other four motion axes are passively stabilized by permanent magnets and appropriate magnetic circuit design. In rotor radial translational motion, which is passively stabilized, a resonant frequency of 205Hz is achieved for a rotor mass of 11.5×10-3kg. This MB features virtually zero control current and zero rotor iron loss (hysteresis and eddy current losses). Although the rotational speed and accuracy are limited by the resonance of passively stabilized axes, the MB is still suitable for applications where cost is critical but performance is not, such as cooling fans and auxiliary support for aerodynamic bearings.

  9. The development of equipment for the technical assessment of respiratory motion induced artefacts in MRI

    International Nuclear Information System (INIS)

    Jackson, P.C.; Davies, S.C.; Zananiri, F.V.; Follett, D.H.; Halliwell, M.; Wells, P.N.T.; Bean, J.P.

    1993-01-01

    A device and technique to study the effects of respiratory motion on the quality of magnetic resonance images is proposed. The construction of the device enables a variety of test objects to be mounted and used in the evaluation of imaging parameters that may be affected by motion. The equipment is constructed of cast acrylic and the movement is actuated and controlled pneumatically thus ensuring that there are no interactions with the magnetic field and radiofrequency detection system to cause further image artefacts. Separate studies have been performed, using ultrasound, to assess the degree and rate of movement of organs owing to respiration in order to derive the motion parameters for the apparatus. Preliminary results indicate that the technique produces motion induced artefacts simulating those which are the result of the effects of respiration. (author)

  10. Linear magnetic motor/generator. [to generate electric energy using magnetic flux for spacecraft power supply

    Science.gov (United States)

    Studer, P. A. (Inventor)

    1982-01-01

    A linear magnetic motor/generator is disclosed which uses magnetic flux to provide mechanical motion or electrical energy. The linear magnetic motor/generator includes an axially movable actuator mechanism. A permament magnet mechanism defines a first magnetic flux path which passes through a first end portion of the actuator mechanism. Another permament magnet mechanism defines a second magnetic flux path which passes through a second end portion of the actuator mechanism. A drive coil defines a third magnetic flux path passing through a third central portion of the actuator mechanism. A drive coil selectively adds magnetic flux to and subtracts magnetic flux from magnetic flux flowing in the first and second magnetic flux path.

  11. Microscopic theory of dynamical subspace for large amplitude collective motion

    International Nuclear Information System (INIS)

    Sakata, Fumihiko; Marumori, Toshio; Ogura, Masanori.

    1986-01-01

    A full quantum theory appropriate for describing large amplitude collective motion is proposed by exploiting the basic idea of the semi-classical theory so far developed within the time-depedent Hartree-Fock theory. A central problem of the quantum theory is how to determine an optimal representation called a dynamical representation specific for the collective subspace where the large amplitude collective motion is replicated as precisely as possible. As an extension of the semi-classical theory where the concept of an approximate integral surface played an important role, the collective subspace is properly characterized by introducing a concept of an approximate invariant subspace of the Hamiltonian. (author)

  12. Magnetic propulsion of microspheres at liquid-glass interfaces

    Science.gov (United States)

    Helgesen, Geir

    2018-02-01

    Bio-coated, magnetic microspheres have many applications in biotechnology and medical technology as a tool to separate and extract cells or molecules in a water solution by applying external strong magnetic field gradients. However, magnetic microspheres with or without attached cargo can also be separated in the liquid solution if they are exposed to alternating or rotating, relatively weak magnetic fields. Microspheres that have a higher density than the liquid will approach the bottom surface of the sample cell, and then a combination of viscous and surface frictional forces can propel the magnetic microspheres along the surface in a direction perpendicular to the axis of field rotation. Experiments demonstrating this type of magnetic propulsion are shown, and the forces active in the process are discussed. The motion of particles inside sample cells that were tilted relative to the horizontal direction was studied, and the variation of propulsion velocity as a function of tilt angle was used to find the values of different viscous and mechanical parameters of motion. Propulsion speeds of up to 5 μm/s were observed and were found to be caused by a partly rolling and partly slipping motion of rotating microspheres with a slipping coefficient near 0.6.

  13. Control over Janus micromotors by the strength of a magnetic field

    Science.gov (United States)

    Baraban, Larysa; Makarov, Denys; Schmidt, Oliver G.; Cuniberti, Gianaurelio; Leiderer, Paul; Erbe, Artur

    2013-01-01

    For transportation of molecules or biological cells using artificial motors, the control over their motion, i.e. direction and speed of transfer, is important. Here, we demonstrate that modification of the velocity and orientation of a magnetic Janus particle can be efficiently controlled by tuning the strength of an applied homogeneous magnetic field. Interestingly, by keeping the same orientation of the magnetic field but changing its magnitude not only the velocity of capped particles can be altered but even their direction of motion can be reversed. We put forth a simple qualitative model, which allows us to explain this intriguing observation.For transportation of molecules or biological cells using artificial motors, the control over their motion, i.e. direction and speed of transfer, is important. Here, we demonstrate that modification of the velocity and orientation of a magnetic Janus particle can be efficiently controlled by tuning the strength of an applied homogeneous magnetic field. Interestingly, by keeping the same orientation of the magnetic field but changing its magnitude not only the velocity of capped particles can be altered but even their direction of motion can be reversed. We put forth a simple qualitative model, which allows us to explain this intriguing observation. Electronic supplementary information (ESI) available: Videos (1-3) describe the behavior of the magnetic Janus micromotors at different magnetic fields applied. The magnetic field is always applied along the positive direction of the y-axis. All the movies are recorded at the same frame rate of 21 images per second. Experiments were performed at 30 wt% of hydrogen peroxide in aqueous solution. Video 1 shows the motion of the Janus micromotors when a small magnetic field is applied (B = 0.2 mT). The particle is propelled in the direction ``opposite to the cap'' with a velocity of about 6 μm s-1. Video 2 displays the motion of the same Janus bead when an intermediately strong

  14. Moving object detection using dynamic motion modelling from UAV aerial images.

    Science.gov (United States)

    Saif, A F M Saifuddin; Prabuwono, Anton Satria; Mahayuddin, Zainal Rasyid

    2014-01-01

    Motion analysis based moving object detection from UAV aerial image is still an unsolved issue due to inconsideration of proper motion estimation. Existing moving object detection approaches from UAV aerial images did not deal with motion based pixel intensity measurement to detect moving object robustly. Besides current research on moving object detection from UAV aerial images mostly depends on either frame difference or segmentation approach separately. There are two main purposes for this research: firstly to develop a new motion model called DMM (dynamic motion model) and secondly to apply the proposed segmentation approach SUED (segmentation using edge based dilation) using frame difference embedded together with DMM model. The proposed DMM model provides effective search windows based on the highest pixel intensity to segment only specific area for moving object rather than searching the whole area of the frame using SUED. At each stage of the proposed scheme, experimental fusion of the DMM and SUED produces extracted moving objects faithfully. Experimental result reveals that the proposed DMM and SUED have successfully demonstrated the validity of the proposed methodology.

  15. On the Motion of the Field of a Permanent Magnet

    Science.gov (United States)

    Leus, Vladimir; Taylor, Stephen

    2011-01-01

    A description is given of a series of recent experiments using a rotating magnetic circuit comprising a permanent magnet ring and yoke, and a stationary conductor in the air gap between the ring and yoke. The EMF induced in this case cannot be described by a simple application of Faraday's flux law. This is because the magnetic flux in the air gap…

  16. SU-F-J-151: Evaluation of a Magnetic Resonance Image Gated Radiotherapy System Using a Motion Phantom and Radiochromic Film

    Energy Technology Data Exchange (ETDEWEB)

    Lamb, J; Ginn, J; O’Connell, D; Thomas, D; Agazaryan, N; Cao, M; Yang, Y; Low, D [UCLA, Los Angeles, CA (United States)

    2016-06-15

    Purpose: Magnetic resonance image (MRI) guided radiotherapy enables gating directly on target position for soft-tissue targets in the lung and abdomen. We present a dosimetric evaluation of a commercially-available FDA-approved MRI-guided radiotherapy system’s gating performance using a MRI-compatible respiratory motion phantom and radiochromic film. Methods: The MRI-compatible phantom was capable of one-dimensional motion. The phantom consisted of a target rod containing high-contrast target inserts which moved inside a body structure containing background contrast material. The target rod was equipped with a radiochromic film insert. Treatment plans were generated for a 3 cm diameter spherical target, and delivered to the phantom at rest and in motion with and without gating. Both sinusoidal and actual tumor trajectories (two free-breathing trajectories and one repeated-breath hold) were used. Gamma comparison at 5%/3mm was used to measure fidelity to the static target dose distribution. Results: Without gating, gamma pass rates were 24–47% depending on motion trajectory. Using our clinical standard of repeated breath holds and a gating window of 3 mm with 10% of the target allowed outside the gating boundary, the gamma pass rate was 99.6%. Relaxing the gating window to 5 mm resulted in gamma pass rate of 98.6% with repeated breath holds. For all motion trajectories gated with 3 mm margin and 10% allowed out, gamma pass rates were between 64–100% (mean:87.5%). For a 5 mm margin and 10% allowed out, gamma pass rates were between 57–98% (mean: 82.49%), significantly lower than for 3 mm by paired t-test (p=0.01). Conclusion: We validated the performance of respiratory gating based on real-time cine MRI images with the only FDA-approved MRI-guided radiotherapy system. Our results suggest that repeated breath hold gating should be used when possible for best accuracy. A 3 mm gating margin is statistically significantly more accurate than a 5 mm gating margin.

  17. Holding or Breaking with Ptolemy's Generalization: Considerations about the Motion of the Planetary Apsidal Lines in Medieval Islamic Astronomy.

    Science.gov (United States)

    Mozaffari, S Mohammad

    2017-03-01

    Argument In the Almagest, Ptolemy finds that the apogee of Mercury moves progressively at a speed equal to his value for the rate of precession, namely one degree per century, in the tropical reference system of the ecliptic coordinates. He generalizes this to the other planets, so that the motions of the apogees of all five planets are assumed to be equal, while the solar apsidal line is taken to be fixed. In medieval Islamic astronomy, one change in this general proposition took place because of the discovery of the motion of the solar apogee in the ninth century, which gave rise to lengthy discussions on the speed of its motion. Initially Bīrūnī and later Ibn al-Zarqālluh assigned a proper motion to it, although at different rates. Nevertheless, appealing to the Ptolemaic generalization and interpreting it as a methodological axiom, the dominant idea became to extend it in order to include the motion of the solar apogee as well. Another change occurred after correctly making a distinction between the motion of the apogees and the rate of precession. Some Western Islamic astronomers generalized Ibn al-Zarqālluh's proper motion of the solar apogee to the apogees of the planets. Analogously, Ibn al-Shāṭir maintained that the motion of the apogees is faster than precession. Nevertheless, the Ptolemaic generalization in the case of the equality of the motions of the apogees remained untouchable, despite the notable development of planetary astronomy, in both theoretical and observational aspects, in the late Islamic period.

  18. Experimental Study on Position Control System Using Encoderless Magnetic Motion

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong Youn; Heo, Hoon [Korea Univ., Seoul (Korea, Republic of); Yun, Young Min; Shim, Ho Keun; Kwon, Young Mok [TPC Mechatronics, Daejeon (Korea, Republic of)

    2016-01-15

    A position control system composed of the PMLSM(Permanent Magnet Linear Synchronous Motor), unlike conventional linear permanent magnet synchronous motor is fixed to the permanent magnet moving coil rails (permanent magnet = stator, coil = mover), the coil is fixed, moving the permanent magnet, we propose a position control system (permanent magnet = mover, coil = stator) structure. Position is measured not using conventional encoder or resolver but by adopting vector control method using 2 hall sensors generating rectangular signal. This method estimate the velocity and position of mover by using the quadruple of two hall sensor signal instead of encoder signal. Vector control of PMLSM using 2 hall sensor generating rectangular wave is proved to control the system stable and efficiently through simulation. Also hardware experiment reveals that the position control performance is measured within the range of 30-50μ in the accuracy of 10-20μ, which is improved twice to the conventional method. The proposed method exhibits its economical efficiency and practical usefulness. The vector control technique using two hall sensors can be installed in narrow place, accordingly it can be implemented on the system where the conventional encoder or resolver cannot operate.

  19. A quasi-relativistic treatment of nuclear motion in atoms and molecules

    International Nuclear Information System (INIS)

    Chen, W.Q.; Cook, A.H.

    1987-01-01

    A quasi-relativistic Hamiltonian for an atom and a molecule is constructed. The Foldy-Wouthuysen transformation is applied to the Hamiltonian. Consequently, extra terms from interactions between the electronic motion and the nuclear magnetic field contributing to the Darwin term and the spin-orbit coupling are derived explicitly. Moreover, the coupling between nuclear motion and the spin of the electron is obtained. (author)

  20. Counter-current motion in counter-current chromatography.

    Science.gov (United States)

    Ito, Yoichiro

    2014-12-12

    After the CCC2012 meeting, I have received an e-mail regarding the terminology of "Countercurrent Chromatography". It stated that the term "Countercurrent" is a misnomer, because its stationary phase is motionless in the column and that the method should be renamed as liquid-liquid separations or centrifugal separations. However, it was found that these names are already used for various other techniques as found via Google search. The term "Countercurrent Chromatography" was originally made after two preparative methods of Countercurrent distribution and liquid Chromatography, both having no countercurrent motion in the column. However, it is surprising to find that this F1 hybrid method "Countercurrent Chromatography" can clearly exhibit countercurrent motion within the separation column in both hydrodynamic and hydrostatic equilibrium systems. This justifies that "Countercurrent Chromatography" is a proper term for this chromatographic method. Published by Elsevier B.V.

  1. THE ALLWISE MOTION SURVEY, PART 2

    Energy Technology Data Exchange (ETDEWEB)

    Kirkpatrick, J. Davy; Kellogg, Kendra; Fajardo-Acosta, Sergio; Gelino, Christopher R.; Schurr, Steven D.; Cutri, Roc M.; Conrow, Tim [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Schneider, Adam C.; Cushing, Michael C.; Greco, Jennifer [Department of Physics and Astronomy, MS 111, University of Toledo, 2801 W. Bancroft Street, Toledo, OH 43606-3328 (United States); Mace, Gregory N. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Wright, Edward L.; Logsdon, Sarah E.; Martin, Emily C.; McLean, Ian S. [Department of Physics and Astronomy, UCLA, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547 (United States); Eisenhardt, Peter R. M.; Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Faherty, Jacqueline K.; Sheppard, Scott S. [Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015 (United States); Lansbury, George B., E-mail: davy@ipac.caltech.edu [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)

    2016-06-01

    We use the AllWISE Data Release to continue our search for Wide-field Infrared Survey Explorer ( WISE )-detected motions. In this paper, we publish another 27,846 motion objects, bringing the total number to 48,000 when objects found during our original AllWISE motion survey are included. We use this list, along with the lists of confirmed WISE -based motion objects from the recent papers by Luhman and by Schneider et al., and candidate motion objects from the recent paper by Gagné et al., to search for widely separated, common-proper-motion systems. We identify 1039 such candidate systems. All 48,000 objects are further analyzed using color–color and color–mag plots to provide possible characterizations prior to spectroscopic follow-up. We present spectra of 172 of these, supplemented with new spectra of 23 comparison objects from the literature, and provide classifications and physical interpretations of interesting sources. Highlights include: (1) the identification of three G/K dwarfs that can be used as standard candles to study clumpiness and grain size in nearby molecular clouds because these objects are currently moving behind the clouds, (2) the confirmation/discovery of several M, L, and T dwarfs and one white dwarf whose spectrophotometric distance estimates place them 5–20 pc from the Sun, (3) the suggestion that the Na i “D” line be used as a diagnostic tool for interpreting and classifying metal-poor late-M and L dwarfs, (4) the recognition of a triple system including a carbon dwarf and late-M subdwarf, for which model fits of the late-M subdwarf (giving [Fe/H] ≈ −1.0) provide a measured metallicity for the carbon star, and (5) a possible 24 pc distant K5 dwarf + peculiar red L5 system with an apparent physical separation of 0.1 pc.

  2. THE ALLWISE MOTION SURVEY, PART 2

    International Nuclear Information System (INIS)

    Kirkpatrick, J. Davy; Kellogg, Kendra; Fajardo-Acosta, Sergio; Gelino, Christopher R.; Schurr, Steven D.; Cutri, Roc M.; Conrow, Tim; Schneider, Adam C.; Cushing, Michael C.; Greco, Jennifer; Mace, Gregory N.; Wright, Edward L.; Logsdon, Sarah E.; Martin, Emily C.; McLean, Ian S.; Eisenhardt, Peter R. M.; Stern, Daniel; Faherty, Jacqueline K.; Sheppard, Scott S.; Lansbury, George B.

    2016-01-01

    We use the AllWISE Data Release to continue our search for Wide-field Infrared Survey Explorer ( WISE )-detected motions. In this paper, we publish another 27,846 motion objects, bringing the total number to 48,000 when objects found during our original AllWISE motion survey are included. We use this list, along with the lists of confirmed WISE -based motion objects from the recent papers by Luhman and by Schneider et al., and candidate motion objects from the recent paper by Gagné et al., to search for widely separated, common-proper-motion systems. We identify 1039 such candidate systems. All 48,000 objects are further analyzed using color–color and color–mag plots to provide possible characterizations prior to spectroscopic follow-up. We present spectra of 172 of these, supplemented with new spectra of 23 comparison objects from the literature, and provide classifications and physical interpretations of interesting sources. Highlights include: (1) the identification of three G/K dwarfs that can be used as standard candles to study clumpiness and grain size in nearby molecular clouds because these objects are currently moving behind the clouds, (2) the confirmation/discovery of several M, L, and T dwarfs and one white dwarf whose spectrophotometric distance estimates place them 5–20 pc from the Sun, (3) the suggestion that the Na i “D” line be used as a diagnostic tool for interpreting and classifying metal-poor late-M and L dwarfs, (4) the recognition of a triple system including a carbon dwarf and late-M subdwarf, for which model fits of the late-M subdwarf (giving [Fe/H] ≈ −1.0) provide a measured metallicity for the carbon star, and (5) a possible 24 pc distant K5 dwarf + peculiar red L5 system with an apparent physical separation of 0.1 pc.

  3. The Flares Associated with the Dynamics of the Sunspots K. M. ...

    Indian Academy of Sciences (India)

    tional theory of magnetic reconnection is briefly discussed. ... between changes in the sunspots' dynamics, emerging flux region, twisting of the field ... the eventual triggering of the flares is due to proper motion of the sunspots. Using .... rotation rates obtained from the daily motion of sunspot groups with respect to their life.

  4. The motion of trapped secondary particles in a storage ring

    International Nuclear Information System (INIS)

    Shamovskij, V.G.

    1994-01-01

    The longitudinal motion of secondary electrons and ions trapped by an electron circulating beam field in nonuniform magnetic field of the storage ring is studied analytically. The conditions for their reflection in the fringe field of the storage ring magnet and in the sing-alternating field of the undulator are found. The calculations are made for the probability of this reflection in the case of ion generated in a straight section, in the region of a zero magnetic field. 12 refs.; 4 figs

  5. Towards proper name generation : A corpus analysis

    NARCIS (Netherlands)

    Castro Ferreira, Thiago; Wubben, Sander; Krahmer, Emiel

    We introduce a corpus for the study of proper name generation. The corpus consists of proper name references to people in webpages, extracted from the Wikilinks corpus. In our analyses, we aim to identify the different ways, in terms of length and form, in which a proper names are produced

  6. Electric field control of magnon-induced magnetization dynamics in multiferroics.

    Science.gov (United States)

    Risinggård, Vetle; Kulagina, Iryna; Linder, Jacob

    2016-08-24

    We consider theoretically the effect of an inhomogeneous magnetoelectric coupling on the magnon-induced dynamics of a ferromagnet. The magnon-mediated magnetoelectric torque affects both the homogeneous magnetization and magnon-driven domain wall motion. In the domains, we predict a reorientation of the magnetization, controllable by the applied electric field, which is almost an order of magnitude larger than that observed in other physical systems via the same mechanism. The applied electric field can also be used to tune the domain wall speed and direction of motion in a linear fashion, producing domain wall velocities several times the zero field velocity. These results show that multiferroic systems offer a promising arena to achieve low-dissipation magnetization rotation and domain wall motion by exciting spin-waves.

  7. Epoxy Adhesives for Stator Magnet Assembly in Stirling Radioisotope Generators (SRG)

    Science.gov (United States)

    Cater, George M.

    2004-01-01

    As NASA seeks to fulfill its goals of exploration and understanding through missions planned to visit the moons of Saturn and beyond, a number of challenges arise from the idea of deep space flight. One of the first problems associated with deep space travel is electrical power production for systems on the spacecraft. Conventional methods such as solar power are not practical because efficiency decreases substantially as the craft moves away from the Sun. The criterion for power generation during deep space missions are very specific, the main points requiring high reliability, low mass, minimal vibration and a long lifespan. A Stirling generator, although fairly old in concept, is considered to be a potential solution for electrical power generation for deep space flight. A Stirling generator works on the same electromagnetic principles of a standard generator, using the linear motion of the alternator through the stationary stator which produces electric induction. The motion of the alternator, however, is produced by the heating and cooling dynamics of pressurized gases. Essentially heating one end and cooling another of a contained gas will cause a periodic expansion and compression of the gas from one side to the other, which a displacer translates into linear mechanical motion. NASA needs to confirm that the materials used in the generator will be able to withstand the rigors of space and the life expectancy of the mission. I am working on the verification of the epoxy adhesives used to bond magnets to the steel lamination stack to complete the stator; in terms of in-service performance and durability under various space environments. Understanding the proper curing conditions, high temperature properties, and degassing problems as well as production difficulties are crucial to the long term success of the generator. system and steel substrate used in the stator. To optimize the curing conditions of the epoxies, modulated differential scanning calorimetry

  8. PropeR revisited

    NARCIS (Netherlands)

    van der Linden, Helma; Talmon, Jan; Tange, Huibert; Grimson, Jane; Hasman, Arie

    2005-01-01

    INTRODUCTION: The PropeR EHR system (PropeRWeb) is a multidisciplinary electronic health record (EHR) system for multidisciplinary use in extramural patient care for stroke patients. DESIGN: The system is built using existing open source components and is based on open standards. It is implemented

  9. Magnetic Field

    DEFF Research Database (Denmark)

    Olsen, Nils

    2015-01-01

    he Earth has a large and complicated magnetic field, the major part of which is produced by a self-sustaining dynamo operating in the fluid outer core. Magnetic field observations provide one of the few tools for remote sensing the Earth’s deep interior, especially regarding the dynamics...... of the fluid flow at the top of the core. However, what is measured at or near the surface of the Earth is the superposition of the core field and fields caused by magnetized rocks in the Earth’s crust, by electric currents flowing in the ionosphere, magnetosphere, and oceans, and by currents induced...... in the Earth by time-varying external fields. These sources have their specific characteristics in terms of spatial and temporal variations, and their proper separation, based on magnetic measurements, is a major challenge. Such a separation is a prerequisite for remote sensing by means of magnetic field...

  10. MSPT: Motion Simulator for Proton Therapy

    International Nuclear Information System (INIS)

    Morel, Paul

    2014-01-01

    In proton therapy, the delivery method named spot scanning, can provide a particularly efficient treatment in terms of tumor coverage and healthy tissues protection. The dosimetric benefits of proton therapy may be greatly degraded due to intra-fraction motions. Hence, the study of mitigation or adaptive methods is necessary. For this purpose, we developed an open-source 4D dose computation and evaluation software, MSPT (Motion Simulator for Proton Therapy), for the spot-scanning delivery technique. It aims at highlighting the impact of intra-fraction motions during a treatment delivery by computing the dose distribution in the mo